Number Of Free Radicals Research Articles

Effect of Dietary Selenium Supplementation on Morphology and Antioxidant Status in Testes of Goat

The fitness of animal has an enormous influence on its reproductive capability, nowadays feeding of microelements is practiced in many feed formulations because micro-nutrient possesses strong influence on animal’s reproductive ability. The male generative zone produces spermatozoa which needs a little number of free radicals for the maturation as well as for smooth fertilization. Whereas the raised level of these free radicals disturbs the entire process of sperm formation and also lead to infertility. The Selenium is a micro nutrient which naturally possess some enzymes and selenoproteins which diminish manufacture of unnecessary free radicals by acting as an antioxidant. Subsequently, it protects male gamete from destruction triggered by oxidative stress. Selenium also assistance in maintenance of semen quality by declining construction of atypical spermatozoa. Additionally, some studies have revealed that it possesses striking influence on both gross and histological characteristics of male reproductive organ, feeding this mineral improved circumference, size, the mass of the testis and speed up sperm construction by means of having a solid effect on seminiferous tubules histology. Hence, selenium shortage can cause infertility and further reproductive syndromes.

Application of luminescence for estimating the efficiency of photocatalysts

Capabilities of new approaches in luminescence applications for estimating the quality of photocatalysts have been studied. Since photoluminescent processes are chain ones and initiated by free radicals, luminol and other indicators can be used to determine the efficiency of photocatalysts: the higher is the intensity of luminescent glow, the more is the number of free radicals in the system and the higher is the efficiency of photocatalyst. In some cases, by using special techniques it is possible to study the accumulation of superoxide radicals, hydroxyl radicals, and hydrogen peroxide in the system.

Variations in surface and electrical properties of polytetrafluoroethylene film after plasma-induced grafting of acrylic acid

Polytetrafluoroethylene (PTFE) film was graft-polymerized with acrylic acid (AAc) via a low-temperature plasma technique. The effect of plasma treatment parameters (radio-frequency power and treatment time) on the spin number of free radicals in PTFE film was examined. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and atomic force microscopy were employed to characterize the chemical structure, surface composition, and microstructure of the original PTFE and PTFE-g-PAAc films, respectively, in order to verify the successful graft polymerization of AAc onto a PTFE film surface. Thermogravimetric analysis illustrated that the thermal stability of bulk PTFE film remains unchanged after graft modification. Water contact angle measurements confirmed that the hydrophilicity of PTFE-g-PAAc film was effectively improved as compared to the original PTFE film. The dielectric constant (epsilon(r)) of PTFE-g-PAAc (GD = 218 mu g/cm(2)) film remained invariable, compared to that of the unmodified PTFE film. Nevertheless, the dielectric loss (tan delta) of PTFE film increased considerably, from 0.0002 (GD = 0 mu g/cm(2)) to 0.0073 (GD = 218 mu g/cm(2)), which might be due to the increase in surface polarity and moisture resulting from AAc graft modification. In addition, the surface electrical resistance (R-s) of PTFE film decreased slightly, from 131.89 (GD = 0 mu g/cm(2)) to 110.28 Omega cm(2) (GD = 218 mu g/cm(2)) after surface modification, but still retained its inherent high impedance.

Effect of Electron Beam Irradiation on Remaining Activity of Lyophilized Acid Phosphatase with Water-Binding and Non-Water–Binding Additives

The ability of various additives to protect lyophilized acid phosphatase against the deleterious effects of electron beam irradiation was investigated. For this purpose, ingredients with water-binding (e.g., lactose and sucrose) and non-water-binding (e.g., mannitol and polyvinylpyrrolidone) properties were used. The reconstituted activity of acid phosphatase was found to dramatically decrease when the irradiation dose overcame a threshold, which is formulation-dependent. That difference has been related to a different affinity with water of the various additives and, thus, with the water-binding property of the formulation. The deactivation of acid phosphatase against irradiation seems to be directly correlated with the residual moisture of the lyophilized product and inversely correlated with the fraction of water strongly confined within the solid. In particular, the highest protection of the enzyme against irradiation was given by a lactose-containing formulation, while the polyvinylpyrrolidone-based formulation gave the lowest protection. This finding was also confirmed by the fact that the number of free radicals generated by irradiation directly depends on the amount of water that is not strongly bound to the product surface. Overall, water-binding additives are preferable to non-water-binding ones in order to protect the active ingredients against irradiation. Follow-up studies should focus on the structural properties of confined water and thus on its ability to preserve the active ingredient against the deleterious effects of drying and irradiation.

