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  • 1
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Butyrivibrio fibrisolvens strains D1 and A38 produced little lactate, but strain 49 converted as much as 75% of its glucose to lactate. Strain 49 had tenfold more lactate dehydrogenase activity than strains D1 or A38, this activity was stimulated by fructose 1,6-bisphosphate, and had a pH optimum of 6.25. A role for fructose 1,6-bisphosphate or pH regulation of lactate production in strain 49 was, however, contradicted by the observations that very low concentrations (〈 0.2 mM) of fructose 1,6-bisphosphate gave maximal activity, and continuous cultures did not produce additional lactate when the pH was decreased. The lactate production of strain 49 was clearly inhibited by the presence of acetate in the growth medium. When strain 49 was supplemented with as little as 5 mM acetate, lactate production decreased dramatically, and most of the glucose was converted to butyrate. Strain 49 did not possess butyrate kinase activity, but it had a butyryl-CoA/acetate CoA transferase that converted butyryl-CoA directly to butyrate, using acetate as an acceptor. The transferase had a low affinity for acetate (K m of 5 mM), and this characteristic explained the acetate stimulation of growth and butyrate formation. Strains D1 and A38 had butyrate kinase but not butyryl-CoA/acetate CoA transferase, and it appeared that this difference could explain the lack of acetate stimulation and lactate production. Based on these results, it is unlikely that B. fibrisolvens would ever contribute significantly to the pool of ruminal lactate. Since relatives of strain 49 (strains Nor37, PI-7, VV1, and OB156, based on 16S rRNA sequence analysis) all had the same method of butyrate production, it appeared that butyryl-CoA/acetate CoA transferase might be a phylogenetic characteristic. We obtained a culture of strain B835 (NCDO 2398) that produced large amounts of lactate and had butyryl-CoA/acetate CoA transferase activity, but this strain had previously been grouped with strains A38 and D1 based on 16S rRNA sequence analysis. Our strain B835 had a 16S rRNA sequence unique from the one currently deposited in GenBank, and had high sequence similarity with strains 49 and Nor37 rather than with strains A38 or D1.
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  • 2
    ISSN: 1432-2277
    Keywords: Key words Liver conditioning ; Cardiac arrest ; liver donation ; Normothermic recirculation ; Liver transplantation ; experimental
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aim of this study was to compare the possible role of normothermic recirculation with the role of liver transplants from non-heart-beating donor pigs after 20 min of cardiac arrest. Three groups were studied, of which two were control groups: group 1, in which the liver was harvested from a heart-beating donor; group 2, in which the liver was harvested after a period of cardiac arrest followed by total body cooling; and group 3, in which the liver was procured as in group 2, but including a period of 30 min of cardiopulmonary bypass and tissue oxygenation at 37 °C before total body cooling. Survival at 5 days; endothelial (hyaluronic acid) and hepatocellular damage (AST, ALT, and α-GST); adenine nucleotides (energy charge), and histological changes were evaluated. Normothermic recirculation during 30 min showed a significant effect on survival (p = .03), endothelial damage (p 〈 .05), and histological changes after reperfusion (p = .04). Cardiopulmonary bypass significantly increased the energy charge during the normothermic recirculation period (p = .001). Moreover, this study shows that a significant survival (100 %) can be achieved with a liver allograft after 20 min of cardiac arrest. Although the liver suffers a major insult in terms of endothelial damage and hepatocellular damage, lesions caused by the ischemic injury are reversible. Histological changes also indicate lesion reversibility, since they almost disappear after 5 days.
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  • 3
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The effect of inorganic phosphate concentrations on antibiotic and extracellular protein production by Myxococcus coralloides D have been examined. Antibiotic production by growing cells of this myxobacterium was maximal at phosphate concentrations of 10–20 mM, but was inhibited by concentrations higher than 20 mM. The total extracellular protein and the extracellular protein per cell ratio were independent of phosphate levels in the culture broth.
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  • 4
    ISSN: 1442-2042
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The α1-adrenoceptor antagonist doxazosin has proved successful in treating patients with concurrent benign prostatic hyperplasia (BPH) and hypertension in short-term studies. However, both conditions are chronic and may worsen over time. The aim of this study was, therefore, to examine the tolerability and efficacy of doxazosin in the long-term treatment of concurrent BPH and hypertension. Methods: This study was a longitudinal extension of earlier double-blind trials. Patients were enrolled into the study on a rolling basis. From a total of 178 BPH patients with hypertension enrolled into the study, 28 had reached 48 months of open-label treatment with doxazosin at the time of the final data cutoff. Results: Treatment with doxazosin resulted in sustained benefits for BPH patients over the whole study period, with significant improvements in the severity (12.2%, P 〈 0.001) and bothersomeness (13.2%, P 〈 0.001) of BPH symptoms, and in the maximum urinary flow rate (26.6%, P 〈 0.05) from baseline to the end of the 4-year period. There was also a significant and sustained reduction in diastolic blood pressure. The efficacy of doxazosin treatment for both BPH and hypertension was maintained over the 4-year period, despite the tendency of these conditions to worsen with time. Comparison of adverse events in patients with long- and short-term hypertension and BPH demonstrates that the safety of doxazosin is not altered during long-term therapy. Conclusions: This study demonstrates that doxazosin appears to be well tolerated and efficacious in the long-term management of concurrent BPH and hypertension.
