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Biomedical subjects

H Shimada

Publications and source records attributed to H Shimada.

At least 883 records · Page 49Linked to original sources
PubMed1984

J chain synthesis and ultrastructural changes in chronic lymphocytic leukaemia cells during in vitro differentiation.

The synthesis of J chain and the ultrastructural changes in chronic lymphocytic leukaemia (CLL) cells during in vitro cultures stimulated with PWM and/or allogenic T cells were investigated by immunoelectron microscopy, radioimmunoassay and anti-idiotype antibodies, in an attempt to demonstrate changes in the maturation stage of CLL cells. The cells from four patients showed the induction of J chain synthesis in parallel with the increase of Ig synthesis. Two of revealed cytological transformations, in which CLL cells resembled immunoblasts or plasmacytoid cells. These findings suggest that some CLL cells are not 'frozen' within the original maturation stage and can be induced to differentiate to a more mature stage.

Cell Differentiation↗
PubMed1984

Rapid modulation of platelet aggregation in plasma by oxygenated sterols.

The effect of oxygenated sterols on platelet aggregation induced by thrombin and ADP has been studied. All oxygenated sterols tested with a hydroxyl group on the side chain enhanced thrombin-induced aggregation at 25 microM. In the case of ADP-induced aggregation, however, only 22S-hydroxycholesterol[(22S)-5-cholestene-3 beta,22-diol] enhanced the aggregation, and 22R-hydroxycholesterol[(22R)-5-cholestene-3 beta,22-diol], 24S-hydroxycholesterol[(24S)-5-cholestene-3 beta,24-diol], and 25-hydroxycholesterol[5-cholestene-3 beta,25-diol] inhibited it. These effects were observed within 10 min after the addition of oxygenated sterols to platelet suspensions in plasma.

Adenosine Diphosphate↗
PubMed1983

Agonist-specific refractory states of bovine platelets-disappearance of synergism in aggregation.

The specificity of refractory state of bovine platelets developed by various agonists was examined. When bovine unwashed platelets were preincubated with 5-hydroxytryptamine (5HT) (or ADP), they became non responding to that agonist (refractory) but they responded quite normally to collagen, thrombin and ADP (or 5HT). When platelets became refractory to 5HT, the synergistic aggregation normally obtained with this agonist plus ADP was lost, but that with ADP plus thrombin was not changed. Platelets made refractory to ADP (or 5HT) after the aggregation and disaggregation cycle by the agonist responded normally to 5HT (or ADP). These results strongly indicate that platelets become refractory to one agonist without impairing the sensitivity to any other agonists.

Adenosine Diphosphate↗
PubMed1983

Proton coupling in the ligand-binding reaction of ferric cytochrome P-450 from Pseudomonas putida.

Effects of pH on the ligand-binding reactions of ferric heme in cytochrome P-450 from Pseudomonas putida (camphor 5-monooxygenase, EC 1.14.15.1) were studied by using cyanide, N-methylimidazole, pyridine, and ethylisocyanide as ligands. In all cases, affinity of the ferric heme for the ligand was found to increase as pH of the medium was raised from around 6 to 9. Depending on the ligand, the increase was 10- to 1000-fold and the shapes of their pH-affinity curves were remarkably different. Analyses such pH profiles disclosed the presence of a dissociable group in the enzyme with a pK value of approximately 9.5 and that its ionization greatly enhanced the affinity of the heme for ligands. When a dissociable ligand such as hydrogen cyanide and N-methylimidazole was used, the dissociated form of the ligand had a higher affinity toward the heme than the undissociated form. The shapes of the pH-affinity curves were successfully simulated as overlapping curves of ionization reactions of the ligand and the dissociable group. In addition, size of the ligand molecule was shown to be also important in the binding reaction: relatively large molecules such as pyridine, ethylisocyanide, and N-methylimidazole bound to the enzyme in a competitive manner against d-camphor concentration, whereas the binding of a smaller molecule such as cyanide was inhibited by the substrate in a noncompetitive manner. On the basis of these findings, control mechanisms for the ligand-binding reactions of the cytochrome P-450 from P. putida are discussed.

Bacterial Proteins↗
PubMed1983

Inhibition of DNA polymerases of sea urchin by palmitoyl coenzyme A.

Palmitoyl CoA noncompetitively inhibited the activities of DNA polymerase alpha and gamma, prepared from sea urchin germ cells, with Ki values of 28 microM and 116 microM, respectively. Myristoyl CoA also inhibited DNA polymerase alpha and gamma, while coenzyme A, short chain fatty acyl CoA's, Na-myristate and Na-palmitate failed to inhibit the enzymes. It was concluded that both the long hydrocarbon chain and CoA moiety of long chain fatty acyl CoA's are necessary for inhibition of DNA polymerase activity. DNA polymerase beta was not inhibited by long chain fatty acyl CoA's.

