Reliability of retinal vessel calibre measurements using a retinal oximeter

Background: Summarised retinal vessel diameters are linked to systemic vascular pathology. Monochromatic images provide best contrast to measure vessel calibres. However, when obtaining images with a dual wavelength oximeter the red-free image can be extracted as the green channel information only which in turn will reduce the number of photographs taken at a given time. This will reduce patient exposure to the camera flash and could provide sufficient quality images to reliably measure vessel calibres. Methods: We obtained retinal images of one eye of 45 healthy participants. Central retinal arteriolar and central retinal venular equivalents (CRAE and CRVE, respectively) were measured using semi-automated software from two monochromatic images: one taken with a red-free filter and one extracted from the green channel of a dual wavelength oximetry image. Results: Participants were aged between 21 and 62 years, all were normotensive (SBP: 115 (12) mmHg; DBP: 72 (10) mmHg) and had normal intra-ocular pressures (12 (3) mmHg). Bland-Altman analysis revealed good agreement of CRAE and CRVE as obtained from both images (mean bias CRAE = 0.88; CRVE = 2.82). Conclusions: Summarised retinal vessel calibre measurements obtained from oximetry images are in good agreement to those obtained using red-free photographs

Rationale and study design of the prospective, longitudinal, observational cohort study “rISk strAtification in end-stage renal disease” (ISAR) study

Background: The ISAR study is a prospective, longitudinal, observational cohort study to improve the cardiovascular risk stratification in endstage renal disease (ESRD). The major goal is to characterize the cardiovascular phenotype of the study subjects, namely alterations in micro-and macrocirculation and to determine autonomic function. Methods/design: We intend to recruit 500 prevalent dialysis patients in 17 centers in Munich and the surrounding area. Baseline examinations include: (1) biochemistry, (2) 24-h Holter Electrocardiography (ECG) recordings, (3) 24-h ambulatory blood pressure measurement (ABPM), (4) 24 h pulse wave analysis (PWA) and pulse wave velocity (PWV), (5) retinal vessel analysis (RVA) and (6) neurocognitive testing. After 24 months biochemistry and determination of single PWA, single PWV and neurocognitive testing are repeated. Patients will be followed up to 6 years for (1) hospitalizations, (2) cardiovascular and (3) non-cardiovascular events and (4) cardiovascular and (5) all-cause mortality. Discussion/conclusion: We aim to create a complex dataset to answer questions about the insufficiently understood pathophysiology leading to excessively high cardiovascular and non-cardiovascular mortality in dialysis patients. Finally we hope to improve cardiovascular risk stratification in comparison to the use of classical and non-classical (dialysis-associated) risk factors and other models of risk stratification in ESRD patients by building a multivariable Cox-Regression model using a combination of the parameters measured in the study

ADAPTive Informationsverarbeitung fuer die Therapieoptimierung. Teilprojekt 3: Mikrozirkulation Abschlussbericht

The scientific fundamentals were established for an individually optimized therapy of disturbed retinal microcirculation from the point of view of information therapy and metrology. In co-operation with other project groups, adaptive algorithms, formulations for solutions for Artificial Intelligence (AI) and for object oriented data banks for use on the ocular fundus were developed. These were clinico-experimentally tested on patients and test persons in the measurement systems 'Measuring Ophthalmoscope' and 'Differential Ophthalmoscope', and the applicability of the methods to other medical disciplines was studied. Thus scientific-technological prerequisites were established for on-line measurement of retinal pre- and postcapillary vessel diameter with detection limits for changes <1%, which is at present without international competition. So the individual circadian rhythms, vasomotion, pulsations and vascular reactions to stress via pressure, respiratory gas and physical exercise are significantly demonstrable. On-line measurements of the vessel diameter are also possible on the open swine brain. On a model-based measurement relation and using an adaptive measuring area, the scientific prerequisites were established for the automatic measurement of blood flow, blood velocity and vessel diameters in fluorescence angiograms. Provided sufficient picture quality, these measurements, in comparison with the present status of technology, are for the first time possible automatically, with improved reproducibility and considerably reduced systematic error. With a model of retinal microcirculation, measurements can be interpreted, and pathophysiological conditions and therapeutic effects can be simulated. With the differential ophthalmoscope, a new image generating principle for the demonstration of changes in capillary blood volume provoked by pressure was successfully presented. (orig.)SIGLEAvailable from TIB Hannover: F97B485 + a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Endoplasmic Reticulum-Derived Multilamellar Bodies in Oocytes of Mouse Follicle Cultures under Oxidized Low-Density Lipoprotein Treatment

Spanel-Borowski K, Nowicki M, Borlak J, Trapphoff T, Eichenlaub-Ritter U. Endoplasmic Reticulum-Derived Multilamellar Bodies in Oocytes of Mouse Follicle Cultures under Oxidized Low-Density Lipoprotein Treatment. Cells Tissues Organs. 2013;197(1):77-88.Objective: Multilamellar bodies associated with an organized endoplasmic reticulum (ER) arise in various somatic cell types, and a subtype called multivesicular bodies is described in oocytes. Both entities, so far undetermined in significance, may occur in oocytes of follicles under oxidative stress. In preovulatory follicles, oxidative stress appears to be caused by oxidized low-density lipoprotein (ox-LDL). Method: Cultures of preantral mouse follicles were treated with 100 mu g/ml ox-LDL or normal LDL (n-LDL) for 12-48 h or for 12 days during antral follicle growth followed by in vitro ovulation and harvest of cumulus oophorus complexes (COCs) with metaphase II (MII) oocytes on day 13. Preantral follicles, COCs, or MII oocytes were immunostained with anti-tubulin antibody or stained with actin-binding phalloidin for confocal microscopy. Ultrathin sections were prepared for electron microscopy. Results: Preantral follicles exposed to nLDL or ox-LDL developed normally, and MII oocytes in COCs possessed normal spindles with well-aligned chromosomes. In contrast, treated cumulus cells underwent apoptosis. Only the ox-LDL-treated preantral follicle oocytes showed ER-derived multilamellar bodies (EMBs) of type I, consisting of rough ER membranes for the envelope. The MII oocytes of COCs showed type II EMBs consisting of smooth/vesicular ER and were more prominent after ox-LDL than after n-LDL exposure. Degenerating mitochondria were prominent in oocytes of the ox-LDL group and judged as a sign of oxidative stress. Conclusion: Oxidative stress presumably induces damage of proteins and organelles in the oocytes. The EMBs might sequester the damaged structures for oocyte survival. Thus, EMBs could represent a novel form of autophagy. Copyright (C) 2012 S. Karger AG, Base