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Biomedical subjects

H B Sarnat

Publications and source records attributed to H B Sarnat.

At least 73 records · Page 4Linked to original sources
PubMed1985

The brain of the planarian as the ancestor of the human brain.

The planarian is the simplest living animal having a body plan of bilateral symmetry and cephalization. The brain of these free-living flatworms is a bilobed structure with a cortex of nerve cells and a core of nerve fibres including some that decussate to form commissures. Special sensory input from chemoreceptors, photoreceptor cells of primitive eyes, and tactile receptors are integrated to provide motor responses of the entire body, and local reflexes. Many morphological, electrophysiological, and pharmacological features of planarian neurons, as well as synaptic organization, are reminiscent of the vertebrate brain. Multipolar neurons and dendritic spines are rare in higher invertebrates, but are found in the planarian. Several neurotransmitter substances identified in the human brain also occur in the planarian nervous system. The planarian evolved before the divergence of the phylogenetic line leading to vertebrates. This simple worm therefore is suggested as a living example of the early evolution of the vertebrate brain. An extraordinary plasticity and regenerative capacity, and sensitivity to neurotoxins, provide unique opportunities for studying the reorganization of the nervous system after injury. Study of this simple organism may also contribute to a better understanding of the evolution of the human nervous system.

Animals↗
PubMed1985

A fluorochromic stain for nucleic acids to demonstrate submucosal and myenteric neurons in Hirschsprung's disease.

Acridine orange, a rapid and technically simple fluorochromic stain of nucleic acids, was applied to sections of 18 specimens of resected distal colon in infants with Hirschsprung's disease. Neurons were readily identified in the submucosal and myenteric plexuses of normal ganglionic segments because of their intense orange cytoplasmic fluorescence of ribonucleic acid (RNA) that contrasted with the pale green of the smooth muscle and connective tissue. This technic, which may be applied to both frozen and paraffin-embedded sections, is a useful adjunct in the confirmation of aganglionic segments of bowel wall.

Acridine Orange↗
PubMed1985

[Acridine orange: a fluorochrome of nucleic acids for the study of muscle and nerve cells].

Acridine orange renders nucleic acids fluorescent when forming complexes with them: D.N.A. is coloured luminous yellow while R.N.A. is a brilliant orange. Its application to sections of muscle biopsies permits the identification of certain muscle fibres, recognized by their bright orange fluorescence which contrasts with the pale green of mature, normal myofibrils in three specific situations: denervation, regeneration following injury, and the rapid growth and maturation of fetal muscle. Moreover, myopathic nonregenerative atrophy, as well as histochemical type-specific atrophies, do not exhibit this same orange fluorescence. Because neurons, particularly motor neurons, contain large amounts of R.N.A. (by contrast with glial cells which have very little) the application of acridine orange in the central nervous system might help in understanding the development of the fetal brain, the evolution of some neurologic diseases, and the maturation of brain tumors. Since the technique does not require the exclusive use of frozen tissues, but also may be applied to formalin-fixed tissue in paraffin sections, it is well adapted to the study of tissue obtained at autopsy.

Acridine Orange↗
PubMed1985

[Does the brain influence the muscular development of the human fetus? Evidence in 21 cases].

The importance of suprasegmental cerebral influence on developing human fetal muscle is less well understood than the control of histochemical differentiation of muscle by the motor neuron. Muscle biopsies of 21 hypotonic infants and children with nonprogressive congenital lesions of the cerebellum and/or brainstem were studied by histochemical methods. Two neonates who died with severely dysplastic brains and no descending motor tracts had normal muscle. The others, particularly those with cerebellar hypoplasia, had delayed muscle maturation, selective predominance of type I or II muscle fibres or disproportion in fibre sizes. It is concluded that the motor unit is capable of developing normally without suprasegmental influence, but that an abnormal balance of descending impulses may alter histochemical differentiation of fetal muscle. The small 'subcorticospinal' pathways arising in the brainstem probably are more influential than the larger corticospinal tract because of later myelination in the latter. The muscle biopsy thus serves to provide evidence of suprasegmental disease in infantile hypotonia.

