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Biomedical subjects

Ping Wang

Publications and source records attributed to Ping Wang.

At least 109 records · Page 6Linked to original sources
PubMed2006

[Inhibition of gastric cancer cells growth in vitro by sulindac].

OBJECTIVE: To investigate the effect of sulindac on proliferation and apoptosis of human gastric cancer BGC-823 cells and its antineoplastic mechanisms. METHODS: Human gastric cancer BGC-823 cells were incubated with sulindac at various concentrations and for different times. Morphological changes of BGC-823 cells were observed under an inversion microscope. MTT colorimetric assay was used to examine the effect of sulindac on the proliferation of BGC-823 cells. Flow cytometry was used to determine the cell cycle distribution and apoptosis. Transmission electron microscopy was performed to examine cell apoptosis morphology. Immunohistochemical staining was used to detect the expressions of COX-2, bcl-2 and ki-67 in the cells. RESULTS: sulindac induced morphologic alterations in BGC-823 cells, inhibited cell proliferation, increased the proportion of cells in G0/G1 phase and decreased the proportion of cells in S phase, induced apoptosis of BGC-823 cells, and decreased expressions of COX-2, bcl-2, ki-67 in the cells. All the effects were in a time- and dose-dependent manner (P < 0.05). Some characteristic morphologic features of apoptosis were revealed by transmission electron microscopy. CONCLUSION: sulindac may inhibit the growth of gastric cancer BGC-823 cells in vitro and the anti-tumor mechanism may be related to changes in cell cycle distribution, induction of apoptosis and inhibition of expression of COX-2, bcl-2, and ki-67.

Antineoplastic Agents↗
PubMed2006

[The expression of HIF-1 in the early diabetic NOD mice].

PURPOSE: To study the retinal expression of HIF-1 alpha in the diabetic NOD mice. METHODS: NOD mice were divided into normal control group and diabetes group randomly, sacrificed at 2, 4, 6, 8 or 12 weeks. Eyes were enucleated and retinas were isolated and used for western blot, or eyes were sectioned for immunohistochemical staining for HIF-1 alphal. RESULTS: Compared to the normal control group, blood sugar of diabetes mice increased significantly but the weights decreased significantly (P < 0.01). Western blot of retinal lysates showed low levels of HIF-1 alpha at the 6th weeks that were markedly increased at the 12th weeks in the diabetes group. Immunohistochemistry showed increased staining for HIF-1 in the inner retina, but not in the outer retina. CONCLUSION: The retinal HIF-1 alpha levels increasing showed that retinal ischemia happening in the early diabetes. HIF-1 alpha may participate in the secondary damage of retinal ischemia induced by early diabetes.

Animals↗
PubMed2006

[Expression of BDNF and trk B in the cochleas of the aged rats].

OBJECTIVE: To explore the correlation between the expression of brain derived neurotrophic factor (BDNF) and presbycusis in the cochleae of the aged rats. METHOD: The mRNA expression of BDNF and presbycusis in the cochleas of the aged rats was quantitated by real time PCR. RESULT: The expression of BDNF in the cochleas of the aged rats with presbycusis was obviously less than that in the control group. And the difference was statistically significant. CONCLUSION: The expression of BDNF is closely correlated to presbycusis in the aged rats.

Aging↗
PubMed2006

[Fourier transform infrared spectroscopy study on normal and malignant tissues of cervix].

Fourier transform infrared spectroscopy (FTIR) was used to investigate 35 cervical tissues , including 17 squamous cell carcinoma of cervical samples, and 5 adenocarcinoma of cervical samples, 13 normal cervical samples. The results show that there are 18 spectral bands with highly appearance percentage(>80%) in these three types of tissues, and these spectral bands may be the characteristic infrared spectra bands for cervical tissues; Some of relative absorbance ratios are statistically significant (p < 0.05) among these three types of tissues. These differences of relative absorbance ratios are mainly centered at 1080, 1238, 1314, 1339, 1397, 1454, 1541, 1647, 2854, 2873, 2926, and 2958 cm(-1). The present results indicate that FTIR can be used to distinguish these three types of tissues. The utilization of FTIR spectra in cervical tissues is expected to be a hopeful method in cervical cancer screening and clinical diagnosis in the future.

