Search PubMed⌕ Search

Biomedical subjects

H Schmid

Publications and source records attributed to H Schmid.

At least 199 records · Page 11Linked to original sources
PubMed1982

Specific binding and pharmacological interactions of apamin, the neurotoxin from bee venom, with guinea pig colon.

This paper describes the interaction of apamin, the bee venom neurotoxin, with its receptor in the guinea pig colon. The pharmacological activity of the toxin was assayed by measuring its contracting effect on guinea pig colon preparations that had been previously relaxed by neurotensin. The IC50 value of apamin in this in vitro bioassay is 7 nM. These pharmacological data are compared to the binding properties of apamin to smooth muscle membranes prepared from guinea pig colon. The highly radiolabeled monoiododerivative of apamin binds to its colon receptor with a dissociation constant Kd* = 36 pM. The maximal binding capacity of colonic membranes is 30dfmol/mg of protein. The dissociation constant of the unmodified toxin is 23 pM. The difference between the toxin concentrations that produce half-maximal effects in the binding and pharmacological studies arises from the different experimental conditions used for the two assays.

Animals↗
PubMed1982

The Ca2+-dependent slow K+ conductance in cultured rat muscle cells: characterization with apamin.

The interaction of apamin, a bee venom neurotoxin, with rat skeletal muscle cell membranes has been followed using both an electrophysiological and a biochemical approach. Voltage-clamp analyses have shown that apamin, at low concentrations, specifically blocks the Ca2+-dependent slow K+ conductance in rat myotubes and myosacs . A specific binding site for apamin in rat muscle cell membranes has been characterized with the use of a highly radiolabelled apamin derivative [( 125I]apamin). The dissociation constant for the apamin-receptor complex is 36-60 pM and the maximal binding capacity is 3.5 fmol/mg of protein. [125I]Apamin binding to rat muscle membranes is displaced by quinine and quinidine with K0.5 values of 110 microM and 200 microM, respectively.

Action Potentials↗
PubMed1981

[Data analysis in health insurance].

In the last fifty years four to six mathematical research endeavours of general significance only have been designed in the field of health insurance. It is inconsequent to discuss the changes needed in the insurance system without having at one's disposal minimal mathematically-statistically firm basic figures. The present work first generally defines the mathematical bases in the health insurance field. The purpose of the project, within the first large scale data analysis, is above all the development of concepts for the institutionalized, systematic and periodical exploitation of the data available to health insurance carriers and their testing with econometric models. At the same time, thanks to methods to regularly collect data in the various health care sectors, the dependence of cost factors on medical care supply, on the structure of the insured population and on the cost causes will be studied at periodic intervals. Cheap sampling concepts shall be developed and tested in order to obtain the data which are not gathered directly. In a few fields data collection through surveys will be organized in order to allow for comprehensive interdisciplinary interpretation of the data.

Health Services↗
PubMed1980

Aldosterone in vitro restores nephron Na-K-ATPase of distal segments from adrenalectomized rabbits.

Aldosterone, when added in vitro to defined nephron segments, dissected from adrenalectomized rabbits, restores the depressed Na+-K+-ATPase activity in the thick ascending limb of the loop of Henle and in the cortical collecting tubule within 1 h of incubation. The direct effect is specific and, as demonstrated for the cortical collecting tubule, dose-dependent. The time course of aldosterone-mediated Na+-K+-ATPase activation is compatible with the conjecture of changes in the enzyme lipid environment.

Adrenalectomy↗
PubMed1980

Unchanged glycolytic capacity in rat kidney under conditions of stimulated gluconeogenesis. Determination of phosphofructokinase and pyruvate kinase in microdissected nephron segments of fasted and acidotic animals.

The glycolytic capacity in rat kidney was studied under conditions of stimulated gluconeogenesis like 48 h starvation and 48 h acidosis induced by force-feeding with a NH4Cl/glucose solution. Rats fed ad libitum and force-fed with a glucose solution served as controls. The specific activities of the key enzymes phosphofructokinase and pyruvate kinase were determined in single segments of the nephron. The determinations were performed by microdissection of lyophilized tissue sections followed by enzymatic analysis, including oil well technique, enzymatic amplification, and fluorometric measurement. In the distal portion of the nephron of both fed and force-fed animals a 10-fold higher specific activity of phosphofructokinase and pyruvate kinase was found compared with the proximal portion, known as the site of renal gluconeogenesis. Starvation and acidosis altered neither the distribution pattern nor the specific activities of these enzymes. From these results it is concluded that renal glycolysis does not undergo alterations at the level of enzymatic activities in favour of renal gluconeogenesis, probably because of the separate localization of both pathways within the nephron.

