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N Ohtani

Publications and source records attributed to N Ohtani.

At least 19 recordsLinked to original sources
PubMed2006

Epigenetic abnormalities in cutaneous squamous cell carcinomas: frequent inactivation of the RB1/p16 and p53 pathways.

BACKGROUND: Aberrant methylation of CpG islands in the promoter regions of cancer-related genes has been demonstrated in many human tumours. However, the methylation profile of these regions in cutaneous squamous cell carcinomas (SCCs) has not been well studied. OBJECTIVES: To examine epigenetic abnormalities of a wide range of cancer-related genes in SCCs. METHODS: We investigated the methylation status of 11 candidate cancer-related genes (CDH1, p16(INK4a), p14(ARF), DAPK1, MGMT, RB1, RASSF1, p15(INK4b), PTEN, PRDM2 and p53) in 20 cases of SCC by methylation-specific polymerase chain reaction, and comparatively examined the protein production of E-cadherin (CDH1), p16, RB1, p14, BMI1 and cyclin A by immunohistochemical analysis. RESULTS: The frequency of cancer-related gene methylation in SCCs was: CDH1 (95%), p16 (20%), p14 (15%), DAPK1 (15%), MGMT (15%), RB1 (5%), RASSF1 (5%), p15 (0%), PTEN (0%), PRDM2 (0%) and p53 (0%). Almost all cases with hypermethylation of CDH1, p16, RB1 and p14 showed no obvious production of each protein, suggesting that promoter hypermethylation of these genes contributes to the loss of protein production. The results of methylation analysis, in combination with the results of our previous mutation analysis of CDKN2A locus and p53, revealed that 70% of SCCs have alterations in the RB1/p16 or p53 pathway. CONCLUSIONS: Our findings indicate that the promoter hypermethylation of cancer-related genes, especially CDH1, is frequently shown in SCCs, and dysregulation of the RB1/p16 and/or p53 pathway through either genetic or epigenetic mechanisms, except for epigenetic abnormalities of p53 itself, should contribute to the carcinogenesis of SCCs.

Aged↗
PubMed2001

Opposing effects of Ets and Id proteins on p16INK4a expression during cellular senescence.

The p16INK4a cyclin-dependent kinase inhibitor is implicated in replicative senescence, the state of permanent growth arrest provoked by cumulative cell divisions or as a response to constitutive Ras-Raf-MEK signalling in somatic cells. Some contribution to senescence presumably underlies the importance of p16INK4a as a tumour suppressor but the mechanisms regulating its expression in these different contexts remain unknown. Here we demonstrate a role for the Ets1 and Ets2 transcription factors based on their ability to activate the p16INK4a promoter through an ETS-binding site and their patterns of expression during the lifespan of human diploid fibroblasts. The induction of p16INK4a by Ets2, which is abundant in young human diploid fibroblasts, is potentiated by signalling through the Ras-Raf-MEK kinase cascade and inhibited by a direct interaction with the helix-loop-helix protein Id1 (ref. 11). In senescent cells, where the Ets2 levels and MEK signalling decline, the marked increase in p16INK4a expression is consistent with the reciprocal reduction of Id1 and accumulation of Ets1.

Animals↗
PubMed2001

Involvement of the Oct-1 regulatory element of the gadd45 promoter in the p53-independent response to ultraviolet irradiation.

The gadd45 gene, a growth arrest and DNA damage (gadd)-induced gene, is transcriptionally activated by UV irradiation through two distinct pathways. One requires the sequence-specific binding of the p53 tumor suppressor protein to a responsive element within the third intron of the gadd45 gene, and the other is p53-independent activation of the gadd45 promoter region, although the UV-response element that mediates this has yet to be defined. To investigate the sequences involved in induction of gadd45 by UV irradiation in a p53-independent pathway, we performed mutation analyses of the human gadd45 promoter fused to the luciferase reporter gene in cell lines in which p53 was inactivated. We found that the UV-responsive element was involved in the Oct-1 binding site at -99 bp relative to the transcription start site. Electrophoretic mobility shift assays showed that Oct-1, a transcription factor, bound this element on the gadd45 gene, although the intensity and mobility pattern of the retarded bands were not altered by UV irradiation. These results suggest that the Oct-1 regulatory element might be one of the essential elements involved in the activation of the gadd45 promoter by UV irradiation in a p53-independent pathway.

