Comparison of macular changes according to the etiology of optic neuritis:a cross-sectional study

AIM:To compare the macular structure including foveal thickness among patients with optic neuritis(ON)according to the etiology and to investigate the possible correlation between structural and visual outcomes METHODS:In this retrospective cross-sectional study,the clinical data of patients with aquaporin-4 immunoglobulin G-related ON(AQP4 group,40 eyes),myelin oligodendrocyte glycoprotein IgG-related ON(MOG group,31 eyes),and multiple sclerosis-related ON(MS group,24 eyes)were obtained.The retinal thickness of the foveal,parafoveal and perifoveal regions were measured.Visual acuity(VA),visual field index and mean deviation were measured as visual outcomes.RESULTS:The AQP4 group showed a significantly thinner fovea(226.4±13.4μm)relative to the MOG(236.8±14.0μm,P=0.015)and MS(238.9±14.3μm,P=0.007)groups.The thickness in the parafoveal area also was thinner in the AQP4 group,though the difference in perifoveal retinal thickness was not significant.Foveal thickness was correlated with VA in the AQP4 group(coefficientρ=-0.418,P=0.014),but not in the MOG and MS groups(P=0.218 and P=0.138,respectively).There was no significant correlation between foveal thickness and visual field test in all three groups.CONCLUSION:The significant thinning in the fovea and parafoveal areas in the AQP4 group compared to the MOG and MS groups are found.Additionally,macular changes in AQP4-ON show a significant correlation with VA.The results provide the possibility that retinal structural damage could reflect functional damage in AQP4-ON,distinct from MOGON and MS-ON.

Dynamic simulation of universal spacer in Dynesys dynamic stabilization system for human vertebra

The aim of this study is to analyze the simulated behavior of universal spacer in Dynesys dynamic stabilization system inserted in human vertebra. Dynesys, so-called "Dynamic neutralization system for the spine", dynamic stabilization system is a new concept in the surgical treatment of lower back pain recently. Universal spacer used as flexible material is to stabilize the spine and the material property of universal spacer is polycarbonate urethane. Universal spacer may apply different kinematic behaviors at implanted level in vertebra. Spinal range of motion(SROM) of inter-vertebra with installed Dynesys dynamic stabilization system was studied using Adams+LifeMOD as simulation software package. The vertebra model was set up to closely resemble the in-vivo conditions. Inter-vertebra rotations were measured by post processor of Adams and compared with the intact values. SROMs of the flexion, extension, lateral bending, and axial rotation of human virtual models were measured, where three spinal fixation systems such as rigid system, Dynesys system, and fused system were installed. As a result, the value of SROM is decreased in flexion-extension and lateral bending when the spinal fixation system is implanted. The movement of Dynesys system is similar to that of intact model by allowing the movement of lumbar. This means that the Dynesys system is proved to be safe and effective in the treatment of unstable spinal condition.

Gram-negative bacteria and their lipopolysaccharides in Alzheimer’s disease:pathologic roles and therapeutic implications

Alzheimer's disease(AD)is the most serious age-related neurodegenerative disease and causes destructive and irreversible cognitive decline.Failures in the development of therapeutics targeting amyloid-β(Aβ)and tau;principal proteins inducing pathology in AD,suggest a paradigm shift towards the development of new therapeutic targets.The gram-negative bacteria and lipopolysaccharides(LPS)are attractive new targets for AD treatment.Surprisingly,an altered distribution of gram-negative bacteria and their LPS has been reported in AD patients.Moreover,gram-negative bacteria and their LPS have been shown to affect a variety of AD-related pathologies,such as Aβ homeostasis,tau pathology,neuroinflammation,and neurodegeneration.Moreover,therapeutic approaches targeting gram-negative bacteria or gram-negative bacterial molecules have significantly alleviated AD-related pathology and cognitive dysfunction.Despite multiple evidence showing that the gram-negative bacteria and their LPS play a crucial role in AD pathogenesis,the pathogenic mechanisms of gram-negative bacteria and their LPS have not been clarified.Here,we summarize the roles and pathomechanisms of gram-negative bacteria and LPS in AD.Furthermore,we discuss the possibility of using gram-negative bacteria and gram-negative bacterial molecules as novel therapeutic targets and new pathological characteristics for AD.

Early bifurcation of hepatic artery in right-sided living-donor hepatectomy at Asan Medical Center: rarely a critical issue

In living donor liver transplantation(LDLT),early bifurcation of hepatic artery(HA)relative to the cutting line of bile duct(BD)requires additional skeletonization of the hilar plate,especially around BD,compared to opposite condition.Subsequently,it may preclude higher chances of biliary complications such as bile leak and biliary stenosis in the donor.Hence,donor surgeons should be well aware of the anatomical correlations among HA,BD,and portal vein(PV),based on preoperative 3-dimensional(3D)images,and also intraoperatively perform meticulous dissection of HA from the surrounding tissues and minimize the damage of microcirculation to the BD without using energy devices such as electrocautery(1).When extensive dissection around BD&its ischemic damage in the donor is expected to obtain single HA opening of the harvesting graft,we prefer separate two HA openings including right anterior and posterior HAs to single right HA(RHA)opening without skeletonization of donor’s BD.