Faculty Bibliography

The KdpFABC complex (Kdp) functions as a K+ pump in Escherichia coli and is a member of the family of P-type ATPases. Unlike other family members, Kdp has a unique oligomeric composition and is notable for segregating K+ transport and ATP hydrolysis onto separate subunits (KdpA and KdpB, respectively). We have produced two-dimensional crystals of the KdpFABC complex within reconstituted lipid bilayers and determined its three-dimensional structure from negatively stained samples using a combination of electron tomography and real-space averaging. The resulting map is at a resolution of 2.4 nm and reveals a dimer of Kdp molecules as the asymmetric unit; however, only the cytoplasmic domains are visible due to the lack of stain penetration within the lipid bilayer. The sizes of these cytoplasmic domains are consistent with Kdp and, using a pseudo-atomic model, we have described the subunit interactions that stabilize the Kdp dimer within the larger crystallographic array. These results illustrate the utility of electron tomography in structure determination of ordered assemblies, especially when disorder is severe enough to hamper conventional crystallographic analysis

Psoriatic arthritis is a complex, chronic inflammatory disease with both skin and joint involvement. Clinical presentation varies considerably among patients and during the course of the disease. Assessment of patients for psoriatic arthritis requires careful attention to patient history, a focused physical examination, and inspection for characteristic radiographic changes. Although this disease was once thought to be a rare and mild form of arthritis, recent studies have shown that patients with psoriatic arthritis may develop significant disability, with up to 20% of cases demonstrating a rapidly progressive, debilitating clinical course. Orthopedic manifestations of the disease can be severe and can cause significant physical disability. Although surgical intervention for psoriatic arthritis is relatively uncommon, having an understanding of the assessment, available treatment options, and surgical considerations allows for improved outcome in the management of this complex patient population

Constrained acetabular liners can fail leading to recurrent dislocation. Failure can occur at any of the five possible interfaces: bone-acetabular shell, acetabular shell-constrained liner insert, constrained liner insert-bipolar head, bipolar head- femoral head and femoral head-trunion. We report a patient who presented with dissociation of the cemented Osteonics acetabular constrained liner (Stryker-Howmedica-Osteonics, Rutherford, New Jersey). The failure interface was at the factory pre-assembled constrained liner insert-bipolar head without any locking ring failure; instead there was deformation of the constrained liner insert's polyethylene rim, which facilitated dissociation. To our knowledge, there are no previous reports of such a failure mode pertaining to this type of constrained liner. Constrained acetabular liners are indicated during primary or revision total hip arthroplasty for patients who are at high risk for dislocations or who have had recurrent dislocations. Failure rates (typically recurrent dislocation) range from 4% to 29% at mid-term follow-up. The first report on the Osteonics acetabular constrained liner was published in 1994. Failures have been reported previously to occur at surgically controllable interfaces, such as the acetabular shell from the bony surface and the constrained liner insert from the acetabular metal shell, and have been attributable to excessive constraint or improper technique. All dissociations pertaining to factory-preassembled component interfaces have been attributed to breakage of the locking ring. This article presents the first case of disengagement of the tripolar constrained liner without disruption of the locking ring

The risk of atherosclerosis is inversely related to circulating levels of high density lipoprotein (HDL) cholesterol. Notably, in large-scale epidemiologic studies, this association is independent of plasma levels of low density lipoprotein cholesterol levels. Pharmacologic agents, such as fibrates and niacin that increase HDL cholesterol levels have been associated with decreased cardiovascular events and beneficial effects on the coronary and carotid arteries. Furthermore, there is evidence that the risk of restenosis following vascular interventions is inversely related to HDL levels. This review considers the available data from mainly murine models on potential mechanisms by which HDL may exert these anti-atherogenic effects, namely through its role in reverse cholesterol transport, its effects on endothelial cells, and its anti-inflammatory/anti-oxidant activities. In addition to discussing a role for HDL in retarding atherosclerosis progression, we will also review how HDL may play a role in promoting regression of atherosclerotic lesions

