Effects of diphenyl ether herbicides on porphyrin accumulation by cultured hepatocytes. Several diphenyl ether herbicides, such as acifluorfen methyl, have been previously shown to cause large accumulations of the heme and chlorophyll precursor, protoporphyrin, in plants. Light-induced herbicidal damage is mediated by the photoactive porphyrin. Here we investigate whether diphenyl ether herbicides can affect porphyrin synthesis in rat and chick hepatocytes. In rat hepatocyte cultures, protoporphyrin, as well as coproporphyrin, accumulated after treatment with acifluorfen or acifluorfen methyl. Combination of acifluorfen methyl with an esterase inhibitor to prevent the conversion of acifluorfen methyl to acifluorfen resulted in a greater accumulation of porphyrins than caused by acifluorfen methyl or acifluorfen alone. In vitro enzyme studies of hepatic mitochondria isolated from rat and chick embryos demonstrated that protoporphyrinogen oxidase, the penultimate enzyme of heme biosynthesis, was inhibited by low concentrations of acifluorfen, nitrofen, or acifluorfen methyl with the latter being the most potent inhibitor. These findings indicate that diphenyl ether treatment can cause protoporphyrin accumulation in rat hepatocyte cultures and suggest that this accumulation was associated with the inhibition of protoporphyrinogen oxidase. In cultured chick embryo hepatocytes, treatment with acifluorfen methyl plus an esterase inhibitor caused massive accumulation of uroporphyrin rather than protoporphyrin or coproporphyrin. Specific isozymes of cytochrome P450 were also induced in chick embryo hepatocytes. These effects were not observed in the absence of an esterase inhibitor. These results suggest that diphenyl ether herbicides can cause uroporphyrin accumulation similar to that induced by other cytochrome P450-inducing chemicals such as polyhalogenated aromatic hydrocarbons in the chick hepatocyte system.


Species differences in membrane susceptibility to lipid peroxidation. The susceptibility of liver microsomes to lipid peroxidation was evaluated in seven species: rat, rabbit, trout, mouse, pig, cow, and horse. Lipid peroxidation was measured as thiobarbituric acid reactive substances formed in the presence of either FeCl3-ADP/ascorbate or FeCl2/H2O2 initiating systems. For rat, rabbit, and trout microsomes, the order of susceptibility to peroxidation was rat greater than rabbit much greater than trout. The lack of peroxidation in trout microsomes could be explained by high microsomal vitamin E levels. Membrane fatty acid levels differed between species. Docosahexaenoic acid predominated in the trout, arachidonic acid in the rat, and linoleic acid in the rabbit. The contribution of individual fatty acids to lipid peroxidation reflected the degree of unsaturation with docosahexaenoic greater than arachidonic much much greater than linoleic. For all species except trout, the predicted susceptibility to peroxidation, based on the response of individual fatty acids, agreed well with directly measured microsomal peroxidation. With the exception of the trout, vitamin E content ranged from 0.083-0.311 nmol/mg microsomal protein between species, and low levels did not influence susceptibility to peroxidation. Trout microsomes peroxidized only after vitamin E depletion by prolonged incubation. The data indicate that below a vitamin E threshold, species differences in membrane susceptibility to peroxidation can be reasonably predicted based only on content of individual peroxidizable fatty acids.


Changes in population density and distribution of Ixodes dammini (Acari: Ixodidae) in Wisconsin during the 1980s. Changes in the density and distribution of Ixodes dammini, Spielman Clifford, Piesman & Corwin were assessed in Wisconsin by examining hunter-killed deer for ticks in 1981 and 1989. Deer examination sites were distributed widely across the state and included 23 sites in 1981 and 15 sites in 1989; 10 sites were visited both years. Between 1981 and 1989, I. dammini became more abundant throughout its range, and I. dammini range expanded into the southwestern portion of Wisconsin. I. dammini was not found in the eastern one-third of the state. When compared with 1981, the 1989 survey revealed significant increases in the proportion of infested deer in the southwest (Arena), higher levels of infestation of individual deer (number of ticks per individual deer) in the central west (Bangor-W. Salem), and significantly less disparity between the proportions of infested male deer and infested female deer in the north (Spooner) compared with sites farther south. These results are consistent with a pattern of I. dammini range expansion from north to south, followed by an increase in population density in the colonized areas. Dermacentor albipictus Packard was present throughout the range of I. dammini and at sites in the northeastern quadrant of Wisconsin where I. dammini was not found. The range of D. albipictus did not change between the survey years, but its population density increased significantly at sites in the north. There is no evidence for interaction between the two tick species that might affect tick distribution or population density, nor can the greater number of I. dammini found in 1989 be attributed to increased tick activity because of warmer weather; temperatures were cooler in 1989 than 1981.


Phlebotomine sandflies in Venezuela: review of the verrucarum species group (in part) of Lutzomyia (Diptera: Psychodidae) with description of a new species from Lara. The series townsendi and verrucarum of the verrucarum species group of the phlebotomine genus Lutzomyia França are reviewed. Lutzomyia nadiae, new species, from the mountains of Yacambú, Lara State, is described. Distribution maps, illustrated keys, notes on medical importance, taxonomy, and ecology are presented for species in these series known from Venezuela.


Survival and vertical distribution of larvae of Culicoides variipennis (Diptera: Ceratopogonidae) in drying mud habitats. The ability of third and fourth instars of Culicoides variipennis (Coquillett) to survive in drying sandy loam soil was tested under simulated field conditions. Two hundred larvae were added to each of a number of soil-filled, plastic tubes, which were buried in the field and retrieved after 2, 5, and 7 d. Of 306 pupae or pupal exuviae recovered, 98.1% were in the top 2 cm of mud. Estimated larval mortality on day two ranged from 25.6 to 87.1% among three trials, and 92.3% of live larvae were in the top 2 cm. Estimated larval mortality on day 5 ranged from 81.4 to 97.2%, and 75.5% of live larvae were in the top 2 cm. On day 7 mortality was 95.2-100%, and 63% of surviving larvae were in the top 2 cm. Some larvae dispersed as deep as 7-10 cm (the maximum depth in the tests). Larval tolerance of unfavorable drying conditions may allow relic populations to persist in some situations, but probably this is of little concern in control of this species through water management in most settings.


Laboratory studies on the life cycle of Amblyomma marmoreum (Acari: Ixodidae) on two different hosts. A comparative study was made of the life cycle of the tortoise tick, Amblyomma marmoreum Koch, on tortoises and guinea pigs under laboratory conditions. At 25 degrees C and 85% RH with natural day length, duration of off-host stages (preoviposition, oviposition, incubation, and premolt) was similar for ticks fed on both hosts. Delay in preoviposition (up to 90 d) was observed in some gravid females. Larvae, nymphs, and adults had longer feeding periods on tortoises than on guinea pigs. Adult females fed on tortoises had greater engorgement wieght and ovipositional capacity than ticks fed on guinea pigs. It is suggested that the shortened feeding period of immature stages on mammalian hosts together with the occurrence of morphogenic diapause may be more important than previously recognized in determining whether the life cycle of A. marmoreum is completed in 1 or 2 yr under natural conditions.


Immunization of rabbits against nymphs of Amblyomma hebraeum and A. marmoreum (Acari: Ixodidae). Himalayan rabbits immunized with homogenates prepared from nymphs of Amblyomma hebraeum Koch and A. marmoreum Koch ticks developed humoral and probably also cell-mediated immunity to their respective homogenates. Beta and gamma globulin levels and numbers of eosinophils and neutrophils increased significantly in inoculated rabbits. The recipient animals developed resistance to homospecific nymphal infestations. Cross resistance between the two species was not evaluated. Nymphs of both species that fed on inoculated rabbits demonstrated slightly shorter feeding periods, and their mean weights were significantly lower than nymphs that fed on Quil 'A' adjuvant-inoculated rabbits or on naive rabbits. Significantly higher proportions of nymphs from immunized animals failed to moult when compared with nymphs that fed on the two control groups. These parameters indicate that the inoculated rabbits had acquired protective immunity against nymphs of both ticks.


Parasitic arthropods of sympatric meadow voles and white-footed mice at Fort Detrick, Maryland. Twelve species of parasitic arthropods (one sucking louse, two fleas, one tick, and eight mites) were recovered from 51 meadow voles, Microtus pennsylvanicus (Ord); whereas nine species (one sucking louse, one bot, three fleas, one tick, and three mites) were collected from 48 white-footed mice, Peromyscus leucopus (Rafinesque), live-trapped on the grounds of Fort Detrick, Frederick County, MD., during 1990 and 1991. The most commonly collected arthropods from M. pennsylvanicus were the fur mite, Listrophorus mexicanus Fain (approximately 2,720 specimens); the tropical rat mite, Ornithonyssus bacoti (Hirst) (987); the laelapid mites, Laelaps kochi Oudemans (733) and Androlaelaps fahrenholzi (Berlese (322); the sucking louse, Hoplopleura acanthopus (Burmeister) (121); the tick, Dermacentor variabilis (Say) (47); and the chigger mite, Neotrombicula whartoni (Ewing) (45). Arthropod densities were lower on P. leucopus, from which the most frequently recorded species were the sucking louse, Hoplopleura hesperomydis (Osborn) (98 specimens); the fleas, Epitedia wenmanni (Rothschild) (85) and Orchopeas leucopus (Baker) (61); and the mite, A. fahrenholzi (83). Although six species of arthropods parasitized both species of rodents, only two of these, A. fahrenholzi and D. variabilis, were relatively common on both hosts. Therefore, although the habitats of both host species partially overlap, their associated parasitic arthropods remain principally host specific. The potential significance of these findings with respect to vector-borne disease transmission is discussed.


Replication and tissue tropisms of Crimean-Congo hemorrhagic fever virus in experimentally infected adult Hyalomma truncatum (Acari: Ixodidae). Adult Hyalomma truncatum Koch ticks were inoculated intracoelomically with Crimean-Congo hemorrhagic fever (CCHF) virus to examine tissue tropisms of this virus in ticks. Virus was recovered from all 185 ticks examined between 2 and 42 d after inoculation with CCHF virus. Titers or virus recovered from unfed male and female ticks were essentially the same (means, 10(2.4) and 10(2.5) plaque-forming units [PFU] per tick, respectively). Infection rates and titers recovered per gland for both salivary glands and reproductive tissues (ovaries and testes) were positively associated with blood feeding; average titers were 10-fold greater in organs from fed compared with those from unfed individuals. In contrast, neither the tick's sex nor feeding status (unfed or engorged) affected the titer of virus recovered from hemolymph (mean, 10(1.6) PFU/microliters). Although virus was recovered from Malpighian tubules, midgut, muscle, and nervous tissues from nearly all of the ticks tested, viral titers were consistently low. The increase in viral titer associated with blood feeding by ticks appeared to be due primarily to proliferation of tissue (e.g., salivary gland and reproductive tissues), rather than to increased replication in tissue already present.


