Biomedical subjects

X Xu

Publications and source records attributed to X Xu.

At least 379 records · Page 21Linked to original sources

PubMed2000

[The multimedia molecular biological image processing system].

With the use of computer image processing technology and molecular biological technology, we have developed a new multimedia molecular biological information processing system to detect the characteristic parameter of molecular biological electrophoresis image. The system can determine the macromolecules densities and molecular weight of the DNA amplified fragment or restriction endonuclease hydrolytic fragment protein and other macromolecules. The clinical use and biological application indicate that the system is useful to gene diagnosis and molecular biological researches.

Computational Biology↗

PubMed2000

Arsenic speciation based on ion exchange high-performance liquid chromatography hyphenated with hydride generation atomic fluorescence and on-line UV photo oxidation.

An on-line method capable of the separation of arsenic species was developed for the speciation of arsenite As(III), arsenate As(V), monomethylarsenic (MMA) and dimethylarsenic acid (DMA) in biological samples. The method is based on the combination of high-performance liquid chromatograph (HPLC) for separation, UV photo oxidation for sample digestion and hydride generation atomic fluorescence spectrometry (HGAFS) for sensitive detection. The best separation results were obtained with an anion-exchange AS11 column protected by an AG11 guard column, and gradient elution with NaH2PO4 and water as mobile phase. The on-line UV photo oxidation with 1.5% K2S2O8 in 0.2 mol L(-1) NaOH in an 8 m PTFE coil for 40 s ensures the digestion of organoarsenic compounds. Detection limits for the four species were in the range of 0.11-0.15 ng (20 microL injected). Procedures were validated by analysis of the certified reference materials GBW09103 freeze-dried human urine and the results were in good agreement with the certified values of total arsenic concentration. The method has been successfully applied to speciation studies of blood arsenic species with no need of sample pretreatment. Speciation of arsenic in blood samples collected from two patients after the ingestion of realgar-containing drug reveals slight increase of arsenite and DMA, resulting from the digestion of realgar.

Arsenates↗

PubMed2000

[Relationship between insulin resistance and pregnancy induced hypertension].

OBJECTIVE: To investigate whether insulin resistance is a cause of pregnancy induced hypertension (PIH). METHODS: All patients who had abnormal 50 g glucose screening test accepted 75 g oral glucose tolerance test (OGTT) and insulin sensitive index (ISI) was calculated. These patients were followed up and divided into two groups (PIH group and normal pregnancy group) at third trimester of pregnancy. The difference of ISI between the PIH group and normal pregnancy group was compared. RESULTS: Fast blood glucose, fast blood insulin and ISI were (4.2 +/- 0.7) mmol/L vs. (3.8 +/- 0.7) mmol/L, (107.8 +/- 48.8) pmol/L vs. (50.4 +/- 40.5) pmol/L, and -3.25 +/- 0.27 vs. -2.58 +/- 0.66 in PIH group and normal group, respectively (P < 0.05). The areas under the curve of insulin were 1,125.6 +/- 331.0 and 1,057.6 +/- 442.2 in PIH group and normal pregnancy group, respectively (P > 0.05). CONCLUSIONS: Insulin resistance during second trimester of pregnancy may be one of the causes of pregnancy induced hypertension.

Adult↗

PubMed2000

[The investigation of glucocorticoid receptor in peripheral blood mononuclear cells from patients with myasthenia gravis].

OBJECTIVE: To investigate the alteration of glucocorticoid receptor(GR) in peripheral blood mononuclear cells (PBMC) from patients with myasthenia gravis(MG) and to explore its mechanism. METHODS: 3H-dexamethansone binding assay and Scatchard analysis were used to measure the number of GR and dissociation constant in PBMC from 193 MG patients, 10 patients with other neuroimmunological disorders, 66 with cerebral vascular disorders (CVD) and 35 healthy donors. Slot blot hybridization was used to detect GRmRNA. RESULTS: GR numbers in MG patients were much lower than those in healthy controls (P < 0.01), but GR affinity between these two groups was not remarkably different (P > 0.05). GR numbers of PBMC from MG patients after culture in normal plasma were not significantly different from those before culture. No obvious change was observed in GR numbers of PBMC from healthy donors after the cells were incubated with MG plasma. GRmRNA of PBMC in MG patients was significantly lower than that in healthy donors, and was well correlated with GR numbers (r = 0.89, P < 0.01). CONCLUSION: GR numbers are low in MG patients. The decrease of GR numbers may be related to the decrease of GRmRNA transcription.

Adolescent↗

PubMed2000

[Research of status of provirus HIV DNA in non-progressor and progressor of HIV-1 infected persons].

