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Biomedical subjects

Yi Sun

Publications and source records attributed to Yi Sun.

At least 73 records · Page 4Linked to original sources
PubMed2005

[The changes of some vasoactive substances after operation in patients with obstructive sleep apnea-hypopnea syndrome].

OBJECTIVE: To observe the changes of thromboxane B2 (TXB2), rennin, angiotensin II (AT-II), endothelin 1 (ET-1) and anticardiolipin antibody (ACA) in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) before and after the operation. METHOD: Fifty-four cases of OSAHS confirmed by polysomnography (PSG) were selected as the OSAHS group and 20 normal donors without OSAHS were selected as the control group. Plasma levels of TXB2, rennin, AT- II, ET-1 and ACA were detected by enzyme-linked immunosorbent assay (ELISA). RESULT: Plasma levels of TXB2, rennin, AT-II, ET-1 and ACA were higher in patients with OSAHS than those in control group (P < 0.05 or P < 0.01), and the operation therapy decreased them significantly (P < 0.05 or P <0.01). All the plasma parameters were correlated positively with AHI, and negatively with SaO2. CONCLUSION: The results indicate the patients with OSAHS were susceptible to thromboembolism disease. Operation therapy is effective in correcting TXB2, rennin, AT-II, ET-1 and ACA.

Angiotensin II↗
PubMed2005

[Cloning and expression of androgen response elements of prostate specific antigen promoter].

OBJECTIVE: To provide a possible targeted gene therapy scheme for prostate cancer, and explore the expression efficiency and tissue-specific expression of prostate specific antigen (PSA) promoter. METHODS: Three plasmids with egfp, pa-EGFP(including ARI, ARII), pba-EGFP (including ARI, ARII, ARIII) and pdeltaba-EGFP (including ARI, ARII and mutated ARIII) were designed, and the expression status was observed by transfecting into HepG2, SMMC-7721, Hela and PC-3. RESULTS: In prostate cancer cell PC-3, pba-EGFP expressed more GFP than pa-EGFP and pdeltaba-EGFP, which showed that ARIII could notably increase the transcription efficiency of PSA promoter. Further, there was no GFP expression in HepG2, SMMC-7721 and Hela transfected with pa-EGFP, p deltaba-EGFP and pba-EGFP. CONCLUSION: An expression vector based on elements of the PSA gene regulatory sequences has been developed and shown to be tightly regulated in a panel of cells from tissues of various origins. With the tissue-specific functional protein, it should provide a solid platform for clinical studies.

Androgens↗
PubMed2004

An unprecedented intramolecular coupling of o-carboranyl and cyclopentadienyl. Synthesis and structural characterization of a ruthenium complex containing a novel doubly-bridged cyclopentadienyl-carboranyl ligand.

A novel ruthenium-mediated coupling reaction of a carboranyl with a cyclopentadienyl was discovered for the first time, leading to a brand new doubly-bridged cyclopentadienyl-carboranyl ligand bearing two five-membered rings and to a new type of chiral ruthenium complex.

Journal Article↗
PubMed2004

Biophysical characterization of natural and mutant fluorescent proteins cloned from zooxanthellate corals.

Two novel colored fluorescent proteins were cloned and biophysically characterized from zooxanthellate corals (Anthozoa). A cyan fluorescent protein derived from the coral Montastrea cavernosa (mcCFP) is a trimeric complex with strong blue-shifted excitation and emission maxima at 432 and 477 nm, respectively. The native complex has a fluorescence lifetime of 2.66+/-0.01 ns and an inferred absolute quantum yield of 0.385. The spectroscopic properties of a green fluorescent protein cloned from Meandrina meandrites (mmGFP) resemble the commercially available GFP derived originally from the hydrozoan Aequorea victoria (avGFP). mmGFP is a monomeric protein with an excitation maximum at 398 nm and an emission maximum at 505 nm, a fluorescence lifetime of 3.10+/-0.01 ns and an absolute quantum yield of 0.645. Sequence homology with avGFP and the red fluorescent protein (DsRed) indicates that the proteins adopt the classic beta-barrel configuration with 11 beta-strands. The three amino acid residues that comprise the chromophore are QYG for mcCFP and TYG for mmGFP, compared with SYG for avGFP. A single point mutation, Ser-110 to Asn, was introduced into mmGFP by random mutagenesis. Denaturation and refolding experiments showed that the mutant has reduced aggregation, increased solubility and more efficient refolding relative to the wild type. Time-resolved emission lifetimes and anisotropies suggest that the electronic structure of the chromophore is highly dependent on the protonation state of adjoining residues.

