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A very strong association between phenotype Lp(a +) and presence of pre-β1-lipoprotein has been observed in two series of healthy young adults. The data are in agreement with the view that pre-β1-lipoprotein is identical to the lipoprotein carrying the Lp(a) antigen: the Lp(a) lipoprotein. Lp(a) antigen/pre-β1-lipoprotein occurred more frequently in persons with a positive than with a negative family history of coronary heart disease, though this trend was not statistically significant. Occurrence of Lp(a) antigen/pre-β1-rlipoprotein was not correlated with smoking or with the use of contraceptive pills.

Previous studies have shown that a slow-moving pre-beta-lipoprotein fraction, named the pre-beta1-lipoprotein, occurred significantly more frequently among subjects with coronary heart disease (CHD) than among healthy individuals. This lipoprotein is closely related to, and probably identical with, the Lp(a) lipoprotein. Immunological tests likewise showed that Lp(a) lipoprotein was significantly more common among patients with CHD than among controls. Mean cholesterol and triglyceride levels were higher in pre-beta1-lipoprotein positive than in pre-beta1-lipoprotein negative individuals. Lp(a+) individuals tended to have higher serum cholesterol values than did Lp(a-) persons but there was no difference in the mean triglyceride value. This apparent discrepancy seems to be due to the presence in occasional sera of lipoprotein fractions with pre-beta1-mobility, usually of a VLDL nature. These lipoproteins are not associated with the Lp(a) lipoprotein.

Summary This paper presents evidence of five isoimmune sera, which identified five antigens of cattle blood serum. These antigens were examined by means of staining, immuno-electrophoresis and Sephadex G 200 column chromatography. It was established that the BA-2, BA-3, BA-4 and BA-4′ antigens were proteins, whilst the BA-1 antigen was a lipoprotein. The BA-3 antigen migrated in the γ-globulin position; the remaining four antigens migrated in the α-globulin region. The antigens under examination were already present in the blood serum during the first few days of life and appeared to be of a stable character. The results of genetic analysis suggest that these antigens were transmitted according to Mendelism.

A small number of recent studies have reportedly failed to detect the well-established association between a high Lp(a) lipoprotein level and coronary heart disease (CHD). This has made some workers question the importance of a high Lp(a) lipoprotein level as a CHD risk factor. However, serious problems with some of the commercially available test kits, inadequate test techniques or failure to consider the lability of the Lp(a) lipoprotein particle are more plausible explanations of the confounding results. The problems with some of the commercially available test kits include lack of standardization and validation; risk of cross-reactivity with plasminogen or other serum proteins; failure to consider potential problems when measuring samples with varying length of the Lp(a) polypeptide chain (i.e. failure to cope with the isoform variation); non-divulgence of contents of test reagents; and pretreatments of samples that drastically change the Lp(a) lipoprotein particles from their native state. Any test system should be validated at the scientific level before it is assumed to provide correct measurements of Lp(a) lipoprotein level in serum. New test kits should be safely anchored in validation in one of the research laboratories active in the area, before they are put on the market. As new batches are produced, the quality of every new batch of test kits should be monitored on a long-term basis in collaboration with a research laboratory.

The effects of cholesterol on droplet size distribution and rheological properties of cholesterol-reduced egg yolk-stabilized emulsions were determined. Oil-in-water emulsions were prepared by using spray-dried eggs submitted to different levels of cholesterol reduction (14–81 wt% of cholesterol removed). Cholesterol was extracted in a modified Jennings apparatus with subcritical CO2 (9°C and 4.66·106 Pa). Oscillatory and steady flow tests, as well as droplet size distribution measurements, were carried out on the cholesterol-reduced egg yolk-stabilized emulsions. The rheological parameters increased with the level of cholesterol reduction up to 40–80 wt% for emulsions having the same total amount of egg yolk. Opposite results, however, were obtined with some emulsions stabilized by a highly cholesterol-reduced (≈80 wt%) egg yolk. These results were explained by taking into account two opposite phenomena: an increase in the concentration of surface-active agents as cholesterol content decreased, and a lipoprotein structural rearrangement induced by cholesterol removal.

In order to evaluate whether Lp(a), a lipoprotein that is potentially thrombogenic and atherogenic, is a potential risk factor for CAD in non-insulin-dependent diabetes (NIDDM), we compared the Lp(a) and its distribution in 145 NIDDM patients with that in 94 healthy control subjects. Furthermore, we studied the effect of insulin treatment on serum Lp(a) in 108 patients with NIDDM. Male and female NIDDM patients had similar Lp(a) concentrations to healthy controls (median value 167 mg L-1, range 15-1550 mg L-1 vs. 157 mg L-1, range 15-919 mg L-1, NS and 92, range 15-1190 mg L-1 vs. 103 mg L-1, range 15-842 mg L-1, NS). Also, the cumulative distribution of Lp(a) did not differ between the NIDDM patients and healthy subjects. Insulin treatment increased Lp(a) in diabetics with a Lp(a) concentration of less than 300 mg L-1, but this effect was not related to the concomitant improvement in metabolic control (mean change (+/- SEM) of HbA1c from 9.80 +/- 0.15 to 8.00 +/- 0.12; P0.001). In subjects with elevated Lp(a) concentrations (300 mg L-1) the Lp(a) concentration was unaffected by insulin, despite a similar improvement in glycaemic control. These results suggest that insulin may modulate the concentration of Lp(a).

