Biomedical subjects

Jun Chen

Publications and source records attributed to Jun Chen.

At least 109 records · Page 6Linked to original sources

PubMed2006

[Influence of LY294002 on sperm motility in asthenozoospermia patients in vitro].

OBJECTIVE: To investigate the effects of LY294002, a phosphatidylinositol 3-kinase inhibition, on sperm motility in asthenozoospermia patients in vitro, and further analyze the possible molecular mechanism. METHODS: Sperm aseptically obtained by masturbation and prepared by swim-up technique from 10 patients with asthenozoospermia and 10 healthy fertile men were incubated with different concentrations of LY294002. Measurements of motility were carried out at 10, 30 and 60 min in all specimens by CASA. RESULTS: The sperm in asthenozoospermia patients treated with LY294002 showed a significant increase in sperm progressive motility, the percentage of motile cells, VSL and VAP. CONCLUSION: LY294002 can enhance the motility of sperm in asthenozoospermia patients in vitro.

Asthenozoospermia↗

PubMed2006

[RAPD analysis of Scutellaria baicalensis from different germplasms].

OBJECTIVE: To provide reference for breeding Scutellaria baicalensis from different germplasms,and to explore their genetic diversities and different strains. METHOD: The RAPD method was applied to the study on S. baicalensis from different germplasms by use of 14 random primers about 10 bp, and SAPD-analysis of 34 S. baicalensis from different germplasms was carried out by using the method of withingroups-linkage in SPSS 10.0. RESULTS: 14 among 115 primers were selected to amplify about 165 segments of DNA. Among them, 132 segments of DNA, 80.0% of the total, can represent genetic of diversities of S. baicalensis. According to RAPD analysis, 34 germplasms of S. baicalensis were classified into A, B, C and D categories. CONCLUSION: S. baicalensis from different germplasms shows abundant genetic diversities. Germplasms from Shandong like Mengyin 3, Menyin 2 and Pingyi have close distance (0.315) in genetic background, which can be chosen for breeding of cultivated. Though genetic characters are similar in the morphology, the geological distribution of S. baicalensis and its morphology have not certain correlation. The complex genetic background of S. baicalensis indicate that the work of the selective breeding and management for breeding of S. baicalensis have to be strengthened.

Breeding↗

PubMed2006

[Concentration calibration method of ambient trace-gas monitoring with tunable diode laser absorption spectroscopy].

Tunable diode laser absorption spectroscopy (TDLAS) is a new method to detect trace-gas qualitatively or quantificationally based on the scan characteristic of the diode laser used to obtain the absorption spectroscopy in the characteristic absorption region It needs to be combined with a long absorption path in the ambient trace-gas measurements. TDLAS is a new trace gas detective method developed with the combination of a tunable diode laser source and a long absorption path; it has significant advantages not only in the sensitivity but also in rapidity of response. It has been widely used in many atmospheric trace-gases detection, ground trace-gas detection and, gas leakage detection. On-line calibrating is necessary to most trace gas monitor, and in the present paper the authors introduced a simple and accurate method, analyzed it in the theory, and proved it's feasibility in the experiment.

English Abstract↗

PubMed2006

[Effects of voltage during anodization on titanium surface on cell attachment and spreading of osteoblasts].

PURPOSE: The effects of the voltage during anodic oxidation on cell attachment and spreading of human osteoblasts in early stage were investigated. METHODS: The samples were anodized in the electrolyte of 0.03 M calcium glycerophosphate (Ca-GP) mixed with 0.15 M calcium acetate (CA) under current density of 70 A/m2 and different voltages, 140V, 200V or 260V. The surface roughness of the specimens and the attachment and spreading of human osteoblasts in early stage were investigated. SPSS13.0 for windows was used for one-way ANOVA. RESULTS: The surface average roughness of cp Ti was significantly improved from 0.17 micro m to 0.23 micro m, 0.26 micro m, 0.33 micro m, respectively, by anodic oxidation with increased voltage (P<0.05). After 2 hours of cell culture, cell skeleton was reorganized and cell morphology became more irregular with the increase of anodizing voltages. Cell attachment on the specimens anodized under 260V was significantly higher than on the surface of cp Ti (P<0.05). CONCLUSION: The surface properties of cp Ti can be affected by anodic oxidation. The early cell attachment and spreading were enhanced with anodizing voltage.

