Biomedical subjects

X Fang

Publications and source records attributed to X Fang.

At least 109 records · Page 6Linked to original sources

PubMed1999

13-(S)-hydroxyoctadecadienoic acid (13-HODE) incorporation and conversion to novel products by endothelial cells.

13(S)-Hydroxy-[12,13-3H]octadecadienoic acid (13-HODE), a linoleic acid oxidation product that has vasoactive properties, was rapidly taken up by bovine aortic endothelial cells. Most of the 13-HODE was incorporated into phosphatidylcholine, and 80% was present in the sn -2 position. The amount of 13-HODE retained in the cells gradually decreased, and radiolabeled metabolites with shorter reverse-phase high-performance liquid chromatography retention times (RT) than 13-HODE accumulated in the extracellular fluid. The three major metabolites were identified by gas chromatography combined with mass spectrometry as 11-hydroxyhexadecadienoic acid (11-OH-16:2), 9-hydroxytetradecadienoic acid (9-OH-14:2), and 7-hydroxydodecadienoic acid (7-OH-12:2). Most of the radioactivity contained in the cell lipids remained as 13-HODE. However, some 11-OH-16:2 and several unidentified products with longer RT than 13-HODE were detected in the cell lipids. Normal human skin fibroblasts also converted 13-HODE to the three major chain-shortened metabolites, but Zellweger syndrome fibroblasts produced only a very small amount of 11-OH-16:2. Therefore, the chain-shortened products probably are formed primarily by peroxisomal beta-oxidation. These findings suggest that peroxisomal beta-oxidation may constitute a mechanism for the inactivation and removal of 13-HODE from the vascular wall. Because this is a gradual process, some 13-HODE that is initially incorporated remains in endothelial phospholipids, especially phosphatidylcholine. This may be the cause of some of the functional perturbations produced by 13-HODE in the vascular wall.

Animals↗

PubMed1999

Sweat gland adenoma with predominant myoepithelial differentiated features: case report and immunohistochemical study.

A 56-year-old man presented with a subcutaneous mass adjacent to the sternoclavicular joint region, which had predominant spindle-shaped myoepithelial cells and a small number of tubular or trabecular epithelial cells that resembled eccrine differentiation under a light microscope. Immunohistochemical studies showed positive staining for muscle-specific actin and vimentin in the myoepithelial cells, but staining was negative for S-100 protein and keratin. The tubular and trabecular epithelial cells stained positively for keratin, EMA and CEA. We believe that this rare tumor had the potential for biphasic differentiation and should be differentiated from other biphasic differentiated or mixed tumors in this site. Immunohistochemical staining was useful for diagnosis and differential diagnosis.

Adenoma↗

PubMed1999

Development and application of a minimal-adenoviral vector system for gene therapy of hemophilia A.

To achieve efficient delivery and sustained expression of the human factor VIII cDNA in vivo, a minimal-adenoviral (mini-Ad) vector system was developed. The system is composed of a mini-Ad vector with essential cis-elements (less than 1 kb) of the viral genome, an E1-deleted ancillary Ad with packaging attenuation, and an E1-complementing production cell line. Based on this system, MiniAdFVIII was generated to deliver a 27 kb expression cassette consisting of a full-length human factor VIII cDNA flanked by human albumin promoter and genomic sequences. The MiniAdFVIII vector mediated expression of functional human factor VIII in HepG2 and 293 cells. A single-dose intravenous injection of 10(11) viral particles in hemophilic mice of MiniAdFVIII produced a sustained high-level expression of human factor VIII (at 100-800 ng/ml up to 369 days) which corrected the FVIII-deficient phenotype. Safety studies of MiniAdFVIII showed that there were no significant toxic effects in mice and dogs after single intravessel doses of up to 3 x 10(11) and 6 x 10(12) viral particles, respectively. Studies for developing the MiniAdFVIII vector with a site-specific integration mechanism and progress in the development of a human factor VIII-tolerized mouse model for pre-clinical studies of MiniAdFVIII are reported. Further pre-clinical studies and product development of MiniAdFVIII for clinical trials are also discussed.

