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A hallmark of osteoarthritis (OA) is cartilage degeneration, which has been previously correlated with dramatic increases in inflammatory enzymes. Specifically, interleukin-1β (IL-1β) and subsequent upregulation of nuclear factor kappa B (NF-κB) is implicated as an important player in the development of posttraumatic osteoarthritis (PTOA). Alpha 2-macroglobulin (A2M) can inhibit this inflammatory pathway, making it a promising therapy for PTOA. Herein, we demonstrate that A2M binds and neutralizes IL-1β, blocking downstream NF-κB-induced catabolism seen in in vitro. Human chondrocytes (cell line C28) were incubated with A2M protein and then treated with IL-1β. A2M was labeled with VivoTag™ 680 to localize the protein postincubation. The degree of binding between A2M and IL-1β was evaluated through immunoprecipitation (IP). Catabolic proteins, including IL-1β and NF-kB, were detected by Western blot. Pro-inflammatory and chondrocyte-related gene expression was examined by qRT-PCR. VivoTag™ 680-labeled A2M was observed in the cytoplasm of C28 human chondrocytes by fluorescence microscopy. IP experiments demonstrated that A2M could bind IL-1β. Additionally, western blot analysis revealed that A2M neutralized IL-1β and NF-κB in a dose-dependent manner. Moreover, A2M decreased levels of MMPs and TNF-α and increased the expression of cartilage protective genes Col2, Type2, Smad4, and aggrecan. Mostly importantly, A2M was shown to directly neutralize IL-1β to downregulate the pro-inflammatory responses mediated by the NF-kB pathway. These results demonstrate a mechanism by which A2M reduces inflammatory catabolic activity and protects cartilage after joint injury. Further in vivo studies are needed to fully understand the potential of A2M as a novel PTOA therapy.

Background: Lubricin, or proteoglycan 4 (PRG4), is a glycoprotein responsible for joint boundary lubrication. PRG4 has been shown previously to be down-regulated after traumatic joint injury such as a meniscal tear. Preliminary evidence suggests that intra-articular injection of PRG4 after injury will reduce cartilage damage in rat models of surgically induced posttraumatic osteoarthritis. Objective: To determine the efficacy of intra-articular injection of full-length recombinant human lubricin (rhPRG4) for reducing cartilage damage after medial meniscal destabilization (DMM) in a preclinical large animal model. Study Design: Controlled laboratory study. Methods: Unilateral DMM was performed in 29 Yucatan minipigs. One week after DMM, animals received 3 weekly intra-articular injections (3 mL per injection): (1) rhPRG4 (1.3 mg/mL; n = 10); (2) rhPRG4+hyaluronan (1.3 mg/mL rhPRG4 and 3 mg/mL hyaluronan [~950 kDA]; n = 10); and (3) phosphate-buffered saline (PBS; n = 9). Hindlimbs were harvested 26 weeks after surgery. Cartilage integrity was evaluated by use of macroscopic (India ink) and microscopic (safranin O–fast green and hematoxylin and eosin) scoring systems. Secondary outcomes evaluated via enzyme-linked immunosorbent assay (ELISA) included PRG4 levels in synovial fluid, carboxy-terminal telepeptide of type II collagen (CTX-II) concentrations in urine and serum, and interleukin 1β (IL-1β) levels in synovial fluid and serum. Results: The rhPRG4 group had significantly less macroscopic cartilage damage in the medial tibial plateau compared with the PBS group ( P = .002). No difference was found between the rhPRG4+hyaluronan and PBS groups ( P = .23). However, no differences in microscopic damage scores were observed between the 3 groups ( P = .70). PRG4 production was elevated in the rhPRG4 group synovial fluid compared with the PBS group ( P = .033). The rhPRG4 group presented significantly lower urinary CTX-II levels, but not serum levels, when compared with the PBS ( P = .013) and rhPRG4+hyaluronan ( P = .011) groups. In serum and synovial fluid, both rhPRG4 ( P = .006; P = .017) and rhPRG4+hyaluronan groups ( P = .009; P = .03) presented decreased IL-1β levels. Conclusion: All groups exhibited significant cartilage degeneration after DMM surgery. However, animals treated with rhPRG4 had the least amount of cartilage damage and less inflammation, providing evidence that intra-articular injections of rhPRG4 may slow the progression of posttraumatic osteoarthritis. Clinical Relevance: Patients with meniscal trauma are at high risk for posttraumatic osteoarthritis. This study demonstrates that an intra-articular injection regimen of rhPRG4 may attenuate cartilage damage after meniscal injury.

