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Biomedical subjects

M Fuchs

Publications and source records attributed to M Fuchs.

At least 163 records · Page 9Linked to original sources
PubMed1994

Surface antigens of Leishmania mexicana amastigotes: characterization of glycoinositol phospholipids and a macrophage-derived glycosphingolipid.

Amastigotes of the protozoan parasite Leishmania proliferate in phagolysosomes of macrophages. They abundantly express glycoinositol phospholipids (GIPLs), which are considered necessary for parasite survival by providing a shield at the surface against lysosomal hydrolases and by serving as receptors for the interaction with host cells. The structures of four GIPLs of L. mexicana amastigotes were characterized by a combination of gas-liquid chromatography-mass spectrometry, methylation linkage analysis and enzymatic treatments. They contain the glycan structures Man alpha 1-3Man alpha 1-4GlcN (iM2), Man alpha 1-6(Man alpha 1-3)Man alpha 1-4GlcN (iM3), Man alpha 1-2Man alpha 1-6(Man alpha 1-3)-Man alpha 1-4GlcN (iM4) and (NH2-CH2CH2-PO4)Man alpha 1-6(Man alpha 1-3)Man alpha 1-4GlcN (EPiM3), which are linked to alkylacyl-phosphatidylinositol. The predominant amastigote GIPL, EPiM3 (approximately 2 x 10(7) molecules/cell), is located at the parasite cell surface, in the flagellar pocket and in lysosomal membranes, but not on host cell structures as shown by immunofluorescence and immunoelectron microscopy. In addition, amastigotes in infected Balb/c mice contain a glycolipid with similar distribution as EPiM3, which has the same characteristics as the Forssman antigen of mammalian cells. In contrast to EPiM3, there is strong evidence that this glycosphingolipid is not synthesized by amastigotes but by macrophages in the lesion. This suggests a mechanism of lipid transfer from the macrophage to the parasite.

Animals↗
PubMed1994

Opening wedge osteotomy for malunion of the distal radius with neuropathy. 13 cases followed for 6 (1-11) years.

13 patients with malunion of the distal radius after Colles' fractures and electroneurographically verified median nerve compression underwent an opening wedge osteotomy without a simultaneous release of the transverse carpal ligament. 12 patients had reduction of the typical night pain with normal or almost normal sensibility within the first 2 months. In 1 patient a release of the carpal ligament was necessary after 6 months. 6 years postoperatively all patients had acceptable wrist function with normal function of the median nerve in all but one.

Adult↗
PubMed1994

Amino acid metabolism by hepatocytes in a hybrid liver support bioreactor.

The amino acid patterns of medium perfusate in a liver cell bioreactor developed for a hybrid liver support system have been measured. There were considerable changes in the concentrations of glutamic acid, glutamine, alanine, arginine, ornithine and branched chain amino acids during the first 10 days which is indicative of dynamic cellular metabolism. From day 15, steady state conditions of nitrogen metabolism are reflected by stable amino acid turnover. Monitoring of urea, K+, and P-450 activity suggests that hepatocytes have switched to a stable protein synthesis with a general amino acid uptake and keto acid release following cell volume increase.

Amino Acids↗
PubMed1994

Alpha-keto acid metabolism by hepatocytes cultured in a hybrid liver support bioreactor.

Isolated pig liver cells cultured using a perfusion technique were analyzed over 39 days to test their ability to change the perfusate alpha-keto acid profile. While the pyruvate concentration in the culture medium decreased as of the first day, the alpha-ketoglutarate (KG), alpha-ketoisocaproate (KIC), alpha-ketoisovalerate (KIV) and alpha-keto-beta-methyl-n-valerate (KMV) were synthesized immediately and released by the liver cells. The metabolic capacity of the cell culture system increased up to day 10, decreased during the following 5 days and reached a steady state beyond day 15, which was maintained for at least 30 days. The branched chain alpha-keto acid release, in particular alpha-ketoisocaproate, reflects an effective transamination capacity of the newly developed culture system and shows an intact protein biosynthesis for at least 30 days in vitro.

