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Xiao Yang

Publications and source records attributed to Xiao Yang.

68 records · Page 4Linked to original sources
PubMed2003

[The effects of the Smad3-knockout on the hematopoiesis of mouse].

The effects of the Smad3- knockout on the hematopoiesis of mouse were investigated in this work. Five pairs of wild type and Smad3- null mice were studied. White blood cell(WBC), red blood cell(RBC) and platelet (PLT) counting of peripheral blood cells were performed with blood obtained from tails. And white blood cells were classified by their morphology. Bone marrow nucleated cells (BMNCs) were counted and classified. The CFU-GM, BFU-E, CFU-GEMM yields were measured in each pair of mice. CFU-S yield of each mouse was measured by injecting bone marrow cells into lethally irradiated 8-10 weeks old wild type female mice. And the pathomorphism of their bone marrows, spleens and livers were observed. As a result, WBC and PLT of Smad3- null mice were significantly higher than those in wild type mice. Smad3- null mice had much more proportion of granulocytes in classification. There wasn't any difference in RBC counting and BFU-E measurement. The yield of CFU-GM increased, while the yields of CFU-GEMM and CFU-S markedly reduced. Bone marrows are actively proliferative, with granulocytosis. The granulocyte/erythrocyte ratio increased. There were no obviously alterative in spleen and liver. Thus Smad3- knockout results in a decreased number of stem and progenitor cells. Moreover hematopoietic differentiation is abnormal with a tendency to forming more granulocytes and platelets. The effect of Smad3 on hematopoiesis is correlative to that of TGF-beta.

Animals↗
PubMed2002

Sharp signature of a dx2-y2 quantum critical point in the Hall coefficient of cuprate superconductors.

We study the behavior of the Hall coefficient, R(H), in a system exhibiting dx(2)(-y(2)) density-wave order in a regime in which the carrier concentration, x, is tuned to approach a quantum critical point at which the order is destroyed. At the mean-field level, we find that n(Hall)=1/R(H) evinces a sharp signature of the transition. There is a kink in n(Hall) at the critical value of the carrier concentration, x(c); as the critical point is approached from the ordered side, the slope of n(Hall) diverges. Hall transport experiments in the cuprates, at high magnetic fields sufficient to destroy superconductivity, should reveal this effect.

Journal Article↗
PubMed2002

Disruption of Smad5 gene leads to enhanced proliferation of high-proliferative potential precursors during embryonic hematopoiesis.

SMAD proteins are downstream signal transducers of the transforming growth factor beta (TGF-beta) superfamily, which serve as pleiotropic regulators in embryonic and adult hematopoiesis. SMAD5, initially considered to mediate bone morphogenetic proteins (BMPs) signals, can also transduce the inhibitory signal of TGF-beta1 on proliferation of hematopoietic progenitors derived from human bone marrow. To define its specific role in regulation of primitive multipotential progenitors during early embryonic hematopoiesis, we examined Smad5(-/-) yolk sacs at E9.0 to 9.5 and detected an elevated number of high-proliferative potential colony-forming cells (HPP-CFCs) with enhanced replating potential. To exclude the possible influence of microenvironmental deficit on embryonic hematopoiesis in vivo, we performed in vitro embryonic stem (ES) cell differentiation assay and investigated the HPP-CFCs in particular. Smad5(-/-) embryoid bodies (EBs) contained an elevated number of blast colony-forming cells (BL-CFCs), the in vitro equivalent of hemangioblast, in contrast to reduced proliferation of primitive erythroid precursors (Ery/Ps) within the mutant EBs. More importantly, profoundly increased frequency of HPP-CFCs, featured with a gene-dosage effect, was detected within day 6 Smad5(-/-) EBs compared with the wild type. In addition, Smad5(-/-) HPP-CFCs displayed enhanced self-renewal capacity and decreased sensitivity to TGF-beta1 inhibition, suggesting a critical role of Smad5 in TGF-beta1 regulation of embryonic HPP-CFCs. Consistently, reverse transcription-polymerase chain reaction analysis detected alterations of the transcription factors including GATA-2 and AML1 as well as cytokine receptors in Smad5(-/-) HPP-CFC colonies. Together, these data define an important function of SMAD5 in negative regulation of high-proliferative potential precursors during embryonic hematopoiesis.

Animals↗
PubMed2002

The effect of ligustrazine on peritoneal transport in peritoneal dialysis.

