Vorbeugende Behandlung des Atemnotsyndroms des Neugeborenen durch antepartale Glukokortikoidgabe (Betamethason)

Betamethason was administered to 105 patients with threatened premature labour at risk for respiratory distress syndrome (RDS) of the newborn. The most important indications were premature rupture of the membranes (30%) and premature labour (40%). The betamethason treatment was given between the 27. and 35. week of gestation. 79% of the patients delivered prior to 36 weeks of gestation, over 50% prior to 34 weeks gestation. The total incidence of RDS was 25%. Severe types of RDS (stage III and IV) were rare (7%). The mortality of RDS after betamethason treatment was 5.4%. After 32 weeks gestation the mortality from RDS was 0%. Severe types of RDS appear to occur more often in male than in female infants. The incidence of RDS was not lowered further by premature of the membranes. The lecithin/sphingomyelin(L/S)-ratio in the amniotic fluid following treatment with betamethason increased to over 2 in only 2/3 of the cases. The predictive value of the L/S ratio that respiratory distress syndrome of the newborn only occurs rarely with values over 2 was maintained after treatment with betamethason. Our rate in cases with an L/S ratio over 2 was 7.9%.

High-performance liquid chromatography method for quantifying sphingomyelin in rat brain

A rapid, reproducible and accurate high-performance liquid chromatographic (HPLC) method for the quantitative determination of sphingomyelin in rat brain was developed and validated using normal-phase silica gel column, acetonitrile-methanol-water (65:18:17 (v/v)) at a flow rate of 1 ml/min, isocratic elution, UV detection at 207 nm and 1,2-dimyristoyl-sn-glycero-3-phosphocholine as an internal standard. Total run time was 10.0 min. The calibration curve was linear over the range of 0.025-0.4 mg/ml sphingomyelin (R2>0.99). The intra-day coefficient of variation ranged from 1.4% to 2.2%. The average inter-day coefficient of variation over a period of 4 days was 3.1%. The practical limit of detection was 0.005 mg/ml with a quantification limit of 0.01 mg/ml.

Allometric dependence of the life span of mammal erythrocytes on thermal stability and sphingomyelin content of plasma membranes

Thermal stability of erythrocyte membrane is a measure for its ability to maintain permeability barrier at deleterious conditions. Hence, it could impact the resistance of erythrocytes against detrimental factors in circulation. In this study the thermostability of erythrocyte membranes was expressed by the temperature, T(go), at which the transmembrane gradient of ion concentration rapidly dissipated during transient heating. T(go) is the inducing temperature of the membrane transition that activated passive ion permeability at hyperthermia causing thermal hemolysis. A good allometric correlation of T(go) to the resistance against thermal hemolysis and the life span of erythrocytes were found for 13 mammals; sheep, cow, goat, dog, horse, man, rabbit, pig, cat, hamster, guinea pig, rat, and mouse. For the same group, the values of T(go) were strictly related to the sphingomyelin content of erythrocyte membranes. The residual ion permeability, P, was temperature activated from 38 to 57 degrees C with activation energy of 250+/-15 kJ/mol that strongly differed from that below 37 degrees C. The projected value of P at 37 degrees C was about half that of residual physiological permeability for Na+ and K+ that build ground for possible explanation of the life span vs membrane thermostability allometric correlation.

Long-term ethanol consumption impairs reverse cholesterol transport function of high-density lipoproteins by depleting high-density lipoprotein sphingomyelin both in rats and in humans

Moderate alcohol consumption has been linked to lower incidence of coronary artery disease due to increased plasma high-density lipoprotein (HDL), whereas heavy drinking has the opposite effect. Because of the crucial role of HDL in reverse cholesterol transport and positive correlation of HDL sphingomyelin (SM) content with cholesterol efflux, we have compared HDL SM content with its reverse cholesterol transport capacity both in rats fed ethanol on long-term basis and alcoholic individuals. In rats, SM HDL content was decreased in the ethanol group (-15.4%, P < .01) with a concomitant efflux decrease (-21.0%, P < .01) compared to that in controls. Similarly, HDL from the ethanol group, when compared with HDL from the control group, exhibited 13.8% (P < .05) less cholesterol uptake with control-group hepatocytes and 35.0% (P < .05) less cholesterol uptake with ethanol-group hepatocytes. Conversely, hepatocytes from the ethanol group, when compared with hepatocytes from the control group, exhibited 31.0% (P < .01) less cholesterol uptake with control-group HDL and 48.0% (P < .01) less with ethanol-group HDL. In humans, SM content in plasma HDL was also decreased in chronically alcoholic individuals without liver disease (-51.5%, P < .01) and in chronically alcoholic individuals with liver disease (-51.3%, P < .01), compared with nondrinkers. Concomitantly, in alcoholic individuals without liver disease, both efflux and uptake were decreased by 83.0% and 54.0% (P < .01), respectively, and in chronically alcoholic individuals with liver disease by 84.0% and 61.0% (P < .01), respectively, compared with nondrinkers. Based on these findings, we conclude that long-term ethanol consumption significantly impairs not only cholesterol efflux function of HDL by decreasing its SM content but also cholesterol uptake by affecting presumably hepatocyte receptors for HDL.

