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Biomedical subjects

X Cao

Publications and source records attributed to X Cao.

At least 253 records · Page 14Linked to original sources
PubMed1996

Polymorphism of angiotensin I converting enzyme gene in the older Chinese: linked to ambulatory blood pressure levels and circadian blood pressure rhythm.

This study was undertaken to evaluate the association of polymorphism of angiotensin I converting enzyme (ACE) gene with causal and ambulatory blood pressure in the Chinese population. Genomic DNA was amplified by polymerase chain reaction (PCR) using primers flanking the polymorphic region in intron 16 of the ACE gene. Alleles were detected on agarose gels stained with ethidium bromide. Causal blood pressure was measured in the 133 normotensive and 122 essential hypertensive subjects; of the essential hypertensive subjects, 65 patients underwent non-invasive ambulatory blood pressure. There was no significant difference of ACE genotype and allele frequencies between the hypertensive and normotensive subjects. Non-significant differences were demonstrated in gender, age, causal blood pressure according to the ACE gene genotypes in the 65 patients who underwent non-invasive ambulatory blood pressure; however, effects of the ACE gene genotypes were observed on the derivatives of ambulatory blood pressure, including sleeping blood pressure levels and circadian blood pressure rhythm (p < 0.05). We suggest that insertion/deletion polymorphism of the ACE gene should be associated with blood pressure and ambulatory blood pressure might be superior to causal blood pressure at the molecular level.

Aged↗
PubMed1996

Casein kinase II associates with Egr-1 and acts as a negative modulator of its DNA binding and transcription activities in NIH 3T3 cells.

Although the activation domains within early growth response gene protein 1 (Egr-1) have been mapped, little is known of the kinases which phosphorylate Egr-1 and how phosphorylation correlates with the transcriptional activity of Egr-1. In this study we report that casein kinase II (CKII) co-immunoprecipitates with Egr-1 from NIH 3T3 cell lysates. The association of Egr-1 and CKII requires the C terminus of Egr-1 and CKII phosphorylates Egr-1 in vitro. The in vitro phosphorylation of Egr-1 by CKII and that induced by serum in vivo was compared by examining the CNBr-digested fragments of the phosphorylated Egr-1. CKII strongly phosphorylates fragments 7 and 10 which cover part of the activation/nuclear localization and DNA binding domains of Egr-1. CKII also phosphorylates, albeit weakly, fragments 5 and 8 which cover part of activation domain and the entire repression domain of Egr-1, respectively. Strong phosphorylation on fragment 10 as well as fragment 5 was also observed in Egr-1 immunoprecipitated from serum-induced, 32P-labeled cells. CKII phosphorylation of Egr-1 resulted in a decrease of its DNA binding as well as its transcriptional activities.

3T3 Cells↗
PubMed1996

Phorbol myristate acetate transactivates the avian beta 3 integrin gene and induces alpha v beta 3 integrin expression.

1,25-Dihydroxyvitamin D3 (1,25(OH)2D3)transactivates the avian beta 3 integrin gene whose promoter contains at least two vitamin D response elements, one of which is in close proximity to a candidate AP1 site (TGACTCA). Since fos/jun and steroid hormones interact to regulate gene expression, we asked whether phorbol-12-myristate-13-acetate (PMA), which stimulates binding of fos/jun to AP1 sites, transactivates the avian beta 3 integrin gene and, if so, does the phorbol ester modulate 1,25(OH)2D3 induction of the gene. We find the candidate AP1 sequence comigrates with the consensus AP1 sequence on electromobility shift assay when incubated with recombinant c-jun protein. Furthermore, PMA prompts expression of beta 3 integrin mRNA in the avian monocytic line, HD11. The increase in message reflects transactivation of the beta 3 gene and is mirrored by plasma membrane appearance of the integrin heterodimer alpha v beta 3. Moreover, attesting to the functional significance of PMA-enhanced alpha v beta 3 expression, cells treated with concentrations of the phorbol ester that induce the beta 3 gene, spread extensively on plastic, an event blocked by an anti-alpha v antibody and a peptide mimetic known to inhibit alpha v beta 3-mediated cell attachment. Interestingly, co-addition of 1,25(OH)2D3 and PMA prompts greater expression of alpha v beta 3 than when the cells are exposed to either agent alone and PMA enhances 1,25(OH)2D3-induced beta 3 integrin mRNA expression. Thus, PMA and 1,25(OH)2D3 impact on the avian beta 3 integrin gene independently and in combination.

