Biomedical subjects

Peng Wang

Publications and source records attributed to Peng Wang.

At least 73 records · Page 4Linked to original sources

PubMed2006

[Separation and purification of skeletal muscle satellite cells for tissue engineering applications by Percoll].

OBJECTIVE: To investigate separation and purification of skeletal muscle satellite cells with improved incontinuous density Percoll gradient centrifugation technique. METHODS: The primary skeletal muscle satellite cells of New Zealand white rabbits were cultured with different adhesion time method and incontinuous density Percoll gradient centrifugation technique. The cells were observed under invert microscope and scanning electron microscope. The degree of purification was examined by celluar immunochemical stain. The growth curve was tested by thiazolyl blue assay. RESULTS: Over 90% satellite cells were harvested by incontinuous density Percoll gradient centrifugation technique, in contrast to which, only 30%-40% cells were harvested by different adhesion time. Morphological observation accorded with satellite cells. The growth curve indicated that the cells grew in a good status. CONCLUSION: The high purification satellite cells can be obtained by incontinuous density Percoll gradient centrifugation technique. It is a good method to culture seed cells for tissue engineering applications.

Animals↗

PubMed2006

[Application of glycosyl fluorides in the study on glycosidases].

Glycosyl fluorides are becoming increasingly important molecules for the study on glycosidases. Firstly, glycosyl fluorides act as substrates for glycosidases hydrolysis. Scecondly, the installation of fluorine elsewhere on the carbohydrate ring modifies the properties of the glycosyl fluoride so that the resultant compounds act as mechanism-based inhibitors to label enzymes in the active site, allowing identification of the catalytic nucleophile. Furthermore, glycosyl fluorides also act as donors for transglycosylation by retaining glycolides. Finally, glycosyl fluorides of the wrong anomeric configuration could be used by retaining glycosidase mutants such as glycosynthases and thioglycosynthases to synthesize carbohydrate with high yields(normally 60% to approximately 90%). Fundamental and applied research in biology, glycobiology and nanobiotechnology would benefit from the possibility of synthesizing tailor-made oligo-/poly-saccharides.

Animals↗

PubMed2006

[Microsatellite DNA monitoring in inbred cultivation of outbred rats].

Microsatellite DNA was used to monitor the gene inheritance of successive generations of rats. It is useful in selective breeding to quickly bring genes to homozygosity and to shorten the cultivation periods of new inbreeding of rats. Thirty microsatellite DNA loci were PCR amplified to analyze the DNA polymorphism in generational crosses between the outbred Wistar and SD rats. Rats in F generations with a moderate to high coefficient of similarity with the female F0 SD rats were crossed. All loci in the F2 generation were heterozygous and polymorphic. By F9, 27 loci have become homozygotic, with a homozygosity rate of 90%. The coefficient of similarity tended to increase at a rate of 6%-20% with each successive generation. Skin grafting confirmed no rejection among the F9 generation of rats. Therefore we have established a novel method for rapid cultivation of inbred rats.

Animals↗

PubMed2006

[A robust approach to independent component analysis and its application in the analysis of magnetoencephalographic data].

Independent component analysis (ICA) is a new method of signal statistical processing and widely used in many fields. We face several problems such as the different nature of source signals (e.g. both super-Gaussian and sub-Gaussian sources exist), unknown number of sources and contamination of the sensor signals with a high level of additive noise in the analysis of signal. A robust approach was proposed to solve these problems in this paper. Firstly, observations (noisy data) possessing high dimensionality were preprocessed and decomposed into a source signal subspace and a noise subspace. Then the number of sources was got through the cross-validation method, and this solved the problem that ICA could not confirm the number of sources. At last the transformed low-dimensional source signals were further separated with the fast and stable ICA algorithm. Through the analysis of artificially synthesized data and the real-world Magnetoencephalographic data, the efficacy of this robust approach was illustrated.

Algorithms↗

PubMed2006

A point-process model for rapid identification of post-translational modifications.

