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H Nishimura

Publications and source records attributed to H Nishimura.

At least 109 records · Page 6Linked to original sources
PubMed2000

Effect of serum concentration on Candida biofilm formation on acrylic surfaces.

The biofilm formation of the oral fungal pathogen Candida on denture acrylic strips coated with saliva, serum and, saliva-serum pellicle were examined in vitro using Candida albicans (four isolates), Candida glabrata (three isolates) and Candida tropicalis (three isolates). The degree of biofilm activity varied depending upon both the isolate and the pellicle. Significantly increased biofilm activity on the pellicle (particularly serum)-coated strips was observed with three isolates of C. albicans and another of C. glabrata on protein-coated acrylics, with increasing concentration of serum in the pellicle. Similar trends were observed with one isolate of C. albicans and C. glabrata, although the effects of pellicles were not significant. In contrast, with all three isolates of C. tropicalis and a single isolate of C. glabrata, although the biofilm activity on the protein-free control strips was significantly higher than that of saliva-coated strips, the increase in activity of pellicle-admixed biofilm depended upon the serum concentration. Candidal biofilm formation on acrylic surfaces is essentially promoted with increasing concentration of serum in the pellicle. This suggests that inflammation in the oral environment would facilitate fungal colonization on denture acrylic.

Acrylic Resins↗
PubMed2000

Cutaneous metallothionein induction by ultraviolet B irradiation in interleukin-6 null mice.

The mediators of cutaneous metallothionein induction by ultraviolet radiation have not been defined. In this study we sought to identify cytokines that might be involved. We examined the role of interleukin-6, using the IL-6 null (IL-6-/-) mouse, which has been observed to be highly sensitive to ultraviolet radiation damage. Whereas cutaneous metallothionein concentration, measured by radioimmunoassay, began to rise in wild-type (IL-6+/+) mice by 12 h after ultraviolet irradiation, there was a significant delay in the IL-6-/- mice until 48 h after UV irradiation. Immunohistologically, metallothionein appeared in IL-6+/+ mice at 24 h in dermal fibroblasts, and then by 48 h in epidermal basal keratinocytes, with intensity increasing until 72 h, and was coincident with proliferating cell nuclear antigen-positive staining. Corresponding metallothionein expression in IL-6-/- mouse skin was significantly delayed. Serum interleukin-6 was elevated in IL-6+/+ mice following ultraviolet irradiation, with peak concentration at 4 h, but no increase in serum interleukin-1beta was found in either IL-6+/+ or IL-6-/- mice. Interestingly, tumor necrosis factor alpha concentration in serum was elevated at 12 h postirradiation in IL-6+/+ mice, but there was an earlier (at 4 and 8 h) time-dependent increase in tumor necrosis factor alpha in serum of the IL-6-/- mice. Skin zinc and copper concentrations were not altered by ultraviolet irradiation in either IL-6+/+ or IL-6-/- mice. The results suggest that interleukin-6 may be a very early mediator of cutaneous metallothionein induction by ultraviolet radiation, but that this role is possibly assumed by alternative cytokines like tumor necrosis factor alpha when interleukin-6 is deficient.

Animals↗
PubMed2000

The angiotensin type II receptor tonically inhibits angiotensin- converting enzyme in AT2 null mutant mice.

