Biomedical subjects

Sheng Zhang

Publications and source records attributed to Sheng Zhang.

71 records · Page 4Linked to original sources

PubMed2003

[Effect of bcl-2 antisense oligonucleotides on multidrug resistance of cultured uveal melanoma cells].

OBJECTIVE: To evaluate the chemotherapeutic sensitivity of uveal melanoma in vitro and reverse its drug resistance by the delivery of bcl-2 antisense oligodeoxynucleotide (AS-ODN). METHODS: The drug sensitivity tests of primary cultured uveal melanoma cells toward 5-flurouracil (5-FU), thiophosphamide (TSPA), cisplatin (DDP), adriamycin (ADM), vinblastine (VLB), dacarbazine (DTIC) were performed with 3, -4, 5 dimethyliazol-2,5 diphenyl tetrazolium bromide (MTT). AS-ODN bcl-2 were delivered with cationic lipid to down-regulate bcl-2 expression. Immunohistochemistry and Western-blot methods were used to detect bcl-2 expression. According to the principle of multi-drug mutual action, the influence of anti-apoptosis gene bcl-2 on tumor cell drug sensitivity was measured. RESULTS: Uveal melanoma was resistant to different chemotherapeutic drugs in different degrees. AS-ODN bcl-2 could down-regulate bcl-2 expression, was synergetic with all tested drugs and partially reversed the multi-drug resistance. CONCLUSIONS: Clinically, with ordinary dosages the above 6 drugs have little cytotoxicity to uveal melanoma cells, bcl-2 over-expression is associated with multi-drug resistance and AS-ODN bcl-2 can partially reverse the multi-drug resistance.

Antineoplastic Agents↗

PubMed2003

[Expression and significance of nitric oxide synthase in human hepatocellular carcinoma].

OBJECTIVE: To investigate the expression and significance of nitric oxide synthase (cNOS) mRNA in primary hepatocellular carcinoma (HCC), cirrhotic liver and normal liver tissue. METHODS: cNOS mRNA expression in 80 HCC, 40 cirrhotic liver and 20 normal liver tissue were observed by in situ hybridization. CD34 immunostain was used to measure the microvascular density (MVD) and Ki-67 immunostain to proliferative index. RESULTS: Expression of cNOS mRNA was observed in the liver cancer cells, endothelial cells in the non-cancerous liver tissues and mononuclear and/or phagocytes. Expression of cNOS mRNA in tumor cells of HCC was higher than that in the liver cells of cirrhotic liver (P < 0.01) which was higher than the normal liver tissue. Expression in the endothelial cells was higher in HCC and cirrhotic liver than those in the normal liver tissue (P < 0.01). HCC with positive cNOS mRNA expression in the endothelial cells showed higher extent of neovascularization and degree of proliferative index. The more MVD, the higher proliferative index, which increased in metastatic tumors. CONCLUSION: cNOS mRNA expression was involved in oncogenesis, angiogenesis and progression of hepatocellular carcinoma.

Adolescent↗

PubMed2003

[Expression and significance of transforming growth factor-beta1, matrix metalloproteinase-2 and its inhibitor in lens epithelial cells of diabetic cataract].

OBJECTIVE: To investigate the expression and significance of transforming growth factor-beta(1) (TGF-beta(1)), matrix metalloproteinase-2 (MMP-2) and tissue inhibitor of metalloproteinase-2 (TIMP-2) in human Lens epithelial cells (LEC) of diabetic cataract. METHODS: Immunohistochemical staining was used to detect the expression of TGF-beta(1), MMP-2 and TIMP-2 in the diabetic LEC (23 cases) and the normal LEC (7 cases). RESULTS: There was significant difference of expression of MMP-2 and TGF-beta(1) between diabetic LEC and normal LEC (P < 0.01). But there was no statistic significance for TIMP-2 expression (P > 0.05). There was correlation between the expression of TGF-beta(1) and MMP-2. CONCLUSION: The imbalance induced by TGF-beta(1) between the expression of MMP-2 and TIMP-2 may play a critical role in the pathological fibrosis of anterior and posterior subcapsular during the development of diabetic cataract.

