Overexpression of manganese-superoxide dismutase prevents methylmercury toxicity in HeLa cells

HeLa cells were stably transformed with plasmid constructs that allowed constitutive expression of antioxidant enzymes such as catalase, glutathione peroxidase (GSH-Px), Cu,Zn-superoxide dismutase (Cu,Zn-SOD) or Mn-superoxide dismutase (Mn-SOD) to examine the involvement of reactive oxygen generation in methylmercury toxicity. Overexpression of catalase, GSH-Px or Cu,Zn-SOD did not affect the sensitivity of HeLa cells against methylmercury. However, the sensitivity of HeLa cells against methylmercury was decreased by overexpression of Mn-SOD, an enzyme localized in matrix of mitochondria and which decomposes superoxide anions. These results suggest that formation of superoxide anions in the mitochondria might be involved in the mechanism of the cytotoxicity of methylmercury.     

Expression of superoxide dismutase following axotomy

Genomic clones for a chitinolytic enzyme were isolated from a library of Sau 3A digested DNA from the tobacco hornworm, Manduca sexta, using a previously isolated chitinase cDNA clone as a probe [Kramer et al., Insect Biochem. Molec. Biol. 23, 691-701 (1993)]. Restriction enzyme mapping and Southern blot analysis of four genomic clones suggested that these are overlapping clones. Sequence analysis of the genomic clones and Southern blot analysis of total genomic DNA also suggest that the M. sexta genome has only one chitinase gene detectable by the cDNA probe. This gene is organized into at least 11 exons in a region spanning > 11 kb. The sequenced M. sexta chitinase gene has a series of exons corresponding to identifiable structural/functional regions of the protein. Similarities in structure and organization between the M. sexta chitinase gene and chitinase genes from other sources are described.     

Comparative antioxidant and cardioprotective effects of ceruloplasmin, superoxide dismutase and albumin

The antioxidant effects of ceruloplasmin (CAS 9031-37-2) against oxygen free radicals (.O2-, .OH, 1O2) and their by-products (H2O2, HOCl), generated by electrolysis of Krebs-Henseleit buffer, were determined in vitro by the DPD (N,N-diethyl-p-phenylenediamine) colorimetric method and ex vivo by quantifying cardiodynamic variables of the isolated perfused rat heart. Purified ceruloplasmin (1 mumol/l) displayed a high antioxidant capacity in vitro (89.2%), while the scavenging capacity of superoxide dismutase (SOD) in equimolar concentrations was 38.1%. A relatively high scavenging activity (72.1%) was observed with bovine serum albumin (BSA). A control group of Langendorff isolated rat hearts (n = 8) was submitted to electrolysis (10 mA, for 1 min) without treatment, whereas the treated groups were perfused with ceruloplasmin, SOD or BSA (1 mumol/l) in the inflow cannula for 5 min before, during, and 5 min after electrolysis. The cardioprotective effect afforded by ceruloplasmin (83-89%) was higher than that observed with the same optimal dose of 1 mumol/l SOD (20-45%). With BSA, no protection was observed ex vivo. Particularities in scavenging specificities and mechanisms seem to explain the important differences between in vitro and ex vivo antioxidant capacities for these proteins.     

Suppression of mouse-killing in rats following irradiation

Suppression of mouse-killing was produced following pairings of mouse-presentations (CS) with 96 roentgens of ionizing radiation (US) at O ( less than 2 min.) and 30 min. US-CS interstimulus intervals. No suppression was found at CS-US intervals of 30 min., 1hr., and 2 hr., or at US-CS intervals of 1 hr. and 2 hr.     

