1,721,001 research outputs found
Opportunistic bacteria in implant infections Knowing them to plan their control - Editorial
No full textBetter general hygienic conditions, antibiotics, vaccines:
these are the three factors of prevention and therapy that
have eradicated many infective diseases, both of bacterial
and of viral etiology, in the last two centuries. But
infections are abreast of the times and seem unwilling to
abandon us. Our times have witnessed great technological
progress, with more and more frequent substitutions of
tissues and organs, either bare or engineered with living
cells. But prosthesis users are not only healthy people,
such as athletes treated for sport traumas, or young
women resorting to cosmetic surgery, but also and
especially patients with impaired immunological defenses,
who nowadays, because of the improvement in health
conditions and medical progress, are more numerous and
in need of implants, such as prostheses or artificial
organs: the elderly, diabetics, oncologic patients,
premature infants.
Thus, here a new hazard emerges, bacterial opportunism:
micro-organisms that, until few years ago, could be
considered mere saprophytes, habitual guests of skin and
mucosae, exhibit a peculiar attitude to cling to implant
materials and to infect the surrounding peri-prosthesis
tissues, often displaying an alarming antibiotic resistance.
In this regard, two genera cover a special role, the
genus Staphylococcus, enlisting numerous species usually
characterized as saprophytic, and the genus
Pseudomonas, with its diffuse nosocomial opportunistic
pathogen species Pseudomonas aeruginosa.
Staphylococcus aureus, Staphylococcus epidermidis
and a number of other coagulase-negative staphylococci
(CoNS) are progressively being indicated for their
pathogenic potential. In this context, coagulase-negative
staphylococci (CoNS) are playing a primary role. The large
diffusion in the environment, also including human skin
and mucosae, and the ability to colonize material surfaces
forming protective biofilms, have led some members of
this group of bacteria, among them in first place
Staphylococcus epidermidis, to become very common
nosocomial pathogens.
New emerging staphylococcal species are progressively
assuming a worrisome pathogenic behavior, affecting an
ample population of hospitalized patients. The rapid
adaptation of bacteria to new environmental niches,
combined with the increased number of immunocompromised
patients and with the large use of prosthetic
materials, still steadily growing in many medical fields, will
certainly favor the development of opportunistic infections
caused by these staphylococci, determining the
appearance of virulent pathogenic strains. Staphylococci,
as other bacteria, have the possibility to exchange genetic
material through mobile genetic elements, such as
plasmids and transposons.
Moreover, biofilms produced by Staphylococcus and
Pseudomanas genera play an important role in the spread of
antibiotic resistance. The high bacterial density and the
accumulated mobile genetic elements within biofilms provide
an ideal field for efficient horizontal gene transfer where
bacteria can exchange plasmids by conjugation or by
transposons carrying insertion elements. By these
mechanisms, within polymicrobic biofilms, resistance and
virulence factors may be passed among bacteria, transforming
apathogenic to highly virulent strains both within and beyond
species borders. Gene transfer between different species of
Pseudomonas were shown to occur at a significantly higher
rate in biofilms than under planktonic conditions.
The prevalence of virulence and antibiotic resistance
traits among opportunistic bacteria with different
pathogenicity is currently analyzed by molecular methods,
opening a new branch in the study of infectious diseases,
molecular epidemiology.
From these new studies, the concept emerges that
minor staphylococcal species could represent important
acceptors and reservoirs of antibiotic resistance genes
and virulence factors. At the same time ..
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
A glance at the role of exotoxins in opportunistic bacterial infections
No full textThe production and the mechanism of action of exotoxins from Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa are presented. The attack to the immune host's defenses is the main virulence factor of opportunistic bacteria in implant infections, favoring the invasion and
colonization of compromised periprosthesis tissues
Animal models of osteomyelitis
No full textThere are numerous reports in the literature using animal models of osteomyelitis for investigating pathogenesis, diagnosis, and treatment of bone infections. Rabbits, rats, and dogs are
commonly used animals, and, less frequently, chickens, guinea pigs, miniature pigs, goats, and sheep. Commonly used bones for creating local osteomyelitis include tibia, femur, and radius, and,
less frequently, mandible and spine. When designing a specific model, one should consider which animal and which bone will be used, which route for inoculation (either local injection or systemically through vascular injection), which bacterial species and how many bacteria should be applied, if and what sclerosing agent, foreign body or implant should be employed, and if local trauma is needed. Basic methods of evaluation include clinical observation, radiography, microbiology, and histology
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