Cell Division↗
PubMed2001

Evaluation of an internal thoracic artery as a coronary artery bypass graft by intercostal duplex scanning ultrasonography.

OBJECTIVES: Although angiography is often used to determine whether the internal thoracic artery is appropriate as a coronary bypass graft, but use of duplex scanning ultrasonography for this purpose is not yet widespread. METHODS: The internal diameter and flow of the internal thoracic artery were measured using intercostal duplex scanning in 100 patients during April 1995. The ultrasonographic device (sonos 2000, Hewlett Packard) used had a linear probe delivering a frequency of 7.5 MHz. Bilateral internal thoracic arteries and their blood flow were imaged clearly in all subjects. Diameter was compared by angiography and duplex scanning ultrasonography in 20 patients. RESULTS: The average internal diameter of internal thoracic artery was 2.19 +/- 0.46 mm (right) or 2.13 +/- 0.32 mm (left) in men and 2.05 +/- 0.44 mm (right) or 2.09 +/- 0.42 mm (left) in women. The gender difference was statistically significant (p = 0.05). The maximum systolic blood flow velocity through the internal thoracic artery was 0.85 +/- 0.34 m/s (right) or 0.84 +/- 0.36 m/s (left) in men and 0.87 +/- 0.28 m/s (right) or 0.82 +/- 0.28 m/s (left) in women. The average internal thoracic arterial blood flow (F) was 54.6 +/- 29.0 ml/min (right) or 50.9 +/- 28.8 ml/min (left) in men and 56.8 +/- 38.2 ml/min (right) or 58.2 +/- 33.4 ml/min (left) in women. Duplex scanning ultrasonography using an intercostal approach enables easy imaging of bilateral internal thoracic arteries and visualizes entire internal thoracic artery structure by simply changing the probe position. CONCLUSION: Intercostal duplex scanning ultrasonography is thus recommended for reliable evaluation of the internal diameter and blood flow of the internal thoracic artery.

Aged↗
PubMed2001

Chronic extrinsic denervation after small bowel transplantation in rat jejunum: Effects and adaptation in nitrergic and non-nitrergic neuromuscular inhibitory mechanisms.

BACKGROUND: Extrinsic denervation of the transplanted small bowel could play a substantial role in motor dysfunction of the transplanted gut. We attempted to determine the effect of chronic extrinsic denervation on intestinal contractility. METHODS: Jejunal longitudinal muscle strips were obtained from rats 1 week and 8 weeks after (1) syngeneic small bowel transplantation, (2) ischemia/reperfusion, or (3) gut transection/reanastomosis. Nonoperated rats (naive controls) and sham-operated rats (sham controls), 1 week after celiotomy/gut manipulation, served as controls. We evaluated the effects of exogenous nitric oxide, increasing doses of cholinergic and adrenergic agonists, and electrical field stimulation (EFS) in the presence or absence of N(G)-monomethyl-l-arginine, methylene blue, tetraethylammonium, or tetrodotoxin. RESULTS: Spontaneous contractile activity (_chi +/- SEM), when compared with the naive controls (11.3 +/- 2.0 g.5 min/mg), was increased in all 4 groups at 1 week (15.9 +/- 10 to 19.4 +/- 2 g.5 min/mg; P < or =.03 each) but not at 8 weeks postoperatively. The inhibition of contractile activity by nitric oxide was increased in small bowel transplantation in naive controls at 8 weeks to 80% +/- 10% versus 50% +/- 7% (P <.02). EFS induced an inhibition of contractile activity that was tetraethylammonium- and tetrodotoxin-sensitive but N(G)-monomethyl-l-arginine- and methylene blue-insensitive; the maximal EFS-induced inhibition was increased at 1 week and 8 weeks but only in the small bowel transplantation groups to 103% +/- 5% and 95% +/- 7%, respectively, versus 72% +/- 8% in naive controls (P </=.05). CONCLUSIONS: [corrected] Increased inhibition of contractile function after small bowel transplantation lasts at least 8 weeks and is mediated by changes in the enteric neuromuscular unit caused by extrinsic denervation.

