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Biomedical subjects

B Mousson

Publications and source records attributed to B Mousson.

At least 37 records · Page 2Linked to original sources
PubMed1995

An abnormal exercise test response revealing a respiratory chain complex III deficiency.

A 29-year-old man with a progressive exertional muscle intolerance since childhood was referred for incremental exercise test on a bicycle ergometer. The response pattern suggested a mitochondrial myopathy: that is, a greatly reduced maximum oxygen consumption with appropriate heart rate increase and an anaerobic threshold point reached early. The metabolic investigation in plasma revealed an abnormal oxidoreduction status (hyperlactataemia and high lactate/pyruvate ratio) at rest and after a carbohydrate rich meal. The histochemical examination of a muscle biopsy revealed red granular deposits under the sarcolemma for all type 1 fibers. Oxypolarographic and enzymological studies of the mitochondrial respiratory chain in both isolated mitochondria and muscle homogenate demonstrated a marked deficiency of ubiquinol cytochrome c reductase (complex III) activity.

Adult↗
PubMed1995

Serum 5'-nucleotidase and alkaline phosphatase activities after high dose chemotherapy and bone marrow transplantation in cases of malignancy in children.

After bone marrow transplantation in children, it is essential to detect secondary liver diseases and hepatotoxic effects of immunosuppressive therapy. These can be revealed by cytolytic syndromes sometimes associated with cholestasis. It is therefore important to find an early and specific cholestasis enzymatic marker. A retrospective study of the changes in levels of biological parameters has been carried out in 13 children who underwent one or more bone marrow transplantations. During the 3 months following bone marrow transplantation, all patients developed liver injury characterized by an early and very elevated 5'-nucleotidase activity (sometimes more than 40 times the upper reference limit), a moderate increase in alkaline phosphatase activity, a variable increase in alanine aminotransferase activity and inconstant changes in total bilirubin levels. These results show that cytolytic syndrome and cholestasis are often associated with increases in 5'-nucleotidase and alkaline phosphatase activities. These increases are not correlated, probably due to the influence of therapy on the synthesis and release of both enzymes in the liver. 5'-nucleotidase seems to be the best marker for the detection and follow-up of liver disease in this patient group.

5'-Nucleotidase↗
PubMed1994

Rate-dependent distal renal tubular acidosis and carnitine palmitoyltransferase I deficiency.

An infant girl presented with recurrent episodes of Reye-like syndrome associated with hypoketosis and plasma carnitine levels in the high-normal range. A liver biopsy revealed massive macrovesicular steatosis. Ketogenesis was absent after a long-chain triglyceride loading test; in contrast, the medium-chain triglyceride loading test resulted in a brisk rise in plasma ketone concentration. Carnitine palmitoyltransferase I deficiency was demonstrated in cultured skin fibroblasts. Hypoglycemia was only found once in the neonatal period. Renal carnitine handling was normal except for a higher renal threshold for free carnitine. Mild, persistent metabolic acidosis was a constant feature, even during periods between metabolic decompensation. Evaluation of the renal acidification capacity showed a failure to acidify the urine during spontaneous acidosis but increased acid excretion and a normal decrease of urinary pH after acid loading. Also, a small difference between urine and blood PCO2 was found after bicarbonate administration. This acidification defect can best be explained as an abnormality in distal tubular H+ secretion: a rate-dependent distal tubular acidosis.off is speculated that long-chain acylcarnitines, substances that cannot be formed by carnitine palmitoyltransferase I-deficient patients, play an essential role in renal acid-base homeostasis.

Acidosis, Renal Tubular↗
PubMed1993

2-Ketoglutarate dehydrogenase deficiency, a rare cause of primary hyperlactataemia: report of a new case.

Two new familial cases of 2-ketoglutarate dehydrogenase (2-KGD) deficiency are reported: a girl who died at 10 years and a boy, still alive at 4 years, born to consanguineous parents. The cases developed progressively severe encephalopathy with axial hypotonia, psychotic behaviour, pyramidal symptoms and failure to thrive. Both children exhibited permanent lactic acidosis with acute episodes during emotional stress and various infections, associated with elevated lactate/pyruvate (L/P) ratio and slightly decreased ketone body ratio in plasma. In fibroblasts, the L/P ratio was greatly increased in the boy. No respiratory chain complex deficiency could be demonstrated in cultured fibroblasts or in mitochondria isolated from a muscle biopsy performed on the boy. In muscle isolated mitochondria, a progressive decrease of the rate of glutamate oxidation was observed after ADP addition; the rate of 2-ketoglutarate oxidation was low in the absence of ADP and did not increase after ADP addition. 2-KGD deficiency was demonstrated in fibroblasts from both children and in the boy's muscle and myoblasts. The 2-KGD complex is composed of three separate enzymes: E1, E2 and E3. We could demonstrate in our patient that the E1 and E3 subunits were normal, suggesting that the E2 component could be responsible for the defect.

