PubMed Health⌕ Search

Biomedical subjects

Y Tsuda

Publications and source records attributed to Y Tsuda.

At least 19 recordsLinked to original sources
PubMed2006

Search for the invisible decay of neutrons with KamLAND.

The Kamioka Liquid scintillator Anti-Neutrino Detector is used in a search for single neutron or two-neutron intranuclear disappearance that would produce holes in the -shell energy level of (12)C nuclei. Such holes could be created as a result of nucleon decay into invisible modes (inv), e.g., n--> 3v or nn--> 2v. The deexcitation of the corresponding daughter nucleus results in a sequence of space and time-correlated events observable in the liquid scintillator detector. We report on new limits for one- and two-neutron disappearance: tau(n--> inv) > 5.8 x 10(29) years and tau (nn--> inv) > 1.4 x 10(30) years at 90% C.L. These results represent an improvement of factors of approximately 3 and >10(4) and over previous experiments.

Journal Article↗
PubMed2006

[Apicoaortic conduit insertion for elderly patients with acquired aortic stenosis and small aortic annulus].

BACKGROUND: Patients with critical aortic stenosis, a heavily calcified aorta, and a small aortic annulus are at an increasing risk of complications during a conventional aortic valve replacement (AVR) procedure. Insertion of an apicoaortic conduit (AAC) can be an alternative to AVR in such situations. This study is a review of our experiences with AAC in elderly patients with acquired aortic stenosis. METHOD: From 2001 to 2005, 7 elderly patients (mean age of 81 : range 74 to 87) underwent an AAC insertion for severe symptomatic aortic stenosis with a small aortic annulus (mean annulus size 17.9 mm). Preoperatively, all were symptomatic, with 4 rated as New York Heart Association (NYHA) functional class IV, 2 as class III, and 1 as class II. In addition, 3 patients had severe congestive heart failure with mechanical ventilation and received a high dose administration of catecholamine, and 1 had undergone coronary artery bypass grafting (CABG) previously. RESULT: The AAC insertions were performed under a cardiopulmonary bypass through a left thoracotomy in 6 patients, while 1 patient underwent the procedure without a cardiopulmonary bypass. Distal anastomoses were performed in the descending thoracic aorta with a partial occluding clamp. A composite woven Dacron conduit with a stented biological valve was used in 2 cases, and a woven Dacron conduit with a stentless bioprosthesis was used in 5. Two patients underwent a concomitant CABG. There was 1 hospital death due to obstructive ileus 4 months after the operation. One patient who had been in a shock state preoperatively had hypoxic encephalopathy due to inoperative severe hypotension. Postoperative echocardiography showed relief of the left ventricle-aortic gradient in all patients. After a mean follow-up period of 22 months, there was no late death, while 3 patients were readmitted due to congestive heart failure. Further, 1 of the patients was rated as NYHA class I, 1 as class II, and 2 as class III. CONCLUSION: An AAC procedure was found to be an acceptable alternative for elderly patients who had a high-risk of complications with the standard procedure.

Aged↗
PubMed2005

Experimental investigation of geologically produced antineutrinos with KamLAND.

The detection of electron antineutrinos produced by natural radioactivity in the Earth could yield important geophysical information. The Kamioka liquid scintillator antineutrino detector (KamLAND) has the sensitivity to detect electron antineutrinos produced by the decay of 238U and 232Th within the Earth. Earth composition models suggest that the radiogenic power from these isotope decays is 16 TW, approximately half of the total measured heat dissipation rate from the Earth. Here we present results from a search for geoneutrinos with KamLAND. Assuming a Th/U mass concentration ratio of 3.9, the 90 per cent confidence interval for the total number of geoneutrinos detected is 4.5 to 54.2. This result is consistent with the central value of 19 predicted by geophysical models. Although our present data have limited statistical power, they nevertheless provide by direct means an upper limit (60 TW) for the radiogenic power of U and Th in the Earth, a quantity that is currently poorly constrained.

Journal Article↗
PubMed2005

Measurement of neutrino oscillation with KamLAND: evidence of spectral distortion.

