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Dan Wu

Publications and source records attributed to Dan Wu.

49 records · Page 3Linked to original sources
PubMed2004

Detection of C677T mutation in methylenetetrahydrofolate reductase gene by denaturing high performance liquid chromatography.

In this paper, we described an assay for the detection of the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene using denaturing high-performance liquid chromatography (DHPLC). The conditions for DHPLC analysis were systematically investigated based on a general HPLC instrument (Prostar VARIAN). A 225 bp DNA fragment covering the 677 site of MTHFR gene was amplified by PCR technology using the purified DNA from whole blood or whole blood as template DNA. PCR products were directly injected without the need for purification. The C677T mutation could be clearly distinguished by DHPLC technology. Our data demonstrated that DHPLC was a powerful and alternative tool for detection of genetic variants and single-nucleotide polymorphisms to electrophoresis technology.

Base Sequence↗
PubMed2004

A pair of two-component regulatory genes ecrA1/A2 in S. coelicolor.

Two-component genes are kinds of genetic elements involved in regulation of antibiotic production in Streptomyces coelicolor. DNA microarray analysis revealed that ecrA1/A2, which mapped at distant sites from red locus and encode respectively the kinase and regulator, expressed coordinately with genes of Red specific biosynthetic pathway. ecrA1 and ecrA2 gene-disruptive mutants were constructed using homogenotisation by reciprocal double crossover. Fermentation data showed that the undecylprodigiosin (Red) level of production was lower than that of wild-type strain. However, the change of the actinorhodin (Act) production level was not significant compared with wild type. Thus, these experiment results confirmed that the two-component system ecrA1/A2 was positive regulatory element for red gene cluster.

Anthraquinones↗
PubMed2004

Prognostic value of EphA2 and EphrinA-1 in squamous cell cervical carcinoma.

OBJECTIVES: To analyze the expressions of the protein and mRNA of EphA2 and EphrinA-1 in squamous cell cervical carcinomas and explore their prognostic value in cervical carcinoma. METHODS: Immunohistochemistry was used to assess the protein expressions of EphA2 and EphrinA-1 in 206 patients with squamous cervical carcinoma FIGO stage Ia-IVb. Frozen tissues from 20 cases in which the tumors showed variable EphA2 and EphrinA-1protein expressions were used for laser capture microdissection (LCM). About 50 cancer cells in each frozen section were captured with the LCM method and processed for RT-PCR detection of EphA2 and EphrinA-1 mRNA. RESULTS: Among the 206 squamous cervical carcinomas, 23 (11.2%) showed negative, 94(45.6%) weakly positive, 72 (35.0%) moderately positive, and 17 (8.3%) strongly positive for EphA2 immunostaining. For EphrinA-1 protein expression, 17 tumors (8.3%) showed negative, 95 (46.1%) weakly positive, 71(34.5%) moderately positive, and 23 (11.2%) strongly positive. EphA2 and EphrinA-1 often colocalized in the same tumor areas and vascular endothelial cells. Variable amount of mRNA expressions of EphA2 and EphrinA-1 were observed in the 20 tumors analyzed. There was no significant correlation between the overexpressions of EphA2/EphrinA-1 and age and FIGO stage. High level of EphA2 was significantly associated with overall survival in univariate and multivariate analysis. Moderate to high EphrinA-1 protein expression was significantly associated with overall survival in multivariate analysis. The combined high level of expression of EhpA2 and moderate to high level of expression of EphrinA-1 was a strong predictor of overall survival. CONCLUSIONS: High levels of EphA2 together with moderate to high level of EphrinA-1 protein expressions in squamous cervical carcinoma were predictive for a shorter overall survival and these proteins may be valuable prognostic markers.

Adult↗
PubMed2004

Immobilization of Aspergillus niger tannase by microencapsulation and its kinetic characteristics.

Tannase from Aspergillus niger was microcapsulated with a coacervate calcium alginate membrane surrounding a liquid core. The activity yield was 36.8% under the optimum conditions of immobilization, namely 6 g/litre sodium alginate and 0.18 M CaCl(2). The optimum pH and temperature for free and immobilized tannase were 5.0 and 30 degrees C, and 6.0 and 40 degrees C, respectively. The pH stability, as well as thermal stability, was improved significantly after microencapsulation. K(m) values for the free and immobilized enzyme were 0.011 and 0.041 microM respectively. V(max) values changed from 416 to 131 micromol x min(-1) x mg(-1) upon immobilization. The kinetic parameters for free and immobilized tannase were also determined. The immobilized tannase was stable enough to be used for up to 15 runs. These kinetic characteristics of the immobilized tannase show more promise for industrial application than those of the free enzyme.

