[On the transformation of evoked potentials of the rabbit visual cortex into a discharge of the spike-wave type].
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Animals↗
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Homogeneity and diversity of color-opponent horizontal cells in the turtle retina: Consequences for potential wavelength discrimination.
Color information processing in fish and turtles starts with the transformation of the tetra-chromatic cone system into two types of color-opponent horizontal cells (C-type). Few studies reported on large variability between C-type horizontal cells of the same class, suggesting it might improve color vision. However, such variability is contradictory with the tight coupling between horizontal cells that tends to average intercellular differences. We addressed this apparent discrepancy, and studied the spectral properties of C-type horizontal cells in the turtle retina. Photoresponses were recorded in the eyecup preparation, using light stimuli of different wavelengths and intensities. The spectral properties of each cell were defined by the neutral points (wavelengths at which response polarity reversed), which were derived from sensitivity data and from large-amplitude photoresponses. For each C-type horizontal cell, a linear relationship between log stimulus intensity needed for polarity reversal and wavelength was found. With this definition, homologous C-type horizontal cells from the same retina were practically identical in their spectral properties, indicating that the averaging effects of the horizontal cell syncytium eliminated any intercellular variability. In contrast, C-type horizontal cells of the same class exhibited large inter-retina variability. We tested the potential for wavelength discrimination by applying the line element theory to the action spectra of the two chromatic (Red/Green & Yellow/Blue) horizontal cell channels, and found good agreement with behavioral data from a similar species of turtles.
Animals↗
[For a history of the present of playing and health practices].
The purpose of this study is to reflect on the need to perform a historical-discursive approach to contextualize and analyze in a critical way hospital and nursing discourses and practices related to spaces to play in pediatric infirmaries at hospitals. The Statute of the Children and Adolescents, made into a Federal Law in 1990, is a document that guides a new vision concerning the field of childhood and youth. Among the consequences of the ECA, there is the establishment of a different mode for the adult to relate with children, and that the effects on healthcare should assume and effect changes and transformations in the hospital scenario. We have tried to show the need to problematize and contextualize how our hospital scenario is determined by discourses that operate silently. In order to resist to the effects of such devices, health and nursing practices should be rethought and rectified in their respective disciplinary devices.
Child↗
Primary brain tumors: review of etiology, diagnosis and treatment.
The activation of oncogenes and the inactivation of tumor suppressor genes within neoplastic cells lead to transformation and loss of growth control. The key clinical feature that should arouse suspicion of a primary brain tumor and lead to a prompt evaluation is the progressive nature of the signs and symptoms, which include headaches, nausea and emesis, double vision, change in personality or cognition, speech difficulty, seizures and weakness. Neuroimaging with contrast-enhanced computed tomography or magnetic resonance imaging is the best method of confirming the presence of a primary brain tumor. Initial treatment in most patients is biopsy or surgical resection. For malignant and selected benign primary brain tumors, further treatment is necessary and may include radiation therapy, chemotherapy or experimental protocols.
Adult↗
Defects in courtship and vision caused by amino acid substitutions in a putative RNA-binding protein encoded by the no-on-transient A (nonA) gene of Drosophila.
The Drosophila no-on-transient A (nonA) gene is involved in the visual behaviors and courtship song of the fly. The NONA polypeptide contains two copies of the RNA-recognition motif (RRM), a hallmark of proteins involved in RNA binding, and an adjacent conserved charged region. This 311-amino-acid region is found in four other proteins and largely overlaps the Drosophila-Behavior/Human Splicing (or DBHS) domain. The newest family member, Drosophila nAhomo, was discovered in a database search, and encodes a protein with 80% identity to NONA. In this study, three nonA mutations generated by chemical mutagenesis were sequenced and found to fall within the conserved region. Site-directed mutagenesis of the two RRMs, and within a (conserved) charged region located C-terminal to them, was performed to determine the significance of these domains with respect to whole-organismal phenotypes. Behavior and viability were assessed in transformed flies, the genetic background of which lacks the nonA locus. Point mutations of amino acid 548 in the charged region confirmed the etiology of the nonAdiss courtship-song mutation and showed that a milder substitution at this site produced intermediate singing behavior, although it failed to rescue visual defects. Mutagenesis of the RRM1 domain resulted in effects on viability, vision, and courtship song. However, amino acid substitutions in RNP-II of RRM2 led to near-normal phenotypes, and the in vivo nonA mutations located in or near RRM2 caused visual defects only. Thus, we suggest that the first RRM could be important for all functions influenced by nonA, whereas the second RRM may be required primarily for normal vision.
