The effect of computed tomography on oxidative stress level and some antioxidant parameters.

BACKGROUND: X-rays are defined as ionizing radiation and hydrolyze the water, causing free radical formation. Oxidative stress is the damage that occurs in cells due to the lack of antioxidants, which detoxifies them, with the increased production of free radicals that occur during normal cellular metabolism. PURPOSE: To examine the acute effects of computed tomography (CT), i.e. ionizing radiation, on oxidative stress and antioxidant defense mechanisms. MATERIAL AND METHODS: The study included a total of 53 patients that were selected among the patients that underwent non-contrast full-body CT. Malondialdehyde (MDA) and reduced glutathione (GSH) levels and superoxide dismutase (SOD) and catalase (CAT) activities were investigated in blood samples taken from patients. RESULTS: The post-scan levels of MDA increased significantly while the post-scan levels of GSH, SOD, and CAT decreased significantly compared to their pre-scan levels. CONCLUSION: CT, which is a widely used X-ray imaging technique and has numerous known side effects, was found to increase the levels of MDA, which is an indicator of oxidative stress, and to decrease the levels of some antioxidants including GSH, SOD, and CAT.

Molecular and Biochemical Basis of Fluoroquinolones-Induced Phototoxicity-The Study of Antioxidant System in Human Melanocytes Exposed to UV-A Radiation.

Phototoxicity of fluoroquinolones is connected with oxidative stress induction. Lomefloxacin (8-halogenated derivative) is considered the most phototoxic fluoroquinolone and moxifloxacin (8-methoxy derivative) the least. Melanin pigment may protect cells from oxidative damage. On the other hand, fluoroquinolone-melanin binding may lead to accumulation of drugs and increase their toxicity to skin. The study aimed to examine the antioxidant defense system status in normal melanocytes treated with lomefloxacin and moxifloxacin and exposed to UV-A radiation. The obtained results demonstrated that UV-A radiation enhanced only the lomefloxacin-induced cytotoxic effect in tested cells. It was found that fluoroquinolones alone and with UV-A radiation decreased superoxide dismutase (SOD) activity and SOD1 expression. UV-A radiation enhanced the impact of moxifloxacin on hydrogen peroxide-scavenging enzymes. In turn, lomefloxacin alone increased the activity and the expression of catalase (CAT) and glutathione peroxidase (GPx), whereas UV-A radiation significantly modified the effects of drugs on these enzymes. Taken together, both analyzed fluoroquinolones induced oxidative stress in melanocytes, however, the molecular and biochemical studies indicated the miscellaneous mechanisms for the tested drugs. The variability in phototoxic potential between lomefloxacin and moxifloxacin may result from different effects on the antioxidant enzymes.

Neuroprotective efficacy of luteolin on a 900-MHz electromagnetic field-induced cerebellar alteration in adult male rat.

The adverse health consequences of exposure to electromagnetic field emitted from cell phone has recently raised public concerns worldwide. Also, the Global System for Mobile Communications (GSM) standard that operates in 900 MHz frequency is the most popular. Therefore, we aimed to investigate the adverse effect of exposure to 900 MHz EMF (1 h/day) on the cerebella of 12-week-old rats. We also evaluated the protective activity of luteolin (20 µg/kg/day) against possible biological change in the cerebellar tissues exposed to EMF. Twenty-four male wistar albino rats were randomly assigned into four group of six rats: Control, EMF, EMF + luteolin, luteolin. Serological and biochemical analyses, as well as histopathological examination were performed on all cerebellar samples. We found that SOD (superoxide dismutase) level was significantly increased in the EMF group compared to the control group (p < 0.05). To the contrary, decreased SOD activity was detected in the EMF + luteolin group compared to control group (p < 0.05). The total number of Purkinje and granular cells was significantly decreased in the EMF group compared to the control group (p < 0.05). In the EMF + luteolin group, the total number of Purkinje and granular cells was significantly higher than the EMF group (p < 0.05). Histopathological evaluation also showed destructive damage to the architectures of cerebellar tissues. Our results suggest that exposure to EMF may cause cellular damage to the rat cerebellum. Further, the improvement of cerebellar damage may have resulted from antioxidant efficacy of luteolin by alleviating oxidative stress.

