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Biomedical subjects

S X Fan

Publications and source records attributed to S X Fan.

12 recordsLinked to original sources
PubMed2006

Olaquindox and cyadox stimulate growth and decrease intestinal mucosal immunity of piglets orally inoculated with Escherichia coli.

One hundred and fifty piglets were randomly allotted to one of six treatments to determine the effects of olaquindox and cyadox on growth and intestinal immune response including the number of intraepithelial lymphocytes and immunoglobulin A secreting cells (ASCs) during the three-week period. A 2 x 3 factorial arrangement of treatments was employed with the following factors: (1) Escherichia coli (O(139):K(88), 10(10) CFU) inoculation or control and (2) no antimicrobials, 100 mg/kg olaquindox and 100 mg/kg cyadox in the basal diet respectively. The antimicrobial supplementations improved (p < 0.01) average daily gain and feed conversion ratio (FCR) during the experiment. Average daily gain and FCR in the cyadox-supplemented pigs were higher (p < 0.05) than those in the olaquindox-supplemented pigs. Intraepithelial lymphocytes and ASCs decreased (p < 0.05) when the diets were supplemented. Jejunal ASCs in the cyadox-supplemented pigs were lower (p < 0.05) than those in the olaquindox-supplemented pigs. Olaquindox and cyadox suppressed E. coli-induced intestinal immune activation, which may be involved in the observed growth promotion.

Animal Feed↗
PubMed1998

Overexpression of protein kinase C alpha enhances lipopolysaccharide-induced nitric oxide formation in vascular smooth muscle cells.

Our previous studies showed that lipopolysaccharide (LPS)-induced nitric oxide (NO) synthesis in cardiovascular tissues is attenuated by protein kinase C (PKC) inhibitors. In the current study, we identify a specific PKC isotype involved in the LPS signal transduction pathway that leads to NO formation in rat vascular smooth muscle cells (VSMC). VSMC were transfected with a mammalian expression vector containing a full length PKCalpha cDNA insert, and a stable transfectant overexpressing PKCalpha was obtained as evidenced by increased expression of PKCalpha mRNA and protein. In response to 100 ng/ml LPS stimulation, the PKCalpha transfectants showed a 1.8-fold increase in PKC activity at 30 min and a twofold increase in NO production over 24 hr compared with cells transfected with control plasmids. The LPS-stimulated increase in NO synthesis in PKCalpha transfectants was blocked by the specific PKCalpha inhibitor Gö 6976. After 6 hr LPS treatment, PKCalpha-transfected and control cells showed equivalent increases in mRNA and protein for the inducible NO synthase. NO synthase activity of the cell extracts assayed in the presence of excess substrate and cofactors was not significantly different between PKCalpha-transfected and control cells after LPS stimulation. However, mRNA levels for GTP cyclohydrolase I, a key enzyme in (6R)-tetrahydro-L-biopterin synthesis, and cationic amino acid transporter-2, involved in L-arginine transport, was enhanced in cells overexpressing PKCalpha compared with control cells. These results suggest that PKCalpha plays an important role in LPS-induced NO formation and that a significant portion of this effect may be by means of enhanced substrate availability to the inducible nitric oxide synthase enzyme.

Amino Acid Transport Systems, Basic↗
PubMed1997

Lipopolysaccharide-responsive protein kinase C isotypes in the adult rat aorta.

Previous studies have shown that protein kinase C (PKC) activity increases in cardiovascular tissue exposed to lipopolysaccharide (LPS). The objective of these experiments was to identify the PKC isotypes that respond to LPS treatment in the adult rat aorta. We found that PKC alpha, -delta, -epsilon, and -zeta isotypes are present in endothelium-intact aortas. The PKC alpha and -epsilon isotypes show two- to threefold increases in abundance after 3 h treatment with 100 ng/mL LPS, while PKC delta and -zeta levels do not increase. In contrast, mRNA for all of the PKC isotypes increased 3.5 to 12-fold during LPS treatment. Both PKC isotype and mRNA levels gradually diminished during 20 h of continuous LPS exposure. Concurrent treatment of the vessels with LPS plus 50 microM cycloheximide caused PKC alpha, -epsilon, and -zeta, but not -delta, isotypes to rapidly decrease in abundance while blunting the increase in PKC isotype mRNA. The major source for all of the PKC isotypes in the vessel is the vascular smooth muscle cells. These results indicate that LPS treatment induces time-dependent increases in PKC isotype mRNA expression and isotype-specific PKC activation and synthesis in vascular tissue.

