Prevention of brain metastasis formation by local expression of interleukin-4 or hemagglutinin antigen

INTRODUCTION

Expression of hemagglutinin antigen of influenza virus (HA) by the murine colon carcinoma cell line (CT-26) produces systemic immunization against tumor challenges in the cecum, liver and lungs but not in the brain of BALB/c-mice. Immunization with IL-4 expressing CT-26 cells inhibits lung metastases formation. The purpose of our study was to examine the effects of HA or IL-4 expression on brain metastases formation.

METHODS

Using selective internal carotid artery injections, brain metastases formation of HA or IL-4 expressing CT-26 cells with and without subcutaneous pre-immunization was evaluated in Balb/c mice.

RESULTS

Systemic pre-immunization with HA or IL-4 expressing tumor cells cannot protect against brain metastases, while the local, intracerebral expression of HA or IL-4 inhibits the growth of hematogenous brain metastases.

CONCLUSION

Pre-immunization with HA or IL-4 expressing tumor cells did produce systemic immunity against liver and lung metastases but not against brain metastases. Local, intracerebral expression of HA or IL-4 prevents from cerebral metastases formation in an animal model.

Treatment of diabetic dyslipoproteinemia

Diabetes mellitus, specifically type 2, is often associated with disorders in lipid metabolism. Elevated levels of plasma free fatty acids play a pivotal role by contributing significantly to insulin resistance. In addition free fatty acids promote diabetic dyslipidemia through increasing VLDL synthesis in the liver, and by virtue of cholesterylester transfer protein, modifying LDL to increase small-dense LDL subfractions and to decrease HDL cholesterol. This atherogenic lipoprotein profile (elevated triglycerides, increased small-dense low-density lipoproteins, and decreased high-density lipoproteins), contributes to the development of atherosclerosis and increases the risk of experiencing cardiovascular events, the most common cause of death in type 2 diabetes. To decrease the risk of cardiovascular disease events in diabetics, dyslipidemia needs to be treated, as evidenced from epidemiology, from intervention trials, and from subgroup analyses of large intervention trials initiated to evaluate effects of lipid lowering treatment that also included patients with type 2 diabetes. Most measures used to counteract hyperglycemia, are also prone to ameliorate dyslipidemia: dietary intervention (medical nutrition) including omega-3 fatty acids as part of lifestyle changes that also comprise cessation of smoking, increases in physical activity and reduction in body weight. In addition insulin, biguanides, acarbose and glitazones applied for glycemic control also improve diabetic dyslipidemia. Additional pharmacological treatment of dyslipidemia if persisting after glycemic control relies on different drug classes. Fibrates effectively reduce free fatty acids, fasting and postprandial lipemia, shift the distribution of LDL particles towards less dense subfractions and increase HDL cholesterol, thus particularly addressing key components of diabetic dyslipidemia. For LDL cholesterol lowering statins are mainly used that decrease LDL cholesterol levels by competitive inhibition of the HMG-CoA reductase. As type 2 diabetes is found to be associated with a two- to fourfold increase in coronary heart disease risk and as the degree of glycemia is more related to microvascular complications, correcting dyslipidemia appears to be a major task in order to reduce macrovascular events in patients with type 2 diabetes.

Neutralizing immunogenicity of transgenic carrot (Daucus carota L.)-derived measles virus hemagglutinin

Although edible vaccines seem to be feasible, antigens of human pathogens have mostly been expressed in plants that are not attractive for human consumption (such as potatoes) unless they are cooked. Boiling may reduce the immunogenicity of many antigens. More recently, the technology to transform fruit and vegetable plants have become perfected. We transformed carrot plants with Agrobacterium tumefaciens to generate plants (which can be eaten raw) transgenic for an immunodominant antigen of the measles virus, a major pathogen in man. The hemagglutinin (H) glycoprotein is the principle target of neutralizing and protective antibodies against measles. Copy numbers of the H transgene were verified by Southern blot and specific transcription was confirmed by RT-PCR. The H protein was detected by western blot in the membrane fraction of transformed carrot plants. The recombinant protein seemed to have a 8% lower molecular weight than the viral protein. Although this suggests a different glycosylation pattern, proper folding of the transgenic protein was confirmed by conformational-dependent monoclonal antibodies. Immunization of mice with leaf or root extracts induced high titres of IgG1 and IgG2a antibodies that cross-reacted strongly with the measles virus and neutralized the virus in vitro. These results demonstrate that transgenic carrot plants can be used as an efficient expression system to produce highly immunogenic viral antigens. Our study may pave the way towards an edible vaccine against measles which could be complementary to the current live-attenuated vaccine.

