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Biomedical subjects

K Ishihara

Publications and source records attributed to K Ishihara.

At least 37 records · Page 2Linked to original sources
PubMed2004

Limits on the neutrino magnetic moment using 1496 days of Super-Kamiokande-I solar neutrino data.

A search for a nonzero neutrino magnetic moment has been conducted using 1496 live days of solar neutrino data from Super-Kamiokande-I. Specifically, we searched for distortions to the energy spectrum of recoil electrons arising from magnetic scattering due to a nonzero neutrino magnetic moment. In the absence of a clear signal, we found micro(nu)</=(3.6x10(-10))micro(B) at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The fitting took into account the effect of neutrino oscillation on the shapes of energy spectra. With additional information from other solar neutrino and KamLAND experiments constraining the oscillation region, a limit of micro(nu)</=(1.1x10(-10))micro(B) at 90% C.L. was obtained.

Journal Article↗
PubMed2004

High sensitivity search for nu;e's from the sun and other sources at KamLAND.

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for nu;(e)'s in the energy range 8.3<E(nu;(e))<14.8 MeV. No candidates were found for an expected background of 1.1+/-0.4 events. This result can be used to obtain a limit on nu;(e) fluxes of any origin. Assuming that all nu;(e) flux has its origin in the Sun and has the characteristic 8B solar nu(e) energy spectrum, we obtain an upper limit of 3.7 x 10(2) cm(-2) s(-1) (90% C.L.) on the nu;(e) flux. We interpret this limit, corresponding to 2.8 x 10(-4) of the standard solar model 8B nu(e) flux, in the framework of spin-flavor precession and neutrino decay models.

Journal Article↗
PubMed2004

Involvement of periodontopathic biofilm in vascular diseases.

Oral bacteria inhabit biofilms, which are firm clusters adhering in layers to surfaces and are not easily eliminated by immune responses and are resistant to antimicrobial agents. Dental plaque is one such biofilm. In the past 10 years, subgingival plaque bacteria forming biofilms have been increasingly reported to be involved in systemic diseases. A close relationship between microbial infections and vascular disease has also been reported in the past two decades. The present review discusses the significance of the ecologic characteristics of biofilms formed by periodontopathic bacteria in order to further clarify the associations between periodontal disease and systemic disease. We focus on the relationships between periodontal disease-associated bacteria forming biofilms and vascular diseases including atherosclerosis and carotid coronary stenotic artery disease, and we discuss the direct and indirect effects on vascular diseases of lipopolysaccharides as well as heat shock proteins produced by periodontopathic bacteria.

Arteriosclerosis↗
PubMed2003

Reduction of diet-induced obesity in transgenic mice overexpressing uncoupling protein 3 in skeletal muscle.

AIMS/HYPOTHESIS: It has been suggested that uncoupling protein 3 (UCP3) can increase energy expenditure, thereby regulating body weight. Although studies on UCP3 knock-out mice suggest that lack of UCP3 function does not cause obesity or Type 2 diabetes, it is possible that up-regulation of UCP3 function improves these disorders or their clinical sequelae. A 10- to 20-fold increase of UCP3 gene expression is achievable through physiological or pharmacological stimuli. We examined the phenotype of transgenic mice with approximately 18-fold overexpression of mouse UCP3 mRNA in skeletal muscle. METHODS: We generated transgenic mice with approximately 18-fold overexpression of mouse UCP3 mRNA in skeletal muscle under control of the skeletal muscle-specific muscle creatine kinase gene promoter. The phenotype of these mice was analysed either on a standard diet or on a 4-week high-fat diet. RESULTS: In mice on standard chow, there was no difference in body weight, oxygen consumption and mitochondrial protonmotive force between transgenic mice and non-transgenic littermates. However, transgenic mice tended to have lower body weight, increased oxygen consumption and decreased mitochondrial protonmotive force than the control mice. Transgenic mice on a 4-week high-fat diet consumed much more oxygen and had noticeably less weight gain and less epididymal fat, as well as better glucose tolerance than non-transgenic littermates. CONCLUSIONS/INTERPRETATION: Our study shows that 18-fold overexpression of UCP3 mRNA in the skeletal muscle reduced diet-induced obesity. An 18-fold increase of UCP3 mRNA can be attained by physiological or pharmacological stimuli, suggesting that UCP3 has therapeutic potential in the treatment of obesity.

Aging↗
PubMed2003

IL-6 signal transduction and its physiological roles: the signal orchestration model.

