Repeatability, reproducibility and agreement of foveal avascular zone measurements using three different optical coherence tomography angiography devices.

PURPOSE: To evaluate the repeatability, the reproducibility and the agreement of foveal avascular zone (FAZ) measurements using three different optical coherence tomography angiography (OCT-A) devices. PROCEDURES: This prospective study included 24 eyes of 24 healthy volunteers. OCT-A imaging was performed using RTVue XR Avanti, Canon OCT-HS100 and Spectralis OCT-A. Repeated measurements were performed under the same conditions on two separate days, and the area of the FAZ was determined and analyzed using the above devices. RESULTS: All three devices showed a high ICC and there was no significant difference between the ICCs (pairwise comparison) of the three devices (Optovue-Canon (p = 0.66); Canon-Heidelberg (p = 0.21); Heidelberg-Optovue (p = 0.37). Agreement analysis of the three devices revealed a significant elevation of FAZ area values with the Heidelberg device and a slight underestimation of the FAZ area with the Canon device. Nevertheless, overall we found a high level of agreement between all of the three devices (ICC ≥ 0.958 (0.905-0.982)). CONCLUSIONS: Good reproducibility and repeatability were observed for all three devices. However, the agreement analysis revealed slight, but significant differences, which might limit alternating use of these devices for clinical research and follow-up examinations.

Satiety-induced enhanced neuronal activity in the frontal operculum relates to the desire for food in the obese female brain.

In the present pilot study, we questioned how eating to satiety affects cognitive influences on the desire for food and corresponding neuronal activity in the obese female brain. During EEG recording, lean (n = 10) and obese women (n = 10) self-rated the ability to reappraise visually presented food. All women were measured twice, when hungry and after eating to satiety. After eating to satiety, reappraisal of food was easier than when being hungry. Comparing the EEG data of the sated to the hungry state, we found that only in obese women the frontal operculum was involved not only in the reappraisal of food but also in admitting the desire for the same food. The right frontal operculum in the obese female brain, assumed to primarily host gustatory processes, may be involved in opposing cognitive influences on the desire for food. These findings may help to find potential brain targets for non-invasive brain stimulation or neurofeedback studies that aim at modulating the desire for food.

Quantification of macular perfusion using optical coherence tomography angiography: repeatability and impact of an eye-tracking system.

BACKGROUND: The aim of the study was to evaluate the impact of integration of the eye-tracking system (ET) on the repeatability of flow density measurements using optical coherence tomography (OCT) angiography. METHODS: 20 healthy subjects were included in this study. OCT-angiography was performed using RTVue XR Avanti (Optovue Inc., Fremont, California, USA). The macula was imaged using a 3 × 3 mm scan twice with and twice without activation of the ET. Flow density data of the macular in the superficial and deep OCT angiograms were extracted and analyzed. RESULTS: The difference between the flow density (whole en face) in the first session and second session with and without ET was statistically non-significant (with ET: superficial retinal OCT angiogram: p = 0.50; deep retinal OCT angiogram: p = 0.89; without ET: superficial retinal OCT angiogram: p = 0.81; deep retinal OCT angiogram: p = 0.24). There was no significant difference in the coefficients of repeatability for measurements with and without ET in the superficial retinal OCT angiogram (adjusted p-value = 0.176), whereas the difference was significant for the deep retinal OCT angiogram (adjusted p-value = 0.008). CONCLUSIONS: Integration of the ET improved the repeatability of flow density measurements in the deep OCT angiogram; this needs to be considered when evaluating the long-term changes of flow density and when comparing data of different studies and different devices.

Aberrant ocular architecture and function in patients with Klinefelter syndrome.

Klinefelter Syndrome (KS), the most common chromosomal disorder in men (47,XXY), is associated with numerous comorbidities. Based on a number of isolated case reports, we performed the first systematic and comprehensive evaluation of eye health in KS patients with a focus on ocular structure and vascularization. Twenty-one KS patients and 26 male and 38 female controls underwent a variety of non-invasive examinations investigating ocular morphology (examination of retinal thickness, optic nerve head, and cornea) and function (visual field testing and quantification of ocular vessel density by optical coherence tomography angiography). In comparison to healthy controls, KS patients exhibited a smaller foveal avascular zone and a decreased retinal thickness due to a drastically thinner outer nuclear layer. The cornea of KS patients showed a decreased peripheral thickness and volume. In perimetry evaluation, KS patients required brighter stimuli and gave more irregular values. KS patients show an ocular phenotype including morphological and functional features, which is very likely caused by the supernumerary X chromosome. Thus, KS should not be limited to infertility, endocrine dysfunction, neurocognitive and psychosocial comorbidities. Defining an aberrant ocular morphology and function, awareness for possible eye problems should be raised.

Quantitative analysis of retinal perfusion in mice using optical coherence tomography angiography.

