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H Nishimura

Publications and source records attributed to H Nishimura.

At least 235 records · Page 13Linked to original sources
PubMed1997

Angiotensin-independent mechanism for aldosterone synthesis during chronic extracellular fluid volume depletion.

Wild-type (Agt+/+) and homozygous angiotensinogen deletion mutant (Agt-/-) littermates were placed on normal (NS) or low Na diet (LS) for 2 weeks. Plasma aldosterone levels (P(aldo)) were comparable during NS, and similarly elevated during LS in Agt+/+ and Agt-/-. Moreover, in both, the elevation in P(aldo) was accompanied by marked increase in adrenal zona glomerulosa cells and adrenal P450aldo mRNA. Agt-/- mice were distinguished from Agt+/+ mice by their higher plasma K level, by approximately 1.5 and approximately 3.8 mEq/liter during NS and LS, respectively. Within the Agt-/- group, P(aldo) was directly proportional to plasma K. The importance of K for the hyperaldosteronism during dietary Na restriction was verified by the observation that superimposition of K restriction led to hypotension in Agt+/+ and uniform death in Agt-/- mice along with a reduction in P(aldo) by 75 and 90%, respectively. Thus, suppression of potassium, but not angiotensin, led to a marked attenuation of hyperaldosteronism during dietary Na restriction. Therefore, (a) a powerful angiotensin-independent mechanism exists for the hyperaldosteronism during LS; (b) high K is a central component of this mechanism; (c) contrary to current belief, the tonic effect of high K on aldosterone synthesis and release does not require an intact renin-angiotensin system; and (d) normally, intermediary feedback signals for hyperaldosteronism, i.e., both hypotension and high K, are effectively masked by aldosterone actions.

Adrenal Glands↗
PubMed1997

Predominant appearance of NK1.1+ T cells producing IL-4 may be involved in the increased susceptibility of mice with the beige mutation during Salmonella infection.

C57BL/6 mice with the beige mutation (beige mice) showed a high susceptibility to infection with Salmonella choleraesuis compared with C57BL/6 (B6) control mice, as assessed by bacterial number in the peritoneal cavity and the liver. The appearance of NK1.1+ CD3- NK cells was significantly suppressed, while NK1.1+ T cells were increased in the peritoneal cavity of beige mice after Salmonella infection. The expression level of IL-4 mRNA was much higher in freshly isolated NK1.1+ T cells of the infected beige mice, but the expression level of IFN-gamma mRNA was lower than that in the infected control mice. The NK1.1+ T cells produced more IL-4 in response to TCR alphabeta cross-linking, whereas IFN-gamma production upon TCR triggering was significantly impaired in the beige mice compared to that in the control mice. Furthermore, the generation of Salmonella-specific Th1 cells producing IFN-gamma was significantly inhibited in the peritoneal cavity of beige mice after Salmonella infection. However, administration of anti-IL-4 neutralizing mAb to beige mice during salmonellosis restored the generation of Salmonella-specific Th1 cells and decreased the susceptibility to Salmonella. These results suggested that the predominant activation of NK1.1+ T cells producing IL-4 over those producing IFN-gamma may be at least partly involved in the poor generation of Salmonella-specific protective Th1 cells, resulting in the increased susceptibility of beige mice to Salmonella infection.

Animals↗
PubMed1997

Interleukin-15 preferentially promotes the growth of intestinal intraepithelial lymphocytes bearing gamma delta T cell receptor in mice.

Several cytokines including stem cell factor (SCF) and interleukin (IL)-7 are known to be required for development of gamma delta T cell receptor (TCR) intestinal intraepithelial lymphocytes (i-IEL) in mice. We show here the effects of IL-15 on the proliferation and maintenance of murine gamma delta i-IEL in vitro. gamma delta i-IEL constitutively expressed a high level of IL-15 receptor alpha mRNA and proliferated in response to IL-15 more vigorously than alpha beta i-IEL. V gamma/delta repertoire analysis revealed that IL-15, like IL-2, induced polyclonal expansion of gamma delta i-IEL, whereas gamma delta i-IEL responding to IL-7 showed a V gamma/delta repertoire skewed towards V gamma 1/V delta 4, V delta 5. IL-15 efficiently prevented gamma delta i-IEL from apoptosis induced by growth factor deprivation. This rescue was accompanied by up-regulation of Bcl-2 expression. These results suggest that IL-15 plays important roles in proliferation and maintenance of gamma delta i-IEL.

