International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Standardization Project for the Measurement of Lipoprotein(a). Phase 2: selection and properties of a proposed secondary reference material for lipoprotein(a).

The International Federation of Clinical Chemistry and Laboratory Medicine Working Group for the Standardization of Lipoprotein(a) Assays has initiated a project to select a secondary reference material for lipoprotein(a) that can standardize the measurement of this lipoprotein. Most of the analytical problems with lipoprotein(a) assays are due to apolipoprotein(a) kringle 4 type 2 reactive antibodies and values being expressed in mg/l mass units rather than as nmol/l of apolipoprotein(a) particles. In Phase 2, four manufactured materials were compared for analytical performance, commutability properties and method harmonization in 27 lipoprotein(a) test systems.

Semi-automated rapid isoelectric focusing of apolipoproteins C from human plasma using Phastsystem and immunofixation.

Apolipoproteins (apo) C-I, C-II, and C-III play crucial roles in intravascular lipid metabolism. Whereas apo C-II is an obligate cofactor for lipoprotein lipase, apo C-III was shown to inhibit its action. Apo C-I can be a potent cofactor of human lecithin:cholesterol acyltransferase.

Modulation of apo A-IV transcript levels and synthesis by n-3, n-6, and n-9 fatty acids in CACO-2 cells.

It has been postulated that apolipoprotein (apo) A-IV plays various significant roles in lipid transport and lipoprotein metabolism. Although it is controlled by fat feeding, so far little else is known about its regulation by specific fatty acids. In this study, we focused on the modulation of apo A-IV mRNA levels, mass, and biogenesis by mono- and polyunsaturated fatty acids (FA) in the human intestinal Caco-2 cell line.

Metabolic basis of high density lipoproteins and apolipoprotein A-I increase by HMG-CoA reductase inhibition in healthy subjects and a patient with coronary artery disease.

HMG-CoA reductase inhibitors, such as pravastatin, are widely used as lipid lowering drugs in hypercholesterolemia. Pravastatin does not only reduce the atherogenic low density lipoprotein (LDL)-cholesterol, but is also increasing high density lipoprotein (HDL)-cholesterol. However, the mechanism leading to an increase of HDL are unclear.

Lifibrol enhances the low density lipoprotein apolipoprotein B-100 turnover in patients with hypercholesterolemia and mixed hyperlipidemia.

Lifibrol (4-(4'-tert-butylphenyl)-1-(4'carboxyphenoxy)-2-butanol), a new hypocholesterolemic drug, effectively reduces total cholesterol (CH), low density lipoprotein (LDL)-CH, and apolipoprotein (apo) B in experimental animals and in humans. The impact of Lifibrol on the metabolism of apoB-100 containing lipoproteins in patients with hyperlipoproteinemia using endogenous labeling with stable isotopes is examined. Kinetic studies were performed in four male hypercholesterolemic individuals (type IIa) before and on treatment with 450 mg of Lifibrol daily for 4 weeks, and in five male individuals suffering from mixed hyperlipidemia (type IIb) before and on therapy for 12 weeks.

Effects of a frequent apolipoprotein E isoform, ApoE4Freiburg (Leu28-->Pro), on lipoproteins and the prevalence of coronary artery disease in whites.

Different isoforms of apoE modulate the concentrations of plasma lipoproteins and the risk for atherosclerosis. A novel apoE isoform, apoE4Freiburg, was detected in plasma by isoelectric focusing because its isoelectric point is slightly more acidic than that of apoE4. ApoE4Freiburg results from a base exchange in the APOE4 gene that causes the replacement of a leucine by a proline at position 28.

Distribution of cerebral flow using retrograde versus antegrade cerebral perfusion.

Background: This study compared flow to the brain with retrograde and antegrade cerebral perfusion during circulatory arrest.

Methods: Twenty-four rabbits were injected with 5 mCi of technetium-99 macroaggregated albumin, a tracer trapped in the capillaries. Group I (n = 6) were maintained normothermic, and the tracer was injected into the ascending aorta.

[Laboratory diagnosis in preventive cardiology].

In recent years a large number of coronary artery disease risk factors were discovered. The knowledge of these factors improves the estimate of the coronary artery disease (CAD) risk--however it still remains to be only an "estimate". A perfect prediction of an upcoming CAD event is not possible, despite all high score laboratory technology.

[Lipid lowering therapy for primary prevention of coronary heart disease--pro lipid lowering therapy].

The high rate of coronary artery disease (CAD) mortality needs preventive intervention. Several studies have documented the effectiveness of LDL-cholesterol lowering in CAD primary prevention. The West of Scotland Prevention Study resulted in risk reduction by about one third through LDL-cholesterol lowering.

Chymase gene locus is not associated with myocardial infarction and is not linked to heart size or blood pressure.

The chymase gene is said to be important for the generation of angiotensin II in the heart and therefore is a candidate gene for heart disease. However, we were unable to find an association between allelic variants of the chymase gene and acute myocardial infarction or linkage between the chymase gene locus and heart size.

Isoforms of murine and human serum amyloid P component.

Isoelectric focusing (IEF) and immunofixation of murine serum amyloid P component (SAP), purified and in serum, showed a distinct and strain-dependent isoform pattern with up to seven bands (pI 5.1-5.7).

Renal depth estimates to improve the accuracy of glomerular filtration rate.

Unlabelled: This study was performed to validate a computer implementation of the Gates' method for radionuclide glomerular filtration rate (RGFR) calculation. The accuracy of the original method was improved by replacing the Tonnesen formula that estimated renal depth with direct measurement from lateral views to calculate tissue attenuation correction.

