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  • Life and Medical Sciences  (3)
  • Alzheimer's disease  (2)
  • 1
    ISSN: 1432-2072
    Keywords: Alzheimer's disease ; Aging ; Scopolamine ; Transient visual evoked potentials
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Transient visual evoked potentials elicited by the onset of a patterned stimulus were recorded in patients suffering from Alzheimer's disease (AD), in healthy elderly controls and in healthy young individual. The latencies and amplitudes of both the components studied were adversely affected by normal aging and one of the components, CI, but not the other, CII, showed further deterioration in AD. These changes occurred over a range of stimulus contrast levels. The changes found in AD, but not those seen in normal aging, could be mimicked by administration of the cholinergic antagonist scopolamine to young volunteers.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2072
    Keywords: Nicotine ; Alzheimer's disease ; Attention ; Information processing ; Short-term memory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This single-blind, placebo controlled study reports on the effects of administering three acute doses of nicotine (0.4, 0.6 and 0.8 mg) subcutaneously to a group of Alzheimer's disease (DAT) patients (n=22), young adult controls (n=24), and normal aged controls (n=24). The study extends our previous findings obtained using smaller groups of subjects. Drug effects were examined on three computerised tests: the first measuring rapid visual information processing, sustained visual attention and reaction time (RVIP task); a delayed response matching to location-order task measuring sustained visual attention and visual short-term memory (DRMLO task); and a finger tapping test measuring simple reaction time (FT task). The critical flicker fusion test (CFF) was used as a measure of perception and the WAIS digit span forwards (DS), of auditory short-term memory. Tests were graded in difficulty, titrated to avoid floor and ceiling effects so that meaningful, direct comparisons between groups could be made. Nicotine significantly improved sustained visual attention (in both RVIP and DRMLO tasks), reaction time (in both FT and RVIP tasks), and perception (CFF task — both ascending and descending thresholds). Nicotine administration did not improve auditory and visual short-term memory. There were no consistent, overall patterns of difference in performance between smokers and non-smokers in the control groups, or between males and females in any group. Despite the absence of change in memory functioning, these results demonstrate that DAT patients have significant perceptual and visual attention deficits which are improved by nicotine administration. The importance of measuring multiple abilities in future drug studies is emphasized and results are discussed in terms of nicotine's actions on attention, information processing and short-term memory.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 104 (1980), S. 425-431 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Viable cell samples containing 93% pure granulocytes were obtained from human blood using the techniques of dextran sedimentation followed by centrifugal elutriation. The resting transmembrane potential (Em) of human granulocytes was estimated using the fluorescent lipophilic cation, Di-S-C3(5), from the null point for potassium - i.e., the external K concentration at which there is no change in Em in response to valinomycin (a K ionophore). The Em of human granulocytes, as calculated from the Nernst potential for K at the null point, is approximately - 100 mV. Data indicate that this large transmembrane potential is due in part to the presence of an electrogenic Na-K pump in human granulocytes which is stimulated by external potassium and inhibited by ouabain.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 106 (1981), S. 75-83 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Treatment of human granulocytes with concanavalin A, phorbol myristate acetate (PMA), N-formyl-methionyl-leucyl-phenylalanine (FMLP), and A23187 (a calcium ionophore) stimulates the release of superoxide anion and the generation of chemiluminescence. The fluorescent probe, Di-S-C3(5), has been used to monitor shifts in membrane potential in response to these stimulants which precede the secretion of superoxide. Concanavalin A, PMA, and FMLP induce a biphasic shift in transmembrane potential (Em), i.e., a rapid depolarization followed by a prolonged hyperpolarization. This depolarization is dependent on both external sodium and calcium while the hyperpolarization is inhibited by ouabain which blocks the electrogenic Na-K pump. In contrast, A23187 induces a rapid and prolonged depolarization. This monophasic shift in Em is dependent on external calcium. These results suggest that depolarization acts as a signal to initiate events associated with the “respiratory burst” of these phagocytes.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0749-503X
    Keywords: Hansenula ; haemoglobin ; integration ; continuous culture ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Recombinant human haemoglobin A (rHbA) was produced by a leucine-requiring strain of Hansenula polymorpha which had been transformed with an integration vector containing the Saccharomyces cerevisiae LEU2 gene and cDNAs for the expression of α and β globin each driven by the H. polymorpha MOX promoter. After 40 generations in a chemostat it was found that the integrated vector had become amplified in the host strain. In some cases this led to an increase in LEU2 gene dosage, but a loss of globin expression cassettes. In other cases the globin gene dosage also increased. These changes coincided with an increase in rHbA production in the culture, which was reversed when the dilution rate was increased. Isolates from a chemostat culture producing elevated levels of rHbA were grown in fed-batch fermentations, resulting in higher productivities than when inoculated with the parent strain. The rHbA produced was purified and characterized. Oxygen binding studies and electrospray mass spectrometry showed that the rHbA had been processed and assembled correctly, and behaved as a fully functional co-operative tetramer.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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