Animals↗
PubMed1994

Biliary cholesterol secretion and bile acid formation in the hamster: the role of newly synthesized cholesterol.

In order to define the source of cholesterol for bile acid synthesis and biliary cholesterol, hamsters with an extracorporeal bile duct received an intraperitoneal bolus of [3H]water labeling newly synthesized cholesterol. Thereafter the enterohepatic circulation was interrupted and a nutrient solution was infused during the experimental period of 78 h. In a separate group, pravastatin was administered (54-78 h) to allow discrimination of 3H-labeled cholesterol recycling from plasma and newly synthesized hepatic cholesterol late during the experiment. In controls, newly synthesized biliary cholesterol and primary bile acids derived from cholesterol newly synthesized during the experiment amounted to 5% and 12% immediately after depletion of the bile acid pool (6-9 h), respectively. After longterm bile diversion these proportions increased to 56-63%, whereas 71% of plasma cholesterol was labeled. Pravastatin inhibited the secretion of biliary cholesterol, cholate, and chenodeoxycholate by 30, 50, and 44%, respectively. In contrast, the preinfusion tritium label was suppressed by a maximum of 16%, 14%, and 26%, respectively, reflecting the contribution of cholesterol newly synthesized in the hepatocyte as opposed to labeled cholesterol recycling from the plasma. It is concluded that in the hamster newly synthesized cholesterol is of minor importance as substrate for bile acid synthesis as well as biliary cholesterol, both under near physiologic conditions and after long-term bile diversion. Moreover, the hepatic cholesterol pools subserving the synthesis of the primary bile acids are identical but appear to be different from that of biliary cholesterol directly after the depletion of the enterohepatic bile acids.

Animals↗
PubMed1993

[DNA flow cytometry of malignant melanoma of the choroid].

Thirty-five choroidal melanomas were analyzed by flow cytometry. DNA euploidy, aneuploidy and polyploidy were found in approximately 54, approximately 46, and approximately 20% of the tumors, respectively. No correlation between histological type and ploidy was found. The synthesis phase was irregular in approximately 25 and approximately 38% of the spindle and the mixed cell melanomas, respectively. The G2M peak was broadened in approximately 50% and in approximately 23% of the spindle and the mixed cell melanomas. About 20% of the malignant melanomas were highly proliferative. In 25% of the melanomas chemotherapy seemed to be useful.

Brachytherapy↗
PubMed1993

[Corrective interventions for malunited fractures of the distal end of the forearm. Indications, choice of procedure, results].

Malunion, non-union, as well as painful ligamentous joint instability following fractures to the distal forearm may seriously compromise the function of a hand. Forty-seven surgically treated cases, thirty-nine of which were followed up, are presented in order to point out the problems of such lesions. Retrospective evaluation of the lesion is absolutely mandatory, as it often dates back to childhood. Management should take clinical findings as well as the patient's functional demands on his hands into consideration, but without overestimating therapeutic potentials.

Adolescent↗
PubMed1993

Post-capillary Immobilon-P membrane fraction collection for capillary electrophoresis.

A simple, cost-effective and efficient method of continuous fraction collection for capillary electrophoresis is described. The method employs a membrane, such as polyvinylidene difluoride, onto which the separated components from a capillary electrophoresis capillary are directly collected to overcome the problem of analyte dilution and to facilitate the fraction collection process. Model proteins are separated and collected onto a polyvinylidene difluoride membrane.

Animals↗
PubMed1993

Bile acid synthesis from newly synthesized vs. preformed cholesterol precursor pools in the rat.

