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

Ornithine and arginine compounds were highly effective in preventing an increase in blood ammonia and in preventing or minimizing encephalopathy after acute subcoma, coma-inducing, or lethal doses of NH4+. Similar protection was seen after subacute loading with glycine. Ornithine ketoacid derivatives were no more effective than ornithine alone or ornithine glutamate. Ornithine appeared to be a little more effective than arginine, but the differences were slight. Aspartate and glutamate alone were ineffective. Carbamyl glutamate was much less effective than either ornithine glutamate or arginine glutamate. Orotic acid excretion was markedly increased in the presence of excess NH4+. This increment was eliminated with ornithine or arginine, although the reduction with arginine was unpredictably erratic. Aspartate increased the orotic acid excretion and the amount of urea formed. Sodium benzoate was borderline in its effect on the blood ammonia and on orotic acid excretion.
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PMID:Ammonia toxicity: comparative protective effect of various arginine and ornithine derivatives, aspartate, benzoate, and carbamyl glutamate. 350 33

This study compares early and late effects of the injection of hyperosmolar NaCl and urea of equal osmolarity on selected aspects of brain water, electrolyte, carbohydrate, amino acid, urea, and energy metabolism in normal suckling-weanling mice. One hour after treatment, salt-treated mice were critically ill, while the behavior of urea-treated animals could not be distinguished from that of controls. This clinical difference could not be explained on the basis of differences in plasma osmolality, the brain water content, or the degree of hemorrhagic encephalopathy. The injection of NaCl induced a 14-fold increase in plasma insulin and a progressive fall in the plasma glucose concentration (a reduction of 66% at 1 hr). In contrast, plasma glucose levels in urea-injected mice were unchanged. Prior to the fall in plasma glucose levels, metabolite changes in the brains of NaCl-injected mice were compatible with facilitation of transfer of glucose from the blood to the brain, increased metabolic flux in the Embden-Meyerhof and Krebs citric acid cycle pathways, and increased energy production. With the exception of the glucose content (unchanged), similar metabolite changes were seen in brain soon after urea injection. In the brains of the hypoglycemic NaCl-treated mice, glucose levels were reduced 80%, and glycogen 41%. Other metabolite changes were compatible with decreased glycolysis and metabolic flux through the Krebs citric acid cycle. In contrast, with few exceptions, at a similar time after injection, metabolite levels had returned to normal in the urea-treated mice. Permeability of the brain to urea was also examined. Brain urea reached high levels at 2 hr but returned to near baseline at 6 hr. Both hyperosmolar solutions increased the brain content of aspartic and glutamic acids 1 hr after injection. The failure of hypoglycemic mice with hypernatremia and elevated plasma osmolality (range, 416-434 mOsm/kg H2O) to respond to 1 M glucose (30 ml/kg) may have been due to the ill effects of the additional hyperosmolar load. The possibility remains that the encephalopathy induced by hyperosmolar NaCl, but not by hyperosmolar urea, is in some way related to the sudden elevation of brain Na+ and/or Cl- ions.
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PMID:Effects of acute hyperosmolar NaCl or urea on brain H2O, Na+, K+, carbohydrate, and amino acid metabolism in weanling mice: NaCl induces insulin secretion and hypoglycemia. 350 38

Hepatic metabolism is the primary process of elimination of propafenone. It therefore is important to understand the effect of altered liver function on the disposition and elimination kinetics of this drug. Patients with abnormal liver function probably will require treatment with propafenone for cardiac arrhythmias; an understanding of the relationship between liver function and the pharmacokinetics of propafenone will provide a rational basis for optimal dosage adjustments in these individuals. Our results demonstrate that both systemic clearance and bioavailability of propafenone are sensitive to variability in liver function. The bioavailability of propafenone is inversely related to the clearance of indocyanine green (ICG), whereas a direct relationship exists between systemic clearance of propafenone and ICG clearance. Comparisons of clinical parameters with the propafenone data yielded interesting results. An overall clinical grading of severity of liver disease based on the presence or absence of portal hypertension (i.e., varices and/or splenomegaly), prior encephalopathy, and ascites did not correlate well with propafenone results. However, albumin, total bilirubin, serum glutamic oxaloacetic transaminase (SGOT) concentrations and prothrombin time values correlated strongly with the overall results. No definite relationships with subjects' age; weight; and hemoglobin, alkaline phosphatase, lactic acid dehydrogenose, cholesterol, blood urea nitrogen, or creatinine levels were detected. These results demonstrate that moderate to severe liver disease significantly affects the absorption and disposition of propafenone. In patients with cirrhosis, and presumably other forms of hepatic dysfunction, careful adjustments of propafenone doses are needed to optimize therapy.
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PMID:Influence of hepatic dysfunction on the pharmacokinetics of propafenone. 369 82

