Search PubMed⌕ Search

Biomedical subjects

M Shimoyama

Publications and source records attributed to M Shimoyama.

At least 19 recordsLinked to original sources
PubMed2005

Increased sensitivity to acute and persistent pain in neuron-specific endothelin-1 knockout mice.

Endothelin-1 (ET-1) exists in endothelial cells as well as a variety of other cell types. The presence of ET-1 and its receptors in neurons suggests its possible role as a neurotransmitter and/or neuromodulator. Studies utilizing exogenous ET-1 have suggested that ET-1 affects pain transmission. This study was designed to examine the possible role(s) of neuronal ET-1 in pain processing. We produced neuron-specific ET-1 knockout mice using the Cre/loxP system with a synapsin I promoter and examined the effects produced by the lack of neuronal ET-1 on pain behavior using common pain models and a model of stress-induced analgesia. In acute nociceptive pain models, paw withdrawal thresholds to radiant heat and mechanical stimuli applied with von Frey hairs were significantly lower in the knockout mice compared with control. This indicated that the absence of neuronal ET-1 leads to greater sensitivity to acute nociceptive stimuli. After inflammation was produced by intraplantar injection of carrageenan, there was a significantly greater degree of thermal hyperalgesia and mechanical allodynia in the knockout mice even after the difference in baseline values was compensated. Furthermore, in a neuropathic pain model produced by spinal nerve ligation, there was also a greater degree of mechanical allodynia in the knockout mice. Finally, in a swim-stress model, the magnitude of stress-induced analgesia was less in the knockout mice, indicating the involvement of neuronal ET-1 in stress-induced analgesia. The results suggest that there is a basal release of ET-1 from neurons that affect baseline pain thresholds as well as an additional release during persistent pain states that acts to suppress the pain. The involvement of neuronal ET-1 in stress-induced analgesia further suggests its role in endogenous pain inhibitory systems. To confirm that ET-1 is released in persistent pain states and to determine which part of the CNS is involved, we measured the concentrations of ET-1 before and after inducing peripheral inflammation in different parts of the CNS involved in endogenous pain inhibitory systems in normal mice. We found that ET-1 was increased in the hypothalamus while no significant increase was observed in the midbrain, medulla and spinal cord. The results of the present study suggest that neuronal ET-1 is involved in endogenous pain inhibitory control likely via pathways through the hypothalamus.

Acute Disease↗
PubMed2005

[Clinical experience of sivelestat sodium hydrate for severe reexpansion pulmonary edema; report of a case].

An 81-year-old man was referred to our hospital for the treatment for left spontaneous pneumothorax. A chest X-ray revealed a left-sided total pneumothorax and complete collapse of the lung. After intravenous administration of methylprednisolone, a 16 Fr chest tube was inserted, and drainage was started without negative pressure suction. Four hours after chest tube insertion, the patient's condition deteriorated. He complained severe cough and dyspnea, and pulse oximetry reading was 70%. A repeat chest X-ray demonstrated diffuse reexpansion pulmonary edema (RPE) on the left. After mechanical ventilation and intravenous infusion therapy with sivelestat sodium hydrate, methylprednisolone and ulinastatin were started, P(O2)/ Fi(O2) ratio improved rapidly. He was extubated on hospital day 6 and was discharged after pleurodesis for the pneumothorax. This case suggests that sivelestat sodium hydrate may be useful for the treatment for RPE.

Aged↗
PubMed2004

Isolation of eight novel Caenorhabditis elegans small RNAs.

Eight novel small RNAs that were encoded in the regions corresponding to the introns of protein-coding genes were isolated from Caenorhabditis elegans. Seven of them showed a typical snoRNA secondary structure: one C/D snoRNA and six H/ACA snoRNAs. The remaining one RNA did not show any homology to other RNAs in a database. Four of the seven isolated snoRNAs could form base pairings with parts of rRNAs, suggesting that they are potential pseudouridilation sites and methylation sites. The results of our study suggest that there are more as-yet-unidentified small ncRNAs of which genes are located in the intron regions of protein-coding genes in C. elegans.

