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Lipoprotein (a) [Lp(a)] is a lipoprotein defined by presenting a specific apolipoprotein, ApoA, linked to the ApoB-100 by different types of chemical bonds, including a disulfide bridge. Despite their atherogenic mechanism is not fully understood, its importance has been demonstrated in the development of premature aterosclerosis. Multiple studies have shown its role as a cardiovascular risk factor associated with heart disease and stroke. We report the case of a patient with a diagnosis of Takayasu arteritis in which a massive elevation of Lp(a) was detected. We emphasize its diagnostic and therapeutic implications.

In high-risk patients who are already on a maximal lipid-lowering therapy, a lipoprotein apheresis is an important therapeutic option in preventing further progress of vascular complications as it may decrease both LDL-cholesterol (LDL-C) and lipoprotein(a) (Lp(a)) levels. We looked at the occurrence of cardiovascular events before apheresis and during apheresis in three groups defined by their lipid patterns at the start of an apheresis treatment: Group 1 (LDL-C ≥ 3.4 mmol/l and Lp(a) ≤ 600 mg/l; n = 35), Group 2 (LDL-C ≤ 3.4 mmol/l and Lp(a) ≥ 600 mg/l n = 37) and Group 3 (LDL-C ≥ 3.4 mmol/l and Lp(a) ≥ 600 mg/l; n = 15). Group 2 shows a time period of about 10 years from the first event until the start of apheresis treatment (compared to 2–6 years in the other two groups). Before the start of apheresis treatment 2.1 events per patient had occurred in Group 1, 3.4 events per patient in Group 2 and 1.8 events per patient in Group 3. Under apheresis therapy just 0.9 events per patient occurred in Group 1, 0.5 in Group 2 and 0.5 in Group 3. When comparing the two years before the start of apheresis treatment with the first two years under apheresis we saw the following reduction rates of cardiovascular events: Group 1–54%; Group 2–83%; Group 3–83.5%. Our results show that the reduction of cardiovascular events due to lipoprotein apheresis is especially high in patients with elevated levels of Lp(a) compared to patients with elevated LDL-C only indicating that physicians should be more focused on the risk factor elevated Lp(a).

Despite vitellins being essential yolk proteins, their presence in spiders remains almost unknown. Two vitellins from the spider Polybetes pythagoricus, named LV1 and LV2, were isolated and their size, shape, lipids, fatty acids, proteins and carbohydrates moieties were determined. LV1 has a density similar to that of HDL with 49.3% lipids, and LV2 has a density similar to that of VHDL with 9.7% lipids. The major neutral lipid present in both vitellins was found to be esterified cholesterol, 16% for LV1 and 24% for LV2. The major fatty acid was 18:1n-9 in LV1 and LV2. Results from native PAGE showed a lipoprotein of 550 kDa for LV1 and three lipoproteins of 571, 400 and 257 kDa for LV2. SDS-PAGE evidenced two major apolipoproteins of 64 and 25 kDa in LV1. The three lipoproteins of LV2 were electroeluted and analyzed by SDS-PAGE, showing different proportions of the same apolipoproteins (181, 67 and 60 kDa). LVs were analyzed by spectrophotometry, immunochemical and electron microscopy, showing that the respiratory pigment hemocyanin was not present as apolipoprotein. This fact evidenced that these LVs were not related to hemolymphatic lipoproteins.

To the Editor: Previous reports have demonstrated that lipoprotein-associated phospholipase A2 (Lp-PLA2), an enzymatic inflammatory biomarker, is associated with increased risk of cardiovascular events [(1)][1]. Lp-PLA2 mediates formation of bioactive mediators (lysophosphatidyl choline and

Background: The conformation and assembly of lipoproteins, proteins containing large amounts of noncovalently bound lipid, is poorly understood. Lipoproteins present an unusual challenge as they often contain varying loads of lipid and are not readily crystallized. Lipovitellin is a large crystallizable oocyte protein of approximately 1300 residues that contains about 16% w/w lipid. Lipovitellin contains two large domains that appear to be conserved in both microsomal triglyceride transfer protein and apolipoprotein B-100. To gain insight into the conformation of a lipoprotein and the potential modes of binding of both neutral and phospholipid, the crystal structure of lamprey lipovitellin has been determined. Results: We report here the refined crystal structure of lipovitellin at 2.8 a resolution. The structure contains 1129 amino acid residues located on five peptide chains, one 40-atom phosphatidylcholine, and one 13-atom hydrocarbon chain. The protein contains a funnel-shaped cavity formed primarily by two β sheets and lined predominantly by hydrophobic residues. Conclusions: Using the crystal structure as a template, a model for the bound lipid is proposed. The lipid-binding cavity is formed primarily by a single-thickness β -sheet structure which is stabilized by bound lipid. This cavity appears to be flexible, allowing lipid to be loaded or unloaded.

