Prostitution and risk of HIV: male partners of female prostitutes.

OBJECTIVE--To describe risk behaviours for infection with HIV in male sexual partners of female prostitutes. DESIGN--A cross sectional study. SETTING--Genitourinary medicine clinic, St Mary''s Hospital, London. SUBJECTS--112 self identified male sexual partners of female prostitutes: 101 who reported commercial sexual relationships only, five who reported non-commercial relationships only, and six who reported both commercial and non-commercial relationships. MAIN OUTCOME MEASURES--Reported risk behaviours for infection with HIV. RESULTS--Of the 40 men who had had previous HIV tests or were tested during the study, two (5%) were infected with HIV. Of the men who would answer the questions, 34/94 reported having sex with other men, 2/105 reported using injected drugs, 8/105 had a history of blood transfusion, 14/108 reported a past history of gonorrhoea, 44/102 reported paying for sex abroad, and 8/92 said that they had also been paid for sex. Of the 55 men who reported paying for vaginal intercourse in the past year, 45 (82%) said that they had always used a condom. In contrast, of the 11 non-paying partners of prostitutes, only two (18%) reported ever using a condom with their partners. CONCLUSIONS--Men who have sex with female prostitutes cannot be assumed to be at risk of infection with HIV only by this route: homosexual contact may place them at greater risk. Despite the heterogeneity among male sexual partners of prostitutes, patterns of use of condoms were uniform when they were considered as a reflection of the type of relationship a man had with a female prostitute rather than a consequence of an individual''s level of risk.     

Dextran production by Leuconostoc mesenteroides in the presence of a dextranase producing yeast, Lipomyces starkeyi

Summary A new process for the production of small size dextran is developed in which dextran is produced by cultures of Leuconostoc mesenteroides in the presence of a partially constitutive mutant of Lipomyces starkeyi producing dextranase. Mixed cultures were examined by scanning electron microscopy with ruthenium to show the effects of the mixed culture on low molecular weight dextran (M.W. of 5,000 – 100,000) formation. The presence of the size variation in dextran was confirmed by gel permeation chromatography.     

Recruitment of the Rhesus soleus and medial gastrocnemius before, during and after spaceflight

Electromyograms were recorded from the soleus and medial gastrocnemius muscles and tendon force from the medial gastrocnemius muscle of 2 juvenile Rhesus monkeys before, during and after Cosmos flight 2229 and of ground control animals. Recording sessions were made while the Rhesus were performing a foot pedal motor task. Preflight testing indicated normal patterns of recruitment between the soleus and medial gastrocnemius, i.e. a higher level of recruitment of the soleus compared to the medial gastrocnemius during the task. Recording began two days into the spaceflight and showed that the media gastrocnemius was recruited preferentially over the soleus. This observation persisted throughout the flight and for the 2 week period of postflight testing. These data indicate a significant change in the relative recruitment of slow and fast extensor muscles under microgravity conditions. The appearance of clonic-like activity in one muscle of each Rhesus during flight further suggests a reorganization in the neuromotor system in a microgravity environment.     

Alternative Oxidase Activity in Tobacco Leaf Mitochondria (Dependence on Tricarboxylic Acid Cycle-Mediated Redox Regulation and Pyruvate Activation)

Transgenic Nicotiana tabacum (cv Petit Havana SR1) containing high levels of mitochondrial alternative oxidase (AOX) protein due to the introduction of a sense transgene(s) of Aox1, the nuclear gene encoding AOX, were used to investigate mechanisms regulating AOX activity. After purification of leaf mitochondria, a large proportion of the AOX protein was present as the oxidized (covalently associated and less active) dimer. High AOX activity in these mitochondria was dependent on both reduction of the protein by DTT (to the noncovalently associated and more active dimer) and its subsequent activation by certain [alpha]-keto acids, particularly pyruvate. Reduction of AOX to its more active form could also be mediated by intramitochondrial reducing power generated by the oxidation of certain tricarboxylic acid cycle substrates, most notably isocitrate and malate. Our evidence suggests that NADPH may be specifically required for AOX reduction. All of the above regulatory mechanisms applied to AOX in wild-type mitochondria as well. Transgenic leaves lacking AOX due to the introduction of an Aox1 antisense transgene or multiple sense transgenes were used to investigate the potential physiological significance of the AOX-regulatory mechanisms. Under conditions in which respiratory carbon metabolism is restricted by the capacity of mitochondrial electron transport, feed-forward activation of AOX by mitochondrial reducing power and pyruvate may act to prevent redirection of carbon metabolism, such as to fermentative pathways.     

Studies on the import and processing of the alternative oxidase precursor by isolated soybean mitochondria

Import of the synthetic precursor of the alternative oxidase from soybean was shown to be dependent on a membrane potential and ATP. The membrane potential in soybean mitochondria may be formed either by respiration through the cytochrome pathway, or through the alternative oxidase pathway with NAD⁺-linked substrates. Import of the alternative oxidase precursor in the presence of succinate as respiratory substrate was inhibited by KCN. Import in the presence of malate was insensitive to KCN and SHAM added separately, but was inhibited by KCN and SHAM added together (inhibitors of the cytochrome and alternative oxidases respectively). Import of the alternative oxidase was accompanied by processing of the precursor to a single 32 kDa product in both cotyledon and root mitochondria. This product had a different mobility than the two alternative oxidase bands detected by immunological means (34 and 36 kDa), suggesting that the enzyme had been modified in situ. When the cDNA clone of the alternative oxidase was modified by a single mutation (–2 Arg changed to –2 Gly), the processing of the precursor was inhibited.     

