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TMA N-oxide

TMA is normally formed from dietary choline and lecithin, but also from TMA N-oxide by intestinal bacteria (Fig. 7.4.2). Choline bound to lecithin is present most abundantly in egg yolk, liver, kidney legumes, soy beans and peas. TMA N-oxide is present in considerable amounts in marine fish, amounting to approximately... [Pg.782]

Fig. 7.4.3a,b Nuclear magnetic resonance (NMR 500 MHz) urine spectra from a patient with severe trimethylaminuria, a Before eating sea fish (TMA = 44 pmol/mmol creatinine, TMA N-oxide not detectable), b After a 300-g sea fish meal [Nijmegen protocol urine collection during the 6-h postprandial period TMA = 322 pmol/mmol creatinine, TMA N-oxide (TMA + TMA N-oxide) = 84%]. The NMR spectrum shows the presence of increased TMA in the pre-load sample as well as the absence of TMA N-oxide. After eating fish the TMA concentration is very high and the ratio is clearly abnormal... [Pg.785]

Calibration maybe performed based on peak area ratio (TMAiTSP and TMA N-ox-ide TSP). As creatinine also gives a signal in the proton NMR spectrum (3.13 ppm at pH 2.5), it is also possible to directly calculate the TMA and TMA N-oxide concentrations per mmol creatinine. [Pg.786]

For quantification of TMA and TMA N-oxide, the area under the curve of the TMA and TMA N-oxide resonances (both nine equivalent protons) and of the creatinine methyl group resonance (three equivalent protons) is calculated by peak integration. Correction for the number of contributing protons and dividing the TMA and... [Pg.786]

TMA N-oxide peak areas by the creatinine peak area will provide the concentration of both analytes per mmol creatinine. Often the ratio TMA (TMA + TMA N-oxide) or the ratio TMA N-oxide (TMA + TMA N-oxide) is used for post-analytical interpretation. [Pg.787]

Normal persons excrete very little TMA in the urine. However, slight TMA excretion may be observed after meals with a high content of TMA precursors like choline or lecithin, or after eating marine fish due to its high TMA N-oxide content. Healthy women may have a short episode of trimethylaminuria at the onset and during menstruation. TMA has also found to be increased in the urine of some patients using carnitine supplementation. Advanced liver and renal disease may result in TMA excretion and this constitutes the so-called secondary trimethylaminurias. [Pg.787]

All reagents are commercially available. For the gas chromatography approach, isopropylamine may be used as an internal standard [28]. It is dried over granular calcium chloride. TMA is purchased as the hydrochloride salt and TMA N-oxide as the dehydrate (Sigma, UK). TMA and TMA N-oxide are stored in desiccators over silica gel and are heated at 105 C for 2 h prior to use [28]. For head-space mass spectrometry, [2H9]-TMA is purchased from Cambridge Isotope Laboratories (UK) [27]. [Pg.788]

For the isotope dilution, mass spectrometry method samples are injected directly into the gas sample injection port of the mass spectrometer [27]. These techniques do not allow concurrent analysis of TMA and TMA N-oxide in the sample. TMA N-oxide is quantified indirectly by measuring the increase in TMA after chemical reduction. [Pg.788]

Urine (5 ml) urine spiked with 0.2% (v/v) isopropylamine is placed in a screw-capped 15-ml vial [28]. Pelleted potassium hydroxide (3 g) is added before sealing the vial with an airtight polytetrafluoroethylene-lined septum cap. Potassium hydroxide raises the pH of the sample to ensure that the amines are present as volatile bases. The vial is heated in an aluminium block at 90 C for 20 min. While still in this block, 2 ml head-space gas is withdrawn through the septum with a disposable syringe and injected immediately on the gas chromatography column. The operating temperatures of the column, injector port and detector unit are 70 C isothermal, 150 C and 200 C, respectively, with nitrogen carrier gas at 60 ml/min. This allows quantification of TMA and other amines. TMA N-oxide is measured after quantitative reduction into TMA. For this, titanous chloride (30%, w/v 0.2 ml) is added to 2 ml urine in a screw-capped vial and incubated for 30 min at room temperature. The sample is then diluted ten-fold with distilled water and analysed as described above. The result represents the sum of TMA and TMA N-oxide present in the sample. [Pg.789]

