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Biomedical subjects

Y Moriyama

Publications and source records attributed to Y Moriyama.

At least 73 records · Page 4Linked to original sources
PubMed2000

Luminal acidification of diverse organelles by V-ATPase in animal cells.

Eukaryotic cells contain organelles bounded by a single membrane in the cytoplasm. These organelles have differentiated to carry out various functions in the pathways of endocytosis and exocytosis. Their lumina are acidic, with pH ranging from 4.5 to 6.5. This article describes recent studies on these animal cell organelles focusing on (1) the primary proton pump (vacuolar-type H(+)-ATPase) and (2) the functions of the organelle luminal acidity. We also discuss similarities and differences between vacuolar-type H(+)-ATPase and F-type ATPase. Our own studies and interests are emphasized.

Amino Acid Sequence↗
PubMed2000

Synaptic-like microvesicles, synaptic vesicle counterparts in endocrine cells, are involved in a novel regulatory mechanism for the synthesis and secretion of hormones.

Microvesicles in endocrine cells are the morphological and functional equivalent of neuronal synaptic vesicles. Microvesicles accumulate various neurotransmitters through a transmitter-specific vesicular transporter energized by vacuolar H(+)-ATPase. We found that mammalian pinealocytes, endocrine cells that synthesize and secrete melatonin, accumulate l-glutamate in their microvesicles and secrete it through exocytosis. Pinealocytes use l-glutamate as either a paracrine- or autocrine-like chemical transmitter in a receptor-mediated manner, resulting in inhibition of melatonin synthesis. In this article, we briefly describe the overall features of the microvesicle-mediated signal-transduction mechanism in the pineal gland and discuss the important role of acidic organelles in a novel regulatory mechanism for hormonal synthesis and secretion.

Glutamic Acid↗
PubMed2000

Cloning and sequencing of an endoglucanase gene from Scopulariopsis brevicaulis TOF-1212, and its expression in Saccharomyces cerevisiae.

The egI gene, encoding a major endoglucanase (EGI) of Scopulariopsis brevicaulis TOF-1212, was cloned and sequenced. The eglgene consisted of 868 bp with one intron and encoded a protein of 229 amino acids with a calculated molecular mass of 22,392 daltons. The EGI was assigned to a family 45 of glycosyl hydrolases and showed high similarity with other fungal endoglucanases, especially with those of Humicola grisea and Fusarium oxysporum, on the basis of hydrophobic cluster analysis. The egI gene was expressed under the promoter of the phosphoglycerate kinase gene (PGK) in Saccharomyces cerevisiae. The transformed cells were able to secrete the enzyme efficiently in an active form.

Amino Acid Sequence↗
PubMed2000

Overexpression and localization of heat shock proteins mRNA in pancreatic carcinoma.

In the present study we examined the localization and overexpression of heat shock proteins (hsps), mainly hsp90, in pancreatic carcinoma tissue compared with control tissue (including chronic pancreatitis and normal pancreas tissue), with the aid of immunohistochemical staining, in situ hybridization and reverse transcriptase polymerase chain reaction. Hsp90 alpha mRNA was overexpressed more highly in pancreatic carcinoma than in the control tissue. The proliferating-cell-nuclear-antigen labeling index was also high in pancreatic carcinoma tissue compared with the other tissue. These findings suggest that the overexpression of hsp90 alpha mRNA in carcinomas may be correlated with cell proliferation. However, hsp90 beta was constitutively overexpressed almost equally in all groups of pancreatic tissue including pancreatic carcinoma, chronic pancreatitis and normal pancreas tissue. Immunohistochemical staining demonstrated a differentiation in the expression of hsp90 between histological types of pancreatic carcinoma. These findings suggest that hsp90 alpha is involved in carcinogenesis and that hsp90 beta is correlated to structural conformation. Hsp90 alpha and hsp90 beta seem to perform different functions in tissue containing malignant cells. P53, MDM2 and WAF1, that were cell-cycle-related oncogene product were more strongly expressed in the nuclei of the cancer cells of the cancer tissue. Especially, MDM2 was more strongly expressed in mucinous carcinoma and the mucin secreting tissues surrounding pancreatic carcinoma tissue. The expression of MDM2 protein might also be correlated to secretion systems during structural conformation and be correlated to hsp90 beta.