In order to investigate the effect of ligustrazine (Lig) i.p. on peritoneal permeability in peritoneal dialysis and its side effects, creatinine was given intravenously and continuously to maintain the high plasma creatinine level. All the rabbits were divided into three groups: normal control group (group A), group B treated with 0.12% Lig and group C treated with 0.24% Lig. The peritoneal dialysis of all rabbits lasted 2 h. The plasma and dialysate levels of glucose, protein and creatinine were observed immediate, 30 min, 60 min, 90 min, 120 min after dialysis. Creastinine dialysate/plasma ratio (D/P), protein D/P ratio, glucose D/Do at different time points after dialysis and creatinine mass transfer area coefficient (MTAC) at 120 min were calculated. The structures of peritoneum were observed under optical microscope and electron microscope after continuously intraperitoneal injection of Lig for 14 days. The results showed that the 90-min and 120-min creatinine D/P ratios in the group C were higher than in the group A. The 120-min creatinine MATC in the group C was higher than in the group A. The rabbits treated with Lig did not show significant structure changes of peritoneum and signs of peritoneal irritation. It was suggested that Lig could increase mass transfer ability of peritoneum without significant side effects.

Animals↗
PubMed2002

Developmental control of histone mRNA and dSLBP synthesis during Drosophila embryogenesis and the role of dSLBP in histone mRNA 3' end processing in vivo.

In metazoans, the 3' end of histone mRNA is not polyadenylated but instead ends with a stem-loop structure that is required for cell cycle-regulated expression. The sequence of the stem-loop in the Drosophila melanogaster histone H2b, H3, and H4 genes is identical to the consensus sequence of other metazoan histone mRNAs, but the sequence of the stem-loop in the D. melanogaster histone H2a and H1 genes is novel. dSLBP binds to these novel stem-loop sequences as well as the canonical stem-loop with similar affinity. Eggs derived from females containing a viable, hypomorphic mutation in dSLBP store greatly reduced amounts of all five histone mRNAs in the egg, indicating that dSLBP is required in the maternal germ line for production of each histone mRNA. Embryos deficient in zygotic dSLBP function accumulate poly(A)(+) versions of all five histone mRNAs as a result of usage of polyadenylation signals located 3' of the stem-loop in each histone gene. Since the 3' ends of adjacent histone genes are close together, these polyadenylation signals may ensure the termination of transcription in order to prevent read-through into the next gene, which could possibly disrupt transcription or produce antisense histone mRNA that might trigger RNA interference. During early wild-type embryogenesis, ubiquitous zygotic histone gene transcription is activated at the end of the syncytial nuclear cycles during S phase of cycle 14, silenced during the subsequent G(2) phase, and then reactivated near the end of that G(2) phase in the well-described mitotic domain pattern. There is little or no dSLBP protein provided maternally in wild-type embryos, and zygotic expression of dSLBP is immediately required to process newly made histone pre-mRNA.

Animals↗
PubMed2002

[Generation and characterization of chondrocyte specific Cre transgenic mice].

A chondrocyte specific transgenic construct (pcol2A1-Cre) containing the cartilage specific type II collagen A1 promoter, the Cre recombinase gene and the polyA of human growth factor gene was generated. The 9.3 kb DNA fragments were recovered from Not I digested fragments and microinjected into 323 fertilized eggs. The injected eggs were implanted into the oviduct of 14 female mice. In the 52 offsprings, there were 10 mice carring the transgene identified by PCR, and the efficiency was 19.2%. The col2A1-Cre transgenic mice were crossed with a conditional gene targeting mice to check the Cre mediated recombination in multiple tissues. The results of the PCR analysis suggested that the Cre recombinase was expressed only in cartilaginous tissue and could mediate the recombination between the LoxP sites in vivo. The result was further confirmed by Southern-blot.

Animals↗
PubMed2002

[The progress of expressing vector for mammary gland bioreactor].

The mammary gland bioreactor has great commercial value, but the examples for high level expression of foreign gene were so few that the most examples were not suitable for commercial program. The key resolution for improving the expression level of foreign gene is the construction of expression vector for mammary gland bioreactor. Nearly, many new ideas and new methods about the construction of expression vector were presented, the article summarized them.

Animals↗
PubMed2002

[Progresses in mouse chromosome engineering].

Mouse chromosome engineering, characterized by deletion and rearrangement of large fragment of chromosome, has been an important method for studying the function of mouse genome on a large scale. The latest progress in mouse chromosome engineering was introduced.

Animals↗
PubMed2002

A transgenic mouse that targets the expression of Cre recombinase in pancreatic tissue.

