Biomedical subjects
Publications and source records attributed to U Gerhardt.
Surface carbohydrates of Mycoplasma mycoides var. capri were made visible by the cytochemical staining procedure with concanavalin A, horseradish peroxidase, and diaminobenzidine.
Electron spin resonance measurements were performed in order to investigate the influence of anti-cardiolipin antibodies on cardiolipin-containing liposomes. The physical state of the lipid structures and the alterations caused by the interaction with specific antibody were determined by measuring the freedom of motion of spin-labeled stearic acid derivatives incorporated into the lipid structures. The interaction of the cardiolipin-containing liposomes with the anti-cardiolipin antibodies reduced the mobility of the spin-labeled stearic acid probe I (12, 3), whose nitroxide group is assumed to be located near the polar region of the lipid bilayer. The restricted mobility, which qualitatively resembles the interaction of cardiolipin liposomes with calcium ions, is probably the result of a tighter packing of the polar groups in their crystalline array. The binding sites of the cardiolipin structures for anti-cardiolipin antibodies and Ca2 ions seem to be identical. As indicated by the spin-labeled stearic acid probe I (1, 14), the apolar region of the lipid bilayer is not affected by the interaction of the cardiolipin-containing liposomes with the anti-cardiolipin antibodies.
Phosphatidylglycerol is the main component (87%) of the membrane phospholipids of Mycoplasma hominis. It is immunologically active. Antibodies directed against phosphatidylglycerol were detected in rabbits intravenously immunised with native M. hominis or isolated M. hominis membranes. The intravenous method of immunisation was chosen in order to select for a response to surface antigenic determinants. Anti-phosphatidylglycerol antibodies were induced in rabbits by intravenously injecting the flocculated complexes of methylated bovine serum albumin and a phosphatidylglycerol/phosphatidylcholine/cholesterol mixture. These antibodies were specifically bound to intact M. hominis, as shown by complement fixation and Coombs tests. Native M. hominis were not agglutinated by anti-phosphatidylglycerol antibodies; but after partial digestion of the membrane proteins with Pronase, the mycoplasmas were heavily agglutinated by the anti-phosphatidylglycerol antibodies. The same amount of anti-phosphatidylglycerol antibodies was bound to intact M. hominis, containing 600 mug of phosphatidylglycerol as to 6 mug of phosphatidylglycerol in the optimal configurational arrangement of a mixed phosphatidylglycerol/phosphatidylcholine/cholesterol micelle. It is concluded that the major part of the phosphatidylglycerol in native M. hominis membranes is masked, probably by membrane proteins, and is not accessible to the anti-phosphatidylglycerol antibodies.
The surface carbohydrate structures on the cell membranes of various mycoplasma species have been investigated by using lectins, which are sugar-specific proteins. Carbohydrate structures presumably bound to glycolipids, with both galactose and glucose units, were found to be exposed on the surface of Mycoplasma pneumoniae and its temperature-sensitive mutants, M. mycoides var. mycoides and capri, M. pulmonis, M. gallinarum, and M. gallisepticum. Lipid-bound glucose was found on M. neurolyticum. The possible relationship of the lipid-bound surface carbohydrate groups to the known serological cross-reactions and lipid compositions of the various mycoplasma species is discussed. Intact Acholeplasma laidlawii and M. fermentans have no lectin-binding sites exposed on their surfaces; galactose groups were discovered only after Pronase digestion of the organisms, suggesting that their glycolipids are hidden under a protein layer. Neither intact nor Pronase-digested M. hominis reacted with the lectins; this is fully consistent with the lipid composition of this organism, which contains glycolipids. The lectins from Vicia cracca and Phaseolus vulgaris, which react with N-acetyl-galactosamine groups, agglutinated M. gallinarum, M. gallisepticum, M. mycoides var. capri, and M. pulmonis. The agglutinability was lost after Pronase treatment, indicating that the corresponding carbohydrates are presumably protein bound. They may be correlated with the extracellular structures observed by electron microscopy of both sectioned and negatively stained mycoplasma species.
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PURPOSE: Quantitative angiographic studies on the vasomotility of epicardial coronary arteries are gaining increasing relevance. We investigated whether radiographic contrast agents might influence coronary vasomotor tone and thereby the results of such studies. METHODS: Coronary angiograms were taken in 12 patients with coronary artery disease at intervals of 5, 3, 2, and 1 min with the low-osmolar, nonionic contrast agent iopamidol 300, and were repeated at identical intervals with the high-osmolar, ionic agent diatrizoate 76%. RESULTS: Quantitative cine film analysis demonstrated no significant diameter changes in angiographically normal and stenotic coronary arteries with iopamidol. With diatrizoate, however, normal segments were dilated 2% +/- 2% (p < 0.01) after 2 min and 10% +/- 3% after the 1 min interval (p < 0.001). Stenoses showed no uniform responses to diatrizoate. CONCLUSION: Low-osmolar, nonionic contrast agents should be preferred for quantitative angiographic studies on epicardial coronary vasomotility. When using ionic contrast agents, injection intervals of at least 3 min are required.
With aging, morphologic organ changes due to arteriosclerosis, hypertension, or diabetes increase, and renal transplantation tends to become less successful. We analyzed the outcome of transplantation in 123 recipients who underwent renal transplantation between January 1988 and December 1989. We assessed patient and graft survival after 1, 5, and 6 years as well as mortality and transplant failure and the incidence of rejections. We compared the results of patients aged under 60 years (group 1, n = 60) with the findings of patients aged over 60 years (group 2, n = 63). Immunosuppression was with cyclosporin A and prednisolone without exception. In patients under the age of 60, the overall patient survival at 1, 5, and 6 years was 97, 95, and 90% and was significantly compromised in recipients over the age of 60 (92, 80, and 75%). The 1-, 5- and 6-year graft survival rates were 92, 90, and 90% in recipients aged over 60 years and 88, 82, and 79% in recipients under the age of 60 years. The incidence of rejection was significantly higher in recipients under the age of 60. Patient mortality was mainly due to cardiovascular complications and transplant failure mainly related to transplant thrombosis. In older patients, renal transplantation is thought to be an option of survival rate improvement in comparison with hemodialysis. The incidence of transplant rejection is significantly lower, and this indicates a promising result regarding the long-term prognosis. As cardiovascular complications present as the main mortality factors of both transplant and patient, the prognosis is considered to be highly dependent on screening and treatment of these risk factors.
The dynamics of aging encompass the topics "aging of society" and "coping with chronic illness". Both are discussed using data from a qualitative study on return to work after coronary artery bypass surgery. Data from the retrospective substudy reveal four forms of aging as biographical development toward early retirement, old-age retirement, or related stages. It emerges that the manner of aging is less influenced by medical rehabilitation or medical history, and more by the patient's occupation and socio-economic status. Case reports are used to show that social class is a facilitation context, but not a determining force, regarding the choice between postoperative retirement or return to work. The final section briefly discusses whether the findings concerning the dynamics of aging of the cohort operated on in the late 1970s apply also to that of the cohort operated on in the late 1980s; this is addressed using some data from the prospective sub-study.
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