RESUMO
Gut microbiota is a bridge between the metabolism and health state of the host,which plays a very important role in maintaining homeostasis. Natural polysaccharides,widely existed in nature,are a kind of biological macromolecules with prebiotics effects,which can improve a degree of physiological status by selectively changing the gut microbiota structure and function,enhancing the content of short chain fatty acids(SCFAs)and decreasing the level of inflammatory cytokines. In addition,the majority of polysaccharides can be degraded by gut microbiota to enhance their bioavailability and to promote the health state of the host. In this paper we discuss the interaction among polysaccharides and gut microbiotanatural,degradation mechanism and review gut microbiota as a target in the treatment of metabolic diseases,so as to provide future prospects of natural polysaccharides as " prebiotics " functional factors in the field of biological medicine and health products.
RESUMO
<p><b>OBJECTIVE</b>To study the application of three-dimensional reconstruction technique based on CT-MRI fusion in skull base surgery.</p><p><b>METHODS</b>To acquire the thin layer CT scan and MRI scanned images, to achieve image registration, fusion, segmentation and 3D visualization by using self-preparation software, to operate, observe and measure models by using methods of endoscopic observation, volume rendering segmentation, automatically and manually measure.</p><p><b>RESULTS</b>The center of the eye and foramen magnum in CT-MRI were used as point registration. Good coincidence of important anatomic landmarks were formed in the image fusion. The boundary of spotted graphical was clear and complete. The models showed a complete, continuous, smooth surface. Virtual endoscopy could display the inside three-dimensional structures of skull from nasal with fluent operations of rotation and transparency. The boundary of skull stump segmented after volume rendering segmentation was clear and smooth, and it could show bone signs and soft tissue models together. Cooperation of automatic measurement method [(32.007 ± 15.311) mm] and the manual measurement method [(30.240 ± 15.169) mm] for measuring the maximum diameters of the tumor model, the difference was significant (t = 8.409, P < 0.05).</p><p><b>CONCLUSIONS</b>The method of selecting the center of the eye and foramen magnum in point matching is scientific, simple and easy to operate. The models reconstructed based on CT-MRI fusion images can accurately reflect the size of the soft tissue and be better measured through the automatic measurement. Reconstruction models can be observed through the way of virtual endoscopic within the nasal cavity or volume rendering segmentation from outside to inside to frustrate the relationship of skull structures. Three-dimensional reconstruction techniques based on CT-MRI fusion in skull base surgery can be used to plan surgical approach, to assess the risk of surgery and to achieve space measurements, and it laid the foundation for the three-dimensional navigation.</p>