[Typical findings and erroneous findings in SPECT-radioimmunoscintigraphy using 99mTc-labeled CEA antibodies in colorectal tumors].

Radioimmunoscintigraphy with 99mTc-labelled monoclonal antibodies against Carcino-Embryonic-Antigen (CEA) is increasingly accepted in the follow-up of patients suffering from colorectal carcinomas. However, interpretation of transversal, coronal and sagittal reconstructions of "Single Photon Emission Computed Tomography" radioimmunoscintigraphic studies is difficult due to physiological antibody accumulations and anatomical based variations of antibody distribution. In the following study we demonstrate therefore, the typical findings and "pitfalls" of radioimmunoscintigraphy with 99mTc-labelled CEA antibodies in comparison to findings in computed tomography, to help to avoid misinterpretations.


[Radiologic diagnosis of osteoporosis. Current methods and outlook].

Osteoporosis is defined as a decrease in bone mass and structural changes in bone leading to an increase in fractures. Early diagnosis as quantification of prophylaxis and treatment are of great interest. A number of non-invasive techniques are available for measuring bone mass at multiple sites of the skeleton. This article reviews basic methodology and developments in radiography as in x-ray or gamma photon absorptiometry, quantitative computed tomography, ultrasound velocity and attenuation and magnetic resonance imaging. Clinical applications of these methods are discussed. The still experimental use of ultrasound and MRI in assessment of bone-mineral content may also give information on bone quality.


[Results of CT-guided puncture biopsies in the abdominal and pelvic regions].

Results of 285 abdominal and pelvic CT-monitored biopsies are presented. 81.6% of the histological biopsies (n = 46) were evaluable (39.1% right positive, 43.5% right negative, 4.35% suspect). In 13% no definite findings were made. For the cytologic examinations and those due to an abscess 44.8% led to a right positive diagnosis and 23.8% gave a true negative finding. In 4.2% of the cases a suspect finding was given. 28% of all cytological evaluations were not definite. The complication rate was 1%.


[The value of imaging techniques in the diagnosis of non-specific abdominal pain in young patients].

In a retrospective study the use of imaging modalities in the diagnosis of non-specific abdominal pain in patients under 31 years was evaluated. 253 patients with primarily non-specific abdominal complaints were analysed. For further investigation one of the following methods had to be applied: abdominal sonography and/or upper gastrointestinal tract roentgenograms and/or enteroclysis and/or barium enema. In 66% (167/253) of all cases abdominal pain remained non-specific. Clinical history and physical examination led to the final diagnosis in 66/86 (76.7%) of patients with pathologic findings. 21/561 (3.7%) radiographic examinations revealed abnormalities of clinical importance. In 10/253 (4%) patients the final diagnosis could be established only with the help of radiologic and/or endoscopic examinations. The low efficacy of conventional radiology justifies the demand for a stricter indication in the young patient suffering from non-specific abdominal pain.


[Acute abdomen caused by inflammation of a Meckel's diverticulum containing a stone].

Meckel's diverticula have a prevalence of approx. 2% in the population. About 90% of them are clinically inapparent. Usual complications are a perforation of ectopic gastric mucosa (possibly with intestinal bleeding), an invagination and a volvulus. Etiology is normally revealed only by surgical exploration. Calculi are rarely found in Meckel's diverticula, males being afflicted much more often than females. The enterolith consists of calcified residues of food. Unexplained abdominal symptoms with an ileus situation should also be considered a Meckel's diverticulum containing enteroliths. This is especially so, if there are unidentified calcifications visible on the abdominal X-ray.


Quality of life and antihypertensive drugs in the elderly.

Hypertension is common in the elderly with estimates of around 10-20% showing a sustained level of pressure, either systolic (greater than or equal to 160 mmHg), or diastolic (greater than or equal to 90 mmHg) or both. The benefits of treating subjects with raised diastolic pressure was shown by the trials of the European Working Party on High Blood Pressure in the Elderly (EWPHE), the Hypertension in Elderly Patients in Primary Care (HEP), and the Swedish Trial in Old patients with Hypertension (STOP-Hypertension). Evidence for the benefit of treating isolated systolic hypertension in the elderly was provided in one trial (SHEP: Systolic Hypertension in the Elderly Program), and the results of two others are awaited. However, it is important to provide data on all treatment effects, including adverse reactions as well as benefits. In addition to traditional measures of mortality, morbidity and side effects, the quality of life in patients on antihypertensive treatment should be considered. The methods of measuring quality of life in trials is discussed, and some results presented.


Accidents in the institutionalized elderly: injuries and consequences.

A total of 308 major and 519 minor accidents involving 588 patients occurred during one year at a somatic long-term care hospital and its associated nursing homes. In relation to the number of patients, the incidence of accidents was nearly three times higher in the nursing homes than in the hospital. The most prevalent injuries in female patients were fractures and hematomas, while open wounds were more frequent among male patients. Hip fractures were about as common in women as in men, while fractures of the extremities were three times more frequent in women. The majority of the accidents occurred during daytime, in the patient's room and in many cases soon after admission. Most of the injuries were caused by falls and in more than 90% no staff was present. Accidents were reported most frequently in October-December, and least often in July-September. Two thirds of the severely injured had to be transferred to an emergency hospital for surgery or other treatment. Patients who had had major accidents also had a higher mortality rate six months after the accidents as compared to a control group. The medical and functional consequences for the patients were considerable. Measures to reduce the number of accidents among geriatric patients are therefore urgently needed.


Plasma lactoferrin as a marker of infection in elderly individuals.

To assess lactoferrin as a marker of infection, plasma lactoferrin (LF) levels were determined in elderly in patients with infection and compared with age- and sex-matched healthy and hospital controls and young healthy blood donors. The median LF level in infection (800 ng/mL) was significantly higher than in healthy elderly living in old people's home (300 ng/mL) or elderly hospital controls (298 ng/mL) (p less than 0.01 in each case). Plasma LF correlated significantly with elastase alpha-1-proteinase inhibitor complex (EPIC) (Rs = 0.8, p less than 0.01) and C-reactive protein (CRP) (Rs = 0.45, p less than 0.02), but not with erythrocyte sedimentation rate (ESR) or white blood cell counts. We conclude that plasma LF, like CRP and EPIC, is a marker of infection in elderly individuals.


Orthostatic reactions in the 85-year olds.

Testing of the orthostatic reaction is recommended in the examination of elderly fallers. This test usually includes blood pressure and instantaneous heart rate measurement but is difficult to perform in very elderly people according to the guidelines suggested for younger subjects. One reason for this is that old people often stand up slowly. The use of a tilt table, which enables a rapid change in posture from recumbent to erect position, is tempting as it could provide a method for a better standardized test. To study the usefulness of the tilt table as well as the degree of orthostatic reaction in the very elderly, we examined a sample of 85-year olds who did not suffer from falls. All were tested both with the tilt table and with active rising. The drop in blood pressure was equal in the two test types, but the increase in heart rate was significantly larger in active rising. Many test subjects were afraid of the tilt table, and two developed cardiac arrhythmia, i.e., atrial fibrillation, during the test. In our opinion, active rising is the method of choice in old persons. While the test subjects were in unusually good health for their age and thus could provide a suitable reference group for this test, the systolic blood pressure dropped considerably in several during the test. Criteria and indexes developed for younger subjects are not useful, and different evaluation criteria should be developed for the very elderly.


Dietary intake in a group of independent-living old people in Oslo.

Dietary intake (24-h recall), dietary supplementation practice and relative weight (BMI) were investigated in a random sample of 257 independent-living elderly persons above 75 years. The proportion of energy from fat was unfavorably high among women (41.7%), while diet nutrient density was similar for men and women. Mean intakes of vitamin D, thiamin and iron were below recommended levels. Use of a dietary supplement was more common among women (66%) than men (48%). Average daily energy intakes of 6.3 +/- 2.1 MJ in women and 7.3 +/- 2.2 MJ in men were just below the lower limit of the reference interval. Overweight was uncommon, while 14% of the women and 4% of the men had BMI below 18.5 kg/m2; 2% had a BMI below 16. We conclude that low energy intake is the major reason for potential malnutrition in this group of elderly persons; up to 10% may be at risk for energy deficiency, while 2% were chronic energy deficient.


Age-related effects of ischemia, lidocaine and verapamil on overdrive-induced suppression of ventricular pacemakers in isolated rat heart.

The effect of age on ventricular automaticity in the isolated perfused rat heart was determined under different conditions. When the ventricle is electrically stimulated at a faster rate, drive cessation is followed by a temporary suppression of ventricular automaticity (overdrive suppression). The effects of ischemia, lidocaine and verapamil on overdrive suppression were studied in isolated perfused adult and senescent rat hearts with complete atrio-ventricular block, by monitoring ventricular escape rate and escape rhythm recovery time after 1 minute of overdrive at a constant multiple (x3) of the spontaneous rate. The results demonstrated that: 1) lidocaine decreases ventricular automaticity especially in senescent hearts; 2) verapamil does not modify ventricular automaticity in basal conditions in either adult or senescent hearts; 3) myocardial ischemia causes a reduction in ventricular automaticity and more markedly in senescent hearts; and 4) lidocaine exaggerates the effect of ischemia, while verapamil seems to antagonize its depressant effect more in adult than in senescent hearts.


Serotonin response in sweet-food craving Alzheimer's disease subjects.

Abnormal sweet-food craving may occur in subjects with Alzheimer's disease. This behavior may be due to abnormalities in the brain serotonin system. Fenfluramine stimulates the brain serotonin neurosystem, producing an increase in systemic prolactin. Using the fenfluramine stimulation test, brain serotonin system response was evaluated in 12 subjects with probable Alzheimer's disease. The subjects' caregivers completed questionnaires concerning subject food preferences and behaviors. Alzheimer's disease subjects with sweet-food craving were found to have a significantly higher response to fenfluramine than non sweet-food craving subjects. This preliminary study is limited by small sample size. Allowing for assumptions concerning central nervous system regulatory processes, the data suggest a possible role for the serotonin system in sweet-food craving in Alzheimer's disease.


Eosinophil activation and function in health and disease.