Elucidation of double bond position in unsaturated lipids by ozone electrospray ionization mass spectrometry

The position(s) of carbon-carbon double bonds within lipids can dramatically affect their structure and reactivity and thus has a direct bearing on biological function. Commonly employed mass spectrometric approaches to the characterization of complex lipids, however, fail to localize sites of unsaturation within the molecular structure and thus cannot distinguish naturally occurring regioisomers. In a recent communication [Thomas, M. C.; Mitchell, T. W.; Blanksby, S. J. J. Am. Chem. Soc. 2006, 128, 58-59], we have presented a new technique for the elucidation of double bond position in glycerophospholipids using ozone-induced fragmentation within the source of a conventional electrospray ionization mass spectrometer. Here we report the on-line analysis, using ozone electrospray mass spectrometry (OzESI-MS), of a broad range of common unsaturated lipids including acidic and neutral glycerophospholipids, sphingomyelins, and triacylglycerols. All lipids analyzed are found to form a pair of chemically induced fragment ions diagnostic of the position of each double bond(s) regardless of the polarity, the number of charges, or the adduct ion (e.g., [M - H](-), [M - 2H](2-), [M + H](+), [M + Na](+), [M + NH(4)](+)). The ability of OzESI-MS to distinguish lipids that differ only in the position of the double bonds is demonstrated using the glycerophosphocholine standards, GPCho(9Z-18:1/9Z-18:1) and GPCho(6Z-18:1/6Z-18:1). While these regioisomers cannot be differentiated by their conventional tandem mass spectra, the OzESI-MS spectra reveal abundant fragment ions of distinctive mass-to-charge ratio (m/z). The approach is found to be sufficiently robust to be used in conjunction with the m/z 184 precursor ion scans commonly employed for the identification of phosphocholine-containing lipids in shotgun lipidomic analyses. This tandem OzESI-MS approach was used, in conjunction with conventional tandem mass spectral analysis, for the structural characterization of an unknown sphingolipid in a crude lipid extract obtained from a human lens. The OzESI-MS data confirm the presence of two regioisomers, namely, SM(d18:0/15Z-24:1) and SM(d18:0/17Z-24:1), and suggest the possible presence of a third isomer, SM(d18:0/19Z-24:1), in lower abundance. The data presented herein demonstrate that OzESI-MS is a broadly applicable, on-line approach for structure determination and, when used in conjunction with established tandem mass spectrometric methods, can provide near complete structural characterization of a range of important lipid classes. As such, OzESI-MS may provide important new insight into the molecular diversity of naturally occurring lipids.

Status of caveolin-1 in various membrane domains of the bovine lens

Recent studies of the distribution and relative concentration of caveolin-1 in fractions of bovine lens epithelial and fiber cells have led to the novel concept that caveolin-1 may largely exist as a peripheral membrane protein in some cells. Caveolin-1 is typically viewed as a scaffolding protein for caveolae in plasma membrane. In this study, membrane from cultured bovine lens epithelial cells and bovine lens fiber cells were divided into urea soluble and insoluble fractions. Cytosolic lipid vesicles were also recovered from the lens epithelial cells. Lipid-raft domains were recovered from fiber cells following treatment with detergents and examined for caveolin and lipid content. Aliquots of all fractions were Western blotted for caveolin-1. Fluorescence microscopy and double immunofluorescence labeling were used to examine the distribution of caveolin-1 in cultured epithelial cells. Electron micrographs revealed an abundance of caveolae in plasma membrane of cultured lens epithelial cells. About 60% of the caveolin-1 in the epithelial-crude membrane was soluble in urea, a characteristic of peripheral membrane proteins. About 30% of the total was urea-insoluble membrane protein that likely supports the structure of caveolae. The remaining caveolin was part of cytosolic lipid vesicles. By contrast, most caveolin in the bovine lens fiber cell membrane was identified as intrinsic protein, being present at relatively low concentrations in caveolae-free lipid raft domains enriched in cholesterol and sphingomyelin. We estimate that these domains occupied 25-30% of the fiber cell membrane surface. Thus, the status of caveolin-1 in lens epithelial cells appears markedly different from that in fiber cells.

