Biomedical subjects

Yuan Li

Publications and source records attributed to Yuan Li.

At least 145 records · Page 8Linked to original sources

PubMed2004

[Establishment of a drug screening model for identifying up-regulator of human high density lipoprotein receptor].

OBJECTIVE: To establish a new drug screening model based on transcriptional regulation of human high density lipoprotein (HDL) receptor gene CD36 and LIMPII analogous-1 (CLA-1) for discovering up-regulator of this receptor. METHODS: The upstream regulatory sequence of CLA-1 was obtained by polymerase chain reaction. A recombinant reporter plasmid pGL3-CLAP was constructed by inserting the regulatory sequence upstream of luciferase gene of pGL3-Basic. Human hepatoma cell line BEL-7402 was transfected with pGL3-CLAP. Samples were detected by testing luciferase activity of transfected BEL-7402 cells in microtiter wells. RESULTS: The drug screening model was established and optimized. Significant difference was present between pGL3-CLAP and pGL3-Basic transfected BEL-7402 cells (P< 0.001), and coefficient of variation was less than 10%. After primary and secondary screening, 1 compounds and 3 fermentation extracts had up-regulating activities. CONCLUSION: This new drug screening model may be efficiently used to screen up-regulators of human HDL receptor expression, which might become lead compounds for new anti-atherosclerosis drugs.

CD36 Antigens↗

PubMed2004

[Correlation between single nucleotide polymorphism of insulin receptor gene with polycystic ovary syndrome].

OBJECTIVE: To investigate the correlation of C/T single nucleotide polymorphism at exon 17 in tyrosine kinase domain of insulin receptor gene with polycystic ovary syndrome (PCOS). METHODS: One hundred and twenty patients with PCOS (PCOS group) and 40 normal females (control group) were included and the 1058 site single nucleotide polymorphism at exon 17 of insulin receptor gene (INSR) was detected with polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The baseline parameters including levels of serum follicular stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), estradiol (E(2)), testosterone (T) and lipid, as well as the body mass index (BMI) and waist/hip ratio (WHR) were measured. Glucose tolerance and insulin releasing before and after loading with 75 g of glucose were also assayed. RESULTS: (1) BMI (25 +/- 4 vs. 23 +/- 3, P < 0.01), WHR (0.82 +/- 0.06 vs. 0.79 +/- 0.07, P < 0.05), LH [(9.2 +/- 6.1) U/L vs. (4.4 +/- 1.6) U/L, P < 0.01], T [(1.9 +/- 0.9) nmol/L vs. (1.0 +/- 0.6) nmol/L, P < 0.01] and E(2) [(205 +/- 119) pmol/L vs. (143 +/- 75) pmol/L, P < 0.01] of PCOS group were higher than those of control group. (2) The blood sugar and insulin levels of fasting, 30 min, 60 min, 120 min after glucose loading in obese PCOS (BMI >/= 25 kg/m(2)) were significantly higher than those in the non-obese PCOS (BMI < 25 kg/m(2)). (3) C/T single nucleotide polymorphism frequency at exon 17 of INSR in patients with PCOS was significantly higher than that in normal female (41% vs. 12.5%, P < 0.01). There was a significant difference between the frequency in non-obese PCOS (52.2%) and obese PCOS (25.5%, P < 0.01). (4) BMI in patients with T allele 23 +/- 3 of INSR single nucleotide polymorphism was lower than that with C allele (26 +/- 4, P < 0.05). CONCLUSIONS: (1) The body weight and gene single nucleotide polymorphism of INSR may play an important role in the occurrence of insulin resistance in patients with PCOS. (2) The 1058 site nucleotide polymorphism of insulin receptor gene is one of the susceptibility genes in patients with PCOS, especially in non-obese PCOS patients.

Adult↗

PubMed2004

Expression of mRNA for membrane-type 1, 2, and 3 matrix metalloproteinases in human laryngeal cancer.

