Acute Coronary Syndrome Subphenotypes Based on Repeated Biomarker Measurements in Relation to Long-Term Mortality Risk.

BACKGROUND: We aimed to identify patients with subphenotypes of postacute coronary syndrome (ACS) using repeated measurements of high-sensitivity cardiac troponin T, N-terminal pro-B-type natriuretic peptide, high-sensitivity C-reactive protein, and growth differentiation factor 15 in the year after the index admission, and to investigate their association with long-term mortality risk. METHODS AND RESULTS: BIOMArCS (BIOMarker Study to Identify the Acute Risk of a Coronary Syndrome) was an observational study of patients with ACS, who underwent high-frequency blood sampling for 1 year. Biomarkers were measured in a median of 16 repeated samples per individual. Cluster analysis was performed to identify biomarker-based subphenotypes in 723 patients without a repeat ACS in the first year. Patients with a repeat ACS (N=36) were considered a separate cluster. Differences in all-cause death were evaluated using accelerated failure time models (median follow-up, 9.1 years; 141 deaths). Three biomarker-based clusters were identified: cluster 1 showed low and stable biomarker concentrations, cluster 2 had elevated concentrations that subsequently decreased, and cluster 3 showed persistently elevated concentrations. The temporal biomarker patterns of patients in cluster 3 were similar to those with a repeat ACS during the first year. Clusters 1 and 2 had a similar and favorable long-term mortality risk. Cluster 3 had the highest mortality risk. The adjusted survival time ratio was 0.64 (95% CI, 0.44-0.93; P=0.018) compared with cluster 1, and 0.71 (95% CI, 0.39-1.32; P=0.281) compared with patients with a repeat ACS. CONCLUSIONS: Patients with subphenotypes of post-ACS with different all-cause mortality risks during long-term follow-up can be identified on the basis of repeatedly measured cardiovascular biomarkers. Patients with persistently elevated biomarkers have the worst outcomes, regardless of whether they experienced a repeat ACS in the first year.

Ensuring quality in 17OHP mass spectrometry measurement: an international study assessing isomeric steroid interference.

OBJECTIVES: Interference from isomeric steroids is a potential cause of disparity between mass spectrometry-based 17-hydroxyprogesterone (17OHP) results. We aimed to assess the proficiency of mass spectrometry laboratories to report 17OHP in the presence of known isomeric steroids. METHODS: A series of five samples were prepared using a previously demonstrated commutable approach. These samples included a control (spiked to 15.0 nmol/L 17OHP) and four challenge samples further enriched with equimolar concentrations of 17OHP isomers (11α-hydroxyprogesterone, 11ß-hydroxyprogesterone, 16α-hydroxyprogesterone or 21-hydroxyprogesterone). These samples were distributed to 38 participating laboratories that reported serum 17OHP results using mass spectrometry in two external quality assurance programs. The result for each challenge sample was compared to the control sample submitted by each participant. RESULTS: Twenty-six laboratories (68 % of distribution) across three continents returned results. Twenty-five laboratories used liquid chromatography-tandem mass spectrometry (LC-MS/MS), and one used gas chromatography-tandem mass spectrometry to measure 17OHP. The all-method median of the control sample was 14.3 nmol/L, ranging from 12.4 to 17.6 nmol/L. One laboratory had results that approached the lower limit of tolerance (minus 17.7 % of the control sample), suggesting the isomeric steroid caused an irregular result. CONCLUSIONS: Most participating laboratories demonstrated their ability to reliably measure 17OHP in the presence of the four clinically relevant isomeric steroids. The performance of the 12 (32 %) laboratories that did not engage in this activity remains unclear. We recommend that all laboratories offering LC-MS/MS analysis of 17OHP in serum, plasma, or dried bloodspots determine that the isomeric steroids are appropriately separated.

Identifying lipid traces of atherogenic mechanisms in human carotid plaque.

