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Biomedical subjects

Xue Zhang

Publications and source records attributed to Xue Zhang.

At least 55 records · Page 3Linked to original sources
PubMed2004

Inactivation of dengue virus by methylene blue/narrow bandwidth light system.

Peracetic acid was one of the most commonly used disinfectants on solid surfaces in hospitals or public places. However, peracetic acid is an environmental toxin. Therefore, safer, alternative disinfectants or disinfectant systems should be developed. Because photodynamic virus inactivation with methylene blue (MB)/light system has proven effective in blood banking, MB was selected as a photosensitizing agent, dengue virus as a model virus for enveloped RNA viruses, and an in-house fabricated narrow bandwidth light system overlapping the absorption spectrum of MB as the light source. Dengue virus was mixed with different concentrations of MB, and illuminated by the narrow bandwidth light system under different illumination distances and times. The amount of dengue virus remaining was evaluated by plaque forming assays. Results showed that the concentration of MB working solution, illumination intensity of light source, illumination distance and time were four key factors affecting efficiency of virus inactivation using the MB/narrow bandwidth light system. Dengue virus could be completely inactivated at 2.5 m in 5 min when MB >/= 1.0 microg/ml. However, when the distance reached 3.0 m, only greater concentrations of MB (2.0 microg/ml) could completely inactivate virus in a reasonably short time (20 min), and smaller concentrations of MB (1.0 microg/ml) could only completely inactivate virus using longer times (25 min). The results of this virus inactivation model indicate that our MB/narrow bandwidth light system provides a powerful, easy way to inactivate dengue viruses.

Dengue Virus↗
PubMed2004

Expression of survivin in primary and metastatic gastric cancer cells obtained by laser capture microdissection.

AIM: Survivin, a recently identified member of the inhibitor of apoptosis protein family, is expressed during development and in various human cancers. However, its expression in normal tissues and clinical relevance in cancers are still debated. In the present study, we analyzed the expression of the survivin gene in human primary and metastatic gastric cancer cells as well as in paired epithelial cells from normal gastric mucosa by means of a novel laser capture microdissection (LCM) technique coupled with reverse transcription-polymerase chain reaction (RT-PCR). METHODS: Thirty patients who had undergone gastrectomy with lymph node dissection for gastric cancer without preoperative treatments were included. Neoplastic tissue, metastatic lymph nodes, and apparently uninvolved normal tissue were collected from each patient. LCM-captured "pure" cell groups were respectively subjected to RT-PCR analysis with primers specific for the survivin gene. RESULTS: Of the paired samples from 30 gastric cancer patients studied, 24 (80%) primary gastric cancer cell groups and 7 (23%) adjacent morphologically "normal" gastric epithelial cell groups were shown to have a detectable survivin expression. There was a statistically significant difference in suvivin expression between these two groups (P<0.01). Meanwhile, 95% (19/20) of the metastatic gastric cancer cell groups from lymph nodes had a clear expression of te survivin gene. However, no significant correlation between survivin expression and clinicopathological features of gastric cancer was observed in the present study. CONCLUSION: Survivin expression is present in the majority of gastric cancer cell groups obtained by LCM techniques. The high expression rate in metastatic lesions suggests a possible role of survivin in cancer invasiveness and metastasis. It may contribute to the detection of gastric cancer micrometastasis as a potential molecular marker. In addition, the high expression percentage renders survivin a potential target in the therapy for gastric cancer.

Adult↗
PubMed2004

[A de nono I462S mutation in the KRT6A gene is associated with pachyonychia congenita type I].

OBJECTIVE: To analyze the KRT6A gene mutation and mutating patterns in a sporadic Chinese patient with Pachyonychia congenita (PC)-1 so as to provide a basis for gene diagnosis and genetic counseling of this disorder. METHODS: Genomic DNA was extracted from whole blood by standard methods from a female patient with PC-1 and her parents, and from 50 normal, unrelated individuals. Primers for specific amplification of the structural KRT6A gene without co amplification of homologous genes were designed and synthesized. All exons of the gene and their flanking intronic sequences were amplified using polymerase chain reaction (PCR) and subjected to automatic DNA sequencing. The mutation was confirmed by Mbo I restriction digestion of the KRT6A-specific PCR products. RESULTS: Direct sequencing of the PCR products revealed a novel heterozygous missense mutation, I462S in the KRT6A gene, which resulted from T to G transversion at nucleotide 1385 (1385T > G) in exon 7 was detected in the patient. This mutation would result in the substitution of Isoleucine by Serine at codon 462 (I462S) located in the end 2B domain of keratin 6A. No such mutation was found in the patient's parents by sequencing of PCR products and this mutation was confirmed in the patient and excluded from both parents and 50 normal, unrelated controls by restriction analysis of PCR fragments using Mbo I enzyme. CONCLUSIONS: A de novo missense mutation in the KRT6A gene, I462S, has been found in a sporadic PC-1 patient. The identification of this novel mutation in the KRT6A gene provides further evidence that mutation in the KRT6A gene causes PC-1 phenotype.

