Biomedical subjects

W Tong

Publications and source records attributed to W Tong.

At least 37 records · Page 2Linked to original sources

PubMed2000

Heat shock proteins' mRNA expression in asthma.

OBJECTIVE: The aim of the present study was to investigate the expression levels of heat shock proteins (HSP) mRNA in the peripheral blood mononuclear cells (PBMC) of patients with asthma and chronic bronchitis to elucidate the role of HSP in the pathogenesis of asthma and chronic bronchitis. METHOD: Using reverse transcription-DNA polymerase chain reaction, the expression levels of HSP70, HSP90alpha and HSP90beta genes in PBMC in normal state and after heat shock were investigated. RESULTS: No HSP70 gene but HSP90alpha and HSP90beta expressions were found in non-heat-shocked PBMC of normal controls; HSP90alpha and HSP90beta genes may be expressed in PBMC of all patients, independently of acute episodes. Expression of HSP70 was found in PBMC of asthmatic patients in acute episodes and three symptom-free patients with Aas 3, step 2. Among patients with chronic bronchitis, no HSP70 gene expression was found in PBMC of patients in convalescent period but in PBMC of patients in acute episode. HSP90alpha and HSP90beta genes were expressed in PBMC of both patient groups. After heat shock, expressions of the three genes increased significantly in PBMC of both normal controls and patients. CONCLUSION: Expression of HSP70 gene in PBMC of asthmatic and chronic bronchitis patients was different, indicating that HSP, especially HSP70, might be involved in the pathogenesis of asthma.

Adult↗

PubMed2000

The estrogen receptor relative binding affinities of 188 natural and xenochemicals: structural diversity of ligands.

We have utilized a validated (standardized) estrogen receptor (ER) competitive-binding assay to determine the ER affinity for a large, structurally diverse group of chemicals. Uteri from ovariectomized Sprague-Dawley rats were the ER source for the competitive-binding assay. Initially, test chemicals were screened at high concentrations to determine whether a chemical competed with [3H]-estradiol for the ER. Test chemicals that exhibited affinity for the ER in the first tier were subsequently assayed using a wide range of concentrations to characterize the binding curve and to determine each chemical's IC50 and relative binding affinity (RBA) values. Overall, we assayed 188 chemicals, covering a 1 x 10(6)-fold range of RBAs from several different chemical or use categories, including steroidal estrogens, synthetic estrogens, antiestrogens, other miscellaneous steroids, alkylphenols, diphenyl derivatives, organochlorines, pesticides, alkylhydroxybenzoate preservatives (parabens), phthalates, benzophenone compounds, and a number of other miscellaneous chemicals. Of the 188 chemicals tested, 100 bound to the ER while 88 were non-binders. Included in the 100 chemicals that bound to the ER were 4-benzyloxyphenol, 2,4-dihydroxybenzophenone, and 2,2'-methylenebis(4-chlorophenol), compounds that have not been shown previously to bind the ER. It was also evident that certain structural features, such as an overall ring structure, were important for ER binding. The current study provides the most structurally diverse ER RBA data set with the widest range of RBA values published to date.

Animals↗

PubMed2000

Huanglian, A chinese herbal extract, inhibits cell growth by suppressing the expression of cyclin B1 and inhibiting CDC2 kinase activity in human cancer cells.

Huanglian is an herb that is widely used in China for the treatment of gastroenteritis. We elected to determine whether huanglian could inhibit tumor cell growth by modulating molecular events directly associated with the cell cycle. Huanglian inhibited tumor growth and colony formation of gastric, colon, and breast cancer cell lines in a time- and dose-dependent manner. Cell growth was completely inhibited after 3 days of continuous drug exposure to 10 microg/ml of herb. This degree of growth inhibition was significantly greater than that observed with berberine, the major constituent of the herb. The inhibition of cell growth by huanglian was associated with up to 8-fold suppression of cyclin B1 protein. This resulted in complete inhibition of cdc2 kinase activity and accumulation of cells in G(2). The mRNA expression of cyclin B1 was not changed after huanglian treatment. There was no change in the protein expression of cyclins A or E. Therefore, the effect of huanglian on inhibiting tumor growth seems to be mediated by the selective suppression of cyclin B1, which results in the inhibition of cdc2 kinase activity. Inhibition of cyclin dependent kinase (cdk) activity is emerging as an attractive target for cancer chemotherapy. Huanglian represents a class of agents that can inhibit tumor cell growth by directly suppressing the expression of a cyclin subunit that is critical for cell cycle progression. These results indicate that traditional Chinese herbs may represent a new source of agents designed for selective inhibition of cyclin dependent kinases in cancer therapy.

