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Yang Li

Publications and source records attributed to Yang Li.

214 records · Page 12Linked to original sources
PubMed2002

Cellular uptake, distribution, and stability of 10-23 deoxyribozymes.

The cellular uptake, intracellular distribution, and stability of 33-mer deoxyribozyme oligonucleotides (DNAzymes) were examined in several cell lines. PAGE analysis revealed that there was a weak association between the DNAzyme and DOTAP or Superfect transfection reagents at charge ratios that were minimally toxic to cultured cells. Cellular uptake was analyzed by cell fractionation of radiolabeled DNAzyme, by FACS, and by fluorescent microscopic analysis of FITC-labeled and TAMRA-labeled DNAzyme. Altering DNAzyme size and chemistry did not significantly affect uptake into cells. Inspection of paraformaldehyde-fixed cells by fluorescence microscopy revealed that DNAzyme was distributed primarily in punctate structures surrounding the nucleus and that substantial delivery to the nucleus was not observed up to 24 hours after initiation of transfection. Incubation in human serum or plasma demonstrated that a 3'-inversion modification greatly increased DNAzyme stability (t(1/2) approximately 22 hours) in comparison to the unmodified form (t(1/2) approximately 70 minute). The 3'-inversion-modified DNAzymes remained stable during cellular uptake, and catalytically active oligonucleotide could be extracted from the cells 24 hours posttransfection. In smooth muscle cell proliferation assay, the modified DNAzyme targeting the c-myc gene showed a much stronger inhibitory effect than did the unmodified version. The present study demonstrates that DNAzymes with a 3'-inversion are readily delivered into cultured cells and are functionally stable for several hours in serum and within cells.

Base Sequence↗
PubMed2002

Characterization of human ocular mucin secretion mediated by 15(S)-HETE.

PURPOSE: The eicosanoid 15-(S)-hydroxy-5,8,11,13-eicosatetraenoic acid [15(S)-HETE] is reported to stimulate mucin production in both airway and ocular surface epithelia. The current study was undertaken to evaluate the effects of 15(S)-HETE on secretion of specific ocular mucins by human conjunctiva. METHODS: Segments of human bulbar conjunctival tissue were incubated with 15(S)-HETE (1-1000 nM) for 30 minutes at 37 degrees C. Secretion of human ocular mucins MUC1, MUC2, MUC4, and MUC5AC into the incubation media was measured by dot-blot immunoassay using antibodies directed to unique mucin polypeptide epitopes. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting were used to verify the specificity of anti-mucin antibody binding and to investigate the presence of MUC1 mucin in human tears. RESULTS: 15(S)-HETE (10(-8)-10(-6) M) stimulated secretion of conjunctival mucins in a concentration-dependent manner. Significant increases in total mucin secretion were observed at 10(-7) M 15(S)-HETE with a maximum response (>50% increase above controls) at 10(-6) M. Results of immunoassays showed that 15(S)-HETE differentially stimulates secretion of MUC1 mucin with no detectable effects on MUC2, MUC4, or MUC5AC release. Western analysis of tear samples from human volunteers indicated that MUC1 is a component of the preocular tear film. CONCLUSIONS: The results demonstrate that 15(S)-HETE is a selective secretogogue for MUC1 in isolated human conjunctival tissue. Although the biochemical mechanism(s) and cellular origins of MUC1 secretion remain to be established, the ubiquitous expression of MUC1 in corneal and conjunctival epithelia and its presence in human tears suggest that secreted MUC1 may contribute to the mucin layer that coats and protects the ocular surface.

Adult↗
PubMed2002

Fluorescence spectroscopy as a biomarker in a cell culture and in a nonhuman primate model for ovarian cancer chemopreventive agents.

