N-Terminal Pro-Brain Type Natriuretic Peptide Predicts Cardiovascular Events Independently of Arterial Stiffness, Assessed By Carotid-to-Femoral Pulse Wave Velocity, in Apparently Healthy Subjects.

AIM: This study aimed to evaluate whether N-terminal pro-brain natriuretic peptide (NT-proBNP) and carotid-to-femoral pulse wave velocity (PWV) carried independent prognostic value in predicting cardiovascular events in apparently healthy individuals beyond traditional risk factors. METHODS: A total of 1,872 participants aged 41, 51, 61, or 71 years from the MONItoring of trends and determinants in CArdiovascular disease (MONICA) study were included. Traditional risk factors were assessed, including: smoking status; mean systolic and diastolic blood pressure; body mass index; fasting plasma glucose; serum triglycerides; total, high-density, and low-density lipoprotein cholesterol; NT-proBNP; and PWV. The principal endpoint that was assessed during 16 years of follow-up was a composite of major adverse cardiovascular events (MACE). The secondary endpoints were cardiovascular mortality (CVM), hospitalisation for coronary artery disease (CAD), and a composite of hospitalisation for heart failure (HF) or atrial fibrillation (AF). RESULTS: At baseline, NT-proBNP was associated with PWV (ß=0.14; p<0.001), but not after adjustment for traditional risk factors (ß=-0.01; p=0.67). In models including traditional risk factors and PWV, NT-proBNP was associated with all four outcomes (HRMACE=1.33, 95% CI 1.16-1.52; HRCVM=2.02, 95% CI 1.65-2.48; HRCAD=1.29, 95% CI 1.07-1.55; and HRHF or AF=1.79, 95% CI 1.40-2.28). In the same model, PWV was only associated with CVM (HRCVM=1.20, 95% CI 1.01-1.41). No interactions between NT-proBNP and PWV were found. N-terminal pro-brain natriuretic peptide significantly improved net reclassification (NRI) for MACE (NRI=0.12; p=0.03), CVM (NRI=0.33; p<0.001), and HF or AF (NRI=0.33; p<0.001) beyond traditional risk factors, while PWV did not aid in net reclassification improvement for any endpoint. CONCLUSIONS: In apparently healthy individuals, NT-proBNP and PWV predicted cardiovascular events independently. N-terminal pro-brain natriuretic peptide improved reclassification for the prediction of MACE, CVM, and hospitalisation for HF or AF beyond traditional risk factors, while PWV did not.

Lifetime costs and lifetime net public expenditures of smoking.

BACKGROUND: Current estimates of lifetime costs of smoking are largely based on model analyses using etiologic fractions for a variety of diseases or Markov chain models. Direct estimation studies based on individual data for health costs by smoking status over a lifetime are non-existent. METHODS: We estimated lifetime costs in a societal perspective of 18-year-old daily-smokers (continuing smoking throughout adult life) and never-smokers in Denmark, as well as lifetime public expenditures in the two groups. Main outcomes were lifetime net public expenditures and lifetime health costs according to OECD definitions and lifetime earned incomes. Estimates of these outcomes were based on registries containing individual-level data. Confounder-adjusted differences between daily-smokers and never-smokers were interpreted as smoking-attributable lifetime public expenditures and costs. RESULTS: The net lifetime public expenditure is, on average, €20 520 higher for male 18-year-old daily-smokers than for never-smokers, but €9771 lower, for female daily-smokers compared with never-smokers. In male 18-year-old daily-smokers, average lifetime health costs are €9921 higher and average lifetime earned incomes are €91 159 lower than for never-smokers. The corresponding figures are €5849 higher and €23 928 lower, respectively, for women. CONCLUSION: 18-year-old male daily-smokers are net public spenders over their lifetime compared with never-smokers, while the opposite applies for women. In Denmark, smoking is associated with higher lifetime health costs for society and losses in earned incomes-both for men and women.

Sex- and age-related differences in the predictive capability of circulating biomarkers: from the MONICA 10 cohort.

