Takeshi Ohkubo

Nitric Oxide Production during Cerebral Ischemia and Reperfusion in eNOS- and nNOS-Knockout Mice

The purpose of this study was to clarify the kinetics of nitric oxide (NO) induced by either endothelial NO synthase (eNOS) or neuronal NO synthase (nNOS) after transient global forebrain ischemia. We investigated NO production and ischemic changes to hippocampal CA1 neurons in eNOS knockout (-/-) mice and nNOS (-/-) mice during cerebral ischemia and reperfusion. NO production was continuously monitored by in vivo microdialysis. Global forebrain ischemia was produced by occlusion of both common carotid arteries for 10 minutes. Levels of nitrite (NO(2)(-)) and nitrate (NO(3)(-)), as NO metabolites, in dialysate were determined using the Griess reaction. Two hours after the start of reperfusion, animals were perfused with 4% paraformaldehyde. Hippocampal CA1 neurons were divided into three phases (severely ischemic, moderately ischemic, surviving), and the ratio of surviving neurons to degenerated neurons was calculated as the survival rate. The relative cerebral blood flow (rCBF) was significantly higher in nNOS (-/-) mice than in control mice after reperfusion. Levels of NO(3)(-) were significantly lower in eNOS (-/-) mice and nNOS (-/-) mice than in control mice during ischemia and reperfusion. NO(3)(-) levels were significantly lower in nNOS (-/-) mice than in eNOS (-/-) mice after the start of reperfusion. Survival rate tended to be higher in nNOS (-/-) mice than in control mice, but not significantly. These in vivo data suggest that NO production in the striatum after reperfusion is closely related to activities of both nNOS and eNOS, and is mainly related to nNOS following reperfusion.

Carcinosarcoma of the rectosigmoid colon: Report of a case

We report an unusual case of carcinosarcoma of the colon. An 80-year-old woman was admitted to our hospital with lower abdominal pain. Computed tomography showed a large pelvic mass, 18 cm in maximal diameter, and barium enema and colonoscopy both showed a type-2 tumor in the sigmoid colon. We performed Hartmanns procedure with resection of the ileocolic segment. Immunohistochemical stains of the resected specimen revealed that most of the tumor consisted of spindle cell sarcoma with neural and muscle differentiation, while only the superficial area of an ulcerated lesion contained adenocarcinoma positive for carcinoembryonic antigen. The patient died of a fast-growing recurrent pelvic tumor 6 months postoperatively. Our experience of this case and our review of eight other cases in the English literature indicate that wide resection provides the best chance of cure, but careful postoperative follow-up is essential.

Regulation by midbrain raphe nuclei and locus ceruleus on cerebral vasomotor responses

It has been suggested that midbrain raphe nuclei have important roles in cerebral circulation and metabolism [1-3] by sending serotonergic fibers to both the large and small vessels of the brain [4,5] as well as to the locus ceruleus [6,7], which is the center of the adrenergic system. However, few studies [8,9] have been reported with regard to the functional significance of the serotonergic system in cerebral vasomotor responses to changes in arterial CO 2 tension (PaCOp. Moreover, no study was undertaken regarding the cerebral vasomotor responses to changes in perfusion pressure. The focus of the present study was directed towards the roles of these nuclei in the cerebral vasomotor responses to changes in cerebral perfusion pressure and PaCOz.

Effect of chronic lesion in lower pontine raphe nuclei on cerebral hemodynamics and its vasomotor responses.

橋下部縫線核 (橋縫線核・大縫線核) 破壊慢性モデルの, 脳循環動態に対する影響をサルを用いて検討した.破壊群8頭と刺入のみの非破壊群6頭を作成し, 1週間後に電磁流量計を用いて内頸動脈血流を測定した.脳循環化学調節能はChemical Vasomotor Index (%CVI) を, 脳循環自動調節能はAutoregulation Index (%AI) を, 脳代謝は脳酸素消費量を指標とした.1) 血圧・脈拍は両群間に差を認めなかった.2) 内頸動脈血流は破壊群と非破壊群, 破壊群の左右の比較で差を認めなかった.3) 脳酸素消費量は破壊群が非破壊群との比較で有意な増加 (p<0.05) を示した.4) CO2吸入負荷時の%CVIは, 破壊群の左側が非破壊群に比し高値傾向, 過換気負荷では壊破壊群の右側が非破群に比し有意な低下 (p<0.02), 左側も低下傾向を示した.5) 脱血・血液注入負荷時の%AIは, 破壊群と非破壊群, 破壊群の左右の比較で差がなかった.以上の成績は, 橋下部縫線核群が脳代謝および脳循環化学調節に関与することを示唆する.

Which has a More Significant Role, Locus Ceruleus or Nucleus Tractus Solitarii, in Hemispheric Vasomotor Responses ?

Locus ceruleus (LC) and nucleus tractus solitarii (NTS) are important brain stem nuclei in the regulation of cerebrovascular tone. Their functional significance in regulation of vasomotor responses has not tobe completedly elucidated. The aim of the present study was to investigate which nucleus had more important roles in the hemispheric vasomotor responses.