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Biomedical subjects

C Walther

Publications and source records attributed to C Walther.

At least 73 records · Page 4Linked to original sources
PubMed1982

[Antacids: A comparison of their in vitro neutralizing capacity in hydrochloric acid and in acidified peptone solution (author's transl)].

Using a simple and reproducible in vitro-test the neutralizing capacity of different liquid commercial antacids was measured at pH 2.0 and at pH 3.5 in diluted hydrochloric acid and in acidified peptone solution. In peptone solutions corresponding to postprandial gastric juice, antacids containing aluminum hydroxide and aluminate forming components demonstrated a marked loss in their neutralizing capacity when compared to peptone free hydrochloric acid as control. This loss in buffering capacity is dependent on the reaction time, the pH of the reaction mixture, the concentration of peptone in the solution and the amount of aluminum in the different antacid compounds. Furthermore the neutralizing capacity of aluminum hydroxide is also diminished by dibasic organic acids which mimicked fasting gastric juice in the experiment. The different availability of neutralizing potency of aluminum hydroxide containing antacids in acid and in acidified peptone solution will need to be considered when antacids are recommended for the treatment of patients with peptic ulcer disease.

Aluminum Hydroxide↗
PubMed1981

Synaptic terminals from an identified motoneuron in locust muscle: comparison between first instar larva and adult.

Dimensions and innervation of muscle fibers in locust jumping muscle from 1st instar larva and adult are compared. Fibers innervated by only one motoneuron were investigated. During postembryonic development, the size, but not the number, of muscle fibers increases. The number of synaptic contacts per fiber increases by at least one order of magnitude while the number per micron2 of surface membrane undergoes little change. Nerve terminals in the larva are on average shorter and separated by longer distances than in the adult. Synaptogenesis seems to be initiated by characteristic projections from the muscle attracting glial and axonal processes.

Animals↗
PubMed1978

Correlations between the morphological and clinical findings in a patient recovering from secondary generalised amyloidosis with renal involvement. Light- and electron microscopic investigations on serial biopsies.

We report light- and electron microscopic findings in glomerular amyloidosis (secondary amyloidosis), which occurred after recurrent empyema of the pleura. After healing of the empyema, the clinical symptoms disappeared, over a period of eight years. During the acute stage of the disease (grade II-III amyloidosis) when the nephrotic syndrome was present, amyloid deposits were seen in the mesangium and on both sides of the basement membrane of the glomerular capillaries. Furthermore, denuded basement membrane areas showing the passage of amyloid into the urinary space, and invaginations of the podocyte by straightened amyloid fibrils were found. After clinical recovery (except for a trace of proteinuria), the renal amyloidosis had electronmicroscopically transformed from an active into an inactive or resting form, while the amount of amyloid present was almost the same. In the areas of amyloid deposits, reparative changes were observed, espcially in the area of the mesangial cells and of the podocytes. The podocytes were separated from the persisting amyloid deposits by newly formed basement membrane material.

Adult↗
PubMed1978

Azidophenantridinium compounds as photoaffinity labels of cholinergic proteins.

The synthesis of diazidopropidium and diazidoethidium is described. The applicability of these compounds as photoaffinity labels for cholinergic proteins has been investigated: diazidopropidium inhibits neuromuscular transmission. This inhibition is reversible if the compound is applied in the dark but becomes irreversible after irradiation with white light. Inhibition is accompanied by a disappearance of miniature endplate potentials. Electrophysiological analysis of this effect indicates that diazidopropidium acts postsynaptically by blocking the acetylcholine receptors. At the molecular level the action of diazidopropidium and diazidoethidium on acetylcholinesterase has been investigated: both compounds appear to bind to a peripheral acetylcholine binding site of this enzyme. Binding of 125I-labeled alpha-neurotoxin from Naja naja siamensis to purified membranes from Torpedo californica electric tissue rich in acetylcholine receptors is diminished after incubation and irradiation with diazidopropidium. About half of the toxin binding sites appear to be blocked by the photoaffinity label.

Acetylcholine↗
PubMed1978

Aspects of turnover and biogenesis of synaptic vesicles at locust neuromuscular junctions as revealed by zinc iodide-osmium tetroxide (ZIO) reacting with intravesicular SH-groups.

