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Biomedical subjects

K Tamura

Publications and source records attributed to K Tamura.

At least 1,081 records · Page 60Linked to original sources
PubMed1989

[Assessment of myocardial oxygen consumption during hypothermic perfusion on arrested heart with perfluorochemical and blood cardioplegia].

Perfluorochemicals (PFC) have been utilized attempting to improve the myocardial protective effect of hypothermic cardioplegia (CP). This study was performed to evaluate the efficacy of PFC against blood in oxygen utilization under hypothermic continuous perfusion of chemically arrested heart and to estimate the maximum oxygen consumption (max MVO2) under unlimited oxygen delivery. Canine hearts isolated hemodynamically were perfused continuously using either PFC-CP or blood-CP. In experiment A (n = 8 in PFC-CP, 7 in blood-CP), perfusion temperature was dropped from 25 to 4 degrees C at a constant perfusion pressure of 40 mmHg at aortic root. MVO2 showed gradual falls as temperature dropped in both groups, and significant difference in MVO2 between two groups was obtained at 10 degrees C (PFC-CP 15.0 +/- 6.5 (SD), blood-CP 9.7 +/- 4.3 microliters/min/g dry wt, p less than 0.05) and 4 degrees C (PFC-CP 11.3 +/- 3.7, blood-CP 7.6 +/- 3.3 microliters/min/g dry wt, p less than 0.05). There was no significant difference in MVO2 between two groups at 25 degrees C (PFC-CP 24.6 +/- 3.5, blood-CP 24.0 +/- 6.6 microliters/min/g dry wt) and 20 degrees C (PFC-CP 19.9 +/- 4.7, blood-CP 18.6 +/- 4.9 microliters/min/g dry wt). In experiment B, the perfusion temperature was kept constant at either 20 degrees C (n = 6 in PFC-CP, 6 in blood-CP) or 4 degrees C (n = 8 in PFC-CP, 7 in blood-CP), and oxygen delivery was increased until the plateau in MVO2 was obtained by increasing the perfusion flow. The asymptote in a hyperbolic relation between oxygen delivery and MVO2 was estimated and considered as max MVO2. At 20 degrees C, max MVO2 was 20.4 microliters/min/g dry wt with PFC-PC and 21.4 microliters/min/g dry wt with blood-CP, without significant difference. At 4 degrees C, max MVO2 was significantly higher (p less than 0.05) in PFC-CP (20.8 microliters/min/g dry wt) than blood-CP (13.9 microliters/min/g dry wt). In conclusion, there seems no significant fall in maxMVO2 below 20 degrees C under unlimited oxygen delivery by PFC-CP and the superiority in oxygen utilization by PFC-CP can be obtained at the myocardial temperature less than 20 degrees C.

Animals↗
PubMed1989

[A case of cardiac metastasis from non-Hodgkin's lymphoma demonstrating interesting findings through radionuclide studies].

We have presented a quite rare case of non-Hodgkin's lymphoma developing cardiac metastasis which was demonstrated and confirmed by radionuclide studies and autopsy. A 57-year-old male with SVC syndrome underwent radionuclide angiography using 99mTc-HSA prior to 67Ga-citrate and 201Tl-chloride studies for suspected right atrial metastasis from non-Hodgkin's lymphoma. The radionuclide angiography revealed a filling defect in the right atrium. 67Ga and 201Tl studies showed increased accumulations of both nuclides in the right atrium, in congruence with the region showing a filling defect through the radionuclide angiography. These results suggest that combined radionuclide studies, such as radionuclide angiography, 67Ga and 201Tl studies, might be useful in detecting metastatic tumor in the heart.

Citrates↗
PubMed1989

[Xenon-enhanced CT CBF measurements in intracranial vascular malformations].

In the management of intracranial vascular malformations, it is important to know the regional cerebral blood flow in its surrounding structure. However, CT scan with contrast medium and angiography have only a limited ability to estimate the rCBF. In this study, stable xenon-computerized tomography scanning by means of the end-tidal gas-sampling method was performed in eleven patients with intracranial vascular malformations. Seven of the patients had arteriovenous malformations, three had venous angiomas and one had aneurysm of the vein of Galen. In two patients with large arteriovenous malformations, in two with "larger" venous angioma and in one with aneurysm of the vein of Galen, rCBF values were significantly reduced, particularly adjacent to the malformations. In contrast, there were no areas showing reduced rCBF in cases where the malformations were small. This indicates development of ischemia correlates with the size of malformations. From the xenon-enhanced CT scan and angiographic findings, the presence of steal phenomenon with venous congestion might be a cause of rCBF reduction in those cases where ischemia exists.