Activities of conjugating and antioxidant enzymes following endotoxin exposure

Endotoxin exposure elicits various responses in mammals including the acute phase response that has been shown to cause changes in the activity of several forms of cytochrome P450s and other enzymes. Therefore, the hepatic conjugating enzyme, glutathione S-transferase (GST), and UDP-glucuronosyltransferase (UDPGT), the antioxidant enzymes, glutathione peroxidase (GSHPx), catalase, and superoxide dismutase (SOD), as well as lipid peroxidation were investigated following the administration of endotoxin to male Sprague-Dawley rats (8 mg/kg body weight). Rats were euthanized at various times following endotoxin administration and the livers removed and processed to assess various enzyme activities. Glutathione S-transferase, UDPGT, and GSHPx activity showed statistically significant decreases after 24 hours and remained lower than controls for the duration of the study. Decreases in total SOD and catalase activities were seen at 24, 48, and 72 hours following endotoxin administration; however, only catalase activity showed statistically significant differences between control and treated samples at those time points, and total SOD activity showed a statistically significant decrease at 24 hours. No statistically significant changes were seen in the level of lipid peroxidation in the liver microsomes from endotoxin-treated animals. Changes in the conjugative enzymes and the free-radical scavenging enzymes following endotoxin exposure may alter the host's metabolism and response to free radicals.     

Chronic UVA (365-nm) irradiation induced scratching in hairless mice: dose-time dependency and the effect of ketanserin

In a study on the dose-response relationship for longwave UVA (UVA1; 340-400 nm) carcinogenesis in hairless mice scratch marks appeared after months of daily exposure as an unwanted side effect. Tumor induction in the highest of the 4 tested dose groups (receiving a daily dose of 430 kJ/m2 of 365-nm radiation) could not be determined because extensive scarification occurred prior to the development of any tumors. The induction of scratch marks could be scored and quantified in all 4 dose groups tested. The UVA1 dose-dependencies for the induction of tumors and scratch marks were compared. We found that the induction of scratch marks depended mainly on the cumulative UVA1 exposure, whereas tumor induction showed a lesser dose-dependency. An attempt was made to prevent the apparent pruritogenic effect of UVA1 irradiation and to understand its mechanism. The influence of ketanserin, a serotonin/histamine antagonist, on the UVA1 induction of scratch marks was tested in groups of 8 mice daily irradiated with 430 kJ/m2. No difference was found between treated and untreated animals. Histological examination of skin biopsies from irradiated mice from the 430-kJ/m2 dose group from the UVA1 carcinogenic experiment, showed no changes in numbers of mast cells or other inflammatory features when compared to skin biopsies from unirradiated control mice. This indicated that UVA1-induced scratching is not mediated through mast cell release of serotonin and/or histamine. An adequate therapeutic treatment which can prevent UVA1-induced scratching would enable us to test tumor induction with UVA1 over a larger dose range, and may provide additional insight in how this radiation damages the skin. It remains conjectural whether there exists an analogous UVA-induced pruritus in human skin.     

Protective effect of RibCys following high-dose irradiation of the rectosigmoid

Ribose-cysteine (RibCys) is a prodrug of L-cysteine that stimulates glutathione biosynthesis. Increased glutathione levels have been shown to have a protective effect against radiation-induced injury and oxidative stress. Surface oximetry has previously been used successfully to predict anastomotic leakage. PURPOSE: The following study was done to evaluate the protective effect of RibCys and the predictive value of PtO2 determinations in a swine model. METHODS: Domestic swine were divided into three groups: Group A served as a nonradiated control; Group B received 6,000 to 6,500 rad to the rectosigmoid; and Group C received RibCys (1 g/kg) prior to receiving 6,000 to 6,500 rad. Radiated animals and controls underwent rectosigmoid resection after a three-week rest period. Intraoperative anastomotic PtO2 was checked with a modified Clark electrode. Anastomoses were evaluated radiographically at three and seven days; animals were sacrificed, and bursting strength was recorded at 10 days. RESULTS: Mean bursting pressures were 243.8 +/- 59.4, 199.5 +/- 37.8, and 209.5 +/- 54.9 mmHg (NS) for Groups A, B, and C, respectively. Anastomotic PtO2 ranged from 19 to 98 mmHg and could not be correlated with anastomotic leaks or bursting pressure. There were 11/15 radiation-related deaths and leaks (eight deaths and three leaks) in the radiated group and 4/12 radiation-related deaths and leaks (three deaths and one leak) in the group receiving radiation and RibCys (P < 0.04). CONCLUSIONS: 1) RibCys protected animals against radiation-related deaths and anastomotic leaks following high doses of pelvic irradiation; 2) anastomotic PtO2 levels did not correlate with anastomotic healing in this model.     

