Glomerular filtration rate measured by 51Cr-EDTA clearance: evaluation of captopril-induced changes in hypertensive patients with and without renal artery stenosis

INTRODUCTION: Renal artery stenosis can lead to renovascular hypertension; however, the detection of stenosis alone does not guarantee the presence of renovascular hypertension. Renovascular hypertension depends on activation of the renin-angiotensin system, which can be detected by functional tests such as captopril renal scintigraphy. A method that allows direct measurement of the baseline and post-captopril glomerular filtration rate using chromium-51 labeled ethylenediamine tetraacetic acid (51Cr-EDTA) could add valuable information to the investigation of hypertensive patients with renal artery stenosis. The purposes of this study were to create a protocol to measure the baseline and post-captopril glomerular filtration rate using 51Cr-EDTA, and to verify whether changes in the glomerular filtration rate permit differentiation between hypertensive patients with and without renal artery stenosis. METHODS: This prospective study included 41 consecutive patients with poorly controlled severe hypertension. All patients had undergone a radiological investigation of renal artery stenosis within the month prior to their inclusion. The patients were divided into two groups: patients with (n=21) and without renal artery stenosis, (n=20). In vitro glomerular filtration rate analysis (51Cr-EDTA) and 99mTc-DMSA scintigraphy were performed before and after captopril administration in all patients. RESULTS: The mean baseline glomerular filtration rate was 48.6±21.8 ml/kg/1.73 m² in the group wuth renal artery stenosis, which was significantly lower than the GFR of 65.1±28.7 ml/kg/1.73m² in the group without renal artery stenosis (p=0.04). Captopril induced a significant reduction of the glomerular filtration rate in the group with renal artery stenosis (to 32.6±14.8 ml/kg/1.73m², p=0.001) and an insignificant change in the group without RAS (to 62.2±23.6 ml/kg/1.73m², p=0.68). Scintigraphy with technetium-99m dimercapto-succinic acid (DMSA) did...

Consideracoes sobre a biodisponibilidade do ferro dos alimentos / Considerations regarding eron biovailability

Neste artigo se apresenta uma revisao documentada com mais de 60 referencias sobre o tema da disponibilidade do ferro. O trabalho oferece uma secao dedicada a terminologia empregada, enfatizando a conveniencia do termo "biodisponibilidade ou disponibilidade biológica de nutrientes" que tem certa discrepancia. Depois estuda os factores extrínsecos ou fisiológicos e os fatores intrínsecos ou dietéticos que afectan a disponibilidade do ferro. A continuacao se apresenta uma discussao sobre a biodisponibilidade do ferro dos alimentos de origem animal e vegetal, dos alimentos fortificados com sais de ferro e dos alimentos com ferro provenientes de contaminacao. O artigo refere como pesquisadores compararam métodos "in vitro" e "in vivo" para determinar a biodisponibilidade do ferro, concluindo que ambos os métodos devem ser associados. Para finalizar explica que apesar das mudancas ocurridas em diversos ambitos, novas questoes surgen sobre a importancia do ferro dos alimentos na solucao do problema da deficiencia desde mineral