Overexpression of connexin 43 using a retroviral vector improves electrical coupling of skeletal myoblasts with cardiac myocytes in vitro.

BACKGROUND: Organ transplantation is presently often the only available option to repair a damaged heart. As heart donors are scarce, engineering of cardiac grafts from autologous skeletal myoblasts is a promising novel therapeutic strategy. The functionality of skeletal muscle cells in the heart milieu is, however, limited because of their inability to integrate electrically and mechanically into the myocardium. Therefore, in pursuit of improved cardiac integration of skeletal muscle grafts we sought to modify primary skeletal myoblasts by overexpression of the main gap-junctional protein connexin 43 and to study electrical coupling of connexin 43 overexpressing myoblasts to cardiac myocytes in vitro. METHODS: To create an efficient means for overexpression of connexin 43 in skeletal myoblasts we constructed a bicistronic retroviral vector MLV-CX43-EGFP expressing the human connexin 43 cDNA and the marker EGFP gene. This vector was employed to transduce primary rat skeletal myoblasts in optimised conditions involving a concomitant use of the retrovirus immobilising protein RetroNectin and the polycation transduction enhancer Transfectam. The EGFP-positive transduced cells were then enriched by flow cytometry. RESULTS: More than four-fold overexpression of connexin 43 in the transduced skeletal myoblasts, compared with non-transduced cells, was shown by Western blotting. Functionality of the overexpressed connexin 43 was demonstrated by microinjection of a fluorescent dye showing enhanced gap-junctional intercellular transfer in connexin 43 transduced myoblasts compared with transfer in non-transduced myoblasts. Rat cardiac myocytes were cultured in multielectrode array culture dishes together with connexin 43/EGFP transduced skeletal myoblasts, control non-transduced skeletal myoblasts or alone. Extracellular field action potential activation rates in the co-cultures of connexin 43 transduced skeletal myoblasts with cardiac myocytes were significantly higher than in the co-cultures of non-transduced skeletal myoblasts with cardiac myocytes and similar to the rates in pure cultures of cardiac myocytes. CONCLUSION: The observed elevated field action potential activation rate in the co-cultures of cardiac myocytes with connexin 43 transduced skeletal myoblasts indicates enhanced cell-to-cell electrical coupling due to overexpression of connexin 43 in skeletal myoblasts. This study suggests that retroviral connexin 43 transduction can be employed to augment engineering of the electrocompetent cardiac grafts from patients own skeletal myoblasts

QKD in Standard Optical Telecommunications Networks

To perform Quantum Key Distribution, the mastering of the extremely weak signals carried by the quantum channel is required. Transporting these signals without disturbance is customarily done by isolating the quantum channel from any noise sources using a dedicated physical channel. However, to really profit from this technology, a full integration with conventional network technologies would be highly desirable. Trying to use single photon signals with others that carry an average power many orders of magnitude bigger while sharing as much infrastructure with a conventional network as possible brings obvious problems. The purpose of the present paper is to report our efforts in researching the limits of the integration of QKD in modern optical networks scenarios. We have built a full metropolitan area network testbed comprising a backbone and an access network. The emphasis is put in using as much as possible the same industrial grade technology that is actually used in already installed networks, in order to understand the throughput, limits and cost of deploying QKD in a real network

Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements

A three-component reflectance model (3C) is applied to above-water radiometric measurements to derive remote-sensing reflectance Rrs (λ). 3C provides a spectrally resolved offset Δ(λ) to correct for residual sun and sky radiance (Rayleigh- and aerosol-scattered) reflections on the water surface that were not represented by sky radiance measurements. 3C is validated with a data set of matching above- and below-water radiometric measurements collected in the Baltic Sea, and compared against a scalar offset correction Δ. Correction with Δ(λ) instead of Δ consistently reduced the (mean normalized root-mean-square) deviation between Rrs (λ) and reference reflectances to comparable levels for clear (Δ: 14.3 ± 2.5 %, Δ(λ): 8.2 ± 1.7 %), partly clouded (Δ: 15.4 ± 2.1 %, Δ(λ): 6.5 ± 1.4 %), and completely overcast (Δ: 10.8 ± 1.7 %, Δ(λ): 6.3 ± 1.8 %) sky conditions. The improvement was most pronounced under inhomogeneous sky conditions when measurements of sky radiance tend to be less representative of surface-reflected radiance. Accounting for both sun glint and sky reflections also relaxes constraints on measurement geometry, which was demonstrated based on a semi-continuous daytime data set recorded in a eutrophic freshwater lake in the Netherlands. Rrs (λ) that were derived throughout the day varied spectrally by less than 2 % relative standard deviation. Implications on measurement protocols are discussed. An open source software library for processing reflectance measurements was developed and is made publicly available

