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Biomedical subjects

Z Tang

Publications and source records attributed to Z Tang.

At least 127 records · Page 7Linked to original sources
PubMed1999

[Changes in trace elements in epithelial cells of oral submucous fibrosis].

OBJECTIVES: To assay the concentrations of the trace elements in intranuclei and extranuclei between oral submucous fibrosis (OSF) and normal buccal membrane, to observe the relationship between the trace elements and OSF, and finally to understand the mechanism of OSF. METHODS: The concentrations of the trace elements of internuclei and extranuclei in OSF epithelial cells were assayed in computer automatic process by electron probe micro-analysis. RESULTS: The concentrations of Cu, Zn, S, and As in OSF were significantly lower than those in the normal buccal membrane (P < 0.01). The concentrations of Se and Mo were significantly higher than those in the normal buccal membrane(P < 0.01). CONCLUSION: The epithelial cells of OSF are seriously damaged by the low level of Cu and Zn and high level of Se in intracell. These changes are the element bases that OSF has canceration trend.

Copper↗
PubMed1999

[Cytocompatibility of three substituted materials of human beings' hard tissue].

OBJECTIVE: To evaluate the osteocompatibility of three substituted materials of human beings' hard tissue (hydroxyapatite, bioglass ceramic and Ti-6Al-4V) and a new experimental method for evaluating the osteocompatibility of replaced materials of hard tissues in vitro. METHODS: The isolated osteoblasts from parietal and frontal bones of Sparague Dawley rats from 1 day to 3 days were used to estimate osteocompatibility of three substituted materials in vitro. The cells were inoculated onto specimens of HA, BGC and Ti-6Al-4V for 1 day, 3, 5 and 7 days, then the morphology and proliferating rates of cells on different materials were tested. RESULTS: Rat osteoblasts could attach, spread and proliferate on three materials as normal cells, and proliferating rates of cells on HA and BGC surface were as the same as normal, but that on Ti-6Al-4V was lower than the normal cells. CONCLUSION: The osteocompatibility of HA and BGC are better than that of Ti-6Al-4V and rat osteoblast culture system can be used to evaluate the osteocompatibility of substituted materials in vitro.

Alloys↗
PubMed1999

[Clinical therapeutic effects observation of iodophors on irrigation and disinfection of root canal].

OBJECTIVE: To evaluate clinical effects of iodophors on root canal therapy. METHODS: 147 teeth with root canal therapy collected from clinical patients were divided into two groups: experimental and control group. In experimental group, 0.05% and 0.5% iodophors were taken as irrigate agent and disinfectant, respectively, while in control group, 3% H2O2 + 0.9% NS and Fc were used. RESULTS: Clinical therapeutic effects evaluation indicated that there was no statistically significant difference of alteration of clinical syndromes after the administration and the therapeutic effect between experimental group and control group during the period of root canal therapy. CONCLUSION: Iodophors could be taken as a kind of candidate drugs on irrigation and disinfection of root canal therapy.

Adolescent↗
PubMed1999

[Influence of radiation on the blood-brain barrier and optimum time of chemotherapy].

OBJECTIVE: A pilot study of the destructive effects of radiation on the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BCSFB) were carried out on 29 patients. METHODS: (1) First BBB with localized and limited brain tumors was examined by 99mTc-GH imaging count/pixel, data was obtained from the unirradiated, irradiated, and tumor areas of before and after radiotherapy of 20-40 Gy respectively. (2) The BCSFB was studied quantitatively by observing the effect of methotrexate (MTX) permeation into the CSF before, during, and after brain irradiated after i.v. injection of MTX. RESULTS: (1) the BBB in the unirradiated area outside the radiation portal was not changed, (2) the degree of destructive effect on the BBB in the irradiated normal area and on the BCSFB were directly proportional to radiation doses. CONCLUSIONS: When the permeation of BBB and BCSFB irradiated, was enhanced the degree of destructive effect were enhanced proportionally with irradiation doses. It was that the BBB irradiated can be recovered at least partially after irradiation of 3 weeks proved. After a dose of 20 Gy irradiation, the BCSFB would gradually open. As compared with the pre-radiation data, the permeability of MTX increased by 1.05-1.3 times. So, it was advisable to give chemotherapy after 20 Gy irradiation.

