Tratamento de lesões nos pés de pessoas com diabetes mellitus no cenário brasileiro: revisão integrativa

Introdução: Pessoas com diabetes mellitus são mais suscetíveis a lesões cutâneas, ulceração e infecção no pé. Essas complicações são causas frequentes de internação hospitalar e elevados custos em saúde. Objetivo: Analisar os tratamentos para o pé diabético na realidade brasileira. Método: Realizou-se revisão integrativa da literatura por meio de busca nas bases de dados  PubMed/MEDLINE, Scopus, Web of Science e EMBASE, baseada no método preconizado em seis etapas e construída conforme a metodologia PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). Dois pesquisadores independentes realizaram a combinação de descritores Diabetic foot AND Therapeutics AND Brazil, em outubro de 2020. Foram examinados artigos publicados entre 2010 e 2020. Dos artigos selecionados, extraíram-se as informações: base de dados, autor, ano de publicação, desenho de pesquisa, tratamento e principais resultados. Resultados: Dentre os 257 artigos inicialmente identificados, foram selecionados 15. A laserterapia (26,66%), seguida da oxigenoterapia hiperbárica (13,33%) foram as formas de tratamento para pé diabético mais abordadas nos estudos brasileiros. Outras terapêuticas também foram encontradas. Todas as formas de tratamento para o pé diabético mostraram efeitos positivos sobre o processo de cicatrização da ferida, reduzindo sua extensão, área de tecido desvitalizado e a dor referida. Conclusão: a terapia com laser e a oxigenoterapia hiperbárica tem sido as principais formas de tratamento testadas e implementadas na realidade brasileira por pesquisadores e profissionais de saúde

Visual dysfunction of type I and VI mucopolysaccharidosis patients evaluated with visual evoked cortical potential

Purpose: To evaluate the visual system of patients suffering from type I or VI mucopolysaccharidosis (MPS) by recording the visual evoked cortical potential (VECP). Methods: Two patients with MPS VI and 2 patients with MPS I were tested before and after enzyme replacement therapy (ERT). A control group of 20 subjects was tested for statistical comparison. VECP was elicited by monocular stimulation with 1-Hz phase-reversal checkerboard patterns at 0.5 and 2 cycles per degree and with 16° of visual field. In all patients, both eyes were tested. VECP amplitude and latency were measured and compared with tolerance limits obtained from controls. Results: MPS I and VI patients have a severe visual impairment that can be quantified by measuring VECPs. Even after several weeks of ERT, the visual impairment remained unaltered, indicating that the treatment had no significant influence on the visual conditions of MPS patients. Visual responses to high spatial frequencies were more deeply impaired than responses to low spatial frequencies. This can be explained by the kind of damage in the visual system that preferentially targets the eye optics. Conclusion: VECPs can be used to monitor the degree of visual impairment of MPS patients and to check ERT efficacy

Spatial luminance contrast sensitivity measured with transient VEP: comparison with psychophysics and evidence of multiple mechanisms. Investigative Ophthalmology and Visual

