John F. Valentine

Abstract Bioenergy from crops is expected to make a considerable contribution to climate change mitigation. However, bioenergy is not necessarily carbon neutral because emissions of CO 2 , N 2 O and CH 4 during crop production may reduce or completely counterbalance CO 2 savings of the substituted fossil fuels. These greenhouse gases ( GHG s) need to be included into the carbon footprint calculation of different bioenergy crops under a range of soil conditions and management practices. This review compiles existing knowledge on agronomic and environmental constraints and GHG balances of the major E uropean bioenergy crops, although it focuses on dedicated perennial crops such as M iscanthus and short rotation coppice species. Such second‐generation crops account for only 3% of the current E uropean bioenergy production, but field data suggest they emit 40% to >99% less N 2 O than conventional annual crops. This is a result of lower fertilizer requirements as well as a higher N‐use efficiency, due to effective N‐recycling. Perennial energy crops have the potential to sequester additional carbon in soil biomass if established on former cropland (0.44 Mg soil C ha −1 yr −1 for poplar and willow and 0.66 Mg soil C ha −1 yr −1 for M iscanthus ). However, there was no positive or even negative effects on the C balance if energy crops are established on former grassland. Increased bioenergy production may also result in direct and indirect land‐use changes with potential high C losses when native vegetation is converted to annual crops. Although dedicated perennial energy crops have a high potential to improve the GHG balance of bioenergy production, several agronomic and economic constraints still have to be overcome.

Sargramostim, granulocyte-macrophage colony-stimulating factor, a hematopoietic growth factor, stimulates cells of the intestinal innate immune system. Preliminary studies suggest sargramostim may have activity in Crohn's disease. To evaluate this novel therapeutic approach, we conducted a randomized, placebo-controlled trial.Using a 2:1 ratio, we randomly assigned 124 patients with moderate-to-severe active Crohn's disease to receive 6 mug of sargramostim per kilogram per day or placebo subcutaneously for 56 days. Antibiotics and aminosalicylates were allowed; immunosuppressants and glucocorticoids were prohibited. The primary end point was a clinical response, defined by a decrease from baseline of at least 70 points in the Crohn's Disease Activity Index (CDAI) at the end of treatment (day 57). Other end points included changes in disease severity and the health-related quality of life and adverse events.There was no significant difference in the rate of the primary end point of a clinical response defined by a decrease of at least 70 points in the CDAI score on day 57 between the sargramostim and placebo groups (54 percent vs. 44 percent, P=0.28). However, significantly more patients in the sargramostim group than in the placebo group reached the secondary end points of a clinical response defined by a decrease from baseline of at least 100 points in the CDAI score on day 57 (48 percent vs. 26 percent, P=0.01) and of remission, defined by a CDAI score of 150 points or less on day 57 (40 percent vs. 19 percent, P=0.01). The rates of either type of clinical response and of remission were significantly higher in the sargramostim group than in the placebo group on day 29 of treatment and 30 days after treatment. The sargramostim group also had significant improvements in the quality of life. Mild-to-moderate injection-site reactions and bone pain were more common in the sargramostim group, and three patients in this group had serious adverse events possibly or probably related to treatment.This study was negative for the primary end point, but findings for the secondary end points suggest that sargramostim therapy decreased disease severity and improved the quality of life in patients with active Crohn's disease.