Biomedical subjects

Lin Zhang

Publications and source records attributed to Lin Zhang.

At least 91 records · Page 5Linked to original sources

PubMed2006

Free fatty acids inhibit insulin signaling-stimulated endothelial nitric oxide synthase activation through upregulating PTEN or inhibiting Akt kinase.

In metabolic syndrome, a systemic deregulation of the insulin pathway leads to a combined deregulation of insulin-regulated metabolism and cardiovascular functions. Free fatty acids (FFAs), which are increased in metabolic syndrome, inhibit insulin signaling and induce metabolic insulin resistance. This study was designed to examine FFAs' effects on vascular insulin signaling and endothelial nitric oxide (NO) synthase (eNOS) activation in endothelial cells. We showed that FFAs inhibited insulin signaling and eNOS activation through different mechanisms. While linoleic acid inhibited Akt-mediated eNOS phosphorylation, palmitic acid appeared to affect the upstream signaling. Upregulation of PTEN (phosphatase and tensin homolog deleted on chromosome 10) activity and transcription by palmitic acid mediated the inhibitory effects on insulin signaling. We further found that activated stress signaling p38, but not Jun NH(2)-terminal kinase, was involved in PTEN upregulation. The p38 target transcriptional factor activating transcription factor (ATF)-2 bound to the PTEN promoter, which was increased by palmitic acid treatment. In summary, both palmitic acid and linoleic acid exert inhibitory effect on insulin signaling and eNOS activation in endothelial cells. Palmitic acid inhibits insulin signaling by promoting PTEN activity and its transcription through p38 and its downstream transcription factor ATF-2. Our findings suggest that FFA-mediated inhibition of vascular insulin signaling and eNOS activation may contribute to cardiovascular diseases in metabolic syndrome.

Activating Transcription Factor 2↗

PubMed2006

Involvement of endothelial CD44 during in vivo angiogenesis.

CD44, a cell-surface receptor for hyaluronan, has been implicated in endothelial cell functions, but its role in the formation of blood vessels in vivo has not been established. In CD44-null mice, vascularization of Matrigel implants and tumor and wound angiogenesis were inhibited. Leukocyte accumulation during tumor growth and wound healing in wild-type and CD44-null mice were comparable, and reconstitution of CD44-null mice with wild-type bone marrow did not restore the wild-type phenotype, suggesting that impairments in angiogenesis in CD44-deficient mice are due to the loss of endothelial CD44. Although the cell proliferation, survival, and wound-induced migration of CD44-null endothelial cells were intact, these cells were impaired in their in vitro ability to form tubes. Nascent vessels in Matrigel implants from CD44-null mice demonstrated irregular luminal surfaces characterized by retracted cells and thinned endothelia. Further, an anti-CD44 antibody that disrupted in vitro tube formation induced hemorrhage around Matrigel implants, suggesting that antagonism of endothelial CD44 undermined the integrity of the endothelium of nascent vessels. These data establish a role for CD44 during in vivo angiogenesis and suggest that CD44 may contribute to the organization and/or stability of developing endothelial tubular networks.

Animals↗

PubMed2006

Prognostic value of apoptosis-associated speck-like protein containing a CARD gene promoter methylation in resectable non-small-cell lung cancer.

BACKGROUND: The apoptosis-associated speck-like protein containing a CARD (ASC) is a newly identified tumor suppressor gene that is frequently inactivated by de novo promoter methylation in non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS: We studied 79 patients with NSCLC who had undergone surgery with curative intent. The ASC promoter methylation status was determined by methylation-specific polymerase chain reaction. Statistical analyses (all 2-sided) were performed to determine the prognostic effect of hypermethylation on various clinical parameters. RESULTS: ASC promoter hypermethylation was detectable by methylation-specific polymerase chain reaction in 9 of 70 (12.9%) normal lungs and in 33 of 70 (47.1%) matching tumor samples of patients with NSCLC. The mean ASC methylation level was significantly higher in tumor than in matching normal tissue (P < 0.001). ASC methylation in normal tissue was always accompanied with ASC methylation in matching tumor tissue. Patients without ASC promoter hypermethylation showed a significantly better survival than patients with ASC promoter hypermethylation (P = 0.007). Multivariate analysis revealed ASC promoter methylation as an independent unfavorable prognostic factor (P = 0.009). CONCLUSION: Our results indicate that ASC promoter hypermethylation is a common event in patients with primary NSCLC, and this epigenetic alteration is associated with inferior survival, suggesting that ASC promoter hypermethylation might be an important biomarker for a biologic, aggressive disease in NSCLC.

