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- Lindskog, Bengt I., et al.
(författare)
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Medicinsk terminologi
- 2004
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Bok (övrigt vetenskapligt/konstnärligt)
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| 4. |
- Arnadottir, Margret, et al.
(författare)
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Effects of short-term treatment with corticotropin on the serum apolipoprotein pattern
- 2001
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 61:4, s. 301-306
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Tidskriftsartikel (refereegranskat)abstract
- Treatment with adrenocorticotrophic hormone (ACTH) has a well-documented cholesterol-lowering effect. Increased uptake of low-density lipoprotein (LDL) by HepG2 cells in response to incubation with ACTH has been demonstrated but the precise cholesterol-lowering mechanism has resisted elucidation. Since apolipoproteins are important determinants of lipoprotein metabolism, we sought to extend the knowledge of the effect of ACTH treatment on the serum apolipoprotein (apo) pattern. Twelve healthy individuals and 14 dyslipoproteinemic hemodialysis patients were recruited. The two groups responded similarly to ACTH1-24 at the dose of 1 mg daily for four days. In accordance with previous results, serum concentrations of total cholesterol decreased by 18% and 17%, LDL cholesterol by 25% and 30%, and apo B by 20% and 19%, respectively, while there were no significant changes in the serum concentrations of triglycerides, high-density lipoprotein cholesterol and apo AI. Novel findings were that the serum concentrations of total apo E increased by 48% and 31%, and apo B-associated apo E by 69% and 46%, respectively. Moreover, in the healthy individuals, the serum concentrations of apo CIII did not change in response to ACTH, whereas in the hemodialysis patients, those of apo CIII not associated with apo B increased significantly by 44%. Since apo E binds strongly to the LDL receptor, the present results suggest that the cholesterol-lowering effect of ACTH may be mediated by facilitated hepatic uptake of apo E-enriched apo B-containing lipoproteins. Thus, the findings stimulate further research.
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- Berggren Söderlund, Maria, et al.
(författare)
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Biological variation of retinoids in man.
- 2002
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Ingår i: Scandinavian Journal of Clinical & Laboratory Investigation. - : Informa UK Limited. - 1502-7686 .- 0036-5513. ; 62:7, s. 511-519
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Tidskriftsartikel (refereegranskat)abstract
- This investigation was undertaken to assess biological variation, especially the within-subject variations of all- trans retinoic acid, 13- cis retinoic acid and retinol in human serum. Diurnal variation and variation over a week, a month and a year were studied in 11 males (aged 21 - 54 years) and 17 females (aged 22 - 63 years), all subjectively healthy. We found no diurnal variation with the exception of all- trans retinoic acid, which had maximal concentrations at noon irrespective of food intake. Seasonal variations were marginal. Both all- trans and 13- cis retinoic acids had fairly high within-subject (13.1% and 12.6%, respectively) and between-subject coefficients of variation (15.9% and 21.0%, respectively), while the within-subject CV of retinol was less (5.6%, with a between-subject CV of 21.1%). Thus, the indices of individuality were <1 for all retinoids. The critical differences between two consecutive samples were <40% for the retinoic acids and <20% for retinol. Women had higher all- trans retinoic acid concentrations in serum (5.1 nmol/L vs. 4.5 nmol/L), lower 13- cis retinoic acid concentrations (4.5 nmol/L vs. 5.5 nmol/L) and lower retinol concentrations in serum (2.1 µmol/L vs. 2.5 µmol/L) than men. Thus, samples for retinoid determinations should be drawn in the morning and evaluated using separate gender reference intervals.
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- Boren, Jan, et al.
(författare)
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The molecular mechanism for the genetic disorder familial defective apolipoprotein B100
- 2001
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 276:12, s. 9214-9218
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Tidskriftsartikel (refereegranskat)abstract
- Familial defective apolipoprotein B100 (FDB) is a genetic disorder in which low density lipoproteins (LDL) bind defectively to the LDL receptor, resulting in hypercholesterolemia and premature atherosclerosis. FDB is caused by a mutation (R3500Q) that changes the conformation of apolipoprotein (apo) B100 near the receptor-binding site. We previously showed that arginine, not simply a positive charge, at residue 3500 is essential for normal receptor binding and that the carboxyl terminus of apoB100 is necessary for mutations affecting arginine 3500 to disrupt LDL receptor binding. Thus, normal receptor binding involves an interaction between arginine 3500 and tryptophan 4369 in the carboxyl tail of apoB100. W4369Y LDL and R3500Q LDL isolated from transgenic mice had identically defective LDL binding and a higher affinity for the monoclonal antibody MB47, which has an epitope flanking residue 3500. We conclude that arginine 3500 interacts with tryptophan 4369 and facilitates the conformation of apoB100 required for normal receptor binding of LDL. From our findings, we developed a model that explains how the carboxyl terminus of apoB100 interacts with the backbone of apoB100 that enwraps the LDL particle. Our model also explains how all known ligand-defective mutations in apoB100, including a newly discovered R3480W mutation in apoB100, cause defective receptor binding.
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- Ekström, Ulf, et al.
(författare)
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Expression of an LDL receptor allele with two different mutations (E256K and I402T)
- 2000
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Ingår i: Molecular Pathology. - 1366-8714. ; 53:1, s. 31-36
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To investigate the disease causing event in patients with familial hypercholesterolaemia, carrying two mutations each, E256K in exon 6 and I402T in exon 9, of the gene encoding the low density lipoprotein (LDL) receptor. It was not known whether the mutations were positioned in cis or trans, or if they were each pathogenic separately or only when present together. METHODS: Polymerase chain reaction, denaturing gradient gel electrophoresis and sequencing were used to characterise the LDL receptor locus of the patients and family members. The different LDL receptor mutants, constructed in vitro by oligonucleotide directed mutagenesis, were expressed in LDL receptor deficient Chinese hamster ovary (CHO1d1A7) cells, to determine the effects of the mutations on LDL receptor function. RESULTS: The two mutations were located on the same allele of the LDL receptor gene. All mutant constructs resulted in the production of a detectable protein in CHO cells. The cells expressing only the I402T mutation, or the combination of I402T and E256K mutations, were seriously affected in mediating uptake and degradation of LDL. Contrary to initial predictions, the cells expressing only the E256K mutation showed essentially the same binding, uptake, and degradation of 125I labelled LDL as cells transfected with normal LDL receptor cDNA. These results suggest that the pathogenic mutation in the patients heterozygous for the E256K/I402T allele is the I402T mutation, and that E256K alone is a rare sequence variation, which does not affect LDL receptor protein function. E256K was not detected either in DNA from a healthy population or in DNA from other hypercholesterolaemic patients studied. CONCLUSIONS: Despite the information available on the structure-function relations between the LDL receptor and LDL receptor like proteins, predictions about the disease causing potential of a mutation are not reliable. These results suggest that the I402T mutation is pathogenic and that the substitution of E256K alone is a rare sequence variation, without a detectable phenotype modulating effect.
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