Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1573-904X
    Keywords: drug delivery ; diabetes mellitus ; excipient ; insulin ; eye ; nose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1432-1424
    Keywords: insulin ; brush border membranes ; kidney ; receptors ; binding ; degradation ; tubules ; protein reabsorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The kidney plays a major role in the handling of circulating insulin in the blood, primarily via reuptake of filtered insulin at the luminal brush border membrane.125I-insulin associated with rat renal brush border membrane vesicles (BBV) in a time-and temperature-dependent manner accompanied by degradation of the hormone to trichloroacetic acid (TCA)-soluble fragments. Both association and degradation of125I-insulin were linearly proportional to membrane protein concentration with virtually all of the degradative activity being membrane assoicated. Insulin, proinsulin and desoctapeptide insulin all inhibited the association and degradation of125I-insulin by BBV, but these processes were not appreciably afected by the insulin-like growth factors IGF-I and IGF-II or by cytochromec and lysozyme, low molecular weight, filterable, proteins, which are known to be reabsorbed in the renal tubules by luminal endocytosis. When the interaction of125I-insulin with BBV was studied at various medium osmolarities (300–1100 mosm) to alter intravesicular space, association of the ligand with the vesicles was unaffected, but degradation of the ligand by the vesicles decreased progressively with increasing medium osmolarity. Therefore, association of125I-insulin to BBV represented binding of the ligand to the membrane surface and not uptake of the hormone or its degradation products into the vesicles. Attempts to crosslink125I-insulin to a high-affinity insulin receptor using the bifunctional reagent disuccinimidyl suberate revealed only trace amounts of an125I-insulin-receptor complex in brush border membrane vesicles in contrast to intact renal tubules where this complex was readily observed. Both binding and degradation of125I-insulin by brush border membranes did not reach saturation even at concentrations of insulin approaching 10−5 m. These results indicate the presence of low-affinity, high-capacity binding sites for125I-insulin on renal brush border membranes which can clearly distinguish insulin from the insulin-like growth factors and other low molecular weight proteins and polypeptides, but which do not differentiate insulin from its analogues ad do the biological receptors for the hormone. The properties and location of these binding sites make them attractive candidates for the sites at which insulin is reabsorbed in the renal tubule.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1573-4919
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of diamide were studied in rat kidney cortical tissue. It was found that diamide increased oxidized glutathione levels and inhibited Na+-K+-ATPase activity. Consistent with this finding was the observation that diamide compromised the sodium gradients maintained in renal cortical slices. Amino acid transport studies with ouabain or a sodium-free buffer indicated that diamide interferes with both Na+-dependent and Na+-independent transport systems. These results indicate that diamide has a number of different effects on renal cortical tissue and emphasize the important role of glutathione in maintaining control of a number of key metabolic pathways.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0091-7419
    Keywords: cytochalasin B ; insulin action ; adipocytes ; plasma membranes ; D-glucose transport ; protein reagents ; membrane reconstitution ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Sensitivity of the adipocyte D-glucose transport system in intact plasma membranes or following solubilization and reconstitution into phospholipid vesicles to several protein-modifying reagents was investigated. When intact plasma membranes were incubated with N-ethylmaleimide (20 mM) or fluorodinitrobenzene (4 mM), D-glucose transport activity was virtually abolished. However, washing the membranes free of unreacted reagents restored transport activity, indicating that covalent interaction with the membranes did not mediate the transport inhibition. Reaction of [3H] N-ethylmaleimide with plasma membranes under similar conditions resulted in extensive labeling of all protein fractions resolved on dodecyl sulfate gels. Similarly, addition of N-ethyl-maleimide to cholate-solubilized membrane protein had no effect on transport activity in artifical phospholipid vesicles reconstituted under conditions where the membrane protein was free of unreacted N-ethylmaleimide. Transport activity in plasma membranes was also inhibited by both reduced and oxidized dithiothreitol or glutathione (15 mM) in a readily reversible manner, consistent with a noncovalent mode of inhibition. Thus, the insulin-responsive adipocyte D-glucose transport system differs from the red cell hexose transport system in its remarkable insensitivity to modulation by covalent blockade of sulfhydryal or amino groups by the reagents studied.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0091-7419
    Keywords: dimethylmaleic anhydride ; cytochalasin B ; Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Plasma membrane vesicles prepared from adipocytes incubated with insulin exhibited accelerated D-glucose transport activity characteristic of insulin action on intact fat cells. Both control and insulin-stimulated D-glucose transport activities were inhibited by cytochalasin B and thiol reagents. Extraction of plasma membranes with dimethylmaleic anhydride eluted 80% of the protein from plasma membrane vesicles. The two major glycoprotein bands (94,000 and 78,000 daltons) and small amounts of a 56,000-dalton band were retained in dodecyl sulfate gels of the extracted membranes. Both control and insulin-activated D-glucose transport activities were retained by plasma membrane vesicles extracted with dimethylmaleic anhydride. Cytochalasin B binding activity was also retained by extracted membrane vescles and D-glucose uptake into extracted vescles derived from untreated or insulin-treated fat cells was inhibited by cytochalasin B. These results suggest that the modification of the adipocyte hexose transport system elicited by insulin action is not altered by a major purification step which involves quantitative extraction of extrinsic membrane proteins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 125 (1985), S. 243-250 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sulfate transport in a fibroblast cell line derived from human lung (IMR-90) occurred mainly via high- and low-affinity, SITS-sensitive pathways and to a lesser extent by an SITS-insensitive mechanism. In low-ionic-strength media (sucrose substituted for salts) the apparent Km of the carrier-mediated sulfate influx was 1 mM. At 0.3 mM, the sulfate concentration normally found in human serum, the contribution of the SITS-insensitive pathway was negligible. In physiological salts solution, an SITS-sensitive, high-affinity (Km 34 ± 14 μM) sulfate influx system was observed at extracellular sulfate concentrations less than 100 μM. Between 100 and 500 μM sulfate, the range normally found in human serum, sulfate influx occurred via an SITS-insitive, lowaffinity pathway and to a small extent by an SITS-insensitive mechanism. Extracellular chloride inhibited the influx and stimulated the efflux of sulfate. Bicarbonate and thiosulfate inhibited sulfate influx but had no effect on sulfate efflux. Phosphate, arsenate, or Na+ did not affect sulfate uptake. These results indicate that in human lung fibroblast IMR-90 cells sulfate is transported mainly via an SO42-/Cl- exchange system independent of the phosphate or Na+ transport. Since sulfate concentration as high as 50 mM only slightly increased sulfate efflux, SO42-/SO42- exchange is probably a minor component of sulfate uptake.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...