2,381 research outputs found

    Universal Thermoelectric Effect of Dirac Fermions in Graphene

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    We numerically study the thermoelectric transports of Dirac fermions in graphene in the presence of a strong magnetic field and disorder. We find that the thermoelectric transport coefficients demonstrate universal behavior depending on the ratio between the temperature and the width of the disorder-broadened Landau levels(LLs). The transverse thermoelectric conductivity αxy\alpha_{xy} reaches a universal quantum value at the center of each LL in the high temperature regime, and it has a linear temperature dependence at low temperatures. The calculated Nernst signal has a peak at the central LL with heights of the order of kB/ek_B/e, and changes sign near other LLs, while the thermopower has an opposite behavior, in good agreement with experimental data. The validity of the generalized Mott relation between the thermoelectric and electrical transport coefficients is verified in a wide range of temperatures.Comment: 4 pages, 4 figures, published versio

    Global transcription profiling reveals differential responses to chronic nitrogen stress and putative nitrogen regulatory components in Arabidopsis

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    <p>Abstract</p> <p>Background</p> <p>A large quantity of nitrogen (N) fertilizer is used for crop production to achieve high yields at a significant economic and environmental cost. Efforts have been directed to understanding the molecular basis of plant responses to N and identifying N-responsive genes in order to manipulate their expression, thus enabling plants to use N more efficiently. No studies have yet delineated these responses at the transcriptional level when plants are grown under chronic N stress and the understanding of regulatory elements involved in N response is very limited.</p> <p>Results</p> <p>To further our understanding of the response of plants to varying N levels, a growth system was developed where N was the growth-limiting factor. An Arabidopsis whole genome microarray was used to evaluate global gene expression under different N conditions. Differentially expressed genes under mild or severe chronic N stress were identified. Mild N stress triggered only a small set of genes significantly different at the transcriptional level, which are largely involved in various stress responses. Plant responses were much more pronounced under severe N stress, involving a large number of genes in many different biological processes. Differentially expressed genes were also identified in response to short- and long-term N availability increases. Putative N regulatory elements were determined along with several previously known motifs involved in the responses to N and carbon availability as well as plant stress.</p> <p>Conclusion</p> <p>Differentially expressed genes identified provide additional insights into the coordination of the complex N responses of plants and the components of the N response mechanism. Putative N regulatory elements were identified to reveal possible new components of the regulatory network for plant N responses. A better understanding of the complex regulatory network for plant N responses will help lead to strategies to improve N use efficiency.</p

    外用喜疗妥致严重皮肤反应1例

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    Objective: To explore the clinical characteristics, diagnosis and prognosis of local severe cutaneous reactions as result of the treatment with Hirudoid. Methods: One case of severe cutaneous reactions as result of the treatment with Hirudoid was reported and the relevant literatures were reviewed. Results: The site of puncture of left arm occurred non-leakage phlebitis with local pain after chemotherapy. The patient was applied the Hirudoid to the affected areas 2 times daily. After 2 days, local skin felt a kind of burning pain and it seems to be getting worse. The skin lesions began as pruritic red macules or papules. It became swelled and bleeding after scratching. We considered that the cutaneous reactions were an allergic response to Hirudoid. We discontinued the Hirudoid and desensitization treatment was used on cure, but it failed to respond to the medical treatment. A hot compress with 50% magnesium sulphate solution can reduce swelling and alleviate pain. Scales of skin peel off and weaved the new skin after 10 days. Conclusion: The case of local severe cutaneous reactions as result of the treatment with Hirudoid is very rare. A hot compress with 50%  magnesium sulphate solution can help to relieve the discomfort. 目的  探讨外用喜疗妥致严重皮肤反应的临床特征及治疗和预后。方法  报道1例外用喜疗妥致严重皮肤反应患者的临床资料并结合相关文献进行分析。结果  患者,女,60岁,化疗后穿刺部位左侧手臂出现非渗漏性静脉炎,局部疼痛。给予喜疗妥每日2次外涂。2天后,患者突感涂抹局部烧灼样疼痛,并可见大片红色斑丘疹奇痒难忍,抓挠后充血肿胀。考虑喜疗妥过敏所致,立即停用喜疗妥,并应用脱敏治疗,效果不佳,局部颜色由红色渐变为暗紫色且肿痛剧烈,给予50%硫酸镁溶液湿热敷。3天后患者症状逐渐减轻,肿胀消退,10天后患处皮肤全部脱落并被新的完好皮肤覆盖。结论  外用喜疗妥致严重皮肤反应非常罕见,50%硫酸镁溶液热敷患处皮肤,可以缓解肿痛,消除症状

    Effects of nebulized ketamine on allergen-induced airway hyperresponsiveness and inflammation in actively sensitized Brown-Norway rats