Age Factors↗
PubMed1997

Vascular smooth muscle cells on Matrigel as a model for LPS-induced hypocontractility and NO formation.

Treatment of vascular tissue with low levels of lipopolysaccharide (LPS) induces nitric oxide synthase (NOS) activity and diminishes vascular contractility. However, in cultured vascular smooth muscle cells (VSMC), very high doses of LPS or the combination of LPS with cytokines are required for the induction of nitric oxide (NO) formation. The aims of this study were to establish a cell model to investigate LPS-induced hypocontractility and NO production and to test the hypothesis that responses of VSMC to LPS are differentiation regulated. We used Matrigel basement membrane matrix to maintain VSMC differentiation and found that VSMC cultured on Matrigel retained significant contractility in response to KCl stimulation. Incubation of VSMC with low levels of LPS(1-100 ng/ml) induced NOS mRNA and protein, induced NO production, and decreased cell contractility in a time- and dose-dependent fashion. The NOS inhibitor NG-nitro-L-arginine methyl ester (L-NAME) partially restored LPS-treated VSMC contractility, whereas L-arginine reversed the contractility-restoring effect of L-NAME. These results suggest that VSMC grown on Matrigel are a useful experimental model for investigations into signal transduction mechanisms responsible for LPS-induced vascular hypocontractility.

Animals↗
PubMed1996

Role of nitric oxide in sepsis-induced hyporeactivity in isolated rat lungs.

The aim of the present study was to test the hypothesis that pulmonary microvascular reactivity is depressed in sepsis and that inducible nitric oxide synthase (iNOS) contributes to the vascular hyporeactivity. Rats were made septic by cecal ligation and puncture. After 16 h, pulmonary vascular reactivity was evaluated by measurement of perfusion pressures while the vasculature was challenged with angiotensin II and KCl. The results showed that vascular reactivity was significantly depressed in lungs from septic rats in comparison to sham-operated controls. Pretreatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 100 microM) restored the depressed vasoreactivity while the nitric oxide (NO) synthase substrate L-arginine (1 mM) reversed the contraction-restoring effect of L-NAME. NO production in lungs from septic rats increased about 4-fold in comparison to sham-operated controls. iNOS protein was expressed in lung tissues, mainly the resistance vessels, from septic rats but not from sham-operated controls. Reverse transcription and polymerase chain reaction also showed a strong induction of iNOS mRNA in lung tissues from septic rats. These results suggest that increased iNOS expression and NO production may contribute to depressed pulmonary vascular reactivity in sepsis.

Animals↗
PubMed1994

Interferon-gamma protects primary monocytes against infection with human immunodeficiency virus type 1.

