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  • 1
    Electronic Resource
    Electronic Resource
    UPTAKE OF GLUCOSE ANALOGUES BY RAT BRAIN CORTEX SLICES: A KINETIC ANALYSIS BASED UPON A MODEL (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 27 (1976), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— In slice preparations the exchange of dissolved substances between cells and incubation medium is delayed by diffusion through the extracellular space. The delay may seriously interfere with the study of membrane transport in terms of unidirectional fluxes across the cell membranes. A three-compartment serial model has been developed to describe exchange between slice and incubation medium. By aid of this model it is shown that the diffusion delay prevents determination of unidirectional fluxes for the two non-metabolizable glucose analogues 3-O-methylglucose and α-methyl-glucosidc. The membrane transport of the slowly transported α-methylglucoside can however be examined by aid of the model whereas the transport of 3-O-methylglucose is so rapid that it can not be examined with respect to Vmax Km and Kr. An attempt to determine these parameters will result in falsely large values which reflect extracellular diffusion and not membrane transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1976.tb12254.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    UPTAKE OF GLUCOSE ANALOGUES BY RAT BRAIN CORTEX SLICES: Na+-INDEPENDENT MEMBRANE TRANSPORT (1976)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 27 (1976), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— The glucose analogues 3-O-methyl-D-glucose and α-methyl-D-glucoside were not metabolized in brain tissue.The uptake of these two sugars into the intracellular compartment of brain cortex slices was investigated using media with normal and low Na+ concentration (replacement of all NaCl with choline Cl). The cellular transport was not Na+-dependent. The transport mechanism clearly distinguished between the two sugars in both normal and low Na+ media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1976.tb12255.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    UPTAKE OF GLUCOSE ANALOGUES BY RAT BRAIN CORTEX SLICES: MEMBRANE TRANSPORT VERSUS METABOLISM OF 2-DEOXY-d-GLUCOSE (1977)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 29 (1977), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract— —The uptake of the glucose analogue 2-deoxy-d-glucose by rat brain cortex slices was studied in order to compare the rate of membrane transport with the rate of phosphorylation in the concentration range 5–12 mM-glucose plus 0.5–15 mM-2-deoxy-glucose. The comparison was carried out by fitting a model of the brain slice to uptake data and by determination of 2-deoxy-glucose and 2-deoxy-glucose-6-phosphate by ion exchange chromatography.The rate of membrane transport exceeded the rate of phosphorylation by at least one order of magnitude. The membrane transport was so rapid that the extracellular diffusion became rate limiting for the uptake. The membrane transport could therefore only be determined as a minimum value and it was not possible to determine unidirectional flux across the cell membranes (initial rate). Accordingly, characterization of the membrane tranport with respect to maximal transport rate and affinity was not possible. The phosphorylation reaction, however, was so slow that it was accessible for exact determination and only the phosphorylation reaction was responsible for the fact that the cellular uptake of 2-deoxy-glucose was of the Michaelis-Menten type, thus emphasizing the importance of dissociation between membrane transport and metabolism when transport is studied of a substance which can undergo metabolism.The data indicate that glucose transport across glial and neuronal membranes is not rate limiting for glucose metabolism of brain tissue in vitro.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1977.tb09610.x
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  • 4
    Electronic Resource
    Electronic Resource
    Fluorescein and fluorescein glucuronide in the vitreous body of diabetic patients (1987)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 225 (1987), S. 173-176 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fluorescein (F) and fluorescein glucuronide (FG) were determined in the vitreous of four diabetic patients by a double-filter slit-lamp fluorophtometric technique. Determinations were performed 60–80 min after i.v. injection of fluorescein. F and FG were also determined in plasma ultrafiltrate 5, 15, 30, 60 and 120 min after injection by high-pressure liquid chromatography. The concentration of FG in the vitreous was 3 times that of F. After correction for plasma concentrations of FG higher than those of F, the penetration index of FG through the blood-retinal barrier was found to be twice the penetration index of F. This is not what would be expected if passive transport alone were involved. Accordingly, it is suggested that active transport mechanisms contribute to the movement of F and FG across the blood-retinal barrier.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02175445
