Mapping molar shapes on signaling pathways.

A major challenge in evolutionary developmental biology is to understand how genetic mutations underlie phenotypic changes. In principle, selective pressures on the phenotype screen the gene pool of the population. Teeth are an excellent model for understanding evolutionary changes in the genotype-phenotype relationship since they exist throughout vertebrates. Genetically modified mice (mutants) with abnormalities in teeth have been used to explore tooth development. The relationship between signaling pathways and molar shape, however, remains elusive due to the high intrinsic complexity of tooth crowns. This hampers our understanding of the extent to which developmental factors explored in mutants explain developmental and phenotypic variation in natural species that represent the consequence of natural selection. Here we combine a novel morphometric method with two kinds of data mining techniques to extract data sets from the three-dimensional surface models of lower first molars: i) machine learning to maximize classification accuracy of 22 mutants, and ii) phylogenetic signal for 31 Murinae species. Major shape variation among mutants is explained by the number of cusps and cusp distribution on a tooth crown. The distribution of mutant mice in morphospace suggests a nonlinear relationship between the signaling pathways and molar shape variation. Comparative analysis of mutants and wild murines reveals that mutant variation overlaps naturally occurring diversity, including more ancestral and derived morphologies. However, taxa with transverse lophs are not fully covered by mutant variation, suggesting experimentally unexplored developmental factors in the evolutionary radiation of Murines.

Metameric variation of upper molars in hominoids and its implications for the diversification of molar morphogenesis.

Metameric variation of molar size is in part associated with the dietary adaptations of mammals and results from slight alterations of developmental processes. Humans and great apes exhibit conspicuous variation in tooth morphology both between taxa and across tooth types. However, the manner in which metameric variation in molars emerged among apes and humans via evolutionary alterations in developmental processes remains largely unknown. In this study, we compare the enamel-dentine junction of the upper molars of humans-which closely correlates with morphology of the outer enamel surface and is less affected by wear-with that of the other extant hominoids: chimpanzees, bonobos, gorillas, orangutans, and gibbons. We used the morphometric mapping method to quantify and visualize three-dimensional morphological variation, and applied multivariate statistical analyses. Results revealed the following: 1) extant hominoids other than humans share a common pattern of metameric variation characterized by a largely linear change in morphospace; this indicates a relatively simple graded change in metameric molar shape; 2) intertaxon morphological differences become less distinct from the mesial to distal molars; and 3) humans diverge from the extant ape pattern in exhibiting a distinct metameric shape change trajectory in the morphospace. The graded shape change and lower intertaxon resolution from the mesial to distal molars are consistent with the concept of a 'key' tooth. The common metameric pattern observed among the extant nonhuman hominoids indicates that developmental patterns underlying metameric variation were largely conserved during ape evolution. Furthermore, the human-specific metameric pattern suggests considerable developmental modifications in the human lineage.

Post-operative pain control following arthroscopic rotator cuff repair: peri-articular injection versus interscalene brachial plexus block.

PURPOSE: To compare post-operative pain relief with peri-articular injection (PI) versus interscalene brachial plexus block (IBPB) after arthroscopic rotator cuff repair (ARCR) surgery. METHODS: We retrospectively reviewed 121 consecutive patients undergoing ARCR surgery divided into two groups: the PI group and the IBPB group. We compared complications and self-reported pain score measured using a Numerical Rating Scale (NRS) during the initial 24 hours after surgery. RESULTS: The NRS scores recorded in the recovery room (0), 0.5, and four hours post-operatively were higher in the PI group (n = 38) than the IBPB group (n = 52) (2.1 vs. 0.8, p = 0.014; 1.4 vs. 0.5, p = 0.0069; and 1.3 vs. 0.5, p = 0.012, respectively). However, the NRS scores recorded at 16, 20, and 24 hours post-operatively were lower in the PI group than in the IBPB group (1.4 vs. 3.1, p < 0.0001; 1.4 vs. 3.2, p < 0.0001; and 1.7 vs. 3.2, p = 0.00046, respectively). The incidences of post-operative nausea and temporary numbness in the upper arm were significantly lower in the PI group than in the IBPB group (7.9% vs. 33%, p = 0.0052; and 13% vs. 85%, p < 0.0001, respectively). CONCLUSIONS: Although IBPB provided superior pain control during the initial few hours after ARCR surgery, PI was superior from 16 to 24 hours post-operatively. The rates of side effects, such as nausea and temporary arm numbness, were also lower in the PI group than in the IBPB group.

Maternal undernutrition during early pregnancy inhibits postnatal growth of the tibia in the female offspring of rats by alteration of chondrogenesis.

