| 1. |
- Angsten, G., et al.
(author)
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Reference ranges for muscle carnitine concentration in children
- 2003
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632 .- 1758-1001. ; 40:4, s. 406-410
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Journal article (peer-reviewed)abstract
- Background: We investigated muscle and plasma carnitine concentrations in children to establish reference intervals for use following biopsy of skeletal muscle. Methods: The study comprised 50 children from newborns up to 14 years of age, all undergoing elective surgery. They were divided into six age groups, the youngest 0-2 days and the oldest 11-14 years. The samples were taken at the beginning of surgery. Results: Gestational age was a major determinant of the total muscle carnitine concentration in newborns (Spearman's rs= 0.692, P<0.01). This concentration was low during the first year, but subsequently did not differ between age groups. In neonates the median value (range) for total carnitine concentration in skeletal muscle was 5.9 (2.2-15.9) µmol/g dry weight and the free to total carnitine ratio was 62 (31-81)%. In children 1-12 months old the corresponding figures were 6.0 (3.5-7.9) µmol/g dry weight and 51 (28-71)% and in those 1-14 years they were 12.1 (6.6-17.4) µmol/g dry weight and 76 (42-92)%. Conclusion: This study shows that muscle carnitine concentrations in newborns are dependent on gestational age. The data suggest that there is an accretion of carnitine in skeletal muscle during the first year of life. Reference intervals are given.
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| 2. |
- Ayling, P, et al.
(author)
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A practical tool for monitoring the performance of measuring systems in a laboratory network: report of an ACB Working Group
- 2017
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In: Annals of clinical biochemistry. - : SAGE Publications. - 1758-1001. ; 54:6, s. 702-706
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Journal article (peer-reviewed)abstract
- A logical consequence of the introduction of robotics and high-capacity analysers has seen a consolidation to larger units. This requires new structures and quality systems to ensure that laboratories deliver consistent and comparable results. Methods A spreadsheet program was designed to accommodate results from up to 12 different instruments/laboratories and present IQC data, i.e. Levey-Jennings and Youden plots and comprehensive numerical tables of the performance of each item. Input of data was made possible by a ‘data loader’ by which IQC data from the individual instruments could be transferred to the spreadsheet program on line. Results A set of real data from laboratories is used to populate the data loader and the networking software program. Examples are present from the analysis of variance components, the Levey-Jennings and Youden plots. Conclusions This report presents a software package that allows the simultaneous management and detailed monitoring of the performance of up to 12 different instruments/laboratories in a fully interactive mode. The system allows a quality manager of networked laboratories to have a continuous updated overview of the performance. This software package has been made available at the ACB website.
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| 3. |
- Beck, O, et al.
(author)
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Frontline immunochromatographic device for on-site urine testing of amphetamines: laboratory validation using authentic specimens
- 2000
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In: Annals of clinical biochemistry. - : SAGE Publications. - 0004-5632. ; 3737 ( Pt 2), s. 199-204
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Journal article (peer-reviewed)abstract
- We evaluated a new test device for amphetamines and methamphetamines (Frontline ®, cut-off limit 300 ng/mL) using authentic clinical and forensic specimens. The device is based on immunochromatography and is dipped into urine and read visually by comparison with a colour scale after a few minutes. A total of 658 specimens were tested by comparing results of the screening procedure with established immunoassays. Discordant results were further investigated by gas chromatography- mass spectrometry or gas chromatography (with flame ionization detector). The Frontline device had a sensitivity of 93% and a specificity of 98%. When specimens were classified by urine amphetamine concentration, close agreement was obtained at concentrations below 150 ng/mL and above 1000 ng/mL. A small number of specimens with amphetamine concentrations between 300 and 1000 ng/mL tested negative in the Frontline test. This finding could to some extent be explained by the enantioselectivity of the antibodies in the Frontline test to d-amphetamine. We conclude that the performance of the Frontline test device for amphetamines is adequate for presumptive clinical and forensic screening.
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| 4. |
- Berry, D, et al.