Post-translational modifications (PTMs) are very important to biological function, and yet are notoriously difficult to detect and identify, especially in a high-throughput manner. Most of the existing approaches rely on exhaustive searches which are highly time consuming and thus are currently limited to handling of a few types of PTMs. In this paper, we present a point-process model that aims to find the optimal mass shifts to maximize the spectra alignment between an experimental MS/MS spectrum and a candidate theoretical spectrum, through cross-correlation calculation, yields a rapid search for all types of PTMs in a blind mode, i.e., without giving the types of the searching PTMs in advance. The test results show that our new approach's performance is comparable to or better than the other blind search methods, but is more efficient computationally and simpler in its concept.

Algorithms↗

PubMed2006

[Temporal and spatial distribution characteristics of nitrogen losses in hilly area of Taihu Lake].

Four typical land uses in hilly area of Taihu Lake were studied on temporal and spatial distribution characteristics of nitrogen losses in surface runoff under natural rainfall through experiment in situ. The medium value of event mean concentration (EMC) of ammonia nitrogen (NH4(+) -N) which dominated agricultural N in surface runoff accounted for 44.5% of total nitrogen (TN), while nitrite nitrogen (NO2(-) -N) accounted for 1.8%. Concentration of nitrogen in runoff had significantly seasonal variation which was related to meteorologic conditions such as rainfall, temperature, and agricultural activities. Temporal variabilities of site mean concentration (SMC) for TN, NH4(+) -N, NO3(-) -N and NO2(-) -N were decreased sequentially. The highest SMC value of TN, NH(+) -N and NO3(-) -N in upland runoff and N2(-) -N in bamboo grove were observed. The spatial distribution of nitrogen losses was determined by fertilizer application and vegetation coverage. Spatial variabilities for SMC of nitrogen were less than temporal variabilities. It was found that transportation fluxes of nitrogen in surface runoff from upland and vegetable plot were higher than that from chestnut orchard and bamboo forest which have significantly related to surface runoff volume.

China↗

PubMed2005

Structural genomics analysis of alternative splicing and application to isoform structure modeling.

Alternative splicing is a sophisticated nuclear process that regulates gene expression. It represents an important mechanism for enhancing the functional diversity of proteins. Our current knowledge of alternatively spliced variants is derived mainly from mRNA transcripts, and very little is known about their protein tertiary structures. We carried out a large-scale analysis of known alternatively spliced variants at both protein sequence and structure levels and have shown that threading is, in general, a viable approach for modeling structures of alternatively spliced variants. An examination of alternative splicing at the protein sequence level revealed that the size of splicing events follows the power law distribution and the majority of splicing isoforms harbor only one or two alternations. We examined alternative splicing in the context of protein 3D structures and found that the boundaries of alternative splicing events generally happen in coil regions of secondary structures and exposed residues and the majority of the sequences involved in splicing are located on the surface of proteins. In light of these findings, we then proceeded to demonstrate that threading represents a useful tool for structure prediction of alternative splicing isoforms and addressed the fold stability issue of threading-based structure prediction by molecular dynamics simulation. Our analysis and the insights gained have helped to establish a viable method for structure prediction of alternatively spliced isoforms at the genome scale.

Alternative Splicing↗

PubMed2005

Post-anthesis development of inferior and superior spikelets in rice in relation to abscisic acid and ethylene.