Acyl Coenzyme A↗
PubMed1983

Effects of guanine nucleotides on vasopressin-induced water flow and sodium transport of the frog bladder.

In the present study, we examined the effects of guanine nucleotides on vasopressin-induced osmotic water flow and sodium transport in the 14-h preincubated frog bladder. We also examined the effects of the adenylate cyclase-cyclic AMP and cyclic AMP-dependent protein kinase system in the bladder's epithelial cells. Gpp(NH)p significantly enhanced vasopressin-induced water flow while it did not affect cyclic AMP-induced water flow. However, Gpp(NH)p did not enhance the vasopressin-induced increment of sodium transport across the frog bladder. The adenylate cyclase activity of the crude homogenate was enhanced by vasopressin, Gpp(NH)p and NaF. The effects of Gpp(NH)p and vasopressin, at their maximum doses, on the enzyme activities were additive, while other combinations were not. Specific Gpp(NH)p binding sites were found in the pellet fraction after 2,400 X g centrifugation. No direct effect on the protein kinase activity was observed in the presence of 10(-6) M nucleotides, such as GTP, GDP, GMP, CTP, UTP, ITP and Gpp(NH)p. Cyclic AMP stimulated the phosphorylation of discrete protein bands, however, Gpp(NH)p did not influence cyclic AMP-dependent protein phosphorylation of crude homogenate of the bladder's epithelial cells. These results suggest the guanine nucleotides stimulate the vasopressin-induced osmotic water flow in frog bladder by enhancing the vasopressin-mediated adenylate cyclase activity, so that accumulated cyclic AMP might activate cyclic AMP-dependent protein kinase.

Adenylyl Cyclases↗
PubMed1983

Extraction of retained gallstones using a fiber-choledochoscope through a PTC-drainage fistula.

After unsuccessful attempts to completely remove gallstones, endoscopic papillotomy was carried out to remove the stones after closure of the T-tube tract. We treated two patients with successful extraction of retained gallstones using a fiber-choledochoscope through a percutaneous transhepatic cholangio-drainage (PTCD) fistula. This technique can be applied in cases when endoscopic papillotomy cannot be performed or for patients who are poor risks for repeat surgery.

Biliary Tract↗
PubMed1983

Cellular factor stimulating DNA synthesis in nuclei isolated from sea urchin embryos.

DNA synthesis in isolated nuclei of morula-stage embryos of sea urchin was studied. Embryonic extracts of cleaving embryos (but not unfertilized eggs) stimulated DNA synthesis in the in vitro system. A stimulatory factor was identified which eluted at 0.52 M KCl during chromatography on DEAE-cellulose column. This factor was inactivated by heat treatment and trypsin digestion, and was resolved into three active peaks by gel filtration (Strokes radii of 6.3, 4.6, and 4.1 nm, respectively).

Animals↗
PubMed1983

Effects of emetine on initiation of DNA synthesis in embryonic cells of sea urchin.

The effects of the inhibition of protein synthesis by emetine on the initiation of DNA synthesis and mitosis in the fertilized eggs of the sea urchin, Anthocidaris crassispina, were studied. The initiation of DNA synthesis was completely prevented, and no delayed initiation was observed in eggs in which protein synthesis was completely inhibited by emetine, while delayed initiation of DNA synthesis occurred after prolonged culture in eggs in which protein synthesis was incompletely inhibited by emetine. In both cases, neither mitosis nor cleavage was observed. Synthesis of some protein factor seems to be necessary for the initiation of DNA synthesis.

Animals↗
PubMed1983

Characterization of glycoproteins isolated from porcine zonae pellucidae.

Two glycoproteins, tentatively designated as PZ-alpha and PZ-beta, have been isolated and purified to homogeneity from porcine zonae pellucidae by a simple purification procedure producing a high yield. The procedure included the dissolution of the zona material in 0.1 M sodium borate buffer pH 10.0, Sephadex G-100 column chromatography and preparative SDS-polyacrylamide gel electrophoresis. The purified glycoproteins gave a single band on polyacrylamide gel and had molecular weights of 60 000 (PZ-alpha) and 96 000 (PZ-beta). Glutamic acid was detected as the NH2-terminal residue in both glycoproteins, using the dansyl chloride method. Though their amino acid compositions were similar, their carbohydrate contents were slightly different (PZ-alpha: 24.9%; PZ-beta; 19.6%), but these components contained the same types of monosaccharides: fucose, mannose, galactose, NAcGlc and sialic acid. The antigenic properties of the two glycoproteins were indistinguishable by immunodiffusion tests. The PZ-beta could be converted in part to smaller molecular weight components, though not to PZ-alpha, by treatment with beta-mercaptoethanol. Thus clear differences between PZ-alpha and PZ-beta could not be detected by chemical or immunological analyses except for the difference in the behaviour on SDS-polyacrylamide gel electrophoresis.

