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Biomedical subjects

S Hashimoto

Publications and source records attributed to S Hashimoto.

At least 1,261 records · Page 70Linked to original sources
PubMed1984

Computed tomography of sinonasal non-Hodgkin lymphoma.

Seven cases of primary malignant lymphoma of the nasal cavity and paranasal sinuses were examined with computed tomography. Histology was "diffuse non-Hodgkin lymphoma" in all cases. Computed tomography clearly delineated the extent of the tumors, which involved either the maxillary sinus or the nasal cavity and extended into the subcutaneous tissue of the cheek, as well as in the infratemporal fossa or nasopharynx. Bony wall destruction was evident in only three cases; it was slight and clearly less marked than the destruction usually encountered in cases of carcinoma.

Female↗
PubMed1983

Activity of acyl-CoA: cholesterol acyltransferase and 3-hydroxy-3-methylglutaryl-CoA reductase in subfractions of hepatic microsomes enriched with cholesterol.

The influence of membrane cholesterol on the activities of acyl-CoA: cholesterol acyltransferase and 3-hydroxy-3-methylglutaryl-CoA reductase was examined in three microsomal subfractions (RNA-rich, RNA-poor, and smooth) that had been enriched with cholesterol by incubation with mixed lipoproteins from hypercholesterolemic rabbit serum. Acyl-CoA: cholesterol acyltransferase activity was significantly stimulated in the three subfractions, particularly in the RNA-rich microsomal component. 3-Hydroxy-3-methylglutaryl-CoA reductase, on the other hand, was suppressed (30%) in only one (RNA-poor) of the three microsomal subfractions, despite a 1.4-fold increase in the concentration of membrane cholesterol. An attempt was made to distinguish between an effect based exclusively on an increase in available cholesterol substrate and an activation of acyl-CoA: cholesterol acyltransferase in RNA-rich microsomes enriched with cholesterol. An experimental design was devised so that substrate cholesterol was provided in the form of heated smooth microsomes and acyl-CoA: cholesterol acyltransferase was provided as a separate preparation in the form of RNA-rich microsomes. Appropriate controls were carried out to test for transfer of cholesteryl ester between the two sets of particles. The results suggested that cholesterol enhanced acyl-CoA: cholesterol acyltransferase activity by serving both as a substrate and as a non-substrate modulator.

Acyltransferases↗
PubMed1983

[Acute antihypertensive effect of captopril in hypertensive patients: with special reference to kallikrein-kinin system].

In order to clarify the role of the kallikrein-kinin system in the hypotensive mechanisms of converting-enzyme inhibition, captopril was administered in a single oral dose of 50 mg to 17 hypertensive patients, of whom 14 had essential hypertension, one had chronic renal failure, one had primary aldosteronism, and one had glucocorticoid responsive hyperaldosteronism. Captopril lowered blood pressure remarkably in either low-renin or normal-, and high-renin hypertensives, however, there was no significant relationship between the fall in blood pressure and pretreatment levels of plasma renin activity (PRA) in any of the patients any time after the administration. PRA was significantly increased in normal- and high-renin hypertensives but not in low-renin patients. Plasma aldosterone concentration (PAC) was decreased significantly in normal- and high-renin patients, while no significant change in PAC was observed in patients with low-renin activity. Captopril elevated plasma bradykinin concentration (PBK) from a control value of 12.5 +/- 4.1 (mean +/- s.d.) to 20.3 +/- 7.7 pg/ml (p less than 0.001) at 30 min, and there was a significant correlation between changes in PBK and changes in mean blood pressure 120 min after the administration in all the patients (r = 0.741, p less than 0.01, n = 17). In one patient with primary aldosteronism, PBK increased from a baseline of 10.0 to a maximum value of 19.0 pg/ml, corresponding to the rapid fall in blood pressure. Also, in one patient with glucocorticoid responsive hyperaldosteronism, captopril increased PBK from a control of 14.1 to 27.9 pg/ml at 30 min, corresponding to the marked fall in blood pressure from 170/106 to 136/90 mmHg. From these findings, it is suggested that the accumulation of kinins following captopril administration plays a major role in the short-term reduction of blood pressure in hypertensive patients, especially in those with low renin-angiotensin activity.

