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Upon dietary exposure, the endogenous metabolism responds to the diet-derived nutrients and bioactive compounds, such as phytochemicals. However, the responses vary remarkably due to the interplay with other dietary components, lifestyle exposures, and intrinsic factors, which lead to differences in endogenous regulatory metabolism. These physiological processes are evidenced as a signature profile composed of various metabolites constituting metabolic phenotypes, or metabotypes. The metabolic profiling of biological samples following dietary intake hence would provide information about diet-that is, as the intake biomarkers and the ongoing physiological reactions triggered by this intake-thereby enable evaluation of the metabolic basis required to distinguish the different metabotypes. The capacity of nontargeted metabolomics to also encompass the unprecedented metabolite species has enabled the profiling of multiple metabolites and the corresponding metabotypes with a single analysis, decoding the complex interplay between diet, other relevant factors, and health. In this systematic review, we screened 345 articles published in English in January 2007-July 2018, which applied the metabolomics approach to profile the changes of endogenous metabolites in the blood related to dietary interventions, either derived by metabolism of gut microbiota or the human host. We excluded all the compounds that were directly derived from diet, and also the dietary interventions focusing on supplementation with individual compounds. After the removal of less relevant studies and assessment of eligibility, 49 articles were included in this review. First, we mention the contribution of individual factors, either modifiable or nonmodifiable factors, in shaping metabolic profile. Then, how different aspects of the diet would affect the metabolic profiles are disentangled. Next, the classes of endogenous metabolites altered following included dietary interventions are listed. We also discuss the current challenges in the field, along with future research opportunities.

Background: The reported effects of flavanol-rich foods such as cocoa, dark chocolate, and apples on blood pressure and endothelial function may be due to the monomeric flavanols [mainly (–)-epicatechin (EC)], the oligomeric flavanols [procyanidins (PCs)], or other components. Reports of well-controlled intervention studies that test the effects of isolated oligomeric flavanols on biomarkers of cardiovascular health are lacking. Objective: We studied the acute and chronic effects of an EC-rich apple flavanol extract and isolated apple PCs on systolic blood pressure (BP) and other cardiometabolic biomarkers. Design: Forty-two healthy men and women with moderately elevated BP completed this randomized, double-blind, placebo-controlled, 4-arm crossover trial. Participants ingested a single dose of an apple flavanol extract (70 mg monomeric flavanols, 65 mg PCs), a double dose of this extract (140 mg monomeric flavanols, 130 mg PCs), an apple PC extract (130 mg PCs, 6.5 mg monomeric flavanols), or placebo capsules once daily for 4 wk, in random order. Biomarkers of cardiovascular disease risk and vascular function were measured before and 2 h after ingestion of the first dose and after the 4-wk intervention. Results: Compared with placebo, none of the isolated flavanol treatments significantly (P < 0.05) changed systolic or diastolic BP (peripheral and aortic), plasma nitric oxide (NO) reaction products, or measures of arterial stiffness (carotid femoral pulse-wave velocity, brachial-ankle pulse-wave velocity, or Augmentation Index) after 2 h or 4 wk of the intervention. There were no changes in plasma endogenous metabolite profiles or circulating NO; endothelin 1; total, HDL, or LDL cholesterol; triglycerides; fasting glucose; fructosamine; or insulin after 4 wk of the intervention. Conclusions: Our data suggest that, in isolation, neither monomeric flavanols nor PCs affect BP, blood lipid profiles, endothelial function, or glucose control in individuals with moderately elevated BP. The reported benefits of consuming flavanol-rich cocoa, chocolate, and apple products appear to be dependent on other components, which may work in combination with monomeric flavanols and PCs. This trial was registered at www.clinicaltrials.gov as NCT02013856.

