La prematuridad: un antecedente de obligada consideración a la hora de valorar el complejo de células ganglionares de la retina

IntroductionPremature children birth and survival is becoming more frequent due to the improvement in obstetric and neonatal care. This makes it increasingly common to find patients with history of preterm birth in ophthalmology clinics, both in pediatric and adult ages. Premature birth can lead to ocular structural changes, being possible to affect the ganglion cell complex (GCC), among other structures, which can be studied using optical coherence tomography.Materials and methodsTo carry out a bibliographic review of the studies that analyze GCC in patients with a history of prematurity compared with patients born at term.ResultsSeveral studies that analyze GCC in patients with a history of prematurity are referenced and their results are studied.ConclusionsIn our clinical practice, knowing the history of prematurity is fundamental in the assessment of GCC measured by optical coherence tomography, since this layer is different in the patients with a history of prematurity compared to patients born at term.     

Electronic measurement of plantar contact area during walking using an adaptive thresholding method for Medilogic® pressure-measuring insoles

BackgroundPressure-measuring insoles have the potential to measure plantar contact area (PA) during walking. However, they are not widely used for this purpose because of the need for a reliable process that can convert the insole output into PA. The purposes of this study were to: (1) develop an adaptive-threshold method for pressure-measuring insoles that can improve the accuracy of the PA measurements during walking, and (2) experimentally assess the accuracy and generalizability of this method.MethodsA sample of 42 healthy, ambulatory, young adults (age = 24.3 ± 3.2 years, mass = 67.2 ± 16.9 kg, height = 1.63 ± 0.08 m) completed 10 trials walking on an elevated walkway while wearing Medilogic^® pressure-measuring insoles (sizes 35–45). A total of six insole sizes were considered. Insole data were converted to PA using three unique adaptive-thresholds that were based on percentages of the maximum sum of digital values (MSDV) during an analyzed step. Three values were considered: 0.1%, 0.2%, and 0.3% of the MSDV. Additionally, a fixed-threshold, which is typically used to estimate PA, was assessed. These two techniques, applied to the insole worn on the left foot, were compared with PA obtained from high-resolution reference footprints obtained from optical pedography of the right foot and processed using digital image processing algorithms. An assumption of PA symmetry between the left (insole) and right (barefoot) feet was made and comparisons were conducted over the entire stance phase of walking. The generalizability of the algorithm was assessed by comparing PA errors from insoles with respect to the optical pedography results based on insole size criteria.ResultsThe adaptive-thresholds of 0.1%, 0.2%, and 0.3% of MSDV produced mean errors of 7.31 ± 17.44%, −8.62 ± 15.01%, and −20.45 ± 14.18%, respectively. Using the 2-digital value fixed-threshold produced a mean error of 20.88 ± 22.44%. The best performing adaptive-threshold varied among insole sizes.ConclusionIt was observed that the fixed-threshold technique produced large magnitudes of errors. The proposed adaptive-thresholds of 0.1% and 0.2% of the MSDV reduced PA error to ±10% during walking. The adaptive-threshold method consistently reduced PA error vs. the fixed-threshold for each insole size.     

Optical coherence tomography (OCT) study in Argentinean Huntington’s disease patients

Abstract

Background: Huntington’s disease (HD) is a genetic, rare and progressive neurodegenerative disorder that causes motor and cognitive impairment in midlife patients. Although retinal damage was observed in animal HD models and in patients with other neurodegenerative diseases, we still need confirmation of impairment in HD patients. Optical coherence tomography (OCT) is a non-invasive methodology that analyses the retinal nerve fibre layers (RNFL) and could reflect processes of neurodegeneration.

Methods: A cross-sectional study with 14?HD patients who underwent a spectral domain OCT. Results were compared with a control group. Demographic data were also obtained.

Results: Temporal and superior RNFL sectors in HD showed a significant RNFL thinning compared with a control group. However, no differences were identified in mean total RNFL thickness between HD patients and controls.

Conclusions: OCT is a rapid and non-invasive technique that can be investigated in larger cohorts of patients to assess its potential role as a biomarker in HD patients.     

Comparison of the Clinical Manifestations between Acute Vogt-Koyanagi-Harada Disease and Acute Bilateral Central Serous Chorioretinopathy

PurposeTo compare clinical, angiographic, and optical coherence tomographic characteristics between eyes with acute Vogt-Koyanagi-Harada (VKH) disease and eyes with acute bilateral central serous chorioretinopathy (CSC), and to demonstrate distinguishing features between the two diseases in confusing cases.MethodsThe medical records of 35 patients with VKH disease and 25 patients with bilateral CSC were retrospectively reviewed. Characteristics according to slit-lamp biomicroscopy, ophthalmoscopy, fundus photography, fluorescein angiography, indocyanine green angiography, and spectral-domain optical coherence tomography were compared between the two diseases.ResultsFive of 35 patients (10 of 70 eyes, 14.3%) with VKH disease were initially misdiagnosed as CSC patients, and six of 25 patients (12 of 50 eyes, 24%) with bilateral CSC were initially misdiagnosed as patients with VKH disease. Pigment epithelial detachment in CSC and optic disc hyperemia in VKH disease show the highest positive predictive values of 100% for each disease.ConclusionsOptic disc hyperemia in VKH disease and pigment epithelial detachment in bilateral CSC are the most specific clinical manifestations of each disease at initial patient presentation.     