Adult↗
PubMed1983

[Relation between dopamine secretion and saltsensitivity in essential hypertension].

The study was designed to explore the mechanism of dopamine secretion related to blood pressure in patients with essential hypertension. The 19 patients with essential hypertension were administered to first 153 mEq of sodium and 70 mEq of potassium diet, next 51 mEq of sodium and finally 340 mEq of sodium for every one week. The patients whose mean blood pressure elevated 10 mmHg or more on the high-sodium loading and depleted 10 mmHg or more on the low-sodium loading were classified as A-, and depleted 10 mmHg or more on the high-sodium loading and elevated 10 mmHg or more on the low-sodium loading as B- and the other patients as C-group. The hypertensive patients were also classified to low- (below 1.0 ng/ml/h), normal- (from 1.0 to 6.0 ng/ml/h) and high- (above 6.0 ng/ml/h) renin groups from the results of plasma renin activity (PRA) obtained after an intravenous injection of furosemide (1 mg/kg) followed by 2-hour ambulation. PRA, plasma aldosterone concentration (PAC), plasma epinephrine concentration (PE), plasma norepinephrine concentration (PNE), plasma dopamine concentration (PDC), circulating plasma volume, body weight, hematocrit and pulse rate were measured at 8 a.m. after sodium loading for 8-days. The patients with essential hypertension were classified into 6 of A- and 2 of B- and 11 of C-groups with the maneuver of sodium loading. The A-group contained 5 patients with low-renin. The circulating plasma volume was relatively large (44.7 +/- 4.8 ml/kg) and markedly increased on the high-sodium loading in 6 patients of A-group. The increment of body weight was higher in A-group than the other groups on the high-sodium loading. In the 2 patients of B-group, hematocrit and pulse rate increased on the low-sodium and decreased on the high-sodium loading, and the variability were larger than the other groups. In the A-group, PRA was significantly low (0.5 +/- 0.4 ng/ml/h) and increased on the low-sodium loading and decreased on the high-sodium loading, and the variability of PRA was lesser than the other groups. In the A-group, PAC was within normal range (5.4 +/- 2.8 ng/dl) and the variation of PAC paralleled with the change of PRA, but the variability of PAC was remarkably low. PE and PNE were unchanged in the A- and the C-groups, but the significant high values were observed in the B-group on the high-sodium loading.

Adult↗
PubMed1983

Distinct heme-substrate interactions of lactoperoxidase probed by resonance Raman spectroscopy: difference between animal and plant peroxidases.

Resonance Raman scattering from cow milk lactoperoxidase (LPO) and its complexes with various electron donors and inhibitors was investigated. The Raman spectrum of LPO is strikingly close to that of hog intestinal peroxidase but distinctly dissimilar to that of horseradish peroxidase (HRP). The v10 frequency suggested the six-coordinate high-spin structure of heme for native LPO in contrast with the five-coordinate high-spin structure for HRP. For the v10 band, benzohydroxamic acid caused a frequency shift with HRP but not with LPO. Guaiacol, o-toluidine, and histidine brought about a frequency shift of the v4 mode for LPO but not for HRP. The frequency shift was restored upon removal of the substrate or inhibitor by dialysis. The down shift of the v4 frequency is considered to represent an appreciable donation of electrons from the substrate or inhibitor to the porphyrin LUMO and thus their direct interaction with the heme group. From the relative intensity of the shifted and unshifted v4 lines, the dissociation constant was determined to be Kd = 52 mM for guaiacol and Kd = 87 mM for histidine at pH 7.4. The binding of histidine was relatively retarded in the presence of sulfate anion (Kd = 150 mM for 0.53 M sulfate present), and imidazole alone yielded no frequency shift, indicating the binding of the carboxyl group of histidine to the protein cationic site on one hand and a weak charge-transfer interaction between the imidazole group and the heme group on the other.

Animals↗
PubMed1983

Nerve growth factor-induced decrease in the cell-free phosphorylation of a soluble protein in PC12 cells.