Background context Although the New Zealand White (NZW) rabbit model has been increasingly used for spinal fusion research, reported complication rates have been as high as 23%. The substantial animal morbidity and mortality associated with the model makes experimentation inefficient and can lead to faulty data analysis. Operative complications are in part the result of suboptimal execution of the experimental protocol. Purpose To describe an experimental protocol for posterolateral intertransverse lumbar arthrodesis in the NZW rabbit and to analyze the effect of the protocol on the complication rate of this model. Study design/setting This is a descriptive analysis of the surgical technique (and related complications) used for posterolateral spinal arthrodesis in the NZW rabbit model. This study was performed at a university research facility. Methods The complications of posterolateral intertransverse lumbar arthrodesis in the NZW rabbit were analyzed before and after instituting a refined experimental protocol. Results A total of 77 NZW rabbits underwent a posterolateral lumbar arthrodesis. In the first 48 animals (Group A) complications occurred at a rate of 26% and included anesthetic demise, nerve palsies, wound infections or seromas and fusion of the wrong level. After the institution of a refined experimental protocol, there were no complications in a second group of 29 rabbits (Group B). Conclusions Adherence to a precise experimental protocol for posterolateral lumbar arthrodesis can minimize complications, thereby enhancing the NZW rabbit as a cost-effective and accurate animal model for spinal fusion research.

Proton Computed Tomography (pCT) is being developed in support of proton therapy and treatment planning. The aim of pCT, to reconstruct an accurate map of the stopping power (S.P.) in a phantom and, in the future, in patients, is being pursued with a diverse list of detector systems, using the entire arsenal of tracking and energy detectors developed for High Energy Physics (HEP). The first radiographs and 3D images are being reconstructed with prototype detectors, which will be described. Most of the existing systems are being upgraded to higher proton fluxes to reduce the scanning time.

CLINICAL application of protons was first suggested over 60 years ago [9]. Proton radiation can deliver high doses of radiation to tumors or other targets close to critical structures, and thus is vitally important for modern 3D conformal radiation therapy. Currently proton dose calculations rely on x-ray computed tomography (CT), which limits their accuracy due to the physical interaction differences of protons and x-rays. To gain the maximum benefit from proton therapy, proton computed tomography (pCT) offers the opportunity to more accurately plan proton doses and to verify the correct proton beam delivery in the treatment position. This is accomplished by choosing the proton energy sufficiently high to penetrate the patient and by reconstructing density values based on energy loss measurements [1]. As an additional advantage, pCT achieves similar density resolution with lower dose than x-ray CT, because each proton is tracked individually. Despite these advantages, a fully operational pCT system does currently not exist, in part, related to the large amount of proton and object data that need to be acquired and reconstructed, respectively. Preliminary work in proton CT over the last several years has centered on the most likely path formalism [8], image reconstruction [6], [3], [4], [5], and basic design of a system [7]. A vital step in the reconstruction of a pCT image is the calculation of the integral relative electron densities, which must be known for each of the proton histories. The number of histories can run into the hundreds of millions. Efficient calculation is important if the overall clinical goal of a pCT reconstruction in 5 minutes is to be achieved. Figure 1 shows the complete path of the proton histories through the image reconstruction process. This paper will focus on the hardware acceleration of the integral relative electron density calculation. The integral relative electron density requires the incoming and outgoing energies of the protons being tracked, which is given by the detectors. These values are not used in the iterative reconstruction process for reconstructing the image. Rather, they are calculated before the reconstruction iterations and stored with their corresponding proton history data.

