The release of Gd from all linear Gd3+ complexes in human serum was several orders of magnitude greater than predicted by the conditional stability constants. After 15 days, release of Gd3+ from the nonionic linear GBCAs was about 10 times higher than from the ionic linear GBCAs. Elevated serum phosphate levels accelerated the release of Gd3+ from nonionic linear GBCAs and, to a lesser degree, from the ionic linear GBCAs. All 3 macrocyclic GBCAs remained stable in human serum at both normal and elevated phosphate levels.

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Amorphous silicon films (a-Si:H) with a hydrogen content of 10 at. % were crystallized employing a step-by-step crystallization method. Structural changes during the sequential crystallization process were monitored by Raman spectrometry. Initially, at low laser fluences EL, a two-layer system is created. Independent of the thickness of the a-Si:H layer explosive crystallization of a thin surface layer is observed at EL⩾100 mJ/cm2 confirming recent theoretical results. Crystallization is accompanied by dehydrogenation. In completely crystallized poly-Si a residual H concentration of up to 5 at. % was observed.

Purpose:To investigate the role of excess ligand present in gadolinium (Gd) -based contrast agents in the development of nephrogenic systemic fibrosis (NSF). Using a dosing regimen to simulate the exposure seen in patients with severe renal impairment, we investigated the effect of excess ligand on Gd-deposition and the depletion of endogenous ions. Materials and Methods:Gadodiamide and gadoversetamide were formulated with 0%, 5%, and 10% excess ligand. Forty-two, healthy, male Hannover Wistar rats received daily intravenous injections of each formulation over a period of 20 days. At the end of the study, histopathological analysis of the skin was performed and the concentrations of Gd, Zn, and Cu were measured in several tissues. The levels of Zn in the urine were also measured. Results:The most severe skin lesions were observed after injection of formulations containing 0% free ligand and in those animals with the highest Gd concentrations in the skin. There were no significant reductions in the levels of Zn or Cu observed in the skin; however, the levels of Zn in the urine were elevated following administration of formulations with the highest amount of excess ligand. Conclusion:Our findings suggest that there is an inverse correlation between the amount of excess ligand present in Gd-containing contrast agents and the amount of Gd in the tissue, and further underline the importance of the inherent stability of these agents in the development of NSF.

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Nephrogenic systemic fibrosis (NSF) is a potentially severe systemic disease typically characterized by fibrosis of the skin and connective tissues. The etiology of NSF is still unknown but is likely to be multifactorial. Specific triggers under scientific evaluation have included surgery and/or the occurrence of thrombosis or other vascular injury, proinflammatory state, the administration of high doses of erythropoietin, and more recently the use of gadolinium-based contrast agents (GBCAs). The aim of this review is to summarize knowledge regarding the pathogenesis of NSF and the potential role of GBCAs in its pathology, with a focus on animal experiments. The potential role of complex stability of GCBAs will be highlighted by results from several in vitro and in vivo experiments in rodent models of NSF.

The results of this preclinical study support the use of 5/6-nephrectomized rats as a model for prolonged circulation time of GBCAs as seen in patients with severe renal impairment. Surgically induced severe renal impairment resulted in delayed clearance of the administered GBCAs in the study animals. The highest amount of Gd was observed in the skin after treatment with the nonionic linear GBCAs, whereas the lowest Gd values were observed after treatment with the macrocyclic agent. This suggests that the difference in the Gd values observed in rat skin tissue after treatment with the different GBCAs is caused of a different propensity of the different GBCAs to release Gd in vivo. However, the analytical method used does not distinguish between chelated and unchelated Gd.