Biomedical subjects

Lin Lin

Publications and source records attributed to Lin Lin.

86 records · Page 5Linked to original sources

PubMed2003

[Using chemical methods to crosslink xenogeneic heart valves: the progress of bioprosthetic heart valves].

Glutaraldehyde clinically is the most commonly accepted crosslinking reagent for bioprosthetic valves preparation. Glutaraldehyde-treated tissue is stable against chemical and enzymatic degradation; however, its calcification and cytotoxicity are severe. Dye-mediated photooxidation is an alternative tissue preservation method that oxidizes the protein with visible light in the presence of a suitable photosensitizer. This article reviews chemical mechanism, research progress, clinical applications future development of these two methods.

Animals↗

PubMed2003

[Construction of mutants of MHC class II molecule transactivator gene capable of suppressing HLA-DR/DQ expression and exploration on their mechanism].

AIM: To construct MHC class II transactivator (CIITA) gene mutants which could suppress the expression of MHC class II molecule and explore its mechanism. METHODS: Restrictive enzymes digestion, PCR and synthesized oligonucleotide strands were used to construct three mutants including pcDNA3mCIITA2, pcDNA3mCIITA3 and pcDNA3mCIITA4. These mutants and pcDNA3 vector were transfected into Hela and Raji cell lines by lipofectamine. RT-PCR and flow cytometry were used to determine the changes of the inducible/constitutive expression of MHC class II-molecule. The mCIITA4 mutant was transferred to the tetracycline dose-dependent plasmid pUHD10-3. By adjusting the concentration of Dox in cultural circumstances, and regulating expressed level of external mutant C II TA, the relationship between the expression level of mC II TA4 mutant and that of MHC class II molecule was observed. RESULTS: pcDNA3mCIITA3 and pcDNA3mCIITA4 could significantly suppress the expression of HLA-DR/DQ gene in Hela and Raji cells, while pcDNA3 empty vector and pcDNA3mCIITA2 had no effect on the MHC class II expression. The inhibition rate of MHC class II molecule expression was directly proportional to the quantity of transfected CII TA mutant. CONCLUSION: The mutants pcDNA3 mCII TA3 and pcDNA3mCIITA4 can suppress the expression of MHC class II gene. Above date confirmed primarily that mutant C II TA suppressed the expression of MHC class II molecule by competitive binding with transactivator for the normal endogenous wild type C II TA molecule.

Gene Expression Regulation↗

PubMed2003

[Overexpression of Penicillium expansum lipase gene in Pichia pastoris].

The alkaline lipase gene of Penicillium expansum (PEL) was coloned into the yeast integrative plasmid pPIC3.5K, which was then transformed into His4 mutant yeast GS115. Recombinant Pichia strains were obtained by minimal olive oil-methanol plates screening and confirmed by PCR. The expression producus of PEL gene was analysis by SDS-PAGE and olive oil plate, the result indicated that PEL gene was functionally overexpressed in Pichia pastoris and up to 95% of the secreted protein. Recombinant lipase had a molecular mass of 28kD, showing a range similar to that of PEL, could hydrolyze olive oil and formed clear halos in the olive oil plates. Four different strategies (different media, pH, glycerol and methanol concentration) were applied to optimize the cultivation conditions, the activity of lipase was up to 260 u/mL under the optimal cultivation conditions. It is pointed out that the absence of the expensive biotin and yeast nitrogen base in the medium increased the lipase production. The possible reason of this result is absence of yeast nitrogen base increased the medium pH during cultivation, and PEL shows a higher stability at this condition. The lipase activity of the supernatant from the culture grown at pH 7 was higher than the one from the culture in the same medium at pH 6.0 is due to the pH stability of PEL too. The results also showed that the methanol and glycerol concentration had a marked effect on the production of lipase.

Enzyme Stability↗

PubMed2002

The hepatocyte nuclear factor 3 alpha gene, HNF3alpha (FOXA1), on chromosome band 14q13 is amplified and overexpressed in esophageal and lung adenocarcinomas.