OBJECTIVE: The objective of this study was to compare the effects of chemopreventive agents on natural fluorescence emission of ovarian cells in a cell culture and in a primate model as a feasibility trial to monitor drug activity. METHODS: Fluorescence emission spectra were collected from normal (NOE) and immortalized ovarian surface epithelial cells at 290, 360, and 450 nm excitation. Redox potentials were calculated and compared to % apoptosis and cell survival. Fluorescence emission spectra were collected from 18 female rhesus macaques receiving fenretinide [N-(-hydroxyphenyl)retinamide (4-HPR)] orally and/or oral contraceptive pills (OCP) or no medication. Fluorescence intensities and redox ratios were compared using a two-tailed Student's t test. RESULTS: Apoptosis and cell survival correlated with fluorescence emission consistent with metabolically active proteins [flavin adenine dinucleotide (FAD) and nicotinamide adenine dinucleotide (NAD(P)H)] and the resulting redox ratio in cells grown with 4-HPR. The 4-HPR consistently inhibited cell survival in a dose dependent manner. Degree of correlation varied between different cell lines. In primates receiving 4-HPR, fluorescence emission was increased at 450 nm excitation, 550 nm emission consistent with FAD presence, whereas those receiving OCP showed decreased emission at 350 nm excitation, 450 nm emission consistent with decreased NAD(P)H presence. Redox ratios were increased by both drugs. CONCLUSIONS: Fluorescence intensity and redox ratio appear to be altered by 4-HPR treatment in vivo and in cell culture and by OCP in vivo. Fluorescence intensity may be useful to monitor chemopreventive agents in clinical trials.

Animals↗
PubMed2002

Role of ICAM-1 in chronic hepatic allograft rejection in the rat.

The pathogenesis of hepatic allograft rejection remains unclear. We aimed to clarify the early role of intercellular adhesion molecule-1 (ICAM-1)-mediated cell recruitment in chronic hepatic rejection. Liver transplantation was performed from Lewis to Lewis rats (isograft controls) and from Lewis to Brown Norway rats (allograft rejection group). The allografted rats were treated with either ICAM-1 antisense oligonucleotides (10 mg. kg(-1). day(-1) x 6 days ip) or a control preparation (either ICAM-1 missense oligonucleotide or normal saline). Hepatic leukocyte recruitment in vivo was studied on day 6 by using intravital microscopy. Liver histology, biochemistry, and survival rates were also examined. Leukocyte adhesion in terminal hepatic venules was significantly increased in the rejection group compared with isograft controls. Antisense ICAM-1 in the allografted group effectively reduced leukocyte adhesion. Histology and liver chemistry were less deranged in the antisense-treated groups compared with control-treated allografted rats. In the allograft groups, survival was significantly prolonged in the antisense-treated rats (42.3 +/- 1.2 days) compared with the controls (25.2 +/- 2.7 days). These results showed that early leukocyte recruitment in the hepatic microvasculature of rejecting allografts is ICAM-1 dependent and suggest that impacting on early cell recruitment can significantly ameliorate chronic rejection.

Animals↗
PubMed2002

Effects of benzyltetrahydropalmatine on potassium currents in guinea pig and rat ventricular myocytes.

AIM: To investigate the effects of benzyltetrahydropalmatine (BTHP) on rapidly activating component (I(Kr)), slowly activating component (I(Ks)) of delayed rectifier potassium current, inward rectifier potassium current (I(K1)), and transient outward potassium current (I(to)) in single ventricular myocytes. METHODS: Whole-cell patch clamp technique was used to record ionic currents. RESULTS: (1) BTHP 30 micromol/L reduced I(Kr) and I(Kr,tail) by 31 %+/-4 % and 36 %+/-5 % (n=6, P <0.01), respectively and inhibited I(Ks) and I(Ks,tail) by 40 %+/-6 % and 45 %+/-5 % (n=7, P <0.01), respectively. I(Kr) and I(Ks) were blocked by BTHP 1-100 micromol/L in a concentration-dependent fashion (IC50 value was 13.5 micromol/L and 95 % confidence limit: 11.2-15.8 micromol/L for I(Kr), 9.3 micromol/L and 95 % confidence limit: 7.8-11.8 micromol/L for I(Ks), respectively). (2) BTHP 5 micromol/L inhibited I(to) by 63 %+/-6 % (n=6, P <0.01). BTHP 1-100 micromol/L reduced I(to) in a concentration-dependent manner (IC50 value was 3.6 micromol/L and 95 % confidence limit: 2.9-4.3 micromol/L). (3) BTHP 200 micromol/L did not affect I(K1). CONCLUSION: BTHP inhibited I(Kr), I(Ks), and I(to), but not I(K1). The antiarrhythmic effects of BTHP may be mainly due to its blockade on potassium channels.

