Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0085584 (encephalopathy)
 18,178 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The binding characteristics of gamma-aminobutyric acid-A (GABA-A) receptors and the kinetic characteristics of the target enzyme of GABA synthesis in nerve terminals, glutamic acid decarboxylase (GAD), were studied in a dog model of portal-systemic encephalopathy obtained by porta-caval shunt performed in dimethylnitrosamine pretreated animals. Furthermore the properties of dopamine receptors and the levels of catecholamines of encephalopathic dogs were investigated. The mild stage of encephalopathy was characterized by an up-regulation of the inhibitory GABA-A receptors probably related to a decrese of GABA in nerve terminals since GAD was decreased and by a slight decrease of catecholamines and by an increased synthesis of octopamine associated with a decreased affinity of dopamine receptors. In the severe stage there was a selection of high affinity GABA-A receptors with an increased number of benzodiazepine recognition sites which were supersensitive to GABA stimulation, a decreased number of Dopamine D-2 receptors and a marked reduction of catecholamines. These data seem to suggest that the neurological disturbances of experimental portal-systemic encephalopathy might be the result of an imbalance between inhibitory and excitatory systems leading to a prevalence of the first one.
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PMID:Alterations of GABA-A and dopamine D-2 brain receptors in dogs with portal-systemic encephalopathy. 184 16

The examination of cerebrospinal fluid has provided useful information for diagnosis of CNS infections. The progress of analytical technology has brought the possibility to detect very small amounts of chemical substances. I thought that new information from brain should be obtained by using modern analytical technology for several substances in CSF. Free amino acid pattern, glutamine, homocarnosine, glutamic acid decarboxylase (GAD), neuron specific enolase (NSE) and 2',5'-oligoadenylic acid synthetase (2-5 A) in CSF have been examined for information of brain injury and dysfunctions. The results are as follows. 1) The individual difference and constancy of free amino acid pattern in CSF were found in children without any neurological diseases. 2) The levels of free amino acids in CSF increased in the acute phase of bacterial meningitis. 3) High levels of glutamine in CSF of children with acute bacterial meningitis were normalized during the recovery phase. 4) A marked imbalance of free amino acids in CSF was found in children with Lennox-Gastaut syndrome. 5) A decrease of homocarnosine levels in CSF was related with the degree of unconsciousness in children suffering from neurological diseases. 6) High GAD activities in CSF were observed in the acute phase of aseptic meningitis and after intrathecal injection of methotrexate for the therapy against meningeal leukemia. 7) High NSE activities in CSF were found in the acute phase of bacterial meningitis, intracranial hemorrhage, encephalopathy and encephalitis. 8) High 2-5A activities CSF were measured in the acute phase of mumps meningitis with subsequent decreases during the recovery phase. These results suggest that several substances in CSF are useful as markers of brain injury and dysfunction.
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PMID:[Cerebrospinal fluid as informative source of the brain]. 201 95

Taurine is an important age- and compartment-specific part of the pool of free amino acids in all human tissues and fluids examined. Besides an active taurine transport system, the mechanisms to assure compartment-specific taurine-homeostasis in humans is presumably due to a compartment-specific taurine synthesis. By the identity of cysteine-sulfinic acid - and glutamate-oxalate transaminase as well as of cysteine-sulfinic acid - and glutamic acid decarboxylase taurine biosynthesis via cysteine-sulfinic acid shows direct metabolic relationship between biochemical pathway of cysteine-sulfinic acid and taurine on one side, and of the dicarbonic acid and their biological decarboxylates on the other side. In the parenteral and enteral nutrition of premature babies as well as of adults with portosystemic encephalopathy or with extreme thiamine deficiency, there is - besides an inconstant parallel of exogenous taurine supply and plasma taurine homeostasis - a constant parallel between definitely lowered plasma taurine concentrations and comparably distinct disturbance of the homeostasis of the dicarbonic acids and/or their biosynthetic products. A metabolic connection seems likely. The hypothesis of Sturman et al. in 1976 that taurine is an essential part of the human nutrition at least in the premature or full-term newborn phase of life could not be supported in the subsequent studies of different groups of authors - neither in relation to the nitrogen balance, childhood-development, hepatic cellular function, biliary-acid metabolism, intestinal fat absorption nor any organ-specific function. The nutritional value of taurine in humans still remains unclear in regard to specific physiologic as well as specific pathophysiologic phase of metabolism.
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PMID:[Taurine--recent views and importance for artificial feeding]. 313 85

We attempted to produce a rat model of brain aluminum toxicity in order to explore whether or not aluminum accumulation produces the neurochemical changes observed in brains of patients who die with dialysis encephalopathy. Daily subcutaneous injection of Al(OH)3 caused marked elevation of serum aluminum concentrations, but did not increase brain aluminum contents, either in rats with normal renal function, or in rats with unilateral or 5/6 nephrectomies. LiCl pretreatment, which has been reported to cause irreversible renal failure, did not impair renal function nor aid in achieving elevated brain aluminum contents. No reductions in brain contents of gamma-aminobutyric acid (GABA) or in glutamic acid decarboxylase (GAD, E.C.4.1.1.15) and choline acetyltransferase (ChAT, E.C.2.3.1.6) activities were observed in aluminum-treated rats. We conclude that the rat is not a suitable laboratory animal to explore the role of aluminum toxicity in causing the GABA and ChAT deficits present in brains of hemodialyzed human patients.
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PMID:Inability to produce a model of dialysis encephalopathy in the rat by aluminum administration. 360 Sep 63

