Urea exchange across the human erythrocyte membrane measured using 13C NMR lineshape analysis.

The 13C NMR spectrum of 13C-urea in a suspension of human red cells of reduced mean cell volume was observed to contain partially resolved resonances arising from the intra- and extracellular populations of the compound. It was shown that at 25 degrees C and a magnetic field strength of 9.4 T, the rate of exchange of urea between the intra- and extracellular populations was such that the NMR lineshape was sensitive to a change in the rate of 13C-urea exchange, induced either by the addition of the urea transport inhibitor phloretin, or by the addition of 12C-urea. Total lineshape analysis of 13C NMR spectra of 13C-urea in red cell suspensions containing different concentrations of 12C-urea resulted in a weighted mean estimate for the Km and Vmax for urea equilibrium exchange from three experiments of 44 +/- 18 mM and 3.1 +/- 0.6 x 10(-8) mol cm-2 s-1, respectively (the errors denote the weighted mean standard deviations). These estimates of Km and Vmax were significantly lower than previous values reported in the literature and determined using other techniques.


MNDO study of the mechanism of the inhibition of cysteine proteinases by diazomethyl ketones.

Diazomethyl ketones are one of the most effective irreversible inhibitors of cysteine proteinases and are therefore very important in drug design. In the present study a mechanism of inactivation is proposed based on the results of model MNDO calculations of the possible pathways. It was found that the mercaptide nucleophile, on approaching the carbonyl carbon as in the catalytic reaction path, binds to the inner diazo nitrogen. The intermediate thus formed can rearrange giving a stable product, beta-thioketone, and molecular nitrogen, with a considerable energy gain. The energy barrier to this process is equal to 36.9 kcal/mol, and corresponds to a pyramidal transition state with the vertex at the methylene carbon and the base formed by the carbonyl, thiol, and diazo groups. The energy barrier can be lowered on deprotonation of the intermediate. Based on the results obtained it was concluded that good irreversible inhibitors of cysteine proteases must fulfil two structural requirements: i) the dimensions and charge distribution must be similar to those of the peptide bond and ii) a second electrophilic center must be present in the neighbourhood of the carbonyl carbon. These are requirements which are satisfied by other strong cysteine proteinase inhibitors: beta-chloroketones and beta-ketooxiranes.


The elastic deformability of closed multilayered membranes is the same as that of a bilayer membrane.

The elastic behavior of closed multilayered membranes is analyzed with the assumption that the constituent layers are in close contact but are unconnected in the sense that they are free to slide by one another. The system exhibits three independent elastic deformation modes for any number of the constituent layers equal to or larger than two. These are the area expansivity of the membrane neutral surface, and the local and non-local membrane bending. The corresponding elastic moduli are expressed in terms of the elastic moduli of the constituent layers, their areas, and distances between their neutral surfaces. Closed multilayered membranes only differ from a closed bilayer membrane in that for any of their shapes some of the constituent layers are expanded and some compressed.


Direct spectroscopic determination of functional sulphydryl groups on intact cell surfaces by surface-enhanced resonance Raman scattering.

Semi-quantitative and direct determination of labelled sulphydryl groups on the surface of intact erythrocytes has been accomplished for the first time with surface-enhanced resonance Raman scattering (SERRS). The method, which involves the use of citrate-reduced silver colloids, is sensitive and selective. A 10(-8) M effective concentration of picomole quantities of sulphydryl groups was determined in the presence of the normally overwhelming signal from haemoglobin. This seminal study suggests that SERRS may be applied to other in situ, site-directed labelling experiments.


Investigation of the inhibition pathway of glucosamine synthase by N3-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid by semiempirical quantum mechanical and molecular mechanics methods.

Glucosamine synthase (E.C. 2.6.1.16) is a promising target in antifungal drug design. It has been reported that its potent inhibitor, N3-(4-methoxyfumaroyl)-L-2,3-diaminopropanoic acid (FMDP), inactivates the enzyme by the Michael addition of the S-H group to the FMDP molecule followed by cyclisation reactions. In this study we have investigated, by means of semiempirical MNDO, PM3 and molecular mechanics methods, the energetics and kinetic possibility of the formation of various stereoisomers of the products of cyclisation of the Michael addition products detected experimentally. It was found that the substituted 1,4-thiazin-3-one can be formed in one step under alkaline conditions; the stereoisomers of this compound predicted to be the most stable on the basis of theoretical calculations are also the dominant ones in reality.


Differential sensitivity of cardiac K+(ATP) channels to guanine nucleotides--evidence for a heterogeneous channel population.

In cell-free patches from cultured neonatal rat cardiocytes, the cytosolic presence of GTP-gamma-S (100 mumol/l) or GDP-beta-S (100 mumol/l) activated K+(ATP) channels. GTP-gamma-S required cytosolic Mg++, suggesting that an activated G-protein causes the increase in open probability. The great variations of the channel response to GTP-gamma-S and GDP-beta-S indicates that cardiac K+(ATP) channels represent a heterogeneous family.


Intracellular signaling in the gonads.

The regulation of steroidogenesis in both the ovary and testis involves a complex interaction of a diversity of hormones and intracellular signaling pathways. The recent cloning of LH and FSH receptors has paved the way for an increased understanding of the mechanisms of receptor conformation, ligand-receptor interaction, and facilitation of post-receptor activity. The dominant role played by LH in the regulation of steroid production appears to be mediated by more than one intracellular signaling pathway. In addition to the stimulation of the adenylate cyclase-cAMP pathway, also known to be stimulated by FSH, the actions of LH may be additionally mediated by other intracellular messengers, such as those derived from the PLC pathway. Steroidogenesis in the gonads appears to be modulated by a variety of factors in addition to the gonadotropins. In this review, those factors of intracellular signaling mechanisms of which we have some understanding have been discussed. These include GnRH, PGF2 alpha, Ang II, VIP, GHRH, TNF alpha, CRF, EGF, and TGF alpha. Many of these factors have been shown to be locally synthesized, and specific receptors have been identified in the gonads. Many gonadal factors have the capacity to exert effects on steroidogenesis independent of the gonadotropins. Alternately, they have been demonstrated to alter the gonadal response to the gonadotropins via autocrine, paracrine, and intracrine mechanisms. As yet, our understanding of the intracellular signaling mechanisms used by novel gonadal regulators is limited. The involvement of the PLC, PLA2, and PLD pathways in this regard has been reviewed. It is becoming apparent that multiple signaling pathways may be stimulated by a single hormone, as in the case of GnRH, PGF2 alpha, and LH. The complexity of intracellular signal transduction in the gonads is enhanced by the potential cross-talk at numerous steps in the signaling cascades.


Secretion of peptides and proteins lacking hydrophobic signal sequences: the role of adenosine triphosphate-driven membrane translocators.

In this review, we will emphasize the role of ATP-dependent membrane transporters in protein export and intracellular protein trafficking in prokaryotic and eukaryotic cells. ATP-binding-cassette (ABC)-transport proteins, also termed "traffic ATPases," belong to a superfamily of ubiquitous ATP-driven membrane transporters that share extensive sequence similarity and highly conserved domain organization. They are implicated in a remarkable variety of transmembrane transport processes, including the transport of ions, heavy metals, sugars, anticancer drugs, amino acids, oligopeptides, and proteins. Bacterial ABC-proteins include the well-characterized periplasmic permeases involved in nutrient uptake, but also include protein secretion systems, such as the exporter for the Escherichia coli enterotoxin hemolysin A. Prominent eukaryotic members of this superfamily include the human P-glycoprotein (which is associated with the phenomenon of multiple drug resistance in tumor cells), the product of the cystic fibrosis gene (CFTR), the gene (pfmdr) implicated in chloroquine resistance of the malarial parasite, putative peptide transporters encoded at the locus for the class II major histocompatibility complex (MHC), and the yeast Ste6 transporter which mediates export of a peptide hormone that lacks a classical hydrophobic signal peptide. The well-established function of prokaryotic ABC-transporters in the secretion of proteins without typical signal sequences, and the example set by the Ste6 transporter, have led to the reasonable hypothesis that certain ABC-proteins in animal cells may be operating by a similar mechanism to mediate the export of a new class of secretory proteins, those lacking a classical hydrophobic signal peptide.


Interleukin-1 and beta-cell function: more than one second messenger?

Cytokines, in particular IL-1, released mainly by infiltrating macrophages, can be one of the key mediators of immune-induced beta-cell destruction in IDDM. IL-1 is able to induce suppression of insulin release and biosynthesis in cultured rat pancreatic islets. In addition, the cytokine shows clear cytotoxic effects leading to beta-cell death. The proposed mechanisms of action of IL-1 after binding to the beta-cell receptors are varied. Concerning the cytotoxic effects of the cytokine, the role of oxygen free radicals, mainly derived from arachidonate metabolism (see Fig. 1) is clear, and possibly potentiated by a cytosolic Na(+)-mediated alkalinization of the beta-cell exposed to the cytokine. In fact, an increased influx of Na+ may explain some of the cytotoxicity since it results in concomitant water uptake leading to swelling of the endoplasmic reticulum. NO formation also seems to be related to the cytokine-induced cytotoxicity since inhibition of the NO synthase abolishes the effects of the cytokine (see Fig. 1). In relation to the inhibitory effects of the cytokine on the beta-cell, different studies point toward almost all known second messenger systems already described for several hormones, such as cAMP formation, increased phospholipase C activity, changes in cytosolic Ca++, and altered gene transcription (see Fig. 1). Of particular interest is the protease activation associated with IL-1 (a serine protease) that seems to be clearly connected with the effects of the cytokine upon the beta-cell. In conclusion, the different studies devoted to the problem of IL-1 signal transduction on the beta-cell seem to indicate that the action of the cytokine on the pancreatic insulin-secreting cells is not associated with an individual second messenger system but rather seems to be related to a plurifactorial transduction system.


Status epilepticus in children, adults, and the elderly.

