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Biomedical subjects

G Jasmin

Publications and source records attributed to G Jasmin.

At least 55 records · Page 3Linked to original sources
PubMed1986

Evaluation of the hereditary Syrian hamster cardiomyopathy by 31P nuclear magnetic resonance spectroscopy: improvement after acute verapamil therapy.

The relation between metabolic and functional derangement in various cardiomyopathies has not been well characterized. This information was specifically sought in a spontaneous cardiomyopathic model. Metabolic and hemodynamic parameters were obtained in glucose-perfused beating hearts of 180-200-day-old cardiomyopathic Syrian hamsters and age-matched healthy animals. This period in the cardiomyopathic hamster lifetime is intermediary between the necrotic phase and the appearance of heart failure. We used 31P nuclear magnetic resonance spectroscopy to analyze energy metabolites and intracellular pH. Cardiomyopathic hamsters had significantly higher mole fraction values for inorganic phosphate, lower phosphocreatine mole fraction as well as lower phosphocreatine/inorganic phosphate and adenosine triphosphate/inorganic phosphate ratios. Analysis of pH indicated the presence of regions of increased acidity within the heart of myopathic hamsters. Cardiomyopathic hamsters also had significantly lower left ventricular pressure, coronary flow, and myocardial oxygen consumption. Separate groups of normal and myopathic hamsters were given verapamil for 24 hours (one injection of 4 mg/kg s.c. followed by 1.2 g/l in drinking water). Verapamil-treated myopathic hamsters had evidence of markedly improved mitochondrial function when compared with untreated animals. Left ventricular pressure and coronary flow rose to normal levels. Replacing glucose by pyruvate in the perfusate of myopathic hamsters results in a marked increase in left ventricular pressure, coronary flow, and oxygen consumption with a moderate rise in phosphocreatine. Thus, 180-200-day-old cardiomyopathic hamster heart is characterized by evidence of decreased mitochondrial function, by areas of increased acidity within the heart, and by reduced left ventricular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1985

Sarcolemmal Na+-Ca2+ exchange during the development of genetically determined cardiomyopathy.

The UM-X7.1 myopathic and control hamsters at 40, 120 and 280 days of age were employed for the examination of heart sarcolemmal Ca2+-transport activities. Na+-dependent Ca2+ uptake activities were significantly depressed in myopathic animals at 120 and 280 days of age in comparison to the control values. No difference in Na+-induced Ca2+ release activities was found between control and experimental sarcolemmal vesicles. ATP-dependent Ca2+ binding and Ca2+-stimulated, Mg2+ ATPase activities were depressed in the experimental animals at 120 and 280 days of age. Similar alterations in the sarcolemmal Na+-dependent Ca2+ exchange and Ca2+-pump activities were seen upon treating the control hamsters with 40 mg/kg isoproterenol for 24 hr. It is suggested that a depression in the sarcolemmal Ca2+ transport activities may contribute to the development of intracellular Ca2+ overload in the genetically determined cardiomyopathy in hamsters and such a defect may be due to excessive amount circulating catecholamines in these animals.

Aging↗
PubMed1984

The Andermann syndrome: agenesis of the corpus callosum associated with mental retardation and progressive sensorimotor neuronopathy.

Andermann et al. described in 1972 an autosomal recessive inherited syndrome which associates agenesis of the corpus callosum, mental deficiency, and a peripheral motor deficit. We had the opportunity to study in detail 15 patients affected by this syndrome. As in the cases previously reported, the families of these children all originated from Charlevoix County and the Saguenay-Lac St-Jean area in the Province of Quebec. Clinically, these patients have a characteristic facies and moderate mental retardation associated with a progressive motor neuropathy leading to loss of ambulation by adolescence and progressive scoliosis. In 13 of these 15 patients, neuroradiological investigation has shown either total or partial agenesis of the corpus callosum. In every patient in whom these tests were done, sensory nerve action potentials were absent and motor nerve conduction velocities reduced. We also found neurogenic abnormalities both on EMG and neuromuscular biopsies. These abnormalities are similar to those described in Friedreich's ataxia and in hereditary motor and sensory neuropathy type II, although in our patients the motor deficit is much more severe than in these diseases. The pathogenesis of the peripheral nervous system involvement is still unknown since there have so far been no autopsy studies of this syndrome.

Adolescent↗
PubMed1984

Sarcolemmal alterations during the development of genetically determined cardiomyopathy.

The purpose of this study was to identify alterations in specific enzyme and Ca2+ binding activities in cardiac sarcolemmal fractions from UM-X7.1 myopathic Syrian hamsters during the development of cardiomyopathy. Experimental and healthy control animals were examined from 25 to 200 days of age. Sarcolemmal Na+, K+-ATPase activity was depressed in the myopathic hamsters throughout the time course of this study. Sarcolemmal ATP-independent Ca2+ binding was found to be depressed in experimental animals as early as 55 days of age. Ca2+ -stimulated, Mg2+ -dependent ATPase activity was depressed in the experimental animals by 90 days of age and this decrease in enzyme activity was accompanied by a decrease in ATP-dependent Ca2+ binding capacity of the sarcolemmal membranes. Mg2+ -ATPase and Ca2+ -ATPase activities were only affected in the latter stages of the disease (155 to 200 days old). NaF, epinephrine and Gpp(NH)p stimulation of the sarcolemmal adenylate cyclase activity was also observed to be attenuated during the latter stages of the disease. These defects in adenylate cyclase system of the sarcolemmal fraction appeared specific since basal adenylate cyclase activity was not altered at any age studied. The results demonstrate that the earliest lesions in sarcolemmal activity in myopathic hamster heart occur in Na+, K+-ATPase and ATP-independent Ca2+ binding capacity. These defects correspond temporally to the initial stages of cardiac necrotic development in this strain of myopathic hamster.

