Search results for "radical"
showing 10 items of 1401 documents
Physical exercise as an epigenetic modulator: Eustress, the "positive stress" as an effector of gene expression.
2012
Physical exercise positively influences epigenetic mechanisms and improves health. Several issues remain unclear concerning the links between physical exercise and epigenetics. There is growing concern about the negative influence of excessive and persistent physical exercise on health. How an individual physically adapts to the prevailing environmental conditions might influence epigenetic mechanisms and modulate gene expression. In this article, we put forward the idea that physical exercise, especially long-term repetitive strenuous exercise, positively affects health, reduces the aging process, and decreases the incidence of cancer through induced stress and epigenetic mechanisms. We pr…
Glutathione, oxidative stress and aging
1996
The free radical theory of aging proposes that the impairment in physiological performance associated with aging is caused by the detrimental effects of oxygen free radicals. This is interesting because it provides us with a theoretical framework to understand aging and because it suggests a rationale for intervention, i.e., antioxidant administration. Thus, the study of antioxidant systems of the cell may be very important in gerontological studies. Glutathione is one of the main nonprotein antioxidants in the cell which, together with its related enzymes, constitute the “glutathione system.” The involvement of glutathione in aging has been known since the early seventies. Several studies …
Idebenone in senile dementia of Alzheimer type: A multicentre study
1992
Idebenone is a new cerebro-active drug, effective in dementia disorders, particularly indicated in primary degenerative dementias, i.e. Alzheimer's disease. This new molecule acts as an electron trapper and a free radical scavenger protecting mitochondrial membranes from lipid peroxidation. A multicentric, double-blind trial of idebenone (45 mg twice daily orally) vs. placebo was carried out on 102 elderly patients affected by Alzheimer-type dementia of mild or moderate severity. Idebenone was administered for 4 consecutive months, 45 mg twice daily. Clinical evaluations were performed at the time of enrollment (t0) and monthly thereafter (t30, t60, t90 and t120) and at follow-up (t150 ). T…
On the formation of inclusion complexes at the solid/liquid interface of anchored temperature-responsive PNIPAAM diblock copolymers with γ-cyclodextr…
2017
The thermal responsive behavior of adsorbed layers of diblock copolymers of poly(N-isopropylacrylamide) (PNIPAAM) and poly((3-acrylamidopropyl)trimethylammonium chloride) (PAMPTMA(+)) with γ-cyclodextrin (γ-CD) at the solid/liquid interface has been investigated using three in situ techniques: null ellipsometry, quartz–crystal microbalance with dissipation monitoring, and neutron reflectometry. The measurements provided information about the adsorbed amounts, the layer thickness, hydration and viscoelastic properties, and the interfacial structure and composition. The copolymers adsorb to silica with the cationic PAMPTMA(+) blocks sitting as anchors in a flat conformation and the PNIPAAM ch…
Anal canal mixed adenoneuroendocrine carcinoma in a young patient misdiagnosed as anal abscess.
2021
Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are rare tumours of gastrointestinal tract, extremely rare in anal canal. We report a case of misdiagnosed MiNEN in a 38-year-old woman initially conservatively treated for a supposed anal fistula. In a second proctological evaluation, biopsy of the anal neoformation was performed and the histological specimen diagnosed a MiNEN. The complete staging showed a disseminate disease and the patient started a chemotherapy schedule. After 6 months, stable disease was revealed at the last imaging performed and radical surgery was offered to the patient that is actually on oncological follow-up without recurrence at 1 year.
First signals of electrochemically oxidized species of TTF and TMT-TTF : a study by in situ spectroelectrochemical FTIR and DFT calculations
2003
A first study by in situ FTIR spectroelectrochemistry of TTF and TTM-TTF has been undertaken. The oxidation, in this case, is caused only by electrochemistry, which constitutes a clear advantage over chemical oxidation since no side products are present in the solution. In this context, we obtained the signals of neutral, radical cation, and dication species of TTF and TTM-TTF. The experimental conditions were chosen in order to avoid the possible formation of π-dimer species and to obtain a satisfactory signal-to-noise ratio. A weak signal was detected for TTF and a stronger one for TTM-TTF. The changes induced by the oxidation process in the IR spectra of TTF and TTM-TTF have been analyze…
Highly stable defective TiO2-x with tuned exposed facets induced by fluorine: Impact of surface and bulk properties on selective UV/visible alcohol p…
2020
Abstract Titanium dioxide samples were prepared in the presence of different amounts of fluorine via hydrothermal method. It has been found that the presence of fluoride influenced the physico-chemical properties of TiO2 in various ways as polymorphic form stability, surface hydroxylation, generation of hydroxyl radicals under irradiation and formation of Ti3+ centers and oxygen vacancies. The generation rate of OH radicals was investigated by the photoluminescence technique in the presence of terephthalic acid. X-ray diffractometry indicated that fluorine stabilized the anatase TiO2. X-Ray photoelectron spectroscopy (XPS) revealed the presence of fluorine on the surface and the shift of th…
Ring splitting of azetidin-2-ones via radical anions
2012
The radical anions of azetidin-2-ones, generated by UV-irradiation in the presence of triethylamine, undergo ring-splitting via N-C4 or C3-C4 bond breaking, leading to open-chain amides. This reactivity diverges from that found for the neutral excited states, which is characterised by alpha-cleavage. The preference for beta-cleavage is supported by DFT theoretical calculations on the energy barriers associated with the involved transition states. Thus, injection of one electron into the azetidin-2-one moiety constitutes a complementary activation strategy which may be exploited to produce new chemistry.
Synthesis and antioxidant evaluation of novel silybin analogues
2006
In this work, we evaluated the antioxidant properties of the eight novel silybin analogues for their capacity to scavenge free radicals including superoxide anion radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in vitro. Compound 7d demonstrated an excellent antioxidant effect in scavenging superoxide anion free radical with an IC50 value of 26.5 microM, while the IC50 of quercetin (the reference compound) was 38.1 microM. Compounds 7b, 7e, 7h showed certain scavenging activities for both types of free radicals.
ESR and electrochemical studies of 2-acylpyridines and 6,6'-diacyl-2,2'-bipyridines.
2005
Abstract The ESR spectra of radicals obtained by electrolytic reduction of 2-acylpyridines and 6,6′-diacyl-2,2′-bipyridines were measured in dimethylsulfoxide (DMSO) and analyzed by quantum chemical calculations. The electrochemistry of these compounds was characterized using cyclic voltammetry, in DMSO solvent. The results showed a two step reduction mechanism, first wave was assigned to the generation of the correspondent free radical species, and the second wave was assigned to the dianion derivatives. AM1 and DFT calculations were performed to obtain the optimized geometries, theoretical hyperfine constants, and spin distributions, respectively. The theoretical results are in complete a…