Individual Subfractions Research Articles

Aging behaviour and mechanical characterisation of maltenes and asphaltenes

The analysis of bitumen is challenging due to its complex and ever-changing chemical composition. Fractionation techniques based on solubility and polarity properties facilitate the examination process, shedding more light on composition, structure and aging behaviour. However, these separation experiments are often performed post-aging, making it difficult to understand the behaviour and mechanical properties of individual subfractions. Hence, the focus of this study was to separate maltenes and asphaltenes in large quantities and age them at various temperatures (80, 130 and 180°C), followed by analysis with chemical and mechanical methods. Results showed that both maltenes and asphaltenes display viscoelastic properties: maltenes are more viscous, while asphaltenes are more elastic compared to the base binder. Maltenes aged at 180°C became extremely stiff with a nearly temperature-independent phase angle, while asphaltenes aged at 130°C exhibited the stiffest and most elastic behaviour. Decomposition of sulfoxides at high temperatures was observed for both fractions, while additional decarboxylation occurred in the asphaltenes. During the aging of the maltenes, a significant amount of asphaltenes were formed, which most likely originated from both the aromatics and resins fraction. Furthermore, no major discrepancies between oxidation products in bitumen and in the maltenes were detected, indicating that asphaltenes might not crucially influence the qualitative aging process. This study demonstrated a possible approach for obtaining bituminous subfractions in large quantities, allowing for a detailed analysis of their mechanical and aging properties.

LDL subfractions are associated with incident cardiovascular disease in the Malmö Prevention Project Study

Background and aimsAfter assessing the risk for cardiovascular disease (CVD) based on traditional risk factors, decisions concerning lipid lowering therapy might remain uncertain. To investigate whether lipoprotein subfraction levels could aid these decisions, we assessed the association between lipoprotein subfractions and CVD, after adjustment for traditional risk factors including standard lipids. MethodsUsing a case-cohort design, participants were randomly drawn from the Malmö Prevention Project (MPP), a population-based prospective study of 18,240 participants, and supplemented with additional incident CVD events (5764 participants, 1784 CVD events). ResultsLow density lipoprotein particle number (LDL-P) and individual subfractions ranging in size from very-small to large were associated with CVD (continuous p value (pcont) < 0.001) while adjusting for age, sex, hypertension, smoking, and diabetes. After further adjustment for LDL-C, HDL-C, and triglycerides, very small LDL subfraction (b) (LDL-VS (b)) remained associated with CVD (HR = 1.23, 95% CI, 1.06 to 1.43 for top vs. bottom quartile, pcont = 0.03). Among participants with low/intermediate risk [without diabetes and with LDL-C <3.36 mmol/L (<130 mg/dL)], the fully adjusted HR for LDL-small (top vs. bottom quartile) was 1.48 (95% CI 1.02 to 2.17, pcont = 0.03). Among those with very-high risk (>20% 10-year risk of CVD), LDL-VS(a) and LDL-VS(b) were associated with CVD in fully adjusted models (HR = 1.37, 95% CI 1.12 to 1.67 and HR = 1.28, 95% CI 1.07 to 1.53, respectively, pcont≤0.03). ConclusionsSmaller LDL particles are associated with incident CVD independently of traditional risk factors, including standard lipids, in participants with low/intermediate and very-high risk, who might benefit from improved risk assessment.

Rapid identification of α-glucosidase inhibitors from Phlomis tuberosa by Sepbox chromatography and thin-layer chromatography bioautography.

