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Biomedical subjects

Peng Sun

Publications and source records attributed to Peng Sun.

At least 37 records · Page 2Linked to original sources
PubMed2005

The controlled evolution of a polymer single crystal.

We present a method for controlling the initiation and kinetics of polymer crystal growth using dip-pen nanolithography and an atomic force microscope tip coated with poly-dl-lysine hydrobromide. Triangular prisms of the polymer epitaxially grow on freshly cleaved mica substrates, and their in-plane and out-of-plane growth rates can be controlled by raster scanning the coated tip across the substrate. Atomic force microscope images were concomitantly recorded, providing a set of photographic images of the process as it spans the nanometer- to micrometer-length scales as a function of environmental conditions.

Aluminum Silicates↗
PubMed2005

Assays for functional properties of Rab34 in macropinosome formation.

We have shown that Rab34/Rah participates in the promotion of macropinosome formation. Here we describe procedures for the analyses of intracellular localization and some functional properties of Rab34. Rab34 lacks a consensus sequence of the fourth motif for GTP/GDP binding and GTPase activities. Indeed, GTPase assay shows that wild-type Rab34 has extremely weak GTPase activity in vitro. However, Rab34 exhibits appreciable GTPase activity in vivo probably due to the presence of specific GTPase-activating protein (GAP) activity in cells. Specific intracellular localization of Rab34 is easily detected by the expression of epitope-tagged or enhanced green fluorescent protein (EGFP)-tagged protein. It is colocalized with actin filaments to membrane ruffles and membranes of nascent macropinosomes, which are formed from the ruffles. By contrast, Rab5 is not associated with the ruffles or nascent macropinosomes but present in endosomes at later stages. The function of Rab34 in macropinosome formation is analyzed by the transfection of wild-type, constitutively active, and dominant-negative mutants of Rab34 in fibroblasts followed by treatment with platelet-derived growth factor (PDGF) or phorbol ester. These analyses indicate that Rab34 is required for efficient macropinosome formation.

Amino Acid Sequence↗
PubMed2005

Bioactive asterosaponins from the starfish Culcita novaeguineae.

Two new sulfated steroidal pentaglycosides (asterosaponins), novaeguinosides I (2) and II (3), along with the known regularoside B (1) were isolated from the starfish Culcita novaeguineae. Their structures were elucidated by extensive NMR techniques as well as chemical evidence. The new asterosaponins showed marginal in vitro cytotoxicity against two human tumor cell lines.

Animals↗
PubMed2005

Three new asterosaponins from the starfish Culcita novaeguineae and their bioactivity.

Bioassay-guided fractionation of the active n-BuOH extract of the starfish Culcita novaeguineae resulted in the isolation of three new sulfated steroidal glycosides (asterosaponins) 1, 2 and 3, as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. Compounds 1-3 possess the same pentasaccharide moiety, beta-D-fucopyranosyl-(1-->2)-alpha-L-arabinopyranosyl-(1-->4)-[beta-D-quinovopyranosyl-(1-->2)]-beta-D-xylopyranosyl-(1-->3)-beta-D-quinovopyranosyl, linked to C-6 of 3beta-sulfated steroidal aglycones and differ from each other in the side chains. Their structures were elucidated by extensive spectral studies and chemical evidences. Saponins 1 and 3 showed significant cytotoxicity against two cancer cell lines (IC50 values for 1:3.57 microg/mL [K-562], 2.55 microg/mL [BEL-7402]; for 3:3.75 microg/mL [K-562], 1.89 microg/mL [BEL-7402]), as well as hemolytic activity to rabbit erythrocytes (ED50 values: 16 and 31 microg/mL, respectively), while 2 was inactive in these bioassays.

Animals↗
PubMed2005

[Effects of yiqi huayu recipe and its decomposed formulas on apoptosis-related factors of anulus fibrosus cells in rats].

