Guide for authors

The Revista de Gastroenterología de México (Mexican Journal of Gastroenterology) is the official publication of the Asociación Mexicana de Gastroenterología (Mexican Association of Gastroenterology). Its pages are open to the members of the Association, as well as to all members of the medical community interested in using this forum to publish their articles in accordance with the following editorial policies. The journal publishes original work in the broad field of Gastroenterology and provides information on the specialty and related areas that is up-to-date and relevant. The scientific works include the areas of clinical, endoscopic, surgical, and pediatric Gastroenterology, along with related disciplines.

Editorial Committee will evaluate for publication Original Articles, Scientific Letters, Clinical Images in Gastroenterology, Brief Communications and Letters to the Editors. The journal also publishes Review articles, Clinical Guidelines, Editorials and Consensus, only at the express request of the Editorial Committee.

Manuscript preparation of Original articles

First page or title page

The title page must contain the initials of the first name(s) followed by the last name of each of the authors. Each name must be followed by superscript letters in alphabetical order that identify only the affiliations of each of the authors (names of the services, departments, and institutions they belong to, including the city, state, and country). Author’s institutional posts or positions are not to be included. The corresponding author must be indicated with an asterisk identifying him or her as such (see the examples):

Zablah^a, C.A. Velasco-Benítez^b, I. Merlos^a, S. Bonilla^c and M. Saps^d,*

^a Department of Gastroenterology and Endoscopy, Hospital Nacional de Niños Benjamín Bloom, San Salvador, El Salvador

^b Department of Pediatrics, Universidad del Valle, Cali, Colombia

^c Division of Pediatric Gastroenterology, Hepatology and Nutrition, Boston Children’s Hospital, Boston, Massachusetts, USA

^d Division of Digestive Diseases, Hepatology, and Nutrition, Nationwide Children’s Hospital, Columbus, Ohio, USA

Contact information for the corresponding author* should appear at the lower left of the fi rst page and include the author’s first and last names, address, telephone number, and email address. When a paper is sent to the Revista de Gastroenterología de México, the authors must be aware that the only offi cial form of communication between them and the Editorial Committee is by email. It is the authors’ responsibility to maintain a current and functioning email address.

Abstracts

Abstract in Spanish. All original articles must include the following sections: Introducción y objetivos, Material y métodos, Resultados, Conclusiones, a maximum of 5 keywords each separated with a semi-colon, and a Word count that should not exceed 250 words. A minimum of abbreviations is suggested.

Abstract in English. It is the authors’ responsibility to provide a title and an abstract in English that have been revised by an expert in the language. All original articles must include the following sections: Introduction and aims, Materials and methods, Results, Conclusions, and should not exceed 250 words. A maximum of 5 keywords are included at the end of the abstract, each word separated by a semi-colon. A Word count follows the Keywords. The content of the abstract should be the same in Spanish and English. A minimum of abbreviations is suggested.

Structure of the manuscript text

Introduction and aims. This section should be brief and provide only the explanation necessary for the reader to understand the text to be presented. It should include the research basis and its intent. It should not contain tables or figures. Cite only the references that are strictly necessary. The aim(s) of the work should be clearly stated and included as the final paragraph of this section.

Materials and methods. The materials utilized in the work, human or experimentation, are described here, along with their characteristics, the selection criteria, and techniques employed. Direct or bibliographic data must be provided so that the related experience can be repeated by the reader. The following of good clinical practice and animal experimentation norms must be stated. The center where the study has been conducted must be named, along with the study’s time frame or duration, patient characteristics, the selection criteria employed, and techniques used. A precise description of how the study was carried out, the type of study design, inclusion and exclusion criteria, treatment guidelines, statistical analysis, etc. will be included, providing enough details so that the experience can be repeated based on the information provided. The bibliographic search should be described in the text, together with the key words, the years covered, and the last update. All methods used, including the statistical ones, must be specifi ed. A brief description of the ethical norms followed by the researchers is given in relation to studies on humans as well as on animals. Studies on humans must have the express approval of the local ethics and clinical trial committee and be thus stated in the manuscript.