Epidemiological research has suggested that birth weights are correlated with adult leg lengths. However, the relationship between prenatal undernutrition (UN) and postnatal leg growth remains controversial. We investigated the effects of UN during early pregnancy on postnatal hindlimb growth and determined whether early embryonic malnutrition affects the functions of postnatal chondrocytes in rats. Undernourished Wistar dams were fed 40% of the daily intake of rats in the control groups from gestational days 5.5-11.5, and femurs, tibias, and trunks or spinal columns were morphologically measured at birth and at 16 weeks of age in control and undernourished offspring of both sexes. We evaluated cell proliferation and differentiation of cultured chondrocytes derived from neonatal tibias of female offspring and determined chondrocyte-related gene expression levels in neonatal epiphysis and embryonic limb buds. Tibial lengths of undernourished female, but not male, offspring were longer at birth and shorter at 16 weeks of age (p < .05) compared with those of control rats. In chondrocyte culture studies, stimulating effects of IGF-1 on cell proliferation (p < .01) were significantly decreased and levels of type II collagen were lower in female undernourished offspring (p < .05). These phenomena were accompanied by decreased expression levels of Col2a1 and Igf1r and increased expression levels of Fgfr3 (p < .05), which might be attributable to the decreased expression of specificity protein 1 (p < .05), a key transactivator of Col2a1 and Igf1r. In conclusion, UN stress during early pregnancy reduces postnatal tibial growth in female offspring by altering the function of chondrocytes, likely reflecting altered expression of gene transactivators.

Intra- and inter-observer reproducibility of shoulder laxity tests: Comparison of the drawer, modified drawer and load and shift tests.

BACKGROUND: Conventional tests of shoulder laxity have been shown to have poor reliability due to the difficulty in palpating the subtle movements of the shoulder joint beneath the musculature. Modified drawer test that is performed while the soft tissues surrounding the shoulder are loosened has been proposed to facilitate glenohumeral joint movement and improve reliability. We hypothesised that the modified drawer test would have an improved intra- and inter-observer reproducibility in comparison to the drawer and load and shift tests. Correlation of shoulder laxity measured by these tests with generalized joint laxity was also assessed. METHODS: Forty healthy volunteers underwent bilateral shoulder examination in the clinic using the three tests for anterior and posterior laxity assessment by a consultant shoulder surgeon and a resident. The examination was repeated three months later by the same examiners in the same cohort. Intra- and inter- observer reproducibility was calculated using Kappa values. The correlation of shoulder with generalized joint laxity was also investigated. RESULTS: The modified drawer test showed significantly improved intra-observer reproducibility compared to the drawer test, but not to the load and shift (κ = 0.173, -0.042, and 0.009, respectively). There were no significant differences in the inter-observer reproducibility between the three tests (κ = 0.054, 0.055, and 0.056, respectively). Moderate correlation was noted between shoulder and generalized joint laxity when modified drawer test was used (r = 0.417). CONCLUSIONS: The modified drawer test improves intra- but not inter- observer reproducibility compared to the drawer test. Shoulder laxity assessed by the modified test correlated to generalized joint laxity. The modified drawer test has an improved reproducibility and correlation to generalized joint laxity over the conventional tests.

MRI for the diagnosis of scapular dyskinesis: a report of two cases.

Scapular dyskinesis describes the altered position of the scapula and/or abnormal movements of the scapulothoracic joint. It is caused by bony anatomical variations, bursitis, tumors, and muscular pathological conditions including loss of innervation and fibrosis. Scapular dyskinesis is just as often subclinical as it is symptomatic, and as the periscapular anatomical changes may not result in patient symptoms, a precise diagnosis of the etiology and pathophysiology has been a challenge. Scapular bony prominence is a common etiology of scapular dyskinesis, but does not always result in morbidity. We report a case of a 39-year-old man in whom an extensive MRI with fluid-sensitive imaging sequences covering the whole of the scapula was beneficial in diagnosing the inflammation adjacent to the bony deformity, which confirmed the etiology of scapular dyskinesis. Furthermore, in a 41-year old man without any anatomical variances, a similar MRI showed inflammation at the subscapular fossa that suggested altered scapular kinematics. An arthroscopic debridement of the lesion improved the symptoms. MRI in conjunction with plain radiographs, CT and physical examination enabled a precise diagnosis of the etiology. Fluid-sensitive MR images are important in defining the presence of inflammation, and are beneficial in determining the pathological significance of findings through other diagnostic measures.

Exploring metameric variation in human molars: a morphological study using morphometric mapping.

Human molars exhibit a type of metameric variation, which is the difference in serially repeated morphology within an organism. Various theories have been proposed to explain how this variation is brought about in the molars. Actualistic data that support the theories, however, are still relatively scarce because of methodological limitations. Here we propose new methods to analyse detailed tooth crown morphologies. We applied morphometric mapping to the enamel-dentine junction of human maxillary molars and examined whether odontogenetic models were adaptable to human maxillary molars. Our results showed that the upper first molar is phenotypically distinct among the maxillary molars. The average shape of the upper first molar is characterized by four well-defined cusps and precipitous surface relief of the occlusal table. On the other hand, upper third molar is characterized by smooth surface relief of the occlusal table and shows greater shape variation and distinct distribution patterns in morphospace. The upper second molar represents an intermediate state between first and third molar. Size-related shape variation was investigated by the allometric vector analysis, and it appeared that human maxillary molars tend to converge toward the shape of the upper first molar as the size increases. Differences between the upper first molar and the upper second and third molar can thus be largely explained as an effect of allometry. Collectively, these results indicate that the observed pattern of metameric variation in human molars is consistent with odontogenetic models of molar row structure (inhibitory cascade model) and molar crown morphology (patterning cascade model). This study shows that morphometric mapping is a useful tool to visualize and quantify the morphological features of teeth, which can provide the basis for a better understanding of tooth evolution linking morphology and development.

