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Biomedical subjects

S M Chou

Publications and source records attributed to S M Chou.

At least 91 records · Page 5Linked to original sources
PubMed1977

Satellite cells and muscle regeneration in diseased human skeletal muscles.

By virtue of the lanthanum nitrate staining technique applied to biopsied muscle we are able to demonstrate interaction between satellite cells and parent myofibers, as well as development of premyocytes from activated satellite cells. The process of regeneration in diseased muscle appears to differ from that described in experimental myogenesis. Transformation of activated satellite cells to two types of premyocytes in the process of muscle regeneration seems to rely primarily on the state of innervation and recovery rate of the parent cell after injury. Activated satellite cells are characterized morphologically by proliferation of caveolae, first on the parent fiber side, and early T-tubule and myofilament formation and central displacement. In diseased human muscle the satellite cells appear to play significant roles in muscle regeneration both as a source of reinforcement for failing metabolism in the parent cell and as potential replacements for the necrotic segment of the parent cell. This study also demonstrates that the satellite cells are capable of developing into independent myocytes which may fuse with or replace the parent cell, dependent upon the type and extent of the injury sustained. Abnormal fusion among premyocytes or with their parent fiber, resulting in formation of split-or ring-fibers, becomes conceivable when both innervation and recovery from the injury of the parent cell are delayed. Thus, myotube formation, characteristic of usual myogenesis, seldom takes place in the regenerative process instituted by satellite cells in diseased human skeletal muscles.

Humans↗
PubMed1977

Animal cell mutants defective in sterol metabolism: a specific selection procedure and partial characterization of defects.

By using a chemically defined medium, a general and highly specific procedure was devised to select for mutant cells with less abundant or structurally altered sterol in their surface membranes. Within a certain concentration range, the polyene antibiotic filipin was shown to kill only cells with normal (as opposed to decreased) membrane sterol levels. Sterol-requiring derivatives of LM cells were isolated by chemical mutagenesis, filipin treatment, and cloning followed by replica plating in soft agar. Mutants (S1 and S2) are described which, when compared to normal cells, show decreased synthesis of demosterol in vivo from acetate and mevalonate relative to cell number or to fatty acid synthesis. When exogenous sterol is supplied, mutants S1 and S2 grow normally in suspension culture. However, when deprived of sterol supplement, mutant S1 grows slower than wild type cells and mutant S2 lyses within one to two generations. Gas/liquid chromatography revealed that the mutants contained a normal spectrum of fatty acids including unsaturated fatty acyl groups but, unlike wildtype cells, they have less abundant (mutant S1) or no (mutant S2) desmosterol in either the presence or absence of exogenous cholesterol. In vitro experiments with mevalonate as the substrate suggest that the defect in both mutants is in a demethylation reaction subsequent to lanosterol synthesis. The selection method developed here may permit the isolation of mutants with defective membrane incorporation of sterols and other polyisoprenoids as well as defective synthesis of these compounds.

Acetates↗
PubMed1977

Mycoplasma-induced hydrocephalus in rats and hamsters.

Mycoplasma pulmonis, a pathogen of the respiratory tract in rats, was inoculated intracerebrally into neonate rats and hamsters to determine if it would induce lesions in the ependyma. Hydrocephalus was induced in 116 of 120 rats and in 23 of 28 hamsters. The severity of hydrocephalus was greater in the rats than in the hamsters. Hydrocephalus induction occurred only subsequent to inoculation of viable M. pulmonis. At 2 weeks of age, rats became refractory to induction of hydrocephalus. Light microscopy indicated that the hydrocephalus was communicating without an inflammatory response in the ventricles and meninges. Preliminary electron microscopy revealed that amorphous material covered portions of the ependymal surface and that cilia were sometimes matted together. It was suggested that the hydrocephalus was due to ciliary dysfunction or to an imbalance of cerebrospinal fluid secretion and absorption. This M. pulmonis-induced hydrocephalus may be a useful model for elucidating the pathogenesis of certain types of congenital hydrocephalus in humans.

Aging↗
PubMed1976

Empty sella syndrome secondary to intrasellar cyst in adolescence.

A 15-year-old boy had growth failure and failure of sexual development. The probable onset was at age 10. Endocrine studies showed hypopituitarism with deficiency of growth hormone and follicle-stimulating hormone, an abnormal response to metyrapone, and deficiency of thyroid function. Luteinizing hormone level was in the low-normal range. Posterior pituitary function was normal. Roentgenogram showed a large sella with some destruction of the posterior clinoids. Transsphenoidal exploration was carried out. The sella was empty except for a whitish membrane; no pituitary tissue was seen. The sella was packed with muscle. Recovery was uneventful, and the patient was given replacement therapy. On histologic examination,the cyst wall showed low pseudostratified cuboidal epithelium and occasional squamous metaplasia. Hemosiderin-filled phagocytes and acinar structures were also seen. The diagnosis was probable rupture of an intrasellar epithelial cyst, leading to empty sella syndrome.

Adolescent↗
PubMed1976

JC Papovavirus in progressive multifocal leukoencephalopathy.

Brain tissue from seven patients with progressive multifocal leukoencephalopathy was tested for the presence of papovaviruses. JC virus, ahuman papovavirus, was identified in all seven cases. Virus was isolated in tissue culture from extracts from each of four patients and was detected by immunofluorescence in sections from the other three. The new osolates were indistinguishable from the prototypical JC strain serologically and in all biological characteristics examined. Thus JC virus has, to date, been associated with 20 cases of progressive multifocal leukoencephalopathy.

