223 research outputs found

    Experimental hyperleptinemia in neonatal rats leads to selective leptin responsiveness, hypertension, and altered myocardial function

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    The prevalence of obesity among pregnant women is increasing. Evidence from human cohort studies and experimental animals suggests that offspring cardiovascular and metabolic function is compromised through early life exposure to maternal obesity. Previously, we reported that juvenile offspring of obese rats develop sympathetically mediated hypertension associated with neonatal hyperleptinemia. We have now addressed the hypothesis that neonatal exposure to raised leptin in the immediate postnatal period plays a causal role. Pups from lean Sprague-Dawley rats were treated either with leptin (3 mg/kg IP) or with saline twice daily from postnatal day 9 to 15 to mimic the exaggerated postnatal leptin surge observed in offspring of obese dams. Cardiovascular function was assessed by radiotelemetry at 30 days, and 2 and 12 months. In juvenile (30 days) leptin-treated rats, hearts were heavier and night-time (active period) systolic blood pressure was raised (mm Hg; meanΒ±SEM: male leptin-treated, 132Β±1 versus saline-treated, 119Β±1, n=6, P<0.05; female leptin-treated, 132Β±2 versus saline-treated, 119Β±1, n=6, P<0.01), and the pressor response to restraint stress and leptin challenge increased compared with saline-treated rats. Heart rate variability demonstrated an increased low:high frequency ratio in 30-day leptin-treated animals, indicative of heightened sympathetic efferent tone. Echocardiography showed altered left ventricular structure and systolic function in 30-day female leptin versus saline-treated rats. These disorders persisted to adulthood. In isolated hearts, contractile function was impaired at 5 months in male leptin-treated rats. Exogenously imposed hyperleptinemia in neonatal rats permanently influences blood pressure and cardiac structure and function

    Towards an effective potential for the monomer, dimer, hexamer, solid and liquid forms of hydrogen fluoride

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    We present an attempt to build up a new two-body effective potential for hydrogen fluoride, fitted to theoretical and experimental data relevant not only to the gas and liquid phases, but also to the crystal. The model is simple enough to be used in Molecular Dynamics and Monte Carlo simulations. The potential consists of: a) an intra-molecular contribution, allowing for variations of the molecular length, plus b) an inter-molecular part, with three charged sites on each monomer and a Buckingham "exp-6" interaction between fluorines. The model is able to reproduce a significant number of observables on the monomer, dimer, hexamer, solid and liquid forms of HF. The shortcomings of the model are pointed out and possible improvements are finally discussed.Comment: LaTeX, 24 pages, 2 figures. For related papers see also http://www.chim.unifi.it:8080/~valle

    First Universities Allied for Essential Medicines (UAEM) Neglected Diseases and Innovation Symposium

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    Universities Allied for Essential Medicines organized its first Neglected Diseases and Innovation Symposium to address expanding roles of public sector research institutions in innovation in research and development of biomedical technologies for treatment of diseases, particularly neglected tropical diseases. Universities and other public research institutions are increasingly integrated into the pharmaceutical innovation system. Academic entities now routinely undertake robust high-throughput screening and medicinal chemistry research programs to identify lead compounds for small molecule drugs and novel drug targets. Furthermore, product development partnerships are emerging between academic institutions, non-profit entities, and biotechnology and pharmaceutical companies to create diagnostics, therapies, and vaccines for diseases of the poor. With not for profit mission statements, open access publishing standards, open source platforms for data sharing and collaboration, and a shift in focus to more translational research, universities and other public research institutions are well-placed to accelerate development of medical technologies, particularly for neglected tropical diseases