Animals↗
PubMed2004

A preliminary study on chitosan and gelatin polyelectrolyte complex cytocompatibility by cell cycle and apoptosis analysis.

In this study, L929 cell adhesion, proliferation and apoptosis were investigated on chitosan (CS) and chitosan-gelatin (CS-Gel) membranes having different degrees of deacetylation (DD). The mitochondrial activity [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay results demonstrated that the DD played a key role in the L929 cell adhesion. Indeed, the higher the DD of a CS membrane, the stronger the cell adhesion. The cell cycle analysis showed that the CS surface inhibits most of the cells entering the cell cycle and the DD of CS had little effect on the cell cycle progression. On the other hand, this study also confirmed that CS, blended with Gel, induced L929 cells to enter the cell cycle, encouraged proliferation, decreased the degree of apoptosis on the CS membranes, and are comparable to the results from L929 cells on tissue culture plates. In brief, CS modified with Gel improves cytocompatibility by shielding the positively charged CS with a high charge density.

Animals↗
PubMed2004

Increase of circulating CD4+CD25+ T cells in myasthenia gravis patients with stability and thymectomy.

BACKGROUND: CD4(+)CD25(+) regulatory T cells are key controllers of peripheral immunological self-tolerance and suppress various autoimmune diseases in animal models, but few studies have been done to define their roles in myasthenia gravis (MG) so far. OBJECTIVE: To investigate frequencies and dynamic changes of blood CD4(+)CD25(+) T cells from MG patients. METHODS: The peripheral blood CD4(+)CD25(+) T cells of 29 MG patients and 23 healthy controls were detected by three-color flow cytometry. RESULTS: Myasthenic patients with symptomatically uncontrollable disease showed slightly lower percentages of CD4(+)CD25(+) T cells (mean = 3.79 +/- 1.40%; P = 0.12), whereas MG patients with clinically stable disease had significantly increased CD4(+)CD25(+) T cells (mean = 8.45 +/- 1.96%, P = 0.0001), as compared with healthy controls (mean = 4.53 +/- 0.96%). In addition, thymectomized MG patients had significantly higher percentages of CD4(+)CD25(+) T cells (mean = 8.44 +/- 2.39%), as compared with both non-thymectomized MG patients (mean = 5.88 +/- 2.89%, P = 0.038) and healthy controls (P = 0.003). CONCLUSIONS: Our observations indicate that increased percentages of CD4(+)CD25(+) T cells in MG patients may be related to disease stability and that thymectomy in patients with MG resulted in augmented CD4(+)CD25(+) T cells.

Adolescent↗
PubMed2004

The complete mitochondrial genomes sequences of Asio flammeus and Asio otus and comparative analysis.

The complete mitochondrial genomes of Asio flammeus and Asio otus were sequenced and found to span 18858 bp and 18493 bp, respectively. It is surprising to find the former to be the largest among all avian mitochondrial genomes sequenced so far. The two genomes have very similar gene order with that of Gallus gallus, neither contains the pseudo control region, but both have a single extra base, namely Cytidine, at position 174 in ND3 gene. The control regions of Asio flammeus and Asio otus' mitochondrial genomes span 3288 bp and 2926 bp respectively, which are the longest among vertebrates except for Myxine glutinosa and contribute to the large size of two genomes. The 3' end of the control region of Asio flammeus and Asio otus contains many tandemly repeated sequences, which are highly similar to a putative control element, i.e. Mt5, and may form stable stem-loop secondary structures. Such repeated sequences probably play an important role in regulating transcription and replication of mitochondrial genome. Our results may provide important clues for uncovering the origin and evolution mechanisms of mitochondrion genome.