Alpha-glucosidase inhibitors currently form an important basis for developing novel drugs for diabetes treatment. In our preliminary tests, the ethyl acetate fraction of Phlomis tuberosa extracts showed significant α-glucosidase inhibitory activity (IC₅₀ = 100 μg/mL). In the present study, a combined method using Sepbox chromatography and thin-layer chromatography (TLC) bioautography was developed to probe α-glucosidase inhibitors further. The ethyl acetate fraction of P. tuberosa extracts was separated into 150 individual subfractions within 20 h using Sepbox chromatography. Then, under the guidance of TLC bioautography, 20 compounds were successfully isolated from these fractions, including four new diterpenoids [14-hydroxyabieta-8,11,13-triene-11-carbaldehyde-18-oic-12-carboxy-13-(1-hydroxy-1-methylethyl)-lactone (1), 14-hydroxyabieta-8,11,13-triene-17-oic-12-carboxy-13-(1-hydroxy-1-methylethyl)-lactone (2), 14,16-dihydroxyabieta-8,11,13-triene-15,17-dioic acid (3), and phlomisol (15,16-eposy-8,13(16),14-labdatrien-19-ol) (4)], and 16 known compounds. Activity estimation indicated that 15 compounds showed more potent α-glucosidase inhibitory effects (with IC50 values in the range 0.067–1.203 mM) than the positive control, acarbose (IC50 = 3.72 ± 0.113 mM). This is the first report of separation of α-glucosidase inhibitors from P. tuberosa.

Abstract 409: Site-Specific Solvent Exposure of Major Apolipoproteins in Human High-Density Lipoprotein Complexes of Different Composition and Diameter

It is believed that the interactions of high density lipoproteins (HDL) with different plasma enzymes are partly determined by the site specific solvent exposure of apolipoproteins in HDL. Ultra-centrifugally isolated human HDL was separated into subpopulations containing both major apolipoproteins apoA-I and apoA-II (termed LpA-I/A-II) and only apoA-I (termed LpA-I) using thiopropyl sepharose chromatography. LpA-I/A-II and LpA-I were further separated into three sub-fractions based on the particle diameter utilizing fast performance liquid chromatography. Individual sub-fractions were subjected to partial acetylation; the extent of acetylation that represents the solvent exposure was quantified by mass spectrometry (MS). LpA-I of ∼85 Å, demonstrated solvent exposure variations for Lys residues in apoA-I in the range of 9-55%. Lys 133 (helix 5) and Lys 226 (helix 10) showed the highest solvent exposure of 54-55%. Surprisingly Lys residues 238 and 239 showed the lowest exposure of 9-10%. The rest of the Lys residues located in N-term through helix 10 ranged from 12-40% demonstrating distinctive differences among specific sites of exposure. The presence of apoA-II in comparable diameter LpA-I/A-II showed similar solvent exposure for apoA-I, implying the non-perturbing nature of apoA-II on apoA-I conformation. Limited proteolysis experiments resulted in similar fragment patterns for apoA-I in LpA-I and LpA-I/A-II, agreeing with mass spectrometry observations. Furthermore, proteolysis demonstrated that apoA-II in HDL is less susceptible to proteolysis compared to apoA-I in HDL. Confirming this observation further, the extent of acetylation of individual Lys residues of apoA-II in LpA-I/A-II demonstrated overall low solvent exposure (9-14%) by MS. Subtle solvent exposure differences were seen among particles of different diameter (75 Å vs 110 [[Unable to Display Character: &amp;#506;]]). These novel findings bring out conformational details of major apolipoprotein in different HDL particles. Assessment of site specific solvent exposure of minor HDL apolipoproteins including apoE, apoD, apoCs, apoM and determination of their specific preference for LpA-I vs LpA-I/A-II are currently underway implementing high throughput mass spectrometry techniques.

Speciated Human High-Density Lipoprotein Protein Proximity Profiles

It is expected that the attendant structural heterogeneity of human high-density lipoprotein (HDL) complexes is a determinant of its varied metabolic functions. To determine the structural heterogeneity of HDL, we determined major apolipoprotein stoichiometry profiles in human HDL. First, HDL was separated into two main populations, with and without apolipoprotein (apo) A-II, LpA-I and LpA-I/A-II, respectively. Each main population was further separated into six individual subfractions using size exclusion chromatography (SEC). Protein proximity profiles (PPPs) of major apolipoproteins in each individual subfraction was determined by optimally cross-linking apolipoproteins within individual particles with bis(sulfosuccinimidyl) suberate (BS(3)), a bifunctional cross-linker, followed by molecular mass determination by MALDI-MS. The PPPs of LpA-I subfractions indicated that the number of apoA-I molecules increased from two to three to four with an increase in the LpA-I particle size. On the other hand, the entire population of LpA-I/A-II demonstrated the presence of only two proximal apoA-I molecules per particle, while the number of apoA-II molecules varied from one dimeric apoA-II to two and then to three. For most of the PPPs described above, an additional population that contained a single molecule of apoC-III in addition to apoA-I and/or apoA-II was detected. Upon composition analyses of individual subpopulations, LpA-I/A-II exhibited comparable proportions for total protein (∼58%), phospholipids (∼21%), total cholesterol (∼16%), triglycerides (∼5%), and free cholesterol (∼4%) across subfractions. LpA-I components, on the other hand, showed significant variability. This novel information about HDL subfractions will form a basis for an improved understanding of particle-specific functions of HDL.

