Bile acid uptake and calcium flux in brush border membrane vesicles

Our laboratory has recently reported that intestinal bile acid malabsorption in cystic fibrosis (CF) is a primary mucosal cell defect. Others have suggested that elevated intracellular Ca⁺⁺ levels in other cell types in CF may represent a common primary dysfunction in Ca⁺⁺ efflux in these cells. We examined the possibility that intestinal bile acid absorption and Ca⁺⁺ efflux in mucosal cells may be linked physiologically. Brush border membrane vesicles (BBMV) prepared from guinea pig ileum served as the experimental model to test this hypothesis. Ca⁺⁺ (2.5×10^?3M) present in the incubation medium did not alter the uptake of taurocholic acid (TCA) by BBMV. Also, TCA uptake into BBMV preloaded with Ca⁺⁺ was not significantly different from that in BBMV not previously loaded with Ca⁺⁺. Furthermore, with TCA present in the incubation medium, Ca⁺⁺ efflux from preloaded BBMV was not altered. These data suggest that ileal TCA uptake, as measured by BBMV, is not dependent upon either intra- or extravesicular Ca⁺⁺. Also, Ca⁺⁺ efflux from BBMV is unaffected by TCA uptake. Although separate lines of evidence suggest that intestinal bile acid malabsorption and reduced plasma membrane Ca⁺⁺ flux are primary defects in CF, we conclude that in the normal intestine these functions are independent physiological processes.     

Assimilation of 13NH 4 + by Anthoceros grown with and without symbiotic Nostoc

The pathways of assimilation of ammonium by pure cultures of symbiont-free Anthoceros punctatus L. and the reconstituted Anthoceros-Nostoc symbiotic association were determined from time-course (5–300 s) and inhibitor experiments using ¹³NH ₄ ⁺ . The major product of assimilation after all incubation times was glutamine, whether the tissues were cultured with excess ammonium or no combined nitrogen. The ¹³N in glutamine was predominantly in the amide-nitrogen position. Formation of glutamine and glutamate by Anthoceros-Nostoc was strongly inhibited by either 1mM methionine sulfoximine (MSX) or 1 mM exogenous ammonium. These data are consistent with the assimilation of ¹³NH ₄ ⁺ and formation of glutamate by the glutamine synthetase (EC 6.3.1.2)-glutamate synthase (EC 1.4.7.1) pathway in dinitrogen-grown Anthoceros-Nostoc. However, in symbiont-free Anthoceros, grown with 2.5 mM ammonium, formation of glutamine, but not glutamate, was decreased by either MSX or exogenous ammonium. These results indicate that during short incubation times ammonium is assimilated in nitrogenreplete Anthoceros by the activities of both glutamine synthetase and glutamate dehydrogenase (EC 1.4.1.2). In-vitro activities of glutamine synthetase were similar in nitrogen-replete Anthoceros and Anthoceros-Nostoc, indicating that the differences in the routes of glutamate formation were not based upon regulation of synthesis of the initial enzyme of the glutamine synthetase-glutamate synthase pathway. When symbiont-free Anthoceros was cultured for 2 d in the absence of combined nitrogen, total ¹³NH ₄ ⁺ assimilation, and glutamine and glutamate formation in the presence of inhibitors, were similar to dinitrogen-grown Anthoceros-Nostoc. The routes of immediate (within 2 min) glutamate formation and ammonium assimilation in Anthoceros were apparently determined by the intracellular levels of ammonium; at low levels the glutamine synthetase-glutamate synthase pathway was predominant, while at high levels independent activities of both glutamine synthetase and glutamate dehydrogenase were expressed.     

Uptake and dissimilation of glycerol by wild type and glycerol nonutilizing strains of Neurospora crassa

Summary Seven mutant strains defective for utilization of glycerol, glyceraldehyde or dihydroxyacetone were isolated. One strain was deficient for NAD-linked glycerol-3-phosphate dehydrogenase, two for glycerol kinase, and four had no detected enzymatic deficiency, although one of the latter strains was deficient in glycerol uptake. Glycerol uptake was increased by incubation in glycerol, glycerol-3-phosphate, erythritol, and propanediol, and was protein-mediated below 0.14 mM glycerol, but at higher concentrations free diffusion predominated. Glycerol uptake was decreased by cycloheximide and was more sensitive to sodium azide than to iodoacetate.     

