Syntheses and biological activities of N-alkyl- and N-alkenylcarbamoyl phospholipids.
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Animals↗
Biomedical subjects
S Nojima
Publications and source records attributed to S Nojima.
[Mediastinal seminoma--report of a case].
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Adolescent↗
Lysis of erythrocytes by phosphatidylcholine containing polyunsaturated fatty acid.
Egg yolk phosphatidylcholine liposomes induced lysis of erythrocytes from various animals. Hemolysis of human erythrocytes occurred only above 37 degrees C. The incorporation of cholesterol and dicetylphosphate into liposomes did not affect the hemolytic activity of the phosphatidylcholine liposomes. Hemolysis was inhibited by EDTA and serum albumin. Liposomes prepared from rat liver phosphatidylcholine or those from synthetic dilinoleoylglycerophosphocholine are also hemolytic to human erythrocytes, whereas dimyristoyl- and dioleoylglycerophosphocholines are not. These findings indicate that the polyunsaturated fatty acid residues might be very important for the hemolytic activity of these phosphatidylcholine liposomes.
Adult↗
Electron microscopic study on the structures formed by mixtures containing synthetic glyceroglycolipids.
Structures of aqueous dispersions prepared from monoglycosyldiglycerides and from mixtures of monoglycosyldiglyceride and phosphatidylcholine were studied by freeze-fracture electron microscopy. Aqueous dispersions of glucosyl or galactosyl dipalmitylglycerol formed lamellar structures when quenched both from below and above the gel-liquid crystalline phase transition temperature. With mixtures of monoglycosyl dipalmitylglycerol and dipalmitoylphosphatidylcholine, tubular structures could be observed in the extended bilayer structures. Diglucosyl dipalmitylglycerols showed only a smooth fracture surface, however, when mixed with dipalmitoylphosphatidylcholine. In the fractured face of dispersions composed of egg yolk phosphatidylcholine and glucosyl dipalmitylglycerol, particles having a diameter of 3-6 nm, instead of tubular structures, were observed, suggesting that the occurrence of tubular structure may depend on the fatty acid compositions of the mixtures. A mixture of dipalmitoylphosphatidylcholine and galactosylceramide did not show any distinct tubular or globular structures on the fractured face. These findings indicate that structure in the polar group of molecules as well as structure in the non-polar group may be important for the formation of a non-bilayer, tubular structure.
Chemical Phenomena↗
Partial purification and properties of phospholipase A2 from rat liver mitochondria.
Phospholipase A2 of rat liver mitochondria was purified approximately 1,400-fold by extraction with KCl, and chromatographies on a Sephadex G-75 column and a diacyl-glycerophosphocholine-Sepharose affinity column. The purified enzyme was very labile when incubated either at 37 degrees C or 0 degrees C, and lost its activity within a few hours. Phospholipids or detergents in the solution protected the enzyme against inactivation. The purified phospholipase A2 preferentially hydrolyzed phosphatidylethanolamine, especially if it contained linoleic acid. The enzyme showed low activity for phosphatidylcholine or phosphatidylinositol.
Animals↗
Release of vesicles containing acetylcholinesterase from erythrocyte membranes by treatment with dilauroylglycerophosphocholine.
The shedding of acetylcholinesterase-enriched vesicles from erythrocytes of various species of animals occurred when cells were treated with C12:0PC. The response was observed shortly after a morphological change of erythrocytes without any accompanying detectable K+ leakage or hemolysis. The vesiculation was inhibited by the presence of serum albumin or by the incorporation of cholesterol into C12:0PC liposomes, indicating that the insertion of C12:0PC into the erythrocyte membrane causes the vesiculation. The ratio of C12:0PC to total phospholipid determined in vesicle fractions was almost the same as that observed in non-hemolyzed cell fractions. This finding suggests that the vesicles were not shed from portions of membranes rich in C12:0PC. The vesicles showed similar characteristics to those generated by ATP depletion; their diameter is 150-200 nm and they are enriched with acetylcholinesterase activity. Erythrocytes became denser when they lost acetylcholinesterase activity on treatment with C12:0PC.
Acetylcholinesterase↗
Interaction of concanavalin A with spin-labeled glycolipid incorporated into liposomes.
