Biomedical subjects

J M Monserrat

Publications and source records attributed to J M Monserrat.

At least 19 recordsLinked to original sources

PubMed1999

Inhibitory effects of cadmium on carbonic anhydrase activity and ionic regulation of the estuarine crab Chasmagnathus granulata (Decapoda, Grapsidae).

This work was aimed at evaluating the gill carbonic anhydrase (CA) activity of the estuarine crab Chasmagnathus granulata exposed in vivo to cadmium, at different salinities. The in vivo effect of the specific inhibitor acetazolamide (AZ) was also assayed. Besides, the inhibition of CA activity by different heavy metals (cadmium, copper, zinc) and AZ were evaluated under in vitro conditions. For the in vivo assays, adult males were acclimated to salinities of 2.5 or 30/1000. The corresponding 96-h LC50 of cadmium was 2.69 mg l-1 at 2.5/1000, and > 50 mg l-1 at 30/1000. Cadmium only caused a significant lower CA activity than control at 2.5/1000. EC50 for CA inhibition was estimated to be 1.59 mg l-1 at 2.5/1000. Statistical differences in Na+ hemolymphatic levels (P < 0.05) were only detected at 2.5/1000, between 0 and 1.25 mg l-1 of cadmium, but no statistical differences were observed for Cl- levels at any assayed salinity. As CA inhibition registered at 2.5/1000 was followed by only changes in Na+ concentration, it is likely that cadmium exposure could differentially affect ions permeability, among others factors. The concentrations that inhibited in vitro 50% of enzymatic activity (IC50) were 2.15 x 10(-5), 1.62 x 10(-5), 3.75 x 10(-6) and 4.4 x 10(-10) M for cadmium, copper, zinc and AZ, respectively. The comparison with IC50 values of other aquatic species, indicates a higher CA sensitivity for C. granulata to pollutants.

Acclimatization↗

PubMed1998

Some kinetic and toxicological characteristics of thoracic ganglia cholinesterase of Chasmagnathus granulata (Decapoda, Grapsidae).

In this study, some kinetic and toxicological parameters of the thoracic ganglia cholinesterase from the estuarine crab Chasmagnathus granulata were determined. Effects of the type and concentration of substrate, pH (6.80-8.50), incubation temperature (5-35 degrees C) and eserine on the enzyme activity were studied. Enzymatic activity was higher at pH 7.40 and 8.00 and significantly reduced at lower temperatures (5-10 degrees C). Employing acetylthiocholine iodide (ATCh) as substrate, the K(m) and Vmax were estimated as 0.28 mM and 1.75 mumol.mg protein-1.min-1, respectively. A 14.11 and 24.51% decrease in enzyme activity were registered at 4.62 and 9.24 mM of ATCh, respectively. Using propionylthiocholine iodide as substrate, the K(m) and Vmax were estimated as 0.16 mM and 0.91 mumol.mg protein-1.min-1, respectively. The IC50 for eserine was estimated as 5.3 x 10(-4) mM. The Ki estimated for eserine (8.10 mM-1.min-1) indicates that the thoracic ganglia cholinesterase from C. granulata showed a low ability to generate an irreversible enzyme-inhibitor complex. The higher enzymatic activity registered with ATCh and the enzyme inhibition observed at high concentration of this substrate, suggest that thoracic ganglia cholinesterase from C. granulata is an acetylcholinesterase.

Acetylthiocholine↗

PubMed1992

Chronic toxicity of ethyl parathion and isobutoxyethanol ester of 2,4-dichlorophenoxyacetic acid to estuarine juvenile and adult crabs.

The chronic toxicity of ethyl parathion and isobutoxyethanol ester of 2,4-dichlorophenoxyacetic acid was determined for the crabs Uca uruguayensis and Chasmagnathus granulata collected in Argentina in 1989. Parathion toxicity was more time-dependent than 2,4-D. Four-week LC50 values for parathion were size and species independent, as expected under chronic exposure conditions. As shown in previous studies, the opposite was noted when crabs were exposed to acute exposure. Parathion was much more toxic than 2,4-D, in all cases. Also, parathion exerted a very much lower chronic lethal effect than other pesticides at a fraction of the respective acute LC50. A different susceptibility between sexes was found in C. granulata exposed to 2,4-D.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1991

Effects of salinity on the toxicity of parathion to the estuarine crab Chasmagnathus granulata (Decapoda, Grapsidae).

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Animals↗

PubMed1991

Acute and chronic effects of parathion and 2,4 D on the oxygen consumption of Chasmagnathus granulata (Decapoda, Brachyura).

The effect of two pesticides widely used in Argentina on the oxygen consumption of the estuarine crab Chasmagnathus granulata was studied. Constant pressure respirometers were employed to estimate the rate of oxygen consumption per weight unit of animals treated previously with each pesticide, both acute (96 h) and chronically (15 and 30 days). Crabs exposed to parathion -an organophosphorate insecticide that causes the inhibition of acetylcholinesterase- show an increase of oxygen consumption at 0.5 ppm under acute exposure, and at 10 ppb under a chronic one. On the other hand, crabs exposed to 2,4 D (an herbicide) did not show changes in their consumption after an acute exposure, but those exposed chronically did show an increase at low concentration (5 ppm) followed by a relative decrease at the highest concentration (50 ppm). The results obtained for parathion are in accordance with the abnormal cholinergic excitation that it may exert on crustacean nervous system. The effect of 2,4 D was consistent with its uncoupler action at respiratory chain level, at low concentrations, while a possible Krebs cycle enzymes inhibition might be occurring at higher concentrations of that pesticide, as in other crustacean species. The faster action of parathion, respect to 2,4 D, is explained by its neurotoxic nature.

2,4-Dichlorophenoxyacetic Acid↗

PubMed1980

[Contribution to the diagnosis of Dubin-Johnson syndrome].

Eight patients with Dubin-Johnson's syndrome have been reported. It appoints the greatest casuistry about the theme in our country. The coincidence covers all the aspects of the disease except by the fact that we emphasize, as a matter of interest, that we were able to visualize the gallblader and the biliary tract through oral cholecystography visualize the gallblader and the biliary tract through oral cholecystography or through intravenous cholangiography, in all the patients who have been studied. It doesn't agree with the class descriptions in which these exams have negative results. So we point out the possibility of this disease's existence in spite of the radiographic visulaization of biliary tract, particularly in those patients with moderated hepatic pigment-deposit. Refering to pathologic anathomy we remark the importance in the search of the pigment charactiristic of the Dublin-Johnson's syndrome in all the liver histopathologic exams. Besides, we consider it valuable to make the Fontana-Masson coloration in those patients who present negative pigment reaction to iron. The systematic examinations of the cytoplasmatic pigments will allow us to diagnose the disease even in the cases with minimum and latent characteristics.

Adolescent↗

PubMed1969