Effect of ultrasonic field on the enzyme activities and ion balance of potential pathogen Saccharomyces cerevisiae.

OBJECTIVES: This study aimed at investigating the enzyme activities and ion concentrations in potential pathogen S.cerevisiae upon ultrasonic treatment. METHODS: The activities of ATPase and antioxidase were identified by ATPase, SOD, and CAT assay kits following the instructions. Extracellular Ca2+ and K+ concentrations were determined in an atomic absorption spectrometer with calcium and potassium hollow-cathode lamps as radiation sources. RESULTS: SOD and CAT activities were enhanced by relatively low ultrasonic power at early time points and reduced to lower levels. Total ATPase, Na+/K+-ATPase, and Ca2+/Mg2+-ATPase activities were reduced by ultrasonic field, with higher reducing rate at stronger ultrasonic power and early time points. In addition, ultrasonic field disturbed the Ca2+ and K+ balances in S.cerevisiae cells. CONCLUSIONS: Ultrasonic field resulted in the reduce even the lost of S.cerevisiae cell viability.

Comparison of the trapping effect and antioxidant enzymatic activities using three different light sources in cockchafers.

Light traps have been widely used for controlling underground pests. However, very little is known regarding the relationship between trapping effect and antioxidant enzymatic activities using light irradiation in underground pests. Thus, we determined the trapping effect of three light sources of the frequoscillation pest-killing lamp on two species of cockchafers, Serica orientalis Motschulsky (Coleoptera: Melolonthidae) and Anomala corpulenta Motschulsky (Coleoptera: Rutelidae), and evaluated the effect of the same three light sources on the activities of their antioxidant enzymes. The catches of S. orientalis were significantly higher compared to A. corpulenta using light source A in peanut fields in China. After irradiation by light source A, the malondialdehyde (MDA) contents and activities of superoxide dismutase (SOD) and glutathione S-transferases (GST) in S. orientalis were significantly and marginally significantly lower compared to A. corpulenta. Taken together, these results indicated a weaker antioxidant enzyme activity response to light stress and a larger quantity of trapping catches using light irradiation in cockchafers. Thus, we proposed a potential negative relationship between trapping effect and antioxidant enzymatic activities in response to light irradiation in cockchafers.

[Study of the influence of low-dose γ-irradiation on the functional state of peripheral blood erythrocytes of rats].

Low-intensity radiation at the absorbed dose of 4 µGy/min is a stressor of medium strength. In male Wistar rats, a pronounced and long-lasting response occurs in the system of red blood cells at the accumulated dose of 4.8 mGy. Functional deficiency of circulating cells was evaluated by the resistance of erythrocytes to acid lyse and the activity of the main antioxidant enzymes--superoxide dismutase (SOD) and catalase (CAT). The minimum "threshold" doses of radiation that cause systemic reactions occur in the range of units of miligrey.

[The antioxidant enzyme activity in mouse liver mitochondria after nanosecond pulsed periodic X-ray exposure].

The effect of repetitive pulsed X-ray (4 ns pulse duration, 300 kV accelerating voltage; 2.5 kA electron beam current) on the antioxidant enzyme activity in mouse liver mitochondria has been investigated. The mitochondrial suspension was exposed to single 4000 pulse X-ray radiation with repetition rates ranging between 10 and 22 pps (pulsed dose was 0.3-1.8 x 10(-6) Gy/pulse, the total absorbed dose following a single exposure was 7.2 x 10(-3) Gy). It was shown that a short-time exposure to X-ray radiation changes the antioxidant enzyme activity in mouse liver mitochondria. The greatest effect was observed in the changes of the activity of the metal-containing enzymes: superoxide dismutase and glutathione peroxidase. The effect depends on the pulse repetition frequency and radiation dose.

Activation of de novo GSH synthesis pathway in mouse spleen after long term low-dose γ-ray irradiation.