OBJECTIVES: The purpose of this study was to assess whether high-sensitivity C-reactive protein (hs-CRP), N-terminal pro-brain natriuretic peptide (NT-proBNP), and soluble urokinase plasminogen activator receptor (suPAR) differed in their ability to predict cardiovascular outcomes beyond traditional risk factors in younger and older men and women without known cardiovascular disease. Design. Prospective population-based cohort study of 1951 individuals from the MONItoring of trends and determinants in Cardiovascular disease (MONICA) study, examined 1993-1994. Participants were stratified into four groups based on sex and age. Subjects aged 41 or 51 years were classified as younger; those aged 61 or 71 years were classified as older. The principal endpoint was death from cardiovascular causes. Predictive capabilities of biomarkers were tested using Cox proportional-hazards regression, Harrell's concordance-index, net reclassification improvement, and classification and regression tree (CART) analysis. Results. Median follow-up was 18.5 years, during which 19/597 younger men, 100/380 older men, 12/607 younger women, and 46/367 older women had died from a cardiovascular cause. NT-proBNP was independently associated with death from cardiovascular causes among all participants (p ≤ .02) except younger women (p = .70), whereas hs-CRP was associated with this endpoint in men (p ≤ .007), and suPAR in older men only (p < .001). None of the biomarkers improved discrimination ability beyond traditional risk factors (p ≥ .07). However, NT-proBNP enhanced reclassification in men and older women. CART-analysis showed that NT-proBNP was generally of greater value among men, and suPAR among women. Conclusions. Hs-CRP, NT-proBNP, and suPAR displayed different associations with cardiovascular death among apparently healthy younger and older men and women.

Association between antecedent blood pressure, hypertension-mediated organ damage and cardiovascular outcome.

Purpose: The objective of this study was to test if combining antecedent systolic blood pressure (SBP) with traditional risk factors and hypertension-mediated organ damage (HMOD) improves risk stratification for subsequent cardiovascular disease.Materials and methods: 1910 subjects participated in this study. Antecedent SBP was defined as the average of measurements obtained in 1982 and in 1987. Current SBP was obtained in 1993. HMOD were examined in 1993. HMOD was defined as either atherosclerotic plaque(s), increased pulse wave velocity, increased urine albumin creatinine ratio (above the 90th percentile) or left ventricular hypertrophy. Major adverse cardiovascular events (MACE) including myocardial infarction, cerebrovascular disease, heart failure and arrhythmia were obtained from national registries.Results: Subjects were divided into two age categories: a middle-aged group (aged 41 or 51) and an older group (aged 61 or 71). From 1993 to 2010, 425 events were observed. In multivariable analysis with both current and antecedent SBP adjusted for traditional risk factors, current SBP was associated with each measure of HMOD whilst antecedent SBP was not significantly associated with urine albumin creatinine ratio in the older group, LVMI in the middle-aged group, or the presence of plaque in any of the age groups (all p > 0.15). When current and antecedent SBP were evaluated together, current SBP was not associated with MACE in the middle-aged subgroup [HR = 1.09 (0.96-1.22), p = 0.18] but remained associated with MACE in the older subgroup [HR = 1.21 (1.10-1.34), p < 0.01]. Contrariwise, antecedent SBP was only associated with MACE in the middle-aged subgroup [HR = 1.24 (1.04-1.48), p = 0.02]. Adding antecedent SBP to traditional risk factors did not improve the predictive accuracy of the survival model.Conclusion: In healthy non-medicated middle-aged subjects, antecedent SBP is associated with cardiovascular outcome independently of current BP, traditional risk factors and HMOD. However, improvement in risk stratification seems to be limited.

Medication-Focused Patient Counseling Upon Discharge: A Feasibility Study of Effect on Patient Satisfaction.

