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Biomedical subjects

Peng Wang

Publications and source records attributed to Peng Wang.

At least 163 records · Page 9Linked to original sources
PubMed2004

[The new secondary metabolite from Polygonatum odoratum].

OBJECTIVE: To investigate the chemical constituents of Polygonatum odoratum. METHOD: Silica gel column chromatography was used to separate and purify the chemical constituents. The structures were elucidated by chemical and spectral analysis. RESULT: One dipeptide and one furostanol glycoside were isolated from the rhizomes of P. odoratum, and their structures were identified as O-acetate of N (N-benzoyl-S-phenylalaninyl)-S-phenylalaninol (1) and 22-hydroxy-25 (R and S)-furost-5-en-12-on-3beta,22,26-triol 26-O-beta-D-glucopyranoside (2), respectively. CONCLUSION: Compound (2) is a new compound and is first reported to be of the furostanol monoglycoside glycosylated at C-26.

Glucosides↗
PubMed2004

[Simultaneous determination of seven sexual hormones in cosmetics by reversed-phase high performance liquid chromatography].

An efficient method for analyzing seven sexual hormones in cosmetics, namely, estriol, estradiol-17beta, estrone, testosterone, methyl-testosterone, progesterone and diethylstilbestrol by reversed-phase high performance liquid chromatography was developed. Samples were saponified with 20 g/L sodium hydroxide. The sexual hormones were then extracted with dichloromethane-acetic acetate (40:1, v/v) under acidic conditions (pH 3, adjusted with 1 mol/L HCl). An XTerra RP18 column was employed and a mixture of water-methanol-acetonitrile (50:32:18, v/v) was used as mobile phase. The seven sexual hormones were detected at 230 nm. The average spiked recoveries for the seven sexual hormones ranged from 75.6% to 97.8% with relative standard deviations of 1.9% to 7.2%. The linear ranges of determination were from 5 to 50 mg/L with correlation coefficients of 0.9999, and the limits of detection were from 3.7 to 12 ng. The method is suitable to simultaneously assay the seven sexual hormones in cosmetics with simplicity and accuracy in a single injection.

Chromatography, High Pressure Liquid↗
PubMed2003

Isolation of extremophiles with the detection and retrieval of Shewanella strains in deep-sea sediments from the west Pacific.

Tests to detect the presence of piezophilic Shewanella strains in the deep-sea sediments of the west, mid- and east Pacific at different depths were done by amplification of previously identified pressure-regulated operons (ORF1,2 and ORF3). The operon fragments were detected in all the deep-sea sediment samples, indicating the broad presence of piezophilic deep-sea Shewanella species or related species in the deep-sea sediments across the Pacific. Extremophiles were isolated from the deep-sea sediment of the west Pacific under atmospheric pressure. Two psychrophilic/psychrotrophic strains, WP2 and WP3, were assigned to the Shewanella genus as determined by their 16S rDNA sequences. WP2 and WP3 were both capable of amplifying pressure-regulated operons; the sequences of the pressure-regulated operons of WP2 and WP3 share high identity between each other, but have more differences from those of S. benthica and S. violacea. The major fatty acids of WP2 and WP3 are 3OH-i-13:0, 14:0, i-15:0, 16:0, 16:1, 18:1, and 20:5. Combined phenotypic analysis, 16S rDNA sequences, and DNA-DNA hybridization results suggest that WP2 and WP3 are two new deep-sea Shewanella species.

Amino Acid Sequence↗
PubMed2003

Identification and characterization of a new human type 9 cGMP-specific phosphodiesterase splice variant (PDE9A5). Differential tissue distribution and subcellular localization of PDE9A variants.

