Structural analysis of the lipopolysaccharide from Chlamydia trachomatis serotype L2

The lipopolysaccharide (LPS) of Chlamydia trachomatis L2 was isolated from tissue culture-grown elementary bodies using a modified phenol/water procedure followed by extraction with phenol/chloroform/light petroleum. From a total of 5 x 10(4) cm2 of infected monolayers, 22.3 mg of LPS were obtained. Compositional analysis indicated the presence of 3-deoxy-D-manno-oct-2-ulopyranosonic acid (Kdo), GlcN, phosphorus, and fatty acids in a molar ratio of 2.8:2:2.1:4.5. Matrix-assisted laser-desorption ionization mass spectrometry performed on the de-O-acylated LPS gave a major molecular ion peak at m/z 1781.1 corresponding to a molecule of 3 Kdo, 2 GlcN, 2 phosphates, and two 3-hydroxyeicosanoic acid residues. The structure of deacylated LPS obtained after successive treatment with hydrazine and potassium hydroxide was determined by 600 MHz NMR spectroscopy as Kdoalpha2-->8Kdoalpha2-->4Kdoalpha2-->6D-GlcpNbeta1 -->6D-GlcpNalpha 1,4'-bisphosphate. These data, together with those published recently on the acylation pattern of chlamydial lipid A (Qureshi, N., Kaltashov, I., Walker, K., Doroshenko, V., Cotter, R. J., Takayama, K, Sievert, T. R., Rice, P. A., Lin, J.-S. L., and Golenbock, D. T. (1997) J. Biol. Chem. 272, 10594-10600) allow us to present for the first time the complete structure of a major molecular species of a chlamydial LPS.

The influence of unsaturation on the phase transition temperatures of a series of heteroacid phosphatidylcholines containing twenty-carbon chains

A series of heteroacid sn-1,2 diacyl phosphatidylcholines (PC) with twenty-carbon fatty acyl chains has been synthesized. Each PC contained eicosanoate (20:0) in the sn-1 position and one of a group of eicosaenoic acids with increasing numbers of cis double bonds in the sn-2 position. The double bonds were at positions delta 11 (20:1), delta 11,14 (20:2), delta 11,14,17 (20:3), or delta 5,8,11,14 (20:4). The disaturated PC containing two eicosanoate chains was also studied. Aqueous dispersions of these PC were analyzed by differential scanning calorimetry, and data for the gel to liquid-crystalline transitions (given as PC: Tc (degrees C), Tmax (degrees C), delta H (kcal/mol)) were as follows - 20:0-20:0 PC: 66.8, 68.4, 15; 20:0-20:1 PC: 19.8, 22.2, 8; 20:0-20:2 PC: -4.3, 1.8, 5; 20:0-20:3 PC: 1.2, 4.4, 7; 20:0-20:4 PC: -10.7, -6.8, 3. Double bonds in excess of two per chain did not substantially change the transition temperatures of these heteroacid PC. There was a small effect of the location of the multiple double bonds on the transition temperature. The data is consistent with the model that the transition temperatures are determined by a balance between a decrease in the packing density in the gel and a decrease in the rotational freedom of the chains in the liquid crystal, both caused by the double bonds ((1983) Biochemistry 22, 1466-1473).

Changes of the mucosal n3 and n6 fatty acid status occur early in the colorectal adenoma-carcinoma sequence

Despite data favouring a role of dietary fat in colonic carcinogenesis, no study has focused on tissue n3 and n6 fatty acid (FA) status in human colon adenoma-carcinoma sequence. Thus, FA profile was measured in plasma phospholipids of patients with colorectal cancer (n = 22), sporadic adenoma (n = 27), and normal colon (n = 12) (control group). Additionally, mucosal FAs were assessed in both diseased and normal mucosa of cancer (n = 15) and adenoma (n = 21) patients, and from normal mucosa of controls (n = 8). There were no differences in FA profile of both plasma phospholipids and normal mucosa, between adenoma and control patients. There were considerable differences, however, in FAs between diseased and paired normal mucosa of adenoma patients, with increases of linoleic (p = 0.02), dihomogammalinolenic (p = 0.014), and eicosapentaenoic (p = 0.012) acids, and decreases of alpha linolenic (p = 0.001) and arachidonic (p = 0.02) acids in diseased mucosa. A stepwise reduction of eicosapentaenoic acid concentrations in diseased mucosa from benign adenoma to the most advanced colon cancer was seen (p = 0.009). Cancer patients showed lower alpha linolenate (p = 0.002) and higher dihomogammalinolenate (p = 0.003) in diseased than in paired normal mucosa. In conclusion changes in tissue n3 and n6 FA status might participate in the early phases of the human colorectal carcinogenesis.

