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PubMed1980

Combined effect of hypoxia and cold on the phospholipid composition of lung surfactant in rats.

The phsopholipid composition of lung tissue and lung lavage in rats exposed to acute hypoxia, chronic hypoxia, and acute and chronic hypoxia associated with cold has been estimated and compared with controls. Different fractions of phospholipids were separated by thin layer chromatography. Results showed that acute hypoxia lowered phospholipids in lung lavage but superimposition of cold lowered phospholipids both in lung tissue and lavage. In chronic hypoxia, phospholipid contents of lung tissue and lavage decreased while the addition of cold showed no further reduction in lung tissue phospholipids; on the contrary phosphatidyl choline fraction of lung lavage increased. It is concluded that the effect of hypoxia alone in lowering surfactant is related to the duration of exposure. Cold with hypoxia lowers phospholipids in the acute stage; in the chronic stage; it does not further reduce phospholipids.

Animals↗
PubMedDate not supplied

[Thyroid tissue phospholipids in different forms of pathology].

Phospholipid localization in the thyroid was studied in patients with nodose euthyroid- and diffuse-toxic goiter by means of histochemistry. At the same time biochemical studies on the total amount of phospholipids and their separate fractions were carried out. The maximum phospholipid number was seen in C-cells of patients with all the forms of nodose and diffuse-toxic goiter and in the control group. The C-cell amount in the nodes of the thyroid with pronounced lymphoid infiltration and in the tissue of diffuse-toxic goiter was 5 to 10 times higher comparatively to that of the controls. The total phospholipid content was twice higher in nodose goiter and 3 times higher in the diffuse-toxic forms. Correlation between the increased amount of phospholipids, particularly of phosphatidylcholine, and the enhanced C-cell number was found. The near-nodose tissue is not suitable for the control, as this part of the gland undergoes functional tension, according to the total phospholipid content and the number of C-cells, enriched with phospholipids.

Autopsy↗
PubMed1980

Proteolysis of the C5b-7 complex: cleavage of the C5b and C6 subunits and its effect on the interaction of the complex with phospholipid bilayers.

The present study was conducted to gain insight into the process of assembly of the C5b-7 complex on the phospholipid bilayer. The C5b-6 complex, C7, and 2 different forms of the C5b-7 complex (the C5b-7 complex either bound to artificial phospholipid bilayers or in fluid phase) were digested with trypsin, and the resulting products were analyzed by SDS-polyacrylamide gel electrophoresis. The alpha'-chains of C5b and C6 in the C5b-6 complex and C7 were susceptible to trypsin. The formation of the C5b-7 complex from the C5b-6 complex and C7 was accompanied by alteration in susceptibility to trypsin to C7: the C7 subunit of the fluid phase complex as well as of the complex bound to phospholipid vesicles is not susceptible to trypsin. On the other hand, the alpha'-chains of C5b and C6 in the C5b-7 complex bound to phospholipid vesicles as well as in fluid phase remained accessible and susceptible to trypsin, and cleaved as in the C5b-6 complex. Upon ultracentrifugation in a sucrose density gradient, the proteolyzed C5b-7 complex in fluid phase dissociated into subunits. However, none of the subunits in the proteolyzed C5b-7 complex bound to phospholipid vesicles dissociated from vesicles upon sucrose density gradient ultracentrifugation. Thus, the molecule of the C5b-7 complex became stable and resistant to proteolytic dissociation upon binding to the phospholipid bilayer. It is proposed that each subunit of the C5b-7 complex participates in the stable interaction of the complex with the phospholipid bilayer. In addition, the possible significance of the alteration in susceptibility to trypsin of C7 associated with the formation of the C5b-7 complex is discussed.

Animals↗
PubMed1981

Phospholipid is required for the processing of presecretory proteins by detergent-solubilized canine pancreatic signal peptidase.

