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Biomedical subjects

M Saitoh

Publications and source records attributed to M Saitoh.

At least 361 records · Page 20Linked to original sources
PubMed1987

Effects of myosin light-chain kinase inhibitor on catecholamine secretion from rat pheochromocytoma PC12h cells.

Release of dopamine from rat pheochromocytoma PC12h cells by high K+ (50 mM) was inhibited by a specific inhibitor of myosin light-chain kinase (ML-9) dose-dependently. The myosin light-chain kinase inhibitor also specifically inhibited the phosphorylation of a 20 KDa protein by myosin light-chain kinase. Myosin light chain kinase may play a stimulatory role in the release reaction of catecholamines from the rat pheochromocytoma cells.

Adrenal Gland Neoplasms↗
PubMed1987

Prostatic biopsy guided by transrectal ultrasonography using real-time linear scanner.

Prostatic needle biopsy guided by transrectal ultrasonography using a real-time linear scanner was performed on 257 cases in our outpatient clinic and mass screening program for prostatic diseases. The success rate was 99.2 per cent, and complications occurred in only 2 cases (0.8%) after biopsy. This newly developed method is recommended as being safer and more accurate than conventional ones.

Biopsy, Needle↗
PubMed1987

Estimation of catecholamine potencies on the myocardium by means of a new method.

A simple method is described for evaluating the potencies of catecholamines on the slow response of myocardium. Catecholamines depolarize guinea pig ventricular muscle cells exposed to the high K+ (27 mmol/l) Tyrode's solution containing 0.2 mmol/l Ba through an increase in slow channel conductance. Higher concentrations of catecholamines in addition induce spontaneous action potentials. This model was used to estimate and compare catecholamine potencies on myocardium. Catecholamine concentrations needed for depolarization alone or for depolarization plus automatic activity were taken as basis for comparison. The order of potency obtained by means of this new method was: l-isoproterenol greater than l-adrenaline greater than or equal to dl-noradrenaline greater than or equal to dobutamine greater than or equal to dopamine. This is similar to the order reported with other methods.

Action Potentials↗
PubMed1987

Effect of dietary alpha-linolenate/linoleate balance on brain lipid compositions and learning ability of rats.

Spontaneously hypertensive rats (SHR) and normotensive control, Wistar/Kyoto (WKY) rats through two generations were fed a semipurified diet supplemented either with safflower oil (rich in linoleate) or with perilla oil (rich in alpha-linolenate). The cerebral lipid contents and phospholipid compositions did not differ between the two dietary groups of SHR rats. There were also no differences in the unsaturated/saturated ratios of individual phospholipids or the proportions of plasma-logens. However, the proportions of (n-3) and (n-6) fatty acids were significantly different. Decreases in the proportions of docosahexaenoate [22:6 (n-3)] in phosphatidylethanolamine and phosphatidylserine in the safflower oil group were compensated for with increases in the proportions of docosatetraenoic [22:4 (n-6)] and docosapentaenoic [22:5 (n-6)] acids as compared with the perilla oil group. These differences in phospholipid acyl chains were much smaller than the difference in the proportions of linoleate and alpha-linolenate of the diets. In a brightness-discrimination learning test, the total number of responses to the positive and negative stimuli were less in the groups fed perilla oil. However, the alpha-linolenate-deficient group took longer to decrease the frequency of R- responses and therefore longer to learn the discrimination. Consequently, the correct response ratios were higher in the perilla oil groups than in the safflower oil groups. Thus, the dietary alpha-linolenate/linoleate balance influenced the (n-3)/(n-6) balance of polyenoic fatty acids differently among brain phospholipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Human placental glutathione transport mechanism].

The placental transport mechanism of glutathione (GSH) was investigated using microvillous membrane vesicles prepared from human term placenta. Using (3H-glycine)-labeled-GSH, it was clarified that GSH in the extravesicular compartment of placental microvillous membranes was rapidly degraded by gamma-GTP (gamma-glutamyltranspeptidase) and resulting amino acid, and 3H-labeled-glycine was actively transported via a sodium cotransport system. AT-125 treated microvillous membrane vesicles almost entirely lost its gamma-GTP activity, and showed intact GSH transport. Using AT-125 treated microvillous membrane vesicles, it was revealed that GSH was transported across the microvillous membrane as an anion via a membrane potential-dependent mechanism. These results indicated that gamma-GTP which existed in microvillous membrane played a role in GSH metabolism and that intracellular GSH was translocated out of the syncythiotrophoblast cell into the maternal blood space via a specific carrier in microvillous membrane because the GSH concentration was higher in intracellular than extracellular and extracellular membrane potential was positively charged.

