Efeito do acetato de chumbo associado ou não ao sulfato ferroso em cérebro de ratos: análise das enzimas antioxidantes / Effect of lead acetate with or without iron sulfate in brain of rats: Analysis of antioxidant enzymes

O chumbo (Pb) é um metal pesado, tóxico e está presente em diversos sistemas biológicos. Quando absorvido pelo organismo na forma iônica (Pb2+) atua em vários órgãos e sistemas, podendo ocasionar alterações graves no sistema nervoso central. Em adição, tem sido relatado que o íon ferroso (Fe2+) pode apresentar, entre outros, um efeito protetor na neurotoxicidade causada pelo Pb2+. Portanto, o objetivo deste estudo foi avaliar os marcadores de estresse oxidativo no cérebro de ratos expostos com acetato de chumbo (Pb(C2H3O2)2) associado ou não ao sulfato ferroso (FeSO4). Assim, 36 ratos machos (Rattus norvergicus) recém desmamados, divididos em 6 grupos (G), de 6 animais cada, foram expostos durante 6 semanas. No grupo controle (G1) os animais ingeriram água deionizada; G2 e G3 receberam 0,26 mM e G4 e G5 1,05 mM de acetato de chumbo, somado a isso G3 e G5 foram suplementados com 20 mg de sulfato ferroso/Kg peso corporal a cada 2 dias; e para G6 utilizou-se água deionizada e sulfato ferroso. O cérebro dos animais foi coletado para a análise da atividade enzimática de catalase (CAT), superóxido dismutase (SOD), glutationa peroxidase (GPx), a concentração de glutationa reduzida (GSH), lipoperoxidação (TBARS), hidroperóxido de lipídio (HL) e das substâncias antioxidantes totais (SAT) (técnicas ABTS e DPPH). A atividade das enzimas GPx e SOD nos grupos experimentais diminuiu em relação ao controle, assim como ocorreu com a concentração de GSH (p<0,05). Quanto às análises de HL e CAT, a primeira apresentou tendência de aumento na concentração dos grupos experimentais sem exposição concomitante, já a segunda demonstrou discreta inclinação de aumento na atividade em relação ao controle (p>0,05). A dosagem de SAT-ABTS mostrou aumento nos grupos expostos com 1,05 mM de acetato de chumbo. Em relação à SAT-DPPH houve diminuição nos grupos experimentais (p<0,05). De acordo com os resultados, as enzimas SOD e GPX e a GSH são...

Lead (Pb2+) is a toxic heavy metal, found in all stages of the inert environment and in several biological systems. When uptaken by the organism, acts on several organs and systems and may cause severe damage in Central Nervous System. In addition, it has been reported that iron (Fe2+) may present, a protective effect on neurotoxicity caused by Pb2+. Therefore, the aim of this study was to evaluate the markers of oxidative stress in the brain of rats exposed with lead acetate (Pb(C2H3O2)2) associated or not with ferrous sulfate (FeSO4). Thus, 36 rats weaning (Rattus norvegicus) were, divided into 6 groups (G) of six animals and were exposed for six weeks.In the control group (G1), the animals received deionized water; G2 and G3 received 0,26 mM, G4 and G5 1,05 mM of lead acetate; in addition to this G3 and G5 were supplemented with 20mg of ferrous sulfate/Kg body weight every 2 days; G6 received deionized water and ferrous sulfate were used. The animals' brains were collected for analysis of the enzymatic activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), the concentration of reduced glutathione (GSH), lipid peroxidation (TBARS), lipid hydroperoxide (LH) and total antioxidant substances (TAS) (ABTS and DPPH technics). The activity of the enzymes SOD and GPx in the experimental groups decrease compared to control, as well as the concentration of GSH (p<0.05). Concerning to the analysis of HL and CAT, the first tended to increase the concentration in experimental groups without concomitant exposure with FeSO4, while the second showed a slight tendency for increase in activity compared to control (p>0.05). The dosage of TAS-ABTS showed an increase in the groups exposed with 1,05 mM of lead acetate. Regarding the SAT- DPPH there was a decrease in the experimental groups (p <0.05). According to the results, the enzymes SOD and GPx and GSH were affected by lead acetate and exposure with ferrous...