OBJECTIVE: To develop and test a simple medication-focused patient counseling intervention at hospital discharge, with the aim of improving patient satisfaction. METHODS: The intervention was developed during a workshop and carried out by pharmaconomists. The final intervention comprised preparing information for the discharge counseling, medication reconciliation, discussion with physician, patient counseling at discharge, medication report to primary care physician, and phone follow-up three days after discharge. The intervention was tested against usual care in a gastrointestinal surgical unit in a feasibility study, using the setup of a randomized controlled trial, with patient satisfaction as the primary outcome. RESULTS: A total of 85 patients were invited to participate in the study. Following refusals (n = 11) and exclusions (n = 10), 32 patients were included in each trial arm (median age of 66.5 years; 52% males; median admission length of seven days). Patient satisfaction was high in both groups, with 75% (intervention) and 91% (control) reporting being overall satisfied with the discharge process (p = 0.10). No other differences between the groups were identified. CONCLUSIONS: The intervention did not result in improved patient satisfaction. This is likely attributed to the low number of patients included, the high satisfaction at baseline, and the lack of a validated tool to measure patient satisfaction. The developed intervention and study findings can inform future studies.

Circulating biomarkers for long-term cardiovascular risk stratification in apparently healthy individuals from the MONICA 10 cohort.

AIMS: The aim of this study was to examine whether high-sensitivity C-reactive protein (hs-CRP), N-terminal pro-brain natriuretic peptide (NT-proBNP), and soluble urokinase plasminogen activator receptor (suPAR) carried incremental prognostic value in predicting cardiovascular morbidity and mortality beyond traditional risk factors in apparently healthy individuals. METHODS AND RESULTS: This was a prospective population-based cohort study comprising 1951 subjects included in the 10-year follow-up of the MONItoring of trends and determinants in CArdiovascular disease (MONICA) study, between 1993 and 1994. The principal endpoint was death from cardiovascular causes. Secondary endpoints were death from any cause, coronary artery disease, heart failure, and cerebrovascular disease. Predictive capabilities of each of the three biomarkers were tested using Cox proportional-hazards regression, Harrell's concordance index (C-index), and net reclassification improvement (NRI). Study participants were aged 41, 51, 61, or 71 years, and equally distributed between the two sexes. During a median follow-up of 18.5 years (interquartile range: 18.1-19.0), 177 (9.1%) subjects died from a cardiovascular cause. Hs-CRP (adjusted standardized hazard ratio (HR): 1.37, 95% confidence interval (CI): 1.17-1.60), NT-proBNP (HR: 1.90, 95% CI: 1.58-2.29), and suPAR (HR: 1.35, 95% CI: 1.17-1.57) were all significantly associated with cardiovascular deaths after adjustment for age, sex, smoking status, systolic blood pressure, and total cholesterol (p < 0.001 for all). Furthermore, all three biomarkers were significantly associated with significant NRI. However, only NT-proBNP significantly raised the C-index in predicting death from cardiovascular causes when added to the risk factors (C-index 0.860 versus 0.847; p = 0.02). CONCLUSIONS: Hs-CRP, suPAR, and particularly NT-proBNP predicted cardiovascular death and may enhance prognostication beyond traditional risk factors in apparently healthy individuals.

A large-scale metabolomics study to harness chemical diversity and explore biochemical mechanisms in ryegrass.

Perennial ryegrass (Lolium perenne) is integral to temperate pastoral agriculture, which contributes most of the milk and meat production worldwide. Chemical profiles and diversity of ryegrass offer several opportunities to harness specific traits and elucidate underlying biological mechanisms for forage improvement. We conducted a large-scale metabolomics study of perennial ryegrass comprising 715 genotypes, representing 118 populations from 21 countries. Liquid/gas chromatography-mass spectrometry based targeted and non-targeted techniques were used to analyse fructan oligosaccharides, lipids, fatty acid methyl esters, polar and semi-polar compounds. Fructan diversity across all genotypes was evaluated, high- and low-sugar groups identified, and fructan accumulation mechanisms explored. Metabolites differentiating the two groups were characterised, modules and pathways they represent deduced, and finally, visualisation and interpretation provided in a biological context. We also demonstrate a workflow for large-scale metabolomics studies from raw data through to statistical and pathway analysis. Raw files and metadata are available at the MetaboLights database.

Impact of age on the association between 24-h ambulatory blood pressure measurements and target organ damage.

