The mechanism of the shifting of the bioluminescence spectrum from the reaction of bacterial luci... more The mechanism of the shifting of the bioluminescence spectrum from the reaction of bacterial luciferase by lumazine protein is investigated by methods of fluorescence dynamics. A metastable intermediate is produced on reaction of Vibrio harveyi luciferase with FMNH2 and O2. It has an absorption maximum at 374 nm and a rotational correlation time (phi) derived from the decay of its fluorescence (maximum 500 nm) anisotropy of 90 ns (2 degrees C). Lumazine protein from Photobacterium phosphoreum has an absorption maximum at 417 nm and a fluorescence maximum at 475 nm. Lumazine protein forms a protein-protein complex with luciferase, and the complex has a phi of approximately 100 ns. A mixture of lumazine protein and the intermediate would be expected to have an average correlation time (phi av) around 100 ns, but instead, the result is anomalous. The phi av is much lower and is also wavelength dependent. For excitation at 375 nm, which is mainly absorbed in the flavin chromophore of the intermediate, phi av = 25 ns, but at 415 nm, mainly absorbed by the lumazine derivative ligand of lumazine protein, phi av approximately 50 ns. It is proposed that protein-protein complexation occurs between lumazine protein and the luciferase intermediate and that in this complex energy transfer from the flavin to the lumazine is the predominant channel of anisotropy loss. A distance of 20 A between the donor and acceptor is calculated. In the bioluminescence reaction of intermediate with tetradecanal, a fluorescent transient species is produced which is the bioluminescence emitter.(ABSTRACT TRUNCATED AT 250 WORDS)
Background Saline nasal irrigation has become an important aspect of post-operative care followin... more Background Saline nasal irrigation has become an important aspect of post-operative care following endoscopic sinus surgery. The objective of this study was to identify the risks of contamination of both the nasal irrigation bottle and fluid following endoscopic sinus surgery. Methods This was a prospective study of consecutive patients undergoing endoscopic sinus surgery for chronic sinusitis. All patients were given nasal irrigation bottles with detailed cleaning instructions preoperatively. Nasal irrigation bottles were collected and cultured at 1 and 2 weeks postoperatively. During the same visit, 5-ml of sterile normal saline was mixed into the irrigation bottle and then cultured separately. Results A total of 20 patients agreed to participate in the study. At 1 week postoperatively, 50% of the bottles had positive cultures with 40% of the irrigation samples testing positive for bacteria. At two weeks, the contamination in the irrigation bottle and fluid decreased to 26.7% and ...
International journal of pediatric otorhinolaryngology, 2012
Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been ... more Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been associated with facial nerve and vestibular end-organ stimulation suggesting potential for extra-cochlear stimulation. The objectives of this study were to investigate the potential relationship between cochlear implantation and seizure activity in the pediatric implant population. Local Research Ethics Board approval was obtained. The Hospital for Sick Children's Cochlear Implant Database from 1998 to 2011 was retrospectively reviewed. Based on a multidisciplinary team, patients who received a diagnosis of seizure disorder or had been investigated for seizure-like activity were identified and reviewed. Fifteen children from a group of 816 pediatric cochlear implant users were identified as having suspected seizure-like activity. Eventually 10 children were found to have seizures based on an evaluation by a pediatric neurologist and an electroencephalogram. Of these 10, only 3 childr...
The mechanism of the shifting of the bioluminescence spectrum from the reaction of bacterial luci... more The mechanism of the shifting of the bioluminescence spectrum from the reaction of bacterial luciferase by lumazine protein is investigated by methods of fluorescence dynamics. A metastable intermediate is produced on reaction of Vibrio harveyi luciferase with FMNH2 and O2. It has an absorption maximum at 374 nm and a rotational correlation time (phi) derived from the decay of its fluorescence (maximum 500 nm) anisotropy of 90 ns (2 degrees C). Lumazine protein from Photobacterium phosphoreum has an absorption maximum at 417 nm and a fluorescence maximum at 475 nm. Lumazine protein forms a protein-protein complex with luciferase, and the complex has a phi of approximately 100 ns. A mixture of lumazine protein and the intermediate would be expected to have an average correlation time (phi av) around 100 ns, but instead, the result is anomalous. The phi av is much lower and is also wavelength dependent. For excitation at 375 nm, which is mainly absorbed in the flavin chromophore of the intermediate, phi av = 25 ns, but at 415 nm, mainly absorbed by the lumazine derivative ligand of lumazine protein, phi av approximately 50 ns. It is proposed that protein-protein complexation occurs between lumazine protein and the luciferase intermediate and that in this complex energy transfer from the flavin to the lumazine is the predominant channel of anisotropy loss. A distance of 20 A between the donor and acceptor is calculated. In the bioluminescence reaction of intermediate with tetradecanal, a fluorescent transient species is produced which is the bioluminescence emitter.(ABSTRACT TRUNCATED AT 250 WORDS)
Background Saline nasal irrigation has become an important aspect of post-operative care followin... more Background Saline nasal irrigation has become an important aspect of post-operative care following endoscopic sinus surgery. The objective of this study was to identify the risks of contamination of both the nasal irrigation bottle and fluid following endoscopic sinus surgery. Methods This was a prospective study of consecutive patients undergoing endoscopic sinus surgery for chronic sinusitis. All patients were given nasal irrigation bottles with detailed cleaning instructions preoperatively. Nasal irrigation bottles were collected and cultured at 1 and 2 weeks postoperatively. During the same visit, 5-ml of sterile normal saline was mixed into the irrigation bottle and then cultured separately. Results A total of 20 patients agreed to participate in the study. At 1 week postoperatively, 50% of the bottles had positive cultures with 40% of the irrigation samples testing positive for bacteria. At two weeks, the contamination in the irrigation bottle and fluid decreased to 26.7% and ...
International journal of pediatric otorhinolaryngology, 2012
Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been ... more Cochlear implantation is a successful method of auditory rehabilitation. This procedure has been associated with facial nerve and vestibular end-organ stimulation suggesting potential for extra-cochlear stimulation. The objectives of this study were to investigate the potential relationship between cochlear implantation and seizure activity in the pediatric implant population. Local Research Ethics Board approval was obtained. The Hospital for Sick Children's Cochlear Implant Database from 1998 to 2011 was retrospectively reviewed. Based on a multidisciplinary team, patients who received a diagnosis of seizure disorder or had been investigated for seizure-like activity were identified and reviewed. Fifteen children from a group of 816 pediatric cochlear implant users were identified as having suspected seizure-like activity. Eventually 10 children were found to have seizures based on an evaluation by a pediatric neurologist and an electroencephalogram. Of these 10, only 3 childr...
Uploads
Papers by John Lee