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Biomedical subjects

K Sawada

Publications and source records attributed to K Sawada.

At least 307 records · Page 17Linked to original sources
PubMed1989

[A case of aortitis syndrome with left coronary ostial stenosis treated by aorto-coronary bypass grafting].

A 22 years-old woman who was suffered from effort angina caused by aortitis syndrome was hospitalized. The coronary arteriogram showed the left main trunk stenosis more than 99% with the visualization of the left anterior descending and left circumflex through the co-lateral vessels from right coronary artery. After successful sequential aorto-coronary bypass grafting to left anterior descending artery, the patient has been free from anginal pain.

Adult↗
PubMed1988

Quantitation of specific binding of erythropoietin to human erythroid colony-forming cells.

Highly purified human erythroid colony-forming cells (ECFC), which consist predominately of colony-forming units-erythroid (CFU-E), were prepared from human blood and used to study the binding and processing of erythropoietin (Ep). When radioiodinated human recombinant Ep (125I-rEp) was incubated with these cells, binding was specific and saturable. Specific binding was directly proportional to cell concentration and did not occur with other human cells. Saturation of specific binding at 3 degrees C occurred at 1 nM (3.9/U/ml), and Scatchard analysis revealed two classes of binding sites on the cell surface. Of a total of 1,050 binding sites per ECFC, one-fifth had a Kd of 0.10 nM, while the remainder had a Kd of 0.57 nM. Specific binding was twofold greater at 37 degrees C than at 3 degrees C, and removal of surface-bound Ep with acid indicated that 125I-rEp was internalized into the cells after incubation at 37 degrees C. Further incubation at this temperature showed a decline of cellular radioactivity, with a release of small molecular weight degradation fragments into the medium. These studies demonstrate two classes of receptors for Ep on normal human ECFC. Internalization and degradation of EP occur, and the biologic effect of the hormone is produced by a small number of Ep molecules, as demonstrated in murine erythroid progenitor cells.

Adult↗
PubMed1988

Age-related changes in rat hepatic and renal thyroid hormone-sensitive enzymes--different responses to acute and chronic L-triiodothyronine stimulation.

Using young (5-6 weeks) and adult (12-14 months) male Sprague-Dawley rats, the responses of hepatic and renal cytosolic malic enzymes (ME) and mitochondrial alpha-glycerophosphate dehydrogenase (alpha-GPDH), have been assessed following acute and chronic L-triiodothyronine (T3) administration. In control (untreated) animals a significant reduction of renal ME as well as hepatic and renal alpha-GPDH activity with increased age were observed but renal ME activity was not age-related. Following acute T3 stimulation (200 micrograms T3/100 g body wt single injection), the levels of hepatic ME and alpha-GPDH as well as renal alpha-GPDH but not renal ME remained lower in the adult than in the younger group. After chronic T3 stimulation (15 micrograms T3/100 g body wt for 7 days) or 200 micrograms T3/100 g body wt for 4 days), the enzyme levels remained significantly lower in older animals for hepatic ME but were no longer different for hepatic and renal alpha-GPDH, while renal ME, which was not altered with age, had values that were the same as in the younger group. These studies have demonstrated that age-related changes in hepatic and renal T3-sensitive enzymes could not be attributed solely to T3 occupancy of nuclear receptor binding sites, but may be influenced by other factors depending upon the specific tissues and subcellular T3-sensitive enzymes being assessed.

Age Factors↗
PubMed1988

Activation of detergent-solubilized rat hepatic 5'-iodothyronine deiodinase by NADPH and nonglutathione cytosolic components.

