Nitroxide derivatives for imaging of hypercholesterolemia-induced kidney dysfunction and assessing the effectiveness of antilipidemic drugs.

The present study was designed to clarify the possibility for application of nitroxide derivatives in magnetic resonance imaging (MRI) of hypercholesterolemia-mediated renal dysfunction in mice, as well as to assess the effectiveness of antilipidemic drugs (cholestyramine and ezetimibe). The mice were separated in four groups: (i) on a normal diet (ND) without medication (control); (ii) on a high cholesterol diet (CD) without medication; (iii) CD mice receiving cholestyramine; and (iv) CD mice receiving ezetimibe. In CD mice without medication, a hypercholesterolemia was developed, detected by the increasing of total plasma cholesterol and non-HDL cholesterol, and decreasing of HDL cholesterol. The hypercholesterolemia compromised renal function: blood urea nitrogen, creatine and uric acid increased significantly, accompanied with development of glomerulosclerosis, enhancement of the amount of neutrophils and overexpression of metalloproteinase-9. The mice were subjected to anesthesia and MR imaging was performed on 7 T magnet (T1-weighted incoherent gradient-echo sequence; fast low-angle shot). The region-of-interest was selected within the kidney. The images were obtained before and after injection of contrast probe [carbamoyl-PROXYL (CMP) or Gd-DTPA]. In the kidney of ND mice, the MRI signal intensity increased after injection of CMP, reached a maximum (very well-defined renal filtration peak) and decreased to the baseline level within 14 min. In kidney of CD mice, the CMP-mediated enhancement of MRI signal was not detected. Antilipidemic drugs patially abolished the effect of hypercholesterolemia on CMP-enhanced MRI in the kidney. The kinetic curves of Gd-enhanced MRI signal had also different profiles in the kidney of ND and CD mice. They were similar to the profiles of the kinetic curves, obtained from MR urography of healthy human and human with renal pathology, respectively. The present study suggests that CMP is a suitable MRI contrast probe for visualization of hypercholesterolemia-induced renal dysfunction in intact animals and the assessment of the efficacy of antilipidemic drugs. The probe was applied at a concentration that was 3 times lower than the LD50 for intravenous administration in mice. Since the probe is excreted by the kidney, it could be considered harmless for mammalians in the selected dose and appropriate candidate for translational research.

Gadolinium labelled nanoliposomes as the platform for MRI theranostics: in vitro safety study in liver cells and macrophages.

Gadolinium (Gd)-based contrast agents are extensively used for magnetic resonance imaging (MRI). Liposomes are potential nanocarrier-based biocompatible platforms for development of new generations of MRI diagnostics. Liposomes with Gd-complexes (Gd-lip) co-encapsulated with thrombolytic agents can serve both for imaging and treatment of various pathological states including stroke. In this study, we evaluated nanosafety of Gd-lip containing PE-DTPA chelating Gd+3 prepared by lipid film hydration method. We detected no cytotoxicity of Gd-lip in human liver cells including cancer HepG2, progenitor (non-differentiated) HepaRG, and differentiated HepaRG cells. Furthermore, no potential side effects of Gd-lip were found using a complex system including general biomarkers of toxicity, such as induction of early response genes, oxidative, heat shock and endoplasmic reticulum stress, DNA damage responses, induction of xenobiotic metabolizing enzymes, and changes in sphingolipid metabolism in differentiated HepaRG. Moreover, Gd-lip did not show pro-inflammatory effects, as assessed in an assay based on activation of inflammasome NLRP3 in a model of human macrophages, and release of eicosanoids from HepaRG cells. In conclusion, this in vitro study indicates potential in vivo safety of Gd-lip with respect to hepatotoxicity and immunopathology caused by inflammation.

[Evaluation of the elimination and safety of gadodiamide injection in patients with hemodialysis].

