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1.
Filippo Genovese Stefania Ferrari Giambattista Guaitoli Monica Caselli M. Paola Costi Glauco Ponterini 《Protein science : a publication of the Protein Society》2010,19(5):1023-1030
An ad hoc bioconjugation/fluorescence resonance energy transfer (FRET) assay has been designed to spectroscopically monitor the quaternary state of human thymidylate synthase dimeric protein. The approach enables the chemoselective engineering of allosteric residues while preserving the native protein functions through reversible masking of residues within the catalytic site, and is therefore suitable for activity/oligomerization dual assay screenings. It is applied to tag the two subunits of human thymidylate synthase at cysteines 43 and 43′ with an excitation energy donor/acceptor pair. The dimer–monomer equilibrium of the enzyme is then characterized through steady‐state fluorescence determination of the intersubunit resonance energy transfer efficiency. 相似文献
2.
Dinesh S. Bhoj 《Biometrical journal. Biometrische Zeitschrift》1989,31(3):279-288
Two statistics are proposed for testing the hypothesis of equality of the means of a bivariate normal distribution with unknown common variance and correlation coefficient when observations are missing on both variates. One of the statistics reduces to the one proposed by Bhoj (1978, 1984) when the unpaired observations on the variates are equal. The distributions of the statistics are approximated by well known distributions under the null hypothesis. The empirical powers of the tests are computed and compared with those of some known statistics. The comparison supports the use of one of the statistics proposed in this paper. 相似文献
3.
C. M. B. Duwel F. C. Visser M. J. van Eenige J. P. Roos 《Molecular and cellular biochemistry》1989,88(1-2):191-194
Summary Under normal and ischemic conditions backdiffusion of radiolabeled non-esterified fatty acids (NEFA) has been demonstrated. In the fasted normal canine heart the extraction fraction (EF) during interventions with glucose or lactate loading, vasodilation, and metabolic level augmentation was determined, and compared with the control EF. Backdiffusion alterations were deduced from the EF changes. After iv injection of 17-iodo-131 heptadecanoic acid (IHDA), 11 blood samples were drawn from aorta and coronary sinus in a time period of 60 minutes. In the control and vasodilation group the EF slowly decreased from 40 to 10%. In contrast, the EF in the noradrenaline group was constant. During glucose and lactate infusion the EF became negative within 10 min and remained negative. These results suggest that during physiological circumstances backdiffusion is determined by the metabolic level of the heart and its substrate availability. 相似文献
4.
A method has been developed for immobilisation of antisera on fresh plastic tubes through an immunochemical bridge. This type
of immobilisation has been shown to be more consistent than direct adsorption on plastic. Such immunochemically coated antisera
on plastic tube has been used in the development of a noncentrifugation radioimmunoassay. This assay system has been found
to be technically as sound as the conventional method. 相似文献
5.
E. Lendaro R. Ippoliti A. Brancaccio A. Bellelli B. Vallone G. Ivaldi G.V. Sciarratta C. Castello S. Tomova M. Brunori G. Amiconi 《生物化学与生物物理学报:疾病的分子基础》1992,1180(1):15-20
Hemoglobin Dallas, an α-chain variant with a substitution of lysine for asparagine at position 97(G4), was found to have increased oxygen affinity () and reduced Bohr effect (about 50%). Addition of allosteric effectors (such as 2,3-diphosphoglycerate, inositol hexakisphosphate and bezafibrate) led to a decrease in oxygen affinity and increase in cooperative energy. Kinetic studies at pH 7.0 and 20°C revealed that (i), the overall rate of oxygen dissociation is 1.4-fold slower than that for HbA and (ii), the carbon monoxide dissociation rate is unaffected. The abnormal properties of this hemoglobin variant can be atttributed to a more ‘relaxed’ T-state. 相似文献
6.
7.
Principal component analysis of compositional data 总被引:7,自引:0,他引:7
8.
9.
M. C. Léglise P. Darodes de Tailly J. L. Vignot M. A. Le Bot A.-M. Le Roux C. Riché 《Cell biology and toxicology》1996,12(1):39-53
A cellular model of hematopoiesis which would be more convenient than bone marrow (BM) progenitors and directly relevant to human pathology is needed in order to investigate xenobiotic toxicity. Human umbilical cord blood (HCB), previously shown to be able to repopulate BM, provides a powerful in vitro model of normal human hematopoiesis. In order to validate the use of normal HCB progenitors as targets for dose-related myelosuppression, we used clonogenic assays and expansion in a liquid culture of progenitor-enriched cell suspensions from HCB. A series of 8 reference molecules, doxorubicin, cytosine-arabinoside, 5-fluorouracil, 3-azido-3-deoxythymidine, acetylsalicyclic acid, sodium valproate and two cephalosporin antibiotics, were tested. In vitro 50% inhibition concentrations (IC50) were compared to those observed or reported with BM progenitors, and to the values of plasma concentrations from treated patients. HCB progenitors as in vitro targets for cytotoxic molecules were easy to access and handle, and their use was sensitive, specific and reproducible. They gave results similar to BM progenitors and allowed a qualitative approach to cellular metabolism and toxicity using morphological, flow cytometric and chromatographic methods.Abbreviations ARA-CC
cytosine arabinoside
- AS
acetylsalicylic acid
- AZTT
3-azido-3-deoxythymidine
- BFUU
burst-forming units
- BM
bone marrow
- CFU
colony-forming units
- DOXX
doxorubicin
- FU
5-fluorouracil
- glyAA
glyAcophorin A
- HCB
human umbilical cord blood
- IU
international units
- PCMEM
human placenta-conditioned medium
- VA
sodium valproate 相似文献
10.
Human cell lines derived from three epithelial carcinomas (CaSki, HeLa, SiHa), one B lymphoma (BL60), one promyelocytic (HL60), one monocytic (U937) leukemia, one chronic myelogenous leukemia (sensitive K562S; multichemoresistant K562R) and normal human skin fibroblasts were compared for their capacity of staining with rhodamine 123 (Rh 123) and their kinetics of dye exclusion. Cells were exposed for 30 min to 10 g/ml of Rh 123 in culture medium; fluorescence intensity was measured by flow cytometry immediately or 1, 2, 3 and 4 h after staining. The highest fluorescence intensity was observed in carcinoma cell lines; there was no incorporation in multichemoresistant K562R cells. Exclusion of Rh 123 was evaluated from 0 to 4 h, both by flow cytometry and by fluorimetry. Fluorescence intensity measured by flow cytometry decreased slightly in carcinoma and leukemia cells and rapidly in fibroblasts. In all cell lines Rh 123 exclusion was inhibited by 40 mol/L verapamil and 5 mmol/L probenecid. Thus, incorporation and exclusion of Rh 123 allows distinction between normal and tumoral cells; moreover, inhibition of exclusion by verapamil and probenecid favors the involvement of active cell membrane mechanisms in the exclusion process.Abbreviations PBS
phosphate-buffered saline
- Rh 123
rhodamine 123 相似文献