Alginates↗
PubMed2004

[Fast purification of human serum albumin with chromatographic pie in analytical scale].

The purification of human serum albumin (HSA) by using analytical chromatographic pie was developed. Six standard proteins were separated on an analytical chromatographic pie. The results from the resolution of the standard proteins under various flow rates indicate that the chromatographic pie in analytical scale packed with small particles can be utilized under fast flow conditions. The type of mobile phase, concentration of (NH4)2SO4 and pH value for HSA purification were optimized. Crude HSA solution was purified in 10 min in analytical scale with the purity of HSA more than 85% and recovery of 65%. The results show that analytical chromatographic pie is suitable for fast separation and purification of biopolymers.

Chromatography, High Pressure Liquid↗
PubMed2004

[Spectrophotometric determination of trace amount of lead with trimethoxyphenylfluorone in microemulsion after using sulphydryl dextran gel for preconcentration and separation].

In this paper, the color reaction of lead with trimethoxyphenylfluorone (TM-PF) in microemulsion has been studied. Lead (II) reacts with TM-PF to form a stable 1:2 complex at pH 9.1. Its apparent molar absorptivity is 5.32 x 10(4) L x mol(-1) x cm(-1) at 565 nm. Beer's law is obeyed in the range of 0-1.5 microg x mL(-1). Sulphydryl dextran gel (SDG), in which sulphydryl group has a big share, is a new type of metallic ion adsorbent. It presents the advantage of higher adsorption capacity, better reuse ability and higher mechanical stability. So the coexistent metal ions can be separated effectively and lead can be enriched by SDG, greatly improving the selectivity and sensibility of the system. The method was used to determine trace amount of lead in blood, hair and urine samples with satisfactory results.

Chromatography, Gel↗
PubMed2003

Immune response and protection elicited by DNA immunisation against Taenia cysticercosis.

The study evaluated DNA vaccination in Taenia solium cysticercosis prevention by using cDNA of an antigen (cC1) from T. solium metacestode. pcDNA3-cC1 DNA vaccine was constructed by inserting the cDNA into the eukaryotic expression plasmid pcDNA3. Positive expression of the pcDNA3-cC1 product was confirmed by its transfection into COS7 cell and enzyme-linked immunoabsorbent assay using serum of pigs infected with T. solium metacestode. Immunisation of BALB/c mice with three injections of pcDNA3-cC1 induced antigen-specific immune responses of the Th1 phenotype. Inoculation of new-born pigs induced protection against challenge with T. solium by 73.3% reduction of the metacestode number. Antibodies elicited by DNA immunisation with pcDNA3-cC1 specifically reacted with native cC1 protein, which was mainly restricted to the cyst wall of T. solium metacestode. Positive apoptosis signals were also detected in the cyst wall cells of metacestode slices from pigs immunised with pcDNA3-cC1 by TUNEL staining method. Those suggested that apoptosis played a role in protecting pigs immunised with pcDNA3-cC1 nucleic acid vaccine from pathogen challenge.

Animals↗
PubMed2003

A case report of localized gastric amyloidosis.

AIM: To elucidate the clinical and laboratory features of localized gastric amyloidosis via a rare report along with a review of related literatures. METHODS: The clinical manifestations, laboratory results and surgical treatment of a female patient with localized gastric amyloidosis in our hospital were summarized. The relevant literatures were reviewed on the etiology, clinical features, diagnosis, treatment and prognosis of this disease. RESULTS: The patient was lack of specific clinical manifestations and positive laboratory results. Prior to the treatment, she was suspected to be of malignization from gastric ulcer by both gastroscopy and endoscopic ultrasonography, which was denied by the gastric biopsy. The patient was treated with subtotal gastrectomy and clearance of perigastric lymph nodes. The postoperative pathological diagnosis determined the lesion to be the deposition of amyloid materials in the gastric mucosa, submucosa and blood vessel walls with intestinal metaplasia and atrophy of the gastric glands, in which no malignant tumor was found. Congo red staining with prior potassium permanganate incubation confirmed the AA type of amyloid in this case. Multiple biopsies from esophagus, remnant stomach, duodenum, colon and bone marrow in the follow-up survey showed no amyloidal deposition in these tissues and organs. Up to the present, no signs of recurrence have been found in this patient. CONCLUSION: Localized gastric amyloidosis, being rare in incidence, should be considered in the differentiation of gastric tumors, in which biopsy is the only means to confirm the diagnosis. Currently, surgical resection of pathological tissue and circumambient lymph nodes may be a preferable therapeutic strategy for the localized amyloidosis to prevent possible complications. Although with a benign prognosis, gastric amyloidosis possesses a recurrent tendency as suggested by the literatures.