Base Sequence↗
PubMed2004

Ligand-dependent activation of Slo family channels is defined by interchangeable cytosolic domains.

Large-conductance Ca2+- and voltage-regulated K+ channels (Slo1 BK-type) are controlled by two physiological stimuli, membrane voltage and cytosolic Ca2+. Regulation by voltage is similar to that in voltage-dependent K+ channels, arising from positively charged amino acids primarily within the S4 transmembrane helices. The basis for regulation by Ca2+ remains controversial. One viewpoint suggests that the extensive cytosolic C terminus contains the Ca2+ regulatory machinery, whereas another suggests that the pore-forming module contains the Ca2+-sensing elements. To address this issue, we take advantage of another Slo family member, the pH-regulated homolog Slo3. We reason that if the ligand-sensing apparatus is uniquely associated with a particular domain (either the pore or the cytosolic domain), exchange of those domains between Slo1 and Slo3 should result in exchange of ligand dependence in association with the key domain. The results show that the Slo3 cytosolic module confers pH-dependent regulation on the Slo1 pore module, whereas the Slo1 cytosolic module confers Ca2+-dependent regulation on the Slo3 pore module. Thus, ligand-specific regulation is defined by interchangeable cytosolic regulatory modules.

Animals↗
PubMed2004

Effect of cyclin G2 on proliferative ability of SGC-7901 cell.

AIM: To study the effect of cyclin G2 on proliferation of gastric adenocarcinoma cell line-SGC-7901 cell in vitro. METHODS: By use of cation lipofectamine transfection reagent, the pIRES-G2 and pIRESneo plasmids were transferred into SGC-7901cell line. Anticlones were selected by G418. Positive clones were observed and counted using Giemsa staining. Cell proliferative ability was assayed by MTT. RESULTS: (1) The clone number of pIRES-G2 group decreased, clone volume reduced. The number of cell clones in pIRESneo group was 87+/-3, that of pIRES-G2 group was 53+/-4, occupying 60.1% of pIRESneo group, there was significant difference obviously (P<0.01, t=15.45). (2) The average absorbance of clone cell obtained by stable transfection of pIRES-G2 at 570 nm was 1.6966+/-0.2125, the average absorbance of clone cell obtained by stable transfection of pIRESneo at 570 nm was 2.1182+/-0.3675, there was significant difference between them (P<0.01, t=3.412). CONCLUSION: Cyclin G2 can inhibit SGC-7901cell proliferative ability obviously, it may be a negative regulator in cell cycle regulation.

Adenocarcinoma↗
PubMed2004

Interaction of the CDK2-associated protein-1, p12(DOC-1/CDK2AP1), with its homolog, p14(DOC-1R).

Human DOC-1/CDK2AP1 gene encodes a growth suppressor protein of 12kDa (p12(DOC-1/CDK2AP1)). Recently, p12(DOC-1/CDK2AP1) has been shown to associate with cell cycle proteins including CDK2 and DNA polymerase alpha/primase. It negatively regulates CDK2 activities and suppresses DNA replication. Therefore, identification of other p12(DOC-1/CDK2AP1) interacting proteins might clarify its role in the cell cycle regulation and carcinogenesis. The purpose of this study was to identify additional p12(DOC-1/CDK2AP1) interacting proteins using the yeast two-hybrid system. Using human p12(DOC-1/CDK2AP1) as a bait in a liver cDNA library screening, cDNA clones identical to human DOC-1R transcript were identified. The interaction between p12(DOC-1/CDK2AP1) and p14(DOC-1R) was verified in vitro and in cells. GST pull-down assay and immunoprecipitation experiments confirmed the interaction between the two proteins. The critical region for p12(DOC-1/CDK2AP1)'s interaction with p14(DOC-1R) was defined to amino acids 20-25 by using a series of deletion mutants as baits in the yeast two-hybrid system. Our data indicated that p12(DOC-1/CDK2AP1) could associate with its homologous protein, p14(DOC-1R).

Amino Acid Sequence↗
PubMed2004

A novel piezoelectric quartz micro-array immunosensor based on self-assembled monolayer for determination of human chorionic gonadotropin.

