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Biomedical subjects

T Sakurai

Publications and source records attributed to T Sakurai.

At least 505 records · Page 28Linked to original sources
PubMed1992

Effects of the new cognition-enhancing agent nefiracetam in rats with cerebral embolism.

The effects of nefiracetam (DM-9384, CAS 77191-36-7) on the learning behavior and cholinergic and GABAergic neuronal transmitter systems of rats with experimentally-induced cerebral embolism were investigated. Cerebral embolisms were induced in male Wistar rats by injection of 800 microspheres 50 microns in diameter via the left internal carotid artery under 2% halothane anesthesia. Daily oral administration of nefiracetam (30 mg/kg/d) was started 9 days after embolization. Nefiracetam caused significant (p < 0.05) improvement of deficits in the learning of both water maze and passive avoidance tasks beginning 22 days after embolization of the rats. The drug also significantly restored decreases in cortical choline acetyltransferase (p < 0.05) and hippocampal glutamic acid decarboxylase activities (p < 0.01) in the embolized cerebral hemisphere and significantly increased cortical choline acetyltransferase (p < 0.05) and acetylcholinesterase activities (p < 0.05) in the contralateral cerebral hemisphere 21 days after embolization. These results demonstrate that nefiracetam improves cognitive dysfunction in the late phase in embolized rats and suggest that the effect is at least partly due to the increase in glutamic acid decarboxylase, choline acetyltranseferase and acetylcholinesterase activities.

Acetylcholinesterase↗
PubMed1992

Thyroid function in premature infants.

The present study was performed using the simultaneous assays of free T4 and TSH levels in dried blood spots of filter paper for mass-screening of inborn errors of metabolism in order to clarify the thyroid function of premature infants. The subjects were divided in three groups: A group infants less than 1500 g at birth (n = 34, 27.4 +/- 2.6 weeks of gestational age), B group infants from 1500 to 2500 g at birth (n = 104, 35.6 +/- 2.4 weeks) and C group infants over 2500 g at birth (n = 490, 39.0 +/- 1.2 weeks). TSH levels were 4.51 +/- 3.03, 2.62 +/- 2.24 and 2.84 +/- 2.06 microU/ml in A, B and C group respectively and significant difference was recognized in group A and C. Free T4 levels were 0.71 +/- 0.42, 1.81 +/- 0.96 and 2.15 +/- 0.67 ng/dl, in group A, B and C respectively, and significant differences were recognized in all three groups. There was positive correlation between free T4 levels and gestational ages (Y = -2.413 +/- 0.11725X, r = 0.206, p less than 0.05).

Humans↗
PubMed1992

Abdominal aortic aneurysm due to congenital hypoplasia of the aortic media: a case report.

A 44 year-old woman with a family history of abdominal aortic aneurysm (AAA) underwent resection of an AAA. Histological examination revealed a lack of elastic fibers of the media and a diminished content of smooth muscle cells. A congenital hypoplasia of the aortic media was postulated as the etiology of this AAA. This condition may represent an aortic variety of medial defect observed in intracranial berry aneurysms, and be associated with a hereditary predisposition to AAAs.

Adult↗
PubMed1992

Carcinoid tumor of the pancreas with obstructive pancreatitis.

A case of primary pancreatic enterochromaffin cell (EC cell) carcinoid tumor in a 66-yr-old Japanese man is presented. The markedly dilated main pancreatic duct was noticed at the time of an incidental ultrasonogram during hospitalization for diabetes mellitus. Endoscopic retrograde pancreatography showed stenosis of the main pancreatic duct at the body of the pancreas and dilated pancreatic ducts distal to the obstruction. A distal pancreatectomy was performed, together with splenectomy. Macroscopically, the main pancreatic duct was compressed by a fibrous mass around the duct, and the pancreatic ducts distal to the tumor were markedly dilated. Histologically, the tumor was composed of uniform round cells, proliferating in small nests or trabeculae. The tumor cells were strongly positive with both Grimelius and Fontana-Masson stains. The immunohistochemical study disclosed the tumor cells to be positive for serotonin and chromogranin. This is a rare case of primary pancreatic EC cell carcinoid tumor with obstructive pancreatitis.

