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Biomedical subjects

S Frémont

Publications and source records attributed to S Frémont.

At least 19 recordsLinked to original sources
PubMed2003

Prospective study of mustard allergy: first study with double-blind placebo-controlled food challenge trials (24 cases).

BACKGROUND: Mustard allergy accounts for 1.1% of food allergies in children. However, double-blind placebo-controlled food challenge trials (DB PCFCs) have not yet been proposed. OBJECTIVE: To carry out DB PCFCs to determine the real frequency of mustard allergy in patients sensitized to mustard. METHODS: A prospective study was conducted in 30 subjects aged 3-20 years presenting positive prick tests to ground mustard seeds (Brassica nigra), mustard flour (B. juncea), metabisulfite-free strong mustard seasoning (B. juncea) and a commercialized allergenic extract (B. nigra). Twenty-seven subjects were screened for mustard-specific immunoglobulin E (IgE). PCFCs were carried out either DB or single blind (SB) with up to 1340 mg of metabisulfite-free seasoning. RESULTS: The mean diameter of the wheal induced by prick tests with the allergenic extract was lower (n.s.) than that induced by the native mustard products: 5.8 mm (1.5-15) vs 6.9 mm (0.5-18) for B. nigra ground seeds, 7.8 mm (1-20) for B. juncea flour and 9.7 mm (3-20) for the strong mustard seasoning. The diameter of the wheal induced by the allergenic extract was significantly different from that induced by the mustard seasoning (P < 0.005). The mean of mustard specific-IgE values was 8.7 KU/l (0.35-72.4). Seven of 30 food challenges were considered positive. Mean prick test results in the positive and negative PCFC subgroups were 5.5 mm vs 5.9 mm for the commercialized extract, 10.9 mm vs 5.8 mm for B. nigra ground seeds (P < 0.01), 9.9 mm vs 7.1 mm for B. juncea flour (n.s. P > 0.25) and 11.5 mm vs 9.1 mm for the metabisulfite-free mustard seasoning (n.s. P > 0.1). Mean specific IgE values determined by CAP system radioallergosorbent test (Phadebas Pharmacia) were higher but not significantly so (P > 0.25) in the subgroup with mustard allergy (12.3 K/l vs 7.6 KU/l). CONCLUSIONS: About 23.3% of the sensitized subjects were allergic to a routine dose of mustard. Positive prick tests and the presence of specific IgE were not predictive. SB PCFC or DB PCFC is required before recommending avoidance diets.

Abdominal Pain↗
PubMed2003

Laboratory tests for diagnosis of food allergy: advantages, disadvantages and future perspectives.

Numerous biological tests point to the diagnosis of food sensitization: detection of specific IgEs by Rast techniques, multi-detection assays, immunoblotting, screening of basophil activation (BAT or FAST), assays for leukotriene LTC4 release (CAST), measurement of plasma histamine, serum tryptase, serum ECP, urinary EDN, completed by mannitol-lactulose test evaluating intestinal permeability, assay of fecal IgEs, Rast for specific IgG4. Primary screening for anti-food IgEs by multi-detection assays seeks justification from insufficient clinical data and false positive tests are common in patients sensitized to pollens or latex, on account of in vitro cross reactivities (CR). Multiple CR explain positive Rast to vegetal food allergens in such patients. Biological tests should not be performed as the first line of diagnosis. In vivo sensitisation is assessed by positive prick-tests, demonstrating the bivalence of allergens, as well as the affinity of specific IgEs, two conditions necessary to bridge membrane bound specific IgEs, leading to the release of mediators. Prick-tests are closer to clinical symptoms than biological tests. However, the diagnosis of food allergy is based on standardised oral challenges. Exceptions are high levels of specific IgEs to egg (> 6 kUl/l), peanut (> 15 kUl/l), fish (> 20 kUl/l) and milk (> 32 kUl/l), reaching a 95% predictive positive value. Rast inhibition tests are useful to identify masked allergens in foods. Research developments will have impact on the development of new diagnostic tools: allergen mixes reinforcing a food extract by associated recombinant major allergens, multiple combination of recombinant allergens (chips) or tests with synthetic epitopes aimed a the prediction of recovery. Laboratory tests take place in the decision free for the diagnosis for the food allergy and the follow-up of the levels specific IgEs is a tool to assess outcome and contributes to predict recovery or persistent allergy. Up to now the significance of positive laboratory tests showing the implication of IgEs is at the crossroads of the allergist's and biologist's expertise.

Adult↗
PubMed2002

[Allergenicity of oils].

