Determination of methylmercury and inorganic mercury in human hair samples of individuals from Colombian gold mining regions by double spiking isotope dilution and GC-ICP-MS.

With the aim to distinguish between routes of exposition to mercury (Hg) in artisanal and small-scale gold mining (ASGM) communities and to distinguish between Hg contamination sources, Hg species composition should be performed in human biomarkers. In this work, Hg species-specific determination were determined in human hair samples (N = 96), mostly non-directly occupied in ASGM tasks, from the six most relevant gold mining Colombian regions. Therefore, MeHg, Hg(II) and THg concentrations were simultaneously determined by double spiking species-specific isotope dilution mass spectrometry (IDMS) and GC-ICP-MS. Only 16.67% of participants were involved at some point in AGSM works and fish consumption ranged from 3 to 7 times/week, which is between medium and high intake levels. The median concentration of THg obtained from all samples is higher than the reference dose weekly acceptable of MeHg intake established by the EPA (1 ppm), whereas a 25% were more than 4 times higher than the WHO level (2.2 µg Hg g-1). Median THg value of individuals consuming fish 5-7 times per week was significantly higher (p < 0.05) than those of the other consuming groups (12.5 µg Hg g-1). Most of the samples presented a % of MeHg relative to THg higher than 80%. The average % of Hg(II)/THg was 11% and only 10 individuals presented a Hg(II) content over 30%. No significant differences (p > 0.05) were found when the amount of Hg(II) was compared between people involved in AGSM task and people not involved. Interestingly, significant differences among the evaluated groups where found when the percentage of the Hg(II)/THg ratio of these groups were compared. In fact, people involved in AGSM tasks showed 1.7 times higher Hg(II)/THg vs. inhabitants uninvolved. This suggest that Hg(II) determination by IDMS-GC-ICP-MS could be a good proxy for evaluating Hg(II) adsorption by direct exposure to mercury vapors onto hair.

Bacterial diversity patterns of the intertidal biofilm in urban beaches of Río de la Plata.

Intertidal benthic ecosystems in estuaries are productive sites where microbial processes play critical roles in nutrients mineralization, primary production and trophic web. In this groundwork study we analyzed the bacterial community of intertidal biofilms from Río de la Plata beaches with different anthropogenic impacts. Several environmental parameters were measured and bacterial assemblages were analyzed by 16S-rDNA pyrosequencing. The average OTU found per sample was 527.3±122.5, showing similar richness and diversity among them. However, sites having the highest and lowest salinity displayed higher bacterial diversity. Assemblages from a site nearby an oil refinery, showing the lowest salinity and oxygen concentration, were clearly distinct from the rest. The weight of this splitting relied on OTUs belonging to Thauera, known by its ability to metabolize aromatic compounds. Our results suggest that intertidal bacterial assemblages would be structured by major estuarine variables such as salinity, and that anthropogenic-induced environmental parameters might also be relevant.

Hacia un Web accesible / Towards an Accessible Web

Se abordan los conceptos de accesibilidad y su importancia. Se detallan las principales técnicas para lograr un sitio Web accesible, un conocimiento imprescindible para el diseño metodológico correcto y la implementación de los sitios Web.

The concepts of availability, as well as their importance, are analyzed. A detailed description is made of the main techniques to achieve an accessible Web site, an indispensable knowledge for the correct methodological design and the implementation of the Websites.

Steroid metabolism in vitro during final oocyte maturation in white croaker Micropogonias furnieri (Pisces: Sciaenidae).

Final oocyte maturation (FOM) is a process involving a complex set of genetical, biochemical, and morphological mechanisms. FOM involves the shift of a post-vitellogenic follicle to a pre-ovulated oocyte, which is necessary for fertilization by spermatozoan to occur. This process is regulated by a maturation-inducing steroid (MIS) at the follicular level. In other species of scienids fish the MIS, a hydroxilated derivatives of progestagen 17, 20beta, 21-trihydroxy-4-pregnen-3-one (20beta-S), was identified. Although Micropogonias furnieri is the second fishery resource of Uruguay, basic knowledge about its endocrine process is very scarce. The aim of this work was to investigate what steroids are synthesized in vitro by the oocyte follicle of M. furnieri during the maturation process. Fragments of ovary (1 g) in three stages: post-vitellogenic (PV), maturing (Mtg), and mature (M) were incubated with 1 microg x g(-1) of tritiated progesterone (P) at 30, 60, and 180 min. After extraction with ethanol and dichloromethane, steroid metabolites were purified by TLC and rpHPLC. Two progesterone derivatives with identical chromatographic properties of 20beta-S and 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) were purified. In other Teleost fish these steroids are biologically active as MIS. The 17,20beta-P was clearly detected in Mtg and M stages and confirmed by enzymatic oxidation with enzyme 20beta-HSD. The 20beta-S was strongly detected in all Mtg oocytes. The results do not corroborate 20beta-S as a major hormone synthesized in the ovary in FOM as occurs in other scienid fish. A differential steroid synthesis in the advanced oocyte stages suggests that the 20beta-S is acting as a MIS in M. furnieri.

