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Biomedical subjects

E Schleicher

Publications and source records attributed to E Schleicher.

At least 73 records · Page 4Linked to original sources
PubMed1985

Different effects of reductive and nonreductive glucosylation on LDL-catabolism.

The effects of various degrees of reductive and nonreductive glucosylation of low density lipoprotein on its catabolism by human fibroblasts have been examined. Moderate glucosylation of LDL does not alter its interaction with the high affinity receptor at concentrations of 5-2000 micrograms LDL-cholesterol/ml. Only heavy glucosylation of LDL (more than 12 lysine residues glucosylated per apo B), i.e. conditions not expected to occur in diabetes, slows receptor-mediated internalisation and degradation. In contrast, impairment of LDL-catabolism has been found at even low degrees of reductive glucosylation. The possible reasons for the different properties of reductively and nonreductively glucosylated LDL are discussed.

Fibroblasts↗
PubMed1984

Changes of human glomerular basement membrane in diabetes mellitus.

Glomerular basement membranes were isolated from kidneys of human diabetics and non-diabetics. Albumin and immunoglobulin G content of glomerular basement membranes as determined after protease digest was higher in the diabetic group while lower values were obtained for heparan sulphate. Nonenzymatic glucosylation of whole glomerular basement membranes and tendon tissue was significantly elevated in diabetic subjects. Correlation of the determined parameters suggest that charge and size selective properties are altered in diabetic glomeruli. Serum albumin and albumin deposited in glomerular basement membranes showed the same content of nonenzymatically bound glucose in a normal and in a diabetic subject, respectively. Thus it would appear that in human diabetes the glucosylated albumin does not underly increased transcapillary transport as was reported in vitro.

Adult↗
PubMed1983

Studies on the interference by haemoglobin in the determination of bilirubin.

Haemoglobin interference in the determination of bilirubin was compared in 7 different methods using the Jendrassik-Grof procedure, the Jendrassik-Grof-Nosslin modification, and the more recent procedures using nitrophenyldiazonium, 2,5-dichlorophenyldiazonium, 2,4-dichloraniline, and a direct reading method. To a variable degree, haemoglobin decreased the apparent absorption of the reaction product in all procedures. The extent of this decrease depended on the reagent used, the wavelength, incubation time, bilirubin concentration and the type of blank used. In an attempt to elucidate the mechanism of interference, haemoglobin was found to destroy the bilirubin diazo-compound whereas haemoglobin was ineffective. Likewise, storage of haemolytic samples for several days led to a disappearance of haemoglobin. H2O2, which had no effect in the absence of haemoglobin, potentiated the action of haemoglobin on diazobilirubin coupling. From our observations it can be concluded that haemoglobin disturbs the diazo-bilirubin reaction by a dual mechanism. H2O2, formed from oxyhaemoglobin by autoxidation, destroys the diazo bilirubin colour. In accordance with this explanation, potassium iodide stabilized the diazo compound against the peroxidative effect of oxyhaemoglobin; stabilization was not effective with superoxide dismutase, mannitol or ascorbate.

Bilirubin↗
PubMed1982

Comparison of two methods for very low density and low density lipoprotein cholesterol determination.

It is shown that VLDL-cholesterol cannot be calculated from serum triacylglycerol at elevated triacylglycerol concentrations (above 2 g/l). Using the method of Friedewald et al. ((1972) Clin. Chem. 18,499-502), VLDL-cholesterol is usually overestimated in these sera and, consequently, LDL-cholesterol underestimated. Quantitative lipoprotein electrophoresis according to Wieland & Seidel ((1979) Innere Medizin 5,290-300), on the other hand, yields VLDL-cholesterol values which correspond to ultracentrifugation data within narrow limits, even in sera with high triacylglycerol contents. A nomogram has been developed for the evaluation of electropherogram.

Chemical Precipitation↗
PubMed1981

Specific quantitation by HPLC of protein (lysine) bound glucose in human serum albumin and other glycosylated proteins.

A specific and sensitive method for quantification of the fructose-lysine linkages present in non-enzymatically glycosylated albumin and other proteins is described. Protein is hydrolyzed for 18 h in 6 mol/l HCl at 95 degrees C to yield furosine (epsilon-N-(2-furoylmethyl)-L-lysine) known as a specific degradation product of fructose-lysine. Furosine is then separated on HPLC and quantified by its UV-absorbance against a prepared fructose-lysine standard. The method has been successfully used for the determination of glycosyl-albumin in diabetic patients starting from 100 microliter serum or less, as well as for various other proteins. Unlike the usually employed thiobarbituric acid assay the present procedure is truly specific for the detection of ketoamine linkages of glycosylated proteins.

Blood Glucose↗
PubMed1980

Utilization of (E)-2-butenoate (crotonate) by Clostridium kluyveri and some other Clostridium species.

