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Search Results: 1 - 10 of 461472 matches for " Arti A. Ramkisoensing "
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Human Embryonic and Fetal Mesenchymal Stem Cells Differentiate toward Three Different Cardiac Lineages in Contrast to Their Adult Counterparts
Arti A. Ramkisoensing, Dani?l A. Pijnappels, Sa?d F. A. Askar, Robert Passier, Jim Swildens, Marie José Goumans, Cindy I. Schutte, Antoine A. F. de Vries, Sicco Scherjon, Christine L. Mummery, Martin J. Schalij, Douwe E. Atsma
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024164
Abstract: Mesenchymal stem cells (MSCs) show unexplained differences in differentiation potential. In this study, differentiation of human (h) MSCs derived from embryonic, fetal and adult sources toward cardiomyocytes, endothelial and smooth muscle cells was investigated. Labeled hMSCs derived from embryonic stem cells (hESC-MSCs), fetal umbilical cord, bone marrow, amniotic membrane and adult bone marrow and adipose tissue were co-cultured with neonatal rat cardiomyocytes (nrCMCs) or cardiac fibroblasts (nrCFBs) for 10 days, and also cultured under angiogenic conditions. Cardiomyogenesis was assessed by human-specific immunocytological analysis, whole-cell current-clamp recordings, human-specific qRT-PCR and optical mapping. After co-culture with nrCMCs, significantly more hESC-MSCs than fetal hMSCs stained positive for α-actinin, whereas adult hMSCs stained negative. Furthermore, functional cardiomyogenic differentiation, based on action potential recordings, was shown to occur, but not in adult hMSCs. Of all sources, hESC-MSCs expressed most cardiac-specific genes. hESC-MSCs and fetal hMSCs contained significantly higher basal levels of connexin43 than adult hMSCs and co-culture with nrCMCs increased expression. After co-culture with nrCFBs, hESC-MSCs and fetal hMSCs did not express α-actinin and connexin43 expression was decreased. Conduction velocity (CV) in co-cultures of nrCMCs and hESC-MSCs was significantly higher than in co-cultures with fetal or adult hMSCs. In angiogenesis bioassays, only hESC-MSCs and fetal hMSCs were able to form capillary-like structures, which stained for smooth muscle and endothelial cell markers.Human embryonic and fetal MSCs differentiate toward three different cardiac lineages, in contrast to adult MSCs. Cardiomyogenesis is determined by stimuli from the cellular microenvironment, where connexin43 may play an important role.
Challenges in Cancer Care of Elderly  [PDF]
Virender Suhag, B. S. Sunita, Arti Sarin, A. K. Singh
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2015, DOI: 10.4236/ijmpcero.2015.41004
Abstract:
As a result of vast global improvement of health care and living conditions, the world population is aging. In developed countries, more than half of the cancers occur in patients aged 70 and older. In booming Asian nations, such as India, the aging trend is particularly striking, and therefore geriatric oncology is rapidly coming at the foreground of oncology practice. As these patients have special needs and a different approach to treatment, there is a strong need for the emergence of geriatric oncology as a sub specialty in oncology. Scientific data show that a geriatric assessment identifies many problems in older people with cancer, adds prognostic information, and might improve the outcomes of these patients. There is a genuine unmet requirement to design and implement the following: development of individually tailored geriatric assessment tools for different oncology centers; cooperation of aging and cancer research in the understanding of cancer biology, aging and physiology; improved clinical study designs; development of geriatric oncology programs; and screening tools for geriatric patients made accessible to family physicians.
