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31.
32.
<正>Aristolochic acids, mutational signature, and hepatocellular carcinoma Aristolochic acids (AA) are the etiologic agents of aristolochic acid nephropathy (AAN) and contribute to the global prevalence of chronic kidney disease and urothelial cancer (Grollman et al., 2007). DNA adducts formed by AA generate a unique AT transversions mutation spectrum at 相似文献
33.
The vast majority of flowering plants rely solely on insects for pollination. A number of pathogens have evolved mechanisms to exploit these close associations and use pollinators as vectors of infective propagules. Factors that affect pollinator movements and successful pollination may in turn also influence successful transmission of fungal spores. Here we investigate the effect of host density and the frequency of diseased Oxalis lanata individuals infected by the anther-smut fungus, Thecaphora capensis, on the likelihood of receiving pollen and fungal spores. Specifically, we determined the numbers of spores and pollen grains deposited on stigmatic surfaces of selected flowers under natural and standardized conditions where host density and disease frequency varied. The effect of host flower density and diseased flower frequency on pollen and spore transfer was variable under natural conditions and these factors interacted significantly. However, an increase in host density and disease frequency significantly influenced pollen and spore deposits under standardized conditions. The effect of host density was, however, not linear and an optimal flower density for pollen and fungal spore transmission was found. Similar to other systems of vector-borne disease, the transmission of anther-smut of Oxalis lanata is more frequency-dependent than density-dependent. This study represents a first step towards understanding the disease transmission process of T. capensis on Oxalis and lays the foundation for future comparative studies between this and other systems to develop and test general hypotheses of disease dynamics in vector-borne disease transmission systems. 相似文献
34.
Peng Wang Ronghua Luo Min Zhang Yaqing Wang Tianzhang Song Tingting Tao Zhongyu Li Lin Jin Hongyi Zheng Wenwen Chen Mengqian Zhao Yongtang Zheng Jianhua Qin 《Cell death & disease》2020,11(12)
COVID-19, caused by SARS-CoV-2, is an acute and rapidly developing pandemic, which leads to a global health crisis. SARS-CoV-2 primarily attacks human alveoli and causes severe lung infection and damage. To better understand the molecular basis of this disease, we sought to characterize the responses of alveolar epithelium and its adjacent microvascular endothelium to viral infection under a co-culture system. SARS-CoV-2 infection caused massive virus replication and dramatic organelles remodeling in alveolar epithelial cells, alone. While, viral infection affected endothelial cells in an indirect manner, which was mediated by infected alveolar epithelium. Proteomics analysis and TEM examinations showed viral infection caused global proteomic modulations and marked ultrastructural changes in both epithelial cells and endothelial cells under the co-culture system. In particular, viral infection elicited global protein changes and structural reorganizations across many sub-cellular compartments in epithelial cells. Among the affected organelles, mitochondrion seems to be a primary target organelle. Besides, according to EM and proteomic results, we identified Daurisoline, a potent autophagy inhibitor, could inhibit virus replication effectively in host cells. Collectively, our study revealed an unrecognized cross-talk between epithelium and endothelium, which contributed to alveolar–capillary injury during SARS-CoV-2 infection. These new findings will expand our understanding of COVID-19 and may also be helpful for targeted drug development.Subject terms: Mechanisms of disease, Viral infection 相似文献
35.
Semiparametric Regression in Size-Biased Sampling 总被引:1,自引:0,他引:1
Ying Qing Chen 《Biometrics》2010,66(1):149-158
Summary . Size-biased sampling arises when a positive-valued outcome variable is sampled with selection probability proportional to its size. In this article, we propose a semiparametric linear regression model to analyze size-biased outcomes. In our proposed model, the regression parameters of covariates are of major interest, while the distribution of random errors is unspecified. Under the proposed model, we discover that regression parameters are invariant regardless of size-biased sampling. Following this invariance property, we develop a simple estimation procedure for inferences. Our proposed methods are evaluated in simulation studies and applied to two real data analyses. 相似文献
36.
