Comparison of a two-step Tempus600 hub solution single-tube vs. container-based, one-step pneumatic transport system.

OBJECTIVES: Efficient and timely transportation of clinical samples is pivotal to ensure accurate diagnoses and effective patient care. During the transportation process, preservation of sample integrity is crucial to avoid pre-analytical aberrations on laboratory results. Here, we present a comparative analysis between a two-step Tempus600 hub solution single-tube and a one-step, container-based pneumatic transport system (PTS) from Airco, for the in-house transportation of blood samples. METHODS: Ten blood samples from healthy volunteers were split in 10 mL collection tubes filled at full or half capacity for transportation with the two PTS (about 250 m). To compare the impact of transportation, markers of hemolysis such as lactate dehydrogenase (LDH), potassium (K+), and the hemolysis index (HI), were determined. Additionally, differences in HI in routine samples and repeated transportation was investigated. To assess and compare the mechanistic impact profiles, we recorded the acceleration profiles of the two PTS using a shock data logger. RESULTS: Transportation using the Tempus600 hub solution resulted in 49 and 46 % higher HI with samples filled to total or half capacity, respectively. Routine samples transported with the Tempus600 hub solution showed a higher median HI by 23 and 33 %. Additionally, shock logger analysis showed an elevated amount of shocks (6.5 fold) and shock intensities (1.8 fold). CONCLUSIONS: The Tempus600 hub solution caused an increased number of unreportable LDH or K+ results based on the hemolysis index. However, it was only statistically significant for LDH (p<0.01 and p<0.08) - while the comparisons for K+ were not statistically significant (p<0.28 and p<0.56).

Novel plasma biomarkers predicting biventricular involvement in arrhythmogenic right ventricular cardiomyopathy.

BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited heart muscle disease characterized by fibrofatty replacement of the myocardium and ventricular arrhythmias. Biventricular involvement in ARVC may lead to heart failure. This study aimed to investigate the role of plasma biomarkers soluble (s)ST2, Galectin-3 (Gal-3) and GDF-15 in predicting biventricular involvement and adverse outcomes in ARVC. METHODS AND RESULTS: ARVC patients from 2 independent cohorts, were studied. The Bejing (Chinese) cohort (n = 108) was the discovery cohort, whereas the Zurich (Swiss) cohort (n = 47) served as validation. All patients had a definite ARVC diagnosis at time of blood withdrawal. Biomarkers were independently correlated with NT-proBNP and left ventricular (LV)-function. ARVC patients with LV involvement had higher levels of sST2 and GDF-15 as compared to controls and patients with isolated right ventricle (RV) involvement. sST2 and GDF-15 were significantly correlated with late gadolinium enhancement in CMR and with adverse heart failure outcomes. Gal-3 was elevated in ARVC patients with and without LV involvement. The combined use of the three biomarkers (sST2, GDF-15 and NT-proBNP) showed the best performance in predicting LV involvement in both cohorts. Plasma drawn from the coronary arteries and coronary sinus indicated a transmyocardial elevation of sST2, but no transmyocardial gradient of GDF-15. After heart transplantation, both sST2 and GDF-15 returned to near-normal levels. CONCLUSION: Our study showed that sST2 and GDF-15 may predict biventricular involvement in ARVC. The combined use of sST2, GDF-15 and NT-proBNP showed the best prediction of biventricular involvement in ARVC.

Effect of Alirocumab Added to High-Intensity Statin Therapy on Coronary Atherosclerosis in Patients With Acute Myocardial Infarction: The PACMAN-AMI Randomized Clinical Trial.