Status epilepticus (SE) is a major neurological and medical emergency associated with a high morbidity and mortality. Retrospective and prospective studies from the Medical College of Virginia Epilepsy Research Center have been utilized to investigate several clinical and epidemiological factors associated with SE. Univariate and multivariate logistic regression analysis of predictive indicators in patients with SE indicated that seizure duration, certain specific etiologies, and age were predictors of mortality. Sex, race, and certain other etiologies were not found to be factors that significantly affect mortality. These findings demonstrate that specific indicators are important in predicting mortality in SE. Preliminary prospective epidemiological data from Richmond, Virginia suggested that more than 250,000 cases of SE may occur annually in the United States with a mortality greater than 55,000 individuals. Studies comparing community and university hospitals in Richmond indicate that the mortality and clinical variables associated with SE in these two hospital populations are essentially identical. Further investigations employing prospective population-based studies are essential in evaluating the epidemiology and mortality of SE.


Metabolism of antiepileptic medication: newborn to elderly.

Epilepsy affects individuals of all ages. Regimens of antiepileptic drugs (AEDs) and side-effect profiles differ for infants, children, adults, and the elderly. Thus, the epileptologist must be familiar with the specific changes of AED metabolism with age. In general, metabolic rates are fastest in children; therefore, AED half-lives are shortest in this group. Rates of AED elimination are slowest in neonates, infants, and children. Thus, children need larger dosages, on a mg/kg basis, than adults. The usual phenytoin (PHT) dosage in adults is 4-6 mg/kg per day, but children may need a dosage three to five times higher. On the other hand, the PHT dosages in the elderly may need to be 3-4 mg/kg per day to achieve therapeutic levels. Likewise, the half-life of carbamazepine (CBZ) is shortest in children and the elderly. Profiles of metabolites may also be age-specific, a difference of particular importance for valproate (VPA). The relative amount of VPA metabolized to 4-ene is more than twofold less in adults than in children, which may explain the different profile of hepatotoxicity seen by age. The elderly may be more vulnerable to adverse effects of AEDs. Many elderly have neurologic deficits that may render them more vulnerable to neurotoxic effects such as ataxia and cognitive disturbances. Also, low serum albumin concentrations, which result in decreased binding, may mask high serum AED concentrations. The hyponatremia associated with CBZ may be a particular concern in the elderly. Gingival hyperplasia, a concern in children, may not be a problem in the elderly.


Pregnancy and the risk of teratogenicity.

One in every 250 newborns is exposed to antiepileptic drugs (AEDs) in utero. Various studies have attributed a teratogenic effect to these AEDs, mainly consisting of major malformations, minor anomalies, intrauterine or postnatal growth failure, and psychomotor retardation. Prospective studies confirm the increased risk of major malformations. The absolute risk of 7-10% is about 3-5% higher than that in the general population. Barbiturates and phenytoin (PHT) are particularly associated with congenital heart malformations, facial clefts, and some other malformations. Valproate (VPA) and carbamazepine (CBZ) are associated predominantly with spina bifida aperta (1-2 and 0.5-1.0% risk, respectively) and hypospadias. Bilateral radial aplasia is a rare but specific effect of VPA. Several studies identified additional risk factors, i.e., high daily AED dosage, high maternal serum AED concentrations, low folate levels, or polytherapy [phenobarbital (PB) plus primidone (PRM) plus PHT or CBZ plus VPA plus PB with or without PHT]. The few prospective studies controlled for socioeconomic factors or that considered parental findings indicate that risk of specific cognitive defects rather than risk of overall mental retardation may be increased, that early growth retardation is followed by a catch-up growth to normal, and that ocular hypertelorism and nail hypoplasia are the only minor anomalies causally related to PHT exposure. However, no final conclusions can be made. Genetic predisposition to the teratogenic side effects of AEDs plays a role, codetermining the recurrence risk if the woman has previously given birth to a child with a major malformation. The molecular genetic basis of this predisposition is unclear.(ABSTRACT TRUNCATED AT 250 WORDS)


Hormones and epilepsy through the lifetime.

Hormones influence brain function from gestation throughout life and may affect the seizure threshold by altering neuronal excitability. Estrogen enhances and progesterone diminishes neuronal excitability experimentally, whereas testosterone and corticosteroids have less consistent effects. Hormonal effects in the CNS also depend on the region of brain in which the hormone acts. Sites of action for most steroid hormones include the hypothalamus and limbic cortex, providing a mechanism for modulating behavior and endocrine function. Seizure patterns may change at certain life stages, perhaps as a result of alterations in hormones. At puberty, epilepsy and benign rolandic epilepsy often remit, while juvenile myoclonic and photosensitive epilepsy may arise. Other types of epilepsy do not respond predictably to events in the reproductive life or to advancing age. In some women, fluctuations in hormones over the menstrual cycle appear to increase seizure vulnerability, probably reflecting changes in relative amounts of estrogen and progesterone. Seizure patterns can be altered, for better or worse, during pregnancy. Whether this reflects the effects of hormones or changes in levels of antiepileptic drugs is not resolved. More information is needed about changes in established epilepsy at menopause and in the elderly. Better understanding of endocrine effects on seizures over a lifetime should lead to more effective epilepsy therapies.


Seizure disorders: the changes with age.

Age has a profound influence on our approach to the convulsive disorders. Age is a variable which is an important determinant for risk factors for epilepsy. Age, as a surrogate of brain maturation, is a determinant of the specific characteristics of the seizure disorder in those with epilepsy, and age-related changes in these manifestations can be identified. Age is a determinant for the occurrence of acute symptomatic seizures in several types of metabolic or central nervous system insults. Age is a determinant for prognosis, whether one considers remission, medication withdrawal in those entering remission, relapse following prolonged remission, or mortality. Last, age per se seems to be a risk factor for epilepsy independent of other factors. This seems particularly true for partial seizures.


Effects of high-dose gamma-vinyl GABA (vigabatrin) administration on visual and somatosensory evoked potentials in dogs.

gamma-Vinyl GABA (GVG, vigabatrin) is a GABA transaminase-inhibiting antiepileptic agent. In dogs, chronic GVG administration produces reversible microvacuolation (intramyelinic edema) in discrete brain regions and slowing in central afferent transmission as measured by somatosensory evoked potentials (SEPs). Because this microvacuolation is especially prominent in the optic tract, this study tested the sensitivity of visual evoked potentials (VEPs) to GVG-induced changes in conduction. We also replicated the earlier SEP findings. Eight beagles received daily oral vigabatrin at the maximum tolerated dose (300 mg/kg/day); four were placebo controls. Cortical VEPs and SEPs were recorded using scalp needle electrodes at baseline and every 2 weeks throughout treatment. One treatment dog died at 2 weeks. The remainder showed an increase in central latencies beginning at 6 weeks, attaining significance (p < 0.05) at 8 and 10 weeks for SEPs and VEPs, respectively. No changes occurred in peripheral or spinal conduction in treated dogs, or in any measure in control dogs. Three GVG and two control dogs were followed after drug was withdrawn; both VEP and SEP measures returned to baseline values within 5 weeks. These findings support the use of VEPs and SEPs to monitor patients receiving vigabatrin therapy.


Treatment of pediatric epilepsies with gamma-vinyl GABA (vigabatrin).

Three large studies, all including more than 60 children, on the efficacy on gamma-vinyl GABA (vigabatrin, GVG) in the treatment of childhood epilepsy have been reviewed. On the basis of these and other studies, we conclude that (a) GVG is a promising drug for the treatment of childhood epilepsy, (b) GVG is effective both in partial and generalized epilepsies, (c) GVG seems to be effective in the treatment of symptomatic infantile spasms, (d) no clear dose-response relationship has been demonstrated, (e) a dose of 40-80 mg/kg/day is recommended, and (f) although tolerance is excellent, hyperactivity seems to occur more frequently in children than in adults.


Gamma-vinyl GABA (vigabatrin): clinical experience in adult and adolescent patients with intractable epilepsy.

Clinical experience with gamma-vinyl GABA (GVG, vigabatrin) has accumulated mainly in Europe, where the drug has been licensed in several countries since 1989. Short-term efficacy studies in adolescent and adult patients with intractable drug-resistant epilepsy have shown that approximately 50% exhibit a reduction in seizure frequency of one-half or more but rarely complete seizure control. The best results are in patients with partial seizures with or without secondarily generalization. GVG responders have been followed for periods of up to 5 years, and overall 10-20% may exhibit subsequent seizure breakthrough, as probably occurs with any drug in such chronic patients. The most common side effect is drowsiness. Reversible behavior disorders, psychoses, and depression rarely occur in predisposed individuals. No new long-term side effects have been reported but vigilance is necessary. Studies of GVG as a first-line drug in newly diagnosed epileptic patients are proceeding.


Hidden assumptions in environmental research.

A major challenge in both the design of epidemiologic studies of exposure to toxic agents and the interpretation of the findings is to recognize and to accommodate the complex biologic assumptions that underlie population-based research. Environmental health research is grounded on a scientific foundation that blends toxicology with epidemiology. Toxicology without human population studies often leads to findings uninterpretable for purposes of risk assessment. Epidemiologic studies are often less helpful than they could be because the variation in response is seldom addressed, the effects under study are often small in magnitude and easily confounded, and exposure estimates are crude. The net bias is to reduce the risk estimate, perhaps substantially. Biological variation has usually been treated as "noise" in the system but it is a more basic problem that lends itself to investigation and quantification. Improved modeling of the biological determinants of response is needed if results are to be generalizable and interpretable in mechanistic terms.


Environmental health in the journals.

The environmental health aspects of general medical practice have attracted the attention of many professional organizations in the past few years, including the American College of Physicians, the Institute of Medicine, and the American College of Occupational Medicine. To assess the degree of emphasis placed on environmental health issues in professional journals, a survey of representative specialty and general medical journals was conducted through a Medline literature search. Over the past 15-year period (1976-1990) specialty journals demonstrated a dramatic and consistent increase in published articles that were indexed under the headings environmental pollution, environmental pollutants, and environmental cancer. General medical journals also demonstrated continued increases in the rate of published articles addressing these environmental health topics. Within the environmental categories, air pollution, especially that due to dusts, was the most heavily indexed topic, followed by water pollution, especially that due to chemical contamination. This study supports the notion that environmental health issues are assuming more importance in general medical practice, especially within the specialty of occupational medicine.