OBJECTIVE: To investigate correlation of expressions of membrane-type 1, 2, and 3 matrix metalloproteinases (MT1, MT2, and MT3-MMP) to the invasion and metastases in laryngeal cancer. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the mRNA level of MT1, MT2, and MT3-MMP in 24 patients with laryngeal cancer. The relationships of these three MT-MMP expressions to clinicopathology were analyzed by statistics. RESULTS: The expressions of MT1, MT2, and MT3-MMP were significantly higher in laryngeal cancer tissues than those in para-tumorous tissues (P < 0.01) and had a close relationship with invasive depth (P < 0.05). But no significantly different expressions of these three MT-MMPs were found in different primary location and different histological grade of laryngeal cancer (P > 0.05). The expression of MT1-MMP was obviously higher in patients with metastatic lymph nodes than that in patients without metastatic lymph nodes (P < 0.05). CONCLUSION: MT1, MT2, and MT3-MMP play an important role in the progression of laryngeal cancer, and MT1-MMP may serve as a reliable marker in estimating invasive and metastatic potency of laryngeal cancer. Suppressing expressions of MT1, MT2, and MT3-MMP early may inhibit the invasion and metastases of laryngeal cancer.

Adult↗

PubMed2004

[Taxol based chemotherapy in the treatment of advanced gastric cancer].

OBJECTIVE: To evaluate the efficacy and toxicity of taxol-based chemotherapy in the treatment of advanced gastric cancer (AGC). METHODS: Twenty-nine patients with AGC treated with taxol-based protocols: taxol plus 5-fluouracil 17 patients, taxol plus cisplatin 10 patients, taxol plus epirubicin 2 patients. RESULTS: Twenty-six patients were evaluated for clinical response. There was no complete response, PR 10 (34.5%), SD 12 (41.4%), PD 4 (13.8%). The total response rate was 34.5%. The clinical beneficial response rate was 72.4% (21/29). Median time to progression (mTTP) was 5.8 months and median overall survival time was 9.3 months. The main side effects were: suppression of bone marrow in 26 patients (89.7%), alopecia in 25 (86.2%), myodynia and arthrodynia in 23 (79.3%). There was no death during the treatment. CONCLUSION: Taxol-based chemotherapy is an effective and well tolerated regimen in the treatment of AUC, which can relieve suffering and improve quality of life of the patients. It can be used as the second-line therapy for relapsed advanced gastric cancer.

Adult↗

PubMed2004

[Recombinant human bone morphogenetic protein-2 transform NIH3T3 fibroblast to osteo-like cells].

OBJECTIVE: To examine the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on NIH3T3 cells. METHODS: The NIH3T3 cells were cultured in DMEM with 50 microg/L rhBMP-2. The proliferation ability, alkaline phosphatase (ALP) activity and osteocalcin (OC) quantity of NIH3T3 cells were investigated. RESULTS: The cells showed decreased proliferation ability but enhanced ALP activity and OC quantity. CONCLUSION: 50 microg/L rhBMP-2 can transform NIH3T3 fibroblasts to osteo-like cells.

Alkaline Phosphatase↗

PubMed2004

[Expression and DNA binding activity of NF-kappaB in mucosal tissue of chronic rhinosinusitis].

OBJECTIVE: To study the expression and activation of nuclear factor-kappa B (NF-kappaB) in mucosa of rhinosinusitis. METHODS: The expressions of NF-kappaB p50 and p65 in the mucosa from 18 patients and 10 norms were detected with the method of immunohistochemistry. The activation of DNA-binding proteins which was labelled with 32P-radiolabeled oligonucleotide probe for NF-kappaB was detected with electrophoretic mobility shift assays (EMSA) in mucosa. RESULTS: Plasma of epithelial and glandular cells displayed a strongly positive staining reaction to p65, and nucleus displayed a strongly positive staining reaction to p50 (7.8%-52.1%). There was significantly difference (chi2 = 22.917, P < 0.01). The DNA-binding proteins activity of 18 samples from patients with chronic rhinosinusitis (28.14 +/- 16.71) was stronger than that (9.28 +/- 2.84) in normal subjects (t = 4.56, P < 0.05). CONCLUSIONS: The expression and DNA-binding proteins activity of NF-kappaB was enhanced. It indicated that NF-kappaB was activated in mucosal inflammation of chronic rhinosinusitis.