A systematic method for the sensitive and specific determination of hair lipids in combination with chromatography

A systematic method for the sensitive, precise and accurate determination of hair lipids, including trace amounts of intrinsic endogenous cholesterol (CH), ceramide/N-palmitoyl-DL-dihydrosphingosine (CER/PDS), cholesterol sulfate (CS) and chemically bound 18-methyl eicosanoic acid (18-MEA), has been developed in combination with TLC/FID (flame ionization detection), LC/MS and GC/MS. TLC/FID was used for the simultaneous determination of squalene (SQ), wax esters (WEs), triglycerides (TGs) and free fatty acids (FFAs). Optimal conditions for LC/MS to determine CS and 18-MEA were developed using selected ion monitoring (SIM) under the negative ion mode of electrospray ionization. An alternative procedure for the determination of 18-MEA was also established using commercially available heneicosanoic acid (HEA). In GC/MS, the optimal selection of ions for SIM of trimethylsilylated CH and CER/PDS, and the use of on-column injection has enabled their simultaneous detection. This newly developed method has been used to characterize the hair lipid composition from the proximal root end to the distal tip of chemically untreated hair fibers from two different females, and specific changes of hair lipids probably due to its origin and individuals have been demonstrated for the first time. This method may be useful for clarifying the important roles of intrinsic endogenous 18-MEA, CS, CH and CERs in the function of the cell membrane complex of hair fibers.

Quantitative determination of hydroxy fatty acids as an indicator of in vivo lipid peroxidation: gas chromatography-mass spectrometry methods

A new method has been developed for the quantitation of lipid peroxidation products by gas chromatography-mass spectrometry. An important advantage over existing gas chromatography-mass spectrometry methods is the elimination of autoxidation during sample preparation. The sensitivity is sufficient to permit measurement of lipid peroxidation products under normal physiological conditions on as little as 1 mg of tissue. Lipids from whole tissue samples or cell preparations are reduced by catalytic hydrogenation during extraction. The hydrogenation stabilizes the compounds by saturating the double bonds and reducing the hydroperoxides to hydroxy derivatives. The saturated lipids are then saponified and the resulting fatty acids are converted to pentafluorobenzyl esters. Hydroxy fatty acids are further converted to trimethylsilyl ether derivatives. Quantitation is accomplished by negative ion chemical ionization gas chromatography-mass spectrometry, using deuterated internal standards. Specific products from polyunsaturated fatty acids can be quantitated, and the method differentiates between products produced by free-radical and photooxidation mechanisms. Increased levels of lipid peroxidation products, above normal physiological levels, that result from prooxidant conditions, such as exposure of animals to carbon tetrachloride, can be measured.

Determination of eicosanoids, phospholipids and related compounds by thermospray liquid chromatography-mass spectrometry

Thermospray mass spectrometry has proven to be a useful technique for analyzing various biological compounds including eicosanoids and phospholipids. Molecular ions as well as fragment ions which reveal useful structural information are produced for underivatized eicosanoids and phospholipids using filament-off or filament-on thermospray mass spectrometry, respectively. In conjunction with on-line chromatographic separation, complex mixtures of biological samples can be rapidly analyzed with great reliability. Data will be presented concerning the analysis of prostaglandins, other eicosanoids and molecular species of phospholipids as well as the application of these methodologies to complex biological samples.