Challenges of worker notification in neurotoxic studies of the central nervous system.

Researchers who study the central nervous system (CNS) face special challenges in notifying study participants about the research results. There are human research guidelines regarding the communication of information to subjects at the outset of a CNS research study. Yet there are few guidelines on how to communicate to the subject the research findings and the interpretation of individual results at the study's conclusion. The research subjects may desire detailed information, unequivocal conclusions, understandable interpretations, and clear suggestions about what to do next. Fulfilling these needs, however, is not a simple task for the researcher because outcomes are predicated on statistical uncertainty and the research tests may not be appropriate for individual assessment. We describe methods we have used to communicate with research subjects in two CNS neurotoxic field studies. We suggest that further research examine this important notification process.


What is a specialist? The role of board certification in occupational medicine.

A shortage of occupational medicine physicians exists for which a number of solutions have been proposed. The lack of board-certified specialists to address the increasingly complex issues encountered in this area of medicine has contributed to a credibility and identity crisis within the occupational medicine community. This article will review the significance of board certification and its importance for enhancing and preserving the specialty of occupational medicine.


Occupational and environmental hazards in art.

Artists and craftspeople, art teachers, hobbyists, and children often use art materials containing toxic chemicals without suitable precautions and often without the knowledge that their art materials are hazardous. The Center for Safety in the Arts, a national clearinghouse for research and education on hazards in the visual and performing arts, answers telephoned and written inquiries on art hazards, distributes publications, publishes a newsletter, and offers educational programs and consultative services to arts organizations.


Expiratory flows decreased in Los Angeles children from 1984 to 1987: is this evidence of effects of air pollution?

To estimate the effects of air pollution we measured expiratory flows and vital capacities in 556 Mexican-American Los Angeles children in 1984 and 251 in 1987. They included 106 who were measured in 1984 and 1987 and 145 measured only in 1987. Pulmonary function values were standardized for growth be expressing them as percentages of predicted (% pred) based on sex and height. In 1987 mean values for FEV1 and FEF25-75 were lower by 4.5% pred and 13.6% pred respectively (P < 0.001), while vital capacities were not different in 213 children tested as fifth graders in 1984 and 251 fifth grade children in 1987. For the 106 children tested at both sessions (in second grade in 1984 and in fifth grade in 1987) FVC was also not different but FEV1 was 2.0% pred lower (P < 0.06) and FEF25-75 was 7.0% pred lower (P < 0.001). For the 450 children tested only in 1984 and the 106 retested in 1987 there were no significant differences in mean values for FVC, FEV1, and FEF 25-75. Similarly there were no significant differences between the 1987 mean values for 145 children who were studied longitudinally were not different from the 1984 and 1987 cross-sectional cohorts. Across this interval FEV1 and midflows diminished but vital capacities did not. Airways obstruction worsened during children's residence in Los Angeles from 1984 to 1987 and this is probably due to air pollution.


A radiographic survey of public school building maintenance and custodial employees.

Analyses of radiographs from a cohort of 457 school maintenance and custodial workers (90 had no employment other than at a school) demonstrated an increased prevalence of abnormalities consistent with asbestos-caused disease. Pleural abnormalities predominated (24 of 29). The abnormalities could not be explained by occupational asbestos exposures which may have occurred prior to school employment. Abnormality prevalence ranged from 1.7% among those with less than 10 years to 37% among those with 30 or more years of public school employment. Laborers and skilled tradesmen with more than 20 years of school employment had a higher prevalence of abnormality (40 and 28%) than the building engineers (14%). In order to ensure that future asbestos exposure and disease risk is minimized in buildings constructed with asbestos-containing materials (ACM), implementation of asbestos hazard identification and abatement must include a rigorous operations and maintenance program. Control of asbestos exposure from in-place ACM is a public health priority.


Chronic liver injury in phenoxy herbicide-exposed Vietnam veterans.

Reports of hepatotoxic injury in Vietnam veterans exposed to phenoxy herbicides (mainly, 2,4-D and 2,4,5-T) initiated a retrospective cohort study of veterans self-reporting exposure to Agent Orange (AO) while serving in Vietnam from 1962 to 1971. Historical, medical, and laboratory information was obtained in a subcohort of 100 randomly selected veterans from a pool of 350 registrants. An occupational work exposure ranking system was designed to estimate individual exposure to phenoxy herbicide and its contaminant, dioxin (TCDD). Job classifications were determined by military job codes. Military application of the herbicides used in Vietnam were derived from the National Research Council Report based on the Herbs tapes. Health examination included tests of body systems affected by TCDD and similar agents, e.g., hemopoietic system, cholesterol/lipid metabolism, hepatic function, and skin lesions. Skin rash was utilized as a marker disease, since no case of true chloracne was found among the cohort. The cohort was divided into those with (R) and without (NR) a reported rash during or after the Vietnam tour. The R group had higher frequency (31%) of abnormal liver studies of all types than the NR group (18%). Of the 14 Vietnam veterans with persistent serum transaminase elevations, 86% reported a rash. Abnormal liver functions correlated with herbicide exposure index in both groups, but was more prominent in the R group. Study of the exposure index components showed that the liver abnormalities were related to the months of exposure and not to job classification or exposure rank. Viral hepatitis and alcoholism among both groups accounted for the association between liver abnormalities and cumulative exposure to AO. These data provide strong supportive evidence that chronic liver abnormalities among Vietnam veterans applying to the AO Registry are mainly due to viral or alcoholic causality and not to herbicides and their TCDD contaminant.


Fish consumption and reproductive outcomes in Green Bay, Wisconsin.

Prenatal exposure to polychlorinated biphenyls (PCBs) and reproductive outcome was determined in a population of 1112 women during 1987-1989. The women studied were from the Green Bay, Wisconsin area, thereby providing a population with potential PCB exposure from Lake Michigan sport fish consumption. All women with positive pregnancy tests from two Green Bay prenatal clinics were asked to complete a self-administered questionnaire on fish consumption, health and reproductive history, and other relevant issues and to provide blood samples for PCB analysis. A positive correlation was found between the amount of Lake Michigan fish mothers claimed to consume and their PCB serum levels. After the pregnancy period, reproductive outcome measures (fetal wastage; stillbirths; and birth weight, birth length, head circumference, ponderal index, and birth weight percentiles for live births) were abstracted from hospital labor reports. Typical negative associations between birth size measures and consumption of caffeine, smoking, and alcohol were found. Birth size was positively associated with gestational age, birth order, weight gain during pregnancy, male babies, and rural residence. Birth size was also associated with PCB exposure; however contrary to expectations, a positive association was found (P < 0.044) for most mothers (the exception being those mothers who gained more than 34 lb during their pregnancy). PCB exposures were lower than the other studies that found that birth size was negatively associated with PCB exposure.


Changes in PCB serum concentrations among capacitor manufacturing workers.

To assess the elimination of PCBs in humans, PCB concentrations in serum from 165 capacitor manufacturing workers were measured twice within a 46-month interval (March 1976-December 1979). Use of PCBs at the facility was entirely eliminated in 1977. PCB congeners with lower chlorination (LPCBs--mainly tri- and tetrachlorobiphenyls) had decreased in concentration, with six of the LPCB 7 peaks observed by packed column GC showing average reductions of 25-90%. Higher chlorinated PCBs did not decrease significantly as a whole, although three of the six constituent congener peaks showed some decline (15-25%). As expected, decreases in PCB congener concentrations were associated with chlorine substitution configurations known to be amenable to metabolism.


Neuropsychological performance among agricultural pesticide applicators.

To assess the potential effects on neuropsychiatric performance of chronic occupational exposure to organophosphate insecticides, we performed a prospective longitudinal study of a cohort of apple orchard pesticide applicators and a comparison cohort of beef slaughter-house workers. The study group consisted of 49 applicators and 40 comparison subjects who completed both an initial evaluation (preseason) prior to the onset of the approximately 6-month pesticide spraying season and a follow-up evaluation (postseason) about 1 month following the end of spraying season. The applicator cohort had a greater number (n = 22, 45%) of individuals who identified primary preference for Spanish-language testing than did the comparison cohort (n = 5, 13%). Stratification by language preference revealed no significant differences in background characteristics between the two cohorts, except for fewer years of education in the Spanish-language preference applicators versus control subgroups (5.0 +/- 3.1 vs 7.8 +/- 3.7 years, respectively). After controlling for language preference, there were no statistically significant differences between the applicators and control cohorts on neuropsychological subtests of the computerized test battery. Preseason baseline performance on individual tests was a significant predictor of postseason test performance. After controlling for baseline performance, the only statistically significant exposure related across-season changes in neuropsychological performance was for one subtest (Symbol Digit Substitution) and was confined to the Spanish language preference subgroups, with worse adjusted postseason performance among applicators versus controls (P = 0.001). This study found no clear evidence of clinically significant decrements in neuropsychological performance following one 6-month season of pesticide exposure in a cohort of applicators who were felt to have generally low, intermittent, and well-controlled organophosphate exposures.


Organophosphate pesticide exposure in a group of Washington State orchard applicators.

As part of a study to investigate the potential for organophosphates to cause chronic neurologic sequelae, we assessed the pesticide exposure experience of a group of Washington State apple orchard applicators. Seasonal monitoring of cholinesterase activity for 48 regular organophosphate applicators and a control group of 40 slaughterhouse workers was performed. A subset of the pesticide applicators participated in an in-depth exposure assessment. This involved observation of spraying activities during 1 spray day, as well as cholinesterase monitoring and dermal exposure assessment using a fluorescent tracer in the pesticide formulation. Comparison of seasonal red blood cell cholinesterase change in pesticide workers according to exposure level, characterized by frequency of pesticide spraying and protective equipment use, showed lower cholinesterase levels among higher exposed groups compared to lesser exposed groups. In-depth exposure assessment revealed exposure primarily on the head and hand regions. Subclinical changes (less than 15% inhibition) in red cell cholinesterase correlated well with dermal exposure calculations. This study suggests that cholinesterase monitoring may be a useful biological marker for even subclinical organophosphate pesticide effects.


Dangerous and cancer-causing properties of products and chemicals in the oil refining and petrochemical industry. VIII. Health effects of motor fuels: carcinogenicity of gasoline--scientific update.