Study of electron spin resonance and viscosity for hemoglobin polymer after arsenic trioxide and gamma irradiation treatment

The present work aimed to study the intensity of electron spin resonance (ESR) of hemoglobin rat's polymer and changes in rheological properties (viscosity). This study included five groups: control, irradiation with single dose of 5 Gy gamma irradiation, intraperitoneal injection with single dose of arsenic trioxide (As2O3) 10 mg/kg body weight, As2O3 followed by 5 Gy and 5 Gy followed by As2O3. The results of ESR spectroscopy indicated that the intensity increases significantly for As2O3 and non-significantly with 5 Gy of gamma radiation compared with control, which indicated an increase in the number of free radicals. Injection with As2O3 after and before 5 Gy resulted in non-significant decrease which given rise to a decrease in the number of free radicals. there was significant decrease in viscosity for 5 Gy at different shear rates (11.3–375 sec−1), viscosity for As2O3 injection group showed non-significant decrease, and non-significant increase in case of 5 Gy followed by As2O3 injection, significant decrease at high shear rate in case of 5 Gy followed by As2O3. These results concluded that 5 Gy followed by As2O3 showed some sort of repair in the function of rats hemoglobin rather than injection with As2O3 and 5 Gy both individually.

The intrinsic mechanism of methane oxidation under explosion condition: A combined ReaxFF and DFT study

In order to develop efficient suppression techniques and isolation materials for gas explosion, it is greatly vital to understand the intrinsic mechanism of gas explosion at atomic level. The methane explosion process was systematically explored by reactive force field molecular dynamics (MD) simulation and density function theory (DFT) calculations. The results show that the initiation step of the gas explosion process is mainly induced by OH free radical, and the chain transfer process is primarily carried by the conversion from HO2 to OH radical. The number of free radicals, such as CH3, HO2 and OH, greatly affect the reaction velocity during the gas explosion process. These results not only identify the critical reaction intermediates and main radical carriers of methane explosion process, but also they will provide significant theoretical guide for development of the novel and efficient gas explosion suppression methods and isolation materials.

Determination of free radicals and flavan-3-ols content in fermented and unfermented teas and properties of their infusions

The objective of this study was to analyse selected brands of fermented (red and black) and unfermented (white and green) teas for free radical content with the use of electron paramagnetic resonance (EPR) spectroscopy and for contents of flavan-3-ols by means of high-performance liquid chromatography. Analyses were also conducted for the polyphenolic profile of infusions of the analysed teas (with the Folin–Ciocalteu’s method) and their antioxidant activity (in reaction with a DPPH radical) at three brewing times (5, 10 and 15 min). The obtained results showed the possibility of using rapid spectroscopic method EPR to evaluate the oxidative changes in tea leaves caused by enzymatic fermentation. The number of free radicals in teas was negatively correlated with contents of flavan-3-ols, (−)-EGCG in particular. The main signals observed in EPR spectra of teas were attributed to semiquinone radicals; however, also signals attributed to carbohydrate radicals were detected. Regarding unfermented teas, it was ascertained that teas with the highest content of flavan-3-ols, (−)-EGCG in particular, were characterised by the lowest content of semiquinone radicals and a high content of carbohydrate radicals. The group of fermented teas demonstrated to contain mainly semiquinone radicals. The total phenolic content and antioxidant activity of the tea infusions were strongly diversified depending on the kind and brand of tea as well as on the extraction time. The predominating flavan-3-ol in the analysed teas was epigallocatechin gallate (−)-EGCG, the content of which was additionally highly correlated with the antioxidant activity of the tea infusions.

