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Biomedical subjects

T Shimasaki

Publications and source records attributed to T Shimasaki.

18 recordsLinked to original sources
PubMed2002

Induction of DNA double strand breaks in scid cells by carbon ions.

The DNA double strand breaks (DSBs) induced by X ray and carbon ion beam irradiation in scid cells were analysed using pulsed-field gel electrophoresis. Scid cells and hybrid cells were ideal to study the DNA DSB repair mechanisms, because their genetic backgrounds were identical except DNA-PK activity. Induction of DNA DSBs was determined after exposure to X rays and carbon beams. DNA DSB repair was by biphasic kinetics with a fast and a slow component. For scid cells only a slow component was observed, whereas the kinetics of DSBs repair was biphasic with a fast and a slow component. It was concluded from the experimental data that the induced DSB rejoining in scid cells was due to the lack of DNA-PK activity.

Carbon Radioisotopes↗
PubMed1999

Heat sensitivity of double-stranded DNA-dependent protein kinase (DNA-PK) activity.

PURPOSE: The heat sensitivity of DNA-PK activity in hybrid cells and the possible restoration of this activity with extracts from scid cells (defective in DNA-PKcs), sxi-3 cells (defective in Ku80) and V794 (sxi-3 parental wild-type cells) was analysed. MATERIALS AND METHODS: Heat treatment of cells was performed in a water bath at 44 degrees C. The cell extract from scid cells or sxi-3 cells was added to heat-treated hybrid cell extracts, and the DNA-PK activity was assayed. RESULTS: When hybrid cells were heated at 44 degrees C for 15 min, DNA-PK activity was reduced to undetectable levels. The decreased DNA-PK activity could be restored in a concentration-dependent manner with the addition of scid cell extract. The sxi-3 cell extract could not restore heat-inactivated DNA-PK activity. CONCLUSIONS: DNA-PK was inactivated by heat treatment at 44 degrees C. Ku70/Ku80, but not Ku70 alone, could restore heat-inactivated DNA-PK.

Animals↗
PubMed1995

[Antegrade or retrograde blood cardioplegic method: comparison of postsurgical right ventricular function and conduction disturbances].

This study was undertaken to compare postsurgical right ventricular function and the occurrence of conduction disturbances after employing cold blood antegrade or retrograde cardioplegia during open heart surgery. Thirty-four patients were divided into AC (antegrade) and RC (retrograde) groups for the difference of route for delivery of cardioplegic solutions. Preoperative evaluation of cardiac and respiratory function revealed to be equal characteristics between the groups. Postoperatively, A-aDO2 and respiratory index (RI) as functional parameters of oxygenation capacity, LVSWI, RVSWI, dosage of dopamine and conduction disturbances were monitored at 0, 3, 6, 12 hours after termination of cardiopulmonary bypass and at extubation period. Although the recovery of respiratory function and left ventricular function were similar in both groups, temporal suppression of right ventricular function was indicated in RC group during early period after surgery, and then recovered to the same values of AC group within 3 hours. In RC group, several type of conduction disturbances were detected in 28 per cent of patients. But none of the persistent conduction disturbances were remained in all patients. We suggest retrograde coronary sinus perfusion may emerge as a valuable alternative to antegrade methods for delivery of cardioplegia.

Blood↗
PubMed1995

[A case report on a reconstructive operation of a traumatic tricuspid regurgitation with a congenital defect of the left pericardium].

We reported a successful tricuspid valve replacement in a 58-years old man, who had easy fatiguability after 14 years of a blunt chest trauma. The preoperative examination revealed a marked cardiomegaly with deformation of both ventricles and grade 4 tricuspid regurgitation caused by the prolapse of the anterior leaflet. The operative inspection revealed a left pericardial defect with a diameter of 10 cm and a torn anterior papillary muscle. Since a usual plastic procedure did not improve the regurgitation, a Carpentier-Edward bioprosthetic valve was implanted in the supra annular position. Atrioventricular conduction was preserved. The tricuspid valve was not resected to preserve the ventricular function. The patient recovered his own activity.

Heart Injuries↗
PubMed1994

[Reoperations for complications after mechanical valve replacement].

Among 310 patients with mechanical valve replacement, 24 patients required reoperations for three types of complications; 12 disc immobilizations on 10 patients, 9 prosthetic valve endocarditis (PVE) on 8 patients and 8 perivalvular leakage or aortic pseudoaneurysm on 7 patients. Long-term survival was 71 percent for PVE and leakage, and 20 percent for emergency surgery of disc immobilization with mean follow up of 67 months. We suggest a few compromised patients with healed fungal endocarditis might show various types of prosthetic valve complications such as tissue ingrowth, late perivalvular leakage or pseudoaneurysmal formation.