OBJECTIVE: This study was designed to investigate the different status of provirus HIV DNA in non-progressor and progressor of HIV-1 infected persons. METHODS: HIV RNA, HIV DNA were detected with long-distance PCR (LD-PCR), reverse transcription PCR (RT-PCR), Southern blot and molecular hybridization from plasma and peripheral blood mononuclear cells (PBMCs), using primers locating between long terminal repeats LTR(U5)-LTR(R) and so on. RESULTS: 9.1 kb band is full-length HIV DNA genome which was present in all templates of 12 progressors. Deleted HIV DNA was observed in 9 of 12 progressors. Both the full-length and defective. provirus HIV DNA was detected in 5 of the 18 non-progressors. Defective HIV DNA was only detected in the other non-progressors. CONCLUSIONS: Clinical stages are closely related with both the full-length and the defective HIV DNA.

DNA Primers↗

PubMed2000

Co-modification of IL-2-TNF alpha fusion gene and B7.1 gene to murine breast tumor cells leads to improved tumor rejection and vaccine effect.

OBJECTIVE: To improve the vaccine potency of gene-modified tumor cells. METHODS: Using recombinant adenoviruses, we expressed the B7.1 gene in murine breast tumor cell line EMF6 and a subline previously transfected with retrovirus vector XdF harboring the IL-2-TNF alpha fusion gene. RESULTS: Immunization/challenge experiments demonstrated that IL-2-TNF alpha/B7.1 co-modified tumor cells possessed a lower tumorigenicity in vivo and an improved tumor-specific vaccine potency compared with single gene transfectant (P < 0.05). Three weeks after immunization with a variety of tumor cells, the mixed lymphocyte and tumor cells reaction assay (MLTB) and 51Cr-release assay were performed to test cellular immunity function. The results indicated that IL-2-TNF alpha and B7.1 together induced a more potent antitumor immune response than either molecule alone, 25% higher than IL-2-TNF alpha and 20% higher than B7.1, respectively. CONCLUSION: The IL-2-TNF alpha fusion gene and B7.1 gene act in concert to improve their antitumor effectiveness.

Animals↗

PubMed2000

[Expression of major histocompatibility complex-class I antigen on endometrial stroma cells in patients with endometriosis].

OBJECTIVE: To study the possible effect of major histocompatibility complex-class I (MHC-I) antigen on endometrial stromal cells in endometriosis patients. METHODS: The stromal cells of endometrium was separated and cultured in vitro. gamma-interferon (gamma-IFN) was added to modulate the MHC-I antigen level which was assessed by flowcytometry, and the sensitivity of endometrial stromal cells to cytotoxic lymphocytes was examined by methyl thiazolyl tetrazolium (MTT). RESULTS: Our study demonstrated that in vitro cultured stromal cells with significant reduced MHC-I antigen levels showed enhanced susceptibility to lysis (51.28%) mediated by lymphokine-activated killer (LAK) cells, whereas gamma-IFN treated in vitro cultured stromal cells with restored MHC-I antigen levels showed more resistance to lysis (28.64%). CONCLUSIONS: MHC-I antigen on endometrial stromal cells may inhibit the cytotoxicity of natural killer (NK) cells and NK-like T cells, which might play a key role in the pathogenesis of endometriosis. The level of MHC-I antigen could be regulated by culture or some biologic factors such as gamma-IFN.

Cells, Cultured↗

PubMed2000

p53 mutation, EGFR gene amplification and loss of heterozygosity on chromosome 10, 17 p in human gliomas.

OBJECTIVE: To further illustrate the roles of p53 gene, epidermal growth factor receptor (EGFR) gene and loss of heterozygosity (LOH) on chromosome 10 and 17 p in human glioma progression. METHODS: p53 mutations were scanned in 50 gliomas with various malignant grades using the polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) assay, and were confirmed by direct sequencing. LOH for chromosome 10, 17 p and amplification of the EGFR gene were also assessed using Southern blot analysis. RESULTS: p53 mutations were found in 9 of 17 high-grade astrocytomas (53%), 1 of 15 low-grade astrocytomas (7%), and the only subject of eppendymoblastoma but in none of the 10 medulloblastomas and 7 eppendymomas. The majority of gliomas (38/50) analyzed here retained both 17 p alleles. The frequency of p53 mutations was 13% in this group of tumors and increased to 50% (6/12) in tumors with one 17 p allele (P < 0.025). LOH on chromosome 10 was found in 35% (6/17) of high-grade astrocytomas, in 10% (1/10) of medulloblastomas, but in 0% of low-grade gliomas. EGFR gene amplification was found in 9 high-grade gliomas, 60% (6/9) of which also presented LOH for chromosome 10. CONCLUSIONS: These results indicate that p53 inactivation is a common genetic event in astrocytoma progression that may be more strongly associated with the progression of astrocytomas than with their origin. Absence of p53 mutations in 50% of the tumors with one 17 p allele suggests that a tumor suppressor gene other than p53 may be located on chromosome 17 p and involved in progression to malignancy of some gliomas. The loss of alleles on chromosome 10 and the amplification of the EGFR gene appear to be restricted to high-grade tumors, suggesting that these events may be related to tumor progression rather than initiation.

