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Biomedical subjects

N Takei

Publications and source records attributed to N Takei.

At least 181 records · Page 10Linked to original sources
PubMed1987

Enzymological characteristics of avian influenza A virus neuraminidase.

Neuraminidases of 18 strains of avian influenza A virus were examined by both colorimetric and fluorometric assays using fetuin and 4-methylumbelliferyl-N-Ac-alpha-D-neuraminide as substrates, respectively, to compare them with those of human influenza A and B viruses. The ratios of the neuraminidase activity of avian influenza virus measured by the colorimetric assay method to that measured by the fluorometric assay were distributed in the range of 2.4-20.3. The enzyme of avian influenza virus showed calcium-ion dependence in both assay methods. These results suggest that neuraminidase of avian influenza A virus is varies greatly from one strain to another in substrate specificity as compared with those of human influenza A and B viruses, and that some strains of avian influenza A virus have a neuraminidase with unique enzymological characteristics different from that of human influenza A virus as well as that of influenza B virus.

Colorimetry↗
PubMed1986

Ammonia detoxification by accelerated oxidation of branched chain amino acids in brains of acute hepatic failure rats.

BCAA aminotransferase and BCKA dehydrogenase activities are increased in the mitochondrial fractions from the brains of hepatic failure rats treated with two-thirds removal of CCl4-injured liver. Cerebral leucine decarboxylation was accelerated, and it well correlated with arterial blood ammonia levels. Elevation of brain ammonia content following an intraperitoneal injection of ammonium acetate to hepatic failure rats could be prevented by intravenous infusion of BCAA. Significantly increased brain glutamic acid, glutamine, and alanine contents were noted. These results suggested that accelerated brain BCAA catabolism in acute hepatic failure rats reduce the neurotoxicity of ammonia by promoting the synthesis of glutamic acid and glutamine from BCAA.

Acute Disease↗
PubMed1986

Blood to brain transfer of carbon tetrachloride and lipoperoxidation in rat brain.

[14C]-Carbon tetrachloride (CCl4) entered extensively into the liver and, to the small extent, into the brain 3 hr following the intragastric administration of the hepatotoxic dose. Although thiobarbituric acid (TBA) in the liver homogenates increased 12 hr after CCl4 administration, the brain showed little TBA values probably due to very low levels of chytochromes P-450 and b5 in the brain. These results suggest that CCl4 have no direct toxic effect upon the brain.

Animals↗
PubMed1985

Excitatory and inhibitory amino acid neurotransmitters and ammonia metabolism in hepatic failure rats.

The molar ratio of excitatory amino acid neurotransmitters (glutamate and aspartate) to inhibitory amino acid neurotransmitters (r-aminobutyric acid, GABA, and glycine) in the brain was diminished in acute hepatic failure rats with hyperammonemia, brain edema, and abnormal electroencephalograms. The ratio was further decreased with a marked elevation of arterial and brain ammonia levels 30 min after ammonium acetate was administered i.p. to hepatic failure rats. A continuous infusion of a branched chain amino acid (BCAA) solution before and after the ammonia loading effectively reversed the ammonia-induced lowering of this ratio; high ammonia contents in the brain were concomitantly decreased. Infusing glutamate instead of the BCAA solution failed to produce similar effects probably because of limited entry of glutamate into the brain. The above results suggest that excitatory and inhibitory amino acid neurotransmitter (glutamate, aspartate, and GABA) levels in the brain of hepatic failure rats might vary with abnormal cerebral ammonia metabolism.

Ammonia↗
PubMed1985

Enzymological heterogeneity of influenza B virus neuraminidase demonstrated by the fluorometric assay method.

The neuraminidase activity of 26 strains of influenza B virus isolated from all over the world was investigated colorimetrically, using fetuin as a substrate, and fluorometrically, using 4-methylumbelliferyl(4-MU)-N-Ac-alpha-D-neuraminide as a substrate, with special reference to enzymological heterogeneity. The activity of influenza A viral neuraminidases and of a commercially available pure viral one was strongly inactivated by either ethylenediaminetetraacetic acid or glycoletherdiaminetetraacetic acid, when measured by the fluorometric assay method, whereas that of influenza B ones was not at all. However, the viral neuraminidases of both influenza A and B viruses were found to be calcium ion-dependent by the colorimetric assay method. A difference in the catalytic rate between the two assay methods was observed with influenza B viral neuraminidase to a much greater extent as compared with that of influenza A. A difference in substrate specificity of these enzymes was demonstrated to be due to a difference in the degree of competitive inhibition by N-acetylneuraminic acid. These findings strongly suggest that enzymological heterogeneity in influenza B viral neuraminidase may be attributed to delicate structural differences, between the enzymes of influenza A and B viruses demonstratable only by the fluorometric neuraminidase assay method using 4-MU-N-Ac-alpha-D-neuraminide as a substrate.

Clostridium perfringens↗
PubMed1985

Interaction with deoxycholate of rat liver peroxisomal and cytosolic catalase.

Rat liver catalase was found to interact with deoxycholate (DOC). When purified, the peroxisomal catalase was precipitated at pH 6 in the presence of DOC, whereas in the peroxisomal extract (with DOC) it was unsedimentable at pH 6. The membrane fraction in the extract interacted with the catalase instead of DOC, and prevented the precipitation of catalase with DOC at pH 6. The peroxisomal catalase seemed to be easily modified by lysosomal protease during manipulation, and this proteolytic cleavage rendered the molecule able to interact with the membrane. On the other hand, the cytosolic catalase, both in the cytosol fraction and in the purified preparation, sedimented at pH 6 in the presence of DOC. The cytosolic catalase was far more resistant to proteolytic modification than the peroxisomal catalase. The molecule of peroxisomal catalase is assumed to have a site for recognizing the membrane, whereas such a structure may be absent in the cytosolic catalase or may not be easily exposed by proteolytic cleavage.