1. Significant increases in tumors of kidney, liver, and other tissues and organs following exposure to gasoline provide sufficient evidence of carcinogenicity. 2. Benzene, a significant component of gasoline, has been established without question as a human carcinogen by IARC, EPA, and WHO. 3. 1,3-Butadiene, a component of gasoline, is a powerful carcinogen in both animals and humans. 4. Sufficient evidence for the carcinogenicity of alkyl benzenes, very significant components of gasoline, has also been established. 5. Human epidemiologic studies show important increases in cancers of the kidney, stomach, brain, pancreas, prostate, lung, and skin as well as hematopoietic and lymphatic leukemias as a result of exposure to gasoline, its components, and its vapors. 6. Stage 2 controls are being implemented to reduce exposure of the human population to gasoline vapors.


Morphologic, biochemical, and cytogenetic studies of bone marrow and circulating blood cells in painters exposed to ethylene glycol ethers.

In a previous cross-sectional survey, up to 15% of shipyard painters were found to have mild anemia or granulocytopenia, mostly acquired since employment. Environmental studies had suggested a possible etiologic role for ethylene glycol ethers, solvents to which the men were heavily exposed and which have established myelotoxic potential. To exclude alternative hypotheses, examine possible common patterns of injury, and identify potential risk factors and markers for such an effect, the affected painters were further studied. The painters were matched with two groups of controls: exposed painters without evidence of hematologic abnormality on the previous survey and unexposed controls. Altogether 25 subjects were studied by histopathologic examination of bone marrow, cytogenetic studies of marrow cells, and peripheral lymphocytes and peripheral red cell studies of membrane and metabolic function. Except for an unexpected finding of a race-associated effect on marrow histology, insignificant differences were seen among the groups in terms of marrow morphology and cellularity, stem cell growth kinetics, and marrow or peripheral cytogenetics. Two metabolic abnormalities of peripheral red cells related to exposure or clinical status of the subjects were found. Pyruvate kinase, an established marker of acquired myelodysplasia, was significantly depressed in the subjects with previously abnormal counts. Although reduced glutathione levels and holoenzyme activities of glutathione reductase (GSHR) did not differ among groups, exposed subjects had decreased saturation of GSHR with flavin adenine dinucleotide which could be restored in vitro, suggesting riboflavin deficiency or impaired riboflavin metabolism. Thus, although a unique pattern of bone marrow injury by histologic or genetic assay attributable to ethylene glycol ethers was not defined, biochemical effects of possible mechanistic importance were identified. The relevance of these findings as subclinical disease markers remains to be established.


Blood lead levels in incinerator workers.

Questions have been raised concerning the safety of mass burn incineration and its role in solid waste management. In 1989, the New York City Office of Occupational Safety and Health examined air levels of metals in New York City incinerators and found that workers were exposed to air lead levels as high as 2500 micrograms/m3 while cleaning the electrostatic precipitators in the plant. In order to determine the biologic significance of these exposures to the workers, blood samples were taken from 56 incinerator workers and 25 controls and analyzed for lead and erythrocyte protoporphyrin levels. Incinerator workers were found to have a mean blood lead of 11.0 micrograms/dl as compared to the control group level of 7.4 micrograms/dl. Risk factors for increased blood lead levels were analyzed using multiple regression analyses. Wearing a personal protective device "always" or not and the interaction of smoking and cleaning the precipitator more than seven times in the past year were found to be significant predictors for blood lead. These results indicate that lead in municipal incinerator ash from electrostatic precipitators is bioavailable and that the effects of such exposure can be minimized by wearing personal protective devices, not smoking, and rotating the work force to minimize precipitator ash contact.


A retrospective mortality cohort study of chrysotile asbestos products workers in Tianjin 1972-1987.

The mortality rate of a cohort of asbestos workers was investigated in Tianjin, China, between January 1, 1972, and December 31, 1987. The cohort consisted of 662 males and 510 females, employed in asbestos textiles, friction material, and asbestos cement manufacturing. A statistically significant excess mortality was observed for lung cancer in both males and females (SMR 278 and 427, respectively). An increasing trend in SMR was observed with increasing intervals of exposure as well as with increasing exposure level. A synergistic effect was seen between asbestos exposure and cigarette smoking regarding lung cancer. The ratio of smoking and nonsmoking lung cancer death rates was virtually the same in asbestos and in nonasbestos workers. This ratio was approximately 1.6, a value much less than that reported in other countries. This low ratio appears to reflect the fact that many nonsmokers were in fact passive cigarette smokers. Second, it reflects the fact that most smokers smoked hand-rolled tobacco, since manufactured cigarettes did not become popular in China until 1965. These data confirm the hazards of asbestos exposure in developing countries.


Comparative quantitative evaluation of pleural fibrosis and its effects on pulmonary function in two large asbestos-exposed occupational groups--insulators and sheet metal workers.

Two large (N = 1584 and N = 1330) population groups of workers exposed to asbestos as insulators (I) or sheet metal workers (SM) were compared. Prevalence rates of radiographic changes including pleural fibrosis (circumscribed and diffuse) were found to be much higher in I than SM. An integrative index of pleural fibrosis (INDEX) showed similar distribution patterns in the two groups; the effect of INDEX on FVC% predicted was more marked in insulators. Factors that could contribute to this difference are thought to be the higher prevalence of interstitial pulmonary fibrosis (probably including that which is not yet radiologically detectable) in I than in SM, the possibility of more extensive pleural fibrosis in areas not accessible to the standard chest X ray (and thus not affecting INDEX) and a higher proportion of diffuse pleural fibrosis in the I group.


Medical surveillance and screening in the workplace: complementary preventive strategies.

The terms medical surveillance and medical screening have sometimes been used interchangeably in the occupational medicine literature. Recently attempts have been made to redefine these as mutually exclusive, by nesting surveillance under screening or vice versa, by subsuming both under medical monitoring or periodic examinations, or by eliminating use of the term medical surveillance altogether. In this paper I argue that medical surveillance and medical screening represent discrete concepts and approaches and should be viewed as distinct and complementary secondary preventive components of an occupational health program. Medical surveillance refers to the periodic examination of putatively exposed workers, and is therefore a longitudinal approach. Medical screening refers to the cross-sectional testing or evaluation of a group of workers. Biological monitoring, whether defined narrowly or broadly, focuses on exposure to particular toxicants and should serve as a component of medical surveillance (or of medical screening), not as an independent complement to environmental monitoring. Medical surveillance must function in the context of a comprehensive occupational health program that includes industrial hygiene and education and does not in itself suffice as a comprehensive occupational health program. It is useful to clarify these terms because some of the ethical issues as well as medical controversies over their utility arise from a misunderstanding of what constitutes medical surveillance and how it should be applied.


Surveillance around hazardous waste sites: geographic information systems and reproductive outcomes.

The purpose of this paper is to discuss the potential for integrating surveillance techniques in reproductive epidemiology with geographic information system technology in order to identify populations at risk around hazardous waste sites. Environmental epidemiologic studies have had problems with estimating or measuring exposures to individuals, and of detecting effects when the exposure is low, but continuous. In addition, exposures around hazardous waste sites are complex and frequently involve chemical mixtures. The birth weight of human babies has been reported to be sensitive to many environmental influences. Birth weight can be analyzed as a continuous variable or as a dichotomous one using the standard cutpoint of 2500 g or less to indicate low birth weight. It has the potential to be a powerful surveillance tool since exposures to the fetus reflect maternal and paternal exposures. The advent of recent environmental regulations pertaining to hazardous waste sites has greatly increased the availability of environmental data for many sites. The major problem with incorporating these data into epidemiologic studies has been with the logistics of data management and analysis. Computer-assisted geographic information systems hold promise in providing capabilities needed to address the data management and analysis requirements for effective epidemiologic studies around to hazardous waste sites.


Sentinel pathophysiologic conditions: an adjunct to teaching occupational and environmental disease recognition and history taking.

Primary care physicians have an increasingly important role in identifying occupational and environmental (O/E) disease. However, the basic skills in O/E history taking, diagnosis, and management have not been adequately incorporated into traditional American medical education or practice. Reasons for these educational barriers are discussed. A new approach to O/E history taking, based on a modified list of occupational sentinel health events, is described. This list will give medical students and residents a practical, directed approach to recognizing O/E conditions and evaluating exposures in formulating a differential diagnosis. Through improved detection and assessment on the part of primary care physicians, appropriate referrals to occupational health specialists can be made for further investigation and public health surveillance.


Effect of zinc on lean tissue synthesis during recovery from malnutrition.

During recovery from severe wasting, malnourished children gain weight at greatly accelerated rates. To determine if additional zinc added to their basal therapeutic diets increased the retention of lean tissue and stimulated protein metabolism, we studied three groups of children taking either the basal diet alone or the basal diet supplemented with either 76 mumol (5 mg) or 153 mumol (10 mg) Zn/kg diet. The zinc-supplemented children gained similar weight and consumed the same amount of diet as the unsupplemented children. Zinc supplementation resulted in a greater net absorption of nitrogen and a higher rate of protein turnover, as estimated from urinary ammonia 15N enrichment after oral [15N]glycine. We conclude that additional zinc affected the composition of newly synthesized tissue and intermediary nitrogen metabolism.


Changing from a mixed diet to a Scandinavian vegetarian diet: effects on nutrient intake, food choice, meal pattern and cooking methods.

Twenty healthy, non-smoking, normal-weight omnivores volunteered for a nutrition counselling programme and changed from a mixed to a Scandinavian lactovegetarian diet. Dietary surveys were performed before and 3, 6 and 12 months after the dietary shift. The major trends when changing from a mixed diet to a lactovegetarian diet included an increase in the consumption of fruits, berries, vegetables, herbal tea and dairy products, and a decrease in the intake of biscuits and buns, sweets, alcoholic beverages, coffee and tea. There was a total absence of fish, eggs and meat products at 3 and 6 months after the dietary shift. At 12 months after the dietary shift two subjects ate small amounts of these animal products. The energy intake decreased throughout the study. The nutrient intake showed the greatest change between the period before and 3 months after the dietary shift. Between 3, 6 and 12 months after the dietary shift there were only minor changes. The observed change in meal pattern is associated with the change in consumption of various food items, the change in nutrient intake and the change in food preparation methods. Further studies should try to clarify the relationship between meal pattern and food intake, nutrient intake and food preparation methods, because counselling on meal pattern most certainly is more rapid and more easily understood than counselling on food and nutrient intake.


