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Biomedical subjects

Peng Li

Publications and source records attributed to Peng Li.

At least 73 records · Page 4Linked to original sources
PubMed2006

Anti-apoptotic hPEBP4 silencing promotes TRAIL-induced apoptosis of human ovarian cancer cells by activating ERK and JNK pathways.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis in a variety of tumor cell lines but not typically in normal or nontransformed cells, which makes TRAIL a desirable therapeutic agent to fight cancer. Human phosphatidylethanolamine-binding protein 4 (hPEBP4) is a recently identified anti-apoptotic molecule and has been shown to be highly expressed in breast and ovarian cancer cells. We demonstrate that silencing of hPEBP4 in CaoV-3 ovarian cancer cells potentiates TRAIL-induced apoptosis. We found that endogenous hPEBP4 interacts with Raf-1 and MEK1 in TRAIL-treated CaoV-3 cells by co-immunoprecipitation analysis. Simultaneously, silencing of hPEBP4 in CaoV-3 cells enhances TRAIL-induced ERK and JNK activation. Moreover, the inhibitors of MEK1 or JNK can reduce hPEBP4-silence-induced TRAIL sensitivity. Therefore, silencing of hPEBP4 in CaoV-3 ovarian cancer promotes TRAIL-induced apoptosis, and the increased MAPK activation is required for the apoptosis sensitization. All these data indicate that silencing of hPEBP4, an important potential target, may be a promising approach for the treatment of ovarian cancer.

Apoptosis↗
PubMed2006

[Evaluation of tympanoplasty with reconstruction of the external canal after mastoidectomy for cholesteatoma].

OBJECTIVE: To investigate the method to repair the deletion of external canal and opened mastoid space after mastoidectomy. METHOD: One stage tympanoplasty with reconstruction of the external canal with temporal cortex was completed in 58 cases (58 ears) with cholesteatoma. RESULT: During the follow-up ranging from one to three years, there was only one relapse. The configuration of external canal was almost normal and pneumatic mastoid space was maintained. Hearing was improved over 30dB in five ears, 20 to 29 dB in 11 ears, 10 to 19 dB in 30 ears, less 10 dB in eight ears and hearing wasn't improved in four ears. CONCLUSION: One stage tympanoplasty with reconstruction of the external canal after mastoidectomy for cholesteatoma is a practical way to improve hearing and decrease recurrence.

Adolescent↗
PubMed2006

[Correlation of antitumor drug sensitivity between marrow mesenchymal stem cells (MSCs) and hepatocarcinoma cells in rats].

BACKGROUND & OBJECTIVE: As hepatocarcinoma stem cells may originate from oval cells and oval cells are difficult to be separated and purified, MSCs (marrow mesenchymal stem cells), which are the progenitor cells of the hepatocarcinoma stem cells, were selected instead in our study to investigate the correlation of anticancer drug sensitivity between hepatocarcinoma cells and MSCs in rats. METHODS: The primary liver carcinoma modle of rats was induced by diethylnitrosamine. Tumor cells and MSCs from eight hepatocarcinoma rats were separated. The inhibitory effects of 3 anticancer drugs [adriacin (0.04 microg/ml), cisplatin (0.2 microg/ml) and fluorouracil (1 microg/ml)] to hepatocarcinoma cells and MSCs were measured by MTT assay. The weight of the tumor in nude mice which were injected with rat hepatocarcinoma cells was measured after 6 weeks. Then the correlation of the inhibitory ratio of 3 anticancer drugs to hepatocarcinoma cells and MSCs, and to the tumor weight of nude mice was analyzed. RESULTS: No correlation was revealed between the inhibitory ratio of 3 anticancer drugs to hepatocarcinoma cells and the tumor weights of nude mice injectal with drug treated tumor cells. The correlation coefficient was: 0.6307 (adriacin, P>0.05), 0.4358 (fuiorouracil, P>0.05) and 0.7080 (cisplatin, P>0.05). No correlation was observed between the inhibitory ratio of 3 anticancer drugs to hepatocarcinoma cells and to MSCs. The correlation coefficient was: 0.6316 (adriacin, P>0.05), 0.4214 (fluorouracil, P>0.05) and 0.5943 (cisplatin, P>0.05). However, significant reverse correlation was found between the inhibitory ratio of 3 anticancer drugs to MSCs and the tumor weights of nude mice injectal with drug treated tumor cells. The correlation coefficient was: -0.8308 (adriacin, P<0.05), -0.8991 (fluorouracil, P<0.01) and -0.8311 (cisplatin, P<0.05). CONCLUSIONS: Conventional anticancer drug sensitivity experiments could not reflect the chemoresistance of the hepatocarcinoma cells. However the inhibitory ratio of the anticancer drugs to MSCs in the hepatocarcinoma rats can reflect the chemoresistance of hepatocarcinoma cells accordingly.

