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Papers by Christian Sanchez

Gastrointestinal Endoscopy, 2017

Background: Open access endoscopy can provide a timely and efficient service. Since 2011 we have ... more Background: Open access endoscopy can provide a timely and efficient service. Since 2011 we have provided an open access bidirectional endoscopy (BDE) service for iron deficiency anaemia (IDA) in our local catchment area. Inclusion criteria are age 50-79 years (and postmenopausal if female), ferritin 20 ng/ml, haemoglobin 13 g/dl for men and 11 g/dl for women. Exclusion criteria are too frail for full bowel prep or colonoscopy, IDA previously investigated, known active inflammatory bowel disease, known coeliac disease or positive tissue transglutaminase antibody result. Haemoglobin and ferritin results are checked before accepting the referral and BDE is performed within 2 weeks. Aim: To analyse the uptake and effectiveness of our local open access BDE pathway for IDA Methods: All patients having same day BDE for the indication of anaemia were retrospectively identified using the endoscopy database over a 3 month period. Prior haemoglobin and ferritin were documented and clinic follow ups identified via an electronic patient record database. Results: 51 patients were identified as having BDE for anaemia over the study period. 27 had BDE via the open access pathway, age range 55-79, haemoglobin range 67-122 g/dl for men, haemoglobin range 64-110 g/dl for women and ferritin range was 3-22 ng/ml. All had distal duodenal biopsies performed. Only three of these 27 patients were subsequently seen in the local gastroenterology clinics over a one year follow up period; one had coeliac disease, one had ulcerative colitis and one had cancer. One patient had a repeat gastroscopy to check for ulcer healing. There were 24 patients that had BDE via secondary care referral and five were >80 years and three were <50 years of age. Of the 16 secondary care referrals aged 50-79 years, ten did not fulfil the haemoglobin and/or ferritin criteria of the open access BDE pathway. Only two of the remaining six patients did not have an obvious reason why they had not been referred via the open access BDE pathway for IDA. Discussion: Our mature open access BDE service for IDA is highly utilised by primary care practitioners with over 90% of patients fulfilling the inclusion criteria (and without complicating factors) being referred via this pathway. Only 3 of the 27 patients having open access BDE for IDA were subsequently seen in the local gastroenterology clinics over a one year follow up period. The results demonstrate a timely and efficient open access BDE service for IDA.

Gastrointestinal Endoscopy, 2013

2008 5th International Conference on Electrical Engineering, Computing Science and Automatic Control, 2008

ABSTRACT Conceptualization of the Web as a universal medium for data, information, and knowledge ... more ABSTRACT Conceptualization of the Web as a universal medium for data, information, and knowledge exchange, has drawn attention both of the software engineering and AI communities to semantic service oriented architecture (SOA). One of the challenges of SOA is to deal with service matching which is uncertain and ambiguous. A service requester must be prepared to cope with situations where no required services are found or, on the other hand, multiple matching services are found. The paper proposes a formal model of service discovery with incomplete information defined using set theory, description logic and fuzzy logic. The algorithm for dynamic service composition based on missing information matching implementing the proposed model is described. The approach is illustrated by a case study, in which the algorithm is compared with the previously reported ones and its advantages are discussed.

Journal of Colloid and Interface Science, May 1, 2010

The influence of hydrolyzed soy proteins on calcium carbonate stabilization was studied in citric... more The influence of hydrolyzed soy proteins on calcium carbonate stabilization was studied in citric acid solution. Calcium-soy proteins interactions were characterized using a calcium ion selective electrode, turbidity, and Isothermal Titration Calorimetry. Once the meta-stable phase was reached or just after soy protein addition, spray-drying was performed and SEM, XRD, and XPS analysis were carried out on spray-dried powders. In citric acid solution calcite crystals were eroded giving rise to smaller amorphous particles. In the presence of soy proteins, complexation exothermic in nature occurred with the mineral phase, which prevented CaCO(3) from recrystallisation and kept the system in an amorphous state. SEM performed on spray-dried powder showed that soy proteins were swollen in presence of mineral phase and resulted in a decrease of calcium concentration at the extreme surface of the studied powders as demonstrated by XPS.

