Trimethylamine Oxide Levels Research Articles

Naochang Tongtiao acupuncture based on brain-gut axis for acute ischemic stroke and its effect on levels of IL-17, hs-CRP and TMAO

To compare the clinical therapeutic effect on acute ischemic stroke between Naochang Tongtiao acupuncture (acupuncture for brain-gut homology) and conventional acupuncture, and to explore the possible mechanism. A total of 64 patients with acute ischemic stroke were randomized into an observation group and a control group, 32 cases in each one. Basic western medical therapy was adopted in both groups. In the observation group, Naochang Tongtiao acupuncture was applied at anterior oblique line of vertex-temporal, Zhongwan (CV 12), Guanyuan (CV 4), Tianshu (ST 25), Zusanli (ST 36), Shangjuxu (ST 37) and Xiajuxu (ST 39). In the control group, conventional acupuncture was applied. The treatment was given once a day, 6 days a week for 3 weeks in both groups. Before and after treatment, National Institution of Health stroke scale (NIHSS) score, serum levels of interleukin-17 (IL-17) and hypersensitive C reactive protein (hs-CRP), and plasma level of trimethylamine oxide (TMAO) were compared in the two groups. After treatment, NIHSS scores, serum levels of IL-17 and hs-CRP, and plasma levels of TMAO were decreased compared before treatment in both groups (P<0.01), and those in the observation group were lower than the control group (P<0.05). Naochang Tongtiao acupuncture can improve the nerve function in patients with acute ischemic stroke, its therapeutic effect is superior to conventional acupuncture, the mechanism may relate to the regulation on inflammatory reaction and the level of intestinal flora metabolite.

Effect of the ethyl acetate extract of Sophora flavescens Aiton on diabetic retinopathy based on untargeted retinal metabolomics

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and a leading cause of vision impairment and blindness, which lacks effective diagnostic measures and therapeutic options. Sophora flavescens Aiton or “Kushen” is a traditional Chinese medicine used since ancient times, either alone or in combination, to clear heat, dampness, and tearing, and to treat ocular diseases and improve eyesight. Additionally, the flavonoids of Sophora flavescens Aiton extracted using ethyl acetate (EtOAc) (SFE) is effective in managing diabetes and diabetic vascular complications. In this study, we explored the pharmacodynamic effects and material basis of action of SFE on DR for the first time and elucidated the mechanism based on untargeted retinal metabolomics. Results from the pharmacodynamic studies showed that SFE could reduce blood glucose levels in rats, regulate serum lipopolysaccharide, tauroursodeoxycholic acid, and trimethylamine oxide levels, and significantly improve the structure of retina in rats with DR. Moreover, SFE could protect the blood-retinal barrier, reduce angiogenesis and capillary formation, and inhibit retinal nerve cell apoptosis. A total of 13 compounds were identified in the aqueous humor and retina, which were dihydroflavonoid, isoflavonoid, pterostane flavonoid, chalcone, and dihydroflavonol derivatives. In addition, 39 differential metabolites were screened based on retinal metabolomics data and 23 were found to be affected by SFE, indicating its anti-DR effect by regulating the synthetic metabolic pathways, including lactose, bile acid, glycerophospholipid, arginine, purine, and pyrimidine metabolism pathways. Collectively, our findings elucidated the effects, material basis, and treatment mechanism of SFE on DR systematically and could lay the foundation for promoting the clinical application of Sophora flavescens Aiton.

Molecular Identification and Selection of Probiotic Strains Able to Reduce the Serum TMAO Level in Mice Challenged with Choline.