Brain↗
PubMed1984

Hypothesis: Phylogenetic diseases of the nervous system.

A few human diseases may be viewed from a phylogenetic perspective. Some metabolic or degenerative diseases selectively affect recently evolved or exclusively mammalian structures of the brain and spare the older structures. Examples include Krabbe's leukodystrophy, olivopontocerebellar atrophy, Friedreich's ataxia, Pick's disease, and Leber's optic atrophy. Some pathologic conditions in man are similar to normal anatomy in other species, although the mechanisms may differ. Congenital muscle fiber-type disproportion in rodents, Dandy-Walker cyst in birds, and agenesis of the corpus callosum in marsupials are representative of this category. Loss of basal dendritic spines from pyramidal cells in Pick's disease is reminiscent of certain large neurons normally found in the cortex of reptiles. Changes in metabolism in the evolution of mammals in general and of man in particular may explain some aspects of 'phylogenetic diseases'. Some potential examples are the shift from predominantly phospholipids to galactolipids in myelin composition as mammals evolved, and the greater toxicity of cyanide and other poisons of oxidative metabolism in mammals than in other vertebrates because of less reliance on anaerobic metabolism as an alternative energy source.

Agenesis of Corpus Callosum↗
PubMed1983

Mitochondrial myopathy of cerebro-hepato-renal (Zellweger) syndrome.

The muscles of four infants with cerebro-hepato-renal (Zellweger) syndrome were studied during life and/or at necropsy. A mitochondrial myopathy was demonstrated, similar to mitochondrial alterations demonstrated in liver and brain in this disease. Muscle fibers with red-staining subsarcolemmal aggregates were identified with Gomori trichrome stain in two cases. Subsarcolemmal and intermyofibrillar zones of increased concentrations of NADH-TR, SDH, and cytochrome-c-oxidase activity were demonstrated histochemically in all four cases. Degenerative and cytoarchitectural changes in muscle fibers were not found. Ultrastructural studies showed large aggregates of mitochondria and increased lipid in the subsarcolemmal and intermyofibrillar spaces. Degenerative changes in mitochondria and lipid also were demonstrated, but paracrystalline inclusions were not seen. The distribution of these changes was not uniform between patients or between different muscles in the same patient. The diaphragm was affected more severely than proximal or distal muscles of the extremities. Direct involvement of muscle mitochondria in this disease may interfere with energy metabolism and contribute to the clinical findings of hypotonia, weakness, and respiratory insufficiency. The muscle biopsy with histochemistry and electron microscopy may be used as a diagnostic adjunct in suspected cases, but the variation encountered dictates dictates caution in the interpretation of negative findings.

Brain Diseases↗
PubMed1983

The discovery, proof and reproof of neurosecretion (Speidel, 1917; Scharrer and Scharrer, 1934).

Seventeen years before the Scharrers demonstrated neurosecretory activity of neurons within the brains of vertebrates and invertebrates and convinced the scientific world of the existence of a neuroendocrine system, Carl Caskey Speidel (1917) had identified glandular neurons in the spinal cord of the skate, postulated a neurosecretory function, and performed experiments to prove his hypothesis. The correct conclusions that he formulated from morphologic observations were not believed by biologists until 'proved' by the Scharrers, who acknowledged his pioneering contributions. The Scharrers studied many species and even demonstrated neurosecretion in nemertine worms, now believed to be closely related to the ancestors of all vertebrates. Evolutionary theorists had speculated on neuroglandular function as early as 1900, and the contribution of comparative neuroanatomists to this field have resulted in a major medical advance.

Animals↗
PubMed1982

Lipid storage myopathy in infantile Pompe's disease.

An infant died at 8 months of age with a history of developmental regression, hypotonia, severe weakness, cardiomegaly, congestive heart failure, and hepatomegaly. A diagnosis of Pompe's disease (glycogenosis type II) was established by muscle biopsy at 5 months of age. Vacuolar myopathy involved muscle fibers of histochemical type I more than type II. Many vacuoles were filled with glycogen. In addition, increased amounts of neutral lipid were demonstrated by oil red O stain, electron microscopy, and quantitative analysis. Acid alpha-1,4-glucosidase activity was demonstrated to be deficient. Biochemical studies failed to determine the cause of the lipid accumulation, but demonstrated a low total concentration of carnitine in the muscle (6.37 nmole/mg of protein), associated with elevated activities of carnitine palmityl-transferase and palmityl-coenzyme A dehydrogenase. Palmityl-coenzyme A synthetase activity was in the normal range.

