Pontos de corte para diagnóstico de sarcopenia em idosos a partir da força muscular de membros superiores e inferiores com ajustes alométricos

A presente tese defende a normalização da força e da massa muscular pelo tamanho corporal como estratégia eficiente para minimizar o viés das dimensões corporais sobre a funcionalidade de idosos. A tese foi composta de três objetivos específicos respondidos em quatro estudos originais. O primeiro objetivo foi propor expoentes alométricos para normalizar a força de membros superiores e inferiores pelo tamanho corporal e gerar pontos de corte para a fraqueza muscular de idosos, respondido em dois estudos originais. No Estudo I (Identification of muscle weakness in older adults from normalized upper and lower limbs strength: A cross-sectional study), que envolveu 94 idosos (IC 95%: 68,2 a 73,9 anos) de ambos os sexos, foram obtidas medidas de força muscular (preensão manual, extensão de joelhos dinâmica e isocinética), do tamanho corporal (antropometria, dimensões e índices) e mobilidade. Foram aplicadas estratégias de normalização (força/tamanho corporal) e alometria (força/tamanho corporalb; sendo b o expoente alométrico) associado à mobilidade dos idosos. Foram gerados 49 modelos válidos para identificar fraqueza muscular. A normalização aumentou a precisão dos pontos de corte em mulheres, mas não em homens. Todavia os ajustes nos homens também tornaram a força muscular independente do tamanho corporal, reduzindo o enviesamento para casos extremos. Isso implicou em menor risco de atribuir um diagnóstico falso-positiva/negativo à fraqueza muscular. E no Estudo II (Allometrically adjusted grip strength to identify low strength from 13,235 older adults of low- and middle-income countries), que envolveu idosos de ambos os sexos oriundos de seis países em desenvolvimento, a normalização da força muscular por dimensões corporais foi replicada em diferentes populações. Os métodos foram similares ao Estudo I, mas envolveu somente medidas da força de preensão manual, estatura e massa corporal. A relação não linear entre força e massa corporal foi confirmada, exceto para estatura. Os ajustes alométricos tornaram a força muscular independente do tamanho corporal e sua variabilidade destacou a necessidade de pontos de corte específicos para cada país. Os valores dos expoentes alométricos gerados para cada país foram muito próximos, confirmando a efetividade universal dessa estratégia. Nosso segundo objetivo foi aplicar comparativamente os expoentes alométricos propostos no Estudo I e outros relatados na literatura, a testar sua eficácia em normalizar a força e identificar fraqueza muscular. Assim, no Estudo III (Foreign allometric exponents adequately normalize isokinetic knee extension strength to identify muscle weakness and functional limitation in Portuguese older adults: A cross-sectional study) 132 idosos portugueses de ambos os sexos realizaram testes de mobilidade, força isocinética de extensão do joelho e medidas das dimensões corporais para normalizar a força (força/tamanho corporalb). Foram definidos pontos de corte para fraqueza muscular (curva ROC) a partir da força de extensão isocinética do joelho normalizada, ou não, identificado pelo menor quartil de mobilidade. Os pontos de corte da força absoluta, mostraram acurácia insuficiente (AUC<0.70). Expoentes alométricos, ainda que estrangeiros (três brasileiros e um norte americano), melhoraram a acurácia diagnóstica de fraqueza muscular. Concluímos que normalizar a força muscular isocinética de extensão do joelho, mesmo com o uso de expoentes alométricos estrangeiros é melhor do que nenhum ajuste. Nosso terceiro objetivo foi buscar uma estratégia simplificada para identificar a baixa massa muscular de idosos, baseada na limitação funcional para o risco de sarcopenia. Assim, para o Estudo IV (Normalizing Calf Circumference to identify low Skeletal Muscle Mass in Older Women: A Cross-sectional Study) foram propostos pontos de corte para o perímetro da panturrilha, normalizado pelo tamanho corporal, para identificar baixa massa muscular esquelética em mulheres idosas. Valores do perímetro da panturrilha de mulheres jovens (n=78) foram utilizados como referencia dos pontos de corte de baixa massa muscular (-2 desvio padrão). Os resultados mostraram que o perímetro da panturrilha normalizado pelo IMC identificou baixa massa muscular com maior acurácia do que os valores absolutos. A normalização retirou o costumeiro viés da relação de U invertido com a mobilidade (6MWT), geralmente observado em valores absolutos. A precisão obtida suportou o uso de PP·IMC-1 para identificar baixa massa muscular em mulheres idosas. Por conclusão, A estratégia alométrica proposta evita erros na classificação da baixa força muscular de idosos, decorrentes do viés causado pelo tamanho corporal. Possivelmente, isso reduz consideravelmente