Glutathione (GSH) is an important cellular antioxidant and has a critical role in maintaining the balance of cellular redox. In this study, we investigated the GSH biosynthesis genes involved in the elevation of endogenous GSH levels using an irradiation system with an irradiation dose rate of 1.78 mGy/h, which was about 40,000 times less than the dose rates used in other studies. The results showed that GSH levels were significantly increased in the low-dose (0.02 and 0.2 Gy) irradiated group compared to those in the non-irradiated group, but enzymatic antioxidants such as superoxide dismutase and catalase were not induced at any doses tested. The elevation in GSH was accompanied by elevated expression of glutamate-cysteine ligase modifier subunit, but no changes were observed in the expression of glutamate-cysteine ligase catalytic subunit and thioredoxin in de novo GSH synthesis. In the case of genes involved in the GSH regeneration cycle, the expression of glutathione reductase was not changed after irradiation, whereas glutathione peroxidase was only increased in the 0.2 Gy irradiated group. Collectively, our results suggest that the de novo pathway, rather than the regeneration cycle, may be mainly switched on in response to stimulation with long-term low-dose radiation in the spleen.

Effect of UV radiation on a thermostable superoxide dismutase purified from a thermophilic bacterium isolated from a sterilization drying oven.

A thermostable superoxide dismutase from a thermophilic bacterium, called Geobacillus wiegeli (GWE1), isolated from the interior of a sterilization drying oven, was purified by anion-exchange and molecular size-exclusion liquid chromatography. On the basis of SDS-PAGE, the purified enzyme was found to be homogeneous and showed an estimated subunit molecular mass of 23.9 kDa. The holoenzyme is a homotetramer of 97.3 kDa. Superoxide dismutase exhibited maximal activity at pH 8.5 and at temperature around 60 ºC. The enzyme was thermostable maintaining 50% of its activity even after 4.5 hours incubation at 60 ºC and more than 70% of its activity after 30 min at 80 ºC. When the microorganism was irradiated with UVA, an increase in the specific activity of superoxide dismutase was observed which was correlated with decreasing levels of anion superoxide, indicating the direct involvement of this enzyme in the capture of reactive oxygen species. This study reports the effects of UV radiation on a superoxide dismutase from a thermophilic bacterium isolated from an anthropogenic environment.

Pre-treatment of seeds with static magnetic field ameliorates soil water stress in seedlings of maize (Zea mays L.).

The effect of magnetic field (MF) treatments of maize (Zea mays L.) var. Ganga Safed 2 seeds on the growth, leaf water status, photosynthesis and antioxidant enzyme system under soil water stress was investigated under greenhouse conditions. The seeds were exposed to static MFs of 100 and 200 mT for 2 and 1 h, respectively. The treated seeds were sown in sand beds for seven days and transplanted in pots that were maintained at -0.03, -0.2 and -0.4 MPa soil water potentials under greenhouse conditions. MF exposure of seeds significantly enhanced all growth parameters, compared to the control seedlings. The significant increase in root parameters in seedlings from magnetically-exposed seeds resulted in maintenance of better leaf water status in terms of increase in leaf water potential, turgor potential and relative water content. Photosynthesis, stomatal conductance and chlorophyll content increased in plants from treated seeds, compared to control under irrigated and mild stress condition. Leaves from plants of magnetically-treated seeds showed decreased levels of hydrogen peroxide and antioxidant defense system enzymes (peroxidases, catalase and superoxide dismutase) under moisture stress conditions, when compared with untreated controls. Mild stress of -0.2 MPa induced a stimulating effect on functional root parameters, especially in 200 mT treated seedlings which can be exploited profitably for rain fed conditions. Our results suggested that MF treatment (100 mT for 2 h and 200 for 1 h) of maize seeds enhanced the seedling growth, leaf water status, photosynthesis rate and lowered the antioxidant defense system of seedlings under soil water stress. Thus, pre sowing static magnetic field treatment of seeds can be effectively used for improving growth under water stress.

MnSOD expression inhibited by electromagnetic pulse radiation in the rat testis.

