Aplicação da técnica de fluorescência para avaliação de microrganismos visando a construção de biossensores

A identificação rápida e precisa de microrganismos constitui-se em etapa primordial e de extrema importância no diagnóstico de patologias, controle de qualidade na indústria de alimentos e agricultura. Desta forma, é necessário o desenvolvimento de um método que seja rápido, eficaz e de baixo custo. O uso da técnica de fluorescência tem como vantagens: (a) ser de baixo custo quando comparado com outras técnicas não fotônicas; (b) permitir a obtenção dos resultados em poucos segundos; (c) realizar as medidas in situ; (d) nenhuma ou pequena preparação de amostra é necessária e (e) não há geração de resíduos químicos. Nesse sentido, o objetivo deste trabalho foi aplicar a fluorescência para avaliação de microrganismos e, em especial, a ação do peptídeo antimicrobiano (PAM) polycerradin, com intuito de utilizá-lo como bioreceptor na confecção de biossensor. Os espectros de fluorescência para avaliação dos microrganismos puros e sob ação do PAM foram obtidos utilizando um espectrofluorímetro Shimadzu, RF-5301PC, com comprimento de onda de excitação fixo em 280 nm e um intervalo de detecção de 290-550 nm. Após crescimento em ágar, as suspensões microbianas foram preparadas em solução salina conforme orientações do CLSI. O PAM polycerradin foi solubilizado em água destilada esterilizada em uma concentração de 10 mg/mL. Para análise instrumental, foram depositados em uma cubeta 3 ml da suspensão microbiana e 0,5 ml do PAM (espectros foram obtidos em triplicata). A partir da análise dos espectros de emissão foi realizado um estudo comparativo entre a amostra microbiana antes e após a adição do PAM, tendo sido verificado que a intensidade de emissão para diversos microrganismos diminuiu em até 100 vezes após a adição do composto antimicrobianoFil: Perazzoli, Ivan L O. Universidade Federal de Sao Carlos (Brasil)Fil: Serrano, Nadja F G. Universidade Federal de Sao Carlos (Brasil)Fil: Araújo, Moreira. Universidade Federal de Sao Carlos (Brasil)Fil: Fernando, M. Universidade Federal de Sao Carlos (Brasil

Effect of prepartum administration of recombinant bovine somatotropin (rbST) on plasma beta-hydroxybutyrate levels in ewes subjected to subclinical ketosis.

O objetivo deste estudo foi determinar o efeito da rbST pré-parto no perfil de plasma BHB de ovelhas gestantes submetidas a cetose subclínica

A HIF-independent, CD133-mediated mechanism of cisplatin resistance in glioblastoma cells

Purpose Glioblastoma Multiforme (GBM) is the commonest brain tumour in adults. A population of cells, known as cancer stem cells (CSCs), is thought to mediate chemo/radiotherapy resistance. CD133 is a cell surface marker to identify and isolate CSCs. However, its functional significance and the relevant microenvironment in which to study CD133 remain unknown. We examined the influence of hypoxia on CD133 expression and the potential functional significance of CD133 in glioblastoma chemoresistance. Methods Gene expression was analysed by qRT-PCR. siRNA technique was used to downregulate genes and confirmed by flow cytometry. IC50 values was evaluated with the Alamar blue assay. Results CD133 expression was upregulated in hypoxia in 2D and 3D models. There was increased resistance to chemotherapeutics, cisplatin, temozolomide and etoposide, in cells cultured in hypoxia compared to normoxia. siRNA knockdown of either HIF1a or HIF2a resulted in reduced CD133 mRNA expression with HIF2a having a more prolonged effect on CD133 expression. HIF2a downregulation sensitized GBM cells to cisplatin to a greater extent than HIF1a but CD133 knockdown had a much more marked effect on cisplatin sensitisation than knockdown of either of the HIFs suggesting a HIF-independent mechanism of cisplatin resistance mediated via CD133. The same mechanism was not involved in temozolomide resistance since downregulation of HIF1a but not HIF2a or CD133 sensitized GBM cells to temozolomide. Conclusion Knowledge of the mechanisms involved in the novel hypoxia-induced CD133-mediated resistance to cisplatin observed might lead to identification of new strategies that enable more effective use of current therapeutic agents

RENAL EFFECTS OF NIFEDIPINE AND CAPTOPRIL IN PATIENTS WITH ESSENTIAL-HYPERTENSION AND REDUCED RENAL RESERVE

In this study we investigated the short-term effects of calcium channel blockers and angiotensin-converting enzyme inhibitors on renal hemodynamics and the urinary excretion of proteins with different relative mass in subjects with mild to moderate essential hypertension and apparently normal glomerular filtration rate but reduced renal functional reserve. Sixteen subjects underwent the following four treatments: (1) low-protein meal (0.2 g protein/kg body wt), (2) high-protein meal (1.3 g protein/kg body wt), (3) high-protein meal plus oral nifedipine (20 mg), and (4) high-protein meal plus oral captopril (50 mg). Two urine samples were obtained after meals. Blood samples were drawn at the midpoint of each 120-minute urine collection period. Urine and serum were tested for total protein, immunoglobulin G, albumin, alpha(1)-microglobulin, retinol binding protein, and beta(2)-microglobulin. Glomerular filtration rate and renal plasma flow were assessed by iothalamate and p-aminohippuric clearance, respectively. Compared with the high-protein meal alone, nifedipine elicited a dear-cut increase in the urinary excretion of total protein (+60%, P<.01), immunoglobulin G (+58%, P<.01), albumin (+25%, P<.05), retinol binding protein (+47%, P<.05), and beta(2)-microglobulin (+52%, P<.05); captopril decreased the urinary excretion rate of immunoglobulin G (-26%, P<.05), albumin (-22%, P<.05), and beta(2)-microglobulin (-34%, P<.05). The ratio between the clearances of immunoglobulin G and albumin was higher after nifedipine (+21%, P<.01) and unchanged after captopril (-9%, P=NS) compared with the high-protein meal alone. Glomerular filtration rate and renal plasma flow were higher after nifedipine (+10%, P<.05 and +9%, P<.05, respectively) and lower after captopril(-2%, P<.05 and -9%, P=NS, respectively) than after the high-protein meal alone. Thus, single doses of nifedipine, preceding a protein load in the form of a meat meal, raise both glomerular filtration rate and renal plasma flow and increase urinary protein excretion rate. Changes in both glomerular selectivity and tubular reabsorption seem to account for increased proteinuria