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排序方式: 共有655条查询结果,搜索用时 31 毫秒
231.
Giulia Rossi Martina Placidi Chiara Castellini Francesco Rea Settimio D'Andrea Gonzalo Luis Alonso Giovanni Luca Gravina Carla Tatone Giovanna Di Emidio Anna Maria DAlessandro 《Molecules (Basel, Switzerland)》2021,26(6)
Infertility is a potential side effect of radiotherapy and significantly affects the quality of life for adolescent cancer survivors. Very few studies have addressed in pubertal models the mechanistic events that could be targeted to provide protection from gonadotoxicity and data on potential radioprotective treatments in this peculiar period of life are elusive. In this study, we utilized an in vitro model of the mouse pubertal testis to investigate the efficacy of crocetin to counteract ionizing radiation (IR)-induced injury and potential underlying mechanisms. Present experiments provide evidence that exposure of testis fragments from pubertal mice to 2 Gy X-rays induced extensive structural and cellular damage associated with overexpression of PARP1, PCNA, SOD2 and HuR and decreased levels of SIRT1 and catalase. A twenty-four hr exposure to 50 μM crocetin pre- and post-IR significantly reduced testis injury and modulated the response to DNA damage and oxidative stress. Nevertheless, crocetin treatment did not counteract the radiation-induced changes in the expression of SIRT1, p62 and LC3II. These results increase the knowledge of mechanisms underlying radiation damage in pubertal testis and establish the use of crocetin as a fertoprotective agent against IR deleterious effects in pubertal period. 相似文献
232.
Dr. Rebeca Lara Gonzalo Millán Prof. Dr. M. Teresa Moreno Prof. Dr. Elena Lalinde Elvira Alfaro-Arnedo Dr. Icíar P. López Dr. Ignacio M. Larráyoz Dr. José G. Pichel 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(63):15757-15772
The optical and biological properties of 2-(4-dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me2N-pbt)(C6F5)}L] [L=Me2N-pbtH 1 , p-dpbH (4-(diphenylphosphino)benzoic acid) 2 , o-dpbH (2-(diphenylphosphino)benzoic acid) 3 ), [Pt(Me2N-pbt)(o-dpb)] 4 , [{Pt(Me2N-pbt)(C6F5)}2(μ-PRnP)] [PR4P=O(CH2CH2OC(O)C6H4PPh2)2 5 , PR12P=O{(CH2CH2O)3C(O)C6H4PPh2}2 6 ] are presented. Complexes 1 – 6 display 1ILCT and metal-perturbed 3ILCT dual emissions. The ratio between both bands is excitation dependent, accomplishing warm-white emissions for 2 , 5 and 6 . The phosphorescent emission is lost in aerated solutions owing to photoinduced electron transfer to 3O2 and the formation of 1O2, as confirmed in complexes 2 and 4 . They also exhibit photoinduced phosphorescence enhancement in non-degassed DMSO due to local oxidation of DMSO by sensitized 1O2, which causes a local degassing. Me2N-pbtH and the complexes specifically accumulate in the Golgi apparatus, although only 2 , 3 and 6 were active against A549 and HeLa cancer cell lines, 6 being highly selective in respect to nontumoral cells. The potential photodynamic property of these complexes was demonstrated with complex 4 . 相似文献
233.
234.
Ferraz N Carnevia D Nande G Rossotti M Miguez MN Last JA Gonzalez-Sapienza G 《Analytical and bioanalytical chemistry》2007,389(7-8):2195-2202
Vitellogenin (VTG) and choriogenin (CHO) are valuable biomarkers of endocrine-disrupting compound (EDC) exposure in fish.
Existing immunoassays are limited to a few species, which restricts their use for the analysis of local wildlife sentinels.
