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M Masson

Publications and source records attributed to M Masson.

At least 55 records · Page 3Linked to original sources
PubMed1995

A new mutation in the HEXA gene associated with a spinal muscular atrophy phenotype.

We describe two adult siblings who had had mild GM2 gangliosidosis since childhood. They presented with spinal muscular atrophy and dysarthria, and one sibling also had mental disturbances. Laboratory studies established the diagnosis of the B1 variant of GM2 gangliosidosis, because the hexosaminidase (Hex) A deficiency was not present upon testing with the unsulfated synthetic substrate 4-methylumbelliferyl N-acetylglucosaminide. HEXA gene analysis proved that the patients are compound heterozygotes for the previously identified G533-->A mutation and for a new mutation, G1171-->A, at exon 11. This new mutation affects a conserved amino acid and results in a Val-->Met substitution at position 391 of the HEXA gene. Full sequence of the alpha-subunit cDNA of Hex A revealed no other mutation. Assays for Hex A activities in patients suspected of having GM2 gangliosidosis should be performed with the sulfated substrate 4-methylumbelliferyl N-acetylglucosamine 6-sulfate.

Adult↗
PubMed1995

Effect of folate supplementation on clinical chemistry and hematologic changes related to bidisomide administration in the rat.

In a chronic toxicity study in the rat, bidisomide administered as a dietary admixture produced a dose-related lowering of reticulocytes and leucocytes. Plasma alanine aminotransferase activity was increased at 300 mg/kg and decreased at 900 mg/kg. The potential mechanisms of these effects were investigated by comparing the responses in groups of male Sprague-Dawley rats receiving a control diet, or 300 or 1200 mg/kg/day bidisomide. Subsets of these groups were co-treated subcutaneously with folinic acid or with a vitamin B1, B6, B12 complex. Subsets of control and 300 mg/kg groups were maintained on a 20-25% feed restriction regimen for 3 months, to mimic the depression in body weight gain observed in animals receiving 1200 mg/kg. Body weight gains were significantly reduced at 1200 mg/kg and in all feed-restricted animals. Plasma and liver alanine aminotransferase (ALT) and plasma aspartate aminotransferase (AST) levels were also reduced at this dose level. At 300 mg/kg, plasma transaminases, glutamate dehydrogenase (GLDH) and sorbitol dehydrogenase (SDH) activities were increased. These changes were prevented in animals receiving folinic acid supplementation. Plasma glucose, triglycerides, and unsaturated and total iron binding capacities were decreased, while plasma iron levels tended to increase, mainly at the high dose. Vitamin supplementation prevented a decrease in reticulocyte counts at 300 mg/kg. Bidisomide increased urinary formimino-glutamic acid (FIGLU) excretion but did not affect methylmalonic acid (MMA) or taurine excretion. The effect on FIGLU at 1200 mg/kg was prevented by folinic acid co-treatment. Absolute liver weight was lowered at both dose levels and in feed-restricted animals. However, the relative liver weights were unaffected. Thymidine kinase and thymidylate synthase activity of the bone marrow cells were not altered by the bidisomide treatment. Except for the increase in plasma transaminase, GLDH and SDH levels at 300 mg/kg, changes in clinical chemistry parameters are considered to result mainly from nutritional restrictions. Changes in hematologic parameters appear to be related to the combination of decreased feed consumption (leukocytes) and decreased availability or utilization of folates (reticulocytes). This alteration, however, did not affect DNA synthesis in bone marrow. The prevention by folinic acid, but not by feed restriction, of the elevation of liver enzymes at 300 mg/kg is an intriguing, yet unexplained finding. There was no evidence that bidisomide affected B6 and B12 availability.

Alanine Transaminase↗
PubMed1995

[Liver mechanisms for the elimination of lipoproteins of intestinal origin].

