Investigation of bactericidal effect of a mid-infrared free electron laser on Escherichia coli.

The rapid increase in the number of bacteria that are resistant to many commonly used antimicrobial agents and their global spread have become a major problem worldwide. In particular, for periodontal disease, which is a localized infection, there is a growing need for treatment methods that do not primarily involve antimicrobial agents, and antimicrobial photodynamic therapy (aPDT) is attracting attention. In this study, the bactericidal effects of a mid-infrared free electron laser (MIR-FEL) on E. coli were investigated as a basic study to examine the applicability of MIR-FELs, which can selectively excite molecular vibrations due to their wavelength tunability, to aPDT. The optimal irradiation wavelengths to be examined in this study were determined from the infrared spectrum of the bacteria, which was obtained using Fourier transform infrared spectroscopy. Five irradiation wavelengths (6.62, 6.88, 7.14, 8.09 and 9.26 µm) were selected from the FT-IR spectrum, and we found that the bactericidal effects at a wavelength of 6.62 µm were markedly stronger than those observed at the other wavelengths. At this wavelength corresponding to the Amide II band, the bacterial survival rate decreased significantly as the irradiation time increased. On the contrary, irradiation of a neodymium-doped yttrium aluminum garnet (Nd: YAG) laser at 1.06 µm exhibited no distinct bactericidal effect. No morphological changes were observed after MIR-FEL irradiation, suggesting that a bacterial organelle molecule may be the target of MIR-FEL irradiation, but the exact target was not identified. Furthermore, the temperature change induced in the culture medium by the laser irradiation was ± 1.5 °C at room temperature. These results suggest that the bactericidal effects of MIR-FEL are derived from photochemical reactions involving infrared photons, since E. coli is usually killed by heating it to 75 °C for 1 min or longer.

Clinical outcomes of ventilation tube placement in children with cleft palate.

OBJECTIVE: The purpose of this study was to investigate the long-term clinical outcomes in children with cleft palate. METHODS: One hundred eight patients with cleft palate (CP) were investigated. Microscopic observation of the middle ears was performed periodically. If chronic otitis media with effusion (OME) was diagnosed at 1 year of age or later, ventilation tube (VT) placement was performed. The air-filled area of the mastoid air cells was checked on X-rays obtained at 1 and 5 years. The data from each measurement were tested statistically by the bootstrap method and Wilcoxon's rank-sum test. The clinical course from age 6 to the final examination (average 9.42 years) and the language development at 5 years were analyzed using data from the medical records of individual patients. RESULTS: VT placements were performed at 5 years of age or younger in 41 CP patients (82 ears, 38%). About 30% of patients treated by VT placement at 5 years of age or younger required myringotomy and/or VT re-placement at 6 years of age or over. Ninety-five percent of patients who had not been treated by VT insertion at 5 years of age or younger showed a favorable subsequent clinical course. Patients treated by VT insertion at 5 years of age or younger had significantly smaller mastoid air cell areas as measured at 5 years of age and also at 1 year of age. No significant difference in language development was observed between the CP patients that underwent /did not undergo VT placement. CONCLUSIONS: VT placement should be positively undertaken in CP children who have small mastoid air cell areas as measured at 1 year of age, because an unfavorable prognosis of OME is expected in such patients. It is considered that patients treated by VT placement at 5 years of age or younger should be carefully followed up for the development of OME even after 6 years of age. Thus, measurement of the mastoid air cell area at the age of 1 year is useful for determining the therapeutic program.

Palatoplasty and growth of the temporal bone mastoid air cells.

OBJECTIVES: The present study was undertaken to analyze the relationship between the method used for manipulation of the levator veli palatini muscle and the area of the mastoid air cells in patients with cleft palate. DESIGN: Retrospective study. PATIENTS: The subjects were 50 patients seen for surgical treatment of cleft palate. INTERVENTIONS: Palatoplasty was carried out using the mucosal flap method in 25 patients and the mucoperiosteal flap method in 25 patients. In the mucosal flap method, the levator veli palatini muscle was overlapped and sutured, followed by posterior movement of the muscle bundle (the posterior relocation group). In the mucoperiosteal flap method (the control group), the mucoperiosteal flap was pushed back, followed by end-to-end suturing of the muscle. The area of the mastoid air cells was measured on X-rays when patients were 5 years old. RESULTS: The mastoid air cell area did not differ significantly between the posterior relocation group (mean, 5.00 cm(2); range, 1.66 to 19.7 cm(2)) and the control group (mean, 5.3 cm(2); range, 2.29 to 15.9 cm(2)). CONCLUSION: No significant growth of mastoid air cells was noted following posterior relocation of the levator veli palatini muscle. Thus, in cases of cleft palate in which significant growth of mastoid air cells is not expected following reconstruction of the levator veli palatini muscle, the results confirm the view that tympanic ventilation tube insertion is the most suitable method for the treatment of otitis media.

[Combination steroid and hyperbaric oxygenation therapy for sudden idiopathic sensorineural hearing loss].

We retrospectively evaluated the efficacy of combination therapy with steroid and hyperbaric oxygenation for sudden idiopathic sensorineural hearing loss (SISNHL). Patients (n: 109; 111 ears) visited our clinic within 14 days from onset before receiving treatment between January 1999 and March 2003. Hearing loss was assessed based on criteria prepared by the Ministry of Health and Welfare Acute Severe Hearing Loss Study Group. Patients were distributed into Group I-95 patients who started treatment within 7 days from onset-, and Group II-14 patients who started treatment within 8-14 days from onset. We evaluated the outcome of therapy using grading established by The Research Committee on Acute Profound Deafness, Ministry of Health and Welfare, Japan. The complete recovery of hearing was worse in patients with severe hearing loss. It was 4.8% in grade 4a, 18.2% in grade 3a, 25% in grade 2a, 20.0% in grade 4b, 38.5% in grade 3b, and 66.7% in grade 2b. We studied the relationship between type of hearing loss and recovery after treatment. The complete recovery of hearing was most favorable in patients with low tone hearing loss, followed by those with middle tone hearing loss and those with horizontal hearing loss. These findings indicate that the type of hearing loss was the most significant determinant of SISNHL prognosis and course. Twenty patients with acute stage SISNHL had diabetes mellitus. The recovery of hearing was almost the same in those with and without diabetes mellitus. Recovery was complete in 32.4%, Niarked in 32.4%, and slight in 21.6%. In 13.5%, no change was observed. Our results and data from previous reports, involving more than 70 Japanese patients treated with steroids alone, suggest that combination therapy with steroid and hyperbaric oxygenation is effective for SISNHL.