Polymer migration among phospholipid liposomes

Complexation of phospholipid lipsomes with a cationic polymer, poly(N-ethyl-4-vinylpyridinium bromide) (PEVP), and subsequent interliposomal migration of the adsorbed macromolecules, have been investigated. Liposomes of two different charge types were examined: (a) a liposomal system, with an overall charge near zero, consisting of zwitterionic phosphatidylcholine (egg lecithin, EL) with added doubly anionic phospholipid, cardiolipin (CL(2-)), and cationic dihexadecyldimethylammonium bromide (HMAB(+)), in a CL(2-)/HMAB(+) charge-to-charge ratio of 1:1; (b) an anionic liposomal system composed of an EL/CL(2-) mixture plus polyoxyethylene monocetyl ether (Brij 58). Both three-component systems were designed specifically to preclude liposomal aggregation upon electrostatic association with the PEVP, a phenomenon that had complicated analysis of data from several two-component liposomes. PEVP macromolecules were found from fluorescence experiments to migrate among the charge-neutral EL/CL(2-)/HMAB(+) liposomes. In the case of anionic EL/CL(2-)/Brij liposomes, a combination of fluorescence and laser microelectrophoresis methods showed that PEVP macromolecules travel from liposome to liposome while being electrostatically associated with anionic lipids.

Coalescence of phospholipid membranes as a possible origin of anticoagulant effect of serum proteins

Interactions between phospholipid membranes (made of palmitoyloleoylphosphatidylcholine, cardiolipin and cholesterol) after addition of beta2 glycoprotein I (beta2GPI) or anti-beta2GPI antibodies or a mixture of both were studied by observing giant phospholipid vesicles under the phase contrast microscope. Both, negatively charged and neutral vesicles coalesced into complexes and adhered to the bottom of the observation chamber in the presence of beta2GPI in solution. Anti-beta2GPIs alone or previously mixed with beta2GPI caused coalescence of charged but not neutral vesicles, i.e. for neutral membranes the effect of beta2GPI was abolished by the presence of anti-beta2GPIs. Since the presence of the above adhesion mediators can prevent fragmentation of the membrane we propose a (new) possible anticoagulant mechanism for some serum proteins by preventing the release of prothrombogenic microexovesicles into circulation.

[A case of secondary syphilis with hepatitis]

Hepatitis is a rare clinical manifestation of syphilis. In this report a 50 years old male patient who was diagnosed as secondary syphilis presenting with hepatitis has been discussed. The patient was admitted to the hospital with high fever and skin rash, and his history revealed a suspected sexual contact. He indicated that he had been admitted to a health center eight months ago because of the presence of a penile wound, however VDRL (Venereal Disease Research Laboratory) test was negative at that time. Fever (39.5 degrees C), jaundice in skin and sclera, generalized macular and maculopapular skin rash including palms and soles, lymphadenopathy and hepatosplenomegaly were detected in physical examination. Laboratory tests yielded elevated erythrocyte sedimantation rate, high CRP levels and elevated liver enzyme levels, however viral hepatitis markers together with VDRL and TPHA (Treponema pallidum hemagglutination) tests were found negative. Ceftriaxone therapy was initiated because of the presence of high fever (40 degrees C) and 30 leukocyte/mm3 in urine, and the absence of bacteria in Gram staining of urine sample. However, the antibiotic therapy was discontinued since fever persisted. As the clinical signs and symptoms strongly indicated syphilis, the serological tests were repeated and VDRL positivity at 1/8 and TPHA positivity at 1/1280 titers were detected. Ceftriaxone therapy was restarted and continued for 14 days with complete cure. Since the spouse of the patient was also found VDRL and TPHA positive, she was treated with penicilin. The presentation of this case emphasized the importance of repeating the serological tests for syphilis since they might be negative in the early stages of infection. The case also indicates that syphilis should be considered in the differential diagnosis of hepatitis.