Adult↗

PubMed2003

[Preparation and the characteristic test of magnetic pingyangmycine-bearing microspheres].

OBJECTIVES: To prepare the magnetic pingyangmycine-bearing microspheres (MPMs), test its characteristics, and evaluate the target ability of MPMs. METHODS: MPMs were prepared by a cold-condensation method at first. Then the scan electron microscope, high performance liquid chromatography (HPLC) and atomic absorption spectrometry were used to measure the diameter of MPMs and the contents of PYM and Fe3O4 in MPMs. Drug-releasing instrument was used to test the quantity of PYM released from MPMs. The distribution of intravenously injected MPMs in SD rat liver was investigated under an externally magnetic field. RESULTS: MPMs are spherical with the mean diameter of 32.23 microns. The content of pingyangmycine in MPMs was 3.8% and Fe3O4 was 11.7% (w/w). The quantity of PYM released from MPMs in 3 hours was 63.1%. The content of Fe3O4 in the targeting sites of rats was obviously higher than that in the non-targeting sites (P < 0.01). CONCLUSION: MPMs have good properties of drug-targeting and drug sustain releasing. MPMs may be ideal for the use of the treatment of cavernous hemangioma.

Animals↗

PubMed2003

[Expression of apoptosis and Bcl-2, Bax in hemangioma and vascular malformations].

OBJECTIVE: To study the expression of apoptosis and their regulatory genes, Bcl-2, Bax in hemangioma and vascular malformations. METHODS: The specimens were taken from 68 cases of strawberry hemangioma or vascular malformations and 11 cases of normal skin. The expression of Bcl-2, Bax and Ki-67 in endothelial cells were investigated by immunohistochemical S-P method. The apoptosis index (AI) in endothelial cells was investigated by TUNEL method. RESULTS: Ki-67 was positive in all the proliferating strawberry hemangioma, negative in the other groups. The expression of Bax was significantly higher in strawberry hemangioma than in vascular malformations and normal skin (P < 0.01). Bcl-2 was negative in all groups. The AI in endothelial cells of strawberry hemangioma was significantly higher than that of vascular malformations and normal skin. There were no statistically significant differences between the proliferating and involution strawberry hemangioma. There were no statistically significant differences between various types of vascular malformations and normal skin. With the increasing of the expression of Bax in strawberry hemangioma, the AI increased. CONCLUSION: These findings clearly demonstrate a much higher apoptotic activity in strawberry hemangioma than in vascular malformations and normal skin and suggest that apoptosis might be a cause of spontaneous involution of strawberry hemangioma and might not be a cause of the pathogenesis of vascular malformation. Bcl-2, Bax might play an important regulatory role in apoptosis in endothelial cells of strawberry hemangioma.

Adolescent↗

PubMed2002

Histidine 407, a phantom residue in the E1 subunit of the Escherichia coli pyruvate dehydrogenase complex, activates reductive acetylation of lipoamide on the E2 subunit. An explanation for conservation of active sites between the E1 subunit and transketolase.

Least squares alignment of the E. coli pyruvate dehydrogenase multienzyme complex E1 subunit and yeast transketolase crystal structures indicates a general structural similarity between the two enzymes and provides a plausible location for a short-loop region in the E1 structure that was unobserved due to disorder. The residue H407, located in this region, is shown to be able to penetrate the active site. Suggested by this comparison, the H407A E1 variant was created, and H407 was shown to participate in the reductive acetylation of both an independently expressed lipoyl domain and the intact 1-lipoyl E2 subunit. While the H407A substitution only modestly affected the reaction through pyruvate decarboxylation (ca. 14% activity compared to parental E1), the overall complex has a much impaired activity, at most 0.15% compared to parental E1. Isothermal titration calorimetry measurements show that the binding of the lipoyl domain to the H407A E1 variant is much weaker than that to parental E1. At the same time, mass spectrometric measurements clearly demonstrate much impaired reductive acetylation of the independently expressed lipoyl domain and of the intact 1-lipoyl E2 by the H407A variant compared to the parental E1. A proposal is presented to explain the remarkable conservation of the three-dimensional structure at the active centers of the E. coli E1 subunit and transketolase on the basis of the parallels in the ligation-type reactions carried out and the need to protonate a very weak acid, a dithiolane sulfur atom in the former, and a carbonyl oxygen atom in the latter.