Male Sprague Dawley rats were exposed to EMP irradiation of 100 kV/m peak-to-peak e-field intensity and different numbers of pulses. Rat sperm samples were prepared for analysis of sperm qualities; Testes were assessed by transmission electron microscopy and serum hormone concentrations were examined by radioimmunoassay; Enzymatic activities of Total-superoxide dismutase(T-SOD) and manganese-superoxide dismutase (MnSOD), the mRNA levels of MnSOD and cuprozinc-superoxide dismutase (CuZnSOD), and the density of malondialdehyde (MDA) were also determined. EMP irradiation did not affect spermatozoon morphology, micronucleus formation rate, sperm number or viability, but the acrosin reaction rate decreased at 24 h and 48 h and recovered by 72 h after irradiation as compared to the controls. The ultrastructure of rat testis displayed more serious damage at 24 h than at other time points (6 h, 12 h, 48 h). Serum levels of luteotrophic hormone (LH) and testosterone (T) were elevated in irradiated rats as compared to controls. After irradiation, enzymatic activities of T-SOD and MnSOD were reduced by 24 h, consistent with the changes observed in MnSOD mRNA expression; MDA content increased at 6 h in turn. These studies have quantified the morphological damage and dysfunction in the rat reproductive system induced by EMP. The mechanism of EMP induced damage may be associated with the inhibition of MnSOD expression.

900-MHz microwave radiation promotes oxidation in rat brain.

Recently, there have been several reports referring to detrimental effects due to radio frequency electromagnetic fields (RF-EMF) exposure. Special attention was given to investigate the effect of mobile phone exposure on the rat brain. Since the integrative mechanism of the entire body lies in the brain, it is suggestive to analyze its biochemical aspects. For this, 35-day old Wistar rats were exposed to a mobile phone for 2 h per day for a duration of 45 days where specific absorption rate (SAR) was 0.9 W/Kg. Animals were divided in two groups: sham exposed (n = 6) and exposed group (n = 6). Our observations indicate a significant decrease (P < 0.05) in the level of glutathione peroxidase, superoxide dismutase, and an increase in catalase activity. Moreover, protein kinase shows a significant decrease in exposed group (P < 0.05) of hippocampus and whole brain. Also, a significant decrease (P < 0.05) in the level of pineal melatonin and a significant increase (P < 0.05) in creatine kinase and caspase 3 was observed in exposed group of whole brain as compared with sham exposed. Finally, a significant increase in the level of ROS (reactive oxygen species) (P < 0.05) was also recorded. The study concludes that a reduction or an increase in antioxidative enzyme activities, protein kinase C, melatonin, caspase 3, and creatine kinase are related to overproduction of reactive oxygen species (ROS) in animals under mobile phone radiation exposure. Our findings on these biomarkers are clear indications of possible health implications.

Study of the response of superoxide dismutase in mouse organs to radon using a new large-scale facility for exposing small animals to radon.

We examined dose-dependent or dose rate-dependent changes of superoxide dismutase (SOD) activity using a new large-scale facility for exposing small animals to radon. Mice were exposed to radon at a concentration of 250, 500, 1000, 2000, or 4000 Bq/m(3) for 0.5, 1, 2, 4, or 8 days. When mice were exposed to radon at 2000 day•Bq/m(3), activation of SOD activities in plasma, liver, pancreas, heart, thymus, and kidney showed dose-rate effects. Our results also suggested that continuous exposure to radon increased SOD activity, but SOD activity transiently returned to normal levels at around 2 days. Moreover, we classified the organs into four groups (1. plasma, brain, lung; 2. heart, liver, pancreas, small intestine; 3. kidney, thymus; 4. stomach) based on changes in SOD activity. Thymus had the highest responsiveness and stomach had lowest. These data provide useful baseline measurements for future studies on radon effects.

Leaf extract of Moringa oleifera prevents ionizing radiation-induced oxidative stress in mice.

