Biomedical subjects

Yong You

Publications and source records attributed to Yong You.

33 records · Page 2Linked to original sources

PubMed2004

Upregulation of surfactant synthesis triggers ABCA1-mediated basolateral phospholipid efflux.

Alveolar type II lung epithelia produce surfactant, an essential surface-active material highly enriched with disaturated phosphatidylcholine (DSPC), which requires a key regulatory enzyme, CTP:phosphocholine cytidylyltransferase alpha (CCTalpha), for its synthesis before its export apically into the alveolus. In this study, we examined whether surfactant phosphatidylcholine (PC) synthesis and export are physiologically linked. Stable overexpression of CCTalpha in lung epithelial cell lines increased rates of PC synthesis and cellular DSPC mass without altering total cellular PC content. Overexpression of CCTalpha was associated with i) increased basolateral, rather than apical, PC export catalyzed by ABCA1; ii) basolateral export of significant levels of unsaturated (nonsurfactant) PC; and iii) transcriptional activation of the ABCA1 gene via a liver X receptor/retinoic acid receptor-independent pathway. Cells exposed to PC vesicles exhibited a dose-dependent increase in ABCA1 transcriptional activity. These data provide the first evidence that surfactant PC synthesis is linked to its export via a basolateral lipid efflux pathway. This pathway is mediated, in part, by a phospholipid sensor, ABCA1, that appears to partake in the autoregulation of both cellular content and composition of PC, thereby providing a potentially novel exit route for a newly synthesized pool of PC distinct from surfactant.

ATP Binding Cassette Transporter 1↗

PubMed2004

Effects of sodium ions on DNA duplex oligomers: improved predictions of melting temperatures.

Melting temperatures, T(m), were systematically studied for a set of 92 DNA duplex oligomers in a variety of sodium ion concentrations ranging from 69 mM to 1.02 M. The relationship between T(m) and ln [Na(+)] was nonlinear over this range of sodium ion concentrations, and the observed melting temperatures were poorly predicted by existing algorithms. A new empirical relationship was derived from UV melting data that employs a quadratic function, which better models the melting temperatures of DNA duplex oligomers as sodium ion concentration is varied. Statistical analysis shows that this improved salt correction is significantly more accurate than previously suggested algorithms and predicts salt-corrected melting temperatures with an average error of only 1.6 degrees C when tested against an independent validation set of T(m) measurements obtained from the literature. Differential scanning calorimetry studies demonstrate that this T(m) salt correction is insensitive to DNA concentration. The T(m) salt correction function was found to be sequence-dependent and varied with the fraction of G.C base pairs, in agreement with previous studies of genomic and polymeric DNAs. The salt correction function is independent of oligomer length, suggesting that end-fraying and other end effects have little influence on the amount of sodium counterions released during duplex melting. The results are discussed in the context of counterion condensation theory.

Base Pairing↗

PubMed2004

Expression of CII TA gene in five human malignant hematological cell lines and its significance.

The role of MHC class II transactivator (C II TA) in constitutive or IFN-gamma inducible expression of HLA molecules in human malignant hematological cell lines was investigated. The expression of HLA molecules and C II TA protein was detected by Western blot, immunohistochemistry and flow cytometry. The expression of C II TA gene was determined by RT-PCR. The capability of peripheral blood T cell reaction stimulated by tumor cells was monitored by mixed lymphocyte reaction. It was found that the HLAII-positive tumor cells expressed the C II TA quite well, and the expression of HLA I + II was increased in the tumor cells with constitutive or inducible expression of C II TA after induced by IFN-gamma. The tumor cells which did not express C II TA after induced by IFN-gamma were not response to the expression of HLA II promoted by IFN-gamma. It suggests a correlation between the inability of some malignant hematological cell lines in response to IFN-gamma for HLA expression and the deficiency in the inducible expression of C II TA, indicating C II TA might take part in the regulation of HLA I + II expression in the tumor cells, which might play an important role in tumor immunologic escape.

Animals↗

PubMed2004

Arsenic trioxide inhibits proliferation in K562 cells by changing cell cycle and survivin expression.