The purpose of this study was to test the hypothesis that the interaction between abscisic acid (ABA) and ethylene may be involved in mediating the post-anthesis development of spikelets in rice (Oryza sativa L.). Two rice genotypes were field-grown, and the changes of ABA, ethylene, and 1-aminocylopropane-1-carboxylic acid (ACC) levels in spikelets during grain filling and their relationships with endosperm-division and grain-filling rates were investigated. The results showed that earlier-flowering superior spikelets exerted dominance over later-flowering inferior spikelets in endosperm cell-division and grain-filling rates. The two genotypes behaved the same. Later-flowering spikelets had higher levels of ethylene and ACC than earlier-flowering spikelets. The ethylene evolution rate was significantly and negatively correlated with the cell division and grain filling rates. By contrast to ethylene, later-flowering spikelets contained a lower ABA content/concentration and showed a low content ratio of ABA to ACC than earlier-flowering ones. The cell-division and grain-filling rates were significantly and positively correlated with both ABA contents and the ratio of ABA to ACC. Application of cobalt ion (inhibitor of ethylene synthesis) or ABA at an early grain-filling stage significantly increased endosperm cell division rate and cell number, grain-filling rate, and grain weight of inferior spikelets. Application of ethephon (an ethylene-releasing agent) or fluridone (an inhibitor of carotenoid synthesis) had the opposite effect. The results suggest that antagonistic interactions between ABA and ethylene mediate endosperm cell-division and grain-filling in rice. A higher ratio of ABA to ethylene in rice spikelets is required to maintain a faster grain-filling rate.

Abscisic Acid↗

PubMed2005

Tunable asymmetrical Fano resonance and bistability in a microcavity-resonator-coupled Mach-Zehnder interferometer.

We propose a simple microresonator scheme for a Mach-Zehnder interferometer in which a microresonator is side coupled to one arm and a phase shifter is introduced into the other arm, to produce an asymmetric Fano-resonance line shape. In this system, a phase shifter is used to control the variation of the asymmetric line shape, with another reverse resonance next to a resonance minimum over a very narrow frequency range, which results from the interference between a direct channel and a high-Q resonance indirect channel. We also theoretically investigate the novel bistability characteristic based on these shapes.

Journal Article↗

PubMed2005

Liquid chromatography-mass spectrometry method for the determination of nicardipine in human plasma.

A simple and sensitive liquid chromatography-mass spectrometry method is described for the determination of nicardipine in human plasma. Chromatographic separation of the analyte was achieved on a C(18) column using a mobile phase of methanol, water and formic acid (320:180:0.4, v/v/v). Selected ion monitoring (SIM) in positive mode was used for analyte quantification at m/z 480.2 for nicardipine and m/z 256.4 for diphenhydramine. The run time was less than 5 min. The linearity over the concentration range of 0.05-20.0 ng/ml for nicardipine was obtained and the lower limit of quantification was 0.05 ng/ml. For each level of QC samples, inter-day and intra-day precisions (R.S.D.) were < or =9.3 and 11.1%, respectively, and accuracy (RE) was +/-4.9%. The present LC-MS method was successfully applied in the pharmacokinetic studies of nicardipine hydrochloride delayed-release tablets in two formulations after oral administration to healthy volunteers.

Calcium Channel Blockers↗

PubMed2005

[Analgesic effect of intrathecal transplant of immortalized rat astrocyte strain genetically modified by human preproenkephalin gene on rat chronic neuropathic pain].