BACKGROUND AND AIMS: Lipids play an important role in atherosclerotic plaque development and are interesting candidate predictive biomarkers. However, the link between circulating lipids, accumulating lipids in the vessel wall, and plaque destabilization processes in humans remains largely unknown. This study aims to provide new insights into the role of lipids in atherosclerosis using lipidomics and mass spectrometry imaging to investigate lipid signatures in advanced human carotid plaque and plasma samples. METHODS: We used lipidomics and desorption electrospray ionization mass spectrometry imaging (DESI-MSI) to investigate lipid signatures of advanced human carotid plaque and plasma obtained from patients who underwent carotid endarterectomy (n = 14 out of 17 whose plaque samples were analyzed by DESI-MSI). Multivariate data analysis and unsupervised clustering were applied to identify lipids that were the most discriminative species between different patterns in plaque and plasma. These patterns were interpreted by quantitative comparison with conventional histology. RESULTS: Lipidomics detected more than 300 lipid species in plasma and plaque, with markedly different relative abundances. DESI-MSI visualized the spatial distribution of 611 lipid-related m/z features in plaques, of which 330 m/z features could be assigned based on exact mass, comparison to the lipidomic data, and high mass resolution MSI. Matching spatial lipid patterns to histological areas of interest revealed several molecular species that were colocalized with pertinent disease processes in plaque including specific sphingomyelin and ceramide species with calcification, phospholipids and free fatty acids with inflammation, and triacylglycerols and phosphatidylinositols with fibrin-rich areas. CONCLUSIONS: By comparing lipid species in plaque and plasma, we identified those circulating species that were also prominently present in plaque. Quantitative comparison of lipid spectral patterns with histology revealed the presence of specific lipid species in destabilized plaque areas, corroborating previous in vitro and animal studies.

Over- and Undertreatment With Levothyroxine.

BACKGROUND: Levothyroxine is a very commonly prescribed drug, and treatment with it is often insufficient or excessive. Nonetheless, there have been only a few reports on the determinants of inadequate levothyroxine treatment. METHODS: Data from 2938 participants in the population-based Rhineland Study were analyzed. Putative determinants of inadequate levothyroxine treatment (overtreatment, thyrotropin level <0.56 mU/L; undertreatment, thyrotropin level >4.27 mU/L) were studied with logistic regression. The determinants of the levothyroxine dose were assessed with linear regression. RESULTS: Overall, 23% of the participants (n = 662) stated that they were taking levothyroxine. Among these participants, 18% were overtreated and 4% were undertreated. Individuals over 70 years of age and above were four times as likely to be overtreated (OR = 4.05, 95% CI [1.20; 13.72]). Each rise in the levothyroxine dose by 25 µg was associated with an increased risk of overtreatment (OR = 1.02, 95% CI [1.02; 1.03]) and of undertreatment (OR = 1.02, 95% CI [1.00; 1.03]). Well-controlled participants (normal thyrotropin levels 0.56-4.27 mU/L) received a lower levothyroxine dose (1.04 ± 0.5 µg/kg/d) than overtreated (1.40 ±0.5 µg/kg/d) or undertreated (1.37 ±0.5 µg/kg/d) participants. No association was found between sociodemographic factors or comorbidities and the levothyroxine dose. Iodine supplementation was associated with a lower daily dose (ß = -0.19, 95% CI [-0.28; -0.10]), while three years or more of levothyroxine exposure was associated with a higher daily dose (ß = 0.24, 95% CI [0.07; 0.41]). CONCLUSION: Levothyroxine intake was high in our sample, and suboptimal despite monitoring. Our findings underscore the need for careful dosing and for due consideration of deintensification of treatment where appropriate.

Circulating biomarkers associated with aortic diameter in male and female patients with thoracic aortic disease: a cross-sectional study.

OBJECTIVE: As thoracic aortic disease (TAD) is generally asymptomatic, biomarkers are needed to provide insight into early progression. We aimed to examine the association between circulating blood biomarkers and the maximal thoracic aortic diameter (TADmax). METHODS: In this cross-sectional study, consecutive adult patients with a thoracic aortic diameter ≥40 mm and/or genetically proven hereditary TAD (HTAD) visiting our specialised outpatient clinic between 2017 and 2020 were prospectively included. Venous blood sampling and CT angiography and/or transthoracic echocardiography of the aorta were performed. Linear regression analyses were performed and estimates were presented as mean difference in TADmax in mm per doubling of standardised biomarker level. RESULTS: In total, 158 patients were included (median age 61 (50.3-68.8) years, 37.3% female). HTAD diagnosis was confirmed in 36 of 158 (22.7%) patients. TADmax was 43.9±5.2 mm in men vs 41.9±5.1 in women (p=0.030). In unadjusted analysis, significant associations with TADmax were found for interleukin-6 (1.15 (95% CI 0.33 to 1.96), p=0.006), growth differentiation factor-15 (1.01 (95% CI 0.18 to 1.84), p=0.018), microfibrillar-associated protein 4 (MFAP4) (-0.88 (95% CI -1.71 to 0.05), p=0.039) and triiodothyronine (T3) (-2.00 (95%CI -3.01 to 0.99), p<0.001). The association of MFAP4 with TADmax was stronger in women (p for interaction=0.020) and for homocysteine, an inverse association with TADmax was observed when compared with men (p for interaction=0.008). When adjusted for age, sex, hyperlipidaemia and HTAD, total cholesterol (1.10 (95% CI 0.27 to 1.93), p=0.010) and T3 (-1.20 (95% CI -2.14 to 0.25), p=0.014) were significantly associated with TADmax. CONCLUSIONS: Circulating biomarkers indicative of inflammation, lipid metabolism and thyroid function might be associated with TAD severity. Possible distinct biomarker patterns for men and women warrant further investigation.

