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M Fuchs

Publications and source records attributed to M Fuchs.

At least 145 records · Page 8Linked to original sources
PubMed1995

Solution-phase immunoassay for determination of cortisol in serum by capillary electrophoresis.

We describe a competitive solution-phase immunoassay for serum cortisol determination that involves capillary electrophoresis (CE) combined with laser-induced fluorescence for separation and quantification. A polyclonal antibody preparation and fluorescein-labeled cortisol are used as assay reagents. 8-Anilino-1-naphthalenesulfonic acid was added to the serum sample during the assay to promote the release of cortisol from endogenous binding proteins. Conditions for the rapid separation of free and bound labeled antigen by CE were developed. Aspects of assay performance are evaluated in this report. The resulting assay protocol allows for the analysis of serum samples without extraction or other sample preparation steps.

Anilino Naphthalenesulfonates↗
PubMed1995

Deoxycholate and cholate modulate the source of cholesterol substrate for bile acid synthesis in the rat.

In the current study, the role of the supply of preformed and newly synthesized cholesterol for the feedback control of the synthesis of different bile acids and the secretion of biliary cholesterol was investigated. To define these cholesterol fluxes and the possibility of a different modulation by bile acids with different suppressive capacities, a continuous labeling with tritiated water was used in rats with an extracorporeal bile duct receiving intraduodenal infusions of taurocholate or taurocholate plus deoxycholate. After bile acid pool depletion (6 to 9 hours) total muricholate, cholate, and chenodeoxycholate synthesis was variably increased (24% to 93%) during an infusion of 304 mumol taurocholate/kg per hour. The increase in bile acid synthesis and biliary cholesterol output was predominantly due to the utilization of preformed (unlabeled) cholesterol. The addition of 52 mumol/kg per hour of deoxycholate to 258 mumol/kg per hour of taurocholate had a comparable effect. In the late period (30 to 54 hours), the taurocholate infusion had little impact on total muricholate and chenodeoxycholate synthesis but caused by a significant increase of the proportion from performed cholesterol. Both total cholate production and its synthesis from de novo (labeled) cholesterol was inhibited by 30% (P < .05) and 64% (P < .01), respectively. The secretion rate of total and de novo biliary cholesterol was higher (65% and 72%; P < .01) compared with controls. In comparison, the combined bile acid infusion led to a further increase of total muricholate synthesis (P < .05), which was again due to an enhanced synthesis from performed cholesterol (P < .001). Similar changes were observed in chenodeoxycholate. The more pronounced suppression of total cholate synthesis by 81% (P < .05) was due to a diminished cholate synthesis from both de novo cholesterol by 72% (P < .001) and preformed cholesterol by 91% (P > .05). We conclude that the modulation of the synthesis of the various primary bile acids in the rat differs and feedback regulation of cholate synthesis by taurocholate and deoxycholate is mediated by different mechanisms of control, including inhibition of cholesterol 7 alpha-hydroxylase, HMG-CoA reductase, and uptake of lipoprotein cholesterol.

Animals↗
PubMed1994

[Not Available].

Historical sociobiographic accounts on members of the scientific and technical professions in the years of the Weimar Republic and after, are as yet scarce. This applied notably to women in the scientific community. Having formally been admitted to academic studies at German Universities only in 1908, their claims of wanting to apply their newly gained knowledge and to pursue academic careers were still not unquestioned by society. The social and cognitive integration of "the female" in male dominated science organisation, especially in the natural sciences and their kin fields in industry, remains problematic to-day. Isolde Hausser, daughter of the ambitious but little succesful inventor-entrepreneur Hermann Ganswindt, took her doctoral degree in physics at Berlin University in 1914, then worked as head of a group at a "Telefunken" laboratory for vacuum tubes till 1929, before she became research scientist at the Kaiser Wilhelm Institute for Medical Research, Heidelberg. There she worked on photoerythemaes and the formation of pigment and discovered the specific action of longwave ultraviolet. She contributed important results to our knowledge on the constitution and the behaviour of organic compounds by modern physical methods. She died of cancer on 5th October 1951.

Academies and Institutes↗
PubMed1994

Disruption of the gene encoding the EcmA, extracellular matrix protein of Dictyostelium alters slug morphology.

The ecmA and ecmB genes of Dictyostelium are expressed in prestalk and stalk cells. They encode components of the slime sheath, the extracellular matrix that surrounds the migrating slug, and the stalk tube, the matrix that encases stalk cells. We have generated, by homologous gene disruption, a mutant in which the ecmB gene is inactivated but the strain develops normally. In contrast, ecmA null mutant strains develop to form abnormally long and thin standing slugs. While the slime sheath of mutant slugs appears to be normal in electron microscopic observations, the sheath material remaining on the substratum after the slug travels through it is abnormally susceptible to breakage. After a short period of migration the axial ratio of mutant slugs decreases to that of normal slugs and, at culmination, normal fruiting bodies are produced. These data suggest that the EcmA protein has its primary role during slug formation, where it contributes to the strength of the slime sheath, and that the function of the EcmB protein is dispensible.

Animals↗
PubMed1994

Source analysis of median nerve and finger stimulated somatosensory evoked potentials: multichannel simultaneous recording of electric and magnetic fields combined with 3D-MR tomography.

At the current state of technology, multichannel simultaneous recording of combined electric potentials and magnetic fields should constitute the most powerful tool for separation and localization of focal brain activity. We performed an explorative study of multichannel simultaneous electric SEPs and magnetically recorded SEFs. MEG only sees tangentially oriented sources, while EEG signals include the entire activity of the brain. These characteristics were found to be very useful in separating multiple sources with overlap of activity in time. The electrically recorded SEPs were adequately modelled by three equivalent dipoles located: (1) in the region of the brainstem, modelling the P14 peak at the scalp, (2) a tangentially oriented dipole, modelling the N20-P20 and N30-P30 peaks, and part of the P45, and (3) a radially oriented dipole, modelling the P22 peak and part of the P45, both located in the region of the somatosensory cortex. Magnetically recorded SEFs were adequately modelled by a single equivalent dipole, modelling the N20-P20 and N30-P30 peaks, located close to the posterior bank of the central sulcus, in area 3b (mean deviation: 3 mm). The tangential sources in the electrical data were located 6 mm on average from the area 3b. MEG and EEG was able to locate the sources of finger stimulated SEFs in accordance with the somatotopic arrangement along the central fissure. A combined analysis demonstrated that MEG can provide constraints to the orientation and location of sources and helps to stabilize the inverse solution in a multiple-source model of the EEG.

Adult↗
PubMed1994

Distribution of parasite cysteine proteinases in lesions of mice infected with Leishmania mexicana amastigotes.

It is well established that Leishmania mexicana amastigotes contain large amounts of cysteine proteinases in their extended lysosomes. In this study it is shown that the cell-free supernatant of homogenized lesion tissue from infected mice contains large amounts of acid proteinases. The majority of this enzymatic activity also corresponds to cysteine proteinases from L. mexicana amastigotes. Immunoelectron microscopy of mouse lesion sections suggests, that frequently amastigotes lyse and release lysosomal cysteine proteinases into the parasitophorous vacuole of infected macrophages. The cysteine proteinases are also found extracellularly in the tissue presumably as a result of macrophage rupture and appear to persist in the lesion tissue, where they may damage host cells and the extracellular matrix.

Amino Acid Sequence↗
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↗