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Biomedical subjects

Peng Sun

Publications and source records attributed to Peng Sun.

46 records · Page 3Linked to original sources
PubMed2003

[Treatment of the paraplegic patient with erectile dysfunction by implantation of China-made three-piece inflatable penile prosthesis].

OBJECTIVE: To evaluate the effect of the treatment on paraplegic patients with erectile dysfunction (ED) by implantation of China-made three-piece inflatable penile prosthesis. METHODS: Eighteen paraplegic patients with ED refractory to non-operative treatment were implanted with three-piece inflatable penile prosthesis through an incision at the border of penis and scrotum. The rate of maintained coitus and the satisfactory coitus of spouse were obtained by inquiring and letter visiting. RESULTS: Operations were successfully performed upon all 18 patients. Follow-ups after operations ranged from 3 months to 36 months, mean follow-up being 18 months. Fluid exudation from penile prosthesis and localized infection occurred in one patient and mechanic complication occurred in two. Maintained coitus rate was 17/18. Ejaculation reflection occurred in three patients. CONCLUSIONS: Treatment of paraplegic patient with ED refractory to non-operative treatment by implantation of China-made three-piece inflatable penile prosthesis has good concealment and rehabilitative effect, with similar mechanical troubles to imported products. With excellent covertness, implantation of three-piece inflatable penile prosthesis is well accepted by ED patients.

Adult↗
PubMed2003

Nimesulide inhibits tumor growth in mice implanted hepatoma: overexpression of Bax over Bcl-2.

AIM: To investigate whether nimesulide could suppress tumor growth and induce apoptosis in implanted hepatoma mice and to explore the molecular mechanisms. METHODS: Male mice received nimesulide 10 mg/kg, 20 mg/kg, and 40 mg/kg ig daily for 21 d. Electron microscopy (EM), flow cytometry (FCM), DNA ladder, radioimmunoassay (RIA), and Western blot analysis were employed to investigate effect of nimesulide on mice hepatoma and the related molecular mechanisms. RESULTS: Nimesulide inhibited the growth of hepatoma (from 14 % to 62 %) and elicited typical apoptotic morphologic changes. The DNA ladder of high dose nimesulide was more clearly observed and apoptotic rate was 51.3 %+/-1.5 %. Nimesulide also decreased cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2) and Bcl-2 expression, while increased the level of Bax protein. CONCLUSION: Nimesulide suppresses tumor growth and induces apoptosis by inhibiting COX-2 and PGE2 expression, which may be related to overexpression of Bax over Bcl-2.

Animals↗
PubMed2003

[Characteristics of epidermal growth factor and its receptor expression in dermal chronic ulcers].

OBJECTIVE: To investigate the expression and location of epidermal growth factor (EGF) and its receptor (EGFR) in dermal chronic ulcers and normal skin in order to explore their influence on ulcer formation. METHODS: The expression intensity and distribution of EGF and EGFR were detected with pathological method and immunohistochemistry method in 8 cases of dermal ulcers, 8 cases of edge of ulcer and 8 cases of normal skin. RESULTS: The Positive signals of EGF could be found in epidermal cells, endothelial cells and some fibroblasts; EGFR was principally located in the cytoplasm and cellular membrane of these cells mentioned above in normal skin. From normal skin, edge of ulcer to ulcerative tissues, the protein contents of EGF and EGFR were decreased progressively. In ulcerative tissues, EGF was mostly distributed in monocytes and macrophages while EGFR was chiefly sited in monocytes. When compared with normal skins, the protein expression of EGF and EGFR was notably reduced in ulcerative tissues (both P<0.01). The positive cellular ratios of two proteins were reduced to (7.1+/-5.2) % and (8.8+/-5.5) % of those in normal skin respectively (all P<0.01). CONCLUSION: The formation of dermal chronic ulcers is closely associated with the reduction of EGF and EGFR protein expression which may lead to binding obstruction between EGF and its receptor.

Adult↗
PubMed2002

Small GTPase Rah/Rab34 is associated with membrane ruffles and macropinosomes and promotes macropinosome formation.

