Nanoporous hydroxyapatite/sodium titanate bilayer on titanium implants for improved osteointegration.

Objective: The aim of this study was to improve the strength and quality of the titanium-hydroxyapatite interface in order to prevent long-term failure of the implanted devices originating from coating delamination and to test it in an in-vivo model.

Methods: Ti disks and dental commercial implants were etched in Kroll solution. Thermochemical treatments of the acid-etched titanium were combined with sol-gel hydroxyapatite (HA) coating processes to obtain a nanoporous hydroxyapatite/sodium titanate bilayer.

Cell Alignment Driven by Mechanically Induced Collagen Fiber Alignment in Collagen/Alginate Coatings.

For many years it has been a major challenge to regenerate damaged tissues using synthetic or natural materials. To favor the healing processes after tendon, cornea, muscle, or brain injuries, aligned collagen-based architectures are of utmost interest. In this study, we define a novel aligned coating based on a collagen/alginate (COL/ALG) multilayer film.

Left-sided predominance of hypodontia irrespective of cleft sidedness in a French population.

Objective: Individuals with oral clefts exhibit considerably more dental anomalies than do individuals without clefts. Our aim was to evaluate the prevalence of tooth agenesis in a sample composed of 124 children (81 boys and 43 girls, mean age 12.5 years) with clefts registered with the Cleft Palate Center in Strasbourg (France).

Bone formation induced by growth factors embedded into the nanostructured particles.

Tissue engineering has merged with stem cell biotechnology with development of new sources of transplantable biomaterials for the treatment of bone tissue diseases. Bone defects are expected to benefit from this new biotechnology because of the low self-regenerating capacity of bone matrix secreting cells. The differentiation of stem cells to bone cells using bi-functionalized multilayered particles is presented.

Subtle Morphological Changes in the Mandible of Tabby Mice Revealed by Micro-CT Imaging and Elliptical Fourier Quantification.

X-linked hypohidrotic ectodermal dysplasia (XLHED) is a genetic disorder due to a mutation of the EDA gene and is mainly characterized by an impaired formation of hair, teeth and sweat glands, and craniofacial dysmorphologies. Although tooth abnormalities in Tabby (Ta) mutant mice - the murine model of XLHED - have been extensively studied, characterization of the craniofacial complex, and more specifically the mandibular morphology has received less attention. From 3D micro-CT reconstructions of the left mandible, the mandibular outline observed in lateral view, was quantified using 2D elliptical Fourier analysis.

Targeted apc;twist double-mutant mice: a new model of spontaneous osteosarcoma that mimics the human disease.

TWIST and adenomatosis polyposis coli (APC) are critical signaling factors in normal bone development. In previous studies examining a homogeneously treated cohort of pediatric osteosarcoma patients, we reported the frequent and concurrent loss of both TWIST and APC genes. On these bases, we created a related animal model to further explore the oncogenic cooperation between these two genes.

[Genetic origin of non-syndromic cleft lip and palate. TWIST, a candidate gene? Research protocol].

Non syndromic cleft lip and palate (CLP) is the most frequent human malformation. CLP is of complex inheritance and at least twenty contributing chromosomal regions have been identified by linkage studies. On the other hand, mutations in several genes such as TWIST and FGFR2 result in syndromic cranio-facial abnormalities of highly variable range.

Involvement of MET/TWIST/APC combination or the potential role of ossification factors in pediatric high-grade osteosarcoma oncogenesis.

Dysregulated cell growth or differentiation due to misexpression of developmental critical factors seems to be a decisive event in oncogenesis. As osteosarcomas are histologically defined by malignant osteoblasts producing an osteoid component, we prospected in pediatric osteosarcomas treated with OS94 protocol the genomic status of several genes implied in ossification processes. In 91 osteosarcoma cases, we focused on the analysis of the fibroblast growth factor receptors (FGFRs) TWIST, APC, and MET by allelotyping, real-time quantitative polymerase chain reaction, gene sequencing, and protein polymorphism study.

Tissue engineering of tooth crown, root, and periodontium.