Previously, four splice variants of human cGMP-specific phosphodiesterase (PDE) 9A (PDEs 9A1, 9A2, 9A3 and 9A4) have been identified. In this study, we have cloned a cDNA representing a new human PDE9A variant (PDE9A5). PDE9A5 encodes a protein of 492 amino acids, smaller than PDEs 9A1 and 9A2 but larger than PDEs 9A3 and 9A4. The exon structure of PDE9A5 is different from those of PDEs 9A1, 9A2, 9A3 and 9A4 in that, of the 20 exons of PDE9A gene, it lacks exons 2 and 5. PDE9A5 has been characterized in comparison with PDE9A1, the longest PDE9A variant. PDEs 9A5 and 9A1 have similar enzymatic properties. They both have a high affinity for cGMP with similar Km values (0.39 and 0.25 microM, respectively), although they have slightly different Vmax values (2.55 and 0.96 micromol/min/mg, respectively). They exhibit very similar divalent metal ion dependency and inhibitor sensitivity. Real-time quantitative PCR analysis shows that PDEs 9A5 and 9A1 exhibit differential tissue distribution. They are highly expressed in immune tissues (spleen, lymph node and thymus) and are more abundant in T cells than in B cells, neutrophils and monocytes. When transiently expressed in HEK293 cells, PDEs 9A5 and 9A1 proteins exhibit differential subcellular localization. PDE9A5 localizes exclusively in the cytoplasm, whereas PDE9A1 localizes in the nucleus only. The nuclear localization of PDE9A1 is dependent on a unique pat7 motif. By Western blot analysis, native PDE9A1 is detectable in the nucleus but not in the cytoplasm of T cells. Thus, to our knowledge, PDE9A1 is the only PDE isoform found to localize exclusively in the nucleus. We speculate that the physiological role of the PDE9A diversity may be imparting cGMP-metabolizing ability to specific cellular compartments in appropriate tissues.

1-Methyl-3-isobutylxanthine↗
PubMed2003

Dissociating the enhancing and inhibitory effects of pertussis toxin on autoimmune disease.

Pertussis toxin (PT) has both enhancing and inhibitory effects on experimental autoimmune disease, depending on its time of administration relative to immunization. The inhibitory effect is due to blocking of G(i)-coupled receptors by the enzymatic A subunit. In this study, we attribute the enhancing effect of PT to the cell-binding B subunit (PT-B). C57BL/6 mice, a strain that requires PT to develop experimental uveitis, were immunized with a retinal Ag and were injected with whole PT, PT-B, or vehicle. Disease and associated immunological responses were evaluated. The results showed that PT-B, determined to be free of biologically significant contamination with whole PT or with endotoxin, was able to mimic all the effects of PT with respect to disease induction, enhancement of delayed-type hypersensitivity, enhancement of lymphocyte proliferation, induction of an innate IL-12 response, and promotion of an adaptive IFN-gamma response to the uveitogenic Ag. Our results suggest that PT-B is largely responsible for the disease-enhancing properties of PT.

Adjuvants, Immunologic↗
PubMed2003

A stable quasi-solid-state dye-sensitized solar cell with an amphiphilic ruthenium sensitizer and polymer gel electrolyte.

Dye-sensitized nanocrystalline solar cells (DSC) have received considerable attention as a cost-effective alternative to conventional solar cells. One of the main factors that has hampered widespread practical use of DSC is the poor thermostability encountered so far with these devices. Here we show a DSC with unprecedented stable performance under both thermal stress and soaking with light, matching the durability criteria applied to silicon solar cells for outdoor applications. The cell uses the amphiphilic ruthenium sensitizer cis-RuLL'(SCN)(2) (L = 4,4'-dicarboxylic acid-2,2'-bipyridine, L' = 4,4'-dinonyl-2,2'-bipyridine) in conjunction with a quasi-solid-state polymer gel electrolyte, reaching an efficiency of >6% in full sunlight (air mass 1.5, 100 mW cm(-2)). A convenient and versatile new route is reported for the synthesis of the heteroleptic ruthenium complex, which plays a key role in achieving the high-temperature stability. Ultramicroelectrode voltammetric measurements show that the triiodide/iodide couple can perform charge transport freely in the polymer gel. The cell sustained heating for 1,000 h at 80 degrees C, maintaining 94% of its initial performance. The device also showed excellent stability under light soaking at 55 degrees C for 1,000 h in a solar simulator (100 mW cm(-2)) equipped with a ultraviolet filter. The present findings should foster widespread practical application of dye-sensitized solar cells.

Coloring Agents↗
PubMed2003

A novel pH- and time-dependent system for colonic drug delivery.

A novel pH- and time-dependent delivery system was developed for delivering drugs to the colon. In vitro studies showed that this novel system could release the drug at a predetermined time, which was mainly controlled by the coating layers of the system. The delayed time of the press-coating layer was controlled by its erosion rate, which followed Hixson-Crowell equation. A proper selection of such factors as the viscosity grade of HPMC and tablet hardness, etc., can help reproduce the drug release profile as expected. The transit profiles in two healthy volunteers by gamma scintigraphy demonstrated that the tablets were able to pass through the stomach and small intestine intact and could safely reach the distal end of the small intestine, where the system began to release the drug contained in the core tablet. For both of the volunteers, disintegration of the tablets occurred in the ascending colon, which had highlighted the potential of this system for colonic drug delivery.

