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Biomedical subjects

T Katsumata

Publications and source records attributed to T Katsumata.

At least 55 records · Page 3Linked to original sources
PubMed1999

Cell kinetics, p53 and bcl-2 expression, and c-Ki-ras mutations in flat-elevated tubulovillous adenomas and adenocarcinomas of the colorectum: comparison with polypoid lesions.

BACKGROUND: Flat(-elevated) tubulovillous adenomas and adenocarcinomas of the colorectum constitute a specific type of neoplasm with superficial spreading growth. To establish their characteristics, a comparative investigation of a series of tumors was performed. METHODS: A total of 56 flat tubulovillous tumors (39 adenomas, 17 invasive carcinomas) and 154 polypoid tubular or villous tumors (77 adenomas, 77 invasive carcinomas) were comparatively assessed for cell kinetics and molecular alterations. RESULTS: Ki-67 labeling and p53 expression for both types of tumors increased along with degree of dysplasia or invasion, whereas bcl-2 expression showed an inverse decrease. However, apoptotic activity was invariably low in the flat tubulovillous tumors, as compared with the polypoid tumors, in which increase was apparent with tumor progression. The flat tubulovillous tumors also showed a higher frequency of c-Ki-ras mutations (92.9%) than the polypoid tubular tumors (40.0%). CONCLUSIONS: The flat tubulovillous tumor can be considered a distinct entity, with characteristics different from the polypoid counterpart.

Adenocarcinoma↗
PubMed1999

Enhancement of protein kinase activity in the cytosol of regenerating rat liver: regulatory role of endogenous regucalcin.

The effect of regucalcin, a Ca2+-binding protein, on protein kinase activity in the cytosol of regenerating rat liver was investigated. Protein phosphorylation was significantly increased in the liver cytosol obtained at 6, 24, and 48 h after a partial hepatectomy (about 65%) in comparison with that of sham-operated rats. This increase was significantly inhibited by the addition of trifluoperazine (2x10(-5) M), staurosporine (10(-7) M) or genistein (10(-5) M), which is an inhibitor of protein kinases, in the reaction mixture. The presence of regucalcin (0.1-0.5 microM) caused a significant decrease in protein phosphorylation in the cytosol from normal and regenerating rat livers. The effect of regucalcin (0.5 microM) was completely abolished by the addition of anti-regucalcin monoclonal antibody (50 ng/ml). The elevation of protein phosphorylation in regenerating rat liver was significantly enhanced by the presence of anti-regucalcin monoclonal antibody (50 ng/ml). The effect of regucalcin in decreasing protein phosphorylation in the cytosol of regenerating rat liver was not seen in the presence of the antibody. The present study demonstrates that protein kinase activity, is enhanced in the cytosol of regenerating rat liver, and that endogenous regucalcin has an inhibitory role in the enhancement of protein phosphorylation by various protein kinases.

Animals↗
PubMed1999

The Sorin stentless pericardial valve: implant technique and hemodynamic profile.

Stentless porcine xenografts have had significant impact on the hemodynamics, left ventricular remodeling, and survival after aortic valve replacement. We sought to establish a similar trend for the stentless pericardial valve. In a consecutive unselected series of 54 patients over 65 years of age, we refined the implant method for the stentless aortic pericardial valve and defined the pitfalls. We used a detailed echocardiographic study designed by the Food and Drug Administration to define the early valve hemodynamics and changes in left ventricular function. The valve is user friendly. With an easily reproducible implant technique, very low mean (7.1+/-3.4 mm Hg) and peak (13.6+/-6.3 mm Hg) transvalvular gradients were obtained, which did not decline significantly with time. Left ventricular mass index declined accordingly over 6 months (147+/-49 g/m2 to 125+/-39 g/m2). Mild aortic regurgitation, which did not influence left ventricular mass regression, occurred (26%) predominantly in the first half of the series because of size discrepancy between the annulus and a dilated sinotubular junction. Aortic regurgitation was virtually eliminated by tailoring of the sinotubular junction in the noncoronary sinus. The stentless pericardial valve provides excellent early hemodynamics and is a realistic alternative to the stentless porcine xenograft or aortic homograft for subcoronary aortic valve replacement in elderly patients. Valve durability is yet to be defined.