J Agr Food Chem, 2006

The specific effects of heat treatment and/or addition of low/high-methylated pectin (LMP/HMP) on... more The specific effects of heat treatment and/or addition of low/high-methylated pectin (LMP/HMP) on the allergenicity of -lactoglobulin ( -Lg) and its hydrolysis products were investigated through a twostep in vitro digestion approach. -Lg was first hydrolyzed by pepsin and then by a trypsin/chymotrypsin (T/C) mixture done in a dialysis bag with a molecular weight cutoff of 1000. The protein digestion was followed by SDS-PAGE electrophoresis performed on each digestion product, and their in vitro allergenicity was analyzed by immunoblotting. Such procedure was applied on -Lg samples mixed with the two kinds of pectin before or after heating (80°C, 25 min) to determine the respective impact of heat treatment and pectin addition. Heat denaturation improved significantly the susceptibility of -Lg against the pepsin and the T/C. This effect, which was coupled to a reduction in immunoreactivity of the digested -Lg, appeared to be distinctively modulated by LMP and HMP. Through nonspecific interaction with the -Lg, pectin could reduce the accessibility of cleavage sites and/or epitope sequences. This mechanism of action is discussed in relation to the intra-and intermolecular interactions between -Lg and pectin initiated under the experimental conditions.

Journal of Muscle Foods, Jul 1, 2000

Beef sausages extended with common bean flour were manufactured using 5 levels of fat and added w... more Beef sausages extended with common bean flour were manufactured using 5 levels of fat and added water (AW) (25% fat /5% AW; 20% fat/10% AW; 15% fat /15% AW; 10% fat/20% AW and 5% fat 25% AW). Decreasing in fat levels with a simultaneous increase in the amount of added water did not affect (P>0.05) pH and ash content, but decreased cooking yields and increased expressible moisture. The lowest L* (lightness) values (p < 0.05) was recorded for the 25% fat/5% AW formulation. High-fat, low-added water batter required more extrusion shear stress than low-fat, high-added water batter. Beef sausage textural characteristics were reduced by replacing added water by fat.

Langmuir, 2005

pH-Induced structural changes during complex coacervation between beta-lactoglobulin (BLG) and Ac... more pH-Induced structural changes during complex coacervation between beta-lactoglobulin (BLG) and Acacia gum (AG) in aqueous solutions were determined by coupling slow in situ acidification of BLG/AG mixed dispersions and different experimental methods. The combined signal evolution of dynamic light scattering at 90 degrees scattering angle (I(90)), electrophoretic mobility, turbidimetry (tau), circular dichroism, and phase contrast microscopy allowed the distinction of critical structural transitions and the definition of their corresponding pH. The formation of soluble BLG/AG complexes was initiated at pH(sc) (4.90), since I(90) and tau significantly increased from the baseline. In parallel or just following complexation, a conformational change of BLG was detected at pH(pct) (4.8). An increase in positive charge density of BLG induced complex aggregation at pH(ca) (4.7). More efficient charge neutralization of aggregated complexes, especially through the lowering of the number of AG negative charges, promoted initiation of phase separation at pH(psi) (4.4). Mixed dispersions became unstable and phase separation occurred at pH(ps) (4.2). The phase separation of mixed dispersions was suggested by the maximum value of scattered light, by an important acceleration of the dispersion turbidity, by a strong increase of hydrodynamic radii, and by the first appearance of light fluctuations as observed by phase contrast microscopy. At the microscopic level, the first coacervates were observed at pH(coa) (4.0), near the pH of the maximum of turbidity. It was also noticed that, from the onset of interactions between biopolymers, the pH decrease led to (i) a gradual homogenization of particle size in the mixed dispersion as suggested by the decrease of dispersion polydispersity and (ii) conformational transitions of the protein (a loss of alpha-helix structure at pH(pct) and a gain in protein secondary structure near pH(coa), probably involving beta-sheet components).