Case-Control Studies↗

PubMed2004

[The cryopreservation of human oocytes at different maturity stages].

OBJECTIVE: To examine the ultrastructure changes and the effects of different sucrose concentrations on the developmental potential of human frozen-thawed oocytes at different maturity stages. METHODS: Oocytes at different maturity stages collected from polycystic ovarian syndrome patients were involved in the study. Different sucrose concentrations (0.1, 0.2 or 0.3 mol/L) were used to study the developmental potential of the frozen-thawed oocytes. Non-frozen and frozen-thawed different maturity oocytes were processed for transmission electron microscopy observation. RESULTS: The results revealed that the mitochondria and the vesicles in the immature oocytes cytoplasm were fewer than those in the mature oocytes without regular distribution. Electron density of the mitochondria and distribution of the vesicles in the mature oocytes changed with the cryopreservation. No remarkable change was produced in the immature oocytes between non-frozen and frozen-thawed oocytes. Cryopreserving with 0.2 mol/L sucrose resulted in perfect development potential for both mature and immature oocytes than that with 0.1 mol/L. Study involving 0.3 mol/L sucrose in the cryoprotectant resulted in higher survival rate and clinical pregnancies. CONCLUSION: The results suggest that sucrose concentration of 0.3 mol/L in the cryoprotectant solution is efficient in freezing oocytes with slow-freezing method. Cryopreservation with slow-freezing method could produce ultrastructure changes in the human oocytes.

Cell Survival↗

PubMed2004

[Immunohistochemical diagnosis of fungus ball in paranasal sinuses].

OBJECTIVE: To study the pathogens of fungus balls in paranasal sinuses and establish an immunohistochemical test by which the main opportunistic fungi could be identified. METHODS: Twenty-five patients with fungal balls were treated by surgical removal of the fungus ball in the infected sinuses. The pathogenic fungi on the specimens were identified by means of routine PAS and immunohistochemical staining methods, and the sensitivity of the two methods were compared. RESULTS: The most commonly infected sinus was the maxillary sinus, followed by sphenoid sinus. Pathogens of fungal balls were found to be aspergillus (92%, 23/25) and candida 2 cases (8%). Aspergillus and candida albicans in infected sinuses could be specifically identified by immunostainning. There was no statistically significant differences of sensitivity between immunostainning and PAS stain. CONCLUSIONS: The main pathogen of the fungus ball was aspergillus. Immunostainning was a rapid and reliable method to identify fungi in infected tissues of paranasal sinuses. It should be widely used in the diagnosis of fungal sinusitis.

Adult↗

PubMed2004

[The positive effect of transforming growth factor beta on ectomesenchymal stem cells of embryonic facial processes differentiating to smooth muscle cells].

OBJECTIVE: To investigate the effect of transforming growth factor beta (TGF-beta) on ectomesenchymal stem cells differentiating to smooth muscle cells. METHODS: 60 pmol/L TGF-beta was added to the ectomesenchymal stem cells of embryonic facial processes. Immunohistochemistry assay and image analysis were used to value the expression extent of a smooth muscle actin (alpha-SMA) and quantitative RT-PCR was used to value the quantity of alpha-SMA. RESULTS: 2 days later, about 95% cells in TGF-beta group and 65% cells in control group without differentiation inhibitor expressed alpha-SMA. Expression of alpha-SMA in TGF-beta group was stronger than that of control group after one and two days. Quantitative RT-PCR showed the quantity of alpha-SMA mRNA in treated group cells was more than that of in control group. CONCLUSION: Quantity of alpha-SMA in TGF-beta group is more than that of spontaneous differentiation group. TGF-beta has positive effect on ectomesenchymal stem cells differentiating to smooth muscle cells.

