Biomedical subjects
Publications and source records attributed to Xue Zhang.
Malignant hyperthermia has rarely been reported in China. We report the first case of malignant hyperthermia, verified by caffeine-halothane contracture test and genetic testing, in a Chinese patient.
The concentrations of somatic coliphages (SC) and F-specific RNA bacteriophages in effluent of three wastewater treatment plants in Beijing city were detected. Somatic coliphages and F-RNA bacteriophages in source wastewater were 6.25 x 10(3) - 1.34 x 10(4) PFU x mL(-1) and 2.4 x 10 - 2.4 x 10(3) PFU x mL(-1) respectively, and the corresponding average removal rates were 72.45% - 99.89 % and 57.84% - 93.06% by the wastewater processes, and which were lower than that of faecal coliforms. Biological aerated stage appeared to be the most efficient step in reducing the numbers of phages in wastewater, but not obviously in sand filter. The result of predicted concentrations of enteroviruses according to concentrations of F-RNA bacteriophages in water show that there are 0.65 - 15.8 PFU x L(-1) of the enteroviruses in final effluent.
Chromosome 8p21-p23 harbors tumor suppressor gene(s) implicated in multiple types of cancers. To investigate the involvement of the gene(s) in the carcinogenesis of adenocarcinoma of gastric cardia, loss of heterozygosity (LOH) for microsatellite markers at chromosome 8p21-p23 was examined. Laser capture microdissection (LCM) was used to obtain homogeneous tumor cells from 19 surgical specimens. Subsequently, genomic DNA extracted from the LCM-captured cells was amplified by multiple displacement amplification. Each tumor was assessed for allelic loss using 13 microsatellite markers. An overall LOH frequency of 63.2% (12/19) was observed and the LOH frequency for individual markers varied from 25% to 55.6%. One common deleted region of about 1.2 Mb (8p22GGAA-8p22ATCT) was defined. Our data indicated that the tumor suppressor gene at chromosome 8p22 might play an important role in the development of adenocarcinoma of gastric cardia.
AIM: To investigate the water-soluble phenolic glycosides from the whole plant of Bulbophyllum odoratissimum. METHODS: Column chromatography techniques were used to isolate the chemical constituents, physico-chemical constants and spectroscopic analysis were employed for structural elucidation. RESULTS: Bulbophyllinoside (1), a new phenolic glycoside and three known compounds were isolated from the whole plant of Bulbophyllum odoratissimum Lindl. Their structures were determined as 3-hydroxyphenethyl alcohol 4-O-( 6'-O-beta-apiofuranosyl) -beta-D-glucopyranoside (1), 3-methoxyphenethyl alcohol 4-O-beta-D-glucopynanoside (2), 3, 5-dimethoxyphenethyl alcohol 4-O-alpha-D-glucopynanoside (3) and syringin (4). CONCLUSION: Bulbophyllinoside (1) is a new compound.
Alzheimer's disease is cytopathologically characterized by loss of synapses and neurons, neuritic amyloid plaques consisting of beta-amyloid (Abeta) peptides, and neurofibrillary tangles consisting of hyperphosphorylated tau protein in susceptible brain regions. Abeta, which triggers a cascade of pathogenic events including tau phosphorylation and neuronal excitotoxicity, is proteolytically derived from beta-amyloid precursor protein (APP); the pathological and physiological functions of APP, however, remain undefined. Here we demonstrate that the level of tau phosphorylation in cells and brains deficient in APP is significantly higher than that in wild-type controls, resulting from activation of cyclin-dependent kinase 5 (CDK5) but not glycogen synthase kinase 3, the two major tau kinases. In addition, we show that overexpression of APP or its non-amyloidogenic homolog amyloid precursor-like protein 1 suppresses both basal and stress-induced CDK5 activation. The ectodomain of APP, sAPPalpha, is responsible for inhibiting CDK5 activation. Furthermore, neurons derived from APP-deficient mice exhibit reduced metabolism and survival rates and are more susceptible to excitotoxic glutamate-induced apoptosis. These neurons also manifest significant defects in neurite outgrowth compared with neurons from the wild-type littermates. The observed neuronal excitotoxicity/apoptosis is mediated through a mechanism involving CDK5 activation. Our study defines a novel neuroprotective function for APP in preventing tau hyperphosphorylation via suppressing overactivation of CDK5. We suggest that CDK5 activation, through a calcium/calpain/p25 pathway, plays a key role in neuronal excitotoxicity and represents an underlying mechanism for the physiological functions of APP.