The emerging picture regarding the role of eosinophils in the immune response appears to be the following: IL-3 [in humans, (251)], and/or IL-1 [in the mouse system, (253)], then IL-5 and GM-CSF [which are secreted from activated T-cells at the inflammation sites or even from activated mast cells (346-348)] induce differentiation and proliferation of eosinophils in bone marrow. Other factors, such as PAF (303-309), C5a, soluble parasite products (259-261), or even IL-5 (139), serve as chemoattractants for eosinophils to the sites of allergic inflammation, usually around mucosal surfaces. Eosinophil survival and state of activation is enhanced by IL-5 (139). Eosinophils degranulate, thus releasing their toxic granule proteins by cross-linking Ig receptors, the most potent of which is sIgA, and the degranulation is enhanced by IL-5, IL-3, GM-CSF, and other factors or parasite products. Eosinophil degranulation can also be induced by complement, as well as PAF. The interplay of all these different mediators, and their effects on eosinophil function, is an integral part of the eosinophil's involvement in different disease conditions. Eosinophils appear to be involved in the pathophysiology of different diseases, in part, by releasing their toxic granule contents in tissues and causing tissue damage.


Physiological studies with human leukocyte inhibitory factor.

LIF has been shown to be a potentially important activator of neutrophil function. By means of its dose-dependent dichotomous effects on chemotaxis, LIF can be predicted to both enhance the potency of chemotactic stimuli and promote the passive accumulation of PMN at inflammatory loci. Furthermore, LIF's stimulatory effects on both PMN- and endothelial cell-mediated adherence will promote the migration of neutrophils from the circulation to the inflammatory site. We have demonstrated LIF stimulation of fMLP, CR1, and CR3 expression and function, as well a stimulated Fc gamma RIII function. Through both receptor-dependent and -independent effects. LIF produces increased target cell attachment, phagocytosis, respiratory burst activity, and degranulation. Together, these effects result in a significant increase in killing of both phagocytosed targets and extracellular targets.


Activation of neutrophils by interleukins-1 and -2 and tumor necrosis factors.

This review outlines evidence that IL-1, IL-2, and TNFs modulate neutrophil functions. These cytokines affect some or all of the following functions of the neutrophil: adherence, cell migration, respiratory burst, lysosomal enzyme release, and cell surface receptor expression. TNFs, especially TNF alpha, remains one of the most highly studied cytokine with respect to regulation of neutrophil function. TNFs are a direct stimuli for the neutrophil respiratory burst and weak stimuli of lysosomal enzyme release. The cytokines enhance cell adhesion and inhibit neutrophil migration. The TNFs augment the oxidative burst and lysosomal enzyme release response to a wide range of soluble and particulate cell stimuli. These changes in the cell seem to be closely correlated with the increased fungicidal, bactericidal, tumoricidal, and protozoacidal activity of the TNF-primed neutrophils. In contrast to TNFs, IL-1 and IL-2 inhibit neutrophil adherence, and this provides evidence that the cytokine family represents a regulatory system. Another form of regulation of TNF alpha and IL-1 neutrophil-activating activity is by the release of inhibitors to these cytokines (58). We have evidence which shows that the soluble TNF alpha inhibitor (a cleaved product of the TNF alpha receptor) (59) binds and inhibits TNF from activating and priming neutrophils (60). Priming of neutrophils by TNFs involves surface receptor binding but is independent of protein kinase C system, pertussis toxin-sensitive guanine nucleotide regulatory protein, and direct burst of respiratory activity. The translocation of cell surface receptors and constituents of the NADPH oxidase from stored vesicles may be the major mechanism of TNF-induced cell priming.


Activation of neutrophils by granulocyte-macrophage colony-stimulating factor.

A hypothetical pathway of GM-CSF-induced signaling in human neutrophils is presented in Figure 4. The earliest postreceptor events leading to activation of cellular kinases and phosphorylation of c-raf on tyrosine and serine remain a mystery. It is conceivable that downstream events such as the production of LTB4 and PAF as well as other autocrine or paracrine activators of neutrophil-activation function may be involved in neutrophil activation and priming, or they may be downstream events irrelevant in the signaling cascade. The association of GM-CSF signaling and G-proteins, PLD, c-raf, tyrosine kinases, and the Na+/H+ antiport remain poorly understood.


Mechanisms of host tissue damage by cytokine-activated neutrophils.

Although extensive investigations into the role of neutrophils and their products in tissue injury have been conducted, very little work has been carried out on the role of polypeptide cytokines in the regulation of neutrophil-mediated tissue damage. A range of cytokines are known to promote a wide variety of functions of the neutrophil, including neutrophil adhesion, surface receptor expression, ODRS production, and release of lysosomal constituents. Evidence has been presented to show that these products, either singly or in combination, cause tissue injury. At this stage, TNF alpha and TNF beta are cytokines which have been shown to regulate neutrophil tissue injury. From this work it is suggested that TNFs promote neutrophil-mediated tissue damage.


The prevalence of hairy leukoplakia in HIV seropositive and HIV seronegative immunocompromised patients.

The prevalence of hairy leukoplakia was determined among 176 symptomatic HIV seropositive patients seen at the outpatient department of the Institute of Tropical Medicine in Antwerp, Belgium. Moreover, systematic tongue biopsies were performed during postmortem examination of 21 patients with AIDS, 100 HIV seronegative immunocompromised patients with haematologic or other malignancies and 100 HIV seronegative non-immunocompromised patients who died at the University Hospital Antwerp. Hairy leukoplakia was observed in 52 (29.5%) of the outpatients, but only in one (5%) of the AIDS patients in the postmortem study (P = 0.03). An explanation for this difference may be that significantly more AIDS patients who died had received either acyclovir or ganciclovir during the 3 months prior to the postmortem examination than the HIV seropositive outpatients during the 3 months prior to examination. Hairy leukoplakia occurred more often in Caucasian homosexual men with HIV infection (38%) than among heterosexual Africans with HIV infection (17%) (P = 0.06). Hairy leukoplakia was observed in none of the HIV seronegative patients.


Sexual behaviour related to the spread of sexually transmitted diseases--a population-based survey.

Behavioural patterns pertinent to the spread of sexually transmitted diseases (STD) were assessed in a random sample population study in Sweden. From a sample of 1150 individuals aged 16-31 years, 768 (68%) completed a questionnaire on past and present sexual contacts. Response rate was highest in youngest and oldest age groups. Median age at first intercourse was 16.4 years for women and 17.1 years for men; the woman's partner at first intercourse was a median of 2 years older; men chose partners of the same age for first intercourse. The time to second partner was a median of 2 years; number of lifetime partners increased with one new partner for 2.5 years. Condoms were more frequently used in younger age groups. In all age groups, 5-10% of individuals reported a high-risk behaviour for the spread of STDs.


Eight year prospective study of HIV infection in a cohort of homosexual men--clinical progression, immunological and virological markers.

Three hundred and fourteen homosexual/bisexual men at risk for human immunodeficiency virus (HIV) infection (170 seroprevalent HIV-positive, 144 seronegative) were prospectively studied over 8 years to assess rates of HIV infection and disease progression, in conjunction with cellular and HIV serological markers. In HIV-positive subjects, CD4+ lymphocyte counts rose strikingly during the period surrounding seroconversion, then fell progressively over the intervening period to a mean level of 300 cells/mm3 when AIDS developed. Changes in CD8+ lymphocyte counts were less consistent. The trend for HIV serological markers over the study period was of progressive decline in the proportion of subjects with anti-p24 antibody, associated with an increase in the proportion of subjects with detectable HIV antigenaemia. However, only 45% of subjects tested had lost anti-p24 antibody by the time of AIDS diagnosis, and HIV antigen was detectable up to 4 years before this. Different HIV serological patterns were also observed in subjects presenting either with Kaposi's sarcoma or opportunist infections. Our data support the continued use of cellular and virological markers in the evaluation of HIV disease; however, the variability observed in this study highlights their limited ability in predicting specific clinical events. Care should therefore be taken to encompass both clinical and laboratory information in the medical assessment of the HIV-infected individual.


Trends in sexual behaviour in a cohort of homosexual men: a 7 year prospective study.

A cohort of homosexual men at risk for human immunodeficiency virus (HIV) infection were studied prospectively over a 7-year period (1982/88) to assess trends in sexual behaviour and amyl nitrite intake. During the period, there were dramatic declines in the proportion of HIV seropositive and seronegative subjects reporting multiple casual partners for anal intercourse, unprotected anal intercourse and recreational use of amyl nitrite. Reported rates of orogenital intercourse remained the same during the period, whilst the total number of seroconversions fell from 17 for the period 1982-84 to 8 for 1985-88. High-risk sexual and related social behaviour among homosexual men, as assessed by patterns of anal intercourse behaviour and nitrite intake, changed over the 7-year period, with the greatest changes apparent before the widespread availability of HIV antibody testing and public education campaigns. This highlights the effectiveness of peer-group and community-based programmes in modifying the sexual behaviour of their members.


Megestrol acetate vs cyproheptadine in the treatment of weight loss associated with HIV infection.

Two appetite stimulants, megestrol acetate and cyproheptadine were administered in a randomized trial to 14 patients who had no evidence of opportunistic infection or malabsorption but were wasted (had lost more than 5 kg body weight) as a result of human immunodeficiency virus (HIV) infection. Energy intakes were calculated from a 7 day weighed dietary record. Mean energy intakes per kilogramme body weight were similar in both treatment groups (greater than 34 kcal/kg) and were higher than that in well British males. Energy intakes increased by just over 500 kcal during both treatments, but fell to pretreatment levels after therapy. Patients in both treatment groups gained a moderate amount of weight. Megestrol acetate was associated with impotence in 4 patients. Insufficient calorie intake alone is not a common cause of wasting associated with HIV and the role of appetite stimulants is likely to be limited.


Strain characteristics and antibiotic susceptibility of isolates of Neisseria gonorrhoeae causing disseminated gonococcal infection in Australia. Members of the Australian Gonococcal Surveillance Programme.

The auxotype (A) and serovar (S) distribution and antibiotic and serum sensitivity of 22 strains of Neisseria gonorrhoeae isolated from blood and joints were determined. With one exception, these strains from disseminated gonococcal infections (DGI) belonged to one of 4 serovars of the IA serogroup and were resistant to killing by normal human serum. The auxotype distribution of these Australian strains differed significantly from that reported elsewhere in that 17 of the 22 isolates were proline requires, but none were of the AHU auxotype. This lack of the AHU auxotype in the DGI strains in Australia was explained by the virtual absence of AHU requirers in a sample of 1560 mucosal strains isolated in Sydney and Darwin from 1987 to 1990. The A/S distribution of these mucosal isolates also helped to account for the low (0.12) percentage of DGI strains in isolates examined by the Australian Gonococcal Surveillance Programme (AGSP) from 1981 to 1991, and the differences in the rates of DGI in Sydney (0.08%) and Darwin (0.87%). There was a relative lack of the IA serogroup strains which are mostly responsible for DGI in the mucosal isolates from Sydney (15% of all strains) but a higher proportion of these serovars (40%) in the Darwin sample. There were 46 cases of DGI in data from the AGSP, 29 of these being women. Seven of the cases diagnosed in Australia were infected with penicillinase-producing gonococci suggesting that antibiotics other than the penicillins should now be used for this condition in this region.


