Browsing by Issue Date, starting with "1990"
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- Microperfusion studies on the permeability of retinal vessels. A new model demonstrating organic anion transport and a reabsorptive fluid fluxPublication . Murta, JN; Cunha-Vaz, JG; Sabo, CA; Jones, CW; Laski, MEWe developed an experimental model to study the permeability of individual retinal vessels in vitro using microperfusion techniques adapted from kidney tubule studies. The retinal vessels were isolated by freehand dissection and mounted on a microperfusion apparatus. When inulin was perfused luminally, it was diluted to 80.2 +/- 2.3% of its initial concentration. However, no radioactive leak into the bath side was observed, suggesting that the dilution was due to fluid flux from bath to lumen. The dilution of fluorescein (81.9 +/- 3.8%) was in the same range as that of inulin, the reference marker. The extremely low lumen-to-bath fluorescein flux, 0.5 +/- 0.9 X 10(-12) mol/min/mm, increased by 68% when probenecid was added to the perfusate and by 210% when probenecid was placed in the bath. The effect was concentration-dependent. When placed in the bath, fluorescein moved rapidly across the retinal vessel walls, accumulating in the lumen to concentrations 40 times higher than in the bath. This movement from bath to lumen, which was much higher (13.6 +/- 0.3 X 10(-12) mol/min/mm) than the lumen-to-bath fluorescein flux for the same fluorescein concentration, decreased by adding probenecid to the bath. The kinetics of this unidirectional movement of fluorescein were consistent with a saturable active transport process. The fluid flux from bath to lumen across the retinal vessels, which was 6.3 +/- 1.0 nl/min/mm for perfusion rates of 6.6 +/- 0.2 nl/min, was temperature-dependent and was coupled to the fluorescein transport. Fluorescein stimulated the fluid flux by 17% when added to the perfusate and by 60% when added to the bath, and this effect could be reversed by probenecid. Our results showed an active transport of fluorescein in the rabbit retinal vessels coupled with net fluid flux from outside the vessels into the lumen.
- A evolução do conteúdo dos sonhos no luto patológico: a propósito de um caso clínicoPublication . Santos, PA; Pio-Abreu, JL
- Intraventricular neurocytoma: a clinical and pathological study of three cases and review of the literaturePublication . Barbosa, MD; Balsitis, M; Jaspan, T; Lowe, JThree patients with a recently described tumor of neuronal origin, intraventricular neurocytoma, are presented. These tumors occur as intraventricular lesions in young patients, and the prognosis after surgical treatment is favorable. The initial pathological diagnosis of intraventricular neurocytoma may be difficult because of the striking resemblance of these tumors to oligodendroglioma and, to a lesser extent, ependymoma on light microscopic examination. Despite the use of wide-ranging panels of monoclonal antibodies, previous authors have not found any characteristic immunohistochemical staining patterns, but in our three patients, the use of synaptophysin, glial fibrillary acidic protein, and Leu-7 demonstrated staining patterns that may be useful in the diagnosis of this tumor. The monoclonal antibody Ki-67 was used to stain one tumor and showed a low cell proliferation rate. We have reviewed the clinical, radiological, and pathological features of these 3 patients and 17 previously described patients in an attempt to determine the important diagnostic features of intraventricular neurocytoma. Intraventricular neurocytoma should be considered in any young patient with symptoms of raised intracranial pressure and radiological evidence of an intraventricular lesion. Pathological diagnosis requires the use of electron microscopy to show features of neuronal differentiation; however, immunohistochemical demonstration of a neuronal phenotype is also a useful adjunct to diagnosis. Failure to use specialized techniques for pathological diagnosis will lead to misdiagnosis of these lesions as oligodendrogliomas, as was the initial diagnosis in 2 of our patients before review.
- Allergic contact dermatitis from Nicotiana tabacumPublication . Gonçalo, Margarida; Couto, J; Gonçalo, S
- Articular lymphoscintigraphy in human knees using radiolabeled dextranPublication . Albuquerque, M; Pedroso de Lima, J