Multi-compartment poroelastic models of perfused biological soft tissues: implementation in FEniCSx

Soft biological tissues demonstrate strong time-dependent and strain-rate mechanical behavior, arising from their intrinsic visco-elasticity and fluid-solid interactions (especially at sufficiently large time scales). The time-dependent mechanical properties of soft tissues influence their physiological functions and are linked to several pathological processes. Poro-elastic modeling represents a promising approach because it allows the integration of multiscale/multiphysics data to probe biologically relevant phenomena at a smaller scale and embeds the relevant mechanisms at the larger scale. The implementation of multi-phasic flow poro-elastic models however is a complex undertaking, requiring extensive knowledge. The open-source software FEniCSx Project provides a novel tool for the automated solution of partial differential equations by the finite element method. This paper aims to provide the required tools to model the mixed formulation of poro-elasticity, from the theory to the implementation, within FEniCSx. Several benchmark cases are studied. A column under confined compression conditions is compared to the Terzaghi analytical solution, using the L2-norm. An implementation of poro-hyper-elasticity is proposed. A bi-compartment column is compared to previously published results (Cast3m implementation). For all cases, accurate results are obtained in terms of a normalized Root Mean Square Error (RMSE). Furthermore, the FEniCSx computation is found three times faster than the legacy FEniCS one. The benefits of parallel computation are also highlighted.Comment: https://github.com/Th0masLavigne/Dolfinx_Porous_Media.gi

Benign thyroid nodules treatment using Percutaneous Laser Ablation (PLA) and Radiofrequency Ablation (RFA)

Purpose: To evaluate the reduction over time of benign thyroid nodules treated using percutaneous laser ablation (PLA) and radiofrequency ablation (RFA) by the same equipe. Materials and methods: Ninety patients (age 55.6\u2009\ub1\u200914.1 years) underwent ablation for benign thyroid nodule causing compression/aesthetic dissatisfaction from 2011. Fifty-nine (age 55.8\u2009\ub1\u200914.1 years) underwent RFA and 31 (age 55.2\u2009\ub1\u200914.2 years) PLA, ultrasound guided. Technical success, complications, duration of ablation and treatment, energy deployed, volumetric percentage reduction at 1, 6 and 12 months were derived. A regression model for longitudinal measurements was used with random intercept and random slope. Values are expressed as mean\u2009\ub1\u2009standard deviation or N (%). Results: Technical success was always obtained. No major complications occurred. Mean ablation time was 30.1\u2009\ub1\u200913.8 vs. 13.9\u2009\ub1\u20095.9\u2009min (p\u2009<\u2009.0001) and mean energy deployment was 5422.3\u2009\ub1\u20092484.5 J vs. 34 662.7\u2009\ub1\u200915 812.3 J in PLA vs. RFA group. Mean volume reduced from 20.3\u2009\ub1\u200916.4\u2009ml to 13.17\u2009\ub1\u200910.74\u2009ml (42%\u2009\ub1\u200917% reduction) at 1st month, 8.7\u2009\ub1\u20097.4\u2009ml (60%\u2009\ub1\u200915% reduction) at 6th month and 7.1\u2009\ub1\u20097.7\u2009ml (70%%\u2009\ub1\u200916% reduction) at 12th month, in PLA group, and from 32.7\u2009\ub1\u200919.5\u2009ml to 17.2\u2009\ub1\u200912.9\u2009ml (51%\ub115% reduction) at 1st month, 12.8\u2009\ub1\u20099.6\u2009ml (64\u2009\ub1\u200914% reduction) at 6th month and 9.9\u2009\ub1\u20099.2\u2009ml (74%\u2009\ub1\u200914% reduction) at 12th month in RFA group. No difference in time course of the relative volume reduction between the two techniques was found. Conclusions: RFA and PLA are similarly feasible, safe and effective in treating benign thyroid nodules when performed by the same equipe. RFA is faster than PLA but require significantly higher energy

Reductions in mesophyll and guard cell photosynthesis impact on the control of stomatal responses to light and CO2

