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H B Sarnat

Publications and source records attributed to H B Sarnat.

At least 55 records · Page 3Linked to original sources
PubMed1989

Unimpaired RNA synthesis in neurons and epithelial cells in a freshwater leech exposed to the organophosphate insecticide chlorpyrifos.

Chlorpyrifos (Dursban) is an organophosphate insecticide widely used mainly for control of mosquito larvae. This study used the dominant freshwater leech Nephelopsis obscura as a representative aquatic invertebrate to test toxicity of chlorpyrifos on a nontarget species. RNA synthesis in neurons of the cerebral ganglion, epithelial cells of the intestine, and the tegument of small immature (50-70 mg) and large mature (300-400 mg) N. obscura was examined histochemically with acridine orange fluorochrome after exposure to chlorpyrifos in concentrations of 16, 32, 64, 128, and 144 ppb for as long as 6 weeks. The maximum environmental concentration of this insecticide in lake water, when used properly, is 4.25 ppb. There was no mortality, and no behavioral changes were observed in experimental animals, except for transient curling and cutaneous mucus secretion at the highest concentrations of chlorpyrifos. No pathological changes were observed in the intensity of RNA fluorescence or in the distribution of RNA within the cytoplasm of neurons or epithelial cells in any specimens, unlike N. obscura exposed to anoxia, hyperoxia, or salinity. Chlorpyrifos in the concentrations studied does not appear to adversely affect nucleic acid metabolism in N. obscura.

Animals↗
PubMed1989

Acridine orange-RNA fluorescence of maturing neurons in the perinatal rat brain.

Cytoplasmic RNA was demonstrated in neurons of the developing rat brain using acridine orange (AO) as a histochemical marker. Fetuses of 18 days and postnatal rats of 1, 7, 14, and 21 days as well as adults several months old were studied. Neuroblasts of the germinal matrix exhibited minimal or no orange-red AO-RNA fluorescence, but immature nerve cells in migration within the cerebral hemispheres of the rat showed a weak but definite orange colour. This finding contrasts with the absence of AO-RNA fluorescence in migrating human neuroblasts. Neurons of the neocortical plate showed uniformly strong fluorescence. In the hippocampus, the most pronounced increase in AO-demonstrated RNA was in pyramidal and granule cells during the first postnatal week. The cerebellum showed a paradoxically stronger fluorescence of granule cells in the 18-day fetus than at birth, and almost no AO-RNA fluorescence of granule cells at 21 days of age or in adults. Motor neurons showed the strongest fluorescence of all neurons. It is likely that the increase in cytoplasmic RNA in neurons corresponds to the onset of neurotransmitter biosynthesis, but transitory fetal neuropeptides may explain stronger fluorescence of some neurons in young individuals. The reliable and simple AO method provides a supplementary means of studying one aspect of neuronal maturation.

Acridine Orange↗
PubMed1989

Fluorescence histochemistry of RNA in human pituitary adenomas.

Acridine orange (AO)-RNA fluorescence was studied histochemically in 9 normal human pituitary glands, in 26 secretory and nonsecretory pituitary adenomas, and in a dysgerminoma. Six adenomas showing immunoreactivity for prolactin showed intense orange-red cytoplasmic fluorescence; 6 other tumours exhibiting immunoperoxidase activity of growth hormone showed less intense AO-RNA fluorescence, and 5 adrenocorticotropic hormone-containing adenomas showed still weaker orange fluorescence. Among the chromophobe adenomas without immunoreactivity for secretory products, 5 had uniformly very weak AO-RNA fluorescence, while in 4 other a few scattered cells with strong AO-RNA fluorescence were detected among the majority of weakly fluorescent cells. The pituitary dysgerminoma contained many cells with strong AO-RNA fluorescence. Electron microscopy of these cases showed good correlation of cytoplasmic concentration of ribosomes with AO-RNA fluorescence of the adenomas. AO is useful as an inexpensive, simple supplementary stain for frozen or paraffin sections of pituitary tumours to infer secretory activity as a correlate of RNA concentration and to demonstrate a secretory potential in some cells of hormonally inactive tumours.

Acridine Orange↗
PubMed1989

Effects of anoxia, hyperoxia, and salinity on neurons in the leech Nephelopsis obscura (Erpobdellidae): RNA redistribution by fluorescence histochemistry.