Evaluation of lung maturity by amniotic fluid analysis in equine neonate

The aim of this study was to gather useful new data for evaluation of lung maturity in the neonatal foal. Because equine neonatal intensive therapy is very expensive, a precocious diagnosis could help to express a prognosis and to offer a respiratory support early after birth, increasing the survival rate and reducing complications. Amniotic fluid was collected at parturition on n=18 mares. Lamellar bodies were isolated in the amniotic fluid and measured with transmission electron microscopy (TEM). Furthermore two tests on amniotic fluid that are commonly used in humane medicine were utilized: lecithin/sphingomyelin ratio (L/S) and lamellar body count (LBC). L/S ratio was determined using thin layer chromatography (TLC) and, for the first time in equine amniotic fluid, with high performance liquid chromatography (HPLC). LBC was performed with an automated blood cell counter. The mean of the L/S ratio obtained in mature foals was 2.5 with TLC and 2.7 with HPLC. The mean LBC in the same group was 48x10(3)/microL. The Spearman's Rank correlation test found a significant correlation between TLC and Apgar score (R=0.66, p<0.01), between TLC and cord pH (R=0.65, p<0.05), between HPLC and Apgar score (R=0.63, p<0.01) and between cord pH and Apgar score (R=0.82, p<0.01). The Student's t-test did not found a significant difference between L/S ratio performed with TLC and with HPLC. These methods may be useful for evaluation of lung maturity in the equine species, but further studies on a large number of mature and premature foals are necessary to establish equine pulmonary maturity standards.

Factors affecting the concentration of sphingomyelin in bovine milk

Sphingomyelin is a phospholipid located in the outer leaflet of the plasma membrane of most cells and is a component of the milk fat globule membrane. Sphingomyelin and its digestion products participate in several antiproliferative pathways that may suppress oncogenesis. Although milk and dairy products are important sources of sphingomyelin in the human diet, little is known about factors that influence sphingomyelin concentrations in milk fat or whether concentrations can be modified via the nutrition of cows. Sphingomyelin concentrations were determined in milk from Holstein and Jersey cows matched for parity and stage of lactation. Sphingomyelin was more concentrated in milk fat from Holstein cows than in milk fat from Jersey cows (1,044 vs. 839 microg/g of fat). Concentrations in whole milk did not differ because of greater milk fat content for milk from Jerseys. Differences between breeds may be related to the greater fat globule size in milk from Jerseys. Sphingomyelin content in whole milk increased with increasing days in milk because of associated increases in milk fat content. Regardless of breed, primiparous cows had greater amounts of stearic acid and less palmitic acid in sphingomyelin than did older cows. The sphingomyelin concentration in milk fat of cows in a commercial Jersey herd was lower for cows in their fourth or greater parity. Sphingomyelin content in whole milk was greater for cows in late lactation because of greater milk fat content. Feed restriction of multiparous Holstein cows to 37% of ad libitum dry matter intake increased milk fat content but did not affect milk sphingomyelin content or milk fat globule size. Supplementation of the diet with 4% soybean oil did not affect milk composition, sphingomyelin content, or milk fat globule size. Milk was sampled seasonally from 7 herds throughout Illinois during a 2-yr period. Sphingomyelin concentration in milk fat was greatest during summer and least during winter, but whole milk concentrations did not vary across seasons. We conclude that 1) sphingomyelin content of milk fat is greater in milk from Holsteins than that from Jerseys, 2) sphingomyelin content in whole milk increases with stage of lactation, and 3) sphingomyelin content of milk fat is greater during summer. However, efforts to produce milk with a greater sphingomyelin content through altering management and nutrition are unlikely to be successful.

Liquid chromatography with dual parallel mass spectrometry and 31P nuclear magnetic resonance spectroscopy for analysis of sphingomyelin and dihydrosphingomyelin

Liquid chromatography coupled to atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) mass spectrometry (MS), in parallel, was used for simultaneous detection of bovine milk sphingolipids (BMS). APCI-MS mass spectra exhibited mostly ceramide-like fragment ions, [Cer-H(2)O+H](+) and [Cer-2H(2)O+H](+), which were used to identify individual molecular species of BMS according to fatty acyl chain length:degree of unsaturation and long-chain base (LCB). ESI-MS was used to confirm the molecular weights of BMS species. Both sphingomyelin (SM) and dihydrosphingomyelin (DSM) molecular species were identified, with DSM species constituting 20% of BMS. Approximately 56 to 58% of DSM species contained a d16:0 LCB, while 34 to 37% contained a d18:0 LCB. Approximately 26 to 30% of SM species contained a d16:1 LCB, while 57 to 60% contained a d18:1 LCB. BMS species contained both odd and even carbon chain lengths. The most abundant DSM species contained a d16:0 LCB with a 22:0, 23:0 or 24:0 fatty acyl chain, while the most abundant SM species contained a d18:1 LCB with a 16:0 or 23:0 fatty acyl chain. (31)P NMR spectroscopy was used to conclusively confirm that DSM is a dietary component in BMS.

