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Biomedical subjects

A Mari

Publications and source records attributed to A Mari.

At least 19 recordsLinked to original sources
PubMed2006

Restoration of normal glucose tolerance in severely obese patients after bilio-pancreatic diversion: role of insulin sensitivity and beta cell function.

AIMS/HYPOTHESIS: The aim of this study was to analyse the mechanisms underlying the improvement in glucose tolerance seen in morbidly obese patients undergoing bilio-pancreatic diversion (BPD). SUBJECTS AND METHODS: We evaluated glucose tolerance (by OGTT), insulin sensitivity (euglycaemic-hyperinsulinaemic clamp and the OGTT index OGIS) and beta cell function (OGTT modelling analysis) in 32 morbidly obese (BMI=52+/-7 kg/m(2), mean+/-SD) patients (12 with NGT, 9 with IGT and 11 with type 2 diabetes), before and after BPD, and in 22 lean control subjects. Patients were studied before and from 7 days to 60 months after surgery. RESULTS: BPD improved glucose tolerance in all subjects, who after surgery all had normal glucose tolerance. Insulin sensitivity was restored to normal levels in all subjects (pre-BPD 341+/-79 ml min(-1) m(-2), post-BPD 511+/-57 ml min(-1) m(-2), lean 478+/-49 ml min(-1) m(-2)). The insulin sensitivity change was detectable within 10 days of BPD. At baseline, beta cell sensitivity to glucose was impaired in diabetic subjects (25 [18] pmol min(-1) m(-2) l mmol(-1), median [interquartile range]) compared with lean subjects (82 [98]; p</=0.05). After BPD, beta cell glucose sensitivity showed a tendency towards improvement but remained impaired in diabetic subjects (30 [62]; p<0.01 vs lean). Total insulin output decreased in parallel with the insulin sensitivity increase in all groups. In the whole patient group, mean OGTT glucose levels were inversely related to both insulin sensitivity and beta cell glucose sensitivity (r (2)=0.67, partial r=-0.76 and -0.41, respectively). NEFAs, leptin and adiponectin were related to insulin sensitivity but could not explain the early improvement. CONCLUSIONS/INTERPRETATION: Following BPD, glucose tolerance was restored mainly as a result of a rapid and large improvement in insulin sensitivity.

Adiponectin↗
PubMed2006

Mathematical modeling shows exenatide improved beta-cell function in patients with type 2 diabetes treated with metformin or metformin and a sulfonylurea.

The incretin mimetic exenatide improved glycemic control and reduced body weight in patients with type 2 diabetes inadequately controlled with metformin+/-a sulfonylurea. We assessed postprandial beta-cell function by mathematical modeling, independent of confounding effects from differing ambient glucose levels among treatments. Subjects were 63% males, 55+/-10 years, BMI 33+/-6 kg/m2, HbA1C 8.1+/-1.1% (+/- SD) randomized to 5 microg exenatide or placebo twice daily for 4 weeks. Subsequently, one arm remained at 5 microg twice daily, one arm escalated to 10 microg twice daily, and one treatment arm remained on placebo for 26 weeks. Subjects continued metformin+/-a sulfonylurea. A subset with meal tests at baseline and week 30 were analyzed (n=73). Outcome measures were the model-based beta-cell function parameters dose-response relating insulin secretion to glucose concentration, rate sensitivity, and potentiation. Exenatide reduced postprandial glucose excursions. Modeling predicted an upward shift of the beta-cell dose-response. Model-predicted insulin secretion rate at a reference glucose concentration increased 72% (10 microg), increased 40% (5 microg), or decreased 21% (placebo) at week 30 [ p=0.015 (10 microg); p=0.045 (5 microg); vs. placebo]. At week 30, the 2-hour post-meal to basal potentiation factor ratio was increased to 1.53+/-0.10 (10 microg; p=0.0142 vs. placebo) or 1.40+/-0.08 (5 microg; p=0.0402 vs. placebo) compared with 1.15+/-0.06 (placebo). Exenatide caused an upward shift of the beta-cell dose-response and enhanced potentiation of insulin secretion. This model suggests exenatide improved beta-cell function in patients with type 2 diabetes treated with metformin+/-a sulfonylurea.