Importance: Coronary plaques that are prone to rupture and cause adverse cardiac events are characterized by large plaque burden, large lipid content, and thin fibrous caps. Statins can halt the progression of coronary atherosclerosis; however, the effect of the proprotein convertase subtilisin kexin type 9 inhibitor alirocumab added to statin therapy on plaque burden and composition remains largely unknown. Objective: To determine the effects of alirocumab on coronary atherosclerosis using serial multimodality intracoronary imaging in patients with acute myocardial infarction. Design, Setting, and Participants: The PACMAN-AMI double-blind, placebo-controlled, randomized clinical trial (enrollment: May 9, 2017, through October 7, 2020; final follow-up: October 13, 2021) enrolled 300 patients undergoing percutaneous coronary intervention for acute myocardial infarction at 9 academic European hospitals. Interventions: Patients were randomized to receive biweekly subcutaneous alirocumab (150 mg; n = 148) or placebo (n = 152), initiated less than 24 hours after urgent percutaneous coronary intervention of the culprit lesion, for 52 weeks in addition to high-intensity statin therapy (rosuvastatin, 20 mg). Main Outcomes and Measures: Intravascular ultrasonography (IVUS), near-infrared spectroscopy, and optical coherence tomography were serially performed in the 2 non-infarct-related coronary arteries at baseline and after 52 weeks. The primary efficacy end point was the change in IVUS-derived percent atheroma volume from baseline to week 52. Two powered secondary end points were changes in near-infrared spectroscopy-derived maximum lipid core burden index within 4 mm (higher values indicating greater lipid content) and optical coherence tomography-derived minimal fibrous cap thickness (smaller values indicating thin-capped, vulnerable plaques) from baseline to week 52. Results: Among 300 randomized patients (mean [SD] age, 58.5 [9.7] years; 56 [18.7%] women; mean [SD] low-density lipoprotein cholesterol level, 152.4 [33.8] mg/dL), 265 (88.3%) underwent serial IVUS imaging in 537 arteries. At 52 weeks, mean change in percent atheroma volume was -2.13% with alirocumab vs -0.92% with placebo (difference, -1.21% [95% CI, -1.78% to -0.65%], P < .001). Mean change in maximum lipid core burden index within 4 mm was -79.42 with alirocumab vs -37.60 with placebo (difference, -41.24 [95% CI, -70.71 to -11.77]; P = .006). Mean change in minimal fibrous cap thickness was 62.67 µm with alirocumab vs 33.19 µm with placebo (difference, 29.65 µm [95% CI, 11.75-47.55]; P = .001). Adverse events occurred in 70.7% of patients treated with alirocumab vs 72.8% of patients receiving placebo. Conclusions and Relevance: Among patients with acute myocardial infarction, the addition of subcutaneous biweekly alirocumab, compared with placebo, to high-intensity statin therapy resulted in significantly greater coronary plaque regression in non-infarct-related arteries after 52 weeks. Further research is needed to understand whether alirocumab improves clinical outcomes in this population. Trial Registration: ClinicalTrials.gov Identifier: NCT03067844.

European multicenter evaluation of Xpert® Xpress SARS-CoV-2/Flu/RSV test.

Rapid diagnostics for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are paramount for reducing the spread of the current pandemic. During additional seasonal epidemics with influenza A/B and respiratory syncytial virus (RSV), the clinical signs and symptoms cannot be distinguished easily from SARS-CoV-2. Therefore, a new assay combining four targets in the form of the new Xpert Xpress SARS-CoV-2/Flu/RSV assay was evaluated. The assay was compared to the Xpert Xpress SARS-CoV-2, Xpert Xpress Flu/RSV, Seegene Flu/RSV, influenza A/B r-gene® and RSV/hMPV r-gene®. A total of 295 nasopharyngeal and throat swabs were tested at four institutes throughout Europe including 72 samples positive for SARS-CoV-2, 65 for influenza A, 47 for influenza B, and 77 for RSV. The sensitivity of the new assay was above 95% for all targets, with the highest for SARS-CoV-2 (97.2%). The overall correlation of SARS-CoV-2 Ct values between Xpert Xpress SARS-CoV-2 assay and Xpert Xpress SARS-CoV-2/Flu/RSV assay was high. The agreement between Ct values above 30 showed the multiplex giving higher Ct values for SARS-CoV-2 on average than the singleplex assay. In conclusion, the new assay is a rapid and reliable alternative with less hands-on time for the detection of not one, but four upper respiratory tract pathogens that may circulate at the same time.

Cognitive function in association with high estradiol levels resulting from fertility treatment.

