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排序方式: 共有341条查询结果,搜索用时 31 毫秒
1.
Annalisa Relini Silvia Torrassa Ranieri Rolandi Fabrizio Chiti Alessandra Gliozzi 《Biophysical journal》2010,98(7):1277-1284
We used tapping mode atomic force microscopy to study the morphology of the amyloid protofibrils formed at fixed conditions (low pH with high ionic strength) by self-assembly of the N-terminal domain of the hydrogenase maturation factor HypF. Although all protofibrils in the sample share a beaded structure and similar values of height and width, an accurate analysis of contour length and end-to-end distance and the comparison of experimental data with theoretical predictions based on the worm-like chain model show that two different populations of protofibrils are present. These populations are characterized by different physical properties, such as persistence length, bending rigidity and Young's modulus. Fluorescence quenching measurements on earlier globular intermediates provide an independent evidence of the existence of different populations. The finding that differences in mechanical properties exist even within the same sample of protofibrils indicates the presence of different subpopulations of prefibrillar aggregates with potentially diverse tendencies to react with undesired molecular targets. This study describes a strategy to discriminate between such different subpopulations that are otherwise difficult to identify with conventional analyses. 相似文献
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3.
A. Castagna D. Di Baccio R. Tognetti A. Ranieri L. Sebastiani 《Biologia Plantarum》2013,57(2):313-324
Information on plant responses to combined ozone and cadmium stresses are scarce and limited to herbaceous species. In this research, two poplar clones (I-214 and Eridano), differently sensitive to O3, were grown for 5 weeks in pots supplied with 0, 53.5, and 160.5 mg(Cd) kg?1 (soil d.m.) and then exposed to 15-d O3 fumigation (0.06 mm3 dm?3, 5 h a day). The effects of the two stressors, alone or in combination, on Cd, Ca, Fe, and Zn accumulation in above-nad below-ground organs, photosynthesis, leaf pigments, and accumulation of H2O2 and NO were investigated. Cadmium induced a reduction in stomatal conductance and a significant accumulation of H2O2 and NO in both clones nad negatively affected the carotenoid content in I-214. Ozone, on the other hand, counteracted Cd accumulation in the above-ground organs and significantly increased the xanthophyll de-epoxidation state indicating photoinhibition in O3-treated plants. Surprisingly, O3 alone or in combination with Cd decreased H2O2 accumulation in I-214. The NO production was generally stimulated by Cd, whereas it decreased following O3 exposure in I-214. The overall data indicate that Cd and O3 induced clone specific responses. Moreover, when they were applied in combination, antagonistic rather than synergistic effects were observed. 相似文献
4.
Concetta Saponaro Andrea Malfettone Girolamo Ranieri Katia Danza Giovanni Simone Angelo Paradiso Anita Mangia 《PloS one》2013,8(1)
Angiogenesis, which plays an important role in tumor growth and progression of breast cancer, is regulated by a balance between pro- and anti-angiogenic factors. Expression of vascular endothelial growth factor (VEGF) is up-regulated during hypoxia by hypoxia-inducible factor-1α (HIF-1α). It is known that there is an interaction between HIF-1α and BRCA1 carrier cancers, but little has been reported about angiogenesis in BRCA1-2 carrier and BRCAX breast cancers. In this study, we investigated the expression of VEGF and HIF-1α and microvessel density (MVD) in 26 BRCA1-2 carriers and 58 BRCAX compared to 77 sporadic breast cancers, by immunohistochemistry. VEGF expression in BRCA1-2 carriers was higher than in BRCAX cancer tissues (p = 0.0001). Furthermore, VEGF expression was higher in both BRCA1-2 carriers and BRCAX than the sporadic group (p<0.0001). VEGF immunoreactivity was correlated with poor tumor grade (p = 0.0074), hormone receptors negativity (p = 0.0206, p = 0.0002 respectively), and MIB-1-labeling index (p = 0.0044) in familial cancers (BRCA1-2 and BRCAX). The percentage of nuclear HIF-1α expression was higher in the BRCA1-2 carriers than in BRCAX cancers (p<0.05), and in all familial than in sporadic tumor tissues (p = 0.0045). A higher MVD was observed in BRCA1-2 carrier than in BRCAX and sporadic cancer tissues (p = 0.002, p = 0.0001 respectively), and in all familial tumors than in sporadic tumors (p = 0.01). MVD was positively related to HIF-1α expression in BRCA1-2 carriers (r = 0.521, p = 0.006), and, in particular, we observed a highly significant correlation in the familial group (r = 0.421, p<0.0001). Our findings suggest that angiogenesis plays a crucial role in BRCA1-2 carrier breast cancers. Prospective studies in larger BRCA1-2 carrier series are needed to improve the best therapeutic strategies for this subgroup of breast cancer patients. 相似文献
5.
