RESUMO
Background: Suicide is a significant public health problem influenced by various risk factors, including dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis. Zinc (Zn), essential for pituitary function in hormone synthesis and release, has been linked to suicide, with studies noting reduced serum levels and altered brain transport mechanisms. Despite Zn's crucial role in pituitary function and its involvement in suicidal behavior, information on pituitary Zn in suicide is scarce. Tumor cells modify Zn dynamics in tissues, and a previous report suggests microadenomas in the anterior pituitary as a risk factor for suicide. Methods: Histopathological analysis with hematoxylin-eosin stain and histochemical techniques to assess Zn homeostasis were carried out on anterior pituitary postmortem samples from 14 suicide completers and 9 non-suicidal cases. Results: Pituitary microadenomas were identified in 35% of suicide cases and none in the non-suicidal cases. Furthermore, compartmentalized Zn (detected via dithizone reactivity), but not free Zn levels (detected via zinquin reactivity), was lower in the suicide cases compared to the non-suicidal group. Conclusion: This is the first report of a potential association between disrupted Zn homeostasis and microadenomas in the anterior pituitary as a feature in suicide and provides critical insights for future neuroendocrine Zn-related research.
RESUMO
Mercury (Hg) is a toxic metal frequently used in illegal and artisanal extraction of gold and silver which makes it a cause of environmental poisoning. Since biosorption of other heavy metals has been reported for several Lysinibacillus sphaericus strains, this study investigates Hg removal. Three L. sphaericus strains previously reported as metal tolerant (CBAM5, Ot4b31, and III(3)7) were assessed with mercury chloride (HgCl2). Bacteria were characterized by scanning electron microscopy coupled with energy dispersive spectroscopy (EDS-SEM). Sorption was evaluated in live and dead bacterial biomass by free and immobilized cells assays. Hg quantification was achieved through spectrophotometry at 508 nm by reaction of Hg supernatants with dithizone prepared in Triton X-114 and by graphite furnace atomic absorption spectroscopy (GF-AAS). Bacteria grew up to 60 ppm of HgCl2. Non-immobilized dead cell mixture of strains III(3)7 and Ot4b31 showed a maximum sorption efficiency of 28.4 µg Hg/mg bacteria during the first 5 min of contact with HgCl2, removing over 95% of Hg. This process was escalated in a semi-batch bubbling fluidized bed reactor (BFB) using rice husk as the immobilization matrix leading to a similar level of efficiency. EDS-SEM analysis showed that all strains can adsorb Hg as particles of nanometric scale that can be related to the presence of S-layer metal binding proteins as shown in previous studies. These results suggest that L. sphaericus could be used as a novel biological method of mercury removal from polluted wastewater.
RESUMO
El análisis químico día a día se acerca más a la automatización, buscando satisfacer las necesidades actuales de resultados rápidos y confiables. Los sistemas de análisis en flujo (FIA - Flow Injection Analysis) son una de las formas de aproximarse a la automatización. En este artículo se presentan los pasos necesarios para implementar una metodología FIA, para la determinación de Pb(II) en agua, partiendo de la revisión de los procedimientos clásicos y describiendo detalladamente los pasos necesarios para implementar la técnica de análisis en flujo. El trabajo produjo un método de análisis de Pb en agua que usa ditizona disuelta en isopropanol (agente cromogénico), en presencia de bromuro de cetiltrimetil amonio (CTAB), para solubilizar en agua el complejo, cuyas características más sobresalientes fueron: volumen de inyección de muestra de 81,7 µL, velocidad de flujo de 8,0 mL/min, tiempo de toma de espectros 1,4 s e intervalo lineal de 1,0 a 40 mg L-1.
Chemical analysis has evolved towards automation to satisfy the current requirements: fast analysis and certainty in the results. Flow injection analysis (FIA) is a way to reach automation. This work presents the necessary steps to obtain an optimized FIA methodology for the determination of Pb(II) in water by classic methods. The result was a FIA method to determinate Pb with dithizone (chromogenic agent) dissolved in iso-propyl alcohol, using cethyltrimethylammonium bromide (CTAB) to solubilize the complex. The main characteristics of the method were: injection sample volume 81.7 µL, flow 8.0 mL/min, spectra acquisition time 1.4 s and linear range 1 to 40 mg L-1.
Cada dia, a análise química é mais cerca da automatização com o fim de satisfazer as necessidades atuais de resultados rápidos e confiáveis. Os sistemas de análise em fluxo (FIA - Flow Inyection Analysis) são uma das formas de aproximação à automatização. Este artigo apresenta os passos necessários para implementar uma metodologia FIA para a determinação de Pb(II) em água, partindo da revisão dos procedimentos clássicos e descrevendo detalhadamente os passos necessários para implementar a técnica de análise em fluxo. Os resultado são um método de análise de Pb em água que usa ditizona dissolvida em isopropanol (agente cromogénico) na presença de bromuro de cetiltrimetil amônio (CTAB), usado para solubilizar o complexo em água. As características principais do método foram: volume de injeção de amostra de 81,7 µL, velocidade de fluxo de 8,0 mL min-1, tempo de aquisição de espectros de 1,4 s e intervalo linear de 0.9 a 40 mg L-1.