Changes of Coenzyme A and Acetyl-Coenzyme A Concentrations in Rats after a Single-Dose Intraperitoneal Injection of Hepatotoxic Thioacetamide Are Not Consistent with Rapid Recovery

Energy Metabolites and Indicative Significance of α-Ketoglutarate and α-Ketoglutaramate in Assessing the Progression of Chronic Hepatoencephalopathy

In the example of a rat model with chronic hepatoencephalopathy (HE), changes in the organ morphology of rats affect the balance of metabolites of the tricarboxylic acid (TCA) cycle and metabolites of the glutamine-glutamate (Gln-Glu) cycle, namely α-ketoglutarate (αKG) and α-ketoglutaramate (αKGM), as well as the enzymes associated with them, ω-amidase (ωA) and glutamine transaminase (GTK). This model of rats was obtained as a result of 2-22 weeks of consumption by animals of hepatotoxin thioacetamide (TAA) added to drinking water at a concentration of 0.4 g/L. The control (n = 26) and TAA-induced (n = 55) groups of rats consisted of 11 cohorts each. The control cohorts consisted of 2-4 rats, and the TAA-induced cohorts consisted of 4-7 individuals. Every two weeks, samples of blood plasma, liver, kidney, and brain tissues were taken from the next cohort of rats (a total of 320 samples). By the end of the experiment, irreversible morphological changes were observed in the organs of rats: the weight of the animals was reduced up to ~45%, the weight of the kidneys up to 5%, the brain up to ~20%, and the weight of the liver increased up to ~20%. The analysis revealed: (i) a decrease in the activity of ωA and GTK in the tissues of the brain, kidneys, and liver of rats with chronic HE (by ~3, 40, and 65% and ~10, 60, and 70%, respectively); and (ii) the appearance of a significant imbalance in the content of metabolites of the Gln-Glu cycle, αKG, and αKGM. It is indicative that a ~1.5-12-fold increase in the level of αKG in the blood plasma and tissues of the organs of rats with chronic HE was accompanied by a synchronous, ~1.2-2.5-fold decrease in the level of αKGM. The data obtained indicate an essential involvement of the Gln-Glu cycle in the regulation of energy metabolism in rats under conditions of chronic HE. Attention is focused on the significance of the αKG/αKGM ratio, which can act as a potential marker for diagnosing the degree of HE development.

Effects of Fe-N co-modified biochar on methanogenesis performance, microbial community, and metabolic pathway during anaerobic co-digestion of alternanthera philoxeroides and cow manure

The performance of anaerobic digestion (AD) is susceptible to disturbances in feedstock degradation, intermediates accumulation, and methanogenic archaea activity. To improve the methanogenesis performance of the AD system, Fe-N co-modified biochar was prepared under different pyrolysis temperatures (300,500, and 700 °C). Meanwhile, pristine and Fe-modified biochar were also derived from alternanthera philoxeroides (AP). The aim was to compare the effects of Fe-N co-modification, Fe modification, and pristine biochar on the methanogenic performance and explicit the responding mechanism of the microbial community in anaerobic co-digestion (coAD) of AP and cow manure (CM). The highest cumulative methane production was obtained with the addition of Fe-N-BC500 (260.38 mL/gVS), which was 42.37 % higher than the control, while the acetic acid, propionic acid, and butyric acid concentration of Fe-N-BC were increased by 147.58 %, 44.25 %, and 194.06 % compared with the control, respectively. The co-modified biochar enhanced the abundance of Chloroflexi and Methanosarcina in the AD system. Metabolic pathway analysis revealed that the increased methane production was related to the formation and metabolism of volatile fatty acids and that Fe-N-BC500 enhanced the biosynthesis of coenzyme A and the cell activity of microorganisms, accelerating the degradation of propionic acid and enhancing the hydrogenotrophic methanogenesis pathway. Overall, Fe-N co-modified biochar was proved to be an effective promoter for accelerated methane production during AD.

Cerebrospinal fluid exploratory proteomics and ketamine metabolite pharmacokinetics in human volunteers after ketamine infusion

Ketamine is a treatment for both refractory depression and chronic pain syndromes. In order to explore ketamine's potential mechanism of action and whether ketamine or its metabolites cross the blood brain barrier, we examined the pharmacokinetics of ketamine and its metabolites-norketamine (NK), dehydronorketamine (DHNK), and hydroxynorketamines (HNKs)-in cerebrospinal fluid (CSF) and plasma, as well as in an exploratory proteomic analysis in the CSF of nine healthy volunteers who received ketamine intravenously (0.5 mg/kg IV). We found that ketamine, NK, and (2R,6R;2S,6S)-HNK readily crossed the blood brain barrier. Additionally, 354 proteins were altered in the CSF in at least two consecutive timepoints (p < 0.01). Proteins in the classes of tyrosine kinases, cellular adhesion molecules, and growth factors, including insulin, were most affected, suggesting an interplay of altered neurotransmission, neuroplasticity, neurogenesis, synaptogenesis, and neural network functions following ketamine administration.

