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Biomedical subjects

N Koizumi

Publications and source records attributed to N Koizumi.

At least 73 records · Page 4Linked to original sources
PubMed1999

[Mechanism of inhibitory effects of ethanol on gallbladder contraction: differences in cases of histamine- and acetylcholine-induced contraction].

We investigated the effects of different concentrations of ethanol on contraction of gallbladder isolated from guinea pig. Ethanol at 25 mM significantly inhibited the contraction induced by histamine, but not those by KCl and acetylcholine. A higher concentration (100 mM) of ethanol inhibited both histamine-, acetylcholine- and KCl- induced contractions. The inhibitory effect of the lower concentration (25 mM) of ethanol was not observed in the presence of verapamil, an antagonist of L-type Ca2+ channel or staurosporine, a selective inhibitor of protein kinase C. Verapamil and staurosporine significantly inhibited both histamine- and acetylcholine-induced contractile responses: the inhibitory effect was more potent for the histamine contraction. Our recent study has demonstrated that contraction caused by protein kinase C activation is completely dependent on Ca2+ influx through the L-type Ca2+ channel in gallbladder smooth muscle of guinea pig. Therefore, the difference in 25 mM ethanol effect on histamine- and acetylcholine-induced contractions may be due to different degree of involvement of protein kinase C activation in the agonist-induced contraction. On the other hands, the higher concentration (100 mM) of ethanol inhibits the common pathway of contraction in gallbladder smooth muscle cells.

Acetylcholine↗
PubMed1999

Surgical management of arteriosclerotic coronary artery aneurysm.

A 60-year-old man suffered antero-septal myocardial infarction at the age of 56. Coronary angiography demonstrated total occlusion of the left anterior descending artery and a large saccular aneurysm of the right coronary artery. Diffuse coronary ectasia was also shown in the right coronary artery adjacent to the aneurysm. Despite anticoagulant therapy, the aneurysm formed a thrombus and developed coronary artery stenosis distal to the aneurysm. Ligation of the aneurysm and in situ gastroepiploic artery grafting were performed. Sudden heart failure was developed during skin closure. As this condition was considered to be graft hypoperfusion, supplemental saphenous vein grafting was placed. Ligation is a simple, reliable technique to prevent future complications for a large saccular right coronary artery aneurysm, however, gastroepiploic artery might be an inappropriate bypass conduit for the ligated coronary artery with diffuse ectasia.

Arteries↗
PubMed1998

[Postoperative changes in the coagulation and fibrinolytic systems in endoluminal stent-graft treatment of thoracic aortic aneurysms].

We studied changes in blood coagulation and fibrinolytic system in 18 cases of thoracic aortic aneurysm and 5 cases of aortic dissection treated with stent grafts. The mean operation time was 259 +/- 67 minutes and the amount of blood loss during operation was 472 +/- 456 ml. Although blood transfusion of 220 +/- 360 ml was performed in 7 cases, 16 of 23 cases (70%) received no homologous blood transfusion. Consequently, the endoluminal stent graft treatment was minimally invasive compared with the conventional surgical procedure. On the 1st postoperative day, platelet counts and AT-III decreased and TAT increased. The promotion of blood coagulability was found in these patients on the 1st day after the operation. Changes in the fibrinolytic system were less marked than that in coagulation. These results suggest that the thrombosed aneurysm was excluded from systemic blood flow by the stent graft. There was no consumption coagulopathy in any case with aneurysm excluded by stent graft deployment. Stent-graft treatment for thoracic aortic aneurysm can be successfully performed without consumption coagulopathy when the aneurysm is completely excluded.

Aged↗
PubMed1998

[Clinical results of endovascular stent graft repair for fifty cases of thoracic aortic aneurysms].

