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排序方式: 共有290条查询结果,搜索用时 15 毫秒
131.
Gupta N Zahn MM Coppens I Joiner KA Voelker DR 《The Journal of biological chemistry》2005,280(16):16345-16353
Toxoplasma gondii is an intracellular protozoan parasite capable of causing devastating infections in immunocompromised and immunologically immature individuals. In this report, we demonstrate the relative independence of T. gondii from its host cell for aminoglycerophospholipid synthesis. The parasite can acquire the lipid precursors serine, ethanolamine, and choline from its environment and use them for the synthesis of its major lipids, phosphatidylserine (PtdSer), phosphatidylethanolamine (PtdEtn), and phosphatidylcholine (PtdCho), respectively. Dimethylethanolamine (Etn(Me)(2)), a choline analog, dramatically interfered with the PtdCho metabolism of T. gondii and caused a marked inhibition of its growth within human foreskin fibroblasts. In tissue culture medium supplemented with 2 mm Etn(Me)(2), the parasite-induced lysis of the host cells was dramatically attenuated, and the production of parasites was inhibited by more than 99%. The disruption of parasite growth was paralleled by structural abnormalities in its membranes. In contrast, no negative effect on host cell growth and morphology was observed. The data also reveal that the Etn(Me)(2)-supplemented parasite had a time-dependent decrease in its PtdCho content and an equivalent increase in phosphatidyldimethylethanolamine, whereas other major lipids, PtdSer, PtdEtn, and PtdIns, remained largely unchanged. Relative to host cells, the parasites incorporated more than 7 times as much Etn(Me)(2) into their phospholipid. These findings reveal that Etn(Me)(2) selectively alters parasite lipid metabolism and demonstrate how selective inhibition of PtdCho synthesis is a powerful approach to arresting parasite growth. 相似文献
132.
The reduction in maize leaf growth under mild drought affects the transition between cell division and cell expansion and cannot be restored by elevated gibberellic acid levels 下载免费PDF全文
133.
Jaime Curtis-Fisk Paul Sheskey Karen Balwinski Karen Coppens Carol Mohler Jin Zhao 《AAPS PharmSciTech》2012,13(4):1170-1178
This study investigated the effects of polymer dispersion and hydration conditions on hypromellose (HPMC) film properties, such as strength, oxygen permeability, water vapor transmission, clarity, and haze. The focus of the study was to build a better understanding of the impact that changes to HPMC dispersion and hydration conditions have on performance properties of the resulting films. This understanding could potentially lead to more flexible formulation guidelines for formulators. Films of HPMC 2906 (USP) were produced from aqueous solutions prepared using various formulation conditions. Results showed that tensile properties and oxygen permeability were not significantly affected by the variables used. The differences observed in water vapor transmission are unlikely to affect practical application of the material. However, the differences observed in clarity and haze at 50°C hydration temperature could affect the appearance of a capsule or coated tablet. Several methods were used to determine whether loss of optical properties was due to surface phenomena or bulk defects within a film. Results indicated that the cloudy appearance was primarily due to surface roughness. Based on this information, there is some flexibility in formulation conditions; however, hydration temperatures greater than 25°C are not recommended. 相似文献
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135.
We investigated the cytotoxic, neurotoxic, apoptotic and antiproliferative effects of extracts from Petalonia fascia, Jania longifurca and Halimeda tuna on the MCF-7 breast cancer cell line. J. longifurca extracts were more toxic than those of P. fascia and H. tuna. The algal extracts showed significant toxic effects at different dilutions. The toxic effects were due to increased oxidative stress and resulted in apoptosis. Algal toxicity may exert negative effects through the food chain or by direct interaction. Algal toxicity also has potential for cancer therapy. The toxic effects that we observed may be especially important for therapy for breast tumors. 相似文献
136.