A synergistic approach to the polydispersity of polymers

A scheme for calculating polydispersity coefficients of polymers during chain propagation in living polymerization is proposed on the basis of the synergistic approach (the master equation) with allowance for fluctuations in the number of free radicals at the stage of initiation. The molecular-mass-distribution function of living chains is calculated. The form of this function is shown to be dependent on the ratio between the constants of the elementary stages of chain initiation and propagation.

ESR Dosimetric Study on Gamma Induced Radicals in DL-Ornithine Hydrochloride

DL-ornithine hydrochloride rods (3 ×10 mm) were studied to be a radiation sensitive material for EPR dosimetry. The rods have specified EPR signal developed under irradiation and its intensity increases with the increase in absorbed dose. The intensity also affected by the concentration of DL-ornithine in the rods. The prepared rods can be used in the dose range from 0.5 - 50 kGy. The obtained number of free radicals per 100 eV (G value) was found to be 0.3551 ± 0.0333. The hyperfine (hf) coupling constant is 2.325 mT at g-factor 2.033. The rods have the advantage of negligible humidity effects during irradiation. The pre and post- irradiation stability was found to be satisfactory.

New developments of the effect of melatonin on reproduction

In the past decades, a lot of advances in understanding the biochemistry and physiology of the pineal gland have been made. There is evidence that it interacts with many endocrine as well as non-endocrine tissues to influence their metabolic activity modulating many organs and functions. Melatonin is secreted by the pineal gland in the brain and plays an important role in regulating the neuroendocrine system. This hormone is one of the major role players in the regulation of the circadian sleep-wake cycle. It is normally released from the pineal gland during the night in response to environmental changes in light. Studies have shown that melatonin plays a role in the regulation of many reproductive processes such as puberty, gonadal function, and pregnancy. Beside these, melatonin has been shown to be able to directly neutralize a number of free radicals and reactive oxygen and nitrogen species. The main objective of this review is to provide comprehensive information about the new developments in melatonin research regarding its role in reproduction. A review of international scientific literature was done and a question-and-answer format was used in an attempt to convey comprehensive information in a simple manner. This review discusses evidence currently available relating to the effect of melatonin on reproductive processes. It deliberates the mechanism of action of melatonin, its effect on puberty, testicular and ovafunction, pregnancy, and oxidative stress. A growing body of scientific evidence is suggesting that melatonin plays an important role in reproductive function. It is therefore imperative to highlight the beneficial effects of this hormone in improving the reproductive processes.

Genome-wide transcriptome profiling of ROS scavenging and signal transduction pathways in rice (Oryza sativa L.) in response to different types of ionizing radiation

Ionizing radiation directly and indirectly affects gene expression within the plant genome. To access the antioxidant response of rice to different types of ionizing radiation, rice seeds were exposed to gamma-ray, cosmic-ray and ion beam radiation. Exposure to ionizing radiation dramatically decreased the shoot length in all plants but not the root length compared with a non-irradiated plant. Electron spin resonance, confirmed that the number of free radicals in cell was greatly increased by different types of ionizing radiation. The measurement of the MDA, chlorophyll, carotenoids contents and activity of antioxidant enzymes revealed that gamma-ray and cosmic-ray, but not ion beam, ionization deceased chlorophyll and carotenoids contents, while all three ionization treatments increased the activities of peroxidase, ascorbate peroxidase, and superoxide dismutase compared with the non-irradiated plants. Microarray analysis using Affymetrix GeneChip was used to establish the gene transcript profiles of rice genes regarding ROS scavenging and signal transduction pathways after ionization treatment. Many of the rice genes involved in ROS scavenging and signal transduction pathways showed induction or repression that had increased more than twofold after ionization treatment. In particular, genes associated with electron transport, such as NADPH oxidase-like and alternative oxidase, were often down-regulated by more than twofold in response to the ionization treatments. In our transcriptomic profile analysis, we confirmed that the expression of rice genes associated with ROS scavenging and signal transduction pathways was induced or repressed to different degrees by the different types of ionizing radiations, as in other environmental stresses.

