Photorefractive keratectomy for low myopia correction using different ablation profiles

Objectives: The present study compares the results obtained with single zone PRK versus multiple zones PRK for treating low myopia. Methods: Nineteen patients presenting spherical equivalent up to 6.00 diopters of myopia, were submitted to PRK using two different approaches. Ramdomly one eye received a 6.0 mm spherical ablation (SZ) while the fellow eye was treated with two optical zones, 6.0 mm and 6.5 mm (MZ). All the procedures aimed to correct total spherical equivalent. Follow-up was carried out for at least 6 months. Results: The multizone group (MZ) presented a preoperative mean spherical equivalent of -2.87 diopters, ranging from -1.25 to -4.62D. In the single zone group, the mean spherical equivalent was -2.78 diopters, ranging from -1.37 to -4.62D. No significant difference was observed between the two groups considering final spherical equivalent (p=0.391). In the first postoperative month, 84% of the patients in the MZ group and 95% in the SZ group presented uncorrected visual acuity equal to or better than 20/40. No difference was detected regarding time necessary to achieve best uncorrected vision. Conclusion: Results obtained using different ablation profiles were similar in regard to spherical equivalent, induced astigmatism and complications. A better final uncorrected visual acuity trend was observed in the SZ group but it was not considered clinically significant. We believe that any of the evaluated approaches are valued methods for treating low myopia.Objetivos: O presente estudo prospectivo compara os resultados obtidos pela ceratectomia fotorrefrativa com uma ou duas zonas de ablação para tratamento de baixa miopia. Métodos: Dezenove pacientes com graus de miopia até 6,00 dioptrias foram submetidos a PRK com diferentes perfis de ablação em cada olho. Foi realizado tratamento esférico com uma única zona de ablação de 6,0 mm, ao passo que o outro olho recebeu tratamento com duas zonas de ablação, sendo uma de 6,0 mm e outra de 6,5 mm. Todos os tratamentos foram programados para correção total do equivalente esférico. Resultados: No grupo multizona (MZ), o equivalente esférico pré-operatório foi em média de -2,87 dioptrias (-1,25 a -4,62D). No grupo submetido à cirurgia com uma única zona de ablação (ZU), o equivalente esférico pré-operatório foi de -2,78 dioptrias (-1,37 a -4,62 D). Não foi observada diferença significante entre os resultados obtidos nos dois grupos com relação ao equivalente esférico final (p = 0,391). No primeiro mês de pós-operatório, 84% dos pacientes do grupo MZ (múltiplas zonas de ablação) e 95% do grupo ZU (única zona de ablação), apresentaram acuidade visual sem correção melhor ou igual a 20/40. Com relação ao tempo transcorrido até se atingir a melhor acuidade visual, não houve diferença significante entre os dois grupos (p = 0,53). Conclusão: Os resultados obtidos utilizando-se diferentes perfis de ablação para tratamento de baixas miopias foram equivalentes no que diz respeito a equivalente esférico final, indução de astigmatismo e incidência de complicações. O estudo conclui que não foi possível observar diferença estatisticamente significante entre os dois grupos, podendo-se utilizar qualquer um dos procedimentos no tratamento das baixas miopias.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de Medicina Departamento de OftalmologiaUNIFESP, EPM, Depto. de OftalmologiaSciEL

