Biomedical subjects

T Shirai

Publications and source records attributed to T Shirai.

At least 19 recordsLinked to original sources

PubMed2006

Mental fatigue-induced decrease in levels of several plasma amino acids.

To investigate the relation between plasma amino acid levels and mental fatigue, we measured the plasma concentrations of 20 amino acids in 9 healthy volunteers before and after a fatigue-inducing mental task session for 8 hr. As fatigue-inducing mental tasks, the subjects performed an advanced trail making test, a Japanese KANA pick up test, and a mirror drawing test. As a control, 8-hr relaxation session was performed in the same subjects at an interval of 4 weeks. Immediately after the fatigue session, the plasma levels of branched-chain amino acids, tyrosine, cysteine, methionine, lysine, and arginine were below those after a relaxation session. The values for other blood parameters including total protein, albumin, glucose, and total cholesterol did not show any differences between the 2 sessions. These results indicate that mental fatigue may be characterized by a decrease in the plasma level of these amino acids.

Adult↗

PubMed2006

Anisotropy and corotation of galactic cosmic rays.

The intensity of Galactic cosmic rays is nearly isotropic because of the influence of magnetic fields in the Milky Way. Here, we present two-dimensional high-precision anisotropy measurement for energies from a few to several hundred teraelectronvolts (TeV), using the large data sample of the Tibet Air Shower Arrays. Besides revealing finer details of the known anisotropies, a new component of Galactic cosmic ray anisotropy in sidereal time is uncovered around the Cygnus region direction. For cosmic-ray energies up to a few hundred TeV, all components of anisotropies fade away, showing a corotation of Galactic cosmic rays with the local Galactic magnetic environment. These results have broad implications for a comprehensive understanding of cosmic rays, supernovae, magnetic fields, and heliospheric and Galactic dynamic environments.

Journal Article↗

PubMed2006

Genetic control of the spontaneous activation of CD4+ Th cells in systemic lupus erythematosus-prone (NZB x NZW) F1 mice.

The F(1) hybrid of autoimmune hemolytic anemia-prone NZB and nonautoimmune NZW strains of mice has been studied as a murine model of systemic lupus erythematosus. Both NZB and F(1) hybrid mice show age-dependent spontaneous activation of peripheral CD4(+) T cells as reflected by the elevated frequencies of CD4(+) T cells positive for CD69 early activation marker. Both strains also show age-dependent abnormal decrease of the frequencies of CD62L(+) naive CD4(+) T cells and/or NTA260(+) memory CD4(+) T cells in the spleen. We studied the multigenic control of these abnormal features of peripheral CD4(+) T cells in (NZB x NZW) F(1) x NZW backcross mice by quantitative trait loci mapping and by association rule analysis. The abnormally elevated frequencies of CD69(+)CD4(+) T cells and decreased frequencies of CD62L(+) naive and/or NTA260(+) memory CD4(+) T cells were under the common genetic control, in which the interaction between MHC and a hitherto unknown locus, designated Sta-1 (spontaneous T-cell activation) on chromosome 12, plays a major role. The allelic effects of these loci likely predispose CD4(+) T cells to the loss of self-tolerance, and are responsible for the accelerated autoimmune phenotypes of (NZB x NZW) F(1) hybrid mice.

Age Factors↗

PubMed2006

[Emergent coronary artery bypass grafting for a patient with cardiopulmonary arrest].

A 59-year-old man was admitted to our hospital due to sudden onset of unconsciousness caused by myocardial infarction with ventricular fibrillation. Emergent coronary angiography under intraaortic balloon pumping revealed 90% stenosis of the left main trunk and left anterior descending artery (LAD), and complete obstruction of the left circumflex artery (Cx) and right coronary artery (RCA). Emergent coronary artery bypass grafting (CABG) to LAD, Cx, and RCA was performed. During the postoperative course, the patient developed ventricular tachycardia/fibrillation. After implantation of an implantable cardioverter defibrillator (ICD), he was discharged on the postoperative day 36. The patient has now resumed normal daily life.

Coronary Artery Bypass↗

PubMed2006

[Aortic regurgitation caused by rupture of a fibrous strand; report of a case].

Rupture of a fibrous strand of a tricuspid aortic valve is extremely rare. We describe a patient with aortic regurgitation due to spontaneous rupture of the fibrous strands that suspend the aortic valve leaflets. The fibrous strands were recognized between the left and right coronary cusps, and between the left coronary and non-coronary cusps during the operation. The fibrous strand between the left coronary and non-coronary cusps had been ruptured, and thus the left coronary and non-coronary cusps were prolapsed into the left ventricle. Since a degenerative change was observed histologically in the resected specimen, these fibrous strands were considered to be an embryonic remnant of the aortic valve.

