123 resultados para 1-DIMENSIONAL CHAIN
Resumo:
Idiopathic scoliosis (IS) is a three-dimensional deformity of the spine and trunk. The most common form involve ado- lescents (AIS). The prevalence for AIS is 2-3% of the population, with 1 out of 6 patients requiring treatment of which 25% progress to surgery. Physical and rehabilitation medicine (PRM) plays a primary role in the so-called conservative treatment of adolescents with AIS, since all the therapeutic tools used (exercises and braces) fall into the PRM domain. According to a Cochrane systematic review there is evidence in favor of bracing, even if it is of low quality. Another shows that there is evidence in favor of exercises as an adjunctive treatment, but of low quality. Three meta-analysis have been published on bracing: one shows that bracing does not reduce surgery rates, but studies with bracing plus exercises were not included and had the highest effectiveness; another shows that full time is better than part-time bracing; the last focuses on observational studies following the SRS criteria and shows that not all full time rigid bracing are the same: some have the highest effectiveness, others have less than elastic and nighttime bracing. Two very important RCTs failed in recruitment, showing that in the field of bracing for scoliosis RCTs are not accepted by the patients. Consensuses by the international Society on Scoliosis Orthopedic and Rehabilitation Treatment (SOSORT) show that there is no agree- ment among experts either on the best braces or on their biomechanical action, and that compliance is a matter of clinical more than patients' behavior (there is strong agreement on the management criteria to achieve best results with bracing). A systematic review of all the existing studies shows effectiveness of exercises, and that auto-correction is the main goal of exercises. A systematic review shows that there are no studies on manual treatment. Research on conservative treat- ment of AIS has continuously decreased since the 1980s, but this trend changed only recently. The SOSORT Guidelines offers the actual standard of conservative care.
Resumo:
X-ray medical imaging is increasingly becoming three-dimensional (3-D). The dose to the population and its management are of special concern in computed tomography (CT). Task-based methods with model observers to assess the dose-image quality trade-off are promising tools, but they still need to be validated for real volumetric images. The purpose of the present work is to evaluate anthropomorphic model observers in 3-D detection tasks for low-contrast CT images. We scanned a low-contrast phantom containing four types of signals at three dose levels and used two reconstruction algorithms. We implemented a multislice model observer based on the channelized Hotelling observer (msCHO) with anthropomorphic channels and investigated different internal noise methods. We found a good correlation for all tested model observers. These results suggest that the msCHO can be used as a relevant task-based method to evaluate low-contrast detection for CT and optimize scan protocols to lower dose in an efficient way.
Resumo:
Hemoglobin and its structures have been described since the 1990s to enhance a variety of biological activities of endotoxins (LPS) in a dose-dependent manner. To investigate the interaction processes in more detail, the system was extended by studying the interactions of newly designed peptides from the γ-chain of human hemoglobin with the adjuvant monophosphoryl lipid A (MPLA), a partial structure of lipid A lacking its 1-phosphate. It was found that some selected Hbg peptides, in particular two synthetic substructures designated Hbg32 and Hbg35, considerably increased the bioactivity of MPLA, which alone was only a weak activator of immune cells. These findings hold true for human mononuclar cells, monocytes and T lymphocytes. To understand the mechanisms of action in more detail, biophysical techniques were applied. These showed a peptide-induced change of the MPLA aggregate structure from multilamellar into a non-lamellar, probably inverted, cubic structure. Concomitantly, the peptides incorporated into the tightly packed MPLA aggregates into smaller units down to monomers. The fragmentation of the aggregates was an endothermic process, differing from a complex formation but rather typical for a catalytic reaction.