Search PubMed⌕ Search

Biomedical subjects

T Tsuchiya

Publications and source records attributed to T Tsuchiya.

At least 541 records · Page 30Linked to original sources
PubMed1989

Phosphorylation of paramyosin.

1. Myofibrils isolated from Mercenaria mercenaria were phosphorylated by endogenous kinase. Over a range of ionic strengths only paramyosin was phosphorylated. 2. Thiophosphorylation of paramyosin caused an inhibition of steady-state actin-activated ATPase activity of the myofibrils. 3. It is proposed that the endogenous kinase is the catalytic subunit of the cAMP-dependent protein kinase. 4. The sequence around the phosphorylation site was determined. 5. The phosphorylation site probably is close to the C-terminus of the paramyosin molecule.

Animals↗
PubMed1989

Correlation between the DNA damage in urinary bladder epithelium and the urinary 2-phenyl-1,4-benzoquinone levels from F344 rats fed sodium o-phenylphenate in the diet.

The relationship between urinary metabolites and DNA damage in the urinary bladder epithelium of male and female rats was tested by alkaline elution assay after an intravesical injection of OPP or its urinary metabolites. 2-Phenyl-1,4-benzoquinone (PBQ) revealed a weak DNA-damaging activity in both sexes at 0.05-0.1%. OPP and phenylhydroquinone (PHQ) had no effects at the same level. Histopathologically, a single intravesical injection of 0.1% PBQ induced epithelial hyperplasia of the bladder epithelium on day 5, but PHQ and OPP did not induce it. Feeding studies with OPP-Na were also performed to examine the correlation between urinary PBQ levels and DNA damage in bladder epithelium. Slight DNA damage was observed in males given 1.0 and 2.0% OPP-Na in the diet for 3-5 months. The damage was dependent upon the dietary levels of OPP-Na. The amounts of OPP, PHQ and PBQ in urine were well correlated with the dietary levels of OPP-Na for male rats. The amounts of OPP, PHQ and PBQ were greater in male rats than in females given 2.0% OPP-Na diet for 5 months. The urinary pH of males was slightly higher than that of females. Since 0.4% sodium bicarbonate did not cause DNA damage in the in-situ study, the urinary alkalinity may not affect the initiation steps of urinary carcinogenesis by OPP-Na. The present results indicate that the metabolite PBQ is the reactive species for the initiation steps of bladder tumors induced by OPP-Na and OPP.

Animals↗
PubMed1989

Purification and characterization of membrane-bound 5'-nucleotidase of Vibrio parahaemolyticus.

Membrane-bound 5'-nucleotidase from Vibrio parahaemolyticus was solubilized and purified using a nonionic detergent, heptyl-beta-D-thioglucoside, and was characterized. This enzyme required Mg2+ for activity, maximum activity being observed at 5 and 20 mM Mg2+ with AMP and ATP, respectively, as substrates. Of the divalent cations tested, Mn2+ and Co2+ were able to replace Mg2+ partially, whereas Ca2+ was ineffective. Zinc strongly inhibited the enzyme activity and Ni2+ caused partial inhibition. This enzyme required Cl- for activity, the optimal concentration being 20 mM or more. The order of effectiveness of anions was Cl- greater than Br- greater than I- approximately NO3-. Sulfate and acetate were ineffective. The optimal pH was 8.0. The activity of the purified enzyme was stimulated by the addition of lipid to the assay mixture. This enzyme hydrolyzed all 5'-nucleotides tested, but did not hydrolyze 3'-nucleotides or ribose 5-phosphate. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme appeared to be a single polypeptide, with a molecular weight of 72 kDa.

5'-Nucleotidase↗
PubMed1989

Cloning and expression of the 5'-nucleotidase gene of Vibrio parahaemolyticus in Escherichia coli and overproduction of the enzyme.

