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Biomedical subjects

Ling Xue

Publications and source records attributed to Ling Xue.

At least 19 recordsLinked to original sources
PubMed2005

Activation and potentiation of interferon-gamma signaling by 3,3'-diindolylmethane in MCF-7 breast cancer cells.

3,3'-Diindolylmethane (DIM), a natural autolytic product in plants of the Brassica genus, including broccoli, cauliflower, and Brussels sprouts, exhibits promising cancer protective activities, especially against mammary neoplasia in animal models. We observed previously that DIM induced a G(1) cell-cycle arrest and strong induction of cell-cycle inhibitor p21 expression and promoter activity in both estrogen-responsive and -independent breast cancer cell lines. We showed recently that DIM up-regulates the expression of interferon gamma (IFNgamma) in human MCF-7 breast cancer cells. This novel effect may contribute to the anticancer effects of DIM because IFNgamma plays an important role in preventing the development of primary and transplanted tumors. In this study, we observed that DIM activated the IFNgamma signaling pathway in human breast cancer cells. DIM activated the expression of the IFNgamma receptor (IFNGR1) and IFNgamma-responsive genes p56- and p69-oligoadenylate synthase (OAS). In cotreatments with IFNgamma, DIM produced an additive activation of endogenous p69-OAS and of an OAS-Luc reporter and a synergistic activation of a GAS-Luc reporter. DIM synergistically augmented the IFNgamma induced phosphorylation of signal transducer and activator of transcription factor 1, further evidence of DIM activation of the IFNgamma pathway. DIM and IFNgamma produced an additive inhibition of cell proliferation and a synergistic increase in levels of major histocompatibility complex class-1 (MHC-1) expression, accompanied by increased levels of mRNAs of MHC-1-associated proteins and transporters. These results reveal novel immune activating and potentiating activities of DIM in human tumor cells that may contribute to the established effectiveness of this dietary indole against various tumors types.

2',5'-Oligoadenylate Synthetase↗
PubMed2005

Determination of saikosaponins a, c, and d in Bupleurum Chinese DC from different areas by capillary zone electrophoresis.

A fast capillary zone electrophoresis (CZE) method was developed for the determination and separation of saikosaponins a, c, and d in Chinese herbal extracts of Bupleurum Chinese DC from different areas. Detection at 214 nm with a system containing sodium borate buffer and mono-3-phenylcarbamoyl-beta-CD was found to be the most suitable approach for this analysis. Saikosaponins a, c, and d could be easily determined within 8 min. The effect of the concentration of mono-3-phenylcarbamoyl-beta-CD, the concentration of the running buffer and buffer pH value on the migration behavior of the saikosaponins is discussed.

Borates↗
PubMed2005

Effects of analogs of indole-3-carbinol cyclic trimerization product in human breast cancer cells.

5,6,11,12,17,18-Hexahydrocyclonona[1,2-b:4,5-b*:7,8-b**]triindole (CTr) is a major digestive product of indole-3-carbinol (I3C) from Brassica vegetables and exhibits strong estrogenic activities. CTr increases proliferation of estrogen-dependent breast tumor cells, binds with strong affinity for the estrogen receptor-alpha (ERalpha), and activates expression of estrogen (E(2))-dependent genes. To begin to examine the structural features that determine the biological activity of CTr, we prepared and studied the effects of two analogs, 9,18-dihydro-12H-[1,2,5]trithionino[3,4-b:6,7-b*:9,8-b**]triindole (S(3)CTr) and 5,6,11,12,17,18-hexahydro-5,11,17-trimethylcyclonona[1,2-b:4,5-b*:7,8-b**]triindole (Me(3)CTr). N-Methylation of CTr completely ablated the estrogenic activities of CTr. In the dose range in which CTr was clearly estrogenic, Me(3)CTr exhibited no detectable effect on cell growth, ERalpha binding to E(2), or ERalpha-responsive gene expression. S(3)CTr showed mixed ERalpha agonist activities. It bound to the ERalpha and activated receptor binding with DNA, weakly activated expression of transfected E(2)-responsive reporter gene constructs, and strongly inhibited the E(2)-induced activation of these reporter constructs. S(3)CTr activated aryl hydrocarbon receptor (AhR)-mediated pathways, consistent with the moderately strong binding affinity of S(3)CTr for the AhR. Comparisons of the conformational characteristics among CTr and its two analogs indicated that the estrogenic effects of CTr are highly sensitive to apparently minor structural modifications, and further supported the hypothesis for a central role of hydrogen bonding around the nitrogen atom in CTr binding to the ligand binding site of ERalpha.

