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Ling Zhang

Publications and source records attributed to Ling Zhang.

At least 73 records · Page 4Linked to original sources
PubMed2006

[The inhibitory effect of Hydrilla verticillata culture water on Microcystic aeruginosa and its mechanism].

This paper studied on the effect and mechanism that the growth of M. aerugonsa was markedly inhibited by the H. verticillata culture water. During treatment, the photosynthetic rate of M. aerugonsa declined, while its respiratory rate and SOD activity increased firstly, then decreased as the treatment went on. Its membrane permeability also increased significantly. TEM photographs showed that the ultrastructure of cell membrane, thylakoid lamella and pith nucleoid of M. aerugonsa were destroyed severely. Inhibitory effects could be observed only when the extracts were extracted by ether. The more extracts from ether, the better inhibitory effect observed. It suggested that the inhibitory effects of H. verticillata on M. aeruginosa were through excreting substances into water. GC/MS analytic result showed that the ether extract mainly consisted of 1,2-benzenedicarboxylic acid diisooctyl ester, dibutyl phthalate, and 1,2-benzenedicarboxylic acid butyl 2-methylpropyl ester.

Culture Media, Conditioned↗
PubMed2005

Application of a rank-based genetic association test to age-at-onset data from the Collaborative Study on the Genetics of Alcoholism study.

Association studies of quantitative traits have often relied on methods in which a normal distribution of the trait is assumed. However, quantitative phenotypes from complex human diseases are often censored, highly skewed, or contaminated with outlying values. We recently developed a rank-based association method that takes into account censoring and makes no distributional assumptions about the trait. In this study, we applied our new method to age-at-onset data on ALDX1 and ALDX2. Both traits are highly skewed (skewness > 1.9) and often censored. We performed a whole genome association study of age at onset of the ALDX1 trait using Illumina single-nucleotide polymorphisms. Only slightly more than 5% of markers were significant. However, we identified two regions on chromosomes 14 and 15, which each have at least four significant markers clustering together. These two regions may harbor genes that regulate age at onset of ALDX1 and ALDX2. Future fine mapping of these two regions with densely spaced markers is warranted.

Adult↗
PubMed2005

Synthesis of Ag-Fe3O4 heterodimeric nanoparticles.

We report a general synthetic method for construction of size-controlled Ag-Fe3O4 heterodimeric nanoparticles using the Fe3O4 nanoparticles as the seeds. The Ag-Fe3O4 heterodimeric nanoparticle can be controlled by tuning the size of the Fe3O4 seed and reaction conditions for synthesis of the Ag nanoparticles grown on it. The as-synthesized nanoparticles can be readily converted into aqueous-soluble form with newly introduced functional groups on the surface of Ag-Fe3O4 heterodimeric nanoparticles.

Dimerization↗
PubMed2005

[Proteomic analysis of prostate cancer using surface enhanced laser desorption/ionization mass spectrometry].

OBJECTIVE: To identify the serum biomarkers of prostate cancer by using protein chip and bioinformatics. METHODS: Eighty three prostate cancer (PCA) patients and ninety five healthy people from mass screen in Changchun were detected by surface-enhanced laser desorption/ionization mass spectrometry (SELDI-MS). The data of spectra were analyzed by bioinformatics tools-Biomarker Wizard and Biomarker Pattern. RESULTS: Compared with the spectra of healthy people, there were 18 potential markers detected in the spectra of the PCA patients, the protein expression was high in 4 of which and low in the 10 of which. The softwares Biomarkerwizard and Biomarker Pattern automatically, under given conditions, selected 8 biomarker proteins to be used to establish a five layer decision tree differentiate to diagnose PCA and differentiate PCA from healthy people with a specificity of 92.632% and a sensitivity of 96.386%. CONCLUSION: New serum biomarkers of PCA have been identified, and this SELDI mass spectrometry coupled with decision tree classification algorithm will provide a highly accurate and innovative approach for the early diagnosis of PCA.