[Cytotoxic effect of lymphocytes with cardiolipin in diagnosis of acute coronary syndrome]

Cytotoxic effect of lymphocytes sensitized to cardiolipin antigen was studied in 172 patients with acute coronary syndrome. In this phenomenon effector cells were peripheral blood T-lymphocytes and target cells were erythrocytes loaded with cardiolipin antigen. It was found that cytotoxic effect of lymphocytes in these patients carries diagnostic information and can have supplementary value in difficult cases of diagnostics of this disease.

Biotinylation of glycan chains in beta2 glycoprotein I induces dimerization of the molecule and its detection by the human autoimmune anti-cardiolipin antibody EY2C9

Binding of beta2GPI (beta2 glycoprotein I), a human plasma protein, to AnPLs (anionic phospholipids) plays a key role in the formation of antiphospholipid antibodies involved in autoimmune diseases like antiphospholipid syndrome or systemic lupus erythematosus. We recently showed that binding of beta2GPI to AnPLs was enhanced by biotinylation of its glycan chains with biotin-hydrazide. In the present study, we investigated why this chemical modification of beta2GPI increased both its affinity for AnPLs and its recognition by anti-cardiolipin antibodies. Electrophoretic analysis showed that: (i) high molecular mass beta2GPI (dimers and other oligomers) covalently coupled by imine bonds, were present in variable amounts in oxidized beta2GPI and in beta2GPI-bh (beta2GPI-biotin-hydrazide), but were absent in native beta2GPI; (ii) binding of beta2GPI-bh to phosphatidylserine-coated microtitre plates generated high molecular mass polymers in a time-dependent manner. Native beta2GPI did not polymerize in these conditions. These polymers did not bind more strongly to AnPLs than the monomer beta2GPI. However, in solution at 1 microM beta2GPI-bh essentially appeared as a dimer as revealed by light-scattering analysis. SPR (surface plasmon resonance) analysis showed that the increased affinity of beta2GPI-bh for AnPL monolayers was due to a lower dissociation rate constant compared with native beta2GPI. Finally, the monoclonal human aCL (auto-immune anti-cardiolipin antibody) EY2C9 bound to beta2GPI-bh but did not bind to monomeric native and oxidized beta2GPI. It is likely that the dimeric quaternary structure of beta2GPI-bh is in fact responsible for the appearance of the epitopes targeted by the EY2C9 antibody.

Dokdonella koreensis gen. nov., sp. nov., isolated from soil

Two Gram-negative, motile, non-spore-forming and rod-shaped bacterial strains, DS-123T and DS-140, were isolated from soil and their taxonomic positions were investigated by a polyphasic study. Strains DS-123T and DS-140 grew optimally at 30 degrees C and pH 6.5 without NaCl. They contained Q-8 as the predominant ubiquione and iso-C(17 : 1)omega9c, iso-C(17 : 0) and iso-C(15 : 0) as the major fatty acids. Major polar lipids detected in the two strains were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an amino-group-containing lipid that was ninhydrin-positive. Their DNA G+C contents were 71.0 mol%. Strains DS-123T and DS-140 exhibited no difference in their 16S rRNA gene sequences and possessed a mean DNA-DNA relatedness level of 92 %. Phylogenetic trees based on 16S rRNA gene sequences showed that strains DS-123T and DS-140 formed a distinct evolutionary lineage within the Gammaproteobacteria. The 16S rRNA gene sequences of strains DS-123T and DS-140 exhibited similarity values of less than 94.1 % to members of the Gammaproteobacteria. Strains DS-123T and DS-140 were distinguished from phylogenetically related genera by differences in some phenotypic properties. On the basis of phenotypic, phylogenetic and genetic data, it is proposed that strains DS-123T (= KCTC 12396T = DSM 17203T) and DS-140 be classified in a novel genus and species, Dokdonella koreensis gen. nov., sp. nov.