Efeito do acetato de chumbo associado ou não ao sulfato ferroso em cérebro de ratos: análise das enzimas antioxidantes / Effect of lead acetate with or without iron sulfate in brain of rats: Analysis of antioxidant enzymes

O chumbo (Pb) é um metal pesado, tóxico e está presente em diversos sistemas biológicos. Quando absorvido pelo organismo na forma iônica (Pb2+) atua em vários órgãos e sistemas, podendo ocasionar alterações graves no sistema nervoso central. Em adição, tem sido relatado que o íon ferroso (Fe2+) pode apresentar, entre outros, um efeito protetor na neurotoxicidade causada pelo Pb2+. Portanto, o objetivo deste estudo foi avaliar os marcadores de estresse oxidativo no cérebro de ratos expostos com acetato de chumbo (Pb(C2H3O2)2) associado ou não ao sulfato ferroso (FeSO4). Assim, 36 ratos machos (Rattus norvergicus) recém desmamados, divididos em 6 grupos (G), de 6 animais cada, foram expostos durante 6 semanas. No grupo controle (G1) os animais ingeriram água deionizada; G2 e G3 receberam 0,26 mM e G4 e G5 1,05 mM de acetato de chumbo, somado a isso G3 e G5 foram suplementados com 20 mg de sulfato ferroso/Kg peso corporal a cada 2 dias; e para G6 utilizou-se água deionizada e sulfato ferroso. O cérebro dos animais foi coletado para a análise da atividade enzimática de catalase (CAT), superóxido dismutase (SOD), glutationa peroxidase (GPx), a concentração de glutationa reduzida (GSH), lipoperoxidação (TBARS), hidroperóxido de lipídio (HL) e das substâncias antioxidantes totais (SAT) (técnicas ABTS e DPPH). A atividade das enzimas GPx e SOD nos grupos experimentais diminuiu em relação ao controle, assim como ocorreu com a concentração de GSH (p<0,05). Quanto às análises de HL e CAT, a primeira apresentou tendência de aumento na concentração dos grupos experimentais sem exposição concomitante, já a segunda demonstrou discreta inclinação de aumento na atividade em relação ao controle (p>0,05). A dosagem de SAT-ABTS mostrou aumento nos grupos expostos com 1,05 mM de acetato de chumbo. Em relação à SAT-DPPH houve diminuição nos grupos experimentais (p<0,05). De acordo com os resultados, as enzimas SOD e GPX e a GSH são...

Lead (Pb2+) is a toxic heavy metal, found in all stages of the inert environment and in several biological systems. When uptaken by the organism, acts on several organs and systems and may cause severe damage in Central Nervous System. In addition, it has been reported that iron (Fe2+) may present, a protective effect on neurotoxicity caused by Pb2+. Therefore, the aim of this study was to evaluate the markers of oxidative stress in the brain of rats exposed with lead acetate (Pb(C2H3O2)2) associated or not with ferrous sulfate (FeSO4). Thus, 36 rats weaning (Rattus norvegicus) were, divided into 6 groups (G) of six animals and were exposed for six weeks.In the control group (G1), the animals received deionized water; G2 and G3 received 0,26 mM, G4 and G5 1,05 mM of lead acetate; in addition to this G3 and G5 were supplemented with 20mg of ferrous sulfate/Kg body weight every 2 days; G6 received deionized water and ferrous sulfate were used. The animals' brains were collected for analysis of the enzymatic activity of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), the concentration of reduced glutathione (GSH), lipid peroxidation (TBARS), lipid hydroperoxide (LH) and total antioxidant substances (TAS) (ABTS and DPPH technics). The activity of the enzymes SOD and GPx in the experimental groups decrease compared to control, as well as the concentration of GSH (p<0.05). Concerning to the analysis of HL and CAT, the first tended to increase the concentration in experimental groups without concomitant exposure with FeSO4, while the second showed a slight tendency for increase in activity compared to control (p>0.05). The dosage of TAS-ABTS showed an increase in the groups exposed with 1,05 mM of lead acetate. Regarding the SAT- DPPH there was a decrease in the experimental groups (p <0.05). According to the results, the enzymes SOD and GPx and GSH were affected by lead acetate and exposure with ferrous...

Geobacillus stearothermophilus LV cadA gene mediates resistance to cadmium, lead and zinc in zntA mutants of Salmonella entérica serovar Typhimurium

Salmonella entérica serovar Typhimurium cells expressing the cadA gene of Geobacillus stearothermophilus LV exhibit a hypersensitive phenotype to cadmium chloride. Deletion of the ORF STM3576 from the Salmonella genome resulted in cadmium, lead and zinc sensitivity, confirming that this ORF is a homologue of the zntA gene. The observed sensitivity was reverted upon expression of the G. stearothermophilus LV cadA gene. These results indicate that the cadA gene product is involved in Cd, Pb and Zn resistance as a classical P-type ATPase and strongly suggest that the observed hypersensitive phenotype to these metals can be related to the function of the host ·zntA gene product.

