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941.
Seroprevalence survey is the most practical method for accurately estimating infection attack rate (IAR) in an epidemic such as influenza. These studies typically entail selecting an arbitrary titer threshold for seropositivity (e.g. microneutralization [MN] 1∶40) and assuming the probability of seropositivity given infection (infection-seropositivity probability, ISP) is 100% or similar to that among clinical cases. We hypothesize that such conventions are not necessarily robust because different thresholds may result in different IAR estimates and serologic responses of clinical cases may not be representative. To illustrate our hypothesis, we used an age-structured transmission model to fully characterize the transmission dynamics and seroprevalence rises of 2009 influenza pandemic A/H1N1 (pdmH1N1) during its first wave in Hong Kong. We estimated that while 99% of pdmH1N1 infections became MN1∶20 seropositive, only 72%, 62%, 58% and 34% of infections among age 3–12, 13–19, 20–29, 30–59 became MN1∶40 seropositive, which was much lower than the 90%–100% observed among clinical cases. The fitted model was consistent with prevailing consensus on pdmH1N1 transmission characteristics (e.g. initial reproductive number of 1.28 and mean generation time of 2.4 days which were within the consensus range), hence our ISP estimates were consistent with the transmission dynamics and temporal buildup of population-level immunity. IAR estimates in influenza seroprevalence studies are sensitive to seropositivity thresholds and ISP adjustments which in current practice are mostly chosen based on conventions instead of systematic criteria. Our results thus highlighted the need for reexamining conventional practice to develop standards for analyzing influenza serologic data (e.g. real-time assessment of bias in ISP adjustments by evaluating the consistency of IAR across multiple thresholds and with mixture models), especially in the context of pandemics when robustness and comparability of IAR estimates are most needed for informing situational awareness and risk assessment. The same principles are broadly applicable for seroprevalence studies of other infectious disease outbreaks.  相似文献   
942.
Apo-calmodulin, a small soluble mainly α protein, is a calcium-dependent protein activator. Calcium binding affects the calmodulin conformation but also its stability. Calcium free form unfolds between 40 and 80 °C, whereas the calcium-saturated form is stable up to temperatures as high as 100 °C, forbidding comparison of the thermal unfolding pathways of the two forms. Thus, this paper focuses especially on the conformation of pressure-induced unfolding states of both forms of calmodulin, by combining small-angle neutron scattering (SANS) with biophysical techniques such as tyrosines and ANS fluorescence. In contrast to heat denaturation (Gibrat et al., BBA, 2012), the pressure denaturation of calmodulin is reversible up to pressures of 3000 bar (300 MPa). A pressure-induced compact intermediate state has been found for the two calmodulin forms, but their unfolding pathways are different. A domain compaction and an increase of the ANS fluorescence of holo form have been evidenced. On the contrary, a domain dilatation and an ANS fluorescence decrease have been found for the apo form. The pressure induced an increase of the interdomain distance for both calmodulin forms, suggesting that the central linker of calmodulin is flexible in solution.  相似文献   
943.
Notch receptors are key regulators of nervous system development and promoters of neural stem cells renewal and proliferation. Defects in the expression of Notch genes result in severe, often lethal developmental abnormalities. Notch3 is generally thought to have a similar proliferative, anti‐differentiation and gliogenic role to Notch1. However, in some cases, Notch3 has an opposite, pro‐differentiation effect. Here, we show that Notch3 segregates from Notch1 and is transiently expressed in adult rat and mouse spinal cord neuron precursors and immature neurons. This suggests that during the differentiation of adult neural progenitor cells, Notch signalling may follow a modified version of the classical lateral inhibition model, involving the segregation of individual Notch receptors. Notch3 knockout mice, otherwise neurologically normal, are characterized by a reduced number of mature inhibitory interneurons and an increased number of highly excitable immature neurons in spinal cord laminae I–II. As a result, these mice have permanently lower nociceptive thresholds, similar to chronic pain. These results suggest that defective neuronal differentiation, for example as a result of reduced Notch3 expression or activation, may underlie human cases of intractable chronic pain, such as fibromyalgia and neuropathic pain.  相似文献   
944.
945.
Penalized Multiple Regression (PMR) can be used to discover novel disease associations in GWAS datasets. In practice, proposed PMR methods have not been able to identify well-supported associations in GWAS that are undetectable by standard association tests and thus these methods are not widely applied. Here, we present a combined algorithmic and heuristic framework for PUMA (Penalized Unified Multiple-locus Association) analysis that solves the problems of previously proposed methods including computational speed, poor performance on genome-scale simulated data, and identification of too many associations for real data to be biologically plausible. The framework includes a new minorize-maximization (MM) algorithm for generalized linear models (GLM) combined with heuristic model selection and testing methods for identification of robust associations. The PUMA framework implements the penalized maximum likelihood penalties previously proposed for GWAS analysis (i.e. Lasso, Adaptive Lasso, NEG, MCP), as well as a penalty that has not been previously applied to GWAS (i.e. LOG). Using simulations that closely mirror real GWAS data, we show that our framework has high performance and reliably increases power to detect weak associations, while existing PMR methods can perform worse than single marker testing in overall performance. To demonstrate the empirical value of PUMA, we analyzed GWAS data for type 1 diabetes, Crohns''s disease, and rheumatoid arthritis, three autoimmune diseases from the original Wellcome Trust Case Control Consortium. Our analysis replicates known associations for these diseases and we discover novel etiologically relevant susceptibility loci that are invisible to standard single marker tests, including six novel associations implicating genes involved in pancreatic function, insulin pathways and immune-cell function in type 1 diabetes; three novel associations implicating genes in pro- and anti-inflammatory pathways in Crohn''s disease; and one novel association implicating a gene involved in apoptosis pathways in rheumatoid arthritis. We provide software for applying our PUMA analysis framework.  相似文献   
946.
Kinetochores are large multiprotein complexes that connect centromeres to spindle microtubules in all eukaryotes. Among the biochemically distinct kinetochore complexes, the conserved four-protein Mtw1 complex is a central part of the kinetochore in all organisms. Here we present the biochemical reconstitution and characterization of the budding yeast Mtw1 complex. Direct visualization by electron microscopy revealed an elongated bilobed structure with a 25-nm-long axis. The complex can be assembled from two stable heterodimers consisting of Mtw1p-Nnf1p and Dsn1p-Nsl1p, and it interacts directly with the microtubule-binding Ndc80 kinetochore complex via the centromere-proximal Spc24/Spc25 head domain. In addition, we have reconstituted a partial Ctf19 complex and show that it directly associates with the Mtw1 complex in vitro. Ndc80 and Ctf19 complexes do not compete for binding to the Mtw1 complex, suggesting that Mtw1 can bridge the microtubule-binding components of the kinetochore to the inner centromere.  相似文献   
947.