Enamel Erosion in Dietary Acids: Inhibition by Food Proteins in vitro

The aim of this study was to investigate the effects of two common food proteins on human enamel erosion in vitro. Erosion was measured by non-contact profilometry in citric, malic and lactic acids at pH 2.8, 3.2 and 3.8 and five commercially available soft drinks, in the presence of a salivary pellicle. Whole milk casein or hen egg ovalbumin was added to the acid solutions and drinks at 0.2% w/v, and the effect on erosion was determined by comparison with the corresponding solution without protein. Casein significantly reduced erosion in all but two solutions. The effects of the individual subfractions of casein in citric acid at pH 3.2 were similar to that of whole casein. Ovalbumin reduced erosion in some solutions, but the magnitude of the reduction was less than that with casein. A greater proportional reduction in erosion was seen in citric acid than in malic or lactic acids. We postulate that the mechanism involves adsorption of proteins to the pellicle or the enamel surface, forming a protein film with enhanced erosion-inhibiting properties. The citrate ion may play an active stabilising role, since erosion reduction was less in the other acids. In conclusion, casein and, to a lesser extent, ovalbumin show promise as potential anti-erosive additives to drinks.

NIR Hyperspectral Imaging Methods for Quality and Safety Control of Food and Feed Products: Contributions to Four European Projects

IR hyperspectral imaging instruments have significant advantages and are becoming the technique of choice for the analyst seeking to solve specific analytical problems. The addition of the spatial di mension to the frequency and absorbance dimensions opens the door to easy collec tion of thousands of spectra from one sam ple; instead of having one spectrum per sample with which to determine a series of parameters, one has thousands of spectra of sub-fractions of the samples on which one can individually determine parameters of interest in order to make some conclu sions about the individual sub-fractions or on the status of the entire sample. 1

Isolation of antioxidants from Psoralea corylifolia fruits using high-speed counter-current chromatography guided by thin layer chromatography-antioxidant autographic assay

A combinative method using high-speed counter-current chromatography (HSCCC) and thin layer chromatography (TLC) as an antioxidant autographic assay was developed to separate antioxidant components from the fruits of Psoralea corylifolia. Under the guidance of TLC bioautography, eight compounds including five flavonoids and three coumarins were successfully separated from the fruits of P. corylifolia by HSCCC with an optimized two-phase solvent system, n-hexane–ethyl acetate–methanol–water (1:1.1:1.3:1, v/v/v/v). The separation produced 5.91 mg psoralen, 6.26 mg isopsoralen, 3.19 mg psoralidin, 0.92 mg corylifol A, and 2.43 mg bavachinin with corresponding purities of 99.5, 99.8, 99.4, 96.4, and 99.0%, as well as three sub-fractions, in a single run from 250 mg ethyl acetate fraction of P. corylifolia extract. Following an additional clean-up step by preparative TLC, 0.4 mg 8-prenyldaidzein (purity 91.7%), 4.18 mg neobavaisoflavone (purity 97.4%) and 4.36 mg isobavachalcone (purity 96.8%) were separated from the three individual sub-fractions. The structures of the isolated compounds were identified by 1H NMR and 13C NMR. The results of antioxidant activity estimation by electron spin resonance (ESR) method showed that psoralidin was the most active antioxidant with an IC 50 value of 44.7 μM. This is the first report on simultaneous separation of eight compounds from P. corylifolia by HSCCC.