Transgenic antisense tobacco plants with a range of reductions in sedoheptulose-1,7-bisphosphatase (SBPase) activity were used to investigate the role of photosynthesis in stomatal opening responses. High resolution chlorophyll a fluorescence imaging showed that the quantum efficiency of photosystem II electron transport (Fq′/Fm′) was decreased similarly in both guard and mesophyll cells of the SBPase antisense plants compared to the wild-type plants. This demonstrated for the first time that photosynthetic operating efficiency in the guard cells responds to changes in the regeneration capacity of the Calvin cycle. The rate of stomatal opening in response to a 30 min, 10-fold step increase in red photon flux density in the leaves from the SBPase antisense plants was significantly greater than wild-type plants. Final stomatal conductance under red and mixed blue/red irradiance was greater in the antisense plants than in the wild-type control plants despite lower CO2 assimilation rates and higher internal CO2 concentrations. Increasing CO2 concentration resulted in a similar stomatal closing response in wild-type and antisense plants when measured in red light. However, in the antisense plants with small reductions in SBPase activity greater stomatal conductances were observed at all Ci levels. Together, these data suggest that the primary light-induced opening or CO2-dependent closing response of stomata is not dependent upon guard or mesophyll cell photosynthetic capacity, but that photosynthetic electron transport, or its end-products, regulate the control of stomatal responses to light and CO2. © 2008 The Author(s)

Flavodiiron Proteins in Oxygenic Photosynthetic Organisms: Photoprotection of Photosystem II by Flv2 and Flv4 in Synechocystis sp. PCC 6803

BACKGROUND: Flavodiiron proteins (FDPs) comprise a group of modular enzymes that function in oxygen and nitric oxide detoxification in Bacteria and Archaea. The FDPs in cyanobacteria have an extra domain as compared to major prokaryotic enzymes. The physiological role of cyanobacteria FDPs is mostly unknown. Of the four putative flavodiiron proteins (Flv1-4) in the cyanobacterium Synechocystis sp. PCC 6803, a physiological function in Mehler reaction has been suggested for Flv1 and Flv3. PRINCIPAL FINDINGS: We demonstrate a novel and crucial function for Flv2 and Flv4 in photoprotection of photosystem II (PSII) in Synechocystis. It is shown that the expression of Flv2 and Flv4 is high under air level of CO(2) and negligible at elevated CO(2). Moreover, the rate of accumulation of flv2 and flv4 transcripts upon shift of cells from high to low CO(2) is strongly dependent on light intensity. Characterization of FDP inactivation mutants of Synechocystis revealed a specific decline in PSII centers and impaired translation of the D1 protein in Delta flv2 and Delta flv4 when grown at air level CO(2) whereas at high CO(2) the Flvs were dispensable. Delta flv2 and Delta flv4 were also more susceptible to high light induced inhibition of PSII than WT or Delta flv1 and Delta flv3. SIGNIFICANCE: Analysis of published sequences revealed the presence of cyanobacteria-like FDPs also in some oxygenic photosynthetic eukaryotes like green algae, mosses and lycophytes. Our data provide evidence that Flv2 and Flv4 have an important role in photoprotection of water-splitting PSII against oxidative stress when the cells are acclimated to air level CO(2). It is conceivable that the function of FDPs has changed during evolution from protection against oxygen in anaerobic microbes to protection against reactive oxygen species thus making the sustainable function of oxygen evolving PSII possible. Higher plants lack FDPs and distinctly different mechanisms have evolved for photoprotection of PSII

Microneedles: A New Frontier in Nanomedicine Delivery

This review aims to concisely chart the development of two individual research fields, namely nanomedicines, with specific emphasis on nanoparticles (NP) and microparticles (MP), and microneedle (MN) technologies, which have, in the recent past, been exploited in combinatorial approaches for the efficient delivery of a variety of medicinal agents across the skin. This is an emerging and exciting area of pharmaceutical sciences research within the remit of transdermal drug delivery and as such will undoubtedly continue to grow with the emergence of new formulation and fabrication methodologies for particles and MN. Firstly, the fundamental aspects of skin architecture and structure are outlined, with particular reference to their influence on NP and MP penetration. Following on from this, a variety of different particles are described, as are the diverse range of MN modalities currently under development. The review concludes by highlighting some of the novel delivery systems which have been described in the literature exploiting these two approaches and directs the reader towards emerging uses for nanomedicines in combination with MN