A fumonisins immunosensor based on polyanilino-carbon nanotubes doped with palladium telluride quantum dots

An impedimetric immunosensor for fumonisins was developed based on poly(2,5-dimethoxyaniline)-multi-wall carbon nanotubes doped with palladium telluride quantum dots onto a glassy carbon surface. The composite was assembled by a layer-by-layer method to form a multilayer film of quantum dots (QDs) and poly(2,5-dimethoxyaniline)- multi-wall carbon nanotubes (PDMA-MWCNT). Preparation of the electrochemical immunosensor for fumonisins involved drop-coating of fumonisins antibody onto the composite modified glassy carbon electrode. The electrochemical impedance spectroscopy response of the FB1 immunosensor (GCE/PT-PDMA-MWCNT/anti-Fms-BSA) gave a linear range of 7 to 49 ng L−1 and the corresponding sensitivity and detection limits were 0.0162 kΩ L ng−1 and 0.46 pg L−1 , respectively, hence the limit of detection of the GCE/PT-PDMA-MWCNT immunosensor for fumonisins in corn certified material was calculated to be 0.014 and 0.011 ppm for FB1, and FB2 and FB3, respectively. These results are lower than those obtained by ELISA, a provisional maximum tolerable daily intake (PMTDI) for fumonisins (the sum of FB1, FB2, and FB3) established by the Joint FAO/WHO expert committee on food additives and contaminants of 2 μg kg−1 and the maximum level recommended by the U.S. Food and Drug Administration (FDA) for protection of human consumption (2–4 mg L−1 )

Ciliopathy is differentially distributed in the brain of a Bardet-Biedl syndrome mouse model

Bardet-Biedl syndrome (BBS) is a genetically heterogeneous inherited human disorder displaying a pleotropic phenotype. Many of the symptoms characterized in the human disease have been reproduced in animal models carrying deletions or knock-in mutations of genes causal for the disorder. Thinning of the cerebral cortex, enlargement of the lateral and third ventricles, and structural changes in cilia are among the pathologies documented in these animal models. Ciliopathy is of particular interest in light of recent studies that have implicated primary neuronal cilia (PNC) in neuronal signal transduction. In the present investigation, we tested the hypothesis that areas of the brain responsible for learning and memory formation would differentially exhibit PNC abnormalities in animals carrying a deletion of the Bbs4 gene (Bbs4-/-). Immunohistochemical localization of adenylyl cyclase-III (ACIII), a marker restricted to PNC, revealed dramatic alterations in PNC morphology and a statistically significant reduction in number of immunopositive cilia in the hippocampus and amygdala of Bbs4-/- mice compared to wild type (WT) littermates. Western blot analysis confirmed the decrease of ACIII levels in the hippocampus and amygdala of Bbs4-/- mice, and electron microscopy demonstrated pathological alterations of PNC in the hippocampus and amygdala. Importantly, no neuronal loss was found within the subregions of amygdala and hippocampus sampled in Bbs4-/- mice and there were no statistically significant alterations of ACIII immunopositive cilia in other areas of the brain not known to contribute to the BBS phenotype. Considered with data documenting a role of cilia in signal transduction these findings support the conclusion that alterations in cilia structure or neurochemical phenotypes may contribute to the cognitive deficits observed in the Bbs4-/- mouse mode. © 2014 Agassandian et al

Distinctive Left-Sided Distribution of Adrenergic-Derived Cells in the Adult Mouse Heart

Adrenaline and noradrenaline are produced within the heart from neuronal and non-neuronal sources. These adrenergic hormones have profound effects on cardiovascular development and function, yet relatively little information is available about the specific tissue distribution of adrenergic cells within the adult heart. The purpose of the present study was to define the anatomical localization of cells derived from an adrenergic lineage within the adult heart. To accomplish this, we performed genetic fate-mapping experiments where mice with the cre-recombinase (Cre) gene inserted into the phenylethanolamine-n-methyltransferase (Pnmt) locus were cross-mated with homozygous Rosa26 reporter (R26R) mice. Because Pnmt serves as a marker gene for adrenergic cells, offspring from these matings express the β-galactosidase (βGAL) reporter gene in cells of an adrenergic lineage. βGAL expression was found throughout the adult mouse heart, but was predominantly (89%) located in the left atrium (LA) and ventricle (LV) (p<0.001 compared to RA and RV), where many of these cells appeared to have cardiomyocyte-like morphological and structural characteristics. The staining pattern in the LA was diffuse, but the LV free wall displayed intermittent non-random staining that extended from the apex to the base of the heart, including heavy staining of the anterior papillary muscle along its perimeter. Three-dimensional computer-aided reconstruction of XGAL+ staining revealed distribution throughout the LA and LV, with specific finger-like projections apparent near the mid and apical regions of the LV free wall. These data indicate that adrenergic-derived cells display distinctive left-sided distribution patterns in the adult mouse heart

