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排序方式: 共有190条查询结果,搜索用时 15 毫秒
1.
Branka Brukner Dabović Dragica Radojković Predrag Minić Jovan Savić Ana Savić 《Human genetics》1992,88(6):699-700
Summary A study was undertaken to find the frequency of the F508 deletion and those of the G551D, R553X and G524X mutations among the mainly Slavic population of Serbia, Bosnia, Herzegovina, and Montenegro and compare the frequencies determined with those in other European populations. The F508 mutation was found to account for about 70% of CF genes in central Jugoslavia, where its frequency is significantly higher than elsewhere in Southern European populations. 相似文献
2.
Preimplantation embryo development was arrested at the premorula stage in hamsters ovariectomized on Day 1 of pregnancy. This effect was reversed when 500 micrograms progesterone were administered daily. Oestradiol-17 beta given alone had no significant effect on the cleavage rate or blastocyst formation, but a synergistic response was evident when a suboptimal (30 micrograms) dose of progesterone was given with 50 ng oestradiol-17 beta. Cholesterol and hydrocortisol had no effect on embryo development. 相似文献
3.
Summary In a pot culture experiment on a sierozem sandy soil (pH 8.2) rates of added B at 3 ppm although decreased root yield significantly
but shoot and grain yield was unaffected even at 6 ppm added B, even though shoot B concentration was as high as 360 ppm and
Ca/B ratio as low as 11. At 6 ppm applied B, shoot yield was increased by 18.5 per cent, whereas grain yield was at par with
control. The results suggested that Ca/B ratio in barley straw was not a reliable index for determing the magnitude of B problem
in the soil. 相似文献
4.
M G Maulik S D Seth S C Manchanda U Singh S K Maulik 《Indian journal of experimental biology》1991,29(9):837-840
Biochemical alterations in the hearts of non-diabetic and 5 weeks of streptozotocin-induced diabetic rats following isoproterenol (ISO) administration were compared. Serum lactate dehydrogenase (LDH) and myocardial adenosine triphosphate (ATP), creatine phosphate (CP), lactate and glycogen were used as indices of myocardial injury. Hearts from diabetic rats (blood glucose greater than 350 mg/dl), before ISO administration, had normal lactate levels but significantly low high-energy phosphate (HEP) levels and high glycogen levels in comparison to non-diabetic rats. No difference was observed in serum LDH levels between these two groups. ISO administration to non-diabetic rats caused myocardial necrosis as evidenced by a significant depletion of myocardial glycogen and HEPs along with significant myocardial lactate accumulation and an increase in serum LDH. However, the hearts from diabetic rats failed to show any significant HEP depletion, accumulation of lactate and leakage of LDH into serum following ISO-administration, though myocardial glycogen level was significantly lowered. These observations, in conjunction with earlier reports, point to the hypothesis that, in diabetes, there are certain alterations in the sarcolemma which hamper the process by which ISO causes myocardial necrosis. 相似文献
5.
Exploring polyethylenimine-mediated DNA transfection and the proton sponge hypothesis 总被引:6,自引:0,他引:6
BACKGROUND: The relatively high transfection efficiency of polyethylenimine (PEI) vectors has been hypothesized to be due to their ability to avoid trafficking to degradative lysosomes. According to the proton sponge hypothesis, the buffering capacity of PEI leads to osmotic swelling and rupture of endosomes, resulting in the release of the vector into the cytoplasm. METHODS: The mechanism of PEI-mediated DNA transfer was investigated using quantitative methods to study individual steps in the overall transfection process. In addition to transfection efficiency, the cellular uptake, local pH environment, and stability of vectors were analyzed. N-Quaternized (and therefore non-proton sponge) versions of PEI and specific cell function inhibitors were used to further probe the proton sponge hypothesis. RESULTS: Both N-quaternization and the use of bafilomycin A1 (a vacuolar proton pump inhibitor) reduced the transfection efficiency of PEI by approximately two orders of magnitude. Chloroquine, which buffers lysosomes, enhanced the transfection efficiency of N-quaternized PEIs and polylysine by 2-3-fold. In contrast, chloroquine did not improve the transfection efficiency of PEI. The measured average pH environment of PEI vectors was 6.1, indicating that they successfully avoid trafficking to acidic lysosomes. Significantly lower average pH environments were observed for permethyl-PEI (pH 5.4), perethyl-PEI (pH 5.1), and polylysine (pH 4.6) vectors. Cellular uptake levels of permethyl-PEI and perethyl-PEI vectors were found to be 20 and 90% higher, respectively, than that of parent PEI vectors, indicating that the reduction in transfection activity of the N-quaternized PEIs is due to a barrier downstream of cellular uptake. A polycation/DNA-binding affinity assessment showed that the more charge dense N-quaternized PEIs bind DNA less tightly than PEI, demonstrating that poor vector unpackaging was not responsible for the reduced transfection activity of the N-quaternized PEIs. CONCLUSIONS: The results obtained are consistent with the proton sponge hypothesis and strongly suggest that the transfection activity of PEI vectors is due to their unique ability to avoid acidic lysosomes. 相似文献
6.
