Impact of gadolinium-based contrast agents on the growth of fish cells lines

The present study was the first approach conducted under environmental concentrations of Gd-DOTA and Gd-DTPA-BMA to assess cellular impacts of these compounds. Gd-DOTA (Gadoteric acid) is one of the most stable contrast agent, currently used as Dotarem^® formulation during Magnetic Resonance Imaging exams. The study was mainly performed on a Zebra Fish cell line (ZF4; ATCC CRL-2050). At the concentrations of 0.127 nM and 63.59 nM (respectively 20 ng and 10 μg of Gd/L), we did not observed any toxicity of Dotarem^® but a slowdown of the cell growth was clearly measured. The effect is independent of medium renewing during 6 days of cell culturing. The same effect was observed i-with Gd-DOTA on another fish cell line (RT W1 gills; ATCC CRL-2523) and ii-with another contrast agent (Gd-DTPA-BMA - Omniscan^®) on ZF4 cells. On the ZF4 cell line, the diminution of the cell growth was of the same order during 20 days of exposure to a culture medium spiked with 63.59 nM of Dotarem^® and was reversible within the following 8 days when Dotarem^® was removed from the medium. As shown by using modified DOTA structure (Zn-DOTA), the effect may be due to the chelating structure of the contrast agent rather than to the Gd ion. Until now, the main attention concerning the impact of Gd-CA on living cells concerned the hazard due to Gd release. According to our results, quantifying the presence of Gd-CA chelating structures in aquatic environments must be also monitored.

Characterization of Gd loaded chitosan-TPP nanohydrogels by a multi-technique approach combining dynamic light scattering (DLS), asymetrical flow-field-flow-fractionation (AF4) and atomic force microscopy (AFM) and design of positive contrast agents for molecular resonance imaging (MRI)

Chitosan CS-tripolyphosphate TPP/hyaluronic acid HA nanohydrogels loaded with gadolinium chelates (GdDOTA ⊂ CS-TPP/HA NGs) synthesized by ionic gelation were designed for lymph node (LN) MRI. In order to be efficiently drained to LNs, nanogels (NGs) needed to exhibit a diameter ϕ < 100 nm. For that, formulation parameters were tuned, using (i) CS of two different molecular weights (51 and 37 kDa) and (ii) variable CS/TPP ratio (2 < CS/TPP < 8). Characterization of NG size distribution by dynamic light scattering (DLS) and asymetrical flow-field-flow-fractionation (AF4) showed discrepancies since DLS diameters were consistently above 200 nm while AF4 showed individual nano-objects with ϕ < 100 nm. Such a difference could be correlated to the presence of aggregates inherent to ionic gelation. This point was clarified by atomic force microscopy (AFM) in liquid mode which highlighted the main presence of individual nano-objects in nanosuspensions. Thus, combination of DLS, AF4 and AFM provided a more precise characterization of GdDOTA ⊂ CS-TPP/HA nanohydrogels which, in turn, allowed to select formulations leading to NGs of suitable mean sizes showing good MRI efficiency and negligible toxicity.

A new magnetic resonance imaging contrast agent loaded into poly(lacide-co-glycolide) nanoparticles for long-term detection of tumors

The incorporation of a lipophilic Gd chelate (GdDO3A-C12) in biocompatible PLGA poly(D, L-lactide-co-glycolide) nanoparticles was explored as an approach to increase the relaxivity of contrast agents for magnetic resonance imaging. By nanoprecipitation, it was possible to obtain PEGylated gadolinium nanoparticles (mean diameter of 155 nm) with high Gd loading (1.1 × 10(4) Gd centers per nanoparticle). The corresponding GdDO3AC12 ⊂ NPs nanoparticles exhibited an enhanced relaxivity (up to sixfold greater than DOTAREM® at 40 MHz) because the nanoparticle framework constrained the lipophilic Gd chelate motion and favorably impacted the Gd chelate rotational correlation time. T1-weighted imaging at 3 T on phantoms showed enhanced contrast for the GdDO3AC12 ⊂ NPs. Importantly, Gd chelate leakage was almost nonexistent, which suggested that these GdDO3AC12 ⊂ NPs could be useful for long-term MRI detection.

Encapsulation of contrast imaging agents by polypropyleneimine-based dendrimers

Polypropyleneimines (PPIs) functionalized by glycerol-based entities are prepared and characterized by diffusion-ordered spectroscopy NMR. Showing low cytotoxicity against MRC5 fibroblasts, their encapsulation capacities of gadolinium complexes was evaluated. T(1) measurements were performed to determine the relaxivity of the encapsulated gadopentetate dimeglumine (GdBOPTA) in dendrimers of fourth and fifth generation (GD-PPI-4 and GD-PPI-5). Comparison of the GdBOPTA relaxivity and the relaxivity of GdBOPTA-loaded dendrimers showed a slight increase of the gadolinium chelate relaxivity.

Vectorization of copper complexes via biocompatible and biodegradable PLGA nanoparticles

A double emulsion-solvent diffusion approach with fully biocompatible materials was used to encapsulate copper complexes within biodegradable nanoparticles, for which the release kinetics profiles have highlighted their potential use for a prolonged circulating administration.

[Survey in 2000: 3 cases]

BACKGROUND

We report three new cases of patients presenting scurvy. In the year 2000 this rare disease still occurs in France.

CASE REPORTS

The three patients, 2 men and a woman respectively 51, 50, and 73 years-old were alcoholics, and lived alone in difficult social conditions. Dietary survey indicated in the 3 cases inadequate vitamin C intake, and a regimen including solely bread, rice, pasta, and packet soup devoid of fresh vegetables and fruit. The cutaneous findings attributed to scurvy were: in the first patient, a woody inflammatory and painful oedema of the left leg associated with perifollicular petechial haemorrhages over the lower limbs, and hyperpigmentation of the facial skin with slate-gray spotty pigmentation of the tongue (pseudo-addisonian hyperpigmentation); in the second patient, an accentuation of a pre-existing acne becoming more inflammatory and extensive; and in the third patient, a diffuse petechial eruption on the abdomen and lower extremities. The diagnosis of scurvy was confirmed by low plasma ascorbic acid levels (< 6 mumol/l). All patients were treated with 1 to 2 g of oral ascorbic acid daily for 2 weeks resulting in rapid and dramatic response.

DISCUSSION

Scurvy is a rare disease in industrialized nations. Its incidence is unknown because of absence of total census. Dietary vitamin C deficiency represents the main risk factor exposing for scurvy among adults, often alcoholics and living in social isolation. Cutaneous features supporting the diagnosis of scurvy are described in our observations. The recognition of these cutaneous abnormalities is important because their association can be misleading, and erroneously interpreted as a sign of systemic vasculitis, or connective tissue disease. The diagnosis of scurvy is confirmed by the measurement of plasma ascorbic acid levels. Treatment is simple and based on the administration of vitamin C, which results in dramatic improvement.