Animals↗
PubMed2002

Influence of several uropathogenic microorganisms on human sperm motility parameters in vitro.

AIM: The effects of certain uropathogenic microorganisms (Neisseria gonorrhoeae, Staphylococcus aureus, Staphylococcus epidermidis and Mycobacterium tuberculosis) on human sperm motility characteristics were studied in vitro. METHODS: In 10 healthy fertile men, ejaculates were aseptically obtained by masturbation and with a swim-up technique, a sperm suspension of high motility and purity was obtained. Several uropathogenic bacteria were obtained from outpatients with genitourinary tract infections. The sperm suspension was incubated with the pathogens at a bacteria: sperm ratio of 50:1 at 37deg. The sperm mobility parameters were estimated with a computer-assisted sperm analyzer (CASA) provided with a multiple-exposure photography system (Madi Corp., Zhejiang, China). Measurements were carried out at 0, 2 and 4 hours of incubation. RESULTS: Staphylococcus aureus significantly decreased the sperm motility and viability, but Staphylococcus epidermidis, Mycobacterium tuberculosis and Neisseria gonorrhoeae did not. CONCLUSION: Staphylococcus aureus has an inhibitory effect on human sperm motility in vitro.

Gonorrhea↗
PubMed2002

Effect of retinoblastoma gene on human osteosarcoma cell line OS732.

OBJECTIVE: To investigate the effect of growth suppression and gap junctional intercellular communication (GJIC) on osteosarcoma cell line OS732 transduced with the exogenous N-terminal truncated retinoblastoma (Rb) gene. METHODS: Recombinant eukaryotic expression plasmid harbouring 1.65 kb Rb gene was constructed and transduced into OS732 cells. Rb mRNA expression was detected by RT-PCR and Northern blot. The cell count, cell cycle analysis and soft agar colony formation test were used to observe growth features. RT-PCR and Lucifer yellow dye transfer were carried out to measure GJIC. RESULTS: Both exogenous and endogenous Rb gene could be detected in OS732 cell transduced with the N-terminal truncated Rb gene. Compared with the parental cells, change in morphology of Rb-transduced cells were found; growth rate decreased; amount of colony formation reduced; cell cycle arrested at G(0)/G(1) checkpoint; Connexin43 expression and GJIC enhanced. CONCLUSIONS: The malignant phenotype of OS732 is inhibited and GJIC is increased by transduction of N-terminal truncated Rb gene.

Bone Neoplasms↗
PubMed2002

[Influence of protein kinase C on motility and acrosome reaction of sperm].

Protein kinase C (PKC) is localized in the equatorial segment and the principal piece of the tail of spermatozoa. Activator of PKC results in increasing flagellar motility of sperm that is blocked by PKC inhibitors such as staurosporine. A good correlation (r = 0.9, P < 0.001) is found between the content of PKC in sperm and sperm motility. Zona pellucida (ZP) stimulates the spermatozoa binding the acrosome reaction resulting in the release of hydrolytic enzymes and in the exposure of new membrane domains. ZP binding to receptors in the plasma membrane can regulate adenyl cyclase (AC) leading to elevation of cAMP and protein kinase A (PKA) activation. The PKA activates a voltage-dependent Ca2+ channel in the outer acrosomal membrane which releases Ca2+ from the interior of the acrosome to the cytosol. Activation of the PLC resulted from the rise in Ca2+ hydrolyze phosphatidyl inositol bisphosphate. The product activate PCK to open a voltage-dependent Ca2+ channel (L) in the plasma membrane, leading to the second (II) Ca2+ higher increase which result in membrane fusion and acrosome reaction. It is proposed that PKC would be involved in the regulation of motility and acrosome reaction of sperm.

Acrosome Reaction↗
PubMed2002

[Study on solid phase extraction spectrophotometric determination of copper(II) with 2-(4-antipyrinylazo)-5-dimethylaminoaniline].

