1,973 research outputs found

    The linkages with fires, vegetation composition and human activity in response to climate changes in the Chinese Loess Plateau during the Holocene

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    Holocene paleo-records of the Chinese Loess Plateau loess-soil profiles were used to reconstruct wildfire patterns and landscape evolution. We examine black carbon and charcoal influx, combined with the Magnetic susceptibility, delta C-13 values of soil organic matter, pollen counts and other paleo-environmental proxies to discuss interactions with biomass-climate during the Holocene. The history of fires from the charcoal and black carbon (BC, char and soot) influx at the two sites demonstrates a transition from climate-controlled low amplitude variations with peaks during the Early and Middle Holocene (11-3.1kyearsB.P.) to higher amplitude variability in fire occurrence decoupled from climate and tied to human activities during the Late Holocene (3.1-0kyearsB.P.). The difference in fire patterns was attributed to regional effective moisture and human land use over the entre Loess Plateau; meanwhile, fire activities observed during the Holocene are consistent with variations in vegetation composition inferred from delta C-13 values in soil organic matter, pollen counts, and paleoclimate proxies. Regional wildfires rarely occurred on the desert steppe dominated by a weedy C-3 taxon (Artemisia, Compositae, and Chenopodiaceae dominated)during the late glacial period. A limited biomass would not meet fire propagation in the extreme colder and drier environment of the Loess Plateau during those periods, though. As the climate became ameliorated during the early Holocene, there was an increasing biomass and a sufficient contribution do to high fuel accumulation from C-4 taxon (Gramineae). As the middle Holocene progressed toward warmer and wetter conditions, fire events were less frequent on the steppe and forest-steppe (e.g. expansion of trees C-3,C- Quercus, Corylus) of the Loess Plateau. Subsequently, the number of local and regional fire events have largely increased with the colder and drier climate conditions (e.g. expansion of C-3 weedy), which have been decoupling with intensive anthropogenic burning for farming since the past 3kyr. These data suggests that the regional fire patterns vary strongly along environmental gradients in the effective moisture and regional fuel availability as well as the spatial and temporal distributions of Neolithic burning practices over the Loess Plateau in response to the weakening East Asian monsoon during the Holocene

    Structural Characterization and Antioxidative Activity of Low-Molecular-Weights Beta-1,3-Glucan from the Residue of Extracted Ganoderma lucidum Fruiting Bodies

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    The major cell wall constituent of Ganoderma lucidum (G. lucidum) is β-1,3-glucan. This study examined the polysaccharide from the residues of alkaline-extracted fruiting bodies using high-performance anion-exchange chromatography (HPAEC), and it employed nuclear magnetic resonance (NMR) and mass spectrometry (MS) to confirm the structures. We have successfully isolated low-molecular-weight β-1,3-glucan (LMG), in high yields, from the waste residue of extracted fruiting bodies of G. lucidum. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay evaluated the capability of LMG to suppress H2O2-induced cell death in RAW264.7 cells, identifying that LMG protected cells from H2O2-induced damage. LMG treatment decreased H2O2-induced intracellular reactive oxygen species (ROS) production. LMG also influenced sphingomyelinase (SMase) activity, stimulated by cell death to induce ceramide formation, and then increase cell ROS production. Estimation of the activities of neutral and acid SMases in vitro showed that LMG suppressed the activities of both neutral and acid SMases in a concentration-dependent manner. These results suggest that LMG, a water-soluble β-1,3-glucan recycled from extracted residue of G. lucidum, possesses antioxidant capability against H2O2-induced cell death by attenuating intracellular ROS and inhibiting SMase activity

    Long-term results of intensity-modulated radiotherapy concomitant with chemotherapy for hypopharyngeal carcinoma aimed at laryngeal preservation