An investigation was made of the possible role of the hepatic microsomal membrane in the activation of 5'-iodothyronine deiodinase (5'-DI) by a cytosolic activating system consisting of fraction A (relative mass (Mr) greater than 60,000), fraction B (Mr, approximately 13,000), and NADPH. Activation of 5'-DI in washed microsomes was compared with that of a microsome extract prepared by solubilization with 3-[(3-cholamidopropyl)dimethylammonio]-1-propane sulphonate and further purification by fractional precipitation with polyethylene glycol and by DEAE-Sephacel chromatography. All 5'-DI preparations exhibited qualitatively similar dependence upon NADPH and cytosolic factors in fractions A and B for 5'-DI activation and were relatively unresponsive to NADH. Activation of solubilized preparations, unlike that of intact microsomes, was more readily inhibited by low concentrations of detergent and not inhibited by NADPH concentrations above 0.25 mM. Attempted purification of 5'-DI failed to produce a substantial increase in specific activity of the enzyme. It is concluded that, while glutathione-independent cytosolic factors and NADPH can activate 5'-DI in the absence of an intact microsomal membrane, some membrane constituents removed during solubilization and purification of the enzyme are required for maximal activation.

Animals↗
PubMed1987

Enhanced expression of a glyceraldehyde-3-phosphate dehydrogenase gene in human lung cancers.

We have shown that a Mr 37,000 protein whose expression is strongly enhanced in human lung cancer tissues is the subunit of glyceraldehyde-3-phosphate (GAPDH, EC 1.2.1.12). We have isolated a GAPDH complementary DNA from human lung cancer cells and deduced the complete amino acid sequence of the encoded protein. The structure of the lung cancer GAPDH is identical to that of liver GAPDH. In addition, we have found that GAPDH mRNA expression is markedly increased in human lung cancer tissues. These results disclose a molecular basis of increased glycolysis in cancer cells and reveal an important role of energy creating reaction in cancer cell growth.

DNA↗
PubMed1987

Development of cell systems to study viral gene transcription at the initial phase of Epstein-Barr virus infection.

Two infection systems have been introduced in order to study viral gene expression at the initial period of Epstein-Barr virus (EBV) infection which leads to immortalization. The data indicate that major viral gene expression in tonsil lymphocytes at 2 days post-infection (p.i.) with EBV is very similar to that observed in latently infected cells. Both tonsil lymphocyte and BJAB cell (lymphoblastoid cells free of EBV genome) infection with EBV induced similar viral gene transcription. Twelve cDNA clones were prepared from poly(A) RNA of tonsil lymphocytes infected with EBV 2 days p.i. by hybridization with BamHI fragments of EBV DNA. Some cDNAs were derived from primary transcripts of the BamHI-WYHK region, suggestive of splicing of a large transcript. It is possible that a number of cDNA clones may be derived from cellular genes. The derivation of these cDNA clones is being studied.

Bacteriophage lambda↗
PubMed1987

Identification of the specific proteins associated with differentiation of spermatogonia in mice by two-dimensional gel electrophoresis.

Protein synthesis in testicular germ cells was studied during the differentiation of Type A spermatogonia in testes from adult cryptorchid mice to Intermediate and Type B spermatogonia in organ culture by two-dimensional gel electrophoresis. By comparing the patterns of Type A spermatogonia with those of differentiated (Intermediate and Type B) spermatogonia, we found two newly synthesized protein spots that correlated with differentiation. The isoelectric points (pIs) and molecular weights (MWs) of these proteins were estimated to be approximately pI 5.4, MW 67,000, and pI 5.8, MW 28,000, respectively.

Animals↗
PubMed1987

Purification of human erythroid colony-forming units and demonstration of specific binding of erythropoietin.

Morphological and biochemical studies of human colony-forming units-erythroid (CFU-E) have been hindered by their extreme rarity. Since burst-forming units-erythroid (BFU-E) develop into CFU-E, we used normal human blood BFU-E to generate large numbers of highly purified CFU-E in vitro. Using density centrifugation, sheep erythrocyte rosetting, surface immunoglobulin-positive cell depletion, adherence to plastic, and negative panning with monoclonal antibodies, human blood BFU-E were purified from 0.017 to 0.368%, a 22-fold purification with a 43% yield. The panned cells were cultured in methylcellulose with recombinant erythropoietin (rEp) and conditioned medium for 9 d. These cells were then collected and CFU-E were further purified using adherence and density centrifugation. This yielded almost 10(7) erythroid colony forming cells with a purity of 70 +/- 18%. Analysis of these cells by light and electron microscopy showed 94% erythroid cells. The prominent cell was a primitive blast with high nuclear/cytoplasmic ratio, dispersed nuclear chromatin and a distinct large nucleolus. The relation between the number of erythroid colonies and the number of day 9 cells plated in plasma clots was a straight line through the origin with a maximum number of erythroid colonies at 1 U/ml of rEp and no erythroid colonies without rEp. Specific binding with 125I-rEp showed that 60% of the binding was inhibited by excess pure erythropoietin (Ep), but not by albumin, fetal calf serum, and a variety of growth factors or glycoproteins. By days 12-13 of cell culture, when the progenitor cells matured to late erythroblasts, specific binding markedly declined. In this study, human CFU-E have been isolated in sufficient purity to characterize the morphology of these rare cells and in sufficient numbers to measure specific binding of Ep.

