Publications (5)2.53 Total impact
Article: Corticosterone secretion in response to serotonin and acth by perfused adrenal of normal and athymic nude mice[show abstract] [hide abstract]
ABSTRACT: Adrenocortical secretory responses to chemical mediators and ACTH in GD1 ICR nu/nu (athymic) mice were compared with those in CD1 ICR (normal) mice. The bilateral adrenals of normal or athymic mice were perfused in situ with artificial medium equilibrated by 95% O2 + 5% CO2. Infusion of serotonin induced the secretory response of corticosterone significantly at 10 nM and markedly at 100 nM and the response at 1000 or 10000 nM declined as compared with that at 100nM in normal mice. Total corticosterone secretion in response to 100 or 1000 nM serotonin in athymic mice was about one fourth that in normal mice, respectively. Corticosterone responses to ACTH at the range of 10 to 300 pg/ml in athymic mice were comparable to those in normal mice. Infusion of histamine, platelet activating factor(PAF), or compound did not induce significant corticosterone response in both normal and athymic mice. The data suggest that the congenital defect of the thymus and/or hair causes the hyporesponsiveness of adrenocortical cells to serotonin although the adrenal cortex of athymic mice is able to perform its function in response to ACTH.Life Sciences 02/1995; · 2.53 Impact Factor
Article: Synthesis of different crystalline silver nanocomposites stabilized by an amphiphilic block copolymer[show abstract] [hide abstract]
ABSTRACT: A solution-phase route was devised to synthesize crystal Ag nanowires with the micellar in-situ of Ag+. Ag nanocrystals were synthesized by using amphiphilic block copolymer polystyrene-block-poly (acrylic acid) (PS–b–PAA) based on the flexibility of the copolymer chains and the complex effect of –COOH in the poly acrylic acid with Ag+ ion and Ag under ultrasonic irradiation. The crystal morphologies were changing from rods to dendrite crystals. The resultant nanoproducts were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD) and electron diffraction (ED). The results revealed that the size of the resulting Ag nanostructures prepared was strongly dependent on the initial concentration of the silver ion solution and the concentration of the copolymer. This work provides a simple route for the in situ synthesis of Ag nanostructures.Materials Letters. 62:1424-1426.
Article: Combined magnetic and chemical covalent immobilization of pectinase on composites membranes improves stability and activity[show abstract] [hide abstract]
ABSTRACT: The idea of preparing the surface of Fe3O4 layer preadsorbed on the “spherical polyelectrolyte brush” via layer-by-layer self-assembly approach receives special relevance in enzyme technology. “Spherical polyelectrolyte brush” of core–shell structure were prepared by grafting poly(sodium 4-styrenesulphonate) (PSStNa) from SiO2 nanoparticles via the surface-initiated atom transfer radical polymerization strategy. The silica-coated (PEI/Fe3O4)n support presents a very simple, mild, and time-saving process for enzyme immobilization. The kinetics of a model reaction catalyzed by the immobilized pectinase was finally investigated by the Michaelis–Menten equation. These particles, premodified with the layer of magnetic nanoparticles to impart a magnetic property and subsequently coated with polyelectrolyte multilayer, were repeatedly used as catalysts following their rapid and easy separation with a magnet. Besides simplicity and versatility, the ease of enzyme regeneration constitutes an additional benefit of this approach.Food Chemistry.
Article: Aluminum regulation of citrate metabolism for Al-induced citrate efflux in the roots of Cassia tora L.[show abstract] [hide abstract]
ABSTRACT: Aluminum-induced exudation of organic acid from plant roots has been proposed to be an important mechanism for Al tolerance. In search for the physiological basis of citrate efflux, the activities of several enzymes involved in citrate metabolism and internal citrate accumulation in the root tips of Cassia tora L. were examined. Results indicated that aluminum at 10–50 μM progressively stimulated activities of citrate synthase (CS, EC 184.108.40.206). A time-course experiment revealed that the increase in CS activities occurred within 3 h after the Al exposure, while the substantial citrate exudation began 6 h after Al treatment, suggesting that citrate exudation could be due to the increased CS capacity. By contrast, aconitase (Aco, EC 220.127.116.11) activities in Al-treated root tips were always suppressed compared with controls, indicating that aconitase was possibly involved in the aluminum-induced citrate efflux. The increase in CS activity and decrease in aconitase activity with Al treatments were associated with the enhanced citrate accumulation in root tips. We also examined NADP-isocitrate dehydrogenase (NADP-ICDH, EC 18.104.22.168), malate dehydrogenase (MDH, EC 22.214.171.124) and phosphoenolpyruvate carboxylase (PEPCase, EC 126.96.36.199) in root tips exposed to Al. However, none of the enzymes showed significant alterations in activities. These results suggested that NADP-ICDH, MDH and PEPCase were not directly involved in the Al-induced citrate exudation in the roots of C. tora.Plant Science.
Article: Chitosan-tethered the silica particle from a layer-by-layer approach for pectinase immobilization[show abstract] [hide abstract]
ABSTRACT: “Spherical polyelectrolyte brush” of core–shell structure were prepared by grafting poly (sodium 4-styrenesulphonate) (PSStNa) from SiO2 nanoparticle via the surface-initiated atom transfer radical polymerization strategy. The colloidal stability was not impeded by the adsorbed proteins despite the fact that up to 316.8 mg of enzyme was adsorbed per gram of the carrier particles. The immobilized pectinase revealed acceptable pH stability over a broad experimental range of 3.0–4.5. The activity half lives for native and bound states of enzyme were found as 13.5 d and 30 d, respectively. The activity of immobilized pectinase adsorbed onto these particles was analyzed in terms of the Michaelis–Menten parameters. Kinetic parameters were calculated as 8.28 and 9.98 g pectin ml−1 for Km and 1.165 × 10−3 g pectin s−1 g enzyme−1 1.124 × 10−3 g pectin s−1 g particle−1 for Vmax in the case of free and immobilized enzymes, respectively. Enzyme activity was found to be approximately 49.7% for immobilized enzyme after storage for 1 month.Food Chemistry.