Animals↗
PubMed1996

Identification of p90, a prominent tyrosine-phosphorylated protein in fibroblast growth factor-stimulated cells, as 80K-H.

Tyrosine phosphorylation of cellular proteins occurs rapidly upon treatment of fibroblasts with acidic or basic fibroblast growth factors (aFGF, bFGF), suggesting a role for protein phosphorylation in the FGF signaling pathway. Stimulation of Swiss 3T3 cells and MRC-5 fibroblasts with bFGF results in the tyrosine phosphorylation of several proteins, of which the most prominent has been designated as p90. The phosphorylation of p90 is observed within 30 s of treating the cells with FGF but not with other growth factors. Microsequencing of p90 resolved on two-dimensional polyacrylamide gel electrophoresis indicated an N-terminal amino acid sequence which corresponded to a protein previously named as 80K-H. Polyclonal antibodies raised against the predicted C terminus of 80K-H recognized p90 on all Western blots. p90 was found to bind specifically to GRB-2-glutathione S-transferase fusion protein and to be immunoreactive with 80K-H antibody. In addition, anti-phosphotyrosine antibodies immunoprecipitated 80K-H from cell lysates of FGF-stimulated but not from control fibroblasts. The biological function of 80K-H is yet unknown. However, from this study and a previous observation of the obligatory dependence of p90 phosphorylation on FGF receptor occupation, it appears that 80K-H is involved in FGF signaling.

3T3 Cells↗
PubMed1996

Transport of anti-sperm monoclonal IgA and IgG into murine male and female genital tracts from blood. Effect of sex hormones.

Ab levels in the genital tract may be important in fertility and in preventing sexually transmitted diseases. In this study, 125I-labeled polymer or monomer mAb IgA (C4pIgA or C4mIgA) and IgG2b (C4IgG) to murine lactate dehydrogenase C4 and a polymer mAb IgA (nplgA) not cross-reacting with mouse sperm were intravenously injected into BALB/c mice, and the relative distribution of these Abs was determined. Polymer IgA was transported much more efficiently into the genital tract, trachea, and duodenum of both sexes than C4IgG and C4 mIgA (p < 0.01). The transport of polymer IgA (C4pIgA and npIgA) into the male genital tract greatly increased following orchiectomy (p < 0.01); this change was not affected by testosterone, suggesting that the unknown regulatory factor(s) from the testis may suppress polymer IgA transport. However, the transport of polymer IgA into female genital tissues was significantly decreased by ovariectomy (p < 0.01); this decline can be rectified by beta-estradiol but not progesterone treatment, suggesting that estradiol may stimulate polymer IgA transport. Furthermore, the transport of C4IgG into tissues of the Fallopian tubes and the uterus was significantly decreased by treatment with progesterone (p < 0.01). Together, these findings indicate that serum polymer IgA can be transported selectively into the genital tracts of both sexes, that this transport is strongly under the control of gonads, and that transport of IgG into the Fallopian tubes and uterus is down-regulated by progesterone.

Animals↗
PubMed1996

Genetic variation of the poliovirus genome with two VPg coding units.

Amongst the picornaviruses, poliovirus encodes a single copy of the genome-linked protein, VPg wheras foot-and-mouth disease virus uniquely encodes three copies of VPg. We have previously shown that a genetically engineered poliovirus genome containing two tandemly arranged VPgs is quasi-infectious (qi) that, upon genome replication, inadvertently deleted one complete VPg sequence. Using two genetically marked viral genomes with two VPg sequences, we now provide evidence that this deletion occurs via homologous recombination. The mechanism was abrogated when the second VPg was engineered such that its nucleotide sequence differed from that of the first VPg sequence by 36%. Such genomes also expressed a qi phenotype, but progeny viruses resulted from (i) random deletions yielding single VPg coding sequences of varying length lacking the Q*G cleavage site between the VPgs and (ii) mutations in the AKVQ*G cleavage sites between the VPgs at either the P4, P1 or P1' position. These variants present a unique genetic system defining the cleavage signals recognized in 3Cpro-catalyzed proteolysis. We propose a recognition event in the cis cleavages of the polyprotein P2-P3 region, and we present a hypothesis why the poliovirus genome does not tolerate two tandemly arranged VPg sequences.

Amino Acid Sequence↗
PubMed1996

Avulsive amputations of the thumb: comparison of replantation techniques.