OBJECTIVE: The aim of this study was to evaluate the impact of age on the associations between hemodynamic components derived from 24-h ambulatory blood pressure (24-h ABPM) and target organ damage, in apparently healthy, nonmedicated individuals. METHODS: Twenty-four-hour ABPM and target organ damage (left ventricular mass index, pulse wave velocity, urine albumin : creatinine ratio and carotid atherosclerotic plaques) were evaluated in 1408 individuals. Associations were examined in regression models, stratified for age [middle-aged (41 or 51 years) or elderly (61 or 71 years)], and adjusted for sex, smoking status, and total-cholesterol. RESULTS: In middle-aged individuals, an increase of 10 mmHg in 24-h SBP was independently associated with an increase of 3.8 (2.7-4.8) g/m in LVMI. The effect was nearly doubled in the elderly subgroup, where the same increase resulted in an increase in LVMI of 6.3 (5.0-7.6) g/m (P for interaction <0.01). An increase of 10 mmHg of 24-h SBP was associated with a 6.7% increase in pulse wave velocity in middle-aged individuals and with an 9.1% increase in elderly individuals (P for interaction <0.01). An independent association between 24-h ABPM and urine albumin : creatinine ratio was only observed in the elderly subgroup. Associations between the presence of atherosclerotic plaques and components from 24-h ABPM except 24-h DBP were not modified by age (all P for interaction >0.26). CONCLUSION: Age enhances the associations between hemodynamic components obtained from 24-h ABPM and measures of arterial stiffness, microvascular damage, and cardiac structure, but not atherosclerosis.

Costs associated with adverse events among acute patients.

BACKGROUND: The aim of this study was to analyse the additional treatment costs of acute patients admitted to a Danish hospital who suffered an adverse event (AE) during in-hospital treatment. METHODS: A matched case-control design was utilised. Using a combination of trigger words and patient record reviews 91 patients exposed to AEs were identified. Controls were identified among patients admitted to the same department during the same 20-month period. The matching was based on age, gender, and main diagnosis. Cost data was extracted from the Danish National Cost Database for four different periods after beginning of the admission. RESULTS: Patients exposed to an AE were associated with higher mean cost of EUR 9505 during their index admission (p = 0.014). For the period of 6 months from the beginning of the admission minus the admission itself they were associated with higher mean cost of EUR 4968 (p = 0.016). For the period from the 7th month until the end of the 12th month there was no statistically significant difference (p = 0.104). For the total period of 12 month, patients exposed to an AE were associated with statistically significant higher mean cost of EUR 13,930 (p = 0.001). CONCLUSIONS: AEs are associated with significant hospital costs. Our findings suggest that a follow-up period of 6 months is necessary when investigating the costs associated with AEs among acute patients. Further research of specific types of AEs and the costs of preventing these types of AEs would improve the understanding of the relationship between adverse events and costs.

Impact of Age and Target-Organ Damage on Prognostic Value of 24-Hour Ambulatory Blood Pressure.

Markers of target-organ damage and 24-hour ambulatory blood pressure (BP) measurement improve cardiovascular risk stratification. The prevalence of target-organ damage and raised BP increases with aging. The study aim was to evaluate the impact of age and target-organ damage on the prognostic value of ambulatory BP. Markers of target-organ damage and ambulatory BP were measured in 1408 healthy people aged 41 or 51 (middle-aged group), and 61 or 71 (older group) years. The primary outcome was cardiovascular events after 16 years of follow-up, with data obtained from national registries. The prognostic value of BP was evaluated with Cox regression models, adjusted for traditional risk factors and target-organ damage, including left ventricular mass, pulse wave velocity, carotid plaques, and urine albumin/creatinine ratio. A total of 323 events were observed. In comparison with traditional risk factors, adding systolic BP and presence of target-organ damage improved risk stratification by increasing concordance index from 0.711 to 0.728 (P=0.01). In middle-aged subjects with target-organ damage, increment in pulse pressure (hazard ratio, 1.70; 95% confidence interval, 1.31-2.21; P<0.01) and increment in average real variability (hazard ratio, 1.29; 95% confidence interval, 1.05-1.59; P=0.02) were associated with a greater risk of cardiovascular disease compared with subjects without target-organ damage: hazard ratio, 1.04 (95% confidence interval, 0.74-1.46; P=0.81); P for interaction, 0.02; and hazard ratio, 0.89 (95% confidence interval, 0.69-1.14; P=0.36); P for interaction, 0.01. Target-organ damage may be a marker of individual susceptibility to the harmful effects of pulse pressure and BP variability on the cardiovascular system in middle-aged individuals.