A novel multi-channel 2 x 5 model of piezoelectric quartz micro-array immunosensor has been developed for quantitative detection of human chorionic gonadotropin (hCG) in serum or urine samples. Every crystal unit of the fabricated piezoelectric hCG micro-array immunosensor can oscillate independently without interfering each other. A 2 x 5 model of micro-array immunosensor as compared with a one-channel immunosensor can provide eight times higher detection speeds for hCG assay. The anti-hCG antibody is deposited on the gold electrode's surface of 10 MHz quartz AT-cut crystal by self-assembled technique using sulfosuccinimidyl 6-[3'-(2-pyridyldithio) propionamido] hexanoate (Sulfo-LC-SPDP), and serves as an antibody recognizing layer. The highly ordered self-assembled monolayers (SAM) ensure well-controlled surface structure and offer many advantages to the performance of the sensor. Compared with conventional antibody immobilization methods, the amount and the reaction activity of antibody monolayer coated by the SAM binding are bigger than those by the SPA method, and less non-specific binding caused by other analytes in sample is found. Under the optimized experimental conditions, the results showed that micro-array immunosensor quantitatively detected serum or urine hCG in the range of 2.5-500 mIU/ml with high precision (CV<5%); other hormones in human serum and urine did not interfere with the determination markedly. Serum and urine samples of 60 patients were detected by the micro-array immunosensor, and the results agreed well with those given by the commercial radioimmunoassay test kit, with correlation coefficient of 0.92. After regeneration with urea solution the coated immunosensor can be reused five times without appreciable loss of activity.

Biosensing Techniques↗
PubMed2004

Novel mutations of the RNA-specific adenosine deaminase gene (DSRAD) in Chinese families with dyschromatosis symmetrica hereditaria.

Dyschromatosis symmetrica hereditaria (DSH) is an autosomal dominant skin disorder. It is also called "reticulate acropigmentation of Dohi" or "symmetric dyschromatosis of the extremities". The DSH locus has recently been mapped to chromosome 1q21 and pathogenic mutations were identified in the DSRAD gene encoding double-stranded RNA-specific adenosine deaminase in Japanese patients with DSH. We report here two novel point mutations, Q513X(1537C>T) and R916W(2746C>T) in the DSRAD gene identified in two Chinese families, respectively. These data suggest that mutations in DSRAD were also associated with DSH in Chinese. This is the first report on DSRAD as the causative gene of DSH in the Chinese population.

Adenosine Deaminase↗
PubMed2004

[Identification of a recurrent mutation in the ROR2 gene in a Chinese family with brachydactyly type B].

OBJECTIVE: To identify the disease-causing mutation in a Chinese family with brachydactyly type B (BDB). METHODS: Genomic DNA was extracted from peripheral blood samples of family members. Exons 8 and 9 of the ROR2 gene were amplified by polymerase chain reaction (PCR) and sequenced directly. Furthermore, the PCR products showing mutation were cloned into pMD18T vector and the insert fragments were sequenced. RESULTS: A 1398-1399 insA heterozygous mutation was detected in the patient. This mutation had been found in German families with BDB. CONCLUSION: To the authors' knowledge, it is the first report on identification of the ROR2 pathogenic mutation in Chinese patients with BDB.

Amino Acid Sequence↗
PubMed2004

Expression of survivin mRNA in peritoneal lavage fluid from patients with gastric carcinoma.

BACKGROUND: Peritoneal dissemination is the most common pattern of metastasis in advanced gastric carcinoma with serosal invasion. In the present study, we reported the clinical relevance of a new diagnostic method involving RT-PCR, using survivin as the target gene, for the detection of free cancer cells in peritoneal washes. METHODS: Intraoperative peritoneal washes were obtained from 48 patients who underwent surgery for gastric cancer. RT-PCR analysis with primers specific for survivin and conventional cytological examinations were both performed. RESULTS: Survivin mRNA was not detected in any peritoneal wash samples from patients with benign disease, but was detected in 28 of 48 samples taken from patients with gastric cancer and in all metastatic nodules. Survivin expression in the peritoneal cavity significantly correlated with depth of cancer invasion, lymph node metastasis, and TNM stage. There were 92% of clinically evident peritoneal metastasis cases showed detectable survivin expression. The combination of survivin RT-PCR and cytological examination yielded positive results in 66.7% (32/48) of patients with gastric cancer, much higher than the results produced by cytological method alone. CONCLUSIONS: Survivin mRNA detected in peritoneal lavage fluid might indicate the presence of free cancer cells in the peritoneal cavity. The high sensitivity of the RT-PCR-based survivin assay suggests that survivin serves as a molecular marker for detecting peritoneal micrometastasis. Its ubiquitous expression in peritoneal cancer cells and metastatic nodules also suggests a promising future therapeutic strategy based on survivin inhibition for cases of gastric cancer involving peritoneal metastasis.

