Search PubMed⌕ Search

Biomedical subjects

T Yamamura

Publications and source records attributed to T Yamamura.

At least 379 records · Page 21Linked to original sources
PubMed1985

Rate of cholesteryl ester transfer between high and low density lipoproteins in human serum and a case with decreased transfer rate in association with hyperalphalipoproteinemia.

The rate of cholesteryl ester transfer between intrinsic high and low density lipoproteins (HDL and LDL) was measured in human serum in the absence of lecithin:cholesterol acyltransferase (LCAT) and very low density lipoproteins. The rate was calculated according to the equilibrium transfer model between the two lipoprotein cholesteryl ester pools. The average rate of the transfer was 213 +/- 95 nmol/h/ml (mean +/- S.E.) for all 20 normal and 13 hyperlipoproteinemic subjects. The transfer rate in individual serum was higher by several times than the cholesterol esterification rate, showing that cholesteryl ester generated by LCAT on HDL is promptly distributed among various lipoprotein subclasses. The rate of cholesteryl ester transfer in the serum was significantly proportional to the product of intrinsic HDL and LDL concentrations, a possible indicator of the frequency of collision between these lipoproteins, for the range of physiological lipoprotein concentrations. Among the subjects analyzed was a patient with remarkable hyperalphalipoproteinemia accompanied by hypertriglyceridemia, who showed a very low rate of cholesteryl ester transfer in relation to his LDL and HDL concentrations. Compositional analysis of lipoprotein lipids of the patients also supported the possibility of impaired neutral lipids transfer activity among lipoproteins in the blood.

Adult↗
PubMed1985

Accurate localization of insulinoma using percutaneous transhepatic portal venous sampling--usefulness of simultaneous measurement of plasma insulin and glucagon levels.

By means of percutaneous transhepatic portal venous sampling (PTVS), plasma insulin and glucagon levels were determined simultaneously at various sites of the hepatic portal venous system in two patients with insulinoma and four patients without. In the two cases of insulinoma, an obvious rise of insulin concentration was observed at the vicinity of the tumour, while glucagon levels were not elevated in the blood samples showing an insulin peak. In the remaining four cases without evidence of insulinoma, significant step-ups of plasma insulin occurred in the splenic vein as well, but were accompanied with concomitant elevation of plasma glucagon levels in the same blood samples. Thus, by measuring insulin alone, false positive data may frequently be obtained when PTVS is performed on patients with suspected insulinomas. The simultaneous measurement of insulin and glucagon might be helpful in avoiding such errors.

Adenoma, Islet Cell↗
PubMed1985

Effect of truncal vagotomy on GIP release induced by intraduodenal glucose or fat in dogs.

In order to elucidate the role of the vagus nerve in the release of gastric inhibitory polypeptide (GIP), mongrel dogs were given a 4-min intraduodenal infusion of 10 g glucose or 5 g soybean oil before and again 1 month after truncal vagotomy (TV). The basal GIP concentrations were significantly elevated after TV. The plasma GIP levels following glucose infusion in the vagotomized dogs were significantly higher than those in the untreated dogs, whereas the GIP levels following fat infusion were not affected by TV. These results suggest that TV influences glucose-induced GIP release but not fat-induced GIP release, indicating that different mechanisms of the vagus nerve may be involved in glucose- and fat-induced GIP secretions.

Animals↗
PubMed1985

Differentiation of pulpal cells and inductive influences of various matrices with reference to pulpal wound healing.

Based on recent literature, the dynamics of mesenchymal cells in transplantation of various tissues and matrices, as well as the origin of new odontoblasts which participate in the formation of the dentin bridge, are described. Experiments involving implantation of pulp, periosteum, perichondrium, treated dentin, and bone matrices were performed to emphasize the capability of these cells to produce hard tissue. Light and electron microscopic and autoradiographic studies were carried out to clarify the origin of replacement odontoblasts. It appears that the pulp cells, endothelial cells, and pericytes become undifferentiated mesenchymal cells following pulp exposure. These mesenchymal cells differentiate into odontoblasts, which subsequently produce a dentin matrix. Pulp tissues autografted to non-pulpal sites, elaborated bone (or osteodentin) matrix, but they did not graft to tubular dentin. An experiment on dentin bridge formation, using germ-free rats, demonstrated that the pulp tissue has intrinsic healing potential. Therefore, it was concluded that the ability of pulp tissue to elaborate hard tissues depends on its environment.