Cancer, Malnutrition and Cachexia: We Must Break the Triad  [PDF]
Virender Suhag, B. S. Sunita, Arti Sarin, A. K. Singh
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2015, DOI: 10.4236/ijmpcero.2015.41009
Abstract:
Many factors can modify nutritional status in cancer patients, including cachexia, nausea and vomiting, decreased caloric intake or oncologic treatments causing malabsorption. The cachexia-anorexia syndrome is a complex metabolic syndrome associated with cancer and some other palliative conditions characterized by involuntary weight loss involving fat and muscle, anorexia, early satiety, fatigue and weakness due to shifts in metabolism caused by tumour by-products and cytokines. Cachexia is a distressing and debilitating condition, affecting significant numbers of patients with advanced disease and is the primary cause of death in about 20% of all patients with cancer. Though cachexia is most commonly associated with particular tumours, such as head and neck, gastrointestinal tract, pancreas, central nervous system and lung, it may affect any patient with any tumour at any site; no patient and no tumour are excluded. Current treatment for principally depends on its prevention rather than reversing the present disease state, and the clinical results are far from being satisfactory. A careful decision based on good clinical judgement is necessary before deciding to start either enteral or parenteral nutrition, to avoid a useless, costly and difficult treatment. Treatment should be directed toward improvement in the quality of life of the patient and should often include nutritional counseling. It should take into consideration both disease and treatment related factors as well as the cachexia syndrome itself.
Semiflexible polymers in a random environment
Arti Dua,Thomas A. Vilgis
Physics , 2004, DOI: 10.1063/1.1783272
Abstract: We present using simple scaling arguments and one step replica symmetry breaking a theory for the localization of semiflexible polymers in a quenched random environment. In contrast to completely flexible polymers, localization of semiflexible polymers depends not only on the details of the disorder but also on the ease with which polymers can bend. The interplay of these two effects can lead to the delocalization of a localized polymer with an increase in either the disorder density or the stiffness. Our theory provides a general criterion for the delocalization of polymers with varying degrees of flexibility and allows us to propose a phase diagram for the highly folded (localized) states of semiflexible polymers as a function of the disorder strength and chain rigidity.
Constrained dynamics of a polymer ring enclosing a constant area
Arti Dua,Thomas A. Vilgis
Physics , 2004, DOI: 10.1103/PhysRevE.71.021801
Abstract: The dynamics of a polymer ring enclosing a constant {\sl algebraic} area is studied. The constraint of a constant area is found to couple the dynamics of the two Cartesian components of the position vector of the polymer ring through the Lagrange multiplier function which is time dependent. The time dependence of the Lagrange multiplier is evaluated in a closed form both at short and long times. At long times, the time dependence is weak, and is mainly governed by the inverse of the first mode of the area. The presence of the constraint changes the nature of the relaxation of the internal modes. The time correlation of the position vectors of the ring is found to be dominated by the first Rouse mode which does not relax even at very long times. The mean square displacement of the radius vector is found to be diffusive, which is associated with the rotational diffusion of the ring.
Self-consistent variational theory for globules
Arti Dua,Thomas A. Vilgis
Physics , 2005, DOI: 10.1209/epl/i2005-10062-x
Abstract: A self-consistent variational theory for globules based on the uniform expansion method is presented. This method, first introduced by Edwards and Singh to estimate the size of a self-avoiding chain, is restricted to a good solvent regime, where two-body repulsion leads to chain swelling. We extend the variational method to a poor solvent regime where the balance between the two-body attractive and the three-body repulsive interactions leads to contraction of the chain to form a globule. By employing the Ginzburg criterion, we recover the correct scaling for the $\theta$-temperature. The introduction of the three-body interaction term in the variational scheme recovers the correct scaling for the two important length scales in the globule - its overall size $R$, and the thermal blob size $\xi_{T}$. Since these two length scales follow very different statistics - Gaussian on length scales $\xi_{T}$, and space filling on length scale $R$ - our approach extends the validity of the uniform expansion method to non-uniform contraction rendering it applicable to polymeric systems with attractive interactions. We present one such application by studying the Rayleigh instability of polyelectrolyte globules in poor solvents. At a critical fraction of charged monomers, $f_c$, along the chain backbone, we observe a clear indication of a first-order transition from a globular state at small $f$, to a stretched state at large $f$; in the intermediate regime the bistable equilibrium between these two states shows the existence of a pearl-necklace structure.
