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

Repeated administration of thioacetamide (TAA) to CD1 mice produced hepatic failure and biochemical and behavioral effects characteristic of hepatogenic encephalopathy (HE). The symptoms in mice resembled those previously observed in rats after similar treatments. It is, however, obvious that both in rats and mice the severity of symptoms depends not only on dose and dosing schedule of TAA, but also on strain and body weight (age). Administration of 5-fluoromethylornithine (5FMOrn), a selective inactivator of ornithine aminotransferase (OAT), significantly reduced mortality, and it ameliorated most of the TAA-induced pathologic symptoms, such as hypothermia, decreased locomotor and exploratory behavior, pathologic liver function and amino acid patterns. The most prominent biochemical consequence of 5FMOrn administration is the elevation of ornithine concentrations in tissues, including the brain, and in body fluids. Elevated ornithine concentrations are, therefore, the most likely basis for the therapeutic effects of 5FMOrn. In agreement with this notion is the enhancement of citrulline and urea formation. These findings and the observation that administration of ornithine in combination with a branched-chain 2-oxoacid ameliorated the pathologic symptoms of portal-systemic encephalopathy suggest inhibition of OAT in the treatment of this disease. The liver protective effect of 5FMOrn is not yet understood; the enhancement of regenerative processes is a likely explanation.
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PMID:Effects of inhibition of ornithine aminotransferase on thioacetamide-induced hepatogenic encephalopathy. 847 73

By the end of a dialysis session the patient had a generalized convulsive seizure. Then meningeal syndrome, right-sided hemiparesis with central lesion of right facial nerve and bilaterally positive extensor plantar response were found. Because of the increase of blood pressure and then increased body temperature the diagnosis of acute hyponatraemic encephalopathy was not made only on the basis of the plasma ionogram (Na+ 110mEq/1) but also after excluding possible subarachnoid haemorrhage and acute cerebrospinal meningitis and encephalitis by cerebrospinal fluid examination. Hyponatraemia found in some patients suffering from chronic renal insufficiency is increased by haemodialysis session. Cerebral oedema which is proportional to natraemia is caused by urea disolation from intracellular to extracellular fluid. This process increases concentration gradient between intracellular and extracellular fluids. The perceptible neurological signs occur as natraemia declines below 120 mEq/l.
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PMID:[Acute hyponatraemic encephalopathy in a patient on chronic hemodialysis program -- a case report]. 850 50

Zinc deficiency is common in cirrhosis and has been involved in the altered nitrogen metabolism. In this study, we measured the effects of zinc supplementation on the dynamics of amino acid-derived urea synthesis in cirrhosis with mild or latent encephalopathy. The hepatic conversion of amino acids into urea was studied in eight patients with advanced cirrhosis under controlled conditions of substrate availability (continuous alanine infusion), before and after 3-month oral zinc sulfate supplementation (600 mg/d). Eight more patients, matched for hepatocellular failure and encephalopathy, served as controls. Plasma zinc levels were reduced in all patients and returned to normal after oral zinc. The alanine-stimulated urea nitrogen synthesis rate in relation to alpha-amino-N concentration--the functional hepatic nitrogen clearance--increased by 25% after zinc supplementation, i.e., more urea was produced at any alpha-amino-N concentration. Basal and alanine-induced glucagon decreased by 50%, and the ammonia response to alanine decreased by 30%. Psychometric tests improved, as did routine and dynamic liver function tests and the Child-Pugh score. Also, the plasma concentration of lipid peroxides was reduced by zinc. No significant changes were observed in the control group. Our data indicate that long-term oral zinc speeds up the kinetics of urea formation from amino acids and ammonia. Changes in the hormonal drive and/or the antioxidant activity of zinc might be involved in the general improvement in liver function, whereas the beneficial effects on encephalopathy might stem from decreased ammonia.
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PMID:Zinc supplementation and amino acid-nitrogen metabolism in patients with advanced cirrhosis. 862 Nov 38

Mitochondrial encephalomyopathy is a hereditary syndrome showing impairment of muscle and the central nervous system. In this disorder, the following three syndromes have been identified on the basis of characteristic symptoms: Kearns-Sayre syndrome (KSS), mitochondrial encephalomyopathy with lactic acidosis, and stroke-like episodes (MELAS), and myotonic epilepsy with ragged-red fibers (MERRF). In this report, we describe a case of mitochondrial encephalomyopathy with renal disease. A 25-year-old man was referred to our hospital in May, 1992 for evaluation of long-standing proteinuria. He had a small stature, exotropia and no pretibial edema. No mental retardation was observed. Urinary protein excretion was 2.0 g/day and urine sugar was negative. Laboratory examination revealed a serum urea nitrogen 19 mg/dl, and a creatinine value of 1.5 mg/dl. Creatinine clearance was 45.8 ml/min. His serum and spinal fluid lactate value were elevated. Biopsied muscle showed an absence of ragged-red fibers, and the presence of an A-to-G point mutation at nucleotide pari 3243 in the mitochondrial tRNA(Leu(UUR)) in peripheral blood leucocytes. He was thought to have MELAS. On the renal biopsy specimens, light microscopic examinations showed minor glomerular abnormalities with two glomerular collapses and tubulo-interstitial damage. Electron microscopic examinations showed partial thickening of the glomerular basement membrane. We report here this rare case of MELAS with renal disease, and also review seventeen cases of mitochondrial encephalopathy associated with renal disease. The existence of a relationship between mitochondrial disorder and renal damage remains obscure.
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PMID:[A case of mitochondrial encephalomyopathy (MELAS)]. 871 14

