Vascular contributions to cognitive impairment and dementia including Alzheimer's disease

AbstractScientific evidence continues to demonstrate the linkage of vascular contributions to cognitive impairment and dementia such as Alzheimer's disease. In December, 2013, the Alzheimer's Association, with scientific input from the National Institute of Neurological Disorders and Stroke and the National Heart, Lung and Blood Institute from the National Institutes of Health, convened scientific experts to discuss the research gaps in our understanding of how vascular factors contribute to Alzheimer's disease and related dementia. This manuscript summarizes the meeting and the resultant discussion, including an outline of next steps needed to move this area of research forward

The androgen receptor can signal through Wnt/β-Catenin in prostate cancer cells as an adaptation mechanism to castration levels of androgens

<p>Abstract</p> <p>Background</p> <p>A crucial event in Prostate Cancer progression is the conversion from a hormone-sensitive to a hormone-refractory disease state. Correlating with this transition, androgen receptor (AR) amplification and mutations are often observed in patients failing hormonal ablation therapies. β-Catenin, an essential component of the canonical Wnt signaling pathway, was shown to be a coactivator of the AR signaling in the presence of androgens. However, it is not yet clear what effect the increased levels of the AR could have on the Wnt signaling pathway in these hormone-refractory prostate cells.</p> <p>Results</p> <p>Transient transfections of several human prostate cancer cell lines with the AR and multiple components of the Wnt signaling pathway demonstrate that the AR overexpression can potentiate the transcriptional activities of Wnt/β-Catenin signaling. In addition, the simultaneous activation of the Wnt signaling pathway and overexpression of the AR promote prostate cancer cell growth and transformation at castration levels of androgens. Interestingly, the presence of physiological levels of androgen or other AR agonists inhibits these effects. These observations are consistent with the nuclear co-localization of the AR and β-Catenin shown by immunohistochemistry in human prostate cancer samples. Furthermore, chromatin immunoprecipitation assays showed that Wnt3A can recruit the AR to the promoter regions of Myc and Cyclin D1, which are well-characterized downstream targets of the Wnt signalling pathway. The same assays demonstrated that the AR and β-Catenin can be recruited to the promoter and enhancer regions of a known AR target gene PSA upon Wnt signaling. These results suggest that the AR is promoting Wnt signaling at the chromatin level.</p> <p>Conclusion</p> <p>Our findings suggest that the AR signaling through the Wnt/β-Catenin pathway should be added to the well established functional interactions between both pathways. Moreover, our data show that via this interaction the AR could promote prostate cell malignancy in a ligand-independent manner.</p

Profiling phlorotannins in brown Macroalgae by liquid chromatography-high resolution mass spectronmetry

Introduction \u2013 Phlorotannins, phenolic compounds produced exclusively by Phaeophyceae (brown algae), have recently been associated with a wide variety of bene\ufb01cial bioactivities. Several studies have measured the total phenolic content in extracts from various species, but little characterisation of individual phlorotannin components has been demonstrated. Objective \u2013 The purpose of this study was to develop a liquid chromatography\u2013mass spectrometry (LC-MS) based method for rapid pro\ufb01ling of phlorotannins in brown algae. Methodology \u2013 Phlorotannin-enriched extracts from \ufb01ve phaeophyceaen species were analysed by ultrahigh-pressure liquid chromatography (UHPLC) operating in hydrophilic interaction liquid chromatography (HILIC) mode combined with high resolution mass spectrometry (HRMS). The method was optimised using an extract of Fucus vesiculosus; separation was achieved in less than 15 min. The basic mobile phase enhanced negative-ion electrospray ionisation (ESI), and generated multiply charged ions that allowed detection of high molecular weight phlorotannins. Results \u2013 The phlorotannin pro\ufb01les of Pelvetia canaliculata, Fucus spiralis, F. vesiculosus, Ascophyllum nodosum and Saccharina longicruris differed signi\ufb01cantly. Fucus vesiculosus yielded a high abundance of low molecular weight (< 1200 Da) phlorotannins, while P. canaliculata exhibited a more evenly distributed pro\ufb01le, with moderate degrees of polymerisation ranging from 3 to 49. HRMS enabled the identi\ufb01cation of phlorotannins with masses up to 6000 Da using a combination of accurate mass and \ub9\ub3C isotopic patterns. Conclusion \u2013 The UHPLC-HRMS method described was successful in rapidly pro\ufb01ling phlorotannins in brown seaweeds based on their degree of polymerisation. HILIC was demonstrated to be an effective separation mode, particularly for low molecular weight phlorotannins.Peer reviewed: YesNRC publication: Ye