P32 H2S post-conditioning protect rat myocardium from ischemia reperfusion injury involved in endoplasmic reticulum stress

Background In the process of myocardial ischemia and reperfusion (I/R), hypoxia, deficient glucose, ATP depletion, calcium overload and a large number of free radicals can induce endoplasmic reticulum stress (ERS), and excessive endoplasmic reticulum stress will induce apoptosis and increase the myocardial I/R injury. Recent studies have found that the new endogenous gaseous signal molecule hydrogen sulfide (H 2 S) was involved in myocardial ischemia postconditioning and alleviated ischemia/reperfusion injury, and that exogenous H 2 S postconditioning has a protective effect on the isolated heart ischemia–reperfusion injury. However, the precise mechanism that hydrogen sulfide protect heart from myocardial I/R injury remain unclear. Our study aimed to investigate whether hydrogen sulfide protect myocardium from I/R injury by inhibiting the I/R-induced excessive endoplasmic reticulum stress in rat heart. Methods Sprague–Dawley rats were randomly divided into 5 groups ( n = 12 in each): Sham group, I/R group, I/R + NaHS (sodium hydrosulfide, an H 2 S donor) groups (H 2 S post-conditioning group), I/R + TUDCA (Tauro Ursodesoxy Cholic Acid, an endoplasmic reticulum stress blocker) group and I/R + TUDCA + NaHS group. NaHS 14 μmol/kg and TUDCA 25 mg/kg were injected i.p. after 30 min of myocardial ischemia and within reperfusion 10 min. The myocardial I/R rats were subjected to ischemia by 30 min of coronary artery branch of left anterior descending occlusion followed by 2 h of reperfusion. During myocardial I/R, electrocardiogram (ECG, lead II) was monitored continuously, arrhythmias rating was assessed according to the standard of Lambeth meeting. At the end of the reperfusion, myocardial infarct size was examined by triphenyltetrazolium chloride (TTC) staining, serum concentration of H 2 S was determined with a spectrophotometer, myocardial apoptosis was detected by TUNEL and the protein levels of GRP78, CHOP were assayed by Western blotting. Results Compared with the Sham group, the H 2 S concentration in the serum of the I/R group was significantly decrease ( p p p 2 S concentrations of I/R + NaHS group were significantly increased ( p 2 S into rat/H 2 S post-conditioning could decrease the arrhythmia score and reduce myocardial infarct size significantly. The apoptotic rate was also decreased by exogenous H 2 S post-conditioning. The decrease of GRP78 and CHOP protein level in I/R could be partly reversed by H 2 S post-conditioning ( p Conclusions NaHS postconditioning could protect rat myocardiocytes from myocardial ischemia–reperfusion injury partly by inhibition of H 2 S on excessive endoplasmic reticulum stress induced by myocardiac ischemia/reperfusion.

A mathematical model of the evolution of free radical concentrations in a cell under ionizing radiation

A probabilistic mathematical model that describes the evolution of the free radical concentration in a cell under ionizing radiation is proposed. The model is of a stochastic character and allows one to describe the generation of free radicals in the process of radiolysis, as well as the interaction between the radicals of different types and between the radicals and the cell constituents (the latter is responsible for radiobiological effect). The possibility of the presence in the cell of a certain equilibrium quantity of radicals of nonradiative origin at the moment that the irradiation begins is taken into account. The results thus obtained show that under certain values of the model’s free parameters the total number of free radicals in a cell under radiation may decrease. This effect can explain the “positive” influence of small doses of ionizing radiation.