Adult↗
PubMed2006

Natural and recombinant molecules of the cherry allergen Pru av 2 show diverse structural and B cell characteristics but similar T cell reactivity.

BACKGROUND: Cherry allergy is often reported in the context of allergy to other fruits of the Rosaceae family and pollinosis to trees because of cross-reactive allergens. Allergic reactions to cherry are reported by 19-29% of birch pollen-allergic patients. Pru av 2, identified as a thaumatin-like protein (TLP) from sweet cherry, was recognized by the majority of cherry-allergic patients in immunoblotting. OBJECTIVES: In order to investigate the structural characteristics and the immunoglobulin (Ig)E- and T cell reactivity of cherry-derived TLP, recombinant Pru av 2 was expressed in Escherichia coli and natural Pru av 2 was purified. METHODS: Parallel-His and FLAG expression vectors were used for recombinant production of Pru av 2 in the cytoplasm and the periplasm of E. coli. Natural Pru av 2 was purified from fresh cherries and verified by N-terminal sequencing. Structural characterization was performed using circular dichroism (CD) measurements, and the biologic activity was measured in a glucanase assay. Using cherry-specific sera, the IgE-binding ability of recombinant and natural Pru av 2 was investigated in IgE-ELISA and the T cell reactivity was studied in proliferation assays. Results Natural Pru av 2 revealed thaumatin-like structural features and bound IgE of 50% of cherry-allergic patients. It was demonstrated to be enzymatically active. Recombinant Pru av 2 expressed in the cytoplasm of E. coli exhibited a slightly different folding compared with the natural protein. It was not recognized by IgE from cherry-allergic subjects, but retained the ability to stimulate T lymphocytes. Periplasmic recombinant Pru av 2 was able to bind an anti-grape TLP antibody and cherry-specific IgE. CONCLUSIONS: We prepared two recombinant model TLPs from cherry, and compared their molecular characteristics as well as their IgE-binding activity and T cell interactions in relation to the natural counterpart. The cytoplasmic recombinant Pru av 2 can be used as a hypoallergenic variant in allergen-specific immunotherapy, whereas the periplasmic protein can be included in a component-resolved diagnosis.

Adult↗
PubMed2006

Alternaria alternata NADP-dependent mannitol dehydrogenase is an important fungal allergen.

BACKGROUND: Alternaria alternata is one of the most important allergenic fungi worldwide. Mannitol dehydrogenase (MtDH) has previously been shown to be a major allergen of Cladosporium herbarum and cross-reactivity has been demonstrated for several fungal allergens. OBJECTIVE: The present study's objective was to clone the MtDH from an A. alternata cDNA library, express and purify the recombinant non-fusion protein and test its IgE-binding properties. Methods A cDNA library prepared from A. alternata hyphae and spores was screened for mannitol dehydrogenase by DNA hybridization with the radioactively labelled C. herbarum homologue as a probe. The resulting clone was sequenced and heterologously expressed in Escherichia coli as a recombinant non-fusion protein, which was purified to homogeneity and analysed for its IgE-binding capacity. RESULTS: The coding sequence of the full-length cDNA clone comprises 798 bp encoding a protein with a molecular mass of 28.6 kDa and a predicted pI of 5.88. Protein sequence analysis revealed an identity of 75% and a homology of 86% between the MtDHs of A. alternata and C. herbarum. The functional mannitol dehydrogenase was expressed in the E. coli strain BL21(DE3) transformed with the vector pMW172 and purified to homogeneity. The enzyme catalyses the NADPH-dependent conversion of d-fructose to d-mannitol. In IgE-ELISA and immunoblots, MtDH is recognized by 41% of A. alternata-allergic patients. In vivo immunoreactivity of the recombinant MtDH was verified by skin prick testing. Finally, inhibition-ELISA experiments confirmed cross-reactivity between the MtDHs of A. alternata and C. herbarum. CONCLUSION: Mannitol dehydrogenase (Alt a 8) represents an important new allergen of the ascomycete A. alternata that might be suitable for improving diagnostic and therapeutic procedures.

