Antibody to herpes simplex virus type 2 as serological marker of sexual lifestyle in populations.

OBJECTIVES--To examine the epidemiology of antibody to herpes simplex virus type 2 and to assess its suitability as a serological marker of sexual behaviour in populations with high and low prevalences. DESIGN--Cross sectional survey. SETTING--Department of genitourinary medicine and blood donation centre in central London. SUBJECTS--Representative sample of 869 patients attending department between November 1990 and December 1991, and 1494 consecutive blood donors attending for donation between February and April 1992. METHOD--Participants had a blood sample taken for antibody testing with a novel type specific assay and completed a questionnaire. RESULTS--Prevalence of antibody differed significantly between the two groups (188/833 (22.7%) clinic attenders; 102/1347 (7.6%) blood donors). In both populations antibody was strongly associated with sex, sexual orientation, years of sexual activity, number of lifetime sexual partners, and past infection with sexually transmitted diseases after other factors were controlled for. Only 130 (45%) of all those with antibody had symptoms suggestive of genital herpes, and 79 (27.4%) had had genital herpes diagnosed. Of those without antibody to herpes simplex viruses type 1 and 2, 8.0% reported genital blisters or sores and 1.1% had had genital herpes diagnosed by a doctor. CONCLUSIONS--The strong relation between herpes simplex virus type 2 and sexual lifestyle suggests that the presence of antibody to the virus may be suitable for use as an objective, serological marker of patterns of sexual behaviour in different populations. These data show that only a minority of those infected with herpes simplex virus type 2 have a diagnosis of genital herpes or express clinical symptoms, making serological determinants of infection essential for epidemiological studies.     

Single anion channels reconstituted from cardiac mitoplasts

Ion channels from sheep cardiac mitoplast (inverted inner mitochondrial membrane vesicle) preparations were incorporated into voltage-clamped planar lipid bilayers. The appearance of anion rather than cation channels could be promoted by exposing the bilayers to osmotic gradients formed by Cl⁻ salts of large, relatively imperment, cations at a pH of 8.8. Two distinct activities were identified. These comprised a multisubstate anion channel of intermediate conductance (∼60 pS in 300vs. 50mm choline Cl, ∼100 pS in symmetric 150mm KCl), and a lower-conductance anion channel (∼25 or ∼50 pS in similar conditions), which only displayed two well-defined substates, at ∼25 and ∼50% of the fully open state. The larger channels were not simple multiples of the lower-conductance channels, but both discriminated poorly, and to a similar extent, between anions and cations (P_Cl ⁻/P_choline ⁺ ∼12, P_Cl ⁻/P_K ⁺∼8). The lower-conductance channel was only minimally selective between different anions (P_{NO 3} ⁻ (1.0)=P_Cl ⁻>P_Br ⁻>P_I ⁻>P_SCN ⁻(0.8)), and its conductance failed to saturate even in high (>1.0 M) activities of KCl. The channels were not obviously voltage dependent, and they were unaffected by 0.5 mM SITS, H₂O₂, propranolol, quinine or amitriptyline, or by 2 mM ATP, or by variations in pH (5.5–8.8). Ca²⁺ and Mg²⁺ did not alter single channel activity, but did modify single current amplitudes in the lower-conductance channel. This effect, together with voltage-dependent substate behavior, is described in the following paper.     

mtDNA diversity in rhesus monkeys reveals overestimates of divergence time and paraphyly with neighboring species

Reconstructions of the human-African great ape phylogeny by using mitochondrial DNA (mtDNA) have been subject to considerable debate. One confounding factor may be the lack of data on intraspecific variation. To test this hypothesis, we examined the effect of intraspecific mtDNA diversity on the phylogenetic reconstruction of another Plio- Pleistocene radiation of higher primates, the fascicularis group of macaque (Macaca) monkey species. Fifteen endonucleases were used to identify 10 haplotypes of 40-47 restriction sites in M. mulatta, which were compared with similar data for the other members of this species group. Interpopulational, intraspecific mtDNA diversity was large (0.5%- 4.5%), and estimates of divergence time and branching order incorporating this variation were substantially different from those based on single representatives of each species. We conclude that intraspecific mtDNA diversity is substantial in at least some primate species. Consequently, without prior information on the extent of genetic diversity within a particular species, intraspecific variation must be assessed and accounted for when reconstructing primate phylogenies. Further, we question the reliability of hominoid mtDNA phylogenies, based as they are on one or a few representatives of each species, in an already depauperate superfamily of primates.      