PURPOSE. To compare the spatial luminance contrast sensitivity function (CSF) obtained with transient visual evoked potentials (VEPs) with that obtained with psychophysical measurements. METHODS. The stimuli consisted of horizontal luminance gratings. In the VEP experiments, 0.4, 0.8, 2, 4, 8, and 10 cpd of spatial frequency were used, at 1 Hz square-wave contrastreversal mode. Eight to 10 Michelson contrasts were used at each spatial frequency. Contrast thresholds were estimated from extrapolation of contrast response functions. Psychophysical sensitivities were obtained with spatial gratings of 0.4, 0.8, 1, 2, 4, 6, 8, and 10 cpd and presented at 1 Hz square-wave contrast-reversal or stationary mode (dynamic and static presentation, respectively). CSF tuning was estimated by calculating the ratio between peak sensitivity and the sensitivity at 0.4 cpd. RESULTS. In all subjects tested (n ϭ 6), VEP contrast-response functions showed nonlinearities-namely, amplitude saturation and double-slope amplitude functions that occurred at low and medium-to-high spatial frequencies, respectively. Mean electrophysiological and psychophysical CSFs peaked at 2 cpd. CSF tuning for electrophysiology and dynamic and static psychophysics were, respectively, 1.08, 1.11, and 1.31. Correlation coefficients (r 2 ) between electrophysiological CSF and dynamic or static psychophysical CSF were, respectively, 0.81 and 0.45. CONCLUSIONS. Electrophysiological and psychophysical CSFs correlated more positively when temporal presentation was similar. Spatial frequencies higher than 2 cpd showed that at least two visual pathways sum their activities at high contrasts. At low contrast levels, the results suggest that the transient VEP is dominated by the magnocellular (M) pathway. (Invest Ophthalmol Vis Sci. 2007;48:3396 -3404) DOI:10.1167/iovs.07-0018 T he use of the visual evoked potential (VEP) to study the human spatial luminance contrast sensitivity started in the 1970s, when it was demonstrated that the steady state VEP amplitude decreases with stimulus log contrast after a straightline relationship. 1 Moreover, the steady state VEP was successfully used to derive the spatial luminance contrast sensitivity function (CSF) in humans. When compared with behavioral measurements, the electrophysiological CSF was similar to the psychophysical CSF. 1 It was also observed that at spatial frequencies between 1.5 and 3 cpd, the contrast response functions were describable by two regressions with different slopes. 1 Further studies in humans and nonhuman primates have reported such nonlinearity of the VEP amplitude as a function of the stimulus contrast 2-11 : either a straight-line relation for low contrasts followed by saturation at high contrasts or a double-slope straight-line relation such as those described earlier. Originally, it was proposed that these nonlinearities indicate the contribution of different retinal regions, 1 but more recent studies have suggested that the nonlinearities are related to different contrast sensitivity mechanisms from parallel visual pathways. 6,10 -12 In this study, we assessed the similarity of the spatial luminance CSF obtained with transient VEP, when compared with that obtained psychophysically with similar stimuli. We also analyzed whether transient VEP amplitudes can be related to visual parallel pathway sensitivities. The transient VEP can be used as an objective tool to study spatial luminance CSF. There was good agreement between the electrophysiological and psychophysical measurements obtained with the same temporal frequency. Our results suggest that the M pathway is the main source of the VEP amplitude, at least at low-luminance contrasts. Some of these results have been presented in abstract form (Souza et al. IOVS 2006;47:ARVO E-Abstract 5379). METHODS Subjects Six healthy adults (three men and three women; mean age, 21 Ϯ 2 years) were monocularly tested. For each subject, only the eye with smallest dioptric error was tested. All subjects had normal or corrected acuity to 20/20, which was assessed by measuring the eye's refractive state with an autorefractor/keratometer (Humphrey 599; Carl Zeiss Meditec, Dublin, CA). None of the participants reported previous ocular, neural, or systemic diseases that could affect the visual system. All procedures were performed according to the tenets of the Declaration of Helsinki and were approved by the Committe

Spatial luminance contrast sensitivity and color discrimination measured with transient visual evoked potential

Le potenciel évoqué visuel (VEP) est une réponse corticale qui peut être enregistrée à la surface du cuir chevelu. Il reflète l'activité des neurones de V1 et est classifié, selon la fréquence de stimulation temporale, en transitoire ou stationnaire. D'autres propriétés du stimulus semblent provoquer une activité sélective des divers groupes de neurones existants dans V1. Ainsi, le VEP est utilisé pour étudier la vision humaine achromatique et chromatique. Divers travaux ont utilisé le VEP pour estimer la sensibilité au contraste de luminance dans le domaine des fréquences spatiales. Plus récemment, des études ont utilisé le VEP pour mesurer les seuils de discrimination des couleurs. Le VEP transitoire peut compléter les mesures psychophysiques de sensibilité au contraste spatial de luminance et de discrimination chromatique et constitue une méthode non envahissante pour étudier la vision des sujets avec des difficultés à réaliser les tests psychophysiques.O potencial provocado visual (VEP) é uma resposta cortical registrável na superfície do couro cabeludo, que reflete a atividade dos neurônios de V1. é classificado, a partir da freqüência temporal de estimulação, em transiente ou de estado estacionário. Outras propriedades do estímulo parecem provocar uma atividade seletiva dos diversos grupos de neurônios existentes em V1. Desse modo, o VEP vem sendo usado para estudar a visão humana acromática e cromática. Diversos trabalhos usaram o VEP para estimar a sensibilidade ao contraste de luminância no domínio das freqüências espaciais. Mais recentemente, há estudos que empregaram o VEP para medir os limiares de discriminação de cores. O VEP transiente pode complementar as medidas psicofísicas de sensibilidade ao contraste espacial de luminância e de discriminação cromática, e constitui um método não invasivo para estudar a visão de indivíduos com dificuldades de realizar testes psicofísicos.The Visual Evoked Potential (VEP) is a cortical response obtainable on the scalp. It usually reflects the activity from V1 neurons. It is classified in transient or steady-state, according with the temporal frequency of stimulation. Other stimuli properties evoke a selective activity from different neuronal groups found in V1. This way, VEP have been used to study luminance and chromatic human vision. Several studies used VEP to estimate luminance contrast sensitivity in the spatial frequency domain. More recently, some studies used VEP to measure color discrimination thresholds. The transient VEP shows a good agreement with psychophysical measurements of spatial luminance contrast sensitivity and color discrimination, being a noninvasive method to study vision from subjects with difficulty to perform psychophysical tests

Estimativa da sensibilidade ao contraste espacial de luminância e discriminação de cores por meio do potencial provocado visual transiente