Reproducibility and validity of 7-day food records.

The reproducibility of the 7-day food record method, as used in The Glostrup Population Studies, has been tested by 40 adult volunteers, mainly hospital staff, recording their dietary intakes in two 7-day periods. To validate the calculated protein intake a 24-h urine specimen was collected from all participants in period II, but for various reasons urine specimens were only obtained from 31 in period I. There were significant differences in the intakes of energy, protein and some vitamins and minerals between the two periods, but the nutrient densities, except for vitamin A, were equal. The mean energy distributions in the diet showed no significant differences between the two periods. The weekly variance ratio (S2within/S2between) was between 0.25 and 0.80 for most nutrients. The only ratios above 1.0 were found for vitamin A, vitamin C, vitamin D, vitamin B12 and chromium, selenium and sodium. The weekly coefficients of variance (CV) were for most nutrients less than 30%. In period II the mean protein intake estimated from the urine samples was 74.7 (+/- 15.9 SD) g/day, whereas the protein intake calculated from the diet records was 70.6 (+/- 18.4) g/day. The average estimated protein intake for the 31 people who collected urine in period I was 72.1 (+/- 18.3) g/day, whereas the calculated intake was 78.0 (+/- 22.7) g/day. In neither period were the mean differences significant.


Who completes seven-day food records?

This study is an attempt to characterize a group of people who volunteered to complete 7-day food record forms. The group was an age- and sex-stratified random sample, comprising 4807 men and women, born in 1922, 1932, 1942 and 1952, drawn from the Civil Registration System. They all received an invitation to the Glostrup Population Studies in 1982-1984. A total of 49.2% completed a 7-day record form. The percentage of respondents was highest in the older age groups. Women were more willing to participate. There was no difference between the groups regarding body mass index. Marital status had some influence, but school education and vocational training had minor importance. A higher percentage of participants, who had never smoked or had quit smoking, completed the records. The male respondents had a lower weekly consumption of beer. No significant differences could be found between the dietary values of the respondents' and non-respondents' food consumption according to a food frequency questionnaire.


A seven-year follow-up of a weight reduction programme in Finnish primary health care.

The study was carried out to assess the short- and long-term effects of a Finnish Social Insurance Institution (SII) weight reduction programme in overweight primary health care clients and the suitability of the programme for use in health centres. The treatment group consisted of 22 men and 71 women, mean body mass index (BMI) 34.3, divided into 8 subgroups. These subjects participated in a 6-week weight reduction course led by public health nurses. Afterwards, there were six follow-up sessions and weight measurements at about 2-month intervals. A control group of 20 men and 76 women, mean BMI 33.5, received no weight reduction instruction during the 1 year that they served as controls. The weights, serum and high-density lipoprotein (HDL) cholesterol levels as well as blood pressures of the subjects in both groups were measured at entry to the study and at the end of the 1-year period. At that time the treatment group showed a weight reduction of 10.9 kg in men and 5.4 kg in women. The control group showed a mean weight gain of 0.9 kg in men and 0.2 kg in women. HDL cholesterol increased in the treatment group. The blood pressure decreased significantly in the category of subjects with a weight loss exceeding 4 kg weight. At the end of the 7-year follow-up period the mean weight reduction in the treatment group was 8.7 kg in men and 3.5 kg in women. Of men 53% and of women 21% still weighed over 10 kg less than at baseline. Both the clients and public health nurses found the weight reduction programme useful and applicable to health centres, preferably with extended time. The programme has now been adopted nationwide in the Finnish primary health care system.


Interpretation of erythrocyte glutathione reductase activation test values for assessing riboflavin status.

The erythrocyte glutathione reductase activation test (EGR-AC) is considered to be the best method to assess riboflavin nutritional status. Riboflavin supplementation studies carried out in India have raised doubts about the validity of currently available interpretive guidelines for interpreting the EGR-AC test. Changes in EGR-AC values in response to graded doses of riboflavin supplementation were investigated in schoolchildren, aged 7-11 years, belonging to the low-income group. For comparison, unsupplemented well-to-do schoolchildren of similar age group were also examined. The results of the study based on the measurement of EGR-AC by the procedure of Bayoumi and Rosalki (Clinical Chemistry, 1976, Vol. 22, pp. 327-335) with an incubation period of 15 min suggest that the cut-off value for EGR-AC to discriminate between riboflavin-deficient and normal children cannot be less than 1.5.


A comparison of four methods of estimating the body composition of male endurance athletes.

Comparisons were effected of the following four methods of estimating the percent body fat (%BF) of 12 highly trained male endurance athletes (mean +/- SD = 2.20 +/- 4.9 years, 176.8 +/- 5.9 cm 64.2 +/- 6.4 kg): underwater weighing (UWW), total body water (TBW), total body potassium (TBK) and dual-energy X-ray absorptiometry (DEXA). The DEXA mean of 6.8% BF was significantly less (P < 0.05) than those estimated via UWW: 9.7% BF; TBW: 10.6% BF (fat-free mass of FFM = 72.0% H2O); and TBK: 9.7% BF (FFM = 66.6 mmol K.kg-1). Nevertheless, the DEXA % BF correlated 0.746 and 0.737 (both P < 0.01) with those from UWW and TBW, respectively; these were the only correlation coefficients to attain statistical significance (P < or = 0.05). Despite the similar means for UWW, TBW and TBK, 12 of the 36 individual differences between these three methods ranged from 3.2 to 10.4% BF. A critical assumption of UWW, which is regarded by many as the criterion method for the estimation of % BF, is that the FFM has a density of 1.100 g.cm-3. Use of in vivo-measured TBW and bone mineral (via DEXA) for the computation of FFM densities for our subjects, while assuming that the two other components of the FFM (protein and non-bone mineral) remained constant, resulted in scores ranging from 1.09541 to 1.10246 g.cm-3 (mean +/- SD = 1.09881 +/- 0.00254 g.cm-3). FFM and % BF differences between use of a constant FFM density of 1.100 g.cm-3 and the individual values ranged from -1.02 to 0.57 kg (mean +/- SD = -0.28 +/- 0.60 kg) and from -0.9 to 1.7% BF (mean +/- SD = 0.5 +/- 0.9% BF), respectively. It may be concluded that with young male athletes: (1) use of constants based on normal male cadavers yielded similar group means for % BF determined by UWW, TBW and TBK but the DEXA % BF correlated significantly with those from UWW and TBW; and (2) in vivo measurements of individual differences in TBW and bone mineral support the use of conventional UWW for the estimation of % BF.


Predictors of weight reduction in obese children.

The characteristics of successful and unsuccessful weight losers were studied in 48 obese children (relative weight > 120%) aged 6-15 years who were treated for 1 year and observed for another. Successful weight loss was defined as a decrease in relative weight of > or = 0.8 in the standard deviation score (SDS) at the end of the study. Thirty-two children were treated intensively, 16 with individual counselling and 16 in group therapy, while the remaining 16 children were treated conventionally in a school health care setting. Three children dropped out of the study. In 2 years, the relative body weight decreased by 1.7 SDS in those who were successful weight losers (n = 21, 47%), but remained unchanged in those who had been unsuccessful (n = 24). At baseline there were no differences between the two groups. At 1 year, the successful weight losers had lower body weight (P < 0.05), less lean body mass (0.05) and lower fasting concentrations of circulating insulin (P < 0.01) than the unsuccessful children did. A decrease in mothers' body mass index (BMI) and in documented energy intake over the first year as well as energy intake at 1 year were significant predictors of success at 2 years. The combination of these three predictors resulted in correct classification of about 3/4 of the cases as successful or unsuccessful weight losers. It appears, however, difficult to develop a clinically useful model for predicting the treatment outcome in obese children.


Diet of adults living in houses in multiple occupation.

This study describes the diet and lifestyle of people living in houses in multiple occupation (HMO). A census was taken from a random sample of 400 HMOs in Southampton. Interviews were carried out with a random sample of 73 adult residents from the HMOs. A group of 34 people recently rehoused by the local council were interviewed for comparison. The HMO group had a lack of adequate cooking facilities compared to the council group. A kitchen was used to cook a meal every day by only 53% of the HMO and 77% of the council group. The HMO group spent more money on rent and food than the council group. Women in the HMO group had lower intakes of protein, fat and calcium than women in the council group. Housing conditions appeared to have some influence on nutrient intake. However, the HMO and council groups behaved in a similar way for a number of dietary habits. In low-income groups such as those studied here, factors other than housing conditions appear to influence food intake.


Blood vitamin and lipid levels in overweight and obese women.

The study was carried out on 102 obese and overweight women, average age 41.5 years, and 33 control non-obese women matched for age. Fasting venous blood vitamins (ascorbic acid, tocopherol, retinol, carotenes, thiamin, riboflavin, folic acid, pyridoxine), lipids (total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, total lipids) and haematological indices were determined. Significantly lower serum antioxidant vitamin levels and a higher prevalence of vitamin deficiency were found in the study group. The study confirmed the high risk of dyslipoproteinaemia and the high frequency of elevated blood pressure in obese women. A correlation between ascorbic acid status, degree of obesity and the incidence of elevated blood pressure was demonstrated.


Accuracy of a quantitative food frequency questionnaire applied in elderly Norwegian women.

