Search results for "biophysics"

A versatile bioreactor for dynamic suspension cell culture. Application to the culture of cancer cell spheroids.

2016

A versatile bioreactor suitable for dynamic suspension cell culture under tunable shear stress conditions has been developed and preliminarily tested culturing cancer cell spheroids. By adopting simple technological solutions and avoiding rotating components, the bioreactor exploits the laminar hydrodynamics establishing within the culture chamber enabling dynamic cell suspension in an environment favourable to mass transport, under a wide range of tunable shear stress conditions. The design phase of the device has been supported by multiphysics modelling and has provided a comprehensive analysis of the operating principles of the bioreactor. Moreover, an explanatory example is herein prese…

Role of pulmonary surfactant protein Sp-C dimerization on membrane fragmentation: An emergent mechanism involved in lung defense and homeostasis.

2020

Surfactant protein C (SP-C) is a protein present in the pulmonary surfactant system that is involved in the biophysical properties of this lipoprotein complex, but it also has a role in lung defense and homeostasis. In this article, we propose that the link between both functions could rely on the ability of SP-C to induce fragmentation of phospholipid membranes and generate small vesicles that serve as support to present different ligands to cells in the lungs. Our results using bimolecular fluorescence complementation and tunable resistive pulse sensing setups suggest that SP-C oligomerization could be the triggering event that causes membrane budding and nanovesiculation. As shown by flu…

Lipid peroxidation as measured by chromatographic determination of malondialdehyde. Human plasma reference values in health and disease

2021

Free radicals and oxidants are involved in physiological signaling pathways, although an imbalance between pro-oxidant and anti-oxidant systems in favor of the former leads to major biomolecular damage. This is the so-called oxidative stress, a complex process that affects us all and is responsible for the development of many diseases. Lipids are very sensitive to oxidant attack and to-date, malondialdehyde (MDA), 4-hydroxy-2-nonenal (4-HNE) and F2-isoprostane are the main biomarkers for lipid peroxidation assessment. They all derive from polyunsaturated fatty acids (PUFAs) either by enzyme-catalyzed reactions (physiological) or by non-enzyme reactions (pathological). The profile of PUFAs p…

Dry selection and wet evaluation for the rational discovery of new anthelmintics

2017

Helminths infections remain a major problem in medical and public health. In this report, atom-based 2D bilinear indices, a TOMOCOMD-CARDD (QuBiLs-MAS module) molecular descriptor family and linear discriminant analysis (LDA) were used to find models that differentiate among anthelmintic and non-anthelmintic compounds. Two classification models obtained by using non-stochastic and stochastic 2D bilinear indices, classified correctly 86.64% and 84.66%, respectively, in the training set. Equation 1(2) correctly classified 141(135) out of 165 [85.45%(81.82%)] compounds in external validation set. Another LDA models were performed in order to get the most likely mechanism of action of anthelmin…

Skin-derived mesenchymal stem cells as quantum dot vehicles to tumors

2017

Dominyka Dapkute,1,2 Simona Steponkiene,1 Danute Bulotiene,1 Liga Saulite,3 Una Riekstina,3 Ricardas Rotomskis1,4 1Biomedical Physics Laboratory, National Cancer Institute, Vilnius, Lithuania; 2Institute of Biosciences, Vilnius University, Vilnius, Lithuania; 3Faculty of Medicine, University of Latvia, Riga, Latvia; 4Biophotonics Group of Laser Research Center, Faculty of Physics, Vilnius University, Vilnius, Lithuania Purpose: Cell-mediated delivery of nanoparticles is emerging as a new method of cancer diagnostics and treatment. Due to their inherent regenerative properties, adult mesenchymal stem cells (MSCs) are naturally attracted to wounds and sites of inflammation, as well as tumors.…

Morphogenetically-Active Barrier Membrane for Guided Bone Regeneration, Based on Amorphous Polyphosphate

2017

We describe a novel regeneratively-active barrier membrane which consists of a durable electrospun poly(ε-caprolactone) (PCL) net covered with a morphogenetically-active biohybrid material composed of collagen and inorganic polyphosphate (polyP). The patch-like fibrous collagen structures are decorated with small amorphous polyP nanoparticles (50 nm) formed by precipitation of this energy-rich and enzyme-degradable (alkaline phosphatase) polymer in the presence of calcium ions. The fabricated PCL-polyP/collagen hybrid mats are characterized by advantageous biomechanical properties, such as enhanced flexibility and stretchability with almost unaltered tensile strength of the PCL net. The pol…

2016

Orthopedic implant failure due to aseptic loosening and mechanical instability remains a major problem in total joint replacement. Improving osseointegration at the bone-implant interface may reduce micromotion and loosening. Bone sialoprotein (BSP) has been shown to enhance bone formation when coated onto titanium femoral implants and in rat calvarial defect models. However, the most appropriate method of BSP coating, the necessary level of BSP coating, and the effect of BSP coating on cell behavior remain largely unknown. In this study, BSP was covalently coupled to titanium surfaces via an aminosilane linker (APTES), and its properties were compared to BSP applied to titanium via physiso…

Microenvironments to study migration and somal translocation in cortical neurons

2018

Migrating post-mitotic neurons of the developing cerebral cortex undergo terminal somal translocation (ST) when they reach their final destination in the cortical plate. This process is crucial for proper cortical layering and its perturbation can lead to brain dysfunction. Here we present a reductionist biomaterials platform that faithfully supports and controls the distinct phases of terminal ST in vitro. We developed microenvironments with different adhesive molecules to support neuronal attachment, neurite extension, and migration in distinct manners. Efficient ST occurred when the leading process of migratory neurons crossed from low-to high-adhesive areas on a substrate, promoting spr…

The tumour microenvironment as an integrated framework to understand cancer biology

2019

Cancer cells all share the feature of being immersed in a complex environment with altered cell-cell/cell-extracellular element communication, physicochemical information, and tissue functions. The so-called tumour microenvironment (TME) is becoming recognised as a key factor in the genesis, progression and treatment of cancer lesions. Beyond genetic mutations, the existence of a malignant microenvironment forms the basis for a new perspective in cancer biology where connections at the system level are fundamental. From this standpoint, different aspects of tumour lesions such as morphology, aggressiveness, prognosis and treatment response can be considered under an integrated vision, givin…

Specific interaction of IM30/Vipp1 with cyanobacterial and chloroplast membranes results in membrane remodeling and eventually in membrane fusion.

2016

The photosynthetic light reaction takes place within the thylakoid membrane system in cyanobacteria and chloroplasts. Besides its global importance, the biogenesis, maintenance and dynamics of this membrane system are still a mystery. In the last two decades, strong evidence supported the idea that these processes involve IM30, the inner membrane-associated protein of 30kDa, a protein also known as the vesicle-inducing protein in plastids 1 (Vipp1). Even though we just only begin to understand the precise physiological function of this protein, it is clear that interaction of IM30 with membranes is crucial for biogenesis of thylakoid membranes. Here we summarize and discuss forces guiding I…