Adrenaline And Stress-Induced Cardiomyopathies: Three Competing Hypotheses For Mechanism(S) Of Action

Stress-induced cardiomyopathies such as Tako-Tsubo Syndrome (also known as Broken-Heart Syndrome ) primarily affect post-menopausal women who have experienced a sudden emotional shock. Clinical presentation includes symptoms mimicking a myocardial infarction (severe chest pain and S-T elevation on EKG), but do not show significant occlusion of the coronary arteries. Instead, patients display left ventricular (LV) dysfunction characterized by hypo- or a-kinetic regions that appear to balloon-out , particularly in the region near the apex, and thus is sometimes referred to as Apical-Ballooning Syndrome . Some patients have been reported with high circulating levels of adrenaline, and symptoms have been effectively managed in many cases by treatment with beta-adrenergic receptor blockers. It is not entirely clear, however, why only specific regions of the LV were affected in these patients, nor is it understood why postmenopausal women are so susceptible relative to the rest of the population. With respect to the first question, we will review three competing, though not necessarily mutually exclusive, hypotheses to explain how adrenaline plays a key role in precipitating stress-induced cardiomyopathies. The first of these is a vascular microspasm hypothesis which focuses on stress-induced changes in the coronary microvasculature feeding the LV, leading to microspasms, interrupted regional blood-flow, and corresponding myocardial dysfunction in affected areas of the LV (Sato et al., 1990 and Dote et al., J Cardiol 1991;21:203) [6, 7]. The second hypothesis will be referred to as the differential β-receptor expression hypothesis, which postulates there is a higher density of β-adrenergic, (especially β2-adrenergic) receptors in the apical region of the LV compared to other regions, thereby making it more sensitive to adrenergic overload and myocardial stunning due to agonist-mediated switch from Gs to Gi coupling of the β2-adrenergic receptors in this region relative to other regions of the heart (Lyon et al., Nature Clin Pract Cardiovasc Med 2008;5:22) [10]. A third hypothesis focuses on differential local production of adrenergic hormones within the left myocardium itself (Kume et al., Circ J 2008; 72:106 and Osuala et al., PLoS One 2011;8:e22811) [1, 3]. From this third hypothesis, selective myocardial stunning in the LV results from local overload of adrenergic stimulation due to autocrine/paracrine actions of adrenaline (epinephrine) and noradrenaline (norepinephrine) in addition to sympathetic stimulation and circulating catecholamines in periods of stress. The evidence for each hypothesis is critically evaluated, with discussion of potential future directions for work in this field in relation to the role of gender (sex), age, and menopausal status

Targeting Of The Enhanced Green Fluorescent Protein Reporter To Adrenergic Cells In Mice

Adrenaline and noradrenaline are important neurotransmitter hormones that mediate physiological stress responses in adult mammals, and are essential for cardiovascular function during a critical period of embryonic/fetal development. In this study, we describe a novel mouse model system for identifying and characterizing adrenergic cells. Specifically, we generated a reporter mouse strain in which a nuclear-localized enhanced green fluorescent protein gene (nEGFP) was inserted into exon 1 of the gene encoding Phenylethanolamine n-methyltransferase (Pnmt), the enzyme responsible for production of adrenaline from noradrenaline. Our analysis demonstrates that this knock-in mutation effectively marks adrenergic cells in embryonic and adult mice. We see expression of nEGFP in Pnmt-expressing cells of the adrenal medulla in adult animals. We also note that nEGFP expression recapitulates the restricted expression of Pnmt in the embryonic heart. Finally, we show that nEGFP and Pnmt expressions are each induced in parallel during the in vitro differentiation of pluripotent mouse embryonic stem cells into beating cardiomyocytes. Thus, this new mouse genetic model should be useful for the identification and functional characterization of adrenergic cells in vitro and in vivo. © 2012 Springer Science+Business Media, LLC