Combined Arthroscopic Bankart Repair and Coracoid Process Transfer to Anterior Glenoid for Shoulder Dislocation in Rugby Players: Evaluation Based on Ability to Perform Sport-Specific Movements Effectively.

PURPOSE: To evaluate the outcomes of a combination of an arthroscopic Bankart repair and an open Bristow procedure in relation to the subjective quality of performance in movements that are typical in rugby. METHODS: Forty shoulders in 38 players who underwent surgery for traumatic anterior instability of the shoulder were reviewed. In all cases, arthroscopic Bankart repair was followed by a Bristow procedure, with preservation of the repaired capsular ligaments, during the same operation. The mean age at the time of surgery was 21 years. Patients were asked to describe common rugby maneuvers (tackle, hand-off, jackal, and saving) preoperatively and postoperatively as "no problem," "insufficient," or "impossible." RESULTS: There were no recurrent dislocations at a mean follow-up of 30.5 months. The mean Rowe score improved significantly from 65.0 (range, 55 to 75) to 97.5 (range, 95 to 100) (P < .001) after surgery. Preoperatively, regarding the tackling motion, none of the patients reported having no problem, whereas the ability was described as insufficient for 23 shoulders and impossible for 17 shoulders. Postoperatively, no problem with tackling was reported for 36 shoulders, whereas insufficiency was reported for 4. The results for the hand-off, jackal, and saving maneuvers were similar (P < .001). No patient rated any of the motions as impossible postoperatively. CONCLUSIONS: This combined surgical procedure clearly is effective in preventing recurrent dislocation in rugby players; however, some players complained of insufficiency in the quality of their play when they were tackling or performing other rugby-specific movements. LEVEL OF EVIDENCE: Level IV, case series.

Quantitative and qualitative analyses of subacromial impingement by kinematic open MRI.

PURPOSE: Quantitative and qualitative kinematic analyses of subacromial impingement by 1.2T open MRI were performed to determine the location of impingement and the involvement of the acromioclavicular joint. METHODS: In 20 healthy shoulders, 10 sequential images in the scapular plane were taken in a 10-s pause at equal intervals from 30° to maximum abduction in neutral and internal rotation. The distances between the rotator cuff (RC) and the acromion and the acromioclavicular joint were measured. To comprehend the positional relationships, cadaveric specimens were also observed. RESULTS: Although asymptomatic, the RC came into contact with the acromion and the acromioclavicular joint in six and five cases, respectively. The superior RC acted as a depressor for the humeral head against the acromion as the shoulder elevated. The mean elevation angle and distance at the closest position between the RC and the acromion in neutral rotation were 93.5° and 1.6 mm, respectively, while those between the RC and the acromioclavicular joint were 86.7° and 2.0 mm. When comparing this distance and angle, there was no significant difference between the RC to the acromion and to the acromioclavicular joint. The minimum distance between the RC and the acromion was significantly shorter than that between the greater tuberosity and the acromion. The location of RC closest to the acromion and the acromioclavicular joint differed significantly. CONCLUSION: Although asymptomatic, contact was found between the RC and the acromion and the acromioclavicular joint. The important role of the RC to prevent impingement was observed, and hence, dysfunction of the RC could lead to impingement that could result in a RC lesion. The RC lesions may differ when they are caused by impingement from either the acromion or the acromioclavicular joint.

Patterns of morphological variation in enamel-dentin junction and outer enamel surface of human molars.

Tooth crown patterning is governed by the growth and folding of the inner enamel epithelium (IEE) and the following enamel deposition forms outer enamel surface (OES). We hypothesized that overall dental crown shape and covariation structure are determined by processes that configurate shape at the enamel-dentine junction (EDJ), the developmental vestige of IEE. This this hypothesis was tested by comparing patterns of morphological variation between EDJ and OES in human permanent maxillary first molar (UM1) and deciduous second molar (um2). Using geometric morphometric methods, we described morphological variation and covariation between EDJ and OES, and evaluated the strength of two components of phenotypic variability, canalization and morphological integration, in addition to the relevant evolutionary flexibility, i.e. the ability to respond to selective pressure. The strength of covariation between EDJ and OES was greater in um2 than in UM1, and the way that multiple traits covary between EDJ and OES was different between these teeth. The variability analyses showed that EDJ had less shape variation and a higher level of morphological integration than OES, which indicated that canalization and morphological integration acted as developmental constraints. These tendencies were greater in UM1 than in um2. On the other hand, EDJ and OES had a comparable level of evolvability in these teeth. Amelogenesis could play a significant role in tooth shape and covariation structure, and its influence was not constant among teeth, which may be responsible for the differences in the rate and/or period of enamel formation.