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Biomedical subjects

Y Hashimoto

Publications and source records attributed to Y Hashimoto.

At least 973 records · Page 54Linked to original sources
PubMed1992

Left ventricular geometry in Takayasu arteritis complicated by severe aortic regurgitation.

Although it has been reported that the aortic regurgitation (AR) of patients with Takayasu arteritis is due to dilatation of the aortic ring, the geometry of the left ventricle (LV) has not been described. We compared the cardiac findings in patients with Takayasu arteritis (TA) and severe AR with those of patients having severe AR of other origins. Echocardiographically, wall thickness (WT) and the concentric hypertrophic ratio (WT/WT + left ventricular end-diastolic dimension) were greater in patients with TA. It is concluded that the LV of the TA patients revealed concentric hypertrophy even when AR was severe.

Aortic Valve Insufficiency↗
PubMed1992

Monoclonal autoantibodies to cardiolipin derived from SLE mice.

The objective of this study was to clarify the specificity of anticardiolipin antibodies (aCL). Eighteen monoclonal hybridoma aCL from systemic lupus erythematosus (SLE)-prone MRL/Mp-lpr/lpr mice were established, and the reactivity of monoclonal aCL to phospholipids, DNA, nuclei of human epithelial cells, platelets, vascular endothelial cells, heparin, protein C and thrombomodulin was examined. All the 18 monoclonal aCL reacted with phosphatidylserine and some showed reactivity to phosphatidylinositol and phosphatidylcholine. Six of 16 monoclonal aCL were demonstrated to have the property of lupus anticoagulant. Monoclonal aCL were classified into three categories, in terms of DNA-binding specificity. Ten of 18 aCL had characteristics of antinuclear antibodies. Six of 11 aCL reacted with platelets. Three of 18 aCL were bound to vascular endothelial cells and to heparin. No monoclonal aCL reacted with protein C or thrombomodulin. Therefore, the conclusion was made that monoclonal aCL from SLE mice showed a polyspecific nature.

Animals↗
PubMed1992

Correlation of axenic linkage groups with the position of the microtubule-organizing center in aggregating Dictyostelium.

Positioning of the microtubule-organizing center (MTOC) in Dictyostelium discoideum was found to be genetically regulated. We examined the wild-type strain NC-4 cells independently maintained in different laboratories, freshly recovered cells from spores stocked for over 20 years, the temperature-sensitive growth mutant HU49 isolated from NC-4, as well as strain V-12 which is the opposite mating-type to NC-4. During aggregation on nonnutrient agar plates, all these strains showed similar cell polarity, as defined by the alignment of the nucleus ahead of the MTOC. By contrast, in Ax2 and Ax3, axenic strains carrying axenic mutations on linkage groups II and III, the MTOC was usually positioned ahead of the nucleus. Cells containing axenic linkage group II but not III positioned the MTOC ahead of the nucleus. Conversely cell polarity of strains including axenic linkage group III but not II was similar to that of wild-type cells. Thus axenic linkage group II, probably axeC or other linked gene(s) not yet identified, is responsible for the location of the MTOC anterior to the nucleus during aggregation. The anterior positioning of the MTOCs was prevented by growth on bacteria in cells carrying both axenic linkage groups, but not in those carrying only axenic linkage group II.

Animals↗
PubMed1992

An enzyme immunoassay for cell proliferation using monoclonal antibodies directed against a cell proliferation-associated antigen.

An enzyme immunoassay (EIA) for assessment of cell activation and proliferation was developed by the use of monoclonal antibodies (MoAb) directed against a ubiquitous growth-associated antigen, gp125. Test cells distributed in a microtest plate were labeled with anti-rat gp125 MoAb, B3, for rat cells or anti-human gp125 MoAb, HBJ127, for human cells and subsequently with rabbit anti-mouse immunoglobulins. The cell-bound antibody was assessed by a colorimetric enzyme assay using horse-radish peroxidase-modified protein A and 2,2'-azinobis(3-ethylbenzthiazoline sulfonic acid). To terminate the reaction and to make the reaction mixture transparent, sodium dodecyl sulfate (SDS) was added to the mixture. The intensity of the developed color was measured by use of a multiwell scanning spectrometer. The titration curves obtained by the EIA for cells were practically similar to those obtained by the conventional 3H-thymidine (Tdr) uptake method, and the appropriate cell number to be used for the assay was indicated to be 3 to 50 x 10(3) cells per well. This method was applicable not only for quantitation of cell number of growing cells but also for measuring mitogenic responses of lymphocytes as revealed by the data obtained from Con A stimulation of lymphocytes. These results indicate that this new EIA method using anti-gp125 antibodies is useful for quantitative assays of cell growth and cell activation in the research fields of oncology and immunology.