Deficiency of ornithine transcarbamylase, an enzyme in the urea cycle, results in hyperammonemia. The X-linked recessive inheritance results in neonatal death of affected males but a variable symptomatic pattern in females, with onset of symptoms in childhood. We report the cases of two heterozygous women with onset of severe symptoms (encephalopathy and focal neurologic deficits) in adulthood.
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PMID:Ornithine transcarbamylase deficiency: adult onset of severe symptoms. 382 55

A healthy twenty-month-old boy ingested a maximal dose of valproate from which about 750 mg/kg were absorbed. Cerebral coma, which lasted for twenty hrs, was followed by an undisturbed period of approximately sixteen hrs. Death from cardiorespiratory failure due to severe bronchopneumonia occurred 46.5 hrs after the ingestion of the drug. The serum valproic acid concentration reached a peak of 1061 micrograms/ml within three hours, and fifteen minutes before death it had fallen to 187 micrograms/ml. The half-life of 16.6 hrs was within the range usually found. Metabolic acidosis, hypernatraemia and hyperosmolarity could be corrected, unlike the hypocalcaemia, which developed later. Bilirubin, GOT, GPT, gamma-GT, alkaline phosphatase, blood glucose, diastase, urea, creatinine, haemoglobin as well as PT and PTT and the platelet count were all normal. Leucopenia with 1,600 per microliter developed only during the bronchopneumonial stage. The histo-pathological findings were acute hypoxic damage of the myocardium, kidneys and certain neurones of vulnerable areas of the brain (neuronal microvesiculation and tigrolysis) in addition to a severe cerebral oedema in the final stage. A morphological substrate of an acute valproate encephalopathy was not demonstrable. The liver showed no necrosis or cholostasis. The vertebral marrow was inconspicuous. All the results indicate that liver function was not impaired in spite of the initial maximal concentration of valproic acid. In all probability the patient might have survived the acute valproate intoxication had it not been for the bronchopneumonia.
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PMID:Acute valproate intoxication with fatal outcome in an infant. 393 45

Portasystemic encephalopathy has been a major deterent to the utilization of total or non-selective shunts. A procedure to determine the maximum rate of urea synthesis (MRUS) has been developed and a depression in the ability to synthesize urea has been shown to correlate closely with the development of encephalopathy. Utilizing this procedure and a modified ammonium tolerance curve, a controlled comparison was instituted between selective and non-selective shunts. Following a non-selective or total shunt, there was a definite deterioration in both the MRUS and the ammonium chloride tolerance curve which was accompanied by a high rate of clinical encephalopathy. In marked contrast, the selective shunt, which maintains portal venous perfusion of the liver, showed little or no change in the MRUS and the ammonium chloride tolerance curve following the selective shunt and there was a very low incidence of encephalopathy. The difference between the non-selective and selective shunt in maintenance of urea synthesis, metabolism of ammonium chloride, and the development of clinical encephalopathy show the selective shunt procedure to be definitively superior in this regard.
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PMID:The metabolic basis of portasystemic encephalopathy and the effect of selective vs nonselective shunts. 441 59

