Impact of pyrethroid-impregnated curtains on Phlebotomus papatasi sandflies indoors at Khartoum, Sudan

Laboratory and field investigations were made in an endemic focus of cutaneous leishmaniasis in Khartoum State, Sudan, to evaluate the effects of permethrin-impregnated curtains on the human-biting activity, nocturnal activity and resting behaviour of the vector sandfly Phlebotomus papatasi (Diptera: Psychodidae) indoors. Laboratory bioassays showed that curtains impregnated with 0.5, 1.0 or 1.5 g/m2 permethrin all gave 100% mortality within 24h of exposure of P. papatasi for 3 min. Under natural field conditions, the biting activity indoors and the resting density of P. papatasi were significantly reduced (P<0.001 and P=0.036, respectively) in rooms provided with permethrin-impregnated curtains as compared to control rooms left without curtains or fitted with unimpregnated curtains. No significant difference was found between the numbers of nocturnally active P. papatasi collected in rooms provided with impregnated curtains and rooms left without curtains or provided with unimpregnated curtains (P=0.377). Evidently P. papatasi was not repelled by these doses of permethrin on curtains, but the survival rate of sandflies collected from test rooms provided with permethrin-impregnated curtains was significantly reduced (P=0.036). We conclude that use of permethrin-impregnated curtains may provide a good control method for P. papatasi and other endophilic and/or endophagic sandfly vectors of leishmaniasis.     

Modelling nicotine intake in smokers and snuff users using biological fluid nicotine metabolites

Data from two clinical studies involving smokers and snuff users were analysed to address the estimation of nicotine intake using urinary and salivary nicotine metabolites. Comprehensive regression modelling is performed to determine which combinations of urinary nicotine metabolites provide better estimation of nicotine intake in these subjects than the predominant practice of basing nicotine intake on urinary cotinine analysis alone. Within-subject and between-subject variability is examined with regard to reliability of measurement and replicate sampling. Salivary cotinine models are compared to urinary metabolite models. Results suggest that estimation of nicotine intake is greatly improved by measuring urinary cotinine and additional metabolites (trans-3´-hydroxycotinine, and glucuronide conjugates) rather than measuring only cotinine. Analyses also indicate that replicate sampling on subjects greatly improves the reliability of the measurement. Based on these data, a model to predict nicotine equivalents based solely on saliva cotinine was severely inferior to any of the urinary models, including that of urinary cotinine alone.     

The Role of Grandmothers in the Lives of Preschoolers Growing Up in Urban Poverty

Abstract

Little is known about how grandmothers may influence children's development, although they may frequently assist parents in the raising of their children, especially among low-income families. Data from Welfare, Children, and Families: A Three-City Study were used to explore how preschoolers function academically and psychologically over time based on grandmothers' residential status and level of caretaking responsibility. Longitudinal regression analyses suggest that children who consistently have custodial grandmothers lag behind their peers in the development of their academic achievement, whereas those in multigenerational households consistently have more socioemotional problems over time. However, many of these differences are accounted for by co-occurring family characteristics. Furthermore, children transitioning into the care of custodial grandmothers were found to have positive changes in self-regulation and socioemotional functioning, and those transitioning into multigenerational households had more problems with self-regulation over time.     

Analysis of Plankton Dynamics in a Southwestern U.S.A. Reservoir Using ATP Assays

Plankton biomass in size segregated (i.e. 0.45–10 μm, 10–64 μm, 64–165 μm, and > 165 μm) samples was measured using ATP assays for two years in H. H. Moss Reservoir. The presence of variable numbers of microcrustacean zooplankton in the > 165 μ size class introduced significant, and perhaps inaccurate, variance into temporal dynamics of total ATP concentrations. As many as six physiochemical parameters, measured during 1975–76, were required to produce a significant multiple regression against ATP concentrations; a significant correlation between total ATP measured in the photic zone and surface temperature was observed. A large standing crop of nannoplankton (i.e. 0.45–10 μm) existed in the anaerobic and aphotic hypolimnion during summer stratification both years. This suggested that microbial heterotrophy was an especially important primary trophic event in the reservoir. Particulate (POC) and dissolved (DOC) organic carbon were measured in 1976–77. Organic carbon (POC + DOC) regressed significantly against ATP concentration in the 0.45–10 μm size class and microbial biomass (i.e. 0.45–165 μm) averaged 32 per cent of POC. When biomass was monitored over 24-hour periods in the photic zone, significant changes were documented in various size classes, especially nannoplankton; but total microbial biomass remained relatively constant.     

Circumvention of defective CD4 T helper cell function in HIV-infected individuals by stimulation with HLA alloantigens

PBL from approximately 50% of asymptomatic individuals infected with HIV have been previously demonstrated to exhibit defective in vitro Th function that is selective for influenza A virus (FLU), but not for HLA alloantigens (ALLO). In this report, we have further studied HIV+ individuals with this selective Th defect, and demonstrate that defective in vitro CTL responses to FLU can be restored by costimulation with FLU + ALLO. In contrast, HIV+ patients who have lost Th responses to ALLO were unable to correct CTL responses to FLU by this costimulation procedure. These findings indicate that intact Th responses to ALLO can be used in vitro to provide Th signals necessary to activate the T effector cell response to a potential pathogenic virus. Our results raise the possibility that a program of in vivo coimmunization with ALLO plus antigens of potential pathogens (including HIV) can be useful in HIV+ patients exhibiting selective defects in Th function. Furthermore, this approach could be incorporated in vaccine trials aimed at enhancing immunity to HIV in patients who have been infected previously with this virus.