Biomedical subjects

Shusaku Hayashi

Publications and source records attributed to Shusaku Hayashi.

6 recordsLinked to original sources

PubMed2006

Healing impairment effect of cyclooxygenase inhibitors on dextran sulfate sodium-induced colitis in rats.

We examined the effects of various cyclooxygenase (COX) inhibitors on the healing of colonic lesions induced by dextran sulfate sodium (DSS) in the rat. Colonic lesions were induced by 2.5% DSS in the drinking water for 7 days, and then the animals were fed with tap water for subsequent 7 days. Indomethacin (a nonselective COX inhibitor), SC-560 (a selective COX-1 inhibitor), or rofecoxib (a selective COX-2 inhibitor) was given orally twice daily after termination of the DSS treatment. DSS treatment caused severe colonic lesions with a decrease in body weight gain and colon length as well as an increase in myeloperoxidase activity and thiobarbituric acid reactant levels. The severity of colitis gradually reduced, with an improvement of morphological and histological alterations. Daily administration of indomethacin and rofecoxib significantly delayed the healing of colitis with deleterious influences on histological restitution as well as mucosal inflammation, while SC-560 had no effect. Although COX-1 mRNA was expressed in the colon without much alteration during the test period, the expression of COX-2 was upregulated with a peak on day 3 and decreased thereafter. The mucosal prostaglandin E2 content in the colon showed a biphasic change, in parallel with that of the COX-2 expression. The increased prostaglandin E2 production in the injured mucosa was attenuated by indomethacin and rofecoxib, but not by SC-560. These results suggest that endogenous prostaglandins produced by COX-2 play an important role in the healing of DSS-induced colonic lesions. Caution should be paid to the use of selective COX-2 inhibitors as well as nonsteroidal anti-inflammatory drugs in patients with colitis.

Animals↗

PubMed2006

Post-ischemic hypothermia reduced IL-18 expression and suppressed microglial activation in the immature brain.

Inflammation is an important factor for hypoxia-ischemia (HI) brain injury. Interleukin (IL)-18 is a proinflammatory cytokine which may be a contributor to injury in the immature brain after HI. To investigate the effects of post-HI hypothermia on IL-18 in the developing brain, 7-day-old rats were subjected to left carotid artery ligation followed by 8% oxygen for 60 min and divided into a hypothermia group (rectal temperature 32 degrees C for 24 h) and a normothermia group (36 degrees C for 24 h). The IL-18 mRNA was analyzed with real-time RT-PCR, and the protein level was analyzed by Western blot, and the location and source of IL-18 were assessed by immunohistochemistry. The significant increase of the IL-18 mRNA was observed in the ipsilateral hemispheres of the normothermia group at 24 h and 72 h after HI compared with controls, but the level in the ipsilateral hemispheres of the hypothermia group was significantly reduced at both time points, compared with the normothermia group, respectively. The IL-18 protein level in the ipsilateral hemispheres of the normothermia group significantly increased at 72 h after HI compared with controls, however, the protein level of the hypothermia group was significantly decreased, compared with the normothermia group. IL-18-positive cells were observed throughout the entire cortex, corpus callosum (CC) and striatum in the ipsilateral hemispheres of normothermia group at 72 h after HI, however, little positive cells were observed in the hypothermia group. Double labeling immunostaining found that most of the IL-18-positive cells were colocalized with lectin, which is a marker of microglia. The number of ameboid microglia (AM) in the normothermia group was significantly increased in cortex and CC, compared with the number in controls, but there were very few ramified microglia (RM) in these areas. In contrast, the number of AM in the hypothermia group was significantly decreased in cortex and CC, compared with the number in the normothermia group, and there were no significant differences in the number of AM and RM between the hypothermia group and controls. In conclusion, we found that IL-18 mRNA and the protein level were attenuated by post-HI hypothermia and that post-HI hypothermia may decrease microglia activation in the developing brain.

Animals↗

PubMed2006

A decrease of cell proliferation by hypothermia in the hippocampus of the neonatal rat.

Hypothermia is a potential therapy for cerebral hypoxic ischemic injury of not only adults but also neonates. However, the side effects of hypothermia in the developing brain, where a massive amount of neurogenesis occurs, remain unclear. We investigated the proliferation of neural progenitor cells by systemic application of the thymidine analog 5-bromodeoxyuridine (BrdU) in neonatal rats in a severe hypothermic environment. The rat pups were divided into two groups, a hypothermia group (30 degrees C: n=10) and a normothermia group (37 degrees C: n=10). After the pups were placed for 21 h in each environment, 100 mg/kg/day of BrdU was injected intraperitoneally to label dividing cells, and then the pups were sacrificed at 24 h. We examined the number of BrdU-labeled cells in the subventricular zone of the periventricle and the subgranular zone of the dentate gyrus. In the hypothermic environment, BrdU-labeled cells significantly decreased in number in the dentate gyrus, but not in the periventricular region. Thus, the severe hypothermic environment induced a decrease of neurogenesis in the neonatal rat. These observations are noteworthy regarding clinical hypothermia therapy following cerebral hypoxic ischemic injury during the perinatal period.

