Advanced phenotyping in hypersensitivity drug reactions to NSAIDs

Non-steroidal anti-inflammatory drugs (NSAIDs) are the medications most frequently involved in hypersensitivity drug reactions. Because NSAIDs are prescribed for many conditions, this is a world-wide problem affecting patients of all ages. Various hypersensitivity reactions have been reported, mainly affecting the skin and/or the respiratory airways. The most frequent of these is acute urticaria, which can be induced by several different NSAIDs. Both specific and non-specific immunological pathways have been proposed as underlying mechanisms. This review presents the clinical phenotypes and the drugs involved in NSAID hypersensitivity. Five major clinical syndromes can be distinguished: aspirin-exacerbated respiratory disease (AERD), aspirin-exacerbated cutaneous disease (AECD), multiple NSAID-induced urticaria/angioedema (MNSAID-UA), single NSAID-IgE reactions and single NSAID T cell responses. However, further classification is possible within these five major entities, by detailed descriptions of the clinical characteristics enabling more phenotypes to be defined. This detailed differentiation now seems required in order to undertake appropriate pharmacogenetic studies.

Contributions of pharmacogenetics and transcriptomics to the understanding of the hypersensitivity drug reactions

Hypersensitivity drug reactions (HDRs) represent a large and important health problem, affecting many patients and leading to a variety of clinical entities, some of which can be life-threatening. The culprit drugs include commonly used medications including antibiotics and NSAIDs. Nontherapeutical agents, such as contrast media, are also involved. Because the pathophysiological mechanisms are not well known and the current diagnostic procedures are somewhat insufficient, new approaches are needed for understanding the complexity of HDRs. Histochemical and molecular biology studies have enabled us to classify these reactions more precisely. Pharmacogenetics has led to the identification of several genes, involved mainly in T-cell-dependent responses, with a number of markers being replicated in different studies. These markers are now being considered as potential targets for reducing the number of HDRs. Transcriptomic approaches have also been used to investigate HDRs by identifying genes that show different patterns of expression in a number of clinical entities. This information can be of value for further elucidation of the mechanisms involved. Although first studies were performed using RT-PCR analysis to monitor the acute phase of the reaction, nowadays high-density expression platforms represent a more integrative way for providing a complete view of gene expression. By combining a detailed and precise clinical description with information obtained by these approaches, we will obtain a better understanding and management of patients with HDRs.

Allergy to betalactams and nucleotide-binding oligomerization domain (NOD) gene polymorphisms

BACKGROUND

Polymorphisms of interleukin genes related to IgE production and inflammation are predictors of hypersensitivity to betalactam, but nothing is known on the influence of NOD genes, despite their association with inflammation and atopy.

OBJECTIVE

To evaluate the association of NOD2 and NOD1 polymorphisms with betalactam allergy.

METHOD

We genotyped 3 polymorphisms of NOD2 and 1 of NOD1 in 368 Italian and 387 Spanish patients, compared with 368 and 326 controls, respectively.

RESULTS

CT/TT genotypes of rs2066845 of NOD2 predicted a lower risk in Italy (P = 0.003), while WT/insC genotype of rs5743293 (also in leucine-rich repeat domain) predicted a higher risk in Spain (P = 0.007). G allele of rs2066845 was associated with a higher level of IgE in the Italian population.

CONCLUSION

The mirrored influence of these NOD2 polymorphisms on betalactam allergy in two populations suggests a link with pathways of inflammation and/or atopy through mechanisms, which need to be clarified.

Homocysteine predicts increased NT-pro-BNP through impaired fatty acid oxidation

BACKGROUND

The deficiency in methyl donors, folate and vitamin B12, increases homocysteine and produces myocardium hypertrophy with impaired mitochondrial fatty acid oxidation and increased BNP, through hypomethylation of peroxisome-proliferator-activated-receptor gamma co-activator-1α, in rat. This may help to understand better the elusive link previously reported between hyperhomocysteinemia and BNP, in human. We investigated therefore the influence of methyl donors on heart mitochondrial fatty acid oxidation and brain natriuretic peptide, in two contrasted populations.

METHODS

Biomarkers of heart disease, of one carbon metabolism and of mitochondrial fatty acid oxidation were assessed in 1020 subjects, including patients undergoing coronarography and ambulatory elderly subjects from OASI cohort.

RESULTS

Folate deficit was more frequent in the coronarography population than in the elderly ambulatory volunteers and produced a higher concentration of homocysteine (19.3 ± 6.8 vs. 15.3 ± 5.6, P<0.001). Subjects with homocysteine in the upper quartile (≥ 18 μmol/L) had higher concentrations of NT-pro-BNP (or BNP in ambulatory subjects) and of short chain-, medium chain-, and long chain-acylcarnitines, compared to those in the lower quartile (≤ 12 μmol/L), in both populations (P<0.001). Homocysteine and NT-pro-BNP were positively correlated with short chain-, medium chain-, long chain-acylcarnitines and with acylcarnitine ratios indicative of decreased mitochondrial acyldehydrogenase activities (P<0.001). In multivariate analysis, homocysteine and long chain acylcarnitines were two interacting determinants of NT-pro-BNP, in addition to left ventricular ejection fraction, body mass index, creatinine and folate.

CONCLUSIONS

This study showed that homocysteine predicts increased NT-pro-BNP (or BNP) through a link with impaired mitochondrial fatty oxidation, in two contrasted populations.

