1,720,999 research outputs found
Role of the Oral Beta-Lactams in the Treatment of Exacerbations of Chronic Bronchitis: Critical Analysis and Therapeutic Recommendations
No full textThe GIARIR study group has made a critical analysis of the most recent scientific literature on acute bacterial exacerbations of chronic bronchitis (ABECB) with the aim of proposing therapeutic recommendations applicable to the current epidemiological situation in Italy. The international literature has indicated the scarcity of studies on the treatment of ABECB compared to an abundance of information regarding chronic obstructive pulmonary disease (COPD), of which ABECB is often considered the initial ore predisposing stage, even though a precise evolutionary correlation between these pathologies has not yet been demonstrated.
ABECB is the principle cause of doctor visits, hospitalization and death in COPD patients. The natural course of the disease is characterized by the appearance of exacerbation episodes (a mean of two yearly). For this reason it is indispensable to prevent exacerbations, to treat them as quickly as possible, in order to minimize their negative effects on the respiratory tract and the patient's general health.
The routine use of antibiotic therapy is controversial because at least 20% of exacerbations do not have an infectious origin and about 30% are viral. In most cases the choice of antibiotic is empiric, in both ABECB patients without risk factors (mild form) and in those with risk factors such as cigarette smoking or constant exposure to air pollutants (moderate form). For these reasons it is necessary to keep up to date on the local and regional bacteria etiological situation and to be aware of antibiotic resistance patterns for the most commonly involved pathogens.
An analysis of the most recent information in Italy has confirmed the involvement of the terrible three bacterial species Haemophilus influenzae, Moraxella catarrhalis and Streptococcus pneumoniae as the cause of 85-95% of ABECB cases, as well as an increase in resistance to various classes of molecules by all the respiratory pathogens. On the basis of the known resistance patterns in Italy, some antibiotics are no longer considered first choice for empiric therapy such as the unprotected beta-lactams, tetracycline, trimethoprim/sulfamethoxazole and the macrolides) which should be used only after antibiotic susceptibility testing indicates they are still active against the pathogens. The epidemiological picture of bacterial resistance in Italy has greatly restricted the choice of antibiotics which can be used for this type of infection, justifying interest in the oral beta-lactams which have the highest therapeutic index and are first choice therapy against bacterial exacerbations of chronic bronchitis. Included in this group are amoxicillin-clavulanate and the new cephem molecule, cefditoren, which has been available in Italy since 2008. Thanks to its good pharmacokinetics and pharmacodynamics as well as clinical performance, cefditoren may be considered a drug of choice against exacerbations of chronic bronchitis
A comparative study between spermine oxidase and bovine serum amine oxidase in differential scanning calorimetry and on cytotoxicity on cancer cell lines
No full textSpermine oxidase (SMO) is a FAD-containing enzyme while bovine serum amine-oxidase (BSAO) is a copper amine oxidase and both are able to oxidize polyamines. They play a dominant role in the highly regulated mammalian polyamines catabolism. Spermine oxidase specifically oxidizes spermine (SPM) producing spermidine (SPD), the reactive oxygen species H2O2 and the aldehyde 3-aminopropanal, each with the potential to produce cellular damages and pathologies (1). BSAO deaminates SPM and SPD to H2O2, aldehyde acrolein and ammonia. Since SPM represents a common substrate for SMO and BSAO enzymatic activities, a comparative study was performed on both enzymes in presence of SPM on several tumor cell lines melanoma (M14) and colon adenocarcinoma (LoVo) wild type and their MDR counterparts. SPM is a tetramine that plays mandatory roles in several cell functions, such as DNA synthesis, cellular proliferation, modulation of ion channels function and cellular signaling (1). Our previous studies demonstrated that BSAO and SPM added to human cancer cells induce cytotoxicity and overcome the MDR phenotype (2). We have performed in vitro experiments treating the above human cancer cell lines both phenotype wild type and MDR with SMO in presence of several concentrations of SPM (0-80 μM) for 60 min at 37°C. Cytotoxicity induced by SPM oxidation metabolites, such as H2O2 and the aldehyde 3-aminopropanal, was greater in MDR cells than in the corresponding wild-type ones (WT), maybe due to an increased mitochondrial activity. To get structural information a comparative study was also carried out on both enzymes, by differential Scanning Calorimetry (DSC) (3). The thermal stability of BSAO and SMO is studied by differential scanning calorimetry with a MicroCal MC-2D instrument. Differential scanning calorimetry permits detection of overall changes in protein structure correlated with changes in thermal stability of one or more calorimetric domains. This is particularly important in the case of BSAO and SMO, proteins for which only a little structural information is available. Our previous studies demonstrated that the thermal denaturation profile of the dimeric BSAO is characterized by three distinct endothermic peaks (Tm 58°C, 71.3°C, 77.9°C) (3). The deconvolution of the thermal profile required five two-state transitions, revealed for the dimeric protein a five domain structure, while the monomeric SMO displays one single, endothermic peak (Tm 63°C). The peak may be deconvoluted into two transitions and reveals the presents of two non similar size calorimetric domains: the lowest temperature domain is described by a non two-state transition and the highest temperature domain is described by a two-state transition. The thermal denaturation is irreversible after heating to 100°C.
Since the treatments with BSAO/SPM and SMO/SPM increased the amount of reactive oxygen species (ROS) inside the cells, higher in MDR than WT ones, we hypothesize that the enhancement of amine oxidase activity in tissues, undergoing pathological proliferative phenomena, may reasonably be exploited in the treatment of neoplastic diseases, mainly against MDR tumors.
References:
1- Cervelli M, Amendola R, Polticelli F, Mariottini P (2012). Spermine oxidase ten years later , AminoAcids 42 :441-450
2-Agostinelli, E., Condello, M., Molinari, A., Tempera, G., Viceconte, N., Arancia, G. (2009)
Cytotoxicity of spermine oxidation products to multidrug resistant melanoma M14 ADR2 cells:
Sensitization by the MDL 72527 lysosomotropic compound
International Journal of Oncology 35: 485-498
3) Giartosio A, Agostinelli E and Mondovì B (1988). Domains in bovine serum amine oxidase.
Biochem. Biophys. Res. Comm. 154: 66-72
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
The role of copper amine oxidases in the metabolism of polyamines and their therapeutic implications
No full text- …