Allergens↗
PubMed2006

Impaired beta-cell function in lean normotolerant former gestational diabetic women.

BACKGROUND: Former gestational diabetes (fGDM) constitutes a risk condition for the development of Type 2 diabetes. Former gestational diabetes is often characterized by obesity and hyperglycaemia, which may be concomitant and independent risk factors. MATERIALS AND METHODS: To assess insulin sensitivity and beta-cell function in fGDM uncomplicated by obesity and hyperglycaemia, we studied 24 lean fGDM women and 23 control women matched for age (30.7 +/- 0.7 years, whole cohort), body mass index (22.2 +/- 0.3 kg m(-2)), and indistinguishable for plasma glucose both at fasting and at 120 min. Several insulin sensitivity and beta-cell function indices were computed: homeostasis model assessment insulin resistance index (HOMA-R), insulin sensitivity index derived from an oral glucose tolerance test (OGIS), insulinogenic index, other empirical indices of insulin secretion and beta-cell function, and indices obtained using a beta-cell model. RESULTS: Though the majority of indices, and in particular insulin sensitivity (HOMA-R: 1.35 +/- 0.13 vs. 1.65 +/- 0.14; OGIS: 492.7 +/- 6.3 vs. 496.4 +/- 9.4 mL min(-1) m(-2)), were not significantly different in the two groups, the beta-cell glucose sensitivity obtained by modelling analysis was lower in fGDM (108 +/- 14 vs. 165 +/- 22 pmol min(-1) m(-2) mM(-1), P = 0.031). CONCLUSIONS: Impairment of beta-cell glucose sensitivity may be an intrinsic risk factor in fGDM independently of obesity and hyperglycaemia. Furthermore, we have shown that modelling analysis, in contrast to the empirical parameters, may be able to detect early beta-cell alterations in fGDM women.

Adult↗
PubMed2005

Impaired beta cell glucose sensitivity and whole-body insulin sensitivity as predictors of hyperglycaemia in non-diabetic subjects.

AIMS/HYPOTHESIS: The aim of this prospective study was to investigate predictors of deteriorating glucose tolerance in subjects of British extraction. METHODS: A total of 156 non-diabetic subjects (86 with a family history of type 2 diabetes) underwent a 75-g OGTT and anthropometric assessment at baseline and 5 years later. Pancreatic beta cell function and whole-body insulin sensitivity were studied by model assessment. Subjects were classified as progressors if glucose tolerance moved one or more steps from normal, impaired fasting glucose, impaired glucose tolerance and diabetes over the follow-up period. RESULTS: At baseline, the progressors (n=22) had increased adiposity and a higher proportion of familial diabetes and abnormal glucose tolerance than non-progressors. Baseline pancreatic beta cell sensitivity to changes in glucose (p<0.02) and whole-body insulin sensitivity (p<0.0001) were decreased in the progressors. Logistic regression revealed that baseline and follow-up changes in beta cell glucose sensitivity and insulin sensitivity, rather than the classical clinical predictors (adiposity, familial diabetes and glucose levels), were the key independent predictors of progression (explaining over 50% of the progression). CONCLUSIONS/INTERPRETATION: Impaired pancreatic beta cell glucose sensing and whole-body insulin sensitivity predict progression to hyperglycaemia. Strikingly, these pathophysiological changes override the importance of the clinical risk factors and highlight potential metabolic targets for prevention strategies.

Adult↗
PubMed2005

Visceral fat and beta cell function in non-diabetic humans.

