Accuracy of user-adjusted axial length measurements by optical biometry in eyes having combined phacovitrectomy for macular-off rhegmatogenous retinal detachment

PURPOSE: To evaluate the accuracy of user-adjusted axial length measured by optical biometry (OB) for intraocular lens (IOL) power calculations in eyes having combined phacovitrectomy for macula-off rhegmatogenous retinal detachment (RRD). SETTING: Department of Ophthalmology, Calderdale Royal Hospital, Halifax, UK. DESIGN: Prospective Retrospective case series review of 22 consecutive eyes that underwent phacovitrectomy for macula-off RRD. METHODS: Axial lengths (ALs) were measured using OB with user adjustment to identify a posterior peak corresponding to the eye’s AL and ultrasound (US). These measurements were compared and analysed for accuracy to each other and the accurate indication of the eye’s AL. RESULTS: User-adjusted OB was similar to US and post-operative OB measurements. There was no statistically significant difference between the means of the AL measurements derived from user-adjusted OB and ultrasound AL (p=0.964). User-adjusted OB was not statistically significantly different to post-operative OB (p=0.242). Compared to postoperative OB, IOL power was within 0.5 Dioptre in 12 out of 13 cases (92%; 95% confidence interval (77.8%, 100.0%) for user-adjusted OB, and in only 10 out of 13 cases (77%; 95% confidence interval (54.0%, 99.8%) of US measurements. CONCLUSIONS: User-adjusted OB may be used as an alternative method for the measurement of AL in macula-off RRD for primary repair by combined phacovitrectomy. OB will, however, require assessment of agreement with US AL in cases where a posterior peak is not easily identifiable. We have also shown that user-adjusted OB may outperform US AL when calculating IOL power; however, a larger study may be needed to confirm thi

A quantitative LC-MS/MS method for analysis of mitochondrial -specific oxysterol metabolism

Oxysterols are critical regulators of inflammation and cholesterol metabolism in cells. They are oxidation products of cholesterol and may be differentially metabolised in subcellular compartments and in biological fluids. New analytical methods are needed to improve our understanding of oxysterol trafficking and the molecular interplay between the cellular compartments required to maintain cholesterol/oxysterol homeostasis. Here we describe a method for isolation of oxysterols using solid phase extraction and quantification by liquid chromatography-mass spectrometry, applied to tissue, cells and mitochondria. We analysed five monohydroxysterols; 24(S)-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, 7α-hydroxycholesterol, 7 ketocholesterol and three dihydroxysterols 7α-24(S)dihydroxycholesterol, 7α-25dihydroxycholesterol, 7α-27dihydroxycholesterol by LC-MS/MS following reverse phase chromatography. Our new method, using Triton and DMSO extraction, shows improved extraction efficiency and recovery of oxysterols from cellular matrix. We validated our method by reproducibly measuring oxysterols in mouse brain tissue and showed that mice fed a high fat diet had significantly lower levels of 24S/25diOHC, 27diOHC and 7ketoOHC. We measured oxysterols in mitochondria from peripheral blood mononuclear cells and highlight the importance of rapid cell isolation to minimise effects of handling and storage conditions on oxysterol composition in clinical samples. In addition, in vitro cell culture systems, of THP-1 monocytes and neuronal-like SH-SH5Y cells, showed mitochondrial-specific oxysterol metabolism and profiles were lineage specific. In summary, we describe a robust and reproducible method validated for improved recovery, quantitative linearity and detection, reproducibility and selectivity for cellular oxysterol analysis. This method enables subcellular oxysterol metabolism to be monitored and is versatile in its application to various biological and clinical samples

Accuracy of Intraocular Lens Power Estimation in Eyes Having Phacovitrectomy for Rhegmatogenous Retinal Detachment

Purpose: To evaluate the accuracy of intraocular lens power estimation in eyes having phacovitrectomy for rhegmatogenous retinal detachment. Methods: Retrospective case review of 100 consecutive eyes that underwent phacovitrectomy for rhegmatogenous retinal detachment. Axial lengths were measured using optical biometry and/or ultrasound A-scan. Achieved and predicted refraction were compared to calculate the mean postoperative refractive prediction error and the mean absolute prediction error. Factorial analysis of variance models were developed to assess outcome on the whole and that between the subgroups. Results: Ninety-five eyes had postoperative refraction: 41 macula-on (43%) and 54 macula-off (57%). The mean postoperative prediction error was -0.34 +/- 0.89 diopters. There was no statistical significant difference in the refractive outcomes between macula-on and macula-off groups (P > 0.05). Overall, using mean absolute prediction error as the outcome measure, optical biometry was more accurate than ultrasound (P = 0.040). However, significantly more ultrasound-measured axial lengths were selected for intraocular lens power estimation in macula-off group compared with the macula-on group (P = 0.016). Conclusion: Combined phacovitrectomy in rhegmatogenous retinal detachment included a small biometric error that was within the tolerable range in most cases. Both optical biometry and ultrasound should be used to estimate axial lengths, for macula-off rhegmatogenous retinal detachment cases, to improve the accuracy of intraocular lens power calculation

Mitochondrial lipid trafficking

Mitochondria are dynamic organelles surrounded by two membranes with a defined lipid composition. The majority of lipids are synthesized in the endoplasmic reticulum (ER) and transported to the mitochondria, but the synthesis of cardiolipin and phosphatidylethanolamine in the inner membrane of mitochondria highlights their general importance for cellular lipid metabolism. Extensive exchange of lipids and their precursors occurs between the ER and mitochondria as well as between mitochondrial membranes. The recent identification of membrane-tethering complexes and lipid-transfer proteins in mitochondria now provides the first insight into the mechanisms of these transport processes, which are of fundamental importance for mitochondrial activities and cell homeostasis. Here, we summarize the current understanding of lipid trafficking at the mitochondria and discuss emerging models for the mechanisms of lipid transfer

Mitochondrial lipid trafficking

Mitochondria are dynamic organelles surrounded by two membranes with a defined lipid composition. The majority of lipids are synthesized in the endoplasmic reticulum (ER) and transported to the mitochondria, but the synthesis of cardiolipin and phosphatidylethanolamine in the inner membrane of mitochondria highlights their general importance for cellular lipid metabolism. Extensive exchange of lipids and their precursors occurs between the ER and mitochondria as well as between mitochondria! membranes. The recent identification of membrane-tethering complexes and lipid-transfer proteins in mitochondria now provides the first insight into the mechanisms of these transport processes, which are of fundamental importance for mitochondrial activities and cell homeostasis. Here, we summarize the current understanding of lipid trafficking at the mitochondria and discuss emerging models for the mechanisms of lipid transfer

Mitochondrial lipid transport at a glance

Lipids are the building blocks of cellular membranes and are synthesized at distinct parts of the cell. A precise control of lipid synthesis and distribution is crucial for cell function and survival. The endoplasmic reticulum (ER) is the major lipidsynthesizing organelle. However, a subset of lipids is synthesized within mitochondria, and this aspect has become a focus of recent lipid research. Mitochondria form a dynamic membrane network that is reshaped by fusion and fission events. Their functionality therefore depends on a continuous lipid supply from the ER and the distribution of lipids between both mitochondrial membranes. The mechanisms of mitochondrial lipid trafficking are only now emerging and appear to involve membrane contact sites and lipid transfer proteins. In this Cell Science at a Glance article, we will discuss recent discoveries in the field of mitochondrial lipid trafficking that build on long-standing observations and shed new light on the shuttling of membrane lipids between mitochondria and other organelles