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Biomedical subjects

P Levillain

Publications and source records attributed to P Levillain.

At least 73 records · Page 4Linked to original sources
PubMed1991

Improved fluorometric determination of malonaldehyde.

Lipoperoxidation is implicated in various pathological conditions. Malonaldehyde (MDA) is the most commonly used marker of this process. We propose simple modifications to Yagi's fluorometric assay for MDA determinations, to avoid long and tedious manipulations by eliminating the first precipitation and washing steps, analogous to HPLC methods, and to increase both the sensitivity and the specificity of the assay by measuring synchronous fluorescence. The proposed technique is easier, faster, and more sensitive than Yagi's method (Academic Press, 1982: Lipid peroxides in biology and medicine). The results obtained with the novel method correlate with those from the HPLC method described by Therasse and Lemonnier (J Chromatogr Biomed Appl 1987;413:237-41).

Chromatography, High Pressure Liquid↗
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

Simultaneous determination of hemoglobin and coproporphyrin by second derivative differential spectrophotometry: application to the diagnosis of meconium aspiration.

We describe a simple, fast method for simultaneous measurement of hemoglobin and coproporphyrin in urine and amniotic fluid, by second-derivative differential spectrophotometry. Both pigments were determined in biological samples without prior extraction. Despite the slightly overlapping spectra, the method permitted satisfactory resolution and avoided interspectral interference. Its sensitivity, sufficiently good, allowed to detect hemoglobin and coproporphyrin in slightly pathological urine and amniotic fluid as an aid to the diagnosis of meconium aspiration.

Amniotic Fluid↗
PubMed1989

[Prolonged hepatitis due to ajmaline--description of a case and review of the literature].

A 60 years old woman was admitted for jaundice and fever which appeared after a treatment with ajmaline-butabarbital for two-weeks. Abdominal ultrasound examination and endoscopic retrograde cholangiography were normal. Mitochondrial antibodies were absent. Jaundice persisted for three years, associated with diffuse cutaneous xanthomatosis. Five years later, alkaline phosphatases remained elevated. A liver biopsy showed vanishing interlobular bile ducts with centrolobular cholestasis and ductular proliferation. We suggest that ajmaline can induce long lasting cholestasis due to damage to the intrahepatic bile ducts. The responsibility of butabarbital and the relationship with primary biliary cirrhosis are discussed.

Ajmaline↗
PubMed1989

[Systemic mastocytosis disclosed by rupture of esophageal varices].

A 77-year-old woman had variceal bleeding related to systemic mastocytosis. Physical examination revealed minimal ascites and mild hepatomegaly noted 11 years before. Liver function tests were nearly normal. Because of early recurrent bleeding, a mesocaval shunt was performed. Wedged liver biopsy showed a moderate fibrosis of portal tracts and massive mast cell infiltration within portal tracts and sinusoids. Perisinusoidal collagen deposition was demonstrated ultrastructurally. We suggest that systemic mastocytosis be added to the list of diseases related portal hypertension with perisinusoidal fibrosis. As there is currently no specific treatment, a portocaval shunt should be discussed.

Aged↗
PubMed1989

[Hemangiopericytoma of the thyroid gland].

Hemangiopericytoma is an uncommon tumour of the thyroid gland. We report the fourth case of thyroid hemangiopericytoma in a 77 year-old woman who presented a goiter known for 23 years. The tumour, 11.5 X 7 X 7 cm in diameter, was located in the left lobe. Its histological features were those of a benign hemangiopericytoma as in two cases previously reported. Light microscopy discovered capillaries surrounded by sheets of plump cells and a reticulin network encircling each cell. A few tumour cells showed slight immunoreactivity with antibody against actin. There was no immunoreactivity with antibodies against desmin, vimentin and myosin intermediate filaments. Today, the electron microscopic analysis which revealed that tumour cells looked like pericytes, remains the best investigation for hemangiopericytoma diagnosis.

Aged↗
PubMed1989

[Direct spectrophotometric determination of urinary uroporphyrin and coproporphyrin using zerocrossing second derivative spectrophotometry].