Immune response of lizards and rodents to larval Ixodes scapularis (Acari: Ixodidae). The house mouse (laboratory strain), Mus musculus (L.), the cotton mouse, Peromyscus gossypinus (LeConte), the broad-headed skink, Eumeces laticeps (Schneider), and the guinea pig, Cavia porcellus (L.), were successively infested five times with larvae of the blacklegged tick, Ixodes scapularis Say. Tick feeding success, engorgement weight, and subsequent molting success were measured after each infestation. A greater percentage of ticks (P less than 0.05) fed on M. musculus and E. laticeps than on P. gossypinus or C. porcellus. P. gossypinus expressed a transitory partial resistance, measured in percentage of ticks feeding, during the third infestation but showed increased tolerance during the fourth and fifth infestations. Ticks fed on E. laticeps were heavier than those fed on any other host (P less than 0.05). Those fed on M. musculus were heavier than those fed on P. gossypinus, but the difference was not statistically significant. On C. porcellus, only 1.6% of larvae from the third infestation and none thereafter engorged; weights of larvae from first and second infestations were higher (P less than 0.05) than those fed on M. musculus and P. gossypinus and lower (P less than 0.05) than those fed on E. laticeps. A greater percentage of larvae from E. latticeps and M. musculus (P less than 0.05) molted to nymphs compared with those from P. gossypinus and C. porcellus. Molting success was the same for ticks fed on P. gossypinus and on C. porcellus during the first and second infestations. M. musculus, P. gossypinus, and E. laticeps expressed no resistance (measured as percentage feeding, engorgement weight, and molting) to feeding by I. scapularis larvae after five infestations. Host serum was tested using an ELISA for detection of antibodies against I. scapularis salivary gland antigens before and after each infestation. Antibodies were detected after the second infestation and thereafter in C. porcellus, the only species to show antibodies or to express and maintain an acquired resistance to tick feeding throughout five infestations.


Differences in male mating response and female flight sounds in Aedes aegypti and Ae. albopictus (Diptera: Culicidae). Aedes aegypti (L.) and Ae. albopictus (Skuse) showed similar rates and timing of insemination in the laboratory. Laboratory attempts at interspecific mating were unsuccessful. Because Ae. aegypti males are known to locate females by flight sounds, male response to sound was compared in the two species. Ae. aegypti males responded to female flight sounds with stereotypical orientation and mating behavior, whereas Ae. albopictus males seldom responded. Recorded flight sounds of females were sampled via computer digitization and compared. Ae. aegypti females produced louder sounds with more harmonics than Ae. albopictus. Males were tested for their ability to discriminate between the sounds of the two species. Ae. albopictus males did not respond to recordings of either Ae. albopictus or Ae. aegypti females. Ae. aegypti males responded preferentially to the recorded sounds of Ae. aegypti females. Thus, males of the two species use different mechanisms in locating mates. Ae. aegypti males rely more on sound than do Ae. albopictus males.


Experimental transmission of Venezuelan equine encephalomyelitis virus by a strain of Aedes albopictus (Diptera: Culicidae) from New Orleans, Louisiana. Experimental studies were undertaken to ascertain the vector competence of a strain of Aedes albopictus (Skuse) collected in New Orleans, LA, (Gentilly strain) for an epizootic (Trinidad donkey) strain of Venezuelan equine encephalomyelitis (VEE) virus. This strain of Ae. albopictus was significantly more susceptible to infection with VEE virus than were any of the four strains tested previously, including two from North America and two from South America. Likewise, dissemination (148 of 180) (82%) and transmission (40 of 88) (45%) rates were significantly higher in the Gentilly strain than in any of the strains previously tested. Analysis of the results of the present study along with those of a previous study with a second alphavirus, chikungunya (CHIK) virus, indicated that, although all three strains of Ae. albopictus tested were more susceptible to VEE virus than to CHIK virus, susceptibility to infection and dissemination with one alphavirus appeared to be directly related to susceptibility to infection and dissemination with the other virus and may indicate shared receptor sites for these two alphaviruses in Ae. albopictus.


Attempted mechanical transfer of Ehrlichia risticii by tabanids (Diptera: Tabanidae). The ability of tabanid mouthparts to retain and to transfer mechanically Ehrlichia risticii Holland, Weiss, Burgdorfer, Cole & Kakoma was evaluated by feeding flies on infected and noninfected mice and on capillary tubes containing infected cells and cell-free medium. Flies representing two genera and 29 species were collected at equine boarding stables, farms, and along riding trails in Wake, Johnston, and Duplin counties in North Carolina for the feeding trials. Two species, Tabanus fulvulus Wiedemann and T. pallidescens Philip, fed on mice but failed to transfer the pathogen from infected to susceptible mice. Chrysops vittatus Wiedemann, Tabanus americanus Forster, and T. sulcifrons Macquart transferred E. risticii-infected cells from capillary tubes containing infected cells in medium to tubes containing medium. These studies document that E. risticii-infected cells can be retained on mouthparts and potentially transferred by tabanids.


Incompetence of roe deer as reservoirs of the Lyme borreliosis spirochete. To determine whether the roe deer, Capreolus capreolus L. may serve as a reservoir host for the Lyme disease spirochete, Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner, evidence of spirochetal infection was sought in nymphal Ixodes ricinus (L.) that had engorged as larvae on roe deer. Sixteen roe deer were shot in Lyme disease enzootic areas of south-central Sweden during August-November 1990 and August 1991. An average of 276 (range, 84-658) larvae of I. ricinus was collected from each of 12 deer shot in August. Of those ticks that had fed on deer and then developed to the nymphal stage, the gut contents of 238 were examined by phase-contrast microscopy. All these ticks were negative for spirochetes, whereas 4.2% contained Trypanosoma cf. cervi Kingston & Morton and 15.1% contained the nematode Dipetalonema rugosicauda Meszaros & Sugar. A total of 396 nymphal ticks was collected by blanket-dragging during May-June 1991 and examined for spirochetes; 9.1% of these host-seeking nymphs were infected with spirochetes. Although the roe deer serves as a principal blood source for all stages of I. ricinus, it does not appear to serve as a major reservoir of B. burgdorferi.


Modulation of host-immune responses by ticks (Acari: Ixodidae): effect of salivary gland extracts on host macrophages and lymphocyte cytokine production. Ixodid tick infestation induces host acquired resistance, which involves immunoglobulin cell-mediated and complement-dependent effector pathways. Ticks have developed countermeasures to modulate host antiarthropod responses. Ixodid-mediated host immunomodulation results in vitro in reduced responsiveness to T-lymphocyte mitogens for cells obtained from infested hosts and impaired antibody responses to a thymic dependent antigen. Salivary gland extracts from days 0-9 of engorgement from unmated, female Dermacentor andersoni Stiles suppressed lymphocyte proliferative responses (LPS) to the T-cell mitogen Con A up to 68.4%, whereas responsiveness to E. coli LPS was enhanced. Cytokines assessed in this study included interleukin-1, IL-1, and tumor necrosis factor (TNF) alpha produced by macrophages, and interleukin-2, IL-2, and gamma interferon (IFN-G) secreted by T-lymphocytes. Salivary gland extracts prepared from tissues obtained on days 0-5 of engorgement suppressed IL-1 elaboration from 89.8% on day 0 through 37.5% on day 6. Levels of TNF were reduced from 40.7 to 94.6% throughout the course of the study. Production of IL-2 was suppressed by 14.1-31.9%, and IFN-G was reduced by 8.7-57.0%. Reduced IL-1 levels during the early phases of feeding indicated reduced host ability to activate T-lymphocytes and provide costimulatory, differentiation, and development signals for B-cells. Both IL-1 and TNF are endogenous pyrogens and activate polymorphonuclear leukocytes. Activities of TNF and IFN-G include antiviral properties and induction of expression of class I and II major histocompatibility complex molecules, which are critical components in the recognition of antigen by T-lymphocytes. The autocrine role of IL-2 in proliferation of T-lymphocytes is central to the development of immune reactivity involving T-cell regulation or effector functions or both. Reductions in cytokine levels would suppress immune responses directed toward immunogens introduced into the host during the course of tick feeding. These results indicates that immunomodulation of the host during tick feeding facilitates engorgement and pathogen transmission.


Comparative infections of epizootic and enzootic strains of Venezuelan equine encephalomyelitis virus in Amblyomma cajennense (Acari: Ixodidae). To compare the potential for an enzootic or an epizootic strain of Venezuelan equine encephalomyelitis (VEE) virus to infect Amblyomma cajennense (F.), larval ticks were fed on guinea pigs (strain 13) inoculated with an enzootic viral strain of variant I-E (68U201) or on guinea pigs inoculated with an epizootic strain of variant I-A (Trinidad donkey). Peak viremias were 10(5.2) plaque-forming units (PFU)/ml and 10(7.3) PFU/ml in guinea pigs infected with enzootic and epizootic viral strains, respectively. Ticks feeding on enzootic- and epizootic-infected hosts had viral titers of 10(2.5) and 10(3.9) PFU per tick, respectively, at drop-off. Although epizootic virus was recovered from 98% (127 of 130) of larval ticks up to 16 d after drop-off, enzootic virus was recovered from 95% (19 of 20) at drop-off (mean titer, 10(2.5) PFU per tick), with recovery rates declining rapidly to 2 of 10 (mean titer, 10(1.4) PFU per tick) by 16 d after drop-off. Transstadially transmitted epizootic virus was found in 0.4% (12 of 2,950) of unfed nymphs (mean titer, 10(2.8) PFU per tick) 63 d after drop-off, 1% (5 of 521) fed nymphs 69 d after drop-off, and 1% (4 of 400) of unfed adults (mean titer, 10(3.6) PFU per tick) 106 d after drop-off. No enzootic virus was recovered from 4,600 unfed nymphs tested 63 d after drop-off.


