In humans, two genetic studies tested the association between NOD2 and risk of NEC showing that genetic polymorphisms of Nod2 are not associated with NEC or prematurity. These results suggest that in the preterm intestinal mucosa, upregulation of the innate responses occurs early before histological lesions arise. The immature fetal small Polyphyllin-II intestine has an excessive response to Schisandrol-B mucosal injury compared with the small intestines of full-term pups. Prematurity may thus render the neonatal digestive tract more susceptible to mucosal barrier failure and lead to NEC if associated with other risk factors. The IEC phenotype obtained in this rat model of NEC is very close to those observed in fetal IEC, thus suggesting that NEC could result in abnormal maintenance of a fetal phenotype in IEC. Hostintraluminal bacteria interactions and bacterial-derived products activate TLR on intestinal epithelial cells that are abnormally upregulated following neonatal stress, resulting in downstream inflammatory gene expression and NEC and bowel injury. Following incision of the abdomen, the small intestine was evaluated visually for typical gross signs of NEC such as intestinal distension, intestinal wall hemorrhages, or necrosis. The entire small intestine was harvested and 20-mm lengths of the distal jejunum and distal ileum were taken. Half of each sample was immediately snap frozen in nitrogen for the immunohistochemical and RT-PCR studies, whereas the other half was formalin-fixed, paraffin-embedded, microtome-sectioned at 5 mm, and stained with hematoxylin and eosin for histological evaluation. Nuclear magnetic resonance relaxation is a powerful tool for understanding the structure and dynamics of proteins. In the most common approach to the analysis of protein dynamics, relaxation data �C in the form of longitudinal relaxation rates, transverse relaxation rates, and heteronuclear NOEs �C are used to derive microdynamic parameters that describe both the overall tumbling and the internal motions of a macromolecule.In the ��model-free�� approach, the internal dynamics are quantified using a generalized order parameter, S2, which characterizes the amplitude of motion, and an internal correlation time ti. Additional parameters can be introduced to account for internal motions on fast and slow timescales. Several computer programs have been developed to analyze relaxation data and generate the parameters that describe the rates and amplitudes of protein motions, including Modelfree, relax and MOLDYN.