Glycosphingolipid acyl chain orientational order in unsaturated phosphatidylcholine bilayers

The glycosphingolipid, galactosyl ceramide (GalCer), was studied by 2H nuclear magnetic resonance (NMR) in fluid phospholipid bilayer membranes, with regard to arrangement of its acyl chain. For this purpose, species with perdeuterated 18-carbon fatty acid (18:0[d35]GalCer) or with perdeuterated 24-carbon fatty acid (24:0[d47] GalCer) were dispersed in bilayers of the 18-carbon phospholipid, 1-stearoyl-2-oleoyl-phosphatidylcholine (SOPC). For 18:0[d35] GalCer, smoothed profiles of the order parameter, SCD, were found to be very similar to one another over the range of glycolipid concentration, 5-40 mol%. In addition, they were very similar to orientational order parameter profiles well known from the literature on phospholipid and glycolipid acyl chains (which deals in general with membranes of homogeneous chain length in the range 14-18 carbons). Corresponding order parameter profiles for the long-chain species, 24:0[d47] GalCer, were also similar to one another for glycolipid concentrations between 5 and 40 mol%. Their shapes, however, were distinctly different from those of the shorter chain analogues. SCD profiles for the two species were quantitatively similar to a membrane depth of C15. SCD values at C16 and C17 were approximately 20 and 30%, respectively, higher for the long-chain glycosphingolipid than for its short-chain analogue in SOPC. Nitroxide spin labels attached rigidly to C16 of the long-chain glycolipid in SOPC gave electron paramagnetic resonance (EPR) order parameters that were twice as high as for a spin label at C16 on the shorter chain glycolipid. Comparison was made between spectra of 24:0[d47] GalCer in SOPC and fully hydrated bilayers of the pure 24:0[d47] GalCer, a system that is considered to be partially interdigitated in fluid and gel phases. The resultant 2H NMR order parameter profiles displayed similar features, indicating that related organizational properties exist in these fluid systems. Effective chain length of 24:0[d47] GalCer within the SOPC membrane was calculated using the method of Schindler and Seelig (1975. Biochemistry, 14:2283-2287). The result suggested that the long-chain fatty acid should protrude roughly one third of the host matrix chain length across the bilayer midplane. However, a treatment of the same order parameters making very few assumptions about chain conformation indicated a high degree of orientational flexibility for the "extra" length of the long chain fatty acid. It seems likely that a realistic treatment of the long-chain fatty acidin a shorter chain fluid host matrix considers interdigitation as a subset of the conformational possibilities, many of which are rapidly interconverting on the NMR timescale of 10-4_10-5 s and longer lived on the EPR timescale of 10-8_10-9 s.

Molecular adaptation of vascular endothelial cells to oxidative stress

Cellular organisms respond at the cellular and molecular level when confronted with sudden changes in environment, and molecular adaptation represents the ability of the cells to acclimate themselves to their new environment. In this study we examined the response of bovine vascular endothelial cells (VEC) to the oxidative stress by exposing the cultured cells to two different concentrations of H2O2, 0.04 or 0.08 mM, for 18-24 h. H2O2-exposed VEC displayed good viability (85-90% for 0.04 mM H2O2; 75-80% for 0.08 mM H2O2) and exhibited normal morphology. H2O2 treatment of the VEC was associated with the expression of a number of new proteins, as demonstrated by two-dimensional gel electrophoresis of total cell lysate. Cells exposed to 0.04 mM H2O2 expressed 25 new proteins, whereas 19 newly expressed proteins were detected when the cells were exposed to 0.08 mM H2O2. Western blot analysis of H2O2-treated VEC using specific antibodies to heat-shock proteins (HSP) identified one of these proteins as a member of the HSP 70 family. In addition, H2O2 induced an increase in antioxidative enzyme activities in the VEC, including superoxide dismutase, catalase, and glutathione peroxidase. Moreover, these changes were a truly adaptive phenomenon because challenging the VEC with brief exposure to toxic levels of H2O2 (1 mM for 30 min) showed increased viability (by Trypan blue exclusion test) and decreased injury (by lactate dehydrogenase supernatant-to-cellular ratio determination) in adapted cells (preexposed to 0.04 or 0.08 mM H2O2) compared with control cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of glycosphingolipid fatty acid chain length on behavior in unsaturated phosphatidylcholine bilayers: a 2H NMR study

