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  • 1
    Publication Date: 2018-12-14
    Description: Paired measurements of 14 C/ 12 C and 230 Th ages from two Hulu Cave stalagmites complete a precise record of atmospheric 14 C covering the full range of the 14 C dating method (~54,000 years). Over the last glacial period, atmospheric 14 C/ 12 C ranges from values similar to modern values to values 1.70 times higher (42,000 to 39,000 years ago). The latter correspond to 14 C ages 5200 years less than calibrated ages and correlate with the Laschamp geomagnetic excursion followed by Heinrich Stadial 4. Millennial-scale variations are largely attributable to Earth’s magnetic field changes and in part to climate-related changes in the oceanic carbon cycle. A progressive shift to lower 14 C/ 12 C values between 25,000 and 11,000 years ago is likely related, in part, to progressively increasing ocean ventilation rates.
    Keywords: Atmospheric Science, Geochemistry, Geophysics
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2018-10-26
    Description: The separation of ethane from its corresponding ethylene is an important, challenging, and energy-intensive process in the chemical industry. Here we report a microporous metal-organic framework, iron(III) peroxide 2,5-dioxido-1,4-benzenedicarboxylate [Fe 2 (O 2 )(dobdc) (dobdc 4– : 2,5-dioxido-1,4-benzenedicarboxylate)], with iron (Fe)–peroxo sites for the preferential binding of ethane over ethylene and thus highly selective separation of C 2 H 6 /C 2 H 4 . Neutron powder diffraction studies and theoretical calculations demonstrate the key role of Fe-peroxo sites for the recognition of ethane. The high performance of Fe 2 (O 2 )(dobdc) for the ethane/ethylene separation has been validated by gas sorption isotherms, ideal adsorbed solution theory calculations, and simulated and experimental breakthrough curves. Through a fixed-bed column packed with this porous material, polymer-grade ethylene (99.99% pure) can be straightforwardly produced from ethane/ethylene mixtures during the first adsorption cycle, demonstrating the potential of Fe 2 (O 2 )(dobdc) for this important industrial separation with a low energy cost under ambient conditions.
    Keywords: Chemistry, Materials Science
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Geosciences , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2018-01-03
    Description: Since its emergence in 2013, the H7N9 low-pathogenic avian influenza virus (LPAIV) has been circulating in domestic poultry in China, causing five waves of human infections. A novel H7N9 highly pathogenic avian influenza virus (HPAIV) variant possessing multiple basic amino acids at the cleavage site of the hemagglutinin (HA) protein was first reported in two cases of human infection in January 2017. More seriously, those novel H7N9 HPAIV variants have been transmitted and caused outbreaks on poultry farms in eight provinces in China. Herein, we demonstrate the presence of three different amino acid motifs at the cleavage sites of these HPAIV variants which were isolated from chickens and humans and likely evolved from the preexisting LPAIVs. Animal experiments showed that these novel H7N9 HPAIV variants are both highly pathogenic in chickens and lethal to mice. Notably, human-origin viruses were more pathogenic in mice than avian viruses, and the mutations in the PB2 gene associated with adaptation to mammals (E627K, A588V, and D701N) were identified by next-generation sequencing (NGS) and Sanger sequencing of the isolates from infected mice. No polymorphisms in the key amino acid substitutions of PB2 and HA in isolates from infected chicken lungs were detected by NGS. In sum, these results highlight the high degree of pathogenicity and the valid transmissibility of this new H7N9 variant in chickens and the quick adaptation of this new H7N9 variant to mammals, so the risk should be evaluated and more attention should be paid to this variant. IMPORTANCE Due to the recent increased numbers of zoonotic infections in poultry and persistent human infections in China, influenza A(H7N9) virus has remained a public health threat. Most of the influenza A(H7N9) viruses reported previously have been of low pathogenicity. Now, these novel H7N9 HPAIV variants have caused human infections in three provinces and outbreaks on poultry farms in eight provinces in China. We analyzed the molecular features and compared the relative characteristics of one H7N9 LPAIV and two H7N9 HPAIVs isolated from chickens and two human-origin H7N9 HPAIVs in chicken and mouse models. We found that all HPAIVs both are highly pathogenic and have valid transmissibility in chickens. Strikingly, the human-origin viruses were more highly pathogenic than the avian-origin viruses in mice, and dynamic mutations were confirmed by NGS and Sanger sequencing. Our findings offer important insight into the origin, adaptation, pathogenicity, and transmissibility of these viruses to both poultry and mammals.