The putative association between hormones and cognitive performance is controversial. While there is evidence that estradiol plays a neuroprotective role, hormone treatment has not been shown to improve cognitive performance. Current research is flawed by the evaluation of combined hormonal effects throughout the menstrual cycle or in the menopausal transition. The stimulation phase of a fertility treatment offers a unique model to study the effect of estradiol on cognitive function. This quasi-experimental observational study is based on data from 44 women receiving IVF in Zurich, Switzerland. We assessed visuospatial working memory, attention, cognitive bias, and hormone levels at the beginning and at the end of the stimulation phase of ovarian superstimulation as part of a fertility treatment. In addition to inter-individual differences, we examined intra-individual change over time (within-subject effects). The substantial increases in estradiol levels resulting from fertility treatment did not relate to any considerable change in cognitive functioning. As the tests applied represent a broad variety of cognitive functions on different levels of complexity and with various brain regions involved, we can conclude that estradiol does not show a significant short-term effect on cognitive function.

Vitamin D deficiency is common in kidney transplant recipients, but is not associated with infections after transplantation.

The relevance of vitamin D for infections after kidney transplantation is poorly defined. 25-OH vitamin D (25-OHD) levels of 135 kidney transplant recipients, enrolled in the Swiss Transplant Cohort Study, were determined peri-transplant and 6 months post-transplant. Logistic regression was used to address the associations of 25-OHD and overall infections and bacterial infections, respectively. For the first 6 months post-transplant, 25-OHD peri-transplant, and for the second period (after 6 to 30 months post-transplant), 25-OHD at 6 months post-transplant was considered. Vitamin D deficiency was common peri-transplant and remained highly prevalent 6 months after transplantation despite frequent supplementation. Median 25-OHD levels increased from 12.0 ng/mL (IQR 5.3-19.5) peri-transplant to 16.5 ng/mL (IQR 10.6-22.6) 6 months post-transplant (P = .005). We did not detect a significant association between 25-OHD and overall infections (adjusted odds ratio (aOR) 1.05, 95% confidence interval (95%CI) 0.44-2.51; aOR 0.67, 95%CI 0.31-1.43) or bacterial infections (aOR 0.79, 95%CI 0.32-1.96; aOR 0.79, 95%CI 0.35-1.75) for the first and second period. To conclude, at both time points, vitamin D deficiency was observed in more than 50% of kidney recipients, albeit an increase in 25-OHD in the longitudinal course was observed. No significant association between 25-OHD and infections was detected.

Predictive Power of Bone Turnover Biomarkers to Estimate Bone Mineral Density after Kidney Transplantation with or without Denosumab: A post hoc Analysis of the POSTOP Study.

BACKGROUND: Low bone mineral density (BMD) represents a major risk factor for bone fractures in patients with chronic kidney disease (CKD) as well as after kidney transplantation. However, modalities to solidly predict patients at fracture risk are yet to be defined. Better understanding of bone turnover biomarkers (BTMs) may close this diagnostic gap. This study strives to correlate BTMs to BMD in kidney transplant recipients. METHODS: Changes in BTMs - procollagen type I N-terminal propeptide (P1NP), bone-specific alkaline phosphatase (BSAP), ß-isomer of the C-terminal telopeptide of type I collagen, and urine deoxypyridinoline/Cr - at the time of transplant and 3 months were correlated to changes in BMD measured by dual-energy X-ray absorptiometry at the time of transplant, 6, and 12 months, respectively. Half of the collective was treated with denosumab twice yearly in addition to the standard treatment with calcium and vitamin D. RESULTS: Changes in bone formation markers BSAP and P1NP within 3 months showed a significant negative correlation to changes in BMD at the hip within 6 months in denosumab-naïve patients. This correlation was abrogated by denosumab treatment. CONCLUSIONS: Changes in BSAP and P1NP showed promise in short-term prediction of BMD. We suggest further trials expanding on the knowledge of these BTMs with assessment of fracture risk, sequential measurements of BTMs within the first 6 months, and the additional use of computed tomography to assess BMD.

Vitamin D status and risk of infections after liver transplantation in the Swiss Transplant Cohort Study.