OBJECTIVE: To study the effects of Yiqi Huayu Recipe and its decomposed formulas-medicated sera on expressions of bcl-2, Bax and caspase-8 of apoptotic anulus fibrosus cells in rats. METHODS: Immunohistochemical and integral optical density analytic methods were used to observe the effects of Yiqi Huayu Recipe-, Yiqi Recipe-, Huayu Recipe-medicated sera and insulin-like growth factor 1 (IGF-1) on the expressions of bcl-2, Bax and caspase-8 of apoptotic anulus fibrosus cells in rats induced by anti-Fas antibody. RESULTS: As compared with apoptosis group, bcl-2 expression was higher, Bax and caspase-8 expressions were lower in Yiqi Huayu-treated, Yiqi-treated, Huayu-treated and IGF-1 groups (P<0.01). As compared with Yiqi-treated group and Huayu-treated group, Bax expression was lower in Yiqi Huayu-treated group (P<0.05). CONCLUSION: Yiqi Huayu Recipe and its decomposed formulas can delay degeneration of the cervical intervertebral disc, which may be due to its action in regulating the expressions of bcl-2, Bax and caspase-8.

Animals↗
PubMed2005

PE, a new sulfated saponin from sea cucumber, exhibits anti-angiogenic and anti-tumor activities in vitro and in vivo.

Here, we examined the in vitro and in vivo anti-angiogenesis and anti-tumor activities of PE, a new marine-derived compound. Inhibition of angiogenesis was assessed in vitro using proliferation, migration, adhesion, tube-formation and apoptosis assays in PE-treated HMECs and HUVECs. In vivo, CAM assays were used to assess inhibition effect of PE on physiological angiogenesis, and immunofluorescent microscopy was used to examine tumor microvessel density and apoptosis in PE-treated mouse tumor models. Finally, Western blotting analyses were performed to examine the effect of PE on VEGF signaling in HMECs. The results showed that PE inhibited proliferation of HMECs and HUVECs with IC50 values of 2.22 +/- 0.31 microM and 1.98 +/- 0.32 microM, induced endothelial cell apoptosis at concentrations <2 microM, induced dose-dependent suppression of cell migration, cell adhesion and tube formation in HMECs and HUVECs, and showed anti-proliferative activities against several tumor cell lines (IC50 values of approximately 4 microM). In vivo, PE (5 nM/egg) suppressed spontaneous angiogenesis in our CAM assay, and induced marked growth inhibition in mouse sarcoma 180 and hepatoma 22 models. Specifically, PE treatment reduced mouse sarcoma 180 tumor volume by triggering apoptosis of both tumor and tumor-associated endothelial cells, preferentially targeting on endothelial cells comparable with tumor cells. Finally, PE treatment suppressed the active (phosphorylated) forms of VEGFR2, Akt, ERK, FAK and paxillin, which are involved in endothelial cell survival, proliferation, adhesion and migration. Our results indicate that PE exerts an anti-angiogenic activity associated with inhibition of VEGFR2 signaling, and an anti-tumor activity associated with decreased proliferation of tumor cells and increased apoptosis of both endothelial cells and tumor cells.

Angiogenesis Inhibitors↗
PubMed2005

[Effects of Yiqi Huayu Recipe on gene expression pattern of normal and apoptotic chondrocytes in cervical intervertebral disc in rats].

OBJECTIVE: To study the effects of Yiqi Huayu Recipe on the gene expression pattern in normal and apoptotic chondrocytes in the cervical intervertebral disc of rats. METHODS: The intervertebral disc endplates of rats were digested enzymatically. The apoptosis of the chondrocytes was induced by anti-Fas antibody. BiostarR-40s microarray chips were used to investigate the gene expression pattern in chondrocytes in the normal control, apoptosis and Yiqi Huayu Recipe groups. The results were scanned with Scan Array 4000 and analyzed with GenePix Pro 3.0, and then subjected to standardization and ratio analysis. RESULTS: In the apoptosis group, 30 kinds of genes expressed in cervical intervertebral disc chondrocytes were screened out, in which 10 were up-regulated (ratio>2) and 20 down-regulated (ratio<0.5) as compared with the normal control group. On the other hand, in the Yiqi Huayu Recipe group, 97 kinds of genes expressed in cervical intervertebral disc chondrocytes were screened out, in which 44 were up-regulated (ratio>2) and 53 down-regulated (ratio<0.5) as compared with the apoptosis group. CONCLUSION: There are some signal transduction pathways that control the apoptosis of the intervertebral disc chondrocytes. Yiqi Huayu Recipe regulates the gene express of the apoptotic chondrocytes in intervertebral disc. The study gives a further understanding to the mechanism of the cervical spondylosis and enriches the theories of qi and blood of traditional Chinese medicine.