OBJECTIVE: To observe the analgesic effect of intrathecal transplant of immortalized rat astrocyte genetically modified by human preproenkephalin gene (IAST/hPPE) on chronic neuropathic pain. METHODS: 40 adult male Sprague-Dawley rats were randomly divided into four groups, 10 rats for each group. Naive group, SNI group, SNI + IAST group and SNI + IAST/hPPE group. The immortalized rat astrocyte (IAST) or IAST/hPPE co-incubated with bromodeoxyuridine (BrdU) in vitro were transplanted in the lumbar 4 to 6 subarachnoid space near the spinal cord 1 week after right side spared nerve injury (SNI). All animals were tested for bilateral 50% hindpaw withdrawal threshold (PWT) to a graded series of Von Frey hairs stimulation once a week from one week before SNI to six weeks after transplant, the difference value for right 50% PWT minus left 50% PWT was calculated and the effect of intraperitoneal naloxone on the analgesic efficacies was also observed. The content of L-EK in the spinal cord of L4 - 6 and was determined using immunohistochemistry and radioimmunoassay, and the expression of BrdU in grafts was determined using immunohistochemistry. RESULTS: Allodynia-like behaviour after 1 week following SNI was observed. As compared with Naive group, the difference value for the right 50% PWT minus left 50% PWT in the other three groups was higher significantly (P < 0.01). The tactile allodynia induced by SNI was significantly alleviated during the 1 to 6 week period after transplantation of IAST/hPPE cells, but transplants of IAST cells had no effect on the allodynia-like behaviour. The difference value for the right 50% PWT minus left 50% PWT in SNI + IAST/hPPE group was lower significantly than that in the SNI and SNI +I AST group (P < 0.01), but there was no significant difference between SNI and SNI + IAST group (P > 0.05). The efficacies were reversed by intraperitoneal naloxone in SNI + IAST/hPPE group. The content of L-EK in the lumbar spinal cord in IAST/hPPE group (108.1 pg/mg +/- 12.5 pg/mg) was significantly higher than that in other three groups (P < 0.01), but there was no significant difference between SNI and SNI + IAST group (25.4 pg/mg +/- 1.9 pg/mg vs 28.0 pg/mg +/- 2.1 pg/mg, P > 0.05). Furthermore, The grafts in the surface of dorsal horn were still stained positively for BrdU, they survived greater than 6 weeks on the pia mater around the spinal cord. CONCLUSION: Intrathecal transplant of IAST/hPPE cells could alleviate the allodynia-like behaviour after chronic neuropathic pain, which is associated with enkephalin secreted continuously from the grafts and conducted via opiate receptors.

Animals↗

PubMed2005

[Preliminary research on preparation of porcine bladder acellular matrix graft for tissue engineering applications].

OBJECTIVE: To investigate the preparation method of porcine bladder acellular matrix graft (BAMG) and evaluate the feasibility of using BAMG as biomaterial scaffold to construct tissue engineering bladder. METHODS: Bladders were harvested from adult pigs at a slaughterhouse and were decellularized by the method of enzyme digestion or eradicator washing. The BAMG was then examined by optic microscope and electron microscope to confirm no cell elements remained. The structure of the BAMG was always observed through the Scanning Microscope. The skeletal muscle stem cells of New Zealand white rabbits were implanted in 96-hole-plank and cultured by BAMG extract liquid or normal culture medium. The cytotoxicity of BAMG was tested through MTT assay. New Zealand white rabbits were underwent bladder triangle area spared cystectomy and reconstructed by the heterogeneity BAMG. The animal bladders were obtained after six weeks and the tissue regeneration was examined. RESULTS: Good outcome were obtained with either of the two methods. There were no cell elements remained under the examination of optical microscope and electron microscope. The interstice could observed on BAMG through the Scanning Microscope. The relative growth rate (RGR) was 81%, 88%, 93% and 96% separately on the 2nd, the 4th, the 6th and the 8th day (t = 3.7419, P < 0.025). The cytotoxicity score was I, which indicated that BAMG had a good cytocompatibility. All rabbits were alive except one which died from diarrhea. The reconstructed bladder resumed the construction and function of the bladder. The transitional cells and muscle cells growth could be seen in the scaffold of the repaired bladder after six weeks. CONCLUSION: The porcine BAMG has good biocompatibility and can be used as ideal biomaterial scaffold of bladder tissue engineering.

Animals↗

PubMed2005

Synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccharide residue.

The focus of this work was on the synthesis of two bidesmosidic ursolic acid saponins bearing a 2,3-branched trisaccharide residue. Therefore, 3-O-{[beta-D-glucopyranosyl-(1-->2)]-[alpha-L-arabinopyranosyl-(1-->3)]-alpha-L-arabinopyranosyl}ursolic acid-28-O-[beta-D-glucopyranosyl] ester 1 was concisely synthesized by two strategies in 22% and 41% overall yield, respectively, and another congener 3-O-{[beta-D-xylopyranosyl-(1-->2)]-[beta-D-glucopyranosyl-(1-->3)]-alpha-L-arabinopyranosyl}ursolic acid-28-O-[beta-D-glucopyranosyl] ester 2 was also efficiently prepared in 81% overall yield. The (1)H NMR and (13)C NMR signals of saponin 2 are all consistent with those reported for the natural product.

