The pelvic radiograph: lines, arcs and stripes.
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ABSTRACT:
SUBMITTER: Yeap PM
PROVIDER: S-EPMC8801847 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Pelvic sagittal inclination (PSI) is often evaluated in patients with hip pathology using lateral radiographs. However, it would be useful if PSI could be predicted from an anteroposterior radiograph since this film is ubiquitous in the evaluation of hip pathology. Herein, computer-modeling was applied to predict PSI from radiographic measurements assessed in the anteroposterior plane. Three-dimensional surface models of the pelvis, femur, and sacrum were reconstructed from computed tomography images of 50 women with hip dysplasia. This study cohort was selected as changes in PSI alter femoral head coverage, which is relevant to the diagnosis and treatment of hip dysplasia, a known cause of hip osteoarthritis. Five radiographic parameters commonly used to independently estimate PSI were evaluated after bone surfaces were projected to an anteroposterior plane, including the symphysis to sacrococcygeal joint distance (S-S distance), the pelvic foramen aspect ratio (PF ratio), the distance between the symphysis and a line connecting the femoral head centers (S-H distance), the sacro-femoral-pubic angle (SFP angle), and the pelvic vertical ratio (PVR). Regression models determined the ability of these parameters to predict PSI from -20° to 20° at 1° increment. All five parameters showed a strong correlation with the PSI (all r > 0.9). From the regression models, PSI was estimated with a median (maximum) absolute error of 3.6° (18.4°), 3.8° (17.7°), 5.2° (17.9°), 5.8° (28.8°), and 3.2° (23.5°) for the S-S distance, PF ratio, S-H distance, SFP angle, and PVR, respectively. The regression model for S-S distance had a mean slope of 2.18 that ranged from 1.98 to 2.41 when the sacrococcygeal joint was located superior to the symphysis. Results indicated that substantial errors occur when estimating the actual value of PSI from an anteroposterior radiograph. However, the change in PSI could be estimated from the S-S distance, which may aid surgeons to successfully increase head coverage through periacetabular osteotomy and to locate the acetabular cup in a functional position for total hip arthroplasty.
| S-EPMC7335595 | biostudies-literature
Project description:BackgroundSymptomatic leg length discrepancies (LLDs) are a significant complication after total hip arthroplasty. Many surgeons incorporate an intraoperative anteroposterior pelvis radiograph, to help prevent LLD; however, obtaining a high-quality radiograph is often difficult. The purpose of this study is to evaluate the accuracy and reliability of estimating LLD using different radiographic reference landmarks on suboptimal anteroposterior pelvis radiographs.Material and methodsWe obtained 2 pelvis Sawbones models with attached femurs and created a true shortening of the left femur of the experimental model by 7 mm. We then obtained a series of radiographs manipulating each model in standardized increments for a total of 66 different permutations of suboptimal radiographs. Each radiograph was evaluated for LLD by 2 separate orthopedic surgeons using reference lines bisecting the following anatomic landmarks: ischial tuberosities, acetabular teardrops, obturator foramina, sacroiliac joints, and the femoral heads, to the lesser trochanters. The accuracy and reliability of each line were then analyzed.ResultsThe obturator foramina line yielded the most reliable LLD estimates with an intraclass correlation coefficient of 0.939. This reference line was also the most accurate, with an average difference of 1.5 mm from the true LLD (P < .001), with 95% confidence to be within 1.8 mm.ConclusionThe obturator foramen reference line on an intraoperative radiograph is an accurate and reliable tool that should be utilized by joint replacement surgeons to estimate LLD even if the radiograph is suboptimal. This estimate is reliably reproduced among multiple observers and puts the estimate within 1.8 mm of a true LLD.
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Project description:Cytochrome oxidase (CO) reveals two compartments in V1 (patches and interpatches) and three compartments in V2 (thin, pale, and thick stripes). Previously, it was shown that thin stripes receive input predominantly from patches. Here we examined the projections to thick and pale stripes in macaques, revealed by retrograde tracer injections. After thick stripe injection, cells were distributed in layer 2/3 (67%), layer 4A (7%), layer 4B (23%), and layer 5/6 (2%). Except in layer 5/6, cells were concentrated in interpatches, with a stronger bias in layer 2/3 (84%) than in layer 4B (75%). After pale stripe injection, cells were found in layer 2/3 (87%), layer 4A (2%), layer 4B (10%), and layer 5/6 (2%). As for thick stripes, cells were located preferentially in interpatches in layer 2/3 (84%) and layer 4B (72%) but not in layer 5/6. Thick stripes received a higher proportion of their input from layer 4B, compared with pale stripes, consistent with reports that thick stripe neurons exhibit a pronounced layer 4B influence. This difference aside, both stripe types receive similar inputs from V1, at least in terms of cortical layer and CO compartment. This finding was bolstered by injecting different tracers into pale and thick stripes; 10-27% of cells were double labeled, with most located in interpatches. These results suggest that the distinctive receptive field properties of neurons in thick and pale stripes are generated by local V2 circuits, or by other specific projections, rather than by differing sources of laminar and compartmental input from V1.