Biological Transport, Active↗
PubMed1987

Cardiac involvement in a patient with limb-girdle muscular dystrophy.

A case of limb-girdle muscular dystrophy with cardiomegaly, electrocardiographic abnormalities, and paroxysmal ventricular tachycardia was described. Some of the interesting electrocardiographic features were discussed, and the importance of serial electrocardiograms for the detection of cardiac involvement is emphasized, since acute disturbances in cardiac rhythm may indicate that the patient is in immediate danger of sudden death.

Cardiomegaly↗
PubMed1987

[Nonenzymatic glucosylation of human placental trophoblast basement membrane collagen (relation to diabetic placenta pathology)].

Nonenzymatic glucosylation is a reaction in which glucose binds nonenzymatically to hemoglobin, serum protein and glomerular basement membrane collagen etc. It has been thought that nonenzymatic glucosylation results in functional and chemical changes in those substances (hemoglobin etc) and contributes to the pathological changes in diabetes mellitus. This time we investigated whether nonenzymatic glucosylation occurred in human placental trophoblast basement (TrBM) collagen or not. The ability of glucose to interact with TrBM collagen (nonenzymatic glucosylation of TrBM collagen) was examined by incubating TrBM collagen with 3H-D-glucose in vitro. As a result it was shown that nonenzymatic glucosylation occurred in TrBM collagen and nonenzymatic glucosylation of TrBM collagen depended on the glucose concentration, reaction time and reaction temperature. These results indicate that possibly hyperglycemia, via nonenzymatic glucosylation modifies the function and chemistry of TrBM collagen and is related to the placental pathological changes in diabetic pregnancy.

Adult↗
PubMed1986

The modulatory role of myosin light chain phosphorylation in human platelet activation.

Myosin 20 K-Da light chain phosphorylation in human platelets was found to be catalyzed by MLCK in the early phase during collagen activation. The effect of newly synthesized selective inhibitor of MLCK, ML-9, on collagen induced platelet activation was investigated. ML-9 delayed the time course of the myosin 20 K-Da light chain phosphorylation, sequentially led to a delay in aggregation, secretion and phosphorylation of the 40K-Da peptide, in a dose-dependent fashion. It is proposed that the MLCK catalyzed phosphorylation of myosin 20 K-Da light chain may be an initial response and if so may influence the sequent reactions in the activation of platelets with collagen.

Blood Platelets↗
PubMed1986

Protein kinase C negatively modulated by phorbol ester.

Pretreatment of protein kinase C with 12-O-tetradecanoylphorbol-13-acetate (TPA) and phospholipid resulted in complete inhibition of ATP/phosphotransferase activity, irreversibly. The inactivation by TPA required the phospholipid, and TPA alone did not cause inactivation. Ca2+ and diacylglycerol mimicked TPA. This action of TPA was not general for all protein kinases as it did not accelerate the inactivation of the catalytic subunit of cAMP-dependent protein kinase by phospholipid. The addition of MgATP to the reaction mixture completely protected protein kinase C from being inactivated by TPA, in the presence of phospholipid. The nucleotide-binding site of the enzyme was probably influenced by the binding of TPA and phospholipid.

Adenosine Triphosphate↗
PubMed1986

Ultrasound findings in urolithiasis in the lower ureter.

Thirty-two cases of urolithiasis in the lower ureter, difficult to detect by ordinary X-ray studies, were diagnosed accurately by ultrasound. Stonelike echoes were easily detected on the ultrasonograms when the ureter of the affected side was dilated. Patients should be examined by ultrasound prior to invasive retrograde pyelography.

Aged↗
PubMed1986

Comparison of digital examination and transrectal ultrasonography for the diagnosis of prostatic cancer.

