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T Kawata

Publications and source records attributed to T Kawata.

At least 55 records · Page 3Linked to original sources
PubMed2001

Analysis of histochemically and morphometrically in the anterior belly digastric muscle of osteopetrotic (op/op) mice.

The fibers of the anterior belly digastric muscle of mice, fed a granulated diet for various periods, have been studied histochemically and morphometrically. The diameters of the anterior belly digastric fibers in normal mice fed only a granulated diet were smaller than those in mice fed a solid diet. Differences in the succinate dehydrogenase (SDH) activity of muscle fibers between op/op and normal mice gradually appeared in the anterior belly digastric muscle and, by the age of 90 days, under-development of muscle fibers was observed in the mild-belly region of the anterior belly digastric muscle of op/op mice fed a granulated diet. These results indicate mechanical stress in mastication plays an important role in the development of the anterior belly digastric muscle structures.

Animals↗
PubMed2001

Comparison of F ratios generated from interphase and metaphase chromosome damage induced by high doses of low- and high-LET radiation.

Although biophysical models predict a difference in the ratio of interchromosomal to intrachromosomal interarm exchanges (F ratio) for low- and high-LET radiations, few experimental data support this prediction. However, the F ratios in experiments to date have been generated using data on chromosome aberrations in samples collected at the first postirradiation mitosis, which may not be indicative of the aberrations formed in interphase after exposure to high-LET radiations. In the present study, we exposed human lymphocytes in vitro to 2 and 5 Gy of gamma rays and 3 Gy of 1 GeV/nucleon iron ions (LET = 140 keV/micrometer), stimulated the cells to grow with phytohemagglutinin (PHA), and collected the condensed chromosomes after 48 h of incubation using both chemically induced premature chromosome condensation (PCC) and the conventional metaphase techniques. The PCC technique used here condenses chromosomes mostly in the G(2) phase of the cell cycle. The F ratio was calculated using data on asymmetrical chromosome aberrations in both the PCC and metaphase samples. It was found that the F ratios were similar for the samples irradiated with low- and high-LET radiation and collected at metaphase. However, for irradiated samples assayed by PCC, the F ratio was found to be 8.2 +/- 2.0 for 5 Gy gamma rays and 5.2 +/- 0.9 for 3 Gy iron ions. The distribution of the aberrations indicated that, in the PCC samples irradiated with iron ions, most of the centric rings occurred in spreads containing five or more asymmetrical aberrations. These heavily damaged cells, which were either less likely to reach mitosis or may reach mitosis at a later time, were responsible for the difference in the F ratios generated from interphase and metaphase analysis after exposure to iron ions.

Chromosome Aberrations↗
PubMed2001

Rejoining of isochromatid breaks induced by heavy ions in G2-phase normal human fibroblasts.

We reported previously that exposure of normal human fibroblasts in G2 phase of the cell cycle to high-LET radiation produces a much higher frequency of isochromatid breaks than exposure to gamma rays. We concluded that an increase in the production of isochromatid breaks is a signature of initial high-LET radiation-induced G2-phase damage. In this paper, we report the repair kinetics of isochromatid breaks induced by high-LET radiation in normal G2-phase human fibroblasts. Exponentially growing human fibroblasts (AG1522) were irradiated with gamma rays or energetic carbon (290 MeV/nucleon), silicon (490 MeV/nucleon), or iron (200 MeV/nucleon) ions. Prematurely condensed chromosomes were induced by calyculin A after different postirradiation incubation times ranging from 0 to 600 min. Chromosomes were stained with Giemsa, and aberrations were scored in cells at G2 phase. G2-phase fragments, the result of the induction of isochromatid breaks, decreased quickly with incubation time. The curve for the kinetics of the rejoining of chromatid-type breaks showed a slight upward curvature with time after exposure to 440 keV/microm iron particles, probably due to isochromatid-isochromatid break rejoining. The formation of chromatid exchanges after exposure to high-LET radiation therefore appears to be underestimated, because isochromatid-isochromatid exchanges cannot be detected. Increased induction of isochromatid breaks and rejoining of isochromatid breaks affect the overall kinetics of chromatid-type break rejoining after exposure to high-LET radiation.