BACKGROUND: Pharmacologic inhibition of the angiotensin-converting enzyme (ACE) limits angiotensin II (Ang II)-induced vasoconstriction and cellular proliferation. There is emerging evidence that some of the beneficial effects of ACE inhibitors may be endogenously available through the angiotensin receptor type 2 (AT2). METHODS: To evaluate whether AT2 modulates ACE activity, we used an high-performance liquid chromatography (HPLC)-based enzymatic assay in tissues from AT2 knockout mice (Agtr2-/y) and cultured cells. These studies were complimented by physiologic studies of pharmacologic inhibition of AT2. RESULTS: Circulating (C) and tissue ACE activities in heart (H), lung (L), and kidney (K) were doubled in Agtr2-/y mice compared with wild-type mice [162.9 +/- 17.6 mU/mL (C), 97.7 +/- 20.7 (H), 6282.1 +/- 508.3 (L), and 2295.0 +/- 87.0 (K) mU/g tissue for Agtr2-/y vs. 65.3 +/- 35.4 mU/mL (C), 44.5 +/- 8.7 (H), 3392.4 +/- 495.2 (L), and 1146.1 +/- 217.3 (K) mU/g tissue for wild-type mice, P < or = 0.05, 0.025, 0.002, and 0.0001, respectively]. Acute pharmacologic inhibition of AT2 [PD123319 (PD), 50 microg/kg/min, i. v.] significantly increased ACE activity in kidneys of wild-type mice (1591.2 +/- 104.4 vs. 1233.6 +/- 88.0 mU/g tissue in saline-infused mice, P < 0.05; P < 0.01 vs. uninfused, wild-type mice). Moreover, ACE activity increased in A10 cells exposed to PD (10-6 mol/L) together with Ang II (10-7 mol/L), but not with an AT1 antagonist (losartan, 10-6 mol/L). This heightened ACE activity appears functionally relevant because infusion of angiotensin I caused more prompt hypertension in Agtr2-/y mice than in wild-type littermates. Likewise, infusion of bradykinin, also a substrate for ACE, caused significantly less hypotension in Agtr2-/y mice than controls. CONCLUSIONS: These studies indicate that AT2 functions to decrease ACE activity tonically, which may, in part, underlie AT2's increasingly recognized attenuation of AT1-mediated actions.

Angiotensin I↗
PubMed2000

Genetic regulation of anti-erythrocyte autoantibodies and splenomegaly in autoimmune hemolytic anemia-prone new zealand black mice.

New Zealand Black (NZB) mice spontaneously produce anti-erythrocyte autoantibodies (AEA) in association with splenomegaly, thus serving as a model for autoimmune hemolytic anemia. Although these autoimmune traits are inherited as a dominant fashion, expression in F(1) hybrids of NZB and most non-New Zealand strains is suppressed due to the contribution of wild-type modifying genes present in the latter strains. Using chromosomal microsatellite markers in the (C57BL/6 x NZB)F(1) x NZB backcross progeny, we mapped C57BL/6 modifying loci for AEA production and splenomegaly. Generation of AEA was found to be down-regulated by a combined effect of two major independently segregating dominant alleles-one linked to D7MIT30 on chromosome 7 and the other linked to D10MIT42 on chromosome 10. Splenomegaly was modified mainly by a single C57BL/6 allele linked to D4MIT58 on chromosome 4. Thus, the autoimmune hemolytic anemia in the NZB strain is under multigenic control and a combined action of not only susceptibility but also modifying alleles with suppressive activities affects the outcome of disease features in the progeny. There are potentially important candidate genes which may be linked to the regulation of AEA and splenomegaly.

Anemia, Hemolytic, Autoimmune↗
PubMed2000

Structural analysis of N-linked sugar chains of human blood clotting factor IX.

The structures of N-glycans of human blood clotting factor IX were studied. N-Glycans liberated by hydrazinolysis were N-acetylated and the reducing-end sugar residues were tagged with 2-aminopyridine. The pyridylamino (PA-) sugar chains thus obtained were purified by HPLC. Each PA-sugar chain was analyzed by two-dimensional sugar mapping combined with glycosidase digestion. The major structures of the N-linked sugar chains of human factor IX were found to be sialotetraantennary and sialotriantennary chains with or without fucose residues. These highly sialylated sugar chains are located on the activation peptide of the protein.

Carbohydrate Sequence↗
PubMed2000

Changes in mint1, a novel synaptic protein, after transient global ischemia in mouse hippocampus.

Mints (munc18-interacting proteins) are novel multimodular adapter proteins in membrane transport and organization. Mint1, a neuronal isoform, is involved in synaptic vesicle exocytosis. Its potential effects on development of ischemic damage to neurons have not yet been evaluated. The authors examined changes in mint1 and other synaptic proteins by immunohistochemistry after transient global ischemia in mouse hippocampus. In sham-ischemic mice, immunoreactivity for mint1 was rich in fibers projecting from the entorhinal cortex to the hippocampus and in the mossy fibers linking the granule cells of the dentate gyrus to CA3 pyramidal neurons. Munc18-1, a binding partner of mint1, was distributed uniformly throughout the hippocampus, and synaptophysin 2, a synaptic vesicle protein, was localized mainly in mossy fibers. After transient global ischemia, mint1 immunoreactivity in mossy fibers was dramatically decreased at 1 day of reperfusion but actually showed enhancement at 3 days. However, munc18-1 and synaptophysin 2 were substantially expressed in the same region throughout the reperfusion period. These findings suggest that mint1 participates in neuronal transmission along the excitatory pathway linking the entorhinal cortex to CA3 in the hippocampus. Because mint1 was transiently decreased in the mossy fiber projection after ischemia, functional impairment of neuronal transmission in the projection from the dentate gyrus to CA3 pyramidal neurons might be involved in delayed neuronal death.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Expression of mouse mammary tumor virus superantigen accelerates tumorigenicity of myeloma cells.