O potencial provocado visual (VEP) é uma resposta cortical registrável na superfície do couro cabeludo, que reflete a atividade dos neurônios de V1. é classificado, a partir da freqüência temporal de estimulação, em transiente ou de estado estacionário. Outras propriedades do estímulo parecem provocar uma atividade seletiva dos diversos grupos de neurônios existentes em V1. Desse modo, o VEP vem sendo usado para estudar a visão humana acromática e cromática. Diversos trabalhos usaram o VEP para estimar a sensibilidade ao contraste de luminância no domínio das freqüências espaciais. Mais recentemente, há estudos que empregaram o VEP para medir os limiares de discriminação de cores. O VEP transiente pode complementar as medidas psicofísicas de sensibilidade ao contraste espacial de luminância e de discriminação cromática, e constitui um método não invasivo para estudar a visão de indivíduos com dificuldades de realizar testes psicofísicos

Contrast sensitivity of pattern transient VEP components: contribution from M and P pathways

The purpose of this study was to compare contrast sensitivity estimated from transient visual evoked potentials (VEPs) elicited by achromatic pattern-reversal and pattern-onset/offset modes. The stimuli were 2-cpd, achromatic horizontal gratings presented either as a 1 Hz pattern reversal or a 300 ms onset/700 ms offset stimulus. Contrast thresholds were estimated by linear regression to amplitudes of VEP components vs. the logarithm of the stimulus contrasts, and these regressions were extrapolated to the zero amplitude level. Contrast sensitivity was defined as the inverse of contrast threshold. For pattern reversal, the relation between the P100 amplitude and log of the stimulus contrast was best described by two separate linear regressions. For the N135 component, a single straight line was sufficient. In the case of pattern onset/offset for both the C1 and C2 components, single straight lines described their amplitude vs. log contrast relations in the medium-to-low contrast range. Some saturation was observed for C2 components. The contrast sensitivity estimated from the low-contrast limb of the P100, from the N135, and from the C2 were all similar but higher than those obtained from the high-contrast limb of the P100 and C1 data, which were also similar to each other. With 2 cpd stimuli, a mechanism possibly driven by the M pathway appeared to contribute to the P100 component at medium-to-low contrasts and to the N135 and C2 components at all contrast levels, whereas another mechanism, possibly driven by the P and M pathways, appeared to contribute to the P100 component at high contrast and C1 component at all contrast levels

Division of labor between M and P visual pathways: different visual pathways minimize joint entropy differently

Visual perception and action are strongly linked with parallel processing channels connecting the retina, the lateral geniculate nucleus, and the input layers of the primary visual cortex. Achromatic vision is provided by at least two of such channels formed by the M and P neurons. These cell pathways are similarly organized in primates having different lifestyles, including species that are diurnal, nocturnal, and which exhibit a variety of color vision phenotypes. We describe the M and P cell properties by 3D Gábor functions and their 3D Fourier transform. The M and P cells occupy different loci in the Gábor information diagram or Fourier Space. This separation allows the M and P pathways to transmit visual signals with distinct 6D joint entropy for space, spatial frequency, time, and temporal frequency. By combining the M and P impacts on the cortical neurons beyond V1 input layers, the cortical pathways are able to process aspects of visual stimuli with a better precision than it would be possible using the M or P pathway alone. This performance fulfils the requirements of different behavioral tasks

<i>Alouatta</i> Trichromatic Color Vision: Cone Spectra and Physiological Responses Studied with Microspectrophotometry and Single Unit Retinal Electrophysiology

<div><p>The howler monkeys (<i>Alouatta</i> sp.) are the only New World primates to exhibit routine trichromacy. Both males and females have three cone photopigments. However, in contrast to Old World monkeys, <i>Alouatta</i> has a locus control region upstream of each opsin gene on the X-chromosome and this might influence the retinal organization underlying its color vision. Post-mortem microspectrophotometry (MSP) was performed on the retinae of two male <i>Alouatta</i> to obtain rod and cone spectral sensitivities. The MSP data were consistent with only a single opsin being expressed in each cone and electrophysiological data were consistent with this primate expressing full trichromacy. To study the physiological organization of the retina underlying <i>Alouatta</i> trichromacy, we recorded from retinal ganglion cells of the same animals used for MSP measurements with a variety of achromatic and chromatic stimulus protocols. We found MC cells and PC cells in the <i>Alouatta</i> retina with similar properties to those previously found in the retina of other trichromatic primates. MC cells showed strong phasic responses to luminance changes and little response to chromatic pulses. PC cells showed strong tonic response to chromatic changes and small tonic response to luminance changes. Responses to other stimulus protocols (flicker photometry; changing the relative phase of red and green modulated lights; temporal modulation transfer functions) were also similar to those recorded in other trichromatic primates. MC cells also showed a pronounced frequency double response to chromatic modulation, and with luminance modulation response saturation accompanied by a phase advance between 10–20 Hz, characteristic of a contrast gain mechanism. This indicates a very similar retinal organization to Old-World monkeys. Cone-specific opsin expression in the presence of a locus control region for each opsin may call into question the hypothesis that this region exclusively controls opsin expression.</p></div