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Biomedical subjects

B Xue

Publications and source records attributed to B Xue.

At least 19 recordsLinked to original sources
PubMed2003

Characterization of a MYBR2R3 gene from black spruce (Picea mariana) that shares functional conservation with maize C1.

PCR amplification with degenerate primers targeted to highly conserved amino acid motifs within the MYB domain was used to demonstrate that black spruce (Picea mariana) possesses a diverse MYB gene family. Amino acid sequence comparisons revealed three broad MYB subfamilies, one of which shares extensive similarity with maize C1, a central regulator of anthocyanin biosynthesis. A cDNA clone encoding a MYBR2R3 protein from P. mariana with high levels of sequence homology to maize C1 was shown to transactivate the Bz2 promoter in combination with maize R in embryonal tissues of both black spruce and larch. Functional dependence on the maize R protein, and the presence of a conserved C-terminal GIDPxTH motif, support the conservation of MYBR2R3 function in conifers, and demonstrate that the basic components of MYBR2R3-dependent transcriptional regulation have been conserved between angiosperms and gymnosperms.

Amino Acid Sequence↗
PubMed2001

Mechanism of intracellular calcium ([Ca2+]i) inhibition of lipolysis in human adipocytes.

We investigated the mechanisms responsible for the anti-lipolytic effect of intracellular Ca2+ ([Ca2+]i) in human adipocytes. Increasing [Ca2+]i inhibited lipolysis induced by b-adrenergic receptor activation, A1 adenosine receptor inhibition, adenylate cyclase activation, and phosphodiesterase (PDE) inhibition, as well as by a hydrolyzable cAMP analog, but not by a nonhydrolyzable cAMP analog. This finding indicates that the anti-lipolytic effect of [Ca2+]i may be mediated by the activation of adipocyte PDE. Consistent with this theory, [Ca2+]i inhibition of isoproterenol-stimulated lipolysis was reversed completely by the nonselective PDE inhibitor isobutyl methylxanthine and also by the selective PDE 3B inhibitor cilostamide, but not by selective PDE 1 and 4 inhibitors. In addition, phosphatidylinositol-3 kinase inhibition with wortmannin completely prevented insulin's anti-lipolytic effect but only minimally blocked [Ca2+]i's effect, which suggests that [Ca2+]i and insulin may activate PDE 3B via different mechanisms. In contrast, the antilipolytic effect of [Ca2+]i was not affected by inhibitors of calmodulin, Ca2+/calmodulin-dependent kinase, protein phosphatase 2B, and protein kinase C. Finally, [Ca2+]i inhibited significantly isoproterenol-stimulated increases in cAMP levels and hormone-sensitive lipase phosphorylation in human adipocytes. In conclusion, increasing [Ca2+]i exerts an antilipolytic effect mainly by activation of PDE, leading to a decrease in cAMP and HSL phosphorylation and, consequently, inhibition of lipolysis.

1-Methyl-3-isobutylxanthine↗
PubMed2001

Protein adsorption equilibria and kinetics to a poly(vinyl alcohol)-based magnetic affinity support.

A poly(vinyl alcohol)-based magnetic gel entrapping Fe3O4 colloids has been prepared by an emulsification-crosslinking method. The gel was modified with Cibacron blue 3GA, and thus a magnetic affinity support was produced. The adsorption equilibrium studies showed that the adsorption isotherm of lysozyme was nearly rectangular, with a capacity of 254 mg/ml, while the adsorption isotherm of bovine serum albumin obeyed the Henry's law. Uptake kinetics of the two proteins was investigated and analyzed with a pore diffusion model and a homogeneous diffusion model. Experimental results showed that the magnetic affinity gel had magnetic responsiveness and favorable properties in protein adsorption, and was mechanically and chemically stable.

Adsorption↗
PubMed2001

Agouti signaling protein stimulates islet amyloid polypeptide (amylin) secretion in pancreatic beta-cells.

