Mutations in ENPP1 are associated with 'idiopathic' infantile arterial calcification

Idiopathic infantile arterial calcification (IIAC; OMIM 208000) is characterized by calcification of the internal elastic lamina of muscular arteries and stenosis due to myointimal proliferation. We analyzed affected individuals from 11 unrelated kindreds and found that IIAC was associated with mutations that inactivated ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This cell surface enzyme generates inorganic pyrophosphate (PP(i)), a solute that regulates cell differentiation and serves as an essential physiologic inhibitor of calcification.     

Low-loss hollow-core silica/air photonic bandgap fibre

Photonic bandgap structures use the principle of interference to reflect radiation. Reflection from photonic bandgap structures has been demonstrated in one, two and three dimensions and various applications have been proposed. Early work in hollow-core photonic bandgap fibre technology used a hexagonal structure surrounding the air core; this fibre was the first demonstration of light guided inside an air core of a photonic bandgap fibre. The potential benefits of guiding light in air derive from lower Rayleigh scattering, lower nonlinearity and lower transmission loss compared to conventional waveguides. In addition, these fibres offer a new platform for studying nonlinear optics in gases. Owing largely to challenges in fabrication, the early air-core fibres were only available in short lengths, and so systematic studies of loss were not possible. More recently, longer lengths of fibre have become available with reported losses of 1,000 dB km(-1). We report here the fabrication and characterization of long lengths of low attenuation photonic bandgap fibre. Attenuation of less than 30 dB km(-1) over a wide transmission window is observed with minimum loss of 13 dB km(-1) at 1,500 nm, measured on 100 m of fibre. Coupling between surface and core modes of the structure is identified as an important contributor to transmission loss in hollow-core photonic bandgap fibres.