Sleep disturbance in clinical and preclinical scrapie-infected sheep measured by polysomnography.

Neurodegenerative diseases are characterised by neuronal loss and abnormal deposition of pathological proteins in the nervous system. Among the most common neurodegenerative diseases are Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease and transmissible spongiform encephalopathies (TSEs). Sleep and circadian rhythm disturbances are one of the most common symptoms in patients with neurodegenerative diseases. Currently, one of the main objectives in the study of TSEs is to try to establish an early diagnosis, as clinical signs do not appear until the damage to the central nervous system is very advanced, which prevents any therapeutic approach. In this paper, we provide the first description of sleep disturbance caused by classical scrapie in clinical and preclinical sheep using polysomnography compared to healthy controls. Fifteen sheep classified into three groups, clinical, preclinical and negative control, were analysed. The results show a decrease in total sleep time as the disease progresses, with significant changes between control, clinical and pre-clinical animals. The results also show an increase in sleep fragmentation in clinical animals compared to preclinical and control animals. In addition, sheep with clinical scrapie show a total loss of Rapid Eye Movement sleep (REM) and alterations in Non Rapid Eyes Movement sleep (NREM) compared to control sheep, demonstrating more shallow sleep. Although further research is needed, these results suggest that prion diseases also produce sleep disturbances in animals and that polysomnography could be a diagnostic tool of interest in clinical and preclinical cases of prion diseases.

Hepatic hematopoiesis in the alpaca (Vicugna pacos), a species with development in hypoxic environments.

Hematopoiesis occurs in different anatomical niches throughout the life of the individual. The first hematopoietic extra-embryonic stage is replaced by a intra-embryonic stage that occurs in a region that is adjacent to the dorsal aorta. Then, the prenatal hematopoietic function is continued by the liver and spleen, and later by the bone marrow. The objective of the present work was to describe the morphological characteristics of hepatic hematopoiesis in the alpaca and to analyze the proportion of the hematopoietic compartment of the organ and the cell types, at different times of ontogeny. Sixty-two alpaca samples were collected from the municipal slaughterhouse of Huancavelica, Perú. They were processed by routine histological techniques. Hematoxylin-eosin staining, special dyes, immunohistochemical techniques and supplementary analyses by lectinhistochemistry, were performed. The prenatal liver is an important structure in the expansion and differentiation of hematopoietic stem cells. Their hematopoietic activity was characterized by four stages: initiation, expansion, peak, and involution. The liver started its hematopoietic function at 21 days EGA and it was maintained until shortly before birth. Differences were found in the proportion and morphology of the hematopoietic tissue in the different groups corresponding to each gestational stage.