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Biomedical subjects

C Zhang

Publications and source records attributed to C Zhang.

At least 433 records · Page 24Linked to original sources
PubMed1998

The role of the ran GTPase in nuclear assembly and DNA replication: characterisation of the effects of Ran mutants.

The Ran GTPase plays a critical role in nucleocytoplasmic transport and has been implicated in the maintenance of nuclear structure and cell cycle control. Here, we have investigated its role in nuclear assembly and DNA replication using recombinant wild-type and mutant Ran proteins added to a cell-free system of Xenopus egg extracts. RanQ69L and RanT24N prevent lamina assembly, PCNA accumulation and DNA replication. These effects may be due to the disruption of nucleocytoplasmic transport, since both mutants inhibit nuclear import of a protein carrying a nuclear localisation signal (NLS). RanQ69L, which is deficient in GTPase activity, sequesters importins in stable complexes that are unable to support the docking of NLS-proteins at the nuclear pore complex (NPC). RanT24N, in contrast to wild-type Ran-GDP, interacts only weakly with importin alpha and nucleoporins, and not at all with the import factor p10, consistent with its poor activity in nuclear import. However, RanT24N does interact stably with importin beta, Ran binding protein 1 and RCC1, an exchange factor for Ran. We show that Ran-GDP is essential for proper nuclear assembly and DNA replication, the requirement being primarily before the initiation of DNA replication. Ran-GDP therefore mediates the active transport of necessary factors or otherwise controls the onset of S-phase in this system.

Animals↗
PubMed1998

Murine enamelin: cDNA and derived protein sequences.

Enamelin is the largest enamel protein. Recently we reported the characterization of a cDNA clone encoding porcine enamelin. The secreted protein has 1104 amino acids--over 6 times the length of amelogenin (173 amino acids) and almost 3 times the lengths of sheathlin (395 amino acids) and tuftelin (389 amino acids). Immunohistochemistry has shown that uncleaved porcine enamelin concentrates at the growing tips of the enamel crystallites while its cleavage products localize to rod and interrod enamel. Here we report the isolation and characterization of cDNA encoding murine amelogenin and demonstrate the tooth specificity of porcine enamelin. The murine clone is 4154 nucleotides in length and encodes a protein of 1274 amino acids. In the absence of post-translational modifications murine enamelin has an isotope averaged molecular mass of 137 kDa and an isoelectric point of 9.4. Multiple tissue Northern blot analyses detect porcine enamelin mRNA in developing teeth but not in liver, heart, brain, spleen, skeletal muscle and lung. Mouse and porcine enamelin share 61% amino acid identity and 75% DNA sequence identity. Mouse enamelin has 14 tandemly arranged copies of an 11 amino acid segment that is found only once in porcine enamelin.

Amino Acid Sequence↗
PubMed1998

[Accumulative arsenic level in viscera in offsprings of exposed parent rats].

OBJECTIVE: To explore the metabolism and accumulation of arsenic in the offsprings of exposed rats. METHODS: Arsenic contents in viscera of the rat offsprings, whose parents exposed to different dose of arsenic, were determined with a two-generation reproductive test. RESULTS: Arsenic contents in the heart, liver, brain, kidney and spleen of the offsprings correlated with the dose their exposed parents, the highest in the spleen. There was significant difference in arsenic contents of the viscera between two generations of rats. Arsenic contents in the viscera of the offsprings declined significantly one month after stopping exposure to arsenic, but still higher than that in controls. CONCLUSION: It suggests that arsenic can deposit in the bodies of the rat offsprings, and excreted from the bodies slowly.

Animals↗
PubMed1998

Targeted diagnosis and treatment of superficial bladder cancer with monoclonal antibody BDI-1.