Deuterium-labeled glycosphingolipids, N-lignoceroyl[d47]galactosylceramide (24:0 fatty acid form) and N-stearoyl[d35]galactosylceramide (18:0 fatty acid form) were prepared by partial synthesis. These probe-labeled species, differing only in the lengths of their fatty acids, were compared via 2H NMR with regard to arrangement and behavior in bilayers of the monounsaturated phospholipid 1-stearoyl-2-oleoylphosphatidylcholine (SOPC). Results were used to consider the physical significance of the great range of common acyl chain lengths that is a frequent feature of cell membrane glycosphingolipids. N-lignoceroyl[d47]- and N-stearoyl[d35]galactosylceramide were incorporated at concentrations ranging from 5 to 50 mol % into unsonicated phospholipid liposomes, and their spectra were analyzed in the range +73 to -14 degrees C. For the 18:0 fatty acid derivative, first spectral moments, M1, were calculated and plotted as a function of temperature for each sample composition. Spectral inspection for regions of phase coexistence, in conjunction with consideration of M1 curves, permitted derivation of phase diagram boundaries which were then refined using spectral subtraction techniques. The phase diagram for galactosylceramide with short fatty acid in SOPC was compared to the corresponding phase diagram for its long-chain analogue, derived previously in the same fashion [Morrow, M. R., Singh, D., Lu, D., & Grant, C. W. M. (1992) Biochim. Biophys. Acta 1106, 85-93]. The binary phase diagrams referred to above, which reflect the behavior of short- and long-chain glycolipids in a common phospholipid host matrix, displayed important similarities and differences. In fluid membranes, the behavior appeared to be remarkably alike, as reflected in superimposable fluidus curves over the concentration range studied.(ABSTRACT TRUNCATED AT 250 WORDS)

BCR-ABL tyrosine kinase is autophosphorylated or transphosphorylates P160 BCR on tyrosine predominantly within the first BCR exon

The role of BCR gene sequences in Philadelphia (Ph) chromosome-positive leukemia is not well understood. Our previous studies demonstrated that P210 BCR-ABL co-precipitates with P160 BCR following immunoprecipitation with antibodies to the C-terminal domain of P160 BCR, sequences lacking in P210 BCR-ABL. We now report that tryptic peptides shared by both P160 BCR and P210 BCR-ABL are phosphorylated on tyrosine in vitro either when using immune complexes containing P160 BCR complexed to BCR-ABL or when P160 BCR is phosphorylated in trans by P210 BCR-ABL immune complexes from cells lacking functional P160 BCR. P185 BCR-ABL produced in a cell line derived from a Ph chromosome-positive acute lymphocytic leukemia patient also co-immunoprecipitated with P160 BCR. As with P210 BCR-ABL, P160 BCR tyrosine phosphopeptides were shared with P185 BCR-ABL, indicating that the major sites of tyrosine phosphorylation in vitro are contained within the first exon of P160 BCR. Similarly, BCR-ABL autophosphorylation was found to occur predominantly at tyrosines within BCR exon 1 sequences. These results raise the possibility that the activated ABL protein kinase of BCR-ABL proteins modulates the putative signal transduction activities of P160 BCR by tyrosine phosphorylation of exon 1 sequences.

[The clinical relevant factors of the myocardial ischemic threshold]

The myocardial ischemic threshold (heart rate at the onset of ischemia) was assessed in 92 patients with coronary heart disease. The highest myocardial ischemic threshold (HMIT) ranged from 83 to 163 (122 +/- 18) beats/min usually happened during activities at the daytime. The lowest myocardial ischemic threshold (LMIT) ranged from 45 to 115 (82 +/- 17) beats/min usually happened when awaken early morning or asleep at night. The differences were statistically significant (P < 0.01). The mean variability of myocardial ischemic threshold (VMIT) was 30.22% (range from 8.2 to 51.2%). The variability was correlated positively with the number of ischemic episodes, negatively with LMIT, and larger in senior-aged group than in middle-aged group (P < 0.001). The authors suggest that LMIT and VMIT may be related to the severity of coronary lesions, coronary tonus, and the patients' prognosis, etc.

