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- Ristow, M, et al.
(författare)
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Deficiency of phosphofructo-1-kinase/muscle subtype in humans is associated with impairment of insulin secretory oscillations
- 1999
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 48:8, s. 1557-1561
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Tidskriftsartikel (refereegranskat)abstract
- In healthy humans, insulin is secreted in an oscillatory manner. While the underlying mechanisms generating these oscillations are not fully established, increasing evidence suggests a central role for phosphofructo-1-kinase/muscle subtype (PFK1-M), which also serves as the predominantly active PFK1 subtype in the pancreatic beta-cell. The fact that normal oscillatory secretion is impaired in subjects with impaired glucose tolerance and healthy relatives of patients with type 2 diabetes suggests that this defect may be involved in the secretory dysfunction. To evaluate a possible link between inherited PFK1-M deficiency in humans (Tarui's disease or glycogenosis type VII) and altered insulin oscillations, in vivo studies were performed. We determined basal insulin oscillations during 2 h of frequent plasma sampling in two related teen-aged individuals with homozygous and heterozygous PFK1-M deficiency compared with nondeficient, unrelated control subjects. As predicted by the underlying hypothesis, normal oscillations in insulin secretion were completely abolished in the individual with homozygous deficiency of PFK1-M and significantly impaired in the heterozygous individual, as shown by spectral density and autocorrelation analyses. Thus, deficiency of PFK1-M subtype in humans appears to be associated with an impaired oscillatory insulin secretion pattern and may contribute to the commonly observed secretion defects occurring in type 2 diabetes.
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- Malmsten, M, et al.
(författare)
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Interfacial behaviour of 'new' poly(ethylene oxide)-containing copolymers
- 1999
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Ingår i: Journal of Biomaterials Science. Polymer Edition. - 0920-5063 .- 1568-5624. ; 10, s. 1075-1087
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Tidskriftsartikel (refereegranskat)abstract
- Block copolymers containing poly(ethylene oxide) (PEO) have a wide applicability within biomedical applications, not the least due to anti-fouling properties of surface coatings based on these copolymers. We have investigated a number of these, and results for PEO/poly(butylene oxide) (PEO/PBO), PEO/poly(lactide) (PEO/PL), and PEO/poly(ethylene imine) (PEO/PEI) copolymers, as well as for PEO-esterified fatty acids, are presented and discussed. For the former class of polymers, the effects of molecular architecture on the adsorption properties are adressed, and experimental results obtained with ellipsometry and small-angle neutron scattering presented. For the PEO/PL block copolymers, the effects of the PEO and PL lengths for the polymer adsorption are adressed, as are the effects of degradation of the PL moiety on both adsorption and protein rejection. For the PEO-esterified fatty acids, the effects of PEO chain length and interfacial density on the protein rejection capacity of such coatings are discussed.
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- Malmsten, M, et al.
(författare)
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Sequential adsorption of human serum albumin (HSA), immunoglobulin G (IgG), and fibrinogen (Fgn) at HMDSO plasma polymer surfaces
- 1997
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Ingår i: Journal of Colloid and Interface Science. - 0021-9797 .- 1095-7103. ; 193, s. 88-95
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Tidskriftsartikel (refereegranskat)abstract
- The sequential adsorption of human serum albumin (HSA), immunoglobulin G (IgG), and fibrinogen (Fgn) at hexamethyldisiloxane (HMDSO) plasma polymer surfaces was investigated with ellipsometry and total internal reflectance fluorescence spectroscopy (TIRF) as a function of adsorption time, pH, and excess electrolyte concentration. HSA was found to self-exchange very slowly (≈hours) at pH 7.2, irrespective of adsorption time in the range 90 seconds to 90 minutes. Preadsorbed HSA was exchanged by Fgn and IgG only to a limited extent irrespectively of pH (5≤pH≤8) and excess electrolyte concentration (5 mM≤Cs≤150 mM). At an excess electrolyte concentration of 150 mM, the sequential adsorption of Fgn and IgG was dramatically reduced by HSA preadsorption, irrespective of pH. At an excess electrolyte concentration of 5 mM, on the other hand, there were indications of second layer adsorption of Fgn and IgG.
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| 9. |
- Muller, D, et al.
(författare)
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Competitive adsorption of gelatin and sodium dodecylbenzenesulfonate at hydrophobic surfaces
- 1998
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Ingår i: Langmuir. - 0743-7463 .- 1520-5827. ; 14, s. 3107-3114
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Tidskriftsartikel (refereegranskat)abstract
- The competitive adsorption of gelatin and sodium dodecylbenzenesulfonate (SDBS) at hydrophobic surfaces was investigated with surface and interfacial tension measurements, ellipsometry, surface plasmon resonance spectroscopy (SPR), and total internal reflectance fluorescence spectroscopy (TIRF). From both ellipsometry and SPR, initial additions of SDBS after gelatin preadsorption were found to result in a total adsorbed amount increase, as well as in a swelling of the adsorbed layer. At higher SDBS concentrations, both the total adsorbed amount and the amount of gelatin adsorbed decrease, which was observed from ellipsometry, SPR, and TIRF. From surface and interfacial tension measurements, it was found that the critical aggregation concentration (cac) for the SDBS-gelatin system decreases with decreasing pH. Analogous to this, ellipsometry, SPR, and TIRF indicate that the SDBS concentration required to cause a significant decrease in the gelatin adsorbed amount decreases with decreasing pH. The desorption therefore seems to be correlated to the SDBS binding to the adsorbed gelatin molecules rather than to purely competitive adsorption.
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- Muller, D, et al.
(författare)
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Interaction of gelatin and sodium dodecyl benzene sulphonate at oil and water interfaces
- 1997
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Ingår i: Imaging Science Journal. - 1368-2199 .- 1743-131X. ; 45, s. 229-235
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Tidskriftsartikel (refereegranskat)abstract
- Interaction between sodium dodecyl benzene sulphonate (SDBS) and gelatin was studied in relation to emulsification behaviour and emulsion stability. We chose two different oils to study influences of oil phase characteristics, namely, tricresyl phosphate (TCP) as an oil with polar and slightly hydrophilic nature, and n-docedane (nC12) as its apolar contrast. Our interfacial tension measurements showed that both TCP and n-C12 give critical values (i.e., cac and cmc) very close to those of surface tension measurement. This result indicates that the complexation behaviour in bulk solution is independent of the presence or the nature of the oil phase. Absolute tension values above the cmc and slope values at the cmc in gelatin free systems, however, imply SDBC's weaker adsorption to TCP than to n-C12. Our emulsification results for the TCP system revealed the existence of an optiomal point for emulsion stability in the SDBS concentration region between the cac and the cmc. Above this point, emulsion stability deteriorates remarkably. The behaviour is in line with our findings from the dynamic sorption expriments (ellipsometry, TIRF, and SPR) reported elsewhere, which showed a rapid desorption of gelatin from the hydrophobic surfaces above the cac. The results suggest that the adsorption of gelatin/ surfactant complexes at the interface is a key factor for stability of the polar oil emulsion system. Contrary to that , the n-c12 system did not show any deterioration, even above the cmc, which is presumably due to a strong double layer effect from the firmly adsorbed layer of SDBS at the interface.
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