Search

The models developed in this work are used to study various thermodynamic properties of nanomaterials. A better agreement between theory and experiment indicates the validity of the proposed model. Since the model is simple and easy to use, we extend the theory to understand, how the thermodynamic properties of different nanomaterials depend on size and shape. The results were compared with previous theoretical work and experimental data. We have concluded that the model predicts a better agreement with previous theoretical work and experimental studies. Current research produces thermodynamic models for the Debye frequency, melting entropy, melting enthalpy, and Einstein temperature. To the best of our knowledge, such models are not yet available in the literature that works well.

Active DNA-dependent ATPase A Domain inhibitor (ADAADi) is the only known inhibitor of ATP-dependent chromatin remodeling proteins that targets the ATPase domain of these proteins. The molecule is synthesized by aminoglycoside phosphotransferase enzyme in the presence of aminoglycosides. ADAADi interacts with ATP-dependent chromatin remodeling proteins through motif Ia present in the conserved helicase domain, and thus, can potentially inhibit all members of this family of proteins. We show that mammalian cells are sensitive to ADAADi but with variable responses in different cell lines. ADAADi can be generated from a wide variety of aminoglycosides; however, cells showed differential response to ADAADi generated from various aminoglycosides. Using HeLa and DU145 cells as model system we have explored the effect of ADAADi on cellular functions. We show that the transcriptional network of a cell type is altered when treated with sub-lethal concentration of ADAADi. Although ADAADi has no known effects on DNA chemical and structural integrity, expression of DNA-damage response genes was altered. The transcripts encoding for the pro-apoptotic proteins were found to be upregulated while the anti-apoptotic genes were found to be downregulated. This was accompanied by increased apoptosis leading us to hypothesize that the ADAADi treatment promotes apoptotic-type of cell death by upregulating the transcription of pro-apoptotic genes. ADAADi also inhibited migration of cells as well as their colony forming ability leading us to conclude that the compound has effective anti-tumor properties.

This report represents the first study of keratinophilic fungi present in soils of Jamaica. Out of the 40 soil samples examined from different habitats, 30 (75%) were positive for the presence of keratinophilic fungi, yielding 36 isolates of keratinophilic fungi. Microsporum gypseum complex (represented by 16 isolates of M. gypseum, and four of M. fulvum) was most frequent, being present in 50% of the samples. A very high occurrence of this dermatophyte in Jamaican soil is of public health significance. The remaining isolates of keratinophilic fungi were represented by Chrysosporium spp (mainly C. indicum and C. tropicum) and Sepedonium sp.

Previously, we showed that aminoglycoside phosphotransferases catalyze the formation of a specific inhibitor of the SWI2/SNF2 proteins. Aminoglycoside phosphotransferases, for example neomycin-resistant genes, are used extensively as selection markers in mammalian transfections as well as in transgenic studies. However, introduction of the neomycin-resistant gene is fraught with variability in gene expression. We hypothesized that the introduction of neomycin-resistant genes into mammalian cells results in inactivation of SWI2/SNF2 proteins thereby leading to global epigenetic changes.Using fluorescence spectroscopy we have shown that the inhibitor, known as Active DNA-dependent ATPase ADomain inhibitor (ADAADi), binds to the SWI2/SNF2 proteins in the absence as well as presence of ATP and DNA. This binding occurs via a specific region known as Motif Ia leading to a conformational change in the SWI2/SNF2 proteins that precludes ATP hydrolysis. ADAADi is produced from a plethora of aminoglycosides including G418 and Streptomycin, two commonly used antibiotics in mammalian cell cultures. Mammalian cells are sensitive to ADAADi; however, cells stably transfected with neomycin-resistant genes are refractory to ADAADi. In resistant cells, endogenous SWI2/SNF2 proteins are inactivated which results in altered histone modifications. Microarray data shows that the changes in the epigenome are reflected in altered gene expression. The microarray data was validated using real-time PCR. Finally, we show that the epigenetic changes are quantized.The use of neomycin-resistant genes revolutionized mammalian transfections even though questions linger about efficacy. In this study, we have demonstrated that selection of neomycin-resistant cells results in survival of only those cells that have undergone epigenetic changes, and therefore, data obtained using these resistant genes as selection markers need to be cautiously evaluated.