To study the mechanisms involved in the inhibition of chronic myeloid leukemic cells (K562) proliferation induced by arsenic trioxide (As2O3) and to explore the potential role of Survivin, an inhibitor of apoptosis protein, in the regulation of As2O3 induced cell apoptosis, K562 cells were cultured with As2O3 of different concentrations. Cells were collected for proliferation analysis by MTT assay. Cell cycle distribution and cell apoptosis were analyzed by flow cytometry. Expression of Survivin protein and mRNA were detected by flow cytometry and RT-PCR, respectively. Our results showed that As2O3(2-10 micromol/L) inhibited K562 cells growth effectively, but it did not induce cells apoptosis significantly. The percentage of K562 cells at G2/M phase increased in proportion to As2O3 concentrations, and the expression of Survivin mRNA and content of Survivin protein was up-regulated accordingly. It is concluded that As2O3 inhibited K562 cells growth by inducing cell cycle arrest mainly at G2/M phase. Over-expression of Survivin gene and protein might be one of the possible mechanisms contributing to K562 cells' resistance to As2O3-induced apoptosis.

Antigens, Neoplasm↗

PubMed2004

Inhibition of Fas-mediated apoptosis in Yac-1 cell via Anti-Fas ribozyme.

To detect a new and more effective way against apoptosis mouse lymphomatic cell line Yac-1 in which fas gene was expressed highly was used as a model for studying the effects of anti-Fas ribozyme on Fas-mediated apoptosis. A hammerhead ribozyme gene targeting the fas mRNA was synthesized and its in vitro transcription vector was constructed, which was transfected into Yac-1 cells using electroporation. Rz596 expression was detected using RT-PCR, and Fas expression in Yac-1 cells was detected using RT-PCR, Western blot and flow cytometry. After treated with anti-Fas antibody (JO2), Yac-1 cell viability was measured with MTT assay, caspase-3 proteolytic activity was detected, and cell apoptosis was measured according to annexin V apoptosis detecting kit. Anti-Fas ribozyme could cleave fas mRNA efficiently in vivo and in vitro. Fas expression in Yac-1 cells transfected with anti-Fas ribozyme was decreased remarkably and correlated with resistance to Fas-mediated apoptosis as determined by flow cytometry and caspase-3 proteolytic activity. Anti-Fas ribozyme was detected in cells transfected with pU6-RZ596 and pU6-dRZ596 and could remarkably decrease the Fas expression in Yac-1 cells, which made Yac-1 cells get rid of Fas-mediated apoptosis. Because of wide expression of fas in organs and tissues, our research was very useful for studying the inhibition of apoptosis of many organs and tissues in the future.

Animals↗

PubMed2004

Inhibiting apoptosis of CTLL-2 cells to enhance their GVL effects via anti-Fas ribozyme.

To investigate the inhibition role of anti-Fas hammerhead ribozyme on fas expression and Fas-mediated apoptosis of CTL cell line CTLL-2 cells, the cDNA of an anti-Fas hammerhead ribozyme was synthesized, its expression plasmid was constructed and transfected into CTLL-2 cells by electroporation. fas expression of CTLL-2 cells was detected by RT-PCR and Western blot. CTLL-2 cell viability was measured using MTT assay when co-cultured with mouse T cell leukemia cell line EL4 cells that highly expressed Fas ligand (FasL). Meanwhile, caspase-3 proteolytic activity was detected, and cell apoptosis was measured by flow cytometry and Hochest-PI double staining. Killing activity of CTLL-2 cells was detected by lactate dehydrogenase (LDH) releasing assay in vitro. Results showed that the expression of both Fas mRNA and protein in CTLL-2 cells were decreased after transfection of anti-Fas ribozyme. Compared with mock-transfected group and mutant ribozyme-transfected group, viability of CTLL-2 cells co-cultured with EL4 cells was increased significantly and cells killing activity was enhanced after transfected with anti-Fas ribozyme, while the caspase-3 activity and apoptosis rate was significantly decreased. The results demonstrated anti-Fas ribozyme could efficiently cleave Fas and inhibit Fas-mediated apoptosis of CTLL-2 cells to improve their viability. Our study made a basis for enhancing CTLL-2 cells anti-leukemia effect in DLI.

