Antioxidant response and oxidative stress levels in Macrobrachium borellii (Crustacea: Palaemonidae) exposed to the water-soluble fraction of petroleum.

The aim of the present work was to evaluate the effect of the water soluble fraction of hydrocarbons (WSF) on the antioxidant status of the freshwater prawn Macrobrachium borellii. First, seasonal variations were studied in a non-polluted area. Hepatopancreas and gills showed season-related fluctuations in catalase (CAT), glutathione-S-transferase (GST) activities and in lipid peroxidation levels (LPO), but not in superoxide dismutase (SOD). Then, adults were exposed semi-statically to sublethal doses for 7days. CAT, SOD, GST, and glutathione peroxidase (GPx) activities and LPO, reduced glutathione (GSH) and protein oxidation (PO) levels were determined. Exposed individuals showed significant increases in CAT, SOD, and GST activities in hepatopancreas and CAT activity in gills. GPx activity did not vary in either tissues. While LPO levels increased, GSH levels decreased significantly in hepatopancreas of exposed animals, but PO levels showed no variation. Induction of SOD was also assessed by Real-time PCR mRNA expression in hepatopancreas. The non-enzymatic antioxidant activity was also tested; ABTS 2,2'-azino-bis(3-ethyl-benzothiazoline-6-sulfonic acid) was higher in hemolymph of treated-prawns compared to controls, but ferric reducing activity of plasma assay (FRAP) values did not change. Taken together, the present results indicated that the antioxidant defenses of M. borellii, mainly in hepatopancreas, were significantly affected by aquatic hydrocarbon contamination, regardless of the season.

Antioxidant activity of Paraguayan plant extracts.

The antioxidant properties of six medical herbs used in the traditional Paraguayan medicine were studied using free radical-generating systems. The methanol extracts from Aristolochia giberti, Cecropia pachystachya, Eugenia uniflora, Piper fulvescens, Schinus weinmannifolia and Schinus terebinthifolia protected against enzymatic and non-enzymatic lipid peroxidation in microsomal membranes of rat. C. pachystachya, E. uniflora, S. weinmannifolia and S. terebinthifolia showed the highest scavenging activity on the superoxide and DPPH radicals.

Inhibition of Trypanosoma cruzi growth by medical plant extracts.

This study describes the screening of extracts obtained from 18 plants and two fungi used in the Chinese and Mediterranean traditional medicines on epimastigote forms of Trypanosoma cruzi. The extracts were tested against epimastigote of T. cruzi Bra C15C2 clone in vitro at 27 degrees C and at a concentration of 250 microg/ml in axenic culture. Angelica dahurica, A. pubescens, A. sinensis, Astragalus membranaceus, Coptis chinensis, Haplophyllum hispanicum, Phellodendron amurense, Poria cocos, Ranunculus sceleratus and Scutellaria baicalensis showed significant effects against the parasite with a percentage of growth inhibition between 20 and 100%. C. chinensis and R. sceleratus showed the greatest activity with IC(50) values of 1.7 microg/ml for C. chinensis and 10.7 microg/ml for R. sceleratus. These activities are greater than that of allopurinol. C. chinesis and R. sceleratus extracts did not show cytotoxic effects on rat polimorphonuclear cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and lactic dehydrogenase assays. These results allowed us to suggest that R. sceleratus and C. chinensis could be a source of new compounds clinically active against T. cruzi.

Antioxidant activity of anti-inflammatory plant extracts.

The antioxidant properties of twenty medical herbs used in the traditional Mediterranean and Chinese medicine were studied. Extracts from Forsythia suspensa, Helichrysum italicum, Scrophularia auriculata, Inula viscosa, Coptis chinensis, Poria cocos and Scutellaria baicalensis had previously shown anti-inflammatory activity in different experimental models. Using free radical-generating systems H. italicum. I. viscosa and F. suspensa protected against enzymatic and non-enzymatic lipid peroxidation in model membranes and also showed scavenging property on the superoxide radical. All extracts were assayed at a concentration of 100 microg/ml. Most of the extracts were weak scavengers of the hydroxyl radical and C. chinensis and P. cocos exhibited the highest scavenging activity. Although S. baicalensis inhibited the lipid peroxidation in rat liver microsomes and red blood cells, the extract showed inhibitory actions on aminopyrine N-demethylase and xanthine oxidase activities as well as an pro-oxidant effect observed in the Fe3+-EDTA-H2O2 system. The results of the present work suggest that the anti-inflammatory activities of the same extracts could be explained, at least in part, by their antioxidant properties.