Hypersensitivity reactions to neuromuscular blocking agents

Neuromuscular blocking agents are the leading drugs responsible for immediate hypersensitivity reactions during anaesthesia. Most hypersensitivity reactions represent IgE-mediated allergic reactions. Their incidence is estimated to be between 1 in 3,000 to 1 in 110,000 general anaesthetics. However striking variations have been reported among countries. The mechanism of sensitisation seems to implicate the presence of a substituted ammonium ion in the molecule. Due to lack of exposure prior to the reaction in a large number of reactors, it has been hypothesised that sensitisation may involve other, as yet undefined, substituted (quaternary and tertiary) ammonium ion containing compounds such as pholcodine, present in the environment of the patient. This hypothesis is still under investigation. The mechanism of non-IgE mediated hypersensitivity reactions is less well known. Identified mechanisms correspond to direct histamine release or interactions with muscarinic and nicotinic receptors. Allergic reactions cannot be clinically distinguished from non-IgE-mediated reactions. Therefore, any suspected hypersensitivity reaction must be investigated using combined pre and postoperative testing. Because of the frequent but not systematic cross-reactivity observed with muscle relaxants, every available neuromuscular blocking agent should be tested, using intradermal tests to confirm the responsibility of the suspected drug which should be definitely excluded. Cross-sensitivity investigation will also try to identify the safety of drugs that can be potentially used in future anaesthesia. The determination of basophil activation investigations using direct leukocyte histamine release test or flow cytometry would be of particular interest to investigate cross sensitisation in complement to skin tests. There is no demonstrated evidence supporting systematic pre-operative screening in the general population at this time. However, since no specific treatment has been shown to reliably prevent anaphylaxis, allergy assessment must be performed in all high-risk patients. In view of the relative complexity of allergy investigation, and of the differences between countries, an active policy to identify patients at risk and to provide any necessary support from expert advice to anaesthetists and allergologists through the constitution of allergo-anaesthesia centres in every country should be promoted.

Impact of folate and homocysteine metabolism on human reproductive health

Folates belong to the vitamin B group and are involved in a large number of biochemical processes, particularly in the metabolism of homocysteine. Dietary or genetically determined folate deficiency leads to mild hyperhomocysteinemia, which has been associated with various pathologies. Molecular mechanisms of homocysteine-induced cellular dysfunction include increased inflammatory cytokine expression, altered nitric oxide bioavailability, induction of oxidative stress, activation of apoptosis and defective methylation. Whereas the involvement of folate metabolism and homocysteine in ageing-related diseases, in several developmental abnormalities and in pregnancy complications has given rise to a large amount of scientific work, the role of these biochemical factors in the earlier stages of mammalian reproduction and the possible preventive effects of folate supplementation on fertility have, until recently, been much less investigated. In the present article, the possible roles of folates and homocysteine in male and female subfertility and related diseases are systematically reviewed, with regard to the epidemiological, pathological, pharmacological and experimental data of the literature from the last 25 years.

Nutritional value of proteins from edible seaweed Palmaria palmata (dulse)

Palmaria palmata (Dulse) is a red seaweed that may be a potential protein source in the human diet. Its protein content, amino acid composition, and protein digestibility were studied with algae collected every month over a 1-year period. Significant variations in protein content were observed according to the season: The highest protein content (21.9 +/- 3.5%) was found in the winter-spring period and the lowest (11.9 +/- 2.0%) in the summer-early autumn period. Most of the essential amino acids were present throughout the year. After 6-hour in vitro digestion in a cell dialysis using porcine pepsin and porcine pancreatin, the digestibility of proteins from Palmaria palmata crude powder, represented by dialyzed nitrogen, was estimated at 29.52 +/- 1.47%. Relative digestibility was 56%, using casein hydrolysis as 100% reference digestibility. In vitro digestibility of proteins extracted in water was analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis using either bovine trypsin, bovine chymotrypsin, pronase from Streptomyces griseus, or human intestinal juice. Dulse proteins were hydrolyzed to a limited extent, which confirmed a rather low digestibility. Hydrolysis rate was higher with trypsin and lower with chymotrypsin compared with the two other enzymatic systems, pronase and intestinal juice, respectively. The association of algal powder and protein extract to casein and bovine serum albumin, respectively, produced a significant decrease in the hydrolysis rate of the standard proteins. In conclusion, the digestibility of Palmaria palmata proteins seems to be limited by the algae non-proteic fraction.

Transcobalamin and methionine synthase reductase mutated polymorphisms aggravate the risk of neural tube defects in humans

The pathogenic mechanism of neural tube defects may involve genetic polymorphisms and nutritional factors related to homocysteine metabolism. We evaluated the association of polymorphisms of three genes affecting vitamin B12-dependent remethylation of homocysteine, transcobalamin (TC), methionine synthase (MTR) and MTR reductase (MTRR), combined or not with methylenetetrahydrofolate reductase (MTHFR), with the risk of having neural tube defect in 40 children with spina bifida and 58 matched controls from South Italy. MTR 2756 AG/GG, TC 777 CG/GG /MTHFR 677 CC and MTRR 66 GG /MTHFR 677 CC genotypes increased the risk with odds ratios of 2.6 (P=0.046), 2.4 (P=0.028) and 4.5 (P=0.023), respectively. In contrast, MTHFR 677 TT was protective (odds ratio=0.11, P=0.009). In conclusion, genetic determinants affecting the cellular availability or MTRR-dependent reduction of B12 may increase the risk of spina bifida.