The accuracy (reproducibility and relative validity) of a self-administered quantitative food frequency questionnaire including 180 food items was evaluated. A total of 38 elderly women kept multiple weighed diet records for a total of 14 days over a 6-week period and filled in the questionnaire both before and after this period. Spearman rank correlations between the nutrient intakes from the two questionnaires varied from 0.43 for carbohydrate to 0.88 for energy percentage from alcohol. The median correlation was 0.70. Seven women whose recorded average energy intake was less than 1.17 times their measured basal metabolic rate were excluded from the analysis comparing the questionnaire and the diet records. The first questionnaire gave on the average 10% higher nutrient median values than the records, while the second questionnaire did not in general produce higher values. Unadjusted correlation coefficients comparing intakes measured by the two methods ranged from 0.31 for vitamin C to 0.79 for energy percentage from carbohydrate, the median coefficient being 0.61. On the average 77% of the subjects were classified in the same (+/- 1) quintile in the first food frequency questionnaire and the diet records. The present study indicates that the self-administered quantitative food frequency questionnaire is useful for measuring individual or group intakes for a variety of nutrients.


Platelet phospholipid fatty acid composition and function in vegans compared with age- and sex-matched omnivore controls.

Platelet function and phospholipid composition, plasma lipids and dietary intakes were assessed in 20 vegan subjects and 20 age- and sex-matched omnivore controls. The intakes of saturated fat were lower in the vegans and those of linoleic and linolenic acids were greater. Eicosapentaenoic and docosahexaenoic acids were absent from the diets of the vegans. Plasma total cholesterol and low-density lipoprotein concentrations were lower in the male vegan subjects and those of carotene were greater compared with their controls. The platelet phospholipids of the vegans contained higher proportions of linoleic (18:2n-6) and adrenic (22:4n-6) acids and lower proportions of arachidonic (20:4n-6), eicosapentaenoic (20:5n-3), docosapentaenoic (22:5n-3) and docosahexaenoic (22:6n-3) acids. Template bleeding times, platelet aggregation induced by adenosine diphosphate, compound U44619 and collagen were similar in both groups.


Decreased food intake in children with severe dysentery due to Shigella dysenteriae 1 infection.

Factors that affect food intake in acute shigellosis were studied in 82 children aged 24-59 months. Children were offered an energy-dense milk-cereal-oil-based diet every 2 h. Food intake was compared between children with Shigella dysenteriae 1 infection and those infected with other Shigella spp (predominantly S. flexneri). Mean energy intake in the first 48 h was 435 kJ/kg.d in children infected with S. dysenteriae 1 and 536 kJ/kg.d in children infected with other Shigella spp (P < 0.001). Febrile children ate significantly (P < 0.05) less food than afebrile ones (469 vs 517 kJ/kg.d). Food intake remained significantly (P < 0.001) less in children infected with S. dysenteriae 1 after controlling for the effect of fever. The results show that food intake is significantly reduced in dysentery due to S. dysenteriae 1 infection compared to that of other Shigella species; however, adequate calorie intake can be maintained by providing frequent energy-dense meals despite anorexia, fever, abdominal pain and diarrhoea.


Are we pushing the limits of public health interventions for smoking cessation?

The phenomenon of smoking cessation that takes place outside formal programs, which serve a small proportion of smokers, is an important public health issue. Self-help strategies represent an approach to potentially cost-effective smoking intervention that can be conveniently used by large groups of smokers. In this issue of Health Psychology, Gritz, Berman, Bastani, and Wu (1992) demonstrate that the mailing of self-help smoking cessation materials to nonvolunteer women in a health maintenance organization, without any personal contact, produces little behavior change beyond what occurs in the environment without such distribution. This outcome is not surprising and does not illiminate the possibility of efficacious use of self-help materials with a nonvolunteer population. An essential question is: Could these materials have been distributed in such a way as to increase their use and eventual efficacy? Efforts to attract more smokers to use existing materials are an essential element of self-help strategies. An effective public health approach is a comprehensive one that successfully engages the individual and, through multiple channels in the community, provides reinforcement, supports, and norms for not smoking.


A randomized trial of a self-help smoking cessation intervention in a nonvolunteer female population: testing the limits of the public health model.

Reaching nonvolunteer female smokers with effective smoking cessation programs is a critical public health challenge. Smokers (N = 2,786) among 15,004 female members of a health maintenance organization who completed a routine needs assessment were invited into the "UCLA Preventive Health Behavior Study," consisting of five telephone interviews over 2 years assessing health practices. Participants (N = 1,396) were randomized into experimental or control conditions of an unsolicited, mailed, self-help smoking cessation program. Subjects were not alerted to the link between the program and the health study. Smoking status was assessed at 1, 6, 12, and 18 months. Across all subjects, point prevalence at 18 months was 18.62, and continuous abstinence was 2.71%. No difference was found between treatment and control groups regarding smoking status or readiness to stop smoking--raising questions about the value of mailing cessation materials to nonvolunteers. Quit rates increased over the 18-month follow-up; those still smoking at 18 months reported increased readiness to quit. Predictors at each follow-up point were examined multivariately.


Smoking prevention among urban minority youth: assessing effects on outcome and mediating variables.

We tested the effectiveness of a social resistance/competence enhancement approach to smoking prevention among predominantly Hispanic seventh graders (N = 3,153) from 47 New York City schools. After blocking on school type (public and parochial) and ethnic composition (percent Hispanic), schools were randomly assigned either to receive the 15-session prevention program or to serve as no-contact controls. Using the school as the unit of analysis, significant program effects were found for cigarette smoking, normative expectations concerning peer and adult smoking, smoking prevalence knowledge, social acceptability knowledge, and knowledge of smoking consequences. Using structural modeling techniques, a significant relation was found between the normative expectation and knowledge variables affected by the intervention and posttest smoking, suggesting that changes on these variables mediated the impact of the intervention on cigarette smoking. This study extends the results of previous prevention research and demonstrates the generalizability of this approach to predominantly Hispanic urban minority students.


Self-disclosure of HIV infection: preliminary results from a sample of Hispanic men.

We examined self-disclosure of HIV infection among 101 seropositive Hispanic men residing in Los Angeles. Results indicated that disclosure was highly selective and presumably influenced by the social, psychological, and material consequences of informing others about one's medical condition. Subjects tended to inform significant others such as parents, friends, and lovers than less significant others such as employers, landlords, and religious leaders. There was a relatively high rate of disclosure (75%) to doctors/dentists who were not treating subjects for HIV infection. Gay and bisexual subjects (89% of the sample) were more inclined to disclose their HIV serostatus to homosexual or bisexual others than to heterosexuals and to inform those who were aware of their sexual orientation. Disclosure increased with severity of disease independently of length of time since testing seropositive. Self-rated negative changes in appearance correlated with disclosure to less significant others. The role of cultural attitudes and values in self-disclosure of HIV infection is discussed.


High school students' perceptions of AIDS risk: realistic appraisal or motivated denial?

We examined perceptions of risk for acquired immunodeficiency syndrome (AIDS) in 296 high school students living in or near a major urban center. We hypothesized that students with a dispositional tendency to deny threat would be more likely to misperceive their risk of contracting AIDS. Results indicated that study participants, overall, used their behaviors as a basis for assessing personal risk in the sense that they perceived higher risk when their behavior was in fact riskier. However, this relation did not hold for those students classified as repressors on a repression-sensitization scale; repressors' perceptions of absolute (but not comparative) risk were negatively correlated with degree of behavioral risk. In a secondary analysis, perceived absolute risk was found to be a significant predictor of intention to change AIDS-risk behaviors. This study provides support for a motivational interpretation of perceived invulnerability and has implications for the development of models of health behavior change.


Influence of age, sex, and family on Type A and hostile attitudes and behaviors.

We describe the influence of age, sex, and family on Type A and hostility indices that have been related to rates of coronary heart disease (CHD). The sample consisted of 120 girls and 95 boys (ages 6 to 18 years) and 141 women and 120 men (ages 31 to 62 years) from 142 families residing in an upper middle class community. Results showed little familial aggregation of Type A and hostility. Adults had higher Structured Interview (SI) Potential for Hostility ratings than did children, whereas children had higher Minnesota Multiphasic Personality Inventory (MMPI)-derived Hostility scores and SI Anger-In ratings than did adults. Male adults and male children had higher SI Potential for Hostility ratings and MMPI-derived Hostility scores than did their female counterparts. The heightened hostility of males may account, in part, for their heightened risk of CHD relative to females'.


Improving adherence to fluid restrictions in male hemodialysis patients: a comparison of cognitive and behavioral approaches.

A cognitive intervention and a behavioral intervention were compared to determine their relative effectiveness in reducing interdialytic weight gain (IWG) among eight adult male hemodialysis patients. The behavioral model consisted of positive reinforcement, shaping, and self-monitoring. The cognitive model consisted of a counseling intervention designed to modify health beliefs. Three small-sample experimental studies showed that both interventions produced immediate reductions in IWG. However, the behavioral intervention was superior to the cognitive intervention in producing maintenance of reduced weight gain. Combining the interventions resulted in no improvement over the behavioral intervention alone. Continuation of self-monitoring procedures produced maintenance of improvements up to 2 months posttreatment. Repeated-measures analysis of variance showed changes for only the "barriers" dimension of the health belief model (Hartman & Becker, 1978) (p < .001), and this occurred only following or concurrent with adherence behavior change. Suggestions for treatment and future research are offered.


Smoking cessation among self-quitters.

We examined cessation among 630 smokers who quit abruptly on their own. Continuous, complete abstinence rates were 33% at 2 days, 24% at 7 days, 22% at 14 days, 19% at 1 month, 11% at 3 months, 8% at 6 months postcessation, and 3% at 6 months with biochemical verification. Slipping (smoking an average of less than 1 cigarette/day) was common (9% to 15% of subjects) and was a strong predictor of relapse; however, 23% of long-term abstainers slipped at some point. These results challenge beliefs that most smokers can initially stop smoking and that most relapse occurs later on postcessation.


Hardiness: a review of theory and research.

Although a large body of research on hardiness (a personality construct with dimensions of commitment, control, and challenge) has accumulated, several fundamental issues remain unresolved. Although there are several hardiness scales, the properties of these scales have not been compared. There is debate as to whether hardiness is one or several characteristics. Research studying the pathways through which hardiness exerts its effects has not been comprehensively evaluated. Whereas critics have argued that hardiness does not buffer stress, others have suggested that hardiness buffers for working adults, for males, and in prospective analyses. There is also growing concern that hardiness is related to neuroticism. A review of the literature supports the following conclusions: The Dispositional Resilience Scale (DRS) has several advantages over alternative scales; DRS items form three factors that are consistent with hardiness theory; hardiness dimensions generally show low to moderate intercorrelations; the most common way of categorizing subjects as high or low in hardiness is not consistent with hardiness theory; hardiness does not buffer stress, and it does not buffer stress for working adults, for males, or in prospective analyses; both old and new hardiness scales inadvertently measure neuroticism. Recommendations for future research are provided.