The gene encoding the membrane-bound 5'-nucleotidase of Vibrio parahaemolyticus was cloned and expressed in Escherichia coli. Cells of E. coli harboring a plasmid, pNUT5, which carries the 5'-nucleotidase gene were able to grow on ATP as the sole source of carbon, although the original cells were not. The 5'-nucleotidase activity was detected in whole cells of E. coli harboring pNUT5 and in membrane vesicles prepared from these cells. Most properties of the 5'-nucleotidase produced in E. coli, that is, its requirements for Cl- and Mg2+, substrate specificity, and inhibition by Zn2+, were similar to those observed in V. parahaemolyticus, but some alterations in properties were observed: The 5'-nucleotidase was partially inducible in V. parahaemolyticus, but its expression in E. coli was completely constitutive. The specific activity of the 5'-nucleotidase in membrane vesicles of E. coli harboring the plasmid was 30 times that observed in whole cells, whereas the specific activities in membrane vesicles and in whole cells of V. parahaemolyticus were almost the same. A new, dense band of protein with an apparent molecular mass of 63 kDa was detected when membrane proteins of E. coli harboring the plasmid were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

5'-Nucleotidase↗
PubMed1989

Co-amplification of c-myc and c-erbB-2 oncogenes in a poorly differentiated human gastric cancer.

c-erbB-2 oncogene has been reported to be frequently amplified in differentiated, tubular type of gastric cancer. Here we report a human gastric cancer which bore co-amplified c-myc and c-erbB-2 oncogenes: a portion of the amplified c-erbB-2 oncogene was found to be rearranged. Furthermore, c-myc and c-erbB-2 oncogenes were over-expressed in the tumor cells. In contrast to the previous reports, this gastric adenocarcinoma was classified as a poorly differentiated type, and was highly tumorigenic in nude mice. These results might suggest that activated c-myc and c-erbB-2 oncogenes co-operate and influence the malignant state of some gastric carcinomas.

Adenocarcinoma↗
PubMed1989

Effectiveness of sodium sugar sulfates on acute toxicity of paraquat in mice.

The reduction of acute toxicity of paraquat dichloride (PQ) in mice was studied by several sodium sugar sulfates such as dextran sulfate (DS), cellulose sulfate (CS), chondroitin sulfate (CDS), sucrose sulfate (SS) and glucose sulfate (GS). When sugar sulfates (DS, CS, SS or GS, 2,000 mg/kg) were given orally immediately after PQ ingestion (200 mg/kg), the survival rates were 100% respectively on the 14th day after PQ ingestion. In the case of CDS, it was 73%. The effective dose of SS and GS given for the prevention of PQ toxicity in mice after PQ (200 mg/kg) ingestion was more than 400 mg/kg for SS-treated group and more than 800 mg/kg for GS-treated group. The survival rate of these mice was 100% respectively. When GS or SS (2,000 mg/kg) was given orally to mice within 1 h (0, 10, 20, 30 or 60 min) after PQ ingestion (200 mg/kg), the survival rates in an earlier treatment were greater than those in a later treatment. The measurement of serum PQ concentrations in mice suggested that a mechanism for the prevention of PQ toxicity by the administration of sugar sulfates may be inhibition of PQ absorption, and/or stimulation of PQ excretion from intestine. The effectiveness of SS and GS in preventing PQ toxicity was similar to that of DS. These results suggested that SS, GS and DS might serve as an antidote for acute toxicity of PQ.

Animals↗
PubMed1989

Long-term effect of whole-body X-irradiation on cell-mediated immune reaction in mice.

Age-related change in immunological activity was examined at 10 to 91 weeks following whole-body irradiation by determining the specific anti-tumor cell-mediated immunity in host mice induced and/or enhanced by local irradiation to transplanted tumor. Median survival time of the non-irradiated C3H/He female mice was 98.6 weeks while the median life-span of the mice exposed to two and four Gy of 250kVp X-rays at the age of 10-12 weeks was shortened by 14.9 and 23.4 weeks, respectively. The rate of tumor reduction within two weeks after local irradiation to tumor and the growth inhibitory activity of spleen cells from tumor irradiated mice were reduced in a dose-dependent manner when assessed 10 weeks after whole-body irradiation, but recovered to the near-complete level of the non-irradiated controls within a few months, then gradually decreased with normal aging. These results suggest that the age-dependent decline of this immunological activity appears earlier in the irradiated mice as a result of whole-body X-irradiation at a young age, suggesting accelerated aging of the immune system.