Color space distortions in patients with type 2 diabetes mellitus

Color vision impairment was examined in patients with type 2 diabetes mellitus (DM2) without retinopathy. We assessed the type and degree of distortions of individual color spaces. DM2 patients (n = 32), and age-matched controls (n = 20)were tested using the Farnsworth D-15 and the Lanthony D-15d tests. In addition, subsets of caps from both tests were employed in a triadic procedure (Bimler & Kirkland, 2004). Matrices of inter-cap subjective dissimilarities were estimated from each subject’s “odd-one-out” choices, and processed using non-metric multidimensional scaling. Two-dimensional color spaces, individual and group (DM2 patients; controls), were reconstructed, with the axes interpreted as the R0G and B0Y perceptual opponent systems. Compared to controls, patient results were not significant for the D-15 and D-15d. In contrast, in the triadic procedure the residual distances were significantly different compared to controls: right eye, P 0.021, and left eye, P 0.022. Color space configurations for the DM2 patients were compressed along the B0Y and R0G dimensions. The present findings agree with earlier studies demonstrating diffuse losses in early stages of DM2. The proposed method of testing uses color spaces to represent discrimination and provides more differentiated quantitative diagnosis, which may be interpreted as the perceptual color system affected. In addition, it enables the detection of very mild color vision impairment that is not captured by the D-15d test. Along with fundoscopy, individual color spaces may serve for monitoring early functional changes and thereby to support a treatment strategy

Non-abelian gauge structure in neutrino mixing

We discuss the existence of a non-abelian gauge structure associated with flavor mixing. In the specific case of two flavor mixing of Dirac neutrino fields, we show that this reformulation allows to define flavor neutrino states which preserve the Poincar\'e structure. Phenomenological consequences of our analysis are explored.Comment: 13 pages, 2 figure

Skeletal muscle stem cells express anti-apoptotic ErbB receptors during activation from quiescence

To be effective for tissue repair, satellite cells (the stem cells of adult muscle) must survive the initial activation from quiescence. Using an in vitro model of satellite cell activation, we show that erbB1, erbB2 and erbB3, members of the EGF receptor tyrosine kinase family, appear on satellite cells within 6 h of activation. We show that signalling via erbB2 provides an anti-apoptotic survival mechanism for satellite cells during the first 24 h, as they progress to a proliferative state. Inhibition of erbB2 signalling with AG825 reduced satellite cell numbers, concomitant with elevated caspase-8 activation and TUNEL labelling of apoptotic satellite cells. In serum-free conditions, satellite cell apoptosis could be largely prevented by a mixture of erbB1, erbB3 and erbB4 ligand growth factors, but not by neuregulin alone (erbB3/erbB4 ligand). Furthermore, using inhibitors specific to discrete intracellular signalling pathways, we identify MEK as a pro-apoptotic mediator, and the erbB-regulated factor STAT3 as an anti-apoptotic mediator during satellite cell activation. These results implicate erbB2 signalling in the preservation of a full compliment of satellite cells as they activate in the context of a damaged muscle

Contributions of mean and shape of blood pressure distribution to worldwide trends and variations in raised blood pressure: A pooled analysis of 1018 population-based measurement studies with 88.6 million participants

© The Author(s) 2018. Background: Change in the prevalence of raised blood pressure could be due to both shifts in the entire distribution of blood pressure (representing the combined effects of public health interventions and secular trends) and changes in its high-blood-pressure tail (representing successful clinical interventions to control blood pressure in the hypertensive population). Our aim was to quantify the contributions of these two phenomena to the worldwide trends in the prevalence of raised blood pressure. Methods: We pooled 1018 population-based studies with blood pressure measurements on 88.6 million participants from 1985 to 2016. We first calculated mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP) and prevalence of raised blood pressure by sex and 10-year age group from 20-29 years to 70-79 years in each study, taking into account complex survey design and survey sample weights, where relevant. We used a linear mixed effect model to quantify the association between (probittransformed) prevalence of raised blood pressure and age-group- and sex-specific mean blood pressure. We calculated the contributions of change in mean SBP and DBP, and of change in the prevalence-mean association, to the change in prevalence of raised blood pressure. Results: In 2005-16, at the same level of population mean SBP and DBP, men and women in South Asia and in Central Asia, the Middle East and North Africa would have the highest prevalence of raised blood pressure, and men and women in the highincome Asia Pacific and high-income Western regions would have the lowest. In most region-sex-age groups where the prevalence of raised blood pressure declined, one half or more of the decline was due to the decline in mean blood pressure. Where prevalence of raised blood pressure has increased, the change was entirely driven by increasing mean blood pressure, offset partly by the change in the prevalence-mean association. Conclusions: Change in mean blood pressure is the main driver of the worldwide change in the prevalence of raised blood pressure, but change in the high-blood-pressure tail of the distribution has also contributed to the change in prevalence, especially in older age groups