Adenocarcinoma↗
PubMed2000

Morphometrical analysis of the relationship between Helicobacter pylori infection and pathological changes of gastric mucosa using Sano's 4 point biopsy method.

UNLABELLED: We examined Helicobacter pylori (H. p.) infection and changes in biopsied gastric mucosa as observed in biopsy specimens (inflammatory changes and atrophic changes) -with reference to their pathophysiological significance. We examined 68 patients with peptic ulcers and 19 patients with atrophic gastritis as controls. We confirmed H. p. infection of the gastric mucosa in biopsies from two points by tissue culture, microscopy and urease testing. We examined gastric mucosal flakes under microscopy, scoring the inflammatory changes and atrophic changes, from biopsies at Sano's 4 points. We compared the gastric mucosal condition of the H. p. (+) group and that of the H. p. (-) group histopathologically. The mucosal condition of the success fully treated H. p. infection group and that of the failure group were also investigated in the same way, as were the conditions before and after treatment. RESULTS: 1) The gastric mucosal inflammatory changes in the H. p. (+) group were more severe than those in the H. p. (-) group at all 4 biopsy points. 2) The gastric mucosal atrophy of the H. p. (+) group was more severe than that of the H. p. (-) group at all 4 biopsy points. 3) The gastric mucosal inflammatory changes in the treatment failure group were more severe than those in the Successful treatment group at all 4 biopsy points. 4) The gastric mucosal atrophy of the treatment failure group was more severe than that of the successful, treatment group at the anterior wall and the posterior wall of the body of the stomach. 5) The gastric mucosal inflammatory changes before treatment were more severe than those after treatment at all 4 biopsy points. 6) The gastric mucosal atrophy before treatment was more severe than that after treatment at the antrum and the angle of the stomach. DISCUSSION: H. p. infection seemed to cause changes in mucosal condition, severity of gastric mucosal inflammation and gastric mucosal atrophy at all 4 of Sano's points.

Adult↗
PubMed2000

Regulation of the activity and polymerization status of recombinant human cytosolic thymidine kinase by thiols and ATP.

The cDNA clone encoding human thymidine kinase (hTK), was expressed in E. coli using a prokaryotic expression vector, pKK 223-3. The kinetics of the recombinant hTK (rhTK) were similar to those of cytosolic TK but not of mitochondrial TK. rhTK was highly purified in the presence of either ATP or dithiothreitol (DTT). The specific activity of rhTK purified in the presence of ATP [rhTK(ATP)] was lower than that of rhTK purified in the presence of DTT [rhTK(DTT)]. Activity of the purified rhTK(ATP) was enhanced by addition of thiols including DTT, cysteine, homocysteine and beta-mercaptoethanol but inhibited by various sulfhydryl reagents such as 5,5'-dithio-bis(2-nitrobenzoic acid). Hence, it was suggested that rhTK is a thiol-type enzyme. Apparent Mr of purified rhTK(ATP) was 100 kDa, which corresponds to the size of a tetramer (25 kDa subunit), while that of purified rhTK(DTT) was 50 kDa, the size of a dimer. The tetramer form of rhTK(ATP) was converted to the dimer by replacement of ATP by DTT. On the other hand, the dimer form of rhTK(DTT) was converted to the tetramer by addition of ATP. Thus, the catalytic activity of human cytosolic TK might be regulated by thiols as well as ATP via its polymerization status.

Adenosine Triphosphate↗
PubMed2000

[Traumatic cardiac tamponade due to the nail stabbing].

