3,313 research outputs found

    Long-distance migration and venting of methane from the base of the hydrate stability zone

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    \ua9 2023, The Author(s).Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world

    Sterol O-Acyltransferase 1 (SOAT1, ACAT) Is a Novel Target of Steroidogenic Factor-1 (SF-1, NR5A1, Ad4BP) in the Human Adrenal

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    Context: Steroidogenic factor-1 (SF-1, NR5A1, Ad4BP) is a master regulator of adrenal development and steroidogenesis. Defects in several known targets of SF-1 can cause adrenal disorders in humans.Objective: We aimed to identify novel targets of SF-1 in the human adrenal. These factors could be important regulators of adrenal development and steroidogenesis and potential candidates for adrenal dysfunction.Design: A gene discovery strategy was developed based on bidirectional manipulation of SF-1. Overexpression or knockdown of SF-1 in NCI-H295R human adrenocortical cells was used to identify a subset of positively-regulated SF-1 targets.Results: This approach identified well-established SF-1 target genes (STAR, CYP11A) and several novel genes (VSNL1, ZIM2, PEG3, SOAT1, and MTSS1). Given its role in cholesterol metabolism, sterol O-acyltransferase 1 (SOAT1, previously referred to as acyl-Coenzyme A: cholesterol acyltransferase 1, ACAT) was studied further and found to be expressed in the developing human fetal adrenal cortex. We hypothesized that impaired SOAT1 activity could result in adrenal insufficiency through reduced cholesteryl ester reserves or through toxic destruction of the adrenal cells during development. Therefore, mutational analysis of SOAT1 in a cohort of 43 patients with unexplained adrenal insufficiency was performed but failed to reveal significant coding sequence changes.Conclusions: Our reverse discovery approach led to the identification of novel SF-1 targets and defined SOAT1 as an important factor in human adrenal steroidogenesis. SF-1-dependent upregulation of SOAT1 may be important for maintaining readily-releasable cholesterol reserves needed for active steroidogenesis and during episodes of recurrent stress. (J Clin Endocrinol Metab 96: E663-E668, 2011

    Erratum: Towards graded-index magnonics: Steering spin waves in magnonic networks [Phys. Rev. B 92, 020408(R) (2015)]

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    This is the final version of the article. Available from the American Physical Societ via the DOI in this record.This is the erratum to 'Towards graded-index magnonics: Steering spin waves in magnonic networks'. Physical Review B 92, 020408(R), 20 July 2015. DOI: https://doi.org/10.1103/PhysRevB.92.020408The article for which this is the erratum is in ORE: http://hdl.handle.net/10871/26167-The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 247556 (NoWaPhen), from the Engineering and Physical Sciences Research Council of the United Kingdom under Projects No. EP/L019876/1 and No. EP/L020696/1, from Russian Science Foundation (Project No. 14-19-00760), and the Scholarship of the President of Russian Federation (SP-313.2015.5)

    Increased Risk of Musculoskeletal Disorders and Mental Health Problems in Retired Professional Jockeys: A Cross-Sectional Study

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    To examine the prevalence of chronic disease and mental health problems in retired professional, male jockeys compared to an age-matched reference population. A cross-sectional study comparing data from a cohort of retired professional jockeys with an age-matched general population sample. Male participants (age range: 50–89 years old) were used to compare health outcomes of self-reported physician-diagnosed conditions: heart disease, stroke, diabetes, hypertension, osteoporosis, osteoarthritis, depression and anxiety between study populations. Conditional logistic regression models were used to estimate associations between study groups and health outcome. In total, 810 participants (135 retired professional male jockeys and 675 participants from the reference population) were included, with an average age of 64.7±9.9 years old. Increased odds of having osteoporosis (OR=6.5, 95%CI 2.1–20.5), osteoarthritis (OR=7.5, 95%CI 4.6–12.2), anxiety (OR=2.8, 95%CI 1.3–5.9) and depression (OR=2.6, 95%CI 1.3–5.7) were seen in the retired professional jockeys. No differences were found for the remaining health outcomes. Retired professional jockeys had increased odds of musculoskeletal disease and mental health problems compared to the general population. Understanding the prevalence of chronic disease and mental health problems in retired professional jockeys will help inform screening and intervention strategies for jockeys