Lipoprotein (a) [Lp(a)] is a lipoprotein which has a plasma concentration that is highly correlated with cardiovascular disease. In this study, the new Lp(a) assay for the Vitek Immuno-Diagnostic Assay System (VIDAS) developed by bioMerieux was evaluated. This method uses an enzyme linked fluorescent immunoassay (ELFIA) technique. Within-run and between-run reproducibility of the Vidass Lp(a) assay are characterized by coefficients of variation (CV) of 3 to 5.9% and 3.9 to 5.9%, respectively. Using analysis of variance, no statistical difference was shown between ELFIA and immunonephelometric assay (INA). When comparing results of the Vidas Lp(a) test with the INA, a highly significant correlation of r = 0.9708 and regression line equation y = 0.963x-0.037 was found. Interference of lipemia was studied: no influence was observed up to 12.3 mmol l(-1) triglycerides. No interference of haemoglobin was noted for Lp(a) > 0.20 g l(-1). Hyperbilirubinemia ( > 120 micromol l(-1)) led to results being underestimated for concentrations of Lp(a) which were < 0.20 g l(-1). No pre-analytical interference of citrate was measured but pre-analytical interference of EDTA was found. In conclusion, this new fully automated immunofluorimetric Lp(a) assay enables to the rapid, accurate and reliable determination of Lp(a) in blood samples.

Among various taste stimuli, bitter substances are most abundant and their chemical structures are greatly diverse from each other. It has been known that there are multiple receptor sites and transduction mechanisms. Already in neonates, bitter stimuli elicit rejection responses, indicating strong negative hedonic tone. Bitter taste is decidedly unpleasant when the sensation is strong. The development of a method to mask bitterness has widely been required in pharmaceutical sciences and food sciences. To mask bitterness, a specific bitterness inhibitor would be most useful. Such an inhibitor would also be useful in elucidating the receptor mechanisms of bitter substances. No inhibitor has, however, been available. Recently we found that a lipoprotein, PA-LG made of phosphatidic acid (PA) and beta-lactoglobulin (beta-LG), selectively suppresses the taste responses to bitter substances. In this paper we describe the protocol used for inhibition of the frog taste (glossopharyngeal) nerve responses to bitter stimuli by the lipoprotein. The frog taste system is used because it is sensitive to various bitter substances and surgery of the animal for the electrophysiological recording is rather easy. We also describe the protocol used for inhibition of human taste sensation to bitter stimuli.

Summary The genetically determined Lp(a) lipoprotein whose specific apoprotein evolved from plasminogen exhibits association with atherosclerotic/thrombotic diseases including coronary heart disease (CHD). People with an Lp(a) lipoprotein concentration corresponding to the top quartile in the healthy population have a significantly increased CHD risk compared with those with a lower value, and the risk in the top decile appears to be particularly high. However, a very low Lp(a) lipoprotein level may also cause disadvantage with respect to CHD and longevity. Lp(a) lipoprotein may compromise thrombolytic processes through molecular mimicry and in vitro it stimulates vascular cells to cell division. The normal function of Lp(a) lipoprotein is unknown. It could be related to repair processes. Preliminary evidence suggests that Lp(a) lipoprotein may be involved in vascular processes in the placenta. It has been reported that Lp(a) lipoprotein increases following myocardial infarction in a way suggesting that it could possess characteristics of an acute phase reactant. In view of the strikingly high heritability of Lp(a) lipoprotein, this would a priori be unlikely. We have not been able to confirm a significant increase in Lp(a) lipoprotein following myocardial infarction. Several commercially available test kits are of a doudtful quality. At present, a highly needed, international effort at standardizing Lp(a) lipoprotein measurements is taking place.

