Search

In our previous study (Mustan et al. 2021) we showed that foams formed from two oil-soluble nonionic surfactants (Span 60 and Brij 72) can remain stable for more than 10 days at room temperature at high sugar concentration. The major aim of the current study is to reveal the interrelation between the surfactant structure and foam stability by investigating 6 polyoxyethelene alkyl ethers and 12 fatty acid esters with a wide variety of hydrophobic chain lengths (C12; C16; C18 and C18:1) and hydrophilic head-groups (sorbitol, glycerol, sucrose). Foams stable for more than 100 days at room temperature are obtained when sucrose palmitate or stearate (P1670 or S1670) are used as surfactants. This exceptional foam stability is related to the gelation of the aqueous phase and to the formation of solid adsorption layer with zero surface tension upon compression, thus preventing water drainage and decelerating the bubble Ostwald ripening. The foam stability decreases with (i) increasing the number of EO groups in polyoxyethylene alkyl ethers and in fatty acid sorbitan esters; (ii) decreasing the number of C-atoms in the surfactant tail for all studied surfactants; (iii) addition of double bond in the surfactant tail. The lower foam stability in all three cases is related to the worse packing of the surfactant molecules within the adsorption layer, leading to faster Ostwald ripening and subsequent bubble coalescence. The diesters present as admixture in the fatty acid esters play an important role in the foam stabilization by further compacting the adsorption layers and lowering the rate of Ostwald ripening. These conclusions can be used as a predictive tool for surfactant selection in the development of food or pharmaceutical foam concentrates that can be diluted before final use., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Inherited epidermolysis bullosa (EB) is a clinically and genetically heterogeneous group of rare diseases characterized by skin and mucous membrane fragility. EB primarily involves the skin and, in specific subtypes, the mucous membrane, resulting in complications which can strongly affect nutritional status (e.g. gastrointestinal complications, hand deformities, pain). The aims of nutritional support mainly include improving nutritional status, alleviating the stress of oral feeding and minimizing nutritional deficiencies, thus consequently improving growth, pubertal development, bowel function, immune status and wound healing. The aim of this review is to discuss knowledge of different aspects of the disease related to nutrition and growth., (Copyright © 2019 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.)

Background: Topical steroids are effective in eosinophilic esophagitis (EoE), but patients often show different tendencies to relapse. We assessed whether gene expression is associated with a sort of steroid dependency in EoE children., Methods: Biopsy samples were prospectively collected on EoE children responding to topical steroids. Patients treated with viscous budesonide for 24 weeks were subsequently classified as early (6 months) or late (>6 months) relapsing. RNA was isolated from esophageal biopsies at the time of the relapse and analyzed by NGS for transcriptome profiling., Results: Of 40 patients, 22 patients were considered for mRNA expression profile. Thirteen were included in the early-relapse group, and 9 were in the late-relapse. No significant difference was observed in the two groups for clinical, endoscopic or histological features. Using the mRNA expression profile we performed supervised clustering using the 10 top differentially expressed genes between early and late relapsing patients. The heatmap and PCA show a proper segregation among patients. SERPINB12 is the only gene attaining a significant differential expression between the two groups (FDR < 0.05)., Conclusions: Different tendencies to relapse in EoE children responding to topical steroids might be related to altered mRNA expressions. SERPINB12 presented a significantly higher expression in the late relapse group and it deserves further investigations., (Copyright © 2019. Published by Elsevier Ltd.)