Lipoprotein(a) is associated with a larger systemic burden of arterial calcification.

AIMS: Lipoprotein(a) [Lp(a)] is a genetically determined risk factor for cardiovascular disease. However, population-based evidence on the link between Lp(a) and subclinical arteriosclerosis is lacking. We assessed associations of Lp(a) concentrations with arteriosclerosis in multiple arteries. METHODS AND RESULTS: From the population-based Rotterdam study, 2354 participants (mean age: 69.5 years, 52.3% women) underwent non-contrast computed tomography to assess arterial calcification as a hallmark of arteriosclerosis. We quantified the volume of coronary artery calcification (CAC), aortic arch calcification (AAC), extracranial (ECAC), and intracranial carotid artery calcification (ICAC). All participants underwent blood sampling, from which plasma Lp(a) concentrations were derived. The association of plasma Lp(a) levels was assessed with calcification volumes and with severe calcification (upper quartile of calcification volume) using sex-stratified multivariable linear and logistic regression models. Higher Lp(a) levels were associated with larger ln-transformed volumes of CAC [fully adjusted beta 95% confidence interval (CI) per 1 standard deviation (SD) in women: 0.09, 95% CI 0.04-0.14, men: 0.09, 95% CI 0.03-0.14], AAC (women: 0.06, 95% CI 0.01-0.11, men: 0.09, 95% CI 0.03-0.14), ECAC (women: 0.07, 95% CI 0.02-0.13, men: 0.08, 95% CI 0.03-0.14), and ICAC (women: 0.09, 95% CI 0.03-0.14, men: 0.05, 95% CI -0.02 to 0.11]. In the highest Lp(a) percentile, severe ICAC was most prevalent in women [fully adjusted odds ratio (OR) 2.41, 95% CI 1.25-4.63] and severe AAC in men (fully adjusted OR 3.29, 95% CI 1.67-6.49). CONCLUSION: Higher Lp(a) was consistently associated with a larger calcification burden in all major arteries. The findings of this study indicate that Lp(a) is a systemic risk factor for arteriosclerosis and thus potentially an effective target for treatment. Lp(a)-reducing therapies may reduce the burden from arteriosclerotic events throughout the arterial system. TRANSLATIONAL PERSPECTIVE: In 2354 participants from the Rotterdam study, we assessed the link between Lp(a) concentrations and arterial calcifications, as proxy for arteriosclerosis, in major arteries. We found that higher Lp(a) levels were consistently associated with larger volumes of calcification in the coronary arteries, aortic arch, extracranial carotid arteries, and intracranial carotid arteries. The findings of our study indicate that Lp(a) is a systemic risk factor for arteriosclerosis, suggesting that the systemic burden of arteriosclerosis throughout the arterial system could be reduced by targeting Lp(a).

Serially measured high-sensitivity cardiac troponin T, N-terminal-pro-B-type natriuretic peptide, high-sensitivity C-reactive protein, and growth differentiation factor 15 for risk assessment after acute coronary syndrome: the BIOMArCS cohort.

AIMS: Evidence regarding the role of serial measurements of biomarkers for risk assessment in post-acute coronary syndrome (ACS) patients is limited. The aim was to explore the prognostic value of four, serially measured biomarkers in a large, real-world cohort of post-ACS patients. METHODS AND RESULTS: BIOMArCS is a prospective, multi-centre, observational study in 844 post-ACS patients in whom 12 218 blood samples (median 17 per patient) were obtained during 1-year follow-up. The longitudinal patterns of high-sensitivity cardiac troponin T (hs-cTnT), N-terminal-pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity C-reactive protein (hs-CRP), and growth differentiation factor 15 (GDF-15) were analysed in relation to the primary endpoint (PE) of cardiovascular mortality and recurrent ACS using multivariable joint models. Median age was 63 years, 78% were men and the PE was reached by 45 patients. The average biomarker levels were systematically higher in PE compared with PE-free patients. After adjustment for 6-month post-discharge Global Registry of Acute Coronary Events score, 1 standard deviation increase in log[hs-cTnT] was associated with a 61% increased risk of the PE [hazard ratio (HR) 1.61, 95% confidence interval (CI) 1.02-2.44, P = 0.045], while for log[GDF-15] this was 81% (HR 1.81, 95% CI 1.28-2.70, P = 0.001). These associations remained significant after multivariable adjustment, while NT-proBNP and hs-CRP were not. Furthermore, GDF-15 level showed an increasing trend prior to the PE (Structured Graphical Abstract). CONCLUSION: Longitudinally measured hs-cTnT and GDF-15 concentrations provide prognostic value in the risk assessment of clinically stabilized patients post-ACS. CLINICAL TRIAL REGISTRATION: The Netherlands Trial Register. Currently available at URL https://trialsearch.who.int/; Unique Identifiers: NTR1698 and NTR1106.