Twenty-five cases of avulsive amputation of the thumb are reported. Twenty-one of the 25 cases were categorized as Grade I avulsions (little or no skin defect) and four were categorized as Grade II avulsions complicated by a large skin defect. Three different replantation techniques were used and compared: (1) direct vessel anastomosis, (2) arterial anastomosis between the superficial branch of the radial artery and distal end of the thumb, and (3) arterial anastomosis after artery transfer from other digits. The authors concluded that direct vessel anastomosis was not the preferred method and that technique 2 could be used in any case but was especially suited to Grade II reconstructions. Technique 3 is mainly used in Grade I avulsions.

Amputation, Traumatic↗
PubMed1996

Active specific immunotherapy of pulmonary metastasis with vaccinia melanoma oncolysate prepared from granulocyte/macrophage-colony-stimulating-factor-gene-encoded vaccinia virus.

Vaccinia melanoma oncolysate (VMO) prepared with recombinant vaccinia virus encoding the gene of murine granulocyte/macrophage-colony-stimulating factor (GM-CSF) was tested for its therapeutic effect on melanoma pulmonary metastasis. The murine pulmonary metastasis model was established by injecting 2 x 10(5) B16F10 melanoma cells into the tail vein of a C57BL/6 mouse. Intraperitoneal injection of VMO was performed in tumor-bearing mice 3 and 10 days after B16F10 cell inoculation. The results showed that treatment with VMO prepared with GM-CSF-gene-encoded vaccinia virus (GM-CSFVMO) significantly decreased the number of murine pulmonary metastases and prolonged the survival of the tumor-bearing mice. Lymphocytes isolated from fresh blood and spleen of GM-CSFVMO-treated mice showed higher cytolytic activity against B16F10 melanoma cells when compared with lymphocytes from the mice of other treatment groups. Natural killer activity remained unchanged in the GM-CSFVMO-treated group. Cytotoxic activities of peritoneal macrophages were found to be greatly elevated in mice treated with GM-CSFVMO. Further study illustrated that the increased tumor necrosis factor and nitric oxide release from macrophages may contribute to their cytotoxic effects. These results suggest that the tumor oncolysate vaccine prepared with GM-CSF-gene-encoded vaccinia virus has a potent therapeutic effect on tumor metastasis through the efficient induction of antitumor immunity of the host, mainly through the cytotoxic effects of cytotoxic T lymphocytes and macrophages.

Animals↗
PubMed1996

Treatment of leukemia with fibroblast-mediated interferon-alpha gene therapy alone or in combination with doxorubicin.

The therapeutic effects of fibroblast-mediated human interferon-alpha (IFN-alpha) gene therapy, alone or in combination with Doxorubicin (Dox), a chemotherapeutic agent, on the human leukemia-bearing nude mice were investigated. An NIH3T3 fibroblast clone (NIH3T3-IFN-alpha +) secreting the highest level of human IFN-alpha was obtained from the human IFN-alpha gene-transfected fibroblasts. Three days after i.p. Implantation of NIH3T3-IFN-alpha + cells, a certain level of human IFN-alpha could be detected in the sera from the implanted mice. After the NIH3T3-IFN-alpha + cells were implanted intraperitoneally into leukemia-bearing nude mice, the growth of leukemia was inhibited and the survival time of the leukemia-bearing mice was prolonged. The growth of leukemia was inhibited more obviously and the survival rate of the mice increased significantly when NIH3T3-IFN-alpha + cells were implanted in combination with Dox. These results demonstrate that fibroblast-mediated human IFN-alpha gene therapy is effective in treating leukemia and may achieve a better therapeutic effect when combined with Dox.

3T3 Cells↗
PubMed1996

Activation and association of Stat3 with Src in v-Src-transformed cell lines.