Background: Gastro-oesophageal reflux is very common in the paediatric age group. There is no single and reliable test to distinguish between physiologic and pathological gastro-oesophageal reflux, and this lack of clear distinction between disease and normal can have a negative impact on the management of children., Aims: To evaluate the usefulness of 24-h oesophageal pH-impedance study in infants and children with suspected gastro-oesophageal reflux disease., Methods: Patients were classified by age groups (A-C) and reflux-related symptoms (typical and atypical). All underwent pH-impedance study. If the latter suggested an abnormal reflux, patients received therapy in accordance with NASPGHAN/ESPGHAN recommendations, while those with normal study had an additional diagnostic work-up. The efficacy of therapy was evaluated with a specific standardized questionnaire for different ages., Results: The study was abnormal in 203/428 patients (47%) while normal in 225/428 (53%). Of those with abnormal study, 109 exhibited typical symptoms (54%), and 94 atypical (46%). The great majority of the patients with abnormal study were responsive to medical anti-reflux therapy., Conclusions: We confirm the utility of prolonged oesophageal pH-impedance study in detecting gastro-oesophageal reflux disease in children and in guiding therapy. Performing oesophageal pH-impedance monitoring in children with suspected gastro-oesophageal reflux disease is helpful to establish the diagnosis and avoid unnecessary therapy., (Copyright © 2018 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.)

Human whole saliva (HWS) is a physiological secretion that performs a number of essential functions including protection of oral health, lubrication of mouth tissues and food pre-digestion. The complexity of the saliva proteome reflects the unique physiochemical functionality of this biofluid. In addition, saliva influences the transduction of aroma, taste and tactile (mouthfeel) perceptions through the interaction with food and beverages. This work, which is presented as two distinct contributions, reports on the extensive interfacial properties characterization (air-liquid) of saliva either alone or after exposure to tea polyphenols. This first part discusses the complex nature of the salivary film in terms of kinetic and viscoelastic (dilational surface rheology) properties. The formation of the surface film is analyzed with time and explained in terms of the progressively irreversible adsorption of protein fractions of larger molecular weight. The viscoelastic response to appropriate frequency modulation is modelled using a general mixed kinetic model, which satisfactorily reproduces the experimental data in better agreement than the traditional Lucassen diffusive model., (Copyright © 2013 Elsevier B.V. All rights reserved.)

In the second part of this communication we screen a few tea polyphenols for their ability to interact with pre-adsorbed salivary proteins at the air-liquid interface. Using interfacial dilational rheology characterisation, we measure the variation in surface elasticity of a pre-adsorbed salivary film after exposure to tea polyphenols solutions in order to probe the degree of mutual interaction. We observe that this interaction with salivary proteins varies according to the chemical structure and degree of polyphenols complexity (number of phenols rings). The evolution of the salivary film after exposure to polyphenol solutions is characterised through surface dilational response to appropriate frequency modulation and the results are analysed using a general mixed kinetic model, which reproduces correctly the experimental data except for the galloylated theaflavins., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: The melanocortin receptor-5 (MC5R) is present in human sebaceous glands, where it is expressed in differentiated sebocytes only. The targeted disruption of MC5R in mice resulted in reduced sebaceous lipid production and a severe defect in water repulsion., Objective: To investigate the physiological function of MC5R in human sebaceous glands., Methods: A novel MC1R and MC5R antagonist (JNJ-10229570) was used to treat primary human sebaceous cells or human skins grafted onto severe combined immunodeficient (SCID) mice. Transcription profiling, lipid analyses, and histological and immunohistochemical staining were used to analyze the effect of MC5R inhibition on sebaceous gland differentiation and sebum production., Results: JNJ-10229570 dose dependently inhibited the production of sebaceous lipids in cultured primary human sebocytes. Topical treatment with JNJ-10229570 of human skins transplanted onto SCID mice resulted in a marked decrease in sebum-specific lipid production, sebaceous gland's size and the expression of the sebaceous differentiation marker epithelial-membrane antigen (EMA). Treatment with flutamide, a known inhibitor of sebum production, gave similar results, validating the human skin/SCID mouse experimental system for sebaceous secretion studies., Conclusion: Our data suggest that antagonists of MC1R and MC5R could be effective sebum suppressive agents and might have a potential for the treatment of acne and other sebaceous gland pathologies., (Copyright © 2011 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