Cells, Cultured↗
PubMed2001

Cell killing and mutation induction by heavy ion beams.

Carbon beam radiotherapy for cancer patients was initiated in Japan in June 1994. This study attempts to clarify the radiobiological effects of heavy ion beams. In this study, human cancer cell lines (RMG-1, MDA-MB231) and V79 cells were used. The cell killing was determined by colony forming assay, and mutation induction was determined by counting the number of 6-thioguanine resistant colonies (hprt locus mutation assay). The cell lines were irradiated with carbon (20 or 80 keV/microm) or neon beams (80 keV/microm). Carbon ions with a higher LET value (80 keV/microm) had an enhanced cytotoxic effect compared to those with a lower LET value (20 keV/microm). Carbon beams produced a slightly stronger cytotoxic effect than neon beams when irradiated at the same LET level (80 keV/microm), but the difference was not remarkable. The mutant fraction was significantly higher in all cell lines when they were irradiated with heavy ion beams, compared to the results for X-ray irradiation. The mutant fraction increased when the LET of the carbon beams increased. At equivalent LET values, the mutant fraction was lower for neon beams than for carbon beams. Fractionation of carbon beam irradiation had no effect on survival, but reduced the mutant fraction. Neon beams might be more appropriate for heavy ion therapy, especially when higher doses are being used. In addition, the fractionation of heavy ion beam administration might be appropriate for reducing the mutant fraction.

Animals↗
PubMed2001

Differences in adaptation to growth of children between internal thoracic artery and saphenous vein coronary bypass grafts.

BACKGROUND: It is not known how the internal thoracic artery (ITA) and saphenous vein graft (SVG) adapts to somatic growth of pediatric patients who underwent coronary artery bypass grafting (CABG). METHODS: Twenty-two ITAs and 6 SVGs in 17 patients who underwent at least three postoperative catheterizations with biplanar cineangiography and followed for a minimum of 5 years were evaluated. We evaluated the length, diameter and curvature of the grafts by cineangiographies which were performed at 1 month, 1 year, 5 years and more than 5 years postoperatively. RESULTS: The length of the ITA (1-month: 117+/-31 mm, 1-year: 134+/-32 mm, 5-years: 146+/-28 mm, and >5-years: 155+/-34 mm, p=0.032) and diameter of the ITA (1.4+/-0.4 mm, 2.0+/-0.7 mm, 2.3+/-0.6 mm and 2.6+/-0.6 mm, p<0.0001) significantly increased over time, but neither the length nor diameter of the SVG length: 121+/-33 mm, 119+/-29 mm, 119+/-25 mm and 126+/-1 mm, p=0.9907; diameter: 4.1+/-1.0 mm, 3.9+/-0.7 mm, 4.0+/-0.8 mm and 3.3+/-0.4 mm, p=0.5784) increased. Although the ITA exhibited no change in curvature over time (1 month: 1.15+/-0.07, late: 1.15+/-0.07, p=0.8490), the curvature of the SVG significantly decreased over time (1 month: 1.42+/-0.19 and late: 1.25+/-0.16, p=0.0277). The percent segmental length of ITAs were changed little from early to late after CABG (1 month: proximal: 33.7+/-7.0%, middle: 33.3+/-7.9% and distal: 32.9+/-7.9%, vs late: 34.3+/-7.2%, 33.2+/-7.9% and 32.5+/-7.9%, p=0.937). CONCLUSIONS: ITAs grow in proportion to somatic growth, while SVGs course in a more linear fashion in adapting to patient growth.