Adolescent↗
PubMed1994

[A case of nontraumatic rupture of ascending aorta].

A 34-year-old man became shock caused by nontraumatic ascending aortic rupture. He was urgently operated. The aortic annulus was mildly ectatic and right coronary cusp was aneurysmal but not perforated. There was a small laceration in the anterior aortic wall without dissection. Cabrol operation was performed.

Adult↗
PubMed1993

Purification and some properties of intracellular alpha-L-arabinofuranosidase from Aspergillus niger 5-16.

alpha-L-Arabinofuranosidase was purified from a cell-free extract of Aspergillus niger 5-16 by chromatographies on DEAE-Toyopearl, SP-Toyopearl, Ultro-gel AcA 44, Mono P, and TSK-Gel G3000SW. The final preparation thus obtained showed a single band on SDS-polyacrylamide gel electrophoresis. The molecular weight and isoelectric point were 67,000 by SDS-polyacrylamide gel electrophoresis and pH 3.5 by isoelectric focusing. The alpha-L-arabinofuranosidase contained amino acids in the order of Asx > Gly > Ala > Thr > Glx = Ser. The enzyme had maximum activity at pH 4.0 and 60 degrees C, and was stable from pH 4 to 7 and at temperatures up to 30 degrees C. The enzyme activity was not affected considerably by either metal ions or chemical reagents. The enzyme released arabinose from p-nitrophenyl-alpha-L-arabinofuranoside, O-alpha-L-arabinofuranosyl-(1-->3)-O-beta-D-xylopyranosyl-(1-->4)-D- xylopyranose, and arabinan, but not from O-beta-D-xylopyranosyl-(1-->4)-O-[alpha-L-arabinofuranosyl- (1-->3)]-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose, O-beta-D-xylopyranosyl-(1-->2)-O-alpha-L-arabinofuranosyl-(1-->3)-O-beta -D- xylopyranosyl-(1-->4)-O-beta-D-xylopyranosyl-(1-->4)-D-xylopyranose, gum arabic, or arabinoxylan. The limit of hydrolysis of arabinan was about 58% even when the enzyme was sufficiently in excess.

Amino Acids↗
PubMed1993

[The relation between the time and the fatigue of skeletal muscle ventricle].

It is generally recognized that if skeletal muscle is stimulated corresponding with the heart rate to assist the cardiac performance, the contraction power of the skeletal muscle decreases in a few minutes. It becomes necessary that the skeletal muscle is electrically stimulated in 6-9 weeks to lead into the transformation or that the muscle is laid without working after operation in 6-9 weeks to wait for growing of the collateral vessels. The observation time of the fatigue phenomenon in many studies is, however, short and it is not understandable that the contraction power decreases near to zero although the type I fibers remain. So we studied the relationship between the time and the pressure assist of the skeletal muscle ventricle (SMV). It was concluded that 1) the cause of the power decrease is not only the fatigue but the operative invasion. 2) in our setting, when SMV was stimulated in the ratio of 1:4 or 1:10 to the heart rate, the power recovered within 3 hours. 3) if the initial setting of the drive is light enough, the preconditioning or the vascular delay will be unnecessary and the working transformation or the in situ training will practicable.

Animals↗
PubMed1993

[A hanger for thoracic surgery].

A new hanger for thoracic operation is introduced. This hanger for draping cloth is made for the purpose 1) of isolating the operative field from the anesthetist, 2) of keeping the broad hygienic area around the operator, 3) of keeping the area to handle the endotracheal tube for the anesthetist, 4) of keeping the area on the cranial side of the patient where the second assistant is able to stand, 5) of keeping the area for the watcher to stand.

Humans↗
PubMed1993

[Hygienic handling in cardiac surgery].

Some points regarding the hygienic handling in cardiac surgery are mentioned. The sternal infection or mediastinitis is still one of the most important complications after cardiac operation especially when ITA is used for CABG. After we paid much attention to these points, the postoperative sternal infection has decreased obviously.

Cardiac Surgical Procedures↗
PubMed1992

[A case of tricuspid pouch associated with ventricular septal defect and functional left ventricular-right atrial communication].

We reported a 60-year-old woman with tricuspid pouch associated with ventricular septal defect and subsequent left ventricular-right atrial communication. Preoperative angiographic findings suggested the presence of membranous septal aneurysm, ventricular and atrial septal defects, and tricuspid insufficiency. However, at operation, besides perimembranous inlet type ventricular septal defect, a pouch, 1.5 cm in diameter was found in the adjacent part to the septal leaflet within the anterior one of the tricuspid valve. The ventricular septal defect was closed with a patch. From these findings, it is speculated that the tricuspid pouch was formed by the effect of jet stream through the ventricular septal defect.

