Ser(756) of β2 integrin controls Rap1 activity during inside-out activation of αMβ2

During αMβ2-mediated phagocytosis, the small GTPase Rap1 activates the β2 integrin by binding to a region between residues 732 and 761. Using COS-7 cells transfected with αMβ2, we show that αMβ2 activation by the phorbol ester PMA involves Ser756 of β2. This residue is critical for the local positioning of talin and biochemically interacts with Rap1. Using the CaM (calmodulin) antagonist W7, we found Rap1 recruitment and the inside-out activation of αMβ2 to be affected. We also report a role for CaMKII (calcium/CaM-dependent kinase II) in the activation of Rap1 during integrin activation. These results demonstrate a distinct physiological role for Ser756 of β2 integrin, in conjunction with the actions of talin and Rap1, during αMβ2 activation in macrophages

Enteral Feeding during Indomethacin and Ibuprofen Treatment of a Patent Ductus Arteriosus

ObjectiveTo test the hypothesis that infants who are just being introduced to enteral feedings will advance to full enteral nutrition at a faster rate if they receive "trophic" (15 mL/kg/d) enteral feedings while receiving indomethacin or ibuprofen treatment for patent ductus arteriosus.Study designInfants were eligible for the study if they were 23(1/7)-30(6/7) weeks' gestation, weighed 401-1250 g at birth, received maximum enteral volumes ≤60 mL/kg/d, and were about to be treated with indomethacin or ibuprofen. A standardized "feeding advance regimen" and guidelines for managing feeding intolerance were followed at each site (N = 13).ResultsInfants (N = 177, 26.3 ± 1.9 weeks' mean ± SD gestation) were randomized at 6.5 ± 3.9 days to receive "trophic" feeds ("feeding" group, n = 81: indomethacin 80%, ibuprofen 20%) or no feeds ("fasting [nil per os]" group, n = 96: indomethacin 75%, ibuprofen 25%) during the drug administration period. Maximum daily enteral volumes before study entry were 14 ± 15 mL/kg/d. After drug treatment, infants randomized to the "feeding" arm required fewer days to reach the study's feeding volume end point (120 mL/kg/d). Although the enteral feeding end point was reached at an earlier postnatal age, the age at which central venous lines were removed did not differ between the 2 groups. There were no differences between the 2 groups in the incidence of infection, necrotizing enterocolitis, spontaneous intestinal perforation, or other neonatal morbidities.ConclusionInfants required less time to reach the feeding volume end point if they were given "trophic" enteral feedings when they received indomethacin or ibuprofen treatments

Enteral Feeding during Indomethacin and Ibuprofen Treatment of a Patent Ductus Arteriosus

OBJECTIVE: To test the hypothesis that infants who are just being introduced to enteral feedings will advance to full enteral nutrition at a faster rate if they receive “trophic” (15 ml/kg/day) enteral feedings while receiving indomethacin or ibuprofen treatment for patent ductus arteriosus (PDA). STUDY DESIGN: Infants were eligible for the study if they were 23(1/7) – 30(6/7) weeks gestation, weighed 401–1250 g at birth, received maximum enteral volumes ≤60 ml/kg/day and were about to be treated with indomethacin or ibuprofen. A standardized “feeding advance regimen” and guidelines for managing feeding intolerance were followed at each site (n=13). RESULTS: Infants (n=177; 26.3±1.9 wks (±SD) gestation) were randomized at 6.5±3.9 days to receive “trophic” feeds (“feeding” group, n=81: indomethacin=80%, ibuprofen=20%) or no feeds (“fasting (npo)” group, n=96: indomethacin=75%, ibuprofen=25%) during the drug administration period. Maximum daily enteral volumes prior to study entry were 14±15 ml/kg/day. After drug treatment, infants randomized to the “feeding” arm required fewer days to reach the study’s feeding volume endpoint (120 ml/kg/day). Although the enteral feeding endpoint was reached at an earlier postnatal age, the age at which central venous lines were removed did not differ between the two groups. There were no differences between the two groups in the incidence of infection, necrotizing enterocolitis, spontaneous intestinal perforation or other neonatal morbidities. CONCLUSION: Infants required less time to reach the feeding volume endpoint if they were given “trophic” enteral feedings when they received indomethacin or ibuprofen treatments