1,926 research outputs found

    The Neurobiological Impact of Ghrelin Suppression after Oesophagectomy

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    Ghrelin, discovered in 1999, is a 28-amino-acid hormone, best recognized as a stimulator of growth hormone secretion, but with pleiotropic functions in the area of energy homeostasis, such as appetite stimulation and energy expenditure regulation. As the intrinsic ligand of the growth hormone secretagogue receptor (GHS-R), ghrelin appears to have a broad array of effects, but its primary role is still an area of debate. Produced mainly from oxyntic glands in the stomach, but with a multitude of extra-metabolic roles, ghrelin is implicated in complex neurobiological processes. Comprehensive studies within the areas of obesity and metabolic surgery have clarified the mechanism of these operations. As a stimulator of growth hormone (GH), and an apparent inducer of positive energy balance, other areas of interest include its impact on carcinogenesis and tumour proliferation and its role in the cancer cachexia syndrome. This has led several authors to study the hormone in the cancer setting. Ghrelin levels are acutely reduced following an oesophagectomy, a primary treatment modality for oesophageal cancer. We sought to investigate the nature of this postoperative ghrelin suppression, and its neurobiological implications

    Variations in 24-mu m morphologies among galaxies in the Spitzer Infrared Nearby Galaxies Survey: new insights into the Hubble sequence

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    To study the distribution of star formation and dust emission within nearby galaxies, we measured five morphological parameters in the 3.6- and 24-μm wavebands for 65 galaxies in the Spitzer Infrared Nearby Galaxies Survey (SINGS) and eight galaxies that were serendipitously observed by SINGS. The morphological parameters demonstrate strong variations along the Hubble sequence, including statistically significant differences between S0/a-Sab and Sc-Sd galaxies. Early-type galaxies are generally found to be compact, centralized, symmetric sources in the 24-μm band, while late-type galaxies are generally found to be extended, asymmetric sources. These results suggest that the processes that increase the real or apparent sizes of galaxies\u27 bulges also lead to more centralized 24-μm dust emission. Several phenomena, such as strong nuclear star formation, Seyfert activity, or outer ring structures, may cause galaxies to deviate from the general morphological trends observed at 24 μm. We also note that the 24-μm morphologies of Sdm-Im galaxies are quite varied, with some objects appearing very compact and symmetric but others appearing diffuse and asymmetric. These variations reflect the wide variation in star formation in irregular galaxies as observed at other wavelengths. The variations in the 24-μm morphological parameters across the Hubble sequence mirror many of the morphological trends seen in other tracers of the ISM and in stellar emission. However, the 24-μm morphological parameters for the galaxies in this sample do not match the morphological parameters measured in the stellar wavebands. This implies that the distribution of dust emission is related to but not equivalent to the distribution of stellar emission

    A lineage-specific rapid diagnostic test (Chagas Sero K-SeT) identifies Brazilian Trypanosoma cruzi II/V/VI reservoir hosts among diverse mammalian orders.

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    Trypanosoma cruzi, the protozoan agent of Chagas disease in the Americas, is comprised of six genetic lineages (TcI-TcVI) and a possible seventh (TcBat, related to TcI). Identification of T. cruzi lineages infecting reservoir mammalian species is fundamental to resolving transmission cycles. However, this is hindered by the limited sensitivity and technical complexity of parasite isolation and genotyping. An alternative approach is serology using T. cruzi lineage-specific epitopes, such as those of the trypomastigote small surface antigen (TSSA). For surveillance of T. cruzi lineage infections in mammal species from diverse Brazilian regions, we apply a novel rapid diagnostic test (RDT, Chagas Sero K-SeT), which incorporates the TSSA peptide epitope specific to TcII/V/VI (TSSApep-II/V/VI) and Protein G detection of antibodies. Chagas Sero K-SeT RDT results with sera from experimentally infected mice, from tamarin primates (Leontopithecus spp.) and from canines (Canis familiaris) were concordant with corresponding TSSApep-II/V/VI ELISAs. The Chagas Sero K-Set detected TcII/V/VI infections in Leontopithecus spp. from the Atlantic forest (n = 46), in C. familiaris (n = 16) and Thrichomys laurentius (n = 2) from Caatinga biome and Chiroptera (n = 1) from Acre, Amazonia. The Chagas Sero K-SeT RDT is directly applicable to TcII/V/VI-specific serological surveillance of T. cruzi infection in several different mammalian Orders. It can replace ELISAs and provides efficient, point-of-sampling, low-cost detection of TcII/V/VI infections, with at least equivalent sensitivity, although some mammals may be difficult to trap, and, not unexpectedly, Chagas Sero K-SeT could not recognise feline IgG. Knowledge of sylvatic hosts of T. cruzi can be expanded, new reservoir species discovered, and the ecology of transmission cycles clarified, particularly with adaptation to further mammalian Orders

