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Biomedical subjects

H Winkler

Publications and source records attributed to H Winkler.

At least 289 records · Page 16Linked to original sources
PubMed1980

Uptake of nucleotides and catecholamines by chromaffin granules from pig and horse adrenal medulla.

The uptake of nucleotides and catecholamines into chromaffin granules from adrenals of pigs and horses is similar to that previously seen in bovine chromaffin granules. The rate of [3H]ATP uptake at 2 mM-ATP concentration was 0.42 +/- 0.06 and 0.15 +/- 0.02 nmol/mg protein/min for pig and horse granules, respectively. The apparent Km's were 1.37 mM for pig granules, 0.89 mM for horse granules, and 1.2 mM for ox granules. The sensitivity of the uptake for nucleotides and catecholamine to specific inhibitors was found to be similar in granules from pig and ox, indicating that the same mechanisms of uptake are involved in both species.

Adenosine Triphosphate↗
PubMed1978

Particle segregation in chromaffin granule membranes by forced physical contact.

Bovine chromaffin granules were exposed to different isotonic non-ionic and ionic solutions (sucrose; Ca2+- and Mg2+-free phosphate-buffered saline; Tris-HCl + NaCl; Ca2+- and Mg2+-free phosphate-buffered saline + sucrose; Tris-HCl + sucrose) at pH 7 and then frozen either in suspension or as firm pellets. Freezing was performed without prefixation or antifreeze treatments either by 'standard' techniques (approx. 1 mm3 suspended or pelleted material on gold specimen supports dipped into liquid Freon) or with increased cooling rates by spraying suspensions into liquid propane ('spray-freezing'). Regardless of the freezing method, membrane-intercalated particles were always randomly distributed when chromaffin granules were frozen in suspension. In contrast, forced physical contact between granules produced by centrifugation (12000 X g, 25 min) provoked dispersal of membrane-intercalated particles, but only in the presence of ions. Sucrose or EDTA in an ionic environment had no inhibitory effect. The following conclusions are derived: (1) Even below the reported phase transition region particle clustering is possible. (2) Chromaffin granule membranes are not liable to thermotropic segregation of membrane-intercalated particles. (3) Although the low freezing rates of 'standard' freezing techniques produce large-scale segregation artefacts (by which suspended chromaffin granules are pushed together within the segregated solute) this does not result in intramembraneous particle segregation. (4) Forced physical contact produces a Ca2+-independent particle segregation, but only when repulsive electrostatic forces of membrane components are partially screened in an ionic environment. (5) This does not invalidate results obtained by others, showing Ca2+-mediated chromaffin granules agglomeration and segregation of membrane-intercalated particles, but it might indicate the occurrence of another, not directly Ca2+-dependent particle segregation mechanism in a prefusional stage of close membrane-to-membrane contact during exocytosis.

Animals↗
PubMed1978

A characterization of the nucleotide uptake of chromaffin granules of bovine adrenal medulla.

Chromaffin granules isolated from bovine adrenal gland were incubated with (3)H-labelled nucleotides and [(14)C]noradrenaline to study the uptake of these substances. [(3)H]ATP, [(3)H]ADP and [(3)H]AMP are taken up by these organelles by the same temperature-dependent mechanism. The apparent K(m) for ATP and ADP is 1.4mm, and for AMP it is 2.9mm. The uptake of ATP has a flat pH optimum, whereas the catecholamine uptake increases with more alkaline pH. Atractyloside and carboxyatractyloside are competitive and specific inhibitors of nucleotide uptake, whereas reserpine inhibits only that for catecholamines. Mg(2+) ions activate uptake of both catecholamine and nucleotides, whereas EDTA and N-ethylmaleimide inhibit these processes. Nucleotide and catecholamine uptakes are inhibited by uncouplers of oxidative phosphorylation and by two ATP analogues. NH(4) (+) ions and nigericin in the presence of KCl inhibit only catecholamine uptake. It is concluded that nucleotide uptake, as proposed previously for catecholamine uptake, depends on an electrochemical proton gradient produced by a proton-translocating adenosine triphosphatase localized in the membrane of chromaffin granules. Furthermore, as suggested by the effect of NH(4) (+) and nigericin, catecholamine uptake apparently depends on the chemical part of this gradient, whereas the results for nucleotide uptake are consistent with its dependence on the electrical component.

