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5-Methylated cytosine is a frequent modification in eukaryotic RNA and DNA influencing mRNA stability and gene expression. Here we show that free 5-methylcytidine (5mC) and 5-methyl-2'-deoxycytidine are generated from nucleic acid turnover in Arabidopsis thaliana, and elucidate how these cytidines are degraded, which is unclear in eukaryotes. First CYTIDINE DEAMINASE produces 5-methyluridine (5mU) and thymidine which are subsequently hydrolyzed by NUCLEOSIDE HYDROLASE 1 (NSH1) to thymine and ribose or deoxyribose. Interestingly, far more thymine is generated from RNA than from DNA turnover, and most 5mU is directly released from RNA without a 5mC intermediate, since 5-methylated uridine (m5U) is an abundant RNA modification (m5U/U â¼1%) in Arabidopsis. We show that m5U is introduced mainly by tRNA-SPECIFIC METHYLTRANSFERASE 2A and 2B. Genetic disruption of 5mU degradation in the NSH1 mutant causes m5U to occur in mRNA and results in reduced seedling growth, which is aggravated by external 5mU supplementation, also leading to more m5U in all RNA species. Given the similarities between pyrimidine catabolism in plants, mammals and other eukaryotes, we hypothesize that the removal of 5mU is an important function of pyrimidine degradation in many organisms, which in plants serves to protect RNA from stochastic m5U modification.
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Arabidopsis , RNA , Animais , Timina , Uridina/metabolismo , Pirimidinas/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , DNA , Mamíferos/genéticaRESUMO
In this paper, we investigated the valley transport properties of silicene on a GaAs(111) substrate. Hydrogen atoms as intercalation substantially weaken the interaction between silicene and GaAs(111) substrate. Thus, the equivalent intervalley scattering between K valleys and the non-equivalent intervalley scattering between Γ and K valleys were studied. The effects of external temperature, the distance Lz between silicene and the substrate, and the buckling height d of silicene on intervalley scattering were also considered. Our results showed that the intervalley scattering rates of silicene on GaAs(111) were about 1011-1012 s-1, which indicate that the weakened interaction between silicene and the substrate can effectively reduce intervalley scattering rates. The equivalent intervalley scattering of silicene was insensitive to changes of the distance Lz between silicene and the substrate and the buckling height d of silicene, but the non-equivalent intervalley scattering was greatly affected by these changes. The research results have laid a theoretical foundation for the study of the transport properties and application of silicene on semiconductor substrates.
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BACKGROUND The primary objective of this study was to assess the cumulative incidence of cause-specific mortality (CSM) and other causes of mortality (OCM) for patients with metastatic pancreatic duct adenocarcinoma (mPDAC). The secondary objective was to calculate the probability of CSM and build a competing risk nomogram to predict CSM for mPDAC. MATERIAL AND METHODS We identified patients with mPDAC between 2010 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. We assessed the cumulative incidence function (CIF) for cause-specific mortality and other causes of mortality. We used Gray's test to investigate the differences. The Fine and Gray proportional subdistribution hazard model was applied to model CIF. And a competing risk nomogram was built to predict the probability of CSM for mPDAC. RESULTS There were 10 527 eligible patients diagnosed with mPDAC from 2010 to 2015 who were included in our formal analysis. The 6-month cumulative incidence of CSM was 60.3% and 5.9% for other causes. Predictors of SCM for mPDAC included surgery, age, tumor size, chemotherapy, radiation therapy, bone metastasis, and liver metastasis. The nomogram was proven to be well calibrated, and had good model discriminative ability. CONCLUSIONS We assessed the CIF of CSM and competing risk mortality in patients with mPDAC using the SEER database. The Fine and Gray proportional subdistribution hazard model performance was good, with a concordance index of 0.74, and the competing-risks nomogram was built, which can be a helpful predictive tool for cases with mPDAC. However, a validation sample data set and further verification are still needed to assess a profile for prognostic use in a prospective study.
