AIDSWEEKLY Plus; Monday, August 27, 2007
Staff Medical Writers

Study 1: A report, "Gp120-mediated cytotoxicity of human brain microvascular endothelial cells is dependent on p38 mitogen-activated protein kinase activation," is newly published data in Journal of NeuroVirology. "Breakdown of the blood-brain barrier has been shown to contribute to neurological disorders that are prevalent in human immunodeficiency virus type 1 (HIV-1)-infected individuals, but the mechanisms involved in HIV-1-associated blood-brain barrier dysfunction remain incompletely understood. Using human brain microvascular endothelial cells (HBMECs) that constitute the blood-brain barrier, the authors determined the cytotoxic effects of gp120 on HBMECs," scientists writing in the Journal of NeuroVirology report.

"The authors showed that gp120 induced cytotoxicity of HBMECs derived from children, which required cotreatment with interferon (IFN)-gamma. IFN-gamma treatment exhibited up-regulation of the chemokine receptors CCR3 and CCR5 in children's HBMECs. In contrast, HBMECs isolated from adults were not responsive to gp120-mediated cytotoxicity. Peptides of gp120 representing binding regions for CD4 and chemokine receptors as well as CD4 antibody inhibited gp120-mediated cytotoxicity of HBMECs. RANTES, as expected, inhibited M-tropic gp120-mediated HBMEC cytotoxicity, whereas stromal cell-derived factor (SDF)-1alpha failed to inhibit T-tropic gp120-mediated cytotoxicity. Of interest, gp120 peptides representing non-CD4/non-chemokine receptor binding regions inhibited gp120-mediated HBMEC cytotoxicity. In addition, the authors showed that gp120-mediated HBMEC cytotoxicity involved p38 mitogen-activated protein kinase pathway," wrote N.A. Khan and colleagues, Johns Hopkins University, Division of Pediatric Infectious Diseases.

The researchers concluded: "Taken together, these findings showed that gp120, in the presence of IFN-gamma, can cause dysfunction of the blood-brain barrier endothelium via MAPK pathways involving several gp120-HBMEC interactions."

Khan and colleagues published their study in the Journal of NeuroVirology (Gp120-mediated cytotoxicity of human brain microvascular endothelial cells is dependent on p38 mitogen-activated protein kinase activation. J Neurovirol. 2007 Jun;13(3):242-51).

Additional information can be obtained by contacting N.A. Khan, Johns Hopkins University School of Medicine, Division of Pediatric Infectious Diseases, Baltimore, Maryland 21287 USA.

Study 2: Women married to injecting drug users in northern Vietnam do not initiate condom use for fear of their partner's reaction.

According to a study from the United States, "This paper elucidates the social context of HIV risk behavior and intracouple risk communication among injecting drug users (IDUs) and their main sex partner.

"Data on shared injection equipment, unprotected sex with multiple partners, unprotected sex with a main partner and couples' dynamics and risk communication were gathered through separate in-depth interviews with 11 active male IDUs and 11 of their primary female sex partners in northern Vietnam."

"The majority of IDUs' sex partners does not inject drugs and is monogamous. In contrast, most IDUs reported a wide range of risky practices including needle sharing and unprotected sex with multiple, often concurrent, sex partners.

"Men rarely used condoms with primary partners. Many IDUs worried about their HIV-status, but none disclosed their injecting or sexual practices to their sex partners, leaving their partners unaware of their HIV risk," reported researchers.

"Among women who worried about HIV/AIDS," continued V.F. Go and colleagues at Johns Hopkins University in Baltimore, "the vast majority was unable to influence their partner's needle sharing or extramarital affairs and most would not initiate condom use because they feared their partner's reaction."

"Couple-based interventions to facilitate risk communication combined with programs to promote condom use among male IDUs, may help to reduce HIV transmission from IDUs to their primary partners," investigators concluded.

Go and colleagues published their study in Drug and Alcohol Dependence (Intracouple communication dynamics of HIV risk behavior among injecting drug users and their sexual partners in northern Vietnam. Drug Alcohol Depend. 2006 Sep 1;84(1):69-76).

For more information, contact V.F. Go, Johns Hopkins University, Bloomberg School Public Health, Dept. of Epidemiology, 615 N Wolfe St., E6610, Baltimore, MD 21205, USA.

Study 3: Demographic and behavioral correlates have been identified for unprotected anal sex with casual partners among men who have sex with men.

"This study identified demographic and behavioral correlates of engaging in unprotected anal sex (UAS) with nonmain partners among men having sex with men (MSM).

"Just over 1,000 men completed anonymous surveys with 25% of the men reporting their most recent sexual act with a nonmain male partner was UAS," wrote investigators in the United States.

According to the authors, "These men tended to be white, older, HIV seropositive, and high (or drunk) when having sex. In multivariate analysis being seropositive, and being high or drunk retained significance."

"Subsequent research may build upon these findings to determine the causal pathway to UAS among MSM having sex with nonmain partners," said D.R. Holtgrave and colleagues at Johns Hopkins University in Baltimore.

"Findings may be useful in constructing prevention interventions for MSM frequenting gay venues," concluded researchers.

Holtgrave and colleagues published their study in AIDS and Behavior (Correlates of unprotected anal sex with casual partners: A study of gay men living in the southern United States. AIDS Behav, 2006;10(5):575-578).

For additional information, contact D.R. Holtgrave, Johns Hopkins University, Dept. of Health Behavioral & Society, Bloomberg School Public Health, 624 N Broadway, Room 280, Baltimore, MD 21212, USA.

Keywords: Baltimore, Maryland, United States, HIV Prevention, Risk Behavior, Men Who Have Sex With Men, HIV/AIDS, Anal Sex. This article was prepared by AIDS Weekly editors from staff and other reports.

Reference

Khan NA, Di Cello F, Stins M, et al., Gp120-mediated cytotoxicity of human brain microvascular endothelial cells is dependent on p38 mitogen-activated protein kinase activation, J Neurovirol. 2007 Jun;13(3):242-51.

Go VF, Quan VM, Voytek C, et al., Intra-couple communication dynamics of HIV risk behavior among injecting drug users and their sexual partners in Northern Vietnam, Drug Alcohol Depend. 2006 Sep 1;84(1):69-76.

Holtgrave DR, Crosby R, Shouse RL, Correlates of unprotected anal sex with casual partners: a study of gay men living in the southern United State, AIDS Behav. 2006 Sep;10(5):575-8..

2007-08-27
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