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Biomedical subjects

H Mattenheimer

Publications and source records attributed to H Mattenheimer.

At least 19 recordsLinked to original sources
PubMed1990

A multicenter evaluation of the Boehringer Mannheim/Hitachi 717 system.

Analytical performance of the Boehringer Mannheim/Hitachi 717 system was evaluated in a multicenter study involving seven different laboratories. Fifty-five methods including end point chemistries, enzymes, ISE, TDM, DAU, and specific protein assays were assessed over a 7 month period. Methods on the analyzer exhibited excellent precision with CVs less than 2% for within run precision, and CVs less than 3% for between day precision for most analytes; linearity, which met or exceeded manufacturer's claims; minimal sample and reagent carryover, and no significant interference from hemolysis; icterus; and lipemia. Recovery of the assigned value for 10 analytes in SRM 909 was acceptable. Comparison of methods with other BM/Hitachi analyzers resulted in slopes close to unity (0.93-1.06); comparison to other clinical chemistry analyzers yielded slopes of 0.88-1.07. Excellent performance and diverse method applications make the BM/Hitachi 717 analyzer a suitable instrument for work station consolidation.

Calibration↗
PubMed1988

Recommendation for the measurement of "alanine aminopeptidase" in urine.

A method is recommended for the measurement of the catalytic concentration of alanine aminopeptidase in the urine of man, rat, and dog, using L-alanine-4-nitroanilide as substrate. In currently used methods, substrate concentrations between 1.7 and 2.0 mmol/l are used. Kinetic experiments show, however, that the reaction is inhibited by substrate concentrations exceeding 0.8 (man), 0.3 (rat) and 0.5 mmol/l (dog); these concentrations lie in the range of the Km values. Assay conditions were therefore chosen to give the lowest possible Km. The Km value depends on the type of buffer, and it increases with pH and temperature. The recommended assay conditions are: triethanolamine buffer 70 mmol/l, pH 7.6; L-alanine-4-nitroanilide concentrations depending on the species; incubation temperature 25 degrees C.

Aminopeptidases↗
PubMed1986

Identification of inhibitors of urinary alanine aminopeptidase.

Amino acids and ammonia were identified as natural inhibitors of urinary AAP. In urines from healthy volunteers approximately one half of the inhibition could be accounted for by amino acids and ammonia. At the measured concentrations, histidine, ammonia and phenylalanine, in decreasing order, were the most effective inhibitors. Results from kinetic studies with amino acids added to gel-filtered urine are consistent with the presence of two AAP isoenzymes with different inhibition characteristics. The ten amino acids which were tested show the same inhibition kinetics. Differences between amino acids are quantitative.

Amino Acids↗
PubMed1985

Enzymuria of the rat: biorhythms and sex differences.

Alanine aminopeptidase, gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase were measured daily over 65 days in 24-hour urine of male and female Wistar rats. The mathematical evaluation was based on the Fourier-analysis. The excretion of alanine aminopeptidase and gamma-glutamyltransferase was higher in male than in female rats. This sex-dependent difference was not observed for N-acetyl-beta-D-glucosaminidase. The excretion of the 3 enzymes followed a biorhythm with a dominant period of 7 days for gamma-glutamyltransferase and N-acetyl-beta-D-glucosaminidase and one of 9 days for alanine aminopeptidase. Biorhythms and sex differences of enzymuria should be considered in experimental designs.

Acetylglucosaminidase↗
PubMed1983

Enzymuria of the rat: the preparation of urine for enzyme analysis.

The effects of sample preparations by dialysis and gel filtration on the catalytic concentrations of alanine aminopeptidase, N-acetyl-beta-D-glucosaminidase, and beta-glucuronidase are described. Individual urines were collected during 24 hours on 3 consecutive days from 10 male rats. Gel filtration (Sephadex G25) was more effective than dialysis against water in the removal of inhibitors of N-acetyl-beta-D-glucosaminidase and beta-glucuronidase. For alanine aminopeptidase, slightly higher results were obtained by dialysis. Inhibitor contents varied from day to day. Activity decreases of beta-glucuronidase and N-acetyl-beta-D-glucosaminidase were found in some of the urine samples and interpreted as removal of activators. Gel filtration is recommended for the preparation of rat urine for the measurement of these three enzymes. The slightly inferior effect of gel filtration on alanine aminopeptidase should be disregarded for the sake of practicality.

Acetylglucosaminidase↗
PubMed1976

[The feigned release of cell enzymes. Distribution and transport of cell enzymes within the extracellular space. I (author's transl)].

A sudden increase of enzyme activities in plasma is not necessarily due to a release of enzymes from damaged cells. Three experimental models were used to demonstrate that acute alterations of enzyme activities, as much as +/- 15%, can be caused by fluid-shifts between the intra- and extravascular compartments. Venous occlusion of the forearm by tourniquet produces an increase of the intravascular hydrostatic pressure and subsequently results in a decrease of the plasma volume distal to the tourniquet. Because enzyme molecules are not freely diffusible across the capillary membrane the enzymatic activity increases proportionally to the decrease of plasma volume. Changes in the body posture are accompanied by changes in plasma volume and similarly by alterations in the concentration of plasma-proteins and by alterations in intravascular enzyme activities. Increased enzyme activities in plasma during strenuous physical effort are due chiefly to a concentration of macromolecules within the intravascular space because of a decrease in plasma volume and not to a release of enzymes from hypoxic muscle cells. During recovery after termination of the exercise there is a second and longer lasting increase in enzyme activities in plasma which could be related to a release of enzymes from injured cells. It is suggested that some of these changes could be due to an increase in lymph flow and thereby an increasing transport of enzymes from the interstitial to the intravascular compartment.

Biological Transport↗
PubMed1976

[Cell enzymes in lymph. Distribution and transport of cell enzymes within the extracellular space. II (author's transl)].

Enzyme patterns were measured in the lymph of the thoracic duct of the dog and in the intestinal lymph of the rat. Those patterns were compared to the corresponding activities in blood plasma. From the results it is concluded that under physiological conditions cell enzymes are released into the interstitial space and from there are transported via the lymph into the intravascular space. Only enzymes with a low molecular weight such as myokinase are able to penetrate the capillary membrane, thereby reaching the plasma without being transported exclusively by the lymph. There is a close relationship between the molecular weight of enzymes and their plasma/lymph ratios. In the rat the enzyme patterns in mesenteric lymph nodes and in intestinal mucosa and muscularis (duodenum as well as ileum) were also determined. No direct correlation between those intracellular patterns and the enzyme patterns in the intestinal lymph could be established. The significance of lymph and lymph flow for clinical enzymology is discussed with respect to physiological and pathological conditions. High sensitivity of diagnosis by means of enzyme measurements in plasma can be achieved only if the capillary permeability in the injured organ is high and/or the lymph flow from the organ is not restricted by the injury.

Animals↗
PubMed1975

Acute myocardial infarction diagnosed by myoglobinuria.

Myoglobin can be found in excess in the urines of some patients with acute myocardial infarction. To test the specificity of this finding, urine specimens were analyzed from 39 patients with provisional diagnosis of myocardial infarction by means of a hemagglutination-inhibition technique with prepared antisera to monkey myoglobin. Of 24 patients with subsequently documented myocardial infarction, 15 had at least one positive determination. None of the 15 patients without infarction had positive tests. Ten of 13 patients with infarction studied within 24 hours of the initial event had positive reactions. The percentage of positive reactions in the infarct group decreased sharply after the first 24 hours. This technique may be of value in rapid screening of patients with possible acute myocardial infarction during early stage of symptoms.

Aspartate Aminotransferases↗