Retinitis pigmentosa is a very heterogeneous group of retinal degenerations, with multiple genes identified in each mode of inheritance. For autosomal dominant retinitis pigmentosa (ADRP), the most common gene is the rhodopsin (RHO) gene, mutations in which contribute to about 25% of ADRP in Caucasian population. To investigate the frequency and pattern of RHO point mutations in Chinese patients with ADRP, we have screened the five coding exons and splice sites of the RHO gene in 50 unrelated probands from Chinese ADRP families and 100 normal controls to identify disease-associated mutations, using conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing. Two RHO mutations, Pro347Leu and Pro327 (1-bp del), were identified each in one family, thus the frequency of RHO mutations among ADRP families in this study is less than 14% (2/50=4%, 95% confidence interval: 1-14%), lower than that in Europe and North America, which may reflect an ethnic difference between Chinese and Caucasian populations. Loss of all phosphorylation sites at the C-terminus and a highly conserved sequence QVS(A)PA may occur because of Pro327(1-bp del). CSGE was found to be a sensitive, simple and practical method for the screening of a large number of samples under highly reproducible conditions, and could be utilized in routine molecular diagnostic laboratories.
BACKGROUND: Peritoneal dissemination is the most common pattern of metastasis in advanced gastric carcinoma with serosal invasion. In the present study, we have reported the clinical relevance of a new diagnostic method with reverse transcriptase-polymerase chain reaction (RT-PCR) assay using heparanase as a target gene for 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 heparanase and conventional cytological examination were performed subsequently. RESULTS: Heparanase RT-PCR was capable of detecting at least 10 tumor cells in 10 ml peritoneal wash fluid. There was no detectable heparanase expression in normal gastric epithelial cells and peritoneal wash samples from patients with benign disease. Twenty-five (52%) patients with gastric cancer had a detectable heparanase expression. Its positive rate was 100% and 59% for the cases with clinically evident peritoneal metastasis and serosal invasion, respectively, both of which are higher than that of cytology. CONCLUSIONS: Heparanase mRNA detected in peritoneal lavaged fluid might indicate the presence of free cancer cells in peritoneal cavity. The high sensitivity of RT-PCR based heparanase assay made it a candidate molecular marker for detecting peritoneal micrometastasis.
RNA interference (RNAi) has been successfully applied in suppression of Hepatitis B virus (HBV) replication. To circumvent the problem that mutation in HBV genome may result in resistance when siRNA is further developed as an anti-viral drug, in this study, we established a dual small interfering RNA (siRNA) expression system, which could simultaneously express two different siRNA molecules that can specifically target two genes. To test the effectiveness of this system, we applied this new approach to express simultaneously two different 21-bp hairpin siRNA duplexes that specifically attack the HBs and HBx genes of HBV, respectively, in Bel-7402 and HepG2.2.15 cells. Results indicated that dual siRNA could simultaneously inhibit the expression of HBs and HBx gene by 83.7% and 87.5%, respectively, based on luciferase assays. In addition, dual siRNA molecules were able to significantly reduce the amount of HBV core associated DNA, which is considered as an intracellular replicative intermediate, and the viral DNA in culture supernatant. Therefore, this dual siRNA system provides a more powerful tool for the study of gene function and implicates a potential application in the treatment of viral infection.
Coumarin and thiocoumarin, which are usually thermally unreactive for dimerization, were dimerized in their inclusion crystalline complexes under thermal and high vacuum conditions.