Acetates↗

PubMed2006

[Study on separation and purification of anthraquinones in radix et rhizoma rhei by D301 macroporous resin].

OBJECTIVE: The parameters of absorption and purification of total anthraquinones in Radix Et Rhizoma Rhei by D301 macroporous resin were investigated in this paper. METHOD: HPLC was used to analyze the content of total anthraquinones in Radix Et Rhizoma with emodin as control. RESULT: The appropriate adsorption conditions were: concentration of extract 0.5 g x mL(-1); pH 9; flow rate 1 BV x h(-1). When the 75% ethanol was used as elution and the concentration of HCl was 0.1 mol x L(-1), and the flow rate was 1.0 BV x h(-1), the effect of desorption was satisfactory. CONCLUSION: D301 resin provided a good effect on the exchang and absorption of total anthraquinones in Radix Et Rhizoma.

Anthraquinones↗

PubMed2006

[Determination of fatty acids and organic acids in Ranunculus ternatus Thunb using GC-MS].

The determination of fatty acids and organic acids in Chinese medicinal plant Ranunculus ternatus Thunb using GC-MS was studied. The Ranunculus ternatus Thunb from Henan province was cut into less than 20 mesh pieces, then extracted by petroleum ether or ether in refluxing and esteried, and finally was determined using GC-MS. The results show that there are 23 kinds of organic compounds in the Chinese medicinal plant Ranunculus ternatus Thunb from Henan, among which 15 kinds of fatty acids were identified, including myristic acid, palmitic acid, stearic acid, oleic acid, linolenic acid, eicosanoic acid, docosanoic acid etc. The unsaturated fatty acids and oleic acid account for 58.19% and 35.68% of the total organic compounds respectively. The kinds of fatty acid in petroleum ether extract and ether extract are the same.

Alkanes↗

PubMed2006

[Relation of plasma brain natriuretic peptide to serum creatine kinase MB level in patients with acute myocardial infarction following primary percutaneous coronary intervention].

OBJECTIVE: To study the relation between plasma brain natriuretic peptide (BNP) and serum creatine kinase MB (CK-MB) level in patients with acute myocardial infarction (AMI) following primary percutaneous coronary intervention (PCI). METHODS: Sixty-three consecutive patients with AMI were divided into two groups according to the timing of PCI, namely direct PCI and indirect PCI groups. Plasma BNP levels were measured in all patients on admission and at 4, 24 and 48 h after admission. The CK-MB level was measured every 3 h on the first day of hospitalization, every 6 h on the second day and every 12 h on the third day. RESULTS: BNP level increased gradually following admission and began to decrease 48 h after admission in the two groups of patients. The peak BNP level occurred at 24 h after admission, and the BNP levels in patients of indirect PCI group were significantly higher than that of direct PCI group at 4, 24 and 48 h after admission. The peak CK-MB level of the direct PCI group occurred significantly earlier than that of the indirect group. CONCLUSION: Plasma BNP level may serve as an important objective indicator for recanalization of the infarct-related arteries following PCI in the early stage of AMI, which can help in the decision on clinical treatment plans for AMI.

Aged↗

PubMed2005

Effects of Brn-3a protein and RNA expression in rat brain following low-level lead exposure during development on spatial learning and memory.

The developing nervous system is preferentially vulnerable to lead exposure with alterations in neuronal and glial cells of the brain. Chronic exposure to lead (Pb2+) causes deficits of learning and memory in children and spatial learning deficits in developing rats. Brn-3a is a member of the Pit-Oct-Unc (POU) family of transcription factors that is expressed predominantly in neuronal cells. It exists in two forms, with the long form containing 84 amino acids at the N-terminus that are lacking in the short form. The N-terminal domain unique to the long form induces expression of the Bcl-2 gene and protects neuronal cells against apoptosis whereas the C-terminal POU domain common to both forms is sufficient for activating a number of other neuronally expressed genes and stimulating neuronal process outgrowth. We examined Brn-3a protein and RNA expression in rat brain following low-level lead exposure during development and subsequent effects on spatial learning and memory. Two groups of rats were investigated: a control group and a lead-exposed group (0.2% lead acetate in the drinking water of the dam from gestational day 15 to postnatal day 21). Levels of Brn-3a were measured in rat cortex, hippocampus and cerebellum by immunohistochemistry and in situ hybridization, both protein and mRNA levels were reduced in lead-exposed group (p < 0.05). In Morris water maze, we found spatial learning deficits in rats of lead-exposed group (p < 0.05). These data suggest that the alteration of Brn-3a may play a key role in the mechanisms underlying lead neurotoxicity.