Animals↗
PubMed2004

[Identification of acute leukemia-specific genes from leukemia recipient/sibling donor pairs by distinguishing study with oligonucleotide microarrays].

To explore differentially expressed genes in leukemia gene expression profile and identify main related genes in acute leukemia, gene expression profiles were analyzed in bone marrow/leucopheresis peripheral blood stem cells samples from 9 acute leukemia patients and their sibling donors with the use of oligonucleotide microarrays. 163 reported leukemia-related genes were involved in the study. The oligonucleotide primers were designed, synthesized and spotted on the chemical-material-coated-glass plates in array. The total RNAs were isolated from nine patients' bone marrow or leucopheresis peripheral blood cells and from nine their sibling donors peripheral blood stem cells treated by G-CSF, then collected by CS-3000 cell selection machine, and were reversely transcribed to cDNAs with the incorporations of fluorescent dUTP. The mixed probes were then hybridized to the oligonucleotide microarray. The results showed that in four patient/donor pairs with B-ALL, 5 up-regulated (RIZ, STK-1, T-cell leukemia/lymphoma 1A, Cbp/p300, Op18) and 1 down-regulated genes (hematopoietic proteoglycan core protein) were identified; In five patient/donor pairs with AML-M(4) and AML-M(5), 6 up-regulated (STAT5B, ligand p62 for the Lck SH2, CST3, LTC4S, myeloid leukemia factor 2 and epb72) and 1 down-regulated genes (CCR5) were identified. In conclusion, on the basis of distinguishing study of specific genetic related recipient/sibling donor pairs, screening leukemia-related genes with oligonucleotide microarrays, a set of 13 up-regulated or down-regulated genes among 163 leukemia-related genes has been identified. The result has further confirmed that above genes play critical role in the molecular mechanism of acute leukemia.

Blood Donors↗
PubMed2004

Gene expression changes induced by green tea polyphenol (-)-epigallocatechin-3-gallate in human bronchial epithelial 21BES cells analyzed by DNA microarray.

Many studies suggest green tea is a cancer chemopreventive agent. This effect has been attributed to its major constituent (-)-epigallocatechin-3-gallate (EGCG). EGCG is also observed to have cytotoxic anticancer effects, especially when used in combination with certain chemotherapeutic agents. The biochemical actions of EGCG in chemoprevention and anticancer effects have been studied; however, the mechanisms of action are not clearly understood. We show here by expression genomics the effects of EGCG (25 micromol/L) in the Ha-ras gene transformed human bronchial epithelial 21BES cells. We found induction of temporal changes in gene expression and the coalescence of specific genetic pathways by EGCG. In this experimental system, hydrogen peroxide (H2O2) was produced. By treating cells with EGCG in the presence or absence of catalase, we further distinguished gene expression changes that are mediated by H2O2 from those that are H2O2 independent. Many genes and cellular pathways, including genes of the transforming growth factor-beta signaling pathway, were H2O2 dependent because the effects were abolished by catalase. Gene expression changes that were not affected by catalase included those of the bone morphogenetic protein signaling pathway, peptidylprolyl isomerase (cyclophilin)-like 2, alkylated DNA repair enzyme alkB, polyhomeotic-like 2, and homeobox D1. We show further that EGCG and H2O2 differentially transactivated the bone morphogenetic protein and the transforming growth factor-beta response element promoter reporters, respectively, thus confirming results from DNA microarray analysis. The elucidation of gene expression changes between H2O2-dependent and H2O2-independent responses helps us better understand the cancer chemopreventive and anticancer actions of EGCG.

AlkB Homolog 1, Histone H2a Dioxygenase↗
PubMed2004

Synergistic effects of androgen and estrogen on the mouse uterus and mammary gland.

