Selective ligninolysis of wheat straw and wood chips by the white-rot fungus Lentinula edodes and its influence on in vitro rumen degradability

Background： The present work investigated the influence of lignin content and composition in the fungal treatment of lignocellulosic biomass in order to improve rumen degradability. Wheat straw and wood chips,differing in lignin composition, were treated with Lentinula edodes for 0, 2, 4, 8 and 12 wk and the changes occurring during fungal degradation were analyzed using pyrolysis-gas chromatography-mass spectrometry and detergent fiber analysis.Results： L. edodes preferentially degraded lignin, with only limited cellulose degradation, in wheat straw and wood chips, leaving a substrate enriched in cellulose. Syringyl（S）-lignin units were preferentially degraded than guaiacyl（G）-lignin units, resulting in a decreased S/G ratio. A decreasing S/G ratio（wheat straw： r =-0.72, wood chips： r =-0.75） and selective lignin degradation（wheat straw： r =-0.69, wood chips： r =-0.88） were correlated with in vitro gas production（IVGP）, a good indicator for rumen degradability.Conclusions： L. edodes treatment increased the IVGP of wheat straw and wood chips. Effects on IVGP were similar for wheat straw and wood chips indicating that lignin content and 3D-structure of cell walls influence in vitro rumen degradability more than lignin composition.

克罗恩病初次手术与多次手术患者的治疗及结局:基于PRACTICROHN研究数据

背景:克罗恩病(CD)手术往往预后不佳,常需再次手术。本研究旨在比较初次手术与多次手术CD患者的术后治疗及临床结局。方法:本研究为观察性研究,纳入2007年1月至2010年12月间西班牙26家医院收治的行回结肠切除吻合术的成人CD患者。从医疗记录中回顾性收集数据。结果:314例患者纳入分析,其中262例(83%)为初次手术病例,52例(17%)既往有过CD手术史。除狭窄型病变的患者比例再手术组相对较高以外(P=0.03),其余基线资料两组患者的差异均无统计学意义。术后接受预防性药物治疗的患者比例再手术组高于初次手术组(P=0.04)。再手术患者临床复发的时间与是否接受预防性药物治疗无关;但对于初次手术患者,接受预防性药物治疗者无复发生存时间更长(P=0.03)。结论:与初次手术者相比,既往有过CD手术史的患者术后更多接受了预防性药物(免疫调节剂)治疗。尽管预防性药物治疗可以预防初次手术者的临床复发,但并没有降低再次手术患者的复发风险。提示术后预防性药物治疗仍应仅限于初次手术患者。