Zeitschrift fur klinische Chemie und klinische Biochemie最新文献

A simple modification of the atomic absorption method for the determination of serum copper is described, with deproteinization but without incubation at 90 degrees C. The method is characterized by high precision and accuracy, and it is linear throughout the clinically important range.

Because of the difficulties in drawing blood for clinical chemistry in small laboratory animals there exist many methods for sampling blood and the preparation of serum, none of which is generally accepted or well standardised. It was the aim of this study to investigate the effects of sampling techniques on normal values of enzyme activities in the serum of rat and mouse. The activities of the following enzymes were determined: sorbitol dehydrogenase, lactate dehydrogenase, malate dehydrogenase, glutamate dehydrogenase, aspartate aminotransferase, alanine aminotransferase, pyruvate kinase, creatine kinase, myokinase, alkaline phosphatase and leucine aminopeptidase. In addition plasmaproteins, urea and inorganic phosphorus were measured. In rats blood was obtained from the following sites: retroorbital venous plexus, jugular vein, heart and ventral aorta. In mice blood was sampled from the jugular vein and the ventral aorta. Shifts of water from the interstitial to the intravascular space due to hypovolemia occurring during the experimental procedure were followed up by measuring the hematocrit and the distribution of radioiodide labelled albumin. In rats the activities of lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase, pyruvate kinase, creatine kinase and myokinase found in blood serum obtained from the retroorbital venous plexus and the ventral aorta were too high compared to the other sampling sites. Activities of alkaline phosphatase and alanine aminotransferase were slightly elevated when blood was sampled from the punctured retroorbital venous plexus. Small differences in plasmaproteins and hematocrit values were found to be due to acute shifts of water within the extracellular space. In mice the activities of lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and myokinase were found to be too high in blood serum obtained from the ventral aorta. Efflux of enzymes from damaged cells and the interstitial space ive caused erroneous results too, but only to a minor extent. The most reliable method for blood sampling in rat and mouse is the cannulation of the jugular vein. The heart puncture can be recommended too. Attention should be paid, however, to the possibility of aspirating disrupted muscle cells through the inserted needle.

Clinical chemical analyses are carried out in many animal experiments performed for medicinal research. For the evaluation of the analytical results fundamentals which have been tried tested and proven in human medicine are still frequently missing, such as reliability criteria, reference values, condition of specimen collecting and the knowledge of other important influences. The workshop conference of the German Society for Clinical Chemistry therefore prepared an inventory, and the most important problems were discussed with examples; guide-lines were worked out for planning, performance and evaluation of clinical chemical investigations on laboratory animals.

Extensive re-investigations with regard to the molar extinction coefficients of NADH and NADPH proved that in future, calculations in routine work can be performed with the following much more accurate epsilon-values: 6.15 x 10(3) 1 x mol-1 x cm-1 at Hg 334 nm (NADH and NADPH), 6.3 X 10(3) 1 X mol-1 x cm-1 at 340 nm (NADH and NADPH), 3.4 X 10(3) 1 X mol-1 X Cm-1 (NADH) and 3.5 x 10(3) 1 x mol-1 x cm-1 (NADPH) at Hg 365 nm, respectively. The safest measurement is performed at Hg 334 nm, because here epsilon is identical for both coenzymes and deviations of the epsilon-value caused by temperature, pH and ionic strength are less than 0.5%.

The enzymic determination of total cholesterol described by P. Röschlau (Z. Klin. Chem. Klin. Biochem. 12, 403-407 (1974)) was modified and adapted to the Centrifichem system. The method which requires only 5 mul serum, is accurate, quick and simple. A separate serum blank is not necessary. Compared with the manual method, smaller quantities of reagents used and the resulting decrease in cost are appreciable for large series of analyses. The course of the reaction at 30 and 37 degrees C, the linearity, calibration, precision, recovery, and correlation with the Lieberman-Burchard method and the enzymic manual method are described.

Studies on the individual components of the renin-angiotensin-aldosterone system are of crucial importance for the investigation of hypertension. The purpose of the workship conference was to give occasion for discussion amongst German speaking research groups on the determination of the individual components of this system, and for the consideration of new results and their pathophysiological significance, as well as possibilities for the evaluation of radioimmunological data with the aid of electronic data processing. The following report is a summary of the contributions to the discussion by those taking part in the workshop conference.

Alkaline phosphatase (EC 3.1.3.1) in extracts of human feces resembles alkaline phosphatase in extracts of duodenal mucosa, except for its electrophoretic mobility in starch gel. It is very probable that the normal feces alkaline phosphatase derives from intestinal mucosa. Gall bladder alkaline phosphatase, which is markedly different, has not been found in normal feces. Some patients with acute viral hepatitis or protozoasis excrete an alkaline phosphatase which resembles gall bladder alkaline phosphatase and has the characteristics of 5'-nucleotidase (EC 3.1.3.5). The appearance of this enzyme correlates with low total alkaline phosphatase activity of the excreta.

Bilirubin may cause haemolysis of red cells, especially in the presence of light. The possible dependence of this effect on the metabolic state of the cells has been investigated. For this purpose erythrocytes were stored up to five days to deplete the concentration of ATP. Every day a constant amount of bilirubin was added to the cells. On third day of storage bilirubin induced haemolysis, which was aggravated rapidly during further storage. Bilirubin-induced haemolysis could be reduced after increasing the ATP levels by incubation of the red cells with inosine.