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Carcinoma Ductal Pancreático/mortalidade , Nomogramas , Adenocarcinoma/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Causas de Morte , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Estadiamento de Neoplasias/métodos , Neoplasias Pancreáticas/mortalidade , Probabilidade , Prognóstico , Modelos de Riscos Proporcionais , Estudos Prospectivos , Fatores de Risco , Programa de SEER , Neoplasias PancreáticasRESUMO
BACKGROUND: Raphanus sativus L. cv. Yanghua sprouts are rich in health-promoting anthocyanins; thus hypocotyls show a red color under light. In this study, effects of UV-B irradiation at 5 W m(-2) on anthocyanin biosynthesis in the hypocotyls of radish sprouts were investigated. RESULTS: Anthocyanins began to accumulate rapidly from 24 h irradiation and increased continuously until 48 h, showing a similar pattern to phenylalanine ammonia lyase (PAL) activity, with a correlation coefficient of 0.804. The expression of DFR and ANS paralleled the upward trend in anthocyanin accumulation, while CHS, CHI and F3H were upregulated before accumulation. When sprouts were moved into the dark from UV-B, the anthocyanin accumulation did not stop immediately. By contrast, anthocyanin accumulated continuously for more than 12 h in the dark, which was further supported by the significantly higher PAL activity monitored at 24 h after irradiation. Similarly, the transcript levels of anthocyanin biosynthesis-related genes were much higher over 6 h after 12 h UV-B irradiation. CONCLUSION: UV-B-induced anthocyanin accumulation continues in the dark after irradiation, which was supported by unfading PAL activity and high levels of biosynthesis-related genes. This will provide evidence to produce high-quality sprouts with more anthocyanins but less energy wastage in practice.
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Antocianinas/biossíntese , Raphanus , Raios Ultravioleta , Humanos , Hipocótilo/metabolismoRESUMO
OBJECTIVE: The expression of vascular endothelial growth factor-A (VEGF-A) in snakebite patients, its value in patient prognosis and the correlation of VEGF-A with renal function were analysed. METHODS: A total of 124 snakebite patients admitted from January 2019 to January 2021 were retrospectively analysed and included in the observation group, and 40 healthy individuals who underwent physical examination in the same hospital within the same period were included in the control group. The t-test was used in analysing differences between the serum VEGF-A levels of the observation and control groups and changes in VEGF-A and renal function indices before and after treatment in the observation group. The effects of treatment on each patient in the observation group were evaluated, and the patients were divided into improved and unimproved groups according to the post-treatment condition. The predictive value of VEGF-A and renal function indices in patients in the improved and unimproved groups and their efficacy for snakebite patients were analysed through receiver operating characteristic (ROC) analysis. Finally, correlation analysis was used in evaluating the correlation between VEGF-A and renal function indices. RESULTS: VEGF-A was significantly higher in patients in the observation group (339.66 ± 97.72 pg/mL) than in patients in the control group (52.41 ± 8.93 pg/mL; p < 0.001). VEGF-A and renal function indices in the serum of patients were significantly lower after treatment than those before treatment (p < 0.0001). According to efficacy, the patients were divided into improved group (n = 102) and unimproved group (n = 22). The pre-treatment VEGF-A levels were significantly lower in patients in the improved group (318.47 ± 90.80 pg/mL) than in patients in the unimproved group (437.88 ± 63.16 pg/mL; p < 0.001). ROC curve analysis revealed that the area under the curve for VEGF-A in predicting patient treatment efficacy was 0.886, and VEGF-A was positively correlated with blood urea nitrogen, creatinine and cystin C but negatively correlated with glomerular filtration rate (p < 0.001). CONCLUSIONS: VEGF-A was highly expressed in snakebite patients and can be used as an observational indicator for predicting the prognosis of snakebite patients.
