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排序方式: 共有448条查询结果,搜索用时 15 毫秒
31.
Sung YJ Cheng CL Chen CS Huang HB Huang FL Wu PC Shiao MS Tsay HJ 《Journal of biomedical science》2003,10(4):379-388
Whether reactive oxygen species (ROS) mediate beta-amyloid (A beta) neurotoxicity remains controversial. Naive PC12 cells (PC12) and nerve growth factor-differentiated PC12 cells (dPC12) were used to study the role of ROS in cell death induced by A beta(25-35). The viability of PC12 and dPC12 cells decreased by 30-40% after a 48-hour exposure to 20 microM A beta(25-35). Microscopic examination showed that A beta(25-35) induced necrosis in PC12 cells and apoptosis in dPC12 cells. Vitamin E (100 microM) and other antioxidants protected PC12 cells, but not dPC12 cells, against the cytotoxic effect of A beta(25-35). Since H(2)O(2) has been proposed to be involved in A beta toxicity, the effects of H(2)O(2) on PC12 and dPC12 cells were studied. Differentiated PC12 cells appeared to be significantly more resistant to H(2)O(2) than naive PC12 cells. These data suggest that ROS may mediate A beta(25-35) toxicity in PC12 cells but not in dPC12 cells. Because the intracellular levels of ROS were elevated during the differentiation of PC12 cells, the baseline levels of ROS in these two model cell types may determine the intracellular mediators for A beta(25-35) toxicity. Therefore, the protective effects of antioxidants against A beta may depend upon the redox state of the cells. 相似文献
32.
The aim of this study was to develop a taste-masked oral disintegrating film (ODF) containing donepezil, with fast disintegration
time and suitable mechanical strength, for the treatment of Alzheimer’s disease. Hydroxypropyl methylcellulose, corn starch,
polyethylene glycol, lactose monohydrate and crosspovidone served as the hydrophilic polymeric bases of the ODF. The uniformity,
in vitro disintegration time, drug release and the folding endurance of the ODF were examined. The in vitro results showed that 80% of donepezil hydrochloride was released within 5 minutes with mean disintegration time of 44 seconds.
The result of the film flexibility test showed that the number of folding time to crack the film was 40 times, an indication
of sufficient mechanical property for patient use. A single-dose, fasting, four-period, eight-treatment, double-blind study
involving 16 healthy adult volunteers was performed to evaluate the in situ disintegration time and palatability of ODF. Five parameters, namely taste, aftertaste, mouthfeel, ease of handling and acceptance
were evaluated. The mean in situ disintegration time of ODF was 49 seconds. ODF containing 7 mg of sucralose were more superior than saccharin and aspartame
in terms of taste, aftertaste, mouthfeel and acceptance. Furthermore, the ODF was stable for at least 6 months when stored
at 40°C and 75% relative humidity. 相似文献
33.
Anautogenous mosquitoes require blood meals to promote egg development. If adequate nutrients are not obtained during larval development, the resulting "small" sized adult mosquitoes require multiple blood meals for egg development; markedly increasing host-vector contacts and the likelihood of disease transmission. Nutrient-sensitive target of rapamycin (TOR) signaling is a key signaling pathway that links elevated hemolymph amino acid levels derived from the blood meal to the expression of yolk protein precursors in the fat body. Here we report that the blood-meal-induced activation of the TOR-signaling pathway and subsequent egg maturation depends on the accumulation of adequate nutritional reserves during larval development. We have established well-nourished, "standard" mosquitoes and malnourished, "small" mosquitoes as models to address this nutrient sensitive pathway. This regulatory mechanism involves juvenile hormone (JH), which acts as a mediator of fat body competence, permitting the response to amino acids derived from the blood meal. We demonstrate that treatment with JH results in recovery of the TOR molecular machinery, Aedes aegypti cationic amino acid transporter 2 (AaiCAT2), TOR, and S6 kinase (S6K), in fat bodies of small mosquitoes, enabling them to complete their first gonotrophic cycle after a single blood meal. These findings establish a direct link between nutrient reserves and the establishment of TOR signaling in mosquitoes. 相似文献
34.