Animals↗
PubMed1985

Cutaneous malignant lymphomas. A clinicopathologic study of thirty-seven cases.

Clinical and histological findings in 37 cases of cutaneous lymphomas other than mycosis fungoides and Sezary syndrome were investigated; there were 31 in adults and 6 in children. Cutaneous lesions were the first manifestations of the diseases in all cases, and they appeared mostly as tumors or nodules. Cytomorphologically, about a half of the cases showed proliferations of large cleaved, non-cleaved cells or immunoblasts (Group I). Eight cases showed a polymorphous appearance containing convoluted cells of various size (Group II). Five cases in children demonstrated monomorphous proliferation of uniform-sized lymphoblasts (Group III). The cytologic findings in 6 cases did not fit into any lymphoid groups (Group IV). The clinical findings observed in each group were reviewed and compared. Follow-up study revealed that the prognosis of Group I was the poorest among the four groups.

Adolescent↗
PubMed1985

[Gut hormone profiles after various types of gastrointestinal surgery].

Gastrointestinal and pancreatic hormone responses to test meal or oral glucose were studied in totally gastrectomized patients (TG), subtotally gastrectomized patients with BI and BII, patients with pylorus preserving gastrectomy (PPG), a case of massive (4m 15 cm) bowel resection (MBR) and patients with pancreatoduodenectomy (PD), and compared to the pattern of healthy control subjects (HC). Plasma IRI, GIP and GLI responses to meal in TG and BII were significantly higher, and those in BI appeared to be higher than those in HC. In contrast, those hormonal patterns in PPG were similar to HC. Thus, it seemed that PPG was more physiological than any other gastrectomies in the viewpoints of GI hormonal patterns. In a case of MBR, plasma GLI response to oral glucose, expressed as peak/basal GLI, was significantly higher compared to HC. This higher GLI responsiveness together with remarkably high plasma gastrin level in this case might have a role in stimulating the adaptative changes found after MBR. IRI and GIP responses to oral glucose were impaired following PD without pancreatojejunostomy, while after operating pancreatojejunostomy, those responses restored in part which might suggest the significant role of the pancreatic juice into the jejunum in releasing mechanism of these hormones.

Aged↗
PubMed1984

Copper complexes at N- and C-site of ovotransferrin: quantitative determination and visible absorption spectrum of each complex.

Copper complexes at the two sites of ovotransferrin (TF) differed markedly in the rate of Cu release by EDTA. During the reaction, lambda max of the remaining Cu-Tf complex shifted to red side, while the difference spectrum of FenCu2-nTf vs. FenTf in which the N-site had been preferentially occupied with Fe had lambda max at blue side from that of Cu2Tf, 440 nm. From these results, the intrinsic spectrum for Cu-complex at each site was assigned: lambda max 450 nm for N- and 430 nm for C-site. The differences in the release rate and the spectrum can be used for the identification of the two domains of Tf and for the analysis of metal-binding behavior of each site.

Animals↗
PubMed1984

Changes occurring in plasma membranes and intercellular junctions during the process of carcinogenesis and in squamous cell carcinoma.

A 0.5% mineral-oil solution of 9.10-dimethyl-1.2-benzanthracene (DMBA) was applied to artificial cecal pouches in the lower lips of rats. Ultrastructural studies were made of plasma membranes and intercellular junctions during the process of malignant transformation in the oral mucosal epithelium and after squamous cell carcinoma had been induced by the carcinogen. After the administration of DMBA, the inner leaflet of the membranes where the microfilaments are attached showed high electron density and intramembranous particles on the P-face of basal cells decreased to about half that of controls. However, on the E-face the number of intramembranous particles increased by approximately 10% compared with controls. Though the normal size range for intramembranous particles was 9-12 nm, the administration of DMBA caused aggregations of from three to six particles on the P-face. In squamous cell carcinomas, only the outer leaflet of the membranes showed high electron density; the number of intramembranous particles was 30% higher on the P-face and approximately three times higher on the E-face compared with controls and the morphology of the intramembranous particles, which formed irregular aggregates of from five to 20 particles, was specific. In animals treated with DMBA, the number of gap junctions decreased by between 50% and 70%, although no structural changes occurred. In squamous cell carcinomas, the area of gap junctions was about 50% lower and the number of gap junctions about 40% lower than in controls. Changes in the number and area of desmosomes were similar to those of gap junctions both in the DMBA-treated animals and in squamous cell carcinomas.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Intercellular junctions in odontoblasts of the rat incisor studied with freeze-fracture.