The ability of canine pancreatic signal peptidase to remove the signal peptide portion of presecretory proteins in a translocation-independent assay is shown to require phospholipid. Sodium deoxycholate extracts of canine pancreatic rough microsomes containing both signal peptidase and phospholipid were delipidated by gel filtration chromatography on Sepharose CL-6B equilibrated with 0.2% deoxycholate. Column fractions were assayed for signal peptidase activity both with and without the addition of ethanol-extracted soybean phospholipid at a final concentration of 1.0 mg/ml. A peak of signal peptidase activity was detected only when the fractions were assayed with added phospholipid. Phospholipid assays demonstrated that the peak of signal peptidase activity was cleanly separated from phospholipid. The ratio of protein to phospholipid in the deoxycholate extract of rough microsomes was 1.76 while that of the most active signal peptidase fractions ranged from 46.1 to 138. The peak of signal peptidase activity exhibited an apparent Stokes radius of 55 A. Highly purified preparations of phosphatidylcholine were most effective in restoring activity to delipidated signal peptidase. Phosphatidylinositol was much less effective. Phosphatidylserine, phosphatidylethanolamine, sphingomyelin, and lysophosphatidylcholine were all ineffective.

Animals↗
PubMed1982

Effect of phospholipids on alpha-1,2-mannosidase activity.

An alpha-1,2-mannosidase has been solubilized and partially purified from rabbit liver microsomes (Forsee, W. T., and Schutzbach, J. S. (1981) J. Biol. Chem. 256, 6577-6582). The partially purified enzyme was activated by the addition of zwitterionic phospholipids but maximal activity was found to be relatively independent of acyl chain length or degree of unsaturation. Titration of the enzyme with increasing concentrations of water-soluble and long acyl chain phospholipids demonstrated that an ordered lipid structure of either micelles or bilayers was required for alpha-mannosidase activity. Mixed micelles of Triton X-100 and zwitterionic phospholipids also activated the enzyme. The concentration of phospholipid in the mixed micelles required for activation was dependent upon acyl chain length, but maximal activity was unaffected by this parameter. The addition of negatively charged phospholipids not only failed to activate the enzyme but also inhibited alpha-mannosidase activity in the presence of zwitterionic phospholipids. Inhibition by negatively charged phospholipids was pH dependent with maximal inhibition at pH values of 6.0 or lower. These results suggest that the activity of the alpha-1,2-mannosidase could be subject to modulation by the composition and structure of the microsomal membranes.

Animals↗
PubMedDate not supplied

[Changes in the fatty acid composition of phospholipids during the growth process of microscopic fungi of the family Entomophthoraceae].

The fatty acid composition of phospholipids and its changes during growth of two cultures of microscopic fungi belonging to the family Entomophthoraceae have specific peculiarities. Fatty acids in the composition of phospholipids contain from 10 to 20 carbon atoms in the chain; unsaturated fatty acids prevail among them, and constitute about 60% in the phospholipids of Ent. coronata 1932 and about 70% in the phospholipids of Ent. conica 1716. The content of arachidonic acid in the phospholipids of the both cultures is high (up to 17%). The fatty lipids of phospholipids are actively involved in metabolism in the process of the fungal growth, particularly in Ent. coronata 1932 which is characterized by a higher level of metabolism. The total degree of unsaturation of phospholipids changes only slightly during the growth of the two cultures.

Chemical Phenomena↗
PubMed1981

[Changes in the phospholipid content of blood in diabetes mellitus before and after complex treatment at the Dzhermuk health resort].

The studies were carried out at Dzhermuk clinical sanatorium in 53 patients with moderate and severe diabetes mellitus. Qualitative and quantitative phospholipid content of the whole blood and total cholesterol and beta-lipoproteins of the blood serum were determined. The patients show the constant qualitative content of the blood phospholipids and marked quantitative variations in several phospholipid fractions along with a relatively stable condition of other lipid metabolism indices. The degree of phospholipid fraction quantitative disorders is dependent on the patient's age and diabetes mellitus severity, lipid-lipoid ratio tending to decrease in the neutral phospholipid per cent content of the total phospholipid sum. The treatment at the health resort is accompanied by normalization or a tendency to normalize the blood phospholipid quantitative content and lipid-lipoid ratio. The treatment efficiency is directly dependent on the patient's age, duration and severity of the disease.

Adult↗
PubMed1980

Diacyl, alkenyl, and alkyl ether phospholipids in ejaculated, in utero-, and in vitro-incubated porcine spermatozoa.

