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Porto Moniz, Portugal

Carvalho M.L.,University of Lisbon | Geraldes V.,Instituto Of Fisiologia | Rocha I.,Instituto Of Fisiologia
Metallomics | Year: 2012

The accumulation of lead in several bones of Wistar rats with time was determined and compared for the different types of bones. Two groups were studied: a control group (n = 20), not exposed to lead and a contaminated group (n = 30), exposed to lead from birth, first indirectly through mother's milk, and then directly through a diet containing lead acetate in drinking water (0.2%). Rats age ranged from 1 to 11 months, with approximately 1 month intervals and each of the collections had 3 contaminated rats and 2 control rats. Iliac, femur, tibia-fibula and skull have been analysed by Energy Dispersive X-ray Fluorescence Technique (EDXRF). Samples of formaldehyde used to preserve the bone tissues were also analysed by Electrothermal Atomic Absorption (ETAAS), showing that there was no significant loss of lead from the tissue to the preservative. The bones mean lead concentration of exposed rats range from 100 to 300 μg g -1 while control rats never exceeded 10 μg g -1. Mean bone lead concentrations were compared and the concentrations were higher in iliac, femur and tibia-fibula and after that skull. However, of all the concentrations in the different collections, only those in the skull were statistically significantly different (p < 0.05) from the other types of bones. Analysis of a radar chart also allowed us to say that these differences tend to diminish with age. The Spearman correlation test applied to mean lead concentrations showed strong and very strong positive correlations between all different types of bones. This test also showed that mean lead concentrations in bones are negatively correlated with the age of the animals. This correlation is strong in iliac and femur and very strong in tibia-fibula and skull. It was also shown that the decrease of lead accumulation with age is made by three plateaus of accumulation, which coincide, in all analysed bones, between 2nd-3rd and 9th-10th months. © 2012 The Royal Society of Chemistry. Source

Guimaraes D.,New University of Lisbon | Carvalho M.L.,University of Lisbon | Geraldes V.,Instituto Of Fisiologia | Rocha I.,Instituto Of Fisiologia | And 2 more authors.
Journal of Trace Elements in Medicine and Biology | Year: 2012

The concentration of lead in liver and kidneys of Wistar rats, fed with lead since fetal period in relation to their age and to a control group, was determined. A group of rats was exposed to lead acetate (n= 30) in drinking water and the other group was exposed to normal water (n= 20). Samples were collected from rats aging between 1 and 11 months and were analyzed by Energy Dispersive X-ray Fluorescence (EDXRF) without any chemical preparation. The EDXRF results were assessed by the PIXE (Proton Induced X-ray Emission) technique. The formaldehyde used to preserve the samples was also analyzed by ETAAS (Electro-Thermal Atomic Absorption Spectrometry) in order to verify if there was any loss of lead from the samples to the formaldehyde. We found that the loss was not significant (<2%).Concerning the mean values of the lead concentration measured in the contaminated soft tissues, in liver they range from 6 to 22μgg-1, and in kidneys from 44 to 79μgg-1. The control rats show, in general, values below the EDXRF detection limit (2μgg-1). The ratio kidney/liver ranges from 2 to 10 and is strongly positively correlated with the age of the animals. A Spearman correlation matrix to investigate the correlation between elemental concentrations and the dependence of these concentrations with age showed that there is a strong positive correlation with age for lead in the liver but not in the kidney. The correlation matrix showed also that the concentration of lead in these two soft tissues is not correlated. The lead accumulation in liver is made by different plateaus that strongly decrease with age. It was verified the existence of two levels of accumulation in kidney, not very highlighted, which might be indicative of a maximum accumulation level for lead in kidney. © 2012 Elsevier GmbH. Source

Guimaraes D.,New University of Lisbon | Carvalho M.L.,University of Lisbon | Becker M.,Leibniz Institute for Analytical Sciences | Von Bohlen A.,Leibniz Institute for Analytical Sciences | And 3 more authors.
X-Ray Spectrometry | Year: 2012

Measurements made in feces and urine of Wistar rats exposed to lead acetate (n=20) in drinking water since the fetal period were compared with those obtained from a control group (n=20) in order to assess the age influence on Pb excretion. The measurements were made in different collections of rats aging between 1 and 11months. To determine the Pb content of the samples, total reflection X-ray fluorescence (TXRF) and electrothermal atomic absorption spectrometry (ETAAS) were used for the urine samples and energy dispersive X-ray fluorescence (EDXRF) was used for the feces. The results show high concentrations of Pb being eliminated from the organism by urine and feces in contaminated rats. Values vary from (600±140)μgl -1 to (5 460±115)μgl -1 in urine and from (4 500±300)μgg -1 to (11 400±3 300)μgg -1 in dry feces. The control rats show, in general, low lead concentrations or below detection limits. The fecal/urinary ratio was studied. It was shown to be about three to four orders of magnitude and positively correlated with time. It was verified in feces and urine that excretion decreases with the animal age and that this decrease is made by different levels of excretion. The excretions of Pb in urine and in feces are positively correlated. A good agreement was found between the results obtained with TXRF and ETAAS for urine samples. This work also stresses the suitability of these techniques in the study of Pb intoxication. © 2011 John Wiley & Sons, Ltd. Source

Guimaraes D.,New University of Lisbon | Santos J.P.,New University of Lisbon | Carvalho M.L.,University of Lisbon | Vale G.,New University of Lisbon | And 8 more authors.
Talanta | Year: 2011

An ultrasonic assisted solid-liquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n = 9) and 7% (n = 3) respectively. The limit of quantification was 1.05 μg g -1 for brain samples and 2.1 μg L -1 for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from1.9 ± 0.2 μg g -1 to 3.5 ± 0.2 μg g -1 and from 752 ± 56 μg L -1 to 60.9 ± 1.2 mg L -1 respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats. © 2011 Elsevier B.V. All rights reserved. Source

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