Plasma TMAO Research Articles

Plasma Trimethylamine N-Oxide and Its Precursors: Population Epidemiology, Parent-Child Concordance, and Associations with Reported Dietary Intake in 11- to 12-Year-Old Children and Their Parents.

BackgroundTrimethylamine N-oxide (TMAO) is a microbiome- and diet-derived metabolite implicated in adverse cardiovascular outcomes. To date, studies of plasma TMAO concentrations have largely focused on individuals with metabolic disease. As such, data on TMAO concentrations in population settings and parent–child dyads are lacking.ObjectivesThis study aimed to investigate parent–child concordance, age, and sex effects on plasma concentrations of TMAO and its precursors [l-carnitine, choline, betaine, and dimethylglycine (DMG)]. Associations between concentrations of TMAO and its precursors and self-reported dietary intakes of animal protein (i.e., red meat, meat products, chicken, fish, milk products, and cheese) and fast-food meals were also investigated.MethodsA total of 1166 children (mean ± SD age: 11 ± 0.5 y, 51% female) and 1324 parents (mean ± SD age: 44 ± 5.1 y, 87% female) had a biomedical assessment as part of Growing Up in Australia's Child Health Checkpoint. Plasma TMAO and precursor concentrations were quantified using ultra-high-pressure LC coupled with tandem MS.ResultsFamilial dyads significantly contributed to plasma TMAO and precursor concentrations (P < 0.0001), explaining 37% of variance for TMAO concentrations. Least-square mean ± SE plasma TMAO was lower in children (0.79 ± 0.02 µM on the log-scale) than in adults (1.22 ± 0.02 µM). By contrast, children's betaine (40.30 ± 0.34 µM) and DMG concentrations (1.02 ± 0.01 µM on the log-scale) were higher than adults’ betaine (37.50 ± 0.32 µM) and DMG concentrations (0.80 ± 0.01 µM) (P < 0.0001). Mean values of all metabolites, except adult TMAO, were higher in males than in females (P < 0.001). Greater reported intake of red meat and fish was associated with higher TMAO concentrations in both children [estimates (95% CIs) for red meat: 0.06 (0.01, 0.10); fish: 0.11 (0.06, 0.17)] and adults [red meat: 0.13 (0.08, 0.17); meat products: 0.07 (0.03, 0.12); and fish: 0.09 (0.04, 0.14)].ConclusionsAge, sex, and shared family factors, including diet, contribute to variation in plasma concentrations of TMAO and its precursors.

Free Choline, but Not Phosphatidylcholine, Elevates Circulating Trimethylamine-N-oxide and This Response Is Modified by the Gut Microbiota Composition in Healthy Men

Abstract Objectives Trimethylamine-N-oxide (TMAO), a choline-derived gut microbiota-dependent metabolite, is a newly recognized risk marker for cardiovascular disease. However, the contributions of different forms of choline and gut microbiota composition on TMAO production are largely unknown. The objectives of this study were to: 1) compare acute TMAO response to meals containing free choline (choline bitartrate) versus fat-soluble choline (phosphatidylcholine) and 2) to determine the effects of gut microbiota composition on TMAO response. Methods In a controlled, double-blinded, cross-over study, healthy men (n = 37) were provided meals containing (i) 600 mg choline as choline bitartrate (free choline); (ii) 600 mg choline as phosphatidylcholine; or (iii) no choline control in a random order. Blood and urine samples were collected at baseline and throughout the 6-h study period; a one-time stool sample was collected at baseline. Results Compared to no choline and phosphatidylcholine, free choline yielded 295% higher plasma TMAO (P = 0.002) and 250% higher urinary TMAO (P = 0.01), with no difference in TMAO response between phosphatidylcholine and no choline. High-TMAO producers (those with ≥40% increase in urinary TMAO response to free choline) had significantly different beta-diversity measures (unweighted UniFrac; PERMANOVA P = 0.01) compared to low-TMAO producers (those with &amp;lt;40% increase in TMAO response) but showed no difference in alpha-diversity. Analysis of Composition of Microbiomes (ANCOM) revealed that high-TMAO producers had more abundant lineages of Clostridium from Ruminococcaceae and Lachnospiraceae (in phylum Firmicutes) compared to low-TMAO producers (P &amp;lt; 0.05 with the strength of the ANCOM test W = 11 and W = 8, respectively). Conclusions Given that the majority of choline in food is in the form of phosphatidylcholine, the absence of TMAO elevation with phosphatidylcholine counters arguments that dietary choline should be avoided for TMAO-producing characteristics. Further, development of individualized dietary recommendations based on the gut microbiota composition may be a more appropriate strategy to reduce risk of cardiovascular disease. Funding Sources This research was supported by the Utah Agricultural Experiment Station Seed Grants Program.