Antimetabolites, Antineoplastic↗
PubMed1998

[Kinetic effect of testosterone or estradiol on iodine absorption in castrating rat intestine].

OBJECTIVE: To observe the effect of testosterone or estradiol on iodine absorption in rat intestine. METHOD: 50 male adult Wistar rats were divided into 5 groups randomly. 50 females were divided into another 5 groups. Among them, 4 groups were bilaterally testectomized or ovariectomized, 1 group was sham-operated. 7 days after operation, the castrated rats received testosterone (male rats) or estradiol (female rats) at different dosages by intramuscular injection for three days. Then the kinetics of iodine absorption in jejunum and ileum were observed by perfusion in situ. When finished, serum were obtained for detecting TSH, T4 and testosterone or estradiol. RESULTS: In castrated male rats, the value of K12 reduced, K21 increased, K02 reduced, and SP1/2 (the half time of the slow phase) prolonged, implying that the ability of iodine absorption reduced. It reflected that testosterone could promote iodine absorption in intestine in physiological condition. In castrated female rats, the situation was different from that in male rats, the value of K12 increased, K21 reduced, K02 increased, and SP1/2 shortened in jejunum, implying that the ability of iodine absorption increased. It reflected that estradiol could inhibit iodine absorption in intestine in physiological condition. The levels of serum TSH and T4 were not changed significantly in this experiment. CONCLUSION: In physiological condition, testosterone can promote iodine absorption, while estradiol has the inhibiting effect. The results indicate that gonadol hormone maybe one factor which can influence iodine absorption in intestine. It may explain the phenomenon that the incidence of goiter is different between males and females partly.

Animals↗
PubMed1998

GATA6 regulates HNF4 and is required for differentiation of visceral endoderm in the mouse embryo.

GATA6 belongs to a family of zinc finger transcription factors that play important roles in transducing nuclear events that regulate cellular differentiation and embryonic morphogenesis in vertebrate species. To examine the function of GATA6 during embryonic development, gene targeting was used to generate GATA6-deficient (GATA6(-/-)) ES cells and mice harboring a null mutation in GATA6. Differentiated embryoid bodies derived from GATA6(-/-) ES cells lack a covering layer of visceral endoderm and severely attenuate, or fail to express, genes encoding early and late endodermal markers, including HNF4, GATA4, alpha-fetoprotein (AFP), and HNF3beta. Homozygous GATA6(-/-) mice died between embryonic day (E) 6.5 and E7. 5 and exhibited a specific defect in endoderm differentiation including severely down-regulated expression of GATA4 and absence of HNF4 gene expression. Moreover, widespread programmed cell death was observed within the embryonic ectoderm of GATA6-deficient embryos, a finding also observed in HNF4-deficient embryos. Consistent with these data, forced expression of GATA6 activated the HNF4 promoter in nonendodermal cells. Finally, to examine the function of GATA6 during later embryonic development, GATA6(-/-)-C57BL/6 chimeric mice were generated. lacZ-tagged GATA6(-/-) ES cells contributed to all embryonic tissues with the exception of the endodermally derived bronchial epithelium. Taken together, these data suggest a model in which GATA6 lies upstream of HNF4 in a transcriptional cascade that regulates differentiation of the visceral endoderm. In addition, these data demonstrate that GATA6 is required for establishment of the endodermally derived bronchial epithelium.

3T3 Cells↗
PubMed1998

A histone deacetylase corepressor complex regulates the Notch signal transduction pathway.

The Delta-Notch signal transduction pathway has widespread roles in animal development in which it appears to control cell fate. CBF1/RBP-Jkappa, the mammalian homolog of Drosophila Suppressor of Hairless [Su(H)], switches from a transcriptional repressor to an activator upon Notch activation. The mechanism whereby Notch regulates this switch is not clear. In this report we show that prior to induction CBF1/RBP-Jkappa interacts with a corepressor complex containing SMRT (silencing mediator of retinoid and thyroid hormone receptors) and the histone deacetylase HDAC-1. This complex binds via the CBF1 repression domain, and mutants defective in repression fail to interact with the complex. Activation by Notch disrupts the formation of the repressor complex, thus establishing a molecular basis for the Notch switch. Finally, ESR-1, a Xenopus gene activated by Notch and X-Su(H), is induced in animal caps treated with TSA, an inhibitor of HDAC-1. The functional role for the SMRT/HDAC-1 complex in CBF1/RBP-Jkappa regulation reveals a novel genetic switch in which extracellular ligands control the status of critical nuclear cofactor complexes.