Prevalence of HIV-2 infection in a family planning clinic in Lisbon.

A significant proportion (10%) of notified AIDS cases in Portugal are due to HIV-2 infection as a result of the close connections of Portugal with Western African Countries (ex-Portuguese colonies) where there is a high HIV-2 seroprevalence. We conducted a seroepidemiological study of HIV-1 and HIV-2 infection in 1400 women attending family planning and antenatal clinics in a health centre in Lisbon with the objective of analysing whether there was evidence of HIV-2 spread in this population. The seroprevalence for HIV, as determined by ELISA and confirmed by Western Blot, was 0.42% (6 cases) and 50% of these were of HIV-2 infection. Analysis of the epidemiological inquiries reveals that out of the 6 seropositive cases, only one was a drug addict (HIV-1) and another a western African black woman (HIV-2). The other 4 cases (2 HIV-2 and 2 HIV-1) were white Portuguese women with no history of travelling to Africa or previous blood transfusions, and the only risk factor was a history of multiple sexual partners (in 3 out of 4).


Empirically treated Pneumocystis carinii pneumonia in London, 1983-1989.

For 227 episodes of Pneumocystis carinii pneumonia (PCP) treated at St Mary's between 1983 and 1989, factors predictive of fatal outcome were age, haemoglobin levels, peripheral lymphocyte count and alveolar-arterial oxygen gradient. Case fatality for the 47 empirically-treated episodes was significantly higher compared with the 180 cytologically proven episodes (55% vs 18%, chi 2 = 25.7, P less than 0.0001). Case fatality for episodes which could not be bronchoscoped was significantly higher compared with bronchoscopy negative cases (66% vs 25%, chi 2 = 4.5, P less than 0.05). Predictive factors for fatal outcome differed significantly for cases which could not be bronchoscoped and cytologically proven cases: haemoglobin level (10.7 g/dl vs 12.0 g/dl, P less than 0.001), lymphocyte count (0.64 x 10(9)/l vs 0.87 x 10(9)/l, P = 0.05) and oxygen gradient (77.7 mmHg vs 58.9 mmHg, P less than 0.02). Such differences were not observed between bronchoscopy negative and cytologically proven cases. Case fatality decreased significantly over time (b = -0.39, SE = 0.14, P less than 0.05). Total and non-fatal first time episodes displayed an inverse relationship between oxygen gradient and time (r = -0.22, P less than 0.006 and r = -0.24, P less than 0.01, respectively). Mean oxygen gradient of fatal episodes for sequential years increased significantly from 73 mmHg in 1983 to 102 mmHg in 1989 (r = 0.92, P less than 0.01). This suggests that medical intervention as well as presentation with less severe disease both contributed to improved case fatality over time.


Reduction in needle sharing among community wide samples of injecting drug users.

Evidence of reduced levels of needle sharing among injecting drug users (IDUs) has largely been confined to IDUs attending needle exchanges or receiving treatment. In this paper we present the results of a serial cross-sectional study of needle sharing conducted in Glasgow using a multisite sampling strategy. Of the estimated 9400 IDUs in the city, 503 were interviewed in 1990 and 535 in 1991. The proportion of IDUs reporting injecting with, or passing on used needles and syringes in the last 6 months fell significantly as did the number of individuals from whom equipment was received or passed on to. The impact of this level of sharing has been limited in terms of HIV transmission; the prevalence of HIV among the 1990 sample was 2.0% and 1.1% for the 1991 sample. However, the fact that third of IDUs in Glasgow continue to inject, even occasionally, with used equipment gives cause for concern in view of the other pathologies known to be associated with poor injecting hygiene.


Alcohol policy considerations for Indian reservations and bordertown communities.

For some topics, particularly in public health, summaries are dangerous because they may create the idea that a single or simple solution exists. This topic is one where a summary can create a false expectation of simplicity. There is no simple or easy solution to the problem of alcohol abuse in any community, especially reservation and bordertown communities in the western United States. The solution is complex, it must be comprehensive, and it will take a great deal of effort over time to reduce alcohol and substance abuse in any individual community. Indian communities must develop a comprehensive, consistent, and clearly defined alcohol prevention/intervention policy. Such a policy must utilize a systematic, public health approach that considers the physical, mental, and social well being of each and every individual within the region. It must address all types of problematic alcohol consumption, from sporadic alcohol consumption (light and heavy) to regular alcohol abuse and chronic alcoholism, for the problems found in Indian and bordertown communities arise from a variety of different drinking patterns. Presented in this paper are a large number of policy and prevention options that have been used successfully in human societies in various parts of the world and in the United States. The intent of the paper is to present and describe the variety of options for addressing alcohol problems that have been found to be of value in the control and reduction of alcohol abuse and related problems. The three broad categories of approach are: controlling the supply of alcoholic beverages through statute and regulation; shaping drinking practices directly; and reducing the physical and social environmental risks. Indian tribal councils and Native communities can, if they so desire, consider, debate, and enact any or all of these measures. The important issue is that they should be aware of these ideas for prevention and consider them carefully. If the preventive measures described here can be applied systematically and reasonably within the social and cultural contexts of a Native community, then the ultimate result should be positive. Readers are encouraged to read this paper carefully, to study the tables and figures, and if more detail is desired, to consult some of the many references found in the back. Comprehensive and positive alcohol policy has been ignored for too long in Indian country, and the resultant toll in morbidity, mortality, and suffering is too high. This paper presents the ingredients for a comprehensive policy. Each community need to work its own recipe.


Histochemical probing of potato periderm with neutral red: a sensitive cytofluorochrome for the hydrophobic domain of suberin.

A technique is described which uses the lipid fluorochrome neutral red as a cytochemical probe to detect the hydrophobic domain of the ligno-suberin matrix in native and wound periderm of potato tuber. Toluidine blue O is used as a counterstain to quench autofluorescence. The neutral red technique appears to be specific for the hydrophobic/lipid domain of suberin and is significantly more sensitive than Sudan III and IV. The fluorochrome was extensively used on paraffin-embedded tissue with excellent results but also worked on freehand sections of fresh periderm tissue. In tuber tissue undergoing wound-healing, the pattern of suberin fluorescence obtained with the neutral red probe was identical in specificity to the color pattern obtained with Sudan III/IV, but somewhat different than that observed when berberine was used. Results obtained with the neutral red probe and berberine probe visually demonstrated that during ligno-suberin biosynthesis, the depositions of hydrophobic/lipid and phenolic/lignin-like components in potato tuber periderm were separate processes. The deposition of these components does not necessarily require their simultaneous presence because the fluorescence from these probes showed that the components were not consistently present together on the cell walls.


Distinctive uptake of neutral red by mitotic cancer cells.

Neutral red stains both normal and cancer mitotic cells, but uptake by living mitotic cancer cells is distinctly higher than in normal cells. This new approach to cancer cell identification is demonstrated in 4 established tumorigenic cancer cell lines: human skin epidermoid carcinoma A431, mouse Cloudman malignant melanoma, human oral epidermoid carcinoma and rat hepatoma. Human Chang liver cells served as normal controls. With epidermal growth factor (EGF) prepulse, neutral red uptake is dramatically enhanced. The possibility of a causal relationship with M-phase specific phosphorylation is discussed.


A method for histological examination of undecalcified teeth.

A method is presented for histological examination of undecalcified ground sections of tooth roots affected with periodontal disease. The roots were placed in Karnovsky's fixative overnight, postfixed in 2% buffered osmic acid, and dehydrated in an ascending series of ethanol. The specimens were then infiltrated with propylene-oxide and Epon-Araldite resin, embedded in Epon-Araldite, and sections were prepared using a cutting and grinding system. The resulting ground sections were 8-12 microns thick. The sections were allowed to air dry at room temperature. When thoroughly dried, a coverglass was applied using resinous mounting medium DPX. The specimens were examined by phase-contrast microscopy. The method is useful for simultaneous examination of mineralized dental tissue and bacterial morphotypes covering the root surface of teeth involved with periodontal disease.


Macroscopic sectioning of undecalcified tissues.

An inexpensive laboratory apparatus designed to section undecalcified teeth and bone has been constructed. It consists of an electric motor with a mandrel bearing a carborundum sectioning disk centered within a Plexiglas enclosure. A coolant flows from a reservoir positioned in the upper portion of the Plexiglas enclosure to prevent desiccation or burning of the tissues. Undecalcified tissue can be cut into a series of thin, 0.5-1 mm slices to facilitate studies of pulpal enzymes, tooth morphology and design of dental cavity preparations.


[Alternative mechanical autotransfusion. Hemofiltration vs. hemoseparation].

The effect of haemoconcentration of shed blood from operative field during vascular surgery by either centrifugation (cell separation, n = 10) or haemofiltration (n = 10) was investigated. Interest in this in-vitro-study was focused on the quality of the blood concentrated. Various parameters were measured in the patient (before onset of anaesthesia), and in the blood after suction from operative field: 1. shed blood, 2./3. after haemoseparation/-filtration. Both procedures were easy to perform but haemofiltration produced whole blood quicker than the cell-separation technique (1.2:3.0 minutes). All patients had normal parameters. Suction led to an activation of plasma coagulation and an increase of free haemoglobin and elastase. Haemoseparation in contrast to filtration led to an elimination of thrombocytes, elastase, free hemoglobin and all proteins including antithrombin III and fibrinogen; concentration of red cells was more pronounced after separation (hct 55 vs. 35%). Heparin reduction was better after separation but plasma-heparin-levels were in a tolerable range after both procedures (0.21 vs. 0.75 U/ml). None of the procedures was followed by the appearance of activated clotting factors (F XII a). The data presented demonstrate that haemofiltration may be an alternative in intra- and postoperative autotransfusion. The particular advantage of this method is the preservation of plasma proteins after concentration procedure thus avoiding the need for additional application of fresh frozen plasma in patients with significant blood loss.


