Scalable production of pancreatic islet progenitors for diabetes cell therapies

Embryonic stem cells (ESCs) can be an inexhaustible source of islet cells for transplantation. Previously published protocols have been characterized by low differentiation efficiency. In this study, we developed a scalable system for the growth and differentiation of hESCs towards pancreatic islets. Our results showed that hESCs can be grown on microcarriers to a larger scale and directed to differentiate into pancreatic progenitor endoderm cells. This culture system would represent an economical differentiation protocol that can be scaled-up to meet the demand in islet transplantation.

New observational constraints for atmospheric hydroxyl on global and hemispheric scales

Dramatic declines in emissions of methyl chloroform (1,1, 1-trichloroethane) resulting from the Montreal Protocol provide an unprecedented opportunity to improve our understanding of the oxidizing power of Earth's atmosphere. Atmospheric observations of this industrial gas during the late 1990s yield new insights into the global burden and distribution of the hydroxyl radical. Our results set firm upper limits on the global and Southern Hemispheric lifetimes of methyl chloroform and confirm the predominance of hydroxyl in the tropics. Our analysis suggests a global lifetime for methyl chloroform of 5.2 (+0.2, -0.3) years, a Southern Hemispheric lifetime of 4.9 (+0.2, -0.3) years, and mean annual concentrations of OH that are 15 +/- 10% higher south of the intertropical convergence zone than those north of this natural mixing boundary between the hemispheres.

Decline in the Tropospheric Abundance of Halogen from Halocarbons: Implications for Stratospheric Ozone Depletion

Analyses of air sampled from remote locations across the globe reveal that tropospheric chlorine attributable to anthropogenic halocarbons peaked near the beginning of 1994 and was decreasing at a rate of 25 ± 5 parts per trillion per year by mid-1995. Although bromine from halons was still increasing in mid-1995, the summed abundance of these halogens in the troposphere is decreasing. To assess the effect of this trend on stratospheric ozone, estimates of the future stratospheric abundance of ozone-depleting gases were made for mid-latitude and polar regions on the basis of these tropospheric measurements. These results suggest that the amount of reactive chlorine and bromine will reach a maximum in the stratosphere between 1997 and 1999 and will decline thereafter if limits outlined in the adjusted and amended Montreal Protocol on Substances That Deplete the Ozone Layer are not exceeded in future years.