Parental and preimaginal exposure to methylmercury disrupts locomotor activity and circadian rhythm of adult Drosophila melanogaster.

Methylmercury (MeHg) is a well-known toxic pollutant. However, little is known about the effects of this toxic agent in an adult as a consequence of a parental or preimaginal exposure. This study used Drosophila melanogaster to investigate whether a parental or a preimaginal (eggs-larvae-pupae stages) exposure could impact parameters as viability, locomotor activity, and sleep patterns of fruit flies. Thus, we performed two exposure protocols. One where just parents were exposed to MeHg (0-12 µM) during 24 h, then flies were transferred to lay eggs in a healthy medium (without MeHg). In the other, flies were set to lay eggs in a MeHg medium, same concentrations, and discarded after this (preimaginal exposure). Viability was evaluated from egg to adult flies. F1 progeny was collected within 24 h and transferred to a fresh healthy medium. Sleep behavior analysis was performed using Drosophila Active Monitoring System (DAMS), and the locomotor activity was evaluated by climbing assay. Results have shown that the parental exposure had a significant impact on F1 progeny reducing viability and locomotor activity performance, but no significant circadian rhythm alterations. Whereas the preimaginal exposure had a stronger effect decreasing viability and locomotor activity, it also disrupted sleep patterns. MeHg preimaginal exposure showed a longer sleep duration and lower daily activity. Results corroborate the hypothesis that low MeHg exposure could trigger subclinical symptoms related to a 'neurotoxicological development effect'. Complementary investigations could clarify the underlying mechanisms of MeHg effects in neural functions due to parental and early development exposure to this toxicant.

Guarana improves behavior and inflammatory alterations triggered by methylmercury exposure: an in vivo fruit fly and in vitro neural cells study.

Methylmercury (MeHg) is a well-known environmental pollutant associated with neurological and developmental deficits in animals and humans. However, epidemiological data showed that people living in the Amazon region although exposed to MeHg do not present these effects probably due to the protective effect of certain foods. We hypothesized here if guarana, a highly caffeinated fruit and consumed on a daily basis by Amazon people, could have some protective effect against MeHg toxicity using two complementary approaches. To assess locomotor impairment and sleep disruption, we used fruit fly (Drosophila melanogaster) model, and to evaluate neuroinflammation, we used human SH-SY5Y neural cells by measuring inflammatory cytokines levels. Results showed that guarana had a protective effect on the locomotor activity of male fruit flies reducing the excessive sleepiness caused by MeHg and increasing daily activity. Also, guarana increased the viability of flies and attenuated neural cells mortality. In addition, guarana reduced all pro-inflammatory cytokines levels increased by MeHg, along with caspase-1, caspase -3, caspase-8, and 8-dOHG levels, whereas increased the anti-inflammatory (IL-10) cytokine levels, which was decreased by MeHg. Our study provides new insights on the protective effects of guarana on the viability, locomotor activity, sleep, and activity patterns in vivo and the in vitro neuronal anti-inflammatory effect against MeHg toxicity.

DNA damage and postural balance in multiple sclerosis patients / Dano ao DNA e equilíbrio postural de portadores de Esclerose Múltipla

Abstract Introduction: Multiple Sclerosis (MS) is a chronic inflammatory disease characterized by infiltration of inflammatory cells on the Central Nervous System (CNS). There is evidence that cumulative DNA damage can contribute to various mechanisms underlying MS lesions. Changes in postural balance are frequent observations in subjects with MS. Objective: Evaluated the DNA damage index (DDI)) and postural balance in patients with MS. Methods: A case-control study was conducted with 28 subjects matched for sex, age, and body mass index, divided into MS group and control. The DDI was assessed by comet assay and postural balance through recording the body oscillations of the center of pressure (COP), in the anterior-posterior and lateral middle directions. Results: Showed higher DDI in MS patients (21.3 ± 4.8) than controls (7.9 ± 6.1). Significant differences between groups were also noted in postural control parameters. The wider ranges of postural sway were observed in the MS group. The associations between DDI and postural control parameters showed weak, but significant correlations. No associations were found between DDI and time of diagnosis of MS. Conclusion: People with MS had higher DDI and larger body oscillations than healthy individuals.

Resumo Introdução: A Esclerose Múltipla (EM) é uma doença inflamatório crônica caracterizada pela infiltração de células inflamatórias no Sistema Nervoso Central (SNC). Há evidencias de que danos cumulativos ao DNA possam contribuir para vários mecanismos subjacentes às lesões da EM. As alterações no equilíbrio postural são observações frequentes nos sujeitos com EM. Objetivo: Este estudo avaliou os índices de dano ao DNA (ID) e equilíbrio postural em portadores de Esclerose Múltipla (EM). Métodos: Um estudo de caso-controle foi conduzido com 28 sujeitos pareados por sexo, idade e índice de massa corporal, divididos em grupo EM e controle. O ID foi avaliado pelo ensaio cometa e o equilibro postural através do registro das oscilações corporais relativas ao deslocamento centro de pressão (COP) nas direções antero posterior e médio lateral. Resultados: Maiores ID em portadores de EM (21,3 ± 4,8) do que controles (7,9 ± 6,1). Diferenças significativas entre os grupos também foram percebidas nos parâmetros do controle postural. As maiores amplitudes de oscilação foram observadas no grupo EM para ambas as direções. As associações entre o ID e parâmetros do controle postural apresentaram correlações fracas e significativas. Não foram encontradas associações entre ID e tempo de diagnóstico de EM. Conclusão: Portadores de EM apresentaram maior ID e maiores oscilações corporais do que controles saudáveis.

