Correction of chin ptosis

Chin ptosis is described as a descent of the soft tissue from the symphyseal region to a position under the lower contour of the mandible. Given its multifactorial causes, treatment must be determined on a patient-by-patient basis. While augmentation of the submental crease is a versatile option for the correction of chin ptosis, this only corrects the soft tissue component. A technical modification to treat dynamic chin ptosis, associated with bone reduction in the mandibular symphysis, is presented here.

Measuring the condylar unit in condylar hyperplasia: from the sigmoid notch or from the mandibular lingula?

The objective of this study was to determine, in patients with active unilateral condylar hyperplasia, which is the most reliable point to measure the length of the condylar unit: from the sigmoid notch or from the mandibular lingula to the condylar head. On cone beam computed tomography, an observational cross-sectional study was designed for 20 patients with active unilateral condylar hyperplasia. We measured and compared ramus length (affected and healthy sides) and condylar length (measured from the mandibular lingula and from the mandibular sigmoid notch) on both sides. The average of all the differences in ramus height (D.1) was 7.97mm; the average of all the differences in condylar heights measured from mandibular lingula (D.2) was 7.16mm, and measured from the sigmoid notch (D.3) was 4.89mm. No significant difference between D.1 and D.2 (P=0.818). There was a significant difference between D.1 and D.3 (P=0.005) and between D.2 and D.3 (P=0.0005). It can be concluded that the mandibular lingula is the lowest point of the condylar skeletal unit and is therefore a stable parameter to be used in patients with condylar hyperplasia. On the other hand, the sigmoidal notch is not a stable parameter in patients with asymmetry due to condylar hyperplasia.

A new way to anchor the external device in mandibular distraction: three case reports with a Pierre Robin sequence

Pierre Robin sequence is a pathology derived from alteration in the first and second branchial arch. Patients have breathing problems due to micrognathia and glossoptosis, causing severe upper airway obstruction. One surgical treatment is distraction osteogenesis. Three patients with Pierre Robin sequence (case 1, 3 months old; cases 2 and 3, 1 month old) with severe upper airway obstruction requiring mechanical ventilator assistance, underwent mandibular distraction osteogenesis prematurely with a new anchoring system, thus avoiding tracheostomy and its consequences. An intraoral approach was used to avoid scarring. A new anchoring device with transfixing Kirschner wire in the proximal (mandibular ramus) and distal segment (chin zone) was used. This diminishes the risk of distractor device displacement, guaranteeing optimal stability. A more anterior installation reduces the risk of damaging tooth buds in the mandibular body and the inferior alveolar nerve. The more anterior the fixation, the more horizontal the distraction vector becomes. The position and stability of the device are crucial. In these three patients the placement of two transfixing Kirschner wires using an intraoral approach showed good results and stability during the period of distraction and consolidation, with optimal results on the upper airway, avoiding tracheostomy.

Regeneration of transgenic plants by Agrobacterium-mediated transformation of somatic embryos of juvenile and mature Quercus robur

A protocol was developed for genetic transformation of somatic embryos derived from juvenile and mature Quercus robur trees. Optimal transformation conditions were evaluated on the basis of the results of transient GUS expression assays with five oak embryogenic lines and a strain of Agrobacterium tumefaciens (EHA105) harbouring a p35SGUSINT plasmid containing a nptII and a uidA (GUS) genes. For stable transformation, embryo clumps at globular/torpedo stages (4-10 mg) were inoculated with EHA105:p35SGUSINT bacterial cultures, cocultivated for 4 days and selected in proliferation medium with 75 mg/l of kanamycin. Putatively transformed masses appeared after 20-30 weeks of serial transfers to selective medium. Histochemical and molecular analysis (PCR and Southern blot) confirmed the presence of nptII and uidA genes in the plant genomes. Transformation efficiencies ranged from up to 2% in an embryogenic line derived from a 300-year-old tree, to 6% in a juvenile genotype. Twelve independent transgenic lines were obtained from these oak genotypes, and transgenic plantlets were recovered and acclimatized into the soil. This is the first demonstration of the production of transformed somatic embryos and regenerated plants from juvenile and mature trees of Q. robur and suggests the possibility of introducing other genetic constructions to develop trees that are tolerant/resistant to pathogens and/or biotic stresses.

Shoot apex explants for induction of somatic embryogenesis in mature Quercus robur L. trees

A procedure for inducing somatic embryos in shoot apex explants (2 mm) excised from shoot proliferation cultures established from adult oak trees (Quercus robur) was investigated. Embryogenesis was induced in shoot tip as well as leaf explants in three out of the five genotypes evaluated. Somatic embryos were formed by culture in induction medium supplemented with 21.48 muM naphthalene acetic acid and 2.22 muM benzyladenine for 8 weeks, and successive transfer of explants to expression media with a low concentration of growth regulators and without them. Both types of explants formed callus tissue from which somatic embryos developed, indicating indirect embryogenesis. Although the embryogenic frequencies were lower than 12%, it did not prevent the establishment of clonal embryogenic lines maintained by repetitive embryogenesis. Histological study confirmed an indirect somatic embryogenesis process from shoot tip explants, in which leaf primordia and the corresponding axial zones were involved in generating callus, whereas the apical meristem itself did not proliferate. The origin of embryogenic cells appeared to be associated with dedifferentiation of certain parenchymal cells in callus regions after transfer of explants to expression media without auxin. Division of embryogenic cells gave rise to proembryo aggregates of unicellular origin, although a multicellular origin from bulging embryogenic areas would also seem possible. Further development led to the formation of cotyledonary-stage somatic embryos and nodular embryogenic structures that may be considered as anomalous embryos with no clear bipolarity. Inducement of somatic embryos from explants isolated from shoot cultures ensures plant material all year round, thus providing a significant advantage over the use of leaf explants from field-grown trees.

Plant regeneration through somatic embryogenesis from tissues of mature oak trees: true-to-type conformity of plantlets by RAPD analysis

Somatic embryogenesis was induced in expanding leaf explants excised from epicormic shoots forced from branch segments taken at four different times of year from a mature oak (Quercus robur L.). Branch segments 2-4 cm in diameter produced most shoots when collected in March. Somatic embryos were induced on explants derived from branches of all collection dates, although collection in November seemed to afford the best results. Germination and conversion ability of embryos of embryogenic lines derived from six oak trees depended heavily on genotype, conversion rates ranging from 0 to 70%. RAPD analyses found no evidence of genetic variation either within or between the embryogenic lines established from three of these trees, or between these lines and the trees of origin, or between somatic embryo derived plantlets and the trees of origin. The embryogenic system used in this study appears to be suitable for true-to-type clonal propagation of mature oak genotypes.