Francesca Orlandi Marcella Coronnello Cristina Bellucci Silvia Dei Luca Guandalini Dina Manetti Cecilia Martelli Maria Novella Romanelli Serena Scapecchi Milena Salerno Hayette Menif Ivan Bello Enrico Mini Elisabetta Teodori 《Bioorganic & medicinal chemistry》2013,21(2):456-465
As a continuation of previous research on a new series of potent and efficacious P-gp-dependent multidrug resistant (MDR) reversers with a N,N-bis(cyclohexanol)amine scaffold, we have designed and synthesized several analogs by modulation of the two aromatic moieties linked through ester functions to the N,N-bis(cyclohexanol)amine, aiming to optimize activity and to extend structure–activity relationships (SAR) within the series. This scaffold, when esterified with two different aromatic carboxylic acids, gives origin to four geometric isomers (cis/trans, trans/trans, cis/cis and trans/cis).The new compounds were tested on doxorubicin-resistant erythroleukemia K562 cells (K562/DOX) in the pirarubicin uptake assay. Most of them resulted in being potent modulators of the extrusion pump P-gp, showing potency values ([I]0.5) in the submicromolar and nanomolar range. Of these, compounds 2b, 2c, 3d, 5a–d and 6d, showed excellent efficacy with a αmax close to 1. Selected compounds (2d, 3a, 3b, 5a–d) were further studied to evaluate their doxorubicin cytotoxicity potentiation (RF) on doxorubicin-resistant erythroleukemia K562 cells and were found able to enhance significantly doxorubicin cytotoxicity on K562/DOX cells.The results of both pirarubicin uptake and the cytotoxicity assay, indicate that the new compounds of the series are potent P-gp-mediated MDR reversers. They present a structure with a mix of flexible and rigid moieties, a property that seems critical to allow the molecules to choose the most productive of the several binding modes possible in the transporter recognition site.In particular, compounds 5c and 5d, similar to the already reported analogous isomers 1c and 1d,29 are potent and efficacious modulators of P-gp-dependent MDR and may be promising leads for the development of MDR-reversal drugs. 相似文献
7.
Mark Pennington Aleksandra Gentry-Maharaj Chloe Karpinskyj Alec Miners Julie Taylor Ranjit Manchanda Rema Iyer Michelle Griffin Andy Ryan Ian Jacobs Usha Menon Rosa Legood 《PloS one》2016,11(11)
BackgroundThere is limited evidence on the costs of Endometrial Cancer (EC) by stage of disease. We estimated the long-term secondary care costs of EC according to stage at diagnosis in an English population-based cohort.MethodsWomen participating in UKCTOCS and diagnosed with EC following enrolment (2001–2005) and prior to 31st Dec 2009 were identified to have EC through multiple sources. Survival was calculated through data linkage to death registry. Costs estimates were derived from hospital records accessed from Hospital Episode Statistics (HES) with additional patient level covariates derived from case notes and patient questionnaires. Missing and censored data was imputed using Multiple Imputation. Regression analysis of cost and survival was undertaken.Results491 of 641 women with EC were included. Five year total costs were strongly dependent on stage, ranging from £9,475 (diagnosis at stage IA/IB) to £26,080 (diagnosis at stage III). Stage, grade and BMI were the strongest predictors of costs. The majority of costs for stage I/II EC were incurred in the first six months after diagnosis while for stage III / IV considerable costs accrued after the first six months.ConclusionsIn addition to survival advantages, there are significant cost savings if patients with EC are detected earlier. 相似文献
8.
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10.
Structural characterization of two aquaporins isolated from native spinach leaf plasma membranes 总被引:15,自引:0,他引:15
Fotiadis D Jenö P Mini T Wirtz S Müller SA Fraysse L Kjellbom P Engel A 《The Journal of biological chemistry》2001,276(3):1707-1714
Two members of the aquaporin family, PM28A and a new one, PM28C, were isolated and shown to be the major constituents of spinach leaf plasma membranes. These two isoforms were identified and characterized by matrix-assisted laser desorption ionization-mass spectrometry. Edman degradation yielded the amino acid sequence of two domains belonging to the new isoform. PM28B, a previously described isoform, was not found in our preparations. Scanning transmission electron microscopy mass analysis revealed both PM28 isoforms to be tetrameric. Two types of particles, a larger and a smaller one, were found by transmission electron microscopy of negatively stained solubilized proteins and by atomic force microscopy of PM28 two-dimensional crystals. The ratio of larger to smaller particles observed by transmission electron microscopy and single particle analysis correlated with the ratio of PM28A to PM28C determined by matrix-assisted laser desorption ionization-mass spectrometry. The absence of PM28B and the ratio of PM28A to PM28C indicate that these plasma membrane intrinsic proteins are differentially expressed in spinach leaves. These findings suggest that differential expression of the various aquaporin isoforms may regulate the water flux across the plasma membrane, in addition to the known mechanism of regulation by phosphorylation. 相似文献