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C Desnuelle

Publications and source records attributed to C Desnuelle.

At least 37 records · Page 2Linked to original sources
PubMed1997

Cloning and expression analysis of a meiosis-specific MutS homolog: the human MSH4 gene.

The Escherichia coli MutHLS system has been highly conserved throughout evolution. The eukaryotic pathway results in a specialization of MutS homologs that have evolved to play crucial roles in both DNA mismatch repair and meiotic recombination. So far, meiosis-specific genes belonging to this family have only been identified in yeast. In Saccharomyces cerevisiae, MSH4 (MutS homolog 4) is a meiosis-specific protein that is not involved in mismatch correction. This protein is required for reciprocal recombination and proper segregation of homologous chromosomes at meiosis I. We have identified the human MSH4 homolog gene. The predicted amino acid sequence shows 28.7% identity with the S. cerevisiae MSH4 protein. By Northern blot analysis, human MSH4 transcripts are only detectable in testis and in ovary with a lower level of expression. We have mapped MSH4 to human chromosome 1 at band p31 by fluorescence in situ hybridization. The identification of such a gene provides a powerful tool for clarifying the respective roles of MSH and MLH genes in mammalian meiosis.

Adenosine Triphosphatases↗
PubMed1997

Phenotypic expression of diabetes secondary to a T14709C mutation of mitochondrial DNA. Comparison with MIDD syndrome (A3243G mutation): a case report.

OBJECTIVE: To analyze the clinical and biochemical features of a recently described point mutation of mitochondrial DNA associated with diabetes. This mutation, characterized by a T14709C transition of a highly conserved nucleotide in the region coding for the glutamic acid tRNA, is heteroplasmic. RESEARCH DESIGN AND METHODS: The phenotypic expression in the insulin-requiring diabetic proband from the pedigree was compared to that of diabetic probands from three families with the classic A3243G mtDNA mutation (maternally inherited diabetes and deafness [MIDD] syndrome). The same investigations to evaluate pancreatic neurosensorial and muscle involvement were performed in all four patients. RESULTS: The natural courses of the diabetes and the hearing defects were not different between the two mutations. The patient with the 14,709 mutation, however, exhibited a milder alteration of pigmentary epithelium of retina and a much more severe muscle involvement, as attested by the clinical expression and the concurrent anomalies of muscle energy production evidenced by 31P magnetic resonance spectroscopy, confirming the profound impairment of oxidative processes. CONCLUSIONS: This novel mutation has to be added to the other known mtDNA anomalies in order to ascribe some diabetes suspected to arise from mitochondrial defects to this nosological framework.

Adult↗
PubMed1996

Plasma concentrations and pharmacokinetics of idebenone and its metabolites following single and repeated doses in young patients with mitochondrial encephalomyopathy.

OBJECTIVE: The pharmacokinetics and tolerance of idebenone after single or repeated doses have been studied in young patients with mitochondrial encephalomyopathy. RESULTS: No significant adverse effects were noted. In 3 out of 7 patients idebenone induced overall stimulation and improvement in arousal. Plasma concentrations of idebenone and its main metabolites were determined and the pharmacokinetic parameters of idebenone after single and repeated doses were estimated. During the single dose study, the mean plasma concentrations of idebenone and its main metabolites and mean pharmacokinetic parameters were comparable to published results (Cmax = 452.2 ng.ml-1, tmax = 2.3 h, AUC = 26 micrograms. ml-1.h, t1/2 beta = 16.5 h). During the repeated doses study, no significant difference was found between mean residual plasma concentrations of idebenone on Day 2 (47 ng.ml-1) and Day 5 (70.6 ng.ml-1), and mean t1/2 beta of idebenone after the single and after repeated dose studies, i.e., there was no evidence of accumulation. Although idebenone did not appear to accumulate during this study, the coadministration of anticonvulsants, often prescribed during mitochondrial encephalomyopathy, can affect its pharmacokinetics.

Adolescent↗
PubMed1996

A controlled one-year trial of dextromethorphan in amyotrophic lateral sclerosis.

In a one-year parallel group double-blind placebo-controlled study of dextromethorphan (1.5 mg/kg) in amyotrophic lateral sclerosis, no significant differences were observed in the rate of progression (Norris scale) in comparing 24 patients randomly assigned to the dextromethorphan group and 25 patients randomly assigned to the placebo group. Of the 24 patients in the dextromethorphan group, 17 had limb onset and 7 had bulbar onset disease; average duration of disease was 12.5 +/- 6 months and sex ratio (M:F) was 1.4:1. Of the 25 patients in the placebo group, 18 had limb onset and 7 had bulbar onset disease; average duration of disease was 9.9 +/- 6 months and sex ratio (M:F) was 1.55:1. Dextromethorphan is a weak noncompetitive N-methyl-D-aspartate (NMDA) antagonist and higher doses or other potent NMDA receptor antagonists should be tested.

