To date, 3D spine reconstruction from biplanar radiographs involves intensive user supervision and semi-automated methods that are time-consuming and not effective in clinical routine. This paper ...proposes a new, fast, and automated 3D spine reconstruction method through which a realistic statistical shape model of the spine is fitted to images using convolutional neural networks (CNN). The CNNs automatically detect the anatomical landmarks controlling the spine model deformation through a hierarchical and gradual iterative process. The performance assessment used a set of 68 biplanar radiographs, composed of both asymptomatic subjects and adolescent idiopathic scoliosis patients, in order to compare automated reconstructions with ground truths build using multiple experts-supervised reconstructions. The mean (SD) errors of landmark locations (3D Euclidean distances) were 1.6 (1.3) mm, 1.8 (1.3) mm, and 2.3 (1.4) mm for the vertebral body center, endplate centers, and pedicle centers, respectively. The clinical parameters extracted from the automated 3D reconstruction (reconstruction time is less than one minute) presented an absolute mean error between 2.8° and 4.7° for the main spinal parameters and between 1° and 2.1° for pelvic parameters. Automated and expert's agreement analysis reported that, on average, 89% of automated measurements were inside the expert's confidence intervals. The proposed automated 3D spine reconstruction method provides an important step that should help the dissemination and adoption of 3D measurements in clinical routine.
Challenging the generally accepted belief that the introduction of racial slavery to America was an unplanned consequence of a scarce labor market, Anthony Parent, Jr., contends that during a brief ...period spanning the late seventeenth and early eighteenth centuries a small but powerful planter class, acting to further its emerging economic interests, intentionally brought racial slavery to Virginia.Parent bases his argument on three historical developments: the expropriation of Powhatan lands, the switch from indentured to slave labor, and the burgeoning tobacco trade. He argues that these were the result of calculated moves on the part of an emerging great planter class seeking to consolidate power through large landholdings and the labor to make them productive. To preserve their economic and social gains, this planter class inscribed racial slavery into law. The ensuing racial and class tensions led elite planters to mythologize their position as gentlemen of pastoral virtue immune to competition and corruption. To further this benevolent image, they implemented a plan to Christianize slaves and thereby render them submissive. According to Parent, by the 1720s the Virginia gentry projected a distinctive cultural ethos that buffered them from their uncertain hold on authority, threatened both by rising imperial control and by black resistance, which exploded in the Chesapeake Rebellion of 1730.
Melt compounding was used to prepare conventional composites of montmorillonite clay and polyethylene (PE) as well as nanocomposites of exfoliated montmorillonite platelets dispersed in a maleated ...polyethylene (PE-
g-MAn) matrix. The extent of clay platelet exfoliation in the PE-
g-MAn nanocomposites was confirmed by X-ray diffraction and resulted in a significant reduction of the degree of crystallinity and increased polymer crystallization rates. Studies of non-isothermal crystallization kinetics suggested that the exfoliated clay promotes heterogeneous nucleation and two-dimensional crystallite growth.
PE/clay composites behaved in a similar manner as conventional macrocomposites, exhibiting modest increases in their rheological properties and Young's modulus. Conversely, the nanoscale dimensions of the dispersed clay platelets in the nanocomposites led to significantly increased viscous and elastic properties and improved stiffness. This was attributed to the high surface area between the polymer matrix and the exfoliated clay, which resulted in enhanced phase adhesion.
Purpose
Clinical assessment of immediate in-brace effect of braces designed using CAD/CAM and FEM vs. only CAD/CAM for conservative treatment of AIS, using a randomized blinded and controlled study ...design.
Methods
Forty AIS patients were prospectively recruited and randomized into two groups. For 19 patients (control group), the brace was designed using a scan of patient’s torso and a conventional CAD/CAM approach (CtrlBrace). For the 21 other patients (test group), the brace was additionally designed using finite element modeling (FEM) and 3D reconstructions of spine, rib cage and pelvis (NewBrace). The NewBrace design was simulated and iteratively optimized to maximize the correction and minimize the contact surface and material.