Absence of hemoprotein-associated free radical events following oxidant challenge of crosslinked hemoglobin-superoxide dismutase catalase

Crosslinking hemoglobin with superoxide dismutase and catalase (PolyHb-SOD-CAT) helps to limit free radical reactivity of modified hemoglobin red blood cell substitutes. In the present study, in vitro oxidant challenge experiments were performed with exogenous hydrogen peroxide (H2O2) and xanthine oxidase-derived superoxide (O2.-). PolyHb-SOD-CAT was compared to PolyHb for the presence of secondary hemoprotein-free radical events. PolyHb-SOD-CAT prevents ferrylhemoglobin formation, measured as Na2S-induced absorbance at 620 nm. Similarly, PolyHb-SOD-CAT inhibited ferrozine-detectable iron release at high oxidant-heme ratios. The formation of oxygen radicals, monitored by salicylate hydroxylation, was prevented at high oxidant-heme ratios with PolyHb-SOD-CAT. The peroxidation of liposomal membranes was also inhibited in PolyHb-SOD-CAT mixtures subject to oxidant challenge. These results show that PolyHb-SOD-CAT prevents secondary hemoprotein-associated free radical events. This new type of modified hemoglobin oxygen carrier with antioxidant activity may reduce the potential toxicity of hemoglobin-based substitutes in certain applications, especially during reperfusion of ischemic tissues.     

Superoxide dismutase and total antioxidant status of larvae and adults of Trichostrongylus colubriformis, Haemonchus contortus and Ostertagia circumcincta

By means of modern color-coded duplex sonography (CCDS) even very small vessels can be visualized. Maximum resolution nowadays is about 0.5 mm diameter of the vessel. We compared the use of CCDS and angiography in studying of acral perfusion. Besides morphologic criteria, hemodynamic criteria were recorded. Arteries in healthy fingers appear as long and straight vessels with a clearly defined border. The physiological maximal blood flow velocity exceeded 20 cm/s. CCDS revealed tortuosity of finger arteries as typical finding in thrombangiitis obliterans. Segmental stenosis can either be identified morphologically or quantified by measurement of the flow velocity with poststenotic maximal systolic velocities of less than 20 cm/s or by the acceleration of the blood flow within the stenosis, as proven by angiographic examinations. CCDS is suitable for evaluation of acral perfusion in patients suffering from secondary Raynaud's syndrome. Apart from diagnosis of disturbed acral circulation, other possible applications of CCDS are in in the surgical field, for example replantations in hand or finger surgery.     

Physical and biological predictors of changes in whole-lung function following thoracic irradiation