Aged↗
PubMed2005

Concanavalin A-captured glycoproteins in healthy human urine.

Both the urinary proteome and its glycoproteome can reflect human health status, and more directly, functions of kidney and urinary tracts. Because the high abundance protein albumin is not N-glycosylated, the urine N-glycoprotein enrichment procedure could deplete it, and urine proteome could thus provide a more detailed protein profile in addition to glycosylation information especially when albuminuria occurs in some kidney diseases. In terms of describing the details of urinary proteins, the urine glycoproteome is even a better choice than the proteome itself. Pooled urine samples from healthy volunteers were collected and acetone-precipitated for proteins. N-Linked glycoproteins enriched with concanavalin A affinity purification were separated and analyzed by SDS-PAGE-reverse phase LC/MS/MS or two-dimensional LC/MS/MS. A total of 225 urinary proteins were identified based on two-hit criteria with reliability over 97% for each peptide. Among these proteins, 94 were identified in previous urine proteome works, 150 were annotated as glycoproteins in Swiss-Prot, and 43 were predicted as glycoproteins by NetNGlyc 1.0. A number of known biomarkers and disease-related glycoproteins were identified. Because changes in protein quantity or the glycosylation status can lead to changes in the concanavalin A-captured glycoprotein profile, specific urine glycoproteome patterns might be observed for specific pathological conditions as multiplex urinary biomarkers. Knowledge of the urine glycoproteome is important in understanding kidney and body function.

Concanavalin A↗
PubMed2005

The effect of inhibition of Ca2+-independent phospholipase A2 on chemotherapeutic-induced death and phospholipid profiles in renal cells.

We demonstrate that cells derived from primary cultures of rabbit proximal tubules (RPTC), human embryonic kidney (HEK293) and human kidney carcinomas (Caki-1) express microsomal Ca(2+)-independent phospholipase A(2) (iPLA(2)gamma) and cytosolic Ca(2+)-independent phospholipase A(2) (iPLA(2)beta). Inhibition of iPLA(2) activity in these cells using the iPLA(2) inhibitor bromoenol lactone (BEL) (0-5.0microM) for 24h did not induce cell death as determined by annexin V and propidium iodide (PI) staining. However, BEL treatment prior to cisplatin (50muM) or vincristine (2microM) exposure reduced apoptosis 30-50% in all cells tested (RPTC, HEK293 and Caki-1 cells). To identify the phospholipids altered during cell death electrospray ionization-mass spectrometry and lipidomic analysis of HEK293 and Caki-1 cells was performed. Cisplatin treatment reduced 14:0-16:0 and 16:0-16:0 phosphatidylcholine (PtdCho) 50% and 35%, respectively, in both cell lines, 16:0-18:2 PtdCho in Caki-1 cells and increased 16:1-22:6 plasmenylcholine (PlsCho). BEL treatment prior to cisplatin exposure further decreased 14:0-16:0 PtdCho, 16:0-16:1 PlsCho and 16:0-18:1 PlsCho in HEK293 cells, and inhibited cisplatin-induced increases in 16:1-22:6 PlsCho in Caki-1 cells. Treatment of cells with BEL prior to cisplatin exposure also increased the levels of several arachidonic containing phospholipids including 16:0-20:4, 18:1-20:4, and 18:0-20:4 PtdCho, compared to cisplatin only treated cells. These data demonstrate that inhibition of iPLA(2) protects against chemotherapeutic-induced cell death in multiple human renal cell models, identifies specific phospholipids whose levels are altered during cell death, and demonstrates that alterations in these phospholipids correlate to the protection against cell death in the presence of iPLA(2) inhibitors.

Animals↗
PubMed2005

Down-regulation of signal transducer and activator of transcription 3 expression using vector-based small interfering RNAs suppresses growth of human prostate tumor in vivo.