The differing embryonic origins of retinal and uveal (iris/ciliary body and choroid) melanosomes are mirrored by their phospholipid composition

The phospholipids present in uveal (iris/ciliary body and choroid) and retinal bovine ocular melanosomes were identified using mass spectrometry. Similar phospholipid content is found for the two types of uveal melanosome, with sphingomyelin being the major species. Significant differences are found between the uveal and retinal melanosome. Glycerophosphoethanolamine (GPEtn) is the major species in the retinal pigment epithelium (RPE); 93% of the GPEtn contain polyunsaturated fatty acids, notably docosahexanoic acid and arachidonic acid, in the sn-2 position. RPE melanosomes also contain detectable quantities of glycerophosphoserine and glycerophosphate; these species were not detected in the uveal samples. While the structural and functional roles of melanosomal lipids largely remain to be determined, these different lipid compositions reported herein offer new insights into the roles of melanosomes in the different ocular tissues.

Resistance to alkyl-lysophospholipid-induced apoptosis due to downregulated sphingomyelin synthase 1 expression with consequent sphingomyelin- and cholesterol-deficiency in lipid rafts

The ALP (alkyl-lysophospholipid) edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine; Et-18-OCH3) induces apoptosis in S49 mouse lymphoma cells. To this end, ALP is internalized by lipid raft-dependent endocytosis and inhibits phosphatidylcholine synthesis. A variant cell-line, S49AR, which is resistant to ALP, was shown previously to be unable to internalize ALP via this lipid raft pathway. The reason for this uptake failure is not understood. In the present study, we show that S49AR cells are unable to synthesize SM (sphingomyelin) due to down-regulated SMS1 (SM synthase 1) expression. In parental S49 cells, resistance to ALP could be mimicked by small interfering RNA-induced SMS1 suppression, resulting in SM deficiency and blockage of raft-dependent internalization of ALP and induction of apoptosis. Similar results were obtained by treatment of the cells with myriocin/ISP-1, an inhibitor of general sphingolipid synthesis, or with U18666A, a cholesterol homoeostasis perturbing agent. U18666A is known to inhibit Niemann-Pick C1 protein-dependent vesicular transport of cholesterol from endosomal compartments to the trans-Golgi network and the plasma membrane. U18666A reduced cholesterol partitioning in detergent-resistant lipid rafts and inhibited SM synthesis in S49 cells, causing ALP resistance similar to that observed in S49AR cells. The results are explained by the strong physical interaction between (newly synthesized) SM and available cholesterol at the Golgi, where they facilitate lipid raft formation. We propose that ALP internalization by lipid-raft-dependent endocytosis represents the retrograde route of a constitutive SMS1- and lipid-raft-dependent membrane vesicular recycling process.

Ceramide and sphingomyelin species of fibroblasts and neurons in culture

The ceramide (Cer) and sphingomyelin (SM) species of cultured differentiated rat cerebellar granule cells and human fibroblasts were characterized by electrospray ionization-mass spectrometry. We identified 35 different species of Cer and 18 species of SM in human fibroblasts, and 35 different species of Cer and 9 species of SM were characterized in rat neurons. The main Cer species of rat cerebellar granule cells contained d18:1 sphingosine linked with palmitic, stearic, or nervonic fatty acid, and the two main SM species were d18:1,16:0 and d18:1,18:0. Both sphingolipids were enriched in detergent-resistant membranes (DRMs; or lipid rafts), and significant differences were found in the sphingolipid patterns of DRMs and of detergent-soluble fractions (DSF) from these cells. In human fibroblasts, the main Cer species were d18:1,16:0, d18:2,16:0, d18:1,24:0, d18:2,24:0, d18:1,24:1, and d18:2,24:1; the most represented species of SM were d18:1,16:0, d18:1,24:0, and d18:1,24:1. In these cells, SM was highly enriched in DRMs and Cer was mainly associated with DSF, and the species found in DRMs were markedly different from those found in DSF.

