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Biomedical subjects

J Nishimura

Publications and source records attributed to J Nishimura.

At least 325 records · Page 18Linked to original sources
PubMed1986

Binding of [3H]prazosin to porcine aortic membranes: interaction of calcium antagonists with vascular alpha-1 adrenoceptors.

The characteristics of [3H]prazosin binding and the interaction of Ca antagonists with alpha-1 adrenoceptors in the porcine aortic membranes were investigated. The binding characteristics of [3H]prazosin, namely, the kinetics and affinity of binding, saturability, competition by adrenergic agonists and antagonists, stereoselectivity and the localization of binding sites, indicated that [3H]prazosin binds specifically to the alpha-1 adrenoceptors in the sarcolemma of porcine aortic smooth muscle cells. In the inhibition study by several Ca antagonists, the specific binding of [3H]prazosin to aortic membranes was inhibited by verapamil (Ki = 0.66 microM), D600 (Ki = 0.86 microM), nicardipine (Ki = 2.3 microM) and d-cis diltiazem (Ki = 9.8 microM). Nifedipine and nitrendipine, potent dihydropyridine Ca antagonists, only partially inhibited the [3H]prazosin binding, up to 10(-4) M. l-Cis and dl-trans diltiazem, the less potent stereoisomers as Ca channel blockers compared with the d-cis form, showed a similar and greater potency as a competitor to alpha-1 adrenoceptors, respectively. These observations indicate that verapamil, D600, nicardipine and diltiazem interact with vascular alpha-1 adrenoceptors and that the potency of these compounds as a competitor to alpha-1 adrenoceptors does not parallel their potency as Ca channel blockers.

Animals↗
PubMed1986

Binding of [3H]-nitrendipine and [3H]-diltiazem to rat myocardial sarcolemma.

The binding properties of two major and chemically distinct calcium antagonists, [3H]-nitrendipine and [3H]-diltiazem, were investigated in highly purified rat cardiac sarcolemma. In the case of [3H]-nitrendipine, there appeared a single set of high affinity binding sites with a B max of approximately 0.9 pmol X mg-1 protein and a KD of approximately 0.15 nmol/l. Because of the extremely high value obtained for KD (29 mumol/l), the specificity of [3H]-diltiazem binding seemed questionable. The specific binding of 0.1 nmol/l [3H]-nitrendipine to cardiac sarcolemma was inhibited by nitrendipine and nifedipine (1 mumol/l), only partly inhibited by verapamil (1 mumol/l), and was enhanced by diltiazem (0.1-10 mumol/l). The stimulation of [3H]-nitrendipine binding by diltiazem was associated with an increase in the number of binding sites, Bmax, but with no change in the KD or the Hill coefficient. An enantiomer of diltiazem (1-cis) neither stimulated nor inhibited the [3H]-nitrendipine binding. These results strongly suggest that major prototype calcium antagonists have distinct and variously interacting sites of action in the rat cardiac sarcolemma.

Animals↗
PubMed1986

Different susceptibility of various T-dependent immune reactions after in vivo administration of cyclosporin A in mice.

The suppressive effects of Cyclosporin A (Cs A) on various types of T-dependent immune reactions, including delayed footpad reaction (DFR), plaque-forming cells (PFC), and cell-mediated cytolysis (CMC), were compared after intramuscular (i.m.) administration of this drug into mice immunized intraperitoneally (i.p.) with chicken erythrocytes (CRBC). A single injection with a high dosage of 500 mg/kg, at the time of the antigen administration suppressed only the PFC, but not the DFR and CMC. Three low dosage injections of 50 mg/kg the day before, on, and after the immunization also induced suppression of PFC. In this treatment, a dose of 100 mg/kg had a marked affect on PFC and CMC. DFR was slightly suppressed with a dose of 100 mg/kg, but markedly so with a dose of 200 mg/kg. This indicates that PFC is very sensitive to Cs A, CMC is moderately sensitive, and DFR is relatively resistant. The injections of Cs A close to the time of antigen administration are more effective than before or after. Thus it is indicated that the 3 types of reactions differ in their susceptibility to Cs A. It might be speculated that the susceptibility to Cs A varies among the types of T cells responsible for these 3 immune reactions, although this is only one of several possibilities.

Animals↗
PubMed1986

[Clinical investigation of the therapeutic effects of cefmenoxime in the treatment of infections complicated by hematological diseases].

