Morphological and morphometric measurement of the temporomandibular joint of small and medium-weight dogs with different skull shapes

BackgroundThe recognition and diagnosis of canine temporomandibular joint (TMJ) disease can be a challenge, often leaving them undiagnosed. Although computed tomography (CT) has proved to be highly efficacious in detecting joint disease in the TMJ, morphometric and morphological studies of the normal TMJ have been scarce. Especially, skull type specific anatomical differences of the TMJ in dogs of different weights and skull morphologies have received limited attention.ObjectiveThis study aimed to compare the TMJ morphologies of dogs across different weight classes and skull types.Study designRetrospective study.MethodsCT scans were used to measure the depth and width of the Fossa mandibularis and two angles between the Fossa mandibularis and the Caput mandibulae in a total of 92 dogs and 182 mandibular joints, respectively.ResultsThe TMJ varied in terms of weight groups and skull indices. Shallow mandibular pits, underdeveloped retroarticular processes, and reduced joint congruency were observed particularly in light-weight and brachycephalic dogs. Conversely, dolichocephalic animals displayed deep joint pits, pronounced joint congruency, and a well-developed Processus retroarticularis.Main limitationsObserver learning curve; not every skull shape was represented in each weight group

Development and Validation of an Examination Protocol for Arthroscopic Evaluation of the Temporomandibular Joint in Dogs

Due to the previously limited intra-articular diagnostic possibilities of the canine temporomandibular joint, an examination protocol for the canine temporomandibular joint (TMJ) was developed and tested in this study using a needle arthroscope. In total, the discotemporal (DTJ) and discomandibular (DMJ) joint compartments of 32 animals (64 TMJs) were examined arthroscopically. During the examinations, 15 anatomical landmarks per joint side were evaluated in regard to their visibility and accessibility. All arthroscopies were performed by the same examiner and the same assistant to ensure standard methods were applied. The examination procedure which was developed here proved to be a reliable tool for examining this joint. The 15 anatomical landmarks that were to be examined could be reliably visualised and assessed in all TMJs with a certainty of 86% to 100% by both observers. This tool provides clinicians with a reliable examination aid for everyday practice and ensures the comparability of results. In the future, this could provide an opportunity to better diagnose and treat TMJ pathologies

Atg21 organizes Atg8 lipidation at the contact of the vacuole with the phagophore

Coupling of Atg8 to phosphatidylethanolamine is crucial for the expansion of the crescent-shaped phagophore during cargo engulfment. Atg21, a PtdIns3P-binding beta-propeller protein, scaffolds Atg8 and its E3-like complex Atg12–Atg5-Atg16 during lipidation. The crystal structure of Atg21, in complex with the Atg16 coiled-coil domain, showed its binding at the bottom side of the Atg21 betapropeller. Our structure allowed detailed analyses of the complex formation of Atg21 with Atg16 and uncovered the orientation of the Atg16 coiled-coil domain with respect to the membrane. We further found that Atg21 was restricted to the phagophore edge, near the vacuole, known as the vacuole isolation membrane contact site (VICS). We identified a specialized vacuolar subdomain at the VICS, typical of organellar contact sites, where the membrane protein Vph1 was excluded, while Vac8 was concentrated. Furthermore, Vac8 was required for VICS formation. Our results support a specialized organellar contact involved in controlling phagophore elongation