    Print ISSN: 0022-538X
    Electronic ISSN: 1098-5514
    Topics: Medicine
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  • 4
    Publication Date: 2018-02-09
    Description: Intra-abdominal adhesion is a common complication after laparotomy. Conventional therapeutic strategies still cannot safely and effectively prevent this disorder. In this study, a combination of chitosan, cellulose, and seaweed polysaccharide (thereafter referred as CCS) was developed to significantly alleviate the formation of postoperative adhesion in rats with abdominal trauma. Transforming growth factor β 1 (TGF- β 1, an important promoter of fibrosis) and its downstream factors—namely, alpha-smooth muscle actin and plasminogen activator inhibitor-1 (PAI-1)—were effectively suppressed by CCS in vivo, and as a result, the activation of tissue plasminogen activator (tPA, may generate plasmin that is a fibrinolytic factor capable of breaking down fibrin) was significantly promoted, presenting antifibrosis effects of CCS. In addition, the activity of kinases [e.g., transforming growth factor–activated kinase 1 (TAK1), c-Jun N-terminal kinase (JNK)/Stress-activated Protein Kinase (SAPK), and p38] in the mitogen-activated protein kinase (MAPK) inflammation signaling pathway was also significantly suppressed by CCS in vivo, demonstrating anti-inflammatory functions of CCS. The histologic studies further confirmed the role of CCS in the inhibition of fibrosis, collagen deposition, inflammation, and vascular proliferation. These results indicate the clinical potential of CCS in the treatment of postoperative intra-abdominal adhesion. CCS may induce both antifibrosis and anti-inflammatory effects, potentially inhibiting the postoperative intra-abdominal adhesion. For antifibrosis effects, the expression of PAI-1 (a key factor for the adhesion formation) can be regulated by different TGF- β 1–associated signaling pathways, such as the Smads/p53 pathway, metalloproteinase/tissue inhibitor of matrix metalloproteinases pathway, Mitogen-activated Extracellular signal-regulated Kinase (MEK)/extracellular regulated protein kinase (ERK) pathway, and Yes-associated protein/transcriptional coactivator with PDZ-binding motif pathway. Following the downregulation of PAI-1 achieved by CCS, the activation of tPA (which may generate plasmin that is a fibrinolytic factor capable of breaking down fibrin) is significantly promoted. For anti-inflammation effects, CCS may suppress the phosphorylation of classic kinases (e.g., TAK1, JNK, and p38) in the MAPK signaling pathway. In addition to the MAPK pathway, inflammatory pathways, such as Nuclear Factor--gene Binding(NF-B), MEK/ERK, and Ras homologue protein/Rho associated coiled coil forming protein, are associated with the formation of intra-abdominal adhesion. Therefore, the prevention mechanisms of CCS will be further investigated in the future, with a hope of fully understanding of antiadhesion effects.