The GABA level, and the glutamic acid decarboxylase (GAD) and GABA-aminotransferase (GABA-T) activities were measured in the cortex and striatum of rats in which the early stages of hepatogenic encephalopathy (HE) had been induced by few intraperitoneal administrations of thioacetamide (TAA). Besides, the GABA binding to synaptic plasma membranes (SPM) isolated from whole brain hemispheres was examined. The first part of the study revealed significant changes both in the neurotransmitter level and in the enzyme activities; no correlation was observed, however, between the accumulation of GABA and the progression of the disease. In contrast, subsequent stages of HE in the TAA model were found to be characterized by a gradual decrease of both Bmax and KD values for GABA binding, which may reflect a gradual decrease in the number of binding sites, accompanied by sensitization of the remaining receptors. The results are discussed in view of the possible involvement of this inhibitory neurotransmitter in the pathogenesis of HE.
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PMID:Changes in the metabolism and binding of GABA in the rat brain in thioacetamide-induced hepatogenic encephalopathy. 370 58

A former study indicated that hypoxic-ischemic encephalopathy in rat sustained during early postnatal life may result in permanent epileptic activity in the baseline electroencephalogram. We, therefore, investigated whether the presumed higher firing frequency and metabolic activity of neurons in such hypoxia-damaged cortical areas would be reflected by an enhanced light microscopic immunoreactivity of gamma-aminobutyric acid (GABA), the two isoforms of glutamic acid decarboxylase (GAD67 and GAD65), the mitochondrial enzymes cytochrome c oxidase and ATP synthase, and/or glial fibrillary acidic, protein (GFAP). To that end rat pups, 12-13 days of age, were unilaterally exposed to hypoxic-ischemic conditions and, after a survival period of 2 and 6 1/2 months, respectively, killed by perfusion fixation. After dissection of the brain, coronal vibratome sections of animals showing cortical damage were immunostained for the presence of the above-mentioned antigens. Subsequent qualitative analysis revealed that the surroundings of cortical infarctions were unambiguously characterized by a disordered neural network containing numerous nerve cells, fibers and/or endings showing an enhanced immunoreactivity for GABA, both isoforms of glutamic acid decarboxylase, and cytochrome c oxidase and ATP synthase, while the astrocytes showed an enhanced immunoreactivity for GFAP. The diverse patterns of enhanced immunoreactivity suggested, furthermore, a wider low-to-high range of metabolic activities in both excitatory and inhibitory neurons.
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PMID:Permanent increase of immunocytochemical reactivity for gamma-aminobutyric acid (GABA), glutamic acid decarboxylase, mitochondrial enzymes, and glial fibrillary acidic protein in rat cerebral cortex damaged by early postnatal hypoxia-ischemia. 752 89

The aim of the present study was 2-fold: (1) to determine the ratio between the amount of GAD67 and GAD65 (two isoforms of the GABA synthetizing enzyme glutamic acid decarboxylase) in nerve endings in the mature rat cerebral cortex damaged by hypoxia-ischemia during early postnatal life; and (2) to compare two different computer-assisted procedures developed for quantitative analysis of immunofluorescence images obtained with a confocal laser scanning microscope (CLSM). One procedure was based on a program present in the standard Leica CLSM software packet for full-field analysis, the other on a specially written program for object-oriented analysis run on a Kontron IBAS-KAT image analysis system. To this end, rat pups were unilaterally exposed to hypoxic-ischemic conditions and, after a survival period of 6.5 months, sacrificed by perfusion fixation. After dissection of the brain and vibratome sectioning, three animals with substantial damage on one cortical side were selected. Sections of these animals were double-stained with primary antibodies against GAD67 and GAD65 and fluorophore-conjugated secondary antibodies and subsequently sampled with a CLSM. Analysis of the CLSM images with both computer-assisted procedures showed for all three animals a clear tendency to higher GAD67/GAD65 ratios in cortical GABAergic nerve endings on the hypoxia-damaged side than in matched areas on the contralateral side. This outcome led to the following conclusions. (1) The correspondence between the outcome of both analysis procedures indicates that both procedures are valid for quantification of immunofluorescence images of nerve endings obtained with a CLSM. (2) The outcome lends further support to our view that hypoxic-ischemic encephalopathy, sustained during early postnatal life, may result in an unstable cortical network generating abnormal synchronizations and oscillations which can be amplified and propagated as true epileptic discharges. In such a network both excitatory and inhibitory processes are tonically enhanced, the latter probably as a homeostatic reaction tending to keep abnormal excitation within physiological limits.
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PMID:Quantitative immunofluorescence data suggest a permanently enhanced GAD67/GAD65 ratio in nerve endings in rat cerebral cortex damaged by early postnatal hypoxia-ischemia: a comparison between two computer-assisted procedures for quantification of confocal laser scanning microscopic immunofluorescence images. 782 Jun 25