Trimethylamine oxide (TMAO) originates from trimethylamine (TMA), which is oxidized in the liver by hepatic flavin-containing monooxygenases (FMO3). TMA is produced by its dietary precursors such as choline, carnitine, and phosphatidylcholine by gut microbiota. TMAO attracts attention, identified as a novel and independent risk factor for promoting obesity, atherosclerosis and cardiovascular disease (CVD), chronic kidney disease (CKD), insulin tolerance, and colon cancer. Probiotics have been considered as live microorganisms, providing benefits to their host when they are given in sufficient quantities and administered continuously. The objective of this study is to suggest a method to select potential probiotic strains to reduce the serum concentration of TMAO in mice fed with choline. In this work, we chose three lactobacilli with strong adherence capability, and fed multistrain formula (MF) to the mice challenged with choline. On days 7, 14, and day 28, it was found that the MF-containing L. amylovorus LAM1345, Lpb. plantarum LP1145, and Lim. fermentum LF33 showed a significant reduction in serum TMAO and TMA levels. For the single strains, LP1145 reduced TMAO on days 14 and 28, and strain LAM1345 reduced TMAO significantly on days 7 and day 14. For strain LF1143 from strain LF33, it showed no significant effect on TMAO and TMA. Thus, MF showed the best effect, which may be due to the additive and synergetic effect and the contribution of strain LP1145 and LAM1345. Finally, for the LAM1345 and LP1145 strains, we used molecular identification and typing methods to assure that these two strains are unique strains. The methods used for LAM 1345 were leader peptidase A (lepA) gene analysis and phylogenetic analysis, while for strain LP 1145and other strains of Lpb. plantarum subsp. plantarum sequences were compared using the whole-genome multilocus sequence typing (wgMLST) method.

Trimethylamine oxide and its possible role in the development and progression of cardiovascular disease

Cardiovascular diseases continue to be the leading cause of death throughout the world and in Russia. Therefore, new possible risk factors for their development and progression are being studied. To date, information have been accumulated on unfavorable prognostic effect of elevated trimethylamine oxide (TMAO) levels on cardiovascular events, and the possible role of phospholipids (PLs) is being discussed. The aim of this review was to analyze the literature data on the potential relationship of TMAO and PLs with cardiovascular risk (CVR), as well as possible solutions to this problem. The search and analysis of publications was performed using Elibrary, PubMed, Medline, and Google Scholar databases in the period from their creation to 2021. It was found that high TMAO concentrations can have pro-inflammatory effects, stimulate atherogenesis and increase platelet aggregation. An increase in the blood TMAO levels increases the risk of cardiovascular events in patients with coronary artery disease, is associated with an increased risk of cardiovascular and all-cause death in patients with peripheral arterial disease and heart failure, and correlates with the extent of brain regions involved in stroke. The most important part in TMAO formation is taken by the gut microbiota, which metabolizes substrates, including PLs, to trimethylamine, which, when absorbed, is converted into TMAO in the liver. The analysis of available studies shows that the excessive intake of PLs into the gastrointestinal tract and the increased TMAO production are potentially interrelated with an increase in CVR. At the same time, PLs are currently used as drugs, in particular, as hepatoprotective agents. In view of this, large-scale randomized clinical trials are needed to study the CVR profile in patients receiving such therapy. Currently, other hepatoprotective agents are available that are devoid of such potential risks, since they do not contain PLs. One of these agents is ursodeoxycholic acid, which has proven its effectiveness and safety, including in patients with high CVR in routine clinical practice.

Anthocyanins from purple sweet potato alleviate doxorubicin‐induced cardiotoxicity in vitro and in vivo

In this study, anthocyanins were extracted and purified from purple sweet potato anthocyanins (PSPA) and the alleviative effect of PSPA on doxorubicin (DOX)-induced cardiotoxicity was investigated. High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) results showed that 10 kinds of substances were identified in PSPA and the PSPA was mainly composed of cyanidin (62.9%) and peonidin (21.46%). In in vitro experiments, PSPA reduced the excessive release of inflammatory factors (NO and TNF-α) induced by DOX and decreased the secretion of trimethylamine oxide (TMAO), lactic dehydrogenase (LDH), and creatine kinase (CK) caused by myocardial injury. In in vivo experiments, PSPA inhibited the release of NO and MDA levels in heart tissue. Meanwhile, mice treated with PSPA decreased the levels of LDH, CK, TNF-α, and TMAO in serum and heart tissue when compared with the DOX group. In addition, the histopathological results of the heart tissue also showed a protective effect of PSPA on the pathological changes in heart. These results provide a reference for the application of PSPA as a functional food to intervene in DOX-induced cardiotoxicity. PRACTICAL APPLICATIONS: The effects of anthocyanins from purple sweet potato anthocyanins (PSPA) on doxorubicin (DOX)-induced cardiotoxicity were investigated in vitro and in vivo. The results indicated that PSPA could significantly ameliorate DOX-induced heart failure. The obtained results could provide the potential application of PSPA as an alternative therapy for cardiotoxicity caused by DOX in the functional food industry.