[Autologous transfusion--organization and results of preoperative blood donation by heart surgery patients].

This study presents our preoperative autologous blood donation programme that is in use since 1987. 246 patients of cardiothoracic surgery participated in this program. 77% of all patients had preoperative concentrations of haemoglobin above 12g/dl despite frequent donations. 36.5% of patients were transfused exclusively with their own blood products. Reduction of homologous blood transfusion has been achieved with second preoperative plasmaphereses and more restricted indication for blood transfusion. More blood donation could be performed with application of erythropoietin resulting in more frequent preoperative blood donations.


[The effect of blood conservation techniques on the plasma concentration and elimination of midazolam in patients undergoing hip joint surgery].

The question was to evaluate whether haemodilution or intraoperative autotransfusion have an influence on plasma levels and clearance of midazolam. The study was designed as a prospective evaluation of patients with total hip joint replacement. The patients received neuroleptanalgesia supplemented with enflurane. After induction of anaesthesia with midazolam (0.1 mg/kg body weight) haemodilution procedure was started. During surgery a cell saver was used for blood salvage. In the recovery room drainage blood was also being processed by a cell saver. The study includes 10 patients belonging to ASA-group II with an average weight of 79.4 kg (53-100 kg), at an average age of 57.9 years (44-68 years). Midazolam was measured in patient blood and in autologous blood units by gas chromatography. 151 micrograms of midazolam, i.e. 1.8% of the initial dose was retransfused in hemodilution blood. By processing of blood in the cell saver, 99.5% of the amount of midazolam found in the sample unit was eliminated. The maximum quantity was 5.5 micrograms in the washed autologous red cell concentrate. Considering the analytic limit of 2 micrograms/l of midazolam in plasma, retransfusion of autologous blood cannot influence the plasma concentration of midazolam. Therefore, there is no risk of re-sedation in retransfusing autologous blood postoperatively.


[Polytrauma following a fall from a great height. The injury pattern and the intensive medicine aspects].

We report on 10 polytraumatised patients who were treated in an ICU after a free-fall injury. The injury pattern of these patients proved to be relatively uniform. Brain oedema occurred in many victims. Remarkable was the fact that 8 out of 10 patients developed a pneumothorax, but only three of them had rib fractures on the same side. All patients suffered from fractures of the extremities with the lower extremities being affected more often. Abdominal injuries were not of importance.


[Checking the precision of capnometers].

Capnometry, i.e. measurement of CO2 concentration (cCO2, vol%) and calculation of the respective CO2 partial pressure (pCO2, mmHg), is simple to apply, but the user must understand its principles of operation in order to appreciate its power and its limitations. However, sidestream capnometers use to dry the humidified respired gas (37 degrees C, pH2O 47 mmHg) for methodological reasons, thus increasing pCO2 by ca. 6% which, in turn, requires correction. With infrared spectroscopy, overestimation of pCO2 in presence of N2O and underreporting of pCO2 in presence of O2 also require to be corrected. These require either knowledge of the respective gas concentrations (mainstream analyzers) or adequate (i.e. correct) measurement (some sidestream capnometers). Changes in barometric pressure (pB) must be also either known or be measured automatically. Evaluation of the precision of capnometers must therefore focus on, (1) the possible pH2O correction, (2) the possible effects exercised by O2 and N2O, and (3) the possible dependence on barometric pressure. Two mainstream (Capnolog D/Dräger; Sirecust 404-1/Siemens) and eight sidestream capnometers (AGM 1304/Brüel & Kjaer; SARAcap A. G. and SARA-trans/Biomedical Systems/Hellige; Capnomac and Normocap 200/Datex/Hoyer; CO2 Monitor/Dräger; Nellcor N-1000/Nellcor/Dräger; Multinex/Datascope) were investigated. Dry and humidified gases (37 degrees C) of defined composition in respect of CO2, O2, N2, N2O, and H2O, were used for evaluation. The results prove reproducibility of ca. =/- 1 mmHg for the 10 capnometers within the 30-50 mmHg pCO2 range.(ABSTRACT TRUNCATED AT 250 WORDS)


[Measurement artifacts in Gaeltec intracranial pressure monitors due to radio waves from personal beeper systems].

Artifacts were observed when using epidural pressure monitoring systems (Gaeltec ICT/B Titan). These were produced by radio waves from our beeper system. A non-existing electromagnetic shield of the Gaeltec-measuring amplifier SN 10/11 could be found as the cause. The artifacts can lead to therapeutical errors.


[A new single-lumen endobronchial tube for artificial respiration following pneumonectomy in thoracic surgery].

If a patient who has undergone a major resection such as a pneumonectomy or radical pneumonectomy develops during the postoperative period respiratory failure requiring mechanical ventilation, this may cause problems with the respirator treatment. It is of particular interest that the newly sutured bronchus stump can be protected from high ventilation pressures. Until now, patients who have undergone pneumonectomy have been ventilated using a single lumen tube or a double lumen tube (Table 1). A major complication often leading to death is a bronchial stump dehiscence giving rise to a bronchopleural fistula on the operated side due to aggressive mechanical ventilation. Therefore, we developed a new single lumen endobronchial tube (produced by Willy Rüsch AG, W-7050 Waiblingen, Germany, Cat.No. 115900) for the mechanical ventilation of pneumonectomised patients (Fig. 1). The sutured bronchial stump lies between the bronchial and tracheal cuff (Fig. 2) and for that reason is not exposed to any increased ventilation pressure. This new tube contributes to a lower complication rate in mechanically ventilated patients after pneumonectomy.


[Tubal malpositioning as a cause of tubal cuff hernia].

Airway obstruction of endotracheal tubes may occur during general anaesthesia. A case is reported where endobronchial intubation and inflation of the cuff caused herniation into the left bronchus before the malpositioning had been corrected. This led to a cuff herniation that caused airway obstruction at the end of anaesthesia. The regional overinflation of the tubes cuff could be reproduced by a model by other tubes of the same type. Malpositioning of endotracheal tubes may cause cuff herniation that potentially leads to acute airway obstruction.


[Clinical activity and serum immunoglobulin concentrations in patients with ankylosing spondylitis].

Several authors have suggested that immunoglobulin A plays a pathogenic role in ankylosing spondylitis. We have determined the levels of immunoglobulins in 30 patients, observing higher levels than in control patients (248 vs 176 mg/dl); p less than 0.01) and a relation between the increase of immunoglobulin A and the presence of clinical activity in the subgroup of patients B27-negative (163 vs 398 mg/dl, p less than 0.005), but not in B27-positive patients. We think that these e results support the hypothesis that ankylosing spondylitis is an heterogeneous disease, with different pathogenic mechanisms depending on the presence or absence of the serological marker HLA-B27.


[Intralymphatic administration of adoptive (LAK) immunotherapy in the treatment of patients with metastatic cancer resistant to conventional therapies].

Between January, 1990 and May, 1991, we administered LAK immunotherapy using the intralymphatic route to 25 patients with metastatic cancer resistant to conventional therapies. In the preparation of the immunotherapy, we followed the technique described by Pizza G. et al. The age of our patients ranged between 50 and 75 years and their Karnofsky's indexes were above 70%. The histological type of the metastasis were determined by Rx, ECO and/or CAT before and after the administration of the immunotherapy. In the intralymphatic administration, we followed the technique described by Pizza G. et al. The immunological therapy was administered on days 1, 21, 90 and 111 and the clinical response was assessed by RC, RP, EE and F. The immunological behaviour of the host was assessed through the determination of lymphoid populations (CD2, CD4, CD5 and CD8) and cytolytic cells were studied with monoclonal antibodies CD and CD16. Such immunological study was carried out before the administration of each immunotherapy series. In 7 out of 25 patients (28%), we were able to administer the four LAK series. Such patients were subsequently studied, observing that, although tumoral lesions did not increase in size, they did not disappear and, thus, they were classified as clinically stable. Clinical and analytical toxicity was null. The immunological study did not show any statistically significant changes and the activity of cytotoxic cells (NK) was not modified.


Real-time measurement of microvascular dimensions using digital cross-correlation image processing.

A real-time automatic digital image-processing algorithm was developed for measuring microvascular dimensions. Using video microscopic images of the vasculature, the video images are digitized and analyzed using contrast enhancement, frame averaging, and pattern recognition, rather than edge detection. Performance of the algorithm was evaluated for second- and third-order vessels surrounded by the complex interfering features of in vivo skeletal muscle. Graded diameter changes and vasomotion were induced with pharmacological agents. Data obtained by auto-tracking agreed with data obtained by traditional manual methods of measurement. These findings indicate that a pattern recognition algorithm based on cross-correlation analysis provides a highly accurate method for real-time automatic tracking of microvessel diameters.


Heme-containing proteins suppress lymphatic pumping.

Red blood cells (RBCs) and lysate products (erythrolysate) are consistently observed in lymph draining inflammatory reactions and from tissues subjected to trauma or surgical procedures. We determined previously that erythrolysate modulates lymphatic pumping by altering the pressures over which the lymph pump is active. The purpose of this study was to test the hypothesis that oxyhemoglobin was the active material within erythrolysate. To quantitate lymphatic pumping, bovine lymphatics were suspended in an organ bath preparation with the vessels cannulated at both inflow and outflow ends. By raising the heights of the Krebs reservoir and the outflow catheters appropriately, a transmural pressure could be applied to the vessels. This procedure stimulated pumping activity. Erythrolysate was prepared from sheep RBCs by lysis in Tris buffer and a portion of this was purified by column chromatography using DEAE-Sephadex A-50. Both the purified hemoglobin (10(-5) M) and crude erythrolysate (the latter diluted appropriately in Krebs solution to contain 10(-5) M hemoglobin) reduced lymphatic fluid pumping approximately 70% over a period of 2 h. To determine whether this activity was due to the heme or the protein portion of the molecule, we compared the activity of purified oxyhemoglobin with that of its oxidized methemoglobin derivative. This was achieved by conversion with potassium ferricyanide. Methemoglobin was inactive, suggesting that the heme portion was important for the lymphatic effect. Further confirmation of this observation was provided by experiments with myoglobin which was purified from sheep heart. Oxymyoglobin, which shares an identical heme but has a different protein component, inhibited lymphatic pumping, when tested on the bovine lymphatics.(ABSTRACT TRUNCATED AT 250 WORDS)


[Narcolepsy and alopecia areata: a new association?].