Healthy volunteers excrete 93.2-97.9% of the ingested TMA as TMA N-oxide. Parents of patients with trimethylaminuria excreted only 74.8-78.9% of the 600 mg TMA dose as TMA N-oxide [2]. Urine generally is collected during 6-8 h after the TMA ingestion. [Pg.789]

Fig. 7.4.4 Oral challenge test with a sea fish meal (300 g fresh sea fish) in two healthy volunteers (---) and one patient with the severe form of trimethylaminuria. The ability of the N-oxida-tion system to oxidise TMA into TMA N-oxide is expressed as the ratio TMA N-oxide (TMA N-oxide + TMA). In this patient both the baseline value and all other data points are abnormal... Fig. 7.4.4 Oral challenge test with a sea fish meal (300 g fresh sea fish) in two healthy volunteers (---) and one patient with the severe form of trimethylaminuria. The ability of the N-oxida-tion system to oxidise TMA into TMA N-oxide is expressed as the ratio TMA N-oxide (TMA N-oxide + TMA). In this patient both the baseline value and all other data points are abnormal...
TMA is a volatile aliphatic tertiary amine with a pungent odour resembling rotting fish (Fig. 7.4.1). TMA has a 100-fold greater olfactory potency than its N-oxide. The reported threshold odour for TMA is 0.9 ppm. Exposure to concentrations above 20 ppm gives moderate irritation of the respiratory system and the eyes. Dermal contact with a concentrated aqueous solution may cause severe burns [4]. Oral ingestion of 15 mg TMA hydrochloride/kg body weight induces nausea and ichthyo-hydrosis [9]. [Pg.782]

TMA is normally cleared effectively from the human blood circulation by hepatic N-oxidation and urinary excretion of the resulting non-odourous N-oxide. TMA in human metabolism is predominantly (>95%) N-oxidised, but N-demethylation towards dimethylamine also occurs (Fig. 7.4.2) [3,5]. [Pg.783]

Several methods are available in the literature for the measurement of aliphatic amines in biological samples [28]. Problems with specificity and separation and cumbersome derivatisation and/or extraction procedures have limited the use of these techniques on a larger scale in clinical practice. The lack of a simple analytical method may have led to an underestimation of the incidence of the fish odour syndrome. For diagnosing the syndrome, an analytical technique should be used that is able to simultaneously and quantitatively measure TMA and its N-oxide in the complex matrix of human urine. Two such methods are currently available for this purpose proton nuclear magnetic resonance (NMR) spectroscopy and head-space gas analysis with gas chromatography or direct mass spectrometry (see below). [Pg.784]

TMA, its N-oxide and related aliphatic amines like methylamine and dimethylamine in urine may be quantified using head-space gas chromatography [28] or direct injection of the head-space gas into the gas sample injection port of a mass spectrometer [27]. These methods take advantage of the volatility of the amines and evaluate the amine-rich head-space gas generated above the sample by direct injection. The... [Pg.787]

Various bacteria grow anaerobically using trimethylamine-N-oxide (TMAO) as an alternative electron acceptor of a respiratory transport chain (31, 32). The energy-yielding reaction involves the conversion of TMAO to tetramethylamine (TMA) catalyzed by a TMAO reductase (TMAOR). [Pg.540]

Recently metabolism by intestinal microbiota of dietary L-carnitine, abundant in red meat to trimethylamine (TMA), which is then transformed into trimethylamine-N-oxide (TMAO) in the liver has been shown to accelerate... [Pg.23]

Metabolism of the dietary lipid phosphatidylcholine by gut bacteria generates trimethylamine (TMA), which is then oxidized into trimethylamine N-oxide (TMAO) by hepatic flavin mono-oxygenase (FMO). FMO expression is induced by the BA nuclear receptor FXR, upon stimulation with BA. TMAO is implicated in the formation of atherosclerotic plaque through induction of upregulation of the expression of two macrophage scavenger receptors, CD36 and SR-Al 7° Additionally TMAO were recently shown to inhibit reverse cholesterol transport (RCT),... [Pg.132]