Aged↗
PubMed1999

The Carbomedics "Oxford" Photofix stentless valve (PSV).

The hemodynamic superiority of first-generation stentless xenografts over their stented equivalents is now clearly defined. Issues of durability remain. In light of considerable early experience, we sought to provide an "ideal" stentless valve design with the potential for improved durability by eliminating glutaraldehyde. The Carbomedics Oxford Photofix stentless valve (PSV) is a composite xenograft root constructed from three selected porcine noncoronary cusps fixed by the photofix process. The valve inflow has a low pericardial cuff. Consequently there are no coronaries, cloth, or muscle bar in the structure. The valve was tested in the descending aorta and subcoronary positions of juvenile sheep to compare the influence on calcification of photofixation and the alpha-amino-oleic-acid-treated Freestyle valve. There was a substantial difference between the valves, both in radiographic imaging of calcification and the elemental analysis of calcium and phosphorus. In the valve cusp, calcium content of PSV was 3.98+/-5.77 mg/g versus 14.3+/-19.29 mg/g for the Freestyle valve. Equivalent calcium values for the aortic wall were 1.99+/-3.39 mg/g versus 130.79+/-56.29 mg/g. We consider the composite root configuration without cloth, coronaries, or muscle bar to be a promising valve design. The photofix process minimizes xenograft tissue calcification and appears superior to existing methods.

Animals↗
PubMed1999

[Usefulness of endoscopic polypectomy in early colorectal cancer].

This study was carried out to clarify the usefulness of endoscopic polypectomy in early colorectal cancer. Six hundred and sixty-four patients with polypectomized early colorectal cancer were compared with 89 who underwent surgical resection. Among the polypectomized patients, 361 had pedunculated (Ip)-type, 255 semi-pedunculated (Isp)-type, and 48 sessile (Is)-type cancer. The early colorectal cancer was submucosal-invasive cancer (sm cancer) in 16.1% of Ip, 19.2% of I sp, and 22.9% of Is patients. Among the surgically resected patients, sm cancer was present in 41.2% of Ip. 62.1% of I sp. and 58.1% of Is patient in. The percentage of sm cancer and the tumor size surgically resected patients were greater than in polypectomized patients. Local recurrence and distant metastases were investigated after endoscopic polypectomy during follow-up. Two cases (0.4%) of local recurrence were detected after polypectomy among 555 patients with mucosal cancer. Twenty-three (19.8%) of 116 patients with sm cancer underwent surgical resection after polypectomy due to cancer invasion into the vessels and/or extension to the resected margin recognized in polypectomized specimens. Only one case (0.9%) of local recurrence and no distant metastases were detected after polypectomy in 116 patients with sm cancer. Endoscopic polypectomy is very useful as a minimally invasive surgical technique in the protruding type of early colorectal cancer.

Colonoscopy↗
PubMed1998

Inhibitory effect of calcium-binding protein regucalcin on protein kinase activity in the nuclei of regenerating rat liver.

The effect of Ca2+-binding protein regucalcin on protein kinase activity in the nuclei of normal and regenerating rat livers was investigated. Protein kinase activity in the nuclei isolated from normal rat liver was significantly increased by addition of Ca2+ (500 microM) and calmodulin (10 microg/ml) in the enzyme reaction mixture. Nuclear protein kinase activity was significantly decreased in the presence of EGTA (1.0 mM), trifluoperazine (TFP; 20 microM), dibucaine (10(-4) M), or staurosporine (10(-7) M), indicating that Ca2+-dependent protein kinases are present in the nuclei. Protein kinase activity was significantly elevated in the liver nuclei obtained at 6 to 48 h after a partial hepatectomy. Hepatectomy-increased nuclear protein kinase activity was significantly decreased in the presence of EGTA (1.0 mM), TFP (20 microM), or staurosporine (10(-7) M) in the enzyme reaction mixture. The presence of regucalcin (0.1-0.5 microM) caused a significant decrease in protein kinase activity in the nuclei obtained from normal and regenerating rat livers. Meanwhile, the nuclear protein kinase activity from normal and regenerating livers was significantly elevated in the presence of anti-regucalcin monoclonal antibody (50-200 ng/ml). The present study suggests that regucalcin plays a role in the regulation of protein kinase activity in the nuclei of proliferative liver cells.

