The effects of heavy metals on the incidence of morphological deformities in Chironomidae (Diptera)

Streams in urban areas are strongly impacted by the input of organic matter and metals, for instance copper (Cu) and zinc (Zn). These metals are essential for the aquatic biota, but when absorbed in excess they are toxic. In Chiro nomidae larvae, the deleterious effects of heavy metals can be ascertained by analyzing the morphological deformities of the larval mentum, a structure of the oral cavity. In this study, we evaluated I) the bioavailability of Cu and Zn in urban stream sediments and II) the relationship between Cu and Zn concentrations and the incidence of deformities in the mentum of Chironomus larvae. Chironomid flies were collected from four locations in two streams at an urban area in southern Brazil. They were identified and the incidence of deformities in the mentum was quantified. Sediment samples were collected at the same locations where larvae were collected, to quantify the bioavailable fractions of Cu and Zn. The concentrations of Cu in the sediment were similar between the collection sites. However, Zn concentrations varied among sites, being greater in the stretch directly influenced by the input of the organic waste. In total, 2,895 Chironomid larvae were collected. The incidence of deformities in the mentum was above 30% and was correlated with the concentrations of Cu (r = 0.68) and Zn (r = 0.87). This correlation indicates that the municipal waste that is thrown into the citys streams has influenced the occurrence of deformities.(AU)

The effects of heavy metals on the incidence of morphological deformities in Chironomidae (Diptera)

Streams in urban areas are strongly impacted by the input of organic matter and metals, for instance copper (Cu) and zinc (Zn). These metals are essential for the aquatic biota, but when absorbed in excess they are toxic. In Chiro nomidae larvae, the deleterious effects of heavy metals can be ascertained by analyzing the morphological deformities of the larval mentum, a structure of the oral cavity. In this study, we evaluated I) the bioavailability of Cu and Zn in urban stream sediments and II) the relationship between Cu and Zn concentrations and the incidence of deformities in the mentum of Chironomus larvae. Chironomid flies were collected from four locations in two streams at an urban area in southern Brazil. They were identified and the incidence of deformities in the mentum was quantified. Sediment samples were collected at the same locations where larvae were collected, to quantify the bioavailable fractions of Cu and Zn. The concentrations of Cu in the sediment were similar between the collection sites. However, Zn concentrations varied among sites, being greater in the stretch directly influenced by the input of the organic waste. In total, 2,895 Chironomid larvae were collected. The incidence of deformities in the mentum was above 30% and was correlated with the concentrations of Cu (r = 0.68) and Zn (r = 0.87). This correlation indicates that the municipal waste that is thrown into the citys streams has influenced the occurrence of deformities.

Neurodegeneration Induced by Metals in Caenorhabditis elegans.

Metals are a component of a variety of ecosystems and organisms. They can generally be divided into essential and nonessential metals. The essential metals are involved in physiological processes once the deficiency of these metals has been associated with diseases. Although iron, manganese, copper, and zinc are important for life, it has been evidenced that they are also involved in neuronal damage in many neurodegenerative disorders. Nonessential metals, which are metals without physiological functions, are present in trace or higher levels in living organisms. Occupational, environmental, or deliberate exposures to lead, mercury, aluminum, and cadmium are clearly correlated with the increase of toxicity and varied kinds of pathological situations. Actually, the field of neurotoxicology needs to satisfy two opposing demands: the testing of a growing list of chemicals and resource limitations and ethical concerns associated with testing using traditional mammalian species. Toxicological assays using alternative animal models may relieve some of this pressure by allowing testing of more compounds while reducing expenses and using fewer mammals. The nervous system is by far the more complex system in C. elegans. Almost a third of their cells are neurons (302 neurons versus 959 cells in adult hermaphrodite). It initially underwent extensive development as a model organism in order to study the nervous system, and its neuronal lineage and the complete wiring diagram of its nervous system are stereotyped and fully described. The neurotransmission systems are phylogenetically conserved from nematodes to vertebrates, which allows for findings from C. elegans to be extrapolated and further confirmed in vertebrate systems. Different strains of C. elegans offer a new perspective on neurodegenerative processes. Some genes have been found to be related to neurodegeneration induced by metals. Studying these interactions may be an effective tool to slow neuronal loss and deterioration.

Zinc poisoning associated with separation anxiety in an Argentinean bulldog.

