First-pass intrarenal hemodynamics were studied with superparamagnetic iron oxide particles and a T2-weighted TurboFLASH (fast low-angle shot) magnetic resonance (MR) imaging sequence. Four groups of five rabbits each were imaged after bolus injection of 40, 100, 140, and 200 mumol/kg iron, respectively. Images were acquired every 1.2 seconds, with an acquisition time of 700 msec. The signal intensity was measured in the cortex, outer medulla, inner medulla, and globally. In preliminary pathologic applications, two rabbits were imaged after ligation of the lumbar ureter and two after embolization of the renal artery. The reproducibility of the normal dynamics was evaluated with a cross-correlation test. On the images, the intravascular progression of the iron particles could be visualized within the cortex and the two compartments of the medulla in all cases. The maximal reduction in signal intensity in the cortex and medulla increased with the dose. The relationship between signal intensity decrease and dose was not linear, and the reproducibility of the signal intensity versus time plots was acceptable only at the 140 and 200 mumol/kg doses. The decrease in signal intensity was reduced and delayed in the embolized and hydronephrotic kidneys.
Root colonization by arbuscular mycorrhizal (AM) fungi of Artemisia umbelliformis, investigated in natural and cultivated sites in the Southern Alps of France, showed typical structures (arbuscules, vesicles, hyphae) as well as spores and mycelia in its rhizosphere. Several native AM fungi belonging to different Glomeromycota genera were identified as colonizers of A. umbelliformis roots, including Glomus tenue, Glomus intraradices, G. claroideum/etunicatum and a new Acaulospora species. The use of the highly mycorrhizal species Trifolium pratense as a companion plant impacted positively on mycorrhizal colonization of A. umbelliformis under greenhouse conditions. The symbiotic performance of an alpine microbial community including native AM fungi used as inoculum on A. umbelliformis was evaluated in greenhouse conditions by comparison with mycorrhizal responses of two other alpine Artemisia species, Artemisia glacialis and Artemisia genipi Weber. Contrary to A. genipi Weber, both A. umbelliformis and A. glacialis showed a significant increase of P concentration in shoots. Volatile components were analyzed by GC-MS in shoots of A. umbelliformis 6 months after inoculation. The alpine microbial inoculum increased significantly the percentage of E-β-ocimene and reduced those of E-2-decenal and (E,E)-2-4-decadienal indicating an influence of alpine microbial inoculum on essential oil production. This work provides practical indications for the use of native AM fungi for A. umbelliformis field culture.
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