Radical-scavenging Activity of the Reaction Products of Isoeugenol with Thiol, Thiophenol, Mercaptothiazoline or Mercaptomethylimidazole Using the Induction Period Method

The reaction products in the presence of Lewis acid of isoeugenol (1) with ethanethiol, thiophenol, 2-mercaptothiazoline or 2-mercapto-1-methylimidazole (ISO-S1-ISO-S-4) were obtained. The radical-scavenging activity of these compounds was investigated using the induction period method for polymerization of methyl methacrylate (MMA) initiated by thermal decomposition of 2,2'-azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO) and monitored by differential scanning calorimetry (DSC). For BPO, the stoichiometric factor (number of free radicals trapped by one mole of antioxidant moiety, n) declined in the order isoeugenol (1.8) > ISO-S-1 (1.6) > ISO-S-2 (1.2) > ISOS- 3 (0.9) > ISO-S-4 (0.3), whereas for AIBN, their n values were about 1, except for ISOS- 3 (0.6). The ratio of the rate constant of inhibition to that of propagation (k(inh)/k(p)) for BPO declined in the order ISO-S-4 (56) > ISO-S-3 (15) > ISO-S-2 (11) >ISO-S-1 (9) > isoeugenol (8). Similarly, for AIBN the k(inh)/k(p) of the reaction products (33-57) was greater than that of isoeugenol (31). The reaction products of isoeugenol with a SH group showed greater inhibition rate constants (kinh) than the parent compound isoeugenol.

Framework Analysis for the Carcinogenic Mode of Action of Nitrobenzene

Nitrobenzene (CASRN: 98-95-3) has been shown to induce cancers in many tissues including kidney, liver, and thyroid, following chronic inhalation in animals. However, with a few exceptions, genotoxicity assays using nitrobenzene have given negative results. Some DNA binding/adduct studies have brought forth questionable results and, considering the available weight of evidence, it does not appear that nitrobenzene causes cancer via a genotoxic mode of action. Nitrobenzene produces a number of free radicals during its reductive metabolism, in the gut as well as at the cellular level, and generates superoxide anion as a by-product during oxidative melabolism. The reactive species generated during nitrobenzene metabolism are considered candidates for carcinogenicity. Furthermore, several lines of evidence suggest that nitrobenzene exerts its carcinogenicity through a non-DNA reactive (epigenetic) fashion, such as a strong temporal relationship between non-, pre-, and neoplastic lesions leading to carcinogenesis. In this report, we first describe the absorption, distribution, metabolism, and excretion of nitrobenzene followed by a summary of the available genotoxicity studies and the only available cancer bioassay. We subsequently refer to the mode of action framework of the U.S. Environmental Protection Agency's 2005 Guidelines for Carcinogen Risk Assessment as a basis for presenting possible modes of action for nitrobenzene-induced cancers of the liver, thyroid, and kidney, as supported by the available experimental data. The rationale(s) regarding human relevance of each mode of action is also presented. Finally, we hypothesize that the carcinogenic mode of action for nitrobenzene is multifactorial in nature and reflective of free radicals, inflammation, and/or altered methylation. †These authors contributed equally to this work.

The effect of treatment of activated carbon by H2O2 or HNO3 on the decomposition of pentachlorobenzene

We investigated the reactivity between modified activated carbon and pentachlorobenzene (P5CBz) to better understand how the nature of activated carbon affects the decomposition of chlorinated aromatics. To modify and control the overall characteristics, activated carbon was treated with either nitric acid or hydrogen peroxide. According to ESR, the number of free radicals on the activated carbon was found to increase in response to a treatment in 70% nitric acid at 70°C for 24h. Additionally, certain functional groups, such as carboxyl and hydroxyl groups, are believed to have formed on the surface of the activated carbon as indicated by the results of FT-IR and XPS. The catalytic decomposition experiments involving P5CBz were conducted using a pulse-type, packed-bed reactor. Using the activated carbon that was previously treated with nitric acid for 24h, P5CBz molecules were completely decomposed at a temperature of 350°C, irrespective of either an air or nitrogen atmosphere. The mechanism of decomposition of P5CBz depends on the kind of oxygen functional group and free radicals present.