Animals↗
PubMed2004

[Psychological hindrance and its treatment in chronic prostatitis patients].

OBJECTIVE: To improve the knowledge of psychological hindrance in chronic prostatitis (CP) patients and study the treatment strategy of it. METHODS: Two hundred and fifty-eight CP patients with psychological hindrance, aged 16 to 65 years (average 33 years), were divided into the psychotherapy group (148 cases) and the control (110 cases). The control were only treated with antibiotics and Chinese traditional medicines, while the psychotherapy group were treated with cognitive therapy besides the above medicines. RESULTS: The symptoms in the psychotherapy group were improved obviously compared with those in the control. Both the cure rate (P < 0.05) and the effective rate (P < 0.001) of the psychotherapy group were higher than those of the control. CONCLUSION: Psychotherapy is an effective way to treat CP patient with psychological hindrance.

Adolescent↗
PubMed2004

[Identification of bryostatins in Bugula neritina extracts by high performance liquid chromatography and Q-Tof mass spectrometry].

A method with tandem high performance liquid chromatography (HPLC) and Q-Tof mass spectrometry (MS) has been established for the qualitative assay of bryostatins in Bugula neritina extracts. Ten bryostatins were well separated on a Polaris C18-5 column (4.6 mm i.d. x 200 mm, 5 microm) with methanol and water (80:20, v/v) as mobile phase. The bryostatins were qualitatively detected with the mass spectrometric detection. Ten bryostatins were found in the Bugula neritina collected from Gulf of Dayawan (Shenzhen, China). Mass spectra of the peaks led to the identification of nine known bryostatins that were bryostatins 4, 5, 6(9), 7, 8, 10, 16, 17, 18. Bryostatins 4, 5, 8, 10 could be further verified by the retention times of the corresponding standards. The two trace constituents, bryostatin 7 and 17, were for the first time found in Bugula neritina inhabiting in China sea. It is interesting that the result indicated the existence of a possibly new bryostatin in the mixture. The work above provides a quick and accurate assay method for the qualitative identification of the bryostatins in Bugula neritina extracts.

Animals↗
PubMed2003

Studies of effect of phase volume ratio on transfer of ionizable species across the water/ 1,2-dichloroethane interface by a three-electrode setup.

The electrochemical behavior of pyridine distribution at the water/1,2-dichloroethane interface with variable phase volume ratios (r = Vo/Vw) was investigated by cyclic voltammetry. The system was composed of an aqueous droplet supported on a Ag/AgCl disk electrode covered with an organic solution or an organic droplet supported on a Ag/AgTPBCl disk electrode covered with an aqueous solution. In this way, a conventional three-electrode potentiostat can be used to study an ionizable compound transfer process at a liquid/liquid interface with a wide range of phase volume ratios (from 0.0004 to 1 and from 1 to 2500). Using this special cell we designed, only very small volumes of both phase were needed for r equal to unity, which is very useful for the investigation of the distribution of ionizable species at a biphasic system when the available amount of species is limited. The ionic partition diagrams were obtained for different phase volume ratios.

Journal Article↗
PubMed2003

Observation of the marcus inverted region of electron transfer reactions at a liquid/liquid interface.

Scanning electrochemical microscopy was used to probe the influence of a driving force on the heterogeneous electron transfer (ET) processes at the externally polarized water/1,2-dichloroethane interface. Being a part of the driving force, the Galvani potential difference at the interface, Deltaowphi, can be quantitatively controlled in a wide range, allowing the precise measurements of the rate constants of the ET reactions. Two opposite systems were chosen in this work. One was 5,10,15,20-tetraphenyl 21H,23H-porphyrin zinc (ZnPor, O)/Fe(CN)64- (W), and the other was TCNQ (O)/Fe(CN)63- (W). For both systems studied, the relations between the rate constant and the Deltaowphi were of parabolic shape; that is, the rate constants increased initially with the Deltaowphi until reaching a maximum and then decreased steadily as the Deltaowphi increased further. This is in accordance with the prediction of the Marcus theory. To our knowledge, this is the first report that the Marcus inverted region can be observed electrochemically at an unmodified liquid/liquid interface with only one redox couple at each phase. The effect of the concentrations of the organic supporting electrolyte has also been discussed in detail.

