that autophagic cell death in the embryonic inner ear increased and apoptosis decreased with that the TUNEL-positive cell death remained unchanged after administration of CDDP to the pregnant mice. The purpose of this study was to elucidate the changes of gene and protein expressions which relate to the TUNEL-positive cell death after CDDP administration. METHOD: We used pregnant ICR mice for experiments on embryo. Between days 4-7 of pregnancy, ICR mice received CDDP (2.0 mg/kg/day) via intraperitoneal injection (CDDP group), and those of another group received same amount of isotonic sodium chloride solution (control group). On day 12 of pregnancy, we extracted embryonic inner ear and performed the real-time PCR to measure the gene expressions of beclin1 relative to autophagy and caspase3. The Western blot and immunohistochemistry were also performed to measure the expressions of beclin1 and caspase3 proteins. RESULTS: The real-time PCR showed both beclin1 and caspase3 gene expressions increased in the CDDP group as compared to Control group. Cleaved caspase3 protein was recognized in only apoptotic cells using immunohistochemis- try. In addition, the Western blot revealed the increase of beclin1 and caspase3 protein expressions, and the decrease of cleaved caspase3 in the CDDP group. CONCLUSION: Our ﬁndings suggest that the increase of beclin1 expression and the decrease of cleaved caspase3 pro- tein are associated with the increase of autophagic cell death and the decrease of apoptosis after CDDP administration. Prosthesis Diameter in Stapedotomy Roman Laske, MD (presenter); Christof Roosli, MD; Michail Chatzimichalis, MD; Jae Hoon Sim, PhD; Alex Huber, MD OBJECTIVE: 1) To analyze the inﬂuence of stapes prosthesis diameter on postoperative hearing results after stapedotomy in otosclerosis patients. 2) Be able to make an evidence based choice of right prosthesis diameter. METHOD: Meta-analysis and systematic review. A MED- LINE search was performed in April 2009, collecting literature since 1970 using the key words: stapedotomy or stapedectomy or otosclerosis or stapesplasty. Inclusion criteria (otosclerosis as diagnosis, clear description of technique and prosthesis size, calibrated stapedotomy, complete report of functional results) were then applied to select articles and patient groups for meta-analysis and statistical analyses. Data was used to per- form a meta-analysis (5 studies). 62 studies contributed a total of 9536 cases that were pooled according to the prosthesis diameter and the hearing results (Air-conduction, Air-Bone- gap, Closure of ABG) were analyzed by independent two- sample t-test (means) and chi square test (proportions). P  0.05 was considered to be statistically signiﬁcant. Additionally, studies that could not contribute direct data were reviewed and discussed - including experimental studies. RESULTS: Both, the meta-analysis and the comparison of the pooled groups showed signiﬁcant advantages for the 0.6 mm group when compared to the 0.4 mm group. CONCLUSION: A 0.6-mm diameter piston prosthesis achieves signiﬁcantly better results than a 0.4-mm prosthesis (Evidence Level 2a). Prussak‘s Space Assessed with a High Resolution Cone Beam CT Keiko Kashiba, MD (presenter); Masahiro Komori, MD, PhD; Naoaki Yanagihara, MD, PhD; Yasuyuki Hinohira, MD, PhD; Masafumi Sakagami, MD, PhD OBJECTIVE: We describe a method to obtain a front view image of the lateral oriﬁce of Prussak’s space (Ps oriﬁce or Pars ﬂaccida) and tympanic ring (Pars tensa) using a high resolution cone beam CT. Using this method, measurements of these structures in normal and diseased ears are made, and the importance of the method for exact diagnosis of scutum defect is emphasized. METHOD: Width and height of the Ps oriﬁce and vertical axes of the tympanic ring were measured on ten normal ears, 13 ears with chronic otitis media (COM) and 18 ears with acquired attic cholesteatoma. RESULTS: The size of the Ps oriﬁce is said to be normal if the height is less than 1.30mm and the width less than 2.63mm. In 100% of the ears with cholesteatoma, the height of the Ps oriﬁce was enlarged beyond the normal limit, and in 94.4% of the ears the width showed abnormal enlargement. The width and height in ears with cholesteatoma were signiﬁcantly larger than those in normal ears and in ears with COM (p0.01). As to the relationship between cholesteatoma staging and the size of Ps oriﬁce, no close relation was seen in the width. In contrast, the height was signiﬁcantly larger in the extensive cases (p0.05, ANOVA). No signiﬁcant difference was found between normal subjects and ears with COM. CONCLUSION: To determine the indications and appropriate method of reconstruction for tympanic scute, the CT images of Ps oriﬁce certainly provide valuable information. Release of Amino Acids From Vestibular Nuclei Christopher Frisch (presenter); Donald Godfrey, PhD; Yizhe Sun, MD, PhD OBJECTIVE: 1) Determine which neurotransmitter amino acids can be released from the vestibular nuclear complex (VNC) by depolarization with high potassium. 2) Estimate the amount of release related to neurotransmission by comparing release in normal and low calcium/high magnesium media. METHOD: Rat brain stems were isolated and sectioned into transverse slices. Tissue ventral to the VNC was cut away, and the slices were transferred into a chamber perfused with arti- ﬁcial cerebrospinal ﬂuid (ACSF). Four ACSF conditions were P245 Poster Presentations POSTERS