Angiotensin-II induction of plasminogen activator inhibitor-1 gene expression in astroglial cells of normotensive and spontaneously hypertensive rat brain

Angiotensin-II (AII) stimulates plasminogen activator inhibitor-1 (PAI-1) gene transcription, translation, and protein secretion from astroglial cells derived from normotensive [Wistar-Kyoto (WKY)] rat brain, an effect mediated by AII type 1 (AT1) receptors. Since abnormal expression of the brain AII system has been demonstrated in spontaneously hypertensive (SH) rats, we investigated the regulation of PAI-1 gene expression by AII in astroglial cells from the brains of these animals. AII caused an increase in PAI-1 gene expression in SH rat astroglia in a manner similar to that observed in WKY-derived cultures. However, both the basal and AII-stimulated levels of PAI-1 mRNA in SH rat astroglia were only 20% of those observed in WKY rat astroglial cultures. Consequently, there was a significant reduction in the de novo synthesis and secretion of PAI-1 from astroglia of SH rat brain. The reduced synthesis and secretion of PAI-1 from SH rat brain astroglia was associated with lower numbers of AT1 receptors in these cells. However, the steady state levels of AT1 receptor mRNA were comparable in both WKY and SH rat astroglia. This reduction in AII-modulated PAI-1 levels in SH rat astroglia is consistent with a proposed role of these interactions in the development of hypertension in these animals.

Preconditioning of heart by repeated stunning. Adaptive modification of antioxidative defense system

Previous studies demonstrated that preconditioning of a heart by repeated stunning can reduce the cellular injury to the heart from subsequent acute ischemic insult. To examine the possible biochemical mechanism for such myocardial preservation afforded by preconditioning, swine heart was subjected to four episodes of 5 min. stunning by occluding the left anterior descending coronary artery (LAD), followed by 10 min. of reperfusion after each stunning. Heart was then made regionally ischemic for 60 min. by LAD occlusion, followed by 6 hrs. reperfusion. Control heart was perfused for 60 min., followed by 60 min. ischemia and 6 hrs. reperfusion. The results of our studies indicated the stimulation of a number of antioxidative enzymes, including Mn-superoxide dismutase (Mn-SOD), catalase, glutathione peroxidase, and glutathione reductase, after repeated stunning and reperfusion. In addition, a number of new proteins were expressed after preconditioning the heart, including some oxidative-stress related proteins and 72 kDa heat-shock protein. These results suggest that preconditioning of a heart by repeated stunning may lead to strengthening of the oxidative defense system of the heart, which is likely to play a role in myocardial preservation during subsequent ischemic and reperfusion injury.

Specific chromosomal translocations and therapy-related leukemia induced by bimolane therapy for psoriasis

This paper reports for the first time results of cytogenetic studies on 14 consecutive secondary acute non-lymphocytic leukemia (S-ANLL) induced by bimolane therapy. They included 10 males and 4 females with ages ranging from 17 to 54 years. They had all suffered from psoriasis and received bimolane treatment before the occurrence of their leukemia. The total dose of bimolane ranged from 40 to 400 g (mean dose 194 g). The interval between the initiation of bimolane therapy and the diagnosis of leukemia was 12-96 months (median 30 months). A preleukemic phase was only found in one case. No dysplastic features in the hemopoietic series were seen in any patient. Chromosome analysis of bone marrow cells using banding techniques revealed clonal karyotypic abnormalities in all cases: t(15;17) in 8 cases of M3, of which 75% had extra abnormalities, t(8;21) in 4 cases of M2, del(7q) only in one case of M4 and one case of M5. After antileukemic therapy, complete remission was obtained in 10 out of 12 cases with specific translocations and one out of 2 cases with 7q-anomaly, respectively. The former survived 4-58 months (median 12 months), while the latter 1 and 9 months, respectively. This study indicates that: (1) bimolane is a causative factor of leukemia in this series; (2) the leukemia in our series is therapy-related leukemia (TRL) rather than de novo ANLL; (3) there exists, in fact, a new subgroup of TRL characterized by specific rearrangements, whose clinical, hematological and prognostic features and pathogenetic mechanism may be different from classical TRL characterized by chromosome abnormalities involving absence or deletion of parts of chromosome 5 and/or 7.