Background

Adrenomedullin (AM) is highly expressed in pancreatic cancer and stimulates pancreatic cancer cells leading to increased tumor growth and metastasis. The current study examines the role of specific AM receptors on tumor and cells resembling the tumor microenvironment (human pancreatic stellate - HPSC, human umbilical vein – HUVEC and mouse lung endothelial cells - MLEC).

Methods and Findings

AM receptors ADMR and CRLR were present in HPSC, HUVEC and MLECs while PDAC cells possessed only ADMR receptors as assessed by RT-PCR and western blotting. All cell lines expressed and secreted AM as indicated by ELISA. The growth of each of the cell lines was stimulated by exogenous AM and inhibited by the antagonist AMA. AM also stimulated in vitro angiogenesis assessed by polygon formation of endothelial cell lines. SiRNA-mediated silencing of ADMR, but not CRLR, reduced basal growth of all cells examined and reduced polygon formation of endothelial cells in vitro. Orthotopic tumors developed with shADMR bearing cancer cells had dramatically reduced primary tumor volume (>90%) and lung and liver metastasis compared to shControl bearing cells. To validate ADMR as a potential therapeutic target, in vivo studies were conducted using neutral nanoliposomes to systemically deliver human siRNA to ADMR to silence human cancer cells and mouse siRNA to ADMR to silence mouse tumor stromal cells. Systemic silencing of both human and mouse ADMR had no obvious adverse effects but strongly reduced tumor development.

Conclusion

ADMR mediates the stimulatory effects of AM on cancer cells and on endothelial and stellate cells within the tumor microenvironment. These data support the further development of ADMR as a useful target treatment of pancreatic cancer.  相似文献   
948.
Under positive osmotic stress, a greater lipid vesicle swells to a critical diameter, when suddenly a transbilayer pore appears and grows to a maximum radius, then decreases and finally disappears. An amount of liquid was leaked out through the pore and the vesicle returns to the initial state and can start another cycle. This is a pulsatory lipid liposome. In this paper, we have considered the problem of such liposomes. We have obtained the condition that a pulsatory liposome to run an a priori settled number of cycles. The length time of each cycle and its activity life was calculated. Also, we have calculated the quantities of solute leaked out through a pore in each cycle. The pulsatory liposome may be regarded as a biotechnological device to dose drugs at fixed intervals time.  相似文献   
949.
950.

The genus Ctenomys includes a high number of taxa, with at least ten species from Patagonia and three recently described species for northeastern Chubut Province (Argentina). Ctenomys sociabilis is a social species of the genus Ctenomys and is currently distributed in the surrounding area of Sierra Cuyin Manzano (Neuquén Province), with a recently extinct population that occurred in Laguna Nahuelquir (Cushamen, Chubut Province). Molecular analyses have placed C. sociabilis at the base of Ctenomys clade, as the sister species to all other Ctenomys. Based on a morphological assessment (qualitative and quantitative) and DNA sequencing, we describe a new species of Ctenomys from Esquel, Chubut Province. Phylogenetic analysis shows the new species to be closely related to C. sociabilis, with evidence of solitary behavior. This new species is the first reported to be closely related phylogenetically to Ctenomys sociabilis at the base of the Ctenomys phylogeny. We provide anatomical comparisons between the new species and other species of Ctenomys from Patagonia, especially C. sociabilis.

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