Elevated estimated arterial age is associated with metabolic syndrome and low-grade inflammation.

BACKGROUND: Arterial age can be estimated from equations relating arterial stiffness to age and blood pressure in large cohorts. We investigated whether estimated arterial age (eAA) was elevated in patients with the metabolic syndrome and/or known cardiovascular disease (CVD), which factors were associated with eAA and whether eAA added prognostic information. METHODS: In 1993, 2366 study participants, 41, 51, 61, and 71 years old, had traditional cardiovascular risk factors and carotid-femoral pulse wave velocity (cfPWV) measured. Risk groups were identified based on known CVD and components of metabolic syndrome, Systematic COronary Risk Evaluation, or Framingham risk score. From age, mean blood pressure, and cfPWV, eAA and estimated cfPWV (ePWV) were calculated. In 2006, the combined cardiovascular endpoint (CEP) of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and hospitalization for ischemic heart disease was registered. RESULTS: cfPWV and ePWV increased with ageing and cardiovascular risk (all P < 0.001), but ePWV increased more with ageing than cfPWV. The difference between eAA and chronological age was associated with male sex (ß = 0.14), higher heart rate (ß = 0.16 both P < 0.001), fasting glucose (ß = 0.08) soluble urokinase plasminogen activator receptor (ß = 0.06, both P < 0.01), and known CVD (ß = 0.06, P < 0.05) independently of age, SBP, and heart rate. Independently of Systematic COronary Risk Evaluation, eAA (hazard ratio = 1.20, P < 0.01) predicted CEP, but not as accurately as ePWV (hazard ratio = 1.58, P < 0.001) and cfPWV (hazard ratio = 1.32, P < 0.001) among apparently healthy study participants. CONCLUSION: Elevated eAA was associated with male sex, higher plasma glucose, and soluble urokinase plasminogen activator receptor and known CVD independently of age, SBP, and heart rate.

Estimated carotid-femoral pulse wave velocity has similar predictive value as measured carotid-femoral pulse wave velocity.

BACKGROUND: Carotid-femoral pulse wave velocity (cfPWV) adds significantly to traditional cardiovascular risk prediction, but is not widely available. Therefore, it would be helpful if cfPWV could be replaced by an estimated carotid-femoral pulse wave velocity (ePWV) using age and mean blood pressure, and previously published equations. The aim of this study was to investigate whether ePWV could predict cardiovascular events independently of traditional cardiovascular risk factors and/or cfPWV. METHOD: cfPWV was measured and ePWV was calculated in 2366 patients from four age groups of the Danish MONICA10 cohort. Additionally, the patients were divided into four cardiovascular risk groups based on Systematic COronary Risk Evaluation (SCORE) or Framingham risk score (FRS). In 2006, the combined cardiovascular endpoint of cardiovascular death, nonfatal myocardial infarction, stroke and hospitalization for ischemic heart disease was registered. RESULTS: Most results were retested in 1045 hypertensive patients from a Paris cohort. Bland-Altman plot demonstrated a relative difference of -0.3% [95% confidence interval (CI) -15 to 17%] between ePWV and cfPWV. In Cox regression models in apparently healthy patients, ePWV and cfPWV (per SD) added independently to SCORE in prediction of combined endpoint [hazard ratio (95%CI) = 1.38(1.09-1.76) and hazard ratio (95%CI) = 1.18(1.01-1.38)] and to FRS [hazard ratio (95%CI) = 1.33(1.06-1.66) and hazard ratio (95%CI) = 1.16(0.99-1.37)]. If healthy patients with ePWV and/or cfPWV at least 10 m/s were reclassified to a higher SCORE risk category, net reclassification index was 10.8%, P less than 0.01. These results were reproduced in the Paris cohort. CONCLUSION: ePWV predicted major cardiovascular events independently of SCORE, FRS and cfPWV indicating that these traditional risk scores have underestimated the complicated impact of age and blood pressure on arterial stiffness and cardiovascular risk.