Results
Both groups had comparable age, sex, weight, height, curve type and severity. Scoliosis Research Society standardized criteria for bracing were followed. Average Cobb angle prior to bracing was 27° and 28° for main thoracic (MT) and lumbar (L) curves, respectively, for the control group, while it was 33° and 28° for the test group. CtrlBraces reduced MT and L curves by 8° (29 %) and 10° (40 %), respectively, compared to 14° (43 %) and 13° (46 %) for NewBraces, which were simulated with a difference inferior to 5°. NewBraces were 50 % thinner and had 20 % less covering surface than CtrlBraces.
Conclusion
Braces designed with CAD/CAM and 3D FEM simulation were more efficient and lighter than standard CAD/CAM TLSO’s at first immediate in-brace evaluation. These results suggest that long-term effect of bracing in AIS may be improved using this new platform for brace fabrication.
Trial registration
NCT02285621.
Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety ...of developmental and reproductive detrimental abnormalities in wildlife species and, potentially, in human. Many experimental and epidemiological data have reported that exposure of the developing fetus or neonate to environmentally relevant concentrations of some among these endocrine disrupters induces morphological, biochemical and/or physiological disorders in brain and reproductive organs, by interfering with the hormone actions. The impact of such exposures on the hypothalamic–pituitary–gonadal axis and subsequent sexual maturation is the subject of the present review. We will highlight epidemiological human studies and the effects of early exposure during gestational, perinatal or postnatal life in female rodents.
Beside its well-documented role in carcinogenesis, the function of p53 family has been more recently revealed in development and female reproduction, but it is still poorly documented in male ...reproduction. We specifically tested this possibility by ablating Mdm2, an E3 ligase that regulates p53 protein stability and transactivation function, specifically in Sertoli cells (SCs) using the AMH-Cre line and created the new SC-Mdm2(-/-) line. Heterozygous SC-Mdm2(-/+) adult males were fertile, but SC-Mdm2(-/-) males were infertile and exhibited: a shorter ano-genital distance, an extra duct along the vas deferens that presents a uterus-like morphology, degenerated testes with no organized seminiferous tubules and a complete loss of differentiated germ cells. In adults, testosterone levels as well as StAR, P450c17 (Cyp17a1) and P450scc (Cyp11a1) mRNA levels decreased significantly, and both plasma LH and FSH levels increased. A detailed investigation of testicular development indicated that the phenotype arose during fetal life, with SC-Mdm2(-/-) testes being much smaller at birth. Interestingly, Leydig cells remained present until adulthood and fetal germ cells abnormally initiated meiosis. Inactivation of Mdm2 in SCs triggered p53 activation and apoptosis as early as 15.5 days post conception with significant increase in apoptotic SCs. Importantly, testis development occurred normally in SC-Mdm2(-/-) lacking p53 mice (SC-Mdm2(-/-)p53(-/-)) and accordingly, these mice were fertile indicating that the aforementioned phenotypes are entirely p53-dependent. These data not only highlight the importance of keeping p53 in check for proper testicular development and male fertility but also certify the critical role of SCs in the maintenance of meiotic repression.