PURPOSE: Signal transducer and activator of transcription 3 (Stat3) is constitutively activated in a variety of cancers and it is a common feature of prostate cancer. Thus, Stat3 represents a promising molecular target for tumor therapy. We applied a DNA vector-based Stat3-specific RNA interference approach to block Stat3 signaling and to evaluate the biological consequences of Stat3 down-modulation on tumor growth using a mouse model. EXPERIMENTAL DESIGN: To investigate the therapeutic potential of blocking Stat3 in cancer cells, three small interfering RNAs (siRNA; Stat3-1, Stat3-2, and Stat3-3) specific for different target sites on Stat3 mRNA were designed and used with a DNA vector-based RNA interference approach expressing short hairpin RNAs to knockdown Stat3 expression in human prostate cancer cells in vitro as well as in vivo. RESULTS: Of the three equivalently expressed siRNAs, only Stat3-3 and Stat3-2, which target the region coding for the SH2 domain and the coiled-coil domain, respectively, strongly suppressed the expression of Stat3 in PC3 and LNCaP cells. The Stat3-1 siRNA, which targeted the DNA-binding domain, exerted no effect on Stat3 expression, indicating that the gene silencing efficiency of siRNA may be dependent on the local structure of Stat3 mRNA. The Stat3 siRNAs down-regulated the expression of Bcl-2 (an anti-apoptotic protein), and cyclin D1 and c-Myc (cell growth activators) in prostate cancer cells. Inhibition of Stat3 and its related genes was accompanied by growth suppression and induction of apoptosis in cancer cells in vitro and in tumors implanted in nude mice. CONCLUSIONS: These data indicate that Stat3 signaling is a promising molecular target for prostate cancer therapy and that vector-based Stat3 siRNA may be useful as a therapeutic agent for treatment of prostate cancer.

Animals↗
PubMed2005

Monoclonal side population progenitors isolated from human fetal pancreas.

The side population (SP) phenotype might represent a common molecular feature for a wide variety of stem cells. The aim of this study was to investigate whether monoclonal SP progenitor cells were established from human fetal pancreas. Islet-like cell clusters (ICCs) were isolated from human fetal pancreas. Monolayer epithelium-like cells were obtained from the ICCs and passaged thereafter. Single SP or non-SP cells were sorted from these cells at the sixth passage. The rate of clone formation was about 2.7% for the SP cells, whereas there was no clone formation for the non-SP cells. The SP cell clones were further expanded for more than 15 passages and induced for differentiation into cells with characteristics of pancreatic beta-cells. We show for the first time that the monoclonal SP progenitors are established from human fetal pancreas. Therefore, this study may offer a novel method to purify pancreatic progenitor cells from human tissues.

Cell Culture Techniques↗
PubMed2005

Cyclooxygenase 2 inhibition promotes IFN-gamma-dependent enhancement of antitumor responses.

In previous studies, we demonstrated an immune suppressive network in non-small cell lung cancer that is due to overexpression of tumor cyclooxygenase 2 (COX-2). In this study, we assessed the vaccination response to tumor challenge following either pharmacological or genetic inhibition of COX-2 in a murine lung cancer model. Treatment of naive mice with the COX-2 inhibitor, SC-58236, skewed splenocytes toward a type 1 cytokine response, inducing IFN-gamma, IL-12, and IFN-gamma-inducible protein 10, whereas the type 2 cytokines IL-4, IL-5, and IL-10 remained unaltered. Fifty percent of mice receiving SC-58236 and an irradiated tumor cell vaccine completely rejected tumors upon challenge. Those mice that did form tumors following challenge demonstrated a reduced tumor growth. In contrast, all mice either vaccinated with irradiated tumor cells alone or receiving SC-58236 alone showed progressive tumor growth. Studies performed in CD4 and CD8 knockout mice revealed a requirement for the CD4 T lymphocyte subset for the complete rejection of tumors. To determine the role of host COX-2 expression on the vaccination responses, studies were performed in COX-2 gene knockout mice. Compared with control littermates, COX-2(-/-) mice showed a significant tumor growth reduction, whereas heterozygous COX-2(-/+) mice had an intermediate tumor growth reduction following vaccination. In vivo depletion of IFN-gamma abrogated the COX-2 inhibitor-mediated enhancement of the vaccination effect. These findings provide a strong rationale for additional evaluation of the capacity of COX-2 inhibitors to enhance vaccination responses against cancer.

