Effects of receptor tyrosine kinase inhibitors on VEGF165a- and VEGF165b-stimulated gene transcription in HEK-293 cells expressing human VEGFR2

BACKGROUND AND PURPOSE: Receptor tyrosine kinase inhibitors (RTKIs) targeted at VEGF receptor 2 (VEGFR2) have proved to be attractive approaches to cancer therapy based on their ability to reduce angiogenesis. Here we have undertaken a quantitative analysis of the interaction of RTKIs and two VEGF splice variants, VEGF165a and VEGF165b, with VEGFR2 by studying nuclear factor of activated T-cells (NFAT) reporter gene activity in live HEK-293 cells. EXPERIMENTAL APPROACH: HEK-293 cells expressing the human VEGFR2 and a firefly luciferase reporter gene regulated by an NFAT response element were used for quantitative analysis of the effect of RTKIs on VEGF165a- and VEGF165b-stimulated luciferase gene expression. KEY RESULTS: VEGF165a produced a concentration-dependent activation of the NFAT-luciferase reporter gene in living cells that was inhibited in a non-competitive fashion by four different RTKIs (cediranib, pazopanib, sorafenib and vandetanib). The potency obtained for each RTKI from this analysis was similar to those obtained in binding studies using purified VEGFR2 kinase domains. VEGF165b was a lower-efficacy agonist of the NFAT-luciferase response when compared with VEGF165a. Analysis of the concentration–response data using the operational model of agonism indicated that both VEGF165 isoforms had similar affinity for VEGFR2. CONCLUSIONS AND IMPLICATIONS: Quantitative pharmacological analysis of the interaction of VEGF165 isoforms and RTKIs with VEGFR2 in intact living cells has provided important insights into the relative affinity and efficacy of VEGF165a and VEGF165b for activation of the calcineurinNFAT signalling pathway by this tyrosine kinase receptor

Editorial Special Issue on Enhancement Algorithms, Methodologies and Technology for Spectral Sensing

The paper is an editorial issue on enhancement algorithms, methodologies and technology for spectral sensing and serves as a valuable and useful reference for researchers and technologists interested in the evolving state-of-the-art and/or the emerging science and technology base associated with spectral-based sensing and monitoring problem. This issue is particularly relevant to those seeking new and improved solutions for detecting chemical, biological, radiological and explosive threats on the land, sea, and in the air

Long‐term cardiovascular effects of vandetanib and pazopanib in normotensive rats

Vandetanib and pazopanib are clinically available, multi‐targeted inhibitors of vascular endothelial growth factor (VEGF) and platelet‐derived growth factor (PDGF) receptor tyrosine kinases. Short‐term VEGF receptor inhibition is associated with hypertension in 15%‐60% of patients, which may limit the use of these anticancer therapies over the longer term. To evaluate the longer‐term cardiovascular implications of treatment, we investigated the “on”‐treatment (21 days) and “off”‐treatment (10 days) effects following daily administration of vandetanib, pazopanib, or vehicle, in conscious rats. Cardiovascular variables were monitored in unrestrained Sprague‐Dawley rats instrumented with radiotelemetric devices. In Study 1, rats were randomly assigned to receive either daily intraperitoneal injections of vehicle (volume 0.5 mL; n = 5) or vandetanib 25 mg/kg/day (volume 0.5 mL; n = 6). In Study 2, rats received either vehicle (volume 0.5 mL; n = 4) or pazopanib 30 mg/kg/day (volume 0.5 mL; n = 7), dosed once every 24 hours for 21 days. All solutions were in 2% Tween, 5% propylene glycol in 0.9% saline solution. Vandetanib caused sustained increases in mean arterial pressure (MAP), systolic blood pressure (SBP), and diastolic blood pressure (DBP) compared to baseline and vehicle. Vandetanib also significantly altered the circadian cycling of MAP, SBP, and DBP. Elevations in SBP were detectable 162 hours after the last dose of vandetanib. Pazopanib also caused increases in MAP, SBP, and DBP. However, compared to vandetanib, these increases were of slower onset and a smaller magnitude. These data suggest that the cardiovascular consequences of vandetanib and pazopanib treatment are sustained, even after prolonged cessation of drug treatment

Clinicopathological characteristics of histiocytic sarcoma affecting the central nervous system in dogs.