Marianna Ranieri Grazia Tamma Annarita Di Mise Giuseppe Vezzoli Laura Soldati Maria Svelto Giovanna Valenti 《PloS one》2013,8(11)
In humans, gain-of-function mutations of the calcium-sensing receptor (CASR) gene are the cause of autosomal dominant hypocalcemia or type 5 Bartter syndrome characterized by an abnormality of calcium metabolism with low parathyroid hormone levels and excessive renal calcium excretion. Functional characterization of CaSR activating variants has been so far limited at demonstrating an increased sensitivity to external calcium leading to lower Ca-EC50. Here we combine high resolution fluorescence based techniques and provide evidence that for the efficiency of calcium signaling system, cells expressing gain-of-function variants of CaSR monitor cytosolic and ER calcium levels increasing the expression of the Sarco-Endoplasmic Reticulum Calcium-ATPase (SERCA) and reducing expression of Plasma Membrane Calcium-ATPase (PMCA). Wild-type CaSR (hCaSR-wt) and its gain-of-function (hCaSR-R990G; hCaSR-N124K) variants were transiently transfected in HEK-293 cells. Basal intracellular calcium concentration was significantly lower in cells expressing hCaSR-wt and its gain of function variants compared to mock. In line, FRET studies using the D1ER probe, which detects [Ca2+]ER directly, demonstrated significantly higher calcium accumulation in cells expressing the gain of function CaSR variants compared to hCaSR-wt. Consistently, cells expressing activating CaSR variants showed a significant increase in SERCA activity and expression and a reduced PMCA expression. This combined parallel regulation in protein expression increases the ER to cytosol calcium gradient explaining the higher sensitivity of CaSR gain-of-function variants to external calcium. This control principle provides a general explanation of how cells reliably connect (and exacerbate) receptor inputs to cell function. 相似文献
6.
Gerardo Abbandonato Barbara Storti Ilaria Tonazzini Martin Stöckl Vinod Subramaniam Costanza Montis Riccardo Nifosì Marco Cecchini Giovanni Signore Ranieri Bizzarri 《Biophysical journal》2019,116(3):477-486
The plasma membrane of cells has a complex architecture based on the bidimensional liquid-crystalline bilayer arrangement of phospho- and sphingolipids, which in turn embeds several proteins and is connected to the cytoskeleton. Several studies highlight the spatial membrane organization into more ordered (Lo or lipid raft) and more disordered (Ld) domains. We here report on a fluorescent analog of the green fluorescent protein chromophore that, when conjugated to a phospholipid, enables the quantification of the Lo and Ld domains in living cells on account of its large fluorescence lifetime variation in the two phases. The domain composition is straightforwardly obtained by the phasor approach to confocal fluorescence lifetime imaging, a graphical method that does not require global fitting of the fluorescence decay in every spatial position of the sample. Our imaging strategy was applied to recover the domain composition in human oligodendrocytes at rest and under treatment with galactosylsphingosine (psychosine). Exogenous psychosine administration recapitulates many of the molecular fingerprints of a severe neurological disease, globoid cell leukodystrophy, better known as Krabbe disease. We found out that psychosine progressively destabilizes plasma membrane, as witnessed by a shrinking of the Lo fraction. The unchanged levels of galactosyl ceramidase, i.e., the enzyme lacking in Krabbe disease, upon psychosine treatment suggest that psychosine alters the plasma membrane structure by direct physical effect, as also recently demonstrated in model membranes. 相似文献
7.
Enantioselective Preparation,Conformational Analysis and Absolute Configuration of Highly Substituted Aziridines 下载免费PDF全文
Giorgio Bencivenni Paolo Righi Lodovico Lunazzi Silvia Ranieri Michele Mancinelli Andrea Mazzanti 《Chirality》2015,27(12):875-887
The first example of organocatalytic aziridination reaction of α‐substituted‐α,β‐unsaturated ketones is presented. The reaction was found to be highly enantio‐ and diastereoselective, yielding N‐tosylated aziridines. Low‐temperature nuclear magnetic resonance (NMR) spectra allowed for the determination of the N‐inversion barrier, that was found to be quite lower with respect to unsubstituted aziridines. A thorough conformational analysis supported by low‐temperature NMR data allowed for the determination of the absolute configuration of the main stereoisomer by means of time‐dependent Density Functional Theory simulation of the electronic circular dichroism spectra. Chirality 27:875–887, 2015. © 2015 Wiley Periodicals, Inc. 相似文献
8.
