Cathodic disbonding tests operating at large cathodic potentials for long periods need current monitoring, pH control and anode isolation

Metallic structures in service in seawater are protected coupling cathodic protection and paints, where the former may induce disbondment of the latter. A preliminary evaluation of the cathodic disbondment risk can be made by cathodic disbondment tests, CDTs. Many CDTs use cathodic potentials as large as E < -1400 mV vs SCE applied up to 90 days. Only two CDT protocols require contemporary anode isolation, current and pH monitoring, without its correction. These three aspects were considered to develop a hybrid CDT; it consisted in polarizing steel panels at -1500 mV vs SCE for 12 weeks. The chemical effects related to the anodic processes were investigated. The observed pH acidic shift was justified by the increasing current demand due to paint damage and brucite precipitation on the panels. The necessity of anode isolating glass to prevent chlorine related chemical attack over the paints, potentially affecting the disbondment result, was verified. In conclusion, current monitoring, pH control and anode isolation are highly suggested to correctly interpret the cathodic disbondment results when CDTs requiring large electronegative potentials are applied for long periods

Calpain digestion and HSP90-based chaperone protection modulate the level of plasma membrane F508del-CFTR

AbstractWe are here showing that peripheral mononuclear blood cells (PBMC) from cystic fibrosis (CF) patients contain almost undetectable amounts of mature 170 kDa CF-transmembrane conductance regulator (CFTR) and a highly represented 100 kDa form. This CFTR protein, resembling the form produced by calpain digestion and present, although in lower amounts, also in normal PBMC, is localized in cytoplasmic internal vesicles. These observations are thus revealing that the calpain-mediated proteolysis is largely increased in cells from CF patients. To characterize the process leading to the accumulation of such split CFTR, FRT cells expressing the F508del-CFTR mutated channel protein and human leukaemic T cell line (JA3), expressing wild type CFTR were used. In in vitro experiments, the sensitivity of the mutated channel to the protease is identical to that of the wild type, whereas in Ca2+-loaded cells F508del-CFTR is more susceptible to digestion. Inhibition of intracellular calpain activity prevents CFTR degradation and leads to a 10-fold increase in the level of F508del-CFTR at the plasma membrane, further indicating the involvement of calpain activity in the maintenance of very low levels of mature channel form. The higher sensitivity to calpain of the mutated 170 kDa CFTR results from a reduced affinity for HSP90 causing a lower degree of protection from calpain digestion. The recovery of HSP90 binding capacity in F508del-CFTR, following digestion, explains the large accumulation of the 100 kDa CFTR form in circulating PBMC from CF patients

Biochimica

Questa settima edizione di Biochimica rende conto dei pi\uf9 recenti progressi attraverso un linguaggio chiaro e accessibile anche per quegli studenti che si avvicinano per la prima volta allo studio della disciplina. Le caratteristiche che, fin dalla prima edizione, rendono la Biochimica di Stryer uno dei libri di testo pi\uf9 diffusi sono: l\u2019organizzazione del testo semplice e logica: guida il lettore attraverso i processi e lo aiuta a districarsi nella complessit\ue0 dei meccanismi e delle vie metaboliche; le illustrazioni dedicate a singoli concetti: ogni immagine riesce a descrivere e spiegare un meccanismo oppure a raccontare tutto ci\uf2 che accade in una determinata via metabolica o in un dato processo biochimico senza distrarre l\u2019attenzione con un eccesso di dettagli; la rilevanza fisiologica: il testo aiuta lo studente a collegare la biochimica alla propria vita; le vie metaboliche e i processi sono presentati sempre nel loro contesto fisiologico, in modo che si possa apprezzare come la biochimica lavori nei diversi distretti dell\u2019organismo e in diverse condizioni, sia ambientali sia di stimolazione ormonale; gli approfondimenti clinici: ovunque fosse appropriato, le vie metaboliche e/o i meccanismi sono stati applicati alla fisiologia e alla patologia; le prospettive evoluzionistiche: l\u2019evoluzione \ue8 evidente sia nelle strutture sia nelle vie metaboliche biochimiche ed \ue8 puntualmente evidenziata

Attrazione Fatale - Metalli e ambiente: le trasformazioni dei materiali tra patina nobile e prodotti di corrosione

Would you like to get into the forge of the gods like Hephaestus? Discover how to extract the metals and get objects of fine workmanship? But beware: there is rust on the prowl! We go behind the scenes to explore the adventure of mankind in the art of producing lovely jewelry, melt the bells and monuments, getting mixed metal alloys of different colours. Let\u27s explore the irresistible attraction of metals and alloys with the environment: are you ready for a fast journey through transformations? What are the substances that ruin the features? How can we combat the degradation? With this practical workshop we want honour Giulio Natta in the fifty years anniversary of his Nobel Prize for Chemistry.Ti piacerebbe mettere piede nella fucina degli dei come Efesto? Scoprire come estrarre i metalli e ottenere oggetti di finissima fattura? Ma attenzione: c\u27? la ruggine in agguato! Andiamo dietro le quinte per esplorare l\u27avventura del genere umano nell\u27arte di produrre graziosi monili, fondere campane e monumenti, miscelare metalli ottenendo leghe di diversi colori. Esploriamo l\u27attrazione pi? o meno irresistibile di metalli e leghe con l\u27ambiente: sei pronto a un viaggio accelerato nelle trasformazioni? Quali sono le sostanze che ne rovinano le caratteristiche? Come possiamo combattere il degrado? Un laboratorio pratico per ricordare Giulio Natta a cinquanta anni dal suo Nobel per la chimica