Pulmonary surfactant is a lipoprotein complex produced by type II pneumocytes that lines and stabilizes alveoli. Surfactant-specific proteins are early markers of the embryonic lung. Precursors of type II pneumocytes appear to be committed early and are able to pursue their differentiation program in a relatively autonomous way. Despite this potential, surfactant ontogeny and storage actually take place relatively late in the course of fetal development. Surfactant accumulation is, therefore, delayed until a certain stage after which it is stimulated by a number of factors. Recent investigations have pointed out the possible role of paracrine mechanisms in the determinism of this control, especially with regard to retinoids and TGF-β. © 1995 Wiley-Liss, Inc.

Objective: Lp(a) lipoprotein is a distinct lipoprotein particle that recently has been found to be associated with cardiovascular disease. A study was conducted to assess the influence of cardiovascular disease risk factors on levels of Lp(a) and to evaluate the effects of age, exercise, and estrogen on these levels. Study Design: Two studies, a cross-sectional study of older men ( n = 105) and women ( n = 75) (mean age 76 years) and a prospective study of younger postmenopausal women (mean age 48 years), were carried out. Lp(a) and other lipoproteins were measured in the two studies and differences were sought by statistical analysis. Results: In the cross-sectional study, serum Lp(a) was similar in men and women and was not influenced by age. Lp(a) levels in men and women were higher when there was more than one cardiovascular disease risk factor present ( p p = 0.08). The decrease in Lp(a) with oral estrogen was associated with increases in triglycerides ( p p Conclusion: These data confirm that elevated Lp(a) levels are an independent risk factor for cardiovascular disease. Lp(a) levels are primarily influenced by genetic factors and it appears estrogen may have a minor influence on its hepatic synthesis.

Lp(a) lipoprotein is thought to be an addi- tional risk factor for coronary heart disease [l-3]. Papers published up to now have been concerned with its electrophoretical mobility [4,5], its chemical com- position [6,7] and its physiological role [l-3]. Con- cerning the size of the particle, only disagreeing information has been reported [8]. Serum concentra- tion of that lipoprotein differs from man to man, and Harvie and Schultz were the first to demonstrate that Lp(a) is expressed by a quantitative genetic trait [9,10]. A diet enriched by cholesterol did not influence the serum Lp(a) level, while LDL increased markedly [11,12]. As pointed out [13,14] Lp(a) reacts very sensitively on addition of Ca2+. The aim of this work was to provide for this lipo- protein the values for molecular weight (a,) diffu- sion coefficient (D), radius of gyration Cs;) and hydrodynamic radius

The partition of n-hexadecane in the spent growth medium of Acinetobacter sp. HOI-N was determined by measuring the increase in the relative aqueous solubility of 3H-hexadecane as compared to controls. The amount of hexadecane partitioned was proportional to the protein concentration. The specific solubility of hexadecane (nmol/mg protein) was analyzed by least-squares fitting yielding an average slope of 0.6 with a standard deviation of 0.3, indicating either nonequilibrium of hexadecane or physical aggregation of protein. The amount of hexadecane partitioned was concentration dependent yielding optically clear microemulsions at hexadecane concentrations of less than 1.4mM and macroemulsions at hexadecane concentrations of 1.4mM or greater. Preliminary results indicated that hexadecane and partitioned by a lipoprotein complex.

In cattle with J blood-group substance both on erythrocytes and dissolved in serum, J activity was found in the total lipids extracted from erythrocytes, but not in the proteins precipitated by lipid extraction and not in the mucoproteins prepared from erythrocytes. Serum from these animals, however, does not only exhibit J activity of its total lipid, but also of its mucoproteins and of its residue after lipid extraction. This serum, therefore, contains the J substance in at least two different forms, as a lipoprotein and as a mucoprotein. Only the J lipoprotein is able to coat bovine erythrocytes during a postnatal period. It is suggested that hydrophobic groups are responsible for the attachment of the J substance to the erythrocytes. In cattle with J substance only in serum, coating of erythrocytes is missing. This is apparently due to the finding that the serum from these animals contains J mucoproteins, but virtually no J lipoprotein. Since the determinant of the J lipoprotein has been found in the glycosphingolipid fraction the genetically fixed difference between animals which have J substance on erythrocytes and in serum and those which have it only in serum seems to consist in the inability of the latter animals to synthesize a glycosphingolipid containing the sequence of sugars which is responsible for J specificity.

Durch Subtraktion der Rontgenkleinwinkelstreuung gelber Blatter von der Rontgenkleinwinkelstreuung gruner Blatter kann die unspezifische Streuung der Blatter eliminiert und dadurch die spezifische Streuung des Lamellarsystems der Chloroplasten erhalten werden. Eine Analyse der spezifischen Streuung fuhrt auf eine Lipoproteinlamelle, die aus zwei Schichten, einer Lipid- und einer Proteinschicht, aufgebaut ist. Jeweils zwei derartige Lipoproteinlamellen sind so angeordnet, das die beiden Lipidschichten benachbart verlaufen. Der Raum zwischen den beiden Lipidschichten ist mit Wasser ausgefullt. Die Abgrenzung der Lipid- gegen die Proteinschichten erfolgt durch die Porphyrinringe des Chlorophylls, die in einer monomolekularen Schicht angeordnet sind. Die Proteinschicht besteht aus einer zweidimensionalen Anordnung von Proteinmolekulen. By subtraction of the small angle X-ray scattering of yellow leaves from the small angle X-ray scattering of green leaves it is possible to eliminate the non-specific scattering of the leaves and to obtain thereby the specific scattering of the lamellar system of the chloroplast. The analysis of the specific scattering indicates a lipoprotein lamella which is built up by two layers, one lipid and one protein layer. Two lipoprotein lamellae are arranged in pairs so that the two lipid layers are neighbours. The space between the two lipid layers is filled by water. The boundary between the lipid and protein layers is formed by a monomolecular layer of the porphyrin rings of chlorophyll. The protein layer consists of a twodimensional arrangement of protein molecules.