PURPOSE: To develop methods of predicting the pulmonary consequences of thoracic irradiation (RT) by prospectively studying changes in pulmonary function following RT. METHODS AND MATERIALS: 100 patients receiving incidental partial-lung irradiation during treatment of tumors in or adjacent to the thorax had whole-lung function assessed via symptoms and pulmonary function tests (PFTs: FEV1-forced expiratory volume 1 s; DLCO-diffusion capacity) before and repeatedly 6-48 months following RT. All had computed tomography-based three-dimensional (3D) dose calculations with lung density heterogeneity corrections for dose-volume histogram (DVH) and normal tissue complication probability (NTCP) calculations. Functional DVHs (DVfH) based on SPECT (single photon emission computed tomography) lung perfusion scans, and serial transforming growth factor-beta (TGF-beta1) levels were available in 50 and 48 patients, respectively. The incidence and severity of changes in whole-lung function were correlated with clinical, physical, and biological factors. Exploratory statistical analyses were performed using chi-square, Pearson correlations, logistic regression, and multiple linear regression. RESULTS: RT-induced symptoms developed in 21 patients. In the overall group, the single best predictor for the development of symptoms was the NTCP (p < 0.05). Pre-RT PFTs alone were less predictive (p = 0.1 for FEV1, p = 0.08 for DLCO). A multivariate model based on pre-RT DLCO and CT-based NTCP was strongly predictive for the development of symptoms (p < 0.001). NTCPs based on SPECT-derived DVf Hs and TGF-beta1 levels did not appear to provide additional predictive value. The presence or absence of pulmonary symptoms was correlated with the decline in PFT 6 months following RT (p < 0.05). In the overall group, the degree of decline in PFTs was not well correlated with any of the dose-volume variables considered. In patients with "good" pre-RT PFTs, there was a relationship between the percent reduction in PFT and dose-volume parameters such as the percent of lung volume receiving > 30 Gy (p < 0.05). CONCLUSION: The extent of alteration in whole-lung function (symptoms or PFT changes) appears to be related to both dose-volume and pre-RT PFT parameters. The data suggest that no one variable is likely to be an adequate predictor and that multivariate predictive models will be needed. Additional studies are underway to develop better predictive models that consider physical factors such as the DVH and regional perfusion, as well as biological/clinical factors such as pre-RT PFTs and TGF-beta1.     

The effect of sodium nucleinate on the precursors of antigen-dependent suppressors following irradiation

Sodium nucleinate was administered perorally to mice in the dose of 30 mg/kg. After the treatment the suppression activity of spleen cells decreased. The decrease was more pronounced in mice exposed to the doses of 0.5 and 1 Gy than in intact mice. The dose of 240 mg/kg did not affect suppression activity.     

Extinction of an avoidance response following response prevention: Some parametric investigations.

Conducted 2 experiments to investigate parameters influencing the efficacy of response prevention. In Exp. I, with 44 female hooded rats, the amount of response prevention given to Ss who had learned to avoid electric shock in an automated apparatus was systematically varied. Increasing the duration of response prevention increased its effectiveness in hastening extinction. In Exp. II, with 31 Ss, the intensity of shock used in avoidance learning was parametrically varied. More intense shock diminished the efficacy of a fixed amount of response prevention. In both experiments, S's spontaneous behavior during response prevention was systematically recorded. The cessation of fear behavior and the occurrence of relaxation during response prevention were found to predict accurately the successful extinction of the avoidance response. (French summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Induction of proinflammatory cytokine and antioxidant enzyme gene expression following brief myocardial ischaemia

PURPOSE: In a recent study we found an increased resistive index immediately after extracorporeal shock wave lithotripsy (ESWL) in patients older than 60 years, which suggests renovascular disturbance. The present 26-month followup study was undertaken to investigate the relevance of elevated resistive index levels and the incidence of new onset hypertension. MATERIALS AND METHODS: Of the initial 76 patients 57, including 20 of the 23 at risk patients 60 or greater years, group 3), were followed for more than 26 +/- 6 months after ESWL. Followup included 2 resistive index measurements by Doppler ultrasound of the treated and the contralateral kidney, at least 2 blood pressure measurements 1 week apart and excretory urography as well as determination of plasma renin activity in 9 patients. RESULTS: With 1 exception, elevated resistive index levels and hypertension were observed exclusively in patients older than 60 years. In these patients the resistive index ranged between 0.65 and 0.86 (mean plus or minus standard deviation 0.74 +/- 0.05, normal less than 0.7). This increase in resistive index was statistically significant (p < 0.0001). Compared to the levels obtained immediately after ESWL, the resistive index continued to increase in all 9 patients older than 60 years who had hypertension (45%), whereas in the normotensive patients the resistive index was either stable or decreased. There was a strong positive correlation (0.903) between pathological resistive index levels and blood pressure. CONCLUSIONS: Patients older than 60 years are at risk for disturbances of renal perfusion as assessed by the resistive index, and 45% of these patients have new onset hypertension within 26 months of treatment.