Biomedical subjects

Dong Shen

Publications and source records attributed to Dong Shen.

16 recordsLinked to original sources

PubMed2006

Enhanced solubilization of bovine serum albumin in reverse micelles by compressed CO2.

The effect of compressed CO2 on the solubilization of bovine serum albumin (BSA) in water/sodium bis-(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles was studied by observing phase behavior and recording UV-visible spectra under different conditions. The pH values within the water cores of reverse micelles at different CO2 pressures were also determined. The solubilization capacity of the reverse micelles for the protein increased considerably as CO2 pressure increased within the low-pressure range, but decreased at higher CO2 pressures, so that the micelles eventually lost their ability to solubilize the protein. The effect of CO2 on the stability of the reverse micelles played an important role in the relationship between pressure and protein solubility. A "multicomplex" model was proposed to explain these effects. The different solublization capacities within different pressure ranges demonstrates the unique advantage of using compressed CO2 in the extraction of proteins with reverse micelles.

Carbon Dioxide↗

PubMed2006

Augmentation of revascularization and prevention of plasma leakage by angiopoietin-1 and vascular endothelial growth factor co-transfection in rats with experimental limb ischaemia.

BACKGROUND: Angiopoietin-I (Ang I) and vascular endothelial growth factor (VEGF) are endothelial cell-specific growth factors. In the current study, we tested the hypothesis that co-expression of AngI and VEGF could have an effect on development of leakage-resistant vessels. METHODS AND RESULTS: Expression plasmids, pcD2 (control plasmid), pcD2/AngI, pcD2NEGF121, or pcD2/AngI +pcD2NEGF121, were injected intramuscularly into an ischaemic hindlimb rat model, followed by electroporation. Collateral vessel development and skeletal muscle atrophy were assessed before and 7, 14, 28 days after treatment. Capillary density was significantly increased in the rats transfected with AngI or VEGF compared with that in the rats transfected with pcD2 alone (P < 0.05). Rats transfected with AngI + VEGF had the highest capillary density (P < 0.05). The mean perimeter ratio of ligated hindlimb to non-ligated hindlimb was lower with pcD2 treatment rats compared with that in the rats transfected with AngI, VEGF or AngI +VEGF (P < 0.01). Limb necrosis was observed in two of 33 control rats, but none in the AngI and/orVEGF gene-transferred rats. The amount of extravasated Evans blue in rat ligated hindlimb muscle (7 days after treatment) treated with both AngI and VEGF was significantly less compared with that in the rats transfected with VEGF alone (P < 0.01). CONCLUSIONS: The current study demonstrated that co-expression of AngI and VEGF genes in the ischaemic muscle effectively develops leakage-resistant vessels in the rat model. Therefore, this approach may provide a more appropriate therapeutic strategy in ischaemic vascular diseases.

Angiopoietin-1↗

PubMed2005

Detection and quantification of mutations in the plasma of patients with colorectal tumors.

The early detection of cancers through analysis of circulating DNA could have a substantial impact on morbidity and mortality. To achieve this goal, it is essential to determine the number of mutant molecules present in the circulation of cancer patients and to develop methods that are sufficiently sensitive to detect these mutations. Using a modified version of a recently developed assay for this purpose, we found that patients with advanced colorectal cancers consistently contained mutant adenomatous polyposis coli (APC) DNA molecules in their plasma. The median number of APC DNA fragments in such patients was 47,800 per ml of plasma, of which 8% were mutant. Mutant APC molecules were also detected in >60% of patients with early, presumably curable colorectal cancers, at levels ranging from 0.01% to 1.7% of the total APC molecules. These results have implications for the mechanisms through which tumor DNA is released into the circulation and for diagnostic tests based on this phenomenon.

Adult↗

PubMed2005

Phase behaviors of AOT/longer chain n-alkanes reverse micelles in the presence of compressed ethylene.

It was found that, in a suitable pressure range, ethylene could increase the amount of solubilized water in reverse micelles of sodium bis-2-ethylhexylsulfosuccinate (AOT) in longer chain n-alkanes considerably, where the phase separation was induced by a micelle-micelle interaction mechanism. The microenvironments in the ethylene-stabilized reverse micelles were investigated by the UV-vis adsorption spectra using methyl orange (MO) as a probe. The maximum absorption of MO decreased with the increase of ethylene pressure at constant W0 value. Conductivity measurements demonstrated that the percolation temperature of the reverse micellar system increased considerably after compressed ethylene was added. The results of this work confirm that some small-molecule gases have the function of cosurfactants to stabilize reverse micelles.