Aged↗

PubMed2005

A ninety-day oral toxicity study of a new type of processed gum arabic, from Acacia tree (Acacia senegal) exudates, in F344 rats.

This study was designed to evaluate and characterize any subchronic toxicity of a new type of gum arabic (SUPER GUM [Acacia(sen)SUPER GUM]), a naturally processed polysaccharide exudate from gum acacia trees (Acacia senegal), when administered to both sexes of F344 rats at dietary levels of 0 (control), 1.25%, 2.5%, and 5.0% (10 rats/sex/group). During the study, the treatment had no effects on clinical signs, survival, body weights, and food and water consumption, or on findings of urinalysis, ophthalmology, hematology, or blood biochemistry. Gross pathology and histopathology exhibited no differences of toxicological significance between control and treated rats. Increased relative cecum (filled) weights, evident in both sexes of 5.0% group and females of 1.25% and 2.5% groups, were considered to be a physiological adaptation. Thus, the results indicated the toxic level of SUPER GUM to be more than 5.0%, and the no observed adverse effect level (NOAEL) was concluded to be 5.0% (3,117 mg/kg body weights/day for males, and 3,296 mg/kg body weights/day for males) from the present study.

Administration, Oral↗

PubMed2005

A 90-day oral toxicity study of beta-carotene derived from Blakeslea trispora, a natural food colorant, in F344 rats.

A subchronic oral toxicity study of beta-carotene derived from Blakeslea trispora, a natural food colorant, was performed with groups of 10 male and 10 female F344 rats fed the agent at dietary levels of 0%, 0.2%, 1.0% and 5.0% for 90 days. There were no treatment-related adverse effects with regard to body weight, food and water consumption, urinalysis, ophthalmology, hematology, serum biochemistry, and organ weight data. On clinical observation, red coloring of fur was noted in both sexes of the 1.0% and 5.0% group rats, with red feces observed in all treated group animals, and necropsy revealed all rats of the treated groups to have reddish coloration of the contents of the gastro-intestinal tract, due to the pigmentation and thus lacking toxicological significance. On histopathological examination, sporadic spontaneous lesions known to occur in this strain of rats were the only findings, with no specific relation to the test substance. Thus, the no-observed-adverse-effect-level (NOAEL) was judged to be a dietary level of at least 5.0% (3127 mg/kg body weight/day for males, 3362 mg/kg body weight/day for females) for beta-carotene derived from B. trispora under the present experimental conditions.

Animals↗

PubMed2005

Thirteen-week feeding study of thaumatin (a natural proteinaceous sweetener), sterilized by electron beam irradiation, in Sprague-Dawley rats.

This study was designed to evaluate and characterize any subchronic toxicity of thaumatin sterilized by electron beam irradiation (5.0 kGy) when administered at dietary levels of 0% (control), 0.3%, 1.0% and 3.0% to groups of 10 male and 10 female Crj: CD (SD) IGS rats for 13 weeks. Separate groups of both sexes received 3.0% non-irradiated thaumatin. There were no treatment-related clinical signs or adverse effects on the survival rate, body weight, food consumption, water consumption and urinalysis, ophthalmology, haematology, or blood biochemistry data. No treatment-related alterations in gross pathology or organ weights were found in any group. On histopathological examination, sporadic spontaneous lesions known to occur in this strain of rats were the only findings, with no specific relation to the test substance. Thus, the no-observed-adverse-effect-level (NOAEL) was judged to be a dietary level of at least 3.0% (2502 mg/kg body weight/day for males, 2889 mg/kg body weight/day for females) for electron beam irradiated thaumatin under the present experimental conditions. It was concluded that electron beam-irradiation of thaumatin does not cause changes of any toxicological significance.

Administration, Oral↗

PubMed2005

[Reoperative off-pump coronary artery bypass via left thoracotomy with porcelain aorta; left axillary artery to circumflex artery bypass; report of a case].

A 62-year-old man who underwent coronary artery bypass grafting (CABG) [left internal thoracic artery (LITA)-left anterior descending (LAD), saphenous vein graft (SVG) right coronary artery (RCA)] 13 years previously developed angina pectoris and congestive heart failure because of occlusion of SVG and native vessels. Coronary angiography (CAG) revealed that inflow to the coronary artery remained only from LITA. Repeat off-pump CABG (OPCAB) with SVG to the circumflex artery via left thoracotomy was performed. The proximal end of SVG was anastomosed to the left axillary artery because of the porcelain aorta and the patent LITA graft. The patient developed no complications and was discharged from hospital on postoperative day 21. OPCAB for circumflex artery by left thoracotomy is an effective and safe approach in redo CABG, particularly in instances of patent LITA.

