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Biomedical subjects

G L Xia

Publications and source records attributed to G L Xia.

13 recordsLinked to original sources
PubMed2000

Short time priming of pig cumulus-oocyte complexes with FSH and forskolin in the presence of hypoxanthine stimulates cumulus cells to secrete a meiosis-activating substance.

This study evaluated the effect of forskolin and FSH on pig oocyte maturation when cultured in a maturation inhibiting system. Ovaries from prepubertal gilts were collected at a local slaughterhouse. Oocytes were cultured in a hypoxanthine (HX 4 mM) containing M 199 for 24 or 40 h with or without forskolin and FSH treatment. After the culture, we examined germinal vesicle breakdown (GVBD) and polar body (PB) formation. Two experiments were designed. (1) Cumulus enclosed oocytes (CEO) were cultured for 24 or 40 h with or without different doses of forskolin and FSH. (2) CEO were primed by forskolin and FSH for different times and then transferred into an HX-medium for a further culture. The total culture period was 24 h. The results revealed that 4 mM HX markedly prevented pig CEO from undergoing GVBD. After 24 and 40 h culture, FSH (50-200 U/L) stimulated oocytes to resume meiosis by overcoming the inhibition of HX. Both GVBD and PB formation were increased (P < 0.002 and 0.01 respectively) after 40 h exposed to FSH. Forskolin showed a biphasic effect on CEO maturation. Within 24 h forskolin, in combination with HX, inhibited oocytes maturation. The GVBD percentage was significantly decreased compared to HX alone group (2% to 20%, P < 0.01), whereas no inhibition was observed after 40 h of culture. The second experiment showed that forskolin (3 microM) and FSH (100 U/L) priming CEO could time-dependently induce oocyte maturation by overriding the inhibition of HX. After 30 and 60 min priming by FSH or forskolin, the GVBD and PB percentage was significantly increased (P < 0.002 and 0.01 respectively). No difference of GVBD percentage was observed between FSH short time priming group and FSH long time presentation group. In conclusion, we found that forskolin and FSH in vitro can stimulate pig cumulus cells to secrete a meiosis-activating substance which induces the oocyte to overcome the inhibition of hypoxanthine and undergo GVBD.

Animals↗
PubMed2000

Induction of xenotransplant tolerance.

Clinical xenotransplantation will depend on the induction of xeno-tolerance. Conversely, xenotransplantation may offer opportunities to induce transplantation tolerance. We have previously shown that, xenotransplant tolerance for vascularized hamster organs could be achieved in athymic rats as far as the T-cell independent xeno-reactivity is concerned. This tolerance was shown to be based on specific T-independent B lymphocyte and NK cell unresponsiveness. In the present study we have shown that this T-independent xeno-tolerance can be achieved also in a semi-discordant situation using rat recipients with high titers of pre-existing anti-hamster IgM xenoantibodies. In addition, we showed that T-independent xeno-tolerance can also be induced together with T-dependent xeno-tolerance using xeno-thymus transplantation. These experiments may be of relevance for clinical xenotransplantation. The major next question to be addressed is to see how self tolerance in xeno-thymus grafted recipients can be improved as until now the latter recipients usually develop a multi-organ autoimmune syndrome, several weeks after transplanting a xeno-thymus.

Animals↗
PubMed2000

[The regulating mechanism of anti-fungicides on mouse oocyte development].

AIM: To study the mechanism of the effect of gonadotropin-induced oocyte maturation. METHODS: Mouse oocytes were cultured in HX-medium, and the effects of amphotericin B and ketoconazole on resumption of meiosis of mouse oocyte were examined. RESULTS: 1. FSH(10-200 IU/L) induced a dose-dependent manner of oocytes maturation in CEO. A maximum increase in GVBD was observed with 25-50 IU/L FSH. 2. Amphotericin tericim B (0.025-2.5 micrograms/L) caused significant increases in GVBD in CEO, which mimicked the function of FSH. 3. Ketoconazole (10(-7)-10(-3) mol/L) inhibited the effect of FSH on resumption of meiosis, but no effect on oocyte spontaneous maturation. CONCLUSION: Amphotericin B and ketoconazole are able to affect mouse oocyte maturation, and indicates that they have a regulation on FSH-induced synthesis of meiosis-activating sterol.

