Biomedical subjects

J X Chen

Publications and source records attributed to J X Chen.

At least 37 records · Page 2Linked to original sources

PubMed1996

Using UvrABC nuclease to detect 7,12-dimethylbenz[a]anthracene anti-diol epoxide-DNA binding specificity in the mouse H-ras gene.

DNA fragments modified with chemically synthesized 7,12-dimethylbenz[a]anthracene anti-diol epoxide (anti-DMBADE) are sensitive to UvrABC nuclease incision. The incisions occur mainly 7 bases 5' and 4 bases 3' of an anti-DMBADE-modified adenine or guanine residue, and the kinetics of incision at different sequences in a DNA fragment are the same. These results indicate that UvrABC incision on anti-DMBADE-DNA adducts is independent of DNA sequences and is quantitative, the same as on syn-DMBADE-DNA adducts. This method was used to analyze the anti-DMBADE-DNA binding spectrum in the exon 2 region of the mouse H-ras gene, and it was found that anti-DMBADE binds to the two adenine residues at codon 61 of the H-ras gene with an average affinity. Previously, we have demonstrated that syn-DMBADE binds strongly to the adenines at codon 61 of H-ras; these results together suggest that the oncogenic mutation in H-ras may be induced by anti- and syn-DMBADE-DNA adducts.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1995

The receptor for advanced glycation end products (RAGE) is a cellular binding site for amphoterin. Mediation of neurite outgrowth and co-expression of rage and amphoterin in the developing nervous system.

The receptor for advanced glycation end products (RAGE), a newly-identified member of the immunoglobulin superfamily, mediates interactions of advanced glycation end product (AGE)-modified proteins with endothelium and other cell types. Survey of normal tissues demonstrated RAGE expression in situations in which accumulation of AGEs would be unexpected, leading to the hypothesis that under physiologic circumstances, RAGE might mediate interaction with ligands distinct from AGEs. Sequential chromatography of bovine lung extract identified polypeptides with M(r) values of approximately 12,000 (p12) and approximately 23,000 (p23) which bound RAGE. NH2-terminal and internal protein sequence data for p23 matched that reported previously for amphoterin. Amphoterin purified from rat brain or recombinant rat amphoterin bound to purified sRAGE in a saturable and dose-dependent manner, blocked by anti-RAGE IgG or a soluble form of RAGE (sRAGE). Cultured embryonic rat neurons, which express RAGE, displayed dose-dependent binding of 125I-amphoterin which was prevented by blockade of RAGE using antibody to the receptor or excess soluble receptor (sRAGE). A functional correlate of RAGE-amphoterin interaction was inhibition by anti-RAGE F(ab')2 and sRAGE of neurite formation by cortical neurons specifically on amphoterin-coated substrates. Consistent with a potential role for RAGE-amphoterin interaction in development, amphoterin and RAGE mRNA/antigen were co-localized in developing rat brain. These data indicate that RAGE has physiologically relevant ligands distinct from AGEs which are likely, via their interaction with the receptor, to participate in physiologic processes outside of the context of diabetes and accumulation of AGEs.

Animals↗

PubMed1995

Hypoxia and modification of the endothelium: implications for regulation of vascular homeostatic properties.

Hypoxia is a common denominator of ischemic microenvironments. Endothelium subjected to oxygen deprivation maintains cell viability and basic biosynthetic mechanisms, but displays multiple changes in properties relevant to vascular homeostasis, including suppression of the anticoagulant cofactor thrombomodulin, decreased barrier function, and generation of proinflammatory cytokines. Diminished intracellular cAMP during the period of hypoxia and lowered nitric oxide/cGMP in the subsequent reperfusion period are proposed as fundamental mechanisms driving vascular dysfunction impacting on coagulation, permeability, vasomotor tone and leukocyte adhesivity. The period of organ preservation for transplantation, recognized to be associated with hypoxia, primes mechanisms leading to subsequent vascular dysfunction which can be ameliorated by buttressing cAMP and nitric oxide/cGMP intra- and intercellular second messenger systems. A mechanism likely to contribute to hypoxia-mediated generation of cytokines, such as interleukin 6, is activation of the transcription factor NF-IL-6, which occurs in oxygen deprivation. These data indicate that study of cellular mechanisms of endothelial perturbation in hypoxia is likely to provide insights ultimately applicable to ischemia-induced vascular damage.