Aging↗
PubMed1989

Penile vascular system of the dog. An injection-corrosion and histological study.

The vascular architecture of the dog penis was studied by resin casts and histological preparations. Morphological evidence was found for penile engorgement. The crus and the bulb were compressed by the ischiocavernosus and the bulbospongiosus muscles, respectively, indicating that these muscles act as a booster pump. The distal part of the bulb was also strangulated by the external anal sphincter, indicating that this muscle prevents blood in the corpus spongiosum penis from going back into the bulb. The common trunk of the dorsal vein of the penis was significantly occluded by the ischiourethralis muscle. The internal pudendal vein was also throttled by the levator ani, the coccygeus, and the internal obturator muscles. The extremely narrow diameter of each vein draining the erectile body was insufficient to drain the increased blood flow and, therefore, formed a sluice channel. It is inferred that these muscle activities and sluice channels facilitate the erection of the penis.

Animals↗
PubMed1989

Immunoreactive 7B2 concentrations in rats with various endocrine conditions.

Changes in 7B2 immunoreactivity in the pituitary as well as in the other brain regions and gut after various endocrine situations were investigated. Gonadectomy and neonatal monosodium glutamate (MSG) treatment resulted in an appreciable increase in the pituitary 7B2 concentration, though 7B2 content in the MSG treated pituitary was not significantly different when calculation was performed on a per pituitary gland basis. The 7B2 concentration in the cerebellum, midbrain and cortex in thyroxine treated rats showed a significant increase, which might indicate possible thyroid hormone involvement in 7B2 metabolism in the brain. The pituitary 7B2 concentration during the estrous cycle did not change significantly. These results suggest that pituitary 7B2 may correlate to the pituitary gonadotropins and that brain 7B2 content may be modulated by thyroid hormones.

Adrenalectomy↗
PubMed1989

Arterial-venous concentration gradient as a potential source of error in pharmacokinetic studies. Plasma concentration differences of 6-chloro-2-pyridylmethyl nitrate on constant infusion to rats.

1. Plasma concentrations of 6-chloro-2-pyridylmethyl nitrate (CPMN) at different sampling sites in the circulation were determined during and after constant infusion in the rat. 2. An arterial-venous CPMN concentration gradient was found and characterized by the following trends. During CPMN infusion into the right atrium, plasma concentrations were higher in arterial (aortic arch) than venous (inferior vena cava) plasma. After cessation of infusion the venous plasma concentrations were significantly higher (P less than 0.05) than those in arterial samples. There was a low concentration gradient between the right atrium and the peripheral artery, but substantial difference between the peripheral artery and the vein. There was a 1.8-2.4 extraction ratio of CPMN across the arterial-venous bed.

Animals↗
PubMed1989

[Survey of what dental students feel regarding their profession (3). The relation with their self concept].

The present survey was undertaken to find out how dental student feel about their profession and what type of the self concept they have. The subjects were 263 students in the 5th and 6th grades of dental school, Aichi-Gakuin University. The pattern of self concept as dental students or dentists was classified into three types, based on a survey of twenty statements test. These types were positive, negative and neutral. The results were as follows: 1. In both the 5th and 6th grades, statements about "present satisfaction as a dental student", in the 5th grade, "progress of university entrance examination", and in the 6th grade, "feelings about the scholastic side of dentistry", were strongly related to their type of self concept. But in both the 5th and 6th grades, there were few related statements about "the motive for entering the dental school" and "occupational choice after graduation". 2. In the result of the multivariate analysis Discriminant Analysis by the Second Class of Hayashi's Quantifying Theory, those students who were graded as "positive" had the following characteristics: (1) Regarding entrance examinations, they took only one examination for dental school when they entered. (2) When choosing dentistry as their occupation, they had not thought of it as a "self supporting occupation" or "occupation of high social standing". (3) Their present interest is learning about dentistry. (4) After their graduation from dental school, they would like to be professional dentists or, a practicing dentists or students of clinical dentistry in the hospital of the dental school.