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Mordeduras de Serpentes , Humanos , Mordeduras de Serpentes/terapia , Fator A de Crescimento do Endotélio Vascular , Estudos Retrospectivos , Biomarcadores , HospitalizaçãoRESUMO
To determine the clinical efficacy of Zuqing Xu 'Wuduling' powder for snake injury on the swelling of the affected limb bitten by Agkistrodon halys. Sixty-five patients with Agkistrodon halys bite were assigned to a treatment group (n = 35) or control group (n = 30). The treatment group was additionally given 'Wuduling' powder dressing locally based on the therapy to the control group with conventional Western medicine. Clinical efficacy and improvement of traditional Chinese medicine symptoms and signs in the two groups were evaluated. The treatment group showed a notably higher cure rate than the control group. After 3 days of therapy, the swelling and pain of the affected limb in the treatment group were greatly alleviated. Additionally, after 7 days of therapy, the swelling and pain of the affected limb in the treatment group were more greatly alleviated, and those in the control group were also alleviated. The comparison of the two groups during the same period showed more obvious alleviation of swelling and pain in the treatment group than that in the other. Moreover, the treatment group experienced notably shorter disappearing time of swelling and pain than the control group. After treatment, the levels of CRP, TBIL, Cr, ALT, AST, BUN, CK, LDH and CK-MB in both groups declined notably, with notably lower levels of them in the treatment group than those in the other. Zuqing Xu 'Wuduling' powder for snake injury can substantially alleviate the swelling and local pain of affected limbs bitten by Agkistrodon halys.
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In this paper, we investigated the electronic and optical properties of silicene on GaAs(111) substrates (silicene/HGaAs) on the basis of first-principles density functional theory. The hydrogen intercalation introduced substantially weakened the interaction between silicene and the GaAs(111) substrate and induced considerable bandgaps in silicene/HGaAs heterostructures. The effects of the interlayer spacing (L) between silicene and the substrate, silicene buckling height (h), biaxial strain (ε), and external electric field (F) on the electronic properties were also considered. Our results showed that the electronic properties of silicene/HGaAs heterostructures could be controlled by adjusting L and h and applying ε and an external F. Silicene/HGaAs heterostructures possessed the typical optical absorption properties of freestanding silicene and had high absorption coefficients. Besides, some strong peaks of absorption spectra and energy loss spectra existed in the ultraviolet light region, which showed that silicene/HGaAs heterostructures had evident enhancement in the ultraviolet light region. Results laid a theoretical foundation for the study of the electronic and optical properties and applications of silicene on semiconductor substrate devices.
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Sequential extraction integrated with isotope analysis was carried out on a sediment core from Liaodong Bay, northeast China, for characterizing Pb in various extraction phases and its possible sources. Results show that in all extracted fractions Pb concentrations increased abruptly in the top part of the sediments that deposited after 1980, but remained lower and rather constant before 1980. Consistent with the variation pattern of Pb concentration, the 206Pb/207Pb ratio displays a dramatic decrease around 1980. These findings strongly suggest serious Pb pollution since then. The Pb concentration and the isotopic ratios of 206Pb/207Pb and 208Pb/207Pb in the residual fraction show rather small changes through the entire core, and are similar to those of uncontaminated Chinese loess, possibly representing the characteristics of the regional geogenic background. The isotopic ratios of the sediments before 1980 varied in different extracted fractions with a linear pattern, from the residual at the highest toward the average signature of automobile exhausts and Pb-Zn deposits, implying a prominent two-end member mixing style of the Pb origin; one is the regional geologic background and the other is anthropogenic sources. The difference in isotopic ratios between the extractions might be indicative of varied proportions of the two sources. For sediments after 1980, however, the isotope ratios in nonresidual fractions are all relatively low and show little differentiation, which may suggest that polluted Pb dominates all the extracted fractions for the top part of the core.
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Sedimentos Geológicos/análise , Chumbo/análise , Poluentes Químicos da Água/análise , Poluentes Radioativos da Água/análise , Radioisótopos de Césio , China , Radioisótopos de Chumbo , Controle de Qualidade , Soluções , SolventesRESUMO
[This corrects the article DOI: 10.1007/s11671-009-9398-3.].
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In the framework of effective-mass envelope function theory, including the effect of Rashba spin-orbit coupling, the binding energy E(b) and spin-orbit split energy Ð of the ground state of a hydrogenic donor impurity in AlGaN/GaN triangle-shaped potential heterointerface are calculated. We find that with the electric field of the heterojunction increasing, (1) the effective width of quantum well WÌ decreases and (2) the binding energy increases monotonously, and in the mean time, (3) the spin-orbit split energy Ð decreases drastically. (4) The maximum of Ð is 1.22 meV when the electric field of heterointerface is 1 MV/cm.