Reproduction de l'Omble de fontaine,Salvelinus fontinalis (Mitchill), dans des lacs de différents pH

Mn, Fe, Cu, and Cd concentrations are reported for Lake Vanda, a closed-basin, meromictic, Antarctic lake and for its single major inflow, the Onyx River. Trace metal distributions in the upper lake and annual metal fluxes from the Onyx River were used to estimate chemical residence times in the mixed zone above the chemocline. Residence times, based on total metal loads, were 9.4 years for Mn; 1.4 years for iron; 174 years for copper; and 82 years for cadmium. Controls on the steady state concentrations of metals in this system are likely to include: particle settling of Fe and Mn; scavenging of minor elements on metal oxide surfaces; sulfide precipitation from the anoxic brine; and possibly uptake of metals on the surface of benthic algal mats. Model calculations show that metal removal by sinking phytoplankton can account for only a small fraction of the annual loss.     

髓周动静脉瘘（PMAVF）一例及文献复习

目的:探讨髓周动静脉瘘(perimedullary arteriovenous fistulas,PMAVF)的临床、影像学特征以及治疗方案的选择,以提高对该病的诊断水平。方法:报道1例PMAVF患者的临床诊治经过,并结合相关文献对PMAVF的临床、影像学特征和治疗方法进行总结。结果:1例表现为进行性下肢麻木伴无力的患者,并逐渐出现大小便失禁,胸腰段MRI示第9胸椎水平附近椎管内髓周血管明显迂曲扩张。行脊髓血管造影检查示右侧胸9肋间动脉发出的脊髓前动脉在胸12椎体水平通过分支供应的异常引流静脉走形于脊柱右侧。予Onyx胶栓塞引流静脉及瘘口,术后一年肌力恢复至4级左右。结论:PMAVF早期临床表现多不具有特异性,后逐渐出现进展性脊髓病变表现。脊髓MRI对提示PMAVF诊断具有重要作用,脊髓血管CTA和ceMRA有助术前判断供血动脉和瘘口位置。脊髓血管造影仍是诊断该病的金标准。手术切除和血管内治疗是治疗该病的主要方法。