When normal individuals eat 0.33 g protein N/kg body weight (BW)((3/4)) per day, they excrete 10-15 mg urea N/h per kg BW((3/4)). If they now ingest (at 0 h) 0.27 (dose A), 0.40 (dose B), 0.53 (dose C), 0.94 (dose D), or 1.33 (dose E) g protein N/kg BW((3/4)) (in the form of casein, ovalbumin, or lactalbumin), the rate of urea N excretion accelerates within 4 h. At dose C a maximal rate of urinary urea N excretion (MRUE) is reached, which averages 55 mg urea N/h per kg BW((3/4)) and which persists for 16 h. Higher doses of protein do not further accelerate urea excretion, but prolong the duration of MRUE to 28 h (after dose E). Blood urea N (BUN) rises by 7-20 mg/100 ml during the first 8 h after dose C to E, and remains stable within +/-5 mg/100 ml during the ensuing 8-28 h of MRUE. Each increment of protein above dose C causes a further increment in plasma alpha-amino N. During infusion of free amino acids at a rate of 110 or 165 mg amino acid N/h per kg BW((3/4)) for 12 h, rate of urea excretion increases to the MRUE value produced by dose C-E of oral protein.These findings indicate that MRUE corresponds to a period of maximal rate of urea synthesis (MRUS). MRUS is greater than MRUE because one fraction of newly formed urea is hydrolyzed in the gastrointestinal tract, and another fraction may accumulate temporarily in body water during the MRUE period. Oral neomycin reduces the proportion of urea hydrolyzed in the gut to less than 20%; its extent is measured by recovery in the urine of a tracer dose of [(14)C]urea injected intramuscularly during determination of MRUE. Accumulation of urea in body water is estimated from increment in BUN during the period of MRUE measurement (8-24 h after dose E of casein) and from body water measured with (3)H(2)O. Then MRUS is calculated as: ([mg urea N excreted between 8 and 24 h after dose E] + [BUN at 24 h - BUN at 8 h] x [body water]) x (100/% recovery [(14)C]urea) x (1/kg BW((3/4))) x (1/16 h).MRUS in 10 normal subjects averaged 65 mg urea N/h per kg BW((3/4)) (range 55-76), and in 34 cirrhotics 27 mg urea N/h per kg BW((3/4)) (range 6-64). Among 19 cirrhotic patients fed 40, 60, 80, or 100 g protein daily for successive 10 day periods, the occurrences of hyperammonemia, hyperaminoacidemia, and encephalopathy at each level of protein intake were inversely related to MRUS value.
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PMID:Maximal rates of excretion and synthesis of urea in normal and cirrhotic subjects. 472 56

22 cirrhotic patients with chronic encephalopathy were given oral zinc supplementation or placebo in a double-blind randomised trial. In the group which received zinc acetate 600 mg a day for 7 days, serum zinc had been restored to normal by day 8. On day 8 hepatic encephalopathy, as assessed by a trailmaking test, was improved in the supplemented group but not in the placebo group. There was also a significant increase in blood urea nitrogen in the supplemented group. Short-term oral zinc supplementation probably improved hepatic encephalopathy by correcting the zinc deficiency that compromises conversion of ammonia to urea. The duration of this improvement requires further investigation.
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PMID:Oral zinc supplementation improves hepatic encephalopathy. Results of a randomised controlled trial. 614 51

Oral ingestion of a new rat poison that antagonizes nicotinamide metabolism, N-3-pyridylmethyl-N'-p-nitrophenyl urea (PNU, Vacor), is known to cause diabetes mellitus. I describe neurologic complications of PNU ingestion in 12 patients 19 to 50 years of age who swallowed between 0.39 and 7.02 g of PNU. One died within a day, and five died of chronic complications 40 to 182 days after taking the poison. Apart from the acute hyperglycemic ketoacidosis, the clinical presentation was variable, but orthostatic hypotension, gastrointestinal hypomotility, peripheral neuropathy, and encephalopathy were typical. The peripheral, autonomic, and central-nervous dysfunction could develop either acutely or other several days. It is possible that nicotinamide, given parenterally within minutes, prevents toxicity, but the cases discussed in this paper indicate that the neurologic deficits may progress despite later nicotinamide administration. Neurologic improvement took many months. Full recovery was uncommon, and the orthostatic, hypotension tended to persist.
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PMID:The neurotoxicity of the rat poison vacor. A clinical study of 12 cases. 624 67

Toxic irreversible encephalopathic syndromes developed in 2 patients treated with lithium carbonate and haloperidol. Symptoms consisted of lethargy, fever, tremulousness, confusion, and extrapyramidal and cerebellar dysfunction, accompanied by leucocytosis and elevated serum enzyme, blood urea nitrogen, creatinine and fasting blood glucose levels. One patient suffered widespread irreversible brain damage; the other was left with persistent dyskinesias. Although causal factors have not been identified, this report and others in the literature suggest that diffuse irreversible encephalopathy may occasionally develop in individuals with abnormal brain sensitivity to the lithium carbonate/haloperidol combination. Evidence for this is based on the fact that in our patients and others mentioned in the literature the dosage and blood levels of lithium were not high.
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PMID:Toxic irreversible encephalopathy induced by lithium carbonate and haloperidol. A report of 2 cases. 641 23


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