When, where and how? Focus on neuronal calcium dysfunctions in Alzheimer's Disease.

Alzheimer\u2019s disease (AD), since its characterization as a precise form of dementia with its own pathological hallmarks, has captured scientists\u2019 attention because of its complexity. The last 30 years have been filled with discoveries regarding the elusive aetiology of this disease and, thanks to advances in molecular biology and live imaging techniques, we now know that an important role is played by calcium (Ca2+). Ca2+, as ubiquitous second messenger, regulates a vast variety of cellular processes, from neuronal excitation and communication, to muscle fibre contraction and hormone secretion, with its action spanning a temporal scale that goes from microseconds to hours. It is therefore very challenging to conceive a single hypothesis that can integrate the numerous findings on this issue with those coming from the classical fields of AD research such as amyloid-beta (A) and tau pathology. In this contribution, we will focus our attention on the Ca2+ hypothesis of AD, dissecting it, as much as possible, in its subcellular localization, where the Ca2+ signal meets its specificity. We will also follow the temporal evolution of the Ca2+ hypothesis, providing some of the most updated discoveries. Whenever possible, we will link the findings regarding Ca2+ dysfunction to the other players involved in AD pathogenesis, hoping to provide a crossover body of evidence, useful to amplify the knowledge that will lead towards the discovery of an effective therapy

Temperature dependence of the surface plasmon resonance in small electron gas fragments, self consistent field approximation

The temperature dependence of the surface plasmon resonance in small metal spheres is calculated using an electron gas model within the Random Phase Approximation. The calculation is mainly devoted to the study of spheres with diameters up to at least 10 nm, where quantum effects can still be relevant and simple plasmon pole approximation for the dielectric function is no more appropriate. We find a possible blue shift of the plasmon resonance position when the temperature is increased while keeping the size of the sphere fixed. The blue shift is appreciable only when the temperature is a large fraction of the Fermi energy. These results provide a guide for pump and probe experiments with a high time resolution, and tailored to study the excited electron system before thermalisation with the lattice takes place.Comment: 5 pages, 3 figure

Assessing the occurrence and transfer dynamics of ESBL/pAmpC-producing Escherichia coli across the broiler production pyramid

Extended-spectrum \u3b2-lactamase (ESBL)- and plasmid mediated AmpC-type cephalosporinase (pAmpC)-producing Escherichia coli (ESBL/pAmpC E. coli) in food-producing animals is a major public health concern. This study aimed at quantifying ESBL/pAmpC-E. coli occurrence and transfer in Italy's broiler production pyramid. Three production chains of an integrated broiler company were investigated. Cloacal swabs were taken from parent stock chickens and offspring broiler flocks in four fattening farms per chain. Carcasses from sampled broiler flocks were collected at slaughterhouse. Samples were processed on selective media, and E. coli colonies were screened for ESBL/pAmpC production. ESBL/pAmpC genes and E. coli phylogroups were determined by PCR and sequencing. Average pairwise overlap of ESBL/pAmpC E. coli gene and phylogroup occurrences between subsequent production stages was estimated using the proportional similarity index, modelling uncertainty in a Monte Carlo simulation setting. In total, 820 samples were processed, from which 513 ESBL/pAmpC E. coli isolates were obtained. We found a high prevalence (92.5%, 95%CI 72.1-98.3%) in day-old parent stock chicks, in which blaCMY-2 predominated; prevalence then dropped to 20% (12.9-29.6%) at laying phase. In fattening broilers, prevalence was 69.2% (53.6-81.3%) at the start of production, 54.2% (38.9-68.6%) at slaughter time, and 61.3% (48.1-72.9%) in carcasses. Significantly decreasing and increasing trends for respectively blaCMY-2 and blaCTX-M-1 gene occurrences were found across subsequent production stages. ESBL/pAmpC E. coli genetic background appeared complex and bla-gene/phylogroup associations indicated clonal and horizontal transmission. Modelling revealed that the average transfer of ESBL/pAmpC E. coli genes between subsequent production stages was 47.7% (42.3-53.4%). We concluded that ESBL/pAmpC E. coli in the broiler production pyramid is prevalent, with substantial transfer between subsequent production levels

Effect of membrane potential on divalent cation transport catalyzed by the "electroneutral" ionophores A23187 and ionomycin.

Depolarization of plasma membrane potential has a potent inhibitory effect on divalent cation influx catalyzed by the carboxylic ionophores ionomycin and A23187. This effect is observed in different cell models and does not depend on either inhibition of Ca2+-activated cation channels or activation of Ca2+ extrusion mechanisms as suggested previously. A dependence of divalent cation influx on the magnitude of membrane potential is observed also in artificial liposomes. The inhibition of ionophore-dependent divalent cation transport by membrane potential depolarization can be modified varying the ionophore concentration and the external pH. These findings suggest that both neutral and positively charged ionophore-cation complexes can cross the plasma membrane and that their contribution to the overall transport process can be varied according to the experimental conditions

Intracellular ADP modulates the Ca2+ release-activated Ca2+ current in a temperature- and Ca2+-dependent Way.

