PubMed Health⌕ Search

Biomedical subjects

N Kawazoe

Publications and source records attributed to N Kawazoe.

At least 19 recordsLinked to original sources
PubMed2001

Peroxidase activity of in vitro-selected 2'-amino RNAs.

Peroxidase activities of RNAs containing 2'-amino groups, which were selected as aptamers binding to N-methylmesoporphyrin IX, were investigated. Some clones promoted the oxidation reaction of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) with hydrogen peroxide (H(2)O(2)) in the presence of iron(III)-protoporphyrin (hemin), whereas others did not. Each of them had a different substrate specificity. One of the active clones promoted the oxidation of o-dianisidine and beta-nicotinamide adenine dinucleotide reduced form (NADH) with H(2)O(2) 5 and 15 times faster than hemin only, respectively. On the other hand, one clone that was inactive on oxidation of ABTS exhibited the same level of activity on oxidation of o-dianisidine as that shown by the clone active on ABTS but no activity on NADH. By in vitro selection, we can produce various types of peroxidase-like non-natural RNAs.

Base Sequence↗
PubMed2001

Tumor metastasis suppressor nm23H1 regulates Rac1 GTPase by interaction with Tiam1.

The putative tumor metastasis suppressor nm23H1 was originally identified in murine melanomas by subtraction cloning. It displays nucleoside diphosphate kinase activity and regulates cellular events, including growth and development. Recently nm23H1 has been reported to also act as a GTPase-activating protein of the Ras-related GTPase Rad. We attempted to determine whether nm23H1 also regulates Rho-family GTPases. Although we were unable to detect a direct association between nm23H1 and Rho-family GTPases, nm23H1 was shown to be associated with a Rac1-specific nucleotide exchange factor, Tiam1, by interaction with its amino-terminal region in extracts from the cells expressing exogenous Tiam1 and from native tissue. Overexpression of nm23H1 inhibited the Tiam1-induced production of GTP-bound Rac1 and activation of c-Jun kinase. On the other hand, forced overexpression of the wild type, but not the kinase-inactivated mutant of nm23H1, converted the GDP-bound forms of Rac1, Cdc42, and RhoA to their GTP-bound forms in vitro by its nucleoside diphosphate kinase activity, but nm23H1 alone apparently did not produce the GTP-bound form of these GTPases in vivo. These results suggest that nm23H1 negatively regulates Tiam1 and inhibits Rac1 activation in vivo. Moreover, adhesion-stimulated membrane ruffles of Rat1 fibroblasts were reduced by overexpression of nm23H1. Based on these observations, we concluded that we had identified a function of nm23H1 as a regulator of Rac1 and that it may be related to the effect of nm23H1 as a tumor metastasis suppressor.

Cell Line↗
PubMed2001

In vitro selection of nonnatural ribozyme-catalyzing porphyrin metalation.

A new macromolecular catalyst, which is composed of nonnatural ribonucleotide, was synthesized by the in vitro selection (SELEX) method. A pool of RNAs consisting of random sequences was obtained by transcription from a pool of synthetic random-sequence DNAs in the presence of 2'-aminocytidine triphosphate (2'-amino-CTP) instead of CTP. The pool was incubated with N-methylmesoporphyrin-immobilized gel; bound nonnatural RNAs were then collected and amplified by reverse-transcription following the polymerase chain reaction. The amplified DNAs were again transcribed in the presence of 2'-amino-CTP and applied to the gel. This selection process was repeated 10 times. The selected RNAs were cloned and sequenced. The RNAs not only bound to the ligand, N-methylmesoporphyrin but also catalyzed the metalation reaction of porphyrin.

Base Sequence↗
PubMed2000

DNA aptamers that bind to chitin.

We have succeeded in the acquisition of DNA aptamers that recognize chitin using in vitro selection. The obtained DNA aptamers have the stem-loop or bulge loop structures with guanine rich loop clusters and the clockwise B-form stems.

Base Sequence↗
PubMed2000

In vitro selected oligonucleotides as receptors in binding assays.

This paper describes a new binding assay that uses oligodeoxyribonucleotides (DNAs) obtained by the in vitro selection method instead of antibodies. DNAs that specifically bound to a target molecule were selected, labeled with some probes, and then used to detect the target molecule by staining or competitive binding assay.

