The mandibular (glenoid) fossa is of particular importance with regard to the biomechanics of the temporomandibular joint. In particular, the anterior aspect of the mandibular fossa, formed by the articular eminence, influences mandibular depression and protrusion. Accordingly, the mandibular fossa and articular eminence are common structures to undergo surgical alteration (e.g. eminectomy). Therefore, this study analyzed the contour of the mandibular fossa in the sagittal plane to improve the understanding of how the native shape of the mandibular fossa may be implicated in the biomechanics of the temporomandibular joint. The study assessed a total of 39 mandibular fossae via three‐dimensional models of human crania. The three‐dimensional crania models were manipulated such that the model could be split in the sagittal plane in the center of the mandibular fossa. Two‐dimensional renderings of the sagittal planes bifurcating the mandibular fossae were then utilized to perform geometric morphometric analysis utilizing 15 sliding landmarks spanning from the post‐glenoid tubercle to the apex of the articular eminence. Procrustes superimposition revealed a mean contour that when interpolated is given by the equation y ≈ 12.973x6 − 7.2434x5 − 10.861x4 + 4.2187x3 + 3.2365x2 − 0.3056x − 0.1303. Principle component analysis demonstrates 84.90% of the shape variance within two principle components (PC1=70.56% of variance; PC2=14.34% of variance). Also, the left‐ and right‐sided contours did not differ significantly (Mahalanobis distance=2.305; T2=54.2889; p=0.8042). The information presented here provides insight with regard to the average contour of the mandibular fossa as well as most likely contour variation. Therefore, this information may be applied in the context of joint biomechanics to better understand the function and limitations of the temporomandibular joint.Support or Funding InformationWV Research Challenge Fund [HEPC.dsr.17.06] and [HEPC.dsr.14.13]This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Based on the observation that some crania exhibit a pronounced marginal tubercle, whereas others do not, this study assessed the contour of the zygomatic bone hypothesizing that female and male crania would exhibit different contours. The study included 616 norma lateralis images of a mixed sample of female (n=252) and male (n=318) cranial sides. Images from crania of questionable sex and were excluded from analysis between sexes. The linear distance from the zygomaticofrontal suture to the jugale was calculated in addition to the length of the posterior border of the frontal process of the zygomatic bone to determine the degree of deviation from a straight line. The contour length between males and females did not differ (t=1.577(593); p=0.12) nor did the degree of deviation from a straight line (t=1.808(593); p=0.07). Independent of sex, however, there were significant differences in the aforementioned parameters with regard to side (t=5.589(614); p<0.0001 and t=3.742(614); p=0.0002, respectively). Procrustes superimposition demonstrated the average contour which can be given as y≈44.074x4 + 0.7995x3 −2.6286x2 −0.0122x + 0.0182. Principle component analysis explained 74.6% of shape variation with the first two principle components (PC1=48.8%; PC2=25.8%). With regard to differences in the shape of the contour between sides or sexes, discriminant function analysis revealed no significant shape difference (T2=338.7; p=0.15 and T2=244.3; p=0.94, respectively). However, canonical variate analysis demonstrated statistically significant shape differences among sexes with regard to side. Female right and left sides demonstrated the most shape difference (Mahalanobis distance=2.33) whereas the least shape difference was found among right sides between males and females (Mahalanobis distance=1.83). The results of this study reveal morphological variation in the posterior margin of the frontal process of the zygomatic bone that distinguishes crania based upon sex and laterality.Support or Funding InformationWV Research Challenge Fund [HEPC.dsr.17.06] and [HEPC.dsr.14.13]This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The temporomandibular joint (TMJ) is a complex and constantly moving part of the human body with over 2000 movements a day. Because of the joint's complex movements, symptomatic temporomandibular dysfunction (TMD) occurs in 5–12% of the population. Prosthetics may be used to treat TMD; yet, with potential anatomic variation, prosthetics may suffer from not being specific enough to a patient. Identifying and categorizing anatomical variations may result in improved treatment. This study analyzed the anterior crest of the mandibular fossa by landmarking 40 equidistant points from the most medial to lateral aspects of the crest, on both the left and right sides of the crania. The points were used to compare both side and sexual dimorphism of the fossa's anterior margin. Principle component analysis showed that 84.0 % of morphological variance is accounted for by the first two principle components (PC1= 66.4% PC2= 17.6%). Canonical variate analysis showed a significant difference between the sexes and sides (Side: Mahalanobis distance= 2.5399, p<0.0001) (Sex: Mahalanobis distance= 1.7350, p<0.0001). The information assessed from this study provides insight with regard to side and sexual dimorphism of the anterior crest of the mandibular fossa. The results of this study may aid in creating a TMJ prosthetic with a higher success rate than the stock models available today.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Francisella tularensis is classified by the CDC as a Category A bioterrorism agent because of its ease of aerosolization, low infection dose, and high mortality rate. Inhalation of as few as one bacterium is sufficient to cause an acute pneumonia that is lethal in up to 60% of individuals if left untreated. Therefore, the intentional release of antibiotic-resistant strains of F. tularensis would be disastrous and new therapeutics targeting this bacterium must be developed to make our nation safer against a potential terror attack. We have identified a family of resazurin-based compounds called resazomycins that exhibit robust antimicrobial activity against select Gram-negative bacteria, including F. tularensis. The mechanism of action of these antibiotics is not known. To identify potential targets of resazomycins, we performed a high throughput screen to identify resistant isolates and then performed whole genome sequencing on each isolate. Multiple F. tularensis isolates had a mutation in the gene FTL_0073 which encodes for Francisella lipoprotein A (FlpA). Based on the localization of FlpA to the outer membrane, we hypothesize that this protein could be a target of resazomycins or may play a role in uptake of this antibiotic. To address these two hypotheses, we are currently working to generate a flpA disruption and null deletion mutant using standard molecular genetic techniques. Once the mutants are generated, we will first confirm the sensitivity of the flpA mutants to resazomycins. Then, we will test the mutant for defects in uptake of resazomycins. Understanding the role of flpA in resazomycin susceptibility would facilitate further development of these compounds as potential treatments for tularemia.
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