Animals↗
PubMed1992

Studies on angiotensin converting enzyme inhibitors. VI. Synthesis and angiotensin converting enzyme inhibitory activities of the dicarboxylic acid derivative of imidapril and its diastereoisomers.

All possible diastereoisomers of the dicarboxylic acid (10a), the biologically active form of imidapril (1), were synthesized, and their inhibitory activity against angiotensin converting enzyme (ACE) was examined. The in vitro ACE inhibitory activity of these compounds greatly depended on the configurations of the three asymmetric carbons in each molecule. The (S,S,S) isomer (10a) showed much more potent activity than the others.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Pharmacokinetics of brain natriuretic peptide in rats.

The pharmacokinetics of rat brain natriuretic peptide (rBNP) was compared with that of alpha-rat atrial natriuretic peptide (alpha-rANP) in rats. After intravenous infusion in rats (600 pmol min-1kg-1 for 2 min), the disappearance of plasma rBNP was 4-fold slower than that of alpha-rANP. The estimated mean plasma clearance rates for rBNP and alpha-rANP were 45.9 ml min-1kg-1 and 74.4 ml min-1kg-1, respectively. The affinity of rBNP for the clearance receptor or degradation enzyme was considered to be lower than that of alpha-rANP.

Animals↗
PubMed1992

Effects of calphobindin II (annexin VI) on procoagulant and anticoagulant activities of cultured endothelial cells.

Effects of human placental calphobindin II (CPB-II) on the protein C activation and prothrombin activation on the cell surface of cultured calf pulmonary arterial endothelial cells have been investigated. CPB-II inhibited thrombin generation by factor Xa bound to the surface of the cultured endothelial cells in a dose-dependent manner. The amount (IC50) of CPB-II causing the inhibition at 50% was estimated to be approximately 10 nM. CPB-II was found to be ineffective, however, in the protein C activation by thrombin-thrombomodulin (TM) complex on the cell surface. Assay using purified TM revealed that CPB-II was able to exhibit the inhibitory potency for the protein C activation exclusively in the reconstituted system with negatively charged phospholipids. These results suggest that the neutral phospholipids participate in the protein C activation through the thrombin-TM system on the endothelial cell surface. The ability of CPB-II to inhibit procoagulant activity without affecting anticoagulant activity on the cultured endothelial cells is probably related to its potential physiological function, while it is able to exert various degrees of influence upon these activities in blood coagulation by interacting with negatively charged phospholipids in vitro.

Amino Acid Sequence↗
PubMed1992

Assay of cell surface-bound immunoliposomes using monoclonal antibody reactive with a cross-linking reagent.

A monoclonal antibody (mAb) reactive with a crosslinking reagent, N-(m-maleimidobenzoyl)dipalmitoylphosphatidylethanolamine (mMBPE), in liposomes was produced from a hybridoma clone established by a fusion between P3X63Ag8.653 mouse myeloma cells and spleen cells from a BALB/c mouse hyperimmunized with the antibody-coated liposomes containing mMBPE. Using this mAb (termed AL-6), the quantity of immunoliposomes bound on target tumor cells was assessed by flow cytofluorometry. The results obtained using fluorescein isothiocyanate-coupled AL-6 allowed the enumeration not only of the immunoliposomes bound on all tumor cells but also those on individual target tumor cells. The relevance of this assay method was confirmed by a comparison with another assay method of cell-bound liposomes using immunoliposomes containing carboxyfluorescein in the vesicles.