Using C. facetum as a relevant South American model fish, this work presents a new strategy for the preparation of antibodies to VTG and CHO,
with zero cross-reactivity with fish serum components. Recombinant fragments of Cichlasoma facetum VTG (280-mer) and CHO (223-mer) were prepared by degenerate primer RT-PCR and expression in E. coli. Polyclonal and monoclonal antibodies prepared with these antigens were used to develop rapid dotblot assays for VTG and
CHO. Both the polyclonal and monoclonal antibodies prepared with the recombinant antigens reacted against the native proteins
adsorbed on to nitrocellulose allowing the set up of sensitive dotblot assays. The VTG assay was further validated with spiked
samples and purified native VTG. Exposure experiments with several estrogenic compounds revealed the potential of C. facetum as a sensitive biomonitor that produced measurable responses at concentrations of 100 ng L−1 of 17-beta-estradiol, 100 ng L−1 of ethynylestradiol, and 6.6 μg L−1 of nonylphenol. The approach described here may be applied to other native species to produce highly specific and sensitive
rapid tests. It may be particularly advantageous for species that cannot be kept in captivity or when homogeneous purification
of the immunizing proteins is particularly challenging. In conclusion, we present a novel approach to develop a strategy for
the generation of immunoassay reagents for vitellogenin (VTG) and choriogenin (CHO), which will facilitate regional studies
on the impact of endocrine-disrupting chemicals on local wildlife. 相似文献
235.
Evolution of a Unified Strategy for Complex Sesterterpenoids: Progress toward Astellatol and the Total Synthesis of (−)‐Nitidasin 下载免费PDF全文
Dr. Daniel T. Hog Dr. Florian M. E. Huber Dr. Gonzalo Jiménez‐Osés Dr. Peter Mayer Prof. Dr. Kendall N. Houk Prof. Dr. Dirk Trauner 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(39):13646-13665
Astellatol and nitidasin belong to a subset of sesterterpenoids that share a sterically encumbered trans‐hydrindane motif with an isopropyl substituent. In addition, these natural products feature intriguing polycyclic ring systems, posing significant challenges for chemical synthesis. Herein, the evolution of our stereoselective strategy for isopropyl trans‐hydrindane sesterterpenoids is detailed. These endeavors included the synthesis of several building blocks, enabling studies toward all molecules of this terpenoid subclass, and of advanced intermediates of our initial route toward a biomimetic synthesis of astellatol. These findings provided the basis for a second‐generation and a third‐generation approach toward astellatol that eventually culminated in the enantioselective total synthesis of (?)‐nitidasin. In particular, a series of substrate‐controlled transformations to install the ten stereogenic centers of the target molecule was orchestrated and the carbocyclic backbone was forged in a convergent fashion. Furthermore, the progress toward the synthesis of astellatol is disclosed and insights into some observed yet unexpected diastereoselectivities by detailed quantum‐mechanical calculations are provided. 相似文献
236.
Organocatalytic Asymmetric Addition of Naphthols and Electron‐Rich Phenols to Isatin‐Derived Ketimines: Highly Enantioselective Construction of Tetrasubstituted Stereocenters 下载免费PDF全文
Marc Montesinos‐Magraner Dr. Carlos Vila Rubén Cantón Prof. Dr. Gonzalo Blay Dr. Isabel Fernández Prof. Dr. M. Carmen Muñoz Prof. Dr. José R. Pedro 《Angewandte Chemie (International ed. in English)》2015,54(21):6320-6324
A quinine‐derived thiourea organocatalyst promoted the highly enantioselective addition of naphthols and activated phenols to ketimines derived from isatins. The reaction afforded chiral 3‐amino‐2‐oxindoles with a quaternary stereocenter in high yields (up to 99 %) with excellent enantioselectivity (up to 99 % ee). To the best of our knowledge, this transformation is the first highly enantioselective addition of naphthols to ketimines. 相似文献
237.