Ectopic overexpression of the murine agouti gene results in yellow coat color, obesity, hyperinsulinemia, and type II diabetes. We have shown the human homologue of agouti (agouti signaling protein; ASP) to regulate human adipocyte metabolism and lipid storage via a Ca(2+)-dependent mechanism. We have also demonstrated agouti expression in human pancreas, and that ASP stimulates insulin release via a similar Ca(2+)-dependent mechanism. Plasma amylin is also elevated in agouti mutant mice. Amylin is cosecreted with insulin from beta-cells, and overexpression of human amylin in beta-cells in yellow agouti mutant mice resulted in accelerated pancreatic amyloid deposition, severely impaired beta-cell function, and a diabetic phenotype. We report here that ASP stimulates amylin release in both the HIT-T15 beta-cell line and human pancreatic islets in the presence of a wide range of glucose concentrations (0-16.7 mmol/L), similar to its effect on insulin release; this effect was blocked by 30 mumol/L nitrendipine, confirming a Ca(2+)-dependent mechanism. Accordingly, ASP stimulation of amylin release may serve as a compensatory system to regulate blood glucose in yellow agouti mutants.

Agouti Signaling Protein↗
PubMed2001

[The relationship between cadmium-induced inhibition of splenic lymphocyte function and cell apoptosis].

OBJECTIVE: To explore the relationship between cadmium-induced inhibition of splenic lymphocyte function and cell apoptosis in vitro. METHODS: The splenic lymphocytes of mice were exposed to 3.10, 6.25, 12.50, 25.00, 50.00 micromol/L of cadmiun chloride (CdCl(2)) for various time period, to measure the lymphocyte transformation by MTT colorimetric assay and to detect the apoptosis in splenocytes by DNA agarose electrophoresis and flow cytometry (FACS). RESULTS: CdCl(2) could significantly inhibit the function of lymphocyte transformation in a dose-response pattern at concentrations of 25.00 and 50.00 micromol/L, with inhibition rates of 50% and 78% in ConA-stimulating group and 39% and 55% in LPS-stimulating group, respectively. CdCl(2) could also induce apoptosis of splenic cells at concentrations of 12.50 to 50.00 micromol/L. RESULTS: of FACS analysis showed 30% - 60% of cell apoptosis. Higher concentration of CdCl(2) could also cause reduction of cell survival. Effect of Cd-induced apoptosis was earlier and at a lower concentration of CdCl(2) than that of Cd-induced inhibition of lymphocyte transformation. CONCLUSION: CdCl(2) could induce cell apoptosis in vitro, which was one of the mechanisms of its suppression of lymphocyte function.

Animals↗
PubMed2000

Collision relaxation cross section of highly vibrationally excited molecules

Through quantum-beat spectroscopy collision relaxation of a high vibrational level of SO2 at 44 877.52 cm(-1) is characterized. This is a first measurement of collision relaxation for a single, highly excited vibrational level. The deduced relaxation cross section of this excited level by Ar is 216 A(2), 5 times the area of the hard sphere, and by an ambient temperature SO2 molecule is 969 A(2), almost 20 times the hard sphere. These cross sections indicate that relaxation collisions of highly vibrationally excited molecules have effective distances much longer than van der Waals radii and involve mechanisms qualitatively different from lower excitations.

Journal Article↗
PubMed2000

Relationship between human adipose tissue agouti and fatty acid synthase (FAS).

The human homologue of the murine obesity gene, agouti, is expressed in adipose tissue. We have shown that recombinant agouti protein regulates adipocyte lipogenesis and lipolysis coordinately and promotes lipid storage via a Ca(2+)-dependent mechanism in vitro, which may contribute to agouti-induced obesity. However, little is known about agouti's physiologic function in humans. We first studied the agouti content in human mature adipocytes vs. preadipocytes. The agouti content of human mature adipocytes was five times as abundant as in preadipocytes (19.18 +/- 2.46 vs. 4.07 +/- 0.51 pg/microg protein, P: < 0.005), suggesting that agouti is up-regulated during adipocyte differentiation. We next studied the relationship of agouti mRNA and protein to fatty acid synthase (FAS) mRNA and activity in adipose tissue obtained from nonobese and mildly obese patients (body mass index range, 21-31 kg/m(2)). Agouti protein was correlated with FAS activity (r = 0.782, P: < 0.005). Similarly, human adipose tissue agouti mRNA level was also correlated with FAS mRNA level (r = 0.846, P: < 0.001). These data suggest that agouti may be another adipocyte-produced factor that modulates adipocyte lipid metabolism via a paracrine/autocrine mechanism.

