Single Time Point Measurements Research Articles

Probing transient memory of cellular states using single-cell lineages.

The inherent stochasticity in the gene product levels can drive single cells within an isoclonal population to different phenotypic states. The dynamic nature of this intercellular variation, where individual cells can transition between different states over time, makes it a particularly hard phenomenon to characterize. We reviewed recent progress in leveraging the classical Luria-Delbrück experiment to infer the transient heritability of the cellular states. Similar to the original experiment, individual cells were first grown into cell colonies, and then, the fraction of cells residing in different states was assayed for each colony. We discuss modeling approaches for capturing dynamic state transitions in a growing cell population and highlight formulas that identify the kinetics of state switching from the extent of colony-to-colony fluctuations. The utility of this method in identifying multi-generational memory of the both expression and phenotypic states is illustrated across diverse biological systems from cancer drug resistance, reactivation of human viruses, and cellular immune responses. In summary, this fluctuation-based methodology provides a powerful approach for elucidating cell-state transitions from a single time point measurement, which is particularly relevant in situations where measurements lead to cell death (as in single-cell RNA-seq or drug treatment) or cause an irreversible change in cell physiology.

Fetal Hemoglobin Induced Improvement in Relative Age of Sickle Red Blood Cells Determined through Glycated Hemoglobin Assessment By Flow Cytometry

Introduction: Sickle cell disease (SCD) is characterized by acute vaso-occlusive events and chronic hemolytic anemia, originating from the polymerization of the abnormal hemoglobin S (HbS) under low oxygen tension. Hemolysis is defined as an imbalance between the rate of red blood cell (RBC) production and destruction. It results in an overall reduced lifespan of RBCs, as they are prematurely removed from the circulation. While the normal RBC lifespan is approximatively 120 days, those of SCD is only a sixth of it (Hebbel, 2011). Fetal Hb (HbF) is the main clinical modulator of SCD severity by inhibiting HbS polymerization. Its protective effect relies on its quantity and distribution among the RBC population. However, HbF is often heterogeneously distributed in RBC from SCD patients. Among the numerous improvements triggered by HbF, a significant increase in RBC lifespan has been measured in high-HbF containing cells, as compared to low-HbF containing cells (Franco et al., 2006). As they age, normal RBCs exhibit physiological changes, such as dehydration, a decrease of the intracellular enzymes activities (pyruvate kinase and hexokinase) and an increase in Hb concentration. Glycated Hb (the most abundant being HbA1c form) also increases, as RBC age. The glycation of Hb is a non-enzymatical reaction that is affected by the plasmatic concentration of glucose and the time RBCs last in the circulation. In non-diabetic subjects, the Hb glycation only depends on the RBC lifespan. To date, current methods to assess RBC lifespan are invasive and time consuming, requiring infusion of autologous labeled RBCs and long follow-up. Objectives: This present work aims at 1/ evaluating the RBC relative age of SCD patients using glycated Hb measured by flow cytometry and 2/ estimating the HbF-induced increase in RBC lifespan of SCD patients. Methods: Glycated Hb was measured and compared between five healthy donors (AA), seven non-diabetic and non-transfused homozygous SCD patients (SS) and five non-diabetic, transfused SS patients. Total glycated Hb was measured by reference biochemical methods, cation-exchange high-pressure liquid chromatography or rapid glycohaemoglobin immunoassay (DCA test) used for AA-RBC and SS-RBC, respectively. The single cell glycation was assessed by flow cytometry using mouse anti-human HbA1c antibody. HbA, HbS and HbF were assessed by flow cytometry using anti βA-globin, anti βS-globin and anti g-globin antibodies, respectively. Results: The glycated Hb was significantly lower in SS patients than in healthy donors (glycated HbS =3.7%, glycated HbA =5.3%, p=0.0025 by DCA and HPLC respectively, and by flow cytometry p=0.0061). In transfused SS patients, results showed that glycated Hb was lower in autologous SS-RBCs than in AA-RBCs by a factor of four (P= 0.008), thus confirming the characterized reduced lifespan of SS RBCs. Glycated Hb levels were measured in RBC sub-populations based on their HbF level (high HbF or low HbF subfractions) in non-transfused SS patients. Glycated Hb level was lower in low HbF RBCs, as compared to high HbF RBCs (P=0.0023). This difference was not detected in healthy donors, thereby indicating that HbF has an effect on relative age only in SCD patients. Conclusion: Single cell glycated Hb assessed by flow cytometry allows to simultaneously estimate the relative age of different RBC sub-populations. This new tool is noninvasive and requires only one single time point measurement. It should also be considered to evaluate the efficacy of treatments that aim at improving hemolysis. Figure. Glycated Hb levels assessed by HPLC and DCA biochemical methods, and flow cytometry in different participant groups and RBC subpopulations. Results were expressed as median, percentage or mean fluorescence intensity (MFI) when appropriate. Glycated Hb level was compared between two groups using a nonparametric Mann-Whitney t-test. (A) Total glycated Hb measured by HPLC in AA healthy donors (n=5) and by DCA test in SS patients (n=7). (B) Single cell glycated Hb measured by flow cytometry in SS RBCs (n=7), compared to AA healthy donors (n=4). (C) Single cell glycated Hb measured in low HbF RBCs (n=7) and high HbF RBCs (purple, n=7) subpopulations in SS patients and AA healthy donors (n=4). Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Gamma counting protocols for the accurate quantification of 225Ac and 213Bi without the need for a secular equilibrium between parent and gamma-emitting daughter

