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D Duchassaing

Publications and source records attributed to D Duchassaing.

9 recordsLinked to original sources
PubMed1991

[Update of a selected technique for uric acid determination in plasma and serum. Experimental study and value of derivative spectrophotometry].

A critical study of the candidate reference method for evaluation of uric acid in plasma proposed by the American Association of Clinical Chemistry is followed by testing in six laboratories. The dispersion of results is wide (CV greater than 5%). The importance of turbidity remaining after the deproteinization by trichloracetic acid is clearly demonstrated. This turbidity is really not reproducible from an operation to another one on the same serum. It is very likely responsible of the great dispersion of the results. After that, other deproteinization methods are tried. Ultrafiltration and ultracentrifugation give both defect errors because uric acid is in part bound to proteins. So it is necessary to find another technic which cancels the effects of turbidity on the absorbance readings in the ultra-violet domain. Experimental studies showed that uric acid may be evaluated with a good accuracy by derivative spectrophotometry, in lipid solutions as well as in cloudy ones. Turbidity was created by intralipid suspension additions. Various parameters hitting the method were examined (linearity, smoothing window...), taking as criterion the measure of overloaded serums at different levels. At last, the method is successfully transferred in several sites. In the case of blood serum, the respective influences of derivation and of repetition of final centrifugations are studied in order to estimate the effect of remaining turbidity. By the use of derivative spectrophotometry the improvement of the method of evaluation of uric acid proposed by A.A.C.C. is very noticeable; it reduces the variation coefficient between sites to less than 2%.

Animals↗
PubMed1989

[A recommended method for determination of uric acid in serum].

SFBC work group on uric acid propose a method for evaluation in blood serum which is modeled on the one defined by American Association for Clinical Chemistry. Serum is deproteinized by trichoracetic acid and the supernatant, buffered to pH 8.5, is submitted to uricase action. The disappearing of the strong band of uric acid in UV is measured by derivative spectrophotometry; this procedure vanished the effect of trouble which remains in the supernatant. This spectrophotometric technic permit to reach, in multiple sites, a variation coefficient near of 1 p. cent.

Analysis of Variance↗
PubMed1979

[Clinical and biological aspects of macroamylasemia (author's transl)].

The authors report a case of macroamylasemia in which the diagnosis was made with some difficulty. A hyperamylasemia was discovered after the patient, an alcoholic, had been hospitalized for atypical abdominal pain and weight loss, and this was thought to be due to an acute episode of chronic pancreatitis. The absence of an incrase in amylasuria suggested the presence of a macroamylasemia, and both diagnoses were confirmed by suitable exploratory investigations. Alcoholic cirrhosis was also present. The two main known types of macroamylase and their iatrogenic variant are described as well as the incidence of this biological anomaly in the general population. Confirming the presence of this anomaly in the plasma is a delicate and complex procedure. Simultaneous study of amylase-creatinine clearance ratio was thought to be a decisive test, but this does not appear to be true.

Amylases↗
PubMed1979

[In vitro and in vivo stability of macroamylase (author's transl)].

A complex case of macroamylasemia in an alcoholic subject with chronic pancreatitis is presented here. The existence of a macroamylase, suggested by hyperamylasemia associated with low amylasuria and by values of the ratio amylase clearance/creatinine clearance lower than 1%, was confirmed by the profile of the amylase activity after filtration on gel of the patient's serum. The macroamylase activity of samples taken at various times over a period of seven months presents a variable characteristic: lowered at the beginning of the fourth month, it rose suddenly following a portal systemic encephalopathy, then became nil a fortnight later. This oscillating character found during the following months is not associated with the values of the serum amylase. The subject's pancreatic juice had no macroamylasic activity but the pancreatic amylase, in vitro, may be feebly linked to a constituant of the patient's serum. The nature of the protein associated with the amylase was not discovered. To in vivo variations of the macroamylase activity may be added the notion of in vitro variability for a sample conserved at -18 degrees C.

Alcoholism↗
PubMed1979

[Critical study of methods of estimation by an enzymatic method of serum triglycerides (author's transl)].

The authors describe a critical study of two entirely enzymatic methods of determination of serum triglycerides which differ mainly by the choice of hydrolytic agents: esterase and hydrolase by the Roche methods, lipase and esterase in the case of the Boehringer method. The estimation of the resulting free glycerol requires 3 sequential enzymatic reactions (glycerol kinase, pyruvate kinase, lactate dehydrogenase, ending by the measurement of the consumed reduced NAD. The study of the kinetics of the analysis in two stages is carried out using standard solutions of glycerol and with human sera of variable concentration; the optimal conditions of the reaction time and temperature are drawn up. The trials of repeatability and reproducibility from day to day were carried out together with evaluation of the precision. The method was compared with Beohringer's method (n = 50) using hydrolysis of alcoholic potash. The authors conclude on the use of the methods studied.

Esterases↗
PubMed1977

[Automated method for determining calcium in biological liquids].

A method of determination of calcium in biological fluids is proposed. It is a continuous flow technic without deproteinisation nor dialysis, using orthocresol phtaleine in alkaline medium. The interference due to magnesium is eliminated by the presence of hydroxy-8-quinoleine. The addition of dimethyl sulfoxide improves the solubility of the reagents and ensures better stability of the media. The correlation between the results obtained by this technic and by atomic absorption spectrophotometry was studied on 160 human sera and 40 urines. The influence of various parameters such as hemolysis, bilirubin, magnesium and phosphates is low or negligeable. The results concerning opalescent, cloudy or lactescent sera may be erroneous by excess. The physiological reference values for serum calcium are drawn up from a Paris student population of both sexes.

Autoanalysis↗