Adult↗
PubMed1996

[Migraine and mitochondrial dysfunction].

Like many others neurological diseases, mitochondrial involvement, by means of abnormalities in cerebral oxidative metabolism, may play a role in migraine. This review summarizes clinical data, in vivo magnetic resonance spectroscopy studies, biochemical assays and therapeutic results that support the "mitochondrial hypothesis of migraine".

Brain↗
PubMed1995

Levorotatory form of 5-hydroxytryptophan in Friedreich's ataxia. Results of a double-blind drug-placebo cooperative study.

OBJECTIVE: To study the effect of the levorotatory form of 5-hydroxytryptophan on the cerebellar symptoms of Friedreich's ataxia. DESIGN: Cooperative double-blind study of the levorotatory form of 5-hydroxytryptophan vs placebo. SETTING: Twelve centers in research hospitals. PATIENTS: Twenty-six patients were included; 19 completed the study (mean +/- SD age of patients, 25.9 +/- 8.1 years). Of these 19 patients, eight were treated with placebo and 11 were treated with the drug. MAIN OUTCOME MEASURES: A semiquantitative scale for kinetic and static ("postural") cerebellar functions and quantitative measurements of time in standard tests that evaluated stance, speech, writing, and drawing. RESULTS: In the active treatment group, a significant decrease of the kinetic score was observed (P = .03), indicating an improvement in coordination. CONCLUSIONS: These results demonstrated that the levorotatory form of 5-hydroxytryptophan is able to modify significantly the cerebellar symptoms in patients with Friedreich's ataxia. However, the effect is only partial and not clinically major.

5-Hydroxytryptophan↗
PubMed1995

Early-onset fatal encephalomyopathy associated with severe mtDNA depletion.

UNLABELLED: We studied a 3-month-old girl who was admitted to hospital because of respiratory distress. The clinical course was characterized by a rapidly progressive generalized hypotonia with lactic acidosis and she died at 4 months of age. A muscle biopsy showed few ragged-red fibres and lack of histochemical cytochrome c oxidase reaction in all fibres. Enzyme activities of the respiratory chain complexes containing subunits encoded by the mitochondrial DNA (mtDNA) were markedly decreased. A quantitative Southern blot analysis revealed 99% depletion of mtDNA in muscle and normal amounts in blood. There was no family history and the dizygotic twin sister of the patient was no symptomatic. CONCLUSION: This new case confirms the rapidly fatal evolution associated with severe depletion of muscle mtDNA.

Acidosis, Lactic↗
PubMed1995

[Muscular involvement in the course of AIDS. Anatomo-clinical study of 17 cases].

We report 17 patients seropositive for the human immunodeficiency virus, with muscle tissue involvement in different stages of the disease. Some patients are treated with azidothymidine (AZT). Others have no opportunistic infections. In all cases, there are some muscular symptoms such as progressive symetric and proximal muscular weakness with myalgias, elevated serum muscle enzymes, abnormal electromyogramma and very often a peripheral neuropathy. The muscle biopsy reveals the following features: rarely a focal muscular opportunistic infection in advanced stage of the disease is observed; a polymyositis is quite often the first clinical manifestation of the disease; a myopathy with mitochondrial involvement is observed in some of the AZT treated patients; some cachectic, under nourrished, bedridden patients present a type II muscle fiber atrophy. We conclude that a muscle biopsy could help us in our therapeutic planning directing us to a corticotherapy in the polymyositis, mitochondriopathies and wasting syndrome. Interruption alone of AZT or associated with a treatment by carnitine could allow remission of the muscular pathology.

Acquired Immunodeficiency Syndrome↗
PubMed1994

[Lessons of dystrophin].

The fantastic advances in fundamental research into muscular dystrophy over the past few years have led to the discovery of a cytoskeleton protein called dystrophin and a group of associated and analogous molecules. The understanding of their molecular structure and the modes of genetic and functional regulation have forced us to take a new look at our concept of the pathogenesis of muscular dystrophy. Today, the group of diseases called X-linked hereditary muscular dystrophies must now be conceived in light of a deficiency in dystrophin. The exact physiopathology of the process involved is not yet fully understood but most undoubtedly, although the lack of dystrophin can trigger the disease, the deficiency cannot in itself impede muscle contraction. As a result of these discoveries, diagnostic methods have changed drastically, genetic counselling has become more precise, and most importantly, new treatment rationales can call upon pharmacological processes capable of stopping disease progression. Genetic therapy is another approach. The aim is to provide the deficient cells with the capacity of synthesizing normal dystrophin or an analogous molecule, thus halting the cascade of events leading to necrosis. The transfer of the technical means which have made these fundamental advances in basic research possible to successful clinical applications in the treatment of muscular dystrophy will be another of the lessons to be learned from dystrophin.