BackgroundQuantification of actinium-225 through gamma counter measurements, when there is no secular equilibrium between actinium-225 and its gamma emitting daughters bismuth-213 and/or francium-221, can provide valuable information regarding the possible relocation of recoiled daughters such that related radiotoxicity effects can be evaluated. This study proposes a multiple time-point protocol using the bismuth-213 photopeak with measurements before secular equilibrium between actinium-225 and bismuth-213, and a single time-point protocol using both the francium-221 and bismuth-213 photopeak while assuming secular equilibrium between actinium-225 and francium-221 but not between bismuth-213 and actinium-225.ResultsGood agreement (i.e. 3% accuracy) was obtained when relying on a multiple time-points measurement of bismuth-213 to quantify both actinium-225 and excess of bismuth-213. Following scatter correction, actinium-225 can be accurately quantified using the francium-221 in a single time-point measurement within 3% of accuracy. The analysis performed on the stability data of [225Ac]Ac-DEPA and [225Ac]Ac-DOTA complexes, before secular equilibrium between bismuth-213 and actinium-225 was formed, revealed considerable amounts of unbound bismuth-213 (i.e. more than 90%) after 24 h of the radiolabeling most likely due to the recoiled daughter effect.ConclusionBoth protocols were able to accurately estimate 225Ac-activities provided the francium-221 energy window was corrected for the down scatter of the higher-energy gamma-emissions by bismuth-213. This could prove beneficial to study the recoiled daughter effect and redistribution of free bismuth-213 by monitoring the accumulation or clearance of bismuth-213 in different tissues during biodistribution studies or in patient samples during clinical studies. On the other hand, the single gamma counter measurement protocol, although required a 30 min waiting time, is more time and cost efficient and therefore more appropriate for standardized quality control procedures of 225Ac-labeled radiopharmaceuticals.