Adenoviridae↗

PubMed1999

Overexpression of edg-2/vzg-1 induces apoptosis and anoikis in ovarian cancer cells in a lysophosphatidic acid-independent manner.

Lysophosphatidic acid (LPA) is one of the major growth factors in ascites from ovarian cancer patients and appears to play an important role in proliferation, survival, and invasion of ovarian cancer cells. Recently, several groups have shown that Edg-2, which belongs to the G-protein coupled receptor family, is a functional LPA receptor. Northern blot analysis showed that most ovarian cancer cell lines express Edg-2. Edg-2 expression was especially high in the cisplatin-resistant and slowly proliferating 2780cp cell line and was almost absent from the cisplatin-sensitive and rapidly proliferating A2780 cell line. We thus assessed whether Edg-2 could contribute to changes in cell viability, cell proliferation, or cisplatin resistance. Stable overexpression of Edg-2 in A2780 cells induced an exogenous LPA-independent decrease in proliferation but did not alter cisplatin sensitivity. The LPA-independent decrease in growth rate induced by overexpression of Edg-2 could be explained, at least in part, by Edg-2-induced apoptosis rather than by effects on cell cycle progression. In agreement with the results in stably transfected A2780 cells, transient expression of Edg-2 in Jurkat T cells also induced apoptosis. When cells were separated from the extracellular matrix, they underwent a specialized form of apoptosis called anoikis, which is particularly important in survival of cells in the circulation during metastasis. A2780 cells engineered to overexpress Edg-2 were particularly sensitive to anoikis. These observations suggest that Edg-2 may be a negative regulator for ovarian epithelial cell growth and metastasis.

Animals↗

PubMed1999

[Study on in vitro cytokines levels induced from peripheral mononuclear cells in patients with endometriosis].

OBJECTIVE: To study the changes and significance of interleukin-6 (IL-6), interleukin-8(IL-8), tumor necrosis factor-alpha (TNF-alpha) and nitric oxide (NO) levels in vitro cultured system of peripheral mononuclear cells in patient with endometriosis(Em). METHODS: Peripheral blood mononuclear cells from 31 cases of endometriosis, classified into mild group (stage I and II, n = 11), and severe group (stage III and IV, n = 20) according to the Revised American Fertility society criteria 1985, and 15 normal controls were separated and induced by lipopolysaccharide and phytohemagglutinin, followed by 48 hour incubation in vitro, then the supernatant were collected. The levels of IL-6, IL-8 and TNF-alpha were measured by enzyme linked immunosorbent assays, the concentrations of NO, expressed by nitrite and nitrate (NO2-/NO3-) content were measured by Griess methods. RESULTS: The concentrations of IL-6, IL-8, TNF-alpha and NO were significantly higher in both mild and severe Em groups than those in controls (P < 0.01). No differences between the mild and severe Em groups was seen. There were strong positive correlation between the levels of IL-6 and IL-8, TNF-alpha and NO in patients with endometriosis (P < 0.01). CONCLUSIONS: The immune function of peripheral mononuclear cell in patients with endometriosis was disordered. It may activate peripheral mononuclear cells to produce high levels of IL-6, IL-8, TNF-alpha and NO, which may take part in the pathogenesis of endometriosis.

Endometriosis↗

PubMed1999

[Influence of roxithromycin combined with fleroxacin on bacterial biofilm induced by Pseudomonas aeruginosa].

OBJECTIVE: To investigate the influence of roxithromycin (RXM) on the production of glycocalyx (GLX) and the synergic effect of RXM and fleroxacin (FLRX) on P. Aeruginosa biofilms. METHODS: Bacterial biofilm (BF) was established and was influenced by RXM and FLRX with different concentrations. The samples were detected with scanning electron microscope and by a rapid method after BF was stained with AgNO3 solution. The synergism of antibacterial activities of RXM and FLRX to P. Aeruginosa was studied by computer image analysis and MTT method. RESULTS: GLX production was reduced significantly by both 1/16 MIC and 1/4 MIC RXM (P < 0.01). 1/16 MIC and 1/4 MIC RXM showed no bactericidal activities to P. Aeruginosa in biofilms, while viable counts in biofilms almost had no difference. However, RXM could enhance the bactericidal activity of FLRX to P. Aeruginosa in biofilms. When FLRX of different concentrations was combined with 1/16 MIC and 1/4 MIC RXM respectively, the difference of the stained BF was counted up by computer image analysis system with significance of P < 0.05 and the viable counts were reduced significantly (P < 0.05). The results was in accordance with SEM pictures. CONCLUSION: RXM has no direct bactericidal activities to P. Aeruginosa in biofilms, but it could inhibit GLX production. It can be considered that RXM could enhance antibacterial activities of FLRX by enhancing the permeability of FLRX into biofilms.