Aged↗
PubMed1992

A comparative study of once-a-day morning and once-a-day bedtime administration of 40 mg famotidine in treating gastric ulcers.

A randomized controlled study comparing once-a-day morning and once-a-day bedtime administration of 40 mg famotidine in treating gastric ulcers was carried out in 179 Japanese patients. Endoscopic examinations were performed at the baseline and repeated at 4-wk intervals until healing was confirmed. One hundred and sixty-four patients fulfilled the evaluation criteria (81 in the morning group and 83 in the bedtime group). The healing rates were 50.7% after 4 wk and 88.9% after 8 wk in the morning group and 46.5% after 4 wk and 74.7% after 8 wk in the bedtime group. The difference was statistically significant after 8 wk. Significant reductions from baseline for overall pain, beginning during the first 3 days, were likewise found in the two treatment groups. However, the pain severity in hunger state 1 wk after treatment was significantly higher in the bedtime group than in the morning group. Thus, once-a-day morning administration of 40 mg famotidine seems to be superior to once-a-day bedtime administration of 40 mg famotidine in treating gastric ulcers.

Adult↗
PubMed1991

The oxidative modification of low density lipoprotein by nonenzymatically glycated peptide-Fe complex.

Glycated polylysine, a model of glycated peptide, produces Fe(3+)-chelated compound, which could be converted to an active form in a nonenzymatic process. The exposure of human low density lipoprotein (LDL) to the active glycated polylysine-iron complex caused lipid peroxidation significantly higher than LDL exposed to Fe3+, accompanied by formation of fluorescence compound in apoprotein B (Ex.max. 360 nm, Em.max. 435 nm). Highly modified LDL, which can be judged by an obvious increase of fluorescence compound, could be easily endocytized by rat peritoneal macrophages. alpha-Tocopherol or probucol possessed powerful inhibitory action against active glycated polylysine-iron complex-induced lipid peroxidation of LDL. Each of intrinsic proteins tested, such as apotransferrin, ceruloplasmin and albumin, at the concentration of normal levels of human blood or at the lower levels, also exhibited inhibitory action on the lipid peroxidation of LDL.

Glucose↗
PubMed1991

Profiling of eicosanoids in inflamed gall bladder wall by gas chromatography with selected-ion monitoring.

The profiling of eicosanoids, including prostaglandin E2 (PGE2), prostaglandin F2 alpha (PGF2 alpha), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), thromboxane B2 (TXB2) and leukotriene B4 (LTB4), in dog and human gall bladders was carried out by a combination of an effective and convenient clean-up procedure and gas chromatography with selected-ion monitoring. The clean-up procedure was based on the stepwise elution of their methyl ester derivatives from a silica gel column with n-hexane-ethyl acetate and ethyl acetate-methanol in various ratios. The LTB4 methyl ester was eluted with an n-hexane-ethyl acetate (2:1, v/v) fraction because LTB4 is more lipophilic than the other eicosanoids. The present method permitted the quantitation of trace amounts of eicosanoids, including LTB4, present in tissues in the order of pg/mg of protein, without interference from other endogenous substances. In experimental acalculous cholecystitis produced in dog, the levels of eicosanoids (except LTB4) were significantly changed. Of these eicosanoids, the level of 6-keto-PGF1 alpha was significantly higher in the seromuscular layer and correlated with the observed severe morphological changes. In human chronic cholecystitis with gallstones, the level of 6-keto-PGF1 alpha in the mucosal layer was significantly higher than that in the seromuscular layer. These data suggest that prostaglandin I2 may play an important pathophysiological role in the course of cholecystitis.

6-Ketoprostaglandin F1 alpha↗
PubMed1991

The 5'-triphosphates of 3'-azido-3'-deoxythymidine and 2', 3'-dideoxynucleosides inhibit DNA polymerase gamma by different mechanisms.