Brown Norway rat ovalbumin-specific immunoglobulin E antibodies increase the human basophil expression of CD63 marker

Anaphylactic shock is an immunoglobulin E (IgE)-dependent hypersensitivity. Biological tests like leucocyte histamine release (LHR) and human basophil activation (HBA), frequently used in human allergy, reflect both the amount of IgE fixed on cells and the cellular reactivity. To assess whether serum-specific IgE from Brown Norway (BN) rats prepared for ovalbumin (OVA)-induced anaphylactic shocks can activate human basophils which has a potential interest in experimental allergy: such a test could rapidly assert an IgE sensitization in laboratory animals genetically T-helper 2 (Th2)-predisposed. Rats (n = 39) were immunized three times (day 0, day 5 and day 21) with OVA injected subcutaneously. One week after the third immunization, a shock was induced with an intravenous (i.v.) bolus of OVA. Sensitization was assessed by passive cutaneous anaphylaxis (PCA) test and dosages of serum IgE antibodies anti-OVA by enzyme-linked immunosorbent assay. Blood basophils were counted before and during the shock. Before the shock induction (at day 21), an LHR test was performed on rat blood, and human basophils were sensitized with rat sera. HBA was demonstrated by the increase in the percentage of cells expressing CD63 antigen membrane, measured by flow cytometry. Twenty-one days after the first subcutaneous (s.c.) immunization, the rat serum induced a significant HBA. HBA was observed neither with the same serum previously heated nor with the serum from nonimmunized rats (NIRs). OVA-specific IgEs were significantly increased in immunized rat (IR) serum. The PCA test was negative when the serum was previously heated (56 degrees C). We never observed any circulating basophils, and LHR test was negative. After OVA i.v. administration, all IRs died rapidly. HBA testing strongly suggests a mediation by specific IgE in the increase of CD63 in BN rats. Thus, HBA test seems useful in assessing whether an experimental allergy was induced in animals genetically predisposed to an immune response, Th2-mediated, like BN rat. We also conclude that rat basophil activation does not participate in the histamine release during anaphylactic shock in sensitized BN rats.

Paracellular transport of avidin saturated or not with biotinylated cobalamin through Caco-2 cell epithelium monolayer

BACKGROUND

The cationic charge of molecules may promote their uptake across epithelia, which are rich in brush border anionic sites. The transport of unsaturated avidin and avidin saturated with a biotinylated compound was investigated across Caco-2 adenocarcinoma cell with fetal enterocyte phenotype.

METHODS

The unsaturated avidin and avidin saturated with either biotin or a biotinyl-cobalamin conjugate (biotinyl-Cbl) were iodinated to follow their transport through the cell monolayer. Their apparent permeability coefficient (Papp) and transepithelial pathway were determined and compared to those for control radiolabeled markers [3H]-mannitol, [125I]-beta-lactoglobulin and [57Co]-cobalamin/intrinsic factor (Cbl/IF).

RESULTS

The Papp of [125I]-avidin estimated at 2.8 x 10(-7) +/- 0.08 cm/s was close to that for mannitol that uses paracellular pathway. The binding of biotin or biotin conjugate to avidin enhanced its tetrameric conformation. The Papp for [125I]-avidin/biotin and [125I]- avidin/biotinyl-Cbl were respectively increased by 2-fold, compared to that for [125I]-avidin and 4-fold, compared to that for [125I]-beta-lactoglobulin and [54Co]-Cbl/IF. The protein was not accumulated in the cell and was found in intact form in the basolateral side, after its transport across the monolayer. Chloroquine (0.66 micromol/ml) did not significantly decrease the Papp for [125I]-avidin/biotinyl-Cbl. Conversely it decreased by 80% the Papp for Cbl/IF, that uses transepithelial pathway.

CONCLUSIONS

Avidin (either saturated or not with biotin and biotinyl-Cbl) was able to cross the monolayer of Caco-2 cell line through a paracellular pathway. This study pointed out the interest for using this protein as a shuttle for increasing the transport rate of biotinylated compounds through fetal epithelial barriers.

Detection of moderate hyperhomocysteinemia: comparison of the Abbott fluorescence polarization immunoassay with the Bio-Rad and SBD-F high-performance liquid chromatographic assays

The importance of accurate methods for homocysteine measurement has been emphasized. We compared the results obtained with the most commonly used high-performance liquid chromatography (HPLC) assay, and two recently commercially available methods: another HPLC and a fluorescence polarization immunoassay, in plasmas from normo- or hyperhomocysteinemic patients. A significant agreement between the different methods in classifying the results as hyper or normal-homocysteinemia was observed. However, a significant difference between the results was found. Standardization is urgently necessary to improve the concordance of homocysteine determination.

Overexpression of folate binding protein alpha is one of the mechanism explaining the adaptation of HT29 cells to high concentration of methotrexate

The human colon adenocarcinoma cell line HT29 can be adapted to 10(-7)- 10(-4) M concentrations of methotrexate (MTX). Cells adapted to 10(-4) M MTX have an enterocyte-like phenotype with DHFR gene amplification. Presently, we hypothetized that an increased expression of folate binding protein (FBP) may participate to the MTX resistance of 10(-4) MTX HT29 cells. The cDNA FBPalpha/beta-actin ratio of amplified transcripts was 4.8- and 1.5- fold higher in 10(-4) and in 10(-7) M MTX HT29 respectively, than in standard type HT29 cells. An increase of transcript level was observed when decreasing folic acid concentration. PI-PLC cleaved 7.7 times more membrane FBP in 10(-4) M than in 10(-7) M MTX and wild type HT29 cells. In contrast to 10(-7) M MTX cells, growth of 10(-4) M MTX cells was dependent on folic acid concentration and abolished at a concentration lower than 0.9 microM. In conclusion, the adaptive mechanism of HT29 cells resistant to 10(-4) M MTX is the result of the synergistic overexpression of both DHFR and FBPalpha. Overexpression of FBPalpha may be related to the enterocyte-like phenotype of the cells.