Results from a nationwide atrial fibrillation screening effort in Belgium

Abstract Introduction Atrial Fibrillation (AF) is associated with an increased risk of stroke that can be mitigated with anticoagulation therapy. Opportunistic screening for AF for primary stroke prevention is recommended in subjects above 65. However, the paroxysmal and asymptomatic nature of AF hampers early detection with a single time point screening. Multiple time point measurements are superior to single time point measurements for the detection of AF. New technologies such as photoplethysmography (PPG) enable large scale AF screening with repetitive measurements at low-cost using only a smartphone. Purpose To explore an entirely online AF screening program in subjects with an elevated stroke risk. Methods The Belgian Heart Rhythm Association launched a digital marketing campaign, to promote AF screening during “The Belgian Week of the Heart Rhythm”. Candidates were referred to an online questionnaire to calculate their CHADS-VASC score. Subjects older than 18 with a CHADS-VASC score of 2 or more were allowed to enter the screening program. AF screening was performed with a PPG-based smartphone application. A 60-second PPG trace is captured by placing a fingertip on the smartphone's camera. The smartphone application analyses the PPG trace with an artificial intelligence software. Subjects were instructed to perform measurement twice daily and while experiencing symptoms over the course of 7 days. Measurements were classified as AF or non-AF by the algorithm and were reviewed by medical technicians. Results Of the 12.602 candidates who completed the questionnaire, 6.020 subjects met the inclusion criteria and were offered screening. However, only 2.111 (35%) participated in the screening program. The mean age of participants was 63±11 years, 37.3% was male, median CHADS-VASC was 2 (2–3). 257 participants (12.2%) were previously known with AF. In total 25.362 PPG recordings of 60 seconds were performed of which 258 demonstrated AF. AF was detected in 56 participants (2.7%). This was a new finding in 36 participants (1.7%) meaning that 64.3% of participants demonstrating AF were not previously known with AF. The number needed to screen was 58.6 to detect AF in a population without a history of AF and the number needed to invite was 167.2. Only 20 participants (7.8%) with a history of AF demonstrated AF during the screening program. Conclusions AF screening in subjects with an elevated stroke risk is feasible with an entirely online screening program without the need for medical hardware or medical personnel with an acceptable number needed to screen. However, this approach failed to target subjects in the highest age groups and since almost two thirds of the subjects interested in the screening program failed to commence screening, approaches to increase this response (specifically in high-risk groups) needs to be explored. Funding Acknowledgement Type of funding sources: None.

In-utero exposure to air pollution and blood pressure in children from the Rhea birth cohort study, Greece

BACKGROUND AND AIM: High blood pressure (BP) in childhood has been linked with hypertension and impaired cardiovascular health within adulthood. Exposure to air pollution has been associated with elevated BP in children but only a few studies evaluated the persistence of these associations into early adolescence. We investigated the association between pregnancy exposure to air pollution and BP through childhood in the Rhea birth cohort in Greece. METHODS: Residential exposure to particulate matter <10 μm (PM10) and <2.5 μm (PM2.5) during pregnancy was estimated with temporally adjusted land-use regression models. We measured systolic (SBP) and diastolic (DBP) blood pressure at 4, 6, and 11 years. Hypertension was defined as DBP or SBP ≥95th sex-, age- and height-percentiles. Generalized estimating equation and multivariate regression models assessed the associations (per 5 µg/m³) with repeated and single time-point measures, respectively. We also tested effect modification by sex and maternal smoking. RESULTS: Median (IQR) levels of PM2.5 and PM10 during pregnancy were 14.4 (2.4) μg/m3 and 35.6 (2.3) μg/m3, respectively. PM10 was associated with higher SBP and DBP in boys but lower in girls (p-interaction= 0.025 and 0.036) at 4 years. We also observed higher risk for hypertension overall (1.62; 95% CI: 1.04, 2.53) and in boys (2.01; 95% CI: 1.07, 3.79), and in children born to non-smoking mothers during pregnancy (2.14; 95% CI: 1.25, 3.66). Higher PM2.5 was associated with lower SBP in boys at 6 (β= -3.75 mmHg; 95% CI: -7.14, -0.36) and 11 years (β= -4.49 mmHg; 95% CI: -9.09, 0.11; p-interaction= 0.068 and 0.072). Sex differences in BP trajectories were also observed. CONCLUSIONS: This study suggests that prenatal air pollution exposure may affect blood pressure during childhood. Further research is needed to understand sex differences and the role of co-exposure to maternal smoking. KEYWORDS: Blood pressure, childhood, air pollution, prenatal

Association of Prenatal Exposure to Persistent Organic Pollutants and Childhood Lipid Levels: The Rhea Birth Cohort (Greece)