Measurement of the positive muon anomalous magnetic moment to 0.7 ppm

A higher precision measurement of the anomalous g value, a(mu)=(g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron, based on data collected in the year 2000. The result a(mu(+))=11 659 204(7)(5)x10(-10) (0.7 ppm) is in good agreement with previous measurements and has an error about one-half that of the combined previous data. The present world average experimental value is a(mu)(expt)=11 659 203(8)x10(-10) (0.7 ppm).

[Increased triglycerides and/or low HDL cholesterol. A risk factor needing treatment?]

Elevated LDL (low density lipoprotein) cholesterol is considered an established risk factor for the development of atherosclerotic sequelae. In this context, low HDL cholesterol and/or raised triglyceride levels are now also receiving increasing attention as independent risk factors for atherosclerosis. The protective HDL cholesterol should be as high as possible (> 40 mg/dl or 1.0 mmol/l). Low HDL cholesterol levels are associated with an increased coronary risk that cannot be eliminated by lowering LDL cholesterol concentrations. Measures to elevate HDL are primarily dietary adjustments, cessation of smoking, weight reduction and increased physical activity. Triglyceride levels above 1000 mg/dL are also associated with an increased risk for the development of pancreatitis, and therefore also need to be treated.

Treatment of dyslipoproteinemia in the metabolic syndrome

The metabolic syndrome consists of a cluster of metabolic disorders, many of which promote the development of atherosclerosis and increase the risk to develop cardiovascular disease. The metabolic syndrome is characterized by atherogenic dyslipidemia (elevated triglycerides, increased small dense low-density lipoproteins, and decreased high-density lipoproteins), hypertension, insulin resistance and obesity. To decrease the risk of cardiovascular disease events decreasing body weight by ingesting a healthy diet, increasing physical activity, cessation of smoking and managing dyslipidemia are recommended. Pharmacological treatment of dyslipidemia is based on different drug classes. For LDL-cholesterol-lowering mainly statins and for triglyceride-lowering mainly fibrates are used. In primary and secondary prevention trials of heart disease they have shown to reduce the incidence of coronary artery disease or coronary events by 25-60 percent. Statins reduce mainly LDL-cholesterol levels by competitive inhibition of HMG-CoA reductase but have also shown to reduce fasting and postprandial triglyceride levels. Fibrates effectively reduce fasting and postprandial lipemia, shift the distribution of LDL particles towards less dense particles and increase HDL-cholesterol. Thus fibrates particularly address components of the metabolic syndrome and features of diabetic dyslipidemia. However studies still are needed showing definite evidence on differential therapy in lipid lowering based on prospective controlled trials with endpoints of macro- and microangiopathy in diabetic patients.

X-ray structure of the orphan nuclear receptor RORbeta ligand-binding domain in the active conformation

The retinoic acid-related orphan receptor beta (RORbeta) exhibits a highly restricted neuronal-specific expression pattern in brain, retina and pineal gland. So far, neither a natural RORbeta target gene nor a functional ligand have been identified, and the physiological role of the receptor is not well understood. We present the crystal structure of the ligand-binding domain (LBD) of RORbeta containing a bound stearate ligand and complexed with a coactivator peptide. In the crystal, the monomeric LBD adopts the canonical agonist-bound form. The fatty acid ligand-coactivator peptide combined action stabilizes the transcriptionally active conformation. The large ligand-binding pocket is strictly hydrophobic on the AF-2 side and more polar on the beta-sheet side where the carboxylate group of the ligand binds. Site-directed mutagenesis experiments validate the significance of the present structure. Homology modeling of the other isotypes will help to design isotype-selective agonists and antagonists that can be used to characterize the physiological functions of RORs. In addition, our crystallization strategy can be extended to other orphan nuclear receptors, providing a powerful tool to delineate their functions.