Spatio-temporal variability and principal components of the particle number size distribution in an urban atmosphere

Abstract. A correct description of fine (diameter &lt;1 μm) and ultrafine (&lt;0.1 μm) aerosol particles in urban areas is of interest for particle exposure assessment but also basic atmospheric research. We examined the spatio-temporal variability of atmospheric aerosol particles (size range 3–800 nm) using concurrent number size distribution measurements at a maximum of eight observation sites in and around Leipzig, a city in Central Europe. Two main experiments were conducted with different time span and number of observation sites (2 years at 3 sites; 1 month at 8 sites). A general observation was that the particle number size distribution varied in time and space in a complex fashion as a result of interaction between local and far-range sources, and the meteorological conditions. To identify statistically independent factors in the urban aerosol, different runs of principal component (PC) analysis were conducted encompassing aerosol, gas phase, and meteorological parameters from the multiple sites. Several of the resulting PCs, outstanding with respect to their temporal persistence and spatial coverage, could be associated with aerosol particle modes: a first accumulation mode ("droplet mode", 300–800 nm), considered to be the result of liquid phase processes and far-range transport; a second accumulation mode (centered around diameters 90–250 nm), considered to result from primary emissions as well as aging through condensation and coagulation; an Aitken mode (30–200 nm) linked to urban traffic emissions in addition to an urban and a rural Aitken mode; a nucleation mode (5–20 nm) linked to urban traffic emissions; nucleation modes (3–20 nm) linked to photochemically induced particle formation; an aged nucleation mode (10–50 nm). Additional PCs represented only local sources at a single site, or infrequent phenomena. In summary, the analysis of size distributions of high time and size resolution yielded a surprising wealth of statistical aerosol components occurring in the urban atmosphere over one single city. A paradigm on the behaviour of sub-μm urban aerosol particles is proposed, with recommendations how to efficiently monitor individual sub-fractions across an entire city.

Evidence That Heparin Saccharides Promote FGF2 Mitogenesis through Two Distinct Mechanisms

Heparin-like saccharides play an essential role in binding to both fibroblast growth factors (FGF) and their receptors at the cell surface. In this study we prepared a series of heparin oligosaccharides according to their size and sulfation level. We then investigated their affinity for FGF2 and their ability to support FGF2 mitogenesis of heparan sulfate-deficient cells expressing FGFR1c. Tetra- and hexasaccharides bound FGF2, but failed to dimerize the growth factor. Nevertheless, these saccharides promoted FGF2-mediated cell growth. Furthermore, whereas enzymatic removal of the non-reducing end 2-O-sulfate group had little effect on the 1:1 interaction with FGF2, it eliminated the mitogenic activity of these saccharides. This evidence supports the symmetric two-end model of ternary complex formation. In contrast, even at very low concentrations, octasaccharide and larger heparin fragments conferred a potent mitogenic activity that was independent of terminal 2-O-sulfation. This correlated with the ability to dimerize FGF2 in an apparently cooperative manner. This data suggests that potent mitogenic signaling results from heparin-mediated trans-dimerization of FGF2, consistent with the asymmetric model of ternary complex formation. We propose that, depending on saccharide structure, there are different architectures and modes of ternary complex assembly that differ in stability and/or efficiency of transmembrane signaling.

Influence of Alternative Liquid Chromatography Techniques on the Chemical Complexity and Bioactivity of Isolated Proanthocyanidin Mixtures

Extracts rich in proanthocyanidins, which are implicated in multiple human health benefits, were comparatively separated using alternative separation methods [vacuum or open column liquid chromatography], separation matrices [Toyopearl, Sephadex, or silica gel], and degrees of subfractionation [8 or 12 subfraction series], to evaluate the influence of separation technique on the resolution of the chemical composition and the biological activity of separated proanthocyanidin mixtures in individual subfractions. Bioactivity was assessed using a DNA human topoisomerase II bioassay and structural composition by acid thiolysis (average degree of polymerization, DP) and HPLC-ESI/MS. The amount of parent fraction needed to inhibit 50% of topoisomerase II was 3.38 ng/mL with an average DP of 25.5. A 2(3) factorial analysis revealed that the vacuum and open column strategies for separation, when individually considered, did not yield significantly different results in terms of mass recovery, DP, or bioactivity; however, interactions with other factors such as matrix or subfraction series resulted in distinctive shifts in fraction profiles and biological activity. In general, Sephadex as a matrix permitted elution and separation of discrete, polymerized subfractions with potent inhibition against human topoisomerase II. Sephadex vacuum chromatography, Toyopearl open column chromatography, and Toyopearl vacuum chromatography separation techniques eluted highly polymerized proanthocyanidin mixtures, but the inhibitory bioactivity was attenuated as compared to the parent fraction, whereas Sephadex open column chromatography eluted highly polymerized subfraction mixtures that retained bioactive potential.

