Fundamental Studies on the Cellular Uptake of Liposomes

Extended in vivo blood circulation time of fluorinated liposomes

“…Liposome clearance from the blood stream occurs as a result of interactions with blood proteins and other plasma components, resulting in liposomes opsonization followed by macrophage uptake, and/or to liposome disintegration by lipid exchange and depletion [ 1,9]. In order to reduce the MPS uptake and to enhance the circulation times of liposomes after i.v.…”

Mechanism of inhibition of lipid peroxidation by tamoxifen and 4‐hydroxytamoxifen introduced into liposomes

“…The stabilization by cholesterol (and its derivatives [15]) of membranes against lipid peroxidation is thought to occur via an interaction between the hydrophobic rings of cholesterol and the saturated, monounsaturated and polyunsaturated residues of phospholipid fatty acids [12,16], which reduces the fluidity of the membrane bilayer [8,9]. We have now shown that ergosterol, tamoxifen, 4-hydroxytamoxifen and 1713-oestradiol also exert membrane stabilizing effects against lipid peroxidation, possibly by a similar mechanism to that for cholesterol.…”

“…The ability of tamoxifen and 4-hydroxytamoxifen to stabilize membranes against lipid peroxidation beyond that achieved by cholesterol may reflect a further reduction in membrane fluidity, which is thought to be responsible for this stabilizing ability of cholesterol [8,9,12,16]. In the presence of these drugs therefore cell division may be slower as a result of reduced membrane fluidity, in agreement with the growth inhibitory properties of tamoxifen and 4-hydroxytamoxifen on oestrogen-dependent and oestrogen-independent breast tumours in vivo [5,18] and tumour cell lines in vitro [5,19,20].…”

“…Cholesterol when introduced into phospholipid liposomes [8][9][10][11] during their preparation has been reported to inhibit membrane lipid peroxidation apparently by a membrane stabilization effect [12]. Inhibition of lipid peroxidation by 17/3-oestradiol introduced into liposomes has also been reported [13].…”

Gadolinium‐labeled liposomes containing various amphiphilic Gd‐DTPA derivatives: Targeted MRI contrast enhancement agents for the liver

“…Liposomes are currently under evaluation as drug carriers for malignant diseases of the liver and infections of the reticuloendothelial system (1 I, 12). They are rapidly removed from the blood and, depending on their size and physical characteristics, concentrate either in the reticuloendothelial system ( 13) or directly in hepatocytes ( 1 4 ) . Recently liposomes have been utilized as a means to deliver various MRI contrast enhancement agents to selective sites (15)(16)(17)(18)(19).…”