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Biomedical subjects

Y Takata

Publications and source records attributed to Y Takata.

At least 289 records · Page 16Linked to original sources
PubMed1979

Effects of angiotensin II and 1-sar., 8-isoleu. angiotensin II on electrical and mechanical properties of the portal vein from rats of different ages.

The effects of angiotensin II (Ag-11) and 1-sar., 8-isoleu. angiotensin 11 (anti-Ag-11) on the membrane and mechanical properties of smooth muscle cells of the rat portal vein were investigated in three different age groups (6--8 weeks, immature rat; 3--5 months old, young rat and 13--15 months old, adult rat). Application of Ag-11 (10(-10) g/ml) did not depolarize the membrane, but did increase the spike frequency and potentiated the frequency and amplitude of twitch contraction. In a concentration of more than 10(-9) g/ml Ag-II, the membrane was depolarized and a phasic contracture was developed in three age groups. Depolarization of the membrane produced by Ag-II could be classified into two components, i.e. phasic and tonic depolarizations. In adult rats, Ag-II produced the highest amplitude of the depolarization in three age groups but tonic depolarization showed nearly the same amplitude of smooth muscle cell membrane to Ag-II increases with age up to 3--5 months and that an increased sensitivity is accompanied by a generation of desensitization. Tachyphylaxis to Ag-II was also observed by repetitive applications, but the appearance depended on the stimulus conditions. Anti-Ag-II, itself slightly increased the spike frequency and the amplitude of twitch contraction. However, under pretreatment with anti-Ag-II (10(-9) or 10(-7) g/ml), the actions of Ag-II on the electrical and mechanical activities were markedly suppressed in the three age groups. When the dose-response curve was obtained from the mechanical response produced by Ag-II, the relation shifted to the right in the presence of anti-Ag-II in all age groups. In the presence of 10(-7) g/ml anti-Ag-II, no contracture was evoked by application of 10(-6) g/ml Ag-II in three age groups. Anti-Ag-II seems to possess a higher affinity to the angiotensin receptor than does Ag-II.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1979

Serum prolactin responses to TRH in recurrent breast cancer patients.

The response of serum prolactin (PRL) to thyrotropin-releasing hormone (TRH) was evaluated by radioimmunoassay in 6 normal women and 44 breast cancer cases. They were divided into the following 5 groups: group 1:6 normal women; group 2:10 preoperative patients with early breast cancer; group 3:13 preoperative patients with advanced cancer; group 4:13 postoperative patients with no recurrence of cancer for more than 2 years; group 5:8 postoperative patients with cancer recurrence. The maximum increment of serum PRL levels following the administration of TRH was significantly higher in groups 2, 3 and 5 than in groups 1 and 4. These results indicate that patients with recurrent breast cancer have a higher PRL response to TRH than those without recurrence of cancer.

Breast Neoplasms↗
PubMed1979

High-performance liquid chromatography for ultraviolet-absorbing constituents in human urine.

Several liquid-chromatographic systems involving anion-exchange resins and linear acetate gradient elution have been reported previously for the analysis of ultraviolet-absorbing constituents in human urine. We describe a high-performance liquid-chromatographic system on which a macroreticular anion-exchange resin, and stepwise elution are used. Separations were more rapid with ammonium chloride/acetonitrile stepwise elution than with acetate stepwise elution, and urine constituents could be detected at 225 nm with the former system. Analytical conditions were convenient and the method has proven to be useful for routine clinical analysis.

Acetonitriles↗
PubMed1977

Effects of metiamide and propranolol on gastric secretion in anesthetized dogs.

The effects of metiamide, a histamine H2-receptor antagonist, and propranolol, a beta-adrenergic blocking agent, on gastric secretion were studied in anesthetized dogs. Metiamide, 1.45 mg/kg i.v., markedly inhibited the gastric secretion induced by a continuous i.v. infusion of tetragastrin (8 microng/kg-hr), histamine dihydrochloride (160 microng/kg-hr), or methacholine bromide (100 microng/kg-hr). Propranolol 0.5 or 1.0 mg/kg i.v. produced a significant potentiation of tetragastrin-induced gastric secretion but no influence of the secretion induced by methacholine. Propranolol at 5 or 10 mg/kg i.v. produced a slight reduction of the tetragastrin-induced secretion and a significant reduction of methacholine-induced secretion. Histamine-induced gastric secretion was not affected by propranolol at either 1 and 10 mg/kg i.v. These findings lend support to the hypothesis that interactions among histamine, gastrin and acetylcholine receptors do occur though the degree would not be the same in all directions.

Animals↗
PubMed1976

Effects of carbenoxolone Na on acute and chronic gastric ulcer models in experimental animals.