[Effect of TFX preparation on the course of pregnancy in rabbits with experimental antiphospholipid syndrome]

Recurrent thrombo-embolic episodes and pregnancy loss, thrombocytopenia and the presence of antiphospholipid antibodies, first described in 1983 by Hughes and defined by Harris in 1987, are characteristic of the primary antiphospholipid syndrome (APS). APS is the cause of obstetrical problems in the form of recurrent miscarriages, intrauterine fetal death or growth retardation, and EPH gestosis. Clinical symptoms described above are probably mediated by antiphospholipid antibodies which interact with endothelial and trophoblastic cells, blood platelets, embryonic tissue cells, as well as with coagulation factors and proteins involved in the coagulation cascade or in antibody binding. Management of APS includes antiaggregation, anticoagulation, immunosuppression, and intravenous administration of gamma globulins. Successful treatment is not always the case and search for more efficient therapies continues. The importance of animal experiments led to the design at the Department of Pathology of Pregnancy and Labour of an APS model in pregnant and nonpregnant rabbits. As Turowski et al. have confirmed the immunomodulating action of TFX in rabbits, it seemed justified to examine the properties of this preparation in pregnant rabbits with experimentally induced APS. The material consisted of 30 pregnant New Zealand rabbits, divided into the following groups: I--10 pregnant rabbits (and 63 fetuses) treated intradermally twice weekly since the 10th day of pregnancy with cardiolipin together with adjuvant; I-K--5 pregnant rabbits (and 17 fetuses) treated with cardiolipin and adjuvant in the same manner as group I and additionally with intramuscular injections of 0.9% NaCl on the 20th, 21st, and 22nd day; I-T--10 pregnant rabbits (and 66 fetuses) treated with cardiolipin with adjuvant in the same manner as group I and additionally with intramuscular injections of 10 mg/day of TFX (Jelfa, Poland) on the 20th, 21st, and 22nd day of pregnancy; K--5 pregnant rabbits (and 27 fetuses) treated with injections of 0.9% NaCl twice weekly. Blood samples for laboratory analysis were collected by cardiac puncture before immunization (sample I) and on the day of caesarean section (sample II). Platelet counts and APTT tests were done. Numbers of live and dead newborns, resorbed fetuses, body mass, newborn viability and survival rates were recorded. TFX administered to pregnant rabbits with experimentally induced antiphospholipid syndrome increased the number of live newborns, reduced the incidence of fetal resorption, increased the viability and survival rate of newborn rabbits. The beneficial effect of TFX on APTT and platelet count was revealed, such that these parameters remained within the normal range despite immunization. Morphological changes observed in the placenta were not specific.

Determination of electrophoretic mobility distributions through the analysis of individual mitochondrial events by capillary electrophoresis with laser-induced fluorescence detection

Here we report on the analysis of mitochondrial preparations by capillary electrophoresis with postcolumn laser-induced fluorescence detection. Individual mitochondria are detected by fluorescent labeling with the mitochondrion-selective probe, 10-nonyl acridine orange. Interactions between the organelles and the capillary walls are controlled by derivatization of the capillaries with poly(acryloylaminopropanol). As expected from the presence of charged groups in their outer membranes, isolated mitochondria have intrinsic electrophoretic mobilities. This property may be influenced by variations in size, morphology, membrane composition, and damage caused during the isolation procedure. The mobility distributions of mitochondria isolated from NS1 and CHO cells ranged from -1.2 x 10(-4) to -4.3 x 10(-4) cm2 V(-1) s(-1) and -0.8 x 10(-4) to -4.2 x 10(-4) cm2 V(-1) s(-1), respectively. Furthermore, there seems to be no correlation between the density of the mitochondrial fraction and the resultant electrophoretic mobility distribution. These results suggest a new method for characterization of organelle fractions and for counting individual organelles.

[Use of magnetosorbents in the immunodiagnosis and therapy of systemic lupus erythematosus and rheumatoid arthritis]

The authors present new technology of producing immobilized granulated antigenic magnetosorbents (MS) using collagen type II, IgG, denaturated DNA and cardiolipin which were employed in enzyme immunoassay for detection of specific antibodies in the blood of patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Due to high capacity, MS demonstrated effectiveness in early diagnosis, prognosis of RA and SLE as well as in control over the treatment effects. As shown in in vitro experiments, MS have high selective capacity and atraumaticity for blood corpuscles. MS can be sterilized, regenerated and reused which is a great advantage.