Animals↗
PubMed1992

[Effects of ambroxol HCl on the guinea pig tracheal mucous secretion and the rat pulmonary surfactant secretion].

The effects of orally administered ambroxol HCl (ambroxol) on guinea pig tracheal mucous secretion and rat pulmonary surfactant secretion were investigated histologically and biochemically. Ambroxol significantly increased the number of active goblet cells in guinea pig tracheal epithelium and total mucopolysaccharide level. Moreover, ambroxol significantly increased the neutral mucopolysaccharide level and PAS-positive substance in the guinea pig tracheal submucosal glands. Ambroxol did not show a significant effect on the content of the total phosphatidylcholine in rat lung lavage fluid, while ambroxol significantly increased the ratio of disaturated phosphatidylcholine to total phosphatidylcholine. From these results, it is suggested that ambroxol increases both the tracheal mucous secretion, especially the neutral mucopolysaccharide, and pulmonary surfactant secretion and these effects reflect part of the expectorant mechanism of the drug.

Ambroxol↗
PubMed1992

[Studies on angiotensin I converting enzyme (ACE) inhibitory effect of imidapril. (I). Inhibition of various tissue ACEs in vitro].

Imidapril is a newly synthesized non-sulfhydryl-containing angiotensin I converting enzyme (ACE) inhibitor. The present study describes the inhibitory effects of imidapril and its active metabolite 6366A on ACEs from various tissues and compares its effects to those of captopril, enalapril and enalaprilat in vitro. 6366A inhibited swine renal and human serum ACEs with an inhibition constant (Ki) of 0.067 nM and 0.04 nM, respectively. These values were 3 to 18 times more potent than those of the other inhibitors. The kinetic study showed that 6366A exerted competitive type inhibition. The ACE inhibition (IC50 values) of 6366A, enalaprilat and the structurally related compounds (6366DM and 6366PY) were compared in homogenates of lung, aorta, heart, brain and kidney from spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats (WKYs). The inhibitory effects of 6366A on all tissue ACEs from SHRs and WKYs were the most potent among these compounds. And the inhibitory potencies of these compounds were correlated with their chemical structure. The present results suggest that 6366A may show a strong inhibitory effect on ACEs from several tissues and species due to its chemical characteristics.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Cloning and sequence analysis of cDNA encoding Rhizopus niveus lipase.

Complementary DNA encoding Rhizopus niveus lipase (RNL) was isolated from the R. niveus IF04759 cDNA library using a synthetic oligonucleotide corresponding to the amino acid sequence of the enzyme. A clone, which had an insert of 1.0 kilobase pairs, was found to contain the coding region of the enzyme. The lipase gene was expressed in Escherichia coli as a lacZ fusion protein. The mature RNL consisted of 297 amino acid residues with a molecular mass of 32 kDa. The RNL sequence showed significant overall homology to Rhizomucor miehei lipase and the putative active site residues were strictly conserved.

Amino Acid Sequence↗
PubMed1992

Are there M cells in the cecal tonsil of chickens?

A unique morphological cell type, "microfold or membranous (M) cell-like cell", was detected electron-microscopically in the cecal tonsil epithelium of the chicken. M cell-like cells possessed a few short microvilli of irregular arrangement and a large number of lymphocytes and macrophages wedged into their basal surfaces. Triticum vulgaris was found to bind to M cell-like cells. With horseradish peroxidase (HRP) treatment, M cell-like cells showed an active HRP uptake just as did the neighbouring usual absorptive epithelial cells. No uptake of colloidal carbon particles from the intestinal lumen was recognized in any part of the intestinal epithelium. These results suggest that M cell-like cells of the chicken possess some M cell-characteristic morphological and histochemical features, but that their active uptake of foreign materials is not so developed as in mammalian M cells.

Animals↗
PubMed1992

Thyroxine-binding globulin variant (TBG-Kumamoto): identification of a point mutation and genotype analysis of its family.