Animals↗

PubMed1995

Advanced glycation endproducts interacting with their endothelial receptor induce expression of vascular cell adhesion molecule-1 (VCAM-1) in cultured human endothelial cells and in mice. A potential mechanism for the accelerated vasculopathy of diabetes.

Vascular cell adhesion molecule-1 (VCAM-1), an inducible cell-cell recognition protein on the endothelial cell surface (EC), has been associated with early stages of atherosclerosis. In view of the accelerated vascular disease observed in patients with diabetes, and the enhanced expression of VCAM-1 in diabetic rabbits, we examined whether irreversible advanced glycation endproducts (AGEs), could mediate VCAM-1 expression by interacting with their endothelial cell receptor (receptor for AGE, RAGE). Exposure of cultured human ECs to AGEs induced expression of VCAM-1, increased adhesivity of the monolayer for Molt-4 cells, and was associated with increased levels of VCAM-1 transcripts. The inhibitory effect of anti-RAGE IgG, a truncated form of the receptor (soluble RAGE) or N-acetylcysteine on VCAM-1 expression indicated that AGE-RAGE-induced oxidant stress was central to VCAM-1 induction. Electrophoretic mobility shift assays on nuclear extracts from AGE-treated ECs showed induction of specific DNA binding activity for NF-kB in the VCAM-1 promoter, which was blocked by anti-RAGE IgG or N-acetylcysteine. Soluble VCAM-1 antigen was elevated in human diabetic plasma. These data are consistent with the hypothesis that AGE-RAGE interaction induces expression of VCAM-1 which can prime diabetic vasculature for enhanced interaction with circulating monocytes.

Animals↗

PubMed1995

[Therapy of cantharides extract for perennial allergic rhinitis and its effect on total IgE in serum].

The therapy of 10% Cantharides extract in treating 50 cases of perennial allergic rhinitis (PAR) was studied. The extract was plastered and blistered on Dazhui, Neiguan point. It was observed by nasal mucosa provocative test, cells in nasal secretion test and serum total IgE test. The results showed that its effective rate was 88%, the allergic nasal mucosa provocative test of treated group alleviated obviously after the treatment (P < 0.01), the number of eosinophil and basophil in nasal secretion decreased (P < 0.01, P < 0.05); and the serum total IgE also reduced significantly (P < 0.01).

Acupuncture Points↗

PubMed1995

Effects of gypenosides on mouse splenic lymphocyte transformation and DNA polymerase II activity in vitro.

AIM: To study the effects of gypenosides (Gyp) on lymphocyte transformation and DNA polymerase II activity. METHODS: Lymphocyte transformation response was induced by concanavalin A and lipopolysaccharides respectively. The activity of DNA polymerase II and DNA synthesis were assayed with TTP and [3H]TdR incorporation respectively in mixed lymphocyte culture test. RESULTS: Gyp 2.5-20 mg L-1 enhanced splenic T- and B- cell transformation, increased the DNA synthesis and potentiated the activity of DNA polymerase II. However, Gyp > 40 mg L-1 showed contrary effects. CONCLUSION: Gyp regulated lymphocyte transformation and DNA synthesis by regulating DNA polymerase II activity.

Animals↗

PubMed1995

[Preliminary study on pathophysiology of liver-qi deficiency syndrome].

The authors advocate a program for diagnosing Liver-Qi Deficiency Syndrome (LQDS) based on the TCM theory and clinical practice. Through investigation, LQDS was found to be widely existed as latent period or as external manifestation, which occupied 18.85% in Qi Deficiency Syndrome. The subjects were divided into four groups including normal group, Spleen-Qi Deficiency Syndrome (SQDS) group, LQDS with Liver diseases (LD) and LQDS with non-Liver diseases (NLD) group. In order to explore the essence, the simultaneous determinations were done on lactate dehydrogenase (LDH) and its isoenzyme, dopamine beta-hydroxylase (D beta H), trace element Zn and Cu, and other serological indexes such as GPT, TP, Alb, A/G, etc. The results were, the content of LDH and trace element Zn in both LQDS-NLD and SQDS were significantly lower than that of normal group. D beta H reflecting sympathetic nerve function in LQDS-NLD was significantly higher than that of both normal and SQDS group; comparing LQDS-LD and LQDS-NLD group, the content of GPT, LDH, LDH5 and trace element Cu in former was significantly higher than that of the latter, but the content of TP, Alb, A/G, D beta H and Zn in former was remarkably lower than that of the latter. In order to avoid confusion, in studying this syndrome, one should distinguish LD and NLD.

