Osmotic response during kidney perfusion with cryoprotectant in isotonic or hypotonic vehicle solution
PeerJ » Biophysics
by Ross M. Warner, Jun Yang, Andrew Drake, Youngjoo Lee, Sarah Nemanic, David Scott, Adam Z. Higgins
1w ago
Organ cryopreservation would revolutionize transplantation by overcoming the shelf-life limitations of conventional organ storage. To prepare an organ for cryopreservation, it is first perfused with cryoprotectants (CPAs). These chemicals can enable vitrification during cooling, preventing ice damage. However, CPAs can also cause toxicity and osmotic damage. It is a major challenge to find the optimal balance between protecting the cells from ice and avoiding CPA-induced damage. In this study, we examined the organ perfusion process to shed light on phenomena relevant to cryopreservation proto ..read more
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Rational synthesis of total damage during cryoprotectant equilibration: modelling and experimental validation of osmomechanical, temperature, and cytotoxic damage in sea urchin (Paracentrotus lividus) oocytes
PeerJ » Biophysics
by Dominic J. Olver, Pablo Heres, Estefania Paredes, James D. Benson
3M ago
Sea urchins (e.g., Paracentrotus lividus) are important for both aquaculture and as model species. Despite their importance, biobanking of urchin oocytes by cryopreservation is currently not possible. Optimized cryoprotectant loading may enable novel vitrification methods and thus successful cryopreservation of oocytes. One method for determining an optimized loading protocol uses membrane characteristics and models of damage, namely osmomechanical damage, temperature damage (e.g., chill injury) and cytotoxicity. Here we present and experimentally evaluate existing and novel models of these da ..read more
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Comparison of the elastic recovery and strain-in-compression of commercial and novel vinyl polysiloxane impression materials incorporating a novel crosslinking agent and a surfactant
PeerJ » Biophysics
by Shahab Ud Din, Osama Khattak, Farooq Ahmad Chaudhary, Asfia Saeed, Azhar Iqbal, Jamaluddin Syed, Alaa Ahmed Kensara, Thani Alsharari, Mohammed Mustafa, Sherif Elsayed Sultan, Mangala Patel
4M ago
This study aims to formulate experimental vinylpolysiloxane (VPS) impression materials and compare their elastic recovery and strain-in-compressions with three commercial VPS materials (Aquasil, Elite, and Extrude). Five experimental materials (Exp), two hydrophobic (Exp-I and II) and three hydrophilic (Exp-III, IV and V) were developed. Exp 1 contained vinyl-terminated poly-dimethyl siloxane and a conventional cross-linking agent (poly methylhydrosiloxane), while Exp- II contained a novel cross-linking agent that is tetra-functional dimethyl-silyl-ortho-silicate (TFDMSOS). Exp III–V (hydrophi ..read more
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Micro-shear bond strength of different calcium silicate materials to bulk-fill composite
PeerJ » Biophysics
by Seda Falakaloğlu, Merve Yeniçeri Özata, Gianluca Plotino
8M ago
Introduction This study aimed to compare the micro-shear bond strength (µSBS) performances of two resin-based calcium silicate-based cement (CSC) (TheraCal PT and TheraCal LC), Biodentine, and two modified-MTA CSC materials (NeoMTA 2 and BioMTA+) to bulk-fill restorative material. Materials and Methods Fifty 3D printed cylindrical resin blocks with a central hole were used (2 mm in depth and 4 mm in diameter). CSCs were placed in the holes (per each group n = 10) and incubated for 24 h. Cylindrical polyethylene molds (2 mm in height and diameter) were used to place the bulk-fill restorative ma ..read more
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Acute ventilatory responses to swimming at increasing intensities
PeerJ » Biophysics
by Ana Sofia Monteiro, José Francisco Magalhães, Beat Knechtle, Cosme F. Buzzachera, J. Paulo Vilas-Boas, Ricardo J. Fernandes
9M ago
Background Physical exercise is a source of stress to the human body, triggering different ventilatory responses through different regulatory mechanisms and the aquatic environment imposes several restrictions to the swimmer, particularly regarding the restricted ventilation. Thus, we aimed to assess the acute ventilatory responses and to characterize the adopted breathing patterns when swimming front crawl at increasing intensity domains. Methods Eighteen well-trained swimmers performed 7 × 200 m front crawl (0.05 m∙s−1 velocity increments) and a maximal 100 m (30 s rest intervals). Pulmonary ..read more
