The importance of an efficient extraction protocol for the use of fish muscle cholinesterases as biomarkers.

Esterase activity found in muscle extracts is useful to evaluate harmful effects of anticholinesterase pollutants. Yet, most procedures applied in the extraction of fish muscle esterases in order to investigate their activity as a biomarker of environmental exposure comprise the homogenization of muscle tissue in low-salt solutions, followed by centrifugation to separate the supernatant as the enzyme source. However, acetylcholinesterase (AChE), the main target in these monitoring efforts, is a membrane-bound protein and is only present in muscle extracts if homogenization is carried out using chaotropic high-salt solutions.

Bioconcentration and Acute Intoxication of Brazilian Freshwater Fishes by the Methyl Parathion Organophosphate Pesticide.

Three species of freshwater Brazilian fishes (pacu, Piaractus mesopotamicus; piavussu, Leporinus macrocephalus, and curimbatá, Prochilodus lineatus) were exposed to an acute dose of 5 ppm methyl parathion organophosphate pesticide. Three to five individuals per species were exposed, one at a time, to 40 liters tap water spiked with Folidol 600. Pesticide concentrations and cholinesterase (ChE) activities were evaluated in serum, liver, brain, heart, and muscle.

Cholinesterase activity of muscle tissue from freshwater fishes: characterization and sensitivity analysis to the organophosphate methyl-paraoxon.

The biochemical characterization of cholinesterases (ChE) from different teleost species has been a critical step in ensuring the proper use of ChE activity levels as biomarkers in environmental monitoring programs. In the present study, ChE from Oreochromis niloticus, Piaractus mesopotamicus, Leporinus macrocephalus, and Prochilodus lineatus was biochemically characterized by specific substrates and inhibitors. Moreover, muscle tissue ChE sensitivity to the organophosphate pesticide methyl-paraoxon was evaluated by determining the inhibition kinetic constants for its progressive irreversible inhibition by methyl-paraoxon as well as the 50% inhibitory concentration (IC50) for 30 min for each species.

Flavonoids and other compounds from Ouratea ferruginea (Ochnaceae) as anticancer and chemopreventive agents.

The chemical study of the extracts from leaves and stems of Ouratea ferruginea allowed the identification of a new isoflavone, 5-hydroxy-7,3'4'5'-tetramethoxyisoflavone, and twenty two known compounds, including friedelin, 3β-friedelinol, lupeone, a mixture of sitosterol, stigmasterol and campesterol, sitosteryl- and stigmasteryl-3-O-b-D-glucopyranosides, 5,4'-dihydroxy-7,5',3'-trimethoxyisoflavone, 5,4'-dihydroxy-7,3'-di-methoxyisoflavone (7,3'-di-O-methylorobol), 5,7,4'-trihydroxy-3',5'-dimethoxyisoflavone (piscigenin), 2R,3R-epicatechin, syringic acid, 2,6-dimethoxybenzoquinone, 2,6-dimethoxyhydroquinone, syringic and ferulic aldehyde, a mixture of vanillic acid, 1-hydroxy-2-methoxy-4-(1E-3-hydroxy-1-propenyl)-benzene and 3,5-dimethoxy-4-hydroxy-dihydrocinamaldehyde, besides amenthoflavone and 7-O-methylamenthoflavone (sequoiaflavone) which are considered as chemotaxonomic markers of Ouratea. The structures were identified by IR, (1)H- and (13)C-NMR and GC-MS, HPLC-MS, besides comparison with literature data. The inhibitory effects of 5,4'-dihydroxy-7,5',3'-trimethoxyisoflavone, 7,3'-di-O-methylorobol, piscigenin and 7-O-methylamenthoflavone on cytochrome P450-dependent 7-ethoxycoumarin O-deethylase (ECOD) and glutathione S-transferase (GST) were evaluated in vitro.

Cardiac alterations in furosemide-treated thiamine-deprived rats.

Background: Chronic administration of furosemide may induce thiamine deficiency and cause or aggravate myocardial dysfunction.

Methods And Results: Wistar rats were divided into four groups according to food and treatment: (1) thiamine standard chow with intraperitoneal furosemide administration; (2) thiamine standard chow with intraperitoneal saline administration; (3) thiamine-deficient chow with intraperitoneal furosemide administration; and (4) thiamine-deficient chow with intraperitoneal saline administration. Thiamine status was evaluated by high-performance liquid chromatography determination in plasma, erythrocytes, and myocardium, and by erythrocyte transketolase activity and the thiamine pyrophosphate effect to recover transketolase activity.

Cytosolic glutathione peroxidase from liver of pacu (Piaractus mesopotamicus), a hypoxia-tolerant fish of the Pantanal.

Pacu (Piaractus mesopotamicus Holmberg, 1887, Characiformes) dwells in waters of Pantanal, in which it has adapted for alternate concentrations of dissolved oxygen. Intracellular antioxidant protection should be vital for such an adaptation. Accordingly, we found that cytosol from liver of pacu has the highest antioxidant glutathione peroxidase activity so far reported for fish and murine species.

A novel butyrylcholinesterase from serum of Leporinus macrocephalus, a Neotropical fish.

We show here that serum of piaussu, a Neotropical characin fish, has the highest butyrylcholinesterase activity so far described for humans and fish. To clarify whether this cholinesterase could protect piaussu against anticholinesterase pesticides by scavenging organophosphates, we purified it 1700-fold, with a yield of 80%. Augmenting concentrations (from 0.

Methyl-paraoxon comparative inhibition kinetics for acetylcholinesterases from brain of neotropical fishes.

Acetylcholinesterase (AChE) sensitivity to the organophosphorus (OP) pesticide methyl-paraoxon was measured in fourteen species of Neotropical marine and freshwater fish found in the waters of Brazil. The rate constant for phosphorylation, kp, the dissociation constant, kd, the second order rate constant, ki, and the IC50 value were measured at 28 degrees C in pH 7.5 buffer for AChE extracted from brain.

Pseudomonas aeruginosa-induced production of free radicals by IFNgamma plus TNFalpha-activated human endothelial cells: mechanism of host defense or of bacterial pathogenesis?

We have previously shown that human umbilical vein endothelial cells (HUVEC) can be activated by IFNgamma plus TNFalpha to kill intracellular (IC) Pseudomonas aeruginosa through production of reactive oxygen intermediate, but the cumulative effects of cytokine activation and bacterial infection on host cells has not been extensively addressed. In this study we investigated the fate of IFNgamma plus TNFalpha-activated HUVEC that have harboured IC bacteria for up to 24 h. At 10 h, the endothelial cell killing of P.

Cross-modal generalization of habituation in the rat.

Novel stimuli were presented in a runway where rats run for food. Subjects in a pre-exposure condition (n = 6) were exposed to visual and auditory stimulation and then to an olfactory stimulus; subjects not preexposed (n = 6) only received the olfactory stimulus. Reaction to the odor was lower in pre-exposed subjects.