Adult↗

PubMed1994

Activation of early response genes and cell proliferation by human interleukin-3, granulocyte-macrophage colony-stimulating factor, and interleukin-5 receptors: comparison with human interleukin-4 receptor signaling.

Interleukin (IL)-3, granulocyte-macrophage colony-stimulating factor, and IL-5 receptors (IL-3R, GMR, and IL-5R) are composed of the alpha chain specific to each and the common beta chain, and both the alpha and beta subunits are members of the cytokine receptor superfamily. We previously showed that the high-affinity human GMR reconstituted by cotransfecting the alpha and beta chain cDNA clones transduces signals in response to hGM-CSF to activate transcription of c-fos, c-jun, and c-myc proto-oncogenes in mouse proB cell line BA/F3 or in mouse fibroblast NIH3T3 cells. These results indicated that molecules, such as tyrosine kinase, unique to hematopoietic cells are not essential to transduce signals. In this study, the function of the alpha subunit of GMR was compared with those of IL-3R and IL-5R by cotransfecting human cDNAs encoding the alpha subunit of IL-3R or IL-5R and the common beta subunit into BA/F3 or NIH3T3 cells. We found that the reconstituted human IL-3R, in response to hIL-3, transduced signals to activate transcription of c-fos promoter and induced DNA synthesis in both types of cells in a manner similar to hGMR. Likewise, hIL-5 activates c-fos promoter in transfected NIH3T3 cells expressing hIL-5R. These results indicated that the alpha subunits of IL-3R and IL-5R have properties similar to those of the GMR alpha subunit. In contrast, transfected human IL-4 receptor (hIL-4R) cDNA, which weakly activated c-fos promoter and induced DNA synthesis in BA/F3 cells, failed to elicit these activities in NIH3T3 cells in response to hIL-4.(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗

PubMed1994

[The role of endotoxin in the bronchial hyperreactivity formation].

Endotoxin was as a pathogen to investigate its effects on bronchial hyperreactivity formation. The latent periods of guinea pigs inhaled histamine and PD2 value of isoproterenol were markedly decreased 4 days after the intraperitoneal injection of endotoxin 1 mg/kg, meanwhile PD2 value of histamine and histamine levels of lung tissue and plasma were increased significantly. These results indicate that endotoxin is a very important factor in the infection induced bronchial hyperreactivity.

Animals↗

PubMed1993

Reconstituted human granulocyte-macrophage colony-stimulating factor receptor transduces growth-promoting signals in mouse NIH 3T3 cells: comparison with signalling in BA/F3 pro-B cells.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) plays a critical role in growth and differentiation of myeloid cells. We previously reconstituted high-affinity human GM-CSF receptor (hGM-CSFR) in a pro-B cell line, BA/F3, by cotransfecting alpha- and beta-chain cDNA clones and showed that the reconstituted receptor could transduce growth-promoting signals. The high-affinity hGM-CSFR was also reconstituted in mouse NIH 3T3 cells, but its ability to transduce signals in fibroblasts remained undetermined. In the present study, we further characterized signal transduction by the reconstituted hGM-CSFR in both NIH 3T3 cells and BA/F3 cells. We found that the reconstituted hGM-CSFR transduces signals in NIH 3T3 fibroblasts and BA/F3 cells in response to hGM-CSF to activate transcription of the c-fos, c-jun, and c-myc proto-oncogenes. hGM-CSF also induces protein tyrosine phosphorylation and DNA synthesis in both cell types. These results indicated that hGM-CSFR is functional in fibroblasts, that signal transduction via hGM-CSFR in fibroblasts involves tyrosine kinase(s), and that association of hGM-CSFR with a factor(s) specific to hematopoietic cell lineage is not essential to transduce growth-promoting signals.

3T3 Cells↗

PubMed1993

EDAP piezoelectric shock wave lithotripsy for gallbladder stones.