Adjuvants, Immunologic↗
PubMed1997

Murine model of IgE production with a predominant Th2-response by feeding protein antigen without adjuvants.

Stimulation of systemic antigen-specific IgE production plays an important role in the mediation of food allergy; however, the mechanism of IgE production against food antigens is not fully understood. The development of relevant animal models may help to elucidate the pathogenesis of food allergy. We here show that DBA/2 mice receiving a casein diet without any adjuvant produced high levels of IgE specific for casein, accompanied by predominant Th2-like responses in liver lymphocytes, mesenteric lymph node cells and spleen cells. This model of IgE production produced by feeding protein antigen as a constituent of the diet can be applied to investigate the mechanism of IgE production and to develop reagents for controlling food allergy.

Animals↗
PubMed1997

Functional evaluation of hip abductor muscles with use of magnetic resonance imaging.

The hip abductor muscles are considered important for gait and biomechanics of the hip joint; however, their specific function has not been defined precisely. The intensity of magnetic resonance imaging signals in skeletal muscle has been reported to increase immediately after exercise. Making use of this phenomenon, we evaluated the hip abductor muscles. Magnetic resonance imaging was performed after isometric exercise of the hip abductor in three positions (20 degrees of abduction, neutral, and 20 degrees of adduction). The abduction force of the hip was measured with a dynamometer, and electromyographic measurements were made simultaneously for the same hip positions. Additionally, magnetic resonance imaging was performed after one-legged stance. As the hip was more adducted, the signal intensity increased on the scans. The values for muscle force, as evaluated with the dynamometer and integrated electromyography, also supported the results. The increase in signal intensity of the gluteus minimus at 20 degrees of abduction and after one-legged stance was significantly greater than that of the gluteus medius (p < 0.0001 and p < 0.0001, respectively). The results of this study indicate that the gluteus minimus muscle, along with the gluteus medius, plays an important role in hip abduction, gait, and stabilization of the pelvis.

Adult↗
PubMed1997

Lipopolysaccharide binding protein from normal human plasma purified with high efficiency.

Lipopolysaccharide (LPS)-binding protein (LBP) is an acute-phase plasma glycoprotein of 60 kDa which functions as an opsonin on activation of macrophages by bacterial LPS. The importance of LBP on the host defense against infection has been demonstrated. Human LBP has been purified from ascitic fluid or acute-phase serum. However, clinical samples often are not available, so we developed a method to purify LBP from normal plasma. The purification was accomplished by barium citrate precipitation, followed by three-step ion-exchange chromatography. The final step was Mono S cation-exchange chromatography, following Bio-Rex 70 and Mono Q chromatography, and it enabled the specific activity to increase overall 48,000-fold. This seems to be the first report of the use of Mono S column to purify LBP. The LBP obtained using these steps proved to be homogeneous by SDS-PAGE, Western blotting, and N-terminal sequence and amino acid composition analyses. The purification method established here will compensate when normal plasma with a low LBP content is available as the starting source.

Acute-Phase Proteins↗
PubMed1997

Ultrastructural changes during myocardial hypertrophy and its regression: long-term effects of nifedipine in adult spontaneously hypertensive rats.

Nifedipine (20 mg/kg/day) was given to 15-week-old spontaneously hypertensive rats for 20 weeks (SHR-N, n = 8). Comparison was done with sex-matched 15-week-old SHR (SHR-15, n = 7), untreated 35-week-old SHR (SHR-C, n = 10), 15-week-old normotensive Wistar-Kyoto rats (WKY-15, n = 15), and 35-week-old WKY (WKY-15, n = 5). Light and electron microscopic data on the subepicardial, middle and subendocardial layers and papillary muscles of the left ventricle were compared among the five rat groups. In SHR-N, blood pressure was significantly reduced by nifedipine, but was higher than in WKY-35 (199 +/- 11 mmHg vs 121 +/- 13 mmHg). The left ventricular weight/body weight ratio was much lower in SHR-N than in SHR-C, and was even below the baseline value in SHR-15. In addition, cardiac myocyte diameter was much smaller in each myocardial layer of SHR-N than in SHR-C, and was similar to the findings in SHR-15, but still larger than in WKY-35. The interstitial area ratio was markedly reduced in SHR-N and did not differ from that in SHR-15 or even WKY-15, while capillary density was significantly greater than in SHR-C and comparable to that in WKY-35. In SHR-C, large fibrotic foci were common, and many hypertrophic cardiac myocytes showed various degenerative changes including those of mitochondria and widening of the intermyofibrillar spaces. These changes were rarely seen in SHR-N. The intracellular volume ratio of myofibrils did not differ between SHR-N and WKY-35, but was significantly decreased in SHR-C, whereas that of mitochondria did not differ between SHR-N and SHR-C or WKY-35. These findings indicate that despite only a moderate suppression of hypertension, long-term nifedipine treatment caused regression of left ventricular hypertrophy, with cardiocyte hypertrophy, interstitial fibrosis, degenerative changes, and subcellular remodeling being reversed to the baseline levels in SHR-15. In addition, the capillary density was increased to that seen in WKY-35.