Cortical surface shift estimation using stereovision and optical flow motion tracking via projection image registration

Stereovision is an important intraoperative imaging technique that captures the exposed parenchymal surface noninvasively during open cranial surgery. Estimating cortical surface shift efficiently and accurately is critical to compensate for brain deformation in the operating room (OR). In this study, we present an automatic and robust registration technique based on optical flow (OF) motion tracking to compensate for cortical surface displacement throughout surgery. Stereo images of the cortical surface were acquired at multiple time points after dural opening to reconstruct three-dimensional (3D) texture intensity-encoded cortical surfaces. A local coordinate system was established with its z-axis parallel to the average surface normal direction of the reconstructed cortical surface immediately after dural opening in order to produce two-dimensional (2D) projection images. A dense displacement field between the two projection images was determined directly from OF motion tracking without the need for feature identification or tracking. The starting and end points of the displacement vectors on the two cortical surfaces were then obtained following spatial mapping inversion to produce the full 3D displacement of the exposed cortical surface. We evaluated the technique with images obtained from digital phantoms and 18 surgical cases – 10 of which involved independent measurements of feature locations acquired with a tracked stylus for accuracy comparisons, and 8 others of which 4 involved stereo image acquisitions at three or more time points during surgery to illustrate utility throughout a procedure. Results from the digital phantom images were very accurate (0.05 pixels). In the 10 surgical cases with independently digitized point locations, the average agreement between feature coordinates derived from the cortical surface reconstructions was 1.7–2.1 mm relative to those determined with the tracked stylus probe. The agreement in feature displacement tracking was also comparable to tracked probe data (difference in displacement magnitude was <1 mm on average). The average magnitude of cortical surface displacement was 7.9 ± 5.7 mm (range 0.3–24.4 mm) in all patient cases with the displacement components along gravity being 5.2 ± 6.0 mm relative to the lateral movement of 2.4 ± 1.6 mm. Thus, our technique appears to be sufficiently accurate and computationally efficiency (typically ∼15 s), for applications in the OR.     

Optic neuritis: A mechanistic view

Acute demyelinating optic neuritis is a condition of the optic nerves characterized by inflammation, demyelination, and neurodegeneration. Optic neuritis is a relatively common demyelinating event, strongly associated with multiple sclerosis. A number of clinical, radiographic, retinal imaging, and electrophysiologic techniques have provided significant insight into the pathologic and pathophysiologic mechanisms of optic neuritis and its related disorder multiple sclerosis. The development of validated biomarkers within the anterior visual system has paved the way for novel investigations aimed at characterizing the processes of axonal loss and neurodegeneration, neuroprotection, and perhaps even neurorestoration strategies.     

Molecular interaction of imino sugars with human α-galactosidase: Insight into the mechanism of complex formation and pharmacological chaperone action in Fabry disease

Enzyme enhancement therapy (EET) for Fabry disease involving imino sugars has been developed and attracted interest. It is thought that imino sugars act as pharmacological chaperones for wild-type and mutant α-galactosidases (GLAs) in cells, but the mechanisms underlying the molecular interactions between the imino sugars and the enzyme have not been clarified yet. We examined various kinds of imino sugars and found that galactostatin bisulfite (GBS) inhibited GLA in vitro and increased the enzyme activity in cultured Fabry fibroblasts as in the case of 1-deoxygalactonojirimycin (DGJ). Then, we analyzed the molecular interactions between the imino sugars and recombinant human GLA by means of isothermal titration calorimetry and surface plasmon resonance biosensor assays, and first determined the thermodynamic and binding-kinetics parameters of imino sugar and GLA complex formation. The results revealed that DGJ bound to the enzyme more strongly than GBS, the binding of DGJ to the enzyme protein being enthalpy-driven. In the case of GBS, the reaction was mainly enthalpy-driven, but there was a possibility that entropy-driven factors were involved in the binding. Structural analysis in silico revealed that both the chemicals fit into the active-site pocket and undergo hydrogen bonding with residues comprising the active-site pocket including the catalytic ones. The side chain of GBS was oriented towards the entrance of the active-site pocket, and thus it could be in contact with residues comprising the wall of the active-site pocket. Thermodynamic, kinetic and structural studies should provide us with a lot of information for improving EET for Fabry disease.     

HPLC法测定L-(+)-扁桃酸的光学纯度

目的采用HPLC法测定L-(+)-扁桃酸的光学纯度。方法采用Chirlcel OJ-H手性色谱柱,以正己烷-乙醇-三氟乙酸(96∶4∶0.3)为流动相,检测波长220 nm,流速1.0 m L·min-1,柱温30℃。结果 L-(+)-扁桃酸与D-(-)-扁桃酸的分离良好,L-(+)-扁桃酸0.2~1.2×103μg·m L-1与峰面积的线性关系良好(r=0.9998),检测限为0.4 ng(S/N=3),定量限为1.6 ng(S/N=10)。结论所用方法快速、准确、灵敏,适于L-(+)-扁桃酸光学纯度的测定。