Search results for "Intrinsic"
showing 10 items of 386 documents
Targeting apoptosis proteins in hematological malignancies
2010
The apoptotic machinery plays a key role in hematopoietic cell homeostasis. Terminally differentiated cells are eliminated, at least in part, by apoptosis, whereas part of the apoptotic machinery, including one or several caspases, is required to go through very specific steps of the differentiation pathways. A number of hematological diseases involve a deregulation of this machinery, which in most cases is a decrease in cell sensitivity to pro-apoptotic signals through over-expression of anti-apoptotic molecules. In some situations however, e.g. in the erythroid lineage of low grade myelodysplastic syndromes, cell sensitivity to apoptosis is increased in a death receptor-dependent manner a…
Cyclooxygenase-2 inhibition induces apoptosis signaling via death receptors and mitochondria in hepatocellular carcinoma.
2006
AbstractInhibition of cyclooxygenase (COX)-2 elicits chemopreventive and therapeutic effects in solid tumors that are coupled with the induction of apoptosis in tumor cells. We investigated the mechanisms by which COX-2 inhibition induces apoptosis in hepatocellular carcinoma (HCC) cells. COX-2 inhibition triggered expression of the CD95, tumor necrosis factor (TNF)-R, and TNF-related apoptosis-inducing ligand (TRAIL)-R1 and TRAIL-R2 death receptors. Addition of the respective specific ligands further increased apoptosis, indicating that COX-2 inhibition induced the expression of functional death receptors. Overexpression of a dominant-negative Fas-associated death domain mutant reduced COX…
Short hydrogen bonds enhance nonaromatic protein-related fluorescence
2021
Significance Intrinsic fluorescence of nonaromatic amino acids is a puzzling phenomenon with an enormous potential in biophotonic applications. The physical origins of this effect, however, remain elusive. Herein, we demonstrate how specific hydrogen bond networks can modulate fluorescence. We highlight the key role played by short hydrogen bonds, present in the protein structure, on the ensuing fluorescence. We provide detailed experimental and molecular evidence to explain these unusual nonaromatic optical properties. Our findings should benefit the design of novel optically active biomaterials for applications in biosensing and imaging.
Die molekularen Konstanten von Polycarbonaten in Lösung
1959
An einer Reihe von fraktionierten Polycarbonaten werden in zwei Losungsmitteln die Diffusions- und Sedimentationskonstanten, die Viskositatszahlen, die osmotischen Drucke sowic die Lichtstreuung gemessen. Daraus wird eine Eichkurve zur viskosimetrischen Molekulargewichtsbestimmung abgeleitet und aus einem Vergleich der verschidednen Mittelwerte des Molekulargewichts die Uneinheitlichkeit der Fraktionen abgeschatzt. Aus den Reibungs-und Lichtstreuungsdaten werden die Knauelabmessungen berchnot und mit Hilfe der gemessenen zweiten Virialkoeffizientin auf das indifferente Losunmittal reduziert. Die Volumbeanspruchung der Polycarbonatmolekule in Losung ist groser als die vergleichbarer Polyviny…
Vorschlag zur Unterscheidung der 2 Größen: „Grenzviskositätszahl” u. „konventionelle Viskositätszahl”
1954
Fur viskosimetrische Molekulargewichtsbestimmungen ist es nicht notig, die Viskositatszahl auf den Geschwindigkeitsgradienten 0 zu extrapolieren. Es wird empfohlen, die Viskositatszahl derart zu normieren, das zur Messung bestimmte Kapillarenradien verwendet werden. Dadurch wird jedem Losungsmittel ein bestimmter Gradient (i. A. zwischen 0,5 und 1,5.103 sec−1 zugeordnet, und damit ist auch fur jedes in diesem Losungsmittel gemessene Polymere die „konventionelle Viskositatszahl” eindeutig und reproduzierbar festgelegt. Eichkurven zur viskosimetrischen Molekulargewichtsbestimmung sollten auf die konventionelle Viskositatszahl bezogen werden. Diese weicht nur bei hohen Polymeren von der Grenzv…