Results. The observations with the method employed are related, not interpreted, in this section. These data are explained in the text and complemented by tables and figures.

Discussion and conclusions. The authors should explain their own opinions on the topic here, emphasizing the following: 1) the significance and practical application of the results; 2) considerations as to a possible methodology inconsistency and the reasons why the results can be valid; 3) the relation to similar publications and comparison between areas of agreement and disagreement, and 4) indications and directives for future research. In addition, care should be taken that the discussion not become a review of the theme nor a repetition of the concepts that appeared in the introduction. Study results should not be repeated either. The conclusions of the study should be included as the fi nal paragraph of this section.

References

Consult the Reference preparation guidelines.

Tables

Each table should be on a separate page within the text document and numbered progressively with Arabic numerals. Include a brief title for each one and if necessary, a note, as well as the definition of the symbol(s) used. Superscript Arabic numerals should be used in footnotes in the tables. If abbreviations are used they should be defined just below the table.

Figures

Figures should be professionally designed. Clinical photographs, radiographs, and surgical specimens should only be presented in JPEG, EPS, or TIFF digital image formats in high resolution quality or its equivalent in 300 dpi. No original drawings, printed photographs of any kind, or radiographs will be accepted. If photographs of persons are sent they must preserve the individual’s anonymity or be accompanied by a letter granting permission for their use. The figures should be uploaded separately to the Editorial Manager. All figures should be cited following their descriptions in the text and numbered consecutively.

Figure legends (detailed description of each figure)

Figure legends should appear on a separate page and be doublespaced, each one beginning with an Arabic numeral. Detailed figure descriptions should be given in this section, not just simple statements that the figure is a chest or abdominal x-ray, for example. When arrows are used, identify what they are signaling. In graphs, the significance of each bar color or pattern should be indicated, as well as its statistical signifi cance, when applicable. If abbreviations are included they should be defi ned in the fi gure legends.

Preparation of Scientific letters

The Journal’s Editorial Committee will evaluate the Clinical descriptions that contain information that can be of clear educational value for the readers of the Journal. Case studies of 4 patients or fewer may be included that describe new aspects, a therapeutic challenge, treatments of pathologies with new drugs and/or relevant evaluations of the mechanisms of the disease, its diagnosis, or treatment. The maximum length is 850 words and the text should not be divided into sections. Two figures or tables may be included. The reference list should not have more tan 10 references. Scientific letters do not include an abstract. The maximum number of authors is 5.

Preparation of Clinical images in Gastroenterology

This section is for images that are of clinical interest or useful for teaching. A maximum of 5 photographs are accepted in the JPEG, EPS or TIFF digital image formats at the best possible resolution (300 dpi). The text should not exceed 15 single-spaced lines that will be used as the legends accompanying the photograph(s). Images with a maximum of 3 authors are accepted. A reference list is not required. No images printed on any kind of paper will be accepted. The Editors reserve the right to reject all images of inadequate quality or resolution. Images do not include an abstract.

Preparation of Letters to the Editors

The Revista de Gastroenterología de México accepts Letters to the Editors in relation to articles published in the Journal from the two latest issues. The Letter should have a title that refers to the article being discussed and it is the authors’ responsibility to provide the title in Spanish and English. The letter should begin with the phrase, “To the Editors: …”. It should be no longer than 500 words. The authors’ own data is acceptable if they strengthen the discussion of the article. If such is the case, a maximum of one table, figure, or illustration is allowed. There is a maximum of 5 references, including the obligatory reference of the article being discussed (previously published in the Revista de Gastroenterología de México). Consult the Reference preparation guidelines. Once the Letter to the Editors has been received, the authors of the article under discussion will be contacted to give them the opportunity to write a Letter of Response, and both will be published in the same issue of the Journal. If more than one Letter is received, all will be sent to the authors of the corresponding article so they can be answered.