Retractor unguis nerve muscle preparations from the locust were subjected to the zinc iodide-osmium tetroxide reaction (ZIO) after pre-fixation in glutaraldehyde. Applied for 18 h at 4 degrees C in the dark, ZIO reacts at pH 4.2--4.0 fairly selectively with the matrix of synaptic vesicles. Approximately 53% of the vesicles are completely and 4% partially stained. The percentage of ZIO-positive vesicles is increased to nearly 90% and reduced to 4% or less by pretreatment with SH-protecting (dithiothreitol) or SH-blocking (N-ethylmaleimide, p-chloromercuriphenyl sulfonic acid) and SH-oxidizing (azodicarboxylic acid-bis-dimethylamide) reagents, respectively. Stimulation of the motor nerve at 20 Hz for 7 min, partially fatiguing synaptic transmission, reduces the number of vesicles per square micrometer of terminal area by approximately 52%; 2 min of rest restores this number of its pre-stimulation level. These changes are chiefly accounted for by changes in the number of completely ZIO-positive vesicles. 2 min after the end of stimulation, partially ZIO-positive vesicles are three times more frequent than before. With all experimental conditions, the average volume of vesicles was as follows: ZIO-negative less than partially ZIO-positive less than completely ZIO-positive. The average volume of ZIO-positive vesicles is almost unaffected by stimulation; that of ZIO-negative vesicles is decreased by 25% immediately after stimulation, increasing with subsequent rest to the initial level after 1 h. It is suggested (a) that ZIO demonstrates intravesicular protein(s) containing SH-groups and (b) that the completely ZIO-positive vesicles represent the mature ones ready to be used for transmitter release. How the ZIO reaction differentiates between different developmental stages of vesicles which could arise from the smooth endoplasmic reticulum is discussed.

Animals↗
PubMed1976

Junctional and extrajunctional acetylcholine receptors in normal and denervated frog muscle fibres. Noise analysis experiments with different agonists.

Ionic channel properties of acetylcholine receptors located in, in the vicinity of, or far away from a frog neuromuscular junction were investigated by noise analysis of drug induced current fluctuations. For drugs applied to the junction, in certain cases two Lorentzian curves were necessary to describe the data. It is postulated that the reason for this observation is that a contribution from perijunctional receptors was being observed. The conductance of a single channel in the junction was independent of the nature of the agonist and had an average value of 17.9 pS (temperature range 8-25 degrees C, solution buffered with Tris). After denervation for 21 days the conductance gamma was 7.5 pS at extrajunctional locations. In the close neighbourhood of the junction (peri-junctional receptors) values were found between 4 and 19 pS. The mean value of the open channel life-time tau in the endplate exposed to acetylcholine was 2.4 ms at 8-11 degrees C. This value was 0.90 ms with carbachol, 0.50 ms with succinylcholine, 0.28 ms with decamethonium and 0.45 ms with nicotine. The receptors outside the endplate exhibited tau-values which at a given temperature were 2-3 times larger than those at the endplate. Raising the temperature to 23 degrees C reduced all tau-values by factors of 2-3. It is concluded that at least two types of ACh-receptors with different properties exist in the muscle membrane, possibly produced by ACh-receptive units in different states of aggregation.

Acetylcholine↗
PubMed1976

[Anticoagulants and fibrinolytics in pregnancy].

1. Cumarin-derivates are said to be contraindicated during pregnancy. 2. Heparin, and heparinoides certainly took may be given during pregnancy. 3. Streptokinase is recommended--if indicated--also during pregnancy.

Abnormalities, Drug-Induced↗
PubMed1975

[The treatment of thrombosis in pregnancy (author's transl)].

The treatment of thrombophlebitis in pregnancy with streptokinase is reviewed. Four personal cases are reported. In 3 cases the streptokinase treatment of thrombosis was carried out in the first trimester of pregnancy. Two pregnancies ended in spontaneous term deliveries of well infants without malformations. In one case the pregnancy ended by a spontaneous abortion two weeks following the treatment of the thrombosis. It is suggested that the abortion was much more likely due to a severe state of shock with pulmonary embolism following laparotomy in early pregnancy. The authors are of the opinion that the thrombolytic therapy with streptokinase should also be carried out in the first trimester of pregnancy to prevent embolization of thrombotic material and to prevent a post-thrombotic syndrome. In each case, streptokinase treatment should be followed up with subcutaneous prophylactic treatment with Heparin until term to prevent recurrent thrombophlebitis in pregnancy. With the onset of labour Heparin medication should be interrupted and the thrombin time should be normal with the beginning of the second stage of labour or the Heparin effect should be neutralized by protamine chloride. At the earliest six hours postpartum, the subcutaneous Heparin prophylaxis can be resumed in order to prevent recurrent thrombo-embolism during the postpartum stay.

Abortion, Spontaneous↗