A 45-year-old man was admitted to our hospital complaining of mild chest pain. The stab wound on the chest was very small and the nail had been completely buried under the skin. Emergency operation was mandatory for cardiac tamponade by the nail stabbing. Contused right ventricular wall was repaired using Teflon felt under cardiopulmonary bypass. It was important to have a suspicion as cardiac tamponade, when the patient showed uncertain hypotension.

Cardiac Tamponade↗
PubMed2000

[Perioperative risk factors in valve surgery concomitant with coronary artery bypass grafting].

Between January 1990 and December 1999, 20 patients underwent the valve surgery concomitant with coronary artery bypass grafting. There were 16 males and 4 females, their mean age was 66.5 years. Of the 20 patients, aortic stenosis was noted in 7, aortic regurgitation in 3, mitral stenosis in one, and mitral regurgitation in 9 patients. The cause of mitral regurgitation was considered to be an ischemic change in six patients, including ruptured papillary muscle due to myocardial infarction in two patients. On the contrary, LMT lesion was recognized in 5, LAD lesion in 17, LCX in 16, and RCA in 12 patients. Seven patients had preoperative myocardial infarction, three patients were required preoperative IABP support. AVR was performed in 10, MVR in 5, and MAP in 5 patients. The number of bypass was 1.9 +/- 0.85. Four patients died of LOS and MOF. The remaining 16 patients have been doing well. The significant difference between the survived and the not survived patients was recognized in the factor of emergency, preoperative IABP, papillary muscle rupture due to myocardial infarction, history of PTCA, LAD lesion, and the time of CPB. The factors regarding coronary artery had the influence on the outcome of a patients of valve surgery concomitant with CABG. Therefore, an appropriate myocardial protection and perioperative management for ischemia were mandatory.

Adult↗
PubMed1999

Hydroxyindole-O-methyltransferase is another target for L-glutamate-evoked inhibition of melatonin synthesis in rat pinealocytes.

Rat pinealocytes use L-glutamate as a modulator for melatonin synthesis. Upon binding of L-glutamate to the class II metabotropic glutamate receptor, norepinephrine (NE)-dependent formation of cAMP was inhibited, resulting in decreased serotonin-N-acetyltransferase (NAT) activity and melatonin output. Although L-glutamate at 1 mM caused 90% inhibition of melatonin synthesis, about 30% of the NAT activity remained, suggesting the presence of another target for L-glutamate. In this study, we found that L-glutamate also inhibits hydroxyindole-O-methyltransferase (HIOMT). The inhibition is reversible and dose-dependent: the maximal inhibition was obtained with more than 0.4 mM L-glutamate. Contrary to L-glutamate-evoked inhibition of NAT, agonists for class II metabotropic receptors such as (2S,2'R,3'R)-2-(2',3'-dicarboxycyclopropyl)glycine (DCG IV) had no effect on HIOMT. Neither (2S,3S,4S)-2-methyl-2-(carboxycyclopropyl)glycine (MCCG), an specific antagonist for class II mGluRs, nor dibutyryl cAMP restored the L-glutamate-evoked inhibition of HIOMT. Northern blot analyses revealed that L-glutamate significantly inhibits the expression of mRNA of NAT, but not that of HIOMT. These results indicated that HIOMT is an another target for L-glutamate due to its inhibition of melatonin synthesis, and the signaling pathway toward the inhibition is distinct from that of NAT.

Acetylserotonin O-Methyltransferase↗
PubMed1999

Circulating levels of secretory type II phospholipase A(2) predict coronary events in patients with coronary artery disease.

