Zygomatic bone shape in intentional cranial deformations: a model for the study of the interactions between skull growth and facial morphology

Intentional cranial deformations (ICD) were obtained by exerting external mechanical constraints on the skull vault during the first years of life to permanently modify head shape. The repercussions of ICD on the face are not well described in the midfacial region. Here we assessed the shape of the zygomatic bone in different types of ICDs. We considered 14 non-deformed skulls, 19 skulls with antero-posterior deformation, nine skulls with circumferential deformation and seven skulls with Toulouse deformation. The shape of the zygomatic bone was assessed using a statistical shape model after mesh registration. Euclidian distances between mean models and Mahalanobis distances after canonical variate analysis were computed. Classification accuracy was computed using a cross-validation approach. Different ICDs cause specific zygomatic shape modifications corresponding to different degrees of retrusion but the shape of the zygomatic bone alone is not a sufficient parameter for classifying populations into ICD groups defined by deformation types. We illustrate the fact that external mechanical constraints on the skull vault influence midfacial growth. ICDs are a model for the study of the influence of epigenetic factors on craniofacial growth and can help to understand the facial effects of congenital skull malformations such as single or multi-suture synostoses, or of external orthopedic devices such as helmets used to correct deformational plagiocephaly.R.H.K. and S.K. were supported by the Union des Blessés de la Face et de la Tête, Fondation des ‘Gueules Cassées’. S.K. was supported by the Fédération Française d’Orthodontie (FFO)

Maxillary shape after primary cleft closure and before alveolar bone graft in two different management protocols: A comparative morphometric study

AIM AND SCOPE: Result assessment in cleft surgery is a technical challenge and requires the development of dedicated morphometric tools. Two cohorts of patients managed according to two different protocols were assessed at similar ages and their palatal shape was compared using geometric morphometrics. MATERIAL AND METHODS: Ten patients (protocol No. 1) benefited from early lip closure (1-3 months) and secondary combined soft and hard palate closure (6-9 months); 11 patients (protocol No. 2) benefited from later combined lip and soft palate closure (6 months) followed by hard palate closure (18 months). Cone-Beam Computed Tomography (CBCT) images were acquired at 5 years of age and palatal shapes were compared between protocols No. 1 and No. 2 using geometric morphometrics. RESULTS: Protocols No. 1 and No. 2 had a significantly different timing in their surgical steps but were assessed at a similar age (5 years). The inter-canine distance was significantly narrower in protocol No. 1. Geometric morphometrics showed that the premaxillary region was located more inferiorly in protocol No. 1. CONCLUSION: Functional approaches to cleft surgery (protocol No. 2) allow obtaining larger inter-canine distances and more anatomical premaxillary positions at 5 years of age when compared to protocols involving early lip closure (protocol No. 1). This is the first study comparing the intermediate results of two cleft management protocols using 3D CBCT data and geometric morphometrics. Similar assessments at the end of puberty are required in order to compare the long-term benefits of functional protocols

Late subadult ontogeny and adult aging of the human thorax reveals divergent growth trajectories between sexes

Sexual dimorphism is an important feature of adult thorax morphology, but when and how sex-related differences in the ribcage arise during ontogeny is poorly known. Previous research proposed that sex-related size differences in the nasal region arise during puberty. Therefore, we explore whether ribcage sexual dimorphism also arises at that time and whether this sexual dimorphism is maintained until old age. We measured 526 (semi)landmarks on 80 CT-based human ribcage reconstructions, on individuals ranging from 7 to 65 year-old. The 3D coordinates were submitted to the Procrustes superimposition and analyzed. Our results show that the trajectories of thorax size and shape between sexes diverge at around 12 years of age, and continue slightly diverging until old age. The differential ontogenetic trends cause adult male ribcages to become deeper, shorter, and wider than female. Our results are consistent with the evidence from the cranial respiratory system, with the development of sexual dimorphism probably related to changes in body composition during puberty combined with changes in the reproductive system