Long-lasting effects of postweaning sodium butyrate exposure on social behaviors in adult mice

BackgroundThe function of gut microbiota as its role in normal physiology and involvement in brain function has gained a great deal of attention. The potential long-lasting effects of postweaning sodium butyrate (SB) exposure on social behaviors are still unknown; however it acts as one of the metabolites of gut microbiota. MethodsMale mice (24-day old) were exposed to SB through drinking water for 21 continuous days. A series of behavioral tests, mainly including bedding preference test (BP), sexual preference test (SP), social interaction test (SI), tube dominance test (SDT), forced swimming test (FST), open field test (OFT), novel object recognition task (NOR) were conducted at different time after 21-d SB exposure. Serum Trimethylamine oxide (TMAO) levels were investigated to gain insight into a potential mechanism. ResultsBehavioral results indicated that postweaning SB exposure significantly decreased the social dominance status of low-ranked mice and decreased the sexual preference without affecting social interaction. SB exposure also exerted transient anxiolytic-like effects, while having induced a long-lasting depression-like effect without effects on memory formation. Postweaning SB exposure increased serum TMAO levels in mice, especially in lower-ranked mice, but decreased in higher-ranked mice. LimitationsLack of understanding of the underlying mechanism. ConclusionsThese findings provide direct evidence, for the first time, that postweaning SB exposure produces long-term effects on social behaviors in adult mice, mainly referring to sexual orientation, social dominance, and depression-like behaviors, which may be related to the serum TMAO levels, highlighting the long-lasting potential effects of gut-brain interaction on social behaviors.

Reduction of intestinal trimethylamine by probiotics ameliorated lipid metabolic disorders associated with atherosclerosis.

The purpose of this study was to explore the effect of trimethylamine (TMA)-degrading probiotic agents on trimethylamine oxide (TMAO) and the related lipid metabolism in mice. Ten lipid-lowering strains were detected with TMA-degradation capacity in vitro. After probiotic intervention for the mice on a high-choline diet, TMA content in cecum and TMA and TMAO in serum was explored, as well as the expression of key gene flavin-containing monooxygenase 3 (FMO3) of the TMA-TMAO metabolism. The expression of genes related to the lipid metabolism was also investigated by real-time polymerase chain reaction and Western blot. Finally, the colonization of functional strains in the intestine were examined. Five of 10 lipid-lowering strains effectively degraded TMA in vitro, and the TMA level in the cecum of mice were reduced after probiotic intervention. TMA level and TMAO in serum were also significantly reduced by the strains (P < 0.05), but not due to the regulation of FMO3. Probiotic agents could improve the lipid metabolism by acting on the Farnesoid X receptor and cholesterol 7-alpha hydroxy-lase. Among the strains, Bifidobacterium animalis subsp. lactis F1-3-2 showed the most prominent performance and colonized in the cecum of mice. Bif. animalis subsp. lactis F1-3-2 could be colonized in the cecum, and might directly degrade TMA or change the structure of intestinal flora. The strain had an effect on TMA and TMAO levels in vivo by decreasing cecum TMA. The strain was demonstrated to participate in the TMA-TMAO regulation, improve the lipid metabolism, and alleviate atherosclerosis caused by TMAO. However, FMO3 had not changed in this process, and needs further study.