The present study defines the origin of cholesterol subserving bile acid synthesis in male rats with an extracorporal bile duct by labeling newly formed cholesterol with tritiated water. Within 6 hr after interruption of the enterohepatic circulation, the bile acid pool was depleted. At this early time point the proportion from de novo cholesterol was 8% and 12% for biliary cholesterol and cholate, but 18% and 19% for muricholate and chenodeoxycholate, respectively. This proportion gradually rose to 40%, 34%, 51% and 51%, respectively, at 15 to 30 hr. At 78 hr after bile diversion, 64% of cholate was labeled, compared with 84% to 88% of the other biliary lipids and 71% of plasma cholesterol. Total and labeled bile acid secretion exhibited the same diurnal rhythm. To allow differentiation between direct hepatocytic de novo synthesis of bile acids from acetate and recycling of labeled plasma cholesterol, an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (pravastatin) was infused from 54 to 78 hr. It suppressed total synthesis of primary bile acids by 60% to 80% but decreased the tritium label of bile acids only from a range of 74% to 92% (54 hr) to a range of 54% to 63% (78 hr), which was in the range of plasma cholesterol (58%). We conclude that bile acids and biliary cholesterol are synthesized mostly from preformed (i.e., plasma) cholesterol, both immediately after depletion of the pool in enterohepatic circulation and after derepression. Moreover, the hepatic cholesterol pools subserving the synthesis of different bile acids and biliary cholesterol secretion are not identical.

Acetates↗
PubMed1992

Effect of the signal-to-noise ratio on the quality of linear estimation reconstructions of distributed current sources.

Currently, linear estimation reconstruction is the only feasible method for extracting information about spatially distributed current sources from measurements of neural magnetic fields. We present the results of a systematic study of the effect of the signal-to-noise ratio on the imaging quality of one such algorithm in over-as well as undetermined circumstances. In particular, we will discuss the necessary trade-off between the contradictory goals of a minimum norm of the reconstructed current density distribution and of a minimal deviation of the reconstructed fields from the measured fields. As an example, we show the reconstruction of a simple arrangement of two nearly parallel dipoles in two different depths inside a spherical volume conductor, discussing the differences between the computer simulation without noise and simulation with a realistic noise level.

Algorithms↗
PubMed1992

[Results of a volar approach to plate osteosynthesis of radius shaft fractures. Theoretical basis--clinical results].

This retrospective study analyses the results of 80 shaft fractures of the radius treated by open reduction and plating by a volar approach. Studies about strain distribution on the radius shaft worked out a varying pattern of tensile forces and a continuously change of the tension bend side through full range of motion. So from the biomechanical aspect an ideal position for compression plating is not determined and dorsal or volar plating brings the same stability. The advantage of the volar approach by Henry is the possibility of an easy extension of the approach to the distal or proximal part of the forearm and an optimal covering of the plate by soft tissue. To expose the superficial radial nerve is obligate, if necessary the deep radial nerve should be exposed too in proximal fractures. From 1973 to 1987 80 fractures of the shaft of the radius were treated by plating using the volar approach, since 1977 3.5 dynamic compression plate of the AO was used exclusively. Only two non-unions occurred in the beginning when the AO's third tube plate was used routinely. One massive callus formation had to be noticed with a complete loss of pronation and supination. One infection occurred, but normal wound healing and bone union could be achieved after early reoperation. Two incomplete lesions of the superficial radial nerve were seen, but normal sensibility occurred spontaneously. No other neural or vascular complication had to be noticed using this approach. In the follow-up 56 patients were seen two to 14 years postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Replication of grapevine fanleaf virus satellite RNA transcripts in Chenopodium quinoa protoplasts.

A set of full-length cDNA clones of the satellite RNA of grapevine fanleaf nepovirus isolate F13 (GFLV-F13) was constructed with a variable number of additional, non-viral nucleotides at the 5' and 3' ends. The biological activity of the RNAs transcribed from these constructs was tested in Chenopodium quinoa protoplasts using a helper virus. When inoculated with arabis mosaic virus S (ArMV-S) RNA as helper, transcripts with 33 non-viral nucleotides at the 5' end (tr45p4) did not replicate, whereas transcripts with only one non-viral nucleotide at the 5' end (tr3S and tr3M) did replicate. Capping of the transcripts enhanced their replication. On the other hand, the presence of extra nucleotides at the 3' end had little influence on the biological activity of the in vitro transcripts. In contrast with ArMV-S, GFLV isolate 24 was not a helper for tr3M transcripts, indicating a specific interaction between the helper strain and the satellite RNA.

Base Sequence↗