Animals↗
PubMed2006

[Interventional effect of behaviour psychotherapy on patients with premature ejaculation].

OBJECTIVE: To investigate the interventional effect of comprehensive behaviour psychotherapy on the ejaculatory latency of premature ejaculation (PE) patients, sexual satisfaction of sexual partners, as well as its influence on the results of clinical treatment. METHODS: Ninety PE patients were randomly divided into a psychological intervention group (n = 45) and a control group (n = 45). Both groups were given medicine therapy, and the former also received comprehensive behaviour psychotherapy for 6 weeks. All the patients were assessed with the Chinese index of sexual function for PE and ejaculatory latency in the vagina, and the clinical efficacy was compared between the two groups. RESULTS: Before treatment, the ejaculatory latency in the vagina was (0.69 +/- 0.25) min and (0.71 +/- 0.19) min respectively in the intervention and the control groups, as compared with (5.87 +/- 0.59) min and (4.76 +/- 0.54) min before treatment, with significant difference (P < 0.01). In the intervention group, the scores in the control of ejaculatory reflex, the sexual satisfaction of the patients and their sexual partners and anxiety or depress in sexual activity in CIPE were higher than in the control group, with significant difference between the two groups (t = 2.12, 2.31, 2.01, 2.24, P < 0.05). The difference in the SAS score after therapy was of significance (P < 0.01). A month after treatment, the effectivity rates of the two groups were 82.9% and 30% respectively, and the difference was significant (P < .01). CONCLUSION: Comprehensive behaviour psychotherapy obviously adds to the clinical efficacy of drugs in the treatment of PE.

Ejaculation↗
PubMed2006

[Studies on HPLC fingerprint of cortex moutan].

OBJECTIVE: To establish a HPLC fingerprint for quality evaluation of Cortex Moutan. METHOD: The HPLC chromatographic fingerprinting of 30 lots of Cortex Moutan was established and major peaks were identified by LC-MS and MS-MS. RESULT: The HPLC fingerprint of Cortex Moutan was established, showing 15 characteristic peaks. The areas of these peaks were found to complied with the following rule: paeonol > 1, 2, 3, 4, 6-penta-O-galloyl-glucos > methyl gallate > galloylpaeoniflorin > gallic acid > oxypaeoniflorin > other compounds. CONCLUSION: The chromatographic fingerprinting of Cortex Moutan with high specificity can be used to control its quality and monitor lot to lot consistency.

Acetophenones↗
PubMed2005

Interruption of homologous desensitization in cyclic guanosine 3',5'-monophosphate signaling restores colon cancer cytostasis by bacterial enterotoxins.

