In selecting a method to produce a recombinant protein, a researcher is faced with a bewildering array of choices as to where to start. To facilitate decision-making, we describe a consensus 'what to try first' strategy based on our collective analysis of the expression and purification of over 10,000 different proteins. This review presents methods that could be applied at the outset of any project, a prioritized list of alternate strategies and a list of pitfalls that trip many new investigators.

Peroxisome proliferator-activated receptor-␥ coactivator 1-␣ (PGC1␣) is the primary regulator of mitochondrial biogenesis and was recently found to be highly expressed within the intestinal epithelium. PGC1␣ is decreased in the intestinal epithelium of patients with inflammatory bowel disease, but its role in pathogenesis is uncertain. We now hypothesize that PGC1␣ protects against the development of colitis and helps to maintain the integrity of the intestinal barrier. We selectively deleted PGC1␣ from the intestinal epithelium of mice by breeding a PGC1␣ loxP/loxP mouse with a villin-cre mouse. Their progeny (PGC1␣ ⌬IEC mice) were subjected to 2% dextran sodium sulfate (DSS) colitis for 7 days. The SIRT1 agonist SRT1720 was used to enhance PGC1␣ activation in wild-type mice during DSS exposure. Mice lacking PGC1␣ within the intestinal epithelium were more susceptible to DSS colitis than their wild-type littermates. Pharmacologic activation of PGC1␣ successfully ameliorated disease and restored mitochondrial integrity. These findings suggest that a depletion of PGC1␣ in the intestinal epithelium contributes to inflammatory changes through a failure of mitochondrial structure and function as well as a breakdown of the intestinal barrier, which leads to increased bacterial translocation. PGC1␣ induction helps to maintain mitochondrial integrity, enhance intestinal barrier function, and decrease inflammation.

Background Necrotizing enterocolitis (NEC) is a severe intestinal disease of premature infants with high mortality. Studies suggest a causative relationship between red blood cell (RBC) transfusion and NEC, however, whether RBC transfusion leads to worse outcomes in NEC is unknown. We sought to determine whether RBC transfusion was associated with an increased risk of surgical NEC and mortality. Methods In this retrospective study, 115 patients were enrolled with NEC Bell’s Stage 2A or greater from 2010–2015. Patients were classified based on the timing of RBC transfusion prior to NEC: ≤72 hours, >72 hours, and no transfusion. Variables including gestational age (GA), birth weight (BW), feedings and hematocrit levels were analyzed. Outcomes were surgical intervention for NEC following RBC transfusion and mortality. Results 23 (20%) infants developed NEC ≤ 72 hours after RBC transfusion, 16 (69.6%) required surgery with a mortality rate of 21.7% (n=5). 17 (15%) infants developed NEC > 72 hours after RBC transfusion, 12 (70.6%) required surgery with a mortality rate of 23.5% (n=4). 75 (65%) patients developed NEC without RBC transfusion, 17 (22.7%) required surgery with a mortality rate of 4% (n=3). Lower GA and BW were significantly associated with RBC transfusion and the need for surgical intervention. RBC transfusion ≤72 hours prior to NEC was associated with surgical NEC (pairwise adjusted p<0.001) and mortality (pairwise adjusted p=0.048). However, multivariable logistic regression analysis revealed RBC transfusion is not an independent risk factor for surgical NEC. Conclusions Infants of lower GA and BW were more likely to receive an RBC transfusion prior to NEC, which was significantly associated with surgical intervention and an increasing risk of mortality. Judicious use of transfusions in premature infants may improve NEC outcomes.

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