Cotton rats and other small mammals as hosts for immature Dermacentor variabilis (Acari: Ixodidae) in central Oklahoma. Eight species of small mammals were evaluated as potential hosts for American dog ticks, Dermacentor variabilis (Say), in an upland, tallgrass prairie study site in central Oklahoma. Only hispid cotton rats, Sigmodon hispidus, and deer mice, Peromyscus maniculatus, were found to be important hosts for immature D. variabilis. Although D. varibilis larvae and nymphs frequently infested both cotton rats and deer mice, cotton rats were the most important host species for both immature stages in the study area. Cotton rats constituted 63.2% of the total 530 small mammals captured and were hosts to 85.2% of all larvae and 88.7% of all nymphs. Deer mice accounted for 19.8% of all small mammals captured and were hosts for 14.5% of the larvae and 10.8% of the nymphs recovered. The remaining small mammal species were hosts for less than 1% of the immature ticks collected. Larval infestations peaked during summer, whereas summer and spring peaks were noted for the nymphal infestations. The relative importance of cotton rats and deer mice as hosts for immature ticks could be largely, but not completely, explained by cotton rats being more than three times as abundant as deer mice. Attachment site data indicated that differences in grooming behavior also might be partially responsible for the larger infestations observed on cotton rats. Other possible ecological and behavioral explanations of the heavy infestations observed on cotton rats are discussed.


Patterns of sugar feeding in diapausing and nondiapausing Culex pipiens (Diptera: Culicidae) females. In the laboratory, diapausing Culex pipiens L. females fed on a continuously available sugar source more frequently and longer after adult emergence than did non-diapausing females. They also showed an extended nocturnal pattern of sugar feeding compared with that of non-diapausing females. Differences between diapausing and non-diapausing females with respect to sugar feeding and host-seeking behavior also were related to responses to volatiles from fruit and vertebrate hosts. In this Colorado strain of Cx. pipiens, increased sugar feeding by diapausing females during the first few weeks of adult life may be an adaptation that enhances overwintering survival.


Transmission of western equine encephalomyelitis virus by Argentine Aedes albifasciatus (Diptera: Culicidae). Aedes albifasciatus (Macquart) has been considered a potential vector of western equine encephalitis (WEE) virus in Argentina because it has been found naturally infected, it is susceptible to infection per os, and its distribution and feeding habits are compatible with those of an epizootic and epidemic vector. Ae. albifasciatus females collected in the vicinity of Cordoba, Argentina, were highly susceptible to WEE virus perorally (ID50 less than 0.5 Vero cell plaque-forming units) when fed on viremic chicks. Virus transmission trials were done 9 to 16 d after infection by feeding potentially infected mosquitoes individually on chicks. Among 31 mosquitoes that survived the incubation period, six refed on susceptible chicks. Virus transmission by bite was demonstrated by five of six (83%) mosquitoes. Therefore, the final piece of evidence incriminating Ae. albifasciatus as a natural vector of WEE virus has been obtained. This is the first mosquito species to be incriminated as a vector of WEE virus in South America.


Development and evaluation of an enzyme-linked immunosorbent assay for Plasmodium vivax-VK247 sporozoites. An enzyme-linked immunosorbent assay (ELISA) for the Plasmodium vivax-VK247 (variant) circumsporozoite (CS) protein was developed and evaluated using sporozoites produced by feeding mosquitoes on Thai patients with parasitologically confirmed P. vivax infections. The ELISA had a detection threshold of fewer than 50 sporozoites. Using this assay in conjunction with an ELISA for the VK210 polymorph, nearly 16% of the 235 P. vivax cases produced sporozoites positive only for the variant; 69% produced sporozoites positive only in the VK210 assay; and 15% were positive in both assays, indicating mixed infections. Twelve cases (5%) produced sporozoites negative in one assay and with unexpectedly low activity in the other ELISA, indicating the possibility of other CS protein polymorphs.


Bite-count evaluation of the repellency of N,N-diethyl-3-methylbenzamide to larval Eutrombicula alfreddugesi (Acari: Trombiculidae). Larvae of the pest chigger mite Eutrombicula alfreddugesi Oudemans, 1910, exhibited a low repellent threshold for N,N-diethyl-3-methylbenzamide (deet) in a field setting. Use of a deet-based repellent significantly reduced chigger mite infestation. Efficacy of aerosol formulations was significantly diminished with 9% (AI) deet. E. alfreddugesi utilized both direct and indirect paths to infest the human body. Direct infestation led to the highest body region bite counts. Distribution of E. alfreddugesi bites over 15 regions of the human body fell into three zones of decreasing parasitism: the ankle/calf region (accessed through direct infestation); the groin, chest, back, armpits, and feet (accessed through indirect infestation); and the thighs, arms, buttocks, head, and neck, which were infrequently attacked or were unavailable to E. alfreddugesi.


Kinetic development and decline of antiscrewworm (Diptera: Calliphoridae) antibodies in serum of infested sheep. Sheep infested with screwworms, Cochliomyia hominivorax (Coquerel), produced specific serum antibodies detectable by ELISA. Significant antibody levels were found beginning at 1 wk after infestation and persisting for 2 mo, with peak levels at 3 wk after infestation. Mean response values and corresponding larval survivorship were similar over a range of 25 to 200 larvae per individual sheep. Anomalous seropositive responses in some noninfested sheep suggested the possibility of cross-reactivity between antigens of screwworm and those of related myiasigenic blowflies.


African swine fever virus infection in the Iberian soft tick, Ornithodoros (Pavlovskyella) marocanus (Acari: Argasidae). One thousand six hundred Ornithodoros (Pavlovskyella) marocanus Velu larvae were fed on a pig infected with African swine fever virus (titer: 10(7.4) HAd50/ml), and 1,600 larvae were fed on an uninfected pig. Ticks in each group were compared for mortality rates, mean time to death for ticks that died, mean time from feeding to either molting or eclosion, percentage of ticks that eclosed or molted, and the number of blood meals per nymph or instar. Cumulative virus-induced mortality for all immature stages (larvae to adult) of O. marocanus that had been fed as larvae on a pig infected with African swine fever was ca. 73% over a 390-d period. In contrast, less than 9% mortality was observed among ticks fed on uninfected pigs. Mean time to death for infected ticks was 15-87 d versus 10-17 d for uninfected ticks. Differences in the premolt period (number of days from blood meal to molt) between infected and control ticks were not observed. Mean premolt periods for larvae and first-, second-, third-, fourth-, and fifth-instar nymphs fed on pigs were 7, 9, 15, 11, 15, and 15 d, respectively. The majority of infected and all uninfected ticks required only one blood meal from pigs to molt. Mean weights for unfed second-, third-, and fourth-instar nymphs and males and females were 0.50, 0.67, 3.07, 3.63, and 5.91 mg, respectively.


Nectar sources and age structure in a population of Aedes provocans (Diptera: Culicidae). Gonotrophic-age structure of a population of Aedes provocans (Walker) and nectar sources used by adults were studied for 2 yr at a field site near Belleville, Ontario, Canada. Females emerged during a short period, and aging of the population was highly synchronous. Complete parity of the population was achieved within about 17 d in 1978 and 27 d in 1979. Some females completed as many as four gonotrophic cycles. This synchronous pattern of population aging is compared with patterns in other species of snow-melt Aedes, which typically age much more gradually. The pattern of synchronous aging permitted estimation of daily mortality rates from an index of population size derived from human-bait catches; peaks in the biting index were related to each gonotrophic cycle in the population. Nectar sources for adults were ranked according to abundance and the extent to which they were used by Ae. provocans, permitting a coarse, semiquantitative estimate of preferences. Ae. provocans obtained nectar from the extrafloral nectaries of one species and the floral nectaries of 19 species of angiosperms. Shrubs and trees, especially of the Rosaceae (primarily species of Prunus), were particularly important as nectar sources and bloomed concurrently with the appearance of nulliparous females. Sharp declines in the population of Ae. provocans were associated with the cessation of blooming of these plant species. It is hypothesized that the highly synchronous pattern of gonotrophic aging in Ae. provocans was attributable, in part, to the ready availability of nectar sources and bloodmeal hosts near breeding sites.


Scanning electron microscopy of egg hatching of Anopheles albimanus (Diptera: Culicidae). Scanning electron and light microscopic observations showed that egg hatching in Anopheles albimanus Wiedemann is aided by a chisel-shaped spine. This hatching tooth is surrounded by a thin flexible membrane fixed to a groove in the head of the larvae. Increased intracranial pressure may force the spine against the egg shell until a fissure is produced. Further opening of the egg is achieved by movements of the head and the entire body of the larva.


Leishmania infantum MON-98 isolated from naturally infected Phlebotomus langeroni (Diptera: Psychodidae) in El Agamy, Egypt. Leishmania infantum zymodeme MON-98 was isolated in El Agamy, Egypt. A total of 15 (1.07%) Leishmania-like infections in the anterior midgut and in the head was found in 1,405 Phlebotomus langeroni (Nitzulescu); none of 1,785 Phlebotomus papatasi (Scopoli) was found infected. Four of the 15 cultures (26.7%) were indistinguishable from a reference L. infantum MON-98 strain using cellulose acetate electrophoresis. The isolation and identification of L. infantum MON-98 from naturally infected P. langeroni confirms that this species of sand fly is the vector of visceral leishmaniasis in El Agamy.


Tests for the existence of genetic determination or conditioning in host selection by Anopheles albimanus (Diptera: Culicidae). The existence of sympatric populations within Anopheles albimanus Wiedemann with specific host preferences and the question of whether host selection has a genetic basis or is a learned characteristic were investigated. Progeny of wild females collected from corrals or human bait were reared in an insectary. F1 females were fed on a cow or on a human host, allowed to oviposit, and then were released in an experimental hut divided into three compartments. The side rooms occupied by two human or one calf baits were connected by a "funnel-like" cone with the central room in which mosquitoes were released. Females were released at 2000 hours and recaptured the next morning at 0600 hours. A fixed proportion of mosquitoes selected either host (approximately 65% cow and 35% human), irrespective of their parental origin or source of the first blood meal. The data indicate that the existence of cryptic populations with anthropophilic habits is unlikely and that a "learned" host selection also may be ruled out.


Use of an aquatic light trap for monitoring larval population of Culex quinquefasciatus (Diptera: Culicidae). An aquatic light trap was evaluated in wading pools placed in a greenhouse as a method of sampling populations of mosquito larvae. Three replicated experiments examined the effect of the color of a Cyalume light source and the vertical placement of the trap within the water column. Traps placed with the entrance funnel opening at the surface of the water collected significantly more fourth-instar Culex quinquefasciatus than did those with the entrance submerged. When traps were placed near the surface of the water, those with blue, yellow, and white light sticks, as well as unlighted control traps, collected approximately the same number of larvae. Therefore, a small change in trap position was more important than the presence of a light source in the effectiveness of this aquatic light trap as a sampling device for mosquito larvae.


