Search PubMed⌕ Search

Biomedical subjects

Z Wang

Publications and source records attributed to Z Wang.

At least 541 records · Page 30Linked to original sources
PubMed2001

[Simultaneous determination of trace cadmium and arsenic in grains using atomic absorption spectrophotometry].

Simultaneous determination of two components in single wavelength using interferencing effect and atomic absorption spectrophotometry assisted by simulated annealing-back propagation of error-artificial neural networks algorithm was realized, and simultaneous determination of trace cadmium and arsenic in grains was studied. The results obtained are satisfactory. The recoveries found by standard addition method are 91%-98% and 87%-92% respectively. Relative standard deviations for 7 times of determinations are all less than 4%. This method is fast and simple.

Arsenic↗
PubMed2001

[Determination of Ca, Mg, K, P, Na, Zn, Fe and F in bone with microwave digest].

Microwave digest technique is widely applied in the analytical chemistry field. Comparing with traditional sample digestion method, i.e. wet digest or dry digest. microwave technique is simple, rapid, little contaminative and saves reagent, digests completely. Elements in the bone such as Ca, Mg, P, K, Na, Fe, Zn and F are determined by atomic absorption spectrometry. Their recovery ratio is 66.4%-110.9%, variation coefficient is 0.32%-7.61% except fluorine and phosphor.

Bone and Bones↗
PubMed2001

DNA damage-induced mutagenesis : a novel target for cancer prevention.

Tolerance to some degree of unrepaired DNA damage is crucial for cell survival-more specifically, for the sustained functionality of the DNA replication machinery-in the presence of adverse (genotoxic) conditions. At least two mechanisms ensure such tolerance: template switching and lesion bypass. Lesion bypass, whereby unrepaired damaged DNA serves as template, involves the Y family of DNA polymerases; lesion bypass can be error-free or error-prone, depending on the nucleotide incorporated during translesion synthesis. Error-prone lesion bypass constitutes a major mechanism of mutagenesis and, in eukaryotes, is primarily effected by the DNA polymerase zeta (Polzeta) pathway. A relationship between the Y family polymerases and the Polzeta pathway is thus implicated, and conforms to the two-polymerase two-step model of lesion bypass. Based on the mutagenesis hypothesis of cancer formation, DNA damage-induced mutagenesis and its underlying molecular biology offer an intriguing potential target for cancer prevention.

Animals↗
PubMed2001

[Study on computer aided design system of anterior prosthesis in terms of artificial neural network].

OBJECTIVE: This study was to develop computer aided design system of anterior prosthesis, which can improve information communication among doctors, technicians, patients and raise anterior prosthesis cosmetic effect. METHODS: Digital camera was used for image capture; Space field method, neighboring field average method, midst value filter method, and image average method were used for image pre-process; sample teeth were constructed; anterior prosthesis were automatically designed through tooth feature extraction. RESULTS: 86 patients were prosthetically designed through this CAD system with excellent results. CONCLUSION: This system implemented anterior prosthesis CAD rapidly, guided clinical application and promoted information process in the field of prosthetics.

English Abstract↗
PubMed2001

[Expression of T-lymphocytes and cytokines in the decidua of mifepristone with misoprostol for terminating early pregnancy].