Animals↗
PubMed1997

Effects of methylprednisolone on hemodynamics and beta-adrenergic receptor signaling in rabbits with acute left ventricular failure.

Studies suggest that corticosteroids may restore the responsiveness to catecholamines in hypotensive patients. Since the significance of this promising intervention in congestive heart failure remains to be explored, we determined the effects of methylprednisolone, a potent activator of beta-adrenergic receptor signaling, on hemodynamics and beta-adrenergic receptor regulation in an animal model of heart failure. Acute left ventricular overloading was produced by aortic regurgitation (AR) in 22 Japanese white rabbits. Eleven animals received an intravenous administration of methylprednisolone (AR + PSL), while 11 received saline (AR + C) for 1 week. A sham operation was performed on 10 other rabbits (S). There was no difference between the AR + C and AR + PSL groups in the decrease in aortic diastolic pressure immediately after the production of AR. The aortic diastolic pressure and regurgitant fractions were also similar in the two groups. The left ventricular end-diastolic and end-systolic dimensions were both larger, and the left ventricular end-diastolic pressure was higher in AR + C or AR + PSL than in S rabbits. Between the AR + C and AR + PSL, there were no differences in any of these variables. Cardiac output was lower in AR + C, but not in AR + PSL, than in S. Cardiac output in AR + PSL was significantly higher than in AR + C. The myocardial concentration of norepinephrine and the number of beta-adrenergic receptors were both lower in the AR + C and AR + PSL than in the S groups. The number of receptors in AR + PSL was higher than in AR + C. Maximal isoproterenol-stimulated adenylyl cyclase activity was similar in the AR + C and AR + PSL groups. Results suggest methylprednisolone yielded some benefits, including an increase in cardiac output and in total beta-adrenergic receptor number, in this animal model of heart failure.

Animals↗
PubMed1997

Human leptin receptor gene in obese Japanese subjects: evidence against either obesity-causing mutations or association of sequence variants with obesity.

Leptin is an adipocyte-derived blood-borne satiety factor that acts on its cognate leptin receptor (Ob-R) in the hypothalamus, thereby regulating food intake and energy expenditure. To explore whether mutations in the Ob-R gene cause obesity in humans, we have searched for mutations in the gene for Ob-Rb, a biologically active receptor isoform, in obese Japanese subjects. We have also examined associations between such mutants and obesity in the Japanese. Genomic DNAs were used as templates in polymerase chain reaction (PCR) with primers selected to amplify exons 2 to 20 of the human Ob-Rb gene. Direct sequence analysis of the PCR products revealed 7 nucleotide sequence variants (Lys109Arg, Gln223Arg, Ser343Ser, Ser492Thr, Lys656Asn, Ala976Asp, and Pro1019Pro) in the Ob-Rb coding region from 17 obese Japanese subjects with a family history of obesity (BMI 39.3 +/- 8.4 kg/m2). No missense and nonsense mutations were found such as those in Zucker fatty (fa/fa) rats and Koletsky (fa[k]/ fa[k]) rats. Nucleotide substitutions occurred at relatively high frequencies at codons 109, 223, 976, and 1019 (79, 91, 100, and 85%, respectively). Allele frequency of each variant determined by PCR-RFLP and PCR-single strand conformation polymorphism analyses showed no significant differences between 47 obese (BMI 35.1 +/- 6.5 kg/m2) and 68 non-obese (BMI 21.6 +/- 2.2 kg/m2) subjects. The present study represents the first report of sequence variants of the Ob-Rb gene in the Japanese and provides evidence against either obesity-causing mutations or association of sequence variants with obesity in obese Japanese subjects.