Evaluation of devices for removing attached Rhipicephalus sanguineus (Acari: Ixodidae). Three types of forceps and a commercially available device, the Tick Solution, were used to remove adult brown dog ticks, Rhipicephalus sanguineus (Latreille), from dogs. The Tick Solution proved least effective at removing ticks, requiring significantly more removal attempts compared with forcep-removal methods. Medium-tipped angled forceps provided the best overall performance. Other advantages and disadvantages of the devices are discussed.


In the genes or in the stars? Children's competence to consent. Children's competence to refuse or consent to medical treatment or surgery tends to be discussed in terms of the child's ability or maturity. This paper argues that the social context also powerfully influences the child's capacity to consent. Inner attributes and external influences are discussed using an analogy of the genes and the stars.


Baby marrow: ethicists and privacy.

Baby marrow: ethicists and privacy. A family had a child in large part to use its marrow in the hopes of saving the life of an older child afflicted with leukaemia. Public response from medical ethicists was negative. This paper argues that what the family did was not clearly wrong and that the ethicists should not have made public pronouncements calling the morals of the family into question.


'Aid-in-dying' and the taking of human life. In several US states, the legalisation of euthanasia has become a question for voters to decide in public referenda. This democratic approach in politics is consistent with notions of personal autonomy in medicine, but the right of choice does not mean all choices are morally equal. A presumption against the taking of human life is embedded in the formative moral traditions of society; human life does not have absolute value, but we do and should impose a strict burden of justification for exceptions to the presumption, as exemplified by the moral criteria invoked to justify self-defence, capital punishment, or just war. These criteria can illuminate whether another exception should be carved out for doctor-assisted suicide or active euthanasia. It does not seem, in the United States at any rate, that all possible alternatives to affirm the control and dignity of the dying patient and to relieve pain and suffering, short of taking life, have been exhausted. Moreover, the procedural safeguards built into many proposals for legalised euthanasia would likely be undone by the sorry state of the US health care system, with its lack of universal access to care, chronic cost-containment ills, a litigious climate, and socioeconomic barriers to care. There remains, however, common ground in the quest for humane care of the dying.


Legislation on euthanasia: recent developments in The Netherlands. Recently, new developments took place in the Dutch debate on the legislation of euthanasia. After a brief account of that debate, the article discusses a new government proposal for legislation in this field, which was submitted to the Dutch parliament in November 1991. This proposal relates not only to euthanasia but also to some other medical decisions concerning the end of life. The author concludes that, for several reasons, it is unsatisfactory.


Measuring the ethical sensitivity of medical students: a study at the University of Toronto. An instrument to assess 'ethical sensitivity' has been developed. The instrument presents four clinical vignettes and the respondent is asked to list the ethical issues related to each vignette. The responses are classified, post hoc, into the domains of autonomy, beneficence and justice. This instrument was used in 1990 to assess the ethical sensitivity of students in all four medical classes at the University of Toronto. Ethical sensitivity, as measured by this instrument, is not related to age or grade-point average. Sensitivity increases between the 1st and 2nd year and then decreases throughout the rest of undergraduate medical training, such that the 4th-year students identify fewer issues than those entering medical school. Students expressing a career choice of family medicine identify more issues than their peers. Several problems with the use of the instrument and the interpretation of the data were found. Nonetheless, these findings, if reproducible, are important and their meaning needs further discussion.


Learning to see: moral growth during medical training. During medical training students and residents reconstruct their view of the world. Patients become bodies; both the faults and the virtues of the medical profession become exaggerated. This reconstruction has moral relevance: it is in part a moral blindness. The pain of medical training, together with its narrowness, contributes substantially to these faulty reconstructions. Possible improvements include teaching more social science, selecting chief residents and faculty for their attitudes, helping students acquire communication skills, and helping them deal with their own pain. Most importantly, clearer moral vision requires time and scope for reflection.


When loyalties are divided between teachers and patients. Three situations are described where a junior doctor is required by his consultant to do something that he thinks is not in the patient's best interests. The dilemma is explored from the perspective of patients' interests being the doctor's first concern; of the importance of respect for medical teachers, and of the implications of an apprenticeship model of postgraduate medical training.


Stress.

Stress. 'Stress' is a widely used word in clinical practice, the biological sciences and everyday life; but one which has little real value, serving mainly to confuse and confound rational thought. Whether it is described in terms of stimulus, response, or a combination of the two the definitions of stress are invariably found to be circular. We should stop using the word 'stress' and instead discuss specific stimuli or responses as appropriate. The author suggests that 'pressure' and 'tension' might provide suitable substitutes for everyday clinical practice.


X inactivation as a mechanism of selection against lethal alleles: further investigation of incontinentia pigmenti and X linked lymphoproliferative disease. Thirty-one females with incontinentia pigmenti (IP), 42 controls, and 11 females from four families segregating for X linked lymphoproliferative disease (XLP) were studied for evidence of skewed X inactivation by analysis of methylation at sites in the HPRT, PGK, and M27 beta (DXS255) regions of the X chromosome. Extensive skewing of X inactivation was present in blood from 4/42 (9.5%) control females and 11/31 (35%) of those with IP. This frequency of skewed inactivation was seen in both familial and sporadic cases of IP. Analysis of inactivation in mother/daughter pairs, both affected and control subjects, showed no familial consistency of pattern, arguing against specific mutations being associated with particular patterns of inactivation. In the only informative family where both mother and daughter were affected by IP and showed skewed inactivation, the IP mutation was on the active X chromosome. This argues against cell selection during early embryogenesis being the explanation for the skewed inactivation observed. These data confirm that skewed inactivation of one X is observed in lymphocytes from a significant minority of normal females, and is seen with raised frequency in IP heterozygotes. It is not, however, a universally observed phenomenon, and the relationship of X inactivity to the IP mutation appears to be complex. In the case of XLP, though skewed X inactivation patterns are seen in most disease carriers, the frequency with which this phenomenon occurs in normal females renders it an unreliable diagnostic marker for XLP carriers.


Chromosomal localisation of a pseudoautosomal growth gene(s). Although recent molecular studies in patients with sex chromosome aberrations are consistent with a growth gene(s) being present in the pseudoautosomal region (PAR), the precise location has not been determined. In this report, we describe a Japanese boy and his mother with an interstitial deletion in Xp22.3 and review the correlation between genotype and stature in six cases of partial monosomy of the PAR. The results indicate that the region from DXYS20 to DXYS15 is the critical region for the putative growth gene(s).


The acrocallosal syndrome and Greig syndrome are not allelic disorders. Acrocallosal syndrome is an autosomal recessive form of polysyndactyly associated with mental retardation and agenesis of the corpus callosum. There have been suggestions that it is allelic to the Greig cephalopolysyndactyly syndrome. Linkage analysis, using flanking markers, shows this suggestion is unlikely to be correct.


Multipoint mapping of adult onset polycystic kidney disease (PKD1) on chromosome 16. Analysis of genetic linkage data in 33 adult onset polycystic kidney (ADPKD) families was carried out using probes for the D16S85, D16S84, and D16S94 loci. The data set of 33 families shows no evidence of genetic heterogeneity since one unlinked family was previously excluded. Two point linkage analysis showed maximum likelihood values of the recombination fraction of 0.07 for ADPKD and D16S85 (lod score 18.78), 0.02 for ADPKD and D16S84 (lod score 7.55), and 0.00 for ADPKD and D16S94 (lod score 6.73). Multipoint analysis showed a maximum likelihood order of tel-D16S85-0.06-D16S84-0.02-(PKD1, D16S94)-cen with a multipoint lod score of 32.16. Analysis of rare recombinants lying close to PKD1 gave results consistent with this order.


Cartilage-hair hypoplasia in Finland: epidemiological and genetic aspects of 107 patients. Cartilage-hair hypoplasia (CHH) is an autosomal recessive form of metaphyseal chondrodysplasia characterised by short limbed short stature, hypoplastic hair growth, and impaired cell mediated immunity and erythrocyte production. The syndrome is exceptionally prevalent among the Finns and among the Old Order Amish in the United States; sporadic cases have been reported from other countries. An epidemiological and genetic study of CHH in Finland showed 107 patients, 46 males and 61 females, in 85 families. Eighteen of them had died, seven before the age of 1 year. The living patients ranged in age from 1 to 51 years, median 21 years. The incidence was estimated to be 1:23,000 live births. Consanguinity was found in two families and interfamilial relationships in 20 families. Geographical distribution of the birth places of the patients and their great grandparents showed accumulation in a small area in western Finland and regional clusters were seen in other parts of the country as well. The result of the segregation analysis was in accordance with recessive inheritance with reduced penetrance.


Screening for phenylketonuria in a totalitarian state. Living under a totalitarian regime has many effects on the structure, way of thinking, and relations in a society. However, it is the impact on neonatal genetic screening that we discuss in this paper. Genetic screening functions at the interface between health services and society at large. Being involved for over a decade in setting up the Bulgarian PKU screening programme, we have had to deal with ways and attitudes which may be difficult for the western mind to grasp. Yet comprehension is very much needed in the new world we are trying to create.


Weyers' ulnar ray/oligodactyly syndrome and the association of midline malformations with ulnar ray defects. We describe a two generation family with variable ulnar and radial ray reduction and midline craniofacial abnormalities. The features suggest a diagnosis of Weyers' ulnar ray/oligodactyly syndrome originally described in two isolated cases. Syndromes of ulnar ray reduction are briefly reviewed and the relationship between limb bud and midline development discussed.


X inactivation patterns in females with Alport's syndrome: a means of selecting against a deleterious gene? The patterns of X chromosome inactivation in 43 females from families segregating classic Alport's syndrome (AS) (X linked hereditary nephritis with deafness) have been analysed. AS carrier females have a most variable clinical course. The aim of the study was to establish whether there was any correlation between the X inactivation pattern of a carrier female and the severity of her disease. No correlation was found in DNA derived from peripheral blood lymphocytes. However, it remains possible that differential patterns of X inactivation may occur in the tissues affected by AS, namely the basement membrane of the kidney, eye, and ear.