    The influence of minimum sitting period of the ActivPALâ„¢ on the measurement of breaks in sitting in young children

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    Sitting time and breaks in sitting influence cardio-metabolic health. New monitors (e.g. activPALâ„¢) may be more accurate for measurement of sitting time and breaks in sitting although how to optimize measurement accuracy is not yet clear. One important issue is the minimum sitting/upright period (MSUP) to define a new posture. Using the activPALâ„¢, we investigated the effect of variations in MSUP on total sitting time and breaks in sitting, and also determined the criterion validity of different activPALâ„¢ settings for both construct

    Ownership-dependent mating tactics of minor males of the beetle Librodor japonicus (Nitidulidae) with intra-sexual dimorphism of mandibles

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    Intra-sexual dimorphism is found in the weapons of many male beetles. Different behavioral tactics to access females between major and minor males, which adopt fighting and alternative tactics, respectively, are thought to maintain the male dimorphism. In these species major males have enlarged weapons that they use in fights with rival males. Minor males also have small weapons in some of these species, and it is unclear why these males possess weapons. We examined the hypothesis that minor males might adopt a fighting tactic when their status was relatively high in comparison with that of other males (e.g., ownership of a territory). We observed the behavioral tactics of major and minor males of the beetle Librodor japonicus, whose males have a dimorphism of their mandibles. Major males fought for resources, whereas minor males adopted two status-dependent tactics, fighting and sneaking, to access females, depending on their ownership of a sap site. We suggest that ownership status-dependent mating tactics in minor males may maintain the intra-sexual dimorphism in this beetle.</p

    Celecoxib exerts protective effects in the vascular endothelium via COX-2-independent activation of AMPK-CREB-Nrf2 signalling

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    Although concern remains about the athero-thrombotic risk posed by cyclo-oxygenase (COX)-2-selective inhibitors, recent data implicates rofecoxib, while celecoxib appears equivalent to NSAIDs naproxen and ibuprofen. We investigated the hypothesis that celecoxib activates AMP kinase (AMPK) signalling to enhance vascular endothelial protection. In human arterial and venous endothelial cells (EC), and in contrast to ibuprofen and naproxen, celecoxib induced the protective protein heme oxygenase-1 (HO-1). Celecoxib derivative 2,5-dimethyl-celecoxib (DMC) which lacks COX-2 inhibition also upregulated HO-1, implicating a COX-2-independent mechanism. Celecoxib activated AMPKα(Thr172) and CREB-1(Ser133) phosphorylation leading to Nrf2 nuclear translocation. Importantly, these responses were not reproduced by ibuprofen or naproxen, while AMPKα silencing abrogated celecoxib-mediated CREB and Nrf2 activation. Moreover, celecoxib induced H-ferritin via the same pathway, and increased HO-1 and H-ferritin in the aortic endothelium of mice fed celecoxib (1000 ppm) or control chow. Functionally, celecoxib inhibited TNF-α-induced NF-κB p65(Ser536) phosphorylation by activating AMPK. This attenuated VCAM-1 upregulation via induction of HO-1, a response reproduced by DMC but not ibuprofen or naproxen. Similarly, celecoxib prevented IL-1β-mediated induction of IL-6. Celecoxib enhances vascular protection via AMPK-CREB-Nrf2 signalling, a mechanism which may mitigate cardiovascular risk in patients prescribed celecoxib. Understanding NSAID heterogeneity and COX-2-independent signalling will ultimately lead to safer anti-inflammatory drugs

    Amyand's Hernia – Case Report and Review of the Literature

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    Amyand's hernia is an extremely rare condition in which the appendix is positioned in the inguinal hernia sac. Acute appendicitis is much less common in this situation and few reports are found in the literature. We report a case of acute appendicitis with the tip of the appendix incarcerated outside the external ring of the right groin. A mobilized cecum and ascending colon were noticed during surgery. We conducted a review of the literature, emphasizing possible causes and suggesting a predisposing factor for the condition
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