W. F. Humphreys Jen-Chieh Shiao Yoshiyuki Iizuka Wann-Nian Tzeng 《Environmental Biology of Fishes》2006,75(4):439-453
Synopsis The blind cavefish, Milyeringa veritas, inhabits an anchialine system, effectively a groundwater estuary, in which salinity varies between fresh and seawater at
different locations and depths. Owing to the inaccessible habitat and the threatened status of the cavefish it is hard to
obtain the biological information needed for their management. This paper explores the utility of otolith Sr:Ca ratio in elucidating
cavefish biology. The mean Sr:Ca ratio of the water inhabited by the cavefish is correlated with both the TDS (total dissolved
solids) of the habitat and with the Sr:Ca ratio of the sagittal otolith of the cavefish inhabiting that site. Mean values
of Sr:Ca in otoliths suggest some cavefish inhabit sea or brackish waters while others remain in freshwater. Some individuals
appear to move between waters of very different TDS at various stages but there is no consistency in the direction or apparent
TDS range of the water bodies inhabited which indicates that the cavefish utilise the different water bodies opportunistically.
Residual analyses indicate clear and routine changes in the TDS of the water occupied at various phases of growth, irrespective
of the TDS at which the cavefish were sampled. Annular markings are present in some otoliths but they cannot be related to
likely periodicities in the subterranean environment. 相似文献
35.
Development of a Swine-Specific Fecal Pollution Marker Based on Host Differences in Methanogen mcrA Genes 下载免费PDF全文
Jennifer A. Ufnar David F. Ufnar Shiao Y. Wang R. D. Ellender 《Applied microbiology》2007,73(16):5209-5217
The goal of this study was to evaluate methanogen diversity in animal hosts to develop a swine-specific archaeal molecular marker for fecal source tracking in surface waters. Phylogenetic analysis of swine mcrA sequences compared to mcrA sequences from the feces of five animals (cow, deer, sheep, horse, and chicken) and sewage showed four distinct swine clusters, with three swine-specific clades. From this analysis, six sequences were chosen for molecular marker development and initial testing. Only one mcrA sequence (P23-2) showed specificity for swine and therefore was used for environmental testing. PCR primers for the P23-2 clone mcrA sequence were developed and evaluated for swine specificity. The P23-2 primers amplified products in P23-2 plasmid DNA (100%), pig feces (84%), and swine waste lagoon surface water samples (100%) but did not amplify a product in 47 bacterial and archaeal stock cultures and 477 environmental bacterial isolates and sewage and water samples from a bovine waste lagoon and a polluted creek. Amplification was observed in only one sheep sample out of 260 human and nonswine animal fecal samples. Sequencing of PCR products from pig feces demonstrated 100% similarity to pig mcrA sequence from clone P23-2. The minimal amount of DNA required for the detection was 1 pg for P23-2 plasmid, 1 ng for pig feces, 50 ng for swine waste lagoon surface water, 1 ng for sow waste influent, and 10 ng for lagoon sludge samples. Lower detection limits of 10−6 g of wet pig feces in 500 ml of phosphate-buffered saline and 10−4 g of lagoon waste in estuarine water were established for the P23-2 marker. This study was the first to utilize methanogens for the development of a swine-specific fecal contamination marker. 相似文献
36.
37.
Jen-Jie Chieh Kai-Wen Huang Yang-De Lee Herng-Er Horng Hong-Chang Yang Chin-Yih Hong 《PloS one》2012,7(10)
With antibody-mediated magnetic nanoparticles (MNPs) applied in cancer examinations, patients must pay at least twice for MNP reagents in immunomagnetic reduction (IMR) of in vitro screening and magnetic resonance imaging (MRI) of in vivo tests. This is because the high maintenance costs and complex analysis of MRI have limited the possibility of in vivo screening. Therefore, this study proposes novel methods for in vivo screening of tumors by examining the AC susceptibility of bound MNPs using scanning superconducting-quantum-interference-device (SQUID) biosusceptometry (SSB), thereby demonstrating high portability and improved economy. The favorable agreement between in vivo tests using SSB and MRI demonstrated the feasibility of in vivo screening using SSB for hepatocellular carcinoma (HCC) targeted by anti-alpha fetoprotein (AFP)-mediated MNPs. The magnetic labeling was also proved by in vitro tests using SSB and biopsy assays. Therefore, patients receiving bioprobe-mediated MNPs only once can undergo in vivo screening using SSB in the future. 相似文献
38.