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  • 5
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Binocular disparities are crucial for building an accurate three-dimensional representation of the peripersonal environment in a viewer-centred frame of reference. Previous studies have shown that visual cells of the medial superior temporal cortex (MST) have large receptive fields and that they are sensitive to disparities present in large surfaces. By using a reverse cross-correlation technique in this study we tested 175 disparity-sensitive units recorded from MST in the awake Macaca mulatta monkey to determine if these large receptive fields are homogeneous in terms of disparity sensitivity. We found that the receptive fields of 50 cells (50 out of 175, 29%) showed subregions with specific disparity sensitivity. These subregions presented eccentricities from 0.8 to 22.3° and their sizes varied from 1.6 to 15.3°2. This particular receptive field organization represents a suitable mechanism for encoding the location of small objects within our peripersonal space.
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  • 6
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Due to the separation of the eyes, temporal retinal disparities are created during binocular stimulation and they have been proposed to be the basis of several stereo-visual effects. This paper studies the sensitivity of cortical neurons from area V1 to interocular temporal delay in the awake monkey (Macaca mulatta). Forty-four cells were included in this study. Temporal delay sensitivity was observed in 59% of them. About half of these temporal-delay-sensitive cells were also sensitive to the stimulation sequence of the eyes. The cells that preferred one eye to be stimulated first were termed asymmetrical (46%); those which were not sensitive to the eye sequence of stimulation were termed symmetrical (54%). No clear differences were observed in the distribution of delay-sensitive cells according to their eye dominance. Fifty-six percent of balanced cells and 65% of unbalanced cells were sensitive to interocular delay. These data underline the importance of temporal cues for depth perception.
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  • 7
    ISSN: 1432-072X
    Keywords: 13C-NMR ; Glucokinase ; Polyphosphate ; Myxococcus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polyphosphate glucokinase and ATP glucokinase were detected in cell-free extracts of Myxococcus coralloides strain D, but pyrophosphate glucokinase was not detected. Both glucokinase activities were separated by chromatography. The approximate molecular weight is 61 000 for polyphosphate glucokinase and 47 000 for ATP glucokinase. Substrate specificity and pH optimum was studied in the polyphosphate glucokinase. Polyphosphate and ATP glucokinase activities were verified by 13C Nuclear Magnetic Resonance.
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  • 8
    ISSN: 1432-072X
    Keywords: Key wordsClostridium acetobutylicum ; Lactate ; utilization ; Acetate utilization ; Acetone-butanol ; fermentation ; Lactate dehydrogenase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clostridium acetobutylicum strain P262 utilized lactate at a rapid rate [600 nmol min–1 (mg protein)–1], but lactate could not serve as the sole energy source. When acetate was provided as a co-substrate, the growth rate was 0.05 h–1. Butyrate, carbon dioxide and hydrogen were the end products of lactate and acetate utilization, and the stoichiometry was 1 lactate + 0.4 acetate → 0.7 butyrate + 0.6 H2 + 1 CO2. Lactate-grown cells had twofold lower hydrogenase than glucose-grown cells, and the lactate-grown cells used acetate as an alternative electron acceptor. The cells had a poor affinity for lactate (Ks = 1.1 mM), and there was no evidence for active transport. Lactate utilization was catabolyzed by an inducible NAD-independent lactate dehydrogenase (iLDH) that had a pH optimum of 7.5. The iLDH was fivefold more active with d-lactate than l-lactate, and the K m for d-lactate was 3.2 mM. Lactate-grown cells had little butyraldehyde dehydrogenase activity, and this defect did not allow the conversion of lactate to butanol.
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  • 9
    ISSN: 1432-072X
    Keywords: Clostridum acetobutylicum ; Acetate kinase ; Acetate utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clostridum acetobutylicum strain P262 fermented glucose, pyruvate, or lactate, and the butyrate production was substrate-dependent. Differences in butyrate yield could not be explained by changes in butyrate kinase activities, but the butyrate production was inversely related to acetate kinase activity. The acetate kinase had a pH optimum of 8.0, aK m for acetate of 160 mM, and ak cat of 16,800 min-1. The enyzme had a native molecular mass of 78 kDa; the size of 42 kDa on SDS-PAGE indicated that the acetate kinase of strain P262 was a homodimer.
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  • 10
    ISSN: 1432-072X
    Keywords: Key wordsClostridum acetobutylicum ; Acetate kinase ; Acetate utilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clostridum acetobutylicum strain P262 fermented glucose, pyruvate, or lactate, and the butyrate production was substrate-dependent. Differences in butyrate yield could not be explained by changes in butyrate kinase activities, but the butyrate production was inversely related to acetate kinase activity. The acetate kinase had a pH optimum of 8.0, a K m for acetate of 160 mM, and a k cat of 16,800 min–1. The enyzme had a native molecular mass of 78 kDa; the size of 42 kDa on SDS-PAGE indicated that the acetate kinase of strain P262 was a homodimer.
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