The detection of early gastric cancer that often develops asymptomatically is crucial for improving patient survival. The photodynamic diagnosis (PDD) of gastric cancer using 5-aminolevulinic acid/protoporphyrin IX (5-ALA/PpIX) has been reported in several studies. However, the selectivity of PDD of gastric tumor is poor with often false-positive results that require the development of new methods to improve PDD for early gastric cancer. Therefore, a measure of the complexity of gastric microcirculation (multi-scale entropy, MSE) and the detrended fluctuation analysis (DFA) were applied as additional tools to detect early gastric cancer in rats.In this experimental study, we used our original model of metastatic adenocarcinoma in the stomach of a rat. To induce a gastric tumor, we used a long-term combination (for 9 months, which is 1/2 of the life of rats) of two natural factors, such as chronic stress (overpopulation being typical for modern cities) and the daily presence of nitrites in food and drinks, which are common ingredients added to processed meat and fish to help preserve food. Our results clearly show that both methods, namely, PDD using 5-ALA/PpIX and complexity/correlation analysis, can detect early gastric cancer, which was confirmed by histological analysis. Pre-cancerous areas in the stomach were detected as an intermediate fluorescent signal or MSE level between normal and malignant lesions of the stomach. However, in some cases, PDD with 5-ALA/PpIX produced a false-positive fluorescence of exogenous fluorophores due to its accumulation in benign and inflammatory areas of the mucosa. This fact indicates that the PDD itself is not sufficient for the correct diagnosis of gastric cancer, and the use of additional characteristics, e.g., complexity measures or scaling exponents, can significantly improve the diagnostic accuracy of PDD of gastric cancer that should be confirmed in further clinical studies and applications.

Malignant gliomas are highly invasive tumors that use the cerebral vessels for invasion due to high vascular fragility of the blood–brain barrier (BBB). On one hand, glioma is characterized by the BBB disruption, on the other hand, drug brain delivery via the BBB is a big challenge in glioma therapy. The limited information about vascular changes associated with glioma growth is a reason of slow progress in prevention of glioma development. Here, we present in vivo and ex vivo study of the BBB disruption and glioma cells (GCs) migration in rats using fluorescence and confocal microscopy. We uncovered a local breach in the BBB in the main tumor mass but not within the border of normal and malignant cells, where the BBB was impermeable for high weight molecules. The migration of GCs were observed via the cerebral vessels with the intact BBB that was associated with macrophages infiltration. The mechanisms underlying glioma progression remain unknown but there is an evidence that the sympathetic nervous system (SNS) via activation of vascular beta2-adrenoreceptors (B2-ADRs) can play an important role in tumor metastasis. Our results clearly show an increase in the expression of vascular B2-ADRs and production of the beta-arrestin-1 - co-factor of B2-ADRs signaling pathway in rats with glioma. Pharmacological blockade of B2-ADRs reduces the BBB disruption, macrophages infiltration, GCs migration and increases survival rate. These data suggest that the blockade of B2-ADRs may be a novel adjuvant therapeutic strategy to reduce glioma progression and prevent metastasis.