Degradable emulsion-templated scaffolds for tissue engineering from thiol– ene photopolymerisation

Emulsion templating has been used to prepare highly porous polyHIPE materials by thiol–ene photoinitiated network formation. Commercially available multifunctional thiols and acrylates were formulated into water-in-oil high internal phase emulsions (HIPEs) using an appropriate surfactant, and the HIPEs were photo-cured. The temperature of the HIPE aqueous phase was found to influence the morphology of the resulting materials. In agreement with previous work, a higher aqueous phase temperature (80 °C) gave rise to a larger mean void and interconnect diameter. The influence of temperature on morphology was found to be reduced at higher porosity, but still significant. The Young's modulus of the porous materials was shown to be related to the functionality of the acrylate comonomer used. A mixture of penta- and hexa-acrylate gave rise to a 100-fold increase in modulus, compared to an analogous tri-functional acrylate. The materials could be functionalised conveniently by addition of mono-acrylates or thiols to the organic phase of the precursor HIPE. Degradation was observed to occur at a rate depending on the degradation conditions. Under cell culture conditions at 37 °C, 19% mass loss occurred over 15 weeks. The scaffolds were found to be capable of supporting the growth of keratinocytic cells (HaCaTs) over 11 days in culture. Some penetrative in-growth of the cells into the scaffold was observed

Deville rebooted – practical N 2 O 5 synthesis †

Dinitrogen pentoxide (N2O5), the anhydride of nitric acid, was synthesised by Henri Étienne Sainte-Claire Deville in Paris in 1849 using silver nitrate and chlorine gas. Herein, we revisit, optimise, and modify Deville's method using photocatalysis to enable a safe, clean, practical, and reproducible alternative for N2O5 synthesis in quantitative yields. Moreover, it is predicted that the modifications can accommodate an industrial scale-up, but the silver chloride generated must be recycled

The priming effect of extracellular UTP on human neutrophils: Role of calcium released from thapsigargin-sensitive intracellular stores

P2Y2 receptors, which are equally responsive to ATP and UTP, can trigger intracellular signaling events, such as intracellular calcium mobilization and mitogen-activated protein (MAP) kinase phosphorylation in polymorphonuclear leukocytes (PMN). Moreover, extracellular nucleotides have been shown to prime chemoattractant-induced superoxide production. The aim of our study was to investigate the mechanism responsible for the priming effect of extracellular nucleotides on reactive oxygen species (ROS) production induced in human neutrophils by two different chemoattractants: formyl-methionyl-leucyl-phenylalanine (fMLP) and interleukin-8 (IL-8). Nucleotide-induced priming of ROS production was concentration- and time-dependent. When UTP was added to neutrophil suspensions prior to chemoattractant, the increase of the response reached the maximum at 1 min of pre-incubation with the nucleotide. UTP potentiated the phosphorylation of p44/42 and p38 MAP kinases induced by chemoattractants, however the P2 receptor-mediated potentiation of ROS production was still detectable in the presence of a SB203580 or U0126, supporting the view that MAP kinases do not play a major role in regulating the nucleotide-induced effect. In the presence of thapsigargin, an inhibitor of the ubiquitous sarco-endoplasmic reticulum Ca2+-ATPases in mammalian cells, the effect of fMLP was not affected, but UTP-induced priming was abolished, suggesting that the release of calcium from thapsigargin-sensitive intracellular stores is essential for nucleotide-induced priming in human neutrophils

Chronic Granulomatous Disease; fundamental stages in our understanding of CGD

It has been 50 years since chronic granulomatous disease was first reported as a disease which fatally affected the ability of children to survive infections. Various milestone discoveries from the insufficient ability of patients' leucocytes to destroy microbial particles to the underlying genetic predispositions through which the disease is inherited have had important consequences. Longterm antibiotic prophylaxis has helped to fight infections associated with chronic granulomatous disease while the steady progress in bone marrow transplantation and the prospect of gene therapy are hailed as long awaited permanent treatment options. This review unearths the important findings by scientists that have led to our current understanding of the disease

Rac and Rho GTPases in cancer cell motility control

Rho GTPases represent a family of small GTP-binding proteins involved in cell cytoskeleton organization, migration, transcription, and proliferation. A common theme of these processes is a dynamic reorganization of actin cytoskeleton which has now emerged as a major switch control mainly carried out by Rho and Rac GTPase subfamilies, playing an acknowledged role in adaptation of cell motility to the microenvironment. Cells exhibit three distinct modes of migration when invading the 3 D environment. Collective motility leads to movement of cohorts of cells which maintain the adherens junctions and move by photolytic degradation of matrix barriers. Single cell mesenchymal-type movement is characterized by an elongated cellular shape and again requires extracellular proteolysis and integrin engagement. In addition it depends on Rac1-mediated cell polarization and lamellipodia formation. Conversely, in amoeboid movement cells have a rounded morphology, the movement is independent from proteases but requires high Rho GTPase to drive elevated levels of actomyosin contractility. These two modes of cell movement are interconvertible and several moving cells, including tumor cells, show an high degree of plasticity in motility styles shifting ad hoc between mesenchymal or amoeboid movements. This review will focus on the role of Rac and Rho small GTPases in cell motility and in the complex relationship driving the reciprocal control between Rac and Rho granting for the opportunistic motile behaviour of aggressive cancer cells. In addition we analyse the role of these GTPases in cancer progression and metastatic dissemination

Pathogens and polymers: Microbe–host interactions illuminate the cytoskeleton

Intracellular pathogens subvert the host cell cytoskeleton to promote their own survival, replication, and dissemination. Study of these microbes has led to many discoveries about host cell biology, including the identification of cytoskeletal proteins, regulatory pathways, and mechanisms of cytoskeletal function. Actin is a common target of bacterial pathogens, but recent work also highlights the use of microtubules, cytoskeletal motors, intermediate filaments, and septins. The study of pathogen interactions with the cytoskeleton has illuminated key cellular processes such as phagocytosis, macropinocytosis, membrane trafficking, motility, autophagy, and signal transduction