Increasing evidence indicates a role of vitamin D in the immune system affecting response to infections. We aimed to characterize the role of vitamin D status, i.e. deficiency [25-OH vitamin D (25-OHD) <50 nmol/l] and no deficiency (25-OHD ≥50 nmol/l) in incident infections after liver transplantation. In 135 liver transplant recipients, blood samples drawn at time of liver transplantation and 6 months afterwards were used to determine 25-OHD levels. Incident infections episodes were prospectively collected within the Swiss Transplant Cohort Study database. Poisson regression was applied to address associations between vitamin D status and incident infections. Vitamin D deficiency was common at time of transplantation and 6 months afterwards without a significant change in median 25-OHD levels. In univariable analyses, vitamin D deficiency was a risk factor for incident infections in the first 6 months post-transplant incidence rate ratio (IRR 1.52, 95% CI 1.08-2.15, P = 0.018) and for bacterial infections occurring after 6 up to 30 months post-transplant (IRR 2.29, 95% CI 1.06-4.94, P = 0.034). These associations were not detectable in multivariable analysis with adjustment for multiple confounders. Efforts to optimize vitamin D supplementation in liver transplant recipients are needed. Our data question the role of vitamin D deficiency in incident infections.

Treatment of non-alcoholic steatohepatitis patients with vitamin D: a double-blinded, randomized, placebo-controlled pilot study.

BACKGROUND: Non-alcoholic steatohepatitis (NASH) is defined by liver inflammation and consecutive fibrotic damage caused by a deposition of fat in the liver. No licensed medical treatments exist and lifestyle modification is difficult to incorporate into everyday life. We investigated the efficacy and safety of a 48-week treatment with vitamin D3 in NASH patients. METHODS: Histologically determined NASH patients with elevated alanine aminotransferase (ALT) and decreased 25-OH vitamin D level at baseline received vitamin D3 or placebo orally over a 48-week period. The primary endpoint of this study was the change in ALT from baseline to the end-of-treatment. Steatohepatitis was categorized according to the Steatosis, Activity and Fibrosis Score and disease activity was assessed using the NAFLD activity score. RESULTS: Serum 25-OH vitamin D levels significantly increased only in the vitamin D3 group over the 48-week treatment phase indicating compliance. In contrast to placebo, patients in the vitamin D group had markedly decreased ALT levels after the end-of-treatment phase. A significant decrease during treatment with vitamin D was also observed for cytokeratin-18 fragments compared with placebo. The study was not powered to detect changes in histological score, hence only descriptive results for histopathological characteristics are available. CONCLUSIONS: Treatment with 2100 IE vitamin D q.d. over 48 weeks was well tolerated and led to a significant improvement of serum ALT levels in patients with hypovitaminosis D and histology-proven NASH as the primary endpoint together with a trend toward reduction of hepatic steatosis, which was not significant due to a small number of available biopsy specimens.

Prevalence and causes of abnormal PSA recovery.

BACKGROUND: Prostate-specific antigen (PSA) test is of paramount importance as a diagnostic tool for the detection and monitoring of patients with prostate cancer. In the presence of interfering factors such as heterophilic antibodies or anti-PSA antibodies the PSA test can yield significantly falsified results. The prevalence of these factors is unknown. METHODS: We determined the recovery of PSA concentrations diluting patient samples with a standard serum of known PSA concentration. Based on the frequency distribution of recoveries in a pre-study on 268 samples, samples with recoveries <80% or >120% were defined as suspect, re-tested and further characterized to identify the cause of interference. RESULTS: A total of 1158 consecutive serum samples were analyzed. Four samples (0.3%) showed reproducibly disturbed recoveries of 10%, 68%, 166% and 4441%. In three samples heterophilic antibodies were identified as the probable cause, in the fourth anti-PSA-autoantibodies. The very low recovery caused by the latter interference was confirmed in serum, as well as heparin- and EDTA plasma of blood samples obtained 6 months later. Analysis by eight different immunoassays showed recoveries ranging between <10% and 80%. In a follow-up study of 212 random plasma samples we found seven samples with autoantibodies against PSA which however did not show any disturbed PSA recovery. CONCLUSIONS: About 0.3% of PSA determinations by the electrochemiluminescence assay (ECLIA) of Roche diagnostics are disturbed by heterophilic or anti-PSA autoantibodies. Although they are rare, these interferences can cause relevant misinterpretations of a PSA test result.

Evaluation of the new restandardized Abbott Architect 25-OH Vitamin D assay in vitamin D-insufficient and vitamin D-supplemented individuals.