Journal Article↗

PubMed2005

Preparation and characterization of inclusion complexes of beta-cyclodextrin with ionic liquid.

The solubilities of beta-cyclodextrin (beta-CD), ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), and their mixture in water were determined, and the conductivity of these aqueous solutions was measured. It was demonstrated that beta-CD and bmimPF6 could enhance the solubility of each other, and the solubility curves of each were linear with gradients of about 1. The conductivity decreased remarkably with increasing beta-CD concentration, and a discernible break in the conductivity curve could be observed when beta-CD and bmimPF6 were equimolar in the solution. The solubility and conductivity results indicated that inclusion complexes (ICs) of 1:1 stoichiometry were formed. The inclusion compounds were further characterized by using powder X-ray diffraction (XRD) analysis, 13C CP/MAS (cross-polarization magic-angle spinning) NMR and 1H NMR spectroscopy, and thermogravimetric analysis (TGA). The results showed that the ICs were a fine crystalline powder. The host-guest system exhibited a channel-type structure and each glucose unit of beta-CD was in a similar environment. The decomposition temperature of the ICs was lower than that of bmimPF6 and beta-CD individually.

Journal Article↗

PubMed2005

TX-100/water/1-butyl-3-methylimidazolium hexafluorophosphate microemulsions.

Both ionic liquids and water are typical green solvents. In this work, the phase behavior of the ternary system consisting of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), TX-100, and water was determined at 25.0 degrees C. The water-in-bmimPF6, bicontinuous, and bmimPF6-in-water microregions of the microemulsions were identified by cyclic voltammetry method using potassium ferrocyanide K4Fe(CN)6 as the electroactive probe. Dynamic light scattering (DLS) and the UV-vis method were used to characterize the microemulsions. It was demonstrated that the hydrodynamic diameter (Dh) of the bmimPF6-in-water microemulsions is nearly independent of the water content but increases with increasing bmimPF6 content due to the swelling of the micelles by the ionic liquid. The UV-vis further confirmed the existence of water domains in the water-in-bmimPF6 microemulsions, and the salt potassium ferricyanide K3Fe(CN)6 could be dissolved in the water domains.

Journal Article↗

PubMed2005

Solvatochromic behavior of phenol blue in CO2+ethanol and CO2+n-pentane mixtures in the critical region and local composition enhancement.

The UV-Vis spectra of probe phenol blue in CO(2)+ethanol and CO(2)+n-pentane binary mixtures were studied at 308.15 K and different pressures. The experiments were conducted in both supercritical region and subcritical region of the mixtures by changing the compositions of the mixed solvents. On the basis of the experimental results the local compositions of the solvents about phenol blue were estimated by neglecting the size difference of CO(2) and the cosolvents. Then the local composition data were corrected by a method proposed in this work, which is mainly based on Lennard-Jones sphere model. It was demonstrated that the local mole fraction of the cosolvents is higher than that in the bulk solution at all the experimental conditions. In the near critical region of the mixed solvents the local composition enhancement, defined as the ratio of cosolvent mole fraction about the solute to that in the bulk solution, increased significantly as pressure approached the phase boundary from high pressure. The local composition enhancement was not considerable as pressure was much higher than the critical pressure. In addition, in subcritical region the degree of composition enhancement was much smaller and was not sensitive to pressure in the entire pressure range as the concentration of the cosolvents in the mixed solvents was much higher than the concentration at the critical point of the mixtures.

Journal Article↗

PubMed2005

Compressed CO2 in AOT reverse micellar solution: effect on stability, percolation, and size.

The effects of compressed CO(2) in sodium bis-2-ethylhexylsulfosuccinate (AOT)/decane reversed micellar solution on the stability of the micelles, interface, and micelle/micelle interactions were studied. It was demonstrated that the compressed gas could increase the solubilization of water in this system. The formation of the stabilized one-phase microemulsion was confirmed by conductivity measurements. A shift in percolation threshold to higher temperature was observed after compressed gas was added. The gyration radius (R(g)) of the reverse micelles was determined using SAXS. R(g) increases with the addition of water, while it decreases appreciably with increasing pressure of compressed gas at fixed W(0). These results were interpreted in terms of an increase of the rigidity of the interface layer and a decrease of the interdroplet attraction. The results of this work provide useful information to get insight into the mechanism of cosurfactants to stabilize reverse micelles.

Journal Article↗

PubMed2005

Enhanced stabilization of reverse micelles by compressed CO2.

