Genotoxicity Assessment of Haloacetaldehyde Disinfection Byproducts via a Simplified Yeast-Based Toxicogenomics Assay.

Haloacetaldehydes (HALs) represent the third-largest category of disinfection byproducts (DBPs) in drinking water in terms of weight. As a subset of unregulated DBPs, only a few HALs have undergone assessment, yielding limited information regarding their genotoxicity mechanisms. Herein, we developed a simplified yeast-based toxicogenomics assay to evaluate the genotoxicity of five specific HALs. This assay recorded the protein expression profiles of eight Saccharomyces cerevisiae strains fused with green fluorescent protein, including all known DNA damage and repair pathways. High-resolution real-time pathway activation data and protein expression profiles in conjunction with clustering analysis revealed that the five HALs induced various DNA damage and repair pathways. Among these, chloroacetaldehyde and trichloroacetaldehyde were found to be positively associated with genotoxicity, while dichloroacetaldehyde, bromoacetaldehyde, and tribromoacetaldehyde displayed negative associations. The protein effect level index, which are molecular end points derived from a toxicogenomics assay, exhibited a statistically significant positive correlation with the results of traditional genotoxicity assays, such as the comet assay (rp = 0.830 and p < 0.001) and SOS/umu assay (rp = 0.786 and p = 0.004). This yeast-based toxicogenomics assay, which employs a minimal set of gene biomarkers, can be used for mechanistic genotoxicity screening and assessment of HALs and other chemical compounds. These results contribute to bridging the knowledge gap regarding the molecular mechanisms underlying the genotoxicity of HALs and enable the categorization of HALs based on their distinct DNA damage and repair mechanisms.

Preliminary study on the effect of catabolite repression gene knockout on p-nitrophenol degradation in Pseudomonas putida DLL-E4.

P-nitrophenol (PNP) is a carcinogenic, teratogenic, and mutagenic compound that can cause serious harm to the environment. A strain of Pseudomonas putida DLL-E4, can efficiently degrade PNP in a complex process that is influenced by many factors. Previous studies showed that the expression level of pnpA, a key gene involved in PNP degradation, was upregulated significantly and the degradation of PNP was obviously accelerated in the presence of glucose. In addition, the expression of crc, crcY, and crcZ, key genes involved in catabolite repression, was downregulated, upregulated, and upregulated, respectively. To investigate the effect of the carbon catabolite repression (CCR) system on PNP degradation, the crc, crcY, and crcZ genes were successfully knocked out by conjugation experiments. Our results showed that the knockout of crc accelerated PNP degradation but slowed down the cell growth. However, the knockout of crcY or crcZ alone accelerated PNP degradation when PNP as the sole carbon source, but that knockout slowed down PNP degradation when glucose was added. The results indicate that the CCR system is involved in the regulation of PNP degradation, and further work is required to determine the details of the specific regulatory mechanism.

Internal branch of superior laryngeal nerve block by dexamethasone alleviates sore throat after thyroidectomy: a randomized controlled trial.

PURPOSE: Postoperative sore throat (POST) is a common complaint following thyroidectomy. Dexamethasone was reported to alleviate POST when administered via different routes. This study aimed to compare the effects of local spray and perineural injection surrounding the internal branch of superior laryngeal nerve (iSLN) in preventing POST and alleviating postoperative impaired voice function. METHODS: A randomized, double-blinded, controlled trial was performed to test the efficacy of the iSLN block in inhibiting of POST. A total of 161 patients who underwent elective thyroidectomy were randomly allocated to two groups. Group Spray: 4 mg dexamethasone was sprayed on to the vocal cord; Group iSLN: bilateral perineural injection with 4 mg dexamethasone around the iSLN. The incidence and severity of POST, swallowing pain, and its side effects were evaluated. Postoperative acoustic analysis, including jitter and shimmer, was also performed. RESULTS: Group iSLN exhibited a significantly less incidence and intensity of POST at 6 h and 24 h (P < 0.001). The patients experienced less swallowing pain at 6 h (P < 0.001) after the surgery, compared with Group Spray. When compared with Group Spray, Group iSLN improved postoperative voice function, which was characterized by lower jitter and lower shimmer value at 6 h and 24 h (P < 0.001) after the surgery. The severity of postoperative cough is higher in Group Spray (P < 0.001). CONCLUSIONS: Among patients undergoing elective thyroidectomy, those who received perineural injection surrounding iSLN with dexamethasone had improved voice function and presented with more excellence in the inhibition of POST and cough, in comparison with the local spray. REGISTER INFORMATION: This trial was registered in the Chinese Clinical Trial Registry on 4th Jan, 2021 (ChiCTR2100042145). The trial is registered at http://www.chictr.org.cn/showproj.aspx?proj=120142 .

KCC2 receptor upregulation potentiates antinociceptive effect of GABAAR agonist on remifentanil-induced hyperalgesia.

GABAergic system disinhibition played an important role in the pathogenesis of remifentanil-induced hyperalgesia (RIH). K+-Cl--cotransporter-2 (KCC2) has the potential to enhance the strength of GABAergic signaling function. However, few reports have focused on the additive analgesic effect of KCC2 enhancer and GABAA receptor agonist on the spinal dorsal horn. Therefore, we evaluated the role of GABA type A receptor (GABAAR) agonist (muscimol), KCC2 enhancer (CLP257) in remifentanil-induced hyperalgesia, as well as GABA and KCC2 receptors responses in the dorsal spinal horn. Remifentanil started to reduce paw withdrawal mechanical thresholds at postoperative 4 h and lasted to 72 h. The RIH associated decreases in spinal GABA release was transient. The amount of spinal GABA transmitter by microdialysis was observed to be decreased at the beginning and reached bottom at 150 min, then returned to the baseline level at 330 min. The synthesis and transportation of GABA transmitter were inhibited, characterized as spinal GAD67 and GAT1 downregulation after the establishment of RIH model. The effect of RIH on GABA receptor downregulation was linked to the reduced expression of spinal KCC2 receptor. This decrease in KCC2 expression has coincided with an early loss of GABA inhibition. KCC2 enhancer, which is reported to lead to a reduction in intracellular Cl-, can enhance GABA-mediated inhibitory function. Both muscimol and CLP257 could dose-dependently inhibit mechanical hypersensitivity caused by remifentanil-induced downregulation of GABAAα2R and KCC2, respectively. Compared with muscimol acting alone, the joint action of CLP257 and muscimol showed a higher pain threshold and less c-fos expression via upregulation of KCC2 and GABAAα2R. Taken together, these findings suggested that the RIH was initiated by decreased GABA release. Downregulation of GABAAα2R and KCC2 receptor contributed to spinally mediated hyperalgesia in RIH. KCC2 enhancer was proved to potentiate antinociceptive effect of GABAAR agonist in RIH.