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Biomedical subjects

R Thalmann

Publications and source records attributed to R Thalmann.

At least 91 records · Page 5Linked to original sources
PubMed1978

[Surgical therapy of axial hiatal hernias and reflux disease. 1. Results of an inquiry among Swiss surgeons in 1977].

Of the 153 heads of surgical departments in Switzerland, 152 joined in an inquiry into diagnostic procedures, surgical indications, and types of procedure in the treatment of axial hiatal hernia and reflux disease. Fundoplication is by far the most frequent procedure. Of the modifications performed in complicated reflux disease, 34% are controversial. Surgery for hiatal hernia and reflux disease is performed 3 times less frequently in the German part of Switzerland than in the other parts. German-speaking surgeons ascribe to themselves a greater willingness to perform preoperative diagnostic procedures--endoscopy, radiological and non-radiological tests of esophageal function--than the surgeons of the other parts of Switzerland. However, the German-speaking surgeons are more reluctant than the other surgeons to perform surgery in patients with esophagitis. The German-speaking surgeons are even more reluctant to perform surgery on the basis of subjective symptoms. Axial hiatal hernia is considered a relative indication for surgery by half of Swiss surgeons. Only a few surgeons consider this condition an absolute indication for surgery.

Cardia↗
PubMed1978

Respiratory rate and ATP content of stria vascularis of guinea pig in vitro.

Stria vascularis from guinea pig cochleae was incubated in vitro to determine its metabolic response to variations in substrate and ion composition of the incubation medium. The respiratory rate at 37 degrees C in a medium containing glucose and pyruvate as substrate was 17.3 +/- 1.33 (SEM, n = 51) microliter O2/mg dry weight-hour. The stria could not maintain constant respiration by relying solely upon endogenous fuel stores. With substrate supplied, the ATP level could be maintained at about 73% of that existing in vivo. Glucose appears to be an adequate substrate for stria in vitro since glutamate, pyruvate, and fumarate did not increase the respiratory rate. Succinate increased respiration markedly but did not increase the ATP level. Ouabain (10(-4) M) caused a 48% decrease in the respiratory rate. Incubation in Na+-free and K"-free medium, each resulted in irreversible decrease of respiratory rate comparable to (or greater than) that caused by ouabain. These data are in accord with the high activity of Na+-K+-ATPase in the stria and the pronounced sensitivity of the endolymphatic potential to ouabain.

Adenosine Triphosphate↗
PubMed1978

Adenylate energy charge, energy status, and phosphorylation state of stria vascularis under metabolic stress.

The purpose of the reported experiments was to measure the strial concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP), and adenosine monophosphate (AMP) in order to arrive at estimates of three commonly used adenylate ratios. Under normal conditions, the concentrations of ATP, ADP, and AMP were found to be 11.4, 3.7, and 0.6 mmoles/kg dry weight, respectively. Of the three substances, AMP is the most sensitive indicator of metabolic stress, since its concentration doubles within 6 sec. of ischemia and reaches a peak level of about 1500% of the control following 65 sec. of ischemia. Under normal conditions, the "adenylate energy charge," the "energy status," and the "phosphorylation state" amount to 0.84, 3.0, and 1.52 gram wet weight/mumole, respectively. In ischemia of 10 min. duration, the adenylate energy charge decreases 3 fold, the energy status 7 fold and the phosphorylation state 14 fold. The size of the adenylate pool shows a slight increase in the earliest stage of ischemia, but declines progressively thereafter. The apparent equilibrium constant of strial adenylate kinase was found to be 0.48. The advantages and limitations of the different adenylate ratios, as indicators of metabolic health and as regulatory parameters, are discussed.

Adenosine Diphosphate↗
PubMed1977

Noxious effects upon cochlear metabolism.

The influence of various toxic substances and of drugs with ototoxic side effects upon energy generation, energy utilization, and membrane processes of the cochlea were studied. None of the drugs tested interfered with energy generation to as great an extent as did anoxia or cyanide and 2,4-dinitrophenol. Ouabain produced a pronounced interference with energy utilization of the stria vascularis. The "loop" diuretics ethacrynic acid and furosemide produced a reduction of energy utilization of a lesser degree than did ouabain. The "loop" diuretics do not seem to exert their toxic action upon strial Na+K+-ATPase, but may act by interfering with strial adenylate cyclase. Aminoglycoside antibiotics and diuretic and nondiuretic mercurials seem to exert their primary noxious action upon cochlear function by interfering with membrane processes of the structures bounding the cochlear duct.

Action Potentials↗
PubMed1976

Effects of anoxia and ethacrynic acid upon ampullar endolymphatic potential and upon high energy phosphates in ampullar wall.

The ampullar endolymphatic potential (AEP) was studied in the guinea pig during ischemia and asphyxia and following systemic application of ethacrynic acid. In addition the specialized and nonspecialized portions of the ampullar wall were analyzed for ATP and P-creatine at different conditions of metabolic interference. Under control conditions the AEP amounted to + 4.6 +/- 1.2 mV. In both types of hypoxia the decline of the AEP proceeded on a much slower time scale than that of the cochlear endolymphatic potential (CEP), and the maximum negativity reached was considerably less. Quantitative analysis of both types of ampullar wall tissue indicated a much slower decline in hypoxia of ATP levels than in the stria vascularis. Changes in P-creatine levels were considerably more rapid. The AEP became reduced and changed polarity also by intoxication with ethacrynic acid (EA), but higher dosages (above 70 mg/kg) were necessary than for effects upon the CEP and much longer time periods were required for attainment of maximum negativity. The maximum negativity of the AEP was significantly greater at a dosage of 100 mg/kg of EA than during ischemia. At the point of maximum depression of the AEP P-creatine levels in both types of ampullar tissue were unchanged, but ATP levels were significantly reduced in the specialized portions of ampullar wall.

Action Potentials↗
PubMed1975

Cyclic AMP and adenylate cyclase in the inner ear.

The activity of adenylate cyclase and the steady state levels of cyclic AMP (cAMP) were determined in stria vascularis (SV) and organ of Corti (OC) of the guinea pig cochlea. The activities are 12 and 19 pmoles/mg dry weight/minute for OC and SV, respectively. The activity was increased two to four-fold by NaF. The base level of cAMP is 4.2 and 4.4 nmoles/g dry weight in OC and SV, respectively. In contrast to brain, neither ischemia nor barbiturates produced major changes of the steady state levels of cAMP. No in vitro effect of cAMP upon the state of activation of glycogen phosphorylase was noticeable in either tissue. cAMP did not exert a significant in vitro inhibition of strial Na+K+-ATPase. Perilymphatic perfusion of cAMP (10-3 M) and of theophylline (5 times 10-3 M) did not produce changes in the endolymphatic potential (EP), but dibutyryl cAMP (10-3 M) led to a significant increase of EP. The alpha adrenergic blocking agent, phentolamine, produced very complex changes of the cochlear potentials. A possible role of catecholamines and cAMP in the secretory phenomena of the SV and in the transduction and/or transmission processes of the auditory sense organ are discussed.

Action Potentials↗