Description mathématique de la démyélinisation concentrique

La sclérose concentrique de Balô est une variante de la sclérose en plaques (SEP) caractérisée la présence de foyers de démyélinisation en anneaux. L'origine de l'alternance de zones de substance blanche saine et de zones détruites est mystérieuse. Les événements cellulaires qui provoquent la maladie de Balô sont probablement les mêmes que ceux impliqués dans la SEP. L'apparition d'anneaux serait alors la conséquence d'une configuration particulière de paramètres communs à toutes les formes de SEP. L'analogie entre la sclérose de Balô et le phénomène de précipitation périodique de Liesegang a été relevée dès le début du vingtième siècle et se fonde sur la théorie de la supersaturation d'Ostwald. Il est toutefois difficile de trouver un équivalent biologique simple de la supersaturation. Par ailleurs, les recherches récentes sur les anneaux de Liesegang amènent à une réfutation de la théorie d'Ostwald. Les théories de postnucléation mettent en jeu le passage par une étape intermédiaire colloïdale lors de la réaction de précipitation. La présente étude s'inspire de ces idées en proposant un modèle cellulaire chémotactique pour la sclérose de Balô. Historiquement, la conception du phénomène de Liesegang est passée d'une échelle moléculaire à une échelle colloïdale. Le retour sur l'analogie entre ce phénomène et la sclérose de Balô amène parallèlement à proposer un scénario cellulaire plutôt qu'un modèle strictement fondé sur la diffusion moléculaire. Le modèle chémotactique de la sclérose concentrique est d'une remarquable robustesse et s'affranchit d'hypothèses biologiques fortes comme le potentiel de protection de la théorie du préconditionnement. La morphogenèse est le résultat de l'auto-organisation de populations cellulaires soumises à des processus d'attraction non-linéaires. Une forte agressivité microgliale ou une charge importante en cellules démyélinisantes favorise l'apparition de figures concentriques. Ce modèle corrobore l'existence de liens mécanistiques entre la SEP et la sclérose concentrique et confirme que des événements cellulaires élémentaires peuvent être à l'origine de motifs pathologiques élaborés.NANTES-BU Médecine pharmacie (441092101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Agnathan brain anatomy and craniate phylogeny

Abstract Khonsari, R.H., Li, B., Vernier, P., Northcutt, R.G. and Janvier, P. 2009. The anatomy of the agnathan brain and craniate phylogeny. -Acta Zoologica (Stockholm), 90 (Suppl. 1): 52-68 The central nervous system of hagfishes displays unique characteristics that are distinct from any other craniate neuroanatomic features. Whether these hagfish characters are general for all craniates, autapomorphies of hagfishes, or merely a derived state of the general cyclostome condition is still a matter of debate that relates to the question of the monophyly or paraphyly of the cyclostomes. The present cladistic study includes 123 neuroanatomical characters of nine chordate species and supports cyclostome paraphyly, in contrast to most current molecular sequence-based phylogenies, which support cyclostome monophyly. An understanding of the unique neural characters in hagfishes is critical to inspiring further comparative and developmental studies with regards to these two conflicting results and the very deep divergence between craniates and their presumed sister groups. The recent access to hagfish developmental data may provide exciting perspectives in the understanding and characterization of the basalmost craniate node and the interpretation of hagfish brain structure

Évaluer la plasticité crânienne chez l’Homme : impact des déformations artificielles sur les structures masticatrices et basicrâniennes