Acetylation↗

PubMed2002

Surface-alkylated polystyrene monolithic columns for peptide analysis in capillary liquid chromatography-electrospray ionization mass spectrometry.

Macroporous poly(styrene-divinylbenzene) (PS-DVB) monoliths were prepared by in situ polymerization in PEEK, fused silica, or stainless steel tubing having an inner diameter of 75 or 125 microm. A process is described for subsequent alkylation of the flow-contacting surfaces of the monoliths. The process treats all the surfaces including through-pore surfaces of the rigid macroporous monolith with a solution containing a dissolved Friedel-Crafts catalyst, an alkyl halide (1-chlorooctadecane), and an organic solvent. This process produces an improved reversed-phase liquid chromatographic separation of peptides compared to an unmodified monolithic PS-DVB column. The surface octadecylation is not necessary for a reversed-phase separation of proteins since both unmodified and modified columns provide comparable results. Tryptic protein digests, standard proteins, and standard peptides were used to evaluate the monolithic columns by employing electrospray mass spectrometry detection. Potential applications in proteomics studies by mass spectrometry, which use the alkylated monolithic column engaged onto the nanofabricated electrospray ionization chip, are also discussed.

Alkylation↗

PubMed2002

Acylation of 2,5-dimethoxycarbonyl[60]fulleropyrrolidine and synthesis of its multifullerene derivatives.

2,5-Dimethoxycarbonyl[60]fulleropyrrolidine (1) is acylated with various chlorocarbonyl compounds to give fullerene derivatives with the general formula C(60)(MeOOCCH)(2)NC(O)R, R = (CH(2))(5)Br, (CH(2))(8)C(O)Cl (3), (CH(2))(4)C(O)Cl, or cis-C(6)H(4)(C(O)Cl. The monoacylated sebacoyl derivative 3 readily reacts with alcohols and amines such as methanol, diethylamine, glycine methyl ester, and aza-18-crown-6 through the remaining chlorocarbonyl group. Chromatography of 3 on silica gel converts it into the corresponding acid C(60)(MeOOCCH)(2)NC(O)(CH(2))(8)COOH (4). Treating 4 with PCl(5) regenerates the precursor 3 quantitatively. Piperazine reacts with 4 in the presence of DCC and BtOH to form a bisfullerene derivative in which two sebacoyl chains and the piperazine act as the bridge between two molecules of 1. Other molecules with multifunctional groups react with 4 similarly to form multifullerene derivatives. NMR data indicate that the rotation of the relatively bulky phthaloyl group is hindered around the amide bond N [bond] C(O), the rotation barrier of which is 15.06 kcal/mol. The relative stereochemistry of the 2,5-dimethoxycarbonyl groups is established by (1)H NMR spectra and further confirmed by resolution of the enantiomeric 2,5-trans-isomer of the starting material 1.

Journal Article↗

PubMed2002

Delta6-, Stearoyl CoA-, and Delta5-desaturase enzymes are expressed in beta-cells and are altered by increases in exogenous PUFA concentrations.

