Hepatic Glutamic Oxaloacetic Transaminase Research Articles

Crescimento e metabolismo do nitrogênio em juvenis de Trachinotus marginatus alimentados com diferentes níveis proteicos

O objetivo deste trabalho foi avaliar o crescimento e alterações no metabolismo do nitrogênio, além da composição do fígado e do músculo de juvenis de pampo Trachinotus marginatus alimentados com 43, 54 ou 64% de proteína bruta (PB43, PB54 e PB64, respectivamente). Grupos de 10 juvenis (1,47±0,14g) foram estocados em nove tanques de 50L, em sistema de recirculação de água marinha, durante 55 dias, alimentados quatro vezes ao dia com as rações pré-definidas. O ganho em peso, a taxa de crescimento específico e a conversão alimentar não apresentaram diferença significativa (P>0,05). Contudo, o acréscimo de proteína consumida aumentou o índice hepatossomático e a taxa de excreção de amônia pós-prandial, bem como diminuiu a retenção proteica. Os peixes alimentados com a dieta PB43 apresentaram menor concentração da transaminase glutâmico oxalacética hepática, além de menor concentração de triglicerídeos no músculo e fígado (P<0,05). A composição da carcaça, o teor de glicogênio e de proteínas totais para músculo e fígado não mostraram diferenças significativas (P>0,05), excetuando o maior teor de lipídios da carcaça no tratamento PB43. Concluímos que a melhor utilização da proteína por juvenis de pampo é observada quando eles são alimentados com uma dieta contendo 43% de proteína.

Dietary methionine requirement of juvenile blunt snout bream (Megalobrama amblycephala) at a constant dietary cystine level

A 9-week feeding trial was conducted to investigate the dietary methionine requirement of juvenile Megalobrama amblycephala at a constant dietary cystine level. Six semipurified diets were formulated to contain graded dietary methionine levels from 3.9 to 15.4 g kg−1 in about 2.5 g kg−1 increments in the presence of 2.2 g kg−1 cystine. Results showed that specific growth rate (SGR) and protein efficiency ratio (PER) significantly increased with increasing dietary methionine levels from 3.9 to 12.4 g kg−1 and thereafter kept stable. Maximum protein productive value (PPV), nitrogen retention efficiency (NRE) and liver weight were observed in 8.5 g methionine kg−1 diet. Protein contents in whole fish body were positively correlated with dietary methionine level, while lipid contents were negatively correlated with it. Morphological index and hepatic glutamate-pyruvate transaminase (GPT) activities were independent of dietary methionine levels. However, dietary methionine supplementation significantly improved haematological parameters, plasma methionine and total essential amino acid contents and hepatic glutamate-oxaloacetate transaminase (GOT) activities. Analysis of dose response using broken-line regression on the basis of SGR and PPV versus dietary methionine level estimated the optimum dietary methionine requirements of juvenile M. amblycephala to be between 8.5 and 8.4 g kg−1 of diet (25.0 and 24.7 g kg−1 of protein) in the presence of 2.2 g kg−1 cystine, respectively. Hence, the corresponding total sulphur amino acids requirements of this species were calculated to be 10.7 and 10.6 g kg−1 of diet (31.5 and 31.2 g kg−1 of dietary protein).

Hepatic tyrosine aminotransferase activity is affected by chronic heat stress and dietary tyrosine in broiler chickens

1. Two experiments were conducted to investigate the impact of high temperature and dietary tyrosine (Tyr) content on performance and activity of hepatic tyrosine aminotransferase (EC 2.6.1.5.), an enzyme that catalyses the first step in the metabolic degradation of Tyr in broiler chickens. 2. Two-week-old birds were allocated to one of three temperature treatments: 24 ° C (control), 36 ° C (heat stress, HS) and 24 ° C pair-fed (24PF) for 2 weeks and fed on diets containing 100% (Experiment 1) and 50, 100 and 200% (Experiment 2) of the NRC requirement for Tyr. 3. In Experiment 1, exposure of chickens to 36 ° C for 2 weeks caused significant increase in hepatic tyrosine aminotransferase activity but no significant change in activity of hepatic phenylalanine 4-hydroxylase (EC 1.14.16.1) (an enzyme that catalyses conversion of phenylalanine to Tyr) compared with the 24PF birds. No significant changes attributable to heat stress were detected in hepatic glutamic-oxaloacetic transaminase (EC 2.6.1.1) activity. 4. In Experiment 2, heat stress caused reductions in weight gain and feed intake in chickens on all diets, compared with their control counterparts. Hepatic tyrosine aminotransferase activity was increased by heat stress compared with their 24PF counterparts in chickens fed on the 100 and 200% Tyr diets, while in chickens fed the 50% Tyr diet, it was reduced by heat stress. 5. From these results, it is suggested that hepatic tyrosine aminotransferase activity is affected by heat stress and dietary Tyr content and the increased tyrosine aminotransferase activity with, in part, relatively low phenylalanine hydroxylase activity in hepatic tissues may be involved in the Tyr metabolism characteristic of heat-stressed chickens.

