Optimisation of a batch thermal combustion method using a tube furnace oxidation system (pyrolyser) and LSC for carbon-14 determination in environmental matrices.

Accelerator mass spectrometry and benzene synthesis coupled with liquid scintillation spectrometry are often used for accurate measurements of 14C activity in the environmental matrices. Thermal oxidation is one of the methods employed for 14C determination in environmental matrices. In this method, the sample is oxidised at high temperature (600-900 °C) to convert carbon species to CO2 and trapped in an amine-based absorber for determining the activity in a liquid scintillation counting (LSC) system. In this study, the performance of a commercially available tube furnace system (pyrolyser), for batch combustion of samples, was evaluated for the determination of 14C specific activity in terrestrial biota samples. Significant improvements over the manufacturer specified method, which is primarily designed for analysis of samples with activity well above the environmental background level, was implemented to achieve accurate determination of 14C specific activity at ambient background level. In the improved method, the CO2 produced from the combustion of the sample was isolated from the combustion products through cryogenic trapping and then absorbed in the absorber (Carbo-Sorb E) through a simple off-line transfer process. This allowed (i) optimisation of CO2 absorption by the absorber (2.2477 g of CO2/10 mL), (ii) achieving good accuracy and precision in the measurements, and a minimum detectable activity value of 13 Bq kg-1C for a counting time of 300 min (7 Bq kg-1C for 1000 min), (iii) avoiding uncertainty associated with the determination of recovery of 14C in the combustion and trapping process, and (iv) elimination of the need for an independent determination of carbon content (%) for expressing the results in terms of 14C specific activity. The method is capable of yielding accurate results with a deviation of <2.4% from the target value for IAEA C3 quality assurance reference material (with a relative standard deviation of 1.40%, and relative error of 0.34%). The combined uncertainty (1σ) associated with the measurements was computed to be 3.4%. Upon optimisation, the suitability of the method for the determination of 14C specific activity in typical terrestrial biota samples of clean air region (region not affected by local anthropogenic sources) and for the quantification of a small increase in the 14C activity above ambient levels in the vicinity of a nuclear power plant is demonstrated.

Influence of multi-walled carbon nanotubes on the physico-chemical and biological responses of chitosan-based hybrid hydrogels.

Photoresponsive membranes were successfully obtained by combining chitosan (CS), poly(vinyl alcohol) (PVA) crosslinked with genipin (GEN) and filled with multi-walled carbon nanotubes (MWCNTs). It was demonstrated that adding a small quantity (0.01% w/v) of MWCNTs conferred to those nanocomposite hybrid hydrogels an outstanding photomechanical response under infrared irradiation. Moreover, it was observed that MWCNTs enhanced the crystallinity, increased the elastic modulus but did not contribute to the thermal stability of the nanocomposite hybrid hydrogels. The swelling capacity and contact angle values of these materials were modified through the addition of MWCNTs, and the offered free OH and NH2 functional groups in their current chemical structures. These functional groups - on hybrid hydrogels' surfaces - also enhanced the adhesion and proliferation of human dermal fibroblast cells, showing typical morphologies and sizes. Additionally, non-cytotoxic effects were observed for these nanocomposite hybrid hydrogels, suggesting their potential use in tissue engineering and biomedical applications. Chemical compounds studied in this article: Chitosan (PubChem CID: 71853); Polyvinyl alcohol (PubChem CID: 11199); Genipin (PubChem CID: 442424).

Asymmetrical elevation of esophagogastric junction pressure suggests hiatal repair contributes to antireflux surgery dysphagia.

The radial distribution of esophago-gastric junction (EGJ) pressures with regard to troublesome dysphagia (TDysph) after antireflux surgery is poorly understood. Before and after antireflux surgery, end-expiratory and peak-inspiratory EGJ pressures were measured at eight angles of 45° radial separation in patients with reflux disease. All 34 patients underwent posterior crural repair, then either 90° anterior (N = 13) or 360° fundoplication (N = 21). Dysphagia was assessed prospectively using a validated questionnaire (score range 0-45) and TDysph defined as a dysphagia score that was ≥5 above pre-op baseline. Compared with before surgery, for 90° fundoplication, end-expiratory EGJ pressures were highest in the left-anterolateral sectors, the position of the partial fundoplication. In other sectors, pressures were uniformly elevated. Compared with 90° fundoplication, radial pressures after 360° fundoplication were higher circumferentially (P = 0.004), with a posterior peak. Nine patients developed TDysph after surgery with a greater increase in end-expiratory and peak-inspiratory EGJ pressures (P = 0.03 and 0.03, respectively) and significantly higher inspiratory pressure at the point of maximal radial pressure asymmetry (P = 0.048), compared with 25 patients without TDysph. Circumferential elevation of end-expiratory EGJ pressure after 90° and 360° fundoplication suggests hiatal repair elevates EGJ pressure by extrinsic compression. The highly localized focal point of elevated EGJ pressure upon inspiration in patients with TDysph after surgery is indicative of a restrictive diaphragmatic hiatus in the presence of a fundoplication.

