BACKGROUND:Prior studies have identified individual risk factors that are associated with necrotizing enterocolitis (NEC); however, the small sample sizes of these previous studies have not allowed the analysis of potential interaction between multiple variables and NEC. Our purpose was to describe the incidence and risk factors for NEC in premature neonates admitted for intensive care. METHODS:We identified neonates as having NEC if they met accepted diagnostic criterion for necrotizing enterocolitis. Using a national database, we assessed the association between NEC and a battery of risk factors previously reported in peer-reviewed literature. RESULTS:There were 15,072 neonates that met inclusion criteria; 14,682 did not have NEC, while 390 (2.6%) met criterion for NEC. Multivariate analysis showed that low birth weight was the most important risk factor for NEC. Other factors that were associated with an increased risk of NEC were exposure to antenatal glucocorticoids, vaginal delivery, need for mechanical ventilator support, exposure to both glucocorticoids and indomethacin during the first week of life, absence of an umbilical arterial catheter, and low Apgar score at 5 minutes. Length of hospital stay and mortality were higher in neonates with NEC than in neonates without NEC. CONCLUSIONS:NEC remains an important cause of morbidity and mortality in prematurely born neonates. In contrast to previous studies, we found that exposure to antenatal glucocorticoids was associated with an increased risk for NEC independent of birth weight.

This article presents the results of a study on patients with diabetic neuropathy to find the relationships between the foot pressures characterized by power ratio (PR), foot sole hardness (Shore values), and foot sole soft tissue thickness. The results showed that the increase in PR values for diabetic patients in the upper sensation loss levels (S = 7.5 to 10 g) compared to the corresponding increase in lower sensation loss (S=3 to 4.5 g)were of the order of 5 times in the lateral heel and big toe, respectively, and 4 times in the first metatarsal head regions. The increase in PR values for diabetic patients in the upper Shore value regions (30 to 40) compared to the corresponding increase in lower Shore value regions (20 to 30) were of the order of 3.4 times in lateral heel and 2.4, 2.0, and 2.3 times in the first, second, and lateral metatarsal head regions, respectively. At sites contiguous to frank ulcers for foot sole hardness (Shore values of 50) at sensation level > 10 g PR was as high as 59, and foot sole thickness values were also greater than the corresponding normal values. The study shows all measured parameters may play a part in the development of plantar ulcers.

In diabetic neuropathic subjects, the hardness of foot sole soft tissue increases, and its thickness reduces, in different foot sole areas. Finite element analysis (FEA) of a three-dimensional two-arch model of the foot was performed to evaluate the effect of foot sole stresses on plantar ulcer development. Three sets of foot sole soft-tissue properties, i.e. isotropic (with control hardness value), diabetic isotropic (with higher hardness value) and anisotropic diabetic conditions, were simulated in the push-off phase, with decreasing foot sole soft-tissue thicknesses in the forefoot region, and the corresponding stresses were calculated. The results of the stress analyses for diabetic subject (anisotropic) foot models showed that, with non-uniformly increased hardness and decreased foot sole soft-tissue thickness, the normal and shear stresses at the foot sole increased (compared with control values) by 52.6% and 53.4%, respectively. Stress analyses also showed high ratios of gradients of normal and shear stresses of the order of 6.6 and 3.3 times the control values on the surface of the foot sole, and high relative values of stress gradients for normal and shear stresses of 6.25 and 4.35 times control values, respectively, between the foot sole surface and the adjacent inner layer of the foot sole, around a particular region of the foot sole with anisotropic properties. These ratios of high gradients and relative gradients of stresses due to changes in soft-tissue properties may be responsible for the development of plantar ulcers in diabetic neuropathic feet.

No abstract

Viable articular cartilage from the medial femoral condyles of rabbits was stored in vitro in tissue culture medium with various additives and the same site of each specimen was mechanically tested sequentially throughout a 12-day storage period. Indentation testing was performed with instantaneous and sustained loads. Preservation of sustained-load carrying capacity was observed in the condyles stored with additives, indicating maintenance of an intact cartilage matrix. However, initial testing with small sustained loads (preload) showed changes not observed at higher load levels. The changes noted at small sustained initial loads may reflect alterations in cartilage surface structure and may be an early indicator of its mechanical integrity. Chondrocyte viability and proteoglycan content, as measured by 35S incorporation and hexosamine concentration, were unchanged in comparison to fresh articular cartilage.