Dietary fiber and the microbiota: A narrative review by a group of experts from the Asociación Mexicana de Gastroenterología.

Dietary fiber intake is one of the most influential and efficacious strategies for modulating the gut microbiota. Said fiber can be digested by the microbiota itself, producing numerous metabolites, which include the short-chain fatty acids (SCFAs). SCFAs have local and systemic functions that impact the composition and function of the gut microbiota, and consequently, human health. The aim of the present narrative review was to provide a document that serves as a frame of reference for a clear understanding of dietary fiber and its direct and indirect effects on health. The direct benefits of dietary fiber intake can be dependent on or independent of the gut microbiota. The use of dietary fiber by the gut microbiota involves several factors, including the fiber's physiochemical characteristics. Dietary fiber type influences the gut microbiota because not all bacterial species have the same capacity to produce the enzymes needed for its degradation. A low-fiber diet can affect the balance of the SCFAs produced. Dietary fiber indirectly benefits cardiometabolic health, digestive health, certain functional gastrointestinal disorders, and different diseases.

Review of the scientific evidence and technical opinion on noncaloric sweetener consumption in gastrointestinal diseases. / Revisión de la evidencia científica y opinión técnica sobre el consumo de edulcorantes no calóricos en enfermedades gastrointestinales.

The present review of noncaloric sweeteners (NCSs) by the Asociación Mexicana de Gastroenterología was carried out to analyze and answer some of the most frequent questions and concerns about NCS consumption in patients with gastrointestinal disorders, through a thorough review of the medical literature. A group of gastroenterologists and experts on nutrition, toxicology, microbiology, and endocrinology reviewed and analyzed the published literature on the topic. The working group formulated conclusions, based on the scientific evidence published, to give an opinion with respect to NCS ingestion. Current evidence does not confirm the carcinogenic potential of NCSs. However, the studies analyzed showed that saccharin could have a proinflammatory effect and that polyols can cause gastrointestinal symptoms and manifestations, depending on the dose and type of compound. The ingestion of xylitol, erythritol, sucralose, aspartame, acesulfame K, and saccharin could increase the secretion of the gastrointestinal hormones that regulate intestinal motility, and stevia and its derivatives could have a favorable effect on the percentage of liver fat. Caution should be taken in recommending aspartame consumption in patients with chronic liver disease because it reduces the ratio of branched-chain amino acids to aromatic amino acids. In addition, NCS ingestion could modify the composition of the intestinal microbiota, having an effect on gastrointestinal symptoms and manifestations. It is important to continue conducting causality studies on humans to be able to establish recommendations on NSC consumption.

Probiotic use in clinical practice: Results of a national survey of gastroenterologists and nutritionists. / Uso de probióticos en la práctica clínica: resultados de una encuesta nacional a gastroenterólogos y nutriólogos.

INTRODUCTION AND AIMS: Probiotics are effective in gastrointestinal disease management. In Mexico, there are no studies on the use and prescription of probiotics by healthcare professionals. Our aim was to evaluate probiotic use and prescription on the part of gastroenterologists and nutritionists. MATERIALS AND METHODS: An online survey questionnaire was sent to members of the Asociación Mexicana de Gastroenterología (n = 1042), the Asociación Mexicana de Nutriología (n = 220), and healthcare professionals registered at the Fourth International Symposium: Intestinal Microbiota (n = 1328). RESULTS: Response was 34% (997 questionnaires answered) and 570 (64%) of the respondents were women. Mean participant age was 36.2 years (range 18-83). Thirty-six percent of the participants were gastroenterologists, 46% were nutritionists, and 18% were chemists and microbiologists. Seventy-one percent of the respondents knew the Food and Agriculture Organization (FAO) definition of probiotics and recommended them «always¼ (64.9%), «rarely¼ (31.7%), and «never¼ (3.6%). Gastroenterologists indicated probiotics for the treatment of disease (56.5%) and nutritionists for health maintenance (39%). Ninety-seven percent of the gastroenterologists and 98% of the nutritionists evaluated probiotics as effective in gastrointestinal symptom management and considered them safe. The majority of the respondents did not know which probiotic strain was contained in the commercial probiotic product. CONCLUSIONS: The survey results showed that the participating gastroenterologists and nutritionists understood the concept of probiotics, recommended them frequently, and considered them safe. The gastroenterologists prescribed probiotics as therapeutic agents and the nutritionists to maintain health. There was a lack of knowledge about the microbial composition of the products containing probiotics available in Mexico.

The Mexican consensus on non-cardiac chest pain. / Consenso mexicano sobre dolor torácico no cardiaco.

