Biomedical subjects

Jun Chen

Publications and source records attributed to Jun Chen.

At least 271 records · Page 15Linked to original sources

PubMed2004

[Study on the SFE condition for curcumin in Curcuma longa].

OBJECTIVE: To optimize the conditions of supercritical fluid extraction (SFE) for curcumin in Curcuma longa. METHOD: Optimum extraction conditions were studied by orthogonal tests. The extracts were analyzed by HPLC. RESULT: The optimal extraction conditions were pressure 25 MPa, temperature 55 degrees C, static time 4 h, dynamic time 5 h, flow rate of CO2 3.5 L x min(-1), co-solvent ethanol 30% (mL x g(-1)). CONCLUSION: It is feasible to extract curcumin by SFE.

Carbon Dioxide↗

PubMed2004

[Expression of OsBP-73 gene requires involvement of its intron in rice].

It has been demonstrated in our previous work that rice OsBP-73 gene contains two exons interrupted by a 2471 bp intron. Here it was reported that the 5' flanking region of the ATG translation start codon in the first exon of OsBP-73 gene (from -1818 to +215) can not direct GUS gene expression in resistant rice calli or transgenic rice. When the complete OsBP-73 intron and its flanking region (from -1818 to +2844) are constructed in frame with GUS coding region, GUS activity can be detected in the resistant rice calli and transgenic rice. Experimental data also show that the complete OsBP-73 intron itself has no promoter activity. These results suggest that the OsBP-73 intron sequence is involved in directing the GUS gene expression. Another experiment demonstrates that the complete intron sequence can enhance the activity of OsEBP-89 gene promoter.

Gene Expression Regulation, Plant↗

PubMed2004

[Distribution of hydroxycamptothecin after aerosol inhalation in rabbits].

AIM: To investigate the tissue distribution and pharmacokinetics of hydroxycamptothecin (HCPT) after aerosol inhalation in rabbits. METHODS: RP-HPLC was used to determine the concentration of HCPT in different tissues and plasma of rabbits. The tissue distribution of HCPT after aerosol inhalation or iv administration was compared. The plasma concentrations at different time after aerosol inhalation were compared with iv injection. RESULTS: The HCPT concentrations in lung after aerosol inhalation at 0.5, 1 and 2 h were 13.52, 27.81 and 20.82 times higher than that of iv administration group, respectively. At the same time, concentrations in other tissues were decreased obviously. The absolute bioavailability of HCPT after aerosol inhalation was 7.38%. CONCLUSION: After aerosol inhalation, HCPT is retained mostly in lung. So this administration route can raise the therapeutic index and reduce adverse effects.

Administration, Inhalation↗

PubMed2004

[Optimization of piggery wastewater treatment with combined anaerobic hydrolysis and SBR process].

Anaerobic sequence batch reactor and aerobic sequence batch reactor were combined to treat the piggery wastewater. The ASBR was used to digest the wastewater for primary organic matter removal. Infections of digestion time to the wastewater's BOD/COD and to the nitrogen removal in behind SBR were studied. The result indicated that the wastewater with 36 hours' digestion retained high BOD/COD ratio of about 0.4. The nitrogen removal efficiency of this kind of wastewater in behind SBR was high with the effluent NH4+-N concentration less than 10 mg/L and a removal ratio higher than 99%. The total BOD5 removal ratio of A/O SBR was higher than 98% but the effluent COD(Cr) concentration couldn't meet the discharging standard before coagulating sedimentation.

Aerobiosis↗

PubMed2004

[Study on anti-bacterium activity of ginkgolic acids and their momomers].

OBJECTIVE: Ginkgolic acids and their three monomers were separated from ginkgo sarcotestas. The anti-bacterium activity of ginkgolic acids were tested. The relation between the anti-bacterium activity and side chain of ginkgolic acid were studied. METHOD: The MIC of ginkgolic acids and their three monomers and salicylic acid were tested. RESULTS: Ginkgolic acid has strong inhibitive effect on G+-bacterium. Salicylic acid has no side chain, so no anti-bacterial activity. When the length of gingkolic acid side chain is C13:0, it has the strongest anti-bacterial activity in three monomers. CONCLUSION: The side chain of ginkgolic acid is the key functional group that possessed anti-bacterial activity. The length of Ginkgolic acid was the main effective factor of anti-bacterial activity.

Anti-Bacterial Agents↗

PubMed2004

[Progress in research on constituents and pharmacological activities of sarcotestas of Ginkgo biloba].