Animals↗
PubMed2002

Randomized phase II study of biweekly CHOP and dose-escalated CHOP with prophylactic use of lenograstim (glycosylated G-CSF) in aggressive non-Hodgkin's lymphoma: Japan Clinical Oncology Group Study 9505.

BACKGROUND: CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) is accepted as the best available standard treatment for first-line chemotherapy in aggressive non-Hodgkin's lymphoma (NHL). However, the therapeutic efficacy of CHOP remains unsatisfactory, particularly in high-intermediate risk and high risk patients, and a new strategy is warranted in this patient population. The aim of the present study was to explore a suitable therapeutic-intensified regimen for the treatment of aggressive NHL. PATIENTS AND METHODS: Between May 1995 and July 1998, a total of 70 patients with high-intermediate risk or high risk aggressive NHL, according to the International Prognostic Index, were enrolled and randomly assigned to receive either eight cycles of standard CHOP (cyclophosphamide 750 mg/m(2), doxorubicin 50 mg/m(2), vincristine 1.4 mg/m(2) and prednisolone 100 mg for 5 days) every 2 weeks, or six cycles of dose-escalated CHOP (cyclophosphamide 1500 mg/m(2), doxorubicin 70 mg/m(2), vincristine 1.4 mg/m(2) and prednisolone 100 mg for 5 days) every 3 weeks. Lenograstim (glycosylated rHuG-CSF), at a dose of 2 micro g/kg/day s.c., was administered daily from day 3 until day 13 with biweekly CHOP and until day 20 with the dose-escalated CHOP. The primary endpoint was complete response rate. RESULTS: The complete response rate was 60% [21 of 35; 95% confidence interval (CI) 42% to 76%] with biweekly CHOP and 51% (18 of 35; 95% CI 34% to 69%) with dose-escalated CHOP. The major toxicity was grade 4 neutropenia and was more frequent in the dose-escalated CHOP arm (86%) than in the biweekly CHOP arm (50%). Grade 4 thrombocytopenia was also more frequent in the dose-escalated CHOP arm (20%) than the biweekly CHOP arm (3%). Non-hematological toxicities were acceptable in both arms. One treatment-related death (due to cardiac arrhythmia) was observed in a dose-escalated CHOP patient. Progression-free survival at 3 years was 43% (95% CI 27% to 59%) in the biweekly CHOP arm and 31% (95% CI 16% to 47%) in the dose-escalated CHOP arm. Although seven patients were deemed ineligible by central review of the pathological diagnosis, the results for both eligible and all enrolled patients were similar. CONCLUSIONS: Similar complete response rates and progression-free survival rates, but lower toxicity, indicated that biweekly CHOP was superior to dose-escalated CHOP in the treatment of aggressive NHL. Based on these results, the Lymphoma Study Group of the Japan Clinical Oncology Group is conducting a randomized phase III study comparing biweekly CHOP with standard CHOP in newly diagnosed patients with advanced-stage aggressive NHL.

Adult↗
PubMed2001

Calcineurin plays a critical role in the development of pressure overload-induced cardiac hypertrophy.

BACKGROUND: Although activation of the Ca(2+)-dependent phosphatase calcineurin has been reported to induce cardiomyocyte hypertrophy, whether calcineurin is involved in pressure overload-induced cardiac hypertrophy remains controversial. METHODS AND RESULTS: We examined in the present study the role of calcineurin in pressure overload-induced cardiac hypertrophy using transgenic mice that overexpress the dominant negative mutant of calcineurin specifically in the heart. There were no significant differences in body weight, blood pressure, heart rate, heart weight, and the cardiac calcineurin activity between the transgenic mice and their littermate wild-type mice at basal state. The activity of calcineurin was markedly increased by pressure overload produced by constriction of the abdominal aorta in the heart of wild-type mice but less increased in the heart of the transgenic mice. Pressure overload induced increases in heart weight, wall thickness of the left ventricle, and diameter of cardiomyocytes; reprogramming of expressions of immediate early response genes and fetal-type genes; activation of extracellular signal-regulated protein kinases; and fibrosis. All these hypertrophic responses were more prominent in the wild-type mice than in the transgenic mice. CONCLUSIONS: These results suggest that calcineurin plays a critical role in the development of pressure overload-induced cardiac hypertrophy.

