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Search Results: 1 - 10 of 11786 matches for " Laura Kasman "
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Barriers to coliphage infection of commensal intestinal flora of laboratory mice
Laura M Kasman
Virology Journal , 2005, DOI: 10.1186/1743-422x-2-34
Abstract: Contrary to expectations, coliphage were not evident in the GI tracts of laboratory mice, although they were occasionally detected in feces. Commensal flora showed extreme variability within groups of mice despite identical handling and diet. Less than 20% of 48 mice tested carried E. coli in their gut, and of 22 commensal E. coli strains isolated and tested, 59% were completely resistant to infection by lambda, M13, P1, T4, T7, and PhiX174 coliphage. Lysogeny could not be demonstrated in the commensal strains as mitomycin C failed to induce detectable phage. Pre-existing immunity to phages was not evident as sera and fecal washes did not contain significant antibody titers to six laboratory phage types.Lack of sufficient susceptible host bacteria seems to be the most likely barrier to establishment of new coliphage infections in the mouse gut.Coliphage have traditionally been isolated from sewage, where they arrived, presumably, after passing through the GI tracts of animals inhabited by commensal coliform bacteria. However, information on the interaction of natural coliphage with the commensal flora of the GI tract in situ is sparse. The results of ingestion of defined high titer bacteriophage preparations by laboratory animals or by humans have been described in many previous studies (reviewed in [1]). Although there is evidence in some reports of coliphage replication in the gut, the phage infections are consistently transient, becoming undetectable in 3–10 days [2-4]. Notable exceptions are cases of gnotobiotic mice inoculated with defined phage-host systems, in which phage and host populations in feces were detectable for up to 98 days [4]. However, in animals with complex, established gastrointestinal microflora, observations concur that exogenous phage do not establish sustained productive infections of the commensal bacteria. The nature of this apparent barrier to persistent bacteriophage infection of the normal GI tract is of practical interest since as pa
Histone Deacetylase Inhibitors Restore Cell Surface Expression of the Coxsackie Adenovirus Receptor and Enhance CMV Promoter Activity in Castration-Resistant Prostate Cancer Cells
Laura Kasman,Georgiana Onicescu,Christina Voelkel-Johnson
Prostate Cancer , 2012, DOI: 10.1155/2012/137163
Abstract: Adenoviral gene therapy using the death receptor ligand TRAIL as the therapeutic transgene can be safely administered via intraprostatic injection but has not been evaluated for efficacy in patients. Here we investigated the efficacy of adenoviral TRAIL gene therapy in a model of castration resistant prostate cancer and found that intratumoral injections can significantly delay tumor growth but cannot eliminate established lesions. We hypothesized that an underlying cause is inefficient adenoviral delivery. Using the LNCaP progression model of prostate cancer we show that surface CAR expression decreases with increasing tumorigenicity and that castration resistant C4-2b cells were more difficult to transduce with adenovirus than castration sensitive LNCaP cells. Many genes, including CAR, are epigenetically silenced during transformation but a new class of chemotherapeutic agents, known as histone deacetylase inhibitors (HDACi), can reverse this process. We demonstrate that HDACi restore CAR expression and infectivity in C4-2b cells and enhance caspase activation in response to infection with a TRAIL adenovirus. We also show that in cells with high surface CAR expression, HDACi further enhance transgene expression from the CMV promoter. Thus HDACi have multiple beneficial effects, which may enhance not only viral but also non-viral gene therapy of castration resistant prostate cancer. 1. Introduction Epigenetic alterations, such as aberrant activity of histone deacetylases, are frequently observed in malignancies. Acetylation of histones is associated with less condensed chromatin and a transcriptionally active gene status, while deacetylation is associated with transcriptional silencing. Histone deacetylase inhibitors (HDACiS) were originally found to reverse the malignant phenotype of transformed cells and have subsequently been developed as a new group of chemotherapeutic agents. HDACi can affect numerous signaling pathways to inhibit growth or angiogenesis and induce apoptosis or senescence [1, 2]. Using two HDACi under evaluation for the treatment of prostate cancer, we previously demonstrated that both romidepsin (also known as depsipeptide) and MS-275 enhanced the in vitro efficacy of adenoviral TRAIL gene therapy in castration-sensitive LNCaP prostate cancer cells [3]. This effect was selective for the malignant cells as primary cultures of prostate epithelial cells were not adversely affected [3]. TRAIL gene therapy has been evaluated for safety in prostate cancer patients with locally confined disease scheduled for prostatectomy [4]. Although
Adenoviral infectivity of exfoliated viable cells in urine: Implications for the detection of bladder cancer
Anuradha Murali, Laura Kasman, Christina Voelkel-Johnson
BMC Cancer , 2011, DOI: 10.1186/1471-2407-11-168
Abstract: Exfoliated cells from urine were obtained from 36 human subjects (> 40 years old). An adenovirus in which GFP expression is under control of the survivin promoter (Ad.Surv.GFP) was generated. An adenovirus in which GFP is expressed from the CMV promoter served as a control. GFP expression was analyzed by fluorescent microscopy and quantified by flow cytometry.Short-term cultures from exfoliated cells in urine could be established in 16 of 31 samples. These cultures were successfully transduced with Ad.CMV.GFP. Analysis of GFP expression following transduction with Ad.Surv.GFP, indicated that the survivin promoter was preferentially active in UM-UC-3 bladder cancer cells compared to non-malignant UROtsa cells. Interestingly, baseline levels of GFP expression in cultures from exfoliated cells in urine exhibited higher baseline levels than UROtsa following transduction with Ad.Surv.GFP.We demonstrated the feasibility of establishing and analysing short-term cultures isolated from exfoliated cells in voided urine by means of adenoviral transduction, thereby forming the foundation for future studies to determine the specificity and sensitivity of a non-invasive test based on survivin promoter activity.According to the American Cancer Society bladder cancer is the 5th highest in estimated new cases of cancers by site with 14,680 bladder cancer deaths and 70,530 new diagnoses in 2010 [1,2]. Bladder cancer can be categorized into non-muscle-invasive bladder cancer or muscle-invasive bladder cancer where 80% of the newly diagnosed cancers are non-muscle-invasive bladder cancer. Unfortunately, 70% of the patients will have recurrence of the disease and 10-30% will progress to muscle-invasive disease. Bladder cancer is detected as a result of incidental findings or by presenting hematuria. While hematuria is associated with benign conditions such as urinary tract infections and urolithiasis, 10% of the patients with gross hematuria are diagnosed with bladder cancer [3]. Contra
