Previous studies showed that large amounts of phenylcarboxylic acids (PhCAs) are accumulated in a septic patient’s blood due to increased endogenous and microbial phenylalanine and tyrosine ...biotransformation. Frequently, biochemical aromatic amino acid transformation into PhCAs is considered functionally insignificant for people without monogenetic hereditary diseases. The blood of healthy people contains the same PhCAs that are typical for septic patients as shown in this paper. The overall serum PhCAs level was 6 μM on average as measured by gas chromatography with flame ionization detection. This level is a stable biochemical parameter indicating the normal metabolism of aromatic amino acids. The concentrations of PhCAs in the metabolic profile of healthy people are distributed as follows: phenylacetic ≈
p
-hydroxyphenyllactic >
p
-hydroxyphenylacetic > phenyllactic ≈ phenylpropionic > benzoic. We conclude that maintaining of stable PhCAs level in the serum is provided as the result of integration of human endogenous metabolic pathways and microbiota.
High concentration of sepsis-associated aromatic microbial metabolites (AMM) stands as a prognostically unfavorable factor, indicating the progression of multiple organ dysfunction and an increased ...risk of death in patients with sepsis and septic shock. This study is based on a hypothesis that excess of sepsis-associated AMM in patients with sepsis is caused by metabolic alterations (dysfunction) in the intestinal microbiota.
The aim of this study
was to compare the potential of normobiota and pathobiota to bio-transform sepsis-associated metabolites of aromatic amino acids tyrosine and phenylalanine, such as phenyllactic acid(PhLA) and 4-hydroxyphenyllactic acid (4-HPhLA).
Materials and methods.
Samples of intestinal contents of patients with septic shock (
N
=10, pathobiota) and healthy volunteers (
N
=9, normobiota) were placed in test tubes with the omnipurpose thioglycol medium. The clinical model of excessive inflow of sepsis-associated AMM into the intestine (for example, from blood or sites of inflammation) was reproduced in the
in vitro
experiment by adding PhLA or 4-HPhLA in clinically significant concentrations (25 mkM) into each test tube with pathobiota and normobiota. After incubation in a thermostat (37°, 24 hours), AMМ concentrations were measured in the samples with pathobiota and normobiota using GC-MS analysis.
Results.
Concentration of AMM decreased within 24 hours in the tubes with normobiota after PhLA or 4-HPhLA were added. In the tubes with pathobiota, no decrease in AMM concentrations was documented after loading with PhLA or 4-HPhLA. Concentrations of PhLA (
P
=0.002) and 4-HPhLA (
P
0.001) were statistically significantly higher in pathobiota samples compared to normobiota.
Conclusion.
The
in vitro
experiment demonstrates that after excessive load with sepsis-associated metabolites (PhLA, 4-HPhLA), the microbiota of healthy people is capable to bio-transform such metabolites to the end products of microbial metabolism, while pathobiota of septic patients exhibits altered biotransformational potential. This data demonstrate that microbiota dysfunction may contribute to the pathogenesis of sepsis.
The growing interest in metabolite circulating in the blood is associated with the accumulation of factual material on the involvement of low-molecular compounds in the development of a number of ...serious diseases. This review reveals the effect of a whole class of chemical compounds― tryptophan metabolites― on various pathological processes. The following keywords were used to find papers published in the PubMed database for the last 10 years: names of natural indole compounds, methods for their detection, nosology of diseases and critical ill patients. The data is presented in sections, which provide data on the study of tryptophan metabolites in a variety of groups of diseases, such as cancer, cardiovascular disease, kidney disease, bowel, mental disorders, atherosclerosis, etc. Particular attention is paid to the role of indole compounds that enter the systemic circulation as a result of microbial biotransformation of tryptophan, serotonin and other indole metabolites, which can be attributed to the "common metabolites" of humans and microbiota. The most interesting clinical studies are summarized in summary tables and figures. A number of indole metabolites are considered as potential biomarkers. The authors of the review substantiate the metabolomic approach to the study of a number of oncological, septic, mental and other intractable diseases, which opens up new possibilities of influence on the pathological process by targeted regulation in the metabolome/microbiome system.
Methods have been developed for the preparation of samples containing organic matrices (natural high-color waters, soils, bottom sediments, aquatic organism tissue) to the determination of mercury ...and other toxic elements (As, Cd, Pb, Se) by different procedures of microwave digestion under elevated pressure (closed systems, vessels with partial removal of the gas phase). It is found that, under optimal oxidative and temperature-time conditions, the partial removal of the gas phase does not lead to losses of volatile elements if sample portions under 2 g are used. The duration of preparation of a series of samples does not exceed 40 min. The detection limits for mercury in the cold vapor atomic absorption spectrometry and for Cd, Pb, As, and Se by electrothermal atomic absorption spectrometry are 5 and 0.13, 6, 13, and 13 μg/kg, respectively. The accuracy of determination is confirmed by the results of analysis of certified reference materials of water and plant materials and also by the standard addition method. The selected conditions of preparation of sludge samples have ensured the determination of mercury by the cold vapor atomic absorption spectrometry in drinking, natural, and sewage waters with a detection limit of 0.07 μg/L.
A method has been developed for the determination of phenylcarboxylic acids (benzoic,
p
-hydroxyphenyllactic,
p
-hydroxyphenylacetic, phenyllactic, 3-phenylpropanoic, and phenylacetic) in blood serum ...by gas chromatography with a flame-ionization detector (
FID
). The quantitative characteristics of analysis obtained with the FID and mass spectrometric detectors are in the same range and exhibit common trends for different groups of samples. It has been shown that the reproducibility of the results increases with the addition of a stage of salting out to the sample preparation procedure. The accuracy of the results is estimated using the added-found method. A possibility of the application of widely used FID to the quantitative determination of phenylcarboxylic acids in blood serum has been demonstrated for routine clinical practice.
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