[Culture conditions for gametes and embryos: Which culture medium? Which impact on newborn?]

Many studies have examined the impact of cell/embryo culture media on the development of human embryo during IVF process, but few studies have followed up and compared the effects of these culture media on the developmental outcome of children conceived by IVF. As recurrent experimental evidence from animal studies suggests potential long-term effects of embryo culture media on the health outcome of IVF-conceived children, more studies are needed to clarify the role of the culture media and mechanisms underlying such effects. In human, however, the effects of culture media are difficult to pinpoint due to complications stem from both the influence of maternal nutrition during the gestational period and the parental genetic. Based on a simple review of the literature integrating animal experimentations and human clinic studies, we suggest that the composition of culture medium should be considered beyond the character of unique or sequential medium, corresponding to "let embryo choose" or "back to nature" respectively. Instead, we suggest that the main components of embryo culture media should be considered from the point of view of metabolic consequences and potential epigenetic effects. Given that energetic metabolites can regulate epigenetic machinery, we hypothesize that metabolic abnormalities linked to morphological abnormalities could reveal epigenetic defects in embryos.

Association of combined GIF290T>C heterozygous mutation/FUT2 secretor variant with neural tube defects

Folate and vitamin B12 are needed for the proper embryo-fetal development possibly through their interacting role in the 1-carbon metabolism. Folate fortification reduces the prevalence of complex birth defects, and more specifically neural tube defects (NTDs). GIF and FUT2 are 2 genes associated with the uptake and blood level of vitamin B12. We evaluated GIF and FUT2 as predictors of severe birth defects, in 183 aborted fetuses compared with 375 healthy newborns. The GIF290C allele frequency was estimated to 0.4% in healthy newborns and to 8.1% in NTD fetuses (odds ratio 17.8 [95% confidence interval CI: 4.0-77.6]). The frequency of FUT2 rs601338 secretor variant was not different among groups. The GIF 290C heterozygous/FUT2 rs601338 secretor variant combined genotype was reported in 6 of the 37 NTD fetuses, but not in other fetuses and healthy newborns (P < .0001). This GIF/FUT2 combined genotype has been previously reported in children with congenital gastric intrinsic factor (GIF) deficiency, with respective consequences on B12 binding activity and GIF secretion. In conclusion, a genotype reported in congenital GIF deficiency produces also severe forms of NTD. This suggests that vitamin B12 delivery to neural tissue by the CUBN/GIF pathway could play a role in the neural tube closure mechanisms.

A non-synonymous polymorphism in galectin-3 lectin domain is associated with allergic reactions to beta-lactam antibiotics

Genetic predictors of beta-lactam (BL) allergy are mostly related to Immunoglobulin E (IgE) synthesis and atopy. Despite this context, little attention has been devoted to genes of IgE/FcɛRI pathway, such as galectin-3, a β-galactoside-binding lectin, which binds to IgE. We evaluated the association of LGALS3 polymorphisms with BL allergy in 395 Spanish and 198 Italian cases, compared with 310- and 339-matched controls, respectively. The rs11125 predicted BL allergy with an odds ratio of 4.0 in Spanish population (P<0.0001). This association was replicated with an odds ratio of 5.1 in Italian population (P<0.0001); rs11125 predicted also increased serum level of total IgE in Spanish controls. These data are consistent with the predicted deleterious influence of Gln>His substitution produced by rs11125 on galactose-binding activity of galectin-3. In conclusion, LGALS3 is the strongest genetic predictor of BL allergy reported so far. This association reflects the influence of genes of IgE/FcɛRI pathway in this pathology.

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.

Genetic variants of the arachidonic acid pathway in non-steroidal anti-inflammatory drug-induced acute urticaria

BACKGROUND

To date, genetic studies of hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs) have been carried out mainly in aspirin-induced asthma and to a lesser extent in chronic urticaria, with no studies in patients with acute urticaria (AU), the most common entity induced by these drugs.

OBJECTIVE

In this work, we analysed the association of common variants of 15 relevant genes encoding both enzymes and receptors from the arachidonic acid (AA) pathway with NSAID-induced AU.

METHODS

Patients were recruited in several Allergy Services that are integrated into the Spanish network RIRAAF, and diagnosed of AU induced by cross-intolerance (CRI) to NSAIDs. Genotyping was carried out by TaqMan allelic discrimination assays.