Between February 1995 and December 1997, 50 cases (55 lesions) of thoracic aortic aneurysms including 20 cases of aortic dissections were treated with an endovascular technique using the stent grafts. All patients were treated in the operating room under general anesthesia and the stent grafts were implanted through 18 Fr. or 20 Fr. sheaths via femoral arteries under fluoroscopic guidance. The stent graft was composed of several units of self-expanding stainless-steel Z stents covered with an ultra-thin polyester fabric. Stent graft deployment was technically successful in 53 of 55 lesions (delivery success rate: 96.4%). Exclusion of the aneurysms and entry closing without endoleak were achieved within two weeks after the operation in 43 of 53 lesions (initial success rate: 81.1%). Endoleak was found in 10 lesions (minor endoleak: 8 and major endoleak: 2 lesions). Two patients died in the periopertive period of delivery failures as injury to external iliac artery and damage to the delivery sheath caused by tortuous and narrow access routes. Endovascular stent graft repair of thoracic aortic aneurysms is minimally invasive operation in comparison with conventional surgical graft replacement with extracorporeal circulation. These early results suggest that the stent graft repair is possibly safe and useful treatment for the patients of thoracic aortic aneurysms especially in high risk patients. However, careful long-term follow-up is necessary to prove the value and the effects of this endovascular treatment and improvement of the stent graft system and technical training of endovascular surgery for operators are required to reduce the delivery failure and to determine the stent graft repair is reliable treatment.

Adult↗
PubMed1998

[Prediction of spinal cord ischemia with a retrievable stent graft on endovascular treatment for a case of thoracic aortic aneurysm].

Multiple aortic aneurysms in Behçet's disease were repaired with transluminaly placed endovascular stent grafts. Before deploying the stent graft device for permanent implantation for the saccular aneurysm located in the descending thoracic aorta, from which feeding arteries for the spinal cord possibly branched, a retrievable stent graft was inserted and evoked spinal cord potential (ESP) were monitored in order to predict spinal cord ischemia. The original retrievable stent graft, constructed of a self-expandable Z-shaped stainless steel stent covered with e-PTFE, can be easily withdrawn into a 18 Fr. sheath after deployment. Blood flow into intercostal arteries branching from that part of the descending aorta where the permanent stent graft is planned to be implanted, is intercepted by the retrievable stent graft. A change of ESP during the temporary implantation of the device indicates that spinal cord ischemia would be caused by permanent implantation of the stent graft. In this case, no change of ESP was observed and the patient showed no postoperative paraplegia. The retrievable stent graft was useful for prediction of spinal cord ischemia before endoluminal stent graft repair of the descending aortic aneurysm. However, the device is not flexible enough to fit a severely tortuous aorta, therefore we are obliged to select patients to some extent. Further improvement of the device is required to make prediction of spinal cord ischemia with the retrievable stent graft possible in all cases.

Aortic Aneurysm, Thoracic↗
PubMed1998

Preliminary report on prediction of spinal cord ischemia in endovascular stent graft repair of thoracic aortic aneurysm by retrievable stent graft.

OBJECTIVE: To predict spinal cord ischemia after endovascular stent graft repair of descending thoracic aortic aneurysms, temporary interruption of the intercostal arteries (including the aneurysm) was performed by placement of a novel retrievable stent graft (Retriever) in the aorta under evoked spinal cord potential monitoring. METHODS: From February 1995 to October 1997, endovascular stent graft repair of descending thoracic aortic aneurysms was performed in 49 patients after informed consent was obtained. In 16 patients with aneurysms located in the middle and distal segment of the descending aorta, the Retriever was placed temporarily before stent graft deployment. The Retriever consisted of two units of self-expanding zigzag stents connected in tandem with stainless steel struts. Each strut was collected in a bundle fixed to a pushing rod, and the stent framework was lined with an expanded polytetrafluoroethylene sheet. The Retriever was delivered beyond the aneurysm through a sheath and was retracted into the sheath 20 minutes later. A stent graft for permanent use was deployed in patients whose predeployment test results with the Retriever were favorable. Evoked spinal cord potential was monitored throughout placement of the Retriever and stent grafting until the next day. RESULTS: The Retriever was placed in 17 aneurysms in 16 patients. There were no changes in amplitude or latency of evoked spinal cord potential records obtained before or during Retriever placement. After withdrawal of the Retriever, all aneurysms were excluded from circulation immediately after permanent stent grafting. There were no changes in evoked spinal cord potential, nor were neurologic deficits seen after stent graft deployment in any patient. CONCLUSIONS: These results suggest that predeployment testing with the Retriever under evoked spinal cord potential monitoring is promising as a predictor of spinal cord ischemia in candidates for stent graft repair of thoracic aortic aneurysms.

