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Background/Objectives: Hepatic encephalopathy (HE) is characterized by hyperammonemia, neuroinflammation, oxidative stress, and blood–brain barrier (BBB) dysfunction, with brain endothelial cells being highly vulnerable to ammonia-induced damage. Adiponectin is a cytoprotective adipokine that may enhance endothelial resilience; however, its specific role under hyperammonemic conditions remains unclear. This study aims to investigate the protective effects of adiponectin on brain endothelial function and BBB integrity. Methods: In vivo, male C57BL/6J mice underwent bile duct ligation (BDL) surgery and received daily intraperitoneal adiponectin injections (10 μg/kg/day) for 6 days, starting 5 days post-surgery. On day 11, brain tissues and serum were collected for molecular and cytokine analyses. In vitro, mouse brain endothelial cells (bEnd.3) were pretreated with adiponectin before exposure to ammonia. Assays for tight junction preservation, mitochondrial membrane potential, reactive oxygen species (ROS) generation, and total RNA sequencing were performed. Results: In BDL mice, adiponectin increased the expression of the tight junction protein claudin-5 and synaptic marker PSD95 across the cortex, hippocampus, and striatum, while reducing pro-oxidant (Cyp2e1, Cyp4a1) and apoptotic (Caspase-9) markers. In vitro, adiponectin pretreatment maintained tight junction proteins, suppressed inflammatory markers, restored mitochondrial membrane potential, and decreased ROS generation in ammonia-exposed bEnd.3 cells. Transcriptomic profiling revealed that adiponectin modulates stress-related gene expression under hyperammonemic conditions. Conclusions: Adiponectin enhances cellular stress resistance and maintains BBB structural integrity under ammonia-induced toxicity. These findings suggest that adiponectin serves as a promising therapeutic target for mitigating neurovascular unit dysfunction in hepatic encephalopathy.

To achieve sustainable ammonia production, a bioprocessing approach that uses enzymes and hyperammonia-producing bacteria (HAB) was developed to convert soybean meal protein isolate (SMPI) to bio-ammonia—an ammonia and ammonium solution. The potential of multiple industrial proteolytic enzymes (alcalase (A), flavourzyme (B), neutrase (C), and protamex (D)) to produce SMPI-hydrolysates that aid bio-ammonia production was evaluated in separate and simultaneous hydrolysis and fermentation systems. When used singly, the bio-ammonia yield trend was B > A > D > C hydrolysates, which was in line with their degree of hydrolysis (DH). In combination, when two or more enzymes were mixed in the same reaction, AD combination yielded hydrolysates converted to the highest ammonia titer of 1304 mg/L. The enhancement of bio-ammonia production in AD hydrolysates was the combined effect of an increase in the DH and the release of soluble hydrolysates during fermentation. In a multi-enzyme process, enzyme compatibility was more important towards bio-ammonia production. Hydrolyzing SM protein isolates for 6 or 24 h followed by 120 h HAB fermentation produced up to 1.2 g/L bio-ammonia in the separate hydrolysis and fermentation system. However, a peak ammonia titer of ~1.4 g/L was obtained in the simultaneous hydrolysis and fermentation (SHF). Consequently, the use of the enzyme mixture AD in an SHF system improved bio-ammonia production. The result from this work will be valuable for industrial bioprocessing of soybean meal protein to bio-ammonia synthesis.

Background/Objectives: The effects of thermal drying on the viability of beneficial microorganisms immobilized in biochar, as well as on biochar nutrient retention, remain insufficiently understood. This study aimed to evaluate how drying temperature influences the survival of hyper-ammonia-producing bacteria (HAB) immobilized on pine wood biochar and to assess the impact of subsequent storage on bacterial recovery and nutrient stability. Methods: Biochar was inoculated with HAB and subjected to drying at temperatures ranging from 40 to 60 °C. Following drying, samples were characterized and stored for 30 days. Microbial revival was assessed through reculturing, while changes in surface functional groups were analyzed using FTIR spectroscopy. Nutrient retention, particularly nitrogen content, was also evaluated. Results: Higher drying temperatures resulted in reduced immediate microbial revival during reculturing. However, samples exhibiting limited immediate recovery demonstrated enhanced revival after the 30-day storage period. FTIR analysis revealed that drying temperature modified the availability of surface functional groups associated with microbial attachment and activity. Nutrient analysis indicated only minor reductions in nitrogen retention in biochar dried at temperatures above 55 °C. Conclusions: Drying temperature significantly affects both the short-term survival and post-storage recovery of beneficial microorganisms immobilized in biochar. While elevated temperatures may initially suppress microbial activity, recovery potential during storage remains substantial. Optimizing drying conditions is therefore essential to balance microbial viability with nutrient retention in biochar-based formulations.