Antineoplastic Agents↗

PubMed2000

Rationalised prescribing for community acquired pneumonia: a closed loop audit.

AIMS: To audit the management of community acquired pneumonia before and after the introduction of a protocol. To determine the aetiology of pneumonia using routine investigations and polymerase chain reaction (PCR). METHODS: Retrospective and prospective audit following the introduction of a management protocol. Prospective cases were investigated routinely and with PCR on blood and nasopharyngeal aspirate. RESULTS: There was a significant increase in rational prescribing following introduction of the protocol with 75% of children receiving intravenous penicillin or erythromycin compared with 26% beforehand. Of 89 children in the prospective group, 51 microbiological diagnoses were achieved in 48 children. Seven children had Streptococcus pneumoniae infection, 14 had Mycoplasma infection, six had pertussis, and one had Chlamydia pneumoniae infection. Twenty three children had a viral cause of which respiratory syncytial virus was commonest. CONCLUSIONS: Introduction of the protocol led to improved prescribing. PCR increased the diagnostic yield and the results support the management protocol.

Adolescent↗

PubMed2000

Quantitative comparisons of in vitro assays for estrogenic activities.

Substances that may act as estrogens show a broad chemical structural diversity. To thoroughly address the question of possible adverse estrogenic effects, reliable methods are needed to detect and identify the chemicals of these diverse structural classes. We compared three assays--in vitro estrogen receptor competitive binding assays (ER binding assays), yeast-based reporter gene assays (yeast assays), and the MCF-7 cell proliferation assay (E-SCREEN assay)--to determine their quantitative agreement in identifying structurally diverse estrogens. We examined assay performance for relative sensitivity, detection of active/inactive chemicals, and estrogen/antiestrogen activities. In this examination, we combined individual data sets in a specific, quantitative data mining exercise. Data sets for at least 29 chemicals from five laboratories were analyzed pair-wise by X-Y plots. The ER binding assay was a good predictor for the other two assay results when the antiestrogens were excluded (r(2) is 0.78 for the yeast assays and 0.85 for the E-SCREEN assays). Additionally, the examination strongly suggests that biologic information that is not apparent from any of the individual assays can be discovered by quantitative pair-wise comparisons among assays. Antiestrogens are identified as outliers in the ER binding/yeast assay, while complete antagonists are identified in the ER binding and E-SCREEN assays. Furthermore, the presence of outliers may be explained by different mechanisms that induce an endocrine response, different impurities in different batches of chemicals, different species sensitivity, or limitations of the assay techniques. Although these assays involve different levels of biologic complexity, the major conclusion is that they generally provided consistent information in quantitatively determining estrogenic activity for the five data sets examined. The results should provide guidance for expanded data mining examinations and the selection of appropriate assays to screen estrogenic endocrine disruptors.

Binding, Competitive↗

PubMed2000

Phase I and pharmacokinetic study of 10-propargyl-10-deazaaminopterin, a new antifolate.