NMR spectroscopy can be used to find inborn errors of metabolism characterised by the presence of metabolites that cannot be detected with conventional screening methods. Trimethylaminuria or fish odour syndrome may serve as an example [9]. It is a hereditary disease based on an enzyme deficiency in the liver. Trimethylamine (=TMA) derives from bacteria that convert it from dietary choline. Normally there is an enzyme in the liver that oxidizes TMA efficiently. TMA and trimethylamine N-oxide (=TMAO) are both secreted in the urine. TMA has the smell of rotten fish causing a social problem for the patient. Until recently no technique could measure TMA and TMAO simultaneously to prove this deficiency at the metabolic level. This is very well possible with NMR spectroscopy. [Pg.85]

Fig. 13.3. Cod fish quality change during storage (according to Ludorff, 1973). Sensory evaluation in total 15 points are given, 5 for visual appearance and 10 for odor, taste and texture Q-value electric resistance of the fish tissue as recorded by a fish tester Q40 quality class S, Q = 30-40 A, Q = 20-30 B, Q20 C and worse TMAO-N trimethylamine oxide-N TVB-N total volatile base-N VRS volatile reducing substances, TMA-N trimethylamine-N... Fig. 13.3. Cod fish quality change during storage (according to Ludorff, 1973). Sensory evaluation in total 15 points are given, 5 for visual appearance and 10 for odor, taste and texture Q-value electric resistance of the fish tissue as recorded by a fish tester Q40 quality class S, Q = 30-40 A, Q = 20-30 B, Q20 C and worse TMAO-N trimethylamine oxide-N TVB-N total volatile base-N VRS volatile reducing substances, TMA-N trimethylamine-N...
FIGURE 6.1 Factors that influence the nature of electrostatic cation adsorption at oxide surfaces, and thus, PL membrane structure, (a) Percentage of surface sites occupied by TMA+ ions compared to Na+ ions. This number is another way of representing AGexcTMA+/Na+. (b) Standard state entropy of cation adsorption. (Modified and reprinted from Sahai, N., J. Colloid Interface Sci., 252, 309, copyright 2002, and Sahai, N., Geochim. Cosmochim. Acta, 64, 3629, copyright 2000. With permission from Elsevier Science.)... [Pg.158]

P.Y. Zavalij, T. Chirayil, and M.S. Whittingham, Layered tetramethylammonium vanadium oxide [N(CH3)4]V307 by x-ray Rietveld refinement, Acta Cryst. C53, 879 (1997) tma - tetramethylammonium [N(CH3)4]. The material in a form of a black crystalline powder was prepared by hydrothermal treatment at 185°C of a mixture of V2O5, tmaOH, and LiOH taken in 1 2 1 molar ratio and acidified with CH3COOH to pH = 6,5. [Pg.561]

PhIO] = iodosylbenzene PPO = polypropylene oxide TBA, THA, THA = tetra-n-butylammonium, tetra-n-hexylammonium, and tetra-n-heptylammonium, respectively TMA — tetramethylammonium ... [Pg.718]


See other pages where TMA N-oxide is mentioned: [Pg.782]    [Pg.782]    [Pg.782]    [Pg.784]    [Pg.787]    [Pg.790]    [Pg.790]    [Pg.782]    [Pg.782]    [Pg.782]    [Pg.784]    [Pg.787]    [Pg.790]    [Pg.790]    [Pg.248]    [Pg.783]    [Pg.785]    [Pg.789]    [Pg.11]    [Pg.107]    [Pg.70]    [Pg.69]    [Pg.70]    [Pg.726]    [Pg.21]    [Pg.40]    [Pg.92]    [Pg.58]    [Pg.661]    [Pg.735]    [Pg.485]    [Pg.454]   
See also in sourсe #XX -- [ Pg.786 ]




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