Michel Langlois

Hemopexin: a review of biological aspects and the role in laboratory medicine.

BACKGROUNDnHemopexin is a heme-binding plasma glycoprotein which, after haptoglobin, forms the second line of defense against hemoglobin-mediated oxidative damage during intravascular hemolysis. A decrease in plasma hemopexin concentration reflects a recent release of heme compounds in the extracellular compartment. Heme-hemopexin complexes are delivered to hepatocytes by receptor-mediated endocytosis after which hemopexin is recycled to the circulation.nnnMETHODS OF ANALYSISnImmunonephelometric and -turbidimetric hemopexin assays are available as more precise and rapid alternatives to the radial immunodiffusion technique.nnnINTERPRETATIONSnHemopexin determinations are not subject to interference by in vitro hemolysis. Altered serum or plasma concentrations of hemopexin are found not only in hemolytic anemias but also in other conditions such as chronic neuromuscular diseases and acute intermittent porphyria. In laboratory medicine, while hemopexin determination in tandem with haptoglobin has potential applications in the assessment of intravascular hemolysis and allows for the monitoring of the severity of hemolysis after depletion of haptoglobin, its diagnostic utility is less clear in other pathological conditions. Further studies are necessary to fully establish the clinical significance of hemopexin determination.

Serum Vitamin C Concentration Is Low in Peripheral Arterial Disease and Is Associated With Inflammation and Severity of Atherosclerosis

BackgroundPeripheral arterial disease (PAD) is a severe atherosclerotic condition frequently accompanied by inflammation and oxidative stress. We hypothesized that vitamin C antioxidant levels might be low in PAD and are related to inflammation and disease severity. Methods and ResultsWe investigated vitamin C (l-ascorbic acid) levels in 85 PAD patients, 106 hypertensives without PAD, and 113 healthy subjects. Serum l-ascorbic acid concentrations were low among PAD patients (median, 27.8 &mgr;mol/L) despite comparable smoking status and dietary intake with the other groups (P <0.0001). Subclinical vitamin C deficiency (<11.4 &mgr;mol/L), confirmed by low serum alkaline phosphatase activity, was found in 14% of the PAD patients but not in the other groups. Serum C-reactive protein (CRP) concentrations were significantly higher in PAD patients (P <0.0001) and negatively correlated with l-ascorbic acid levels (r =−0.742, P <0.0001). In stepwise multivariate analysis, low l-ascorbic acid concentration in PAD patients was associated with high CRP level (P =0.0001), smoking (P =0.0009), and shorter absolute claudication distance on a standardized graded treadmill test (P =0.029). ConclusionsVitamin C concentrations are lower in intermittent claudicant patients in association with higher CRP levels and severity of PAD. Future studies attempting to relate vitamin C levels to disease occurrence should include in their analysis an inflammatory marker such as CRP.

Management of familial hypercholesterolemia in children and young adults: Consensus paper developed by a panel of lipidologists, cardiologists, paediatricians, nutritionists, gastroenterologists, general practitioners and a patient organization

UNLABELLEDnSince heterozygous familial hypercholesterolemia (HeFH) is a disease that exposes the individual from birth onwards to severe hypercholesterolemia with the development of early cardiovascular disease, a clear consensus on the management of this disease in young patients is necessary. In Belgium, a panel of paediatricians, specialists in (adult) lipid management, general practitioners and representatives of the FH patient organization agreed on the following common recommendations. 1. Screening for HeFH should be performed only in children older than 2 years when HeFH has been identified or is suspected (based on a genetic test or clinical criteria) in one parent.2. The diagnostic procedure includes, as a first step, the establishment of a clear diagnosis of HeFH in one of the parents. If this precondition is satisfied, a low-density-lipoprotein cholesterol (LDL-C) levelabove 3.5 mmol/L (135 mg/dL) in the suspected child is predictive for differentiating affected from non-affected children. 3. A low saturated fat and low cholesterol diet should be started after 2 years, under the supervision of a dietician or nutritionist.4. The pharmacological treatment, using statins as first line drugs, should usually be started after 10 years if LDL-C levels remain above 5 mmol/L (190 mg/dL), or above 4 mmol/L (160 mg/dL) in the presence of a causative mutation, a family history of early cardiovascular disease or severe risk factors. The objective is to reduce LDL-C by at least 30% between 10 and 14 years and, thereafter, to reach LDL-C levels of less than 3.4 mmol/L (130 mg/dL).nnnCONCLUSIONnThe aim of this consensus statement is to achieve more consistent management in the identification and treatment of children with HeFH in Belgium.

Haptoglobin phenotype 2-2 overrepresentation in Cys282Tyr hemochromatotic patients.