Abstract The rat basophilic cell line RBL-1 is known to express high levels of the Ca current activated by store depletion, known as Ca release-activated Ca current (I), the main Ca influx pathway so far identified in nonexcitable cells. We show here that, as reported in other cell types, metabolic drugs strongly inhibit the Ca influx operated by store depletion in RBL-1 cells also. We have tested the hypothesis that intracellular adenine and/or guanine nucleotide levels act as coupling factors between I and cell metabolism. Using the whole cell configuration of the patch-clamp technique, we demonstrate that addition of ADP to the intracellular solution significantly reduces I induced by inositol 1,4,5-trisphosphate. This phenomenon differs from other regulatory pathways of I, since it is highly temperature-dependent, is observable only in the presence of low intracellular Ca buffering capacity, and requires a cytosolic factor(s) which is rapidly lost during cell dialysis. Moreover, the inhibition is specific for ADP and is partially mimicked by ADPβS and AMP, but not by GDP or GTP

Contribution of natural milk culture to microbiota, safety and hygiene of raw milk cheese produced in alpine malga

Processing of alpine milk in malga farms is carried out under conditions that can favor contamination by coliforms, coagulase-positive staphylococci, or pathogens such as Listeria monocytogenes. With the aim to improve the hygienic characteristics and safety of cheese produced in four malga farms the use of lyophilized Natural Milk Culture prepared with selected strains was tested.. Two cheesemaking tests were carried out in the same day always starting from the same milk: in the first case following the malga recipe that uses either Natural Whey Culture or without the addition of a starter, in the second one using a Natural Milk Culture. Cheesemaking were carried out in four malga farms located in the west area of Trentino region within the same week. For hygienic and safety evaluation, aerobic colony count, coagulase-positive staphylococci, Escherichia coli, staphylococcal toxins, Listeria monocytogenes, and Salmonella spp, pH and aw were determined in raw milk from evening and morning milking, curd in vat, curd after extraction and two months-ripened cheese. Pathogens or toxins, high values of coagulase- positive staphylococci and E. coli were not found in cheese samples. However, in the curd coagulase-positive staphylococci reached values almost of 5 Log CFU/g in the two malga without starter cultures. The use of Natural Milk Culture reduced E. coli counts. In addition, DNA was extracted from cheese samples and from Natural Milk Culture and the composition of the microbial community determined by Next Generation Sequencing method. The determination of cheese microbial communities demonstrated that the use of Natural Milk Culture exerted different effects in the different malga, in any case preserving bacterial biodiversity

Effect of the partial replacement of fish meal and oil by vegetable products on performance and quality traits of juvenile shi drum (Umbrina cirrosa L.)

A four-month growth trial was carried out in order to evaluate performance and quality traits of juvenile shi drum fedwith two isonitrogenous and isoenergetic diets having different amounts of vegetable products (Vegetable diet vs. Controldiet). Compared to the Control diet, the Vegetable diet was formulated by increasing the replacement of fish meal (14%)with soybean and cereal products, and fish oil (12%) with a mixture of vegetable oil. On June, 4 groups of 225 fish (2replicates per dietary treatment) were sorted according to live weight and reared in fibreglass tanks over a four- monthlong experimental period. Fish were hand fed to apparent satiety. Offered feed, growth parameters and feed efficiencywere recorded as productive performance. At the end of the trial (October) biometric, chemical and reological traits wereexamined to assess fish quality. The dietary treatments showed similar productive performance. The relatively high inclusionof vegetable sources led to a significant modification of body shape, mesenteric fat and viscera weight. Among qualitytraits, Vegetable diet-fed fish demonstrated a significantly lower whole body and fillet crude protein content.Yellowness value of the cooked fillet was significantly lower in the Control diet-fed fish, whereas fillet texture was similar.The results of this research showed that shi drum is a suitable candidate for Mediterranean marine aquaculture andits dietary formulation might include at least the amount of vegetable sources used in this trial

Generation of inositol phosphates, cytosolic Ca2+, and ionic fluxes in PC12 cells treated with bradykinin

Abstract Accumulation of inositol phosphates (Ins-Ps, revealed by high performance liquid chromatography), changes of the cytosolic free Ca2+ [( Ca2+]i, revealed by fura-2), membrane potential and ionic currents (revealed by bis-oxonol and patch clamping) were investigated in PC12 cells treated with bradykinin (BK). The phenomena observed were (a) due to the activation of a B2 receptor (inhibitor studies) and (b) unaffected by pertussis toxin, cAMP analogs, and inhibitors of either cyclooxygenase or voltage-gated Ca2+ channels. During the initial tens of s, three interconnected events predominated: accumulation of Ins-1,4,5-P3, Ca2+ release from intracellular stores and hyperpolarization due to the opening of Ca2+-activated K+ channels. Phorbol myristate acetate partially inhibited Ins-1,4,5-P3 accumulation at all [BK] investigated, and the [Ca2+]i increase at [BK] less than 50 nM. In PC12 cells treated with maximal [BK] in the Ca2+-containing incubation medium, Ins-1,4,5-P3 peaked at 10 s, dropped to 20% of the peak at 30 s, and returned to basal within 5 min; the peak increase of Ins-1,3,4-P3 was slower and was variable from experiment to experiment, while Ins-P4 rose for 2 min, and remained elevated for many min thereafter. Meanwhile, influx of Ca2+ from the extracellular medium, plasma membrane depolarization (visible without delay when hyperpolarization was blocked), and increased plasma membrane conductance were noticed. Evidence is presented that these last three events (which were partially inhibited by phorbol myristate acetate at all [BK]) were due to the activation of a cation influx, which was much more persistent than the elevation of the two Ins-P3 isomers. Our results appear inconsistent with the possibility that in intact PC12 cells the BK-induced activation of cation influx is accounted for entirely by the increases of either Ins-1,3,4-P3 or Ins-1,4,5-P3 (alone or in combination with Ins-1,3,4,5-P4), as previously suggested by microinjection studies in different cell types