A numerical model of cellular blebbing: A volume-conserving,fluid–structure interaction model of the entire cell

In animal cells, blebs are smooth, quasi-hemispherical protrusions of the plasma membrane that form when a section of the membrane detaches from the underlying actin cytoskeleton and is inflated by flowing cytosol. The mechanics behind this common cellular activity are not yet clear. As a first step in the development of a full computational framework, we present a numerical model of overall cell behavior based upon the interaction between a background Newtonian-fluid cytosol and elastic structures modeling the membrane and filaments. The detailed micromechanics of the cytoskeletal network are the subject of future work. Here, the myosin-driven contraction of the actin network is modeled through stressed elastic filaments. Quantitative models of cytoskeletal micromechanics and biochemistry require accurate estimates of local stress and flow conditions. The main contribution of this paper is the development of a computationally efficient fluid–structure interaction model based on operator splitting, to furnish this data. Cytosol volume conservation (as supported by experimental evidence) is enforced through an intermediate energy minimization step. Realistic bleb formation and retraction is observed from this model, offering an alternative formulation to positing complex continuum behavior of the cytoplasm (e.g. poroelastic model of Charras et al., 2008).     

Comparative Effects of Boric Acid and Calcium Fructoborate on Breast Cancer Cells

Recent studies suggested that boron has a chemo-preventive role in prostate cancer. In the present report, we investigated the effects of calcium fructoborate (CF) and boric acid (BA) on activation of the apoptotic pathway in MDA-MB-231 human breast cancer cells. Exposure to BA and CF inhibited the proliferation of breast cancer cells in a dose-dependent manner. Treatment with CF but not BA resulted in a decrease in p53 and bcl-2 protein levels. Furthermore, after the treatment with CF, augmentation of pro-caspase-3 protein expression, cytosolic cytochrome c level, and caspase-3 activity were observed, indicating apoptotic cell death induction. This was also demonstrated by terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick-end-labeling assay. In conclusion, our data provide arguments to the fact that both BA and CF inhibited the growth of breast cancer cells, while only CF induced apoptosis. Additional studies will be needed to identify the underlying mechanism responsible for the observed cellular responses to these compounds and to determine if BA and CF may be further evaluated as chemotherapeutic agents for human cancer.     

In Vitro Effects of Calcium Fructoborate upon Production of Inflammatory Mediators by LPS-stimulated RAW 264.7 Macrophages

The present study is supported by our previous findings suggesting that calcium fructoborate (CF) has anti-inflammatory and antioxidant properties. Thus, we investigated the effects of CF on a model for studying inflammatory disorders in vitro represented by lipopolysaccharide (LPS)-stimulated murine macrophage RAW 264.7 cells. This investigation was performed by analyzing the levels of some mediators released during the inflammatory process: cytokines such as tumor necrosis factor-α (TNF-α), interleukins IL-1β and IL-6 as well as cyclooxygenase-2 (COX-2), the main enzyme responsible for endotoxin/LPS-induced prostaglandin synthesis by macrophages. We also measured production of nitric oxide (NO) that plays an important role in the cytotoxicity activity of macrophages towards microbial pathogens. After CF treatment of LPS-stimulated macrophages we found an up-regulation of TNF-α protein level in culture medium, no significant changes in the level of COX-2 protein expression and a decrease in NO production as well as in IL-1β and IL-6 release. Collectively, this series of experiments indicate that CF affect macrophage production of inflammatory mediators. However, further research is required in order to establish whether CF treatment can be beneficial in suppression of pro-inflammatory cytokine production and against progression of endotoxin-related diseases.     

In Vitro Effects of Calcium Fructoborate on fMLP-stimulated Human Neutrophil Granulocytes

Discovery of naturally occurring boron complexes with organic compounds containing hydroxyl groups, sugars, and polysaccharides, adenosine-5-phosphate, pyridoxine, riboflavin, dehydroascorbic acid, and pyridine nucleotides led to the reassessment of the biochemical role of boron. Boron’s anti-inflammatory actions were claimed but not yet demonstrated. This study investigated the effects of calcium fructoborate (CF) on the human polymorphonuclear neutrophils (PMN) that play a central role in the inflammatory response. Our results demonstrated that CF exposure induced a dose-dependent decrease in cell viability. Treatment of PMN cells, for 24 h, with 22,500 μM CF led to a decrease in cell viability by 61.1%, an inhibition of respiratory burst by 92.9% in the case of fMLP-stimulated cells, a diminution of intracellular level of superoxide anion with 59.3%, and a stimulation of superoxide dismutase activity by 72% in unstimulated PMN cells. Altogether, these results suggest the antioxidant and anti-inflammatory properties of CF.     