Monocytes treated with 500 IU/ml human recombinant interferon-gamma (rIFN-gamma) 1 day before and continuously after human immunodeficiency virus (HIV) infection showed no evidence of virus replication 7 days after addition of the viral inoculum. There was no HIV-associated cytopathic effect, no reverse transcriptase (RT) activity or p24 detected in culture fluids, and no HIV RNA or DNA in cell lysates. Furthermore, no evidence of HIV infection was evident in replicate cultures in which all IFN-gamma was removed at 7 days and the cells were cultured for an additional 3 weeks without IFN-gamma. The 50% inhibitory dose for reduction of maximum RT activity in HIV-infected monocyte cultures was about 1 IU/ml IFN-gamma. No increase in HIV replication was evident in monocytes treated with IFN-gamma at any concentration (0 to 5000 IU/ml) or at any time (7 days before to 10 days after HIV infection). In side-by-side experiments with identical monocytes and HIV-1 stock, rIFN-gamma was 10 to 20 times more effective than rIFN-alpha 2b for induction of antiviral activity. With both interferons, significant antiviral activity was evident with monocytes treated 1 day before, at the time of, or up to 3 days after infection. At 7 to 10 days after infection (a time at which less than 20% of total cells were infected with HIV) addition of even high concentrations of IFN-alpha or IFN-gamma had no effect on virus replication. These data suggest that the principal action of IFN-alpha and IFN-gamma was directed against the fluid-phase virus. Cell-cell spread of infection within the HIV-infected monocyte culture and extent of virus replication in HIV-infected cells were not affected by interferon treatment.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Increased efficacy of human natural interferon alpha (IFN-alpha n3) versus human recombinant IFN-alpha 2 for inhibition of HIV-1 replication in primary human monocytes.

Natural IFN-alpha n3, a purified mixture of many different natural IFN alpha species, was 10- to 100-fold more effective than equal concentrations of human rIFN-alpha 2b or rIFN-alpha 2a for inhibition of HIV replication in primary human monocytes. This difference was highly reproducible in multiple side-by-side experiments using the identical HIV-1 inoculum and the same monocyte target cells: natural IFN-alpha n3 was more effective than rIFN-alpha 2b at lower concentrations for protection against a constant HIV-1 inoculum; cells treated with natural IFN-alpha n3 were protected against a greater HIV-1 challenge than were cells treated with the same concentration of rIFN-alpha 2b. Fractionation of natural IFN-alpha n3 by reversed-phase high-pressure liquid chromatography (RP-HPLC) showed that most antiviral activity for HIV localized to discrete and reproducible peaks. The RP-HPLC peak that contained purified natural IFN-alpha 2b was the least effective fraction. These data suggest heterogeneity among IFN-alpha species for antiviral activity against HIV and may provide a molecular basis for more effective IFN-alpha therapy.

Cells, Cultured↗
PubMed1992

Potent anti-tumorigenic effect of tubeimoside 1 isolated from the bulb of Bolbostemma paniculatum (Maxim) Franquet.

Tubeimoside 1, one of the new triterpenoid saponins from the bulb of Bolbostemma paniculatum (Maxim) Franquet, had an anti-inflammatory effect on mouse ear edema induced by arachidonic acid and 12-O-tetradecanoylphorbol-13-acetate (TPA). Furthermore, a potent anti-tumorigenic effect of tubeimoside 1 was observed in 2-stage carcinogenesis of mouse skin after oral administration as well as topical application. Thus, tubeimoside 1 appears to be a promising agent for cancer chemoprevention.

Administration, Topical↗
PubMed1990

Cytogenetic findings in nine leiomyomas of the uterus.

Chromosomal analysis of nine benign leiomyomas of the uterus after short-term culture showed karyotypic abnormalities in four cases. All four exhibited multiple chromosome changes, including three cases characterized by complex chromosome rearrangements involving a number of chromosomes. Among others, these rearrangements included a translocation between chromosomes 12 and 14 in one case, a deletion of chromosome 7q in two cases, and both del(7q) and a complex translocation involving chromosomes 12 and 14 in another case. These results confirm the involvement of chromosomes 7, 12, and 14 in leiomyomas and indicate that benign tumors can also be characterized by complex cytogenetic changes.

Adult↗
PubMed1989

inv(12)(p11.2q13) in an endometrial polyp.

A benign endometrial polyp from a 50-year-old postmenopausal woman has been cytogenetically investigated. A single clonal karyotypic anomaly, inv(12)(p11.2q13), was found in about 30% of cells analyzed after short-term culture. This finding contributes further to the hypothesis that the chromosomal segment 12q13-q14, which is also involved in chromosomal rearrangements in uterine leiomyomas, pleomorphic adenomas of the salivary glands, lipomas, and myxoid liposarcomas, contains a gene or genes that are related to cellular proliferation rather than to malignant transformation.

Chromosome Banding↗