Motion Information via the Nonfixating Eye Can Drive Optokinetic Nystagmus in Strabismus

Purpose: Strabismic patients can perceptually suppress information from one eye to avoid double vision. However, evidence from prior studies shows that some parts of the visual field of the deviated eye are not suppressed. Our goal here was to investigate whether motion information available only to the deviated eye can be utilized by the oculomotor system to drive eye movements. Methods: Binocular eye movements were acquired in two exotropic monkeys in a dichoptic viewing task in which the fixating eye viewed a stationary spot and the deviated eye viewed a 10° × 10° stationary patch that contained a drifting grating stimulus moving at 10°/s to the right or left for 20 seconds. Spatial location and contrast of the grating were systematically varied in subsequent trials. For each trial, mean slow-phase velocity of the optokinetic nystagmus (OKN) elicited by grating motion was calculated. Results: We found that OKN responses can be elicited by a motion stimulus presented to the foveal region of the deviated eye. Optokinetic nystagmus magnitude varied depending on which eye was viewing the drifting grating and correlated well with fixation preference and fixation stability (indicators of amblyopia). The magnitude of OKN increased for increased relative contrast of the motion stimulus compared to the fixation spot. Conclusions: Our results show that motion information available only to the deviated eye can drive optokinetic eye movements. We conclude that the brain has access to visual information from portions of the deviated eye (including the fovea) in strabismus that it can use to drive eye movements

Brief ampelographic characterization of indigenous grapevine cultivars subjected to clonal selection in Turkey

A unique national clonal selection programme is still being conducted on 24 indigenous table (15 white, 6 black, 3 red), 16 wine (7 white, 9 red) and 4 raisin (2 white seedless, 2 white seeded) grape cultivars in 9 agricultural regions of Turkey. As the results of this programme, 127 candidate clones belonging to 13 cultivars have been selected This paper also includes a brief ampelographic description of the indigenous Turkish grape cultivars subjected to clonal selection, based mainly on fruit characteristics, growth, productivity and ripening periods in their primary locations

Comparison of Naso-temporal Asymmetry During Monocular Smooth Pursuit, Optokinetic Nystagmus, and Ocular Following Response in Strabismic Monkeys

Purpose: Under monocular viewing conditions, humans and monkeys with infantile strabismus exhibit asymmetric naso-temporal (N-T) responses to motion stimuli. The goal of this study was to compare and contrast these N-T asymmetries during 3 visually mediated eye tracking tasks-optokinetic nystagmus (OKN), smooth pursuit (SP) response, and ocular following responses (OFR). Methods: Two adult strabismic monkeys were tested under monocular viewing conditions during OKN, SP, or OFR stimulation. OKN stimulus was unidirectional motion of a 30°x30° random dot pattern at 20°, 40°, or 80°/s for 1 minute. OFR stimulus was brief (200 ms) unidirectional motion of a 38°x28°whitenoise at 20°, 40°, or 80°/s. SP stimulus consisted of foveal step-ramp target motion at 10°, 20°, or 40°/s. Results: Mean nasalward steady state gain (0.87±0.16) was larger than temporalward gain (0.67±0.19) during monocular OKN (P<0.001). In monocular OFR, the asymmetry is manifested as a difference in OFR velocity gain (nasalward: 0.33±0.19, temporalward: 0.22±0.12; P=0.007). During monocular SP, mean nasal gain (0.97±0.2) was larger than temporal gain (0.66±0.14; P<0.001) and the mean nasalward acceleration during pursuit initiation (156±61°/s2) was larger than temporalward acceleration (118±77°/s2; P=0.04). Comparison of N-T asymmetry ratio across the 3 conditions using ANOVA showed no significant difference. Conclusion: N-T asymmetries are identified in all 3 visual tracking paradigms in both monkeys with either eye viewing. Our data are consistent with the current hypothesis for the mechanism for N-T asymmetry that invokes an imbalance in cortical drive to brainstem circuits