Adolescent↗
PubMed1997

Angioimmunoblastic lymphadenopathy-like T-cell lymphoma. A case report and immunologic study.

BACKGROUND: Angioimmunoblastic lymphadenopathy (AILD) is rare in the head and neck and its definition remains controversial. METHOD: A case of AILD with an ulcer of the lateral pharyngeal wall was studied for viral infection, immunohistologic findings and T-cell receptor (TCR) V beta rearrangement. RESULTS: We observed elevation of antibodies against herpes simplex virus and herpes zoster virus as well as Epstein-Barr virus considered closely associated with AILD. The affected neck lymph node showed a preponderance of T-cells, predominantly CD4+ over CD8+ T-cells and all V beta gene families were expressed in the T-cells without enhancement of any particular TCR gene usage. CONCLUSION: Viral infection may occur easily in patients with AILD, possibly owing to immunodeficiency. Assessment of TCR V beta gene usage indicated T-cells to non-specifically become lymphomatous in AILD-like T-cell lymphoma.

Aged↗
PubMed1997

Comparison between magnetization transfer contrast and fast spin-echo MR imaging of degenerative disease of the cervical spine at 0.3 T.

We compared magnetization transfer contrast (MTC) with gradient recalled echo (GRE) magnetic resonance imaging (MRI) and fast spin-echo (FSE) MRI of the degenerative cervical spine at 0.3 T. Fifty patients with suspected degenerative disease of the cervical spine were prospectively evaluated. Multislice sagittal and axial images of the cervical spine were obtained using MTC GRE sequence [repetition time (TR)/echo time (TE)/flip angle = 750/23/25 degrees] and FSE sequence with peripheral gating (TR/effective TE = 2000-4000/120). Quantitatively, FSE showed higher signal-to-noise ratio and superior disk contrast between normal and degenerative disks, while MTC images showed superior contrast-to-noise ratio for the cerebrospinal fluid (CSF) versus cord and superior CSF homogeneity. In qualitative analysis, similar results were obtained. In conclusion, FSE and MTC GRE sequences are MRI techniques of imaging the cervical spine that have different characteristics and supplement each other in the diagnostic imaging of degenerative disease of the cervical spine.

Adult↗
PubMed1997

Quantification of thigmotropism (contact sensing) of Candida albicans and Candida tropicalis.

To quantify the thigmotropism, we adapted the our previous method using a chemotaxifilter system in combination with a bioluminescent adenosine triphosphate (ATP) assay based on firefly luciferase-luciferin system and analyzed the relationship between the ability of germ tube formation and thigmotropism of C. albicans and C. tropicalis. Both the ability to form germ tube and the amount of hyphae exhibiting thigmotropism varied depending upon both the species and strains of Candida. C. albicans formed more germ tubes than C. tropicalis. A good correlation was observed between the ability to form a germ tube and the capacity for thigmotropism, and the results gave a level of significance (p < 0.05). Further, SEM observation revealed that relatively long hyphae of C. tropicalis with penetrated through the pores of filter membrane. This phenomenon may be of importance in the development of pathogenesis of C. tropicalis as well as C. albicans.

Candida↗
PubMed1997

Effects of dietary sugars and, saliva and serum on Candida bioflim formation on acrylic surfaces.

The effect of two dietary sugars, glucose and galactose, on biofilm formation of the oral fungal pathogen Candida on denture acrylic strips coated with saliva and serum pellicles was examined in vitro using Candida albicans (3 isolates), C. glabrata (2 isolates) and C. tropicalis (2 isolates). The degree of biofilm activity was affected by both the dietary sugar and the nature of the pellicle (ANOVA, p < 0.01). With most isolates the glucose grown yeasts demonstrated significantly more bioflim activity than the galactose grown fungi, in the presence of pellicles (ANOVA, p < 0.01 or P < 0.01). In contrast, one isolate of galactose-grown yeast elicited significantly higher biofilm activity than glucose-grown yeasts on the control strips (ANOVA, p < 0.01). Taken together, these results imply that a saliva or a serum pellicle, and the carbon source in the environment, act a complex manner modulating Candida bioflim formation.