Longitudinal Measures of Trimethylamine N-oxide and Incident Atherosclerotic Cardiovascular Disease Events in Older Adults: The Cardiovascular Health Study

Abstract Objectives Trimethylamine N-oxide (TMAO) is a gut microbiota-dependent metabolite of dietary choline, L-carnitine and phosphatidylcholine-rich animal foods. Based on experimental studies and cohorts with prevalent disease, elevated TMAO may increase risk of atherosclerotic cardiovascular disease (ASCVD). TMAO is also renally cleared and may interact with and causally contribute to renal dysfunction and elevated cystatin-C. Yet, the associations of serial TMAO levels with incident ASCVD in a community-based prospective cohort, and the potential mediating and modifying role of renal function, are not established. Methods We investigated the associations of serial measures of plasma TMAO, assessed at baseline and 7 years post baseline, with incident ASCVD among 4144 older adults in the Cardiovascular Health Study (CHS). TMAO was measured using stable isotope dilution LC/MS/MS (lab CV &amp;lt;6%). Incident ASCVD (myocardial infarction, fatal coronary heart disease, stroke, sudden cardiac death, or other atherosclerotic death) was centrally adjudicated using medical records. Risk was assessed by multivariable Cox proportional hazards regression including time-varying demographics, lifestyle factors, medical history, and laboratory and dietary variables. We assessed potential mediating effects and interaction by renal function estimated by cystatin-C. Results During a median 15 years follow-up, 1757 ASCVD events occurred. After multivariable adjustment, TMAO was associated with a higher risk of ASCVD, with an extreme quintile HR (95% CI) of 1.22 (1.04, 1.44), P-trend = 0.01. This relationship appeared further mediated or confounded by estimated glomerular filtration rate (eGFR): adjusting for cystatin-C-based eGFR, the HR (95% CI) was 1.06 (0.98–1.25). Significant interaction was also observed by renal function (P-interaction &amp;lt; 0.001), with TMAO associated with higher risk of ASCVD among individuals with impaired renal function (eGFR ≤ 60) [1.63 (1.03–2.59)], but not normal baseline renal function (eGFR &amp;gt; 60) [1.15 (0.96–1.37)], even with further adjustment for continuous eGFR. Conclusions In this large community-based cohort of older US adults, higher serial measures of TMAO were associated with an elevated risk of ASCVD, in particular among those with impaired renal function. Funding Sources NIH, NHLBI.

Association Between Plasma Trimethylamine N-oxide and Neoatherosclerosis in Patients With Very Late Stent Thrombosis

BackgroundTrimethylamine N-oxide (TMAO) has been shown to promote the development of atherosclerosis. However, the relationship between plasma TMAO and neoatherosclerosis, an important underlying mechanism of very late stent thrombosis (VLST), is unknown. MethodsThis post hoc study investigated the association between TMAO and neoatherosclerosis in 2 independent cohorts. These included a control group of 50 healthy volunteers and a study cohort of 50 patients with VLST who presented with ST-segment elevation myocardial infarction and underwent optical coherence tomography examination. Of the 50 patients with VLST, 23 had neoatherosclerosis and 27 did not have neoatherosclerosis. Patients with neoatherosclerosis were further divided into 2 subgroups, including 14 patients with plaque rupture and 9 without plaque rupture. ResultsThe plasma TMAO levels, detected using mass spectrometry, were significantly higher in patients with VLST than in healthy individuals (median [interquartile range], 2.50 [1.67-3.84] vs 1.32 [0.86-2.44] μM; P < 0.001). Among the patients with VLST, the plasma TMAO levels were significantly higher in patients with neoatherosclerosis than in those without neoatherosclerosis (3.69 [2.46-5.29] vs 1.96 [1.39-2.80] μM; P < 0.001). In addition, in patients with neoatherosclerosis, patients with plaque rupture had significantly higher plasma TMAO concentrations than those without plaque rupture (4.51 [3.41-5.85] vs 2.46 [2.05-3.55] μM; P = 0.005). Multivariate analysis indicated that TMAO was an independent predictor of neoatherosclerosis (odds ratio, 3.41; 95% confidence interval, 1.59-7.30; P = 0.002). Moreover, the area under the receiver operating characteristic curve for TMAO, differentiated by neoatherosclerosis, was 0.85. ConclusionsPlasma TMAO was significantly correlated with neoatherosclerosis and plaque rupture in patients with VLST.