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities(.)(1,2) This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity(3-6). Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55% of the global rise in mean BMI from 1985 to 2017-and more than 80% in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.Peer reviewe

Non-invasive diagnostic tests for Helicobacter pylori infection

BACKGROUND: Helicobacter pylori (H pylori) infection has been implicated in a number of malignancies and non-malignant conditions including peptic ulcers, non-ulcer dyspepsia, recurrent peptic ulcer bleeding, unexplained iron deficiency anaemia, idiopathic thrombocytopaenia purpura, and colorectal adenomas. The confirmatory diagnosis of H pylori is by endoscopic biopsy, followed by histopathological examination using haemotoxylin and eosin (H & E) stain or special stains such as Giemsa stain and Warthin-Starry stain. Special stains are more accurate than H & E stain. There is significant uncertainty about the diagnostic accuracy of non-invasive tests for diagnosis of H pylori. OBJECTIVES: To compare the diagnostic accuracy of urea breath test, serology, and stool antigen test, used alone or in combination, for diagnosis of H pylori infection in symptomatic and asymptomatic people, so that eradication therapy for H pylori can be started. SEARCH METHODS: We searched MEDLINE, Embase, the Science Citation Index and the National Institute for Health Research Health Technology Assessment Database on 4 March 2016. We screened references in the included studies to identify additional studies. We also conducted citation searches of relevant studies, most recently on 4 December 2016. We did not restrict studies by language or publication status, or whether data were collected prospectively or retrospectively. SELECTION CRITERIA: We included diagnostic accuracy studies that evaluated at least one of the index tests (urea breath test using isotopes such as13C or14C, serology and stool antigen test) against the reference standard (histopathological examination using H & E stain, special stains or immunohistochemical stain) in people suspected of having H pylori infection. DATA COLLECTION AND ANALYSIS: Two review authors independently screened the references to identify relevant studies and independently extracted data. We assessed the methodological quality of studies using the QUADAS-2 tool. We performed meta-analysis by using the hierarchical summary receiver operating characteristic (HSROC) model to estimate and compare SROC curves. Where appropriate, we used bivariate or univariate logistic regression models to estimate summary sensitivities and specificities. MAIN RESULTS: We included 101 studies involving 11,003 participants, of which 5839 participants (53.1%) had H pylori infection. The prevalence of H pylori infection in the studies ranged from 15.2% to 94.7%, with a median prevalence of 53.7% (interquartile range 42.0% to 66.5%). Most of the studies (57%) included participants with dyspepsia and 53 studies excluded participants who recently had proton pump inhibitors or antibiotics.There was at least an unclear risk of bias or unclear applicability concern for each study.Of the 101 studies, 15 compared the accuracy of two index tests and two studies compared the accuracy of three index tests. Thirty-four studies (4242 participants) evaluated serology; 29 studies (2988 participants) evaluated stool antigen test; 34 studies (3139 participants) evaluated urea breath test-13C; 21 studies (1810 participants) evaluated urea breath test-14C; and two studies (127 participants) evaluated urea breath test but did not report the isotope used. The thresholds used to define test positivity and the staining techniques used for histopathological examination (reference standard) varied between studies. Due to sparse data for each threshold reported, it was not possible to identify the best threshold for each test.Using data from 99 studies in an indirect test comparison, there was statistical evidence of a difference in diagnostic accuracy between urea breath test-13C, urea breath test-14C, serology and stool antigen test (P = 0.024). The diagnostic odds ratios for urea breath test-13C, urea breath test-14C, serology, and stool antigen test were 153 (95% confidence interval (CI) 73.7 to 316), 105 (95% CI 74.0 to 150), 47.4 (95% CI 25.5 to 88.1) and 45.1 (95% CI 24.2 to 84.1). The sensitivity (95% CI) estimated at a fixed specificity of 0.90 (median from studies across the four tests), was 0.94 (95% CI 0.89 to 0.97) for urea breath test-13C, 0.92 (95% CI 0.89 to 0.94) for urea breath test-14C, 0.84 (95% CI 0.74 to 0.91) for serology, and 0.83 (95% CI 0.73 to 0.90) for stool antigen test. This implies that on average, given a specificity of 0.90 and prevalence of 53.7% (median specificity and prevalence in the studies), out of 1000 people tested for H pylori infection, there will be 46 false positives (people without H pylori infection who will be diagnosed as having H pylori infection). In this hypothetical cohort, urea breath test-13C, urea breath test-14C, serology, and stool antigen test will give 30 (95% CI 15 to 58), 42 (95% CI 30 to 58), 86 (95% CI 50 to 140), and 89 (95% CI 52 to 146) false negatives respectively (people with H pylori infection for whom the diagnosis of H pylori will be missed).Direct comparisons were based on few head-to-head studies. The ratios of diagnostic odds ratios (DORs) were 0.68 (95% CI 0.12 to 3.70; P = 0.56) for urea breath test-13C versus serology (seven studies), and 0.88 (95% CI 0.14 to 5.56; P = 0.84) for urea breath test-13C versus stool antigen test (seven studies). The 95% CIs of these estimates overlap with those of the ratios of DORs from the indirect comparison. Data were limited or unavailable for meta-analysis of other direct comparisons. AUTHORS' CONCLUSIONS: In people without a history of gastrectomy and those who have not recently had antibiotics or proton ,pump inhibitors, urea breath tests had high diagnostic accuracy while serology and stool antigen tests were less accurate for diagnosis of Helicobacter pylori infection.This is based on an indirect test comparison (with potential for bias due to confounding), as evidence from direct comparisons was limited or unavailable. The thresholds used for these tests were highly variable and we were unable to identify specific thresholds that might be useful in clinical practice.We need further comparative studies of high methodological quality to obtain more reliable evidence of relative accuracy between the tests. Such studies should be conducted prospectively in a representative spectrum of participants and clearly reported to ensure low risk of bias. Most importantly, studies should prespecify and clearly report thresholds used, and should avoid inappropriate exclusions