We here present three cases with Alopecia Areata and Narcolepsy, an association we believe to be hitherto undescribed. Narcolepsy is a low-frequency (0.5%) disorder. It is now accepted that the majority of patients with narcolepsy are DR2 positive. Alopecia Areata is a disease whose incidence in Caucasian population is between 0.05% and 1%. In both diseases there is a set of common data and the origins of the two diseases have been related to an autoimmunity mechanism. In both, a higher than normal incidence of diabetes has been recorded, together with a predominant HLA type pattern. We believe that this association is not casual although epidemiological studies are needed to test our working hypothesis.


[Incidence of typhoid fever in our environment. Analysis in Guipúzcoa].

Based in 184 cases of Typhoid Fever bacteriologically demonstrated in the past 14 years (greater than 90% of all cases registered in the whole province), we have observed that, with the exception of some epidemic outbreaks, the disease has been constantly present during all these years, with a higher incidence between August and November. Salmonella typhi infected primarily young adults, its distribution being similar to the one among the general population. 49% of cases were males. The estimated incidence rate of the disease during this period was 2-3 per 100,000 population. A seroepidemiological study among healthy women with ages between 20 and 40 years showed a seroprevalence of anti-H:d antibodies greater than or equal to 1/40 of 1%. Although the epidemiological situation of Typhoid fever in our environment is not as bad as it has been referred in reports and textbooks, an effort is needed to situate the problem at the appropriate level, given our geographical situation and our economical development.


Altered aortic production of 6-keto-prostaglandin F1 alpha from aldosterone-salt hypertensive rats.

Supersensitivity of vascular smooth muscle to catecholamines in aldosterone-salt hypertensive rats appears to reside beyond the alpha 1-adrenoceptor. The objective of this study was to assess the norepinephrine-stimulated production of arachidonic acid metabolites by aorta from control-salt rats (CSR) and aldosterone-salt hypertensive rats (AHR) to determine whether these metabolites might contribute to the altered sensitivity. Norepinephrine increased in a time-dependent manner the production of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) by the aortae of CSR. Production was an alpha 1-adrenoceptor-mediated event since it was inhibited greatly by prazosin but not by yohimbine. Basal values of the metabolites did not differ for 6-keto-PGF1 alpha and TXB2, but were higher in AHR compared with CSR for PGE2. The norepinephrine concentration-response curve for 6-keto-PGF1 alpha was shifted significantly to the right for the AHR group compared with CSR (EC50 = 2.30 +/- 0.55 and 0.29 +/- 0.07 microM, respectively) indicating decreased production of norepinephrine-stimulated prostaglandin I2 in AHR. The norepinephrine-stimulated TXB2 concentration-response curves for AHR and CSR were similar. Indomethacin was an effective inhibitor of TXB2 and 6-keto-PGF1 alpha production in both. Norepinephrine-stimulated contraction was significantly affected by indomethacin in CSR but not in AHR. Whereas we observed an attenuation of a norepinephrine-stimulated vasodilatory substance in aortae of AHR compared with CSR, the effect of attenuation on vascular activity is presently unclear.


[Non-specific digestive ulcers and Behçet's disease].

We present a 56-year-old patient with episodes of recurrent abdominal pain and constitutional syndrome, whose evolution was complicated by mucous ulcers in mouth, esophagus, anus and ileocecal valve, as well as occasional aphthae in scrotum. All these clinical signs are compatible with a Behçet's disease with relevant digestive manifestations.


[Tuberculosis caused by Mycobacterium bovis: apropos of 2 cases].

Infection by Mycobacterium bovis is currently a rare form of tuberculosis in developed countries, being its incidence lower than 1%. Its main mechanism of transmission is through the ingestion of contaminated milk. In this paper, two cases of tuberculosis by Mycobacterium bovis are described, one of lymphatic location by endogenous reactivation and another of pulmonary location, probably by a primary infection acquired through the inhalation route. We stress the risk of transmission of the disease through the respiratory route from infected animals and by person to person contagion.


[Previous dissociative psychiatric disorder and status epilepticus in a case of acute HIV infection].

We described an 18 old homosexual man who after 5 days developed a neurologic picture associated with Human Immunodeficiency Viruses (HIV) seroconversion. The patient had developed a dissociative psychiatric disorder 6 months before, and after resolution of the acute neurologic disease a mild neuro-psychiatric disorder remained. After mononucleosis-like syndrome of three weeks, the patient developed a meningo-encephalitic process 48 h post admission. He evolved with tonic seizures and twilight state and was admitted into Intensive Care Unit because of epileptic status and deep coma. Evolution was favourable after 72 h of treatment with acyclovir and antiepileptic drugs. Laboratory data showed an inverted T4/T8 ratio and seroconversion to HIV-antibodies and p24-antigen both in serum and CSF. These observations confirm the existence of psychiatric as well neurological alterations in acute HIV infection, and also the significance of p24-antigen and Western-Blot in serum and CSF in showing the seroconversion profile.


[Magnesium: therapeutic usefulness in emergency situations].

Magnesium has been a forgotten cation from the therapeutical point of view, given that, although its properties began to be known more than a century ago, its use has been always empirical or isolated. With respect to its use in emergency situations, in addition to correcting its deficit and using it for the treatment of hypercalcemia and hypopotassemia, it is currently recommended as the therapy of choice for the treatment and prevention of several arrhythmias. It can also be used to prevent its deficit, when such deficit is pathological or associated to the ingestion or certain drugs. Given the multiple properties of magnesium, controlled studies are required in order to define its potential therapeutical applications.


[The motives for consultation and the clinical stages of HIV-positive patients attending a health center].

To find the clinical condition and motives for consultation of HIV + patients seen in our Health Centre. This was an observational and retrospective study. SITE. The study was carried out in the Primary Care context, in the Natahoyo Health Centre (Gijón). The clinical histories of 26 HIV + patients registered at the Health Centre were studied. These supposed a total of 387 consultations from the day they were diagnosed as seropositive to the 31 August, 1991, or until their death. The 387 consultations recorded broke down into a average of 14.8 consultations per patient (SD 12.7). 43% due to a request for detoxification. Only 5.5% of patients were referred to the second level. In line with the classifications of the W.H.O., 14 patients (56%) would be in stage I; 3 (12%) in stage II; 3 (12%) in stage III; and 5 (20%) in stage IV. HIV + patients often attend our Health Centre, but mainly for bureaucratic reasons. Consultations due to illness tend to be for minor pathologies, which are almost always treated successfully in the Centre itself. The WHO's classifications were found to be useful for assessing the stage of each HIV + patient at the Primary Care level.


[Urinary infections. Outpatient antibiotic sensitivity in the province of Girona].

To discover the level of autochthonous urinary microflora and their sensitivity to antimicrobials, at the primary care level. A descriptive and retrospective study of a sequential sampling of urine cultures in primary care (during July, August and September, 1991). SITE. Primary care in the Province of Girona. 700 individuals between one month and 91 years, with positive urine cultures. 19% men, 68% women, 13% not specified. 76% of the urine cultures studied contained E. coli. The proportion of Proteus and Pseudomonas is higher in the pediatric group. We detected a low sensitivity in those with urinary pathologies to ampicillin and cotrimoxazole; lower sensitivity to pipemidic acid with regards to norfloxacin; and high sensitivity to first--and second-generation cephalosporins. Only the knowledge of the sensitivity of pathogenic germs to antimicrobials in a specific medium can allow us to use antibiotics rationally. Knowledge can be increased by working out prospective diagnostic and treatment procedures, which could substantially improve the delivery of primary care medicines.


[The conduct stemming from the application of a program of preventive activities].

To evaluate the results of putting into practice the Programme of Preventive Measures and Health Promotion of the SEMFYC and the level of intervention into each risk factor. Descriptive study of a sample of clinical records of patients included in the program. SITE. The population seen at a Health Centre. A sample of 772 clinical records, 51.1% being women. Average age was 31.8. 389 smokers, 35 people with hypertension, 175 with hypercholesterolemia, 96 heavy drinkers and 268 suffering from overweight were found. The level of intervention recorded in the clinical histories is low by the criteria of the Programme: it swings between 27.68% for overweight and 47.6% for tobacco dependency. The Programme of Preventive Measures and Health Promotion (PAPPS in Spanish) is seen to be useful as a method of detecting health problems in the asymptomatic population. But it needs to be followed up with some minimal intervention and control of the problem, if the desired aims are to be met.


[Inequality before death: a comparative study between Navarra communities in the population segment from 25 to 74 years old].

To identify differences in mortality between communities in function of certain socio-economic factors. Firstly, between the urban and rural population of Navarra; and secondly, among different neighbourhoods in Pamplona categorised according to their socioeconomic status. Descriptive study. As the instrument of comparison, the standard mortality rates (SMR) have been used with the direct method. The relationship between mortality and socio-economic status in the neighbourhoods of Pamplona has been analysed by means of lineal regression. SITE. Institute of Public Health of Navarra. Those people recorded on the Municipal Censuses of Navarra in 1986, who were between 25 and 74 years old. 8,086 of these died during our period of study, which covered the five years between 1985 and 1989. The SMRs for all causes in men (741 x 10(6)) and women (324 x 10(6)) who live in rural communities are significantly lower (p less than 0.05) than those in urban communities (863 and 390). The specific cause of death which marks the most difference between the two types of community are tumours (p less than 0.05). In the capital (Pamplona), masculine mortality was found to increase in line with the socio-economic status of the neighbourhood lived in (p = 0.017). There is greater mortality in urban than in rural communities; and in neighbourhoods with low socio-economic status as against those with a high status. However, in this second case, the greater mortality only applies to men.


[Chronic patients confined to home and their impact on the family: a qualitative study].

To describe and assess the social and psychic overload which falls on those who care for chronically ill patients confined to their homes. Qualitative study, with semi-structured interviews. SITE: Primary care in the public sector, in an urban context. Those caring for the chronically ill, confined to their homes, and who are included in the home care programme of a General Medicine office. Semi-structured interview and analysis of the clinical history. Data were obtained concerning: 1. The general characteristics of the patient; 2. General characteristics of the carer; and 3. Social activities, family relationships and both physical and psychological health of the carers. 12 patients were studied. Two of these had no carer. In the remaining ten cases, the carer was a member of the immediate family. Only one carer was male. In 60% of cases the carer showed dysfunction in relation to the family. There were social repercussions in 70% of the cases and psychiatric morbidity in 50%. Care of the chronically ill patient confined to the home carries with it a serious social and psychological burden, which falls essentially on the wife or daughter.