Liver damage by the crown-of-thorns starfish (Acanthaster planci) lethal factor

Upon autopsy of mice injected with the crown-of-thorns starfish (Acanthaster planci) lethal factor, a change in color of the liver, swelling of the gall bladder and jaundice were observed. After administration of the lethal factor into mice, activities of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), lactate dehydrogenase (LDH), acid phosphatase (ACP) and alkaline phosphatase (ALP) were significantly elevated in serum. Hepatic ALP also increased markedly but hepatic GOT, GPT and ACP showed a tendency to decrease. Activity of hepatic LDH first decreased and then returned to control level. Histopathological studies showed that severe degenerative changes such as enlargement and necrosis of hepatocytes were caused in the mouse liver by the lethal factor. These results strongly suggested that the A. planci lethal factor is a potent hepatotoxin.

Long-term starvation in Xenopus laevis daudin—III. Effects on enzymes in several tissues

1. 1. Adult, female Xenopus laevis were subjected to 12 months of starvation. 2. 2. Starvation resulted in a continuous reduction in the activity of both hepatic and renal glucose-6-phosphate dehydroganse. 3. 3. Fructose-1,6-diphosphatase was significantly reduced at months 10 and 12 in the liver, and at months 4, 10, and 12 in the kidney. 4. 4. Pyruvate kinase activity of muscle and liver decreased during the experimental period whereas the renal enzyme remained essentially unchanged. 5. 5. Both hepatic and renal glutamate-pyruvate transaminase (GPT) and hepatic glutamate-oxaloacetate transaminase (GOT) showed a reduction of activity after 2 and 4 months of starvation followed by an increase in GPT but not in GOT.

Short communication effects of six months' feeding of cypermethrin on the blood and liver of albino rats

A cypermethrin-mixed diet was fed uninterrupted to male albino rats for six months to evaluate toxicity in nontarget organisms. The rats consumed cypermethrin at a dose of 420 mg active ingredient (AI) per kilogram body weight per day. At the end of the stipulated period, the blood and liver were analyzed for insecticidal toxicity. The hemoglobin content and white blood cell (WBC) count remained unaltered, while the red blood cell (RBC) count and packed-cell volume (PCV) decreased significantly. The blood serum lactate dehydrogenase (LDH), isocitrate dehydrogenase (ICDH), and amylase activities were elevated 61%, 30%, and 46%, respectively, after six months of insecticide feeding, suggesting liver and possibly pancreas malfunction. The glutamate oxaloacetate transaminase (GOT) and creatine phosphokinase (CPK) activities, on the other hand, decreased 37% and 40%, respectively. The blood serum protein and free amino acids (FAA) content increased 12% and 31%, respectively, while cholesterol content decreased 49%. Consequent to cypermethrin administration the hepatic GOT, LDH, and ICDH activities increased 250%, 20%, and 30%, respectively. The soluble proteins, FAA, and glucose contents exhibited significant increases of 28%, 61%, and 71%, respectively. Histological changes were marked by hypertrophied hepatic cells and nuclei.

Hepatic Transaminase Activity in Alcoholic Liver Disease

Glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) activity were measured in precutaneous needle biopsy specimens of human liver tissue and compared with transaminase values in serum obtained on the day of biopsy. Hepatic GPT activity was significantly decreased in liver tissue of patients with alcoholic hepatitis and cirrhosis compared with the activity in individuals with normal livers (P less than 0.05) and individuals with primary biliary cirrhosis (P less than 0.05). The decreased hepatic GPT activity was not related to the presence of cirrhosis in biopsy specimens and was not increased by the addition of saturating amounts of pyridoxal phosphate to the assay mixture. Hepatic GOT was also slightly but significantly lowered in individuals with alcoholic liver disease (P less than 0.05). The GOT/GPT ratio in serum and liver tissue was increased only in individuals with alcoholic liver disease, but the increase did not reach statistical significance. The increased GOT/GPT ratio is due primarily to the low activity of GPT in liver and serum. The less than expected elevation of GPT in serum of patients with alcoholic hepatic reflects the diminished hepatic GPT activity and lesser amounts of this enzyme available to leak into serum from damaged hepatocytes.