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M Isogai

Publications and source records attributed to M Isogai.

87 records · Page 5Linked to original sources
PubMed1984

Neosurugatoxin, a specific antagonist of nicotinic acetylcholine receptors.

Neosurugatoxin (NSTX) (3 nM-30 nM), recently isolated from the Japanese ivory mollusc (Babylonia japonica) exerted a potent antinicotinic action in the isolated guinea pig ileum. Specific [3H]nicotine binding to rat forebrain membranes was saturable, reversible, and of high affinity. Nicotinic cholinergic agonists exhibited a markedly greater affinity for [3H]nicotine binding sites than a muscarinic agonist, oxotremorine. Although alpha-bungarotoxin had no effect on [3H]nicotine binding, low concentrations (1 nM-1 microM) of NSTX inhibited [3H]nicotine binding in the forebrain membranes and its IC50 value was 69 +/- 6 nM. On the other hand, NSTX did not affect muscarinic receptor binding in the brain. These data indicate that NSTX may be of appreciable interest as a neurotoxin with a selective affinity for ganglionic nicotinic receptors.

Animals↗
PubMed1983

Regional adaptation of muscarinic receptors and choline uptake in brain following repeated administration of diisopropylfluorophosphate and atropine.

The specific [3H]QNB binding and high-affinity uptake of [14C]choline in 8 brain regions (cerebral cortex, hippocampus, hypothalamus, thalamus, striatum, midbrain, cerebellum and brainstem) after repeated administration of DFP and atropine to guinea-pigs were simultaneously measured. Following repeated DFP administration, AChE was markedly depressed in each brain region. In these animals, there was a significant decrease in specific [3H]QNB binding in the cerebral cortex, hippocampus and striatum, whereas the [3H]QNB binding in the rest of brain regions was unchanged. Scatchard analysis revealed a 36% decrease in the Bmax value for the striatal [3H]QNB binding without a change in the Kd value, suggesting a change in the receptor density. In contrast, repeated atropine administration produced a significant enhancement in the [3H]QNB binding only in the hippocampus and striatum. The Bmax value in the striatum increased by 21% without a change in the Kd value. In addition to the receptor alteration, high affinity uptake of [14C]choline in the hippocampus and striatum was significantly decreased by DFP treatment, while that in the striatum increased by atropine treatment. Thus the present study has demonstrated that a prolonged activation and blockade of central muscarinic receptors resulted in specific adaptation in both the receptor density and ACh availability at the synapses in the cerebral cortex, hippocampus and striatum.

Acetylcholinesterase↗
PubMed1983

Correlation between cholinesterase inhibition and reduction in muscarinic receptors and choline uptake by repeated diisopropylfluorophosphate administration: antagonism by physostigmine and atropine.

Muscarinic receptors, [14C]choline uptake and acetylcholinesterase (AChE) activity in central and peripheral tissues of guinea-pigs treated repeatedly with diisopropylfluorophosphate (DFP) were simultaneously determined. After repeated DFP (1 mg/kg) administration, there was a significant decrease in specific [3H] quinuclidinyl benzilate binding only in the striatum, ileal longitudinal muscle and urinary bladder among various tissues examined. Scatchard analysis revealed that the administration of DFP at 0.5, 1 and 2 mg/kg which depressed the tissue AChE by 50 to 90%, caused a dose-dependent decrease (20-50%) in striatal and ileal [3H]quinuclidinyl benzilate binding sites without a change in the dissociation constant. The lower dose (0.2 mg/kg) of DFP depressed significantly the AChE in both tissues by 30% but failed to alter their [3H]quinuclidinyl benzilate binding sites. High affinity uptake of [14C]choline in the striatum and ileal longitudinal muscle was significantly decreased by repeated administration of DFP at 0.5 and 1 mg/kg but not 0.2 mg/kg. The DFP-induced loss of striatal and ileal muscarinic receptors was effectively antagonized by a concomitant administration of physostigmine (0.5 mg/kg) and atropine (5 mg/kg). Also, these drugs antagonized the DFP-induced decrease in the striatal [14C]choline uptake. Thus, the present study has demonstrated that repeated DFP administration causes a specific decrease in muscarinic receptors and [14C]choline uptake in the striatum and ileal longitudinal muscle of guinea pigs which is closely associated with a considerable (more than 50%) depression of the tissue AChE. In addition, these adaptive changes by DFP were effectively antagonized by physostigmine and atropine.

Acetylcholinesterase↗
PubMedDate not supplied

Supravesical hernia: CT diagnosis.

