Repeatability of the evaluation of systemic microvascular endothelial function using laser doppler perfusion monitoring: clinical and statistical implications

OBJECTIVE: An awareness of the repeatability of biological measures is required to properly design and calculate sample sizes for longitudinal interventional studies. We investigated the day-to-day repeatability of measures of systemic microvascular reactivity using laser Doppler perfusion monitoring. METHODS: We performed laser Doppler perfusion monitoring in combination with skin iontophoresis using acetylcholine and sodium nitroprusside as well as post-occlusive reactive and thermal hyperemia twice within two weeks. The repeatability was assessed by calculating the within-subject standard deviations, limits of agreement, typical errors and intra-class correlation coefficients between days 1 and 2. The ratio of the within-subject standard deviation to the mean values obtained on days 1 and 2 (within-subject standard deviation/GM) was used to determine the condition with the best repeatability. RESULTS: Twenty-four healthy subjects, aged 24.6 + 3.8 years, were recruited. The area under the curve of the vasodilatory response to post-occlusive reactivity showed marked variability (within-subject standard deviation/GM = 0.83), while the area under the curve for acetylcholine exhibited less variability (within-subject standard deviation/ GM = 0.52) and was comparable to the responses to sodium nitroprusside and thermal treatment (within-subject standard deviations/GM of 0.67 and 0.56, respectively). The area under the blood flow/time curve for vasodilation during acetylcholine administration required the smallest sample sizes, the area under the blood flow/time curve during post-occlusive reactivity required the largest sample sizes, and the area under the blood flow/time curves of vasodilation induced by sodium nitroprusside and thermal treatment required intermediate sizes. CONCLUSIONS: In view of the importance of random error related to the day-to-day repeatability of laser Doppler perfusion monitoring, we propose an original and robust statistical methodology for use in designing prospective clinical studies

A combined continuous-discontinuous finite element method for convection-diffusion problems

Discontinuous Galerkin (DGM) method combines the advantages of stability of finite volume method and the accuracy of continuous finite element method (FEIVI). Applications of the DGM are particularly valuable where the solution presents high-gradients or discontinuities, such as boundary layers and shock problems. A disadvantage of the DGM is the higher computational cost when comparing to classic finite element method, due to the increased number of degrees of freedom. With this motivation, in this paper we explore the idea of combining continuous and discontinuous Galerkin formulations for the simulation of convection-diffusion problems. The computational domain is decomposed into two parts. In one region the solution is supposed to be smooth, and the traditional continuous finite element method is applied. On the other hand, where steep gradients are expected, we use a, discontinuous Galerkin formulation. This paper presents numerical results for the combined FEM/DGM method applied to convection-diffusion problems.4322924

“A Good Death” - Palliative Surgery in Trisomy 18

A trissomia 18 caracteriza-se por múltiplas anomalias, incluindo doença cardíaca em 60 a 90% dos casos e elevada mortalidade. O mau prognóstico global, conduz habitualmente a uma politica de “cuidados mínimos” mas, paliar, é também nestas situações, um imperativo ético. Descreve-se o caso de uma recém-nascida sem diagnóstico pré natal, mas com confirmação por cariotipo, com cardiopatia, que condicionou insuficiência cardíaca congestiva e angústia respiratória crescente, inviabilizando alta hospitalar, como era desejo da família. Após consenso entre os pais e o corpo clínico responsável, foi decidida intervenção cirúrgica cardíaca paliativa, que possibilitou melhoria clínica e alta para o domicílio. Os autores defendem que a cirurgia cardíaca pode ser uma atitude a considerar em casos de trissomia 18, pois pode aliviar o sofrimento

Checking Whether an Automaton Is Monotonic Is NP-complete

An automaton is monotonic if its states can be arranged in a linear order that is preserved by the action of every letter. We prove that the problem of deciding whether a given automaton is monotonic is NP-complete. The same result is obtained for oriented automata, whose states can be arranged in a cyclic order. Moreover, both problems remain hard under the restriction to binary input alphabets.Comment: 13 pages, 4 figures. CIAA 2015. The final publication is available at http://link.springer.com/chapter/10.1007/978-3-319-22360-5_2

A genome-wide study of Hardy–Weinberg equilibrium with next generation sequence data

Statistical tests for Hardy–Weinberg equilibrium have been an important tool for detecting genotyping errors in the past, and remain important in the quality control of next generation sequence data. In this paper, we analyze complete chromosomes of the 1000 genomes project by using exact test procedures for autosomal and X-chromosomal variants. We find that the rate of disequilibrium largely exceeds what might be expected by chance alone for all chromosomes. Observed disequilibrium is, in about 60% of the cases, due to heterozygote excess. We suggest that most excess disequilibrium can be explained by sequencing problems, and hypothesize mechanisms that can explain exceptional heterozygosities. We report higher rates of disequilibrium for the MHC region on chromosome 6, regions flanking centromeres and p-arms of acrocentric chromosomes. We also detected long-range haplotypes and areas with incidental high disequilibrium. We report disequilibrium to be related to read depth, with variants having extreme read depths being more likely to be out of equilibrium. Disequilibrium rates were found to be 11 times higher in segmental duplications and simple tandem repeat regions. The variants with significant disequilibrium are seen to be concentrated in these areas. For next generation sequence data, Hardy–Weinberg disequilibrium seems to be a major indicator for copy number variation.Peer ReviewedPostprint (published version

What cost components are relevant for economic evaluations of palliative care, and what approaches are used to measure these costs? A systematic review

BACKGROUND: It is important to understand the costs of palliative and end-of-life care in order to inform decisions regarding cost allocation. However, economic research in palliative care is very limited and little is known about the range and extent of the costs that are involved in palliative care provision. AIM: To undertake a systematic review of the health and social care literature to determine the range of financial costs related to a palliative care approach and explore approaches used to measure these costs. DESIGN: A systematic review of empirical literature with thematic synthesis. Study quality was evaluated using the Weight of Evidence Framework. DATA SOURCES: The databases CINAHL, Cochrane, PsycINFO and Medline were searched from 1995 to November 2015 for empirical studies which presented data on the financial costs associated with palliative care. RESULTS: A total of 38 papers met our inclusion criteria. Components of palliative care costs were incurred within four broad domains: hospital care, community or home-based care, hospice care and informal care. These costs could be considered from the economic viewpoint of three providers: state or government, insurers/third-party/not-for-profit organisations and patient and family and/or society. A wide variety of costing approaches were used to derive costs. CONCLUSION: The evidence base regarding the economics of palliative care is sparse, particularly relating to the full economic costs of palliative care. Our review provides a framework for considering these costs from a variety of economic viewpoints; however, further research is required to develop and refine methodologies