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Project description:The availability of oxygen is a major environmental factor for many microbes, in particular for bacteria, such as Shewanella species, which thrive in redox-stratified environments. One of the best studied systems involved in mediating the response to changes in environmental oxygen levels is the Arc two-component system of Escherichia coli, consisting of the sensor kinase ArcB and the cognate response regulator ArcA. An ArcA ortholog was previously identified in Shewanella, and as in E. coli, Shewanella ArcA is involved in regulating the response to shifts in oxygen levels. Here, we identified the hybrid sensor kinase SO_0577, now designated ArcS, as the previously elusive cognate sensor kinase of the Arc system in S. oneidensis MR-1. Phenotypic mutant characterization, transcriptomic analysis, protein-protein interaction and phosphotransfer studies revealed that the Shewanella Arc system consists of the sensor kinase ArcS, the single phosphotransfer domain protein HptA, and the response regulator ArcA. Phylogenetic analysis suggests that HptA might be a relict of ArcB. Conversely, ArcS is substantially different with respect to overall sequence homologies and domain organization. Thus, we speculate ArcS might have adopted the role of ArcB after loss of the original sensor kinase, perhaps as a consequence of regulatory adaptation to a redox-stratified environment.
2010-03-25 | GSE21044 | GEO
Project description:Subduction-transform edge propagators are lithospheric tears bounding slabs and back-arc basins. The volcanism at these edges is enigmatic because it is lacking comprehensive geological and geophysical data. Here we present bathymetric, potential-field data, and direct observations of the seafloor on the 90?km long Palinuro volcanic chain overlapping the E-W striking tear of the roll-backing Ionian slab in Southern Tyrrhenian Sea. The volcanic chain includes arc-type central volcanoes and fissural, spreading-type centers emplaced along second-order shears. The volume of the volcanic chain is larger than that of the neighbor island-arc edifices and back-arc spreading center. Such large volume of magma is associated to an upwelling of the isotherms due to mantle melts upraising from the rear of the slab along the tear fault. The subduction-transform edge volcanism focuses localized spreading processes and its magnitude is underestimated. This volcanism characterizes the subduction settings associated to volcanic arcs and back-arc spreading centers.
| S-EPMC5682279 | biostudies-literature
Project description:The availability of oxygen is a major environmental factor for many microbes, in particular for bacteria, such as Shewanella species, which thrive in redox-stratified environments. One of the best studied systems involved in mediating the response to changes in environmental oxygen levels is the Arc two-component system of Escherichia coli, consisting of the sensor kinase ArcB and the cognate response regulator ArcA. An ArcA ortholog was previously identified in Shewanella, and as in E. coli, Shewanella ArcA is involved in regulating the response to shifts in oxygen levels. Here, we identified the hybrid sensor kinase SO_0577, now designated ArcS, as the previously elusive cognate sensor kinase of the Arc system in S. oneidensis MR-1. Phenotypic mutant characterization, transcriptomic analysis, protein-protein interaction and phosphotransfer studies revealed that the Shewanella Arc system consists of the sensor kinase ArcS, the single phosphotransfer domain protein HptA, and the response regulator ArcA. Phylogenetic analysis suggests that HptA might be a relict of ArcB. Conversely, ArcS is substantially different with respect to overall sequence homologies and domain organization. Thus, we speculate ArcS might have adopted the role of ArcB after loss of the original sensor kinase, perhaps as a consequence of regulatory adaptation to a redox-stratified environment. In the study presented, expression profiles of three independent replicates of Shewanella oneidensis MR-1 delta-arcS were compared to three independent replicates of Shewanella oneidensis MR-1 wild type cells. All samples were obtained from exponentially aerobically grown cells in LB
2010-06-05 | E-GEOD-21044 | biostudies-arrayexpress
Project description:In subduction zones, materials on Earth's surface can be transported to the deep crust or mantle, but the exact mechanisms and the nature of the recycled materials are not fully understood. Here, we report a set of migmatites from western Yangtze Block, China. These migmatites have similar bulk compositions as forearc sediments. Zircon age distributions and Hf-O isotopes indicate that the precursors of the sediments were predominantly derived from juvenile arc crust itself. Using phase equilibria modeling, we show that the sediments experienced high temperature-to-pressure ratio metamorphism and were most likely transported to deep arc crust by intracrustal thrust faults. By dating the magmatic zircon cores and overgrowth rims, we find that the entire rock cycle, from arc magmatism, to weathering at the surface, then to burial and remelting in the deep crust, took place within ~10 Myr. Our findings highlight thrust faults as an efficient recycling channel in compressional arcs and endogenic recycling as an important mechanism driving internal redistribution and differentiation of arc crust.
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