Fermentation of Resistant Starch Is Not a Predictor of Very High or Low Serum TMAO in Rats, but Results in Greater Serum TMAO than Controls

Abstract Objectives Consumption of resistant starch (RS) has positive gut health benefits, but RS has been associated with increased serum trimethylamine oxide (TMAO). Increased serum TMAO has been linked to enhanced risk of cardiovascular death. A human study found that RS and a high fat (41% of energy) diet resulted in higher TMAO levels compared to a low RS diet, but this was not seen in a high carbohydrate diet (27% energy as fat). We wanted to ascertain serum TMAO in rats fed a high-RS diet with moderate (MF) or high fat (HF) diets compared to controls. Methods Twenty-four male, Sprague-Dawley rats (n = 6) were fed either 23% RS type 2, high-amylose diet or a control diet using 100% amylopectin with either MF (30% energy) or HF (42% energy) levels. A 2X choline amount had been used in the AIN-93M diets as substrate for ultimate production of TMAO. After six weeks, serum TMAO was measured using stable isotope dilution liquid chromatography tandem mass spectrometry. Data were analyzed as a 2 × 2 factorial followed by Tukey test (P &amp;lt; 0.05). Serum TMAO is assessed for risk of death over a seven-year period into quadrants. Quadrants 3 (4.28–7.89 µM) and 4 (7.91-186.1 µM) have greater risk. Quadrants 1 (0.12–2.55 µM) and 2 (2.56–4.27 µM) had much lower risk. Results Average TMAO level for rats fed RS HF was 2.94 ± 0.4, and RS MF was 2.42 ± 0.4. The control HF was 1.53 ± 0.17, and control MF was 1.06 ± 0.17. Rats fed RS had significantly greater TMAO levels of 2.68 ± 0.28, quadrant 2, while the control rats had an average of 1.3 ± 0.12, quadrant 1. There was no significant increased effect for MF vs. HF. However, the variability was similar for the two RS groups with values in quadrants 1–3. Amount of fermentation was not associated with TMAO amounts. For example, the RS rat with the lowest serum TMAO (0.87 µM) had an empty cecum weight (ECW) of 2.40 g, while the highest (4.41 µM) had an ECW of 2.29 g. Conclusions Sprague-Dawley rats fed either MF or HF had increased TMAO with consumption of RS. Data indicate amount of fermentation is not the reason for increased TMAO. Possible differences in gut bacteria that produce trimethylamine from choline may be cause of TMAO production in the rats. Funding Sources LSU AgCenter and Lerner Research Institute (Dr Stan Hazen) of Cleveland Clinic for analysis of serum TMAO, and starches were gifted from Ingredion Incorporated.

Plasma from some patients with amyotrophic lateral sclerosis exhibits elevated formaldehyde levels

IntroductionThe aim of this study was to determine whether patients with amyotrophic lateral sclerosis (ALS) exhibit higher plasma levels of formaldehyde (FA) than controls, and to look for alterations in levels of FA precursors. MethodsWe studied 40 heathy controls and 50 ALS patients from the Motor Neuron Disease clinic at the Royal Brisbane & Women's Hospital. Plasma FA levels were quantified using a FA detection assay. Trimethylamine (TMA) and trimethylamine oxide (TMAO) in plasma were quantified by multiple reaction monitoring (MRM) mass spectrometry. Plasma levels in patients and controls were compared using Mann-Whitney U test and Spearman's correlation test was used to assess the correlation between levels of FA, TMA, TMAO and other variables. ResultsThe levels of plasma FA were significantly greater in ALS subjects than controls. TMA and TMAO levels were not significantly different between healthy controls and patients, but were greater in ALS subjects with elevated FA levels than those with normal levels. Of note, levels of TMA and TMAO demonstrated a significant positive correlation with plasma FA levels (spearman's correlation coefficients of TMA with FA [r = 0.451, p = 0.010] and TMAO [r = 0.401, p = 0.023]). There was no association of FA levels with disability measured with the ALS functional rating scale, with the duration of disease or with the age of the subjects. ConclusionElevated FA is found in some patients with ALS. FA is neurotoxic and could contribute to disease pathogenesis.