Response and interaction of <Emphasis Type="Italic">Bradyrhizobium japonicum</Emphasis> and arbuscular mycorrhizal fungi in the soybean rhizosphere

Regulatory response and interaction of Bradyrhizobium and arbuscular mycorrhizal fungi (AMF) play a vital role in rhizospheric soil processes and productivity of soybean (Glycine max L.). Nitrogen (N) and phosphorus (P) are essential nutrients for plant growth and productivity, the synergistic interaction(s) of AMF and Bradyrhizobium along with rhizospheric beneficial microorganisms stimulate soybean growth and development through enhanced mineral nutrient acquisition (N and P) and improved rhizosphere environment. Such interactions are crucial, especially under low-input eco-friendly agricultural cropping systems, which rely on biological processes rather than agrochemicals to maintain soil quality, sustainability, and productivity. Furthermore, enhancement of N-fixation by root nodules along with AMF-mediated synergism improves plant P nutrition and uptake, and proliferation of phosphate-solubilizing fungi. However, the genetic and/or allelic diversity among native strains, their genes/enzymes and many environmental factors (e.g., soil organic matter, fertilizers, light, temperature, soil moisture, and biotic interactors) affect the interactions between AMF and Bradyrhizobium. New information is available regarding the genetic composition of elite soybean inoculant strains in maximizing symbiotic performance, N-fixing capabilities and depending on N and P status the host-mediated regulation of root architecture. Overall, for sustainable soybean production systems, a deeper understanding of the interaction effects of Bradyrhizobium and AMF co-inoculation are expected in the future, so that optimized combinations of microorganisms can be applied as effective soil inoculants for plant growth promotion and fitness. The objective of this review is to offer insights into the mechanistic interactions of AMF and Bradyrhizobium and rhizopheric soil health, and elucidate the role of environmental factors in regulating growth, development and sustainable soybean productivity.     

Calculation of viscoelastic bead–rod flow mediated by a homogenised kinetic scale with holonomic constraints

We present a new multiscale model for complex fluids based on three scales: microscopic, kinetic and continuum. We choose the microscopic level as Kramers' bead–rod model for polymers, which we describe as a system of stochastic differential equations with an implicit constraint formulation. The associated Fokker–Planck equation is then derived, and adiabatic elimination removes the fast momentum coordinates. Approached in this way, the kinetic level reduces to a dispersive drift equation. The continuum level is modelled with a finite volume Godunov-projection algorithm. We demonstrate the computation of viscoelastic stress divergence using this multiscale approach.     

Enhanced Wound Healing Activity of Undenatured Type I Collagen Isolated from Discarded Skin of Black Sea Gilthead Bream (Sparus aurata) Conditioned as 3D Porous Dressing

Acid-soluble, undenatured, type I collagen (BSC) isolated, for the first time, from gilthead bream skin and the novel fabricated 3D porous wound dressing were analyzed for physicochemical and biological properties, in order to offer a safe alternative to commercial bovine collagen (BC) products. SDS-polyacrylamide analysis confirmed the purity of BSC preparation. The hydroxyproline content and temperature of denaturation of BSC were lower than those of BC, in accordance with the structural data recorded by FT-IR spectroscopy. However, certain concentrations of BSC stimulated the cell metabolism of L929 fibroblasts in a higher proportion than BC. The 3D wound dressing presented high porosity and low surface hydrophobicity that could help cell attachment and growth. The rapid biodegradation of BSC wound dressing could explain the improved in vitro cell migration and wound closure rate. In conclusion, the skin of gilthead bream from the Black Sea coast represented a valuable source for the biomedical industry, providing biocompatible, biodegradable collagen and 3D porous wound dressing, as novel material with enhanced wound healing activity.