305,232 research outputs found
Sviluppo in silico di inibitori dello chaperone Hsp90 a potenziale interesse terapeutico
No full textThe molecular chaperone heat shock protein (HSP) 90, in the last years had a leading role as an anticancer drug target because of its importance in maintaining the conformation, stability and function of key oncogenic client proteins involved in signal transduction pathways leading to proliferation, cell cycle progression and apoptosis, as well as other features of the malignant phenotype such as invasion, angiogenesis and metastasis. This project focuses on developing new drug - like compound that show Hsp90 inhibitor activity, mainly by utilizing computational methodologies based on crystallographic structure. During the project were developed and tested new methodologies like a topological similarity analysis and a specific scoring function, that was parameterized on Hsp90 directlyLo chaperone Hsp90 si è affermato in questi ultimi anni come un interessante bersaglio terapeutico per svariate patologie umane. Tra tutte, molte tipologie di neoplasie maligne, in cui l’eccessiva attività di questa macchina molecolare consente il mantenimento della vitalità delle cellule trasformate, pur in presenza di gravi alterazioni del genoma e del tradotto proteico. Da ricordare inoltre, l’implicazione di questa proteina in patologie neurodegenerative quali la malattia di Alzheimer e di Parkinson e, da recenti scoperte, anche nella sclerosi multipla e nell’atrofia muscolare spinale e bulbare. Questo progetto mira ad indagare lo chaperone mediante metodologie computazionali, con fine ultimo quello di potersi inserire all’interno di un processo di drug discovery, che possa portare allo sviluppo di nuove molecole, o al recupero di molecole già esistenti, con attività inibitoria nei confronti di questa proteina. Per fare questo, ho cercato di ottimizzare un protocollo di virtual screening che fosse in grado di trovare, nel caso fossero presenti all’interno dei database analizzati, delle molecole attive sul bersaglio. Inoltre ho adottato alcune strategie innovative per andare a selezionare i database di ligandi in modo da massimizzare le possibilità di successo. Sono stati applicati metodi di analisi delle similarità topologiche delle proteine ed è stata parametrizzata una scoring function specificamente su Hsp90. Tutto questo è stato permesso dalla grande abbondanza di dati sulle strutture cristallografiche risolte ai raggi X, che da un lato hanno favorito il lavoro, mettendo a disposizione le strutture di molti inibitori noti; ma dall’altro hanno reso complessa la scelta di un modello di partenza, su cui basare in seguito il protocollo di docking molecolare
In vitro assessment of mononuclear leukocyte aggregation in response to sodium arachidonate and calcium ionophore A23187 : comparison with polymorphonuclear leukocytes
No full textThe effects of ionophore A23187 and sodium arachidonate (AASS) on mononuclear leukocyte (MNL) aggregation were evaluated and the results compared to those obtained with similarly challenged polymorphonuclear leukocytes (PMN). MNL aggregated in response to both ionophore A23187 (8-40 microM f.c.) and AASS (0.05-0.5 mM f.c.) and the response was comparable to that of similarly challenged PMN. The AASS induced aggregation of the two leukocyte subpopulations was inhibited by the presence of bovine serum albumin (BSA) in the incubation media and by calcium exogenously added. In contrast, this cation stimulated ionophore induced aggregation. When PMN and MNL aggregation was induced by AASS, a marked release of lactic dehydrogenase (LDH) was detected. The thromboxane-synthetase inhibitor UK 37248, inhibited both leukocyte aggregation and LDH release. When the response of leukocytes from male and female subjects was compared, in terms of aggregation, it appeared that the response of PMN from female volunteers was higher than that of PMN isolated from male donors, whereas no sex-related difference was detected when MNL aggregation was evaluated
Differential effects of aspirin and indomethacin on platelet and leukocyte thromboxane A2 formation
No full textIn this study, the in vitro inhibitory effects of aspirin and indomethacin on the arachidonic acid induced thromboxane B2 formation by human leukocytes, are evaluated. The results are compared to those obtained using similarly challenged human washed platelets. Acetylsalicylic acid inhibition, calculated as IC50 by a dose-response curve, is more than ten fold higher for leukocytes vs platelets. In fact, a concentration of aspirin as low as 5 microM almost completely suppresses thromboxane B2 formation by washed platelets, whereas a concentration of 50 microM is necessary to achieve the same inhibition with leukocytes. Indomethacin (0.001-100 microM), incubated with platelet and leukocyte suspensions acts similarly to aspirin. Leukocyte and platelet cyclooxygenases are, therefore, differently affected by both aspirin and indomethacin. These differences may be relevant in the understanding of the wide divergence between the aspirin doses used in thrombosis prevention and in the treatment of inflammatory disease