Adult↗
PubMed2005

[Screening and preliminary identification of mimetic peptides of Plasmodium falciparum-infected erythrocyte membrane surface protein 1].

OBJECTIVE: To screen and identify mimetic peptides of Plasmodium falciparun-infected erythrocyte membrane surface protein 1 in order to explore anti-adhesive agent against cerebral malaria. METHODS: Phage-borne peptide KLYLIAEGSVAA was used as panning targets to select target binders in a disulfide-constrained heptapeptides library. Three rounds of biopanning were carried out and then ELISA and competitive ELISA were used to evaluate the binding character between phage-borne peptides and ICAM-1. The insert DNA sequences of positive clones were determined and their amino acid sequences were deduced. RESULTS: After three-round panning, 22 clones were randomly chosen from the third panning and analyzed. Three clones showed positive interaction with ICAM-1, and two of them possessed the amino acid sequence C-ITAVPVR-C, the other one was C-DIMGGYN-C. These peptides specifically inhibited the binding of 15.2 antibody to ICAM-1 detected by competitive ELISA. CONCLUSION: Two kinds of mimetic peptides of PfEMP-1 have been obtained, which can bind with ICAM-1 specifically.

Amino Acid Sequence↗
PubMed2005

Biological studies of photoinducible phenol quaternary ammonium derivatives.

Three water-soluble DNA cross-linking phenol quaternary ammonium derivatives 3, 4, and 5 could inhibit the transcription in vitro by photoactivation. DNA interstrand cross-linking action might be the key factor to inhibit transcription by these compounds. Further tumor cell apoptosis was observed by flow cytometry it indicated that cross-linking agent 5 could significantly induce the late apoptosis of tumor cells.

Apoptosis↗
PubMed2005

Increases in oxygen consumption without cerebral blood volume change during visual stimulation under hypotension condition.

The magnitude of the blood oxygenation level-dependent (BOLD) signal depends on cerebral blood flow (CBF), cerebral blood volume (CBV) and cerebral metabolic rate of oxygen (CMRO2). Thus, it is difficult to separate CMRO2 changes from CBF and CBV changes. To detect the BOLD signal changes induced only by CMRO2 responses without significant evoked CBF and CBV changes, BOLD and CBV functional magnetic resonance imaging (fMRI) responses to visual stimulation were measured under normal and hypotension conditions in isoflurane-anesthetized cats at 4.7 T. When the mean arterial blood pressure (MABP) decreased from 89+/-10 to 50+/-1 mm Hg (mean+/-standard deviation, n=5) by infusion of vasodilator sodium nitroprusside, baseline CBV in the visual cortex increased by 28.4%+/-8.3%. The neural activity-evoked CBV increase in the visual cortex was 10.8%+/-3.9% at normal MABP, but was negligible at hypotension. Positive BOLD changes of +1.8%+/-0.5% (gradient echo time=25 ms) at normal MABP condition became prolonged negative changes of -1.2%+/-0.3% at hypotension. The negative BOLD response at hypotension starts approximately 1 sec earlier than positive BOLD response, but similar to CBV change at normal MABP condition. Our finding shows that the negative BOLD signals in an absence of CBV changes are indicative of an increase in CMRO2. The vasodilator-induced hypotension model simplifies the physiological source of the BOLD fMRI signals, providing an insight into spatial and temporal CMRO2 changes.

Animals↗
PubMed2005

Effects of SWNT and metallic catalyst on hydrogen absorption/desorption performance of MgH2.

The microstructure and absorption/desorption characteristics of composite MgH2 and 5 wt % as-prepared single-walled carbon nanotubes (MgH2-5ap) obtained by the mechanical grinding method were investigated. Experimental results show that the MgH2-5ap sample exhibits faster absorption kinetics and relatively lower desorption temperature than pure MgH2 or MgH2-purified single-walled carbon nanotube composite. Storage capacities of 6.0 and 4.2 wt % hydrogen for the MgH2-5ap composite were achieved in 60 min at 423 and 373 K, respectively. Furthermore, its desorption temperature was reduced by 70 K due to the introduction of as-prepared single-walled carbon nanotubes (SWNTs). In addition, the different effects of SWNTs and metallic catalysts contained in the as-prepared SWNTs were also investigated and a hydrogenation mechanism was proposed. It is suggested that metallic particles may be mainly responsible for the improvement of the hydrogen absorption kinetics, and SWNTs for the enhancement of hydrogen absorption capacity of MgH2.