Diagnosis, Differential↗
PubMed1991

[Mechanical factors of a severe type of ventricular arrhythmia after Cabrol's operation].

Severe type of ventricular arrhythmia was noticed after Cabrol's operation more frequently than usual reperfusion arrhythmia. Nine patients received Cabrol's operation and 2 of Bentall's were divided into 2 groups according to the occurrence of postsurgical ventricular arrhythmia (Lown's classification grade 0-3: 5 cases, grade 4 A-5: 6 cases), and then the factors contributed to the arrhythmia were analyzed. There were no significant differences between the 2 groups on the point of the characteristics of the cases with or without emergent surgery for, such as ruptured or dissecting thoracic aortic aneurysms or other complicated lesions, the degree of surgical damage, or preoperative cardiac function. The only significant difference between the groups was the angle overheading to the central point of left coronary orifice anastomosed with intermediate tube from the extensive line of the prosthetic flange obtained in the left anterior oblique views on the angiography. The mean value of the angle of the severe group (grade 4 A-5) was 41 +/- 6.8 degrees (mean +/- SD) and significantly acute than the angle of the other group (grade 0-3: 57 +/- 6.4 degrees). This fact suggested that the main reason of the ventricular arrhythmia was coronary ischemia caused by compression of the intermediate tube after formation of massive hematoma within the aneurysmal capsule wrapped over the composite graft.

Adult↗
PubMed1990

Measurement of 239Pu in soil and plants in the Nishiyama District of Nagasaki.

Nishiyama district in Nagasaki is located approximately 3000 m east of the hypocenter of the atomic bomb that was dropped on 9 August 1945. This district is also known as an area where there was a concentrated radioactive fallout with the black rain that was carried by a westerly wind. The Nagasaki atomic bomb was a Pu bomb, and the fallout must have included 239Pu without fission in addition to fission products. The presence of 239Pu in Nishiyama district has been confirmed previously. In this study, the distribution of 239 + 240Pu concentration in the uncultivated soil and the transfer factor of 239 + 240Pu to agricultural products in Nishiyama district were examined. The concentration of 239 + 240Pu in the uncultivated soil was 20 Bq kg-1, which was approximately eight times as high as that in the control districts. The transfer factor of 239 + 240Pu to agricultural products was 10(-4) - 10(-3), which was 1/100-1/200 of that of 137Cs.

Agriculture↗
PubMed1990

[Transaortic myectomy for hypertrophic obstructive cardiomyopathy--efficacy of intraoperative pressure measurement].

The many aspects of postoperative course of hypertrophic obstructive cardiomyopathy (HOCM) have been apparent, while many studies concerning long-term follow up have been published in recent years. Many surgical approaches have been performed but recently transaortic subvalvular myectomy is most common. This study reviews 22 patients with HOCM operated on between 1984 and 1989. Transaortic approach was used for all adult patients. One patient had a complication with an iatrogenic VSD, which was closed by Dacron patch during the procedure. There was one hospital death; She is a 67 year-old woman who died due to an acute abdomen. All 14 patients followed up over 3 months had significant functional improvement. Our retrospective study suggests that myectomy in patient with HOCM seems to be not only palliative but curative operative method. Left atrial- and left ventricular dimension tended to normalize in the postoperative course. The intraoperative estimation of Brockenbrough phenomenon is effective to assess the release of left ventricular outflow obstruction.

Adult↗
PubMed1984

A new indirect method for measuring arteriovenous O2 content difference and cardiac output from O2 and CO2 concentrations by rebreathing air.

A new indirect method for measuring the arteriovenous O2 content difference (avDO2) was developed. The avDO2 was calculated by dividing the gradient of the CO2 dissociation curve by that of a gas exchange ratio against PCO2. The latter slope was obtained from O2 and CO2 concentrations in rebreathing air. The validity of the method was tested preliminarily in human subjects by comparing the cardiac output calculated from avDO2 and O2 uptake (VO2) with that measured hitherto by other authors, and then in dogs by comparing the calculated avDO2 with the measured value. In the dog experiments, the rebreathing was performed 7 times in each of 7 dogs. Immediately after the rebreathing arterial and mixed venous blood were sampled and analyzed for avDO2. For each rebreathing period the avDO2 was calculated by using the CO2 dissociation curve obtained in the individual dogs. The correlation coefficient between the measured and calculated avDO2 was 0.87, demonstrating reasonable validity of the method. The VO2 was further measured from the time interval during which a known amount of pure O2 was consumed. Then, the cardiac output was calculated by dividing the VO2 by the measured and calculated avDO2. The correlation coefficient between the respective cardiac output values was 0.88, indicating the reliability of using the calculated avDO2.

Animals↗