Adult↗

PubMed2006

Identification and classification in le fort type fractures by using 2D and 3D computed tomography.

OBJECTIVE: To evaluate the usefulness of two- dimensional (2D) and three-dimensional (3D) computed tomography (CT) in the identification and classification of Le Fort type fractures. METHODS: Sixty-two patients with different types of Le Fort fractures underwent CT scanning and 3D-CT reconstruction. The data were analyzed by multiplanar reconstruction (MPR), surface shaded display (SSD) and volume rendering (VR) respectively. RESULTS: The patients with Le Fort I, Le Fort II fracture and Le Fort III fracture accounted for 16.1%, 14.5% and 12.9% respectively. The compound fractures were the most common type and accounted for 56.5% (n=35, 18 cases with Le Fort I+II fracture, 10 cases with Le Fort II+III fracture and 7 cases with Le Fort I+ II+III fracture). Fifty-five cases coexisted with other fractures in maxillofacial region. 2D-CT could be used to define the tiny fractures and the deep-structure fractures more accurately compared with 3D-CT, but the real impression of Le Fort type fractures could not be correctly evaluated on 2D-CT. 3D-CT could clearly demonstrate the whole shape of Le Fort type fractures and identify the classification of Le Fort fractures. CONCLUSIONS: 3D-CT is the best imaging method for the diagnosis of Le Fort type fractures and can provide valuable information of space relationship, especially for the design of treatment plan before operation.

Adolescent↗

PubMed2006

[Analysis of the multi-amplified 5 STR loci and their allelic distribution in both Han populations in Chengdu City and Yunnan province].

OBJECTIVE: To illuminate the multi-amplified 5 STR loci and their allelic distribution in Hans by means of STR-DNA typing with improved efficiency and decreased cost. METHODS: We have established an allelic ladder of D7S820, D13S317, D5S818, D3S1358 and Amelogenin loci via the cloning techniques. With this homemade allelic ladder, we established successfully a multiplexing polymerase chain reaction (PCR) method, followed by denaturing polyacrylamide gel electrophoresis (PAGE) and silver staining. DNA samples collected from 130 unrelated Han individuals in Yunnan and Chengdu were analyzed. The non-overlapping of the allelic fragments of the five loci allowed the detection to be accomplished successfully. RESULTS: No difference of the genotyping results of the single locus amplification and multiplexing was observed. The genotype distributions of 4 STR were in accordance with the Hardy-Weinberg equilibrium. 7, 7, 8 and 8 alleles of D7S820, D13S317, D5S818, and D3S1358 loci were observed in Yunnan Han population, as well as 8, 7, 8 and 7 alleles in Chengdu Han population respectively. No significant difference in the allele distribution of these loci was seen between these two Han populations. CONCLUSION: This multiplexing system with home-made allelic ladder has a high combined discrimination power and exclusion power. It is a valuable tool in forensic science practice.

Alleles↗

PubMed2006

[Correlation between immunochemical level and patient with caries].

OBJECTIVE: To explore the relationship between immunochemical level of salivary and caries in children aged 4-6 years old. METHODS: Two groups were assorted as patients with caries and without caries. Every group included 45 people. Measurements of salivary secretory immunoglobulin A (SIgA)were performed by using radio-immunoassay and single agar diffusion assay. The levels of lysozyme (LZ), alkaline phosphatase (ALP) and lactic dehydrogenase (LDH) were studied with colorimetry and turbidimentry. RESULTS: The levels of LDH, SigA, ALP, LZ had significant difference between the two groups (P < 0.05). The level of LDH between patients and peoples without caries had little difference (P > 0.05). CONCLUSION: The incidence of caries is associated with age, and it may have association with immunochemical levels of salivary.