Animals↗
PubMed1998

Jarvik 2000 heart: potential for bridge to myocyte recovery.

BACKGROUND: Mechanical bridge to left ventricular recovery is an emerging strategy for the treatment of heart failure. We sought to validate the use of a new intracardiac axial flow impeller pump for this purpose. METHODS AND RESULTS: The Jarvik 2000 Heart was implanted into 30 sheep to ascertain mechanical reliability, biocompatibility, and hemodynamic function. We attempted but failed to anticoagulate with warfarin. Elective explants with survival were performed in 3 animals to simulate bridge to recovery. Extensive autopsy studies were performed in all other animals. At speeds between 8000 and 12 000 rpm the device pumped up to 8 L/min, captured all mitral flow, and augmented cardiac output with elevation of mean arterial pressure. The pump was silent and hemolysis negligible. Nonpulsatile flow did not adversely affect neurological or renal function. Device removal proved straightforward and safe. A fractured inflow bearing occurred in 1 early model. There were no other pump failures, but power interruption occurred when the sheep chewed the cables or head-butted the percutaneous pedestal. At autopsy, there was no thromboembolism or primary thrombus formation in any device. Pump occlusion occurred in 2 sheep with bacterial endocarditis. One electively explanted pump, previously switched off for 5 months, had no thrombus in the device or vascular graft. CONCLUSIONS: The Jarvik 2000 Heart is a major advance in blood-pump technology and increases the scope of mechanical circulatory support. Reliability and ease of removal favor its use for bridge to myocyte recovery, as well as for bridge to transplantation or long-term support.

Animals↗
PubMed1998

Localization of carbohydrate chains of pig sperm ligand in the glycoprotein ZPB of egg zona pellucida.

The three glycoproteins of pig zona pellucida (ZPA, ZPB and ZPC) can be separated into ZPA and a mixture of ZPB/ZPC by gel-filtration HPLC. We have shown previously that the neutral complex-type N-linked carbohydrate chains obtained from ZPB/ZPC possess sperm-binding activity. Intact ZPB and ZPC cannot be separated from each other unless acidic N-acetyllactosamine regions of their carbohydrate chains are removed by endo-beta-galactosidase digestion. The endo-beta-galactosidase-digested ZPB retains the sperm-binding activity. Recently, we have reported that N-linked carbohydrate chains of N-terminal fragment (residues 137-247) obtained from endo-beta-galactosidase-digested ZPB are involved mainly in sperm binding [Yonezawa, N., Mitsui, S., Kudo, K. & Nakano, M. (1997) Eur. J. Biochem. 248, 86-92]. In this study, we separated the intact neutral N-linked chains from the ZPB/ZPC mixture into diantennary chains and triantennary and tetraantennary chains by affinity chromatography on Concanavalia ensiformis agglutinin. An in vitro competition assay revealed that triantennary and tetraantennary chains possess a sperm-binding activity stronger than that of diantennary chains. Three glycopeptides, having one Asn residue to which the carbohydrate chain is linked, were obtained by lysyl endopeptidase digestion of the heat-solubilized zonae containing intact ZPB and lysyl endopeptidase and chymotrypsin A digestion of endo-beta-galactosidase-digested ZPB. From sugar-mapping analysis of the carbohydrate chains from these glycopeptides and comparison with the carbohydrate structures of the main intact neutral N-linked chains of ZPB/ZPC, the triantennary and tetraantennary chains were shown to be localized mainly at Asn220 of ZPB, and diantennary chains were present on all the three potential residues (Asn203, Asn220 and Asn333). These results suggest that the carbohydrate chains linked to Asn220 of ZPB participate predominantly in sperm-egg binding.

Amino Acid Sequence↗
PubMed1998

LVAD power delivery: a percutaneous approach to avoid infection.