BACKGROUND: Recently, Abbott Diagnostics has restandardized the Architect 25(OH)D assay against the NIST SRM 2972. We have evaluated the analytical and clinical performance of the restandardized Architect 25(OH)D assay and compared its performance with a NIST-traceable liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and the Roche total 25(OH)D assay in vitamin D-insufficient individuals before and after vitamin D3 supplementation. METHODS: Frozen serum samples were obtained from 88 healthy subjects with self-perceived fatigue and vitamin D-insufficiency <50 nmol L-1 who were randomized to receive a single 100 000 IU dose of vitamin D3 (n = 48) or placebo (n = 40). Total 25(OH)D concentrations were measured before and 4 weeks after supplementation by the restandardized Architect 25(OH)D assay, LC-MS/MS, and Roche assay. RESULTS: The Architect 25(OH)D assay showed an intra- and inter-assay imprecision of <5%. Comparison of the Architect assay with the LC-MS/MS method showed a good correlation in both vitamin D-insufficient and vitamin D-supplemented subjects, however, with a negative mean bias of 17.4% and 8.9%, respectively. As compared to the Roche assay, the Abbott assay underestimated 25(OH)D results in insufficient subjects (<50 nmol L-1 ) with a mean negative bias of 17.1%, this negative bias turned into a positive bias in supplemented subjects. Overall there was a moderate agreement in classification of vitamin D-insufficient and -supplemented individuals into different vitamin D states between the Architect 25(OH)D method and LC-MS/MS. CONCLUSION: The routine use of the restandardized Architect 25(OH)D results in a slight underestimation of circulating total 25(OH)D levels at lower concentrations and thus potential misclassification of vitamin D status.

Impact of a single oral dose of 100,000 IU vitamin D3 on profiles of serum 25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and 1,25(OH)2D3 in adults with vitamin D insufficiency.

BACKGROUND: We investigate the effect of a high dose of vitamin D3 on circulating concentrations of 25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and 1,25(OH)2D3 in healthy individuals with self-perceived fatigue and vitamin D insufficiency [25(OH)D3<50 nmol/L]. METHODS: One hundred and seven study participants (age 20-50 years) were randomized to receive a single 100,000 IU dose of vitamin D3 (n=52) or placebo (n=55). Vitamin D metabolite concentrations in serum were measured before, and 4 weeks after, supplementation. RESULTS: Overall, 52% of participants receiving vitamin D3 attained a serum 25(OH)D3 level >75 nmol/L. Among individuals who received vitamin D3, there were significant increases in serum concentrations of 25(OH)D3 and its metabolites 24,25(OH)2D3, 3-epi-25(OH)D3, and 1,25(OH)2D3 at 4 weeks; however, inter-individual variability in these changes was substantial. Positive correlations between serum 25(OH)D3 and 24,25(OH)2D3 and 3-epi-25(OH)D3, and a significant negative correlation between serum 1,25(OH)2D3 and 3-epi-25(OH)D3, were found 4 weeks after supplementation. The 24,25(OH)2D3/25(OH)D3 and 24,25(OH)2D3/1,25(OH)2D3 ratios were significantly increased, compared with baseline, in participants receiving vitamin D3. Baseline 25(OH)D3 concentration was the only factor predictive of the change in 25(OH)D3 after supplementation. CONCLUSIONS: Administration of a single high dose of vitamin D3 leads to a significant increase in concentrations of 25(OH)D3, 24,25(OH)2D3, 3-epi-25(OH)D3 and 1,25(OH)2D3; induction of the catabolic pathway predominates over the production of 1,25(OH)2D3. Due to the high inter-individual variation in the 25(OH)D3 response to supplementation, any given dose of vitamin D is unlikely to achieve optimal vitamin D status in all treated individuals.

Association between tuberculosis, diabetes and 25 hydroxyvitamin D in Tanzania: a longitudinal case control study.

BACKGROUND: Vitamin D level is inversely associated with tuberculosis (TB) and diabetes (DM). Vitamin D could be a mediator in the association between TB and DM. We examined the associations between vitamin D, TB and DM. METHODS: Consecutive adults with TB and sex- and age-matched volunteers were included in a case-control study in Dar es Salaam, Tanzania. Glycemia and total vitamin D (25(OH)D) were measured at enrolment and after TB treatment in cases. The association between low 25(OH)D (<75 nmol/l) and TB was evaluated by logistic regression adjusted for age, sex, body mass index, socioeconomic status, sunshine hours, HIV and an interaction between low 25(OH)D and hyperglycemia. RESULTS: The prevalence of low 25(OH)D was similar in TB patients and controls (25.8 % versus 31.0 %; p = 0.22). In the subgroup of patients with persistent hyperglycemia (i.e. likely true diabetic patients), the proportion of patients with low 25(OH)D tended to be greater in TB patients (50 % versus 29.7 %; p = 0.20). The effect modification by persistent hyperglycemia persisted in the multivariate analysis (pinteraction = 0.01). CONCLUSIONS: Low 25(OH)D may increase TB risk in patients with underlying DM. Trials should examine if this association is causal and whether adjunct vitamin D therapy is beneficial in this population.