Animals↗

PubMed2005

Complex nonlinear deformation of nanometer intergranular glassy films in beta-Si3N4.

The mechanical properties of a model of Y-doped intergranular glassy film in silicon nitride ceramics are studied by large-scale ab initio modeling. By linking directly to its electronic structure, it is shown that this microstructure has a complex nonlinear deformation under stress and Y doping significantly enhances the mechanical properties. The calculation of the electrostatic potential across the film supports the space charge model in ceramic microstructures.

Journal Article↗

PubMed2005

Erythropoietin protects against 6-hydroxydopamine-induced dopaminergic cell death.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the death of midbrain dopaminergic neurons. In the present study, erythropoietin, a trophic factor that has both hematopoietic and neural protective characteristics, was investigated for its capacity to protect dopaminergic neurons in experimental Parkinson's disease. Using both the dopaminergic cell line, MN9D, and primary dopamine neurons, we show that erythropoietin (1-3 U/mL) is neuroprotective against the dopaminergic neurotoxin, 6-hydroxydopamine. Protection was mediated by the erythropoietin receptor, as neutralizing anti-erythropoietin receptor antibody abrogated the protection. Activation of Akt/protein kinase B (PKB), via the phosphoinositide 3-kinase pathway, is a critical mechanism in erythropoietin-induced protection, while activation of extracellular signal-regulated kinase (ERK)1/2 contributes only moderately. Indeed, transfection of constitutively active Akt/PKB into dopaminergic cells was sufficient to protect against cell death. Furthermore, erythropoietin diminished markers of apoptosis in MN9D cells, including caspase 9 and caspase 3 activation and internucleosomal DNA fragmentation, suggesting that erythropoietin interferes with the apoptosis-execution process. When erythropoietin was administered to mice unilaterally lesioned with 6-hydroxydopamine, it prevented the loss of nigral dopaminergic neurons and maintained striatal catecholamine levels for at least 8 weeks. Erythropoietin-treated mice also had significantly reduced behavioral asymmetries. These studies suggest that erythropoietin can be an effective neuroprotective agent for dopaminergic neurons, and may be useful in reversing behavioral deficits associated with Parkinson's disease.

Animals↗

PubMed2005

Block of hERG channel by ziprasidone: biophysical properties and molecular determinants.

Ziprasidone, an antipsychotic agent, delays cardiac repolarization and, thus, prolongs the QT interval of the cardiac ECG. In this study, we examined the biophysical properties and the molecular determinants of the ziprasidone block of wild-type hERG potassium channels stably expressed in HEK-293 cells or wild-type and mutant hERG channels expressed in Xenopus oocytes. In stably transfected HEK-293 cells, ziprasidone blocked wild-type hERG current in a voltage- and concentration-dependent manner (IC(50)=120nM, 0mV, 37 degrees C). Ziprasidone showed minimal tonic block of hERG current estimated during a depolarizing voltage (-20 or +30mV) or evaluated by the envelope of tails test (+30mV). Rate of the block onset was rapid, but not significantly affected by test potentials ranging from -20 to +30mV (time constant (tau)=114+/-14ms at +30mV). The time constant of the slow component of hERG current deactivation (at -50mV) was significantly increased by ziprasidone (tau=1776+/-90 versus 1008+/-71ms, P<0.01). Time course of channel inactivation was slowed by ziprasidone in a voltage-dependent manner. The V(1/2) values for steady-state activation and inactivation of hERG channel in HEK-293 cells were not significantly altered by ziprasidone. In Xenopus oocytes, ziprasidone exhibited less potent block of wild-type hERG current (IC(50)=2.8microM, 0mV, 23 degrees C). Mutation of the aromatic residues (Tyr-652 or Phe-656) located in the S6 domain of hERG dramatically reduced the potency of channel block by ziprasidone (IC(50)>0.4 and 1mM at 0mV for Y652A and F656A, respectively). In conclusion, ziprasidone preferentially binds to and blocks open hERG channels. Tyr-652 and Phe-656 are two critical residues in the ziprasidone-binding site.