Sodium Butyrate as Key Regulator of Mitochondrial Function and Barrier Integrity of Human Glomerular Endothelial Cells

The gut microbiota has emerged as an important modulator of cardiovascular and renal homeostasis. The composition of gut microbiota in patients suffering from chronic kidney disease (CKD) is altered, where a lower number of bacteria producing short chain fatty acids (SCFAs) is observed. It is known that SCFAs, such as butyrate and acetate, have protective effects against cardiovascular diseases and CKD but their mechanisms of action remain largely unexplored. In the present study, we investigated the effect of butyrate and acetate on glomerular endothelial cells. Human glomerular microvascular endothelial cells (hgMVECs) were cultured and exposed to butyrate and acetate and their effects on cellular proliferation, mitochondrial mass and metabolism, as well as monolayer integrity were studied. While acetate did not show any effects on hgMVECs, our results revealed that butyrate reduces the proliferation of hgMVECs, strengthens the endothelial barrier through increased expression of VE-cadherin and Claudin-5 and promotes mitochondrial biogenesis. Moreover, butyrate reduces the increase in oxygen consumption induced by lipopolysaccharides (LPS), revealing a protective effect of butyrate against the detrimental effects of LPS. Taken together, our data show that butyrate is a key player in endothelial integrity and metabolic homeostasis.

Residual Amino Acid Imbalance in Rats during Recovery from Acute Thioacetamide-Induced Hepatic Encephalopathy Indicates Incomplete Healing

The delayed consequences of the influence of hepatic encephalopathy (HE) on the metabolism of animals have not been studied enough. We have previously shown that the development of acute HE under the influence of the thioacetamide (TAA) toxin is accompanied by pathological changes in the liver, an imbalance in CoA and acetyl CoA, as well as a number of metabolites of the TCA cycle. This paper discusses the change in the balance of amino acids (AAs) and related metabolites, as well as the activity of glutamine transaminase (GTK) and ω-amidase enzymes in the vital organs of animals 6 days after a single exposure to TAA. The balance of the main AAs in blood plasma, liver, kidney, and brain samples of control (n = 3) and TAA-induced groups (n = 13) of rats that received the toxin at doses of 200, 400, and 600 mg/kg was considered. Despite the apparent physiological recovery of the rats at the time of sampling, a residual imbalance in AA and associated enzymes persisted. The data obtained give an idea of the metabolic trends in the body of rats after their physiological recovery from TAA exposure and may be useful for prognostic purposes when choosing the necessary therapeutic agents.

Tricarboxylic Acid Metabolite Imbalance in Rats with Acute Thioacetamide-Induced Hepatic Encephalopathy Indicates Incomplete Recovery

Exposure to the toxin thioacetamide (TAA) causes acute hepatic encephalopathy (HE), changes in the functioning of systemic organs, and an imbalance in a number of energy metabolites. The deferred effects after acute HE development are poorly understood. The study considers the balance of the tricarboxylic acid (TCA) cycle metabolites in the blood plasma, liver, kidneys, and brain tissues of rats in the post-rehabilitation period. The samples of the control (n = 3) and TAA-induced groups of rats (n = 13) were collected six days after the administration of a single intraperitoneal TAA injection at doses of 200, 400, and 600 mg/kg. Despite the complete physiological recovery of rats by this date, a residual imbalance of metabolites in all the vital organs was noted. The results obtained showed a trend of stabilizing processes in the main organs of the animals and permit the use of these data both for prognostic purposes and the choice of potential therapeutic agents.

CoA in Health and Disease

Coenzyme A (CoA) and its thioester derivatives are crucial components of numerous biosynthetic and degradative pathways of the cellular metabolism (including fatty acid synthesis and oxidation, the Krebs cycle, ketogenesis, cholesterol and acetylcholine biosynthesis, amino acid degradation, and neurotransmitter biosynthesis), post-translational modifications of proteins, and the regulation of gene expression [...].

Human N-Acetyltransferase 1 and 2 Differ in Affinity Towards Acetyl-Coenzyme A Cofactor and N-Hydroxy-Arylamine Carcinogens

Arylamine N-acetyltransferases catalyze the transfer of acetyl groups from the endogenous cofactor acetyl coenzyme A (AcCoA) to arylamine (N-acetylation) and N-hydroxy-arylamine (O-acetylation) acceptors. Humans express two arylamine N-acetyltransferase isozymes (NAT1 and NAT2) which catalyze both N- and O-acetylation but differ in genetic regulation, substrate selectivity, and expression in human tissues. We investigated recombinant human NAT1 and NAT2 expressed in an Escherichia coli JM105 and Schizosaccharomyces pombe expression systems as well as in Chinese hamster ovary (CHO) cells to assess the relative affinity of AcCoA for human NAT1 and NAT2. NAT1 and NAT2 affinity for AcCoA was higher for recombinant human NAT1 than NAT2 when catalyzing N-acetylation of aromatic amine carcinogens 2-aminofluroene (AF), 4-aminobiphenyl (ABP), and β-naphthylamine (BNA) and the metabolic activation of N-hydroxy-2-aminofluorene (N-OH-AF) and N-hydroxy-4-aminobiphenyl (N-OH-ABP) via O-acetylation. These results suggest that AcCoA level may influence differential rates of arylamine carcinogen metabolism catalyzed by NAT1 and NAT2 in human tissues. Affinity was higher for NAT2 than for NAT1 using N-OH-AF and N-OH-ABP as substrate consistent with a larger active site for NAT2. In conclusion, following recombinant expression in bacteria, yeast, and CHO cells, we report significant differences in affinity between human NAT1 and NAT2 for its required co-factor AcCoA, as well as for N-hydroxy-arylamines activated via O-acetylation. The findings provide important information to understand the relative contribution of human NAT1 vs NAT2 towards N-acetylation and O-acetylation reactions in human hepatic and extrahepatic tissues.