Thyroxine-binding globulin (TBG) is the major thyroid hormone transport protein. Several inherited TBG variants resulting in partial or complete TBG deficiencies have been shown to be caused by either one or two nucleotide substitutions, or one nucleotide deletion in the coding regions of the TBG gene. In this report, a Japanese female patient (proband) with hyperthyroid state, whose lower TBG levels did not return to normal under the euthyroid state after treatment was examined. Genomic DNA samples from the proband with thyroxine-binding globulin deficiency (termed TBG-Kumamoto) and her family were subjected to the polymerase chain reaction, and the generated DNA fragments were sequenced. A single nucleotide substitution in the codon for the amino acid 363 of native TBG molecule (CCT to CTT) was found, resulting in the replacement of proline by leucine. It was revealed that the proband was a heterozygote and her father was a hemizygote. The mutation was confirmed by the allele-specific amplification of genomic DNAs from the proband and her father using oligonucleotide primers of normal or mutant residues at the 3' position in the polymerase chain reaction. These results indicate that the abnormality of TBG-Kumamoto is the consequence of this mutation. Genetically, this point mutation observed in TBG-Kumamoto might be classified as a new type of TBG deficiency.

Adult↗
PubMed1992

A Ca(2+)-independent protein kinase C, nPKC eta: its structure, distribution and possible function.

Protein kinase C consists of a protein family which can be classified into two major groups: Ca(2+)-dependent conventional protein kinase C and Ca(2+)-independent novel protein kinase C (nPKC). Among eight known members of protein kinase C family, we found that nPKC eta (eta) isolated from cDNA library of mouse skin, is most abundant in epithelial tissues including skin and epithelia of digestive and respiratory tracts. These data suggest potential role of this isoform in growth, differentiation and carcinogenesis of epithelial tissues.

Animals↗
PubMed1992

Basic approach to application of liposomes for cancer chemotherapy.

The method for augmentation of systemic in vivo anticancer effect of liposomes (Lip) containing adriamycin (ADM) and endocytosis activity of cancer cells to liposomal preparations have been studied. Encapsulation of ADM in liposomes increases its maximal tolerated dose and pretreatment of animals bearing tumor with tumor necrosis factor alpha (TNF) resulted in effective targeting of ADM-Lip to tumor, leading to its augmented therapeutic effect, but only when TNF and ADM-Lip were administered with an appropriate interval. All human tumor cell lines tested showed endocytosis activity to liposomes but the activity was differed among different tumor cell lines.

Animals↗
PubMed1992

Diminished acetylcholine-induced vasodilation in renal microvessels of cyclosporine-treated rats.

The mechanisms mediating cyclosporin A (CsA)-induced nephrotoxicity have not been established, but damage to endothelial cells by CsA has been proposed as an important factor. In the study presented here, whether endothelial cell function is impaired in the renal vasculature of CsA-treated rats is investigated. The vasodilatory effects of acetylcholine (ACH) on norepinephrine (NE)-induced microvascular constriction in isolated perfused hydronephrotic rat kidneys pretreated with CsA were therefore examined. Hydronephrosis was established to permit direct visualization of renal microvessels. Nephrotoxicity was induced by s.c. injection of CsA (60 mg/kg/day for 5 days). NE (0.3 microM)-induced afferent arteriolar (AA) constriction was exaggerated in CsA rats as compared with that in vehicle (olive oil)-treated control rats. (reduction in diameter of -34 +/- 3 (SE) versus -26 +/- 2%; P less than 0.05). Similarly, efferent arteriolar (EA) constriction by NE in CsA rats exceeded that of controls (-34 +/- 2 versus -22 +/- 3%; P less than 0.01). The vasodilatory responses evoked by ACH were blunted in CsA rats. The AA response to ACH in CsA rats was significantly decreased (P less than 0.005) at ACH concentrations from 1 nM to 1 microM. Similarly, ACH (1 nM to 100 nM) induced less EA vasodilation in CsA rats (P less than 0.025). In control and CsA rats, the addition of nitro-L-arginine abolished AA and EA vasodilation induced by ACH, suggesting that the sustained vasodilatory responses of AA and EA to ACH are mainly dependent on nitric oxide synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