Adaptation, Physiological↗
PubMed2001

[Off-pump coronary artery bypass using bilateral in situ internal thoracic artery grafts for left coronary artery system: a case report].

A 63-year-old man with triple vessel disease in the coronary artery and multiple arterial stenoses in intra-cranial vessels underwent off-pump coronary artery bypass (OPCAB). We were able to perform three coronary artery bypass grafting (in situ left internal thoracic artery (left ITA)--left anterior descending artery, in situ right ITA--circumflex artery through the transverse sinus, and saphenous vein graft--right coronary artery) using octopus 2 and "Lima" suture technique without cardio-pulmonary bypass. Operation time was 355 minutes and established blood loss was 440 ml. Postoperative course was uneventful. Postoperative angiogram revealed well patent three grafts. Using bilateral in situ ITAs OPCAB could achieve high quality.

Coronary Artery Bypass↗
PubMed2001

Functional and perfusional assessment with electrocardiograph-gated single photon emission computed tomography after minimally invasive direct coronary artery bypass grafting.

BACKGROUND: Because of limited surgical field, minimally invasive coronary artery bypass grafting (MIDCAB) requires anastomosis to the distal portion of the left anterior descending artery (LAD) of the left internal thoracic artery (LITA) with the heart beating. Though the diameters of these arteries are very small, it is unknown whether blood flow sufficient for the LAD territory is obtained by bypass grafting. METHOD: Eight patients with single-vessel disease of the LAD underwent MIDCAB with the LITA to the LAD and we evaluate the perfusion and function in the LAD territory by quantitative ECG-gated SPECT (QGS) with 99m-technetium sestamibi (MIBI) before and after operation. RESULT: The intraoperatively measured diameters of the LITA and LAD at the site of anastomosis were 1.1+/-0.2 mm and 1.3+/-0.4 mm, respectively. The percentage increases in end-diastolic perfusion, regional ejection fraction and regional wall thickening in the anteroseptal area after MIDCAB were 136.3+/-11.7(p=0.071), 148.4+/-6.6(p=0.007) and 133.0+/-5.6(p=0.029), respectively (paired t-test, mean +/- SD %). Stress-rest MIBI SPECT indicated no ischemia in anteroseptal wall. CONCLUSION: The MIDCAB technique thus appeared to improve perfusion and function in the LAD territory despite bypass to the distal LAD, and ECG-gated MIBI SPECT using QGS software was very useful for evaluating the quality of anastomosis after MIDCAB.

Aged↗
PubMed2001

[Edge to edge repair for mitral regurgitation in a patient with chronic hemodialysis: report of a case].

In a patient with chronic hemodialysis, the high risk of calcific degeneration of biological prosthetic valve and anticoagulant related complications after valve replacement have been reported. A 71-year-old woman with hemodialysis underwent the edge to edge repair combined with ring-annuloplasty for mitral regurgitation caused by the anterior leaflet prolapse without any torn chordae. Postoperative course was uneventful. There was no significant mitral regurgitation. Double mitral orifices were confirmed by the postoperative echocardiography. A calculated functional mitral valve area was 3.06 cm2. The edge to edge repair is a simplified technique and carried out in a short time. We believe the edge to edge repair is a useful technique for anterior mitral valve prolapse in a patient with chronic hemodialysis.

Aged↗
PubMed2001

Kinetics of chromatid break repair in G2-human fibroblasts exposed to low- and high-LET radiations.

The purpose of this study is to determine the kinetics of chromatid break rejoining following exposure to radiations of different quality. Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (290 MeV/u), silicon (490 MeV/u) and iron (200 MeV/u, 600 MeV/u). Chromosomes were prematurely condensed using calyculin A. Prematurely condensed chromosomes were collected after several post-irradiation incubation times, ranging from 5 to 600 minutes, and the number of chromatid breaks and exchanges in G2 cells were scored. The relative biological effectiveness (RBE) for initial chromatid breaks per unit dose showed LET dependency having a peak at 55 keV/micrometers silicon (2.4) or 80 keV/micrometers carbon particles (2.4) and then decreased with increasing LET. The kinetics of chromatid break rejoining following low- or high-LET irradiation consisted of two exponential components. Chromatid breaks decreased rapidly after exposure, and then continued to decrease at a slower rate. The rejoining kinetics was similar for exposure to each type of radiation, although the rate of unrejoined breaks was higher for high-LET radiation. Chromatid exchanges were also formed quickly.