Anti-Bacterial Agents↗

PubMed1999

[Changes in blood coagulation affected by rifampicin administration].

OBJECTIVE: To study the characteristics of influence on coagulation by rifampicin (RFP) administration. METHODS: Seventy-three patients, ages between 10 and 65 years(mean age 30.3 years), with tuberculosis of neck lymphnode were treated with 2HRZS/10HRE. The prothrombin time, activity, fibrinogen, II: C, V: C, VII: C, IX: C and alanine aminotransferase concentration in each case were observed during the period of RFP administration. RESULTS: The prolongation of the PT and the reduction of the PA, FIB concentration in 48 cases were observed after 5-30 days following RFP administration. These changes depended on drug dosage and duration, especially the severe influence on coagulation were detected when the RFP were reused after the ALT normalized in seventh to tenth months. The ALT was (18 +/- 12) U/L in the tenth month, but the PT was (19.2 +/- 3.9) s and the FIB was (1.8 +/- 0.5) g/L respectively. CONCLUSIONS: Not only the coagulation factors II, VII, IX, X, but also I V, VI and VIII were affected by RFP. The coagulation test is more sensitive than ALT test in the evaluation of liver injury. RFP should be stopped when FIB less than 1 g/L in spite of ALT in normal range.

Adolescent↗

PubMed1999

[Antiviral action of combined use of rhizoma Polygoni cuspidati and radix Astragali on HSV-1 strain].

OBJECTIVE: The clinical action of combined use of Rhizoma Polygoni Cuspidati and Radix Astragali on HSV-1 was investigated with a view to developing a new antiviral drug. METHOD: The action was analyzed by way of plaque reduction assay and median-effect principle. RESULTS: In the HEp-2 cell system, if the combination ratio of Rhizoma Polygoni Cuspidati and Radix Astragali was 1(ED50):1(ED50) then, (1) In directly annihilating HSV-1 F strain, when the plaque reduction rate was 20%-80%, and the combination index was < 1.0, there was synergism. (2) In inhibiting the multiplication of HSV-1 F strain, when the plaque reduction rate was 20%-60%, and the combination index was < 1.0, there was also synergism. (3) In blockading HSV-1 F strain infection, when the plaque reduction rate was 20%-90% and the combination index was < 1.0, there was synergism. So this ratio of 1(ED50):1(ED50) should be the first choice for combination. CONCLUSION: The treatment index of the above two Chinese medicinal herbs equals 10(3), and the cytotoxicity is not potentiated, indicating that the combination is helpful as a virucide for HSV-1 F strain.

Antiviral Agents↗

PubMed1999

[Diagnosis and treatment of internal jugular phlebectasia (three cases report].

OBJECTIVE: To discuss the diagnosis and treatment of patients with rare abnormal veins: the internal jugular phlebectasia. METHODS: Three patients with swollen during straining or crying were diagnosed as internal jugular vein dilatation by ultra-sonography, DSA and MRI. Then an operation of envelopment of the right internal jugular vein with the sternocleidomastoid muscle was performed in two cases. In the third case, the bilateral internal jugular ectasia, the right internal jugular vein were resected and the left internal jugular vein was enveloped with the resected vein. RESULTS: These three patients were treated satisfactorily by operation, and no recurrence in the following two years. CONCLUSION: To those who want their internal jugular phlebectasia to be treated, the operation of envelopment of internal jugular vein with sternocleidomastoid muscle is a good method.