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    <p>Abstract</p> <p>Background</p> <p>The objective of this retrospective study is to investigate laryngeal preservation and long-term treatment results in hypopharyngeal carcinoma treated with intensity-modulated radiotherapy (IMRT) combined with chemotherapy.</p> <p>Methods</p> <p>Twenty-seven patients with hypopharyngeal carcinoma (stage II-IV) were enrolled and underwent concurrent chemoradiotherapy. The chemotherapy regimens were monthly cisplatin and 5-fluorouracil for six patients and weekly cisplatin for 19 patients. All patients were treated with IMRT with simultaneous integrated boost technique. Acute and late toxicities were recorded based on CTCAE 3.0 (Common Terminology Criteria for Adverse Events).</p> <p>Results</p> <p>The median follow-up time for survivors was 53.0 months (range 36-82 months). The initial complete response rate was 85.2%, with a laryngeal preservation rate of 63.0%. The 5-year functional laryngeal, local-regional control, disease-free and overall survival rates were 59.7%, 63.3%, 51.0% and 34.8%, respectively. The most common greater than or equal to grade 3 acute and late effects were dysphagia (63.0%, 17 of 27 patients) and laryngeal stricture (18.5%, 5 of 27 patients), respectively. Patients belonging to the high risk group showed significantly higher risk of tracheostomy compared to the low risk group (p = 0.014).</p> <p>Conclusions</p> <p>After long-term follow-up, our results confirmed that patients with hypopharyngeal carcinoma treated with IMRT concurrent with platinum-based chemotherapy attain high functional laryngeal and local-regional control survival rates. However, the late effect of laryngeal stricture remains a problem, particularly for high risk group patients.</p

    3, 4-dihydroxyl-phenyl lactic acid restores NADH dehydrogenase 1 α subunit 10 to ameliorate cardiac reperfusion injury.

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    The present study aimed to detect the role of 3, 4-dihydroxyl-phenyl lactic acid (DLA) during ischemia/reperfusion (I/R) induced myocardial injury with emphasis on the underlying mechanism of DLA antioxidant. Male Spragu-Dawley (SD) rats were subjected to left descending artery occlusion followed by reperfusion. Treatment with DLA ameliorated myocardial structure and function disorder, blunted the impairment of Complex I activity and mitochondrial function after I/R. The results of 2-D fluorescence difference gel electrophoresis revealed that DLA prevented the decrease in NDUFA10 expression, one of the subunits of Complex I. To find the target of DLA, the binding affinity of Sirtuin 1 (SIRT1) to DLA and DLA derivatives with replaced two phenolic hydroxyls was detected using surface plasmon resonance and bilayer interferometry. The results showed that DLA could activate SIRT1 after I/R probably by binding to this protein, depending on phenolic hydroxyl. Moreover, the importance of SIRT1 to DLA effectiveness was confirmed through siRNA transfection in vitro. These results demonstrated that DLA was able to prevent I/R induced decrease in NDUFA10 expression, improve Complex I activity and mitochondrial function, eventually attenuate cardiac structure and function injury after I/R, which was possibly related to its ability of binding to and activating SIRT1

    HuR cytoplasmic expression is associated with increased cyclin A expression and poor outcome with upper urinary tract urothelial carcinoma

