Computed tomographic features of clinical and subclinical middle ear disease in domestic rabbits (Oryctolagus cuniculus): 88 cases (2007-2014).

OBJECTIVE: To describe and compare CT abnormalities of the middle ear in rabbits (Oryctolagus cuniculus) that had clinical or subclinical middle ear disease and to determine the prevalence of otitis media and evaluate the role of predisposing factors for otitis media in that species. DESIGN: Retrospective case series. ANIMALS: 88 domestic rabbits. PROCEDURES: Medical records for rabbits that underwent CT of the head in June 2007 through February 2014 were searched and classified on the basis of reason for head CT (i.e., ear-related disease vs non-ear-related disease). The ears, upper respiratory tract, teeth, and other important structures of each rabbit's head were evaluated. Follow-up information was obtained for rabbits with CT abnormalities of the middle ear without clinical signs (i.e., subclinical disease). RESULTS: 12 of 21 (57%) rabbits with clinical signs of ear disease and 18 of 67 (27%) rabbits without clinical signs of ear disease had CT abnormalities of the middle ear. In CT images, all affected ears had soft tissue-attenuating material within the tympanic bulla. Tympanic bulla lysis was associated with clinical middle ear disease. Most (12/18) rabbits with subclinical middle ear disease remained subclinical after CT examination. Middle ear CT-detected changes and lop-ear conformation or otitis externa were strongly correlated; middle ear disease and upper respiratory tract disease were not correlated. CONCLUSIONS AND CLINICAL RELEVANCE: Data suggested that subclinical otitis media frequently affects rabbits, and those with bulla lysis should be closely monitored. Lop-eared rabbits and rabbits with otitis externa had a higher risk of developing otitis media.

The Xenopus Xmus101 protein is required for the recruitment of Cdc45 to origins of DNA replication.

The initiation of eukaryotic DNA replication involves origin recruitment and activation of the MCM2-7 complex, the putative replicative helicase. Mini-chromosome maintenance (MCM)2-7 recruitment to origins in G1 requires origin recognition complex (ORC), Cdt1, and Cdc6, and activation at G1/S requires MCM10 and the protein kinases Cdc7 and S-Cdk, which together recruit Cdc45, a putative MCM2-7 cofactor required for origin unwinding. Here, we show that the Xenopus BRCA1 COOH terminus repeat-containing Xmus101 protein is required for loading of Cdc45 onto the origin. Xmus101 chromatin association is dependent on ORC, and independent of S-Cdk and MCM2-7. These results define a new factor that is required for Cdc45 loading. Additionally, these findings indicate that the initiation complex assembly pathway bifurcates early, after ORC association with the origin, and that two parallel pathways, one controlled by MCM2-7, and the other by Xmus101, cooperate to load Cdc45 onto the origin.