Development of an electrochemical biosensor for the determination of triglycerides in serum samples based on a lipase/magnetite-chitosan/copper oxide nanoparticles/multiwalled carbon nanotubes/pectin composite.

A very sensitive electrochemical biosensor to determine totals triglycerides (TGs) in serum samples has been developed. It is based on the electrochemical oxidation of glycerol at glassy carbon electrodes modified with magnetic nanoparticles bonded to lipase enzyme and copper oxide nanoparticles, both supported on a multiwalled carbon nanotubes/pectin dispersion. Glycerol is produced by enzymatic reaction between the TGs present in samples and the lipase immobilized. The quantification of triglycerides was performed by amperometric measurements. The proposed electrochemical biosensor improves the performance of others methods developed for the TGs quantification. The determination of TGs does not need a pretreatment of serum samples. The PLS-1 algorithm was used for the quantification of TGs. According to this algorithm, the of detection and quantification limits were from 3.2 × 10-3 g L-1 to 3.6 × 10-3 g L-1, and from 9.6 × 10-3 to 1.1 × 10-2 g L-1, respectively. The sensitivity was 1.64 × 10-6 A L g-1. The proposed electrochemical biosensor exhibited a very good performance, a stability of 20 days, very good reproducibility and repeatability, and it is presented as a very good alternative for the determination of TGs in human serum clinical samples.

Increased homocysteine plasma levels in breast cancer patients of a Mexican population.

AIM: Hyperhomocysteinemia has been associated with different pathologies, including cardiovascular diseases, hypertension, diabetes, and breast cancer (BC). To examine the differences in total homocysteine (tHcy) plasma levels, we compared healthy women to BC patients from a Mexican population. MATERIALS AND METHODS: The tHcy plasma levels were measured using high-performance liquid chromatography with a fluorescence detector in 89 female controls and 261 BC patients. RESULTS: The observed plasma tHcy levels were significantly higher among the BC patients (11.1019 ± 5.9161 µmol/l) compared to the controls (9.1046 ± 1.3213 µmol/l) (p = 0.002), and these differences were evident when stratified by age (≥ 50 years old), menopause status, overweight and obesity, miscarriages, node metastases, progression, subtype classification (luminal, Her2 and triple negative) and nonresponse to chemotherapy. CONCLUSIONS: The tHcy plasma levels could be a good marker for the progression and chemosensitivity of BC in the analyzed sample from a Mexican population.

Natural and artificial radionuclides in a marine core. First results of 236U in North Atlantic Ocean sediments.

There are very few data available of 236U in marine sediment cores. In this study we present the results from the first oceanic depth profile of 236U in a sediment core sampled in the North Atlantic Ocean, at the PAP site (4500 m depth, Porcupine Abyssal Plain (PAP) site, 49°0' N, 16°30' W). Additionally, the sediment core was radiologically characterized through the measurement of anthropogenic 137Cs, 239Pu, 240Pu, 129I and 14C and natural 210Pb, 40K and 226Ra. The measured 236U concentrations decrease from about 90·106 at g-1 at the seafloor down to 0.5·106 at g-1 at 6 cm depth. They are several orders of magnitude lower than the reported values for soils from the Northern Hemisphere solely influenced by global fallout (i.e. from 2700·106 to 7500·106 at g-1). 236U/238U atom ratios measured are at least three orders of magnitude above the estimated level for the naturally occurring dissolved uranium. The obtained inventories are 1·1012 at m-2 for 236U, 80 Bq m-2 for 137Cs, 45 Bq m-2 for 239+240Pu and 2.6·1012 at m-2 for 129I. Atomic ratios for 236U/239Pu, 137Cs/236U and 129I/236U, obtained from the inventories are 0.036, 0.11 and 2.5 respectively. Concentration profiles show mobilization probably due to bioturbation from the abundant detritivore holothurian species living at the PAP site sea-floor. The range of 236U, 137Cs, 239+240Pu and 129I values, inventories and ratios of these anthropogenic radionuclides are more similar to the values due to fall-out than values from a contribution from the Nuclear Fuel Reprocessing Plants dispersed to the south-west of the North Atlantic Ocean. However, signs of an additional source are detected and might be associated to the nuclear wastes dumped on the Eastern North Atlantic Ocean.