Aged↗
PubMed1998

Serum levels of interleukin-6, alpha1-acid glycoprotein, and corticosterone in two-week-old chickens inoculated with Escherichia coli lipopolysaccharide.

The concentration of interleukin-6 (IL-6), alpha1-acid glycoprotein (alpha1-AG), and corticosterone (CORT) was investigated chronologically (0 h to 14 d) in the sera of 2-wk-old specific-pathogen-free chicks inoculated with Escherichia coli lipopolysaccharide (LPS). In the LPS group the IL-6 level was elevated from 1 h to 2 d and was the highest at 3 h. From 4 to 14 d the IL-6 level was low in the LPS group. In the PBS group, IL-6 was not detected except a mild increase from 1 h to 6 h. In the LPS group, the alpha1-AG level increased from 6 h to 4 d, and the peak was 2 d. In the PBS group the alpha1-AG level was always low. The CORT level in the LPS group was higher than that of PBS group at 1 h. This study suggests that E. coli LPS may elevate serum IL-6 and CORT, and that IL-6 and CORT may increase the alpha1-AG level in the chicks.

Animals↗
PubMed1998

[Screening test by statistically reducing the number of the State-Trait Anxiety Inventory (STAI) items].

The purpose of the study is to find a method of mental examination which can be simply performed concurrently with physical examination during a regular check-up. On a regular check-up, the state-trait anxiety inventor (STAI) was administered to 264 construction workmen engaged in reconstruction work for the Hanshin Awaji Great Earthquake. Data on a total of 40 STAI items, i.e., 20 state anxiety (A-State) items and 20 trait anxiety (A-Trait) items were subjected to multiple regression analysis and five items were extracted from A-State and five from A-Trait items as a practical tool for a simple screening test. The contribution rates of the respective five items for the total score were 90.0% for A-State and 88.5% for T-State. The correlation coefficients, r, between predicted and observed values were 0.949 (p < 0.01) for A-State and 0.940 (p < 0.01) for A-Trait. Because of certain degrees of validity and reliability of each five-item system, it is considered that this method is useful as a simple screening test to roughly grasp the mental health of subjects and can be utilized for mental health care at offices.

Adult↗
PubMed1998

Model of emotional stress in rats.

A new experimental rat model for suppression of release of arginine vasopressin (AVP) was evaluated. Release of AVP is potentiated by physiologic stimuli, but is suppressed by emotional stress. Rats were exposed to the aggressive behavior of other rats injected with 6-hydroxydopamine hydrochloride (6-OHDA) in both lateral ventricles and subjected to a pain stimulus applied to the tail. To ascertain whether emotional stress is induced by use of this method, plasma corticosterone, glucose, and AVP concentrations were measured in the stressed group of rats (n = 8) placed near a group of aggressive (fighting) rats. Characteristic changes in behavior, significant increases in plasma corticosterone and glucose values, and lack of increase in plasma AVP concentration in stressed rats confirmed that they experienced emotional stress. This new model meets the experimental requirements for suppression of AVP release in rats.

Aggression↗
PubMed1997

Lipopolysaccharide-binding proteins and their involvement in the bacterial clearance from the hemolymph of the silkworm Bombyx mori.

Proteins having the ability to bind to Escherichia coli K12W3110 (rough (R) mutant) were isolated and purified by affinity precipitation from the larval hemolymph of the silkworm Bombyx mori. These proteins were found to consist of two components with molecular masses of 43 kDa and 40 kDa by SDS/PAGE. They bound to all E. coli R mutants (Ra, Rb1, Rc, Rd1 and Re) and Salmonella minnesota R mutants. However, they did not bind to smooth types of the above bacteria. They bound to both lipopolysaccharide(LPS)-coated and lipid-A-coated microtiter plates and have similar dissociation constants for LPS and lipid A. This indicates that the binding proteins recognize the lipid A portion of LPS and thus, we have named these proteins BmLBP (B. mori LPS-binding proteins). We also found that BmLBP participated in the clearance of E. coli cells injected into the body cavity of the silkworm.