Hyperhomocysteinemia is related to residual glomerular filtration and folate, but not to methylenetetrahydrofolate-reductase and methionine synthase polymorphisms, in supplemented end-stage renal disease patients undergoing hemodialysis

Glomerular filtration is one of the major determinants of plasma total homocysteine (tHcy). To evaluate the respective roles of residual glomerular filtration (by measuring a specific protein marker, cystatin C), genetic polymorphisms and nutritional status in tHcy blood levels in end-stage renal disease patients (ESRD) under hemodialysis and supplemented with folate, we measured tHcy, folate, vitamin B12 (B12), creatinine, cystatin C, albumin and C-reactive protein and determined the polymorphism of methylenetetrahydrofolate reductase (MTHFR) (C677T and A1289C) and of methionine synthase (MS) (A2756G) in 114 ESRD patients before hemodialysis and 76 control subjects. All patients received a folate supplementation of 700 microg/day. Hyperhomocysteinemia was observed in all patients and exceeded the upper normal limit by 2-fold in 52.4% of the patients. Serum folate was significantly increased and the B12 level was not different from controls. Folate, Cystatin C and creatinine were significantly correlated to tHcy, while no correlation was found between tHcy, albumin and C-reactive protein. No difference in genotype frequency between ESRD patients and controls was found for MTHFR A1289C and MS A2756G. The MTHFR 677TT genotype was less frequent and was associated with a significantly higher tHcy level in patients. Folate and residual glomerular filtration estimated by cystatin C and creatinine levels were two independent determinants of tHcy in ESRD patients. These data suggest that hyperhomocysteinemia is a consequence as well as a complicating factor of renal failure.

Comparison of effects of ioxaglate versus iomeprol on histamine and tryptase release in patients with ischemic cardiomyopathy

We observed a release of histamine, but not of tryptase, in arterial blood from 64 patients with ischemic heart disease and 24 patients without coronary disease, which was provoked by ioxaglate, a ionic compound, but was not provoked by iomeprol, a non-ionic radiocontrast compound. The release of histamine in arterial blood after ionic contrast medium injection was higher in patients with ischemic heart disease compared with patients without coronary disease, suggesting that an increased release from heart mast cells previously observed exists also for systemic blood basophils.

ApoE protects cortical neurones against neurotoxicity induced by the non-fibrillar C-terminal domain of the amyloid-beta peptide

Although the genetic link between the epsilon 4 allele of apolipoprotein E (apoE) and Alzheimer's disease (AD) is well established, the apoE isoform-specific activity underlying this correlation remains unclear. We have recently characterized the interaction of the soluble the amyloid-beta peptide (A beta) with model membrane and demonstrated that non-fibrillar A beta peptide, including N-terminal truncated forms of A beta, induced apoptotic cell death in primary rat cortical neurones in vitro. To further investigate the potential interaction between apoE and A beta in the pathogenesis of AD, we have determined the effect of apoE isoforms on the neurotoxicity of non-fibrillar A beta peptides. We demonstrate here that the apoE2 and E3 isoforms protect cortical neurones against apoptotic cell death induced by a non-fibrillar form of the A beta(1-40), A beta(12-42), A beta(29-40) and A beta(29-42) peptides, whereas apoE4 had no effect. This effect involves the formation of stable complexes between apoE and the C-terminal domain (e.g. amino acids 29-40) of A beta(1-40). Interestingly, apoE had no effect on the toxicity induced by aggregated A beta peptides, suggesting a lack of interaction between apoE and amyloid fibrils. Our results provide evidence that interaction with the C-terminal domain of A beta, apoE2 and E3, but not apoE4, inhibits the interactions of the non-fibrillar A beta peptide with the plasma membrane of neurones, A beta peptide aggregation and subsequent neurotoxicity.

Abnormal substrate levels that depend upon mitochondrial function in cerebrospinal fluid from Alzheimer patients

BACKGROUND

Impaired oxidative and energy metabolism are important features in Alzheimer's disease. These metabolic abnormalities may induce functional disturbances and are associated with significant cognitive impairment.

OBJECTIVE

To determine whether mitochondrial function is altered by Alzheimer's disease, a quantitative analysis of substrates that enter the tricarboxylic acid cycle was carried out in cerebrospinal fluid (CSF) from Alzheimer patients.

METHODS

Organic acid levels related to carbohydrate oxidation were measured in CSF from patients affected by dementia of Alzheimer type (n = 17) and from nondemented elderly controls (n = 17) using a gas chromatography/mass spectrometry system. CSF glucose and glutamine concentrations were determined by a quantitative enzymatic method and by ion exchange chromatography, respectively.

RESULTS

Compared to age-matched controls, patients had a higher CSF level of lactate (p = 0.002) and a lower mean level of succinate (p = 0.002), fumarate (p = 0.003) and glutamine (p = 0.0005). The CSF glucose level was not modified.

CONCLUSION

Our results suggest an impairment of mitochondrial oxidative metabolism in brain cells of patients with Alzheimer's disease.

Homocysteine, vitamins B6, B12, folate, and risk of coronary artery disease in patients undergoing diagnostic coronary angiography

Homocysteine and vitamins B were correlated with coronary artery disease in patients undergoing diagnostic coronary angiography. 160 patients having > or =1 stenosis (G1), 55 patients having normal coronary arteries (G2) and 171 healthy volunteers (G3) were prospectively recruited. Homocysteine levels were significantly higher in patients, particularly in those with normal coronary angiograms, than in healthy subjects (13.8 +/-6.3 micromol/L in G1 (p < 0.0001) and 15.2 +/- 8.8 micromol/L in G2 (p < 0.0001) versus 10.1 +/- 3.1 micromol/L in G3). Homocysteine levels were not related to the extent of coronary artery disease. In patients with normal angiogram, vitamin B12 and folate levels were significantly higher compared with the other groups (p < 0.05 and p < 0.001, respectively) showing that vitamin B deficiency was not involved in the hyperhomocysteinemia. In conclusion, homocysteine and vitamins B levels do not contribute to discriminate for the presence of coronary artery disease in patients undergoing diagnostic coronary angiography. Homocysteine levels, however, were higher in patients referred for coronary angiography than in healthy controls.