Following arteriolar occlusion, tissue oxygen concentration decreases and anoxic tissue eventually develops. Although anoxia
first appears in the region most distal to the capillary at the venous end, it eventually spreads throughout the entire region
of supply. In this paper the changing oxygen concentration, from the time of occlusion until the tissue is entirely anoxic,
is examined mathematically. The equations governing oxygen transport to tissue are solved by iterating a nonlinear integral
equation. This solution is valid until anoxia first appears. After anoxia develops it is necessary to solve a moving boundary
problem. This is done using the method of matched asymptotic expansions, and accurate solutions are obtained for a wide range
of physiological conditions. 相似文献
37.
C Wang 《Biochimica et biophysica acta》1986,888(1):107-115
Insulin receptors of rat skeletal muscle were purified by first extracting a plasma membrane-enriched pellet obtained from a muscle homogenate with Triton X-100, followed by WGA-Sepharose and insulin-Sepharose affinity chromatography. Routinely, 4-5 micrograms of purified receptor were obtained from 15 g of tissue. The purified receptors are composed of two major polypeptides with molecular weights of 130,000 and 95,000, respectively. The binding of [125I]insulin by the purified receptors was analyzed by a Scatchard plot. There are at least two binding components. The high-affinity component, with an apparent association constant (Ka) of 2.0 X 10(9) M-1, comprises 10% of the total insulin binding sites; while the low-affinity component, with a Ka value of 1.4 X 10(8) M-1, represents 90% of the binding sites. Assuming the insulin receptor to have a molecular weight of 300,000, the receptor binds 1.7 mol of insulin per mol at saturation. Insulin is capable of stimulating the autophosphorylation of the beta-subunit of the muscle insulin receptor (Mr 95,000) by 5-10-fold. The stoichiometry of this phosphorylation reaction was determined as 0.8 phosphate per insulin binding site after a 10 min incubation with 100 nM insulin. In a previous report, I showed that the insulin stimulation of glucose transport in diaphragms from neonatal rats was small, even although the diaphragms had normal levels of insulin receptors and glucose transporters (Wang, C. (1985). Proc. Natl. Acad. Sci. USA 82, 3621-3625). To determine whether or not receptor autophosphorylation might be related to this insensitivity to insulin, the level of receptor phosphorylation was quantitated in diaphragms from rats at different stages of development. Autophosphorylation remains unchanged from birth to 21 days of age, suggesting that the lower insulin-stimulated glucose uptake by diaphragms at early stages of postnatal development as compared to that by diaphragms of older rats, is not due to a difference in receptor kinase. 相似文献
38.
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40.
Dongliang Liu Jun Liu Weilan Wang Lijie Xia Jianhua Yang Surong Sun Fuchun Zhang 《Food biophysics》2016,11(4):319-331
Cecropin XJ, as a heat stable antimicrobial peptide (AMP), displayed broad bacteriostatic activities, effectively inhibited proliferation of cancer cells and induced cell apoptosis in vitro. However, it exhibited little hemolytic activity and very low cytotoxicity to erythrocytes and normal cells. Although exerts multiple remarkable bioactivities, the refined molecular conformation of native Cecropin XJ remains unsolved. The aim of the present study is to comprehensively investigate the physicochemical characteristics and structure-function relationship of this antimicrobial peptide by using a series of bioinformatics and experimental approaches. In this study, we revealed that the mature Cecropin XJ consists of 41 amino acids, containing two α-helical structures from Lys7 to Lys25 and from Ala29 to Ile39. The phylogenetic tree indicated that Cecropin XJ belongs to the Class I AMPs of cecropin family. Hydrophobic analysis showed Cecropin XJ is a typical amphiphilic molecule. The surface of Cecropin XJ was found to have a much wide range of electrostatic potential from ?83.243 to +83.243. The amphipathicity and surface potential of Cecropin XJ partially supported the AMP pore-forming hypothesis. Scanning electron microscopy experimentally confirmed the damages of Cecropin XJ to microbial membrane. Four predicted docking sites respectively for magnesium ion (Mg2+), adenosine diphosphate (ADP), bacteriopheophytin (BPH), and guanosine triphosphate (GTP) were found on the surface of Cecropin XJ. Thereinto, Mg2+ was experimentally proved to suppress the antibacterial activity of Cecropin XJ; both GTP and ADP enhanced the bactericidal activities to varying degrees. The present study provides a foundation for further investigation of molecular evolution, structural modification, and functional mechanisms of Cecropin XJ. 相似文献