Aorta↗

PubMed2005

Breath alcohol concentrations in Japanese outpatients following paclitaxel and docetaxel infusion.

Patients receiving paclitaxel or docetaxel also receive a significant amount of ethanol, as both products contain ethanol as solvent. Patients in our clinics have occasionally exhibited signs of alcohol intoxication immediately after paclitaxel infusion. In 2002, the Japanese government lowered the minimum ethanol concentration for the definition of drunk driving, with the threshold breath alcohol concentration (BRAC) of 0.15 mg/l. The aim of this study was to measure BRAC in Japanese outpatients treated with paclitaxel or docetaxel and to assess intoxication according to this standard. Fifty-two Japanese patients were enrolled from October 2003 to February 2004. Patient characteristics were as follows: male/female, 13/39: median age, 71 (range: 34-78); breast/lung/ovarian cancer 24/16/12; and paclitaxel/docetaxel treatment: 36/16, respectively. The mean total doses of paclitaxel or docetaxel were 178 mg (range: 107-300) and 53 mg (30-100), respectively. Breath samples were measured three times immediately following the infusion of paclitaxel or docetaxel via ethyl alcohol detector and the mean value was recorded. BRAC was detected in 20 patients (56%) with paclitaxel and in none of the docetaxel patients. BRAC was measured again 30 min after the initial measurement in BRAC-detected cases with the patients' permission. In four of six BRAC-remeasured patients, BRAC became undetectable after 30 min. There was no correlation between the total doses of paclitaxel and BRAC or between the infusion rates of paclitaxel and BRAC. In conclusion, clinicians should recognize the potential for alcohol intoxication with paclitaxel administration. Patients should be instructed to avoid driving on the day of paclitaxel administration.

Adult↗

PubMed2004

Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun.

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.

Journal Article↗

PubMed2004

The use of ACORN in solving a 39.5 kDa macromolecule with 1.9 A resolution laboratory source data.

Data from the alkaline cellulase apo form were collected at a resolution of 1.9 A using an in-house X-ray source (Cu K alpha). By using different fragments of helices from the model solved by macromolecular crystallographic means, the direct-methods program ACORN was used to arrive at the complete model. Attempts have been made to use various percentages of input phasing information from these helices. The minimum input phasing required in feeding the fragments was about 14% of the whole structure. The phases obtained from ACORN were of superb quality, allowing automated model building to be carried out using ARP/wARP. Minimal manual model building was required and the structure determination was completed using the maximum-likelihood refinement program REFMAC. The whole process, starting from the running of ACORN and ending with the refined model, took nearly 15 h of CPU time using a Pentium III PC.

Algorithms↗

PubMed2004

Optimal control of ultrafast selection.

Optimal laser control for ultrafast selection of closely lying excited states whose energy separation is smaller than the laser bandwidth is reported on the two-photon transition of atomic cesium; Cs(6S-->7D(J), J=5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yields. After fifty generations, a pair of nearly transform-limited pulses were obtained as an optimal pulse shape, proving the effectiveness of the "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by approximately 30% from the simple "Ramsey fringes" experiment.

Journal Article↗

PubMed2004

Existence of a threshold for induction of aberrant crypt foci in the rat colon with low doses of 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine.

Until recently it has been generally considered that genotoxic carcinogens have no threshold in exerting their potential for cancer induction. However, the nonthreshold theory can be challenged with regard to assessment of cancer risk to humans. In the present study we show that a food derived, genotoxic hepatocarcinogen, 2-amino-1-methyl-6-phenolimidazo[4,5-b]pyridine (PhIP), does not induce aberrant crypt foci (ACF) as preneoplastic lesions at low dose (below 50 ppm) or 8-hydroxy-2'-deoxyguanosine (below 400 ppm) in the rat colon. Moreover PhIP-DNA adducts were not formed at the lowest dose (below 0.01 ppm). Thus, the dose required to initiate ACF is approximately 5000 times higher than that needed for adduct formation. The results imply a no-observed effect level (existence of a threshold) for colon carcinogenesis by a genotoxic carcinogen.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2004

A patient with TSC1 germline mutation whose clinical phenotype was limited to lymphangioleiomyomatosis.