Adipocytes↗
PubMed2000

[Effect of sodium azide on mitochondrial membrane potential in SH-SY5Y human neuroblastoma cells].

OBJECTIVE: To study the role of mitochondrial deficiency in the pathogenesis of neurodegenerative disease by investigating the energy metabolism in a sodium azide inhibited cytochrome-c oxidase SH-SY5Y Cell model. METHODS: Human neuroblastoma SH-SY5Y Cells were exposed to sodium azide, then mitochondrial complex IV activity was assayed by microassay method; cell viability was measured by Thiazolyl blue(MTT) method; mitochondrial membrane potential (MMP) was detected by confocal microscopy and flow cytometry. RESULTS: Cultured SH-SY5Y cells were exposed to 16-64 mmol/L sodium azide for 1 hour, the mitochondrial complex IV activity decreased dose-dependently. MTT absorbance decreased does- and time-dependently in cultured nerve cells treated by 16-128 mmol/L sodium azide for 1-8 hours. After the treatment of 16 mmol/L sodium azide for 1 hour, both the fluorescence intensity of MMP and normal cell events reduced. Decrease of MMP was significant especially in cell processes. CONCLUSION: Sodium azide induced the impairment of mitochondrial energy synthesis in the cultured nerve cells which is an important cause in cell death.

Cell Death↗
PubMed1999

[The change in bacterial flora and antibiotic resistance of bacteria of burn patients in our hospital during 1986-1996].

OBJECTIVE: In this article we investigated and analyzed the pathogenetic bacteria of burn infection and their drug resistance in recent 5 years from 1991. METHODS: The patients are divided into 2 groups. The 1st group is from June 1986 to May 1991, and the 2nd group is from June 1991 to June 1996. Blood culture and burn wound bacteria culture were done, and bacteria and their drug sensitivity were analyzed. RESULTS: In blood culture, Micrococcus had risen to rank the top (21.6%), while Staphylococcus aureus fell to rank the third. Among these G+ cocci comprised 56.5%, and G- bacilli 30.1%. In burn wound culture, Pseudomonas aeruginosa with rate of 18.1% was still in the 1st place. Enterobacter cloacae was in the 2nd place with the rate of 13.1%. Among these G- bacilli comprised 58.6%, G+ cocci 35.3%. Micrococcus enterobacter cloacae, Pseudomonas maltophilia, fecal Staphylococcus and candida albicans increased remarkably. CONCLUSION: The changes of pathogenetic bacteria of burn infection and bacteria drug resistance have certain relations with the wide usage of broad spectrum antibiotics such as cefazidime and imipenem.

Actinomycetales Infections↗
PubMed1999

[Analysis of the protein of Haemophilus influenzae].

OBJECTIVE: To understand Haemophilus influenzae special protein and to help for preparing Haemophilus influenzae Vaccine. METHODS: Proteins from isolates of Haemophilus influenzae were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS: 23 isolates were from nasopharyngeal secretions of children with pneumonia and 33 from pharyx swab of healthy children. Conventional tests showed that 79% of fifty-six strains of Haemophilus influenzae were non-serotypable and all belonged to one of eight biotypes. The common biotypes were II (48%). All strains contained more than 10 proteins with molecular weights of 96,000, 86,000, 55,000, 51,000, 46,000, 40,000, 39,000, 31,000, 29,000, 25,000, and 16,000. Among them, three were major proteins (31,000, 51,000 and 96,000) and different proteins were mainly between peptide 31,000 and 51,000. A possible association between biotype and protein was unclear. CONCLUSION: Analysis of protein of Haemophilus influenzae is helpful for epidemiological study of non-serotypable Haemophilus influenzae and making Haemophilus influenzae vaccine.