STAT proteins are a group of latent cytoplasmic transcription factors which function as signal transducers and activators of transcription. Stat1 and -2 were originally identified to function in interferon signaling, and Stat1 was also found to be activated by epidermal growth factor (EGF) and other cytokines. New members of the STAT gene family are identified. Among them, Stat3 has 52.5% amino acid sequence homology with Stat1 and is activated by platelet-derived growth factor (PDGF), colony-stimulating factor 1 (CSF-1), EGF, interleukin-6, and other cytokines. Treatment of cells with EGF activates Stat1 and Stat3, which become phosphorylated on tyrosine residues to form homo - or heterodimers and translocate into the nucleus, binding to the sis-inducible element (SIE) in the c-fos promoter. Somatic cell genetic analyses demonstrated that Jaks, a family of nontransmembrane protein tyrosine kinases, are required for the activation of Stat1 and Stat2 in interferon-treated cells. However, little is known about the activation of Stat3 by growth factors. Here we report that in all v-Src-transformed cell lines examined, Stat3 is constitutively activated to bind to DNA and the phosphorylation of tyrosine on Stat3 is enhanced by the induction of v-Src expression. We also report that Src is shown to be associated with Stat3 in vivo, as well as in vitro, and phosphorylates Stat3 in vitro. Stat3 is also activated by CSF-1, possibly through CSF-1 receptor-c Src association in NIH 3T3 cells overexpressing CSF-1 receptors. Together, the data suggest that Src is involved in activation of Stat3 in growth factor signal transduction.

3T3 Cells↗
PubMed1996

Enhanced efficacy of combination of IL-2 gene and IL-6 gene-transfected tumor cells in the treatment of established metastatic tumors.

IL-2 and IL-6 are important cytokines which have potent antitumor effects and can cooperate to induce immune responses more effectively. IL-2 gene or IL-6 gene-transfected tumor cells exhibited reduced tumorigenicity and decreased metastatic potential. In order to increase the therapeutic efficacy of IL-2 gene-, IL-6 gene-modified tumor vaccines, the experimental pulmonary metastatic melanoma-bearing mice were treated with inactivated IL-2 gene-transfected tumor cells and inactivated IL-6 gene-transfected tumor cells. After the combined vaccination, the pulmonary metastases were reduced more significantly and the survival time of tumor-bearing mice was also markedly prolonged. The CTL activity, NK activity and IL-2-induced LAK activity, IL-2 and TNF secretion from the splenocytes of the above tumor-bearing mice increased more significantly than that of tumor-bearing mice vaccinated with IL-2 gene-transfected vaccine or IL-6 gene transfected vaccine alone. These results demonstrated that the combined use of IL-2 gene-transfected tumor vaccine and IL-6 gene-transfected tumor vaccine could achieve more potent antitumor effect via more effective activation of specific and non-specific antitumor immune responses.

Animals↗
PubMed1996

Construction of a brewing yeast having glucoamylase activity and its fermentation characteristics.

The brewing yeast having glucoamylase activity was constructed by integrating glucoamylase cDNA from Asapergillus niger into the genome of brewing yeast B48. The integration was achieved by cotransformation of YEP type plasmid pKG1 carrying glucoamylase expression-secretion element and was verified by Southern blot analysis. The engineered yeast was stable, and the fermentation test demonstrated that the lower residual dextrin level was obtained compared with control strain B48. Thus the fermentation rate was raised to 80.5%. No alteration of growth and brewing properties was observed. Beer quality was judged to be good.

Aspergillus niger↗
PubMed1996

[Experimental study on in vivo hematopoietic regulation of IL-6 gene-transfected tumor vaccine].

In the present study, we investigated the effects on hematopoiesis of inactivated vaccines prepared from mouse erythroid leukemia cells (FBL-3) transfected with IL-6 gene. After treatment with IL-6 gene-transfected FBL-3 cells, the platelet count in mice started to increase at day 4, reached its maximum at day 10 and lasted for 25 days. The neutrophil count also increased significantly, but WBC count remained unchanged. The CFU-GM and CFU-MK were elevated to some extent in bone marrow and spleen. These results indicated that in addition to augmentation of antitumor immunity, IL-6 gene-transfected tumor vaccine could promote hematopoietic functions in bone marrow and spleen, and elevate platelet and neutrophil counts in peripheral blood. This approach to gene therapy may be applicable in leukemia treatment, especially for thrombocytopenia related to leukemia or chemotherapy.

Animals↗
PubMed1996

[Acceleration of hematopoietic reconstitution in mice transplanted with syngeneic bone marrow cells by IL-6 gene therapy].