To investigate whether superantigen (SAG) from endogenous mouse mammary tumor virus functions as an immunogenic or a tumorigenic factor in tumor development, the BALB/c myeloma cell line FO was transfected with the SAG gene from the 3' Mtv-50 long terminal repeat (LTR) open reading frame (ORF), the product of which was specific for Vbeta6. All five transfectants expressing Mtv-50 LTR ORF mRNA showed stimulatory activity for Vbeta6 T-cell hybridomas in vitro; this activity was inhibited by the addition of anti-Mtv-7 monoclonal antibody (MAb) or anti-major histocompatibility complex class II I-A(d) and I-E(d) MAb. All transfectants with the SAG gene grew more rapidly than did mock transfectants in BALB/c mice after subcutaneous inoculation, whereas all clones, including mock transfectants, grew equally well in athymic nude mice. A significant fraction of Vbeta6 T cells selectively expressed activation markers, including CD44(high), CD62L(low), and CD69(high), and produced large amounts of interleukin 5 (IL-5) and IL-6 in BALB/c mice inoculated with transfectants. These results suggested that the expression of viral SAG enhances the tumorigenicity of a myeloma cell line through the stimulation of SAG-reactive T cells.

Animals↗
PubMed2000

Control of catecholamine release and blood pressure with octreotide in a patient with pheochromocytoma: a case report with in vitro studies.

A 65-year-old male patient with pheochromocytoma, whose hypertensive episodes were uncontrolled using conventional therapy, was successfully treated with octreotide (SMS 201-995). The serum catecholamine level and the urinary excretion of catecholamines decreased after 300 microgram/day of octreotide was administered. To clarify the mechanisms of octreotide that lower catecholamine released from a tumor, we studied the in vitro effects of octreotide on membrane potentials and voltage-dependent Ca(2+) channel (VDCC) current using the whole-cell patch-clamp technique in single pheochromocytoma cells dispersed after tumor resection. The action potentials were reversibly inhibited with 10 microM octreotide. In addition, the VDCC current evoked by depolarized pulses from the holding potential of -60 mV was inhibited with 10 microM octreotide. Octreotide is useful for controlling blood pressure before surgery in some patients with uncontrolled hypertension caused by a pheochromocytoma.

Adrenal Gland Neoplasms↗
PubMed2000

New imaging findings in a patient with central nervous system dysfunction after bone marrow transplantation.

Central nervous system disorders are an important complication of bone marrow transplantation (BMT). We have recently performed cerebral angiography to examine central nervous system dysfunction in a 22-year-old woman with acute lymphoblastic leukaemia who had undergone BMT. Angiography demonstrated multiple stenoses and occlusions in the peripheral branches of the anterior and middle cerebral arteries, a pattern similar to that seen in vasculitis. She was thought to most likely have cytomegalovirus (CMV) vasculitis, but other forms of vasculitis, such as angiitis-like-syndrome-associated graft-versus-host disease could not be excluded. This case suggests that CMV vasculitis may cause central nervous system dysfunction after BMT and that imaging studies may provide useful information about central nervous system disorders in these patients.

Adult↗
PubMed2000

Immune tolerance induced by polyethylene glycol-conjugate of protein antigen: clonal deletion of antigen-specific Th-cells in the thymus.