Apoptotic markers and DNA damage are related to late phase of stroke: Involvement of dyslipidemia and inflammation.

Oxidative stress and brain inflammation are thought to contribute to the pathophysiology of cerebral injury in acute stroke, leading to apoptosis and cell death. Lipid accumulation may lead to progression of carotid plaques and inflammation, contributing to increased acute stroke risk. However, little is known about these events and markers in the late stroke (>6 months) and if dyslipidemia could contribute to disease's pathophysiology in a later phase. In this case-control study, we recruited patients in the late stroke phase (n=40) and health subjects (control group; n = 40). Dichlorodihydrofluorescein (DCFH), nitrite/nitrate (NOx), Tumor necrosis factor-alpha (TNF-α), Acetylcholinesterase (AChE), Caspase 8 (CASP 8), Caspase 3 (CASP 3) and Picogreen (PG) were measured in periphery blood samples. Furthermore, a correlation among all measured markers (DCFH, NOx, TNF-α, AChE, CASP 8, CASP 3 and PG) was realized. The marker levels were also compared to triglycerides (TG), total (CHO), LDL and HDL cholesterol levels and medications used. Statistical analyses showed that stroke patients presented an increase of DCFH, NOx, TNF-α and AChE levels when compared to control subjects. In addition, we observed that stroke patients had significantly higher CASP 8, CASP 3 and PG levels than control group. A significant correlation between TNF-α with CASP 8 (r = 0.4) and CASP 3 (r = 0.4) levels was observed, but not with oxidative/nitrosative markers. Moreover, we observed that stroke patients with dyslipidemia had significantly higher TNF-α, CASP 8 and CASP 3 levels than stroke without dyslipidemia and control groups. Our findings suggest that oxidative and inflammatory markers may be still increased and lead to caspase activation and DNA damage even after 6 months to cerebral injury. Furthermore, it is plausible to propose that dyslipidemia may contribute to worsen proinflammatory state in a later phase of stroke and an increased risk to new neurovascular events.

Methotrexate-related response on human peripheral blood mononuclear cells may be modulated by the Ala16Val-SOD2 gene polymorphism.

Methotrexate (MTX) is a folic acid antagonist used in high doses as an anti-cancer treatment and in low doses for the treatment of some autoimmune diseases. MTX use has been linked to oxidative imbalance, which may cause multi-organ toxicities that can be attenuated by antioxidant supplementation. Despite the oxidative effect of MTX, the influence of antioxidant gene polymorphisms on MTX toxicity is not well studied. Therefore, we analyzed here whether a genetic imbalance of the manganese-dependent superoxide dismutase (SOD2) gene could have some impact on the MTX cytotoxic response. An in vitro study using human peripheral blood mononuclear cells (PBMCs) obtained from carriers with different Ala16Val-SOD2 genotypes (AA, VV and AV) was carried out, and the effect on cell viability and proliferation was analyzed, as well as the effect on oxidative, inflammatory and apoptotic markers. AA-PBMCs that present higher SOD2 efficiencies were more resistance to high MTX doses (10 and 100 µM) than were the VV and AV genotypes. Both lipoperoxidation and ROS levels increased significantly in PBMCs exposed to MTX independent of Ala16Val-SOD2 genotypes, whereas increased protein carbonylation was observed only in PBMCs from V allele carriers. The AA-PBMCs exposed to MTX showed decreasing SOD2 activity, but a concomitant up regulation of the SOD2 gene was observed. A significant increase in glutathione peroxidase (GPX) levels was observed in all PBMCs exposed to MTX. However, this effect was more intense in AA-PBMCs. Caspase-8 and -3 levels were increased in cells exposed to MTX, but the modulation of these genes, as well as that of the Bax and Bcl-2 genes involved in the apoptosis pathway, presented a modulation that was dependent on the SOD2 genotype. MTX at a concentration of 10 µM also increased inflammatory cytokines (IL-1ß, IL-6, TNFα and Igγ) and decreased the level of IL-10 anti-inflammatory cytokine, independent of SOD2 genetic background. The results suggest that potential pharmacogenetic effect on the cytotoxic response to MTX due differential redox status of cells carriers different SOD2 genotypes.

Association between Machado-Joseph disease and oxidative stress biomarkers.