BACKGROUND/AIMSnPatients with genotypic Cys282Tyr homozygous hemochromatosis differ largely in phenotypic presentation. The HFE mutation on itself does not explain the different manifestations of hemochromatosis. We hypothesized that the genetic haptoglobin (Hp) polymorphism, because of its effect on iron metabolism, could be a modifying factor that influences the clinical presentation of hereditary hemochromatosis.nnnMETHODSnIn 167 Cys282Tyr homozygous hemochromatotic patients, the frequencies of Hp types (1-1, 2-1 and 2-2) and alleles (Hp1, Hp2) were compared with those in 918 healthy subjects. Clinical and laboratory indices of iron overload were incorporated in the analysis.nnnRESULTSnThe Hp 2-2 type was overrepresented in the patient group (P<0.01). Male patients carrying Hp 2-2 had higher serum iron (P=0.003) and ferritin levels (P=0.03) than those with a Hp 1-1 or 2-1 type. The amount of iron removed with phlebotomy was also higher in Hp 2-2 patients (P=0.03).nnnCONCLUSIONSnThe Hp 2-2 type is overrepresented among Cys282Tyr homozygous hemochromatotic patients. At diagnosis, iron overload was more pronounced in male patients carrying Hp 2-2. Our data suggest that Hp polymorphism affects iron metabolism in hereditary hemochromatosis.

Fast determination of haptoglobin phenotype and calculation of hemoglobin binding capacity using high pressure gel permeation chromatography

A new and fast method for haptoglobin (Hp) phenotyping was developed based on high pressure gel permeation chromatography of hemoglobin-supplemented serum. Haptoglobin phenotypes 1-1, 2-1, and 2-2 are resolved on the difference in size of their hemoglobin-haptoglobin complexes. Results are available in less than 15 min. Results of the chromatographic typing correspond to those obtained by conventional starch gel electrophoresis. Next to the phenotyping of haptoglobin, the method allows reproducible calculation of the hemoglobin binding capacity (HBC) of human serum. Using this methodology, reference values for HBC were found to be 0. 75+/-0.25 g/l, with the lowest HBC in Hp 2-2 subjects and the highest in Hp 1-1 subjects (P<0.05). In contrast to earlier findings, the ratio HBC:Hp concentration was found to be comparable for the three Hp types. In conclusion, this method allows a rapid phenotyping in critical clinical conditions where Hp phenotyping can be useful, e.g. determining the donors phenotype in liver transplantation.

Discriminative value of serum amyloid A and other acute-phase proteins for coronary heart disease

We studied the value of serum amyloid A (SAA), a first-class acute-phase protein, as a marker for coronary heart disease (CHD) in a middle-aged male population. In a working population of 16307 men (age, 35-59 years), 446 cases had a history of CHD or prominent Q:QS waves on electrocardiogram. For each case, two matched controls were investigated. SAA, measured by immunonephelometry, was correlated with other acute-phase proteins, cardiovascular risk factors, and infectious serology markers. SAA concentrations were significantly higher in the cases than in controls (P<0.05) and correlated with serum C-reactive protein (CRP) (r=0.61), plasma fibrinogen (r=0.39), serum haptoglobin (r=0.26), and body mass index (r=0.13) (P<0.001). Serum CRP is a better marker for CHD than SAA, which showed discriminative power only in a univariate model comparing highest versus lowest tertile (odds ratio, 1.39; 95% confidence interval, 1.03-1.87). Neither SAA nor other acute-phase proteins correlated with Chlamydia pneumoniae immunoglobulin (Ig)G, Helicobacter pylori IgG and IgA, and cytomegalovirus IgG. In conclusion, although SAA has a discriminative value for CHD, serum CRP is to be preferred as a first-class acute-phase reactant for detection of the disease.

The effect of supplementation with an antioxidant preparation on LDL-oxidation is determined by haptoglobin polymorphism

Abstract The genetic polymorphism of haptoglobin (Hp) is an independent risk factor in the pathogenesis of atherosclerosis, a condition in which decreased resistance to in vitro oxidation of LDL-cholesterol is observed. We hypothesised that the Hp polymorphism is one of the factors modulating the resistance to Cu2+-induced oxidation of LDL during antioxidant supplementation. In this study, 74 middle-aged subjects with increased oxidative stress were allocated to either matched placebo or oral antioxidative treatment (Quatral®) once daily for 16 weeks. Study parameters were increase of lag phase (ΔLAG) and the ratio of lag phase during treatment period versus baseline (relative oxidation resistance, ROR), measured by Cu2+-induced oxidation of isolated LDL. Hp phenotypes were determined by starch gel electrophoresis. A significant and persistent increase of ΔLAG (P < 0.05) and ROR (P < 0.01) were observed after 16 weeks of active treatment versus placebo. Interindividual differences in both parameters were significantly associated with the Hp polymorphism: in the active treatment group, ΔLAG and ROR were significantly higher in Hp 1-1 subjects (P < 0.01) compared to Hp 2-1 and 2-2. Our data demonstrate that Hp phenotype is one of the modulating factors determining the increased resistance to Cu2+-induced oxidation of LDL during antioxidative treatment.

