Browsing by Author "Elvinger, Francois"
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- Estrogen up-regulates inducible nitric oxide synthase, nitric oxide, and cyclooxygenase-2 in splenocytes activated with T cell stimulants: Role of interferon-gammaKarpuzoglu, Ebru; Fenaux, Jillian B.; Phillips, Rebecca A.; Lengi, Andrea J.; Elvinger, Francois; Ahmed, Sattar Ansar (Endocrine Society, 2006-02)Estrogen is implicated in many autoimmune diseases and is a robust immunomodulator. For example, it regulates interferon (IFN)-gamma, a cytokine believed to up-regulate inducible nitric oxide synthase (iNOS). A notable gap in the literature is a lack of information on the regulation of nitric oxide in immune tissues by estrogen. We now show that activation of splenocytes with T cell stimulants [concanavalin-A (Con-A) or anti-CD3 antibodies] results in copious release of nitric oxide in splenocyte cultures from estrogen-treated but not placebo-treated mice. Moreover, even a low dose of T cell stimulants induced nitric oxide in splenocytes from estrogen-treated, but not placebo-treated, mice. Con-A-activated splenocytes from estrogen-treated mice also have up-regulated iNOS mRNA, iNOS protein, and cyclooxygenase-2 (a nitric oxide-regulated downstream proinflammatory protein) when compared with controls. Our studies suggest that the induction of nitric oxide by activated splenocytes from estrogen-treated mice is mediated in part by IFN gamma. First, blocking costimulatory signals mediated through interactions of CD28 and B7 molecules by CTLA-4Ig markedly decreased not only IFN gamma but also nitric oxide. Second, estrogen treatment of IFN gamma-knockout (IFN gamma(-)/(-)) mice did not induce iNOS protein or nitric oxide. Finally, in vitro addition of recombinant IFN gamma to Con-A-activated splenocytes from IFN gamma((-)/(-)) mice induced iNOS protein primarily in estrogen-treated mice. Overall, this is the first report to show that estrogen treatment up-regulates IFN gamma-inducible-iNOS gene expression, iNOS protein, nitric oxide, and cyclooxygenase-2 as an indirect consequence of activation of T cells. These findings may have wide implications to immunity and inflammatory disorders including female-predominant autoimmune diseases.
- Prevalence of agglutinating antibodies to Sarcocystis neurona in raccoons (Procyon lotor) from an urban area of VirginiaHancock, K.; Zajac, Anne M.; Elvinger, Francois; Lindsay, David S. (American Society of Parasitology, 2004-08)Equine protozoal myeloencephalitis is the most important protozoan disease of horses in North America and is usually caused by Sarcocystis neurona. Natural and experimentally induced cases of encephalitis caused by S. neurona have been reported in raccoons (Procyon lotor) and raccoons are an intermediate host for this parasite. A 3-yr-long serological survey was conducted to determine the prevalence of agglutinating antibodies to S. neurona in raccoons collected from Fairfax County, Virginia, a suburban-urban area outside Washington, D.C. Samples from 469 raccoons were examined, and agglutinating antibodies ( greater than or equal to 1:50 dilution) were found in 433 (92.3%) of the raccoons. This study indicates that exposure to S. neurona is high in this metropolitan area.
- Prevalence of antibodies to Toxoplasma gondii in raccoons (Procyon lotor) from an urban area of northern VirginiaHancock, K.; Thiele, L. A.; Zajac, Anne M.; Elvinger, Francois; Lindsay, David S. (American Society of Parasitology, 2005-06)Raccoons (Procyon lotor) are intermediate hosts for Toxo-plasma gondii, and clinical toxoplasmosis in raccoons has been reported. A 2-yr serological survey was conducted to determine the prevalence of antibodies to T. gondii in raccoons collected from Fairfax County, Virginia, a suburban/urban area outside Washington, D.C. Serum samples from 256 raccoons were examined for T. gondii antibodies at a 1:50 dilution using the modified direct agglutination test. Results indicated that 216 (84.4%) of the raccoons had been exposed to T. gondii. Our results indicate that raccoons in this area of Virginia are frequently exposed to T gondii. Domestic cats were common in the study area and may have served as a source of oocysts for raccoons and the food items of raccoons.
- Prevalence of antibodies to Trypanosoma cruzi in raccoons (Procyon lotor) from an urban area of northern VirginiaHancock, K.; Zajac, Anne M.; Pung, O. J.; Elvinger, Francois; Rosypal, A. C.; Lindsay, David S. (American Society of Parasitology, 2005-04)Raccoons (Procvon lotor) are reservoir hosts for Trypanosoma cruzi. A 3-yr-long serological survey was conducted to determine the prevalence of antibodies to this zoonotic parasite in raccoons collected from Fairfax County. Virginia, a suburban/urban area outside Washington, D.C. Serum samples from 464 raccoons were examined for T. cruzi antibodies at a 1:40 dilution with an indirect fluorescent antibody test (IFAT) and Brazil strain T. cruzi amastigotes and trypomastigotes as antigen. A positive IFAT test was found in 154 (33%) of the 464 samples. The yearly prevalence was 49 of 132 (37%) in 2000; 19 of 120 (16%) in 2001; and 86 of 212 (41%) in 2002. Our study indicates that raccoons in this area of Virginia are frequently exposed to T cruzi.