We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.

Journal Article↗
PubMed2005

Population pharmacokinetics of epinastine, a histamine H1 receptor antagonist, in adults and children.

AIMS: Our objective was to develop a population pharmacokinetic (PPK) model for epinastine, a histamine H(1) receptor antagonist, in adults and children and to obtain pharmacokinetic information to support dosing recommendations in children. METHODS: A total of 1510 plasma samples were collected from 62 healthy adult volunteers and 62 paediatric atopic dermatitis patients. The data were analysed using the NONMEM program according to a two-compartment model with first-order absorption. In addition, the final PPK model was evaluated by means of bootstrapping resampling. RESULTS: The oral clearance (CL/F) was found to be associated with body weight, formulation and food status. The volume of distribution of the central compartment (V(1)/F) was related to body weight and food status. An absorption lag time was apparent in fed subjects. On the other hand, other covariates (formulation on V(1)/F, volume of distribution of the peripheral compartment (V(2)/F), first-order absorption rate constant (Ka) and absorption lag time (ALAG); food status on V(2)/F and Ka; body weight on V(2)/F) were not statistically significant. No effect of age on CL/F, V(1)/F or V(2)/F was found. The mean parameter estimates obtained with an additional 200 bootstrap replicates of data were within 90-117% of those obtained with the original data set. These results suggest that the pharmacokinetics of epinastine are similar in adults and in children, except for the effect of the difference of body weight. The result of the application of the PPK model to the clinical trial in paediatric patients, in which dosage was determined based on the body weight (from 14 kg to less than 24 kg; 10 mg dose, 24 kg or more; 20 mg dose), showed that the C(max) and AUC (25.6 +/- 6.9 ng ml(-1) and 246.8 +/- 68.2 ng h ml(-1)) were almost same levels with those of adults after administration of 20 mg (26.9 +/- 9.1 ng ml(-1) and 281.6 +/- 90.5 ng h ml(-1)). CONCLUSIONS: A PPK model for epinastine was established and further evaluation by bootstrapping indicated that this model is stable. The model shows that, if dosage is adjusted based on the body weight, the epinastine exposure in paediatric patients is similar to that in adults.

Adult↗
PubMed2005

Wide-range analysis of genetic structure of Betula maximowicziana, a long-lived pioneer tree species and noble hardwood in the cool temperate zone of Japan.

Betula maximowicziana is a long-lived pioneer tree species in Japanese cool temperate forests that plays an important role in maintenance of the forest ecosystem and has high economic value. Here we assess the wide-range genetic structure of 23 natural populations of B. maximowicziana using 11 simple sequence repeat (SSR) loci. Genetic diversity within populations was relatively low in all populations (mean H(E), 0.361; mean allelic richness, 2.80; mean rare allelic richness, 1.02). The population differentiation was also relatively low (F(ST), 0.062). Genetic distance-based and Bayesian clustering analysis revealed that the populations examined here could be divided into a southern group and a northern group. Analysis of rare allelic richness and Bayesian clustering revealed evidence for both southern and northern refugia during the last glacial period. Furthermore, a comparison of regional genetic diversity revealed significant clines in allelic richness. In spatial genetic structure evaluation, significant isolation by distance (IBD) was detected among the 23 populations, but not within regions. Moreover, significant population bottlenecks were found in all populations under infinite allele model (IAM) assumptions. These unusual, significant bottlenecks might be because of the processes of postglacial colonization and the species' characters and/or life history as a long-lived pioneer tree species. The wide-range, regional genetic structure found in this study provides an important baseline for conservation and forest management, including the identification of evolutionarily significant units (ESUs) and/or management units (MUs) of B. maximowicziana.

Bayes Theorem↗
PubMed2004

Cataract in atomic bomb survivors.