P6509Plasma trimethylamine n-oxide level is associated with neoatherosclerosis in patients with very late stent thrombosis

Abstract Background Trimethylamine N-oxide (TMAO) has been demonstrated to promote the pathogenesis of atherosclerosis. It is unknown whether plasma TMAO is associated with neoatherosclerosis, an important underlying mechanism of very late stent thrombosis (VLST). We investigated the relationship between the culprit plaque morphology and plasma TMAO concentration in patients with ST-segment elevation myocardial infarction caused by VLST. Methods Optical coherence tomography (OCT) was used to evaluate the culprit lesion morphology. Thirty consecutive patients with VLST were enrolled; 17 patients were identified as neoatherosclerosis and 13 without neoatherosclerosis. Patients with neoatheroslcerosis were further divided into two subgroups, including 11 patients with plaque rupture and 6 without plaque rupture, respectively. Results The plasma TMAO levels were significantly higher in patients with VLST than in healthy individuals (3.64 μM [2.08–4.58] vs. 1.47 μM [0.89–2.75], p&lt;0.001). Within VLST patients, plasma TMAO levels were significantly higher in patients with neoatherosclerosis than in those without neoathersclerosis (4.35 μM [3.43–5.37] vs. 2.02 μM [1.30–3.59]; p&lt;0.001). The logistic analysis revealed that plasma TMAO was a predictor of neoatherosclerosis (odds ratio: 3.35, 95% confidence interval: 1.40–8.03; p=0.007). In addition, patients with neoatherosclerosis with plaque rupture had significantly elevated plasma TMAO concentration than those without plaque rupture (5.29 μM [4.35–7.21] vs. 3.63 μM [3.02–3.92]; p=0.012). The area under receiver operating characteristic curve for patients with neoatherosclerosis versus those without neoatherosclerosis was 0.87, the corresponding sensitivity and specificity was 0.77 and 0.88, respectively. The comparison of plasma TMAO level Conclusions High plasma TMAO was associated with neoatherosclerosis and plaque rupture in patients with VLST. Acknowledgement/Funding This study was supported by the Chinese Academy of Medical Sciences Innovation Fund for Medical Sciences (2016-I2M-1-009)

Is increased plasma TMAO a compensatory response to hydrostatic and osmotic stress in cardiovascular diseases?

Recent clinical studies show a positive correlation between elevated plasma TMAO and increased cardiovascular risk. However, the mechanism of the increase and biological effects of TMAO in the circulatory system are obscure.Plasma TMAO level depends mostly on the following three factors. First, the liver produces TMAO from TMA, a gut bacteria metabolite of dietary choline and carnitine. Second, plasma TMAO increases after ingestion of dietary TMAO from fish and seafood. Finally, plasma TMAO depends on TMAO and TMA excretion by the kidneys.Ample evidence highlights protective functions of TMAO, including the stabilization of proteins and cells exposed to hydrostatic and osmotic stresses, for example in fish exposed to hydrostatic stress (deep water) and osmotic stress (salty water).Osmotic stress and hydrostatic stresses are augmented in cardiovascular diseases such as hypertension. In hypertensive subjects a diastole-systole change in hydrostatic pressure in the heart may exceed 220 mmHg with a frequency of 60–220/min. This produces environment in which hydrostatic pressure changes over 100,000 times per 24 h. Furthermore, cardiovascular diseases are associated with disturbances in water-electrolyte balance which produce changes in plasma osmolarity. Perhaps, the increase in plasma TMAO in cardiovascular diseases is analogous to increased level of plasma natriuretic peptide B, which is both a cardiovascular risk marker and a compensatory response producing beneficial effects for pressure/volume overloaded heart. In this regard, there is some evidence that a moderate increase in plasma TMAO due to TMAO supplementation may be beneficial in animal model of hypertension-related heart failure. Finally, increased plasma TMAO is present in humans consuming seafood-rich diet which is thought to be health-beneficial.We hypothesize that increased plasma TMAO serves as a compensatory response mechanism which protects cells from hydrostatic and osmotic stresses.