Animals↗
PubMed2005

DIM stimulates IFNgamma gene expression in human breast cancer cells via the specific activation of JNK and p38 pathways.

3,3'-Diindolylmethane (DIM) is a promising anticancer agent derived from Brassica vegetables, but the mechanisms of DIM action are largely unknown. We have shown that DIM can upregulate the expression and stimulate the secretion of interferon-gamma (IFNgamma) in the human MCF-7 breast cancer cell line. This novel effect may provide important clues to explain the anticancer effects of DIM because it is well known that IFNgamma plays an important role in preventing the development of primary and transplanted tumors. Utilizing promoter deletions, we show here that the region between -108 and -36 bp in the IFNgamma promoter, which contains two conserved and essential regulatory elements, is required for DIM-induced IFNgamma expression. DIM activates both JNK and p38 pathways, induces the phosphorylation of c-Jun and ATF-2, and increases the binding of the homodimer or heterodimer of c-Jun/ATF-2 to the proximal AP-1.CREB-ATF-binding element. Moreover, studies with specific enzyme inhibitors showed that up-stream Ca2+-dependent kinase(s) is required for the inducing effects of DIM in MCF-7 cells. These results establish that DIM-induced IFNgamma expression in human breast tumor cells is mediated by activation of both JNK and p38 pathways, which is ultimately dependent on intracellular calcium signaling.

Activating Transcription Factor 2↗
PubMed2005

[Pathologic diagnosis of 1123 post-transplant liver biopsies from 665 liver transplant patients].

OBJECTIVE: To summarize the Chinese experience in pathologic diagnosis of liver biopsies after orthotopic liver transplantation (OLTx). METHODS: 1123 post-transplant liver biopsies from 665 OLTx patients from the Shanghai Eastern Hepatobiliary Surgery Hospital, Tianjin First Central Hospital, Guangzhou Sun Yat-sen University and Chongqing Southwest Hospital were retrospectively analyzed. All liver biopsies were stained with hematoxylin and eosin. Immunohistochemical studies for cytomegalovirus, HBsAg, CK19, CD4 and CD8 were also performed in selected examples. RESULTS: In the involved hospitals, 4 to 12 types of complications were encountered after OLTx. The number of liver biopsies performed for each patient ranged from 1 to 9 (mean = 2.2). The timing of these biopsies varied from the second to the 2877 th post-transplant day. The 5 most common complications were acute cellular rejection (35.6%), ischemic-reperfusion injury (13.4%), biliary stricture (5.6%), drug complication (5.0%) and chronic rejection (4.7%). The 5 earliest complications after OLTx were primary non-function (occurring at day 4.7 +/- 2.1), ischemic-reperfusion injury (occurring at day 14.0 +/- 4.0), acute cellular rejection (occurring at day 32.1 +/- 62.9), hepatic artery thrombosis / stricture (occurring at day 62.9 +/- 74.2) and cytomegalovirus infection (occurring at day 107.7 +/- 93.0). CONCLUSIONS: This study has evaluated the types, incidence and timing of major complications occurring after OLTx. The most important issue is the distinction between rejection and non-rejection pathology. Thorough understanding of atypical pathologic features of these complications is necessary. The Banff Schema (rejection activity index) for grading liver allograft rejection is useful for monitoring anti-rejection therapy and should be used routinely.