PURPOSE: Ophthalmologic examinations were conducted on atomic bomb (A-bomb) survivors 55 years after exposure. MATERIALS AND METHODS: A-bomb survivors who had been exposed before 13 years of age at the time of the bombings in 1945 or who had been examined in a previous study between 1978 and 1980. The examinations, conducted between June 2000 and September 2002, included slit-lamp examination, digital photography and a cataract grading system for three parts of the lens (nucleus, cortex and posterior subcapsule) as an outcome variable. Proportional odds logistic regression analysis was conducted using the lowest grading class as a reference and included explanatory variables such as age, sex, city, dose and various cataract-related risk factors. When the grades in an individual differed, the worst grade was used. RESULTS: Results indicate that odds ratios (ORs) at 1 Sv were 1.07 (95% confidence intervals [CI] 0.90, 1.27) in nuclear colour, 1.12 (95% CI 0.94, 1.30) in nuclear cataract, 1.29 (95% CI 1.12, 1.49) in cortical cataract and 1.41 (95% CI 1.21, 1.64) in posterior subcapsular cataract. The same was true after excluding 13 people whose posterior subcapsular cataracts had been previously detected. CONCLUSION: Significant radiation effects were observed in two types of cataracts in A-bomb survivors.

Adolescent↗
PubMed2004

[The efficiency of nifekalant hydrochloride for the prevention of ventricular tachycardia during cardiac surgery].

Many cases have been successfully treated by us with experimented nifekalant hydrocholoride to prevent ventricular tachycardia (VT) during cardiac surgery. The 13 patients who underwent cardiac surgery at our hospital from 1999 to 2002 were retroactively given nifekalant hydrocholoride against VT. Lidocaine hydrochloride was not effective for VT, and it was difficult for 3 patients to be weaned for cardio-pulmonary bypass, while 6 patients needed aortic balloon pumping or percutaneous cardio-pulmonary support. Nifekalant hydrochloride suppressed VT induction in 9 patients (69.2%). Blood pressure and heart rate did not change, but QTc intervals were significantly increased with nifekalant hydrochloride (p < 0.005). Proarrhythmic events (Torsades de pointes) occurred in 2 patients, but none of the cases showed drug-induced worsening of cardiac function. Nifekalant hydrochloride is a class III antiarrhythmic drug that has been found to be effective against VT and ventricular fibrillation. While class I antiarrhythmic drugs are usually ineffective and induce severe heart failure, nifekalant hydrochloride can be effective.

Adult↗
PubMed2004

Tumor-suppressive activities by chemokines introduced into OV-HM cells using fiber-mutant adenovirus vectors.

In this study, fiber-mutant adenovirus vectors encoding chemokines, Ad-RGD-mCCL17, Ad-RGD-mCCL21 and Ad-RGD-mCCL22 were constructed. The insertion of integrin-targeting RGD sequence into fiber knob of adenovirus vectors notably enhanced the infection efficiency into tumor cells. Among three chemokine-encoding vectors evaluated, Ad-RGD-mCCL22 showed significant tumor-suppressive activity via transduction into OV-HM cells.

Adenoviridae↗
PubMed2004

[Mitral valve plasty and coronary artery bypass grafting under beating heart cardiopulmonary bypass for severe left ventricular dysfunction; report of a case].

A 54-year-old man with ischemic mitral regurgitation and severe heart failure due to broad myocardial infarction successfully underwent mitral valve plasty and coronary artery bypass grafting under beating heart. He had an old anterior myocardial infarction and was admitted to our hospital with acute inferior myocardial infarction. Two weeks later, the cathetelization revealed moderate mitral regurgitation and triple vessel coronary artery disease. We selected antegrade continuous blood perfusion for myocardial protection on operation. He recovered uneventfully and discharged on postoperative day 31. We could perform this procedure safety and satisfactorily, we could this procedure for heart valve operation with other complications.

Cardiac Surgical Procedures↗
PubMed2003

[Aortic valve replacement with a freestyle stentless valve using the modified subcoronary technique and hemiarch replacement for bicuspid aortic valve and ascending aortic aneurysma; report of a case].