A Randomized Controlled-feeding Trial Based on the Dietary Guidelines for Americans Does Not Affect Plasma Trimethylamine N-oxide Levels in Women (P08-031-19)

ObjectivesTrimethylamine N-oxide is a gut-mediated metabolite associated with cardiovascular disease. Acute diet challenges demonstrate that circulating TMAO concentrations are diet-responsive; however, long-term trials investigating how different dietary patterns affect circulating TMAO concentrations are sparse. The objective of the current study was to determine whether consumption of a diet patterned after the USDA’s 2010 Dietary Guidelines for Americans (DGA), as compared to the typical American Diet (TAD), would reduce plasma TMAO levels. MethodsA randomized, double-blind, controlled 8-wk intervention was conducted in overweight and obese women selected according to indexes of insulin resistance or dyslipidemia. Women were randomly assigned to the DGA or TAD group (n = 28 DGA and 24 TAD). The TAD diet was based on average adult intake from the NHANES 2009–2010. All foods and beverages were provided during the intervention and matched to each participant’s energy requirement to ensure maintenance of initial body weight. Plasma samples were collected at baseline, 1 wk of their typical diet, and after 2 and 8 weeks of dietary intervention, in an overnight-fasted condition, and utilized to quantitate circulating TMAO concentrations using stable isotope dilution chromatography tandem mass spectrometry. Statistical analysis were performed in SAS using analysis of covariance and partial correlation. ResultsFollowing 2 or 8 weeks of dietary intervention, plasma TMAO concentrations were not different between the DGA and TAD diets (3.45 ± 0.41 vs 2.91 ± 0.38 μM at week 2; 3.48 ± 0.41 vs 3.00 ± 0.40 μM at week 8, Mean ± SE, respectively). Post-intervention TMAO concentration was correlated to initial TMAO concentrations and body mass index but not age. Furthermore, we did not observe significant correlations between TMAO and measures of endothelial function (Endopat) or insulin resistance (HOMA-IR) which may reflect the relative health of the overall population enrolled in the study. ConclusionsConsumption of a diet based on the USDA’s 2010 Dietary Guidelines for Americansfor 8 weeks did not reduce plasma TMAO levels in this study. Funding SourcesSupported by National Dairy Council; Campbell Soup Co.; USDA-ARS Projects 2032-51530-022-00D and 6026-51000-010-05S.

Patent Highlights December 2018–January 2019

Patent Highlights December 2018–January 2019

Plasma TMAO and Choline Levels in Individuals With Metabolic Syndrome - Comparison Between Eggs and Choline Supplement.

Plasma TMAO and Choline Levels in Individuals With Metabolic Syndrome - Comparison Between Eggs and Choline Supplement.

Characteristics of Intestinal Microflora and Metabolites of Patients with Cranial Nerve Injury

As the study on microbiology deepens, human microorganism, especially intestinal microflora, has been proved to be closely related to the occurrence of many diseases. Cranial nerve injury diseases, especially large artery atherosclerosis, have a high incidence in China, which makes it the focus of disease prevention and control in China. However, no studies have been conducted on the intestinal microflora and plasma TMAO levels in patients with cranial nerve injury. In this study, the changes of intestinal microflora and its metabolites are analyzed by comparing blood and fresh stool samples from stroke patients and healthy people. The results of the study show that there are obvious disturbances in the intestinal microflora in patients with stroke, the proportion of harmful flora increases, and plasma TMAO levels decreases.

