Streptomycin ototoxicity in rat cochlear organotypic cultures

Nicotine induced ototoxicity in rat cochlear organotypic cultures

Epidemiological evidence has shown that smoking is associated with an increased risk of hearing loss. However, the underlying mechanisms regarding the impact of nicotine on the cochlea remain unclear. This study aimed to investigate the cytotoxic effects of nicotine on cochlear cells using cultured cochlear basilar membranes. Cochlear basilar membranes were isolated from newborn rats, cultured, and treated with 1–100 ng/mL nicotine for 48 h. Cuticular plates and stereocilia bundle staining were used to evaluate hair cell (HC) loss. Spiral ganglion neuron and acoustic nerve fiber staining were assessed to evaluate cochlear neural injury. Scanning electron microscopy and transmission electron microscopy imaging were employed to examine cochlear ultrastructural changes. Our results showed that compared to spiral ganglia and nerve fibers, HCs are more susceptible to nicotine-induced toxicity. HC loss was more severe in the basal turn than in the middle and apical turns, while nerve fibers and spiral ganglion cells were morphologically maintained. Ultrastructural changes revealed disordered and damaged stereocilia, swelling and decreased mitochondrial density, swelling, and degranulation of the endoplasmic reticulum. Our results suggest that nicotine causes HCs’ degeneration and loss and may have implications for smoking-related hearing loss.

In Vitro Evaluation of the Antimicrobial Ability and Cytotoxicity on Two Melanoma Cell Lines of a Benzylamide Derivative of Maslinic Acid

Maslinic acid is a pentacyclic triterpene extracted from olives that has been systematically reported to exert several therapeutic effects, such as antitumoral, antidiabetic, antioxidant, anti-inflammatory, antiparasitic, and antiviral properties. Recently, new derivatives of maslinic acid have been obtained and expanded the spectrum of biological activities and improved the existing ones. The present study was meant to perform the in vitro assessment of the (i) cytotoxic effects of a benzylamide derivative of maslinic acid ("EM2") (benzyl (2α, 3β) 2,3-diacetoxy-olean-12-en-28-amide) on B164A5 murine melanoma and A375 human malignant melanoma cell lines and the (ii) antimicrobial activity of the compound on several bacterial strains, respectively. We obtained a dose-dependent cytotoxic effect of EM2 that was particularly relevant to the murine cell line. As on the antibacterial activity, EM2 was tested on 10 bacterial strains Bacillus cereus, Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, Enterococcus faecalis, Escherichia coli, Yersinia enterocolitica, Klebsiella pneumoniae, Proteus mirabilis, and Pseudomonas aeruginosa and one fungus Candida albicans. A significant antimicrobial effect was recorded for Streptococcus pyogenes and Staphylococcus aureus.