Biomedical subjects

J Sun

Publications and source records attributed to J Sun.

At least 253 records · Page 14Linked to original sources

PubMed2000

Factors affecting hepatocyte viability and CYPIA1 activity during encapsulation.

Hepatocytes encapsulated in alginate-poly-1-lysine-alginate (APA) are used in transplantation studies and in bioartificial liver support systems. Loss of cell viability in the process of APA encapsulation is usually 20-30% while the effect on cytochrome CYP450 activity is rarely reported. This work investigates the negative influences on hepatocyte viability and CYPIA1 activity during APA encapsulation, and reports methods to alleviate these influences by incorporating certain reagents into the encapsulation solution. The results show that loss of hepatocyte viability and CYPIA1 activity was caused almost entirely by extracellular calcium toxicity rather than by mechanical damage (p < 0.05). Use of 10 mM instead of 100 mM calcium chloride (CaCl2) in the encapsulation process improved CYPIA1 activity (p < 0.05), but did not improve hepatocyte viability (p > 0.05) or result in satisfactory microcapsules. Hepatocyte viability was 25% higher (p < 0.05) in CaCl2 than in calcium lactate (CaLa) when the cells were gelled by contact with these calcium solutions at room temperature (RT). Hepatocyte viability showed little improvement by processing at 4 degrees C than at RT in CaCl2 (p > 0.05) but was 23% higher at 4 degrees C than at RT in CaLa (p < 0.05). Calcium used in the process of encapsulation caused cell necrosis rather than apoptosis. Addition of Dulbecco's modified Eagle's medium (containing 10% foetal bovine serum) or 20 mM fructose to the calcium solution did not improve cell survival. However, nifedipine at a final concentration of 25 mM modestly improved hepatocyte survival in solution containing 100 mM CaCl2 (p = 0.003). Glutathione and taurine in certain concentrations showed protective effects against loss of CYPIA1 activity (p < 0.05 and <0.01 respectively). In conclusion, to optimise the use of calcium during the process of encapsulation, CaCl2 is preferred to CaLa and inclusion of nifedipine, glutathione or taurine in 100 mM CaCl2 solution is recommended.

Alginates↗

PubMed2000

Identification and chromosomal location of a new tandemly repeated DNA in maize.

Two clones of a new family of tandemly repeated DNA sequences have been isolated from a maize random genomic DNA library. MR68 is 410 bp, representing a monomeric unit and MR77 is 1222 bp, containing three units. The copy number was estimated to be about 3000 per 1C maize genome. Its methylation pattern was also determined. Fluorescent in situ hybridization (FISH) indicates that the sequence is located on the subtelomeric region of the long arm of chromosomes 3 and 6, as well as on the satellite of chromosome 6.

Base Sequence↗

PubMed2000

Estrogen receptors: selective ligands, partners, and distinctive pharmacology.

The action of nuclear hormone receptors is tripartite, involving the receptor, its ligands, and its co-regulator proteins. The estrogen receptor (ER), a member of this superfamily, is a hormone-regulated transcription factor that mediates the effects of estrogens and anti-estrogens (e.g., tamoxifen) in breast cancer and other estrogen target cells. This chapter presents our recent work on several aspects of estrogen action and the function of the ER: 1) elucidation of ER structure-function relationships and development of ligands that are selective for one of the two ER subtypes, ERalpha or ERbeta; 2) identification of ER-selective co-regulators that potentiate the inhibitory effectiveness of anti-estrogens and dominant-negative ERs and modulate the activity of estrogens; 3) characterization of genes that are regulated by the anti-estrogen-ER versus the estrogen-ER complex; and 4) elucidation of the intriguing pharmacology of these ER complexes at different gene regulatory sites. These findings indicate that different residues of the ER hormone-binding domain are involved in the recognition of structurally distinct estrogens and anti-estrogens and highlight the exquisite precision of the regulation of ER activities by ligands, with small changes in ligand structure resulting in major changes in receptor character. Studies also explore the biology and distinct pharmacology mediated by ERalpha and ERbeta complexed with different ligands through different target genes. The upregulation of the anti-oxidant detoxifying phase II enzyme, quinone reductase, by the anti-estrogen-occupied ER, mediated via the electrophile response element in the QR gene, may contribute to the beneficial antioxidant effects of anti-estrogens in breast cancer and illustrates the activation of some genes by ER via non-estrogen response element sequences. The intriguing biology of estrogen in its diverse target cells is thus determined by the structure of the ligand, the ER subtype involved, the nature of the hormone-responsive gene promoter, and the character and balance of co-activators and co-repressors that modulate the cellular response to the ER-ligand complex. The continuing development of novel ligands and the study of how they function as selective agonists or antagonists through ERalpha or ERbeta should allow optimized tissue selectivity of these agents for hormone replacement therapy and treatment and prevention of breast cancer.

