119 research outputs found

    Mosquito Populations from Eastern South Dakota During 2001 and 2002

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    In 2001, the South Dakota Department of Health initiated a program to monitor mosquitoes in South Dakota for the presence of the West Nile Virus. During the first year (2001), a pilot survey was conducted near Brookings, SD. To collect mosquitoes, CDC miniture light traps were used without carbondioxide baiting, beginning on July 3 and ending on August 2, 2001. Results from this small study (total of 2,042 mosquitoes during 10 collection days) showed that the most common mosquotes were Aedes vexans (88.2%), Culex tarsalis, (5.2%), and Aedes dorsalis (4.9%). An additional survey was conducted during the summer of 2002 focusing on 8 different sites (Brandon, Brookings, Huron, North Sioux City, Oak Lake Field Station, Watertown, Waubay and Yankton) in eastern South Dakota. Mosquitoes were collected with the same traps used for 2001, however, the traps were baited with carbon diaoxide (dry ice). Trapping began on June 1 and ended on September 1, 2002. A total of 18,971 mosquitoes were collected from the 8 sites during the 127 trapping days of this survey. From this population, 21 different mosquito species from 8 different genera were identified. The vast majority of mosquitoes were Aedes vexans (86.3%), but Culex tarsalis was also present in significant numbers (7.2%). Aedes vexans populations varied to a greater degree during the summer than did Culex tarsalis. The public’s perceptions of the danger of West Nile Virus transmission is probably more determined by Aedes population than by Culex populations even though Aedes likely plays little or no role in the transmission of this disease

    Fluctuations and differential contraction during regeneration of Hydra vulgaris tissue toroids

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    We studied regenerating bilayered tissue toroids dissected from Hydra vulgaris polyps and relate our macroscopic observations to the dynamics of force-generating mesoscopic cytoskeletal structures. Tissue fragments undergo a specific toroid-spheroid folding process leading to complete regeneration towards a new organism. The time scale of folding is too fast for biochemical signalling or morphogenetic gradients which forced us to assume purely mechanical self-organization. The initial pattern selection dynamics was studied by embedding toroids into hydro-gels allowing us to observe the deformation modes over longer periods of time. We found increasing mechanical fluctuations which break the toroidal symmetry and discuss the evolution of their power spectra for various gel stiffnesses. Our observations are related to single cell studies which explain the mechanical feasibility of the folding process. In addition, we observed switching of cells from a tissue bound to a migrating state after folding failure as well as in tissue injury. We found a supra-cellular actin ring assembled along the toroid's inner edge. Its contraction can lead to the observed folding dynamics as we could confirm by finite element simulations. This actin ring in the inner cell layer is assembled by myosin- driven length fluctuations of supra-cellular {\alpha}-actin structures (myonemes) in the outer cell-layer.Comment: 19 pages and 8 figures, submitted to New Journal of Physic

    Runx1 promotes scar deposition and inhibits myocardial proliferation and survival during zebrafish heart regeneration.

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    Runx1 is a transcription factor that plays a key role in determining the proliferative and differential state of multiple cell types, during both development and adulthood. Here, we report how Runx1 is specifically upregulated at the injury site during zebrafish heart regeneration, and that absence of runx1 results in increased myocardial survival and proliferation, and overall heart regeneration, accompanied by decreased fibrosis. Using single cell sequencing, we found that the wild-type injury site consists of Runx1-positive endocardial cells and thrombocytes that induce expression of smooth muscle and collagen genes. Both these populations cannot be identified in runx1 mutant wounds that contain less collagen and fibrin. The reduction in fibrin in the mutant is further explained by reduced myofibroblast formation and upregulation of components of the fibrin degradation pathway, including plasminogen receptor annexin 2A as well as downregulation of plasminogen activator inhibitor serpine1 in myocardium and endocardium, resulting in increased levels of plasminogen. Our findings suggest that Runx1 controls the regenerative response of multiple cardiac cell types and that targeting Runx1 is a novel therapeutic strategy for inducing endogenous heart repair.BHF, Wellcome, MR