Uremic encephalopathy is a complication of renal failure that reflects stresses exerted by as yet poorly defined uremic toxins. All cells respond to stresses by undergoing the "heat shock" response. Although urea kinetics and creatinine concentration are routinely used to assess dialysis adequacy, the roles of urea and creatinine as uremic toxins remain controversial. To investigate their potential roles in uremic encephalopathy, cultured human neuroblastoma cells (SK-N-SH) were exposed to 0.5 to 14 mg/dL creatinine, or to 20 to 200 mg/dL urea, or to mannitol, NaCl, or glycerol at equivalent osmolalities for 30 min to 48 h, and the induction of Hsp72 (heat shock) protein was used as a marker of cell stress. Although creatinine failed to elicit a heat shock response, urea in clinically relevant concentrations (40 to 200 mg/dL) induced it at 30 min. The response peaked at 10 h and returned to zero by 48 h. Cells exposed to equivalent osmolalities of mannitol, NaCl, or glycerol failed to exhibit this response. Protein extracts from cells exposed to urea showed significant carbamylation that increased as a function of time. These results demonstrate: (1) that urea is neurotoxic in vitro and that creatinine is not: (2) that the insult urea causes is not simply the result of hypertonicity; but rather (3) that urea, via breakdown to cyanate and ammonium ions, may cause cell stress because of its ability to cause carbamylation of cellular proteins. The cells attenuation of the heat shock response after 10 h of exposure to urea suggests that they can adapt to the presence of urea or carbamylation. This may explain, in part, why the same degree of azotemia causes fewer neurological symptoms in patients with chronic as opposed to acute renal failure.
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PMID:Urea induces the heat shock response in human neuroblastoma cells. 878 97

Patients with hyponatremia are exposed to major neurological complications. On the one hand hyponatremia itself produces brain edema, increased intracranial pressure which potentially leads to subsequent neuropathological sequelae or death. On the other hand excessive correction could be followed by development of brain demyelinating lesions (central pontine or extrapontine myelinolysis) with major disability or fatal outcome. Understanding of brain adaptative mechanisms to changes in osmolality largely contributes to explain these neurological events. When serum sodium decreases, the brain prevents swelling by extruding electrolytes and organic osmolytes, a process almost fully achieved after 48 h. Conversely, during subsequent increase in serum sodium, reestablishment of intracerebral osmolytes occurs but their reuptake is more delayed (+/- 5 days). In both circumstances, these mechanisms can be overwhelmed, leading to brain damage. Acute hyponatremia (< 48 h) is generally hospital-acquired, mainly in the postoperative state and/or after excessive fluid administration. After abrupt fall in serum sodium, seizure, respiratory arrest and coma may develop and these manifestations are sometimes explosive in nature. Recognition of even minor symptoms is crucial and implies prompt correction. There is generally no risk of brain myelinolysis in acute hyponatremia. Some factors are suspected to aggravate the prognosis of hyponatremic encephalopathy, including female gender (menstruant women), hypoxia and young age. Chronic hyponatremia (> 48 h) usually develops outside the hospital and is generally better tolerated. The risks of brain myelinolysis can be largely reduced by limiting the correction level to < or = 15 mEq/1/24 h. However, if necessary, the initial rate of correction can be rapid provided that the final correction remains < 15 mEq/1/24 h. However, when other recognized risk factors for myelinolysis (hypokalemia, liver disease, poor nutritional state, burns) are present, correction should not exceed 10 mEq/1/24 h. Demyelinization is also observed in hypernatremia but it follows greater (50%) increase in serum sodium than from hyponatremic baseline. For symptomatic hyponatremia, rapid correction is usually obtained by hypertonic saline (3%) infusion. Another option consists in administration of intravenous or oral urea. Urea allows a rapid reduction of brain edema and intracranial pressure which is followed by subsequent correction of hyponatremia. Experimental data also suggest that treatment of hyponatremia with urea is associated with a lower incidence of myelinolysis. In hyponatremic patients without symptoms, there is no need for rapid correction and the treatment should be more conservative. Close monitoring of the serum sodium is indicated initially and if necessary, correction must be stopped and diuresis interrupted with dDAVP. Given recent experimental data, in patients overly corrected (delta SNa > 15 mEq/1/24 h), the risk of myelinolysis could be greatly reduced by rapidly decreasing the serum sodium through hypotonic fluids administration and dDAVP.
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PMID:Therapeutic recommendations for management of severe hyponatremia: current concepts on pathogenesis and prevention of neurologic complications. 887 50