    Print ISSN: 0022-3565
    Electronic ISSN: 1521-0103
    Topics: Medicine
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  • 5
    Publication Date: 2018-01-19
    Description: Ferritin turnover plays a major role in tissue iron homeostasis, and ferritin malfunction is associated with impaired iron homeostasis and neurodegenerative diseases. In most eukaryotes, ferritin is considered an intracellular protein that stores iron in a nontoxic and bioavailable form. In insects, ferritin is a classically secreted protein and plays a major role in systemic iron distribution. Mammalian ferritin lacks the signal peptide for classical endoplasmic reticulum–Golgi secretion but is found in serum and is secreted via a nonclassical lysosomal secretion pathway. This study applied bioinformatics and biochemical tools, alongside a protein trafficking mouse models, to characterize the mechanisms of ferritin secretion. Ferritin trafficking via the classical secretion pathway was ruled out, and a 2:1 distribution of intracellular ferritin between membrane-bound compartments and the cytosol was observed, suggesting a role for ferritin in the vesicular compartments of the cell. Focusing on nonclassical secretion, we analyzed mouse models of impaired endolysosomal trafficking and found that ferritin secretion was decreased by a BLOC-1 mutation but increased by BLOC-2, BLOC-3, and Rab27A mutations of the cellular trafficking machinery, suggesting multiple export routes. A 13-amino-acid motif unique to ferritins that lack the secretion signal peptide was identified on the BC-loop of both subunits and plays a role in the regulation of ferritin secretion. Finally, we provide evidence that secretion of iron-rich ferritin was mediated via the multivesicular body–exosome pathway. These results enhance our understanding of the mechanism of ferritin secretion, which is an important piece in the puzzle of tissue iron homeostasis.
    Keywords: Red Cells, Iron, and Erythropoiesis
    Print ISSN: 0006-4971
    Electronic ISSN: 1528-0020
    Topics: Biology , Medicine
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  • 6
    Publication Date: 2018-01-23
    Description: Aims To validate the Singapore nomogram for outcome prediction in breast phyllodes tumours in a large cohort of Singaporean patients, as previous validation studies were conducted on small numbers of patients. We also investigate the association of fibroadenomas and phyllodes tumours within a subset of our cohort. Methods Histological parameters, surgical margin status and clinical follow-up data of 259 women diagnosed with phyllodes tumours were analysed. Patients with concurrent malignant or premalignant disease were excluded from the validation to minimise confounding influences. Biostatistics modelling was performed, and the concordance between predicted and observed survivals was calculated. The association between fibroadenomas and phyllodes tumours was quantified in a subset of the women. Results Phyllodes tumours with higher number of mitoses, stromal overgrowth and positive surgical margins were found to be associated with greater risk of clinical recurrence. Patients with a higher nomogram score had a significantly higher risk of developing relapse. Forty out of 78 (51.3%) of the subset of phyllodes cases reviewed showed either fibroadenoma-like areas within the phyllodes tumours or concurrent fibroadenomas in the ipsilateral or contralateral breast. Conclusions The Singapore nomogram is useful in predicting outcome in breast phyllodes tumours when applied to a large cohort of Singaporean women.
    Print ISSN: 0021-9746
    Electronic ISSN: 1472-4146
    Topics: Medicine
    Published by BMJ Publishing Group
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  • 7
    Publication Date: 2018-02-10
    Description: Histone acetylation is associated with active transcription in eukaryotic cells. It helps to open up the chromatin by neutralizing the positive charge of histone lysine residues and providing binding platforms for "reader" proteins. The bromodomain (BRD) has long been thought to be the sole protein module that recognizes acetylated histones. Recently, we identified the YEATS domain of AF9 (ALL1 fused gene from chromosome 9) as a novel acetyl-lysine-binding module and showed that the ENL (eleven-nineteen leukemia) YEATS domain is an essential acetyl-histone reader in acute myeloid leukemias. The human genome encodes four YEATS domain proteins, including GAS41, a component of chromatin remodelers responsible for H2A.Z deposition onto chromatin; however, the importance of the GAS41 YEATS domain in human cancer remains largely unknown. Here we report that GAS41 is frequently amplified in human non-small cell lung cancer (NSCLC) and is required for cancer cell proliferation, survival, and transformation. Biochemical and crystal structural studies demonstrate that GAS41 binds to histone H3 acetylated on H3K27 and H3K14, a specificity that is distinct from that of AF9 or ENL. ChIP-seq (chromatin immunoprecipitation [ChIP] followed by high-throughput sequencing) analyses in lung cancer cells reveal that GAS41 colocalizes with H3K27ac and H3K14ac on the promoters of actively transcribed genes. Depletion of GAS41 or disruption of the interaction between its YEATS domain and acetylated histones impairs the association of histone variant H2A.Z with chromatin and consequently suppresses cancer cell growth and survival both in vitro and in vivo. Overall, our study identifies GAS41 as a histone acetylation reader that promotes histone H2A.Z deposition in NSCLC.