The phospholipids of porcine spermatozoa were analyzed by a hydrolytic procedure directly after ejaculation, and after incubation for 120 min in vitro or in ligated uterine segments of females with induced estrus. Total phospholipid content of ejaculated sperm was 65.7 micro g lipid P per 10(9) sperm, of which 41% was alkyl ether and 23% was alkenyl ether glycerophospholipid. All of the ether phospholipids were choline and ethanolamine glycerophospholipids. In order of decreasing amount (% of total phospholipid), the phospholipids were choline and ethanolamine glycerophospholipids (49.9 and 28.2), sphingolipid (10.6), cardiolipin (5.5), phosphatidylinositol (2.3), phosphatidic acid (1.5), phosphatidylserine (1.2), and phosphatidylglycerol (0.8). Phosphorus-containing sphingolipid separated into two components during thin-layer chromatography. Sphingosine was the only long-chain base identified in either band. Major fatty acids in the band with lower R(f) were 16:0 (56%), 20:0 (23%), and 18:0 (11%) plus smaller amounts of 14:0, 18:1, and 22:0, while those in the band with higher R(f) were 14:0 (30%), 16:0 (45%), and 18:1 (12%) plus smaller amounts of 18:0, 20:0, and 22:0. Choline was the only water-soluble base present in the lower R(f) sphingomyelin while ethanolamine was prevalent in the higher R(f) component. Incubation of washed spermatozoa in Ca(2+)-free Ringer-fructose at 37 degrees C for 2 hr produced no significant change in the level of any of the phospholipids. Incubation of washed sperm in the uterus for 2 hr, in the presence of oviductal secretions, produced an increase in phosphatidylcholine from 7.2 to 10.2 micro g lipid P per 10(9) sperm.-Evans, R. W., D. E. Weaver, and E. D. Clegg. Diacyl, alkenyl, and alkyl ether phospholipids in ejaculated, in utero-, and in vitro-incubated porcine spermatozoa.

Animals↗
PubMed1980

Comparative study of the phospholipid composition of plasma membranes isolated from rat primary hepatomas induced by 3'-methyl-4-dimethylaminoazobenzene and from normal growing rat livers.

Plasma membranes (PM's) were isolated from primary hepatomas induced in Wistar rats by 3'-methyl-4-dimethylaminoazobenzene, from nonhepatomal regions of the same rat livers, and also from various normal rat livers, including the resting and regenerating livers of adult rats and developing livers of postnatal rats. Phospholipid analyses of these PM preparations revealed the following differences in the hepatoma PM in comparison with those of the PM of normal adult resting livers: (a) decrease in the content of total phospholipids; (b) large increase in plasmalogen content; (c) relative increase of sphingomyelin and ethanolamine phospholipids, and the decrease of choline phosphoglycerides, i.e., decrease of the ratios of choline phosphoglycerides to choline phosphosphingoside and of choline-containing phospholipids to ethanolamine-containing phospholipids; (d) decrease in phosphatidylserine and phosphatidylinositol. The phospholipid composition of the PM's from normal growing livers showed definite decreases in phosphatidylserine and sphingomyelin and increases in ethanolamine phospholipids; however, no significant alteration was observed in plasmalogen content in comparison to the PM of normal adult resting livers. The PM from the nonhepatomal regions of the hepatoma-bearing livers did not show those differences observed in hepatoma PM.

Animals↗
PubMed1993

Mobilization of acyl chains from endogenous cellular phospholipids into cholesteryl esters during foam-cell formation in mouse peritoneal macrophages.