Adult↗
PubMed2003

Using oxidation-reduction potential (ORP) and pH value for process control of shortcut nitrification-denitrification.

A new low cost technology for simultaneous carbon-nitrogen removal from soybean wastewater has been developed in this study. The technology is performed through shortcut nitrification-denitrification. The process operated under realtime control of aeration and mixing time. The shortcut nitrification-denitrification in sequencing batch reactor (SBR) was achieved efficiently and steadily by controlling temperature (28 +/- 0.5 degrees C) and using real-time control strategies. This enabled the prevention of nitrite oxidation, leading to lower operational costs. The feasibility of oxidation-reduction potential (ORP) and pH value as control parameter for shortcut nitrification-denitrification process was also investigated. Results showed that the average removal efficiency of ammonium was more than 95%, and nitrosation rate (NO2(-)-N/NOx(-)-N) was reached to 96%. At the same time, the variation of oxidation--reduction potential (ORP) and pH value was well related to organic matter degradation and ammonium oxidation in SBR. So that judgment on the ending of nitrification and denitrification can be based on the inflection point on the varied curve of ORP and pH throughout each SBR processing cycle, and thus reducing aeration and mixing time for saving energy source. The method saves organic energy up to 40% of chemical oxygen demand (COD) in denitrification process, which should reduce the need for an extra external source of organic carbon. Shorter hydraulic retention time should allow the volume of the reactors to diminish, and thus diminish investment costs. Lower oxygen demand of about 25% gives lower exploitation costs.

Agriculture↗
PubMed2003

A study on prediction of the bio-toxicity of substituted benzene based on artificial neural network.

Quantitative Structure-Activity Relationship (QSAR) between the bio-toxicity of seventy-eight kinds of substituted benzene chemicals to yeast Saccharomyces cerevisiae (1g(1/Cmiz)) and the components of vertex degree autocorrelation vectors (values of A, B, C and D) was studied by using the software of Artificial Neural Network (ANN). The key factors of the autocorrelation descriptors for the 1g (1/Cmiz) value of yeast Saccharomyces cerevisiae, A [0], A [1], C [3], C [5] and D [3] were selected from twenty-four descriptors, and were explained theoretically in this paper. The QSAR-ANN model has been used to predict the bio-toxicity of twenty-three substituted benzene chemicals. The correlation between Cmiz and LC50 was also discussed, and the liner correlation equation between them was established.

Benzene↗
PubMed2003

Characteristics and mechanisms of isolated rubella virus, strain JR23: infection of the central nervous system of BALB/c mice.

OBJECTIVE: To investigate the correlation between rubella virus (RuV) antigen in peripheral lymphocytes, the immune status and RuV infection in the central nervous system (CNS). METHODS: BALB/c mice were used as a model and treated with immunoaffecting medicines. Then, the mice were infected with RuV via the abdominal cavity, and the antigen level in peripheral lymphocytes was examined 1, 3, 7 and 14 days postinfection. RuV in the CNS was detected by immunohistochemical methods. BALB/c mice were given dexamethasone and cytoxan before infection with the RuV JR23 strain. Immune functions and RuV invasion of the CNS were assayed on day 21 postinfection via the abdominal cavity, and their relationship was analyzed. RESULTS: The mean antigen detection rates at different times were 3.1, 4.1, 9.6 and 2.4%, respectively, in the dexamethasone group, and 14.2, 12.7, 9.9 and 3.1%, respectively, in the cytoxan group. In the group without any intervention, the detection rates were 4.63, 10.25, 6.88 and 1.75%, respectively. The antigen detection rates in peripheral lymphocytes among the three groups 24 h postinfection were significantly different (F = 0.0317, p < 0.05). Comparisons between groups showed that antigen detection rates in the cytoxan group were much higher than those in other groups, but there was no difference between the dexamethasone and control groups. The animals with persistent presence of antigen were much more susceptible to cerebral infection than those with short-term presence (p < 0.001). T cell functions of the cytoxan group were significantly lower than those of other groups (p < 0.05), as detected by the MTT method. Infection rates of the dexamethasone, cytoxan and control groups were 60, 90 and 50%, respectively. Cell immune functions of the mice with CNS infection were obviously worse than those of the mice without CNS infection (p < 0.001). RuV-specific antibodies were assayed in all groups by ELISA and the results showed that there were no significant differences among groups (p < 0.05) or between the groups with and without CNS infection. CONCLUSION: Cytoxan can affect virus detection rates in peripheral lymphocytes. At the early phase of infection, the persistent presence of RuV in peripheral lymphocytes increases the incidence of CNS infection. RuV infection in the CNS was related to the cell immune situation before specific antibody was produced in the body.