Amyloidosis↗
PubMed2002

[BRCA2 gene mutation detection in hereditary ovarian cancer tissues].

OBJECTIVE: The aim of this study was to detect the mutation of BRCA2 gene in hereditary ovarian cancer tissues to probe the clinical significance of it. METHODS: DNA was abstract from paraffin embedded tissues archived in pathology department. A pair of primer located on 11 exon was used to detect the 6174 delT mutation,BRCA2 gene mutation in 12 hereditary ovarian cancer patients and 15 sporadic ovarian cancer patients were screened by polymerase chain reaction-single strand conformation polymorphism analysis with DNA non- isotopic silver staining methods. RESULTS: Two of 12 hereditary ovarian cancer victims were found carrying mutation of BRCA2 gene. The mutation type was 6174del T in the 11 exon of BRCA2 gene. No mutation of BRCA2 gene on this site was found in 15 sporadic ovarian cancer patients. CONCLUSION: BRCA2 gene mutation was closely associated with the carcinogenesis and development of hereditary ovarian cancer, but had no relationship with sporadic ovarian cancer.

Female↗
PubMed2002

The role of determining the levels of serum collagen type IV in diagnosing early diabetic nephropathy.

Two molecules of type IV collagen are linked via the COOH-terminal non-collagenous domain (NCI domain). In this way, type IV collagen forms the main framework of basement membrane. We have developed sandwich Enzyme-Linked Immunosorbent Assay (ELISA) for human serum type IV collage peptide monoclonals for CO5 and CO6 recognizing two different determinants on the central triplex of human collagen molecules. Using this, we explored the possibility that serum levels of type IV collagen (Col IV) are an indicator of early diabetic nephropathy (DN). Serum type IV collagen levels were determined by ELISA in 36 patients with diabetic nephropathy. Serum hemoglobin A1c (HbA1c) and in twenty-four hour urinary albumin excretion rates (UAER) were measured at the same time. A relationship was found between serum levels of this collagen IV and the presence of diabetic nephropathy. That is, serum levels of type IV collagen in diabetic nephropathy were significantly higher than those found in non-insulin-dependent diabetic (NIDDM) patients without nephropathy and in healthy subjects (HS). It is possible that an elevated serum collagen type IV level reflects increased synthetic activity in basement membrane collagen type IV. Serum type IV collagen may be a useful marker for monitoring the dynamics of basement membrane metabolism and in this way serve as a clinical indicator of the progression or the activity of diabetic nephropathy and a marker for the assessment of therapeutic effects.

Adult↗
PubMed2002

Association of genetic polymorphisms in CYP2E1, MPO, NQO1, GSTM1, and GSTT1 genes with benzene poisoning.

Metabolic enzymes involved in benzene activation or detoxification, including NAD(P)H, quinone oxidoreductase 1 (NQO1), cytochrome P450 2E1 (CYP2E1), myeloperoxidase (MPO), glutathione-S-transferase mu-1 (GSTM1), and glutathione-S-transferase theta-1 (GSTT1), were studied for their roles in human susceptibility to benzene poisoning. The potential interactions of these metabolic enzymes with lifestyle factors such as cigarette smoking and alcohol consumption were also explored. We studied 156 benzene-poisoning patients and 152 workers occupationally exposed to benzene in South China. Sequencing, denaturing HPLC, restriction fragment-length polymorphism, and polymerase chain reaction were used to detect polymorphisms on the promoters and complete coding regions of NQO1, CYP2E1, MPO, and the null genotypes of GSTM1 and GSTT1. Seventeen single nucleotide polymorphisms (SNPs) were identified in NQO1, CYP2E1, and MPO genes, including 6 novel SNPs in CYP2E1 and MPO. Of the subjects who smoked and drank alcohol, an 8.15-fold [95% confidence interval (CI), 1.43-46.50] and a 21.50-fold (95% CI, 2.79-165.79) increased risk of benzene poisoning, respectively, were observed among the subjects with two copies of NQO1 with a C-to-T substitution in cDNA at nucleotide 609 (c.609 C>T variation; i.e., NQO1 c.609 T/T) compared to those with the heterozygous or wild (NQO1 c.609 C/T and c.609 C/C) genotypes. Our data also indicated that individuals with CYP2E1 c.-1293 C/C and c.-1293 G/C, and NQO1 c.609 T/T, and GSTT1 null genotypes tended to be more susceptible to benzene toxicity. Our results suggest that the combined effect of polymorphisms in NQO1, CYP2E1, and GSTT1 genes and lifestyle factors might contribute to benzene poisoning.

Benzene↗