We report two cases of surgically proven supravesical hernia, one an internal supravesical hernia and the other an external supravesical hernia. Abdominal computed tomography showed the relation of the incarcerated intestine anterior to and compressing the urinary bladder. Although neither case was diagnosable preoperatively, we believe that the preoperative diagnosis of supravesical hernia by abdominal computed tomography is possible.

Aged↗
PubMedDate not supplied

Successful transcatheter embolization of a pancreaticoduodenal artery aneurysm in association with celiac axis occlusion: a case report.

We report a case of a pancreaticoduodenal artery (PDA) aneurysm in association with celiac axis occlusion. A 54 year-old female complaining of abrupt onset of abdominal pain was admitted to our hospital. On admission, abdominal CT examination revealed a hematoma in the retroperitoneal space. Selective superior mesenteric artery (SMA) angiography disclosed an aneurysm in the anterior inferior pancreaticoduodenal artery (AIPDA). The celiac axis was occluded and blood was flowing to the liver and spleen via the enlarged pancreaticoduodenal arcade from the SMA. Transcatheter embolization of the aneurysm was performed successfully. Up to 1996, there have been 37 reported cases of PDA aneurysm in association with celiac axis stenosis or occlusion, including this one. Transcatheter embolization was performed successfully in only 5 of these cases. The formation of this type of PDA aneurysm is thought to be a result of the increased blood flow in the pancreaticoduodenal arcade due to celiac axis stenosis or occlusion. The transcatheter embolization performed in our report produced a far greater blood flow, which may lead to further aneurysmal formation. Careful follow-up is therefore necessary.

Aneurysm↗
PubMedDate not supplied

Duplication of the gallbladder with advanced adenocarcinoma: diagnostic value of MRI and angiography.

We present a very rare case of duplicated gallbladder in which the accessory gallbladder was involved by advanced adenocarcinoma with stones. In this case, MRI was the most useful modality in revealing the cystic formation of the accessory gallbladder with packed stones beside the main gallbladder. Additionally, celiac angiography demonstrated the unusual form of the intrahepatic artery which enveloped the cystic tumor, that might be a diagnostic characteristic of accessory gallbladder.

Adenocarcinoma↗
PubMedDate not supplied

Change in chemosensitivity of DMBA-induced rat mammary tumor after oophorectomy.

BACKGROUND: A combination of chemotherapy and endocrine therapy is usually employed for the treatment of breast cancer, but the optimal order of this combination has not yet been verified. To determine the appropriate order of this combination, changes in chemosensitivity to anticancer agents after endocrine therapy were examined. MATERIALS AND METHODS: Rat mammary tumors induced by 7,12-dimethylbenz[alpha]-anthracene (DMBA) were used. Chemosensitivity tests were performed before and 3 weeks after bilateral oophorectomy. The MTT assay was used to test eight anticancer agents, and oophorectomy was performed as the endocrine therapy. RESULTS: DMBA-induced rat mammary tumors showed sensitivity to 4'-0-tetrahydropyranyl-doxorubicin, 5-fluorouracil, peplomycin, mitomycin C, and methotrexate. Chemosensitivity to these agents seemed to be somewhat reduced after oophorectomy compared with before the operation, but the difference was not significant. CONCLUSION: The influence of oophorectomy on chemosensitivity of DMBA-induced mammary tumor is thought to be minimal.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

A case of obstructive colitis caused by possible colostomy dysfunction.

A case of obstructive colitis caused by possible stricture of colostomy is herein reported. A 58 year old female with an obstructive sigmoid colon cancer underwent an emergency descending decompression colostomy. At laparotomy, the colon proximal to the carcinoma was markedly distended and the bowel wall was thin, but the serosa appeared normal. Postoperatively, however, abdominal pain and distension persisted and low grade fever developed. Diarrhea through the colostomy continued. Nine days after the initial surgery, she underwent a left hemicolectomy. An abnormally thickened segment was identified in the resected specimen; normal mucosa was lost and several pseudopolyps were scattered. Histopathological findings of the abnormal segment were consistent with obstructive colitis. A preserved segment of normal mucosa intervened between the site of colostomy and the abnormal segment of obstructive colitis. A possible stenosis of the colostomy was considered to have caused colostomy dysfunction and subsequent obstructive colitis. She was complicated with anastomotic leakage due to the diseased colon being used for anastomosis. Obstructive colitis should be kept in mind in patients with obstructive colonic carcinomas who complain of persistent abdominal pain, distension and diarrhea in the early postoperative period after colostomy.

Colitis↗