Amphotericin B↗
PubMed1999

Protein kinase C and intracellular calcium are involved in follicle-stimulating hormone-mediated meiotic resumption of cumulus cell-enclosed porcine oocytes in hypoxanthine-supplemented medium.

The present experiments were conducted to examine the hypothesis that follicle-stimulating hormone (FSH) can stimulate the hydrolysis of phosphoinositide, generating the intracellular second messengers to activate protein kinase C and mobilizing intracellular calcium, thus inducing oocyte meiotic resumption. Pig cumulus cell-enclosed oocytes (CEO) were cultured for 24 hr in 4 mM hypoxanthine (HX)-supplemented medium and treated with different agents in the following designs: (1) CEO were treated with neomycin (an inhibitor of phosphoinositide hydrolysis) in the presence of FSH or only treated with 7,12-dimethylbenzin(a) anthracene (DMBA, a tumor promoter which can cause phosphorylation of phospholipase C (PLC), formation of inositol triphophate, and mobilization of intracellular calcium) to mimic the direct activation of PLC; (2) CEO were challenged by FSH, together with sphingosine or staurosporine (two kinds of PKC inhibitors); or treated with phorbol myristate acetate (PMA, an activator of PKC) separately; (3) CEO were primed with BAPTA/AM (an intracellular calcium chelator) or BAPTA/AM +FSH for 60 min, and then transferred into a new culture medium supplemented with FSH but without BAPTA/AM; total culture time was 24 hr. At the end of the culture, the incidence of germinal vesicle breakdown (GVBD) was calculated. The results showed that: (1) FSH (100 U/liter) could stimulate pig CEO to override the arrest of HX and resume meiosis; DMBA (10(-8)-10(-5) M) itself also had such a kind of effect; whereas neomycin, at the level of 10-20 mM, could dramatically inhibit the stimulatory effect of FSH. (2) Staurosporine (10(-9)-10(-6) M) or sphingosine (10(-8)-10(-5) M) could also inhibit the effect of FSH in a dose-dependent manner on stimulating CEO to resume meiosis. However, PMA (10(-8)-10(-5) M) alone had a dual effect on the meiotic resumption of pig CEO. PMA, at the level of 10(-8)-10(-6) M, could stimulate CEO to resume meiosis, and at high concentration of 10(-5) M , it could even enhance the inhibitory effect of HX. (3) Priming CEO with BAPTA/AM only or BAPTA/AM +FSH for 60 min could significantly inhibit the effect of FSH in a dose-dependent manner. These results indicate that in the process of ligand-mediated meiotic resumption of pig CEO, FSH can stimulate the hydrolysis of phosphoinositide leading to the activation of PKC and mobilization of intracellular calcium; and suggest that multiple signaling pathways and signal interaction are involved in this process.

Animals↗
PubMed1998

Use of the appendix to replace the choledochus.

Ten cases of choledochal cyst (CC) were treated by biliary-appendicoduodenostomy. The follow-up comprised a patient interview, ultrasonography (US), and single-proton ejected computerized tomography (SPECT) scanning. In all cases an anti-reflux submucosal tunnel was added to the distal appendico-duodenostomy; all showed an uneventful postoperative course. All the dilated intrahepatic bile ducts had normalized on B-US postoperatively. Four children under went SPECT examination; all of them had patent neo-bile ducts. In the authors' opinion: (1) Anastomosing the cecal end of the appendix to the common hepatic duct seemed more favorable than the other way around, because the cecal end could be easily trimmed to the size of the common hepatic duct, which was more or less dilated in the presence of a CC; (2) It is necessary to add a submucosal tunnel to the distal appendicoduodenostomy to achieve a more reliable anti-reflux effect; and (3) Transposing the vascularized appendix through the retro-transverse colon simplified the procedure and might reduce the risk of retroperitoneal complications if bile leakage should occur.

Appendix↗
PubMed1994

[Introduction and cultivation of Cinnamomum cassia Presl].

Based on the study of biological characteristics, growth determination, quality examination, harvest and processing features, it has been proved that the introduction and cultivation of Cinnamomum cassial are feasible in such southern subtropics as the valleys along the Yangtze River in the southern part of Sichuan province. Specific cultivating techniques to adapt to the local climate are reviewed in the paper.

China↗