Base Sequence↗
PubMed2000

Neurally mediated syncope induced by lung cancer--a case report.

The authors present hemodynamic and autonomic features of recurrent and episodic neurally mediated syncope in a man with lung cancer involving afferent vagus. He revealed extreme hypotension with bradycardia occurring during sitting or standing. A head-up tilt test also induced syncope. However, syncope attacks no longer occurred 2 weeks after admission. Alternatively, the paralyses of the left recurrent laryngeal nerve and the left phrenic nerve developed. It is suggested that the lung cancer involved upper rootlets of the left vagus and caused transient hypersensitivity of baroreceptor function that resulted in neurally mediated syncope.

Carcinoma, Large Cell↗
PubMed2000

Adult reversible cardiomyopathy with pituitary adrenal insufficiency caused by empty sella--a case report.

The authors report a first case of reversible cardiomyopathy in an adult with adrenal insufficiency. A 62-year-old man was administered to hospital because of congestive heart failure. The electrocardiogram showed prolonged QT interval and negative T wave on the right precordial leads and frequent multifocal ventricular premature contractions. On the echocardiogram, the left ventricle was revealed to be diffusely hypokinetic with remarkable enlargement. 201Thallium single photon emission computed tomography (SPECT) revealed multiple flow defects in the left ventricular wall. He also had pituitary adrenal insufficiency secondary to an empty sella, which was diagnosed by hormonal studies and magnetic resonance images of the brain. After the replacement therapy with hydrocortisone, heart failure was sufficiently resolved. Abnormal flow defects in the myocardium on SPECT were also improved. To the authors' knowledge, adrenal insufficiency with cardiomyopathy has not been previously described in adult patients.

Adrenal Insufficiency↗
PubMed2000

Reoperation for graft failure of femoropopliteal bypass with externally supported knitted Dacron prosthesis.

BACKGROUND: Aggressive reoperation for failing or failed femoropopliteal (FP) bypass has been affirmative despite graft material. There has been no report regarding results of reoperation for FP bypass with externally supported knitted Dacron prosthesis (EXS). The aim of this study is to justify aggressive reoperation of FP bypass with EXS and to examine risk factors affecting the result of reoperation. METHODS: A retrospective review was performed on 204 patients undergoing 212 FP bypasses (with EXS between January 1982 and December 1997 and 34 FP EXSes of 32 patients underwent reoperation for graft failure until March 1998. The cumulative graft patency (GP) and limb salvage (LS) rate after first reoperation for 34 FP bypass EXS were calculated and the importance of each perioperative factor on GP or LS was estimated by uni- and multivariate analysis. RESULTS: Reoperated 34 FP EXSes included 12 failing and 22 failed grafts and 14 limbs with failed grafts underwent reoperation for limb salvage. The GP of 34 grafts and LS of 14 limbs rate were 58 and 67% at 2 years, respectively. Univariate analysis identified graft thrombosis (2 years GP; failing graft: failed graft=78: 48%) and continuance of smoking (2 years LS; smoker: non-smoker=43: 100%) as a significant risk factor of GP and IS, respectively, neither of which was significant by multivariate analysis. CONCLUSIONS: Early diagnosis and treatment, before graft thrombosis, can lead to superior durability of GP and discontinuance of smoking is important for LS.

Aged↗
PubMed1999

Tiam1 is involved in the regulation of bufalin-induced apoptosis in human leukemia cells.

Bufalin, a component of the Chinese medicine chan'su, induces apoptosis in various lines of human tumor cells, such as leukemia HL60 and U937 cells, by altering the expression of apoptosis-related genes, for example, bcl-2 and c-myc. In this study, we characterized a gene that is involved in bufalin-induced apoptosis by the differential display (DD) technique. The partial nucleotide sequence of one of the differentially expressed clones obtained after treatment with bufalin was identical to that of the human gene for Tiam1. When U937 cells were treated with 10(-7) M bufalin, expression of both Tiam1 mRNA and the protein was induced 1 h after the start of the treatment. The increase of Tiam1 mRNA was transient but the level of Tiam1 protein continued to increase at least for 6 h. In addition, the activities of Rac1 and p21-activated kinase (PAK) were also stimulated by bufalin treatment. To evaluate the role of Tiam1 in the apoptotic process, we examined the effects of the expression of sense and antisense RNA for Tiam1 in U937 cells. Apoptosis was strongly induced by bufalin in cells that expressed sense RNA for Tiam1 as compared to apoptosis in control cells treated with bufalin only. Cells expressing antisense RNA for Tiaml were significantly more resistant than the control bufalin-treated cells to induction of DNA fragmentation in response to bufalin. Moreover, sense transformants had elevated activities of PAK and c-Jun NH2-terminal kinase (JNK). These results suggest that Tiaml might play a critical role in bufalin-induced apoptosis through the activation of Rac1, PAK, and JNK pathway.