Preparation of the Brief Communications

These are brief reports of preliminary or limited data corresponding to original research that is in progress, observations or case series with data on the physiopathogenesis, diagnosis, treatment, or prognostic factors of gastrointestinal, hepatic and/or pancreatic disorders. The authors are responsible for providing the title in Spanish and English. An abstract no longer than 150 words in Spanish and English must be included. The body of the article should not be longer than 1,200 words and should have only one table, fi gure, or illustration. The following sections are included: Introduction, Materials and methods, Results, and Discussion. There is also a maximum of 10 references (consult the Reference preparation guidelines).

Preparation of the Review Articles (by invitation)

These are articles that investigate, describe, and analyze the current state of knowledge on a subject of interest in Gastroenterology and related disciplines. They can be written by one or more collaborating authors, but only at the express request of the Editorial Committee. They may encompass aspects of physiopathogenesis, new diagnostic techniques, experimental treatments, emerging therapies, and new classifi cations of a nosologic entity. The abstract and text are not divided into sections. The Spanish and English abstracts should not exceed 250 words each, with a maximum of 5 keywords. Each Review article has a minimum of 5,000 words and a maximum of 7,500 words and no more than 250 references (structured as indicated in the Reference preparation guidelines). There is a maximum of 6 tables or figures.

All manuscripts must be submitted online through the Editorial Manager (EM) Web site at https://www.editorialmanager.com/rgmx/. Electronic files of the manuscript contents must be uploaded at that Web site and the onscreen steps should be followed to submit the manuscript to the Editorial Office. All manuscripts must be written in a double-spaced format using the size 12 Times New Roman font. The Guide for Authors in Spanish can be found at Normas para los autores.

The Revista de Gastroenterología de México accepts manuscripts in Spanish and English for their publication. The Journal publishes two versions, one in Spanish (printed and online formats) and one in English (online format). Accepted articles in Spanish are all translated into English and appear in the Journal’s online version. Accepted articles in English are translated into Spanish and appear in both the printed and online versions of the Journal.

Please see our information pages on Ethics in publishing and Ethical guidelines for journal publication.

Studies on patients or volunteers require ethics committee approval and informed consent, which should be documented in the paper. Appropriate consents, permissions and releases must be obtained where an author wishes to include case details or other personal information or images of patients and any other individuals in an Elsevier publication. Written consents must be retained by the author but copies should not be provided to the journal. Only if specifically requested by the journal in exceptional circumstances (for example if a legal issue arises) the author must provide copies of the consents or evidence that such consents have been obtained. For more information, please review the Elsevier Policy on the Use of Images or Personal Information of Patients or other Individuals. Unless you have written permission from the patient (or, where applicable, the next of kin), the personal details of any patient included in any part of the article and in any supplementary materials (including all illustrations and videos) must be removed before submission.

All authors must disclose any financial and personal relationships with other people or organizations that could inappropriately influence (bias) their work. Examples of potential competing interests include employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding. Authors must disclose any interests in two places: 1. A summary declaration of interest statement in the title page file (if double-blind) or the manuscript file (if single-blind). If there are no interests to declare then please state this: 'Declarations of interest: none'. This summary statement will be ultimately published if the article is accepted. 2. Detailed disclosures as part of a separate Declaration of Interest form, which forms part of the journal's official records. It is important for potential interests to be declared in both places and that the information matches. More information.

The below guidance only refers to the writing process, and not to the use of AI tools to analyse and draw insights from data as part of the research process.

Where authors use generative artificial intelligence (AI) and AI-assisted technologies in the writing process, authors should only use these technologies to improve readability and language. Applying the technology should be done with human oversight and control, and authors should carefully review and edit the result, as AI can generate authoritative-sounding output that can be incorrect, incomplete or biased. AI and AI-assisted technologies should not be listed as an author or co-author, or be cited as an author. Authorship implies responsibilities and tasks that can only be attributed to and performed by humans, as outlined in Elsevier’s AI policy for authors.

