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Results for “Capillary Permeability”

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At least 433 records · Page 24Linked to original sources
PubMed1989

[Ultrastructural study of capillary permeability of liposome-encapsulated cisplatin in an experimental rat brain tumor model].

The anticancer chemotherapeutic agent cisplatin (cis-diamminedichloroplatinum) has several disadvantages, including extreme nephrotoxicity, rapid binding to plasma proteins, and poor penetration into the central nervous system. Liposomes would seem to be suitable as carriers of cisplatin to brain tumors. This ultrastructural study was undertaken to identify the capillary permeability of liposome-encapsulated cisplatin in a rat brain tumor model. Brain tumors were induced transplacentally with a single intravenous dose of 50 mg/kg of ethylnitrosourea (ENU). One ml of liposome-encapsulated cisplatin and ferritin prepared from phosphatidylcholine and cholesterol (molar ratio 7:2) was administered via the carotid artery to rats with ENU-induced brain tumors. The tumor platinum content and that of the contralateral hemisphere were assayed by flameless atomic absorption spectrometry. The presence of ferritin-bearing liposomes was demonstrated by electron microscopy of brain capillary endothelium as well as tumor cells. Thirty minutes after drug administration, the average dry-weight platinum concentrations were 3.98 +/- 0.50 micrograms/g within the intracerebral tumors and 0.72 +/- 0.24 micrograms/g in the contralateral hemispheres. Electron microscopic ultrastructural study, which can distinguish ferritin-bearing liposomes from cell materials, demonstrated the presence of liposomes containing ferritin in both cell surface folds and capillary endothelial cells and also within tumor cells. An enlarged electron micrograph of a liposome with a diameter of approximately 0.2 micron suggested the presence of ferritin molecules in the lamellar structure. Liposome-encapsulated cisplatin is apparently able to pass the blood-brain barrier and should be useful in the chemotherapy of glioma.

Animals↗
PubMed1981

[Cardiovascular effects of cigarette smoke in the rat. Aortic endothelial and myocardial capillary permeability in the rat].

The permeability of aortic endothelium and myocardial capillaries was examined in 72 Sprague-Dawley rats (approximately 350 g) using the diffusion tracer peroxidase. Animals were subjected to cigarette smoke for periods of 1 day (acute effects), 2 weeks (sub-acute effects) and 15 weeks (chronic effects) and were sacrificed 5 minutes or 8 hours after smoking. Peroxidase was not generally present at the sub-endothelial level in the aortic endothelium of control animals and sham-smokers. However, in smokers, the increase in peroxidase permeability is proportional to the smoking period. Moreover, in these smokers we observed junctional and subendothelial vacuolar dilatations which correspond to degenerative morphologic changes. Cigarette smoke has a different effect on the right ventricle. Endothelial permeability of the myocardial capillaries increases in animals subjected to cigarette smoke for 1 day and those who smoked for 2 weeks sacrificed 5 minutes after smoking. This increase in permeability is not related to the significant morphologic changes observed in the myocardium and endothelial capillaries. However, the myocardial endothelial capillaries, the sub-endothelial space and the adjacent interstitial space were generally free of peroxidase in animals subjected to cigarette smoke for 15 weeks and in those smoking for 2 weeks sacrificed 8 hours later. An adaptive phenomenon to the effects of cigarette smoke appear to exist in the myocardial endothelium capillaries contrary to that which is observed in the thoracic aorta.

Animals↗