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C Zhai

Publications and source records attributed to C Zhai.

18 recordsLinked to original sources
PubMed2001

Increased platelet-derived growth factor (PDGF) release after laparotomy stimulates systemic tumor growth in mice.

BACKGROUND: Our laboratory has demonstrated that tumors grow larger and are more easily established following laparotomy than after carbon dioxide (CO2) pneumoperitoneum or anesthesia alone. We have also shown that tumor cells incubated with serum from laparotomized mice proliferated significantly faster in vitro than those incubated with plasma from mice that underwent laparoscopy or anesthesia alone. We hypothesized that differing levels of a plasma-soluble growth factor(s) postoperatively causes tumors to proliferate faster after laparotomy. This study's purpose was to isolate and characterize the plasma growth factor(s) responsible for the increased growth of systemic tumors after laparotomy. METHODS: Female Balb/C mice (n = 100) were randomized to two groups: anesthesia control (AC) or midline sham laparotomy (4 cm) (Open). Plasma was collected on Postoperative day 4. For the tumor proliferation assay, C-26 colon cancer cells were incubated in media with either 10% AC or Open "raw" plasma (not passed through column), or AC or Open plasma that had been passed through the column. For elution of heparin-binding proteins, plasma from each group was passed through a heparin-sepharose column. Elution of bound proteins was accomplished with a 0.1-2 M NaCl gradient. Each fraction was examined for protein content. For the anti-platelet-derived growth factor (PDGF) neutralizing antibody study, C-26 cells were incubated with one of four plasma preparations: AC or Open plasma alone, or AC or Open plasma incubated with anti-PDGF antibody. For both studies, tumor proliferation was determined after 2 days with an MTS/PMS assay. Results from each group were compared and differences determined using analysis of variance (ANOVA) and Tukey-Kramer tests. RESULTS: On heparin chromatography, a single elution peak consistent with PDGF was present in both AC and Open plasma and was 1.5 times greater in the Open plasma. The first tumor proliferation assay showed that tumor cells incubated with Open plasma proliferated 2.5 times faster than those with AC plasma (p < 0.0001). Passage of AC plasma through the column did not alter its mitogenic activity, but Open plasma thus treated demonstrated significantly decreased mitogenic activity. The second tumor proliferation assay showed that anti-PDGF antibody had no effect on the mitogenic activity of the AC plasma but decreased the mitogenic activity of the Open plasma to the AC plasma level. CONCLUSIONS: Laparotomy is associated with higher levels of a heparin-binding plasma factor, consistent with PDGF. The enhanced mitogenic activity of the OP plasma was neutralized with anti-PDGF antibody. Increased plasma levels of PDGF after laparotomy may be responsible for accelerated tumor growth following laparotomy in mice.

Adenocarcinoma↗
PubMed2001

[Efficacy of topical cyclosporine A on keratoplasty rejection in rats].

OBJECTIVE: To evaluate the efficacy of topical cyclosporine A (CsA) on a penetrating keratoplasty rejection model in rats. METHODS: Lou rats received orthotopic corneal allografts from inbred F344 donors. The rats were treated with one drop of topical solution four times daily for 30 days. Sixty rats were divided into one control (the matrix of CsA solution) and five treatment groups (0.5%, 1.0%, 2.0% CsA, glucocorticoid, glucocorticoid and 1.0% CsA). Rejection index (RI) and mean survival time (MST) were calculated, and histopathological and immunohistopathological examination were performed for each group. RESULTS: The graft MST was postponed by topical CsA treatment. There was significant difference between each treatment group and the control group (t greater-than-or-equal 2.28, P < 0.0l), especially 2% CsA, steroid and combined 1% CsA and steroid groups, the combined group being the most effective. The RI was lower in all the groups with topical CsA than that in the control group (P < 0.01). The effect of 2% CsA was the same as that of the steroid, while 1% CsA combined steroid was the most effective. The histopathological findings confirmed that the topical application of CsA reduced the inflammatory cells infiltrating the graft stroma and the neovascularization. Immunohistopathological analysis demonstrated that there were fewer CD(+)(11a) T cells and macrophages in the infiltration and intercellular adhesion molecule (ICAM)-1 positive cells in keratocytes and endothelium of grafts in the treatment groups than in the control group. CONCLUSIONS: Topical CsA can inhibit the keratoplasty rejection episodes in the rat and afford better results when combined with topical steroid.

Animals↗
PubMed2001

[An experimental study on subconjunctival interleukin-1 receptor antagonist for promotion of corneal transplant survival].