(author)
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New antiepileptic drugs
- 2000
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In: Annals of clinical biochemistry. - 0004-5632. ; 3737 ( Pt 4), s. 551-553
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Journal article (other academic/artistic)
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| 5. |
- Bozic-Mijovski, M, et al.
(author)
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Diluted thrombin time reliably measures low to intermediate plasma dabigatran concentrations
- 2016
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In: Annals of clinical biochemistry. - : SAGE Publications. - 1758-1001. ; 53:4Pt 4, s. 446-451
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Journal article (peer-reviewed)abstract
- Direct oral anticoagulant dabigatran was first introduced as a fixed-dose drug without routine coagulation monitoring, but current recommendations suggest that diluted thrombin time can be used to estimate plasma drug level. The aim of this study was to assess a diluted thrombin time assay based on the same thrombin reagent already used for traditional thrombin time measurements that reliably measure low to intermediate plasma dabigatran levels. Methods We included 44 patients with atrial fibrillation who started treatment with dabigatran 150 mg (23 patients) or 110 mg (21 patients) twice a day. Blood samples were collected at baseline (no dabigatran) and 2–4 weeks after the beginning of dabigatran therapy at trough and at peak. Plasma dabigatran levels were measured with diluted thrombin time and compared to liquid chromatography with tandem mass spectrometry as the reference method. The performance of the diluted thrombin time was compared to Hemoclot® Thrombin Inhibitor and Ecarin Chromogenic Assay. Results In ex vivo plasma samples, diluted thrombin time highly correlated with the liquid chromatography with tandem mass spectrometry (Pearson’s R = 0.9799). In the low to intermediate range (dabigatran concentration ≤ 100 µg/L) diluted thrombin time correlated significantly more closely to the liquid chromatography with tandem mass spectrometry (R = 0.964) than Hemoclot® Thrombin Inhibitor (R = 0.935, p = 0.05) or Ecarin Chromogenic Assay (R = 0.915, p < 0.01). It was also the only functional assay without any significant bias in the low to intermediate range. Both trough and peak diluted thrombin time values were similar to liquid chromatography with tandem mass spectrometry. Conclusion We conclude that the diluted thrombin time assay presented in this study reliably detects dabigatran and that it is superior to the Hemoclot® Thrombin Inhibitor assay in the low to intermediate range.
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| 6. |
- Casl, Martin-Tino, et al.
(author)
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A rapid enzyme-linked immunosorbent assay for serum amyloid A using sequence-specific antibodies
- 1993
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632. ; 30:3, s. 278-286
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Journal article (peer-reviewed)abstract
- A microtitre plate based enzyme-linked immunosorbent assay for determining the concentration of serum amyloid A (SAA) is described. The method employs easily produced sequence-specific rabbit antibodies and the preferential absorption of SAA to polystyrene, which obviates the use of capture antibodies and allows an assay time of only 3.5 h, so that the diagnostic potential of the SAA level as a rapid and reliable marker for inflammation can be fully exploited. The assay has a working concentration range of 0.1-2500 mg/L, which embraces the known biological variation of the SAA concentration. The intra-assay coefficient of variation (CV) for SAA concentrations above 10 mg/L is between 1.6 and 3.3% and the interassay CV between 3.0 and 4.2%. Recovery of SAA added to serum is from 96 to 102%.
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| 7. |
- Cornes, Michael P., et al.