Bacterial Proteins↗
PubMed1999

[Synergistic interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines in vitro].

OBJECTIVE: To study in vitro the anticancer interaction between Ys-96, a bisbenzylisoquinoline compound derived from Stephania tetrandra, and adriamycin or vincristine against human cancer cell lines. METHOD: Using human breast cancer cell MCF-7 and its adriamycin-resistant cell line MCF-7/Adr, and human nasopharyngeal cancer cell KB and its vincristine-resistant cell line KBv200 in an in vitro system, anticancer interaction between Ys-96 and adriamycin or vincristine was evaluated with a method reported by Berenbaum. RESULT: The SFIC values (sum of fractional inhibitory concentration) of the combinations with 3 different ratios between Ys-96 and adriamycin or vincristine were markedly less than 1.0, and the shapes of all the isobologram curves were concave. CONCLUSION: The synergistic interaction between Ys-96 and adriamycin or vincristine against the above human cancer cell lines was positively observed in vitro.

Antineoplastic Agents, Phytogenic↗
PubMed1999

[A study on hemostatic and immunological actions of fresh and dry Dihuang].

OBJECTIVE: To investigate the difference between fresh and dry Dihuang (Radix Rehmanniae) in hemostatic and immunological actions. METHODS: The hemostatic action was assessed in aspirin-treated mice; immunological action was assessed by phagocytosis of macrophages in dexamethasone-treated mice; and Con A-induced mitogenesis and LPS-induced alkaline phosphatase activity of splenocytes were determined in thyroxin-treated mice. RESULT: The blood clotting in mice induced by aspirin was inhibited by oral administrations of juice decoction of fresh Dihuang or decoction of dry Dihuang alike. The action of fresh Dihuang juice was stronger than that of dry Dihuang decoction. Oral administrarion of fresh Dihuang juice or decoction for 10 days enhanced LPS-induced alkaline phosphatase activity of splenocytes in thyroxin-treated mice. The juice also enhanced Con A-induced splenocyte mitogenesis. The action of dry Dihuang decoction was weaker than that of fresh juice in increasing LPS-induced alkaline phosphatase activity. CONCLUSION: It is recommended to follow the tradition of using fresh Dihuang juice or decoction to treat some diseases such as hemorrhagenic troubles.

Animals↗
PubMed1998

[Effects of cadmium chloride on the function of peritoneal macrophage in mice].

OBJECTIVE: To study the effects of cadmium on macrophage function. METHODS: Many indicators, such as phagocytic function, abilities to produce nitrous oxide and hydrogen peroxide, in mice were determined 14 days after they were administered continuously with 0.3, 0.6 and 1.2 mg/kg cadmiuCell count decreased in the mouse peritoneal lavage with the effects of cadmium chloride, with a significant difference, as compared with the control group. Phagocytic function of macrophage was inhibited significantly, with inhibition rates of 21.8%, 39.9% and 44.4%, respectively for various doses of cadmium, in a dose-response pattern. The ability of microphage to produce nitrous oxide was significantly inhibited, also, with 61.90 +/- 27.83, 36.67 +/- 23.86, 46.60 +/- 13.33 mumol/L, respectively, as compared with 76.10 +/- 14.22 mumol/L in the control group. The ability of microphage to produce O2.- was obviously inhibited by three different doses of cadmium, showing a dose-response relationship (r = 0.9790). The ability of microphage to produce hydrogen peroxide was inhibited only at a dose of 1.2 mg/kg of cadmium, with a significant difference as compared with the control group. There was a dose-response relationship between cadmium and production of hydrogen peroxide, with a coefficient of regression (r) of -0.9847. CONCLUSION: Cadmium chloride, at the doses of 0.3, 0.6 and 1.2 mg/kg, could inhibit the phagocytic function of microphage, and the production of biological molecules, such as nitrous oxide, O2.- and hydrogen peroxide. It indicated that cadmium chloride could directly affect the transmission of antigen and non-specific defence function of macrophage.

