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Query: UMLS:C0085584 (encephalopathy)
 18,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An ultrastructural study of cerebral cortex was performed in rats during the preictal period following the administration of the convulsant methionine sulfoximine (MSO). The morphologic changes were restricted to astrocytes and consisted of cytoplasmic enlargement, mitochondrial and rough endoplasmic reticulum proliferation, accumulation of glycogen, development of cisternal and saccular smooth endoplasmic reticulum, nuclear chromatin clumping, and hydropic degenerative changes. These findings resemble those seen in experimental ammonia encephalopathy, suggesting an important role of ammonia in the evolution of these morphologic changes. The findings, moreover, suggest that the primary effect of MSO is on astrocytes and that abnormalities in astrocytes may play a role in the development of MSO-induced seizures.
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PMID:Ultrastructural study of methionine sulfoximine-induced Alzheimer type II astrocytosis. 55 86

A sequential light and electron microscopic study of cerebral cortex was performed in a rat model of portal-systemic encephalopathy produced by creating a portacaval shunt and followed by ammoniate resin feedings. Prior to coma, astrocytes were characterized ultrastructurally by marked cytoplasmic enlargement, proliferation of mitochondria and endoplasmic reticulum, and an accumulation of cytoplasmic glycogen. The Alzheimer type II astrocyte change was seen only in coma and was characterized ultrastructurally by additional hydropic and degenerative mitochondrial and nuclear changes. Attempts at reversal of the encephalopathy were successful only if ammoniated resin feedings were discontinued prior to coma. Results suggest (1) that the astrocyte response initially reflects an ammonia-induced increased metabolic activity in that cell; (2) that subsequently a gliopathy develops having the light microscopic appearance of the Alzheimer type II change; and (3) that the Alzheimer type II astrocyte change may be responsible for an irreversible clinical course in this experimental condition.
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PMID:A light and electron microscopic study of experimental portal-systemic (ammonia) encephalopathy. Progression and reversal of the disorder. 55 21

Cerebral biopsies were obtained for electron microscopy 48 and 72 hours after the onset of encephalopathy from a child with severe Reye's syndrome. Gravely ill at the time of craniectomy to relieve cerebral hypertension, the child survived and recovered good brain function; therefore, the biopsy findings appear to reflect the organelle pathology of the brain at a severe yet reversible stage in the disease process. The cardinal ultrastructural changes in the brain in Reye's syndrome are astrocyte swelling and partial deglycogenation, myelin bleb formation and universal injury of neuron mitochondria. The mitochondrial injury consists of matrix disruption with moderate but not massive swelling. Dilatation of rough endoplasmic reticulum and nuclear changes occurred only in neurons with severely altered mitochondria. The organelle pathology of the brain in this case did not resemble the organelle pathology of the brain in human "hepatic encephalopathy" or in experimental ammonia intoxication in primates. The mitochondrial ultrastructure of the cerebral neurons resembled the unique mitochondrial ultrastructural changes seen in the liver parenchyma in Reye's syndrome.
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PMID:Brain ultrastructure in Reye's syndrome. 117 96

Two cell lines, CNS-5 and CNS-6, were established by cocultivation of sedimented cells in cerebrospinal fluid (CSF) from two anti-human T-lymphotropic virus type I (HTLV-I) antibody-positive male patients with encephalopathy and HTLV-I-associated myelopathy, respectively, with peripheral blood mononuclear cells from a healthy seronegative female. These cell lines, possessing a normal female karyotype, revealed similar characteristics as follows; they expressed HTLV-I-related antigens, they produced C-type retrovirus particles, HTLV-I provirus genomes were integrated into their DNAs, and they had CD4+ activated T-cell markers. In addition, immunocytochemical and immunoelectron microscopic studies showed peculiar immunoreactivity of these cell lines with anti-alpha/beta T-cell antigen receptor (TCR) antibodies; beta Fl, defining beta chain epitope, was only positive in the perinuclear spaces and rough endoplasmic reticulum in some cells, and WT31, recognizing alpha/beta framework, was mostly negative, while CD3 was expressed in the majority of the cells. These facts indicate that HTLV-I-infected cells were present in CSF of these two patients, and suggest that neurological disorders associated with HTLV-I may not be restricted to myelopathy and may include brain abnormalities.
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PMID:Characterization of two human lymphoid cell lines producing human T-lymphotropic virus type I (HTLV-I) isolated from patients with HTLV-I-associated myelopathy or encephalopathy. 167 60