[Vibrio cholerae toxin B subunit gene expressed in a Salmonella vaccine strain]

This paper reports that the V. cholerae toxin B subunit (ctx B) gene was inserted into pYA 248 plasmid with the aspartate beta-semialdehyde dehydrogenase (asd)gene and the recombinant plasmid was transformed into S. typhimurium deleting asd gene. Results showed that ctx B gene was highly expressed and secreted into midium. This strain was able to colonize in the intestinal epithelium. Oral immunity and general immunity could produce antibodies at high level and enhance cellular immune responses. The animals orally inoculated with S. typhimurium x 4072 (pYA-ctx B) vaccine had remarkable protection against virulent V. cholear 569B strain and S. typhimurium strain. Use of such system provides useful method for oral vaccine.

Protection from cold injury by deferoxamine, an iron chelator

The presence of hydroxyl radical (OH) has been implicated in the pathogenesis of cold injury. Since iron is known to catalyze the OH formation responsible for cellular injury, this study was designed to examine whether an iron chelator such as deferoxamine can salvage a tissue from cold injury. Cold injury was induced in the hind limbs of rabbits. The experimental group received 0.6 mM of deferoxamine through the femoral vein prior to cooling of the limbs. Deferoxamine reduced the tissue injury, as evidenced by the decreased release of lactate dehydrogenase, a nonspecific marker for cellular injury. In addition, this drug inhibited OH formation and lipid peroxidation when examined by monitoring the formation of conjugated dienes and malonaldehyde, presumptive markers for lipid peroxidation. Rewarming of the cooled limbs was also associated with the loss of membrane phospholipids, with the corresponding accumulation of lysophosphoglycerides and free fatty acids, especially linoleic and arachidonic acids. Deferoxamine prevented the loss of phospholipids and inhibited the accumulation of amphipathic lipid products. These results indicates that deferoxamine salvaged the tissue from cold injury, possibly by preventing the formation of OH presumably by chelating iron, thus protecting the phospholipids from free radical attack.

A polymerase chain reaction assay for the detection and quantitation of cytokine gene expression in small numbers of cells

A reverse transcriptase-polymerase chain reaction (RT-PCR) assay is described that allows the rapid detection and quantitation of mRNA encoding the cytokines interleukin-2 (IL-2), IL-4 and interferon-gamma (IFN-gamma). Analysis of cytokine production by defined CD4+ T cell clones and the thymoma cell line EL4, demonstrates that the oligonucleotide primers used in this assay are specific for the genes encoding the individual cytokines, generating PCR products of different sizes. This allows the simultaneous and unambiguous detection of all three cytokine mRNAs in the same cDNA sample. The assay is sensitive enough to reproducibly detect cytokine mRNA expressed in as few as ten cells and requires 10,000-fold less cells for the detection of IL-2 production than that required for its detection using a conventional bioassay. Reverse transcribed mRNA is quantitated in the PCR assay by amplifying in the presence of a known amount of competitive genomic DNA (gDNA) template containing a small intron using the same primers. The PCR products obtained form the target cDNA and gDNA templates, which are distinguished by size, are processed by Southern analysis and quantitated by scanning densitometry of autoradiographs. As little as two-fold differences in cytokine mRNA can be reliably detected using this assay. We have demonstrated the successful application of this assay to the quantitation of pg amounts of IL-2 mRNA that is constitutively produced at low levels by fetal thymocytes in vivo during T cell ontogeny. The sensitivity, specificity, reliability and speed of this assay will facilitate the analysis of cytokine production in in vivo-derived or, in vitro propagated cells which are not available in sufficient numbers for analysis using more conventional molecular and biochemical assays.