Amino Acids↗
PubMed1983

Inhibitory effect of long chain fatty acyl CoAs on RNA polymerase from Escherichia coli.

RNA polymerase from Escherichia coli was inhibited by long chain fatty acyl CoAs, such as myristoyl CoA (Ki = 17.2 microM), palmitoyl CoA (Ki = 8.9 microM), oleoyl CoA (Ki = 5.5 microM), and stearoyl CoA (Ki = 0.94 microM). The inhibition by these CoA thioesters was non-competitive against nucleoside triphosphates. Short chain fatty acyl CoAs, such as acetyl CoA, propionyl CoA, acetoacetyl CoA, butyryl CoA, and decanoyl CoA, failed to inhibit RNA polymerase. CoA, Na-myristate, Na-palmitate, Na-oleate, Na-stearate, palmitoyl carnitine, and carnitine did not inhibit the enzyme. The inhibition of RNA polymerase by long chain fatty acyl CoAs was competitive against template DNA.

Acyl Coenzyme A↗
PubMed1983

Influence of aluminium on the effect of 1 alpha (OH)D3 on renal osteodystrophy.

The influence of aluminium in dialysate on the effects of 1 alpha (OH)3 on hemodialyzed hypocalcemic patients with end-stage renal failure, was studied during a 24- to 42-month period. 51 hypocalcemic patients were divided into two groups; group 1 consisted of 28 patients who were dialyzed using dialysate prepared from reverse osmosed water; the 23 patients in group 2 used dialysate prepared from softened water. Aluminium concentration in the dialysate used for group 1 was less than the detectable limit (10 micrograms/l) in twelve times determinations, while that for group 2 was 23.1 +/- 9.2 micrograms/l (mean +/- SD, n = 14). By the administration of 1 alpha (OH)D3, the serum concentration of calcium was increased, and that of iPTH and alkaline phosphatase activity was decreased in both groups. Subperiosteal resorption of the finger bone, evaluated by Jensen's criteria, was significantly improved in group 1, while there was no improvement in group 2. Serum aluminium concentration in the patients of group 1 and group 2 were 46.6 +/- 6.3 and 84.7 +/- 13.9 micrograms/l, respectively, and the concentration of the latter was significantly higher than that of the former (p less than 0.01). It was also shown that there is a positive correlation between the extent of subperiosteal resorption and the concentration of aluminum in serum. Serum aluminium concentration and bone aluminium content were increased according to the duration of hemodialysis in the patients who were dialyzed using dialysate from softened water, while there was no correlation between the duration of hemodialysis and serum aluminium concentration for the patients of group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Plasminogen activator in rat ovary during the ovulatory process: independence of prostaglandin mediation.

To elucidate the possible roles of increased plasminogen activator (PA) in follicular rupture and to investigate whether prostaglandins participate in ovarian PA synthesis in vivo, enzyme activities were sequentially measured by a method using the chromogenic substrate S-2251 in immature rat ovaries primed with pregnant mare serum gonadotrophin (PMSG) followed by human chorionic gonadotrophin (hCG) either alone or with a concurrent injection of indomethacin. Before hCG injection PA activity was 0.006 +/- 0.006 (S.D.) mumol/1.6 mg ovarian tissue (wet wt) per 30 min: PA activity of a saline-treated group remained at low levels (less than 0.018 +/- 0.003 mumol/l X 6 mg tissue per 30 min). In contrast, PA activity of animals given hCG alone increased after the treatment, reaching a peak value of 0.112 +/- 0.071 mumol/l X 6 mg tissue per 30 min 12h later, before decreasing to 0.023 +/- 0.014 mumol/l X 6 mg tissue per 30 min at 32 h. Contrary to expectations, a dose of indomethacin which completely blocked ovulation had no effect on either the magnitude or the time-course of PA synthesis after hCG administration (P greater than 0.05). These results indicate that prostaglandins are not involved in the preovulatory synthesis of PA induced by hCG in rat ovaries and that PA is not a primary proteolytic enzyme for follicular rupture. It is suggested that PA has possible roles in cumulus detachment and/or proliferation of granulosa cells during the ovulatory process.

Animals↗