The latest progress in research on constituents and pharmacological activities of sarcotestas of Ginkgo biloba has been studied. The main constituents in sarcotestas of G. biloba include flavones, ginkgolides, alkylphenols, polysaccharides and amino acids, etc. They show the following activities, such as bacteriostatic, bactericidal and pesticidal activities, antitumor and mutagenic, carcinogenic effects, antianaphylaxis and allergenic activity, effects on immunologic function, scavenging free radical, antisenile action, etc. The problems at present and the reseach direction for the future on sarcotestas of G. biloba have been put forward.

Animals↗

PubMed2004

[Comparison of effect between multiplex and simplex nutritional intervention on hyperlipemia, hypertension or diabetes].

OBJECTIVE: To explore the effect of simplex and multiplex nutritional intervention on hyperlipemia, hypertension or diabetes. METHODS: 260 persons who have hyperlipemia were randomized to 3 groups: (1) "the multiplex nutritional intervention group", is given 100 g coarse food grain everyday and nutrition education, (2) "the simplex nutritional intervention group", is only given nutrition education, (3) "the control group". RESULTS: After three months, the degressive value of blood pressure, blood sugar and blood lipid respectively in the multiplex nutritional intervention group were larger than in the simplex nutritional intervention. CONCLUSION: There are better effect on hyperlipemia, hypertension and diabetes by nutrition education plus passive dietary intervention than by nutrition education.

Aged↗

PubMed2004

[The process study on the extraction of irone by supercritical fuilds extraction].

OBJECTIVE: To study the condition for the extraction of irone in Iris tectorum by supercritical fluids extraction. METHOD: Conditions for the extraction were studied by a systematic method as guided by the content of irone presented in the extract. RESULTS: The best SFE conditions were: 0.411 mm raw material powder of Iris tectorum, 3% CHCl3 as modifier, temperature of extraction 50 degrees C under the pressure of 25 MPa, with CO2 flow rate of 120L/h, the static extracting time 2 h.

Carbon Dioxide↗

PubMed2003

Antisense BAG-1 sensitizes HeLa cells to apoptosis by multiple pathways.

To study the mechanism of action of BAG-1 in drug-induced apoptosis, we constructed an antisense BAG-1 vector and established a stably transfected cell line from BAG-1-over-expressing HeLa cells. Reduced BAG-1 protein was confirmed by Western blot. Treatment of the antisense BAG-1-transfected cells with the anti-cancer drugs staurosporine, paclitaxel, all-trans retinoic acid (ATRA), and N-(4-hydroxyphenyl) retinamide (4-HPR) resulted in significantly enhanced apoptosis and reduced cell viability relative to vector-transfected cells. While the expression of p53 was increased, the level of Bcl-2 and Bax was decreased. Cells underexpressing BAG-1 had reduced cytosolic cytochrome c level. Treatment with staurosporine and paclitaxel resulted in increased cytochrome c release from mitochondria, whereas there was no change induced by treatment with ATRA and 4-HPR. Our experiments suggest that BAG-1 inhibits anti-cancer drug-induced apoptosis through apoptosis regulation pathways that may involve the mitochondrial Bcl-2/Bax ratio, p53, and differential anti-cancer drug-mediated cytochrome c release.

Antineoplastic Agents↗

PubMed2003

Prevention and reversal of premature endothelial cell senescence and vasculopathy in obesity-induced diabetes by ebselen.

Although the accelerated atherosclerosis and premature aging of the cardiovascular system in patients with metabolic syndrome have been appreciated, the mechanisms of their development and potential therapeutic interventions remain unresolved. Our previous studies implicated advanced glycosylation end products in development of premature senescence preventable with a peroxynitrite scavenger, ebselen. Therefore, the effect of ebselen on endothelial senescence and vasculopathy in a model of metabolic syndrome--Zucker diabetic rats (ZDF)--was investigated. Ebselen decreased the abundance of 3-nitrotyrosine-modified proteins in ZDF rats. A 6-fold increase in the number of senescent endothelial cells in 22-week-old ZDF was prevented by ebselen. Development of vasculopathy, as collectively judged by the acetylcholine-induced vasorelaxation, NO production, angiogenic competence, and number of circulating microparticles, was almost completely prevented when ebselen was administered from 8 to 22 weeks and partially reversed when the treatment interval was 13 to 22 weeks. In conclusion, premature senescence of endothelial cells is progressively rampant in ZDF rats and is associated with the signs of severe vasculopathy. In addition, prevention of premature senescence of vascular endothelium through controlled decrease in nitrotyrosine formation was chronologically associated with the amelioration of vasculopathy, lending support to the idea of the pathogenetic role of premature senescence of endothelial cells in diabetic macrovasculopathy.