Acidosis↗
PubMed1979

New type of hepatic porphyria with porphobilinogen synthase defect and intermittent acute clinical manifestation.

In two young patients with acute hepatic porphyria syndrome and persisting paralyses, which increased in intensity during intermittent occurring crisis, the activity of erythrocyte porphobilinogen synthase (delta-aminolevulinic acid dehydratase) was found to be considerably diminished, below 1% of the value of normal control persons. In contrast, the activity of uroporphyrinogen synthase was normal. Both patients have been excreting high quantities of delta-aminolevulinic acid and porphyrins in urine for years. Lead intoxication has definitively been excluded. Since the relatives also show lower activities in porphobilinogen synthase, the disease of these two patients is probably a new enzymatic type of inherited acute hepatic porphyria, the excretion profile of which is qualitatively completely different from those of the known acute porphyrias. The discovery of this porphyria confirms the theory of overlapping transition in the biochemical and clinical symptoms and analogies among acute hepatic porphyrias.

Acute Disease↗
PubMed1979

Nephron electrolyte transport and sodium-potassium adenosine triphosphatase activity: influence of nicotine in rat and rabbit.

1. The influence upon mammalian renal epithelial transport of L-nicotine was studied in different types of experiments. 2. The kidney in situ (rat), when infused with nicotine (1 mg hr-1 kg-1 I.V.), lowered its absolute and fractional K+-absorption significantly and reversibly, but Na+-absorption did not change. Effects on glomerular function and an irreversible effect upon epithelial Na+ and K+ absorption were prevailing at higher infused amounts (10 or 50 mg hr-1 kg-1). 3. Single dissected nephron segments (collecting tubule, rabbit) were perfused in vitro, and the Na+ and K+-transtubular net flux was measured while L-nicotine (50 ng/ml.) had been added to the contraluminal side of the epithelium. Both, Na+-absorption and K+-secretion were decreased reversibly. 4. The activity of the Na+-K+-activated ATPase was significantly decreased in the cortical collecting tubule and in the proximal convoluted tubule of the rabbit after incubation of single in vitro dissected nephron segments with L-nicotine (50 or 100 ng/ml.). In contrast, nicotine added to a homogenate of renal cortical tissue had no effect on the Na+-transport enzyme or on key enzymes of glycolysis and gluconeogenesis. 5. These observations on the kidney in situ and on defined, perfused and non-perfused nephrons in vitro suggest that L-nicotine has dose-dependent, direct epithelial and mediated systemic effects on mammalian renal ion transport.

Animals↗
PubMed1979

[Hemolysis in ger test -- an alternative to hamagglutination inhibition test for search of antibodies against rubella virus (author's transl)].

640 sera of unknown immune status were tested in the rubella hemagglutination inhibition test (HI) as well as in hemolysis in gel test (HIG). The results have been analysed by statistical methods. The reproducibility of zones of hemolysis are 1.7 mm for the long term precision and 1.0 mm for the short term precision. Comparing the HIG and the HI tests we had a correlation of 97% = sensitivity (544 out of 561 sera) in positive reacting sera and of 87% = specifity (69 out of 79 sera) in the negative reactions. We consider a person to have antibodies against rubella if the zone of hemolysis had a diameter of 8 mm or above. In cases of diameters under 8 mm the results of IH and HIG-tests do not correlate. The reasons are not completely known and should be investigated.

Antibodies, Viral↗
PubMed1979

[Echocardiography in the elderly (author's transl)].

We report on questions and echocardiographic diagnoses in older patients and put out special views: value of ECG in coronary heart disease and in diagnosis of cardiomyopathy, for differentiation of systolic murmurs in the aged and detection of dilatation and atrial thrombosis.

Aged↗
PubMed1978

Movements in the sacroiliac joints demonstrated with roentgen stereophotogrammetry.

Using a roentgen stereophotogrammetric method, the three-dimensional movements in the sacroiliac joints were quantified in 4 patients. To provoke motion of the sacrum, changes between body positions and a test with manual pressure were used. In tests with symmetric forces on the sacrum, it in most cases rotated mainly about a transverse axis and at most approximately 2 degrees. The axis of rotation passed through the iliac bones mainly in the lower part of the iliac tuberosity. The rotations between the iliac bones and the sacrum about any of the three main axes were determined with a precision in the mean of 0.2 degrees. The distance between the two superior posterior iliac spines varied at most 0.4 mm between seven different body positions.

Adult↗