Adaptation, Physiological↗
PubMed2001

Heat labile ribonuclease HI from a psychrotrophic bacterium: gene cloning, characterization and site-directed mutagenesis.

The rnhA gene encoding RNase HI from a psychrotrophic bacterium, Shewanella sp. SIB1, was cloned, sequenced and overexpressed in an rnh mutant strain of Escherichia coli. SIB1 RNase HI is composed of 157 amino acid residues and shows 63% amino acid sequence identity to E.coli RNase HI. Upon induction, the recombinant protein accumulated in the cells in an insoluble form. This protein was solubilized and purified in the presence of 7 M urea and refolded by removing urea. Determination of the enzymatic activity using M13 DNA-RNA hybrid as a substrate revealed that the enzymatic properties of SIB1 RNase HI, such as divalent cation requirement, pH optimum and cleavage mode of a substrate, are similar to those of E.coli RNase HI. However, SIB1 RNase HI was much less stable than E.coli RNase HI and the temperature (T(1/2)) at which the enzyme loses half of its activity upon incubation for 10 min was approximately 25 degrees C for SIB1 RNase HI and approximately 60 degrees C for E.coli RNase HI. The optimum temperature for the SIB1 RNase HI activity was also shifted downward by 20 degrees C compared with that of E.coli RNase HI. Nevertheless, SIB1 RNase HI was less active than E.coli RNase HI even at low temperatures. The specific activity determined at 10 degrees C was 0.29 units/mg for SIB1 RNase HI and 1.3 units/mg for E.coli RNase HI. Site-directed mutagenesis studies suggest that the amino acid substitution in the middle of the alphaI-helix (Pro52 for SIB1 RNase HI and Ala52 for E.coli RNase HI) partly accounts for the difference in the stability and activity between SIB1 and E.coli RNases HI.

Alanine↗
PubMed2000

Stanford type A acute dissection developing acute myocardial infarction.

A 75-year-old female, exhibiting epigastric pain and vomiting, underwent treatment for acute gastritis. She also experienced incontinence of urine and chest pain. A diagnosis of acute myocardial infarction was made upon examination of electrocardiographic findings and the patient was transferred to our hospital. Diffuse infarction of the left ventricle and acute aortic dissection (Stanford type A) were diagnosed by electrocardiographic and echo-cardiography. An emergency operation was performed. After induction of anesthesia, elevation of pulmonary artery pressure and fall of pulse pressure were observed, indicating acute cardiac tamponade. Transesophageal ultrasonography disclosed the entry of dissection in the descending aorta. Dissection of the aorta extended proximally up to the annulus of the aortic valve and the right and left coronary arteries were compressed by its aneurysm. As aortic insufficiency was mild, only reconstruction of the ascending aorta was carried out. The patient was discharged in fair condition one month after operation under use of postoperative long-term administration of catecholamines.

Aged↗
PubMed2000

Thoracic aortic aneurysm complicated with severe coronary arterial occlusive disease.

The patient was a 77-year-old female who had been treated medically for angina pectoris since 5 years ago. Expanded aneurysms in the distal aortic arch and in the descending thoracic aorta were seen during follow-up. She presented continuous back-pain at rest along with increasing size of the aneurysms despite antihypertensive therapies after admission. First, two saphenous vein grafts were anastomosed to the left anterior descending artery and obtuse marginal artery under beating heart. Next, the proximal portion of the left subclavian artery was clamped and divided. To this graft, the proximal ends of the coronary bypassed vein grafts were anastomosed and coronary perfusion was established and maintained until this artery was anastomosed to the aortic graft. Then, the aneurysms in the distal arch and descending thoracic aorta were excised and the aorta and its two pairs of intercostal arteries were reconstructed. The Postoperative course was uneventful with favorable cardiac function.

Aged↗
PubMed2000

Optically clear nuclei in papillary carcinoma of the thyroid: demonstration of one of the fixation artifacts and its practical usefulness.

