Latest Articles and News - Jul 13, 2025
post on 13 Jul 2025
Cetobacterium somerae-derived argininosuccinic acid promotes intestinal and liver ureagenesis to alleviate ammonia intoxication.
Ammonia generated from amino acid metabolism is a cytotoxin that can adversely affect cell function and overall health and potentially lead to cellular toxicity and death due to its accumulation. Previous studies have shown that acute ammonia intoxication (AI) can increase the intestinal C. somerae abundance, hinting at a possible involvement of C. somerae in the host's reaction to AI. Nonetheless, the precise mechanism through which C. somerae mitigates the effects of AI is uncertain. This research elucidated the metabolic mechanism of transplanting Cetobacterium somerae ceto (CSC) to assist the host in managing AI. Our results suggest that (I) AI resulted in impaired ureagenesis pathway. This was manifested by elevated levels of ammonia in the blood, liver, and intestines, along with decreased urea levels. (II) Supplementing orally with live CSC facilitated its colonization in the intestines, mitigating AI by reversing depletion of intestinal argininosuccinic acid (ARA) and promoting ureagenesis. (III) CSC synthesized ARA from aspartate and asparagine through the asnA-ansA/B-argG gene cluster. Additionally, CSC assimilated fumaric acid and malic acid from the environment, dampening the degradation of ARA by CSC's fumA-fumB-argH gene cluster. (IV) Live CSC provided ARA support for ureagenesis in the intestine and liver, reducing endogenous ammonia levels of pseudo-sterile yellow catfish. (V) Supplementation of ARA decreased systemic ammonia levels by promoting ureagenesis. Inhibiting the expression of argininosuccinate lyase in the liver through RNA interference can impede arginine synthesis, thereby eliminating the ammonia-lowering effect of ARA. In summary, this study found that the role of probiotics in enhancing the host's resistance to AI depends on the function of ARA generated by CSC. AI can lead to depletion of ARA and interrupting ureagenesis, while CSC-produced ARA supplements ureagenesis in the liver and intestines, facilitating ammonia detoxification into urea. Video Abstract.
https://pubmed.ncbi.nlm.nih.gov/40652219/Acceptability and perceived feasibility of restroom motion sensors for overdose detection and response in public bathrooms: A cross-sectional study of businesses and community organizations.
Solitary drug use amplifies fatal overdose risk for people who use drugs. Restroom motion sensors (RMS) are emerging technologies to enhance detection and facilitate rapid response to overdoses in high-traffic public restrooms (where unmonitored drug use is likely to occur), but there has been limited study of employee and staff perspectives on the perceived value and appropriateness of RMS for their workplaces. From November 2022 to April 2024, we identified business, health, and community organizations in opioid overdose hotspots across eight townships in Rhode Island (United States of America), surveying managers and shift supervisors about the acceptability and perceived feasibility of RMS. We analyzed data descriptively, identifying bivariate correlates of RMS acceptability and feasibility, respectively, using Fisher's exact tests of association. Participants (median age: 35 years, 53 % cisgender women) across 100 workplaces exhibited low awareness (4 %) but high comfort with RMS being installed (73 %) and confidence (66 %) in implementing RMS in their workplaces in the future. Organizations without staff adequately trained in overdose response were more likely than organizations with trained staff (81 % vs. 64 %, p = 0.055) to endorse confidence in RMS implementation. Management and shift supervisors in heterogenous occupational contexts endorsed RMS' compatibility and utility in their workplaces, despite low prior awareness of the technology. Efforts to bolster staff competencies in overdose response and equipping workplaces with the necessary tools (i.e., onsite naloxone) to respond appropriately to onsite overdoses will be imperative to successful implementation of RMS in businesses and community organizations.
https://pubmed.ncbi.nlm.nih.gov/40651080/Computational Study of Catalytic Poisoning Mechanisms in Polypropylene Polymerization: The Impact of Dimethylamine and Diethylamine on the Deactivation of Ziegler-Natta Catalysts and Co-Catalysts.
In this study, density functional theory (DFT) was used to analyze the processes that govern the interactions among triethylaluminum (TEAL), the Ziegler-Natta (ZN) catalyst, and the inhibitory compounds dimethylamine (DMA) and diethylamine (DEA) during olefin polymerization. The structural and charge characteristics of these inhibitors were examined through steric maps and DFT calculations. Combined DFT calculations (D3-B3LYP/6-311++G(d,p)) and IR spectroscopic analysis show that the most efficient way to deactivate the ZN catalyst is via the initial formation of the TEAL·DMA complex. This step has a kinetic barrier of only 27 kcal mol-1 and a negative ΔG, in stark contrast to the >120 kcal mol-1 required to form TEAL·DEA. Once generated, TEAL·DMA adsorbs onto the TiCl4/MgCl2 cluster with adsorption energies of -22.9 kcal mol-1 in the gas phase and -25.4 kcal mol-1 in n-hexane (SMD model), values 5-10 kcal mol-1 more favorable than those for TEAL·DEA. This explains why, although dimethylamine is present at only 140 ppm, its impact on productivity (-19.6%) is practically identical to that produced by 170 ppm of diethylamine (-20%). The persistence of the ν(Al-N) band at ~615 cm-1, along with a >30% decrease in the Al-C/Ti-C bands between 500 and 900 cm-1, the downward shift of the N-H stretch from ~3300 to 3200 cm-1, and the +15 cm-1 increase in ν(C-N) confirm Al←N coordination and blockage of alkyl transfer, establishing the TEAL·DMA → ZN pathway as the dominant catalytic poisoning mechanism.
https://pubmed.ncbi.nlm.nih.gov/40647843/
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