Adolescent↗

PubMed1999

[Separation of alkylphenols in oil field water by micellar electrokinetic chromatography].

The abundance of alkylphenols in the system of water, oil and rock is of great geochemistry significance. The analysis of alkylphenols in oil field water using micellar electrokinetic chromatography with UV detection is described. The different variables that affect separation were studied and optimized. The results show that better separation was obtained with the borate concentration of 47.5 mmol/L, the SDS concentration of 70.0 mmol/L, pH 9.15, separation current of 100 microA, capillary temperature 20 degrees C. The organic additive(beta-CD) could partly improve separation. Water sample was introduced into the capillary by pressure of 5 kPa for several seconds. Detection wavelength was 200 nm and reference wavelength at 350 nm for all experiments. For the oil field water sample, the reproducibility of directly injected oil field water after filtration through a membrane filter of 0.45 micron pore size was far from good and it's concentrations of alkylphenols were too low to be detected. Therefore, a method of separation and enrichment by a column packed with tributyl phosphate(TBP) extraction resin was applied for analysis of TZ4 oil field water. Qualitative analysis show that there are phenol, o-cresol, m-cresol and p-cresol in this water sample and phenol is the main component and it's quantity is more than other alkylphenols. It's recoveries from the oil field water were 91.5%-95.3%. The results were satisfactory.

Chromatography, Micellar Electrokinetic Capillary↗

PubMed1999

[Experimental studies on pharmacodynamic effect of Macleaya cordata].

The pharmacodynamic effect of Macleaya cordata was investigated in this study. The results showed that Macleaya cordata could improve liver function of acute hepatic injuries in rats caused by tetrachloromethan or galactoslmine. Macleaya cordata could lessen the level of serum LDH and mortality of rats, increase ratio of serum A/G, protect cellular membrane efectively and inhibit fibrosis in rats with chromic heptic injury caused by tetrachloromethane. Macleaya cordata still enhanced the function of T and B lymphocytes.

Albumins↗

PubMed1998

Adenoviral transgene expression of MMAC/PTEN in human glioma cells inhibits Akt activation and induces anoikis.

The MMAC/PTEN tumor suppressor gene encodes for a phosphatase that recently has been shown to have phosphotidylinositol phosphatase activity, implicating its possible involvement in phosphatidylinositol 3'-kinase-mediated signaling. To investigate possible alterations in growth factor-mediated signal transduction, an adenovirus containing MMAC/PTEN, Ad-MMAC, previously shown to inhibit growth and tumorigenicity in glioma cells, was used to acutely express the transgene. Human glioma cells infected with Ad-MMAC but not with control adenoviruses exhibited an inhibition of phosphorylation of both activating residues of Akt, Ser-473, and Thr-308, along with Akt's serine/threonine kinase activity, without significantly altering Akt expression. The effects of functional MMAC/PTEN expression were relatively specific, because members of several other growth factor-mediated signaling pathways showed no altered responses. The presence of MMAC/PTEN also inhibited phosphorylation of BAD, although no evidence of apoptosis in the in situ treated cells was observed. However, U251 glioma cells infected with Ad-MMAC were induced to undergo anoikis at a significantly higher rate than U251 cels treated with control viruses or mock infected with media. These results demonstrate that the acute administration of MMAC/PTEN results in the inhibition of Akt-mediated signaling, growth inhibition, and anoikis, implying that loss of MMAC/PTEN increases cellular proliferation and significantly augments a cell's survival potential during cellular processes that are associated with malignancy.

Adenoviridae↗

PubMed1998

14-Desoxy analogues of naltrindole and 7-spiroindanyloxymorphone: the role of the 14-hydroxy group at delta opioid receptors.

The 14-hydroxy group is known to increase the antagonist potency of mu-selective opioid ligands. To investigate the role of this group at the delta opioid receptor, the 14-desoxy analogues (7 and 9) of the delta-selective ligands, naltrindole (1, NTI) and spiroindanyloxymorphone (2, SIOM), have been synthesized and tested. The in vitro pharmacologic activities of 7 and 9 suggest that the 14-hydroxy group plays an important role in determining the delta selectivity and potency of NTI and SIOM.