Genomic amplification is observed in many, if not all, types of human malignancy and is one of the mechanisms for the activation of dominant-acting oncogenes in tumorigenesis. In the present study, three amplified restriction fragments were identified in an esophageal adenocarcinoma (P16) using the restriction landmark genome scanning two-dimensional gel technique. These fragments were cloned, sequenced, and mapped to chromosome band 14q13. Using the sequence tagged site-amplification mapping approach, we defined the core-amplified domain by screening 75 normal-tumor paired esophageal samples. The frequency of 14q13 amplification is 6.7% in esophageal tumors, and the amplicon spans >6 Mb in 1 tumor but is contained in a region <0.3 Mb in all of the remaining amplified tumors. Quantitative reverse transcription-PCR (RT-PCR) of 8 genes and expressed sequence tags located within the core-amplified domain revealed that the HNF3alpha (FOXA1)(4) gene, a forkhead gene family member, was overexpressed in all of the amplified esophageal tumors. HNF3alpha amplification was confirmed by Southern blot and interphase fluorescence in situ hybridization analyses, and the results of real-time RT-PCR were consistent with that of the regular quantitative RT-PCR. Increased immunohistochemical nuclear staining of the HNF3alpha protein was detected in all of the tumors containing 14q13 amplification. Affymetrix oligonucleotide microarrays of 86 lung adenocarcinomas demonstrated that expression of the HNF3alpha mRNA was elevated (> or =2.5-fold of mean expression in normal lung) in 37% (32 of 86) of the tumors analyzed. Gene amplification of HNF3alpha was detected in 2 of the 5 overexpressed lung tumors examined. This is the first report of HNF3alpha amplification, and overexpression in esophageal and lung adenocarcinomas. Amplification of HNF3alpha in esophageal and lung tumors may suggest a potential oncogenic role for this gene in tumorigenesis.

Adenocarcinoma↗

PubMed2002

Functional analysis of calcium-binding EF-hand motifs of visinin-like protein-1.

Visinin-like protein-1 (VILIP-1), a myristoylated calcium sensor protein with three EF-hand motifs, modulates adenylyl cyclase activity. It translocates to membranes when a postulated "calcium-myristoyl switch" is triggered by calcium-binding to expose its sequestered myristoyl moiety. We investigated the contributions of the EF-hand motifs to the translocation of VILIP-1 to membranes and to the modulation of adenylyl cyclase activity. Mutation of residues crucial for binding calcium within each one of the EF-hand motifs indicated that they all contributed to binding calcium. Simultaneous mutations of all of the three EF-hand motifs completely abolished VILIP-1's ability to bind calcium, attenuated but did not eliminate its modulation of adenylyl cyclase activity, and abolished its calcium-dependence for association with cellular membranes. These results show that the calcium-binding EF-hand motifs of VILIP-1 do not have an essential role in modulating adenylyl cyclase activity but instead have a structural role in activating the "calcium-myristoyl switch" of VILIP-1.

Adenylyl Cyclases↗

PubMed2002

The calcium sensor protein visinin-like protein-1 modulates the surface expression and agonist sensitivity of the alpha 4beta 2 nicotinic acetylcholine receptor.

The calcium sensor protein visinin-like protein-1 (VILIP-1) was isolated from a brain cDNA yeast two-hybrid library using the large cytoplasmic domain of the alpha4 subunit as a bait. VILIP-1 is a myristoylated calcium sensor protein that contains three functional calcium binding EF-hand motifs. The alpha4 subunit residues 302-339 were found to be essential for the interaction with VILIP-1. VILIP-1 coimmunopurified with detergent-solubilized recombinant alpha4beta2 acetylcholine receptors (AChRs) expressed in tsA201 cells and with native alpha4 AChRs isolated from brain. Coexpression of VILIP-1 with recombinant alpha4beta2 AChRs up-regulated their surface expression levels approximately 2-fold and increased their agonist sensitivity to acetylcholine approximately 3-fold. The modulation of the recombinant alpha4beta2 AChRs by VILIP-1 was attenuated in VILIP-1 mutants that lacked the ability to be myristoylated or to bind calcium. Collectively, these results suggest that VILIP-1 represents a novel modulator of alpha4beta2 AChRs that increases their surface expression levels and agonist sensitivity in response to changes in the intracellular levels of calcium.