Acidosis, Lactic↗
PubMed1993

Carnitine palmitoyl transferase I deficiency presenting as a Reye-like syndrome without hypoglycaemia.

An apparently healthy girl aged 2 years 9 months developed a coma with hepatomegaly within 24 h after an influenza-like infection. Plasma glucose and urinary organic acid profile were normal but plasma and urinary carnitine concentrations were increased. Despite symptomatic therapy, she died 11 days later. Oxidation of [1-14C] palmitic acid in the patient's fibroblasts was severely decreased (13% of controls). Further investigations revealed a deficiency of carnitine palmitoyl transferase I (CPT I) in the patient's fibroblasts (15% of controls) whereas CPT II activity was normal. Only four patients with CPT I deficiency have been reported so far. The subtle clinical and biochemical presentation of this disorder, which may account for the small number of cases diagnosed, is discussed.

Carnitine↗
PubMed1993

Failure to obtain hybridomas between human macrophages and human tumoral U-937 cells is probably due to parental macrophages.

Despite more than 50 attempts and the use of various methods, it has been impossible to establish homologous hybridomas between human mature macrophages and 8-azaguanine-resistant U-937 clones prepared in the laboratory. To rule out the possibility that these clones were unsuitable for the selection of hybrids, a study of their properties was done. It was shown that U-937 wild type cells were able to produce HPRT, whereas 8-azaguanine (8-aza)-resistant clones did not. Curiously, exonic and intronic HPRT sequences were undetectable both in wild type and in 8-aza-resistant cell genomes, under conditions where they were detected in control cells. Chromosome analysis of the clone UM9, one of the most frequently used in fusion experiments, revealed many qualitative and quantitative differences with the U-937 wild type cells. 8-aza-resistant U-937 cells were capable of fusion with human macrophages and gave rise to heterokaryons and probably to synkaryons, which survived for weeks without dividing in hypoxanthine-aminopterin-thymidine medium. The results could be interpreted in terms of the existence of a transacting negative regulatory mechanism of the macrophage genome on the proliferative capacity of homospecific hybridomas.

Animals↗
PubMed1993

[Value of skin fibroblasts in culture for the diagnosis of mitochondrial cell dysfunction. Apropos of 5 cases with cytochrome c oxidase deficiency].

Mitochondrial respiratory chain dysfunction has been studied by two complementary methods using cultured skin fibroblasts from five patients with muscular cytochrome c oxidase (complex IV) deficiency: first, a screening test measuring lactate to pyruvate ratio (L/P) after supplementation of cultured cells; secondly, measurement of complex IV activity in whole cells. Respiratory chain defect (increased L/P ratio with decreased complex IV activity) was expressed in fibroblasts of four of the five patients. Our results show that skin fibroblasts can be helpful for biochemical diagnosis of mitochondrial respiratory chain defects.

Cells, Cultured↗
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↗
PubMed1990

[Evaluation of a technique for determining blood ethanol levels by gas chromatography. Committee for "determination of blood ethanol levels"].

Art. R.24-1 of the Code governing distribution of beverages and preventive measures against alcoholism: "If the verifications are performed following a traffic accident having occurred under the conditions provided at article L.88 of the present code or in application of articles L.1 and L.3 of the traffic code, the requesting authority keeps a copy of form A and sends: 1. The first blood specimen samples, along with four copies of forms A, B and C, to a laboratory of an establishment part of the public hospital system as defined at article 3 of law n. 70-1318 of December 31 1970 or to an expert biologist registered on the list held by the court of appeals as provided by article R.32 of the code governing distribution of beverages and preventive measures against alcoholism; 2. The second sample, along with one copy of forms A, B and C, to another expert biologist registered on the same list and in charge of eventually performing a control analysis. The laboratory or the expert biologist having performed the analysis reports the results on forms C and forwards one copy of forms A, B and C directly, under separate cover and stamped confidential to the competent Procureur de la Republique, to the region in which the misdemeanor or the accident occurred. The results reported on the form are immediately transmitted to the requesting authority.