Incubation of cell-free extracts from PC12 cells with [32P]ATP leads to the phosphorylation of a 100,000-dalton protein. In extracts from cells treated with nerve growth factor, the labeling of the 100,000-dalton protein is substantially and selectively reduced. Direct quantitation indicates that the reduction is a minimum of 30-50% in the various experiments. The decrease is evident after as little as 15 min of nerve growth factor treatment, and disappears within 2 h after the removal of nerve growth factor. The decrease is dose dependent; a complete response is seen after treatment with 10 ng of nerve growth factor/ml. Some decrease in phosphorylation is also seen after treatment of the cells with epidermal growth factor, 12-O-tetradecanoylphorbol-13-acetate, or 5'-N-ethylcarboxamideadenosine, a potent adenosine receptor agonist, but not after treatment with insulin. The phosphorylation of the 100,000-dalton protein, in extracts from either control or nerve growth factor-treated cells, leads almost exclusively to the formation of phosphothreonine. The addition of equal amounts of extract from untreated cells and extract from nerve growth factor-treated cells produces a level of phosphorylation exactly intermediate between those of the two extracts used separately, indicating the absence of a soluble kinase inhibitor. The data suggest that nerve growth factor treatment produces either a covalent inhibition or a physical removal of the kinase for the 100,000-dalton protein.

Adenosine↗
PubMed1983

Transcriptional regulation of the tryptophan oxygenase gene in rat liver by glucocorticoids.

The enzyme tryptophan oxygenase (EC 1.13.11.11), which is synthesized in rat liver, is induced by glucocorticoids. We have used cloned tryptophan oxygenase genomic and cDNA sequences to study the mechanism of induction. Rat liver poly(A+) RNA was separated on a formaldehyde gel, blotted to nitrocellulose, and hybridized to a nick-translated tryptophan oxygenase cDNA clone to analyze the kinetics of tryptophan oxygenase mRNA accumulation. Transcription in isolated rat liver nuclei was investigated to determine the relative rate of transcription of the tryptophan oxygenase gene. Analysis of the accumulation of albumin mRNA, which is unaffected by glucocorticoids, served as an internal control. We show here that the synthetic glucocorticoid dexamethasone causes a 10-fold increase in the concentration of tryptophan oxygenase mRNA sequences in rat liver, and that this is a consequence of transcriptional activation of the tryptophan oxygenase gene.

Animals↗
PubMed1983

Functional pool of cyclic adenosine 3',5'-monophosphate in rabbit platelets.

Accumulation of the newly formed 14C-cyclic adenosine 3',5'-monophosphate (cyclic AMP) was found in the P1 (1.0) fraction, i.e. a platelet plasma membrane fraction which was obtained from 14C-adenine-labeled platelets. On the other hand, total cyclic AMP as determined simultaneously was located mainly in the platelet soluble fraction. Furthermore, the highest value of the cyclic AMP-binding capacity was found in the P1 (1.0) fraction. The cyclic AMP-binding activity of platelet membranes was attributed to two proteins with molecular weights of approximately 48,000 and 68,000. The treatment of 14C-adenine-prelabeled platelets with thrombin (1 unit per ml) led to about 40% decrease in the newly formed 14C-cyclic AMP level and 18% reduction of 14C-adenosine triphosphate level in whole platelets within 10 sec. On the other hand, the 14C-cyclic AMP level in the P1 fraction decreased by about 80% of the control value while the total cyclic AMP in this fraction was almost unchanged. This rapid and striking fall in the membrane 14C-cyclic AMP level could be correlated with the more than 2fold stimulation of the membrane-bound cyclic AMP phosphodiesterase, together with the more than 20% inhibition of both the cyclic AMP-binding capacity and the adenyl cyclase in platelet membranes by thrombin treatment. These observations suggest the possibility that functional pool of cyclic AMP related to thrombin-induced aggregation is located in rabbit platelet plasma membrane.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Protein C inhibitor. Purification from human plasma and characterization.