Animals↗
PubMed2003

Methimazole protects from experimental autoimmune uveitis (EAU) by inhibiting antigen presenting cell function and reducing antigen priming.

Methimazole (methyl-mercapto-imidazole, MMI), a compound used clinically in therapy of Graves' thyroiditis, was found to inhibit development of several autoimmune diseases in animal models. It was suggested on the basis of in vitro data that inhibition is through down-regulation of interferon-gamma (IFN-gamma)-induced expression of major histocompatibility complex class I and class II molecules. Here, we investigate the effect of MMI on experimental autoimmune uveoretinitis (EAU) and study its mechanism(s). Treatment of EAU with MMI administered in drinking water inhibited induction of the disease and associated antigen (Ag)-specific proliferation and cytokine production by draining lymph node cells (LNCs). The treatment was protective only if administered during the first but not during the second week after immunization, suggesting an effect on the induction phase of EAU. It is interesting that MMI inhibited disease in IFN-gamma knockout mice, indicating that the in vivo protective effect is IFN-gamma-independent. Flow cytometric analysis of draining LNCs extracted 5 days after immunization showed that MMI partly to completely reversed the increase in Mac-1(+)/class I(+)/class II(+) cells induced by immunization and reduced the proportion of B7-1 and CD40-positive cells, suggesting a deficit in the Ag-presenting cell (APC) population. APC from untreated mice largely restored antigen-specific proliferation of MMI-treated LNCs. We suggest that MMI inhibits EAU at least in part by preventing the recruitment and/or maturation of APC, resulting in reduced generation of Ag-specific T cells.

Animals↗
PubMed2003

The site-directed mutagenesis of gastrodia anti-fungal protein mannose-binding sites and its expression in Escherichia coli.

Gastrodia anti-fungal protein (GAFP) displays strong inhibitory activity against certain fungal pathogens. Five GAFP analogues with different mutations at mannose-binding sites and the wild-type one were expressed and purified in Escherichia coli. The inhibitory analysis of the purified various GAFPs against the growth of Trichoderma viride indicates that single amino acid mutated-type GAFPs have inhibitory activity, but its activity is much less than the wild-type one. The double and triplicate amino acids mutated GAFPs have very low inhibitory activity. For the first time it was proved that GAFP mannose-binding sites play key role in anti-fungi process.

Antifungal Agents↗
PubMed2003

Association of cyclooxygenase-2 expression with Hp-cagA infection in gastric cancer.

AIM: To observe the expression of cyclooxygenase-2 (COX-2) and to investigate the association between COX-2 expression and infection with cytotoxic-associated gene A (cagA) positive strain Helicobacter pylori (Hp) in human gastric cancer, and subsequently to provide fresh ideas for the early prevention of gastric cancer. METHODS: 32 Specimens of gastric cancer and corresponding adjacent normal gastric mucosa were obtained from patients who had undergone surgical operations of gastric cancer. All the samples including 1 case of stomach malignant lymphoma and 31 cases of gastric adenocarcinoma were confirmed by pathology diagnosis. The expression of COX-2 in 32 specimens of gastric cancer and corresponding adjacent normal gastric mucosa was quantitatively determined and analyzed with Flow Cytometry, and the levels of COX-2 protein were compared between specimens with cagA(+) Hp infection and those without cagA(+) Hp infection. The cagA gene in 32 specimens of gastric cancer was detected by polymerase chain reaction (PCR) method. RESULTS: Twenty-seven of 32 (84 %) specimens of gastric cancer showed over-expression of COX-2, compared with the adjacent normal gastric mucosa. cagA(+) gene were detected from 19 specimens of gastric cancer, but not from the other 13 specimens. The levels of COX-2 protein in 19 specimens of gastric cancer with cagA(+) Hp infection (the number of positive cells was 73.82+/-18.2) were significantly higher than those in the 13 specimens without cagA(+) Hp infection (the number of positive cells was 35.92+/-22.1). CONCLUSION: COX-2 is overexpressed in gastric cancer and cagA(+) Hp infection could up-regulate the expression of COX-2 in gastric cancer in human. There may also exist another way or channel to regulate the expression of COX-2 in gastric cancer in addition to cagA(+) Hp infection. Therefore, applying COX-2 selective inhibitors could be an effective and promising way to prevent gastric cancer.