Aging↗

PubMed2006

The effects of repeated corticosteroid administration on the neurogenesis in the neonatal rat.

OBJECTIVE: The purpose of this study is to clarify the effects on the brain including neurogenesis pretreated with repeated doses of dexamethasone in the neonatal rat. STUDY DESIGN: The 4-day-old Sprague Dawley rats were pretreated with 4 different regimens, namely, single administration of dexamethasone, 2-dose administration, 3-dose administration, and saline administration as a control. Concurrently, bromodeoxyuridine (BrdU), which was incorporated into the dividing cells, was administered. We examined body weight, brain weight, and the number of BrdU-labeled cells in the subventricular zone (SVZ), the subgranular zone (SGZ), and the cortex. RESULTS: Both the body and brain weight of the rats pretreated with dexamethasone were significantly decreased compared with those given saline. Quantitative analysis of BrdU-labeled cells revealed the significant dose-dependent decreases in the SVZ, the SGZ, and the cortex with the dexamethasone treatment. CONCLUSION: We concluded that the decreases in neurogenesis caused by repeated antenatal corticosteroid therapy might result in the adverse effects on the size of the head at birth.

Aging↗

PubMed2006

Prospective study of non-closure or closure of the peritoneum at cesarean delivery in 124 women: Impact of prior peritoneal closure at primary cesarean on the interval time between first cesarean section and the next pregnancy and significant adhesion at second cesarean.

AIM: The aim of this study was to evaluate the effect of non-closure of the peritoneum at cesarean delivery on postoperative complications and the interval time to the next pregnancy, and to investigate the incidence of adhesion following cesarean and the association between adhesion formation and peritoneal closure. METHODS: One hundred and twenty four women scheduled for cesarean section were randomized to either closure of both the visceral and parietal peritoneum (C-group, n = 70) or non-closure (NC-group, n = 54). At repeated cesarean, the levels and extent of adhesion, operating time, and any complications were examined. RESULTS: There was no difference in the incidence of postoperative complications at the first cesarean section. The operating time of the C-group was significantly longer than that of the NC-group. The frequency of analgesic use was significantly higher in the C-group. The time interval from cesarean section to the next pregnancy in the NC-group was significantly shorter than that in the C-group. There are no significant differences between the rates of complications in the C-group and the NC-group at repeated cesarean. The incidence of adhesion in the C-group was significantly higher than that in the NC-group (P < 0.05). The mean total operating time and the mean interval time for skin incision to delivery in the C-group were significantly longer than those in the NC-group (P < 0.05 and P < 0.001, respectively) at repeated cesarean section. CONCLUSIONS: Non-closure of the peritoneum at cesarean delivery appears to have no adverse effect on postoperative recovery, it also decreases the number of analgesic doses and shortens the operating time and may be more desirable in achieving a next pregnancy. The present study demonstrated that surgical peritoneal closure resulted in more advanced adhesion formation. The practice of non-closure of the peritoneum should be performed at cesarean.

Adult↗

PubMed2004

Expression of fractalkine in the Fallopian tube and of CX3CR1 in sperm.

BACKGROUND: Fractalkine is a CX(3)C chemokine that has chemoattractant activity for T cells, monocytes and natural killer (NK) cells. The objective of this study was 2-fold: to evaluate (i) the presence of fractalkine in the Fallopian tube and (ii) the existence of CX(3)CR1 (fractalkine receptor) in ejaculated sperm. METHODS AND RESULTS: Western blot analysis revealed that fractalkine protein was detected as a 95 kDa band in the isthmus, the ampulla and the infundibulum of the Fallopian tube. Immunohistochemistry revealed positive staining of epithelial cells in the Fallopian tube. RT-PCR demonstrated that fractalkine transcripts were expressed in all parts of the Fallopian tube. RT-PCR also revealed that CX(3)CR1-positive cells were present in the Fallopian tube. CX(3)CR1-positive cells were present in the stroma of the Fallopian tube. The villi of the ciliated cells were positively stained. To determine the function of fractalkine in the Fallopian tube, we examined whether CX(3)CR1 was present in ejaculated sperm. RT-PCR demonstrated that CX(3)CR1 transcripts were expressed in the ejaculated sperm. Immunohistochemistry demonstrated positive staining of the tail of the spermatozoa. CONCLUSIONS: The present findings suggest that fractalkine in the Fallopian tube contributes to the immunodefence mechanism during fertilization and to the sperm motion in the oviduct.

Adult↗