Functional Comparisons of Visual Arrestins in Rod Photoreceptors of Transgenic Mice

PURPOSE. To examine the biochemical characteristics of rod and cone arrestin with respect to their ability to quench the activity of light-activated rhodopsin in transgenic mice. METHODS. The mouse rod opsin promoter was used to drive expression of mouse cone arrestin in rod photoreceptor cells of rod arrestin knockout (arr1Ϫ/Ϫ) mice. Suction electrode recordings from single rods were performed to investigate cone arrestin&apos;s ability to quench the catalytic activity of lightactivated rhodopsin. In addition, the ability of cone arrestin to prevent light-induced retinal damage caused by prolonged activation of the phototransduction cascade was assessed. RESULTS. Two independent lines of transgenic mice were obtained that expressed cone arrestin in rod photoreceptors, and each was bred into the arr1Ϫ/Ϫ background. Flash responses measured by suction electrode recordings showed that cone arrestin reduced signaling from photolyzed rhodopsin but was unable to quench its activity completely. Consistent with this observation, expression of mouse cone arrestin conferred dose-dependent protection against photoreceptor cell death caused by low light exposure to arr1Ϫ/Ϫ retinas, but did not appear to be as effective as rod arrestin. CONCLUSIONS. Cone arrestin can partially substitute for rod arrestin in arr1Ϫ/Ϫ rods, offering a degree of protection from light-induced damage and increasing the extent of rhodopsin deactivation in response to flashes of light. Although earlier work has shown that rod arrestin can bind and deactivate cone pigments efficiently, the results suggest that cone arrestin binds light-activated, phosphorylated rhodopsin less efficiently than does rod arrestin in vivo. These results suggest that the structural requirements for high-affinity binding are fundamentally distinct for rod and cone arrestins. (Invest Ophthalmol Vis Sci

Effect of G Protein–Coupled Receptor Kinase 1 (Grk1) Overexpression on Rod Photoreceptor Cell Viability

Grk1, or rhodopsin kinase, has been known for its critical function in visual pigment deactivation in photoreceptors, with its deficiency leading to photoreceptor dysfunction and light-induced photoreceptor cell death. This study was an investigation of whether and how enhancing pigment phosphorylation might affect photoreceptor viability

The preparation of certified calibration solutions for azaspiracid-1, -2, and -3, potent marine biotoxins found in shellfish

The production and certification of a series of azaspiracid (AZA) calibration solution reference materials is described. Azaspiracids were isolated from contaminated mussels, purified by preparative liquid chromatography and dried under vacuum to the anhydrous form. The purity was assessed by liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. The final concentration of each AZA in a CD 3OH stock solution was determined by quantitative NMR spectroscopy. This solution was then diluted very accurately in degassed, high purity methanol to a concentration of 1.47 \ub1 0.08 \u3bcmol/L for CRM-AZA1, 1.52 \ub1 0.05 \u3bcmol/L for CRM-AZA2, and 1.37 \ub1 0.13 \u3bcmol/L for CRM-AZA3. Aliquots were dispensed into argon-filled glass ampoules, which were immediately flame-sealed. The calibration solutions are suitable for method development, method validation, calibration of liquid chromatography or mass spectrometry instrumentation and quality control of shellfish monitoring programs.Peer reviewed: YesNRC publication: Ye

The preparation of certified calibration solutions for azaspiracid-1, -2, and -3, potent marine biotoxins found in shellfish

The production and certification of a series of azaspiracid (AZA) calibration solution reference materials is described. Azaspiracids were isolated from contaminated mussels, purified by preparative liquid chromatography and dried under vacuum to the anhydrous form. The purity was assessed by liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. The final concentration of each AZA in a CD(3)OH stock solution was determined by quantitative NMR spectroscopy. This solution was then diluted very accurately in degassed, high purity methanol to a concentration of 1.47 +/- 0.08 mu mol/L for CRM-AZA1, 1.52 +/- 0.05 mu mol/L for CRM-AZA2, and 1.37 +/- 0.13 mu mol/L for CRM-AZA3. Aliquots were dispensed into argon-filled glass ampoules, which were immediately flame-sealed. The calibration solutions are suitable for method development, method validation, calibration of liquid chromatography or mass spectrometry instrumentation and quality control of shellfish monitoring programs