Bacterial diarrheagenic heat-stable enterotoxins induce colon cancer cell cytostasis by targeting guanylyl cyclase C (GCC) signaling. Anticancer actions of these toxins are mediated by cyclic guanosine 3',5'-monophosphate (cGMP)-dependent influx of Ca2+ through cyclic nucleotide-gated channels. However, prolonged stimulation of GCC produces resistance in tumor cells to heat-stable enterotoxin-induced cytostasis. Resistance reflects rapid (tachyphylaxis) and slow (bradyphylaxis) mechanisms of desensitization induced by cGMP. Tachyphylaxis is mediated by cGMP-dependent protein kinase, which limits the conductance of cyclic nucleotide-gated channels, reducing the influx of Ca2+ propagating the antiproliferative signal from the membrane to the nucleus. In contrast, bradyphylaxis is mediated by cGMP-dependent allosteric activation of phosphodiesterase 5, which shapes the amplitude and duration of heat-stable enterotoxin-dependent cyclic nucleotide accumulation required for cytostasis. Importantly, interruption of tachyphylaxis and bradyphylaxis restores cancer cell cytostasis induced by heat-stable enterotoxins. Thus, regimens that incorporate cytostatic bacterial enterotoxins and inhibitors of cGMP-mediated desensitization offer a previously unrecognized therapeutic paradigm for treatment and prevention of colorectal cancer.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed2005

Multivalent avimer proteins evolved by exon shuffling of a family of human receptor domains.

We have developed a class of binding proteins, called avimers, to overcome the limitations of antibodies and other immunoglobulin-based therapeutic proteins. Avimers are evolved from a large family of human extracellular receptor domains by in vitro exon shuffling and phage display, generating multidomain proteins with binding and inhibitory properties. Linking multiple independent binding domains creates avidity and results in improved affinity and specificity compared with conventional single-epitope binding proteins. Other potential advantages over immunoglobulin domains include simple and efficient production of multitarget-specific molecules in Escherichia coli, improved thermostability and resistance to proteases. Avimers with sub-nM affinities were obtained against five targets. An avimer that inhibits interleukin 6 with 0.8 pM IC50 in cell-based assays is biologically active in two animal models.

Animals↗
PubMed2005

Dominant negative mutation of the TGF-beta receptor blocks hypoxia-induced pulmonary vascular remodeling.

The present study utilized a novel transgenic mouse model that expresses an inducible dominant negative mutation of the transforming growth factor (TGF)-beta type II receptor (DnTGFbetaRII mouse) to test the hypothesis that TGF-beta signaling plays an important role in the pathogenesis of chronic hypoxia-induced increases in pulmonary arterial pressure and vascular and alveolar remodeling. Nine- to 10-wk-old male DnTGFbetaRII and control nontransgenic (NTG) mice were exposed to normobaric hypoxia (10% O2) or air for 6 wk. Expression of DnTGFbetaRII was induced by drinking 25 mM ZnSO4 water beginning 1 wk before hypoxic exposure. Hypoxia-induced increases in right ventricular pressure, right ventricular mass, pulmonary arterial remodeling, and muscularization were greatly attenuated in DnTGFbetaRII mice compared with NTG controls. Furthermore, the stimulatory effects of hypoxic exposure on pulmonary arterial and alveolar collagen content, appearance of alpha-smooth muscle actin-positive cells in alveolar parenchyma, and expression of extracellular matrix molecule (including collagen I and III, periostin, and osteopontin) mRNA in whole lung were abrogated in DnTGFbetaRII mice compared with NTG controls. Hypoxic exposure had no effect on systemic arterial pressure or heart rate in either strain. These data support the hypothesis that endogenous TGF-beta plays an important role in pulmonary vascular adaptation to chronic hypoxia and that disruption of TGF-beta signaling attenuates hypoxia-induced pulmonary hypertension, right ventricular hypertrophy, pulmonary arterial hypertrophy and muscularization, alveolar remodeling, and expression of extracellular matrix mRNA in whole lung.

Actins↗
PubMed2005

Assessing functioning of the prefrontal cortical subregions with auditory evoked potentials in sleep-wake cycle.