OBJECTIVE: To determine whether the subconjunctival application of interleukin-1 receptor antagonist (IL-1ra) can prolong the corneal graft survival in the rat model of orthotopic penetrating keratoplasty. METHODS: For all experiments, F344 corneas were transplanted into LOU (major histocompatibility-disparate) eyes. Experimental groups received subconjunctival injection of 50, 100 and 200 microg IL-1ra respectively, and the control group received the same volume of 0.9% normal saline instead for consecutive 2 weeks. All transplants were evaluated for 4 weeks after surgery for signs of rejection. RESULTS: The mean survival time (MST) of the grafts of the experimental groups was increased significantly (t = 0.00, P < 0.01) in comparison with the control group. The MST of the IL-1ra 200 microg group was increased significantly than that of the IL-1ra 50 microg group (t = 0.00, P < 0.01). Furthermore, the IL-1ra-treated grafts had significantly less corneal inflammation, infiltration, lower levels of opacity, edema, neovascularization and rejection index compared with the control group. CONCLUSIONS: Subconjunctival treatment of IL-1ra has a significantly positive effect on promoting corneal allograft survival. And its effect is dosage-dependent.

Animals↗
PubMed2000

[Study on nutrition composition and protein quality of a Chinese wild rice].

In order to exploit and develop the resource of a kind of Chinese wild rice[Zinania Lalifolia (Griseb) Turcz], the nutrition values of the Chinese wild rice from Luoma, Baoying, Hongze, Weishan and Tai lake were analyzed. The nutrients of Chinese wild rice per 100 g samples were protein 13.2 g, vitamin B1 0.59 mg, vitamin B2 0.07 mg, vitamin E 0.29 mg, zinc 1.60 mg, iron 2.69 mg, and they were higher than those of white rice. The amino acid score of Chinese wild rice was 84, the first limiting amino acid was threonine, and the protein efficiency ratio(PER) was 2.75. These data showed that the Chinese wild rice was a good food resource with higher nutrition value, therefore, the ancient and novel food resource might be used in Chinese diet as the North American wild rice that was used in American diet.

Oryza↗
PubMed1999

Delayed-type hypersensitivity response is better preserved in mice following insufflation than after laparotomy.

BACKGROUND: Our laboratory has previously used pig and rat models to demonstrate that delayed-type hypersensitivity (DTH) response to an antigen challenge is suppressed following laparotomy compared to insufflation. The purpose of this study was to develop a practical and reliable mouse DTH model that could be used in future studies to test immunomodulating drugs and therapies. METHODS: Female C3H/HeN mice (n = 100) were given three serial DTH challenges of 25 microl of 4 mg/ml phytohemagglutinin (PHA) 12 days before the test procedure, immediately following the test procedure, and on the 2nd postoperative day. All challenges were administered via subcutaneous injection in alternating footpads. The thickness of the footpad was determined with electronic calipers immediately prior to injection and 24 h following injection in a blinded fashion. The difference in thickness represents the response. On the day of the procedure, mice were randomized into the following three groups: (a) control (AC), (b) insufflation (INS), and (c) open (OPEN). AC mice underwent no procedure. INS mice underwent CO(2) insufflation at 2-4 mmHg for 20 min. OPEN mice underwent a midline incision from xiphoid to pubis that was closed after 20 min. Data were analyzed using ANOVA and Tukey-Kramer tests to determine differences between groups. RESULTS: Preoperatively, there were no significant differences among the three groups. On POD1, the OPEN group had significantly less response than both the AC and INS groups. On POD3, there were significant differences between the OPEN group and both the INS and AC groups. There was no significant difference between the AC and INS group at any time. CONCLUSIONS: In conclusion, a DTH mouse model has been established that allows serial assessment of cell-mediated immune function. This model can be used to study immune function after open and minimal access procedures in a simple and cost-effective manner.

Animals↗
PubMed1998

Tissue factor transcription driven by Egr-1 is a critical mechanism of murine pulmonary fibrin deposition in hypoxia.

Local hypoxemia and stasis trigger thrombosis. We have demonstrated previously that in a murine model of normobaric hypoxia pulmonary fibrin deposition is a result of expression of tissue factor, especially in oxygen-deprived mononuclear phagocytes (MPs). We now show that transcription factor early-growth-response gene product (Egr-1) is rapidly activated in hypoxia, both in vitro and in vivo, and is responsible for transcription and expression of tissue factor in hypoxic lung. MPs and HeLa cells subjected to hypoxia (pO2 approximately 13 torr) had increased levels of tissue factor transcripts (approximately 18-fold) and an increased rate of transcription (approximately 15-fold), based on nuclear run-on analysis. Gel-shift analysis of nuclear extracts from hypoxic MPs and HeLa cells demonstrated increased DNA-binding activity at the serum response region (SRR; -111/+14 bp) of the tissue factor promoter at Egr-1 motifs. Using 32P-labeled Egr consensus oligonucleotide, we observed induction of DNA-binding activity in nuclear extracts from hypoxic lung and HeLa cells because of activation of Egr-1, by means of supershift analysis. Transient transfection of HeLa cells with chimeric plasmids containing wild-type or mutant SRR from the tissue factor promoter showed that intact Sp1 sites are necessary for basal promoter activity, whereas the integrity of Egr-1 sites was required for hypoxia-enhanced expression. A central role for Egr-1 in hypoxia-mediated tissue factor expression was confirmed by experiments with homozygous Egr-1 null mice; wild-type mice subjected to oxygen deprivation expressed tissue factor and showed fibrin deposition, but hypoxic homozygous Egr-1 null mice displayed neither tissue factor nor fibrin. These data delineate a novel biology for hypoxia-induced fibrin deposition, in which oxygen deprivation-induced activation of Egr-1, resulting in expression of tissue factor, has an unexpected and central role.