Methods: Both the creatinine clearance test (CCT) and dynamic 99mTc-diethylenetriamine pentaacetic acid (DTPA) renal scintigraphy (DRS) were performed on 38 patients on the same day.

International Federation of Clinical Chemistry standardization project for the measurement of lipoprotein(a). Phase I. Evaluation of the analytical performance of lipoprotein(a) assay systems and commercial calibrators.

A secondary reference material for lipoprotein(a) is required to standardize the measurement of lipoprotein(a) in clinical laboratories worldwide. Towards this aim, the International Federation of Clinical Chemistry Working Group for the Standardization of Lipoprotein(a) Assays has initiated a standardization project involving a total of 33 diagnostic company and clinical chemistry laboratories from 12 countries. In Phase 1, the analytical performance of 40 lipoprotein(a) assay systems was evaluated by testing sera and manufactured lipoprotein(a) calibrator materials for precision, linearity, and parallelism.

Expression and conservation of apolipoprotein AIV in an avian species.

In birds, intestinally derived lipoproteins are thought to be secreted directly into the portal vein rather than to enter the circulation via the lymphatic system as in mammals. Hepatic clearance of these so-called portomicrons must be rapid, but the protein(s) mediating their catabolism, presumably analogues of the 36-kDa mammalian apolipoprotein E, have not been identified. In searching for such a mediator(s), we have isolated a hitherto unknown 38-kDa protein from chicken serum, which we identified by microsequencing and molecular cloning as a counterpart to mammalian apolipoprotein AIV (apoAIV).

European Lipoprotein Club: report of the 20th annual conference, Tutzing, 8-11 September 1997.

The year 1997 celebrated the 20th anniversary of the European Lipoprotein Club. Sessions explored topics in the line of classical concepts and forthcoming advances in the field of basic and clinical research on lipoproteins. Participants from 18 European countries attended the conference.

Standardization of Lp(a) measurements.

The standardization of immunoassays for Lp(a) is a major challenge to clinical chemists. In order to establish a reference material acknowledged by the International Federation of Clinical Chemistry, the Center of Disease Control and possibly the World Health Organization, a working group with participants from four continents was put together. With the aid of 34 companies, eight proposed reference materials have been tested in the last 3 years and two of them have been selected for value assignment.

Serum amyloid A (SAA) protein enhances formation of cyclooxygenase metabolites of activated human monocytes.

As serum amyloid A (SAA), an apolipoprotein associated with HDL during the acute-phase reaction may induce Ca2+ mobilization in human monocytes we raised the question whether SAA1 the predominant isoform of human acute-phase SAA is able to alter eicosanoid formation. In resting monocytes SAA1 was without effect on the secretion of cyclooxygenase metabolites while in calcium ionophore A23187- (0.5 and 2.

Splenogonadal fusion diagnosed by spleen scintigraphy.

Splenogonadal fusion (SGF) is a rare congenital malformation characterized by fusion of the spleen and a gonad (almost always the left one) frequently associated with orofacial and/or limb developmental abnormalities. Only 125 cases were reported between 1883 and 1994. This report concerns a case of SGF in a 20-yr-old woman with an accidental finding of a splenic space-occupying lesion protruding into the lower abdomen in ultrasound and CT.

Anterior operculum syndrome localized by SPECT.

Unlabelled: The aim of this case report was to present a patient with complete anarthria and orofacial apraxia without other relevant neurological deficit. The clinical features are compatible with anterior operculum syndrome.

Methods: A regional brain perfusion scan was done using 99mTc-HMPAO and a SPECT gamma camera.

Homozygous familial defective apolipoprotein B-100. Enhanced removal of apolipoprotein E-containing VLDLs and decreased production of LDLs.

Familial defective apolipoprotein B-100 (FDB) is a frequently inherited disorder of lipoprotein metabolism. The glutamine-for-arginine substitution at position 3500 of apolipoprotein (apo) B-100 leads to defective binding of apo B-100 to the low density lipoprotein (LDL) receptor and accumulation of LDL in the plasma. We recently identified a patient homozygous for this mutation.

[Effects of lipid lowering measures on coronary perfusion].

Secondary intervention trials in coronary heart disease have unequivocally proven the effectiveness of lipid-lowering medication in addition to dietary means. Orderly application of available drugs leads to reductions in LDL cholesterol and triglycerides accompanied by increases in HDL cholesterol. Specifically, LDL cholesterol lowering is associated with clinical benefits in coronary heart disease, it reduces the necessity of hospitalization and interventions, and leads to significant reductions in coronary as well as in overall mortality.

Lipoprotein(a) in health and disease.

Lipoprotein(a) [Lp(a)] represents an LDL-like particle to which the Lp(a)-specific apolipoprotein(a) is linked via a disulfide bridge. It has gained considerable interest as a genetically determined risk factor for atherosclerotic vascular disease. Several studies have described a correlation between elevated Lp(a) plasma levels and coronary heart disease, stroke, and peripheral atherosclerosis.

Polymorphisms of apolipoproteins A-IV and E in a Turkish population living in Germany.

Human apolipoproteins (apo) E and apo A-IV are polymorphic with significantly different allele frequencies among different ethnic groups. Whereas the variation at the apo E gene locus affects plasma cholesterol levels in all populations studied so far and is associated with longevity in Caucasians, the influence of the common apo A-IV polymorphism on plasma lipoproteins has not been unanimously accepted. We have therefore determined the common apo E and apo A-IV polymorphisms by isoelectric focusing, calculated the respective allele frequencies and studied their effects on plasma lipoproteins in a random sample of 240 nonrelated Turkish subjects (141 males, 99 females) living in Germany and originating from central and eastern Anatolia.