Cultural Aspects of Health and Illness Behavior in Hospitals

Health care attitudes reflect the basic world view and values of a culture, such as how we relate to nature, other people, time, being, society versus community, children versus elders and independence versus dependence. Illness behavior determines who is vulnerable to illness and who agrees to become a patient—since only about one third of the ill will see a physician. Cultural values determine how one will behave as a patient and what it means to be ill and especially to be a hospital patient. They affect decisions about a patient''s treatment and who makes the decisions. Cultural differences create problems in communication, rapport, physical examination and treatment compliance and follow through. The special meaning of medicines and diet requires particular attention. The perception of physical pain and psychologic distress varies from culture to culture and affects the attitudes and effectiveness of care-givers as much as of patients. Religious beliefs and attitudes about death, which have many cultural variations, are especially relevant to hospital-based treatment. Linguistic and cultural interpreters can be essential; they are more available than realized, though there are pitfalls in their use. Finally, one must recognize that individual characteristics may outweigh the ethnic and that a good caring relationship can compensate for many cultural missteps.     

Simultaneous determination of leu-enkephalin localization and [3H]γ-aminobutyric acid uptake in rat striatal cell cultures

The purpose of this study was to investigate the coexistence of gamma-aminobutyric acid (GABA) and leu-enkephalin in single neurons from the corpus striatum. Monolayer cell cultures, started from newborn rat corpus striatum, were grown in serum-free medium and examined using GABA autoradiography and leu-enkephalin immunocytochemistry in a double-label protocol. Examples of cells were found which were positive for one or the other neurotransmitter or for neither transmitter, but not for both. Furthermore, cells which appear similar by morphological criteria alone differed in transmitter specificity. We conclude that the two transmitters tested are not localized within single cells and that morphology alone is inadequate to identify functional cell classes in this area.     

THE LYMPHOCYTES OF CHRONIC LYMPHOCYTIC LEUKEMIA: THEIR PROLIFERATION AND CELL CYCLE KINETICS

Lymphocytes obtained from CLL patients exhibited a delayed and reduced response to PHA when cultured in diffusion chambers. DNA synthesis (8–10 hr) and general time (15–19 hr) of the late-developing CLL blasts were consistent with normal values ( T _s: 8–10 hr; T _c: 14–17 hr). However, the G₂ period of CLL blasts seemed more variable, and their mitotic index during the response at 5–6 days was 30–50% of the values determined for normal blasts during their peak response at 2–3 days.     

Localization of Parental Deoxyribonucleic Acid from Superinfecting T4 Bacteriophage in Escherichia coli

High-resolution autoradiography has been employed to localize the nonsolubilized but genetically excluded deoxyribonucleic acid (DNA) of T4 bacteriophage superinfecting endonuclease I-deficient Escherichia coli. This DNA was found to be associated with the cell envelope (this term is used here to include all cellular components peripheral to and including the cytoplasmic membrane); in contrast, T4 DNA in primary infected cells, like host DNA in uninfected E. coli, was found to be near the cell center. The envelope-associated DNA from super-infecting phage was not located on the outermost surface of the cell since it was insensitive to deoxyribonuclease added to the medium. These results suggest that DNA from superinfecting T-even phage is trapped within the cell envelope.     

flrB, a Regulatory Locus Controlling Branched-Chain Amino Acid Biosynthesis in Salmonella typhimurium

Salmonella typhimurium strain CV123 (ara-9 gal-205 flrB1), isolated as a mutant resistant to trifluoroleucine, has derepressed and constitutive levels of enzymes forming branched-chain amino acids. This strain grows more slowly than the parent at several temperatures, both in minimal medium and nutrient broth. It overproduces and excretes sizeable amounts of leucine, valine, and isoleucine in comparison with the parental strain. Both leuS (coding for leucyl-transfer ribonucleic acid [tRNA]synthetase) and flrB are linked to lip (min 20 to 25) by P1 transduction, whereas only leuS is linked to lip by P22 transduction. Strain CV123 containing an F' lip(+) episome from Escherichia coli has repressed levels of leucine-forming enzymes, indicating that flrB(+) is dominant to flrB. Leucyl-tRNA synthetase from strain CV123 appears to be identical to the leucyl-tRNA synthetase in the parent. No differences were detected between strain CV123 and the parent with respect to tRNA acceptor activity for a number of amino acids. Furthermore, there was no large difference between the two strains in the patterns of leucine tRNA isoaccepting species after fractionation on several different columns. Several other flrB strains exhibited temperature-sensitive excretion of leucine, i.e., they excreted leucine at 37 C but not 25 C. In one such strain, excretion at 37 C was correlated with derepression of some enzymes specified by ilv and leu. These latter results suggest that flrB codes for a protein.