The present study evaluated the hepatoprotective effect of aqueous ethanolic Moringa oleifera leaf extract (MoLE) against radiation-induced oxidative stress, which is assessed in terms of inflammation and lipid peroxidation. Swiss albino mice were administered MoLE (300 mg/kg of body weight) for 15 consecutive days before exposing them to a single dose of 5 Gy of 6°Co γ-irradiation. Mice were sacrificed at 4 hours after irradiation. Liver was collected for immunoblotting and biochemical tests for the detection of markers of hepatic oxidative stress. Nuclear translocation of nuclear factor kappa B (NF-κB) and lipid peroxidation were augmented, whereas the superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH), and ferric reducing antioxidant power (FRAP) values were decreased by radiation exposure. Translocation of NF-κB from cytoplasm to nucleus and lipid peroxidation were found to be inhibited, whereas increases in SOD, CAT, GSH, and FRAP were observed in the mice treated with MoLE prior to irradiation. Therefore pretreatment with MoLE protected against γ-radiation-induced liver damage. The protection may be attributed to the free radical scavenging activity of MoLE, through which it can ameliorate radiation-induced oxidative stress.

Photoprotection by honeybush extracts, hesperidin and mangiferin against UVB-induced skin damage in SKH-1 mice.

The possible mechanism of photoprotection by polyphenolic extracts of honeybush and the two most abundant polyphenols found in honeybush, hesperidin and mangiferin were determined using a mouse model. Ethanol: acetone soluble extracts and pure honeybush compounds were applied topically to the skin of SKH-1 mice before daily exposures to ultraviolet B (UVB) (180 mJ/cm²) for 10 days. The honeybush extracts reduced signs of sunburn, such as erythema, peeling and hardening of the skin and also significantly (P < 0.05) reduced edema, epidermal hyperplasia and the induction of cyclooxygenase-2 (COX-2), ornithine decarboxylase (ODC), GADD45 and OGG1/2 expression. The fermented honeybush extract significantly (P < 0.05) reduced lipid peroxidation and depletion of the antioxidant enzymes catalase and superoxide dismutase. Hesperidin and mangiferin were less effective. These results show that extracts of honeybush and to some extent, hesperidin and mangiferin, renders protection against UVB-induced skin damage. The mechanisms investigated suggest that honeybush extracts protected the skin via modulation of induced-oxidative damage, inflammation and cell proliferation. Other specific biological properties such as modulation of signaling pathways could also be involved.

Modulation of NF-κB and FOXOs by baicalein attenuates the radiation-induced inflammatory process in mouse kidney.

The bioactive flavonoid baicalein has been shown to have radioprotective activity, although the molecular mechanism is poorly understood in vivo. C57BL/6 mice were irradiated with X-rays (15 Gy) with and without baicalein treatment (5 mg/kg/day). Irradiation groups showed an increase of NF-κB-mediated inflammatory factors with oxidative damage and showed inactivation of FOXO and its target genes, catalase and SOD. However, baicalein suppressed radiation-induced inflammatory response by negatively regulating NF-κB and up-regulating FOXO activation and catalase and SOD activities. Furthermore, baicalein inhibited radiation-induced phosphorylation of MAPKs and Akt, which are the upstream kinases of NF-κB and FOXOs. Based on these findings, it is concluded that baicalein has a radioprotective effect against NF-κB-mediated inflammatory response through MAPKs and the Akt pathway, which is accompanied by the protective effects on FOXO and its target genes, catalase and SOD. Thus, these findings provide new insights into the molecular mechanism underlying the radioprotective role of baicalein in mice.

SOD2-mediated effects induced by WR1065 and low-dose ionizing radiation on micronucleus formation in RKO human colon carcinoma cells.

RKO36 cells exposed to either WR1065 or 10 cGy X rays show elevated SOD2 gene expression and SOD2 enzymatic activity. Cells challenged at this time with 2 Gy exhibit enhanced radiation resistance. This phenomenon has been identified as a delayed radioprotective effect or an adaptive response when induced by thiols or low-dose radiation, respectively. In this study we investigated the relative effectiveness of both WR1065 and low-dose radiation in reducing the incidence of radiation-induced micronucleus formation in binucleated RKO36 human colon carcinoma cells. The role of SOD2 in this process was assessed by measuring changes in enzymatic activity as a function of the inducing agent used, the level of protection afforded, and the inhibitory effects of short interfering RNA (SOD2 siRNA). Both WR1065 and 10 cGy X rays effectively induced a greater than threefold elevation in SOD2 activity 24 h after exposure. Cells irradiated at this time with 2 Gy exhibited a significant resistance to micronucleus formation (P < 0.05; Student's two-tailed t test). This protective effect was significantly inhibited in cells transfected with SOD2 siRNA. SOD2 played an important role in the adaptive/delayed radioprotective response by inhibiting the initiation of a superoxide anion-induced ROS cascade leading to enhanced mitochondrial and nuclear damages.

