Synthesis, characterisation, DNA binding interactions, and biological activity of nickel Schiff base complexes

A series of fourteen new nickel Schiff base complexes was synthesised by a two-step procedure. Initially 2,4,6-trihydroxybenzaldehyde was reacted with 1-(2-chloroethyl)piperidine hydrochloride, 4-(2-chloroethyl)morpholine hydrochloride or 1-(3-chloropropyl)piperidine hydrochloride in the presence of K2CO3 to afford three organic precursor compounds featuring different pendant groups. These compounds were then successfully reacted with different diamines in the presence of Ni(II) to form a series of nickel Schiff base complexes featuring four pendant groups. All new organic compounds and nickel complexes were characterised using 1D and 2D nuclear magnetic resonance (NMR) spectroscopic methods, elemental microanalysis and electrospray ionisation mass spectrometry (ESI-MS). The solid-state structures of four nickel complexes were determined by single crystal X-ray crystallography and revealed that the coordination geometry around the nickel ion was square planar in each case. The ability of the nickel complexes to bind to the double stranded DNA molecule D2, the tetramolecular G-quadruplex Q4, the unimolecular G-quadruplex Q1 in its parallel, anti-parallel and hybrid topologies, the parallel unimolecular G-quadruplex c-KIT1, and the fluorescently labelled unimolecular G-quadruplex F21T, was investigated using ESI-MS and circular dichroism (CD) spectroscopy, Fluorescence Indicator Displacement (FID) assays, Fluorescence Resonance Energy Transfer (FRET) melting assays and molecular docking

DNA-binding interactions of nickel Schiff base complexes

A series of eleven different nickel Schiff base complexes was synthesized by a two-step procedure. Initially ethylenediamine, phenylenediamine or meso- 1,2-diphenylethylenediamine was reacted with either 2,3- or 2,5- dihydroxybenzaldehyde in the presence of Ni(II) to afford six novel dihydroxylated nickel Schiff base complexes. Five of these complexes were then successfully reacted with 1-(2-chloroethyl) piperidine hydrochloride to form a series of derivatives featuring two appended ethyl piperidine moieties. All new complexes were characterised using 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, elemental microanalysis and in some instances electrospray ionisation mass spectrometry (ESI-MS). The solidstate structures of three nickel complexes (5), (8) and (10) were determined by single crystal X-ray crystallography, and revealed that the coordination geometry around the nickel ion was square planar in each case. The ability of the nickel complexes containing appended ethyl piperidine groups to bind to a double-stranded 16mer DNA molecule, and a tetramolecular DNA quadruplex, was investigated using ESI-MS and circular dichroism (CD) spectroscopy. The results of these studies, as well as those performed simultaneously using a series of previously reported analogues prepared by the same synthetic pathway, but with 2,4- dihydroxybenzaldehyde as one of the initial reactants, enabled the effect of varying the position of the ethyl piperidine groups on DNA-binding properties to be explored. Generally, it was found that changing the position of the ethyl piperidine groups had only a small effect on binding affinity towards either type of DNA molecule. In most cases there was good agreement between orders of relative binding affinity towards a given DNA molecule determined using the two spectroscopic techniques. On some occasions, however, the results of binding studies conducted using ESI-MS and CD spectroscopy diverged significantly. This may have been the result of the two methods showing different sensitivities towards different aspects of the metal complex/DNA interaction, and the varying stabilities of the non-covalent complexes formed in these systems, to the gas phase environment of the ESI mass spectrometer or to the solution phase used in CD experiments

Cytosolic phosphoenolpyruate carboxykinase (PEPCKC) gene polymorphism in three chicken breeds

Phosphoenolpyruate carboxykinase (PEPCK) gene is an enzyme which has a key role in gluconeogenesis. In the chicken genome, there are two different types of PEPCK gene: mitochondrial PEPCK (PEPCK-M) and cytosolic PEPCK (PEPCK-C). In this study, 150 random samples from two native populations in Sistan and Baluchistan Province, namely, Khazak and Dashtiari, and Ross chicken were analyzed. DNA was extracted from feather pulps and PCR was carried out using appropriate primers (F2R2), which amplifies a 1000 bp fragment from the chicken PEPCK-C gene. The fragment covers from promoter to exon 2 of the gene. PCR products were then digested by restriction enzymes BstEII and ACil. Allelic as well as genotypic frequencies were determined and analyzed by Popgene software. The allelic frequencies BstEII for Khazak sample were A = 0.975 and B = 0.025; for Dashtiari sample; A = 0.95 and B = 0.05 and for Ross samples, A = 0.94 and B = 0.06. The allelic frequencies digestion by ACil for Khazak sample were A = 0.86 and B = 0.14; for Dashtiari sample, A = 0.98 and B = 0.02 and for Ross samples, A = 0.95 and B = 0.05. Haplotype analysis of two single nucleotide polymorphism (SNP) showed that there were four alleles and genotypes. The present results indicated that little polymorphism exists in the samples for this locus.Key words: Polymorphism, PEPCK gene, Sistan and Baluchistan native chicken, Khazak, Dashtiari

Experimental and Finite Element Analysis of Preloaded Bolted Joints Under Impact Loading