Amino Acid Sequence↗

PubMed2000

[Construction, expression and activity test of a reshaping single-chain antibody against human CD3].

Monoclonal antibody (McAb) against human CD3 can adjust human body's immune statement in various ways, so that its clinical potential is highly regarded. In order to overcome the immunogenecity related to the murine McAb, this research effort was focused on constructing a reshaping single-chain antibody(scFv) against human CD3 employing antibody engineering. First, the CDRs of the murine McAb against human CD3 OKT3 was transplanted into the light-chain framework regions (FRs) of human McAb LS1 and the heavy-chain FRs of human McAb Nd respectively, spatial conformation was predicted by computer analysis. Then some particular residues were replaced in FRs basing on the result of conformational prediction to draw out the amino acid sequences of the reshaped VL and VH. The genes were chemically synthesize and inserted into an expression vector pROH80 to construct the reshaping scFv. Inducing the expression of reshaping scFv, the products are mainly as inclusion bodies. The reshaping scFv was expressed in another vector pALM. The inclusion bodies were denatured and then renatured by gel filtration. The renatured products were purified by immobilized metal affinity chromatograph (IMAC). Finally, the antigen-binding activily of the reshaping scFv against human CD3 was testified by the Compelitire in hibilory fluorescenceactivated cell sorting (FACS). The competitive inhibition rate is 18%.

Amino Acid Sequence↗

PubMed2000

Retinoblastoma protein activation of interleukin 8 expression inhibits tumor cell survival in nude mice.

Loss of retinoblastoma protein (Rb) has been implicated in the formation of a variety of human malignancies. Restoration of Rb expression in the cell lines representing these tumors eliminates or significantly reduces tumorigenicity in nude mice, but the mechanism for this Rb effect is unknown. Results from this study indicated that Rb expression reduced tumor cell survival in nude mice by dramatically enhancing interleukin 8 (IL-8) secretion. IL-8 secreted by the Rb-transformed cells attracted neutrophils in vitro and tumor-infiltrating neutrophils in vivo, which is consistent with the Rb-mediated tumor regression being dependent on IL-8. The apparent, contradictory roles of IL-8 as a protumorigenic and antitumorigenic cytokine are discussed.

Animals↗

PubMed2000

[Cytocompatible evaluation for skin reproducing membrane of medical fibroin].

This study was intended to evaluate the cytocompatibility of skin reproducing membrane of medical fibroin. Cell growth rate test and hemolysis test were conducted to investigate the cytotoxicity and hemolysis reaction for skin reproducing membrane. The results showed there was no obvious cytotoxicity for this kind of membrance. The hemolysis rate was 1.15%. In conclusion, skin reproducing membrane is a material of good cytocompatibility.

Animals↗

PubMed2000

[Detection of Japanese encephalitis virus in samples of JE patients by RT-PCR].

OBJECTIVE: To set up and assess the feasibility of RT-PCR method for Japanese encephalitis virus (JEV) detection, and use this method to detect clinical specimens. METHODS: The sensitivity of this RT-PCR was measured by plaque formation test, and the specificity of primers was proved by detecting some other flaviviruses. This RT-PCR was also compared with PRHI. RESULTS: JEV RNA could be detected successfully from viral culturing supernatants and from mouse brain infected by JEV. Its sensitivity of detecting JEV RNA from viral culturing supernatants was 64 PFU. A total of 38 specimens (of which 25 were serum specimens, 13 CSF specimens) from 16 clinically susceptible JE patients were examined by RT-PCR and RPHI Summing up the detection results of RT-PCR and RPHI, 14 patients among the 16 susceptible patients were affirmed as Japanese encephalitis patients. This RT-PCR is specific to JEV. The sensitivity of joint use of RT-PCR and RPHI to detect JEV was 100%, higher than using RPHI alone, and was 7.7% higher than using RT-PCR only. RT-PCR is more suitable for epidemiological survey than virus isolation. CONCLUSIONS: This RT-PCR for JEV detection is highly specific and sensitive. Toxemia period of JE patient is very short, so grasping the time of blood specimen collection will affect virus detection rate.

