Trimethylamine-N-oxide (TMAO) has been suggested as a marker and mediator of cardiovascular diseases. However, data are contradictory, and the mechanisms are obscure. Strikingly, the role of the TMAO precursor trimethylamine (TMA) has not drawn attention in cardiovascular studies even though toxic effects of TMA were proposed several decades ago. We assessed plasma TMA and TMAO levels in healthy humans (HH) and cardiovascular patients qualified for aortic valve replacement (CP). The cytotoxicity of TMA and TMAO in rat cardiomyocytes was evaluated using an MTT test. The effects of TMA and TMAO on albumin and lactate dehydrogenase (LDH) were assessed using fluorescence correlation spectroscopy. In comparison to HH, CP had a two-fold higher plasma TMA (p < 0.001) and a trend towards higher plasma TMAO (p = 0.07). In CP plasma, TMA was inversely correlated with an estimated glomerular filtration rate (eGFR, p = 0.002). TMA but not TMAO reduced cardiomyocytes viability. Incubation with TMA but not TMAO resulted in the degradation of the protein structure of LDH and albumin. In conclusion, CP show increased plasma TMA, which is inversely correlated with eGFR. TMA but not TMAO exerts negative effects on cardiomyocytes, likely due to its disturbing effect on proteins. Therefore, TMA but not TMAO may be a toxin and a marker of cardiovascular risk.

Trimethylamine-oxide (TMAO) is present in seafood which is considered to be beneficial for health. Deep-water animals accumulate TMAO to protect proteins, such as lactate dehydrogenase (LDH), against hydrostatic pressure stress (HPS). We hypothesized that TMAO exerts beneficial effects on the circulatory system and protects cardiac LDH exposed to HPS produced by the contracting heart. Male, Sprague-Dawley and Spontaneously-Hypertensive-Heart-Failure (SHHF) rats were treated orally with either water (control) or TMAO. In vitro, LDH with or without TMAO was exposed to HPS and was evaluated using fluorescence correlation spectroscopy. TMAO-treated rats showed higher diuresis and natriuresis, lower arterial pressure and plasma NT-proBNP. Survival in SHHF-control was 66% vs 100% in SHHF-TMAO. In vitro, exposure of LDH to HPS with or without TMAO did not affect protein structure. In conclusion, TMAO reduced mortality in SHHF, which was associated with diuretic, natriuretic and hypotensive effects. HPS and TMAO did not affect LDH protein structure.

Quantitative description of biochemical processes inside living cells and at single-molecule levels remains a challenge at the forefront of modern instrumentation and spectroscopy. This paper demonstrates such single-cell, single-molecule analyses...

The efficient delivery of drugs to cells depends on their diffusion through the extracellular matrix (ECM) of tissues. Here we present a study of diffusion of nanoprobes of radius from...

Background. There is an ongoing debate whether trimethylamine-oxide (TMAO), a molecule present in seafood and a derivate of microbiota metabolism, is beneficial or harmful for the circulatory system. Interestingly, deep-water animals accumulate TMAO that protects proteins such as lactate dehydrogenase (LDH) against high hydrostatic pressure. We hypothesized that TMAO may benefit the circulatory system by protecting cardiac LDH exposed to hydrostatic stress (HS) produced by contracting heart.Methods and Results. Male, 6-week-old, Sprague-Dawley (SD, n=40) and Spontaneously-Hypertensive-Heart-Failure (SHHF n=18) rats were divided into either Water or TMAO oral treatment. After 56 weeks, half of Water and TMAO SD rats were given isoprenaline (ISO) to produce catecholamine stress. In vitro, LDH with or without TMAO was exposed to HS (changes in pressure 0-250mmHg x 280min -1 ) and was evaluated using fluorescence correlation spectroscopy. After 58 weeks of the treatment survival was 100% in SD-Water, SD-TMAO, ISO-TMAO and 90% in ISO-Water. In SHHF-Water survival was 66% vs 100% in SHHF-TMAO. In general, TMAO-treated rats showed higher diuresis and natriuresis. In comparison to SHHF-Water, SHHF-TMAO showed significantly lower diastolic arterial blood pressure, plasma NT-proBNP and expression of angiotensinogen and AT1 receptors in the heart. In separate experiments, intravenous TMAO but not vehicle or urea significantly increased diuresis in SD. In vitro, exposure of LDH to HS with or without TMAO did not affect the protein structure.Conclusions. TMAO reduces mortality in SHHF rats that is associated with diuretic, natriuretic and hypotensive effects. HS produced by the contracting heart is neutral for cardiac LDH structure. Study protocolSix-week-old SHHF (n=18) and SD (n=40) were randomly assigned to either Water group (rats drinking tap water) or TMAO group (rats drinking TMAO solution in tap water, TMAO -abcr GmbH -Karlsruhe, Germany, 333 mg/l). The dose of TMAO have been selected in order to increase plasma TMAO concentration by 3-5 times (to mimic possible physiological concentrations) and to avoid suprapharmacological effects of TMAO, based on our previous study [7]. Rats were housed in groups of 2-3 animals, in polypropylene cages with environmental enrichment, 12hrs light/12hrs dark cycle, temperature 22-23 o C, humidity 45-55%, fed standard laboratory diet (0.19 % Na, Labofeed B standard, Kcynia, Poland) and water ad libitum. SHHF-TMAO (n=9), SHFF-Water (n=9), SD-TMAO (n=10), SD-Water (n=10) were not subjected to any interventions except of standard animal care until the age of 58 weeks. At the age of 56 weeks ISO-Water (n=10) and ISO-TMAO (n=10) series were given (s.c.) isoprenaline at a dose of 100 mg/kg b.w. (isoprenaline hydrochloride, Sigma-Aldrich, SaintLouis, MO, USA) to produce catecholamine stress as previously described by others [19]. The experimental protocol is depicted in Fig. 1. Experimental protocol in SD and SHHF58-week-old rats were maintained in metabolism cages for 2 days to evaluate 24hr...

