529 research outputs found

    Study on the influence of different error sources on sky radiance measurements and inversion-derived aerosol products in the frame of AERONET

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    Comunicación presentada en: 2012 European Aerosol Conference (EAC-2012), B-WG01S2P30, celebrada del 2 al 7 de septiembre de 2012 en Granada.Financial support from the Spanish MICINN under projects with ref. CGL2009-09740, CGL2011-23413, CGL2010-09480-E and CGL2011-13085-E is gratefully acknowledged

    The pH of the skin surface and its impact on the barrier function

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    The `acid mantle' of the stratum corneum seems to be important for both permeability barrier formation and cutaneous antimicrobial defense. However, the origin of the acidic pH, measurable on the skin surface, remains conjectural. Passive and active influencing factors have been proposed, e. g. eccrine and sebaceous secretions as well as proton pumps. In recent years, numerous investigations have been published focusing on the changes in the pH of the deeper layers of the stratum corneum, as well as on the influence of physiological and pathological factors. The pH of the skin follows a sharp gradient across the stratum corneum, which is suspected to be important in controlling enzymatic activities and skin renewal. The skin pH is affected by a great number of endogenous factors, e. g. skin moisture, sweat, sebum, anatomic site, genetic predisposition and age. In addition, exogenous factors like detergents, application of cosmetic products, occlusive dressings as well as topical antibiotics may influence the skin pH. Changes in the pH are reported to play a role in the pathogenesis of skin diseases like irritant contact dermatitis, atopic dermatitis, ichthyosis, acne vulgaris and Candida albicans infections. Therefore, the use of skin cleansing agents, especially synthetic detergents with a pH of about 5.5, may be of relevance in the prevention and treatment of those skin diseases. Copyright (c) 2006 S. Karger AG, Base

    Dealing with Food and Eggs in Mouthbrooding Cichlids: Structural and Functional Trade-Offs in Fitness Related Traits

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    As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species.Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus) and a "biter" (H. fischeri). The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs.Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two studied haplochromine cichlids, stressing the importance of including species-specific information at the gender level when addressing interspecific functional/morphological differences

    Nucleolin, a Shuttle Protein Promoting Infection of Human Monocytes by Francisella tularensis

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    International audienceWe herein confirm the importance of nucleolin expression for LVS binding and its specificity as nucleolin is not involved in binding of another intracellular pathogen as L. monocytogenes or an inert particle. Association of nucleolin with F. tularensis during infection continues intracellularly after endocytosis of the bacteria. The present work therefore unravels for the first time the presence of nucleolin in the phagosomal compartment of macrophages

    Velocity tuning of friction with two trapped atoms

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    Our ability to control friction remains modest, as our understanding of the underlying microscopic processes is incomplete. Atomic force experiments have provided a wealth of results on the dependence of nanofriction on structure velocity and temperature but limitations in the dynamic range, time resolution, and control at the single-atom level have hampered a description from first principles. Here, using an ion-crystal system with single-atom, single-substrate-site spatial and single-slip temporal resolution we measure the friction force over nearly five orders of magnitude in velocity, and contiguously observe four distinct regimes, while controlling temperature and dissipation. We elucidate the interplay between thermal and structural lubricity for two coupled atoms, and provide a simple explanation in terms of the Peierls–Nabarro potential. This extensive control at the atomic scale enables fundamental studies of the interaction of many-atom surfaces, possibly into the quantum regime

    Deleterious variants in TRAK1 disrupt mitochondrial movement and cause fatal encephalopathy

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    This is the author accepted manuscript. The final version is available from Oxford University Press via the DOI in this record.The corrigendum to this article is in ORE: http://hdl.handle.net/10871/33588Cellular distribution and dynamics of mitochondria are regulated by several motor proteins and a microtubule network. In neurons, mitochondrial trafficking is crucial because of high energy needs and calcium ion buffering along axons to synapses during neurotransmission. The trafficking kinesin proteins (TRAKs) are well characterized for their role in lysosomal and mitochondrial trafficking in cells, especially neurons. Using whole exome sequencing, we identified homozygous truncating variants in TRAK1 (NM_001042646:c.287-2A > C), in six lethal encephalopathic patients from three unrelated families. The pathogenic variant results in aberrant splicing and significantly reduced gene expression at the RNA and protein levels. In comparison with normal cells, TRAK1-deficient fibroblasts showed irregular mitochondrial distribution, altered mitochondrial motility, reduced mitochondrial membrane potential, and diminished mitochondrial respiration. This study confirms the role of TRAK1 in mitochondrial dynamics and constitutes the first report of this gene in association with a severe neurodevelopmental disorder.D.M.E. and J.K. are supported by the Office of Naval Research (ONR) Grant N000141410538. M.S. is supported by the BBSRC (BB/K006231/1), a Wellcome Trust Institutional Strategic Support Award (WT097835MF, WT105618MA), and a Marie Curie Initial Training Network (ITN) action PerFuMe (316723). M.C.V.M., J.S., H.P., C.F., T.V. and W.A.G. are supported by the NGHRI Intramural Research Program. G.R. is supported by the Kahn Family Foundation and the Israeli Centers of Excellence (I-CORE) Program (ISF grant no. 41/11)

