University of Aberdeen

About: University of Aberdeen is a education organization based out in Aberdeen, United Kingdom. It is known for research contribution in the topics: Population & Randomized controlled trial. The organization has 21174 authors who have published 49962 publications receiving 2105479 citations. The organization is also known as: Aberdeen University.

Leptin inhibits hypothalamic neurons by activation of ATP-sensitive potassium channels

Abstract: Leptin, the protein encoded by the obese (ob) gene, is secreted from adipose tissue and is thought to act in the central nervous system to regulate food intake and body weight. It has been proposed that leptin acts in the hypothalamus, the main control centre for satiety and energy expenditure. Mutations in leptin or the receptor isoform (Ob-R[L]) present in hypothalamic neurons result in profound obesity and symptoms of non-insulin-dependent diabetes. Here we show that leptin hyperpolarizes glucose-receptive hypothalamic neurons of lean Sprague-Dawley and Zucker rats, but is ineffective on neurons of obese Zucker (fa/fa) rats. This hyperpolarization is due to the activation of a potassium current, and is not easily recovered on removal of leptin, but is reversed by applying the sulphonylurea, tolbutamide. Single-channel recordings demonstrate that leptin activates an ATP-sensitive potassium (K[ATP]) channel. Our data indicate that the K(ATP) channel may function as the molecular end-point of the pathway following leptin activation of the Ob-R(L) receptor in hypothalamic neurons.

The Fungal Cell Wall : Structure, Biosynthesis, and Function

Abstract: The molecular composition of the cell wall is critical for the biology and ecology of each fungal species. Fungal walls are composed of matrix components that are embedded and linked to scaffolds of fibrous load-bearing polysaccharides. Most of the major cell wall components of fungal pathogens are not represented in humans, other mammals, or plants, and therefore the immune systems of animals and plants have evolved to recognize many of the conserved elements of fungal walls. For similar reasons the enzymes that assemble fungal cell wall components are excellent targets for antifungal chemotherapies and fungicides. However, for fungal pathogens, the cell wall is often disguised since key signature molecules for immune recognition are sometimes masked by immunologically inert molecules. Cell wall damage leads to the activation of sophisticated fail-safe mechanisms that shore up and repair walls to avoid catastrophic breaching of the integrity of the surface. The frontiers of research on fungal cell walls are moving from a descriptive phase defining the underlying genes and component parts of fungal walls to more dynamic analyses of how the various components are assembled, cross-linked, and modified in response to environmental signals. This review therefore discusses recent advances in research investigating the composition, synthesis, and regulation of cell walls and how the cell wall is targeted by immune recognition systems and the design of antifungal diagnostics and therapeutics.

Identification of 100 fundamental ecological questions

Abstract: Summary 1. Fundamental ecological research is both intrinsically interesting and provides the basic knowledge required to answer applied questions of importance to the management of the natural world. The 100th anniversary of the British Ecological Society in 2013 is an opportune moment to reflect on the current status of ecology as a science and look forward to high-light priorities for future work.

Subtropical Arctic Ocean temperatures during the Palaeocene/Eocene thermal maximum

Abstract: The Palaeocene/Eocene thermal maximum, ~55 million years ago, was a brief period of widespread, extreme climatic warming1, 2, 3, that was associated with massive atmospheric greenhouse gas input4. Although aspects of the resulting environmental changes are well documented at low latitudes, no data were available to quantify simultaneous changes in the Arctic region. Here we identify the Palaeocene/Eocene thermal maximum in a marine sedimentary sequence obtained during the Arctic Coring Expedition5. We show that sea surface temperatures near the North Pole increased from ~18 °C to over 23 °C during this event. Such warm values imply the absence of ice and thus exclude the influence of ice-albedo feedbacks on this Arctic warming. At the same time, sea level rose while anoxic and euxinic conditions developed in the ocean's bottom waters and photic zone, respectively. Increasing temperature and sea level match expectations based on palaeoclimate model simulations6, but the absolute polar temperatures that we derive before, during and after the event are more than 10 °C warmer than those model-predicted. This suggests that higher-than-modern greenhouse gas concentrations must have operated in conjunction with other feedback mechanisms—perhaps polar stratospheric clouds7 or hurricane-induced ocean mixing8—to amplify early Palaeogene polar temperatures.

The decline of working memory in Alzheimer's disease : A longitudinal study

Abstract: A previous study (Baddeley et al., 1986) explored the hypothesis that patients suffering from dementia of the Alzheimer type (AD) are particularly impaired in the functioning of the central executive component of working memory. It showed that, when patients are required to perform 2 concurrent tasks simultaneously, the AD patients are particularly impaired, even when level of performance on the individual tasks is equated with that of age-matched controls. Although the results were clear, interpretation was still complicated by 2 issues: first, the question of comparability of performance on the separate tests between AD and control patients; secondly, the question of whether our results could be interpreted simply in terms of a limited general processing capacity being more taxed by more difficult dual tasks than by the individual tasks performed alone. The present study followed up the AD and control patients after 6 and 12 mths. We were able to allow for the problem of comparability of performance by using patients as their own control. Under these conditions, there is a very clear tendency for dual task performance to deteriorate while single task performance is maintained. A second experiment varied difficulty within a single task in which patients and controls were required to categorize words as belonging to 1, 2 or 4 semantic categories. There was a clear effect of number of categories on performance and a systematic decline in performance over time. There was, however, no interaction between task difficulty as measured by number of alternatives and rate of deterioration, suggesting that the progressive deterioration in performance shown by AD patients is a function of whether single or dual task performance is required, and is not dependent on simple level of task difficulty. Implications for the analysis of the central executive component of working memory are discussed.