Sodium dodecyl sulphate gel electrophoretic preparation of protein standard human apolipoprotein B-48

Quantitation of plasma apo B-48 is currently performed by densitometric analysis of SDS-PAGE zones stained with Coomassie Brilliant Blue, using standard solutions of purified apo B-48. Here, preparative gel electrophoresis with a continuous elution system was used for purifying apo B-48. A chylomicron fraction was isolated by 107,000 g ultracentrifugation of a chylous ascite. The proteins were delipidated and precipitated in ethanol-diethyl ether (3:1, v/v), subjected to preparative electrophoresis in a 5% polyacrylamide gel and eluted in 0.1% SDS. The peak containing apo B-48 was eluted at a retention time of 445-480 min. The purity of apo B-48 in this fraction was assessed by the detection of a single band (M(r) 260,000) after silver staining and Coomassie staining of 4-15% gradient SDS-PAGE. It was confirmed by the absence of apo B-100 contaminant in Western blot of the purified protein preparation. A linear relationship was observed between the densitometric analysis of SDS-PAGE bands and the apo B-48 in a protein range of 0-3 microg. In conclusion, preparative gel electrophoresis was used in a single step purification of apo B-48 that was adapted to the preparation of a standard solution.

Criteria of evaluation and of interpretation of Sepharose drug IgE-RIA to anaesthetic drugs

The detection of antidrug specific IgE in serum is usually performed by a sandwich-type immunoassay in which the serum IgE is first adsorbed to a reactive phase and subsequently quantified via the binding of an anti-IgE tracer. The preparation of a new drug-reactive phase requires one to establish carefully different steps of validation: 1) criteria of positivity of control sera 2) competitive inhibition assays with the soluble drug, which should include the determination of the inhibition constant rather than estimation of a single inhibition percentage, especially when the assay is performed for the identification of determinants 3) estimation of nonspecific binding of IgE to the solid phase, including hydrophobic binding. The competitive inhibition depends on the concentration of the competitor and of IgE in the test-tube and the concentration of reactive drug bound to the solid phase. We have improved the inhibition assay by performing the Dixon test for calculating the inhibition constant (Ki) of the competitor. The Ki of six different muscle relaxants was determined in 12 patients who experienced an anaphylactic reaction to muscle relaxants. The values ranged between 1.5 nM and 2.5 microM. This confirmed the great heterogeneity of drug IgE cross-reactivity among patients. The Ki value of the incriminated drug was the lowest (affinity, the highest) in eight of the 12 patients. It was better correlated to clinical data than the classical inhibition assay. A hydrophobic environment seemed to be necessary, close to the quaternary ion, to allow IgE binding to the muscle relaxant. By contrast, in tiemonium, a hydroxyl group present at a distance of about 3 A from the quaternary ion may explain why this molecule had a high Ki (microM). In conclusion, it should be recommended, in molecular-recognition studies, that the inhibition constant of the soluble drug and of the related compounds be determined to complement the experiments based only on hapten inhibition assays.

Anaphylactoid and anaphylactic reactions to iodinated contrast material

Some adverse reactions to iodinated contrast material (ICM) are considered allergy-like, with cutaneous, cardiovascular, respiratory, and digestive symptoms. Allergy-like reactions are usually unpredictable. Reactions are more frequent with ionic than with nonionic material, but the frequency of deaths is almost identical. In a recent study, 20 severe unexpected reactions to ICM, including 10 life-threatening reactions and one death, were investigated by measuring mediators in blood, within the first minutes or hours of reaction. The responsible ICMs were mostly ionic materials. Histamine and tryptase release correlated with the severity of the reaction. Specific IgE against the responsible ICM was significantly higher in reactors than in controls. A few patients had positive skin tests to the administered ICM, suggesting type-I allergic reaction. Only 2.4% and 3.1% of the cases yielded a positive IgE-RIA, in a second retrospective study which included 165 patients recruited during a 4-year period. In conclusion, IgE-mediated anaphylaxis is rare, but it may be one of the possible mechanisms of severe adverse reactions to ICM.

Concentrations of riboflavin and related organic acids in children with protein-energy malnutrition

BACKGROUND

Riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD) concentrations have been little studied in cases of malnutrition.

OBJECTIVE

Our objective was to investigate the effects of malnutrition on riboflavin status and riboflavin's relation with thyroid hormones and concentrations of urinary organic acids.

DESIGN

Malnourished children from the savannah in Benin (group S, n = 30) and the coast in Togo (group C, n = 30), as well as 24 control subjects from both regions, were studied. Blood riboflavin, FMN, and FAD were analyzed by HPLC; urinary organic acids were analyzed by gas chromatography-mass spectrometry.

RESULTS

Children in group S were more severely malnourished than children in group C. Triiodothyronine concentrations were lower in group S than in group C or the control group (1.12 +/- 0.24 compared with 1.74 +/- 0.18 and 2.92 +/- 0.19 nmol/L, respectively; P < 0.0001). Plasma riboflavin concentrations in group S were higher than those in group C or the control group (66.90 +/- 12.75 compared with 28.09 +/- 9.12 and 20.08 +/- 3.03 nmol/L, respectively; P < 0.001). Plasma FAD concentrations in group S were lower than those in group C or the control group (31.57 +/- 10.19 compared with 59.02 +/- 5.60 and 65.35 +/- 5.23 nmol/L, respectively; P < 0.0001). Dicarboxylic aciduria was higher in group C than in group S or the control subjects.

