RESUMO Celtis iguanaea (Jacq.) Sargent é uma planta usada popularmente para tratar infecções do trato urinário, rim, mama, dores no corpo, reumatismo, asma, cólicas, má digestão e também é usada como diurético. Este trabalho objetivou determinar a toxicidade aguda do extrato aquoso de folhas de Celtis iguanaea (Jacq.) Sargent em roedores. Após os processos de coleta, identificação, secagem e moagem, o pó liofilizado das folhas da planta foi utilizado para produzir o seu extrato aquoso por infusão e então dissolvido em solução salina a 0.9 %. A administração foi feita por gavagem na dose de 2000 mg kg-1 em ratos e camundongos de ambos os sexos. A toxicidade oral foi determinada de acordo com o guia 423 da OECD. Sinais de toxicidade foram observados por 15 dias e tabulados de 0 a 4, respectivamente, como ausentes, raros, leves, moderados e graves. Foi acompanhado o peso dos animais e parâmetros fisiológicos tais como alimentação e excreções. Amostras do tecido de todo o animal foram coletadas para análise histológica. A toxicidade encontrada para o extrato foi incluída na classe 5 (substâncias com DL50 superior a 2000 mg kg-1 e menor que 5000 mg kg-1) sendo considerada baixa, porém, as observações histopatológicas sugerem nefrotoxicidade e cardiotoxicidade. O peso absoluto dos rins e coração de ratos e camundongos machos aumentou, porém, não houve aumento significativo no peso relativo dos órgãos dos animais.

RESUMO Celtis iguanaea (Jacq.) Sargent is popularly used to treat urinary infections, kidneys, breast, body aches, rheumatism, asthma, cramps, poor digestion and as a diuretic medicine. This study aims to determine the acute toxicity of the aqueous leaf extract of Celtis iguanaea (Jacq.) Sargent in rodents. After the collection processes, identification, drying and grinding, the lyophilized powder of the leaves produced, by infusion, the aqueous extract and it was dissolved in saline 0.9%. The administration was made by gavage at a dose of 2000 mg kg-1to rats and mice of both genders. The oral toxicity was determined according to the OECD 423 guide. Signs of toxicity were observed for 15 days and classified from 0 to 4 respectively as missing, rare, mild, moderate and severe. The weight of the animals and the physiological parameters such as food intake and excrements production were observed. All animal tissue samples were collected for histological analysis. The extract was included in Type 5 (substance with LD50 higher than 2000 mg kg-1 and less than 5000 mg kg-1), being considered of low toxicity, but the histopathologycal findings suggested nephrotoxicity and cardiotoxicity. The absolute weight of the kidneys and the heart of the male rats and mice increased, but there was no significant raise in the relative weight of the animals’ organs.

The purpose of the present study was to measure contrast sensitivity to equiluminant gratings using steady-state visual evoked cortical potential (ssVECP) and psychophysics. Six healthy volunteers were evaluated with ssVECPs and psychophysics. The visual stimuli were red-green or blue-yellow horizontal sinusoidal gratings, 5° × 5°, 34.3 cd/m2 mean luminance, presented at 6 Hz. Eight spatial frequencies from 0.2 to 8 cpd were used, each presented at 8 contrast levels. Contrast threshold was obtained by extrapolating second harmonic amplitude values to zero. Psychophysical contrast thresholds were measured using stimuli at 6 Hz and static presentation. Contrast sensitivity was calculated as the inverse function of the pooled cone contrast threshold. ssVECP and both psychophysical contrast sensitivity functions (CSFs) were low-pass functions for red-green gratings. For electrophysiology, the highest contrast sensitivity values were found at 0.4 cpd (1.95 ± 0.15). ssVECP CSF was similar to dynamic psychophysical CSF, while static CSF had higher values ranging from 0.4 to 6 cpd (P < 0.05, ANOVA). Blue-yellow chromatic functions showed no specific tuning shape; however, at high spatial frequencies the evoked potentials showed higher contrast sensitivity than the psychophysical methods (P < 0.05, ANOVA). Evoked potentials can be used reliably to evaluate chromatic red-green CSFs in agreement with psychophysical thresholds, mainly if the same temporal properties are applied to the stimulus. For blue-yellow CSF, correlation between electrophysiology and psychophysics was poor at high spatial frequency, possibly due to a greater effect of chromatic aberration on this kind of stimulus.