Evidence for alteration of calpain/calpastatin system in PBMC of cystic fibrosis patients

We are here reporting that in peripheral blood mononuclear cells (PBMC) of patients homozygous for F508del-CFTR the calpain\u2013calpastatin system undergoes a profound alteration. In fact, calpain basal activity, almost undetectable in control PBMC, becomes measurable at a significant extent in cells from cystic fibrosis (CF) patients, also due to a 40\u201360% decrease in both calpastatin protein and inhibitory activity. Constitutive protease activation in CF patients' cells induces a large accumulation of the mutated cystic fibrosis transmembrane conductance regulator (CFTR) in the 100 kD + 70 kD split forms as well as a degradation of proteins associated to the CFTR complex. Specifically, the scaffolding protein Na+/H+ exchanger 3 regulatory factor-1 (NHERF-1) is converted in two distinct fragments showing masses of 35 kD and 20 kD, being however the latter form the most represented one, thereby indicating that in CF-PBMC the CFTR complex undergoes a large disorganization. In conclusion, our observations are providing new information on the role of calpain in the regulation of plasma membrane ion conductance and provide additional evidence on the transition of this protease activity from a physiological to a pathological function. \ua9 2011 Elsevier B.V. All rights reserve

Necrosis of the nipple-areola complex in breast reduction: our personal way to solve problem

Necrosis of the NAC is a condition that penalizes patients who underwent breast reduction surgery or mastopexy. Breast reduction is a widely used technique for over-sized breasts. Breast hypertrophy, in fact, can cause the onset of many issues - both aesthetical and pathological - because of the excessive weight that the breasts exert on the patient\u2019s spine. Aim and objective of our study is to suggest a systematic use of diagnostic imaging composed of pre-operative and intraoperative ultrasound with color-Doppler and pre-operative MRI. Trying to solve this problem definitively, we relied on our notions of anatomy on ten fresh cadavers, on whose twenty breasts we could make very detailed dissections. The dissections led us to conclude that, albeit with their anatomic differences, each breast was characterized by a vascular-nervous pedicle coming out from the inter-costal spaces and aimed to the blood supply to the NAC. To overcome the anatomic variations between one subject and another - but also between one breast and the other from the same patient, we relied on diagnostic imaging, both in the pre-operative and in the intra-operative staging. This way we were able to intervene successfully with 15 patients, none of which has complained damages to the vascularity or innervation of the NAC so far. In conclusion we believe that pre and intra operative diagnostic imaging is the only way to completely eliminate any potential risk of NAC necrosis. Only by means of the systematic use of conventional imaging - especially during surgery - it is possible to constantly monitor the position of the NAC\u2019s pedicle in a breast that is being reduced in volume

Characterization of a new p94-like calpain form in human lymphocytes.

Human circulating PBMC (peripheral blood mononuclear cells) contain three calpain isoforms distinguishable on the basis of their chromatographic properties. Two of these proteases belong to the ubiquitous calpain subfamily, corresponding to the classical mu- and m-calpain forms. The third, which shows peculiar activating and regulatory properties, is an alternatively spliced calpain 3 (p94) form. This new calpain differs from calpain 3 in that it has lost IS1 insertion and exon 15, a lysine-rich sequence regarded as a nuclear translocation signal. PBMC p94-calpain undergoes activation and inactivation without the accumulation of a low-Ca2+-requiring form that is typical of the classical activation processes of mu- and m-calpain. Furthermore, it differs from the ubiquitous forms in that it displays a lower sensitivity to calpastatin. On the basis of these selective properties, it can be postulated that PBMC p94-calpain can be activated in response to specific stimuli that are not effective on the other calpain isoenzymes. The enzyme is preferentially expressed in B- and T-lymphocytes, whereas it is poorly expressed in natural killer cells and almost undetectable in polymorphonuclear cells. This distribution might reflect the specific function of this protease, which is preferentially present in cells devoted to the production of the humoral, rather than to the cellular, immune response

Calpain-1 resident in lipid raft/caveolin-1 membrane microdomains plays a protective role in endothelial cells.

We are here reporting that calpain-1 is a constitutive component of a distinct lipid raft/caveolin-1 microdomain isolated from bEnd5 cells in association with endothelial nitric oxide synthase (eNOS) and heat shock protein 90 (HSP90). Perturbations in intracellular calcium concentration by Ca2+-ionophore A23187 or prolonged cell exposure to high glucose induce a significant decrease in the level of eNOS accompanied by a recruitment of additional HSP90 molecules at this site. In these conditions the cells are more resistant to cell death by Ca2+ overload. The decrease of eNOS has been due not only to its Ca2+-mediated release from the caveolin-1 aggregates but also to its digestion by calpain-1. The specific involvement of calpain-1 in digestion of eNOS is supported by the preventive effect of a synthetic calpain inhibitor (CI-2) and by the absence of calpain-2 and calpastatin in the caveolin-1 microdomain. These results suggest that the protein adjustments observed in lipid raft/caveolin-1 microdomains could be visualized as a process required to protect the cells against NO overproduction and aberrant calpain activation. Alterations in eNOS, calpain-1 and HSP90 levels have been observed in aorta of Zucker Diabetic Rats (ZDR). The loss of HSP90 occurring in these animals indicates an aberrant activation of calpain and thereby the transition from a physiological to a pathological cell condition