We analysed a series of 24 adult patients with idiopathic (10 cases) and paraneoplastic (14 cases) opsoclonus-myoclonus syndrome (OMS) to ascertain possible differences in clinical course and response to immunotherapies between both groups. Associated tumours were small-cell lung cancer (SCLC) (nine patients), non-SCLC (one patient), breast carcinoma (two patients), gastric adenocarcinoma (one patient) and kidney carcinoma (one patient). Patients with paraneoplastic OMS were older [median age: 66 years versus 40 years (P = 0.006) of those with idiopathic OMS] and had a higher frequency of encephalopathy (64% versus 10%; P = 0.02). Serum from 10/10 idiopathic and 12/14 paraneoplastic OMS patients showed no specific immunoreactivity on rat or human brainstem or cerebellum, lacked specific antineuronal antibodies (Hu, Yo, Ri, Tr, glutamic acid decarboxylase, amphiphysin or CV2) and did not contain antibodies to voltage-gated calcium channels. The two paraneoplastic exceptions were a patient with SCLC, whose serum contained both anti-Hu and anti-amphiphysin antibodies and a patient with breast cancer who had serum anti-Ri antibodies. The clinical course of idiopathic OMS was monophasic except in two elderly women who had relapses of the opsoclonus and mild residual ataxia. Most idiopathic OMS patients made a good recovery, but residual gait ataxia tended to persist in older patients. Immunotherapy (mainly intravenous immunoglobulins or corticosteroids) seemed to accelerate recovery. Paraneoplastic OMS had a more severe clinical course, despite treatment with intravenous immunoglobulins or corticosteroids, and was the cause of death in five patients whose tumours were not treated. By contrast the eight patients whose tumours were treated showed a complete or partial neurological recovery. We conclude that idiopathic OMS occurs in younger patients, the clinical evolution is more benign and the effect of immunotherapy appears more effective than in paraneoplastic OMS. In patients aged 50 years and older with OMS who develop encephalopathy, early diagnosis and treatment of a probable underlying tumour, usually SCLC, is indicated to increase the chances of neurological recovery. At present, there are no immunological markers to identify the adult patients with paraneoplastic OMS.
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PMID:Clinical outcome in adult onset idiopathic or paraneoplastic opsoclonus-myoclonus. 1115 70

Pyridoxine-dependent seizures have been recognised for 40 years, but the clinical and biochemical features are still not understood. It is a rare recessively inherited condition where classically a baby starts convulsing in utero and continues to do so after birth, until given pyridoxine. Many of these early onset cases also have an acute encephalopathy and other clinical features. Late onset cases are now recognised with a less severe form of the condition. Seizures can break through with intercurrent illness but otherwise remain controlled on pharmacologic doses of pyridoxine. The long-term outcome is affected by several factors including whether onset is early or late and how soon pyridoxine is given. Biochemical studies have been sparse, on very small numbers. There does not appear to be any defect in the uptake or metabolism of pyridoxine or pyridoxal phosphate (PLP). For a long time glutamic acid decarboxylase (GAD), a pyridoxal-dependent enzyme, has been suspected to be the abnormal gene product, but glutamate and gamma-aminobutyric acid (GABA) studies on the cerebrospinal fluid (CSF) have been contradictory and recent genetic studies have not found any linkage to the two brain isoforms. A recent report describes raised pipecolic acid levels in patients but how this ties in is unexplained.
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PMID:Pyridoxine-dependent seizures: a clinical and biochemical conundrum. 1268 5

The pediatric neurotransmitter disorders represent an enlarging group of neurological syndromes characterized by abnormalities of neurotransmitter synthesis and breakdown. The disorders of dopamine and serotonin synthesis are aromatic amino acid decarboxylase deficiency, tyrosine hydroxylase deficiency, and disorders of tetrahydrobiopterin synthesis. Amino acid decarboxylase, tyrosine hydroxylase, sepiapterin reductase, and guanosine triphosphate cyclohydrolase (Segawa disease) deficiencies do not feature elevated serum phenylalanine and require cerebrospinal fluid analysis for diagnosis. Segawa disease is characterized by dramatic and lifelong responsiveness to levodopa. Glycine encephalopathy is typically manifested by refractory neonatal seizures secondary to a defect of the glycine degradative pathway. gamma-amino butyric acid (GABA) metabolism is associated with several disorders, including glutamic acid decarboxylase deficiency with nonsyndromic cleft lip/ palate, GABA-transaminase deficiency, and succinic semialdehyde dehydrogenase deficiency. The latter is characterized by elevated gamma-hydroxybutyric acid and includes a wide range of neuropsychiatric symptoms as well as epilepsy. Pyridoxine-dependent seizures have now been associated with deficiency of alpha-aminoadipic semialdehyde dehydrogenase, as well as a new variant requiring therapy with pyridoxal-5-phosphate, the biologically active form of pyridoxine.
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PMID:The pediatric neurotransmitter disorders. 1769 69


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