RESULTS

A total of 486 patients with AU induced by CRI to NSAIDs and 536 unrelated controls were included in this large Spanish case-control study. Seven variants from 31 tested in six genes were associated in a discovery study population from Malaga (0.0003 ≤ p-value ≤ 0.041). A follow-up analysis in an independent sample from Madrid replicated three of the SNPs from the ALOX15 (rs7220870), PTGDR (rs8004654) and CYSLTR1 (rs320095) genes (1.055x10(-6) ≤meta-analysis p-value ≤ 0.003).

CONCLUSIONS AND CLINICAL RELEVANCE

Genetic variants of the AA pathway may play an important role in NSAID-induced AU. These data may help understand the mechanism underlying this disease.

Methotrexate for psoriasiform lesions associated with anti-tumour necrosis factor therapy in inflammatory bowel disease

BACKGROUND

Psoriasiform lesions associated with anti-tumour necrosis factor (TNF) therapy are frequent in patients with inflammatory bowel disease (IBD). While methotrexate is the most frequently used systemic treatment for psoriasis, its efficacy for psoriasiform lesions related to anti-TNF therapy remains unknown.

AIMS

To assess the efficacy of methotrexate for psoriasiform lesions associated with anti-TNF therapy refractory to topical therapy in IBD patients.

METHODS

The charts of eight patients from the Nancy IBD cohort who developed psoriasiform lesions on anti-TNF therapy were reviewed. Clinical response was defined as a decrease of more than 50% in the lesions covering surface. All patients were followed up by the same experienced dermatologist.

RESULTS

Eight women (seven Crohn's disease) were followed up for a median duration of 29 months (range, 20-45). Of the eight patients receiving methotrexate, three were primary responders without discontinuation of anti-TNF agents. Only one patient had a sustained response at final follow-up and was able to continue both methotrexate and anti-TNF therapy. Of the two other primary responders, one patient had to discontinue anti-TNF because of severe psoriasiform lesions, whereas the other one continued anti-TNF therapy despite persistent skin lesions at final follow-up. Among the five primary nonresponders, four patients had to stop anti-TNF treatment due to disabling skin lesions.

CONCLUSION

Methotrexate does not appear effective in treating psoriasiform lesions associated with anti-TNF therapy refractory to topical therapy in IBD.

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.

Meta-analysis: hyperhomocysteinaemia in inflammatory bowel diseases

BACKGROUND

The magnitude of association between homocysteine metabolism and inflammatory bowel diseases (IBD) remains unknown, whereas the association between hyperhomocysteinaemia and thrombosis remains controversial in IBD.

AIM

To conduct a systematic review and meta-analysis to examine these issues.

METHODS

The literature search was conducted using MEDLINE database and international conference abstracts from January 1966 to April 2011 and included all studies that evaluated plasma homocysteine level in IBD.

RESULTS

Twenty-eight studies evaluated the plasma homocysteine level and/or hyperhomocysteinaemia risk in IBD patients. Five studies assessed the association of hyperhomocysteinaemia with thrombosis. The mean plasma homocysteine level was significantly higher in IBD patients when compared with controls (weighted mean difference (WMD)=3.75 μmol/L; 95% CI, 2.23-5.26 μmol/L; P<0.0001; reference ranges for plasma homocysteine level: 5-12 μmol/L). The mean plasma homocysteine level did not differ between ulcerative colitis (UC) and Crohn's disease (CD) (WMD=0.41 μmol/L; 95% CI, -2.45 to 3.06 μmol/L; P=0.76). The risk of hyperhomocysteinaemia was significantly higher in IBD patients when compared with controls [odds ratio (OR)=4.65; 95% CI, 3.04-7.09; P<0.0001]. The risk of hyperhomocysteinaemia was not higher among IBD patients who experienced thromboembolic complications (OR=1.97; 95% CI, 0.83-4.67; P=0.12). Plasma folate level was inversely correlated with IBD risk associated with MTHFR C677T polymorphism (P=0.006).

CONCLUSIONS

The risk of hyperhomocysteinaemia is significantly higher in IBD patients when compared with controls. The risk assessment of hyperhomocysteinaemia-related thrombosis in IBD requires further investigation. Deficient folate status is associated with a higher impact of MTHFR C677T polymorphism on IBD risk.