OBJECTIVE: To investigate the expression of T-lymphocyte subsets (CD3+, CD4+, CD8+), natural killer cells (NK cells, CD56+, CD16+), tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) in mifepristone and misoprostod treated ducidua for terminating human early pregnancy. METHODS: Thirty eight women who volunteered to terminate their pregnancy were divided into 3 groups: mifepristone group (group I, n = 13), mifepristone with misoprostol group (group II, n = 12) and control group (group Il, n = 13), The expression of T-lymphocyte subsets, NK cells, TNF-alpha and TGF-beta were assessed by flow cytometry. RESULTS: The expression of CD4+ were (30.91 +/- 2.57)% and (31.58 +/- 3.28)% in group I and II respectively. Which were significantly higher than that in group III (25.64 +/- 2.36)% (P < 0.05, P < 0.01). CD56+ were (22.40 +/- 2.77)% and (26.88 +/- 3.79)% in group I and II, which were significantly higher than that in group III (18.58 +/- 4.04)% (P < 0.05, P < 0.01), CD16+ were (8.98 +/- 2.18)% and (10.84 +/- 2.51)% in group I and II, which were significantly higher than that in group III (6.34 +/- 2.01)% (P < 0.01, P < 0.001). The expression of TNF-alpha in group I and II were higher than that of group III, TGF-beta in group I and II were lower than that of group III, but there was no significant difference (P > 0.05). The expression of CD3+, CD8+, CD4+/ CD8+ ratio were not significant difference among the three groups (P > 0.05). CONCLUSIONS: Mifepristone with misoprostol for terminating early pnegnancy might be affect the expression of lymphocyte and cytokines and induce the disorder of decidual micro-environment which might be the reason of medical abortion.

Abortifacient Agents↗
PubMed2001

[The predictive value of plasma fibronectin concentration on fetal growth retardation and preeclampsia at earlier stage of the third trimester].

OBJECTIVE: To evaluate the predictive value of maternal plasma fibronectin concentration at 24-34 weeks on fetal growth retardation (FGR) and preeclampsia. METHODS: The maternal plasma fibronectin concentrations were measured by rate nephelometric procedure in the 130 initial normal nulliparous pregnant woman at 24-34 gestational weeks. The outcomes of pregnancies were followed. The predictive values of FN predicting on 3 kinds of outcome of pregnancy with FGR, preeclampsia, or FGR complicated preeclampsia were compared. RESULTS: (1) In a cohort of 130 initially normal nulliparous pregnant women, 10 cases of FGR, 10 cases of preeclampsia, and 4 cases of FGR complicated with preeclampsia were developed, and 106 cases with no complication. The maternal age, gravidity, sampling gestational ages, delivering gestational ages were not significantly different among the 4 groups (P > 0.05). (2) The plasma fibronectin levels in women with FGR, preeclampsia or FGR complicated preeclampsia [(486.45 +/- 122.69) mg/L, (428.38 +/- 118.71) mg/L and (443.66 +/- 68.13) mg/L, respectively] were significantly higher than that in the control [(284.41 +/- 93.83) mg/ L, P < 0.01]. (3) The areas under ROC of predicting on three outcomes of FGR, preeclampsia, or FGR complicated preeclampsia were 0.893, 0.818 and 0.867 respectively. (4) At the best cut point, the sensitivity, specificity, positive predictive value, negative predictive value and Kappa index of FN level predicting on the outcomes of pregnancy with three groups were 57.14%, 95.69%, 61.54%, 94.87%, 0.545 5 (on FGR); 91.27%, 50.00%, 15.38%, 98.29%, 0.1975 (on preeclampsia) and 42.86%, 91.38%, 37.50%, 92.98%, 0.3221 (on FGR complicated with preeclampsia), respectively. CONCLUSION: The maternal plasma fibronectin may be used as an earlier predictor for screening of FGR and the predictive value of FN on FGR is better than on preeclampsia.

Area Under Curve↗
PubMed2001

[Carcinogenicity of duodenogastric reflux juice in patients undergoing gastrectomy].