[The demand for care at a health center according to the regional information system].

Our work is designed to find the level of demand for care in a health centre by studying data gathered with the system of regional information. This was a descriptive analysis of the health problems for which patients sought treatment, based on a sampling of these problems one week a month. SITE. The study, covering the whole of 1990, was carried out in an urban health centre in Valladolid. 4.1 problems per person per year were recorded. Infants under a year old constitute the category with most problems (14.3 problems per year), followed by people over 65 (13 problems per year). The biggest group of problems concerned respiratory functions and social and administrative problems. In spite of the differences in methodology, there are a large number of similarities between several studies.


Sleep classification in infants based on artificial neural networks.

The study reports on the possibility of classifying sleep stages in infants using an artificial neural network. The polygraphic data from 4 babies aged 6 weeks, 6 months and 1 year recorded over 8 hours were available for classification. From each baby 22 signals were recorded, digitized and stored on an optical disc. Subsets of these signals and additional calculated parameters were used to obtain data vectors, each of which represents an interval of 30 sec. For classification, two types of neural networks were used, a Multilayer Perceptron and a Learning Vector Quantizer. The teaching input for both networks was provided by a human expert. For the 6 sleep classes in babies aged 6 months, a 65% to 80% rate of correct classification (4 babies) was obtained for the testing data not previously seen.


[Movement correction of digital sequence angiographies of the retina].

Retinal hemodynamics can be quantified from videoangiographic image sequences by digital image processing. Intensity changes of dye dilution curves provide dynamics parameters of the local retinal blood flow. The measuring points of dye dilution curves have to be fixed on identical image contents in each image of a complete image sequence. To obtain measurements for every pixel on the retinal surface a motion-compensated image sequence is required. A new method adapted to the compensation of eye motion and movement artifacts in Scanning Laser Ophthalmoscopy in long image sequences (300-500 images) is presented in this paper. To inhibit error propagation of time sequential motion estimation, the eye movement is divided into two dynamic movements components. The method presented permits compensation for eye motion in retinal fluorescein angiographic sequences. Owing to the short calculation times, this algorithm can be used in clinical routine.


[Online control of evaluation algorithms of the image applied to identification of deglutition function].

Comprehensive software and hardware have been developed for the processing of biosignals. Such automatic signal processing, however not only has advantages, but also drawbacks. The question as to the reliability of the evaluation algorithm arises when the signal is modified, in the presence of interindividual differences, and in particular when noise is superimposed. This is of great interest for long-term recording when the original signal can no longer be inspected visually. The aim of our work was to display the signals on the screen of a monitor simultaneously with lines marking the points (start, end, extreme value, etc.) processed by the specific signal processing algorithm. The program package permits the on-line recording and monitoring of signals, the parallel processing and marking of detected events on the monitor, as well as storage of the parameters extracted. It is a very effective tool for developing, improving and monitoring of algorithms and their efficiency for signal processing.


Calorimetric studies on the influence of N-methylated headgroups on the mixing behavior of diheptadecanoyl phosphatidylcholine with 1-behenoyl-2-lauroylphosphatidylcholine.

Recent studies of five different phosphatidylcholine/phosphatidylcholine (PC/PC) systems indicate that binary mixtures of phosphatidylcholines in which one component has a normalized chain length difference (delta C/CL) in the range of 0.09-0.40 and the other a delta C/CL in the range of 0.42-0.57 exhibit the phase behavior of a eutectic system. Here, delta C is the effective chain-length difference between the two acyl chains, and CL is the effective length of the longer of the two acyl chains for the same lipid molecule in the gel state. In each mixture, gel phase immiscibility occurs over a wide compositional range due to the difference in the gel phase acyl chain packing properties of each component. Although the mixtures differ in the location of their eutectic horizontal, with respect to temperature, all have a similar eutectic point that occurs at a composition of approximately 40 mol percent of the component with the delta C/CL value in the range of 0.42-0.57. Here, we extend these studies by systematically modifying the headgroup of C(17):C(17)PC and then analyzing the mixing behavior of the modified lipid with C(22):C(12)PC using DSC. Progressive demethylation of the C(17):C(17)PC headgroup leads to an increase in gel phase immiscibility and a decrease in the amount of C(22):C(12)PC that comprises the eutectic composition. The temperature defining the location of the eutectic horizontal, however, remains virtually unchanged in all three phase diagrams. Our results suggest that the eutectic composition is influenced by changes in gel phase acyl chain packing that are dependent on headgroup-headgroup interactions. In contrast, the eutectic nature of the phase diagram and the location of its solidus line are properties of acyl chain interactions that are independent of phospholipid headgroup-headgroup interactions.


Monovalent cation binding to cubic insulin crystals.

Two localized monovalent cation binding sites have been identified in cubic insulin from 2.8 A-resolution difference electron density maps comparing crystals in which the Na+ ions have been replaced by Tl+. One cation is buried in a closed cavity between insulin dimers and is stabilized by interaction with protein carbonyl dipoles in two juxtaposed alternate positions related by the crystal dyad. The second cation binding site, which also involves ligation with carbonyl dipoles, is competitively occupied by one position of two alternate His B10 side chain conformations. The cation occupancy in both sites depends on the net charge on the protein which was varied by equilibrating crystals in the pH range 7-10. Detailed structures of the cation binding sites were inferred from the refined 2-A resolution map of the sodium-insulin crystal at pH 9. At pH 9, the localized monovalent cations account for less than one of the three to four positive counterion charges necessary to neutralize the negative charge on each protein molecule. The majority of the monovalent counterions are too mobile to show up in the electron density maps calculated using data only at resolution higher than 10 A. Monovalent cations of ionic radius less than 1.5 A are required for crystal stability. Replacing Na+ with Cs+, Mg++, Ca++ or La+++ disrupts the lattice order, but crystals at pH 9 with 0.1 M Li+, K+, NH4+, Rb+ or Tl+ diffract to at least 2.8 A resolution.


Microviscosity of human erythrocytes studied using hypophosphite two-spin order relaxation.

A new 31P NMR method is used to probe the cytoplasmic viscosity of human erythrocytes. The method is based on observing two-spin order relaxation of the 31P atom of the hypophosphite ion. This method is superior to our previous method, using the longitudinal relaxation time of the ion, because random field effects such as intermolecular dipole-dipole relaxation can be separated from intramolecular relaxation. This allows a more accurate determination of the effective reorientational correlation time from the measured intramolecular relaxation because it is now unaffected by random field effects. The new method also provides a means by which to estimate the random field effects. Both two-spin order and proton-decoupled T1 measurements were conducted on hypophosphite in water solutions at various temperatures, glycerol solutions of various viscosities, and in erythrocyte samples of various cell volumes. The results show that the effective reorientational correlation time of the hypophosphite ion varies from 7.2 to 15.2 ps in the cytoplasm of cells ranging in volume from 102 to 56 fl cells.


Ion effects on gating of the Ca(2+)-activated K+ channel correlate with occupancy of the pore.

We studied the effects of permeant ions on the gating of the large conductance Ca(2+)-activated K+ channel from rat skeletal muscle. Rb+ blockade of inward K+ current caused an increase in the open probability as though Rb+ occupancy of the pore interferes with channel closing. In support of this hypothesis, we directly measured the occupancy of the pore by the impermeant ion Cs+ and found that it strongly correlates with its effect on gating. This is consistent with the "foot-in-the-door" model of gating, which states that channels cannot close with an ion in the pore. However, because Rb+ and Cs+ not only slow the closing rate (as predicted by the model), but also speed the opening rate, our results are more consistent with a modified version of the model in which the channel can indeed close while occupied, but the occupancy destabilizes the closed state. Increasing the occupancy of the pore by the addition of other permeant (K+ and Tl+) and impermeant (tetraethylammonium) ions did not affect the open probability. To account for this disparity, we used a two-site permeation model in which only one of the sites influenced gating. Occupancy of this "gating site" interferes with channel closing and hastens opening. Ions that directly or indirectly increase the occupancy of this site will increase the open probability.


Dynamics of energy transfer and trapping in the light-harvesting antenna of Rhodopseudomonas viridis.

By low intensity picosecond absorption spectroscopy it is shown that the exciton lifetime in the light-harvesting antenna of Rhodopseudomonas (Rps.) viridis membranes with photochemically active reaction centers at room temperature is 60 +/- 10 ps. This lifetime reflects the overall trapping rate of the excitation energy by the reaction center. With photochemically inactive reaction centers, in the presence of P+, the exciton lifetime increases to 150 +/- 15 ps. Prereducing the secondary electron acceptor QA does not prevent primary charge separation, but slows it down from 60 to 90 +/- 10 ps. Picosecond kinetics measured at 77 K with inactive reaction centers indicates that the light-harvesting antenna is spectrally homogeneous. Picosecond absorption anisotropy measurements show that energy transfer between identical Bchlb molecules occurs on the subpicosecond time scale. Using these experimental results as input to a random-walk model, results in strict requirements for the antenna-RC coupling. The model analysis prescribes fast trapping (approximately 1 ps) and an approximately 0.5 escape probability from the reaction center, which requires a more tightly coupled RC and antenna, as compared with the Bchla-containing bacteria Rhodospirillum (R.) rubrum and Rhodobacter (Rb.) sphaeroides.


Significance of glomerular compartmentalization for olfactory coding.

This paper deals with the dendritic signal processing by mitral cells in the olfactory bulb and its meaning for olfactory coding. The output signals of olfactory receptor neurones are sent to the olfactory bulb where they converge onto the secondary neurones, the mitral cells. On a short time scale, the connectivity between receptor and mitral cells can be assumed to be constant, whereas on a longer time scale, when considering the ongoing de- and regeneration, it is necessary to model the synaptical weights between receptor and mitral cells as variables. In a first approach we used Hebb's rule to this end and presumed that a mitral cell can be represented by one compartment only. In this case, and with a sequence of realistically modeled receptor activity signals, the synaptical weights of all mitral cells converged to the same point though every mitral cell had initial weights different from those of any other mitral cell. This means that a mitral cell, when modeled as one compartment, does not become sensitive to any particular odor quality. A similar lack of quality tuning turned out to occur when one-compartment mitral cells were connected among each other by laterally inhibiting interneurones. We therefore took into account the glomerular fine structure of mitral cell dendrites, assuming electrotonically decoupled dendritic subbranches. This feature together with local inhibitory circuitry at the subbranches led to a fundamentally different type of synaptical convergence pattern. In this case, mitral cells developed differential sensitivities for different odors. Mitral cells have thus to be regarded as multicompartment cells, and local, non-Hebbian learning rules for their afferent synapses are necessary to achieve a reasonable map of odors upon mitral cell activities.