Surgical management of single and multiple brain metastases: results of a retrospective study

BACKGROUND

Advancement in diagnosis and treatment of various cancer entities led to an increasing incidence of brain metastases in the last decades. Surgical excision of single and multiple brain metastases is one of the central treatment options beside radiotherapy, radiosurgery and chemotherapy. To evaluate the benefit of surgery with/without whole-brain radiation therapy (WBRT) in single brain metastases and the influence of image guidance for brain metastases resection, 104 patients were retrospectively evaluated for post-operative outcome.

PATIENTS AND METHODS

Between January 1994 and December 1999 150 patients were surgically treated for brain metastases at the Department of Neurosurgery at the Technical University of Dresden. Outcome could be evaluated in 104 patients with respect to special treatment strategies and survival time (69 patients with single and 35 patients with multiple lesions).

RESULTS

Most metastases originated from primary lung and breast tumours. Karnofsky performance score improved on average by 10 after surgery. The extent of the extracerebral tumour burden was the main influence on survival time. Patients' age below 70 years was combined with prolonged survival time (median survival time, MST: 4.5 months vs. 7 months). Patients with solitary cerebral metastasis had a MST of 16 months, whereas patients with singular lesions had a MST of 7 and 4 months, depending on the extent of the extracerebral tumour growth. Additional post-operative WBRT with 30 Gy was combined with an increase in MST in patients with single brain metastasis (surgery + WBRT: MST 13 months; surgery only: MST 8 months). In addition, the rate of recurrent cerebral tumour growth was distinctly higher in the non-WBRT group. Neuronavigation did not significantly improve post-operative survival time. In 80% of patients extracerebral tumour growth limited patients' survival.

CONCLUSION

Surgery is an initial treatment option in patients with single and multiple brain metastases especially with large tumours (> 3 cm). Post-operative WBRT seems to prolong survival time in patients with single brain metastasis by decreasing local and distant tumour recurrence. Neuronavigational devices permit a targeted approach. Multiple processes can be extirpated in one session without prolonging the hospitalisation time for the patient. However, neuronavigational devices cannot assure complete tumour resection.

Precise measurement of the positive muon anomalous magnetic moment

A precise measurement of the anomalous g value, a(mu) = (g-2)/2, for the positive muon has been made at the Brookhaven Alternating Gradient Synchrotron. The result a(mu+) = 11 659 202(14) (6) x 10(-10) (1.3 ppm) is in good agreement with previous measurements and has an error one third that of the combined previous data. The current theoretical value from the standard model is a(mu)(SM) = 11 659 159.6(6.7) x 10(-10) (0.57 ppm) and a(mu)(exp) - a(mu)(SM) = 43(16) x 10(-10) in which a(mu)(exp) is the world average experimental value.

Cerebellar involvement in Langerhans' cell histiocytosis: a progressive neuropsychiatric disease

We describe a 21-year-old patient who was being followed since the age of 3(1/2) years for Langerhans' cell histiocytosis. Although previously a bright and gifted student, the patient presented at age 16(1/2) with new-onset cerebellar neurologic signs, obsessive-compulsive disorder, and dementia. Findings on magnetic resonance imaging study of the brain were normal, but brain single photon emission computed tomography with technetium 99m ethylene cysteinate dimer showed markedly decreased cerebellar perfusion. This case is unique for the wide extent of the central nervous system involvement in Langerhans' cell histiocytosis, which has not been reported previously. Although obsessive-compulsive disorder has also been associated with several other cerebellar disorders, it is still unknown whether the cerebellum plays a role in its development. We suggest that in some cases, brain single photon emission computed tomography may be superior to magnetic resonance imaging for demonstrating cerebellar disorder in Langerhans' cell histiocytosis.

Use of a reference material proposed by the International Federation of Clinical Chemistry and Laboratory Medicine to evaluate analytical methods for the determination of plasma lipoprotein(a)

BACKGROUND

As part of the NIH/National Heart, Lung and Blood Institute Contract for the Standardization of Lipoprotein(a) [Lp(a)] Measurements, a study was performed in collaboration with the IFCC Working Group for the Standardization of Lp(a) Assays. The aims of the study, performed with the participation of 16 manufacturers and 6 research laboratories, were to evaluate the IFCC proposed reference material (PRM) for its ability to transfer an accuracy-based value to the immunoassay calibrators and to assess concordance in results among different methods.

