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Authors: Zsófia Koltai, Bernadett Szabó, Judit Jakus and Péter Vajdovich

Messenger RNA levels of oncogenic tyrosine kinases were determined in canine mammary tumours using real-time RT-PCR. The following tyrosine kinases and vascular endothelial growth factors (VEGF) were examined in malignant and healthy mammary tissues of 13 dogs: VEGFR1, VEGFR2, EGFR, ErbB2, PDGFR1, c-KIT and c-MET. Expression levels of all these factors were significantly higher in tumour samples than in normal mammary tissues taken from the same animal. Higher grading was associated with higher VEGFR1 levels. Grade III tumours showed significantly higher VEGF, c-MET and c-KIT mRNA expression, while Grade I tumours with lower malignancy showed significantly higher PDGFR1 and EGFR expression than tumours classified as Grade II or III. The increased presence of VEGF, VEGFR1, c-KIT and c-MET is a negative prognostic factor as these signal transduction molecules contribute to increased tumour malignancy. The presented data provide evidence, for the first time, for the existence of a complex overexpression and dysregulation of VEGF and several oncogenic tyrosine kinases such as VEGR1, PDGFR1, c-KIT and c-MET in canine mammary tumours. Therefore, canine mammary tumours may be potential targets for tyrosine kinase inhibitor therapy.

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Authors: András Németh, Krisztián Stadler, Judit Jakus and Tamás Vidóczy


Pitfalls of peroxynitrite (ONOO) formation in diabetic rat aorta on luminol-induced chemiluminescence (LCL) are investigated based on a detailed reaction mechanism in a case where 1.0 × 10−7 M s−1 superoxide formation rate and nitric oxide (NO) formation were measured by electron paramagnetic resonance, while ONOO formation by LCL. Modeling ONOO formation at equimolar reactant ratio at pH 7.4 and 37 °C predicts 2.0 nM ONOO and 2.1 × 10−6 M steady-state NO concentrations, which are both biologically relevant. Comparison of steady-state concentrations to those obtained by modeling the LCL intensity at pH 10 shows that ONOO concentration increases with 10% while peroxynitrous acid (ONOOH) concentration decreases complying with the pH shift. Evaluation of steady-state reaction rates reveals that the contribution of CO3 •− radicals to the formation of luminol radicals is 76%, that of NO2 is 24%, considerable, but that of OH radicals negligible. The contribution of additional superoxide formation by autoxidation of luminol is 13%, not negligible, but that of ONOOH homolysis is negligible. The NO2 is predominantly formed from the decomposition of the ONOO–carbon dioxide adduct and only 0.5% directly from NO oxidized by molecular oxygen. But the contribution of the latter pathway depends strongly on the NO and superoxide formation rate ratio, at a ratio of 2:1, it would increase to 14%. The measured time interval of the initial increase of LCL intensity complies with the time needed luminol aorta outside and inside concentrations in the sample to be equalized by diffusion, the 7 × 10−3 s−1 rate constant obtained by modeling enabled to estimate 5 × 10−7 cm2 s−1 as the diffusion coefficient of luminol in the diabetic rat aorta.

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