Hatching plasticity in a Southeast Asian tree frog mitigates submergence-induced mortality

Environmentally cued hatching has been well-documented in amphibians in response to a wide range of abiotic and biotic factors. The hatching of terrestrial amphibian eggs in response to flooding may be basal within the group, but amphibian lineages in tropical Asia and sub-Saharan Africa have not received as much attention as their Neotropical counterparts. We investigated submergence-induced hatching in Feihyla hansenae, a Rhacophorid tree frog with terrestrial eggs. We quantified natural rates of clutch submergence at our study site in Thailand. Using submergence experiments, we found that embryos are capable of hatching early to escape flooding, and that failure to hatch results in mortality. Among the embryos that were able to hatch early, only the earliest, youngest hatchlings experienced a trade-off in body size that persisted for 6 days, while later, older hatchlings were not significantly smaller than spontaneous hatchlings under control conditions. By incorporating our natural and experimental data into Monte Carlo methods to simulate and compare survival probabilities with and without hatching plasticity, we found an overall 3.1% increase in submergence survival due to hatching plasticity. Our findings support the idea that flooding-induced hatching is widespread across amphibians with terrestrial eggs and highlight the importance of researching understudied tropical regions. As climate change is projected to affect rainfall patterns, the ability of embryos to escape abiotic egg-stage threats may be an indicator of species' ability to flexibly navigate a changing environment.     

Population dynamics of a meiotic/mitotic expansion model for the fragile X syndrome.

A model to explain the mutational process and population dynamics of the fragile X syndrome is presented. The mutational mechanism was assumed to be a multipathway, multistep process. Expansion of CGG repeats was based on an underlying biological process and was assumed to occur at two time points: meiosis and early embryonic development (mitosis). Meiotic expansion was assumed to occur equally in oogenesis and spermatogenesis, while mitotic expansion was restricted to somatic, or constitutional, alleles of maternal origin. Testable hypotheses were predicted by this meiotic/mitotic model. First, parental origin of mutation is predicted to be associated with the risk of a woman to have a full mutation child. Second, "contractions" seen in premutation male transmissions are predicted not to be true contractions in repeat size, but a consequence of the lack of mitotic expansion in paternally derived alleles. Third, a portion of full-mutation males should have full-mutation alleles in their sperm, due to the lack of complete selection against the full-mutation female. Fourth, a specific premutation-allele frequency distribution is predicted and differs from that based on models assuming only meiotic expansion. Last, it is predicted that approximately 65 generations are required to achieve equilibrium, but this depends greatly on the expansion probabilities.     

Grain dust and the lungs.

Grain dust is composed of a large number of materials, including various types of grain and their disintegration products, silica, fungi, insects and mites. The clinical syndromes described in relation to exposure to grain dust are chronic bronchitis, grain dust asthma, extrinsic allergic alveolitis, grain fever and silo-filler''s lung. Rhinitis and conjunctivitis are also common in grain workers. While the concentration and the quality of dust influence the frequency and the type of clinical syndrome in grain workers, host factors are also important. Of the latter, smoking is the most important factor influencing the frequency of chronic bronchitis. The role of atopy and of bronchial hyperreactivity in grain dust asthma has yet to be assessed. Several well designed studies are currently being carried out in North America not only to delineate the frequency of the respiratory abnormalities, the pathogenetic mechanisms and the host factors, but also to establish a meaningful threshold limit concentration for grain dust.     

Mode of initiation of cell infection with sludge-associated poliovirus.

Association with sludge solids did not allow poliovirus to enter cells other than through the normal receptor-mediated route. This implies that the infectivities of sludge-encapsulated virions are masked until their exposure permits binding to cell surface receptors.     

Identification of detergents as components of wastewater sludge that modify the thermal stability of reovirus and enteroviruses.

The agent in wastewater sludge previously shown to reduce the heat required to inactivate reovirus (R. L. Ward and C. S. Ashley, Appl. Environ. Microbiol. 34:681--688, 1977) was "separated" from other sludge components and analyzed by infrared spectroscopy. The infrared spectrum of this material was quite similar to the spectra of commercial anionic detergents, and subsequent analyses of the fractionated sludge samples revealed that anionic detergents in sludge were copurified with the virucidal activity. Further measurements on the virucidal activities of specific detergents revealed that ionic detergents reduce the heat required to inactivate reovirus, that cationic detergents are more active than anionic, and that nonionic detergents are inactive. Several detergents were also shown to protect poliovirus and other enteroviruses against inactivation by heat. These results indicate that ionic detergents are the major component in wastewater sludge that reduce the thermal stability of reovirus and, in addition, that detergents are able to protect enteroviruses against heat.