Meta-analysis: hyperhomocysteinaemia in inflammatory bowel diseases

BACKGROUND

The magnitude of association between homocysteine metabolism and inflammatory bowel diseases (IBD) remains unknown, whereas the association between hyperhomocysteinaemia and thrombosis remains controversial in IBD.

AIM

To conduct a systematic review and meta-analysis to examine these issues.

METHODS

The literature search was conducted using MEDLINE database and international conference abstracts from January 1966 to April 2011 and included all studies that evaluated plasma homocysteine level in IBD.

RESULTS

Twenty-eight studies evaluated the plasma homocysteine level and/or hyperhomocysteinaemia risk in IBD patients. Five studies assessed the association of hyperhomocysteinaemia with thrombosis. The mean plasma homocysteine level was significantly higher in IBD patients when compared with controls (weighted mean difference (WMD)=3.75 μmol/L; 95% CI, 2.23-5.26 μmol/L; P<0.0001; reference ranges for plasma homocysteine level: 5-12 μmol/L). The mean plasma homocysteine level did not differ between ulcerative colitis (UC) and Crohn's disease (CD) (WMD=0.41 μmol/L; 95% CI, -2.45 to 3.06 μmol/L; P=0.76). The risk of hyperhomocysteinaemia was significantly higher in IBD patients when compared with controls [odds ratio (OR)=4.65; 95% CI, 3.04-7.09; P<0.0001]. The risk of hyperhomocysteinaemia was not higher among IBD patients who experienced thromboembolic complications (OR=1.97; 95% CI, 0.83-4.67; P=0.12). Plasma folate level was inversely correlated with IBD risk associated with MTHFR C677T polymorphism (P=0.006).

CONCLUSIONS

The risk of hyperhomocysteinaemia is significantly higher in IBD patients when compared with controls. The risk assessment of hyperhomocysteinaemia-related thrombosis in IBD requires further investigation. Deficient folate status is associated with a higher impact of MTHFR C677T polymorphism on IBD risk.

Additional benefit of procalcitonin to C-reactive protein to assess disease activity and severity in Crohn's disease

BACKGROUND

Serum procalcitonin level may reflect non-infectious inflammation.

AIM

To assess the correlation of serum procalcitonin level with clinical, biological, endoscopic and radiological markers of disease activity in inflammatory bowel diseases (IBD), and to evaluate the additional diagnostic benefit of measuring serum procalcitonin level to that of C-reactive protein (CRP) for disease activity appraisal.

METHODS

We performed a prospective observational study. Spearman's rank correlation and receiver operating characteristic analysis were used to evaluate correlation and diagnostic accuracy respectively.

RESULTS

In Crohn's disease (CD) (n = 30), serum procalcitonin level was strongly correlated with clinical, biological, endoscopic and radiological disease activity markers. In CD, the serum procalcitonin level >0.14 μg/L demonstrated a high accuracy for detecting severe disease (Sensitivity = 100%; Specificity = 96%; AUROC = 0.963; P = 0.0001). The diagnostic accuracy of the 'serum procalcitonin level-CRP strategy' (CRP >5 mg/L and serum procalcitonin level >0.05 μg/L) was significantly superior to that of CRP alone for diagnosing severe CD (AUROC = 0.783 vs. 0.674; P = 0.01). In ulcerative colitis (UC) (n = 27), serum procalcitonin level was correlated with CRP and with endoscopic and radiological disease activity markers.

CONCLUSIONS

In CD, the serum procalcitonin level was correlated with all disease activity markers and a cut-off of 0.14 μg/L could distinguish severe forms of the disease. The 'serum procalcitonin level-CRP strategy' was superior to CRP alone for diagnosing active or severe CD.

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.

Left ventricular systolic dysfunction is an independent predictor of homocysteine in angiographically documented patients with or without coronary artery lesions

BACKGROUND

Elevated plasma homocysteine is a risk factor for coronary artery disease (CAD) and thromboembolic disorders that seems also to be associated with chronic heart failure.

OBJECTIVE

To evaluate the association between homocysteine and left ventricular dysfunction and to assess whether it is independent of CAD.

PATIENTS AND METHODS

A prospective study evaluated this relationship in 709 patients referred for diagnostic coronary angiography, including 515 CAD and 194 patients without evidence of coronary artery lesions.