Authors should disclose in their manuscript the use of AI and AI-assisted technologies in the writing process by following the instructions below. A statement will appear in the published work. Please note that authors are ultimately responsible and accountable for the contents of the work.

Disclosure instructions
Authors must disclose the use of generative AI and AI-assisted technologies in the writing process by adding a statement at the end of their manuscript in the core manuscript file, before the References list. The statement should be placed in a new section entitled ‘Declaration of Generative AI and AI-assisted technologies in the writing process’.

Statement: During the preparation of this work the author(s) used [NAME TOOL / SERVICE] in order to [REASON]. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.

This declaration does not apply to the use of basic tools for checking grammar, spelling, references etc. If there is nothing to disclose, there is no need to add a statement.

Submission of an article implies that the work described has not been published previously (except in the form of an abstract or as part of a published lecture or academic thesis, see 'Multiple, redundant or concurrent publication' section of our ethics policy for more information), that it is not under consideration for publication elsewhere, that its publication is approved by all authors and tacitly or explicitly by the responsible authorities where the work was carried out, and that, if accepted, it will not be published elsewhere in the same form, in English or in any other language, including electronically without the written consent of the copyright-holder. To verify originality, your article may be checked by the originality detection service Crossref Similarity Check.

Please note that preprints can be shared anywhere at any time, in line with Elsevier's sharing policy. Sharing your preprints e.g. on a preprint server will not count as prior publication (see 'Multiple, redundant or concurrent publication' for more information).

Reporting guidance
For research involving or pertaining to humans, animals or eukaryotic cells, investigators should integrate sex and gender-based analyses (SGBA) into their research design according to funder/sponsor requirements and best practices within a field. Authors should address the sex and/or gender dimensions of their research in their article. In cases where they cannot, they should discuss this as a limitation to their research's generalizability. Importantly, authors should explicitly state what definitions of sex and/or gender they are applying to enhance the precision, rigor and reproducibility of their research and to avoid ambiguity or conflation of terms and the constructs to which they refer (see Definitions section below). Authors can refer to the SSex and Gender Equity in Research (SAGER) guidelines and the S SAGER guidelines checklist. These offer systematic approaches to the use and editorial review of sex and gender information in study design, data analysis, outcome reporting and research interpretation - however, please note there is no single, universally agreed-upon set of guidelines for defining sex and gender.

Definitions
Sex generally refers to a set of biological attributes that are associated with physical and physiological features (e.g., chromosomal genotype, hormonal levels, internal and external anatomy). A binary sex categorization (male/female) is usually designated at birth ("sex assigned at birth"), most often based solely on the visible external anatomy of a newborn. Gender generally refers to socially constructed roles, behaviors, and identities of women, men and gender-diverse people that occur in a historical and cultural context and may vary across societies and over time. Gender influences how people view themselves and each other, how they behave and interact and how power is distributed in society. Sex and gender are often incorrectly portrayed as binary (female/male or woman/man) and unchanging whereas these constructs actually exist along a spectrum and include additional sex categorizations and gender identities such as people who are intersex/have differences of sex development (DSD) or identify as non-binary. Moreover, the terms "sex" and "gender" can be ambiguous—thus it is important for authors to define the manner in which they are used. In addition to this definition guidance and the SAGER guidelines, the Sresources on this page offer further insight around sex and gender in research studies.

All authors should have made substantial contributions to all of the following: (1) the conception and design of the study, or acquisition of data, or analysis and interpretation of data, (2) drafting the article or revising it critically for important intellectual content, (3) final approval of the version to be submitted.

