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Biomedical subjects

R Thalmann

Publications and source records attributed to R Thalmann.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

Calcium gradients in inner ear endolymph.

Recent studies suggest that endolymphatic hydrops resulting from the ablation of the endolymphatic duct and sac in guinea pigs may be caused by a disturbance of endolymph calcium homeostasis. A similar disturbance of calcium homeostasis could represent the underlying cause of Ménière's disease. In this study, we mapped the calcium concentrations and electrical potentials throughout the endolymphatic system in normal guinea pigs. Large concentration differences exist between different compartments, including a more than twofold increase along the length of the cochlea. The electrochemical potential for calcium (the force driving passive longitudinal calcium movement) was calculated for all the endolymphatic compartments. The results show that endolymph is extremely inhomogenous with respect to calcium potentials. On the basis of these potentials, it appears that calcium is transported into endolymph in the cochlea and out of endolymph in the saccule and utricle. The possibility that endolymphatic hydrops arises from a disturbance in longitudinal flow of calcium, rather than in longitudinal volume flow, is considered.

Animals↗
PubMedDate not supplied

Otosclerosis: a local manifestation of a generalized connective tissue disorder?

The hypothesis that otosclerosis is a local manifestation of a clinically and genetically heterogeneous group of generalized connective tissue disorders was tested by quantitative biochemical techniques. In contrast to previous studies, no significant differences were found in individual glycosaminoglycans excreted in urine of control subjects and patients with otosclerosis. Moreover, no significant differences were detected in the rate of synthesis and secretion of glycosaminoglycans and collagen in skin fibroblast cultures of patients and controls. Preliminary results obtained with more sensitive and specific methods suggest a possible error in collagen metabolism. Polyacrylamide gel electrophoresis revealed slight differences in migration patterns of several collagenous proteins between patients and control subjects. In addition, collagenase was significantly increased in three of five patients.

Cells, Cultured↗