Spectral hole burning study of protoporphyrin IX substituted myoglobin.

Protoporphyrin IX substituted myoglobin reveals excellent hole burning properties. We investigated the frequency shift of persistent spectral holes under isotropic pressure conditions in a range from 0 to 2.4 MPa. In this range, the protein behaves like an elastic solid. The shift of the holes under pressure shows a remarkable frequency dependence from which the compressibility of the protein can be determined. The compressibility, in turn, allows for an estimation of the equilibrium volume fluctuations. Within the frame of the model used to interpret the pressure data, it is possible to determine the absorption frequency of the isolated chromophore and the associated solvent shift in the protein environment.


Structural polymorphism correlated to surface charge in filamentous bacteriophages.

Fiber diffraction studies are used to demonstrate that changes in the helical symmetry of the protein coat of filamentous bacterial viruses fd and M13 are correlated with changes in the surface charge. Comparison of the structure of M13 and fd at pH 2 and 8 indicate that surface charge affects both the helical symmetry and flexibility of the virions. The changes in helical symmetry are similar in magnitude to that observed in the Pseudomanas phage Pf1 and probably reflect an inocuous side effect of the particle flexibility required for protection of the virus particles from damage due to shear. The magnitude of the observed changes in helical symmetry appears to be limited to that which can occur without repacking of the interfaces between the alpha-helices making up the viral protein coat.


Multiple conductances in the large K+ channel from Chara corallina shown by a transient analysis method.

The large conductance K+ channel in the tonoplast of Chara corallina has subconductance states (substates). We describe a method that detects substates by monitoring the time derivative of channel current. Substates near to the full conductance tend to have long durations and high probabilities, while those of smaller amplitude occur with less probability and short duration. The substate pattern is similar in cell-attached, inside-out and outside-out patches over a range of temperatures. The pattern changes at high Ca2+ concentration (10 mol m-3) on the cytoplasmic face of inside-out patches. One substate at approximately 50% of the full conductance is characterized by a high frequency of transitions from the full conductance level. This midstate conductance is not a constant proportion of the full conductance but changes as a function of membrane potential difference (p.d.) showing strong inward rectification. We suggest that the channel is a single pore that can change conformation and/or charge profile to give different conductances. The mean durations of the full conductance level and the midstate decrease as the membrane p.d. becomes more negative. Programs for analysis of channel kinetics based on an half-amplitude detection criterion are shown to be unsuitable for analysis of the K+ channel.


Cable analysis with the whole-cell patch clamp. Theory and experiment.

A theoretical analysis was undertaken of a Rall motoneuron under voltage clamp with a finite access resistance. This model is relevant to the conditions of the whole-cell patch clamp, which to date has been used very little for cable analysis. It was shown that the soma and cable charging currents can be distinguished, and that the soma is charged with a time constant approximately equal to the access resistance times the somatic capacitance. Thus, the charging time of the soma is similar to what it would be if the cell had no process. Simple formulas were derived that can be used to calculate the electrotonic length, the membrane time constant, and the soma-dendrite resistance ratio of a cell with a cylindrical process. With the aid of these formulas, reasonable estimates of parameter values were recovered from simulated transient currents. Tests of the Rall model were proposed to determine when there is an equivalent cylinder that is consistent with observed charging behavior. The analysis was extended to a cable with an open end and to a model in which the soma and dendrite have different membrane time constants. It was shown that with voltage-clamp data estimates of electrical parameters other than rho are relatively insensitive to differences between the membrane properties of the soma and dendrite. The methods of cable analysis introduced here were illustrated by application to charging transients recorded from a hippocampal pyramidal cell and from a neurohypophysial nerve ending. The Rall model provided a good description of the pyramidal cell current transient but was inconsistent with the charging behavior observed for the nerve ending. With the recent technical advance of patch clamp recording in brain slices, the analysis presented here should help neurophysiologists investigate cable properties in a wide variety of systems.


Comparison of the lipid acyl chain dynamics between small and large unilamellar vesicles.

13C NMR spin-lattice relaxation (T1) rates and 13C-1H nuclear Overhauser effects (NOEs) were measured in an identical fashion in two lipid preparations having dramatically different curvatures. The T1 times that were obtained at four magnetic field strengths were fit along with the NOEs to simple models for lipid molecular dynamics. The results indicate that phospholipid chain ordering and dynamics are virtually identical in small and large unilamellar vesicles at the time scales sampled by these 13C-NMR studies. The order parameters and reorientational correlation times that characterize the amplitudes and rates of internal acyl chain motions were equal within experimental error for the methylene segments in the middle of the chains. The only significant differences in order parameters and correlation times between the two vesicle types were small and appeared at the ends of the acyl chains. At the carbonyl end the order was slightly higher in small vesicles than large vesicles, and at the methyl end the order was slightly lower for small vesicles. This indicates that in the more planar systems the acyl chains exhibit a slightly flatter order profile than in more highly curved membranes. The use of the same experimental approach in both small and large vesicle systems provided a more reliable and accurate assessment of the effect of curvature on molecular order than has been previously obtained.


Intermolecular protein interactions in solutions of calf lens alpha-crystallin. Results from 1/T1 nuclear magnetic relaxation dispersion profiles.

From analyses of the magnetic field dependence of 1/T1 (NMRD profiles) of water protons in solutions of calf lens alpha-crystallin at several concentrations, we find two regimes of solute behavior in both cortical and nuclear preparations. Below approximately 15% vol/vol protein concentration, the solute molecules appear as compact globular proteins of approximately 1,350 (cortical) and approximately 1,700 (nuclear) kD. At higher concentrations, the effective solute particle size increases, reversibly, as evidenced by the appearance of spectra-like 14N peaks in the NMRD profiles and a change in the field and temperature dependence of 1/T1. At these higher concentrations, the profiles are very similar to those of calf gamma II-crystallin, a crystallin that undergoes an analogous transition near approximately 15% protein (Koenig, S. H., C.F. Beaulieu, R. D. Brown III, and M. Spiller, 1990. Biophys. J. 57:461-469). By comparison with recent analyses of NMRD results for solutions of immobilized proteins as models for the transition from protein solutions to tissue (Koenig, S. H., and R. D. Brown III. 1991. Prog. NMR Spectr. 22:487-567), we argue that alpha-crystallin solute behaves as aggregates approximately greater than 50,000 kD as protein concentration is progressively increased above 15%. Finally, the concentration dependence of the NMRD profiles of alpha- and gamma II-crystallin can readily explain recent osmotic pressure data, in particular the intersection of the respective pressure curves at approximately 23% vol/vol (Vérétout, F., and A. Tardieu. 1989. Eur. Biophys. J. 17:61-68).


Modulation of the interbilayer hydration pressure by the addition of dipoles at the hydrocarbon/water interface.

The effects of the cholesterol analog 5 alpha-cholestan-3 beta-ol-6-one (6-ketocholestanol) on bilayer structure, bilayer cohesive properties, and interbilayer repulsive pressures have been studied by a combination of x-ray diffraction, pipette aspiration, and dipole potential experiments. It is found that 6-ketocholestanol, which has a similar structure to cholesterol except with a keto moiety at the 6 position of the B ring, has quite different effects than cholesterol on bilayer organization and cohesive properties. Unlike cholesterol, 6-ketocholestanol does not appreciably modify the thickness of liquid-crystalline egg phosphatidylcholine (EPC) bilayers, and causes a much smaller increase in bilayer compressibility modulus than does cholesterol. These data imply that 6-ketocholestanol has both its hydroxyl and keto moieties situated near the water-hydrocarbon interface, thus making its orientation in the bilayer different from cholesterol's. The addition of equimolar 6-ketocholestanol into EPC bilayers increases the magnitude, but not the decay length, of the exponentially decaying repulsive hydration pressure between adjacent bilayers. Incorporation of equimolar 6-ketocholestanol into EPC monolayers increases the dipole potential by approximately 300 mV. These data are consistent with our previous observation that the magnitude of the hydration pressure is proportional to the square of the dipole potential. These results mean that 6-ketocholestanol, despite its location in the bilayer hydrocarbon region, approximately 10 A from the physical edge of the bilayer, modifies the organization of interlamellar water. We argue that the incorporation of 6-ketocholestanol into EPC bilayers increases the hydration pressure, at least in part, by increasing the electric field strength in the polar head group region.


Events leading to the opening and closing of the exocytotic fusion pore have markedly different temperature dependencies. Kinetic analysis of single fusion events in patch-clamped mouse mast cells.

The earliest event in exocytosis is the formation of a fusion pore, an aqueous channel that connects the lumen of a secretory granule with the extracellular space. We can observe the formation of individual fusion pores and their subsequent dilation or closure by measuring the changes in the admittance of patch-clamped mast cells during GTP gamma S-stimulated exocytotic fusion. To investigate the molecular structure of the fusion pore, we have studied the temperature dependency of the rate constants for fusion pore formation and closure. An Arrhenius plot of the rate of fusion pore formation shows a simple linear relationship with an apparent activation energy of 23 kcal/mol. In contrast, the Arrhenius plot of the rate of closure of the fusion pore is discontinuous, with the break at approximately 13 degrees C. Above the break point, the rate of closure has a weak temperature dependence (7 kcal/mol), whereas below 13 degrees C the rate of closure is temperature independent. This type of temperature dependency is characteristic of events that depend on diffusion in a lipid phase that undergoes a fluid-solid phase transition. We propose that the formation of the fusion pore is regulated by the conformational change of a molecular structure with a high activation energy, whereas the closure of the fusion pore is regulated by lipids that become phase separated at 13 degrees C.


Determination of electric field threshold for electrofusion of erythrocyte ghosts. Comparison of pulse-first and contact-first protocols.