Acetylcholine↗

PubMed2003

Porosity of porcine bladder acellular matrix: impact of ACM thickness.

The objectives of this study are to examine the porosity of bladder acellular matrix (ACM) using deionized (DI) water as the model fluid and dextran as the indicator macromolecule, and to correlate the porosity to the ACM thickness. Porcine urinary bladders from pigs weighing 20-50 kg were sequentially extracted in detergent containing solutions, and to modify the ACM thickness, stretched bladders were acellularized in the same manner. Luminal and abluminal ACM specimens were subjected to fixed static DI water pressure (10 cm); and water passing through the specimens was collected at specific time interval. While for the macromolecule porosity testing, the diffusion rate and direction of 10,000 MW fluoroescein-labeled dextrans across the ACM specimens mounted in Ussing's chambers were measured. Both experiments were repeated on the thin stretched ACM. In both ACM types, the fluid porosity in both directions did not decrease with increased test duration (3 h); in addition, the abluminal surface was more porous to fluid than the luminal surface. On the other hand, when comparing thin to thick ACM, the porosity in either direction was higher in the thick ACM. Macromolecule porosity, as measured by absorbance, was higher for the abluminal thick ACM than the luminal side, but this characteristic was reversed in the thin ACM. Comparing thin to thick ACM, the luminal side in the thin ACM was more porous to dextran than in the thick ACM, but this characteristic was reversed for the abluminal side. The porcine bladder ACM possesses directional porosity and acellularizing stretched urinary bladders may increase structural density and alter fluid and macromolecule porosity.

Animals↗

PubMed2003

Effects of intravenous Injections Paederiae and Stauntonia on spontaneous pain, hyperalgesia and inflammation induced by cutaneous chemical tissue injury in the rat.

To study whether commercial traditional Chinese medicinal preparations Injection Paederiae (IP) or Injection Stauntonia (IS) has anti-nociceptive and/or anti-inflammatory effects, we used two persistent pain models (bee venom and formalin test) to evaluate the systemic effects of IP or IS on the chemical tissue injury-induced persistent spontaneous pain-related responses (PSPR), primary thermal/mechanical hyperalgesia and inflammation in conscious rats. Injection of bee venom (BV, 0.1 mg, 50 microl) into the plantar surface of one hind paw resulted in not only a 1-h monophasic PSPR such as flinching reflex in the injected paw and a subsequent period of 3-4 days primary heat and mechanical hyperalgesia, but also a marked sign of inflammation, including redness and swelling of the plantar surface in the injected paw. Intraplantar injection of formalin produced two phases of PSPR as reported previously. Systemic pre-treatment with three doses of IP (0.32, 1.6 and 9.0 ml/kg, 500%) or IS (0.32, 1.6 and 9.0 ml/kg, 250%) produced a dose-dependent suppression of the BV- or formalin-induced flinching reflex of 1 h time course as compared with the saline control group. Post-treatment with IP or IS 5 min after BV injection also produced a significant suppression of the flinching reflex in both BV test and formalin test respectively, as compared with the control group. However, neither pre- nor post-treatment with IP or IS produced any significantly suppressive effect on the BV-induced primary heat and mechanical hyperalgesia and inflammation. The analgesia produced by IP or IS was not mediated by the endogenous opioid receptors since naloxone, a non-selective opioid receptor antagonist, had no reversal effect on the IP and IS-produced analgesia in the BV-induced PSPR. Our present results suggest that IP or IS might prevent and relieve clinical persistent spontaneous pain, but without any anti-nociceptive and anti-inflammatory effects on the primary heat hyperalgesia, mechanical hyperalgesia, as well as inflammatory responses. The BV test might be a useful model of pain to evaluate and screen anti-nociceptive and anti-inflammatory effects of certain compounds of the Chinese medicinal herbs on the pathological origins of pain.

Analgesics↗

PubMed2003

T Cell Integrin Overexpression as a Model of Murine Autoimmunity.