Many studies have suggested that elevated estrogens and androgens may be etiologically related to the development of breast cancer, endometrial cancer and uterine leiomyomas. We and other investigators have previously shown that estrogen and androgen are synergistic in the induction of mammary carcinogenesis in the Noble rat. However, the mechanisms behind the synergy is unknown, and it is unclear whether such synergy is unique for the Noble rat and for the mammary gland. In this study we treated female FVB mice with 17beta-estradiol (E2) and 5alpha-dihydrotestosterone-bezonate (DHT-B), alone and in combination, using silastic tubing for 2-7 months. The results showed that DHT-B alone induced proliferation of uterine endometrial epithelium and myometrial smooth muscle cells, whereas E2 alone induced much more pronounced growth of endometrial epithelium without affecting smooth muscle cells. Combined treatment with E2+DHT-B caused an even more severe hyperplasia of endometrial epithelium and myometrial muscle cells, compared with the treatment with each hormone alone. Uterine leiomyomas were observed in 2 of 6 mice at 7 months of combined treatment but not in any of 6 or 7 mice receiving each single hormone. DHT-B alone induced growth and secretion of mammary ductal cells, as well as growth of mammary stroma. E2 alone stimulated much more pronounced growth of both ductal cells and alveolar cells and secretion of alveolar cells, but had no effect on mammary stroma. Treatment with both E2 and DHT-B caused more severe hyperplasia of mammary ducts and alveoli, compared to the treatment with each hormone alone. Intraductal hyperplasia occurred early and frequently in the E2+DHT-B- treated mice, but no mammary tumors were observed. These results suggest that E2 and DHT-B have synergistic effects on the growth of uterine endometrial epithelium and myometrial muscle cells, as well as mammary epithelial ducts and alveoli.

Androgens↗
PubMed2004

[Compariative study of mitochondrial tRNA gene sequence and secondary structure among fifteen Predatory birds].

Three major clusters of mitochondrial tRNA genes (tRNA(Ile) -tRNA(Gln) -tRNA(Met), tRNA(Trp)- tRNA(Ala) -tRNA(Asn)- tRNA(CYs) -tRNA(Tyr) and tRNA(His) tRNA(Ser)(AGY) -tRNA(Leu)(CUN) from 13 species of Predatory birds were amplified and sequenced. The length of these tRNA clusters was similar among species (212 approximately 214 bp, 353 approximately 362 bp, 205 approximately 208 bp, respectively), and 47% of the sequences were variable, 67% of which were involved in the loop regions. The stem regions were relatively conserved, and the variable base pairs were under the restriction of compensatory changes or G-U wobble pairing which could be regarded as mechanisms for maintaining a stable secondary structure. Maximum-parsimony (MP) and Neighbor joining (NJ) phylogenetic trees were constructed using all the tRNA gene sequences or stein-forming nucleotides with Caprimulgus indicus as outgroup. We found that the bootstrap values for branches of trees using the tRNA sequences were commonly higher than the others, therefore the phylogenetic relationship of Predatory birds reflected by these data may be closer to the truth. Phylogenetic analyses indicated that Accipitridae was closer to Strigidae instead of Falconidae, and the classification of Tytonidae was different from the conclusion from the previously morphological and DNA-DNA hybridization studies. By comparing the secondary structure among taxa we found that the characters of nucleotide insertions and deletions in some tRNA genes have synapomorphies, suggesting that these characters may be useful for resolving the phylogenetic relationship of different families in Predatory birds with higher phylogenetic performance.

Animals↗
PubMed2003

Tea polyphenol (-)-epigallocatechin-3-gallate inhibits DNA methyltransferase and reactivates methylation-silenced genes in cancer cell lines.

