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11.
Bogdan Alexandru Stoica Gabriela Bordeianu Raluca Stanescu Dragomir N. Serban Mihai Nechifor 《Journal of biological inorganic chemistry》2011,16(5):753-761
Allopurinol is a prodrug converted to oxypurinol by xanthine oxidase, a process followed by an efficient enzyme inhibition.
Using a lucigenin-enhanced chemiluminescence method, we found that, under alkaline conditions, superoxide radicals are produced
in large amounts in the first step of the interaction between the enzyme and the inhibitor. A comparison between lucigenin
and cytochrome c as final detectors revealed that only the chemiluminescence technique is able to detect the superoxide anions from allopurinol
oxidation. The allopurinol–xanthine oxidase–lucigenin system can be used for the quantification of various free-radical scavengers,
in particular superoxide dismutase mimics. Three manganese compounds from different structural classes [manganese(II) chloride,
manganese N,N′-bis(salicylidiene)ethylenediamine chloride, and manganese(III) meso-tetrakis(N-ethylpyridinium-2-yl)porphyrin] were compared at five concentrations (0.01, 0.1, 1, 10, and 100 μM). The method is fast,
16 times more sensitive than the cytochrome c assay at pH 10.1 and could be used for in vivo investigations avoiding the lucigenin redox cycle. If the concentrations of
the reagents are increased and Tween 20 is added, the method is also operative at pH 7.4. 相似文献
12.
Krastev DB Slabicki M Paszkowski-Rogacz M Hubner NC Junqueira M Shevchenko A Mann M Neugebauer KM Buchholz F 《Nature cell biology》2011,13(7):809-818
TP53 (tumour protein 53) is one of the most frequently mutated genes in human cancer and its role during cellular transformation has been studied extensively. However, the homeostatic functions of p53 are less well understood. Here, we explore the molecular dependency network of TP53 through an RNAi-mediated synthetic interaction screen employing two HCT116 isogenic cell lines and a genome-scale endoribonuclease-prepared short interfering RNA library. We identify a variety of TP53 synthetic interactions unmasking the complex connections of p53 to cellular physiology and growth control. Molecular dissection of the TP53 synthetic interaction with UNRIP indicates an enhanced dependency of TP53-negative cells on small nucleolar ribonucleoprotein (snoRNP) assembly. This dependency is mediated by the snoRNP chaperone gene NOLC1 (also known as NOPP140), which we identify as a physiological p53 target gene. This unanticipated function of TP53 in snoRNP assembly highlights the potential of RNAi-mediated synthetic interaction screens to dissect molecular pathways of tumour suppressor genes. 相似文献
13.
In this study we address the stability of integration of proteins in membranes. Using dynamic atomic force spectroscopy, we measured the strength of incorporation of peptides in lipid bilayers. The peptides model the transmembrane parts of alpha-helical proteins and were studied in both ordered peptide-rich and unordered peptide-poor bilayers. Using gold-coated AFM tips and thiolated peptides, we were able to observe force events which are related to the removal of single peptide molecules out of the bilayer. The data demonstrate that the peptides are very stably integrated into the bilayer and that single barriers within the investigated region of loading rates resist their removal. The distance between the ground state and the barrier for peptide removal was found to be 0.75 +/- 0.15 nm in different systems. This distance falls within the thickness of the interfacial layer of the bilayer. We conclude that the bilayer interface region plays an important role in stably anchoring transmembrane proteins into membranes. 相似文献
14.
15.
C.T. Dragomir D.T. Stefnescu I. Georgescu G.N. Stere L. Ciuca D. Ungureanu F. Tudor R. Chirvasie 《生物化学与生物物理学报:生物膜》1975,389(3):530-540
Xenon passage across the erythrocyte membrane was investigated by performing several types of tests. The effects of some enzyme inhibitors (ouabain, NaF, dinitrophenol, low temperature), representing various modifications of the mentioned transport phenomenon, led to the conclusion of the existence of a strong correlation between the cellular energetic metabolism (and, hence, the energy supply for membrane processes) and the xenon accumulation into the erythrocyte. The experimental data obtained indicate that the xenon concentration in the cell water exceeds the concentration in the incubation solution by about 20 %. The metabolic inhibitors practically equalise the xenon concentrations in the cell water and in the surrounding medium. The possible theoretical consequences of these facts are taken into account and analysed. 相似文献
16.
