Biomedical subjects

Cynthia Gross

Publications and source records attributed to Cynthia Gross.

5 recordsLinked to original sources

PubMed2006

Gene-based delivery of IFN-beta is efficacious in a murine model of experimental allergic encephalomyelitis.

Experimental allergic encephalomyelitis (EAE) is a model of central nervous system (CNS) inflammation that follows immunization with certain CNS antigens. The course and clinical manifestations of EAE are similar to those of multiple sclerosis (MS) in humans; therefore, EAE has become an accepted animal model to study MS. The purpose of this study was to demonstrate that systemic expression of murine interferon-beta (IFN-beta) (MuIFN-beta), following intramuscular (i.m.) delivery of plasmid DNA encoding MuIFN-beta to the hind limb of mice, is effective in reducing the clinical manifestations of disease in a model of EAE. The results of the study demonstrate that gene-based delivery of MuIFN-beta caused significantly decreased clinical scores compared with delivery of the null vector. A single injection of the MuIFN-beta plasmid was as effective in reducing the severity of the disease as an every other day injection of MuIFN-beta protein.

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PubMed2006

Mx1 and IP-10: biomarkers to measure IFN-beta activity in mice following gene-based delivery.

Recombinant interferon-beta (IFN-beta) protein is used successfully for the treatment of multiple sclerosis (MS). Gene therapy might be an alternative approach to overcome drawbacks occurring with IFN-beta protein therapy. A critical issue in developing a new approach is detection of biologically active IFN-beta in preclinical models. The goal of the present study was to determine if Mx1 and IP-10, which are known to be activated after IFN-beta treatment in humans, can be used as biomarkers in mice. In three in vivo experiments, the correlation between different methods of murine IFN-beta (MuIFN-beta) delivery and biomarker induction was studied: (1) bolus protein delivery by intravenous (i.v.) or intramuscular (i.m.) injection, (2) gene-based delivery of IFN- beta by i.m. injection of plasmid DNA, followed by electroporation, and (3) gene-based delivery of IFN-beta by i.m. injection of adenovirus-associated type 1 (AAV1). Short-term induction of Mx1 mRNA and IP-10 was observed after treatment with bolus MuIFN-beta protein. Long-term induction of both biomarkers was observed after IFN-beta plasmid DNA delivery or when AAV1 was used as the vector. The experiments demonstrate that gene-based delivery provides sustained levels of IFN-beta compared with bolus protein injection and that Mx1 RNA and IP-10 can be used to monitor biologically active circulating plasma MuIFN-beta protein in mice.

Animals↗

PubMed2006

Anti-EphA2 antibodies decrease EphA2 protein levels in murine CT26 colorectal and human MDA-231 breast tumors but do not inhibit tumor growth.

The EphA2 receptor tyrosine kinase has been shown to be over-expressed in cancer and a monoclonal antibody (mAb) that activates and down-modulates EphA2 was reported to inhibit the growth of human breast and lung tumor xenografts in nude mice. Reduction of EphA2 levels by treatment with anti-EphA2 siRNA also inhibited tumor growth, suggesting that the anti-tumor effects of these agents are mediated by decreasing the levels of EphA2. As these studies employed human tumor xenograft models in nude mice with reagents whose cross reactivity with murine EphA2 is unknown, we generated a mAb (Ab20) that preferentially binds, activates, and induces the degradation of murine EphA2. Treatment of established murine CT26 colorectal tumors with Ab20 reduced EphA2 protein levels to approximately 12% of control tumor levels, yet had no effect on tumor growth. CT26 tumor cell colonization of the lung was also not affected by Ab20 administration despite having barely detectable levels of EphA2. We also generated and tested a potent agonistic mAb against human EphA2 (1G9-H7). No inhibition of humanMDA-231 breast tumor xenograft growth was observed despite evidence for >85% reduction of EphA2 protein levels in the tumors. These results suggest that molecular characteristics of the tumors in addition to EphA2 over-expression may be important for predicting responsiveness to EphA2-directed therapies.

Animals↗

PubMed2006

The validity of A new practical quality of life measure in patients on renal replacement therapy.

OBJECTIVE: A new quality of life measure, apart of the National Health and Welfare 2003 survey, is a promising tool for outcome evaluation of clinical practice due to its brevity, validity, reliability, and providing easy interpretation against general population norm-based scores. The measure consisting of 9-items, and so called 9-item Thai Health status Assessment Instrument (9-THAI) was used to assess its validity and reliability in patients on renal replacement therapy (RRT). MATERIAL AND METHOD: Three hundred and two patients on RRT who visited Srinagarind Hospital from March to May 2005 were studied Convergent and divergent validity were assessed using SF-36 as the concurrent measure. Concurrent validity was also assessed using hematocrit level and hospitalization history in the last year as concurrent clinical measures. Test-retest reliability was studied by repeated measure within one 1 month. Responsiveness of 9-THAI was studied in patients who reported health improvement. RESULTS: Results of correlations between 9-THAI and SF-36 domains were as hypothesized 9-THAI scores were significantly correlated with hematocrit level and hospitalization history. The results confirmed the validity of 9-THAI for use as a quality of life measure. Intraclass correlation coefficients of 9-THAI scores in stable patients were satisfactory. Among patients on RRT who reported overall health improvement, 9-THAI scores significantly increased, thus adding further evidence of the responsiveness of 9-THAI. CONCLUSION: The 9-THAI is a valid and reliable generic health status measure that can be used as an ideal core in a battery of quality of life measures in clinical practice for patients on RRT.

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PubMed2002

Barley stripe mosaic virus-induced gene silencing in a monocot plant.

RNA silencing of endogenous plant genes can be achieved by virus-mediated, transient expression of homologous gene fragments. This powerful, reverse genetic approach, known as virus-induced gene silencing (VIGS), has been demonstrated only in dicot plant species, where it has become an important tool for functional genomics. Barley stripe mosaic virus (BSMV) is a tripartite, positive-sense RNA virus that infects many agriculturally important monocot species including barley, oats, wheat and maize. To demonstrate VIGS in a monocot host, we modified BSMV to express untranslatable foreign inserts downstream of the gammab gene, in either sense or antisense orientations. Phytoene desaturase (PDS) is required for synthesizing carotenoids, compounds that protect chlorophyll from photo-bleaching. A partial PDS cDNA amplified from barley was 90, 88 and 74% identical to PDS cDNAs from rice, maize and Nicotiana benthamiana, respectively. Barley infected with BSMV expressing barley, rice or maize PDS fragments became photo-bleached and accumulated phytoene (the substrate for PDS) in a manner similar to plants treated with the chemical inhibitor of PDS, norflurazon. In contrast, barley infected with wild-type BSMV, or BSMV expressing either N. benthamiana PDS or antisense green fluorescent protein (GFP), did not photo-bleach or accumulate phytoene. Thus BSMV silencing of the endogenous PDS was homology-dependent. Deletion of the coat protein enhanced the ability of BSMV to silence PDS. This is the first demonstration of VIGS in a monocot, and suggests that BSMV can be used for functional genomics and studies of RNA-silencing mechanisms in monocot plant species.

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