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T Yuki

Publications and source records attributed to T Yuki.

59 records · Page 4Linked to original sources
PubMed1980

Role of hormones in the mechanism of the swift increase in alcohol metabolism in the rat.

Gastric intubation of female Sprague-Dawley rats (80--150 g) with one large dose (5 g/kg) of ethanol doubled both hepatic oxygen uptake and ethanol metabolism within 2.5 hr in the perfused rat liver (Swift Increase in Alcohol Metabolism--SIAM). Hepatic oxygen uptake could also be elevated by direct infusion of epinephrine and glucagon into the perfused liver. Alcohol treatment produced significant increases in circulating epinephrine, norepinephrine and glucose but did not effect levels of plasma immunoreactive insulin. Administration of alpha- and beta-adrenergic blocking agents, adrenalectomy and hypophysectomy prevented the increase in oxygen uptake due to ethanol treatment. These data suggest that catecholamines and possibly other hormones play an important role in the mechanism of the Swift Increase in Alcohol Metabolism (SIAM).

Adrenalectomy↗
PubMed1976

Purification and properties of extracellular alpha-glucosidase of a thermophile, Bacillus thermoglucosidus KP 1006.

An extracecular alpha-glucosidase (alpha-D-glucoside glycohydrolase, EC 3.2.1.20) of a thermophile, Bacillus thermoglucosidius KP 1006, was purified about 350-fold. The purified enzyme had a specific activity of 164 mumol of p-nitrophenyl-alpha-D-glucopyranoside hydrolyzed per min at 60 degrees C and pH 6.8 per mg of protein. The molecular weight was estimated at 55 000. The pH and temperature optima for activity were 5.0--6.0 and 75 degrees C, respectively. Below 40 degrees C, the activity was less than 4.5% of the optimym. The enzyme showed a high specificity for alpha-D-glucopyranoside. The maximal hydrolyzing velocity per substrate diminished in the order: phenyl-alpha-D-glucopyranoside, p-nitrophenyl-alpha-D-glucopyranoside, isomaltose, methyl-alpha-glycopyranoside. The respective Km values were 3.0, 0.23, 3.2 and 27 mM. The activity was trace for turanose, and not detectable for sucrose, trehalose, raffinose, melezitose, maltose, maltotriose, phenyl-alpha-D-maltoside, dextran, dextrin and starch. Tris, p-nitrophenyl-alpha-D-xylopyranoside, glucose and glucono-delta-lactone blocked competitively the enzyme with respect to p-nitrophenyl-alpha-D-glucopyranoside. The Ki values were 0.12, 0.14, 2.2 and 2.4 mM, respectively. The activity was affected by heavy metal ions, but insensitive to EDTA, p-chloromercuribenzoate and iodoacetate. The enzyme was stable up to 60 degrees C, and inactivated rapidly at temperatures beyond 72 degrees C. The pH range for stability was 4.0--11.0 at 31 degrees C, and 6.0--8.5 at 55.5 degrees C. At 25 degrees C, the enzyme failed to be inactivated in 45% ethanol, in 7.2 M urea, and in 0.06% sodium dodecyl sulfate, but the tolerance was extremely reduced at 60 degrees C.

Bacillus↗
PubMedDate not supplied

The adaptive increase in ethanol metabolism due to pretreatment with ethanol: a rapid phenomenon.

Simple models were developed to study changes in oxygen uptake in perfused rat liver and increases in ethanol metabolism in vivo. Results obtained 2.5 hours following a large dose of ethanol were quantitatively similar to those seen after 24 hours or 5 weeks. The rapidity of the increase indicated that SIAM represents an activation rather than an adaptation. Pathways responsible for the swift increase in alcohol metabolism (SIAM) in the perfused rat liver were investigated through the use of ouabain and were found to be related to diminished glycolysis and another unidentified pathway. Investigation of pathways responsible for the increase in ethanol metabolism in vivo following ethanol treatment implicated the alcohol dehydrogenase pathway as that mainly responsible for the adaptive increase, although a catalase-H2O2-dependent component was also involved. The rate of NADH reoxidation generally appeared to be the rate-limiting step. In addition, the genetic aspect of SIAM was indicated through selective breeding resulting in F1 generations of non-SIAM and SIAM rats.

Alcohol Drinking↗
PubMedDate not supplied

Structure and function of the ftsH gene in Escherichia coli.

The ftsH mutant Y16 shows thermosensitive filamentation with reduced amounts of penicillin-binding protein 3 (PBP3) (Ferreira et al., 1987). Genetic analysis, however, showed that the lethality of the ftsH mutation was not due to a lack of PBP3 activity alone. The ftsH gene was cloned and sequenced and the FtsH protein was deduced to be a membrane protein of 70.7 kDa which has an ATP-binding domain. Highly significant homology of amino acid sequence was observed between FtsH protein and two eukaryotic proteins, yeast Saccharomyces cerevisiae Sec 18p and its mammalian homologue NSF, which are involved in protein transport pathways. This suggests that FtsH protein may act for translocation of specific proteins including PBP3 and at least one other additional protein essential for cell growth. Suppressor mutants of Y16, which were able to grow at 42 degrees C, were isolated, and the suppressor mutations (sfh) were mapped to 16 min. A wild type chromosomal fragment able to complement the sfh mutations was cloned. We also identified another gene (ftsJ) affecting cell division in the region upstream of the ftsH gene.

Bacterial Proteins↗