Konstantinos Doris Sophia P Karabela Chrysoula A Kairi Davina CM Simoes Charis Roussos Spyros G Zakynthinos Ioannis Kalomenidis Timothy S Blackwell Georgios T Stathopoulos 《Respiratory research》2010,11(1):118
Background
Although the relationship between allergic inflammation and lung carcinogenesis is not clearly defined, several reports suggest an increased incidence of lung cancer in patients with asthma. We aimed at determining the functional impact of allergic inflammation on chemical carcinogenesis in the lungs of mice.Methods
Balb/c mice received single-dose urethane (1 g/kg at day 0) and two-stage ovalbumin during tumor initiation (sensitization: days -14 and 0; challenge: daily at days 6-12), tumor progression (sensitization: days 70 and 84; challenge: daily at days 90-96), or chronically (sensitization: days -14 and 0; challenge: daily at days 6-12 and thrice weekly thereafter). In addition, interleukin (IL)-5 deficient and wild-type C57BL/6 mice received ten weekly urethane injections. All mice were sacrificed after four months. Primary end-points were number, size, and histology of lung tumors. Secondary end-points were inflammatory cells and mediators in the airspace compartment.Results
Ovalbumin provoked acute allergic inflammation and chronic remodeling of murine airways, evident by airspace eosinophilia, IL-5 up-regulation, and airspace enlargement. Urethane resulted in formation of atypical alveolar hyperplasias, adenomas, and adenocarcinomas in mouse lungs. Ovalbumin-induced allergic inflammation during tumor initiation, progression, or continuously did not impact the number, size, or histologic distribution of urethane-induced pulmonary neoplastic lesions. In addition, genetic deficiency in IL-5 had no effect on urethane-induced lung tumorigenesis.Conclusions
Allergic inflammation does not impact chemical-induced carcinogenesis of the airways. These findings suggest that not all types of airway inflammation influence lung carcinogenesis and cast doubt on the idea of a mechanistic link between asthma and lung cancer. 相似文献137.
Angela CM Luyf Barbera DC van Schaik Michel de Vries Frank Baas Antoine HC van Kampen Silvia D Olabarriaga 《BMC bioinformatics》2010,11(1):598
Background
Bioinformatics is confronted with a new data explosion due to the availability of high throughput DNA sequencers. Data storage and analysis becomes a problem on local servers, and therefore it is needed to switch to other IT infrastructures. Grid and workflow technology can help to handle the data more efficiently, as well as facilitate collaborations. However, interfaces to grids are often unfriendly to novice users. 相似文献138.
Joseph P McElroy Wuyan Zhang Kenneth J Koehler Susan J Lamont Jack CM Dekkers 《遗传、选种与进化》2006,38(6):637-655
Survival traits and selective genotyping datasets are typically not normally distributed, thus common models used to identify QTL may not be statistically appropriate for their analysis. The objective of the present study was to compare models for identification of QTL associated with survival traits, in particular when combined with selective genotyping. Data were simulated to model the survival distribution of a population of chickens challenged with Marek disease virus. Cox proportional hazards (CPH), linear regression (LR), and Weibull models were compared for their appropriateness to analyze the data, ability to identify associations of marker alleles with survival, and estimation of effects when all individuals were genotyped (full genotyping) and when selective genotyping was used. Little difference in power was found between the CPH and the LR model for low censoring cases for both full and selective genotyping. The simulated data were not transformed to follow a Weibull distribution and, as a result, the Weibull model generally resulted in less power than the other two models and overestimated effects. Effect estimates from LR and CPH were unbiased when all individuals were genotyped, but overestimated when selective genotyping was used. Thus, LR is preferred for analyzing survival data when the amount of censoring is low because of ease of implementation and interpretation. Including phenotypic data of non-genotyped individuals in selective genotyping analysis increased power, but resulted in LR having an inflated false positive rate, and therefore the CPH model is preferred for this scenario, although transformation of the data may also make the Weibull model appropriate for this case. The results from the research presented herein are directly applicable to interval mapping analyses. 相似文献
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140.
Flavie Tortereau Hélène Gilbert Henri CM Heuven Jean-Pierre Bidanel Martien AM Groenen Juliette Riquet 《遗传、选种与进化》2010,42(1):42