RESULTS

The homocysteine level was significantly higher in the 187 patients with a left ventricular ejection fraction (LVEF) dysfunction < 40% (P < 0.0001) than in those without ventricular dysfunction. LVEF, NYHA functional class II or III and CAD, stable angina and hypertension were clinical characteristics that influenced total homocysteine level in univariate analysis. Homocysteine was significantly associated with LVEF and N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) in univariate regression (r = -0.267, 95% CI -0.33 to -0.19, P < 0.0001, and r = 0.381, 95% CI 0.28-0.47, P < 0.0001, respectively) and in multiple regression (P = 0.0022 and P = 0.0001, respectively). Other determinants were creatinine and vitamin B(12), but not folate. LVEF was a predictor of homocysteine > 15 micromol L(-1) in the whole population (P for trend < or = 0.0001) and in patients without documented CAD (P for trend = 0.0058).

CONCLUSION

Our results showed an association of homocysteine with left ventricular systolic dysfunction and NT-pro-BNP that existed independently of documented CAD. Whether this association reflects a causative factor or a consequence of CHF and influences the prognosis of the disease remains an open question.

Association of tumor necrosis factor-alpha -308G>A polymorphism with IgE-mediated allergy to betalactams in an Italian population

Tumor necrosis factor-alpha (TNF-alpha) is released from mast cells via an immunoglobulin E (IgE)-dependent mechanism. The variant G>A at -308 of TNFA is part of an extended haplotype HLA-A1-B8-DR3-DQ2 and influences the gene expression. We evaluated this variant in relation to IgE-mediated reactions to betalactams, in 427 subjects, including 167 cases and 260 age- and gender-paired controls. TNFA GG genotype was a significant independent predictor of the primary risk of betalactam allergy, concurrently with total IgE level, with an age- and sex-adjusted odds ratio estimated at 2.45 (95% confidence interval: 1.18-5.08, P=0.0163). Cases with -308AA genotype had a higher serum level of specific IgE than those with -308GA/GG genotype, with median levels (relative units) of 4.6 (inter-quartiles: 3.9-10.6) and 2.2 (1.4-4.3), respectively (P=0.0046). In conclusion, our results suggest an ambivalent influence of a genetic determinant of pro-inflammatory pathways on IgE-mediated hypersensitivity to betalactams.

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.

Diagnosing immediate reactions to cephalosporins

BACKGROUND

After penicillins, cephalosporins are the betalactams that most often induce IgE-mediated reactions. The development of diagnostic tests has been delayed, however, because the cephalosporin allergenic determinants have not been properly identified.

OBJECTIVE

To evaluate the usefulness of skin tests, serum specific IgE assays, and challenges in diagnosing immediate reactions to cephalosporins and to clarify the pathogenic mechanism of such reactions.

METHODS

We studied 76 adults with immediate reactions to cephalosporins, mainly ceftriaxone, cefotaxime, and ceftazidime. Skin tests and serum specific IgE assays were performed for culprit cephalosporins and cefaclor, as well as for penicillin, amoxicillin, and ampicillin. Some subjects with negative results underwent challenges and re-evaluations. Responses to cephalosporins other than the culprit ones were also studied.

RESULTS

In the first allergologic work-up, an IgE-mediated hypersensitivity to penicillins and/or cephalosporins was diagnosed in 63 (82.9%) of the 76 patients on the basis of skin-test and/or specific IgE assay positivity. Of the 13 negative patients, eight accepted challenges and underwent re-evaluations. Considering both first- and second-evaluation results, the skin-test-positivity rate increased from 76.3% to 85.5% and that of sepharose-radioimmunoassay positivity from 67.1% to 74.3%. Overall, an IgE-mediated hypersensitivity was diagnosed in 70 patients (in seven after retesting). On the basis of skin-test and CAP-FEIA results, we classified our 76 patients into five groups: group A (three patients), positive only to penicillin reagents; B (17), positive to both cephalosporin and penicillin reagents; C (24), positive to more than one cephalosporin; D (21), positive only to the responsible cephalosporin; E (11) negative to skin tests and CAP-FEIA, including five sepharose-radioimmunoassay positive.