as chances de diagnósticos de casos falso positivos e negativos de sarcopenia em dimensões corporais de idosos com valores extremos. Palavras-chave: ajuste, alometricamente normalizado, avaliação, incapacidade, fragilidade, funcionalidade/estado funcional, medida, sarcopeniaThis thesis defends the normalization of strength and muscle mass by body size as an efficient strategy to minimize the bias of body dimensions on the functionality of the older adults. The thesis consisted of three specific objectives answered in four original studies. The first objective was to propose allometric exponents to normalize the strength of upper and lower limbs by body size and generate cutoff points for muscle weakness in the older adults, which was answered in two original studies. In Study I (Identification of muscle weakness in older adults from normalized upper and lower limbs strength: A cross-sectional study), which involved 94 older people (95% CI: 68.2 to 73.9 years) of both sexes, were muscle strength measurements were obtained (hand grip, dynamic and isokinetic knee extension), body size (anthropometry, dimensions, and indexes) and mobility. Strategies for normalization (strength/body size) and allometry (strength/body sizeb; b being the allometric exponent) associated with the mobility of the older adults were applied. Were generated 49 valid models to identify muscle weakness. Normalization increased the precision of the cut-off points in women but not in men. However, adjustments in men also made muscle strength independent of body size, reducing the bias for extreme cases. This implied a lower risk of attributing a falsepositive/ negative diagnosis to muscle weakness. And in Study II (Allometrically adjusted grip strength to identify low strength from 13,235 older adults of low- and middle-income countries), which involved older adults of both sexes from six developing countries, the normalization of muscle strength by body dimensions was replicated in different populations. The methods were like Study I, but only involved measurements of handgrip strength, height, and body mass. The non-linear relationship between strength and body mass was confirmed, except for height. Allometric adjustments made muscle strength independent of body size, and their variability highlighted the need for country-specific cutoff points. The values of allometric exponents generated for each country were very close to, confirming the universal effectiveness of this strategy. Our second objective was to comparatively apply the allometric exponents proposed in Study I and others reported in the literature, to test their effectiveness in normalizing strength and identifying muscle weakness. Thus, in Study III (Foreign allometric exponents suitably normalize isokinetic knee extension strength to identify muscle weakness and functional limitation in Portuguese older adults: A cross-sectional study) 132 Portuguese older adults of both genders performed tests of mobility, isokinetic strength of breast extension. knee and body dimension measurements to normalize strength (strength/body sizeb). Cutoff points for muscle weakness (ROC curve) were defined based on the normalized isokinetic knee extension strength, or not, identified by the lowest mobility quartile. The absolute strength cut-off points showed insufficient accuracy (AUC<0.70). Allometric exponents, although foreign (three Brazilians and one North American), improved the diagnostic accuracy of muscle weakness. We conclude that normalizing isokinetic knee extension muscle strength, even with the use of foreign allometric exponents, is better than no adjustment. Our third objective was to seek a simplified strategy to identify low muscle mass during aging, based on functional limitation for the risk of sarcopenia. Thus, for Study IV (Normalizing Calf Circumference to identify low Skeletal Muscle Mass in Older Women: A Cross-sectional Study) cut-off points were proposed for the calf perimeter, normalized by body size, to identify low skeletal muscle mass in older women. Calf circumference values for young women (n=78) were used as a reference for low muscle mass cutoff points (-2 standard deviation). The results showed that the calf perimeter normalized by BMI identified low muscle mass with greater accuracy than the absolute values. Normalization removed the usual bias of the inverted U-to-mobility ratio (6MWT), usually seen in absolute values. The accuracy obtained supported the use of PP·BMI-1 to identify low muscle mass in older women. In conclusion, the proposed allometric strategy avoids errors in the classification of low muscle strength in the older adults, resulting from the bias caused by body size. Possibly, this considerably reduces the chances of diagnosing false positive and negative cases of sarcopenia in body dimensions of older people with extreme values