MR perfusion imaging using encapsulated laser-polarized 3He.

In this work, the use of a new carrier agent for intravascular laser-polarized 3He imaging is reported. Lipid-based helium microbubbles were investigated. Their average diameter of 3 microm, which is smaller than that of the capillaries, makes it possible to conduct in vivo studies. The NMR relaxation parameters T1, T2, and T2* of a microbubble suspension were measured as 90 s, 300 ms, and 4.5 ms, respectively, and in vivo images of encapsulated 3He with signal-to-noise ratios (SNRs) larger than 30 were acquired. Dynamic cardiac images and vascular images of encapsulated 3He were obtained in rats using intravenous injections of microbubble suspensions. Excellent preservation of 3He polarization through the lung capillaries and heart cavities was observed. The first images of 3He microbubble distributions in the lungs were obtained. Additionally, the potential of this technique for lung perfusion assessment was validated through an experimental embolism model with the visualization of perfusion defects.

Mixed micelles containing lipophilic gadolinium complexes as MRA contrast agents.

Mixed micelles for MRA are multicomponent systems containing a phospholipid, a biocompatible non-ionic surfactant (e.g. Synperonic(R) F-108) and a lipophilic gadolinium complex. A variety of lipophilic gadolinium complexes were designed taking into account features such as: (i) nature of ligand (cyclic versus acyclic); (ii) lipophilic moiety; (iii) global charge of the complex; and (iv) nature of bond connecting the complex to the lipophilic moiety. All the lipophilic gadolinium complexes after formulation as mixed micelles show high relaxivities in water and in blood (rat). Mixed micelles containing gadolinium complexes bearing only one aliphatic chain cannot be used as MRA contrast agents because they have a high haemolytic effect. Furthermore, in rats they are quickly eliminated from the blood stream. These drawbacks are completely circumvented using gadolinium complexes bearing two aliphatic chains. Mixed micelles containing such complexes show high relaxivities, no haemolytic effect and long blood permanence. This makes them promising candidates as MRA contrast agents. However, elimination, which occurs exclusively through the liver, is not complete, even after 7 days. Complexes containing labile (e.g. ester) bonds between the lipophilic moieties and the chelate subunit are eliminated through both the liver and the kidneys. However, elimination is still not complete after 7 days.

Vascular and perfusion imaging using encapsulated laser-polarized helium.

In this work, the use of hyperpolarized (HP) 3He for in vivo intravascular imaging on animal is reported. To overcome the problem of the low solubility of helium in blood, we propose an approach based on helium encapsulation in lipid-based carrier agents. The mean diameter of the 3He microbubbles, measured equal to 3.0+/-0.2 microm, makes it possible to conduct in vivo studies. In vitro spectroscopy yielded a longitudinal relaxation time T(1) equal to 90 s and an apparent transverse relaxation time T(2)(*) of 4.5 ms. Angiographic imaging (venous and cardiac cavity visualization), as well as lung perfusion imaging, were demonstrated in rats using intravenous injections of microbubble suspensions. Suitable signal and spatial resolution were achieved. The potential of this technique for lung perfusion assessment was assessed using an experimental animal embolism model. Lung perfusion defects and recovery towards a normal perfusion state were visualized. This study was completed with the demonstration of a new ventilation-perfusion lung exploration method based entirely on HP 3He.

Detection of experimental hepatic tumors using long circulating superparamagnetic particles.

RATIONALE AND OBJECTIVES: To evaluate the potential of an iron oxide-based MR contrast agent for the detection and delineation of experimental liver tumors during the early vascular phase of the compound. METHODS: Superparamagnetic blood pool agent (SBPA) was administered intravenously to rabbits bearing VX2 tumors. Images were acquired before the injection, immediately after, and 1 or 3 weeks later. The variations of signal intensity were measured in the tumors and in several tissues for various T1-weighted spin-echo, T2-weighted fast spin-echo, and T2-weighted gradient-recalled-echo sequences. RESULTS: Fourteen and 12 of the 16 tumors were detected immediately after SBPA injection using, respectively, the T2-weighted fast spin-echo and T2-weighted gradient-recalled-echo sequences. A significant decrease in signal intensity was observed in well-perfused organs, and blood signal was abolished even at the lowest injected dose and using a T1-weighted sequence. In the late phase, the loss in signal intensity of the liver was even more pronounced. CONCLUSION: The dominant T2 effect of SBPA induces an increase in the tumor-to-liver and tumor-to-blood contrast during the vascular phase, improving the detection of the tumors and allowing the distinction between small lesions and vessels through plane. This effect on the liver signal persists for several days because of the incorporation of SBPA in the reticuloendothelial system.