The use of zero-crossing second-derivative spectrophotometry allows simultaneous determination of uroporphyrin and coproporphyrin directly in urines. Linearity and repeatability are excellent. Detection limit is about 8 nmol/l. Specificity is excellent too, except in unusual porphyrias where porphyrins with 5, 6 or 7 carboxylic groups are encountered. In such a case, this method allows the detection of increased porphyrins contents. The main advantage of this technique is its simplicity: it needs just to acidify urines and to plot a spectrum from 380 to 440 nm to determine the uroporphyrin and coproporphyrin concentrations. So it may be a very useful technic for clinical biochemistry laboratories in charge of monitoring patients suffering from porphyria.

Coproporphyrins↗
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↗
PubMed1987

[Glandulo-cystic polyps of the stomach. Apropos of 12 cases and review of the literature].

We report 12 cases of cystic glandular fundic polyps detected in 7 women and 5 men. As in the 238 similar previously reported cases these lesions were always located in the fundic gastric mucosae and did not involve the muscularis mucosae. They were discovered by endoscopy in patients with minor abdominal discomfort. They were less than 5 mm in diameter and were more often multiple and sessile; only a few of them were pedunculate. They consisted of mucosal cysts lined with cuboidal, parietal or chief cells and surrounded with a normal lamina propria. If in 213 cases, these polyps were not associated with polyposis coli in 37 cases they occurred with a Gardner's syndrome or a familial adenomatosis coli. These benign lesions are without malignant potential. Careful gastroscopic follow up with biopsy is recommended for all patients with multiple gastric polyps. The etio-pathogenesis of these polyps is still unknown. Their relationship to familial polyposis coli or to Gardner's syndrome is obscure.

Adenomatous Polyposis Coli↗
PubMed1987

Determining methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry.

We determined methemoglobin in blood by zero-crossing-point first-derivative spectrophotometry. After lysis of erythrocytes, hemoglobin was converted into oxyhemoglobin and the first derivative spectrum was recorded between 405 and 425 nm. At the exact point where the first-derivative spectrum of oxyhemoglobin was zero ("zero-crossing point"), the first-derivative value of oxyhemoglobin and methemoglobin mixture was proportional to the methemoglobin concentration. The standard curve was linear for all proportions of methemoglobin. Within-assay precision (CV) was 3.4% for a 20% methemoglobin content. Correlation with results by the Evelyn and Malloy method was very good for high proportions of methemoglobin (greater than 10%), but the proposed technique was far better for low methemoglobin percentages because of its linearity, its high sensitivity, and its low detection limit.

Humans↗
PubMed1986

[Lipids in the urine after extracorporeal shockwave lithotripsy].

Lipid corpuscles have been found in the urine in about 40 per cent of women (4/10) after extracorporeal shock wave lithotripsy, however this lipuria is very rare in men (1 or 2 per cent of cases) and less pronounced. During three days after treatment, this post-therapeutic lipuria was found to be independent of the age of patients, of the site of the calculi, of their chemical composition or of the number of shock waves administered. This lipuria probably results from the liquefaction of peri-pelvic fat tissue by exothermic reaction. These lipid corpuscles consist mostly of triglycerides and to a lesser extent phospholipids with a very small proportion of cholesterol and fatty acids.

Adult↗
PubMed1986

[Value of derivative spectrophotometry for the determination of plasma and urinary hemoglobin. Comparison with the method using Allen's correction].

We are proposing a technique enabling the dosage of hemoglobin in plasma or urine using spectrophotometry in derivative double dash. Around 420 nm hemoglobin has an elevated molecular extinction factor but the absorption of natural pigments creates a non-negligible interference in the classic spectrophotometric methods. On the contrary, the use of the derivative double dash enables to practically eliminate the background noise and to obtain a specific signal for hemoglobin while keeping an excellent sensitivity. In the plasma, where hemoglobin is entirely linked to haptoglobin, the dosage is done by direct reading (while in the urine the presence of several pigment forms requires the use of Drabkin's reagent. The method is simple, quick, precise and enables to titrate 1 mg.l (or 0.015 mumole.l-1) of hemoglobin. The influence of bilirubin is negligible. The comparison with a method using Allen's correction shows the superiority of the former as far as precision and accuracy are concerned, by avoiding the danger of a non-negligible systematic error.

Hemoglobins↗