An association between bicuspid aortic valve disease and ascending aortic aneurysma has long been recognized. Root replacement with a composite valve graft for such disease is a well-established technique. But it may involve serious technical difficulties, and may be a more time-consuming procedure than separate valve replacement and graft replacement. We performed an aortic valve replacement with Freestyle stentless valve using the modified subcoronary technique and hemiarch replacement for a 72-year-old man with severe aortic stenosis and ascending aortic aneurysma. Angiographic studies after surgery showed no residual aortic regurgitation (AR) and no deformity of aorta. This technique is an acceptable option for an aortic disease and ascending aneurysma in elderly patients.

Aged↗
PubMed2003

[Clinical outcome of emergency off-pump coronary artery bypass grafting].

From January 2001 to January 2003, we performed 25 emergency off-pump coronary artery bypass grafting (CABG) procedures for patients with acute myocardial infarction (AMI) or unstable angina pectoris. During the same period, we also performed 2 emergency on-pump beating CABG procedures for patients with left main coronary trunk (LMT) shock syndrome. For the present study, we evaluated the operative results of the 25 cases of emergency or urgent off-pump CABG. The patients were divided into 3 groups, those with acute AMI with cardiogenic shock (group 1; n = 8), acute myocardial infarction without shock (group 2; n = 8), and unstable angina (group 3; n = 9). There were no differences between groups 1 and 2 with regard to age, number of diseased vessels, and preoperative use of an intraaortic balloon pump, however, patients in group 1 had a higher number of completely obstructed coronary arteries. Patients in groups 1 and 2 underwent off-pump CABG within 3.5 hours after a coronary angiography or coronary intervention procedure, while those in group 3 underwent off-pump CABG within 2 days of coronary angiography. The mean number of grafts per patient was 1.8, 2.1, and 2.3 in groups 1, 2, and 3, respectively. One group 1 patient with an LMT lesion was transferred to on-pump beating CABG because of hemodynamic instability. The 30-day mortality rate was 38% (3 of 8) in group 1, whereas it was 0% in groups 2 and 3. Intubation time, ICU stay, and postoperative stay were similar among the 3 groups. An early angiographic study was undertaken in all surviving patients and the results demonstrated patency in all of the examined grafts. Although our results are limited, emergency off-pump CABG was found to be safe and feasible for AMI without cardiogenic shock or unstable myocardial ischemia. However, the outcome of this procedure for patients with preoperative cardiogenic shock was not satisfactory, therefore, a combination therapy of appropriate mechanical circulatory support, prior revascularization by catheter intervention, and emergency surgical revascularization are considered to improve survival of those patients.

Aged↗
PubMed2003

[Economic evaluation of off-pump coronary artery bypass grafting; compared to conventional coronary artery bypass grafting].

This study was undertaken to compare economic outcomes of off-pump coronary artery bypass grafting (off-pump CABG: OPCAB) and conventional CABG (CCABG). We reviewed the medical records of 5 patients with ischemic coronary disease (IHD) who underwent OPCAB and 5 patients with IHD who underwent CCABG. A hospital income which was based on a current Japanese health insurance system was indicated. There were significant differences in total cost (OPCAB = 208,200 +/- 7,383 yen versus CCABG = 324,300 +/- 10,290 yen, 35.8% decreased), costs of medical materials and transfusions (OPCAB = 14,760 +/- 3,270 yen versus CCABG = 87,540 +/- 3,326, 81.3% decreased) and charges of surgery and anesthesia (OPCAB = 130,400 +/- 1,853 yen versus CCABG = 147,650 +/- 4,167 yen, 12% decreased) OPCAB markedly reduces the cost of hospitalization. But charges of surgery and anesthesia of OPCAB seems to be valued properly in a current Japanese health insurance system.

Anesthesia↗
PubMed2003

[Apico-aortic conduit for severe aortic stenosis in elderly].