Chromatography, Gas↗
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↗
PubMed1988

[Recurrent rhabdomyolysis and deficiency of carnitine palmityl transferase. Evidence of the responsibility of a mutant in 2 brothers].

In two brothers who had been presenting since childhood with intermittent muscular attacks and myoglobinuria after sustained efforts, muscle carnitine palmityl transferase (CPT) activity was undetectable by the backward hydroxamate colorimetric method. Such a total deficiency could not easily fit in with the clinical features (normal muscular activity outside sustained efforts), with the normal results obtained at electromyography and with the moderate fatty overload detected at muscle biopsy. In order to elucidate these apparently discordant findings, another CPT measurement method, the forward optimized isotopic technique, was used. With this method, the catalytic activity of CPT can be measured, and enzyme inhibition by its substrate and the product of the reaction (palmityl CoA and palmitylcarnitine respectively) can be studied. The results showed that the catalytic activity of CPT was preserved in both patients, but the enzyme was abnormally sensitive to inhibitors. These 2 cases tend to demonstrate the existence of a mutant carnitine palmityl transferase.

Acyltransferases↗
PubMed1988

Prevention of neonatal hypoglycaemia by oral lipid supplementation in low birth weight infants.

The effect of oral lipid supplementation (2.9 g/day containing 67% medium chain triglycerides) on the prevention of neonatal hypoglycaemia was evaluated in 28 low birth weight infants (mean +/- 1 SD for gestational age: 36 +/- 1.2 weeks and birth weight: 1778 +/- 230 g) and compared to a control group of 23 infants with similar gestational age, birth weight and sex. The incidence of hypoglycaemic patients with plasma glucose less than 1.72 mmol/l was 8/23 (35%) in the control group versus 2/28 (7%) in the supplemented group: chi 2 = 6.72; P less than 0.01. Determinations of plasma beta-hydroxybutyrate concentrations in 11 infants of the supplemented group did not show values higher than 1.2 mmol/l. This prospective study shows that supplementation with lipids can prevent the occurrence of hypoglycaemia in low birth weight infants.

Female↗
PubMed1983

Measurement of xanthine oxidase activity in some human tissues. An optimized method.

Xanthine oxidase activity in human liver or jejunum homogenates was measured by using 8-14C-hypoxanthine (HX) as a substrate. Products of oxidation were separated by thin-layer chromatography on MN Polygram cellulose and located by autoradiography. The percentage of oxidation was measured by liquid scintillation. Main parameters of the enzyme reaction have been optimized. Repeatability and reproducibility of the overall procedure give a variation coefficient of 6.3 and 7.7%, respectively. Minimal detectable enzymatic activity corresponds to an oxidation percentage of 1% (HX) for liver and jejunum. The reliability and practicability of this method allow a rapid diagnosis of xanthine oxidase deficiency. Normal values obtained by this optimized method range between 25 and 42 mukat . kg-1 protein for liver and 18 and 40 mukat . kg-1 protein for jejunum.

Carbon Radioisotopes↗
PubMed1983

Continuous assay of serum 5-nucleotidase activity with inosine 5'-monophosphate as substrate and total automation using a transfer-analyzer (Kem-O-Mat).

The continuous spectrophotometric assay of 5'-nucleotidase originally described by Heinz et al. ((1980) J. Clin. Chem. Clin. Biochem. 18, 781-788) was modified and fully automated on a Kem-O-Mat transfer analyzer, using inosine 5'-monophosphate as substrate. The reaction product was hydrogen peroxide and the reduction of NADP was observed for 10 minutes at 340 nm and at a reaction temperature of 30 degrees C. The different factors involved in the enzyme reaction were checked, including the substrate concentration, reaction rate, linearity and substrate preservation. Normal values ranged from 1 to 13 U/l. Between-day reproducibility was estimated with two different commercial control sera, and the coefficient of variation was 5% for the upper limit of normal activity (23 U/l). There was good agreement between the present method and a semi-automatic colorimetric technique (for 100 sera tested by both methods, the correlation coefficient was 0.974 and the regression line equation, y = 0.85 x- 1.5). Despite the lengthy reagent mixture preparation procedure, the method permitted assay of 50 samples per hour. The occurrence of high serum blanks in certain pathological states is discussed.

5'-Nucleotidase↗