Cell Line↗
PubMed2000

X-rays vs. carbon-ion tumor therapy: cytogenetic damage in lymphocytes.

PURPOSE: To measure chromosomal aberrations in peripheral blood lymphocytes from cancer patients treated with X-rays or carbon ions (C-ions). METHODS AND MATERIALS: Blood samples from patients diagnosed for esophageal or uterine cervical cancer were obtained before, during, and at the end of the radiation treatment. The novel technique of interphase chromosome painting was used to detect aberrations in prematurely condensed chromosomes 2 and 4. The fraction of aberrant lymphocytes was measured as a function of the dose to the tumor volume. For comparison, blood samples were also exposed in vitro to X-rays or to carbon ions accelerated at the HIMAC. RESULTS: C-ions were more efficient than X-rays in the induction of chromosomal aberrations in vitro. In patients with similar pathologies, tumor positions, and radiation field sizes, however, C-ions induced a lower fraction of aberrant lymphocytes than X-rays during the treatment. The initial slope of the dose-response curve for the induction of chromosomal aberrations during the treatment was correlated to the relative decrease in the number of white blood cells and lymphocytes during the treatment. CONCLUSION: C-ions induce a lower level of cytogenetic damage in lymphocytes than X-rays, reducing the risk of bone marrow morbidity.

Aged↗
PubMed2000

Complex-type chromosomal exchanges in blood lymphocytes during radiation therapy correlate with acute toxicity.

The new method of chemical-induced premature chromosome condensation combined with fluorescence in situ hybridization was used to analyze chromosomal damage in peripheral blood mononuclear lymphocytes of patients undergoing radiation treatment for esophageal cancer with high-energy X-rays or accelerated carbon ions at the National Institute of Radiological Sciences (Chiba, Japan). Total number of aberrant cells correlated with radiation field size, but no correlation was found with acute toxicity. A high frequency of complex-type exchanges were also recorded. This aberration type presented a high individual variability, and correlated well with the acute morbidity. Cytogenetic analysis by interphase chromosome painting is proposed as a useful tool for monitoring normal tissue effects during radiotherapy.

Aged↗
PubMed2000

Results from coronary artery bypass surgery combined abdominal aortic aneurysm repair.

OBJECTIVE: Complication from coronary artery disease is a major cause of mortality and morbidity in patients undergoing abdominal aortic aneurysm repair. We report our results from coronary artery bypass surgery performed in combination with abdominal aortic aneurysm repair in patients with coronary artery disease and abdominal aortic aneurysm, each being an indication for an emergency operation. METHODS: Seventeen patients underwent combined coronary artery bypass surgery and abdominal aortic aneurysm repair. The mean age of the patients was 67.6 +/- 5.2 years. Four had left main disease, 8 patients had triple-vessel disease, and 12 had a prior myocardial infarction. The average left ventricular ejection fraction was 0.49 +/- 0.13. The average abdominal aortic aneurysm diameter was 6.2 +/- 1.0 cm (range 4.5-8.0 cm). Thirteen patients underwent coronary artery bypass surgery followed by abdominal aortic aneurysm repair after discontinuation of cardiopulmonary bypass. In the remaining four patients, including one patient with severe left ventricular dysfunction, cardiopulmonary bypass was continued as a circulatory assist until the abdominal aortic aneurysm repair was completed. The left internal thoracic artery was used in 14 patients, and the right internal thoracic artery in one patient. RESULTS: Postoperative surgical complications occurred in three patients (bleeding in one patient requiring reoperation, abdominal subcutaneous wound infection in another and transient neural disorder in the others). There were no surgical or in-hospital death. There was no late cardiac complication and no late cardiac death after a mean of 29 months follow-up. CONCLUSIONS: We concluded that combined surgery was reasonable for selected patients with combined coronary artery disease and abdominal aortic aneurysm, each of which is an indication for an urgent operation. The aortic aneurysm repair during cardiopulmonary bypass for patients with severe left ventricular dysfunction was safe and effective.