Efficiency, productivity and stock performance: Evidence from the Turkish banking sector
Kasman Saadet,Kasman Adnan
Panoeconomicus , 2011, DOI: 10.2298/pan1103355k
Abstract: This paper investigates the link between stock performance of the listed commercial banks in the Turkish stock exchange and three measures of bank performance, such as technical efficiency, scale efficiency and productivity for the period 1998-2008. The relationship between efficiency and stock returns is investigated by running a regression of stock returns on measures of performance and some bank specific variables. The results indicate that the changes in three measures of performance have positive and significant effect on stock returns, suggesting that stocks of technical efficient, scale efficient and productive banks tend to outperform their inefficient and unproductive rivals.
El proceso de consolidación del sistema de partidos en Argentina. Democratización y elecciones del 2007
Romina Kasman
Revista Enfoques : Ciencia Política y Administración Pública , 2007,
Abstract: This article analyzes the characteristics of the democratization process in contemporary Argentina, using the following variables: party system, working dynamics and the game rules in the political system and the presidential form of government, all of which determine the degree of institutionalization and instauration of the contemporary Argentinean democratic regime. For this the author uses two central axis of analysis: the State reform and the political reform. Finally, today’s politics with Néstor Kirchner are analyzed in relation with the development of substantial political system reforms which favors a greater democratization of the regime.
Bispectral KP Solutions and Linearization of Calogero-Moser Particle Systems
Alex Kasman
Physics , 1994, DOI: 10.1007/BF02099435
Abstract: A new construction using finite dimensional dual grassmannians is developed to study rational and soliton solutions of the KP hierarchy. In the rational case, properties of the tau function which are equivalent to bispectrality of the associated wave function are identified. In particular, it is shown that there exists a bound on the degree of all time variables in tau if and only if the wave function is rank one and bispectral. The action of the bispectral involution, beta, in the generic rational case is determined explicitly in terms of dual grassmannian parameters. Using the correspondence between rational solutions and particle systems, it is demonstrated that beta is a linearizing map of the Calogero-Moser particle system and is essentially the map sigma introduced by Airault, McKean and Moser in 1977.
Nested Bethe Ansatz and Finite Dimensional Canonical Commutation Relations
Alex Kasman
Physics , 2000,
Abstract: Recent interest in discrete, classical integrable systems has focused on their connection to quantum integrable systems via the Bethe equations. In this note, solutions to the rational nested Bethe ansatz (RNBA) equations are constructed using the ``completed Calogero-Moser phase space'' of matrices which satisfy a finite dimensional analogue of the canonical commutation relationship. A key feature is the fact that the RNBA equations are derived only from this commutation relationship and some elementary linear algebra. The solutions constructed in this way inherit continuous and discrete symmetries from the CM phase space.
Spectral Difference Equations Satisfied by KP Soliton Wavefunctions
Alex Kasman
Physics , 1998, DOI: 10.1088/0266-5611/14/6/008
Abstract: The Baker-Akhiezer (wave) functions corresponding to soliton solutions of the KP hierarchy are shown to satisfy eigenvalue equations for a commutative ring of translational operators in the spectral parameter. In the rational limit, these translational operators converge to the differential operators in the spectral parameter previously discussed as part of the theory of "bispectrality". Consequently, these translational operators can be seen as demonstrating a form of bispectrality for the non-rational solitons as well.
n-Schur Functions and Determinants on an Infinite Grassmannian
Alex Kasman
Physics , 1998,
Abstract: A set of functions is defined which is indexed by a positive integer $n$ and partitions of integers. The case $n=1$ reproduces the standard Schur polynomials. These functions are seen to arise naturally as a determinant of an action on the frame bundle of an infinite grassmannian. This fact is well known in the case of the Schur polynomials ($n=1$) and has been used to decompose the $\tau$-functions of the KP hierarchy as a sum. In the same way, the new functions introduced here ($n>1$) are used to expand quotients of $\tau$-functions as a sum with Plucker coordinates as coefficients.
Grassmannians, Nonlinear Wave Equations and Generalized Schur Functions
Alex Kasman
Physics , 1998,
Abstract: A set of functions is introduced which generalizes the famous Schur polynomials and their connection to Grasmannian manifolds. These functions are shown to provide a new method of constructing solutions to the KP hierarchy of nonlinear partial differential equations. Specifically, just as the Schur polynomials are used to expand tau-functions as a sum, it is shown that it is natural to expand a quotient of tau-functions in terms of these generalized Schur functions. The coefficients in this expansion are found to be constrained by the Pl\"ucker relations of a grassmannian.
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