    Print ISSN: 0890-9369
    Topics: Biology
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  • 8
    Publication Date: 2018-05-15
    Description: The primate lentiviral accessory protein Nef downregulates CD4 and major histocompatibility complex class I (MHC-I) from the cell surface via independent endosomal trafficking pathways to promote viral pathogenesis. In addition, Nef antagonizes a novel restriction factor, SERINC5 (Ser5), to increase viral infectivity. To explore the molecular mechanism of Ser5 antagonism by Nef, we determined how Nef affects Ser5 expression and intracellular trafficking in comparison to CD4 and MHC-I. We confirm that Nef excludes Ser5 from human immunodeficiency virus type 1 (HIV-1) virions by downregulating its cell surface expression via similar functional motifs required for CD4 downregulation. We find that Nef decreases both Ser5 and CD4 expression at steady-state levels, which are rescued by NH 4 Cl or bafilomycin A1 treatment. Nef binding to Ser5 was detected in living cells using a bimolecular fluorescence complementation assay, where Nef membrane association is required for interaction. In addition, Nef triggers rapid Ser5 internalization via receptor-mediated endocytosis and relocalizes Ser5 to Rab5 + early, Rab7 + late, and Rab11 + recycling endosomes. Manipulation of AP-2, Rab5, Rab7, and Rab11 expression levels affects the Nef-dependent Ser5 and CD4 downregulation. Moreover, although Nef does not promote Ser5 polyubiquitination, Ser5 downregulation relies on the ubiquitination pathway, and both K48- and K63-specific ubiquitin linkages are required for the downregulation. Finally, Nef promotes Ser5 colocalization with LAMP1, which is enhanced by bafilomycin A1 treatment, suggesting that Ser5 is targeted to lysosomes for destruction. We conclude that Nef uses a similar mechanism to downregulate Ser5 and CD4, which sorts Ser5 into a point-of-no-return degradative pathway to counteract its restriction. IMPORTANCE Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) express an accessory protein called Nef to promote viral pathogenesis. Nef drives immune escape in vivo through downregulation of CD4 and MHC-I from the host cell surface. Recently, Nef was reported to counteract a novel host restriction factor, Ser5, to increase viral infectivity. Nef downregulates cell surface Ser5, thus preventing its incorporation into virus particles, resulting in disruption of its antiviral activity. Here, we report mechanistic studies of Nef-mediated Ser5 downregulation in comparison to CD4 and MHC-I. We demonstrate that Nef binds directly to Ser5 in living cells and that Nef-Ser5 interaction requires Nef association with the plasma membrane. Subsequently, Nef internalizes Ser5 from the plasma membrane via receptor-mediated endocytosis, and targets ubiquitinated Ser5 to endosomes and lysosomes for destruction. Collectively, these results provide new insights into our ongoing understanding of the Nef-Ser5 arms race in HIV-1 infection.