Interleukin (IL)-6 is a pleiotropic cytokine that not only affects the immune system, but also acts in other biological systems and many physiological events in various organs. In a target cell, IL-6 can simultaneously generate functionally distinct or sometimes contradictory signals through its receptor complex, IL-6Ralpha and gp130. One good illustration is derived from the in vitro observations that IL-6 promotes the growth arrest and differentiation of M1 cells through gp130-mediated STAT3 activation, whereas the Y759/SHP-2-mediated cascade by gp130 stimulation has growth-enhancing effects. The final physiological output can be thought of as a consequence of the orchestration of the diverse signaling pathways generated by a given ligand. This concept, the signal orchestration model, may explain how IL-6 can elicit proinflammatory or anti-inflammatory effects, depending on the in vivo environmental circumstances. Elucidation of the molecular mechanisms underlying this issue is a challenging subject for future research. Intriguingly, recent in vivo studies indicated that the SHP-2-binding site- and YXXQ-mediated pathways through gp130 are not mutually exclusive but affect each other: a mutation at the SHP-2-binding site prolongs STAT3 activation, and a loss of STAT activation by gp130 truncation leads to sustained SHP-2/ERK MAPK phosphorylation. Although IL-6/gp130 signaling is a promising target for drug discovery for many human diseases, the interdependence of each signaling pathway may be an obstacle to the development of a nonpeptide orally active small molecule to inhibit one of these IL-6 signaling cascades, because it would disturb the signal orchestration. In mice, a consequence of the imbalanced signals causes unexpected results such as gastrointestinal disorders, autoimmune diseases, and/or chronic inflammatory proliferative diseases. However, lessons learned from IL-6 KO mice indicate that IL-6 is not essential for vital biological processes, but a significant impact on disease progression in many experimental models for human disorders. Thus, IL-6/gp130 signaling will become a more attractive therapeutic target for human inflammatory diseases when a better understanding of IL-6 signaling, including the identification of the conductor for gp130 signal transduction, is achieved.

Acute-Phase Reaction↗
PubMed2003

cDNA cloning and functional expression of alpha-glucosidase from Mortierella alliacea.

We recently purified an alpha-glucosidase comprising 61-kDa and 31-kDa subunits from the fungus Mortierella alliacea and characterized its soluble starch-hydrolyzing activity. Here, the cDNA coding for this enzyme was cloned, revealing that it encodes a single polypeptide of 1,053 amino acids, with a calculated molecular mass of 117 kDa. Comparison between the deduced amino acid sequence and the partial sequences of the purified enzyme suggested that an immature protein can be converted into the two subunits of mature enzyme by post-translational processing at least three cleavage sites. Heterologous expression of recombinant alpha-glucosidase in yeast gave rise to a significant increase in hydrolytic activity toward maltose and soluble starch, in both intracellular and extracellular fractions. Immunoblot analysis using antiserum against the alpha-glucosidase revealed that the active enzyme expressed in yeast is also composed of two subunits. The yeast expression system provides a model suitable for investigating the polypeptide-processing event and structure-function relationship of the alpha-glucosidase with unique substrate specificity.

Amino Acid Sequence↗
PubMed2003

First results from KamLAND: evidence for reactor antineutrino disappearance.

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.

Journal Article↗
PubMed2003

PCR method is essential for detecting Mycobacterium tuberculosis in oral cavity samples.

Tuberculosis is a re-emerging infectious disease, and infection by Mycobacterium tuberculosis has been increasing in immunocompromised hosts, including elderly persons. M. tuberculosis-infected persons may receive dental treatment. To evaluate the risk of M. tuberculosis infection in dental clinics, we examined the detection rates of M. tuberculosis in sample of mixed saliva, dental plaque, extracted teeth, caries lesions, and denture plaque by nested polymerase chain reaction (PCR). The detection rates by PCR in samples from mixed saliva, dental plaque, caries lesions and denture plaque obtained from tuberculosis patients were 98.0%, 92.0%, 89.0%, and 100%, respectively. The detection rates by the culture method were 17.3%, 2.0%, 0%, and 0%, respectively. M. tuberculosis also was detected from the nontuberculous mycobacteria-infected group. Strains of Actinomyces naeslundii, Porphyromonas gingivalis, and Fusobacterium nucleatum inhibited the growth of clinical strains of M. tuberculosis, but strains of Streptococcus mutans, Streptococcus sanguinis, and Actinobacillus actinomycetemcomitans did not. The present study concludes that the PCR method is essential for detecting M. tuberculosis in oral samples.

Aerosols↗
PubMed2003

Midterm results of conservative repair of the incompetent bicuspid aortic valve.