Polyethylene glycol (PEG) conjugates of protein antigens induce antigen-specific immune tolerance of helper T (Th)-cells. However, the mechanism of this Th-cell tolerance has remained unelucidated. Using transgenic mice with ovalbumin (OVA)-specific T-cell receptor (TCR) genes, we examined the response of OVA-specific Th-cells towards tolerogenic PEG-conjugate of OVA in vitro and in vivo. When stimulated with PEG--OVA in vitro, transgenic OVA-specific Th-cells proliferated and produced interleukin 2, the levels of which were comparable to those induced by unmodified OVA. In contrast, PEG--OVA administered into the circulation of transgenic mice induced unresponsiveness in peripheral OVA-specific Th-cells. Moreover, in the thymus of these transgenic mice, the frequency of immature CD4+CD8+ (double positive) thymocytes was reduced. A similar phenomenon was not observed in transgenic mice treated with unmodified OVA. As autoreactive T-cells are known to be clonally deleted at the immature double positive stage in the thymus. Th-cell tolerance induced by PEG--protein antigens is at least in part mediated by central tolerance in the thymus, and is likely caused by the markedly enhanced stability of PEG--protein conjugates in the circulatory system.

Animals↗
PubMed2000

Seven-color fluorescence imaging of tissue samples based on Fourier spectroscopy and singular value decomposition.

Seven-color analyses of immunofluorescence-stained tissue samples were accomplished using Fourier spectroscopy-based hyperspectral imaging and singular value decomposition. This system consists of a combination of seven fluorescent dyes, three filtersets, an epifluorescence microscope, a spectral imaging system, a computer for data acquisition, and data analysis software. The spectra of all pixels in a multicolor image were taken simultaneously using a Sagnac type interferometer. The spectra were deconvolved to estimate the contribution of each component dye, and individual dye images were constructed based on the intensities of assigned signals. To obtain mixed spectra, three filter sets, i.e., Bl, Gr, and Rd for Alexa488 and Alexa532, for Alexa546, Alexa568, and Alexa594, and for Cy5 and Cy5.5, respectively, were used for simultaneous excitation of two or three dyes. These fluorophores have considerable spectral overlap which precludes their separation by conventional analysis. We resolved their relative contributions to the fluorescent signal by a method involving linear unmixing based on singular value decomposition of the matrices consisting of dye spectra. Analyses of mouse thymic tissues stained with seven different fluorescent dyes provided clear independent images, and any combination of two or three individual dye images could be used for constructing multicolor images.

Animals↗
PubMed2000

Electron-microscopic study of the bactericidal effect of OPB-2045, a new disinfectant produced from biguanide group compounds, against methicillin-resistant Staphylococcus aureus.

The bactericidal effect of OPB-2045, a new disinfectant produced from biguanide group compounds, against methicillin-resistant Staphylococcus aureus (MRSA), MRSA IID 1677, was investigated by transmission electron microscopy. OPB-2045 showed strong bactericidal activity against MRSA. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of OPB-2045 against the test strain were 0.78 and 1.56 microg mL(-1), respectively. The test bacteria were incubated in the presence of OPB-2045 at 1/2 MIC (0.39 microg mL(-1)), 1 MIC (0.78 microg mL(-1)), 2 MIC (1 MBC, 1.56 microg mL(-1)), 4 MIC (2 MBC, 3.13 microg mL(-1)) or 10 MIC (5 MBC, 7.8 microg mL(-1)) at 37 degrees C for 30 s, 3 min, 30 min or 6h. The morphology of the cells was examined by transmission electron microscopy. The cell damage observed after 30-min or 6-h incubation in the presence of OPB-2045 at 1/2 or 1 MIC was the same as that at 2, 4 or 10 MIC. The numbers of damaged MRSA cells increased according to the increase in concentration of added disinfectant, and the image of bacteriolysis was observed, too. After treatment at 1/2 or 1 MIC, a few leaking cells were recognized, but no destroyed cells were found. No morphological changes were observed after treatment at 1 or 2 MIC for 30 s, 3 min or 30 min. When the incubation time was extended to 6 h, morphological changes in the MRSA cells treated at 1 or 2 MIC were observed. When examining the relationship between the numbers of surviving bacteria and the MIC (MBC) values in soybean casein digest broth, no decrease in MRSA cell numbers was recognized in the untreated control or at 1/2 MIC, but a marked decrease in MRSA cell numbers was recognized as the OPB-2045 concentration was increased. The new disinfectant OPB-2045 would make a useful contribution to the medical field for the prevention of infections caused by pathogenic bacteria such as MRSA.

