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.     

Conservation of motifs within the unusually variable polypeptide sequences of type I restriction and modification enzymes

Type I restriction enzymes comprise three subunits encoded by genes designated hsdR, hsdM, and hsdS; S confers sequence specificity. Three families of enzymes are known and within families, but not between, hsdM and hsdR are conserved. Consequently, interfamily comparisons of M and R sequences focus on regions of putative functional significance, while both inter- and intrafamily comparisons address the origin, nature and role of diversity of type I restriction systems. We have determined the sequence of the hsdR gene for EcoA, thus making available sequences of all three hsd genes of one representative from each family. The predicted R polypeptide sequences share conserved regions with one superfamily of putative helicases, so-called ‘DEAD box’ proteins; these conserved sequences may be associated with the ATP-dependent translocation of DNA that precedes restriction. We also present hsdM and hsdR sequences for EcoE, a member of the same family as EcoA. The sequences of the M and R genes of EcoA and EcoE are at least as divergent as typical genes from Escherichia coli and Salmonella, perhaps as the result of selection favouring diversity of restriction specificities combined with lateral transfer among different species.     

Development and regeneration of the retinotectal map in goldfish: a computational study

We present a simple computational model to study the interplay of activity-dependent and intrinsic processes thought to be involved in the formation of topographic neural projections. Our model consists of two input layers which project to one target layer. The connections between layers are described by a set of synaptic weights. These weights develop according to three interacting developmental rules: (i) an intrinsic fibre-target interaction which generates chemospecific adhesion between afferent fibres and target cells; (ii) an intrinsic fibre-fibre interaction which generates mutual selective adhesion between the afferent fibres; and (iii) an activity-dependent fibre-fibre interaction which implements Hebbian learning. Additionally, constraints are imposed to keep synaptic weights finite. The model is applied to a set of eleven experiments on the regeneration of the retinotectal projection in goldfish. We find that the model is able to reproduce the outcome of an unprecedented range of experiments with the same set of model parameters, including details of the size of receptive and projective fields. We expect this mathematical framework to be a useful tool for the analysis of developmental processes in general. <br>     

The alpha- and beta-tubulin folding pathways

The alpha-beta tubulin heterodimer is the subunit from which microtubules are assembled. The pathway leading to correctly folded alpha- and beta-tubulins is unusually complex: it involves cycles of ATP-dependent interaction of newly synthesized tubulin subunits with cytosolic chaperonin, resulting in the production of quasi-native folding intermediates, which must then be acted upon by additional protein cofactors. These cofactors form a supercomplex containing both alpha- and beta-tubulin polypeptides, from which native heterodimer is released in a GTP-dependent reaction. Here, we discuss the current state of our understanding of the function of cytosolic chaperonin and cofactors in tubulin folding.     

Induction of tumor necrosis factor alpha in human neuronal cells by extracellular human T-cell lymphotropic virus type 1 Tax.

To examine the role of human T-lymphotropic virus type 1 (HTLV-1) Tax1 in the development of neurological disease, we studied the effects of extracellular Tax1 on gene expression in NT2-N cells, postmitotic cells that share morphologic, phenotypic, and functional features with mature human primary neurons. Treatment with soluble HTLV-1 Tax1 resulted in the induction of tumor necrosis factor alpha (TNF-alpha) gene expression, as detected by reverse-transcribed PCR and by enzyme-linked immunosorbent assay. TNF-alpha induction was completely blocked by clearance with anti-Tax1 monoclonal antibodies. Furthermore, cells treated with either a mock bacterial extract or with lipopolysaccharide produced no detectable TNF-alpha. Synthesis of TNF-alpha in response to soluble Tax1 occurred in a dose-dependent fashion between 0.25 and 75 nM and peaked within 6 h of treatment. Interestingly, culturing NT2-N cells in the presence of soluble Tax1 for as little as 5 min was sufficient to result in TNF-alpha production, indicating that the induction of TNF-alpha in NT2-N does not require Tax1 to be continually present in the culture medium. Treatment of the undifferentiated parental embryonal carcinoma cell line NT2 with soluble Tax1 did not result in TNF-alpha synthesis, suggesting that differentiation-dependent, neuron-specific factors may be required. These results provide the first experimental evidence that neuronal cells are sensitive to HTLV-1 Tax1 as an extracellular cytokine, with a potential role in the pathology of HTLV-1-associated/tropical spastic paraparesis.     