Using a synthetic glycolipid derived from maltotetraose and a spin-labeled fatty acid, the lateral distribution and molecular motion of the spin-labeled glycolipid on phosphatidylcholine liposomes in the presence and absence of concanavalin A were examined. When the spin-labeled glycolipid was added to preformed egg yolk phosphatidylcholine-dicetyl phosphate (molar ratio, 10 : 1) liposomes, most of the spin-labeled glycolipid molecules could be incorporated into liposomes as shown by their concanavalin A-induced agglutination. Concanavalin A also caused a change in line width of the ESR signal of liposome-bound spin-labeled glycolipid, whereas the overall splitting value 2A parallel did not change significantly. It is suggested that the binding of glycolipid molecules to concanavalin A increased the interactions among the radicals of the probe but that the mobility of the acyl chain off glycolipids was not affected. These signal changes were also observed with succinyl-concanavalin A. However, in contrast to concanavalin A, no appreciable agglutination of liposomes could be induced by the latter concanavalin A derivative. Both the agglutination of liposomes and the change in line width of the ESR signal were completely inhibited by alpha-methyl-D-mannoside.
Agglutination Tests↗
Hemolytic activities of various phospholipids and their relation to the rate of transfer between membranes.
The correlation between hemolytic activities of various phospholipids and their incorporation into membranes was studied. Short chain phosphatidylcholines can be spontaneously transferred between liposome-liposome and between liposome-erythrocyte membrane. The order of the rate of transfer is as follows: C10:0PC greater than C12:0PC much greater than C14:0PC. These findings indicate that the transfer process may be favored by the short fatty acyl chain of phosphatidylcholines. The transfer of C12:0PC was observed in the direction from egg yolk PC liposome to egg yolk PC liposome, from C12:0PC liposome to erythrocyte membrane, from erythrocyte membrane to egg yolk PC liposome, and from erythrocyte membrane to erythrocyte membrane, but not in the direction from egg yolk PC liposome to erythrocyte membrane or from erythrocyte membrane to C16:0PC liposome. The accumulation of a certain amount of C8:0PC, C10:0PC, or C12:0PC on the erythrocyte membrane caused hemolysis. The order of rate of hemolysis is C8:0PC greater than C10:0PC greater than C12:0PC. C8:0PC induced rapid hemolysis only when the concentration was relatively high; 100-200 microM C8:0PC and 5-10 microM C10:0PC, C11:0PC, or C12:0PC were required for 50% hemolysis. The distribution coefficient of C8:0PC between membranes and buffer may be small as compared to those of C10:0PC and C12:0PC. The hemolytic activity of PC may depend both on the rate of transfer and on the distribution coefficient of the molecule between membrane and buffer. Hemolytic activity of dilauroylphospholipids was also affected by head group modification. The order of hemolytic activity is as follows; dilauroylglycerophospho-choline, -serine greater than -dimethylethanolamine much greater than -ethanolamine. The weak hemolytic activity of dilauroylglycerophospho-dimethylethanolamine and -ethanolamine may be due to poor transfer of these lipids to erythrocytes.
Erythrocyte Membrane↗
Mechanism of human erythrocyte hemolysis induced by short-chain phosphatidylcholines and lysophosphatidylcholine.
The incorporation and accumulation of a certain amount of short-chain phosphatidylcholine or lysophosphatidylcholine into lipid bilayers of erythrocyte membranes is the first step causing membrane perturbation in the process of hemolysis. Accumulation of dilauroylglycerophosphocholine into membranes makes human erythrocytes "permeable cells"; Ions such as Na+ or K+ can permeate through the membrane, though large molecules such as hemoglobin can not. The "pore" formation was partially reproduced in liposomes prepared from lipids extracted from human erythrocyte membranes; C12:0PC induced the release of glucose from liposomes but did not significantly induce the release of dextran. It was suggested that the phase boundary between dilauroylglycerophosphocholine and the host membrane bilayer or dilauroylglycerophosphocholine rich domain itself behaves as "pores." Erythrocytes could expand to 1.5 times the original cell volume without any appreciable hemolysis when incubated with C12:0PC at 37 degrees C. The capacity of the erythrocytes to expand was temperature dependent. The capacity may play an important role in the resistance of the cells against lysis. The "permeable cell" stage could be hardly observed when erythrocytes were treated with didecanoylglycerophosphocholine and lysophosphatidylcholine. Perturbation induced by accumulation of didecanoylglycerophosphocholine or lysophosphatidylcholine may cause non specific destruction of membranes rather than formation of a kind of "pore."