Amino Acid Sequence↗
[Comparison of objective assessment using the sweep pattern visual evoked response acuity (SPVERA) and illiterate E visual acuity].
OBJECTIVE: To compare the vision objectively assessed by SPVERA with the illiterate E Acuity in normal subjects. METHODS: The effect of artificially induced image defocusing on visual acuities (Vas) measured by SPVEP and illiterate E chart measurement was studied in 14 normal subjects. SPVEP was recorded using vertical gratings of 8 different spatial frequencies ranging from 0.235 9 to 30.203 2 c/deg. The responses were averaged and displayed through the discrete Fourier transform on the monitor display. SPVERA was determined by extrapolating the PVER amplitude -spatial frequency function to baseline. SPVERA was compared with illiterate E visual acuity measured under the same conditions of optical defocus. RESULTS: With moderate defocusing (<+1.0 diopter (D),VA > 0.42), the SPVERA were equal to or poorer than the illiterate E visual acuity. With more defocus (> +2.0 diopter (D), VA < 0.3),the SPVERA became better than the illiterate E chart Visual Acuity. The correlation between the two acuities was r2 = 0.919. CONCLUSION: SPVERA and the illiterate E visual acuity correlated to a certain degree. We conclude that the SPVERA is effective in estimating vision objectively.
Adult↗
Photodynamic therapy using verteporfin for choroidal neovascularization in angioid streaks.
PURPOSE: To evaluate the efficacy of photodynamic therapy with verteporfin in the management of choroidal neovascularization (CNV) associated with angioid streaks. DESIGN: Retrospective case series. METHODS: Eleven eyes of nine patients with subfoveal or juxtafoveal CNV due to angioid streaks underwent visual acuity testing, ophthalmic examination, color photography, and fluorescein angiography to evaluate the results of photodynamic therapy with verteporfin. Retreatment of persistent CNV was based on criteria from the Treatment of Age-Related Macular Degeneration with Photodynamic Therapy Investigation (TAP) except in one case. Follow-up ranged from 5 to 28 months (mean, 17 months). RESULTS: Nine of 11 eyes had subfoveal lesions while two eyes had juxtafoveal lesions on initial examination. Conversion from a choroidal neovascular membrane (CNVM) to a fibrous disciform lesion following photodynamic therapy was observed in nine eyes. Enlargement of the CNVM was noted in seven of these eyes by fluorescein angiography at final follow-up. Initial best-corrected visual acuity (BCVA) ranged from 20/25 to counting fingers (CF) (mean, 20/400; median, 20/200). Final BCVA ranged from 20/20 to CF (mean, 20/600; median, 20/400). Seven eyes with subfoveal CNVM had an initial BCVA of at least 20/200 while only three eyes maintained this level or better at last follow-up. In one patient with a juxtafoveal CNVM in one eye, vision decreased from 20/25 to 20/400 with enlargement and fibrosis of the CNVM and subfoveal extension. In the fellow eye a juxtafoveal CNVM was initially treated and then retreated earlier than TAP criteria at 6 weeks. Vision improved to 20/20 and has remained stable 5 months after the initial treatment. CONCLUSIONS: Verteporfin for choroidal neovascularization-associated with angioid streaks does not appear to significantly alter the course of this disease with most eyes undergoing enlargement and disciform transformation of the neovascular process. However, aggressive management of these patients with biomicroscopic and fluorescein angiographic examination and timely photodynamic therapy with early retreatment when indicated may be beneficial in certain cases.
Adult↗
Gaze modulation of visual aftereffects.