Encephalitis Virus, Japanese↗

PubMed2000

[Pot experiment on effect of clipping at seedling stage on spring wheat].

Pot experiment on the compensatory effects of spring wheat(Triticum aestivum) at different clipping intensities (simulating herbivory) at seedling stage (three leaves) was conducted in semiarid region of Gansu Province. Under two conditions of 60% and 90% of field water-holding capacity, spring wheat growth was stimulated by clipping at seedling stage, resulting in overcompensation in biological and economic yields, and with more compensation for heavy clipping than light clipping. The overcompensation of the spring wheat was at the cost of more water consumption.

Plant Development↗

PubMed2000

Interventional treatment of huge hepatic cavernous hemangioma.

OBJECTIVE: To study the methods of interventional treatment of huge hepatic cavernous hemangioma (HCH). METHOD: A total of 14 patients with HCH were treated with lipiodol-ultrafluid (10-15 ml), bleomycin A (PYM 16-32 mg), and gelatin-sponge particles. RESULTS: DSA hepatic arteriography showed multiple vascular lakes in the early arterial phase, so-called "to hang the fruits on the branches", which persisted for a long time. CT scan showed a significant reduction in tumor size in 8 of the 14 patients after the treatment. CONCLUSION: Embolization with lipiodol-ultrafluid, PYM and gelatin sponge particles is one of the best methods for the treatment of HCH.

Adult↗

PubMed2000

[Recurrence, metastasis and complications of stage I and II endometrial neoplasms treated by different therapeutic modalities].

OBJECTIVE: To make an approach to the relationship between recurrence, metastasis and complication of stage I and II endometrial carcinoma treated by 4 different therapeutic modalities. METHODS: To compare the rates of recurrence, metastasis and complication in 4 treatment groups (surgery, full-dose preoperative intracavitary irradiation, non-full dose preoperative intracavitary irradiation and radiation alone). RESULTS: Recurrence and metastasis in surgery, full-dose preoperative intracavitary irradiation, non full-dose preoperative intracavitary and radiotherapy alone groups were 19.8%, 8.1%, 22.2% and 34.6%, respectively. The recurrent rates of vaginal stump were 6.2%, 1.6%, 11.1% and 11.5%, respectively. The rates of proctitis and cystitis in full dose preoperative intracavitary irradiation group were 3.2% and 3.2%, 2.8 and 0.0% in non-full dose preoperative intracavitay irradiation group, and 0.0% and 3.8% in radiotherapy alone group. CONCLUSIONS: The rates of recurrence and metastasis in full-dose preoperative intracavitary irradiation group were the lowest compared with other groups and incidence of complication was also low. This therapeutic method is the optimal choice for the treatment of endometrial carcinoma with stage I and II.

Endometrial Neoplasms↗

PubMed2000

[Growth inhibition effect of 5-aza-CdR on endometrial carcinoma xenografted in nude mice by p16 gene demethylation].

OBJECTIVE: To study the antitumor effect and mechanism of 5-aza-CdR on endometrial carcinoma xenografted in nude mice. METHODS: The effects of 5-aza-CdR on tumor growth inhibition were observed on human endometrial carcinoma xenografted in nude mice. The methylation status of the 5' CpG island of the p16 gene was evaluated using methylation-sensitive restriction enzymes and polymerase chain reaction. p16 mRNA expression was determined by reverse transcription-polymerase chain reaction. RESULTS: The inhibition rates of the tumor were 79.10% in 5-aza-CdR group (P < 0.01), 90.32% in 5-aza-CdR + DDP group (P < 0.01), and 10.13% in DDP group (P > 0.05), respectively, in comparison with control group. The methylation level of p16 gene was gradually decreased and the p16 mRNA expression restored after exposure to 5-aza-CdR. CONCLUSION: Our data show that 5-aza-CdR may inhibit tumor growth by reactivating growth-regulatory gene silenced by de novo methylation.

Animals↗

PubMed2000

[Combination chemotherapy of uterine sarcomas].