The relationship between diet and subclinical atherosclerosis: results from the Asklepios Study

Background/Objectives:Nutritional epidemiology shifted its focus from effects of single foods/nutrients toward the overall diet. Food-based dietary guidelines (FBDGs) are promoted worldwide to stimulate a healthy diet, including a variety of foods, to meet nutrient needs and to reduce the risk for non-communicable diseases. The objective of this study was to investigate whether adherence to the FBDG is associated with reduced femoral/carotid atherosclerosis and/or inflammation.Subjects/Methods:In October 2002, 2524 healthy men and women aged 35–55 years were recruited for the Belgian Asklepios cohort study. Subjects were extensively phenotyped, including echographic assessment of (carotid and femoral) atherosclerosis. A dietary index consisting of three subscores (dietary quality, diversity and equilibrium) was calculated to measure adherence to the Flemish FBDG, using data from a semi-quantitative food-frequency questionnaire. General linear models were used to investigate associations between these scores and cardiovascular (CV) risk factors and atherosclerosis and inflammation markers.Results:Women had better overall dietary scores than men (69 vs 59%). Participants with higher dietary scores showed better age-adjusted CV risk profiles (lower waist/hip ratio, blood pressure, non-high-density lipoprotein-cholesterol, blood triglycerides and homocystein), although most of these associations were only significant in men. Higher dietary scores were also inversely associated with inflammation makers (interleukin-6 and leukocyte count). Associations between diet and atherosclerosis were only found for femoral atherosclerosis and significance disappeared after adjustment for confounders.Conclusions:Better adherence to the Flemish FBDG is associated with a better CV risk profile and less inflammation, mainly among men. There was no direct effect on the presence of carotid or femoral atherosclerosis.

Effect of haptoglobin phenotypes on growth of Streptococcus pyogenes

Abstract The haptoglobin (Hp) 2–1 and 2–2 phenotypes have been shown to agglutinate Streptococcus pyogenes carrying the membrane antigen T4. In this study, the growth rate of two strains of Streptococcus pyogenes (T1 and T4) in human serum was compared among haptoglobin phenotypes in vitro. During incubation for 16 hours in serum of different haptoglobin types, only Hp 2–1 and Hp 2–2 sera showed an inhibitory effect on growth, Hp 2–2 being 1.85 times more potent than Hp 2–1. Growth of Streptococcus pyogenes T4 negatively correlated with the serum concentration of Hp 2–1 (r = −0.908) and Hp 2–2 (r = −0.953). Haptoglobin-depleted serum had no inhibitory effect on bacterial growth. Addition of haemoglobin and ferric citrate to the serum accelerated the growth of Streptococcus pyogenes T4 (P < 0.05) but not in Hp 2–2 serum. Haptoglobin types 2–1 and 2–2 can be regarded as inhibitors of Streptococcus pyogenes growth in vitro. These data point towards a potential protective role of Hp 2–2 in Streptococcus pyogenes infection in vivo, independently of iron uptake.

The prognostic significance of the DNA content in Ewing's sarcoma: a retrospective cytophotometric and flow cytometric study.

The DNA content of the cell nuclei of Ewings sarcoma was analysed by means of cytophotometry in situ with image analysis in Feulgen‐stained sections in 37 patients, and by retrospective flow cytometry according to the method of Hedley in 26 patients. Different histogram patterns were obtained: normal unimodal or bimodal DNA distributions and abnormal DNA distributions with one or two stem lines, or an abnormal DNA distribution with no stem lines. Both methods enabled us to make a distinction between two groups of Ewings sarcomas with a different prognosis. All patients with aneuploid tumours died within 5 years after the initial diagnosis. Eleven of 19 (58%) patients with a normal DNA distribution in their tumour, as determined by cytophotometry, are still alive and in good health with a mean survival period of 7.5 years, ranging from 2 to 19 years. Of the group of patients in which flow cytometry revealed a normal DNA pattern, eight of 15 (53%) are still alive and in good health, with a mean survival period of 8 years. These results indicate that both techniques are reliable methods for obtaining prognostic information in Ewings sarcomas. However, cytophotometry in situ yielded a better discrimination for the overall survival (P < 0.01) than did flow cytometry (P <0.05). In 19% of the cases there was a discrepancy between the DNA histograms obtained with the two techniques. In five of 26 cases the DNA distributions were classified as normal by one method and aneuploid by the other. Tumour cell representation or selective loss of cells during enzymatic treatment may be responsible for this discrepancy.