Adult↗
PubMed1976

Isolation and characterization of two new herpes-like viruses from capuchin monkeys.

Two herpes-like viruses were isolated from capuchin monkey (Cebus apella) brain and (Cebus albifrons) spleen cell cultures, respectively. Both isolates induced similar cytopathic effects consisting of rounded and ballooned cells in the original monkey cell cultures and in a wide range of permissive cell types. Neutralizing antibody to each virus was present in serum from the capuchin monkey from which it was isolated, but the two viruses did not cross-react by neutralization. Fluorescein isothiocyanate conjugates of hyperimmune rabbit serum to one of the isolates showed an antigenic cross relationship between the two isolates. By electron microscopy, herpes-like virus particles were observed in the nucleus and cytoplasm of infected human diploid fibroblast cell cultures. Virus-infected cell cultures stained with acridine orange revealed small deoxyribonucleic acid-containing intranuclear inclusion bodies. Both viruses were inhibited by 5-fluorodeoxyuridine and inactivated by chloroform or exposure to 56 degrees C for 30 min. Antisera prepared against 16 prototype herpesviruses and cytomegaloviruses did not neutralize approximately 100 50% tissue culture infective doses of either capuchin isolate. Neutralizing antibody to the capuchin isolates was detected in sera from 8 of 17 capuchin monkeys but not in sera from 16 humans, 15 chimpanzees, and 10 spider, 6 rhesus, and 5 squirrel monkeys.

Animals↗
PubMed1976

Myasthenia gravis. Current concepts.

The prevalent theory of the past two decades, that the defect in myasthenia gravis (MG) is the packaging of achetylcholine (Ach) into smaller quantal units, has recently been revised. The current theory is based on (1) electron microscopical studies of motor end plates in patients with MG; (2) radioisotope study with alpha-bungarotoxin of postsynaptic membrane Ach receptor (Ach R) sites; (3) sensitization of rabbits with the use of purified Ach R from the electric eel, inducing experimental autoimmune myasthenia gravis (EAMG); (4) detection of antibodies to the Ach R in patients with MG by radioimmunoassay; and (5) apparent induction of MG in mice by passive transfer of immunoglobulin from patients with MG. Thus, the emphasis on pathogenesis of MG is now placed on an autoimmune process involving Ach R in the subsynaptic membrane of neuromuscular junctions.

Acetylcholine↗
PubMed1975

Familial cerebral sarcomas.

Four cases of cerebral fibrosarcomas occurring in two families are reported. To our knowledge, no similar cases have been reported. Evidence that a heritable factor is involved in the genesis of some brain tumors is suggested by these cases.

Aged↗
PubMed1975

Fusariosis, myasthenic syndrome, and aplastic anemia.

Fusarium, a fungus, produces a potent mycotoxin that, when ingested with contaminated cereal grains, produces a serious illness in man called alimentary toxic aleukia (USSR) and Akakabi-byo (Japan). The illness includes gastrointestinal symptoms and weakness and if ingestion of Fusarium contaminated grain persists, culminates in aplastic anemia. A 66-year-old woman had Eaton-Lambert syndrome and a clinical course similar to alimentary toxic aleukia. Several months before her death, pancytopenia, initially thought guanidine-induced, developed and progressed to aplastic anemia despite discontinuation of guanidine 2 1/2 months before death. Autopsy showed numerous granuloma in the liver, spleen, esophagus, and cecum from which Fusarium oxysporum was isolated. Although the unique finding of systemic fusariosis may relate to altered host resistance terminally, a causal relationship with her defect of neuromuscular transmission and/or aplastic anemia is a distinct possibility.

Aged↗
PubMed1975

Progressive multifocal leukoencephalopathy with 10-year survival in a patient with nontropical sprue. Report of a case with unusual light and electron microscopic features.

A 46-year-old man with nontropical sprue had anemia and hypoproteinemia for several years, until his condition was diagnosed and treated with dietary measures. Within a year after the diagnosis, progressive multifocal leukoencephalopathy developed, and the patient had a slightly fluctuating chronic downhill course until he died 10 years later. It is postulated that this patient's immune deficiency was related to his malabsorption syndrome and hypoglobulinemia, and the course became unusually protracted (longest reported course in the American literature) because of restoration of plasma protein levels. Autopsy showed the classic findings of progressive multifocal leukoencephalopathy, with much tissue loss of subcortical white matter and active perivascular inflammatory foci with numerous eosinophilic granulocytes. On electron microscopy, oligodendrocyte nuclei and cytoplasm were crowded with virions, but many myelin sheaths invested by severely infected oligodendrocytic processes were remarkably well preserved. This fact would argue against a direct cause-and-effect relationship between infection of oligodendrocytes and myelin breakdown in progressive multifocal leukoencephalopathy. The likelihood of an autoimmune mechanism at work in this disease is suggested, and the role of eosinophils and other cells in such process is considered.

Astrocytes↗
PubMed1975

Unusual presentation of a choroid plexus papilloma.

An unusual case of a choroid plexus papilloma which completely isolated the right temporal and occipital horns from the remainder of the ventricular system is presented. The tumor secreted large quantities of cerebrospinal fluid and also bled into this obstructed cavity. A gross total removal was accomplished.

Cerebral Ventricle Neoplasms↗
PubMed1974

Ependymal cyst of the thoracic spinal cord.

A unique case of an ependymal cyst on the anterior aspect of the thoracic spinal cord in a woman aged 68 years is described. Clinical signs were precipitated by trauma. Recovery of function, while incomplete, was remarkably good after extirpation of the cyst.

Aged↗