Brain Neoplasms↗

PubMed2000

[A preliminary study of laser Doppler technique in determining dental pulpal blood flow].

OBJECTIVE: To investigate the possibility of using laser Doppler flowmetry to study dental pulpal blood flow. METHODS: The pulpal blood flow of 80 healthy maxillary incisors of 20 volunteers and 15 teeth with necrotic pulp of 11 patients were determined by JI-200 Laser Doppler Flowmetry. The pulpal blood flow of 16 teeth with deep caries were measured before and after treatment. RESULTS: There were no obvious difference of the pulpal blood flow values between the right and the left part, neither the male and the female. Maxillary central incisors had a slightly greater pulpal blood flow values than maxillary lateral incisors. The flow values from 15 teeth with necrotic pulp or pulpless teeth were significantly lower than that from the control teeth. Before therapy the values from 16 deep caries teeth were all higher than that from the control teeth. After therapy, most (15/16) of those values decreased to normal in three days. The value of one tooth with deep caries remained high, and one week later, the pulp became necrosis. CONCLUSION: Laser Doppler flowmetry has great potentialities in the study of pulp blood flow, and deserves more concerns.

Adult↗

PubMed2000

[Influence of multiple coats of bonding agent on the bond strength of amalgam bonding].

OBJECTIVE: To evaluate the effect of multiple coats of bond on the bond strength of amalgam bonding. METHODS: One or two layers of Scotch-bond multi-purpose plus dental adhesive agent were applied on the dental walls of two groups of teeth respectively prior to amalgam condensation. The third group was set for control which only had amalgam filling. After one week, thermocycling, shear bond strength were tested for all specimens with 1195-Instron testing machine. Data were analyzed by SPSS 8.0. The SEM observation were made in other five modals with one or two layers bonding. RESULTS: The shear strengths of two or one layer bond and control one were 25.77, 20.69 and 13.05 MPa separately. The difference among them was statistical significant (P < 0.01). CONCLUSIONS: The microlocking was more obvious in specimens of two bonding layers.

Biomechanical Phenomena↗

PubMed2000

[Iodine-125 labeled monoclonal antibody 3H11: in radioimmunoguided surgery for primary gastric cancer].

OBJECTIVE: To evaluate the clinical usefulness of iodine-125 labeled monoclonal antibody (MAb) 3H11 in radioimmunoguided surgery (RIGS) for patients with gastric cancer. METHODS: Thirty-five patients with primary gastric cancer were enrolled. Via endoscopy, iodine-125 labeled MAb 3H11 was injected into submucosa around the tumor. All patients underwent surgery 4 to 11 days after administration. Intraoperative radioimmunodetection was performed using a hand-held gamma-detecting probe. The counts of target sites were obtained, and tumor-to-normal tissue (T/NT) ratios were calculated. The T/NT ratio of 3.5:1 was taken as the lowest threshold value of positive gastric wall infiltration, and 3.0:1 for lymph node metastasis. Serial sections of those RIGS-positive lymph nodes, which were originally diagnosed as negative by routine histology, were made. Immunohistochemical staining was performed to detect the existence of lymphatic micrometastasis. RESULTS: Of thirty-five patients, 33 underwent RIGS successfully. The accuracy rate in detecting tumor infiltration of the incision margins was 97.0%, and the specificity 98.5%. In the group of patients with an interval of 6 to 8 days between injection and operation (n = 25), the RIGS results were satisfying. For the detection of lymphatic metastasis, the sensitivity of RIGS was 83.6%, the specificity 95.0%, and the accuracy 91.3%. The existence of lymphatic micrometastasis were verified immunohistochemically in 52.6% (10/19) of those RIGS positive but histologically negative lymph nodes. CONCLUSION: This study validates the use of iodine-125 labeled monoclonal antibody 3H11 for the intraoperative detection of carcinomatous lesions in gastric cancer.