Animals↗

PubMed2004

[Role of apoptosis in cryoinjury of cord blood hematopoietic stem/progenitor cells and its mechanism].

To investigate the role and mechanism of apoptosis in cryoinjury of cord blood hematopoietic stem/progenitor cells, apoptosis of CD34(+) cells, mitochondrial membrane potential (MMP) and Fas antigen expression were detected by flow cytometry (FCM), the Bcl-2 protein expression was detected by immunohistochemistry, caspase-3 expression was determined by Western blot and caspase-3 activity analysis, colony-forming units (CFU) was performed by semi-solid methylcellulose culture. The results showed that when cells were store at -196 degrees C for 2 weeks or 4 weeks, apoptotic cells increased, gel electrophoresis displayed typical DNA ladder, and CFU decreased by 25.2% and 30.1%. The value of MMP reduced and expression of Bcl-2 protein was down-regulated during the freeze-thaw process, but the Fas antigen expression was not effected. However, only the 32 kD inactive caspase-3 proenzyme was detected in freshly isolated CD34(+) cells. After freeze-thaw, caspase-3 was activated and a cleavage of 20 kD protein was detected. Cryopreserved cells showed a 1.2-fold and 1.5-fold increase in caspase-3 activity, respectively. It is concluded that apoptosis plays an important role in cryoinjury of cord blood hematopoietic stem/progenitor cells, which triggers a mitochondrial apoptotic pathway that is caspase-dependent but does not require death receptors, where caspase-3 is the key effector.

Antigens, CD34↗

PubMed2004

[The expression and significance of major histocompatibility complex II transactivator gene in five human malignant hematological cell lines].

OBJECTIVE: To investigate the role of major histocompatibility complex (MHC) II transactivator in constitutive or interferon (IFN)-gamma inducible expression of MHC molecules in human malignant hematological cell lines. METHODS: The expression of MHC molecules and MHC class II transactivator (CIITA) protein were detected with Western blot, immunohistochemistry and flow cytometry. The expression of CIITA gene was determined with RT-PCR. T cell expressing interleukin (IL)-2 mRNA was induced by Jurkat with mixed lymphocyte reaction. RESULTS: It was found that the MHCII-positive tumor cells expressed the CIITA quite well, and IFN-gamma could induce the expression of MHCI + II only if the tumor cells were able to express CIITA in an IFN-gamma induced manner (20%, 42% for Jurkat cells respectively), while T cell expressed more IL-2 mRNA (51 times) in the case of Jurkat after induction with IFN-gamma. CONCLUSIONS: It is suggested that there is a correlation between the inability of the tumor cells in response to IFN-gamma for MHC expression and the deficiency in the inducible expression of CIITA. This might be due to immune sneaking through the tumor cells to some extent.

Blotting, Western↗

PubMed2004

[Distribution and efficiency of recombinant adenovirus mediated hVEGF165 gene transfer in bone marrow transplanted mice].

OBJECTIVE: To investigate the rapid construction of enhanced green fluorescent protein (EGFP) labeled recombinant adenovirus containing hVEGF165 and its distribution and efficiency in bone marrow transplanted mice. METHODS: The recombinant adenovirus Ad-EGFP/hVEGF165 was rapidly constructed by using AdEasy system based on the homologous recombination in bacteria, and its property was studied in vitro. Then 3x10(8) PFU adenovirus was injected into BALB/c mice via the tail vein accepted syngeneic bone marrow transplantation. The in vivo distribution of adenovirus and plasma levels of VEGF were measured at different phases. RESULTS: The adenovirus Ad-EGFP/hVEGF165 was quickly constructed by homologous recombination in bacteria using AdEasy system. The purified particles were homogenous hexagon with titers between 10(10) PFU/ml and 10(11) PFU/ml. The Hela cells infected with Ad-EGFP/hVEGF165 did not show cytopathic effects after several times passages. Under the fluorescent microscope, EGFP was revealed in the heart, lung, liver, spleen, kidney and intestine of mice at different phases. RT-PCR and immunohistochemistry showed hVEGF165 expressed significantly. No obvious damages were observed in different organs by HE staining. The plasma level of hVEGF165 was up to 866.67+/-97.13 pg/ml. CONCLUSION: These results suggested that the construction of adenovirus vector by homologous recombination in bacteria was an efficient and time-saving method, and high titer adenovirus could successfully mediate the safe and stable expression of hVEGF165 in post bone marrow transplanted mice. All these would make further gene therapy in bone marrow transplantation possible.