Does gibberellin biosynthesis play a critical role in the growth of Lolium perenne? Evidence from a transcriptional analysis of gibberellin and carbohydrate metabolic genes after defoliation.

Global meat and milk production depends to a large extent on grazed pastures, with Lolium perenne being the major forage grass in temperate regions. Defoliation and subsequent regrowth of leaf blades is a major and essential event with respect to L. perenne growth and productivity. Following defoliation, carbohydrates (mainly fructans and sucrose) have to be mobilized from heterotrophic tissues to provide energy and carbon for regrowth of photosynthetic tissues. This mobilization of reserve carbohydrates requires a substantial change in the expression of genes coding for enzymes involved in carbohydrate metabolism. Here we tested the hypothesis that gibberellins (GA) are at the core of the processes regulating the expression of these genes. Thus, we examined the transcript profiles of genes involved in carbohydrate and GA metabolic pathways across a time course regrowth experiment. Our results show that following defoliation, the immediate reduction of carbohydrate concentrations in growing tissues is associated with a concomitant increase in the expression of genes encoding carbohydrate mobilizing invertases, and was also associated with a strong decrease in the expression of fructan synthesizing fructosyltransferase genes. We also show that the decrease in fructan levels is preceded by increased expression of the GA activating gene GA 3-oxidase and decreased expression of the GA inactivating gene GA 2 -oxidase in sheaths. GA 3-oxidase expression was negatively, while GA 2 -oxidase positively linked to sucrose concentrations. This study provides indicative evidence that gibberellins might play a role in L. perenne regrowth following defoliation and we hypothesize that there is a link between gibberellin regulation and sugar metabolism in L. perenne.

Home Care Providers to the Rescue: A Novel First-Responder Programme.

AIM: To describe the implementation of a novel first-responder programme in which home care providers equipped with automated external defibrillators (AEDs) were dispatched in parallel with existing emergency medical services in the event of a suspected out-of-hospital cardiac arrest (OHCA). METHODS: We evaluated a one-year prospective study that trained home care providers in performing cardiopulmonary resuscitation (CPR) and using an AED in cases of suspected OHCA. Data were collected from cardiac arrest case files, case files from each provider dispatch and a survey among dispatched providers. The study was conducted in a rural district in Denmark. RESULTS: Home care providers were dispatched to 28 of the 60 OHCAs that occurred in the study period. In ten cases the providers arrived before the ambulance service and subsequently performed CPR. AED analysis was executed in three cases and shock was delivered in one case. For 26 of the 28 cases, the cardiac arrest occurred in a private home. Ninety-five per cent of the providers who had been dispatched to a cardiac arrest reported feeling prepared for managing the initial resuscitation, including use of AED. CONCLUSION: Home care providers are suited to act as first-responders in predominantly rural and residential districts. Future follow-up will allow further evaluation of home care provider arrivals and patient survival.

Effective risk stratification in patients with moderate cardiovascular risk using albuminuria and atherosclerotic plaques in the carotid arteries.