Protein C inhibitor was isolated from human plasma using conventional chromatographic technique consisting of barium citrate adsorption, polyethylene glycol fractionation, DEAE-Sepharose CL-6B treatment, ammonium sulfate fractionation, dextran sulfate-agarose chromatography, gel filtration on ACA-44, and DEAE-Sephacel chromatography. The purified protein C inhibitor is a single polypeptide chain with an apparent Mr = 57,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The inhibitor is heterogeneous in pI: six pIs exist between pH 7.4 and 8.6. The inhibitor was shown to be different from the already known plasma protease inhibitors by chemical and immunological analyses. It migrates to the late alpha 1-globulin region on agarose gel electrophoresis. The inhibitor reduced the amidolytic activity of activated protein C noncompetitively by forming a 1:1 molar complex with the enzyme, determined by the use of a fluorogenic substrate toward activated protein C (Boc-Leu-Ser-Thr-Arg-4-methylcoumaryl-7-amide). The inhibition constant (Ki) of the inhibitor against activated protein C was 5.8 x 10(-8) M. The inhibitor also blocked the prolongation of activated partial thromboplastin time by activated protein C. The immunoglobulin which was produced by the inhibitor completely removed the inhibitory activity present in normal human plasma against activated protein C. This suggests that the inhibitor which we have isolated is the only inhibitor in plasma against activated protein C.

Amino Acids↗
PubMed1983

Regulation of activated protein C by thrombin-modified protein S.

Protein S, a vitamin K-dependent plasma protein having Gla-residues, increases the rate of inactivation of Factor Va by activated protein C by enhancing the binding of activated protein C to phospholipid [Walker, J.F. (1981) J. Biol. Chem. 256, 11128-11131]. The present study aimed at elucidating the effect of thrombin-modified protein S on Factor Va inactivation by activated protein C. Nondigested protein S consisted 81% of intact form and 19% of modified form, and thrombin-digested protein S had 96% modified form. Protein S, both nondigested and digested, did not show any effects on the amidolytic activity of activated protein C towards synthetic peptide substrate. Nondigested protein S stimulated the Factor Va inactivation by activated protein C, whereas the digested protein appeared to suppress the inactivation. Protein-phospholipid binding experiments showed that although nondigested protein S enhanced the binding of activated protein C to phospholipid stoichiometrically, digested protein S appeared to not only suppress the complex formation, but also dissociate the complex. This evidence suggested that protein S modified by thrombin regulates the action of activated protein C towards Factor Va on phospholipid.

Enzyme Activation↗
PubMed1983

Monocyte-mediated suppression of mitogen responses of lymphocytes in uremic patients.

In the present experiment, we investigated the mechanism of the suppressed mitogen responses of peripheral blood mononuclear cells (PBMC) from uremic patients. We used phytohemagglutinin (PHA) and concanavalin A (Con A) as T cell mitogens, pokeweed mitogen (PWM) as a T cell-dependent B cell mitogen, and Staphylococcus aureus Cowan I (STA) as a T cell-independent B cell mitogen. PBMC from uremic patients showed significantly suppressed responses to PHA (p less than 0.05), Con A (p less than 0.05) and STA (p less tha 0.01) compared with those from healthy controls, but there was no significant difference in PWM response. However, these suppressed responses to PHA and Con A were markedly restored by depletion of phagocytic cells from PBMC. Although STA responses were also restored markedly in uremic patients, some patients still showed lower responsiveness to STA indicating the possibility of functional B cell defects. To further clarify the mechanism of the suppressed responses to mitogens, PBMC or nonphagocytic cells from uremic patients were cocultured with control T cells in the presence of PHA, or the effects of adherent cells from uremic patients on PHA responses of autologous or allogeneic control T cells were studied. From these experiments, it was suggested that the suppressed responses of PBMC to mitogens in uremia were mediated by monocytes.

Adult↗
PubMed1983

Arterial renin--partial characterization and its possible role in the pathogenesis of hypertension.

1) Renin-like enzyme of rat aorta was purified by chromatography with DEAE-cellulose and Sephadex G-200. 2) The molecular weight of renin-like enzyme was 124,000 and 72,000 on Sephadex G-200 gel filtration. The isozymes, however, migrated as a single band with molecular weight of 71,000 on SDS/polyacrylamide gel electrophoresis. These isozymes showed the same optimal pH (6.5) and temperature (37 degrees C). 3) Renin-like enzyme showed high activity in the microsomal fraction of the aorta. 4) In one-clip, two-kidney Goldblatt hypertensive rats, the aortic renin concentration increased significantly, but not parallel with the activity in plasma. 5) Renin, widely distributed in subcellular fractions of the aorta, may play a possible role in the local control of vascular tone. It is likely that renin in vascular wall is of local origin.

Animals↗