CONCLUSIONS

Most immediate reactions to cephalosporins appear to be IgE-mediated. Cephalosporin skin testing and sepharose-radioimmunoassay are useful tools for evaluating these reactions. Cephalosporin IgE-mediated hypersensitivity may be a transient condition; therefore, allergologic exams should be repeated in patients with negative initial allergologic work-ups, including challenges.

Mild, non-lesioning transient hypoxia in the newborn rat induces delayed brain neurogenesis associated with improved memory scores

Although neonatal hypoxia can lead to brain damage, mild hypoxic episodes may be beneficial, as illustrated by tolerance induction by preconditioning, a process that might involve neurogenesis. To examine if brief hypoxia in newborn rats could stimulate the generation of neurons, pups were exposed for 5 min to 100% N2. Cell density and apoptosis were monitored in various brain regions and cell proliferation was studied by the incorporation of bromodeoxyuridine. Hypoxia did not result in detectable cell death but promoted cell proliferation in the ensuing three weeks in the subventricular zone and hippocampal dentate gyrus, with increased cell density in hippocampus CA1 pyramidal cells and granular layer of the dentate gyrus. Newly generated cells expressed neuronal markers (NeuroD or neuronal nuclear antigen) and were able to migrate from germinative zones to specific sites, in particular from the subventricular zone to the CA1 layer along the posterior periventricle. Neurogenesis was associated with an early activation of the extracellular regulated kinase 1/2 pathway, and pre-hypoxic administration of U0126, an inhibitor of mitogen-activated protein kinase kinase, impaired hypoxia effect on cell proliferation. Neurobehavioral capacities of hypoxic rats paralleled those of controls, but early exposure to hypoxia was associated with significantly improved memory retrieval scores at 40 days. In conclusion, brief neonatal hypoxia may trigger delayed generation of potentially functional neurons without concomitant cell death. This may constitute an interesting model for studying cell key events involved in the induction of neurogenesis.

Homocysteine and related genetic polymorphisms in Down's syndrome IQ

OBJECTIVE

Down's syndrome (DS) is the most frequent genetic cause of Alzheimer-type dementia. Its metabolic phenotype involves an increased trans-sulphuration of homocysteine. The aim of the present study was to investigate the influence of homocysteinaemia (t-Hcys), folate, vitamin B(12), and related polymorphisms on intelligence quotient (IQ) in DS.

METHODS

The IQ of 131 patients with trisomy 21 from a specialist centre in Sicily was determined and classified according to DMS-IV. The effects of age, folate, vitamin B(12), t-Hcys, and genetic polymorphisms on IQ were evaluated separately and in combination using regression analyses.

RESULTS

IQ was significantly lower in DS patients with t-Hcys >7.5 micromol/l (median) and in those who were carriers of methylenetetrahydrofolate reductase (MTHFR) 677 T allele and of methylenetetrahydrofolate reductase 677 T and transcobalamin 776 G combined alleles (p = 0.0013, p = 0.0165, and p = 0.0074, respectively). The IQ correlated significantly with t-Hcys and folate in single and multiple regression analyses, independently of age. In addition, t-Hcys >9.6 micromol/l (upper quartile) was found to be associated with low IQ (<40, median of study group) with an odds ratio of 2.61 (p = 0.0203). The odds ratio was increased by threefold in carriers of MTHFR 677T allele. The MTHFR 677T allele/transcobalamin 776 G allele combination was associated with the risk of DS patients to have an IQ less that the median with an odds ratio of 2.68 (95% CI 1.26 to 5.70, p = 0.0104).

CONCLUSION

This study found evidence of an association between t-Hcys and MTHFR 677 T and transcobalamin 776 G alleles with IQ in patients with DS. The association may be related to a defective remethylation of homocysteine, affecting IQ.

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.

Association of IL-1 RN*2 allele and methionine synthase 2756 AA genotype with dementia severity of sporadic Alzheimer's disease

BACKGROUND

Genetic polymorphisms of APO-E, homocysteine, and the IL-1 gene cluster (IL-1A, IL-1B, receptor antagonist IL-1RN) are associated with sporadic Alzheimer's disease and may involve interdependent pathways of neuronal toxicity.

OBJECTIVE

To determine whether these polymorphisms and the genetic determinants of homocysteine (methylenetetrahydrofolate reductase, MTHFR; methionine synthase, MTR; transcobalamin, TC) are associated with an increased risk of severe dementia in Alzheimer's disease.