Adolescent↗
PubMed2004

Identification of structurally diverse growth hormone secretagogue agonists by virtual screening and structure-activity relationship analysis of 2-formylaminoacetamide derivatives.

Two molecules with known growth hormone secretagogue (GHS) agonist activity were used as templates to computationally screen approximately 80000 compounds. A total of 108 candidate compounds were selected, and five of them were found to be active in the low-micromolar range in both cell-based and direct binding assays. These compounds were structurally diverse and significantly differed from known GHS agonists. The most active compound was subjected to SAR evaluation, which slightly increased its potency and identified molecular regions important for specific GHS agonist activity.

Acetamides↗
PubMed2004

Influence of serum from liver-damaged rats on differentiation tendency of bone marrow-derived stem cells.

AIM: Recent studies in both rodents and humans indicated that bone marrow (BM)-derived stem cells were able to home to the liver after they were damaged and demonstrated plasticity in becoming hepatocytes. However, the question remains as to how these stem cells are activated and led to the liver and where the signals initiating the mechanisms of activation and differentiation of stem cells originate. The aim of this study was to investigate the influence of serum from liver-damaged rats on differentiation tendency of bone marrow-derived stem cells. METHODS: Serum samples were collected from rats treated with a 2-acetylaminofluorene (2-AAF) /carbon tetrachloride (CCl(4)) program for varying time points and then used as stimulators of cultured BM stem cells. Expression of M(2)- and L-type isozymes of rat pyruvate kinase, albumin as well as integrin-beta1 were then examined by reverse transcription polymerase chain reaction (RT-PCR) to estimate the differentiation state of BM stem cells. RESULTS: Expression of M(2)-type isozyme of pyruvate kinase (M(2)-PK), a marker of immature hepatocytes, was detected in each group stimulated with experimental serum, but not in controls including mature hepatocytes, BM stem cells without serum stimulation, and BM stem cells stimulated with normal control serum. As a marker expressed in the development of liver, the expression signal of integrin-beta1 was also detectable in each group stimulated with experimental serum. However, expression of L-type isozyme of pyruvate kinase (L-PK) and albumin, marker molecules of mature hepatocytes, was not detected in groups stimulated with experimental serum. CONCLUSION: Under the influence of serum from rats with liver failure, BM stem cells begin to differentiate along a direction to hepatocyte lineage and to possess some features of immature hepatocytes.

Animals↗
PubMed2004

Is inhibition of cancer angiogenesis and growth by paclitaxel schedule dependent?

It has been speculated that weekly paclitaxel enhances antiangiogenesis and, hence, results in a greater inhibition of cancer growth than the 3-week schedule. We compared the weekly and 3-week schedules of paclitaxel in inhibiting angiogenesis, tumor growth and bone marrow hematopoiesis in a lung cancer model. Vehicle or paclitaxel was administered i.p. to three groups of nude mice bearing a human lung cancer. The vehicle was given weekly for six doses or every 3 weeks for two doses (Group A). Paclitaxel was administered at 20 mg/kg/week for six doses (Group B) or 60 mg/kg/3 weeks for two doses (Group C). The tumor growth rate was reduced by 50% equally in both the paclitaxel-treated groups. Intratumoral microvasculature was reduced by 70% in each paclitaxel-treated group. However, white blood cell count was significantly reduced in Group C in comparison with that of Group A or B. We conclude that in this model, angiogenesis and tumor growth were inhibited to the same extent when paclitaxel was administered on a weekly or 3-week schedule. Inhibition of tumor growth by paclitaxel was associated with suppression of angiogenesis. Weekly administration of paclitaxel resulted in a lower degree of leukopenia than with the 3-week schedule, mimicking the clinical setting.

Angiogenesis Inhibitors↗
PubMed2004

Cell-based partitioning.