Cases of allergy to the oils of groundnut, sunflower, soya and sesame have been described in the literature. In parallel, other authors have affirmed that these oils are not allergenic. The objective of this article is to make the point on this question, to cite the procedures to which the seeds are submitted to extract the oil, to remember that the oils are not composed only of triglycerides and to describe the results of our work. Allergy of oils is a subject that is constantly submitted to controversy and the bibliography does not cease to give contradictory examples. This may be explained by the variations in extraction procedures used by the manufactures, as well as by the conditions of extraction of the proteins in the laboratory.

Allergens↗
PubMed2001

No correlation between wine intolerance and histamine content of wine.

BACKGROUND: Histamine is thought to be the main cause of adverse reactions to wines. OBJECTIVE: The purpose of this study was to test the hypothesis that the level of histamine in wine affects the tolerance to wine in 16 subjects with wine intolerance. METHODS: We performed a study to examine the effects of wine histamine content in 16 adults with wine intolerance. Each subject underwent 2 double-blind provocation tests with wine: 1 with a wine poor in histamine (0.4 mg/L), and 1 with a wine rich in histamine (13.8 mg/L). Blood was collected for histamine and methylhistamine RIAs at 0, 10, 30, and 45 minutes after ingestion of the wine. Methylhistamine and methylimidazolacetic acid (gas chromatography and mass spectrometry) were measured in urine 5 hours before and 5 hours after ingestion. RESULTS: No significant differences in the occurrence of adverse reactions were noted after ingestion of either of the wines (McNemar test). At 10 minutes, a significant increase was observed in plasma histamine with histamine-poor wine. No significant changes (Wilcoxon test) were observed in the methylhistamine and methylimidazolacetic acid levels after ingestion of either histamine-poor or histamine-rich wine. CONCLUSION: This study demonstrates that there is no correlation between the histamine content of wine and wine intolerance. The increase of plasma histamine levels at 10 minutes with histamine-poor wine suggested the role of a histamine-releasing substance. The role of acetaldehyde is discussed.

Adult↗
PubMed2000

The effect of 677C-->T and 1298A-->C mutations on plasma homocysteine and 5,10-methylenetetrahydrofolate reductase activity in healthy subjects.

We have studied the effect of common mutations (677C-->T and 1298A-->C) of the methylenetetrahydrofolate reductase (MTHFR) gene in sixty-six healthy French subjects, aged 27-47 years. Serum folate, vitamin B12, and plasma total homocysteine were measured as well as the specific activity of MTHFR in lymphocytes. The frequency of subjects homozygous for the 677TT genotype was 18%, and that of those homozygous for the 1298CC genotype was 12.5%. The frequency of individuals heterozygous for both mutations was 23.5%. The 1298A-->C mutation was associated with decreased MTHFR specific activity in subjects with both 677CC and 677CT genotypes. This activity was 60% for the 677CC/1298AC genotype and 52% for the 677CC/1298CC genotype when compared with the MTHFR specific activity of the 677CC/1298AA genotype. Heterozygotes for both mutations (677CT/1298AC genotype) had 36% of the reference specific activity. Although homocysteine levels in 677TT and 1298CC genotype subjects were higher than for other genotypes, no significant differences were observed among different genotypes. This may be due to high serum folate level in our samples, and suggests that folate therapy may be useful to prevent hyperhomocysteinaemia in homozygous mutant subjects.

5,10-Methylenetetrahydrofolate Reductase (FADH2)↗
PubMed1999

Cross-allergenicity of peanut and lupine: the risk of lupine allergy in patients allergic to peanuts.

BACKGROUND: Peanut allergy is common, but cross-allergy between legumes is rare. Proteins from Lupinus albus are increasingly eaten in the form of seeds or additives to wheat flour. The risk of cross-allergenicity is still insufficiently known. OBJECTIVE: We sought to study the risk of cross-allergy to lupine in patients allergic to peanut and to study lupine allergenicity. METHODS: Twenty-four patients allergic to peanuts were studied by means of skin prick tests with native lupine flour from Lupinus albus. Double-blind oral challenge tests were performed with lupine flour and peanut in 8 of these patients. Specific IgEs were assayed for peanut, lupine flour, and pollen in 6 sera. RAST inhibition tests for lupine pollen by peanut were performed on 4 of these sera. Peanut and lupine flour immunoblots were carried out for 6 sera, and crossed immunoblot inhibitions for peanut by lupine flour and lupine flour by peanut were carried out for 2 sera. RESULTS: The skin prick test responses with lupine flour were positive in 11 (44%) subjects. The challenge test responses were positive in 7 of 8 subjects at the same doses as with peanut. The major lupine flour allergen (molecular mass, 43 kd) is present in peanuts. The RAST inhibition and immunoblot tests indicated cross-reactivity of peanut with the lupine flour and pollen. CONCLUSIONS: The risk of crossed peanut-lupine allergy is high, contrary to the risk with other legumes. The inclusion of 10% lupine flour in wheat flour without mandatory labeling makes lupine a hidden allergen, presenting a major risk of cross-reaction in subjects already allergic to peanut products. A high sensitizing potential can also be postulated for this legume.