Aged↗
PubMed2000

In vivo gene gun-mediated transduction into rat heart with Epstein-Barr virus-based episomal vectors.

BACKGROUND: Gene guns have been used to transfer genes into various organs, but there has been no report of successful gene gun-mediated gene transfer into the heart. In this study, we assessed the possibility of gene therapy using a gene gun and an episomal plasmid vector. METHODS: Gene transfer was performed using two sizes of gold particles and two plasmids (an episomal vector and a conventional plasmid vector). From the first to eighth week after the bombardment, rats were sacrificed. The excised hearts were subjected to X-gal staining and histologic examination. To ensure that plasmid was not distributed to organs other than the heart, the presence of the beta-gal sequence was examined by polymerase chain reaction analyses. RESULTS: Gene expression persisted for 6 weeks. The episomal vector apparently contributed to long-lasting expression. Infiltration of monocytes or leukocytes was very faint. The beta-gal DNA was detected in bombarded hearts but not other organs. CONCLUSIONS: Gene gun-mediated transfer of the episomal vector into beating heart may provide a simple, efficient, and useful strategy for gene therapy.

Animals↗
PubMed2000

Effects of insulin-like growth factor-I on nasopremaxillary growth under different masticatory loadings in growing mice.

It is well accepted that reduced masticatory function induced by a diet with soft physical consistency causes alterations in the craniofacial morphology in growing animals. It is assumed that these alterations are associated with reduced proliferative activity of osteoblasts on the bone surface, indicating a significant role for mechanical stimuli mediated by various local growth factors including insulin-like growth factor-I (IGF-I). Here, the effects of IGF-I on the linear growth of nasal and premaxillary bones subjected to different masticatory loadings were examined. The length of the nasal bone and the width of the premaxilla were measured. These dimensions were significantly greater in mice fed a solid diet than in mice fed a granulated diet. In animals treated with IGF-I, the nasal bone length and premaxillary width increased significantly in a subgroup receiving a solid diet, but these changes were not found in a similar group fed a granulated diet. No statistically significant differences in these dimensions were found between solid-diet mice injected with saline and granulated-diet group injected with IGF-I. It is concluded that IGF-I induces nasal and premaxillary growth, and that its effect is enhanced or accelerated by increased mechanical masticatory loading.

Analysis of Variance↗
PubMed2000

Changes in CD4+CD8-/CD4-CD8+ ratio and humoral immune functions in vitamin B12-deficient rats.

To clarify the role of vitamin B12 in the function of cell-mediated and humoral immune functions, the splenocytes expression of CD4, CD8 and serum C3, IgM, IgG concentrations were examined in vitamin B12-deficient rats, and the effect of the administration of methylcobalamin was also studied. The CD4+CD8-/CD4-CD8+ ratio in splenocytes was significantly higher in vitamin B12-deficient rats than in control rats (p < 0.05). The value in the 48 hours after methylcobalamin administration group, was within the normal range (p < 0.05). From these results, the elevation of the CD4+CD8-/CD4-CD8+ ratio by vitamin B12-deficiency was confirmed in rats. The serum C3, IgM and IgG concentrations were lower in the vitamin B12-deficient group than in the control group. These findings suggest that vitamin B12 plays a role in maintaining the immune function in rats.

Animals↗