Alkaline Phosphatase↗

PubMed2006

[Genetic polymorphisms of three loci and implication to forensic medicine].

OBJECTIVE: To obtain population genetic data of short tandem repeat (STR) locus D2S1327, D1S1390, and D11S2008 and to investigate the disparity of allelic frequency distributions among populations from different regions. METHODS: Blood samples of 300 unrelated individuals from Chengdu (Han), Bangkok (Thai) and Maint (Germany) were taken and analyzed with single PCR, polyacrylamide gel electrophoresis and silver staining. RESULTS: In the three loci, 9, 6, and 8 alleles and 32,14, and 22 genotypes were found respectively. The observed heterozygosity of 79%-82%, 63.0%-74.3%, and 72.0%-74.3% and discrimination power of 87.8%-92.6%, 79.6%-82.5%, and 87.6%-89.0% were identified for the three loci respectively. The genotype distributions of the three loci in the three populations fitted well with Hardy-Weinberg equilibrium. There was no significant difference in allelic frequency distributions among the three populations. CONCLUSION: The methods described in this paper are easy to perform and have high sensitivities. The discrimination power and exclusion chances of these three loci are desirable for forensic analysis and application.

China↗

PubMed2006

[Production and identification of monoclonal antibody against N terminal of AIB1].

OBJECTIVE: To make and identify the monoclonal antibody against AIB1-N. METHODS: BALB/c mice were immunized with purified GST-AIB1-N protein, McAb against AIB1-N was produced by hybridoma technique. ELISA and Western-blot were used to identify the immunoglobin subtype and specificity. Results A hybridoma cell was successfully produced to secrete the McAb against AIB1-N, which was identified to belong in IgG1 subtype. By western-blot, the McAb against AIB1 displayed strongly specificity and high affinity. CONCLUSION: The McAb against AIB1 protein may be a useful tool for studying the biological properties of AIB1 expression and the clinical laboratory detection.

Animals↗

PubMed2006

[The effect of siRNA-Her2/neu on the drug sensitivity of Her2/neu-overexpressing lung adenocarcinoma cell line].

OBJECTIVE: To explore the effect of synthesized siRNA targeting Her2/neu oncogene on the drug sensitivity of Her2/neu-overexpressing lung adenocarcinoma cell line. METHODS: The experiments consisted of four groups including an untreated control group, an empty vector group, an unrelated siRNA group, and a Her2/neu siRNA group. Every experiment was repeated five times. Lung adenocarcinoma cell line Calu-3 was transfected with siRNAs formulated LipofectAMINE 2000, and Her2/neu protein and P-gp of each group were determined by flow cytometry (FCM). The chemosensitivity of transfected cells to cisplatin (DDP) was measured by MTT. Cell apoptosis detection kit (Annexin V method) was used to examine the drug induced apoptosis rate. RESULTS: The Her2/neu protein and P-gp positive expression rate in the Her2/neu siRNA group, the untreated control group, the empty vector group and the unrelated siRNA group were [(25.04 +/- 1.56)%, (4.24 +/- 1.01)%], [(98.24 +/- 2.23)%, (5.11 +/- 2.98)%], [(95.67 +/- 1.98)%, (6.98 +/- 2.47)%] or [(94.79 +/- 0.87)%, (5.59 +/- 3.66)%], respectively. Introduction of the sequence specific siRNA into Her2/neu positive Calu-3 cells in vitro greatly reduced the cell surface expression of the Her2/neu protein, but had no effect on P-gp level. Consequently the inhibitory rate of DDP in combination with siRNA targeting Her2/neu was (67.1 +/- 2.3)%, but it was (48.1 +/- 3.5)%, (46.3 +/- 5.9)% and (50.2 +/- 2.9)% in the untreated control, the empty vector and the unrelated siRNA groups, respectively. There was a significant difference between Her2/neu siRNA group and other three groups (P < 0.01). The FCM results showed the apoptosis rate of DDP combined with siRNA-Her2/neu was elevated as compared with the unrelated siRNA group, the empty vector group or the untreated control group. CONCLUSION: Sequence specific siRNA-Her2/neu was capable of enhancing the chemosensitivity of Calu-3 cells to cisplatin.