International audienceArtificial cranial deformations (ACD) are a widespread cultural practice found in numerous historical and prehistoric contexts. Their study can yield valuable insight into craniofacial growth, specifically into the interactions between neurocranial and basicranial modules. This study seeks to reinvestigate the presumed effect of ACD on basicranial and masticatory elements by applying a 3D geometric morphometric approach to CT scans. A total of 51 French and Bolivian skulls, representing anteroposterior and circumferential deformations and including undeformed individuals, were scanned, and 3D landmarks were submitted to between-group principal components analysis and two-block partial least-squares analysis. Our results illustrate changes in basicranial shape and in cranial base angles induced by ACD, as well as in masticatory geometry, namely in the relative position of the mandibular fossae. Furthermore, our findings highlight differential effects of the various deformation types, which suggest that patterns of covariation between modified vaults and their associated basicrania are more complex than previously assumed, thereby stressing the degree of plasticity in human craniofacial growth.Les déformations artificielles du crâne (DAC) désignent une pratique culturelle observée dans de nombreux contextes historiques et préhistoriques. Leur étude nous renseigne sur la croissance craniofaciale, notamment l’interaction entre les modules neuro- et basicrâniens. L’objectif de cette étude est de réexaminer l’effet présumé des DAC sur les éléments basicrâniens et masticateurs, en appliquant des méthodes de morphométrie géométrique 3D à des analyses tomodensitométriques. Au total, 51 crânes d’origine française et bolivienne, représentant les déformations antéropostérieures et circonférentielles, ainsi que des individus non déformés, ont été scannés, et les coordonnées de points de repère 3D ont été étudiées par analyse en composantes principales intergroupes ainsi que par régression des moindres carrés partiels (PLS) avec deux blocs de covariation. Nos résultats illustrent des changements de conformation et d’angulation de la base du crâne, induits par les DAC, ainsi que de la géométrie masticatrice, notamment concernant les positions relatives de la fosse mandibulaire et du reste de la base du crâne. Nos observations soulignent des effets différentiels selon les types de déformation, ce qui suggère que les patrons de covariation entre une voûte modifiée et la base crânienne sont plus complexes que précédemment proposé

Agnathan brain anatomy and craniate phylogeny

11th International Symposium on Early and Lower Vertebrates Uppsala, SWEDEN, AUG 13, 2007International audienceThe central nervous system of hagfishes displays unique characteristics that are distinct from any other craniate neuroanatomic features. Whether these hagfish characters are general for all craniates, autapomorphies of hagfishes, or merely a derived state of the general cyclostome condition is still a matter of debate that relates to the question of the monophyly or paraphyly of the cyclostomes. The present cladistic study includes 123 neuroanatomical characters of nine chordate species and supports cyclostome paraphyly, in contrast to most current molecular sequence-based phylogenies, which support cyclostome monophyly. An understanding of the unique neural characters in hagfishes is critical to inspiring further comparative and developmental studies with regards to these two conflicting results and the very deep divergence between craniates and their presumed sister groups. The recent access to hagfish developmental data may provide exciting perspectives in the understanding and characterization of the basalmost craniate node and the interpretation of hagfish brain structure

Paul Tessier facial reconstruction in 1970 Iran, a series of post-noma defects

International audienceBackground : Paul Tessier was a pioneering plastic surgeon who founded craniofacial surgery and had an international influence in the field of reconstructive surgery. We reviewed his techniques in the reconstruction of post-noma defects in Iran in the late 1970s.Patients and Methods : We studied a series of 23 patients operated on by Tessier from 1974 to 1978 in Iran (property of Association Française des Chirurgiens de la Face). They all suffered from noma in childhood with major facial defects.Results : Ten suffered from simple lip and cheek defects, nine also from nose defects and four from extensive facial defects. Abbe flaps were used in 15 patients to reconstruct the lips completed by commissuroplasty in six patients. Nose defects were reconstructed with nasofrontal flaps (ten cases). The outer cheek was reconstructed with a rotation flap (four cases), or with a frontotemporal flap (six cases). The inner cheek was reconstructed using a Barron−Tessier myocutaneous flap (ten cases). Of the 23 patients, flap necrosis occurred in five cases.Conclusions : Tessier was a pioneering plastic surgeon who used local flaps to reconstruct these important facial defects. He had a high rate of success, although nowadays local flaps are commonly replaced by free flaps

The anatomy of the agnathan brain and craniate phylogeny.

International audienceThe central nervous system of hagfishes displays unique characteristics that are distinct from any other craniate neuroanatomic features. Whether these hagfish characters are general for all craniates, autapomorphies of hagfishes, or merely a derived state of the general cyclostome condition is still a matter of debate that relates to the question of the monophyly or paraphyly of the cyclostomes. The present cladistic study includes 123 neuroanatomical characters of nine chordate species and supports cyclostome paraphyly, in contrast to most current molecular sequence-based phylogenies, which support cyclostome monophyly. An understanding of the unique neural characters in hagfishes is critical to inspiring further comparative and developmental studies with regards to these two conflicting results and the very deep divergence between craniates and their presumed sister groups. The recent access to hagfish developmental data may provide exciting perspectives in the understanding and characterization of the basalmost craniate node and the interpretation of hagfish brain structure