[Effect of different light of LED light quality on growth and antioxidant enzyme activities of Ganoderma lucidum].

OBJECTIVE: To study the effect of light quality on growth, antioxidant enzyme activities of Ganoderma lucidum mycelium. METHOD: G. lucidum mycelium was cultured under different light qualities by light emitting diodes (LED). The growth G. lucidum mycelium was observed and antioxidant enzyme activities was determined in different growth periods. RESULT: Under the red LED, the blue LED and dark condition (CK), the mycelium grew faster than that under other light qualities. The white LED resulted in a largest increase in the amount of the mycelium and always kept the activities of CAT high level. Major fluctuations of POD activities emerged under the green LED, while enhanced severely in the late phase. Under the yellow LED, the activities of SOD appeared high level. However, SOD activities on dark (CK) raised obviously in late period. At the late stage, the content of mycelium polysaccharides was significant higher than that under the blue LED. CONCLUSION: The light quality could influence the growth and metabolism of G. lucidum mycelium.

Mutagenic response of 2.45 GHz radiation exposure on rat brain.

PURPOSE: To investigate the effect of 2.45 GHz microwave radiation on rat brain of male wistar strain. MATERIAL AND METHODS: Male rats of wistar strain (35 days old with 130 +/- 10 g body weight) were selected for this study. Animals were divided into two groups: Sham exposed and experimental. Animals were exposed for 2 h a day for 35 days to 2.45 GHz frequency at 0.34 mW/cm(2) power density. The whole body specific absorption rate (SAR) was estimated to be 0.11 W/Kg. Exposure took place in a ventilated Plexiglas cage and kept in anechoic chamber in a far field configuration from the horn antenna. After the completion of exposure period, rats were sacrificed and the whole brain tissue was dissected and used for study of double strand DNA (Deoxyribonucleic acid) breaks by micro gel electrophoresis and the statistical analysis was carried out using comet assay (IV-2 version software). Thereafter, antioxidant enzymes and histone kinase estimation was also performed. RESULTS: A significant increase was observed in comet head (P < 0.002), tail length (P < 0.0002) and in tail movement (P < 0.0001) in exposed brain cells. An analysis of antioxidant enzymes glutathione peroxidase (P < 0.005), and superoxide dismutase (P < 0.006) showed a decrease while an increase in catalase (P < 0.006) was observed. A significant decrease (P < 0.023) in histone kinase was also recorded in the exposed group as compared to the control (sham-exposed) ones. One-way analysis of variance (ANOVA) method was adopted for statistical analysis. CONCLUSION: The study concludes that the chronic exposure to these radiations may cause significant damage to brain, which may be an indication of possible tumour promotion (Behari and Paulraj 2007).

Pre-treatment with mild UV irradiation suppresses reproductive toxicity induced by subsequent cadmium exposure in nematodes.

In nematodes, 10 J/m(2)/min of UV irradiation induced a mild reproductive toxicity. Pre-treatment with UV irradiation at 10 J/m(2)/min suppressed the formation of reproductive defects, and activated a noticeable reduction of percentage of population with hsp-16.2::gfp expression, an obvious elevation of superoxide dismutase activities, and decrease of oxidative damage in 50 and 100 microM Cd exposed nematodes; however, pre-treatment with UV irradiation at 20 J/m(2)/min caused a significant decrease of brood sizes or increase of generation times in Cd-exposed nematodes. Pre-treatment with mild UV irradiation did not suppress the formation of reproductive defects in 150 microM Cd-exposed nematodes. Furthermore, the adaptive response to reproductive toxicity from Cd exposure was not observed in a reactive oxygen species sensitive mev-1(kn1) mutant. Therefore, pre-treatment with mild UV irradiation triggers the resistance to reproductive toxicity from Cd exposure by at least partially inducing adaptation to oxidative stress and through a mev-1-dependent pathway.