BACKGROUND AND AIM: Lipid disorders in childhood are associated with an earlier onset and greater risk of cardiovascular disease in adulthood. Prenatal exposure to persistent organic pollutants (POPs) has been linked to cardiometabolic risk factors in childhood, but there are limited studies evaluating the persistence of these associations into early adolescence. We assessed the impact of in-utero exposure to POPs on lipid profiles during childhood in the RHEA birth cohort in Greece. METHODS: Maternal serum concentrations of several polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethene (DDE), and hexachlorobenzene (HCB) were measured in first trimester. We measured triglycerides (TG), total cholesterol (TC), HDL- and LDL-cholesterol at 4, 6, and 11 years. Generalized estimating equations and multivariate regression models assessed the associations with repeated and single time-point measures, respectively. We also tested effect modification by sex. RESULTS: We did not find any strong evidence of lipid levels at age-four being associated to prenatal POPs exposure. DDE exposure in the third tertile (>2846 ng/mL) was associated with higher TC (β= 8.01 mg/dL, 95% CI:1.66, 14.36), HDL (β= 3.25 mg/dL, 95% CI: 0.04, 6.46) and LDL (β= 6.29 mg/dL, 95% CI: 0.78, 11.79). HCB in the second tertile (69 – 102.5 ng/mL) was associated with lower TC (β= -7.27mg/dL, 95% CI: -13.36, -1.19) and HDL (β= -3.34 mg/dL, 95% CI: -6.40, -0.27). We observed strong negative associations between all POPs and age-six TG levels. Similarly, HCB and PCB118 were associated with lower TC and LDL levels at 11 years. In GEE models of repeated outcome measures DDE was associated with higher TC and HDL levels. No clear differences by sex were observed. CONCLUSIONS: Our data indicate that in utero exposures to POPs may be associated with changes in child circulating lipids. These findings require further exploration in other settings and larger cohorts. KEYWORDS: prenatal, POPs, lipids, children

Triglyceride-glucose index trajectory and arterial stiffness: results from Hanzhong Adolescent Hypertension Cohort Study

BackgroundThe triglyceride-glucose index (TyG index) has emerged as a reliable surrogate marker of insulin resistance associated with arterial stiffness. However, most studies were based on a cross-sectional design, and few studies have evaluated the longitudinal impact of the TyG index on arterial stiffness. This study aimed to investigate the associations of single time point measurement and the long-term trajectory of the TyG index with arterial stiffness in a Chinese cohort.MethodsData are derived from the Hanzhong Adolescent Hypertension Cohort study. A total of 2480 individuals who participated in the 2017 survey was included in the cross-sectional analysis. A sample of 180 individuals from the sub-cohort with follow-up data in 2005, 2013, and 2017 was enrolled in the longitudinal analysis. The TyG index was calculated as ln (fasting triglyceride [mg/dL] × fasting glucose [mg/dL]/2), and arterial stiffness was determined using brachial-ankle pulse wave velocity (baPWV). The latent class growth mixture modeling method was used to identify the TyG index trajectories from 2005 to 2017.ResultsIn the cross-sectional analysis, the median age of the study population was 42.8 (39.8, 44.9) years, and 1351 (54.5%) were males. Each one-unit increment in TyG index was associated with a 37.1 cm/s increase (95% confidence interval [CI] 23.7–50.6 cm/s; P < 0.001) in baPWV, and similar results were observed when the TyG index was in the form of quartiles. In the longitudinal analysis, we identified three distinct TyG index trajectories and found that the highest TyG index trajectory carried the greatest odds of increased arterial stiffness, with a fully adjusted odds ratio (OR) of 2.76 (95% CI 1.40, 7.54).ConclusionsElevated levels of baseline TyG index and higher long-term trajectory of TyG index were independently associated with increased arterial stiffness. Monitoring immediate levels and longitudinal trends of the TyG index may help with the prevention of arterial stiffness in the long run.

The association between trajectories of risk factors and risk of cardiovascular disease or mortality among patients with diabetes or hypertension: A systematic review.

IntroductionCardiometabolic risk factors and renal function are monitored regularly for patients with diabetes mellitus (DM)/ hypertension (HT). In addition to risk factor levels at a single time point, their trajectory (changes over time) can also be differentially related to the risk of cardiovascular diseases (CVD) and mortality. This study aimed to systematically examine the evidence regarding the association between risk factor trajectories and risk of CVD/mortality in patients with DM/HT.MethodPubMed, MEDLINE, and Embase were searched for articles from January 1963 to April 2021. Inclusion criteria: studies that 1) analyzed trajectories of risk factors including haemoglobin A1c (HbA1c), blood pressure, estimated glomerular filtration rate (eGFR), body mass index (BMI), and blood lipids; 2) were performed in the DM/HT population and, 3) included risk of CVD/mortality as outcomes. Study quality was assessed using the Newcastle-Ottawa quality assessment scale.ResultsA total of 22,099 articles were identified. After screening by title and abstract, 22,027 articles were excluded by irrelevant outcomes, exposure, population, or type of articles. Following full-text screening, 11 articles investigating the trajectories of HbA1c (N = 7), systolic blood pressure (SBP) (N = 3), and eGFR (N = 1) were included for data extraction and analysis. No studies were identified examining the association of BMI or lipid trajectories with CVD/mortality. All included studies were of good quality based on the NOS criteria. In general, stable trajectories within optimal ranges of the risk factors (HbA1c: <7%, SBP: 120-139mmHg, eGFR: >60mL/min/1.73m2) had the lowest CVD/mortality risk compared to an increasing HbA1c trajectory (from 8% to 10%), an increasing SBP trajectory (from 120–139 to ≥140mmHg), or a decreasing eGFR trajectory (from 90 to 70mL/min/1.73m2).ConclusionA relatively stable and well-controlled trajectory for cardiometabolic risk factors was associated with the lowest risk of CVD/mortality. Risk factor trajectories have important clinical implications in addition to single time point measurements. More attention should be given to patients with suboptimal control and those with unstable trends of cardiometabolic risk factors.