Therapeutic effects on cefmenoxime hemihydrochloride (CMX, Bestcall), a new synthetic cephem antibiotic, were examined in the treatment of various infections complicated with hematological diseases. The number of patients treated with CMX was 37 including 5 cases of sepsis or suspected sepsis, 14 cases of pneumonia or suspected pneumonia, 5 cases of upper respiratory diseases, 2 cases of urinary tract infections and 11 cases of other infections. All of these infections were complicated with hematological diseases: Acute leukemia, 13 cases; chronic myelocytic leukemia, 1 case; adult T cell leukemia, 3 cases; malignant lymphoma, 8 cases; Hodgkin's disease, 2 cases and myeloma, 3 cases. CMX were administered by a single intravenous injection or by a drip infusion. The dose was between 2 and 6 grams per day. Good to excellent clinical results were obtained in 25 out of 37 cases, total effective rate of 67.6%. No clinical side effects or abnormal laboratory findings attributable to CMX were observed except for light diarrhea in 2 cases. By the clinical investigation, it was demonstrated that CMX was one of safe and effective antibiotics for treating infections in the compromised hosts complicated with hematological diseases.

Acute Disease↗
PubMed1985

Specific binding of [3H] mepyramine to histamine H1-receptors in the sarcolemma from porcine aorta and coronary artery.

We studied the subcellular distribution and the properties of [3H] mepyramine binding in the porcine vascular smooth muscle. A close correlation was observed between the specific binding activity of [3H] mepyramine and the extent of the enrichment of sarcolemmal marker enzyme in 4 subfractions obtained by sucrose density gradient centrifugation of the aortic microsome. In the binding isotherm in the sarcolemmal fractions from the aorta and coronary artery, there was no difference in the Kd value, but the Bmax of the coronary artery was significantly lower than that of the aorta. Thus, there is a single type of high affinity mepyramine binding site in the porcine vascular smooth muscle sarcolemma and the number of H1-receptors of the coronary artery may be smaller than that of the aorta.

Aminopyridines↗
PubMed1985

Effect of platelet-derived growth factor and bone marrow-conditioned medium on the proliferation of human bone marrow-derived fibroblastoid colony-forming cells.

The effects of various human sera, platelet lysates and platelet-derived growth factor (PDGF) on the proliferation of human bone marrow-derived fibroblastoid colony-forming cells (CFU-F) were examined. We obtained nearly identical growth curves of fibroblastoid colonies with sera, platelet lysates and PDGF as stimulants and concluded that PDGF was a main growth factor for CFU-F in human serum. In contrast to colony size, CFU-F number was irrelevant to the concentration of PDGF. Removal of culture medium containing hemopoietic cells after short-term incubation of bone marrow cells reduced both colony number and size in CFU-F cultures. When each of bone marrow-conditioned medium (BMCM), peripheral blood mononuclear cells (MNC) and phytohemagglutinin-stimulated leukocyte-conditioned medium (PHA-LCM) was added to the cultures, CFU-F number and colony size recovered. The role of PDGF and the factors present in BMCM, MNC and PHA-LCM in the growth of CFU-F and their precursor cells were discussed.

Bone Marrow↗
PubMed1984

Protamine inhibits platelet derived growth factor receptor activity but not epidermal growth factor activity.

Protamine sulfate blocked 125I-PDGF binding to its specific physiological receptor on Swiss mouse 3T3 cells. Reduced 125I-PDGF binding in the presence of protamine sulfate correlated directly with a protamine sulfate dose-dependent decrease in the PDGF-dependent incorporation of [3H]-thymidine into 3T3 cells and a decreased PDGF-stimulated tyrosine-specific protein kinase activity in isolated membrane preparations of 3T3 cells. Protamine sulfate blocked 125I-PDGF binding to simian sarcoma virus transformed cells (SSV-NIH 3T3 and SSV-NP1 cells) and to nontransformed cells in a manner qualitatively identical to unlabelled PDGF. In contrast, protamine sulfate enhanced the specific binding of 125I-EGF by increasing the apparent number of EGF receptors on the cell surface. The increase in 125I-EGF receptor binding was not prevented by cycloheximide nor by actinomycin D. Protamine sulfate did not affect 125I-EGF binding to membranes from 3T3 cells or the EGF-stimulated 3T3 cell membrane tyrosine specific protein kinase activity, suggesting that protamine sulfate may have exposed a population of cryptic EGF receptors otherwise not accessible. Protamine sulfate was fractionated into four active fractions by Sephadex G-50 gel filtration columns; the half maximum inhibition concentration of 125I-PDGF binding to 3T3 cells of protamines I and II (MW approximately 11,000 daltons and 7,000 daltons, respectively) is approximately 0.4 microM. Protamine II (MW approximately 4,800 daltons) was equally active (half maximum inhibition concentration approximately 0.4 microM); protamine IV (MW approximately 3,300 daltons) was substantially less active (half maximum inhibition concentration approximately 2.8 microM). These investigations have extended previous observations that protamine sulfate is a potent inhibitor of PDGF binding and establish that protamine sulfate blocks PDGF binding at the physiological receptor, preventing PDGF initiated biological activities. Protamine sulfate can be used as a reagent to separate the influence of PDGF and EGF on cells with high specificity and has been used to demonstrate that the receptors on simian sarcoma virus transformed 3T3 cells qualitatively respond identically to protamine sulfate as to unlabelled PDGF and are likely identical to those on nontransformed 3T3 cells.