Interferometric fringe fluorescence photobleaching recovery interrogates entire cell surfaces

Fluorescence photobleaching recovery (FPR) measurements of cell surface protein lateral diffusion typically employ an interrogated spot of 0.5 microm 1/e2 radius. The effective spot area represents only 1/500 of the total surface of an 8-microm cell. An FPR measurement of a protein expressed as 50,000 copies per cell reflects the dynamics of 100 molecules. This limits the precision and reproducibility of FPR measurements. We describe a method for interferometric fringe pattern FPR that permits simultaneous interrogation of the entire cell's surface. Fringe patterns are generated interferometrically within the optical path of an FPR system. Methods for interpreting fluorescence recovery kinetics on cells and for determining the protein mobile fraction are presented. With fringe FPR, the murine major histocompatibility complex class II antigen I-Ak expressed on M12.C3.F6 cells has 100-fold improved fluorescence signals relative to spot FPR, with corresponding improvements in signal-to-noise ratios of recovery traces. Diffusion coefficients (+/- standard deviation) of (2.1 +/- 0.4) x 10(-10) and (1.8 +/- 1.0) x 10(-10) cm2 s-1 with corresponding mobile fractions of I-Ak of 66.1 +/- 7.8% and 63.4 +/- 18.0% were obtained by fringe and spot methods, respectively. The improved reproducibility of fringe over spot results is less than signal improvements predict. There may thus be substantial variation from cell to cell in protein dynamics, and this method may permit the assessment of such variation.

Reconstituted adenine nucleotide translocase forms a channel for small molecules comparable to the mitochondrial permeability transition pore

Highly purified adenylate translocase (ANT) from rat heart mitochondria was functionally reconstituted as ATP/ADP exchange carrier in asolectin/cardiolipin vesicles. The ANT preparations used were free of porin, cyclophilin D, and Bax as analysed immunologically and by activity measurements. After pre-loading the ANT-containing proteoliposomes with ATP, malate or AMP, a gradual release of the trapped compounds by increasing the external Ca2+ concentrations could be demonstrated. N-Methyl-Val-4-cyclosporin did not inhibit the Ca2+ dependent release of internal substances from ANT liposomes. This inhibitor was found to be specific for the mitochondrial permeability transition pore (MTP) in intact mitochondria or reconstituted MTP-like protein complexes (e.g. hexokinase, porin, ANT complex). However, ADP in concentrations > 20 microM inhibited the liberation of internal compounds, while in contrast, atractyloside (30 microM) and HgCl2 (5 microM) both induced permeability of the ANT-containing liposomes resulting in a release of trapped substances. These results strongly suggest that ANT itself is capable to adopt a pore-like structure under conditions known to induce the permeability transition in mitochondria.

Evidence that nonbilayer phase propensity of the membrane is important for the side chain cleavage activity of cytochrome P450SCC

To analyze whether specific protein-lipid interactions or physical features of the membrane contribute to cytochrome P450SCC (CYP11A1) activation by lipids, dimyristoylphosphatidylcholine/cardiolipin and dimyristoylphosphatidylcholine/branched phosphatidylcholine vesicles of defined acyl chain structure were studied for their ability to stimulate the side chain cleavage activity of the enzyme. Activation was found to increase with the mole percent of nonbilayer lipids in the system and the chain lengths of both the branched and main fatty acyl chains of the activator lipid. Unsaturation provided by dioleoylphosphatidylcholine as host lipid leads to a further increase in the potency of the branched phosphatidylcholines to activate the enzyme. The observed activation can be qualitatively interpreted in terms of the effect of these lipids on the hydrophobic volume of the membrane. Using differential scanning calorimetry, we showed that the branched phosphatidylcholines perturb the bilayer membrane structure of dimyristoylphosphatidylcholine and lower the bilayer to hexagonal phase transition temperature of dielaidoylphosphatidylethanolamine, i.e., promote hexagonal phase formation. We also examined the effect of eicosane on both the cytochrome P450SCC activity and the lipid polymorphism and found that eicosane increases both the activity and the hexagonal phase propensity of the vesicle membrane. Because of these correlations, we conclude that the nonbilayer phase propensity of the membrane rather than specific binding of activator lipids to the enzyme explains best the observed activation of enzymatic activity by the lipids.