Construction of a recombinant oral vaccine against Salmonella typhi and Salmonella typhimurium

The viaB gene coding for the Vi antigen of Salmonella typhi Ty2 was subcloned into expression vector pYA248. The recombinant plasmid was termed SMM202 and transformed into Salmonella typhimurium chi 4072, an attenuated delta cya delta crp mutant. Recombinant S. typimurium Vi4072 had the ability to produce Vi capsular polysaccharide and also to invade and colonize the small intestine, mesenteric lymph nodes, and spleen of BALB/c mice. Mice orally immunized with Vi4072 developed serum and secretory antibody responses to the Vi antigen, as measured by a passive hemagglutination assay. Mice developed a delayed-type hypersensitivity following a footpad injection with Vi antigen after being sensitized orally with a suitable dose of Vi4072. Immunization of mice with Vi4072 afforded complete protection against fatal infection with virulent S. typhi Ty2. All data indicate that this route of antigen delivery is effective for stimulating antibody-mediated immunity and for inducing a cell-mediated immune response in BALB/c mice. Thus, S. typhimurium Vi4072 may serve as a vaccine for protection against typhoid fever and salmonellosis caused by S. typhimurium.

Chain-length dependence of lipid bilayer properties near the liquid crystal to gel phase transition

The temperature dependence of the mean orientational order parameter in the vicinity of the liquid crystal to gel phase transition is obtained from the first moment M1 of deuterium nuclear magnetic resonance spectra for bilayers of chain perdeuterated phosphatidylcholines with acyl chains of 12, 14, 16, and 18 carbons. The data clearly show an increasing temperature dependence of the orientational order parameter in the vicinity of the transition, with the effect becoming more pronounced with decreasing chain length. Assuming a linear relationship between the mean orientational order parameter and the extension of the acyl chain, estimates of the change in area of the membrane at the transition are shown to be consistent with those obtained from other measurements. It is shown that the transition may be modeled in terms of a Landau expansion of the free energy involving a small number of phenomenological parameters. From this it is shown that the behavior of these systems in the temperature range of interest is, in large part, controlled by the close proximity of a spinodal to the transition temperature.

Monoclonal antibodies specific for mercuric ions

Monoclonal antibodies (mAbs) that react with soluble mercuric ions have been produced by injection of BALB/c mice with a hapten-carrier complex designed to maximize exposure of the metal to the immune system. Three hybridomas producing antibodies that reacted with bovine serum albumin (BSA)-glutathione-HgCl, but not with BSA-glutathione, were isolated from the spleen of a mouse given multiple injections with glutathione-HgCl conjugated to keyhole limpet hemocyanin. Stable subclones were established from two of these antibodies, designated mAb 4A10 and mAb 1F10. The binding of both antibodies to immobilized BSA-glutathione-HgCl was inhibited by soluble HgCl2, and dissociation constants for mercuric chloride binding were 2.3 and 3.7 nM for mAbs 4A10 and 1F10, respectively. Both antibodies bound mercuric acetate with similar affinities, demonstrating that the antibodies were capable of binding to mercuric ions in the presence of a different counterion than the one used in the immunogen. Reactions were not observed with other metal cations by either antibody. These data demonstrate the successful induction of antibodies that react very specifically with mercuric ions in solution regardless of the presence of a carrier.

Glycosphingolipid phase behaviour in unsaturated phosphatidylcholine bilayers: a 2H-NMR study

2H-NMR was employed to consider the arrangement of a glycosphingolipid, N-(lignoceroyl-d47)galactosylceramide, in bilayers of the mono-unsaturated phospholipid, 1-stearoyl-2-oleoylphosphatidylcholine. The deuterated glycolipid prepared by partial synthesis was incorporated at concentrations ranging from 5 mol% to 53 mol% into unsonicated liposomes, and its spectra were recorded from +76 degrees C to -10 degrees C. First spectral moments were plotted as a function of temperature for each sample composition and, along with inspection of the spectra, were employed to infer a phase diagram describing glycolipid behaviour in the unsaturated phospholipid host matrix. It was possible to refine the result using 2H-NMR difference spectroscopy. The phase diagram obtained was indicative of peritectic behaviour. At glycolipid concentrations exceeding about 20 mol% there was considerable tendency to glycolipid phase separation--as indicated by coexistence of fluid phospholipid-enriched and gel phase glycolipid-enriched domains over a wide range of temperatures, and by coexistence of distinct ordered phase domains at lower temperature. In contrast, at lower glycolipid concentrations reflective of many biological membranes, the lipid components were miscible in both the liquid crystal and gel phases, with only a narrow temperature range of fluid and ordered phase coexistence. For the fluid phase at low glycolipid concentrations, spectra of the deuterated glycolipid 24-carbon fatty acid suggest that orientational order is low for a number of methylene groups near the methyl end of the chain.