Macropinocytosis is an efficient process for the uptake of nutrients and solute macromolecules into cells from the external environment. Macropinosomes, which are surrounded by actin, are formed from the cell surface membrane ruffles and migrate toward the cell center. We have cloned the entire coding sequence of a member of the Rab family small GTPases, Rah/Rab34. It lacked a consensus sequence for GTP-binding/GTPase domain. Although wild-type Rah exhibited extremely low GTPase activity in vitro, it exerted appreciable GTPase activity in vivo. In fibroblasts, Rah was colocalized with actin to the membrane ruffles and membranes of relatively large vesicles adjacent to the ruffles. These vesicles were identified as macropinosomes on the basis of several criteria. Rah and Rab5 coexisted in some, but not all, macropinosomes. Rah was predominantly associated with nascent macropinosomes, whereas Rab5 was present in endosomes at later stages. The number of macropinosomes in the cells overexpressing Rah increased about 2-fold. The formation of macropinosomes by the treatment of platelet-derived growth factor or phorbol ester was also facilitated by Rah but suppressed by a dominant-negative Rah. Rah-promoted macropinosome formation was retarded by dominant-negative mutants of Rac1 and WAVE2, which are essential for membrane ruffling. These results imply that Rah is required for efficient macropinosome formation from the membrane ruffles.

Amino Acid Sequence↗
PubMed2002

Involvement of actin cytoskeleton in modulation of Ca(2+)-activated K(+) channels from rat hippocampal CA1 pyramidal neurons.

Using inside-out configuration of patch clamp techniques, actin cytoskeleton modulation of large conductance calcium-activated potassium (BK(Ca)) channels was studied in hippocampal CA1 pyramidal neurons from adult rat. Disruption of actin filament after brief treatment with cytochalasin D (CD) markedly decreased activity of BK(Ca) channels and this inhibitory action persisted even after CD washout. This CD-produced decrease in BK(Ca) channel activity was characterized by a shortened open lifetime and reduced opening frequency. Disruption of actin filament with another toxin cytochalasin B also exerted similar effects as CD. Phalloidin, the actin filament stabilizer, had no significant effect on BK(Ca) channel activity, while pre-treatment with phalloidin could prevent the CD-induced inhibitory effect on channel activity. The present study demonstrates that disruption of actin cytoskeleton can inhibit BK(Ca) channel activity, suggesting that BK(Ca) channels in rat hippocampal CA1 pyramidal neurons may be directly modulated by dynamic assembly and disassembly of submembranous actin cytoskeleton.

Actins↗
PubMed2002

Study of electron transfer across the liquid/ice-like matrix interface by scanning electrochemical microscopy.

In this work, we report the findings of a study on scanning electrochemical microscopy (SECM) to investigate the interfacial electron-transfer (ET) reaction between the 7,7,8,8-tetracyanoquinodimethane radical anion (TCNQ*-) in 1,2-dichloroethane and ferricyanide in an ice-like matrix (a mixture of insulting ice and conductive liquid) under low temperatures. Experimental results indicate that the formed liquid/ice-like matrix interface is superficially similar in electrochemical characteristics to a liquid/liquid interface at temperatures above -20 degrees C. Furthermore, imaging data show that the surface of the ice-like matrix is microscopically flat and physically stable and can be applied as either a conductive or an insulting substrate for SECM studies. Perchlorate ion was selected as the common ion in both phases, the concentrations of which controlled the interfacial potential difference. The effect of perchlorate concentration in the DCE phase on interfacial reactions has been studied in detail. The apparent heterogeneous rate constants for TCNQ*- oxidation by Fe(CN)6(3-) in another phase under different temperatures have been calculated by a best-fit analysis, where the experimental approach curves are compared with the theoretically derived relationships. Reaction rate data obey Butler-Volmer formulation before and after the freezing point, which is similar to most other known cases of ET reactions at liquid/liquid interfaces. However, there is a sharp change observed for heterogeneous rate constants around the freezing point of the aqueous phase, which reflects the phase transition. At temperatures below -20 degrees C, surface-confined voltammograms for the reduction of ferricyanide were obtained, and the ice-like matrix became an insulating one, which indicates that the aqueous phase is really a frozen phase.

Journal Article↗
PubMed2002

Nitration of annexin II tetramer.