Adult↗
PubMed1989

[Assessment of cerebral blood flow in intracerebral hematoma using IMP-SPECT].

To evaluate cerebral blood flow in intracerebral hemorrhage, we performed single photon emission computed tomography using N-isopropyl [I-123] p-iodoamphetamine (IMP-SPECT) in 20 patients. IMP-SPECT was carried out using rotating gamma camera at 30 min, and 4 hrs after injection. The results were compared with those by computed tomography (CT). In all cases, the extent of hematoma by IMP-SPECT was larger than that of CT. All cases were divided into 3 groups according to the extent of peripheral area zone of hematoma by IMP-SPECT. There were 10 cases with initial hypoperfusion and complete redistribution (Group I), 6 with initial perfusion defect and complete redistribution (Group II), 4 with initial perfusion defect and incomplete redistribution (Group III). Group III had extensive hematoma compared to Group I. The extent of peripheral area zone of hematoma could be considered as the decreased blood flow area by increased intracerebral pressure and the amplitude of redistribution may be correlated with celler damage. In conclusion, IMP-SPECT was useful to asses the viability of peripheral zone of hematoma.

Adult↗
PubMed1989

[Direct percutaneous transluminal coronary angioplasty (PTCA) for treatment of acute myocardial infarction: comparison with PTCA immediately after thrombolysis].

We studied 73 patients with acute myocardial infarction (AMI) treated by percutaneous transluminal coronary angioplasty (PTCA) without thrombolysis (direct PTCA) and 52 patients with AMI treated by PTCA immediately after thrombolysis (PTCR + PTCA). The initial results, angiographic findings and preservation of ventricular functions of the direct PTCA group were compared with those of the PTCR + PTCA group. 1. The success rate of coronary recanalization was higher in the direct PTCA group than in the PTCR + PTCA group, but there was no statistical significance (89% vs 77%; p = NS). 2. Major complications occurred in 4.1% of the direct PTCA group and in 5.8% of the PTCR + PTCA group (p = NS). 3. The incidence of acute coronary reocclusion was higher in the PTCR + PTCA group than in the direct PTCA group (7.4% vs 22%; p less than 0.05). 4. Angiographic haziness at the dilated site following PTCA was seen more frequently in patients in the PTCR + PTCA group than in those of the direct PTCA group (43% vs 23%; p less than 0.05). 5. Patients with haziness at the dilated site had a significantly higher incidence of acute coronary reocclusion than did the patients without such haziness (28% vs 6.3%; p less than 0.05). 6. Left ventricular ejection fraction and regional wall motion were better preserved in the direct PTCA group than in the PTCR + PTCA group, but there was not statistical significance. It was suggested that direct PTCA is safe and can be performed with good success rates. It is superior to PTCR + PTCA in avoiding acute coronary reocclusion, and thus we supposed that the response of lesions to angioplasty may be altered by the administration of thrombolytic agents.

Adult↗
PubMed1989

[Effects of early myocardial reperfusion on left ventricular function in patients with acute myocardial infarction].

The effect of early myocardial reperfusion (within six hours after the onset of symptoms) on left ventricular (LV) function in 106 patients with acute myocardial infarction was studied. The subjects consisting of 26 with conventional therapy, 19 with percutaneous transluminal coronary recanalization (PTCR), 16 with percutaneous transluminal coronary angioplasty (PTCA) after PTCR, 32 with direct-PTCA and 13 with coronary artery bypass graft (CABG) were randomly observed after 1981. In these patients, left ventricular ejection fraction (LVEF), regional wall motion, end-diastolic pressure and the contractility index were measured as the indices of LV function. 1. Compared to the conventional therapy group, LVEF and regional wall motion improved significantly in all groups with reperfusion therapy except in the PTCR group. This LV function in patients with subtotal obstruction or good initial collaterals significantly improved compared to patients with total obstruction and no collateral circulation. Patients with a 75 percent or more residual stenosis after reperfusion therapy had significantly decreased LV function compared to those with residual stenosis of less than 75 percent. These findings support the potential role for reperfusion therapy in patients with acute myocardial infarction.

Aged↗