Adenoviridae↗

PubMed2004

[Study on the expression of hematopoietic growth factor gene in human umbilical vein endothelial cells using gene chip].

In order to detect the hematopoietic growth factor gene expressed in human umbilical vein endothelial cells using gene chip, human umbilical vein endothelial cells (ECV304) were cultured in vitro and divided into VEGF group and control group in same medium. 50 ng/ml hVEGF165 was added in the VEGF group. After culture for 24 hours all cells were collected for total RNA extraction. Then, cDNAs were marked with Cy3 and Cy5 for control group and VEGF group, respectively, and hybridized with gene chip. Hybridization signals were collected and analyzed following scanning by laser co-focal microscopy. The results showed that a large number of hematopoietic growth factor and receptor genes (Epo/R, GM-CSF/R, G-CSF/R, LIF, IL-3, TPO, Flt-3, SCF) were expressed in both groups, while many other growth factors (VEGF, IGF2, PDGFA, PDGFB, TGFbeta1) and receptors (neuropilin-1, neuropilin-2, TGFbeta-R1)were expressed. The differentially expressed genes amounted to 24. It is concluded that many hematopoietic growth factors and receptors expressed by hUVECs could be analyzed in a short period by using gene chip, which provides a powerful method for further studies on characteristics of vascular endothelial cells.

Cells, Cultured↗

PubMed2004

[Alkaloids of the hairy roots of Ipomoea batatas Lam].

AIM: To study the alkaloid constituents of the hairy roots of Ipomoea batatas Lam. METHODS: Chromatographic methods were used for isolation and purification. The structure was elucidated on the basis of spectral data. RESULTS: An alkaloid was isolated from the hairy roots of Ipomoea batatas. CONCLUSION: The compound is a novel indole-type alkaloid, which is named as ipomine A.

Indole Alkaloids↗

PubMed2004

[Experimental study of inhibiting CTLL-2 cell apoptosis and enhancing cytotoxicity to Yac-1 cell by hammerhead ribozyme].

OBJECTIVE: To investigate the inhibition role of anti-Fas hammerhead ribozyme on Fas expression and Fas-mediated apoptosis in mouse cytotoxic T lymphocyte (CTL) cell line--CTLL-2 cells, and explore a novel approach to enhance the ability of T cells against leukemia in donor lymphocytes infusion (DLI). METHODS: A hammerhead ribozyme targeting the Fas mRNA was synthesized and transfected into CTLL-2 cells by electroporation. Fas expression in CTLL-2 cells was detected by using RT-PCR, Western blot and flow cytometry, CTLL-2 cells viability was measured by MTT assay, caspase-3 proteolytic activity by caspase-3 detection kit, and cell apoptosis by flow cytometry. Killing activity of CTLL-2 was detected by LDH releasing assay in vitro. RESULTS: Expression of Fas mRNA and protein in CTLL-2 cells was reduced to 50% after transfection with anti-Fas ribozyme. Being treated with anti-Fas antibody (JO(2)), compared with control and mock-transfected cells, viability of CTLL-2 cells transfected with anti-Fas ribozyme increased by 1-fold, caspase-3 activity and apoptosis rate of ribozyme-transfected cells decreased to 50% and 37%, respectively, and cell killing activity was enhanced by 2-fold. CONCLUSION: Anti-Fas ribozyme can cleave Fas efficiently and inhibit Fas-mediated apoptosis of CTLL-2 cells, resulting in improvement of their viability.

Animals↗

PubMed2003

The CCT promoter directs high-level transgene expression in distal lung epithelial cell lines.

