National Bone Health Alliance: an innovative public-private partnership improving America's bone health.

The U.S. National Bone Health Alliance (NBHA) is a public-private partnership launched in 2010 that brings together its 56 partners from the government, nonprofit, and for-profit sectors to collectively promote bone health and prevent disease; improve bone disease diagnosis and treatment; and enhance bone research, surveillance, and evaluation. NBHA is driven to achieve its 20/20 vision to reduce fractures 20 % by the year 2020 through projects including 2Million2Many, an osteoporosis awareness campaign; Fracture Prevention CENTRAL, an online resource center providing support to sites interested in launching a secondary fracture prevention program; bone turnover marker standardization project; and working groups in rare bone disease and the clinical diagnosis of osteoporosis. NBHA provides a platform to coordinate messaging among individuals and organizations on subjects important to bone health; pool funding and efforts around shared priorities; and work together towards the goals and recommendations of the National Action Plan on Bone Health.

Zirconium: biomedical and nephrological applications.

Recent years have witnessed a rapid increase in the use of zirconium (Zr)-containing compounds in artificial internal organs. Examples include dental implants and other restorative practices, total knee and hip replacement, and middle-ear ossicular chain reconstruction. In nephrological practice, Zr-containing sorbents have been used in hemofiltration, hemodialysis, peritoneal dialysis, and in the design and construction of wearable artificial kidneys. Zr compounds continue to be widely and extensively used in deodorant and antiperspirant preparations. In the public health arena, Zr compounds have been studied or used in controlling phosphorus pollution and in the reclamation of poison and bacteria-contaminated water. Experimental and clinical studies support the general consensus that Zr compounds are biocompatible and exhibit low toxicity. Reports on possible Zr-associated adverse reactions are rare and, in general, have not rigorously established a cause-and-effect relationship. Although publications on the use of Zr compounds have continued to increase in recent years, reports on Zr toxicity have virtually disappeared from the medical literature. Nevertheless, familiarity with, and continued vigilant monitoring of, the use of these compounds are warranted. This article provides an updated review on the biomedical use of Zr compounds.

A lipid-protein hybrid model for tight junction.

The epithelial tight junction (TJ) was first described ultrastructurally as a fusion of the outer lipid leaflets of the adjoining cell membrane bilayers (hemifusion). The discovery of an increasing number of integral TJ and TJ-associated proteins has eclipsed the original lipid-based model with the wide acceptance of a protein-centric model for the TJ. In this review, we stress the importance of lipids in TJ structure and function. A lipid-protein hybrid model accommodates a large body of information supporting the lipidic characteristics of the TJ, harmonizes with the accumulating evidence supporting the TJ as an assembly of lipid rafts, and focuses on an important, but relatively unexplored, field of lipid-protein interactions in the morphology, physiology, and pathophysiology of the TJ.

A peritoneal-based automated wearable artificial kidney.

Work on wearable kidneys has evolved around the technology of hemodialysis or hemofiltration, which call for continuous anticoagulation of the extracoporeal circulation and are encumbered with potential immunologic and non-immunologic complications of continuous blood-artificial membrane interactions. A peritoneal-based automated wearable artificial kidney (AWAK) requires no extracorporeal circulation and is therefore "bloodless." Because AWAK is designed to continuously regenerate and reuse the spent dialysate in perpetuity, it is also "waterless." A sorbent-based assembly regenerates both the aqueous and the protein components (AqC and PrC) of the spent dialysate, producing a novel, autologous protein-containing dialysate. The regenerated AqC has the same composition as the commercially available peritoneal dialysate, but contains bicarbonate instead of lactate and has a more physiological pH. The regenerated PrC is recycled back into the peritoneal cavity, thereby ameliorating or eliminating protein loss. Depending on the steady-state protein concentrations that can be achieved (under the condition of continuous dialysate regeneration and recycling), the PrC also has the potential of both augmenting ultrafiltration and mediating the removal of protein-bound toxins. Additional sorbents can be incorporated into AWAK for the removal of middle molecular weight uremic toxins. At a regeneration rate of 4 l/h, AWAK provides a dialysate flow of 96 l/day (8-12 times the current rate). Round-the-clock dialysis and ultrafiltration provide steady-state metabolic-biochemical and fluid balance regulation, thereby eliminating "shocks" of abrupt changes in these parameters that characterize the current dialytic modalities. Dialysis-on-the-go, made possible by AWAK's "wearability" and automation, frees end-stage renal failure patients from the servitude that is demanded by the current dialytic regimentations.