Our previously observations showed that the amplitude of cortical evoked potentials to irrelevant auditory stimulus (probe) recorded from several different cerebral areas was differentially modulated by brain states. At present study, we simultaneously recorded auditory evoked potentials (AEPs) from the dorsolateral prefrontal cortex (DLPFC) and the ventromedial prefrontal cortex (VMPFC) in the freely moving rhesus monkey to investigate state-dependent changes of the AEPs in the two subregions of prefrontal cortex. AEPs obtained during passive wakefulness (PW), active wakefulness (AW), slow wave sleep (SWS) and rapid-eye-movement sleep (REM) were compared. Results showed that AEPs from two subregions of prefrontal cortex were modulated by brain states. Moreover, a significantly greater increase of the peak-to-peak amplitude (PPA) of N1-P1 complexes appears in the DLPFC during PW compared to that during AW. During REM, the PPA of N1-P1 complexes presents a contrary change in the two subregions with significant difference: a significant increase in the DLPFC and a slight decrease in the VMPFC compared to that during AW. These results indicate that the modulation of brain states on AEPs from two subregions of the prefrontal cortex investigated is also not uniform, which suggests that different subregions of the prefrontal cortex have differential functional contributions during sleep-wake cycle.

Animals↗
PubMed2005

Simultaneous quantification of cryptotanshinone and its active metabolite tanshinone IIA in plasma by liquid chromatography/tandem mass spectrometry (LC-MS/MS).

A rapid and sensitive method for the simultaneous determination of cryptotanshinone and its active metabolite tanshinone IIA in rat plasma was developed and well validated, using high-performance liquid chromatographic separation with tandem mass spectrometric detection. This method entailed a single step of liquid-liquid extraction with ethyl acetate from a small volume of plasmas. The analytes and internal standard diazepam were baseline separated on a Shim-pack VP-ODS analytical column. Detection was performed on a triple quadrupole tandem mass spectrometer equipped with electrospray ionization source operated under selected reaction monitoring (SRM) mode. The method was linear in the concentration range of 1-100 ng/ml for both tanshinone IIA and cryptotanshinone. The intra- and inter-day precisions (R.S.D.%) were within 10.2% for both analytes. Deviation of the assay accuracies was within +/-12.0% for both analytes. Both analytes were proved to be stable during all sample storing, preparation and analytic procedures. The method was successfully applied to a pharmacokinetic study after an oral administration of cryptotanshinone to rats with a dose of 20 mg/kg. With the lower limits of quantification at 1.0 ng/ml for tanshinone IIA and 0.2 ng/ml for cryptotanshinone, this method was proved to be sensitive enough and reproducible for the pharmacokinetics study of both tanshinones.

Abietanes↗
PubMed2005

Simultaneous determination of tanshinone IIA and cryptotanshinone in rat plasma by liquid chromatography-electrospray ionisation-mass spectrometry.

Tanshinone IIA (TS) and cryptotanshinone (CT) are the major active constituents contained in Radix salvia miltiorrhiza. This paper described a rapid, sensitive and specific assay for the simultaneous quantitative determination of TS and CT in rat plasma. After a single step of liquid-liquid extraction, plasma samples were analyzed by high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) using a reversed-phase C18 column (150 mmx2.0 mm, 5 microm, Shim-pack VP-ODS column). The assay was linear in the concentration range of 2-200 ng/ml. The lower limits of quantification of TS and CT were 1 and 0.2 ng/ml, respectively. Recoveries of TS and CT were greater than 80%. The precisions and accuracies determined from 5 days were all within 12%. The assay was applied to a pharmacokinetic study in rats after an oral administration of total tanshinones with a dose of 150 mg/kg (containing 12% of TS and CT). Results showed that this simple and rapid method was sensitive enough to follow the plasma levels of TS and CT in rats, even though the concentration maximums of both were below 20 ng/ml after an oral administration of total tanshinones.

Abietanes↗
PubMed2005

Atomic-scale study of in situ metal nanoparticle synthesis in a Ni/TiO2 system.