Trimethylamine But Not Trimethylamine Oxide Increases With Age in Rat Plasma and Affects Smooth Muscle Cells Viability

It has been suggested that trimethylamine oxide (TMAO), a liver oxygenation product of gut bacteria-produced trimethylamine (TMA), is a marker of cardiovascular risk. However, mechanisms of the increase and biological effects of TMAO are obscure. Furthermore, the potential role of TMAO precursor, that is TMA, has not been investigated. We evaluated the effect of age, a cardiovascular risk factor, on plasma levels of TMA and TMAO, gut bacteria composition, gut-to-blood penetration of TMA, histological and hemodynamic parameters in 3-month-old and 18-month-old, male, Sprague-Dawley and Wistar-Kyoto rats. Cytotoxicity of TMA and TMAO was studied in human vascular smooth muscle cells. Older rats showed significantly different gut bacteria composition, a significantly higher gut-to-blood TMA penetration, and morphological and hemodynamic alterations in intestines. In vitro, TMA at concentration of 500 µmol/L (2-fold higher than in portal blood) decreased human vascular smooth muscle cells viability. In contrast, TMAO at 1,000-fold higher concentration than physiological one had no effect on human vascular smooth muscle cells viability. In conclusion, older rats show higher plasma level of TMA due to a "leaky gut". TMA but not TMAO affects human vascular smooth muscle cells viability. We propose that TMA but not TMAO may be a marker and mediator of cardiovascular risk.

Foreword

The extensive collection of bacteria cohabiting within the host collaborates with human functions and metabolisms in both health and disease. The fine equilibrium of commensals is tightly controlled and an imbalance (“dysbiosis”) in the gut microbiota can play different roles in human disease. The development of new genome sequencing techniques has allowed a better understanding of the role of human gut microbiota. This led to the identification of numerous metabolites produced in the gut, which have been suggested to play a role in human disease. Among these, trimethylamine oxide (TMAO) appears to be of particular importance as a risk factor and potentially as a causative agent of various pathologies, most remarkably cardiovascular and disease and other associated conditions. Mechanistic links are yet to be established, however, increased levels of TMAO have been shown to augment the risk of developing renal failure, metabolic syndrome, diabetes mellitus, heart failure, hypertension, atherosclerosis, and dyslipidemia ultimately leading to increased risk of serious cardiovascular events. This article reviews the potential impact of TMAO in human cardiovascular disease.

Lactobacillus rhamnosus GG strain mitigated the development of obstructive sleep apnea-induced hypertension in a high salt diet via regulating TMAO level and CD4+ T cell induced-type I inflammation

Obstructive sleep apnea (OSA) and high salt content in modern diet has been particularly implicated in systemic hypertension, leading to increased morbidity and mortality. Gut dysbiosis, associated with increased risk of systemic immunological imbalance, plays a causal role in the development of cardiovascular diseases. Here, we investigated the effect of Lactobacillus rhamnosus GG strain (LGG) on the development of hypertension induced by OSA and high salt diet. In this study, hypertension was modeled in rats by feeding a high salt diet (HSD) for 6 wk and exposuring to chronic intermittent hypoxia (CIH) during the sleep cycle. We found that OSA combined with HSD increased the severity of hypertension through increasing level of blood Trimethylamine-Oxide (TMAO), release of Th1-related cytokine (IFN-γ) and inhibition of anti-inflammatory cytokine (TGF-β1), and affected the gut microbiome in rats, particularly by depleting Lactobacillus. In addition, expression of PERK1/2, PAkt and PmTOR increased in the aorta from rats with a CIH exposure and HSD. Consequently, treatment of model rats with LGG prevented aggravation of hypertension by reducing blood TMAO levels, modulating Th1/Th2 cytokine imbalance and suppressing phosphorylation levels of ERK1/2, Akt and mTOR. In line with these findings, our results connect high salt diet to the gut–immune axis and highlight the gut microbiome as a potential therapeutic target to counteract the development of OSA-induced hypertension basing on a high salt diet.

Sanhuang Xiexin decoction promotes good functional outcome in acute ischemic stroke.