3T3 Cells↗
PubMed1998

[G6PD gene mutations in Guangxi, China].

OBJECTIVE: Fifty-six G6PD-deficient male individuals of the Guangxi origin were investigated at the molecular level to understand the basis of G6PD deficiency. METHODS: PCR amplified the exons 2,5,6,7,8, 10,11,12 and 13 of the G6PD gene respectively, combined with ASO dot blot hybridization and restriction enzymes digestion methods to screen 10 common Chinese G6PD mutations. RESULTS: Six mutations were detected, namely cDNA1376(G-->T)(25.0%), cDNA1388(G-->A)(16.1%), cDNA95(A-->G)(19.8%), cDNA592 (C-->T)(7.1%), cDNA1024(C-->T)(1.8%) and cDNA392(G-->T) (1.8%). The unknown mutations accounted for 28.6%. cDNA1311(C-->T),cDNA1360(C-->T),cDNA835(A-->T), cDNA493(A-->G) and cDNA487(G-->A) were not discovered among the cases. CONCLUSION: The findings may provide some useful informations for physician scientists to get insight into the pathogenesis of G6PD deficiency so as to improve clinical diagnosis, prevention and cure of G6PD deficiency. The results may be of significance in anthropology and geneties as well.

Glucosephosphate Dehydrogenase↗
PubMed1998

Fission yeast mitotic regulator Dsk1 is an SR protein-specific kinase.

Intricate interplay may exist between pre-mRNA splicing and the cell division cycle, and fission yeast Dsk1 appears to play a role in such a connection. Previous genetic analyses have implicated Dsk1 in the regulation of chromosome segregation at the metaphase/anaphase transition. Yet, its protein sequence suggests that Dsk1 may function as a kinase specific for SR proteins, a family of pre-mRNA splicing factors containing arginine-serine repeats. Using an in vitro system with purified components, we showed that Dsk1 phosphorylated human and yeast SR proteins with high specificity. The Dsk1-phosphorylated SF2/ASF protein was recognized strongly by a monoclonal antibody (mAb104) known to bind the in vivo phosphoepitope shared by SR proteins, indicating that the phosphorylation sites resided in the RS domain. Moreover, the fission yeast U2AF65 homolog, Prp2/Mis11 protein, was phosphorylated more efficiently by Dsk1 than by a human SR protein-specific kinase, SRPK1. Thus, these in vitro results suggest that Dsk1 is a fission yeast SR protein-specific kinase, and Prp2/Mis11 is likely an in vivo target for Dsk1. Together with previous genetic data, the studies support the notion that Dsk1 may play a role in coordinating pre-mRNA splicing and the cell division cycle.

Cell Cycle↗
PubMed1998

An externally powered, multichannel, implantable stimulator-telemeter for control of paralyzed muscle.

An implantable integrated stimulator and telemetry system has been developed. The system is capable of fulfilling the stimulus and telemetry needs of advanced functional neuromuscular stimulation (FNS) applications requiring multiple channels of stimulation and multiple channels of sensor or biopotential sensing. This system provides a command control structure, an inductive radio frequency link providing power to the implant device as well as two-way transcutaneous communication, an ASIC for decoding the command and for providing functional control within the implant, and modular circuitry providing the application specific implant functions. Biocompatible hermetic packaging, lead systems, and in-line connectors suitable for long-term implantation, provide encapsulation for the circuitry and access to the electrodes and sensors used in the application. The first implant configuration realized from this modular system is targeted for clinical implementation in persons with tetraplegia at the C6 level for restoration of hand function, using wrist position as the command control source. The implant device realized has ten channels of stimulation and telemetry used to control and sense a joint angle transducer implanted in the radio-carpal joint of the wrist. A prototype device has been fabricated and is undergoing testing in an animal.