The oxazole yellow dye, YOYO-1 (a symmetric homodimer), is a commonly used molecule for staining DNA. We applied the brightness analysis to study the intercalation of YOYO-1 into the DNA. We distinguished two binding modes of the dye to dsDNA: mono-intercalation and bis-intercalation. Bis-intercalation consists of two consecutive mono-intercalation steps, characterised by two distinct equilibrium constants (with the average number of base pair per binding site equals 3.5): K1=3.36±0.43×107M−1 and K2=1.90±0.61×105M−1, respectively. Mono-intercalation dominates at high concentrations of YOYO-1. Bis-intercalation occurs at low concentrations.

No abstract

Increased plasma level of trimethylamine N-oxide (TMAO), a liver metabolite of gut bacteria-produced trimethylamine (TMA), has been suggested to increase cardiovascular risk. Mechanisms of TMAO increase in plasma and biological effects of TMAO are obscure. We evaluated the impact of heart failure (HF) on plasma levels of TMA and TMAO, and biological effects of the molecules. Gut permeability was evaluated in male, 58-week-old Spontaneously Hypertensive Heart Failure (SHHF) and Wistar-Kyoto (WKY) rats. TMA and TMAO levels were assessed using LC-MS. Mean arterial blood pressure (MABP) was measured in anaesthetized, male, 16-week-old WKY treated intravenously with either 0.9% NaCl (vehicle), TMA or TMAO. The cytotoxicity of TMA and TMAO in human vascular smooth muscle cells (hVSMCs) was evaluated using MTT assay. The effect of TMA and TMAO on protein structure of bovine albumin was assessed by fluorescence correlation spectroscopy. WKY showed no pathological changes in the circulatory system. SHHF showed HF with reduced ejection fraction. In comparison to WKY, SHHF had a significantly higher plasma level (μM) of TMA (99.05±6.40 vs 149.30±21.87) and TMAO (5.22±0.61 vs 6.69±0.67). SHHF had a significantly higher plasma-to-stool ratio of TMA, decreased intestinal blood flow and morphological alterations in the colon indicating the increased gut-to-blood penetration of TMA due to HF-induced leaky gut. In WKY treatment with the vehicle and TMAO did not affect MABP. In contrast, TMA (at equimolar doses to TMAO) significantly increased MABP by 5-40 mmHg in a dose dependent manner. In vitro, TMA at a concentration of 500μM reduced hVSMCs viability. TMAO at a concentration of 100mM was not cytotoxic whereas TMA at the same concentration killed cells within 24h. Finally, the incubation of albumin with TMA but not with TMAO resulted in the degradation of the protein structure. In conclusion, HF rats show increased plasma TMA and TMAO, which results from increased gut-to-blood penetration of TMA, a TMAO precursor. TMA but not TMAO affects hemodynamics in rats, reduces viability of cells and degrades protein structure. Therefore, TMA but not TMAO may exert deleterious effects on the circulatory system. Further clinical studies should evaluate not only TMAO but also TMA.