Postnatal Exposure to Brief Hypoxia Alters Brain VEGF Expression and Capillary Density in Adult Mice.

Perinatal hypoxia leads to changes in cerebral angiogenesis and persistent structural and functional changes in the adult brain. It may also result in greater vulnerability to subsequent challenges. We investigated the effect of postnatal day 2 (P2) hypoxic preconditioning on adult brain capillary density and brain vascular endothelial growth factor (VEGF) expression in mice. P2 mice were exposed to hypoxia (5% O2) in a normobaric chamber for 2 h then returned to normoxia while their littermates remained in normoxia (P2 control). After 2-6 months, they were euthanised and their brains were removed for capillary density determination. Another set of animals (P2 hypoxic mice and P2 controls) were euthanised at 2, 10, 23, and 60 days after birth and brain VEGF expression was assessed by western blot. Adult brain capillary density was significantly increased in the P2 hypoxic mice when compared to the P2 control mice. Additionally, VEGF expression appeared to be elevated in the P2-hypoxia mice when compared to the P2-control mice at all time points, and VEGF levels in P2-hypoxia mice declined with age similarly to P2-control mice. These data demonstrate that transient early-postnatal hypoxic stress leads to an increase in capillary density that persists in the adult, possibly due to increased VEGF expression. These results might be explained by epigenetic factors in the VEGF gene.

Interfacet distance at L4 is increased in spines with high-pelvic incidence.

Pelvic incidence (PI) is an angular measurement linked to spinal pathologies. There is an increasing distance between facet joints moving caudally down the sagittal plane of the spine. We defined pedicle divergence (PD) as the ratio of interfacet distance (IFD) between adjacent levels. This study aimed to evaluate the relationship between PI and PD. Two hundred and thirty specimens were obtained from the Hamann-Todd Osteological Collection. Specimens were catalogued for age, sex, race, PI, PD, and lumbar facet angle. Multivariate linear regression analysis was performed to determine the relationship between variables. IRB approval was not required. Average age at death was 57.0 years ±6.2 years. There were 211 (92%) male specimens and 176 (77%) were white. Average PI was 47.1 ± 10.5°. For PD between L3/L4, there was a relationship with PI (ß = -0.18, p = 0.008). For PD between L4/L5, there was an opposite relationship with PI (ß = 0.21, p = 0.003). Regression analyses of the interfacet to body ratio at each level found an association with PI only at L4 (p = 0.008). This study demonstrated that PI has a significant association with IFD in the lower lumbar spine. Increasing PI was associated with increased PD between L3/L4 and decreased PD between L4/L5. These results further support the close relationship between pelvic morphology and the lower lumbar spine, and suggest that L4 may have an important role in compensating for aberrant PI.