Asymptotic Expansions for Stationary Distributions of Perturbed Semi-Markov Processes

New algorithms for computing of asymptotic expansions for stationary distributions of nonlinearly perturbed semi-Markov processes are presented. The algorithms are based on special techniques of sequential phase space reduction, which can be applied to processes with asymptotically coupled and uncoupled finite phase spaces.Comment: 83 page

Self-reported sleep duration and cognitive performance in older adults: a systematic review and meta-analysis

AbstractSleep is important for optimal cognitive functioning across the lifespan. Among older adults (≥55 years), self-reported short and long sleep durations have been repeatedly, albeit inconsistently, reported to elevate the risk for poor cognitive function. This meta-analytic review quantitatively summarizes the risk for poorer cognitive function among short and long sleepers in older adults. Eligible publications were searched online and manually. A total of 35 independent samples (N = 97,264) from 11 cross-sectional and seven prospective cohort studies were included. Pooled odds ratios (OR) with 95% confidence intervals (CI) were derived using random-effects models. Self-reported short and long sleep increased the odds for poor cognitive function by 1.40 (CI = 1.27–1.56) and 1.58 times (CI = 1.43–1.74), respectively. Effect sizes varied across studies and may have been moderated by both study type (cross-sectional and prospective) and cognitive domain assessed. For cross-sectional studies, extreme sleep durations were significantly associated with poorer multiple-domain performance, executive functions, verbal memory, and working memory capacity. Prospective cohort studies revealed the significant long-term impact of short and long sleep on multiple-domain performance only. These findings establish self-reported extreme sleep duration as a risk factor for cognitive aging

Morphological analysis of the corneal endothelium in eyes of dogs using specular microscopy Análise morfológica com microscopia especular do endotélio corneal em olhos de cães

Both healthy eyes of 10 six-year-old male and female mongrel dogs were studied. With a contact specular microscope the corneal endothelium was examined. Endothelial cells were analyzed in the central and peripheral cornea. Morphological analysis with regard to polymegathism and pleomorphism was performed. Three images of each region with at least 100 cells were obtained. The analysis showed that polygonal cells formed a mosaic-like pattern uniform in size and shape. The predominant number of cells was hexagonal. The polymegathism index was 0.22. The study demonstrates that the morphology of the normal corneal endothelial cells of dogs is similar to that found in the human cornea.<br>Foram estudados 20 olhos de 10 cães sem raça definida, machos e fêmeas com 6 anos de idade. A morfologia das células do endotélio da córnea foi analisada utilizando-se microscópio especular de contato. Foram estudadas as regiões central e periférica da córnea. De cada região da córnea foram realizadas três micrografias. De cada micrografia foram analisadas no mínimo 100 células endoteliais. Foram obtidos os valores do polimegatismo e pleomorfismo. O endotélio corneano de cães caracterizou-se por uma monocamada de células poligonais uniformes em tamanho e forma. A forma predominante das células endoteliais foi hexagonal. O índice de polimegatismo foi 0.22. Este estudo demonstrou que a morfologia das células do endotélio da córnea de cães é semelhante à observada em humanos

Ultrastructural morphology and morphometry of the normal corneal endothelium of adult crossbred pig Morfologia ultraestrutural e morfometria do endotélio corneal normal de suínos adultos mestiços

Corneal endothelium constitutes a monolayer of polygonal cells. The integrity and health of this layer are essential for the maintenance of normal corneal transparency. This study reported by the first time in a detailed way the ultrastructural morphology and morphometry of the corneal endothelium in normal adult crossbred pigs by using scanning electron microscopy (SEM). A regular pattern of polygonal cells, with predominantly hexagonal cells and clear cell borders, was observed. An oval nucleus that bulges in the centre of the cell, cilia (2-4) in a few peripheral cells, openings of the pinocytotic vesicles, microvilli, borders bars and interdigitated cell borders were observed. The mean endothelial cell area was significantly higher (P<0.05) in the centre than in periphery, with a lower variation coefficient in the former. The mean cell density in periphery was significantly higher (P<0.05) than in centre and 43.9% higher than data formerly reported by other authors using specular microscopy, showing the significant shrinkage caused by sample processing for SEM. The mean value of cell sides (pleomorfism) was 5.9, ie. predominant hexagonal shape. The percentage of hexagonal cells was significantly higher in central region (P<0.01), determining a more homogeneous structure. The parameters obtained in this study will be a basement for future investigations about the effect on pig corneal endothelium of drugs, intracamerular surgeries and storage solutions for transplants.<br>O endotélio corneal é uma monocamada de células poligonais. A integridade e saúde dessa camada são essenciais para a manutenção da transparência corneal normal. Este estudo reportou pela primeira vez, de forma detalhada, a morfologia ultra-estrutural e a morfometria do endotélio corneal de suínos adultos mestiços à microscopia eletrônica de varredura (MEV). A superfície endothelial corneal apresentou um padrão regular de células poligonais, com predomínio da forma hexagonal e de bordas celulares nítidas. O núcleo foi observado como protuberância arredondada no centro da célula. Também foram observados os cílios (2-4) em apenas algumas células da região periférica da córnea, as aberturas das vesículas pinocitóticas na proximidade dos cílios, as microvilosidades, as varas da borda e as bordas celulares em formato de zigzag. A área celular média foi significativamente maior (P<0,05) no centro da córnea do que na periferia, com um coeficiente de variação menor no centro da córnea. A densidade celular média foi significativamente maior na periferia (P<0,05) e 43,9% maior que os dados reportados por outros autores na microscopia especular, o que demonstra o efeito da retração celular durante o processamento das amostras. O valor médio do número de lados das células (pleomorfismo) foi de 5,9, o que evidencia um predomínio do formato hexagonal. A percentagem de células hexagonais foi significativamente maior no centro (P<0,001). Os parâmetros obtidos nesta pesquisa servirão de base para estudos futuros sobre o efeito de medicamentos, cirurgias intracamerulares ou soluções para armazenamento de córneas para transplantes no endotélio corneal do suíno

Upstream stimulating factors: highly versatile stress-responsive transcription factors

International audienceUpstream stimulating factors (USF), USF-1 and USF-2, are members of the eucaryotic evolutionary conserved basic-Helix-Loop-Helix-Leucine Zipper transcription factor family. They interact with high affinity to cognate E-box regulatory elements (CANNTG), which are largely represented across the whole genome in eucaryotes. The ubiquitously expressed USF-transcription factors participate in distinct transcriptional processes, mediating recruitment of chromatin remodelling enzymes and interacting with co-activators and members of the transcription pre-initiation complex. Results obtained from both cell lines and knock-out mice indicates that USF factors are key regulators of a wide number of gene regulation networks, including the stress and immune responses, cell cycle and proliferation, lipid and glucid metabolism, and in melanocytes USF-1 has been implicated as a key UV-activated regulator of genes associated with pigmentation. This review will focus on general characteristics of the USF-transcription factors and their place in some regulatory networks