NIDA technical review: nitrite inhalants

Nitrite inhalants are commonly abused substances in the US and Europe. "Nitrite inhalants and AIDS" was a popular topic in the early 1980s when the cause of AIDS was not known. With the discovery of HIV, concern about nitrite use wained. However, nitrite inhalant use is associated with behavioral relapse and HIV transmission among gay men, with decreased lymphocyte counts and natural killer cell activity in laboratory studies, and remains a candidate "cofactor" in the pathogenesis of AIDS-related Karposi sarcoma. Discouraging nitrite use continues to be a worthwhile public health goal. Participants recommend specific research efforts.     

Epitope mapping using histidine-tagged protein fragments: application to Escherichia coli RNA polymerase sigma 70

The pathogenic Neisseria have exploited the processes of horizontal DNA transfer and genetic recombination as mechanisms for the generation of extensive protein variation and modulation of gene expression. Localized recombinations have been well documented in members of multigene families as have alterations in short repetitive sequences. Here we report an analysis of the chromosomal structure of a defined lineage of Neisseria gonorrhoeae strain MSl1 pilin variants. This study reveals the occurrence of large rearrangements, including the amplification of a 26 kb region and an inversion involving more than a third of the chromosome. Additionally, a restriction site polymorphism that correlates with pilin expression has been observed. These findings highlight the flexibility of the gonococcal genome.     

Survival in lung reperfusion injury is improved by an antibody that binds and inhibits L- and E-selectin

The selectins are a three-member family of leukocyte, platelet, and endothelial cell adhesion proteins that mediate leukocyte traffic into normal and inflamed tissues. P-selectin is expressed by endothelial cells and platelets, E-selectin by endothelial cells, and L-selectin by circulating leukocytes. To determine if selectin-mediated leukocyte adhesion influences the development of lung reperfusion injury, we studied hemodynamics and respiratory and inert gas exchange in sheep subjected to 3-hour in situ left lung ischemia followed by 6-hour left lung reperfusion with the right lung excluded. Ten minutes before reperfusion, eight animals received EL-246 (1 mg/kg intravenously), a novel antihuman selectin antibody that recognizes and blocks both L- and E-selectin and cross-reacts in sheep. Eight control animals with ischemia received no treatment, whereas three received an isotype-matched antihuman L-selectin antibody that does not cross-react in sheep (DREG-56, 1 mg/kg intravenously). Eight sham control sheep underwent an identical operative procedure but were never subjected to ischemia. Volume-cycled, pressure-limited (20 cm H2O) mechanical ventilation was consistent in all animals throughout the experiment. Six-hour survival in EL-246 recipients (100%) was significantly higher than in either ischemic control sheep (37.5%) or DREG-56 recipients (33.3%), but gravimetric lung water was equivalent in EL-246 recipients (5.9 +/- 1.7 ml/kg), ischemic control sheep (8.3 +/- 3.0 ml/kg), and DREG-56 recipients (9.1 +/- 2.6 ml/kg).(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of bond strengths of three denture base resins to treated nickel-chromium-beryllium alloy

The success of radiotherapy in eradicating tumours depends on the total radiation dose, but what limits this dose is the tolerance of the normal tissues within the treatment volume. Studies involving fibroblast survival have demonstrated the theoretical feasibility of a predictive assay of radiation sensitivity, but such an assay is still far from clinical application. Using pulsed-field gel electrophoresis (PFGE), we have quantified the initial "apparent" number of DNA double-strand breaks (dsb) induced by the radiation as an alternative measure of sensitivity in 2 different normal cell types from the same patients, epidermal skin cells and lymphocytes. We found significant inter-individual variation in the measured dsb (1-5 dsb/Gy/DNA unit). We also found a linear correlation between molecular damage in lymphocytes and skin samples from the same patient (slope = 0.83; r = 0.694; p = 0.0001). These results suggest that the initial number of dsb could be used as an indicator of the in vivo response to radiation.     

