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991.
Kumar A. Shah Matthew S. Halquist H. Thomas Karnes 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2009,877(14-15):1575-1582
The work described in this paper represents an improvement over a previously published method for the determination of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in human urine by solid phase extraction on a molecularly imprinted polymer column coupled with HPLC and -MS/MS detection. The influence of ion suppression due to sample matrix effect was evaluated, and found to influence the response of NNAL. By changing the liquid chromatography conditions, the response for this method was enhanced approximately 25-fold through avoidance of ionization suppression that was found with a previously published method and sample throughput has been improved. The dynamic range of the assay extends from 20 to 2500 pg/mL with a mean r2 > 0.998. The lower limit of quantitation for the assay was 20 pg/mL despite the use of an inherently lower sensitivity instrument. The method was validated according to current FDA guidelines for bioanalytical method validations. 相似文献
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Christopher B. Newgard Jie An James R. Bain Michael J. Muehlbauer Robert D. Stevens Lillian F. Lien Andrea M. Haqq Svati H. Shah Michelle Arlotto Cris A. Slentz James Rochon Dianne Gallup Olga Ilkayeva Brett R. Wenner William S. Yancy Howard Eisenson Gerald Musante Richard S. Surwit David S. Millington Mark D. Butler Laura P. Svetkey 《Cell metabolism》2009,9(4):311-326
995.
Xiaofei Yan ;Shah Walayat ;Qinfeng Shi ;Jin Zheng ;Yili Wang 《Acta biochimica et biophysica Sinica》2009,(11):900-909
Though accumulated evidence has demonstrated the transformation capacity of human papillomavirus (HPV) type 18 protein E7, the underlying mechanism is still arguable. Developing a protein transduction domain (PTD)-linked E7 molecule is a suitable strategy for assessing the biological functions of the protein. In the present study, HPV18 E7 protein fused to an N-terminal PTD was expressed in the form of glutathione S-transferase fusion protein in Escherichia coli with pGEX-4T- 3 vector. After glutathione-Sepharose 4B bead affinity purification, immunoblot identification and thrombin cleavage, the PTD-18E7 protein showed structural and functional activity in that it potently transduced the ceils and localized into their nuclei. The PTD-18E7 protein transduced the NIH3T3 ceils in 30 min and remained stable for at least 24 h. In addition, the PTD-18E7 protein interacted with retinoblastoma protein (pRB) and caused pRB degradation in the transduced NIH3T3 cells. In contrast to the pRB level, p27 protein level was elevated in the transduced NIH3T3 cells. The PTD-18E7 protein gives us a new tool to study the biological functions of the HPV E7 protein. 相似文献
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997.
Bo Yang Muhammad H. Rahman Yue Liang Saleh Shah Nat N. V. Kav 《Plant Molecular Biology Reporter》2010,28(2):253-263
Canola (Brassica napus L.) is an agriculturally and economically important crop in Canada, and its growth and yield are frequently influenced by
fungal pathogens. Sclerotinia sclerotiorum is among those fungal pathogens and causes stem rot disease in B. napus whereas it has been reported that Brassica carinata is moderately tolerant to S. sclerotiorum. Jasmonic acid/ethylene (JA/ET) and salicylic acid (SA) are phytohormones that are known to be involved in plant disease
responses. To investigate the defense signaling cascades involved in the interaction of B. napus and B. carinata with S. sclerotiorum, we examined the expression of five orthologs of B. napus genes involved in JA/ET or SA signaling pathways using quantitative RT-PCR. Our results indicated that there are differences
in the timing of JA/ET and SA signaling pathways between B. napus and B. carinata. Our results in these two Brassica species also support previous observations that necrotrophic pathogens trigger JA/ET signaling in response to infection.
Finally, we observed that transgenic canola expressing 1-aminocyclopropane-1-carboxylate-deaminase producing low levels of
ET was relatively more susceptible to S. sclerotiorum than its wild-type counterpart, suggesting that ET inhibits S. sclerotiorum-induced symptom development. 相似文献
998.
