Lectin-binding patterns in the developing tooth

The lectin-binding patterns of the cells involved in amelogenesis and dentinogenesis in developing teeth of rats were studied. Undifferentiated odontogenic epithelia exhibited very slight staining with almost all of the lectins examined. The lectin-staining affinities of secretory ameloblasts could be divided into two categories: Concanavalin-A (Con-A), Wheat germ agglutinin (WGA) and Soybean agglutinin (SBA) binding occurred from the middle to apical cytoplasm, whereas Ricinus communis agglutinin-I (RCA-I) and Ulex europeus I (UEA-I) binding predominated in the basal regions. The cells of the stratum intermedium exhibited relatively strange lectin staining, which appeared to be dependent on ameloblastic maturation. The basement membranes in undifferentiated epithelia were markedly positive for lectin binding. Odontoblasts showed moderate Con-A staining on the apical side of the cells, as well as slight-to-moderate reactions with WGA and SBA. Pulp cells and dental papillae showed slight-to-moderate lectin staining, and predentin and dentin were also moderately positive for Con-A and RCA-I binding and slightly so for WGA and SBA. The lectin-binding affinities were enhanced during the formation of enamel and dentin, and appeared to be dependent on the degree of cellular differentiation in ameloblasts and odontoblasts.     

Shear Stress-induced Redistribution of Vascular Endothelial-Protein-tyrosine Phosphatase (VE-PTP) in Endothelial Cells and Its Role in Cell Elongation

Vascular endothelial cells (ECs) are continuously exposed to shear stress (SS) generated by blood flow. Such stress plays a key role in regulation of various aspects of EC function including cell proliferation and motility as well as changes in cell morphology. Vascular endothelial-protein-tyrosine phosphatase (VE-PTP) is an R3-subtype PTP that possesses multiple fibronectin type III-like domains in its extracellular region and is expressed specifically in ECs. The role of VE-PTP in EC responses to SS has remained unknown, however. Here we show that VE-PTP is diffusely localized in ECs maintained under static culture conditions, whereas it undergoes rapid accumulation at the downstream edge of the cells relative to the direction of flow in response to SS. This redistribution of VE-PTP triggered by SS was found to require its extracellular and transmembrane regions and was promoted by integrin engagement of extracellular matrix ligands. Inhibition of actin polymerization or of Cdc42, Rab5, or Arf6 activities attenuated the SS-induced redistribution of VE-PTP. VE-PTP also underwent endocytosis in the static and SS conditions. SS induced the polarized distribution of internalized VE-PTP. Such an effect was promoted by integrin engagement of fibronectin but prevented by inhibition of Cdc42 activity or of actin polymerization. In addition, depletion of VE-PTP by RNA interference in human umbilical vein ECs blocked cell elongation in the direction of flow induced by SS. Our results suggest that the polarized redistribution of VE-PTP in response to SS plays an important role in the regulation of EC function by blood flow.     

Synthesis of (S)-2-Hydroxy-β-ionone,Employing (S)-3-Hydroxy-2,2-dimethylcyclohexanone as the Chiral Starting Material

(S)-2-Hydroxy-β-ionone of 96% e.e. was synthesized from (S)-3-hydroxy-2,2-dimethyl cyclohexanone, which was easily obtained by the baker’s yeast reduction of 2,2-dimethylcyclohexane-l,3-dione.     

Isolation and characterization of hemorrhagic factors a and b from the venom of the Chinese habu snake (Trimeresurus mucrosquamatus)

Hemorrhagic factors a and b were isolated from Trimeresurus mucrosquamatus venom by Sephadex G-100, CM-Sephadex C-50 and DEAE-Sephacel column chromatographies. The hemorrhagic factors were homogeneous, as established by a single band on acrylamide gel electrophoresis, isoelectric focusing and sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Molecular weights of 15 000 and 27 000 were found for hemorrhagic factors a and b, respectively. Factor a possesses proteolytic activity hydrolyzing the His(10)-Leu(11), Tyr(16)-Leu(17) and Arg(22)-Gly(23) bonds of oxidized insulin B chain, whereas, factor b hydrolyzed only the Ala(14)-Leu(15) bond. Hemorrhagic activity of these hemorrhagic factors was inhibited by ethylenediaminetetraacetic acid, 1,10-phenanthroline or p-chloromercuribenzoate, but not by soybean trypsin inhibitor or diisopropyl fluorophosphate. The hemorrhagic factors were injected into the skin of the back of albino rabbits, and the minimum hemorrhagic dose of factors a and b was 1.7 and 2.3 micrograms, respectively. These purified hemorrhagic factors were not lethal at 15 micrograms/g in mice. Factor a hydrolyzed the B beta chain of fibrinogen, while factor b hydrolyzed the A alpha chain. Hemorrhagic factor a was shown to differ immunologically from factor b. Factors a and b produced systemic hemorrhage in internal organs such as the heart and stomach of mice. Moreover, factor b produced hemorrhage in the liver.     

Regulation of thymidine kinase activity in mouse L cells biochemically transformed by varicella-zoster virus

Regulation of thymidine kinase (TK) activity was examined in L(O)c133 and L(H3) cells carrying varicella-zoster virus-TK gene. TK activity of L(O)c133 cells was similarly high in either medium but that of L(H3) cells was high in HAT medium and low in non-HAT medium. Cell growth was well correlated with TK activities of L(O)c133 and L(H3) cells in medium conditions. Regulation of the TK gene in L cells carrying the VZV-TK gene is discussed.     

False positive reaction for carcinoembryonic antigen in Paget cells. Immunohistochemical observation

Paget cells from cases of mammary and extramammary Paget's disease were examined for carcinoembryonic antigen (CEA) and CEA-related antigens by the immunoperoxidase method. Paget cells showed a conspicuous positive reaction with antiserum to CEA, but were negative when nonspecific cross-reacting-antigen (NCA)-absorbed antiserum to CEA, or a monoclonal antibody to CEA was used as the detecting agents. Paget cells may contain large amounts of NCA antigen or CEA-related substances.     

Synthesis of acyclonucleosides of imidazole and purine series

In order to search for improved syntheses of 9-(2-hydroxyethoxymethyl) guanine and related antiviral agents, we tried several well documented general procedures (viz., fusion method) for the synthesis of N-glycosyl bond. Product distribution on alkylation of 4,5-disubstituted imidazoles as well as 2,6-disubstituted purines may depend upon the nature of alkylating agents (viz., 2-oxa-1,4-butanediol diacetate or 1-bromo-2-oxa-4-butanol acetate) and reaction conditions. A procedure for the synthesis of acyclovir and its N2-acetyl derivative could be improved to a considerable extent.