AIMS/HYPOTHESIS: Preferential visceral adipose tissue (VAT) accumulation has been clearly associated with insulin resistance. In contrast, the impact of visceral obesity on beta cell function is controversial. METHODS: In 62 non-diabetic women and men (age 24-69 years, BMI 21-39 kg/m2), we measured VAT and subcutaneous adipose tissue (SAT) fat mass by magnetic resonance imaging. We also measured insulin secretion and beta cell function by C-peptide deconvolution and physiological modelling of data from a frequently sampled, 75-g, 3-h OGTT, respectively. RESULTS: VAT (range 0.1-3.1 kg) was strongly related to sex, age and BMI; SAT was related to sex and BMI. Controlling for sex, age, BMI and SAT by multivariate analysis, excess VAT was associated with a clinical phenotype comprising higher plasma glucose levels, BP, heart rate and serum transaminases. The corresponding metabolic phenotype consisted of insulin resistance (partial r=-0.38) and hyperinsulinaemia (partial r=0.29). The latter, however, was appropriate for the degree of insulin resistance regardless of obesity and abdominal fat distribution. Moreover, none of the model-derived parameters describing beta cell function (glucose sensitivity, rate sensitivity and potentiation) was independently associated with excess VAT. CONCLUSIONS/INTERPRETATION: In non-diabetic Caucasian adults of either sex, preferential visceral fat deposition in itself is part of an insulin-resistant phenotype. The insulin secretory response to a physiological challenge is increased to fully compensate for the insulin resistance, but the dynamics of beta cell function (glucose sensitivity, rate sensitivity and potentiation) are largely preserved.

Adipose Tissue↗
PubMed2005

Vildagliptin, a dipeptidyl peptidase-IV inhibitor, improves model-assessed beta-cell function in patients with type 2 diabetes.

AIMS/HYPOTHESIS: The dipeptidyl peptidase IV inhibitor, vildagliptin, increases levels of intact glucagon-like peptide-1 (GLP-1) and improves glycemic control in patients with type 2 diabetes. Although GLP-1 is known to stimulate insulin secretion, vildagliptin does not affect plasma insulin levels in diabetic patients, suggesting that more sophisticated measures are necessary to ascertain the influence of vildagliptin on beta-cell function. METHODS: This study examined the effects of 28-d treatment with vildagliptin (100 mg, twice daily; n = 9) vs. placebo (n = 11) on beta-cell function in diabetic patients using a mathematical model that describes the insulin secretory rate as a function of glucose levels (beta-cell dose response), the change in glucose with time (derivative component), and a potentiation factor, which is a function of time and may reflect the actions of nonglucose secretagogues and other factors. RESULTS: Vildagliptin significantly increased the insulin secretory rate at 7 mmol/liter glucose (secretory tone), calculated from the dose response; the difference in least squares mean (deltaLSM) was 101 +/- 51 pmol.min(-1).m(-2) (P = 0.002). The slope of the beta-cell dose response, the derivative component, and the potentiation factor were not affected. Vildagliptin also significantly decreased mean prandial glucose (deltaLSM, -1.2 +/- 0.4 mmol/liter; P = 0.01) and glucagon (deltaLSM, -10.7 +/- 4.8 ng/liter; P = 0.03) levels and increased plasma levels of intact GLP-1 (deltaLSM, +10.8 +/- 1.6 pmol/liter; P < 0.0001) and gastric inhibitory polypeptide (deltaLSM, +43.4 +/- 9.4 pmol/liter; P < 0.0001) relative to placebo. CONCLUSION: Vildagliptin is an incretin degradation inhibitor that improves beta-cell function in diabetic patients by increasing the insulin secretory tone.

Adamantane↗
PubMed2005

Comparative evaluation of simple insulin sensitivity methods based on the oral glucose tolerance test.