SU-FF-T-233: Example Responses of the Free Radical Diagnostic Alpha-Diphenyl-Piorhylhydrasy (DPPH) to a Conventional Dose Rate and a Very High Dose Rate Electron Beam

Alpha‐Diphenyl‐piorhylhydrasy, or DPPH, a free radical diagnostic, can be used as a dosimeter when it is suspended in a medium that is at least partially translucent. The amount of color change of DPPH from a nominal purple to yellow is an indication of the number of free radicals created. Purpose: As a preliminary investigation, we examined two different combinations of DPPH and the response to two different 6 MeV electron beams.Method and Materials: The combinations consisted of DPPH with water and with bovine serum albumen, (BSA). The two electron beams were from a Varian 2100EX with a conventional dose rate, and from a modified Varian Saturne SL42 with a very high dose rate. The Saturne was operated in 6 MV photon mode with its target and monitor chambers removed so the dose rate of the electron beam was over 3000 times higher than the conventional dose rate. The peak instantaneous dose rate, which occurs when an “electron bunch” impinges, is over 107 Gy/min for the SL42. Approximately 2 ml of the DPPH combinations were irradiated in 3 cm diameter culture dishes to different doses. Controls were taken and exposed to the same environmental conditions as the irradiated dishes. Rapid color change occurred within seconds of irradiation, and the color change was analyzed on a Power Wave X Bio‐Tek analyzer. Results/Conclusions: Although there is more scatter in the preliminary data for the SL42 irradiation, the response from both beams can be approximated as being linear up to the maximum dose measured, 6000 cGy. The slope of the response for both beams is about the same, which indicates that the free radical activity is not heavily influenced by the dose rate within this range. The possibilities of using DPPH as a “biological” dosimeter will be discussed.

Radiation induced radical in barium sulphate for ESR dosimetry: a preliminary study

Barium sulphate (BaSO 4) was irradiated by γ-rays and analyzed with electron spin resonance (ESR) to study radiation induced radicals for materials as radiation dosimeter. The ESR spectrum for the radical species is characterized by a hole-type center with g factor of 2.019, 2.0127 and 2.0103 and electron-type center with g factor of 2.0039, 2.0025 and 2.0001. The dosimetric signal with splitting factors of g=2.0039 is ascribed to SO 3 − radicals and 5 G linewidth. The response to γ-ray dose ranging from 5 to 10 3 Gy, energy dependence calculation and the thermal stability have been studied. The number of free radicals per 100 eV ( G-value) was obtained to be 0.25 ± 0.06 and 0.9 ± 0.18 for BaSO 4 and alanine, respectively. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 325 ± 60 days, and 0.50 ± 0.09 eV respectively.

ESR dosimetric properties of modern coral reef

Modern coral reef samples from Egypt were irradiated with 60Coγ-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum for the radical species in unirradiated coral is characterized by four signals with spectroscopic splitting factors of g=2.0056, 2.0030, 2.0006 and 1.997. The signal at g=2.0006±0.0005 is ascribed to free rotation CO 2 − radicals and used as a dosimetric one. The response to γ-ray doses ranging from 5 to 10 3 Gy and the thermal stability has been studied. The number of free radicals per 100 eV (G-value) was found to be 0.45 ± 0.1 and 0.9 ± 0.18 for coral and alanine, respectively. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 8 × 10 5 ± 1.6 × 10 5 years, and 1.12 eV, respectively.

Reactivity of a Fungal Laccase Towards Lignin in Softwood Kraft Pulp

SummaryThe reactivity of a fungal laccase to lignin of six different spruce kraft pulps with kappa numbers ranging from 15 to 110 was studied. Enzymatic oxidation of lignin was investigated by monitoring the oxygen consumption in a suspension of the pulp and the number of radicals generated in the pulp, as measured by electron paramagnetic resonance spectroscopy. The laccase catalyzed oxidation of lignin in kraft pulp followed a double exponential function. This indicates the presence of two types of substrates oxidized by the enzyme at different rates. The two substrates were interpreted as lignin located on the surface of the pulp fibers and as lignin in the cell wall. A linear relationship was found between the kappa number of the pulps and the observed first-order rate constant for oxidation of substrate in the cell wall. Quantification of free radicals in the pulp showed a linear dependence on the lignin content and the number of free radicals generated upon oxidation with laccase.