INTRODUCTION: Non-cardiac chest pain is defined as a clinical syndrome characterized by retrosternal pain similar to that of angina pectoris, but of non-cardiac origin and produced by esophageal, musculoskeletal, pulmonary, or psychiatric diseases. AIM: To present a consensus review based on evidence regarding the definition, epidemiology, pathophysiology, and diagnosis of non-cardiac chest pain, as well as the therapeutic options for those patients. METHODS: Three general coordinators carried out a literature review of all articles published in English and Spanish on the theme and formulated 38 initial statements, dividing them into 3 main categories: (i)definitions, epidemiology, and pathophysiology; (ii)diagnosis, and (iii)treatment. The statements underwent 3rounds of voting, utilizing the Delphi system. The final statements were those that reached >75% agreement, and they were rated utilizing the GRADE system. RESULTS AND CONCLUSIONS: The final consensus included 29 statements. All patients presenting with chest pain should initially be evaluated by a cardiologist. The most common cause of non-cardiac chest pain is gastroesophageal reflux disease. If there are no alarm symptoms, the initial approach should be a therapeutic trial with a proton pump inhibitor for 2-4weeks. If dysphagia or alarm symptoms are present, endoscopy is recommended. High-resolution manometry is the best method for ruling out spastic motor disorders and achalasia and pH monitoring aids in demonstrating abnormal esophageal acid exposure. Treatment should be directed at the pathophysiologic mechanism. It can include proton pump inhibitors, neuromodulators and/or smooth muscle relaxants, psychologic intervention and/or cognitive therapy, and occasionally surgery or endoscopic therapy.

Consensus on the prevention, diagnosis, and treatment of Clostridium difficile infection. / Consenso sobre prevención, diagnóstico y tratamiento de la infección por Clostridium difficile.

In recent decades, Clostridium difficile infection (CDI) has become a worldwide health problem. Mexico is no exception, and therefore the Asociación Mexicana de Gastroenterología brought together a multidisciplinary group (gastroenterologists, endoscopists, internists, infectious disease specialists, and microbiologists) to carry out the "Consensus on the prevention, diagnosis, and treatment of Clostridium difficile infection", establishing useful recommendations (in relation to the adult population) for the medical community. Said recommendations are presented herein. Among them, it was recognized that CDI should be suspected in subjects with diarrhea that have a history of antibiotic and/or immunosuppressant use, but that it can also be a community-acquired infection. A 2-step diagnostic algorithm was proposed, in which a highly sensitive test, such as glutamate dehydrogenase (GDH), is first utilized, and if positive, confirmed by the detection of toxins through immunoassay or nucleic acid detection tests. Another recommendation was that CDI based on clinical evaluation be categorized as mild-moderate, severe, and complicated severe, given that such a classification enables better therapeutic decisions to be made. In mild-moderate CDI, oral vancomycin is the medication of choice, and metronidazole is recommended as an alternative treatment. In addition, fecal microbiota transplantation was recognized as an efficacious option in patients with recurrence or in the more severe cases of infection, and surgery should be reserved for patients with severe colitis (toxic megacolon), in whom all medical treatment has failed.

The Mexican consensus on probiotics in gastroenterology. / Consenso mexicano sobre probióticos en gastroenterología.

INTRODUCTION: Probiotics are frequently prescribed in clinical practice. Their efficacy in treating gastrointestinal disorders is supported by a significant number of clinical trials. However, the correct prescription of these agents is hampered due to a lack of knowledge of the scientific evidence and to the different presentations and microbial compositions of the probiotics that are currently available. AIM: To provide the clinician with a consensus review of probiotics and recommendations for their use in gastroenterology. MATERIALS AND METHODS: Controlled clinical trials, meta-analyses, and systematic reviews published up to 2015 were selected, using the MESH terms: probiotics, gastrointestinal diseases, humans, adults, AND children. The Delphi method was employed. Eighteen gastroenterologists treating adult patients and 14 pediatric gastroenterologists formulated statements that were voted on until agreement>70% was reached. The level of evidence based on the GRADE system was evaluated for each statement. RESULTS AND CONCLUSIONS: Eleven statements on the general concepts of probiotics and 27 statements on the use of probiotics in gastrointestinal diseases in both adults and children were formulated. The consensus group recommends the use of probiotics under the following clinical conditions: the prevention of diarrhea associated with antibiotics, the treatment of acute infectious diarrhea, the prevention of Clostridium difficile infection and necrotizing enterocolitis, the reduction of adverse events from Helicobacter pylori eradication therapy, relief from irritable bowel syndrome symptoms, the treatment of functional constipation in the adult, and the induction and maintenance of remission in patients with ulcerative colitis and pouchitis, and the treatment of covert and overt hepatic encephalopathy.

Inter-observer agreement for diagnostic classification of esophageal motility disorders defined in high-resolution manometry.