Animals↗

PubMed2005

Loss of function of def selectively up-regulates Delta113p53 expression to arrest expansion growth of digestive organs in zebrafish.

Transcription factor p53 forms a network with associated factors to regulate the cell cycle and apoptosis in response to environmental stresses. However, there is currently no direct genetic evidence to show if or how the p53 pathway functions during organogenesis. Here we present evidence to show that the zebrafish def (digestive-organ expansion factor) gene encodes a novel pan-endoderm-specific factor. A loss-of-function mutation in def confers hypoplastic digestive organs and selectively up-regulates the expression of Delta113p53, counterpart to a newly identified isoform of p53 produced by an alternative internal promoter in intron 4 of the p53 gene in human. The increased Delta113p53 expression is limited to within the mutant digestive organs, and this increase selectively induces the expression of p53-responsive genes to trigger the arrest of the cell cycle but not apoptosis, resulting in compromised organ growth in the mutant. Our data demonstrate that, while induction of expression of p53 and/or its isoforms is crucial to suppress abnormal cell growth, Delta113p53 is tightly regulated by an organ/tissue-specific factor Def, especially during organogenesis, to prevent adverse inhibition of organ/tissue growth.

Animals↗

PubMed2005

[Clinical investigation on the effect of intravesical instillation of antifibrinolytic agents with bacillus Calmette-Guerin on preventing bladder cancer recurrence].

OBJECTIVE: To investigate the effect of intravesical instillation of antifibrinolytic agents with bacillus Calmette-Guerin (BCG) on preventing recurrence of superficial bladder transitional cell carcinoma (BTCC) after surgical management. METHODS: A total of 326 cases of superficial BTCC undergoing transurethral resection of bladder tumor (TURBT) or partial cystectomy were divided into 5 groups. Then the different dosage BCG with or without antifibrinolytic agents was regular instilled into bladders (once a week, then once a month after 6 times). Group A including 66 cases received intravesical instillation of 100-120 mg BCG plus 100 mg para-aminomethyl benzoic acid (PAMBA). Group B including 64 cases: instillation of 50-60 mg BCG plus 100 mg PAMBA; Group C including 65 cases: 100-120 mg BCG plus 2.0 g epsilon-aminocaproic acid (EACA); Group D including 64 cases: 50-60 mg BCG plus 2.0 g EACA; Group E (control group) including 67 cases: 100-120 mg BCG. All the cases had been followed up for 4 to 69 months (mean, 28.5 months). Not only was cystoscopy performed every 3 months, but also biopsy was carried out to identify recurrence when necessary. Side effect was recorded after instillation. RESULTS: The rate of tumor recurrence of Group A, Group B, Group C and Group D was 12%, 10%, 9%, 9% respectively, which was significantly lower than that of Group E (30%) (chi(2) = 5.699, 6.818, 7.380, 7.867, P = 0.017, 0.009, 0.007, 0.005). And there was no significant difference of tumor recurrence rate between Group A and Group B or between Group C and Group D (Group A and Group C: high dosage BCG plus antifibrinolytic agents, while Group B and Group D: low dosage BCG plus antifibrinolytic agents) (P > 0.05). But the side effects developing in Group B and Group D after BCG instillation were less than those in Group A and Group C. CONCLUSIONS: The efficacy of BCG on prevention the recurrence of superficial BTCC can be enhanced when combined with antifibrinolytic agents. Even if the dosage of BCG was reduced by half, the efficacy didn't changed. A new approach of low dosage BCG plus antifibrinolytic agents is recommended in the prophylaxis of recurrence of bladder cancer.

4-Aminobenzoic Acid↗

PubMed2005

Glucocorticoid regulation of genes in the amiloride-sensitive sodium transport pathway by semicircular canal duct epithelium of neonatal rat.