Clostridium La 1 obtained from a Clostridium kluyveri culture was compared with a typical C. kluyvery strain (DSM 555). The former grows on cortonate and is unable to use ethanol-acetate as carbon sources. The latter grows on crotonate only after long adaptation periods. Resting cells of both strains show also pronounced differences in the fermentation of crotonate. This holds even for C. kluyveri grown on crotonate. Besides several other differences the most striking is that there is no hybridization between the DNA of both strains. Crotonate seems not to be a very special carbon source since C. butyricum and C. pasteurianum grow on crotonate medium supplemented by peptone and yeast extract.

Acetates↗
PubMed1978

Stereochemistry and mechanism of reactions catalyzed by tryptophanase Escherichia coli.

Several beta replacement and alpha,beta elimination reactions catalyzed by tryptophanase from Escherichia coli are shown to proceed stereospecifically with retention of configuration. These conversions include synthesis of tryptophan from (2S,3R)- and (2s,3s)-[3(-3H)]serine in the presence of indole, deamination of these serines in D2O to pyruvate and ammonia, and cleavage of (2S,3R)-and (2S,3S)-[3(-3H)]tryptophan in D2O to indole, pyruvate, and ammonia. A coupled reaction with lactate dehydrogenase was used to trap the stereospecifically labeled [3-H,2H,3H]pryuvates as lactate, which was oxidized to acetate for chirality analysis of the methyl group. During deamination of tryptophan there is significant intramolecular transfer of the alpha proton of the amino acid to C-3 of indole. To determine the exposed face of the cofactor.substrate complex on the enzyme surface and to analyze its conformational orientation, sodium boro[3H]hydride was used to reduce tryptophanase-bound alaninepyridoxal phosphate Schiff's base. Degradation of the resulting pyridoxylalanine to (2S)-[2(-3H)]alanine and (4'S)-[4'(-3H)]pyridoxamine demonstrates that reduction occurs from the exposed si face at C-4' of the complex and that the ketimine double bond is trans.

Carbon Radioisotopes↗
PubMed1978

Evaluation of the Bradford method for protein determination in body fluids.

The applicability of a dye binding method for protein determination described by Bradford (1976), Anal. Biochem. 72, 248--254) for use in the clinical chemical laboratory was studied. The simple, fast and sensitive method is well suitable for protein determination of cerebrospinal fluid but not for urinary protein. Polymer carbohydrates (Macrodex) do not interfere with dye binding.

Blood Proteins↗
PubMed1977

Stereochemistry of methylene transfer involving 5,10-methylenetetrahydrofolate.

The stereochemistry of the transfer catalyzed by rabbit liver serine transhydroxymethylase (EC 2.1.2.1) of the prochiral hydroxymethyl group from serine to tetrahydrofolate to form 5,10-methylenetetrahydrofolate was studied. Initial kinetic studies on labeled 5,10-methylenetetrahydrofolate showed that nonenzymatic racemization of the prochiral methylene center was buffer dependent and was slow under the conditions employed. Specifically tritiated (3R)- and (3S)-serines were employed to study the transfer reaction. Reactions were carried out under various conditions and the stereochemistry of the methylene carbon of the 5,10-methylenetetrahydrofolate produced was determined. The enzyme was shown to be partially stereospecific for this transfer reaction, proceeding with a loss of about 50% of the stereochemical purity of the transferred carbon center. Possible mechanistic interpretations of this finding are discussed.

Animals↗
PubMed1977

[Piprozoline in clinical trials (author's transl)].

The tolerance and efficacy of ethyl (Z)-(3-ethyl-4-oxo-5-piperidino-thiazolidin-2-ylidene) acetate (piprozoline, Gö 919, Problin) were investigated in open and controlled clinical trials involving a total of 1545 patients and 1807 courses of therapy. The objective of this paper is to compare the experimental findings, some of which have already been published, with the results of the extensive clinical investigations. Despite the well-known problems associated with obtaining precise data on upper abdominal disorders, the evaluation of the available comprehensive clinical data has shown that probiline possesses definite therapeutic benefits confirming the experimental findings. Individual complaints such as bloating, upper abdominal pressure, meteorism and flatulence, nausea and vomiting, constipation, anorexia, and fat intolerance improved significantly under probiline therapy. Taking all the criteria into consideration, the overall results of the studies with probiline versus placebo in patients with gall-bladder diseases and intestinal disorders have proved that this choleretic substance is of therapeutic benefit. Serum bilirubin and alkaline phosphatase showed a significantly greater tendency to return to normal levels under probiline therapy than with placebo. The majority of conditions treated were of biliary origin. Aside from establishing the drug's therapeutic profile, the data published also show that the rate of side-effects was insignificant.

Adolescent↗
PubMed1976

Stereochemistry of the formation of cysteine by O-acetylserine sulfhydrase.

The enzymatic preparation of (2S, 3R)- and (2S, 3S)-[3-3H] serine from the corresponding stereospecifically tritiated 3-P-glycerates is described. Following conversion into T-acetylserine, these substrates were used to establish the steric course of the O-acetylserine sulfhydrase reaction. The two samples of cysteine formed in this reaction were analyzed for their configuration at C-3. The results indicate that the replacement of the acetoxy by a sulfhydryl group in the O-acetylserine sulfhydrase reaction occurs with retention of configuration at carbon atom 3.

Cysteine↗