OBJECTIVES: The aim of this study was to investigate whether subclinical vascular damage improved traditional risk prediction, reclassifying individuals with regard to primary prevention. METHODS: Two thousand and fifty-nine healthy individuals aged 41, 51, 61, and 71 years were divided into age, Systematic COronary Risk Evaluation (SCORE), and Framingham risk score (FRS) groups. Subclinical vascular damage was defined as carotid-femoral pulse wave velocity at least 12 m/s, and carotid atherosclerotic plaques or urine albumin/creatinine ratio (UACR) at least 90th percentile of 0.73/1.06 mg/mmol in men/women. The composite endpoint of cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, and hospitalization for ischemic heart disease was recorded (n = 229). RESULTS: Both elevated UACR (P = 0.002) and atherosclerotic plaques (P < 0.0001) identified a subgroup of moderate SCORE risk patients and high-intermediate FRS risk patients with high risk (P = 0.04 and P = 0.001, respectively), whereas elevated carotid-femoral pulse wave velocity did not. Elevated UACR or presence of atherosclerotic plaques reclassified patients from moderate to high SCORE risk [net reclassification improvement of 6.4%; P = 0.025), or from high intermediate to high FRS risk (net reclassification improvement 8.8%; P = 0.002). Assuming primary prevention could reduce the relative cardiovascular risk by 24-27%, on the basis of actual levels of blood pressure and cholesterol, one composite endpoint could be avoided by giving primary prevention to 19 or 24 reclassified patients found by screening 52 or 104 patients with high-intermediate FRS or moderate SCORE risk, respectively. CONCLUSION: Elevated UACR and presence of atherosclerotic plaques could in a potentially cost-effective manner identify patients with moderate SCORE risk or high-intermediate FRS with actual high cardiovascular risk who will benefit from primary prevention.

Predicting retention time in hydrophilic interaction liquid chromatography mass spectrometry and its use for peak annotation in metabolomics.

Liquid chromatography coupled to mass spectrometry (LCMS) is widely used in metabolomics due to its sensitivity, reproducibility, speed and versatility. Metabolites are detected as peaks which are characterised by mass-over-charge ratio (m/z) and retention time (rt), and one of the most critical but also the most challenging tasks in metabolomics is to annotate the large number of peaks detected in biological samples. Accurate m/z measurements enable the prediction of molecular formulae which provide clues to the chemical identity of peaks, but often a number of metabolites have identical molecular formulae. Chromatographic behaviour, reflecting the physicochemical properties of metabolites, should also provide structural information. However, the variation in rt between analytical runs, and the complicating factors underlying the observed time shifts, make the use of such information for peak annotation a non-trivial task. To this end, we conducted Quantitative Structure-Retention Relationship (QSRR) modelling between the calculated molecular descriptors (MDs) and the experimental retention times (rts) of 93 authentic compounds analysed using hydrophilic interaction liquid chromatography (HILIC) coupled to high resolution MS. A predictive QSRR model based on Random Forests algorithm outperformed a Multiple Linear Regression based model, and achieved a high correlation between predicted rts and experimental rts (Pearson's correlation coefficient = 0.97), with mean and median absolute error of 0.52 min and 0.34 min (corresponding to 5.1 and 3.2 % error), respectively. We demonstrate that rt prediction with the precision achieved enables the systematic utilisation of rts for annotating unknown peaks detected in a metabolomics study. The application of the QSRR model with the strategy we outlined enhanced the peak annotation process by reducing the number of false positives resulting from database queries by matching accurate mass alone, and enriching the reference library. The predicted rts were validated using either authentic compounds or ion fragmentation patterns.

Transcript profiling of fructan biosynthetic pathway genes reveals association of a specific fructosyltransferase isoform with the high sugar trait in Lolium perenne.

Lolium perenne cultivars with elevated levels of fructans in leaf blades (high sugar-content grasses) have been developed to improve animal nutrition and reduce adverse environmental impacts of pastoral agricultural systems. Expression of the high sugar trait can vary substantially depending on genotype×environment (G×E) interactions. We grew three potential high sugar-content and a control cultivar in three temperature regimes and quantified water soluble carbohydrates (WSCs) and the expression of all functionally characterised L. perenne fructan pathway genes in leaf tissues. We also analysed the distribution, expression and sequence variation of two specific isoforms of Lp6G-FFT (fructan: fructan 6G-fructosyltransferase). Our study confirmed a significant G×E interaction affecting the accumulation of fructans in the high sugar-content cultivar AberDart, which accumulated higher levels of high DP (degree of polymerisation) fructans in blades compared to the control cultivar only when grown at 20°C (day)/10°C (night) temperatures. The cultivar Expo on the other hand accumulated significantly higher levels of high DP fructans in blades independent of temperature. Fructan levels in pseudostems were higher than in blades, and they increased markedly with decreasing temperature, but there was no consistent effect of cultivar in this tissue. The expression of the high sugar trait was generally positively correlated with transcript levels of fructosyltransferases. Presence and expression of only one of the two known 6G-FFT isoforms was positively correlated with high fructan biosynthesis, while the second isoform was associated with low fructan concentrations and positively correlated with fructan exohydrolase gene expression. The presence of distinct 6G-FFT sequence variants appears to be associated with the capacity of high sugar-content grasses to accumulate higher fructan levels particularly at warmer temperatures. These findings might be exploited for the selection and breeding of 'warm-effective' high sugar-content grasses to overcome some of the limitations of current high sugar-content ryegrass cultivars.