Nader Morshed William T Ralvenius Alexi Nott L Ashley Watson Felicia H Rodriguez Leyla A Akay Brian A Joughin PingChieh Pao Jay Penney Lauren LaRocque Diego Mastroeni LiHuei Tsai Forest M White 《Molecular systems biology》2020,16(12)
Alzheimer’s disease (AD) is characterized by the appearance of amyloid‐β plaques, neurofibrillary tangles, and inflammation in brain regions involved in memory. Using mass spectrometry, we have quantified the phosphoproteome of the CK‐p25, 5XFAD, and Tau P301S mouse models of neurodegeneration. We identified a shared response involving Siglec‐F which was upregulated on a subset of reactive microglia. The human paralog Siglec‐8 was also upregulated on microglia in AD. Siglec‐F and Siglec‐8 were upregulated following microglial activation with interferon gamma (IFNγ) in BV‐2 cell line and human stem cell‐derived microglia models. Siglec‐F overexpression activates an endocytic and pyroptotic inflammatory response in BV‐2 cells, dependent on its sialic acid substrates and immunoreceptor tyrosine‐based inhibition motif (ITIM) phosphorylation sites. Related human Siglecs induced a similar response in BV‐2 cells. Collectively, our results point to an important role for mouse Siglec‐F and human Siglec‐8 in regulating microglial activation during neurodegeneration. 相似文献
39.
Charge Accumulation and Hysteresis in Perovskite‐Based Solar Cells: An Electro‐Optical Analysis 下载免费PDF全文
Bo Wu Kunwu Fu Natalia Yantara Guichuan Xing Shuangyong Sun Tze Chien Sum Nripan Mathews 《Liver Transplantation》2015,5(19)
Organic–inorganic hybrid perovskite solar cells based on CH3NH3PbI3 have achieved great success with efficiencies exceeding 20%. However, there are increasing concerns over some reported efficiencies as the cells are susceptible to current–voltage (I–V) hysteresis effects. It is therefore essential that the origins and mechanisms of the I–V hysteresis can clearly be understood to minimize or eradicate these hysteresis effects completely for reliable quantification. Here, a detailed electro‐optical study is presented that indicates the hysteresis originates from lingering processes persisting from sub‐second to tens of seconds. Photocurrent transients, photoluminescence, electroluminescence, quasi‐steady state photoinduced absorption processes, and X‐ray diffraction in the perovskite solar cell configuration have been monitored. The slow processes originate from the structural response of the CH3NH3PbI3 upon E‐field application and/or charge accumulation, possibly involving methylammonium ions rotation/displacement and lattice distortion. The charge accumulation can arise from inefficient charge transfer at the perovskite interfaces, where it plays a pivotal role in the hysteresis. These findings underpin the significance of efficient charge transfer in reducing the hysteresis effects. Further improvements of CH3NH3PbI3‐based perovskite solar cells are possible through careful surface engineering of existing TiO2 or through a judicious choice of alternative interfacial layers. 相似文献
40.
Discoidin domain receptor 2 interacts with Src and Shc following its activation by type I collagen 总被引:5,自引:0,他引:5
Ikeda K Wang LH Torres R Zhao H Olaso E Eng FJ Labrador P Klein R Lovett D Yancopoulos GD Friedman SL Lin HC 《The Journal of biological chemistry》2002,277(21):19206-19212
Discoidin domain receptor 2 (DDR2) is an unusual receptor tyrosine kinase in that its ligand is fibrillar collagen rather than a growth factor-like peptide. We examined signal transduction pathways of DDR2. Here we show that DDR2 is also unusual in that it requires Src activity to be maximally tyrosine-phosphorylated, and that Src activity also promotes association of DDR2 with Shc. The interaction with Shc involves a portion of Shc not previously implicated in interaction with receptor tyrosine kinases. These results identify Src kinase and the adaptor protein Shc as key signaling intermediates in DDR2 signal transduction. Furthermore, Src is required for DDR2-mediated transactivation of the matrix metalloproteinase-2 promoter. The data support a model in which Src and the DDR2 receptor cooperate in a regulated fashion to direct the phosphorylation of both the receptor and its targets. 相似文献