Adenosine Diphosphate↗
PubMed1978

The distribution of sulfamerazin between plasma, cerebrospinal fluid, and bile in humans.

The concentration-time curves of sulfamerazin were determined in plasma, cerebrospinal fluid (c.s.f.) and bile in two groups of patients (ventricle drainage and Kerr's T-tube drain). In plasma, a half-life of 13.6 hours as well as an invasion and evasion constant of 0.145 hours -1 and 0.051 hours -1, resepectively, were observed. The distribution of half-life times showed a bimodal behavior in these patients. The unbound part of sulfamerazin was 12% and the acetylated products 14%. Unlike plasma in c.s.f. and bile the influx is delayed up to steady state. The decreases of concentration in all three compartments are the same. The concentration ratio of sulfamerazin between C.S.F. and bile and plasma water amounted to 1 and 2.5, respectively. Of the given dose of sulfamerzin, 0.87% was eliminated by bile within 24 hours. The therapeutic conclusions are discussed with regard to the bimodal distribution of half-lives, the minimal inhibition concentrations and the unbound part in the plasma.

Acetylation↗
PubMed1978

The distribution of lithium into cerebrospinal fluid, brain tissue and bile in man.

The concentration of lithium was determined in plasma, cerebrospinal fluid (CSF) and bile in two groups of 5 and 6 patients after oral administration of lithium carbonate (0.2 mVal/kg b.w.) in each group. In a third group of 7 patients the lithium concentration in the brain and also in the CSF and the plasma was determined in the steady state. The influx into CSF was delayed in contrast to that into plasma and bile. The elimination was biexponential. The mean plasma half-life of lithium carbonate was 21 hours. The concentration ratio between CSF and bile, respectively, and plasma was 0.44 +/- 0.03 and 1.48 +/- 0.36 in steady state. Two percent of the given dose was eliminated with the bile within 24 hours. There was no concentration difference in steady state between that for CSF and both white and grey brain matter. It is suggested that the concentration of lithium in CSF represents the brain concentration.

Adolescent↗
PubMed1977

[Investigations about cause of specific replant disease of fruit trees. VI. Proof of actinomycetes in feeder roots of apple seedlings in soils with different digrees of soil sickness (author's transl)].

Microscopic analysis of longitudinal sections of feeder roots of apple seedlings from soil with experimentally prepared different degrees of soil sickness led to the following results: 1. A colonization of root-barks by actinomycetes could be pointed out in injured and in macroscopic not visible injured feeder roots of apple seedlings from sick soil. 2. The frequency of the colonization of root-pieces of the two highest root classes was in the sick soil at 47.3% and in the two soils with a less degree of soil sickness at 32.4%. In the non-sick soil the root were at a frequency of 0.3% nearly free from actinomycetes. 3. Feeder roots colonizated by actinomycetes showed injuries in the cell-bandage. Increasing injuries of the roots were obtained with increasing intensity of colonization by actinomycetes. In heavy injured feeder roots the proof of actinomycetes was difficult or no more possible. As the share of heavy injured roots was increasing with increasing degree of soil sickness can be supposed that the real frequency of root colonization by actinomycetes is substantially higher than it was observed in roots seeming to be healthy macroscopically. 4. The results obtained support our hypothesis that soil sickness of apple trees is caused by actinomycetes. The injuries of the roots appearing as a consequence of the colonization may explain both, the soil sickness in the case of replanting and the development of soil sickness in growing apple plantations. 5. Since until now there is no proof that actinomycetes cause injuries in roots of fruit-trees further examinations have to be aspired to confirm our results.

Actinomycetales↗