OBJECTIVE: To determine the carcinogenic potential of reflux juice from patients undergoing remote gastrectomy and to clarify the relationship between duodenogastric reflux and gastric stump cancer. METHODS: A total of 37 reflux juice samples (13 Billroth I, 24 Billroth II) were used. A two-stage transformation assay using BALB/c 3T3 cells was carried out to test the initiating or promoting activity of the samples. RESULTS: 11.1% reflux samples showed initiating activities, whereas 47.4% samples enhanced the MNNG-initiating cell transformation, suggesting that duodenogastric reflux juice might possess tumor-promoter activity (P < 0.05). There was no difference in initiating activities of the samples irrespective of surgical procedures (P > 0.05). Billroth II samples exhibited stronger tumor-promoter activity than Billroth I samples (P < 0.05), in accordance with many epidemic findings that this cancer preferred to Billroth II procedure. The promoter activities were well correlated with the histological changes of the stomas (r(s) = 0.625, P < 0.01), but both their cytotoxicities and initiating activities failed to show this correlation. CONCLUSIONS: The duodenogastric reflux juice from patients undergoing remote gastrectomy has tumor-promoting activity on initiating activity. It is suggested that tumor-promoting potential should be responsible for the high incidence of gastric carcinoma in the patients undergoing remote gastrectomy. Thus a direct evidence for the etiology of gastric stump carcinoma is provided.

Adult↗
PubMed2000

Tissue inhibitor of metalloproteinase (TIMP)-2 acts synergistically with synthetic matrix metalloproteinase (MMP) inhibitors but not with TIMP-4 to enhance the (Membrane type 1)-MMP-dependent activation of pro-MMP-2.

The membrane-type 1 matrix metalloproteinase (MT1-MMP) has been shown to be a key enzyme in tumor angiogenesis and metastasis. MT1-MMP hydrolyzes a variety of extracellular matrix components and is a physiological activator of pro-MMP-2, another MMP involved in malignancy. Pro-MMP-2 activation by MT1-MMP involves the formation of an MT1-MMP.tissue inhibitors of metalloproteinases 2 (TIMP-2). pro-MMP-2 complex on the cell surface that promotes the hydrolysis of pro-MMP-2 by a neighboring TIMP-2-free MT1-MMP. The MT1-MMP. TIMP-2 complex also serves to reduce the intermolecular autocatalytic turnover of MT1-MMP, resulting in accumulation of active MT1-MMP (57 kDa) on the cell surface. Evidence shown here in Timp2-null cells demonstrates that pro-MMP-2 activation by MT1-MMP requires TIMP-2. In contrast, a C-terminally deleted TIMP-2 (Delta-TIMP-2), unable to form ternary complex, had no effect. However, Delta-TIMP-2 and certain synthetic MMP inhibitors, which inhibit MT1-MMP autocatalysis, can act synergistically with TIMP-2 in the promotion of pro-MMP-2 activation by MT1-MMP. In contrast, TIMP-4, an efficient MT1-MMP inhibitor, had no synergistic effect. These studies suggest that under certain conditions the pericellular activity of MT1-MMP in the presence of TIMP-2 can be modulated by synthetic and natural (TIMP-4) MMP inhibitors.

Animals↗
PubMed2000

Inhibition of Trypanosoma brucei gene expression by RNA interference using an integratable vector with opposing T7 promoters.

RNA interference is a powerful method for inhibition of gene expression in Trypanosoma brucei (Ngo, H., Tschudi, C., Gull, K., and Ullu, E. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 14687-14692). Here we describe a vector (pZJM) for in vivo tetracycline-inducible synthesis of double-stranded RNA (dsRNA) in stably transformed cells. The dsRNA is synthesized from opposing T7 promoters. We tested the vector with genes involved in processes such as kinetoplast DNA replication, mitochondrial mRNA synthesis, glycosyl phosphatidylinositol biosynthesis, glycosome biogenesis, and polyamine biosynthesis. In most cases the induction of dsRNA caused specific and dramatic loss of the appropriate mRNA, and in many cases there was growth inhibition or cell death. One striking phenotype was the loss of kinetoplast DNA after interference with expression of a topoisomerase II. The gene being analyzed by this procedure need not even be fully sequenced. In fact, many of the genes we tested were derived from partial sequences in the T. brucei genome data base that were identified by homology with known proteins. It takes as little as 3 weeks from identification of a gene sequence in the data base to the appearance of a phenotype.