Classification of crossed immunoelectrophoretic patterns using digital image processing and artificial neural networks.

A method is presented which makes it possible to present crossed immunoelectrophoretic patterns to an artificial neural network. The electrophoretic patterns are presented for the artificial neural network as three-dimensional vectors and it is shown that it is possible with this representation to train the network to learn the patterns and classify them. It was found that the ability to generalize was substantially increased by the addition of noise to the input patterns during training. Furthermore, the addition of noise decreased the number of presentations needed to reach the predetermined error level. The trained neural network was able to classify all distorted patterns correctly within an error range of 1%.


Electrophoretic study of conformational changes of a human soluble beta-D-galactoside-binding lectin upon storage.

Human brain lectin (HBL), a beta-galactoside specific soluble lectin, was purified by affinity chromatography. An alkylated derivative of this lectin was also prepared. Both native and modified molecules were conserved at -20 degrees C in the presence or absence of beta-mercaptoethanol, a reducing agent which was described to maintain the lectin activity in vitro or in the presence of beta-mercaptoethanol and lactose. The impact of storage conditions, over one year, on the native and derivated lectins, was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing and titration curve, using the PhastSystem (Pharmacia). Western-blot analysis using an anti-HBL antibody and size-exclusion high performance liquid chromatography were used to complete the study. The subunit M(r)s were estimated before freezing (T0) and after three and twelve months (T3, T12). They were comparable for all preparations. In all samples tested, isoelectric focusing demonstrated the existence of at least three acidic proteins, with the pI ranging between 4.7-4.9. Titration curves clearly showed pH-dependent conformational changes, resulting in a panel of differently charged molecular species, some of which may be related to different oxidative states of the cysteine residues. We concluded that lectin can be stored at -20 degrees C for at least one year before use as a reagent since the modifications revealed by electrophoretic analysis do not alter the hemagglutination activity and carbohydrate binding properties. The immunoreactivity also remained unchanged.


Purification of serum amyloid A and its isoforms from human plasma by hydrophobic interaction chromatography and preparative isoelectric focusing.

The present work was aimed at isolating human serum amyloid A, (SAA), an acute-phase protein mainly complexed to high density lipoproteins, directly from human plasma without sequential ultracentrifugation of lipoproteins and subsequent delipidation of the apolipoprotein moiety. Hydrophobic-interaction fast-protein liquid chromatography on Octylsepharose, using stepwise gradient elution profiles under dissociating conditions, followed by fast-protein liquid-gel permeation chromatography on a Superdex TM75 column revealed a higher than 95% purity of isolated SAA. Further purification of SAA from coeluting apolipoproteins C and A-II was achieved by preparative isoelectric focusing between pH5-7 using a Rotofor apparatus. Separation of the main SAA isoforms, SAA1 (pI 6.5) and SAA1 des-Arg (pI 6.0, lacking the N-terminal arginine), was achieved by anion-exchange fast-protein liquid chromatography on a Fractogel EMD DEAE 650-S column. The purity of the SAA1 and SAA1 des-Arg isoforms, thus isolated, was checked by immunochemical techniques and amino acid analysis. With the described method various SAA isoforms can be isolated, purified and separated directly from human plasma/serum without prior ultracentrifugation.


A comparison between low background silver diammine and silver nitrate protein stains.

Several methods of silver staining of proteins after sodium dodecyl sulfate-electrophoresis in polyacrylamide gels were compared. The most rapid methods were found to be less sensitive than more time-consuming methods. Among the long methods, those using glutaraldehyde treatment of the gel and silver diammine complex as the silvering agent were found to be the most sensitive, at the expense of the use of a modified polyacrylamide matrix and higher silver concentrations.


Two-dimensional electrophoretic analysis of immunoglobulin patterns in monoclonal gammopathies.

Two-dimensional (2-D) electrophoresis was performed on 24 serum samples from patients diagnosed with monoclonal gammopathies. These samples had been shown to have a homogeneous immunoglobulin (M component) by zone electrophoresis and immunofixation. Using 2-D electrophoresis, the nature of this aberrant protein was further analyzed. It has been presumed that the sharp, dark stained band identified by immunofixation was the production of a monoclonal immunoglobulin. The increased resolution afforded by 2-D methodology reveals several different patterns. On 2-D electrophoresis, a monoclonal antibody has a unique pattern. It consists of 3 to 6 strong, restricted heavy chain bands and a single distorted light chain spot. The 3-6 bands are microheterogeneity of the isoelectric point, attributed to posttranslational glycosylation and/or amidation/deamidation. Analysis by 2-D electrophoresis indicated only 5 samples with a true monoclonal pattern. All but 2 of the samples clearly had aberrant immunoglobulin, but interpretation of the pattern would suggest the protein is other than a fully synthesized monoclonal antibody. The samples showed the following: a monoclonal heavy chain pattern with multiple distorted light chain spots, only an aberrant light chain area, only an aberrant heavy chain, and only a polyclonal increase. Several IgG gammopathies had, in addition, concentrations of gamma heavy chain at a reduced size (34 kDa).


Rapid high resolution two-dimensional electrophoresis of human sperm proteins.

An improved protocol has been developed for two-dimensional gel analysis of human sperm proteins through the application of recent technical advances. Advantages of this protocol consist of increased resolving power, reduced processing time, enhanced reproducibility of staining patterns, and applicability to small quantities of protein. Technical improvements include determination of optimal protein loading (20 micrograms/gel), development of a reliable tube gel casting system, and application of minigel technology. In this study over 500 proteins were resolved with molecular weights ranging from 12,000 to 105,000 and isoelectric points from 5.0 to 8.5. This is a three-fold improvement in resolution over earlier results. A single operator was able to generate two-dimensional gels of multiple samples in less than one day. This rapid high resolution technique should facilitate further investigation of human sperm proteins under normal and pathologic conditions.


Two-dimensional electrophoresis of cat sera: protein identification by cross reacting antibodies against human serum proteins.

After two-dimensional electrophoresis of cat serum, individual proteins were identified by means of cross reacting antibodies against the human protein homologues. Testing by cross reactivities seemed the method of choice because immunoreagents for cat proteins are not easily available.


High resolution two-dimensional mapping of tissue-specific polypeptides in the desert locust, Schistocerca gregaria.

High resolution two-dimensional gel electrophoresis (2-DE) using immobilized pH gradients was used to map the tissue-specific polypeptides of the desert locust, Schistocerca gregaria. Highly specific comprehensive 2-DE reference maps ("master gels") were developed for the brain, corpus cardiacum, subesophageal ganglion, and hemolymph. The polypeptides were well resolved within the pH 4-7 range in the first dimension and within the 14-94 kDa molecular mass range in the second dimension.


Selective influencing of the migration time of SO4(2-) by forming neutral species with Pb2+ in capillary zone electrophoresis.

Organic and inorganic anions are analyzed using capillary zone electrophoresis with indirect fluorescence detection. As electrolyte 2,5-dihydroxybenzoic acid is used. By adding Pb2+ to the electrolyte the migration time of SO4(2-) can be selectively influenced and the separation of Cl- and SO4(2-) considerably improved. The fluorescence intensity of 2,5-dihydroxybenzoic acid increases in the presence of Pb2+ up to a concentration of 6*10(-4) mol/L Pb2+. Limits of detection in the lower mumol/L range were obtained.


Elimination of sample diffusion and lateral band spreading in isoelectric focusing employing ready-made immobilized pH gradient gels.

A simple procedure for the elimination of lateral sample as well as band spreading in precast, ready-made immobilized pH gradient gels is described. Round or rectangular holes are punched in the dry polyacrylamide gels prior to rehydration. The generated wells proved suitable for application of samples containing surfactants such as Nonidet P-40 or 3-[(3-cholamidopropyl) dimethylammonio]-1- propane-sulfonate (CHAPS). Lateral band spreading and precipitation of samples containing up to 9.5 M urea could be completely eliminated by this method.


Alteration of circadian rhythm in shift-working ambulance personnel. Monitoring of salivary cortisol rhythm.

In order to investigate the relationship between internal desynchronization and clinical intolerance to shift work, a set of circadian rhythms including salivary cortisol rhythm were monitored in seven shift-working ambulance personnel. Oral temperature, grip strength of both hands, subjective assessment of drowsiness, fatigue and attention were recorded approximately every four hours except during sleep, for seven days. Self-sampling of salivary cortisol, which was suitable evaluation of endocrine rhythm in field studies, was also tried in this study. cosinor (cosine curve fitting) method and power spectral analysis were used for time series data analysis. The internal desynchronizations between rhythms of physiological variables and sleep-wake cycle were observed in shift-working ambulance personnel. The incidence of internal desynchronization seemed to be higher in intolerant subjects, although the difference between tolerant and intolerant subjects did not reach a statistically significant level. The peak time of salivary cortisol rhythm during a twenty-four hour shift was phase-advanced as intolerant to shift work showed apparently an atypical circadian pattern of salivary cortisol with an abnormal peak at 21.00 h. In this subject, the clinical intolerance to shift work seemed to be associated with internal desynchronization of circadian rhythms. The present study confirmed the internal desynchronization of the circadian rhythm in physiological rhythms like oral temperature and grip strengths, and was in favour of the hypothesis of an internal desynchronization and clinical intolerance to shift work. The clinical implication of impairment of salivary cortisol rhythm remains to be further investigated.


Electromyographic fatigue in neck/shoulder muscles and endurance in women with repetitive work.