Double-β-decay involves the simultaneous conversion of two neutrons into two protons, and the emission of two electrons and two neutrinos; the neutrinoless process, although not yet observed, is ...thought to involve the emission of the two electrons but no neutrinos. The search for neutrinoless-double-β-decay probes fundamental properties of neutrinos, including whether or not the neutrino and antineutrino are distinct particles. Double-β-decay detectors are large and expensive, so it is essential to achieve the highest possible sensitivity with each study, and removing spurious contributions ('background') from detected signals is crucial. In the nEXO neutrinoless-double-β-decay experiment, the identification, or 'tagging', of the
Ba daughter atom resulting from the double-β decay of
Xe provides a technique for discriminating background. The tagging scheme studied here uses a cryogenic probe to trap the barium atom in a solid xenon matrix, where the barium atom is tagged through fluorescence imaging. Here we demonstrate the imaging and counting of individual barium atoms in solid xenon by scanning a focused laser across a solid xenon matrix deposited on a sapphire window. When the laser irradiates an individual atom, the fluorescence persists for about 30 seconds before dropping abruptly to the background level-a clear confirmation of one-atom imaging. Following evaporation of a barium deposit, the residual barium fluorescence is 0.16 per cent or less. Our technique achieves the imaging of single atoms in a solid noble element, establishing the basic principle of barium tagging for nEXO.
The timing of puberty has been mainly studied in females for several reasons, including the possible evaluation of a precise timer (i.e. menarcheal age) and concerns with respect to the high ...prevalence of precocity in females as opposed to males. Human evidence of altered female pubertal timing after exposure to endocrine disrupting chemicals (EDCs) is equivocal. Among the limiting factors, most studies evaluate exposure to single EDCs at the time of puberty and hardly assess the impact of lifelong exposure to mixtures of EDCs. Some rodent and ovine studies indicate a possible role of foetal and neonatal exposure to EDCs, in accordance with the concept of an early origin of health and disease. Such effects possibly involve neuroendocrine mechanisms because the hypothalamus is a site where homeostasis of reproduction, as well as control of energy balance, is programmed and regulated. In our previous studies, pulsatile gonadotrophin‐releasing hormone (GnRH) secretion control via oestrogen, glutamate and aryl hydrocarbon receptors was shown to be involved in the mechanism of sexual precocity after early postnatal exposure to the insecticide dichlorodiphenyltrichloroethane. Very recently, we have shown that neonatal exposure to the potent synthetic oestrogen diethylstilbestrol (DES) is followed by early or delayed puberty depending on the dose, with consistent changes in developmental increase of GnRH pulse frequency. Moreover, DES results in reduced leptin stimulation of GnRH secretion in vitro, an effect that is additive with prenatal food restriction. Thus, using puberty as an endpoint of the effects of EDC, it appears necessary to consider pre‐ and perinatal exposure to low doses and to pay attention to the other conditions of prenatal life, such as energy availability, keeping in mind the possibility that puberty could not only be advanced, but also delayed through neuroendocrine mechanisms.
Retrospective analysis of a prospective registry and surgeon survey.
To identify surgeon opinion on ideal practice regarding the timing of decompression/stabilization for spinal cord injury and ...actual practice. Discrepancies in surgical timing and barriers to ideal timing of surgery were explored.
Canada.
Patients from the Rick Hansen Spinal Cord Registry (RHSCIR, 2004-2014) were reviewed to determine actual timing of surgical management. Following data collection, a survey was distributed to Canadian surgeons, asking for perceived to be the optimal and actual timings of surgery. Discrepancies between actual data and surgeon survey responses were then compared using χ
tests and logistic regression.
The majority of injury patterns identified in the registry were treated operatively. ASIA Impairment Scale (AIS) C/D injuries were treated surgically less frequently in the RHSCIR data and surgeon survey (odds ratio (OR)= 0.39 and 0.26). Significant disparities between what surgeons identified as ideal, actual current practice and RHSCIR data were demonstrated. A great majority of surgeons (93.0%) believed surgery under 24 h was ideal for cervical AIS A/B injuries and 91.0% for thoracic AIS A/B/C/D injuries. Definitive surgical management within 24 h was actually accomplished in 39.0% of cervical and 45.0% of thoracic cases.
Ideal surgical timing for traumatic spinal cord injury (tSCI) within 24 h of injury was identified, but not accomplished. Discrepancies between the opinions on the optimal and actual timing of surgery in tSCI patients suggest the need for strategies for knowledge translation and reduction of administrative barriers to early surgery.
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