The nucleation and evolution of Ni nanoparticles during reduction of a Ni(NO3)2.6H2O precursor supported on a commercial titania substrate have been studied in situ at atomic resolution using environmental transmission electron microscopy. An incipient wetness technique was used to prepare the starting unreduced material (10 wt % Ni precursor on titania). The Ni precursor, before reduction, shows a nonuniform distribution over the titania support. It is observed that upon reduction, the initial Ni "seed" crystal nucleates within the precursor patch. The distribution and size of the Ni nanoparticles thus generated are influenced by the distribution and size of the precursor patches. In this system, we see no evidence of preferential nucleation of Ni particles on anatase or rutile. At 350 degrees C with CO as the reducing agent, the {111} surface facets of the Ni nanoparticles are predominant during the initial stage of nucleation and growth. However, the {111} facets are partially consumed with time, indicating that they are not thermodynamically favored in the CO atmosphere. In CO and H2 atmospheres, Ni particles show a nonwetting morphology on titania, while in a mild oxidizing environment, a thin layer of NiOx is formed, thus giving rise to a morphology that is indicative of wetting of the support. This work provides fundamental information on understanding and controlling the important parameters involved in the preparation of a well-designed supported Ni catalyst using the incipient wetness technique.

Journal Article↗
PubMed2005

Growth of uniformly aligned ZnO nanowire heterojunction arrays on GaN, AlN, and Al0.5Ga0.5N substrates.

Vertically aligned single-crystal ZnO nanorods have been successfully fabricated on semiconducting GaN, Al0.5Ga0.5N, and AlN substrates through a vapor-liquid-solid process. Near-perfect alignment was observed for all substrates without lateral growth. Room-temperature photoluminescence measurements revealed a strong luminescence peak at approximately 378 nm. This work demonstrates the possibility of growing heterojunction arrays of ZnO nanorods on AlxGa1-xN, which has a tunable band gap from 3.44 to 6.20 eV by changing the Al composition from 0 to 1, and opens a new channel for building vertically aligned heterojunction device arrays with tunable optical properties and the realization of a new class of nanoheterojunction devices.

Aluminum Compounds↗
PubMed2005

Cardiovascular dysfunction caused by cecal ligation and puncture is attenuated in CD8 knockout mice treated with anti-asialoGM1.

The present study was designed to assess hemodynamics and myocardial function at 18 h after injury caused by cecal ligation and puncture (CLP) in CD8-knockout mice treated with anti-asialoGM1 (CD8KO/alphaAsGM1 mice). Arterial pressure was measured by carotid artery cannulation, and left ventricular pressure-volume measurements were obtained by use of a 1.4-Fr conductance catheter. Blood acid-base balance and indexes of hepatic, renal, and pulmonary injury were also measured. CD8KO/alphaAsGM1 mice exhibited higher mean arterial pressure and increased systemic vascular resistance compared with wild-type mice. Cardiac output was significantly decreased in wild-type, but not CD8KO/alphaAsGM1, mice compared with sham controls. Myocardial function was better preserved in CD8KO/alphaAsGM1 mice as indicated by less impairment of left ventricular pressure development over time, time varying maximum elastance, end-systolic pressure-volume relationship, and preload recruitable stroke work. The impairment in myocardial function was associated with induction of proinflammatory cytokine mRNAs in the hearts of wild-type mice. The hemodynamic derangements in wild-type mice were coupled with significant metabolic acidosis and elevated serum creatinine levels. Overall, this study shows that cardiovascular collapse and shock characterized by hypotension, myocardial depression, low systemic vascular resistance, and metabolic acidosis occurs after CLP in wild-type mice but is attenuated in CD8KO/alphaAsGM1 mice. These observations likely explain, in part, the previously observed survival advantage of CD8KO/alphaAsGM1 mice following CLP.

Acid-Base Equilibrium↗
PubMed2005

Manipulation and spectroscopy of a single particle by use of white-light optical tweezers.

