Comparison of hydrophobic properties of thoracic duct lymph chylomicrons from rats given different fats or oils by gavage.

Lipoprotein aggregation is generated by hydrophobic nature of lipoproteins that is known to be one of the causes of atherosclerosis. Low density lipoproteins (LDL) has been extensively studied in this respect but not chylomicrons. There is strong evidence that post-prandial triacylglycerol-rich lipoproteins are atherogenic. Because biophysical properties of lipoproteins are largely determined by their lipid compositions, hydrophobic nature of thoracic lymph duct chylomicrons obtained from rats given different fats or oils by gavage was investigated by vortexing-induced aggregation and hydrophobic interaction chromatography. Contrary to LDL, vortexing did not cause aggregation in chylomicrons. Vortexing of fish oil and butter chylomicrons resulted in more prominent reduction in absorbances compared with chylomicrons from other sources that might indicate less micelle stability. Hydrophobic interaction chromatography of fish oil, palm oil and olive oil chylomicrons yielded three fractions, whereas that of sunflower, margarine and butter chylomicrons gave rise to two fractions. These results suggest that surface hydrophobicity of chylomicrons might be heterogenous. Our results also demonstrate that fish oil chylomicrons have less hydrophobicity and lower stability against vortexing compared with chylomicrons from other sources. Considering beneficial effects of fish oil in cardiovascular health, less hydrophobicity together with lower stability might provide an additional atherogeneicity index for lipoproteins.

Investigation of age, sex and menstrual stage variation in human cerumen lipid composition by high performance thin layer chromatography.

OBJECTIVE: The objective of the study was to correlate quantitative changes in the lipid composition of human cerumen with changes in age, sex and menstrual cycle stage. DESIGN: Cerumen samples were collected from the external ear canal and analysed using sequential, one dimensional, high performance thin layer chromatography. SUBJECTS: The following age groups of both sexes were investigated: one to 10 years; 11-18 years; 19-40 years; and 40 years and over. Additionally, cerumen samples from subjects in three stages of the menstrual cycle were compared. RESULTS: In the cerumen samples, the peak values for wax ester and cholesterol occured between the ages of one and 10 years for both sexes. However, squalene and triglyceride content reached maximum levels at puberty. Men aged 19-40 years had a significantly greater percentage of cerumen lipid squalene content than women from the same age group; however, their cholesterol content was found to be lower. Regarding the various menstrual cycle stages, cerumen samples taken at the follicular stage from women aged 19-40 years had a significantly lower free fatty acids content, and higher cholesterol and squalene levels, compared with samples taken in the luteal or menstrual stages. CONCLUSION: The proportions of the lipid constituents of cerumen varied with age, sex and menstrual stage. In cerumen, the main lipid constituent stimulated at puberty appears to be squalene, not wax esters as reported for sebum. The relevance of lipid constituents to cerumen's protective role is discussed.

Investigation of lectin activity in Theileria annulata piroplasms.

Adhesion to target cells is an essential step in the pathogenesis of many protozoal infections. Some protozoa have been reported to have a lectin activity involved in their attachment to the cell surface. The ligand-receptor interaction involved in Theileria annulata infection is unclear at present, in spite of the fact that some aspects of the process have been investigated. To this end, T. annulata piroplasms have been screened for lectin activity. Blood taken from infected cattle was first depleted of leukocytes and then subjected to ammonium chloride lysis in order to isolate the piroplasms. The piroplasms were homogenised and a crude membrane extract was prepared by centrifugation. To investigate lectin activity in piroplasm proteins, a simple screening procedure was employed for analysing piroplasm proteins binding to various lectin ligands. Numerous immobilised lectin ligands (L-fucose-sepharose, N-acetyl-neuraminic acid-sepharose, N-acetyl-D-galactosamine-agarose, N-acetyl-D-glucosamine-agarose, D-mannose-agarose, beta-D-glucose-agarose, alpha-methyl-D-mannoside-agarose) were incubated with T. annulata piroplasm crude membrane extract. The ligand-bound proteins were eluted and separated by a brief centrifugation and determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). The present study suggests that a 32 kDa protein of piroplasm binds to D-galactosyl residues of the agarose matrix and that the binding is inhibited by galactose and not by the other monosaccharides tested.

The determination of diethylstilbestrol (DES) in the faeces and tissues of chickens treated with DES and in the faeces and tissue samples of calves, lambs and chickens collected from various areas of Turkey.

Diethylstilbestrol (DES) analyses were carried out on muscle, liver, kidney and faeces samples of 20 control and 20 experimental broilers to which 5 mg DES/day had been given orally for a period of 7 days. The treated samples were analysed using the Radioimmunoassay method. The removal time of DES from the tissues was determined. Five days following the final administration of DES, its faecal concentration was 151 ppb. However, 7 days after the final administration faecal DES concentrations increased again. On the first day after the final DES administration, DES concentrations in the liver, muscle and kidney were 0.78, 0.74 and 1.33 ppb, respectively. While these values measured on the final day were within the range of the control values. There was an increase of DES in plasma at the end of the experimental period. A total of 1811 muscle, liver, kidney and faeces samples of calves, lambs and chickens and feed samples collected from various areas in Turkey were analysed for the presence of DES. Positive samples for chicken feed was 36.9%. Also 1.9% of the chicken faeces samples were DES positive. All other samples were negative for DES.

Hepatic uptake and processing of cholesterol and cholesteryl ester from chylomicron remnants: an in vivo study in the rat.

The metabolic fate of cholesterol in chylomicron remnants was studied after intravenous infusion into biliary drained rats. The remnants were radiolabelled with [3H]cholesterol in vivo, so that radioactivity was incorporated into both the unesterified (27% of label) and esterified (73% of label) cholesterol fractions, or with 14C-labelled unesterified cholesterol after exchange in vitro. Blood and bile samples were collected at intervals for 180 min, after which the animals were killed for analysis. The total amount of radioactivity found in the liver (46%) and bile (4.5%) after infusion of [3H] remnants was higher than that found when the label was 14C (33 and 2.7%, respectively). Radioactivity from 14C-labelled unesterified cholesterol was cleared more rapidly from the blood, but the distribution of the label between the lipoprotein fractions VLDL + LDL, HDL2 and HDL3 at the end of the experiment was similar to that found when total [3H]cholesterol was used. In experiments with both types of label, approximately 94% of the total radioactivity secreted into bile was associated with the bile acid, with only about 6% in biliary unesterified cholesterol, and these proportions did not change during 180 min. When the chylomicron remnants were labelled with total [3H]cholesterol the specific radioactivity of the bile acid, taurochenodeoxycholic acid, in the bile was approximately twice that observed when the label was unesterified [14C]cholesterol. The specific radioactivity of unesterified biliary cholesterol was very low in the latter case, but higher and more comparable to that of taurochenodeoxycholic acid in the former. Thus, the metabolic fate of chylomicron remnant cholesterol differs, depending on whether it is in the esterified or unesterified form, suggesting that hepatic cholesterol originating from the two fractions may mix to a different extent with the various intracellular pools. In addition, the experiments with 14C indicate that the behaviour of chylomicron remnant unesterified cholesterol resembles that exhibited by cholesterol in HDL more than that carried in VLDL or LDL.