    Benign mesenteric lymphangioma presenting as acute pancreatitis: a case report

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    Benign mesenteric lymphangiomas are rare intra-abdominal cysts which may be asymptomatic or present with a variety of abdominal symptoms including an acute abdomen. We are however not aware of any reports in the literature linking mesenteric lymphangioma to acute pancreatitis. We present the case of a 62-year-old man who was admitted with signs and symptoms of acute pancreatitis and a palpable abdominal mass. Computerised tomography (CT) of his abdomen confirmed the presence of a mesenteric cystic mass. He underwent a laparotomy at which a large thin walled mass filled with a chylous fluid was resected. Histological analysis of this cyst showed it to be a benign mesenteric lymphangioma

    Lysine-91 of the tetraheme c-type cytochrome CymA is essential for quinone interaction and arsenate respiration in Shewanella sp. strain ANA-3

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    The tetraheme c-type cytochrome, CymA, is essential for arsenate respiratory reduction in Shewanella sp. ANA-3, a model arsenate reducer. CymA is predicted to mediate electron transfer from quinols to the arsenate respiratory reductase (ArrAB). Here, we present biochemical and physiological evidence that CymA interacts with menaquinol (MQH2) substrates. Fluorescence quench titration with the MQH2 analog, 2-n-heptyl-4-hydroxyquinoline-N-oxide (HOQNO), was used to demonstrate quinol binding of E. coli cytoplasmic membranes enriched with various forms of CymA. Wild-type CymA bound HOQNO with a Kd of 0.1–1 μM. It was also shown that the redox active MQH2 analog, 2,3-dimethoxy-1,4-naphthoquinone (DMNH2), could reduce CymA in cytoplasmic membrane preparations. Based on a CymA homology model made from the NrfH tetraheme cytochrome structure, it was predicted that Lys91 would be involved in CymA-quinol interactions. CymA with a K91Q substitution showed little interaction with HOQNO. In addition, DMNH2-dependent reduction of CymA-K91Q was diminished by 45% compared to wild-type CymA. A ΔcymA ANA-3 strain containing a plasmid copy of cymA-K91Q failed to grow with arsenate as an electron acceptor. These results suggest that Lys91 is physiologically important for arsenate respiration and support the hypothesis that CymA interacts with menaquinol resulting in the reduction of the cytochrome

    Closed-loop separation control over a sharp edge ramp using Genetic Programming

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    We experimentally perform open and closed-loop control of a separating turbulent boundary layer downstream from a sharp edge ramp. The turbulent boundary layer just above the separation point has a Reynolds number Reθ3500Re_{\theta}\approx 3\,500 based on momentum thickness. The goal of the control is to mitigate separation and early re-attachment. The forcing employs a spanwise array of active vortex generators. The flow state is monitored with skin-friction sensors downstream of the actuators. The feedback control law is obtained using model-free genetic programming control (GPC) (Gautier et al. 2015). The resulting flow is assessed using the momentum coefficient, pressure distribution and skin friction over the ramp and stereo PIV. The PIV yields vector field statistics, e.g. shear layer growth, the backflow area and vortex region. GPC is benchmarked against the best periodic forcing. While open-loop control achieves separation reduction by locking-on the shedding mode, GPC gives rise to similar benefits by accelerating the shear layer growth. Moreover, GPC uses less actuation energy.Comment: 24 pages, 24 figures, submitted to Experiments in Fluid

    A Spatial Analysis of Rift Valley Fever Virus Seropositivity in Domestic Ruminants in Tanzania

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    Rift Valley fever (RVF) is an acute arthropod-borne viral zoonotic disease primarily occurring in Africa. Since RVF-like disease was reported in Tanzania in 1930, outbreaks of the disease have been reported mainly from the eastern ecosystem of the Great Rift Valley. This cross-sectional study was carried out to describe the variation in RVF virus (RVFV) seropositivity in domestic ruminants between selected villages in the eastern and western Rift Valley ecosystems in Tanzania, and identify potential risk factors. Three study villages were purposively selected from each of the two Rift Valley ecosystems. Serum samples from randomly selected domestic ruminants (n = 1,435) were tested for the presence of specific immunoglobulin G (IgG) and M (IgM), using RVF enzyme-linked immunosorbent assay methods. Mixed effects logistic regression modelling was used to investigate the association between potential risk factors and RVFV seropositivity. The overall RVFV seroprevalence (n = 1,435) in domestic ruminants was 25.8% and species specific seroprevalence was 29.7%, 27.7% and 22.0% in sheep (n = 148), cattle (n = 756) and goats (n = 531), respectively. The odds of seropositivity were significantly higher in animals sampled from the villages in the eastern than those in the western Rift Valley ecosystem (OR = 1.88, CI: 1.41, 2.51; p<0.001), in animals sampled from villages with soils of good than those with soils of poor water holding capacity (OR = 1.97; 95% CI: 1.58, 3.02; p< 0.001), and in animals which had been introduced than in animals born within the herd (OR = 5.08, CI: 2.74, 9.44; p< 0.001). Compared with animals aged 1-2 years, those aged 3 and 4-5 years had 3.40 (CI: 2.49, 4.64; p< 0.001) and 3.31 (CI: 2.27, 4.82, p< 0.001) times the odds of seropositivity. The findings confirm exposure to RVFV in all the study villages, but with a higher prevalence in the study villages from the eastern Rift Valley ecosystem
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