Animals↗

PubMed1998

Overexpression of human superoxide dismutase inhibits oxidation of low-density lipoprotein by endothelial cells.

Oxidation of LDL in the subendothelial space has been proposed to play a key role in atherosclerosis. Endothelial cells produce superoxide anions (O2.-) and oxidize LDL in vitro; however, the role of O2.- in endothelial cell-induced LDL oxidation is unclear. Incubation of human LDL (200 microg/mL) with bovine aortic endothelial cells (BAECs) for 18 hours resulted in a 4-fold increase in LDL oxidation compared with cell-free incubation (22.5+/-1.1 versus 6.3+/-0.2 [mean+/-SEM] nmol malondialdehyde/mg LDL protein, respectively; P<0.05). Under similar conditions, incubation of LDL with porcine aortic endothelial cells resulted in a 5-fold increase in LDL oxidation. Inclusion of exogenous copper/zinc superoxide dismutase (Cu/ZnSOD, 100 microg/mL) in the medium reduced BAEC-induced LDL oxidation by 79%. To determine whether the intracellular SOD content can have a similar protective effect, BAECs were infected with adenoviral vectors containing cDNA for human Cu/ZnSOD (AdCu/ZnSOD) or manganese SOD (AdMnSOD). Adenoviral infection increased the content and activity of either Cu/ZnSOD or MnSOD in the cells and reduced cellular O2.- release by two thirds. When cells infected with AdCu/ZnSOD or AdMnSOD were incubated with LDL, formation of malondialdehyde was decreased by 77% and 32%, respectively. Two other indices of LDL oxidation, formation of conjugated dienes and increased LDL electrophoretic mobility, were similarly reduced by SOD transduction. These data suggest that production of O2.- contributes to endothelial cell-induced oxidation of LDL in vitro. Furthermore, adenovirus-mediated transfer of cDNA for human SOD, particularly Cu/ZnSOD, effectively reduces oxidation of LDL by endothelial cells.

Adenoviridae↗

PubMed1998

Activation of the ras-mitogen-activated protein kinase pathway and phosphorylation of ets-2 at position threonine 72 in human ovarian cancer cell lines.

The activation status of the ras pathway was studied in eight ovarian tumor cell lines. Three biochemical parameters indicative of ras activation were tested: (a) the ratio of the ras-GTP:ras-GDP complex; (b) the activity of mitogen-activated protein kinases p42/p44; and (c) ets-2 phosphorylation at position threonine 72, a mitogen-activated protein kinase phosphorylation site in vivo. Four of the ovarian tumor cell lines had an activated ras pathway by these three parameters, whereas only one of these contained a mutated ras gene. In addition, ras/ets-2 responsive genes such as the urokinase plasminogen activator (uPA) were activated in these four cell lines. Transient transfection assays indicated that the compound ets-AP1 oncogene responsive enhancer present in the uPA gene was the target of ras signaling in ovarian tumor cells and that the combination of activated ras and ets-2 could superactivate the uPA enhancer element. Coexpression of the dominant-negative ras-Asn17 cDNA gene abrogated activity of this uPA element in ovarian tumor cells. These data indicate that ets-2 is a nuclear target of ras action in ovarian tumor cell lines and that ras signaling pathways may be activated in ovarian cancer by mechanisms independent of direct genetic damage to ras genes.

Antineoplastic Agents↗

PubMed1998

Probing the active site of cytochrome P450 2B1: metabolism of 7-alkoxycoumarins by the wild type and five site-directed mutants.