To examine whether or not optically clear nuclei are one of the fixation artifacts in papillary carcinoma of the thyroid. Experiments using an optimal immersion fixation method by making thin-sliced specimens, 5 x 2 x 2 mm in size were adopted. Fixatives tested were 10% formalin, 10% buffered formalin, mixture of alcohol and formalin (4: 1), 95% alcohol, 4% phosphate-buffered paraformaldehyde, Carnoy's fixative, Bouin's fixative and various concentrations of formalin. Tested thyroid lesions in total were: cases with papillary carcinoma (38); follicular carcinoma (one); follicular adenoma (15); adenomatous goiter (11); Hashimoto's thyroiditis (two); Grave's disease (five); and normal thyroid tissue around tumor (five). Routinely processed papillary carcinoma showed a high occurrence (64.6%) of the optically clear nuclei contrasted by a low occurrence (almost 0%) in other lesions. However, this rate in papillary carcinoma decreased (< 35.3%) in all experimental groups irrespective of the choice of fixatives. Frequent occurrence (61.9-66.6%) of the optically clear nuclei was reproduced in papillary carcinoma fixed in a higher concentration of formalin (40-60%) in the experimental groups. These results demonstrated that the optically clear nuclei are one of the fixation artifacts, although still useful as a diagnostic criterion.

Adenocarcinoma, Follicular↗
PubMed2000

Characterization of ribonuclease HII from Escherichia coli overproduced in a soluble form.

Escherichia coli RNase HII is composed of 198 amino acid residues. The enzyme has been overproduced in an insoluble form, purified in a urea-denatured form, and refolded with poor yield [M. Itaya (1990) Proc. Natl. Acad. Sci. USA 87, 8587-8591]. To facilitate the preparation of the enzyme in an amount sufficient for physicochemical studies, we constructed an overproducing strain in which E. coli RNase HII is produced in a soluble form. The enzyme was purified from this strain and its biochemical and physicochemical properties were characterized. The good agreement in the molecular weights estimated from SDS-PAGE (23,000) and gel filtration (22,000) suggests that the enzyme acts as a monomer. From the far-UV circular dichroism spectrum, its helical content was calculated to be 23%. The enzyme showed Mn(2+)-dependent RNase H activity. Its specific activity determined using (3)H-labeled M13 RNA/DNA hybrid as a substrate was comparable to but slightly higher than that of the refolded enzyme, indicating that the enzyme overproduced and purified in a soluble form is more suitable for structural and functional analyses than the refolded enzyme.

Bacterial Proteins↗
PubMed2000

An experience of a case with perforation of an aneurysm in the anterior mitral cusp developing after aortic valve replacement.

Mitral valve aneurysm is a rare disease and in Japan, cases of perforation which is considered to be mainly caused by infectious endocarditis is usually only encountered through case reports. We experienced a case who received aortic valve replacement and mitral valve annuloplasty for combined valvular heart disease of aortic insufficiency and mitral insufficiency followed by mitral valve replacement for severe mitral valve regurgitation subsequent to perforation of the anterior mitral cusp, leading to recovery.

Aneurysm, Ruptured↗
PubMed1999

Regulation of CDK4 activity by a novel CDK4-binding protein, p34(SEI-1).

The p16(INK4a) tumor suppressor inhibits cyclin-dependent kinases (CDK4 and CDK6). Here we report the isolation of a novel gene, SEI-1, whose product (p34(SEI-1)) appears to antagonize the function of p16(INK4a). Addition of p34(SEI-1) to cyclin D1-CDK4 renders the complex resistant to inhibition by p16(INK4a). Expression of SEI-1 is rapidly induced on addition of serum to quiescent fibroblasts, and ectopic expression of p34(SEI-1) enables fibroblasts to proliferate even in low serum concentrations. p34(SEI-1) seems to act as a growth factor sensor and may facilitate the formation and activation of cyclin D-CDK complexes in the face of inhibitory levels of INK4 proteins.

Animals↗
PubMed1999

Alterations in monoamines and GABA in the ventromedial and paraventricular nuclei of the hypothalamus following cold exposure: a reduction in noradrenaline induces hyperphagia.