Hongtao Wang Andrei Dragomir Nida Itrat Abbasi Junhua Li Nitish V. Thakor Anastasios Bezerianos 《Cognitive neurodynamics》2018,12(4):365-376
Development of techniques for detection of mental fatigue has varied applications in areas where sustaining attention is of critical importance like security and transportation. The objective of this study is to develop a novel real-time driving fatigue detection methodology based on dry Electroencephalographic (EEG) signals. The study has employed two methods in the online detection of mental fatigue: power spectrum density (PSD) and sample entropy (SE). The wavelet packets transform (WPT) method was utilized to obtain the \(\theta \) (4–7 Hz), \(\alpha \) (8–12 Hz) and \(\beta \) (13–30 Hz) bands frequency components for calculating corresponding PSD of the selected channels. In order to improve the fatigue detection performance, the system was individually calibrated for each subject in terms of fatigue-sensitive channels selection. Two fatigue-related indexes: (\(\theta +\alpha \))/\(\beta \) and \(\theta \)/\(\beta \) were computed and then fused into an integrated metric to predict the degree of driving fatigue. In the case of SE extraction, the mean of SE averaged across two EEG channels (‘O1h’ and ‘O2h’) was used for fatigue detection. Ten healthy subjects participated in our study and each of them performed two sessions of simulated driving. In each session, subjects were required to drive simulated car for 90 min without any break. The results demonstrate that our proposed methods are effective for fatigue detection. The prediction of fatigue is consistent with the observation of reaction time that was recorded during simulated driving, which is considered as an objective behavioral measure. 相似文献
17.
Dragomir Marisavljevi Peter Antunovi Predrag Milji Milena Panti 《Cancer immunology, immunotherapy : CII》1998,15(4):275-278
A 71-year-old male patient with atypical myelodysplastic syndrome showing monosomy 7 is described. He presented with severe
foot pains, trophic skin and nail changes, loss of distal pulses, all compatible with peripheral arterial occlusive disease.
He had completely normal blood counts and no bleeding tendency. Prolonged bleeding time was disclosed by chance, during routine
haemostatic studies. An acquired platelet dysfunction was considered, with prolonged bleeding time and large platelets that
failed to aggregate in response to arachidonic acid and that had impaired response to collagen and adrenaline. The bone marrow
was hypercellular, with numerous dysplastic megakaryocytes and two other slightly dysplastic myeloid lines. Cytogenetic analyses
of the bone marrow cells showed a mosaic karyotype: 46,XY/45,XY,-7. On angiography, bilateral thrombosis of the iliac, superficial
femoral and popliteal arteries was disclosed. The patient was prepared with platelet transfusions. Arterial thrombectomy and
amputation of the left calf were performed. Ten months later, his blood counts showed mild pancytopenia. He died at home.
The authors discuss some clinical and pathogenetical aspects of such presentations of myelodysplastic syndromes. 相似文献
18.
Teiber JF Billecke SS La Du BN Draganov DI 《Archives of biochemistry and biophysics》2007,461(1):24-29
Mammalian paraoxonases (PONs 1, 2 and 3) are a highly conserved family of esterases, with uncertain physiological functions and natural substrates. Here we characterize the ability of purified recombinant human PONs to hydrolyze estrogen esters, a class of compounds previously not known to be PON substrates. PONs hydrolyzed estrogen mono- and diesters at position 3 of the steroid A-ring. Diesters were better substrates for the PONs and were very efficiently hydrolyzed, particularly by PON3. Esters at position 17 were not cleaved by the PONs unless an adjacent double bound was present. Purified human serum butyryl cholinesterase also hydrolyzed estrogen esters, however it preferably hydrolyzed the mono-esters. The ability of the PONs' to effectively hydrolyze a variety of estrogen esters provides further insight into the structure of their active sites and suggests that natural compounds with aromatic ester groups might be relevant substrates for the PONs. 相似文献
19.
C T Dragomir I Margineanu D Ungureanu G Filipescu A Barbier D Alexianu 《Physiological chemistry and physics》1980,12(1):69-76
ATP splitting activity is progressively reduced with increasing heavy water (D2)) concentration. In contrast, sarcomere shorteining inhibition produced by D2O does not significantly depend on its concentration. Even at low concentration, the presence of D2O does reduce the excessive accumulation of radioactive sodium within glycerinated frog muscle. These heavy water effects on muscular contraction and soidum distribution can be interpreted to indicate adsorbed water within the cells. Evaluation of these experimental results in terms of Gibbs free enthalpy of binding at the adsorption sites of D20 or H20 is in good agreement with the data in the literature. 相似文献
20.
Coordination of DNA synthesis and replicative unwinding by the S-phase checkpoint pathways 总被引:2,自引:0,他引:2
The process of DNA replication includes duplex unwinding, followed immediately by DNA synthesis. In eukaryotes, DNA synthesis is disturbed in damaged DNA regions, in replication slow zones, or as a result of insufficient nucleotide level. This review aims to discuss the mechanisms that coordinate DNA unwinding and synthesis, allowing replication to be completed even in the presence of genomic insults. There is a growing body of evidence which suggests that S-phase checkpoint pathways regulate both replicative unwinding and DNA synthesis, to synchronize the two processes, thus ensuring genome stability. 相似文献