Body distribution of inhaled fluorescent magnetic nanoparticles in the mice.

Reducing the particle size of materials is an efficient and reliable tool for improving the bioavailability of a gene or drug delivery system. In fact, nanotechnology helps in overcoming the limitations of size and can change the outlook of the world regarding science. However, a potential harmful effect of nanomaterial on workers manufacturing nanoparticles is expected in the workplace and the lack of information regarding body distribution of inhaled nanoparticles may pose serious problem. In this study, we addressed this question by studying the body distribution of inhaled nanoparticles in mice using approximately 50-nm fluorescent magnetic nanoparticles (FMNPs) as a model of nanoparticles through nose-only exposure chamber system developed by our group. Scanning mobility particle sizer (SMPS) analysis revealed that the mice were exposed to FMNPs with a total particle number of 4.89 x 10(5) +/- 2.37 x 10(4)/cm(3) (low concentration) and 9.34 x 10(5) +/- 5.11 x 10(4)/cm(3) (high concentration) for 4 wk (4 h/d, 5 d/wk). The body distribution of FMNPs was examined by magnetic resonance imaging (MRI) and Confocal Laser Scanning Microscope (CLSM) analysis. FMNPs were distributed in various organs, including the liver, testis, spleen, lung and brain. T2-weighted spin-echo MR images showed that FMNPs could penetrate the blood-brain-barrier (BBB). Application of nanotechnologies should not produce adverse effects on human health and the environment. To predict and prevent the potential toxicity of nanomaterials, therefore, extensive studies should be performed under different routes of exposure with different sizes and shapes of nanomaterials.

In vivo 1H MR spectroscopic findings in traumatic contusion of ICR mouse brain induced by fluid percussion injury.

PURPOSE: The purpose of this study was to investigate the proton metabolic differences of the right parietal cortex with experimental brain contusions of ICR mouse induced by fluid percussion injury (FPI) compared to normal controls and to test the possibility that 1H magnetic resonance spectroscopy (MRS) findings could provide neuropathologic criteria in the diagnosis and monitoring of traumatic brain contusions. MATERIALS AND METHODS: A homogeneous group of 20 ICR male mice was used for MRI and in vivo 1H MRS. Using image-guided, water-suppressed in vivo 1H MRS with a 4.7 T MRI/MRS system, we evaluated the MRS measurement of the relative proton metabolite ratio between experimental brain contusion of ICR mouse and healthy control subjects. RESULTS: After trauma, NAA/Cr ratio, as a neuronal marker decreased significantly versus controls, indicating neuronal loss. The ratio of NAA/Cr in traumatic brain contusions was 0.90+/-0.11, while that in normal control subjects was 1.13+/-0.12 (P=0.001). The Cho/Cr ratio had a tendency to rise in experimental brain contusions (P=0.02). The Cho/Cr ratio was 0.91+/-0.17, while that of the normal control subjects was 0.76+/-0.15. However, no significant difference of Glx/Cr was established between the experimental traumatic brain injury models and the normal controls. DISCUSSION AND CONCLUSIONS: The present 1H MRS study shows significant proton metabolic changes of parietal cortex with experimental brain contusions of ICR mouse induced by FPI compared to normal controls. In vivo 1H MRS may be a useful modality for the clinical evaluation of traumatic contusions and could aid in better understanding the neuropathologic process of traumatic contusions induced by FPI.