(author)
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The role of European Federation of Clinical Chemistry and Laboratory Medicine Working Group for Preanalytical Phase in standardization and harmonization of the preanalytical phase in Europe
- 2016
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632 .- 1758-1001. ; 53:5, s. 539-547
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Research review (peer-reviewed)abstract
- Patient safety is a leading challenge in healthcare and from the laboratory perspective it is now well established that preanalytical errors are the major contributor to the overall rate of diagnostic and therapeutic errors. To address this, the European Federation of Clinical Chemistry and Laboratory Medicine Working Group for Preanalytical Phase (EFLM WG-PRE) was established to lead in standardization and harmonization of preanalytical policies and practices at a European level. One of the key activities of the WG-PRE is the organization of the biennial EFLM-BD conference on the preanalytical phase to provide a forum for National Societies (NS) to discuss their issues. Since 2012, a year after the first Preanalytical phase conference, there has been a rapid growth in the number of NS with a working group engaged in preanalytical phase activities and there are now at least 19 countries that have one. As a result of discussions with NS at the third conference held in March 2015 five key areas were identified as requiring harmonisation. These were test ordering, sample transport and storage, patient preparation, sampling procedures and management of unsuitable specimens. The article below summarises the work that has and will be done in these areas. The goal of this initiative is to ensure the EFLM WG-PRE produces work that meets the needs of the European laboratory medicine community. Progress made in the identified areas will be updated at the next preanalytical phase conference and show that we have produced guidance that has enhanced standardisation in the preanalytical phase and improved patient safety throughout Europe.
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| 8. |
- Israelsson, Marlen, et al.
(author)
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20α- and 20β-dihydrocortisone may interfere in LC-MS/MS determination of cortisol in saliva and urine
- 2018
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In: Annals of Clinical Biochemistry. - : Sage Publications. - 0004-5632 .- 1758-1001. ; 55:3, s. 341-347
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Journal article (peer-reviewed)abstract
- Background: LC-MS/MS methods offer high selectivity in cortisol determinations. However, endogenous steroid metabolites may still interfere and compromise the results, for example in the diagnosis of Cushing's syndrome. Erroneously elevated cortisol may, in particular, be misleading at the low concentrations found in salivary samples obtained at late night and after dexamethasone suppression.Methods: Interferences in our LC-MS/MS method used for determination of cortisol in saliva and urine were identified by comparing their retention times and mass spectra with those of pure candidate substances. The chromatographic conditions used in our LC-MS/MS method, including column and mobile phase gradient, were varied in order to separate the target compound from the interferences.Results: Two interferences, which were co-eluting or eluting close to cortisol in our original method, were successfully separated from cortisol by adjustment of the chromatographic conditions. These interferences were found in both urine and saliva and were identified as the two endogenous cortisol isomers 20- and 20-dihydrocortisone. The isomers share molecular mass and mass spectrometric fragmentation pattern with cortisol using electrospray ionization in the positive-ion mode. Both give rise to the transitions m/z 363.1>121.1, 363.1>115.1 and 363.1>97.1. In our original LC-MS/MS setup, the 20-dihydrocortisone co-eluted with cortisol in the chromatography step resulting in false high determinations.Conclusions: Cortisol determination by LC-MS/MS may suffer from erroneously elevated results unless 20- and 20-dihydrocortisone are chromatographically separated from cortisol.
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| 9. |
- Landberg, Eva, et al.
(author)
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Serum prolactin and macroprolactin in heart failure: no relation to established laboratory or clinical parameters
- 2011
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In: ANNALS OF CLINICAL BIOCHEMISTRY. - : Blackwell Scientific Publications. - 0004-5632. ; 48, s. 51-56
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Journal article (peer-reviewed)abstract
- Background: A few smaller studies have reported that the prolactin concentration is elevated in connection with heart failure. As heart failure is combined with disturbances of several biological systems any or all of which may also influence prolactin concentrations, we wanted to evaluate the relation of prolactin to prognosis in elderly patients. Methods: A total of 462 elderly patients from a primary health-care centre, all with symptoms of heart failure, were included. In addition to clinical examination including echocardiography, concentrations of prolactin, macroprolactin, C-reactive protein, thyroid-stimulating hormone and N-terminal pro B-type natriuretric peptide (NT-proBNP) were measured. Patients were then followed for 10 y, and all incidents of cardiovascular mortality were registered. Results: After excluding patients with macroprolactin, hyperprolactinaemia was found in 3.7% of the patients. There were no differences in prolactin concentrations or in the frequency of macroprolactin between patients with heart failure and those with normal cardiac function, defined as left ventricular ejection fraction of at least 50%. No significant correlation could be found between NT-proBNP and prolactin. Neither could any association be found between cardiovascular mortality and prolactin concentration during 10 y of follow-up. Conclusions: Prolactin concentrations were not associated with cardiovascular mortality or any clinical or biochemical marker of heart failure. Macroprolactin was found in similar frequency among patients with and without heart failure, and showed no correlation with mortality risk.