Antibodies, Monoclonal↗
PubMed1987

Voltage- and rate-dependent depression of Vmax of action potentials by a new antiarrhythmic agent, E-0747, in swine cardiac Purkinje fibers.

Effects of a new antiarrhythmic agent, E-0747, on action potentials of swine cardiac Purkinje fibers were studied using standard microelectrode techniques. E-0747 decreased the maximum rate of rise (Vmax) of action potentials at concentrations higher than 3 X 10(-7) M at a frequency of 1 Hz without change in resting membrane potential. E-0747 (3 X 10(-6) M) shifted the steady-state relationship between the Vmax and the resting membrane potential in a hyperpolarizing direction by 9.2 +/- 0.9 mV. E-0747 depressed the Vmax in a rate-dependent manner. At a concentration of 3 X 10(-6) M, the depression was approximately 50% at a stimulation of 3.3 Hz. E-0747 (3 X 10(-6) M) did not depress the Vmax of the first action potential after a rest period of approximately 30 min, but subsequently reduced the Vmax with successive stimulations reaching a new steady level after approximately 20 min. The time course of recovery from inactivation of the Vmax in the presence of E-0747 (10(-6) M) did not differ from that of the control. E-0747 shortened the action potential duration (APD), but did not affect the ratio of effective refractory period (ERP) to APD. These results suggest that E-0747 depresses the Vmax by closely associating with open and/or inactivated sodium channels. It may be classified as an antiarrhythmic agent of class 1C type of the Vaughan Williams' classification.

Action Potentials↗
PubMed1987

Promoting effect of 5 beta-chol-3-en-24-oic acid on N-methyl-N-nitrosourea-induced colonic tumorigenesis in rats.

The effect of 5 beta-chol-3-en-24-oic acid (delta 3) on N-methyl-N-nitrosourea (MNU)-induced colonic tumorigenesis was studied by intrarectal injection of these compounds in rats. Female Fischer rats received 0.5 ml of distilled water (DW) alone or DW containing 2.5 mg of MNU twice in one week followed by 0.5 ml of peanut oil (PO) alone or PO containing 1 mg of delta 3, or 1 mg of lithocholic acid (LC) thrice weekly for 48 weeks. Thus, 6 groups were employed as follows: group I, DW + PO (n = 12); group II, DW + delta 3 (n = 30); group III, DW + LC (n = 30); group IV, MNU + PO (n = 30); group V, MNU + delta 3 (n = 30) and group VI, MNU + LC (n = 37). Fecal bile acid profiles were analyzed before and during the treatment. Numbers of rats bearing colonic tumor were none in the groups without MNU, but 5 (17%) in group IV, 15 (50%) in group V and 12 (32%) in group VI (corrected X2 = 6.07, P less than 0.025 for group IV vs V, and 1.42, P less than 0.3 for group IV vs VI). Total numbers of tumors were 7, 17 and 15 in group IV, V and VI, respectively, and they were mostly adenomas and adenocarcinomas. A breast fibroadenoma in one rat of group VI was the sole extracolonic neoplasm in these rats. Total fecal bile acids ranged from 7.7 to 10.5 mumol/g dry feces during the study without any significant quantitative or qualitative difference with respect to with or without bile acids and MNU treatment. These results indicated that delta 3 promoted MNU-induced colonic tumorigenesis in rats without alteration in bile acid metabolism.

