Pediculosis in a school population.

This nonexperimental, retrospective study of elementary, middle school, and high school children (a) determined the prevalence of pediculosis, (b) identified populations susceptible to head lice infestation, and (c) examined the role of the school nurse in pediculosis management. The findings showed the highest prevalence of pediculosis was among younger school-age children, and girls were 3 times more likely to be infested than boys. Hispanic children had the highest rate of infestation, followed by Caucasian children. African American children showed a 15% infestation rate, a finding not supported by other studies. The role of the school nurse in pediculosis management was restricted by time and budgetary constraints. Findings of this study support the need for a standardized data collection system for pediculosis in all school districts.

Anti-human immunodeficiency virus 1 (HIV-1) activities of 3-deazaadenosine analogs: increased potency against 3'-azido-3'-deoxythymidine-resistant HIV-1 strains.

3-Deazaadenosine (DZA), 3-deaza-(+/-)-aristeromycin (DZAri), and 3-deazaneplanocin A (DZNep) are powerful modulators of cellular processes. When tested against H9 cells infected acutely with two different strains of human immunodeficiency virus 1 (HIV-1) and in the chronically infected monocytoid cell lines U1 and THP-1, the 3-deazanucleosides caused a marked reduction in p24 antigen production. Similar reductions in p24 antigen were seen in phytohemagglutinin-stimulated peripheral blood mononuclear cells infected with clinical HIV-1 isolates. Strikingly, in comparing the therapeutic indices between the paired pre- and post-3'-azido-3'-deoxythymidine (AZT) treatment HIV-1 isolates, DZNep and neplanocin A showed an increase of 3- to 18-fold in their potency against AZT-resistant HIV-1 isolates. In H9 cells treated with DZNep and DZAri, the formation of triphosphate nucleotides of DZNep and DZAri was observed. The mode of action of DZNep and DZAri appears complex, at least in part, at the level of infectivity as shown by decreases in syncytia formation in HIV-1-infected H9 cells and at the level of transcription as both drugs inhibited the expression of basal or tat-induced HIV-1 long terminal repeat chloramphenicol acetyltransferase activity in stably transfected cell lines. Since DZNep induced in H9 cells a rapid expression of nuclear binding factors that recognize the AP-1 transcription site, the anti-HIV-1 activity of the DZA analogs could partly be the induction of critical factors in the host cells. Thus, the 3-deazanucleoside drugs belong to an unusual class of anti-HIV-1 drugs, which may have therapeutic potential, in particular against AZT-resistant strains.

Induction of Apoptosis and c-myc in L1210 Lymphocytic Leukemia Cells by Adenosine.

High concentrations of adenosine (Ado), when added to L1210 lymphocytic leukemia cells, resulted in apoptosis or programmed cell death. The apoptotic process was accompanied by distinct morphological changes including chromatin condensation and blebbing of plasma membranes. Extensive DNA fragmentation was correlated with Ado concentrations. Furthermore, apoptosis in these cells was preceded by an early but transient expression of c-myc proto-oncogene, and was not influenced by homocysteine thiolactone added to the cells. Since severe combined immunodeficiency (SCID) is associated with a deficiency of adenosine deaminase, leading to defects in both cellular and humoral immunity, Ado-induced apoptosis may thus be a contributing factor in the pathology of SCID. Copyright 1994 S. Karger AG, Basel

Long-term retention of 210Pb in man: a unique case of internal contamination.

Knowledge of the long-term effective half-life of 210Pb in man is essential for estimating the cumulative exposure to inhaled short-lived radon daughters from measured values of the 210Pb skeletal burden. For this purpose, the effective half-life has been obtained from sequential measurements of 210Pb made in vivo during a 10-y period and by bioassay of 210Pb excreted in the urine of an individual with a 43-y-old body burden. The long-term effective half-lives obtained by these two methods were 18.1 +/- 4.8 y and 15.8 +/- 0.8 y, respectively. These values are not very different from the estimate of 12.3 y previously adopted by the ICRP.