Adolescent↗
PubMed1999

Human basophil activation measured by CD63 expression and LTC4 release in IgE-mediated food allergy.

BACKGROUND: IgE-dependent basophil activation induced by an allergen elicit the release of LTC4 and the expression of the CD63 membrane marker. OBJECTIVE: The aim of this study was to check if flow cytometric analysis of basophil activation could be applied to food allergy diagnosis and if this method paralleled LTC4 release. METHODS: Patients were selected by the clinical history, skin tests, and provocation tests. Basophil activation induced by food extracts was studied in 24 control subjects and in 27 patients having a food allergy by LTC4 release test (LRT) and by flow cytometric anti-IgE+, CD63 + cell counting (BAT = basophil activation test). In case of negative anti-IgE response a passive blood donor basophil passive sensitization step was added to LRT and BAT. Leucocyte histamine release test was performed in 11 patients. RESULTS: Basophil activation test was positive in 18/31 cases and LRT in 22/34 cases for food-allergic patients and, respectively, in 1/33 and 1/35 cases for the controls. A correlation was observed between specific IgE, BAT, and LRT. Basophil activation test and LRT performed after passive sensitization had an excellent sensitivity only for specific IgE levels ranging between 3.5 and 35 KU/L. CONCLUSION: The present study shows that allergen-induced LTC4 release and anti-IgE, antiCD63 bicolor flow cytometric analysis of basophil activation may be used for food allergy diagnosis. Both tests have a good sensitivity and specificity. Basophil activation test and LRT are more efficient than histamine release test in case of high spontaneous histamine release, frequently observed in case of food allergy.

Adolescent↗
PubMed1999

Histamine content does not influence the tolerance of wine in normal subjects.

Histamine has been incriminated as having a responsibility for intolerance reaction to wines. We have made a study by double blind oral provocation test to find the effect of ingestion of a histamine-rich (22.8 mg.l-1) and a histamine free wine in eight healthy subjects. Blood samples were taken at 0, 10, 30 and 45 minutes after ingestion of the wine for measurement of plasma histamine and methylhistamine. Urines were collected 5 hours before and 5 hours after ingestion for measurement of urinary methylhistamine. No subject presented a reaction of intolerance after ingestion of wine rich or poor in histamine. No change in plasma histamine and plasma and urinary methylhistamine was seen. This study shows that the amount of histamine in wine has no clinical or biological effect in healthy subjects, and this emphasized the efficiency in man of the systems for degradation of histamine that is absorbed by the alimentary tract.

Adult↗
PubMed1999

[Measurement of levels of specific IgE by the Efficient New Enzymatic Allergy (ENEA) System II (CIS bio)].

The diagnosis of IgE dependant food allergy relies on the demonstration of specific IgE by prick tests or in vitro tests. The ENEA System II (CIS bio international) is a new automatic assay analyser of specific IgE, that uses allergens coupled to a solid phase and a urease marked anti-IgE antibody. This study aims to compare the performance of the ENEA System II to that of Pharmacia CAP System for the assay of food specific IgE (milk, eggs, peanuts) by means of unit tests and multitests. Sixty three patients were included: 10 non atopic controls, 19 egg-allergic patients, 10 patients allergic to cow's milk, and 24 patients allergic to peanuts. The food allergy was proved by means of a double blind oral, labial or bronchial challenge and/or effective avoidance of the food. For both systems, the specificity of unit tests was 100%. Sensitivity was 60% and 100% with both systems, using milk and peanuts respectively. However, using eggs, it was only 74% with ENEA System II versus 95% with Pharmacia CAP System. The intra-trial variation coefficients were comparable. In contrast, inter-trial variation coefficient was very high for the ENEA System II (20.3% versus 7.3%). The multitest named "children's food" showed an important inter-set variability. In conclusion, the ENEA System II is a rapid automatic tester whose performance has to be improved. The actual thermostatically control of the system was shown to achieve quality assay. The conservation of the solid phase, recently perfected, is expected to suppress the inter-set variability.