METHODS

152 patients with Alzheimer's disease and 136 controls were studied. The association of occurrence and dementia severity (Reisberg score <6 and >or=6) of Alzheimer's disease with APO-E, IL-1A, IL-1B, IL-1RN, MTHFR677 C-->T and 1298A-->C, MTR 2756 A-->G, and TC 776 C-->G polymorphisms was evaluated by multivariate logistic regression analysis after adjustment for age, sex, and age of onset of Alzheimer's disease.

RESULTS

IL-1A TT and IL-1B CT/TT associated genotypes were at risk of Alzheimer's disease (odds ratio 4.80 (95% confidence interval, 1.32 to 17.40), p = 0.017); the MTR 2756 AA genotype was at risk of severe dementia (OR 2.97 (1.23 to 7.21), p = 0.016); IL-1 RN*2 was protective (OR 0.28, (0.11 to 0.69), p = 0.006). Allele epsilon4 of the APO-E and IL-1B CC genotypes increased the risk of severe Alzheimer's disease associated with the MTR 2756 AA genotype by 3.3-fold and 1.5-fold, respectively.

CONCLUSIONS

Distinct determinants of the IL-1 gene cluster are related to the generation and progression of Alzheimer's disease. MTR only influences progression of the disease, which may be enhanced by carriage of allele epsilon4 of APO-E.

[Neural tube defects and vitamin B12: a report of three cases]

Periconceptional folic acid supplementation reduces the frequency of embryological neural tube defects (NTD). This fact led the USA to fortify grain products with folic acid (140 microg/100 g) starting in January 1998, with a resultant decrease in the incidence of NTD. Folate deficiency is thus confirmed to be a risk factor for NTD. However, in a prospective study, we investigated three women who conceived a fetus with NTD; no folate deficiency was found in these women but all three had decreased vitamin B12 levels (cobalamin), which can be an other risk factor. Samples were obtained from two women in Algeria, 2 days after interruption of pregnancy, and from a vegetarian woman, in France, one month after interruption of pregnancy. Red cell folate and plasma folate, vitamin B12, B6 and homocysteine were assayed and the mutations C677T (in metylenetetrahydrofolate reductase gene), A2756G (in methionine synthase gene) and A66G (in methionine synthase reductase gene) were sought. Elevated plasma folate levels were found in both Algerian women. Vitamin B 12 levels in all three women were decreased or in the lowest quartile of normal values. One woman presented simultaneously a vitamin B 12 deficiency, and heterozygous mutations in the three genes. The second woman presented a A66G homozygous mutation and the third heterozygous C677T and A66G mutations. Acquired and inborn factors are intricated in some cases of pregnancies with NTD and B 12 deficiency can be responsible for intracellular folate cycle failure. It would therefore be advisable to consider fortifying grain products with both folic acid and vitamin B12.

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.

A new oligomeric parvalbumin allergen of Atlantic cod (Gad mI) encoded by a gene distinct from that of Gad cI

BACKGROUND

The major allergen of Baltic cod (Gadus callarias) is a 12.3-kDa parvalbumin with two calcium-binding sites corresponding to EF-hand motifs. Our group found a 24-kDa IgE-reactive band that was also recognized by a monoclonal antiparvalbumin antibody in Atlantic cod (Gadus morhua). Our purpose was to purify and to determine the cDNA deduced sequence of this new cod allergen.

METHODS

Proteins from pre rigor mortis Atlantic cod were separated by gel filtration and the eluted peaks were analysed by SDS-PAGE and Western blotting with sera of sensitized patients and with antiparvalbumin. Protein bands were microsequenced, RNA transcripts were amplified by reverse transcription and polymerase chain reaction (RT-PCR) using primer combinations overlapping the open reading frame.

RESULTS

Four IgE and antiparvalbumin reactive proteins(12.5, 24, 38 and 51 kDa) were detected in gel filtration eluate. The cDNA deduced sequence of the 24 kDa protein had 109 amino acid residues with a molecular weight of 11.5 kDa and a theoretical pI of 4.34. The 24 kDa band corresponded therefore to a dimer of a beta-parvalbumin. Its homology was higher with Sal sI than with Gad cI. This new allergen was named Gad mI.