Cell Membrane Permeability↗
Hydrolysis of phospholipids by phospholipase A2 in intact membranes of sheep erythrocytes.
We can detect phospholipase A activity in non-hemolyzed sheep erythrocytes, using dilauroylglycerophosphocholine as an exogenous substrate. Only substrates such as dilauroylglycerophosphocholine, which can be incorporated into membranes, could be hydrolyzed by the enzyme, egg phosphatidylcholine being only slightly sensitive to the enzyme in the absence of detergent. Egg phosphatidylcholine is not hydrolyzed even in the presence of dilauroylglycerophosphocholine at the concentration used routinely in the present experiment, indicating that dilauroylglycerophosphocholine itself does not behave as a detergent under the present experimental conditions. Exogenous calcium ions are necessary for the activity, but it was abolished by EDTA. This finding suggests that the Ca2+ binding site of the enzyme may be exposed on the outer surface of the erythrocyte membrane.
Animals↗
Purification and characterization of human serum C-reactive protein.
A simple and rapid purification method for human serum C-reactive protein (CRP) was developed. CRP was strongly adsorbed on a DEAE-cellulose column and was easily separated from other serum proteins. CRP was purified approximately 1,000-fold with a high yield (50%). The final preparation showed a single band as judged by SDS-polyacrylamide gel electrophoresis, polyacrylamide gel disc electrophoresis, and polyacrylamide gel isoelectric focusing. The fluorescence of the complex of CRP and 8-anilino-1-naphthalene sulfonate (ANS) changed with change of the pH, suggesting that CRP may show pH-dependent conformational change. This finding could account for the peculiar behavior of the protein in isoelectric focusing; it shows an isoelectric point of 7.4 when the starting pH is 7.0, whereas it shows two isoelectric points, 5.3 and 7.4, when the starting pH is 5.5. Ca2+-dependent change of the fluorescence of the complex of CRP and ANS was also detected. These results suggest a pH- and Ca2+-dependent conformational change of CRP.
Amino Acids↗
HVJ-mediated fusion between erythrocyte membranes and liposomes containing glycophorin.
The HVJ-mediated interaction of liposomes containing glycophorin with human erythrocytes was studied. A ternary complex of erythrocyte-HVJ-liposome was formed on incubation at 4 degrees C. Spin-labeled phosphatidylcholine and spin-labeled galactosylceramide, both of which were incorporated into liposomes, were effectively transferred into erythrocytes upon shifting-up of the incubation temperature to 37 degrees C. This finding indicates that fusion between glycophorin liposomes and erythrocytes occurs in the presence of HVJ. Fusion could be also inferred from the transfer of radio-labeled lipids embedded in the liposomal membranes to erythrocyte membranes as well as uptake of solutes entrapped in the aqueous space of the liposomes by erythrocytes. The total amount of liposomes fused with erythrocytes depended on the glycophorin content of liposomes and the amount of HVJ added. No transfer was observed when trypsinized HVJ was used in place of HVJ, suggesting that the fusion is F protein dependent.
Animals↗
Interaction of hapten-sensitized liposomes with cells bearing hapten-specific receptors.