New dysmorphic features in Rubinstein-Taybi syndrome. We report a new case of Rubinstein-Taybi syndrome with a hypoplastic right kidney, persistent pulmonary hypertension, and mitral valve regurgitation. Other pertinent features included broad thumbs, broad big toes, syndactyly of the third and fourth fingers bilaterally, beaked nose, broad columella of the nose, patent ductus arteriosus, and motor and mental retardation. The testes were descended. The 3 month old patient had delayed motor and mental development corresponding to a 1 month old infant.


18p- syndrome and hypopituitarism.

18p- syndrome and hypopituitarism. A patient is described with 18p- syndrome and hypopituitarism. This is the first patient with this syndrome who has been shown to benefit from growth hormone therapy. Patients with this syndrome who have growth deficiency should be considered for evaluation for hypopituitarism, if the quality of their lives would improve with an increase in stature.


Bilateral retinopathy, aplastic anaemia, and central nervous system abnormalities: a new syndrome? A male infant was found to have bilateral exudative retinopathy at 6 months of age. A month later severe aplastic anaemia was diagnosed, eventually leading to the infant's death. Additional features of this seemingly new syndrome were intrauterine growth retardation, fine sparse hair, fine reticulate skin pigmentation, ataxia because of cerebellar hypoplasia, cerebral calcifications, extensor hypertonia, and progressive psychomotor retardation.


Unknown syndrome: nasal hypoplasia, sparse hair, truncal obesity, genital hypoplasia, and severe mental retardation. A 4 year old girl is described with severe mental retardation, peculiar face with nasal hypoplasia, sparse hair, genital hypoplasia, truncal obesity, puffy hands, and small feet with complete cutaneous syndactyly of the second and third toes.


Design characteristics for drug nebulizers. Drug nebulizers should be designed to produce an aerosol which efficiently targets drug to the respiratory tract. In this article we review the basic principles of aerosol generation from both jet and ultrasonic nebulizers, and the factors governing respiratory tract penetration and deposition. We review methods for accurate measurement of aerosol dose and size, with emphasis on evaporative effects and the implications to drug nebulizer design. We identify three forms of drug aerosol waste attributable to: generation of non-respirable aerosol, losses to the environment, and dead volume solution; and we consider how each may be minimized through good nebulizer design. Finally, we compare the relative merits of jet and ultrasonic nebulizers, and conclude by predicting a new trend in future drug nebulizer therapy.


Interference problems and screening in NMR and MRI. A pragmatic approach to interference in NMR and MRI systems is presented with the objective of raising the awareness of problems associated with larger installations. The basic premise is that an installation is a system composed of interconnected sub-systems, each with its own idiosyncracies. Consequently all problems should be considered from this view-point. Practical warnings and solutions are given along with simple mathematical equations to permit one to calculate some interference effects. Most problems are associated with RF and gradient sub-systems, so the main content deals with degradation of the NMR signal by noise and coherent RF interference and with the interaction of sub-systems. Attention is drawn to the correct identification of the source of a problem, and the importance of a well engineered solution. 'Quick-fix repairs' can lead to very baffling problems when the system is reconfigured for a different experiment.


Biparietal diameter: an alternative measure of head growth in the low-birthweight infant. Reliability and validity of biparietal diameter (BPD) compared with head circumference (HC) measurement as an index of cranial growth was assessed. A significant correlation between BPD and HC (r = 0.857; p less than 0.0001) and an interobserver reliability of 92% were found. Infants' age and sex had independent effects on BPD growth rate. Very sick infants had a lower increase in BPD rate than healthy controls. It is suggested that in sick premature infants, when the head is encumbered by various types of apparatus, this technique might prove more feasible than HC measurement.


Medical device regulations in the New Europe. We are now in 1992, the year of the 'Completion of the Internal Market'. Big changes in the ways in which medical devices will be controlled in Europe are on the way, but many healthcare professionals are unaware of these changes and what they will mean to them. This article explains the moves that are now under way to harmonize medical device legislation throughout Europe and the many features, new to the UK, that they will introduce.


Effects of skin blood flow and temperature on skin--electrode impedance and offset potential: measurements at low alternating current density. Skin--electrode impedance was determined at 100 Hz and 1 kHz between two disposable electrodes, 5 cm apart, at current densities < 65 microA.cm-2. Measurements were made on the volar skin of the forearm during cooling on cardiopulmonary bypass, and on the dorsum of the foot in the absence of skin blood flow during aortic aneurysm repair. Both the resistive and reactive components of the skin-electrode impedence showed an inverse linear relationship to temperature between 26 and 36 degrees C. The magnitude of the impedance change was different for each patient studied; resistance changes ranged from 0.03 to 23.2 k omega. Degrees C-1 at 100 Hz and from 0.03 to 2.7 k omega. Degrees C-1 at 1 kHz, while reactance changes ranged from 0.4 to 2.1 k omega. Degrees C-1 at 100 Hz and from 0.04 to 0.18 k omega. Degrees C-1 at 1 kHz. Changes in skin-electrode impedance were not due to changes in skin blood flow. There was no consistent change in offset potential with temperature. Although the skin-electrode impedance increases as temperature falls, it is concluded that temperature effects at the skin-electrode interface are not responsible for the observed failure of evoked electromyography during clinical monitoring of neuromuscular function.


Extracellular proteins as a potential marker of active Staphylococcus aureus infection in bone. The potential of extracellular protein antigens of Staphylococcus aureus as markers of infection of bone was investigated by immunoblotting. Serum from patients with S. aureus bone infection showed levels of IgG antibodies to a preparation of soluble extracellular proteins of 17-81 kDa which were significantly higher than those found in serum from normal controls. By contrast, immunoblots of various whole cell or cell wall-derived antigens gave complex patterns of response which were unsuitable for positive diagnosis of S. aureus bone infection.


Portable maximum respiratory pressure measurement--a comparison with laboratory techniques. We have evaluated a new, hand-held, electronic device to measure maximal respiratory pressures, and compared its performance in normal subjects against two pre-existing methods. This new device produces accurate, reproducible results and has the advantages of easy use and portability, which allow it to be used at the patient's bedside, outpatient clinic or pulmonary function laboratory.


The production of fatty acid modifying enzyme (FAME) and lipase by various staphylococcal species. Eighty-six strains encompassing 11 species of coagulase-negative staphylococci were examined for the production of fatty acid modifying enzyme (FAME) and lipase. Staphylococcus schleiferi and S. saprophyticus most closely resembled S. aureus in that 80% of the strains produced both enzymes. In contrast, no strains of S. lugdunensis and S. haemolyticus tested produced these enzymes. S. simulans was unusual in that eight of 10 strains produced FAME, but only one produced lipase. Among the other species the proportion of strains producing both enzymes ranged from 10 to 60%. Generally there was a strong correlation between FAME and lipase production.


An evoked compound electromyogram simulator with external microprocessor control facility. A circuit for an evoked electromyogram simulator is described, which produces a biphasic triangular waveform similar to the evoked compound action potential seen during clinical quantitative neuromuscular monitoring. The device can produce a fading train-of-four sequence, which can be controlled using a single externally-derived voltage. The simulator is useful for bench-testing of closed loop muscle relaxant administration systems, and for teaching aspects of neuromuscular monitoring in anaesthesia.


The esterification of fatty acids by Staphylococcus aureus fatty acid modifying enzyme (FAME) and its inhibition by glycerides. Fifty-five randomly selected Staphylococcus aureus strains were examined for fatty acid modifying enzyme (FAME) production. Of these, 20.4% did not elaborate the enzyme. Amongst the remaining strains, the lowest level produced in culture was 0.1 unit/10(9) cocci and the maximum was 2.01 U/10(9) cocci; the median level was 0.4 U/10(9) cocci. In a series of straight-chain saturated fatty acids with 11-24 carbons, all could be esterified by FAME. However, those with 15-19 carbons were generally better substrates than the others. For a particular chain length, the unsaturated forms were better substrates than the saturated form. Triglycerides with unsaturated fatty acid side chains were potent inhibitors of FAME. Diglycerides were almost as active as triglycerides, but monoglycerides were much less inhibitory. FAME was purified by gel filtration followed by hydrophobic interaction chromatography on hexyl agarose. FAME and lipase may have a role in determining the survival of S. aureus in lesions.


The production of a bactericidal monoglyceride in staphylococcal abscesses. The treatment of abscess homogenates with calcium ionophores stimulated the production of a bactericidal lipid with properties indistinguishable from those of a previously unidentified bactericidal lipid that had been detected in staphylococcal abscesses. The lipid was identified as a monoglyceride by thin layer chromatography. It resembled the unidentified lipid in that it had a high specific activity, exhibited differential activity, was inhibited by Staphylococcus aureus delta toxin, lecithin and Ca++, and its activity was reduced by oxidation. Stimulation of monoglyceride production by calcium ionophore requires the joint presence of components from the sedimented and supernatant fractions of abscess homogenates, and was not produced if boiled homogenate was used. The addition of verapamil interfered with the production of monoglyceride in homogenates treated with calcium ionophore. Monoglyceride was produced only in abscess homogenates and not in homogenates of other normal tissues or tissues taken from mice infected with S. aureus. Calcium ionophore could be replaced by inositol triphosphate, suggesting that monoglyceride production involved the release of calcium from intracellular stores. The 2-monoglyceride was the form originally produced in abscess homogenates, but this spontaneously isomerized to the 1-monoglyceride. The fatty-acid moiety of the monoglyceride consisted primarily of 16:0 and 16:1 fatty acids.


Evaluation of the PhP system for biochemical-fingerprint typing of strains of Salmonella of serotype Typhimurium. The Phene Plate (PhP) system of biochemical fingerprinting of bacteria is a computerised typing system, based on quantitative measurements of the kinetics of several biochemical reactions of bacteria grown in liquid medium in microtitration plates. For each isolate tested, it yields a biochemical fingerprint comprising several kinds of quantitative data which are useful for establishing similarities among strains with a personal-computer program. In this study, a set of 16 specific substrates was chosen to differentiate strains of Salmonella of serotype Typhimurium. The system was evaluated for its typability, reproducibility and discriminatory power in tests with a collection of 100 epidemiologically unrelated Typhimurium strains and results were compared with those obtained by phage typing. At an identity level of 0.980, strains were assigned by this method to 51 biochemical phenotypes (BPTs), giving a diversity index of 0.963 and a resolution index of 0.210. In contrast, 24 phage types (PTs) were identified among these isolates (a diversity index of 0.901). The combined use of biochemical fingerprinting by the PhP system and phage typing discriminated 82 phenotypes (a diversity index of 0.994). Stability of markers in each of the methods was also evaluated after subculture of 20 strains for 21 consecutive days. Only nine biochemical reactions were found that were subject to small, but measurable, changes for at least one isolate. These changes slightly decreased the mean similarity coefficients among strains but the overall BPTs of the strains showed changes in four strains (20%). In contrast, eight strains (40%) showed changes in their PTs after this treatment. It is concluded that the PhP system is a highly discriminatory and reproducible method for typing Typhimurium strains. It is easy to perform, and may be used alone or in combination with phage typing in epidemiological studies of Typhimurium strains.