    Print ISSN: 0022-538X
    Electronic ISSN: 1098-5514
    Topics: Medicine
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  • 9
    Publication Date: 2018-05-15
    Description: H7N9 virus has caused five infection waves since it emerged in 2013. The highest number of human cases was seen in wave 5; however, the underlying reasons have not been thoroughly elucidated. In this study, the geographical distribution, phylogeny, and genetic evolution of 240 H7N9 viruses in wave 5, including 35 new isolates from patients and poultry in nine provinces, were comprehensively analyzed together with strains from first four waves. Geographical distribution analysis indicated that the newly emerging highly pathogenic (HP) and low-pathogenicity (LP) H7N9 viruses were cocirculating, causing human and poultry infections across China. Genetic analysis indicated that dynamic reassortment of the internal genes among LP-H7N9/H9N2/H6Ny and HP-H7N9, as well as of the surface genes, between the Yangtze and Pearl River Delta lineages resulted in at least 36 genotypes, with three major genotypes (G1 [A/chicken/Jiangsu/SC537/2013-like], G3 [A/Chicken/Zhongshan/ZS/2017-like], and G11 [A/Anhui/40094/2015-like]). The HP-H7N9 genotype likely evolved from G1 LP-H7N9 by the insertion of a KRTA motif at the cleavage site (CS) and then evolved into 15 genotypes with four different CS motifs, including PKG KRTA R/G, PKG KRIA R/G, PKR KRAA R/G, and PKR KRTA R/G. Approximately 46% (28/61) of HP strains belonged to G3. Importantly, neuraminidase (NA) inhibitor (NAI) resistance (R292K in NA) and mammalian adaptation (e.g., E627K and A588V in PB2) mutations were found in a few non-human-derived HP-H7N9 strains. In summary, the enhanced prevalence and diverse genetic characteristics that occurred with mammalian-adapted and NAI-resistant mutations may have contributed to increased numbers of human infections in wave 5. IMPORTANCE The highest numbers of human H7N9 infections were observed during wave 5 from October 2016 to September 2017. Our results showed that HP-H7N9 and LP-H7N9 had spread virtually throughout China and underwent dynamic reassortment with different subtypes (H7N9/H9N2 and H6Ny) and lineages (Yangtze and Pearl River Delta lineages), resulting in totals of 36 and 3 major genotypes, respectively. Notably, the NAI drug-resistant (R292K in NA) and mammalian-adapted (e.g., E627K in PB2) mutations were found in HP-H7N9 not only from human isolates but also from poultry and environmental isolates, indicating increased risks for human infections. The broad dissemination of LP- and HP-H7N9 with high levels of genetic diversity and host adaptation and drug-resistant mutations likely accounted for the sharp increases in the number of human infections during wave 5. Therefore, more strategies are needed against the further spread and damage of H7N9 in the world.
    Print ISSN: 0022-538X
    Electronic ISSN: 1098-5514
    Topics: Medicine
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  • 10
    Publication Date: 2018-03-29
    Description: The group of highly related avian leukosis viruses (ALVs) in chickens are thought to have evolved from a common retroviral ancestor into six subgroups, A to E and J. These ALV subgroups use diverse cellular proteins encoded by four genetic loci in chickens as receptors to gain entry into host cells. Hosts exposed to ALVs might be under selective pressure to develop resistance to ALV infection. Indeed, resistance alleles have previously been identified in all four receptor loci in chickens. The tvb gene encodes a receptor, which determines the susceptibility of host cells to ALV subgroup B (ALV-B), ALV-D, and ALV-E. Here we describe the identification of two novel alleles of the tvb receptor gene, which possess independent insertions each within exon 4. The insertions resulted in frameshift mutations that reveal a premature stop codon that causes nonsense-mediated decay of the mutant mRNA and the production of truncated Tvb protein. As a result, we observed that the frameshift mutations in the tvb gene significantly lower the binding affinity of the truncated Tvb receptors for the ALV-B, ALV-D, and ALV-E envelope glycoproteins and significantly reduce susceptibility to infection by ALV-B, ALV-D and ALV-E in vitro and in vivo . Taken together, these findings suggest that frameshift mutation can be a molecular mechanism of reducing susceptibility to ALV and enhance our understanding of virus-host coevolution. IMPORTANCE Avian leukosis virus (ALV) once caused devastating economic loss to the U.S. poultry industry prior the current eradication schemes in place, and it continues to cause severe calamity to the poultry industry in China and Southeast Asia, where deployment of a complete eradication scheme remains a challenge. The tvb gene encodes the cellular receptor necessary for subgroup B, D, and E ALV infection. Two tvb allelic variants that resulted from frameshift mutations have been identified in this study, which have been shown to have significantly reduced functionality in mediating subgroup B, D, and E ALV infection. Unlike the control of herpesvirus-induced diseases by vaccination, the control of avian leukosis in chickens has relied totally on virus eradication measures and host genetic resistance. This finding enriches the allelic pool of the tvb gene and expands the potential for genetic improvement of ALV resistance in varied chicken populations by selection.
    Print ISSN: 0022-538X
    Electronic ISSN: 1098-5514
    Topics: Medicine
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