Characterization of Laboratory Flow and Performance for Process Improvements via Application of Process Mining.

BACKGROUND: The rising level of laboratory automation provides an increasing number of logged events that can be used for the characterization of laboratory performance and process improvements. This abundance of data is often underutilized for improving laboratory efficiency. OBJECTIVES: The first aim of this descriptive study is to provide a structured approach for transforming raw laboratory data to data that is suitable for process mining. The second aim is to describe a process mining approach for mapping and characterizing the sample flow in a clinical chemistry laboratory to identify areas for improvement in the testing process. METHODS: Data were extracted from instrument log files and the middleware between laboratory instruments and information technology infrastructure. Process mining was used for automated process discovery and analysis. Laboratory performance was quantified in terms of relevant key performance indicators (KPIs): turnaround time, timeliness, workload, work-in-process, and machine downtime. RESULTS: The method was applied to two Dutch university hospital clinical chemistry laboratories. We identified areas where alternative routes might increase laboratory efficiency and observed the negative effects of machine downtime on laboratory performance. This encourages the laboratory to review sample routes in its analyzer lines, the routes of high priority samples during instrument downtime, as well as the preventive maintenance policy. CONCLUSION: This article provides the first application of process mining to event data from a medical diagnostic laboratory for automated process model discovery. Our study shows that process mining, with the use of relevant KPIs, provides valuable insights for laboratories that motivates the disclosure and increased utilization of laboratory event data, which in turn drive the analytical staff to intervene in the process to achieve the set performance goals. Our approach is vendor independent and widely applicable for all medical diagnostic laboratories.

Asymmetrical Transport of Thyroxine Across Human Term Placenta.

Background: Fetal development is crucially dependent on thyroid hormone (TH). Maternal-to-fetal transfer of TH is a prerequisite for fetal TH availability, particularly in the first half of pregnancy. The mechanisms of transplacental transport of TH, however, are yet poorly understood. We, therefore, investigated the TH transport processes across human placentas using an ex vivo perfusion system. Methods: Intact cotyledons from term placentas of uncomplicated pregnancies were cannulated within 30 minutes after delivery and the maternal and fetal circulations were re-established. One hundred nanomolar thyroxine (T4) was added to either the maternal or fetal circulation and perfusions run up to three hours during which samples were taken from both circulations at different time points. Variables included addition of iopanoic acid (IOP) to block activity of the deiodinase type 3 (D3) and bovine serum albumin (BSA) to trap released T4. T4 and 3,3',5'-triiodothyronine concentrations in the perfusates were measured by radioimmunoassays. Results: Maternal-to-fetal transfer was slow, with T4 barely detectable in the fetal circulation unless D3 was blocked by IOP. Fetal T4 was detected after three hours perfusion (10.6 ± 0.6 nM) when BSA (34 g/L) was added in the fetal circulation to trap the released T4. In contrast, fetal-to-maternal transfer of T4 was rapid and maternal T4 increased to 43.6 ± 5.5 nM. Conclusions: Maternal-to-fetal T4 transport is limited, whereas fetal-to-maternal transport is rapid indicating that T4 transport across human term placenta is an asymmetrical process. With the high D3 activity, our observations are compatible with a protective role of the placental barrier. Future studies should reveal how the placenta exerts its gatekeeper function in ensuring optimal TH passage to the fetus.

Simultaneous quantification of tryptophan metabolites by liquid chromatography tandem mass spectrometry during early human pregnancy.

