The effect of AZT on in vitro lymphokine-activated killer (LAK) activity in human immunodeficiency virus type-1 (HIV-1) infected individuals

Human immunodeficiency virus type-1 (HIV-1)-infected individuals exhibit functional impairment in various forms of cell-mediated cytotoxicities (CMC) at all stages of disease. The purpose of this study was to determine (i) if peripheral blood mononuclear cells (PBMC) obtained from HIV-1-infected patients could be stimulated in vitro to yield lymphokine-activated killer (LAK) activity; (ii) if non-MHC-restricted gp120-specific CMC could be preserved; and (iii) what effect zidovudine (AZT) would have on LAK activity. Fourteen asymptomatic HIV-1 seropositive adults and five healthy seronegative adults (controls) were evaluated. PBMCs were isolated and incubated in media or supplemented with IL-2 for 4 or 72 hr. Lysis of the NK resistant target cell line, Daudi, was similar for the control and experimental group. The increase in activity after stimulation was elevated to a similar degree in both seronegative and seropositive groups (P less than 0.001). LAK activity was significantly decreased (P = 0.011) when AZT was added to LAK cultures. In addition, virus production may not have been completely inhibited by AZT in LAK cultures. Thus, PBMCs from asymptomatic HIV-1-infected patients could be stimulated to yield LAK activity. However, AZT can impair LAK generation. It is unclear if LAK activation results in virus production that cannot be inhibited by AZT in this system. Further definition in other patient populations is required prior to applying this information to clinical trials.     

Early gene interaction during prepupal expression of Drosophila arginine kinase

Arginine kinase displays a distinctive rise and fall in specific activity and specific protein levels during the prepupal stage of Drosophila development with maximal activity occurring at morphological stage P3. This developmentally regulated peak is under the influence of ecdysone. Altered doses of the major ecdysone-inducible “early” genes at cytological regions 75B and 2B5 alter this pattern of expression while altered doses of another major “early” gene at 74EF have no effect. We hypothesize that a product of the 2B5 locus and a product of the 75B locus interact to effect this developmental pattern of expression of Drosophila arginine kinase. © 1992 Wiley-Liss, Inc.     

L-arabinose metabolism in Azospirillum brasiliense

An oxidative pathway by which L-arabinose is converted to alpha-ketoglutarate in crude extracts of Azospirillum brasiliense is demonstrated. Specific activities of enzymes involved in the pathway were determined, and several pathway intermediates were identified.     

Intracellular phosphate pools show compartmentalization of intracellular pH in turtle urinary bladder

The urinary bladder of the fresh water turtle is capable of acidification and Na transport, in vitro, and it has been extensively used as a model of distal nephron of the kidney. In the course of measuring intracellular pH of stripped turtle bladder mucosa with phosphorus nuclear magnetic resonance, we observed the consistent presence of two inorganic phosphorus resonances under aerobic conditions, indicating the existence of a pH gradient possibly between cytosol and mitochondrion. This pH gradient was collapsed by addition of N₂ and could be restored by reintroduction of oxygen. These observations demonstrate the existence of a spontaneous pH gradient between cytosol and mitochondria of turtle bladder epithelial cells.     

Fast atom bombardment: A new mass spectrometric method for peptide sequence analysis

We have studied a selection of peptides using a new mass spectrometric ionisation technique - fast atom bombardment (FAB). We define the fragmentation pathways observed and comment on the utility in sequence analysis. A simple acetylation experiment is shown to aid rapid sequence assignment.     

Purification of glutamine synthetase from a variety of bacteria

We have developed two procedures which allow the very rapid purification of glutamine synthetase (GS) from a diverse variety of bacteria. The first procedure, based upon differential sedimentation, depends upon the association of GS with deoxyribonucleic acid in cell extracts. The second procedure, derived from the method of C. Gross et al (J. Bacteriol. 128:382-389, 1976) for purifying ribonucleic acid polymerase by polyethylene glycol (PEG) precipitation, enabled us to obtain high yields of GS from either small or large quantities of cells. We used the PEG procedure to purify GS from Klebsiella aerogenes, K. pneumoniae, Escherichia coli, Salmonella typhimurium, Rhizobium sp. strain 32H1, R. meliloti, Azotobacter vinelandii, Pseudomonas putida, Caulobacter crescentus, and Rhodopseudomonas capsulata. The purity of the GS obtained, judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was high, and in many instances only a single protein band was detected.