    Primitive computations in speech processing

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    Previous research suggests that artificial-language learners exposed to quasi-continuous speech can learn that the first and the last syllables of words have to belong to distinct classes (e.g., Endress & Bonatti, 2007; PeΓ±a, Bonatti, Nespor, & Mehler, 2002). The mechanisms of these generalizations, however, are debated. Here we show that participants learn such generalizations only when the crucial syllables are in edge positions (i.e., the first and the last), but not when they are in medial positions (i.e., the second and the fourth in pentasyllabic items). In contrast to the generalizations, participants readily perform statistical analyses also in word middles. In analogy to sequential memory, we suggest that participants extract the generalizations using a simple but specific mechanism that encodes the positions of syllables that occur in edges. Simultaneously, they use another mechanism to track the syllable distribution in the speech streams. In contrast to previous accounts, this model explains why the generalizations are faster than the statistical computations, require additional cues, and break down under different conditions, and why they can be performed at all. We also show that that similar edge-based mechanisms may explain many results in artificial-grammar learning and also various linguistic observations

    Controversy surrounding the increased expression of TGFΞ²1 in asthma

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    Asthma is a waxing and waning disease that leads to structural changes in the airways, such as subepithelial fibrosis, increased mass of airway smooth muscle and epithelial metaplasia. Such a remodeling of the airways futher amplifies asthma symptoms, but its etiology is unknown. Transforming growth factor Ξ²1 is a pleiotropic cytokine involved in many fibrotic, oncologic and immunologic diseases and is believed to play an essential role in airway remodeling that occurs in asthmatic patients. Since it is secreted in an inactive form, the overall activity of this cytokine is not exclusively determined by its level of expression, but also by extensive and complex post-translational mechanisms, which are all importanin modulating the magnitude of the TGFΞ²1 response. Even if TGFΞ²1 upregulation in asthma is considered as a dogma by certain investigators in the field, the overall picture of the published litterature is not that clear and the cellular origin of this cytokine in the airways of asthmatics is still a contemporaneous debate. On the other hand, it is becoming clear that TGFΞ²1 signaling is increased in the lungs of asthmatics, which testifies the increased activity of this cytokine in asthma pathogenesis. The current work is an impartial and exhaustive compilation of the reported papers regarding the expression of TGFΞ²1 in human asthmatics. For the sake of comparison, several studies performed in animal models of the disease are also included. Inconsistencies observed in human studies are discussed and conclusions as well as trends from the current state of the litterature on the matter are proposed. Finally, the different points of regulation that can affect the amplitude of the TGFΞ²1 response are briefly revised and the possibility that TGFΞ²1 is disregulated at another level in asthma, rather than simply in its expression, is highlighted

    Rhinovirus-induced basic fibroblast growth factor release mediates airway remodeling features

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    BACKGROUND: Human rhinoviruses, major precipitants of asthma exacerbations, induce lower airway inflammation and mediate angiogenesis. The purpose of this study was to assess the possibility that rhinoviruses may also contribute to the fibrotic component of airway remodeling. METHODS: Levels of basic fibroblast growth factor (bFGF) mRNA and protein were measured following rhinovirus infection of bronchial epithelial cells. The profibrotic effect of epithelial products was assessed by DNA synthesis and matrix metalloproteinase activity assays. Moreover, epithelial cells were exposed to supernatants from cultured peripheral blood mononuclear cells, obtained from healthy donors or atopic asthmatic subjects and subsequently infected by rhinovirus and bFGF release was estimated. bFGF was also measured in respiratory secretions from atopic asthmatic patients before and during rhinovirus-induced asthma exacerbations. RESULTS: Rhinovirus epithelial infection stimulated mRNA expression and release of bFGF, the latter being positively correlated with cell death under conditions promoting rhinovirus-induced cytotoxicity. Supernatants from infected cultures induced lung fibroblast proliferation, which was inhibited by anti-bFGF antibody, and demonstrated increased matrix metalloproteinase activity. Rhinovirus-mediated bFGF release was significantly higher in an in vitro simulation of atopic asthmatic environment and, importantly, during rhinovirus-associated asthma exacerbations. CONCLUSIONS: Rhinovirus infection induces bFGF release by airway epithelium, and stimulates stroma cell proliferation contributing to airway remodeling in asthma. Repeated rhinovirus infections may promote asthma persistence, particularly in the context of atopy; prevention of such infections may influence the natural history of asthma
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