Inhibition mechanisms of 5'-triphosphates of 3'-azido-3'-deoxythymidine (AZT-TP) and 3'-deoxythymidine (ddTTP) on extensively purified DNA polymerase gamma from bovine testes were examined by analysis of the products synthesized on singly primed M13 single-stranded DNA or synthetic oligonucleotide template-primer in the presence of analogues. The results indicate that AZT-TP inhibits DNA polymerase gamma in competition with dTTP but is not incorporated into DNA, whereas ddTTP is incorporated into DNA and causes chain termination. In contrast, both analogues were used by reverse transcriptase and caused chain termination.

Animals↗
PubMed1991

Comparison between the gelsolin and adseverin domain structure.

Adseverin (74-kDa protein, scinderin) is a calcium- and phospholipid-modulated actin-binding protein that promotes actin polymerization, severs actin filaments, and caps the barbed end of the actin filament, with its NH2-terminal half retaining these properties (Sakurai, T., Kurokawa, H., and Nonomura, Y. (1991) J. Biol. Chem. 266, 4581-4585). Further proteolysis of this NH2-terminal half generated five fragments, and two of them (Mr 15,000 and 31,000) showed Ca(2+)-dependent binding to monomeric actin. The Mr 31,000 fragment especially caused actin filament fragmentation, although its severing activity was also inhibited by several acidic phospholipids as was found in adseverin and its NH2-terminal half. Amino acid sequencing demonstrated that the two fragments' NH2 terminus were blocked in the same manner as the NH2 terminus of adseverin, and thus these two fragments are possibly located at the NH2-terminal of the adseverin molecule. This would then indicate that NH2-terminal fragments had a Ca(2+)-sensitive actin-binding function that relates to actin severing. The other two fragments' NH2-terminal sequencing showed a similar homology to the amino acid sequences of gelsolin and villin. Based on these observations, we propose that adseverin has a functional domain structure similar to that of the gelsolin and villin core.

Actins↗
PubMed1991

Cloning and functional expression of human cDNA for the ETB endothelin receptor.

We report the cloning of human cDNA encoding an ETB (non-isopeptide-selective) subtype of the endothelin receptor. The predicted amino acid sequence of the human ETB endothelin receptor was 87.8% and 62.9% identical with the previously cloned rat ETB and ETA receptors, respectively. COS cells transiently transfected with the cloned cDNA expressed specific, high-affinity binding sites for endothelin isopeptides and responded to the peptides with a transient increase of [Ca2+]i; endothelin-1 and endothelin-3 exhibited approximately equal potencies both in displacing 125I-labeled endothelin-1 binding and in eliciting [Ca2+]i transients. The ETB receptor mRNAs were expressed in various human tissues and also in the intact porcine aortic intimal cells ex vivo.

Amino Acid Sequence↗
PubMed1991

Chemical synthesis and biological activities of 6,6'-di-O-mycoloyl-beta,beta- and -alpha,beta-trehalose.

6,6'Di-O-mycoloyl-beta,beta-trehalose (beta,beta-TDM) and 6,6'-di-O-mycoloyl-alpha,beta-trehalose (alpha,beta-TDM) were synthesized and their toxicity and ability to activate peritoneal macrophages in situ were examined in mice, in comparison with 6,6'-di-O-mycoloyl-alpha,alpha-trehalose (TDM). Both beta,beta-TDM and alpha,beta-TDM caused a decrease in body weight two days after injection, however the weights reverted to a normal level. No deaths were caused by either analog. On the other hand, TDM showed potent toxicity, causing decrease in body weight and death of all animals injected. Beta,beta-TDM and alpha,beta-TDM were effective in the in situ activation of mouse peritoneal macrophages.

Animals↗
PubMed1991

Oxidative modification of glycated low density lipoprotein in the presence of iron.