Fabiola Parussini Isabelle Coppens Parag P. Shah Scott L. Diamond Vern B. Carruthers 《Molecular microbiology》2010,76(6):1340-1357
Regulated exocytosis allows the timely delivery of proteins and other macromolecules precisely when they are needed to fulfil their functions. The intracellular parasite Toxoplasma gondii has one of the most extensive regulated exocytic systems among all unicellular organisms, yet the basis of protein trafficking and proteolytic modification in this system is poorly understood. We demonstrate that a parasite cathepsin protease, TgCPL, occupies a newly recognized va cuolar c ompartment (VAC) that undergoes dynamic fragmentation during T. gondii replication. We also provide evidence that within the VAC or late endosome this protease mediates the proteolytic maturation of proproteins targeted to micronemes, regulated secretory organelles that deliver adhesive proteins to the parasite surface during cell invasion. Our findings suggest that processing of microneme precursors occurs within intermediate endocytic compartments within the exocytic system, indicating an extensive convergence of the endocytic and exocytic pathways in this human parasite. 相似文献
999.
Mohammad Iqbal Muhammad Dawood Shah Chau Ann Lie Chin Kim San 《Molecular and cellular biochemistry》2010,341(1-2):271-277
This study was aimed to evaluate the effect of Strobilanthes crispus extract for possible protection against lipid peroxidation and DNA damage induced by iron nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H2O2). Fe-NTA is a potent nephrotoxic agent and induces acute and subacute renal proximal tubular necrosis by catalyzing the decomposition of H2O2-derived production of hydroxyl radicals, which are known to cause lipid peroxidation and DNA damage. Incubation of postmitochondrial supernatant and/or calf thymus DNA with H2O2 (40 mM) in the presence of Fe-NTA (0.1 mM) induces lipid peroxidation and DNA damage to about 2.3-fold and 2.9-fold, respectively, as compared to control (P < 0.05). In lipid peroxidation protection studies, S. crispus treatment showed a dose-dependent inhibition (45–53% inhibition, P < 0.05) of Fe-NTA and H2O2 induced lipid peroxidation. Similarly, in DNA damage protection studies, S. crispus treatment also showed a dose-dependent inhibition (18–30% inhibition, P < 0.05) of DNA damage. In addition, the protection was closely related to the content of phenolic compounds as evident by S. crispus extract showing the value of 124.48 mg/g total phenolics expressed as gallic acid equivalent (GAE, mg/g of extract). From these studies, it is concluded that S. crispus inhibits peroxidation of membrane lipids and DNA damage induced by Fe-NTA and H2O2 and possesses the potential to be used to treat or prevent degenerative diseases where oxidative stress is implicated. 相似文献
1000.
Sandeep N. Shah Patricia L. Opresko Xiao Meng Marietta Y. W. T. Lee Kristin A. Eckert 《Nucleic acids research》2010,38(4):1149-1162
Common fragile sites (CFS) are chromosomal regions that exhibit instability during DNA replication stress. Although the mechanism of CFS expression has not been fully elucidated, one known feature is a severely delayed S-phase. We used an in vitro primer extension assay to examine the progression of DNA synthesis through various sequences within FRA16D by the replicative human DNA polymerases δ and α, and with human cell-free extracts. We found that specific cis-acting sequence elements perturb DNA elongation, causing inconsistent DNA synthesis rates between regions on the same strand and complementary strands. Pol δ was significantly inhibited in regions containing hairpins and microsatellites, [AT/TA]24 and [A/T]19–28, compared with a control region with minimal secondary structure. Pol δ processivity was enhanced by full length Werner Syndrome protein (WRN) and by WRN fragments containing either the helicase domain or DNA-binding C-terminal domain. In cell-free extracts, stalling was eliminated at smaller hairpins, but persisted in larger hairpins and microsatellites. Our data support a model whereby CFS expression during cellular stress is due to a combination of factors—density of specific DNA secondary-structures within a genomic region and asymmetric rates of strand synthesis. 相似文献