Adenosine Triphosphatases↗
PubMed1984

Calcium and myocardial cell injury. An appraisal in the cardiomyopathic hamster.

The heart muscle is very compliant within a wide range of physiologic impulses. The adaptive energy of the myocardium depends, however, upon adequate oxygen supply and the functional state of the plasmalemma. These limitations have been well demonstrated in a number of experimental models with emphasis on the essential role of Ca2+ transmembrane movements for maintenance of heart functions and its viability. This postulate appeared quite important when we found that Ca2+ slow channel blockers could prevent necrotic changes in hamster hereditary cardiomyopathy. However, the effectiveness of beta-adrenoagonists when given in low doses seems more difficult to interpret since these agonists can only promote Ca2+ transmembrane movements. We can only surmise that Ca2+ accumulation in cardiomyopathic hearts does not derive from a primary defect of the plasmalemma but rather from an exhausted hypokinetic state that favours Ca2+ accumulation with progressive deterioration of the structural proteins. It is thus inferred that Ca2+ mediates rather than initiates the degradation process which characterizes this inherited cardiomyopathy.

Animals↗
PubMed1984

Giant cell pneumonia due to respiratory syncytial virus. Occurrence in severe combined immunodeficiency syndrome.

A 6-month-old male infant with a severe combined immunodeficiency syndrome was hospitalized for progressive respiratory distress. Examination during hospitalization disclosed widespread pulmonary infiltrates that did not respond to intensive therapy. The patient died eight days after admission. Autopsy disclosed Pneumocystis carinii pneumonia and widespread giant cell pneumonia. Respiratory syncytial virus (RSV) was grown from a lung specimen obtained at autopsy. Specific immunofluorescent staining of the cytoplasm of alveolar lining cells with RSV antiserum was demonstrated. The electron microscopic appearance of giant cells was compatible with RSV infection. The RSV should be added to the list of viruses causing giant cell pneumonia.

Humans↗
PubMed1984

Impaired muscle differentiation in explant cultures of Duchenne muscular dystrophy.

Muscle cultures were established from 11 normal controls and 13 Duchenne muscular dystrophy biopsies by an explant technique. Under light microscopy the most distinctive features of Duchenne muscular dystrophy cultures were an earlier migration and a delay or even an absence of fusion of mononucleated cells in comparison with the controls. Furthermore, most fusing dystrophic cells were morphologically different from conventional myoblasts, and, at a later stage, myotube formation was significantly reduced. In contrast to controls, dystrophic cultures displayed a total absence of spontaneous contractions and poor myofiber longevity. Atypical myogenic cells seen in Duchenne muscular dystrophy cultures differed ultrastructurally from normal myoblasts in having a smaller population of free ribosomes and polyribosomes, prominent rough endoplasmic reticulum, and abundant intermediate filaments. The dystrophic myofibers that had reached relative maturity always exhibited a poorly developed contractile apparatus in contrast to structurally well-defined normal myofibers. It is inferred that the impaired myogenesis observed in Duchenne muscular dystrophy cultures results primarily from defective fusion involving atypical myogenic cells.

Adolescent↗
PubMed1983

The permissive role of catecholamines in the pathogenesis of hamster cardiomyopathy.

It was previously shown that beta-adrenergic blockers exert a protective action on the development of heart necrotic changes in cardiomyopathic hamsters. To further investigate the possible role of catecholamines in the pathogenesis of the hamster hereditary cardiomyopathy, the ventricular adrenergic nerve terminals were visualized by fluorescence histochemistry, and NE uptake and turnover were determined after i.v. injection of labeled NE. It was found that the fluorescent nerve endings strongly proliferate with the occurrence of heart necrotic changes. With healing of the myocardial lesions, the difference between control and myopathic hearts is less apparent, and NE nerve endings are literally absent in the terminal stage of the disease. There was a marked increase in NE uptake during the necrotic stage and, at the same time, a considerable rise in elimination rate constant with a maximum level at terminal state, suggesting that the NE turnover is related to the progression of the disease. In light of the present findings, it can be surmised that NE plays a permissive role in the genesis of the hamster disease by promoting the heart necrotic changes.

Animals↗
PubMed1982

Hereditary polymyopathy and cardiomyopathy in the Syrian hamster. I. Progression of heart and skeletal muscle lesions in the UM-X7.1 line.