Integrin adhesion molecules have important adhesion and signaling functions. They also play a central role in the pathogenesis of many autoimmune diseases. Over the past few years we have described a T cell adoptive transfer model to investigate the role of T cell integrin adhesion molecules in the development of autoimmunity. This report summarizes the methods we used in establishing this murine model. By treating murine CD4+ T cells with DNA hypomethylating agents and by transfection we were able to test the in vitro effects of integrin overexpression on T cell autoreactive proliferation, cytotoxicity, adhesion and trafficking. Furthermore, we showed that the ability to induce in vivo autoimmunity may be unique to the integrin lymphocyte function associated antigen-1 (LFA-1).

Journal Article↗

PubMed2003

Pharmacological activation of normal and arrhythmia-associated mutant KCNQ1 potassium channels.

KCNQ1 alpha-subunits coassemble with KCNE1 beta-subunits to form channels that conduct the slow delayed rectifier K+ current (IKs) important for repolarization of the cardiac action potential. Mutations in KCNQ1 reduce IKs and cause long-QT syndrome, a disorder of ventricular repolarization that predisposes affected individuals to arrhythmia and sudden death. Current therapy for long-QT syndrome is inadequate. R-L3 is a benzodiazepine that activates IKs and has the potential to provide gene-specific therapy. In the present study, we characterize the molecular determinants of R-L3 interaction with KCNQ1 channels, use computer modeling to propose a mechanism for drug-induced changes in channel gating, and determine its effect on several long-QT syndrome-associated mutant KCNQ1 channels heterologously expressed in Xenopus oocytes. Scanning mutagenesis combined with voltage-clamp analysis indicated that R-L3 interacts with specific residues located in the 5th and 6th transmembrane domains of KCNQ1 subunits. Most KCNQ1 mutant channels responded to R-L3 similarly to wild-type channels, but one mutant channel (G306R) was insensitive to R-L3 possibly because it disrupted a key component of the drug-binding site.

Amino Acid Substitution↗

PubMed2003

Molecular cloning and functional analysis of a novel type of Bowman-Birk inhibitor gene family in rice.

Bowman-Birk inhibitor (BBI) genes encode serine protease inhibitors that have repetitive cysteine-rich domains with reactive sites for the trypsin or chymotrypsin family. We have identified seven BBI genes from japonica rice (Oryza sativa subsp. japonica var Teqing). All of the genes identified were found in a single cluster on the southern end of the long arm of rice chromosome 1. Four of the seven BBI genes have two repetitive cysteine-rich domains, whereas one has a truncated domain with only one reactive site. We have also identified three novel BBI genes, each of which possesses three repetitive domains instead of two. In situ hybridization analyses indicated that the accumulation of rice BBI transcripts was differentially regulated in germinating embryos and also in the leaves, roots, and flower organs at later developmental stages. Different members of the rice BBI gene family displayed different expression patterns during rice seed germination, and wounding induced the expression of rice BBI transcripts. The three-domain BBIs had higher expression levels than the two-domain BBIs. It was also found that the mRNA of rice BBI genes was present in abundant amounts in scutellar epithelium and aleurone layer cells. RBBI3-1, one of the three-domain RBBI, exhibited in vitro trypsin-inhibiting activity but no chymotrypsin-inhibiting activity. Overexpression of RBBI2-3 in transgenic rice plants resulted in resistance to the fungal pathogen Pyricularia oryzae, indicating that proteinase inhibitors confer resistance against the fungal pathogen in vivo and that they might play a role in the defense system of the rice plant.

Amino Acid Sequence↗

PubMed2003

Contributions of lung tissue extracts to invasion and migration of human hepatocellular carcinoma cells with various metastatic potentials.