ObjectivesTo explore the efficiency and safety of Sanhuang Xiexin decoction in the treatment of acute ischemic stroke (AIS) patients after endovascular intervention examination.MethodsIn this prospective observational study, 121 AIS patients admitted in our hospital were enrolled from January 2012 to December 2015. They were randomly divided into two groups, 61 patients received Sanhuang Xiexin decoction + basic treatment (SX group) and 60 patients received basic treatment (control group). The prescription of Sanhuang Xiexin decoction was taken in the SX group, with one dose (100 ml), twice a day for 7 days orally. For all patients, blood samples were drawn on the first morning and sixth morning after endovascular intervention examination under fasting state for Fib (fibrinogen), PAgT (platelet aggregation test), CRP (C‐reactive protein), and TMAO (trimethylamine oxide) tested. Estimate the changes in plasma Fib, PAgT, CRP, and TMAO levels and the syndrome of fire‐heat scores.ResultsThe plasma Fib, PAgT, CRP, and TMAO levels in the SX group were significantly lower than those in the control group (PFib < 0.01, PPAgT < 0.01, PCRP = 0.02, PTMAO < 0.01). The syndrome of fire‐heat scores in the SX group was significantly lower than that in the control group (p < 0.01). The incidences of ischemic cerebrovascular events within 3 and 6 months after endovascular intervention treatment in the SX group were lower than those in the control group (P3 month = 0.04, P6month = 0.03).ConclusionsThe prescription of Sanhuang Xiexin is efficient and safe in the treatment of AIS patients after endovascular intervention examination through reducing the inflammatory factors.

Synthetic capacity does not predict elasmobranchs' ability to maintain trimethylamine oxide without a dietary contribution

Trimethylamine oxide (TMAO) is an organic osmolyte and universal protein stabilizer. Its role as a cytoprotectant is particularly important in ureosmotic elasmobranchs that accumulate high levels of urea, a macromolecular perturbant. Feeding is a key component in the turnover and maintenance of these nitrogenous compounds. However, previous studies examining TMAO regulation have been largely completed using starved individuals, when nitrogen balance is altered. Here, under fed conditions, we test the importance of dietary TMAO on long-term maintenance in three elasmobranch species with differing endogenous synthetic capacities. Smoothhounds (Mustelus canis), spiny dogfish (Squalus acanthias), and little skates (Leucoraja erinacea) exhibited species- and tissue-specific differences in their ability to conserve TMAO when fed a low TMAO diet for 56days. Smoothhounds, a species with the capacity for endogenous production, exhibited a decrease in muscle TMAO. Spiny dogfish and little skates, species with no reported ability for synthesis, exhibited decreases in plasma and liver TMAO, respectively. Our findings are contrary to previous starvation studies demonstrating constant levels of TMAO for up to 56days in elasmobranchs. Further, the previously reported synthetic capacity of these species did not correlate with their ability to conserve TMAO and cannot be used to predict a species reliance on dietary contributions for prolonged maintenance. It is possible that all species rely to a degree on absorption of TMAO from the diet or that alternate synthetic or regulatory pathways play a larger role than previously thought.

Kt/Vurea and Nonurea Small Solute Levels in the Hemodialysis Study.

The Hemodialysis (HEMO) Study showed that high-dose hemodialysis providing a single-pool Kt/Vurea of 1.71 provided no benefit over a standard treatment providing a single-pool Kt/Vurea of 1.32. Here, we assessed whether the high-dose treatment used lowered plasma levels of small uremic solutes other than urea. Measurements made ≥3 months after randomization in 1281 patients in the HEMO Study showed a range in the effect of high-dose treatment compared with that of standard treatment: from no reduction in the level of p-cresol sulfate or asymmetric dimethylarginine to significant reductions in the levels of trimethylamine oxide (-9%; 95% confidence interval [95% CI], -2% to -15%), indoxyl sulfate (-11%; 95% CI, -6% to -15%), and methylguanidine (-22%; 95% CI, -18% to -27%). Levels of three other small solutes also decreased slightly; the level of urea decreased 9%. All-cause mortality did not significantly relate to the level of any of the solutes measured. Modeling indicated that the intermittency of treatment along with the presence of nondialytic clearance and/or increased solute production accounted for the limited reduction in solute levels with the higher Kt/Vurea In conclusion, failure to achieve greater reductions in solute levels may explain the failure of high Kt/Vurea treatment to improve outcomes in the HEMO Study. Furthermore, levels of the nonurea solutes varied widely among patients in the HEMO Study, and achieved Kt/Vurea accounted for very little of this variation. These results further suggest that an index only on the basis of urea does not provide a sufficient measure of dialysis adequacy.

