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Gamma-ray bursts (GRBs) are immensely powerful explosions, originating at cosmological distances, whose outbursts persist for durations ranging from milliseconds to tens of seconds or more. In these brief moments, the explosions radiate more energy than the Sun will release in its entire 10Gyr lifetime. Current theories attribute these phenomena to the final collapse of a massive star, or the coalescence of a binary system induced by gravity wave emission.New results from Swift and related programmes offer fresh understanding of the physics of GRBs, and of the local environments and host galaxies of burst progenitors. Bursts found at very high red shifts are new tools for exploring the intergalactic medium, the first stars and the earliest stages of galaxy formation.This Royal Society Discussion Meeting has brought together leading figures in the field, together with young researchers and students, to discuss and review the latest results from NASA's Swift Gamma-ray Burst Observatory and elsewhere, and to examine their impact on current understanding of the observed phenomena. [ABSTRACT FROM AUTHOR]

Smooth muscle cells (SMCs) are major components of blood vessels and other hollow visceral organs required for tissue engineering of these organs. This study aims to evaluate whether adult bone marrow-derived mesenchymal stem cells (BMMSCs), multipotent cells, can be converted into SMCs. We examined the ERK/MAPK pathway as it exerts anti-myogenic signals in SMCs. Undifferentiated BMMSCs express most SMC marker genes, albeit mainly at low levels, except smooth muscle myosin heavy chain (SMMHC), the most definitive marker of differentiated SMC. The treatment of BMMSC with MEK inhibitor up-regulated the expression of alpha-smooth muscle actin (ASMA), h-caldesmon, and SMMHC in BMMSC in low serum condition. MEK inhibitor-treated BMMSC also contracted a collagen gel in response to endothelin. Interestingly, inhibition of MEK induced myocardin expression in BMMSC. In conclusion, BMMSCs treated MEK inhibitor gain a SMC-like phenotype with ligand-induced cell contractility to endothelin in vitro. This approach has obvious implications for cell therapeutics and tissue engineering of hollow visceral organs such as blood vessels. [ABSTRACT FROM AUTHOR]