Rat neutrophil function, and leukotriene generation in essential fatty acid deficiency

Since the essential fatty acid linoleic acid is the precursor of arachidonic acid and thus of leukotrine B4 (LTB4), essential fatty acid deficiency (EFAD) may result in decreased synthesis of this stimulator of neutrophil granulocyte functions. Peritoneal and blood neutrophils from rats fed a diet with only 0.3% of energy requirements as linoleic acid and exhibiting biochemical evidence of EFAD showed substantial functional impairments compared to neutrophils from rats maintained on a diet with 3% of the energy requirement as linoleic acid. Oxidative burst activation (assessed by chemiluminescence), chemotaxis and aggregation were impaired upon stimulation with formylpeptides or the ionophore A23187. In contrast, these functions were intact on stimulation with exogenous LTB4. Chemiluminescence was slightly but not significantly enhanced in EFAD rat neutrophils compared to controls when stimulated with phorbol myristate acetate (PMA). There were no differences between EFAD and control peritoneal neutrophils in the number of f-met-leu-phe (fMLP) receptors, or in their affinity for the ligand, assessed with fML(3H)P. The fraction of responding cells also were similar, assessed with dichlorofluorescein diacetate fluorescence. Moreover, the endogeneous LTB4 production in response to A23187 or fMLP was decreased by 57.7% and 63.5%, respectively, in EFAD peritoneal neutrophils. Thus, EFAD was associated with reductions of LTB4 production and neutrophil responsiveness to A23187 and formylpeptides but not to LTB4 or PMA, which supports the hypothesis that endogeneous LTB4 may contribute to the activation of neutrophil functions involved in inflammation and host defense.

Habitual fish consumption does not prevent a decrease in LCPUFA status in pregnant women (the Seychelles Child Development Nutrition Study)

Information on the status of long-chain polyunsaturated fatty acids (LCPUFAs) in pregnancy and breast milk in very high fish-eating populations is limited. The aim of this study was to examine dietary intake and changes in fatty acid status in a population of pregnant women in the Republic of Seychelles. Serum docosahexaenoic acid (DHA) decreased significantly between 28-week gestation and delivery (n=196). DHA status did not correlate significantly with length of gestation and was not associated with self-reported fish intake, which was high at 527 g/week. In breast milk, the ratio of DHA to arachidonic acid (AA) was consistent with those observed in other high fish-eating populations. Overall the data suggest that high exposure to LCPUFAs from habitual fish consumption does not prevent the documented decrease in LCPUFA status in pregnancy that occurs as a result of foetal accretion in the third trimester of pregnancy.

Modulation of avian lung eicosanoids by dietary omega-3 fatty acids

This study was conducted to determine if dietary omega-3 polyunsaturated fatty acids could modulate lung eicosanoid production. Three groups of chickens were depleted of essential fatty acids by feeding diets containing 1% hydrogenated coconut oil from hatching to 8 wk, followed by repletion for 3 wk with diets containing soybean oil (SBO) and linseed oil (LSO) separately or in combination. The ratio of linoleic acid (18:2 omega 6) to linolenic acid (18:3 omega 3) was 7.48, 1.17 or 0.32, respectively, for diets containing 10% SBO, 5% SBO/5% LSO or 10% LSO. A 10% SBO diet fed for 11 wk served as the control. Production of prostaglandin F2 alpha, prostaglandin E, thromboxane B2 and 6-keto-prostaglandin F1 alpha by incubated lung was lower in birds fed linseed oil, with total prostanoid production being 95, 42 and 22% of control values for the three dietary treatments, respectively. The ratio of arachidonic acid (20:4 omega 6) to linoleic acid (18:2 omega 6) in serum phospholipids followed a similar pattern for the three treatments, with values of 0.96, 0.52 and 0.21. Thus, production of lung prostanoids of the 2-series could be modulated by varying the dietary omega 6/omega 3 ratio. This effect may be due in part to depression of phospholipid arachidonate, the precursor of 2-series eicosanoids.