The 10-deazaaminopterins are a new class of rationally designed antifolates demonstrating greater antitumor effects than methotrexate in murine tumor models and human tumor xenografts. Their design was aimed at improving membrane transport and polyglutamylation in tumor cells, resulting in increased intracellular accumulation and enhanced cytotoxicity. Compared with other 4-aminofolate analogues, 10-propargyl-10-deazaaminopterin (PDX) is the most efficient permeant for the RFC-1-mediated internalization and substrate for folylpolyglutamate synthetase. PDX demonstrates greater in vitro and in vivo antitumor efficacy than methotrexate or edatrexate. We undertook a Phase I study with PDX to identify the potential toxicities and define an optimal dose and schedule. Thirty-three patients were enrolled, all of whom had non-small cell lung cancer (NSCLC) and were treated previously with a median of two prior chemotherapy regimens. Initially, PDX was administered weekly for 3 weeks in a 4-week cycle. Mucositis requiring dose reduction and/or delay in the first cycle occurred in four of six patients treated at the initial dose level (30 mg/m2), making this the maximal tolerated dose for PDX given on this schedule. The treatment schedule was then modified to every 2 weeks. Twenty-seven patients were treated twice weekly with a total of 102 four-week cycles (median, 2 cycles/patient). Mucositis was the dose-limiting toxicity, with grade 3 and 4 mucositis occurring in the first two patients treated at the 170 mg/m2 dose level. Other toxicities were mild and reversible. No neutropenia was observed. The recommended Phase II dose is 150 mg/m2 biweekly. At that dose level, the mean area under the curve was 20.6 micromol x h, and the mean terminal half-life was 8 h. Two patients with stage IV NSCLC had major objective responses, and five patients had stable disease for 7 (two patients), 9 (one patient), 10 (one patient), and 13 months (one patient). PDX is a new antifolate with manageable toxicity and evidence of antitumor activity in NSCLC. A Phase II trial in NSCLC and a Phase I trial with paclitaxel are under way. These studies will also quantitate the expression of genes controlling internalization (RFC-1) and polyglutamylation of PDX in tumor cells as correlates of response.

Aminopterin↗

PubMed2000

Heat shock proteins mRNA expressions by peripheral blood mononuclear cells in asthma and chronic bronchitis.

OBJECTIVE: To investigate the manifestations that heat shock proteins(HSPs) possess in the pathogenesis of asthma and chronic bronchitis. METHODS: Using reverse transcription-DNA polymerase chain reaction (RT-PCR), we investigated the expression levels of HSP70, HSP90 alpha and HSP90 beta genes in peripheral blood mononuclear cells(PBMC) at natural state and after heat shock in 14 healthy volunteers, 21 patients with asthma and 18 patients with chronic bronchitis. RESULTS: No HSP70 gene but HSP90 alpha and HSP90 beta expressions were found in non-heat-shocked PBMC of normal control; HSP90 alpha and HSP90 beta genes may be expressed in PBMC of patients no matter whether they were in acute episode or not. Expression of HSP70 was found in PBMC of patients in acute episodes and of three symptoms-free patients with Aas 3, step 2. No expression of HSP70 gene was found in PBMC of patients in convalescent period but in PBMC of patients in acute episode. HSP90 alpha and HSP90 beta genes were expressed in PBMC of the two patients groups; After heat shock, expressions of the three genes increased in amount significantly in PBMC of all normal controls and patients. CONCLUSION: Expression of HSP70 gene in PBMC of asthmatic patients and chronic bronchitis was different, indicating that HSPs, especially HSP70 might be involved in the pathogenesis of asthma.

Adult↗

PubMed2000

[Study on the antitumor effect of angiostatin on LA795 adenocarcinoma cells].

OBJECTIVE: To study the antitumor effect of angiostatin on LA795 adenocarcinoma cells inoculated on T739 mice. METHODS: Affinity chromatography purified plasminogen was digested by pancreatic elastase and angiostatin was obtained by purifying the digestion with affinity chromatography and dialysis. T739 mice were inoculated with LA795 cells. Angiostatin was given to part of inoculated and uninoculated mice by intraperitoneal injection fourteen days after the inoculation. The treatment lasted 20 days and the size of tumor, survival period, behavior of the mice and pathology of lungs, livers and kidneys were observed. RESULTS: The size of tumor decreased from (2.35 +/- 0.26) cm to (0.97 +/- 0.34) cm after angiostatin treatment. The number of metastases in lung was significantly fewer in angiostatin treated mice than in untreated ones, which lived much shorter. No obvious side effects were observed. CONCLUSION: Angiostatin markedly inhibits the growth and metastasis of LA795 cells on T739 mice and no obvious side effects of angiostatin were found during the treatment.

Adenocarcinoma↗

PubMed2000

[A preliminary study of viral cross-transmission in dentistry].

OBJECTIVE: To research the viral cross-transmission of a DNA virus (HBV) and a RNA virus (HCV) in dentistry. METHODS: Five plans were designed to sterilize the oral instruments that had been infected with HBV or HCV positive serum. HBsAg, HBV-DNA, anti-HCV, HCV-RNA were detected before and after sterilization. RESULTS: All methods could effectively clean the specific proteins (HBsAg/anti-HCV) and nucleic acids (HBV-DNA/HCV-RNA) of the infected virus. CONCLUSION: The instruments which have been sterilized should not be the main way of the cross-transmission of virus in dentistry.