Animals↗
PubMed2001

Isoproterenol activates extracellular signal-regulated protein kinases in cardiomyocytes through calcineurin.

BACKGROUND: Extracellular signal-regulated kinases (ERKs) and calcineurin have been reported to play important roles in the development of cardiac hypertrophy. We examined here the relation between calcineurin and ERKs in cardiomyocytes. METHODS AND RESULTS: Isoproterenol activated ERKs in cultured cardiomyocytes of neonatal rats, and the activation was abolished by chelation of extracellular Ca(2+) with EGTA, blockade of L-type Ca(2+) channels with nifedipine, or depletion of intracellular Ca(2+) stores with thapsigargin. Isoproterenol-induced activation of ERKs was also significantly suppressed by calcineurin inhibitors in cultured cardiomyocytes as well as in the hearts of mice. Isoproterenol failed to activate ERKs in either the cultured cardiomyocytes or the hearts of mice that overexpress the dominant negative mutant of calcineurin. Isoproterenol elevated intracellular Ca(2+) levels at both systolic and diastolic phases and dose-dependently activated calcineurin. Inhibition of calcineurin also attenuated isoproterenol-stimulated phosphorylation of Src, Shc, and Raf-1 kinase. The immunocytochemistry revealed that calcineurin was localized in the Z band, and isoproterenol induced translocation of calcineurin and ERKs into the nucleus. CONCLUSIONS: Calcineurin, which is activated by marked elevation of intracellular Ca(2+) levels by the Ca(2+)-induced Ca(2+) release mechanism, regulates isoproterenol-induced activation of ERKs in cardiomyocytes.

Adaptor Proteins, Signal Transducing↗
PubMed2001

gp130 plays a critical role in pressure overload-induced cardiac hypertrophy.

gp130, a common receptor for the interleukin 6 family, plays pivotal roles in growth and survival of cardiac myocytes. In the present study, we examined the role of gp130 in pressure overload-induced cardiac hypertrophy using transgenic (TG) mice, which express a dominant negative mutant of gp130 in the heart under the control of alpha myosin heavy chain promoter. TG mice were apparently healthy and fertile. There were no differences in body weight and heart weight between TG mice and littermate wild type (WT) mice. Pressure overload-induced increases in the heart weight/body weight ratio, ventricular wall thickness, and cross-sectional areas of cardiac myocytes were significantly smaller in TG mice than in WT mice. Northern blot analysis revealed that pressure overload-induced up-regulation of brain natriuretic factor gene and down-regulation of sarcoplasmic reticulum Ca(2+) ATPase 2 gene were attenuated in TG mice. Pressure overload activated ERKs and STAT3 in the heart of WT mice, whereas pressure overload-induced activation of STAT3, but not of ERKs, was suppressed in TG mice. These results suggest that gp130 plays a critical role in pressure overload-induced cardiac hypertrophy possibly through the STAT3 pathway.

Animals↗
PubMed2001

Expression of Fas ligand is an early event in colorectal carcinogenesis.

BACKGROUND AND OBJECTIVES: Fas ligand (FasL) is expressed in many cancers and plays an important role in establishing immunologically privileged environments that allow tumors to escape the host's immune surveillance. We investigate the expression of FasL in human colorectal cancer and colorectal adenoma and elucidate the relationship between FasL expression and the clinicopathological characteristics of colorectal cancers. METHODS: We examined 214 colorectal cancer specimens and 83 colorectal adenoma specimens. Expression of FasL was determined by immunohistochemical staining using a specific monoclonal antibody. We analyzed the relationship between the results of FasL expression and clinicopathological data statistically. RESULTS: FasL expression was detected in 173 (80.8%) of 214 colorectal carcinomas and 34 (40.9%) of 83 colorectal adenomas. The status of FasL expression in colorectal carcinoma was independent of clinicopathological features including tumor stage, histologic grade, lymphatic invasion, venous invasion, lymph node metastasis, liver metastasis, and Dukes stage. In colorectal adenoma, FasL expression was more frequently observed in high-grade atypia than in low-grade atypia (P = 0.05). CONCLUSIONS: FasL expression is commonly observed not only in cancer but also in highly dysplastic tissue. These observations suggest that FasL expression may be an important event in the transformation process leading to adenocarcinoma.