PURPOSE: The MHCC97 cell line contains two clones with high (MHCC97-H) and low (MHCC97-L) metastatic potentials, for which the pulmonary metastatic rate was 100% vs 40% between the two human hepatocellular carcinoma (HCC) clones. In an effort to elucidate the mechanism of organ-specific metastasis, we studied the effect of lung extracts from C57BL/6 mice on migration and invasion using the MHCC97 cell line. METHODS: Determination of migration and invasion induced by lung extracts to MHCC97 cell lines was examined by chemoinvasion assay. The organization of cytoskeleton was tested using filamentous actin (F-actin) polymerization assay and flow cytometry. The activity of matrix metalloproteinase (MMPs) was analyzed by zymogram. Fluorescence double staining was employed for MMPs and F-actin colocalization in MHCC97-H cells induced by lung extracts. RESULTS: The number of cells in response to extracts of lung, liver, kidney, and spleen in MHCC97-H cells was 64+/-10, 6+/-2, 22+/-4, and 3+/-1, respectively. Of the extracts, lung extracts showed significant differences to promote the migratory and invasive ability for MHCC97-H cells( p<0.001). The number of cells in response to lung extracts was threefold higher in MHCC97-H than that of cells in MHCC97-L ( p<0.001). Confocal laser scan microscope of MHCC97-H cells and MHCC97-L cells stimulated with lung extracts revealed pseudopodia formation around the cell front at the indicated time point. With the time increasing, the pseudopodia formation became increasingly more obvious and distinct. Compared with unstimulated cells, analysis of FACS showed a transient 1.9-fold and 1.7-fold increase in F-actin within 30 s in MHCC97-H cells and MHCC97-L cells, respectively. Confocal laser scan microscopy of MHCC97-H cells stimulated in suspension with lung extracts revealed intense F-actin staining in the periphery of the cells and redistribution of F-actin towards a leading edge. After the cells were incubated with lung extracts, not only expressions of active and latent form of MMP-9 were upregulated, but that of latent form of MMP-2 was increased in the MHCC97-H cells and MHCC97-L cells. The levels of latent and active form of MMP-9(18.8+/-1.2, 100.1+/-1.1), and latent form of MMP-2(22.4+/-1.3) were much higher in MHCC97-H cells than those of MHCC97-L cells, which were 7.8+/-0.3, 40.8+/-2.2, and 8.2+/-0.4, respectively. MMP-9 was mainly localized perinuclear pool when the MHCC97-H cells were incubated with serum-free medium. After the cells were stimulated with lung extracts, MMP-9 were expressed and colocalized with F-actin at the front of extending pseudopodia. CONCLUSIONS: Our results indicate that the expression of matrix metalloproteinase and the pseudopodia formation in MHCC97-H cells may correlate to the metastatic potential; thus, the host environment may contribute to the preferential metastasis of HCC cells to the lung depending on the high level of MMP-9 and migratory ability.

Animals↗

PubMed2003

Role of central NMDA versus non-NMDA receptor in spinal withdrawal reflex in spinal anesthetized rats under normal and hyperexcitable conditions.

The present study aimed to investigate the role of central N-methyl-D-aspartate (NMDA) and non-NMDA receptors in the spinal withdrawal reflex assessed by recording single motor unit (SMU) electromyogram (EMG) response to peripheral mechanical (pressure, pinch) stimuli and repeated electrical stimuli at 3 and 20 Hz. During normal conditions, intrathecal administration of MK-801 and CNQX apparently depressed mechanically and electrically (3 Hz) evoked EMG responses in a dose-dependent manner (10, 20 and 40 nmol in 10 microl). In contrast, the after-discharges to 20 Hz electrical stimuli were suppressed only by CNQX treatment, not by MK-801 treatment. This indicates that the central mechanisms underlying the different frequencies of electrically evoked withdrawal reflex may be different. During peripheral bee venom (BV, 0.2 mg/50 microl) induced inflammation and central sensitization, the enhanced SMU EMG responses including after-discharges to pinch stimuli and 3 Hz electrical stimuli were depressed significantly by treatments with both MK-801 and CNQX. However, the enhanced SMU activities to innocuous pressure stimuli were depressed only by treatment with CNQX. Likewise, enhanced long lasting after-discharges elicited by 20 Hz electrical stimuli were also only depressed by CNQX, indicating that different central mechanisms are involved in the persistent hyperexcitability during BV-induced inflammation. The data suggest that both central NMDA and non-NMDA receptors play important roles in the transmission of nociceptive information under normal conditions. In BV-induced inflammation, however, central non-NMDA receptors, but not NMDA receptors, play a pivotal role in the generation of persistent hyperexcitability to mechanical and electrical stimuli at different frequencies (3 Hz, 20 Hz).

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed2003

Electrochemical preparation of chitosan/hydroxyapatite composite coatings on titanium substrates.

Composite coatings containing brushite (CaHPO(4). 2H(2)O) and chitosan were prepared by electrochemical deposition. The brushite/chitosan composites were converted to hydroxyapatite/chitosan composites in aqueous solutions of sodium hydroxide. The coatings ranged from approximately 1 to 15% chitosan by weight. Qualitative assessment of the coatings showed adhesion significantly improved over that observed for electrodeposited coatings of pure HA.

Calcium Phosphates↗