In the evolution of Type II diabetes, an initial period of hyper-fatty acidemia leads to an insulin secretory defect which triggers overt hyperglycemia and frank diabetes. The mechanism by which elevated free fatty acids contribute to beta-cell dysfunction, however, is not clearly understood. We recently reported that arachidonic acid (20:4) or linoleic acid (18:2) supplementations result in increases in abundances of long chain polyunsaturated fatty acids in INS-1 beta-cell membrane lipids, suggesting that beta-cells express desaturases that catalyze generation of unsaturated fatty acids. As expression of desaturases by beta-cells has not yet been addressed, we initiated studies to examine this issue using INS-1 beta-cells and find that they express messages for the Delta6-, stearoyl CoA-, and Delta5-desaturase. Supplementation of the INS-1 beta-cells with arachidonic acid leads to decreased expression of all three desaturases, presumably in response to the decreased need for endogenous generation of unsaturated fatty acids. In contrast, linoleic acid supplementation promoted minimal changes in the three desaturases. These findings demonstrate for the first time that beta-cells express regulatable desaturases. Additionally, reverse transcriptase-polymerase chain reaction analyses reveal expression of the desaturases in native pancreatic islets. It might be speculated that long-term elevations in fatty acids can also adversely influence desaturase activity in beta-cells and affect PUFA composition in beta-cell membranes contributing to beta-cell membrane structural abnormalities and altered secretory function.

Animals↗

PubMed2002

Investigation of ion transfer across the micro-water/nitrobenzene interface facilitated by a fullerene derivative.

A functionalized fullerene derivative containing a monoaza-18-crown-6 moiety was investigated by facilitated ion (such as Li+, Na+, K+, NH4+, Mg2+, and Ca2+) transfer across the micro-water/nitrobenzene interface supported at the tip of a micropipet. The current responses were detected by cyclic voltammetry and Osteryoung square wave voltammetry, which demonstrated that the facilitated ion transfer does occur by an interfacial complexation-dissociation process. The diffusion coefficient of this compound in nitrobenzene was approximately (5.90 +/- 0.04) x 10(-7) cm2 s(-1), which is 1 order of magnitude less than other common ionophores due to the large size of the molecule. The selectivity of this molecule toward the metal ions followed the sequence Na+ > Li+ > K+ > NH4+ > Ca2+ approximately equals Mg2+. In addition, this compound was also easy to form film at the water/nitrobenzene interface to inhibit the simple ion transfer of tetramethylammonium ion. However, the adsorption of this ionophore has less influence on the facilitated metal ion transfer.

Journal Article↗

PubMed2002

Drosophila atrophin homolog functions as a transcriptional corepressor in multiple developmental processes.

Dentatorubral-pallidoluysian atrophy is a progressive neurodegenerative disease caused by the expansion of a polyglutamine repeats within the Atrophin-1 protein. The in vivo function of Atrophin-1 is unknown. We have characterized a Drosophila gene encoding an Atrophin family protein. Analysis of mutant phenotypes indicates that Drosophila Atrophin is required in diverse developmental processes including early embryonic patterning. Drosophila Atrophin genetically interacts with the transcription repressor even-skipped and is required for its repressive function in vivo. Drosophila Atrophin directly binds to Even-skipped in vitro. Furthermore, both human Atrophin-1 and Drosophila Atrophin repress transcription in vivo when tethered to DNA, and poly-Q expansion in Atrophin-1 reduces this repressive activity. We propose that Atrophin proteins function as versatile transcriptional corepressors and discuss a model that deregulation of transcription may contribute to the pathogenesis of neurodegeneration.

Animals↗

PubMed2002

Detection of single nucleotide polymorphisms using electrospray ionization mass spectrometry: validation of a one-well assay and quantitative pooling studies.

