RESUMO
Bufo arenarum embryos at the end of their embryonic development were acclimated to cadmium (Cd) by means of a 10-day treatment protocol. Embryos were processed for metallothionein (Mt) isolation and Cd and zinc (Zn) contents were measured. The results showed that: (1) the uptake of Cd in the experimental embryos was 7 microg/g embryo (wet weight) representing a bioaccumulation of Cd 255 times higher than in the maintaining medium; (2) a major Mt-like fraction was Cd-induced 7.8 times that in control embryos; two other protein fractions also bound Cd and Zn but were induced by Cd only about 2 and 1.4 times; (3) the Zn concentration was about 44 microg Zn/g embryo (wet weight) and did not change significantly (p>0.01) in the experimental embryos with respect to controls, but in acclimated embryos the essential metal was released from the Mts. The enhanced Mt synthesis and release of Zn from the native Mts are discussed in relation to the acclimation phenomenon.
RESUMO
An isocratic high-performance liquid chromatography with electrochemical detection (HPLC-ED) method for the determination of total plasma homocysteine [H(e)] has been developed. The electrochemical detection is performed using a glassy-carbon electrode that is not specific for thiol groups. We have tried to solve the problem of specificity focusing our work on chromatographic resolution and have obtained good results without coelution of other thiol compounds or any substances mentioned as common interferences for carbon electrode methods: uric acid, ascorbic acid and salicylates. Thirty samples a day can be assayed for total homocysteine with a lower limit of detection of 2 pmol, and a limit of quantification of 1.0 micromol/l, with a coefficient of variation (C.V.) <20%. For a concentration of total plasma homocysteine of 9.36 micromol/l, the intra- and inter-assay C.V.s were of 3.86% and 5.55% respectively. The analytical recovery achieved in the preparation of the samples ranged from 85.0% to 98.3% and the electrochemical response was linear up to 100 micromol/l.
Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Homocisteína/sangue , Carbono , Eletroquímica/instrumentação , Eletrodos , Humanos , Padrões de Referência , Sensibilidade e EspecificidadeRESUMO
La determinación de los niveles de homocisteína plasmática total se ha convertido en un estudio de gran utilidad debido a que los valores moderadamente elevados de homocisteína circulantes pueden causar aterosclerosis y obstrucción de las arterias coronarias. Se sabe que son varios los factores que causan el aumento de homocisteína plasmática; éstos incluyen afecciones metabólicas hereditarias, estado nutricional y el tratamiento con ciertos fármacos. Los posibles mecanismos por los cuales los niveles elevados de homocisteína causan afecciones vasculares incluyen efectos sobre las plaquetas, los factores de coagulación y el endotelio. Las lesiones ateroscleróticas y la trombosis relacionadas con la hiperhomocisteinemia podrían ser prevenidas con una dieta rica en vitaminas, aunque esto hasta el presente no ha sido comprobado
Assuntos
Homocisteína/metabolismo , Metionina/metabolismo , Doenças Vasculares/enzimologia , Fatores de Risco , Trombose , Vitaminas , Vitaminas/uso terapêuticoRESUMO
Bufo arenarum females were treated daily with 0.5 mg Cd kg(-1) during 10 days to evaluate the uptake of this heavy metal and the induction of metallothionein synthesis in the liver. The liver incorporated 26% of the Cd administered, about 6.5 times higher than the average uptake of the other tissues of B. arenarum. Three protein fractions from the B. arenarum liver bound Cd, and were induced by this xenobiotic up to approx. 24 times above the basal level of these proteins.
RESUMO
Gonadotropin-releasing hormone (GnRH) molecular variants in the brain and pituitary gland of pejerrey, Odontesthes bonariensis (Atheriniformes), were characterized by gradient reverse phase high performance liquid chromatography (RP-HPLC). Eluted fractions were tested in radioimmunoassays with different antisera. The results show that the brain extract contains three forms of GnRH: one is immunologically and chromatographically similar to cIIGnRH (chicken II), and another is similar to sGnRH (salmon). A third GnRH appears to be chromatographic and immunologically different from the nine other known forms of the vertebrate hormone. This is the only variant present in the pituitary gland.
Assuntos
Encéfalo/metabolismo , Hormônio Liberador de Gonadotropina/análogos & derivados , Hormônio Liberador de Gonadotropina/isolamento & purificação , Hipófise/metabolismo , Precursores de Proteínas/metabolismo , Animais , Argentina , Química Encefálica , Cromatografia Líquida de Alta Pressão , Peixes , Hormônio Liberador de Gonadotropina/análise , Hormônio Liberador de Gonadotropina/química , Hormônio Liberador de Gonadotropina/metabolismo , Hipófise/química , Precursores de Proteínas/análise , Precursores de Proteínas/química , Radioimunoensaio , Extratos de Tecidos/químicaRESUMO
The purpose of the present work was to develop a chromatographic system for the separation of five molecular forms of the gonadotropin-releasing hormone (GnRH); mammalian GnRH (mGnRH) (LHRH), salmon GnRH (sGnRH), chicken I GnRH (cIGnRH), chicken II GnRH (cIIGnRH) and lamprey GnRH I (IGnRH-I). By using an ion-exchange HPLC column and isocratic elution, it was possible to separate properly the five peptides in approximately 20 min. The utility of the system in determining the GnRHs forms present in the brain of two species of vertebrates was examined.
Assuntos
Hormônio Liberador de Gonadotropina/isolamento & purificação , Animais , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Hormônio Liberador de Gonadotropina/química , Especificidade da Espécie , Espectrofotometria UltravioletaRESUMO
Molecular variants of GnRH (gonadotropin-releasing hormone) in brain and pituitary extracts of the South American characiforme Prochilodus lineatus were studied using a combination of reverse-phase high-performance liquid chromatography and radioimmunoassay with different antisera. In brain extracts our study revealed that this fish has at least two different types of GnRH: cIIGnRH (chicken II) and sGnRH (salmon), and possibly a third variant of this molecule. In pituitary extracts we could find only two immunoreactive peaks corresponding to sGnRH and the possible third form.