In-utero infection with HIV-1 associated with suppressed lymphoproliferative responses at birth

In-utero exposure to HIV-1 may affect the immune system of the developing child and may induce HIV-1-specific immune responses, even in the absence of HIV-1 infection. We evaluated lymphoproliferative capacity at birth among 40 HIV-1-uninfected infants born to HIV-1-infected mothers and 10 infants who had acquired HIV-1 in utero. Cord blood mononuclear cells were assayed using [(3) H]-thymidine incorporation for proliferation in response to HIV-1 p55-gag and the control stimuli phytohaemagglutinin (PHA), Staphylococcus enterotoxin B (SEB) and allogeneic cells. In response to HIV-1 p55-gag, eight (20%) HIV-1-exposed, uninfected (EU) infants had a stimulation index (SI) ≥ 2 and three (30%) in-utero HIV-1 infected infants had SI ≥2. The frequency and magnitude of responses to HIV-1 p55-gag were low overall, and did not differ statistically between groups. However, proliferative responses to control stimuli were significantly higher in EU infants than in infants infected in utero, with a median SI in response to PHA of 123 [interquartile range (IQR) 77-231] versus 18 (IQR 4-86) between EU and infected infants, respectively (P < 0·001). Among infected infants, gestational maturity was associated with the strength of HIV-1 p55-gag response (P < 0·001); neither maternal nor infant HIV-1 viral load was associated. In summary, EU and HIV-1-infected infants mounted HIV-1-specific lymphoproliferative responses at similar rates (20-30%), and although global immune function was preserved among EU infants, neonatal immune responses were significantly compromised by HIV-1 infection. Such early lymphoproliferative compromise may, in part, explain rapid progression to AIDS and death among HIV-1-infected infants.

Elimination rate constants of 46 polycyclic aromatic hydrocarbons in the unionid mussel, Elliptio complanata

Elimination rate constants (k2), biological half-lives (t(1/2)), and the time required to reach 95% of steady-state (t95) are reported for 46 individual polycyclic aromatic hydrocarbons (PAHs) including both parent and alkyl homologues, for the freshwater unionid mussel, Elliptio complanata. Elimination rate constants generally follow first-order kinetics and range from 0.04/day (d) for perylene to 0.26/d for 2,6-dimethylnapthalene, half-lives range from 2.6 to 16.5 d, and t95 values range from 11.3 to 71.3 d. These values compare well with other k2, t(1/2), and t95 values reported in the literature for PAHs and other classes of hydrophobic organic contaminants. A linear regression of k2 versus log Kow demonstrates dependence of PAH elimination on hydrophobicity, as measured by an r2 value of 0.83, and produces the following regression equation: k2 = -0.06 (log Kow) + 0.44. This study provides evidence that mussels experiencing different forms of physiological stress (e.g., handling stress and fungal or bacterial growth) can exhibit large variation in toxicokinetic parameters. These results are particularly relevant to the extrapolation of laboratory results to field situations.