    Gradients versus Cycling in Genetic Selection Models

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    We review the hierarchy of (continuous time) selection models starting with the classical Fisher's viability selection model, and its generalizations when allowing mutations, recombination, sex-dependent viabilities, fertility selection and different mortality rates. We analyse the question in which way Fisher's "Fundamental Theorem of Natural Selection" and Kimura's Maximum Principle can be extended to these more general situations. It turns out that in many cases this is principally impossible since the dynamics becomes cycling or even chaotic

    Factors affecting the survival of patients with oesophageal carcinoma under radiotherapy in the north of Iran

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    Factors relevant to the survival of patients with oesophageal cancer under radiotherapy have been studied in northern Iran where its incidence is high. We conducted an analytical study using a historical cohort and information from the medical charts of patients with oesophageal cancer. Out of 523 patients referred to the Shahid Rajaii radiotherapy centre in Babolsar from 1992 to 1996, we followed 230 patients for whom an address was available in 1998. The frequency of prognostic factors among those not contacted was very similar to those included in the study. The data were analysed using survival analysis by the nonparametric method of Kaplan Meier and the Cox regression model to determine risk ratios (RR) of prognostic factors. Survival rates were 42% at 1 year, 21% at 2 years, and 8% at 5 years after diagnosis. Patients aged 50–64 were found to have poorer survival compared with those less than 50 (RR = 1.73, P = 0.03); the risk ratio for ages f = 65 was 1.88 (P = 0.03). Females had significantly better survival than males (RR = 0.71, P = 0.02). For each 100 rads dose of radiotherapy, the risk ratio was significantly decreased by 1% (RR = 0.99, P = 0.05); for each session of radiotherapy, the risk ratio was significantly decreased by 4% (RR = 0.96, P = 0.0001); for each square centimetre size of surface under radiotherapy, the risk ratio significantly increased (RR = 1.002, P = 0.04). We did not observe a significant difference on survival by histology, anatomical location of tumours, or type of treatment (P > 0.05). Prognosis is extremely poor. © 2001 Cancer Research Campaign http://www.bjcancer.co

    Sarcoidosis activates diverse transcriptional programs in bronchoalveolar lavage cells

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    Abstract Background Sarcoidosis is a multisystem immuno-inflammatory disorder of unknown etiology that most commonly involves the lungs. We hypothesized that an unbiased approach to identify pathways activated in bronchoalveolar lavage (BAL) cells can shed light on the pathogenesis of this complex disease. Methods We recruited 15 patients with various stages of sarcoidosis and 12 healthy controls. All subjects underwent bronchoscopy with lavage. For each subject, total RNA was extracted from BAL cells and hybridized to an Affymetrix U133A microarray. Rigorous statistical methods were applied to identify differential gene expression between subjects with sarcoidosis vs. controls. To better elucidate pathways differentially activated between these groups, we integrated network and gene set enrichment analyses of BAL cell transcriptional profiles. Results Sarcoidosis patients were either non-smokers or former smokers, all had lung involvement and only two were on systemic prednisone. Healthy controls were all non-smokers. Comparison of BAL cell gene expression between sarcoidosis and healthy subjects revealed over 1500 differentially expressed genes. Several previously described immune mediators, such as interferon gamma, were upregulated in the sarcoidosis subjects. Using an integrative computational approach we constructed a modular network of over 80 gene sets that were highly enriched in patients with sarcoidosis. Many of these pathways mapped to inflammatory and immune-related processes including adaptive immunity, T-cell signaling, graft vs. host disease, interleukin 12, 23 and 17 signaling. Additionally, we uncovered a close association between the proteasome machinery and adaptive immunity, highlighting a potentially important and targetable relationship in the pathobiology of sarcoidosis. Conclusions BAL cells in sarcoidosis are characterized by enrichment of distinct transcriptional programs involved in immunity and proteasomal processes. Our findings add to the growing evidence implicating alveolar resident immune effector cells in the pathogenesis of sarcoidosis and identify specific pathways whose activation may modulate disease progression

    Gradients for the evolution of bimatrix games

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    The evolutionary dynamics of bimatrix games is studied for rescaled partnership games and zero sum games. The former case leads to gradient systems. The selection equations for sexual and asexual reproduction of genotypes corresponding to mixed strategies are analysed. As examples, the origin of anisogamy and cyclic chases for predator-prey coevolution are studied
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