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    BACKGROUND: HuR is an RNA-binding protein that post-transcriptionally modulates the expressions of various target genes implicated in carcinogenesis, such as CCNA2 encoding cyclin A. No prior study attempted to evaluate the significance of HuR expression in a large cohort with upper urinary tract urothelial carcinomas (UTUCs). METHODS: In total, 340 cases of primary localized UTUC without previous or concordant bladder carcinoma were selected. All of these patients received ureterectomy or radical nephroureterectomy with curative intents. Pathological slides were reviewed, and clinical findings were collected. Immunostaining for HuR and cyclin A was performed and evaluated by using H-score. The results of cytoplasmic HuR and nuclear cyclin A expressions were correlated with disease-specific survival (DSS), metastasis-free survival (MeFS), urinary bladder recurrence-free survival (UBRFS), and various clinicopathological factors. RESULTS: HuR cytoplasmic expression was significantly related to the pT status, lymph node metastasis, a higher histological grade, the pattern of invasion, vascular and perineurial invasion, and cyclin A expression (p = 0.005). Importantly, HuR cytoplasmic expression was strongly associated with a worse DSS (p < 0.0001), MeFS (p < 0.0001), and UBRFS (p = 0.0370) in the univariate analysis, and the first two results remained independently predictive of adverse outcomes (p = 0.038, relative risk [RR] = 1.996 for DSS; p = 0.027, RR = 1.880 for MeFS). Cyclin A nuclear expression was associated with a poor DSS (p = 0.0035) and MeFS (p = 0.0015) in the univariate analysis but was not prognosticatory in the multivariate analyses. High-risk patients (pT3 or pT4 with/without nodal metastasis) with high HuR cytoplasmic expression had better DSS if adjuvant chemotherapy was performed (p = 0.015). CONCLUSIONS: HuR cytoplasmic expression was correlated with adverse phenotypes and cyclin A overexpression and also independently predictive of worse DSS and MeFS, suggesting its roles in tumorigenesis or carcinogenesis and potentiality as a prognostic marker of UTUC. High HuR cytoplasmic expression might identify patients more likely to be beneficial for adjuvant chemotherapy

    FAST observations of an extremely active episode of FRB 20201124A: IV. Spin Period Search

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    We report the properties of more than 800 bursts detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio telescope (FAST) during an extremely active episode on UTC September 25th-28th, 2021 in a series of four papers. In this fourth paper of the series, we present a systematic search of the spin period and linear acceleration of the source object from both 996 individual pulse peaks and the dedispersed time series. No credible spin period was found from this data set. We rule out the presence of significant periodicity in the range between 1 ms to 100 s with a pulse duty cycle <0.49±0.08< 0.49\pm0.08 (when the profile is defined by a von-Mises function, not a boxcar function) and linear acceleration up to 300300 m s2^{-2} in each of the four one-hour observing sessions, and up to 0.60.6 m s2^{-2} in all 4 days. These searches contest theoretical scenarios involving a 1 ms to 100 s isolated magnetar/pulsar with surface magnetic field <1015<10^{15} G and a small duty cycle (such as in a polar-cap emission mode) or a pulsar with a companion star or black hole up to 100 M_{\rm \odot} and Pb>10P_b>10 hours. We also perform a periodicity search of the fine structures and identify 53 unrelated millisecond-timescale "periods" in multi-components with the highest significance of 3.9 σ\sigma. The "periods" recovered from the fine structures are neither consistent nor harmonically related. Thus they are not likely to come from a spin period. We caution against claiming spin periodicity with significance below \sim 4 σ\sigma with multi-components from one-off FRBs. We discuss the implications of our results and the possible connections between FRB multi-components and pulsar micro-structures.Comment: Accepted by Research in Astronomy and Astrophysics (RAA

    Greglist: a database listing potential G-quadruplex regulated genes

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    The double helix is a conformation that genomic DNA usually assumes; under certain conditions, however, guanine-rich DNA sequences can form a four-stranded structure, G-quadruplex, which is found to play a role in regulating gene expression. Indeed, it has been demonstrated that the G-quadruplex formed in the c-MYC promoter suppresses its transcriptional activity. Recent studies suggest that G-quadruplex motifs (GQMs) are enriched in human gene promoters. To facilitate the research of G-quadruplex, we have constructed Greglist, a database listing potentially G-quadruplex regulated genes. Greglist harbors genes that contain promoter GQMs from genomes of various species, including humans, mice, rats and chickens. Many important genes are found to contain previously unreported promoter GQMs, such as ATM, BAD, AKT1, LEPR, UCP1, APOE, DKK1, WT1, WEE1, WNT1 and CLOCK. Furthermore, we find that not only protein coding genes, 126 human microRNAs also contain promoter GQMs. Greglist therefore provides candidates for further studying G-quadruplex functions and is freely available at http://tubic.tju.edu.cn/greglist
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