Fetal one-carbon nutrient concentrations may be affected by gestational diabetes

Both insufficiency and excess of one-carbon nutrients (folate, choline, vitamins B6 and B12) during pregnancy have been associated with gestational diabetes mellitus (GDM). However, the precise nature of this association has not been clearly established. We hypothesized that GDM may affect one-carbon nutrients concentrations in the fetus, thus possibly participating in epigenetic programing of the offspring. Maternal blood was collected at recruitment (12–16 weeks). At delivery (28–42 weeks), both maternal and cord blood were collected. Blood concentrations of one-carbon nutrients and their metabolites were compared between the two groups. A total of 368 women were included in the study, of whom 19 (5.6%) were later diagnosed with GDM. No significant differences were found in maternal blood concentrations of one-carbon nutrients and their metabolites between the GDM and control groups at recruitment or at delivery. In cord blood, however, serum folate (87.7 [IQR 70.4–103.9] vs 66.6 [IQR 45.5–80.3] nmol/L, P = .025) and plasma TMAO (2.82 [IQR 1.3–3.2] vs 1.35 [IQR 1.0–2.0] μmol/L, P = .017) concentrations were higher, while plasma betaine concentrations were lower (17.5 [IQR 16.3–19.4] vs 21.1 [IQR 18.0–24.1] μmol/L, P = .019) in infants born to mothers with GDM compared with control. Our data suggest that while maternal blood concentrations of one-carbon nutrients and their metabolites may not affect the risk of GDM, GDM may alter concentrations of serum folate, plasma betaine and TMAO in cord blood. These alterations in one-carbon nutrient concentrations in fetal circulation may impact epigenetic programing, thereby contributing to physiologic changes and disease susceptibility in adulthood associated with GDM offspring.

Inactivation mechanism of N61S mutant of human FMO3 towards trimethylamine

Human flavin-containing monooxygenase 3 (hFMO3) catalyses the oxygenation of a wide variety of compounds including drugs as well as dietary compounds. It is the major hepatic enzyme involved in the production of the N-oxide of trimethylamine (TMAO) and clinical studies have uncovered a striking correlation between plasma TMAO concentration and cardiovascular disease. Certain mutations within the hFMO3 gene cause defective trimethylamine (TMA) N-oxygenation leading to trimethylaminuria (TMAU) also known as fish-odour syndrome. In this paper, the inactivation mechanism of a TMAU-causing polymorphic variant, N61S, is investigated. Transient kinetic experiments show that this variant has a > 170-fold lower NADPH binding affinity than the wild type. Thermodynamic and spectroscopic experiments reveal that the poor NADP+ binding affinity accelerates the C4a-hydroperoxyFAD intermediate decay, responsible for an unfavourable oxygen transfer to the substrate. Steady-state kinetic experiments show significantly decreased N61S catalytic activity towards other substrates; methimazole, benzydamine and tamoxifen. The in vitro data are corroborated by in silico data where compared to the wild type enzyme, a hydrogen bond required for the stabilisation of the flavin intermediate is lacking. Taken together, the data presented reveal the molecular basis for the loss of function observed in N61S mutant.

Genome- and CD4+ T-cell methylome-wide association study of circulating trimethylamine-N-oxide in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN)

BackgroundTrimethylamine-N-oxide (TMAO), an atherogenic metabolite species, has emerged as a possible new risk factor for cardiovascular disease. Animal studies have shown that circulating TMAO levels are regulated by genetic and environmental factors. However, large-scale human studies have failed to replicate the observed genetic associations, and epigenetic factors such as DNA methylation have never been examined in relation to TMAO levels. Methods and resultsWe used data from the family-based Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) to investigate the heritable determinants of plasma TMAO in humans. TMAO was not associated with other plasma markers of cardiovascular disease, e.g. lipids or inflammatory cytokines. We first estimated TMAO heritability at 27%, indicating a moderate genetic influence. We used 1000 Genomes imputed data (n = 626) to estimate genome-wide associations with TMAO levels, adjusting for age, sex, family relationships, and study site. The genome-wide study yielded one significant hit at the genome-wide level, located in an intergenic region on chromosome 4. We subsequently quantified epigenome-wide DNA methylation using the Illumina Infinium array on CD4+ T-cells. We tested for association of methylation loci with circulating TMAO (n = 847), adjusting for age, sex, family relationships, and study site as the genome-wide study plus principal components capturing CD4+ T-cell purity. Upon adjusting for multiple testing, none of the epigenetic findings were statistically significant. ConclusionsOur findings contribute to the growing body of evidence suggesting that neither genetic nor epigenetic factors play a critical role in establishing circulating TMAO levels in humans.