Is the protection against ischemia induced by red wine linked to its antioxidant capacity?

OBJECTIVE: To establish whether the total antioxidant capacity of nonalcoholic extracts of three Argentine red wines (RWE) is correlated with their protection against ischemia-reperfusion injury. ANIMALS AND METHODS: The antioxidant properties of three RWE were determined using different free radical-generating systems. To examine the effects of these RWE during a 20 min global ischemic period followed by 30 min of reperfusion, isolated rat hearts received 50 mug/mL of RWE 1 (cabernet-sauvignon), RWE 2 (malbec) or RWE 3 (a commercial mixture of cabernet-sauvignon, malbec and merlot) 10 min before and after ischemia. Left ventricular developed pressure (LVDP), maximal velocity of rise of left ventricular pressure (+dP/dt(max)) and left ventricular end-diastolic pressure (LVEDP) were used to assess contractility and diastolic function. RESULTS: All RWE inhibited lipid peroxidation induced by the Cl(4)C/NADPH system in a similar proportion (42+/-4%, 47+/-9% and 43+/-14% for RWE 1, RWE 2 and RWE 3, respectively). The scavenging activity of superoxide anion and 2,2-diphenyl-1-picryl-hydrazyl radical was about the same with the three RWE. In hearts without RWE treatment, LVDP and +dP/dt(max) were 61+/-4% and 62+/-5%, respectively, at the end of the reperfusion period. Infusion of RWE 1 and RWE 2 significantly improved postischemic recovery (LVDP and +dP/dt(max) were 102+/-4% and 101+/-4% for RWE 1 and 92+/-5% and 91+/-5% for RWE 2, respectively) and attenuated the increase of LVEDP. RWE 3 did not improve either systolic or diastolic dysfunction. CONCLUSION: These data show that although the three non-alcoholic RWE exhibit a similar total antioxidant capacity, only two of them protect the heart against myocardial stunning, suggesting that the protective effect is not primarily linked to the anti-oxidant properties of the extracts.

[Trypanosoma cruzi: obtaining extracellular amastigotes and studying their development under different culture conditions]. / Trypanosoma cruzi: obtención de amastigotes extracelulares y estudio de su crecimiento en diferentes condiciones de cultivo.

This work describes a protocol to obtain pure populations of extracellular amastigotes of Trypanosoma cruzi. The amastigote stage was obtained by means of temperature changes and human plasma added to the culture medium. Epimastigotes (clon BraC15C2) were first grown in F69 medium at 27 degrees C during 96 h and then at 36.5 degrees C. After three subcultures of 96 h each at the latter temperature a subsequent incubation in the presence of 5% human plasma, was needed to obtain a population of amastigotes that could be maintained indefinitely in the F69 or F29 media. This amastigote population was similar morphologically to that obtained through other methods. The kinetic of growth depended on the culture medium used (F29 or Brain-Heart Infusion, BHI). When culture was incubated at 27 degrees C in both media, the pre-exponential and logarithmic phases of growth were observed at 72-96 h and 24-48 h respectively. The change in stage from amastigote to epimastigote dependent whether amastigote were subcultured or not. The growth of amastigotes in BHI medium at 36.5 degrees C did not occurred. The growth of amastigotes was similar to those observed at 27 degrees C when F29 medium was used although the transformation to epimastigotes did not take place at this temperature. A population over 99% of amastigotes were maintained at 36.5 degrees C indefinitely by means of subcultures in F29 medium.

Antioxidant effects of an aqueous extract of Ilex paraguariensis.