Adenocarcinoma↗

PubMed2006

[Study of the construction and function of an eukaryotic expression plasmid of immunotoxin DT390 gene].

AIM: To construct a new recombinant eukaryotic expression plasmid of murine IFN-gamma-inducible protein 10 (mIP10) gene and a truncated diphtheria toxin (DT390) gene and investigate its biological function. METHODS: mIP10 cDNA was cloned from murine liver tissue by RT-PCR and was inserted into eukaryotic expression plasmid SRalpha containing DT390 gene to construct plasmid SRalpha-DT390-mIP10. After being identified with restriction endonucleases digestion analysis and DNA sequencing, the recombinant plasmid was transfected into NIH3T3 cells through PolyFect. The expression of recombinant plasmid was detected by immunofluorescence assay and the bioactivity of mIP10-DT390 in cultured supernatant of the transfected NIH3T3 cells was detected by MTT colorimetry. RESULTS: A new recombinant immunotoxin expression plasmid SRalpha-DT390-mIP10 was constructed successfully and was expressed in NIH3T3 cells. The expressed DT390-mIP10 killed the activated T cells effectively. CONCLUSION: A new recombinant eukaryotic expression plasmid SRalpha-DT390-mIP10 has been constructed and expressed successfully, which is useful in further studying the treatment of cancer and autoimmune diseases.

Animals↗

PubMed2006

[Synergistic disinfection of Bacillus subtilis spores by UV irradiation and chlorine].

The inactivation effect of Bacillus subtilis spores was studied, both UV irradiation and chlorine disinfection individual and combined application process was examined with laboratory water samples. Results show that only 0.53 lg reduction was achieved by chlorine with CT value of 300 (mg x min)/L, UV irradiation is more effective than that of chlorination, at a UV dose of 40mJ/cm2 results in 3.3 lg reduction. Up to 6.2 lg reduction are achieved with a UV dose of 40mJ/cm2 following by chlorine with CT value of 300 (mg x min)/L. The calculation from the Berenbaum formula verified that the effect of the combined applications of UV irradiation and chlorine in inactivatiing Bacillus subtilis is a kind of synergistic effect.

Bacillus subtilis↗

PubMed2006

Screening and evaluation of human single-chain fragment variable antibody against hepatitis B virus surface antigen.

BACKGROUND: Phage display technology has become a vital tool in studies aimed at identifying molecules binding to a specific target. It enables the rapid generation and selection of high affinity, fully human antibody product candidates to essentially any disease target appropriate for antibody therapy. In this study, we prepared the recombinant single-chain fragment variable (ScFv) antibody to hepatitis B virus surface antigen (HBsAg) by the phage display technology for obtaining a virus-targeting mediator. METHODS: mRNA was isolated from B-lymphocytes from a healthy volunteer and converted into cDNA. The fragment variables of heavy and light chain were amplified separately and assembled into ScFv DNA with a specially constructed DNA linker by polymerase chain reaction. The ScFv DNA was ligated into the phagmid vector pCANTAB5E and the ligated sample was transformed into competent E.coli TG1. The transformed cells were infected with M13K07 helper phage to form a human recombinant phage antibody library. The volume and recombinant rate of the library were evaluated by bacterial colony count and restriction analysis. After two rounds of panning with HBsAg, the phage clones displaying ScFv of the antibody were selected by enzyme-linked immunosorbant assay (ELISA) from the enriched phage clones. The antigen binding affinity of the positive clone was detected by competition ELISA. HB2151 E.coli was transfected with the positive phage clone demonstrated by competition ELISA for production of a soluble form of the anti-HBsAg ScFv. ELISA assay was used to detect the antigen binding affinity of the soluble anti-HBsAg ScFv. Finally, the relative molecular mass of soluble anti-HBsAg ScFv was measured by SDS-PAGE. RESULTS: The variable heavy (VH) and variable light (VL) and ScFv DNAs were about 340 bp, 320 bp and 750 bp, respectively. The volume of the library was up to 2 x 10(6) and 8 of 10 random clones were recombinants. Two phage clones could strongly compete with the original HBsAb for binding to HBsAg. Within 2 strong positive phage clones, the soluble anti-HBsAg ScFv from one clone was found to have the binding activity with HBsAg. SDS-PAGE showed that the relative molecular weight of soluble anti-HBsAg ScFv was 32 kDa. CONCLUSION: The anti-HBsAg ScFv successfully produced by phage antibody technology may be useful for broadening the scope of application of the antibody.