Effect of ezetimibe monotherapy on the concentration of lipoprotein subfractions in patients with primary dyslipidaemia

ABSTRACTBackground: Recent studies suggest that the distribution of lipoprotein subfractions is an independent predictor of vascular events. Therefore, we evaluated the effect of ezetimibe (a selective cholesterol transport inhibitor) on the concentrations of lipoprotein subfractions in patients with primary dyslipidaemia.Materials and methods: Patients (n = 50) with primary dyslipidaemias were recruited. The concentrations of the individual lipoprotein subfractions were measured using the Lipoprint system at baseline and after 16 weeks of treatment.Results: Ezetimibe reduced total, low-density lipoprotein cholesterol (LDL‑C) and non-high-density lipoprotein cholesterol (HDL‑C) values as well as apolipoprotein B concentrations. Subfractionation of apolipoprotein B-containing lipoproteins showed that the reduction in LDL‑C values was due to a fall in the concentrations of all LDL subfractions. However, a more pronounced trend towards a decrease in the concen­trations of dense LDL subfractions was observed. Patients with triglyceride values >1.7 mmol/L had significantly greater reductions in the concentrations of small, dense LDL particles compared with those with normal triglyceride levels (49 vs. 19%, respectively; p < 0.05). Ezetimibe decreased the concentrations of HDL‑C mainly due to a fall in the concentration of dense HDL subfractions.Conclusion: Ezetimibe can favourably affect the distribution of LDL subfractions, especially in patients with elevated triglyceride values. Further studies are needed to clarify the significance of the ezetimibe-induced reduction in the concentrations of dense HDL particles.

Black Raspberry Extract and Fractions Contain Angiogenesis Inhibitors

Targeted therapies, such as agents that inhibit angiogenesis, offer hope as complementary agents in cancer therapy. Angiogenesis-inhibiting agents have the potential for inhibiting tumor growth and limiting the dissemination of metastasis, thus keeping cancers in a static growth state for prolonged periods. Black raspberry (Rubus occidentalis) extract was discovered to be antiangiogenic (0.1% w/v) in a novel human tissue-based in vitro fibrin clot angiogenesis assay. Assay-guided fractionation of a crude black raspberry extract resulted in a highly potent antiangiogenic fraction that accounted for only 1% of the fresh weight of whole black raspberries. At 0.075% (w/v), the active fraction completely inhibited angiogenic initiation and angiogenic vessel growth. Further subfractionation of this active fraction revealed the coexistence of multiple antiangiogenic compounds, one of which has been identified as gallic acid. However, the individual subfractions did not outperform the active whole fraction. These findings suggest that an active black raspberry fraction may be a promising complementary cancer therapy. It is natural and potent enough for manageable dosing regimens. These extracts contain multiple active ingredients that may be additive or synergistic in their antiangiogenic effects. These observations warrant further investigations in animals and human trials.

Pleiotropy and genotype by diet interaction in a baboon model for atherosclerosis: a multivariate quantitative genetic analysis of HDL subfractions in two dietary environments.

We investigated dietary effects on pleiotropic relationships among 3 HDL cholesterol (C) subfractions (HDL1-C, HDL2-C, and HDL3-C; levels quantified by gradient gel electrophoresis) for 942 pedigreed baboons (Papio hamadryas) who were fed a basal (Chow) diet and a high cholesterol, saturated fat (HCSF) challenge diet. Using multivariate maximum likelihood methods we estimated heritabilities for all 6 traits, genetic and environmental correlations (rhoG and rhoE) between them, and the additive genetic variance of each subfraction's response to the diets. On the Chow diet, genetic correlations between the 3 subfractions were significant, and we observed complete pleiotropy between HDL1-C and HDL3-C (rhoG=-0.81). On the HCSF diet, only the genetic correlation between HDL1-C and HDL3-C (rhoG=-0.61) was significant. Genetic correlations between individual subfractions on the Chow and HCSF diets did not differ significantly from 1.0, indicating that the same additive genes influenced each subfraction's levels regardless of diet. However, the additive genetic variance of response to the diets was highly significant for HDL1-C and HDL2-C, but not for HDL3-C. Similar sets of genes influence variation in the 3 HDL subfractions on the Chow diet, and the same set influences variation in each subfraction on the HCSF diet. However, the expression of genes influencing HDL1-C and HDL2-C is altered by the HCSF diet, disrupting the pleiotropy observed between the 3 subfractions on the Chow diet.