Partitioning techniques are widely used to classify compound sets or databases according to specific chemical or biological criteria. Partitioning is conceptually related to, yet algorithmically distinct from, conventional clustering methods and is particularly suitable for efficient processing of very large compound sets. Currently, some of the most popular partitioning approaches in the chemoinformatics field involve dimension reduction of initially defined chemistry spaces and creation of subsections of low-dimensional space for molecular classification. These subsections are often called cells. Original chemical reference spaces are generated through selection of various descriptors of molecular structure and properties. Principles and methodological aspects of dimension reduction of chemical spaces and compound partitioning in low-dimensional space are described herein.

Information Services↗
PubMed2003

A selective tropism of transfused oval cells for liver.

AIM: To explore the biological behaviors of hepatic oval cells after transfused into the circulation of experimental animals. METHODS: Oval cells from male SD rat were transfused into the circulation of a female rat which were treated by a 2-AAF/CCl(4) program, through caudal vein. Sex-determining gene sry which located on Y chromosome was examined by PCR and in situ hybridization technique in liver, kidney and spleen of the experimental animals, respectively. RESULTS: The results of the cell-transplant experiment showed that the sry gene was detectable only in the liver but not in spleen and kidney of the experimental rats, and no signals could be detected in the control animals. It can be also morphologically proved that some exogenous cells had migrated into the parenchyma of the liver and settled there. CONCLUSION: The result means that there are exogenous cells located in the liver of the experimental animal and the localization is specific to the liver. This indicates that some "signal molecules" must exist in the circulation of the rats treated by 2-AAF/CCl(4). These "signal molecules" might play an important role in specific localization and differentiation of transfused oval cells.

Animals↗
PubMed2002

Methods for compound selection focused on hits and application in drug discovery.

In the context of virtual screening calculations, a multiple fingerprint-based metric is applied to generate focused compound libraries by database searching. Different fingerprints are used to facilitate a similarity step for database mining, followed by a diversity step to assemble the final library. The method is applied, for example, to build libraries of limited size for hit-to-lead development efforts. In studies designed to inhibit a therapeutically relevant protein-protein interaction, small molecular hits were initially obtained by combined fingerprint- and structure-based virtual screening and used for the design of focused libraries. We review the applied virtual screening approach and report the statistics and results of screening as well as focused library design. While the structures of lead compounds cannot be disclosed, the analysis is thought to provide an example of the interplay of different methods applied in practical lead identification.

Binding Sites↗
PubMed2002

[Studies on the anti-inflammation effect of the TCM prescription of a combination of monkshood root with peony root].

OBJECTIVE: To make a comparison between the single and combined use of Monkshood Root and Peony Root to observe the anti-inflammation effect in the experimental animals. METHOD: The experimental inflammatory models were adopted, i.e. adjuvant-induced polyarthritis carrageenan-induced or formaldehyde-induced rat paw edema, and cotton pellet-induced granuloma formation in rats xylene-induced mouse ear edema, exudation of abdominal blood capillaries of mice, etc. RESULT: The anti-inflammafion effect of Monkshood Root was weaker than that of Peony Root or Peony Root combined with Monkshood Root. It was found that anti-inflammation effect with the drug-cooperation was enhanced more significantly in the formaldehyde-induced or adjuvant-induceed arthritis models than in the carrageenan-induced rat paw edema and other inflammatory models either in the large dosage of 1:1 proportion or in the small dosage of 1:2 proportion. CONCLUSION: The drug-cooperation has a good selective and synergic effect on anti-inflammation.

Aconitum↗
PubMed1998

In situ hybridization assay of androgen receptor gene in hepatocarcinogenesis.

AIM:To determine the correlation between expression of androgen receptor (AR) gene and hepatocarcinogenesis.METHODS:Male SD rats were used as experimental animals and the animal model of experimental hepatocarcinoma was established by means of 3'-me-DAB administration. Androgen receptor mRNA was detected by a non-radioactive in situ hybridization assay in neoplastic and non-neoplastic liver tissues.RESULTS:The expression of androgen receptor mRNA was observed only in neoplastic cells and some atypical hyperplastic cells. In the liver tissue of control animal and the remaining normal liver cells adjacent to the carcinoma tissue, no positive signal was seen.CONCLUSION:Androgen has an important correlation with hepatocarcinogenesis and the expression of androgen receptor gene might be a mark event during hepatocarcinogenesis.