OBJECTIVES: In this study we describe the development and validation of a liquid chromatography mass spectrometry method (LC-MS/MS) to quantify five tryptophan (TRP) metabolites within the kynurenine- and serotonin pathway and apply the method to serum samples of women in the first trimester of pregnancy. A secondary aim was to investigate the correlation between body mass index (BMI) and the five analytes. METHODS: A LC-MS/MS was developed for the analysis of TRP, kynurenine (KYN), 5-hydroxytryptophan (5-HTP), hydroxytryptamine (5-HT), and 5-hydroxyindole acetic acid (5-HIAA). Serum samples (n=374) were analyzed of pregnant women (median gestational age: 8 ± 2 weeks) participating in a subcohort of the Rotterdam Periconceptional Cohort (Predict study). RESULTS: The LC-MS/MS method provided satisfactory separation of the five analytes (7 min run). For all analytes R2 was >0.995. Within- and between-run accuracies were 72-97% and 79-104%, and the precisions were all <15% except for the between-run precisions of the low QC-samples of 5-HTP and 5-HT (both 16%). Analyte concentrations were determined in serum samples of pregnant women (median (IQR)); TRP (µmol/L): 57.5 (13.4), KYN (µmol/L): 1.4 (0.4), 5-HTP (nmol/L): 4.1 (1.2), 5-HT (nmol/L): 615 (323.1), and 5-HIAA (nmol/L): 39.9 (17.0). BMI was negatively correlated with TRP, 5-HTP, and 5-HIAA (TRP: r=-0.18, p<0.001; 5-HTP: r=-0.13, p=0.02; natural log of 5-HIAA: r=-0.11, p=0.04), and positively with KYN (r=0.11, p=0.04). CONCLUSIONS: The LC-MS/MS method is able to accurately quantify kynurenine- and serotonin pathway metabolites in pregnant women, providing an opportunity to investigate the role of the TRP metabolism in the (patho)physiology of pregnancy.

The Role of the Kynurenine Pathway in the (Patho) physiology of Maternal Pregnancy and Fetal Outcomes: A Systematic Review.

Introduction: Tryptophan is the precursor of kynurenine pathway (KP) metabolites which regulate immune tolerance, energy metabolism, and vascular tone. Since these processes are important during pregnancy, changes in KP metabolite concentrations may play a role in the pathophysiology of pregnancy complications. We hypothesize that KP metabolites can serve as novel biomarkers and preventive therapeutic targets. This review aimed to provide more insight into associations between KP metabolite concentrations in maternal and fetal blood, and in the placenta, and adverse maternal pregnancy and fetal outcomes. Methods: A systematic search was performed on 18 February 2022 comprising all KP metabolites, and keywords related to maternal pregnancy and fetal outcomes. English-written human studies measuring KP metabolite(s) in maternal or fetal blood or in the placenta in relation to pregnancy complications, were included. Methodological quality was assessed using the ErasmusAGE quality score (QS) (range: 0-10). A meta-analysis of the mean maternal tryptophan and kynurenine concentrations in uncomplicated pregnancies was conducted. Results: Of the 6262 unique records, 37 were included (median QS = 5). Tryptophan was investigated in most studies, followed by kynurenine, predominantly in maternal blood (n = 28/37), and in the second and third trimester of pregnancy (n = 29/37). Compared to uncomplicated pregnancies, decreased tryptophan in maternal blood was associated with an increased prevalence of depression, gestational diabetes mellitus, fetal growth restriction, spontaneous abortion, and preterm birth. Elevated tryptophan was only observed in women with pregnancy-induced hypertension compared to normotensive pregnant women. In women with preeclampsia, only kynurenic acid was altered; elevated in the first trimester of pregnancy, and positively associated with proteinuria in the third trimester of pregnancy. Conclusions: KP metabolite concentrations were altered in a variety of maternal pregnancy and fetal complications. This review implies that physiological pregnancy requires a tight balance of KP metabolites, and that disturbances in either direction are associated with adverse maternal pregnancy and fetal outcomes.

Development and validation of an early warning model for hospitalized COVID-19 patients: a multi-center retrospective cohort study.

BACKGROUND: Timely identification of deteriorating COVID-19 patients is needed to guide changes in clinical management and admission to intensive care units (ICUs). There is significant concern that widely used Early warning scores (EWSs) underestimate illness severity in COVID-19 patients and therefore, we developed an early warning model specifically for COVID-19 patients. METHODS: We retrospectively collected electronic medical record data to extract predictors and used these to fit a random forest model. To simulate the situation in which the model would have been developed after the first and implemented during the second COVID-19 'wave' in the Netherlands, we performed a temporal validation by splitting all included patients into groups admitted before and after August 1, 2020. Furthermore, we propose a method for dynamic model updating to retain model performance over time. We evaluated model discrimination and calibration, performed a decision curve analysis, and quantified the importance of predictors using SHapley Additive exPlanations values. RESULTS: We included 3514 COVID-19 patient admissions from six Dutch hospitals between February 2020 and May 2021, and included a total of 18 predictors for model fitting. The model showed a higher discriminative performance in terms of partial area under the receiver operating characteristic curve (0.82 [0.80-0.84]) compared to the National early warning score (0.72 [0.69-0.74]) and the Modified early warning score (0.67 [0.65-0.69]), a greater net benefit over a range of clinically relevant model thresholds, and relatively good calibration (intercept = 0.03 [- 0.09 to 0.14], slope = 0.79 [0.73-0.86]). CONCLUSIONS: This study shows the potential benefit of moving from early warning models for the general inpatient population to models for specific patient groups. Further (independent) validation of the model is needed.