Phosphatidylinositol 3-kinase-gamma activates Bruton's tyrosine kinase in concert with Src family kinases

Bruton's tyrosine kinase (Btk) is essential for normal B lymphocyte development and function. The activity of Btk is partially regulated by transphosphorylation within its kinase domain by Src family kinases at residue Tyr-551 and subsequent autophosphorylation at Tyr-223. Activation correlates with Btk association with cellular membranes. Based on specific loss of function mutations, the Btk pleckstrin homology (PH) domain plays an essential role in this activation process. The Btk PH domain can bind in vitro to several lipid end products of the phosphatidylinositol 3-kinase (PI 3-kinase) family including phosphatidylinositol 3,4,5-trisphosphate. Activation of Btk as monitored by elevation of phosphotyrosine content and a cellular transformation response was dramatically enhanced by coexpressing a weakly activated allele of Src (E378G) and the two subunits of PI 3-kinase-gamma. This activation correlates with new sites of phosphorylation on Btk identified by two-dimensional phosphopeptide mapping. Activation of Btk was dependent on the catalytic activity of all three enzymes and an intact Btk PH domain and Src transphosphorylation site. These combined data define Btk as a downstream target of PI 3-kinase-gamma and Src family kinases.     

UDP-GlcNAc:Ser-protein N-acetylglucosamine-1-phosphotransferase from Dictyostelium discoideum recognizes serine-containing peptides and eukaryotic cysteine proteinases

Phosphoglycosylation catalyzed by UDP-GlcNAc:Ser-protein N-acetylglucosamine-1-phosphotransferase (Ser:GlcNAc phosphotransferase) adds GlcNAcalpha-1-P to peptidyl-Ser of selected Dictyostelium discoideum proteins. Lysosomal cysteine proteinase (CP), proteinase-1(CP7), is the major phosphoglycosylated protein in bacterially grown amoebae. GlcNAc-1-P is added within a Ser-rich domain containing SSS, SGSG, or SGSQ repeated motifs that are not found in other papain-like CPs. We studied the substrate specificity of the transferase using peptides containing these motifs and 12 other peptides with one or more Ser residues. Phosphoglycosylation is comparable for all three Dictyostelium CP motifs, but it is not restricted to them. Flanking residues in the other peptides strongly influence phosphoglycosylation efficiency. Dictyostelium microsomal membranes also phosphoglycosylate endogenous acceptors, and some of these acceptors occur as an 18 S complex with the transferase. CP-serine motif peptides inhibit endogenous acceptor phosphoglycosylation weakly (30-40%) at 800 microM, whereas catalytically inactive proteinase-1(CP7) and other non-phosphoglycosylated eukaryotic CPs, lacking the serine domain, inhibit transferase activity at 1-4 microM. SDS denaturation destroys the inhibitory potential of all CPs showing that transferase recognizes a conformation-dependent feature that is shared by all. Proteinase-1(CP7) expressed in Escherichia coli lacks GlcNAc-1-P, but it is a substrate for Ser:GlcNAc phosphotransferase, Km = 5.6 microM. Thus, Ser:GlcNAc phosphotransferase recognizes both acceptor peptide sequences and a conformational feature of eukaryotic CPs. This may be physiologically important for establishing or maintaining non-overlapping groups of GlcNAc-1-P- and Man-6-P-modified Dictyostelium proteins that reside in functionally distinct endo-lysosomal vesicles.     

Capturing the environment, a metafrontier approach to the drinking water sector

Environmental factors add complexity to the comparison between specific activities or entire entities. Decision making units with an inferior performance are tempted to invoke that their organization is "different" from the others in the data set. By reinterpreting and extending the metafrontier literature, we propose an all-embracing concept to fully capture the operational environment. We suggest the "Group Specific Technical Efficiency" as a new measure to assess the overall efficiency of a utility while allowing for environmental differences. A real-world example of drinking water utilities from five different countries illustrates the concept.