Induction of oocyte maturation in the white croaker Micropogonias furnieri (Pisces: Sciaenidae) by human chorionic gonadotropin.

The present work aimed to identify the best doses of human chorionic gonadotropin (hCG) needed to induce oocyte maturation of Micropogonias furnieri and to characterize ovarian dynamics during the periovulatory period. Adult M. furnieri females with fully developed ovaries were injected intraperitoneally with four different doses of hCG. The gonadotropin response was succeeded by analyzing morphologically gonadal biopsies and following the postinjection changes in follicle diameter. Oocyte maturation was induced by three doses used: 100, 300, and 500 IU of hCG kg bw-1, and was reached 48 h after treatment with 300 and 500 IU of hCG kg bw-1, and 72 h after treatment with 100 IU of hCG kg bw-1. Concerning ovarian dynamics, only 100 and 300 IU of hCG kg bw-1 mimicked the natural ones which have a synchronic group maturation. In conclusion, the dose mimicking natural ovarian dynamics and inducing oocyte maturation more quickly is 300 IU of hCG kg bw-1.

Steroid metabolism in vitro during final oocyte maturation in white croaker Micropogonias furnieri (Pisces: Scianidae)

A maturação ovocitária final (FOM) é um processo complexo que envolve mecanismos genéticos, bioquímicos e morfológicos que conduzem à transformação de um ovócito pós-vitelogênico em um ovócito apto a ser fertilizado. Esse processo está regulado pelo hormônio esteróide indutor da maturação ovocitária final (MIS), o qual é sintetizado no folículo. Em outras espécies de Sciaenidae, o MIS foi identificado como um derivado hidroxilado da progesterona 17, 20beta, 21-trihydroxy-4-pregnen-3-one (20beta-S). Micropogonias furnieri é um recurso superexplorado na costa uruguaia, contudo, seus processos endócrinos são pouco conhecidos. O objetivo deste trabalho foi pesquisar quais esteróides são sintetizados in vitro pelos folículos em maturação de M. furnieri. Fragmentos de ovários (1 g) foram incubados em três estágios diferentes: pós-vitelogênese (PV), em maturação (Mtg) e maduros (M) com 1 mg/g de progesterona tritriada (P) durante 30, 60 e 180 min. Depois da extração dos esteróides com etanol e diclorometano, esses foram purificados e identificados utilizando-se TLC, rpHPLC e oxidação enzimática. Foram identificados dois derivados de progesterona com idênticas propriedades cromatográficas ao 20beta-S e 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P), os quais, em outras espécies de peixes, apresentam atividade biológica como o MIS. A 17,20beta-P foi observada claramente nos estágios Mtg e M e confirmada pela oxidação com a enzima 20beta-HSD. A 20beta-S foi claramente observada nos ovários em maturação (Mtg). Os resultados não permitiram confirmar que 20beta-S é o hormônio mais sintetizado nos estágios estudados, como ocorre em outras espécies de ciaenídeos, mas a presença de uma síntese diferencial no estágio de maturação sugere que 20beta-S esteja atuando como o MIS em M. furnieri.