Journal Article↗
PubMed2003

Fusion of lamellar body with plasma membrane is driven by the dual action of annexin II tetramer and arachidonic acid.

Annexin II has been implicated in membrane fusion during the exocytosis of lamellar bodies from alveolar epithelial type II cells. Most previous studies were based on the fusion assays by using model membranes. In the present study, we investigated annexin II-mediated membrane fusion by using isolated lamellar bodies and plasma membrane as determined by the relief of octadecyl rhodamine B (R18) self-quenching. Immunodepletion of annexin II from type II cell cytosol reduced its fusion activity. Purified annexin II tetramer (AIIt) induced the fusion of lamellar bodies with the plasma membrane in a dose-dependent manner. This fusion is Ca2+-dependent and is highly specific to AIIt because other annexins (I and II monomer, III, IV, V, and VI) were unable to induce the fusion. Modification of the different functional residues of AIIt by N-ethylmaleimide, nitric oxide, or peroxynitrite abolished AIIt-mediated fusion. Arachidonic acid enhanced AIIt-mediated fusion and reduced its Ca2+ requirement to an intracellularly achievable level. This effect is due to membrane-bound arachidonic acid, not free arachidonic acid. Other fatty acids including linolenic acid, palmitoleic acid, myristoleic acid, stearic acid, palmitic acid, and myristic acid had little effect. AIIt-mediated fusion was suppressed by the removal of arachidonic acid from lamellar body and plasma membrane using bovine serum albumin. The addition of arachidonic acid back to the arachidonic acid-depleted membranes restored its fusion activity. Our results suggest that the fusion between lamellar bodies with the plasma membrane is driven by the synergistic action of AIIt and arachidonic acid.

Animals↗
PubMed2003

[Treatment of erectile dysfunction by implantation of domestic made three-piece inflatable penile prosthesis, a retrospective study of 29 cases].

OBJECTIVE: To evaluate the effect of implantation of domestic made three-piece inflatable penile prosthesis on erectile dysfunction (ED). METHODS: Domestic made three-piece inflatable penile prosthesis were implanted through an incision at the border of penis and scrotum on 29 patients with ED refractory to non-operative treatment, among which 23 being with neurogenic ED, including 18 paraplegia cases and 5 cases of traumatic injury of nervi erigentes; 4 cases with ED caused by arteriovenous fistula; I case with ED caused by fibrosis of corpus cavernosum, and 1 case with ED caused by Klinefelter's syndrome. Follow-up was conducted for 3 - 36 months to survey the clinical effect. RESULTS: Operation was successfully performed upon all 29 patients. Follow-up after operation lasted 3 - 36 months, 18 months on average. Fluid exudation of penile prosthesis and localized infection occurred in 1 patient and mechanic complication occurred in 2 patients. Maintained sexual intercourse rate was 28/29. 3 ED patients with primary arteriovenous fistula made their spouses pregnant after treatment. CONCLUSION: With excellent covertness and at low cost, implantation of domestic made three-piece inflatable penile prosthesis is effective and well accepted by ED patients.

Adult↗
PubMed2003

Effect of nitric oxide on lung surfactant secretion.

