| 11. |
- Campagnoli, Monica, et al.
(författare)
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A novel splicing mutation causes an undescribed type of analbuminemia.
- 2002
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Ingår i: Biochimica et biophysica acta. - 0006-3002. ; 1586:1, s. 43-9
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Tidskriftsartikel (refereegranskat)abstract
- Analbuminemia is a rare autosomal recessive disorder manifested by the absence or severe reduction of circulating serum albumin in homozygous subjects. In this report we describe a new molecular defect that caused the analbuminemic trait in a newborn of Iraqi origin. When the parents' DNA was analyzed, both subjects were found to be heterozygous for the same mutation found in the infant. All the 14 exon and flanking intron sequences of the albumin gene were amplified via PCR and screened for mutations by SSCP and heteroduplex analysis. A mutation in the DNA region encoding exon 1 and its flanking intron was revealed by the presence of a heteroduplex. The fragment, which was directly DNA sequenced, contains a previously unreported single nucleotide change, consisting in a G to A substitution at nucleotide 118 in the structural gene of the human protein. This mutation, involving the first base of intron 1, destroys the GT dinucleotide consensus sequence found at the 5' end of most intervening sequences and causes the defective pre-mRNA splicing responsible for the analbuminemic trait.
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| 12. |
- Jeppsson, Jan-Olof, et al.
(författare)
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Approved IFCC reference method for the measurement of HbA1c in human blood.
- 2002
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Ingår i: Clinical Chemistry and Laboratory Medicine. - 1434-6621. ; 40:1, s. 78-89
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Tidskriftsartikel (refereegranskat)abstract
- HbA1C is the stable glucose adduct to the N-terminal group of the beta-chain of HbA0. The measurement of HbA1c in human blood is most important for the long-term control of the glycaemic state in diabetic patients. Because there was no internationally agreed reference method the IFCC Working Group on HbA1c Standardization developed a reference method which is here described. In a first step haemoglobin is cleaved into peptides by the enzyme endoproteinase Glu-C, and in a second step the glycated and non-glycated N-terminal hexapeptides of the beta-chain obtained are separated and quantified by HPLC and electrospray ionisation mass spectrometry or in a two-dimensional approach using HPLC and capillary electrophoresis with UV-detection. Both principles give identical results. HbA1c is measured as ratio between the glycated and non-glycated hexapeptides. Calibrators consisting of mixtures of highly purified HbA1c and HbA0 are used. The analytical performance of the reference method has been evaluated by an international network of reference laboratories comprising laboratories from Europe, Japan and the USA. The intercomparison studies of the network showed excellent results with intra-laboratory CVs of 0.5 to 2% and inter-laboratory CVs of 1.4 to 2.3%. Possible interferences have been carefully investigated. Due to the higher specificity of the reference method the results are lower than those generated with most of the present commercial methods which currently are calibrated with unspecific designated comparison methods. The new reference method has been approved by the member societies of the International Federation of Clinical Chemistry and Laboratory Medicine and will be the basis for the future uniform standardization of HbA1c routine assays worldwide.
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| 13. |
- Jonasson, Torfi, et al.
(författare)
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Renal function exerts only a minor influence on high plasma homocysteine concentrations in patients with acute coronary syndromes.
- 2002
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Ingår i: Clinical Chemistry and Laboratory Medicine. - 1434-6621. ; 40:2, s. 137-142
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that hyperhomocysteinemia observed in patients with occlusive vascular disease is caused by reduced renal function secondary to renovascular disease. We have therefore used serum cystatin C, a new sensitive marker for glomerular filtration, in 59 patients with acute coronary syndromes and high plasma homocysteine (tHcy) concentration to measure renal function. Samples were also obtained from 34 patients with low-normal plasma tHcy and 50 control subjects. The patients with low-normal plasma tHcy concentration showed decreased concentrations of serum cystatin C and serum creatinine and increased concentrations of blood folate and serum cobalamin compared to the controls and to the patients with high plasma tHcy. There was a large overlap in cystatin C concentrations between patients with high and low-normal plasma tHcy. None of the parameters investigated except plasma tHcy were significantly different in the group of patients with high plasma tHcy concentration compared to the control group. In order to further demonstrate the importance of renal impairment, a subgroup of the patients with high plasma tHcy was supplemented daily with folic acid 5 mg, pyridoxine 40 mg and cyancobalamin 1 mg for 3 months. Vitamin therapy reduced plasma tHcy from 18.3+/-4.6 pmol/l to 9.6+/-2.2 pmol/l (p<0.0001). However, vitamin treatment did not strengthen the correlation between cystatin C and plasma tHcy concentrations. These findings do not support the hypothesis that subtle renal dysfunction is an important cause of high plasma tHcy concentration in patients with acute coronary syndromes.