Background-The circulating levels of secretory nonpancreatic type II phospholipase A(2) (sPLA(2)) are increased in various chronic inflammatory diseases and the increase in the levels correlates with the disease severity. sPLA(2) may possibly play a role in atherogenesis and is highly expressed in atherosclerotic arterial walls that are known to have inflammatory features. Thus, this study prospectively examined whether circulating levels of sPLA(2) may have a significant risk and prognostic values in patients with coronary artery disease (CAD). Methods and Results-Plasma levels of sPLA(2) were measured in 142 patients with CAD and in 93 control subjects by a radioimmunoassay. The sPLA(2) levels had a significant and positive relations with serum levels of C-reactive protein, a marker of systemic inflammation, and with the number of the traditional coronary risk factors associated with individuals. Multivariate logistic regression analysis showed that higher levels of sPLA(2) (>246 ng/dL; 75th percentile of sPLA(2) distribution in controls) were a significant and independent risk factor for the presence of CAD. In multivariate Cox hazard analysis, the higher levels of sPLA(2) were a significant predictor of developing coronary events (ie, coronary revascularization, myocardial infarction, coronary death) during a 2-year follow-up period in patients with CAD independent of other risk factors, including CRP levels, an established inflammatory predictor. Conclusions-The increase in circulating levels of sPLA(2) is a significant risk factor for the presence of CAD and predicts clinical coronary events independent of other risk factors in patients with CAD; these results may reflect possible relation of sPLA(2) levels with inflammatory activity in atherosclerotic arteries.

Aged↗
PubMed1999

Association of plasma levels of activated protein C with recanalization of the infarct-related coronary artery after thrombolytic therapy in acute myocardial infarction.

Protein C is one of the most important antithrombotic components. After activation by the thrombin-thrombomodulin complex on endothelial cells, activated protein C (APC) inactivates factors Va and VIIIa, which leads to the inhibition of thrombin formation. We examined the association of plasma levels of APC with the responsiveness to coronary thrombolytic therapy of the infarct-related coronary artery in patients with acute myocardial infarction (AMI). Plasma levels of APC, thrombin-antithrombin III complex (TAT), and plasminogen activator inhibitor (PAI) activity were measured in 32 consecutive AMI patients who underwent coronary angiography followed by thrombolytic therapy, and compared to the measurements in 23 control subjects. On admission, APC levels (ng/mL) were significantly elevated in patients with AMI, as compared with controls (2.5+/-0.4 vs. 1.2+/-0.2, 1.3+/-0.2, respectively, p<0.01). At discharge, plasma levels in AMI patients decline to values not significantly different from those in controls. (1.2+/-0.2, 1.3+/-0.2, respectively). TAT levels (ng/mL) were different among the groups in a fashion similar to that of APC (14.1+/-3.1 on admission vs. 3.3+/-0.4 at discharge, 1.8+/-0.1 in the control subjects, respectively, p<0.01). PAI activity levels (IU/mL) were higher on admission than at discharge and higher than the control subjects (19.7+/-1.8 vs. 10.5+/-1.0, 5.4 +/- 0.7, respectively, p<0.01). Thirty-two patients with AMI were classified into two groups according to the results of thrombolysis: the success group (24 patients) and the failure group (eight patients). APC levels were higher in the failure group than in the success group (5.1+/-0.7 vs. 1.6+/-0.2, p<0.01). TAT levels were also higher in the failure group than in the success group (30.8+/-9.6 vs. 8.6+/-1.7, p<0.01). PAI activity levels (IU/mL) were lower in the failure group than in the success group (13.5+/-3.1 vs. 21.7+/-2.1, p<0.05). There were correlations between APC and TAT levels both on admission (r=0.75, p<0.0001) and at discharge (r=0.71, p<0.0001). Elevated APC was thought to correlate with increased thrombin generation in patients with AMI. This study demonstrated that there was a significant relation between plasma APC level and the responsiveness to thrombolytic therapy of the infarct artery. This study may also indicate that increased thrombin generation is a cause of the resistance to thrombolytic therapy.

Acute Disease↗
PubMed1999

D-aspartate is present in human retinoblastoma Y79 cells.

