1,721,004 research outputs found
Effects of intact and reduced reducing termini in heparin on structural and functional modifications of trypsin.
No full textFirst observation of very long-lasting emissive polarization in EPR spectra of Fremy's salt when reduced by ascorbic acid. An unusual aspect of the radical pair mechanism
No full textEmissive EPR spectral lines were observed in experiments dedicated to investigating the efficiency of ascorbic acid in reducing Fremy's salt. The emission was detected by CW spectroscopy and was exceptionally long lasting, being observed as long as 20 minutes. Fremy's salt emission lines were observed at the end of the redox reaction. The Fremy's salt absorption signal was totally quenched, and was replaced by an emission signal. This feature was observed under different experimental conditions. The inversion proceeded simultaneously for the three lines, which keep their relative intensities and hyperfine separation. The emission signal was also detected together with the normal absorption signal of ascorbyl free radical. No emission spectra were observed by using other nitroxides, or by using as reducing agent 1,4-dithio-DL-threitol instead of ascorbic acid. The observed spin polarization is accounted for on the basis of a Radical Pair Mechanism (RPM). The amount of polarization is related to the diffusion constant D, which decreases with increasing viscosity. By adding glycerol to the solution, enhanced polarisation was indeed observed, as expected, which confirms the proposed RPM polarisation mechanism. We report here for the first time, to our knowledge, the phenomenon of long- lasting emissive EPR lines
Targeting HER3 for cancer treatment: a new horizon for an old target
Full text linkHuman epidermal growth factor receptor 3 (HER3) is a member of the human epidermal growth factor receptors family, having as its main ligands neuregulins 1 and 2. Although its poor tyrosine kinase activity entails a weak oncogenic power on its own, HER3 can heterodimerize with HER2 and/or epidermal growth factor receptor (EGFR), leading to a drastic enhancement of transphosphorylation and activation of downstream signaling pathways, ultimately promoting oncogenesis, metastatic dissemination, and drug resistance. Given its ubiquitous expression across solid tumors, multiple efforts have been done to therapeutically target HER3 by blocking either the ligand binding domain or its dimerization with other receptors. Treatment with anti-HER3 monoclonal antibodies or bispecific antibodies, both as single agents and in combination with other compounds, unfortunately led to unsatisfactory results across several tumor types. The HER3-directed delivery of cytotoxic payloads through antibody-drug conjugates has recently demonstrated encouraging activity in several tumor types, however, suggesting a potential role for the therapeutic targeting of HER3 in cancer treatment
ON THE MACROMOLECULAR STRUCTURE AND MOLECULAR ACCESSIBILITY OF SWOLLEN MICROPOROUS RESINS - A COMBINED ESR-ISEC APPROACH
No full textA number of fairly hydrophilic microporous poly{ N,N-dimethylacrylamide-methylenebisacrylamide}resins (cross-linking degree from 1 to 8%) have been examined with two conceptually and experimentally quite ndependent
techniques that are able to provide information on the macromolecular structure and chemical accessibility of these materials in the swollen state. Electron spin resonance spectroscopy (ESR) and inverse steric exclusion chromatography (ISEC) gave quite consistent results in water, which are interpreted on the basis of a physico-mathematical model that fits the experimental data nicely. The resulting equation appears as a promising tool in the design of macromolecular materials for chemical and catalytic applications
A TIME-RESOLVED ELECTRON-SPIN-RESONANCE STUDY OF MOBILE EXCITED TRIPLET-STATES IN THE ANTHRACENE-1,2,4,5-TETRACYANOBENZENE CRYSTAL
No full textMobile triplet excitations (excitons) in the antracene-1,2,4,5-tetracyanobenzene crystal are studied by analysing the e.s.r. transient nutation signals after laser pulse excitation. Values of the relaxation times T1 and T2 are measured as a function of the temperature and of the crystal orientation. Their values are discussed in terms of the time modulation of the fine tensor caused by the exciton and the lattice motion. In the phase stable at low temperature the crystal structure consists of magnetically inequivalent stacks of anthracene and tetracyanobenzene molecules and a detailed analysis of the variation of T2–1 with the crystal orientation gives an estimate of the interaction between anthracene molecules in adjacent stacks
MOLECULAR ACCESSIBILITY IN INTERPENETRATING ORGANOMETALLIC POLYMER NETWORKS (IOPNS) - AN ESR EVALUATION
No full textInterpenetrating organometallic polymer networks can be seen as a new type of supported metal catalysts. They are prepared by the generation of a cross-linked organometallic copolymer (see figure) inside the macro- and microporous domains of organic and inorganic supports. Here, ESR analysis demonstrates that the microporous domains of such materials are accessible to molecules of substantial size
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