Antigens, Viral↗

PubMed2000

[Persistence of hepatitis C virus type II in patient's peripheral blood B lymphocytes transformed by Epstein-Barr virus].

OBJECTIVE: To study the persistence and replication of hepatitis C virus (HCV)-RNA in human peripheral blood B cells transformed by Epstein-Barr virus (EBV) and cultured in vitro. METHODS: EBV was used for infecting B lymphocytes from one hepatitis C patient with HCV positive in the peripheral blood mononuclear cells (PBMC) and transforming them into lymphoblasts capable of being propagated indefinitely. Then, HCV RNA of the cultured cells and supernatants was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) every one month. HCV gene was typed by enzyme separating method. Electron microscopy and immunoelectron microscopy were employed to locate HCV in the cells and observe the character of its configuration. RESULTS: HCV positive-strand RNA was detected in the cultured cells for 1 year. Interestingly, the HCV positive-strand RNA was identified in supernatants and the negative-strand RNA was also observed in the cultured cells intermittently. HCV gene was type II. Electron microscopy observed HCV spherical virus-like particles with a diameter of approximately 45 nm to 70 nm, individual particles 110 nm, in the LCL cytoplasmic vesicles. CONCLUSION: HCV may exist in the cultured cell line for a longer period and reproduce in and secrete out of them. HCV locates mainly in the cytoplasm. The cell line might be useful in analyzing the mechanisms of HCV persistence in PBMC.

5' Untranslated Regions↗

PubMed2000

[Characteristic immunodeficiency syndrome of rapid fatal type of simian immunodeficiency virus infected monkeys].

OBJECTIVE: To observe the characteristic immunodeficiency syndrome of the rapid fatal type of simian immunodeficiency virus (SIV) infected monkeys. METHODS: Eighty rhesus monkeys and 4 cynomolgus monkeys were intravenously inoculated with SIVmac or SIVmac251. The virus isolation and viral titer, estimation by indirect immunofluroresence and viral antibody were determined periodically from monkeys' plasma; lymph node biopsies were performed for pathohistological examination. RESULTS: Twelve out of 84 macaque (14.2%) died of rapid progressive type after inoculation of SIVmac and SIVmac251 in the duration 3 to 4 months. Dying monkeys showed persistent high viremia and low level titre antibody. Eight of 10 pathohistological changes showed severe depletion of lymphoid tissue in spleen and lymph nodes, there were remarkable immunodeficiency with opportunity infection. The other two monkeys appeared moderate lymphoid tissue deletion and hyperplasia without opportunity infections. The survived monkeys' (72/84) lymph nodes biopsies revealed hypoplasia of lymphoid tissue. CONCLUSIONS: The characteristic immunodeficiency syndrome of rapid fatal type of simian immunodeficiency virus infected monkeys could be made with persistent high viremia, low level antibody, severe lymphoid tissue deletion in lymph nodes and spleen, as well as complicated opportunity infections.

Acute Disease↗

PubMed1999

Angiotensin II analogues encompassing 5,9- and 5,10-fused thiazabicycloalkane tripeptide mimetics.

A simple experimental procedure on solid phase for the construction of new tripeptidic 5,9- and 5,10-fused thiazabicycloalkane scaffolds that adopt beta-turns has been developed. This N-terminal-directed bicyclization, relying on masked aldehyde precursors derived from glutamic acid as key building blocks, provides a complement to the related bicyclization previously reported, where an aspartic acid-derived precursor was employed to induce cyclization toward the C-terminal end of the peptide. Thus, the regioselectivity of the bicyclization can be altered simply by varying the chain length of the incorporated aldehyde precursor. Four analogues of the hypertensive octapeptide angiotensin II, comprising the new scaffolds in the 3-5- and 5-7-positions, were synthesized. One of these conformationally constrained angiotensin II analogues exhibited AT(1) receptor affinity (K(i) = 750 nM). Results from theoretical conformational analysis of model compounds of the bicyclic tripeptide mimetics are presented, and they demonstrate that subtle differences in geometry have a strong impact on the affinity to the AT(1) receptor.