The transgenic mice that express Cre recombinase in a tissue specific manner is a powerful tool in generating the conditional gene knockout mice. The rat insulin promoter was cloned target the expression of Cre in pancreatic tissue. The Cre gene was modified by adding the nuclear localization signal and the sequence for initiation by eukaryotic ribosomes at 5' terminal of the Cre gene. Cre gene was linked to the intron of human growth factor gene. This construct was introduced into the mouse eggs using microinjection. Seven mice were identified as founders carrying the Cre gene by PCR. The results of RT-PCR showed that the transgenic mouse from one founder could transcribe the foreign gene in pancreas. The Southern blot analysis indicated that the Cre recombinase expressed in pancreas of the transgenic mouse was functional.

Animals↗
PubMed2002

[Analysis of the proteomic changes of the serum of the Smad3 targeted deficient mice].

We have studied the proteomic changes of the serum of the Smad3 targeted deficient mice using 2-DE and PMF approaches. 7 proteins expressed at different level in wild type mice and the Smad3 deficient mice were identified. These results would benefit the research on diagnosis and therapy of osteoarthritis and provided clues to studying the important function of Smad3 mediated TGF-beta signals during the skeletal development.

Animals↗
PubMed2002

[Effect of lupus recipe on IL-6 and IL-10 secretion of splenic cells in vitro in lupoid mice].

OBJECTIVE: To investigate the effect of Lupus Recipe (LR) on IL-6 and IL-10 secretion of splenic cells in vitro in lupoid model mice and on anti-dsDNA antibody. METHODS: Chronic graft-versus-host disease model was used in the experiment. The model mice were divided into four groups, the model group was un-treated and the other three groups treated with LR, prednisone and combined treatment (prednisone + LR) respectively. The serum level of ds-DNA antibody, the ConA induced splenic cell proliferation in mice's splenic cell culture as well as the IL-6, IL-10 level in the supernatant of culture were determined after treatment and compared with those of normal controls. RESULTS: (1) The splenic cell proliferative reaction in the model group splenic cells was obviously higher than that of the normal control (P < 0.05); but that in the three treated groups was different from the control insignificantly (P > 0.05); (2) The serum anti-dsDNA in the model group was higher than that in the normal control, 1.75 +/- 0.25 vs 1.20 +/- 0.21 (P < 0.01), while the difference in comparison of the treated groups with the normal control was insignificant, (P > 0.05); (3) Splenic cell IL-6 and IL-10 secretion in the model group induced by ConA was higher than those in the treated groups and the controls significantly (P < 0.05). CONCLUSION: LR reveals the effect of immunosuppressor, which could inhibit the activation of T- and B-cells, reduce the Th2 cytokine formation and auto-antibody production so as to treat lupus erythematosus effectively.

Animals↗
PubMed2002

[Murine beta-casein gene sequences direct a human tissue plasminogen activator variant expressed in the milk of transgenic mice].

To investigate the ability of our cloned murine beta-casein locus to direct the exogenous gene expression in the milk of transgenic mice, the human t-PA variant mammary gland expression vector under the control of murine beta-casein gene regulatory elements was constructed, in which the human t-PA variant signal-pro peptide sequence was replaced with murine beta-casein signal peptide sequence and the human t-PA variant mature peptide cDNA was inserted into the second exon of beta-casein gene. The fusion gene was microinjected in the fertilized mice eggs. A total of 285 embryos were microinjected and transferred into 13 surrogate mother mice. Twelve positive transgenic mice were identified through PCR and Southern blot analysis among 42 new born mice. Human t-PA variant was expressed in the milk of 7 transgenic mice, the highest expression level attained to 3.6593 micrograms/ml. The results demonstrated that the murine beta-casein gene regulatory elements can direct the human t-PA variant gene successfully express in the milk of transgenic mice. It lays great foundation for the research on the beta-casein knock-in mice mammary gland bioreactor model construction.

Animals↗
PubMed2000

Expression of Smad4 Gene in Pichia pastoris and Identification of the Protein.

Smad4 is a novel tumor suppressor gene which is mutated or deleted in about 50% of pancreatic carcinoma and 30% of colon cancer. SMAD4 was expressed in Pichia pastoris and was characterized. The molecular weight of the expression product was shown to be about 67 kD, and 13 amino acids in N terminal were determined and were identical with the putative sequence from Smad4 cDNA, and it was able to specifically react with the antibody against SMAD4.

Journal Article↗