Implementation of a Software Distribution Intervention to Improve Workload Balance in an Academic Pediatric Radiology Department

Journal of Digital Imaging - In our pediatric radiology department, radiographs (XR) are the shared responsibility of the body section and interpreted in addition to modality or site-specific...     

UHMWPE Wear Debris and Tissue Reactions Are Reduced for Contemporary Designs of Lumbar Total Disc Replacements

Background

Lumbar total disc replacement (L-TDR) is a procedure used to relieve back pain and maintain mobility. Contemporary metal-on-polyethylene (MoP) L-TDRs were developed to address wear performance concerns about historical designs, but wear debris generation and periprosthetic tissue reactions for these newer implants have not been determined.

Questions/purposes

The purpose of this study was to determine (1) whether periprosthetic ultrahigh-molecular-weight polyethylene (UHMWPE) wear debris and biological responses were present in tissues from revised contemporary MoP L-TDRs that contain conventional cores fabricated from γ-inert-sterilized UHMWPE; (2) how fixed- versus mobile-bearing design affected UHMWPE wear particle number, shape, and size; and (3) how these wear particle characteristics compare with historical MoP L-TDRs that contain cores fabricated from γ-air-sterilized UHMWPE.

Methods

We evaluated periprosthetic tissues from 11 patients who received eight fixed-bearing ProDisc-L and four mobile-bearing CHARITÉ contemporary L-TDRs with a mean implantation time of 4.1 and 2.7 years, respectively. Histologic analysis of tissues was performed to assess biological responses and polarized light microscopy was used to quantify number and size/shape characteristics of UHMWPE wear particles from the fixed- and mobile-bearing devices. Comparisons were made to previously reported particle data for historical L-TDRs.

Results

Five of seven (71%) fixed-bearing and one of four mobile-bearing L-TDR patient tissues contained at least 4 particles/mm² wear with associated macrophage infiltration. Tissues with wear debris were highly vascularized, whereas those without debris were more necrotic. Given the samples available, the tissue around mobile-bearing L-TDR was observed to contain 87% more, 11% rounder, and 11% less-elongated wear debris compared with tissues around fixed-bearing devices; however, there were no significant differences. Compared with historical L-TDRs, UHMWPE particle number and circularity for contemporary L-TDRs were 99% less (p = 0.003) and 50% rounder (p = 0.003).

Conclusions

In this preliminary study, short-term results suggest there was no significant influence of fixed- or mobile-bearing designs on wear particle characteristics of contemporary L-TDRs, but conventional UHMWPE has notably improved the wear resistance of these devices compared with historical UHMWPE.     

Rare complications of osteolysis and periprosthetic tissue reactions after hybrid and non-hybrid total disc replacement

Purpose

Few complications have been reported for lumbar total disc replacement (TDR) and hybrid TDR fixations. This study evaluated retrieved implants and periprosthetic tissue reactions for two cases of osteolysis following disc arthroplasty with ProDisc-L prostheses.

Methods

Implants were examined for wear and surface damage, and tissues for inflammation, polyethylene wear debris (polarized light microscopy) and metal debris (energy-dispersive X-ray spectroscopy).

Results

Despite initial good surgical outcomes, osteolytic cysts were noted in both patients at vertebrae adjacent to the implants. For the hybrid TDR case, heterotopic ossification and tissue necrosis due to wear-induced inflammation were observed. In contrast, the non-hybrid implant showed signs of abrasion and impingement, and inflammation was observed in tissue regions with metal and polyethylene wear debris.

Conclusions

In both cases, wear debris and inflammation may have contributed to osteolysis. Surgeons using ProDisc prostheses should be aware of these rare complications.

     