AIMS/HYPOTHESIS: We compared five surrogate insulin sensitivity (IS) methods against the euglycaemic-hyperinsulinaemic clamp. These methods were the homeostasis model assessment (HOMA) and four methods based on the OGTT (OGIS, MCRest, ISIcomp, SIORAL). METHODS: We compared these IS methods against the clamp (0.28 nmol.min(-1).m(-2) insulin infusion) M value in 147 women (58-61 years; BMI 19-38 kg/m2; 116 NGT, 25 IFG/IGT, six type 2 diabetic), by evaluating the correlation coefficient with M. We also tested the ability to reproduce the relationships between IS and typical IS correlates (BMI, fasting insulin, insulin to glucose OGTT area ratio and fasting, 2 h and mean glucose) by means of the "discrepancy index" D, in which (1) D=0 if the correlation between IS and the variable of interest is as with the clamp, (2) D is smaller than 0 if the correlation is overestimated, and (3) D is greater than 0 if underestimated. RESULTS: All IS methods correlated with M (r=0.57-0.83, p<0.0001); for MCRest the relationship was markedly curvilinear. All IS measures correlated with the considered variables (r=0.29-0.94, p<0.0005); however, no method had D approximately 0 for all variables. The best surrogates of M were OGIS (one D not =0) and MCRest (two D not =0); the other methods either under- or overestimated the degree of correlation (three or more D not =0), in particular with fasting insulin (HOMA: D=-57%; ISIcomp: D=-36%) and BMI (HOMA: D=-14%; ISIcomp: D=-14%; SiORAL: D=-11%). CONCLUSIONS/INTERPRETATION: All IS methods were correlated with M. OGIS and MCRest were preferable to the other methods and in particular to HOMA for reproducing relationships with the independent variables.

Blood Glucose↗
PubMed2004

Beta cell function and its relation to insulin action in humans: a critical appraisal.

The importance of both insulin resistance and beta cell dysfunction in the pathogenesis of glucose intolerance is widely recognised. Also popular is the concept that beta cell secretory function must be viewed in the context of extant insulin resistance. This For Debate moves from the premise that, whilst insulin action in vivo can be measured directly by a variety of essentially coherent techniques, measurement of beta cell function is more problematic. We therefore concisely survey the principal in vivo techniques that explore the diverse aspects of beta cell function and conclude that: (i) inter-correlation of clinical tests is only modest in non-diabetic subjects and poor in diabetic individuals; (ii) no single clinical test allows beta cell function to be assessed with accuracy and specificity comparable to those of insulin sensitivity; and (iii) short of complex experiments, mathematical modelling is necessary to interpret insulin secretory responses. Next we discuss the hyperbola paradigm used to describe the reciprocal relation of beta cell function to insulin sensitivity and suggest that: (i) insulin responses reflecting the basal beta cell tone are indeed inversely related to insulin action across degrees of glucose intolerance; (ii) modes of beta cell function that selectively reflect the dynamic response to acutely changing glucose concentrations are largely independent of insulin action; and (iii) when measured by experiment or resolved by modelling, quantitatively the most important of these dynamic secretion parameters is the glucose dose-response curve (glucose sensitivity). In fact, glucose excursions following glucose ingestion (i.e. glucose tolerance) are best explained by dynamic parameters of beta cell function.

Diabetes Mellitus↗
PubMed2004

The EGIR-RISC STUDY (The European group for the study of insulin resistance: relationship between insulin sensitivity and cardiovascular disease risk): I. Methodology and objectives.