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| 14. |
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| 15. |
- Olofsson, A., et al.
(författare)
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Amyloid : Morphology and Toxicity
- 2002
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Ingår i: Clinical Chemistry and Laboratory Medicine. - 1434-6621 .- 1437-4331. ; 40:12, s. 1266-1270
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Tidskriftsartikel (refereegranskat)abstract
- We have expressed transthyretin (TTR) mutants which have significantly destabilised tetramers that aggregate into amyloid fibrils via a series of intermediates. We used atomic force microscopy to follow the morphology of aggregates during fibril formation. Initially, amorphous aggregates are formed that subsequently mature into fibrillar structures. This observation is interpreted as an optimisation of beta-strand registers. The rate of aggregation and maturation is highly temperature-dependent suggesting that entropic forces significantly contribute to stability. In addition, we identified a correlation between the presence of early formed aggregates of TTR and cytotoxicity. The toxic response was mediated via an apoptotic mechanism. The fact that early formed amorphous aggregates, but not more mature fibrils, exert a toxic response suggests that the rate of fibril formation may be a critical parameter. We propose that a slow rate of aggregation facilitates an increased concentration of a toxic intermediate.
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| 16. |
- Zetterberg, Henrik, 1973, et al.
(författare)
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Increased frequency of combined methylenetetrahydrofolate reductase C677T and A1298C mutated alleles in spontaneously aborted embryos.
- 2002
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Ingår i: European journal of human genetics : EJHG. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 10:2, s. 113-8
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Tidskriftsartikel (refereegranskat)abstract
- The pathogenesis of spontaneous abortion is complex, presumably involving the interaction of several genetic and environmental factors. The methylenetetrahydrofolate reductase (MTHFR) gene C677T and A1298C polymorphisms are commonly associated with defects in folate dependent homocysteine metabolism and have been implicated as risk factors for recurrent embryo loss in early pregnancy. In the present study we have determined the prevalence of combined MTHFR C677T and A1298C polymorphisms in DNA samples from spontaneously aborted embryos (foetal death between sixth and twentieth week after conception) and adult controls using solid-phase minisequencing technique. There was a significant odds ratio of 14.2 (95% CI 1.78-113) in spontaneously aborted embryos comparing the prevalence of one or more 677T and 1298C alleles vs the wild type combined genotype (677CC/1298AA), indicating that the MTHFR polymorphisms may have a major impact on foetal survival. Combined 677CT/1298CC, 677TT/1298AC or 677TT/1298CC genotypes, which contain three or four mutant alleles, were not detected in any of the groups, suggesting complete linkage disequilibrium between the two polymorphisms. The present finding of high prevalence of mutated MTHFR genotypes in spontaneously aborted embryos emphasises the potential protective role of periconceptional folic acid supplementation.
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| 17. |
- Zetterberg, Henrik, 1973, et al.
(författare)
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Influence of the apolipoprotein E epsilon4 allele on human embryonic development.
- 2002
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Ingår i: Neuroscience letters. - 0304-3940. ; 324:3, s. 189-92
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Tidskriftsartikel (refereegranskat)abstract
- Human apolipoprotein E (apoE) exists in three major isoforms encoded by distinct alleles (APOE epsilon2, epsilon3 and epsilon4) and has important functions in nerve development and repair. Inheritance of the 4 allele is a major risk factor for the development of Alzheimer's disease. To investigate the role of APOE polymorphisms in embryonic development, we analyzed the APOE genotypes of 81 spontaneously aborted embryos and 110 adult controls using a solid-phase minisequencing technique. The epsilon4 allele was significantly less frequent in the spontaneous abortion group than in the control group (P=0.009), while the frequency of epsilon3 was significantly increased (P=0.005), suggesting that epsilon4 may have protective effects during embryogenesis. These protective effects might counterbalance the deleterious age-related effects of the epsilon4 allele in natural selection.
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