Plasma Trimethylamine N-Oxide, a Gut Microbe–Generated Phosphatidylcholine Metabolite, Is Associated With Atherosclerotic Burden

BackgroundTrimethylamine N-oxide (TMAO), a gut microbiota metabolite from dietary phosphatidylcholine, has mechanistic links to atherosclerotic coronary artery disease (CAD) pathogenesis and is associated with adverse outcomes. ObjectivesThis study sought to examine the relationship between plasma TMAO levels and the complexity and burden of CAD and degree of subclinical myonecrosis. MethodsWe studied 353 consecutive stable patients with evidence of atherosclerotic CAD detected by elective coronary angiography between 2012 and 2014. Their high-sensitivity cardiac troponin T (hs-cTnT) levels were measured. SYNTAX (Synergy Between Percutaneous Coronary Intervention With Taxus and Cardiac Surgery) scores and lesion characteristics were used to quantify atherosclerotic burden. Fasting plasma TMAO was measured by mass spectrometry. ResultsIn this prospective cohort study, the median TMAO level was 5.5 μM (interquartile range [IQR]: 3.4 to 9.8 μM), the median SYNTAX score was 11.0 (IQR: 4.0 to 18.5), and 289 (81.9%), 40 (11.3%), and 24 (6.8%) patients had low (0 to 22), intermediate (23 to 32), and high (≥33) SYNTAX scores, respectively. Plasma TMAO levels correlated (all p < 0.0001) with the SYNTAX score (r = 0.61), SYNTAX score II (r = 0.62), and hs-cTnT (r = 0.29). Adjusting for traditional risk factors, body mass index, medications, lesion characteristic, renal function, and high-sensitivity C-reactive protein, elevated TMAO levels remained independently associated with a higher SYNTAX score (odds ratio [OR]: 4.82; p < 0.0001), SYNTAX score II (OR: 1.88; p = 0.0001), but were not associated with subclinical myonecrosis (OR: 1.14; p = 0.3147). Elevated TMAO level was an independent predictor of the presence of diffuse lesions, even after adjustments for traditional risk factors and for hs-cTnT (OR: 2.05; 95% confidence interval: 1.45 to 2.90; p = 0.0001). ConclusionsFasting plasma TMAO levels are an independent predictor of a high atherosclerotic burden in patients with CAD.

Intestinal Microbiota-Dependent Phosphatidylcholine Metabolites, Diastolic Dysfunction, and Adverse Clinical Outcomes in Chronic Systolic Heart Failure

BackgroundTrimethylamine-N-oxide (TMAO) has been linked to increased cardiovascular risk. We aimed to determine the prognostic value of TMAO and its dietary precursors, choline and betaine, in heart failure (HF). Methods and ResultsIn 112 patients with chronic systolic HF with comprehensive echocardiographic evaluation, we measured plasma TMAO, choline, and betaine by mass spectrometry. Median (interquartile range) TMAO levels, choline, and betaine levels were 5.8 (3.6–12.1) μmol/L, 10.9 (8.4–14.0) μmol/L, and 43.8 (37.1–53.0) μmol/L, respectively, and were correlated with each other (all P < .0001 for both). TMAO levels were significantly higher in patients with diabetes mellitus (9.4 [4.9–13.2] vs 4.8 [3.4–9.8] μmol/L; P = .005) and in subjects with New York Heart Association functional class III or greater (7.0 [4.7–14.8] vs 4.7 [3.4–11.3] μmol/L; P = .02). Elevated TMAO, choline, and betaine levels were each associated with higher plasma N-terminal pro–B-type natriuretic peptide (NT-proBNP) levels and more advanced left ventricular diastolic dysfunction, but not systolic dysfunction or inflammatory and endothelial biomarkers. Higher choline (hazard ratio [HR] 1.64, 95% CI 1.22–2.20; P = .001), betaine (HR 1.51, 95% CI 1.10–2.08; P = .01), and TMAO (HR 1.48, 95% CI 1.10–1.96; P = .01) predicted increased risk for 5-year adverse clinical events (death/transplantation). Only higher TMAO levels predicted incident adverse clinical events independently from age, estimated glomerular filtration rate, mitral E/septal Ea, and NT-proBNP levels (HR 1.46, 95% CI 1.03–2.14; P = .03). ConclusionElevated plasma TMAO, choline, and betaine levels are each associated with more advanced left ventricular diastolic dysfunction and portend poorer long-term adverse clinical outcomes in chronic systolic HF. However, only higher plasma TMAO was associated with poor prognosis after adjustment for cardiorenal indices.