Hairs from patients with maple syrup urine disease show a structural defect in the fiber cuticle

Models for the surface of cuticle cells in hair fibers consist of a monolayer of fatty acids covalently bound to the underlying protein membrane by thioester linkages. The most prominent of these fatty acids is 18-methyleicosanoic acid (C21a), the synthesis of which requires the oxidative decarboxylation of isoleucine. Maple syrup urine disease (MSUD) is caused by an inherited deficiency in the enzyme branched chain 2-oxo acid dehydrogenase, which leads to the accumulation of branched chain alpha-keto-acids derived from the amino acids, leucine, isoleucine, and valine. Transmission electron microscopy studies of developing hair fibers show a structural defect in the fiber shaft in hair from patients with MSUD. This defect is confined to the cuticle of the fiber, where the cuticle membrane directly apposes the intercellular material. Thus, the defect indicates that C21a is located exclusively on the upper surface of fiber cuticle cells. Lipid analysis of MSUD hairs has demonstrated significant changes in the relative abundance of the covalently bound fatty acids and an almost complete absence of C21a, whereas there was little difference in the amino acid composition compared with normal hair. These results provide further evidence for the existence of the surface lipid monolayer and its crucial role in cellular adhesion.

Membrane fatty acid composition and endothelial cell functional properties

In order to study the influence of endothelial cell fatty acid composition on various membrane related parameters, several in vitro methods were developed for manipulating the fatty acid content of human endothelial cell membranes. Changes in membrane fatty acid profile were induced by using fatty acid modified lipoproteins or free fatty acids. The largest changes in endothelial fatty acid composition were obtained by culturing the cells in media supplemented with specific free fatty acids. An increase in arachidonic acid content of endothelial phospholipids was induced by supplementation with saturated fatty acids or with arachidonic acid itself. A decrease in arachidonic acid content was obtained by supplementation with other unsaturated fatty acids. Under the experimental conditions used endothelial cells showed a low desaturase activity and a high elongase activity. Considerable alterations in membrane fatty acid composition did not greatly influence certain membrane related parameters such as polymorphonuclear leukocyte adherence and endothelial cell procoagulant activity. In general, for fatty acid modified endothelial cells an association between endogenous arachidonic acid content and total production of eicosanoids was found. This study demonstrates that considerable changes in membrane fatty acid profile affect endothelial cell arachidonic acid metabolism, but it also illustrates homeostasis at the level of endothelial cell functional activity.

Mechanisms of arachidonic acid-induced contractions of canine cerebral arteries

The effects of arachidonic acid in cerebral blood vessels has been examined using rings of canine cerebral arteries. Arachidonic acid produced dose-dependent contractions of this preparation even after mechanical removal of the endothelium. The contractions were not blocked by indomethacin or acetylsalicylic acid, both of which inhibit cyclooxygenase, but were inhibited by nordihydroguaiaretic acid which is a lipoxygenase inhibitor, BW 755c which blocks both pathways, and FPL 55712 which is an antagonist at leukotriene receptors. These data imply that arachidonic acid-induced contractions are mediated by products of the lipoxygenase pathway. Leukotrienes and cyclooxygenase products are generated by this preparation as shown by HPLC and radioimmunoassay and both LTC4 and LTD4 produce contractions in cerebral arteries lending further evidence in support of this suggestion.

The phytanic acid content of the lipids of bovine tissues and milk

In three steers which were given grass silage for six months, the content of phytanic acid (i.e. 3,7,11,15-tetramethyl-hexadecanoic acid) in plasma lipid increased to about 8% of the total fatty acids, whereas after this time the proportion in the total fatty acids of liver and heart lipids was about 1%, and only 0.1% in those of kidney lipids; the acid was present in trace amounts in adipose-tissue triglycerides and was apparently absent from brain lipids. In eight lactating cows which were given grass silage for about 3 months, the content of phytanic acid in the total long chain fatty acids of milk and of plasma was 0.7% and 13%, respectively. In the plasma lipids of both steers and lactating cows, phytanic acid constituted a substantial proportion of the total fatty acids of the triglycerides and phospholipids; the acid was present in lowest proportion in the cholesteryl esters.

Measurement of prostaglandin E3 and other eicosanoids in biologic samples using high pressure liquid chromatography and radioimmunoassay

A method to measure PGE3 in biologic samples is described. Complete resolution of PGE3 from PGE1 and PGE2 is achieved by reversephase high pressure liquid chromatography. Quantification is carried out by radioimmunoassay using an antibody directed against PGE2 that has high cross-reactivity with PGE3. Using this method, a marked increase in PGE3 production by mouse kidney tissue and in rat urine was demonstrated after supplemental feeding of omega-3 fatty acids. This method can also be applied to measurement of 6-keto-PGF1 alpha and TXB2 in the same samples.