We demonstrate, for the first time to our knowledge, three-dimensional (3D) trapping and manipulation of microscopic objects by use of supercontinuum white light generated from photonic crystal fibers. Furthermore, we show that the supercontinuum white-light optical tweezers used have the unique capability to perform optical scattering spectroscopy of a single 3D trapped object over a broad wavelength range. These novel tweezers can potentially open a promising avenue toward simultaneous manipulation and characterization of microscopic objects.

Equipment Design↗
PubMed2005

Nociceptin in rVLM mediates electroacupuncture inhibition of cardiovascular reflex excitatory response in rats.

Electroacupuncture (EA) at Neiguan-Jianshi acupoints through an opioid mechanism inhibits the cardiovascular pressor response induced by mechanical stimulation of the stomach. Because nociceptin also may regulate cardiovascular activity through its action in the brain stem, we hypothesized that this neuromodulator serves a role in the EA-related inhibitory effect. Blood pressure in ventilated male Sprague-Dawley rats (400-600 g) anesthetized by ketamine and alpha-chloralose was measured during balloon inflation of the stomach. Gastric distension with 6-8 ml of air induced consistent pressor reflexes of 26 +/- 1 mmHg that could be repeated every 10 min for 100 min. When nociceptin (10 nM) was microinjected into the rostral ventrolateral medulla (rVLM), the pressor response induced by gastric distension was inhibited by 68 +/- 6%. Thirty minutes of EA also decreased the reflex response by 75 +/- 11%; microinjection of saline into the rVLM did not alter the inhibitory effect of EA. In contrast, microinjection of a nociceptin receptor antagonist into the rVLM promptly reversed the EA response. Pretreatment with the opioid receptor antagonist naloxone did not influence the EA-like inhibitory effect of nociceptin on the distension-induced pressor reflex (22 +/- 1 to 8 +/- 2 mmHg). Furthermore, a mu-opioid receptor agonist microinjected into the rVLM after microinjection of a nociceptin receptor antagonist during EA promptly reversed the nociceptin receptor antagonist-related inhibition of the EA effect. Thus, in addition to the classical opioid system, nociceptin, through opioid receptor-like-1 receptor stimulation in the rVLM, participates in the modulatory influence of EA on reflex-induced increases in blood pressure.

Animals↗
PubMed2005

Small nonphosphorylated Grb2-SH2 domain antagonists evaluated by surface plasmon resonance technology.

The growth factor receptor-binding protein-Src homology 2 (Grb2-SH2) domain plays an important role in the oncogenic Ras signal transduction pathway, which involves cell proliferation and differentiation. Therefore, the Grb2-SH2 domain has been chosen as our target for development of potential antiproliferative agents. Herein, we report the study of the inhibitory effects of small nonphosphorylated peptide analogs interacting with the Grb2-SH2 domain protein by surface plasmon resonance (SPR) technology. A set of 8 related peptide analogs were synthesized, purified, and characterized. Their inhibitory effects on Grb2-SH2 were evaluated by the SPR technology developed with the BIACORE X instrument. The lead peptide, Fmoc-Glu-Tyr-Aib-Asn-NH2 (Fmoc-E-Y-Aib-N; Fmoc: 9-fluorenylmethyoxycarbonyl; Aib=alpha-amino isobutyric acid) inhibited Grb2-SH2 domain function with an IC50 value of 8.7 microM. A molecular modeling study of the lead peptide indicated that the glutamate in the Fmoc peptide is ideally positioned to form a strong salt bridge to Arg 67 in the Grb2-SH2 domain, using both its backbone carbonyl and its acidic group. Residue Glu 89 in Grb2-SH2 flips inward to fill the binding site and partially replace the phosphate group as a hydrogen-bond acceptor. Results of these studies provide important information for further development of potent nonphosphorylated peptide inhibitors of the Grb2-SH2 domain.

Drug Evaluation, Preclinical↗