Data processing of 3D and 4D in-vivo electron paramagnetic resonance imaging co-registered with ultrasound. 3D printing as a registration tool

We present the concept of image registration using ultrasound (US) and electron paramagnetic resonance (EPR) imaging and discuss the benefits of this solution, as well as its limitations. Both phantoms and murine tumors were used to test US and EPR image co-registration. Comparison of dental molding cast immobilization and predesigned cradle revealed that the latter approach is more effective in stabilizing the fiducial position. In vivo imaging of mouse tumors, image registration and comparison of fiducials system for 3D spatial as well as 4D spatial-spectral EPR imaging supported by 3D US were demonstrated. Ultrasound may provide a convenient alternative to other anatomical imaging methods for image registration in preclinical research. Of particular interest is a fusion of US tissue structure, doppler vascular function and EPR oxygen or redox imaging.

Angiomorphology of the pigmented Bomirski melanoma growing in hamster eye

An melanotic line of Bomirski Hamster Melanoma (BHM Ma) was implanted into the anterior chamber of the hamster eye and the ensuring vascular system was studied using scanning electron microscopy (SEM) of vascular corrosion casts. The tumor vasculature, induced mainly from the host iris vessels, showed generally disorganized and irregular patterns. Tortuous tumor capillaries of uneven contour with local dilatations and constrictions were drained by markedly dilated, thin-walled, venous vessels connected with the eye veins. Vascular sprouting and, less frequently, intussusceptive formation of new vessels were observed at the periphery and also within the tumor mass. The presence of numerous nodular outgrowths, varying in size, on the surface of dilated venules and venous vessels represent morphological evidence for continuous remodeling of the tumor vasculature. The observed features of the vascular system seem to provide a pathway for further tumor expansion. Our study showed that BHM Ma line, originating from an aggressive skin melanotic melanoma, implanted to the eye anterior chamber gave rise to rapidly growing tumors with the capability of inducing abundant vasculature which allows metastasis to the lungs, kidneys and regional lymph-nodes.

Tetrahydrobiopterin scavenges superoxide in dopaminergic neurons

Increased oxidative stresses are implicated in the pathogenesis of Parkinson's disease, and dopaminergic neurons may be intrinsically susceptible to oxidative damage. However, the selective presence of tetrahydrobiopterin (BH(4)) makes dopaminergic neurons more resistant to oxidative stress caused by glutathione depletion. To further investigate the mechanisms of BH(4) protection, we examined the effects of BH(4) on superoxide levels in individual living mesencephalic neurons. Dopaminergic neurons have intrinsically lower levels of superoxide than nondopaminergic neurons. In addition, inhibiting BH(4) synthesis increased superoxide in dopaminergic neurons, while BH(4) supplementation decreased superoxide in nondopaminergic cells. BH(4) is also a cofactor in catecholamine and NO production. In order to exclude the possibility that the antioxidant effects of BH(4) are mediated by dopamine and NO, we used fibroblasts in which neither catecholamine nor NO production occurs. In fibroblasts, BH(4) decreased baseline reactive oxygen species, and attenuated reactive oxygen species increase by rotenone and antimycin A. Physiologic concentrations of BH(4) directly scavenged superoxide generated by potassium superoxide in vitro. We hypothesize that BH(4) protects dopaminergic neurons from ordinary oxidative stresses generated by dopamine and its metabolites and that environmental insults or genetic defects may disrupt this intrinsic capacity of dopaminergic neurons and contribute to their degeneration in Parkinson's disease.

Effect of methanol intoxication on free-radical induced protein oxidation

Oxygen free radicals are generated during methanol-induced liver injury, as was shown for ethanol. The effect of methanol intoxication (6 g kg(-1) body wt.) on protein modification in the liver of rats was investigated. Electron spin resonance determination indicated an increase in the free radical signal 6 and 12 h after intoxication. After 7 days of treatment, the contents of malondialdehyde and carbonyl groups in proteins were significantly increased. The level of amino groups and sulphydryl groups and the amount of tryptophan in proteins were decreased, whereas the amount of bi-tyrosine was increased significantly. Changes in protein structure resulted both from free radical action and formaldehyde generation during methanol intoxication.

Experimental ruthenium plaque therapy of amelanotic and melanotic melanomas in the hamster eye

The effects of beta-radiation on melanoma implanted into the hamster's eye were investigated. Two Bomirski hamster melanomas (BHMs), differing in their melanin content, were compared with regard to their radiosensitivity to ruthenium-106 (106Ru) radiation. Tumours growing in the iris were irradiated with 3, 6 or 10 Gy of 106Ru given as a single dose or in four fractions at 24 h Intervals. Tumour growth kinetics and distant metastases were studied, and the eyeballs were examined histologically. Dose-dependent delay of tumour growth was observed in both melanomas. After treatment with a dose of 6 Gy, the Ab amelanotic tumours grew 2.6 times slower, and the Ma melanotic tumours 1.4 times slower than untreated ones. The location of metastases differed in the two tested lines--pigmented metastases were found mainly in the lungs, while unpigmented metastases were found mainly in the kidneys. Histopathological analysis showed signs of blood vessel damage such as endothelial cells swelling, erythrocyte extravasation and tumour necrosis. This last finding increased with the rising dose of beta-radiation. Pigmented tumours were found to be two times more resistant to beta-radiation than amelanotic ones. The pattern of metastases of BHMs is determined by the type of melanoma (Ab or Ma). Exposure to beta-radiation from 106Ru did not significantly affect either the number or size of metastases except at a dose of 10 Gy. This dose caused a statistically significant decrease in the number of metastases in the Ma melanotic subline.