Evidence of mercury biomagnification in the food chain of the cardinal tetra Paracheirodon axelrodi (Osteichthyes: Characidae) in the Rio Negro, central Amazon, Brazil.

In this study, nitrogen stable isotope (δ(15) N) and total mercury (THg) analyses were conducted on algae, submersed and emergent macrophytes, shrubs and trees, Macrobrachium sp. and Paracheirodon axelrodi collected in three streams that drain a large interfluvial region in the middle Rio Negro, Amazonas State, Brazil. Samples were collected during different hydrological periods over 12 months in lower stream reaches and their headwaters; the latter being characterized by shallow, open-canopy swamps. Additionally, δ(15) N values and mercury concentrations of Paracheirodon simulans and Cichla spp. from the middle Rio Negro were analysed to demonstrate THg biomagnification in the food web. The highest mercury levels of P. axelrodi were found in small individuals, which were collected principally in the low water period. The log10 THg-δ(15) N relationship of vascular plants and algae, Macrobrachium sp., Paracheirodon spp. and Cichla spp. showed significant mercury biomagnification among trophic levels, with regression slopes of 0·15 and 0·25 for the entire food web and heterotrophs-only food web, respectively. The mean ± s.d. THg concentrations for Macrobrachium sp., P. axelrodi, P. simulans and Cichla spp. were 63·6 ± 23·7, 104·5 ± 40·0, 112·3 ± 31·4 and 418·5 ± 188·1 ng g(-1) wet mass, respectively. Elevated levels of mercury found in Paracheirodon spp. and top predators such as Cichla spp. in a remote area far from anthropogenic inputs provide evidence that high mercury concentrations occur naturally in Rio Negro aquatic food webs.

Sertraline and fluoxetine: safe treatments for children and adolescents with epilepsy and depression.

OBJECTIVE: Depression is frequent, underdiagnosed, and untreated in people with epilepsy. The lack of treatment is partially explained by the concerns over the proconvulsive effects of psychoactive drugs. There are few studies on the effects of selective serotonin reuptake inhibitors (SSRIs) in adults with epilepsy and none in children. The main purpose of the present study was to analyze the impact of SSRIs on the severity and frequency of seizures in children and adolescents with epilepsy and major depressive disorders. In addition, we also evaluated the efficacy of SSRIs in the treatment of depressive symptoms and side effects other than seizure aggravation. METHODS: Monthly frequency of seizures was recorded in the 3-6 months preceding the introduction of SSRIs. According to the criteria proposed by A.M. Kanner, A.M. Kozak and M. Frey (Epilepsy Behav 2000;1:100-5), a positive correlation between introduction of SSRIs and seizure worsening should be considered in the following circumstances: (1) occurrence of de novo generalized tonic-clonic (GTC) seizures; (2) recurrence of GTC seizures following a period of at least 1 year without such episodes; and (3) increase in monthly seizure frequency compared with that reported before introduction of SSRIs. Seizure worsening was considered as probably caused by an SSRI when the increase in monthly frequency occurred in a period up to 3 months after the beginning of SSRI use. RESULTS: Thirty-six children with epilepsy had a depressive disorder. Seizures worsened in two patients. Among this group of patients with depression, all had an improvement in their depressive symptoms. One patient taking fluoxetine had a facial rash and one patient taking sertraline had gastrointestinal disorders. These conditions improved, with total remission, when fluoxetine was replaced with sertraline and vice versa. CONCLUSION: In this sample of children and adolescents with epilepsy and depressive disorders, we observed that SSRIs are a good therapeutic option, considering their efficacy in remission of depressive symptoms, their few adverse effects, and their maintenance of satisfactory seizure control. Treatment of depression should be considered relevant in the treatment of patients with epilepsy.