Carbohydrate Sequence↗

PubMed2005

Determination of roxithromycin in rat lung tissue by liquid chromatography-mass spectrometry.

A liquid chromatography-mass spectrometry (LC-MS) method for the determination of roxithromycin in rat lung tissue is described. Liquid-liquid extraction was adopted for sample preparation with recoveries from 72.5 to 76.9% at levels of 0.1, 5.0 and 20.0 microg/ml. Chromatographic separation was performed on a C18 column using a mixture of methanol, water and formic acid (80:20:1, v/v/v) as mobile phase delivered at a flow rate of 0.5 ml/min. Positive selected ion monitoring (SIM) mode was used for the quantification of roxithromycin at m/z 837.7 and clarithromycin (internal standard) at m/z 748.7. The linearity was obtained over the concentration range of 0.05-20.0 microg/ml and the lower limit of quantification was 0.05 microg/ml. For each QC level of roxithromycin, the intra- and inter-day precisions relative standard deviation (R.S.D.) were less than 4.1 and 7.5%, respectively, and accuracy (RE) was +/-10.0%. The proposed LC-MS method has been successfully used for the determination of roxithromycin in rat lung tissue after oral administration of roxithromycin formulations to 44 SD rats. The present study demonstrates that the concentration of roxithromycin in rat lung tissues can be significantly increased by ambroxol when they are formulated in combination.

Ambroxol↗

PubMed2005

Independently tunable 1.3 W femtosecond Ti:sapphire lasers passively synchronized with attosecond timing jitter and ultrahigh robustness.

A stable passively synchronized femtosecond laser has been realized by coupling two 1.3 W mode-locked Ti:sapphire lasers with a Kerr medium. An ultralong tolerance of 10 microm for the cavity length mismatch and a timing jitter of less than 0.4 fs were obtained. The relative carrier-envelope phase slip was directly observed by measuring the heterodyne output between the two lasers.

Journal Article↗

PubMed2005

Rates of adult schizophrenia following prenatal exposure to the Chinese famine of 1959-1961.

CONTEXT: Schizophrenia is a common major mental disorder. Intrauterine nutritional deficiency may increase the risk of schizophrenia. The main evidence comes from studies of the 1944-1945 Dutch Hunger Winter when a sharp and time-limited decline in food intake occurred. The most exposed cohort conceived during the famine showed a 2-fold increased risk of schizophrenia. OBJECTIVE: To determine whether those who endured a massive 1959-1961 famine in China experienced similar results. DESIGN, SETTING, AND PARTICIPANTS: The risk of schizophrenia was examined in the Wuhu region of Anhui, one of the most affected provinces. Rates were compared among those born before, during, and after the famine years. Wuhu and its surrounding 6 counties are served by a single psychiatric hospital. All psychiatric case records for the years 1971 through 2001 were examined, and clinical and sociodemographic information on patients with schizophrenia was extracted by researchers who were blinded to the nature of exposure. Data on number of births and deaths in the famine years were available, and cumulative mortality was estimated from later demographic surveys. MAIN OUTCOME MEASURES: Evidence of famine was verified, and unadjusted and mortality-adjusted relative risks of schizophrenia were calculated. RESULTS: The birth rates (per 1000) in Anhui decreased approximately 80% during the famine years from 28.28 in 1958 and 20.97 in 1959 to 8.61 in 1960 and 11.06 in 1961. Among births that occurred during the famine years, the adjusted risk of developing schizophrenia in later life increased significantly, from 0.84% in 1959 to 2.15% in 1960 and 1.81% in 1961. The mortality-adjusted relative risk was 2.30 (95% confidence interval, 1.99-2.65) for those born in 1960 and 1.93 (95% confidence interval, 1.68-2.23) for those born in 1961. CONCLUSION: Our findings replicate the Dutch data for a separate racial group and show that prenatal exposure to famine increases risk of schizophrenia in later life.