Forty children with Reye syndrome (RS) or Reye-like illnesses were investigated to elucidate the underlying aetiologies. Extensive biochemical studies including patterns of organic acids and amino acids, liver histopathology, and, if available, a DNA approach were performed. In addition to classical RS (n = 10), the causes of Reye-like conditions included hereditary organic acidaemias (n = 13), urea cycle defects (n = 4), mitochondrial disorders (n = 3), fulminant hepatitis (n = 2), tyrosinaemia (n = 1), valproate-associated hepatotoxicity (n = 1), and other non-specific generalized organic acid disorders (n = 6). It is important to collect specimens when encephalopathy with liver dysfunction of unknown causes is noted. When the underlying inherited metabolic disorders are confirmed, the prevention of the recurrence by adequate diet control and medications, and genetic counselling become possible.
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PMID:Metabolic function and liver histopathology in Reye-like illnesses. 888 17

Noninvasive mechanical ventilation (NMV) now represents the first step in the management of acute on chronic respiratory failure (A/CRF). During the last 5 yrs, many studies have confirmed the feasibility of NMV in an acute setting, either by facial or nasal interface, used in addition to volumetric or barometric respirators, to manage A/CRF. The best indications for NMV are slowly progressive A/CRF, frequently represented by chronic obstructive pulmonary disease (COPD), or restrictive pulmonary disease. The criteria to initiate NMV in such patients are worsening of respiratory status and arterial blood gas (ABG) values, with increased hypoxia, hypercapnia and respiratory acidosis, despite optimal management with medication, physiotherapy and oxygen therapy. Respiratory encephalopathy is not an absolute contraindication; however, bronchial hypersecretion indicates that care is needed under NMV. Invasive mechanical ventilation with endotracheal (ET) intubation is discussed in the case of failure of NMV, when clinical status and ABG values worsen in spite of it. The signal for ET intubation is then obvious, represented by severe dyspnoea leading to respiratory pauses or arrest, severe cyanosis, and signs of haemodynamic instability. Despite immediate evidence of ominous cardiorespiratory inefficiency, ET intubation may be delayed and often avoided with the help of NMV. Criteria should be studied to identify guidelines for cessation of NMV, in order not to continue with the technique too long considering the safety of the patient. Indications for NMV in other kinds of ARF have received less study and are more controversial.
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PMID:Noninvasive mechanical ventilation and acute respiratory failure: indications and limitations. 915 23

Data were prospectively collected on 306 Kenyan children, including blood gases in 258 (75%). Severe malaria caused a predominantly high-anion-gap metabolic acidosis in at least 43% of children. Children with coma and respiratory distress (CM + RD) had greater evidence of renal dysfunction, lower mean pH and higher mean plasma osmolality than those with respiratory distress (RD) or coma (CM) as isolated findings (mean urea 10.7 vs. 6.0 vs. 4.3 mmol/l; mean creatinine 97 vs. 74 vs. 58 mumol/l; mean osmolality 301 vs. 288 vs. 283 mosmol/l; and mean pH 7.16 vs. 7.29 vs. 7.39, respectively, p < 0.001 for each comparison of CM + RD vs. RD or CM). In addition, children with CM + RD had a higher mean blood lactate (6.7 vs. 3.3 mmol/l, p < 0.001), a lower mean haemoglobin (5.5 vs. 7.0 g/dl, p = 0.002) and a lower mean age (26.4 vs. 41.9 months, p < 0.001) than children with CM and accounted for 15/24 (63%) of all deaths. These and previous data implicate hypovolaemia and renal impairment in the pathogenesis of metabolic acidosis in severe childhood malaria. In children who are acidotic, anaemia is strongly associated with lactic acidaemia and may therefore contribute to its pathogenesis. These data also imply that coma in acidotic children (CM + RD) and those with an isolated encephalopathy (CM) may result from quite different pathophysiological mechanisms.
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PMID:Acidosis in severe childhood malaria. 934 54

Chronic renal failure frequently causes uremic encephalopathy with impairment of different cognitive functions, but the pathophysiology of uremic encephalopathy is still unknown. We measured visually evoked event-related potentials (ERPs) in 33 neurologically asymptomatic patients before and after they underwent hemodialysis and compared their data with those of a strictly age-matched healthy control group. Before hemodialysis, the patients' P3 latency was significantly increased and P3 amplitude was significantly decreased as compared with that of the healthy control group. After hemodialysis, P3 latency of the patients showed a significant decrease (457+/-56 before and 438+/-54 ms after hemodialysis) and the P3 latency habituation during the ERP measurement was also significantly decreased. Patients with higher levels of blood urea nitrogen (BUN), creatinine, and uric acid performed better in ERP measurement than did patients with lower levels. Hemoglobin did not influence ERP latencies and amplitudes. Our data suggest that impaired cognitive processing can be disclosed by ERP even in neurologically asymptomatic chronic renal disease. Removal of uremic toxins by hemodialysis leads to an improvement in cognitive processing.
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PMID:Influence of end-stage renal failure and hemodialysis on event-related potentials. 950 13


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