Antibodies, Monoclonal↗

PubMed2006

[Screening the hALR-interacting protein from the cDNA library of hepatocarcinoma cells and studying its biological functions].

OBJECTIVES: To screen the hALR-interacting protein by phage-displayed technique and identify its biological activities. METHODS: The specific phage clones that interacted with target protein hALR from a cDNA library of hepatocarcinoma cells were selected using the T7 phage-displayed technique. The acquired cDNA inserts were sequenced and analyzed by bioinformatic tools. The biological activities of the phage-displayed peptide affecting QGY hepatocarcinoma cells were studied using 3H-TdR method. RESULTS: The cDNA inserts with 212 bp were acquired after 4 rounds of biopanning. They showed 100% homology with citron kinase. The phage-displayed peptide and the peptide combined with hALR affected QGY cells proliferation. CONCLUSIONS: hALR-interacting peptide can be specifically screened by phage-displayed technique. Citron kinase that interacted with hALR potentially plays an important role in the proliferation of hepatocarcinoma cells.

Carcinoma, Hepatocellular↗

PubMed2006

[Evaluation of the ultrasonographic features of axillary lymph node metastasis in breast cancer].

OBJECTIVE: To analyze the ultrasonographic features of axillary lymph node metastasis in breast cancer patients, and to evaluate the accuracy of these features by Receiver Operating Characteristic (ROC) curve. METHODS: Ultrasonography was carried out in 113 patients (mean age 56.5 yr, range 29 - 77 yr). The ultrasonographic features of the primary tumor and the axillary lymph node were observed. Univariate analysis was performed by Chi-squared test and Fisher exact test, and multivariate analysis to determine independent significant individual variables by multiple logistic regression analysis. ROC curve analysis was done to determine the sensitivity and specificity of individual and combined ultrasonographic features in distinguishing metastatic lymph node from the normal one. RESULTS: The primary tumor size, abundance of blood supply in the primary tumor, longitudinal-transverse diameter ratio, cortex-hilum thickness ratio (on the longitudinal section), abnormal cortex thickness, distribution of intra-nodal vascularity of axillary lymph nodes were found to be statistically significant factors by univariate analysis. The primary tumor size, longitudinal-transverse ratio and cortex-hilum thickness ratio of lymph node were proved to be significant independent predictors of axillary lymph node metastasis by logistic regression analysis. Through ROC analysis, the combination of these independent ultrasonographic feature predictors was found to contribute significantly in differentiating metastatic lymph node from the normal with a sensitivity of 88.6% and specificity of 84.5%. CONCLUSION: Axillary ultrasonography is helpful in staging the axillary lymph node in breast cancer patient. The primary tumor size, longitudinal-transverse diameter ratio and cortex-hilum thickness ratio of lymph node are the main features to determine whether metastatic involvement is present or not.

Adult↗

PubMed2006

[Correlation between desmin gene, platelet-activating factor acetylhydrolase gene and dilated cardiomyopathy].

OBJECTIVE: To test the Missense mutation of Desmin gene (Ile451Met), the frequency of missense mutation (G994-->T) of Platelet-Activating Factor Acetylhydrolase (PAF-AH) gene, and the correlation between these mutations and dilated cardiomyopathy (DCM) in the Chinese population with DCM. METHODS: A case control study was conducted with 89 DCM patients and 110 healthy people (control group) participating in the study. The exon 8 of Desmin gene and exon 9 of PAF-AH gene were identified by polymerase chain reaction, restriction enzyme digestion, polyacrylamide gel electrophoresis and DNA sequencing for described mutation site of Desmin (Ile451Met) and PAF-AH (Val279Phe). RESULTS: No mutation (Ile451Met) in Desmin gene was found in either the DCM patients or the healthy people. There was no significant difference in the frequency of PAF-AH gene mutation (Val279Phe) between the patient and control groups (P>0.05). CONCLUSION: Neither the mutation of Ile451Met in gene encoding for Desmin exon 8 nor the mutation frequency of PAF-AH gene (G994-->T) has correlation with the DCM.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗

PubMed2006

[HPLC determination and diversity analysis of thiopurine methyltransferase activity in human and pig].