Analytical and clinical performance of the new Fujirebio 25-OH vitamin D assay, a comparison with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and three other automated assays.

BACKGROUND: We evaluated the analytical and clinical performance of the new Lumipulse® G 25-OH vitamin D assay from Fujirebio, and compared it to a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method and three other commercial automated assays. METHODS: Total 25 hydroxy vitamin D (25(OH)D) levels were measured in 100 selected serum samples from our routine analysis with Fujirebio 25(OH)D assay. The results were compared with those obtained with LC-MS/MS and three other automated 25(OH)D assays (Abbott, Beckman, and Roche). The accuracy of each assay tested was evaluated against a Labquality reference serum panel for 25(OH)D (Ref!25OHD; University of Ghent). RESULTS: Intra- and inter-day imprecision of the Fujirebio 25(OH)D assay was <5%. Fujirebio 25(OH)D assay showed the highest correlation among the assays tested with the LC-MS/MS method (R=0.986). The mean relative bias obtained was -15.6% (Fujirebio), -12.7% (Beckman), -2.1% (Abbott) and 9.7% (Roche) as compared to LC-MS/MS. Comparison with the Labquality certified reference serum panel yielded a mean bias of -11.8% (Fujirebio), -14.1% (Beckman), 4.4% (Abbott) and 3.2% (Roche), respectively. Compared to LC-MS/MS, the sensitivity of different methods in detecting vitamin D insufficiency (<50 nmol/L) varied from 100% for the Fujirebio assay to 72.7% for Roche, and specificity ranged from 94.4% for Roche to 87.6% for Beckman. CONCLUSIONS: The Lumipulse G 25-OH vitamin D assay from Fujirebio demonstrated a good correlation with LC-MS/MS and some immunoassays. The performance of the assay is well-suited for routine 25(OH)D measurement in clinical serum samples. A correction for the observed negative bias vs. LC-MS/MS could be considered.

Head to head evaluation of the analytical performance of two commercial methotrexate immunoassays and comparison with liquid chromatography-mass spectrometry and the former fluorescence polarization immunoassay.

BACKGROUND: Monitoring of plasma drug levels is mandatory in patients receiving high-dose methotrexate. This study evaluated the analytical performance of the novel Architect and the established ARK™ methotrexate immunoassay (running on the Roche Cobas© c502 analyzer) in comparison with liquid chromatography-mass spectrometry (LC-MS) and the TDx/TDxFLx Methotrexate II assay. METHODS: Imprecision and linearity were verified for the Architect and ARK assay according to CLSI EP15-A3 and EP6-A guidelines, respectively. The reported limit of quantitation (0.04 µmol/L) was tested for both assays according to the CLSI EP17-A2 guideline. Correlation and agreement between the different assays were evaluated using residual plasma samples (n=153). RESULTS: Total imprecision was <6.3% and <9.5% for the Architect and ARK assay, respectively. The claimed linearity and limit of quantitation were confirmed for the Architect assay. For the ARK assay, imprecision at the limit of quantitation was <18% with a positive bias resulting in a high total error up to 58%, and hence the linearity could not be confirmed. Both assays showed strong correlations with the TDX assay and LC-MS but a positive bias of 12.2% and 20.5% in comparison to LC-MS for the Architect and ARK assay, respectively. For the ARK assay this bias increased dramatically for samples with concentrations towards the limit of quantitation. CONCLUSIONS: The Architect assay is suitable for monitoring plasma methotrexate, but the ARK assay showed unsatisfactory performance in the analysis of low concentrated samples. Unlike the TDX assay, both assays require manual dilution of samples at higher concentrations, which delays sample processing in clinical routine.