We previously showed that phosphatidylserine-containing liposomes (phosphatidylserine liposomes) are effectively metabolized and induce foam-cell formation in cultured macrophages (Nishikawa, K., Arai, H. and Inoue, K. (1990) J. Biol. Chem. 265, 5226-5231). When cultured mouse peritoneal macrophages were incubated with phosphatidylserine liposomes of different cholesterol content, cholesteryl esters were formed in the cells in proportion to the cholesterol content of the liposomes added to the culture. Cholesteryl esters were formed only when the cells took up more than a certain amount of cholesterol (approx. 160% above the basal cell level). Fatty acyl moiety derived from the exogenous phospholipids were utilized preferentially for cholesteryl ester formation. Once cholesterol as an acceptor is exhausted within cells, the acyl chain may be utilized for triacylglycerol formation. Not only exogenous lipid acyl chains but also endogenous phospholipid acyl chains were also utilized for cholesteryl ester and triacylglycerol formation under the present conditions, since the radioactivity in phospholipids was incorporated into both cholesteryl esters and triacylglycerols in macrophages whose endogenous phospholipids had been prelabeled with radioactive fatty acids. Among phospholipid classes, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol served as the acyl donor, whereas sphingomyelin and cardiolipin did not. Mobilization of acyl chains from endogenous phospholipids to the neutral lipid fraction was also observed during foam-cell formation induced by acetyl low-density lipoprotein. The substance(s) produced within cell in the process of foam-cell formation may trigger the acyl chain mobilization from endogenous phospholipids.

Animals↗
PubMed1995

"Anticardiolipin" autoantibodies recognize beta 2-glycoprotein I in the absence of phospholipid. Importance of Ag density and bivalent binding.

"Anticardiolipin" autoantibodies (aCL) bind to anionic phospholipids only in the presence of beta 2-glycoprotein I (beta 2GPI), a phospholipid-binding plasma protein. The exact role of beta 2GPI in the antigenic specificity of these autoantibodies is unclear, however. Experiments were performed to determine whether aCL recognize beta 2GPI in the absence of phospholipid or neo-Ags formed as a consequence of the beta 2GPI-phospholipid interaction. Although aCL+ IgG fractions did not bind to beta 2GPI alone in ELISAs that used standard polystyrene immunoassay plates, significant specific binding was detected when beta 2GPI was coated on gamma-irradiated ("high binding") polystyrene plates. This difference was associated with the greater density of beta 2GPI immobilized on the gamma-irradiated plates. Fab' fragments of patient IgG demonstrated little or no binding to immobilized beta 2GPI in ELISA, indicating a critical role for Ab bivalency. Inhibition studies of three aCL+ IgG fractions confirmed their specificity for beta 2GPI and demonstrated low affinity binding to fluid-phase beta 2GPI (Kd values of approximately 10(-5) M). aCL binding to beta 2GPI was not a result of phospholipid contamination of the assays, as determined by microphosphate assay and by lipid extraction of IgG and beta 2GPI preparations. In summary, these experiments indicate that IgG aCL are intrinsically low affinity Abs to beta 2GPI. Ab binding to beta 2GPI on a microtiter plate or anionic phospholipid membrane is dependent upon the marked increase in avidity provided by engagement of both Ag binding sites of a given IgG molecule. The data support the hypothesis that phospholipid-bound beta 2GPI is the physiologic target of aCL.

Antibodies, Anticardiolipin↗
PubMed1994

Polyamine inhibition of transbilayer movement of plasma membrane phospholipids in the erythrocyte ghost.

The resting plasma membrane of circulating blood cells demonstrates an asymmetric distribution of the phospholipid classes across the bilayer that is altered during cellular activation. To better understand the mechanisms governing transbilayer distribution of phospholipids, studies were conducted using the erythrocyte ghost, in which plasma membrane leaflet distribution of phospholipids can be readily probed. Preparation of ghosts by hypotonic lysis at increasingly high dilution markedly enhanced (up to 10-fold) calcium-induced (50-500 microM) transbilayer movement of phospholipids. The enhanced transbilayer movement was assessed by translocation of exogenously added sn-2-[6[(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]caproyl]-labeled phosphatidylcholine and phosphatidylserine from the plasma membrane outer leaflet to the inner leaflet and vice versa, as well as transbilayer movement of endogenous phosphatidylserine to the outer leaflet. It was found that phospholipid movement was bidirectional and also nonspecific with regard to polar head group. It was further demonstrated that preparation of ghosts at increasing dilution resulted in depletion of cellular polyamines and that physiologic replenishment of spermine, and to a lesser extent spermidine, resulted in significant inhibition (50 and 25%, respectively) of transbilayer movement of phospholipids. Replenishment of other di- and polyamines demonstrated that inhibition was not simply dependent on total cationic charge but rather on charge density and suggestive of specific interaction of the polyamines, particularly spermine, with the plasma membrane. As most cells demonstrate both a high degree of regulation in maintenance of polyamine levels and the means for facile shifts within cellular polyamine pools, it is suggested that loss of membrane asymmetry during cellular activation may be mediated in part through enhanced transbilayer movement of phospholipids due to altered polyamine-membrane associations.