Algorithms↗
PubMed1998

[Prevalence of peptic ulcer and its associated factors in elderly people in Beijing].

Survey on the prevalence rate of peptic ulcer (PU) and its associated factors in 3440 elderly people aged 60 or above, living in some area of Beijing is reported in the paper. The survey was carried out from July to October, 1993 through administration of household questionnaire. Result showed that the prevalence rate of PU was 4.1%, higher among males (5.3%) than in females (2.9%). There were more, younger, elderly and more farmers living in mountainous areas suffered from the disease than, older, elderly and rural farmers or urbanial residents. It is demonstrated that depression, intelle ctual work, cigarette smoking, heavy alcohol intake and higher educational level were correlated with the occurrence of the disease in the elderly. Neither dietary structure or light alcohol intake was found to be associated with prevalence of PU with statistical significance. We revealed that the prevalent rates of PU in the elderly were different according to age, sex, geographic area, educational level and professional aspects. The influence of psychological factors to the prevalence rate of PU should also be considered.

Aged↗
PubMed1998

Alterations of oncogenes, tumor suppressor genes and growth factors in hepatocellular carcinoma: with relation to tumor size and invasiveness.

OBJECTIVE: To make a better understanding of the molecular mechanisms involved in recurrence and metastasis of the hepatocellular carcinoma (HCC), some invasion related oncogenes, and growth factors have been investigated. METHODS: The studies were separately carried out, the results of which were summarized in this article with relation to tumor size and invasiveness of HCC. RESULTS: The aberration rates of p53 and CDKN2 in HCC were 45.9% and 36.4% respectively, which were higher in invasive HCC compared with non-invasive HCC. H-ras expression was positive in 29.3% of HCC, which was associated with recurrence and extrahepatic metastasis of HCC. Intralesional injection of H-ras antisense gene markedly inhibited the tumor growth and metastasis of HCC in nude mice. The positive rates of transforming growth factor (TGF)-alpha, epidermal growth factor receptor (EGFR) and c-erbB-2 were 45.7%, 47.1% and 92.3% respectively. The expression of EGFR was closely related to TGF-alpha, which was related to HCC recurrence. But no obvious difference of TGF-alpha or c-erbB-2 expression was found between HCC with and without recurrence, or with and without extrahepatic metastasis. Expression of nm23/tissue inhibitor of metalloproteinase (TIMP)-2 was positively associated with the prognosis of HCC patients (Log-rank, P < 0.001). The alterative rates of above-mentioned genes and growth factors in small HCC were slightly lower than that in large ones, but no significant difference was shown except the p53 mutation. CONCLUSIONS: The p53/CDKN2 mutation, over-expression of H-ras/EGFR, were associated with the invasiveness and recurrence of HCC. H-ras antisense gene might be of potential implication in the control of HCC recurrence and metastasis. Expression of nm23/TIMP-2 was closely related to the prognosis of HCC patients. Biological characteristics remained critical points to the prognosis even in small HCC.

Animals↗
PubMed1998

[Management of hepatic trauma in 267 cases].

Two hundred and sixty-seven consecutive hepatic trauma in recent 17 years were analysed. They were classified by AAST classification: grade I and II 68 cases (25.4%), grade III 132 cases (49.44%), grade IV 52 cases (19.48%) and grade V 15 cases (5.6%) and 237 cases were operated in different procedures according to the severity of the trauma. More than ten modalities such as dedridement, suturing, repairment, abdominal drainage, billiary drainage, hepatic artery ligation, packing and pressing hemostasis, resection of traumatic parecchyma, vessel ligation with suturing in section etc were used, The morbidity and mortality were 20.6% and 8.9%, respectively. The other 24 cases were found no active bleeding during laporatomy and rehabitated with preservative management. The authors believe that effective management on time and intensive perioperative care are important to minimize the morbidity and mortality of hepatic trauma. Nonoperative management deserves enough attention.

Adolescent↗
PubMed1998

[Establishment of a human hepatocellular carcinoma (HCC) cell line with high metastatic potential (MHCC97) and its biological characteristics].