Effects of carbenoxolone Na on acute or chronic types of gastric lesions or ulcer models produced in rats, guinea pigs, or dogs were studied. Carbenoxolone Na, given either orally or intraperitoneally, produced a significant inhibition of stress-induced gastric lesions in intact or in pylorus-ligated rats. Acetylsalicylic acid (ASA)-induced or serotonin-induced gastric lesions in rats were also inhibited significantly by pretreatment with the drug. However, carbenoxolone Na did not affect the development of Shay ulceration in rats even though the peptic activity in gastric juices was markedly reduced by the drug. Histamine-induced gastric lesions in guinea pigs were not prevented by pretreatment with carbenoxolone Na. Although carbenoxolone Na, given for 10-20 days, did not promote the healing of stress-induced gastric lesions and acetic acid gastric jlcers in rats, it significantly accelerated the healing of chronic gastric ulcer produced in dogs by 3 weeks' treatment. Carbenoxolone Na prevented the acid back-diffusion caused by ASA without any influence on Na+ efflux in pylorus-ligated rats.

Acute Disease↗
PubMed1976

Effects of L-glutamine on various gastric lesions in rats and guinea pigs.

Effects of L-glutamine on gastric lesion models in rats and guinea pigs were studied. Shay ulceration in rats was not inhibited by oral L-glutamine. Although stress-induced gastric lesions in intact rats were not inhibited by L-glutamine, a strong antagonism of gastric lesions was induced in pylorus-ligated rats under the same stress by the amino acid. Histamine-induced gastric lesions in intact rats and guinea pigs were also markedly inhibited by L-glutamine. L-Glutamine inhibited the gastric lesions in rats induced by compound 48/80 but not significantly. Reserpine- or serotonin-induced gastric lesions in rats were not affected by L-glutamine. The mechanism of L-glutamine protection was discussed.

Animals↗
PubMedDate not supplied

Crystallization and preliminary X-ray diffraction studies of glycine methyltransferase from rat liver.

Glycine methyltransferase from rat liver is a tetrameric enzyme with 292 amino acid residues in each identical subunit and catalyzes the AdoMet-dependent methylation of glycine to form sarcosine. The enzyme was crystallized by the hanging drop vapor diffusion method, using polyethylene glycol 4000 as a precipitant. The crystal belongs to the orthorhombic space group P2(1)2(1)2, with unit cell dimensions of a = 86.4, b = 175.7, c = 45.5 A and with two subunits in the asymmetric unit. The crystals diffract beyond 2.4 A resolution, and a set of 2.4 A resolution data were measured.

Animals↗
PubMedDate not supplied

Metabolism of a mutant insulin by a receptor-mediated process and an insulin degrading enzyme.

The metabolism of a mutant insulin, [LeuB25]-insulin, was studied in vitro and in vivo. Porcine or mutant insulin (4 micrograms/kg body weight) was injected i.v. into streptozotocin-induced diabetic rats and their plasma glucose and insulin levels were determined. The half-lives of porcine and mutant insulin were 3 min and 18 min, respectively. The ability of the mutant insulin to lower the blood glucose levels was 38% of that of normal when the glucose levels at the nadir were compared. Receptor-mediated degradation of the mutant insulin assessed by chromatography of the degraded materials in the media after incubation with cells was less compared with that of porcine insulin (4% vs. 24%). The media containing the insulin degrading enzyme (IDE) of IM-9 cells and rat livers degraded porcine and mutant insulin to the same extent. These results suggest that the decreased clearance of insulin is due to the decreased receptor binding and the decreased receptor-mediated degradation, but is not due to the decreased degradation by IDE.

Animals↗
PubMedDate not supplied

Insulin binding to differentiating muscle cell line L6.

We studied insulin binding to cultured differentiating muscle cell line L6. Insulin binding to the cells reached a plateau after incubation with 125I-insulin for 4 h at 22 degrees C, and was at an optimum at pH 7.8. Preincubation with 10 microM of hydrocortisone for 36 h at 37 degrees C resulted in significantly increased insulin binding (1.73 +/- 0.12 ng/mg protein for treated cells vs. 1.13 +/- 0.025 ng/mg protein for control cells, mean +/- SD, P less than 0.001). Preincubation with 1 microM of hydrocortisone or 1 microM of dexamethasone also led to increased binding. The number of insulin-binding sites per cell increased 2.5-fold in glucocorticoid-treated cells (9.7 X 10(3) sites/cell for treated vs. 3.8 X 10(3) sites/cell for control cells). Preincubation with trifluoperazine (5 microM), a calmodulin inhibitor, did not affect insulin binding to the cells. These results indicate that glucocorticoid might have some important role in regulating the number of insulin receptors in L6 muscle cells.

Animals↗
PubMedDate not supplied

The use of deblurring technique for improving the longitudinal resolution in helical CT of the head and neck region.