Outer leaflet-packing defects promote poly(ethylene glycol)-mediated fusion of large unilamellar vesicles

Poly(ethylene glycol)-induced fusion of two different vesicle systems has been examined: dipalmitoylphosphatidylcholine (DPPC) large unilamellar vesicles (LUV) and cardiolipin (CL)/dioleoylphosphatidylcholine (DOPC) (1:10) LUVs. A slight perturbation was established in the outer leaflets of DPPC LUVs by hydrolyzing 0.8% of the outer leaflet lipid with phospholipase A2 to produce lysophosphatidylcholine and palmitate which were then removed by bovine serum albumin. Similarly, 5 mM Ca2+ was added to the external compartment of CL/DOPC LUVs to alter the shape of the CL molecule and thereby create a perturbation in the outer leaflet packing of these vesicles. Contents mixing assays showed that both vesicle systems fused only when the outer leaflets of both contacting vesicles were perturbed as described. Two fluorescent probes (C6-NBD-PC and TMA-DPH) were used to detect changes in outer leaflet molecular packing between nonfusing and fusing systems. The steady-state fluorescence intensity of C6-NBD-PC added externally to either fusing system was enhanced relative to that of nonfusing vesicles. Phase-resolved measurements of probe lifetime showed that this was due mainly to enhanced partitioning of probe from a micellar state into fusing versus nonfusing membranes. Similarly, TMA-DPH was found to undergo more rapid motion when incorporated into fusing as opposed to nonfusing vesicles. The effects of deuterium exchange on probe lifetime also indicated that C6-NBD-PC and TMA-DPH penetrated more deeply into fusing than into nonfusing membranes. These results suggest that the fusogenic perturbations produced in these two very different lipid systems took the form of altered outer leaflet packing. We conclude that, for the two model lipid bilayers examined, small perturbations in lipid packing within contacting bilayer leaflets are necessary and probably sufficient to promote membrane fusion.

Finding neurosyphilis without the Venereal Disease Research Laboratory test

BACKGROUND

The cerebrospinal fluid (CSF)-Venereal Disease Research Laboratory (VDRL) test is only 27% sensitive for diagnosing neurosyphilis. Discriminant analysis, used on 124 patients, shows that other commonly used laboratory tests can, in combination, identify 87% of patients with neurosyphilis with 94% specificity.

STUDY DESIGN

The insensitivity of the CSF-VDRL (27% in persons with neurosyphilis) and the foreseen greater need to identify and treat neurosyphilis in the era of human immunodeficiency virus caused us to analyze the serum and cerebrospinal fluid results of 73 patients with syphilis and of 51 patients with clinically diagnosed neurosyphilis. Discriminant analysis was applied to different sets of laboratory tests to find the combination of test results best able to predict retrospectively the clinical diagnosis of syphilis or neurosyphilis, without reference to the CSF-VDRL.

RESULTS

The predicting function averages 94% specificity and 87% sensitivity. Test result variables considered together are: CSF-FTA-ABS, serum FTA-ABS, CSF-TPHA, serum TPHA, and CSF cells.

CONCLUSIONS

The authors conclude that clinicians or laboratories can, independently of the CSF-VDRL, compute a score showing whether the results of a set of commonly used tests suggest neurosyphilis in a patient.