This is the first observation for contributing to the glycation of low density lipoprotein (LDL) to oxidative modification of its own lipids and protein. Human plasma LDL was glycated by incubation with glucose (G-LDL). Glucose incorporated into apoprotein B was approximately 10 mol/mol of apoprotein (2.8% modification of lysine residues) and 84% of G-LDL was adsorbed on phenylboronate affinity column. G-LDL incubated with Fe3+ for 4 h caused a significantly higher level of lipid peroxidation than U-LDL (untreated with glucose), and a higher molecular weight protein was observed in apoprotein B on SDS-polyacrylamide gel electrophoresis (SDS-PAGE), increasing with incubation period. Corresponding to change on SDS-PAGE, G-LDL exposed to Fe3+ moved faster than G-LDL per se or U-LDL to anode on agarose gel electrophoresis. The higher the Fe3+ concentration, the more lipid peroxidation was caused. Alpha-tocopherol or probucol suppressed the lipid peroxidation of G-LDL exposed to Fe3+.

Electrophoresis, Polyacrylamide Gel↗
PubMed1991

The Ca2(+)-dependent actin filament-severing activity of 74-kDa protein (adseverin) resides in its NH2-terminal half.

Calcium sensitive actin severing protein, adseverin, with Mr 74,000, was cleaved into two fragments of Mr 42,000 and Mr 39,000 by V8 protease and trypsin, and both fragments were purified by high performance (pressure) liquid chromatography ion-exchange column chromatography. To understand how adseverin can sever actin filaments, we identified the actin-binding domains. The NH2 termini of native adseverin and the Mr 42,000 fragment were confirmed to be blocked by amino acid sequencing. Twelve amino acids of the Mr 39,000 fragment were sequenced from the NH2 terminus; the sequence of this part had a homology to the hinge region between segments 3 and 4 of gelsolin and villin. Thus, the Mr 42,000 fragment is the NH2-terminal half (N42), and the Mr 39,000 fragment is the COOH-terminal half (C39). Each fragment was examined for actin-severing, -nucleating, -capping, and phospholipid binding activities with and without calcium. N42 contained a calcium-dependent actin-severing activity regulated by phospholipid. C39 bound to G-actin in a calcium-dependent manner, but had no severing activity. The sequence homology and similar functional domain structure suggest a common structural basis for the calcium- and phospholipid-regulated actin-severing properties shared by adseverin, gelsolin, and villin.

Actin Cytoskeleton↗
PubMed1991

cDNA cloning, sequence analysis and tissue distribution of rat preproendothelin-1 mRNA.

We report the cloning of a full-length cDNA encoding rat preproendothelin-1 (preproET-1). The predicted rat preproET-1 consists of 202 amino acid residues and highly similar to human, porcine and bovine preproET-1, respectively. The deduced 21-residue sequence of mature rat ET-1 is identical to human, porcine, canine and bovine ET-1. As in other mammalian species, the mature ET-1 is predicted to be produced from a 39-residue big ET-1 in the rat. Northern blot analysis showed that a single 2.3-kb preproET-1 mRNA is expressed not only in vascular endothelial cells but also in other rat tissues, including the lung, brain, uterus, stomach, heart, adrenal gland and kidney. These findings suggest that ET-1 may play roles as a local mediator in multiple organs both within and outside the cardiovascular system in the rat.

Amino Acid Sequence↗
PubMed1991

Inhibitory effect of calcium-binding protein regucalcin on Ca2(+)-activated DNA fragmentation in rat liver nuclei.

Incubation of isolated rat liver nuclei with ATP, NAD+, and micromolar Ca2+ concentrations of various metal ions resulted in extensive DNA hydrolysis. Half-maximal activity occurred with 1.0 microM Ca2+ added, and saturation of the process was observed with 10 microM Ca2+. The Ca2+ (10 microM)-activated DNA fragmentation was inhibited by the presence of Ca2(+)-binding protein regucalcin isolated from rat liver cytosol. The inhibitory effect of regucalcin was complete at 0.5 microM. At 25 microM Ca2+ added, such an effect of regucalcin (1.0 microM) was not seen. Regucalcin also inhibited Ca2(+)-activated DNA fragmentation in the presence of calmodulin (10 and 20 micrograms). The results show that regucalcin can inhibit the Ca2(+)-activated DNA fragmentation due to binding the metal, suggesting a role in regulation of liver nuclear functions.

Adenosine Triphosphate↗