Background: Distraction osteogenesis creates a challenging bone-healing environment with protracted demand for cells of the osteoblast lineage. Platelet-derived growth factor-BB (PDGF-BB) is an osteoblast mitogen and chemotaxin that has been shown to accelerate and/or enhance bone-healing in several preclinical studies. The purpose of the present study was to determine whether recombinant human platelet-derived growth factor-BB (rhPDGF-BB) would have a similar effect on regenerate healing after distraction osteogenesis. Methods: Unilateral 7-mm mid-diaphyseal femoral lengthening procedures were performed in eighty-three male Sprague-Dawley rats that were separated into five experimental groups. During the distraction period (Days 7 to 28), each animal received a weekly 50-μL injection of either sodium acetate buffer, bovine collagen dissolved in sodium acetate buffer, or one of three concentrations of rhPDGF-BB (100, 300, or 1000 μg/mL) into the distraction site. Animals from each group were killed on Days 35, 42, 49, 56, and 63. Healing was assessed with biweekly serial radiographs, micro-computed tomography of the explanted bones, and histologic analysis. Results: rhPDGF-BB treatment significantly increased new-bone formation at the midconsolidation time points (Days 42, 49, and 56) as well as the union rate. On Day 49 regenerate bone volume was significantly greater in each of the three rhPDGF-BB-treated groups than in the controls (p < 0.05, p = 0.0002, and p < 0.05 for the 100, 300, and 1000 μg/mL rhPDGF-BB groups, respectively), whereas on Day 42 regenerate bone volume was significantly greater in the 300 and 1000 μg/mL rhPDGF-BB groups than in the controls (p = 0.0002 and p < 0.05, respectively) and on Day 56 regenerate bone volume was significantly greater in the 100 and 300 μg/mL rhPDGF-BB groups than in the controls (p < 0.05 and p < 0.0001, respectively). The overall union rate was 40.4% (nineteen of forty-seven) in the rhPDGF-BB-treated animals, compared with 4.5% (one of twenty-two) in the controls (p = 0.01). The radiographic and histologic results were consistent with new-bone formation as quantified by micro-computed tomography, although they were less definitive. Conclusions: The administration of exogenous rhPDGF-BB into the distraction site during diaphyseal distraction enhanced bone-healing in a rat model of distraction osteogenesis as evidenced by both increased regenerate new-bone formation and a higher union rate. Clinical Relevance: The ability of rhPDGF-BB to enhance healing in this model suggests that it may be able to shorten treatment time and to decrease the nonunion rate in the challenging healing environment created during distraction osteogenesis.

Determination of the Bragg peak position in proton therapy requires accurate knowledge of the electron density and ratio of effective atomic number and mass (Z/A) of the body tissues traversed. While the Z/A ratio is fairly constant for human tissues, the density of tissues varies significantly. One possibility to obtain accurate electron density information of tissues is to use protons of sufficient energy to penetrate the patient and measure their energy loss. From these transmission measurements, it is possible to reconstruct a three‐dimensional map of electron densities using algebraic techniques. The interest in proton computed tomography (pCT) has considerably increased in recent years due to the more common use of proton accelerators for cancer treatment world‐wide and a modern design concept based on current high‐energy physics technology has been suggested. This contribution gives a status update on the pCT project carried out by the pCT Collaboration, a group of institutions sharing interest and expertise in the development of pCT. We will present updated imaging data obtained with a small pCT prototype developed in collaboration with the Santa Cruz Institute of Particle Physics and installed on the proton research beam line at Loma Linda University Medical Center. We will discuss hardware decisions regarding the next‐generation pCT scanner, which will permit scanning of head‐sized objects. Progress has also been made in the formulation of the most likely path of protons through an object and parallelizable iterative reconstruction algorithms that can be implemented on general‐purpose commodity graphics processing units. Finally, we will present simulation studies for utilizing pCT technology for on‐line proton dose verification and tumor imaging with positron emission tomography (PET).

Although the New Zealand White (NZW) rabbit model has been increasingly used for spinal fusion research, reported complication rates have been as high as 23%. The substantial animal morbidity and mortality associated with the model makes experimentation inefficient and can lead to faulty data analysis. Operative complications are in part the result of suboptimal execution of the experimental protocol.To describe an experimental protocol for posterolateral intertransverse lumbar arthrodesis in the NZW rabbit and to analyze the effect of the protocol on the complication rate of this model.This is a descriptive analysis of the surgical technique (and related complications) used for posterolateral spinal arthrodesis in the NZW rabbit model. This study was performed at a university research facility.The complications of posterolateral intertransverse lumbar arthrodesis in the NZW rabbit were analyzed before and after instituting a refined experimental protocol.A total of 77 NZW rabbits underwent a posterolateral lumbar arthrodesis. In the first 48 animals (Group A) complications occurred at a rate of 26% and included anesthetic demise, nerve palsies, wound infections or seromas and fusion of the wrong level. After the institution of a refined experimental protocol, there were no complications in a second group of 29 rabbits (Group B).Adherence to a precise experimental protocol for posterolateral lumbar arthrodesis can minimize complications, thereby enhancing the NZW rabbit as a cost-effective and accurate animal model for spinal fusion research.

Five horses were experimentally exposed to equine herpesvirus 2 strain LK. Two young foals developed chronic pharyngitis (98 and 232 days, respectively). Growth characteristics, cytopathic effects (CPE), inclusion body formation, ether sensitivity, and immunofluorescent analysis indicated that the virus recovered from infected animals was a herpesvirus serologically identical with, or at least antigenically related to EHV-2 strain LK. No significant complement-fixing (CF) or virus-neutralizing (VN) antibody responses were observed in adult horses while both foals demonstrated a rise in CF antibody titer. One of the two foals demonstrated a rise in VN antibody only. The results suggest that EHV-2 virus induced chronic pharyngitis, primarily the result of lymphoid proliferation, with no overt clinical signs.