Effect of lead with vitamin E, C, or Spirulina on malondialdehyde, conjugated dienes and hydroperoxides in rats.

Lead (100 ppm) was given in doubly deionised water for 30 days to one group of rats. The other groups received lead along with exogenous antioxidants like vitamin E (50 IU/kg), vitamin C (800 mg/kg) or Spirulina (1500 mg/kg) in food for a similar period. Levels of lipid peroxidation products such as malondialdehyde, conjugated diene and hydroperoxide were measured in liver, lung and kidney of treated rats. In lead treated animals there was a significant increase in the levels of these lipid peroxidative products. Administration of exogenous antioxidants in the lead treated animals reduced the levels of malondialdehyde, conjugated diene and hydroperoxide. It indicated that vitamin E, vitamin C and Spirulina had significant (P < 0.001) antioxidant activity thereby protecting the animals from lead induced toxicity.

Antidepressant-like effect of lead in adult mice

It has been reported that lead can cause behavioral impairment by inhibiting the N-methyl-D-aspartate (NMDA) receptor complex. MK-801, a noncompetitive NMDA receptor antagonist, exhibits an antidepressant-like action in the forced swimming test. The purpose of the present study was to determine whether subacute lead exposure in adult male Swiss mice weighing 30-35 g causes an antidepressant-like action in a forced swimming test. Mice were injected intraperitoneally (ip) with 10 mg/kg lead acetate or saline daily for 7 consecutive days. Twenty-four hours after the last treatment, the saline and lead-treated mice received an injection of MK-801 (0.01 mg/kg, ip) or saline and were tested in forced swimming and in open-field tests. Immobility time was similarly reduced in the saline-MK-801, Pb-saline and Pb-MK-801 groups compared to the saline-saline group (mean + or - SEM; 197.3 + or - 18.5, 193.5 + or - 15.8, 191.3 + or - 12.3 and 264.0 + or - 14.4 s, respectively; N = 9). These data indicate that lead may exert its effect on the forced swimming test by directly or indirectly inhibiting the NMDA receptor complex. Lead treatment caused no deficit in memory of habituation and did not affect locomotor activity in an open-field (N = 14). However, mice that received MK-801 after lead exhibited a deficit in habituation (22 per cent reduction in rearing responses between session 3 and 1; N = 14) as compared to control (41 per cent reduction in rearing responses; N = 15), further suggesting that lead may have affected the NMDA receptor activity. Forced-swim immobility in a basin in two daily consecutive sessions was also significantly decreased by lead exposure (mean + or - SEM; day 1 = 10.6 + or - 3.2, day 2 = 19.6 + or - 3.6; N = 16) as compared to control (day 1 = 18.4 + or - 3.8, day 2 = 34.0 + or - 3.7; N = 17), whereas the number of crossings was not affected by lead treatment, further indicating a specific antidepressant-like action of lead.

Opiatergic participation in the thirst-inhibiting effect of acute third ventricle injections of cadmium (Cd 2+ ) and lead (Pb 2+ )

We have previously demonstrated that acute third ventricle injections of both lead and cadmium prevent the dipsogenic response elicited by dehydration or by central injections of dipsogenic agents such as angiotensin II, carbachol and isoproterenol in rats. We have also shown that the antidipsogenic action of cadmium may be due, at least in part, to activation of thirst-inhibitory central serotonergic pathways. In the present paper we show that in Wistar male rats the antidipsogenic effect of both lead acetate (3.0 nmol/rat) and cadmium chloride (3.0 nmol/rat) may be partially dependent on the activation of brain opiatergic pathways since central injections of naloxone (82.5 nmol/rat), a non-selective opioid antagonist, blunt the thirst-inhibiting effect of these metals. One hundred and twenty minutes after the second third ventricle injections, dehydrated animals (14 h overnight) receiving saline + sodium acetate displayed a high water intake (7.90 ñ 0.47 ml/100 g body weight) whereas animals receiving saline + lead acetate drank 3.24 ñ 0.47 ml/100 g body weight. Animals receiving naloxone + lead acetate drank 6.94 ñ 0.60 ml/100 g body weight. Animals receiving saline + saline drank 8.16 ñ 0.66 ml/100 g body weight whilst animals receiving saline + cadmium chloride drank 1.63 ñ 0.37 ml/100 g body weight. Animals receiving naloxone + cadmium chloride drank 8.01 ñ 0.94 ml/100 g body weight. It is suggested that acute third ventricle injections of both lead and cadmium exert their antidipsogenic effect by activating thirst-inhibiting opioid pathways in the brain