Barbara Zerega Aldo Pagano Ada Pianezzi Valentina Ulivi Laura Camardella Ranieri Cancedda Fiorella Descalzi Cancedda 《Matrix biology》2004,23(1):35-46
Serum amyloid A (SAA) is synthesized by the liver during the acute phase. Local expression of SAA mRNA has been reported also in non-liver cells, a potential local source of SAA protein not related to the systemic acute phase response. SAA function has not been established yet. In the present study, we identified SAA as a protein expressed by chondrocytes and myoblasts in response to inflammatory stimula. In both cell systems, SAA mRNA and protein expression is strongly stimulated by bacterial lipopolysaccharide treatment. SAA mRNA expression is also enhanced during terminal differentiation of cells of the chondrogenic and myogenic lineage; mRNA is barely detectable in prechondrogenic cells and is highly expressed in differentiated hyperthrophic chondrocytes. An increased level of SAA mRNA was also observed in vivo when we compared mRNA extracted from tibiae of 10 day embryos, still fully cartilaginous, with tibiae from 18 day embryos, a stage when the endochondral ossification process has already started. p38 activation, a well-known event of the chondrogenesis signaling cascade, controls expression of SAA in cartilage following inflammatory stimuli. SAA secreted by stimulated chondrocytes is associated with cholesterol. Cholesterol is synthesized by the same chondrocytes and is also increased in inflammatory conditions. A role of SAA in cholesterol homeostasis in chondrocytes is proposed. 相似文献
9.
The V2 receptor antagonist tolvaptan raises cytosolic calcium and prevents AQP2 trafficking and function: an in vitro and in vivo assessment 下载免费PDF全文
Grazia Tamma Annarita Di Mise Marianna Ranieri Ari Geller Roberto Tamma Alberta Zallone Giovanna Valenti 《Journal of cellular and molecular medicine》2017,21(9):1767-1780
Tolvaptan, a selective vasopressin V2 receptor antagonist, is a new generation diuretic. Its clinical efficacy is in principle due to impaired vasopressin‐regulated water reabsorption via aquaporin‐2 (AQP2). Nevertheless, no direct in vitro evidence that tolvaptan prevents AQP2‐mediated water transport, nor that this pathway is targeted in vivo in patients with syndrome of inappropriate antidiuresis (SIAD) has been provided. The effects of tolvaptan on the vasopressin–cAMP/PKA signalling cascade were investigated in MDCK cells expressing endogenous V2R and in mouse kidney. In MDCK, tolvaptan prevented dDAVP‐induced increase in ser256‐AQP2 and osmotic water permeability. A similar effect on ser256‐AQP2 was found in V1aR ?/? mice, thus confirming the V2R selectively. Of note, calcium calibration in MDCK showed that tolvaptan per se caused calcium mobilization from the endoplasmic reticulum resulting in a significant increase in basal intracellular calcium. This effect was only observed in cells expressing the V2R, indicating that it requires the tolvaptan–V2R interaction. Consistent with this finding, tolvaptan partially reduced the increase in ser256‐AQP2 and the water permeability in response to forskolin, a direct activator of adenylyl cyclase (AC), suggesting that the increase in intracellular calcium is associated with an inhibition of the calcium‐inhibitable AC type VI. Furthermore, tolvaptan treatment reduced AQP2 excretion in two SIAD patients and normalized plasma sodium concentration. These data represent the first detailed demonstration of the central role of AQP2 blockade in the aquaretic effect of tolvaptan and underscore a novel effect in raising intracellular calcium that can be of significant clinical relevance. 相似文献
10.
Ranieri Rossi Daniela Giustarini Graziano Colombo Aldo Milzani Isabella Dalle-Donne 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2009,877(28):3467-3474
Aim of this study was to reconsider the previously suggested contribution of ketone bodies in causing oxidative damage in human red blood cells (RBCs) in the light of our recent findings demonstrating some methodological pitfalls that can occur during detection of hematic thiols. RBCs were incubated at 37 °C with 20 mM ketone bodies and analyzed with time for their content of glutathione, glutathione disulfide and S-glutathionylated proteins (in both the hemoglobin and membrane skeletal protein fraction). No changes in the concentrations of glutathione and its related forms were evidenced. Differently from previous reports, our results suggest that ketone bodies do not mediate generation of oxidative stress in human RBCs. 相似文献