High-resolution esophageal manometry (HRM) is a recent development used in the evaluation of esophageal function. Our aim was to assess the inter-observer agreement for diagnosis of esophageal motility disorders using this technology. Practitioners registered on the HRM Working Group website were invited to review and classify (i) 147 individual water swallows and (ii) 40 diagnostic studies comprising 10 swallows using a drop-down menu that followed the Chicago Classification system. Data were presented using a standardized format with pressure contours without a summary of HRM metrics. The sequence of swallows was fixed for each user but randomized between users to avoid sequence bias. Participants were blinded to other entries. (i) Individual swallows were assessed by 18 practitioners (13 institutions). Consensus agreement (≤ 2/18 dissenters) was present for most cases of normal peristalsis and achalasia but not for cases of peristaltic dysmotility. (ii) Diagnostic studies were assessed by 36 practitioners (28 institutions). Overall inter-observer agreement was 'moderate' (kappa 0.51) being 'substantial' (kappa > 0.7) for achalasia type I/II and no lower than 'fair-moderate' (kappa >0.34) for any diagnosis. Overall agreement was somewhat higher among those that had performed >400 studies (n = 9; kappa 0.55) and 'substantial' among experts involved in development of the Chicago Classification system (n = 4; kappa 0.66). This prospective, randomized, and blinded study reports an acceptable level of inter-observer agreement for HRM diagnoses across the full spectrum of esophageal motility disorders for a large group of clinicians working in a range of medical institutions. Suboptimal agreement for diagnosis of peristaltic motility disorders highlights contribution of objective HRM metrics.

[Differences between Chicago and traditional classifications in the diagnosis of esophageal motor disorders with high-resolution manometry and topography of esophageal pressure]. / Diferencias entre las clasificaciones de Chicago y la tradicional en el diagnóstico de los trastornos motores del esófago con manometría de alta resolución y topografía de la presión esofágica.

BACKGROUND: With the introduction of high resolution manometry (HRM) and esophageal topography a novel classification (Chicago Classification) has been proposed for the diagnosis of esophageal motor disorders (EMD). Clinical differences with the traditional classification are currently under evaluation. AIM: To investigate differences between the Chicago (CC) and traditional (TC) classifications in the diagnosis of EMD. METHODS: Consecutive patients with indication for esophageal manometry were studied. HRM was performed with a 36 sensors solid-state catheter and Manoview software (V2.0).Conventional manometric tracings were analyzed by an investigator blinded to the results of HRM. Diagnosis by CC and CT were compared. RESULTS: Two hundred patients were studied, 106 (53%) of them women (53%) with a mean patient age of 43.4 (range 16 - 84) years. Preoperative evaluation for GERD 152 (76%) was the most frequent indication. Achalasia (8), scleroderma (2) and peristaltic dysfunction (60 vs. 59) were similarly diagnosed by CC and CT. Spastic disorders were more frequently identified by CC: nutcracker esophagus (NC) in 3, spastic NC in3 and segmental NC in 11 patients versus TC: NC 5. Three patients had spasm with CC and 1 with TC. Non specific motor disorder was diagnosed by TC and 2 patients had functional obstruction with CC. Hypotensive lower esophageal sphincter was identified in 63 patients with CC vs.57 with TC. CONCLUSIONS: Spastic disorders and functional obstruction were the EMD better identified by HRM and CC.

Lateral cephalometric radiograph for the planning of maxillary implant reconstruction.

OBJECTIVE: To present a simple and objective method for the planning of maxillary implant reconstruction with autogenous bone graft in maxilla atrophy. METHODS: Lateral cephalometric radiographs were performed with a metallic marker placed inside an acrylic-coated model, followed by cephalometric studies, to predict the most adequate grafting method for maxillary reconstruction in 13 edentulous patients (2 males and 11 females) whose age ranged from 27 to 47 years (mean age 37.9 years). RESULTS: It was possible to predict the type of maxillary reconstruction in all patients. Onlay graft was used in 12 patients. One patient was submitted to LeFort I reconstruction with interpositional graft. After 8 months, the patients received a total of 95 standard implants. The success rate was 94.7% with loss of five implants. Rehabilitation was performed with protocol-type prostheses. All patients have been followed for more than 18 months since osseointegration. CONCLUSIONS: This simple and objective method provided a useful contribution to maxillary reconstruction, and to the functional and aesthetic rehabilitation of the patients.

Morphometric methods to evaluate craniofacial growth: study in rabbits.

OBJECTIVES: The purpose of this study was to evaluate the reliability of direct and indirect measurement methods, with a view to standardizing morphometry instruments. METHODS: Dry skulls of 30 New Zealand rabbits were used. Measurements were made with a transparent flexible plastic ruler, an EKG calliper and a digital calliper, as well as with computerized tomography and lateral radiographs for direct and indirect analysis of distances and angles. RESULTS: The different instruments studied showed only partial agreement. CONCLUSIONS: A standardized and reliable direct or indirect morphometry method for the craniofacial skeleton of rabbits still has not been determined.