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Musculoskeletal simulations to examine the effects of accentuated eccentric loading (AEL) on jump height
PeerJ » Biophysics
by Eric Yung-Sheng Su, Timothy J. Carroll, Dominic J. Farris, Glen A. Lichtwark
11M ago
Background During counter movement jumps, adding weight in the eccentric phase and then suddenly releasing this weight during the concentric phase, known as accentuated eccentric loading (AEL), has been suggested to immediately improve jumping performance. The level of evidence for the positive effects of AEL remains weak, with conflicting evidence over the effectiveness in enhancing performance. Therefore, we proposed to theoretically explore the influence of implementing AEL during constrained vertical jumping using computer modelling and simulation and examined whether the proposed mechanis ..read more
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The energetic effect of hip flexion and retraction in walking at different speeds: a modeling study
PeerJ » Biophysics
by Jian Jin, Dinant Kistemaker, Jaap H. van Dieën, Andreas Daffertshofer, Sjoerd M. Bruijn
11M ago
In human walking, power for propulsion is generated primarily via ankle and hip muscles. The addition of a ‘passive’ hip spring to simple bipedal models appears more efficient than using only push-off impulse, at least, when hip spring associated energetic costs are not considered. Hip flexion and retraction torques, however, are not ‘free’, as they are produced by muscles demanding metabolic energy. Studies evaluating the inclusion of hip actuation costs, especially during the swing phase, and the hip actuation’s energetic benefits are few and far between. It is also unknown whether these pos ..read more
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Rapid restructurization of conformationally-distinct alpha-synuclein amyloid fibrils at an elevated temperature
PeerJ » Biophysics
by Mantas Ziaunys, Andrius Sakalauskas, Kamile Mikalauskaite, Vytautas Smirnovas
1y ago
Protein aggregation in the form of amyloid fibrils is linked with the onset and progression of more than 30 amyloidoses, including multiple neurodegenerative disorders, such as Alzheimer’s or Parkinson’s disease. Despite countless studies and years of research, the process of such aggregate formation is still not fully understood. One peculiar aspect of amyloids is that they appear to be capable of undergoing structural rearrangements even after the fibrils have already formed. Such a phenomenon was reported to occur in the case of alpha-synuclein and amyloid beta aggregates after a long perio ..read more
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Estimating bite force in extinct dinosaurs using phylogenetically predicted physiological cross-sectional areas of jaw adductor muscles
PeerJ » Biophysics
by Manabu Sakamoto
1y ago
I present a Bayesian phylogenetic predictive modelling (PPM) framework that allows the prediction of muscle parameters (physiological cross-sectional area, APhys) in extinct archosaurs from skull width (WSk) and phylogeny. This approach is robust to phylogenetic uncertainty and highly versatile given its ability to base predictions on simple, readily available predictor variables. The PPM presented here has high prediction accuracy (up to 95%), with downstream biomechanical modelling yielding bite force estimates that are in line with previous estimates based on muscle parameters from reconstr ..read more
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Effects of aerobic exercise on event-related potentials related to cognitive performance: a systematic review
PeerJ » Biophysics
by Julia Gusatovic, Mathias Holsey Gramkow, Steen Gregers Hasselbalch, Kristian Steen Frederiksen
1y ago
Introduction Aerobic exercise interventions may affect different cognitive domains such as attention, working memory, inhibition, etc. However, the neural mechanisms underlying this relationship, remains uncertain. Objective To perform a systematic review on exercise intervention studies that use event-related potentials (ERPs) as outcome for cognitive performance. Methods We identified studies through searches in four databases reporting the effects of either an acute bout or chronic exercise on any ERP associated with cognitive performance. Study population included participants >17 years ..read more
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