Kinetic analysis of PI3K reactions with fluorescent PIP2 derivatives

PI3K signaling plays important roles in cell differentiation, proliferation, and migration. Increased mutations and expression levels of PI3K are hallmarks for the development of certain cancers. Pharmacological targeting of PI3K activity has also been actively pursued as a novel cancer therapeutic. Consequently, measurement of PI3K activity in different cell types or patient samples holds the promise as being a novel diagnostic tool. However, the direct measurement of cellular PI3K activity has been a challenging task. We report here the characterization of two fluorescent PIP2 derivatives as reporters for PI3K enzymatic activity. The reporters are efficiently separated from their corresponding PI3K enzymatic products through either thin layer chromatography (TLC) or capillary electrophoresis (CE), and can be detected with high sensitivity by fluorescence. The biophysical and kinetic properties of the two probes are measured, and their suitability to characterize PI3K inhibitors is explored. Both probes show similar capacity as PI3K substrates for inhibitor characterization, yet also possess distinct properties that may suggest their different applications. These characterizations have laid the groundwork to systematically measure cellular PI3K activity, and have the potential to generate molecular fingerprints for diagnostic and therapeutic applications

Universal sublinear resistivity in vanadium kagome materials hosting charge density waves

The recent discovery of a charge density (CDW) state in ScV$_6$Sn$_6$ at $T_{\textrm{CDW}}$ = 91 K offers new opportunities to understand the origins of electronic instabilities in topological kagome systems. By comparing to the isostructural non-CDW compound LuV$_6$Sn$_6$, we unravel interesting electrical transport properties in ScV$_6$Sn$_6$, above and below the charge ordering temperature. We observed that by applying a magnetic field along the $a$ axis, the temperature behavior of the longitudinal resistivity in ScV$_6$Sn$_6$ changes from metal-like to insulator-like above the CDW transition. We show that in the charge ordered state ScV$_6$Sn$_6$ follows the Fermi liquid behavior while above that, it transforms into a non-Fermi liquid phase in which the resistivity varies sublinearly over a broad temperature range. The sublinear resistivity, which scales by $T^{3/5}$ is a common feature among other vanadium-containing kagome compounds exhibiting CDW states such as KV$_3$Sb$_5$, RbV$_3$Sb$_5$, and CsV$_3$Sb$_5$. By contrast, the non-Fermi liquid behavior does not occur in LuV$_6$Sn$_6$. We explain the $T^{3/5}$ universal scaling behavior from the Coulomb scattering between Dirac electrons and Van Hove singularities; common features in the electronic structure of kagome materials. Finally, we show anomalous Hall-like behavior in ScV$_6$Sn$_6$ below $T_{\textrm{CDW}}$, which is absent in the Lu compound. Comparing the transport properties of ScV$_6$Sn$_6$ and LuV$_6$Sn$_6$ is valuable to highlight the impacts of the unusual CDW in the Sc compound.Comment: 12 pages, 6 figures. Power law behavior of resistivity as a function temperature is modified and theoretical explanation is added in the second versio

"Extraordinary" Phase Transition Revealed in a van der Waals Antiferromagnet

While the surface-bulk correspondence has been ubiquitously shown in topological phases, the relationship between surface and bulk in Landau-like phases is much less explored. Theoretical investigations since 1970s for semi-infinite systems have predicted the possibility of the surface order emerging at a higher temperature than the bulk, clearly illustrating a counterintuitive situation and greatly enriching phase transitions. But experimental realizations of this prediction remain missing. Here, we demonstrate the higher-temperature surface and lower-temperature bulk phase transitions in CrSBr, a van der Waals (vdW) layered antiferromagnet. We leverage the surface sensitivity of electric dipole second harmonic generation (SHG) to resolve surface magnetism, the bulk nature of electric quadrupole SHG to probe bulk spin correlations, and their interference to capture the two magnetic domain states. Our density functional theory calculations show the suppression of ferromagnetic-antiferromagnetic competition at the surface responsible for this enhanced surface magnetism. Our results not only show unexpected, richer phase transitions in vdW magnets, but also provide viable ways to enhance magnetism in their 2D form