Physiological studies of non-human primates have suggested that the direction of gaze can modulate the gain of neuronal responses to visual stimuli in many cortical areas including V1. The neural gaze modulation is suggested to subserve the conversion from gaze-independent (eye-centered) to dependent (e.g., head-centered) representations. However, it has not been established whether the gaze modulation has significant influences on human visual perception. Here we show that gaze direction modestly but significantly modulates the magnitudes of the motion aftereffect, the tilt aftereffect and the size aftereffect. These aftereffects were stronger when the adaptation and test patterns were presented in the same gaze direction, than when they were presented in different gaze directions, even though the patterns always stimulated the same retinal location. The gaze modulation effect was not statistically significant for the post-adaptation elevation of contrast detection thresholds. The gaze modulation of visual aftereffects provides a useful psychophysical tool to analyze human cortical processes for coordinate transformations of visual space.
Figural Aftereffect↗
Making progress through molecular attacks on cancer.
The success of kinase inhibitor therapy in chronic myeloid leukemia (CML) has validated the long-held thesis in the cancer research community that a precise molecular understanding of cancer can directly affect cancer therapy. Now that several years have passed since the approval of imatinib/Gleevec for CML treatment, we have a greater appreciation for the challenges involved in effectively deploying these agents in the clinic. In this paper, I review recent events in the treatment of CML and highlight early applications of kinase inhibitor therapy to other diseases such as glioblastoma. I conclude with a vision that it may be possible, through analysis of tumor proteins secreted into serum, to track distinct molecular features of various cancers in order to select appropriate molecularly targeted therapy and measure treatment response. This new science of cancer biomarkers could radically transform the conduct of clinical trials and speed the evaluation of new molecularly targeted agents.
Biomarkers↗
Gait and Parkinson's disease: a conceptual model for an augmented-reality based therapeutic device.
This chapter presents an augmented-reality based therapeutic device designed to overcome gait problems associated with Parkinson's Disease (PD). A normal model of gait is proposed followed by a model of Parkinsonian gait with the goal of construction of a gait enabling therapeutic device. The fundamental underlying tenet of the model is that vision pathology is responsible for the majority of Parkinsonian gait pathology. The basis for such a claim is the well documented phenomenon known as Kinesia Paradoxa, whereby in the presence of certain so-called visual cues a PD subject can be transformed from a totally immobile, helpless victim of this disease into a near normal walking individual. Several gait-enabling devices are also described.
Computer Simulation↗
Quantitative features of synapse formation in the fly's visual system. I. The presynaptic photoreceptor terminal.
Photoreceptors of the adult fly's compound eye each form a population of stereotyped output synapses distributed over the surface of their terminal. The formation of this class of afferent synapses during development has been followed from serial electron microscopy of the same eye region in four pupal and several adult stages, all of female Musca domestica. These synapses, or tetrads, have an invariant postsynaptic composition of four members and so may provide a model for multiple-contact synapses in general. In the adult fly the four postsynaptic elements of each synapse are contributed by two interneurons, L1 and L2, and, usually, two alpha processes of an amacrine cell. These postsynaptic elements assemble at individual developing synapses by selective sequential addition. Assembly starts with L1 or L2, subsequent elements of the final tetrad adding in all conceivable permutations, at least as fast as one per 7 hr. They rarely (only once) incorporate incorrect or supernumerary elements, however. The synaptic population as a whole was also sampled during development to analyze the possible factors determining the normal precision of the size of the adult population. The number of synapses per terminal increases gradually until 74% pupal development. Thereafter it decreases so that the final number of synapses in each receptor's population is the consequence of a net loss. Synapses enlarge with age, chiefly by incorporating new elements, but the loss of synaptic sites is only partially offset by the increase in size of those that remain. Throughout all stages examined in pupal and adult life, total synaptic area is linearly proportional to the surface area of the axon terminal. Thus, from the 74% pupal development stage onward, a population of many small synapses closely spaced, on average, over the terminal's surface transforms into one characteristic of the adult with progressively fewer, larger, more widely spaced synapses.
Animals↗
On the role of medial geometry in human vision.