Single nucleotide polymorphisms (SNPs) are currently being mapped and databased at a remarkable pace, providing a viable means for understanding disease susceptibility, differential drug response and human evolution. Consequently, there is an increasing demand for SNP genotyping technologies that are simple, rapid, cost effective and readily amenable to automation for high-throughput analyses. In this study, we improved the Survivor Assay, a SNP detection method based on electrospray ionization mass spectrometry (ESI-MS), with several developments. One improvement is the development of a one-well assay, requiring no off-line purification of the polymerase chain reaction product, achieved by simple addition of reagent solution into a single well. Another is the on-line separation of magnesium and dideoxynucleotides using an in-house made monolithic metal chelating column, eliminating any off-line sample preparation prior to mass spectrometric analysis. Here the Survivor Assay is extended from a proof-of-principle concept to a validated method by genotyping six SNPs from five different regions of human genomic DNA in 55 individual samples with 100% accuracy. This improved Survivor Assay eliminates the tedious and time-consuming steps of sample preparation, minimizes sample handing and offers a high-throughput analysis of SNPs by ESI-MS. The current combined preparation and analysis time is 2 min per sample. The simplicity of this method has potential for full automation and parallel chromatography and, thus, reduced analysis time. In addition, we have adapted the Survivor Assay for quantitative SNP analysis in pooled DNA samples. The capabilities and sensitivity of this approach were evaluated. We demonstrate that an allele occurring at a frequency of 2% can consistently be quantitated.

Alleles↗

PubMed2002

Stimulation of insulin secretion and associated nuclear accumulation of iPLA(2)beta in INS-1 insulinoma cells.

Accumulating evidence suggests that the cytosolic calcium-independent phospholipase A(2) (iPLA(2)beta) manifests a signaling role in insulin-secreting (INS-1) beta-cells. Earlier, we reported that insulin-secretory responses to cAMP-elevating agents are amplified in iPLA(2)beta-overexpressing INS-1 cells (Ma Z, Ramanadham S, Bohrer A, Wohltmann M, Zhang S, and Turk J. J Biol Chem 276: 13198-13208, 2001). Here, immunofluorescence, immunoaffinity, and enzymatic activity analyses are used to examine distribution of iPLA(2)beta in stimulated INS-1 cells in greater detail. Overexpression of iPLA(2)beta in INS-1 cells leads to increased accumulation of iPLA(2)beta in the nuclear fraction. Increasing glucose concentrations alone results in modest increases in insulin secretion, relative to parental cells, and in nuclear accumulation of the iPLA(2)beta protein. In contrast, cAMP-elevating agents induce robust increases in insulin secretion and in time-dependent nuclear accumulation of iPLA(2)beta fluorescence, which is reflected by increases in nuclear iPLA(2)beta protein content and specific enzymatic activity. The stimulated effects are significantly attenuated in the presence of cell-permeable inhibitors of protein phosphorylation and glycosylation. These findings suggest that conditions that amplify insulin secretion promote translocation of beta-cell iPLA(2)beta to the nuclei, where it may serve a crucial signaling role.

1-Methyl-3-isobutylxanthine↗

PubMed2002

[An experimental study of inhibition of tetrandrine on posterior capsular opacification in rabbits].

OBJECTIVE: To study the effect of tetrandrine (Tet) on the formation of posterior capsular opacification (PCO) after cataract extraction. METHODS: Intraocular lens implantation was performed on 48 healthy rabbit eyes, and they were randomly divided into 4 groups: control (A), dexamethasone (B), Tet (C) and Tet with coated IOL (D). Dexamethasone and Tet were postoperatively injected into the subconjunctival space. The number of cells, the contents of protein and malondialdehyde (MDA) in the aqueous were determined at different days postoperatively. The PCO was scored and opaque posterior capsules were weighted. RESULTS: The number of cells, the amount of protein in aqueous, the scales and the wet weight of PCO in the treated eyes were less than that of the control eyes (P < 0.05). In B and C group, except the 14th day content, the postoperative MDA was lower than that in the control group (P < 0.05). CONCLUSION: Tet can inhibit the formation of PCO, and has no obvious toxicity to the corneal endothelium.

Alkaloids↗

PubMed2002

[Relationship of expression unbalance of matrix metalloproteinase and tissue inhibitor of metalloproteinase to invasiveness and metastasis in gastric carcinomas].