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    Since airway hyperresponsiveness (AHR) and allergic inflammatory changes are regarded as the primary manifestations of asthma, the main goals of asthma treatment are to decrease inflammation and maximize bronchodilation. These goals can be achieved with aerosol therapy. Intravenous administration of the anesthetic, ketamine, has been shown to trigger bronchial smooth muscle relaxation. Furthermore, increasing evidence suggests that the anti-inflammatory properties of ketamine may protect against lung injury. However, ketamine inhalation might yield the same or better results at higher airway and lower ketamine plasma concentrations for the treatment of asthma. Here, we studied the effect of ketamine inhalation on bronchial hyperresponsiveness and airway inflammation in a Brown-Norway rat model of ovalbumin(OVA)-induced allergic asthma. Animals were actively sensitized by subcutaneous injection of OVA and challenged by repeated intermittent (thrice weekly) exposure to aerosolized OVA for two weeks. Before challenge, the sensitizened rats received inhalation of aerosol of phosphate-buffered saline (PBS) or aerosol of ketamine or injection of ketamine respectivity. Airway reactivity to acetylcholine (Ach) was measured in vivo, and various inflammatory markers, including Th2 cytokines in bronchoalveolar lavage fluid (BALF), as well as induciable nitric oxide synthase (iNOS) and nitric oxide (NO) in lungs were examined. Our results revealed that delivery of aerosolized ketamine using an ultrasonic nebulizer markedly suppressed allergen-mediated airway hyperreactivity, airway inflammation and airway inflammatory cell infiltration into the BALF, and significantly decreased the levels of interleukin-4 (IL-4) in the BALF and expression of iNOS and the concentration of NO in the inflamed airways from OVA-treated rats. These findings collectively indicate that nebulized ketamine attenuated many of the central components of inflammatory changes and AHR in OVA-provoked experimental asthma, potentially providing a new therapeutic approach against asthma

    Electroacupuncture Ameliorates Acute Lung Injury through Promoting Gastrointestinal Motility in Rats with Acute Pancreatitis

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    Objective. Gastrointestinal disfunction and acute lung injury (ALI) were common in acute pancreatitis (AP). The effect of electro-acupuncture (EA) on gastrointestinal motility and ALI in rats with AP was investigated to verify the theory of “lung and large intestine are interior exteriorly related” in traditional Chinese medicine. Methods. Male Sprague-Dawley rats were randomly divided into the normal group, model group, and EA group. AP model was established by three injections of 20% L-arginine at 1 h intervals. EA were applied to bilateral ST-25 and ST-36 for 30 minutes twice a day after modeling for 3 days. Arterial blood, pancreas, lung, and intestinal tissues were collected for detecting the inflammatory factors and histopathology. Intestinal propulsion rate (IPR) was also measured at 72 h. Results. EA treatment improved IPR and increased CCK-8 level compared with model group (P < 0.05). It lowered the serum levels of TNF-α and IL-6 and increased the level of IL-4 with no effect on IL-10. EA treatment reduced serum vasoactive intestinal peptide (VIP) and myeloperoxidase (MPO) level in the lung and the pathologic scores of pancreas, lung and intestine were decreased (P < 0.05). Conclusion. EA treatment could promote gastrointestinal motility through inhibiting VIP, and promoting CCK expression and regulate pro- and anti-inflammatory mediators to ameliorate ALI in AP

    Genome-wide gene responses in a transgenic rice line carrying the maize resistance gene Rxo1 to the rice bacterial streak pathogen, Xanthomonas oryzae pv. oryzicola

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    Abstract Background Non-host resistance in rice to its bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), mediated by a maize NBS-LRR type R gene, Rxo1 shows a typical hypersensitive reaction (HR) phenotype, but the molecular mechanism(s) underlying this type of non-host resistance remain largely unknown. Results A microarray experiment was performed to reveal the molecular mechanisms underlying HR of rice to Xoc mediated by Rxo1 using a pair of transgenic and non-transgenic rice lines. Our results indicated that Rxo1 appeared to function in the very early step of the interaction between rice and Xoc, and could specifically activate large numbers of genes involved in signaling pathways leading to HR and some basal defensive pathways such as SA and ET pathways. In the former case, Rxo1 appeared to differ from the typical host R genes in that it could lead to HR without activating NDR1. In the latter cases, Rxo1 was able to induce a unique group of WRKY TF genes and a large set of genes encoding PPR and RRM proteins that share the same G-box in their promoter regions with possible functions in post-transcriptional regulation. Conclusions In conclusion, Rxo1, like most host R genes, was able to trigger HR against Xoc in the heterologous rice plants by activating multiple defensive pathways related to HR, providing useful information on the evolution of plant resistance genes. Maize non-host resistance gene Rxo1 could trigger the pathogen-specific HR in heterologous rice, and ultimately leading to a localized programmed cell death which exhibits the characteristics consistent with those mediated by host resistance genes, but a number of genes encoding pentatricopeptide repeat and RNA recognition motif protein were found specifically up-regulated in the Rxo1 mediated disease resistance. These results add to our understanding the evolution of plant resistance genes.</p

    Essential oil from Chenopodium ambrosioides L. induces mitochondrial-mediated pathway and endoplasmic reticulum stress-related apoptosis in human liver cancer SMMC-7721 cells

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    Purpose: To evaluate the cytotoxic effect of essential oil derived from Chenopodium ambrosioides L. in Sichuan Province on human liver cancer SMMC-7721 cells, as well as its possible molecular mechanisms.Methods: Cytotoxicity was characterized by MTT assay and transmission electron microscopy (TEM) of SMMC-7721 cells ultrastructure. The apoptotic effect of the essential oil was evaluated by changes in mitochondrial membrane potential and Western blot assay.Results: MTT assay data indicate that the essential oil was cytotoxic to SMMC-7721 cells, while TEN revealed that there were vacuoles and nucleus fragmentation in the SMMC-7721 cell cytosol, cell swelling, and a large amount of leakage. Mitochondrial membrane potential assay and Western Blot data indicate that the essential oil induced cell apoptosis.Conclusion: The essential oil of Chenopodium ambrosioides L. in Sichuan Province seems to induce apoptosis of human liver cancer SMMC-7721 cells via the mitochondrial-mediated pathway and endoplasmic reticulum stress. Thus, this plant requires further investigation as a potential source of ananti-liver cancer drug. Keywords: Chenopodium ambrosioides Essential oil; Anti-tumor activity, Liver cancer Apoptosis, SMMC-7721 cell
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