The effect of compressed CO2 on the solubilization capacity of water in reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in longer chain n-alkanes was studied at different temperatures and pressures. It was found that the amount of solubilized water is increased considerably by CO2 in a suitable pressure range. The suitable CO2 pressure range in which the solubilization capacity of water could be enhanced decreased with increasing W0 (water-to-AOT molar ratio). The microenvironments in the CO2-stabilized reverse micelles were investigated by UV/Vis adsorption spectroscopy with methyl orange (MO) as probe. The mechanism by which the reverse micelles are stabilized by CO2 is discussed in detail. The main reason is likely to be that CO2 has a much smaller molecular volume than the n-alkane solvents studied in this work. Therefore, it can penetrate the interfacial film of the reverse micelles and stabilize them by increasing the rigidity of the micellar interface and thus reducing the attractive interaction between the droplets. However, if the CO2 pressure is too high, the solvent strength of the solvents is reduced markedly, and this induces phase separation in the micellar solution.

Journal Article↗

PubMed2004

Enhancement of the solubilization capacity of water in Triton X-100/cyclohexane/water system by compressed gases.

The effect of compressed CO2 and ethylene on the properties of Triton X-100/cyclohexane/water systems was studied at different temperatures and pressures. Surprisingly, it was discovered that the compressed gases had the functions of co-surfactants. At suitable pressures, the water-to-surfactant molar ratio (W0) was enhanced significantly by the dissolution of the gas in the solution. The microenvironment in the reverse micelles was investigated by UV-visible spectroscopy by using methyl orange (MO) as a probe. The influence of n-hexane, Na2CO3, NaHCO3, H2C2O4, and CaCl2 at various concentrations on the solubilization of water in the absence of compressed gases was also investigated in order to obtain some information about the mechanism of the interesting phenomenon. This new route to stabilize reverse micelles may have potential applications to other similar systems. Moreover, the results of this work provide some useful information to get insight into the mechanism of co-surfactants, because a conventional co-surfactant usually contains both polar group and hydrocarbon chain, and it is very difficult to clarify the functions these two groups, while the gases used in this work are small nonpolar molecules, which solely have the function of the hydrocarbon chain in a co-surfactant.

Journal Article↗

PubMed2004

Mutational analysis of the tyrosine phosphatome in colorectal cancers.

Tyrosine phosphorylation, regulated by protein tyrosine phosphatases (PTPs) and kinases (PTKs), is important in signaling pathways underlying tumorigenesis. A mutational analysis of the tyrosine phosphatase gene superfamily in human cancers identified 83 somatic mutations in six PTPs (PTPRF, PTPRG, PTPRT, PTPN3, PTPN13, PTPN14), affecting 26% of colorectal cancers and a smaller fraction of lung, breast, and gastric cancers. Fifteen mutations were nonsense, frameshift, or splice-site alterations predicted to result in truncated proteins lacking phosphatase activity. Five missense mutations in the most commonly altered PTP (PTPRT) were biochemically examined and found to reduce phosphatase activity. Expression of wild-type but not a mutant PTPRT in human cancer cells inhibited cell growth. These observations suggest that the mutated tyrosine phosphatases are tumor suppressor genes, regulating cellular pathways that may be amenable to therapeutic intervention.

Catalytic Domain↗

PubMed2004

Three classes of genes mutated in colorectal cancers with chromosomal instability.

Although most colorectal cancers are chromosomally unstable, the basis for this instability has not been defined. To determine whether genes shown to cause chromosomal instability in model systems were mutated in colorectal cancers, we identified their human homologues and determined their sequence in a panel of colorectal cancers. We found 19 somatic mutations in five genes representing three distinct instability pathways. Seven mutations were found in MRE11, whose product is involved in double-strand break repair. Four mutations were found among hZw10, hZwilch/FLJ10036, and hRod/KNTC, whose products bind to one another in a complex that localizes to kinetochores and controls chromosome segregation. Eight mutations were found in Ding, a previously uncharacterized gene with sequence similarity to the Saccharomyces cerevisiae Pds1, whose product is essential for proper chromosome disjunction. This analysis buttresses the evidence that chromosomal instability has a genetic basis and provides clues to the mechanistic basis of instability in cancers.

Animals↗

PubMed2004

Functional defects in the fanconi anemia pathway in pancreatic cancer cells.