Adult↗
PubMed2004

Preliminary analysis of CDK2 sequence and its nuclear import.

We constructed the plasmids encoding enhanced green fluorescent protein (EGFP)-tagged wild type cyclin-dependent kinase 2(CDK2) (pEGFP-CDK2) and CDK2 deletion mutants (pEGFP-CDK2N and pEGFP-CDK2C, lacking the last C-terminal and the first N-terminal 97 amino acids of CDK2, respectively) and transfected them into HeLa cell line and CHO cell line. After synchronization, green fluorescent signals were detected mainly in nucleus of the cells transfected with pEGFP-CDK2 and predominantly in cytoplasm of the cells transfected with the two mutant CDK2 constructs. Our results suggested that there were no nuclear-import signals in CDK2 and that CDK2 nuclear import might be mediated by association with other proteins through the three-dimensional structure formed by amino acids including those from the N- and C-terminal regions of CDK2.

Active Transport, Cell Nucleus↗
PubMed2004

[Textual research on the author of Ji feng pu ji fang (Jifeng's Formularies for universal relief)].

As a medical book of the Song dynasty, there are marks of "re-collating and checking" at the head of each subject at each volume in Ji feng pu ji fang (Jifeng's Formularies for Universal Relief), thus, the book was mistakenly attributed to Zhang Rui. Based on the time characteristics, case records, medical affairs, avoidance of emperor's name, and the original draft, it should be written during the Yuanfeng reign and published during the Gaozong emperor of the Southern Song dynasty. By carefully analyzing the medical lives of Sun Zhao, who died at the end of Yuanfeng reign, Sun Zhao should be its real author, whereas Zhang Rui, who was still alive in the Shaoxing reign of the Southern Song dynasty, was not its author. The research into the medical affairs and birth date of Chu Yushi and Dong Ji's Jiao qi zhi fa zong yao (Essential for Treating Beriberi) provides a powerful evidence for this conclusion.

Books↗
PubMed2004

[Effect of irradiation on tooth hard tissue and its resistance to acid].

OBJECTIVE: To study the effect of irradiation on the susceptibility of radiation caries. METHODS: The structures of 56 teeth enamel and dentin of 63 roots were observed using SEM and the collagen fibre and the resistance to the acid were also investigated after irradiation of 30 Gy, 50 Gy and 70 Gy. RESULTS: The enamel structure changes were found after irradiation with different doses. The significant difference was found in the enamel changes between high or middle dose group and low dose group or control. The dentin morphology changed, some collagen fibre vanished and resistance to acid was reduced after irradiation with 50 Gy and 70 Gy. CONCLUSIONS: The radiation reduced the resistance of teeth to the acid and increased the caries susceptibility.

Acids↗
PubMed2004

[A Chinese girl with cleidocranial dysplasia (CCD) caused by the recurrent R190W mutation in RUNX 2].

OBJECTIVE: Cleidocranial dysplasia (CCD) is a rare skeletal disease with autosomal dominant inheritance associated with mutation in RUNX 2. The authors report a Chinese girl with CCD in whom the mutation in RUNX 2 was identified. METHODS: Clinical diagnosis was based on physical examination, radiological findings, and biochemical tests. For mutation detection, genomic DNA was extracted from peripheral blood using standard method. All 7 coding exons of RUNX 2 and their flanking intronic sequences were amplified by polymerase chain reaction (PCR), and the PCR products were then subjected to automatic DNA sequencing. RESULTS: The affected girl showed typical clinical manifestations of CCD, including patent fontanelles, absent clavicles, short stature and dental anomalies. Direct sequencing of PCR-amplified fragments revealed a recurrent missense mutation, R190W (568 C > T), in RUNX 2. The mutation was further confirmed by Hae III restriction analysis. CONCLUSION: A Chinese case of CCD was confirmed and the disease-causing mutation was linked to a recurrent point mutation in RUNX 2.

Cleidocranial Dysplasia↗
PubMed2003

GTPase regulators and photoresponses in cones of the eastern chipmunk.