Adult↗

PubMed2000

[Electron-immunostaining characteristics of platelet-derived growth factor, transforming growth factor beta1 and their receptors in epiretinal membranes].

OBJECTIVE: To investigate the ultrastructural distribution of platelet-derived growth factor (PDGF), transforming growth factor beta(1) (TGF-beta(1)) and their receptors in epiretinal membranes (ERM) and discuss the clinical significance of the distribution. METHODS: 25 membrane specimens were surgically removed by vitrectomy from 9 patients with rhegmatogenous retinal detachment. Double-staining techniques of immunoelectromicroscopy for eight antibodies (PDGF, TGF-beta(1), PDGF receptor subunits alpha and beta, TGF-beta subunits I and II, type I and III collagen) were used in these specimens as previously designed. RESULTS: PDGF and TGF-beta(1) staining appeared to be stronger on early (< 2 months) and late (> 6 months) stage membranes than that of middle (2 - 6 months) stage of membranes, and the immunostaining intensity inverted with the degree of proliferative vitreoretinopathy (PVR). We found that the gold particles of PDGF and TGF-beta(1) tended to get together with that of type I and III collagen. In addition, the stainings of four growth factor receptors were frequently positive in a type of epithelial-like cells with rich cytoplasm components, and also the gold particles of PDGF and TGF-beta(1) were found around these cells. CONCLUSIONS: A concentration change of PDGF and TGF-beta(1) exists in development of ERM throughout. The epithelial-like cells are of a type of active cells, and autocrine and paracrine activity may be involved in ERM pathogenesis. PDGF and TGF-beta(1) influence the contractile activity of ERM.

Epiretinal Membrane↗

PubMed2000

[Analysis on Helicobacter pylori infection and its related diseases in 1,442 children in Tianjin city].

OBJECTIVE: The aim of this study was to investigate the prevalence of Helicobacter pylori (Hp) infection in children in Tianjin and to study the relationship between the Hp infection and its related diseases. METHODS: (1) Serologic examination for Hp - IgG; (2) Rapid urease test for Hp (Hp - Rut); (3) Giemsa staining for Hp; (4) Gastric fluid examination for Hp by PCR. Hp infection were diagnosed by at least two criteria. RESULTS: (1) Of the 1 442 children, 651 were Hp - IgG positive. The total positive rate was 45.15%, Positive rates of Hp - IgG among children under the age of 1 year, 3 years, 6 years, 10 years and to 14 years were 11.19%, 19.23%, 44.21%, 54.20% and 61.46%, respectively. (2) Positive rates of Hp - IgG were 31.18% (164/526) and 53.17% (48/916) in asymptomatic children and in patients with gastrointestinal symptoms. The rate was significantly higher in the later group (P < 0.005). (3) Hp infection rate in patients with duodenal ulcer (DU) was 90.76%, higher than that in other gastrointestinal diseases. (4) Histological examination showed that Hp infection rates were 33.20% and 83.97% in mild and moderate or severe gastritis, respectively. CONCLUSIONS: (1) The prevalence of Hp infection in children in Tianjin was high. (2) Rate of Hp infection increased with age and Hp infection rate was higher in children with gastrointestinal symptoms than with asymptomatie. (3) There was a high correlation in children with gastroduodenal diseases and Hp infection especially with DU. (4) Hp positive rate correlated with the pathohistologic severity of gastritis.

Adolescent↗

PubMed2000

[A case-control study on the risk factors of epidemic hemorrhagic fever].

OBJECTIVE: To study the risk factors of epidemic hemorrhagic fever (EHF). METHODS: A 1:1 matched case-control study was conducted to analyse EHF risk factors. RESULTS: One hundred and eighty-five matched pairs were investigated. Five factors were associated with risks of the disease, including rodent activity in house, farm working, travel, annual average income of an individual and ground material of the house, when chi(2) test and logistic regression model were processed respectively. The coefficients of rodent activity in house, farm working, travel, annual average income of an individual and ground material of the house in multivariable Logistic regression model were 1.377, 1.687, 1.630, -1.216 and -0.888, respectively, when P value < 0.05 was observed. CONCLUSIONS: Factors as high average income of individuals, brick or cement used as material of the ground in the house, seemed to be protective factors of EHF, which were important to the control and prevention of EHF.

Adult↗

PubMed2000

[Safety and immunogenicity of inactivated bivalent EHF vaccine in humans].

