Neurotoxicity of fine and ultrafine particulate matter: A comprehensive review using a toxicity pathway-oriented adverse outcome pathway framework.

Fine particulate matter (PM2.5) can cause brain damage and diseases. Of note, ultrafine particles (UFPs) with an aerodynamic diameter less than or equal to 100 nm are a growing concern. Evidence has suggested toxic effects of PM2.5 and UFPs on the brain, and links to neurological diseases. However, the underlying mechanism has not yet been fully illustrated due to the variety of the study models, and different endpoints, etc. The adverse outcome pathway (AOP) framework is a pathway-based approach which could systematize mechanistic knowledge to assist health risk assessment of pollutants. Here, we constructed AOPs by collecting molecular mechanisms in PM-induced neurotoxicity assessments. We chose particulate matter (PM) as a stressor in the Comparative Toxicogenomics Database (CTD) and identified the critical toxicity pathways based on Ingenuity Pathway Analysis (IPA). We found 65 studies investigating the potential mechanisms linking PM2.5 and UFPs to neurotoxicity, which contained 2, 675 genes in all. IPA analysis showed that neuroinflammation signaling and glucocorticoid receptor signaling were the common toxicity pathways. The upstream regulator analysis (URA) of PM2.5 and UFPs demonstrated that the neuroinflammation signaling was the most initially triggered upstream event. Therefore, neuroinflammation was recognized as the MIE. Strikingly, there is a clear sequence of activation of downstream signaling pathways with UFPs, but not with PM2.5. Moreover, we found that inflammation response and homeostasis imbalance were key cellular events in PM2.5 and emphasized lipid metabolism and mitochondrial dysfunction, and blood-brain barrier (BBB) impairment in UFPs. Previous AOPs, which only focused on phenotypic changes in neurotoxicity upon PM exposure, we for the first time propose AOP framework in which PM2.5 and UFPs may activate pathway cascade reactions, resulting in adverse outcomes associated with neurotoxicity. Our toxicity pathway-based approach not advanced the risk assessment for PM-induced neurotoxicity but shine a spotlight on constructing AOP frameworks for new chemicals.

Long-term exposure to major constituents of fine particulate matter and neurodegenerative diseases: A population-based survey in the Pearl River Delta Region, China.

BACKGROUND: Exposure to PM2.5 has been linked to neurodegenerative diseases, with limited understanding of constituent-specific contributions. OBJECTIVES: To explore the associations between long-term exposure to PM2.5 constituents and neurodegenerative diseases. METHODS: We recruited 148,274 individuals aged ≥ 60 from four cities in the Pearl River Delta region, China (2020 to 2021). We calculated twenty-year average air pollutant concentrations (PM2.5 mass, black carbon (BC), organic matter (OM), ammonium (NH4+), nitrate (NO3-) and sulfate (SO42-)) at the individuals' home addresses. Neurodegenerative diseases were determined by self-reported doctor-diagnosed Alzheimer's disease (AD) and Parkinson's disease (PD). Generalized linear mixed models were employed to explore associations between pollutants and neurodegenerative disease prevalence. RESULTS: PM2.5 and all five constituents were significantly associated with a higher prevalence of AD and PD. The observed associations generally exhibited a non-linear pattern. For example, compared with the lowest quartile, higher quartiles of BC were associated with greater odds for AD prevalence (i.e., the adjusted odds ratios were 1.81; 95% CI, 1.45-2.27; 1.78; 95% CI, 1.37-2.32; and 1.99; 95% CI, 1.54-2.57 for the second, third, and fourth quartiles, respectively). CONCLUSIONS: Long-term exposure to PM2.5 and its constituents, particularly combustion-related BC, OM, and SO42-, was significantly associated with higher prevalence of AD and PD in Chinese individuals. ENVIRONMENTAL IMPLICATION: PM2.5 is a routinely regulated mixture of multiple hazardous constituents that can lead to diverse adverse health outcomes. However, current evidence on the specific contributions of PM2.5 constituents to health effects is scarce. This study firstly investigated the association between PM2.5 constituents and neurodegenerative diseases in the moderately to highly polluted Pearl River Delta region in China, and identified hazardous constituents within PM2.5 that have significant impacts. This study provides important implications for the development of targeted PM2.5 prevention and control policies to reduce specific hazardous PM2.5 constituents.

A phase II prospective randomized controlled trial of weekly paclitaxel combined with S-1 or fluorouracil for advanced gastric carcinoma / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To evaluate the efficacy and safety of weekly paclitaxel combined with S-1 or fluorouracil in the first line treatment of advanced gastric carcinoma.</p><p><b>METHODS</b>Two hundred and forty patients with untreated advanced gastric carcinoma were randomized into two arms, patients in the experimental arm were given paclitaxel and S-1, while those in the control arm received paclitaxel and fluorouracil. The regimen of experimental arm was paclitaxel 60 mg/m(2) by intravenous infusion, day 1, 8, 15; S-1 80 - 120 mg/day given by oral administration, day 1 - 14. The regimen of control arm was fluorouracil 500 mg/m(2) by intravenous infusion continuously, day 1 - 5; CF 20 mg/m(2) by intravenous infusion, day 1 - 5. The regimens in both arms were repeated every 28 days. The efficacy and safety of both arms were assessed.</p><p><b>RESULTS</b>Two hundred and twenty-eight patients were analyzed in the full analysis set, and 192 patients were analyzed in per-protocol set (experimental arm 100 patients, control arm 92 patients). The overall response rates of experimental and control arms were 50.0% and 28.3% (P = 0.002), and the disease control rates were 82.0% and 70.7% (P = 0.064), respectively. The primary endpoints of experimental arm were non-inferior to that of the control arm. The secondary endpoint of experimental arm in terms of median progression free survival was significantly better than that of control arm (5 months versus 4 months, P = 0.006). The experimental arm had a higher incidence of grade III-IV bone marrow suppression than the control arm, but the incidence of fever in both arms was not significantly different.</p><p><b>CONCLUSIONS</b>Oral administration of S-1 is an alternative option of venous infusional fluorouracil. Weekly paclitaxel combined with S-1 is a safe regimen and has a promising efficacy.</p>

Determination in oocytes of the reproductive modes for the brine shrimp Artemia parthenogenetica.

The brine shrimp, Artemia, reproduces either oviparously, producing encysted embryos (diapause cysts), or ovoviviparously, producing free-swimming nauplii. Environmental factors, such as photoperiod, have been applied to control the reproduction mode of Artemia, but when the determination of a reproductive mode occurs remains unknown. We analysed the differential gene expression between oocytes from oviparous and ovoviviparous Artemia reared under different photoperiods. A total of 692 qualified cDNA clones were obtained by subtractive hybridization, 327 of which matched GenBank® Nucleotide Sequence Database entries. Gene expressions of 44 cDNAs (representing 56 clones) were analysed in oocytes using real-time PCR. Among these genes, 11 (21 clones) were significantly (P<0.05) up-regulated and 7 (9 clones) down-regulated in Artemia oocytes that subsequently enter diapause. Remarkably, known diapause-related proteins such as ArHsp22 (Artemia heat-shock protein 22) and chitin-binding proteins are found to be already differentially expressed. Furthermore, RNAi (RNA interference) knockdown of a differentially expressed gene, polo-like kinase 1, in oocyte of ovoviviparous Artemia led to the production of white embryos rather than free-swimming nauplii. In summary, our results provide evidence at the molecular level that the reproductive mode of Artemia is already determined at the oocyte stage of their life cycle.