Background: Solar lentigines (SLs) are macular hyperpigmented lesions associated with sun exposure and age. Histopathologically, SLs are defined by a hyperpigmented basal layer and elongated rete ridges. The molecular mechanisms involved in the formation and the development of SLs are not completely understood. Our earlier data show that keratinocyte growth factor (KGF) induces hyperpigmentary lesions with histological resemblance to SLs., Objective: To investigate the association of KGF/KGF receptor (KGFR) and other pigmentary genes with the progression of SL development. To better understand the possible role of KGF in the pathology of SLs., Methods: Archived human skin biopsies (24 SLs and 14 healthy skins) were studied using immunohistochemistry for KGF/KGFR, proliferation marker Ki67, stem cell marker keratin-15 (K15), tyrosinase (TYR), stem cell factor (SCF), and protease-activated receptor-2 (PAR-2)., Results: An increase in TYR-positive cells and expression was found throughout SL progression, as compared to normal skin. The levels of KGF, KGFR, SCF, Ki67 and PAR-2 varied during SL progression. Ki67, K15 and KGF/KGFR were significantly upregulated at early-mid SL stages. The latest-stage SLs expressed the lowest levels of KGF, KGFR, SCF, Ki67 and PAR-2., Conclusions: The upregulation of KGF/KGFR might induce the formation of rete ridges and hyperpigmentation. The reduced levels of all examined proteins (except TYR and K15) suggest a possible inactive status (dormancy or quiescence) of advanced lesions., (Copyright 2010 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

In this review various aspects concerning the application of capillary (zone) electrophoresis for peptide analysis will be critically examined. First, the basic instrumental requirements of CE apparatus and the strategies employed to enhance sensitivity in the analysis of underivatized sample are described. Multidimensional separative techniques of complex peptide mixtures that use CE as final step and the coupling of CE with mass spectrometry are subsequently discussed. A theoretical section describes the relationships existing between peptide mobility and the pH of the separation buffer. These relationships evidence that proton dissociation constants and Stokes radius at different protonation stages can be calculated by measuring the electrophoretic mobility at different pH values. Investigation of peptide mobility dependence on pH allows us to establish the optimum conditions, in terms of resolution, for peptide separation. Subsequently, a critical discussion about semiempirical models predicting peptide mobility as a function of chemico-physical peptide properties is presented. A section is devoted to the description of principles of peptide affinity capillary electrophoresis, underlining the similarity with peptide-proton interaction. CE separations performed in aquo-organic solvents are also critically discussed, showing the good performance obtained by using water-2,2,2-trifluoroethanol solutions. Finally, selected CE applications for the determination of peptide chemico-physical properties and conventional analysis, like peptide mapping, are reported.

The use of 2,2,2-trifluoroethanol-water mixtures for peptide separations by capillary zone electrophoresis (CZE) displays some advantages over aqueous solutions. First, the increase in viscosity reduces and stabilizes the running current and facilitates heat dispersion, with a consequent improvement in the number of theoretical plates. Second, the decrease in the dielectric constant leads to a modification of the dissociation constants of the ionizable groups. The consequence is a change in selectivity that, for several favourable peptide pairs, provides an increase in resolution. Third, the interaction trifluoroethanol with the peptide modifies the Stokes radius in a manner strongly dependent on the peptide sequence. This can also be utilized for an increase in CZE performance. Fourth, the structural properties of 2,2,2-trifluoroethanol are particularly useful for an improvement in the separation of large apolar peptides. Finally, the use of trifluoroethanol strongly stabilizes the capillary coating.