Authors are expected to consider carefully the list and order of authors before submitting their manuscript and provide the definitive list of authors at the time of the original submission. Any addition, deletion or rearrangement of author names in the authorship list should be made only before the manuscript has been accepted and only if approved by the journal Editor. To request such a change, the Editor must receive the following from the corresponding author: (a) the reason for the change in author list and (b) written confirmation (e-mail, letter) from all authors that they agree with the addition, removal or rearrangement. In the case of addition or removal of authors, this includes confirmation from the author being added or removed.
Only in exceptional circumstances will the Editor consider the addition, deletion or rearrangement of authors after the manuscript has been accepted. While the Editor considers the request, publication of the manuscript will be suspended. If the manuscript has already been published in an online issue, any requests approved by the Editor will result in a corrigendum.

Randomized controlled trials should be presented according to the CONSORT guidelines. At manuscript submission, authors must provide the CONSORT checklist accompanied by a flow diagram that illustrates the progress of patients through the trial, including recruitment, enrollment, randomization, withdrawal and completion, and a detailed description of the randomization procedure. The CONSORT checklist and template flow diagram are available online.

Upon acceptance of an article, authors will be asked to complete a 'Journal Publishing Agreement' (see more information on this). An e-mail will be sent to the corresponding author confirming receipt of the manuscript together with a 'Journal Publishing Agreement' form or a link to the online version of this agreement.

Author rights
As an author you (or your employer or institution) have certain rights to reuse your work. More information.

You are requested to identify who provided financial support for the conduct of the research and/or preparation of the article and to briefly describe the role of the sponsor(s), if any, in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the article for publication. If the funding source(s) had no such involvement then this should be stated.

This is an open access journal: all articles will be immediately and permanently free for everyone to read and download. To provide open access, this journal has an open access fee (also known as an article publishing charge APC) which needs to be paid by the authors or on their behalf e.g. by their research funder or institution. Permitted third party (re)use is defined by the following Creative Commons user licenses:

Researcher Academy is a free e-learning platform designed to support early and mid-career researchers throughout their research journey. The "Learn" environment at Researcher Academy offers several interactive modules, webinars, downloadable guides and resources to guide you through the process of writing for research and going through peer review. Feel free to use these free resources to improve your submission and navigate the publication process with ease.

Please submit your article via https://www.editorialmanager.com/rgmx/.

The editorial process includes the following phases:

1. The manuscripts are reviewed by the Administrative Editor to make sure they follow the Journal guidelines, and if they do not, they are returned to the authors to be completed.
2. Manuscripts are assigned to the Editors.
3. All manuscripts are submitted to peer review. The Editors assign the manuscript to two reviewers.
4. The reviewers may suggest the following decisions: Rejected, Accepted without Changes, Accepted with Minimal Modifications, Accepted with Major Modifications
5. Once the evaluations are received, the Editors discuss them to make their decision. The manuscripts can be Accepted immediately, they can be returned to the authors so the modifi cations suggested by the Reviewers can be carried out, or they can be Rejected. If there are differing opinions, a third Reviewer can be requested. If the Editors deem it necessary, a Technical Reviewer can be summoned, such as a statistics specialist.
6. In the case of modifications, the authors must submit a new version through the Editorial Manager (EM) within a maximum time limit of one month from the notification, together with a letter written in the “Respond to Reviewers” section of the EM, in which they give a detailed description of the modifications made, including the proposals by the Editorial Committee, as well as those indicated by the reviewers consulted. If this is not done, the work will be rejected.

This journal uses double-anonymized review, which means the identities of the authors are concealed from the reviewers, and vice versa. More information is available on our website. To facilitate this, please include the following separately:
Title page (with author details): This should include the title, authors' names affiliations, acknowledgements and any Declaration of Interest statement, and a complete address for the corresponding author including an e-mail address.
Anonymized manuscript (no author details): The main body of the paper (including the references, figures, tables and any acknowledgements) should not include any identifying information, such as the authors' names or affiliations.