This article critically examines the concept of the putative chylomicron remnant receptor (CMR). The molecular nature of this second lipoprotein receptor remains disputed. Indeed, two proteins, the low density lipoprotein receptor-related protein (LRP) and the lipolysis stimulated receptor (LSR) have been proposed as candidates for this function. The LRP bears significant structural homology with the LDL receptor and mediates the internalisation of beta-VLDL enriched with apo E. In addition, LRP binds several ligands not related to the lipoprotein system. Thus, LRP's contribution to the clearance of CMR has been questioned. The precise biochemical structure of LSR remains unclear. However, a series of observations support the hypothesis that LSR is the CMR receptor. LSR, which is activated by free fatty acis (FFA), the products of lipolysis, is present in primary cultures of rat hepatocytes. It displays the highest affinity for triglyceride-rich lipoproteins and is inhibited by lactoferrin. The existence of a strong inverse correlation in rats between the apparent number of hepatic LSR and the plasma triglyceride concentration measured in the post-prandial state, indicate that LSR represents a rate-limiting step for the removal of triglyceride-rich lipoproteins. Moreover, the ability of MAXEPA to enhance the expression of LSR in parallel with its well documented hypotriglyceridemic effect indicates that, contrary to popular belief, the putative CMR receptor represents a target for pharmacological management of hyperlipidemia.

Chylomicrons↗
PubMed1995

[Neurological applications of single photon emission tomoscintigraphy].

Brain single photon emission tomography is a functional imaging modality in constant evolution. Tracers belong to 4 categories; blood pool tracers, perfusion tracers, ligands of receptors, "metabolic" tracers. Examination conditions must be accurately described since they may cause specific cerebral activation. The interpretation must be done in comparison with a morphological examination (CT or NMR). Cerebrovascular diseases, temporal lobe epilepsy and dementia were the first domains of application. Now many studies concentrate on cerebral cognitive or pharmacological activation procedure before the tracer injection to capture an aspect of the brain functioning. It is mandatory to clearly state what is expected from the examination: an answer for a given patient and a specific question or a study of an homogeneous group of patients. In order to yield relevant results, such studies must rely on a rigorous methodology.

Cerebrovascular Disorders↗
PubMed1995

[Electrocardiographic anomalies in relation with infarction in the territory of the anterior choroid artery].

Electrocardiographic changes are seen in 5-17% of acute ischemic stroke, but there is scarpe clinical evidence to correlate stroke location with cardiac abnormalities. A 17-year old man had infarct in the territory of the anterior choroidal artery with major but reversible electrocardiographic changes. Infarction involved the substantia innominata containing the ventral amygdalofugal pathway. Electrocardiographic changes could result from a small hemispheric lesion of structures involved in autonomic control. Correlation studies of stroke location with electrophysiologic changes should help to determine patients at risk for cardiac arrhythmia and prevent sudden death.

Adolescent↗
PubMed1994

Structure and function of poly(ADP-ribose) polymerase.

Poly(ADP-ribose) polymerase (PARP) participates in the intricate network of systems developed by the eukaryotic cell to cope with the numerous environmental and endogenous genetoxic agents. Cloning of the PARP gene has allowed the development of genetic and molecular approaches to elucidate the structure and the function of this abundant and highly conserved enzyme. This article summarizes our present knowledge in this field.

Amino Acid Sequence↗
PubMed1994

Fasting for 24 h reveals liver microsteatosis after continuous i.v. infusion of milacemide in the rat.

Milacemide (2-n-pentylaminoacetamide) hydrochloride was administered by continuous i.v. infusion for up to 7 days, at 300 and 600 mg/kg per day to male Sprague-Dawley rats. This was intended to provide high and sustained exposure to evaluate the effect of a preterminal 24-h fast on liver lipid content. Liver lipid content, as assessed by triglyceride concentration and histopathology, was not different in saline controls or rats infused with up to 600 mg/kg per day for up to 7 days, when they had access to food up to sacrifice. When the rats were fasted for 24 h before sacrifice, milacemide produced microsteatosis in the periportal and midzonal areas. The effect was significant after 2 days of infusion at 600 mg/kg per day and increased in intensity with duration of administration. After 7 days of infusion, at 600 mg/kg per day, liver triglycerides increased by more than 4-fold in rats fasted for the last 24 h. No other differences from the controls were observed at light microscopy or in liver protein content and AST activity. Liver ALT activity was decreased by 28% and plasma ALT activity by 23%. Plasma triglyceride levels were lowered by milacemide, in both fasted and fed rats. This study demonstrates that fasting for 24 h triggers the development of liver microsteatosis in rats exposed to milacemide. Fasting has been previously described to increase liver microsteatosis after administration of sodium valproate, 4-en valproate and pentenoic acid in the rat. These findings might help to identify the mechanism of the hepatic effects of milacemide.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetamides↗
PubMed1994

[Apraxia and autotopoagnosia without aphasia or agraphia with compulsive language activity in right hemispheric lesion].