Frequência da microftalmia associada à catarata congênita, sua frequência etiológica e o resultado visual pós-cirúrgico

Resumo Objetivo: Determinar a frequência da microftalmia associada à catarata congênita e sua frequência etiológica. Comparar o resultado visual após a cirurgia da catarata congênita em olhos microftálmicos, com o resultado visual obtido em olhos não microftálmicos. Método: Estudo retrospectivo de 76 pacientes portadores de microftalmia e catarata congênita, selecionados após análise de 1050 prontuários dos pacientes atendidos no ambulatório de catarata congênita da UNIFESP. A microftalmia foi determinada pela ecobiometria ultrassonica. Exames oculares e complementares foram feitos para esclarecer a causa etiológica. O resultado visual pós- operatório do Grupo I (com microftalmia) foi confrontado com o resultado visual obtido no Grupo II (sem microftalmia). Resultados: O diâmetro ântero-posterior dos olhos microftálmicos variou de 13 à 21 mm. A frequência etiológica da catarata congênita associada aos olhos microftálmicos foi assim distribuída: doenças infecciosas (55,3%); seguidos de idiopáticas (26,3%), colobomas (7,9%), hereditárias (6,6%), persistência do vítreo primário hiperplásico (2,6%) e associada à síndrome de Lenz (1,3%) .A frequência da microftalmia foi de 7,23 %. 68,3% de olhos afácicos microftálmicos atingiram visão melhor e ou igual à 20/200. Conclusão: A frequência da microftalmia associada à catarata congênita foi de 7,23%. A maior frequência etiológica ocorreu nas doenças infecciosas (55,3%), Embora os olhos microftálmicos tenham tendência para piores resultados visuais quando comparados aos não microftálmicos, nesta pesquisa os olhos microftálmicos afácicos que atingiram visão melhor ou igual a 20/200 foram de 68,3%