The anatomy of the glenoid labrum: a comparison between human and dog.

The anatomy of the glenohumeral joint in humans is characterized by static and dynamic stabilizing structures. In particular the glenoid labrum (GL), the proximal attachment of the joint capsule and the lateral glenohumeral ligament, is an important passive stabilizer in the human shoulder. Although canine animal models are used frequently to investigate the complex biomechanics of the shoulder, few data regarding the microstructure of the canine GL are available. In this study, the anatomy of the canine GL and related structures (n = 20) was investigated and compared with the human anatomic situation (n = 36). In both human and beagle joints, the GL consisted of 3 zones-the transition zone, shifting zone, and meniscoid fold, but not all 3 zones were present in all joint segments from canine joints. In particular the peripheral parts of the GL showed rich vascularization in both species. The height and width of the GL in the histologic specimens indicated that the GL is of less importance as a passive stabilizer in dogs. Additional differences between the human and canine CL include the joint ligaments, tendons of the shoulder joint, and lack of rotator cuff. The structural and biomechanical characteristics of the joints of quadrupedal animals raise the question of their appropriateness for shoulder research.

Novel KRIT1 mutation and no molecular evidence of anticipation in a family with cerebral and spinal cavernous malformations.

BACKGROUND: Cerebral cavernous malformations (CCM) are vascular brain anomalies which can result in a variety of neurological symptoms. Familial CCM is inherited as an autosomal-dominant trait. There is one study in the literature which reports statistical evidence for anticipation in familial CCM. METHODS: We reevaluated the clinical course of the disease and performed molecular analyses in a previously described three-generation CCM family with apparent anticipation. RESULTS: Disease started at a younger age in each generation, strongly suggesting anticipation. The patient in generation I showed no clinical symptoms by the age of 68, whereas his son became wheelchair-bound at the age of 43 due to an intramedullary cavernous malformation at the thoracolumbar transition of the spinal cord. The patient in generation III had a pons hemorrhage at the age of 11 due to a large brainstem cavernoma. The hemorrhage caused facial palsy and hemiparesis, persisting as Millard-Gubler syndrome. Sequencing of KRIT1 identified a novel frameshift mutation in exon 15 (c.1561delC or p.Leu551X) which cosegregated with the phenotype. Flow-FISH analysis of granulocyte and lymphocyte telomere length showed that telomeres were longest in the youngest affected family member. CONCLUSIONS: We could not find any evidence for either of the two currently known molecular mechanisms for genetic anticipation (i.e., expansion of repetitive DNA elements or progressive telomere shortening) in this family. However, the family presented here raises the important question whether surveillance of CCM families with gradient-echo MRI should not only include the cerebrum, but the spinal cord as well.