Gene therapy requires the presence of a robust and yet small promoter to drive high-level expression of desired proteins. In comparative analysis, we investigated the promoter strength of the CTP:phosphocholine cytidylyltransferase promoter (CCT alpha) with other commonly used promoters, which were all cloned into a similar background vector (PGL3 basic). Transient promoter-reporter assays in murine lung epithelial (MLE-12) cells revealed that the core CCT alpha promoter (240 bp) was observed to exhibit a 40-fold, 8-fold, and 3-fold higher level of activity compared with the simian virus 40, human cytomegalovirus, and Rous sarcoma virus promoters, respectively. The CCT alpha promoter was significantly more active than the Clara cell 10, thymidine kinase, and phosphoglycerate kinase promoters. This pattern of high-level expression for CCT alpha was detected primarily in cell lines of distal lung epithelial origin (MLE-12, RLE, H441) and was reduced in other cell lines (A549, CHO, HepG 2). CCT alpha promoter-reporter activity, CCT alpha transcript levels, and immunoreactive protein levels increased significantly in the presence of all-trans retinoic acid. The CCT alpha promoter, in a retinoic acid-inducible manner, efficiently directed expression of murine erythropoietin in MLE-12 cells. Collectively, these observations suggest that the CCT alpha construct might be useful to drive high-level, regulatable expression of heterologous proteins in alveolar epithelia.

Animals↗

PubMed2003

[Effects of metoclopramide on intelligence and memory in patients with Tourette syndrome].

OBJECTIVE: To investigate the effects of metoclopramide on the intelligence and memory in patients with Tourette syndrome. METHODS: Before and after the 3 month treatment of metoclopramide, the intelligence of 25 children with Tourette syndrome was evaluated by the Wechsler intelligence scale fo children, and the memory by the Wechsler memory scale for children. RESULTS: The scores of intelligence in children treated by metoclopramide increased from 82.27 +/- 13.20 to 90.53 +/- 15.50, with significant difference (P < 0.05). The scores of performance intelligence quotient increased from 84.13 +/- 10.60 to 92.40 +/- 15.30 (P < 0.01). The scores of arithmetic subtle test for the support memory/attention, the block pattern subtle test for the support perception constitution factor, and the vision recognition subtle test for mean short-term memory increased from 8.20 +/- 2.70 to 10.20 +/- 3.21, 9.13 +/- 2.33 to 10.53 +/- 2.94, and 6.07 +/- 4.56 to 8.40 +/- 3.56, respectively. CONCLUSION: Metoclopramide can improve the intelligence, short-term memory and attention in children with Tourette syndrome.

Adolescent↗

PubMed2003

[The use of serum nitric oxide level and cyclic guanosine monophosphate level as predictors of preterm delivery].

OBJECTIVE: To investigate the possibility of using nitric oxide and cyclic guanosine monophosphate (cGMP) levels as predictors of preterm delivery. METHODS: Two hundred and thirty pregnant women were enrolled in this study; among them were 210 normal pregnant women (from 28 to 36(+6) gestational weeks) and 40 preterm pregnant women (from 36 to 36(+6) gestational weeks). The serum nitric oxide and cGMP levels were examined by oscillopolarography and radioimmunoassay, respectively. RESULTS: In the normal pregnant women (from 28 to 36(+6) gestational weeks) , the serum nitric oxide level gradually increased from 1.9575 +/- 0.3509 to 2.2360 +/- 0.3486 micromol/L, and the serum cGMP level increased from 31.1625 +/- 3.9082 to 42.1850 +/- 11.3816 micromol/L as well. The highest levels of serum nitric oxide and cGMP were found in the 34-34(+6) and 33-33(+6) gestational weeks, respectively. The serum nitric oxide and cGMP levels in the preterm pregnant women were significantly lower as compared with those in the normal pregnant women (P < 0.01, P < 0.05), respectively. CONCLUSION: This study has demonstrated great possibilities in the use of serum nitric oxide and cGMP levels as predictors of preterm delivery. Further investigation needs to be performed.

Adult↗