OBJECTIVE: To develop an HPLC method for the determination of 6-methylmercaptopurine concentration and then numerate the thiopurine methyltransferase (TPMT) activity in erythrocyte via formula and analysis of the TPMT activity difference between human and pig. METHODS: The chromatographic apparatus SHIMADZU GC-2010C was used. The stationary phase was a Symmetry C18 reverse-phase column (150 mm x 3.9 mm, 5 microm). The mobile phase was 0.1% acetic acid-methanol and the flow rate 1.0 mL/min. The samples were extracted by ethyl acetate and injected automatically. They were measured at UV 280 nm. 2-amino-6-methyl-mercaptopurine was used as the internal standard. RESULTS: The retention times for 6-MP, AMMP and 6-MMP were 4.4 min, 7.7 min and 9.3 min respectively. The calibration curves were linear over the range of 6.25-100 nmol/mL. the methodology recovery was 98.08%-100.05%. The extraction recovery of 6-MMP was 88.1%-92.4%. The within-group RSD 1.0%-1.5% and inter-group RSD 1.0%-4.4%. The levels of TPMT activity of human, pig and Banna Minipig Inbred Line (BMI) were (17.45 +/- 3.62) U, (7.65 +/- 1.35) U and (8.73 +/- 1.55) U respectively. CONCLUSION: The method is suitable for determination of TPMT activity in erythrocyte of different patients and species in that of clinical medicine and scientific research. TPMT activity of pig and BMI is obviously lower than human's.

Animals↗

PubMed2006

[Detecting the DNA polymorphism of human complement component C8A by PCR-SSCP analysis].

OBJECTIVE: The aim of this study is to establish a new method for detecting the DNA polymorphism of human complement component C8A. METHODS: Based on the point mutation (C-->A) of C8A gene in exon3,The genotypes of 98 unrelated individuals from Han population in Chengdu were studied by polymerase chain reaction-single strand conformation polymorphism(PCR-SSCP)analysis followed by DNA sequencing. RESULTS: The genotypes of C8A * AA, C8A * BB and C8A * AB were observed and the distribution of the genotypes frequencies of C8A in Chengdu Han population was in accordance with Hardy-Weinberg equilibrium. CONCLUSION: The method of PCR-SSCP is reliable, rapid, simple and cost-effective in detecting the DNA polymorphism of C8A, and it is valuable for further application in population genetic study and forensic science practice.

Adult↗

PubMed2006

[Preparation and identification of monoclonal antibody against human GST-Rta150 fusion protein from Epstein-Barr virus].

OBJECTIVE: To prepare a monoclonal antibody (mAb) against GST-Rta150 fusion protein from EB virus and identify its characteristics. METHODS: BALB/c mouse was rendered immune by GST-Rta150 fusion protein; after that, the spleen cells of immunized mouse were taken to fuse with SP2/0 myeloma cells by a routine method. Then screening for positive hybridoma cells and subclone. Following that, the hybridoma cells were injected into the peritoneal cavity of BALB/c mouse. The ascites was collected and purified. The prepared mAb was identified by double immunodiffusion method for its subclass; in addition, its titer and specificity were identified by ELISA and Western-blot, respectively. RESULTS: One hybridoma cell line 1A9 which stably secreted mAb against GST-Rta150 fusion protein was obtained. Its Ig subclass belonged to IgG1, the titer degree of the purified mAb being 10(-6). Western-blot analysis showed the mAb could combine with GST-Rta150 fusion protein specially. The titer degree of this hybridoma cell line remained unchanged after frozen in liquid nitrogen (LN) for three months. CONCLUSION: The mAb obtained by this method has powerful specificity and high stability. This work could serve as a foundation on which to study the Rta protein from EB virus and the diagnosis and treatment of EB virus correlated diseases.

Animals↗