Estimating Rates of Switching Between Cell States Using a Single Time Point Measurement

In isogenic cell populations, cells can switch between different gene expression states. These expression states can be biologically relevant. For example, a certain expression state may cause a tumor cell to be resistant to treatment, while another state may leave it vulnerable to treatment. Estimating the rates of state-switching can be difficult, because experimentally measuring a cell's transcriptome often involves destroying the cell, so it can only be measured once. We propose a computational method to estimate the rate of switching between expression states, given data from a Luria-Delbrück style fluctuation test that requires only a single time point measurement. We then benchmark this method using simulated data to test its efficacy, with varying assumptions made about the cell cycle timing distribution in the simulations.

125. Dynamic PET facilitated Pharmacokinetic Modeling and High-dose Rifampin Regimens for Staphylococcus aureus Orthopedic Implant Associated Infections: Bench to Bedside

125. Dynamic PET facilitated Pharmacokinetic Modeling and High-dose Rifampin Regimens for <i>Staphylococcus aureus</i> Orthopedic Implant Associated Infections: Bench to Bedside

Temporal trends in canopy temperature and greenness are potential indicators of late-season drought avoidance and functional stay-green in wheat

The ability to avoid dehydration is a drought resistance mechanism becoming increasingly more important even in temperate regions. In wheat, dehydration avoidance can be associated with a maintained canopy cooling during dry periods. However, in an average year under temperate conditions, drought periods are rather short which makes it difficult to routinely screen for drought avoidance using canopy temperature (CT). Furthermore, confounding factors such as differences in height, shoot biomass, canopy structure and phenology complicate the interpretation of differences in CT. We aimed to use temporal trends in CT and canopy greenness during short-term drought and heat events in the early grain filling phase to circumvent these problems. During this phase, evaporative demand is high and phenology-driven senescence has yet little effect on CT. Diverse sets of 354 and 71 wheat genotypes where grown in the field phenotyping platform of ETH Zurich in 2018 and 2019, respectively. CT was repeatedly measured during early grain filling by means of drone-based imaging. The temporal trends in CT during early grain filling showed a moderate to high within-year heritability (h2 = 0.35 and h2 = 0.88 in 2018 and 2019, respectively). These trends were largely independent of confounding factors when compared to single time point measurements and likely represent genotype-specific reactions to decreasing water availability more directly than absolute CT. CT trends were also largely independent of the temporal trends in stay-green indices. Therefore, we used a combination of time-resolved CT and stay-green trends to identify genotypes combining both traits. Significant differences were observed in the combined time-resolved index among three replicated check varieties. We therefore propose to use the combined time-resolved index to identify genotypes with improved drought avoidance and functional stay green.

A Radioactive-Free Method for the Thorough Analysis of the Kinetics of Cell Cytotoxicity