Induction of oocyte maturation in the white croaker Micropogonias furnieri (Pisces: Sciaenidae) by human chorionic gonadotropin

O presente estudo teve por objetivo identificar as melhores doses de gonadotrofina cariônica humana (hCG) necessárias para maturação de oócitos de Micropogonias furnieri e caracterizar a dinâmica do ovário ao longo do período pré-ovulatório. Fêmeas adultas de M. furnieri, com ovários completamente desenvolvidos, receberam intraperitonealmente quatro doses diferentes de hCG. A resposta à gonadotrofina foi acompanhada de análise morfológica de biópsias gonadais e mudanças no diâmetro dos folículos após estimulação. A maturação dos oócitos foi induzida por três doses de hCG kg bwû1, 100, 300 e 500 UI. A maturação dos oócitos foi atingida após 48 h de tratamento com 300 e 500 UI de hCG kg bwû1 e após 72 h de tratamento com 100 UI de hCG kg bwû1. Em relação à dinâmica do ovário, apenas os tratamentos com 100 e 300 UI de hCG kg bwû1 reproduziram sua dinâmica natural, apresentando maturação em grupo sincronizada. Esses resultados permitem concluir que a dose capaz de reproduzir a dinâmica do ovário e induzir maturação dos oócitos em curtos períodos é de 300 UI de hCG kg bwû1.

Steroid metabolism in vitro during final oocyte maturation in white croaker Micropogonias furnieri (Pisces: Scianidae)

Final oocyte maturation (FOM) is a process involving a complex set of genetical, biochemical, and morphological mechanisms. FOM involves the shift of a post-vitellogenic follicle to a pre-ovulated oocyte, which is necessary for fertilization by spermatozoan to occur. This process is regulated by a maturation-inducing steroid (MIS) at the follicular level. In other species of scienids fish the MIS, a hydroxilated derivatives of progestagen 17, 20beta, 21-trihydroxy-4-pregnen-3-one (20beta-S), was identified. Although Micropogonias furnieri is the second fishery resource of Uruguay, basic knowledge about its endocrine process is very scarce. The aim of this work was to investigate what steroids are synthesized in vitro by the oocyte follicle of M. furnieri during the maturation process. Fragments of ovary (1 g) in three stages: post-vitellogenic (PV), maturing (Mtg), and mature (M) were incubated with 1 mug.g-1 of tritiated progesterone (P) at 30, 60, and 180 min. After extraction with ethanol and dichloromethane, steroid metabolites were purified by TLC and rpHPLC. Two progesterone derivatives with identical chromatographic properties of 20beta-S and 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P) were purified. In other Teleost fish these steroids are biologically activ as MIS. The 17,20beta-P was clearly detected in Mtg and M stages and confirmed by enzymatic oxidation with enzyme 20beta-HSD. The 20beta-S was strongly detected in all Mtg oocytes. The results do not corroborate 20beta-S as a major hormone synthesized in the ovary in FOM as occurs in other scienid fish. A differential steroid synthesis in the advanced oocyte stages suggests that the 20beta-S is acting as a MIS in M. furnieri.

A maturação ovocitária final (FOM) é um processo complexo que envolve mecanismos genéticos, bioquímicos e morfológicos que conduzem à transformação de um ovócito pós-vitelogênico em um ovócito apto a ser fertilizado. Esse processo está regulado pelo hormônio esteróide indutor da maturação ovocitária final (MIS), o qual é sintetizado no folículo. Em outras espécies de Sciaenidae, o MIS foi identificado como um derivado hidroxilado da progesterona 17, 20beta, 21-trihydroxy-4-pregnen-3-one (20beta-S). Micropogonias furnieri é um recurso superexplorado na costa uruguaia, contudo, seus processos endócrinos são pouco conhecidos. O objetivo deste trabalho foi pesquisar quais esteróides são sintetizados in vitro pelos folículos em maturação de M. furnieri. Fragmentos de ovários (1 g) foram incubados em três estágios diferentes: pós-vitelogênese (PV), em maturação (Mtg) e maduros (M) com 1 mig/g de progesterona tritriada (P) durante 30, 60 e 180 min. Depois da extração dos esteróides com etanol e diclorometano, esses foram purificados e identificados utilizando-se TLC, rpHPLC e oxidação enzimática. Foram identificados dois derivados de progesterona com idênticas propriedades cromatográficas ao 20beta-S e 17,20beta-dihydroxy-4-pregnen-3-one (17,20beta-P), os quais, em outras espécies de peixes, apresentam atividade biológica como o MIS. A 17,20beta-P foi observada claramente nos estágios Mtg e M e confirmada pela oxidação com a enzima 20beta-HSD. A 20beta-S foi claramente observada nos ovários em maturação (Mtg). Os resultados não permitiram confirmar que 20beta-S é o hormônio mais sintetizado nos estágios estudados, como ocorre em outras espécies de ciaenídeos, mas a presença de uma síntese diferencial no estágio de maturação sugere que 20beta-S esteja atuando como o MIS em M. furnieri.