CONCLUSIONS

Children in group S had low triiodothyronine concentrations and low conversion of plasma riboflavin into its cofactors, leading to a plasma FAD deficiency. Plasma FAD was not correlated with urinary dicarboxylic acid concentrations.

Analysis of riboflavin and riboflavin cofactor levels in plasma by high-performance liquid chromatography

We describe an assay which determines simultaneously riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) in plasma, using galactoflavin (GF) as an internal standard. The flavins were extracted on a C18 Sep-Pack cartridge after protein precipitation with 10% trichloroacetic acid, and were analyzed on a C18 RP-HPLC with 85% phosphate-magnesium acetate buffer (pH 3.4) and 15% acetonitrile. FAD, FMN, GF and RF extraction recoveries were 101.0-5.6, 97.0-6.5, 97.0-2.0 and 95.0-4.1%, and reproducibilities were 5.9, 6.8, 2.1 and 4.3%, respectively. FAD, FMN and RF values in infant and adolescent plasma were in the range 53.5-108.2, 9.0-25.1 and 12.7-53.4 nM, and 36.5-157.20, 7.1-24.6 and 8.2-57.8 nM, respectively. Using GF as an internal standard improved the quantification of these B2 vitamers.

One-step purification of R-phycoerythrin from the red macroalga Palmaria palmata using preparative polyacrylamide gel electrophoresis

Phycoerythrin is a major light-harvesting pigment of red algae and cyanobacteria widely used as a fluorescent probe. In this study, phycoerythrin of the red macroalga Palmaria palmata was extracted by grinding the algal sample in liquid nitrogen, homogenisation in phosphate buffer and centrifugation. Phycoerythrin was then purified from this crude extract using preparative polyacrylamide gel electrophoresis (PAGE) with a continuous elution system and detected by its pink colour and fluorescence. The pigment presented a typical spectrum of R-phycoerythrin, with three absorbance maxima at 499, 545 and 565 nm, and displayed a fluorescence maximum at 578 nm. The absorbance ratio A565/A280, a criterion for purity, was 3.2. A single protein of relative molecular mass 240,000 was detected on native-PAGE with silver staining. Sodium dodecyl sulphate-PAGE demonstrated the presence of two major subunits with Mr 20,000 and 21,000, respectively, and a very minor subunit of Mr 30,000. These observations are consistent with the (alphabeta)6gamma subunit composition characteristic of R-phycoerythrin. Phycoerythrin of Palmaria palmata was determined to be present in larger amounts in autumn and showed a good stability up to 60 degrees C and between pH 3.5 and 9.5. In conclusion, phycoerythrin of Palmaria palmata was purified in a single-step using preparative PAGE. Obtaining pure R-phycoerythrin of Palmaria palmata will allow one to evaluate its fluorescence properties for future applications in biochemical techniques.

Influence of a high-calcium carbonate diet on the incidence of experimental colon cancer in rats

This study was done to determine whether a high dietary calcium carbonate concentration could protect against colon tumors in rats. Female Wistar rats were randomly assigned to one of four groups and maintained on an 8% lipid diet for an adaptation period of four weeks. All groups were then fed a 24% lipid diet (sunflower oil), with (Groups 2 and 4) or without (Groups 1 and 3) a 1.5% calcium carbonate supplement. They were intrarectally instilled with saline (Groups 1 and 2) or nitrosomethylurea (NMU) (Groups 3 and 4). Fecal sterol output and pH were analyzed for one week each month. Histological analysis was done at the end of the 32-week experiment. No tumors were found in the non-NMU-treated animals. The NMU-treated rats had tumors: 31% in Group 3 and 30% in Group 4. The calcium carbonate supplement had no effect on this incidence. The lipid and cholesterol excretions of the calcium carbonate-supplemented rats were significantly enhanced. The coprostanol output was not altered, although its fecal concentration of the calcium-supplemented rats was decreased. Although neither lipid overload nor NMU treatment altered the fecal pH, it was significantly increased in both calcium carbonate-supplemented groups. These findings suggest that additional calcium as carbonate has no effect on colon tumor incidence, although the fecal composition is altered. The increased pH of the feces due to the carbonate could have the opposite effect to calcium.

Diagnosis of lipid malabsorption in patients with chronic pancreatitis: a new indirect test using postprandial plasma apolipoprotein B-48

OBJECTIVE

This study was done to evaluate a new test for fat malabsorption caused by chronic pancreatitis. Postprandial plasma apolipoprotein B-48 was measured as an indicator of the intestinal assimilation of exogenous lipid.

METHODS

Twenty-three patients with chronic pancreatitis, including 19 insulin-treated diabetic patients, were compared with 14 healthy subjects and seven type-1 diabetic patients. Each was given a test meal containing 40 g lipid; the triglyceride apolipoprotein B-48 concentrations in chylomicrons were determined 240 min later.

RESULTS

The postprandial chylomicron apolipoprotein B-48 concentrations in the three groups were statistically different at 240 min: pancreatitis versus controls, p < 0.01, and pancreatitis versus type-1 diabetes subjects, p < 0.01. The delta plasma apo B-48, the change in apolipoprotein B-48 between 0 and 240 min, was significantly smaller in chronic pancreatitis patients than in controls (p < 0.001) and type-1 diabetes subjects (p < 0.001). The sensitivity of the test was better than 89% for a delta apo B-48 threshold value of 0.42 mg/dl.

CONCLUSIONS

This new indirect test is relatively simple to use and could be practical for evaluating exogenous lipid malabsorption due to chronic pancreatitis.

Comparison between serum alpha-glutathione S-transferase and aminotransaminases in detecting cytolysis in hepatitis C-infected children

BACKGROUND

alpha-Glutathione S-transferase (alphaGST) has been proposed as a more sensitive indicator than serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in detecting hepatocellular damage due to chronic hepatitis C virus (HCV) infection.