Eicosanoic fatty acid reduction in the tibiotarsus of biotin-deficient chicks

Day-old male broiler chicks (Hubbard x Hubbard) were fed a purified diet containing biotin at 0 microgram/kg of diet (biotin-deficient) or 500 micrograms/kg of diet (biotin-adequate). Biotin-deficient (BD) chicks had decreased growth and feed efficiency and greater twisted leg and dermatitis symptoms than biotin-adequate (BA) chicks. Lipids in cortical bone of the tibiotarsi in BD chicks contained higher levels of linoleate, gamma-linolenate, and alpha-linolenate. Prostaglandin precursors, dihomo-gamma-linolenate (20:3 omega 6), arachidonate (20:4 omega 6), and eicosapentaenoate (20:5 omega 3) were all lower in BD chicks compared with BA chicks. Periosteal bone appositional and bone formation rates, and percent new bone formation were reduced in the tibiotarsi of BD chicks. Anatomically there were two different bone modeling patters at the mid-diaphysis. The cortex was thickest laterally in chicks fed the BA diet and thickest medially in chicks fed the BD diet. The quantitative differences in bone growth and the distinct bone modeling patterns, coupled with corresponding decreases in PG precursors, suggest that biotin deficiency may alter bone growth and modeling via a PG-dependent mechanism.

Tissue distribution of phytanic acid and its analogues in a kinship with Refsum's disease

Three of six kin were identified, by high performance thin layer chromatography, capillary gas chromatography and mass spectrometry, as having phytanic acid storage disease. Phytanic acid was found in triacylglycerol and, to a lesser degree, in phosphatidylcholine and free fatty acids. An unsaturated analogue of phytanic acid was additionally identified in plasma and erythrocyte triacylglycerols. In plasma, branched chain fatty acids were primarily localized in the low density lipoprotein fraction. The concentration of plasma major fatty acids was not affected by the presence of these branched chain fatty acids. In contrast to plasma, only small amounts of phytanic acid were found in cerebrospinal fluid and biopsied sural nerve. The nerve phytanate was mainly associated with triacylglycerol in epineurial and perineurial tissues. Lack of phytanate accumulation in sural endoneurium, even in cases with severe fiber degeneration, suggests that demyelination in Refsum's disease may not be due to myelin instability resulting from the incorporation of branched chain fatty acids into peripheral nerve membrane.

The analysis of fatty acid content and phospholipase A2 activity in placenta of cows with and without retained fetal membranes

The aim of the following study was the comparison of phospholipase A2 (PLA2) activity and fatty acids content in cows with and without retained fetal membranes. The activity of the enzyme and levels of fatty acids were measured in maternal and fetal placental tissues obtained from cows immediately after spontaneous parturition without (group A) and with (group B) retained fetal membranes. PLA2 activity was statistically significantly (P < 0.05) higher in group A than in group B, and was significantly lower in the fetal part than in the maternal part of placenta in both groups. The content of the examined fatty acids-myristic (14:0), palmitic (16:0), palmitoleic (16:1), stearic (18:0), oleic (18:1), linolenic (18:3), arachidic (20:0), arachidonic (20:4, AA)-was higher in group A than in B. Concentration of linoleic acid (18:2) showed the opposite relationship. There was a positive correlation between enzyme activity and content of det2ermined fatty acids. The results seem to confirm the bypothesis that the arachidonic acid pathway is altered in cases of retained placenta in cows.

Fatty acid fingerprints of Streptococcus mutans NCTC 10832 grown at various temperatures

Fatty acid fingerprints were determined gas chromatographically for Strepcococcus mutans NCTC 1082 which had been grown in batch brain heart infusion at a series of nine temperatures ranging from 29.0 to 40.0 degrees C. The major acids at all temperatures were n-palmitic and octadecenoic acids. Other acids detected at all temperatures included n-myristic, palmitoleic, n-stearic, and eicosenoic acids. An increase in temperature resulted in a decrease in the proportion of unsaturated to saturated fatty acids, indicating the importance of accurate temperature control in such gas-liquid chromatographic, chemotaxonomic studies.