Metabolic Biomarkers of Prenatal Disorders: An Exploratory NMR Metabonomics Study of Second Trimester Maternal Urine and Blood Plasma

This work describes an exploratory NMR metabonomic study of second trimester maternal urine and plasma, in an attempt to characterize the metabolic changes underlying prenatal disorders and identify possible early biomarkers. Fetal malformations have the strongest metabolic impact in both biofluids, suggesting effects due to hypoxia (leading to hypoxanthine increased excretion) and a need for enhanced gluconeogenesis, with higher ketone bodies (acetone and 3-hydroxybutyric acid) production and TCA cycle demand (suggested by glucogenic amino acids and cis-aconitate overproduction). Choline and nucleotide metabolisms also seem affected and a distinct plasma lipids profile is observed for mothers with fetuses affected by central nervous system malformations. Urine from women who subsequently develop gestational diabetes mellitus exhibits higher 3-hydroxyisovalerate and 2-hydroxyisobutyrate levels, probably due to altered biotin status and amino acid and/or gut metabolisms (the latter possibly related to higher BMI values). Other urinary changes suggest choline and nucleotide metabolic alterations, whereas lower plasma betaine and TMAO levels are found. Chromosomal disorders and pre-preterm delivery groups show urinary changes in choline and, in the latter case, in 2-hydroxyisobutyrate. These results show that NMR metabonomics of maternal biofluids enables the noninvasive detection of metabolic changes associated to prenatal disorders, thus unveiling potential disorder biomarkers.

Copper toxicity in the spiny dogfish ( Squalus acanthias): Urea loss contributes to the osmoregulatory disturbance

Previous research showed that the spiny dogfish, Squalus acanthias, is much more sensitive to silver exposure than typical marine teleosts. The aim of the present study was to investigate if spiny dogfish were equally sensitive to copper exposure and whether the toxic mechanisms were the same. We exposed cannulated and non-cannulated spiny dogfish to measured concentrations of Cu (nominally 0, 500, 1000 and 1500 μg L −1 Cu) for 72–96 h. All Cu exposures induced acidosis and lactate accumulation of either a temporary (500 μg L −1) or more persistent nature (1000 and 1500 μg L −1). At the two highest Cu concentrations, gill Na +/K +-ATPase activities were reduced by 45% (1000 μg L −1) and 62% (1500 μg L −1), and plasma Na + and Cl − concentrations increased by approximately 50 mM each. At the same time urea excretion doubled and plasma urea dropped by ∼100 mM. Together with plasma urea, plasma TMAO levels dropped proportionally, indicating that the general impermeability of the gills was compromised. Overall plasma osmolarity did not change. Cu accumulation was limited with significant increases in plasma Cu and elevated gill and kidney Cu burdens at 1000 and 1500 μg L −1. We conclude that Cu, like Ag, exerts toxic effect on Na +/K +-ATPase activities in the shark similar to those of teleosts, but there is an additional toxic action on elasmobranch urea retention capacities. With a 96 h LC 50 in the 800–1000 μg L −1 range, overall sensitivity of spiny dogfish for Cu is, in contrast with its sensitivity to Ag, only slightly lower than in typical marine teleosts.