The lumen of the inner ear has an unusually low concentration of endolymphatic Na+, which is important for transduction processes. We have recently shown that glucocorticoid receptors (GR) stimulate absorption of Na+ by semicircular canal duct (SCCD) epithelia. In the present study, we sought to determine the presence of genes involved in the control of the amiloride-sensitive Na+ transport pathway in rat SCCD epithelia and whether their level of expression was regulated by glucocorticoids using quantitative real-time RT-PCR. Transcripts were present for alpha-, beta-, and gamma-subunits of the epithelial sodium channel (ENaC); the alpha1-, alpha3-, beta1-, and beta3-isoforms of Na+-K+-ATPase; inwardly rectifying potassium channels [IC50 of short circuit current (Isc) for Ba2+: 210 microM] Kir2.1, Kir2.2, Kir2.3, Kir2.4, Kir3.1, Kir3.3, Kir4.1, Kir4.2, Kir5.1, and Kir7.1; sulfonyl urea receptor 1 (SUR1); GR; mineralocorticoid receptor (MR); 11beta-hydroxysteroid dehydrogenase (11beta-HSD) types 1 and 2; serum- and glucocorticoid-regulated kinase 1 (Sgk1); and neural precursor cell-expressed developmentally downregulated 4-2 (Nedd4-2). On the other hand, transcripts for the alpha4-subunit of Na+-K+-ATPase, Kir1.1, Kir3.2, Kir3.4, Kir6.1, Kir6.2, and SUR2 were found to be absent, and Isc was not inhibited by glibenclamide. Dexamethasone (100 nM for 24 h) not only upregulated the transcript expression of alpha-ENaC (approximately 4-fold), beta2-subunit (approximately 2-fold) and beta3-subunit (approximately 8-fold) of Na+-K+-ATPase, Kir2.1 (approximately 5-fold), Kir2.2 (approximately 9-fold), Kir2.4 (approximately 3-fold), Kir3.1 (approximately 3- fold), Kir3.3 (approximately 2-fold), Kir4.2 (approximately 3-fold), Kir7.1 (approximately 2-fold), Sgk1 (approximately 4-fold), and Nedd4-2 (approximately 2-fold) but also downregulated GR (approximately 3-fold) and 11beta-HSD1 (approximately 2-fold). Expression of GR and 11beta-HSD1 was higher than MR and 11beta-HSD2 in the absence of dexamethasone. Dexamethasone altered transcript expression levels (alpha-ENaC and Sgk1) by activation of GR but not MR. Proteins were present for the alpha-, beta-, and gamma-subunits of ENaC and Sgk1, and expression of alpha- and gamma-ENaC was upregulated by dexamethasone. These findings are consistent with the genomic stimulation by glucocorticoids of Na+ absorption by SCCD and provide an understanding of the therapeutic action of glucocorticoids in the treatment of Meniere's disease.

11-beta-Hydroxysteroid Dehydrogenases↗

PubMed2005

Immunohistochemical analysis of P57(kip2), p53 and hsp60 expressions in premalignant and malignant oral tissues.

To investigate the expressions and significances of P57(kip2), p53 and hsp60 proteins in the dysplasia-carcinoma sequence of oral mucosa. A retrospective study was performed in 10 cases of normal oral mucosa, 79 cases of leukoplakia and 67 cases of squamous cell carcinoma (SCC). The expressions of P57(kip2), p53 and hsp60 proteins were detected in the tissue samples of these populations using immunohistochemical method. P57(kip2) expression was decreased in oral leukoplakia with moderate or severe dysplasia, and further decreased in oral SCC. Negative expression of P57(kip2) was significantly associated with advanced tumor size, the occurrence of lymph node metastasis and the advanced clinical stage in oral SCC. The overall 5-year survival rate in the P57(kip2) positive group was significantly higher than that in the P57(kip2) negative group. P57(kip2) expression was decreased in oral leukoplakia with moderate or severe dysplasia, and further decreased in oral SCC. It was a remarkable progressive and prognostic biomarker in oral SCC.

Biomarkers, Tumor↗

PubMed2005

Contribution of p16INK4a and p21CIP1 pathways to induction of premature senescence of human endothelial cells: permissive role of p53.