Adult↗
PubMed1997

Prevalence of lysozyme sensitization in an egg-allergic population.

An egg protein, lysozyme, is a still unlabeled additive currently used in cheese preparation. Furthermore, the WHO-FAO committee considers it innocuous. However, 31% of children and 8% of adults with food allergies are allergic to eggs. This work aimed to determine the percentage of patients sensitized to lysozyme from a population of egg-allergic patients. Specific IgE was determined with Cap RAST in 52 patients clinically allergic to egg. Thirty-five percent of egg-allergic patients had antilysozyme IgE. Given this high incidence of lysozyme sensitization, it seems that the presence of lysozyme should be indicated on food labels.

Administration, Oral↗
PubMed1996

Identification of a masked allergen, alpha-lactalbumin, in baby-food cereal flour guaranteed free of cow's milk protein.

We report on a baby food, cereal flour P (CFP), which, although guaranteed free of cow's milk protein, caused failure to thrive and diarrhea, vomiting, and coughing fits in a 22-month-old child. The purpose of this study was to identify the allergen involved. The investigation used prick tests, RAST, and the RAST inhibition method. Specific IgE was elevated to 100 kU/l for cow's milk and to 15.3 kU/l for alpha-lactalbumin (2.5 kU/l for casein, 0.7 kU/l for beta-lactoglobulin). Antibovine IgG IgEs were associated. RAST inhibition experiments demonstrated the presence of alpha-lactalbumin in "food-quality" lactose used in this flour, at a dose of 1-5 micrograms/g of CFP. The daily intake of alpha-lactalbumin was found to be less than 70 micrograms. This exquisite clinical sensitization was attributed to the intestinal hyperpermeability (IH) which favors the access of milk allergen to the blood, leading to an ever-growing state of hypersensitivity. It could have been due to egg- and mustard-associated allergies as well as to giardiasis and intestinal candidosis. This work underlines the risk of masked food allergens and the need of thoroughly informative labeling.

Allergens↗
PubMed1996

[Influence of visible interferences on biochemical assays realised on Au 5231, AU 5223 (Olympus) and CL 7200 (Shimadzu)].

The impact of the major interferents (hemolysis, bilirubin, turbidity), on the quality of biochemical tests, was evaluated on multiparametric analysers (CL 7200 Shimadzu, Japan/Ciba-Corning, France; AU 5231 and AU 5223 Olympus, Japan/bioMérieux, France), according to the SFBC instructions. Interferences were detected in 33 cases upon 165 tests realized, that is to say 20% of the performed analysis. Turbidity was the most frequent cause of interference (7.8%), followed by hemolysis (8.5%) and bilirubin (3.6%). The use of a sample blank, a bireagent, the change of reagent, the change of the secondary wavelength or the modification of the measurement times, allowed us to reduce more than 80% of the interferences. Only three interferences remained: hemolysis upon the measurement of TGO and potassium, and bilirubin upon the measurement of creatinine. For these parameters, a suitable note using the Olympus factors (semi quantitative expression of the importance of the three interferents) is reported on the answer sheet.

Animals↗
PubMed1995

The use of two multitests fx5 and fx10 in the diagnosis of food allergy in children: regarding 42 cases.

The multitests Cap RAST fx5 and fx10 (Pharmacia, Cap System) are used for a rapid biological diagnosis of food allergy. These tests were assessed in 29 children who presented 42 food allergies (FA) documented by prick tests, specific IgE and labial or oral provocation tests (single blind placebo controlled food challenges). When the multitests were positive, the search for specific IgE to the corresponding allergens was performed (Cap RAST, Pharmacia). The theoretical coverage of FA could be estimated according to the frequency of food allergens involved in the children. It reaches 85% for Cap RAST fx5 and 29% for Cap RAST fx10. The sensitivity of Cap RAST fx5 is 89% and 50% for Cap RAST fx10. Even in the case when the child had a single food allergy, the detail of specific IgE showed multiple positivities to several allergens included in the multitest. Consequently, the positive predictive value of Cap RAST was only 32%. Prick tests to the same allergens were more rarely positive, gaining thus a better positive predictive value. The authors propose the use of Cap RAST fx5, eventually completed by a Cap RAST to beef for the first approach of food allergy in children. They stress the point that prick tests have to be carried on subsequently, in order to select properly allergens responsible for food allergy.

Adolescent↗