Dystrophin↗
PubMed1994

Mitochondrial respiratory failure in skeletal muscle from patients with Parkinson's disease and multiple system atrophy.

We studied mitochondrial respiratory chain function in skeletal muscle taken from 27 patients with idiopathic Parkinson's disease (PD; 21 Dopa-treated PD patients and 6 de novo patients), 5 patients with multiple system atrophy (MSA) and from 43 age-matched controls in order to determine the occurrence of mitochondrial respiratory chain abnormalities in parkinsonian syndromes. In our control subjects, we found a significant age-related decrease in the activity of respiratory chain complex I. As compared to carefully age-matched control subjects, activity of complex (NADH:ubiquinone reductase) was significantly lower in muscle mitochondria from patients with PD and MSA and a mean remaining activity < 30% of controls was observed. Mean activities of complexes III (ubiquinol:cytochrome c reductase) and IV (cytochrome c oxidase) were also lower in PD patients than controls, but a low activity (remaining activity < 30% of controls) was observed in only 5 PD patients for complex I and III or I and IV. No deficit in complex II activity (succinate:ubiquinone reductase) was observed. Our results support the hypothesis of a wide-spread mitochondrial complex I deficiency in PD and MSA as compared to age-matched controls, who showed age-related deficiency. This deficit can be found in de novo PD patients as well as in treated patients. The observed respiratory enzyme chain deficiency could not be explained by the dose and duration of L-Dopa or dopaminergic agonist treatment, the severity of the disease, anxiety or depression since no significant correlation was found between these parameters and enzyme complexes activities.

Adult↗
PubMed1994

Mutations in the muscle sodium channel gene (SCN4A) in 13 French families with hyperkalemic periodic paralysis and paramyotonia congenita: phenotype to genotype correlations and demonstration of the predominance of two mutations.

Hyperkalemic periodic paralysis (hyperPP), paramyotonia congenita (PC) and PC with myotonia permanens are closely related muscle disorders of genetic origin due to allelic mutations in the muscle sodium channel gene, SCN4A. Seven families of French origin with hyperPP were studied. Five of these had the Thr704Met mutation, but 2 families, genetically linked to SCN4A, failed to show any of the known mutations of SCN4A. Correlations between the phenotype and the genotype were made for patients with the Thr704Met mutation. All 12 patients over 30 years old with the Thr704Met mutation presented muscle weakness due to degeneration of muscle fibers in addition to periodic paralysis. Only approximately 12.5% of patients with the Thr704Met mutation presented with clinical myotonia and about 50% with hyperkalemia. One family with PC displayed the Gly1306Val mutation with a phenotype similar to the one already reported for this mutation. Five families with either PC or PC with myotonia permanens had the Thr1313Met mutation indicating that the severity of myotonia and its permanence were variable. Two mutations of SCN4A were found to be predominant in these 13 families: the Thr704Met and the Thr1313Met mutations. Only 2 families with the Thr704Met mutation and 3 families with the Thr1313Met shared the same SCN4A haplotype determined with intragenic dinucleotide repeats. Recurrent mutations of SCN4A may contribute to the predominance of these two mutations in the French population.

Adolescent↗
PubMed1994

[Mitochondrial encephalopathies with late disclosure and predominant involvement of central nervous system].

We report three cases of mitochondrial encephalomyopathy affecting predominantly the central nervous system; two patients had the MELAS syndrome and one had "ophthalmoplegia plus". Histoenzymatic analysis of muscle biopsy and biochemical studies of muscle mitochondria demonstrated myopathy associated with partial deficiency of complex I of the electron transfer chain in three cases, complex IV in two cases and complex III in one case. Molecular analysis of mtDNA in the first case did not revealed any abnormality. Coenzyme Q10 therapy improved exercise tolerance but not the central nervous signs.

Adult↗
PubMed1994

[Lambert-Eaton syndrome without calcium channel autoantibodies].

Two cases of Lambert-Eaton syndrome are reported, one associated with a small cell lung carcinoma, the other without any etiology at the time of the study. None of these cases showed significant titers of calcium channel autoantibodies. The heterogeneity of the Lambert-Eaton syndrome and the responsibility of the autoantibodies detected by immunoprecipitation of the voltage-gated calcium channel in the occurrence of the neuromuscular block are discussed.

Adult↗