Chains in critical fluids and nanopores
Amina Negadi,Arti Dua,Thomas A. Vigis
Physics , 2004,
Abstract: The conformational behavior of a polymer in a critical binary solvent confined in a porous medium is studied. The size of the polymer in bulk, which is mainly governed by the correlation length of the solvent density fluctuations, depends on the proximity to the critical point of the binary mixture. We find that in contrast to the bulk behavior, the conformational properties of the polymer in a porous medium depends strongly on the pore size. The latter controls the correlation length of the solvent density fluctuations and thus determines the polymer size.
History and Advancement of the Family of Log Periodic Toothed Planer Microstrip Antenna  [PDF]
Arti Vaish, Anita Dalal
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2011, DOI: 10.4236/jemaa.2011.36039
Abstract: This paper presents the family of logarithmically periodic toothed planer antennas. In this the dimensions of the succes-sive sections were increased in geometric progression for a wide bandwidth usage. A band width of 7% for trapezoid toothed, 26% for zigzag toothed and 50% for cross-toothed VSWR < 2 has been obtained from the proposed antennas. Investigations on the gain and radiation characteristics have been carried out. The investigations show that the pro-posed designs not only offers the enhanced bandwidth but also possesses the same characteristics over the desired fre-quency band at same probe feed position.
Increased Renal Methylglyoxal Formation with Down-Regulation of PGC-1α-FBPase Pathway in Cystathionine γ-Lyase Knockout Mice
Ashley A. Untereiner, Arti Dhar, Jianghai Liu, Lingyun Wu
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0029592
Abstract: We have previously reported that hydrogen sulfide (H2S), a gasotransmitter and vasodilator has cytoprotective properties against methylglyoxal (MG), a reactive glucose metabolite associated with diabetes and hypertension. Recently, H2S was shown to up-regulate peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α, a key gluconeogenic regulator that enhances the gene expression of the rate-limiting gluconeogenic enzyme, fructose-1,6-bisphosphatase (FBPase). Thus, we sought to determine whether MG levels and gluconeogenic enzymes are altered in kidneys of 6–22 week-old cystathionine γ-lyase knockout (CSE-/-; H2S-producing enzyme) male mice. MG levels were determined by HPLC. Plasma glucose levels were measured by an assay kit. Q-PCR was used to measure mRNA levels of PGC-1α and FBPase-1 and -2. Coupled-enzymatic assays were used to determine FBPase activity, or triosephosphate levels. Experimental controls were either age-matched wild type mice or untreated rat A-10 cells. Interestingly, we observed a significant decrease in plasma glucose levels along with a significant increase in plasma MG levels in all three age groups (6–8, 14–16, and 20–22 week-old) of the CSE-/- mice. Indeed, renal MG and triosephosphates were increased, whereas renal FBPase activity, along with its mRNA levels, were decreased in the CSE-/- mice. The decreased FBPase activity was accompanied by lower levels of its product, fructose-6-phosphate, and higher levels of its substrate, fructose-1,6-bisphosphate in renal extracts from the CSE-/- mice. In agreement, PGC-1α mRNA levels were also significantly down-regulated in 6-22 week-old CSE-/- mice. Furthermore, FBPase-1 and -2 mRNA levels were reduced in aorta tissues from CSE-/- mice. Administration of NaHS, a H2S donor, increased the gene expression of PGC-1α and FBPase-1 and -2 in cultured rat A-10 cells. In conclusion, overproduction of MG in CSE-/- mice is due to a H2S-mediated down-regulation of the PGC-1α-FBPase pathway, further suggesting the important role of H2S in the regulation of glucose metabolism and MG generation.
Ultra low bending loss equiangular spiral photonic crystal fibers in the terahertz regime
Arti Agrawal,N. Kejalakshmy,M. Uthman,B. M. A. Rahman
AIP Advances , 2012, DOI: 10.1063/1.4726055
Abstract: An Equiangular Spiral Photonic Crystal Fiber (ES-PCF) design in Topas for use in the Terahertz regime is presented. The design shows ultra low bending loss and very low confinement loss compared to conventional Hexagonal PCF (H-PCF). The ES-PCF has excellent modal confinement properties, together with several parameters to allow the optimization of the performance over a range of important characteristics. A full vector Finite Element simulation has been used to characterize the design which can be fabricated by a range of techniques including extrusion and drilling.
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