The binding of liposomes sensitized with 2,4-dinitrophenyl-6-N-aminocaproylphosphatidylethanolamine (DNP-Cap-PE) to MOPC-315 cells, which secrete and bear on their surfaces anti-DNP immunoglobulins, was studied. The binding was affected by cholesterol content, phospholipid composition and hapten density of liposomes: The binding of distearoylphosphatidylcholine liposomes sensitized with 5 mol% hapten to the cells increased with increasing cholesterol content in liposomes. The amount of liposomes composed of phospholipid with a higher transition temperature (such as distearoylphosphatidylcholine), which bound to MOPC-315 cells, was much higher than that of liposomes composed of phospholipid with a lower transition temperature (such as egg yolk phosphatidylcholine). The amount of distearoylphosphatidylcholine liposomes containing equimolar cholesterol, which bound to the cells at 0 degrees C, increased with increasing amount of the hapten in liposomes up to 2.5 mol%. The binding became maximum at 2.5 mol% and decreased with higher hapten density in liposomes. The immunogenicity of hapten-sensitized liposomes is known to be affected by the liposomal composition such as cholesterol content, phospholipid composition and hapten density. This model study suggests that the binding of liposomes to cells is important for expressing the immunogenicity of hapten-sensitized liposomes.
Animals↗
Identification and cloning of the gene coding for lysophospholipase L2 of E. coli K-12.
E. coli bearing hybrid plasmid pKOl (Oeda et al. (1981) Mol. Gen. Genet. 184, 191-199) expressed a large amount of lysophospholipase L2 activity. When a mutant which was defective in lysophospholipase L2 activity was transformed with plasmid pKOl, it overproduced lysophospholipase L2 activity. The gene responsible for the lysophospholipase L2 activity was designated as pld B. On the same hybrid plasmid another gene (pld A) coding for detergent-resistant phospholipase A (DR-phospholipase A) was also identified. These facts together with the results of a Pl transduction experiment revealed that the pld B gene must be between the pld A and met E genes on the E. coli chromosome.
Cloning, Molecular↗
The metabolism of platelet activating factor in platelets and plasma of various animals.
Metabolism of platelet-activating factor (PAF) in rabbit plasma or in rabbit platelets was studied. [C3H3]-Labeled PAF was degraded into lysoPAF and choline in plasma. An agonist of PAF, NT071 was not degraded in the plasma. Albumin protects the degradation of PAF in plasma deprived of albumin but not the degradation of lysoPAF. These findings indicate that PAF may be metabolized in plasma by acetylhydrolase and then by lysophospholipase D. PAF was converted to phosphatidylcholine (PC) in washed rabbit platelets. The radioactivities in PC was recovered in the fraction of lysoPC after mild alkaline treatment, suggesting that the product is 1-alkyl-2-acyl-glycerophosphocholine. The binding of PAF and lysoPAF to rabbit platelets, rabbit erythrocytes and liposomal membranes were next examined. The binding of PAF to various membranes was inhibited by albumin. Albumin also suppressed the activation of platelets by PAF. A monomeric form of PAF, which is free from albumin, may react with target cell membrane and also be degraded by catabolic enzymes. The binding of lysoPAF to platelets, erythrocytes and liposomes was more effectively inhibited by albumin than that of PAF. The affinity of PAF to lipid bilayers may be higher than that of lysoPAF.
Animals↗
Visual-evoked potentials elicited by laser speckle patterns. Studies on the characteristics and assessment of visual function in patients with ocular media opacities.
Visual-evoked potentials (VEPs) were recorded using a laser speckle pattern. Stimulation with a speckle pattern was elicited either by pattern appearance-disappearance or by pattern shift. The VEPs obtained by this method were similar in properties to the previous pattern VEPs that were obtained either by pattern appearance-disappearance or by pattern reversal. Patients in whom dense and diffuse ocular media opacity defied measurement by the interferometric visual acuity method were studied to test if the speckle pattern generated by diffusion from lens opacity itself could act as a stimulus for obtaining VEPs. It is concluded that the present method enables one to obtain a reliable VEP and to assess the visual function of the retino-cortical system, even in patients with mature cataracts.
Adult↗
Electron microscopic study on the interaction of Sendai virus with liposomes containing glycophorin.
The interaction of liposomes containing glycophorin, a major sialoglycoprotein of human erythrocytes, with Sendai virus was studied by freeze-fractures and negative staining electron-microscopy. Viral envelopes were absorbed on liposomal membranes at 0 degrees C. When the temperature was shifted up to 37 degrees C, the viral envelopes fused with the liposomal membranes (envelope fusion). Particles representing viral membrane components formed clusters on liposomal membranes after incubation for more than 1 h at 37 degrees C.
Freeze Fracturing↗