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Severe acute respiratory syndrome (SARS) caused by SARS-associated coronavirus (SARS-CoV) is a fatal disease. Prevention of future outbreaks is essential and requires understanding pathogenesis and evolution of the virus. We have isolated a SARS-CoV in China and analyzed 47 SARS-CoV genomes with the aims to reveal the evolution trends of the virus and provide insights into understanding pathogenesis and SARS epidemic. Specimen from a SARS patient was inoculated into cell culture. The presence of SARS-CoV was determined by RT-PCR and confirmed by electron microscopy. Virus was isolated followed by the determination of its genome sequences, which were then analyzed by comparing with other 46 SARS-CoV genomes. Genetic mutations with potential implications to pathogenesis and the epidemic were characterized. This viral genome consists of 29,728 nucleotides with overall organization in agreement with that of published isolates. A total of 348 positions were mutated on 47 viral genomes. Among them 22 had mutations in more than three genomes. Hot spots of nucleotide variations and unique trends of mutations were identified on the viral genomes. Mutation rates were different from gene to gene and were correlated well with periodical or geographic characteristics of the epidemic.
Tumor invasion and metastasis are the most common causes of death in gastric carcinoma. Human heparanase influences tumor invasiveness and angiogenesis. Analysis of its expression in gastric carcinoma has been hindered by our inability to procure pure cancer cells from heterogeneous tissue. In the present study, we analyzed heparanase expression in human primary and metastatic gastric carcinoma cells as well as in paired normal gastric epithelial cells by laser capture microdissection coupled with reverse transcription-polymerase chain reaction (RT-PCR). Tumor tissues, metastatic lymph nodes, and apparently uninvolved normal gastric tissues were collected from 30 patients who had undergone gastrectomy with radical lymph node dissection for gastric carcinoma without preoperative treatment. Bulk tissues and laser capture microdissected cell groups were separately subjected to RT-PCR analysis with heparanase-specific primers. For bulk tissues, heparanase-specific transcripts were detectable in all primary tumor tissues, metastatic lymph nodes, and almost all matching normal tissues. RT-PCR analysis after laser capture microdissection showed no detectable heparanase expression in matching normal epithelial cell groups. Of the laser capture microdissected primary gastric carcinoma cells, 47% (14/30) were heparanase positive. Expression was closely associated with greater tumor invasiveness, including Borrmann gross type and depth of wall infiltration. For metastatic cell groups dissected from lymph nodes, 95% showed clear heparanase expression. Furthermore, the extent of lymphatic spread was directly correlated to heparanase expression at the primary site. In conclusion, laser capture microdissection coupled with RT-PCR is a reliable approach for molecular analysis of heparanase expression in gastric carcinoma. Heparanase may facilitate invasion and metastasis of gastric carcinoma cells.
Phytochemical study of the ethanol extract of the seeds of Aesculus assamica led to the isolation of two new triterpenoid saponins. The structure of the new compounds were elucidated on the basis of spectral data to be 28-O-acetyl-21-O-(4-O-angeloyl)-6-deoxy-beta-glucopyranosyl-3-O-[beta-glucopyranosyl(1-2)-O-[beta-glucopyranosyl(1-4)]-beta-glucuronopyranosyl]protoaescigenin (1), and 21-O-(4-O-angeloyl)-6-deoxy-beta-glucopyranosyl-3-O-[beta-glucopyranosyl(1-2)-O-[beta-glucopyranosyl(1-4)]-beta-glucuronopyranosyl]protoaescigenin (2). Their in vitro bioactivity against plant pathogenic fungus Pyricularia oryzae and cytotoxicity against K562 and HCT-15 cell lines were evaluated.