Acute-Phase Proteins↗
PubMed1997

Blood sampling technique for measurement of plasma arginine vasopressin concentration in conscious and unrestrained rats.

A new technique for collecting blood from conscious and unrestrained rats is reported. Plasma arginine vasopressin (AVP) concentration has been known to be influenced by various procedures used for blood collection (e.g., manual contact and anesthesia). In the study reported here, the improvement of the routine jugular vein cannula method was undertaken by extending the connection tubing to allow use of a swivel mechanism. Plasma AVP, glucose, and corticosterone concentrations in virgin rats were measured in blood samples collected by use of the new method and of two generally accepted methods (decapitation and routine jugular vein cannula methods). All values of the three parameters obtained were the lowest when the new method was used, suggesting that this new swivel method induced the least stress in the rats.

Animals↗
PubMed1997

[Stent graft treatment for two cases of DeBakey IIIb dissecting aortic aneurysm].

Two patients with DeBakey IIIb dissecting aortic aneurysms were treated with transluminally placed endovascular stent grafts. Surgery was required for both patients because the false lumens were not thrombosed for several months. Stent graft devices composed of several units of self-expandable Z stents covered with ultra-thin woven Dacron were inserted through 18 Fr sheathes via femoral arteries. The stent grafts were deployed successfully and blood flow into the false lumens was reduced immediately and finally thrombosed without blood leakage from the entries. The endoluminal stent graft treatment is minimally invasive operation in comparison with former surgical operations, and is useful for aortic aneurysms especially in high risk patients. However, improvement of the stent graft devices, including the delivery systems such as the dilator, sheath and pushing rod, which are incomplete, and developing better devices, is required to reduce delivery failure and to make the stent graft treatment more reliable.

Aged↗
PubMed1997

[CT-guided lung needle biopsy using a new supporting implement].

We contrived a new supporting implement to increase the hit rate of CT-guided needle biopsy (CTNB) for localized pulmonary lesions. Using this implement, twenty-two CTNB examinations for localized pulmonary lesions were performed. In 21 out of the 22 examinations (95%), the lesions were hit, and specimens appropriate for cytological or histological diagnosis were obtained. The course of needle insertion, which was difficult to define in the past, has become to be easier and more precise with this method. Using this new implement, CTNB is now applicable to smaller and deeper lesions.

Adult↗
PubMed1996

Isolation and responses to stress of a gene that encodes a luminal binding protein in Arabidopsis thaliana.

A cDNA encoding a luminal binding protein (BiP) was isolated from Arabidopsis thaliana. In Arabidopsis seedlings, accumulation of transcripts for BiP was induced not only by inhibition of the N-glycosylation of proteins by tunicamycin but also by inhibition of the processing of N-linked glycans by castanospermine. Heat-shock stress also induced accumulation of the transcripts in Arabidopsis.

Amino Acid Sequence↗
PubMed1996

Antiandrogen. IV. C-17 spiro 2-oxasteroids.

The preparation of 6- and/or 7-substituted 3-oxo-2-oxasteroids having a spirotetrahydrofuran ring at the 17-position is described. These compounds showed high antiandrogenic potency in the castrated male rat.

Androgen Antagonists↗
PubMed1996

Antiandrogen. III. 11-oxapregnane steroids.

11-Oxachlormadinone acetate (17-acetoxy-6-chloro-11-oxapregna-4,6-diene-3,20-dione) and 2,11-dioxachlormadinone acetate (17-acetoxy-6-chloro-2,11-dioxapregna-4,6-diene-3,20-dione) were prepared as potential antiandrogenic agents. The effect of the latter compound on antiandrogenic activity when tested in the castrated rat was shown to be more potent than that of the parent compound, chlormadinone acetate.

Androgen Antagonists↗