Liquid chromatography with dual parallel mass spectrometry and 31P nuclear magnetic resonance spectroscopy for analysis of sphingomyelin and dihydrosphingomyelin

Liquid chromatography coupled to atmospheric pressure chemical ionization (APCI) and electrospray ionization (ESI) mass spectrometry (MS), in parallel, was used for detection of bovine brain and chicken egg sphingolipids (SLs). APCI-MS mass spectra exhibited mostly ceramide-like fragment ions, [Cer-H(2)O+H](+) and [Cer-2H(2)O+H](+), whereas ESI-MS produced mostly intact protonated molecules, [M+H](+). APCI-MS/MS and MS(3) were used to differentiate between isobaric SLs. APCI-MS/MS mass spectra exhibited long-chain base related fragments, [LCB](+) and [LCB-H(2)O](+), that allowed the sphinganine backbone to be differentiated from the sphingenine backbone. Fragments formed from the fatty amide chain, [FA(long)](+) and [FA(short)](+), allowed an overall fatty acid composition to be determined. The presence of both dihydrosphingomyelin (DSM) and sphingomyelin (SM) sphingolipid classes was confirmed using (31)P NMR spectroscopy.

Sequential pressurized liquid extraction to determine brain-originating fatty acids in meat products as markers in bovine spongiform encephalopathy risk assessment studies

A new approach using sequential pressurized liquid extraction described recently [J. Poerschmann, R. Carlson, J. Chromatogr. A, 1127 (2006) 18-25] was applied to determine lipid markers originating from central nervous system (CNS) tissue of cows in heat-processed sausages. These studies are very important in quality control as well as risk assessment studies in the face of the bovine spongiform encephalopathy (BSE) crisis. Diagnostic CNS lipid markers, which should not be present in meat products without CNS addition, were recognized on complete transesterification as polar 2-hydroxy-fatty acids (2OH-24:0, 2OH-24:1, 2OH-22:0, 2OH-18:0, shorthand designation) as well as odd-numbered non-branched fatty acids beyond C(22). An array of other fatty acids including lignoceric acid (24:0), nervonic acid (24:1), arachidonic acid (20:4), and polyunsaturated nC(22)-surrogates are strongly related to CNS lipids, but occur as traces in meat products without CNS addition as well, thus reducing their value as diagnostic markers. Samples including meat products without CNS addition, meat with 3% CNS addition, as well as pure CNS homogenates, were subjected to sequential PLE (pressurized liquid extraction) consisting of two steps: n-hexane/acetone 9:1 (v/v) extraction at 50 degrees C to remove neutral lipids, followed by chloroform/methanol 1:4 (v/v) extraction at 110 degrees C to isolate polar CNS lipids (two 10 min PLE cycles each). To enhance the fractionation efficiency, cyanopropyl modified silica as well as chemically not modified silica sorbent was used at the outlet of the PLE cartridge to retard polar lipids in the first extraction step. This method proved superior to widely distributed exhaustive lipid extraction followed by solid-phase extraction (SPE) using silica regarding lipid recoveries and clear-cut boundaries between lipid classes. Methodological studies showed that the alcoholysis using trimethylchlorosilane/methanol (1:9, v/v) is an excellent method for the complete transesterification of lipids and quantitative formation of methyl esters.

The isolation and structure of membrane lipid rafts from rat brain

The action of detergents in the isolation of detergent-resistant membrane fractions from rat brain is reported. Triton X-100 treatment of whole rat brain homogenate at 4 degrees C produced detergent-resistant membranes with a density of 1.07g/ml compared with Brij96 where the density of the membrane was only 1.05g/ml. The DRM fractions isolated using Triton X-100 are considerably heavier than those isolated from homogenates treated with Brij96. The major polar lipid composition of DRMs derived from Brij96 treated homogenates have a higher proportion of aminophospholipids compared with choline phospholipids than Triton X-100 derived DRMs; this may indicate that DRMs from Brij96 treated homogenates are more closely related to the parent membrane in lipid composition. Solubilization by Triton X-100 at higher temperatures resulted in the appearance of a second detergent-resistant membrane fraction distinctly lighter in density than the membrane recovered at density 1.07g/ml. Analysis of phospholipid composition of the brain homogenate during detergent treatment for up to 30min at 37 degrees C showed a decreasing proportion of sphingomyelin. Treatment of homogenates at 37 degrees C appears to activate phospholipases/sphingomyelinases that may alter the lipid content of isolated DRMs. The presence of K+/Mg2+ with Brij96 treatment results in DRM fractions with significantly thicker bilayers and of larger vesicle diameter than DRMs isolated from either Triton X-100 or Brij96 treated homogenates in the absence of cations.