Molekulargewichtsbestimmungen an verschieden scharf fraktionierten polymethacrylsäuremethylestern
1954
Aus drei Polymethacrylsauremethylestern, deren Molekulargewichte bei ungefahr 35 000, 500 000 und 8 000 000 lagen, wurden durch fortgesetzte Fraktionierung Praparate von sehr verschiedener Einheitlichkeit hergestellt. Das Molekulargewicht der einzelnen Fraktionen wurde in der Ultrazentrifuge gemessen, sowie die zugehorige Viskositatszahl in Benzol bestimmt. Es zeigt sich, das der Einflus der Einheitlichkeit fur die Beziehung zwischen Polymerisationsgrades und Viskositatszahl gering ist, falls man den Gewichtsdurchschnitt des Molekulargewichtes mist. Die bei diesen Versuchen gewonnenen Sedimentations- und Diffusionskurven werden im Hinblick auf die aus ihnen zu berechnenden Verteilungskurven…
IM30 IDPs form a membrane protective carpet upon super-complex disassembly
2020
AbstractMembers of thephage shock protein A(PspA) family, including theinner membrane-associated protein of 30 kDa(IM30), are suggested to stabilize stressed cellular membranes. Furthermore, IM30 is essential in thylakoid membrane-containing chloroplasts and cyanobacteria, where it is involved in membrane biogenesis and/or remodeling. While it is well known that PspA and IM30 bind to membranes, the mechanism of membrane stabilization is still enigmatic. Here we report that ring-shaped IM30 super-complexes disassemble on membranes, resulting in formation of a membrane-protecting protein carpet. Upon ring dissociation, the C-terminal domain of IM30 unfolds, and the protomers self-assemble on …
Preferential solvation of a dicyanate ester monomer and poly(sulfone) in different organic solvents by size-exclusion chromatography.
2002
Preferential solvation parameters A in the ternary systems solvent (1) -monomer (2) -polymer (3) were determined as a tool to measure the compatibility between the cyanate ester monomer Arocy B10 and poly(sulfone), PSF, in the presence of three organic solvents: tetrahydrofuran, dimethylformamide and dicloromethane. The A parameter was measured by size-exclusion chromatography at different monomer-to-polymer ratios. The quantitative evaluation was rigorously made at polymer-diluted conditions. PSF was found to be preferentially solvated by the monomer. Concerning the solvent used, systems containing tetrahydrofuran showed the strongest solvation, the lowest A values being those obtained in …
Fast Matrix Multiplication
2015
Until a few years ago, the fastest known matrix multiplication algorithm, due to Coppersmith and Winograd (1990), ran in time O(n2.3755). Recently, a surge of activity by Stothers, Vassilevska-Williams, and Le~Gall has led to an improved algorithm running in time O(n2.3729). These algorithms are obtained by analyzing higher and higher tensor powers of a certain identity of Coppersmith and Winograd. We show that this exact approach cannot result in an algorithm with running time O(n2.3725), and identify a wide class of variants of this approach which cannot result in an algorithm with running time $O(n^{2.3078}); in particular, this approach cannot prove the conjecture that for every e > 0, …
Effect of kind and content of organo-modified clay on properties of PET nanocomposites
2011
In this work we report the properties of nanocomposite based on PET with two different samples of organically modified montmorillonites. In particular, we studied the effect of the filler concentration on morphology, rheology, and mechanical performance, focusing our attention on the effect of the degradation phenomena of the clay modifiers. The results indicate that at low clay level the morphology achieved is mainly intercalated. On increasing the filler level, coalescence and/or bad defragmentation phenomena induce a coarser morphology, as confirmed by XRD, SEM, and TEM observations. When a more polar organic modifier is used to modify the clay, the particle adhesion and distribution is …