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- Hedberg, U., et al.
(författare)
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Miniaturized thermal biosensors
- 1996
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Ingår i: Biochemical Technology. - 1569-2558. - 0762301147 - 9780762301140 ; 15, s. 499-505
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Bokkapitel (refereegranskat)abstract
- A summary of our efforts to develop miniaturized biosensors based on the enzyme thermistor is presented. Three constructions are described. The work focuses on the measurement of glucose in whole blood.The first biosensor was used to analyze concentrated and tenfold diluted blood samples. The glucose concentration obtained using this construction correlated well with the reference method.Using the second biosensor, the response time could be reduced from 3 minutes down to 30 seconds using a sample volume of 1 μl. The relative standard deviation for 100 blood samples (3.8 tnM) was 3.7%.Micromachining technology was used to construct the third thermal biosensor on a silicon chip. Enzymes were immobilized directly onto the 30 parallel flow channels. Injection of 200 samples containing 10 mM hydrogen peroxide gave a relative standard deviation of 3%.
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| 2. |
- Bülow, Birgitta, et al.
(författare)
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Individualized low-dose growth hormone (GH) treatment in GH-deficient adults with childhood-onset disease: metabolic effects during fasting and hypoglycemia
- 1999
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Ingår i: Metabolism, Clinical and Experimental. - 1532-8600. ; 48:8, s. 10-1003
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Tidskriftsartikel (refereegranskat)abstract
- Growth hormone (GH) has insulin-antagonistic effects, and GH secretion is augmented during fasting and hypoglycemia. In the present study, 10 patients aged 21 to 28 years with childhood-onset GH deficiency (GHD) were studied during a 24-hour fast and a hypoglycemic glucose clamp before and after 9 months of GH replacement. During the 24-hour fast, blood glucose, serum insulin, and serum free fatty acid (FFA) levels were measured. In the hypoglycemic clamp, the counterregulatory hormones (plasma catecholamines, serum glucagon, and serum cortisol), serum insulin-like growth factor (IGF) binding protein-1 (IGFBP-1), serum FFA, and glucose uptake were measured. The GH dose was adjusted to the response of serum IGF-I, and the median GH dose was 0.14 IU/kg/wk (range, 0.08 to 0.19). At the end of the study, serum IGF-I levels were normalized in all but one patient, in whom serum IGF-I was above the normal range. Nine months of GH treatment did not cause any significant changes in the blood glucose level, insulin to glucose ratio, or serum FFA level during the 24-hour fast, and none of the patients experienced hypoglycemia either before or after GH treatment. However, GH therapy resulted in increased insulin resistance during hypoglycemia, without changes in the counterregulatory hormonal responses, serum IGFBP-1, or serum FFA.
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| 6. |
- Walse, B, et al.
(författare)
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Structure of a cyclic peptide with a catalytic triad, determined by computer simulation and NMR spectroscopy
- 1996
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Ingår i: Journal of Computer-Aided Molecular Design. - 0920-654X. ; 10:1, s. 11-22
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Tidskriftsartikel (refereegranskat)abstract
- We report the design of a cyclic, eight-residue peptide that possesses the catalytic triad residues of the serine proteases. A manually built model has been relaxed by 0.3 ns of molecular dynamics simulation at room temperature, during which no major changes occurred in the peptide. The molecule has been synthesised and purified. Two-dimensional NMR spectroscopy provided 35 distance and 7 torsion angle constraints, which were used to determine the three-dimensional structure. The experimental conformation agrees with the predicted one at the beta-turn, but deviates in the arrangement of the disulphide bridge that closes the backbone to a ring. A 1.2 ns simulation at 600 K provided extended sampling of conformation space. The disulphide bridge reoriented into the experimental arrangement, producing a minimum backbone rmsd from the experimental conformation of 0.8 A. At a later stage in the simulation, a transition at Ser3 produced more pronounced high-temperature behaviour. The peptide hydrolyses p-nitrophenyl acetate about nine times faster than free histidine.
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