Serotonergic Regulation of Acetylcholine Release in Rat Frontal Cortex

Abstract: The extent to which serotonin regulates the activity of cortically projecting cholinergic neurons was studied using in vivo microdialysis to monitor interstitial concentrations of acetylcholine in the frontal cortex of freely moving rats. Systemic administration of the serotonin release-inducing agent fenfluramine (3 or 10 mg/kg, i.p.) increased acetylcholine release by 110–130%. The fenfluramine-induced increase in acetylcholine release was significantly attenuated by pretreatment with the selective serotonin uptake inhibitor fluoxetine (10 mg/kg, i.p.). Pretreatment with the selective dopamine D₁ receptor antagonist SCH-23390 (0.3 mg/kg, s.c.) failed to prevent the fenfluramine-induced increase in acetylcholine release. In contrast, the serotonin 5-HT_2A receptor antagonist ketanserin (5 mg/kg, i.p.) blocked fenfluramine-induced increases in acetylcholine release. In contrast to previous studies that have concluded that serotonin has inhibitory actions on cortical acetylcholine release, the present results indicate that fenfluramine increases cortical acetylcholine release in vivo by its ability to enhance serotonin transmission and that serotonin produces these effects at least in part via actions at serotonin 5-HT_2A receptors.     

Assembly and interactions of cotJ-encoded proteins, constituents of the inner layers of the Bacillus subtilis spore coat

During Bacillus subtilis endospore formation, a complex protein coat is assembled around the maturing spore. The coat is made up of more than two dozen proteins that form an outer layer, which provides chemical resistance, and an inner layer, which may play a role in the activation of germination. A third, amorphous layer of the coat occupies the space between the inner coat and the cortex, and is referred to as the undercoat. Although several coat proteins have been characterized, little is known about their interactions during assembly of the coat. We show here that at least two open reading frames of the cotJ operon ( cotJA and cotJC ) encode spore coat proteins. We suggest that CotJC is a component of the undercoat, since we found that its assembly onto the forespore is not prevented by mutations that block both inner and outer coat assembly, and because CotJC is more accessible to antibody staining in spores lacking both of these coat layers. Assembly of CotJC into the coat is dependent upon expression of cotJA . Conversely, CotJA is not detected in the coats of a cotJC insertional mutant. Co-immunoprecipitation was used to demonstrate the formation of complexes containing CotJA and CotJC 6 h after the onset of sporulation. Experiments with the yeast two-hybrid system indicate that CotJC may interact with itself and with CotJA. We suggest that interaction of CotJA with CotJC is required for the assembly of both CotJA and CotJC into the spore coat.     

Induction of alternative oxidase synthesis by herbicides inhibiting branched-chain amino acid synthesis

Sycamore suspension cells ( Acer pseudoplatanus L.) were incubated in the presence of sulfonylurea and imidazolinone herbicides. These inhibitors of acetolactate synthase (ALS), a key enzyme of branched-chain amino acid synthesis, triggered a dramatic induction of the alternative oxidase (AOX). AOX activity increased in treated cells, eventually exceeding cytochrome (cyt) pathway activity. This induction of AOX activity was correlated with the accumulation of a 35 kDa AOX protein in isolated mitochondria, detected by Western blotting with a monoclonal antibody against Sauromatum guttatum AOX. It was preceded by the accumulation of putative 1.6 kb AOX mRNA, detected using an Aox cDNA probe from soybean. The metabolic perturbations induced by the herbicides rather than the herbicide molecules themselves were responsible for this induction of AOX. However, α-oxobutyrate (one of the substrates of ALS) and its transamination product, α-aminobutyrate, which accumulated after herbicide treatment, were not involved. The inhibition of branched-chain amino acid synthesis was probably somehow responsible for the AOX induction since: (i) a mixture of those amino acids (leucine, isoleucine, valine) prevented AOX induction by ALS inhibitors; (ii) the herbicide Hoe 704, a potent inhibitor of acetolactate reducto-isomerase (the enzyme following ALS in the branched-chain amino acid pathway), also triggered AOX induction.     

Fluorescence in situ hybridisation studies provide evidence for somatic mosaicism in de novo dystrophin gene deletions

The fluorescence in situ hybridisation (FISH) technique was tested for its ability to detect somatic mosaicism in mothers of isolated deletion cases of Duchenne/ Becker muscular dystrophy. A control female with known germline and somatic mosaicism was examined, and both the normal cell line and the carrier cell line were detected. Subsequent FISH analysis of three other mothers of boys with apparent de novo dystrophin gene deletions revealed a second patient with a high level of somatic mosaicism, suggesting that a proportion of de novo dystrophin gene deletions occur as mitotic errors early in development rather than as meiotic errors during gametogenesis.