Induction of oocyte maturation in the white croaker Micropogonias furnieri (Pisces: Sciaenidae) by human chorionic gonadotropin

The present work aimed to identify the best doses of human chorionic gonadotropin (hCG) needed to induce oocyte maturation of Micropogonias furnieri and to characterize ovarian dynamics during the periovulatory period. Adult M. furnieri females with fully developed ovaries were injected intraperitoneally with four different doses of hCG. The gonadotropin response was suceeded by analyzing morphologically gonadal biopsies and following the postinjection changes in follicle diameter. Oocyte maturation was induced by three doses used: 100, 300, and 500 IU of hCG kg bw-1, and was reached 48 h after treatment with 300 and 500 IU of hCG kg bw-1, and 72 h after treatment with 100 IU of hCG kg bw-1. Concerning ovarian dynamics, only 100 and 300 IU of hCG kg bw-1 mimicked the natural ones which have a synchronic group maturation. In conclusion, the dose mimicking natural ovarian dynamics and inducing oocyte maturation more quickly is 300 IU of hCG kg bw-1.

O presente estudo teve por objetivo identificar as melhores doses de gonadotrofina cariônica humana (hCG) necessárias para maturação de oócitos de Micropogonias furnieri e caracterizar a dinâmica do ovário ao longo do período pré-ovulatório. Fêmeas adultas de M. furnieri, com ovários completamente desenvolvidos, receberam intraperitonealmente quatro doses diferentes de hCG. A resposta à gonadotrofina foi acompanhada de análise morfológica de biópsias gonadais e mudanças no diâmetro dos folículos após estimulação. A maturação dos oócitos foi induzida por três doses de hCG kg bw-1, 100, 300 e 500 UI. A maturação dos oócitos foi atingida após 48 h de tratamento com 300 e 500 UI de hCG kg bw-1 e após 72 h de tratamento com 100 UI de hCG kg bw-1. Em relação à dinâmica do ovário, apenas os tratamentos com 100 e 300 UI de hCG kg bw-1 reproduziram sua dinâmica natural, apresentando maturação em grupo sincronizada. Esses resultados permitem concluir que a dose capaz de reproduzir a dinâmica do ovário e induzir maturação dos oócitos em curtos períodos é de 300 UI de hCG kg bw-1.

[Effect of strontium on bone metabolism in hemodialysis patients]. / Efecto del estroncio sobre el metabolismo óseo en pacientes en hemodiálisis.

The objective of this study was to assess the relationship between the bone strontium content and bone histomorphometric parameters in bone biopsies from patients with chronic renal failure undergoing hemodialysis. The study was carried out in 74 illiac crest bone biopsies from patients with renal osteodystrophy from different worldwide regions (Argentina, Portugal and Spain). They were underwent to histological and histomorphometric evaluation. The bone strontium/calcium ratio was measured by quadrupole inductively coupled plasma-mass spectrometry. The samples were classified into groups according to histological criteria: hyperparathyroidism (HP), mixed (MX), osteomalacia (OM) and adynamic bone disease (ABD). Serum PTH and alkaline phosphatase before biopsy were available in most of the patients. No correlation was found between the different histomorphometric parameters and the Sr/Ca ratio. The one way ANOVA test showed statistical differences in the Sr/Ca ratio of the different histological forms (HP: 0.58 +/- 0.39; MX: 1.16 +/- 0.74; OM: 1.10 +/- 0.46; ABD: 0.91 +/- 0.40 microgram Sr/mg Ca; p < 0.003). The post-Hoc analysis showed differences between HP and MX. The biopsies having greater or equal values than 1.4 micrograms Sr/mg Ca showed higher levels of bone formation histomorphometric parameters and serum alkaline phosphatase (395 +/- 519 vs 1,022 +/- 989 UI/L, p < 0.05). Although it has been found that the biopsies with higher bone strontium had higher levels of osteoid tissue (characteristic of osteomalacia), the hypothesis of strontium-induced osteomalacia could not be demonstrated.