Different extraction methods bring about distinct physicochemical properties and antioxidant activities of Sargassum fusiforme fucoidans.

Fucoidan is a complex sulfated polysaccharide and an active component found in the cell wall of brown seaweeds. In the present study, fucoidans were obtained from Sargassum fusiforme using different extraction methods, including hot water (prepared fucoidan was named as WSFF), dilute hydrochloric acid (ASFF), and calcium chloride solution (CSFF). The assessments were performed on S. fusiforme fucoidans based on their chemical composition, molecular conformations, and in vitro antioxidant activities. ASFF showed the maximum extraction yield (11.24%), whereas CSFF exhibited the minimum yield (3.94%). The monosaccharide composition of WSFF, ASFF, and CSFF was similar, but the molar ratio of monosaccharide was quite different. Moreover, their molecular weight, Fourier transform infrared (FT-IR) spectrum, surface morphology, uronic acid content and degree of sulfation were distinct. The Congo red test and Circular dichroism spectroscopy analysis displayed some differences in solution conformation of these samples. Furthermore, WSFF, ASFF, and CSFF showed distinct in vitro antioxidant activities evaluated by DPPH and hydroxyl radical scavenging assays. The present study provides scientific evidence on the influences of extraction methods on the physicochemical characteristics, conformation behaviors and antioxidant activities of S. fusiforme fucoidans.

Analysis of the stress distribution of the subtalar joint and fusion efficacy after double-screw insertion.

BACKGROUND: Screw fixation is a typical technique for the isolated subtalar joint. However, no consensus has been reached on how to select the most suitable insertion position and direction. This study aims to find the ideal screw insertion and then explore its influence on the clinical efficacy of subtalar fusion by analyzing the effects of different cannulated screw insertions on the stress distribution, anti-rotary strength, and anti-inversion/eversion strength of the subtalar joint. METHODS: In this study, we investigated three cannulated screw insertions for subtalar fusion: screw insertion with the most uniform stress distribution (group A), lateral-medial parallel screw insertion (group B), and traditional longitudinally parallel screw insertion (group C). The effects of these three insertions on the loading stress of the subtalar joint (including stress distribution, anti-inversion/eversion strength, and anti-rotary strength) were comparatively analyzed with the three-dimensional finite element method to screen the ideal screw insertion. Moreover, a prospective study was conducted to analyze the influence of the ideal screw insertion on subtalar fusion, including the fusion rate, fusion time, and clinical efficacy (VAS score, AOFAS score, and complications). RESULTS: Group B was worse than group A with respect to the stress distribution uniformity, but slightly better than group C, and better than both groups A and C in terms of the anti-rotary strength and anti-inversion/eversion strength. The screw insertion based on the most uniform stress distribution is not feasible in surgery. Therefore, the lateral-medial antiparallel screw insertion is the ideal insertion. From January 2012 to June 2016, 48 cases were treated by subtalar fusion with the ideal screw insertion, and then followed up for 30.6 months (12-48 months). The fusion was proved in all 48 cases with a fusion rate of 100% by X-ray or CT scan. The mean time of fusion was 12.8 weeks (12-16 weeks). The VAS score decreased from 6.00 before operation to 1.03 on the last visit (P < 0.05), and the AOFAS score increased from 57.0 to 85.6 (P < 0.05), with a good and excellent rate of 95.8%. CONCLUSIONS: The lateral-medial parallel screw insertion not only demonstrates a good stress distribution profile of the subtalar joint but also has advantages such as easy localization and operation during surgery, as well as a high fusion rate and few complications after surgery. Therefore, it is a safe, accurate, and effective fixation mode that is worthy of being popularized clinically.