Adjuvants, Immunologic↗
PubMed2005

Revealing the role of glutathione S-transferase omega in age-at-onset of Alzheimer and Parkinson diseases.

We previously reported a linkage region on chromosome 10q for age-at-onset (AAO) of Alzheimer (AD) and Parkinson (PD) diseases. Glutathione S-transferase, omega-1 (GSTO1) and the adjacent gene GSTO2, located in this linkage region, were then reported to associate with AAO of AD and PD. To examine whether GSTO1 and GSTO2 (hereafter referred to as GSTO1h) are responsible for the linkage evidence, we identified 39 families in AD that lead to our previous linkage and association findings. The evidence of linkage and association was markedly diminished after removing these 39 families from the analyses, thus providing support that GSTO1h drives the original linkage results. The maximum average AAO delayed by GSTO1h SNP 7-1 (rs4825, A nucleotide) was 6.8 (+/-4.41) years for AD and 8.6(+/-5.71) for PD, respectively. This is comparable to the magnitude of AAO difference by APOE-4 in these same AD and PD families. These findings suggest the presence of genetic heterogeneity for GSTO1h's effect on AAO, and support GSTO1h's role in modifying AAO in these two disorders.

Age of Onset↗
PubMed2005

[Effect of shikonin, a phytocompound from Lithospermum erythrorhizon, on rat vascular smooth muscle cells proliferation and apoptosis in vitro].

OBJECTIVE: To study the anti-proliferation, pro-apoptosis and cell cycle blocking effects of shikonin on rat vascular smooth muscle cell (VSMC) in vitro. METHODS: VSMCs were primarily cultured by explant method from the thoracic aorta of male SD rats. Shikonin of different concentration, 4, 2, 1, 0.5, 0.25, and 0 micromol/L was added. The cell viability was detected by MTT method. Cell growth curve was drawn by trypan blue exclusion method. (3)H-thymidine incorporation was used to calculate the inhibition rate of DNA synthesis. Flow cytometry was used to detect the cell cycle. Cell apoptosis was observed by fluorescence microscopy. Western blotting was performed to detect the expression of different cell apoptosis and cell cycle regulatory proteins, such as cyclin D(1) and E, proliferating cell nuclear antigen (PCNA), p21(waf1/cip1), p27(kip1), and p53. RESULTS: Compared with control group, shikonin had no obvious cytotoxic effect on cell viability at the concentration of 0.25-1 micromol/L (P > 0.05). While it could inhibit, both time- and dose-dependently, the growth of VSMC, which was predominant of 1 micromol/L at 72 h (1.9 x 10(5)/well vs 5.8 x 10(5)/well, P < 0.05), and DNA synthesis was also significantly inhibited in a time- and dose-dependent manner with inhibition rate varied from 33 to 98% (P < 0.05 or P < 0.01). 1 micromol/L shikonin significantly blocked the cell cycle progression in proliferative VSMC, decreased S, G(2)/M phase (P < 0.05) and increased G(0)/G(1) phase (P < 0.05) to quiescent level with sub-G(1) apoptotic distribution at 48 h (10.9% +/- 0.3%). Shikohin at the concentration of 1-2 micromol/L significantly increased the percentage of apoptotic cells in a time- and dose-dependent manner compared with control group (2.8%-23.7% vs 0.2%-0.4%, P < 0.05), and typical apoptotic nuclear morphological changes were observed. 1 micromol/L shikonin significantly down-regulated cyclin D(1), E and PCNA expression, up-regulated p21(wif1/cip1) expression, and did not obviously influence the p27(kip1) and p53 expression. CONCLUSION: Shikonin inhibits the proliferation, promotes the apoptosis and blocks cell cycle progression of VSMC. These effects are associated with the expression changes of cell cycle regulatory proteins.