Assessment of an infra-red non-contact sensor for routine skin temperature monitoring: a preliminary study. The accuracy and reproducibility of a new non-contact sensor for monitoring skin temperature was examined. Thirty measurements taken by the device were compared with those taken by a commonly used thermocouple contact sensor. The result was a very high correlation coefficient (r = 0.9999). This accuracy was achieved with the probe held at an angle of 90 degrees 1 cm from the skin. Changes in angle and distance were found to contribute to measurement error. Little difference was found between 39 pairs of measurements taken of the left and right sides of subjects. However, intra-subject variability was noted with respect to the dermotomal segmental fields. Inter-tester reliability analysis resulted in a correlation of r = 0.937 involving two independent testers and 26 pairs of measurements. These preliminary data will be used for power calculations to study further the device which we found to be simple to operate, portable, and practical for routine clinical use. This sensor may have applications in the diagnosis of nerve and vascular disorders and in prospective monitoring of skin conditions such as bony areas at risk of pressure ulcers.


Design and evaluation of an instrument to measure microcirculatory blood flow and oxygen saturation simultaneously. There are compelling clinical advantages in being able to monitor, simultaneously and continuously, blood oxygen saturation and tissue perfusion from the same volume of tissue. We describe the design of a new instrument capable of combining both functions. It uses a laser diode at 805 nm to give a blood flow index and oxygenation information at that wavelength, and a pulsed LED at 660 nm to complete the estimation of oxygen saturation. By using a compensating photodetector these readings can be made relatively insensitive to sampling site. After calibrating the instrument on forehead sites it reliably read the oxygen saturation of sites on the thigh with a bias of -0.2% and a precision of +/- 1.7% relative to an IL 282 CO-oximeter.


The use of biochemical fingerprinting, phage typing and antimicrobial-susceptibility testing in the detection of epidemic strains of Salmonella of serotype Typhimurium in Iran. A collection of 86 strains of Salmonella of serotype Typhimurium isolated from children with gastroenteritis in Tehran, Iran was examined for biochemical phenotype, phage type and antibiotic-resistance pattern. Twenty-seven biochemical phenotypes (BPTs), 14 discrete phage types (PTs) and 18 resistotypes (RTs) were identified. Fifty-three strains (62%) belonged to two major and probably related BPTs, whereas the other 33 isolates belonged to less common BPTs. The two predominant BPTs contained 26 strains of the same PT and 23 strains of the same RT. Different PTs and RTs of strains with similar BPT were sometimes observed, possibly reflecting antibiotic pressures in Iran. These results suggest that two major "clones" of Typhimurium strains are particularly common in Iran and, although each method alone adequately detected these and other less common "clones", biochemical fingerprinting provided additional information about relationships among strains.


Treatment of experimental infections of mice with bacteriophages. Bacteriophages for Acinetobacter baumanii, Pseudomonas aeruginosa and Staphylococcus aureus were tested in experimental infections of mice to investigate their potential for the treatment of infections of man. As few as 10(2) particles of an acinetobacter phage protected mice against 5 LD50 (1 x 10(8)) of a virulent strain of A. baumanii, and phage was demonstrated to have multiplied in the mice. A pseudomonas phage protected mice against 5 LD50 of a virulent strain of P. aeruginosa, with a PD50 of 1.2 x 10(7) particles. A staphylococcal phage failed to protect mice infected with a strain of S. aureus. These studies support the view that bacteriophages could be useful in the treatment of human infections caused by antibiotic-resistant strains of bacteria.


Production of haemolysis and its correlation with enterotoxicity in Aeromonas spp. A total of 147 clinical and environmental isolates of Aeromonas that included 14 A. hydrophila, 60 A. sobria and 73 A. caviae strains was tested for haemolysin production and its correlation with enterotoxicity; 108 isolates produced beta-haemolysis. For A. hydrophila and A. sobria, titres of haemolysin were 16-128 HU/ml and for A. caviae, 16-64 HU/ml. In the ileal loop test, 82 (55.8%) strains of Aeromonas spp. produced enterotoxin. Of the beta-haemolytic strains, 72.7% of A. hydrophila, 58.6% of A. sobria and 68.6% of A. caviae isolates caused fluid accumulation in rabbit ileal loops. One strain each of alpha-haemolytic A. sobria and A. caviae, one of non-haemolytic A. sobria and nine of non-haemolytic A. caviae also caused a secretory response. The beta-haemolytic strains caused significantly more (p < 0.05) fluid accumulation than the alpha- and non-haemolytic isolates regardless of their species designation. The remaining 65 (44.2%) isolates belonging to the three species included alpha-, beta- and non-haemolytic strains: they failed to cause fluid accumulation in the initial experiments but did so after one to three consecutive passages through rabbit ileal loops. Two alpha- and 13 non-haemolytic strains switched to production of beta-haemolysis when they showed positive ileal loop reactions. However, on repeated subcultures or on storage in the laboratory, all of them reverted to their original haemolytic character and no longer produced enterotoxic activity.


Association of Haemophilus ducreyi with cell-culture lines. The association of Haemophilus ducreyi with epithelial cell cultures was studied by light microscopy, electronmicroscopy and viable counts. Associated organisms were engulfed by epithelial cells and sequestered from the cell-surface environment. Large numbers of organisms within epithelial cells appeared to induce cell lysis and release of H. ducreyi. Such a mechanism occurring in vivo may assist H. ducreyi to evade the bactericidal action of polymorphonuclear leucocytes and may explain some of the tissue damage seen in genital ulcers caused by H. ducreyi.


A pyrolysis mass spectrometry study of the non-pigmented Prevotella species. Collection strains (21) and non-pigmented clinical isolates (96) provisionally identified as Prevotella spp. were classified numerically on the basis of pyrolysis mass spectrometry (PMS) data and reaction patterns in conventional tests (CTRPs) for volatile and non-volatile fatty acids, pre-formed enzymes and biochemical activity. PMS and CTRP classifications were compared with a previous classification based on visual analysis of SDS-PAGE patterns. Although the order of clusters differed, cross-tabulation of cluster membership revealed strong correlations between classifications. Cluster membership in the PMS classification correlated particularly well with SDS-PAGE results. CTRP clusters corresponded largely to the recognised species of Prevotella, but PMS and SDS-PAGE divided two species into sub-groups: two in P. buccae and five in P. veroralis. The latter subgroups could be discriminated by small but consistent differences in CTRPs. An undesignated, well differentiated cluster of strains appeared closest to the main group of P. buccae strains in PMS and CTRPs. B. (P.) capillus could not be distinguished from P. buccae; these species are regarded as synonymous. Strains of P. zoogleoformans and B. (P.) pentosaceus were well separated from other strains in PMS. A complex comprising clusters of P. disiens, P. oralis, P. veroralis, P. loescheii and a further undesignated group similar to P. melaninogenica was well differentiated from P. buccae and P. oris in PMS; clusters corresponding to P. bivia, P. corporis, P. intermedia and P. denticola formed another complex.


Appraisal of the total blood lymphocyte proliferation assay as a diagnostic tool in screening for tuberculosis. The total blood lymphocyte proliferation assay (TLP) was evaluated as a screening test for infection with Mycobacterium tuberculosis and was compared with the tuberculin (Mantoux) skin test. The results of TLP assays performed on 33 patients with tuberculosis and 37 non-tuberculous subjects were compared with results of skin tests performed in the previous year. There was a high correlation between skin test responses and TLP responses to PPD which was statistically significant. The sensitivity, specificity and the predictive value of a positive test were also similar for the skin test and TLP test. These findings suggest that the TLP test is as effective in screening for M. tuberculosis infection as tuberculin skin testing. Future research leading to further simplification of the TLP method may lead to it replacing intradermal skin testing.


A simple and rapid method for the detection and identification of mycobacteria using mycobactin. A system was developed for the identification of mycobacteria such as Mycobacterium tuberculosis and M. avium, by thin layer chromatography of 55Fe-labelled mycobactin. Approximately 2 x 10(3) mycobacteria were detected within 24 h and little operator time or skill was required. M. avium, M. intracellulare and M. scrofulaceum were found to have lower requirements for iron than other mycobacteria and this may influence their growth in host organisms.


Initial organ localisation of blood-borne Candida albicans in a rat model of disseminated candidosis. The rat was evaluated as an experimental model for disseminated candidosis by quantitating blood clearance and initial organ localisation of 3H-leucine-labelled Candida albicans after intravenous injection into the tail or portal vein. Viable or formalin-killed blastoconidia or viable blastoconidia with germ tubes were injected into experimental animals. Blood and tissue samples were obtained up to 24 h after injection and processed for liquid scintillation counting (to determine the distribution of labelled yeasts) and quantitation of viable organisms. Yeasts were cleared rapidly after intravenous (i.v.) injection by either route, i.e., < 5% of the radioactivity was detected in the blood after 5 min. The liver and lung were the major organs that sequestered blood-borne yeasts 1 h after tail vein injection (42.5 SD 15% and 41.4 SD 6.4% of labelled yeasts injected, respectively). However, injections via the portal vein resulted in trapping of the yeasts predominantly by the liver. Recovery of radioactivity and viable yeasts from all organs except the kidneys decreased with time. Overall, the results indicated that the rat might serve as a reliable model for short-term studies on organ distribution and thus contribute to our understanding of tissue trophism in candidosis.


Determination of the time of ovulation in chimpanzees by measurement of LH, estrone sulfate, and pregnanediol 3 alpha-glucuronide in urine: comparison with serum hormone patterns. The concentrations of LH, total estrogens, and pregnanediol 3 alpha-glucuronide (PdG) were determined by specific radioimmunoassays on daily overnight urine samples obtained in 13 menstrual cycles of six adult female chimpanzees during the periods of increasing, maximal, and decreasing tumescence of the perineal sex skin. The peaks of estrogens and LH and the rise in PdG in urine accurately reflected the peaks of estradiol-17 beta and LH and the subsequent rise in progesterone in the serum of the same animals during the same menstrual cycles, and can be used to predict and verify the occurrence of ovulation, thus avoiding the repeated tranquilizations necessary to obtain daily blood samples.