Animals↗

PubMed2002

Gene-expression profiles predict survival of patients with lung adenocarcinoma.

Histopathology is insufficient to predict disease progression and clinical outcome in lung adenocarcinoma. Here we show that gene-expression profiles based on microarray analysis can be used to predict patient survival in early-stage lung adenocarcinomas. Genes most related to survival were identified with univariate Cox analysis. Using either two equivalent but independent training and testing sets, or 'leave-one-out' cross-validation analysis with all tumors, a risk index based on the top 50 genes identified low-risk and high-risk stage I lung adenocarcinomas, which differed significantly with respect to survival. This risk index was then validated using an independent sample of lung adenocarcinomas that predicted high- and low-risk groups. This index included genes not previously associated with survival. The identification of a set of genes that predict survival in early-stage lung adenocarcinoma allows delineation of a high-risk group that may benefit from adjuvant therapy.

Adenocarcinoma↗

PubMed2002

Distinct patterns of apoptosis in the lung during liquid ventilation compared with gas ventilation.

To determine whether liquid ventilation (LV) causes less cell injury and improves lung function compared with conventional gas ventilation (GV), we analyzed pulmonary physiological profiles, lung histology, and cell death in 110- and 120-day preterm lambs, which were randomized to receive either ventilation modality on FI(O(2)) = 1. LV lungs were well expanded with adequate pulmonary function, whereas GV animals exhibited marked atelectasis, poor pulmonary function, and increased mortality. Both ventilatory strategies induced marked lung cell apoptosis, but with distinct patterns of distribution. Although GV induced apoptosis of epithelium primarily in the lining and within the lumina of bronchioles, LV induced significant apoptosis much more homogeneously throughout lung parenchyma including alveoli and interstitial spaces. These studies suggest that although both forms of ventilation cause regional apoptosis, LV more effectively delivers oxygen and recruits the lung more homogeneously than GV.

Animals↗

PubMed2002

Laminin alpha5 chain adhesion and signaling in conjunctival epithelial cells.

PURPOSE: To identify peptides of the LG4 module of the laminin alpha5 chain that mediate human conjunctival epithelial cell adhesion to the laminin-10 isoform. METHODS: A peptide corresponding to a major heparin- and cell-binding domain of the LG4 module of the laminin alpha5 chain was analyzed. The attachment of conjunctival epithelial cells to the peptide compared with laminin-10 was determined by colorimetric adhesion assay. The role of glycosaminoglycans in mediating adhesion to the peptide was determined by altering their function at the cell surface and by blocking adhesion with exogenous glycosaminoglycans. The role of syndecan-4 in cell adhesion to the peptide was examined by adhesion assay. The role of the peptide in cell signaling was examined by phosphotyrosine Western blot analysis. RESULTS: The peptide facilitated the adhesion of conjunctival epithelium, although not as efficiently as laminin-10. Heparinase had no effect on adhesion to the peptide. In contrast, adhesion to the peptide decreased in glycosaminoglycan-deficient cells, heparatinase-treated cells, cells blocked with exogenous heparan sulfate proteoglycan, and cells treated with antibodies to the ectodomain of syndecan-4. Cell adhesion to the peptide for 90 or 120 minutes resulted in a significant increase in focal adhesion kinase (FAK) tyrosine phosphorylation, compared with the nonadherent control. CONCLUSIONS: Human conjunctival epithelial cells use a heparin- and cell-binding peptide of the LG4 module of laminin alpha5 chain in adhesion to laminin-10. Syndecan-4 is one mechanism by which the peptide facilitates adhesion. In addition to adhesion, the peptide may function in cell-signaling events.

Blotting, Western↗

PubMed2002

[Cloning and prokaryotic expression of viral binding protein(VBP) gene from endosybiotic bacterium of Rhopalosiphum padi].

