3,414 research outputs found

    Optimal metabolic strategies for microbial growth in stationary random environments

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    In order to grow in any given environment, bacteria need to collect information about the medium composition and implement suitable growth strategies by adjusting their regulatory and metabolic degrees of freedom. In the standard sense, optimal strategy selection is achieved when bacteria grow at the fastest rate possible in that medium. While this view of optimality is well suited for cells that have perfect knowledge about their surroundings (e.g. nutrient levels), things are more involved in uncertain or fluctuating conditions, especially when changes occur over timescales comparable to (or faster than) those required to organize a response. Information theory however provides recipes for how cells can choose the optimal growth strategy under uncertainty about the stress levels they will face. Here we analyse the theoretically optimal scenarios for a coarse-grained, experiment-inspired model of bacterial metabolism for growth in a medium described by the (static) probability density of a single variable (the `stress level'). We show that heterogeneity in growth rates consistently emerges as the optimal response when the environment is sufficiently complex and/or when perfect adjustment of metabolic degrees of freedom is not possible (e.g. due to limited resources). In addition, outcomes close to those achievable with unlimited resources are often attained effectively with a modest amount of fine-tuning. In other terms, heterogeneous population structures in complex media may be rather robust with respect to the amounts of cellular resources available to probe the environment and adjust reaction rates

    Genes and primary headaches: discovering new potential therapeutic targets

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    Genetic studies have clearly shown that primary headaches (migraine, tension-type headache and cluster headache) are multifactorial disorders characterized by a complex interaction between different genes and environmental factors. Genetic association studies have highlighted a potential role in the etiopathogenesis of these disorders for several genes related to vascular, neuronal and neuroendocrine functions. A potential role as a therapeutic target is now emerging for some of these genes. The main purpose of this review is to describe new advances in our knowledge regarding the role of MTHFR, KCNK18, TRPV1, TRPV3 and HCRTR genes in primary headache disorders. Involvement of these genes in primary headaches, as well as their potential role in the therapy of these disorders, will be discussed

    Relationship between fitness and heterogeneity in exponentially growing microbial populations

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    Despite major environmental and genetic differences, microbial metabolic networks are known to generate consistent physiological outcomes across vastly different organisms. This remarkable robustness suggests that, at least in bacteria, metabolic activity may be guided by universal principles. The constrained optimization of evolutionarily motivated objective functions, such as the growth rate, has emerged as the key theoretical assumption for the study of bacterial metabolism. While conceptually and practically useful in many situations, the idea that certain functions are optimized is hard to validate in data. Moreover, it is not always clear how optimality can be reconciled with the high degree of single-cell variability observed in experiments within microbial populations. To shed light on these issues, we develop an inverse modeling framework that connects the fitness of a population of cells (represented by the mean single-cell growth rate) to the underlying metabolic variability through the maximum entropy inference of the distribution of metabolic phenotypes from data. While no clear objective function emerges, we find that, as the medium gets richer, the fitness and inferred variability for Escherichia coli populations follow and slowly approach the theoretically optimal bound defined by minimal reduction of variability at given fitness. These results suggest that bacterial metabolism may be crucially shaped by a population-level trade-off between growth and heterogeneity

    Overview on the Link Between the Complement System and Auto-Immune Articular and Pulmonary Disease

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    Complement system (CS) dysregulation is a key factor in the pathogenesis of different autoimmune diseases playing a central role in many immune innate and adaptive processes. Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by ta breach of self -tolerance leading to a synovitis and extra-articular manifestations. The CS is activated in RA and seems not only to mediate direct tissue damage but also play a role in the initiation of RA pathogenetic mechanisms through interactions with citrullinated proteins. Interstitial lung disease (ILD) represents the most common extra-articular manifestation that can lead to progressive fibrosis. In this review, we focused on the evidence of CS dysregulation in RA and in ILD, and highlighted the role of the CS in both the innate and adaptive immune responses in the development of diseases, by using idiopathic pulmonary fibrosis as a model of lung disease. As a proof of concept, we dissected the evidence that several treatments used to treat RA and ILD such as glucocorticoids, pirfenidone, disease modifying antirheumatic drugs, targeted biologics such as tumor necrosis factor (TNF)-inhibitors, rituximab, tocilizumab, and nintedanib may act indirectly on the CS, suggesting that the CS might represent a potential therapeutic target in these complex diseases

    Clinical peculiarities of tuberculosis

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    The ongoing spread of tuberculosis (TB) in poor resource countries and the recently increasing incidence in high resource countries lead to the need of updated knowledge for clinicians, particularly for pediatricians. The purpose of this article is to provide an overview on the most important peculiarities of TB in children. Children are less contagious than adults, but the risk of progression to active disease is higher in infants and children as compared to the subsequent ages. Diagnosis of TB in children is more difficult than in adults, because few signs are associated with primary infection, interferon-gamma release assays and tuberculin skin test are less reliable in younger children, M. tuberculosis is more rarely detected in gastric aspirates than in smears in adults and radiological findings are often not specific. Treatment of latent TB is always necessary in young children, whereas it is recommended in older children, as well as in adults, only in particular conditions. Antimycobacterial drugs are generally better tolerated in children as compared to adults, but off-label use of second-line antimycobacterial drugs is increasing, because of spreading of multidrug resistant TB worldwide. Given that TB is a disease which often involves more than one member in a family, a closer collaboration is needed between pediatricians and clinicians who take care of adults