Spatial Patterns of Fixation-Switch Behavior in Strabismic Monkeys

Purpose: Patients with strabismus perceptually suppress information from one eye to avoid double vision. Mechanisms of visual suppression likely lead to fixation-switch behavior wherein the subject acquires targets with a specific eye depending on target location in space. The purpose of this study was to investigate spatial patterns of fixation-switch behavior in strabismic monkeys. Methods: Eye movements were acquired in three exotropic and one esotropic monkey in a binocular viewing saccade task. Spatial patterns of fixation were analyzed by calculating incidence of using either eye to fixate targets presented at various gaze locations. Results: Broadly, spatial fixation patterns and fixation-switch behavior followed expectations if a portion of the temporal retina was suppressed in exotropia and a portion of the nasal retina was suppressed in esotropia. Fixation-switch occurred for horizontal target locations that were approximately greater than halfway between the lines of sight of the foveating and strabismic eyes. Surprisingly, the border between right eye and left eye fixation zones was not sharply defined and there was a significant extent (>10°) over which the monkeys could acquire a target with either eye. Conclusions: We propose that spatial fixation patterns in strabismus can be accounted for in a decision framework wherein the oculomotor system has access to retinal error information from each eye and the brain chooses between them to prepare a saccade. For target locations approximately midway between the two foveae, strength of retinal error representations from each eye is almost equal, leading to trial-to-trial variability in choice of fixating eye

The reference frame for encoding and retention of motion depends on stimulus set size

YesThe goal of this study was to investigate the reference frames used in perceptual encoding and storage of visual motion information. In our experiments, observers viewed multiple moving objects and reported the direction of motion of a randomly selected item. Using a vector-decomposition technique, we computed performance during smooth pursuit with respect to a spatiotopic (nonretinotopic) and to a retinotopic component and compared them with performance during fixation, which served as the baseline. For the stimulus encoding stage, which precedes memory, we found that the reference frame depends on the stimulus set size. For a single moving target, the spatiotopic reference frame had the most significant contribution with some additional contribution from the retinotopic reference frame. When the number of items increased (Set Sizes 3 to 7), the spatiotopic reference frame was able to account for the performance. Finally, when the number of items became larger than 7, the distinction between reference frames vanished. We interpret this finding as a switch to a more abstract nonmetric encoding of motion direction. We found that the retinotopic reference frame was not used in memory. Taken together with other studies, our results suggest that, whereas a retinotopic reference frame may be employed for controlling eye movements, perception and memory use primarily nonretinotopic reference frames. Furthermore, the use of nonretinotopic reference frames appears to be capacity limited. In the case of complex stimuli, the visual system may use perceptual grouping in order to simplify the complexity of stimuli or resort to a nonmetric abstract coding of motion information

Predictive model of biliocystic communication in liver hydatid cysts using classification and regression tree analysis

<p>Abstract</p> <p>Background</p> <p>Incidence of liver hydatid cyst (LHC) rupture ranged 15%-40% of all cases and most of them concern the bile duct tree. Patients with biliocystic communication (BCC) had specific clinic and therapeutic aspect. The purpose of this study was to determine witch patients with LHC may develop BCC using classification and regression tree (CART) analysis</p> <p>Methods</p> <p>A retrospective study of 672 patients with liver hydatid cyst treated at the surgery department "A" at Ibn Sina University Hospital, Rabat Morocco. Four-teen risk factors for BCC occurrence were entered into CART analysis to build an algorithm that can predict at the best way the occurrence of BCC.</p> <p>Results</p> <p><b>I</b>ncidence of BCC was 24.5%. Subgroups with high risk were patients with jaundice and thick pericyst risk at 73.2% and patients with thick pericyst, with no jaundice 36.5 years and younger with no past history of LHC risk at 40.5%. Our developed CART model has sensitivity at 39.6%, specificity at 93.3%, positive predictive value at 65.6%, a negative predictive value at 82.6% and accuracy of good classification at 80.1%. Discriminating ability of the model was good 82%.</p> <p>Conclusion</p> <p>we developed a simple classification tool to identify LHC patients with high risk BCC during a routine clinic visit (only on clinical history and examination followed by an ultrasonography). Predictive factors were based on pericyst aspect, jaundice, age, past history of liver hydatidosis and morphological Gharbi cyst aspect. We think that this classification can be useful with efficacy to direct patients at appropriated medical struct's.</p

Detection of circulating miRNAs : comparative analysis of extracellular vesicle-incorporated miRNAs and cell-free miRNAs in whole plasma of prostate cancer patients