Anti-Infective Agents, Local↗
PubMed2000

Osteopontin expression in spontaneously developed neointima in fowl (Gallus gallus).

Fowl show spontaneous elevation of blood pressure and neointimal plaque formation in the abdominal aorta at young ages. A similar neointima can be induced by a balloon-catheter-induced endothelium injury to the fowl aorta. Both spontaneously developed and injury-induced vascular lesions exhibit subendothelial hyperplasia consisting of neointimal cells with a synthetic phenotype and abundant extracellular matrix. The role of the extracellular matrix in the formation of neointima is not known. In this study, we investigated whether osteopontin, an adhesive glycoprotein present in the extracellular matrix, is expressed in aortic smooth muscle tissue of the fowl abdominal aorta, in spontaneously developed neointimal plaques and in the aortic smooth muscle underlying neointimal plaques. Crude protein extracted from isolated aortic smooth muscle tissues and neointimal plaques was fractionated by SDS-polyacrylamide gel electrophoresis and analyzed by immunoblotting with rabbit anti-fowl osteopontin (provided by Dr L. C. Gerstenfeld, Boston University) or anti-&agr; smooth muscle actin antibodies. The anti-fowl osteopontin antibody predominantly recognized a 66-70 kDa protein band in neointimal plaques that co-migrated with the osteopontin phosphoprotein from chick bone. In contrast, intact aortic smooth muscle and the smooth muscle underlying neointimal plaques equally expressed three proteins (66-70 kDa, approximately 50 kDa and approximately 43 kDa) recognized by the anti-osteopontin antibody. Anti-&agr; smooth muscle actin antibody recognized a 43 kDa protein band, and the expression of &agr; smooth muscle actin was higher in aortic smooth muscle than in neointimal plaques. Osteopontin mRNA expression was examined using reverse transcription-polymerase chain reaction (RT-PCR) of total RNA from vascular tissues with specific primers constructed on the basis of the reported fowl osteopontin nucleotide sequence. The PCR products from intact aortic smooth muscle and neointimal plaques correspond to the product from recombinant plasmid cDNA (a gift from Dr L. C. Gerstenfeld) transcribed in vitro. These results suggest that osteopontin is synthesized in intact aortic smooth muscle and neointimal plaques in fowl and that unmetabolized approximately 66 kDa osteopontin protein is a predominant form in the neointima, indicating that osteopontin protein may be actively synthesized in the neointima.

Animals↗
PubMed2000

Serum levels of vascular endothelial growth factor and transforming growth factor-beta1 in patients with atrial fibrillation undergoing defibrillation therapy.

We have previously reported that pulsatile mechanical stretch in vitro induced rapid secretion of vascular endothelial growth factor (VEGF) by cultured cardiac myocytes and that the stretch-induced secretion of VEGF was mainly mediated by secretion of transforming growth factor (TGF)-beta1 by cardiac myocytes in an autocrine fashion. To investigate whether tachycardia-induced mechanical overload increases serum levels of VEGF and TGF-beta1, we investigated the serum levels of VEGF and TGF-beta1 in patients with atrial fibrillation undergoing defibrillation therapy. The serum VEGF level before defibrillation was significantly increased in 13 out of 20 patients (89.48 +/- 16.09 pg/ml [mean +/- SE]). After defibrillation, the serum VEGF level in these 13 patients significantly (p = 0.019) decreased (65.04 +/- 16.61 pg/ml [mean +/- SE]), although it increased slightly in one patient. The serum TGF-beta1 level before defibrillation therapy (13.01 +/- 1.97 pg/ml [mean +/- SE]) in these 12 patients also decreased after defibrillation therapy (11.47 +/- 2.06 pg/ml [mean +/- SE]). The changes in serum VEGF level significantly correlated with those in the serum TGF-beta1 level in these 12 patients (r = 0.73, p < 0.05, n = 12). Our data suggest that tachyarrhythmia-induced mechanical overload can increase the serum VEGF level, which can be a useful clinical marker for relative myocardial oxygen shortage in such patients.

Aged↗
PubMed2000

Constitutively active mitogen-activated protein kinase kinase increases GLUT1 expression and recruits both GLUT1 and GLUT4 at the cell surface in 3T3-L1 adipocytes.