AIMS/HYPOTHESES: Insulin resistance is thought to be a key predictor for the development of Type 2 diabetes mellitus and cardiovascular disease (CVD), a leading cause of morbidity and premature mortality in Europe. Insulin resistance is influenced by both genetic and lifestyle factors (e.g. obesity and physical inactivity). The RISC (Relationship between Insulin Sensitivity and Cardiovascular disease) Study is using the infrastructure of an extended European collaborative research group to study insulin resistance and CVD risk in 1500 healthy people aged 30 to 60 years from 20 centres in 13 countries. METHODS: Baseline measurements of glucose tolerance and insulin sensitivity are made by the oral glucose tolerance test and the euglycaemic insulin clamp, respectively; carotid artery intima-medial thickness (by ultrasound), ankle/brachial pressure index and electrocardiography will enable evaluation of subclinical CVD at baseline and at follow-up. Classic CVD risk factors, as well as socioeconomic and lifestyle factors will be recorded at baseline; samples for measurement of biochemical and genetic markers will be collected and stored for future analyses. Investigations will be repeated after 3 and 10 years to evaluate the relationship between insulin resistance and the development of atherosclerosis as measured by carotid artery intima-media thickness. Development of Type 2 diabetes, dyslipidaemia, obesity, hypertension and cardiovascular events are additional endpoints. CONCLUSIONS: This study will evaluate the importance of insulin resistance in the development of CVD and diabetes, and has implications for the development of prevention and treatment strategies.

Adult↗
PubMed2004

Allergic cross-reactivity: from gene to the clinic.

A large number of allergenic proteins have now their complete cDNA sequences determined and in some cases also the 3D structures. It turned out that most allergens could be grouped into a small number of structural protein families, regardless of their biological source. Structural similarity among proteins from diverse sources is the molecular basis of allergic cross-reactivity. The clinical relevance of immunoglobulin E (IgE) cross-reactivity seems to be influenced by a number of factors including the immune response against the allergen, exposure and the allergen. As individuals are exposed to a variable number of allergenic sources bearing homologous molecules, the exact nature of the antigenic structure inducing the primary IgE immune response cannot be easily defined. In general, the 'cross-reactivity' term should be limited to defined clinical manifestations showing reactivity to a source without previous exposure. 'Co-recognition', including by definition 'cross-reactivity', could be used to describe the large majority of the IgE reactivity where co-exposure to a number of sources bearing homologous molecules do not allow unequivocal identification of the sensitizing molecule. The analysis of reactivity clusters in diagnosis allows the interpretation of the patient's reactivity profile as a result of the sensitization process, which often begins with exposure to a single allergenic molecule.

Allergens↗
PubMed2003

Predominant role of reduced beta-cell sensitivity to glucose over insulin resistance in impaired glucose tolerance.

AIMS/HYPOTHESIS: Impaired glucose tolerance (IGT) is an insulin-resistant state and a risk factor for Type 2 diabetes. The relative roles of insulin resistance and insulin deficiency in IGT have been disputed. METHODS: In 40 IGT subjects and 63 sex-, age-, and weight-matched controls with normal glucose tolerance (NGT), we measured (i) indices of insulin sensitivity of fasting glucose production (by tracer glucose) and glucose disposal (M value on a 240 pmol x min(-1) x m(-2) insulin clamp) and (ii) indices of beta-cell function (glucose sensitivity, rate sensitivity, and potentiation) derived from model analysis (Am J Physiol 283:E1159-E1166, 2002) of the insulin secretory response (by C-peptide deconvolution) to oral glucose. RESULTS: In comparison with NGT, IGT were modestly insulin resistant (M=29+/-2 vs 35+/-2 micromol x min(-1) x kg(FFM)(-1), p=0.01); insulin sensitivity of glucose production also was reduced, in approximate proportion to M. Despite higher baseline insulin secretion rates, IGT was characterized by a 50% reduction in glucose sensitivity [53 (36) vs 102 (123) pmol x min(-1) x m(-2) x mM(-1), median (interquartile range), p=0.001] and impaired potentiation [1.6 (0.8) vs 2.0 (1.5) units, p<0.04] of insulin release, whereas rate sensitivity [1.15 (1.15) vs 1.38 (1.28) nmol x m(-2) x mM(-1)] was not significantly reduced. Glucose sensitivity made the single largest contribution (approximately 50%) to the observed variability of glucose tolerance. CONCLUSION/INTERPRETATION: In IGT the defect in glucose sensitivity of insulin release quantitatively predominates over insulin resistance in the genesis of the reduced tolerance to oral glucose.

