Le pouvoir stupéfiant de la lecture !

Entretien avec Charles Prémont, ethnologue de formation, journaliste et auteur, qui s’intéresse à l’importance de la lecture au Québec depuis plusieurs années. Propos recueillis par Julie Roberge, membre du comité de rédaction

Progress in developing a living human tissue-engineered tri-leaflet heart valve assembled from tissue produced by the self-assembly approach

The aortic heart valve is constantly subjected to pulsatile flow and pressure gradients which, associated with cardiovascular risk factors and abnormal hemodynamics (i.e. altered wall shear stress), can cause stenosis and calcification of the leaflets and result in valve malfunction and impaired circulation. Avail- able options for valve replacement include homograft, allogenic or xenogenic graft as well as the implan- tation of a mechanical valve. A tissue-engineered heart valve containing living autologous cells would represent an alternative option, particularly for pediatric patients, but still needs to be developed. The present study was designed to demonstrate the feasibility of using a living tissue sheet produced by the self-assembly method, to replace the bovine pericardium currently used for the reconstruction of a stented human heart valve. In this study, human fibroblasts were cultured in the presence of sodium ascorbate to produce tissue sheets. These sheets were superimposed to create a thick construct. Tissue pieces were cut from these constructs and assembled together on a stent, based on techniques used for commercially available replacement valves. Histology and transmission electron microscopy analysis showed that the fibroblasts were embedded in a dense extracellular matrix produced in vitro. The mechanical properties measured were consistent with the fact that the engineered tissue was resistant and could be cut, sutured and assembled on a wire frame typically used in bioprosthetic valve assembly. After a culture period in vitro, the construct was cohesive and did not disrupt or disassemble. The tissue engineered heart valve was stimulated in a pulsatile flow bioreactor and was able to sustain multiple duty cycles. This prototype of a tissue-engineered heart valve containing cells embedded in their own extracellular matrix and sewn on a wire frame has the potential to be strong enough to support physio- logical stress. The next step will be to test this valve extensively in a bioreactor and at a later date, in a large animal model in order to assess in vivo patency of the graft

Incidence and Severity of Lymphoedema following Limb Salvage of Extremity Soft Tissue Sarcoma

Background and Purpose. Lymphoedema is a serious complication following limb salvage for extremity soft tissue sarcomas (STSs) for which little is known. We aimed to evaluate its incidence, its, severity and its associated risk factors. Material and Method. Patient and tumor characteristics, treatment modalities and complications and functional outcomes (MSTS 1987, TESS), and lymphoedema severity (Stern) were all collected from prospective databases. Charts were retrospectively abstracted for BMI and comorbidities. Results. There were 289 patients (158 males). Mean age was 53 (16–88). Followup ranged between 12 and 60 months with an average of 35 and a median of 36 months. Mean BMI was 27.4 (15.8–52.1). 72% had lower extremity tumors and 38% upper extremity. Mean tumor size was 8.1 cm (1.0–35.6 cm). 27% had no adjuvant radiation, 62% had 50 Gy, and 11% received 66 Gy. The incidence of lymphoedema was 28.8% (206 none, 58 mild, 22 moderate, 3 severe, and 0 very severe). Mean MSTS score was 32 (11–35) and TESS was 89.4 (32.4–100). Radiation dose was significantly correlated with tumor size > 5 cm (P = 0.0001) and TESS score (P = 0.001), but not MSTS score (P = 0.090). Only tumor size > 5 cm and depth were found to be independent predictors of significant lymphoedema. Conclusion. Nine percent of STS patients in our cohort developed significant (grade ≥ 2) lymphoedema. Tumor size > 5 cm and deep tumors were associated with an increased occurrence of lymphoedema but not radiation dosage

F.A.R.O.G. FORUM, Vol. 2 No. 5

https://digitalcommons.library.umaine.edu/francoamericain_forum/1005/thumbnail.jp

Electric potential across epidermis and its role during wound healing can be studied by using an in vitro reconstructed human skin