CONCLUSION

We have characterized a new parvalbumin allergen in Gadus morhua. This protein formed oligomers in native and in reducing conditions. Gad mI and Gad cI may correspond to two distinct genes of Gadus species.

The 18 kDa peanut oleosin is a candidate allergen for IgE-mediated reactions to peanuts

BACKGROUND

Peanut allergy is one of the five most frequent food allergies in children and in adults. Recently, we purified and evaluated the allergenicity of peanut oleosins, a family of small-sized proteins involved in the formation of peanut oil bodies.

METHODS

Allergenicity of the purified native protein and of the recombinant protein was tested by Western blot and by IgE-RIA.

RESULTS

We found IgE-binding with oleosin in 3 of 14 sera of patients who had suffered an allergic reaction to peanuts. Two sera reacted weakly against 16-18 kDa proteins corresponding to oleosin monomers, in Western blot. The main reacting bands had a molecular size estimated at approximately 34 kDa, approximately 50 kDa and approximately 68 kDa and could therefore correspond to oleosin oligomers. IgE reactivity was higher in extracts from roasted peanuts. The same phenomenon occurred with crude soybean oil fraction, with two bands of 16.5 and 24 kDa corresponding to monomers, and two bands of 50 kDa and 76 kDa corresponding to dimers and trimers, respectively. The 18 kDa band was observed in the 3 Western blots of a membrane-enriched fraction of recombinant oleosin produced in the Sf9-baculovirus expression system (performed with the 3 patient sera).

CONCLUSIONS

We have characterized a new peanut allergen which belongs to the oleosins, a family of proteins involved in the formation of oil bodies. The protein may be involved in some of the allergic cross-reactions to peanuts and soybeans.

The increased histamine release in ischaemic heart disease patients undergoing coronaroangiography is not mediated by specific IgE

BACKGROUND

The release of histamine by iodinated contrast media (ICM) is higher in coronary artery disease patients than in noncoronary patients during coronary angiogram.

METHODS

Eighty-eight patients who underwent a coronary angiography were classified either as having coronary artery disease or as noncoronary patients. Histamine concentration was higher than the 6.8 nM upper limit in 7 cases (group 1), of whom six were coronary artery disease patients. We compared the IgE and complement fractions in plasma of these patients to two control groups with normal histamine blood level, one (group 2) with and the other (group 3) without coronary artery disease.

RESULTS

No difference of total IgE and C(3c) and C(4) complement fractions was found among the three groups. Anti-ioxaglate IgE-RIA was positive in only one patient from group 1. The affinity of drug-IgE binding in the serum of this patient was very low (Kd: 18.7 mM). The level of anti-ICM IgE detected by ioxitalamate- and iomeprol-Sepharose RIA was significantly higher in groups 2 and 3 than in group 1.

CONCLUSIONS

The higher histamine release in ischaemic heart disease patients undergoing coronaroangiography is not mediated by IgE or complement activation. Further studies are needed to investigate the implication of histamine release factors.

IgE-binding and cross-reactivity of a new 41 kDa allergen of codfish

BACKGROUND

A 41-kDa IgE-reactive protein (p41) was purified from raw cod extract. This protein is homologous to an aldehyde phosphate dehydrogenase (APDH). The present study aims to evaluate the IgE-binding and the cross-reactivity of this protein in 13 patients allergic to codfish.

METHODS

IgE binding of sera from 13 patients allergic to codfish was tested by Sepharose RIA and by Western blot.

RESULTS

Among the 13 patients, only 4 had specific IgE to APDH detected by APDH-Sepharose RIA. The two patients who had the highest level of specific IgE to human APDH also had a class 5-6 CAP-RAST IgE level to codfish, but two other patients with a class 5 had a negative APDH-Sepharose IgE-RIA. Relative content of APDH was higher in extracts of commercial nonfrozen fish, compared to pre rigor mortis, post rigor mortis and frozen commercial codfish. A high homology of codfish APDH was found with the corresponding human enzyme. A significant inhibition of APDH-Sepharose by human and, to a lesser extent, by rabbit APDH was observed. Western blot of APDH codfish extract showed two bands at 41 and 36 kDa, respectively.

CONCLUSIONS

We have characterized a new allergen from codfish, which had a high level of homology in different species. The p41 relative content of extracts from nonfrozen codfish was higher than in the other samples assessed.

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.