Zeitschrift fur klinische Chemie und klinische Biochemie最新文献

Initial experiments on the constant appearance of unesterified fatty acids and hydrocarbons in cereborspinal fluid are presented. With the present method of analysis, these two groups of substances can always be detected in cerebrospinal fluid. The constitution of the unesterified fatty acids as well as the hydrocarbons was determined using gaschromatography linked to mass spectrometry. There is no evidence that the unesterified fatty acids are derived from the blood, or that they are breakdown products of other lipid classes of the cerebrospinal fluid. The origin and significance of the hydrocarbons are not yet known, and remain the subject of further investigations.

A simple potentiometric method for the determination of fluoirde ion in human bones is described. The bone samples were taken from a definite position in the iliac crest. The samples are prepared for analysis by ashing at 550 degrees C, dissolving in HNO3 (4 mol/1) and adjusting the pH with NaOH (4 mol/1) and Total Ion Strength Adjustment Buffer, Absolute values are derived from a calibration curve based on aqueous NaF-buffer solutions. The calibration curve is linear in the range 5.2-10(-3)-1.0-10(-5) mol/1F-. The minimum limit of measurement is 5.2 X 10(-6) mol/1F-. The method has an accuracy of 96.1 % or 92.3% with a series precision based on the Pearson variability coefficient of 1.68%. The normal mass fraction of fluoride in human bones was found to be between 69 and 1740 - 10(-6) F-/ash.

In patients with liver cirrhosis the concentrations of amino acids were measured by ion exchange chromatography in the serum of blood samples taken from various vessels during and after the performance of a porto-caval anastomosis. Statistical evaluation was carried out with a nonparametric test. In three female and eight male patients, amino acids were determined intra operationem in blood samples of the following vessels (n = number of blood samples): arm vein (n = 8), arteria femoralis (n =2), vena cava (n = 7), vena portae (n = p) and aorta abdominalis (n = 5). With exception of ornithine (aorta abdominalis versus vena cava), no statistically significant differences in the concentrations of amino acids were observed in the various blood vessels. One to three years after the introduction of the porto-caval shunt, amino acid concentrations were measured in blood from the arm vein and arteria femoralis in four female and five male patients. The concentrations of glutamic acid, phenylalanine and lysine were significantly higher in blood from the arm vein than in blood of the arteria femoralis. The concentrations of valine, leucine and isoleucine were markedly lower in patients with liver cirrhosis than in normal persons. On the basis of the present findings and of the results obtained with normal subjects, it may be concluded that porto-caval anastomosis does not exert a noticeable effect on the metabolism of amino acids in patients with liver cirrhosis.

The automatic determination of hormone levels in serum by column chromatograhoic methods using a 25 channel peristaltic pump, allows the simultaneous chromatography of 25 samples. The different volumes which are necessary for the successive elution steps are set by the tubing size of the pump and by a preset switch clock. The eluates from the 25 columns are collected simultaneously in fractionated volumes which are also determined in the same electronic clock device. The assays so far adapted to this principle are reviewed: Serum thyroxine (competitive protein binding assay), T3-uptake test (dextran gel filtration), triiodothyronine (radioimmunoassay) and cortisol (competitive protein binding assay or radioimmunoassay). The main advantages of this procedure are increased frequency, improved specificity and standardization at lower costs for these methods. The principle of simultaneous column chromatography appears to be most suited for assays, which require various extraction steps prior to the determination of the hormone, since it allows extraction, specific protein binding and bound/free separation on only one column.

A thin layer chromatographic screening test is reported for the determination of urinary 3-methoxy-4-hydroxyphenylethylene glycol. The concentration in any sample is estimated by visual comparison with a range of 10 standards of different concentrations. The urines of five children with positively diagnosed hormonally active neuroblastoma showed values of 19.0-32.4 mg 3-methoxy-4-hydroxyphenylethylene glycol/g creatinine, whereas control urines contained only 0.4-1.7 mg/g creatinine.

The sensitivity of enzyme kinetic substrate determinations can be improved with the aid of competitive inhibitors. As an example, the determination of glucose dehydrogenase in the presence of potassium thiocyanate is described. The method has the advantage of rapid operation with satisfactory precision.

For the determination of the activity of glutamate: cysteine-gamma-ligase one method was optimized and a new micromethod was developed: a) Utilizing [14C] glutamate and cysteine as substrates, the product [14C] gamma-glutamylcysteine was isolated as its cadmium mercaptide and determined by liquid scintillation counting gamma-glutamyl-[14C] aminobutyrate, which was synthesized from glutamate and [14C] alpha-aminobutyrate was separated from remaining radioactive substrate by paper electrophoresis and counted. Both methods were used to determine the activity of the enzyme in human red blood cells. For 20 parallel determinations a standard deviation of +/- 9% and +/- 5% was obtained for method a and b, respectively. The specific activity of the enzyme in erythrocytes of adults was found to be 0.40 +/- 0.05 U/g hemoglobin with method a, and 0.50 +/- 0.05 U/g hemoglobin with method b.

A new method is described for sampling and sample application in the ultra-trace analysis of air by gas chromatography-mass spectrometry. In this new technique, a preseparation occurs on the gas chromatographic column during sample application, since the atmospheric constituents that are co-condensed during sample application we call this method "Druckaufgabe" (pressure application). The method is not only of theoretical value. It has a potentially wide application to occupational and environmental problems.

A sensitive radioimmunoassay for estimating serum deoxycorticosterone is described which involves descending "overrunning" paper chromatography. An ethanolic paper eluate is used as a solvent for unlabelled deoxycorticosterone in the preparation of the standard curve. The values of the water blanks (7 ng/l) are similar to the sensitivity of the standard curve (5.8 ng/l). The normal mean serum concentration of deoxycorticosterone was found to be 84 +/- 29 ng/l (n = 30) in males and 55 +/- 31 ng/l (n = 35) in females. Serum deoxycorticosterone rose in healthy subjects upon injection of ACTH, after induction of insulin hypoglycemia and after administration of metyrapone, while the rise was absent or blunted in patients with Addison's disease and in patients with pituitary failure.

A simple and rapid method for the estimation of the hydrolysis of succinyl choline by serum cholinesterase variants is described. Succinyl choline, as substrate for the enzyme assay, has many advantages over other substrates (acetyl choline, benzoyl choline and butyryl choline) which have no clinical application. Choline, the hydrolytic product of succinyl choline, is oxidized to betaine aldehyde by choline oxidase (EC 1.1.99.1), a rat liver mitochondrial preparation; this is coupled to the reduction of cytochrome c which is measured at 550 nm. Fifty normal sera (UU), 17 heterozygous (UA) and 8 atypical (AA) were tested with this method, and on the basis of resistance to dibucaine (Cinchocain; Kalow, W. & Genest, K. (1957) Canad. J. Biochem. Physiol. 35, 339-346) inhibition, three distinct groups could be established using succinyl choline as substrate. These results are comparable with the standard optical method of Kalow & Genest (cf. above) using benzoyl choline as substrate.