Rabbit erythrocyte ghosts were fused by means of electric pulses to determine the electrofusion thresholds for these membranes. Two protocols were used to investigate fusion events: contact-first, and pulse-first. Electrical capacitance discharge (CD) pulses were used to induce fusion. Plots of fusion yield vs peak field strength yielded curves that intersected the field strength axis at positive values (pseudothresholds) which depended on the protocol and decay half time of the pulses. It was found that plots of pseudothreshold vs reciprocal half time were linear for each protocol; when extrapolated to reciprocal half time = 0 (i.e., t----infinity), these lines intersected the ordinate at values of the field strength considered to be the true electrofusion thresholds. In this fashion, the contact-first protocol gave an electrofusion threshold of 46.5 +/- 11.5 V/mm for hemoglobin-free ghosts (white ghosts) and 40.9 +/- 8.8 V/mm for ghosts with fractional hemoglobin (pink ghosts), while the threshold for the pulse-first protocol applied to pink ghosts was determined to be 93.4 +/- 11.0 V/mm. Although the thresholds depended on the electrofusion protocol, plots of critical field strength vs reciprocal time had the same slopes, i.e., approximately 24 Vs/mm. The results suggest that the fusogenic state induced by an electric pulse in either the contact-first protocol or the pulse-first protocol (long-lived fusogenic state) may in fact share a common mechanism, if the two states are not actually identical.


Flexibility in crystalline insulins.

Comparisons of atomic models for chemically identical protein molecules solved in differing crystal environments provide information on flexibility in the protein structure. The structures of five T4 lysozyme proteins in differing crystal environments showed large relative displacements of the two domains with conserved backbone conformations that are connected by a flexible hinge (H. R. Faber and B. W. Matthews. 1990. Nature (Lond.). 348:263-266). In contrast, my comparison of the positions of all the atoms in two crystal forms of insulin shows that the structural changes caused by the differing crystal contacts are contained within nearby amino acids and are not propagated through the core of the insulin molecule. Groups of atoms that are most significantly displaced are not shifted in large rigid units but are repacked into new and distinct conformations. The transmission of displacements through the single domain insulin molecule is, like the movements due to thermal vibrations (D. L. D. Caspar, J. Clarage, D. M. Salunke, M. S. Clarage. 1988. Nature (Lond.). 332:659-662), characterized by short-range interactions between small atomic groups.


A residue substitution near the beta-ionone ring of the retinal affects the M substates of bacteriorhodopsin.

The switch in the bacteriorhodopsin photocycle, which reorients access of the retinal Schiff base from the extracellular to the cytoplasmic side, was suggested to be an M1----M2 reaction (Váró and Lanyi. 1991. Biochemistry. 30:5008-5015, 5016-5022). Thus, in this light-driven proton pump it is the interconversion of proposed M substates that gives direction to the transport. We find that in monomeric, although not purple membrane-lattice immobilized, D115N bacteriorhodopsin, the absorption maximum of M changes during the photocycle: in the time domain between its rise and decay it shifts 15 nm to the blue relative to the spectrum at earlier times. This large shift strongly supports the existence of two M substates. Since D115 is located near the beta-ionone ring of the retinal, the result raises questions about the possible involvement of the retinal chain or protein residues as far away as 10 A from the Schiff base in the mechanism of the switching reaction.


Supercritical fluid extraction in the determination of tobacco-specific N-nitrosamines in smokeless tobacco.

A new approach to the analysis of the carcinogenic, tobacco-specific N-nitrosamines (TSNA) in moist snuff tobacco is based on the extraction of tobacco with methanol-modified supercritical carbon dioxide. Extracted TSNA are trapped across a glass cartridge filled with Tenax GR, from which they are subsequently released by thermal desorption and analyzed by capillary gas chromatography with a thermal energy analyzer. The analytical recoveries for the major TSNA range from 83 to 98%; the detection limits are below 2 ng/g. The methodology is fast, reproducible, highly selective, and sensitive. The supercritical fluid extraction (SFE) releases up to 7 times more of the highly carcinogenic 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) from tobacco than has been determined after conventional solvent extraction. Studies have confirmed that this is not an artifact. In contrast, the cyclic N-nitrosamines, N'-nitrosonornicotine, N'-nitrosoanabasine, and N'-nitrosoanatabine, showed no significant quantitative differences whether determined by the SFE method or the conventional solvent extraction method.


The oxidation of 4-aminobiphenyl by horseradish peroxidase.

The oxidation of the carcinogen 4-aminobiphenyl (4-ABP) catalyzed by the model peroxidase enzyme horseradish peroxidase (HRP) was investigated. 4-ABP served as a reducing cosubstrate for HRP during the enzyme-catalyzed reduction of the synthetic hydroperoxide, 5-phenyl-4-penten-1-yl hydroperoxide, to its corresponding alcohol. Spectral analysis during the incubation of HRP, 4-ABP, and H2O2 showed an increase in absorbance at 230 and 325 nm and decrease at 270 nm, suggesting metabolite formation. Oxygen consumption was not detected in incubations of HRP, 4-ABP, and H2O2. However, oxygen uptake was observed after the addition of glutathione, which indicated that a free radical metabolite of 4-ABP was formed by the peroxidase. The 4-ABP free radical reacted with glutathione forming a glutathionyl radical which, in turn, reacted with and consumed oxygen. HPLC analysis of organic extracts of incubations with HRP, [3H]-4-ABP, and H2O2 showed the formation of one major peak identified by mass spectroscopy as 4,4'-azobis(biphenyl). The addition of glutathione to the incubations decreased the formation of 4-ABP metabolites, suggesting a reduction of the 4-ABP free radical and/or the formation of glutathione conjugates. Subsequent HPLC analysis of incubations including [35S]glutathione indicated formation of several unidentified 4-ABP-glutathione conjugates as well as recovery of parent compound. These studies suggest that HRP metabolizes 4-ABP by a one-electron oxidation mechanism, resulting in formation of a free radical. This radical can either react with a second radical to form azobis(biphenyl), be reduced by glutathione back to parent, or react with glutathione to form glutathione conjugates.


Correlation studies of anodic peak potentials and ionization potentials for polycyclic aromatic hydrocarbons.

One-electron oxidation represents one of the major metabolic pathways of bioactivation of polycyclic aromatic hydrocarbons (PAH) to ultimate carcinogens capable of binding to cellular macromolecules, thereby initiating the cancer process. Since the ionization potential (IP) is related to the ease of removal of a pi electron from an aromatic molecule, a low IP is a necessary condition for the PAH to undergo one-electron oxidation. The principal aim of this study was to provide a general and simple technique suitable for obtaining IP of PAH with satisfactory accuracy. Anodic peak potentials (Eap) of 90 PAH were measured by cyclic voltammetry under irreversible oxidation conditions and correlated with the corresponding IP. This allowed determination of a least-squares regression line. From the corresponding equation, IP = 1.70Eap + 5.29, IP can be calculated with a narrow margin of error after a simple electrochemical measure. It was also found that PAH substituted with a methyl group on a position of appreciable electron density are best represented by a different line, corresponding to the equation IP = 1.65Eap + 5.27. The calculated IP were also compared to other tabulated values, determined by different experimental techniques, and our set of IP values proved to yield the most satisfactory correlation. For some PAH, further studies under reversible voltammetric conditions allowed determination of two additional parameters: formal oxidation potentials (Eo) and the number of electrons (n) involved in the redox process. IP is an important parameter in predicting the metabolic activation of carcinogenic PAH.


Antioxidant activity of the pyridoindole stobadine. Pulse radiolytic characterization of one-electron-oxidized stobadine and quenching of singlet molecular oxygen.

Antioxidant properties of stobadine, a pyridoindole derivative described to exhibit cardioprotective properties, were characterized. The radical scavenging potential of stobadine was evaluated using pulse radiolysis with optical detection, by which it is shown that one-electron oxidation of stobadine with radicals such as C6H5O., CCl3O2., Br2.-, and HO. (reaction rate constants approximately 5 x 10(8)-10(10) M-1 s-1) leads to the radical cation (absorbance maxima at 280 and 445 nm) which deprotonates from the indolic nitrogen (pKa = 5.0) to give a nitrogen-centered radical (absorbance maxima at 275, 335, and 410 nm), probably bearing a positive charge at the pyrido nitrogen. The radical of stobadine reacts with Trolox (i.e., 6-hydroxy-2,5,7,8-tetramethyl-chromane-2-carboxylic acid) with a rate constant of 1.2 x 10(7) M-1 s-1 at pH 7.0 by one-electron oxidation to yield the phenoxyl-type radical of Trolox. This reaction is reversible (k = 2 x 10(5) M-1 s-1). The redox potential of stobadine at pH 7 is 0.58 V/NHE. Stobadine is also a quencher of singlet molecular oxygen (1O2) with an overall quenching rate constant of 1.3 x 10(8) M-1 s-1, determined with the endoperoxide of 3,3'-(1,4-naphthylene)dipropionate (NDPO2) as 1O2 source and by monitoring 1O2 photoemission with a germanium diode.


Bioactivation mechanism of S-(3-oxopropyl)-N-acetyl-L-cysteine, the mercapturic acid of acrolein.

S-(3-Oxopropyl)glutathione, the glutathione conjugate of acrolein, has been reported to be nephrotoxic. The objective of the present studies was to investigate the bioactivation mechanism of the analogues S-(3-oxopropyl)-N-acetyl-L-cysteine (1) and S-(3-oxopropyl)-N-acetyl-L-cysteine S-oxide (2) and to test the hypothesis that the cytotoxicity of 1 is associated with its latent potential to release acrolein in kidney cells. Mechanistic considerations indicated that sulfoxidation of sulfide 1 to form S-oxide 2 and a subsequent general-base-catalyzed beta-elimination reaction would release the cytotoxin acrolein. Hence the release of acrolein from 1 and 2 was studied in chemical systems, and their cytotoxicity was investigated in cultured LLC-PK1 cells and in isolated rat renal proximal tubular cells. Acrolein formation from S-oxide 2, but not from sulfide 1, was observed under basic conditions and with phosphate as the base. Kinetic analysis indicated that a general-base-catalyzed reaction was involved. Both S-conjugates 1 and 2 were cytotoxic in LLC-PK1 cells and in isolated rat renal proximal tubular cells, and the cytotoxicity of sulfide 1, but not of S-oxide 2, in isolated renal proximal tubular cells was reduced in presence of methimazole, an inhibitor of the flavin-containing monooxygenase. These findings indicate that the cytotoxicity of S-conjugate 1 is associated with a novel bioactivation mechanism that involves sulfoxidation followed by a general-base-catalyzed elimination of acrolein from S-oxide 2.