METHODS

Two different purified Lp(a) preparations with protein mass concentrations determined by amino acid analysis were used to calibrate the reference method. A Lp(a) value of 107 nmol/L was assigned to PRM. After uniformity of calibration was demonstrated in the 22 evaluated systems, Lp(a) was measured on 30 fresh-frozen sera covering a wide range of Lp(a) values and apolipoprotein(a) [apo(a)] sizes.

RESULTS

The among-laboratory CVs for these samples (6-31%) were, in general, higher than those obtained for PRM (2.8%) and the quality-control samples (14%, 12%, and 9%, respectively), reflecting the broad range of apo(a) sizes in the 30 samples and the sensitivity of most methods to apo(a) size heterogeneity. Thus, although all of the assays were uniformly calibrated through the use of PRM, no uniformity in results was achieved for the isoform-sensitive methods.

CONCLUSIONS

Linear regression analyses indicated that to various degrees, apo(a) size heterogeneity affects the outcome of the immunochemical methods used to measure Lp(a). We have also shown that the inaccuracy of Lp(a) values determined by methods sensitive to apo(a) size significantly affects the assessment of individual risk status for coronary artery disease.

Molecular and expression analysis of a LIM protein gene family from flowering plants

LIM-domain proteins participate in important cellular processes in eukaryotes, including gene transcription and actin cytoskeleton organization. They are predominantly found in animals, but have also been identified in yeast and plants. Following the characterization ofa LIM-domain protein in sunflower pollen, we carried out an extensive search for these proteins in flowering plants. We have isolated and studied cDNAs and/or genomic sequences for two novel LIM-domain proteins from sunflower, three from tobacco, and one from Arabidopsis. The plant proteins are structurally related to the cytoskeleton-associated CRP class of LIM proteins in animals, but show several distinctive features, including a second, atypical, LIM domain. We have performed comparative expression studies of these genes, as well as of one other gene from tobacco and two additional Arabidopsis genes whose sequences are available from databases. These studies, carried out by RT-PCR in the presence of gene-specific primers, showed that, in sunflower and tobacco, pollen grains and sporophytic tissues express different sets of LIM proteins. With the exception of one Arabidopsis gene--which has two introns--all the genes analyzed contain four introns at conserved positions, indicating that the ancestral gene from which the various copies evolved in higher plants allready had this split structure.

Methotrexate treatment protocols and the central nervous system: significant cure with significant neurotoxicity

Methotrexate can influence the central nervous system through several metabolic toxic pathways. These effects can be categorized as immediate, acute to subacute, or chronic neurologic syndromes. The acute to subacute syndrome occurs frequently in acute lymphoblastic leukemia treatment protocols, generally manifesting with focal neurologic signs and changes seen on magnetic resonance imaging and single photon emission computed tomography. While in some patients the neurotoxicity is transient and benign and allows for continuation of chemotherapy, in others it can be quite severe and debilitating, leading to permanent neurologic deficits. The need to modify the treatment protocols when neurotoxicity appears is not fully established. It is also unknown whether the use of sufficient amounts of leucovorin can overcome the toxic effects of the drug.

Structure and interfacial properties of chicken apolipoprotein A-IV

To gain insight into the evolution and function of apolipoprotein A-IV (apoA-IV) we compared structural and interfacial properties of chicken apoA-IV, human apoA-IV, and a recombinant human apoA-IV truncation mutant lacking the carboxyl terminus. Circular dichroism thermal denaturation studies revealed that the thermodynamic stability of the alpha-helical structure in chicken apoA-IV (DeltaH = 71.0 kcal/mol) was greater than that of human apoA-IV (63.6 kcal/mol), but similar to that of human apoA-I (73.1 kcal/mol). Fluorescence chemical denaturation studies revealed a multiphasic red shift with a 65% increase in relative quantum yield that preceded loss of alpha-helical structure, a phenomenon previously noted for human apoA-IV. The elastic modulus of chicken apoA-IV at the air/water interface was 13.7 mN/m, versus 21.7 mN/m for human apoA-IV and 7.6 mN/m for apoA-I. The interfacial exclusion pressure of chicken apoA-IV for phospholipid monolayers was 31.1 mN/m, versus 33.0 mN/m for human A-I and 28.5 mN/m for apoA-IV. We conclude that the secondary structural features of chicken apoA-IV more closely resemble those of human apoA-I, which may reflect the evolution of apoA-IV by intraexonic duplication of the apoA-I gene. However, the interfacial properties of chicken apoA-IV are intermediate between those of human apoA-I and apoA-IV, which suggests that chicken apoA-IV may represent an ancestral prototype of mammalian apoA-IV, which subsequently underwent further structural change as an evolutionary response to the requisites of mammalian lipoprotein metabolism.

