Journal of craniofacial genetics and developmental biology. Supplement最新文献

Mean plasma corticosterone levels of A/J mice rise from nonpregnant levels of 20.4 micrograms % to 40.6 micrograms % on day 11 and 167.11 micrograms % on day 14 of pregnancy. These changes in mean steroid levels are associated with proportionally increased diurnal swings. This suggests that the control mechanisms for diurnal swings respond in a proportional, rather than an absolute, way in regulating plasma hormone levels. Large diurnal hormone swings may be teratogenic or facilitate teratogenesis. The rules of receptor physiology may have wide application to the understanding of teratogenic risk.

The professional career of Samuel Pruzansky was intimately related to the development and success of the world's first Center for Craniofacial Anomalies (CCFA) at the University of Illinois-Chicago. Pruzansky conceived of the idea, officiated at the birth, and presided over the growth of this Center.

Velopharyngeal inadequacy in the absence of overt cleft palate may be due to any one, of any combination, of the following: intraorally visible stigmata associated with submucous defects (any combination of bifid uvula, muscular diastasis of the soft palate, bony defect of the hard palate); "occult" anatomical defects of the levator palatini or musculus uvulae, detectable only by nasopharyngoscopy or by operative dissection; anatomic disproportion between the size of the nasopharynx and the length of the hard and/or soft palate; mechanical interference with motion of the velopharyngeal system occurring as a result of scarring or contracture, and possibly as a result of interposition of the upper poles of the faucial tonsils between the velum and the posterior pharyngeal wall; a wide variety of neuromotor deficits, either congenital or acquired, causing reduced and/or incoordinated movement of the velopharyngeal musculature; a learning error of unknown origin which results in velopharyngeal inadequacy only on specific phonemes with all other pressure consonants emitted orally. Submucous defects of the secondary palate do not necessarily produce velopharyngeal inadequacy. Thus, our estimates of both the incidence of submucous defects and of the frequency of genes for clefting in any given population are undoubtedly low. Finally, "stress velopharyngeal inadequacy" in wind instrument players has been linked to a variety of anatomic findings and is not necessarily accompanied by velopharyngeal inadequacy in speech. This paper will review the historic aspects of velopharyngeal inadequacy and will discuss and analyze the causes outlined above.

The mouse strain CL/Fr has been produced by selection for high frequency of cleft lip. It is also sensitive to induction of cleft palate by glucocorticoids, as are its A strain relatives. "Star" strain is free of spontaneous clefts, and is resistant to glucocorticoid teratogenic effects. CL/Fr is also sensitive to toxic effects (80% death at 25 mg/kg) of diphenylhydantoin (DPH), whereas Star is not. Reciprocal crosses between CL/Fr and Star parents were followed for three generations of back-crossing to CL/Fr, with treatment by chronic subcutaneous (SC) DPH injection (20 mg/kg daily from day 0 of pregnancy). Two patterns of response were observed for facial clefts. Primary palate clefts (CL, CLP, lip scars) were not affected by DPH treatment, and showed regression on % CL/Fr genome suggestive of a two- or three-locus recessive effect with the sensitive alleles from CL/Fr. Secondary palate clefts and open eyelids, considered as a group as relatively late developmental defects, showed a pattern suggestive of a dominant gene which increases risk of malformation in DPH-treated embryos, expressed in the crosses, but not in the absence of treatment or in the presence of the full "Star" genome.

Studies of longitudinal cephalometric radiographs are presented for several patients with condylar fracture or hemifacial microsomia to illustrate condylar regeneration, presumably under functional influences. Implications of new condylar development and growth to facial and mandibular symmetry are presented. Clinical implications are introduced and the hypothesis of necessity of function for maintenance of relative facial symmetry is considered.

Case reports provide insights into fundamental mechanisms and also assist clinicians in treatment of similarly affected patients [Pruzansky, 1976]. The present investigation examines the natural history of the macroglossia associated with a case of Beckwith-Wiedemann syndrome (BWS) and its influence on dentofacial development. Facial skeletal growth and tongue size were assessed by analyzing cephalometric radiographs from age 2 months to 7.5 years. The data were compared with cephalometric norms and new normative data derived from 13 patients with cleft lip. The major influence of the macroglossia was protrusion of dentoalveolar structures, particularly in the lower jaw. This resulted in an anterior cross-bite in the primary dentition. In addition, an abnormally obtuse gonial angle was observed increasing the effective length of the mandible. Tongue size in BWS was generally greater than the norm, but the increase with age paralleled the mean growth curve of the tongue in the control. Over time the base of the tongue became longer and the hyoid bone moved posteriorly and inferiorly, allowing for accommodation of the tongue within the oral cavity. The changes in tongue shape and dentofacial morphology support the position that early partial glossectomy should be delayed or abandoned. In cases where tongue reduction is considered necessary, the new cephalometric normative data on tongue size provided herein can be used to establish objective criteria for such surgery.

The present report aims to contribute to our understanding of craniofacial development in plagiocephaly. A previously unreported dry skull with plagiocephaly and two clinical cases with unoperated plagiocephaly are presented. The clinical cases were followed longitudinally with roentgencephalometry in lateral, frontal, and axial projections. In addition, in one of the cases, electromyographic analysis of the temporal, masseter, sternomastoid, and trapezius muscles was carried out. The dry skull revealed premature closure of the sphenofrontal suture in addition to the coronal suture. Furthermore, severe asymmetry of the cranial base and mandible was observed. The clinical cases revealed a similar marked asymmetry of the cranial base. Mandibular asymmetry was observed to develop in early infancy secondary and compensatory to the primary asymmetry of the cranial base. The electromyographic examination revealed that the muscles of mastication were less developed on the affected side. Furthermore, the analysis of the muscles of the neck would seem to indicate that the patient compensated for her cranial base asymmetry and lateral deviation of the orbital axis on the affected side by rotating the head to the opposite side to secure binocular vision. Based on these findings, it would seem pertinent to consider early surgical release of the sutures of the calvaria and cranial base in plagiocephaly to prevent asymmetric facial development.

A computerized craniofacial patient record reinforces the link between clinical research and the treatment process. The availability of microcomputers and appropriate software has made it feasible for most craniofacial groups to organize patient data for easy retrieval and analysis. Selection of the computer system and programs follows careful planning and systematic delineation of the desired functions of the system. An example of a working computerized craniofacial patient record system is described.

The core problem in craniofacial development is regional specification of cell-specific gene expression. Regional specification is also referred to as pattern formation or spatial organization. During early embryogenesis, regional specification is possibly operant following blastula, and is apparent during gastrulation and thereafter during embryonic and fetal stages of development. Current interdisciplinary approaches toward understanding embryonic development incorporate a number of scientific approaches including those of recombinant DNA technology. Three major advances have significantly enhanced the utility of so-called "genetic engineering," including the discovery of restriction nuclease enzymes that cleave DNA sequences at specific sites; the discovery of DNA ligase enzymes that facilitate ligation and annealing of DNA sequences to one another, so as to facilitate the joining of foreign DNA sequences with host DNA; and the discovery of effective techniques for the introduction of foreign DNA sequences into previously refractory organisms. The present discussion analyzes the problem of regional specification of ameloblast-specific gene expression as a paradigm for utilizing recombinant DNA technology in studies of normal and abnormal craniofacial development.