OBJECTIVE: Synpolydactyly (SPD, MIM 186000), also known as syndactyly type II, is a dominantly inherited limb malformation with incomplete penetrance and variable expressivity. Polyalanine tract expansion in HOXD13 has been shown to be the disease-causing mutation in SPD. The present study was designed to identify mutation in HOXD13 and to provide prenatal diagnosis, in a large Chinese SPD family consisting of 54 individuals. METHODS: The proband and 4 other affected individuals in the family were evaluated physically and radiologically to ascertain the SPD phenotype. Genomic DNA was extracted from peripheral blood samples obtained from 18 family members (9 affected and 9 unaffected), and from amniotic fluid and chorionic villus samples obtained from the proband during her two consecutive pregnancies. With the use of a pair of specific primers, a fragment of 161bp was amplified by polymerase chain reaction (PCR) to cover the imperfect GCN triplet repeat sequence in exon 1 of HOXD13 encoding the 15-residue polyalanine tract. The PCR products were detected by agarose gel electrophoresis, and sequenced after cloning into pMD18T vector. To confirm prenatal diagnosis, haplotype analysis was also performed by allele-typing three microsatellite markers, including the intronic CA repeats in HOXD13. RESULTS: Digital and radiographic findings indicated a typical SPD phenotype in the family. These included 3/4 finger syndactyly and 4/5 toe syndactyly with an extra digit in the syndactylous web. Unilateral finger syndactyly in the proband, unilateral toe syndactyly in 2 individuals, bilateral brachydactyly of the fifth toes in 1 individual, and clinodactyly of the fifth fingers in 4 individuals were also observed, indicating variable expressivity. Gel electrophoresis of the PCR products showed an additional longer fragment in all 9 affected individuals but not in the unaffected ones. Sequence analysis of the longer fragment revealed a 9-alanine expansion. The expansion was detectable in DNA from the amniotic fluid and chorionic villus samples. Furthermore, haplotype analysis ruled out potential contamination of the maternal DNA. These suggested that the two fetuses carried the same polyalanine expansion. CONCLUSION: HOXD13 polyalanine expansion was detected in a large Chinese family with SPD and prenatal diagnosis of two affected fetuses was achieved. This is the first report on prenatal diagnosis of SPD by detecting the HOXD13 polyalanine expansion in the Han population of the Chinese mainland.
OBJECTIVE: To evaluate the prevalence of rhodopsin (RHO) mutations and the genotype-phenotype relationships in Chinese patients with autosomal dominant retinitis pigmentosa (ADRP) by conformation sensitive gel electrophoresis (CSGE) and direct DNA sequencing. METHODS: We have screened the five coding exons and splice sites of RHO gene in 27 probands who had no relativity from Chinese ADRP families and 100 normal controls to identify disease-associated mutations, using CSGE and direct DNA sequencing. Family members of some probands with disease-associated mutations were also genotyped to determine whether the RHO mutations segregated with retinitis pigmentosa (RP) in their families. RESULTS: Two RHO mutations, Pro347Leu and Pro327 (1-bp del), were identified separately in two families, thus the frequency of RHO mutations among this set of Chinese ADRP families is about 7.4% (2/27). Pro347Leu mutation was found in one ADRP proband as well as three her children who also had RP. She had relatively early onset at about 17 years. The only one child without this mutation had no symptom or sign of RP at age of 34. Pro327 (1-bp del) was identified in a late-onset ADRP patient, who appeared night blindness around 30 years old and in her fifties electroretinogram (ERG) has been flat in both scotopic and photopic phases. Family analysis showed that this mutation also existed in her younger daughter and her elder sister, both of them also had RP. Three other family members were genotypically and phenotypically normal. Neither of the two mutations was detected in 100 normal controls. CONCLUSIONS: The frequency of RHO mutations in Chinese patients was lower than that in Europe and North America. The phenotype of the patients with Pro347Leu corresponded to type 1 ADRP, with severe rod degeneration and some cone preservation later, while the phenotype of the patients carrying Pro327 (1-bp del) corresponded to type 2 ADRP, with a concomitant loss of rod and cone visual function. CSGE was found to be a sensitive, simple, and practical method for the screening of a large number of samples under highly reproducible conditions, and could be utilized in routine molecular diagnostic laboratories.
