三种输尿管镜治疗输尿管上段结石的疗效比较

目的:比较半硬性输尿管镜、输尿管软镜、孙氏末段可弯输尿管镜治疗输尿管上段结石的临床疗效,为临床上治疗方式的选择提供参考。方法:回顾性分析2015年8月到2017年12月间于上海市第十人民医院泌尿外科因输尿管上段结石行输尿管镜下钬激光治疗的515例患者的临床资料。按照所用输尿管镜类型分为3组:硬镜组(给予半硬性输尿管镜治疗)297例,软镜组172例(给予输尿管软镜治疗),孙氏镜组(给予孙氏末段可弯输尿管镜治疗)46例。比较三组的手术时间、一期清石率、术后住院时间及术中、术后并发症。结果:硬镜组、软镜组、孙氏镜组清石率分别为81.5%、94.2%、95.7%,其中软镜组、孙氏镜组清石率显著高于硬镜组(P0.05)。硬镜组、软镜组、孙氏镜组术中并发症发生率分别为18.9%、5.8%、4.3%,其中硬镜组术中并发症发生率显著高于软镜组和孙氏镜组(P0.05),三组术后并发症发生率整体比较差异无统计学意义(P0.05)。硬镜组、软镜组、孙氏镜组平均手术时间分别为(28.6±6.2)min、(49.4±12.4)min、(26.1±6.5)min,软镜组平均手术时间显著高于硬镜组及孙氏镜组,差异有统计学意义(均P0.05)。硬镜组、软镜组、孙氏镜组平均住院时间分别为(5.4±3.2)d、(6.7±5.7)d、(5.0±2.5)d,软镜组住院时间显著高于硬镜组和孙氏镜组,差异有统计学意义(均P0.05)。结论:软镜清石效果和手术安全性较硬镜更有优势,但手术耗时长,患者术后住院时间长。孙氏镜有望成为治疗输尿管上段结石的更佳选择。     

Enhanced chitosan production and modeling hyphal growth of Mucor rouxii interpreting the dependence of chitosan yields on processing and cultivation time

Chitosan is a major structural component of fungal cell walls and has diverse medical and other applications. However, cost‐effective culture and extraction methods for fungi need to be developed. Therefore, Mucor rouxii was grown on YPG‐media in both submerged batch and semi‐continuous cultures. Chitosan was extracted from the mycelia to explore strategies to enhance yields and production rates. As observed in earlier studies, M. rouxii is able to adapt to shear stress when cultured semi‐continuously. Modeling the hyphal growth of batch experiments shows that the mycelia were ruptured by shear forces within a short cultivation time shown by a decreased hyphal length. However, an increasing chitosan content was observed with an increasing cultivation period in semi‐continuous cultures, which is an indication for the adaption to shear stress. Semi‐continuous culture resulted in the highest contents of extractable chitosan. The results and models of hyphal growth, including tip extension and branching, suggest that repeated batch cultures may be optimal for chitosan production.     

Variations in mountain vegetation use by reindeer (Rangifer tarandus) affects dry heath but not grass heath

Question: Are differences in landscape use of semi‐domesticated reindeer reflected in the vegetation of summer grazing grounds? Location: Alpine heaths, central east Sweden. Methods: Dry heath and grass heath vegetation plots with inferred grazing intensities (high, intermediate and low) were selected a priori from an interpolated pellet count map compiled in 2002. In each plot, faecal pellets were counted, environmental variables measured and vegetation sampled by listing presence and absence. Species composition was compared with a detrended correspondence analysis, and a canonical correspondence analysis was used to infer relations between species composition and environmental variables. Plots were also clustered to provide groupings for an indicator species analysis. Results: Significant differences in faecal pellet count were present between the highest and lowest grazing intensities for both vegetation types, showing that the pattern in the interpolated pellet maps was robust. Differences in species composition between grazing intensities were found for the dry heath only. Here, there was an apparent grazing gradient, with lichens and mosses in the low‐use plots and grasses and herbs in the high‐use plots. No such gradient was found for the grass heath. Conclusions: Within the dry heath vegetation type, grazing levels had a subtle effect on the vegetation, while no effects were seen in the grass heath, probably as a result of the dominance of more grazing‐tolerant graminoids. Even in the dry heath, species richness did not differ between grazing levels, but the relative abundances of species differed.     

Variation in species composition and vegetation structure of succulent scrub on Tenerife in relation to environmental variation

Abstract. On Tenerife, the occurrence of environmental gradients over short distances provides a unique opportunity to investigate the relationship between vegetation and environmental factors. In the semi‐arid coastal region of Tenerife, floristic composition, species richness and vegetation structure of perennial plants have been studied in 67 locations covering the existing precipitation gradient. On the island as a whole, variation in species composition could be best explained by mean annual precipitation; at coastal sites, substrate age and soil characteristics also played a significant role. On the other hand, substrate chemistry and the type of eruptive material explained little of the floristic variation. Stand biomass was strongly correlated with mean annual precipitation and was, on the youngest lava flows studied, also affected by substrate age. The native stem succulent species made up the bulk of total biomass along the whole precipitation gradient. Disturbed and undisturbed sites differed significantly in stand biomass and cover. Species richness was correlated with precipitation and substrate age. Distribution of plant functional types was also related to the precipitation gradient. The relative abundance of hemicryptophytes and shrubs with non‐hairy leaves increased with increasing precipitation whereas the ratio of shrubs with hairy/non‐hairy leaves and succulent plants decreased. Some alien plants were quite frequent at disturbed sites but, on the whole, they contributed little to the species spectrum and to the stand biomass. Undisturbed sites remained almost free of introduced species not considering annuals.     

A hierarchical model for analysing the stability of vegetation patterns created by grazing in temperate pastures

Questions: Does vegetation structure display any stability over the grazing season and in two successive years, and is there any correlation between the stability of these spatial patterns and local sward composition? Location: An upland grassland in the French Massif Central. Method: The mosaic of short and tall vegetation stands considered as grazed and ungrazed patches respectively is modeled as the realization of a Boolean process. This method does not require any arbitrarily set sward‐height thresholds to discriminate between grazed and ungrazed areas, or the use of additional variables such as defoliation indexes. The model was validated by comparing empirical and simulated sward‐height distributions and semi‐variograms. Results: The model discriminated between grazed and ungrazed patches at both a fine (1 m²) and a larger (500 m²) scale. Selective grazing on legumes and forbs and avoidance of reproductive grass could partly explain the stability of fine‐scale grazing patterns in lightly grazed plots. In these plots, the model revealed an inter‐annual stability of large‐scale grazing patterns at the time peak biomass occurred. At the end of the grazing season, lightly grazed plots showed fluctuating patch boundaries while heavily grazed plots showed a certain degree of patch stability. Conclusion: The model presented here reveals that selective grazing at the bite scale could lead to the creation of relatively stable patches within the pasture. Locally maintaining short cover heights would result in divergent within‐plot vegetation dynamics, and thus favor the functional diversity of vegetation.