Escherichia coli is a model organism that has been exploited to reveal key details of hydrogen peroxide stress: the biomolecules that H(2)O(2) most rapidly damages and the defensive tactics that organisms use to fend it off. Much less clear is the amount of exogenous H(2)O(2) that is sufficient to injure the bacterium and/or to trigger its stress response. To fill this gap, we need to study the behavior of cells when they are exposed to defined amounts of H(2)O(2) on an hours-long time scale. Such experiments are difficult because bacteria rapidly consume H(2)O(2) that is added to test cultures. Further, lab media itself can generate H(2)O(2), and media components interfere with the quantification of H(2)O(2) levels. In this study we describe mechanisms by which media components interfere with H(2)O(2) determinations, and we identify simple ways to minimize and correct for this interference. Using these techniques, it was shown that standard media generate so much H(2)O(2) that most intracellular H(2)O(2) derives from the medium rather than from endogenous metabolism. Indeed, bacteria spread on plates must induce their stress response or else perish. Finally, two straightforward methods were used to sustain low-micromolar steady-state concentrations of H(2)O(2). In this way we determined that > 2 μM extracellular H(2)O(2) is sufficient to trigger the intracellular OxyR stress response, and > 5 μM begins to impair cell growth in a minimal medium. These concentrations are orders of magnitude lower than the doses that have typically been used in lab experiments. The new approaches should enable workers to study how various organisms cope with natural levels of H(2)O(2) stress.

A systematic experimental study of the effect of hydraulic residence time (HRT) and solids residence time (SRT) on conventional suspended-growth biological wastewater treatment processes was carried out. The aim of this study was to identify the conditions that minimise the reactor volume, i.e. maximise the organic load rate (OLR), and minimise the oxygen consumption. Lab-scale sequencing batch reactors (SBRs) were operated with glucose or ethanol as only carbon sources, with HRT in the range 0.25–4 day and SRT in the range 1–71 day. The highest OLR values which gave satisfactory performance were 4.28 and 4.14 gCOD/l.day for glucose and ethanol, respectively, which are among the highest reported for conventional aerobic suspended-growth processes. The highest OLR values were obtained with HRT = 0.25 day, SRT = 3.1 day for glucose and HRT = 0.5 day, SRT = 4.9 day for ethanol. The minimum oxygen consumption was 0.36 and 0.69 kg O2/kg COD removed for glucose and ethanol, respectively. In disagreement with conventional theories, it was found that biomass production also depended on the OLR as well as on the SRT, higher OLRs giving lower biomass production for the same SRT. From the kinetic analysis of the experimental data, this behaviour, which has important consequences for the design of biological wastewater treatment processes, was explained with a higher rate of endogenous metabolism at higher OLRs.

This paper investigates whether it is possible to calculate the periodic steady state of sequencing batch reactors (SBRs) using kinetic parameters obtained from batch tests. Two industrial wastewaters were treated in SBRs with measurement of the substrate removal and biomass production. Three batch tests at different initial substrate to biomass ratios (S0/X0) were carried out on each wastewater, with measurement of the oxygen uptake rate (OUR). The OUR profiles were used for the estimation of the kinetic parameters using a mathematical model consisting of substrate hydrolysis, biomass growth and endogenous metabolism. The estimated kinetic parameters were then used to calculate the substrate and biomass concentration at the periodic steady state of the SBRs and the obtained values were compared with the experimental data from the SBR runs. It was not possible for one set of kinetic parameters to describe different tests, even for the same wastewater. However, when each test was fitted individually, the model gave good description of the OUR profiles. When used to calculate the periodic steady state of the SBR, the estimated parameter values gave in all cases a complete or almost complete COD removal, in agreement with what observed in the SBR, but satisfactory predictions of biomass concentration for both wastewaters were only obtained with the parameters estimated in the low S0/X0 tests (highest discrepancy 37%).

Food-derived compounds have been linked with decreased risk of developing chronic health conditions. The interest in the development of functional biopeptides from food proteins can be attributed to increasing consumer demand for safe health-promoting agents. The meat proteome, although not as widely investigated as dairy, fish or plant proteins, contains peptide sequences with a variety of beneficial health effects particularly antihypertensive property as well as other health-promoting functions such as antioxidant, antithrombotic, anticancer, immunomodulatory and antimicrobial activities. Despite the prospects, current literature indicates dearth of extensive information on validation of the physiological functions of meat-derived biopeptides in animal models and human subjects. Moreover, bioinformatic analysis has indicated the possibility of generating a myriad of biopeptides during endogenous metabolism of dietary meat proteins, and through the use of food-grade exogenous proteases. Consequently, there is a strong need to explore the meat proteome as precursor of functional biopeptides for the development of commercial functional foods and nutraceuticals.