Animals↗
PubMed2000

Genetic diversity of hantaviruses isolated in china and characterization of novel hantaviruses isolated from Niviventer confucianus and Rattus rattus.

The antigenic and genetic properties of 46 hantaviruses from China, 13 from patients, 23 from rodents, and 10 from unknown hosts, were compared with those of other hantaviruses. The viruses were classified as either Hantaan (HTN) or Seoul (SEO) viruses. A phylogenetic analysis of the partial M (300 bp) and S (around 485 bp) genomes of HTN viruses identified nine distinct genetic subtypes, one consisting of isolates from Korea. The SEO viruses were divided into five genetic subtypes, although they had less variability than the HTN subtypes. There was a correlation between the subtype and province of origin for four subtypes of HTN viruses, confirming geographical clustering. Hantaan virus NC167 isolated from Niviventer confucianus and SEO virus Gou3 isolated from Rattus rattus were the basal clades in each virus. The phylogenetic trees constructed from the entire S and M segments suggested that NC167 was introduced to N. confucianus in a host-switching event. The reactivity of a panel of 35 monoclonal antibodies was almost exactly the same in NC167 and a representative HTN virus and in Gou3 and a representative SEO virus. However, there was a one-way cross-neutralization between them. These results confirm the varied nature of Murinae-associated hantaviruses in China.

Animals↗
PubMed2000

A stable complex of a novel transcription factor IIB- related factor, human TFIIIB50, and associated proteins mediate selective transcription by RNA polymerase III of genes with upstream promoter elements.

Transcription factor IIIB (TFIIIB) is directly involved in transcription initiation by RNA polymerase III in eukaryotes. Yeast contain a single TFIIIB activity that is comprised of the TATA-binding protein (TBP), TFIIB-related factor 1 (BRF1), and TFIIIB", whereas two distinct TFIIIB activities, TFIIIB-alpha and TFIIIB-beta, have been described in human cells. Human TFIIIB-beta is required for transcription of genes with internal promoter elements, and contains TBP, a TFIIIB" homologue (TFIIIB150), and a BRF1 homologue (TFIIIB90), whereas TFIIIB-alpha is required for transcription of genes with promoter elements upstream of the initiation site. Here we describe the identification, cloning, and characterization of TFIIIB50, a novel homologue of TFIIB and TFIIIB90. TFIIIB50 and tightly associated factors, along with TBP and TFIIIB150, reconstitute human TFIIIB-alpha activity. Thus, higher eukaryotes, in contrast to the yeast Saccharomyces cerevisiae, have evolved two distinct TFIIB-related factors that mediate promoter selectivity by RNA polymerase III.

Base Sequence↗
PubMed2000

Methane emission from a simulated rice field ecosystem as influenced by hydroquinone and dicyandiamide.

A simple apparatus for collecting methane emission from a simulated rice field ecosystem was formed. With no wheat straw powder amended all treatments with inhibitor(s) had so much lower methane emission during rice growth than the treatment with urea alone (control), which was contrary to methane emission from the cut rice-soil system. Especially for treatments with dicyandiamide (DCD) and with DCD plus hydroquinone (HQ), the total amount of methane emission from the soil system and intact rice-soil system was 68.25-46.64% and 46.89-41.78% of the control, respectively. Hence, DCD, especially in combination with HQ, not only increased methane oxidation in the floodwater-soil interface following application of urea, but also significantly enhanced methane oxidation in rice root rhizosphere, particularly from its tillering to booting stage. Wheat straw powder incorporated into flooded surface layer soil significantly weakened the above-mentioned simulating effects. Regression analysis indicated that methane emission from the rice field ecosystem was related to the turnover of ammonium-N in flooded surface layer soil. Diminishing methane emissions from the rice field ecosystem was significantly beneficial to the growth of rice.

Agriculture↗
PubMed2000

Detection of telomerase activity in prostatic fluid specimens.