Journal Article↗
PubMedDate not supplied

Accurate partitioning of compounds belonging to diverse activity classes.

Diverse sets of compounds were classified according to biological activity by use of a partitioning approach based on principal component analysis in conjunction with a genetic algorithm for molecular descriptor evaluation. Combinations of 236 molecular property and structural key descriptors were explored for their performance in classifying 317 molecules belonging to 21 distinct biological activity classes from various sources. Preferred descriptor combinations were further explored by complete factorial analysis. In these calculations, compounds having similar specific activity were predicted with greater than 80% accuracy.

Journal Article↗
PubMedDate not supplied

Median Partitioning: a novel method for the selection of representative subsets from large compound pools.

A method termed Median Partitioning (MP) has been developed to select diverse sets of molecules from large compound pools. Unlike many other methods for subset selection, the MP approach does not depend on pairwise comparison of molecules and can therefore be applied to very large compound collections. The only time limiting step is the calculation of molecular descriptors for database compounds. MP employs arrays of property descriptors with little correlation to divide large compound pools into partitions from which representative molecules can be selected. In each of n subsequent steps, a population of molecules is divided into subpopulations above and below the median value of a property descriptor until a desired number of 2n partitions are obtained. For descriptor evaluation and selection, an entropy formulation was embedded in a genetic algorithm. MP has been applied here to generate a subset of the Available Chemicals Directory, and the results have been compared with cell-based partitioning.

Algorithms↗
PubMedDate not supplied

Classification of biologically active compounds by median partitioning.

The median partitioning (MP) method was originally developed for the selection of diverse subsets from compound databases. Following this approach, property descriptors are used in subsequent steps to divide compounds into defined partitions from which representative molecules are selected. For descriptor analysis, MP was coupled to a genetic algorithm. MP subset selection does not depend on pairwise comparison of molecules and is therefore applicable to very large compound pools. Here the MP approach was evaluated for the classification of molecules according to biological activity. A total of 317 molecules belonging to 21 different activity classes were studied. MP compound classification calculations were carried out both in the presence and absence of 2000 randomly selected "background" molecules. The performance of MP was compared to cell-based partitioning and found to be at least comparable, with up to approximately 82% of active molecules occurring in "pure" partitions consisting only of molecules sharing the same activity. Different from cell-based methods, MP classification is based on "direct" and "sequential" contributions of molecular property descriptors. Our results suggest that MP in not only an effective method for the selection of diverse subsets but also for the classification of active compounds and searching for molecules with desired activity.

Computer Simulation↗
PubMedDate not supplied

Design and evaluation of a molecular fingerprint involving the transformation of property descriptor values into a binary classification scheme.

A new fingerprint design concept is introduced that transforms molecular property descriptors into two-state descriptors and thus permits binary encoding. This transformation is based on the calculation of statistical medians of descriptor distributions in large compound collections and alleviates the need for value range encoding of these descriptors. For binary encoded property descriptors, bit positions that are set off capture as much information as bit positions that are set on, different from conventional fingerprint representations. Accordingly, a variant of the Tanimoto coefficient has been defined for comparison of these fingerprints. Following our design idea, a prototypic fingerprint termed MP-MFP was implemented by combining 61 binary encoded property descriptors with 110 structural fragment-type descriptors. The performance of this fingerprint was evaluated in systematic similarity search calculations in a database containing 549 molecules belonging to 38 different activity classes and 5000 background molecules. In these calculations, MP-MFP correctly recognized approximately 34% of all similarity relationships, with only 0.04% false positives, and performed better than previous designs and MACCS keys. The results suggest that combinations of simplified two-state property descriptors have predictive value in the analysis of molecular similarity.

Computing Methodologies↗