Human seminal plasma inhibits brain nitric oxide synthase activity

Nitric oxide is a chemical messenger which functions as a neurotransmitter or as a cytotoxic agent. Nitric oxide synthase (NOS) has been isolated from various mammalian reproductive tissues* The presence or absence of NOS in spermatozoa has not yet been reported. We therefore tested human and marine spermatozoa for NOS activity by measuring the conversion of argmine to citmlline. No activity was found either in human or in murine spermatozoa. Human native semen and human seminal plasma exerted an inhibition on brain NOS activity, as assayed on rat brain cytosolic fractions. This inhibitory effect was dependent on the amount of protein present in the human seminal plasma. No inhibitory effect was observed when homogenates of washed spermatozoa were tested. The human seminal plasma did not affect the Michaelis constant (Km) of NOS for L-arginine (endogenous NOS substrate) whereas the maximal velocity (Vmax) was reduced, suggesting that it contains a non-competitive inhibitor of brain NOS. This inhibitory component was virtually insensitive to heat; a 10 min treatment to 95°C only slightly reduced its ability to inhibit brain NOS. The physiological relevance of our observations remains to be elucidated. Human seminal plasma may exert an inhibition of nitric oxide synthesis on cells other than spermatozoa or on cells from the male or female genital tract, modulating directly or indirectly (via modulation of reactive oxygen species formation) the functional state of the spermatozo

High prevalence of HIV, HBsAg and anti-HCV positivity among people who injected drugs : results of the first bio-behavioral survey using respondent-driven sampling in two urban areas in Mozambique

Background Few countries in sub-Saharan Africa know the magnitude of their HIV epidemic among people who inject drugs (PWID). This was the first study in Mozambique to measure prevalence of HIV, HBV, and HCV, and to assess demographic characteristics and risk behaviors in this key population. Methods We used respondent-driven sampling (RDS) to conduct a cross-sectional behavioral surveillance survey of PWID in two cities of Mozambique lasting six months. Participants were persons who had ever injected drugs without a prescription. Participants completed a behavioral questionnaire and provided blood specimens for HIV, hepatitis B surface antigen (HBsAg) and hepatitis C virus antibody (anti-HCV) testing. We performed RDS-adjusted analysis in R 3.2 using RDSAT 7.1 weights. Results We enrolled 353 PWID in Maputo and 139 in Nampula/Nacala; approximately 95% of participants were men. Disease prevalence in Maputo and Nampula/Nacala, respectively, was 50.1 and 19.9% for HIV, 32.1 and 36.4% for HBsAg positivity, and 44.6 and 7.0% for anti-HCV positivity. Additionally, 8% (Maputo) and 28.6% (Nampula/Nacala) of PWID reported having a genital sore or ulcer in the 12 months preceding the survey. Among PWID who injected drugs in the last month, 50.3% (Maputo) and 49.6% (Nampula/Nacala) shared a needle at least once that month. Condomless sex in the last 12 months was reported by 52.4% of PWID in Maputo and 29.1% in Nampula/Nacala. Among PWID, 31.6% (Maputo) and 41.0% (Nampula/Nacala) had never tested for HIV. In multivariable analysis, PWID who used heroin had 4.3 (Maputo; 95% confidence interval [CI]: 1.2, 18.2) and 2.3 (Nampula/Nacala; 95% CI: 1.2, 4.9) greater odds of having HIV. Conclusion Unsafe sexual behaviors and injection practices are frequent among PWID in Mozambique, and likely contribute to the disproportionate burden of disease we found. Intensified efforts in prevention, care, and treatment specific for PWID have the potential to limit disease transmission

Formation of Complexes at Plasmodesmata for Potyvirus Intercellular Movement Is Mediated by the Viral Protein P3N-PIPO

Intercellular transport of viruses through cytoplasmic connections, termed plasmodesmata (PD), is essential for systemic infection in plants by viruses. Previous genetic and ultrastructural data revealed that the potyvirus cyclindrical inclusion (CI) protein is directly involved in cell-to-cell movement, likely through the formation of conical structures anchored to and extended through PD. In this study, we demonstrate that plasmodesmatal localization of CI in N. benthamiana leaf cells is modulated by the recently discovered potyviral protein, P3N-PIPO, in a CI:P3N-PIPO ratio-dependent manner. We show that P3N-PIPO is a PD-located protein that physically interacts with CI in planta. The early secretory pathway, rather than the actomyosin motility system, is required for the delivery of P3N-PIPO and CI to PD. Moreover, CI mutations that disrupt virus cell-to-cell movement compromise PD-localization capacity. These data suggest that the CI and P3N-PIPO complex coordinates the formation of PD-associated structures that facilitate the intercellular movement of potyviruses in infected plants