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Morrison, George H.; Freiser, Henry

doi:10.1021/ac60211a008

Cited by 35 publications

(16 citation statements)

References 117 publications

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“…The specific activity of all three enzymes was calculated as Aumol of inorganic phosphate (25) released per mg of protein (26) per hr. All plasma membrane and SV fractions were also assayed for total cholesterol (27) and total phospholipids (28). For fluorescence measurements of the isolated plasma membrane and SV fractions, glycerol and sucrose were removed by a 12-hr dialysis against Pi/NaCl.…”

Section: Methodsmentioning

confidence: 99%

Decreased microviscosity of membrane lipids in leukemic cells: Two possible mechanisms

Petitou

Tuy

Rosenfeld

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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Steady-state fluorescence polarization studies with the fluorescent lipid probe 1,6-diphenyl 1,3,5-hexatriene were done to determine the degree of microviscosity of cellular membrane lipids and serum lipoproteins in human normal donors and leukemic patients. The results show a marked decrease in microviscosity of cellular membrane lipids in both intact lymphocytes and isolated cellular plasma membranes obtained from leukemic patients in clinical relapse as compared to intact lymphocytes and isolated cellular plasma membranes obtained from normal donors and leukemic patients in complete clinical remission. Concomitant to these dynamic changes in cellular membrane lipids, the degree of microviscosity of lipids in the blood serum of leukemic patients in clinical relapse is markedly reduced as compared to serum obtained from normal donors and leukemic patients in complete clinical remission. Moreover, an in vitro incubation of leukemic lymphocytes with normal low density lipoproteins results in an increased microviscosity of cellular membrane lipids. In addition to the interrelation between cellular membrane lipids and serum lipoproteins, plasma membrane vesicles with a high degree of lipid microviscosity were isolated from the blood serum and pleural effusion of leukemic patients in clinical relapse. Such membrane vesicles could not be detected in normal serum. Therefore, we suggest that the two major mechanisms associated with the decreased microviscosity of membrane lipids in human leukemic cells are an abnormal exchange in lipids between the leukemic cell surface membrane and leukemic serum lipoproteins and an exfoliation of plasma membrane vesicles with a high degree of microviscosity from the cell surface of leukemic cells.The dynamic nature of a biological lipid complex can be quantitatively monitored by fluorescence polarization analysis with the aid of the fluorescent hydrocarbon probe 1,6-diphenyl 1,3,5-hexatriene (DPH) (1-7). From the recorded degree of fluorescence polarization, the degree of microviscosity of the analyzed sample can be estimated (8,9). Results obtained with this method have shown that the major parameter that determined the degree of microviscosity of lymphocyte membranes is the molar ratio of cholesterol to phospholipids, the two main lipid components of membranes in mammalian cells (10,11 the main characteristic that determines this dynamic difference originates from a significant decrease in the molar ratio of cholesterol to phospholipids in the plasma membrane lipid core of leukemic lymphocytes (10). Recently, two hypotheses have been advanced to explain these differences between normal and leukemic lymphocytes: exchange of lipids between cellular membranes and serum lipoproteins (1, 17), and exfoliation of plasma membrane vesicles from the leukemic cells with a high ratio of cholesterol to phospholipids (10, 18). Our main interest in the present study was to determine the degree of microviscosity of lymphocyte membrane lipids and of serum lipids in normal donors and leukem...

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Section: Methodsmentioning

confidence: 99%

Decreased microviscosity of membrane lipids in leukemic cells: Two possible mechanisms

Petitou

Tuy

Rosenfeld

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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“…In light of the results obtained, the chromium(VI) is extracted from acidic chloride media and hydrochloric acid media into TPB as HCrO3Cl. 19,20 The probable extraction mechanism in chloride acid media may be as follows:…”

Section: Effect Of the Tributylphosphate Concentrationmentioning

confidence: 99%

Hexavalent Chromium Recovery by Liquid-Liquid Extraction with Tributylphosphate from Acidic Chloride Media

et al. 2003

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“…Untrapped dye was removed by gel exclusion chromatography on Sephadex G-50. Phospholipid concentrations were determined by phosphate assay [29]. Liposomes were mixed with polymers and gently stirred overnight at 4³C to form liposome-polymer complexes.…”

Section: Liposome Preparation Characterization and Leakage Assaymentioning

confidence: 99%

Copolymers of N‐isopropylacrylamide can trigger pH sensitivity to stable liposomes

1998

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Stable liposomes were rendered pH-sensitive by complexation to a polymer that undergoes marked temperatureand pH-dependent water solubility changes. The N-isopropylacrylamide-methacrylic acid copolymer was prepared with or without octadecyl acrylate. At pH below the phase transition of the polymer, egg phosphatidylcholine liposomes quickly released a part of their contents only when associated with the octadecyl aliphatic chain grafted polymer at 37³C. Similarly, sterically stabilized liposomes also quickly released a significant part of the entrapped fluorescent markers at pH 5.5^4.9, values corresponding to those of endosomes/lysosomes. This new pH-sensitive liposome-polymer system may further improve the efficiency of liposomal drug delivery.z 1998 Federation of European Biochemical Societies.

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Extraction

Cited by 35 publications

References 117 publications

Decreased microviscosity of membrane lipids in leukemic cells: Two possible mechanisms

Decreased microviscosity of membrane lipids in leukemic cells: Two possible mechanisms

Hexavalent Chromium Recovery by Liquid-Liquid Extraction with Tributylphosphate from Acidic Chloride Media

Copolymers of N‐isopropylacrylamide can trigger pH sensitivity to stable liposomes

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