Adult↗
PubMed2003

Skin test with a timothy grass (Phleum pratense) pollen extract vs. IgE to a timothy extract vs. IgE to rPhl p 1, rPhl p 2, nPhl p 4, rPhl p 5, rPhl p 6, rPhl p 7, rPhl p 11, and rPhl p 12: epidemiological and diagnostic data.

BACKGROUND: The diagnostic approach to grass pollen allergy is now possible by detecting specific IgE to its allergenic components. OBJECTIVE: To compare the IgE reactivity to a timothy grass pollen extract with the IgE reactivity to eight allergenic components from the same source (Phl p 1, 2, 4, 5, 6, 7, 11, 12). Both were compared with the skin test reactivity to a timothy grass extract. METHODS: A population survey was carried out by means of the skin test to identify grass-allergic subjects, and to characterize them in terms of demographic and allergological parameters. Seven hundred and forty-nine sera were available for IgE detection to a timothy extract, to the recombinant Phl p 1, 2, 5, 6, 7, 11, 12, and to native Phl p 4 and bromelain. Results were stratified by means of demographic and allergy parameters. RESULTS: Ninety-five per cent of the sera had detectable IgE to the timothy extract. Prevalence of IgE reactivity increased from 86.8% to 93.3% as the number of combined reactive molecules rose from 2 to 8. Adjusted prevalences for each allergen were: rPhl p 1 = 83%, rPhl p 2 = 55%, nPhl p 4 = 70%, rPhl p 5 = 50%, rPhl p 6 = 44%, rPhl p 7 = 7%, rPhl p11 = 43%, rPhl p 12 = 15%. Isolated reactivity to rPhl p 1 was 6%, whereas it was negligible for the remaining molecules. IgE reactivity prevalence and mean values differed when patients were stratified on the basis of their associated pollen reactivity and their skin test reactivity grade. No differences were found when age, symptom type and duration were considered. Up to eight-fold higher IgE concentrations were found when the sum of IgE to molecules was compared with IgE to the extract. Testing for the IgE reactivity to the glycan of the native Phl p 4 allergen showed a possible interference with prevalence and value estimation. Higher prevalence values were found in previously immunotherapy-treated patients. CONCLUSIONS: The use of a complete panel of grass allergenic molecules can mimic the current use of allergenic extracts, but new relevant information, such as individual pattern of reactivity, adjusted prevalence, correct specific IgE concentration, can be achieved only by means of discrete allergenic molecules.

Adolescent↗
PubMed2003

Fagales pollen sensitization in a birch-free area: a respiratory cohort survey using Fagales pollen extracts and birch recombinant allergens (rBet v 1, rBet v 2, rBet v 4).

BACKGROUND: Birch allergy is one of the most common pollinosis in areas where exposure to high levels of birch pollen is common. Little is known about birch sensitivity in areas without birch pollen exposure and reactivity to birch-related species within the Fagales order. OBJECTIVE: the aim was to evaluate Fagales reactivity within a population not exposed to birch pollen using epidemiological, diagnostic, and laboratory approaches by means of extracts and allergenic molecules. METHODS: A cohort of 5335 respiratory allergic patients was screened by means of skin testing birch, hazel, and oak pollen extracts. Patients were from a birch-free area, but exposed to other Fagales pollen species. A subset of patients was from an intensively cultivated hazel area. A sample of the Fagales allergic population was tested with other Fagales pollen extract (alder, hornbeam, beech, chestnut) and with apple and hazelnut. IgE detection was performed with birch, hazel, oak, apple, and hazelnut extracts, and with Bet v 1, Bet v 2, Bet v 4, and bromelain. IgE immunoblots were performed using birch and hazel extracts. Epidemiological, clinical, and laboratory data were analysed by stratifying the allergic population. RESULTS: Twenty-five percent of the pollen allergic cohort was skin test positive to at least one of the three Fagales species. Combined reactivity to the three species was recorded in 80% of this cohort. Isolated hazel pollen reactivity was recorded in 13.5% of the Fagales allergic patients. Sixty-six percent of these subjects were from the intensively cultivated hazel area. Reactivity to apple and hazelnut was detected by skin test (40%) and IgE reactivity (60%), but only 19% of the positive patients reported symptoms related to at least one of the two foods. Reactivity to Bet v 1 was recorded in 84% of the birch/hazel/oak co-reactivity group, and in 28% of the subjects with the same co-reactivity, but associating a multiple pollen sensitization. IgE to Bet v 2 (50%) and Bet v 4 (23%) panallergens were recorded positive in the latter subset. Bet v 1 prevalence ranged between 48% and 21% among subgroups of patients coming from different areas. Furthermore, an IgE reactivity to hazel-restricted allergenic components was detected among subjects coming from the same area and having a hazel isolated reactivity. CONCLUSION: Fagales allergy can be found in birch-free areas caused by the exposure to other Fagales species. Birch allergens can be useful for mimicking the allergenic extract, but are also the exclusive tools for a fine diagnostic and epidemiological approach to Fagales pollen allergy. Allergenic molecules from the hazel family will increase the panel of available reagents for the molecule-based approach to allergy diagnosis and therapy.