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  • 5
    Electronic Resource
    Electronic Resource
    Effect of antihypertensive treatment on blood-retinal barrier permeability to fluorescein in hypertensive Type 1 (insulin-dependent) diabetic patients with background retinopathy (1989)
    Springer
    Diabetologia 32 (1989), S. 440-444 
    Details
    ISSN: 1432-0428
    Keywords: Arterial blood pressure ; antihypertensive treatment ; diabetic retinopathy ; diabetic nephropathy ; Type 1 (insulin-dependent) diabetes ; vitreous fluorometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effect of antihypertensive treatment on blood-retinal barrier leakage of fluorescein in background retinopathy was studied in nine hypertensive Type 1 (insulin-dependent) diabetic patients suffering from nephropathy. The patients were investigated before and after 7 (3 to 13) months of treatment with captopril (n=8; 25 to 100 mg daily) and a diuretic, either frusemide (n=4; 80 to 200 mg daily) or bendrofluazide (n=2; 2.5 mg daily). Retinal function was assessed by fundus photography, fluorescein angiography, vitreous fluorometry, and renal function by glomerular filtration rate, and albuminuria. The antihypertensive treatment induced a significant reduction (p〈0.05) in: blood pressure from 152/97±14/8 mmHg to 134/82±11/6 mmHg; blood-retinal barrier leakage of fluorescein from 2.4 ±1.1 to 1.4±0.5·10−7 cm/second; albuminuria from 1391 (range: 168–4852) μg/min to 793 (range: 35–2081) ug/min. Glomerular filtration rate declined from 88±15 to 78±23 ml·min−1·1.73 m2 (0.05〈p〈0.10). The metabolic control of the patients as reflected by their blood glucose and HbA1c levels remained stable during the study. Our study suggests that systemic blood pressure elevation contributes to the abnormal blood-retinal barrier permeability to fluorescein characteristically found in diabetic background retinopathy and that this abnormality can be reversed during antihypertensive treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00271264
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  • 6
    Electronic Resource
    Electronic Resource
    Uptake of inulin by cells in rat brain cortex (1977)
    Springer
    Experimental brain research 28 (1977), S. 37-50 
    Details
    ISSN: 1432-1106
    Keywords: Brain cortex slices ; Membrane transport of macromolecules ; Inulin space
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Light and electron microscope autoradiography indicated that 3H-labelled inulin was taken up by neurons and glia cells of rat brain cortex in vitro. The mechanism, by which inulin passed the cell membranes, was studied by comparing the transport of inulin (molecular weight 5000) with the transport of dextran (molecular weight 75000). The half-time for the cellular in- and efflux for the two molecules was the same although their diffusion coefficients differed by a factor of 4–5. The transport mechanism was therefore interpreted as bulk transport, and vesicular transport is suggested. Efflux of inulin from brain cortex exposed to inulin in vivo indicated that cellular uptake of inulin also occured in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00237084
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  • 7
    Electronic Resource
    Electronic Resource
    Calculation of the permeability of the blood-retinal barrier to fluorescein (1985)
    Springer
    Graefe's archive for clinical and experimental ophthalmology 222 (1985), S. 173-176 
    Details
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A method is presented, for calculation of the permeability of the blood-retinal barrier to fluorescein which is based upon stimultaneous determination of the free fluorescein concentration in plasma and the fluorescein concentration profile in the vitreous body. By aid of a simplified mathematical model of the eye the blood-retinal barrier permeability is calculated automatically on a computer from corresponding values of the fluorescein concentration in plasma and in the vitreous body. The present method eliminates some of the factors of uncertainty, which have been present in earlier applied fluorophotometric methods, thus contributing to increasing the exactness of the fluorophotometric method for the estimation of the permeability of the blood-retinal barrier to fluorescein. Apart from the permeability of the barrier, the diffusion coefficient for fluorescein in the vitreous body is also estimated by the present method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02133667
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