We administered testosterone, with or without the aromatase inhibitor testolactone, to determine the effects of testosterone and its aromatization to estradiol on Lp(a) levels in normal men. Average Lp (a) values decreased by 37% during testosterone alone and by 28% when testosterone and testolactone were combined, suggesting that testosterone reduces Lp(a) in men primarily by an androgenic effect and not by its conversion to estradiol.

Two hundred and ninety four pairs of Swedish twins reared apart and twins reared together were used to evaluate the importance of genetic and environmental influences on lipoprotein(a) (Lp(a)) levels. Lp(a) levels ranged from10 mg/l to 926 mg/l with 7.9% of the sample having undetectable Lp(a) levels (i.e.10 mg/l). A substantial genetic component in Lp(a) variation was indicated by a heritability estimate of approximately 90%. No difference in heritability was found across age groups. Quantitative genetic analyses also suggest correlated environmental effects most likely composed of maternal, neonatal and postnatal environmental influences. However, these effects did not reach statistical significance, partly due to a lack of power. Results from analyses of co-twin differences in Lp(a) levels for monozygotic twins indicate that sex hormone use may be of importance for Lp(a) variation in women. There was no evidence of potential influences of alcohol consumption, beta-blocker and diuretic administration on Lp(a) levels in either men or women.

In a 3-year follow-up study of 761 elderly men and 983 elderly women, total plasma cholesterol levels predicted fatal coronary heart disease (CHD) in men but not women. Low-density lipoprotein level was no better a predictor of fatal CHD than total cholesterol in either sex. Women had higher levels of high-density lipoprotein than men, which explains most of their usual higher total cholesterol levels. These data suggest that cholesterol screening of elderly women would have little value without a lipoprotein evaluation.

As compared with what is known about predictors of vascular events in middle-aged persons, less is known about these events in the elderly. Lp(a) lipoprotein, which plays an important part in atherothrombogenesis, has been associated with an increased risk of vascular disease. We investigated this relation among older U.S. adults.In a prospective study of 5888 community-dwelling older adults (65 years of age or older) in the United States, 2375 women and 1597 men who were free of vascular disease provided base-line serum samples for analysis for levels of Lp(a) lipoprotein. These 3972 subjects were followed for a median of 7.4 years to evaluate the development of stroke and to track deaths from vascular causes and all causes. The men and women were divided into quintile groups according to the Lp(a) lipoprotein level at base line.Using Cox proportional-hazards models, we determined the risk associated with each quintile level of Lp(a) lipoprotein, with the lowest quintile serving as the reference group. As compared with those in the lowest quintile, men in the highest quintile had three times the unadjusted risk of stroke (relative risk, 3.00; 95 percent confidence interval, 1.59 to 5.65), almost three times the risk of death associated with vascular events (relative risk, 2.54; 95 percent confidence interval, 1.59 to 4.08), and nearly twice the risk of death from all causes (relative risk, 1.76; 95 percent confidence interval, 1.31 to 2.36). Adjustment for age; sex; the levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides; carotid-wall thickness; smoking status; the presence or absence of diabetes and systolic and diastolic hypertension; body-mass index; and other traditional risk factors had little effect on the final assessments. Similar analyses for women, which also included adjustment for estrogen use or nonuse, revealed no such relation.Among older adults in the United States, an elevated level of Lp(a) lipoprotein is an independent predictor of stroke, death from vascular disease, and death from any cause in men but not in women. These data support the use of Lp(a) lipoprotein levels in predicting the risk of these events in older men.

An estimated one-third of the world's population is infected with TB, and a vaccine that is effective in adults is urgently needed. Recently, the planned human trials for two potential vaccine have provoked controversy. Ian Orme, who screens TB vaccines for the US National Institutes of Health, has voiced concerns that the vaccine candidates are not ready for human testing. He is concerned that one of the vaccines – a DNA vaccine – could be dangerous if used in people with latent TB. However, Douglas Lowrie of the National Institute for Medical Research in London, the creator of the DNA vaccine, says that the vaccine has caused heavy TB infections to go into reverse in animal tests. Unrelated findings recently published in the Journal of Immunology might aid in the development of another vaccine. Researchers have identified a lipoprotein from MTB that interferes with antigen presentation to T cells. AV http://news.bmn.com/news/story?day=010727&story=1http://www.eurekalert.org/pub_releases/2001-07/cwru-rfh071301.php

1. 1. Lipoproteins staining with Sudan Black were isolated from the haemolymph of several desert arthropods. 2. 2. Millipedes and centipedes possess a lipoprotein structurally similar to insect lipophorin. 3. 3. Isopods utilize a different lipoprotein which is closely related to that of marine crustaceans. 4. 4. The haemolymph of most arachnids however contains lipophorin-like lipoproteins. 5. 5. With the exception of Crustacea, lipophorins seem to be universal throughout the phylum Arthropoda.