Influence of natural and synthetic crosslinking reagents on the structural and mechanical properties of chitosan-based hybrid hydrogels.

The objective of this work was to correlate the physical and chemical properties of chitosan/poly(vinyl alcohol)/genipin (CS/PVA/GEN) and chitosan/poly(vinyl alcohol)/glutaraldehyde (CS/PVA/GA) hydrogels with their structural and mechanical responses. In addition, their molecular structures were determined and confirmed using FTIR spectroscopy. The results indicated that the hybrid hydrogels crosslinked with genipin showed similar crystallinity, thermal properties, elongation ratio and structural parameters as those crosslinked with glutaraldehyde. However, it was found that the elastic moduli of the two hybrid hydrogels were slightly different: 2.82±0.33MPa and 2.08±0.11MPa for GA and GEN, respectively. Although the hybrid hydrogels crosslinked with GEN presented a lower elastic modulus, the main advantage is that GEN is five to ten thousand times less cytotoxic than GA. This means that the structural and mechanical properties of hybrid hydrogels crosslinked with GEN can easily be tuned and could have potential applications in the tissue engineering, regenerative medicine, food, agriculture and environmental industries.

Mechanical and structural response of a hybrid hydrogel based on chitosan and poly(vinyl alcohol) cross-linked with epichlorohydrin for potential use in tissue engineering.

The development and characterization of a hybrid hydrogel based on chitosan (CS) and poly(vinyl alcohol) (PVA) chemically cross-linked with epichlorohydrin (ECH) is presented. The mechanical response of these hydrogels was evaluated by uniaxial tensile tests; in addition, their structural properties such as average molecular weight between cross-link points (Mcrl), mesh size (DN), and volume fraction (v(s)) were determined. This was done using the equivalent polymer network theory in combination with the obtained results from tensile and swelling tests. The films showed Young's modulus values of 11 ± 2 MPa and 9 ± 1 MPa for none irradiated and ultraviolet (UV) irradiated hydrogels, respectively. The cell viability was assessed using Calcein AM and Ethidium homodimer-1 assay and environmental scanning electron microscopy. The 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan thiazolyl blue formazan (MTT Formazan assay) results did not show cytotoxic effects; this was in good agreement with nuclear magnetic resonance and fourier transform infrared spectroscopies; their results did not show traces of ECH. This indicated that after the crosslinking process, there was no free ECH; furthermore, any possibility of ECH release in the construct during cell culture was discarded. The CS-PVA-ECH hybrid hydrogel allowed cell growth and extracellular matrix formation and showed adequate mechanical, structural, and biological properties for potential use in tissue engineering applications.

Evaluation of mechanical behavior of soft tissue by means of random laser emission.

We demonstrate the use of random laser emission for mechanical testing of bovine pericardium. An apparatus designed for tensile tests of soft and thin materials, incorporating optical and mechanical devices, allows for obtaining the mechanical behavior of the tissue samples. Using both, digital image correlation (DIC) and random laser emission analysis, the apparatus provides information regarding the response of the bovine pericardium under different stress levels. Our results show that changes in the spectral features of the random laser correlate well to the mechanical response obtained with conventional uniaxial tensile analysis coupled with DIC. Furthermore, parameters such as the shear and Young moduli are consistent with values reported previously and obtained with other techniques. Changes at the microstructural level of the tissue may thus be evaluated through spectral analysis of the random laser emission from biological samples.

[Intravitreal triamcinolone combined with grid laser photocoagulation for patients with cystoid macular edema and advanced diabetic retinopathy: pilot study]. / Triamcinolona intravítrea combinada con fotocoagulación láser en rejilla en pacientes con edema macular quístico y retinopatía diabética avanzada: estudio piloto.