Animals↗
PubMed1985

Branched chain amino acid transaminase and branched chain alpha-ketoacid dehydrogenase activity in the brain, liver and skeletal muscle of acute hepatic failure rats.

Branched chain amino acid (BCAA) transaminase activity increased in both the mitochondrial and supernatant fractions of brain from hepatic failure rats, in which a partial hepatectomy was performed 24h following carbon tetrachloride (CCl4) administration, although the activity of liver and skeletal muscle was the same as in control rats. The elevation of mitochondrial BCAA transaminase activity in liver-injured rats was partly due to increased activity of brain specific Type III isozyme. Branched chain alpha-ketoacid (BCKA) dehydrogenase in the brain homogenates was not significantly altered in acute hepatic failure rats, while the liver enzyme activity was markedly diminished. BCKA dehydrogenase activity in the brain homogenates was inhibited by adding ATP to the assay system, and was activated in vitro by preincubating the brain homogenate at 37 degrees C for 15 min. These findings suggest that brain BCAA catabolism is accelerated in acute hepatic failure rats.

3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)↗
PubMed1985

[Study on the function of the sphincter of Oddi in patients with gallstone disease by dynamic hepatobiliary scintigraphy].

By using hepatobiliary scintigraphy, function of the sphincter of Oddi in 88 patients undergoing cholecystectomy with or without common bile duct exploration and T-tube drainage for gallstone disease was studied. These patients consisted of three groups; 57 patients with gallbladder stones (Group I), 25 with common duct stones migrated from the gallbladder (Group II) and 6 with primary common duct stones (Group III). Time-activity curves (T-A curve) obtained from the region of terminal end of the common bile duct were classified into 4 types which were different from each other. On the T-A curve, the rate of decrease (ROD, %) was defined as the difference between the count rate in the maximum and that at the 20 min after the maximum. The ROD in Group I was significantly greater than that in Group II or III (p less than 0.01). The ROD in Group II was also significantly greater than that in Group III (p less than 0.05). The increase of ROD in Group III after cholecystokinin-pancreozymin administration was less remarkable as compared with that in Group II. Thus, we conclude that the function of the sphincter of Oddi in these three groups may be different from each other.

Ampulla of Vater↗
PubMed1984

Characteristic features of plasma amino acid, plasma pancreatic glucagon, serum insulin concentrations in cirrhotic patients with histories of chronic alcohol consumption.

Plasma amino acid, plasma pancreatic glucagon and serum insulin levels were simultaneously measured in cirrhotic patients with (drinkers) and without a history of alcohol drinking (non-drinkers), as compared to those in alcoholics without liver disease. Clinical characteristics in drinkers and non-drinkers, such as the extent of liver dysfunction, which may affect plasma amino acid levels, were strictly matched. Plasma pancreatic glucagon levels in the drinker group were much higher than those in the non-drinker group. In the former group, the elevated plasma pancreatic glucagon levels were correlated (p less than 0.05) to total amino acid levels (the sum of 20 kinds of L-amino acid concentrations) and, elevated AAA concentrations leading to a diminished BCAA/AAA ratio. Drinkers with histories of hepatic encephalopathy presented grossly elevated glucagon levels and severely abnormal aminograms similar to those observed in hepatic insufficiency.

Adult↗
PubMed1984

Plasma amino acid imbalance in alcoholic liver cirrhosis.

Plasma amino acid concentrations and plasma glucagon and serum insulin levels were studied in male patients with compensated alcoholic and nonalcoholic liver cirrhosis. Age, nutritional status, and liver function tests were similar in both groups; none of the patients presented hepatic encephalopathy. Plasma valine and leucine concentrations were lower, and tyrosine, higher in alcoholic than nonalcoholic liver cirrhosis. As a result, the molar ratios of branched-chain amino acids (BCAA) to aromatic amino acids (AAA) were reduced markedly in this group. Although correlation coefficients comparing BCAA/AAA ratios and KICG in alcoholic and nonalcoholic liver cirrhosis were similar, a steeper regression line was observed in alcoholics. Plasma glucagon and proline levels were significantly higher in alcoholic than nonalcoholic liver cirrhosis, the former correlated with AAA concentrations only in alcoholic liver cirrhosis, but not with BCAA levels. These results indicated that alcoholic liver cirrhosis presented a more deranged plasma amino acid pattern than nonalcoholic, and the amino acid imbalances, except for depressed BCAA and elevated proline, were derived, in part, from the hyperglucagonemia.

Adult↗
PubMed1984

Glutamic acid and glutamine levels in serum and cerebrospinal fluid in hepatic encephalopathy.

Significant elevation of glutamic acid and glutamine concentrations in CSF was observed in hepatic encephalopathic patients with fulminant hepatitis and liver cirrhosis. However, the ratios of CSF glutamic acid to CSF glutamine levels and of CSF to serum glutamic acid and glutamine levels were significantly higher only in cirrhotic patients with hepatic encephalopathy. CSF glutamine levels were positively correlated with blood ammonia and CSF tyrosine levels in cirrhotic patients. The results indicate that CSF glutamic acid and glutamine levels are important tools in diagnosing hepatic encephalopathy in severe liver disease.

Adult↗