OBJECTIVE: To explore the application of monoclonal antibody (McAb) to targeted treatment of bladder carcinoma through a series of in vitro and in vivo studies carried out in animal model and patients with bladder carcinoma. METHODS: Monoclonal antibody BDI-1 against bladder carcinoma was prepared by the lymphocyte hybridoma technique. McAb was conjugated with 99mTc by direct reduction method. Momodin (MD) was covalently linked to McAb by SPDP method. Radioimmunoimaging of nude mice xenografts and patients with bladder carcinoma were performed with BDI-1-99mTc conjugates. An immunotoxin (BDI-1-MD) was inducted via a catheter into the bladder. Targeted treatment with BDI-1-MD was carried out in 18 patients. RESULTS: This study showed the specificity of McAb, and clear imaging of nude mice bearing xenografts. Distribution analysis of 99mTc-BDI-1 in nude mice showed the highest value of T/NT in bladder tumor. Targeted diagnosis and treatment for patients by intravesical administration are very safe and effective. CONCLUSION: The bladder cancer seems an ideal model for diagnostic and therapeutic approaches using regional administration of McAb conjugates via a catheter direct into the bladder.

Animals↗
PubMed1998

[The effect of blocking insulin-like growth factor-1 (IGF-1)-receptor system on tendon cell proliferation].

The purpose of this study was to find some solutions to the problem of tendon cell proliferation control. Under the condition of in vitro culture, several materials including IGF-1 receptor antibody and mRNA antisense oligonucleotide were added to the culture medium to block the IGF-1-Receptor system. The effect of the material on the tendon cell proliferation was judged by cell count after incubation of 48 hours. The results showed that both IGF-1 Receptor antibody (IGF-1R alpha) and IGF-1 Receptor mRNA antisense oligonucleotide had negative effect on tendon cell proliferation (P < 0.01 and P < 0.05). These findings lead us to think that the above two materials could be used in the experiment of tendon adhesion preventing and living ready-made tendon producing.

Cell Count↗
PubMed1998

[Experimental study of fibrin glue adhesion with epineurial anchor suture to repair peripheral nerves].

To prove and improve the technique of fibrin glue adhesion repair peripheral nerve, 20 male rats were chosen. All the rats was randomly divided into two groups: Suture group (n = 10) and glue adhesion group (n = 10). Left sciatic nerves of the rats were cut with knife and repaired by suture or adhesion methods separately according to their groups. When adhesive method being used, the epineurial was fixed with a suture method similar to anchor suture for preventing suture line broken. Immediatly after the repair and 8 weeks after the surgery, the histologic and electrophysiologic changes of the repaired nerve were observed. The result showed: The axonal copation was soon improved in glue adhesion group. At the eighth week, nerve fiber alignment of the adhesion group was more regular than that of the suture group. Moreover, there were great improvement of axon cross rate and the recovery rate of sectional area of nerve fiber at the distal end in glue adhesion group (P < 0.05, P < 0.01). It was concluded that glue adhesion was prior to suture in repair of peripheral nerve, and anchor suture could improve the technique of glue adhesion method.

Animals↗
PubMed1998

[The risk of lung cancer and mesothelioma in farmers exposed to crocidolite in environment].

To assess the risk of lung cancer and mesothelioma after environmental exposure to crocidolite for 20-30 years, a retrospective cohort study was carried out in farmers who had been exposed to crocidolite in environment. 1610 subjects were followed up for 9 years (Jan. 1, 1987 Dec. 31, 1995). The control group consisted of 7646 farmers who resided in the noncrocidolite pollution rural area in the same province. The results showed that the annual mortality rate was 43.75 per 100,000 population for lung cancer, and 36.46 per 100,000 for mesothelioma. Significantly high risks of lung cancer (RR 5.67) and mesothelioma (RR 182.3) were noted. These results demonstrate a strong causal association between lung cancer, mesothelioma and exposure to crocidolite.

Adult↗
PubMed1998

[Cytokines release related to cardiopulmonary bypass in patients with prosthetic valve replacement].