BACKGROUND: To determine if primary intravitreal injection of triamcinolone acetonide (TA) plus grid laser photocoagulation (GLP) is effective in treating cystoid diabetic macular edema (DME). METHODS: Prospective comparative non-randomized clinical trial. Fourteen eyes (14 patients) diagnosed with cystoid DME were treated with GLP according to the Early Treatment Diabetic Retinopathy Study (ETDRS) guidelines, plus an intravitreal injection of 4 mg of TA. A matched control group (16 eyes [16 patients]) treated with GLP was selected retrospectively from our medical records. Best-corrected visual acuity (BCVA), and quantitative change in optical coherence tomography (OCT) macular thickness were assessed. RESULTS: Mean follow up was 14.9 months (12 to 19 months). In 3 (21.4%) eyes BCVA increased > 2 ETDRS lines, in 5 (35.7%) eyes BCVA remained the same, and BCVA decreased >2 ETDRS lines in 6 (42.8%) eyes. Central macular thickness, as measured by OCT, decreased a mean of 106.2 µm (30.2%). The difference with the control group was not statistically significant (P = .2). Four (28.5%) eyes developed an increased in intraocular pressure in our study group. CONCLUSIONS: Although all of our patients showed an improvement of cystoid DME by means of OCT and fluorescein angiography, 42.8% (6 eyes) lost 2 or more lines in BCVA with primary intravitreal injection of TA plus GLP. Primary intravitreal injection of TA plus GLP may not be effective for cystoid DME at 12-months.

Reduction of compaction force in a confined bidisperse granular media.

Experiments and simulations of the compaction force in a confined binary granular mixture column were conducted. We measured the resistance force encountered by a piston pushing a vertical granular mixture in this confined arrangement. Granular mixtures with two different particle sizes were considered; the size ratio and the size fraction were both varied. An important decrease of the compaction force was found for volumetric fractions between 15% and 40% and size ratios larger than 3. By conducting some supplementary discrete element simulations, we found that the force chain network is fractured and redistributed when small particles are present. Hence we argue that the reduction of compaction force results from the redistribution of force within the granular column.

Swallowing activity assessed by ambulatory impedance-pH monitoring predicts awake and asleep periods at night.

INTRODUCTION: Voluntary muscle activity, including swallowing, decreases during the night. The association between nocturnal awakenings and swallowing activity is under-researched with limited information on the frequency of swallows during awake and asleep periods. AIM: The aim of this study was to assess nocturnal swallowing activity and identify a cut-off predicting awake and asleep periods. METHODS: Patients undergoing impedance-pH monitoring as part of GERD work-up were asked to wear a wrist activity detecting device (Actigraph(®)) at night. Swallowing activity was quantified by analysing impedance changes in the proximal esophagus. Awake and asleep periods were determined using a validated scoring system (Sadeh algorithm). Receiver operating characteristics (ROC) analyses were performed to determine sensitivity, specificity and accuracy of swallowing frequency to identify awake and asleep periods. RESULTS: Data from 76 patients (28 male, 48 female; mean age 56 ± 15 years) were included in the analysis. The ROC analysis found that 0.33 sw/min (i.e. one swallow every 3 min) had the optimal sensitivity (78 %) and specificity (76 %) to differentiate awake from asleep periods. A swallowing frequency of 0.25 sw/min (i.e. one swallow every 4 min) was 93 % sensitive and 57 % specific to identify awake periods. A swallowing frequency of 1 sw/min was 20 % sensitive but 96 % specific in identifying awake periods. Impedance-pH monitoring detects differences in swallowing activity during awake and asleep periods. Swallowing frequency noticed during ambulatory impedance-pH monitoring can predict the state of consciousness during nocturnal periods.