Hyperammonia-producing bacteria (HAB) are a class of microbes present in the stomach of ruminants, responsible for the rapid rate of ammonia production from protein degradation beyond the capacity of these animals for their utilization. Thus, ruminant nutritionists are interested in decreasing ruminal protein degradation and ammonia genesis by focusing on controlling the activity of HAB. The investigations of the present study were carried out to determine predominant hyperammonia-producing bacteria in the rumen of buffaloes, their isolation and characterization, as well as the inhibition of these isolates with various sources of plant secondary compounds (tannins, saponins, and essential oils). Studies employing high-throughput sequencing of amplicons of the 16S rRNA gene from genomic DNA recovered from enrichment culture of HAB of buffalo rumina indicated that, at the phylum level, Proteobacteria (61.1 to 68.2%) was the most predominant HAB. Acidaminococcus was most predominant among the identified genera. In vitro experiments were conducted with enrichment culture of buffalo rumen contents incubated with different types of feed additives such as essential oils (eucalyptus oil, lemon grass oil, and clove oil) and extracts of plants (Sapindus mukorossi fruits and Ficus bengalensis leaves), each at graded dose levels. The reduction in ammonia production by clove and lemon grass oils was evident due to the presence of major bioactive compounds, especially eugenol and limonene, which have strong antimicrobial activity. However, clove oil and Indian soapberry/reetha (Sapindus mukorossi) fruit were found to be promising and effective in reducing the growth, protease production, and ammonia production of HAB culture.

The modulation of primary nitrogen metabolism by hypoxic stress was studied in young Medicago truncatula seedlings. Hypoxic seedlings were characterized by the up-regulation of glutamate dehydrogenase 1 (GDH1) and mitochondrial alanine aminotransferase (mAlaAT), and down-regulation of glutamine synthetase 1b (GS1b), NADH-glutamate synthase (NADH-GOGAT), glutamate dehydrogenase 3 (GDH3), and isocitrate dehydrogenase (ICDH) gene expression. Hypoxic stress severely inhibited GS activity and stimulated NADH-GOGAT activity. GDH activity was lower in hypoxic seedlings than in the control, however, under either normoxia or hypoxia, the in vivo activity was directed towards glutamate deamination. 15NH4 labelling showed for the first time that the adaptive reaction of the plant to hypoxia consisted of a concerted modulation of nitrogen flux through the pathways of both alanine and glutamate synthesis. In hypoxic seedlings, newly synthesized 15N-alanine increased and accumulated as the major amino acid, asparagine synthesis was inhibited, while 15N-glutamate was synthesized at a similar rate to that in the control. A discrepancy between the up-regulation of GDH1 expression and the down-regulation of GDH activity by hypoxic stress highlighted for the first time the complex regulation of this enzyme by hypoxia. Higher rates of glycolysis and ethanol fermentation are known to cause the fast depletion of sugar stores and carbon stress. It is proposed that the expression of GDH1 was stimulated by hypoxia-induced carbon stress, while the enzyme protein might be involved during post-hypoxic stress contributing to the regeneration of 2-oxoglutarate via the GDH shunt.

Hyperargininemia due to arginase deficiency is a rare, inherited, urea cycle disorder. This is a case report of a 9-year old girl presenting with hyperammonemia, hyperargininemia, with neurological symptoms responding to hemodialysis.

Storage of swine manure is associated with the microbiological production of a variety of odorous compounds, including ammonia, organic acids, and alcohols, phenolics, and sulfides. Until recently, little was known about the microorganisms responsible for their production. Results from our laboratory have demonstrated that the predominant microbial populations of stored swine manure are anaerobic, low (G + C), Gram-positive bacteria. However, studies on pure cultures isolated from manure have found few microorganisms that produce appreciable ammonia concentrations. Therefore, selective and enrichment techniques were employed to isolate ammonia-producing bacteria from stored swine manure by using media containing peptone and amino acids as carbon and energy sources. We now report on the isolation of 40 bacterial cultures, a number of which are capable of producing at least 40 mM ammonia in peptone-amino acid medium, concentrations similar to those produced by hyper-ammonia producing (HAP) bacteria isolated from the rumen of cattle. The manure HAP isolates are phylogenetically distinct from the ruminal isolates and may prove to be intimately involved in the production of ammonia during storage of swine manure.

Cultured H35 hepatoma cells release a cytotoxic factor in response to irradiation with X-rays. When the conditioned medium from irradiated cells is given to nonirradiated cells, growth is inhibited and followed by cell death, possibly apoptosis, Analysis of the conditioned medium reveals a dramatic change in the ornithine (urea) cycle components after the irradiation. A strong decrease in medium arginine is accompanied with parallel increases in ornithine, citrulline and ammonia. The high level of ammonia appears to be largely responsible for the observed cytotoxicity. The development of hyperammonia by irradiated cells and the related toxicity depend on the radiation dose and the number of cells seeded thereafter for the medium conditioning. Development of cytotoxicity by irradiated cells is completely prevented with the arginase inhibitor L -norvaline, in arginine-deficient medium or when citrulline replaces arginine. These preventive measures result in subtoxic ammonia levels.