    Impaired complex I repair causes recessive Leber's hereditary optic neuropathy

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    Leber's hereditary optic neuropathy (LHON) is the most frequent mitochondrial disease and was the first to be genetically defined by a point mutation in mitochondrial DNA (mtDNA). A molecular diagnosis is achieved in up to 95% of cases, the vast majority of which are accounted for by 3 mutations within mitochondrial complex I subunit-encoding genes in the mtDNA (mtLHON). Here, we resolve the enigma of LHON in the absence of pathogenic mtDNA mutations. We describe biallelic mutations in a nuclear encoded gene, DNAJC30, in 33 unsolved patients from 29 families and establish an autosomal recessive mode of inheritance for LHON (arLHON), which to date has been a prime example of a maternally inherited disorder. Remarkably, all hallmarks of mtLHON were recapitulated, including incomplete penetrance, male predominance, and significant idebenone responsivity. Moreover, by tracking protein turnover in patient-derived cell lines and a DNAJC30-knockout cellular model, we measured reduced turnover of specific complex I N-module subunits and a resultant impairment of complex I function. These results demonstrate that DNAJC30 is a chaperone protein needed for the efficient exchange of complex I subunits exposed to reactive oxygen species and integral to a mitochondrial complex I repair mechanism, thereby providing the first example to our knowledge of a disease resulting from impaired exchange of assembled respiratory chain subunits

    Increased p53 immunopositivity in anaplastic medulloblastoma and supratentorial PNET is not caused by JC virus

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    BACKGROUND: p53 mutations are relatively uncommon in medulloblastoma, but abnormalities in this cell cycle pathway have been associated with anaplasia and worse clinical outcomes. We correlated p53 protein expression with pathological subtype and clinical outcome in 75 embryonal brain tumors. The presence of JC virus, which results in p53 protein accumulation, was also examined. METHODS: p53 protein levels were evaluated semi-quantitatively in 64 medulloblastomas, 3 atypical teratoid rhabdoid tumors (ATRT), and 8 supratentorial primitive neuroectodermal tumors (sPNET) using immunohistochemistry. JC viral sequences were analyzed in DNA extracted from 33 frozen medulloblastoma and PNET samples using quantitative polymerase chain reaction. RESULTS: p53 expression was detected in 18% of non-anaplastic medulloblastomas, 45% of anaplastic medulloblastomas, 67% of ATRT, and 88% of sPNET. The increased p53 immunoreactivity in anaplastic medulloblastoma, ATRT, and sPNET was statistically significant. Log rank analysis of clinical outcome revealed significantly shorter survival in patients with p53 immunopositive embryonal tumors. No JC virus was identified in the embryonal brain tumor samples, while an endogenous human retrovirus (ERV-3) was readily detected. CONCLUSION: Immunoreactivity for p53 protein is more common in anaplastic medulloblastomas, ATRT and sPNET than in non-anaplastic tumors, and is associated with worse clinical outcomes. However, JC virus infection is not responsible for increased levels of p53 protein

    Pathological variants in TOP3A cause distinct disorders of mitochondrial and nuclear genome stability

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    Topoisomerase 3α (TOP3A) is an enzyme that removes torsional strain and interlinks between DNA molecules. TOP3A localises to both the nucleus and mitochondria, with the two isoforms playing specialised roles in DNA recombination and replication respectively. Pathogenic variants in TOP3A can cause a disorder similar to Bloom syndrome, which results from bi-allelic pathogenic variants in BLM, encoding a nuclear-binding partner of TOP3A. In this work, we describe 11 individuals from 9 families with an adult-onset mitochondrial disease resulting from bi-allelic TOP3A gene variants. The majority of patients have a consistent clinical phenotype characterised by bilateral ptosis, ophthalmoplegia, myopathy and axonal sensory-motor neuropathy. We present a comprehensive characterisation of the effect of TOP3A variants, from individuals with mitochondrial disease and Bloom-like syndrome, upon mtDNA maintenance and different aspects of enzyme function. Based on these results, we suggest a model whereby the overall severity of the TOP3A catalytic defect determines the clinical outcome, with milder variants causing adult-onset mitochondrial disease and more severe variants causing a Bloom-like syndrome with mitochondrial dysfunction in childhood
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