Actins↗

PubMed2004

[Studies on chemical constituents from branch of Trema angustifolia].

OBJECTIVE: To study the chemical constituents from the branch of Trema angustifolia. METHOD: The compounds were isolated by silica gel column chromatography, and their structures were elucidated by means of spectral analysis. RESULT: Six compounds were identified as beta-sitosterol (I), viminalol (II), acetylursolic acid (III), oleanolic acid (IV), paprazine (V), moupinamide (VI). CONCLUSION: All the compounds were isolated from this plant for the first time.

Chromatography, Gel↗

PubMed2004

[Expression of the human soluble interleukin 4 receptor in methylotropic yeast].

Interleukin-4 (IL-4) is a pleiotropic cytokine which plays a pivotal role in shaping immune responses. IL-4 mediates important proinflammatory functions in asthma, including the IgE isotype switch. IL-4 exerts its biological effects through binding to its receptor (IL-4R) complex, with the alpha chain as the high affinity binding subunit. Soluble IL-4R lacks the transmemberane and cytoplasmic domains, so it cannot induce cellular activation. By acting as a decoy to circulating IL-4 and neutralize its activity, its high specificity and affinity make it ideal as an IL-4 antagonist. Some companies have embarked the clinical research for asthma treatment with the sIL-4R and the result revealed well therapeutic effect. With RNA extracted from human monocyte as the template, The sIL-4R cDNA encoding the extracellular domain of IL-4R a chain was obtained by RT-PCR. Compared with the sIL-4R encoding sequence in GenBank, the nucleotide sequencing analysis indicated that there was a A-->G mutation at 148bp and the mutation caused Ile-->Val at 50th amino acid. According to the references, numerous polymorphisms have been identified in the IL-4R gene and the Ile50Val was the only known extracellular variant of human IL-4R. Then the recombinant vector pPIC9K/sIL-4R was constructed, linearized and introduced into Pichia pastoris GS115 by electroporation. The recombinant sIL-4R was identified by SDS-PAGE, Western blot and Ligand binding blot. The SDS-PAGE and Western blot analysis showed that the apparent molecular weight of expressed sIL-4R was about 30kD. And the Ligand binding blot analysis indicated the expressed sIL-4R had the biological activity. The sIL-4R, which had the biological activity, was successfully secretorily expressed in the Pichia pastoris (GS 115).

Genetic Vectors↗

PubMed2003

A dominant negative mutant of TLK1 causes chromosome missegregation and aneuploidy in normal breast epithelial cells.

BACKGROUND: In Arabidopsis thaliana, the gene Tousled encodes a protein kinase of unknown function, but mutations in the gene lead to flowering and leaf morphology defects. We have recently cloned a mammalian Tousled-Like Kinase (TLK1B) and found that it phosphorylates specifically histone H3, in vitro and in vivo. We now report the effects that overexpression of a kinase-dead mutant of TLK1B mediates in a normal diploid cell line. RESULTS: Expression of a kinase-dead mutant resulted in reduction of phosphorylated histone H3, which could have consequences in mitotic segregation of chromosomes. When analyzed by FACS and microscopy, these cells displayed high chromosome number instability and aneuploidy. This phenomenon was accompanied by less condensed chromosomes at mitosis; failure of a number of chromosomes to align properly on the metaphase plate; failure of some chromosomes to attach to microtubules; and the occasional presentation of two bipolar spindles. We also used a different method (siRNA) to reduce the level of endogenous TLK1, but in this case, the main result was a strong block of cell cycle progression suggesting that TLK1 may also play a role in progression from G1. This block in S phase progression could also offer a different explanation of some of the later mitotic defects. CONCLUSIONS: TLK1 has a function important for proper chromosome segregation and maintenance of diploid cells at mitosis in mammalian cells that could be mediated by reduced phosphorylation of histone H3 and condensation of chromosomes, although other explanations to the phenotype are possible.