Trimethylamine oxide accumulation as a function of depth in Hawaiian mid-water fishes

Trimethylamine oxide (TMAO) is a common osmolyte and counteracting solute. It is believed to combat the denaturation induced by hydrostatic pressure as some deep-sea animals contain higher TMAO levels than their shallow water counterparts. It has also been proposed that TMAO may accumulate passively during lipid storage resulting in a correlation between lipid content and TMAO levels in some groups. Previous research showed that lipid content decreased with depth in species of Hawaiian fishes presenting a novel test of these competing hypotheses. TMAO ranged from 20.4 to 92.8mmol/kg. Lipid content ranged from 0.50 to 4.7% WW. After completing a comprehensive search for depths available in the literature, provided here, we analyzed TMAO and lipid as a function of average, minimum and maximum depth of occurrence for 27 species of fishes from nine orders. We found that TMAO is positively correlated with all measures of habitat depth (hydrostatic pressure) but the relationship is strongest with average depth. We further showed using phylogenetic independent contrasts that this relationship was not influenced by the evolutionary relatedness of these species. Interestingly, we found that lipid content increased with depth, in direct contrast to previous studies. TMAO is thus also positively correlated with lipid content. While we are unable to distinguish between these hypotheses, we show that TMAO is strongly correlated with depth in mid-water fishes.

Mechanism of Prominent Trimethylamine Oxide (TMAO) Accumulation in Hemodialysis Patients.

Large size, protein binding and intracellular sequestration are well known to limit dialytic removal of compounds. In studying the normal renal and dialytic handling of trimethylamine oxide (TMAO), a molecule associated with cardiovascular disease in the general population, we discovered two largely unrecognized additional limitations to sustained reduction of a solute by chronic hemodialysis. We measured solute levels and handling in subjects on chronic hemodialysis (ESRD, n = 7) and compared these with levels and clearance in normal controls (NLS, n = 6). The ESRD patients had much higher peak predialysis plasma levels of TMAO than NLS (77 ± 26 vs 2±1 μM, mean ± SD, p<0.05). For comparison, predialysis BUN levels in ESRD subjects were 45±11 mg/dl and 15±3 mg/dl in NLS. Thus TMAO levels in ESRD average about 40 fold those in NLS while BUN is 3 fold NLS. However, the fractional reduction of TMAO concentration during dialysis, was in fact greater than that of urea (86±3 vs 74±6%, TMAO vs urea, p < 0.05) and its dialytic clearance while somewhat lower than that of urea was comparable to creatinine’s. Also production rates were similar (533±272 vs 606 ± 220 μ moles/day, ESRD vs NLS, p>0.05). However, TMAO has a volume of distribution about one half that of urea. Also in NLS the urinary clearance of TMAO was high (219±78 ml/min) compared to the urinary urea and creatinine clearances (55±14 and 119±21 ml/min, respectively). Thus, TMAO levels achieve multiples of normal much greater than those of urea due mainly to 1) TMAO’s high clearance by the normal kidney relative to urea and 2) its smaller volume of distribution. Modelling suggests that only much more frequent dialysis would be required to lower levels Thus, additional strategies such as reducing production should be explored. Furthermore, using urea as the sole marker of dialysis adequacy may be misleading since a molecule, TMAO, that is dialyzed readily accumulates to much higher multiples of normal with urea based dialysis prescriptions.