Sex steroids and sex steroid-binding globulin levels amongst middle-aged and elderly men and women from general population.

BACKGROUND AND AIMS: Availability of age- and sex-specific reference values for sex steroids and sex steroid-binding globulin (SHBG) levels allows for appropriate interpretation of research findings and their clinical applications. We report the sex-specific distribution and reference levels of sex steroids, including total estradiol, total testosterone and (calculated) free androgen index (cFAI), SHBG and other androgens dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulphate (DHEAS) and androstenedione across age. METHODS: Using data from 3291 participants from the prospective population-based Rotterdam Study (2006-2008), we visualised the distribution of sex steroids and SHBG levels by calculating and depicting the 5th, 25th, 50th, 75th and 95th percentiles per year and per age-year across 5-year age bands to provide reference value ranges in men and women. Total estradiol and SHBG were measured using automated immunoassay and androgens using liquid chromatography-mass spectrometry (LC-MS/MS). RESULT: Mean age was 56.8 (range 45.6-79.9) years in men and 56.9 (range 45.7-79.9) years in women. Amongst men, total estradiol and SHBG showed an increasing trend from 45 years onwards. In women, total estradiol and SHBG showed a decreasing trend from 45 years until the age of 60. From 60 years onwards, SHBG showed an increasing trend. For total testosterone, a clear declining trend was observed amongst men but not women. Other androgens showed a similar decreasing trend in both sexes from 45 years onwards. DISCUSSION AND CONCLUSION: Our study underlines sex-specific trends in sex steroids and SHBG levels with ageing. This warrants taking into account sex- and age-specific reference values for sex steroids and SHBG when investigating their impact on health outcomes to prevent controversial results and allow for their appropriate clinical application.

Kynurenine metabolites predict survival in pulmonary arterial hypertension: A role for IL-6/IL-6Rα.

Activation of the kynurenine pathway (KP) has been reported in patients with pulmonary arterial hypertension (PAH) undergoing PAH therapy. We aimed to determine KP-metabolism in treatment-naïve PAH patients, investigate its prognostic values, evaluate the effect of PAH therapy on KP-metabolites and identify cytokines responsible for altered KP-metabolism. KP-metabolite levels were determined in plasma from PAH patients (median follow-up 42 months) and in rats with monocrotaline- and Sugen/hypoxia-induced PH. Blood sampling of PAH patients was performed at the time of diagnosis, six months and one year after PAH therapy. KP activation with lower tryptophan, higher kynurenine (Kyn), 3-hydroxykynurenine (3-HK), quinolinic acid (QA), kynurenic acid (KA), and anthranilic acid was observed in treatment-naïve PAH patients compared with controls. A similar KP-metabolite profile was observed in monocrotaline, but not Sugen/hypoxia-induced PAH. Human lung primary cells (microvascular endothelial cells, pulmonary artery smooth muscle cells, and fibroblasts) were exposed to different cytokines in vitro. Following exposure to interleukin-6 (IL-6)/IL-6 receptor α (IL-6Rα) complex, all cell types exhibit a similar KP-metabolite profile as observed in PAH patients. PAH therapy partially normalized this profile in survivors after one year. Increased KP-metabolites correlated with higher pulmonary vascular resistance, shorter six-minute walking distance, and worse functional class. High levels of Kyn, 3-HK, QA, and KA measured at the latest time-point were associated with worse long-term survival. KP-metabolism was activated in treatment-naïve PAH patients, likely mediated through IL-6/IL-6Rα signaling. KP-metabolites predict response to PAH therapy and survival of PAH patients.

Lipoprotein(a) is associated with the onset but not the progression of aortic valve calcification.