Quantification and excretion profiles of pteridines in primate urine. Biopterin, 6-hydroxymethyl-pterin, isoxanthopterin, neopterin and, pterin were quantified in stress-free collected spontaneous morning urine samples from Callithrix jacchus, Saguinus fuscicollis, Saguinus labiatus, Saimiri sciureus, Presbytis entellus, Cercopithecus albogularis, Cercocebus torquatus, Macaca fascicularis, Hylobates concolor, Pongo pygmaeus, and Gorilla gorilla. In most species, biopterin was the most frequent urinary pteridine followed by neopterin. Sex differences in biopterin and neopterin excretion were observed in Gorilla gorilla and Pongo pygmaeus. Pterin and isoxanthopterin were only present in minor concentrations. 6-hydroxymethyl-pterin was barely detectable and not present in the urine of Saguinus labiatus, Saimiri sciureus, and both male Gorilla gorilla and Pongo pygmaeus.


Age determination of common marmosets (Callithrix jacchus) by radiographic examination of skeletal development. Seventy-four animals were examined radiographically to determine the skeletal development of the common marmoset (Callithrix jacchus) from 6 months of age. Twenty-one epiphyses were examined and five stages of ossification were described for each. The animals were divided into nine groups, according to age, and a table of the stage of ossification and age was produced, which may be used for determining the age of animals of unknown history.


The baboon model under anesthesia for in vivo cerebral blood flow studies using single photon emission computed tomographic (SPECT) techniques. Single photon emission computed tomography of the brain can be useful in animal experimentation directed toward cerebral conditions. A well established and understood baboon model, necessarily under anesthesia, could be especially valuable in such investigations. Six normal baboons were studied under various anesthetic agents and their combinations: ketamine, thiopentone, pentobarbitone, and halothane. Cerebral blood flow (CBF) studies were performed with 99mTc-HMPAO. CBF effects from various anesthesia were detected, requiring careful choice of the anesthesia for cerebral investigations.


Identification of two subclasses of IgA in the chimpanzee (Pan troglodytes). Chimpanzee secretory immunoglobulin A (SIgA) was separated into two fractions by chromatography using the terminal galactose-binding lectin Jacalin. The SIgA fraction bound by Jacalin was cleaved by Haemophilus influenzae IgA1 protease, whereas the SIgA nonbinding fraction was not cleaved. It is proposed that these fractions represent IgA1 and IgA2 subclasses because the presence or absence of galactose-terminal oligosaccharides (Jacalin binding) and susceptibility or resistance to IgA1 protease are properties that define human IgA1 and IgA2 subclasses.


Spontaneous cardiomyopathy and nephropathy in the owl monkey (Aotus sp.) in captivity. Clinical and pathologic data were reviewed for 72 owl monkeys that died between January 1987 and May 1990 at the Center for Reproduction and Conservation of Nonhuman Primates in Iquitos, Peru. Tissue samples from 39 animals were examined. Hypertrophic cardiac disease (51% of animals examined), dilative cardiomyopathy (26%), and nephropathy (87%) were the most common diagnoses. The incidence of all three diseases appeared to increase with time in captivity. Nephropathy was less severe in colony-born animals.


Membrane transport properties of L-2,4-diaminobutyrate revisited. We explore here the special structural features of certain diamino acid analogs which may account for their intense accumulation into tumor cells, first observed for the Ehrlich ascites tumor cell for in vitro suspensions. This accumulation, which ordinarily occurs mainly by system A for its dipolar substrates, is so intense for these tripolar diamino acids accompanied by the chloride ion as well as by displacement, especially of the cellular potassium ion, that the cells swell to several times their normal volume and osmotic destruction arises. These structural features receive our reconsideration here toward understanding the energization of amino acid transport into cells, also toward identifying among them possible superior 11C-labeled tracers for imaging tumors in situ by positron emission tomography (PET). The possibility of therapeutic, perhaps osmotic, destruction of inoperable terminal gliomas by topical application of such amino acids by microdialysis has also been considered in preliminary tests by one of us (G.R.) and his associates.


Sarcolemmal calcium binding sites in heart: I. Molecular origin in "gas-dissected" sarcolemma. Calcium in the myocardial cell is highly compartmentalized and a fast, an intermediate, a slow and a nonexchangeable calcium pool have been described. The fast pool contains 66% of the total cell exchangeable calcium in cultured neonatal rat heart cells with a t1/2 of less than 1.5 sec. Though the cellular origin of this fast pool is unknown, its rapidity and its displacement by La3+ most likely places it at the sarcolemma or at least in rapid equilibrium with the sarcolemma. We isolated the sarcolemma of cultured neonatal rat heart cells using the gas-dissection technique, which yields a pure sarcolemmal preparation in less than a second, thereby precluding membrane changes which might occur during conventional plasma membrane isolation. We determined the calcium binding characteristics of these membranes, using an on-line technique to monitor 45Ca, which allows measurement of 45Ca binding characteristics in the presence of unbound 45Ca. Two classes of calcium binding sites were determined: (i) Kd of 13 microM, capacity 7 nmol/mg and (ii) Kd of 1.1 mM, capacity of 84 nmol/mg. To assess the molecular origin of the sarcolemmal calcium binding we treated the membranes with a variety of enzymes. Protease or neuraminidase treatment did not cause large changes in these parameters. Simultaneous treatment with two different phospholipases C or the extraction of the lipids with isopropanol resulted in a dramatic loss of the low-affinity binding sites. These results, in association with previously defined sarcolemmal phospholipid distribution, places the low-affinity binding sites at the cytoplasmic leaflet. The physiological implication of this localization as it pertains to cellular calcium exchange is discussed.


Sarcolemmal calcium binding sites in heart: II. Mathematical model for diffusion of calcium released from the sarcoplasmic reticulum into the diadic region. We present a model for predicting the temporal and spatial dependence of [Ca] in the cardiac subsarcolemmal diadic region (cleft), following Ca release from the "feet" of the sarcoplasmic reticulum. This region is modeled as a disc 10 nm thick, 430 nm in radius, with or without Ca binding sites and open at its periphery to the cytosol. [Ca] is computed for three diffusion coefficients (100, 20 and 4% of aqueous diffusion), following release of a 20-msec square pulse sufficient to produce 50% maximal contractile force, or repetitive release (400/min) of such pulses. Numerical solutions are obtained for the general diffusion/binding problem and analytic solutions for the case of no binding sites. For the middle value of diffusion coefficient, and in the absence of binding sites, [Ca] rises to approximately 1.5 mM in 20-msec and then falls to approximately 0.1 microM in less than 3 msec. Adding binding sites reduces peak [Ca] to approximately 0.6 mM but prolongs its decline, requiring approximately 200 msec to reach 20 microM. For repetitive release [Ca] is greater than 100 microM for roughly half of each cycle. Two major implications of the predicted [Ca] are: (i) The effect of Ca binding sites on [Ca] will cause Ca efflux from the cleft via the Na-Ca exchanger (Km(Ca) approximately 20 microM) to continue at a significant level for greater than 200 msec. (ii) The time constant for inactivation of release from the "feet" must be much greater than for activation if Ca-induced Ca release is to continue for greater than 1-2 msec.


Three-dimensional analysis of cell nucleus structures visualized by confocal scanning laser microscopy. Studies of the three-dimensional (3-D) organization of cell nuclei are becoming increasingly important for the understanding of basic cellular events such as growth and differentiation. Modern methods of molecular biology, including in situ hybridization and immunofluorescence, allow the visualization of specific nuclear structures and the study of spatial arrangements of chromosome domains in interphase nuclei. Specific methods for labelling nuclear structures are used to develop computerized techniques for the automated analysis of the 3-D organization of cell nuclei. For this purpose, a coordinate system suitable for the analysis of tri-axial ellipsoidal nuclei is determined. High-resolution 3-D images are obtained using confocal scanning laser microscopy. The results demonstrate that with these methods it is possible to recognize the distribution of visualized structures and to obtain useful information regarding the 3-D organization of the nuclear structure of different cell systems.


Whole-cell potassium current in rabbit corneal epithelium activated by fenamates. Rabbit corneal epithelium contains a large-conductance, potassium-selective channel, which is a major contributor to the whole-cell current. In perforated-patch recordings of the macroscopic current, the isolated cells studied had resting voltages of -41 +/- 20 mV and capacitances of 5.8 +/- 2.6 pF (mean +/- SD for n = 255). Activation of the channels was weakly voltage dependent. They opened at about -100 mV and reached an open probability of about 0.2 at +100 mV. The current was blocked by millimolar concentrations of external Ba2+ and quinidine. Diltiazem also blocked when applied to the external surface of the membrane. Nonsteroidal anti-inflammatory agents of the fenamate group were powerful activators of the channel at submillimolar concentrations when applied either to the inside or the outside of the channels. The mechanism of action which leads to his activation is not yet known.


Automated microdensitometry of nucleolar organizer regions using microspectrophoto-microscopy. Nucleolar organizer regions (NORs) are major sites of ribosomal RNA synthesis, providing an index of transcriptional activity and possibly determining the malignant status of cells. Difficulties lie in quantifying them. This study reports a methodology to assist in the standardization of the assessment of interphase NORs. Regenerating hepatocytes, which have increased rRNA synthesis, were chosen as a model to test automated microdensitometry for silver-stained NORs. Quantification employed a microspectrophoto-microscope as a microdensitometer. Significant differences in silver-stained NORs in hepatocytes were recorded among treatment/fixative groups. As the quantitative method avoids subjective observer error and thus improves the accuracy of measurement, it would potentially have routine application to diagnostic pathology.


SEM studies of surfaces hidden within bulk tissue: a simple technique to control the position and orientation of dry fracture planes. A simple, reliable method for the exposure of specific structures hidden within bulk tissue for viewing by SEM is described. The method employs dry fracture after critical-point drying and differs from other dry fracture methods in that the fracture plane is 'engineered' by the experimenter, thus overcoming the tendency for natural planes of weakness within the specimen exclusively to define the fracture plane. The technique retains the simplicity of the very high-quality in situ cellular relationships normally associated with random dry fracture. Attention is given to novel means of circumventing the artefacts that are normally a problem with dry fracture techniques.