Community Detection with a Subsampled Semidefinite Program

Semidefinite programming is an important tool to tackle several problems in data science and signal processing, including clustering and community detection. However, semidefinite programs are often slow in practice, so speed up techniques such as sketching are often considered. In the context of community detection in the stochastic block model, Mixon and Xie [9] have recently proposed a sketching framework in which a semidefinite program is solved only on a subsampled subgraph of the network, giving rise to significant computational savings. In this short paper, we provide a positive answer to a conjecture of Mixon and Xie about the statistical limits of this technique for the stochastic block model with two balanced communities.Comment: 7 pages, 0 figure

Guarantees for Spontaneous Synchronization on Random Geometric Graphs

The Kuramoto model is a classical mathematical model in the field of non-linear dynamical systems that describes the evolution of coupled oscillators in a network that may reach a synchronous state. The relationship between the network's topology and whether the oscillators synchronize is a central question in the field of synchronization, and random graphs are often employed as a proxy for complex networks. On the other hand, the random graphs on which the Kuramoto model is rigorously analyzed in the literature are homogeneous models and fail to capture the underlying geometric structure that appears in several examples. In this work, we leverage tools from random matrix theory, random graphs, and mathematical statistics to prove that the Kuramoto model on a random geometric graph on the sphere synchronizes with probability tending to one as the number of nodes tends to infinity. To the best of our knowledge, this is the first rigorous result for the Kuramoto model on random geometric graphs

Selenium Fertilization in Tropical Pastures

Brazil is one of the largest meat producers. Meat along with other animal products have been responsible for its larger contribution as source of selenium (Se) for human. However, Se deficiency remains a concern because researches have indicated that this nutrient is found in low levels in Brazilian diet. Cattle in Brazil are fed basically from pasture, but there are strong evidences that soils contain low availability of Se; consequently plants and animals incorporate low Se levels. Pastures, Se fertilized, bring benefits to nutrition and health of animal consequently to humans already known in some countries. In contrast, Se fertilization on tropical weathered soils and tropical forages is little known. However, Se management as fertilizer in tropical environments requires researches involving field experiments, especially with animals, for establishing of safe and effective Se recommendations as fertilizer due to the Se toxicity potential and complexity in system of soil-plant-animal-human

Foreground Subtraction in Intensity Mapping with the SKA

21cm intensity mapping experiments aim to observe the diffuse neutral hydrogen (HI) distribution on large scales which traces the Cosmic structure. The Square Kilometre Array (SKA) will have the capacity to measure the 21cm signal over a large fraction of the sky. However, the redshifted 21cm signal in the respective frequencies is faint compared to the Galactic foregrounds produced by synchrotron and free-free electron emission. In this article, we review selected foreground subtraction methods suggested to effectively separate the 21cm signal from the foregrounds with intensity mapping simulations or data. We simulate an intensity mapping experiment feasible with SKA phase 1 including extragalactic and Galactic foregrounds. We give an example of the residuals of the foreground subtraction with a independent component analysis and show that the angular power spectrum is recovered within the statistical errors on most scales. Additionally, the scale of the Baryon Acoustic Oscillations is shown to be unaffected by foreground subtraction.Comment: This article is part of the 'SKA Cosmology Chapter, Advancing Astrophysics with the SKA (AASKA14), Conference, Giardini Naxos (Italy), June 9th-13th 2014

Effects of Low Salinity Water Ion Composition on Wettability Alteration in Sandstone Reservoir Rock: A Laboratory Investigation