EDAP piezoelectric shock wave lithotripsy combined with oral ursodeoxycolic acid dissolution of stones was used to treat 1055 patients with gallbladder stones. 926 of them (87.8%) were followed up for more than 1 year. The patients were divided into two groups: Group I, 637 patients with functioning gallbladders containing one radiolucent stone less than or equal to 20 mm in diameter or 2 to 3 stones each less than or equal to 12 mm, and Group II: 289 patients with stones exceeding the above criteria. The stone fragmentation rate was 96.2% and 94.1% respectively in Group I and in Group II. Gallbladder stones disappeared in 18.5%, 35.0%, 46.2% and 52.4% of the patients in Group I in 1, 3, 6, and 12 months after treatment and 7.3%, 11.4%, 20.1%, and 27.7% in Group II. The treatment was more effective for solitary stones less than or equal to 20 mm in diameter. No serious complications were noted. The midterm curative effect was satisfactory. Further study is required to raise the curative effect and prevent stone recurrence.

Adult↗

PubMed1992

Transferrin subtypes in 11 south China minority populations.

Transferrin subtypes were determined by isoelectric focussing (IEF) in a total of 2,121 individuals from 11 South China minority populations. The C1, C2 and DCHI alleles were present in all the populations; B alleles were lacking, C4 was found in 3 populations and C3 in 6. C2 and C4 allele frequencies are notable in these minority groups. The frequency of the C2 allele was higher (0.25-0.38) than that of Han Chinese (0.18-0.25). In Bai the C2 frequency was as high as 0.38. The C4 allele was present at a low frequency (less than 0.01), which suggests that this allele probably existed in the ancestral Mongoloid population at a low frequency and increased in frequency in Amerindians due to genetic drift or other factors.

Alleles↗

PubMed1991

Mutational analysis of the sequence encoding ICP0 from herpes simplex virus type 1.

In-frame codon insertion and deletion mutants were constructed in a plasmid containing the sequence that encodes ICP0, a transcriptional activator of herpes simplex virus type 1 (HSV-1). The effect of these mutations was analyzed in a transient expression assay using the promoters for, the IE-0 gene (an immediate early (alpha) gene), the thymidine kinase gene (an early (beta) gene), and the glycoprotein C gene (a late (gamma) gene) fused to reporter cassettes that encoded either beta-galactosidase or chloramphenicol acetyl transferase. Assays were performed in the presence or absence of a plasmid encoding ICP4, the major regulatory protein of HSV-1. Our results demonstrate that ICP0-mediated transactivation varied depending on the position of the insertion in the gene. One region of this protein was consistently shown to be required for full activation of each promoter examined either in the presence or in the absence of ICP4. This region overlaps with a cysteine-rich region and coincides with a transactivator domain identified in another extensive mutational analysis of this sequence. Analysis of the deletion mutants generated in this study demonstrated that the carboxy-terminal regions were required for activation in certain circumstances and that this varied depending on the promoter being assayed and the cell type in which the analysis was performed.

Amino Acid Sequence↗

PubMed1991

Isolation and characterization of a functional cDNA encoding ICP0 from herpes simplex virus type 1.

The IE-0 gene of herpes simplex virus type 1 (HSV-1) contains two introns and encodes ICP0, a powerful transcriptional activator. We have isolated a cDNA clone that encodes ICP0 from a lambda gt10 cDNA library constructed from RNAs made from HSV-1-infected HeLa cells. DNA sequence analysis of this clone confirmed the predicted intron/exon boundaries (L. J. Perry, F. J. Rixon, R. D. Everett, M. C. Frame, and D. J. McGeoch, J. Gen. Virol. 67:2365-2380, 1986). Following transfection, a plasmid containing the cDNA copy of IE-0 directed the synthesis of ICP0, which was appropriately compartmentalized and distributed in the nucleus, as revealed by immunofluorescence. A transient expression assay was used to demonstrate that this cDNA copy retained the ability to transactivate the HSV-1 promoters for the IE-0 gene (an immediate-early gene), the thymidine kinase gene (an early gene), and the glycoprotein C gene (a late gene). The product of this cDNA clone cooperated with ICP4 to activate expression from the thymidine kinase gene promoter in a synergistic manner. The availability of a functional cDNA copy encoding ICP0 provides the opportunity to express this protein in vector systems that do not recognize eucaryotic donor and acceptor splicing signals to overexpress ICP0.