METHODS

The accuracy of alpha-GST was compared with that of ALT and AST in detecting cytolysis in 103 blood samples issued from 31 children positive for HCV RNA.

RESULTS

alpha-GST had a lower sensitivity than ALT or AST (32% vs. 54.4% for each aminotransferase). The sensitivity of ALT and/or AST was 60.2%, whereas that of ALT and/or alpha-GST and AST and/or alpha-GST was lower (58.3% and 57.3%, respectively). Among 41 serum samples with negative ALT and AST, only 2 had positive alpha-GST, whereas alpha-GST failed to detect cytolysis in 31 samples with elevated ALT and/or AST. No correlation was found between alpha-GST, ALT, or AST and the Knodell score.

CONCLUSIONS

The combination of ALT with AST is actually the best compromise in detecting cytolysis in untreated HCV-infected patients.

Riboflavin and riboflavin-derived cofactors in adolescent girls with anorexia nervosa

BACKGROUND

Thyroid hormones, riboflavin, riboflavin cofactors, and organic acids were assessed in girls with anorexia nervosa.

OBJECTIVE

The objective was to examine the effect of malnutrition and low thyroid hormone concentrations on erythrocyte and plasma riboflavin metabolism and their relation with urinary organic acid excretion.

DESIGN

Seventeen adolescent girls with anorexia nervosa [body mass index (BMI; in kg/m2): 14.8 +/- 2.2] and 17 age-matched, healthy girls (control subjects; BMI: 20.5 +/- 2.2) took part in the feeding study. Erythrocyte and plasma riboflavin as well as riboflavin cofactors (flavin mononucleotide and flavin adenine dinucleotide) were assessed by HPLC, whereas urinary organic acids were assessed by gas chromatography-mass spectrometry.

RESULTS

Anorectic patients who began a feeding program had higher erythrocyte riboflavin (3.5 +/- 2.2 compared with <0.1 nmol/mol hemoglobin; P < 0.001), lower plasma flavin adenine dinucleotide (57.8 +/- 18.5 compared with 78.5 +/- 54.3 nmol/L; P < 0.05), and higher urinary ethylmalonic acid (7.12 +/- 4.39 compared with 1.3 +/- 2.8 micromol/mmol creatinine; P < 0.001) and isovalerylglycine (7.65 +/- 4.78 compared with 3.8 +/- 0.9 micromol/mmol creatinine; P < 0.05) concentrations than did control subjects. Triiodothyronine concentrations were low and negatively correlated with plasma riboflavin concentrations (r = -0.69, P < 0.01). Not all patients showed improvements in these biochemical indexes after 30 d of refeeding.

CONCLUSIONS

The low triiodothyronine concentrations observed in anorexia nervosa could alter the extent of riboflavin conversion into cofactors, thus leading to high erythrocyte riboflavin concentrations, low plasma flavin adenine dinucleotide concentrations, and high rates of ethylmalonic acid and isovalerylglycine excretion.

C-Reactive protein and coronary artery disease: additional evidence of the implication of an inflammatory process in acute coronary syndromes

BACKGROUND

Inflammation might promote the development of atherosclerosis, and high levels of C-reactive protein (CRP) and fibrinogen are associated with an increased risk of acute coronary events.

OBJECTIVE

We assessed the levels of CRP and other risk factors in patients with angiographically documented coronary artery disease compared with healthy volunteers and patients undergoing coronary angiography who had normal coronary angiograms.

METHODS

Ultrasensitive immunoassay was used to measure CRP levels in 142 patients with coronary disease (group 1), 37 patients with normal coronary angiograms (group 2), and 37 control healthy subjects (group 3).

RESULTS

CRP levels were higher in group 1 (7.1 +/- 11.2 mg/L) compared with group 2 (4.8 +/- 4.0 mg/L) and group 3 (2.3 +/- 3.6 mg/L). In group 1, CRP levels were higher for patients with previous myocardial infarction (8.7 +/- 9.2 mg/L) or unstable angina (11.6 +/- 18.8 mg/L). Though CRP levels in patients with coronary artery disease and stable symptoms were higher compared with healthy volunteers (5.15 +/- 7.2 mg/L vs 2.3 +/- 3.6 mg/L, P <.05), they were similar to those observed in the control population of patients with normal coronary angiograms (4.8 +/- 4.0 mg/L). Furthermore, CRP levels were positively correlated to plasma fibrinogen but not to Chlamydia pneumoniae or Helicobacter pylori serology.

CONCLUSION

These results suggest that CRP has a strong association with acute coronary events but do not support the hypothesis that CRP is a potent determinant of chronic stable coronary disease.

Isoelectrofocusing phenotype and relative concentration of transcobalamin II isoproteins related to the codon 259 Arg/Pro polymorphism

We investigated transcobalamin II (TC) isoelectrofocusing (IEF) phenotype and codon 259 polymorphism, in Caco-2 and HT-29 cells and in blood drawn from 39 healthy Caucasians. Caco-2 cells expressed a single TC variant (259-Arg), while HT-29 cells expressed TC with either Arg or Pro at codon 259 and exhibited two isoproteins in IEF with urea, but only one in IEF without urea. Among the Caucasians, 7 subjects expressed the TC 259-Arg variant, 10 the 259-Pro variant, and 22 were heterozygous. The TC 259-Pro isoprotein issued from HT-29 cells and heterozygous caucasian sera, was, respectively, 2. 4-fold and 1.6-fold higher than the TC 259-Arg isoprotein. Apo-TC and vitamin B12 serum concentrations in 259-Pro homozygotes were, respectively, 1.7 and 1.4-fold higher than those in 259-Arg homozygotes (p<0.005 and p=0.05). In conclusion, the 259-Arg/Pro polymorphism yields two TC variants only titratable in denaturing conditions and affects the blood level of both Apo-TC and vitamin B12.