A bioassay-directed investigation of Sydney Harbour sediment

A coal tar-contaminated sediment sample from Sydney Harbour, Nova Scotia, Canada was examined for genotoxicity using a bioassay-directed fractionation approach. An organic solvent soluble fraction, prepared from the marine sediment by ultrasonic extraction, was fractionated into compound classes using a sequential alumina and Sephadex LH20 clean-up procedure followed by high performance chromatographic techniques. The PAH-containing fractions were analyzed using gas chromatography-mass spectrometry (GC-MS) and reversed phase-high performance liquid chromatography (RP-HPLC). The composition of the fractionated material was also characterized using Salmonella typhimurium microbiological assays to identify fractions with mutagenic potency. The fraction containing the PAH was the major source of mutagenicity requiring microsomal activation. Compounds responsible for some of the mutagenic activity in the PAH-containing fraction, including benzo[a]pyrene, benzo[ghi]perylene and indeno[1,2,3-cd]pyrene, were identified through a combination of RP-HPLC followed by GC-MS of individual subfractions.

Cholinergic synapses of the associative temporal area of the neocortex in the realization of cognitive functions.

The activity of choline acetyltransferase in the subsynaptic fractions of light and heavy synaptosomes of the associative temporal areas of the neocortex of cats with varying capacities for the formation of preverbal concepts was investigated. With respect to the majority of the subfractions, differences were detected between animals with normal and decreased intellect. Some theoretical conclusions were drawn relative to the origin of the individual subfractions; the role of cholinergic synapses of the area in question in the realization of the function of generalization and abstraction is discussed.

Electrophoretic Analysis of Ruminal Degradability of Corn Proteins

Albumin, globulin, and prolamin fractions were extracted from corn meal in water, .5 M NaCl, and 50% (vol/vol) 1-propanol and examined by SDS-PAGE and densitometric scanning to investigate fractional degradation rates of corn proteins. Several protein fractions were identified for globulins, zein prolamins, and glutelins. Ruminal degradability of individual subfractions was evaluated by suspension of corn and corn gluten meal samples in the rumen of lactating dairy cows from 0 to 72h. Electrophoretic and densitometric analysis of protein residues revealed that the prolamin fraction zein for corn and corn gluten meal was more resistant to ruminal degradation than albumins, globulins, and glutelins. Relative rates of degradation of zein and the fraction containing albumins, globulins, and glutelins were .060, .026, and .018, .015/h for corn and corn gluten meal, respectively. Total degradabilities of corn and corn gluten meal, measured by summation of degradability of subfractional components, were 52.2 and 18.6%. Quantitative measurement of ruminally degradable subfractions and estimation of their degradation rates by electrophoretic and densitometric scanning are useful in understanding ruminal degradability of corn proteins.

Structures of sulfated oligosaccharides in human trachea mucin glycoproteins.