The determination of the pKa values of some selected peptides of similar size was performed by microtitration, which makes possible an accurate determination of the peptide charge as a function of the solution pH. Capillary zone electrophoresis separation of these peptides on modified capillaries at acidic pH showed that the electrophoretic mobility correlates with the peptide charge. This observation suggests that when an appropriate charge value is used, the basic electrophoretic equation is respected and, at least at a peptide charge value less than 1, the utilization of alternative semi-empirical predictions is not necessary. As a general rule, a peptide separation at acidic pH values is to be preferred to that at basic pH values. In fact, at basic pH a separation in the absence of both electroosmotic flow and of spurious interactions between the peptides and the inner wall of the capillary is difficult, owing to the instability of capillary modification. Further, from the differences in the peptide charge, a prediction of the best resolution as a function of the pH could be obtained; in fact, the resolution, for peptides of similar size and in the absence of electroosmotic flow, is connected to a simple equation, where the principal term depends on the effective charge of the peptides, which is a function of the pH of the solution and the pKa values of the peptides. The predictions of resolution at acidic pH agreed well with the experimental results; the spatial resolution measured in the separation of met- and leu-enkephalin was virtually coincident with the predicted resolution; in the case of a mixture of four model tetrapeptides of sequence GGNA, GGQA, GGDA and GGEA some anomalous results with respect to the predicted resolutions were observed. Nevertheless, an acceptable prediction can also be made in this case.

The tryptic map of horse myoglobin was analysed through capillary electrophoresis using capillaries modified by a monolayer of acrylamide. The results were reproducible and the map was obtained in less than 30 min from ca. 8 pmol of tryptic digest. The peptide identification was performed using peptides previously identified by high-performance liquid chromatography. The peak areas measured using the two techniques are closely related, and the comparison of elution and migration times shows that the two techniques provide different maps. Furthermore, using the semiempirical relationship suggested by Grossman et al. [Anal. Biochem., 179 (1989) 28], which links the electrophoretic mobility to the charge of the peptide and its number of amino acids, a good agreement between predicted and experimental mobilities was observed.

The globins from all fast haemoglobin (Hb) components obtainable by Bio-Rex 70 cation-exchange chromatography were examined by isoelectrofocusing on polyacrylamide gel rods with 8.0 mol/l urea. From this analysis HbA1a1 and HbA1a2 seem to be very heterogeneous components. HbA1b is separable into two components, one of which is varied in both the beta chains. Between HbA1b2 and the well-known HbA1c components two chromatographic peaks are separated, one with a noticeable percentage of glucosylated beta chain and one that probably contains HbF. HbA1c has both beta chains glucosylated, while HbA1x seems to be a beta monoglucosylated Hb form. Finally, the early part of the HbAo peak has a large amount of glucosylation on both alpha and beta chains.

The use of reversed-phase high-performance liquid chromatography (RP-HPLC) for the determination of protein sequences is reported. Topics considered include the peptide separation of endoprotease digestion mixtures, the application of HPLC peptide mapping as an efficient system to check the accuracy of an assumed protein sequence, obtained indirectly by DNA sequencing and the use of HPLC for amino acid analysis in the Edman sequence strategy. The use of RP-HPLC for an unconventional sequence strategy is demonstrated; HPLC exopeptidase mapping appears to be particularly useful as a future technique for small terminal sequence analysis. Finally, the coupling of HPLC with fast atom bombardment mass spectrometry is discussed.

The use of Bio-Rex 70 cation-exchange resin for chromatography of normal and diabetic hemoglobin provides a reproducible pattern of the "fast components". Particular attention to the choice of sample preparation, pH of elution, and the increase of ionic strength by sodium chloride linear gradients results in the separation of Hb-A1b into two components and in the isolation of a new component eluting between Hb-A1c and Hb-A0. Experiments with [3H]glucose and the colorimetric test (thiobarbituric acid) normally used to determine the extent of non-enzymatic glycosylation, as well as an increase of this component in diabetic samples compared with normoglycemic ones and a significant linear correlation with Hb-A1c, indicate that this component should be a part of the hemoglobins glucosylated on the epsilon-NH2 group of the lysines of both chains and/or the hemoglobin glucosylated on the alpha-NH2 of the valine of the alpha-chain. We propose to call this component Hb-A1x, pending confirmation of its identity. Normally Hb-A1x accounts for about 3% of Hb-A, but up to 5-7% of glucosylated hemoglobins should be confined to the early part of Hb-A0. In diabetics, the percentage of Hb-A1x rises to 4-5% and that of the other glucosylated hemoglobins increases to 12-16%.