Annexin II tetramer (AII(t)) is a member of the Ca(2+)- and phospholipid-binding protein family and is implicated in membrane fusion during surfactant secretion. It had previously been shown that high concentrations of nitric oxide (NO) inhibit surfactant secretion from lung type II cells. NO reacts with superoxide (O(2)(-)) to form peroxynitrite (ONOO(-)), a tyrosine nitrating agent, which is found in lungs under certain pathological conditions. It is therefore hypothesized that nitration of AII(t) by ONOO(-) may be a mechanism for the NO inhibition of regulated exocytosis. We therefore performed in vitro studies to test effects of ONOO(-) on AII(t). Western blot analysis using anti-nitrotyrosine antibodies showed a dose-dependent nitration of tyrosine residues in AII(t) treated with ONOO(-). Nitration occurred on the core domain of the p36 subunit, as well as on the p11 subunit. ONOO(-) also caused the formation of dimers between p36 and p11 subunits which were stable in the presence of heating, SDS, and beta-mercaptoethanol. AII(t)-mediated liposome aggregation was inhibited by ONOO(-) with an IC(50) of approximately 30 microM. The inhibition was abolished by urate (a scavenger of ONOO(-) and *OH), but not by mannitol (a scavenger of *OH) or superoxide dismutase (a scavenger of O(2)(-)) and appeared to be specific to AII(t), since ONOO(-) only slightly influenced annexin I-mediated liposome aggregation. The conformational change of AII(t) induced by Ca(2+) had no effect on the inhibition. Furthermore, ONOO(-) only partially inhibited the binding of AII(t) to membranes. Nitration of AII(t) also occurred in intact A549 cells, a lung epithelial cell line, treated with ONOO(-). The results of this study suggest that AII(t)-mediated liposome aggregation was inhibited by nitration of the protein.

Animals↗
PubMed2002

Inactivation of annexin II tetramer by S-nitrosoglutathione.

We investigated the effect of nitric oxide (NO) donors on the activities of annexin II tetramer (AIIt), a member of the Ca2+- dependent phospholipid-binding protein family. Incubation of purified AIIt with S-nitrosoglutathione (GSNO) led to the inhibition of AIIt-mediated liposome aggregation. This effect was dose-dependent with an IC50 of approximately 100 micro m. Sodium nitroprusside, another NO donor also inhibited AIIt-mediated liposome aggregation, whereas reduced glutathione, nitrate, or nitrite had no effects. GSNO also inhibited AIIt-mediated membrane fusion, but not the binding of AIIt to the membrane. GSNO only has a modest effect on liposome aggregation mediated by annexins I, III or IV. The binding of AIIt to the membrane protected the reactive sites of GSNO on AIIt. GSNO did not inhibit AIIt-mediated liposome aggregation in the presence of dithiothreitol. Taken together, our results suggest that GSNO inactivates AIIt possibly via S-nitrosylation and/or the formation of disulfide bonds.

Animals↗
PubMedDate not supplied

Two new bioactive triterpene glycosides from the sea cucumber Pseudocolochirus violaceus.

By activity-guided fractionation, two new triterpene glycosides, violaceusides A (1) and B (2), were isolated from the sea cucumber Pseudocolochirus violaceus as active compounds causing morphological abnormality of Pyricularia oryzae mycelia. By extensive 2D NMR techniques and chemical evidence, the structures of the two new glycosides were established as 16beta-acetoxy-3-O-[3-O-methyl-beta-D-glucopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 4)-beta-D-quinovopyranosyl-(1 --> 2)-4-O-sodiumsulphate-beta-D-xylopyranosyl]-holosta-7,24-diene-3beta-ol (1) and 16beta-acetoxy-3-O-[3-O-methyl-beta-D-glucopyranosyl-(1 --> 3)-beta-D-xylopyranosyl-(1 --> 4)-beta-D-glucopyranosyl-(1 --> 2)-4-O-sodiumsulphate-beta-D-xylopyranosyl]-holosta-7,24-diene-3beta-ol (2), respectively. The two glycosides also exhibited significant cytotoxicity against HL-60 and BEL-7402 cancer cell lines.

Animals↗