A series of 7-alkoxycoumarins (chain length of 1-7 carbon atoms) was utilized as active site probes of purified Escherichia coli-expressed cytochrome P450 2B1 wild type and five site-directed mutants (I114V, F206L, V363A, V363L, and G478S). The production of 7-hydroxycoumarin, the O-dealkylation product, by the wild-type enzyme exhibited a rank order of C2 > C4 > C3 > C1 > C5 > C6 = C7. The pattern observed for the P450 I114V mutant was similar to that of the wild-type enzyme, whereas with F206L and G478S mutants, the rate of O-dealkylation was low with all the compounds. In contrast, with V363A, the highest rate of product formation was observed with 7-butoxycoumarin. The V363L mutant preferentially catalyzed the O-dealkylation of 7-methoxy- and 7-ethoxycoumarin, and a further increase in the length of the alkyl chain led to a marked decrease in product formation. The stoichiometry of 7-butoxycoumarin oxidation by V363L suggested that products other than 7-hydroxycoumarin were also formed. HPLC and GC-EIMS analyses revealed that P450 2B1 V363L produced 7-(3-hydroxybutoxy)coumarin and 7-(4-hydroxybutoxy)coumarin as major oxidation products, while the V363A mutant mainly catalyzed the O-dealkylation of 7-butoxycoumarin. Docking of alkoxycoumarins into the active site of a P450 2B1 homology model confirmed the importance of the studied residues in substrate dealkylation and explained the formation of novel 7-butoxycoumarin products by the V363L mutant.

7-Alkoxycoumarin O-Dealkylase↗

PubMed1998

Expression of p16 induces transcriptional downregulation of the RB gene.

The RB and p16(INK4A) tumor suppressor genes function in the same pathway of cell cycle control. Previous evidence indicates that the p16(INK4A) gene is transcriptionally repressed by the RB gene product, pRB. In this study using human ovarian cancer cell lines, we found that RB protein and mRNA were expressed at higher levels in cell lines lacking p16 than in those with normal p16. Since this suggests a potential role of p16 in regulating the cellular level of pRB, we studied the effect of wild-type p16(INK4A) on expression of the RB gene. Introduction of p16(INK4A), carried by an adenovirus vector, into p16-negative cell lines dramatically decreased expression of RB protein and mRNA. Nuclei run-off assays demonstrated that p16 expression induced transcriptional downregulation of the RB gene. These results indicate that expression of RB is inversely regulated by p16. The findings reveal a new dimension of pRB-p16 interaction and should have implications for p16(INK4A)-mediated gene therapy.

Adenoviridae↗

PubMed1998

Cell-specific regulation of transcription of the malic enzyme gene: characterization of cis-acting elements that modulate nuclear T3 receptor activity.

Stimulation of malic enzyme transcription by triiodothyronine (T3) is robust (> 60-fold) in chick embryo hepatocytes, weak (5-fold) in chick embryo fibroblasts that stably overexpress the nuclear T3 receptor-alpha, and still weaker (1-fold) in chick embryo fibroblasts which contain nuclear T3 receptor levels that are similar to those of chick embryo hepatocytes. Using DNase I hypersensitivity, functional transfection, and in vitro DNA-binding analyses, four cis-acting elements were identified in the malic enzyme 5'-flanking DNA that conferred differences in nuclear T3 receptor activity between chick embryo hepatocytes and chick embryo fibroblasts. These cell-specific regulatory elements are located at -3895/-3890, -3761/-3744, -3703/-3686, and -3474/-2715 bp and overlap with DNase I hypersensitive sites that are observed in chromatin of chick embryo hepatocytes. Each element enhances T3 responsiveness of the malic enzyme promoter in chick embryo hepatocytes but has no effect on T3 responsiveness in chick embryo fibroblasts. Three of the cell-specific regulatory elements flank a previously identified DNA fragment (-3889 to -3769 bp; Hodnett et al., Arch. Biochem. Biophys. 334, 309-324, 1996) that contains one major and four minor T3 response elements. The cell-specific regulatory element at -3703/-3686 bp binds to the liver-enriched factor, CCAAT/enhancer-binding protein-alpha, whereas cell-specific regulatory elements at -3895/-3890 and -3761/-3744 bp bind proteins of unknown identity. While the cell-specific regulatory element at -3761/-3744 bp contains sequences that resemble binding sites for CCAAT/enhancer-binding protein, activator protein-1, cyclic AMP response element binding protein, and NF-1, none of these proteins appear to bind to this DNA fragment. These data suggest that cell-specific differences in T3 responsiveness of the malic enzyme gene are mediated in large part by nonreceptor proteins that augment the transcriptional activity of the nuclear T3 receptor in hepatocytes.

Animals↗