Carnitine O-Palmitoyltransferase↗
PubMed1982

Heterotopic growth of dysplastic cerebellum in frontal encephalocele in an infant of a diabetic mother.

An infant of a diabetic mother lived 13 days after birth. She had a small dysplastic 12.6 gm. brain, partly forming a frontal encephalocele. The uncleaved forebrain contained a mass of poorly organized heterotopic cerebellar cortex. The cerebellum itself had normal lamination, but was small and continuous with the dysplastic tissue. The ventricular system was absent except for a few midline ependymal rosettes, and the cerebral cortex was not developed. The cerebellar dysplasia resembled a proliferative and invasive lesion by its rostral extension.

Brain↗
PubMed1981

Congenital muscle fiber-type disproportion in Krabbe's leukodystrophy.

Progressive spasticity, blindness, loss of skills, and neuropathy developed in a 4.5-month-old boy. When examined at 13 months, galactocerebrosidase and galactosylceramide-beta-galactosidase activities were deficient in leukocytes. Intramuscular nerves and a sural nerve biopsy specimen showed loss of nerve fibers, interstitial fibrosis, and axonal degeneration, rather than the segmental demyelination that predominates in most cases. A muscle biopsy specimen showed congenital muscle fiber-type disproportion (CMFTD). This case confirms a previous report of CMFTD in Krabbe's disease and supports a neurogenic mechanism as the basis for CMFTD.

Child, Preschool↗
PubMed1981

Neonatal myotubular myopathy: neuropathy and failure of postnatal maturation of fetal muscle.

The natural course of the pathologic features in striated muscle was studied in a full-term infant with myotubular myopathy. At 5 days of age a muscle biopsy revealed that more than 90 percent of muscle fibers fulfilled histologic, histochemical and electron microscopic criteria of fetal myotubes. The infant died unexpectedly at 9 months of age from spontaneous rupture of a multifocal cavernous hemangioma of the liver. Postmortem examination revealed that progressive maturation of the fetal muscle had not occurred postnatally, and more than 90 percent of myofibers were still apparent myotubes. This maturational arrest was generalized to all striated muscles. The only changes detected since the neonatal period were hypertrophy of the small population of large fibers, but with minor cytoarchitectural alterations, and loss of the incomplete histochemical differentiation with ATPase stains or dedifferentiation not attributed to postmortem diffusion. Involvement of the gubernaculum testis accounted for the undescended testicles. The brain and spinal cord appeared normal. Evidence of degenerating and regenerating axons in the sciatic nerve suggested that the etiology of this maturational arrest of fetal muscle may be neurogenic.

Aging↗
PubMed1980

Human cerebellar hypoplasia: a syndrome of diverse causes.

Seven children had congenitally small cerebella. Perinatal asphyxia was not a factor. Clinical signs in infancy were generalized muscular hypotonia, delayed development, truncal titubation, and intention tremor. Most had fixation nystagmus and esotropia. Three had seizures and an abnormal EEG. Pneumoencephalography in each case revealed a small cerebellum with prominent folia, large fourth ventricle, wide vallecula, large cisterna magna, and normal lateral and third ventricles. A computerized tomography scan in one case showed similar findings. One patient had an absent corpus callosum. One patient died at 2 1/2 years. The cerebellar hemispheres and vermis were small. Granular cells were absent throughout. Purkinje's cells were preserved, but had dendritic swellings with radiating fibrils. Cerebellar, pontine, and inferior olivary nuclei showed mild neuronal loss. The clinical and pathologic findings resemble those of animal models of cerebellar hypoplasia produced by fetal exposure to certain viruses, toxins, or repeated low doses of radiation. Cerebellar hypoplasia is a clinical syndrome of several causes, but with many symptoms and signs in common.

Cerebellar Diseases↗
PubMed1980

Low efficacy radiography of children.