For various decades, water-flooding mechanisms have been playing important role for improving oil recovery. It was not until recently that researchers discovered that the ionic strength of the brine was substantial. With regard to this, many studies started being published which focused more on the comparison of effects of having high ionic strength and low ionic strength for brine during flooding processes. Low salinity water comprises brine concentration below 5000ppm. At optimum concentration, low salinity water (LSW) when injected into the reservoir enhances the oil recovery considerably. This is attributed to the change of reservoir rock wettability. The process governing these changes are not well understood thus requiring a scrupulous investigation. Moreover there is no a certain fixed salinity range. This study investigates wettability alteration of Berea sandstone rock with brine of different ion composition (NaCl, KCl, MgCl2, CaCl2, and formation water-mostly Mg2+ and Ca2+ ions) and strength (500ppm-6500ppm with exception of formation water which consisted of 13000ppm). For the study, (31) core slabs were extracted from the core plug then saturated with formation water (FW). Next, the slabs underwent aging process in crude oil at ambient pressure and a temperature of 800c. Later, the slabs were removed and immersed in containers with low salinity water at different ionic composition and strength, which is mentioned. The wettability was measured by applying the sessile drop method in certain range of time. According to the results, there have been significantly great change of wettability at Low salinity water in case of KCl was observed. Keywords: ionic strength, wettability, low salinity water, saturation, brine compositio

Validity of the two-minute step test for healthy older adults.

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Rubinstein – Taybi in Syndrome a Peruvian patient with mild mental retardation: A case report / Síndrome de Rubinstein - Taybi em um paciente Peruano com leve retardo mental: Um relato de caso

Rubisntein-Taybi syndrome is of genetic origin, caused by a mutation in the CREBBP gene, which undergoes classic phenotypic changes and changes in neuropsychomotor development. In this sense, this article aims to report the case of a Peruvian patient with the clinical and genotypic diagnosis of the disease. During the prenatal period, the fetus did not have alterations that would suggest the syndrome, but at birth, it had a hemangioma, but without clinical repercussion. In the first three months of life, its development was normal, but from the fourth month on, delays were noticed. At 6 months of age, he was not holding his head, so the parents looked for a geneticist who first made the clinical diagnosis and then requested the karyotype, which confirmed the diagnosis. With this, he already started with multidisciplinary treatment and was still placed to study in regular schools in order to improve his development. Currently, at the age of 15, the patient is in treatment with a multidisciplinary approach and in a school to include children with some neurological weakness in the social environment, in order to avoid bullying from other colleagues. He presents phenotypic alterations characteristic of the syndrome, but the cognitive delay is mild when compared to other adolescents with the same pathology. Therefore, this work shows the need for diagnosis and a multidisciplinary approach in treatment. Even so, more studies are needed to learn more about this syndrome and thus provide a better safeguard of the lives of the patients, as occurred in the case of this patient

Ocorrência de Secreção Apócrina nas Células Epiteliais do Intestino de Larvas de Aedes aegypti L., Anopheles albitarsis Lynch-Arribálzaga e Culex quinquefasciatus Say (Diptera: Culicidae): Um Mecanismo de Defesa contra Infecção Causada por Bacillus sphaericus Neide?

Cell hypertrophy was the first reaction of the gut epithelial cells of Aedes aegypti (L.), Anopheles albitarsis (Lynch-Arribálzaga) and Culex quinquefasciatus (Say) to the toxins of strains 2362 and S1116 of Bacillus sphaericus, as cells had an increase of intracellular secretory activity. Soon after the cell hypertrophy developed, vesicles were formed at the cell apical portion, which detached with the plasma membrane, characterizing a type of apocrine secretion like. The first pathway of contamination of the mosquito larvae by these bacteria is through the gut, by feeding. Depending on the species of Culicidae and on the bacterial strain used, the hypertrophy of the gut epithelium occurred between 5 and 15 min after exposure to the contaminated environment. The second aspect observed after hypertrophy was the increase in apocrine secretion. The basophilic vesicles that detached from the cells remained between the peritrophic membrane and the gut lumen, such vesicles were filled with material of unknown nature. The gut posterior region showed secretory activity in both control and treated larvae, being much more intense in bacteria-exposed larvae. There were remarkable differences in the epithelial cell reaction according to the toxins of the two bacterial strains, but C. quinquefasciatus was the most susceptible. Differences in the gut cell reactions to the toxins produced by the two bacterial strains are discussed