Base Sequence↗

PubMed1991

[Studies on pyridonecarboxylic acids as antibacterial agents. X. Synthesis and structure-activity relationships of 1, 7-disubstituted-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acids].

A series of pyridonecarboxylic acids were prepared. These compounds have different groups including substituted benzenes, furans and isoxazles at the 1-position, or different substituted amino groups at the 7-position. The in vitro antibacterial potencies of these compounds against E. coli. and S. aureus were tested, and structure-activity relationships were discussed.

4-Quinolones↗

PubMed1990

The CDC4 gene product is associated with the yeast nuclear skeleton.

The CDC4 gene product of Saccharomyces cerevisiae is required at the late G1/S phase boundary of the cell cycle. In an attempt to better understand the function of CDC4, we performed experiments to localize this protein in the yeast cell. Using antisera, directed against a TrpE-CDC4 fusion protein, to analyze immuno-blots of different subcellular fractions from yeast, we demonstrated that the CDC4 gene product localizes in the nucleus by two different biochemical preparations of the yeast nucleoskeletal proteins. Immunofluorescence microscopy further confirmed its nuclear localization. These data support a model that includes the CDC4 gene product as a component of the yeast nuclear skeleton. The significance of this association in relationship to the biological role of CDC4 is discussed.

Cell Cycle↗

PubMed1990

Reactivation of latent herpes simplex virus by adenovirus recombinants encoding mutant IE-0 gene products.

We have previously shown that adenovirus recombinants expressing functional ICP0 reactivate latent herpes simplex virus type 2 (HSV-2) in an in vitro latency system. This study demonstrated that ICP0, independent of other HSV gene products, is sufficient to reactivate latent HSV-2 in this in vitro system. To assess the effects of defined mutations in the sequence encoding ICP0 (IE-0) on reactivation, seven in-frame insertion and three in-frame deletion mutants were moved into an adenovirus expression vector. Each recombinant directed the synthesis of stable ICP0 of the correct size. The transactivation activity of the mutated sequences in these recombinants was similar to that when they were tested in plasmids. When these recombinants were examined for their ability to reactivate in the in vitro latency system, mutants with dramatic defects in transactivation (Ad-0/125, Ad-0/89, Ad-0/2/7, and Ad-0/88/93) were unable to reactivate latent HSV-2 independent of the multiplicity of infection. An exception to this correlation was the finding that Ad-0/89, which transactivated poorly, was able to reactivate latent virus after prolonged incubation whereas other transactivation-deficient mutants could not. Moreover, the presence of ICP4 did not compensate for the inability of any of the recombinants tested to reactivate HSV-2. These results show that (i) the transactivation domains of ICP0 are also used in reactivation, (ii) the presence of another essential HSV regulatory protein ICP4 does not alter the pattern of reactivation by ICP0, and (iii) mutations in some regions of IE-0 previously shown to affect viral growth and plaque formation did not alter its ability to reactivate in this in vitro system.

Adenoviruses, Human↗

PubMed1990

Extracorporeal shock wave lithotripsy. Experience in treating 245 patients with gallbladder stones.

An EDAP LT-01 lithotripter was used to treat 245 patients with functioning gallbladders containing one to three radiolucent stones of less than 20 mm in diameter. Ursodeoxycholic acid was administrated as adjuvant litholytic therapy. The gallbladder stones disintegrated in 98.8% of patients and disappeared completely in 21.2% within 1 month after lithotripsy, in 26.5% within 2 months, in 33.9, 40, 46.5, 48.6 and 53.9% within 3, 4, 6, 9, and 12 months, respectively. Adverse effects after lithotripsy were dull abdominal pain (49.4%), biliary colic (13.1%), jaundice (1.2%), and pancreatitis (0.4%). Extracorporeal shock wave lithotripsy combined with litholytic therapy is a non-invasive, painless, safe, and effective treatment in selected patients. Patients with solitary radiolucent stone less than 20 mm in diameter are considered candidates for extracorporeal shock wave lithotripsy (ESWL). The key to success of ESWL lies in the strict selection of patients, careful monitoring throughout the lithotriptic procedure, and enough litholytic therapy. The disadvantages of this method include strict selection of patients and high costs, poor curative effect, and recurrence of stones (11.4% of patients).

Adult↗