Journal Article↗
PubMed2005

Alkylpurine-DNA-N-glycosylase excision of 7-(hydroxymethyl)-1,N6-ethenoadenine, a glycidaldehyde-derived DNA adduct.

Glycidaldehyde (GDA) is a bifunctional alkylating agent that has been shown to be mutagenic in vitro and carcinogenic in rodents. However, the molecular mechanism by which it exerts these effects is not established. GDA is capable of forming exocyclic hydroxymethyl-substituted etheno adducts on base residues in vitro. One of them, 7-(hydroxymethyl)-1,N6-ethenoadenine (7-hm-epsilonA), was identified as the principal adduct in mouse skin treated with GDA or a glycidyl ether. In this work, using defined oligonucleotides containing a site-specific 7-hm-epsilonA, the human and mouse alkylpurine-DNA-N-glycosylases (APNGs), responsible for the removal of the analogous 1,N6-ethenoadenine (epsilonA) adduct, are shown to recognize and excise 7-hm-epsilonA. Such an activity can be significantly modulated by both 5' neighboring and opposite sequence contexts. The efficiency of human or mouse APNG for excision of 7-hm-epsilonA is about half that, or similar to the excision of epsilonA, respectively. When human or mouse cell-free extracts were tested, however, the extent of 7-hm-epsilonA excision is dramatically lower than that for epsilonA, suggesting that, in the crude extracts, the APNG activities toward these two adducts are differentially affected. Using cell-free extracts from APNG deficient mice, this enzyme is shown to be the primary glycosylase excising 7-hm-epsilonA. A structural approach, using molecular modeling, was employed to examine how the structure of the 7-hm-epsilonA adduct affects DNA conformation, as compared to the epsilonA adduct. These novel substrate specificities could have both biological and structural implications.

Adenine↗
PubMed2005

Expression in blood cells may contribute to biochemical and pathological improvements after neonatal intravenous gene therapy for mucopolysaccharidosis VII in dogs.

Mucopolysaccharidosis VII (MPS VII) is a lysosomal storage disease due to deficient activity of beta-glucuronidase (GUSB) that results in accumulation of glycosaminoglycans in many organs. We have previously reported that neonatal intravenous injection of a gamma retroviral vector (RV) expressing canine GUSB resulted in transduction of hepatocytes, high levels of GUSB modified with mannose 6-phosphate in blood, and reduction in disease manifestations in the heart, bone, and eye. However, it was unclear if liver was the only site of expression, and the effect upon other organs was not assessed. We demonstrate here that blood cells from these RV-treated MPS VII dogs had substantial copies of RV DNA, and expressed the RNA at 2% of the level found in liver. Therefore, expression of GUSB in blood cells may synergize with uptake of GUSB from blood to reduce storage in organs. The RV-treated dogs had marked biochemical and pathological evidence of reduction in storage in liver, thymus, spleen, small intestines, and lung, and partial reduction of storage in kidney tubules. The brain had 6% of normal GUSB activity, and biochemical and pathological evidence of reduction in storage in neurons and other cell types. Thus, this neonatal gene therapy approach is effective and might be used in humans if it proves to be safe. Both secretion of enzyme into blood by hepatocytes, and expression in blood cells that migrate into organs, may contribute to correction of disease.

Animals↗
PubMed2005

Exploration of the nature of active Ti species in metallic Ti-doped NaAlH4.

Clarification of the nature of active Ti species has been a key challenge in developing Ti-doped NaAlH(4) as a potential hydrogen storage medium. Previously, it has been greatly hindered by the invisibility of Ti-containing species in conventional analysis techniques. In the present study, for the first time, the catalytically active Ti-containing species have been definitely identified by X-ray diffraction in the hydrides doped with metallic Ti. It was found that mechanical milling of a NaH/Al mixture or NaAlH(4) with metallic Ti powder resulted in the formation of nanocrystalline Ti hydrides. The variation of the preparation conditions during the doping process leads to a slight composition variation of the Ti hydrides. The catalytic enhancement arising upon doping the hydride with commercial TiH(2) was quite similar to that achieved in the hydrides doped with metallic Ti. Moreover, the cycling stability that was previously established in metallic Ti-doped hydrides was also observed in the hydrides doped with TiH(2). These results clearly demonstrate that the in situ formed Ti hydrides act as active species to catalyze the reversible dehydrogenation of NaAlH(4). The mechanism by which Ti hydrides catalyze the reversible de-/hydrogenation reactions of NaAlH(4) was discussed.