Mechanisms of severe, immediate reactions to iodinated contrast material

PURPOSE

To measure and elucidate the mechanisms of presumed mediators of unexpected severe, immediate reactions to iodinated contrast materials.

MATERIALS AND METHODS

In a multicenter study, 20 patients with mild to severe reactions to iodinated contrast material and 20 control subjects without reactions were evaluated. Ionic contrast material was associated with 18 (90%) of 20 reactions. Concentrations of plasma histamine, tryptase, urinary methylhistamine, specific immunoglobulin E (IgE) against ioxitalamate or ioxaglate, and the anaphylatoxins C3a and C4a were measured with radioimmunoassays; complement C3 and C4 levels were measured with nephelometry.

RESULTS

Histamine levels were increased in 14 patients; tryptase levels, in 16; and methylhistamine levels, in six. Histamine and tryptase values correlated with the severity of the reaction (P < .02 and P < .004, respectively). Significantly higher levels of specific IgE against ioxaglate (P < .005) and ioxitalamate (P = .045) were found in patients. No differences were found for complement fractions. Skin test results in two patients with life-threatening reactions were positive for the administered contrast material.

CONCLUSION

Histamine release and mast cell triggering are related to severe reactions. An IgE-related mechanism is strongly suspected. Radiologists should be trained to identify and treat anaphylactic shock in patients who react to iodinated contrast material.

Isolation and characterization of proteic allergens in refined peanut oil

Allergic reactions to peanut oil are very much debated, even if the responsibility of peanut oil has been evoked in several cases of adverse reactions, including death related to severe asthma. The aim of the present study was to investigate the presence of allergenic proteins in peanut oil. Proteins were extracted from commercial refined peanut oil, with a relative content in the order of 0.1-0.2 microg per g of oil, and molecular sizes ranging from 14 up to 76kDa in SDS-PAGE. Eight protein bands were systematically observed in crude, neutralized and refined oils, with a molecular mass ranging from approximately 14 to 76 kDa, including one at 18 kDa which was identified by Western blot performed with serum from two allergic patients. The protein extract gave positive IgE-RIA with patient sera, positive in vitro leucocyte histamine release tests and positive skin-prick tests in allergic patients. The allergenic protein was purified by HPLC and [125I] iodide-labelled. It had an isoelectric point at 4.5 in isoelectrofocusing. In conclusion, we have demonstrated the presence of allergenic proteins in crude and refined peanut oil. These proteins are the same size as two allergens previously described in peanut protein extracts.

Characterization of the oligomeric behavior of a 16.5 kDa peanut oleosin by chromatography and electrophoresis of the iodinated form

Oleosins are amphipathic proteins associated with oil bodies in seeds. We purified the major 16,500 peanut oleosin by preparative SDS-PAGE. Autoradiography after SDS-PAGE separation of the iodinated oleosin revealed covalently bound oligomers with Mr of 21,000, 33,000, 44,000 and 51,000. The strong capacity of these oligomers to form aggregates and to be incorporated into large-sized detergent micelles was demonstrated by gel permeation and isoelectric focusing. A 50% ethanol concentration was necessary to elute the 16,500 oleosin from octyl groups in hydrophobic interaction chromatography showing its natural tendency to interact with lipid acyl chains. This oligomerization behavior in aqueous solution is an indirect reflection of the interactions that occur in the oil body.

Evaluation of coupling of cobalamin to antisense oligonucleotides by thin-layer and reversed-phase liquid chromatography

We have evaluated by chromatography two strategies of oligonucleotide binding to vitamin B12 (cobalamin). The first one was based on a covalent linkage of aminooligonucleotide to carboxycobalamin in presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). Carboxycobalamin and EDC-cobalamin were eluted with a retention time of 16.5 and 21.6 min, respectively, in RP-HPLC, while aminooligonucleotide and oligonucleotide-cobalamin were coeluted at 19.4 and 19.8 min. In the second strategy, avidin was coupled to both biotinylated oligonucleotide and vitamin B12. Aminocobalamin and biotinylated cobalamin had respective retention times of 13 and 15.7 min in RP-HPLC and respective Rf values of 0.3 and 0.8 in thin-layer chromatography. Incubation of avidin with biotinylated cobalamin produced, in Superose 12 gel permeation, a peak with a retention time of 28 min, which corresponded to avidin-biotinylated cobalamin as it disappeared with an excess of either biotin or biotinylated oligonucleotide. In conclusion, we have prepared and purified by RP-HPLC and gel permeation chromatography an oligonucleotide-avidin-cobalamin complex which will be used as a vector complex of antisense oligonucleotides.

Purification of a 41 kDa cod-allergenic protein

Cod fish is one of the foods most frequently involved in allergy. Only the cod allergen Gad c I, a 12.3 kDa parvalbumin, has been purified and characterized. Recently, we have detected allergen bands which have not previously been described, in particular a 41 kDa protein, by Western-blot. In the present work, this protein has been purified from a crude cod extract by ammonium sulfate fractionation, hydroxyapatite chromatography and preparative electrophoresis; a single band with an Mr of 41 x 10(3) was found in silver-stained sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The amino acid composition and the isoelectric point of the protein were determined. The purified protein (p41) was shown to bind specifically to reaginic IgE from sera of cod-allergic individuals and to a monoclonal anti-parvalbumin which recognizes specifically the first calcium binding site of parvalbumins. p41 may therefore contain a calcium binding site corresponding to an IgE-epitope similar to that of Gad c I.