To examine cytokines release related to cardiopulmonary bypass(CPB), the anthers investigated the possible differences in cytokines responses between patients undergoing prosthetic valve replacement (study group, n = 10) and those receiving closure of patent ductus arteriosus or pericardiectomy(control group, n = 9). Venous levels of interleukin-2 (IL-2), soluble interleukin-2 receptor (sIL-2R), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), and interleukin-10 (IL-10) were measured at multiple time points before, during and after operation. As compared with pre-operative values, IL-2 levels in both groups decreased significantly (P < 0.05), and the levels of sIL-2R, IL-6, TNF-alpha, and IL-10 in both groups increased significantly at multiple time points post-operative (P < 0.01). All the values of cytokines returned to pre-operative levels at 7th post-operative day. Although there were no pre-operative differences in these cytokines between the two groups (P > 0.05), the post-operative changes of cytokines in study group was more obvious than that in control group (P < 0.01). In study group IL-10 rose to a peak value of around 620 pg/ml at the end of CPB while IL-6 and TNF-alpha levels reached their peak values of around 88 pg/ml and 52 pg/ml respectively at 1st post-operative day. IL-10 has been reported as an antiinflammatory cytokine. The preceding IL-10 peak value, as compared with the peak values of IL-6 and TNF-alpha, could be associated with the interplay and regulation of cytokine network. On the other hand, in control group the levels of IL-6, TNF-alpha, and IL-10 reached their peak values at 1st post-operative day simultaneously. The values were 34 pg/ml, 36 pg/ml, and 162 pg/ml respectively. This result suggests that besides surgical stress mediated cytokines production or suppression, CPB itself also results in obvious changes of cytokine metabolism. However further studies are needed to elucidate the underlying mechanisms and clinical value of post-operative cytokines production or suppression related to CPB in patients with prosthetic valve replacement.

Adult↗
PubMed1998

Effects of Huangdan capsule on plasma cGMP and ANP in rats with chronic renal failure.

The model of chronic renal failure (CRF) was made in 5/6 nephrectomized rats and Huangdan capsule was used to treat these rats. The levels of cyclic guanosine monophosphate (cGMP) and atrial natriuretic peptide (ANP) in plasma were examined. The results showed that Huangdan capsule could postpone the increase in the levels of cGMP and ANP, suggesting that by regulating the water and sodium metabolism, Huangdan capsule could ameliorate the glomerular filtration rate, and that Huangdan capsule could lower the levels of cGMP and ANP in plasma via body regulation.

Animals↗
PubMed1998

[The effect of recombinant tissue inhibitor of metalloproteinase-3 (TIMP-3) on tumor growth and metastases].

OBJECTIVE: To investigate the anti-cancer effect of tissue inhibitor of metalloproteinase-3 (TIMP-3) and its mechanism of action. METHODS: Recombinant TIMP-3(rTIMP-3) was prepared and used to study its effect on tumor growth and metastases in mice, and its effect on angiogenesis in chicken embryo allantoic membrane (CAM). RESULTS: rTIMP-3 was able to inhibit growth of subcutaneously implanted S180 sarcoma and hepatic carcinoma H22 in a dose-dependent manner. When the rTIMP-3 was given i.p. at a daily dose of 20 mg/kg body weight for 10 days, the growth of S180 sarcoma and H22 carcinoma was inhibited by 63.2% and 73.4%, respectively. The metastases of i.v. injected Lewis lung carcinoma(3LLC) was also suppressed by rTIMP-3, with an inhibition rate of 59.8%. rTIMP-3 was found to significantly inhibit angiogenesis in CAM assay. CONCLUSION: rTIMP-3 has anti-cancer activity, and the mechanism of action might be associated with its inhibition on extracellular matrix degradation and anti-angiogenesis.

Animals↗
PubMed1998

[Early postoperative intraperitoneal perfusion chemotherapy for advanced colorectal cancer].