The histochemical distribution of cytoplasmic RNA in ganglion cells of the freshwater leech Nephelopsis obscura has been studied using the fluorochrome acridine orange as a marker of nucleic acids. Two series of experiments, employing 50 adult animals, involved changes in oxygen tension in the water and changes in salinity. Normal leech neurons exhibit finely granular orange fluorescence uniformly distributed throughout the cytoplasm, with a perinuclear ring of especially strong fluorescence. After exposure to anoxic (0% O2), hypoxic (20% O2), or hyperoxic (200% O2) conditions at 20 degrees C for 1-15 days, the orange cytoplasmic fluorescence is no longer uniformly distributed; the redistribution is generally toward the periphery, leaving the perinuclear zone without RNA fluorescence, but irregular zones of cytoplasm devoid of RNA also occur not as a gradient. Leeches exposed to salinity of, or greater than, 2.5 ppt for 15 days exhibit similar changes. These alterations are confirmed by electron microscopy. Seasonal fluctuations in oxygen tension and salinity of lake water affect the distribution and abundance of organisms. The acridine orange method provides one measure of stress to the nervous system in freshwater invertebrates that might be applicable to ecological studies as well as to metabolic studies of individual animals.

Acridine Orange↗
PubMed1989

Do the corticospinal and corticobulbar tracts mediate functions in the human newborn?

Unlike the numerous dispersed bulbospinal pathways that are already well myelinated at term, the more compact corticospinal and corticobulbar tracts are only beginning their myelination cycle in late gestation and do not complete it until two years of age. During this same period, these pathways also develop extensive ramification of terminal axonal segments, growth of collateral axons, and proliferation of synapses. Despite their immaturity in the full-term human newborn, several proposed functions may be attributed to the descending pathways from the neonatal cerebral cortex: a) a contribution to the differential development of passive muscle tone and resting postures; in general they function as an antagonist to the "subcorticospinal pathways" in mediating proximal flexion and distal extension, except for the rubrospinal tract which is probably synergistic with the corticospinal tract; b) enhancement of tactile reflexes originating in the brainstem and spinal cord, including suck and swallow; c) relay of epileptic activity of cortical origin; d) inhibition of complex stereotyped motor reflexes including many phenomena formerly termed "subtle seizures"; e) a possible influence on muscle maturation, particularly in relaying cerebellar impulses that modify the histochemical differentiation of myofibres. However, the bulbospinal tracts are probably more influential on muscle development. The corticospinal and corticobulbar tracts subserve different needs in the newborn than at older ages, but are functionally important pathways even at birth.

Cerebral Cortex↗
PubMed1989

[Distribution of RNA during neuronal migration in developing normal and dysplastic brains in man. Acridine orange study].

Acridine orange, a fluorochrome stain of nucleic acids, was used to study neuronal maturation in human brains during development. The central nervous system in 15 normal fetuses and neonates of 16 to 44 weeks gestational age were examined, as well as 24 dysplastic brains exhibiting abnormal cellular migrations. The increase in cytoplasmic RNA of neurons coincides with the onset of neurotransmitter synthesis, temporally synchronized to begin after migration in the cerebral hemispheres but before migration of the external granular layer of the cerebellum. The presence or absence of orange fluorescence in heterotopic nerve cells serves as a marker of the state of maturity by indicating whether the cell was still migrating at the time of death or had already arrived at its definitive site in the brain, whether normal or abnormal. Furthermore, the type of neurotransmitter produced by a given neuron influences ribosomal concentration and hence the intensity of orange RNA fluorescence. Neurons that secrete peptides, acetylcholine, or monoamines show stronger fluorescence than do those synthesizing simple amino acids as transmitters. Transitory transmitters of developing brain may account for stronger fluorescence in certain neurons of the fetus than in the adult, an example being the granule cells of the cerebellar cortex. Acridine orange is a useful supplementary tool in pediatric neuropathology.

Acridine Orange↗
PubMed1989

[Spinal muscular atrophy: disappearance of RNA fluorescence of degenerating motor neurons. An acridine orange study].

