1,720,968 research outputs found
Clinical research on the hepatotoxicity of toluene
No full textToluene is metabolized by the liver, and previous research gave contrasting results regarding toluene hepatotoxicity: the present clinical investigation was performed to study the effect of this solvent on hepatic function. 47 subjects exposed to toluene inhalation during working activity were studied. The workers were subjected to medical control and the following tests were performed: bilirubin, GOT, GPT, AP, OCT, GGT, Quick time and protein measurement. Standardized methods were used. All tests gave normal results, with the only exception of GGT, which was above normal (28 mU/ml) in 34% of the cases. In the group of subjects (12) controlled before and after toluene entered in the working operation, mean GGT activity resulted twofold after exposure, without any modification of other tests. These results suggest, in the light of preceding research, that the hepatic damage eventually caused by toluene is mediated through an effect on hepatic microsomal enzymes induction
Esposizione a toluene e danno epatico in addetti alla rotocalcografia.
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Heating reactivation of rats aminolevulinic acid dehydratase in lead poisoning.
Full text linkHeat reactivation (60 degrees C for 5 minutes) of the red blood cells aminolevulinic acid dehydratase activity was studied in lead treated rats (0.25 to 5.0 mg/kg b.w., i.p., for 4 weeks). Complete enzyme reactivation occurs with lead blood concentration up to about 70 mcg/dl. At higher blood lead concentrations, only a part of the enzyme can be restored by heating. The different mechanisms of aminolevulinic acid dehydratase activity inhibition by lead are discussed
Esposizione aimipramina e a toluene nell'industria farmaceutica. Osservazioni sul rischio di interazione tossica a livello epatico.
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Liver toxicity due to 1,2-dichloropropane in the rat.
Full text linkThe effect of 1,2-dichloropropane on rat liver was studied after short (5 days) and long term (4 weeks) i.p. administration. Animals were injected daily with 10-500 mg/kg body wt 1,2-dichloropropane and biochemical and histological changes of liver were investigated. Treatment was monitored by measuring urinary mercapturic acid excretion. A significant increase of mercapturate excretion was observed at all dose levels, with no further increase during the treatment; at lower doses a return to baseline values occurred within 48 h after the end of treatment. Mercapturate excretion at the end of weeks 2, 3 and 4 of treatment was significantly lower than that observed at the end of week 1. The liver reduced glutathione content was different after single or repeated injections. A dose-dependent decrease of liver reduced glutathione was observed after a single injection and a dose-dependent increase after 4 weeks. The liver biochemical pattern after 4 weeks of treatment (characterized by a decrease of cytochrome P-450 and by an increase of reduced glutathione and glutathione S-transferase activity) suggests a hyperplastic evolution of the liver cells, probably a repair mechanism induced by early depletion of reduced glutathione. Light microscopy confirms that the prevalent alterations are regenerative in type (atypical mitosis and hyperplastic nodules). Areas of focal necrosis are isolated, and trend to disappear after long term treatment
In vivo interaction of lead with aminolevulinic acid dehydratase and induction of a thermolabile factor: an experimental model.
No full textAminolevulinic acid dehydratase (ALA-D) activity of male albino Wistar rats was used as an experimental model for a study on the interaction of lead with biological systems. Lead at 1 mg/kg was administered i.p. and the rats were killed immediately, and at 30 min, 1, 2, 3, and 4 h after treatment. It was shown that lead (Pb) interacted directly with the enzyme molecule immediately after treatment, first on the active site of zinc (Zn) and then on the thiolic groups. Induction of the so-called thermolabile factor (TF) seemed to occur later, i.e., it may only be shown from the 2nd-3rd h after treatment. The long-term persistence of lead-induced TF in the acute phase of intoxication may be the key to the interpretation of some chronic toxic effects
1-Chloro-2-hydroxypropane epoxidase in rat liver and other organs
No full text1,2-Dichloropropane, a widely used solvent for paint and varnish, is metabolized by the rat liver microsomal system to give a hydroxyl metabolite which is then epoxidized. The present study reports on a method for determining 1-chloro-2-hydroxypropane epoxidase and its distribution in several organs in rats. 10000xg supernatants from 20% w/v homogenates (0.1 ml) were incubated with 0.3 ml of a cofactor mixture (0.08 μmol NADP, 1.5 μmol glucose-6-phosphate, 7.8 μmol niacinamide and 3.9 μmol MgCl2 in phosphate buffer 0.1 M, pH 7.4) and 0.1 ml of substrate (0.01 M). After incubation for 30 min at 37°C, formation of propylene glycol was measured according to Harger & Forney. Enzyme activities (nmol-1 mg protein-1, mean±SD) were as follows: liver 2.84±0.61; kidney cortex 8.50±1.22; testis 8.41±2.19; lung 4.61±1.15. These results support our previous report that the solvent has a greater toxic effect on the kidney. This may be due to the higher epoxide formation during the metabolism of the solvent
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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