In the present study, the potential of fibroblast-mediated IL-6 gene therapy for accelerating hematopoietic reconstitution after syngeneic bone marrow transplantation (BMT) in BALB/c mice subjected to total body irradiation at a dose of 7 Gy was investigated. We observed that not only recovery of platelets, WBCs, CFU-GM or CFU-MK in bone marrow in mice treated with IL-6 gene therapy in combination with transplantation of 10(7) syngeneic bone marrow cells was faster than that in mice treated with IL-6 gene therapy in combination with transplantation of 10(6) or 10(5) syngeneic bone marrow cells, but also the number of CFU-S or survival rate in mice treated with IL-6 gene therapy in combination with transplantation of 10(7) syngeneic bone marrow cells was significantly higher. Nevertheless, the number of platelets, WBCs, CFU-GM or CFU-MK in bone marrow, CFU-S and survival rate in mice treated with IL-6 gene therapy in combination with transplantation of syngeneic bone marrow cells were elevated more significantly than that in mice transplanted with syngeneic bone marrow cells alone. These data demonstrated that IL-6 gene therapy could markedly augment hematopoietic reconstitution after syngeneic bone marrow transplantation and the more bone marrow cells transplanted, the better was the effect.

3T3 Cells↗
PubMed1996

[The in vitro antitumor responses of murine peritoneal macrophages induced by adenovirus-mediated IL-4 and/or M-CSF gene therapy].

OBJECTIVE: To observe the antitumor responses of murine peritoneal macrophages induced by adenovirus-mediated IL-4 and/or M-CSF gene transfer. METHODS: The IL-4 gene and/or M-CSF gene was transfected into murine peritoneal macrophages-mediated by adenovirus and the levels of IL-4, M-CSF, TNF, IL-1 and NO in the supernatant of the macrophages and the cytotoxicity of the macrophages to tumor cells were assayed. RESULTS: The high levels of IL-4 and M-CSF could be detected in the supernatant of macrophages 18 hours after being infected with advenovirus expressing IL-4 or M-CSF. The cytotoxicity of the macrophages engineered to secrete IL-4 or M-CSF increased significantly, and when IL-4 gene and M-CSF gene were cotransfected into the macrophages or the macrophages were co-stimulated with LPS, the cytotoxicity increased even more significantly. The levels of TNF, IL-land NO in the supernatant of macrophages also increased. CONCLUSION: The results demonstrated that transfection of IL-4 and/or M-CSF gene into macrophages could augment their anti-tumor immunity.

Adenoviruses, Human↗
PubMed1996

[Augmentation of liver immune functions by intrasplenic transplantation of IL-2 gene-modified hepatocytes].

OBJECTIVE: To investigate the effects of intrasplenically transplanted, IL-2 gene-modified hepatocytes on the liver immune response and anti-tumor activity. METHODS: Murine fetal hepatocytes BNL CL. 2 were transfected with mIL-2 gene in vitro, and intrasplenically transplanted into syngeneic mice (2 x 10(6)/mouse). After two weeks, the Kupffer cells were isolated and studied for cytotoxicity, TNF and NO production, and Ia expresson. The therapeutic effects on the mice with the metastatic liver carcinoma were also observed. RESULTS: The Kupffer's cytotoxicity to L1210, Yac-1, P815 and H22 target cells, and their production of TNF and NO were greatly augmented, even when freshly prepared. Their Ia expression also increased. When treated with IL-2 gene-modified hepatocytes, the metastatic liver carcinoma-bearing mice survived for a longer time. CONCLUSIONS: Intrasplenic transplantation of IL-2 gene-modified hepatocytes could effectively activate the liver immune response and exert potent therapeutic effects on liver carcinoma-bearing host.

Animals↗
PubMed1996

[An in vitro study on radiation-induced TNF gene therapy of cancer].

TNF has certain radioprotective effect on host tissues and can enhance the antitumor effect of radiotherapy. In addition, the promoter region of Egr-1 gene can be activated by radiation. So a radiation-inducible, double copy retroviral vector expressing TNF named pETDC was constructed by fusing of Egr-1 promoter to hTNF-alpha gene. After packaged with Psi-2 and Crip cells, the virus titer in the supermatant was 4 x 10(5) CFU/ml. By infection with the virus supermatant and by G418 resistant selection, positive clones from murine fibroblast cells NIH3T3 and murine melanoma cells B16.F10 were obtained and found to secrete 2.1 ng/ml and 1.1 ng/ml TNF respectively. After 20 Gy radiation of the cells, the TNF levels secreted by the two positive clones were elevated to 13.8 ng/ml (6.6-fold) and 5.7 ng/ml (5.2-fold). Furthermore, hTNF-alpha expression was confirmed with RT-PCR. These in vitro data provide an experimental basis for the in vivo use of combination TNF gene therapy with local radiotherapy in cancer patients.

3T3 Cells↗