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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 13 (1998), S. 3-13 
    ISSN: 1435-604X
    Keywords: Biopsy ; Fluorescence ; Optical ; Raman ; Spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The early diagnosis of gastrointestinal malignancy will allow eradication of the disease prior to invasive cancer. At present, fluorescence spectroscopy offers the most realistic prospect of an early clinical system and is currently under evaluation. Optical coherence tomography can differentiate the layers of the oesophageal wall and has greater reolution than ultrasound. Although complicated, Raman spectroscopy offers the greatest information with possible development of a molecular endoscope.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2016-04-22
    Description: Methods for measuring genetic distances in phylogenetics are known to be sensitive to the evolutionary model assumed. However, there is a lack of established methodology to accommodate the trade-off between incorporating sufficient biological reality and avoiding model overfitting. In addition, as traditional methods measure distances based on the observed number of substitutions, their tend to underestimate distances between diverged sequences due to backward and parallel substitutions. Various techniques were proposed to correct this, but they lack the robustness against sequences that are distantly related and of unequal base frequencies. In this article, we present a novel genetic distance estimate based on information theory that overcomes the above two hurdles. Instead of examining the observed number of substitutions, this method estimates genetic distances using Shannon’s mutual information. This naturally provides an effective framework for balancing model complexity and goodness of fit. Our distance estimate is shown to be approximately linear to elapsed time and hence is less sensitive to the divergence of sequence data and compositional biased sequences. Using extensive simulation data, we show that our method 1) consistently reconstructs more accurate phylogeny topologies than existing methods, 2) is robust in extreme conditions such as diverged phylogenies, unequal base frequencies data, and heterogeneous mutation patterns, and 3) scales well with large phylogenies.
    Print ISSN: 0737-4038
    Electronic ISSN: 1537-1719
    Topics: Biology
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  • 3
    Publication Date: 2020-10-29
    Description: Capitellid polychaetes are ubiquitous throughout the world’s oceans and are often encountered in high abundance. We used an extensive dataset of species abundance and distribution records of the Capitella capitata complex, C. aciculata, C. jonesi, Heteromastus filiformis, Mediomastus ambiseta, and M. californiensis from Tampa Bay, Florida, USA, as a model system of closely related species filling a similar ecological niche. We sought to (1) characterize the spatial distribution of each species, (2) determine if a single species abundance modeling strategy could be applied to them all, and (3) assess environmental drivers of species distribution and abundance. We found that all species had a zero-inflated abundance distribution and there was spatial autocorrelation by bay regions. Lorenz curves were an effective tool to assess spatial patterns of species abundance across large areas. Bay segment, depth, and dissolved oxygen were the most important environmental drivers. Modeling was accomplished by comparing 6 different approaches: 4 generalized additive models (GAMs: Poisson, negative binomial, Tweedie, and zero-inflated Poisson distributions), hurdle models, and boosted regression trees. There was no single model with top performance for every species. However, GAM-Tweedie and hurdle models performed well overall and may be useful for studies of other benthic marine invertebrates.
    Print ISSN: 0171-8630
    Electronic ISSN: 1616-1599
    Topics: Biology
    Published by Inter-Research
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  • 4
    Publication Date: 2019-07-13
    Description: Transforming growth factor beta 1 (TGF beta) is a multifunctional cytokine that orchestrates response to injury via ubiquitous cell surface receptors. The biological activity of TGF beta is restrained by its secretion as a latent complex (LTGF beta) such that activation determines the extent of TGF beta activity during physiological and pathological events. TGF beta action has been implicated in a variety of reactive oxygen-mediated tissue processes, particularly inflammation, and in pathologies such as reperfusion injury, rheumatoid arthritis, and atherosclerosis. It was recently shown to be rapidly activated after in vivo radiation exposure, which also generates reactive oxygen species (ROS). In the present studies, the potential for redox-mediated LTGF beta activation was investigated using a cell-free system in which ROS were generated in solution by ionizing radiation or metal ion-catalyzed ascorbate reaction. Irradiation (100 Gray) of recombinant human LTGF beta in solution induced 26% activation compared with that elicited by standard thermal activation. Metal-catalyzed ascorbate oxidation elicited extremely efficient recombinant LTGF beta activation that matched or exceeded thermal activation. The efficiency of ascorbate activation depended on ascorbate concentrations and the presence of transition metal ions. We postulate that oxidation of specific amino acids in the latency-conferring peptide leads to a conformation change in the latent complex that allows release of TGF beta. Oxidative activation offers a novel route for the involvement of TGF beta in tissue processes in which ROS are implicated and endows LTGF beta with the ability to act as a sensor of oxidative stress and, by releasing TGF beta, to function as a signal for orchestrating the response of multiple cell types. LTGF beta redox sensitivity is presumably directed toward recovery of homeostasis; however, oxidation may also be a mechanism of LTGF beta activation that can be deleterious during disease mechanisms involving chronic ROS production.
    Keywords: Life Sciences (General)
    Type: Molecular endocrinology (Baltimore, Md.) (ISSN 0888-8809); 10; 9; 1077-83
    Format: text
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