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| 10. |
- Larsson, Anders, et al.
(author)
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Reference intervals for parathyroid hormone for 70-year-old males and females : exclusion of individuals from the reference interval based on sex, calcium, diabetes, cardiovascular diseases or reduced kidney function has limited effects on the interval
- 2015
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632 .- 1758-1001. ; 52:1, s. 39-43
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Journal article (peer-reviewed)abstract
- BACKGROUND: A problem when producing reference intervals for elderly individuals is that they often suffer from a number of diseases and they are most often on medication. If all such persons are excluded, there is a risk that the residual subgroup may not be representative of the population, we therefore wanted to compare the effects different exclusion criteria has on the reference intervals.METHODS: We measured parathyroid hormone (PTH), calcium, albumin and cystatin C in a cohort of 70-year-old males and females (n = 1003). Reference intervals for PTH for males and females were calculated for the entire population and after exclusion of persons with calcium >2.60 mmol/L, calcium >2.51 mmol/L, diabetes, reduced glomerular filtration rate (GFR), and cardiovascular diseases.RESULTS: The calculated PTH reference interval 16 (CI 14-17) to 94 (CI 87-101) ng/L. Exclusion of study subjects resulted in smaller reference sample groups, but the reference limits remained within the 90% confidence intervals of the original reference limits. The selections thus had a very limited effect on the calculated reference interval for PTH.CONCLUSIONS: Exclusion of elderly individuals with high calcium concentrations, diabetes, reduced GFR or cardiovascular disease has little effect on the reference interval for PTH. It is better not to exclude these individuals, as it will provide a broader base for the reference interval.
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| 11. |
- Lewerin, Catharina, 1961, et al.
(author)
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Holotranscobalamin is not influenced by decreased renal function in elderly men: the MrOS Sweden study
- 2013
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632 .- 1758-1001. ; 50:6, s. 585-594
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Journal article (peer-reviewed)abstract
- Background Subclinical cobalamin deficiency is common in the elderly, but the sensitivity and specificity of serum total cobalamin for this diagnosis is poor. Serum holotranscobalamin (holoTC), a measure of biologically available cobalamin, is considered a better marker for early cobalamin depletion than total cobalamin. However, in elderly populations, health-related reference intervals for holoTC and correlations to renal function are not entirely clear. Methods HoloTC was determined with an automated microparticle enzyme immunoassay (AxSYM (R)) in 790 elderly non-vitamin-supplemented Swedish men, median age 75.3 years. Renal function was assessed with creatinine, cystatin C and estimated glomerular filtration rate (eGFR calculated from creatinine). Results Median holoTC was 51.8pmol/L, the health-related reference interval 19.6-132.3pmol/L. There was no significant difference in mean holoTC in probands with normal compared to high creatinine (P=0.80) and cystatin C (P=0.82). No significant differences between the quartiles of creatinine or cystatin C in mean of log holoTC were seen. HoloTC correlated strongly with total cobalamin (r=0.69, P<0.001), weaker with eGFR(creatinine) (r=-0.09, P<0.05) and creatinine (r=0.09, P<0.05), the latter correlation was only seen in subjects with creatinine <100 mu mol/L. HoloTC correlated negatively with plasma total homocysteine (r=-0.24, P<0.001), but not with cystatin C and age. Conclusions Serum holoTC in healthy elderly men shows the same distribution as earlier described for a younger reference population. In this group of elderly subjects, holoTC did not correlate to reduced renal function. Thus, holoTC appears to be a promising tool for evaluating cobalamin status also in elderly populations.
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| 12. |
- Loh, Tze Ping, et al.
