Orofacial Muscles: Embryonic Development and Regeneration after Injury

Orofacial congenital defects such as cleft lip and/or palate are associated with impaired muscle regeneration and fibrosis after surgery. Also, other orofacial reconstructions or trauma may end up in defective muscle regeneration and fibrosis. The aim of this review is to discuss current knowledge on the development and regeneration of orofacial muscles in comparison to trunk and limb muscles. The orofacial muscles include the tongue muscles and the branchiomeric muscles in the lower face. Their main functions are chewing, swallowing, and speech. All orofacial muscles originate from the mesoderm of the pharyngeal arches under the control of cranial neural crest cells. Research in vertebrate models indicates that the molecular regulation of orofacial muscle development is different from that of trunk and limb muscles. In addition, the regenerative ability of orofacial muscles is lower, and they develop more fibrosis than other skeletal muscles. Therefore, specific approaches need to be developed to stimulate orofacial muscle regeneration. Regeneration may be stimulated by growth factors such fibroblast growth factors and hepatocyte growth factor, while fibrosis may be reduced by targeting the transforming growth factor β1 (TGFβ1)/myofibroblast axis. New approaches that combine these 2 aspects will improve the surgical treatment of orofacial muscle defects

Demographic, clinical and antibody characteristics of patients with digital ulcers in systemic sclerosis: data from the DUO Registry

OBJECTIVES: The Digital Ulcers Outcome (DUO) Registry was designed to describe the clinical and antibody characteristics, disease course and outcomes of patients with digital ulcers associated with systemic sclerosis (SSc). METHODS: The DUO Registry is a European, prospective, multicentre, observational, registry of SSc patients with ongoing digital ulcer disease, irrespective of treatment regimen. Data collected included demographics, SSc duration, SSc subset, internal organ manifestations, autoantibodies, previous and ongoing interventions and complications related to digital ulcers. RESULTS: Up to 19 November 2010 a total of 2439 patients had enrolled into the registry. Most were classified as either limited cutaneous SSc (lcSSc; 52.2%) or diffuse cutaneous SSc (dcSSc; 36.9%). Digital ulcers developed earlier in patients with dcSSc compared with lcSSc. Almost all patients (95.7%) tested positive for antinuclear antibodies, 45.2% for anti-scleroderma-70 and 43.6% for anticentromere antibodies (ACA). The first digital ulcer in the anti-scleroderma-70-positive patient cohort occurred approximately 5 years earlier than the ACA-positive patient group. CONCLUSIONS: This study provides data from a large cohort of SSc patients with a history of digital ulcers. The early occurrence and high frequency of digital ulcer complications are especially seen in patients with dcSSc and/or anti-scleroderma-70 antibodies

Veranderungen im Desmodont nach experimenteller Bewung von Zahnen mit starken und schwachen kontinuierlichen Kraften bei Hunden der Rass Beagle.

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Retinoic acid signalling in the development of the epidermis, the limbs and the secondary palate

Retinoic acid (RA), the active derivative of vitamin A, is one of the major regulators of embryonic development, including the development of the epidermis, the limbs and the secondary palate. In the embryo, RA levels are tightly regulated by the activity of RA synthesizing and degrading enzymes. Aberrant RA levels due to genetic variations in RA metabolism pathways contribute to congenital malformations in these structures. In vitro and in vivo studies provide considerable evidence on the effects of RA and its possible role in the development of the epidermis, the limbs and the secondary palate. In conjunction with other regulatory factors, RA seems to stimulate the development of the epidermis by inducing proliferation and differentiation of ectodermal cells into epidermal cells. In the limbs, the exact timing of RA location and level is crucial to initiate limb bud formation and to allow chondrogenesis and subsequent osteogenesis. In the secondary palate, the correct RA concentration is a key factor for mesenchymal cell proliferation during palatal shelf outgrowth, elevation and adhesion, and finally to allow bone formation in the hard palate. These findings are highly relevant to understanding the mechanism of RA signalling in development and in the aetiology of specific congenital diseases

The oxytalan fibre network in the periodontium and its possible mechanical function.

Contains fulltext : 109898.pdf (publisher's version ) (Closed access)The biomechanical character of the periodontal ligament (PDL) is crucial in its response to functional and orthodontic forces. Collagen has been the primary subject of investigations in this field. Several studies, however, indicate that oxytalan fibres, which belong to the elastic fibre family, also contribute to the biomechanical character and behaviour of the PDL. In order to elucidate this, we have evaluated the available literature on the oxytalan fibre network within the PDL and supra-alveolar tissues with respect to development, morphology and distribution, and response to mechanical stimulation. To this end, we have combined the classical histological studies with more recent in vitro studies. Oxytalan fibres develop simultaneously with the root and the vascular system within the PDL. A close association between oxytalan fibres and the vascular system also remains later in life, suggesting a role in vascular support. Mechanical loading of the PDL, through orthodontic force application, appears to induce an increase in the number, size, and length of oxytalan fibres. In line with this, in vitro stretching of PDL fibroblasts (PDLFs) results in an increased production of fibrillin, a major structural component of the microfibrils that make up oxytalan fibres. The available data suggest a mechanical function for oxytalan, but to date experimental data are limited. Further research is required to clarify their exact mechanical function and possible role in orthodontic tooth movement.01 augustus 201