AIM: Lipoprotein(a) [Lp(a)] is a potential causal factor in the pathogenesis of aortic valve disease. However, the relationship of Lp(a) with new onset and progression of aortic valve calcium (AVC) has not been studied. The purpose of the study was to assess whether high serum levels of Lp(a) are associated with AVC incidence and progression. METHODS AND RESULTS: A total of 922 individuals from the population-based Rotterdam Study (mean age 66.0±4.2 years, 47.7% men), whose Lp(a) measurements were available, underwent non-enhanced cardiac computed tomography imaging at baseline and after a median follow-up of 14.0 [interquartile range (IQR) 13.9-14.2] years. New-onset AVC was defined as an AVC score >0 on the follow-up scan in the absence of AVC on the first scan. Progression was defined as the absolute difference in AVC score between the baseline and follow-up scan. Logistic and linear regression analyses were performed to evaluate the relationship of Lp(a) with baseline, new onset, and progression of AVC. All analyses were corrected for age, sex, body mass index, smoking, hypertension, dyslipidaemia, and creatinine. AVC progression was analysed conditional on baseline AVC score expressed as restricted cubic splines. Of the 702 individuals without AVC at baseline, 415 (59.1%) developed new-onset AVC on the follow-up scan. In those with baseline AVC, median annual progression was 13.5 (IQR = 5.2-37.8) Agatston units (AU). Lipoprotein(a) concentration was independently associated with baseline AVC [odds ratio (OR) 1.43 for each 50 mg/dL higher Lp(a); 95% confidence interval (CI) 1.15-1.79] and new-onset AVC (OR 1.30 for each 50 mg/dL higher Lp(a); 95% CI 1.02-1.65), but not with AVC progression (ß: -71 AU for each 50 mg/dL higher Lp(a); 95% CI -117; 35). Only baseline AVC score was significantly associated with AVC progression (P < 0.001). CONCLUSION: In the population-based Rotterdam Study, Lp(a) is robustly associated with baseline and new-onset AVC but not with AVC progression, suggesting that Lp(a)-lowering interventions may be most effective in pre-calcific stages of aortic valve disease.

The effect of cold exposure on circulating transcript levels of immune genes in Dutch South Asian and Dutch Europid men.

OBJECTIVES: Although cold exposure is commonly believed to be causally related to acute viral respiratory infections, its effect on the immune system is largely unexplored. In this study, we determined transcript levels of a large panel of immune genes in blood before and after cold exposure. We included both Dutch Europid and Dutch South Asian men to address whether the immune system is differently regulated in the metabolically vulnerable South Asian population. METHODS: Fasted blood samples were obtained from nonobese Dutch Europid (n = 11; mean age 26 ± 3 y) and Dutch South Asian (n = 12; mean age 28 ± 3 y) men before and directly after short-term (∼2.5 h) mild cold exposure. Transcript levels of 144 immune genes were measured using a dual-color reverse transcriptase multiplex ligation-dependent probe amplification (dcRT-MLPA) assay. RESULTS: Cold exposure acutely upregulated mRNA levels of GNLY (+35%, P < 0.001) and PRF1 (+45%, P < 0.001), which encode cytotoxic proteins, and CCL4 (+8%, P < 0.01) and CCL5 (+5%, P < 0.05), both pro-inflammatory chemokines. At thermoneutrality, mRNA levels of four markers of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR)-family, involved in inflammasomes, were lower in Dutch South Asians compared to Dutch Europids, namely NLRP2 (-57%, P < 0.05), NLRP7 (-17%, P < 0.05), NLRP10 (-21%, P < 0.05), and NLRC4 (-23%, P < 0.05). CONCLUSIONS: Mild cold exposure acutely increases mRNA levels of genes involved in cytotoxicity of immune cells in blood. In addition, Dutch South Asians display lower circulating mRNA levels of inflammasome genes compared to Dutch Europids.

Obesity and Hyperphagia With Increased Defective ACTH: A Novel POMC Variant.

OBJECTIVE: Patients with pro-opiomelanocortin (POMC) defects generally present with early-onset obesity, hyperphagia, hypopigmentation and adrenocorticotropin (ACTH) deficiency. Rodent models suggest that adequate cleavage of ACTH to α-melanocortin-stimulating hormone (α-MSH) and desacetyl-α-melanocortin-stimulating hormone (d-α-MSH) by prohormone convertase 2 at the KKRR region is required for regulating food intake and energy balance. METHODS: We present 2 sisters with a novel POMC gene variant, leading to an ACTH defect at the prohormone convertase 2 cleavage site, and performed functional studies of this variant. RESULTS: The patients had obesity, hyperphagia and hypocortisolism, with markerly raised levels of ACTH but unaffected pigmentation. Their ACTH has reduced potency to stimulate the melanocortin (MC) 2 receptor, explaining their hypocortisolism. CONCLUSION: The hyperphagia and obesity support evidence that adequate cleavage of ACTH to α-MSH and d-α-MSH is also required in humans for feeding control.

Binding Characteristics of Thyroid Hormone Distributor Proteins to Thyroid Hormone Metabolites.