Aneuploidy↗

PubMed2003

Evaluation of the cancer chemopreventive potency of dithiolethione analogs of oltipraz.

Oltipraz and related dithiolethiones constitute an important class of chemopreventive agents that enhance the expression of carcinogen detoxication and antioxidant genes. Dose-response studies were undertaken to characterize the cancer chemopreventive activities of several dithiolethiones that are at least as active as oltipraz as inducers. Inhibition of formation of pre-neoplastic lesions and formation of DNA adducts in livers of rats exposed to aflatoxin B1 (AFB1) was monitored. In the tumorigenesis experiment, the dithiolethiones were orally gavaged 3 days/week for 3 successive weeks and at four doses ranging from 0.03 to 0.3 mmol/kg body wt. AFB1 was gavaged beginning 1 week after the start of the dithiolethiones and for two successive weeks. The burden of AFB1-induced putative pre-neoplastic lesions (glutathione S-transferase-placental isoform positive foci) was quantified by light microscopy. Reduction in AFB-DNA adduct burden was assessed 24 h following the first dose of AFB1. Both the parent 1,2-dithiole-3-thione (D3T) and its 5-tert-butyl derivative were more potent inhibitors than oltipraz against these endpoints, while two of the seven tested analogs were slightly less inhibitory. D3T, the most potent dithiolethione of this series, was examined by microarray analysis for induction of hepatic genes at an intermediate chemopreventive dose (0.1 mmol/kg). Transcript levels of eight genes, including two known to detoxify aflatoxin, namely, glutathione S-transferase A5 (GSTA5) and AFB1 aldehyde reductase (AFAR) were elevated. Western analysis indicated that induction of hepatic GSTA5 and AFAR were directly related to the dose of D3T. At the highest dose of D3T (0.3 mmol/kg), protein levels of GSTA5 and AFAR were induced by 7- and 27-fold, respectively. While efficacy in humans has yet to be tested, D3T is clearly more potent than oltipraz and serves as a useful molecular probe for determining the key events associated with protection by this class of agents.

Aflatoxin B1↗

PubMed2003

Preparation and characterization of nanoaggregates of poly(ethylene oxide)-b-polymethacrylate and poly-L-lysine.

Poly(ethylene oxide)-b-polymethacrylate (PEO-b-PMA), one of the double-hydrophilic block copolymers, has proved to the form nanoaggregates with poly-L-lysine (PLS). This was confirmed by turbidimetry, zeta-potential measurements, and dynamic light scattering. The nanoaggregate formation is induced by electrostatic charge neutralization of the PMA block with PLS. The properties of the aggregates are affected by PLS concentration as well PEO-b-PMA concentration. The aggregates have potential applications in biomedical science.

Ethylene Oxide↗

PubMed2003

Modulation of ANP-C receptor signaling by arginine-vasopressin in A-10 vascular smooth muscle cells: role of protein kinase C.