Angiotensin II↗

PubMed1999

[Establishment of hepatitis C virus reproductive model of human peripheral blood mononuclear cells transformed by Epstein-Barr virus].

OBJECTIVE: For the present, one of the crucial questions to study pathogenic mechanism of hepatitis C and its drug therapy is to seek a suitable cell model which may support the replication of hepatitis C virus(HCV). In this article, we made effort on the study of this aspect. METHODS: Using Epstein-Barr virus(EBV), we transformed the peripheral blood mononuclear cells(PBMC) isolated from a patient diagnosed as chronic hepatitis C. HCV RNA from the cultured cells and the supernatants were analysed by reverse transcriptase-polymerase chain reaction(RT-PCR) at an intervals of one month. RESULTS: HCV positive-strand RNA could be detected continually in the cultured cells for more than one year since the establishment of the transformed PBMC clone whereas the negative-strand RNA were also observed in the cultured cells. Interestingly, the HCV positive-strand RNA could be identified in supernatants intermittently. CONCLUSION: HCV may exist in the cultured cell line for a longer period and reproduce in and secrete out of the cells. This will offer a new cell model for studying the molecular biology and immunology of HCV.

Cell Transformation, Viral↗

PubMed1999

Identification of proteins in complexes by solid-phase microextraction/multistep elution/capillary electrophoresis/tandem mass spectrometry.

A method to directly identify proteins in complex mixtures by solid-phase microextraction (micro-SPE)/multistep elution/capillary electrophoresis (CE)/tandem mass spectrometry (MS/MS) is described. A sheathless liquid-metal junction interface is used to interface CE and electrospray ionization MS/MS. A subfemtomole detection limit is achieved for protein identification through database searching using MS/MS data. The SPE serves as a semiseparation dimension using an organic-phase step-elution gradient in combination with the second separation dimension for increased resolving power of complex peptide mixtures. This approach improves the concentration detection limit for CE and allows more proteins in complex mixtures to be identified. A 75-protein complex from yeast ribosome is analyzed using this method and 80-90% of the proteins in the complex can be identified by searching the database using the MS/MS data from a complete analysis. This multidimensional CE/MS/MS methodology provides an alternative to multidimensional liquid chromatography/MS/MS for direct identification of small amounts of protein in mixtures.

Electrophoresis, Capillary↗

PubMed1999

Bicyclic tripeptide mimetics with reverse turn inducing properties.

Analogues of the hypertensive octapeptide angiotensin II, comprising novel constrained 5,8-bicyclic and 5,9-bicyclic tripeptide units adopting nonclassical beta-turn geometries, as deduced from theoretical conformational analysis, have been synthesized. Spontanous bicyclization upon acid-catalyzed deprotection of a model peptide, encompassing a protected omega-formyl alpha-amino acid in position 5 and cysteine residues in positions 3 and 7, revealed a strong preference for bicyclization toward the C-terminus. The bicyclic thiazolidine related angiotensin II analogues synthesized exhibited no affinity for the angiotensin II AT1 receptor.

Angiotensin II↗

PubMed1999

Involvement of lipid mediators on cytokine signaling and induction of secretory phospholipase A2 in immortalized astrocytes (DITNC).

Our previous studies demonstrated the ability of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin 1beta (IL-1beta), to stimulate NFkappaB/DNA binding and synthesis of secretory phospholipase A2 (sPLA2) in immortalized astrocytes (DITNC). In this study, we examined possible involvement of lipid mediators in the cytokine action. Using [14C]serine to label sphingomyelin and ceramide in these cells, subsequent exposure of cells to cytokines did not result in alteration of sphingomyelin/ceramide ratio. Furthermore, neither exogenous sphingomyelinase nor cell-permeable ceramides could stimulate NFkappaB/DNA binding. On the other hand, C-2 ceramide (0.3 microM) as well as other lipid mediators, such as lysophosphatidylcholine and arachidonic acid, were able to elicit a small increase in sPLA2 and potentiate the induction of sPLA2 by TNF-alpha. When DITNC cells were prelabeled with [32P]Pi, an increase in labeled phosphatidic acid (PA) was observed on treatment of cells with IL-1beta (200 U/mL). However, despite the ability of phorbol myristate acetate (PMA) to stimulate phospholipase D (PLD) and synthesis of phosphatidylethanol (PEt) in these cells, PLD activity was not affected by IL-1beta. With the [32P]labeled cells, however, PA-phosphohydrolase inhibitors, such as chlorpromazine and propranolol, could elicit large increases in labeled PA, indicating active PA metabolism in these cells. Cytokines also caused an increase in levels of diacylglycerol (DG) in these cells, although the source of this lipid pool is presently not understood. Taken together, these results provide evidence for the participation of PA and DG in cytokine signaling activity. Furthermore, although cytokines did not cause the release of ceramide, lipid mediators, such as lysophospholipids, and AA could modulate cytokine-mediated induction of sPLA2 in astrocytes.