Animals↗
PubMed2005

Amino acid residues associated with enzymatic activities of the isomerizing phycoviolobilin-lyase PecE/F.

PecE and PecF jointly catalyze the covalent attachment of phycocyanobilin to Cys-alpha84 of PecA and its concomitant isomerization to phycoviolobilin. (a) An Eschertchia coli supernatant expressing pecF has a residual activity of 6%; compared to the holoenzyme, this activity is lost upon purification. (b) Functional domains of both subunits from the cyanobacterium Mastigocladus laminosus were evaluated by mutageneses and chemical modification of amino acids. When in PecE the two motifs Y29YAAWWL and D263DLL were deleted, the holoenzyme lost its activity; it is also inactivated upon deletion of a central part (R111 to A122). The three conserved cysteines C48, C91, and C161 have only minor effects on catalysis. When in PecF the 20 C-terminal and 56 N-terminal amino acids were truncated, the lyase-isomerase activity in combination with PecE decreased to 12% and 15%, respectively, compared to the native enzyme. The catalytic efficiency (k(cat)/K(m)) decreased 16-fold when the unique four histidine residues in PecF beginning at H53 were deleted. H121 and C122 of PecF are essential for the enzyme activity; they are part of a unique stretch extending from A104 to N125 which is absent in the beta-subunit of related but nonisomerizing lyases. A single histidine and a single tryptophan are required for activity in both PecE and PecF, as judged from diethyl pyrocarbonate and N-bromosuccinimide modification and statistical analyses. Inactivation of PecE and PecF is also possible by arginine-specific reagents, while modifications of lysine, glutamate, and aspartate retained activity. (c) PecE and PecF, as well as most of the mutants, bind PCB covalently in substoichiometric amounts, as assayed by Zn(2+)-induced fluorescence on denaturing gels.

Amino Acid Sequence↗
PubMed2005

Perturbation of nanoscale structure of polypeptide multilayer thin films.

Multilayer thin films formed by sequential deposition of oppositely charged polypeptides on a charged surface are known from previous studies to comprise a mixture of types of secondary structure. Here, study of the perturbation of polypeptide film structure by deposition of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) on the film surface has revealed differences in behavior attributable to physical properties of the peptides. The methods of analysis were circular dichroism spectroscopy (CD), ultraviolet spectroscopy (UVS), and quartz crystal microbalance (QCM). Films made of poly(L-lysine) (PLL) and poly(L-glutamic acid) (PLGA) with an average charge per monomer of about 1 were substantially more susceptible to perturbation of structure than films made of designed polypeptides with an average charge per monomer of about 0.5, despite preparation under identical conditions. PLL-PLGA films showed loss or gain of material and change in secondary structure content on perturbation, whether made of high molecular mass (ca. 90 kDa) or low molecular mass (ca. 14 kDa) polymers. By contrast, films made of very low molecular mass (ca. 3.5 kDa) designed polypeptides showed little change in secondary structure content. The data suggest that the penetrability of PSS or PAH into a film and therefore film density can depend substantially on the polypeptides of which it is made and the character of intermolecular interactions.

Amino Acid Sequence↗
PubMed2005

Nestin-positive progenitor cells isolated from human fetal pancreas have phenotypic markers identical to mesenchymal stem cells.