4-Chloro-7-nitrobenzofurazan↗
PubMed1994

Coordination of membrane phospholipid synthesis with the cell cycle.

The formation of membrane phospholipid is coordinated with the cell cycle in a colony-stimulating factor 1-dependent macrophage cell line. Net phospholipid accumulation occurs as cells enter S phase and results from an interaction between cell cycle-dependent oscillations in the rates of phosphatidylcholine (PtdCho) biosynthesis and degradation. CTP:phosphocholine cytidylyltransferase (CT) is the rate-controlling step in PtdCho biosynthesis, and its activity is inhibited by cell cycle-dependent phosphorylation. CT phosphorylation is low in early G1, begins to rise in late G1, increases steadily through S and G2/M, and then declines precipitously as cells exit mitosis and reenter G1. CT activity increases in early G1 and then decreases steadily as the cells progress through late G1, S, and G2/M, reflecting the elevated phosphorylation state of the protein. Membrane phospholipid degradation is also periodic: the rate is rapid in G1, slows significantly during S phase, and accelerates again as cells reenter G1. The data support the hypothesis that CT dephosphorylation accelerates PtdCho synthesis in response to the increased membrane phospholipid degradation to maintain membrane phospholipid mass during G1 and that the periodic cessation of phospholipid degradation during S phase accounts for the transition to net membrane phospholipid accumulation. Inactivation of CT associated with hyperphosphorylation of the protein during G2/M likely plays a determining role in the cessation of net membrane accumulation prior to cell division.

Animals↗
PubMed1993

[Role of phospholipids in hemostasis].

This article reviews the significance of phospholipids in the haemostatic process. The plasma membranes of activated human blood platelets provide a catalytic phospholipid surface on which the "tenase" complex (factor IXa-factor VIIIa) and the "prothrombinase" complex (factor Xa-factor Va) can be assembled. The formation of a procoagulant platelet surface involves the exposure of anionic phospholipids e.g. phosphatidylserine, and is associated with shedding of microvesicles from the membranes of activated platelets. Moreover, tissue-factor, which plays a key role in blood coagulation by initiating the extrinsic coagulation pathway, requires the presence of phospholipids for optimal biological activity. The phospholipid dependency of the coagulation system explains the prolongation of phospholipid dependent clotting tests in patients with phospholipid directed antibodies such as lupus anticoagulants.

Blood Coagulation↗
PubMed1993

[The composition of fatty acids in individual classes of blood platelet phospholipids of patients with uremia].

The most important role in the formation of defects of the haemostasis in patients with uraemia is attributed to disorders of platelet activation. The important elements of phospholipid structure are saturated and unsaturated fatty acids. Five classes of phospholipids were identified in the platelets: phosphatidylethanolamine (PE), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylcholine (PC) and sphingomyelin (Sph). This paper aimed at the assessment of the fatty acid composition in individual classes of phospholipids of blood platelets in patient with uraemia. We studied 18 uraemic patients who were treated conventionally and 21 patients treated with with repeated haemodialysis. The classes of phospholipids were isolated by thin layer chromatography and the contents of fatty acids in the individual classes of of phospholipids were assessed by gas chromatography. In patients treated conventionally great differences in the contents of fatty acids in the individual classes of phospholipids were demonstrated as compared with the control group. The differences can be caused by disorders of blood plasma lipids. In general--more unsaturated fatty acids were found in the classes of phospholipids forming the outer surface of the platelets as compared to the inner surface. In haemodialysed patients the differences in the fatty acid contents compared with the control group were evidently smaller (perhaps resulting from some normalization of biochemical changes in the plasma of dialyzed patients). In this group a greater content of unsaturated fatty acids in Sph and PC was also found. The high content of unsaturated fatty acids may increase the platelet membrane fluidity and intensive lipid-protein reaction, e.g. binding of coagulation factors, so may play a role in haemostasis disturbances observed in uraemic patients.