Antineoplastic Agents↗
PubMed1999

Extended in vitro selection for synthesis of novel molecular recognition oligonucleotide derivatives.

In vitro selection of RNA aptamer containing biotin-carrying nucleotide was carried out used for development of a new type of molecular sensor. Cytidine 5'-triphosphate (CTP) carrying biotinyl group at the N6-position was used in this technique. A pool of biotin-containing RNAs, which binds specifically to adenosine 5'-triphosphate (ATP), was obtained and used for competitive binding assay of ATP. The selected nonnatural RNA possesses many biotinyl groups to render it a high sensitivity toward ATP.

Adenosine Triphosphate↗
PubMed1999

Extended in vitro selection for synthesis of novel catalytic oligonucleotide derivatives.

A new catalyst, which is composed of nonnatural ribonucleotides, was synthesized by the in vitro selection method. Nonnatural RNAs that bound to N-methylmesoporphyrin were selected from a pool of random-sequence RNAs containing 2'-amino cytidine 5'-triphosphate (2'-amino CTP) instead of CTP. The selected RNAs not only bound to the ligand, N-methylmesoporphyrin (NMM), but also catalyzed metalation reaction of porphyrin.

Catalysis↗
PubMed1999

Induction of apoptosis by bufalin in human tumor cells is associated with a change of intracellular concentration of Na+ ions.

In an attempt to characterize the mechanisms that are operative at the early stages of the induction of apoptosis by bufalin, a component of the traditional Chinese medicine chan'su, we examined the effects of bufalin on plasma membrane potential, as determined by monitoring the uptake by cells of rhodamine 123. Bufalin induced apoptosis in human monocytic leukemia THP-1 cells, in human lymphoblastic leukemia MOLT-3 cells, and in human colon adenocarcinoma COLO320DM cells but not in normal human leukocytes, for example, polymorphonuclear cells and lymphocytes, and not in murine leukemia P388D1 and M1 cells. Treatment for 3 h with bufalin at 10(-6) M caused a decrease in the plasma membrane potential in several lines of human tumor cells but not in murine leukemia cells. No changes in mitochondrial membrane potential, as monitored with the fluorescent dye JC-1, and no release of cytochrome c were observed within at least 6 h after the start of treatment with bufalin. Moreover, overexpression of bcl-2 in human leukemia HL60 cells that had been transfected with cDNA for bcl-2 prevented bufalin-induced apoptosis but had no significant effect on the change in plasma membrane potential induced by bufalin. Since bufalin specifically inhibits the Na+,K(+)-ATPase of human but not murine tumor cells, and since this inhibition leads to a change in intracellular concentration of Na+ ions, our findings suggest that bufalin induces apoptosis in human tumor cells selectively via inhibition of the Na+,K(+)-ATPase, which acts upstream of the bcl-2 protein.

Animals↗
PubMed1999

[Patients with cardiomyopathy screened by an annual health check].

We identified 12 new cases of hypertrophic cardiomyopathy (HCM) and 3 new cases of dilated cardiomyopathy (DCM with echocardiography) in 72980 (aged 18-85 years, 43.1 +/- 14.1) industrial workers during an annual health check from April to October in 1996. Two of 3 patients with DCM were males, 21 and 25 years of age. No patients had symptoms. ST-T abnormalities by electrocardiography were found in 87% (13/15) of patients with cardiomyopathy and left ventricular hypertrophy (LVH) in 53% (8/15). Our findings suggest that echocardiography is important in mass screening for early detection of asymptomatic cardiomyopathy in middle-aged as well as young patients with ST-T abnormalities.

Adolescent↗
PubMed1998

Competitive binding assay for thyroxine using in vitro selected oligonucleotides.