The aetiology and pathogenesis of Reye's syndrome (RS) are incompletely understood. A number of environmental toxins and biological agents, including viruses, have been postulated to cause RS, either acting alone or synergistically. Most investigations have suggested that the primary insult is in the liver mitochondria, leading to a complex biochemical catastrophe, with death from encephalopathy. Margosa oil (MO), a long-chain fatty acid compound, has been shown to cause a Reye-like syndrome with death from hepatoencephalopathy, in children in Malaysia and India. The present time-course study performed in MO-administered mice showed the development of hepatic lesions with many features of RS. MO acts rapidly, within 30 min, on the nuclei of hepatocytes inducing mitoses and binucleated cells. This is followed by mitochondrial injury, with swelling, rarefaction of matrix, loss of dense bodies, pleomorphism, and loss of ribosomes starting at 60 min. There is loss of liver glycogen, and proliferation and hypertrophy of the endoplasmic reticulum (ER), followed by the presence of lipid droplets in the hyaloplasm, and globules within dilated cisterns of the ER. Additional fatty acids from lipolysis of body adipocytes, and fat globules from intestinal MO ingestion further aggravate the liver fatty change. There is evidence of fat globule ingestion by endocytosis into hepatocytes at the level of the sinusoids. The development of microvesicular liver steatosis and glycogen depletion due to involvement of liver cell organelles occur rapidly as in RS.
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PMID:Animal model of margosa oil ingestion with Reye-like syndrome. Pathogenesis of microvesicular fatty liver. 259 49

We examined the oxidation of different chain length fatty acids in the leukocytes and the quantity of lipid peroxides in the plasma of two Reye syndrome patients. We have found that the oxidation of [1-14C] octanoic acid in homogenates of leukocytes from one of the Reye syndrome patients was only 38 percent of the control, whereas oxidation of [1-14C] palmitic and [1-14C] lignoceric acid was slightly increased. The level of lipid peroxides in the serum of both of the Reye Syndrome patients was 4.42 and 3.04 times higher than the control level. These results suggest that impaired oxidation of medium chain fatty acids (octanoic acid) and higher levels of lipid peroxides may contribute to the pathogenesis of cellular toxicity in Reye Syndrome. Reye Syndrome (RS) was first described by Reye et. al. in 1963 and is now recognized as an important cause of morbidity and mortality in infants and children. The clinical course in RS consists of an antecedent viral illness with subsequent encephalopathy and hepatic dysfunction. Laboratory findings in RS include hypoglycemia, hyperammonemia, free fatty acidemia, elevated organic acids and amino aciduria. The ultrastructural findings in RS patients include changes in mitochondria, smooth endoplasmic reticulum morphology, and an increase in the number of peroxisomes. The elevation of serum free fatty acids in RS and their decrease in patients who improve clinically suggests a disturbance in fatty acid metabolism. To understand the role of free fatty acids in the pathogenesis of RS, we examined the levels of lipid peroxides in plasma and catabolism of fatty acids of different chain lengths in leukocytes from RS patients.
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PMID:Reye syndrome: rate of oxidation of fatty acids in leukocytes and serum levels of lipid peroxides. 276 52

To determine the morphological substrate of acute methotrexate (MTX) encephalopathy, light and electron microscopic studies were performed on rat brains after short-term intraperitoneal (IP) and intraventricular (IV) injections of MTX. In both models, Alzheimer type II astrocytosis was the initial and major pathologic alteration seen by light microscopy. The neurons, oligodendrocytes, myelin and endothelial cells were relatively spared. Ultrastructural studies showed pleomorphism and condensation of mitochondria, membrane-bound vacuoles, prominent stacks of sparsely granular, rough endoplasmic reticulum and progressive hydropic swelling of astrocytic perikarya and their processes. The astroglial alterations were reversible after cessation of the drug but persisted for a longer time with repeated IP administration. Gastrointestinal complications and overall mortality were also greater with higher doses and increasing frequency of IP MTX injection. White matter necrosis was noted only after IV injection of high-dose MTX. The neuropathologic changes of MTX leukoencephalopathy can be replicated in an animal model by IV injection of the drug. The reversibility of the changes that were seen following IP administration correlates with the transient neurologic deficits observed in some patients after high-dose systemic MTX therapy. The initially selective astroglial effect suggests that astrocytes might be a target for MTX toxicity, although other central nervous system components may also be adversely affected by the drug.
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PMID:Morphologic alterations in rat brain following systemic and intraventricular methotrexate injection: light and electron microscopic studies. 290 97