Estrogen regulation of TRPM8 expression in breast cancer cells

<p>Abstract</p> <p>Background</p> <p>The calcium-permeable cation channel TRPM8 (melastatin-related transient receptor potential member 8) is over-expressed in several cancers. The present study aimed at investigating the expression, function and potential regulation of TRPM8 channels by ER alpha (estrogen receptor alpha) in breast cancer.</p> <p>Methods</p> <p>RT-PCR, Western blot, immuno-histochemical, and siRNA techniques were used to investigate TRPM8 expression, its regulation by estrogen receptors, and its expression in breast tissue. To investigate the channel activity in MCF-7 cells, we used the whole cell patch clamp and the calcium imaging techniques.</p> <p>Results</p> <p>TRPM8 channels are expressed at both mRNA and protein levels in the breast cancer cell line MCF-7. Bath application of the potent TRPM8 agonist Icilin (20 μM) induced a strong outwardly rectifying current at depolarizing potentials, which is associated with an elevation of cytosolic calcium concentration, consistent with established TRPM8 channel properties. RT-PCR experiments revealed a decrease in TRPM8 mRNA expression following steroid deprivation for 48 and 72 hours. In steroid deprived medium, addition of 17-beta-estradiol (E₂, 10 nM) increased both TRPM8 mRNA expression and the number of cells which respond to Icilin, but failed to affect the Ca²⁺entry amplitude. Moreover, silencing ERα mRNA expression with small interfering RNA reduced the expression of TRPM8. Immuno-histochemical examination of the expression of TRPM8 channels in human breast tissues revealed an over-expression of TRPM8 in breast adenocarcinomas, which is correlated with estrogen receptor positive (ER⁺) status of the tumours.</p> <p>Conclusion</p> <p>Taken together, these results show that TRPM8 channels are expressed and functional in breast cancer and that their expression is regulated by ER alpha.</p

Imaging reservoir quality of Knurr and Stø Formations in the Hammerfest Basin and Ringvassøy-Loppa Fault Complex, Norwegian Barents Sea

The Barents Sea is a prospective area in terms of hydrocarbon resources with high ratio of discovery wells. This study focuses on reservoir quality of two sandstone reservoirs of Knurr and Stø Formations in the Hammerfest Basin and Ringvassøy-Loppa Fault Complex in the Norwegian Barents Sea. The study methods include petrophysics analysis, rock physics diagnostics and AVO modelling. Seven exploration wells from the study area are analysed to investigate the reservoir quality of two target reservoirs. The studied reservoir sandstones are buried at different depth levels from approximately 1400 m to 3300 m (RKB). Therefore, this database provides a perfect profile for sandstone compaction and diagenetic studies. A comparison of Vp-depth trends in studied wells and published Vp-depth trends for normally subsided basins shows that the Vp in the study area are much higher than expected. The calculated average porosity values of the reservoirs are much lower than published porosity-depth trends. Regional uplift and erosion is attributed as the main reason for these anomalous values. The estimated average uplift in the study area is about 900 m. The exhumation decrease to the north-west direction. After estimation of uplift, the present depth is corrected to a maximum burial depth. New depth data are subsequently used to calculate maximum burial temperatures for the reservoirs. The maximum temperatures show that the sediments have experienced much higher thermal exposures than what is interpolated from bottom hole temperatures. All the reservoirs in the studied wells are within the zone of chemical compaction. It is clear from petrophysical analysis that the reservoir quality of the Knurr Formation is poorer compared to the Stø Formation. The Knurr Formation is deposited in a submarine fan system while the Stø Formation is deposited in a coastal environment. Different sedimentary environments result in different reservoir parameters, like net-to-gross ratio, shale volume and porosity. Rock physics templates work well for estimating quartz cement content and for distinguishing different lithologies and pore fluids. Even the shallowest buried sandstones (around 1200 meters below sea floor) in well 7119/12-2 contain cements between the grains according to rock physics diagnostic results. This is also confirmed by published literatures. Secondary porosity is also common in the studied wells. A clear trend of rock properties with increasing depth is observed in all of the rock physics templates used. Lamda-Rho versus Mu-Rho cross plot works better than Vp/Vs versus IP cross plot for discriminating the lithology and fluid in the studied wells. Due to the complex compaction and diagenetic history, the shear wave velocity measured in well 7119/12-4 is abnormally high. These high shear wave velocities result false gas effect in rock physics templates (e.g. Vp/Vs versus IP and LMR). The AVO modelling results agree reasonably well with the classical AVO theory. The gas-bearing data points deviate from the background trend at both the top and bottom interfaces of the reservoirs. An impedance inversion with increasing depth is observed in the AVO modelling for the Stø Formation sandstones. With increasing depth, the soft sandstones turn into hard sandstones compared to the overlying shale. The AVO modelling results are sensitive to many factors, like water saturation, wavelet and block size. The measured Vs values in well 7119/12-4 also result false gas effect in AVO modelling

Large Oscillatory Thermal Hall Effect in Kagome Metals

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Dynamics Characteristics of Blast Furnace Shell

Abstract. Finite element method and structural mechanics method are used to study the blast furnace shell modal analysis and the natural frequencies and mode shapes have been calculated. The two methods were compared and validated , and the results provide a theoretical foundation for the anti-vibration capabilities design of blast furnace shell in the future

Research on the Vibration of Rolling Mill

Abstract. In this paper a horizontal vibration problem in strip rolling was studied; dynamic model was established; the mechanism of self-excited vibration was analyzed. The main reason of surface quality of strip is self-excited vibration. A vertical natural frequency and vibration mode of the rolling mill are obtained by finite element method. It lays the theoretic foundation for future researches on rolling mill vibraton

Electrochemiluminescence Imaging for Bioanalysis

International audienc