The structures of high molecular weight sulfated oligosaccharide chains in mucins purified from the sputum of a patient with cystic fibrosis and blood group H determinant were established. Reduced oligosaccharides released by treatment with alkaline borohydride were separated by ion exchange chromatography on DEAE-Agarose and a fraction containing multisulfated chains was further purified by lectin affinity chromatography to completely remove small amounts of sialylated chains. A major sulfated oligosaccharide fraction containing chains with an average of 160 to 200 sugar residues was isolated by gel filtration on BioGel P-10 columns and individual subfractions were characterized by methylation analysis, periodate oxidation and sequential glycosidase digestion before and after desulfation. Carbohydrate analysis yielded Fuc, Gal and GldNAc in a ratio of 1:2:2.1 and only one galactosaminitol residue for every 160- to 200 sugar residues. The average molecular weight of oligosaccharide chains in these fractions was between 27,000 and 40,000 daltons. Structural analysis showed that these high molecular weight chains contained varying amounts of the repeating unit shown in the following oligosaccharide. Only one in about every 10 repeating units contained sulfate esters. Several shorter chains which contain 2 to 3 sulfate esters were also isolated from this multisulfated oligosaccharide fraction. The structures proposed for these oligosaccharides indicate that they are lower molecular weight chains with the same general structure as those found in the high molecular weight sulfated oligosaccharides. Taken collectively, the results of these studies show that a major sulfated oligosaccharide fraction in respiratory mucin purified from the mucus of patients with cystic fibrosis contains high molecular weight branched chains that consist of a repeating oligosaccharide sequence with sulfate linked to the 6 positions of galactose and possibly GlcNAc residues in the side chains.

The mapping of three subfractions of endoplasmic reticulum membranes isolated from L-929 cells by the use of spin probes.

This paper concerns the estimation of microviscosity parameters in smooth, light rough and heavy rough endoplasmic reticulum subfractions isolated from L-929 cells. Electron spin resonance using three probes was utilized in order to make estimations of rotational correlation times. The highest microviscosity was found in the smooth fraction. The lipid bilayer is less viscous and the annular one more rigid in heavy rough compared to light rough membranes. The individual membrane subfractions differ with regard to their 'portrait' of thermoinduced structural transitions. The highest number of such transitions was detected in smooth membranes. There were no low-temperature transitions (relative to physiological temperature) or common thermoinduced structural rearrangements of the lipids in the heavy rough subfraction, a membrane fraction characteristic of transformed cells. The results show that each membrane subfraction is characterized by an intrinsic series of thermoinduced structural transitions, which, in combination with an estimation of microviscosity, yields a 'portrait' of the structural state of the membrane lipids.

Alterations in plasma lipoproteins and apolipoproteins associated with estrogen-induced hyperlipidemia in the laying hen.

The laying hen represents a physiological model in which the mechanisms of action of estrogens on lipid transport can be evaluated. The plasma lipoproteins in the laying hen were subfractionated into discrete particle species by isopycnic density gradient ultracentrifugation and the physicochemical properties and apolipoprotein contents of individual subfractions evaluated. The qualitative and quantitative aspects of this estrogen-specific profile were then compared to those of the immature chicken. As observed earlier, estrogens induced dramatic elevation in very-low-density lipoproteins (VLDL) (up to 900 mg/dl). Indeed, triglyceride-rich lipoproteins with densities up to 1.035 g/ml, i.e. VLDL and their remnants, behaved as a continuum which displayed little variation in size (20.5-21 nm), electrophoretic mobility (beta-like) and apolipoprotein content; apo B-100 (540 kDa) predominated while apo A-I (27 kDa), apo VLDL-II (19 kDa) and an apo-C-like protein (13 kDa) were present as minor components. The typical high-density lipoproteins (HDL) in the immature chicken were replaced by a lipoprotein population whose physicochemical properties were quite distinct. Thus these particles were distributed as a single, asymmetric peak over the density range 1.030-1.158 g/ml, a wide interval which overlapped that of apo-B-rich particles at its lower limit. The rho 1.030-1.158 g/ml lipoproteins were present at concentrations (approximately equal to 200 mg/dl) some twofold to threefold lower than those of HDL in immature birds. Furthermore, they displayed physical and chemical properties in common with both low-density lipoproteins (LDL) and HDL and were LDL-like in exhibiting beta mobility but HDL-like in size (9-15 nm diameter). Their protein moiety was also HDL-like in its predominant content of apo A-I; small amounts of apo VLDL-II and the apo-C-like protein were also detected. Substantial amounts of lipid were found at rho greater than 1.195 g/ml: such substances are absent in the immature chicken and may reflect the presence of vitellogenins. The hyperestrogenic state in the laying hen is therefore associated with major modifications in lipoprotein and apolipoprotein profile. Such modifications may be of relevance to clinical disorders involving estrogen-induced hyperlipidemia.