Impaired Cardiac Energy Metabolism In Embryos Lacking Adrenergic Stimulation

As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP to ATP in mitochondria becomes vital. Relatively little, however, is known about the signaling mechanisms regulating the transition from anaerobic to aerobic metabolism that occurs during the embryonic period. The main objective of this study was to test the hypothesis that adrenergic hormones provide critical stimulation of energy metabolism during embryonic/fetal development. We examined ATP and ADP concentrations in mouse embryos lacking adrenergic hormones due to targeted disruption of the essential dopamine β-hydroxylase (Dbh) gene. Embryonic ATP concentrations decreased dramatically, whereas ADP concentrations rose such that the ATP/ADP ratio in the adrenergicdeficient group was nearly 50-fold less than that found in littermate controls by embryonic day 11.5. We also found that cardiac extracellular acidification and oxygen consumption rates were significantly decreased, and mitochondria were significantly larger and more branched in adrenergic-deficient hearts. Notably, however, the mitochondria were intact with well-formed cristae, and there was no significant difference observed in mitochondrial membrane potential. Maternal administration of the adrenergic receptor agonists isoproterenol or L-phenylephrine significantly ameliorated the decreases in ATP observed in Dbh-/- embryos, suggesting that α- and β-adrenergic receptors were effective modulators of ATP concentrations in mouse embryos in vivo. These data demonstrate that adrenergic hormones stimulate cardiac energy metabolism during a critical period of embryonic development

Impaired cardiac energy metabolism in embryos lacking adrenergic stimulation

As development proceeds from the embryonic to fetal stages, cardiac energy demands increase substantially, and oxidative phosphorylation of ADP to ATP in mitochondria becomes vital. Relatively little, however, is known about the signaling mechanisms regulating the transition from anaerobic to aerobic metabolism that occurs during the embryonic period. The main objective of this study was to test the hypothesis that adrenergic hormones provide critical stimulation of energy metabolism during embryonic/fetal development. We examined ATP and ADP concentrations in mouse embryos lacking adrenergic hormones due to targeted disruption of the essential dopamine β-hydroxylase (Dbh) gene. Embryonic ATP concentrations decreased dramatically, whereas ADP concentrations rose such that the ATP/ADP ratio in the adrenergic-deficient group was nearly 50-fold less than that found in littermate controls by embryonic day 11.5. We also found that cardiac extracellular acidification and oxygen consumption rates were significantly decreased, and mitochondria were significantly larger and more branched in adrenergic-deficient hearts. Notably, however, the mitochondria were intact with well-formed cristae, and there was no significant difference observed in mitochondrial membrane potential. Maternal administration of the adrenergic receptor agonists isoproterenol or l-phenylephrine significantly ameliorated the decreases in ATP observed in Dbh(−/−) embryos, suggesting that α- and β-adrenergic receptors were effective modulators of ATP concentrations in mouse embryos in vivo. These data demonstrate that adrenergic hormones stimulate cardiac energy metabolism during a critical period of embryonic development

Intracardiac intracellular angiotensin system in diabetes.

Item does not contain fulltextThe renin-angiotensin system (RAS) has mainly been categorized as a circulating and a local tissue RAS. A new component of the local system, known as the intracellular RAS, has recently been described. The intracellular RAS is defined as synthesis and action of ANG II intracellularly. This RAS appears to differ from the circulating and the local RAS, in terms of components and the mechanism of action. These differences may alter treatment strategies that target the RAS in several pathological conditions. Recent work from our laboratory has demonstrated significant upregulation of the cardiac, intracellular RAS in diabetes, which is associated with cardiac dysfunction. Here, we have reviewed evidence supporting an intracellular RAS in different cell types, ANG II's actions in cardiac cells, and its mechanism of action, focusing on the intracellular cardiac RAS in diabetes. We have discussed the significance of an intracellular RAS in cardiac pathophysiology and implications for potential therapies

Electrochemical Aptatoxisensor Responses on Nanocomposites Containing Electro-Deposited Silver Nanoparticles on Poly(Propyleneimine) Dendrimer for the Detection of Microcystin-LR in Freshwater

A sensitive and reagentless electrochemical aptatoxisensor was developed on cobalt (II) salicylaldiimine metallodendrimer (SDD–Co(II)) doped with electro-synthesized silver nanoparticles (AgNPs) for microcystin-LR (L, l-leucine; R, l-arginine), or MC-LR, detection in the nanomolar range. The GCE|SDD–Co(II)|AgNPs aptatoxisensor was fabricated with 5’ thiolated aptamer through self-assembly on the modified surface of the glassy carbon electrode (GCE) and the electronic response was measured using cyclic voltammetry (CV). Specific binding of MC-LR with the aptamer on GCE|SDD–Co(II)|AgNPs aptatoxisensor caused the formation of a complex that resulted in steric hindrance and electrostatic repulsion culminating in variation of the corresponding peak current of the electrochemical probe. The aptatoxisensor showed a linear response for MC-LR between 0.1 and 1.1 µg·L−1 and the calculated limit of detection (LOD) was 0.04 µg·L−1. In the detection of MC-LR in water samples, the aptatoxisensor proved to be highly sensitive and stable, performed well in the presence of interfering analog and was comparable to the conventional analytical techniques. The results demonstrate that the constructed MC-LR aptatoxisensor is a suitable device for routine quantification of MC-LR in freshwater and environmental samples