A key challenge underlying theories of vision is how the spatially restricted, retinotopically represented feature analysis can be integrated to form abstract, coordinate-free object models. A resolution likely depends on the use of intermediate-level representations which can on the one hand be populated by local features and on the other hand be used as atomic units underlying the formation of, and interaction with, object hypotheses. The precise structure of this intermediate representation derives from the varied requirements of a range of visual tasks which motivate a significant role for incorporating a geometry of visual form. The need to integrate input from features capturing surface properties such as texture, shading, motion, color, etc., as well as from features capturing surface discontinuities such as silhouettes, T-junctions, etc., implies a geometry which captures both regional and boundary aspects. Curves, as a geometric model of boundaries, have been extensively used as an intermediate representation in computational, perceptual, and physiological studies, while the use of the medial axis (MA) has been popular mainly in computer vision as a geometric region-based model of the interior of closed boundaries. We extend the traditional model of the MA to represent images, where each MA segment represents a region of the image which we call a visual fragment. We present a unified theory of perceptual grouping and object recognition where through various sequences of transformations of the MA representation, visual fragments are grouped in various configurations to form object hypotheses, and are related to stored models. The mechanisms underlying both the computation and the transformation of the MA is a lateral wave propagation model. Recent psychophysical experiments depicting contrast sensitivity map peaks at the medial axes of stimuli, and experiments on perceptual filling-in, and brightness induction and modulation, are consistent with both the use of an MA representation and a propagation-based scheme. Also, recent neurophysiological recordings in V1 correlate with the MA hypothesis and a horizontal propagation scheme. This evidence supports a geometric computational paradigm for processing sensory data where both dynamic in-plane propagation and feedforward-feedback connections play an integral role.
Contrast Sensitivity↗
An automated computer vision and robotics-based technique for 3-D flexible biomolecular docking and matching.
The generation of binding modes between two molecules, also known as molecular docking, is a key problem in rational drug design and biomolecular recognition. Docking a ligand, e.g., a drug molecule or a protein molecule, to a protein receptor, involves recognition of molecular surfaces as molecules interact at their surface. Recent studies report that the activity of many molecules induces conformational transitions by 'hinge-bending', which involves movements of relatively rigid parts with respect to each other. In ligand-receptor binding, relative rotational movements of molecular substructures about their common hinges have been observed. For automatically predicting flexible molecular interactions, we adapt a new technique developed in Computer Vision and Robotics for the efficient recognition of partially occluded articulated objects. These type of objects consist of rigid parts which are connected by rotary joints (hinges). Our approach is based on an extension and generalization of the Geometric Hashing and Generalized Hough Transform paradigm for rigid object recognition. Unlike other techniques which match each part individually, our approach exploits forcefully and efficiently enough the fact that the different rigid parts do belong to the same flexible molecule. We show experimental results obtained by an implementation of the algorithm for rigid and flexible docking. While the 'correct', crystal-bound complex is obtained with a small RMSD, additional, predictive 'high scoring' binding modes are generated as well. The diverse applications and implications of this general, powerful tool are discussed.
Algorithms↗
The programmable remapper: clinical applications for patients with field defects.
NASA, Johnson Space Center is developing an electronic image remapper which will warp an image from one coordinate system onto another with great flexibility and speed. The Programmable Remapper will transform images at conventional video frame rate. The Remapper was designed to be used in conjunction with an optical correlator to enhance object recognition through "real time" Fourier analysis. We are investigating an additional potential application for the Remapper as a low-vision aid. In diseases which result in obvious field defects such as age-related maculopathy (ARM) or retinitis pigmentosa (RP), the Remapper can be used to redistribute onto the still-functioning retina the image information that would otherwise be lost due to the associated field defect. Compared with eccentric viewing, this process makes use of the acuity of a larger area of the retina. We envision the future aid to consist of a portable spectacle-mounted display with miniaturized camera input and the Remapper. The patient will view the remapped world on this display. Patients may require training with feedback as to eye and scotoma position in order to use the Remapper most effectively. The Remapper might be reduced in cost, weight, and size to the point of being a feasible low-vision prosthesis as a result of development required by military, space, and industrial utilization. In order to demonstrate how such an aid may work, we have generated static images on an image processor which have undergone radial-only remapping; i.e., image points are slid along radii, with their azimuths unchanged. The remapping process and the application to low vision along with static images are presented in this paper.
Audiovisual Aids↗
Hospital transformation and organisational learning.