OBJECTIVE: To investigate the expression of two major alternative transcripts of RASSF1 gene (RASSF1A and RASSF1C) in human primary ovarian cancers and their biological implication as a new tumor suppressor gene. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) and laser capture microdissection (LCM) were used to determine mRNA expression of the two major alternative transcripts of RASSF1 gene (RASSF1A and RASSF1C) in 3 ovarian cancer cell lines and 80 cases of primary ovarian cancers. RESULTS: RASSF1A mRNA was undetectable in SK-OV-3 cell line. Expression of RASSF1A and RASSF1C in 80 primary ovarian cancers were 40.0% (32/80) and 91.3% (73/80) respectively. RASSF1A mRNA expression was detectable more frequently in stage I and II (71.4%, 10/14; 75.0%, 9/12) than in stage III and IV ovarian cancers (26.7%, 12/45; 14.1%, 1/9) (P < 0.05). The expression level was also higher in well and moderately differentiated tumor groups (58.6%, 17/29; 50.0%, 10/20) than in poorly differentiated tumor group (16.1%, 5/31) (P < 0.05). CONCLUSION: There is a preferential loss of RASSF1A expression in human ovarian cancers and its expression is correlated with the tumor stage and the degree of histological differentiation which, as a tumor suppressor gene, might play an important role in the tumorigenesis of human primary ovarian cancer.
STK15 (Serine/Threonine protein kinase 15) is a serine/threonine kinase encoding gene, whose overexpression in mammalian cells leads to centrosome amplification, chromosomal instability, and oncogenic transformation. 91A-->T, a single nucleotide polymorphism (SNP) in exon 3 of STK15, has recently been shown to be associated with human cancer susceptibility. Within exon 3 of STK15, there are three nonsynonymous SNPs: 91 A-->T, 169G-->A and 311C-->T. We have determined STK15 genotypes and haplotypes composed of 91A-->T and 169G-->A by PCR-RFLP in a randomly sampled cohort of 193 normal individuals from Northeast China. DNA samples from all individuals were subjected to first round of PCR using a pair of specific primers. For the subsequent nested PCR,a mismatch forward primer, which could introduce an EcoR I restriction site to the 91A allele, was included. The nested PCR products were digested with the restriction endonucleases EcoRI and AccII. The double restriction digests were separated by polyacrylamide gel electrophoresis. Three haplotypes,91A-169G, 91T-169A and 91T-169G, were detected and their frequencies were 68.65%, 10.88% and 20.47%, respectively. Six genotypes composed of the above three haplotypes were found,and their frequencies were 91A-169G/91 A-169G (46.11%), 91A-169G/91 T-169A (14.51%), 91A-169G/91T-169G (30.57%), 91T-169G/91T-169G (3.11%), 91T-169G/91T-169A (4.15%), 91T-169A/91T-169A (1.55%). Whereas no 91A-169A haplotype was detected in all individuals examined in the current study, linkage disequilibrium (LD) between the two SNPs was found.
OBJECTIVE: To investigate hypermethylation of promoter region of RASSF1A and its relationship with ovarian malignant epithelial tumors. METHODS: Methylation-specific PCR (MSP) was used to determine the hypermethylation of promoter region of ras association domain family 1 (RASSF1A) gene in 80 cases of ovarian malignant epithelial tumors. RESULTS: No methylation of promoter region of RASSF1A gene was found in all 80 normal control tissues (0). Of 80 ovarian malignant epithelial tumors 42 were hypermethylated in promoter region of RASSF1A gene (52.5%). There was no statistically significant difference in the frequency of hypermethylation of RASSF1A gene among serious adenocarcinomas, mucinous adenocarcinomas and endometrioid adenocarcinomas (54.2%, 52.4% and 45.5%, respectively; P > 0.05). Hypermethylation of RASSF1A gene happened more often in tumors in stage III and IV (66.7% and 77.8%) than that in stage I and II (21.4% and 16.7%; P < 0.05). It was less frequently observed in well and moderately differentiated tumors (34.5% and 35.0%) than in poorly differentiated tumors (80.6%; P < 0.05). CONCLUSION: High frequency of methylation of RASSF1A promoter exists in ovarian malignant epithelial tumors as a tumor suppressor gene, its suppressor activity may be abrogated by an epigenetic mechanism. Hypermethylation of RASSF1A promoter in patients with epithelial malignant ovarian tumors is related to clinical stage and histopathological grade. It indicates poor prognosis.