In this work we investigate the antioxidant properties of an aqueous extract prepared from an infusion of Ilex paraguariensis (Aquifoliaceae) using free radical-generating systems. The extract inhibited the enzymatic and nonenzymatic lipid peroxidation in rat liver microsomes in a concentration-dependent fashion, with IC(50) values of 18 microg/ml and 28 microg/ml, respectively. The extract also inhibited the H(2)O(2)-induced peroxidation of red blood cell membranes with an IC(50) of 100 microg/ml and exhibited radical scavenging properties toward superoxide anion (IC(50) = 15 microg/ml) and 2,2-diphenyl-1-picrylhydrazyl radical. In the range of concentrations used, the extract was not a scavenger of the hydroxyl radical. Our results suggest that ingestion of extracts of Ilex paraguariensis could contribute to increase the antioxidant defense of an organism against free radicals attack.

Extracellular ABTS-oxidizing activity of autochthonous fungal strains from Argentina in solid medium.

The screening for extracellular oxidases and peroxidases from autochthonous filamentous fungi isolated from different substrates is an important step towards the detection of extracellular fungal oxidative systems. Thirty-one autochthonous fungal strains from Argentina, belonging to different ecophysiological and taxonomic groups, were plate-screened for their ability to produce extracellular oxidoreductases. Modified Kirk solid medium containing the chromogen 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) was used to determine the presence of this extracellular activity. The fungi tested were grouped according to the colour intensity of the modified Kirk medium in: a) species without extracellular ABTS-oxidizing activity; b) species with low extracellular ABTS-oxidizing activity; c) species with moderate extracellular ABTS-oxidizing activity; d) species with high extracellular ABTS-oxidizing activity. The assay revealed extracellular ABTS-oxidizing activity in 90% of the strains tested. All species of Basidiomycetes used exhibited ABTS-oxidizing activity, except Laeticorticium roseum. Aspergillus terreus and Epicoccum purpurascens (Deuteromycetes) did not show extracellular oxidative activity on ABTS. Agrocybe aegerita, Amauroderma boleticeum, Cladosporium cladosporioides, Coriolopsis rigida, Grammothele subargentea, Graphium putredinis, Hexagona hydnoides, Hexagona papyraceae, Loweporus lividus, Peniophora albobadia, Phellinus everhartii, Phellinus gilvus; Phellinus linteus; Pleurotus laciniatocrenatus, Pycnoporus sanguineus, Rigidoporus ulmarius, Steccherinum rawakense, Talaromyces helicus, Trametes elegans, Trametes pavonia, Trametes villosa and Trichaptum sector are reported here for the first time as species capable of producing ABTS-oxidizing extracellular oxidorreductases.

Effect of the chloroform extract of Tanacetum vulgare and one of its active principles, parthenolide, on experimental gastric ulcer in rats.

This study examines the anti-ulcerogenic activity of a chloroform extract of Tanacetum vulgare and purified parthenolide, the major sesquiterpene lactone found in the extract. Gastric ulcers induced by oral administration of absolute ethanol to rats were reduced dose-dependently by oral pretreatment of animals with the chloroform extract (2.5-80 mg kg(-1)) or parthenolide (5-40 mg kg(-1)). When administered 30 min before challenge with the alcohol the protection ranged between 34 and 100% for the extract and 27 and 100% for parthenolide. When the products were administered orally 24 h before treatment with ethanol, 40 mg kg(-1) of the extract and of the lactone reduced the mean ulcer index from 4.8+/-0.3 for control animals to 1.4+/-0.2 and 0.5+/-0.1, respectively. The products also prevented alcohol-induced reduction of the number of sulphydryl groups within the gastric mucosa (50.6+/-2.3 microg (mgprotein)(-1) for normal animals compared with 17.7+/-3.0 microg (mg protein)(-1) for alcohol-treated animals). Administration of the extract (80 mg kg(-1)) or parthenolide (40 mg kg(-1)) 24 h before ethanol treatment restored the numbers of mucosal -SH groups to values near those found for normal animals. These results suggest that the products assayed, in particular parthenolide, might find therapeutic application, although further work is required to establish their profit/risk ratio.

Long circulating superparamagnetic particles with high T2 relaxivity.