OBJECTIVE: To study the results of combination chemotherapy of uterine sarcoma after operation and recurrent tumor. METHODS: One hundred seventy-four cases of three major pathological subtypes of uterine sarcomas were treated in the Cancer Hospital from 1960 to 1996. Clinical data were analyzed of 51 cases of uterine sarcomas treated with postoperative adjuvant chemotherapy and 38 cases with recurrent tumors received 98 courses of chemotherapy. They were divided into 4 groups according to the adjuvant chemotherapy regimen: single drug, VAC, VAD, and other regimens. Chemotherapy regimens for recurrent tumors were VAD, PA/PAC, and other combination regimens including etoposide, ifosfamide, cisplatin, adriamycin. RESULTS: The 5-year survival rate of stage I-II uterine sarcoma patients was 54.9% receiving adjuvant chemotherapy. It was 72.7% in VAD group which was significantly higher than that in other regimen groups. The survival rate was related to the number of chemotherapy course. The chemo-sensitivity of various pathological types of recurrent uterine sarcomas was not different. CONCLUSION: The 5-year survival rate does not improve in patients with stage I-II uterine sarcomas given postoperative chemotherapy. VAD is among the best regimens and at least 3 courses should be performed. The results of new treatment regimens such as EPA, IA, etc., must await further clinical observation.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

[Carcinoma of the vulva: a report of treatment].

OBJECTIVE: To analyse the outcome of various treatments for vulvar cancer and to investigate the characteristics of the recurrence and metastasis. METHODS: A total of 309 patients with carcinoma of vulva were analyzed retrospectively. RESULTS: The overall 5-year survival rate was 67.9%. That for stage I, II, III and IV was 86.9%, 82.5%, 59.2% and 43.6%, respectively. Treatment failure was seen in 49.8% of the treated cases, and it occurred within 2 years after primary treatment in the majority of the cases. Inguinal and pelvic recurrences, and distant metastases occurred within 2 years, while local recurreuce mostly after 2 years. Recurrence rate was not related to age of the patients. For stage I cancer, there was no difference in the results of different methods of treatment, but for stage II cancer, wide local resection plus inguinal lymphadenectomy was a better choice. In patients with regional lymph node metastases treated by nodal resection, it was less likely to recur than did radiotherapy. If no nodal involvement, the outcome of the two types of treatment was not different. Higher dose of radiation (Dm > or = 60 Gy) was better than lower dose (40-50 Gy) for prevention of recurrence. CONCLUSION: For early stage vulvar cancer, in addition to radical resection of vulva, preventive dissection of inguinal lymph nodes, or full dose radiation of the inguinal region, leads to better therapeutic results. For advanced cases, radical resection of the primary tumor with pre- and post-operative radiation, and inguinal lymph nodal disection, whenever possible, should be performed.

Female↗

PubMed2000

[Methylation and expression of the p16 gene in endometrial carcinoma].

OBJECTIVE: To analyse the relationship between methylation status of the 5' CpG island and mRNA expression of the p16 gene in endometrial carcinoma. METHODS: Methylation status of p16 gene was determined by methylation-sensitive restriction enzymes, PCR and p16 mRNA expression was evaluated by RT-PCR in a series of 8 specimens with normal endometrium(NE), 6 with simple and complex hyperplasia(SCH), 6 with atypical hyperplasia (AH) and 38 with endometrial carcinoma(EC). RESULTS: Eight specimens of NE displayed no methylation and showed normal expression of the p16 mRNA. In 1 of the 6 AH and 13 of the 38(34.21%) EC, there was methylation of p16 exon 1; 5 of the 6 SCH showed overexpression of p16 mRNA, 4 of the 6 AH and 27 of the 38 (71.05%) EC exhibited decrease or loss of p16 mRNA expression. CONCLUSION: Hypermethylation of p16 gene is an early event of endometrial carcinogenesis and is associated with the progression of endometrial carcinoma. Hypermethylation is highly correlated with inhibition of p16 gene transcription.

Cyclin-Dependent Kinase Inhibitor p16↗

PubMed2000

[Effect of Saikosaponin-d on up-regulating GR mRNA expression and inhibiting cell growth in human leukemia cells].

OBJECTIVE: To study the effect of Saikosaponin-d (SSd) on the expression of glucocorticoid receptor (GR) mRNA and cell growth in HL60 cells. METHODS: Antiproliferation effects of SSd on HL60 cells were determined by 3H-thymidine incorporation. Cell cycle analysis was also performed by flow cytometry. GRmRNA was analyzed by northern blot analysis. RESULTS: After 48 hours treatment with 10 micrograms/ml SSd, 3H-thymidine incorporation decreased in HL60 cells and the effect was time and dose dependent. The flow cytometry analysis showed HL60 cells were arrested at G0/G1 phase. The expression of GR mRNA increased. CONCLUSION: SSd exhibits the inhibition effects on cell growth in HL60 cells and could up-regulate the expression of GR mRNA in HL60 cells.