A microdialysis technique for the in vivo assessment of the monoaminergic and GABAergic levels in the ventromedial (VMN) and paraventricular nuclei (PVN) of the hypothalamus was used in order to examine the activities of neurons that project to the hypothalamic regions and are implicated in the regulation of ingestive behavior and energy balance. Cold exposure increased food intake, as well as the circulating levels of glucose, noradrenaline (NA), 3,5,3'-triiodothyronine, and corticosterone. The dialysate concentrations of NA, dopamine (DA), serotonin (5-HT), and gamma-aminobutyric acid (GABA) in the VMN all decreased after exposure to cold. The changes in extracellular NA, DA, and GABA in the PVN under cold conditions were similar to those in the VMN. NA release in the VMN or PVN was decreased after local electrolytic lesions, which significantly increased food intake. Thus, low activities of noradrenergic axons of neurons terminating in the VMN and PVN may be a good mechanism to induce feeding behavior. Extracellular 5-HT in the PVN was significantly increased, along with a significant decrease in 5-hydroxyindoleacetic acid, in cold-exposed rats, suggesting that serotonergic fibers terminating in the PVM are more closely related to the increases in adrenocortical and thyroid hormone secretion than to food intake. The neuronal activities, indicating that a sympathetic tone is activated on stimulation of the VMN and/or PVN, may be changes in GABAergic and/or serotonergic neurons.

Animals↗
PubMed1999

Identification of the genes encoding Mn2+-dependent RNase HII and Mg2+-dependent RNase HIII from Bacillus subtilis: classification of RNases H into three families.

Database searches indicated that the genome of Bacillus subtilis contains three different genes encoding RNase H homologues. The ypdQ gene encodes an RNase HI homologue with 132 amino acid residues, whereas the rnh and ysgB genes encode RNase HII homologues with 255 and 313 amino acid residues, respectively. RNases HI and HII show no significant sequence similarity. These genes were individually expressed in Escherichia coli; the recombinant proteins were purified, and their enzymatic properties were compared with those of E. coli RNases HI and HII. We found that the ypdQ gene product showed no RNase H activity. The 2.2 kb pair genomic DNA containing this gene did not suppress the RNase H deficiency of an E. coli rnhA mutant, indicating that this gene product shows no RNase H activity in vivo as well. In contrast, the rnh (rnhB) gene product (RNase HII) showed a preference for Mn2+, as did E. coli RNase HII, whereas the ysgB (rnhC) gene product (RNase HIII) exhibited a Mg2+-dependent RNase H activity. Oligomeric substrates digested with these enzymes indicate similar recognition of these substrates by B. subtilis and E. coli RNases HII. Likewise, B. subtilis RNase HIII and E. coli RNase HI have generated similar products. These results suggest that B. subtilis RNases HII and HIII may be functionally similar to E. coli RNases HII and HI, respectively. We propose that Mn2+-dependent RNase HII is universally present in various organisms and Mg2+-dependent RNase HIII, which may have evolved from RNase HII, functions as a substitute for RNase HI.

Amino Acid Sequence↗
PubMed1999

Poststernotomy mediastinitis treated by rectus muscle flap plugging.

The current standard treatment of mediastinitis following median sternotomy is radical sternal curettage and plugging of the anterior mediastinal dead space with muscle flap or omentum. This paper will report our experience with a pediculated flap of the rectus muscle after mediastinal irrigation and drainage. The patient was a 75-year-old man diagnosed as having aortic arch aneurysm. The patient underwent a total aortic arch replacement with the bovine-collagen sealed vascular prosthesis (Hemashield). As an early postoperative complication, he was diagnosed with mediastinitis which was the result of infection of the drainage fluid. Mediastinal curettage and plugging of the rectus muscle flap was successfully performed. Without recurrence of infection, the wound healed completely. We conclude that early curettage and rectus muscle flap plugging are the most effective treatment of the poststernotomy mediastinitis.

Aged↗
PubMed1999

Molecular diversities of RNases H.

RNase H is an enzyme that specifically cleaves RNA hybridized to DNA. The enzyme is ubiquitously present in various organisms. Single bacterial and eucaryotic cells often contain two RNases H, whereas single archaeal cells contain only one. To determine whether there is a physiological significance in the ubiquity and multiplicity of the enzyme, and whether all enzymes are evolutionarily diverged from a common ancestor, we carried out phylogenetic analyses of the RNase H sequences. In this report, we demonstrated that RNases H are classified into two major families, Type 1 and Type 2 RNases H, of which only the Type 2 enzymes are present in all living organisms, including bacteria, archaea, and eucaryotes, suggesting that they represent an ancestral form of RNases H. Based on this information, we discuss the evolutionary relationships and possible cellular functions of RNases H.

Journal Article↗