Biomedical subjects

Athina Papadopoulou

Publications and source records attributed to Athina Papadopoulou.

8 recordsLinked to original sources

PubMed2006

Isothermal titration calorimetry study of epicatechin binding to serum albumin.

The interaction of epicatechin with bovine serum albumin (BSA) was studied by isothermal titration calorimetry. The binding constant (K) and associated thermodynamic binding parameters (n, DeltaH) were determined for the interaction at three solution concentrations of BSA using a binding model assuming independent binding sites. These data show weak non-covalent binding of epicatechin to BSA. The interaction energetics varied with BSA concentration in the calorimeter cell, suggesting that the binding of epicatechin induced BSA aggregation. The free energy (DeltaG) remained constant within a range of 2 kJ mol(-1) and negative entropy was observed, indicating an enthalpy driven exothermic interaction. It is concluded that the non-covalent epicatechin-BSA complex is formed by hydrogen bonding.

Algorithms↗

PubMed2006

Bronchial hyperresponsiveness, atopy, and bronchoalveolar lavage eosinophils in persistent middle lobe syndrome.

Most cases of middle lobe syndrome (MLS) in children are considered to be due to asthma and may recover spontaneously; however, in persistent MLS, repeated episodes of infection often institute a vicious cycle that may lead to persistent symptoms and bronchial hyperresponsiveness (BHR). The present study was undertaken to investigate whether asthma, as an underlying diagnosis, is predictive of a favorable outcome of children with persistent MLS. We evaluated 53 children with MLS who underwent an aggressive management protocol that included fiberoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL). These patients were compared to two other groups: one consisting of children with current asthma but no evidence of MLS (N = 40) and another of non-asthmatic controls (N = 42), matched for age and sex. Prevalence of sensitization (>or=1 aeroallergen) did not differ between patients with MLS and "non-asthmatics" but was significantly lower than that of "current asthmatics." A positive response to methacholine bronchial challenge was observed with increased frequency among children with MLS when compared to "current asthmatic" and non-asthmatic children. Multivariate logistic regression analysis revealed a positive correlation between an increased number of eosinophils in the BAL fluid (BALF) and a favorable outcome, whereas no correlation was detected between sensitization or BHR and BAL cellular components. In conclusion, children with MLS have an increased prevalence of BHR, even when compared to asthmatics, but exhibit prevalence of atopy similar to that of non-asthmatics. An increased eosinophilic BALF count is predictive of symptomatic but not radiographic improvement of MLS patients after aggressive anti-asthma management.

Asthma↗

PubMed2005

Serum eosinophil cationic protein and CD23 in acute RSV bronchiolitis.

BACKGROUND: Elevated concentrations of eosinophil cationic protein (ECP) have been found in acute viral wheezing during infancy. Furthermore, RSV infection has been suggested to stimulate type-2 cytokine responses. The aim of this study was to test whether serum ECP and soluble CD23 levels, which are markers of eosinophil and IgE responses, respectively, are elevated in infants hospitalized for acute respiratory syncytial virus (RSV) bronchiolitis. MATERIAL/METHODS: Fifty-five infants aged 1-12 months (median: 4.2 months) consecutively hospitalized for acute bronchiolitis were divided into two groups: RSV-positive (n=26) and RSV-negative patients (n=29). Serum ECP (s-ECP), soluble CD23 (sCD23), and total IgE were measured in all patients and in 23 asymptomatic infants (controls). RESULTS: Lower s-ECP levels were detected in the RSV-positive group (5.4+/-4.3 ng/dl) compared with controls (9.38+/-5.95 ng/dl, p=0.02), but they did not differ significantly from the values of RSV-negative patients (7.8+/-5.7 ng/dl). There was a trend to higher s-ECP values in patients with a positive family history of atopy and/or a history of atopic dermatitis in the RSV-positive group (p=0.06). No differences in sCD23 and total IgE levels among the groups were detected. No correlation between total IgE and sCD23 values was observed. CONCLUSIONS: There is no evidence from our data to suggest that either RSV-positive or RSV-negative acute bronchiolitis is associated with significant eosinophil-mediated degranulation. There is no evidence from the sCD23 data to support the hypothesis that IgE antibody responses are prominent during the acute illness.

Bronchiolitis, Viral↗

PubMed2005

Interaction of flavonoids with bovine serum albumin: a fluorescence quenching study.

The interaction between four flavonoids (catechin, epicatechin, rutin, and quercetin) and bovine serum albumin (BSA) was investigated using tryptophan fluorescence quenching. Quenching constants were determined using the Stern-Volmer equation to provide a measure of the binding affinity between the flavonoids and BSA. The binding affinity was strongest for quercetin and ranked in the order quercetin > rutin > epicatechin = catechin. The pH in the range of 5-7.4 does not affect significantly (p < 0.05) the association of rutin, epicatechin, and catechin with BSA, but quercetin exhibited a stronger affinity at pH 7.4 than at lower pH (p < 0.05). Quercetin has a total quenching effect on BSA tryptophan fluorescence at a molar ratio of 10:1 and rutin at approximately 25:1. However, epicatechin and catechin did not fully quench tryptophan fluorescence over the concentration range studied. Furthermore, the data suggested that the association between flavonoids and BSA did not change molecular conformation of BSA and that hydrogen bonding, ionic, and hydrophobic interaction are equally important driving forces for protein-flavonoid association.