FDG-PET lymphoma demonstration project invitational workshop.

The proceedings of a workshop focusing on a project to evaluate the use of fluorodeoxyglucose-positron emission tomography (FDG-PET) as a tool to measure treatment response in non-Hodgkin lymphoma (NHL) are described. Sponsored by the Leukemia & Lymphoma Society, the Foundation of the National Institutes of Health, and the National Cancer Institute, and attended by representatives of the Food and Drug Administration, the Centers for Medicare and Medicaid Services, and scientists and clinical researchers from academia and the pharmaceutical and medical imaging industries, the workshop reviewed the etiology and current standards of care for NHL and proposed the development of a clinical trial to validate FDG-PET imaging techniques as a predictive biomarker for cancer therapy response. As organized under the auspices of the Oncology Biomarker Qualification Initiative, the three federal health agencies and their private sector and nonprofit/advocacy group partners believe that FDG-PET not only demonstrates the potential to be used for the diagnosis and staging of many cancers but in particular can provide an early indication of therapeutic response that is well correlated with clinical outcomes for chemotherapy for this common form of lymphoma. The development of standardized criteria for FDG-PET imaging and establishment of procedures for transmission, storage, quality assurance, and analysis of PET images afforded by this demonstration project could streamline clinical trials of new treatments for more intractable forms of lymphoma and other cancers and, hence, accelerate new drug approvals.

Tight junction biology and kidney dysfunction.

The epithelial tight junction (TJ) has three major functions. As a "gate," it serves as a regulatory barrier separating and maintaining biological fluid compartments of different composition. As a "fence," it generates and maintains the apicobasal polarity of cells that form the confluent epithelium. Finally, the TJ proteins form a trafficking and signaling platform that regulates cell growth, proliferation, differentiation, and dedifferentiation. Six examples are selected that illustrate the emerging link between TJ dysfunction and kidney disease. First, the glomerular slit diaphragm (GSD) is evolved, in part, from the TJ and, on maturation, exhibits all three functions of the TJ. GSD dysfunction leads to proteinuria and, in some instances, podocyte dedifferentiation and proliferation. Second, accumulating evidence supports epithelial-mesenchymal transformation (EMT) as a major player in renal fibrosis, the final common pathway that leads to end-stage renal failure. EMT is characterized by a loss of cell-cell contact and apicobasal polarity, which are hallmarks of TJ dysfunction. Third, in autosomal dominant polycystic kidney disease, mutations of the polycystins may disrupt their known interactions with the apical junction complex, of which the TJ is a major component. This can lead to disturbances in epithelial polarity regulation with consequent abnormal tubulogenesis and cyst formation. Fourth, evidence for epithelial barrier and polarity dysregulation in the pathogenesis of ischemic acute renal failure will be summarized. Fifth, the association between mutations of paracellin-1, the first TJ channel identified, and clinical disorders of magnesium and calcium wasting and bovine renal fibrosis will be used to highlight an integral TJ protein that can serve multiple TJ functions. Finally, the role of WNK4 protein kinase in shunting chloride across the TJ of the distal nephron will be addressed.

Annexin A2 heterotetramer: role in tight junction assembly.

The tight junction has been characterized as a domain of focal fusions of the exoplasmic leaflets of the lipid bilayers from adjacent epithelial cells. Approximating membranes to within fusion distance is a thermodynamically unfavorable process and requires the participation of membrane-bridging or -fusion proteins. No known tight junction protein exhibits such activities. Annexin A2 (A2), in particular its heterotetramer (A2t), is known to form junctions between lipid bilayer structures through molecular bridging of their external leaflets. We demonstrate abundant A2 expression in Madin-Darby canine kidney II monolayers by two-dimensional gel electrophoresis. Confocal immunofluorescence microscopic analysis suggests the bulk of A2 is located along the apical and lateral plasma membrane in its tetrameric configuration, consisting of two A2 and two p11 (an 11-kDa calmodulin-related protein, S100A10) subunits. Immunocytochemistry and ultrastructural immunogold labeling demonstrate colocalization of the A2 subunit with bona fide tight junction proteins, zonula occludens-1, occludin, and claudin-1, at cell-cell contacts. The extracellular addition of a synthetic peptide, targeted to disrupt the binding between A2 and p11, completely aborts tight junction assembly in calcium chelation studies. We propose A2t as a member of a new class of tight junction proteins responsible for the long-observed convergence of adjacent exoplasmic lipid leaflets in tight junction assembly.