(author)
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The LEAP checklist for laboratory evaluation and analytical performance characteristics reporting of clinical measurement procedures
- 2024
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In: Annals of Clinical Biochemistry. - : Sage Publications. - 0004-5632 .- 1758-1001. ; 61:1, s. 3-7
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Journal article (peer-reviewed)abstract
- Reporting a measurement procedure and its analytical performance following method evaluation in a peer-reviewed journal is an important means for clinical laboratory practitioners to share their findings. It also represents an important source of evidence base to help others make informed decisions about their practice. At present, there are significant variations in the information reported in laboratory medicine journal publications describing the analytical performance of measurement procedures. These variations also challenge authors, readers, reviewers and editors in deciding the quality of a submitted manuscript. The International Federation of Clinical Chemistry and Laboratory Medicine Working Group on Method Evaluation Protocols (IFCC WG-MEP) developed a checklist and recommends its adoption to enable a consistent approach to reporting method evaluation and analytical performance characteristics of measurement procedures in laboratory medicine journals. It is envisioned that the LEAP checklist will improve the standardisation of journal publications describing method evaluation and analytical performance characteristics, improving the quality of the evidence base that is relied upon by practitioners.
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| 13. |
- Maghsoodi, N., et al.
(author)
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Elevated fasting and postprandial C-terminal telopeptide after Roux-en-Y gastric bypass
- 2017
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In: Annals of Clinical Biochemistry. - : SAGE Publications. - 0004-5632. ; 54:4, s. 495-500
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Journal article (peer-reviewed)abstract
- Background Roux-en-Y gastric bypass increases circulating bile acid concentrations, known mediators of postprandial suppression of markers of bone resorption. Long-term data, however, indicate that Roux-en-Y gastric bypass confers an increased risk of bone loss on recipients. Methods Thirty-six obese individuals, median age 44 (26-64) with median body mass index at baseline of 42.5 (40.4-46) were studied before and 15 months after Roux-en-Y gastric bypass. After an overnight fast, patients received a 400kcal mixed meal. Blood samples were collected premeal then at 30-min periods for 120min. Pre and postmeal samples were analysed for total bile acids, parathyroid hormone and C-terminal telopeptide. Results Body weight loss post Roux-en-Y gastric bypass was associated with a median 4.9-fold increase in peak postprandial total bile acid concentration, and a median 2.4-fold increase in cumulative food evoked bile acid response. Median fasting parathyroid hormone, postprandial reduction in parathyroid hormone and total parathyroid hormone release over 120min remained unchanged after surgery. After surgery, median fasting C-terminal telopeptide increased 2.3-fold, peak postprandial concentrations increased 3.8-fold and total release was increased 1.9-fold. Conclusions Fasting and postprandial total bile acids and C-terminal telopeptide are increased above reference range after Roux-en-Y gastric bypass. These changes occur in spite of improved vitamin D status with supplementation. These results suggest that post-Roux-en-Y gastric bypass increases in total bile acids do not effectively oppose an ongoing resorptive signal operative along the gut-bone axis. Serial measurement of C-terminal telopeptide may be of value as a risk marker for long-term skeletal pathology in patients post Roux-en-Y gastric bypass.
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| 14. |
- Marriott, L, et al.