Copper is an endogenous modulator of neural circuit spontaneous activity

For reasons that remain insufficiently understood, the brain requires among the highest levels of metals in the body for normal function. The traditional paradigm for this organ and others is that fluxes of alkali and alkaline earth metals are required for signaling, but transition metals are maintained in static, tightly bound reservoirs for metabolism and protection against oxidative stress. Here we show that copper is an endogenous modulator of spontaneous activity, a property of functional neural circuitry. Using Copper Fluor-3 (CF3), a new fluorescent Cu⁺ sensor for one- and two-photon imaging, we show that neurons and neural tissue maintain basal stores of loosely bound copper that can be attenuated by chelation, which define a labile copper pool. Targeted disruption of these labile copper stores by acute chelation or genetic knockdown of the CTR1 (copper transporter 1) copper channel alters the spatiotemporal properties of spontaneous activity in developing hippocampal and retinal circuits. The data identify an essential role for copper neuronal function and suggest broader contributions of this transition metal to cell signaling.The foundation of cellular signal transduction relies on intricate chemical messenger systems that operate through the dynamic spatial and temporal regulation of elements, ions, and molecules. Nowhere is this concept better illustrated than in the brain, which extensively regulates fluxes of alkali and alkaline earth metals such as sodium, potassium, and calcium for a diverse array of signaling processes. Interestingly, the brain also accumulates among the highest levels of transition metals in the body (1–3), including redox-active copper. This high-redox metal load, in combination with the brain''s disproportionately active oxygen metabolism (4), makes this organ particularly susceptible to oxidative stress (4–6). As such, copper has been historically regarded as a tightly sequestered cofactor that must be buried within protein active sites to protect against reactive oxygen species generation and subsequent free radical damage chemistry. Indeed, elegant work continues to identify molecular players that maintain copper homeostasis in the brain (7, 8) and related organs (9–11), and loss of this strict regulation is implicated in neurotoxic stress (12–14) and a variety of neurodegenerative and neurodevelopmental disorders including Menkes (15, 16) and Wilson''s (17) diseases, familial amyotrophic lateral sclerosis (18, 19), Alzheimer''s (6, 14, 20–22) and Huntington''s (23, 24) diseases, and prion-mediated encephalopathies (14, 25, 26).Despite this long-held paradigm, emerging data also link pools of labile copper (defined as dynamic and loosely bound stores that undergo facile ligand exchange relative to static, tightly bound pools buried within protein active sites) to neurophysiology. Included are observations of ⁶⁴Cu efflux from stimulated neurons (12, 27), reversible trafficking of ATP7A from the perinuclear trans-Golgi to neuronal processes by NMDA receptor activation (12), effects of copper chelation on olfactory response to thiol odorants (28), and direct X-ray fluorescence imaging of copper translocation in neurons from somatic cell bodies to peripheral processes upon depolarization (29). Against this backdrop, we have initiated a program aimed at exploring the potential contributions of loosely bound forms of redox-active metals like copper in cell signaling. In this report, we identify a role for copper in the brain as a modulator of spontaneous activity, a fundamental property of developing neural circuits. The design and synthesis of Copper Fluor-3 (CF3), a fluorescent copper sensor based on a hydrophilic and tunable rhodol scaffold, along with Control Copper Fluor-3 (Ctrl-CF3), a matched control dye based on an identical fluorophore but lacking responsiveness to copper, enabled the visualization of loosely bound Cu⁺ in dissociated neurons and neural tissue by one- and two-photon microscopy. Disruption of Cu⁺ stores by acute application of a copper chelator or genetic knockdown of the copper ion channel CTR1 altered the spatiotemporal properties of spontaneous activity. In dissociated hippocampal cultures, these manipulations increased the correlation of spontaneous calcium transients, whereas in retina, both cell participation and frequency of correlated calcium transients increased.     

Efetividade da infiltração intra-articular guiada por imagem: comparação entre fluoroscopia e ultrassom

ObjectiveCompare the effectiveness of ultrasound and fluoroscopy to guide intra-articular injections (IAI) in selected cases.Material and methodsA prospective study in our outpatient clinics at the Rheumatology Division at Universidade Federal de São Paulo (UNIFESP), Brazil, was conducted to compare the short-term (4 weeks) effectiveness of ultrasound and fluoroscopy-guided IAI in patients with rheumatic diseases. Inclusion criteria were: adults with refractory synovitis undergo- ing IAI with glucocorticoid. All patients had IAI performed with triamcinolone hexaceton- ide (20 mg/ml) with varying doses according to the joint injected.ResultsA total of 71 rheumatic patients were evaluated (52 women, 44 whites). Mean age was 51.9 ± 13 years and 47 of them (66.2%) were on regular DMARD use. Analysis of the whole sample (71 patients) and hip sub-analysis (23 patients) showed that significant im- provement was observed for both groups in terms of pain (P < 0.001). Global analysis also demonstrated better outcomes for patients in the FCG in terms of joint flexion (P < 0.001) and percentage change in joint flexion as compared to the USG. Likert scale score analyses demonstrated better results for the patients in the USG as compared to the FCG at the end of the study (P < 0.05). No statistically significant difference between groups was observed for any other study variable.Discussion and conclusionImaging-guided IAI improves regional pain in patients with vari- ous types of synovitis in the short term. For the vast majority of variables, no significant difference in terms of effectiveness was observed between fluoroscopy and ultrasound- guided IAI.