The amylose precipitating factor from Neurospora is a lipoprotein of 53,800 mw. The lipid component, which is responsible for the amylose precipitating activity, is mainly polar lipid and constitutes 14.5% of the lipoprotein molecule. The binding of amylose to the amylose precipitating factor possibly results in the conversion of the amylose molecule from a random coil to an interrupted helix configuration.

It is known that hypertriglyceridemia is associated with the elevation of plasma apolipoprotein CII (apoCII). In an attempt to look at the relationship between the two, the present study was conducted. We examined 30 patients with hypertriglyceridemia (TG, 210 to 9,127 mg/dL) and ten normolipidemic controls. Hypertriglyceridemic patients included 7 of type I hyperlipoproteinemia (HL), 17 of type IV, and 6 of type V. Plasma apoCII was measured by the single radial immunodiffusion method. Major cause for any difference in plasma apoCII could be attributed to differences in the TG-rich lipoproteins. Since a model for the lipoprotein structure indicates that TG-rich lipoproteins are spherical, with apoCII as a surface component and TG as a core substance, we calculated the square roots and the cubic roots of the values of apoCII and TG to make comparison possible. When the two variables were plotted on the X and Y axes respectively, we obtained the regression line of square root of apoCII = 0.37 X 3 the square root of TG - 0.03 with a correlation coefficient of r = .95 (P less than 0.001). The result indicates that a lipoprotein structural model accounts well for the relationship between apoCII and TG. Although a previous report suggested a compensatory increase of apoCII in lipoprotein lipase deficiency, our patients with type I HL had apoCII levels similar to those who had comparable levels of plasma TG.

Lipid studies were performed on fasting plasma samples in 214 healthy adolescent boys, 11-19 years of age. Ranges of normal values for plasma cholesterol and triglyceride concentrations, and normal lipoprotein patterns were established for this age group. The boys were grouped according to puberty rating. A significant increase in triglyceride values was obtained with adolescent maturity. Plasma cholesterol values did not change with age or puberty rating. One boy had hypercholesterolemia and a lipoprotein pattern consistent with Type II hyperlipoproteinemia (Fredrickson). Seventeen boys, all of whom had reached adolescent maturity, had elevated triglyceride values and a marked increase in pre-beta-lipoprotein. It appears from this study that increased concentrations of triglyceride and Type IV hyperlipoproteinemia of Fredrickson may be detected as boys reach maturity at adolescence.

Pig aorta glycerol ester hydrolase activity has been measured against a glyceryl tripalmitate hydrosol. The pattern of fatty acid release and the effect of some reagents known to modify lipase activity suggest that the glycerol ester hydrolase present in the pig aorta wall is a lipoprotein lipase.

Approximately half of the lipovitellin of stored shell eggs laid by hens fed a diet containing crude cottonseed oil was in a granule fraction which was not soluble in 0.7 M sodium acetate solution. The lipovitellins of this granule fraction were not isolated in the preparation of lipovitellin. The lipovitellins isolated from stored eggs contained slightly more β-lipovitellin than those isolated from fresh eggs. During storage of the eggs, some of the α-lipovitellin was converted to a lipoprotein which was eluted differently from an hydroxylapatite column than either α- or β-lipovitellin.

A rapid electrophoretic method detecting serum lipoprotein(a) (Lp(a)) was described. When serum lipoproteins were electrophoresed using an agarose gel film containing 0.6% agarose and 3% sucrose, a distinct extra-band was frequently detected between beta- and prebeta-bands. This lipoprotein band was identified as Lp(a) by immunoblotting technique using anti-Lp(a) serum. Using this electrophoretic method, we studied 1353 subjects with a variety of diseases. The Lp(a)-positive subjects accounted for 8.4% of all. Neither sex nor age influenced the frequency of Lp(a) positivity. Frequencies of definite myocardial infarction in Lp(a)-positive subjects did not differ significantly from those in Lp(a)-negative ones. Those of cerebral infarction in Lp(a)-positive subjects were significantly higher than those in Lp(a)-negative ones. An electrophoretic method described herein is very useful for the rapid detection and screening of Lp(a), and hence for large-scale clinical studies of atherosclerotic risk assessment.