    Self-efficacy for coping. Utility of the Cancer behavior inventory (Italian) for use in palliative care

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    Background: Newer models of palliative and supportive cancer care view the person as an active agent in managing physical and psychosocial challenges. Therefore, personal efficacy is an integral part of this model. Due to the lack of instruments in Italian to assess coping self-efficacy, the present study included the translation and validation of the Italian version of the Cancer Behavior Inventory-Brief (CBI-B/I) and an initial analysis of the utility of self-efficacy for coping in an Italian sample of palliative care patients. Methods: 216 advanced cancer patients who attended palliative care clinics were enrolled. The CBI-B/I was administered along with the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30), the Mini Mental Adjustment to Cancer Scale (Mini-MAC), the Cancer Concerns Checklist (CCL), and the Hospital Anxiety and Depression Scale (HADS). The Eastern Cooperative Oncology Group Performance Status (ECOG-PS) ratings of functional capacity were completed by physicians. Results: Factor analysis confirmed that the structure of the CBI-B/I was consistent with the English version. Internal consistency reliability and significant correlations with the EORTC QLQ-C30, Mini-MAC, and HADS supported the concurrent validity of the CBI-B/I. Differences in CBI-B/I scores for high versus low levels of the CCL and ECOG-PS supported the clinical utility of the CBI-B/I. Conclusions: The CBI-B/I has strong psychometric properties and represents an important addition to newer model of palliative and supportive care. In order to improve clinical practice, the CBI-B/I could be useful in identifying specific self-efficacy goals for coping in structured psychosocial intervention

    Antimicrobial Resistant Staphylococcus Species Colonization in Dogs, Their Owners, and Veterinary Staff of the Veterinary Teaching Hospital of Naples, Italy

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    This study aimed to identify Staphylococcus species isolated from nasal swabs of both healthy and diseased dogs, and those of human origin, obtained from nasal swabs of both owners and veterinary staff. Firstly, pet owners were requested to complete a questionnaire relating to the care and relationship with their pets, whose results mainly showed a statistically significant higher frequency of hand washing in diseased dogs’ owners than in healthy dogs’ owners. Canine nasal swabs were obtained from 43 diseased dogs and 28 healthy dogs, while human nasal swabs were collected from the respective dogs’ owners (71 samples) and veterinary staff (34 samples). The isolation and identification of Staphylococcus spp. were followed by disk diffusion method to define the antimicrobial resistance profiles against 18 different molecules. Staphylococcus pseudintermedius was the most frequent isolated strain in both diseased (33.3%) and healthy (46.1%) dogs. Staphylococcus epidermidis was the most frequent isolated bacterium in diseased dogs’ owners (66.6%), while in nasal samples of healthy dogs’ owners, the same frequency of isolation (38.4%) was observed for both Staphylococcus epidermidis and Staphylococcus aureus. All the isolated strains showed good susceptibility levels to the tested antimicrobials; however, the carriage of oxacillin-resistant strains was significantly higher in diseased dogs than in healthy ones (71% and 7.7%, respectively). Only in three cases the presence of the same bacterial species with similar antimicrobial resistance profiles in dogs and their owners was detected, suggesting the potential bacterial transmission. In conclusion, this study suggests potential transmission risk of staphylococci from dogs to humans or vice versa, and highlights that the clinical relevance of Staphylococcus pseudintermedius transmission from dog to human should not be underestimated, as well as the role of Staphylococcus aureus from human to dog transmission

    The detail is more pleasant than the whole: global and local prime affect esthetic appreciation of artworks showing whole-part ambiguity

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    Esthetic experience is the result of the coordination of different cognitive processes. It has been widely reported that top-down processes of orienting of attention interact with bottom-up perceptual facilitation occurring during esthetic experience of artworks. Here we use whole-part ambiguity as a tool to test the effect of global and local prime on esthetic appreciation of complex visual artworks. To this aim 139 healthy young individuals completed an esthetic judgment of Arcimboldo’s ambiguous artworks, which were preceded by a local or global prime. Their perceptual style was also assessed using a Navon task. We found that local prime significantly enhanced esthetic appreciation of ambiguous portraits. Also, we found that prime level interacted with individual’s perceptual style: participants showing local perceptual style liked less ambiguous portraits when they were preceded by global prime. Overall, the present findings shed some light on the processes involved in esthetic experience, pointing towards a pivotal role of re-direction of attention towards perceptual features of the artworks and its interaction with individual factors, such as perceptual style

    The Long-Period seismicity before and during the volcanic crises: examples from two case studies

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    The Long-Period (LP) seismicity is common at active volcanoes and is usually modeled as due to pressurized magmatic fluids flowing through rock cavities. These signals are sensitive to the thermodynamic conditions of the magma-gas mixture in the shallow plumbing system and can thus be adopted as “detectors” of an impelling eruption. We found that at Stromboli (Italy) before and/or during recent volcanic crises the LP events can occur in swarms, which show different statistics, higher energy and shallower location than the stationary LP activity. We imputed the LP swarms to a quick depressurization (|ΔP|≥105 Pa) of the shallowest (<0.8 km) part of the conduit. At Shishaldin (Alaska) the 2004 eruption is anticipated by a migration towards the surface of the LP source, which moves from ~8 km to ≾5 km below the crater rim. By simple assumptions, we modeled this source change as produced by an increase of the confining pressure within the plumbing system of ~5x107 Pa, possibly induced by an upward migration of ~108-1010 kg of magma
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