Hexanal, 2-heptenal, and nonanal were identified as relevant reaction products formed in the course of the lipid peroxidation of heated peanut oil. For the identification of potential amino acid side chain adducts, kinetic studies between N(α)-benzoylglycyl-l-lysine as a model for protein-bound lysine and trans-2-heptenal were performed, showing a strong decrease of the lysine-derivative whereupon the loss of trans-2-heptenal was moderate. Following acid hydrolysis of the incubation mixture of N(α)-acetyl-l-lysine and trans-2-heptenal, two UV-active major lipation products were observed, isolated and identified as isomeric pyridinium-derivatives, namely (Z)- and (E)-1-(5-amino-5-carboxypentyl)-4-butyl-3-(pent-1-en-1-yl)pyridin-1-ium (cis- and trans-BPP-lysine). After heating of a native peanut protein extract with trans-2-heptenal, both derivatives were quantitated by LC-ESI-MS/MS after acid hydrolysis and the modification of lysine was measured by amino acid analysis. At low, "food-relevant", concentrations of trans-2-heptenal, up to 80% of the lysine modification could be explained by the formation of cis- and trans-BPP-lysine, showing that these two lipation derivatives represent good markers for a protein modification by the lipid peroxidation product trans-2-heptenal.

An endoscopic optical coherence tomography (OCT) system with a wide field-of-view of 8 mm is presented, which combines the image capability of endoscopic imaging at the middle ear with the advantages of functional OCT imaging, allowing a morphological and functional assessment of the human tympanic membrane. The endoscopic tube has a diameter of 3.5 mm and contains gradient-index optics for simultaneous forward-viewing OCT and video endoscopy. The endoscope allows the three-dimensional visualization of nearly the entire tympanic membrane. In addition, the oscillation of the tympanic membrane is measured spatially resolved and in the frequency range between 500 Hz and 5 kHz with 125 Hz resolution, which is realized by phase-resolved Doppler OCT imaging during acoustical excitation with chirp signals. The applicability of the OCT system is demonstrated in vivo. Due to the fast image acquisition, structural and functional measurements are only slightly affected by motion artifacts.

Objective: After tympanoplasty, it is often challenging to differentiate between different causes of a remaining air bone gap (ABG). Optical coherence tomography (OCT) offers a new approach for combined morphologic and functional measurements of the tympanic membrane and adjacent parts of the middle ear. Thus, it provides valuable diagnostic information in patients with a reduced sound transfer after middle ear surgery. Patient and intervention: A patient with history of tympanoplasty and a persistent ABG was investigated with endoscopic OCT before revision surgery. Main Outcome Measures: The oscillation behavior and the thickness of the reconstructed tympanic membrane was determined. The oscillation amplitudes of the inserted prosthesis were compared to a finite element model simulation and to the clinical findings and the audiometric data of the patient. Results: OCT measurements showed a reduced oscillation amplitude of the prosthesis while revealing an aerated middle ear and good coupling of the prosthesis. Transfer loss measured by OCT showed a similar progression as the ABG measured by pure-tone audiometry with a mean divergence of 4.45 dB. Conclusion: Endoscopic OCT is a promising tool for the evaluation of tympanoplasty outcome. It supports established otologic diagnostics and can help differentiating between different causes of conductional hearing loss.

Abstract:In this ex vivo feasibility study, endoscopic structural and functional optical coherence tomography (OCT) imaging with a field of view of 8 mm is presented allowing the inspection of nearly the entire tympanic membrane through the ear canal. The endoscope utilizes a gradient index optics for simultaneous OCT and video endoscopy. Additionally, Doppler-OCT allows the measurement of the tympanic membrane oscillation. Due to the fast image acquisition, only minor motion artifacts have been observed, which don't affect the image quality. In conclusion, endoscopic OCT is considered as a promising tool for the comprehensive examination of the human middle ear.