Viral binding protein gene from Rhopalosiphum padi Yangling biotype was amplified by PCR method and then cloned. The complete nucleotide sequence of the gene was determined, It has 1647 nucleotides encoding 548 amino acids. Comparison showed this gene has 97% identity on nucleotide level with Buchnera groEL-AM gene of Rhopalosiphum padi American biotype, while has 97.4% identity on amino acid level was found between this two genes. The VBP gene was ligated into pBV221 and pET30a expression vector and expressed the aim protein 63 kD and 69 kD.

Amino Acid Sequence↗

PubMed2002

[Determination of trace palladium in medicament by electric-heated AAS with molybdenum-coated graphite tube].

This paper reports a new method for the determination of palladium in exported medicament doxycycline hydrochloride by graphite furnace atomic absorption spectrometry. The optimum conditions for the determination of trace Pd were investigated in details. When the graphite tube was coated with molybdenum, the sensitivity was enhanced and when EDTA was used as the matrix modifier the matrix interference was eliminated efficiently. The result indicates that the detection limit for Pd is 4.6 x 10(-10) g and the relative standard deviation is 4.3%. The method is accurate and rapid and can be used successfully to determine actual samples. The recovery rate of palladium is in the range of 97.1% to 103.3%.

Doxycycline↗

PubMed2002

[Determination of trace barium in environmental samples by electric-heated AAS with lanthanum-coated graphite tube].

In this paper a new method was established for determination of trace barium in environmental samples by graphite furnace atomic absorption spectrometry. In the presence of matrix modifier magnesium nitrate, the matrix inference was eliminated efficiently. To avoid producing barium carbide, the graphite tubes were coated differently with lanthanum, zirconium, tungsten, molybdenum, and tantalum. Results showed that the tube with lanthanum was the best. The atomization temperature was diminished. The sensitivity was improved, and the tube with lanthanum gave the longest service life. So we used the tube to determine trace barium. The trace barium in Geodchemical Standard Reference Sample Soil-1 (GSS-1) was determined by the new method, the test results showed that the method was reliability and accurate. The method has been used for the determination of trace barium in environmental samples and in water of Yellow River. The detection limit for Ba was 2.1 x 10(-12) g and the relative standard deviation(RSD) was 5.4% for 15 ng.mL-1 Ba.

Barium↗

PubMedDate not supplied

Mutations in the p53 tumor suppressor gene and early onset breast cancer.

Among breast cancer patients p53 gene mutation is associated with a poor prognosis. Young women with breast cancer are more likely than older women to have a poor prognosis, but whether p53 gene mutation plays a role in breast cancer in young women is not clear. This study identified 199 breast cancer patients and tested the hypothesis that p53 gene mutation was associated with early onset breast cancer. Patients with p53 gene mutations were 3-times more likely to have an early onset breast cancer (age < or = 40 years at diagnosis) than those without p53 mutations (OR = 3.05, 95% CI = 1.10-8.45). Patients with both missense and silent mutations were 7-times more likely to have a diagnosis of early onset breast cancer (OR = 7.56, 95% CI = 2.22-25.8). Patients with mutations in exon 8 of the p53 gene were 6-times more likely to be diagnosed with early onset breast cancer (OR = 6.48, 95% CI = 1.37-30.6). These findings suggest that p53 gene mutation may hasten the onset of female breast cancer.

Adult↗

PubMedDate not supplied

Study on the expression of RXRalpha in patients with psoriasis vulgaris.

Retinoic acid regulates keratinocyte proliferation and differentiation--processes that are disturbed in psoriatic skin--via binding to nuclear receptors, including retinoic acid receptor (RAR-alpha,beta,gamma) and the common heterodimer partners (RXR-alpha,beta,gamma). By RT-PCR and immunohistochemistry methods, the expression of RXRalpha was studied in psoriatic skin and controls. The expression of RXRalpha was down-regulated in patients with psoriasis; moreover, its level was related to the stage of the disease; in the progressive stage of the disease, the level of the RXRalpha was lower than in the stable stage. The results suggest that retinoid signaling is abnormal in lesional psoriatic skin, RXRalpha expression is mainly confined to differentiated keratinocytes.

Adolescent↗