Radiographic procedures performed at a 100-bed pediatric hospital were reviewed jointly by a radiologist and the primary physician staff. The reviewers judged several procedures to be performed unnecessarily, with undue patient risk or cost. Low efficacy examinations were divided into two categories: (1) low-yield examinations with significant gonadal radiation as well as significant cost, and (2) low-yield examinations with low gonadal radiation but significant cost. A joint policy recommendation was then delivered to the house staff concerning appropriate indications for the performance of these low-yield procedures. This active review process is submitted as a model for other medical facilities that seek to reduce risk and cost to the pediatric patient.

Angiography↗
PubMed1979

Cerebral embryopathy in late first trimester: possible association with swine influenza vaccine.

An infant girl was born with cerebral malformations characterized by developmental arrest late in the first trimester of gestation. These features included persistent pontine flexure, cerebellum developed only around the rhombic lip, failure of migration of inferior olive, absence of basis pontis and of corticospinal and corticopontine tracts, and agenesis of olfactory bulbs. The cerebral cortex was thin and poorly laminated, and primary and secondary sulci had failed to form. The choroid plexus contained vascular malformations, hemorrhages, and infarcts. The leptomeninges contained foci of primitive mesenchyme. The mother had received an inoculation of swine influenza vaccine six weeks after conception, followed by a 2-week illness. The temporal relation to the timing of the cerebral malformation suggests a teratogenic effect of the vaccine, but may have been coincidental.

Adult↗
PubMed1979

Diagnostic value of histochemistry in embryonal rhabdomyosarcoma.

Embryonal rhabdomyosarcomas from the nasopharynx of two children were examined by histochemical methods commonly applied to muscle biopsies. These stains included nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR), succinate dehydrogenase (SDH), PAS, PAS-diastase, myophosphorylase, calcium-mediated adenosine triphosphatase (ATPase) preincubated at high and low pH, and oil red O. Myofibrils were easily identified with ATPase and blood vessel walls were also stained. NADH-TR clearly showed longitudinal and cross-striations that were not seen with H&E or PTAH stains. The modified Gomori trichrome stain additionally contributed to the recognition of myofibrils. Some techniques of muscle histochemistry applied to fresh frozen sections of tumor tissue may provide evidence of muscular differentiation in otherwise poorly differentiated sarcomas for a more accurate diagnosis of rhabdomyosarcoma.

Child, Preschool↗
PubMed1979

Effects of tenotomy on the muscle of the turtle: a histochemical study.

Tenotomized turtle muscles exhibited some changes similar to those found in mammalian tenotomized muscles. These changes included presence of small rounded and angulated fibres with high oxidative reaction, acute necrosis of fibres with degenerative changes, perivascular cellular reaction, phagocytosis and the atrophy of all 3 types of fibres. In contrast to mammalian tenotomized muscles, no decrease in PAS positive material and phosphorylase activity was noticeable. Also, the central core fibres and nemaline rods were absent in tenotomized turtle muscles.

Achilles Tendon↗
PubMed1978

Alteration of developing and adult rat muscle membranes by zuclomiphene and other hypocholesterolemic agents.

The present study presents evidence for a third hypocholesterolemic drug, zuclomiphene, being able to induce an experimental myotonic condition. Other drugs used singly or in combination were AY-9944, Triparanol and 20, 25-diazacholesterol. It has also been demonstrated for the first time that experimental myotonia can be induced in developing rats as well as adults. Developing rats received the initial intraperitoneal injections of drug at 5 days of age and were examined at 50 days of age. Adult rats were treated for 5 weeks. Two injections were given per week. Positive electromyography findings were observed in the developing and adult animals receiving 20, 25-diazacholesterol and zuclomiphene. The electromyography data of the other regimens of treatment were equivocal with regard to myotonia. Histological, histochemical, and electron microscopic examination of the muscle demonstrated no important changes. estimation of sterol composition showed that desmosterol was a major sterol in muscle after 20, 25-diazacholesterol or zuclomiphene treatment, thus furthering the concept that it is desmosterol in the muscle membrane, and not the drug, that is responsible for the myotonic condition.

Animals↗