BACKGROUND: Lymphangioleiomyomatosis (LAM) can occur as in isolated form (sporadic LAM) or as a pulmonary manifestation of tuberous sclerosis complex (TSC) (TSC-associated LAM). Recent studies, however, revealed that both forms of LAM are genetically related but that sporadic LAM is a distinct clinical entity caused by somatic mutations of TSC2 (not TSC1) rather than a forme fruste of TSC carrying either of the TSC1 or TSC2 germline mutations. METHOD: Case presentation and in-depth molecular and histopathological examinations. A 34-year-old Japanese woman was diagnosed as having pulmonary lymphangioleiomyomatosis (LAM) when bilateral pneumothoraces were surgically treated in 1992. Although slowly progressive renal disfunction was observed due to bilateral multiple renal cysts during the past 4 years, she had no other clinical features of TSC and was diagnosed as having sporadic LAM with multiple renal cysts of undetermined aetiology. Her subsequent clinical course was complicated by an endobrochial carcinoid tumour, which eventually resulted in her death in June 1999 due to massive haemoptysis. RESULTS: Postmortem examination revealed the presence of LAM lesions in the lungs, mediastinal lymph nodes, kidneys and uterus. Diffuse renal LAM lesions are presumed to generate multiple renal cysts by constricting the nephron rather than epithelial hyperplasia obstructing lumina, which is analysis of the TSC genes demonstrated that she did not have TSC2/PKD1 contiguous gene syndrome but had a TSC1 germline mutation (Sato T et al. J Hum Genet 2002; 47: 20-8) that had occured de novo. CONCLUSION: This patient therefore illustrates that clinical manifestations of TSC are sufficiently diverse as to allow a forme fruste of TSC that mimics sporadic LAM and that TSC1 mutation can cause multiple renal cysts resulting in renal failure.

Adult↗

PubMed2003

Applications of ACORN to data at 1.45 A resolution.

One of the main interests in the molecular biosciences is in understanding structure-function relations and X-ray crystallography plays a major role in this. ACORN can be used as a comprehensive and efficient phasing procedure for the determination of protein structures when atomic resolution data are available. An initial model can automatically be built by ARP/wARP followed by REFMAC for refinement. The alpha helices and beta sheets occurring in many protein structures can be taken as starting fragments for structure solution in ACORN. ACORN, along with ARP/wARP followed by REFMAC, can be an ab initio method for solving protein structure for which data are better than 1.2 A (atomic resolution). Attempts are here made in extending its applications to real data at 1.45 A resolution and also to truncated data at 1.6 A resolution. Two previously known structures, congerin II and alkaline cellulase N257, were resolved using the above approach. Automatic structure solution, phasing and refinement for real data at still lower resolutions for proteins of various complexities are being carried out. Data mining of the secondary structural features using PDB is being carried out for this new approach for 'seed-phasing' to ACORN.

Algorithms↗

PubMed2003

Energetic protons from a few-micron metallic foil evaporated by an intense laser pulse.

With detailed experimental studies and hydrodynamics and particle-in-cell simulations we investigate the role of the prepulse in laser proton acceleration. The prepulse or pedestal (amplified spontaneous emission) can completely evaporate the irradiated region of a sufficiently thin foil; therefore, the main part of the laser pulse interacts with an underdense plasma. The multiparametric particle-in-cell simulations demonstrate that the main pulse generates the quasistatic magnetic field, which in its turn produces the long-lived charge separation electrostatic field, accelerating the ions.

Journal Article↗

PubMed2003

A thirteen-week oral toxicity study of annatto extract (norbixin), a natural food color extracted from the seed coat of annatto (Bixa orellana L.), in Sprague-Dawley rats.

A subchronic oral toxicity study of annatto extract (norbixin), a natural food color, was conducted. Groups of 10 male and 10 female Sprague-Dawley rats were fed annatto extract at dietary levels of 0, 0.1, 0.3 and 0.9% for 13 weeks. There were no treatment-related adverse effects on body weight, food and water consumption, ophthalmology and hematology data. Blood biochemical analysis revealed changes in rats of both sexes confined to the 0.9% and 0.3% groups, including increased alkaline phosphatase, phospholipid, total protein, albumin and albumin/globulin ratio. Marked elevation in absolute and relative liver weights was also found in both sexes of the 0.9% and 0.3% groups, but not the 0.1% group. Hepatocyte hypertrophy was evident and an additional electron microscopic examination demonstrated this to be linked to abundant mitochondria after exposure to a dietary level of 0.9% annatto extract for 2 weeks. Thus, the No-Observed-Adverse-Effect-Level (NOAEL) was judged to be a dietary level of 0.1% (69 mg/kg body weight/day for males, 76 mg/kg body weight/day for females) of annatto extract (norbixin) under the present experimental conditions.

Administration, Oral↗