Kwong Wah Hospital was founded by the charity organisation Tung Wah Group of Hospitals some 88 years ago, with management transfer to the Hong Kong Hospital Authority in 1991. Capitalizing both from the traditional caring culture of its founder, as well as opportunities in the new management environment, the hospital has scored remarkable successes in service quality, community partnership, organisational effectiveness, and staff development. Underpinning these transformations were Structure, Process, People, and Culture strategies. The learning imperative is heavily mandated or the success of each of these strands of development. Indeed, the embodiment of a learning organisation culture provides the impetus in sustaining the change momentum, towards achieving the Vision of becoming a 'Most Preferred Hospital' in Hong Kong.
Hong Kong↗
Worldwide Innovative Network (WIN) Consortium in Personalized Cancer Medicine: Bringing next-generation precision oncology to patients.
The human genome project ushered in a genomic medicine era that was largely unimaginable three decades ago. Discoveries of druggable cancer drivers enabled biomarker-driven gene- and immune-targeted therapy and transformed cancer treatment. Minimizing treatment not expected to benefit, and toxicity-including financial and time-are important goals of modern oncology. The Worldwide Innovative Network (WIN) Consortium in Personalized Cancer Medicine founded by Drs. John Mendelsohn and Thomas Tursz provided a vision for innovation, collaboration and global impact in precision oncology. Through pursuit of transcriptomic signatures, artificial intelligence (AI) algorithms, global precision cancer medicine clinical trials and input from an international Molecular Tumor Board (MTB), WIN has led the way in demonstrating patient benefit from precision-therapeutics through N-of-1 molecularly-driven studies. WIN Next-Generation Precision Oncology (WINGPO) trials are being developed in the neoadjuvant, adjuvant or metastatic settings, incorporate real-world data, digital pathology, and advanced algorithms to guide MTB prioritization of therapy combinations for a diverse global population. WIN has pursued combinations that target multiple drivers/hallmarks of cancer in individual patients. WIN continues to be impactful through collaboration with industry, government, sponsors, funders, academic and community centers, patient advocates, and other stakeholders to tackle challenges including drug access, costs, regulatory barriers, and patient support. WIN's collaborative next generation of precision oncology trials will guide treatment selection for patients with advanced cancers through MTB and AI algorithms based on serial liquid and tissue biopsies and exploratory omics including transcriptomics, proteomics, metabolomics and functional precision medicine. Our vision is to accelerate the future of precision oncology care.
Humans↗
[Experience in 13-year follow-up of a melanocytoma of the optic nerve head].
Thirteen years ago, a 35-year-old woman was found on routine ocular examination to have a pigmented tumor in her right eye, adjacent to the optic nerve head. The appearance of her fundus was suggestive of a melanocytoma. Her visual acuities were RE: 1.0 and LE: 1.0. Ultrasound examination revealed that the tumor diameter was 4.4 mm on the base and the maximal thickness was 2.7 mm. Fluorescein angiography showed a persistent hypofluorescence of the lesion. There were several additional examinations (e.g. determination of the visual field, measurement of the intraocular pressure, detection of visually evoked potentials, CT scan and MRI examination) to exclude a benign tumor of similar appearance, The patient underwent ocular examination every year. During the observation period a minor tumor enlargement occurred but there were no changes in the visual acuities. In the last two years minor signs of malignant transformation were found. The findings documented and illustrated here suggest that our methods were useful to differentiate the melanocytoma from a malignant melanoma, and no surgical interventions were needed to characterize or to remove the tumor. In addition, our patient has had good vision during the past 13 years.
Adult↗
Moment invariants in the space and frequency domains.
Moment invariants of the Fourier transform of an image are introduced. It is found that a feature set composed of moment invariants from both the space domain and the Fourier domain gives better performance for a wide range of classification tasks than does the same number of moment invariants from either domain alone. Redundancy among moments of the two domains is examined by using the correlation coefficient between the feature kernels as a measure. Examples are used to compare the feature sets and to assess their performance in classification tasks. Moment invariants of the magnitude of the Fourier transform and, by inference, some popular features, such as the spectral ring-wedge detector, are found to fall far short in performance compared with those in which the phase of the Fourier transform is also utilized. Coherent optical systems to compute the dual-domain moment invariants are proposed.
Animals↗