48 research outputs found

    Busulphan-Cyclophosphamide Cause Endothelial Injury, Remodeling of Resistance Arteries and Enhanced Expression of Endothelial Nitric Oxide Synthase

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    Stem cell transplantation (SCT) is a curative treatment for malignant and non malignant diseases. However, transplantation-related complications including cardiovascular disease deteriorate the clinical outcome and quality of life. We have investigated the acute effects of conditioning regimen on the pharmacology, physiology and structure of large elastic arteries and small resistance-sized arteries in a SCT mouse model. Mesenteric resistance arteries and aorta were dissected from Balb/c mice conditioned with busulphan (Bu) and cyclophosphamide (Cy). In vitro isometric force development and pharmacology, in combination with RT-PCR, Western blotting and electron microscopy were used to study vascular properties. Compared with controls, mesenteric resistance arteries from the Bu-Cy group had larger internal circumference, showed enhanced endothelium mediated relaxation and increased expression of endothelial nitric oxide synthase (eNOS). Bu-Cy treated animals had lower mean blood pressure and signs of endothelial injury. Aortas of treated animals had a higher reactivity to noradrenaline. We conclude that short-term consequences of Bu-Cy treatment divergently affect large and small arteries of the cardiovascular system. The increased noradrenaline reactivity of large elastic arteries was not associated with increased blood pressure at rest. Instead, Bu-Cy treatment lowered blood pressure via augmented microvascular endothelial dependent relaxation, increased expression of vascular eNOS and remodeling toward a larger lumen. The changes in the properties of resistance arteries can be associated with direct effects of the compounds on vascular wall or possibly indirectly induced via altered translational activity associated with the reduced hematocrit and shear stress. This study contributes to understanding the mechanisms that underlie the early effects of conditioning regimen on resistance arteries and may help in designing further investigations to understand the late effects on vascular system

    Mining Predicted Essential Genes of Brugia malayi for Nematode Drug Targets

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    We report results from the first genome-wide application of a rational drug target selection methodology to a metazoan pathogen genome, the completed draft sequence of Brugia malayi, a parasitic nematode responsible for human lymphatic filariasis. More than 1.5 billion people worldwide are at risk of contracting lymphatic filariasis and onchocerciasis, a related filarial disease. Drug treatments for filariasis have not changed significantly in over 20 years, and with the risk of resistance rising, there is an urgent need for the development of new anti-filarial drug therapies. The recent publication of the draft genomic sequence for B. malayi enables a genome-wide search for new drug targets. However, there is no functional genomics data in B. malayi to guide the selection of potential drug targets. To circumvent this problem, we have utilized the free-living model nematode Caenorhabditis elegans as a surrogate for B. malayi. Sequence comparisons between the two genomes allow us to map C. elegans orthologs to B. malayi genes. Using these orthology mappings and by incorporating the extensive genomic and functional genomic data, including genome-wide RNAi screens, that already exist for C. elegans, we identify potentially essential genes in B. malayi. Further incorporation of human host genome sequence data and a custom algorithm for prioritization enables us to collect and rank nearly 600 drug target candidates. Previously identified potential drug targets cluster near the top of our prioritized list, lending credibility to our methodology. Over-represented Gene Ontology terms, predicted InterPro domains, and RNAi phenotypes of C. elegans orthologs associated with the potential target pool are identified. By virtue of the selection procedure, the potential B. malayi drug targets highlight components of key processes in nematode biology such as central metabolism, molting and regulation of gene expression

    Flow-induced-microgel adsorption of high-molecular weight polyacrylamides

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    Water soluble polymers are widely used in oil and gas reservoirs and usually injected into the reservoir rocks to alter their flow properties. The rheologies of the polymer solution and their adsorption or interaction with the porous system are crucial for the success of the injection. This work aims to investigate the formation of residual polymer multilayers as a result of the flow of aqueous solutions of high-molecular-weight cationic (CPAM) and non-ionic (PAM) polyacrylamides through single, circular and rectangular capillaries.Polymer solutions in de-ionized water and weak brine were injected at different flow rates into glass capillaries of circular and rectangular cross sectional area. The adsorption energy and layer thickness on glass surfaces of these polymer solutions have been investigated by Al-Hashmi and Luckham (2010) under static conditions using colloidal force measurements. The apparent viscosity of the polymer in solution on both increasing and decreasing the shear rate are presented to indicate the thixotropic or anti-thixotropic behaviour of the solution. Also, the viscosity-time curves are presented to investigate the rheopectic behaviour of the polymer solutions.The flow CPAM in water solution through the capillaries resulted in very thick residual polymer layers, around 15 times thicker than those measured under static conditions. This solution shows both anti-thixtropic and rheopectic behaviour, which may be attributed to flow-induced-microgel formations in the bulk of the polymer solution. The same polymer solution has shown almost instantaneous adsorption from the colloidal force measurements due to electrostatic attraction of the cationic groups of the polymer to the negative glass surface. Such thick layers are not formed when CPAM in 0.34. M NaCl is used. Although it has shown strong adsorption on glass, the CPAM in 0.34. M NaCl exhibits neither anti-thixotropic nor rheopectic behaviour. Though it has shown rheopectic behaviour, the non-ionic polyacrylamide in water solution does not result in significantly thick layers, which might be due to its weak adsorption on glass.In the current study, a new mechanism is proposed to attribute the apparent formation of residual multilayer under the name of flow-induced-microgel adsorption (FIMGA). According to the new mechanism, two criteria have to be satisfied for polymer multilayer formation: the formation of sizable shear-induced-microgel structures in the bulk of the solution, and sufficiently high adsorption energy of the polymer to the solid surface. The new understanding in view of this new mechanism will contribute to more successful applications of polymers in oilfields. It will also allow faster screening of the chemicals for a specific application which may warrant different characteristics of flow and adsorption. For example, polymers used in enhanced oil recovery should have high injectivity and low adsorption. On the other hand, high adsorption and thick residual polymer layers are the key for a successful use of polymers in water shut-off in oil and gas wells
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