Lead (Pb+) and cadmium (Cd2+) inhibit the dipsogenic action of central beta-adrenergic stimulation by isoproterenol

We have previously demonstrated that acute third ventricle injections of both Pb2+ and Cd2+ impair the dipsogenic response elicited by three different situations: dehydration and central cholinergic or angiotensinergic stimulation. beta-Adrenergic activation is part of the multifactorial integrated systems operating in drinking behavior control in the central nervous system. In the present study acute third ventricle injections of Pb2+ (3,30 and 300 pmol/rat) or Cd2+ (0.3, 3 and 30 pmol/rat) blocked the dipsogenic response induced by third ventricle injections of isoproterenol (ISO; 160 nmol/rat) in a dose-dependent manner. Normohydrated animals receiving ISO + NaAc (sodium acetate) or saline (controls) displayed a high water intake after 120 min (ISO + saline = 5.78 ñ O.54 ml/lOO g; ISO + NaAc = 6.00 ñ O.6 ml/lOO g). After the same period,animals receiving ISO but pretreated with PbAc at the highest dose employed (300 pmol/rat) drank O.78 ñ O.23 ml/lOO g while those receiving ISO and pretreated with the highest dose of CdCl(2)(30 pmol/rat) presented a water intake of O.7 ñ O.30 ml/lOO g. Third ventricle injections of CdCl(2) (3 nmol/rat) or PbAc (3 nmol/rat) did not modify food intake in rats deprived of food for 24 h. Thus, general central nervous system depression explaining the antidipsogenic action of the metals can be safely excluded. It is concluded that both Pb2+ and Cd2+ inhibit water intake induced by central beta-adrenergic stimulation.

Envolvimento do ácido 5-aminolevulínico como espécie pro-oxidante no plumbismo e envelhecimento / Involvement of the 5-aminolevulinic acid as a pro-oxidant specie in plumbism and the aging process

O Saturnismo e a PAI representam porfirias relacionadas ao acúmulo de ALA, como resultado da inibiçäo de várias enzimas da via biossintética do heme pelo chumbo e defeito genético na biossíntese da PBG-desminase, respectivamente. Bechara et al (1993 - artigo de revisäo) propöem a auto-oxidaçäo da forma enólica do ALA catalisada por complexos de ferro, gerando espécies reativas de oxigênio e o radical ALA, como processo disparador dos sintomas observados nessas patologias. O efeito deletério destas espécies sobre importantes macromoléculas (proteínas, DNA) e estruturas celulares (mitocôndria, retículo endoplasmático) foi evidenciado em vários estudos in vivo e in vitro. O objetivo desta tese é estudar o envolvimento de ALA como espécie pro-oxidante no saturnismo e no processo de envelhecimento. Para tanto, foi necessário o desenvolvimento de um método de dosagem do ALA, pois os métodos até entäo descritos na literatura embora dotados de sensibilidade adequada, eram extremamente trabalhosos e lentos devido ao elevado número de etapas envolvidas na preparaçäo da amostra. O método aqui descrito utiliza a cromatografia em fase reversa em HPLC acoplado a um detector eletroquímico e a derivatizaçäo pré-coluna do ALA com omicron-ftalaldeído (OPA) a um produto indólico. De posse de um método simples e seletivo para a quantificaçäo do ALA, o passo seguinte foi analisar a correlaçäo dos níveis do ALA em plasma com os de chumbo eritrocitário, protoporfirina IX eritrocitária, superóxido dismutase eritrocitária, metehemoglobina (sangue) e quimioluminescência (urina) em amostras coletadas de indivíduos expostos ocupacionalmente ao chumbo. Os resultados obtidos indicaram um grau de correlaçäo acentuado entre vários dos parâmetros testados reforçando o papel do ALA como espécie pró-oxidante de relevância na etiologia do saturnismo. Além disso, foram determinados os níveis de ALA em plasma, fígado e cérebro de ratos caracterizados como adultos jovens (6-8 meses) e velhos (24 meses) e sua correlaçäo com parâmetros indicativos do status oxidativo destes animais. Foi observado um aumento significativo do ALA nos ratos velhos tanto em plasma como em fígado, sendo que o mesmo apresentou uma correlaçäo positiva em fígado e cérebro com ferro näo hemínico, carbonil proteína e "thiobarbituric acid reactive substances" (TBARS). Esses dados nos permitem inferir ao ALA um papel pró-oxidante no processo de envelhecimento