A 75 year-old woman was admitted with a left hemiplegia resulting from an infarct in the right middle artery's territory. Her manual preference was ambiguous from early childhood. She presented with severe bilateral apraxia, autotopoagnosia, finger agnosia, and left spatial neglect. There was, however, no aphasia nor agraphia. When the patient attempted to perform gestures on order, she compulsively produced oral or written language. In this very unusual case, dominance for gesture and dominance for language were strictly independent, each ensured by one hemisphere. The patient's performances in gestual activities, especially dissociation between automatic and voluntary movements, and compulsive linguistic productions, are discussed in relation to this functional lateralization. We suggest that the propositional nature of the responses required in test conditions could activate either voluntary language in the left cerebral hemisphere, or voluntary gestures in the right. A competition between the two hemispheres could explain the patient's linguistic apraxic or behavior in response to orders. Autotopoagnosia, an uncommon symptom, could interfere with apraxia, but is not directly responsible.

Aged↗
PubMed1994

[Hippocampothalamic infarction. A limited form of infarction in the posterior cerebral artery area].

Infarction of the hippocampus and the right ventroposterolateral thalamus was observed. Angiography revealed a posterior cerebral artery occluded near its origin, immediately upstream from the posterior communicating artery. The infarction was limited to the areas irrigated by the branches originating in the proximal part of the artery. More distal branches for the calcarine scissure and the temporooccipital gyruses were not involved.

Adult↗
PubMed1993

Cranial pachymeningitis of unknown origin: a study of seven cases.

We report seven patients with cranial pachymeningitis of unknown origin in whom the main clinical features were headaches, ataxia, and cranial nerve palsies. CSF showed inflammatory changes. CT and MRI showed thickening of the falx and of the tentorium. The clinical course was chronic. Four patients improved with prednisolone but became steroid-dependent: in two cases, radiotherapy had no lasting improvement and in one, azathioprine permitted a reduction of the corticosteroids. Five patients had biopsy of the tentorium cerebelli or of the temporal dura mater. In two cases, autopsy revealed extensive pachymeningitis without parenchymal changes. In all instances, microscopic examination of the dura mater showed a cellular infiltrate of polymorphic cells; there were no epithelioid granulomas. Review of the literature discloses seven similar cases. We discuss the relationship of these lesions with inflammatory meningeal masses, the focal pachymeningitis of the Tolosa-Hunt syndrome, and multifocal fibrosis.

Adult↗
PubMed1992

Calmodulin antagonists chlorpromazine and W-7 inhibit exogenous cholesterol esterification and sphingomyelinase activity in human skin fibroblast cultures. Similarities between drug-induced and Niemann-Pick type C lipidoses.

In this report we showed that calmodulin antagonists chlorpromazine (CPZ) and W-7 (N-[6-aminohexyl]-5-chloro-1-naphtalenesulfonamide), when added to fibroblast cell cultures, gave rise to a time- and dose-dependent decrease of sphingomyelinase activity. CPZ and W-7 also significantly inhibited LDL- and non-LDL-dependent cholesterol esterification. Addition of these drugs to cell culture medium mimicked what is observed in the genetic disease Niemann-Pick type C. H-7 (1-[5-isoquinonylsulfonyl]-2-methylpiperazine), an inhibitor of protein kinase C and cyclic nucleotide-dependent kinases, had no effect on sphingomyelinase and cholesterol ester formation. Thus the possibility of a modulation of cell sphingomyelin and cholesterol esters by a calmodulin-dependent second messenger system must be considered.

Calmodulin↗