Separation anxiety in dogs is a complex behavioral syndrome produced by many causes. A hunter 4y-old male Argentinean Bulldog had dental disturbances and gastrointestinal and cutaneous symptoms due to high plasma zinc and low copper and calcium plasma concentration. His behavior made him bite galvanized wire fences in his cage and bunk that contained his food, both of a Zn-containing material. Specific treatment resulted in complete recovery.

delta-Aminolevulinate dehydratase inhibition by 2,3-dimercaptopropanol is mediated by chelation of zinc from a site involved in maintaining cysteinyl residues in a reduced state.

The mechanisms underlying mouse delta-aminolevulinate dehydratase (ALA-D) inhibition by a chelating agent used in the treatment of heavy metal poisoning, 2,3-dimercaptopropanol (British Anti-Lewisite), were investigated. ALA-D inhibition by 2,3-dimercaptopropanol was totally reversed by 25-100 microM Zn2+, indicating that inhibition was due to chelation of zinc by 2,3-dimercaptopropanol. Our data suggested that zinc bound to a labile site (displaced by 25-40 microM EDTA or 500 microM 2,3-dimercaptopropanol) is involved in maintaining the sulfhydryl groups of ALA-D in a reduced state (essential for enzyme activity), since inhibition by these compounds was reversed by 10 mM dithiotreitol (a reducing agent). On the other hand, 10 mM dithiotreitol did not reverse ALA-D inhibition by a higher concentration of EDTA (100 microM). Accordingly, 2,3-dimercaptopropanol appears to inhibit ALA-D through a mechanism similar to that of low EDTA concentrations. Neither oxidized 2,3-dimercaptopropanol nor reactive oxygen species appeared to contribute for ALA-D inhibition by reduced 2,3-dimercaptopropanol. Taken together, these results suggest that 2,3-dimercaptopropanol inhibits ALA-D by chelating Zn2+ from a labile site that is involved in maintaining enzyme sulfhydryl groups in a reduced state. This site is compatible with the ZnB or Zn beta previously described in mammalian and bacterial ALA-D.

Intoxicação por zinco / Zinc poisoning

Neste trabalho, a autora faz uma revisão bibliográfica sobre intoxicação por zinco, um metal amplamente presente em diversos ambientes industriais. O zinco tem efeitos tópicos e sistêmicos sobre o organismo humano, sendo que, muitas vezes, estes efeitos não são correlacionados à este metal, pois nos ambientes industriais, geralmente há uma associação de metais e outras substâncias. Neste trabalho são citados: a composição química, população exposta, efeitos tóxicos sobre o organismo, quadro clínico da intoxicação pelo zinco. Há uma correlação entre a revisão bibliográfica e a amostra de pacientes atendidos no ambulatório de Saúde Ocupacional do Hospital Universitário Antonio Pedro. A autora visa através de revisão bibliográfica fornecer dados à respeito do zinco, seus efeitos correlacionado à saúde do trabalhador, o uso do zinco na indústria, a população exposta, quadro clínico da intoxicação, tratamento e prevenção.

Intoxicación por raticida y status epilepticus / Intoxication with raticide and status epilepticus

La intoxicación por raticidas (Fosfuro de Zinc) es potencialmente letal y cuando existen manifestaciones clínicas del sistema nervioso central, la mortalidad alcanza hasta el 70%de los casos. Se presenta el caso de un preescolar con intoxicación por fosfuro de zinc. La ingestión de este tóxico causó estado epiléptico, cuya evolución fué satisfactoria, con recuperación neurológica completa.

Estudio sobre el mecanismo de accion del zincum metalico / Study about the action mode of the metallic zincum

El objeto de este estudio es presentar la revision documental de un medicamento homeopatico que se ha usado durante doscientos anos. Se trata de um oligoelemento, el zinc, que en los ultimos dieciocho anos ha sido profundamente estudiado en cuanto al aspecto bioquimico, farmacologico y principalmente la accion toxica en el organismo

Estudio sobre el mecanismo de accion del zincum metalico / Study about the action mode of the metallic zincum

El objeto de este estudio es presentar la revision documental de un medicamento homeopatico que se ha usado durante doscientos anos. Se trata de um oligoelemento, el zinc, que en los ultimos dieciocho anos ha sido profundamente estudiado en cuanto al aspecto bioquimico, farmacologico y principalmente la accion toxica en el organismo