Search results for " Aggregation"
showing 10 items of 441 documents
Neutron Scattering Reveals Enhanced Protein Dynamics in Concanavalin A Amyloid Fibrils
2012
Protein aggregation is one of the most challenging topics in life sciences, and it is implicated in several human pathologies. The nature and the role of toxic species is highly debated, with amyloid fibrils being among the most relevant species for their peculiar structural and functional properties. Protein dynamics and in particular the ability to fluctuate through a large number of conformational substates are closely related to protein function. This Letter focuses on amyloid fibril dynamics, and, to our knowledge, it is the first neutron scattering study on a protein (Concanavalin A) isolated in its fibril state. Our results reveal enhanced atomic fluctuations in amyloid fibrils and i…
Purification and partial characterization of a lectin protein complex, the clathrilectin, from the calcareous sponge Clathrina clathrus
2016
Carbohydrate-binding proteins were purified from the marine calcareous sponge Clathrina clathrus via affinity chromatography on lactose and N-acetyl glucosamine- agarose resins. Proteomic analysis of acrylamide gel separated protein subunits obtained in reducing conditions pointed out several candidates for lectins. Based on amino- acid sequence similarity, two peptides displayed homology with the jack bean lectin Concanavalin A, including a conserved domain shared by proteins in the L-type lectin superfamily. An N-acetyl glucosamine - binding protein complex, named clathrilectin, was further purified via gel filtration chromatography, bioguided with a diagnostic rabbit erythrocyte haemag…
Human apolipoprotein A-I natural variants: molecular mechanisms underlying amyloidogenic propensity
2012
Human apolipoprotein A-I (apoA-I)-derived amyloidosis can present with either wild-type (Wt) protein deposits in atherosclerotic plaques or as a hereditary form in which apoA-I variants deposit causing multiple organ failure. More than 15 single amino acid replacement amyloidogenic apoA-I variants have been described, but the molecular mechanisms involved in amyloid-associated pathology remain largely unknown. Here, we have investigated by fluorescence and biochemical approaches the stabilities and propensities to aggregate of two disease-associated apoA-I variants, apoA-IGly26Arg, associated with polyneuropathy and kidney dysfunction, and apoA-ILys107-0, implicated in amyloidosis in severe…
Actinopathies and Myosinopathies
2009
The currently recognized two forms of "anabolic" protein aggregate myopathies, that is, defects in development, maturation and final formation of respective actin and myosin filaments encompass actinopathies and myosinopathies. The former are marked by mutations in the ACTA1 gene, largely of the de novo type. Aggregates of actin filaments are deposited within muscle fibers. Early clinical onset is often congenital; most patients run a rapidly progressive course and die during their first 2 years of life. Myosinopathies or myosin storage myopathies also commence in childhood, but show a much more protracted course owing to mutations in the myosin heavy chain gene MYH7. Protein aggregation co…
Kinetic evidence for the solubilization of pyridine-2-azo-p-dimethylaniline in alkanediyl-α,ω-bis(dimethylcetylammonium nitrate) surfactants. Role of…
2004
The incorporation of the bidentate ligand pyridine-2-azo-p-dimethylaniline (PADA) into micellar aggregates of the dimeric cationic surfactants propanediyl-, hexanediyl- and dodecanediyl-alpha,omega-bis(dimethylcetylammonium nitrate) (16-3-16,2NO(3)(-), 16-6-16,2NO(3)(-) and 16-12-16,2NO(3)(-), respectively) has been studied at 25 degreesC by examining the kinetics of the complexation reaction of the Ni(II) ion with this ligand. For comparison, cetyltrimethylammonium nitrate ( CTAN), which can be considered as the "monomeric'' surfactant of 16-3-16,2NO(3)(-), has also been used. The kinetic data have shown that, for 16-3-16,2NO(3)(-) and CTAN, at a surfactant concentration below the critical…
Joint use of cardio-embolic and bleeding risk scores in elderly patients with atrial fibrillation
2013
Background Scores for cardio-embolic and bleeding risk in patients with atrial fibrillation are described in the literature. However, it is not clear how they co-classify elderly patients with multimorbidity, nor whether and how they affect the physician's decision on thromboprophylaxis. Methods Four scores for cardio-embolic and bleeding risks were retrospectively calculated for ⥠65 year old patients with atrial fibrillation enrolled in the REPOSI registry. The co-classification of patients according to risk categories based on different score combinations was described and the relationship between risk categories tested. The association between the antithrombotic therapy received and t…
Mortality rate and risk factors for gastrointestinal bleeding in elderly patients
2019
Abstract Background Gastrointestinal bleeding (GIB) is burdened by high mortality rate that increases with aging. Elderly patients may be exposed to multiple risk factors for GIB. We aimed at defining the impact of GIB in elderly patients. Methods Since 2008, samples of elderly patients (age ≥ 65 years) with multimorbidity admitted to 101 internal medicine wards across Italy have been prospectively enrolled and followed-up (REPOSI registry). Diagnoses of GIB, length of stay (LOS), mortality rate, and possible risk factors, including drugs, index of comorbidity (Cumulative Illness Rating Scale [CIRS]), polypharmacy, and chronic diseases were assessed. Adjusted multivariate logistic regressio…
The putative sponge aggregation receptor. Isolation and characterization of a molecule composed of scavenger receptor cysteine-rich domains and short…
1998
Porifera (sponges) are the oldest extant metazoan phylum. Dissociated sponge cells serve as a classic system to study processes of cell reaggregation. The reaggregation of dissociated cells is mediated by an extracellularly localized aggregation factor (AF), based on heterophilic interactions of the third order; the AF bridges two cells by ligating a cell-surface-bound aggregation receptor (AR). In the present study we report cloning, expression and immunohistochemical localization of a polypeptide from the marine sponge Geodia cydonium, which very likely represents the AR. The presumed AR gene gives rise to at least three forms of alternatively spliced transcripts of 6.5, 4.9 and 3.9 kb, a…
Nest aggregation and reproductive synchrony promote Lesser Kestrel Falco naumanni seasonal fitness
2013
Several factors promote coloniality by enhancing the fitness of colony members. In birds, spatial proximity among nests, breeder abundance and reproductive synchrony have been proposed as primary factors responsible for enhanced colonial defence and foraging success, which, in turn, enhance reproductive success. Whether these factors function synergistically or antagonistically remains, however, an open question due to the absence of an integrated analysis of their effects on fitness. We studied a large population of the Lesser Kestrel, Falco naumanni, a facultative colonial species, breeding in colonies of different sizes in their typical pseudo-steppe habitat. We quantified both the singu…
Current practice in managing patients on anticoagulants and/or antiplatelet agents around the time of gastrointestinal endoscopy -- a nation-wide sur…
2004
Anticoagulants and antiplatelet agents are widely used in the prophylaxis and management of thromboembolic and cardiovascular diseases. Gastrointestinal bleeding is a well-known complication of these agents. Modification of anticoagulant and antiplatelet therapy is often required in patients undergoing surgical procedures and specific recommendations for the perioperative period have been issued. Fewer data exist with regard to the use of these agents around the time of endoscopic procedures. A survey of the American Society for Gastrointestinal Endoscopy (ASGE), performed several years ago, showed a wide variation between endoscopists in the management of anticoagulants and antiplatelet ag…