PURPOSE: To evaluate repeatability of the quantitative analysis of vessel density in the retinas of healthy mice using optical coherence tomography angiography (OCT-A). METHODS: Seventeen eyes of seventeen healthy mice aged 10-15 weeks (young) and 75-95 weeks (old) were included in this study. OCT-A was performed using RTVue XR Avanti (Optovue Inc., Fremont, California, USA) under general anaesthesia. The retina was imaged twice using a 3 × 3 mm2 scan. Retinal thickness and flow density data in the superficial and deep retinal OCT angiograms were extracted and analysed. RESULTS: The differences between the flow density values (whole en face) in the first and second sessions were non-significant (superficial retinal OCT angiogram: first session: 45.4 ± 4.1% (39.1-55.3%); second session: 46.1 ± 4.7% (39.1-59.1%); p = 0.14; deep retinal OCT angiogram: first session: 47.1 ± 3.8% (39.4-53.4%); second session: 47.3 ± 3.7% (39.4-53.8%); p = 0.50). The repeatability assessment of retinal thickness yielded intraclass correlation coefficient (ICC) values ranging between (0.86-0.99) while the ICCs for the flow density measurements ranged from 0.87 to 0.92 for the superficial retinal OCT angiogram and 0.68 to 0.93 for the deep retinal OCT angiogram. CONCLUSIONS: Repeated OCT-A measurement of mice retinal vessel density (VD) revealed valid repeatability, indicating that this non-invasive technology is sufficient for longitudinal assessment of vascular changes in various mouse models and thereby opening the way to in-depth, experimental analysis of the vascular aspects of different retinal diseases and monitoring of disease progression and the effects of treatments.

Non-invasive Prefrontal/Frontal Brain Stimulation Is Not Effective in Modulating Food Reappraisal Abilities or Calorie Consumption in Obese Females.

Background/Objectives: Previous studies suggest that non-invasive transcranial direct current stimulation (tDCS) applied to the prefrontal cortex modulates food choices and calorie intake in obese humans. Participants/Methods: In the present fully randomized, placebo-controlled, within-subject and double-blinded study, we applied single sessions of anodal, cathodal, and sham tDCS to the left dorsolateral prefrontal cortex (DLPFC) and contralateral frontal operculum in 25 hungry obese women and investigated possible influences on food reappraisal abilities as well as calorie intake. We hypothesized that tDCS, (i) improves the ability to regulate the desire for visually presented foods and, (ii) reduces their consumption. Results: We could not confirm an effect of anodal or cathodal tDCS, neither on the ability to modulate the desire for visually presented foods, nor on calorie consumption. Conclusions: The present findings do not support the notion of prefrontal/frontal tDCS as a promising treatment option for obesity.

Differences in Insula and Pre-/Frontal Responses during Reappraisal of Food in Lean and Obese Humans.

Brain regions involved in the reappraisal of tasty but unhealthy foods are of special interest for the development of new therapeutic interventions for obesity, such as non-invasive brain stimulation or neurofeedback. Here, we visually presented food items (i.e., high/low caloric) to obese and lean individuals during electroencephalogram (EEG) recordings, while they either admitted or regulated their food desire. During admitting the desire for low and high calorie foods, obese as well as lean individuals showed higher activity in the left dorsolateral prefrontal cortex (DLPFC), whereas the right frontal operculum was involved in the reappraisal of the same foods, suggesting interplay between executive control and gustatory regions. Only in lean participants, we found an interaction between calorie content and the regulate/admit conditions in bilateral anterior insular cortices, suggesting that the anterior insula, assumed to primarily host gustatory processes, also underpins higher cognitive processes involved in food choices, such as evaluating the foods' calorie content for its reappraisal.

A long isoform of the epithelial sodium channel alpha subunit forms a highly active channel.

A long isoform of the human Epithelial Sodium Channel (ENaC) α subunit has been identified, but little data exist regarding the properties or regulation of channels formed by α728. The baseline whole cell conductance of oocytes expressing trimeric α728ßγ channels was 898.1±277.2 and 49.59±13.2 µS in low and high sodium solutions, respectively, and was 11 and 2 fold higher than the conductances of α669ßγ in same solutions. α728ßγ channels were also 2 to 5 fold less sensitive to activation by the serine proteases subtilisin and trypsin than α669ßγ in low and high Na+ conditions. The long isoform exhibited lower levels of full length and cleaved protein at the plasma membrane and a rightward shifted sensitivity to inhibition by increases of [Na+]i. Both channels displayed similar single channel conductances of 4 pS, and both were activated to a similar extent by reducing temperature, altogether indicating that activation of baseline conductance of α728ßγ was likely mediated by enhanced channel activity or open probability. Expression of α728 in native kidneys was validated in human urinary exosomes. These data demonstrate that the long isoform of αENaC forms the structural basis of a channel with different activity and regulation, which may not be easily distinguishable in native tissue, but may underlie sodium hyperabsorption and salt sensitive differences in humans.