Protocolo para el análisis funcional de prótesis para pacientes con amputación parcial de pie / Protocol for the Functional Analysis of Prosthesis in Patients with Partial Foot Amputation

En la actualidad el desarrollo de prótesis presenta problemas que aún no se han solucionado por completo. A pesar de que se han desarrollado varios estudios enfocados a evaluar el funcionamiento de las prótesis, los trabajos que se presentan en la literatura se realizan con suposiciones de carga, de materiales, e incluso se practican bajo condiciones estáticas. La técnica de correlación de imágenes digitales ha sido útil en diversas aplicaciones, pero ha sido poco explorada en el ambiente de las prótesis. En este trabajo se presenta una técnica capaz de medir la deformación real en sistemas protésicos de pacientes amputados, bajo condiciones de carga y postura reales. Empleando el método de correlación de imágenes digitales es posible evaluar la prótesis del paciente sin necesidad de instrumentarla o modificarla. Además es posible conocer los principales puntos de deformación sin tener que fracturar la pieza. Con esta técnica es posible medir las principales zonas de deformación de un sistema protésico, con la ventaja de que la evaluación se pueden llevar a cabo aplicando cargas y posturas reales de un paciente en un análisis dinámico.

At present, the development of prostheses presents problems that have yet to be completely solved. Despite that various studies have been developed to evaluate the functioning of these prostheses, the works presented in the literature are conducted with suppositions of burden, of materials, and are even practiced under static conditions. The technique of Digital image correlation (DIC) has been useful in diverse applications, but has been scarcely explored in the ambience of prostheses. In this work, we present a technique capable of measuring the real deformation of prosthetic systems in patients with amputations, under real conditions of load and posture. Employing the DIC method, it is possible to evaluate a patient?s prosthesis without the need for instrumenting or modifying it. In addition, it is possible to know the main points of deformation without having to ultimate load the piece. With this technique, it is possible to measure the prosthetic system?s main deformation zones, with the advantage that evaluation can be performed applying the real loads and postures of a patient in a dynamic analysis.

[Colorectal polyps: update on diagnosis]. / Pólipos colorectales: actualización en el diagnóstico.

Histological diagnosis determines the clinical behavior of colorectal polyps. Recently new types of polyps have been described and the classification has become wider and more complex. Our aim is update the current concepts in the knowledge of colorectal polyps.

Pólipos colorectales: actualización en el diagnóstico / Colorectal polyps: update in the diagnosis

El diagnóstico histológico de los pólipos colorrectales determina la conducta que tomará el médico especialista con el paciente. Con la aparición de nuevos pólipos en los últimos años, la clasificación histológica se ha tornado más compleja y amplia. Nuestro objetivo es actualizar los conceptos en el diagnóstico histológico de pólipos de colon de una manera clara y de fácil comprensión, especialmente para gastroenterólogos y patólogos.

Histological diagnosis determines the clinical behavior of colorectal polyps. Recently new types of polyps have been described and the classification has become wider and more complex. Our aim is update the current concepts in the knowledge of colorectal polyps.

Incremento de linfocitos intraepiteliales en pacientes con sindrome de intestino irritable / Increase of intraepithelial lymphocytes in patients with irritable bowel syndrome

Diversos trabajos reportan aumento en el número de linfocitos intraepiteliales (LIE), mastocitos y células enterocromafines en pacientes con Sindrome de Intestino Irritable (SII). Muchos de estos hallazgos se basan en el uso de inmunohistoquímica que son de poca disponibilidad en hospitales generales. El objetivo del presente trabajo es estudiar los hallazgos histológicos en la biopsia de colon sólo con histoquimica en pacientes con SII comparándolos con un grupo sin SII. Fueron incluidos 25 pacientes: 16 (64%), con criterios diagnósticos de SII y 9 (36%), sin SII. Se encontró un mayor número de LIE en el grupo de SII (p=0,002). Un grupo de pacientes con criterios Roma III (41,9%) presentó LIE en el rango de Colitis Linfocitica por lo que fueron excluidos de este estudio. No se encontró diferencia estadísticamente significativa en el número de mastocitos, células enterocromafines y eosinofilos.

Several studies have shown increased numbers of intraepithelial lymphocytes (IEL), mast cells, enterochromaffin cells in colonic mucosa of patients with Irritable Bowel Syndrome (IBS). Many of these findings are based is based on immunohistochemistry results, which is not available in general hospitals. Our objective is to study the histological findings observed in colon biopsies from patients with IBS compared with a group without IBS, using only histochemistry. Twenty five (25) patients were included: 16 with IBS and 9 without IBS. We found increased numbers of IEL in patients with IBS (p=0,002). A group of patients with IBS(41.9%) who fulfilled histological criteria for lymphocytic colitis were excluded. There was no significant difference in mast cells, enterochromaffin cells or eosinophils.