OBJECTIVE: Safety and immunogenicity of inactivated bivalent EHF vaccine in humans were evaluated in the epidemic area of Zhejiang province, China. METHODS: Susceptible persons with negative anti-EHF were selected in Jiande county, Zhejiang province to receive 3 doses of inactivated bivalent EHF vaccine at 0, 7, 28 days. A booster injection was given one year after the primary immunization. Antibody responses were measured in human volunteers by IFA and MCPENT. Local and general reactions were recorded within 72 hours after each vaccination by physicians. RESULTS: Two weeks after the primary vaccination, 99.04% of the subjects developed significant hantavirus antibody titre measured by IFA which had a 37.34% drop one year after the primary vaccination. Seroconversion rate increased to 100% two weeks after the booster dose. Neutralising antibody titres paralleled this trend with 100% of vaccine recipients producing neutralising antibody two weeks after the primary doses. However, it dropped to 80% one year after the primary vaccination. One hundred percent of the vaccine recipients started to respond two weeks after boosting. The geometric mean titre (GMT) of neutralising antibody against 76 - 118 and UR were 18.27 +/- 2.21 and 12.47 +/- 2.16 respectively after the primary injections, but it increased to 37.09 +/- 2.24 and 32.61 +/- 2.05 respectively after the secondary immunization. General and local reaction rates were 0.46% and 1.98%, with no severe side effects observed in the vaccinees. CONCLUSION: The vaccine was well tolerated and could induce good humoral immune response.

Antibodies, Viral↗

PubMed2000

[Cost-effectiveness analysis of Beijing Fangshan cardiovascular prevention program in 1992 - 1997].

OBJECTIVE: To determine whether a community-based cardiovascular disease (CVD) intervention program, undertaken over six years, was cost-effective. METHODS: Based on Beijing Fangshan Cardiovascular Disease Comprehensive Prevention Program, the cost for intervention and expenditure saved from caring for CVD in the communities with intervention from 1992 to 1997 were calculated, and cost-effectiveness analysis was performed using disability-adjusted life years (DALYs) gained as an indicator of effectiveness. RESULTS: The cost for one DALY gained reduced gradually from 1992 to 1997, with an average ratio of cost to effectiveness of four to one (4:1). It cost annually 1,586.00, 1,380.20, -2,350.80, -905.30, -1,495.60 and -1,766.70 RMB yuan for one life-year saved, from 1992 to 1997 respectively, in a gradually decreasing trend with the increase in length of intervention. After intervention for two years, ratio of cost to effectiveness has become negative since 1994, which meant a positive benefit from intervention. Sensitivity analysis showed that ratio of cost to effectiveness was little sensitive to the changes in discount rate, weight of age and increase in cost of hospitalization for stroke and coronary heart disease, which reflected its reliability. CONCLUSION: Community-based comprehensive intervention for CVD in rural population is cost-effective.

Aged↗

PubMed2000

[Pathological study of the pleomorphic carcinoma of the lung].

OBJECTIVE: A clinicopathological study of 10 patients with pleomorphic carcinoma of the lung. METHODS: Histopathological and immunohistochemical staining for keratin, vimentin, Mac387, desmin, actin and S-100 protein were used for this study. RESULTS: Pleomorphic carcinoma of the lung was found to often occur in males above 50 years of age and with clinical symptoms including cough, expectoration, haemoptysis and chest pain. The most frequent microscopic diagnosis was squamous cell carcinoma, and adenocarcinoma, accompanied by spindle and giant cells. The epithelial component of pleomorphic carcinoma of the lung displayed positivity for keratin and the spindle cells displayed positivity for vimentin. In some cases the neoplastic epithelial component and spindle cells showed positive expression of both keratin and vimentin. CONCLUSION: Pleomorphic carcinoma of the lung may display various histopathological changes making it easy to be misdiagnosed as carcinosarcoma. Understanding its pathogenesis and histopathology is important for the diagnosis and differential diagnosis.

Adenocarcinoma↗

PubMed2000

[Distribution of minimal residual leukemia in Brown Norway rats express LacZ gene].

OBJECTIVE: To investigate the distribution of minimal residual leukemia (MRL) in vivo. METHODS: The MRL model in BN rat was established by using LT12nl leukemia cell line carrying LacZ gene. The marker gene (LacZ) was detected by using reverse transcriptase polymerase chain reaction (RT-PCR) and nested PCR, X-gal staining, and cytomorphological and pathological examination. RESULTS: PCR assays showed positive result in humerus at day 4, femur at day 6, and spleen at day 9 after CTX treatment. The peak positive signal in humerus was stronger at day 9. X-gal staining showed negative in spleen at day 9. PCR showed negative results in peripheral blood and liver. CONCLUSION: PCR can be used as an effective tool to investigate the distribution pattern in experimental MRL.

Animals↗