High recovery HPLC separation of lipid rafts for membrane proteome analysis

Proteomic analysis of complex samples can be facilitated by protein fractionation prior to enzymatic or chemical fragmentation combined with MS-based identification of peptides. Although aqueous soluble protein fractionation by liquid chromatography is relatively straightforward, membrane protein separations have a variety of technical challenges. Reversed-phase high performance liquid chromatography (RP-HPLC) separations of membrane proteins often exhibit poor recovery and bandwidths, and generally require extensive pretreatment to remove lipids and other membrane components. Human brain tissue lipid raft protein preparations have been used as a model system to develop RP-HPLC conditions that are effective for protein fractionation, and are compatible with downstream proteomic analytical workflows. By the use of an appropriate RP column material and operational conditions, human brain membrane raft proteins were successfully resolved by RP-HPLC and some of the protein components, including specific integral membrane proteins, identified by downstream SDS-PAGE combined with in-gel digestion, or in-solution digestion and LC-MS/MS analysis of tryptic fragments. Using the described method, total protein recovery was high, and the repeatability of the separation maintained after repeated injections of membrane raft preparations.

Effect of 2,6-di-O-methyl-alpha-cyclodextrin on hemolysis and morphological change in rabbit's red blood cells

The effects of 2,6-di-O-methyl-alpha-cyclodextrin (DM-alpha-CyD) on hemolysis and morphological changes in rabbit's red blood cells (RBC) were examined, compared with those of alpha-cyclodextrin (CyD) and 2-hydoxypropyl-alpha-cyclodextrin (HP-alpha-CyD). The hemolytic activity of alpha-CyDs increased in the order of HP-alpha-CyD<alpha-CyD<DM-alpha-CyD. The three alpha-CyDs induced morphological changes of RBC from discocyte to stomatocyte. At the same concentration (3mM) of alpha-CyDs, DM-alpha-CyD and alpha-CyD released phospholipids, rather than cholesterol, and DM-alpha-CyD markedly released proteins from RBC membranes, compared to alpha-CyD and HP-alpha-CyD. The treatment of RBC with DM-alpha-CyD lowered the extent of a fluorescent sphingomyelin analogue from lipid rafts of RBC membranes in a concentration-dependent manner. These results suggest that DM-alpha-CyD has higher hemolytic and morphological change activity than alpha-CyD and HP-alpha-CyD through more extraction of phospholipids including sphingomyelin and proteins, not cholesterol, from RBC membranes than alpha-CyD and HP-alpha-CyD.

Lipid Remodeling of Murine Epididymosomes and Spermatozoa During Epididymal Maturation1

We have isolated vesicular structures from mouse epididymal fluid, referred to as epididymosomes. Epididymosomes have a roughly spherical aspect and a bilayer membrane, and they are heterogeneous in size and content. They originate from the epididymal epithelium, notably from the caput region, and are emitted in the epididymal lumen by way of apocrine secretion. We characterized their membranous lipid profiles in caput and cauda epididymidal fluid samples and found that epididymosomes were particularly rich in sphingomyelin (SM) and arachidonic acid. The proportion of SM increased markedly during epididymal transit and represented half the total phospholipids in cauda epididymidal epididymosomes. The cholesterol:phospholipid ratio increased from 0.26 in the caput to 0.48 in the cauda epididymidis. Measures of epididymosomal membrane anisotropy revealed that epididymosomes became more rigid during epididymal transit, in agreement with their lipid composition. In addition, we have characterized the membrane lipid pattern of murine epididymal spermatozoa during their maturation. Here, we have shown that mouse epididymal spermatozoa were distinguished by high percentages of SM and polyunsaturated membranous fatty acids (PUFAs), principally represented by arachidonic, docosapentanoic, and docosahexanoic acids. Both SM and PUFA increased throughout the epididymal tract. In particular, we observed a threefold rise in the ratio of docosapentanoic acid. Epididymal spermatozoa had a constant cholesterol:phospholipid ratio (average, 0.30) during epididymal transit. These data suggest that in contrast with epididymosomes, spermatozoal membranes seem to become more fluid during epididymal maturation.

Porphyromonas gingivalis lipids and diseased dental tissues

BACKGROUND/AIM

Porphyromonas gingivalis synthesizes several classes of dihydroceramides and at least one of these lipid classes promotes proinflammatory secretory reactions in gingival fibroblasts as well as alters fibroblast morphology in culture. The purpose of this investigation was to determine whether the dihydroceramide lipids of P. gingivalis are recovered in lipid extracts of subgingival plaque, diseased teeth, and diseased gingival tissue samples.

METHODS

Lipids were extracted from P. gingivalis, subgingival plaque, subgingival calculus, teeth laden with gross accumulations of subgingival calculus, and gingival tissue samples obtained from chronic severe periodontitis sites. Lipid samples were analyzed by gas chromatography-mass spectrometry as trimethylsilyl derivatives or by electrospray-mass spectrometry as underivatized products. High-performance liquid chromatography fractions of P. gingivalis lipids and gingival tissue lipids were also analyzed by electrospray-mass spectrometry analysis.