Prospective midbrain and cerebellum formation are coordinated by FGF ligands produced by the isthmic organizer. Previous studies have suggested that midbrain and cerebellum development require different levels of FGF signaling. However, little is known about the extent to which specific regions within these two parts of the brain differ in their requirement for FGF signaling during embryogenesis. Here, we have explored the effects of inhibiting FGF signaling within the embryonic mouse midbrain (mesencephalon) and cerebellum (rhombomere 1) by misexpressing sprouty2 (Spry2) from an early stage. We show that such Spry2 misexpression moderately reduces FGF signaling, and that this reduction causes cell death in the anterior mesencephalon, the region furthest from the source of FGF ligands. Interestingly, the remaining mesencephalon cells develop into anterior midbrain, indicating that a low level of FGF signaling is sufficient to promote only anterior midbrain development. Spry2 misexpression also affects development of the vermis, the part of the cerebellum that spans the midline. We found that, whereas misexpression of Spry2 alone caused loss of the anterior vermis, reducing FGF signaling further, by decreasing Fgf8 gene dose, resulted in loss of the entire vermis. Our data suggest that cell death is not responsible for vermis loss, but rather that it fails to develop because reducing FGF signaling perturbs the balance between vermis and roof plate development in rhombomere 1. We suggest a molecular explanation for this phenomenon by providing evidence that FGF signaling functions to inhibit the BMP signaling that promotes roof plate development

The expansion of gene therapy applications from inherited disorders to acquired conditions has been mirrored by an exponential rise in both experimental work and clinical trials. This review highlights current plastic surgical delivery systems and clinical applications for targeted gene therapy. We revisit some of the vectors used both experimentally and in clinical gene therapy trials, with an emphasis on developments in plastic surgical delivery systems resulting in improved targeting of therapeutic genes. In addition, we discuss a novel technique for the delivery of gene therapy using the ex vivo transduction of free flaps, developed in our laboratory. This delivery system achieves targeted high-level transgene expression with minimal demonstrable systemic toxicity. Advances in delivery systems are essential for translating basic research into clinical therapeutics

Fewer and fewer programs are training graduate students and postdoctoral fellows in the classical anatomical disciplines. Nonetheless, there remains a need at all levels of clinical and basic science education for skilled instructors of anatomy, histology, and embryology. Two sessions at the 2006 annual meeting of the American Association of Anatomists (AAA) explored whether a system of accreditation would benefit students, institutions, and training programs. Although the value of accreditation was controversial, three challenges for the various anatomical societies emerged from these discussions: (1) To identify the skills and knowledge that should be shared among all anatomists, and the more specific skills and knowledge needed for the diverse settings in which anatomists work. (2) To address the historical inattention of institutions to the training of educators. (3) To develop strategies to lobby institutions and national organizations to support the training and work of educators in the anatomical sciences. One approach to meeting these challenges would be to develop guidelines for training programs. These guidelines would help graduate students seek the training they need, provide institutions with a benchmark to assess or develop training programs, and provide the basis for focusing lobbying efforts targeted at institutions or existing accreditation bodies.

The adaptor protein SLP76 directs signaling downstream of the T cell receptor (TCR) and is essential for thymocyte development. SLP76 contains three N-terminal tyrosines that are critical for its function. To define the role of these residues in thymocyte development, we generated two lines of "knock-in" mice, one expressing a mutation in tyrosine 145 (Y145F) and a second harboring two point mutations at tyrosines 112 and 128 (Y112-128F). We show here that although thymocyte development requires both Y145- and Y112-128-generated signals, selection was more dependent upon Y145. Although several proximal TCR signaling events were defective in both mutant mice, phosphorylation of the guanine nucleotide exchange factor, Vav1, and activation of Itk-dependent pathways were differentially affected by mutations at Y112-128 and Y145, respectively. Analysis of mice expressing one Y145F and one Y112-128F allele revealed that these mutants could complement one another in trans, demonstrating cooperativity between two or more SLP76 molecules. Thus, the N-terminal tyrosines of SLP76 are required for thymocyte selection but can function on separate molecules to support TCR signaling.