The histochemical distribution of nucleic acids has been studied in degenerating motor neurons of 9 children who died with spinal muscular atrophy, using the fluorochrome acridine orange. Ribonucleic acid (RNA) fluorescence disappeared abruptly from involved motor neurons without chromatolysis, attenuation of intensity, or other intermediate transitions that follow axotomy or hypoxic insults. We found a nearly identical pattern in 3 adults with amyotrophic lateral sclerosis. The findings in older subjects are complicated, however, by the presence of cytoplasmic lipofuscin. The autofluorescence of this pigment is inhibited by acridine orange. Our results support the hypothesis that spinal muscular atrophy is a disturbance of the genetically coded mechanism that arrests the programmed physiological death of surplus motor neuroblasts after a certain time in embryonic life, so that the normal lethal developmental process becomes pathological by persisting postnatally. A failure of RNA transcription seems to be primary and results in a failure of synthesis of neurotransmitters, of enzymes, and of cytoplasmic proteins. Consequent inanition leads to cell death.

Acridine Orange↗
PubMed1988

Myopathies associated with hypothyroidism: a review based upon 13 cases.

The clinical and myopathological features of 13 patients with a myopathy occurring in association with hypothyroidism are presented. Seven patients had hypothyroid myopathy, including two with the Hoffmann syndrome and one with the Kocher-Debre-Semelaigne syndrome. Five patients had an inflammatory myopathy and one had polymyalgia rheumatica. Serum CK activity was elevated up to 12-fold in the patients with hypothyroid myopathy and returned to normal after treatment with thyroxine. Pathological changes in these cases included type 1 or type 2 fibre atrophy or hypertrophy, myofibre necrosis and regeneration in four cases and, in one case, prominent core-like areas containing amorphous granulo-filamentous material. The findings in this series of cases illustrate the clinical and histopathological heterogeneity of patients with hypothyroid myopathy and the need to consider other myopathies in hypothyroid patients who present with muscular symptoms.

Adolescent↗
PubMed1987

Hypoxic alterations in neonatal neurons: an acridine orange fluorochromic study of nucleic acids.

Acridine orange, a fluorochromic stain of nucleic acids, was used to study tissue sections of brain and spinal cord in 22 premature and full-term neonates who died within a week after severe fetal distress or birth asphyxia. Neurons suffering hypoxic injury may show either a centrifugal or a centripetal pattern of redistribution of cytoplasmic RNA. Severely involved cells show almost complete loss of orange RNA fluorescence, as well as decreased or condensed DNA fluorescence of nuclear chromatin. The most pronounced changes are observed in motor neurons and in pyramidal cells of the hippocampus. It appears likely that the centrifugal redistribution of ribosomes (chromatolysis) is associated with cell injury, while the centripetal pattern indicates a recovery process or regeneration. Acridine orange provides a convenient supplementary method of assessing the extent of hypoxic encephalopathy in neonates at autopsy. Alterations in RNA distribution may correlate with impairment of neurotransmitter synthesis, but normal maturational differences also must be considered in interpretation.

Acridine Orange↗
PubMed1987

Gliosis and glioma distinguished by acridine orange.

Acridine orange fluorochrome of nucleic acids was applied to sections of cerebral tissue from 20 patients showing acute or chronic reactive gliosis. The results were compared with the findings in 39 well differentiated and malignant astrocytomas. The orange cytoplasmic fluorescence of ribonucleic acid is lacking in reactive astrocytes of all ages including gemistocytes, but is uniformly present in astrocytoma cells. Acridine orange is a useful supplementary stain for distinguishing between astrocytosis and astrocytoma, particularly for small cerebral biopsies showing scattered or diffusely infiltrating pleomorphic glial cells.

Acridine Orange↗
PubMed1987

Juvenile dermatomyositis induced by toxoplasmosis.