Adolescent↗
PubMed1989

[Operative results in cancer of the pancreas, especially complicated with large vascular involvement].

Surgical treatment has been performed in 25 cases of cancer of the pancreas. Localized large vascular involvements of portal vein, celiac axis, common hepatic artery and/or superior mesenteric artery by the pancreatic cancer were observed in 11 cases, which necessitated total or subtotal pancreatectomy associated with segmental resection of the vessels with vascular reconstruction in 7 cases but in remaining 4 cases resectional procedure was not performed. Curative pancreaticoduodenectomy was carried out in 5 cases without large vascular involvement and non-curative pancreatectomy in one case. Exploratory laparotomy or only anastomosis for the bile duct or the intestine was done in 8 cases. The operative resectability rate was 52% and the curative one was 44%. The regional pancreatectomy seemed to contribute to improvement of resectability. However, one year survival rate was only 42% (2 year, 0%) in the curatively resected cases with large vascular involvement, while 5 year survival rate was 67% in those without vascular involvement. The quality of life after extended total pancreatectomy was distressful. On the other hand, two extended totally pancreatectomized cases with successful autotransplantation of distal pancreas are living at one year and 3 months after operation respectively, and enjoying the common social life at present.

Aged↗
PubMed1989

[Establishment and biological characterization of human medulloblastoma cell lines].

Two cell lines of human medulloblastoma (ONS-76 and ONS-81) were established, and their biological characteristics were investigated. The cell line, ONS-76, was established from a tumor specimens obtained from a large cerebellar tumor of a 2-year-old girl. The pathological diagnosis was a typical medulloblastoma. The other cell line, ONS-81, was derived from a metastatic tumor in right frontal lobe of a 9-year-old girl. The tumor specimens were minced into fragments approximately 1 mm in diameter and cultured in plastic culture flasks in RPMI 1640 medium supplemented with 10% heat-inactivated fetal calf serum (FCS) and 50% patients serum. The cells growing as a monolayer were subcultured in RPMI 1640 supplemented with 10% FCS and initially with L-glutamine, sodium pyruvate, and nonessential amino acid. Microscopically, both cultured cells exhibited various morphological appearances, and this morphological heterogeneity seemed to be specific for medulloblastoma cells. The in vitro population doubling time of ONS-76 and ONS-81 were 18.6 and 19.2 hr, respectively. The ONS-76 and ONS-81 cells formed subcutaneous tumors in nude mice as serial transplantable xenograft, and these tumors had a microscopic appearance similar to that of the original medulloblastoma. Ultrastructurally++, the cultured cells showed primitive, undifferentiated appearance, and no neuronal or glial structures were not seen. Immunohistochemical studies showed that both cells expressed neuron-specific enolase (NSE) and neurofilament protein (NFP 200 K, 145 K), but glial fibrillary acidic protein (GFAP) and S-100 protein were not detected. The NFP immunoreactivities of both cultured cells were demonstrated as abnormal perinuclear deposits.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Glycoprotein Ib has a partial role in platelet-von Willebrand factor collagen interaction.

The adhesion of human fixed washed platelets (FWP) to collagen was decreased after treatment with Serratia marcescens protease (SP), which removed 95% of the glycocalicin from platelet membrane glycoprotein (GP) Ib. However, the diminished adhesion of SP treated FWP to collagen could still be increased in the presence of purified von Willebrand factor (vWF). This ability to vWF to increase FWP adhesion to collagen is defined as collagen cofactor (CCo). The adhesion of FWP to collagen was not affected by a monoclonal antibody (MAb) to GP IIb/IIIa (10E5), that inhibits ADP and collagen induced platelet aggregation. On the other hand, it was decreased by 50% by a MAb to GP Ib (6D1), that inhibits ristocetin induced platelet aggregation. Adhesion of FWP in buffer to collagen was completely inhibited by Ricinus communis agglutinin I or concanavalin A, while Lens culinalis agglutinin and wheat germ agglutinin showed 50% inhibition. The FWP adhesion to collagen in the presence of vWF (normal plasma) was unaffected by MAbs to GP IIb/IIIa (10E5, P2, HPL1) but was decreased to 32-38% by MAbs to GP Ib (6D1, AN51, HPL11). A MAb to vWF (CLB-RAg 35), that inhibits ristocetin induced binding of vWF to platelets, decreased the CCo of normal plasma by 70%. The MAb, CLB-RAg 201, that inhibits the binding of vWF to collagen, completely inhibited the CCo of normal plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1988

Transplant-induced recovery from 6-OHDA lesions of the nigrostriatal dopamineneurones in mice.