Animals↗
PubMed1998

A clinical study on bing gan ling oral liquid for treatment of hepatitis C.

Based on the principles of cooling the blood to expel the pathogenic toxins and regulating the function of liver and activating the spleen in traditional Chinese medicine, 60 cases of chronic hepatitis C were treated with Bing Gan Ling (BGL), an oral liquid, which is composed mainly of Shuiniujiao (Cornu Bubali), Huzhang (Rhizoma Polygoni Cuspidati), Chishao (Radix Paeoniae Rubra), and Huangqi (Radix Astragali), etc. The total effective rate was 86.7%, which is considerably better than that of the control group (P < 0.01). The animal experiments and pathological studies suggest that the above-mentioned prescription has marked action of protecting the liver and lowering the activity of enzymes; and that it can ameliorate the acute liver injury induced by D-galactosamine.

Adult↗
PubMed1998

[Reversal effect of Ys-96, a bisbenzylisoquinoline, on adriamycin or vincristine resistance in human cancer cells in vitro].

OBJECTIVE: Reversal effect of Ys-96, a bisbenzylisoquinoline, on the resistance of human cancer cells to adriamycin or vincristine was studied in vitro. METHOD: In an in vitro culture system of human cancer cells MCF-7 and its adriamycin-resistant line MCF-7/Ad or KB and its vincristine-resistant line KBv200, the sensitivity(IC50) of the resistant cell lines to adriamycin or vincristine was evaluated with a MTT assay. RESULT: IC50 value of adriamycin or vincristine in combination with Ys-96 at a concentration of 1.00 mumol/L against MCF-7/Ad or KBv200 was found to be close to that of adriamycin alone or vincristine alone against the sensitive cell line MCF-7 or KB. CONCLUSION: The drug resistance of MCF-7/Ad or KBv200 could be essentially reversed by Ys-96 at a concentration of 1.00 mumol/L.

Benzylisoquinolines↗
PubMed1998

The agouti gene product inhibits lipolysis in human adipocytes via a Ca2+-dependent mechanism.

Overexpression of the murine agouti gene results in obesity. The human homologue of agouti is expressed primarily in human adipocytes, and we have shown recombinant agouti protein to increase adipocyte intracellular Ca2+([Ca2+]i) and thereby stimulate lipogenesis. However, since recent data demonstrate that increasing adipocyte [Ca2+]i may also inhibit lipolysis, we have investigated the role of agouti-induced [Ca2+]i increases in regulating lipolysis in human adipocytes. Short-term (1 h) exposure to recombinant agouti (100 nM) protein had no effect on basal lipolysis, although longer term treatment (24 h) caused a 60% decrease in basal lipolysis (P<0.0001). Short-term agouti treatment totally inhibited ACTH-induced lipolysis (P<0.05). Since melanocortin receptors (MCR) are involved in some actions of agouti, we next determined whether agouti's antilipolytic effect is exerted through competitive antagonism of the ACTH receptor (MCR-2). Forskolin (1 microM), an adenylate cyclase activator, induced a 48% increase in lipolysis in human adipocytes (P<0.05); this effect was reversed by 100 nM agouti (P<005), demonstrating that the antilipolytic effect of agouti is distal to the ACTH receptor. To determine the role of [Ca2+]i in the antilipolytic effect of agouti, human adipocytes were treated with KCl or arginine vasopressin to stimulate voltage- and receptor-stimulated Ca2+ influx, respectively. Both agents caused inhibition of forskolin-induced lipolysis (P<0.005). Furthermore, agouti's antilipolytic effect was also blocked by the Ca2+ channel blocker nitrendipine. These data demonstrate that agouti exerts a potent antilipolytic effect in human adipocytes via a Ca2+-dependent mechanism. This effect, combined with agouti-induced lipogenesis, represents a coordinate control of adipocyte lipid metabolism that may contribute to an agouti-induced obesity syndrome.

Adenosine Triphosphate↗