A 10-year-old girl from southern Alberta, Canada, who had close contact with cats, developed typical features of dermatomyositis. The diagnosis was confirmed by muscle biopsy. A toxoplasmosis titer was 1:16,384 by indirect fluorescent antibody technique, and the IgM response to toxoplasma was positive. Only minimal improvement followed prednisone and azathioprine administration, but she rapidly improved after 4 weeks of treatment for toxoplasmosis with pyrimethamine and sulfadiazine. A year after the onset of dermatomyositis, she showed no weakness or cutaneous lesions, and a repeat muscle biopsy no longer showed inflammation, perifascicular atrophy, or regeneration of myofibers. She remains asymptomatic more than 2 years after discontinuation of all medications. Investigation for immune deficiency disease 1 year after therapy revealed that lymphocytic response to T-cell and B-cell mitogens was normal, as were immunoglobulin and complement levels. She had mild impairment of natural killer cell activity and a positive antinuclear factor. Her rapid improvement on specific therapy and lack of significant long-term immune deficiency is consistent with acute toxoplasmosis infection in an immunologically competent child.

Antibodies↗
PubMed1986

Cerebral dysgeneses and their influence on fetal muscle development.

Abnormal suprasegmental influences of the brainstem and cerebellum on the developing motor unit during the histochemical stage of muscle development (20-28 weeks gestation) may alter the rate of maturation of striated muscle or may cause abnormal proportions and relative sizes of histochemical fibre types. Such aberrations without primary myopathic or denervative changes are commonly found in children with cerebral malformations, particularly associated with cerebellar hypoplasia. Upper motor neuron disease during embryonic life may explain histochemical alterations in some nonprogressive 'congenital myopathies' such as congenital muscle fibre-type disproportion, nemaline rod disease, and central core disease. Suprasegmental factors also may contribute to some aspects of the muscle pathology in the muscular dystrophies, especially the Fukuyama type of congenital muscular dystrophy regularly associated with cerebral dysgenesis. Fibre-type predominance or delayed histochemical differentiation thus may serve as a useful marker, in the muscle biopsy, of upper motor neuron disease. During the critical period of muscle development implicated, the corticospinal tract probably is of much less importance in muscle maturation than the multiple small bulbospinal pathways which also subserve motor control in nonmammalian vertebrates.

Brain↗
PubMed1986

Cytoplasmic RNA in nervous system tumours in children: a fluorochromic histochemical study using acridine orange.

Acridine orange was used as a fluorochromic histochemical stain of nucleic acids, applied to 78 neoplasms of the central and peripheral nervous systems of 60 children. Some cases were compared with 5 adults and 4 other cases of chronic reactive gemistocytic gliosis. Opposite concentration gradients of cytoplasmic ribonucleic acid (RNA) was demonstrated in tumours of the neuronal/neuroectodermal series, and those of the glial/neuroepithelial series. Minimal AO-RNA fluorescence was seen in 8 cerebellar medulloblastomas and in a retinoblastoma; strong AO-RNA fluorescence occurred in one cerebellar medulloblastoma and in 3 primitive neuroectodemal tumours of the cerebral cortex. Intermediate intensity of fluorescence was found in neuroblastomas, and strong fluorescence was shown in well differentiated ganglioneuroma cells and in cells of chromaffin tumours. Among glial tumours, by contrast, the most anaplastic cells displayed the most RNA fluorescence, while better differentiated astrocytoma cells showed much less. Gradients also were found within some astrocytomas, corresponding to zones of relative anaplasia. Minimal or no fluorescence was detected in reactive gemistocytes or in oligodendroglioma cells. Ependymomas were weakly fluorescent and choroid plexus papillomas showed more fluorescence, similar to the findings in normal ependyma and choroid plexus. Several non-neuroepithelial tumours of the nervous system and Schwannomas also were studied. The acridine orange technique applied to either frozen or paraffin sections of nervous system tumours, has value as an adjunct in the diagnosis and grading of these neoplasms and perhaps in distinguishing reactive gliosis from benign astrocytoma.

Acridine Orange↗
PubMed1986

Hereditary motor sensory neuropathy type I presenting as scapuloperoneal atrophy (Davidenkow syndrome) electrophysiological and pathological studies.

A 14 year old boy with scapuloperoneal muscular atrophy, pes cavus, areflexia and distal sensory loss (Davidenkow syndrome) is described. Nerve conduction velocities were diminished. Sural nerve biopsy demonstrated a reduction in the number of myelinated fibers and early "onion-bulb" formation. These observations support the hypothesis that the scapuloperoneal amyotrophy associated with distal sensory loss may represent a variant of type I hereditary motor sensory neuropathy.

Adolescent↗