Drug Interactions↗

PubMed2005

Bronchial hyper-responsiveness in selective IgA deficiency.

Secretory IgA in mucosal secretions has a broad protective function. The insufficient protection provided by the respiratory mucosa in children with selective IgA deficiency (sIgAD) might facilitate the development of bronchial hyper-responsiveness (BHR) and consequently asthma symptoms. This study was conducted to clarify the prevalence of BHR in sIgAD children and the relationship with atopic status. A cohort of 20 children (group A) aged 6.4-20.1 yr (median: 12.6) with sIgAD (serum IgA <6 mg/dl) were evaluated for BHR using inhaled hypertonic saline test as well as for atopy by skin prick testing (SPT) to eight common aero-allergens. Seventy other children with normal levels of serum IgA, but sensitized to aero-allergens (group B) and 102 with normal IgA and negative SPTs (group C) were also evaluated. Baseline spirometry demonstrated that forced vital capacity (FVC) values in group A were significantly lower than in C. Forced expiratory volume in 1 s values were similar in all groups, but impairment of the forced expiratory flow over the middle half of the FVC was detected in group B. The prevalence of BHR was similar among group A (30.0%) and group B (35.7%) (p = 0.79) but they differed from group C (5.9%) (p = 0.005). An association between BHR and reported current (p = 0.001) but not lifetime asthma symptoms among group A was also observed. There was no association between atopy and BHR in group A but only to mites' sensitization (p = 0.03). In conclusion, these results indicate that sIgAD constitutes a risk factor for development of BHR but it appears to be related to sensitization to mites.

Adolescent↗

PubMed2005

The role of timely intervention in middle lobe syndrome in children.

STUDY OBJECTIVES: Middle lobe syndrome (MLS) in children is characterized by a spectrum of clinical and radiographic presentations, from persistent or recurrent atelectasis to pneumonitis and bronchiectasis of the right middle lobe (RML) and/or lingula. This study was undertaken to evaluate the effect of early intervention, including fiberoptic bronchoscopy (FOB), in the development of bronchiectasis in MLS. DESIGN: Children with atelectasis of the RML and/or lingula persisting for > 1 month or recurring two or more times despite conventional treatment underwent high-resolution CT (HRCT) scanning and FOB. Appropriate treatment and follow-up were provided, and the effect of the duration of symptoms on clinical outcome and the development of bronchiectasis was investigated. The patient cohort was retrospectively reviewed. PATIENTS: We evaluated 55 children with MLS. The median age at diagnosis, duration of symptoms, and duration of clinical deterioration before diagnosis were 5.5 years (range, 3 months to 12 years), 14.5 months (range, 3 to 48 months), and 8 months (range, 3 to 36 months), respectively. MEASUREMENTS AND RESULTS: FOB revealed marked obstruction in two children (ie, a foreign body and an endobronchial tumor) and positive findings for a culture of BAL fluid in 49.1% of patients. The remaining 53 patients were followed up for a median duration of 24 months (range, 5 to 96 months). The clinical outcome was "cure" in 60.4% of patients, "improvement" in 32.1% of patients, and "no change" in the remaining patients. Bronchiectasis was documented prior to FOB by HRCT scan in 15 patients (27.3%). The duration of the deterioration of symptoms prior to presentation positively correlated with the development of bronchiectasis (p = 0.03) and an unfavorable clinical outcome (ie, improvement or no change) [p = 0.02]; a positive correlation was also found between the duration of symptoms and the development of bronchiectasis (p = 0.04). CONCLUSIONS: Timely medical intervention in patients with MLS that includes FOB with BAL prevents bronchiectasis that may be responsible for an ultimately unfavorable outcome.

Bronchiectasis↗

PubMed2003

Probing protein-tannin interactions by isothermal titration microcalorimetry.

Isothermal titration microcalorimetry (ITC) has been applied to investigate protein-tannin interactions. Two hydrolyzable tannins were studied, namely myrabolan and tara tannins, for their interaction with bovine serum albumin (BSA), a model globular protein, and gelatin, a model proline-rich random coil protein. Calorimetry data indicate that protein-tannin interaction mechanisms are dependent upon the nature of the protein involved. Tannins apparently interact nonspecifically with the globular BSA, leading to binding saturation at estimated tannin/BSA molar ratios of 48:1 for tara- and 178:1 for myrabolan tannins. Tannins bind to the random coil protein gelatin by a two-stage mechanism. The energetics of the first stage show evidence for cooperative binding of tannins to the protein, while the second stage indicates gradual saturation of binding sites as observed for interaction with BSA. The structure and flexibility of the tannins themselves alters the stoichiometry of the interaction, but does not appear to have any significant affect on the overall binding mechanism observed. This study demonstrates the potential of ITC for providing an insight into the nature of protein-tannin interactions.

Calorimetry↗

PubMed2003

Recent advances in the application of capillary electrophoresis for food analysis.

This article reviews recent developments in the application of capillary electrophoresis (CE) for the analysis of foods and food components. CE has been applied to a number of important areas of food analysis and is fast becoming an established technique within food analytical and research laboratories. Papers are reviewed that were published during the two years to date following the previous review (Electrophoresis 2001, 22, 4197-4206).

Amino Acids↗