Critical Reviews in Food Science and Nutrition, Jun 3, 2010

Food proteins and polysaccharides are the two key structural entities in food materials. Generall... more Food proteins and polysaccharides are the two key structural entities in food materials. Generally, interactions between proteins and polysaccharides in aqueous media can lead to one- or two-phase systems, the latter being generally observed. In some cases of protein-polysaccharide net attraction, mainly mediated through electrostatic interactions, complex coacervation or associative phase separation occurs, giving rise to the formation of protein-polysaccharide complexes. Physicochemical factors such as pH, ionic strength, ratio of protein to polysaccharide, polysaccharide and protein charge, and molecular weight affect the formation and stability of such complexes. Additionally, the temperature and mechanical factors (pressure, shearing rate, and time) have an influence on phase separation and time stability of the system. The protein-polysaccharide complexes exhibit better functional properties than that of the proteins and polysaccharides alone. This improvement could be attributed to the simultaneous presence of the two biopolymers, as well as the structure of the complexes. Consequently, the interesting hydration (solubility, viscosity), structuration (aggregation, gelation) and surface (foaming, emulsifying) properties of these complexes can be used in a number of domains. Among others, these could be macromolecular purification, microencapsulation, food formulation (fat replacers, texturing agents), and synthesis of biomaterials (edible films, artificial grafts).

Biochimica et Biophysica Acta

The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta... more The effects of gum arabic, low methylated (LM) pectin or xylan at levels of 0 and 50 wt.% on beta-lactoglobulin (h-lg) digestibility were studied as well as the interactions between the two macromolecules during in vitro hydrolysis. The proteolysis was performed in a system involving a two-step hydrolysis: either pepsin alone, or pepsin followed by a trypsin/chymotrypsin (T/C) mixture in dialysis bags with molecular weight cut-offs (MWCO) 1000 or 8000 Da. Digestibility was estimated by the N release and by a SDS-PAGE electrophoresis of retentates from the two dialysis bags after hydrolysis. Turbidimetric measurements monitored the structural evolution of mixtures during the two-step hydrolysis. Results showed that h-lg was almost resistant to peptic digestion and that polysaccharides increased the N release despite a reduction of pepsin activity. This is due to the formation of electrostatic complexes between polysaccharides and h-lg, which reduced h-lg aggregation, increasing its solubility. The polysaccharides reduced significantly the h-lg T/C digestibility as determined using a dialysis bag with a MWCO 1000 Da, without a modification of their enzymatic activities. No significant effect of polysaccharides on the h-lg digestibility was detected using the dialysis bag with a MWCO 8000 Da. The electrophoresis pattern did not show differences in the profile of retentates in relation with the dialysis bag used. This suggests that non-specific interactions could occur during the second step of hydrolysis between polysaccharides and amino acids or peptides smaller than 8000 Da. D

