Novel method of intraoperative ocular movement monitoring using a piezoelectric device: experimental study of ocular motor nerve activating piezoelectric potentials (OMNAPP) and clinical application for skull base surgeries.

Intraoperative monitoring systems that utilize various evoked potentials for the detection and/or preservation of cranial nerves have become increasingly common due to recent technical and commercial developments, particularly during skull base surgeries. We established a novel system for the intraoperative monitoring of the extraocular motor nerves (eOMNs) using a piezoelectric device capable of detecting imperceptible vibrations induced by ocular movement, with sensors placed on the eyelids alone. We first evaluated the efficacy and reliability of this device for the intraoperative monitoring of eOMNs in two Beagle dogs. Based on the results, we then determined the appropriate stimulation parameters for use in human surgical cases involving removal of various skull base tumors. Animal experiments revealed that a 0.4 mA monopolar electrical stimulation was required to elicit significant responses and that these responses were not inferior to those obtained via the electrooculogram/electromyogram. Significant responses were also detected in preliminary clinical investigations in human patients, following both direct and indirect monopolar electrical stimulation of the oculomotor and abducens nerves, although obtaining responses from the trochlear nerve was difficult. Intraoperative monitoring using a piezoelectric device provides a simple and reliable method for detecting eOMNs, especially the oculomotor and abducens nerves. This monitoring system can be adapted to various surgeries for skull base tumor.

Purification, amino acid sequence, and cDNA cloning of trypsin inhibitors from onion (Allium cepa L.) bulbs.

Three protease inhibitors (OTI-1-3) have been purified from onion (Allium cepa L.) bulbs. Molecular masses of these inhibitors were found to be 7,370.2, 7,472.2, and 7,642.6 Da by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), respectively. Based on amino acid composition and N-terminal sequence, OTI-1 and -2 are the N-terminal truncated proteins of OTI-3. All the inhibitors are stable to heat and extreme pH. OTI-3 inhibited trypsin, chymotrypsin, and plasmin with dissociation constants of 1.3 x 10(-9) M, 2.3 x 10(-7) M, and 3.1 x 10(-7) M, respectively. The complete amino acid sequence of OTI-3 showed a significant homology to Bowman-Birk family inhibitors, and the first reactive site (P1) was found to be Arg17 by limited proteolysis by trypsin. The second reactive site (P1) was estimated to be Leu46, that may inhibit chymotrypsin. OTI-3 lacks an S-S bond near the second reactive site, resulting in a low affinity for the enzyme. The sequence of OTI-3 was also ascertained by the nucleotide sequence of a cDNA clone encoding a 101-residue precursor of the onion inhibitor.