BACKGROUND & OBJECTIVE: Matrix metalloproteinase-9 (MMPs) and its tissue inhibitor of metalloproteinase-1 (TIMPs) have the important regulatory roles in the processes during tumor invasion and metastasis. Observing the coexpression of matrix metalloproteinase 9(MMP-9) and tissue inhibitor of metalloproteinase 1(TIMP-1) in gastric carcinomas, this study was designed to investigate the relationship of the expression unbalance of MMP-9 and TIMP-1 to the invasiveness, metastasis, and prognosis in gastric carcinomas. METHODS: By using immunohistochemistry, the expression of MMP-9, TIMP-1, and proliferating cell nuclear antigen Ki-67 was detected in 256 gastric cancers, and the patients were followed-up. RESULTS: The expressive degree of MMP-9 in the tumor invasion beyond musculariis propria(70.13%) was higher than that within lamina propria or submucosa(42.50%, P < 0.05) and its expression in tumor was positively associated with tumor cell proliferation index and lymph node metastasis, and its expression in high TNM stage(75.00%) was higher than those in low TNM stage(46.15%, P < 0.05). The relation of the expression of TIMP-1 to the depth of invasion, lymph node metastasis, and TNM stage was negative(Pearson contingency coefficient were 0.1688, 0.3556, and 0.3004, respectively P < 0.05). There were four groups of the unbalance expression of MMP-9 and TIMP-1 in gastric carcinomas. While the frequency of the serosa invasion and lymph node metastasis in the group of the expression of MMP-9 over TIMP-1 was significantly higher than those in the groups of the expression of TIMP-1 over MMP-9 or the balance expression of MMP-9 and TIMP-1. However, prognosis of the patients with the expression of MMP-9 over TIMP-1 was significantly worse than that with expression of TIMP-1 over MMP-9(P < 0.05). CONCLUSION: The expression of MMP-9 was positively related to the tumor invasiveness and metastasis in gastric cancers, however the association between the positive expression of TIMP-1 and the invasiveness and metastasis was negative. The relationship of MMP-9 and TIMP-1 to the invasiveness and metastasis in gastric carcinomas was that MMP-9 promotes and TIMP-1 inhibits tumor metastasis. The patients with MMP-9 positive expression and TIMP-1 negative expression are poorer prognosis.

Adult↗

PubMed2002

[Research on the relationship between pathological features of the uveal melanoma and prognosis].

OBJECTIVE: To study the pathological features of uveal melanoma and to evaluate their influence on patients' prognosis. METHODS: Paraffin embedded uveal melanoma tissues of 115 cases were examined using routine pathologic methods. Three histological types were classified according to the modified Callender system and patients were followed clinically. The data were done regression and survival analysis by SPSS statistic soft. RESULTS: The patient with epithelial cell type, mixed type, and spindle cell type uveal melanoma have different life times, the average life time is 35.6 +/- 21.5 months, 63.7 +/- 37.0 months, 69.5 +/- 36.5 months in turn, patients with epithelial uveal melanoma had shorter survival time than other two types. The survival time was negatively related to the largest diameter of contact area with the sclera, the largest height and the depth of tumor invasion to the sclera. CONCLUSIONS: Epithelial uveal melanoma is more malignant than the other two types. Histological classification of this tumor combined with other pathologic features can indicate the patient's prognosis.

Eye Neoplasms↗

PubMed2002

[Determination of imperatorin in tetraploidy radix Angelicae dahuricae].

OBJECTIVE: To determine the content of imperatorin in the tetraploidy radix angelicae dahuricae, and compare it with the original diplontic varites. METHOD: The chromatographic method was carried out on Nova-pak (4.6 mm x 200 mm, 5 microns) column with acetonitrile-water solution as a mobile phase. The flow rate was 1 ml.min-1. the detection wavelength was at 248 nm, and the column temperature was 25 degrees C. RESULT: The eontent of was imperatorin in the tetraploidy radix 0.460% and 0.225% imperatorin in the diplontic species. CONCLUSION: The content of the mainly active constituent in the tetraploid is double to what it is in the original diplontic species.

Angelica↗