The ability to detect prostatic cancer by transrectal ultrasonography was evaluated in a prospective blind study of 216 men. The sensitivity of transrectal ultrasonography was 86 per cent but the specificity was only 41 per cent. Tumors less than 1 cm. in diameter were most difficult to detect by transrectal ultrasonography. The positive and negative predictive values of transrectal ultrasonography were 36 and 89 per cent, respectively. Abnormal scans that strongly suggested carcinoma were present in 10 per cent of the men who had a normal digital examination but no biopsy was performed. Transrectal ultrasound is a sensitive method to detect all but small prostatic tumors and it can detect tumors that are not evident by digital examination. To date, however, transrectal ultrasonography may be difficult to use for routine screening in the United States because of the low positive predictive value. Nevertheless, further investigation of this technique is warranted to define its role in improving the diagnosis of prostatic cancer.

Humans↗
PubMed1986

Serological surveys of Corynebacterium kutscheri infection in mice and rats.

Serological surveys of mice and rats naturally infected with Corynebacterium kutscheri were performed by examining serum samples collected from breeder and laboratory colonies between 1981 and 1983. Among 756 mice from 73 conventional colonies, only 4 animals (0.5%) from 3 colonies (4.1%) developed C. kutscheri antibody of 1:40 to 1:2, 560 titers. Three of them suffered from abscess caused by the organism. Regarding a titer of 1:40 or higher as reliably positive, 87 (13.0%) of 669 conventional rats or 20 (32.8%) of 61 colonies were found to be infected with the organism. The antibodies were detected in both types of animals older than 6 months of age. No lesions caused by C. kutscheri were found in almost all the rats examined. Germ-free and SPF mice and rats were all negative for antibody at 1:5 serum dilution.

Animals↗
PubMed1986

Evaluation of effect of treatment for primary lesions of stage D2 prostatic cancer by means of transrectal ultrasonotomography.

The effect of treatment for primary prostatic lesions of Stage D2 prostatic cancer was evaluated by means of transrectal ultrasonotomography and was compared with that for distant metastatic lesions. A new score system was introduced to assess the effect of treatment for the primary lesions of prostatic cancer from the ultrasonic findings of the prostate on a single examination after treatment. In 19 subjects evaluated as effective or moderate in the treatment of primary lesions, 9 were also evaluated as effective or moderate in the treatment of metastatic lesions, while 10 were judged as poor in the treatment of metastatic lesions. In 12 subjects which were evaluated as poor in the treatment of primary lesions, 3 were judged as moderate in the effect of treatment of metastatic lesions, while 9 were judged as poor. It was proved that the correct evaluation of the primary prostatic tumor was required to perform adequate treatment for Stage D2 prostatic cancer.

Combined Modality Therapy↗
PubMed1986

Naphthalenesulfonamides as calmodulin antagonists and protein kinase inhibitors.

N-(6-Aminoethyl)-5-chloro-1-naphthalenesulfonamide (A-3), which is a shorter alkyl chain derivative of the calmodulin (CaM) antagonist, W-7, was found to inhibit smooth muscle myosin light chain kinase (MLC-kinase) through a mechanism different from that related to W-7. Both the holoenzyme and the catalytic fragment, which is active without CaM, were susceptible to A-3 with a similar concentration dependency, thereby indicating that the inhibitory effect is due to the direct interaction of the compound with the enzyme molecule and not with the enzyme activator. Naphthalenesulfonamides are both CaM antagonists and direct inhibitors of MLC-kinase, and these actions depend on the length of the alkyl chain (C2-C6). Although the potencies in inhibiting CaM functions increased, the direct effects on MLC-kinase decreased with extension of the carbon chain of the derivatives. Kinetic studies indicated that A-3 inhibited MLC-kinase competitively with respect to ATP and that the Ki value was 7.4 microM. A-3 was also a competitive inhibitor of cAMP-dependent protein kinase, cGMP-dependent protein kinase, protein kinase C, casein kinase I, and casein kinase II, with respect to ATP. The Ki values of naphthalenesulfonamides for these enzymes also increased with extension of the carbon chain of the derivatives. These results suggest that naphthalenesulfonamides inhibit protein phosphorylation not only by inhibition of the enzyme-activating process but also by inhibition of the catalytic process. The mode of interaction between the derivatives and protein kinases differs from the interaction between the derivatives and CaM.

Adenosine Triphosphatases↗