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A study was conducted to investigate the structure and quadratic vibrational force field of methyldifluoramine (CH3NF2) molecules. Results of the study found that the phenomenon of progressive bond shortening with increasing fluorine substitution is evident, with values in the series NF3 - MeNF2 - Me2NF being 0.035 and 0.041 A, respectively. Similar changes are seen in the series with hydrogen replacing the methyl groups: for NF3 - HNF2 - H2NF they are 0.029 and 0.033 A, respectively. Other results are discussed.

A new series of perfluoroazidoazomethines and perfluoroalkylcarbodiimides derived from the photolytic reaction of SF5Cl with corresponding olefins was subjected to spectroscopic and gas electron diffraction analyses. The compounds contained the -SF5 unit which promoted high dielectric interactions. Additional reactiviy studies were performed to determine the behavior of the newly formed compounds in different processes.

The photolysis of a mixture of CF2I2 and NO produced difluorodinitrosomethane, with products dependent on radiation time. Upon photolysis of about eight hours, hexafluorodinitrosopropane was formed at approximately 20% yield with remaining traces of ONCF2NO. The synthesis of O2NC6H4=NCF2N=NC6H4NO2 was done for confirmation of the p-O2NC6H4NH2 structure by mass, F and H NMR, and IR spectra.

Our previous studies showed that pretreatment with corticosteroids, which inhibits release of arachidonic acid (precursor of prostaglandins and leukotrienes), partially prevented salicylate-induced hearing loss in vivo. The purpose of this study was to determine the effect of pretreatment with corticosteroid (dexamethasone sodium phosphate) on isolated cochlear outer hair cells (OHCs) exposed to salicylate in vitro. Isolated OHCs from the chinchilla cochlea were exposed lo salicylate with or without pretreatment with dexamethasone. Images were stored and analyzed on the image program. The OHCs exposed to saticylate demonstrated a significant shortening in cell length. The OHCs exposed lo salicylate after pretreatment with dexamethasone exhibited no significant change in cell length. We conclude that corticosteroid treatment of isolated OHCs is effective in blocking the morphological changes induced by salicylate. This study gives additional evidence that salicylate ototoxicity is mediated by alteration in the levels of arachidonic acid metabolites. [ABSTRACT FROM AUTHOR]

Objective --To assess the ototoxicity of commercially available Gentacidin® and TobraDex® ear drops with and without liver extract activation using isolated cochlear outer hair cells (OHCs). Material and Methods --OHCs from adult chinchilla cochleae were exposed to standard bathing solution (SBS), liver extract alone and Gentacidin and TobraDex ear drops with and without liver extract. All experiments were performed at an osmolality of 305±5 mOsm, at room temperature and for up to 60 min. OHC images were recorded using an inverted microscope and analyzed electronically. Time to cell death and changes in cell length were measured. Results --The time to cell death and the percent change in cell length were significantly shorter in the Gentacidin+liver extract group than in the Gentacidin alone group ( p <0.05). The TobraDex+liver extract group showed a significantly decreased time to cell death compared to the SBS control group ( p <0.05). There were no significant differences in cell length or time to cell death between the TobraDex+liver extract group and the TobraDex alone group ( p >0.05). Conclusion --This study suggests that the cytotoxicity of aminoglycoside ear drops to isolated OHCs in vitro requires activation. [ABSTRACT FROM AUTHOR]

Otic drops are commonly used not only for otitis externa but also for otorrhea in the presence of tympanostomy tube or tympanic membrane perforation. Many studies have demonstrated the ototoxicity of common otic preparations such as Cortisporin® otic drops. Recent studies have suggested the use of fluoroquinolone antibiotic drops as an alternative owing to their excellent antimicrobial coverage and no ototoxic effect. The purpose of this study was to assess the relative ototoxicity of four common otic preparations by direct exposure to isolated cochlear outer hair cells (OHCs). OHCs from adult chinchilla cochlea were exposed to standard bathing solution (control), Cortisporin, Cipro HC®, Ciloxan®, and Floxin®. The cells were observed using an inverted microscope, and the images recorded in digital still-frame and video, and analyzed on the Image Pro-Plus® 3.0 program. As measured by time to cell death and change in morphology of OHCs, Cortisporin was most toxic to OHCs. Among the fluoroquinolone drops, Floxin was more toxic than Ciloxan or Cipro HC. [ABSTRACT FROM AUTHOR]