Variability of adjacency effects in sky reflectance measurements

Sky reflectance Rsky(l) is used to correct in situ reflectance measurements in the remote detection of water colour. We analysed the directional and spectral variability in Rsky(l) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous Rsky(l) observations that were recorded in two azimuth directions. Adjacency effects contributed to Rsky(l) dependent on season and viewing angle, and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. Reflectance differed between viewing directions 5.4 +/- 6.3% for adjacency effects and 21.0 +/- 19.8% for Rayleigh- and aerosol-scattered Rsky(l), in the NIR. It is discussed under which conditions in situ water reflectance observations require dedicated correction for adjacency effects. We provide an open source implementation of our method to aid identification of such conditions. Copyright 2017 Optical Society of America

Plum pudding random medium model of biological tissue toward remote microscopy from spectroscopic light scattering

Biological tissue has a complex structure and exhibits rich spectroscopic behavior. There is \emph{no} tissue model up to now able to account for the observed spectroscopy of tissue light scattering and its anisotropy. Here we present, \emph{for the first time}, a plum pudding random medium (PPRM) model for biological tissue which succinctly describes tissue as a superposition of distinctive scattering structures (plum) embedded inside a fractal continuous medium of background refractive index fluctuation (pudding). PPRM faithfully reproduces the wavelength dependence of tissue light scattering and attributes the "anomalous" trend in the anisotropy to the plum and the powerlaw dependence of the reduced scattering coefficient to the fractal scattering pudding. Most importantly, PPRM opens up a novel venue of quantifying the tissue architecture and microscopic structures on average from macroscopic probing of the bulk with scattered light alone without tissue excision. We demonstrate this potential by visualizing the fine microscopic structural alterations in breast tissue (adipose, glandular, fibrocystic, fibroadenoma, and ductal carcinoma) deduced from noncontact spectroscopic measurement

Older adults who have previously fallen due to a trip walk differently than those who have fallen due to a slip

Studying the relationships between centre of mass (COM) and centre of pressure (COP) during walking has been shown to be useful in determining movement stability. The aim of the current study was to compare COM–COP separation measures during walking between groups of older adults with no history of falling, and a history of falling due to tripping or slipping. Any differences between individuals who have fallen due to a slip and those who have fallen due to a trip in measures of dynamic balance could potentially indicate differences in the mechanisms responsible for falls. Forty older adults were allocated into groups based on their self-reported fall history during walking. The non-faller group had not experienced a fall in at least the previous year. Participants who had experienced a fall were split into two groups based on whether a trip or slip resulted in the fall(s). A Vicon system was used to collect full body kinematic trajectories. Two force platforms were used to measure ground reaction forces. The COM was significantly further ahead of the COP at heel strike for the trip (14.3 ± 2.7 cm) and slip (15.3 ± 1.1 cm) groups compared to the non-fallers (12.0 ± 2.7 cm). COM was significantly further behind the COP at foot flat for the slip group (−14.9 ± 3.6 cm) compared to the non-fallers (−10.3 ± 3.9 cm). At mid-swing, the COM of the trip group was ahead of the COP (0.9 ± 1.6 cm), whereas for the slip group the COM was behind the COP (−1.2 ± 2.2 cm). These results show identifiable differences in dynamic balance control of walking between older adults with a history of tripping or slipping and non-fallers

Concomitant Crystallization in Propylene/Ethylene Random Copolymer with Strong Flow at Elevated Temperatures

Flow-induced crystallization of α- and γ-phases was studied for a propylene/ethylene random copolymer with 3.4 mol % ethylene at two high temperatures of 132 and 142 °C by combining a pressure-driven slit flow device with real-time synchrotron wide-angle X-ray diffraction. At 132 °C, it was found that both α- and γ-phases were generated at shear stresses ranging from 0.091 to 0.110 MPa and that the γ-phase always appeared later than the α-phase. However, for 142 °C and the same stresses, only the α-phase formed. Only upon cooling the partially crystallized copolymer did the γ-phase emerge. The lack of γ-crystals obtained at 142 °C is opposite to the behavior reported for quiescent crystallization under pressure, for which increasing temperature results in more and even pure γ-crystals. In the current study, the absence of γ-phase at 142 °C is tentatively associated with lack of epitaxial nucleation on α-lamellae and to relatively low growth rate of γ-crystals