Tissue engineering of teeth requires the coordinated formation of correctly shaped crowns, roots, and periodontal ligament. Previous studies have shown that the dental mesenchyme controls crown morphogenesis and epithelial histogenesis during tooth development in vivo, but little is known about the inductive potential of dissociated mesenchymal cells used in ex vivo cultures. A 2-step method is described in which, by using different types of reassociations between epithelial and mesenchymal tissues and/or cells from mouse embryos, reassociations were cultured in vitro before in vivo implantation.

Expression patterns of BMPRs in the developing mouse molar.

During development, Bone Morphogenetic Proteins (BMPs) can induce apoptosis, cell growth or differentiation. These different effects are mediated by dimers of two types of BMP-receptors (BMPRs). To identify the responding cells during tooth development and search for possible tissue-or stage-specificities in the receptors involved, the distribution patterns of BMPR-IA, -IB and -II were investigated in the mouse molar, from bud to bell stage.

Differential regulation of TIMP-1, -2, and -3 mRNA and protein expressions during mouse incisor development.

Tissue inhibitors of metalloproteinases (TIMPs) possess multiple functions, in addition to their matrix metalloproteinase (MMP) inhibitory activity. The continuously growing incisor of mouse possesses a stem cell compartment at the apical end of the epithelium (the apical loop) and thus provides an excellent tool to analyze the mechanisms of organogenesis and cytodifferentiation. To understand the functions of TIMPs in tooth development, we have analyzed the gene expression and protein localization of TIMP-1, -2, and -3 during mouse incisor development, from embryonic day 13 (E13) to postnatal day 3 (P3).

BBS8 is rarely mutated in a cohort of 128 Bardet-Biedl syndrome families.

BBS8 is one of the eight genes identified to date for Bardet-Biedl syndrome (BBS)-an autosomal recessive condition associated with retinitis pigmentosa, obesity, polydactyly, cognitive impairment and kidney failure. The identification of BBS8 gave the key to the pathogenesis of the condition as a primary ciliary disorder. To date, only three families mutated in the BBS8 gene have been reported.

Dental Epithelial Histomorphogenesis in vitro.

Recent developments in tooth-tissue engineering require that we understand the regulatory processes to be preserved to achieve histomorphogenesis and cell differentiation, especially for enamel tissue engineering. Using mouse first lower molars, our objectives were: (1) to determine whether the cap-stage dental mesenchyme can control dental epithelial histogenesis, (2) to test the role of the primary enamel knot (PEK) in specifying the potentialities of the dental mesenchyme, and (3) to evaluate the importance of positional information in epithelial cells. After tissue dissociation, the dental epithelium was further dissociated into individual cells, re-associated with dental mesenchyme, and cultured.

Frequent genomic abnormalities at TWIST in human pediatric osteosarcomas.

The identification of genes as markers for chromosome aberrations in specific tumors might facilitate oncogenesis mechanism comprehension, cancer detection, prediction of clinical outcomes, and response to therapy. Previous physiologic and oncologic data identified the TWIST gene as a marker for mesodermal derivative and bone tissue differentiation, but its contribution to bone malignancies has not been investigated. In the present study, search for genomic alterations in high-grade pediatric osteosarcomas was focused on the 7p21 region, and more specifically on the TWIST gene.

Testing for triallelism: analysis of six BBS genes in a Bardet-Biedl syndrome family cohort.

The phenotype of Bardet-Biedl syndrome (BBS) is defined by the association of retinitis pigmentosa, obesity, polydactyly, hypogenitalism, renal disease and cognitive impairement. The significant genetic heterogeneity of this condition is supported by the identification, to date, of eight genes (BBS1-8) implied with cilia assembly or function. Triallelic inheritance has recently been suggested on the basis of the identification of three mutated alleles in two different genes for the same patient.

[Update on Bardet-Biedl syndrome].

Until recently, Bardet-Biedl syndrome was considered as a classic autosomal recessive condition. The disorder is defined by the association of the following clinical features: retinitis pigmentosa, polydactyly, obesity, hypogonadism, and possible mental retardation. This syndrome leads to multiple handicaps (visual impairment, complications of obesity, kidney failure, endocrine dysfunction).

