Morphological and Pathological Evolution of the Brain Microcirculation in Aging and Alzheimer’s Disease

Key pathological hallmarks of Alzheimer’s disease (AD), including amyloid plaques, cerebral amyloid angiopathy (CAA) and neurofibrillary tangles do not completely account for cognitive impairment, therefore other factors such as cardiovascular and cerebrovascular pathologies, may contribute to AD. In order to elucidate the microvascular changes that contribute to aging and disease, direct neuropathological staining and immunohistochemistry, were used to quantify the structural integrity of the microvasculature and its innervation in three oldest-old cohorts: 1) nonagenarians with AD and a high amyloid plaque load; 2) nonagenarians with no dementia and a high amyloid plaque load; 3) nonagenarians without dementia or amyloid plaques. In addition, a non-demented (ND) group (average age 71 years) with no amyloid plaques was included for comparison. While gray matter thickness and overall brain mass were reduced in AD compared to ND control groups, overall capillary density was not different. However, degenerated string capillaries were elevated in AD, potentially suggesting greater microvascular “dysfunction” compared to ND groups. Intriguingly, apolipoprotein ε4 carriers had significantly higher string vessel counts relative to non-ε4 carriers. Taken together, these data suggest a concomitant loss of functional capillaries and brain volume in AD subjects. We also demonstrated a trend of decreasing vesicular acetylcholine transporter staining, a marker of cortical cholinergic afferents that contribute to arteriolar vasoregulation, in AD compared to ND control groups, suggesting impaired control of vasodilation in AD subjects. In addition, tyrosine hydroxylase, a marker of noradrenergic vascular innervation, was reduced which may also contribute to a loss of control of vasoconstriction. The data highlight the importance of the brain microcirculation in the pathogenesis and evolution of AD

Vascular Kv7 channels control intracellular Ca2+ dynamics in smooth muscle

Voltage-gated Kv7 (or KCNQ) channels control activity of excitable cells, including vascular smooth muscle cells (VSMCs), by setting their resting membrane potential and controlling other excitability parameters. Excitation-contraction coupling in muscle cells is mediated by Ca2+ but until now, the exact role of Kv7 channels in cytosolic Ca2+ dynamics in VSMCs have not been fully elucidated. We utilised microfluorimetry to investigate the impact of Kv7 channel activity on intracellular Ca2+ levels and electrical activity of rat A7r5 VSMCs and primary human internal mammary artery (IMA) SMCs. Both, direct (XE991) and G protein coupled receptor mediated (vasopressin, AVP) Kv7 channel inhibition induced robust Ca2+ oscillations, which were significantly reduced in the presence of Kv7 channel activator, retigabine, L-type Ca2+ channel inhibitor, nifedipine, or T-type Ca2+ channel inhibitor, NNC 55-0396, in A7r5 cells. Membrane potential measured using FluoVolt exhibited a slow depolarisation followed by a burst of sharp spikes in response to XE991; spikes were temporally correlated with Ca2+ oscillations. Phospholipase C inhibitor (edelfosine) reduced AVP-induced, but not XE991-induced Ca2+ oscillations. AVP and XE991 induced a large increase of [Ca2+]i in human IMA, which was also attenuated with retigabine, nifedipine and NNC 55-0396. RT-PCR, immunohistochemistry and electrophysiology suggested that Kv7.5 was the predominant Kv7 subunit in both rat and human arterial SMCs; CACNA1C (Cav1.2; L-type) and CACNA1 G (Cav3.1; T-type) were the most abundant voltage-gated Ca2+ channel gene transcripts in both types of VSMCs. This study establishes Kv7 channels as key regulators of Ca2+ signalling in VSMCs with Kv7.5 playing a dominant role

Regulating cellular trace metal economy in algae.

As indispensable protein cofactors, Fe, Mn, Cu and Zn are at the center of multifaceted acclimation mechanisms that have evolved to ensure extracellular supply meets intracellular demand. Starting with selective transport at the plasma membrane and ending in protein metalation, metal homeostasis in algae involves regulated trafficking of metal ions across membranes, intracellular compartmentalization by proteins and organelles, and metal-sparing/recycling mechanisms to optimize metal-use efficiency. Overlaid on these processes are additional circuits that respond to the metabolic state as well as to the prior metal status of the cell. In this review, we focus on recent progress made toward understanding the pathways by which the single-celled, green alga Chlamydomonas reinhardtii controls its cellular trace metal economy. We also compare these mechanisms to characterized and putative processes in other algal lineages. Photosynthetic microbes continue to provide insight into cellular regulation and handling of Cu, Fe, Zn and Mn as a function of the nutritional supply and cellular demand for metal cofactors. New experimental tools such as RNA-Seq and subcellular metal imaging are bringing us closer to a molecular understanding of acclimation to supply dynamics in algae and beyond

Macrophages behavior on different NIPAm-based thermoresponsive substrates

Thermoresponsive materials and surfaces are widely used in cell culture applications. There is a lot of research work employing thermoresponsive materials with various structure and compositions. However, little is known about the immunological response to the thermoresponsive materials. Macrophage-like transformed murine cell line RAW264.7 was selected as it is a widely used standard model for immune activation analysis. This study proposes to compare the effects of thermoresponsive films with various compositions on macrophage cells. Thermoresponsive materials are a useful utility as a non-enzymatic harvesting system for tissue culture. As RAW264.7 cells are difficult to remove from the substrate by enzymatic methods we also explored the possibility to use thermoresponsive materials for the macrophage cultivation. Spin coating and solvent casting was used to produce films of N-isopropylacrylamide-based polymers from the nanometer to micrometer range. Successful cell adhesion and proliferation was highly dependent on the thickness and composition of the coating. RAW264.7 cells were successfully detached from the coatings upon temperature reduction. Furthermore, results indicate that the RAW264.7 cells remained inactivated as cell secreted cytokine remained at a low level and the surface receptor profile of RAW264.7 was not altered when cells were detached in this manner.Peer Reviewe

Quality assessment of industrial prefried french fries

33 ref.International audienc

Magnesium Deficiency Causes Loss of Response to Intermittent Hypoxia in Paraganglion Cells*

Magnesium deficiency is suggested to contribute to many age-related diseases. Hypoxia-inducible factor 1α (HIF-1α) is known to be a master regulator of hypoxic response. Here we show that hypomagnesemia suppresses reactive oxygen species (ROS)-induced HIF-1α activity in paraganglion cells of the adrenal medulla and carotid body. In PC12 cells cultured in the low magnesium medium and treated with cobalt chloride (CoCl2) or exposed to intermittent hypoxia, ROS-mediated HIF-1α activity was suppressed. This suppression was due to up-regulation of inhibitory PAS (Per/Arnt/Sim) domain protein (IPAS) that was caused by NF-κB activation, which resulted from ROS and calcium influx mainly through the T-type calcium channels. Induction of tyrosine hydroxylase, a target of HIF-1, by CoCl2 injection was suppressed in the adrenal medulla of magnesium-deficient mice because of up-regulation of IPAS. Also in the carotid body of magnesium-deficient mice, CoCl2 and chronic intermittent hypoxia failed to enhance the tyrosine hydroxylase expression. These results demonstrate that serum magnesium levels are a key determinant for ROS-induced hypoxic responses