Vertebrate cone and rod photoreceptor cells use similar mechanisms to transduce light signals into electrical signals, but their responses to light differ in sensitivity and kinetics. To assess the role of G-protein GTP hydrolysis kinetics in mammalian cone photoresponses, we have characterized photoresponses and GTPase regulatory components of cones and rods from the cone-dominant retina of the eastern chipmunk. Sensitivity, based on the stimulus strength required for a half-maximum response, of the M-cone population was 38-fold lower than that of the rods. The relatively lower cone sensitivity could be attributed in part to lower amplification in the rising phase and in part to faster recovery kinetics. At a molecular level, cloning of chipmunk cDNA and expression of recombinant proteins provided standards for quantitative immunoblot analysis of proteins involved in GTPase acceleration. The ratio of the cGMP-phosphodiesterase inhibitory subunit gamma to cone pigment, 1:68, was similar to the levels observed for ratios to rhodopsin in bovine retina, 1:76, or mouse retina, 1:65. In contrast, the ratio to pigment of the GTPase-accelerating protein RGS9-1 was 1:62, more than 10 times higher than ratios observed in rod-dominant retinas. Immunoprecipitation experiments revealed that, in contrast to rods, RGS9-1 in chipmunk retina is associated with both the short and long isoforms of its partner subunit G(beta5). The much higher levels of the GTPase-accelerating protein complex in cones, compared with rods, suggest a role for GTPase acceleration in obtaining rapid photoresponse kinetics.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2003

Targeted expression of the dominant-negative FGFR4a in the eye using Xrx1A regulatory sequences interferes with normal retinal development.

Molecular analysis of vertebrate eye development has been hampered by the availability of sequences that can selectively direct gene expression in the developing eye. We report the characterization of the regulatory sequences of the Xenopus laevis Rx1A gene that can direct gene expression in the retinal progenitor cells. We have used these sequences to investigate the role of Fibroblast Growth Factor (FGF) signaling in the development of retinal cell types. FGFs are signaling molecules that are crucial for correct patterning of the embryo and that play important roles in the development of several embryonic tissues. FGFs and their receptors are expressed in the developing retina, and FGF receptor-mediated signaling has been implicated to have a role in the specification and survival of retinal cell types. We investigated the role of FGF signaling mediated by FGF receptor 4a in the development of retinal cell types in Xenopus laevis. For this purpose, we have made transgenic Xenopus tadpoles in which the dominant-negative FGFR4a (Delta FGFR4a) coding region was linked to the newly characterized regulatory sequences of the Xrx1A gene. We found that the expression of Delta FGFR4a in retinal progenitor cells results in abnormal retinal development. The retinas of transgenic animals expressing Delta FGFR4a show disorganized cell layering and specifically lack photoreceptor cells. These experiments show that FGFR4a-mediated FGF signaling is necessary for the correct specification of retinal cell types. Furthermore, they demonstrate that constructs using Xrx1A regulatory sequences are excellent tools with which to study the developmental processes involved in retinal formation.

Animals↗
PubMed2003

Somatic mutation analysis of p53 and ST7 tumor suppressor genes in gastric carcinoma by DHPLC.

AIM: To verify the effectiveness of denaturing high-performance liquid chromatography (DHPLC) in detecting somatic mutation of p53 gene in gastric carcinoma tissues. The superiority of this method has been proved in the detection of germline mutations, but it was not very affirmative with respect to somatic mutations in tumor specimens. ST7 gene, a candidate tumor suppressor gene identified recently at human chromosome 7q31.1, was also detected because LOH at this site has also been widely reported in stomach cancer. METHODS: DNA was extracted from 39 cases of surgical gastric carcinoma specimen and their correspondent normal mucosa. Seven fragments spanning the 11 exons were used to detect the mutation of p53 gene and the four exons reported to have mutations in ST7 gene were amplified by PCR and directly analyzed by DHPLC without mixing with wild-type allele. RESULTS: In the analysis of p53 gene mutation, 9 aberrant DHPLC chromatographies were found in tumor tissues, while their normal-adjacent counterparts running in parallel showed a normal shape. Subsequent sequencing revealed nine sequence variations, 1 polymorphism and 8 mutations including 3 mutations not reported before. The mutation rate of p53 gene (21%) was consistent with that previously reported. Furthermore, no additional aberrant chromatography was found when wild-type DNA was added into the DNA of other 30 tumor samples that showed normal shapes previously. The positivity of p53 mutations was significantly higher in intestinal-type carcinomas (40%) than that in diffuse-type (8.33%) carcinomas of the stomach. No mutation of ST7 gene was found. CONCLUSION: DHPLC is a very convenient method for the detection of somatic mutations in gastric carcinoma. The amount of wild type alleles supplied by the non-tumorous cells in gastric tumor specimens is enough to form heteroduplex with mutant alleles for DHPLC detection. ST7 gene may not be the target gene of inactivation at 7q31 site in gastric carcinoma.

Base Sequence↗