Dental epithelial histo-morphogenesis in the mouse: positional information versus cell history.

Reciprocal epithelial-mesenchymal interactions control odontogenesis and the cap stage tooth germ mesenchyme specifies crown morphogenesis. The aim of this work was to determine whether this mesenchyme could also control epithelial histogenesis. Dental mesenchyme and enamel organ were dissociated from mouse first lower molars at E14.

A new mouse limb mutation identifies a Twist allele that requires interacting loci on chromosome 4 for its phenotypic expression.

Pluridigite ( Pdt) is a semi-dominant mutation obtained after a mutagenesis experiment with ethyl-nitroso-urea (ENU). The mutant exhibits abnormal skeletal pattern formation characterized by the formation of extra digits (polydactyly) in the preaxial (anterior) part of the hindlimbs. The phenotype shows incomplete penetrance, depending on the genetic background.

Temporospatial gene expression and protein localization of matrix metalloproteinases and their inhibitors during mouse molar tooth development.

The gene expression and protein distribution of matrix metalloproteinase (MMP) -2, -9, membrane type-1 MMP (MT1-MMP), as well as of TIMP-1, -2, and -3 were analyzed during mouse molar development. Immunohistochemical data demonstrated that all the MMPs investigated were expressed in the dental epithelium and mesenchyme. In contrast, gene and protein expression analysis for TIMPs showed that they were differentially expressed.

Sporadic and familial blepharophimosis -ptosis-epicanthus inversus syndrome: FOXL2 mutation screen and MRI study of the superior levator eyelid muscle.

The analysis of the FOXL2 gene (3q23) in a series of two families and two sporadic cases affected with Blepharophimosis-Ptosis-Epicanthus Inversus Syndrome (BPES) is presented. This study detected two novel FOXL2 mutations (missence and nonsens mutations) and confirmed the recurrence of a previously described duplication. Magnetic Resonance Imaging (MRI) of the orbit, in one family, showed absence or hypotrophy of the eyelid superior levator muscle suggesting a possible role of FOXL2 in the development of this extra-ocular muscle.

Natural TWIST protein variants in a panel of eleven non-human primates: possible implications of TWIST gene-tree for primate species tree.

The twist gene is implied in head morphogenesis, as human patients heterozygous at TWIST and heterozygous M-twist mutant mice present similar cranial-facial abnormalities. M-twist and TWIST are respectively unique genes, coding for a B-HLH transcription factor. We identified twist coding sequences from 11 species representing 7 families of primates, report their conservation and genus-specific amino acid substitutions, and present a tentative gene-tree of these sequences.

Cell-cell and cell-matrix interactions during initial enamel organ histomorphogenesis in the mouse.

Relationships between cell-cell/cell-matrix interactions and enamel organ histomorphogenesis were examined by immunostaining and electron microscopy. During the cap-bell transition in the mouse molar, laminin-5 (LN5) disappeared from the basement membrane (BM) associated with the inner dental epithelium (IDE), and nondividing IDE cells from the enamel knot (EK) underwent a tooth-specific segregation in as many subpopulations as cusps develop. In the incisor, the basement membrane (BM) in contact with EK cells showed strong staining for LN5 and integrin alpha 6 beta 4.

Mouse Twist is required for fibroblast growth factor-mediated epithelial-mesenchymal signalling and cell survival during limb morphogenesis.

Mouse Twist is essential for cranial neural tube, limb and somite development. [Genes Dev. 9 (1995) 686].

Saethre-Chotzen syndrome: notable intrafamilial phenotypic variability in a large family with Q28X TWIST mutation.

Saethre-Chotzen syndrome is an autosomal dominant disease characterized by craniosynostosis, ptosis, and limb and external ear abnormalities. Variable expressivity is a well-known phenomenon in this disorder. A large Indian family has been recently identified as carrying a nonsense TWIST mutation (Q28 X) in 17 members, of whom 16 were examined in detail.