Novel superparamagnetic particles coated with a phospholipid and a surfactant were characterized and evaluated in vivo. These particles (SBPA) were shown to exhibit r2 relaxivities in the range of 350-450 mM-1.s-1, r1 values of 8-12 mM-1.s-1 and sizes of 50-80 nm. Preliminary results of pharmacokinetics were obtained in rats following the administration of 59Fe-labelled preparations. The particles were shown to remain for hours in the blood stream before being cleared mainly by the liver. Most of 59Fe was eliminated from the body and recovered in the feces within a week. These biodistribution and elimination properties deserve more detailed studies and suggest the potential use of this product as a blood pool contrast agent.

Effect of arsenic (V) on the antioxidant defense system: in vitro oxidation of rat plasma lipoprotein.

Adult male rats were treated orally with sodium arsenate (10 mg As/kd/day) for 2 days, and in increase in hepatic glutathione level was seen. Ascorbic acid content increased in both liver and plasma of intoxicated animals. Hepatic activities of superoxide dismutase and glutathione peroxidase did not change with the treatment and there was no increase in the level of lipid peroxidation measured as thiobarbituric acid-reacting substances (TBARS). Arsenic decreased the plasma level of uric acid and increased the plasma triglycerides content without modifying vitamin E levels. Both total lipoproteins and very low density lipoprotein plus low density lipoprotein (VLDL + LDL) fractions demonstrated greater propensity for in vitro oxidation than the corresponding untreated rats. The last finding might be a useful parameter for determining the degree of oxidative stress in the initial steps of intoxication with arsenic.

Effects of lovastatin on the fatty acid desaturation in a human lung mucoepidermoid carcinoma grown in nude mice.

The effect of lovastatin, a hypocholesterolemic drug, on tumor growth and desaturase activity was studied in a human lung mucoepidermoid carcinoma (HLMC) grown in nude mice. After administration of a diet supplemented with 25 mg% (w/w) lovastatin for 30 days the growth of HLMC was not inhibited. Liver and tumor phospholipid/cholesterol ratio was increased in lovastatin group but serum cholesterol was unaffected. Treatment with lovastatin increased delta 5 and delta 9 desaturation in tumor microsomes, whereas delta 6 desaturation did not change in tumors of treated mice. The changes were not reflected in the fatty acid composition of total tumor lipids.

Enhancement of computed tomography liver contrast using iomeprol-containing liposomes and detection of small liver tumors in rats.

RATIONALE AND OBJECTIVES: We evaluated iomeprol-containing liposomes (Lipiom), a new contrast medium for computed tomography (CT) liver scanning, in an animal model of chemically induced hepatocellular carcinomas and other liver tumors in rats. METHODS: Liver tumors were induced by administration of carcinogens to rats, either 0.55% (w/w) 1'-hydroxysafrole in the diet or induction by 3'-methyl-4-diethylaminoazobenzene followed by promotion with carbon tetrachloride. CT scanning was performed 1-3 hr after intravenous injection of iomeprol-containing liposomes. RESULTS: After injection of iomeprol-containing liposomes at a dose of 70 mg of liposome-entrapped iodine per kilogram of body weight, the normal liver parenchyma showed a contrast enhancement, in Hounsfield units, of more than 60% over the control value before bolus. Liver tumors with no or few Kupffer cells were not enhanced and appeared as dark areas within the normal parenchyma. Tumors and pretumoral lesions devoid of Kupffer cells, as small as 3 mm in diameter, could be distinguished using this non-invasive method. CONCLUSION: CT liver scanning after injection of iomeprol-containing liposomes appears to be promising method for detecting liver tumors and focal liver lesions.

[Trypanosoma cruzi: influence of human plasma on the morphogenesis of blood trypomastigotes in a cell-free culture media]. / Trypanosoma cruzi: influencia del plasma humano en la morfogénesis de tripomastigotes sanguíneos en un medio de cultivo acelular.

Morphogenesis of blood stream trypomastigotes in the cell free culture medium F69 at 37 degrees C for 10 days showed qualitative differences either with or without human plasma. Without human plasma, blood stream trypomastigotes performed only one cycle before disappearing and the culture kept growing as amastigotes and epimastigotes until the end of the experiment. In contrast, human plasma induced multiple cycles of transformation. The sequence was blood stream trypomastigotes, regressive parasites, amastigotes, progressive parasite and again trypomastigotes. Human plasma preserved the trypomastigote stage, produced a blockade of the epimastigote stage and inhibited the division of amastigotes. In this experimental model, human plasma modified the biological cycle of T. cruzi by inducing or inhibiting different stages.