In mammals, D-aspartate is present in various neuroendocrine cells, being especially abundant in pinealocytes. Although D-aspartate is suggested to be involved in some neuroendocrine function, little is known about its origins as well as its physiological roles. In the present study, we found that an appreciable amount of D-aspartate (50.8 pmol/1 x 10(6) cells) is present in clonal human retinoblastoma Y79 cells. The amount of D-aspartate corresponds to 28% of that in rat pinealocytes. The D-aspartate concentration did not change with the culture duration or passage, suggesting de novo biosynthesis of it. Thus, Y79 cells may constitute a suitable experimental system for studies on the biogenesis and signal transduction of D-aspartate in mammalian cells.

Animals↗
PubMed1999

Functional expression of metabotropic glutamate receptor type 5 in rat pinealocytes.

Mammalian pinealocytes, endocrine cells for melatonin, express class II metabotropic glutamate receptors (mGluRs), which are involved in negative regulation of melatonin synthesis through an inhibitory cAMP cascade. We investigated whether mGluRs other than class II receptors are expressed in rat pinealocytes. RT-PCR analysis and Northern blotting indicated that the mRNA of mGluR5, a class I receptor, was present in pineal glands. Quisqualate and 1-aminocyclopentane-1,3-dicarboxylate (1S,3R-ACPD), class I receptor agonists, increased the intracellular [Ca2+] of fura-2 loaded cultured pinealocytes in the absence of extracellular Ca2+ which is blocked by methylcarboxyphenylglycine, a class I receptor antagonist. These results suggest that mGluR5 is functionally expressed in pinealocytes and triggers Ca2+ efflux from intracellular stores.

Animals↗
PubMed1999

Possible contribution to hepatocarcinogenesis of X transcript of hepatitis B virus in Japanese patients with hepatitis C virus.

Serological research suggests that hepatitis B virus (HBV) and hepatitis C virus (HCV) are associated with the development of hepatocellular carcinoma (HCC). It is unclear how genes of hepatitis viruses participate in hepatocarcinogenesis in patients infected with HCV. We investigated the expression of hepatitis virus-related RNAs in resected liver from 51 patients with HCV antibodies (Ab) and without hepatitis B surface antigen (HBsAg). mRNA transcripts of the genes HBx, HBc, HBs, nonstructural (NS) region 3 of HCV, the 5'-untranslated region (UTR) of HCV, and the 5'-UTR of hepatitis G virus (HGV) were amplified by reverse-transcription polymerase chain reaction (RT-PCR) with specific primers for each gene. The HBx transcript was detected in 19 (37%) tumors and in 8 (16%) specimens of noncancerous tissues (P =.014). The NS3 gene of HCV was detected in 35 (69%) tumors and 41 (80%) noncancerous tissues. HGV RNA was detected in 3 tumors (6%). Patients with HBx transcripts were younger than patients without HBx transcripts (P =.012). HBx transcripts were detected in 3 (33%) of 9 well-differentiated HCCs, in 8 (31%) of 26 moderately differentiated HCCs, and in 8 (50%) of 16 poorly differentiated HCCs. Codon 130 (AAG) and codon 131 (GTC) of HBx were changed to ATG and ATC, respectively, in all HCCs with HBx transcripts. In conclusion, we found that the HBx gene was expressed in many HCCs; the gene might promote hepatocarcinogenesis in patients with HCVAb and without HBsAg, but HGV is not closely related to hepatocarcinogenesis in such patients.

Base Sequence↗
PubMed1999

Application of a manifold system for temporary reperfusion during proximal anastomoses in conventional coronary bypass surgery.

We report the application of a manifold system which is attached to saphenous vein grafts after the completion of distal coronary anastomosis. This technique permits not only the direct delivery of cardioplegic solution into the distal coronary artery, but also the reperfusion of revascularized coronary arteries via saphenous vein grafts by changing the connection to the arterial circuit during proximal anastomosis under a partial occlusion of the aorta in conventional coronary artery bypass surgery.

Cardioplegic Solutions↗