Fluorescence ratio imaging of interstitial pH in solid tumours: effect of glucose on spatial and temporal gradients

Abstract

Summary Tumour pH plays a significant role in cancer treatment. However, because of the limitations of the current measurement techniques, spatially and temporally resolved pH data, obtained non-invasively in solid tumours, are not available. Fluorescence ratio imaging microscopy (FRIM) has been used previously for noninvasive, dynamic evaluation of pH in neoplastic tissue in vivo (Martin GR, Jain RK 1994, Cancer Res., 54, 5670 -5674

Effects of light fractionation and different fluence rates on photodynamic therapy with 5-aminolaevulinic acid in vivo

“…Therefore, these results do not support the hypothesis that lower PDT fluence rates are associated with increased efficiency of tumour response (Sitnik and Henderson, 1998). Surprisingly, in this study no complete remission of the radiation induced fibro sarcoma (RIF) tumour was obtained using Photofrin s (5 mg kg À1 ) and high-dose PDT (150 mW cm À2 , 100 J cm À2 ), whereas in our model using these parameters and Photofrin s in five out of six tumours a complete remission is achieved (Dellian et al, 1996).…”

“…In addition, measuring the tumour volume of the subcutaneously implanted amelanotic melanoma after PDT has been studied as well to evaluate the efficacy of different anticancer treatments (Weiss et al, 1990;Szeimies et al, 1995;Dellian et al, 1996;Abels et al, 1997a, b).…”

A model for acid-mediated tumour growth with nonlinear acid production term

“…We also remark that due to the pulse-like nature of the acid profile we have that the concentration of H + ions is primarily located in the region of the interstitial gap. This model prediction is in line with what has been observed experimentally (Dellian et al, 1996;Helmlinger et al, 1997;Martin and Jain, 1994).…”

“…The model's solution for the concentration of excess H + ions presents as a front Gatenby and Gawlinski, 1996), which suggests that the concentration of acid will be highest inside the tumour, with an almost homogeneous concentration, rather than at the tumour-host interface. Tumours tend to present with very heterogeneous acid profiles (Helmlinger et al, 1997;Lardner, 2001) and there is experimental observations of higher acid concentration near the region of the interstitial gap (Dellian et al, 1996;Helmlinger et al, 1997;Martin and Jain, 1994). A cause for this pH gradient could be a large region of necrosis (Gatenby and Gawlinski, 1996).…”

Potential of Diallyl Sulfide Bearing pH-Sensitive Liposomes in Chemoprevention Against DMBA-Induced Skin Papilloma

“…The operative mechanism seems to form the basis of the observed higher efficacy of pH sensitive liposomes over egg PC neutral liposomes (41,42). In addition, the higher effectiveness of pH-sensitive liposome can also be justified on the premise that sites of greatest acidity in tumors are often most distant from the tumor microvasculature, incidentally conventional liposomes often fail to reach such locations (43,44,45), while pH-sensitive liposomes overcome this problem.…”