EMG was recorded with surface electrodes from the trapezius and deltoid muscles during a static endurance test at approximately 20% of maximal voluntary contraction. Objective parameters for localized muscular fatigue were derived from the time course of the root mean square (RMS) and mean power frequency (MPF) of the EMG recordings. Isotonic regression is introduced as a tool for assessment of such parameters. The most pronounced sign of fatigue for trapezius was an increase in the RMS values, while for deltoid it was a decrease in the MPF values. This could be explained by the different functions of the two muscles. The endurance time for a group of 11 women in industrial work with repetitive short-cycled work tasks who were diagnosed with neck/shoulder disorders (tension neck) was significantly shorter (p less than 0.05) than for a group with the same work, but without neck/shoulder disorders (n = 11), and shorter than for a control group (n = 11). Regarding the EMG fatigue measures, there were no significant differences between the three groups. We did not find any relationships between endurance time and the EMG parameters. The results indicate that neck/shoulder disorders were not associated with divergent mechanisms for developing fatigue in the muscles, as recorded with surface EMG.


Reducing back stress to nursing personnel: an ergonomic intervention in a nursing home.

A prospective epidemiologic study was conducted in two units (140 beds and 57 nursing assistants) of a nursing home to demonstrate the efficacy of an ergonomic intervention strategy to reduce back stress to nursing personnel. The total programme involved the following: determining patient handling tasks perceived to be most stressful by the nursing assistants (NAs); performing an ergonomic evaluation of these tasks; and conducting a laboratory study to select patient transferring devices perceived to produce less physical stress than existing manual patient-handling methods. The intervention phase included training NAs in the use of these devices, modifying toilets and shower rooms, and applying techniques to patient care. Immediately after completing the intervention programme, a post-intervention analysis (which lasted eight months in unit 1 and four months in unit 2) was performed. A biomechanical evaluation of the physical demands required to perform stressful patient-handling tasks showed that the mean compressive force on the L5/S1 disc, the mean hand force required to make a transfer, and the strength requirements (expressed as percentage female population capable) were 1964 N, 122 N, and 83% after intervention as compared to 4751 N, 312 N, and 41% before intervention. Subjectively, the mean rating of perceived exertion was less than 'very light' after intervention as compared to between 'somewhat hard' and 'hard' before intervention. Overall, the mean acceptability rates for the walking belt and the mechanical hoist were 81% and 87% for patient transfers. The incidence rate for back injuries prior to the intervention, 83 per 200,000 work-hours, decreased to 47 per 200,000 work-hours after the intervention. There were no injuries resulting in lost or restricted work days during the last four months of the post-intervention. It is concluded that an appropriate ergonomic intervention programme offers great promise in reducing physical stress and risk of low-back pain to nursing personnel. However, large-scale studies in different nursing homes are needed to confirm the above findings.


The effects of armrests and high seat heights on lower-limb joint load and muscular activity during sitting and rising.

The loading moment of force on the hip, knee, and ankle joints of nine healthy men rising from four different types of stools were compared, together with the levels of myoelectrical activity (EMG) in four leg muscles. Two types of stool (stand stools) had higher seats than a normal chair. The other two were of ordinary seat height, but one also had armrests. The bodyweight carried by the different stools when sitting was also measured, and the subject estimated the effort required for each trial. The mean maximum knee moment was over 60% lower when rising from the high stool than from 'ordinary' seat height. The difference between the high and low stand stool was also significant (p less than 0.001). Using the high stool or help of the arms reduced the mean maximum hip moment by about 50%. The mean maximum ankle moment was only marginally influenced by the different stools. Knee moment was influenced more by seat height than was hip moment. Vastus lateralis activity was significantly higher when subjects rose from 'ordinary' height than when rising from either stand stool (p less than 0.001). The rectus femoris muscle was little activated and the semitendinosus muscle was activated earlier when rising from higher seat heights. All subjects estimated the effort of rising from the higher stand stool to be lower than from the lower stand stool or from 'ordinary' height without arm rests. It was concluded that stand stools are good alternatives for workers who change frequently between sitting and standing work.


Anthropometry of south Indian industrial workmen.

This paper presents the results of an anthropometric survey conducted on South Indian male workers in the electronic industry. The data were collected as part of a project to modify work stations that utilized equipment from other countries. A set of 27 body dimensions were taken from a sample of 128 workmen (aged 18-35 years). The anthropometric measurements are compared with those of Indian men from Central, Western, and Northern parts of India and with those of the American, German, and Japanese men. The results indicate that in general the South Indian man is smaller than Central, Western, and Northern Indian men, as well as smaller than men in America, Germany, Japan, and Africa. This difference needs to be allowed for when considering buying and subsequently using imported equipment for the electronics industry in South India.


Structure of recombinant N-terminal globule of type VI collagen alpha 3 chain and its binding to heparin and hyaluronan.

A large portion of the N-terminal globule of human collagen VI was prepared from the culture medium of stably transfected human embryonic kidney cell clones. The recombinant product corresponds to sequence positions 1-1586 of the alpha 3 (VI) chain that consists of eight homologous approximately 200 residue motifs (N9 to N2) being similar to the A domain motif of von Willebrand factor. By ultracentrifugation fragment N9-N2 showed a molecular mass of 180 kDa and an asymmetric shape. Elongated structures that consist of eight small globes (diameter approximately 5 nm) were demonstrated by electron microscopy. The data indicate that each A domain motif represents a separate folding unit which are connected to each other by short protease-sensitive peptide segments. Circular dichroism studies demonstrated about 38% alpha helix, 14% beta sheets and 17% beta turns. Fragment N9-N2 showed binding to heparin which could be abolished by moderate salt concentrations. Heparin binding was assigned to domains N9, N6 and N3 which were obtained after partial proteolysis. Domains N7, N5 and N4 lacked affinity for heparin. In addition, N9-N2 showed strong binding to hyaluronan that required exposure to 6 M urea for full dissociation. Ligand binding studies indicated some affinity of N9-N2 for the triple helical region of collagen VI suggesting a role of the N-terminal globule in the self-assembly of microfibrils. No or only little binding was, however, observed to fibril-forming collagens I and III, several basement membrane proteins and other extracellular proteins. Fragment N9-N2 was also an inactive substrate for cell adhesion.


What limits affinity maturation of antibodies in Xenopus--the rate of somatic mutation or the ability to select mutants?

Although the Xenopus immunoglobulin heavy chain locus is structurally and functionally similar to mammalian IgH loci, Xenopus antibodies are limited in heterogeneity, and they mature only slightly in affinity during immune responses. During the antibody response of isogenic frogs to DNP-KLH, mu and upsilon cDNA sequences using elements of the VH1 family were cloned, sequenced and compared with germline counterparts. There were zero to four mutations per sequence, mostly single base substitutions, in the framework and CDRs 1 and 2 of VH. No mutations were found in JH. Since the point mutation rate was only 4- to 7-fold lower than that calculated for mice, affinity maturation does not seem to be limited by mutant availability. Because of a relatively low ratio of replacement to silent mutations in the CDRs and a very high ratio of GC to AT base pairs altered by mutation, it is suggested that the problem results from the absence of an effective mechanism for selecting mutants, which in turn might be related to the absence of germinal centers in Xenopus.


Emergence of committed B lymphoid progenitors in the developing chicken embryo.

The formation of B lymphoid restricted progenitors was followed during chicken embryonic development by monitoring the appearance of the various Ig gene rearrangements (DJH, VHDJH, V lambda J lambda), as a sensitivity that allows the detection of a single rearranged cell. By quantifying the DJH committed progenitor populations, we describe their evolution in different compartments at different developmental stages. The yolk sac is the first site where DJH-positive cells are observed (at days 5-6 of development); via the general circulation, they then seed the various organs while undergoing VHDJH and V lambda J lambda rearrangements, which occur simultaneously but lag behind DJH by one to several days. These progenitor populations decline with time in most lymphoid sites and only expand in the bursa. RAG-1 expression is observed in the bursa in the absence of ongoing rearrangement activity and thus appears to be an improper marker of rearrangement in the chicken. Commitment to the B cell lineage seems to result from an intrinsic cell program, but the survival and expansion of the committed B progenitors require the specific microenvironment of the bursa.


Hemin uptake system of Yersinia enterocolitica: similarities with other TonB-dependent systems in gram-negative bacteria.

The hemin receptor HemR of Yersinia enterocolitica was identified as a 78 kDa iron regulated outer membrane protein. Cells devoid of the HemR receptor as well as cells mutated in the tonB gene were unable to take up hemin as an iron source. The hemin uptake operon from Y. enterocolitica was cloned in Escherichia coli K12 and was shown to encode four proteins: HemP (6.5 kDa), HemR (78 kDa), HemS (42 kDa) and HemT (27 kDa). When expressed in E.coli hemA aroB, a plasmid carrying genes for HemP and HemR allowed growth on hemin as a porphyrin source. Presence of genes for HemP, HemR and HemS was necessary to allow E.coli hemA aroB cells to use hemin as an iron source. The nucleotide sequence of the hemR gene and its promoter region was determined and the amino acid sequence of the HemR receptor deduced. HemR has a signal peptide of 28 amino acids and a typical TonB box at its amino-terminus. Upstream of the first gene in the operon (hemP), a well conserved Fur box was found which is in accordance with the iron-regulated expression of HemR.


Reversible phosphorylation--dephosphorylation determines the localization of rab4 during the cell cycle.

The ras-like GTP binding protein rab4 is the only known rab protein on endosomes that is phosphorylated during mitosis. Since a large fraction of rab4 accumulates in the cytosol in mitotic cells, we investigated the molecular mechanism controlling membrane association of rab4. We first show that human rab4 is phosphorylated by recombinant mammalian p34cdc2 kinase in vitro. Next, the actual site of phosphorylation and its functional significance were determined using stably transfected CHO cell lines producing high levels of wild type rab4 or rab4 mutants bearing alterations at Ser196, which occurs within a consensus site for p34cdc2 kinase phosphorylation (S196PRR). Mutation of Ser196 to glutamine or aspartic acid completely prevented rab4 phosphorylation in mitotic cells and also blocked its appearance in the cytosol. Neither C-terminal isoprenylation nor carboxymethylation of rab4 was affected by the mutations or by phosphorylation. Finally, dephosphorylation and reassociation of soluble rab4 with membranes occurred upon exit of cells from mitosis. Thus, phosphorylation of Ser196 is directly responsible for the reversible translocation of rab4 into the cytosol of mitotic cells.