The cytotoxic activity of T cells and Natural Killer cells is usually measured with the chromium release assay (CRA), which involves the use of 51Chromium (51Cr), a radioactive substance dangerous to the operator and expensive to handle and dismiss. The accuracy of the measurements depends on how well the target cells incorporate 51Cr during labelling which, in turn, depends on cellular division. Due to bystander metabolism, the target cells spontaneously release 51Cr, producing a high background noise. Alternative radioactive-free methods have been developed. Here, we compare a bioluminescence (BLI)-based and a carboxyfluorescein succinimidyl ester (CFSE)-based cytotoxicity assay to the standard radioactive CRA. In the first assay, the target cells stably express the enzyme luciferase, and vitality is measured by photon emission upon the addition of the substrate d-luciferin. In the second one, the target cells are labelled with CFSE, and the signal is detected by Flow Cytometry. We used these two protocols to measure cytotoxicity induced by treatment with NK cells. The cytotoxicity of NK cells was determined by adding increasing doses of human NK cells. The results obtained with the BLI method were consistent with those obtained with the CRA- or CFSE-based assays 4 hours after adding the NK cells. Most importantly, with the BLI assay, the kinetic of NK cells’ killing was thoroughly traced with multiple time point measurements, in contrast with the single time point measurement the other two methods allow, which unveiled additional information on NK cell killing pathways.

Kidney Tubulointerstitial Fibrosis and Tubular Secretion

Tubular secretion plays an important role in the efficient elimination of endogenous solutes and medications, and lower secretory clearance is associated with risk of kidney function decline. We evaluated whether histopathologic quantification of interstitial fibrosis and tubular atrophy (IFTA) is associated with lower tubular secretory clearance in persons undergoing kidney biopsy. Cross-sectional. The Boston Kidney Biopsy Cohort is a study of persons undergoing native kidney biopsies for clinical indications. Semiquantitative score of IFTA reported by 2 trained pathologists. We measured plasma and urine concentrations of 9 endogenous secretory solutes using a targeted liquid chromatography/mass spectrometry assay. We used linear regression to test associations of urine-to-plasma ratios (UPRs) of these solutes with IFTA score after controlling for estimated glomerular filtration rate (eGFR) and albuminuria. Among 418 participants, mean age was 53 years, 51% were women, 64% were White, and 18% were Black. Mean eGFR was 50mL/min/1.73m2, and median urinary albumin-creatinine ratio was 819mg/g. Compared with individuals with≤25% IFTA, those with>50% IFTA had 12%-37% lower UPRs for all 9 secretory solutes. Adjusting for age, sex, race, eGFR, and urine albumin and creatinine levels attenuated the associations, yet a trend of lower secretion across groups remained statistically significant (P<0.05 for trend) for 7 of 9 solutes. A standardized composite secretory score incorporating UPR for all 9 secretory solutes using the min-max method showed similar results (P<0.05 for trend). Single time point and spot measures of secretory solutes. Greater IFTA severity is associated with lower clearance of endogenous secretory solutes even after adjusting for eGFR and albuminuria.

Variability of multi-omics profiles in a population-based child cohort

BackgroundMultiple omics technologies are increasingly applied to detect early, subtle molecular responses to environmental stressors for future disease risk prevention. However, there is an urgent need for further evaluation of stability and variability of omics profiles in healthy individuals, especially during childhood.MethodsWe aimed to estimate intra-, inter-individual and cohort variability of multi-omics profiles (blood DNA methylation, gene expression, miRNA, proteins and serum and urine metabolites) measured 6 months apart in 156 healthy children from five European countries. We further performed a multi-omics network analysis to establish clusters of co-varying omics features and assessed the contribution of key variables (including biological traits and sample collection parameters) to omics variability.ResultsAll omics displayed a large range of intra- and inter-individual variability depending on each omics feature, although all presented a highest median intra-individual variability. DNA methylation was the most stable profile (median 37.6% inter-individual variability) while gene expression was the least stable (6.6%). Among the least stable features, we identified 1% cross-omics co-variation between CpGs and metabolites (e.g. glucose and CpGs related to obesity and type 2 diabetes). Explanatory variables, including age and body mass index (BMI), explained up to 9% of serum metabolite variability.ConclusionsMethylation and targeted serum metabolomics are the most reliable omics to implement in single time-point measurements in large cross-sectional studies. In the case of metabolomics, sample collection and individual traits (e.g. BMI) are important parameters to control for improved comparability, at the study design or analysis stage. This study will be valuable for the design and interpretation of epidemiological studies that aim to link omics signatures to disease, environmental exposures, or both.

Acute thalamic damage as a prognostic biomarker for post-traumatic epileptogenesis.