AIM: To isolate nestin-positive progenitor cells from human fetal pancreas and to detect their surface markers and their capability of proliferation and differentiation into pancreatic islet endocrine cells in vitro. METHODS: Islet-like cell clusters (ICCs) were isolated from human fetal pancreas by using collagenase digestion. The free-floating ICCs were handpicked and cultured in a new dish. After the ICCs developed into monolayer epithelium-like cells, they were passaged and induced for differentiation. Reverse transcription polymerase chain reaction (RT-PCR), immunofluorescence stain, fluorescence-activated cell sorting (FACS) and radioimmunoassay (RIA) were used to detect the expression of cell markers. RESULTS: (1) The monolayer epithelium-like cells had highly proliferative potential and could be passaged more than 16 times in vitro; (2) RT-PCR analysis and immunofluorescence stain showed that these cells expressed both nestin and ABCG2, two of stem cell markers; (3) FACS analysis revealed that CD44, CD90 and CD147 were positive, whereas CD34, CD38, CD45, CD71, CD117, CD133 and HLA-DR were negative on the nestin-positive cells; (4) RT-PCR analysis showed that the mRNA expression of insulin, glucagon and pancreatic-duodenal homeobox gene-1 was detected, whereas the expression of nestin and neurogenin 3 disappeared in these cells treated with serum-free media supplemented with the cocktail of growth factors. Furthermore, the intra-cellular insulin content was detected by RIA after the induction culture. CONCLUSION: Nestin-positive cells isolated from human fetal pancreas possess the characteristics of pancreatic progenitor cells since they have highly proliferative potential and the capability of differentiation into insulin-producing cells in vitro. Interestingly, the nestin-positive pancreatic progenitor cells share many phenotypic markers with mesenchymal stem cells derived from bone marrow.

Biomarkers↗
PubMed2005

[Analysis of the treatment of unexpected gallbladder cancer].

OBJECTIVE: To investigate the secondary operation methods and the effects on the prognosis of unexpected gallbladder cancer (UGC). METHODS: A retrospective analysis on the clinical data was made for 41 patients who underwent extended radical excision from June 1995 to December 2002. Among the patients, 12 were male, 29 were female. The average age was 51 years old. The 41 patients had undergone gallbladder excision because of cholecystitis complicated lithiasis of gallbladder (32 cases), polypi of gallbladder or adenoma (9 cases). Postoperative pathology showed that 32 cases were adenocarcinoma of gallbladder, 6 cases were squamous carcinoma, 3 cases were squamous adenocarcinoma. Six cases were on the stage of Nevin I, 16 on Nevin II, 17 on Nevin III, 2 on Nevin IV. The second operation was performed after 6-30 d of the first operation. The second operation chose the improved method of Glenn excision of carcinoma of gallbladder. RESULTS: On the second operation, 14 cases were with lymphatic metastasis, 14 with gallbladder metastasis, 6 with bile duct metastasis, 2 with pancreas metastasis. Fourteen cases were on the stage of Nevin IV, 9 on Nevin V, none on Nevin I, II and III. After the second operation, 1 year survival rate was 100% (41 cases); The three-year survival rate was 53.8% (22 cases); The five-year survival rate was 17.5% (7 cases). CONCLUSION: Extended radical excision is one of the most important methods for the treatment of UGC.

Adult↗
PubMed2005

Pressure dependence of the vapor-liquid-liquid phase behavior in ternary mixtures consisting of n-alkanes, n-perfluoroalkanes, and carbon dioxide.

Expansion of an organic solvent by an inert gas can be used to tune the solvent's liquid density, solubility strength, and transport properties. In particular, gas expansion can be used to induce miscibility at low temperatures for solvent combinations that are biphasic at standard pressure. Configurational-bias Monte Carlo simulations in the Gibbs ensemble were carried out to investigate the vapor-liquid-liquid equilibria and microscopic structures for two ternary systems: n-decane/n-perfluorohexane/CO2 and n-hexane/n-perfluorodecane/CO2. These simulations employed the united-atom version of the transferable potential for phase equilibria (TraPPE-UA) force field. Initial simulations for binary mixtures of n-alkanes and n-perfluoroalkanes showed that special mixing parameters are required for the unlike interactions of CHx and CFy pseudoatoms to yield satisfactory results. The calculated upper critical solution pressures for the ternary mixtures at a temperature of 298 K are in excellent agreement with the available experimental data and predictions using the SAFT-VR (statistical associating fluid theory of variable range) equation of state. The simulations yield asymmetric compositions for the coexisting liquid phases and different degrees of microheterogeneity as measured by local mole fraction enhancements.

Journal Article↗