Effect of acute lead treatment on the in vivo thrombosis in mouse cerebral microvessels under hydrated and dehydrated conditions

Effect of water deprivation for 24 h on blood parameters and platelet aggregation in pial arterioles of lead-treated mice was investigated. Exposure to lead was made by intraperitoneal injections for 24 h of lead acetate dissolved in a 5% glucose solution vehicle. Three doses of lead were used, a low dose of 0.1 mg/kg, intermediate dose of 0.5 mg/kg and a high dose of 1.0 mg/kg. Adult male mice were divided into four groups of 10 each. Platelet aggregation in pial microvessels was induced photochemically, in vivo, in anaesthetized [urethane, 1 - 2 mg/g, i.p] animals by activation of circulating sodium fluorescein [0.1 mL of 5% solution /25g, i.v.] with an intense mercury light. The time required for the first platelet aggregate to appear in pial arterioles was significantly [P < 0.05] shorter [166 +/- 27, 154 +/- 58, 218 +/- 68 sec; in low, intermediate and high doses of lead, respectively] than in control [276 +/- 63 sec]. Dehydration significantly reduced both the time requied for the first platelet aggregate [61 +/- 21 vs 125 +/- 31 sec] and the time to full occlusion [134 +/- 18 vs 239 +/- 68 sec, lead-treated vs control, P < 0.05].Blood data of dehydrated mice confirmed haemoconcentration and lead treatment did not have any influence, except haemoglobin and haematocrit in the high dose group which showed significant differences from those of control [P < 0.05]. These data revealed that lead can cause cerebrovascular thrombosis after 24 h of exposure and its effect can be enhanced under water deprivation conditions

Riesgo plúmbico en imprentas de Lima Metropolitana y Callao / Plumbic risk in printing of Lima and Callao

Se relaciona los resultados obtenidos en trabajadores gráficos con intoxicación plúmbica aparentemente asintomática de diferentes imprentas tipográficas de Lima Metropolitana y sectores del Callao. Se agrupó 128 trabajadores según sexo, edad, tiempo de servicio, horas de trabajo, grado de intoxicación, de incidencia y oficio. Se determinó la concentración de plomo en sangre por el método de espectrofotometria de absorción atómica como un reflejo de la exposición laboral, obteniéndose en ayudantes de linotipistas:60.81 ug Pb por ciento y en cajistas 29.55 ug Pb por ciento, en linotipistas 48,44 ug Pb por ciento e imprsores 39.91 ug Pb por cientos estas últimas de incidencia media. El grado de absorción industrial de plomo en sangre esta relacionada con la ocupación que realiza. De las imprentas visitadas el 59 por ciento torna medidas de prevención, mientras que el 41 por ciento no se demuestra la existencia de trabajadores gráficos con una mayor concentración de plumbenig con respecto a los límites máximos permisibles en industrias. Se concluye que la carencia de medidas de protección, prevención y hábitos ocupacionales inadecuados, son factores que condicionan con mayor riesgo plumbico.

Inhibition of cytokinesis by lead (Pb2+) in a centric diatom.

Effect of inorganic and organo lead has been studied on the mitosis of a centric diatom Cyclotella meneghiniana f. unipunctata. Binucleate cells were formed in the presence of different concentrations of Pb2+ (1.0, 2.0, 3.0 and 5.0 mM) due to inhibition of cell plate formation. Lead at 5.0 mM concentration was more inhibitory than the other concentrations. Organo lead was a powerful depressant of cytokinesis than inorganic lead. Failure of cytokinesis might be due to disruption of microtubules. Formation of distinct nuclei delayed post incubation cell divisions suggest partial damage of mitotic spindles.

Effect of lead on nitrogenase and enzymes of nitrogen assimilation in a cyanobacterium Nostoc muscorum.