Funding Information: This study was supported by the Norwegian Financial Mechanism 2009–2014 under Project Contract No NFI/R/2014/045. The funding body had no role in the design of the study and collection, analysis, and interpretation of data and in writing the manuscript. Publisher Copyright: © 2017 The Author(s).Background: Circulating cell-free miRNAs have emerged as promising minimally-invasive biomarkers for early detection, prognosis and monitoring of cancer. They can exist in the bloodstream incorporated into extracellular vesicles (EVs) and ribonucleoprotein complexes. However, it is still debated if EVs contain biologically meaningful amounts of miRNAs and may provide a better source of miRNA biomarkers than whole plasma. The aim of this study was to systematically compare the diagnostic potential of prostate cancer-associated miRNAs in whole plasma and in plasma EVs. Methods: RNA was isolated from whole plasma and plasma EV samples from a well characterised cohort of 50 patient with prostate cancer (PC) and 22 patients with benign prostatic hyperplasia (BPH). Nine miRNAs known to have a diagnostic potential for PC in cell-free blood were quantified by RT-qPCR and the relative quantities were compared between patients with PC and BPH and between PC patients with Gleason score ≥ 8 and ≤6. Results: Only a small fraction of the total cell-free miRNA was recovered from the plasma EVs, however the EV-incorporated and whole plasma cell-free miRNA profiles were clearly different. Four of the miRNAs analysed showed a diagnostic potential in our patient cohort. MiR-375 could differentiate between PC and BPH patients when analysed in the whole plasma, while miR-200c-3p and miR-21-5p performed better when analysed in plasma EVs. EV-incorporated but not whole plasma Let-7a-5p level could distinguish PC patients with Gleason score ≥ 8 vs ≤6. Conclusions: This study demonstrates that for some miRNA biomarkers EVs provide a more consistent source of RNA than whole plasma, while other miRNAs show better diagnostic performance when tested in the whole plasma.publishersversionPeer reviewe

Variations in seasonal solar insolation are associated with a history of suicide attempts in bipolar I disorder

Background: Bipolar disorder is associated with circadian disruption and a high risk of suicidal behavior. In a previous exploratory study of patients with bipolar I disorder, we found that a history of suicide attempts was associated with differences between winter and summer levels of solar insolation. The purpose of this study was to confirm this finding using international data from 42% more collection sites and 25% more countries. Methods: Data analyzed were from 71 prior and new collection sites in 40 countries at a wide range of latitudes. The analysis included 4876 patients with bipolar I disorder, 45% more data than previously analyzed. Of the patients, 1496 (30.7%) had a history of suicide attempt. Solar insolation data, the amount of the sun’s electromagnetic energy striking the surface of the earth, was obtained for each onset location (479 locations in 64 countries). Results: This analysis confirmed the results of the exploratory study with the same best model and slightly better statistical significance. There was a significant inverse association between a history of suicide attempts and the ratio of mean winter insolation to mean summer insolation (mean winter insolation/mean summer insolation). This ratio is largest near the equator which has little change in solar insolation over the year, and smallest near the poles where the winter insolation is very small compared to the summer insolation. Other variables in the model associated with an increased risk of suicide attempts were a history of alcohol or substance abuse, female gender, and younger birth cohort. The winter/summer insolation ratio was also replaced with the ratio of minimum mean monthly insolation to the maximum mean monthly insolation to accommodate insolation patterns in the tropics, and nearly identical results were found. All estimated coefficients were significant at p &lt; 0.01. Conclusion: A large change in solar insolation, both between winter and summer and between the minimum and maximum monthly values, may increase the risk of suicide attempts in bipolar I disorder. With frequent circadian rhythm dysfunction and suicidal behavior in bipolar disorder, greater understanding of the optimal roles of daylight and electric lighting in circadian entrainment is needed

Exploratory study of ultraviolet B (UVB) radiation and age of onset of bipolar disorder

Background: Sunlight contains ultraviolet B (UVB) radiation that triggers the production of vitamin D by skin. Vitamin D has widespread effects on brain function in both developing and adult brains. However, many people live at latitudes (about &gt; 40 N or S) that do not receive enough UVB in winter to produce vitamin D. This exploratory study investigated the association between the age of onset of bipolar I disorder and the threshold for UVB sufficient for vitamin D production in a large global sample. Methods: Data for 6972 patients with bipolar I disorder were obtained at 75 collection sites in 41 countries in both hemispheres. The best model to assess the relation between the threshold for UVB sufficient for vitamin D production and age of onset included 1 or more months below the threshold, family history of mood disorders, and birth cohort. All coefficients estimated at P ≤ 0.001. Results: The 6972 patients had an onset in 582 locations in 70 countries, with a mean age of onset of 25.6&nbsp;years. Of the onset locations, 34.0% had at least 1&nbsp;month below the threshold for UVB sufficient for vitamin D production. The age of onset at locations with 1 or more months of less than or equal to the threshold for UVB was 1.66&nbsp;years younger. Conclusion: UVB and vitamin D may have an important influence on the development of bipolar disorder. Study limitations included a lack of data on patient vitamin D levels, lifestyles, or supplement use. More study of the impacts of UVB and vitamin D in bipolar disorder is needed to evaluate this supposition