HIV testing, perceived vulnerability and correlates of HIV sexual risk behaviours of Latino and African American young male gang members.

This study examined HIV testing behaviours, perceived vulnerability to HIV and correlates of sexual risk behaviours of young adult Latino and African American male gang members in Los Angeles, California. Data were collected from 249 gang members aged 18-26 years. The majority (59%) of gang members reported unprotected vaginal intercourse (UVI) in the past 12 months. Only one-third (33.2%) of gang members had ever been tested for HIV. In our multivariate analysis, gang members who reported UVI were more likely to have engaged in the following behaviours: had sex with someone they just met (adjusted odds ratio [AOR] = 4.51), had sex with someone they think or know had a sexually transmitted infection (STI; AOR = 4.67) or had sex while incarcerated (AOR = 8.92). In addition, gang members with a higher perceived vulnerability to HIV were less likely to report UVI in the previous 12 months (AOR = 0.75). These findings offer implications for development of an HIV prevention intervention for young Latino and African American male gang members.

Akt/mTOR pathway is a crucial regulator of skeletal muscle hypertrophy and can prevent muscle atrophy in vivo.

Skeletal muscles adapt to changes in their workload by regulating fibre size by unknown mechanisms. The roles of two signalling pathways implicated in muscle hypertrophy on the basis of findings in vitro, Akt/mTOR (mammalian target of rapamycin) and calcineurin/NFAT (nuclear factor of activated T cells), were investigated in several models of skeletal muscle hypertrophy and atrophy in vivo. The Akt/mTOR pathway was upregulated during hypertrophy and downregulated during muscle atrophy. Furthermore, rapamycin, a selective blocker of mTOR, blocked hypertrophy in all models tested, without causing atrophy in control muscles. In contrast, the calcineurin pathway was not activated during hypertrophy in vivo, and inhibitors of calcineurin, cyclosporin A and FK506 did not blunt hypertrophy. Finally, genetic activation of the Akt/mTOR pathway was sufficient to cause hypertrophy and prevent atrophy in vivo, whereas genetic blockade of this pathway blocked hypertrophy in vivo. We conclude that the activation of the Akt/mTOR pathway and its downstream targets, p70S6K and PHAS-1/4E-BP1, is requisitely involved in regulating skeletal muscle fibre size, and that activation of the Akt/mTOR pathway can oppose muscle atrophy induced by disuse.

Effects of 2-deoxy-D-glucose on methamphetamine-induced dopamine and serotonin neurotoxicity.

The mechanisms underlying the neurotoxic actions of methamphetamine (METH) and related substituted amphetamines are unknown. Previous studies with 2-deoxyglucose (2-DG) have suggested that METH-induced neurotoxicity may involve exhaustion of intracellular energy stores. However, because 2-DG also produces hypothermic effects, and because METH's neurotoxic actions are highly susceptible to thermoregulatory influence, previous findings with 2-DG are difficult to interpret. The present studies were undertaken to further examine the influence of 2-DG's glucoprivic and thermic effects in the context of METH-induced dopamine (DA) and serotonin (5-HT) neurotoxicity. 2-DG protected against METH-induced DA neurotoxicity in both rats and mice. In both species, 2-DG, alone or in combination with METH, produced hypothermic effects. METH's toxic effects on brain 5-HT neurons were either unaffected or exacerbated by 2-DG, depending on species, brain region, and dose of METH tested. These results indicate that different mechanisms may underlie METH-induced DA and 5-HT neurotoxicity, and suggest that, as compared with 5-HT neurons, DA neurons are more susceptible to temperature influence, whereas 5-HT neurons are more vulnerable than DA neurons to metabolic compromise. Additional studies are needed to further assess the role of energy stores in the neurotoxic effects of METH and related drugs.

Isolation and characterization of flagellar preparations from Pseudomonas species.

Sodium dodecyl sulfate-polyacrylamide gel electrophoresis has been used previously to characterize the flagellin of Pseudomonas aeruginosa. flFlagella from several other clinically important species of pseudomonads have been characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their molecular weights have been found to vary among species as follows: P. maltophilia B69 Fla, 33,000; P. stutzeri HEW, 55,000; P. aeruginosa M-2, 53,000. The flagella of P. cepacia strains were divided into two groups based on molecular weight. Type I had a molecular weight of 31,000. The molecular weight of type II was in the range of 44,000 to 46,000. Serologically, type I is a homologous group, whereas type II is a heterologous group. The two flagellin types of P. cepacia appear to be analogous to the two major flagellin types of P. aeruginosa. Characterization of P. cepacia strains by flagellin types may serve as a molecular epidemiological tool.

Virulence of different Pseudomonas species in a burned mouse model: tissue colonization by Pseudomonas cepacia.

The virulence of Pseudomonas aeruginosa and other pseudomonads was examined in a burned mouse model. P. aeruginosa M-2 was highly virulent causing 100% mortality by 38 h with an injection of 10(2) CFU by either a subcutaneous or intraperitoneal route. Subcutaneous injection of 10(2) CFU revealed rapid multiplication of the bacteria at the burn wound with 10(8) CFU/g detectable in the burned skin by 28 h postinjection, 10(5) CFU/g of liver, and 10(3) CFU/ml of blood. Non-P. aeruginosa clinical isolates were markedly less virulent; an injection of greater than or equal to 10(7) CFU caused less than or equal to 60% lethality. P. cepacia SMH colonized the burned skin of thermally injured mice, persisting at levels of 10(7) to 10(8) CFU/g of burned skin after an initial injection of 10(5) CFU. P. cepacia persisted in the burn wound for at least 3 weeks. No organ invasion was detectable throughout this period. Studies with an additional clinical isolate of P. cepacia yielded similar results. An injection of a 10(2) CFU dose revealed that the level of persistence is dose dependent. Results suggest that the tenacious persistence of P. cepacia in the burn wound may provide a model for the study of persistent colonization and infection in a compromised host.