It is important that the file be saved in the native format of the word processor used. The text should be in single-column format. Keep the layout of the text as simple as possible. Most formatting codes will be removed and replaced on processing the article. In particular, do not use the word processor's options to justify text or to hyphenate words. However, do use bold face, italics, subscripts, superscripts etc. When preparing tables, if you are using a table grid, use only one grid for each individual table and not a grid for each row. If no grid is used, use tabs, not spaces, to align columns. The electronic text should be prepared in a way very similar to that of conventional manuscripts (see also the Guide to Publishing with Elsevier). Note that source files of figures, tables and text graphics will be required whether or not you embed your figures in the text. See also the section on Electronic artwork.
To avoid unnecessary errors you are strongly advised to use the 'spell-check' and 'grammar-check' functions of your word processor.

Highlights are optional yet highly encouraged for this journal, as they increase the discoverability of your article via search engines. They consist of a short collection of bullet points that capture the novel results of your research as well as new methods that were used during the study (if any). Please have a look at the examples here: example Highlights.

Highlights should be submitted in a separate editable file in the online submission system. Please use 'Highlights' in the file name and include 3 to 5 bullet points (maximum 85 characters, including spaces, per bullet point).

The graphical abstract should summarize the contents of the article in a concise, pictorial form designed to capture the attention of a wide readership. Graphical abstracts should be submitted as a separate file in the online submission system. Image size: Please provide an image with a minimum of 531 × 1328 pixels (h × w) or proportionally more. The image should be readable at a size of 5 × 13 cm using a regular screen resolution of 96 dpi. Preferred file types: TIFF, EPS, PDF or MS Office files. You can view Example Graphical Abstracts on our information site.

List funding sources in this standard way to facilitate compliance to funder's requirements:

Funding: This work was supported by the National Institutes of Health [grant numbers xxxx, yyyy]; the Bill & Melinda Gates Foundation, Seattle, WA [grant number zzzz]; and the United States Institutes of Peace [grant number aaaa].

It is not necessary to include detailed descriptions on the program or type of grants and awards. When funding is from a block grant or other resources available to a university, college, or other research institution, submit the name of the institute or organization that provided the funding.

If no funding has been provided for the research, please include the following sentence:

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Whilst it is accepted that authors sometimes need to manipulate images for clarity, manipulation for purposes of deception or fraud will be seen as scientific ethical abuse and will be dealt with accordingly. For graphical images, this journal is applying the following policy: no specific feature within an image may be enhanced, obscured, moved, removed, or introduced. Adjustments of brightness, contrast, or color balance are acceptable if and as long as they do not obscure or eliminate any information present in the original. Nonlinear adjustments (e.g. changes to gamma settings) must be disclosed in the figure legend.

General points
• Make sure you use uniform lettering and sizing of your original artwork.
• Embed the used fonts if the application provides that option.
• Aim to use the following fonts in your illustrations: Arial, Courier, Times New Roman, Symbol, or use fonts that look similar.
• Number the illustrations according to their sequence in the text.
• Use a logical naming convention for your artwork files.
• Provide captions to illustrations separately.
• Size the illustrations close to the desired dimensions of the published version.
• Submit each illustration as a separate file.
• Ensure that color images are accessible to all, including those with impaired color vision.

A detailed guide on electronic artwork is available.
You are urged to visit this site; some excerpts from the detailed information are given here.

Formats
If your electronic artwork is created in a Microsoft Office application (Word, PowerPoint, Excel) then please supply 'as is' in the native document format.
Regardless of the application used other than Microsoft Office, when your electronic artwork is finalized, please 'Save as' or convert the images to one of the following formats (note the resolution requirements for line drawings, halftones, and line/halftone combinations given below):
EPS (or PDF): Vector drawings, embed all used fonts.
TIFF (or JPEG): Color or grayscale photographs (halftones), keep to a minimum of 300 dpi.
TIFF (or JPEG): Bitmapped (pure black & white pixels) line drawings, keep to a minimum of 1000 dpi.
TIFF (or JPEG): Combinations bitmapped line/half-tone (color or grayscale), keep to a minimum of 500 dpi.
Please do not:
• Supply files that are optimized for screen use (e.g., GIF, BMP, PICT, WPG); these typically have a low number of pixels and limited set of colors;
• Supply files that are too low in resolution;
• Submit graphics that are disproportionately large for the content.