Animals↗
PubMed1997

[p53 gene mutations in BALB/c 3T3 cells transformed by crocidolite].

This study sought to address the relationship between crocidolite and p53 gene mutation. The mutations of p53 gene in 8 BALB/c 3T3 cell lines transformed by crocidolite were analysed. Altogether 11 exons of the gene from 8 cell lines were detected by PCR-SSCP. 7 alterations were found; 2 of them were located in exon 4-6, and 5 in 9-11. Most of the mutations (5/7) were of one more band than that of wild cell from SSCP, and alterations were randomly scattered among the crocidolite doses groups. The results suggest that the presence of a p53 alteration is not related to the dose of crocidolite used. Besides, p53 mutation may occur in a relatively later period of the growth of the transformed cell lines. The results also showed that the mutations occurred predominantly in exons 9-11. This was different from that seen in human mesothelioma where mutations in the exon 5-8 of p53 gene were more frequently observed.

3T3 Cells↗
PubMed1996

Conformation of an analog of human follicular gonadotropin releasing peptide TF14 in solution by 2D-NMR.

Since the discovery of hF-GRP, several analogs have been synthesized in order to see their effects on the gonadotropin releasing activity, either as agonists or antagonists to this peptide. TF14 is one of these analogs, whose 14th position in the primary sequence is Phe instead of Asn in hF-GRP, while its activity is doubled. 2D-NMR (TOCSY, ROESY) was used to determine the conformation of TF14 in solution. Compared with hF-GRP, the whole peptide is in a non-typical more extended conformation, which may give some clue to the relation between structure and function of these two peptides.

Magnetic Resonance Spectroscopy↗
PubMed1995

[Cloning and sequencing of CTP synthetase cDNA from Chinese hamster cells].

The CTP synthetase cDNA was cloned from Chinese hamster lung cells V79. By comparison of the amino acid sequence of CTP synthetase with the counterpart of other species published, it was show that the CTP synthetase was a highly conserved and stable gene among the mammalian cells, but more differences of the CTP synthetase sequence could be seen between procaryotic and eukaryotic cells. This phenomenon suggested that the catalysing model of the enzyme might have some small differences in the organisms.

Animals↗
PubMed1992

[Mutagenesis study of ethylmethane sulfonate with shuttle vector plasmid pZ189].

Shuttle vector plasmid pZ189 was used as a molecular tool and the SupF inserted in the plasmid was worked as a target gene for mutagenesis study. The host cells (E. coli MBM 7070) with pZ189 were treated with ethylmethane sulfonate (EMS) and plated on the selective media containing X-gal (5-bromo-4-chloro-3-indolyl-beta-D-galactoside) and IPTG (isopropyl-beta-D-thiogalactoside). The SupF and the LacZ amber mutant carried by the host cells complemented each other and thus made the colonies blue on the selective media. However the colonies derived from the SupF mutants changed the colour from blue to white. The mutant frequencies in a series of experiments with different concentrations of EMS were estimated. Furthermore, the DNA isolated from 5 SupF mutants was digested with restruiction enzyme Hha I. It suggests that the 214 bp Hha I fragments containing mutant SupF could be distinguished from their wild type counterparts by temperature-gradient gel electrophoresis under optimal conditions.

Electrophoresis, Polyacrylamide Gel↗
PubMed1992

[Experimental study of use of shuttle vector to develop a system of detecting mutagenesis in mammalian cells].

UNLABELLED: The paper presents a series of experimental studies of the use of shuttle vector to develop a short-time mutagenesis system of detecting gene mutation in the mammalian cell at DNA level. The system is based on the finding that in the EB virus the shuttle vector pMCi5 carries LacI gene. The LacI is used as a target of induced mutagenesis in mouse cells. Use pMCi5 plasmid to transform the 3T3 mouse cell, expose it to a chemical mutagen, ethyl methanesulfonate (EMS); transfer the treated plasmid DNA to E. coli strain MC1061F' 150Kan; and then plate the transformation on a special culture medium containing X-gal for rapid detection and analysis of LacI mutation. RESULTS: The spontaneous mutant frequency of the system is less than 1.21 x 10(-4). After the treatment with 300 micrograms/ml EMS, the induced mutant frequency increases to 3.8 x 10(-3). No gross alteration has been discovered in seven LacI mutants at DNA level. No point mutation has occurred in the EcoRI site by analysis with restriction enzyme EcoRI.

3T3 Cells↗