Changes of the peripapillary vascular parameters in premature infants without retinopathy of prematurity using U-net segmentation.

AIM: To quantitatively assess the changes in mean vascular tortuosity (mVT) and mean vascular width (mVW) around the optic disc and their correlation with gestational age (GA) and birth weight (BW) in premature infants without retinopathy of prematurity (ROP). METHODS: A single-center retrospective study included a total of 133 (133 eyes) premature infants [mean corrected gestational age (CGA) 43.6wk] without ROP as the premature group and 130 (130 eyes) CGA-matched full-term infants as the control group. The peripapillary mVT and mVW were quantitatively measured using computer-assisted techniques. RESULTS: Premature infants had significantly higher mVT (P=0.0032) and lower mVW (P=0.0086) by 2.68 (104 cm-3) and 1.85 µm, respectively. Subgroup analysis with GA showed significant differences (P=0.0244) in mVT between the early preterm and middle to late preterm groups, but the differences between mVW were not significant (P=0.6652). The results of the multiple linear regression model showed a significant negative correlation between GA and BW with mVT after adjusting sex and CGA (P=0.0211 and P=0.0006, respectively). For each day increase in GA at birth, mVT decreased by 0.1281 (104 cm-3) and for each 1 g increase in BW, mVT decreased by 0.006 (104 cm-3). However, GA (P=0.9402) and BW (P=0.7275) were not significantly correlated with mVW. CONCLUSION: Preterm birth significantly affects the peripapillary vascular parameters that indicate higher mVT and narrower mVW in premature infants without ROP. Alterations in these parameters may provide new insights into the pathogenesis of ocular vascular disease.

Oxidative stress mediated decrement of spinal endomorphin-2 contributes to lumbar disc herniation sciatica in rats.

Increasing evidence supported that oxidative stress induced by herniated lumbar disc played important role in the formation of lumbar disc herniation sciatica (LDHS), however, the neural mechanisms underlying LDHS need further clarification. Endomorphin-2 (EM2) is the endogenous ligand for mu-opioid receptor (MOR), and there is increasing evidence implicating the involvement of spinal EM2 in neuropathic pain. In this study, using an nucleus pulposus implantation induced LDHS rat model that displayed obvious mechanical allodynia, it was found that the expression of EM2 in dorsal root ganglion (DRG) and spinal cord was significantly decreased. It was further found that oxidative stress in DRG and spinal cord was significantly increased in LDHS rats, and the reduction of EM2 in DRG and spinal cord was determined by oxidative stress dominated increment of dipeptidylpeptidase IV activity. A systemic treatment with antioxidant could prevent the forming of mechanical allodynia in LDHS rats. In addition, MOR expression in DRG and spinal cord remained unchanged in LDHS rats. Intrathecal injection of MOR antagonist promoted pain behavior in LDHS rats, and the analgesic effect of intrathecal injection of EM2 was stronger than that of endomorphin-1 and morphine. Taken together, our findings suggest that oxidative stress mediated decrement of EM2 in DRG and spinal cord causes the loss of endogenous analgesic effects and enhances the pain sensation of LDHS.