Hypermethylation of CpG islands in the promoter regions is an important mechanism to silence the expression of many important genes in cancer. The hypermethylation status is passed to the daughter cells through the methylation of the newly synthesized DNA strand by 5-cytosine DNA methyltransferase (DNMT). We report herein that (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol from green tea, can inhibit DNMT activity and reactivate methylation-silenced genes in cancer cells. With nuclear extracts as the enzyme source and polydeoxyinosine-deoxycytosine as the substrate, EGCG dose-dependently inhibited DNMT activity, showing competitive inhibition with a K(i) of 6.89 microM. Studies with structural analogues of EGCG suggest the importance of D and B ring structures in the inhibitory activity. Molecular modeling studies also support this conclusion, and suggest that EGCG can form hydrogen bonds with Pro(1223), Glu(1265), Cys(1225), Ser(1229), and Arg(1309) in the catalytic pocket of DNMT. Treatment of human esophageal cancer KYSE 510 cells with 5-50 microM of EGCG for 12-144 h caused a concentration- and time-dependent reversal of hypermethylation of p16(INK4a), retinoic acid receptor beta (RARbeta), O(6)-methylguanine methyltransferase (MGMT), and human mutL homologue 1 (hMLH1) genes as determined by the appearance of the unmethylation-specific bands in PCR. This was accompanied by the expression of mRNA of these genes as determined by reverse transcription-PCR. The re-expression of RARbeta and hMLH1 proteins by EGCG was demonstrated by Western blot. Reactivation of some methylation-silenced genes by EGCG was also demonstrated in human colon cancer HT-29 cells, esophageal cancer KYSE 150 cells, and prostate cancer PC3 cells. The results demonstrate for the first time the inhibition of DNA methylation by a commonly consumed dietary constituent and suggest the potential use of EGCG for the prevention or reversal of related gene-silencing in the prevention of carcinogenesis.

Adaptor Proteins, Signal Transducing↗
PubMed2003

Early NFkappaB activation is inhibited during focal cerebral ischemia in interleukin-1beta-converting enzyme deficient mice.

Our previous study demonstrated that the inhibition of interleukin-1beta (IL-1beta) reduces ischemic brain injury; however, the molecular mechanism of the action of IL-1 in cerebral ischemia is unclear. We are investigating currently the role of NFkappaB during focal cerebral ischemia, using mutant mice deficient in the interleukin-1 converting enzyme gene (ICE KO) in a middle cerebral artery occlusion (MCAO) model. Adult male ICE KO and wild-type mice (n = 120) underwent up to 24 hr of permanent MCAO. Cytoplasmic phospho-NFkappaB/p65 expression in ischemic brain was examined using Western blot analysis and immunohistochemistry. NFkappaB DNA-binding activity was detected using electrophoretic mobility shift assay (EMSA). Furthermore, ICAM-1 expression was examined in both the ICE KO and wild-type mice (WT). Western blot analysis and immunostaining showed that the level of cytosolic phosphorylated NFkappaB/p65 increased after 2 and 4 hr of MCAO in WT mice; however, NFkappaB/p65 was significantly reduced after MCAO in the ICE KO mice (P < 0.05). EMSA showed that NFkappaB DNA-binding activity increased after MCAO in WT mice; but this effect was reduced in the ICE KO mice. The number of ICAM-1-positive vessels in the ischemic hemisphere was greatly attenuated in the ICE KO mice (P < 0.05), which paralleled the results of immunohistochemistry. Our results demonstrate that NFkappaB phosphorylation is reduced in ICE KO mice, suggesting that ICE or IL-1 are involved in early NFkappaB phosphorylation. Because cerebral ischemia induced infarction is significantly reduced in ICE KO mice, we conclude that early NFkappaB phosphorylation plays a disruptive role in the ischemic process.

Animals↗
PubMed2003

Fingerprint analysis of Flos Carthami by capillary electrophoresis.

Capillary electrophoresis (CE) was employed in fingerprint analysis of Flos Carthami. A standardized procedure was used to develop the CE fingerprint. An electrophoretic profile of genuine Flos Carthami from Fengqiu, He'nan, China, was first established as the characteristic fingerprint. This profile was then used to identify and assess the consistency of the herb. A study with a limited number of samples from nine sources showed a fair consistency in their CE fingerprints with that of the genuine sample. Flos Carthami was well distinguished from Stigma Croci, a possible substitute in traditional Chinese medicine, and Flos Hemerocallis, a commercial adulterant, by comparing the fingerprints of each herb.