We have previously found that nonenzymatically glycated collagen I (GC), mimicking diabetic microenvironment, can induce senescent phenotype in early passage human umbilical vein endothelial cells (HUVECs). In the present study, we explored the functional involvement of cell cycle checkpoint pathways in initiating GC-induced premature endothelial cell senescence. When compared with native collagen, early passage HUVECs showed increased p53, p21(CIP1) (p21), and p16(INK4a) (p16) mRNA expression after exposure to GC. Twenty-four hours after transfection of p16, p21, and p53-enhanced green fluorescent protein (EGFP) recombinant plasmids, HUVECs entered G(1)-phase cell cycle arrest. By days 3 and 5, HUVECs transfected with p16-EGFP showed an increased proportion of senescent cells, and this increase was more prominent in the GFP-positive cell population, which exhibited 68% of senescent cells. Transfection of p21 also induced senescence but only by day 5. Cotransfection of p16 and p21 showed no additive effect. Transfection of p21 or p53 induced apoptosis in HUVECs. Next, we suppressed endogenous p53, p21, p16, or retinoblastoma (Rb) gene expression through small interference RNA strategy and investigated their influence in p16- and p21-initiated endothelial cell senescence. Analysis indicated that suppression of p53 expression can abolish senescence induced by p16 overexpression. Paradoxically, this effect was not observed when p21 was suppressed. On the other hand, suppression of Rb eliminated senescence initiated by either p16 or p21 overexpression. In summary, the p53/p21 pathway is mainly responsible for GC-induced apoptosis, but the coordinated activation of the p53/p21 and p16 pathway is responsible for GC-induced endothelial cell senescence through a Rb-dependent mechanism.

Animals↗

PubMed2005

Expression, purification, and immobilization of His-tagged D-amino acid oxidase of Trigonopsis variabilis in Pichia pastoris.

High-level expression of D: -amino acid oxidase (DAO) has been reported in Pichia pastoris by integrating the DAO gene under the control of the alcohol oxidase promoter (PAOX1). However, the time taken to reach peak product concentration is usually long (approximately 43 h), and cultivation requires tight regulation of methanol feeding. In this paper, we describe the expression of His-tagged DAO (HDAO) in P. pastoris using the glyceraldehydes-3-phosphate dehydrogenase promoter (PGAP). The maximal level of HDAO expression using the PGAP integrant is attained in 13 h and is equal to that obtained using the PAOX1 integrant in 43 h. We also explored the possibility of secreting HDAO in P. pastoris. In-frame fusion of Saccharomyces cerevisiae alpha-factor secretion signal under a PGAP or PAOX1 resulted in low-level secretion of active HDAO, which was not of practical use. The intracellularly expressed HDAO under PGAP was purified by agar-based affinity support and then immobilized on Amberzyme oxirane resin. The immobilized HDAO, with specific activity of 75 U g-1 (wet weight), could be recycled more than 14 times without significant loss of activity. The data suggest that intracellular production of HDAO under PGAP, followed by affinity purification and immobilization on oxirane resin, may serve as an effective process for the manufacture of immobilized DAO for industrial application.

Bioreactors↗

PubMed2005

Quantification of lipoic acid in plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry.

A sensitive and specific liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) method has been developed and validated for the identification and quantification of lipoic acid (LA) in human plasma. LA and the internal standard, naproxen, were extracted from a 500 microl plasma sample by one-step deproteination using acetonitrile. Chromatographic separation was performed on a Zorbax SB-C(18) Column (100 mmx3.0mm i.d. with 3.5 microm particle size) with the mobile phase consisting of acetonitrile and 0.1% acetic acid (pH 4, adjusted with ammonia solution) (65:35, v/v), and the flow rate was set at 0.3 ml/min. Detection was performed on a single quadrupole mass spectrometer by selected ion monitoring (SIM) mode via electrospray ionization (ESI) source. The method was linear over the concentration range of 5-10,000 ng/ml for LA. The intra- and inter-day precisions were less than 7% and accuracy ranged from -7.87 to 9.74% at the LA concentrations tested. The present method provides a relatively simple and sensitive assay with short turn-around time. The method has been successfully applied to a clinical pharmacokinetic study of LA in 10 healthy subjects.

Administration, Oral↗