To address a role of mitogen-activated protein kinase (MAPK) in the regulation of glucose transport, we made a constitutively active mutant of MAPK kinase (MAPKK) and introduced it into 3T3-L1 preadipocytes by using a retrovirus-mediated transfection procedure. The deletion of 20 amino acids (those between and including 32 and 51) in the amino terminal region of Xenopus MAPKK and the replacement of serine residues on the 218 and 222 positions by glutamic acid (dSESE-MAPKK) let Xenopus MAPKK constitutively active. The isolated cell clones differently expressing dSESE-MAPKK (clone 219 higher expression, clone 233 lower expression) efficiently differentiated to adipocytes by a standard differentiation cocktail. Accordingly, the increased expression of dSESE-MAPKK protein during differentiation resulted in the increased basal MAPK activity in clone 219 adipocytes and, to a lesser extent, in clone 233 adipocytes. In contrast to clone 233 and parental adipocytes, basal 2-deoxyglucose uptake was enhanced fourfold in clone 219 adipocytes, in accordance with increased expression of GLUT1 mRNA and protein. Whereas GLUT4 mRNA was similarly expressed in all of the adipocytes, GLUT4 protein appeared to decrease in clone 219 adipocytes. More importantly, subcellular fractionation studies showed that the localization of both GLUT1 and GLUT4 in the plasma membranes (PMs) was markedly increased in the basal state in clone 219 adipocytes compared with that in clone 233 and parental adipocytes, in which both glucose transporters were preferentially located in intracellular compartments. Consequently, insulin-induced translocation of GLUT1 was abolished in clone 219 adipocytes, although the remaining intracellular GLUT4 was still responsive to insulin stimulation, which led to the movement to the PM. As combined effects on the situation of GLUT1 and GLUT4, the foldness of insulin stimulation of glucose transport based on the basal activity was reduced in cells expressing constitutively active MAPKK. These results imply that chronic activation of MAPK could be one of the mechanisms for insulin resistance.

3T3 Cells↗
PubMed2000

Practical approaches to determining disease-susceptible loci in multigenic autoimmune models.

Linkage analysis using polymorphic DNA markers has paved the way toward the identification of genes responsible for rare recessive traits and for the susceptibility to certain tumors in humans. However, genetic susceptibility to common diseases, including systemic autoimmune diseases, is difficult to determine, hence has remained a challenging problem in the field of molecular genetics. Elucidation of multiple quantitative trait loci that predispose individuals to multi-phenotypic systemic autoimmune disease requires formidable research efforts, and there is a growing consensus that mouse models are required. This review provides a guide to methods that can be used in linkage studies of autoimmune mice. Mouse studies in relation to recent advances in bio-informatics are also discussed.

Animals↗
PubMed2000

Nitric oxide mediates inhibitory effect of losartan on angiotensin-induced contractions in hamster but not rat aorta.

We investigated a possible contribution of nitric oxide (NO) and prostaglandins to the inhibitory effect of losartan on contractions to Ang I (10(-6) M) and Ang II (10(-7) M) with or without L-NAME (10(-4) M) or indomethacin (10(-5) M) in the aorta of WKY, SHR and hamster (n=7 each). Rings of thoracic aorta (2-mm long) were placed in a myograph (5 ml). Endothelium-dependent vasodilations were evaluated with acetylcholine (10(-8) to 10(-6) M). After a 45-minute incubation with L-NAME under a resting tension of 2 g, only hamster aorta contracted (p<0.01). The SHR aorta showed impaired relaxations to acetylcholine compared with the WKY and hamster aorta (p<0.05). Despite the difference in the stimulated NO release, losartan completely abolished the responses to Ang I and Ang II both in WKY and SHR vessels irrespective of the presence of L-NAME. In contrast to the rat aorta, the inhibitory effect of losartan was attenuated in the presence of L-NAME in the hamster aorta (78% vs 99% inhibition, p<0.05). Indomethacin did not alter the effect of losartan in any vessels. Our results suggest that the presence of NO, particularly a basal secretion of NO, is necessary for the full expression of the inhibitory effect of losartan in the hamster, but not in WKY or SHR, aorta. Unlike NO, prostaglandins do not appear to play a role in the effect of losartan.

Angiotensins↗