To identify magnetic resonance imaging (MRI) biomarkers for post-traumatic epilepsy. The EPITARGET (Targets and biomarkers for antiepileptogenesis, epitarget.eu) animal cohort completing T2 relaxation and diffusion tensor MRI follow-up and 1-month-long video-electroencephalography monitoring included 98 male Sprague-Dawley rats with traumatic brain injury and 18 controls. T2 imaging was performed on day (D) 2, D7, and D21 and diffusion tensor imaging (DTI) on D7 and D21 using a 7-Tesla Bruker PharmaScan MRI scanner. The mean and standard deviation (SD) of the T2 relaxation rate, multiple diffusivity measures, and diffusion anisotropy at each time-point within the ventroposterolateral and ventroposteromedial thalamus were used as predictor variables in multi-variable logistic regression models to distinguish rats with and without epilepsy. Twenty-nine percent (28/98) of the rats with traumatic brain injury (TBI) developed epilepsy. The best-performing logistic regression model utilized the D2 and D7 T2 relaxation time as well as the D7 diffusion tensor data. The model distinguished rats with and without epilepsy (Bonferroni-corrected p-value<.001) with a cross-validated concordance statistic of 0.74 (95% confidence interval [CI] 0.60-0.84). In a cross-validated classification test, the model exhibited 54% sensitivity and 91% specificity, enriching the epilepsy rate within the study population from the expected 29% to 71%. A model using the D2 T2 data only resulted in a 73% enriched epilepsy rate (regression p-value .007, cross-validated concordance 0.70, 95% CI 0.56-0.80, sensitivity 29%, specificity 96%). An MRI parameter set reporting on acute and subacute neuropathologic changes common to experimental and human TBI presents a diagnostic biomarker for post-traumatic epileptogenesis. Significant enrichment of the study population was achieved even when using a single time-point measurement, producing an expected epilepsy rate of 73%.

Stretchable Capacitive Pressure Sensing Sleeve Deployable onto Catheter Balloons towards Continuous Intra-Abdominal Pressure Monitoring.

Intra-abdominal pressure (IAP) is closely correlated with intra-abdominal hypertension (IAH) and abdominal compartment syndrome (ACS) diagnoses, indicating the need for continuous monitoring. Early intervention for IAH and ACS has been proven to reduce the rate of morbidity. However, the current IAP monitoring method is a tedious process with a long calibration time for a single time point measurement. Thus, there is the need for an efficient and continuous way of measuring IAP. Herein, a stretchable capacitive pressure sensor with controlled microstructures embedded into a cylindrical elastomeric mold, fabricated as a pressure sensing sleeve, is presented. The sensing sleeve can be readily deployed onto intrabody catheter balloons for pressure measurement at the site. The thin and highly conformable nature of the pressure sensing sleeve captures the pressure change without hindering the functionality of the foley catheter balloon.

Methodological and conceptual complexities of assessing relationships between single-occasion CRP inflammation and daily affect

Inflammation is commonly implicated in sustained levels of depressed mood, chiefly with concurrent measures. There is a dearth of research on understanding how mood-inflammation relationships change on a day-to-day timescale. Determining how inflammation and mood may fluctuate and interact with each other is imperative to determining which pathways may lead to a depressed mood due to inflammation, and, more broadly, which factors induce inflammation in the first place. Therefore, we explored a means of elucidating the nature of mood-inflammation relationships using daily measures of mood and a single time-point measure of inflammation, C-Reactive Protein (CRP). We predicted that the relationship between affect and this measure of inflammation would be time-invariant because of evidence suggesting factors contributing to inflammation are persistent over time, such as obesity or poor gut-microbiome health. Our sample consisted of 1397 young adult participants who completed daily surveys for thirteen days and provided a blood sample for CRP measurement once at the conclusion of the study. A Bayesian multivariate regression model was performed to determine how daily levels of positive and negative mood could be predicted by this single time-point measure of inflammation. As part of our analysis, we sought to control for two key moderators, BMI and physical activity. Results indicated that moderate levels of inflammation were not associated with poor mood when the individual exercised. We also determined that high BMI participants exhibited a greater impact of inflammation on their mood relative to low BMI participants. However, contrary to our primary prediction that this mood-inflammation relationship would be time-invariant, we did indeed find that the relationship was time-variant. This result indicated that research examining associations involving inflammation daily will be required to understand which causative factors may contribute to fluctuations of a mood-inflammation relationship on a daily basis.