We described a case of an 84-year-old woman with end stage aortic stenosis in whom favorable results were obtained after constructing apico-aortic conduit bypass. The patient admitted due to complete atrio ventricular(AV) block and respiratory insufficiency. Although a permanent pacemaker was implanted, heart failure did not improve. Echocardiograms showed small aortic annulus and severe calcific aortic stenosis with a measured trans valve gradient of 100 mmHg. Since cardiac failure deteriorated and she lapsed into hypotension and acute renal failure, an emergency operation was performed. The left lateral thoracotomy was performed with cardiopulmonary bypass. A bioprosthetic valved conduit was anastmosed to the left ventricle apex. Another graft was anastomosed to the discending thoracic aorta. The operation was completed by anastomosing the tailored ends of the grafts together. Although the patient required hemodialysis for 2 weeks after operation, she was discharged on 57th day after operation without any complications. Apico-aortic conduit is considered to be an useful procedure for elderly patients who were not good candidates for conventional valve replacement.

Aged↗
PubMed2002

A laboratory and field evaluation of Macrocyclops distinctus, Megacyclops viridis and Mesocyclops pehpeiensis as control agents of the dengue vector Aedes albopictus in a peridomestic area in Nagasaki, Japan.

The use of the cyclopoid copepods Macrocyclops distinctus (Richard) Megacyclops viridis (Jurine) and Mesocyclops pehpeiensis Hu (Cyclopoida: Cyclopidae) as biological control agents against the dengue vector Aedes albopictus (Skuse) (Diptera: Culicidae) was evaluated. In the laboratory their predatory ability was highest against the younger instars of Ae. albopictus and none of the three copepods killed the fourth instar. Except for M. viridis, predatory ability was affected by the size of the container: the smaller the container, the higher the predation. A 4-month field test was conducted to examine the impact of these predators on wild Ae. albopictus. Thirty artificial containers were placed in a peridomestic area to allow Ae. albopictus colonization. We showed continuous and similar oviposition responses in treated and control containers. The densities of Ae. albopictus showed considerable short-term changes and were much reduced by the copepod species. Macrocyclops and the mixture of all three provided better Ae. albopictus control than either Megacyclops or Mesocyclops alone. When larval densities peaked in the control containers in August and September, the overall reduction due to the copepods was nearly complete. Mesocyclops inoculated alone had the highest population survival. However, the growth and survival of all the copepod species was poor when the three genera were mixed. Based on their performance and survival in the trial, Macrocyclops and Mesocyclops merit consideration as bio-control agents of Ae. albopictus.

Aedes↗
PubMed2002

[Graft holding system; a new device for coronary artery bypass grafting].

A new graft holding system for coronary artery bypass grafting was described. This system was an application of a memo-clip, which was composed of a flexible arm and 2 paper clips at both ends. A graft was wrapped by a piece of sponge and pinched indirectly by one of the clips. The other clip was fixed at an edge of the sternal retractor. Regardless of the size of the graft or the amount of the surrounding tissue, the graft can be fixed securely at one's pleased position due to a flexible arm of the device. Intimal injury can be avoided referring to the gentle holding of a piece of sponge. It enables us to place precise stitches and to minimize handling, anastomosis time, and leakage.

Anastomosis, Surgical↗
PubMed2001

Oral absorption of cephalosporins is quantitatively predicted from in vitro uptake into intestinal brush border membrane vesicles.

In order to establish a method to predict oral absorption of drugs, which are absorbed by the oligopeptide transporter (PepT1), fraction absorbed (F) of cephalosporin antibiotics was predicted from in vitro uptake into rat intestinal brush border membrane vesicles (BBMV). Using in vitro uptake data, F values of cephalosporins in humans were predicted using the equation derived from the complete radial mixing (CRM) model, which was proposed by Amidon et al. (Amidon et al., J. Pharm. Sci. 69 (1980) 1369). In the present study, uptake into BBMV was measured at 25 and 4 degrees C in the presence of an H+ -gradient, and the uptake clearance (CLuptake) was calculated. Clearance for the uptake mediated by PepT1 (DeltaCLuptake) was then calculated as CLuptake at 25 degrees C minus that at 4 degrees C. When DeltaCLuptake and F values were analyzed according to the present equation, fairly good correlation between DeltaCLuptake and F was observed. It was further demonstrated that the present method may be able to quantitatively predict F values of cephalosporins by using several cephalosporins as standards.

Absorption↗