Prevalence of sexually transmitted infections including HIV in street-connected adolescents in western Kenya.

PURPOSE: The objectives of this study were to characterise the sexual health of street-connected adolescents in Eldoret, Kenya, analyse gender disparity of risks, estimate the prevalence of sexually transmitted infections (STIs), and identify factors associated with STIs. METHODS: A cross-sectional study of street-connected adolescents ages 12-21 years was conducted in Eldoret, Kenya. Participants were interviewed and screened for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, herpes simplex virus-2, syphilis and HIV. Descriptive statistics and logistic regression were used to identify factors associated with having any STI. RESULTS: Of the 200 participants, 81 (41%) were female. 70.4% of females and 60.5% of males reported sexual activity. Of those that participated in at least one STI test, 28% (55/194) had ≥1 positive test, including 56% of females; 14% (28/194) had >1 positive test. Twelve females and zero males (6% overall, 14.8% of females) were HIV positive. Among females, those with HIV infection more frequently reported transactional sex (66.7% vs. 26.1%, p=0.01), drug use (91.7% vs. 56.5%, p=0.02), and reported a prior STI (50.0% vs. 14.7%, p<0.01). Having an adult caregiver was less likely among those with HIV infection (33.3% vs. 71.0%, p=0.04). Transactional sex (AOR 3.02, 95% CI (1.05 to 8.73)), a previous STI (AOR 3.46 95% CI (1.05 to 11.46)) and ≥2 sexual partners (AOR 5.62 95% (1.67 to 18.87)) were associated with having any STI. CONCLUSIONS: Street-connected adolescents in Eldoret, Kenya are engaged in high-risk sexual behaviours and females in particular have a substantial burden of STIs and HIV. There is a need for STI interventions targeted to street-connected youth.

Evaluation of longitudinal clinical outcomes and adherence to care among HIV-infected refugees.

BACKGROUND: HIV-infected refugees resettled in the United States face many challenges. Longitudinal data regarding HIV-specific outcomes in this population are limited. METHODS: We reviewed charts of 51 HIV-infected sub-Saharan African refugees matched to 102 nonrefugees. Outcomes analyzed included CD4 counts, viral loads (VLs), antiretroviral treatment (ART) use, appointment adherence, opportunistic infections, and resistance mutations. RESULTS: The ART initiation was similar. Appointment adherence was similar in year 1, but refugees were significantly less adherent beyond year 3. Refugees and nonrefugees spent similar amounts of time in care suppressed (83% vs 80%, P = .93). Refugees had higher odds of viremia following undetectable VL (OR 2.3, P < .05). DISCUSSION: Initially, sub-Saharan African HIV-infected refugees have comparable appointment adherence, ART use, and VL suppression to nonrefugees. Overtime refugees were less adherent to appointments and more likely to have postsuppression viremia. The support services provided to refugees early in care may be important for retention in care and treatment success.

Evidence that the adaptation region of the aspartate receptor is a dynamic four-helix bundle: cysteine and disulfide scanning studies.

The aspartate receptor is one of the ligand-specific, homodimeric chemoreceptors that detects extracellular attractants and triggers the chemotaxis pathway of Escherichia coli and Salmonella typhimurium. This receptor regulates the activity of the histidine kinase CheA, which forms a kinetically stable complex with the receptor cytoplasmic domain. An atomic four-helix bundle model has been constructed for this domain, which is functionally subdivided into the signaling and adaptation subdomains. The proposed four-helix bundle structure of the signaling subdomain, which binds CheA, is fully supported by experimental evidence. Much less evidence is available to test the four-helix bundle model of the adaptation subdomain, which possesses covalent adaptation sites and docking surfaces for adaptation enzymes. The present study focuses on a putative helix near the C terminus of the adaptation subdomain. To probe the structural and functional features of positions G467-A494 in this C-terminal region, a cysteine and disulfide scanning approach has been employed. Measurement of the chemical reactivities of scanned cysteines reveals an alpha-helical periodicity of exposed and buried residues, confirming alpha-helical secondary structure and mapping out a buried packing face. The effects of cysteine substitutions on activity in vivo and in vitro highlight the functional importance of the helix, especially its buried face. A scan for disulfide bond formation between symmetric pairs of engineered cysteines reveals promiscuous collisions between subunits, indicating the presence of significant thermal dynamics. A scan for functional disulfides reveals lock-on and signal-retaining disulfide bonds formed between symmetric pairs of cysteines at buried positions, indicating that the buried face of the helix lies near the subunit interface of the homodimer in the equilibrium structures of both the apo and aspartate-bound states where it plays a critical role in kinase regulation. These results strongly support the existing four-helix bundle model of the adaptation subdomain structure. A mechanistic model is proposed in which a signal is transmitted through the adaptation subdomain by a change in supercoiling of the four-helix bundle.

Extracellular signal-regulated kinase transmits palytoxin-stimulated signals leading to altered gene expression in mouse keratinocytes.

We have been probing the molecular mechanisms of tumor promoters that stimulate distinct initial signals to define critical downstream biochemical events in carcinogenesis. The action of the novel skin tumor promoter palytoxin on signaling and gene expression in keratinocytes, the primary target cells of tumor promoters, was therefore investigated. Palytoxin stimulated an increase in mRNA for matrix metalloproteinase-13 (MMP-13), an enzyme implicated in carcinogenesis, in a keratinocyte cell line derived from initiated mouse skin (308). Palytoxin stimulated an increase in c-Fos binding to the activator protein-1 (AP-1) site present in the promoter of the mouse MMP-13 gene. This effect was specific because palytoxin had little effect on c-Jun, JunB, JunD, FosB, Fra-1, or Fra-2 binding or on overall levels of transcription factor binding. The increase in c-Fos binding corresponded to a palytoxin-stimulated increase in c-Fos protein levels. Palytoxin stimulated the activation of the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase, and p38. The MAPK kinase inhibitor PD 98059 blocked palytoxin-stimulated ERK activation. PD 98059 also blocked the palytoxin-stimulated increases in c-Fos protein levels, c-Fos binding to the AP-1 site, and MMP-13 mRNA. These studies identify important differences between palytoxin-stimulated signaling in keratinocytes derived from initiated mouse skin, the biologically relevant cell type, and other cell lines. Specifically, our data suggest that, in keratinocytes derived from initiated mouse skin, ERK plays an important role in transmitting palytoxin-stimulated signals to three downstream targets that are likely to affect carcinogenesis: c-Fos, AP-1, and MMP-13.

Tumor promoter-induced MMP-13 gene expression in a model of initiated epidermis.

In mouse epidermis in vivo, the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) increases gene expression of matrix metalloproteinase-13 (MMP-13), an enzyme implicated in carcinogenesis. Here we used a keratinocyte cell line (308) derived from initiated mouse skin to investigate TPA-induced MMP-13 gene expression. Use of a pharmacological inhibitor (U0126) demonstrated that extracellular signal regulated kinase (ERK) plays a major role in TPA-induced MMP-13 gene expression. The 5'-flanking sequences of the MMP-13 gene contain binding sites for activator protein-1 (AP-1) and Runx. Both transcription factor families can be modulated by ERK and have been implicated in MMP-13 gene expression. TPA stimulated ERK-dependent increases in c-Fos protein and the c-Fos content of AP-1 complexes. MMP-13 promoter studies indicated that TPA requires AP-1, but not Runx, to induce MMP-13 gene expression. These studies show that in mouse keratinocytes MMP-13 gene expression can be induced through a Runx-independent pathway that involves the ERK-dependent modulation of AP-1.