We have previously shown that pretreatment of A-10 vascular smooth muscle cells (VSMC) with angiotensin II (Ang II) attenuated atrial natriuretic peptide receptor-C (ANP-C)-mediated inhibition of adenylyl cyclase without altering [125I]ANP binding. In the present studies, we have investigated the modulation of ANP-C receptor signaling by arginine-vasopressin (AVP). Pretreatment of A-10 VSMC with AVP for 24h resulted in a reduction in ANP receptor binding activity by about 50% (B(max); control cells, 22.9+/-2.5 fmol/mg protein, AVP-treated cells, 11.4+/-1.2 fmol/mg protein). In addition, the expression of ANP-C receptor as determined by immunoblotting was also decreased by about 50% by AVP treatment, which was prevented by GF109203X, an inhibitor of protein kinase C (PKC). The decreased expression of ANP-C receptor was reflected in an attenuation of ANP-C receptor-mediated inhibition of adenylyl cyclase. C-ANP(4-23) [des(Gln(18),Ser(19),Gln(20),Leu(21),Gly(22))ANP(4-23)-NH(2)], a ring deleted peptide of ANP that interacts specifically with ANP-C receptor, inhibited adenylyl cyclase activity by about 30% in control cells, which was completely attenuated in AVP-treated cells. This attenuated inhibition was significantly restored by GF 109203X. In addition, AVP treatment augmented the levels of Gialpha-2 and Gialpha-3 proteins; however, the Gi functions were completely attenuated. The increased expression of Gialpha proteins induced by AVP was inhibited by GF109203X as well as by actinomycin D treatments. In addition, AVP treatment also enhanced the expression of Gsalpha protein and Gsalpha-mediated stimulation of adenylyl cyclase by GTPgammaS, N-ethylcarboxamide adenosine (NECA), and forskolin (FSK), whereas the levels of Gbeta were not altered by AVP treatment. These results indicate that AVP-induced PKC signaling may be responsible for the down-regulation of ANP-C receptor that results in the attenuation of C-ANP(4-23)-mediated inhibition of adenylyl cyclase activity, and suggest a cross-talk between vasopressin V(1) and ANP-C receptor-mediated signaling pathways.

Adenylyl Cyclases↗

PubMed2003

Transcription start regions in the human genome are favored targets for MLV integration.

Factors contributing to retroviral integration have been intractable because past studies have not precisely located genomic sites of proviruses in sufficient numbers for significant analysis. In this study, 903 murine leukemia virus (MLV) and 379 human immunodeficiency virus-1 (HIV-1) integrations in the human genome were mapped. The data showed that MLV preferred integration near the start of transcriptional units (either upstream or downstream) whereas HIV-1 preferred integration anywhere in the transcriptional unit but not upstream of the transcriptional start. Defining different integration site preferences for retroviruses will have important ramifications for gene therapy and may aid in our understanding of the factors directing the integration process.

Child↗

PubMed2003

Morphine enhances HIV infection of neonatal macrophages.

Perinatal transmission of HIV accounts for almost all new HIV infections in children. There is an increased risk of perinatal transmission of HIV with maternal illicit substance abuse. Little is known about neonatal immune system alteration and subsequent susceptibility to HIV infection after morphine exposure. We investigated the effects of morphine on HIV infection of neonatal monocyte-derived macrophages (MDM). Morphine significantly enhanced HIV infection of neonatal MDM. Morphine-induced HIV replication in neonatal MDM was completely suppressed by naltrexone, the opioid receptor antagonist. Morphine significantly up-regulated CCR5 receptor expression and inhibited the endogenous production of macrophage inflammatory protein-1beta in neonatal MDM. Thus, morphine, most likely through alteration of beta-chemokines and CCR5 receptor expression, enhances the susceptibility of neonatal MDM to HIV infection, and may have a cofactor role in perinatal HIV transmission and infection.

Analgesics, Opioid↗

PubMed2003

Identification and characterization of a new exopolysaccharide biosynthesis gene cluster from Streptomyces.

We report the identification and characterization of the ste (Streptomyces eps) gene cluster of Streptomyces sp. 139 required for exopolysaccharide (EPS) biosynthesis. This report is the first genetic work on polysaccharide production in Streptomyces. To investigate the gene cluster involved in exopolysaccharide 139A biosynthesis, degenerate primers were designed to polymerase chain reaction amplify an internal fragment of the priming glycosyltransferase gene that catalyzes the first step in exopolysaccharide biosynthesis. Screening of a genomic library of Streptomyces sp. 139 with this polymerase chain reaction product as probe allowed the isolation of a ste gene cluster containing 22 open reading frames similar to polysaccharide biosynthesis genes of other bacterial species. Involvement of the ste gene cluster in exopolysaccharide biosynthesis was confirmed by disrupting the priming glycosyltransferase gene in Streptomyces sp. 139 to generate non-exopolysaccharide-producing mutants.

Amino Acid Sequence↗