A new binding assay that uses oligodeoxyribonucleotides (DNAs) obtained by the in vitro selection method, instead of antibodies, to bind to the target molecule, thyroxine (T4), is described. The DNAs which selectively bound to the T4 were selected, labeled with biotin or radioisotope, and then used to detection of T4 in the presence of liothyronine (T3), which has a chemical structure similar to that of T4.

Biosensing Techniques↗
PubMed1998

Fifteen-year experience in axillofemoral bypass with externally supported knitted Dacron prosthesis in a Japanese hospital.

BACKGROUND: Recently, several reports in the United States have demonstrated remarkable improvement in the patency of axillofemoral (AXF) bypass with an externally supported prosthesis. The purpose of this study was to review the prognoses regarding graft patency, limb salvage, and survival of patients who underwent AXF bypass grafting with an externally supported, knitted Dacron prosthesis (EXS) in a Japanese hospital and to analyze what factors affected the graft patency. METHODS: The clinical records of 81 patients with arteriosclerosis obliterans (ASO) who underwent 47 axillounifemoral bypasses and 34 axillobifemoral bypasses with EXS were retrospectively checked and, by uni- and multivariate analysis, perioperative factors were evaluated. RESULTS: The cumulative primary and secondary patency rates of AXF bypass grafts were 81% and 88%, 73% and 80%, and 70% and 77% at 3, 5, and 7 years, respectively, with no change thereafter. Limb salvage rate was 100%. The operative mortality was 3.7% and the survival rate was 63%, 41%, and 35% at 3, 5, and 7 years, respectively. The risk factors adversely affecting the patency were age (younger than 75 years), poor distal runoff, and preoperative leukocyte count (more than 8,000/microL) by univariate analysis, none of which were significant by stepwise multivariate analysis. CONCLUSIONS: AXF bypass using EXS was an acceptable procedure in ASO patients at high risk for conventional anatomic bypass or with limited life expectancy, and there was no significant risk factor that independently affected the patency.

Age Factors↗
PubMed1998

Circumferential spontaneous coronary artery dissection in an elderly man: a case report.

An 82-year-old man developed acute inferior myocardial infarction. Emergent coronary angiography demonstrated thrombotic occlusion in the right coronary artery. Intracoronary thrombolytic therapy was performed with successful recanalization. However, circumferential dissection with luminal stenosis was revealed at the point of thrombus formation. Repeat angiography 6 months later showed resolution of the dissection. This is the first description of circumferential spontaneous coronary artery dissection. In addition, the present patient is older than any previous patients.

Aged↗
PubMed1998

Para-anastomotic aneurysms: incidence, risk factors, treatment and prognosis.

BACKGROUND: The purpose of this retrospective study was to analyze the incidence, risk factors, treatment, and prognosis of para-anastomotic aneurysms. METHODS: During the period between January, 1980 and August, 1996, 511 patients underwent surgical operations for arterial diseases with grafts and were followed for more than 30 days (average: 3.5 years). The number of anastomoses was 1445 in all. Until October, 1996, 18 para-anastomotic aneurysms had been detected in 13 patients. By Kaplan-Meier's method, the incidence of para-anastomotic aneurysms at 5, 10, and 15 years was 0.8, 6.2, and 35.8%, respectively. Univariate analysis indicated that arteriosclerosis obliterans, hypertension, thromboendarterectomy and an anastomosis in the groin were significant risk factors, while stepwised multivariate analysis revealed only hypertension as significant. The mean interval from the primary operation to the diagnosis was 79 months. Ten aneurysms were operated and seven were produced by dehiscence of the anastomotic line, namety anastomotic aneurysms, and three were juxta-anastomotic aneurysms with intact anastomotic lines. Eight patients underwent resection or exclusion of the aneurysm and reconstruction with a new graft and two patients underwent a replacement of the aneurysmal autovein patch to a Dacron one and aneurysmorrhaphy of the parent aneurysmal artery. RESULTS: No recurrence has been detected. In eight patients who were followed conservatively, two died of rupture and renal failure following acute arterial occlusion. CONCLUSIONS: Since para-anastomotic aneurysms can lead to fatal complications, an enlarging or symptomatic aneurysm should be treated promptly.

Adult↗