Pax-1 in the development of the cervico-occipital transitional zone.

The Pax-1 gene has been found to play an important role in the development of the vertebral column. The cervico-occipital transitional zone is a specialized region of the vertebral column, and malformations of this region have frequently been described in humans. The exact embryonic border between head and trunk is a matter of controversy. In order to determine a possible role of Pax-1 in the development of the cervico-occipital transitional zone we studied the expression of this gene in a series of quail embryos and murine fetuses with in situ hybridization and immunohistochemistry. Pax-1 is expressed in all somites of the embryo, including the first five occipital ones. During embryonic days 3-5 the gene is down-regulated in the caudal direction within the first five somites, whereas more caudally Pax-1 is strongly expressed in the cells of the perinotochordal tube. In 5-day-old quail embryos, the cartilaginous anlage of the basioccipital bone has developed and ther is no more expression of Pax-1 in this region. The fusion of the dens axis with the body of the axis also coincides with switching off of the Pax-1 gene. More caudally, the gene is continuously expressed in the intervertebral discs of murine embryos and therefore seems to be important for the process of resegmentation. Quail embryos do not possess permanent intervertebral discs. ¿Hyper-¿ or ¿hyposegmentation¿ defects may be explained by an over- or under-expression of Pax-1 during development. We also reinvestigated the border between the head and trunk in chick embryos by performing homotopical grafting experiments of the 5th somite between chick and quail embryos.

The GAGs of the bone: a study on human calva.

The glycosaminoglycans of the human bone are Chondroitin-4 sulfate, Chondroitin-6 sulfate and Keratosulfate. Their quantity presents variations with ageing. The Keratosulfate shows a prevalent localisation in the bone matrix just around the osteocytes.

Elevated levels of transforming growth factors beta 2 and beta 3 in lambdoid sutures from children with persistent plagiocephaly.

OBJECTIVE: To analyze the pertinent history and physical findings specific to the subset of patients with a progressive posterior skull deformity, requiring surgery to correct their deformity. PATIENTS: Since the Academy of Pediatrics issued its recommendation on supine positioning of infants to prevent sudden infant death syndrome (SIDS) in 1992, 73 children have presented to the University of Virginia Craniofacial Anomalies Clinic with posterior-skull deformities. The majority were successfully managed with conservative therapy, but in six patients, the deformity was severe and persistent, requiring surgical correction. All six children were older (7.5-12 mo), presenting with more severe morphologic appearances and a higher incidence of associated neurodevelopmental delay. Three had family backgrounds of isolated craniosynostosis. METHODS: Characteristics of these patients were examined to determine why they may have differed from those that responded to conservative management. Immunohistochemical staining of their lambdoid sutures was performed. RESULTS: Significantly increased staining for TGF-beta 2 and TGF-beta 3, potent stimulators of bone cell growth and differentiation, was seen in all 'affected' sutures from the flattened side of the skull, compared to unaffected sutures from the protruding side of the skull-a pattern similar to that seen during normal bony obliteration of calvarial sutures. CONCLUSION: The majority of patients with posterior plagiocephaly associated with positioning responded to conservative management, while a small subset of patients with persistent posterior skull deformation required surgical intervention. A genetic basis for the latter patients' persistent plagiocephaly, rather than positioning, cannot be ruled out. Genetics, prolonged external pressure against the sutures, or a combination of these factors may lead to permanently raised levels of growth factors in 'affected' sutures.