Analysis of low molecular weight metabolites in tea using mass spectrometry-based analytical methods.

Tea is the second most consumed beverage in the world after water and there are numerous reported health benefits as a result of consuming tea, such as reducing the risk of cardiovascular disease and many types of cancer. Thus, there is much interest in the chemical composition of teas, for example; defining components responsible for contributing to reported health benefits; defining quality characteristics such as product flavor; and monitoring for pesticide residues to comply with food safety import/export requirements. Covered in this review are some of the latest developments in mass spectrometry-based analytical techniques for measuring and characterizing low molecular weight components of tea, in particular primary and secondary metabolites. The methodology; more specifically the chromatography and detection mechanisms used in both targeted and non-targeted studies, and their main advantages and disadvantages are discussed. Finally, we comment on the latest techniques that are likely to have significant benefit to analysts in the future, not merely in the area of tea research, but in the analytical chemistry of low molecular weight compounds in general.

Non-targeted analysis by LC-MS of major metabolite changes during the oolong tea manufacturing in New Zealand.

Oolong tea is a semi-fermented tea that is partially oxidised during the manufacturing process to create a product unique in composition. In this study, we investigated the potential of non-targeted LC-MS with two complementary chromatographic modes to provide a "comprehensive and unbiased" view of biochemical compositional changes occurring during oolong tea manufacturing in New Zealand. Tea leaf samples from throughout the manufacturing/fermentation process during three different harvest periods (spring, summer and autumn) were analysed by four different LC-MS streams. Principal component analysis revealed the de-greening stage of the manufacturing process was responsible for major changes in the biochemical profile, with the methodology detecting changes in a wide range of metabolites of differing polarities, such as flavonoids, nucleosides and primeverosides. Changes during the fermentation phase of the manufacturing process were less marked, however significant increases in levels of free amino acids, a hydroxyjasmonic acid and related metabolites were observed.

Metabolite analysis of the effects of elevated CO2 and nitrogen fertilization on the association between tall fescue (Schedonorus arundinaceus) and its fungal symbiont Neotyphodium coenophialum.

Atmospheric CO2 is expected to increase to between 550 ppm and 1000 ppm in the next century. CO2-induced changes in plant physiology can have ecosystem-wide implications and may alter plant-plant, plant-herbivore and plant-symbiont interactions. We examined the effects of three concentrations of CO2 (390, 800 and 1000 ppm) and two concentrations of nitrogen fertilizer (0.004 g N/week versus 0.2 g N/week) on the physiological response of Neotyphodium fungal endophyte-infected and uninfected tall fescue plants. We used quantitative PCR to estimate the concentration of endophyte under altered CO2 and N conditions. We found that elevated CO2 increased the concentration of water-soluble carbohydrates and decreased the concentration of plant total amino acids in plants. Fungal-derived alkaloids decreased in response to elevated CO2 and increased in response to nitrogen fertilization. Endophyte concentration (expressed as the number of copies of an endophyte-specific gene per total genomic DNA) increased under elevated CO2 and nitrogen fertilization. The correlation between endophyte concentration and alkaloid production observed at ambient conditions was not observed under elevated CO2. These results suggest that nutrient exchange dynamics important for maintaining the symbiotic relationship between fungal endophytes and their grass hosts may be altered by changes in environmental variables such as CO2 and nitrogen fertilization.