We performed this study to evaluate the safety and elimination of gadodiamide injection in patients with hemodialysis (HD). The subjects were 10 patients on maintenance HD therapy, after receiving gadodiamide injection for magnetic resonance imaging (MRI) examination. The patients' mean age was 59.4 +/- 3.5 years, and their mean hemodialysis period was 70.6 +/- 20.4 months. Diseases for MRI examination were liver tumor (n=2), gallbladder tumor (n=1), renal tumor (n=3), pancreas tumor (n=1), abdominal aortic aneurysm (n=1), and arteriosclerosis obliterans (n=2). HD was performed routinely three times a week for 4 hours. Cellulose triacetate (CTA) membranes were used for 5 patients, polysulphone (PS) for 3 patients and polyester-polymer alloy (PEPA) for 2 patients. Serum levels of gadodiamide were analyzed before and after the first and second HD, and before the third and fourth HD. At the first HD, the concentration of gadodiamide in dialysate was analyzed every hour. Gadodiamide was eventually eliminated over time; 74.1% of the gadodiamide was dialyzed after the first HD and 98.8% after the third HD. There were no significant changes in the removal rate and laboratory parameters between each membrane. The present study suggests that gadodiamide could be removed by HD therapy efficiently thereby indicating that gadodiamide injection is possible in patients with HD.

Antitumoral activity and toxicity of PEG-coated and PEG-folate-coated pH-sensitive liposomes containing ¹59Gd-DTPA-BMA in Ehrlich tumor bearing mice.

In the present study, PEG-coated pH-sensitive and PEG-folate-coated pH-sensitive liposomes containing the ¹59Gd-DTPA-BMA were prepared and radiolabeled through neutron activation technique, aiming to study the in vivo antitumoral activity and toxicity on mice bearing a previously-developed solid Ehrlich tumor. The treatment efficacy was verified through tumoral volume increase and histomorphometry studies. The toxicity of formulations was investigated through animal weight variations, as well as hematological and biochemical tests. The results showed that after 31 days of treatment, animals treated with radioactive formulations had a lower increase in tumor volume and a significantly higher percentage of necrosis compared with controls revealed by histomorphometry studies. Furthermore, mice treated with radioactive formulations exhibited lower weight gain without significant hematological or biochemical changes, except for toxicity to hepatocytes which requires more detailed studies. From the results obtained to date, we believe that the radioactive formulations can be considered potential therapeutic agents for cancer.

Comparative efficacy of and sequence choice for two oral contrast agents used during MR imaging.

OBJECTIVE: Our objective was to compare the efficacy of a positive and a negative oral contrast agent and to determine the optimal sequence choice for use in pelvic MR imaging. SUBJECTS AND METHODS: We undertook a prospective randomized trial of 57 patients with pelvic cancer who were examined with MR imaging after oral administration of a positive contrast agent (27 patients) or a negative contrast agent (30 patients). T1- and T2-weighted breath-hold and non-breath-hold gradient-recalled echo and turbo spin-echo sequences were obtained. Using the hard-copy images, we graded filling and distention of the small bowel, bowel wall conspicuity, delineation of normal and pathologic structures, and artifacts. RESULTS: Good or excellent small-bowel filling and distention was obtained in 17 patients (63%) receiving the positive agent and in 26 patients (87%) receiving the negative agent, and bowel wall conspicuity was graded good or excellent in 19 patients (70%) and 20 patients (67%), respectively. Normal and pathologic structures were better delineated with the negative agent (20 patients [74%] and 27 patients [90%], respectively; p = .02). Breath-hold gradient-recalled echo T1-weighted images were preferred for the positive agent (78%), and breath-hold T2-weighted images were preferred for the negative agent (93%). Contrast artifacts were more frequently seen with the negative agent (11% and 93%, respectively; p = .0001), and such artifacts were eliminated using T2-weighted sequences. CONCLUSION: Both contrast agents were effective in pelvic MR imaging, but delineation of normal and pathologic structures was better with the negative agent. Gradient-recalled echo T1-weighted sequences are recommended for positive contrast agents, and breath-hold T2-weighted sequences are recommended for negative contrast agents.