Prenatal exposure to persistent organic pollutants and markers of obesity and cardiometabolic risk in Spanish adolescents

BackgroundPrenatal exposure to persistent organic pollutants (POPs) has been linked to cardiometabolic (CM) risk factors in childhood, but there are no studies evaluating the persistence of these associations into adolescence, a period of relevant changes in endocrine-dependent organ systems and rapid increases in lean and fat mass. We examined the associations of prenatal POP exposures with body mass index (BMI) from age 4 to 18 years, and with other CM risk markers in adolescence. MethodsWe analysed 379 children from the Spanish INMA-Menorca birth cohort study with measured cord blood POP concentrations. We calculated BMI z-scores at ages 4, 6, 11, 14 and 18 years using the WHO growth reference. Body fat % was measured at 11 and 18 years and waist-to-height ratio (WHtR) and blood pressure (BP) at 11, 14 and 18 years. We measured CM biomarkers in fasting blood collected at age 14 years and calculated a CM-risk score as the sum of the sex-, and age-specific z-scores for waist circumference, mean arterial BP, homeostatic model assessment of insulin resistance, fasting blood triglycerides, and high-density lipoprotein cholesterol (HDL-C) (n = 217). Generalised estimating equations and multivariate linear regression models assessed the associations with repeated and single time-point measures, respectively. ResultsHexachlorobenzene (HCB) exposure in the third tertile, compared to the first tertile, was associated with higher BMI (β = 0.24; 95% CI: 0.01, 0.47) and WHtR z-score (β = 0.27; 95% CI: 0.04, 0.51). A continuous increase in HCB was associated with an elevated body fat % (β per 10-fold increase = 4.21; 95% CI: 0.51, 7.92), systolic BP (β = 0.32; 95% CI: 0.02, 0.64) and diastolic BP z-score (β = 0.32; 95% CI: 0.02, 0.62) across all ages, and with higher CM-risk score (β = 1.59; 95% CI: 0.02, 3.18) and lipid biomarkers (total cholesterol, triglycerides and low-density lipoprotein cholesterol (LDL-C)) at 14 years. Dichlorodiphenyltrichloroethane (p,p’-DDT) exposure was non-monotonically associated with BMI and systolic BP. p,p’-DDE and Σ-polychlorinated biphenyls (PCBs) (sum of congeners 118, 138, 153, 180) were not associated with adiposity or BP. p,p’-DDT exposure was associated with an increased CM-risk score, and ΣPCBs concentrations with LDL-C in all adolescents and with total cholesterol only in girls (p-sex interaction = 0.05). ConclusionThis first longitudinal study from 4 to 18 years suggests that the previously reported POP associations with child BMI persist later in adolescence and that prenatal POP exposures are associated with major risk factors for adult CM syndrome.

Does psychological distress directly increase risk of incident cardiovascular disease? Evidence from a prospective cohort study using a longer-term measure of distress

ObjectiveCardiovascular disease (CVD) incidence is elevated among people with psychological distress. However, whether the relationship is causal is unclear, partly due to methodological limitations, including limited evidence relating to longer-term...

Resonant acoustic rheometry for non-contact characterization of viscoelastic biomaterials

Resonant Acoustic Rheometry (RAR) is a new, non-contact technique to characterize the mechanical properties of soft and viscoelastic biomaterials, such as hydrogels, that are used to mimic the extracellular matrix in tissue engineering. RAR uses a focused ultrasound pulse to generate a microscale perturbation at the sample surface and tracks the ensuing surface wave using pulse-echo ultrasound. The frequency spectrum of the resonant surface waves is analyzed to extract viscoelastic material properties. In this study, RAR was used to characterize fibrin, gelatin, and agarose hydrogels. Single time point measurements of gelled samples with static mechanical properties showed that RAR provided consistent quantitative data and measured intrinsic material characteristics independent of ultrasound parameters. RAR was also used to longitudinally track dynamic changes in viscoelastic properties over the course of fibrin gelation, revealing distinct phase and material property transitions. Application of RAR was verified using finite element modeling and the results were validated against rotational shear rheometry. Importantly, RAR circumvents some limitations of conventional rheology methods and can be performed in a high-throughput manner using conventional labware. Overall, these studies demonstrate that RAR can be a valuable tool to noninvasively quantify the viscoelastic mechanical properties of soft hydrogel biomaterials.