Spinocerebellar ataxia type 3, also called Machado-Joseph disease (MJD), is an hereditary autosomal dominant neurodegenerative disease that affects the cerebellum and its afferent and efferent connections. Since the mechanism by which mutant ataxin-3 eventually leads to neuronal death is poorly understood, additional investigations to clarify the biological alterations related to Machado-Joseph disease are necessary. Recent investigations suggest that oxidative stress may contribute significantly to Machado-Joseph disease. We compared markers of oxidative stress between Machado-Joseph disease and healthy control subjects. The results showed that Machado-Joseph patients have higher catalase levels and lower thiol protein levels compared to control subjects. The peripheral blood lymphocyes of MJD patients also showed higher levels of DNA damage by the comet assay than control subjects. Our results corroborate the hypothesis that the oxidative stress is associated with MJD patients. However, whether strategies to increase cellular antioxidative capacity may be effective therapies for the treatment of Machado-Joseph disease is an open question.

Cisplatin effects on guinea pigs: cochlear histology and genotoxicity.

UNLABELLED: To understand how the DNA answers to external agents such as cisplatin may be relevant to the diagnosis and treatment of hearing disorders caused by the administration of such drug. OBJECTIVES: To investigate the cisplatin influence on the cochlea and DNA of guinea pigs. MATERIAL AND METHODS: Experimental study carried out with 12 guinea pigs (Cavia porcellus). The inclusion criterion was the presence of Preyer's reflex and distortion-product otoacoustic emissions. Guinea pigs were divided into two groups: Control Group (CG)--made up of six guinea pigs, to which we administrated saline solution during six consecutive days, intraperitoneally; and a Study Group (SG)--made up of six guinea pigs, to which we administrated cisplatin during six consecutive doses of 3mg/kg/day intraperitoneally. Twenty-four hours after the last administration of cisplatin the guinea pigs were slaughtered, blood samples were collected and the cochleae were removed. RESULTS: The administration of cisplatin did not cause identifiable changes to the DNA. Histological analysis showed changes in the organ of Corti and spiral ganglion. CONCLUSION: Cisplatin causes changes in cochlear histology, such as the loss of the normal micro-cytoarchitecture of the organ of Corti, and reduction of neurons of the spiral ganglion with cell alterations, however, DNA damage was not detected.

Efeitos da cisplatina em cobaias: histologia coclear e genotoxidade / Cisplatin effects on guinea pigs: cochlear histology and genotoxicity

Conhecer as respostas do DNA aos agentes externos como a cisplatina pode ser relevante para o diagnóstico e tratamento das alterações auditivas causadas pela administração deste fármaco. OBJETIVOS: Verificar a influência da cisplatina sobre a cóclea e o DNA de cobaias. MATERIAL E MÉTODO: Estudo experimental executado com 12 cobaias (Cavia porcellus). O critério de inclusão de cobaias na amostra foi a presença de reflexo de Preyer e emissões otoacústicas produto de distorção (EOAPDs). As cobaias foram dividas em dois grupos: Grupo controle (GC) - composto de seis cobaias, às quais foi administrada solução fisiológica por seis dias consecutivos, via intraperitoneal; Grupo estudo (GE) - composto por seis cobaias, às quais foi administrada cisplatina em seis doses consecutivas de 3mg/kg/dia via intraperitoneal. Vinte e quatro horas após a última aplicação de cisplatina as cobaias foram sacrificadas, foi coletada amostra sanguínea e as cócleas foram removidas. RESULTADOS: Administração de cisplatina não provocou alterações genotóxicas. A análise histológica mostrou alterações no órgão de Corti e gânglio espiral. CONCLUSÃO: A cisplatina provoca alterações na histologia coclear como perda da microcitoarquitetura normal do órgão de Corti e redução dos neurônios do gânglio espiral com alterações celulares. No entanto, não foram detectados danos genotóxicos.

To understand how the DNA answers to external agents such as cisplatin may be relevant to the diagnosis and treatment of hearing disorders caused by the administration of such drug. OBJECTIVES: To investigate the cisplatin influence on the cochlea and DNA of guinea pigs. MATERIAL AND METHODS: Experimental study carried out with 12 guinea pigs (Cavia porcellus). The inclusion criterion was the presence of Preyer's reflex and distortion-product otoacoustic emissions. Guinea pigs were divided into two groups: Control Group (CG) - made up of six guinea pigs, to which we administrated saline solution during six consecutive days, intraperitoneally; and a Study Group (SG) - made up of six guinea pigs, to which we administrated cisplatin during six consecutive doses of 3mg/kg/day intraperitoneally. Twenty-four hours after the last administration of cisplatin the guinea pigs were slaughtered, blood samples were collected and the cochleae were removed. RESULTS: The administration of cisplatin did not cause identifiable changes to the DNA. Histological analysis showed changes in the organ of Corti and spiral ganglion. CONCLUSION: Cisplatin causes changes in cochlear histology, such as the loss of the normal micro-cytoarchitecture of the organ of Corti, and reduction of neurons of the spiral ganglion with cell alterations, however, DNA damage was not detected.