Reference intervals for 24 laboratory parameters determined in 24-hour urine collections.

BACKGROUND: Reference intervals for many laboratory parameters determined in 24-h urine collections are either not publicly available or based on small numbers, not sex specific or not from a representative sample. METHODS: Osmolality and concentrations or enzymatic activities of sodium, potassium, chloride, glucose, creatinine, citrate, cortisol, pancreatic α-amylase, total protein, albumin, transferrin, immunoglobulin G, α1-microglobulin, α2-macroglobulin, as well as porphyrins and their precursors (δ-aminolevulinic acid and porphobilinogen) were determined in 241 24-h urine samples of a population-based cohort of asymptomatic adults (121 men and 120 women). For 16 of these 24 parameters creatinine-normalized ratios were calculated based on 24-h urine creatinine. The reference intervals for these parameters were calculated according to the CLSI C28-A3 statistical guidelines. RESULTS: By contrast to most published reference intervals, which do not stratify for sex, reference intervals of 12 of 24 laboratory parameters in 24-h urine collections and of eight of 16 parameters as creatinine-normalized ratios differed significantly between men and women. For six parameters calculated as 24-h urine excretion and four parameters calculated as creatinine-normalized ratios no reference intervals had been published before. For some parameters we found significant and relevant deviations from previously reported reference intervals, most notably for 24-h urine cortisol in women. Ten 24-h urine parameters showed weak or moderate sex-specific correlations with age. CONCLUSIONS: By applying up-to-date analytical methods and clinical chemistry analyzers to 24-h urine collections from a large population-based cohort we provide as yet the most comprehensive set of sex-specific reference intervals calculated according to CLSI guidelines for parameters determined in 24-h urine collections.

N-terminal pro-B-type natriuretic peptide-ratio predicts mortality after transcatheter aortic valve replacement.

OBJECTIVES: We studied the prognostic value of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP)-ratio, which is independent of individual cutoff levels, in predicting mortality in patients undergoing transcatheter aortic valve replacement (TAVR). BACKGROUND: Elevated levels of natriuretic peptides are associated with adverse outcomes across a wide spectrum of cardiovascular diseases. However, cutoff values differ according to age, gender, and body weight. METHODS: 244 TAVR patients with preprocedural NT-proBNP levels were analyzed, and the predictive value of NT-proBNP-ratio (measured NT-proBNP/maximal normal NT-proBNP values specific for age and gender) on all-cause-mortality was assessed in a multivariate model. RESULTS: Median NT-proBNP-ratio was 4.2 [IQR 1.8-9.7]. All-cause mortality at 30 days was 3.4% in patients with less than median NT-proBNP-ratio, and 14.0% in patients with more than median NT-proBNP-ratio (P=0.02). All-cause mortality at 1 year was 8.5% in patients with less than median NT-proBNP-ratio, and 32.1% in those with more than median NT-proBNP-ratio (P=0.001). Cumulative survival declined with increasing quartiles of NT-proBNP-ratio (log rank P=0.001). All patients with a NT-proBNP-ratio below 1.5 survived at 1-year follow-up. In ROC analysis, NT-proBNP-ratio significantly predicted 30-day (AUC=0.72; P=0.002) and 1-year all-cause mortality (AUC=0.72; P<0.001). By multivariate Cox regression analysis, NT-proBNP-ratio, chronic obstructive pulmonary disease, and serum creatinine were the only independent predictors of all-cause mortality. CONCLUSIONS: Elevated NT-proBNP-ratio was associated with increased short- and long-term mortality after TAVR, and independently predicted all-cause mortality. NT-proBNP-ratio should be considered in the risk stratification of patients undergoing TAVR.

Robot-assisted training for heart failure patients - a small pilot study.

