Quantitative imaging of zinc, copper and lead in three distinct regions of the human brain by laser ablation inductively coupled plasma mass spectrometry.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to determine the distribution of the trace elements zinc, copper and lead in insular, central and hippocampal areas of thin tissue sections (thickness 20microm) through an entire human brain hemisphere. For the investigation of the tissue samples, a commercial laser ablation system was coupled to a double-focusing sector field ICP-MS. The regions of interest of healthy brain tissue (thickness 20microm) were scanned (raster area approximately 200mm(2)) with a focused laser beam (wavelength 266nm, diameter of laser crater 200microm and laser power density 3x10(9)Wcm(-2)). The ion intensities of (64)Zn(+), (63)Cu(+) and (208)Pb(+) were measured by LA-ICP-MS within the ablated area. For quantification purposes, matrix-matched laboratory standards were prepared by means of dosing of each analyte to the pieces of brain tissue. The mass spectrometric analysis yielded inhomogeneous and largely reciprocal distributions of Zn and Cu in the selected areas of investigated brain samples. The highest concentrations of Zn and Cu with the most distinct distribution pattern were found in the hippocampus (up to 15microg g(-1)). In contrast to zinc and copper, for lead, a more homogeneous distribution throughout all regions examined was found at a low concentration (in the ngg(-1) range) level within the analytical range of LA-ICP-MS.

Calcium and ROS-mediated activation of transcription factors and TNF-alpha cytokine gene expression in macrophages exposed to ultrafine particles.

Ultrafine (Uf) particles are a component of particulate air pollution suggested to be responsible for the health effects associated with elevations of this pollutant. We have previously suggested that Uf particles, through the induction of oxidative stress, may induce inflammation in the lung, thus exacerbating preexisting illness in susceptible individuals. Alveolar macrophages are considered to play a key role in particlemediated inflammation and lung disease. The effect of Uf particles on rat alveolar macrophages and human blood monocytes was investigated with reference to the roles of calcium and reactive oxygen species (ROS). TNF-alpha protein release, intracellular calcium concentration, TNF-alpha mRNA expression, and transcription factor activation were studied as end points after treatment of rat alveolar macrophages or peripheral blood monocytes. The calcium channel blocker verapamil, the intracellular calcium chelator BAPTA-AM, the calmodulin inhibitor W-7, and the antioxidants Trolox and Nacystelin (NAL) were included in combination with Uf particles. Verapamil reduced intracellular calcium concentration in rat alveolar macrophages on stimulation with Uf particles. This effect was also apparent with transcription factor AP-1 activation. All antagonists and antioxidants reduced Uf-stimulated nuclear localization of the p50 and p65 subunits of NF-kappaB in human monocytes. Verapamil, BAPTA-AM, and NAL reduced Uf-stimulated TNF-alpha protein release, whereas only verapamil reduced Uf-stimulated mRNA expression in rat alveolar macrophages. In human monocytes, verapamil, Trolox, BAPTA-AM, and W-7 reduced Uf-stimulated TNF-alpha protein release. These findings suggest that Uf particles may exert proinflammatory effects by modulating intracellular calcium concentrations, activation of transcription factors, and cytokine production through a ROS-mediated mechanism.