RESULTS

P. gingivalis phosphorylated dihydroceramides were recovered in lipid extracts of subgingival plaque, subgingival calculus, calculus contaminated teeth, and diseased gingival tissue samples. However, the distribution of phosphorylated dihydroceramides varied between these samples.

CONCLUSION

Subgingival plaque, subgingival calculus, diseased teeth, and gingival tissue are contaminated with phosphorylated dihydroceramides produced by P. gingivalis. The previously reported biological activity of these substances together with the recovery of these lipids at periodontal disease sites argues strongly for their classification as virulence factors in promoting chronic inflammatory periodontal disease.

High performance liquid chromatography-tandem mass spectrometry of phospholipid molecular species in eggs from hens fed diets enriched in seal blubber oil

The total lipid fraction of eggs from hens fed diets enriched in seal blubber oil (1.25-5.0% SBO) was directly analysed with normal-phase high performance liquid chromatography coupled on-line with electrospray ionization ion-trap tandem mass spectrometry (HPLC-ESI-MS-MS) for the identification of the molecular species of phospholipids (PLs). The species of phosphatidylethanolamine (PE) and phosphatidylinositol (PI) were all detected as the [M-H](-) ions. The phosphatidylcholine (PC), sphingomyelin (Sph) and lysophosphatidylcholine (LPC) classes, were detected as formate adducts [M+HCOO](-). Tandem MS of PE and PI showed the loss of the carboxylate anions, and, for PI, also the loss of water and inositol. Product ion spectrum of PC, LPC and Sph contained only the [M-CH(3)](-) ion fragment. Feeding different levels of SBO for 5 weeks resulted in a significant increase of PE, PC and PI molecular species carrying eicosapentaenoic acid (C(20:5 omega3), EPA), docosapentaenoic acid (C(22:5 omega3), DPA) and docosahexaenoic acid (C(22:6 omega3), DHA), but not Sph nor LPC. The highest increase of the omega3/omega6 ratio occurred for PE and PC. On the contrary, PI was less affected by the increase of SBO in the diet.

Lipid composition in human breast milk from Granada (Spain): changes during lactation

OBJECTIVE

To determine possible differences of composition in the course of lactation, phospholipid (PL) classes (phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylcholine, and sphingomyelin) and fatty acid composition of PL and triacylglycerol (TGs) fractions of milk fat were analyzed in 66 samples from mothers from Granada (Spain) who gave birth to full-term infants. Analyses included colostrum, transitional milk, and mature milk.

METHODS

After milk fat extraction, PLs and TGs were separated by thin-layer chromatography and fatty acids of each fraction were converted into their methyl esters, which were analyzed by gas chromatography. PL classes were determined by high-performance liquid chromatography using an evaporative light-scattering detector.

RESULTS

Mature human milk showed a lower content (P = 0.020) of PLs than did the other milks. Percentage of sphingomyelin was constant for all stages of lactation, whereas the percentage of phosphatidylcholine in mature milk was significantly lower (P < 0.05) than in colostrum and transitional milk. TGs in mature human milk contained lower percentages (P < 0.001) of arachidonic acid, docosahexaenoic acid, and nervonic acid. Docosahexaenoic acid and nervonic acid also showed a significant decrease (P < 0.001) in total PLs from colostrum and mature milk.

CONCLUSIONS

The composition of PL classes and fatty acids in PLs and TGs in milk of mothers in Granada (Southern Europe) is different from that in milk from mothers in other parts of the world. In addition, the ratio of long-chain polyunsaturated fatty acids delivered in the form of PLs to long-chain polyunsaturated fatty acids delivered in the form of triacylglycerols diminishes as lactation proceeds.

Comparison of the TDx-FLM II and lecithin to sphingomyelin ratio assays in predicting fetal lung maturity

OBJECTIVE

We evaluated the usefulness of the TDx-FLM II and lecithin to sphingomyelin (L/S) ratio assays in predicting fetal lung maturity.

STUDY DESIGN

We retrospectively reviewed 218 consecutive paired TDx-FLM II and L/S ratio results. Women who delivered viable infants within 72 hours of amniotic fluid collection (n=109) were included in the analysis of sensitivity and specificity. Concordance between tests was determined for all women tested during the study period, and in the subset of women who delivered viable infants within 72 hours of amniotic fluid collection.

RESULTS

There were 9 respiratory distress syndrome (RDS)-affected infants born during the study period. Both the TDx-FLM II and L/S ratios had 100% sensitivity in detecting RDS at their best apparent cut-offs. There was a trend towards increased specificity of the L/S ratio compared with the TDx-FLM II (80% for L/S vs 73% for FLM II). The overall concordance between the TDx-FLM II and L/S ratio was approximately 75%.