Fixation for biological ultrastructure. I. A viscometric analysis of the interaction between glutaraldehyde and bovine serum albumin. The increase in viscosity resulting from mixing concentrated solutions of albumin with dilute glutaraldehyde has been investigated. The viscosity changes are slow at first, very sensitive to small changes in glutaraldehyde concentration, and non-linear with time. The cross-linking of the albumin by glutaraldehyde seems to be retarded by the weak mechanical shear forces produced by the viscometer. The significance of these findings to the events in tissue fixation is discussed.


Fixation for biological ultrastructure. II. Cross-linking of bovine serum albumin by nanosecond pulses of ionizing radiation. Very large doses of ionizing radiation were delivered quickly to concentrated albumin solutions by pulses of 500 keV in air. The electrons penetrated the aluminium foil bottom of the test cell and into the solution. A dose of 4.6 Mrad (4.6 x 10(4) Gy) produced a gel in the albumin solution comparable to the long-term effect of 0.36% glutaraldehyde in the same albumin solution. The cross-links created by the radiation leading to gel formation are probably irreversible and quite different from those leading to gelation in the glutaraldehyde-albumin reaction. Single large pulses of ionizing radiation may be useful for fast fixation of cells and tissues for microscopy.


Family support, physical impairment, and adherence in hemodialysis: an investigation of main and buffering effects. Patient noncompliance is a pervasive problem among end-stage renal disease (ESRD) patients. Previous studies have implicated social support as an important correlate of adherence behavior in other chronic illness groups, but little research has examined this relationship in a hemodialysis population. The present study examined the main and interactive effects of social support in the family and illness-related physical impairment with regard to patient compliance in a sample of 78 hemodialysis patients. Results indicated that patients holding perceptions of a more supportive family environment exhibited significantly more favorable adherence to fluid-intake restrictions than did patients reporting less family support. Family support was not associated with adherence to dietary restrictions. The effect of family support on fluid-intake adherence was not moderated by level of physical impairment. This pattern suggests that the influence of support on adherence is more attributable to a main or direct effect, as opposed to a buffering process in the face of increased physical impairment.


Elevated serum dehydroepiandrosterone sulfate levels in practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs. Serum dehydroepiandrosterone sulfate (DHEA-S) levels were measured in 270 men and 153 women who were experienced practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs, mental techniques practiced twice daily, sitting quietly with the eyes closed. These were compared according to sex and 5-year age grouping to 799 male and 453 female nonmeditators. The mean DHEA-S levels in the TM group were higher in all 11 of the age groups measured in women and in 6 of 7 5-year age groups over 40 in men. There were no systematic differences in younger men. Simple regression using TM-group data revealed that this effect was independent of diet, body mass index, and exercise. The mean TM-group levels measured in all women and in the older men were generally comparable to those of nonmeditator groups 5 to 10 years younger. These findings suggest that some characteristics of TM practitioners are modifying the age-related deterioration in DHEA-S secretion by the adrenal cortex.


The effects of biofeedback-assisted relaxation on cell-mediated immunity, cortisol, and white blood cell count in healthy adult subjects. The effect of biofeedback-assisted relaxation on cell-mediated immunity, cortisol, and white blood cell count was investigated in healthy adults under low-stress conditions. Fourteen subjects were trained with biofeedback-assisted relaxation for 4 weeks, while 17 subjects were controls. The group trained in relaxation techniques showed increased blastogenesis, decreased white blood cell count, due to decreased neutrophils, and no change in cortisol in comparison to the control group. Subjects with lower initial anxiety scores and forehead muscle tension levels showed larger increases in blastogenesis and larger decreases in neutrophils than subjects with higher initial anxiety and muscle tension levels.


Sex roles, occupational roles, and symptom-reporting: a test of competing hypotheses on sex differences. The sick-role, fixed-role obligations, symptom-reporting, and nurturant-role hypotheses of sex differences in utilization of health services and symptom-reporting were tested against each other. Fifty-one nontraditional college students completed the Cornell Medical Index (CMI), the Bem Sex Role Inventory, and questions regarding their employment status. Employment status and feminine characteristics emerged as the best predictors of symptom-reporting on the CMI and suggested that the sick-role hypothesis may be empirically superior to the others.


Adherence to exercise interventions in the treatment of hypercholesterolemia. The goals of this study were to determine the rate of adherence to exercise treatment of hypercholesterolemia and to identify personality and demographic factors associated with adherence. Of the 31 subjects entering the 26-week program, 12 attended 80% or more of the scheduled sessions. Adherence was positively associated with the perceived seriousness of hypercholesterolemia, the expectation of benefit from treatment, and depressed feelings of helplessness and hopelessness. Negative associations were identified between adherence and the perception of health status being under the control of chance or of powerful others. Older subjects were more likely to be adherers at 8 and 16 weeks but not at 26 weeks.


The patterning of psychological attributes and distress by "job strain" and social support in a sample of working men. As a test of the "job strain" (job demands-control) model, 297 healthy men aged 30-60 were recruited at eight New York City worksites. The association among job demands and control, social support, and psychological outcomes was tested using both ANCOVA and moderated multiple regression, controlling for demographic variables. The job strain model was supported by various psychological outcome measures, with workers in "active" jobs reporting the highest level of Type A behavior, job involvement, and positive attributional style, workers in "low-strain" jobs reporting the lowest job dissatisfaction and trait anxiety, workers in "passive" jobs reporting the most external locus of control and trait anxiety, and workers in "high-strain" jobs reporting the highest job dissatisfaction. Low social support was associated with greater symptomatology, and a significant three-way interaction (demands x control x support) for job dissatisfaction was observed. While selection of subjects into jobs may partially explain these findings, the results support the hypothesis that working conditions influence psychological attributes and distress.


The effects of nonconcurrent and concurrent relaxation training on cardiovascular reactivity to a psychological stressor. Eight patients in a cardiac rehabilitation program, after exposure to two psychological stressors approximately equivalent with respect to cardiovascular reactivity, were given nonconcurrent progressive muscle relaxation training and retested for reactivity. They were then provided with relaxation training concurrently with one of the stressors and exposed again to the two stressors. No significant effects for nonconcurrent progressive muscle relaxation training were detected. Concurrent training, in contrast, produced reductions in both systolic and diastolic blood pressure. Reductions resulting from training on the target stressor showed little tendency to generalize to the nontarget stressor; the discrimination was particularly well defined for systolic blood pressure. We conclude that muscle relaxation techniques are maximally effective in reducing reactivity to psychological stressors when relaxation training is provided concurrently with the stressor. Our findings further suggest that to inculcate the relaxation response reliably across different situations, specific training to enhance generalization may be needed.


Dental visit satisfaction in a group of adults aged 50 years and over. Studies have found that utilization of dental services is generally less common than utilization of medical services, particularly by older persons. Because satisfied dental patients were found to be greater users of the service than nonsatisfied patients, it was decided to investigate the correlates of dental visit satisfaction in older subjects. Predictions that satisfaction would be positively related to regular use of dental services and negatively related to dental anxiety were confirmed. The results also suggested that older dental patients have different expectations of their dentists than younger ones.


Modularity of the slit protein. Characterization of a conserved carboxy-terminal sequence in secreted proteins and a motif implicated in extracellular protein interactions. Since our characterization of the slit cDNA sequence, encoding a protein secreted by glial cells and involved in the formation of axonal pathways in Drosophila, we have discovered that the protein contains two additional sequence motifs that are highly conserved in a variety of proteins. A search of the GenPept database with the 73 amino acids at the carboxy terminus of slit revealed that this region contains significant similarity to a carboxy-terminal domain found in six other exported proteins. This observation has allowed us to define a new carboxy-terminal protein motif. In addition, comparisons with a 202 amino acid domain residing between epidermal growth factor (EGF) repeats in slit shows this region to be conserved in laminin, agrin and perlecan and, strikingly, also to lie between EGF repeats in both agrin and perlecan. Our analysis suggests this motif is involved in mediating interactions among extracellular proteins. Consistent with our previous characterization of the slit protein, both new motifs are found only in extracellular proteins. The identification of these two conserved motifs in slit reveals that the entire 1469 amino acids of the protein are made up of modular regions similar to those conserved in other extracellular proteins.


Predicting protein secondary structure with a nearest-neighbor algorithm. We have developed a new method for protein secondary structure prediction that achieves accuracies as high as 71.0%, the highest value yet reported. The main component of our method is a nearest-neighbor algorithm that uses a more sophisticated treatment of the feature space than standard nearest-neighbor methods. It calculates distance tables that allow it to produce real-valued distances between amino acid residues, and attaches weights to the instances to further modify the the structure of feature space. The algorithm, which is closely related to the memory-based reasoning method of Zhang et al., is simple and easy to train, and has also been applied with excellent results to the problem of identifying DNA promoter sequences.


Characterization of "native" apomyoglobin by molecular dynamics simulation. We have used molecular dynamics simulation methods to study the structure and fluctuations of "native" apomyoglobin in aqueous solution for a period of greater than 0.5 nanosecond. This work was motivated by the recent attempts of Hughson et al. to characterize the structure and motion of both this molecule and the less compact, acid stabilized I stage, using methods of pulsed H/2H exchange. The study of these systems provides new insights into protein folding intermediates and our simulation has yielded a detailed model for structure and fluctuations in apomyoglobin which complements the experimental studies. We find that local (short-time) fluctuations agree well with fluctuations observed for the holoprotein in aqueous solution, as well as results from the crystallographic B-factors. In addition, the structural features we observe for native apomyoglobin are very similar to the holoprotein, in basic agreement with the findings of Hughson et al. By examining larger-scale motions, developing only over timescales in excess of a 100 picoseconds, we are able to identify conformationally "labile" and "non-labile" regions within native apomyoglobin. These regions correspond extremely well to those identified in the nuclear magnetic resonance experiments as unstable and stable "folding subdomains" in the I state of apomyoglobin. Overall we find that helices A, B, E, G and H show the least amount of motion and helices C, D and F move substantially over the timescales examined. The major motions, and the primary difference between the holo and apo structures as we have observed them, are due to the shifting motion of helices C, D and F into the vacant heme cavity. We also find that motions at the interface of helical segments can be large, with one important exception being the chain segment connecting helices G and H. This segment of chain interacts with the conformationally "non-labile" helix A to form a relatively rigid subdomain composed of helices A, G and H. We believe that these findings provide direct support for the suggestion of Hughson et al. that helices A, G and H constitute a compact subdomain that remains in a native-like conformation as the protein begins to unfold in environments of decreasing pH.