Background: In contrast to the thyroid hormones (THs) 3,3',5-triiodothyronine (T3) and 3,3',5,5'-tetraiodothyronine (thyroxine or T4), the binding characteristics of the thyroid hormone distributor proteins (THDP), thyroxine-binding globulin (TBG), albumin, and transthyretin in relation to TH metabolites are mostly lacking. In this study, we determined the distribution and binding affinity of TH metabolites to THDP, which is important for adequate interpretation of TH metabolite concentrations. Methods: Distribution of 125I-3,3'-diiodothyronine (3,3'-T2), -T3, -3,3',5'-triiodothyronine (rT3), -3,3',5-triiodothyroacetic acid (TA3), and -3,3',5,5'-tetraiodothyroacetic acid (TA4) to TBG, transthyretin, and albumin was determined by agar gel electrophoresis. The rank order of affinity (IC50) of TBG and transthyretin to thyronine (T0), 3-monoiodothyronine (3-T1), 3,5-diiodothyronine (3,5-T2), 3,3'-T2, T3, rT3, T4, TA3, and TA4 was determined with a radioligand, competitive binding assay. In healthy subjects, associations of serum TBG, transthyretin, and albumin with TH and its metabolites were analyzed using multiple linear regression models, adjusted for sex and age. Results: While T3 and T4 are predominantly bound to TBG, we demonstrated that the predominant THDP of 3,3'-T2 and rT3 is albumin, of TA3 is transthyretin and albumin, and of TA4 is transthyretin. With the radioligand binding assay, we showed that the rank order of affinity was T4>TA4 = rT3>T3>TA3 = 3,3'-T2 > 3-T1 = 3,5-T2>T0 for TBG (IC50-range: 0.36 nM to >100 µM) and TA4>T4 = TA3>rT3>T3 > 3,3'-T2 > 3-T1 > 3,5-T2>T0 for transthyretin (IC50-range: 0.94 nM to >100 µM). TBG, transthyretin, and albumin were not associated with T0, 3-T1, 3,3'-T2, rT3, and TA4. Conclusions: Differences in serum TBG, transthyretin, and albumin concentrations within the reference interval do not influence serum concentrations of T0, 3-T1, 3,3'-T2, rT3, and TA4. Distribution of TH metabolites between THDP differs from T4 and T3, which predominantly bind to TBG. The results from our study have potential clinical importance for adequate interpretation of TH metabolism in (patho)physiology.

Maternal lipid profile in pregnancy and embryonic size: a population-based prospective cohort study.

BACKGROUND: Lipids are crucial for fetal growth and development. Maternal lipid concentrations are associated with fetal growth in the second and third trimester of pregnancy and with birth outcomes. However, it is unknown if this association starts early in pregnancy or arises later during fetal development. The aim of this study was to investigate the association between the maternal lipid profile in early pregnancy and embryonic size. METHODS: We included 1474 women from the Generation R Study, a population based prospective birth cohort. Both embryonic size and the maternal lipid profile were measured between 10 weeks + 1 day and 13 weeks + 6 days gestational age. The maternal lipid profile was defined as total cholesterol, triglycerides (TG), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), remnant cholesterol, non-high-density (non-HDL-c) lipoprotein cholesterol concentrations and the triglycerides/high-density lipoprotein (TG/HDL-c) ratio. Additionally, maternal glucose concentrations were assessed. Embryonic size was assessed using crown-rump length (CRL) measurements. Associations were studied with linear regression models, adjusted for confounding factors: maternal age, pre-pregnancy body mass index (BMI), parity, educational level, ethnicity, smoking and folic acid supplement use. RESULTS: Triglycerides and remnant cholesterol concentrations are positively associated with embryonic size (fully adjusted models, 0.17 SDS CRL: 95% CI 0.03; 0.30, and 0.17 SDS: 95% CI 0.04; 0.31 per 1 MoM increase, respectively). These associations were not present in women with normal weight (triglycerides and remnant cholesterol: fully adjusted model, 0.44 SDS: 95% CI 0.15; 0.72). Associations between maternal lipid concentrations and embryonic size were not attenuated after adjustment for glucose concentrations. Total cholesterol, HDL-c, LDL-c, non-HDL-c concentrations and the TG/HDL-c ratio were not associated with embryonic size. CONCLUSIONS: Higher triglycerides and remnant cholesterol concentrations in early pregnancy are associated with increased embryonic size, most notably in overweight women. TRIAL REGISTRATION: The study protocol has been approved by the Medical Ethics Committee of the Erasmus University Medical Centre (Erasmus MC), Rotterdam (MEC-2007-413). Written informed consent was obtained from all participants.