CONCLUSION

The TDx-FLM II and L/S ratios are both sensitive tests for RDS; however, there is not good concordance between the two. The results provide new insight into the optimal use, in sequential or reflex cascade testing, of the TDx-FLM II and L/S ratio.

A lipidomic study of the effects of N-methyl-N'-nitro-N-nitrosoguanidine on sphingomyelin metabolism

Systems biology is a new and rapidly developing research area in which, by quantitatively describing the interaction among all the individual components of a cell, a systems-level understanding of a biological response can be achieved. Therefore, it requires high-throughput measurement technologies for biological molecules, such as genomic and proteomic approaches for DNA/RNA and protein, respectively. Recently, a new concept, lipidomics, which utilizes the mass spectrometry (MS) method for lipid analysis, has been proposed. Using this lipidomic approach, the effects of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) on sphingomyelin metabolism, a major class of sphingolipids, were evaluated. Sphingomyelin molecules were extracted from cells and analyzed by matrix-assisted laser desorption ionization-time of flight MS. It was found that MNNG induced profound changes in sphingomyelin metabolism, including the appearance of some new sphingomyelin species and the disappearance of some others, and the concentrations of several sphingomyelin species also changed. This was accompanied by the redistribution of acid sphingomyelinase (ASM), a key player in sphingomyelin metabolism. On the other hand, imipramine, an inhibitor of ASM, caused the accumulation of sphingomyelin. It also prevented some of the effects of MNNG, as well as the redistribution of ASM. Taken together, these data suggested that the lipidomic approach is highly effective for the systematic analysis of cellular lipids metabolism.

Epidermal growth factor receptors are localized to lipid rafts that contain a balance of inner and outer leaflet lipids: a shotgun lipidomics study

The epidermal growth factor (EGF) receptor partitions into lipid rafts made using a detergent-free method, but is extracted from low density fractions by Triton X-100. By screening several detergents, we identified Brij 98 as a detergent in which the EGF receptor is retained in detergent-resistant membrane fractions. To identify the difference in lipid composition between those rafts that harbored the EGF receptor (detergent-free and Brij 98-resistant) and those that did not (Triton X-100-resistant), we used multidimensional electrospray ionization mass spectrometry to perform a lipidomics study on these three raft preparations. Although all three raft preparations were similarly enriched in cholesterol, the EGF receptor-containing rafts contained more ethanolamine glycerophospholipids and less sphingomyelin than did the non-EGF receptor-containing Triton X-100 rafts. As a result, the detergent-free and Brij 98-resistant rafts exhibited a balance of inner and outer leaflet lipids, whereas the Triton X-100 rafts contained a preponderance of outer leaflet lipids. Furthermore, in all raft preparations, the outer leaflet phospholipid species were significantly different from those in the bulk membrane, whereas the inner leaflet lipids were quite similar to those found in the bulk membrane. These findings indicate that the EGF receptor is retained only in rafts that exhibit a lipid distribution compatible with a bilayer structure and that the selection of phospholipids for inclusion into rafts occurs mainly on the outer leaflet lipids.

Phospholipid profile of developing heart of rats exposed to low-protein diet in pregnancy

Although the myocardial phospholipid and fatty acid content have profound effects on the heart function, very little information is available on the effects of restricted maternal protein intake during pregnancy on the phospholipid profile and fatty acid content of the developing heart. The present study was therefore undertaken to examine the effect of pregnant dams fed diets containing either 180 (normal) or 90 (low) g/kg casein diet for 2 wk before mating and throughout pregnancy on myocardial phospholipid and fatty acid content of male offspring. Whereas no changes in phosphatidylcholine and phosphatidylethanolamine were detected, increases in lysophosphatidylcholine, phosphatidylserine, and sphingomyelin were seen in the hearts of offspring in the low-protein (LP) group. Analysis of cardiac fatty acids revealed that although the saturated fatty acid (myristate, palmitate, and stearate) levels were significantly reduced, the unsaturated fatty acid (linoleate, arachidonate, and decosahexanoate) levels were significantly increased in the developing heart in the LP group. Furthermore, assessment of nuclear transcription factors involved in regulation of cardiac metabolism revealed a decrease in myocyte enhancer factor-2C mRNA levels in the LP group, whereas an increase in the mRNA amount of peroxisome proliferator-activated receptor-alpha was observed in this group. These results demonstrate that maternal LP diet can induce changes in the phospholipid profile and fatty acid content of the developing heart, which may have implications for metabolism of the neonatal heart.