The morphology and distribution of various types of intercellular junctions were investigated in young odontoblasts. Gap junctions were found between odontoblasts as well as between odontoblasts and fibroblasts in the dental pulp. The junctions between odontoblasts were larger and more numerous than those between odontoblast and fibroblast, suggesting that the former may play an important role in regulating cellular activity and the latter may provide a pathway of low electrical resistance between odontoblast and nerve fibres. Irregularly-shaped gap junctions appeared as small aggregations of particles associated with a particle-free area and may indicate that the junction might not yet have been completely assembled. Tight junctions were observed at the distal ends of the young odontoblasts, arranged to form small maculae or faciae occludentes rather than belt-like zonulae. It is therefore not likely that the junction contributes to barrier function in the young odontoblasts. Although structures resembling typical desmosome were recognizable, this type of junction in odontoblasts is properly termed a desmosome-like junction from its morphological peculiarities.

Animals↗
PubMed1984

A new isoform of apolipoprotein E--apo E-5--associated with hyperlipidemia and atherosclerosis.

Heterogeneity of apolipoprotein E (apo E) was analyzed by isoelectric focusing of apo VLDL in patients with hyperlipidemia and/or atherosclerosis. Six major apo E phenotypes were shown, in agreement with the current genetic model which is composed of 3 major apo E isoproteins, apo E-4, apo E-3 and apo E-2, resulting from three apo E alleles, epsilon 4, epsilon 3 and epsilon 2, at a single genetic locus. We recognized an additional apolipoprotein band, which is located basic to apo E-4 on an isoelectric focusing gel, in 3 patients with hyperlipidemia. The new apolipoprotein component, named apo E-5, was identical with ordinary apo E in apparent molecular weight by SDS-polyacrylamide gel electrophoresis and in its interactions with heparin-Sepharose gel and with anti-apo E antibody. This mutant apo E isoprotein had an isoelectric point more basic by one unit of charge than apo E-4. Two of 3 patients had the phenotype E5/3, and the other the phenotype E5/4. Genetic analysis of the apo E phenotypes in family members of the patients indicated the presence of a new apo E allele (epsilon 5) at the same genetic locus as hitherto known alleles. Since most of the subjects above 50 years old with apo E-5 had ischemic heart disease or cerebral infarction, it was suggested that the mutant apo E-5 may possibly be related to the development of atherosclerosis.

Apolipoproteins↗
PubMed1984

Acinic cell carcinoma arising in the glossopalatine glands: a report of two cases with electron microscopic observations.

Two cases of acinic cell carcinoma arising in the glossopalatine glands were examined with the electron microscope by means of conventional thin sectioning and freeze-fracturing. Light and electron microscopic observation revealed that the tumors consisted of three types of cells: serous-type, ductlike, and vacuolated cells. Serous-type cells had numerous secretory granules, some of which were discharged into the intercellular spaces. Ductlike cells were smaller, usually lacked secretory granules, and were similar to intercalated duct cells. Vacuolated cells had electron-opaque vacuoles in the cytoplasm. Our findings supported the hypothesis that acinic cell carcinoma may represent a neoplasm of multipotential duct cells which have differentiated mainly into granulated serous cells. Freeze-fracture images of this tumor revealed that tight junctions were composed of ten or more interlinked strands with elongation of basal frontier strands. These findings suggested that the junctional morphology of the tumor resembled that of developing salivary glands and was associated with the degree of cellular differentiation.

Carcinoma↗
PubMed1984

The cutaneous lymphomas with convoluted nucleus. Analysis of thirty-nine cases.

The clinical and histopathologic findings in thirty-nine cases of cutaneous lymphoma characterized by a proliferation of convoluted cells were reviewed. Thirty patients (77%) presented with erythematous or papular lesions (group I). The remaining nine patients (23%) presented with cutaneous nodules or tumors without erythematous lesions (group III). Histologically, the polymorphous infiltration was the common feature in both groups, but the presence of epidermotropism in group I was contrasted to the absence of epidermotropism in group II disease. The patients in group I had a higher median age (54 years) than those in group II (35 years), and a more favorable 3-year survival rate (44%) than that of the latter (19%). An evolution occasionally occurred from the epidermotropic to the nonepidermotropic form, followed by a poor clinical course. When the skin lesions were nonepidermotropic , irrespective of preceding clinical course, the prognosis was poor.

Adult↗