We report here the extended use of the telomeric repeat amplification protocol (TRAP) assay for the detection of telomerase activity in fresh prostatic fluid obtained from anesthetized patients. Telomerase activity was detected in pellet extract and/or supernatant fluid of specimens obtained from 25 of 30 prostate cancer (PCa) patients (83%), whereas no activity was similarly detectable in specimens taken from 8 of 9 patients (89%) without clinical evidence of PCa. The positive predictive value (PPV) of the TRAP assay for PCa in this pilot study was 96%. We found a strong correlation between telomerase activity in prostatic fluid specimens and serum prostate specific antigen (PSA) values. Telomerase activity was found in 84% of specimens from patients with PSA values >4 ng/ml, whereas in specimens from patients with PSA values </=4 ng/ml, only 29% tested positive for telomerase activity. In patients with PSA values above the standard 0 to 4 ng/ml reference range, the PPV of the TRAP assay was 84%. Furthermore, telomerase activity could be detected in 85% of the specimens from PCa patients with Gleason scores >4. In prostatic fluid from PCa patients with Gleason scores of </=4, telomerase activity was detected 50% of the time. The PPV was 92% when a Gleason score of 4 was used as the lower limit. This pilot study raises the possibility of utilizing telomerase activity as an aid in PCa detection.

Journal Article↗
PubMed2000

Nuclear factor 1 (NF1) affects accurate termination and multiple-round transcription by human RNA polymerase III.

We have shown previously that the TFIIIC1/TFIIIC1' fraction interacts specifically with the VA1 terminator regions to affect both termination and initiation/reinitiation of transcription by human RNA polymerase III. Here, we further purified the VA1 terminator-binding factor to apparent homogeneity and found, by peptide sequence analysis, that it belongs to the NF1 protein family. NF1 interacts specifically with the NF1-binding sites within the terminator regions of the VA1 gene and with two subunits (TFIIIC220 and TFIIIC110) of human TFIIIC2. Immunodepletion with anti-NF1 antibodies dramatically decreases transcription from the VA1 template in nuclear extract, and mutation at the NF1-binding site in the terminator region of the VA1 gene selectively affects multiple-round transcription (reinitiation of transcription) and termination. In addition, NF1 acts in conjunction with TFIIIC to promote accurate termination by RNA polymerase III on a C-tailed VA1 template.

Base Sequence↗
PubMed2000

Regulation of somatic growth by the p160 coactivator p/CIP.

A family of p160 coactivators was initially identified based on ligand-dependent interactions with nuclear receptors and thought to function, in part, by recruiting CREB-binding protein/p300 to several classes of transcription factors. One of the p160 factors, p/CIP/AIB1, often amplified and overexpressed in breast cancer, also exhibits particularly strong interaction with CREB-binding protein/p300. In this manuscript, we report that p/CIP, which exhibits regulated transfer from cytoplasm to nucleus, is required for normal somatic growth from embryonic day 13.5 through maturity. Our data suggest that a short stature phenotype of p/CIP gene-deleted mice reflect both altered regulation of insulin-like growth factor-1 (IGF-1) gene expression in specific tissues and a cell-autonomous defect of response to IGF-1, including ineffective transcriptional activities by several classes of regulated transcription factors under specific conditions. The actions of p/CIP are therefore required for full expression of a subset of genes critical for regulating physiological patterns of somatic growth in mammals.

Animals↗
PubMed2000

Synthesis, characterization, and activity of metabolites derived from the cyclooxygenase-2 inhibitor rofecoxib (MK-0966, Vioxx).

Metabolites of the COX-2 inhibitor rofecoxib (MK-0966, Vioxx) were prepared by synthetic or biosynthetic methods. Metabolites include products of oxidation, glucuronidation, reduction and hydrolytic ring opening. Based on an in vitro whole blood assay, none of the known human metabolites of rofecoxib inhibits COX-1 nor contributes significantly to the inhibition of COX-2.

Animals↗