AIM: Repair of the bicuspid aortic valve is not generally considered the treatment of choice. Our success with this procedure leads us to report our immediate and mid-term RESULTS METHODS: From August 1993 to December 2000, 19 patients with aortic regurgitation due to congenital aortic valve underwent aortic valve repair (17 men and 2 women with a mean age of 42+/-17 years; range, 16 to 70 years). The mean preoperative aortic regurgitation grade was 3.1+/-0.8 on a scale of 1 to 4. Mean preoperative New York Heart Association functional class was 1.9+/-0.8. Fourteen patients had pure aortic regurgitation, 2 also had infectious endocarditis, 1 had angina pectoris, and 2 had an ascending aortic aneurysm. RESULTS: There was 1 hospital death (5.2%), and 1 patient required re-operation due to recurrent infectious endocarditis. Mean aortic regurgitation grade at discharge was 1.1+/-0.9, and functional class was 1.1+/-0.2. All patients were followed for a mean duration of 40+/-23 months (range, 0.5 to 84 months). There was 1 late death, and two patients required aortic valve replacement. The 5-year survival rate was 90+/-7%. The 1- and 5-year re-operation-free rates were 87+/-12% and 76+/-23%. CONCLUSIONS: Bicuspid aortic valve repair is a safe procedure with good early postoperative RESULTS: However midterm results are not satisfactory. Re-operation is a promising alternative and progress aortic regurgitation were complications. Bicuspid aortic valve repair to valve replacement that requires additional study to individualize treatment.

Adolescent↗
PubMed2003

[Aortic valve repair with minimal access "J" sternotomy].

Recently many cardiovascular operations have been performed with minimally invasive cardiac surgery (MICS). It is reported that MICS is superior to standard full sternotomy in regard to cosmetic and post-operative recovery. In our institution, aortic valve repair operations have been performed to aortic valve insufficiency. This time, we performed aortic valve repair by minimal access "J" sternotomy. A 63-year-old male with degenerative aortic regurgitation underwent aortic valve repair by MICS. He had experienced dyspnea on exertion 7 days before admission. Preoperative transthoracic echocardiogram showed the grade of aortic regurgitation (AR) was severe. Surgery was successful and the grade of AR became trivial. This combined procedure have merits for patients because of freedom from anticoagulation and small incision. Such combined surgery may be indicated in the treatment in a subset of patients with degenerative AR.

Aortic Valve↗
PubMed2002

Dietary-fiber-degrading enzymes from a human intestinal Clostridium and their application to oligosaccharide production from nonstarchy polysaccharides using immobilized cells.

The secretion of nonstarchy polysaccharide-degrading enzymes from an anaerobic human intestinal bacterium, Clostridium butyricum- beijerinckii (isolated from human feces), was investigated. Growth of the bacterium was found when laminarin, konjac glucomannan, and pectic acid were added separately to the culture media as sole carbon source. The corresponding degrading enzymes for these dietary fibers, laminarinase (endo-1,3- beta-glucanase), endo-1,4-beta-mannanase, endo- and exo-pectate lyases, and pectin methylesterase, were then purified and characterized. These extracelluar enzymes, which were secreted by the bacterium in the human large intestine, were considered to contribute to digestion of the ingested dietary fibers to their oligosaccharides, following by short-chain fatty acid fermentation by the bacterium. We have developed cell immobilization techniques of the bacterium on cellulose-foam carriers that are effective for continuous production of the oligosaccharides from the dietary fibers in a fed-batch reactor system. From 9 g of pectic acid, a total of 3.96 g of 4,5-unsaturated digalacturonic acid was produced over 40 h in four 500-ml batchcultures. In the same manner, the corresponding oligosaccharides were obtained from konjac glucomannan and laminarin with average conversion rates of around 30-40%.

Adsorption↗
PubMed2002

Tyrosine 759 of the cytokine receptor gp130 is involved in Listeria monocytogenes susceptibility.

Interleukin-6 family cytokines have been implicated in adaptive and innate immunity, hematopoiesis, and inflammation. This cytokine family shares a signal-transducing receptor subunit called gp130. gp130(F759/F759) knockin mice carry a point mutation at the SHP2-binding site of gp130 due to the replacement of tyrosine-759 (Y759 for human gp130) with phenylalanine (F). To explore the effect of this point mutation on the host response to bacterial infection, gp130(F759/F759) knockin mice were infected with Listeria monocytogenes. gp130(F759/F759) knockin mice began to die at 3 to 4 days post infection (p.i.) and showed higher mortality than did controls. Listeria titers at 3 days p.i. in the peritoneal cavity, spleen, and liver were significantly higher in gp130(F759/F759)knockin mice than in controls. Nitric oxide production, upregulation of the mRNA levels of a variety of cytokines, and listericidal activity in gp130(F759/F759) macrophages were unchanged. However, gp130(F759/F759) knockin mice displayed significantly lower levels of interferon (IFN)gamma in serum and in the culture supernatant from peritoneal exudate cells and splenocytes, in response to Listeria infection. These results suggest that the Y759 point mutation in gp130 attenuates the early phase of defense against Listeria infection, possibly owing to insufficient elevation of IFNgamma levels, and thus gp130 is a possible candidate gene for Listeria susceptibility.

