Search results for "Signal"
showing 10 items of 6924 documents
Pigment epithelium-derived factor is a niche signal for neural stem cell renewal.
2006
Adult stem cells are characterized by self-renewal and multilineage differentiation, and these properties seem to be regulated by signals from adjacent differentiated cell types and by extracellular matrix molecules, which collectively define the stem cell "niche." Self-renewal is essential for the lifelong persistence of stem cells, but its regulation is poorly understood. In the mammalian brain, neurogenesis persists in two germinal areas, the subventricular zone (SVZ) and the hippocampus, where continuous postnatal neuronal production seems to be supported by neural stem cells (NSCs). Here we show that pigment epithelium-derived factor (PEDF) is secreted by components of the murine SVZ a…
Sustained activation of mTOR pathway in embryonic neural stem cells leads to development of tuberous sclerosis complex-associated lesions
2011
SummaryTuberous Sclerosis Complex (TSC) is a multisystem genetic disorder characterized by hamartomatous neurological lesions that exhibit abnormal cell proliferation and differentiation. Hyperactivation of mTOR pathway by mutations in either the Tsc1 or Tsc2 gene underlies TSC pathogenesis, but involvement of specific neural cell populations in the formation of TSC-associated neurological lesions remains unclear. We deleted Tsc1 in Emx1-expressing embryonic telencephalic neural stem cells (NSCs) and found that mutant mice faithfully recapitulated TSC neuropathological lesions, such as cortical lamination defects and subependymal nodules (SENs). These alterations were caused by enhanced gen…
Chromatin modifiers and recombination factors promote a telomere fold-back structure, that is lost during replicative senescence.
2020
Telomeres have the ability to adopt a lariat conformation and hence, engage in long and short distance intra-chromosome interactions. Budding yeast telomeres were proposed to fold back into subtelomeric regions, but a robust assay to quantitatively characterize this structure has been lacking. Therefore, it is not well understood how the interactions between telomeres and non-telomeric regions are established and regulated. We employ a telomere chromosome conformation capture (Telo-3C) approach to directly analyze telomere folding and its maintenance in S. cerevisiae. We identify the histone modifiers Sir2, Sin3 and Set2 as critical regulators for telomere folding, which suggests that a dis…
Design of temperature control system using conventional PID and Intelligent Fuzzy Logic controller
2015
In this paper, we present the design of temperature control for industrial heat treating furnace by using Intelligent Fuzzy Logic and PID controllers. Temperature control is important in heating processes as it can disqualify materials in terms of their physical properties when not well performed. Obviously PID temperature controller is the most used in industries to control non-linear processes. Consequently, it has been found that the output response from Fuzzy Logic is very accurate in terms of overshoot and steady state error when compared to that of PID. Moreover, both temperature controllers are modeled and simulated using MATLAB software.
Terahertz four-wire waveguides for broadband signal processing and multiplexing
2022
In this work, we introduce a versatile metal-wire waveguide geometry, namely a four-wire waveguide, which is capable of sustaining two independent and orthogonally polarized fundamental modes, thus acting as a broadband polarization-division multiplexer. By integrating multiscale-structured grooves into the wires of such a waveguide, we demonstrate the independent manipulation of polarization-division terahertz signals.
Broadband Terahertz Signal Processing and Multiplexing with Four-wire Waveguides
2022
We demonstrate a new waveguide geometry, namely a four-wire waveguide, which acts as a terahertz polarization-division multiplexer and a novel platform to realize versatile signal-processing functionalities into independent channels over a broadband terahertz frequency range.
Biomechanics of human ascending aorta and aneurysm rupture risk assessment
2021
Ascending aortic aneurysms (AsAA) and aortic dissections are life-threatening cardiovascular diseases. The main criteria for determining surgical intervention of AsAA are the maximum diameter or the increasing annual rate of the aneurysm. The mortality of the untreated aortic dissection can be 21% to 74%, depending on the delay of hospital admission.Our study aims to characterize the biomechanical properties of the ascending aorta and propose a patient-specific approach to assess the risks of rupture. The purpose of this PhD work is multifold.On the one hand, biaxial tensile tests were performed on AsAA samples obtained from one hundred patients with surgery of AsAA. The impact on the diffe…
Cytotoxic phytochemicals from the crude extract of Tetrapleura tetraptera fruits towards multi-factorial drug resistant cancer cells.
2020
Abstract Ethnopharmacological relevance Tetrapleura tetraptera is an African medicinal spice used in traditional medicine to treat several ailments including cancer. Aim of the study The present study was designed to evaluate the cytotoxicity of the dichloromethane-methanol (1:1) extract of the fruits of Tetrapleura tetraptera (TTF) and its constituents: (3R, 4S)-3,4-dimethyloxetan-2-one (1), luteolin (2), stigmasterol (4), 3-O-[6′-O-undecanoyl-β-D-glucopyranosyl]stigmasterol (6), olean-12-en-3-β-O-D-glucopyranoside (7), 3-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosylurs-12-en-28-oic acid (8), 3-O-β-D-glucopyranosyl-(1 → 3)-β-D-glucopyranosyl-27-hydroxyolean-12-ene-28-oic acid (9), methyl…
2-Hydroxyoleic Acid Induces ER Stress and Autophagy in Various Human Glioma Cell Lines
2012
Background: 2-Hydroxyoleic acid is a synthetic fatty acid with potent anti-cancer activity which does not induce undesired side effects. However, the molecular and cellular mechanisms by which this compound selectively kills human glioma cancer cells without killing normal cells is not fully understood. The present study was designed to determine the molecular bases underlying the potency against 1321N1, SF-767 and U118 human glioma cell lines growth without affecting non cancer MRC-5 cells. Methodology/Principal Findings: The cellular levels of endoplasmic reticulum (ER) stress, unfolded protein response (UPR) and autophagy markers were determined by quantitative RT-PCR and immunoblotting …
Modulation of intracellular calcium concentrations and T cell activation by prickly pear polyphenols.
2004
Opuntia ficus indica (prickly pear) polyphenolic compounds (OFPC) triggered an increase in [Ca2+]i in human Jurkat T-cell lines. Furthermore, OFPC-induced rise in [Ca2+]i was significantly curtailed in calcium-free buffer (0% Ca2+) as compared to that in 100% Ca2+ medium. Preincubation of cells with tyrphostin A9, an inhibitor of Ca2+ release-activated Ca2+ (CRAC) channels, significantly diminished the OFPC-induced sustained response on the increases in [Ca2+]i. Lanthanum and nifedipine, the respective inhibitors of voltage-dependent and L-type calcium channels, failed to curtail significantly the OFPC-induced calcium response. As OFPC still stimulated increases in [Ca2+]i in 0% Ca2+ medium…