Anti-Inflammatory Agents↗

PubMed2000

[B domain mutations in the polymerase gene of hepatitis B virus during combination therapy with thymosin alpha1 and famciclovir in Chinese asymptomatic HBV carriers].

OBJECTIVE: To identify 'B domain' mutations of polymerase gene and its relationship with drug resistance during treatment with famciclovir in Chinese chronic asymptomatic HBV carriers. METHODS: Sequential sera from 29 Chinese chronic HBeAg positive HBV carriers treated with combination therapy with thymosin alpha1 (Talpha1) plus famciclovir and also from 15 cases treated with Talpha1 alone, were studied. Nucleotide sequences encoding 'B' and 'C domain' of the HBV polymerase gene were determined by direct or cloning sequencing methods. RESULTS: Nine Talpha1 plus FCV-treated and none of the Talpha1 treated patients developed mutations in the 'B domain' of polymerase gene which could result in amino acid changes. The development of 'B domain' mutations, during treatment, was significantly associated with HBV DNA rebound in those who received Talpha1 plus FCV. CONCLUSIONS: Mutations in FCV-treated patients resulting in amino acid changes mainly cluster in the 'B domain' of polymerase gene rather than in YMDD motif. The presence of mutations is significantly associated with HBV DNA rebound during treatment.

2-Aminopurine↗

PubMed2000

[Protective effect of nitric oxide on pancreas and its relation to sulfhydryl compounds and oxygen free radicals].

OBJECTIVE: To investigate the effect of endogenous nitric oxide (NO) on acute necrosis pancreatitis in rats and its relation to sulfhydryl compounds and lipid peroxidation. METHODS: Acute necrosis pancreatitis in rats was induced by retrograde sodium taurocholate (5%) infusion into the pancreatobiliary duct (1 ml/kg body weight), and N(G)-nitro-L-arginine (L-NNA) was used as the inhibitor of endogenous NO. The effect of endogenous NO on pancreatic injury, serum amylase level, the pancreatic tissue levels of sulfhydryl compounds, and malonaldehyde (MDA, the end product of lipid peroxidation) was evaluated, respectively. RESULTS: Sodium taurocholate administration induced evident pancreatic tissue edema and acinar necrosis, and intrapancreatic hemorrhage occurred in 2/7 rats. Both serum amylase and tissue MDA [(1.25 +/- 0.28) nmol/mg x pr vs. (0.5 +/- 0.03) nmol/mg x pr, P < 0.05] were significantly increased, but tissue sulfhydryl compounds were decreased markedly. Pretreatment with the NO inhibitor, L-NNA (12.5 mg/kg body weight), significantly intensified acinar necrosis and increased the intrapancreatic hemorrhage (10/12). L-NNA also resulted in a further increase of serum amylase and tissue MDA [(3.0 +/- 0.40) vs. (1.25 +/- 0.28) nmol/mg x pr, P < 0.05], but it had no effect on the tissue sulfhydryl compounds. CONCLUSION: Endogenous NO has the effect of pancreatic protection, and its antioxidation may be responsible, at least in part, for the protective mechanisms. Sulfhydryl compounds may not be involved in NO's pancreatic protection mechanisms.

Amylases↗

PubMed2000

[A dynamic study on the surgically induced astigmatism after phacoemulsification through three different-sized scleral tunnel incisions].

OBJECTIVE: To compare the changes in the values and directions of surgically induced astigmatism (SIA) after phacoemulsification with three different-sized scleral tunnel incisions and to evaluate their clinical results. METHODS: The patients were divided into three groups; the length of the scleral tunnel incision was 3.2, 5.5 and 7.0 mm respectively in A, B and C groups. Keratometry measurements were obtained preoperatively, at postoperative 1 week, 1 month and 6 months respectively. SIAs were analyzed by "Cravy vector method". The mean SIA and uncorrected visual acuity were compared among the groups up to 6 months postoperatively. RESULTS: Eyes in A group displayed significantly less mean SIA and better uncorrected visual acuity than B and C groups at 1 week postoperatively (P < 0.05), but there were no significant differences between any groups at 1 month, 3 months and 6 months postoperatively (P > 0.05). There were no significant differences in the mean SIA and uncorrected visual acuity between B and C groups throughout the whole study period (P > 0.05). CONCLUSIONS: SIAs in eyes of 3.2 mm incision group of phacoemulsification are less and more stable; a better and quicker rehabilitation of uncorrected visual acuity can be obtained in the early postoperative period.

Astigmatism↗