Quinine induced lupus-like syndrome and cardiolipin antibodies

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Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. I. Binding of cytochrome c to cardiolipin/phosphatidylcholine membranes in the absence of oxidase

The mechanism of interaction between cytochrome c and a solid-supported planar phosphatidylcholine membrane containing varying amounts of cardiolipin (0-20 mol%) has been studied over a wide range of protein concentrations (0-450 microM) and ionic strength conditions (10-150 mM), by direct measurement of protein binding using surface plasmon resonance (SPR) spectroscopy. The results demonstrate that cytochrome c binds to such phospholipid membranes in two distinct phases characterized by very different (approximately one order of magnitude) affinity constants. The second phase is dependent upon the prior occurrence of the first binding process. Although the binding affinities for both modes of binding are highly sensitive to both the cardiolipin concentration and the ionic strength of the buffer solution, indicating that electrostatic forces are involved in these processes, binding cannot be reversed by salt addition or by dilution. Furthermore, the final saturation levels of adsorbed protein are independent of ionic strength and cardiolipin concentration. These observations suggest that binding involves more than a simple electrostatic interaction. Invariance in the shapes of the SPR spectra indicates that no major structural transitions occur in the proteolipid membrane due to cytochrome c binding, i.e., the bilayer character of the lipid phase appears to be preserved during these interactions. Based on these results, a model of the lipid membrane-cytochrome c interaction is proposed that involves varying degrees of protein unfolding and subsequent binding to the membrane interior via hydrophobic forces.

Surface plasmon resonance studies of complex formation between cytochrome c and bovine cytochrome c oxidase incorporated into a supported planar lipid bilayer. II. Binding of cytochrome c to oxidase-containing cardiolipin/phosphatidylcholine membranes

Complex formation between horse heart cytochrome c (cyt c) and bovine cytochrome c oxidase (cco) incorporated into a supported planar egg phosphatidylcholine membrane containing varying amounts of cardiolipin (CL) (0-20 mol%) has been studied under low (10 mM) and medium (160 mM) ionic strength conditions by surface plasmon resonance (SPR) spectroscopy. Both specific and nonspecific modes of cyt c binding are observed. The dissociation constant of the specific interaction between cyt c and cco increases from approximately 6.5 microM at low ionic strength to 18 microM at medium ionic strength, whereas the final saturation level of bound protein is independent of salt concentration and corresponds to approximately 53% of the total cco molecules present in the membrane. This suggests a 1:1 binding stoichiometry between the two proteins. The nonspecific binding component is governed by electrostatic interactions between cyt c and the membrane lipids and results in a partially ionic strength-reversible protein-membrane association. Thus, hydrophobic interactions between cyt c and the membrane, which are the predominant mode of binding in the absence of cco, are greatly suppressed. Both the amount of nonspecifically bound protein and the binding affinity can be varied over a broad range by changing the ionic strength and the extent of CL incorporation into the membrane. Under conditions approximating the physiological state in the mitochondrion (i.e., 20 mol% CL and medium ionic strength), 1-1.5 cyt c molecules are bound to the lipid phase per molecule of cco, with a dissociation constant of 0.1 microM. The possible physiological significance of these observations is discussed.

Modern diagnosis and management of acquired syphilis

Syphilis presents to clinicians in a wide range of disciplines and requires a high index of suspicion. This article summarizes the interpretation of syphilis serology and provides practical guidelines for the management of acquired syphilis in liaison with local genitourinary medicine physicians.

The major carotenoid pigment of a psychrotrophic Micrococcus roseus strain: fluorescence properties of the pigment and its binding to membranes

The fluorescence excitation and emission spectra are reported for P-3 (bis-dehydro-B-carotene-2-carboxylic acid), the major carotenoid pigment of psychrotrophic M. roseus. The excitation spectrum and the absorption spectrum showed good agreement with respect to the position of their peak maxima. The study also demonstrates that P-3 binds to liposomes prepared from synthetic lipids (PC, DOPG, or CL) or the total lipids of a mutant colourless M. roseus. Binding of P-3 to the membranes was accompanied by a decrease in the fluorescence emission intensity and a blue shift in lambda(em) maximum by 15 to 20 nm. The quantum yield of P-3 was observed to be low (1.7 x 10(-5)).