Aged↗
PubMed2003

Value of echocardiography for observing left ventricular hypertrophy in the diagnosis of myocardial microvascular damage in hypertensives.

OBJECTIVE: To investigate the value of the echocardiographic observation of the left ventricular hypertrophy (LVH) in diagnosing myocardial microvascular damage in patients with essential hypertension (EH). METHODS: After intravenous injection with Quanfuxian (a contrast agent consisting of albumin and C3F8 prepared by Nanfang Hospital), the values of A (the maximum number of microbubbles accumulating in the local tissues for assessing the density of local microvessels), beta (the filling velocity of contrast agent for evaluating local blood flow velocity) and A x beta (the product of A and beta for estimating local myocardial blood flow) at rest and after dipyridamole injection were measured by intermittent harmonic imaging with myocardial contrast echocardiography (MCE). The ratios of A and beta along with the microvascular coronary flow velocity reserve (CFVR) were also calculated. RESULTS: Compared with the control group, the rest values of A, beta and A.beta in EH patients were higher, especially in those with LVH. After dipyridamole injection, the values of A, beta, A x beta and the ratios of A and beta, along with CFVR as well, were significantly lowered (P <0.01), and the reductions were especially obvious in LVH cases. As the hypertension exacerbated, the values of A and A x beta tended to increase in positive correlation with systolic and diastolic blood pressure (P <0.01), while the ratio of A and CFVR were decreased, the latter was inversely correlated with diastolic blood pressure (r=-0.55, P <0.01). Positive correlations were noted of the values of A and A x beta with the left ventricular mass and left ventricular mass index (P <0.01). CONCLUSION: EH patients, especially those with LVH, are characterized by increased rest myocardial microvascular blood flow, impaired myocardial microvascular flow reserve and endothelium independent vasodilation relaxing ability, and reduced capillary density, and these conditions tend exacerbate as the disease worsens. Microvascular function impairment should be suspected when complication of LVH arises in the EH patients. As a new important noninvasive technique, MCE can be a promising modality for diagnosing microvascular disease in essential hypertension.

Aged↗
PubMed2003

[Co-expression of CFA/I and CS6 of Enterotoxigenic Escherichia coli ( ETEC ) in Shigella flexneri 2a T32 Derivative Strain FWL01].

Among the known colonization factors of enterotoxigenic Escherichia coli (ETEC), CFA/I and CS6 (the common antigen in the CFA/IV fimbrial antigens ) are two of the most prevalent fimbriae found in clinical isolates but are never expressed by the same wild-type strains. In this study, CFA/I and CS6 of ETEC were co-expressed in Shigella flexneri 2a T32 derivative strain FWL01 by using a host-plasmid lethal balancing system based on asd gene. The results indicate that the recombinant plasmid carrying CFA/I and CS6 could be stably integrated in FWL01. Expression of the two antigens did not interfere the host growth. The results of immunofluorescence analysis showed that CFA/I and CS6 were localized on the surface of the strain FWL01. In Balb/c mice orally immunized with the recombinant strain, the immune responses against CFA/I and CS6 were observed. Those observations show the feasibility of a multivalent vaccine expressing different fimbrial antigens in attenuated Shigella flexneri.

Animals↗
PubMed2003

[Genetic analysis of Yersinia pestis strains isolated in China].

OBJECTIVE: The strains of Yersinia pestis isolated in different period and different natural foci in China were analyzed. METHODS: Traditional and molecular biological methods were used. Rhamnose fermentation, rRNA gene copy number, nitrite reduction, and the glycerol fermentation were important characters for typing, and pulse field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) profile could reflect the genetic distance between the strains. RESULTS: The strains could be divided into 15 genetic types by those 6 characters with each of them covered an isolated geographical territories. CONCLUSION: The characters of strains were described; the genetic relationship of different types, their evolution, and the forming and shift of plague natural foci were analyzed.

China↗