One of the primary parameters in analyzing bolted joints is preload in the bolt. We have considered several possible preload modeling techniques to analyze the effect of preload on the dynamic response of the bolted joints. Five different methods of applying preload in the nonlinear finite element analysis are evaluated. These methods are “force on bolt and nut”, “force on bolt shank”, “interference fit”, “thermal gradient” and “initial stress method”. Explicit and implicit analyses are used for transient response and preload generation in bolt respectively. Time history and shock response spectrum are used to compare experimental and simulation results. Simulation results compared fairly well with the experimental results

Genetic factors of hypertension in individuals with different rates of Na-Li counter -transport

Currently, hypertension is recognized as one of the most common cardio-vascular diseases. Recent studies indicate the multifactorial nature of this disease, in which much emphasis is given to genetic factors for their role in the development of this disease. With, results based on the identification of genetic markers associated with the risk of developing hypertension vary vastly and remain highly controversial, primarily due to the ethno-genetic and geographical features of the populations under study, there is an urgent need to identify a phenotypic trait that would allow analysis of associations with the risk of developing hypertension irrespective of an individual's ethnic background or geographical location. One such a prospective trait is the rate of Na-Li counter-transport, which remains unchanged for most of an individual's lifetime, with rare exceptions. Hence this study is aimed at identifying the contribution of gene polymorphisms of the renin-angiotensin system in the formation of genetic predisposition to hypertension in individuals with different rates of erythrocyte Na-Li counter-transport

Genetic factors of hypertension in individuals with different rates of Na-Li counter -transport

Currently, hypertension is recognized as one of the most common cardio-vascular diseases. Recent studies indicate the multifactorial nature of this disease, in which much emphasis is given to genetic factors for their role in the development of this disease. With, results based on the identification of genetic markers associated with the risk of developing hypertension vary vastly and remain highly controversial, primarily due to the ethno-genetic and geographical features of the populations under study, there is an urgent need to identify a phenotypic trait that would allow analysis of associations with the risk of developing hypertension irrespective of an individual's ethnic background or geographical location. One such a prospective trait is the rate of Na-Li counter-transport, which remains unchanged for most of an individual's lifetime, with rare exceptions. Hence this study is aimed at identifying the contribution of gene polymorphisms of the renin-angiotensin system in the formation of genetic predisposition to hypertension in individuals with different rates of erythrocyte Na-Li counter-transport

Risks and Benefits of Using a Commercially Available Ventricular Assist Device for Failing Fontan Cavopulmonary Support: A Modeling Investigation

Fontan patients often develop circulatory failure and are in desperate need of a therapeutic solution. A blood pump surgically placed in the cavopulmonary pathway can substitute the function of the absent sub-pulmonary ventricle by generating a mild pressure boost. However, there is currently no commercially available device designed for the cavopulmonary application; and the risks and benefits of implanting a ventricular assist device (VAD) originally designed for the left ventricular application on the right circulation of failing Fontan patients is not yet clear. Moreover, further research is needed to compare the hemodynamics between the two clinically-considered surgical configurations (Full Support and IVC Support) for cavopulmonary assist, with Full and IVC Support corresponding to the entire venous return or only the inferior venous return, respectively, being routed through the VAD. In this study, we used a numerical model of the failing Fontan physiology to evaluate the Fontan hemodynamic response to a left VAD during the IVC and Full supports. We observed that during the Full support the VAD improved the cardiac output while maintaining blood pressures within safe ranges, and lowered the IVC pressure to <15mmHg; however, we found a potential risk of lung damage at higher pump speeds due to the excessive pulmonary pressure elevation. IVC support the other hand, did not benefit the hemodynamics of the example failing Fontan patients, resulting in the superior vena cava pressure increasing to an unsafe level of >20 mmHg. The findings in this study may be helpful to surgeons for recognizing the risks of a cavopulmonary VAD and developing coherent clinical strategies for the implementation of cavopulmonary support

Tumor-reactive immune cells protect against metastatic tumor and induce immunoediting of indolent but not quiescent tumor cells

Two major barriers to cancer immunotherapy include tumor-induced immune suppression mediated by myeloid-derived suppressor cells and poor immunogenicity of the tumor-expressing self-antigens. To overcome these barriers, we reprogrammed tumor-immune cell cross-talk by combined use of decitabine and adoptive immunotherapy, containing tumor-sensitized T cells and CD25+ NKT cells. Decitabine functioned to induce the expression of highly immunogenic cancer testis antigens in the tumor, while also reducing the frequency of myeloid-derived suppressor cells and the presence of CD25+ NKT cells rendered T cells, resistant to remaining myeloid-derived suppressor cells. This combinatorial therapy significantly prolonged survival of animals bearing metastatic tumor cells. Adoptive immunotherapy also induced tumor immunoediting, resulting in tumor escape and associated disease-related mortality. To identify a tumor target that is incapable of escape from the immune response, we used dormant tumor cells. We used Adriamycin chemotherapy or radiation therapy, which simultaneously induce tumor cell death and tumor dormancy. Resultant dormant cells became refractory to additional doses of Adriamycin or radiation therapy, but they remained sensitive to tumor-reactive immune cells. Importantly, we discovered that dormant tumor cells contained indolent cells that expressed low levels of Ki67 and quiescent cells that were Ki67 negative. Whereas the former were prone to tumor immunoediting and escape, the latter did not demonstrate immunoediting. Our results suggest that immunotherapy could be highly effective against quiescent dormant tumor cells. The challenge is to develop combinatorial therapies that could establish a quiescent type of tumor dormancy, which would be the best target for immunotherapy