Figure 4.

Mild systemic heating improves tumour oxygenation. (A) Hypoxic areas in tumour sections were identified using immunohistochemistry (IHC) to label pimonidazole hydrochloride (Hypoxyprobe-1) adducts of proteins and peptides that are formed at low oxygen tension. Panels on the left are micrographs (10×) from tumour sections from a control unheated mouse and from heated mice 2 h and 24 h post-heating. Panels on the right are binary images of the micrographs on the left; the binary threshold was done using NIH ImageJ. The micrographs show extensive hypoxic areas in the control tumour and in the tumour 2 h post-heating. The hypoxic area is much reduced at 24 h post-heating. (B) A plot of the number of IHC stained sections from unheated control mice and those from mice at 2 h and 24 h post-heating. The pixel counts were obtained using NIH ImageJ. There was no significant decrease in the number of hypoxic pixels at 2 h post-heating but at 24 h post-heating there was significant decrease in hypoxia in the tumours. Scale bar = 100 μm (n = 3 per group, ANOVA *p <0.05; **p <0.01).