Alejandro Ortega‐Moux Carlos Alonso‐Ramos Alejandro Maese‐Novo Robert Halir Luis Zavargo‐Peche Diego Prez‐Galacho Iigo Molina‐Fernndez J. Gonzalo Wangüemert‐Prez Pavel Cheben Jens H. Schmid Jean Lapointe Danxia Xu Siegfried Janz 《Laser \u0026amp; Photonics Reviews》2013,7(2):L12-L15
Multimode interference couplers (MMIs) are fundamental building blocks in photonic integrated circuits. Here it is experimentally demonstrated, for the first time, a two‐fold length reduction in an MMI coupler without any penalty on device performance. The design is based on a slotted 2 × 2 MMI fabricated on a commercial silicon‐on‐insulator (SOI) substrate. The slot is implemented with a subwavelength grating (SWG) comprising holes fully etched down to the oxide cladding, thereby allowing single etch step fabrication. The device has been designed using an in‐house tool based on the Fourier Eigenmode Expansion Method. It has a footprint of only 3.5 μm x 23 μm and it exhibits a measured extinction ratio better than 15 dB within the full C‐band (1530 nm‒1570 nm). SWG engineered slots thus offer excellent perspectives for the practical realization of MMIs couplers with substantially reduced footprint yet with outstanding performance. 相似文献
238.
Onitsch C Rosspeintner A Angulo G Griesser M Kivala M Frank B Diederich F Gescheidt G 《The Journal of organic chemistry》2011,76(14):5628-5635
Despite the predominant electron donor character of p-phenylenediamine, our studies on extended p-phenylenediamine derivatives show that they can not only be chemically oxidized, giving well-known Wurster-type radical cations, but also be chemically reduced, giving radical anions. Making use of EPR/ENDOR spectroscopy and supported by DFT calculations, we were able to reveal the extent of π-electron delocalization in the paramagnetic species and to shed light onto the geometry and bond lengths. While for the radical anions spin was found to be mostly delocalized into the π-system, the radical cations can be described as essentially N-centered. Furthermore, we performed electrochemical characterizations using cyclic voltammetry to gain insight into the thermodynamics of the redox processes. The photophysical properties of the parent extended p-phenylenediamine were investigated by absorption, emission, and excitation spectroscopy. The fluorescence quantum yield and the excited-state lifetime of the neutral precursors in hexane and acetonitrile were determined to establish elementary differences originating from solvent effects. 相似文献
239.
Ayla M.C. Bizerra Tasso G.C. Montenegro Telma L.G. Lemos Maria C.F. de OliveiraMarcos C. de Mattos Iván LavanderaVicente Gotor-Fernández Gonzalo de GonzaloVicente Gotor 《Tetrahedron》2011,67(16):2858-2862
An enzymatic study has been performed in the search for synthetic routes to produce chloramphenicol derivatives through regioselective processes using lipases. Complementary transesterification and hydrolytic reactions have been carried to synthesize chloramphenicol regioisomers. Reaction parameters, such as biocatalyst, solvent, acyl donor, and temperature have been optimised in order to obtain chloramphenicol esters with high yields through acylation processes. Scale-up of the enzymatic reactions (1 g-scale at 0.25 M) and catalyst recycling (up to 10 cycles) have been successfully achieved. Furthermore, monoacylated derivatives at the more hindered secondary position could also be obtained employing hydrolysis processes. 相似文献
240.
Bargueño P Pérez de Tudela R Miret-Artés S Gonzalo I 《Physical chemistry chemical physics : PCCP》2011,13(3):806-810
Interactions which do not conserve parity might influence chiral compounds giving rise to a parity violating energy difference (PVED) that might have affected the evolution towards homochirality. However, this tiny effect predicted by electroweak-quantum chemistry calculations is easily masked by thermal effects, making it desirable to reach cold regimes in the laboratory. As an alternative route to the detection of the PVED, we study a simplified model of Bose-Einstein condensation of a sample of non-interacting chiral molecules, showing that it leads to a nonzero optical activity of the condensate and also to a subcritical temperature in the heat capacity, due to the internal structure of the molecule characterized by tunneling and parity violation. This predicted singular behavior found for the specific heat, below the condensation temperature, might shed some light on the existence of the thus far elusive PVED between enantiomers. 相似文献