An electrophoretic study of a lipoprotein from calf thymus and calf liver is presented. Each of the lipoproteins studied revealed the presence of only one component. Isoelectric points lie between pH 4.65 – 4.85.

SUMMARY Cow’s milk has been found to contain a lipoprotein lipase similar to those previously demonstrated in post-heparin plasma, adipose tissue, and heart. Upon separation of the milk, most of the enzyme was found in the skim milk, although some was present in the cream from which it could be isolated with a relatively high specific activity. The triglycerides of cream were not hydrolyzed by the lipoprotein lipase, and it is supposed that the enzyme does not function in milk but rather in the lactating mammary gland.

In order to identify the chemical nature of the membrane receptor sites involved in general anesthesia the apparent free energy of binding of methylene groups of n-alcohols in anesthetic systems was evaluated and compared with data from model systems. It was concluded that the sites may consist either of (i) the non-polar portions of lipids, (ii) a non-polar region of a lipoprotein made up of non-polar portions of the protein and lipid moieties or (iii) protein. However, if the site consists only of protein it is possible that this material undergoes a ligand-induced conformation change on binding the anesthetic. Some reasons for the use of caution in employing temperature effects to identify the chemical nature of the receptor sites are outlined.

A lipoprotein-X (LP-X) test has been performed in normal subjects and in patients with hepatobiliary diseases and haemolytic anaemia. Statistical analysis revealed a correlation between the occurrence of LP-X and increase of conjugated bilirubin and alkaline phosphatase. The LP-X test makes it possible to differentiate obstructive from non-obstructive jaundice but it fails to demonstrate or exclude cholestasis in all cases and cannot distinguish between intrahepatic and extrahepatic cholestasis.

Determination of the physicochemical parameters of a lipoprotein class from weight percentage data in light of a recent quantitative biodynamic concept which strictly adheres to the CGS unit system (cm, g, s) and the mass/volume chemical unit, mol·cm −3 .

Shell wastes from Snow crab contain about 33 mg% total astax-anthin, 28% protein, 28% chitin, 31% ash and 1% crude fat or a dry matter basis (dmb). Trypsin hydrolysis of shell waste, followed by precipitation of part of the solubilized material with ammonium sulfate, recovered 9% of the dry matter as a lipoprotein fraction. The fraction, called carotenoprotein, included 74% of the crude lipid, 66% of the astaxanthin and 22% of the protein originally present in the shell. The carotenoprotein product contained 239 mg% total astaxanthin, 65% protein (dmb) and was devoid of chitin. Carotenoprotein may find use as a dietary source of colorant and protein for cultured salmonids. Resume Les residus des coquilles de crabe Snow contiennent environ 33 mg% d'astaxanthine totale, 28% de proteine, 28% de chitine, 31% de cendres et 1% de graisse brute, sur une base seche (dmb). L'Hydrolyse a la trypsine du residu de coquille, suivie de la precipitation au sulfate d'ammonium d'une partie du materiel solubilise, a permis de recouvrer 9% de la matiere seche comme fraction lipoteique. La fraction, appelee carotenoproteine, renferma 74% des lipides bruts, 66% de l'astaxanthine et 22% des proteines originalement presents dans la coquille. Le produit carotenoproteine contenait 239 mg% d'astaxanthine totale, 65% de proteine (dmb) et etait libre de chitine. La carotenoproteine peut etre utilisee comme source dietetique de colorant et de proteine pour les salmonides cultives.

Serum lipoproteins have been separated using molecular exclusion or pore limit electrophoresis on acrylamide gel gradients. In a series of over 200 cases of coronary ischaemia, a lipoprotein component or components, intermediate in size between VLDL and LDL, have been found in 61% of cases. In approximately half of these it was the sole pattern anomaly present, while in the remainder increased VLDL or LDL were associated. The intensity of single midzone components (and the frequency of multiple components) were judged to be greater in the coronary series than in a control series.