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Epithelial Function and Airway Responsiveness
Published in Alastair G. Stewart, AIRWAY WALL REMODELLING in ASTHMA, 2020
Roy G. Goldie, Janet M. H. Preuss
Neuroendocrine cells are in low density, scattered throughout the respiratory tract, with increasing numbers detected with decreasing airway size.16Importantly, pulmonary neuroendocrine cells (PNEC) contain a number of substances with potentially important biologic activities in the airways. For example, PNECs contain 5-hydroxytryptamine, bombesin, calcitonin gene-related peptide, somatostatin, and endothelin, as well as gastrin-releasing peptide, katacalcin, and calcitonin.16 Rather than secreting their contents into the airway lumen, mediator release from these cells is polarised such that products are directed towards cells beneath the epithelial basement membrane, including nerves, blood vessels, and airway smooth muscle.17–19 Neuroepithelial bodies are clusters of neuroendocrine cells and are often seen in close apposition to nerves. In such cases, they may act as intrapulmonary chemoreceptors.15,20 It is also noteworthy that the numbers of PNECs increase in various respiratory disorders, including cystic fibrosis, emphysema, chronic bronchitis, bronchopulmonary dysplasia, and asthma.16
An Introduction to Risk Assessment with a Nod to History
Published in Ted W. Simon, Environmental Risk Assessment, 2019
Step 3, the environmental hazard assessment, determines the environmental concentration thought to have no impact, the “predicted no-effect concentration” (PNEC). PNECs are developed for water and sediment in marine and freshwater environments. If necessary, PNECs for air or food chain exposure may also be developed.
Etiology of Neonatal Respiratory Distress Syndrome and the Assessment of Lung Maturity
Published in Jacques R. Bourbon, Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
Michel Dehan, Jeanne Francoual, Marie Claire Imbert, Benoit Denizot
Immunochemical studies have been made on pulmonary neuroendocrine epithelial cells (PNEC)44 and alveolar cells.45 The PNEC are a distinct population of granulated cells containing bioactive molecules such as bombesin, serotonin, and vasopeptides (see Chapter 7). These cells, located near both pulmonary vessels and nerves, are numerous in the neonatal period. They are identified with rabbit antibombesin serum. They may be chemoreceptors exerting control over pulmonary vascular tone and airway tone. In the early stage of HMD, there is a marked decrease of bombesin immunoreactive cells.44
Azithromycin effects on the European sea bass (Dicentrarchus labrax) early life stages following acute and chronic exposure: Laboratory bioassays
Published in Drug and Chemical Toxicology, 2022
Lazhar Mhadhbi, Tahani El Ayari, Meriam Tir, Dorra Kadri
European sea bass (Discentrarchus labrax) eggs (N = 1400) were obtained from the Sud Aquaculture Tunisia (SAT). Azithromycin (98% purity) was obtained from sigma Aldrich through the central pharmacy in Tunisia. Fifteen eggs from D. labrax were placed at aquaria containing 1 L of seawater (salinity 34 ‰). During the experimental exposure to AZI eggs were maintained in a dark room at a temperature of 14 ± 1 °C. Acute toxicology test was conducted according to the OECD guideline No. 203 (OECD 2019). Azithromycin effects on D. labrax early life stages were investigated using six increasing concentrations (0.625, 1.25, 2.5, 5, 10, 20 mg/l) and a control group receiving only seawater. Four replicates were considered for each concentration. Tests were performed during 96 h, every 24 h, number of dead eggs, and embryos as well as water temperature, pH, and oxygen saturation were monitored. Concentrations of AZI have been chosen based on the recommendation of the OECD guideline for the testing of chemicals (OECD 2019). We also take into account the value of the predicted no-effect concentration (PNEC) calculated for AZI 0.015 µg/l and 0.019 µg/l (Harrabi et al. 2018; Verlicchi et al. 2012). Furthermore, information about AZI toxicity on tilapia, Oreochromis niloticus were considered (Shiogiri et al. 2017).
Human hazard potential of nanocellulose: quantitative insights from the literature
Published in Nanotoxicology, 2020
Natasha Stoudmann, Mélanie Schmutz, Cordula Hirsch, Bernd Nowack, Claudia Som
In addition to considering all different cell lines in in vitro tests without any distinction, we looked at toxicity relating to specific cell lines used in the context of cytotoxicity to identify whether any patterns emerged. Different cell lines used could explain differences in study results, as various cell lines are more or less sensitive. We identified 16 cell lines having been tested against CNC, and 13 for CNF (Figure 6), from 22 studies. Data from 50 CNC and 45 CNF materials are shown. In the Supplementary material further explanation on the cell lines is given. To visualize the data, we employed a similar method as the probabilistic species sensitivity distribution (PSSD) used in ecotoxicology (Hauser, Li, and Nowack 2019; Wigger et al. 2020). PSSD curves represent the cumulative sensitivity of species to a substance within an environmental compartment. A Predicted No Effect Concentration (PNEC) is then derived from the HC5 (hazardous concentration for less than 5% of species) (European Chemicals Agency 2008). In our case, we replaced the species by cell lines (Bilal et al. 2019), to create a probabilistic cell sensitivity distribution (PCSD). Our goal was purely data visualization, and we did not extract a PNEC value from the resulting curve.
Material-specific properties applied to an environmental risk assessment of engineered nanomaterials – implications on grouping and read-across concepts
Published in Nanotoxicology, 2019
The PNEC of a substance is the estimated concentration at which no adverse effect is expected. Basically, two main approaches currently are regulatory compliant. First, deterministic PNECs can be derived by dividing the ecotoxicological value for one (relevant) species by an assessment factor (AF) considering the uncertainty associated to the data. Second, the SSD approach takes into account several species at once by using the lowest ecotoxicological value or geometric mean per species. A cumulative SSD curve is fitted to this dataset based on a predefined distribution such as log-normal, log-logistic or others, for instance (ECHA 2008). The final PNEC value is derived from the SSD curve by extracting the hazardous concentration (HC5) at which five percent of the biological community is threatened (i.e. 95% of the species are protected) and an additional AF of 1-5 has to be applied depending on the dataset quality (ECHA 2008).