OBJECTIVE: To establish and characterize a human hepatocellular carcinoma cell line with high metastatic potential derived from a subcutaneous xenograft of metastatic human HCC in nude mice (LCI-D20). METHODS: Single-cell suspension collected by tearing tumor tissues with forceps was transferred to the tissue culture flasks for culture in vitro in medium DMEM supplemented with 10% human group AB serum. Cytogenetic studies were performed on this cell line using flow cytometry and chromosome G-banding. AFP of theprimary xenografts and lung metastatic lesions was detected by using ABC immunohistochemistry. The rates of its tumorigenicity and metastasis in nude mice were evaluated. RESULTS: The MHCC97 cells showed typical epithelial appearance. Upon subcutaneous or intrahepatic inoculation in nude mice, the xenograft grew and metastasized to the lungs. The metastatic rate was 100%. The cancer cells of lung metastatic foci were AFP positive. Aberrant chromosomes i(1)(q) and der(4) (pter-->q35::?) were its chromosome markers. CONCLUSION: The MHCC97 cell line maintained the biologic characteristics as its original xenografts. The presence of the reported chromosomal aberrations may be related to carcinogenesis and progression of HCC.

Adult↗
PubMed1998

[Expression of vascular endothelial growth factor correlates with invasion and metastasis of hepatocellular carcinoma].

OBJECTIVE: To study the relationship between the expression of vascular endothelial growth factor (VEGF) mRNA and invasion and metastasis of hepatocellular carcinoma (HCC), and explore new approaches to prevent and inhibit recurrence and metastasis of HCC. METHODS: Surgical samples of 43 patients with HCC were studied using reverse transcription-polymerase chain reaction (RT-PCR). The relative level of VEGF mRNA expression was measured by determining a ratio of PCR products of VEGF to that of beta-actin gene. RESULTS: (1) Expression of VEGF mRNA expression in tumor tissue was found in 79.1% (34/43) of patients, whereas it was seen in 20.9% (9/43) of the nontumorous liver tissue. (2) The level of VEGF mRNA expression in tumors with tumor emboli or in non-encapsulated tumors was higher than that without tumor emboli or in well-encapsulated tumors (P < 0.05). (3) There was no significant difference in the expression of VEGF mRNA between large HCC (diameter > 5 cm) and small HCC (diameter < or = 5 cm) (P > 0.05). CONCLUSION: VEGF may play an important role in the invasion and metastasis of HCC. Angiogenesis in tumor correlates with the progression of HCC.

Adult↗
PubMed1998

[Urokinase-type plasminogen activator (uPA), uPA receptor (uPA-R) and inhibitors (PA I -1) expression in hepatocellular carcinoma in relation to cancer invasion/metastasis and prognosis].

OBJECTIVE: To study the relevance of uPA, uPA-R and PA I -1 to hepatocellular cancer (HCC). METHODS: The expression at protein level for uPA, uPA-R and PA I -1 was examined in 48 cases of HCC and 12 cases of benign tumors of the liver (as control) immunohistochemically. RESULTS: When compared to HCC-adjacent normal liver tissue and the control, positive rates of immune staining for uPA, uPA-R and PA I -1 on cell membrane were significantly higher in HCC cells (P < 0.05). Positive staining of uPA and uPA-R was seen in 16 of 22 and 19 of 22 cases of HCC with invasion, respectively (P < 0.01 and < 0.001). In 8 of 8 cases with cancer emboli, and in 6 of 6 cases with lymph node metastasis was the expression of uPA-R positive. Compared with 2 of 17 cases without recurrence, uPA-R was positive in 15 of 17 recurrent cases (P < 0.01). In 36 cases who survived, 17 was positive for uPA-R and 15 for PA I -1, while in 12 cases who died 2 years after surgery, 12 and 9 cases were positive for uPA-R and PA I -1, respectively (P < 0.01 and < 0.05). In 15 cases positive for all three parameters, 11 had cancer invasion and 7 died in 2 years, while in the controls with negative staining 2 had invasion and none died in 2 years (P < 0.05). CONCLUSION: Expression of uPA, uPA-R and PA I -1 is increased in HCC, and uPA and uPA-R may contribute significantly to HCC invasion and metastasis. uPA-R and PA I -1 are associated with poor prognosis.

Blood Proteins↗