Biallelic BRCA2-mutations can cause Fanconi anemia and are found in approximately 7% of pancreatic cancers. Recently, several sequence changes in FANCC and FANCG were reported in pancreatic cancer. Functional defects in the Fanconi pathway can result in a marked hypersensitivity to interstrand crosslinking agents, such as mitomycin C. The functional implications of mutations in the Fanconi pathway in cancer have not been fully studied yet; these studies are needed to pave the way for clinical trials of treatment with crosslinking agents of Fanconi-defective cancers. The competence of the proximal Fanconi pathway was screened in 21 pancreatic cancer cell lines by an assay of Fancd2 monoubiquitination using a Fancd2 immunoblot. The pancreatic cancer cell lines Hs766T and PL11 were defective in Fancd2 monoubiquitination. In PL11, this defect led to the identification of a large homozygous deletion in FANCC, the first cancer cell line found to be FANCC-null. The Fanconi-defective cell lines Hs766T, PL11, and CAPAN1 were hypersensitive to the crosslinking agent mitomycin C and some to cis-platin, as measured by cell survival assays and G(2)/M cell-cycle arrest. These results support the practical exploration of crosslinking agents for non-Fanconi anemia patients that have tumors defective in the Fanconi pathway.

Cell Cycle Proteins↗

PubMed2004

[Postoperative intraperitioneal hyperthermic chemoperfusion combined with intravenous chemotherapy for 82 advanced gastric cancer patients].

OBJECTIVE: To evaluate the efficacy of postoperative intraperitoneal hyperthermic chemoperfusion (IHCP) combined with intravenous chemotherapy for advanced gastric cancer. METHODS: Eighty-two patients with stage II - IV gastric cancer were postoperatively randomized into two groups; 46 patients in treatment group who received IHCP combined with intravenous chemotherapy for three times and 36 patients in control group who received intravenous chemotherapy only for six times. All patients in the two groups received the same chemo-regimen LFAP (CF + 5-Fu + THP or MIT + PDD) 21 - 28 days after operation. RESULTS: The 1-year survival rate was 98% (45/46) in the treatment group and 94% (34/36) in the control group without any significant difference (P > 0.05). The 3-year survival rate was 83% (38/46) in the treatment group and 61% (22/36) in the control group with significant difference (P < 0.05). Gastrointestinal reaction in the treatment group was significantly decreased compared with in the control group (37% vs 80%, P < 0.01), whereas no statistically significant difference was noted in bone marrow suppression (P > 0.05). CONCLUSION: Intraperitoneal hyperthermic chemoperfusion combined with intravenous chemotherapy can prolong survival and reduce gastrointestinal side-effect which provides an effective treatment option for advanced gastric cancer.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2003

Gene expression and antitumor effect following im electroporation delivery of human interferon alpha 2 gene.

AIM: To investigate the gene expression and antitumor effect following im electroporation delivery of human interferon alpha 2 (hIFN-alpha 2) gene. METHODS: The pcD2/hIFN-alpha 2 was injected into the middle of the quadriceps muscle of female BALB/c mice or the leukemia-bearing female BALB/c nude mice, and then electroporation was given to the injection site. Optimal electrical parameters and the efficiency of gene transfer was studied with hIFN-alpha 2 ELISA kit. The HL-60 tumor model in BALB/c nude mice was used to investigate therapeutic effects of im electroporation delivery of pcD2/hIFN-alpha 2. RESULTS: The optimal conditions for the electric pulses were as follows: voltage at 200 V/cm; pulse duration at 40 ms per pulse; number of pulse at 6 pulses and frequency at 1 Hz. Under optimal conditions, the serum hIFN-alpha 2 levels in electroporation group (160 microg/L+/-31 microg/L) were 45-fold higher than those of nonelectroporation group (3.6 microg/L+/-1.6 microg/L, P<0.01). The growth of leukemia was inhibited more obviously and the survival time of the leukemia-bearing nude mice was prolonged after im electroporation delivery of pcD2/hIFN-alpha 2 100 microg or 200 microg. CONCLUSION: Electroporation was an efficient method for the delivery of plasmid DNA and im electroporation delivery of pcD2/hIFN-alpha 2 was effective in treating leukemia.

Animals↗

PubMed2003

Clinical observation in 86 cases of acne vulgaris treated with Compound Oldenlandis Mixture.

86 cases of acne vulgaris were treated with Fu Fang She She Cao He Ji ([symbol: see text] Compound Oldenlandis Mixture), with the other 34 cases treated with Dang Gui Ku Shen Wan ([symbol: see text] Pills Prepared from Chinese Angelica and Flavescent Sophora Root) as the controls, to observe the therapeutic effect of the former. The results showed that the cure plus markedly effective rate was 73.26% in the treatment group, and 47.06% in the control group, with a significant difference in the cure plus markedly effective rate between the two groups (P < 0.01), and also in the total effective rate between the two groups significant (P < 0.05). It may be concluded that the Compound Oldenlandis Mixture is a better agent for the illness.

Acne Vulgaris↗