Measurements of historical specimens are widely applied in studies of taxonomy, systematics, and ecology, but biologists often assume that the effects of preservative chemicals on the morphology of amphibian specimens are minimal in their analyses. We compared the body length and body mass of 182 samples of 13 live and preserved (up to 10 years) anuran species and found that the body length and body mass of preserved specimens significantly decreased by 6.1% and 24.8%, respectively, compared to those measurements of their live counterparts. The changes in body length and mass also exhibited highly significant variations between species. Similarly, there were significant differences in shrinkage of body length and body mass between sexes, where males showed greater shrinkage in body length and body mass compared to females. Preservation distorted the magnitude of the interspecific differences in body length observed in the fresh specimens. Overall, the reduction in body length or mass was greater in longer or heavier individuals. Due to the effects of preservation on amphibian morphology, we propose two parsimonious conversion equations to back-calculate the original body length and body mass of studied anurans for researchers working with historical data, since morphological data from preserved specimens may lead to incorrect biological interpretations when comparing to fresh specimens. Therefore, researchers should correct for errors due to preservation effects that may lead to the misinterpretation of results.

We read with great interest the recent report by Nigam et al. [(1)][1] about the AFFORD (Multi-Center Study to Evaluate the Effect of n-3 Fatty Acids [Omega-3] on Arrhythmia Recurrence in Atrial Fibrillation) trial. Supplementation of 4 capsules fish oil per day (containing a total of 1,600 mg

Xenobiotic exposure, especially high-dose or repeated exposure of xenobiotics, can elicit detrimental effects on biological systems through diverse mechanisms. Changes in metabolic systems, including formation of reactive metabolites and disruption of endogenous metabolism, are not only the common consequences of toxic xenobiotic exposure, but in many cases are the major causes behind development of xenobiotic-induced toxicities (XIT). Therefore, examining the metabolic events associated with XIT generates mechanistic insights into the initiation and progression of XIT, and provides guidance for prevention and treatment. Traditional bioanalytical platforms that target only a few suspected metabolites are capable of validating the expected outcomes of xenobiotic exposure. However, these approaches lack the capacity to define global changes and to identify unexpected events in the metabolic system. Recent developments in high-throughput metabolomics have dramatically expanded the scope and potential of metabolite analysis. Among all analytical techniques adopted for metabolomics, liquid chromatography-mass spectrometry (LC-MS) has been most widely used for metabolomic investigations of XIT due to its versatility and sensitivity in metabolite analysis. In this review, technical platform of LC-MS-based metabolomics, including experimental model, sample preparation, instrumentation, and data analysis, are discussed. Applications of LC-MS-based metabolomics in exploratory and hypothesis-driven investigations of XIT are illustrated by case studies of xenobiotic metabolism and endogenous metabolism associated with xenobiotic exposure.

Mono-ADP-ribosylation was originally discovered as the mechanism by which diphtheria toxin inactivates protein synthesis. It is now apparent that higher organisms use analogous mechanisms to regulate endogenous metabolism. Here, the relationship between bacterial toxins and vertebrate mono-ADP ribosyltransferases is explored.

Nearly 90% of vitamin C in the human diet is obtained from fruits and vegetables as ascorbic and dehydroascorbic acids. However, these compounds are sensitive to light and oxygen and may decompose under normal transport and storage conditions, resulting in reduction of the nutritional value of the foodstuffs. In this work, the effect of various commercial and domestic storage conditions (3, 8, 23°C with or without light) on vitamin C contents of some fruits and vegetables produced in Quebec was studied. In general, degradation of vitamin C is a function of time. In some foodstuffs, however, the onset of degradation is delayed during the first few days during which the vitamin content actually increases as a result of continuing endogenous metabolism.

An LKB-2277 Bioactivity Monitor was used to determine thermograms of the endogenous metabolism of E. coli. The experimental results indicate that the relation between cell concentration and power output can be characterized by the equations where P is the power output (μW), C is cell concentration (mg ml−1), P0 is the power output produced by the metabolism of a single cell (P0 = P C ), and k, a and K are constants which depend on the culture conditions and physiogenic state of the cells. The physical meaning of the group equation can be explained as follows: eqn. (1) indicates that the endogenous metabolic power and cell concentration conform to a linear relation; eqn. (2) is a zero order equation which indicates that P0 is independent of cell concentration, i.e. it is not inhibited by cell density. This is very different from the metabolism of resting cells.