Based on the color reaction of 2-(4-Antipyrinylazo)-5-Dimethylaminoaniline (ADA) with copper (II) and the solid phase extraction of its colored complex with Waters Porapak(r) Sep-Park-C18 cartridge, a new method for the determination trace amount of copper(II) was studied. In the medium of Tween-80 and presence of pH = 4.5 buffer solution, ADA can react with copper (II) to form a stable 2:1 complex. The colored complex can extracted by Porapak(r) Sep-Park-C18 cartridge and eluted by ethanol contain 1% of acetic acid, then can be determined by spectrophotometer at 530 nm. Beer's law is obeyed in range of 0.05(1.0(g/ml. This method can be applied to the determination trace amount of copper in water with satisfactory results.

Aniline Compounds↗
PubMed2002

[Effect of free-air CO2 enrichment on soil microbe in paddy field].

Utilizing FACE research site in Anzhen of Wuxi, the effect of CO2 concentration increasing on soil microbe was studied in a paddy field under the condition of local cultivation, irrigation and fertilization. The results showed that soil respiration intensity was 31.88 ml.kg-1 and bacteria number was 1.51 x 10(6) ind.g-1 dry soil in FACE area, which were greater than those in control area (soil respiration intensity 27.83 ml.kg-1, bacteria number was 1.25 x 10(6) ind.g-1 dry soil, but the differences were not significant.

Agriculture↗
PubMed2002

Effects of benzyltetrahydropalmatine on the rapidly activating component of delayed rectifier potassium current in guinea pig ventricular myocytes.

AIM: To investigate the effect of benzyltetrahydropalmatine (BTHP) on the rapidly activating component of delayed rectifier K+ current (Ikr) in single guinea pig ventricular myocytes. METHODS: Whole-cell patch clamp technique was used to record Ikr. RESULTS: Ikr was blocked by 1-100 mumol.L-1 BTHP in concentration-, voltage-, and specifically frequency-dependent fashion, with IC50 of 13.5 mumol.L-1 (95% confidence range: 11.2-15.8 mumol.L-1). 30 mumol.L-1 BTHP reduced Ikr and Ikr.tail by (31 +/- 4)% and (36 +/- 5)% (n = 6, P < 0.01), respectively. The time constant for deactivation (tau') of the tail current was decreased by 30 mumol.L-1 BTHP from (238 +/- 16) ms to (196 +/- 14) ms, while drug had no any effect on the time constant for activation (tau) of Ikr,tail. CONCLUSION: BTHP inhibited Ikr in a frequency-dependent fashion.

Animals↗
PubMed2002

[Influence of dibutyryl cyclic adenosine monophosphate on motility of sperm].

OBJECTIVES: To investigate the influence of cAMP/PKA signal transduction on human sperm motility, and to study the effect of dibutyryl cyclic adenosine monophosphate dibutyryl cyclic adenosine monophosphate (dbcAMP) on human sperm motility in vitro. METHODS: Sperm aseptically obtained by masturbation and prepared by swim-up technique from 10 healthy fertile men were incubated with different concentrations of dbcAMP. Measurement of mobility were carried out at 20, 30, and 60 min in all specimens. RESULTS: The sperm treated with dbcAMP showed a significant increase in sperm progressive motility and the percentage of motile cells. The effect seemed enhanced with the increasing of dbcAMP concentration. VSL and VCL were not affected by dbcAMP. CONCLUSIONS: dbcAMP can activate the mobility of human sperm in vitro.

Adult↗
PubMed2002

[Optimization of parameters of exogene transfection of bovine fetal fibroblasts in vitro mediated by liposome].

pEGFP-C1 eucaryon expression vector was successfully transfected by liposome into bovine fetal fibroblasts. We investigated the effect of parameter such as the dose of DNA and liposome,number of cell transfected and exposure time of the cell to the DNA-liposome complexes. It was indicated that GFP (green fluorescent protein) expression was enhanced as the dose of DNA and liposome increased and on decline as the exposure time was prolonged. The improvement of transfection efficiency depent on the suitable cell number.

English Abstract↗
PubMedDate not supplied

Novel biodegradable aliphatic poly(butylene succinate-co-cyclic carbonate)s bearing functionalizable carbonate building blocks: II. Enzymatic biodegradation and in vitro biocompatibility assay.