An animal model of central distal axonopathy following chronic administration of phenytoin is described. Male C57/BL6J mice received diphenylhydantoin (DPH) in the daily diet (liquid diet 'Stardit', supplemented with vitamins) over a period of 8 weeks. Control and experimental animals were pair-fed. Twelve mice of both groups were perfused via the left ventricle with glutaraldehyde. Representative samples of the cerebral cortex (area 3), cerebellum (vermis and deep cerebellar nuclei), thalamus, hypothalamus, and liver were embedded in araldite. Semi-thin sections and electron microscopy of the cerebellar vermis revealed marked dystrophic changes in the Purkinje cell axons. The presynaptic segments of Purkinje cell axons in the deep cerebellar nuclei showed massive enlargement and swelling due to accumulation of spherical particles and tubular structures in the axoplasm. These structures represent a proliferation of the smooth endoplasmic reticulum. Identical changes were found in hepatocytes of treated animals. Because phenytoin induces hepatic microsomal enzymes, we suggest that phenytoin-related Purkinje cell damage may be produced by an induction of Purkinje cell microsomes with proliferation of the smooth endoplasmic reticulum which causes a swelling and enlargement of presynaptic segments of Purkinje cell axons in deep cerebellar nuclei. Chronic phenytoin administration to mice is a new model of phenytoin-induced encephalopathy and of distal axonopathy of cerebellar neurons.
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PMID:Damage of Purkinje cell axons following chronic phenytoin administration: an animal model of distal axonopathy. 402 72

The ultrastructural changes in cerebellar encephalopathy induced by intravenous injection of poly I:C in young chickens were studied. The neuroglia and the small blood vessels showed the most severe injury. In the astroglia, initial alterations consisted of a mild cytoplasmic swelling whereas terminally, evagination of the outer nuclear membrane, formation of large vacuoles, and mitochondrial swelling occurred. In the cortex, oligodendroglial alterations consisted of dilatation of the nuclear membranes and of the endoplasmic reticulum, whereas in the white matter, the interfascicular oligodendroglia exhibited clumping and coagulation of the chromatin material. Some small blood vessels appeared normal, while others showed massive erosion of the endothelium resulting in aneurysm-like ballooning of the vascular wall. The granule cells displayed marked edema. The myelin of nerve fibers showed an accumulation of fluid initially, with splitting occurring in the terminal stages. These studies indicated a severe cytotoxic effect of poly I:C on the cerebella of young chickens.
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PMID:Ultrastructural changes in chick cerebellum induced by polyinosinic polycytidylic acid. 514 69

Sixteen male Wistar rats, 1 year after injection of streptozotocin or vehicle, were fixed by whole-body perfusion, the brains were removed and processed for light and electron microscopy. Study of semithin sections from the hypothalamic area revealed changes in the arcuate nucleus and median eminence. The lesions, in comparison with controls, were subjected to a blind semiquantitative evaluation. The following changes were observed by light microscopy in diabetic rats: accumulation of glycogen (P < 0.01), degeneration of neurons (P < 0.05), hypotrophy of tanycytes (P < 0.01), and axonal changes. Electron microscopy of diabetic rats revealed that glycogen was increased in neuronal bodies and processes (axons, synapses), also in tanycytes, and glia cells. In neurons were seen: dilated and fragmented endoplasmic reticulum, degranulated ergastoplasm, loss of organelles, increased number of microtubuli, myelin figures, irregularities in the form of nuclei, and appearance of chromatin. The tanycytes in diabetic animals were reduced in volume, had an increased nuclear cytoplasmic ratio, a reduced number of organelles, short basal processes, and almost complete loss of the apical processes. These changes demonstrate the existence, under experimental conditions, of an encephalopathy pathogenetically related to streptozotocin-induced diabetes.
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PMID:Hypothalamic lesions in rats with long-term streptozotocin-induced diabetes mellitus. A semiquantitative light- and electron-microscopic study. 743 62


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