Effects of tenoxicam on superoxide anion formation, β-glucuronidase release and fMLP binding in human neutrophils : Comparison with other NSAIDs
No full textNon-steroidal anti-inflammatory drugs (NSAIDs) are considered to exert their activity by interfering with the generation of arachidonate metabolites in various cells, mainly in neutrophils and monocytes. The inhibition of cellular cyclooxygenase enzyme, however, does not always correlate with the in vivo activity of these drugs. Recent evidence indicates that several NSAIDs may interfere with the stimulus-response coupling of inflammatory cells. In this study, the effects of tenoxicam, an oxicam derivative with a thienothiazine structure, on neutrophil activation were evaluated by the assessment of the following parameters: (1) superoxide anion generation by neutrophils and whole blood stimulated with N-formyl-methionyl-leucyl-phenylalanine (fMLP), the calcium ionophore A23187 and serum treated zymosan (STZ); (2) beta-glucuronidase release from neutrophils stimulated with fMLP, A23187 and STZ; (3) binding of [3H]fMLP to intact neutrophils. The results were compared to those obtained using piroxicam and diclofenac. Tenoxicam, added in vitro to whole blood, at concentrations ranging between 10(-5) and 3 x 10(-4) M, significantly inhibited the generation of superoxide anion induced by fMLP, A23187 and STZ. The activity of tenoxicam on whole blood was similar to that of piroxicam, whereas diclofenac had only minimal effects on this experimental system. In isolated cells tenoxicam inhibited the generation of superoxide anion induced by A23187 and STZ. In addition, at the 3 x 10(-4) M concentration, tenoxicam and diclofenac similarly inhibited O2- generation by neutrophils stimulated with fMLP, whereas piroxicam only minimally affected this parameter. Tenoxicam also slightly, but not significantly, inhibited beta-glucuronidase release by isolated neutrophils induced by all the agonists used. Specific binding of [3H]fMLP to neutrophils was inhibited by the three NSAIDs tested in a dose-dependent fashion and tenoxicam was the most potent. The affinities (Kd) of tenoxicam, piroxicam and diclofenac were 1.11, 1.80 and 2.70 x 10(-5) M, respectively. The mechanism of inhibition of [3H]fMLP binding by tenoxicam was non-competitive. It is concluded that tenoxicam, at concentrations achievable in plasma at steady state, effectively inhibits some of the processes involved in neutrophil activation, which bear some relevance in the inflammatory disease
Vitamin E influences the effects of fish oil on fatty acids and eicosanoid production in plasma and circulating cells in the rat
No full textAn EPA enriched oil (MaxEPA, Seven Seas, U.K. containing 18% EPA and 12% DHA) alone or supplemented with 10 mg/ml/alpha tocopherol, was administered by gastric intubation at the dose of 3.2 ml/kg/day for a period of eight weeks to male rats fed a standard diet. An additional group of animals was treated with the same amount of olive oil. The administration of MaxEPA alone resulted, as expected, in accumulation of EPA and reduction of AA levels in plasma, platelet, red blood cell and PMNL phospholipids, when compared to values in the olive oil group. In addition, levels of linoleic acid were elevated, suggesting inhibition of the conversion of linoleic to arachidonic acid. Formation of i.r. TxB2 by stimulated PRP, of i.r. 6-keto-PGF1 alpha by perfused aortas, and of IR LTB4 and C4 by stimulated PMNL were reduced, but production of superoxide anion by PMNL was enhanced by MaxEPA treatment vs the olive oil treatment. Supplementation of MaxEPA with vitamin E caused a smaller reduction of 20:4 levels and a smaller increase of 20:5 levels in plasma and cell phospholipids and modified the effects of MaxEPA on eicosanoid and superoxide anion production, suggesting that lipid peroxidation may mediate some of the biological effects of omega 3 fatty acids
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Inhibition of human neutrophil aggregation by albumin. Relationship with cytoskeleton reorganization
No full textAlbumin, at concentration normally present in plasma (~ 600 μM), significantly inhibited leukotriene B4 formation induced by a receptor mediated (fMet-Leu-Phe) and a receptor independent (calcium ionophore A23187) stimuli in human neutrophils. The inhibition of leukotriene B4 synthesis was accompanied by a concomitant reduction of neutrophil aggregation. In addition, this plasma protein prevented the increase in F-actin content of neutrophils stimulated with fMet-Leu-Phe and A23187, thus suppressing actin polymerization. These data indicate that albumin profoundly affects biochemical and functional aspects of neutrophils suggesting, for this plasma protein, a regulatory role in the overall pattern of the inflammatory reaction
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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