Ventilatory differences between rat strains and genders have been described but the morphology of the phrenic nerve has not been investigated in spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. A descriptive and morphometric study of the phrenic nerves of male (N = 8) and female (N = 9) SHR, and male (N = 5) and female (N = 6) WKY is presented. After arterial pressure and heart rate recordings, the phrenic nerves of 20-week-old animals were prepared for epoxy resin embedding and light microscopy. Morphometric analysis performed with the aid of computer software that took into consideration the fascicle area and diameter, as well as myelinated fiber profile and Schwann cell nucleus number per area. Phrenic nerves were generally larger in males than in females on both strains but larger in WKY compared to SHR for both genders. Myelinated fiber numbers (male SHR = 228 ± 13; female SHR = 258 ± 4; male WKY = 382 ± 23; female WKY = 442 ± 11 for proximal right segments) and density (N/mm²; male SHR = 7048 ± 537; female SHR = 10355 ± 359; male WKY = 9457 ± 1437; female WKY = 14351 ± 1448) for proximal right segments) were significantly larger in females of both groups and remarkably larger in WKY than SHR for both genders. Strain and gender differences in phrenic nerve myelinated fiber number are described for the first time in this experimental model of hypertension, indicating the need for thorough functional studies of this nerve in male and female SHR.

We measured visual performance in achromatic and chromatic spatial tasks of mercury-exposed subjects and compared the results with norms obtained from healthy individuals of similar age. Data were obtained for a group of 28 mercury-exposed subjects, comprising 20 Amazonian gold miners, 2 inhabitants of Amazonian riverside communities, and 6 laboratory technicians, who asked for medical care. Statistical norms were generated by testing healthy control subjects divided into three age groups. The performance of a substantial proportion of the mercury-exposed subjects was below the norms in all of these tasks. Eleven of 20 subjects (55%) performed below the norms in the achromatic contrast sensitivity task. The mercury-exposed subjects also had lower red-green contrast sensitivity deficits at all tested spatial frequencies (9/11 subjects; 81%). Three gold miners and 1 riverine (4/19 subjects, 21%) performed worse than normal subjects making more mistakes in the color arrangement test. Five of 10 subjects tested (50%), comprising 2 gold miners, 2 technicians, and 1 riverine, performed worse than normal in the color discrimination test, having areas of one or more MacAdam ellipse larger than normal subjects and high color discrimination thresholds at least in one color locus. These data indicate that psychophysical assessment can be used to quantify the degree of visual impairment of mercury-exposed subjects. They also suggest that some spatial tests such as the measurement of red-green chromatic contrast are sufficiently sensitive to detect visual dysfunction caused by mercury toxicity.

Four populations in the Amazon area were selected for a comparative study of mercury-exposed and non-exposed populations: São Luiz do Tapajós, Barreiras, Panacauera, and Pindobal Grande. The highest mercury levels in human hair samples were found in São Luiz do Tapajós and Barreiras, greatly exceeding the limits established by the World Health Organization. Panacauera showed an intermediate level below 9 µg/g. This was the first comparative and simultaneous evaluation of mercury exposure in the Amazon area. Also, thanks to this type of monitoring, we were able to eliminate the uncertainties about the reference dose. On the basis of these data, we can conclude that the mercury levels detected in exposed populations of the Tapajós River basin may be dangerous not only because they are above the World Health Organization limits, but also because the simultaneous mercury detection in non-exposed populations with similar characteristics provided a valid control and revealed lower mercury levels. Our results support the importance of continuous monitoring in both exposed and non-exposed populations.