Ecotoxicity and environmental safety assessment of two-dimensional niobium carbides (MXenes).

Two-dimensional (2D) MXenes have gained great interest in water treatment, biomedical, and environmental applications. The antimicrobial activity and cell toxicity of several MXenes including Nb4C3Tx and Nb2CTx have already been explored. However, potential side effects related to Nb-MXene toxicity, especially on aquatic pneuma, have rarely been studied. Using zebrafish embryos, we investigated and compared the potential acute toxicity between two forms of Nb-MXene: the multilayer (ML-Nb4C3Tx, ML-Nb2CTx) and the delaminated (DL-Nb2CTx, and DL-Nb4C3Tx) Nb-MXene. The LC50 of ML-Nb4C3Tx, ML-Nb2CTx, DL-Nb2CTx, and DL-Nb4C3Tx were estimated to be 220, 215, 225, and 128 mg/L, respectively. Although DL-Nb2CTx, and DL-Nb4C3Tx derivatives have similar sizes, DL-Nb4C3Tx not only shows the higher mortality (LC50 = 128 mg/L Vs 225 mg/L), but also the highest teratogenic effect (NOEC = 100 mg/L Vs 200 mg/L). LDH release assay suggested more cell membrane damage and a higher superoxide anion production in DL-Nb4C3Tx than DL-Nb2CTx,. Interestingly, both DL-Nb-MXene nanosheets showed insignificant cardiac, hepatic, or behavioral toxic effects compared to the negative control. Embryos treated with the NOEC of DL-Nb2CTx presented hyperlocomotion, while embryos treated with the NOEC of DL-Nb4C3Tx presented hyperlocomotion, suggesting developmental neurotoxic effect and muscle impairment induced by both DL-Nb-MXene. According to the Fish and Wildlife Service (FSW) Acute Toxicity Rating Scale, all tested Nb-MXene nanosheets were classified as "Practically not toxic". However, DL-Nb4C3Tx should be treated with caution as it might cause a neurotoxic effect on fauna when it ends up in wastewater in high concentrations.

Transcriptome Profile Identifies Actin as an Essential Regulator of Cardiac Myosin Binding Protein C3 Hypertrophic Cardiomyopathy in a Zebrafish Model.

Variants in cardiac myosin-binding protein C (cMyBP-C) are the leading cause of inherited hypertrophic cardiomyopathy (HCM), demonstrating the key role that cMyBP-C plays in the heart's contractile machinery. To investigate the c-MYBPC3 HCM-related cardiac impairment, we generated a zebrafish mypbc3-knockout model. These knockout zebrafish displayed significant morphological heart alterations related to a significant decrease in ventricular and atrial diameters at systolic and diastolic states at the larval stages. Immunofluorescence staining revealed significant hyperplasia in the mutant's total cardiac and ventricular cardiomyocytes. Although cardiac contractility was similar to the wild-type control, the ejection fraction was significantly increased in the mypbc3 mutants. At later stages of larval development, the mutants demonstrated an early cardiac phenotype of myocardium remodeling, concurrent cardiomyocyte hyperplasia, and increased ejection fraction as critical processes in HCM initiation to counteract the increased ventricular myocardial wall stress. The examination of zebrafish adults showed a thickened ventricular cardiac wall with reduced heart rate, swimming speed, and endurance ability in both the mypbc3 heterozygous and homozygous groups. Furthermore, heart transcriptome profiling showed a significant downregulation of the actin-filament-based process, indicating an impaired actin cytoskeleton organization as the main dysregulating factor associated with the early ventricular cardiac hypertrophy in the zebrafish mypbc3 HCM model.

Factors Associated with Mental Health Outcomes: Results from a Tertiary Referral Hospital in Lebanon during the COVID-19 Pandemic.

Coronavirus Disease (COVID-19) has caused global mental health impacts, and healthcare workers (HCWs) face an increased risk of exposure to the disease when compared to the general population. This study aimed to assess factors associated with mental health among Lebanese HCWs six months after the start of the COVID-19 pandemic. A cross-sectional study was conducted among HCWs at a tertiary hospital, in Lebanon between June and July 2020. The survey included data on demographics, exposure to COVID-19, preparedness to COVID-19 outbreak, risk perceptions of COVID-19, and mental health dimensions. Chi-squared and Fisher's exact tests were used to understand the association among these variables. One hundred and ninety-three of 1,600 Lebanese HCWs participated. More than 80% reported high preparedness levels towards the COVID-19 outbreak, 69% believed that their job was putting them at risk, and 70% altruistically accepted these risks. Anxiety and depression symptomatology were present in 24% and 23% of HCWs; who were more likely to feel more stress at work (83% vs 60%; p = 0.004; 82% vs 61%; p = 0.01, respectively), feel afraid of falling ill (72% vs 55%; p = 0.03; 77% vs 54%; p = 0.01, respectively), fear death (21% vs 7%; p = 0.01; 25% vs 6%; p ≤ 0.001, respectively), and believed that people avoided their families (39% vs 21%; p = 0.01; 35% vs 65%; p = 0.02, respectively). HCWs who reported signs of depression were less likely to altruistically accept the risks of caring for COVID-19 patients, compared to those who did not (57% vs 74%; p = 0.03). This study aimed to detect factors associated with mental health among Lebanese HCWs during the COVID-19 pandemic. Findings suggested that altruistic acceptance of COVID-19 risks is higher among HCWs with positive exposure history to COVID-19 and those with less depressive symptomatology.