Please make sure that artwork files are in an acceptable format (TIFF (or JPEG), EPS (or PDF) or MS Office files) and with the correct resolution. If, together with your accepted article, you submit usable color figures then Elsevier will ensure, at no additional charge, that these figures will appear in color online (e.g., ScienceDirect and other sites). Further information on the preparation of electronic artwork.

Please ensure that every reference cited in the text is also present in the reference list (and vice versa). Any references cited in the abstract must be given in full. Unpublished results and personal communications are not recommended in the reference list, but may be mentioned in the text. If these references are included in the reference list they should follow the standard reference style of the journal and should include a substitution of the publication date with either 'Unpublished results' or 'Personal communication'. Citation of a reference as 'in press' implies that the item has been accepted for publication.

Increased discoverability of research and high quality peer review are ensured by online links to the sources cited. In order to allow us to create links to abstracting and indexing services, such as Scopus, CrossRef and PubMed, please ensure that data provided in the references are correct. Please note that incorrect surnames, journal/book titles, publication year and pagination may prevent link creation. When copying references, please be careful as they may already contain errors. Use of the DOI is highly encouraged.

A DOI is guaranteed never to change, so you can use it as a permanent link to any electronic article. An example of a citation using DOI for an article not yet in an issue is: VanDecar J.C., Russo R.M., James D.E., Ambeh W.B., Franke M. (2003). Aseismic continuation of the Lesser Antilles slab beneath northeastern Venezuela. Journal of Geophysical Research, https://doi.org/10.1029/2001JB000884. Please note the format of such citations should be in the same style as all other references in the paper.

As a minimum, the full URL should be given and the date when the reference was last accessed. Any further information, if known (DOI, author names, dates, reference to a source publication, etc.), should also be given. Web references can be listed separately (e.g., after the reference list) under a different heading if desired, or can be included in the reference list.

This journal encourages you to cite underlying or relevant datasets in your manuscript by citing them in your text and including a data reference in your Reference List. Data references should include the following elements: author name(s), dataset title, data repository, version (where available), year, and global persistent identifier. Add [dataset] immediately before the reference so we can properly identify it as a data reference. This identifier will not appear in your published article.

Where a preprint has subsequently become available as a peer-reviewed publication, the formal publication should be used as the reference. If there are preprints that are central to your work or that cover crucial developments in the topic, but are not yet formally published, these may be referenced. Preprints should be clearly marked as such, for example by including the word preprint, or the name of the preprint server, as part of the reference. The preprint DOI should also be provided.

Most Elsevier journals have their reference template available in many of the most popular reference management software products. These include all products that support Citation Style Language styles, such as Mendeley. Using citation plug-ins from these products, authors only need to select the appropriate journal template when preparing their article, after which citations and bibliographies will be automatically formatted in the journal's style. If no template is yet available for this journal, please follow the format of the sample references and citations as shown in this Guide. If you use reference management software, please ensure that you remove all field codes before submitting the electronic manuscript. More information on how to remove field codes from different reference management software.

Reference preparation guidelines

The Editors of the Revista de Gastroenterología de México reserve the right to reject any article with incorrectly structured references. It is the responsibility of the author to make sure that the references are correctly organized and can be found by all readers.

The citation style of the Journal is the numbered Vancouver style. The references should be numbered progressively in the order in which they first appear in the text, tables and fi gures, and they should be written in Arabic numerals with no parentheses and then followed by the necessary punctuation.

Journal articles

The writing should follow the indications of the International Committee of Medical Journal Editors in the style of the Index Medicus. The list of correct abbreviations appears annually in the January issue of the Index Medicus and can also be consulted in PubMed.

All authors must be included (capitalized last names followed by first name initials in capital letters) when there are 3 or fewer. When there are more, the first 3 are named, followed by the term “et al.”