Adult↗

PubMed2005

Endomorphin 1[psi] and endomorphin 2[psi], endomorphins analogues containing a reduced (CH2NH) amide bond between Tyr1 and Pro2, display partial agonist potency but significant antinociception.

Endomorphin 1 (EM1) and endomorphin 2 (EM2) are highly potent and selective mu-opioid receptor agonists and have significant antinociceptive action. In the mu-selective pocket of endomorphins (EMs), Pro2 residue is a spacer and directs the Tyr1 and Trp3/Phe3 side chains into the required orientation. The present work was designed to substitute the peptide bond between Tyr1 and Pro2 of EMs with a reduced (CH2NH) bond and study the agonist potency and antinociception of EM1[psi] (Tyr[psi(CH2NH)]Pro-Trp-Phe-NH2) and EM2[psi] (Tyr[psi(CH2NH)]Pro-Phe-Phe-NH2). Both EM1[psi] and EM2[psi] are partial mu opioid receptor agonists showing significant loss of agonist potency in GPI assay. However, EMs[psi] exhibited potent supraspinal antinociceptive action in vivo. In the mice tail-flick test, EMs[psi] (1, 5, 10 nmol/mouse, i.c.v.) produced potent and short-lasting antinociception in a dose-dependent and naloxone (1 mg/kg) reversed manner. At the highest dose of 10 nmol, the effect of EM2[psi] was prolonged and more significant than that of EM2. In the rat model of formalin injection induced inflammatory pain, EMs[psi] (0.1, 1, 10 nmol/rat, i.c.v.), like EMs, exerted transient but not dose-dependent antinociception. These results suggested that in the mu-selective pocket of EMs, the rigid conformation induced by the peptide bond between Tyr1 and Pro2 is essential to regulate their agonist properties at the mu opioid receptors. However, the increased conformational flexibility induced by the reduced (CH2NH) bond made less influence on their antinociception.

Amides↗

PubMed2005

Current preventive treatment for recurrence after curative hepatectomy for liver metastases of colorectal carcinoma: a literature review of randomized control trials.

To review the preventive approaches for recurrence after curative resection of hepatic metastases from colorectal carcinoma, we have summarized all available publications reporting randomized control trials (RCTs) covered in PubMed. The treatment approaches presented above include adjuvant intrahepatic arterial infusion chemotherapy, systemic chemotherapy, neoadjuvant chemotherapy, and immunotherapy. Although no standard treatment has been established, several approaches present promising results, which are both effective and tolerable in post-hepatectomy patients. Intrahepatic arterial infusion chemotherapy should be regarded as effective and tolerable and it increases overall survival (OS) and disease-free survival (DFS) of patients, while 5-fluorouracil-based systemic chemotherapy has not shown any significant survival benefit. Fortunately chemotherapy combined with hepatic arterial infusion and intravenous infusion has shown OS and DFS benefit in many researches. Few neoadjuvant RCT studies have been conducted to evaluate its effect on prolonging survivals although many retrospective studies and case reports are published in which unresectable colorectal liver metastases are downstaged and made resectable with neoadjuvant chemotherapy. Liver resection supplemented with immunotherapy is associated with optimal results; however, it is also questioned by others. In conclusion, several adjuvant approaches have been studied for their efficacy on recurrence after hepatectomy for liver metastases from colorectal cancer (CRC), but multi-centric RCT is still needed for further evaluation on their efficacy and systemic or local toxicities. In addition, new adjuvant treatment should be investigated to provide more effective and tolerable methods for the patients with resectable hepatic metastases from CRC.

Colonic Neoplasms↗