OBJECTIVE: To study the effect of early postoperative intraperitoneal perfusion chemotherapy (IPPC) on the prevention of peritoneal recurrence and liver metastasis in patients with advanced colorectal cancer. METHODS: From 1990 through 1997, 102 patients with advanced colorectal cancer were admitted. The tumor invaded the intestinal serosa with elevated CEA in the peritoneal fluid. Fifty-four of the 102 patients, beginning from the operation day, were given IPPC, once per day for 6 days, with warm(43-45 degrees C) sterile double distilled water containing 1 g 5-Fu and 10 mg MMC. The other 48 patients, as control, received 1 g 5-Fu and 8 mg MMC by i.v. infusion, once per day for 6 days. In addition, oral tegafur was given to all patients with a total dose of 40 g. RESULTS: In patients treated with IPPC, peritoneal recurrence developed in 2 patients, liver metastasis in 2 patients whereas 12 cases had peritoneal recurrence and 6 had liver metastasis in patients treated by i.v. infusion. No complication developed in any of the treated patients. CONCLUSION: IPPC is effective in preventing tumor recurrence in the peritoneal cavity and metastasis to the liver in patients with advanced colorectal cancer. The treatment procedure is simple and safe.

Adolescent↗
PubMed1998

[Esophageal carcinoma in part of population of Yangquan City].

OBJECTIVE: To evaluate the contribution of genetic factors to the occurrence of esophageal carcinoma (EC). METHODS: A genetic epidemiology survey of one-tenth of the whole population (130,000 people) was conducted in 6 towns of Yangquan City, Shanxi province in 1994. 228 high-risk (EC) families were matched with equal number of control families. RESULTS: The heritability of EC among first grade blood relatives was 52.6%, that among second grade blood relatives was 31.2%, and the summing up powered heritability was 49.2%. the segregation ratio was 18 +/- 3%, far less than 25%, suggesting a multi-gene effect. The distribution of EC in families did not fit well the binomial distribution, suggesting familial aggregation. The relative risk among male first grade blood relatives was 10.49, female was 7.69, in sum was 9.17. The attributive risks (AR) among first grade blood relatives were 62.13/100,000(male), 99.14/100,000(female) and 75.15/100,000(total). All of these figures were higher than the average (40.17/100,000). CONCLUSION: Genetic factors plays important roles in occurrence of EC in the Taihang mountain region.

Aged↗
PubMed1998

[Carcinosarcoma of the larynx (with a case report)].

Carcinosarcoma of the larynx is a rare disease. In this article one case is reported. Combined with references we also discuss pathologic characteristic, clinical manifestation, treatment and prognosis in the article.

Aged↗
PubMed1998

[Correlation between human papillomavirus type and grading of cervical intraepithelial neoplasia].

OBJECTIVE: To disclose the correlation between human papillomavirus (HPV) type and grade of cervical intraepithelial lesion (CIN). METHODS: PCR and in situ hybridization (ISH) techniques were used to detect the presence of HPV 6B/11, 16, 18 in 61 cases of CIN and 12 cases of cervical squamous cell carcinoma (SCC). RESULTS: PCR showed HPV 6, 11 distributing mainly in low-grade squamous intraepithelial lesion (LSIL, 61.9%) and partly in CINII (20%), but not in CINIII and SCC. The frequency of HPV 16, 18 increased corresponding to the increasing of CIN grading and up to 83.3% in SCC. ISH showed HPV 6b/11, 16, 18 DNA hybridization intranuclear signal were diffusely distributed in LSIL and granular in appearance in episomal HPV. Similar signal were also seen in CINII infected by HPV 6b/11 and partly by HPV 16, 18, anyhow, CINIII, SCC and partly CINII HPV 16, 18 DNA hybridization were nongranular in appearance. CONCLUSION: low-grade SIL associated with "low-risk" types of HPV 6, 11 belonged to productive infection. CINIII and SCC associated with "high-risk" types of HPV 16, 18 belonged to integrated infection, while CINII belonged to either productive or integrated infection.

Carcinoma, Squamous Cell↗