Sequence of an expressed human beta-tubulin gene containing ten Alu family members

The complete sequence of a functionally expressed human beta-tubulin gene (5 beta) is presented. The amino acid sequence encoded by this gene constitutes a distinct isotype, differing from a previously described human beta-tubulin sequence at 21 positions throughout the polypeptide chain. The beta-tubulin coding sequence in 5 beta is interrupted by three intervening sequences of 1014, 117 and 4826 nucleotides. The largest of these contains ten members of the Alu family of middle repetitive sequences. Together, these regions account for sixty percent of this intervening sequence. Two of the Alu elements are juxtaposed head to tail, and share the same flanking direct repeat. The ten Alu sequences are substantially divergent, both from each other and from an Alu consensus sequence, and several contain deletions of up to half the entire sequence.     

Number and evolutionary conservation of alpha- and beta-tubulin and cytoplasmic beta- and gamma-actin genes using specific cloned cDNA probes

A partial library of cloned human DNA was screened for sequences represented on and specific to the X chromosome. The library was constructed from Bam HI-digested human DNA from cells with X chromosome polyploidy, and was cloned in pBR322. The screening was performed by individually hybridizing ³²P-labeled cloned plasmids to Southern blots containing Bam HI-digested DNA from mouse-human hybrid cells having the human X chromosome and from derivative hybrids lacking the human X. Of 45 clones assayed, 33 contained sequences homologous to ones represented many times on the X. In situ hybridization to metaphase chromosomes demonstrated that at least four of these clones were homologous to autosomes as well. Only one of the 18 clones of this kind tested cross-hybridized with another. Two recombinant plasmids were shown to be derived from the X chromosome and to be X chromosome-specific by three criteria: they hybridized to a single band in the Southern blots of Bam HI-digested DNA from hybrid cells containing the X chromosome; they hybridized to a band of the same molecular weight as did the inserted DNA fragment; and they showed a dosage effect when hybridized to Southern blots of Bam HI-digested DNA from XY and XXX cells. One of these hybridized as a single-copy or low-order reiterated sequence in a Cot analysis using male DNA as driver. Our methods can be applied to the identification of any chromosome-specific clone. The two X-specific clones identified here should be useful in investigating the mechanism of X inactivation and in isolating a Barr body.     

The effect of pentobarbital on the antinociceptive action of morphine in morphine-tolerant and non-tolerant rats

The interaction of sodium pentobarbital with morphine sulfate in both morphine-tolerant and non-tolerant rats was investigated using the tail-compression test for analgesia. Male Sprague-Dawley rats (300–350 g) were given pentobarbital (4, 8, or 16 mg/kg) 5 min before morphine (2, 4, 6, or 8 mg/kg). Control animals received two saline injections, or pentobarbital plus saline, or saline plus morphine. All injections were subcutaneous. Prior to the first injection, a baseline nociceptive threshold was determined for each rat by applying a modified micrometer to its tail and increasing the pressure until a squeak was elicited. Test readings were taken every half-hour for 2 hr beginning 30 min after the second injection. For the chronic studies, animals were first made tolerant to morphine by the administration of the narcotic twice a day for 3 days, increasing the dose from 10 to 50 mg/kg/injection. Identical testing procedures were then followed with these rats except that the test dose of morphine given on day 4 was in the range 8–128 mg/kg. It was found that Na pentobarbital, in the subanesthetic doses used, had neither antinociceptive nor hyperalgesic properties. Furthermore, the barbiturate had no effect on the antinociceptive action of morphine in either morphine-tolerant or non-tolerant rats.     

The properties of immobilized caldolysin, a thermostable protease from an extreme thermophile

Caldolysin, the extracellular thermostable metal-chelator-sensitive lytic protease from Thermus T-351 was immobilized to Sepharose 4B, CM-cellulose, and controlled pore glass (CPG). Although protein binding efficiencies were high (96, 88, and 95%), some loss of enzyme activity occurred on immobilization (26, 69, and 89%). The pH optimum of both CM-cellulose and CPG-immobilized Caldolysin was decreased by about one pH unit. The K(m) for Sepharose-Caldolysin was unchanged with respect to the free protease, while those for CM-cellulose-Caldolysin and CPG-Caldolysin were lower by approximately one order of magnitude. Immobilization to both Sepharose and CM-cellulose increased the thermostability of Caldolysin at high temperatures, while CPG-Caldolysin was less thermostable than the free protease.