Acrylic Resins↗
PubMed1997

Anti-inflammatory activity of superoxide dismutase conjugated with sodium hyaluronate.

Superoxide dismutase (SOD) from bovine erythrocytes was conjugated with sodium hyaluronate (HA) with a mean molecular weight of 10(6) to have greater anti-inflammatory activity in vivo. Amino groups of SOD were coupled with carboxyl groups in the hyaluronate molecule using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide. The HA-SOD conjugate was composed of 1.5 mol of SOD molecule per 1 mol of hyaluronate on the average, and retained 70% of the activity of unmodified SOD. The conjugate was essentially non-immunogenic in mice, and exhibited much higher anti-inflammatory activities than HA or SOD in models of inflammatory diseases such as ischemic oedema of the foot-pad in mice, carrageenin-induced pleurisy and adjuvant arthritis in rats.

Animals↗
PubMed1997

A novel in vivo mechanism for angiotensin type 1 receptor regulation.

This study examined whether a regulatory mechanism exists for the angiotensin II receptor that is compatible with in vivo homeostatic need. Experiments were conducted under two different experimental stresses, (1) deletion of receptor protein and (2) chronic extracellular fluid (ECF) volume depletion. To circumvent potentially dampening intermediary feedback signals in vivo, any feedback gain was completely averted through genetic engineering. The coding exon of angiotensin type 1A (AT1A) receptor gene (Agtr1a) was targeting-replaced with a reporter gene, lacZ, so that the transcription of lacZ, instead of Agtr1a, is driven by the native Agtr1a promoter. ECF volume depletion by dietary sodium restriction enhanced Agtr1a gene expression in the adrenal gland of wild-type mice. However, although blood pressure fell in the homozygous targeted mice, Agtr1a gene expression remained unchanged in the adrenal, indicating that adrenal Agtr1a gene expression is regulated entirely through angiotensin receptor-ligand interactions. In the kidney, AT1A mRNA assessed by Northern blotting also did not change in AT1A null-mutated mice with or without sodium restriction. However, tissue examinations for lacZ mRNA and activities indicated that sodium restriction and receptor protein depletion result in dramatic up-regulation of Agtr1a gene expression within the renal arterioles, which can be nullified by an experimental normalization of blood pressure. No such change was observed in wild-type mice. This study demonstrates a presence within the resistance vessel of a blood pressure-sensitive mechanism for AT1 receptor regulation that opposes a down-regulatory influence of the ligand during ECF volume depletion.

Adrenal Glands↗
PubMed1997

Nonadipose tissue production of leptin: leptin as a novel placenta-derived hormone in humans.

Leptin is a circulating hormone that is expressed abundantly and specifically in the adipose tissue. It is involved in the regulation of energy homeostasis, as well as the neuroendocrine and reproductive systems. Here, we demonstrate production of leptin by nonadipose tissue, namely, placental trophoblasts and amnion cells from uteri of pregnant women. We show that pregnant women secrete a considerable amount of leptin from the placenta into the maternal circulation as compared with nonpregnant obese women. Leptin production was also detected in a cultured human choriocarcinoma cell line, BeWo cells, and was augmented during the course of forskolin-induced differentiation of cytotrophoblasts into syncytiotrophoblasts. Plasma leptin levels were markedly elevated in patients with hydatidiform mole or choriocarcinoma and were reduced after surgical treatment or chemotherapy. Leptin is also produced by primary cultured human amnion cells and is secreted into the amniotic fluid. The present study provides evidence for leptin as a novel placenta-derived hormone in humans and suggests the physiologic and pathophysiologic significance of leptin in normal pregnancy and gestational trophoblastic neoplasms.

Adipose Tissue↗
PubMed1997

Cell cycle arrest and apoptosis of leukemia cells induced by L-asparaginase.

Apoptotic cell death of murine leukemia cells induced by E. coli L-asparaginase was studied. Deprivation of L-asparagine from the culture of L5178Y cells by L-asparaginase caused the fragmentation of chromosomal DNA of the leukemia cells within 24 h. Prior to the degradation of DNA, cell cycles of L5178Y cells were found to be arrested in G1 phase, and evidence of the DNA strand breaks was initially observed in G1 phase cells as early as 8 h after the asparaginase treatment. Therefore, apoptosis of leukemia cells induced by L-asparaginase is an event that is associated with the cell cycle arrest in G1 phase.

Animals↗