[Lipoprotein and apolipoprotein electrophoresis in X-chromosome recessive ichthyosis]

BACKGROUND AND OBJECTIVE

The clinical differentiation of the hereditary ichthyosis forms is difficult and without laboratory markers hardly possible. Serum lipoprotein electrophoresis is one tool for detecting patients with recessive X-linked ichthyosis (XRI). Compared to controls, XRI patients show elevated electrophoretic mobilities of low density (LDL) and very low density lipoproteins (VLDL). This change in pattern is only partially explained by the increased LDL cholesterin sulfate concentration and is the subject of this study.

PATIENTS/METHODS

Patients suffering from XRI and ichthyosis vulgaris, healthy controls. SDS-PAGE-electrophoresis and isoelectric focusing for detection of XRI-associated variations in apolipoproteins apo B-100, apo C-III and apo E.

RESULTS

XRI-associated apolipoprotein variants were not found. In contrast to the literature, an increased electrophoretic mobility was also observed for HDL (high density lipoproteins) from XRI patients.

CONCLUSIONS

The underlying cause of the increased electrophoretic mobility of VLDL and HDL in XRI patients remains unclear. Future studies should investigate other apolipoproteins and verify the cholesterin sulfate concentrations reported for VLDL and HDL from XRI patients.

Increased production of HDL ApoA-I in homozygous familial defective ApoB-100

Familial defective apolipoprotein (apo) B-100 (FDB) is a frequent cause of hypercholesterolemia. Hypercholesterolemia in homozygous FDB is less severe than in homozygotes for familial hypercholesterolemia. Recently, we showed decreased low density lipoprotein (LDL) apoB-100 fractional catabolism and decreased production of LDL due to an enhanced removal of apoE-containing precursors in a patient with homozygous FDB. The effects of defective apoB-100 on high density lipoprotein (HDL) metabolism are unknown. We studied HDL apoA-I metabolism in this FDB patient and in 6 control subjects by using (2)H(3)-L-leucine as a tracer. ApoA-I levels were normal in all study subjects. However, the fractional catabolic rate and the production rate of apoA-I were increased, by 79% and 70%, respectively, in FDB; the fractional catabolic rate of apoA-I in FDB was 0.34 day(-1) compared with 0.19+/-0.03 day(-1) in normal controls. The production rate of apoA-I in FDB was 18.4 mg. kg(-1). d(-1) compared with 10.8+/-2.3 mg. kg(-1). d(-1) in controls. Thus, we have shown for the first time that defective apoB-100 may influence HDL kinetics. The increase in total HDL turnover might enhance reverse cholesterol transport and could contribute to the seemingly benign clinical course of FDB compared with that of familial hypercholesterolemia.

Investigation by isoelectric focusing of the initial carbohydrate-deficient transferrin (CDT) and non-CDT transferrin isoform fractionation step involved in determination of CDT by the ChronAlcoI.D. assay

BACKGROUND

The introduction of a new set of reagents for the determination of carbohydrate-deficient transferrin (CDT) as a marker of chronic alcohol abuse requires an independent evaluation of the analytic specificity of the test. This information is needed for correct interpretation and classification of test results.

METHODS

Isoelectric focusing on the PhastSystem(TM) followed by immunofixation, silver staining, and densitometry was used to validate the initial transferrin isoform fractionation step on anion-exchange microcolumns involved in the ChronAlcoI.D. assay.