Cloning, expression and localization of an RNA helicase gene from a human lymphoid cell line with chromosomal breakpoint 11q23.3

A gene encoding a putative human RNA helicase, p54, has been cloned and mapped to the band q23.3 of chromosome 11. The predicted amino acid sequence shares a striking homology (75% identical) with the female germline-specific RNA helicase ME31B gene of Drosophila. Unlike ME31B, however, the new gene expresses an abundant transcript in a large number of adult tissues and its 5' non-coding region was found split in a t(11;14)(q23.3;q32.3) cell line from a diffuse large B-cell lymphoma.

Characterization of a polyclonal anti-peptide antibody to the angiotensin II type-1 (AT1) receptor

A polyclonal antibody has been prepared against a synthetic peptide corresponding to amino acids 14-23 of the angiotensin II type-1 (AT1) receptor. The antibody is of high titer and mono-specific. Western blot analysis of membranes from rat liver, kidney, and adrenal gland showed that the antibody specifically recognizes a protein band of MW 70,000 whose amounts are highest in the liver, followed by kidney and adrenals. In addition, a relatively less prominent band of MW 95,000 was also detected. The relative distribution of this protein correlates well with the values obtained for [3H]-DuP753 binding and AT1 receptor mRNA.

[Chemical constituents of Rhodiola kirilowii (Reg.) Reg]

Three compounds were isolated from the water-soluble part of alcohol extracts of rhizomes of Rhodiola kirilowii. Two of them were identified as salidroside and tyrosol, respectively by chemical and spectral analysis. beta-sitosterol was obtained from the petroleum extracts of the plant.

Differential effect of interleukin 1 on naive and memory CD4+ T cells

Freshly derived murine CD4+ T cells are divided into naive and memory cells based on the expression of CD45 isoforms. Cross-linking the T cell receptor CD3 complex either by plastic-bound anti-CD3 antibodies or the antibody presented on non-lymphoid Fc gamma receptor type II-positive Chinese hamster ovary cells in absence of competent antigen-presenting cells fails to activate naive cells to either secrete cytokines or to proliferate. In contrast, memory cells secrete their characteristic cytokines [interleukin (IL) 2, IL4, and interferon-gamma] and show significant proliferation to this stimulus. IL 1 however, is required for their optimal clonal expansion. Differential expression of IL 1 receptor mRNA in memory cells also correlate with their responsiveness to IL 1. Thus, these data reveal a basic difference in the requirements for activation of naive and memory CD4+ T cells.

Alterations at the rel locus in human lymphoma

The rel proto-oncogene has been mapped to chromosome region 2p11.2-14, a site associated with nonrandom rearrangements in non-Hodgkin's lymphoma. We have characterized an abnormal rel mRNA from a cell line derived from a diffuse large cell lymphoma, in which the evolutionarily conserved N-terminal half of the rel coding region was fused with the C-terminal coding region of an unrelated gene. In addition, rearrangement or amplification of the rel locus was found in the lymphomatous tissue of two follicular and one diffuse large cell lymphoma. The findings suggest involvement of rel in the pathogenesis of large cell lymphoma.

Protection from nonfreezing cold injury by quinacrine, a phospholipase inhibitor

A recent study from our laboratory indicated additional tissue injury during rewarming of a cooled rabbit leg. Oxygen-derived free radicals were believed to play a role in such "rewarming injury." Since free radicals may attack membrane phospholipids, we analyzed the phospholipid composition in the leg tissue during cooling and rewarming. Our results indicated significant breakdown of membrane phospholipids, particularly phosphatidylcholine and phosphatidylethanolamine, with a corresponding accumulation of lysophosphatidylcholine and nonesterified fatty acids. Quinacrine, a phospholipase inhibitor, was able to preserve membrane phospholipids during rewarming of the cooled leg. Rewarming of cooled tissue was also accompanied by additional tissue injury, as evidenced by the increased release of lactic acid dehydrogenase and creatine kinase, as well as enhanced lipid peroxidation, as evidenced by increased malonaldehyde formation. Quinacrine reduced the release of these intracellular enzymes and decreased lipid peroxidation, suggesting its efficacy as a therapeutic agent against hypothermic injury.