We evaluated the use of deblurring technique by digital deconvolution for improving the longitudinal resolution in helical CT in a phantom and CT images of head and neck patients. After performing the helical scanning, overlapped axial images were reconstructed at 1/10 of the actual collimation. Then, the deblurring technique was performed. Results revealed that the resolution of slice profiles was improved after deblurring. Further, the longitudinal resolution increased as the strength of the deconvolution increased, at the expense of an increase in helical artifacts. The sharpness and visualization of horizontally running structures were improved in the reconstructed MPR, MPVR, MIP and 3D images in both the phantom and the images of all patients. Also, visualization of the peripheral vessels in CTAs was improved.

Angiography↗
PubMedDate not supplied

Development of the NIST bone ash standard reference material for environmental radioactivity measurement.

The bone ash standard reference material (SRM), a blend of 4% contaminated human bone and 96% diluent bovine bone, has been developed for radiochemical method validation and quality control for radio-bone analysis. The massic activities of 90Sr, 226Ra, 230Th, 232Th, 234U, 235U, 238U, 238Pu, (239 + 240)Pu and (243 + 244)Cm were certified using a variety of radiochemical procedures and detection methods. Measurements confirmed undetectable radionuclide heterogeneity down to a sample size of 5 g. thereby implying adequate blending of particulate materials with dilution factors of up to 17,900. The results among most of the intercomparison laboratories and their methods were consistent. Disequilibrium was observed for decay chains: 234U(0.67 mBq/g)-230Th(0.47 mBq/g)-226Ra(15.1 mBq/g)-210Pb(23 mBq/g)-210Po(13 mBq/g) and 232Th(0.99 mBq/g)-228 Ra(6.1 mBq/g)-228Th(7.1 mBq/g). The disequilibria were the results of mixing occupationally contaminated human bone with natural bovine bone and the fractionation during internal biological processes. The massic activity of 210Pb, 228Th and 241Am were not certified because of insufficient 228Ra and 241Pu data and lack of knowledge in how 222Rn and its daughters will be fractionated in the SRM bottle over time.

Animals↗
PubMedDate not supplied

Haemodynamic and humoral consequences of chronic infusion of vasopressin in conscious rats.

1. To determine the long-term haemodynamic and humoral effects of arginine vasopressin (AVP), a chronic intravenous infusion of AVP was performed in conscious Wistar normotensive rats. 2. AVP (1, 10, 50 or 100 ng/h) or saline as a vehicle control was infused continuously into the right jugular vein at a rate of 1 microL/h using an osmotic minipump for 7 days. 3. As a result, significant elevations of systolic blood pressure were observed in association with increases in plasma AVP concentration. Significant decreases in heart rate were observed during infusion of 100 ng/h of AVP. Mean arterial pressures measured directly on the sixth day of infusion were significantly higher in the rats given 50 ng/h (125 +/- 3 mmHg) or 100 ng/h (125 +/- 2 mmHg) compared with control rats (117 +/- 2 mmHg). Intravenous injection of the V1 antagonist, d(CH2)5Tyr(Me)AVP, significantly reduced the elevated mean arterial pressure induced by 50 or 100 ng/h of AVP (-7 +/- 4 and -11 +/- 2 mmHg, respectively). Plasma renin and norepinephrine concentrations were not affected by AVP infusion, while plasma epinephrine concentration was lower in the rats given 100 ng/h of AVP. Intravenous infusion of AVP did not alter bodyweight, serum electrolytes or osmolality. 4. These results suggest that AVP has a long-term pressor effect which is attributable to its vasoconstrictor action in conscious rats.

Animals↗
PubMedDate not supplied

Modulation of brain angiotensin-converting enzyme by dietary sodium and chronic intravenous and intracerebroventricular fusion of angiotensin II.

Angiotensin-converting enzyme (ACE) in rat brain closely resembled that in lung in its kinetics with the substrate Hip-His Leu, the inhibitors SQ 20,881 and SQ 14,225, and iun its Cl- activation profile. Modification of dietary NaCl intake was associated with marked changes in brain ACE activity. Sodium-loaded rats had lower activity of ACE in hypothalamus, striatum, and midbrain, and higher activity in spinal cord compared to controls. In sodium-restricted rats, ACE was elevated in pituitary and depressed in spinal cord. Chronic intravenous infusion of angiotensin (AII) was associated with a pattern of changes partly resembling sodium loading: ACE was depressed in hypothalamus and striatum but elevated in midbrain. After chronic intracerebroventricular infusion of AII, ACE was elevated in striatum and hippocampus, and depressed in spinal cord; a pattern of changes quite different from those associated with intravenous AII. These results show that ACE in several brain regions is sensitive to dietary sodium intake and support the hypothesis that angiotensin-containing neurons in these areas might be responsive to NaCl status of the animal. The observed changes in brain ACE do not seem to be explained in any simple manner by changes in circulating or central angiotensin II.

Angiotensin II↗