Background : After human epidermis wounding, transepithelial potential (TEP) present in nonlesional epidermis decreases and induces an endogenous direct current epithelial electric field (EEF) that could be implicated in the wound re-epithelialization. Some studies suggest that exogenous electric stimulation of wounds can stimulate healing, although the mechanisms remain to be determined. The Problem : Little is known concerning the exact action of the EEF during healing. The mechanism responsible for TEP and EEF is unknown due to the lack of an in vitro model to study this phenomenon. Basic Science Advances : We carried out studies by using a wound created in a human tissue-engineered skin and determined that TEP undergoes ascending and decreasing phases during the epithelium formation. The in vitro TEP measurements over time in the wound were corroborated with histological changes and with in vivo TEP variations during porcine skin wound healing. The expression of a crucial element implicated in Na+ transport, Na+/K+ ATPase pumps, was also evaluated at the same time points during the re-epithelialization process. The ascending and decreasing TEP values were correlated with changes in the expression of these pumps. The distribution of Na+/K+ ATPase pumps also varied according to epidermal differentiation. Further, inhibition of the pump activity induced a significant decrease of the TEP and of the re-epithelization rate. Clinical Care Relevance : A better comprehension of the role of EEF could have important future medical applications regarding the treatment of chronic wound healing. Conclusion : This study brings a new perspective to understand the formation and restoration of TEP during the cutaneous wound healing process

Imaging Cool Giant Planets in Reflected Light: Science Investigations and Synergy with Habitable Planets

Planned astronomical observatories of the 2020s will be capable of obtaining reflected light photometry and spectroscopy of cool extrasolar giant planets. Here we explain that such data are valuable both for understanding the origin and evolution of giant planets as a whole and for preparing for the interpretation of similar datasets from potentially habitable extrasolar terrestrial planets in the decades to follow.Comment: Science white paper submitted to the Astro 2020 Decadal Survey on Astronomy and Astrophysics. Replace version to fix typo in co-signer name and add figure credit

Le Forum, Vol. 40 No. 3

https://digitalcommons.library.umaine.edu/francoamericain_forum/1088/thumbnail.jp

HD 172555: Detection of 63 μ m [OI] emission in a debris disc

Astronomy and Astrophysics 546 (2012): L8 Reproduced with permission from Astronomy & AstrophysicsContext. HD 172555 is a young A7 star belonging to the β Pictoris moving group that harbours a debris disc. The Spitzer/IRS spectrum of the source showed mid-IR features such as silicates and glassy silica species, indicating the presence of a warm dust component with small grains, which places HD 172555 among the small group of debris discs with such properties. The IRS spectrum also shows a possible emission of SiO gas. Aims. We aim to study the dust distribution in the circumstellar disc of HD 172555 and to asses the presence of gas in the debris disc. Methods. As part of the GASPS open time key programme, we obtained Herschel/PACS photometric and spectroscopic observations of the source.We analysed PACS observations of HD 172555 and modelled the spectral energy distribution with a modified blackbody and the gas emission with a two-level population model with no collisional de-excitation. Results. We report for the first time the detection of [OI] atomic gas emission at 63.18 μm in the HD 172555 circumstellar disc. We detect excesses due to circumstellar dust toward HD 172555 in the three photometric bands of PACS (70, 100, and 160 μm).We derive a large dust particle mass of (4.8 ± 0.6) × 10−4 M⊕ and an atomic oxygen mass of 2.5 × 10−2R2 M⊕, where R in AU is the separation between the star and the inner disc. Thus, most of the detected mass of the disc is in the gaseous phaseThis research has been funded by Spanish grants AYA 2010-21161-C02-02, CDS2006-00070 and PRICIT-S2009/ESP-1496. J.-C. Augereau and J. Lebreton thank the ANR (contract ANR-2010 BLAN-0505-01, EXOZODI) and the CNES-PNP for financial support. C. Pinte, F. Menard and W.-F. Thi acknowledges funding from the EU FP7-2011 under Grant Agreement nr. 284405. G. Meeus is supported by RYC-2011-07920. G. Meeus, C. Eiroa, I. Mendigutía and B. Montesinos are partly supported by AYA-2011-26202. F.M. acknowledges support from the Millennium Science Initiative (Chilean Ministry of Economy), through grant ÒNucleus P10-022-F