Revue Française d Allergologie et d Immunologie Clinique

ABSTRACT

Cahiers de Nutrition et de Diététique, 2004

Food Hydrocolloids, 2015

Acacia gum is a natural arabinogalactan-protein type polysaccharide widely used in industrial app... more Acacia gum is a natural arabinogalactan-protein type polysaccharide widely used in industrial applications. The two varieties of Acacia gum, A. senegal and A. seyal, are hyperbranched polysaccharides rich in arabinose and galactose (PRAG) mainly formed by chains of 3,6-linked b-D-Galp substituted in position 6 by side chains of 3-linked a-L-Araf. Beyond this common structure, A. senegal presented the highest degree of branching (78.2% vs. 59.2%) with more branched galactopyranoses, shorter arabinosyl side branches, and more rhamnopyranoses in terminal position. Circular dichroism experiments evidenced that both Acacia gums were partially structured into polyproline type II helices but in a lesser extent for A. senegal gum, suggesting its less structured organisation. The fingerprint of both Acacia gums and their spectral differences determined by FTIR spectroscopy were described. Analysis of HPSEC-MALLS data suggested that macromolecules of both Acacia gums adopted an ellipsoid-like conformation in solution. The average molecular weight of A. seyal macromolecules was larger than that of A. senegal ones (8.2 Â 10 5 g mol À1 vs. 6.8 Â 10 5 g mol À1 ). Nevertheless, A. seyal macromolecules appeared more compact and less viscous (R g : 17.1 nm; [h]: 16.5 mL g À1 ) than A. senegal ones (R g : 30.8 nm; [h]: 22.8 mL g À1 ). The most compact structure of A. seyal gum can be partly explained by the lowest concentration of charged sugars that induces less electrostatic repulsion, and the highest content of long arabinose side chains that may self-organize and interact between them (e.g. hydrogen bonding, steric effect, etc.). For both Acacia gums, the anisotropy of macromolecules increased with the molecular weight, however, A. senegal macromolecules were the most anisotropic ones.

Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015

ABSTRACT Coagulation of natural rubber latex suspensions into an elastic gel is the first step of... more ABSTRACT Coagulation of natural rubber latex suspensions into an elastic gel is the first step of their processing into rubber. We studied this transition under controlled acidification conditions with the aim of identifying the main parameters controlling gel formation. The onset of aggregation and the percolation events observed during continuous acidification were monitored on a large range of volume fractions by a combination of light-scattering techniques adapted to the different degrees of suspension opacity (namely, diffusing wave spectroscopy, static light scattering and turbidimetry) and by rheology. We consequently established the state diagram of NRL particles in the pH - Φv space during acidification. Within this diagram, we identified three states: a suspension, a two-phase macroscopically separated system in between a gel and a suspension, and a gel. The rheological properties of the gels were characterized as a function of the volume fraction Φv. The elastic modulus scale with Φv3.35, it shows remarkable consistency independently of the acidification kinetics and final pH.

The journal of physical chemistry. B, Jan 3, 2015

In this article, we investigated the interaction properties of wheat gliadins, properties that ar... more In this article, we investigated the interaction properties of wheat gliadins, properties that are at the basis of their functionality in wheat grain and in food matrices. We established the equation of state of our isolate by osmotic compression and characterized the concentration-induced structural transitions, from the secondary structure of proteins to the rheological properties. We evidenced three thermodynamical regimes corresponding to several structuring regimes. First, for Φ < 0.03, gliadins behave as repulsive colloids, with a positive second virial coefficient, arising presumably from their surface charge density. No intermolecular interaction was detected by FT-IR suggesting that proteins form a stable dispersion. In the second regime, the system becomes more easily compressible, i.e. less repulsive and/or more attractive. It is associated with the disappearance of β-sheet intramolecular structures of the proteins in favor of random coils / α-helix and intermolecular ...

Carbohydrate polymers, Jan 4, 2014

Arabinogalactan (AG) and arabinogalactan-protein (AGP) fractions were treated enzymatically using... more Arabinogalactan (AG) and arabinogalactan-protein (AGP) fractions were treated enzymatically using several proteases in acidic (pH 4) and alkaline (pH 7) conditions in order to go deeper insight into the structure and conformations of the two main fractions of Acacia senegal gum. Endoproteinase Glu-C, pepsin and phosphatase acid were thus used in acidic conditions while subtilisin A, pronase, trypsin, papain and proteinase K were used in alkaline conditions to cleave protein moieties of the two fractions. Structures of AG and AGP were probed using HPSEC-MALLS, small angle neutron scattering and far-UV circular dichroism. Enzymes did not affect AG fraction structure whatever the pH conditions used, highlighting the inaccessibility of the peptide backbone and the remarkable stability of this fraction in acidic and alkaline conditions. This result was in agreement with the thin oblate ellipsoid model we previously identified for the AG fraction where the 43 amino-acid residues peptide s...