Animals↗
PubMed2002

Beneficial effects of synthetic phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate), on stratum corneum function.

The effects of a newly synthesized phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) [poly(MPC-co-BMA)], on the water barrier function and water-holding capacity of the stratum corneum were examined by measuring transepidermal water loss (TEWL) and electrical conductance of the skin surface. On the backs of four NC mice, the epidermal permeability barrier was abrogated by cellophane tape stripping 30 times. The skin was then treated with 0.1% poly(MPC-co-BMA) or distilled water twice daily for the following 3 days. Poly(MPC-co-BMA) reduced TEWL significantly compared with the control after the first treatment (P = 0.044) and this effect was observed for 3 days. In human skin, water-holding capacity was measured at 5, 10, 15, 30 min and 1, 2, and 4 h after the application of poly(MPC-co-BMA) or distilled water to both volar forearms of 21 healthy volunteers. Skin treated with poly(MPC-co-BMA) showed significantly greater ability to retain water at all time points. Poly(MPC-co-BMA) is the first synthetic material that can enhance both the water barrier function and water-holding capacity of the stratum corneum. Our results indicate that this substance may be useful clinically in the treatment of dry skin.

Adult↗
PubMed2002

Brain infarction after percutaneous implantation of port-catheter system via the left subclavian artery.

The aim of this study was to evaluate the incidence of brain infarction after percutaneous implantation of a port-catheter system via the left subclavian artery for hepatic arterial infusion chemotherapy. In 90 patients with inoperable liver cancer, a port-catheter system was implanted via the left subclavian artery. In 5 patients (5.6%) brain infarction occurred after port-catheter implantation. In one patient (1.1%) thrombi formed around the catheter, as confirmed by autopsy. The risk of brain infarction should be taken into consideration when a trans-left subclavian arterial access route is used for the percutaneous implantation of a port-catheter system for hepatic arterial infusion chemotherapy.

Adult↗
PubMed2002

[Giant coronary artery aneurysm in diagonal artery; report of a case].

We report a giant coronary artery aneurysm occurred in the diagonal artery. A 44-year-old woman was referred to our institution for further examination of chest X-ray abnormality. Computed tomography revealed a 6 cm intracardiac mass adjacent to pulmonary artery. Cardiac catheterization revealed a giant coronary artery aneurysm with the large thrombus in the diagonal artery. A giant aneurysm 6 cm in diameter was exposed through a median sternotomy. Under beating heart with cardiopulmonary bypass, the aneurysm was opened and organized thrombus was removed. The influx and efflux of the aneurysm were identified and ligated. Under arrested heart with cardioplegia, the diagonal artery was bypassed with the left internal thoracic artery. Finally the aneurysm was obliterated with the running suture. The patient discharged at the 17th postoperative day without any complications. Histologic evaluation of the resected aneurysm revealed atherosclerotic change, destruction of vascular layers and infiltration of inflammatory cells. These findings suggested previous history of coronary arteritis. The coronary aneurysm in this case might be resulted from Kawasaki disease.

Adult↗
PubMed2002

[Redo coronary artery bypass grafting using the patent left internal thoracic artery graft as an in flow with composite internal thoracic artery Y grafting; report of a case].

In redo coronary artery bypass grafting (CABG), graft selection and revascularization methods are major problems. We experienced a redo-CABG with occluded previous vein grafts. These grafts were to the circumflex artery and right coronary artery. We conducted operation using cardiopulmonary bypass. We at this operation, chose right internal thoracic artery (RITA) as a conduit and anastomosed it to the side of functioning left internal thoracic artery (LITA) graft, and then diogonal branch, posterolateral branch, and atrioventricular branch were revascularized with the RITA. Post operative course was uneventful. Internal thoracic artery (ITA) is superior to vein graft and other arterial graft as to long term patency. We believe composite Y graft with the use of bilateral ITA can be one of the revascularization strategy in redo CABG.

Coronary Artery Bypass↗