[Increase of intraepithelial lymphocytes in patients with irritable bowel syndrome]. / Incremento de Linfocitos Intraepiteliales en Pacientes con Sindrome de Intestino Irritable.

Several studies have shown increased numbers of intraepithelial lymphocytes (IEL), mast cells, enterochromaffin cells in colonic mucosa of patients with Irritable Bowel Syndrome (IBS). Many of these findings are based is based on immunohistochemistry results, which is not available in general hospitals. Our objective is to study the histological findings observed in colon biopsies from patients with IBS compared with a group without IBS, using only histochemistry. Twenty five (25) patients were included: 16 with IBS and 9 without IBS. We found increased numbers of IEL in patients with IBS (p=0,002). A group of patients with IBS (41.9%) who fulfilled histological criteria for lymphocytic colitis were excluded. There was no significant difference in mast cells, enterochromaffin cells or eosinophils.

Autonomic neuropathy is associated with impairment of dynamic cerebral autoregulation in type 1 diabetes.

HYPOTHESIS: The mechanisms underlying impairment of dynamic cerebral autoregulation in diabetes are not well known. Cardiovascular autonomic neuropathy (CAN) could contribute to dynamic cerebral autoregulation impairment. In this study, we assessed the association between CAN and impairment of dynamic cerebral autoregulation in patients with type 1 diabetes. METHODS: We evaluated dynamic cerebral autoregulation (DCA) in patients with type 1 diabetes and no history of cerebrovascular disease. DCA was assessed with transcranial Doppler using the correlation coefficient index Mx method. Mx was calculated from slow changes in mean cerebral blood flow velocity and mean arterial blood pressure. Increase in Mx indicates weaker DCA, with a threshold for impaired DCA above 0.3. Moderate CAN was defined as reduced heart rate variability (HRV) on the following tests: deep controlled breathing, Valsalva maneuver or initiation of active standing. Severe CAN was defined as reduced HRV associated with orthostatic hypotension. RESULTS: 60 patients were included (M/F: 33/27; mean age ± SD: 46 years ± 11.5). 23 patients had moderate CAN and 15 patients severe CAN. DCA was impaired in 37 patients. CAN was associated with impaired DCA (p = 0.005). Impairment of DCA was more pronounced in patients with severe CAN (p = 0.019). Glycosylated haemoglobin (HbA1c) was associated with impaired DCA in univariate analysis (p = 0.05). In multivariate analysis, only CAN was associated with impaired DCA (p = 0.007) whereas HbA1c was not (p = 0.161). CONCLUSIONS: CAN was associated with impaired DCA in type 1 diabetes. The magnitude of DCA impairment increased with the severity of CAN.

The micromechanical behavior of lyophilized glutaraldehyde-treated bovine pericardium under uniaxial tension.

The micromechanical behavior of lyophilized glutaraldehyde bovine pericardium undergoing uniaxial tension was studied by digital image correlation. The experiments were conducted simultaneously at macromechanical and micromechanical levels, to correlate the mechanical response of this biomaterial at different scales. From the experiments, displacement and force data were acquired; in addition, an image sequence of each sample surface was registered with a high-definition camera. With the images, it was possible to obtain the vector displacement field between pairs of images and then the in-plane strain was calculated. The secant and final moduli of this material were obtained at macromechanical and micromechanical levels. A good agreement between the micro and macro moduli was observed. This analysis is a useful alternative technique for studying this biomaterial when local properties are needed for medical applications.

Low serological positivity in patients with histology compatible with celiac disease in Perú.

OBJECTIVE: To study the frequency of positive serology for celiac disease (CD) in patients with duodenal biopsies suggestive of this disease. MATERIAL AND METHODS: Cross sectional study. We included patients with duodenal biopsies histologically compatible with CD and antigliadin, antiendomysial and IgA antitransglutaminase antibodies. We defined a "case" of CD if there was a positive biopsy and either antiendomisial or antitransglutaminase positive antibodies. RESULTS: Thirty one patients were included in our study. Six were antiendomysial positive and 5 antitransglutaminase positive while the antigliadin was positive in 14 cases. Therefore, out of 31 patients only 10 had a serology compatible with CD and only one had positive both antibodies, antiendomysial and antitransglutaminase. CONCLUSIONS: a) We have found that most of the duodenal biopsies compatible with CD are not diagnosed with positive serology; and b) we found a low correlation between serological diagnostic tests.