Attempts to reconstruct the damaged nigrostriatal pathway in experimental models of Parkinson's disease have thus far been carried out in animals with neurotoxically induced dopamine deficiency. Our study established that unilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal dopamine (DA) neurons produced a well-characterized functional asymmetry in the behaviour of the C57BL/6 (H-2b) mice. The intraperitoneal administration of methamphetamine induced ipsilateral rotation at 7-20 turns/min 1 x 10(6) syngenic DA-rich cells of embryonic ventral mesencephalon were stereotaxically transplanted in the caudate-putamen. A complete recovery of methamphetamine-induced rotational response was produced around the 60th day after the syngenic cell suspension graft. And a complete compensation of the rotational response was also brought about with the DA-rich cells from embryonic ventral mesencephalon (crown-rump length; 10-13 mm) of allogenic C3H/HeN (H-2k) mice. The FACS IV analysis revealed no H-2 (Kk and Iak) antigens before transplantation of these embryonic cells. Immunohistochemistry showed that the dopaminergic fibers had grown predominantly into the ipsilateral caudate-putamen. These results provide evidence of integration of syngenic and allogenic grafts and host tissue. And the immunological response in the transplanted brain are under investigation.

Animals↗
PubMed1988

Effects of phenytoin on cell-mediated immunity.

The effects of phenytoin on cellular immunity were examined in murine models. Fresh splenocytes were obtained from mice which had received 1 mg/day of phenytoin i.p. for 28 days. The serum concentration of phenytoin in these animals was 10-20 micrograms/ml. The proliferative response of splenocytes to mitogens was assessed by 3H-thymidine incorporation. The cytotoxic activities of cells such as natural killer (NK) cells, cytotoxic T lymphocytes (CTL), and lymphokine-activated killer (LAK) cells were estimated by a 4-h 51Cr release assay. The 3H-thymidine incorporation of splenocytes was reduced significantly (P less than 0.01) in phenytoin-treated mice. The NK and CTL activities of splenocytes from phenytoin-treated mice were significantly suppressed. However, the LAK activity of phenytoin-treated mice was equal to that of control mice.

Animals↗
PubMed1988

An adoptive immunotherapy of patients with medulloblastoma by lymphokine-activated killer cells (LAK).

An adoptive immunotherapy of 6 patients with medulloblastoma by lymphokine-activated killer (LAK) cells is described. They were from 2 to 9 years in age and had cerebrospinal fluid (CSF) dissemination of the tumours. All patients underwent the whole-neuraxis irradiation and chemotherapy. After the usual treatments, they were submitted to an adoptive transfer of one-haplotype identical LAK cells. The LAK cells were induced from peripheral blood lymphocytes (PBL) of their relatives with human recombinant interleukin-2 (rIL-2). 3 - 15 x 10(9) LAK cells were transferred intrathecally in 2-3 months. In 3 of 6 patients, neurological signs were improved and malignant cells had never been detected on CSF cytology after the adoptive immunotherapy. One among these 3 patients showed complete response in 20 months. Thus, this is an attractive approach for the treatment of medulloblastoma with CSF dissemination of the tumour which current therapeutic intervention can not cure.

Cerebellar Neoplasms↗
PubMed1988

Studies of fluorescence depolarization at high pressures of dimyristoylphosphatidylcholine liposomes containing poly(gamma-benzyl-L-glutamate).

The behaviors of four kinds of poly(gamma-benzyl-L-glutamate) (PBLG) molecules and their locations in dimyristoyl-phophatidylcholine (DMPC) liposomes were studied by fluorescence techniques at high pressures of up to 981 bar. The fluorescent substances 1,6-diphenyl-1,3,5-hexatriene (DPH), 1-aminonaphthalene-8-sulfonate (ANS) and PBLGs labeled with a dansyl group were used as probes of hydrophobic and hydrophilic spheres and the motions of polypeptides, respectively. The changes in mobilities of the PBLG molecules depended on their concentrations, degrees of polymerization and the lengths of hydrocarbon chains attached to their terminals. The molecular motions of the PBLGs were altered by increase in their contents, caused by squeezing the PBLG molecules out of the membranes. Models of the membranes and the behavior of polypeptides in the membranes at high pressures are discussed.

Dimyristoylphosphatidylcholine↗