588 research outputs found
Early transverse tubule development begins in utero in the sheep heart.
Published onlineJournal ArticleThis is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.The ventricular cardiomyocytes of adult mammals contain invaginations of the plasma membrane known as transverse (t)-tubules. These regular structures are essential for the synchronisation of excitation-contraction (EC) coupling throughout the cell, which is a vital process for cardiac function. T-tubules form a close association with the sarcoplasmic reticulum (SR) to form junctions, where several key proteins involved in EC coupling are localised, including the SR calcium release channels-the ryanodine receptors (RyR). The lipophilic SR protein junctophilin-2 (JPH2) has been implicated in the development of both the junctions and t-tubules. Several studies have identified that t-tubules develop only postnatally in rodents, while historical electron microscopy data indicate that this is not the case in larger mammals, including humans. We have performed, to our knowledge, the first fluorescent, target-specific study to characterise t-tubule development in the large mammalian fetal heart, focussing on the sheep. T-tubules were present in fetal sheep hearts from 114Â days gestation (with term being 145Â days), with occurrence progressively increasing with gestational age, and further maturation after birth. This was accompanied by an increasing intracellular localisation of JPH2, which progressively increased its association with RyR within the cardiomyocytes as they undergo hypertrophy. These findings indicate that large mammalian hearts exhibit a significantly different temporal pattern of development compared to that of the rodent. Our findings have potential implications for human cardiac development, including the future investigation of congenital heart disease.This research was supported by a Health Research Council of New Zealand grant (#12/240) awarded to CS. We wish to thank Prof Laura Bennet, Dr Joanne Davidson and the Fetal Physiology & Neuroscience group, Department of Physiology, University of Auckland for supplying the tissue used in this study, with original projects supported by Health Research Council of New Zealand research grants (#14/216 and #12/613)
Mechanisms underlying calcium sparks in cardiac muscle
This is the final version. Available from Rockefeller University Press via the DOI in this record
Wide field fluorescence epi-microscopy behind a scattering medium enabled by speckle correlations
Fluorescence microscopy is widely used in biological imaging, however
scattering from tissues strongly limits its applicability to a shallow depth.
In this work we adapt a methodology inspired from stellar speckle
interferometry, and exploit the optical memory effect to enable fluorescence
microscopy through a turbid layer. We demonstrate efficient reconstruction of
micrometer-size fluorescent objects behind a scattering medium in
epi-microscopy, and study the specificities of this imaging modality
(magnification, field of view, resolution) as compared to traditional
microscopy. Using a modified phase retrieval algorithm to reconstruct
fluorescent objects from speckle images, we demonstrate robust reconstructions
even in relatively low signal to noise conditions. This modality is
particularly appropriate for imaging in biological media, which are known to
exhibit relatively large optical memory ranges compatible with tens of
micrometers size field of views, and large spectral bandwidths compatible with
emission fluorescence spectra of tens of nanometers widths
Quaternary and environmental geology of Lemmon Valley, Nevada
Online access for this thesis was created in part with support from the Institute of Museum and Library Services (IMLS) administered by the Nevada State Library, Archives and Public Records through the Library Services and Technology Act (LSTA). To obtain a high quality image or document please contact the DeLaMare Library at https://unr.libanswers.com/ or call: 775-784-6945.Over 1000 vertical feet of loose to weakly consolidated Tertiary and Quaternary sediments occupy the closed Lemmon Valley basin. Mountains comprising Mesozoic granitic and metavolcanic rocks border the valley. Fourteen Quaternary geologic units within the forty-eight-square-mile field area include pediment gravels, six varieties of alluvium, beach, forebeach, lake, landslide and playa deposits, windblown sand and playa-bordering clay dunes. North-south and northeast-southwest trending normal faults cut early Pleistocene deposits and delineate subordinate horsts and grabens within the basin. The prominent Airport fault offsets Tertiary and early Quaternary sediments 120 feet and granitic bedrock over 600 feet vertically. Hazards to valley inhabitants include flooding, faulting, seismic shaking, landsliding, and expansive soils. Losses of construction aggregate resources and overdrafting of domestic ground water supplies may occur through over-population of the valley as demands for more housing are made by the neighboring Reno-Sparks community
Investigation of the Hydromechanical Effects of Lithostatic Unloading in Open-pit Mines
Thesis advisor: Alan KafkaThe stability of open-pit mine walls and other geotechnical infrastructure is a function of geometry, material properties and groundwater conditions (pore pressure distribution). A portion of failures are attributed to the effect of pore water pressures within the mine wall slopes. The objective of this research was to investigate the interaction between the increments/decrements of stresses that occur during the lithostatic unloading/excavation of the pit and the increments/decrements of pore water pressures. This interaction can be described by the theory of linear poroelasticity, which incorporates the coupling between changes in fluid pressure and changes in stress in porous media. The results of this thesis are displayed in the form of contour charts and graphs.Thesis (MS) — Boston College, 2016.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: Earth and Environmental Sciences
Cardiac multiscale bioimaging: from nano- through micro- to mesoscales.
Cardiac multiscale bioimaging is an emerging field that aims to provide a comprehensive understanding of the heart and its functions at various levels, from the molecular to the entire organ. It combines both physiologically and clinically relevant dimensions: from nano- and micrometer resolution imaging based on vibrational spectroscopy and high-resolution microscopy to assess molecular processes in cardiac cells and myocardial tissue, to mesoscale structural investigations to improve the understanding of cardiac (patho)physiology. Tailored super-resolution deep microscopy with advanced proteomic methods and hands-on experience are thus strategically combined to improve the quality of cardiovascular research and support future medical decision-making by gaining additional biomolecular information for translational and diagnostic applications
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