(author)
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Analysis of urinary human chorionic gonadotrophin concentrations in normal and failing pregnancies using longitudinal, Cox proportional hazards and two-stage modelling
- 2017
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In: Annals of clinical biochemistry. - : SAGE Publications. - 1758-1001. ; 54:5, s. 548-557
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Journal article (peer-reviewed)abstract
- Human chorionic gonadotrophin is a marker of early pregnancy. This study sought to determine the possibility of being able to distinguish between healthy and failing pregnancies by utilizing patient-associated risk factors and daily urinary human chorionic gonadotrophin concentrations. Methods Data were from a study that collected daily early morning urine samples from women trying to conceive (n = 1505); 250 of whom became pregnant. Data from 129 women who became pregnant (including 44 miscarriages) were included in these analyses. A longitudinal model was used to profile human chorionic gonadotrophin, a Cox proportional hazards model to assess demographic/menstrual history data on the time to failed pregnancy, and a two-stage model to combine these two models. Results The profile for log human chorionic gonadotrophin concentrations in women suffering miscarriage differs to that of viable pregnancies; rate of human chorionic gonadotrophin rise is slower in those suffering a biochemical loss (loss before six weeks, recognized by a rise and fall of human chorionic gonadotrophin) and tends to plateau at a lower log human chorionic gonadotrophin in women suffering an early miscarriage (loss six weeks or later), compared with viable pregnancies. Maternal age, longest cycle length and time from luteinizing hormone surge to human chorionic gonadotrophin reaching 25 mIU/mL were found to be significantly associated with miscarriage risk. The two-stage model found that for an increase of one day in the time from luteinizing hormone surge to human chorionic gonadotrophin reaching 25 mIU/mL, there is a 30% increase in miscarriage risk (hazard ratio: 1.30; 95% confidence interval: 1.04, 1.62). Conclusion Rise of human chorionic gonadotrophin in early pregnancy could be useful to predict pregnancy viability. Daily tracking of urinary human chorionic gonadotrophin may enable early identification of some pregnancies at risk of miscarriage.
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| 15. |
- Verwey, N A, et al.
(author)
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A worldwide multicentre comparison of assays for cerebrospinal fluid biomarkers in Alzheimer's disease.
- 2009
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In: Annals of clinical biochemistry. - : SAGE Publications. - 0004-5632 .- 1758-1001. ; 46:Pt 3, s. 235-40
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Journal article (peer-reviewed)abstract
- BACKGROUND: Different cerebrospinal fluid (CSF) amyloid-beta 1-42 (Abeta(1-42)), total Tau (Tau) and Tau phosphorylated at threonine 181 (P-Tau) levels are reported, but currently there is a lack of quality control programmes. The aim of this study was to compare the measurements of these CSF biomarkers, between and within centres. METHODS: Three CSF-pool samples were distributed to 13 laboratories in 2004 and the same samples were again distributed to 18 laboratories in 2008. In 2004 six laboratories measured Abeta(1-42), Tau and P-Tau and seven laboratories measured one or two of these marker(s) by enzyme-linked immunosorbent assays (ELISAs). In 2008, 12 laboratories measured all three markers, three laboratories measured one or two marker(s) by ELISAs and three laboratories measured the markers by Luminex. RESULTS: In 2004, the ELISA intercentre coefficients of variance (interCV) were 31%, 21% and 13% for Abeta(1-42), Tau and P-Tau, respectively. These were 37%, 16% and 15%, respectively, in 2008. When we restricted the analysis to the Innotest (N = 13) for Abeta(1-42), lower interCV were calculated (22%). The centres that participated in both years (N = 9) showed interCVs of 21%, 15% and 9% and intra-centre coefficients (intraCV) of variance of 25%,18% and 7% in 2008. CONCLUSIONS: The highest variability was found for Abeta(1-42). The variabilities for Tau and P-Tau were lower in both years. The centres that participated in both years showed a high intraCV comparable to their interCV, indicating that there is not only a high variation between but also within centres. Besides a uniform standardization of (pre)analytical procedures, the same assay should be used to decrease the inter/intracentre variation.
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| 16. |
- Vincent, Royce P, et al.
(author)
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Higher circulating bile acid concentrations in obese patients with type 2 diabetes.
- 2013
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In: Annals of clinical biochemistry. - : SAGE Publications. - 1758-1001. ; 50:Pt 4, s. 360-4
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Journal article (peer-reviewed)abstract
- Bile acids (BAs) play an important role in releasing incretin hormones via the enteroendocrine L-cell surface TGR5 receptors. The aim of this study was to investigate the difference in BA concentration at baseline and in response to a meal stimulus between type 2 diabetes mellitus (T2DM) and a matched normoglycaemic group.
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