Adult↗
PubMed1993

Labeling of the mitochondrial membrane D-3-hydroxybutyrate dehydrogenase (BDH) with new bifunctional phospholipid analogues.

D-3-Hydroxybutyrate dehydrogenase (BDH), an inner mitochondrial protein, is a well-known phospholipid dependent enzyme. It is a primary dehydrogenase of the oxidative phosphorylation system and is involved in the redox balance of the NAD+/NADH pool. The preparation of fluorescent phospholipids and newly synthesized bifunctional phospholipid analogues (fluorescent and photoactivatable) allowed us to study the structural requirement for lipid activation of the purified enzyme. This paper reports the chemical synthesis protocols to prepare these new phospholipids and their characterization. Illumination experiments of complexes between bifunctional phospholipids and BDH which lead to a cross-linked polypeptide indicate that both the polar head and the hydrophobic moiety of phospholipids interact with BDH. The bifunctional phospholipids were also tested on other lipid-binding proteins, i.e., horse cytochrome c and bovine serum albumin, and demonstrated the promising potential of this new type of photoactivatable molecules which can be followed merely by fluorescence without radioactive labeling.

Enzyme Activation↗
PubMedDate not supplied

Coagulation patterns in bovine left heart bypass with phospholipid versus heparin surface coating.

The current study was designed to evaluate tubing sets with either polymeric phospholipids or ionically bound heparin in six bovine experiments (body weight, 70 +/- 5 kg). No heparin was given systemically. Left heart bypass was started with 300 ml of clear priming solution and maintained over 6 hours (50 ml/kg/min). Coagulation studies included platelet counts, activated coagulation time (ACT), thrombin time (TT), fibrinogen (Factor I), antithrombin III (AT III), and fibrinopeptide A (FPA). Normalized platelet levels dropped from 100 +/- 12% before to 86 +/- 13% after 6 hours of left heart bypass for heparin, compared with 100 +/- 46% to 90 +/- 44% for phospholipid coating (NS). The ACT increased from 146 +/- 7 sec at 10 min to 159 +/- 16 sec after 6 hours for heparin, compared with 122 +/- 4 to 126 +/- 5 sec for phospholipid (p < 0.05). Thrombin time changed from 18 +/- 0 sec before to 19 +/- 1 sec after 6 hours for heparin, as compared with 16 +/- 1 sec to 18 +/- 1 sec for phospholipid (NS). Factor I levels decreased from 1.5 +/- 0.3 g/L to 1.3 +/- 0.1 g/L for heparin, compared with 1.5 +/- 0.2 g/L to 1.4 +/- 0.3 g/L for phospholipid. Antithrombin III levels changed from 102 +/- 26% to 91 +/- 7% for heparin, compared with 123 +/- 12% to 118 +/- 12% for phospholipid. Fibrinopeptide A levels changed from 100 +/- 60% to 130 +/- 13% for heparin, compared with 100 +/- 11% to 99 +/- 6% for phospholipid (P < 0.05). No macroscopic red clots were found in either group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

Factor Xa enhances the binding of tissue factor pathway inhibitor to acidic phospholipids.

In the present study, the interaction between tissue factor pathway inhibitor (TFPI) and phospholipids has been characterized using a microtitre plate assay. TFPI was shown to bind calcium-independently to an acidic phospholipid surface composed of phosphatidylserine, but not a surface composed of the neutral phosphatidylcholine. The interaction was demonstrated to be dependent on the presence of the TFPI C-terminus. The presence of heparin (1 U/ml, unfractionated) was able to significantly reduce the binding of TFPI to phospholipid. The interaction of TFPI with phosphatidylserine was significantly decreased in the presence of calcium, but this was counteracted, and even enhanced, following complex formation of TFPI with factor Xa prior to incubation with the phospholipid surface. Moreover, a TFPI variant, not containing the third Kunitz domain and the C-terminus, was unable to bind to phospholipid. However, following the formation of a TFPI/factor Xa-complex this TFPI variant was capable of interacting with the phospholipid surface. This indicates that the role of factor Xa as a TFPI cofactor, at least in part, is to mediate the binding of TFPI to the phospholipid surface.

Factor Xa↗