BACKGROUND: Driveline infection limits the event-free survival of patients with a left ventricular assist device. With the evolving prospect of improved left ventricular assist devices in the bridge-to-transplantation or recovery setting, we sought to reduce the risk of driveline complications. METHODS: As part of the Oxford Jarvik 2000 research program, we developed a carbon and then titanium pedestal to transmit the electric wires through the skin. In a sheep model, the pedestal was brought out through the skin of the shoulder (n = 10) or the scalp (n = 9) with underlying fixation to the skull. Exit wounds were carefully inspected for healing and infection. Power cable durability tests were performed in 6 additional animals without an implanted pump. RESULTS: The cumulative observation period was 1,491 days (mean time, 78 days; range, 14 days to 198 days). There was no difference in observation period between the two groups. Infection (n = 2) and impaired healing (n = 5) occurred in the mobile tissues at the shoulder. Skull-mounted pedestals were free from infection or healing problems. The electric cables were not interrupted by repeated neck flexion (cumulative observation period, 588 days). The carbon pedestal was replaced by a titanium pedestal when the head butting of the sheep fractured the carbon. CONCLUSIONS: The combination of rigid fixation and highly vascular scalp skin reduces the risk of percutaneous driveline infection and may solve an important outstanding problem in use of left ventricular assist devices.

Animals↗
PubMed1998

Stentless xenograft repair of the dissected aortic root.

We used a Freestyle (Medtronic, Minneapolis, MN) porcine root to replace a regurgitant aortic valve and repair acute type A dissection. A Hemashield (Meadox Medicals, Oakland, NJ) graft was used to replace the ascending aorta with the "open anastomosis" technique. This method is a valuable alternative to conventional root replacement in acute type A dissection.

Aged↗
PubMed1998

Temporary aorto-pulmonary shunt for pulmonary hypertension after truncus arteriosus repair.

We describe successful management of pulmonary hypertension with a reversible aorto-pulmonary (central) shunt and inhaled nitric oxide gas after truncus arteriosus repair. A temporary central shunt may provide a lifeline in those cases refractory to pharmacologic pulmonary vasodilation as long as marginal systemic oxygenation can be maintained.

Administration, Inhalation↗
PubMed1998

Recurrent cardiac myxoma: seeding or multifocal disease?

We describe a patient with left atrial myxoma followed by a second lesion in the left ventricle. Previous reports of "recurrent" myxoma were studied, with the following conclusions: There is little evidence for the process of myxoma seeding, local recurrence can occur through inadequate resection or malignant change, and many alleged recurrences are at a different site and multifocal disease occurs frequently in the familial setting.

Female↗
PubMed1998

Operation for chronic traumatic aortic aneurysm: when and how?

BACKGROUND: There are few guidelines for surgical intervention late after unoperated traumatic aortic rupture. We reviewed our experience and the literature to determine when and how to operate. METHODS: Between 1987 and 1997, we treated 9 patients aged 22 to 82 years with chronic traumatic aneurysm. Seven patients underwent aneurysm resection. Two patients have not been operated on. The injury-to-operation interval ranged from 8 weeks to 18 years (mean, 4.1 years). One patient underwent median sternotomy and patch repair during hypothermic circulatory arrest. Six patients underwent left thoracotomy: 2 were operated on with left atrio-femoral bypass, and 4 with hypothermic circulatory arrest and ascending aortic cannulation. RESULTS: There was no surgical mortality or morbidity. The 2 patients who were not operated on remained asymptomatic without radiologic change in the aneurysm after follow-up of 2 and 9 years. CONCLUSIONS: From this limited experience and literature review, we make the following subjective observations: (1) all patients with new symptoms should be operated on promptly, and (2) asymptomatic densely calcified aneurysms detected more than 2 years after the accident can be observed by repeated tomography unless new symptoms arise.

Adult↗
PubMed1998

Less invasive aortic root replacement.

We performed aortic root replacement using partial upper sternotomy in a patient with Marfan's syndrome. This approach was necessary because of severe pectus excavatum and spinal deformities. Although this method is technically feasible, we would not advocate it for routine use.

Adult↗
PubMed1998

Pelvic leiomyoma in the right atrium.

Intravenous leiomyomatosis is a condition characterized by intravenous growth of histologically benign smooth muscle tumor, originating in the uterus. A case of intravenous leiomyomatosis with right atrial extension in a 64-year-old woman is described. The atrial tumor was successfully removed with a single-stage approach via sternolaparotomy and total circulatory arrest using cardiopulmonary bypass.

Cardiopulmonary Bypass↗