Asteraceae↗
PubMed2003

[Expression of human fibroleukin gene acute on chronic hepatitis B and its clinical significance].

OBJECTIVE: To investigate the mRNA and protein expressions of human fibroleukin gene (hfg12) in acute on chronic (AOC) hepatitis B and its clinical significance. METHODS: Liver tissues were obtained from 23 patients with AOC hepatitis B, 13 patients with chronic hepatitis, and 14 patients with cirrhosis to be examined histologically. Immunohistochemistry and in situ hybridization were used to detect the mRNA and protein expressions of hfg12 in the liver tissues. Double staining was used to the hfg12 positive samples to examine both the hfg12 and fibrin. Four specimens of liver tissue from normal donors were used as controls. RESULTS: Immunohistochemistry showed that hfg12 was expressed in the liver tissues of 21 out of the 23 patients with AOC hepatitis B (91.30%) and only one out of the 13 patients with chronic hepatitis (7.69%). In situ hybridization showed that hfg12 was expressed in the liver tissues of 13 out of he 23 patients with AOC hepatitis B and in none of the 27 patients with chronic hepatitis or cirrhosis. In patients with AOC hepatitis Kupffer's cell, CD68 positive, was numerous and big, mainly distributed in the necrosis areas. It was identified as the same of hfg12-expressing cells. CONCLUSION: High expression of hfg12 is one of the molecular mechanisms of necrosis of liver cells in AOC hepatitis.

Adolescent↗
PubMed2003

Signaling of human ciliary neurotrophic factor (CNTF) revisited. The interleukin-6 receptor can serve as an alpha-receptor for CTNF.

Human ciliary neurotrophic factor (CNTF) is a neurotrophic cytokine that exerts a neuroprotective effect in multiple sclerosis and amyotrophic lateral sclerosis. Clinical application of human CNTF, however, was prevented by high toxicity at higher dosages. Human CNTF elicits cellular responses by induction of a receptor complex consisting of the CNTF alpha-receptor (CNTFR), which is not involved in signal transduction, and the beta-receptors gp130 and leukemia inhibitory factor receptor (LIFR). Previous studies with rat CNTF demonstrated that rat CNTF is unable to interact with the human interleukin-6 alpha-receptor, whereas at high concentrations, it can directly induce a signaling heterodimer of human gp130 and human LIFR in the absence of the CNTF receptor. Here, we demonstrate that human CNTF cannot directly induce a heterodimer of human gp130 and LIFR. However, human CNTF can use both the membrane-bound and the soluble human IL-6R as a substitute for its cognate alpha-receptor and thus widen the target spectrum of human CNTF. Engineering a CNTFR-specific human CNTF variant may therefore be a prerequisite to improving the safety profile of CNTF.

Animals↗
PubMed2003

Determination of ferulic acid and adenosine in Angelicae Radix by micellar electrokinetic chromatography.

A micellar electrokinetic chromatography for determining ferulic acid and adenosine in Angelicae Radix was developed. A buffer solution composed of 50 mmol L(-1) borax, 10 mmol L(-1) sodium deoxycholate, and 2% methanol was found to be the most suitable electrolyte for the separation. The contents of ferulic acid and adenosine in Angelicae Radix were determined within 20 min. Good linearity between peak area ratio and the concentration was found in the range of approximately 20-320 microg mL(-1) for ferulic acid and about 10-160 microg mL(-1) for adenosine ( r >0.998), respectively. The recoveries were approximately 96.8-97.4% and 93.2-95.0%, and the RSD of this proposed method were 4.4% and 3.2% for ferulic acid and adenosine, respectively ( n=5). The contents of ferulic acid and adenosine in Angelicae Radix from different sources were determined.

Adenosine↗