Animals↗
PubMed1983

Platelet-derived growth factor stimulates the phosphorylation of ribosomal protein S6.

The human platelet derived-growth factor (PDGF) is both a potent mitogen and a strong chemoattractant protein for cells involved in inflammation and repair. In seeking mechanisms by which PDGF might initiate specific activities in target cells, it was found that highly purified PDGF stimulates the phosphorylation of an Mr approximately 33000 protein in confluent Swiss mouse 3T3 cells [Biochem. Biophys. Res. Commun. (1981) 103, 355-361]. The Mr approximately 33000 protein has now been recovered in polysomes by differential centrifugation and identified as ribosomal protein S6 by two-dimensional polyacrylamide gel electrophoresis.

Animals↗
PubMed1982

Platelet-derived growth factor stimulates tyrosine-specific protein kinase activity in Swiss mouse 3T3 cell membranes.

Platelet-derived growth factor (PDGF) stimulates the incorporation of 32P from [gamma-32P]ATP into a Mr approximately 170,000 protein by an endogenous tyrosine-specific protein kinase in membrane preparations of Swiss mouse 3T3 cells. Epidermal growth factor (EGF), but not fibroblast growth factor (FGF) or insulin, stimulates limited incorporation of 32P into a protein of similar molecular weight. The ligand concentration required for half-maximal activity (S0.5) for PDGF stimulation of phosphorylation is 50 ng/ml; saturation is achieved at 300 ng/ml. The S0.5 for ATP is 15 microM. Mg2+ or Mn2+ is required for protein kinase activity. Stimulation of PDGF results in the preferential phosphorylation of tyrosine residues in this Mr approximately 170,000 membrane protein. The Mr approximately 170,000 protein can be resolved into Mr approximately 180,000 and 160,000 components in 4% NaDodSO4 gels. PDGF stimulates 32P incorporation preferentially into the Mr approximately 180,000 and less extensively into the Mr approximately 160,000 protein. EGF stimulates 32P incorporation predominantly into a protein of Mr approximately 160,000. The similarity of PDGF and EGF in stimulating phosphotyrosine-specific protein kinase activity and the stimulation of a similar activity by viral transformation (src) genes suggest that a common mechanism may exist for the phenotypic expression of increased DNA synthesis and cell growth stimulated by these separate factors.

Animals↗
PubMed1982

Calcitonin in plasma and cerebrospinal fluid from normal subjects and patients with medullary thyroid carcinoma: possible restriction of calcitonin by the blood-brain barrier.

Calcitonin (CT) was measured by RIA in samples of plasma and cerebrospinal fluid (CSF) obtained simultaneously from 27 normal volunteers and 8 patients with medullary thyroid carcinoma to examine the extent of penetration of CT across the blood-brain barrier. CT concentrations in plasma and CSF were 68.2 +/- 25.1 pg/ml (mean +/- SD; range, less than 25-110) and 38.5 +/- 12.1 pg/ml (range, less than 25-56), respectively, in normal subjects and 5,650 +/- 4,120 pg/ml (range, 980-21,100) and 36.1 +/- 11.1 pg/ml (range, less than 25-45), respectively, in patients with medullary thyroid carcinoma. No significant difference was observed in the mean concentrations of CT in CSF from normal subjects and that from patients with medullary thyroid carcinoma. The concentration of CT in CSF from patients with medullary thyroid carcinoma was only 0.05-2.5% the concentration of CT in plasma. Moreover, there was no significant correlation between the concentrations of CT in plasma and CSF from normal subjects, from patients with medullary thyroid carcinoma, or when normal and patient groups were combined. It is concluded that penetration of CT from blood in CSF is minimal.

Adolescent↗