Ultrastructural basis for different pertechnetate uptake patterns by various human brain tumours.

Abstract

SUMMARY Patterns of pertechnetate uptake were correlated with ultrastructural properties of the endothelial wall in 14 human brain tumours. In tumours with reduced uptake of the radionuclide, intercellular tight junctions were observed whereas absence of intercellular tight junctions was characteristic of all tumours with an increased uptake of pertechnetate. In some tumours with increased uptake, fenestrated endothelial wall was seen while in others nonfenestrated wall was evident. We concluded that intercellular junctions and not fenestrations affect the permeability of brain tumours to pertechnetate. (Penning and Front, 1975). Two main factors govern the passage of Tc-pertechnetate from the blood into the tissue of the tumours-the vascularity of the tumour, and the permeability of the blood-brain barrier.In a previous study, uptake of pertechnetate was found to be independent of vascularity (Front, 1978). It was suggested that changes in the bloodbrain barrier, which is localised in the capillary wall, might be involved with the different rates of 99mTc-pertechnetate uptake. In the present study we extended our investigations to include the ultrastructural properties of the capillary wall. Thus, both scintigraphic assessments and electron microscopic studies were carried out on the same tumour, in order to correlate given ultrastructural features with scintigraphic patterns of pertechnetate uptake. Subjects and methodsFourteen patients whose clinical condition enabled detailed scintigraphic assessments and whose removed tumours were adequately processed for

The Effect of Cellular Microenvironment on Vessels in the Brain. Part 1: Vessel Structure in Tumour, Peritumour and Brain from Humans with Malignant Glioma

“…In the current study only 2% of vessels in tumour, and none of the vessels examined in normal white matter or peritumour, had fenestrations . This observation is consistent with qualitative observations of others in the same tumour type (Bar-Sella et al 1979, Shibata, 1989 . Although fenestrations have been described in other tumour types that have metastasized to brain (Bar-Stella et al .…”

“…Others (Long 1970, Hirano et al . 1974, Bar-Sella et al . 1979, Roy and Sarkar 1989 have reported an increase in vesicular density in tumour vessels in humans .…”

False-Negative Tc-99m MIBI Scintigraphy in Histopathologically Proved Recurrent High-Grade Oligodendroglioma

“…Increased vascular supply, disruption of the blood-brain barrier, high-grade cancer, and viability of tumor cells are decisive factors related to increased Tc-99m MIBI uptake in brain tumors (9). Although we did not evaluate cytologic and ultrastructural features of tumor cells and capillaries in relation to these uptake mechanisms, a high-grade oligodendroglioma possesses cellular and endothelial features that favor increased Tc-99m MIBI uptake (10). Finally, Tc-99m MIBI is a substrate for P-glycoprotein, a transmembrane pump that acts as a gatekeeper by expelling drugs from (cancer) cells.…”

Occludin Expression in Brain Tumors and its Relevance to Peritumoral Edema and Survival

“…Ultrastructural studies of human glioma microvessels have revealed 'open' interendothelial cell tight junctions (12). Tight junctions not only separate distinct physiological compartments, but they also confer selectivity to the transepithelial flux of molecules and ions through the intercellular spaces between the epithelial cells, the so-called paracellular pathway (13).…”