In a previous study, we have reported chemical synthesis of novel aliphatic poly(butylene succinate-co-cyclic carbonate) P(BS-co-CC)s bearing various functionalizable carbonate building blocks, and this work will continue to present our new studies on their enzymatic degradation and in vitro cell biocompatibility assay. First, enzymatic degradation of the novel P(BS-co-CC) film samples was investigated with two enzymes of lipase B Candida Antartic (Novozyme 435) and lipase Porcine Pancreas PPL, and it was revealed that copolymerizing linear poly(butylene succinate) PBS with a functionalizable carbonate building block could remarkably accelerate the enzymatic degradation of a synthesized product P(BS-co-CC), and its biodegradation behavior was found to strongly depend on the overall impacts of several important factors as the cyclic carbonate (CC) comonomer structure and molar content, molar mass, thermal characteristics, morphology, the enzyme-substrate specificity, and so forth. Further, the biodegraded residual film samples and water-soluble enzymatic degradation products were allowed to be analyzed by means of proton nuclear magnetic resonance (1H NMR), gel permeation chromatograph (GPC), differential scanning calorimeter (DSC), attenuated total reflection FTIR (ATR-FTIR), scanning electron microscope (SEM), and liquid chromatograph-mass spectrometry (LC-MS). On the experimental evidences, an exo-type mechanism of enzymatic chain hydrolysis preferentially occurring in the noncrystalline domains was suggested for the synthesized new P(BS-co-CC) film samples. With regard to their cell biocompatibilities, an assay with NIH 3T3 mouse fibroblast cell was conducted using the novel synthesized P(BS-co-CC) films as substrates with respect to the cell adhesion and proliferation, and these new biodegradable P(BS-co-CC) samples were found to exhibit as low cell toxicity as the PLLA control, particularly the two samples of poly(butylene succinate-co-18.7 mol % dimethyl trimethylene carbonate) P(BS-co-18.7 mol % DMTMC) and poly(butylene succinate-co-21.9 mol % 5-benzyloxy trimethylene carbonate) P(BS-co-21.9 mol % BTMC) were interestingly found to show much better cell biocompatibilities than the PLLA reference.

Animals↗
PubMedDate not supplied

Preparation and crystallization kinetics of new structurally well-defined star-shaped biodegradable poly(L-lactide)s initiated with diverse natural sugar alcohols.

This study presents syntheses, structural characterization, and crystallization kinetic investigation of new structurally well-defined star-shaped poly(l-lactide)s (PLLAs). First, a series of new 3- to 6-arm star-shaped PLLAs were synthesized through SnOct(2) catalyzed ring-opening polymerization of (l)-lactide with natural sugar alcohols of glycerol, erythritol, xylitol, and sorbitol as the favorable initiators. Subsequently, their chemical structures were characterized by means of GPC, NMR, and viscometer with respect to the star-shaped structures, demonstrating the well-defined arm structures as evidenced on the g(1/2)/g' values, where g and g' denote the ratios of mean-square radius of gyration and intrinsic viscosity of a star-shaped polymer to those of a linear structural reference with similar absolute molecular weight. Furthermore, spherulite morphologies and growth rates were studied by a polarized microscopy (POM) for the synthesized star-shaped PLLAs with different molecular weights, and it was found that the more arms of a star-shaped PLLA finally resulted in a lower spherulite growth rate. With regard to the crystallization kinetics of these star-shaped PLLAs, isothermal and nonisothermal crystallization were examined by differential scanning calorimeter (DSC). It was found that Avrami exponent n values of isothermal crystallization were almost independent of the isothermal crystallization temperature T(c) for different series of star-shaped PLLAs. In contrast, the values of Avrami exponent n were observed to strongly depend on the star-shaped structures with different arms, implying their distinct nucleation mechanisms, and the more arms of a star-shaped PLLA led to a slower isothermal crystallization rate. On the basis of a modified Avrami equation, new light was shed on the nonisothermal crystallization kinetics for the star-shaped PLLAs, and the activation energies were found to vary from 146.86 kJ/mol for the linear PLLA EG-3 to 221.23 kJ/mol of the star-shaped S-3, demonstrating much decreased crystallizabilities of star-shaped PLLAs with more arms.

Biodegradation, Environmental↗