BackgroundHistiocytic sarcoma affecting the central nervous system (CNS HS) in dogs may present as primary or disseminated disease, often characterized by inflammation. Prognosis is poor, and imaging differentiation from other CNS tumors can be problematic.ObjectiveTo characterize the clinicopathological inflammatory features, breed predisposition, and survival in dogs with CNS HS.AnimalsOne hundred two dogs with HS, 62 dogs with meningioma.MethodsRetrospective case series. Records were reviewed for results of cerebrospinal fluid (CSF) analysis, CBC, treatment, and outcome data.ResultsPredisposition for CNS HS was seen in Bernese Mountain Dogs, Golden Retrievers, Rottweilers, Corgis, and Shetland Sheepdogs (P ≤ .001). Corgis and Shetland Sheepdogs had predominantly primary tumors; Rottweilers had exclusively disseminated tumors. Marked CSF inflammation was characteristic of primary rather than disseminated HS, and neoplastic cells were detected in CSF of 52% of affected dogs. Increased neutrophil to lymphocyte ratios were seen in all groups relative to controls (P <.008) but not among tumor subtypes. Definitive versus palliative treatment resulted in improved survival times (P < .001), but overall prognosis was poor.Conclusions and clinical importanceClinicopathological differences between primary and disseminated HS suggest that tumor biological behavior and origin may be different. Corgis and Shetland Sheepdogs are predisposed to primary CNS HS, characterized by inflammatory CSF. High total nucleated cell count and the presence of neoplastic cells support the use of CSF analysis as a valuable diagnostic test. Prognosis for CNS HS is poor, but further evaluation of inflammatory mechanisms may provide novel therapeutic opportunities

Spatial characterization, resolution, and volumetric change of coastal dunes using airborne LIDAR: Cape Hatteras

ABSTRACT The technological advancement in topographic mapping known as airborne Light Detection and Ranging (LIDAR) allows researchers to gather highly accurate and densely sampled coastal elevation data at a rapid rate. The problem is to determine the optimal resolutions at which to represent coastal dunes for volumetric change analysis. This study uses digital elevation models (DEM) generated from LIDAR data and spatial statistics to better understand dune characterization at a series of spatial resolutions. The LIDAR data were collected jointly by the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the U.S. Geological Survey (USGS). DEMs of two study sites (100×200 m) located in Cape Hatteras National Seashore, North Carolina were generated using a raster-based geographic information system (GIS). Changes in the dune volume were calculated for a 1-year period of time (Fall 1996(Fall -1997 at grid cell resolutions ranging from 1×1 to 20×20 m. Directional statistics algorithms were used to calculate local variance and characterize topographic complexity. Data processing was described in detail in order to provide an introduction to working with LIDAR data in a GIS. Results from these study sites indicated that a 1-2 m resolution provided the most reliable representation of coastal dunes on Cape Hatteras and most accurate volumetric change measurements. Results may vary at other sites and at different spatial extents, but the methods developed here can be applied to other locations to determine the optimum resolutions at which to represent and characterize topography using common GIS and database software

Use of a new proximity assay (NanoBRET) to investigate the ligand binding characteristics of three fluorescent ligands to the human β1-adrenoceptor expressed in HEK-293 cells

Previous research has indicated that allosteric interactions across the dimer interface of β1-adrenoceptors may be responsible for a secondary low affinity binding conformation. Here we have investigated the potential for probe dependence, in the determination of antagonist pKi values at the human β1-adenoceptor, which may result from such allosterism interactions. Three fluorescent β1-adrenoceptor ligands were used to investigate this using bioluminescence energy transfer (BRET) between the receptor-bound fluorescent ligand and the N-terminal NanoLuc tag of a human β1-adrenoceptor expressed in HEK 293 cells (NanoBRET). This proximity assay showed high affinity specific binding to the NanoLuc-β1-adrenoceptor with each of the three fluorescent ligands yielding KD values of 87.1 ± 10nM (n=8), 38.1 ± 12nM (n=7), 13.4 ± 2nM (n=14) for propranolol-Peg8-BY630, propranolol-3(Ala-Ala)-BY630 and CGP-12177- TMR respectively. Parallel radioligand-binding studies with 3H-CGP12177 and TIRF microscopy, to monitor NanoLuc bioluminescence, confirmed a high cell surface expression of the NanoLuc- 31-adrenoceptor in HEK 293 cells (circa 1500 fmol.mg protein-1). Following a 1h incubation with fluorescent ligands and β1-adrenoceptor competing antagonists, there were significant differences (p < 0.001) in the pKi values obtained for CGP20712a and CGP 12177 with the different fluorescent ligands and 3H-CGP 12177. However, increasing the incubation time to 2h removed these significant differences. The data obtained show that the NanoBRET assay can be applied successfully to study ligand-receptor interactions at the human β1-adrenoceptor. However, the study also emphasizes the importance of ensuring that both the fluorescent and competing ligands are in true equilibrium before interpretations regarding probe dependence can be made