Adenocarcinoma↗
PubMed2001

Fragment-specific actions of parathyroid hormone in isolated perfused rat hearts.

Different regions within the parathyroid hormone (PTH) molecule are known to have different biological activities. In the heart, the physiological actions of the intact PTH molecule are known as positive chronotropy and coronary vasodilatation. However, it is unclear which region of the PTH exerts which physiological action in the heart. Therefore, to clarify this point, we examined the hemodynamic effect of intact PTH(1-84) and selected PTH analogs, namely, PTH(1-34), PTH(2-34), [Nle8, 18Tyr34]PTH(3-34), PTH(4-34), [Tyr34]PTH(7-34), and PTH(13-34) in isolated perfused rat hearts. Both PTH(1-84) and PTH(1-34) significantly increased heart rate and decreased coronary perfusion pressure. In contrast, neither PTH(2-34) nor [Nle8,18Tyr34]PTH(3-34) increased heart rate, but they did decrease coronary perfusion pressure. Peptides further truncated at the amino terminus, PTH(4-34), [Tyr34]PTH(7-34), and PTH(13-34), had no effect on hemodynamics. Furthermore, the protein kinase A inhibitor H89, but not the protein kinase C inhibitor H7, attenuated the hemodynamic effects of PTH(1-34) or PTH(2-34), while it prevented those of [Nle8,18Tyr34]PTH(3-34). These results clearly demonstrate that the first amino acid of PTH is essential for its chronotropic property whereas the first 3 amino acids of PTH are involved in its coronary vasodilatory action. Furthermore, protein kinase A, but not protein kinase C, appears to be involved in the chronotropic and coronary vasodilatory actions of PTH.

Animals↗
PubMed2001

Ca(2+)-sensitizing effect is involved in the positive inotropic effect of troglitazone.

1. Troglitazone, an insulin sensitizing agent, has a direct positive inotropic effect. However, the mechanism of this effect remains unclear. Thus, we examined the inotropic effect of troglitazone while focusing on intracellular Ca2+ handling. 2. Troglitazone significantly increased peak isovolumic left ventricular pressure (LVP(max)), peak rate of rise of LVP (dP/dt(max)), peak rate of fall of LVP (dP/dt(min)) in isolated rat hearts perfused at a constant coronary flow and heart rate. This inotropic effect of troglitazone was not inhibited by pretreatment with carbachol (muscarine receptor agonist), H89 (protein kinase A inhibitor), U73122 (phospholipase C inhibitor), H7 (protein kinase C inhibitor), verapamil (L-type Ca2+ channel antagonist), thapsigargin (Ca(2+)-adenosine triphosphatase inhibitor) or ryanodine (ryanodine receptor opener). 3. Radioimmunoassay showed that the cyclic adenosine monophosphate concentration in the left ventricle was not increased by troglitazone. 4. Whole-cell patch clamp analysis revealed that troglitazone had no effect on inward Ca2+ currents in cardiomyocytes. 5. In fura-2 loaded perfused rat hearts, troglitazone exerted its positive inotropic effect without increasing Ca2+ concentration. 6. These results suggest that neither the inward Ca2+ currents nor Ca2+ handling in the sarcoplasmic reticulum was involved in the inotropic effect of troglitazone. Furthermore, troglitazone exerted its positive inotropic effect without affecting the intracellular concentration of Ca2+. 7. In conclusion, the positive inotropic effect of troglitazone is mediated by a sensitization of Ca2+.

Animals↗