Lead decreased the growth rates, total cell mass, heterocyst frequency, total cell protein, nitrogenase activity, glutamine synthetase (GS) and glutamate synthase (GOGAT) activities in N:muscorum. However, lead at 0.01 and 10 micrograms ml-1 conc. enhanced nitrogenase as well as GS activity of the cells. On transfer to excess lead (100 micrograms ml-1), nitrogenase and GS activities ceased almost after 24 hr in the cyanobacterium. It is deduced that lead has a two step effect on stimulation and inhibition of metabolic activity at 0.01 and 10 micrograms ml-1 concentration and 0.1 and 100 micrograms ml-1 concentration respectively indicating a close interaction between nitrogen fixation and GS activity. However, GOGAT activity is an exception to this two step stimulation and inhibition process.

Alterations in plasma sodium and potassium levels following chronic oral ingestion of lead, mercury and cadmium in male albino rats.

Adult male albino rats were orally administered 0, 25, 50 and 100 ppm of lead nitrate, mercuric chloride and cadmium chloride for 60, 120 and 180 days. The plasma sodium levels were decreased in rats exposed to varying doses of lead and mercury up to 180 days, while animals which consumed cadmium chloride showed an increase in sodium levels. In lead and mercury treated animals, plasma potassium levels were increased up to 180 days. The levels were decreased in cadmium exposed rats. These observations suggest that chronic exposure to these heavy metals considerably influences plasma sodium and potassium levels depending on the dose and duration of exposure.

postnatal development of the visual cortex of albino rat and inorganic lead

Albino rats were used in the present study. Two groups of pregnant female animals, one served as control and other as experimental. The experimental mothers were fed with chow, tap water and libitum and 1% lead carbonate, from the first day of parturition. The pups from both groups were taken at the postnatal ages of 3, 9, 12, 15 and 21 days from both groups. Brains were extracted and fixed in 10% neutral formalin. The primary visual cortex was located according to Krieg [1946] map. It was processed for histological technique. Sagittal sections were cut at 10 u thick and stained with Einarsons gallocyanine. This study showed that the development of rat visual cortex is competed about day 21, when the neurons achieve their mature appearance as indicated by the increased size of cell body and nuclei; differentiation of the cells; the nuclei became vesicular with prominent nucleoli and increase Nissl's granules and there was also an increase in thickness of the cortex and a decreased packing of the neurons. The offsprings of rats fed on the inorganic lead starting from day 89, had an extensive changes compared to age matched control. Stratification of the visual cortex comes less distinct all over the ages used. Maturation of layer V and layer II/III is delayed. There is also cavitation, and neurocytic chromatolysis which is pronounced at day 12 and is clearly distinct at day 15. Pericapillary and capillary dilatation are noticed

Effect of selected metal ions on the motility and carbohydrate metabolism of ejaculated human spermatozoa.

Zinc, lead and cadmium in the form of chloride salts when added to a standard assay system containing 80 X 10(-6) ejaculated washed human spermatozoa caused a dose and duration-dependent inhibition of their motility. The activity of certain key enzymes of carbohydrate and energy metabolism, viz, glycogen phosphorylase, glucose-6-phosphatase, fructose-1, 6-diphosphatase, glucose-6-phosphate isomerase, amylase, Mg2+- dependent ATPase and lactic and succinic acid dehydrogenases were also found to be inhibited. The order of inhibitory effects of the heavy metals were zinc less than lead less than cadmium. The metal chelating agent, ethylene diamine tetra-acetic acid (EDTA, disodium salt) also interfered with the spermatozoal motility and inhibited the enzyme activities.

Papel dos indicadores biológicos na avaliaçäo da exposiçäo ocupacional ao chumbo / The role of biological indicators used in the control of occupational exposure to lead

A partir de um minucioso levantamento bibliográfico, os autores realizam um trabalho de revisäo abordando o papel dos indicadores biológicos atualmente utilizados para o controle da exposiçäo ao chumbo. Säo feitas consideraçöes sobre o mecanismo de açäo tóxica do metal, com ênfase sobre os sistemas hematopoético, nervoso e renal. Säo destacados os parâmetros bioquímicos que atuam como indicadores de absorçäo ou de efeito, com vista ao controle da saúde do trabalhador exposto ao xenobiótico

Interferência do chumbo na atividade enzimática da anidrase carbônica / Interference of lead in the enzymatic activity of carbon anhydrase

Foram estudadas as variaçöes ocorridas com as atividades enzimáticas do ácido delta-aminolevulínico desidratase, e da anidrase carbônica eritrocitária, em grupos de operários. Determinou-se que operários expostos, ocupacionalmente, ao chumbo, apresentam, além da diminuiçäo da atividade da ALA-D, também a diminuiçäo da atividade da anidrase carbônica