Keele University

About: Keele University is a education organization based out in Newcastle-under-Lyme, United Kingdom. It is known for research contribution in the topics: Population & Stars. The organization has 11318 authors who have published 26323 publications receiving 894671 citations. The organization is also known as: Keele University.

Widespread bacterial populations at glacier beds and their relationship to rock weathering and carbon cycling

Abstract: Bacterial populations found in subglacial meltwaters and basal ice are comparable to those in the active layer of permafrost and orders of magnitude larger than those found in ice cores from large ice sheets. Populations increase with sediment concentration, and 5%–24% of the bacteria are dividing or have just divided, suggesting that the populations are active. These findings (1) support inferences from recent studies of basal ice and meltwater chemistry that microbially mediated redox reactions may be important at glacier beds, (2) challenge the view that chemical weathering in glacial environments arises from purely inorganic reactions, and (3) raise the possibilities that redox reactions are a major source of protons consumed in subglacial weathering and that these reactions may be the dominant proton source beneath ice sheets where meltwaters are isolated from an atmospheric source of CO 2 . Microbial mediation may increase the rate of sulfide oxidation under subglacial conditions, a suggestion supported by the results of simple weathering experiments. If subglacial bacterial populations can oxidize and ferment organic carbon, it is important to reconsider the fate of soil organic carbon accumulated under interglacial conditions in areas subsequently overridden by Pleistocene ice sheets.

Comparison of the Low Dose Short Synacthen Test (1 μg), the Conventional Dose Short Synacthen Test (250 μg), and the Insulin Tolerance Test for Assessment of the Hypothalamo-Pituitary-Adrenal Axis in Patients with Pituitary Disease

Abstract: There is still uncertainty about what is the most appropriate test for assessment of the integrity of the hypothalamo-pituitary-adrenal (HPA) axis. Many advocate the insulin tolerance test (ITT), but this is unpleasant and resource intensive, and may occasionally give misleading results. The conventional [250 μg tetracosactrin, ACTH-(1–24)] short synacthen test (SST) has been used as a simple alternative to the ITT, but it has produced some falsely reassuring results with potentially serious consequences. A low dose [1 μg tetracosactrin, ACTH-(1–24)] short synacthen test (LDSST) has recently been advocated as a more reliable and safer alternative to ITT. Some studies, however, have failed to demonstrate any difference between SST and LDSST. The purpose of this study was to assess the clinical usefulness of LDSST compared to SST and ITT in patients with pituitary disease. We studied 64 patients with suspected or proven pituitary disease. All patients underwent SST and LDSST. Forty-two patients underwent IT...

Senescence in human intervertebral discs

Abstract: Intervertebral discs demonstrate degenerative changes relatively early in life. Disc degeneration, in turn, is associated with back pain and disc herniation, both of which cause considerable clinical problems in the western world. Cell senescence has been linked to degenerative diseases of other connective tissues such as osteoarthritis. Thus we investigated the degree of cell senescence in different regions of discs from patients with different disc disorders. Discs were obtained from 25 patients with disc herniations; from 27 patients undergoing anterior surgery for either back pain due to degenerative disc disease (n = 25) or spondylolisthesis (n = 2) and from six patients with scoliosis. In addition, four discs were obtained post-mortem. Samples were classified as annulus fibrosus or nucleus pulposus and tissue sections were assessed for the degree of cell senescence (using the marker senescence-associated-β-galactosidase (SA-β-Gal)) and the number of cells present in clusters. There were significantly more SA-β-Gal positive cells in herniated discs (8.5% of cells) than those with degenerative disc disease, spondylolisthesis, scoliosis, or cadaveric discs (0.5% of cells; P < 0.001). There was more senescence of cells of the nucleus pulposus compared to those of the annulus fibrosus and in herniated discs a higher proportion of cells in cell clusters (defined as groups of three or more cells) were SA-β-Gal positive (25.5%) compared to cells not in clusters (4.2%, P < 0.0001). This study demonstrates an increased degree of cell senescence in herniated discs, particularly in the nucleus where cell clusters occur. These clusters have been shown previously to form via cell proliferation, which is likely to explain the increased senescence. These findings could have two important clinical implications: firstly, that since senescent cells are known to behave abnormally in other locations, they may lead to deleterious effects on the disc matrix and so contribute to the pathogenesis and secondly, cells from such tissue may not be ideal for cell therapy and repair via tissue engineering.