The Syrian hamster polymyopathy is a hereditary disease, transmitted by an autosomal recessive gene, involving the heart and the entire musculature. The chronology of the pathologic events in the myocardium and skeletal muscle has been investigated in UM-X7.1 myopathic hamsters aged 0-250 days. A phasic pattern in the progression of the disease process was evident. Microscopic necrotic changes in the heart were visible prior to or at 50 days of age with increasing severity until 100 days of age and subsidence thereafter. More than 50% of the animals died before 250 days of age with signs of cardiac failure. The intensity and extent of myocardial calcific changes together with scar formation were determinant factors in curtailing the survival of animals. Changes in serum creatine kinase (CK) activity followed a phasic pattern similar to the progression of the myopathic disease. Because of the disparity of disease manifestations between the different myopathic hamster lines, it is essential to consider the time course of the heart and skeletal muscle microscopic changes when evaluating the severity of the hamster polymyopathy.

Animals↗
PubMed1982

Hereditary polymyopathy and cardiomyopathy in the Syrian hamster. II. Development of heart necrotic changes in relation to defective mitochondrial function.

The mitochondrial oxidative phosphorylation, calcium and magnesium contents, and swelling-contraction activity were investigated in relation to the progression of the hereditary hamster cardiomyopathy. The assessment was made in animals between 22 and 232 days of age, which were divided into 7 groups according to stage of disease. In 24-day-old hamsters prior to development of heart necrotic changes, the membrane permeability of isolated mitochondria was altered. In 50-day-old animals, at a stage of disease when myocardial cells undergo degeneration, a defect of oxidative phosphorylation resulting from an increase in mitochondrial calcium was demonstrated. With culmination of the heart necrotic changes, at close to 100 days of age, mitochondrial dysfunction and calcium overload were maximal. There was a transient improvement during the healing stage, but the situation deteriorated with the occurrence of circulatory failure. Since the mitochondrial respiratory pattern and calcium overload parallel the cardiac degeneration, it is inferred that the cell energy depletion is a functional consequence of an abnormal calcium influx.

Animals↗
PubMed1982

Impaired muscle differentiation in hamster hereditary polymyopathy: A study in explant cultures.

Muscle tissue cultures from normal and myopathic neonate hamsters were established by a new explant technique and their morphology compared. Many abnormal myogenic cells fused in early myopathic cultures. As the myopathic cultures became older, an abnormal contractile apparatus, which displayed reduced spontaneous contractility as compared to controls, was evident. These findings in explant cultures provide further support for the myogenic basis of hereditary hamster myopathy and demonstrate the usefulness of the explant technique for comparative studies of in vitro myogenesis.

Animals↗
PubMed1980

Terminal motor innervation in myopathic hamsters.

Terminal motor innervation and the histochemical profile of muscle fibers were investigated, before and after sciatic nerve crushing, in 1- to 150-day-old myopathic hamsters. The observed morphologic abnormalities in terminal motor innervation were of varying degree prior to the nerve injury. These abnormalities were found in close proximity to lesions of the myofibers, and became more pronounced with age and the progression of the disease process. Collateral ramification of healthy axons occurred in hamsters of 120 days of age with reinnervation of damaged muscle fibers. When submitted to sciatic nerve crushing, myopathic hamsters showed an ability to regenerate and reinnervate the subneural apparatuses. The regenerative process in these animals was essentially the same as in normal, sciatic nerve-crushed hamsters. Thus, it was concluded that the morphologic changes in terminal motor innervation were secondary to muscle cell degeneration.

Aging↗
PubMed1980

Atypical myogenesis in hamster hereditary polymyopathy. An in vitro study.

An in vitro study of dissociated muscle cells from normal and myopathic neonatal hamsters was undertaken in an attempt to characterize, by morphological means, a possible abnormal myogenesis in the hereditary polymyopathy of the hamster. There were fundamental structural differences between mononucleated muscle cells before and during myogenic cell fusion, as well as between multinucleated myotubes of normal and myopathic cultures. With reference to conventional morphologic features of normal muscle cultures, more numerous "atypical" foci of myogenesis, some with a bizarre appearance, were seen in myopathic hamsters, as compared to the controls. Because the cultured cells developed in the absence of vascular and neurogenic influences, a myogenic origin may be inferred for the different structural base found in vitro in the myopathic hamster.

Animals↗
PubMed1979

Generalized giant axonal neuropathy-a case with features of Fazio-Londe disease.

We present the 8th case so far published of generalized giant axonal neuropathy. Many features of the neurological picture of this 8 year 8 month old boy were suggestive of progressive bulbar paralysis of childhood. Muscle and sural nerve biopsies disclosed typical nodular axonal swellings measuring between 10--29 nm. Ultrastructure of the inflated portions of the axon consisted almost exclusively of 10 nm filaments. Normally appearing constituents were found in the non-dilated portions of the axons with this particularity that glycogen and mitochondria were aggregated. Previous clinical and pathological evidence indicates that this rare disorder not only affects the peripheral nerves but also the whole CNS. Our case differs from the others reported in literature by its rapidly deteriorating course and by the prominent involvement of some brain-stem motor functions; we offer the theory that a link might be implicated between this entity and Fazio-Londe disease.

Axons↗