Adult↗
PubMed2003

Sensitization to fungi: epidemiology, comparative skin tests, and IgE reactivity of fungal extracts.

BACKGROUND: Several fungal species are known to cause severe respiratory and cutaneous allergic diseases. Extracts from several allergenic fungi are used for in vivo and in vitro tests, as standard preparations are still not available. OBJECTIVE: The aims are to define the pattern of in vivo and in vitro IgE reactivity to fungal species in an allergic population with respiratory symptoms; to determine the influence of different extract preparations on diagnostic results; and to evaluate whether there exists a relationship between the diagnostic pattern of reactivity and the pattern of specific IgE reactivity in immunoblots. METHODS: Skin prick tests were applied to a cohort of 4962 respiratory subjects, aged 3-80 years. Fungal extracts from Alternaria, Aspergillus, Candida, Cladosporium, Penicillium, Saccharomyces, and Trichophyton were used, along with extracts from pollens, mites, and animal dander. Demographical and diagnostic data were recorded. IgE detection was carried out with the same allergenic extracts plus Malassezia. Comparative skin tests and IgE detection were carried out using extracts from three commercial suppliers. IgE immunoblots were carried out with the same panel of commercial fungal extracts and were compared with in-house extracts. Data analysis was carried out by grouping the population on the basis of their reactivity to a single, to two or to more than two, mould species. RESULTS: Nineteen percent of the allergic population reacted to at least one fungal extract by means of the skin test. Alternaria and Candida accounted for the largest number of positive tests, and along with Trichophyton they were the main sensitizers in the subset of patients with an isolated sensitization. The prevalence of skin test reactivity increased for these three fungi in the subsets with two associated reactivities and, furthermore, in the subset showing reactivity to more than two mould species. In the latter group, a steady increase of the skin test reactivity was recorded for all the other fungal sources, suggesting a clustered reactivity. Comparative skin and IgE testing with different groups of subjects with a simple pattern of skin reactivity resulted in sensitivity differences between in vivo and in vitro tests, whereas discrepant results were recorded in the subsets of patients with multiple fungi sensitization. Although hampered by the limited reliability of fungal extracts, IgE immunoblots revealed differing patterns of reactivity when sera from the three subsets were used. This suggests a link between the diagnostic reactivity pattern and the IgE sensitization to extracts' components. Age and gender distribution differed among the Alternaria-, Candida-, and Trichophyton-sensitized subjects, but not in the subset with more than two fungi sensitizations. CONCLUSIONS: The preliminary assessment of a new classification of the mould-sensitized population has been reached. The limiting quality of fungal extracts requires future studies using an allergenic molecule-based approach. The diagnostic process and the definition of the reactivity pattern would thus be easy, and it could lead to a novel specific immunotherapy approach.

Adolescent↗