OBJECTIVE: The objective of this study was assess robot-assisted gait therapy with the Lokomat® system in heart failure patients. METHODS: Patients (n = 5) with stable heart failure and a left ventricular ejection fraction of less than 45% completed a four-week aerobic training period with three trainings per week and an integrated dynamic resistance training of the lower limbs. Patients underwent testing of cardiac and inflammatory biomarkers. A cardiopulmonary exercise test, a quality of life score and an evaluation of the muscular strength by measuring the peak quadriceps force was performed. RESULTS: No adverse events occurred. The combined training resulted in an improvement in peak work rate (range: 6% to 36%) and peak quadriceps force (range: 3% to 80%) in all participants. Peak oxygen consumption (range: ­3% to + 61%) increased in three, and oxygen pulse (range: ­7% to + 44%) in four of five patients. The quality of life assessment indicated better well-being in all participants. NT-ProBNP (+233 to ­733 ng/ml) and the inflammatory biomarkers (hsCRP and IL6) decreased in four of five patients (IL 6: +0.5 to ­2 mg/l, hsCRP: +0.2 to ­6.5 mg/l). CONCLUSIONS: Robot-assisted gait therapy with the Lokomat® System is feasible in heart failure patients and was safe in this trial. The combined aerobic and resistance training intervention with augmented feedback resulted in benefits in exercise capacity, muscle strength and quality of life, as well as an improvement of cardiac (NT-ProBNP) and inflammatory (IL6, hsCRP) biomarkers. Results can only be considered as preliminary and need further validation in larger studies. (ClinicalTrials.gov number, NCT 02146196)

Renal expression of FGF23 and peripheral resistance to elevated FGF23 in rodent models of polycystic kidney disease.

Fibroblast growth factor 23 (FGF23) regulates phosphate homeostasis and is linked to cardiovascular disease and all-cause mortality in chronic kidney disease. FGF23 rises in patients with CKD stages 2-3, but in patients with autosomal dominant polycystic kidney disease, the increase of FGF23 precedes the first measurable decline in renal function. The mechanisms governing FGF23 production and effects in kidney disease are largely unknown. Here we studied the relation between FGF23 and mineral homeostasis in two animal models of PKD. Plasma FGF23 levels were increased 10-fold in 4-week-old cy/+ Han:SPRD rats, whereas plasma urea and creatinine concentrations were similar to controls. Plasma calcium and phosphate levels as well as TmP/GFR were similar in PKD and control rats at all time points examined. Expression and activity of renal phosphate transporters, the vitamin D3-metabolizing enzymes, and the FGF23 co-ligand Klotho in the kidney were similar in PKD and control rats through 8 weeks of age, indicating resistance to FGF23, although phosphorylation of the FGF receptor substrate 2α protein was enhanced. In the kidneys of rats with PKD, FGF23 mRNA was highly expressed and FGF23 protein was detected in cells lining renal cysts. FGF23 expression in bone and spleen was similar in control rats and rats with PKD. Similarly, in an inducible Pkd1 knockout mouse model, plasma FGF23 levels were elevated, FGF23 was expressed in kidneys, but renal phosphate excretion was normal. Thus, the polycystic kidney produces FGF23 but is resistant to its action.

Quantification of teicoplanin in plasma by LC-MS with online sample clean-up and comparison with QMS assay.

BACKGROUND: Teicoplanin is a glycopeptide antibiotic used for the treatment of infections caused by Gram-positive bacteria. There is a good correlation between trough levels and clinical outcome, therefore therapeutic drug monitoring is recommended. Here we present a liquid chromatography-mass spectrometry (LC-MS) method with online extraction based on turbulent flow chromatography for the quantification of the five main components of teicoplanin, A2-1, A2-2, A2-3, A2-4, and A2-5. METHODS: After online extraction, analytical chromatography was performed on a Hypersil Gold C8 column under acidic conditions. As mass spectrometer, a Q Exactive hybrid instrument was used. Samples were prepared by adding internal standard and subsequent centrifugation. Patient samples (n=125) that had previously been analyzed using a commercially available immunoassay (QMS teicoplanin) were re-analyzed by LC-MS. RESULTS: The imprecision was <6.9%, inaccuracy between 99.6% and 109%, for both, within- and between-day analysis. The method was shown to be free of matrix effects in the relevant time ranges and was compared to a commercially available immunoassay, QMS® teicoplanin from Thermo Fisher Scientific. The LC-MS assay produced comparable results to the QMS assay, the correlation coefficient was 0.856 (95% confidence interval 0.800-0.896). LC-MS yielded lower concentrations than the immunoassay as could be demonstrated by the bias of -1.16 mg/L (95% confidence interval -1.90-0.43 mg/L) in the Bland-Altman analysis. CONCLUSIONS: This specific, automated, LC-MS assay for teicoplanin is suitable for therapeutic drug monitoring.