Potential metabolomic biomarkers for evaluation of adriamycin efficacy using a urinary 1H‐NMR spectroscopy

A metabolomics approach using proton nuclear magnetic resonance (NMR) was applied to investigate metabolic alterations following adriamycin (ADR) treatment for gastric adenocarcinoma. After BALB/c-nu/nu mice were implanted with human gastric adenocarcinoma, ADR (1 or 3 mg kg(-1) per day) was intraperitoneally administered for 5 days. Urine was collected on days 2 and 5 and analyzed by NMR. The levels of trimethylamine oxide (TMAO, ×0.3), hippurate (×0.3) and taurine (×0.6) decreased significantly (P < 0.05), whereas the levels of 3-indoxylsulfate (×12.6), trigonelline (×1.5), citrate (×2.5), trimethylamine (TMA, ×2.0) and 2-oxoglutarate (×2.3) increased significantly (P < 0.05) in the tumor model. After ADR treatment, TMAO, hippuarte and taurine were increased significantly on day 5 compared with those of the tumor model. The levels of 2-oxoglutarate, 3-indoxylsulfate, trigonelline, TMA and citrate, which increased in the tumor model, significantly decreased to those of normal control by ADR treatment. Furthermore, the ratio between TMA and TMAO was dramatically altered in both tumor and ADR-treated groups. Overall, metabolites such as TMAO, TMA, 3-indoxylsulfate, hippurate, trigonelline, citrate and 2-oxoglutarate related to the tricarboxylic acid (TCA) cycle might be considered as therapeutic targets to potentiate the efficacy of ADR. Thus, these results suggest that the metabolomics analysis of tumor response to ADR treatment may be applicable for demonstrating the efficacy of anticancer agent, ADR and treatment adaptation.

Chemical chaperoning action of glycerol on the antifreeze protein of rainbow smelt

Rainbow smelt ( Osmerus mordax) accumulate high levels of glycerol and moderate levels of trimethylamine oxide (TMAO) that lower the colligative freezing point of the serum and thereby contribute to seasonal freeze resistance. In the current study, the possibility that one or both of these compounds might also have a chaperoning role at low temperatures in smelt was investigated by studying their effects on the smelt antifreeze protein (AFP). Activity of the AFP in the presence of physiological levels of TMAO and glycerol was observed by means of ice crystal morphology and measured as thermal hysteresis. Ice crystals in AFP solutions were not visibly modified by either compound and TMAO at 25 and 50 mM had no appreciable effect on hysteresis; however, glycerol at 250 and 500 mM increased hysteresis. An equiosmolar level of NaCl was not as effective as glycerol in enhancing hysteresis, suggesting that osmolarity had little or no role. Although cross-linking experiments showed dimerization of AFP to be unchanged in the presence of glycerol, circular dichroism and intrinsic fluorescence analyses revealed enhanced protein folding. As glycerol enhances the folding and consequent activity of smelt AFP, protein chaperoning appears to be an endogenous role of glycerol in this vertebrate species.

Toxicometabolomics of Urinary Biomarkers for Human Gastric Cancer in a Mouse Model

Toxicometabolomics of urinary biomarkers for human gastric cancer in a mouse model was investigated using 1H-nuclear magnetic resonance (NMR) spectroscopy. A human gastric adenocarcinoma cell line (1 × 107 cells/ml) was grafted onto the skin of the back of intact male BALB/c-nu/nu mice. After the xenografted tumors developed, urine was collected and analyzed for endogenous metabolites. Global profiling combined with principal components analysis (PCA), partial least squares-discriminant analysis (PLS-DA), and orthogonal projections to latent squares-discriminant analysis (OPLS-DA) showed distinct separation of clusters between control and tumor-bearing mice. Targeted profiling revealed significant changes in trimethylamine oxide (TMAO), 3-indoxylsulfate, hippurate, and citrate levels in mice carrying human gastric cancer cells compared to normal mice. The levels of TMAO (0.41-fold) and hippurate (0.26-fold) in tumor-bearing mice were significantly decreased, whereas the levels of 3-indoxylsulfate (3.39-fold), 2-oxoglutarate (2.32-fold), and citrate (1.9-fold) were significantly increased in urine samples of tumor-bearing mice. Data suggest that TMAO, hippurate, 3-indoxylsulfate, 2-oxoglutarate, and citrate may serve as useful urinary biomarkers for gastric tumorigenesis in a mouse model.