PTEN tumor suppressor is frequently mutated in human cancers and is a negative regulator of PI3'K/PKB/Akt-dependent cellular survival. Investigation of the human genomic PTEN locus revealed a p53 binding element directly upstream of the PTEN gene. Deletion and mutation analyses showed that this element is necessary for inducible transactivation of PTEN by p53. A p53-independent element controlling constitutive expression of PTEN was also identified. In contrast to p53 mutant cell lines, induction of p53 in primary and tumor cell lines with wild-type p53 increased PTEN mRNA levels. PTEN was required for p53-mediated apoptosis in immortalized mouse embryonic fibroblasts. Our results reveal a unique role for p53 in regulation of cellular survival and an interesting connection in tumor suppressor signaling.

No abstract

Hip arthroscopy remains a useful surgical intervention for labral injuries. The literature has predominantly focused on structural and vascular considerations of the hip joint, with few studies examining the neurohistology of the surrounding periarticular tissues. We mapped and identified the periarticular neural anatomy, to identify the presence of sensory nerve fibres and mechanoreceptors within the hip joint. Eight human cadaveric hips were dissected into a total of ten specimens per hip. Histological staining was used to identify neural structures taken from the superolateral, anterior, inferior, and posterior positions of the hip joint. The frozen sections were analyzed by light microscopy to calculate relative concentrations of mean neural fibres per high power field (mnf/hpf). Neural end organs were found in the hip capsule, acetabular labrum, ligamentum teres and transverse acetabular ligament. The highest levels of mechanoreceptors were found in the superolateral aspect of the hip capsule (9.6 mnf/hpf). The labrum showed highest levels of sensory fibres (3.4 mnf/hpf) and mechanoreceptors (4.3mnf/hpf) within the anterior zone. Sensory fibres and mechanoreceptors densely populate the acetabular labrum, capsule and transverse acetabular ligament. The anterior zone of the labrum contained the highest relative concentration of sensory fibres, specifically Ruffini corpuscles.

The paired-like homeodomain (HD) protein Chx10 is distinguished by the presence of the CVC domain, a conserved 56 amino acid sequence C-terminal to the HD. In mammals, Chx10 is essential both for the proliferation of retinal progenitor cells and for the formation or survival of retinal bipolar interneurons. We describe the cloning and characterization of a mouse Chx10 homologue, Vsx1; phylogenetic analysis suggests that Vsx1 and its putative vertebrate orthologues have evolved rapidly. Vsx1 expression in the adult is predominantly retinal. Whereas Chx10 is expressed both in retinal progenitors in the developing eye and apparently in all bipolar cells of the mature retina, Vsx1 expression is first detected in the eye at postnatal day 5, where it is restricted to cone bipolar cells.

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Background A lateralized tibial tubercle is one potential cause of patellar instability. The tibial tubercle-trochlear groove (TT-TG) distance using CT is a reliable measure and considered the gold standard. Using MRI for this purpose has increased, although the reliability of doing so is not well studied. Questions/purposes We sought to (1) determine variability in the insertion of the patellar tendon relative to the tibial tubercle and whether this affects the measurement on MRI of the traditional TT-TG distance versus the functional patellar tendon-trochlear groove (PT-TG) distance, (2) determine the reliability of measuring the osseous TT-TG distance, (3) determine the reliability of measuring the soft tissue PT-TG distance, and (4) compare the reliabilities of using osseous (TT-TG) versus soft tissue (PT-TG) landmarks. Methods Four observers measured the TT-TG and the PT-TG distances of 50 MR images of knees obtained for any reason. Each observer repeated these measurements 30 days later. The interobserver and intraobserver reliabilities, measurements per observer that varied from the group mean by greater than 2 mm, and the limit of agreement were calculated. Results The TT-TG and PT-TG differed by as little as 0.11 mm and by as much as 4.18 mm with an average difference of 1.37 mm. The interobserver and intraobserver reliabilities were greater than 90% for the PT-TG and TT-TG distances. The PT-TG distance was less variable in that this measurement showed interobserver and intraobserver reliabilities of 0.977 and 0.972 respectively, versus 0.913 and 0.961 for the TT-TG measurement. Additionally, the PT-TG measurements resulted in a lower average difference to the mean for each observer, less number of knees per observer where the difference to the mean was greater than 2 mm, and improved limit of agreement. Conclusions The TT-TG and the PT-TG distances were not identical and differed by as much as 4.18 mm; as such they are not interchangeable when measuring this distance.

No abstract

The classic literature describes the transverse humeral ligament (THL) as a distinct anatomic structure with a role in biceps tendon stability; however, recent literature suggests that it is not a distinct anatomic structure. The purpose of this study was to evaluate the gross and microscopic anatomy of the THL, including a specific investigation of the histology of this ligament. Thirty frozen, embalmed cadaveric specimens were dissected to determine the gross anatomy of the THL. Seven specimens were evaluated histologically for the presence of mechanoreceptors and free nerve endings. Two tissue layers were identified in the area described as the THL. In the deep layer, fibers of the subscapularis tendon were found to span the bicipital groove with contributions from the coracohumeral ligament and the supraspinatus tendon. Superficial to this layer was a fibrous fascial covering consisting of distinct bands of tissue. Neurohistology staining revealed the presence of free nerve endings but no mechanoreceptors. This study's findings demonstrate that the THL is a distinct structure continuous with the rotator cuff tendons and the coracohumeral ligament. The finding of free nerve endings in the THL suggests a potential role as a shoulder pain generator.