Animals↗

PubMed1999

Comparison of estrogen receptor alpha and beta subtypes based on comparative molecular field analysis (CoMFA).

A substantial body of evidence indicates that both humans and wildlife suffer adverse health effects from exposure to environmental chemicals that are capable of interacting with the endocrine system. The recent cloning of the estrogen receptor beta subtype (ER-beta) suggests that the selective effects of estrogenic compounds may arise in part by the control of different subsets of estrogen-responsive promoters by the two ER subtypes, ER-alpha and ER-beta. In order to identify the structural prerequisites for ligand-ER binding and to discriminate ER-alpha and ER-beta in terms of their ligand-binding specificities, Comparative Molecular Field Analysis (CoMFA) was employed to construct a three-dimensional Quantitative Structure-Activity Relationship (3D-QSAR) model on a data set of 31 structurally-diverse compounds for which competitive binding affinities have been measured against both ER-alpha and ER-beta. Structural alignment of the molecules in CoMFA was achieved by maximizing overlap of their steric and electrostatic fields using the Steric and Electrostatic ALignment (SEAL) algorithm. The final CoMFA models, generated by correlating the calculated 3D steric and electrostatic fields with the experimentally observed binding affinities using partial least-squares (PLS) regression, exhibited excellent self-consistency (r2 > 0.99) as well as high internal predictive ability (q2 > 0.65) based on cross-validation. CoMFA-predicted values of RBA for a test set of compounds outside of the training set were consistent with experimental observations. These CoMFA models can serve as guides for the rational design of ER ligands that possess preferential binding affinities for either ER-alpha or ER-beta. These models can also prove useful in risk assessment programs to identify real or suspected EDCs.

Algorithms↗

PubMed1999

Progesterone inhibits estrogen-induced cyclin D1 and cdk4 nuclear translocation, cyclin E- and cyclin A-cdk2 kinase activation, and cell proliferation in uterine epithelial cells in mice.

The response of the uterine epithelium to female sex steroid hormones provides an excellent model to study cell proliferation in vivo since both stimulation and inhibition of cell proliferation can be studied. Thus, when administered to ovariectomized adult mice 17beta-estradiol (E2) stimulates a synchronized wave of DNA synthesis and cell division in the epithelial cells, while pretreatment with progesterone (P4) completely inhibits this E2-induced cell proliferation. Using a simple method to isolate the uterine epithelium with high purity, we have shown that E2 treatment induces a relocalization of cyclin D1 and, to a lesser extent, cdk4 from the cytoplasm into the nucleus and results in the orderly activation of cyclin E- and cyclin A-cdk2 kinases and hyperphosphorylation of pRb and p107. P4 pretreatment did not alter overall levels of cyclin D1, cdk4, or cdk6 nor their associated kinase activities but instead inhibited the E2-induced nuclear localization of cyclin D1 to below the control level and, to a lesser extent, nuclear cdk4 levels, with a consequent inhibition of pRb and p107 phosphorylation. In addition, it abrogated E2-induced cyclin E-cdk2 activation by dephosphorylation of cdk2, followed by inhibition of cyclin A expression and consequently of cyclin A-cdk2 kinase activity and further inhibition of phosphorylation of pRb and p107. P4 is used therapeutically to oppose the effect of E2 during hormone replacement therapy and in the treatment of uterine adenocarcinoma. This study showing a novel mechanism of cell cycle inhibition by P4 may provide the basis for the development of new antiestrogens.

Animals↗