Journal Article↗
PubMed2005

[Effect of endothelin-1 and its antagonists on the expression of endothelin receptors mRNA in HSC-T6 cells].

OBJECTIVE: To study the effect of endothelin-1 (ET-1) and its antagonists on the expression of endothelin and its receptors mRNA in HSC-T6 cells. METHODS: Cultured HSC-T6 cells were randomly divided into 7 groups: Sham control group, ET-1 group (10 nmol/L ET-1), BQ-123 group [1 micromol/L BQ-123, a selective endothelin receptor A (ETRA) antagonist], BQ-788 group [1 micromol/L BQ-788, a selective endothelin receptor B (ETRB) antagonist], ET-1 + BQ123 group (10 nmol/L ET-1 + 1 micromol/L BQ-123), ET-1 + BQ-788 group (10 nmol/L ET-1 + 1 micromol/L BQ-788) and ET-1 + BQ-788 group (10 nmol/L ET-1 + 1 micromol/L BQ-123 + 1 micromol/L BQ-788). The expression of endothelin receptor mRNA of HSC-T6 cells was determined by reverse-transcription polymerase chain reaction (RT-PCR). RESULTS: The expression of ETRA mRNA in ET-1 + BQ123 + BQ788 and ET-1 + BQ788 group was significantly lower than ET-1 group (0.329 +/- 0.044 and 0.292 +/- 0.023 vs. 0.440 +/- 0.030 P < 0.05). Compared with ET-1 group, the expression of ETRB mRNA in ET-1 + BQ788 group was down regulated obviously (0.499 +/- 0.136 vs. 0.153 +/- 0.071, P < 0.05). There was no significant difference in ET-1 + BQ123 group and ET-1 + BQ123 + BQ788 group when compared with ET-1 group (0.499 +/- 0.136 vs. 0.496 +/- 0.103 and 0.299 +/- 0.129, P > 0.05). CONCLUSIONS: ET-1 has no obvious effect on the expression of ETRA mRNA in HSC-T6. ET-1 may up-regulate the expression of ETRB mRNA. Act on ETRA receptor, ET-1 can inhibit the expression of ETRB mRNA.

Animals↗
PubMed2005

Gene expression profiling in INS-1 cells overexpressing thioredoxin-interacting protein.

Thioredoxin-interacting protein (TXNIP) is overexpressed in diabetes and has deleterious effects on pancreatic beta-cells and the cardiovascular system. TXNIP is a regulator of the cellular redox state, but has also been suggested to act as a transcriptional repressor. However, the genes and pathways regulated by TXNIP remain unknown. We therefore compared gene expression in INS-1 insulinoma beta-cells overexpressing TXNIP and control LacZ-overexpressing cells using the Affymetrix 230A rat chip. Analysis with the Bayes methodology revealed 98 differentially expressed genes, 90 of which were down-regulated, consistent with the predicted role of TXNIP as a repressor. Using the PathwayAssist software, we found that affected genes were involved in cell death/survival and insulin secretion, and confirmed these findings by real-time RT-PCR and by functional studies. Thus, aside from regulating the cellular redox, TXNIP does modulate overall gene transcription and thereby may further enhance beta-cell death and impair insulin secretion.

Carrier Proteins↗
PubMed2005

Total synthesis of CRM646-A and -B, two fungal glucuronides with potent heparinase inhibition activities.

[reaction: see text] CRM646-A (1) and -B (2), two fungal glucuronides with a dimeric 2,4-dihydroxy-6-alkylbenzoic acid (orcinol p-depside) aglycone showing significant heparinase and telomerase inhibition activities, were synthesized for the first time. The successful approach involved construction of the phenol glucuronidic linkage, via coupling of the orsellinate derivative 27 with glucuronate bromide 7, before assembly of the phenolic ester linkage in the depside aglycone. Attempts via direct glycosylation of the depside aglycone derivatives were not successful.

Acremonium↗