Thermograms of growth metabolism, endogenous metabolism and non-growth metabolism of resting cells of E. coli were obtained using an LKB-2277 Bioactivity Monitor. From these thermograms it can be established that the thermokinetic equation for the growth metabolism of E. coli is d p /d t = k 1 p , with order of metabolism n = 1, k 1 = 0.03993 min −1 ( k 1 , multiplication rate constant; p , power output; t time). The corresponding thermokinetic equation for the non-growth metabolism of resting cells is d p /d t = 0, k o = 0. The equation for endogenous metabolism is dependent on the previous equation, but it can be divided into two parts: at an early phase, d p /d t = 0, k 0 = 0; at a later phase, d p /d t = k −1 p , n = 1, k −1 = −0.01769 min −1 . Thus, thermokinetic equations for the various different kinds of metabolism in cells (in this case, bacteria) can be obtained by microcalorimetric methods.

In view of the scarcity of data in the literature as to the value of various proteins for poultry feeding, experimental work on this phase of the problem was undertaken in this laboratory. It was planned first to study the endogenous nitrogen excretion of birds on a nitrogen-free diet to obtain a figure representative of their excretion in terms of milligrams of nitrogen excreted daily per kilogram of live weight. Preliminary trials with mature birds indicated that this figure would approach a constant value. The chickens were then to be placed on a ration containing a known amount of protein from a certain source and the total nitrogen of their excrement again determined. Then, the difference between the nitrogen excreted when a protein was included in the diet, and when on a nitrogen-free ration, divided by the amount of nitrogen fed per kilogram would be the unutilized portion. When this . . .

Osborne and Mende1, Johns and Finks2, Sure3, Jones and Murphy4, and others, have studied the need of the animal organism for cystine. As a result of their work cystine is generally recognized as being one of the essential amino acids. Jones, Gersdorff and Moeller5 tabulated the cystine content of various proteins. Lewis6–7 has shown “that the addition of cystine in small amounts to the food of dogs maintained on a low protein level diminished the loss of nitrogen from the body and favorably influenced the nitrogen balance.” He considered the effect of cystine to be specific. The writers8 found a marked increase in the endogenous loss of nitrogen of molting birds from the normal level of non-molting birds. They9 likewise found that cystine increased the extent to which casein is utilized by hens, as indicated, by the nitrogen retained by birds fed equal amounts of casein. The fact that . . .

In a previous article the writers (1) reported a preliminary study of the endogenous metabolism of hens and capons, and outlined a method of studying the utilization of various proteins by poultry. The purpose of the present investigation was to establish a figure representative of the average endogenous nitrogen excretion of mature Rhode Island Red hens. Such a figure might simplify the determination of the “biological·value” of proteins, by eliminating the necessity of a preliminary determination of the endogenous loss of nitrogen for each bird. Previous work (1) pointed to a decreasing nitrogen excretion per kg. of body weight as the hens grew older. Mitchell and Villegas (2) in working with rats noted a similar decrease in urinary nitrogen per 100 gms. of body weight, from one experimental period to another. They state “it has been our experience that rats kept for several weeks confined in our metabolism dishes show . . .

The purpose of this investigation was the determination of the variation of uric acid, creatinine and non-protein in the blood of chickens during the molting season. It was noted by Thompson and Carr 2 that polyneuritis developed in chickens in a much shorter period if they were molting. They also found that with the onset of polyneuritis there was a marked increase in the uric acid and creatinine content of the blood. These facts seemed to indicate a disturbance of the endogenous metabolism. Therefore it was thought since molting hastened polyneuritis it too was closely related to endogenous metabolism, and consequently the amount of non-protein, creatinine and uric acid should increase during the molting period when the birds are losing their feathers. Further, Blish and Ackerson 3 (1923) have observed that during the molting period the amount of nitrogen excreted is increased, which gives more evidence that molting produces a disturbance of . . .