Each author’s name is separated by a “comma”(,) and the last author’s name is separated from the title of the article by a “period”(.). The title of the work must be written out completely in the original language. Journal abbreviations follow the indications in the Index Medicus and PubMed. The year of publication comes after the Journal abbreviation with no separating punctuation and it is then separated from the journal volume by a “semicolon” (;). It is not necessary to put the journal number or month of publication in those journals that publish their issues with continuous pagination. The volume should be followed by a “colon” (:) separating it from the first and last pages of the designated article. The first and last pages are hyphenated (-).

Examples:

1. Rawsthorne P, Shanahan F, Cronin NC, et al. An international survey of the use and attitudes regarding alternative medicine by patients with infl ammatory bowel disease. Am J Gastroenterol 1999;94:1298-303.
2. Lizardi-Cervera J, Vázquez-Elizondo G, Becerra-Laparra I, et al. Estudio comparativo de la presentación clínica y complicaciones de la diverticulitis aguda colónica en pacientes mayores y menores de 65 años. Rev Gastroenterol Méx 2008;73:153-8.

Book chapter

All authors must be included (capitalized last names followed by first name initials in capital letters) when there are 3 or fewer. When there are more, the first 3 are named, followed by the term “et al.”. Each author’s name is separated by a “comma” and the last author’s name is separated from the title of the chapter by a “period”. The title of the chapter must be written out completely in the original language followed by a “period” and then the Word “In” for publications in English or “En” for publications in Spanish followed by a colon (:). Include the names of the Editors in the same format as that for authors. After the last name put a “comma” (,) and the word editor(s) followed by a “period” (.). Write the title of the book followed by a “period” (.). Then write the number of the edition, if it is not the first, followed by a “period” (.), the city in which it is edited, followed by a colon (:), the name of the publisher, followed by a “semicolon” (;), the year of publication, followed by a “comma” (,), and then the abbreviation “pp.” followed by the hyphenated (-) first and last pages of the chapter.

Examples:

1. Sherman S, Lehman GA. Complications of endoscopic retrograde cholangiopancreatography and endoscopic sphincterotomy: management and prevention. In: Barkin JS, O’Phelan CA, editors. Advanced therapeutic endoscopy. New York: Raven Press; 1990, pp. 201-10.

2. Denis K, Kennett RH, Kinman N, Molinario C, Sherman L. Defining the B-cell repertoire with hybridomas derived from monoclonal fragment cultures. In: Kennett RH, McKearn TJ, Bechtol KB, editors. Monoclonal antibodies.Hybridomas: a new dimension in biological analyses. 2^nd ed. New York: Plenun Press; 1981. pp. 49-59.

The term “personal communication” should not be used. In contrast, the term “in press” may be used when the paper has already been accepted by a journal, and in that case, the name of said journal must be specified. All other cases referring to abstracts, books, conference publications, technical and scientifi c reports, newspaper articles, Internet pages, or electronic material may be consulted directly at www.nlm.nih.gov/citingmedicine/.

Elsevier accepts video material and animation sequences to support and enhance your scientific research. Authors who have video or animation files that they wish to submit with their article are strongly encouraged to include links to these within the body of the article. This can be done in the same way as a figure or table by referring to the video or animation content and noting in the body text where it should be placed. All submitted files should be properly labeled so that they directly relate to the video file's content. In order to ensure that your video or animation material is directly usable, please provide the file in one of our recommended file formats with a preferred maximum size of 150 MB per file, 1 GB in total. Video and animation files supplied will be published online in the electronic version of your article in Elsevier Web products, including ScienceDirect. Please supply 'stills' with your files: you can choose any frame from the video or animation or make a separate image. These will be used instead of standard icons and will personalize the link to your video data. For more detailed instructions please visit our video instruction pages. Note: since video and animation cannot be embedded in the print version of the journal, please provide text for both the electronic and the print version for the portions of the article that refer to this content.

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