Lung surfactant is secreted from epithelial type II cells into alveolar airspace in response to airborne and circulating stimuli. Nitric oxide (NO) can be generated by constitutive and inducible nitric oxide synthases (cNOS and iNOS) in pulmonary endothelial and epithelial cells. The authors therefore examined the effects of NO on lung surfactant secretion using an isolated perfused rat lung model and primary culture of type II cells. Infusion of L-N(G)-nitroarginine methyl ester (L-NAME) (100 micro M), an inhibitor of cNOS and iNOS, via pulmonary circulation for 90 minutes resulted in a decrease of lung surfactant secretion (1.55%+/-0.15% in control versus 0.79%+/-0.16% in L-NAME-treated lungs, P <.05). However, aminoguanide, an inhibitor of iNOS, had no effect, indicating that the decline of lung surfactant secretion is due to the specific blockage of cNOS rather than iNOS activity in perfused lungs. A reduction of cGMP level by 1H-[1,2,4] oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) (25 micro M), a specific inhibitor of guanylyl cyclase, inhibited surfactant secretion by 64%. Furthermore, KT5823 (1 micro M), an inhibitor of protein kinase G, depressed surfactant secretion by 40%. These results suggest that physiological concentrations of NO are required for lung surfactant secretion and NO-mediated secretion is at least partly via a rise of cGMP level and activation of protein kinase G. In primary culture of alveolar type II cells, spermine NONOate (SPER/NO), a NO donor, increased basal phosphatidylcholine (PC) secretion in a dose-dependent manner. Maximal stimulation was observed at 1 micro M. However, in the ATP-stimulated type II cells, SPER/NO displayed a biphasic effect on PC secretion. At low concentrations (0.1 to 1 micro M), SPER/NO increased ATP-stimulated PC secretion, whereas at a high concentration (100 micro M), SPER/NO inhibited the secretion. The results suggest that NO may play an important role in lung surfactant secretion.

Animals↗
PubMed2003

An acoustic-logging transmission-network model (continued): addition and multiplication ALTNs.

On the basis of the acoustic-logging transmission-network (ALTN) model [Fa et al., J. Acoust. Soc. Am. 111(5), 2158-2165 (2002)] this paper puts forward concepts of addition and multiplication ALTNs, proves the reciprocity of two kinds of addition ALTNs, sets up the physical model of the multiplication acoustic array logging tool, calculates their acoustic-beam steering efficiencies, and performs experimental verification.

Journal Article↗
PubMed2003

Serum from rabbit orally administered cobra venom inhibits growth of implanted hepatocellular carcinoma cells in mice.

AIM: To investigate the inhibitory effect of serum preparation from rabbits orally administered cobra venom (SRCV) on implanted hepatocellular carcinoma (HCC) cells in mice. METHODS: An HCC cell line, HepA, was injected into mice to prepare implanted tumors. The animals (n=30) were divided randomly into SRCV, 5-fluorouracil (5-FU), and distilled water (control) groups. From the second day after transplantation, 20 mg/kg 5-FU was administered intraperitoneally once a day for 9 days. SRCV (1,000 mg/kg) or distilled water (0.2 mL) was given by gastrogavage. Tumor growth inhibition was described by the inhibitory rate (IR). Apoptosis was detected by transmission electron microscopy (TEM), flow cytometry (FCM), and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL). Student's t-test was performed for statistical analysis. RESULTS: The tumor growth was inhibited markedly by SRCV treatment compared to that in the control group (P<0.01). The treatment resulted in a significant increase in the apoptotic rate of cancer cells by the factors of 10.5+/-2.4 % and 20.65+/-3.2 % as demonstrated through TUNEL and FCM assays, respectively (P<0.01). The apoptotic cells were also identified by characteristic ultrastructural features. CONCLUSION: SRCV can inhibit the growth of implanted HepA cells in mice, and the apoptosis rate appears to elevate during the process.

Animals↗
PubMed2003

[Proliferating cell nuclear antigen expression in recurrent aphthous ulcer and its significance].

OBJECTIVE: To explore the expression changes of proliferating cell nuclear antigen (PCNA) in oral normal mucosa and recurrent aphthous ulcers(RAU). METHODS: The expression intensity and distribution of PCNA were examined with immunohistochemistry method in 15 cases of recurrent oral aphthous and normal oral mucosa. RESULTS: In RAU, there was large amount of inflamed cells. In normal oral mucosa, the expression intensity of PCNA was significant higher than that in oral aphthous (P<0.05). CONCLUSION: The inhibition of epidermal cells proliferation in RAU may be one of the mechanisms which one involved in RAU formation.

Case-Control Studies↗