RESULTS

The in vitro transferrin iron load was complete and stable. The CDT and non-CDT transferrin fractionation on anion-exchange microcolumns was reliable and reproducible (CV < or = 10%). Except for quantitatively unimportant traces of trisialo-Fe(2)-transferrin (<5% of total CDT), only asialo-, mono-, and disialo-Fe(2)-transferrin were detected in the microcolumn eluates (n = 170). There was a loss of proportionally similar amounts of asialo-Fe(2)-transferrin (during column rinsing) and disialo-Fe(2)-transferrin (on the anion exchanger). Thus, the peak height ratios for disialo- and asialo-Fe(2)-transferrin did not change from >1 (serum) to <1 (eluates) as described for the CDTect assays. The transferrin patterns in the ChronAlcoI.D. eluates were representative of those in serum. Transferrin D variants with isoelectric points close to that of trisialo-Fe(2)-transferrin C1 did not cause overdetermination of CDT by the ChronAlcoI.D. test.

CONCLUSIONS

The initial CDT and non-CDT fractionation step involved in determination of CDT by the ChronAlcoI.D. assay is efficient for eliminating non-CDT transferrins from serum before quantification of CDT in the final turbidimetric immunoassay. We recommend IEF for validation of other (commercial) CDT analysis methods and of odd CDT results.

A LIM-domain protein from sunflower is localized to the cytoplasm and/or nucleus in a wide variety of tissues and is associated with the phragmoplast in dividing cells

LIM proteins are important eucaryotic developmental regulators characterized by the presence of one or several double zinc finger motifs, the LIM domains, which are protein-interacting domains. Using the cDNA of the previously described pollen LIM protein PLIM1 from sunflower as a hybridization probe we have isolated the coding sequence for a related protein from cDNA libraries from various sunflower organs. This protein, WLIM1, is 188 amino acids long and, like the pollen protein PLIM1, contains two LIM domains, separated by a 48 residue spacer region. The two sunflower proteins are structurally related to the animal LIM proteins CRP and MLP. A WLIM1 gene transcript was detected by RT-PCR in all vegetative and reproductive plant organs tested. Polyclonal antibodies raised against the bacterially expressed and affinity-purified protein recognize a polypeptide of ca. 50 kDa in these organs. Immunocytochemical studies detect the protein in many cell types in each of these organs where it is localized either to the cytoplasm, the nucleus, or both. The protein is often associated with plastids and smaller cellular structures or organelles. In late anaphase and early telophase of dividing cells from ovaries, stems and roots it accumulates in the phragmoplast, and may therefore also play a role in cytokinesis.

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. In confluent cells incubated with 1 mM oleic (n-9), linoleic (n-6), alpha-linolenic (n-3), or docosahexaenoic (n-3) acids for a long-term period, both apo A-IV protein levels and de novo synthesis were increased. The induction resulted from the up-regulation of apo A-IV mRNA transcripts. In contrast, an inhibitory effect was evident with short-term incubation. FA chain length and degree of unsaturation had little effect altering apo A-IV transcript and biogenesis. These data offer evidence that isolated fatty acids regulate gene expression and the production of apo A-IV in the enterocyte.

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. Results of precision and linearity testing were comparable for all materials whereas testing for the harmonization effect resulted in an among-assay coefficient of variation for corrected lipoprotein(a) values of between 11% and 22%. The material that gave maximum harmonization achieved a variation of < 8% for 18 immunonephelometric and immunoturbidimetric assay systems. It can be hypothesized that this residual variation in part takes into account the inaccuracy of lipoprotein(a) measurement due to apolipoprotein(a) size polymorphism. On the basis of acceptable analytical performance, maximal harmonization effect and documented stability, a lyophilized material has been selected as the common calibrator for lipoprotein(a) to be used in a value transfer procedure by diagnostic companies.

Evolving functions of apolipoprotein AIV: from birds to mammals

Apolipoprotein (apo) AIV is a serum protein that displays particularly vivid dynamics regarding its distribution among the various plasma lipoprotein and nonlipoprotein fractions. This article discusses two main aspects. First, the general functional properties of apo AIV as a highly mobile and versatile apolipoprotein, delineated in mammalian species, are described. Second, the implications of the fact that not only mammals, but also the chicken, express apo AIV are highlighted. Given the differences in certain lipid metabolic pathways between mammals and birds, the structure and functions of apo AIV may have evolved into distinct functions in different amniotes.