Animals↗
PubMed1987

[A trial of sustained-release anticancer chemotherapy with silicone].

Mitomycin C (MMC) was incorporated into liquid silicone which was then vulcanized into solid form. Pellets of MMC were implanted at 5 different sites within the mediastinum of 9 dogs. Implants were removed at regular intervals after sacrificing the test animals. Though the mean doses of MMC released leveled off during 4 weeks, it began to increased rapidly after the 5 week with the result of, this one month delay compared with in vitro. Necrosis appeared to prevent MMC from liberating itself from the implants. Further, the cumulative doses of MMC released were found to be superior in the subaortic and subcarinal sites than in the other three places. No serious complications were encountered in this study.

Animals↗
PubMed1986

Intermediate Mr cytosolic components potentiate hepatic 5'-deiodinase activation by thiols.

The role in the activation of microsomal 5'-deiodinase (5'-DI) of rat hepatic cytosolic components of Mr approx. 13,000 (Fraction B) was studied in the presence of various concentrations of thiol compounds such as dithiothreitol (DTT), dihydrolipoamide (DHLA), GSH, and 2-mercaptoethanol (2-ME). Although Fraction B (which was prepared by gel filtration to exclude GSH and GSSG) had no intrinsic 5'-DI activity, could not stimulate microsomal 5'-DI activity in the absence of added thiol and did not contain GSH as a mixed disulphide, it could produce a 3-fold increase in the maximal deiodinase activity achievable with DTT as well as other thiols, with the order being the same as the activation potency of these thiols in the absence of Fraction B (i.e. DHLA greater than DTT greater than 2-ME greater than GSH). These observations suggest that: a component of cytosolic Fraction B, designated 'deiodination factor B' (DFB), operates as an efficient intermediary to enhance activation of microsomal 5'-DI by thiols through a mechanism independent of GSH; thiols may participate in a non-specific thiol-disulphide exchange with inactive (oxidized) DFB to convert it into an active form that contains one or more thiol groups and is more effective than GSH or other thiols in facilitating the re-activation of inactive (oxidized) microsomal 5'-DI thiol (ESI) to its active state (ESH).

Animals↗
PubMed1986

Properties of cytosolic components activating rat hepatic 5' [corrected]-deiodination in the presence of NADPH.

The effects of cytosol, NADPH and reduced glutathione (GSH) on the activity of 5'-deiodinase were studied by using washed hepatic microsomes from normal fed rats. Cytosol alone had little stimulatory effect on the activation of microsomal 5'-deiodinase. NADPH had no stimulatory effect on the microsomal 5'-deiodinase unless cytosol was added. 5'-deiodinase activity was greatly enhanced by the simultaneous addition of NADPH and cytosol (P less than 0.001); this was significantly higher than that with either NADPH or cytosol alone (P less than 0.001). GSH was active in stimulating the enzyme activity in the absence of cytosol, but the activity of 5'-deiodinase with 62 microM-NADPH in the presence of cytosol was significantly higher than that with 250 microM-GSH in the presence of the same concentration of cytosol (P less than 0.001). The properties of the cytosolic components essential for the NADPH-dependent activation of microsomal 5'-deiodinase independent of a glutathione/glutathione reductase system were further assessed using Sephadex G-50 column chromatography to yield three cytosolic fractions (A, B and C), wherein A represents pooled fractions near the void volume, B pooled fractions of intermediate Mr (approx. 13 000), and C of low Mr (approx. 300) containing glutathione. In the presence of NADPH (1 mM), the 5'-deiodination rate by hepatic washed microsomes is greatly increased if both A and B are added and is a function of the concentrations of A, B, washed microsomes and NADPH. A is heat-labile, whereas B is heat-stable and non-dialysable. These observations provide the first evidence of an NADPH-dependent cytosolic reductase system not involving glutathione which stimulates microsomal 5'-deiodinase of normal rat liver. The present data are consistent with a deiodination mechanism involving mediation by a reductase (other than glutathione reductase) in fraction A of an NADPH-dependent reduction of a hydrogen acceptor in fraction B, followed by reduction of oxidized microsomal deiodinase by the reduced acceptor (component in fraction B).

Animals↗