Non-invasive smooth muscle electromyography (SMEMG) as a novel monitoring technology of the gastrointestinal tract of awake, free-moving pigs—A pilot study

Katalin Nagy; Hedvig Fébel; George Bazar; György Grosz; Róbert Gáspár; Kálmán Ferenc Szűcs; Tamás Tóth

doi:10.1371/journal.pone.0257311

Peer Review History

Original SubmissionJanuary 31, 2021
16 Jun 2021 Decision Letter - Ewa Tomaszewska, Editor PONE-D-21-03411 Non-invasive smooth muscle electromyography (SMEMG) as a novel monitoring technology of the gastrointestinal tract of awake, free-moving pigs – a pilot study PLOS ONE Dear Dr. George Bazar, Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. Please submit your revised manuscript by July 15 2021 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file. Please include the following items when submitting your revised manuscript: A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'. A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'. An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'. If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter. If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols. Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols. We look forward to receiving your revised manuscript. Kind regards, Ewa Tomaszewska, DVM Ph.D Academic Editor PLOS ONE Journal Requirements: When submitting your revision, we need you to address these additional requirements. 1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf 2. Thank you for stating the following in the Competing Interests section: "The Authors have declared that no competing interest exist." We note that one or more of the authors are employed by a commercial company: ADEXGO Kft, MSB-MET Kft. 2.1. Please provide an amended Funding Statement declaring this commercial affiliation, as well as a statement regarding the Role of Funders in your study. If the funding organization did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript and only provided financial support in the form of authors' salaries and/or research materials, please review your statements relating to the author contributions, and ensure you have specifically and accurately indicated the role(s) that these authors had in your study. You can update author roles in the Author Contributions section of the online submission form. Please also include the following statement within your amended Funding Statement. “The funder provided support in the form of salaries for authors [insert relevant initials], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the ‘author contributions’ section.” If your commercial affiliation did play a role in your study, please state and explain this role within your updated Funding Statement. 2.2. Please also provide an updated Competing Interests Statement declaring this commercial affiliation along with any other relevant declarations relating to employment, consultancy, patents, products in development, or marketed products, etc. Within your Competing Interests Statement, please confirm that this commercial affiliation does not alter your adherence to all PLOS ONE policies on sharing data and materials by including the following statement: "This does not alter our adherence to PLOS ONE policies on sharing data and materials.” (as detailed online in our guide for authors http://journals.plos.org/plosone/s/competing-interests) . If this adherence statement is not accurate and there are restrictions on sharing of data and/or materials, please state these. Please note that we cannot proceed with consideration of your article until this information has been declared. Please include both an updated Funding Statement and Competing Interests Statement in your cover letter. We will change the online submission form on your behalf. Please know it is PLOS ONE policy for corresponding authors to declare, on behalf of all authors, all potential competing interests for the purposes of transparency. PLOS defines a competing interest as anything that interferes with, or could reasonably be perceived as interfering with, the full and objective presentation, peer review, editorial decision-making, or publication of research or non-research articles submitted to one of the journals. Competing interests can be financial or non-financial, professional, or personal. Competing interests can arise in relationship to an organization or another person. Please follow this link to our website for more details on competing interests: http://journals.plos.org/plosone/s/competing-interests [Note: HTML markup is below. Please do not edit.] Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #1: Partly Reviewer #2: Partly ******** 2. Has the statistical analysis been performed appropriately and rigorously? Reviewer #1: Yes Reviewer #2: I Don't Know ****** 3. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #1: Yes Reviewer #2: No ****** 4. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #1: Yes Reviewer #2: Yes ****** 5. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #1: The gastrointestinal tract has multifold tasks of ingesting, processing, and assimilating nutrients and disposing of wastes at appropriate times. These tasks are facilitated by several stereotypical motor patterns that build upon the intrinsic rhythmicity of the smooth muscles that generate phasic contractions in many regions of the gut. Phasic contractions timed by the occurrence of slow waves provide the basis for motility patterns such as gastric peristalsis and segmentation. The method used allowed for the assessment or measurement of the electrical activity of the muscles. However, she did not consider what the test result was about, what osbzar the obtained results were from, etc. There is no information of a slow wave or electrical discharges. It is not known at what stage of the MMC the analysis was performed and this is important. A number of biochemical and endocrinological factors play an important role in the regulation of electrical activity, there is no post-postal research in this field. No information is available on this. Reviewer #2: The authors presented an interesting article analyse myoelectric signals of the different GIT segments in growing and awake pigs and investigate the effect of fibre-rich nutrition on the GIT activity of pigs. Authors used non-invasive method for the measurement myoelectrical activity of stomach, small intestine and large intestine. After analyzing the manuscript, several questions were raised: 1. The authors report that “two diets (control and experimental) were administered in an alternating manner in four iterative cycles, each comprising an adaptation period (five days) and measuring day.” while in the table the results are presented as the absolute value for individual animals I think that authors estimated maximum of power spectrum density -minimum twice for each diet. I think that multiple measurements during the day (“measuring days” lasted for 4 hours per animal) make it possible to present the results as mean values for individual animals 2. The control diet (CTR) contained a low level of crude fibre (CF; 29 g/kg as in feed) while the experimental diet (EXP) had an increased CF content (49 g/kg as in feed). In table 1 there can be observed Fibre source - only for experimental diet on the level 38.60 and without fibre source for control diet. It seems that the sources of fiber in the control and experimental groups should be similar and differ only in the amount. ****** 6. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #1: No Reviewer #2: No [NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.] While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step. https://doi.org/10.1371/journal.pone.0257311.r001
Revision 1
16 Jul 2021 Author Response Response to Reviewers’ Comments and Suggestions PONE-D-21-03411 Non-invasive smooth muscle electromyography (SMEMG) as a novel monitoring technology of the gastrointestinal tract of awake, free-moving pigs – a pilot study PLOS ONE The authors would like to thank both the Editor and the Reviewers for considering the manuscript. All comments and recommendations have been thankfully accepted and corrections have been made accordingly. The changes are highlighted with Track Changes in the revised version of the manuscript. Please find our specific replies below. Reviewer #1: The method used allowed for the assessment or measurement of the electrical activity of the muscles. However, she did not consider what the test result was about, what osbzar the obtained results were from, etc. Thank you for the comment of the Reviewer, however it is not clear for us what is the main point of this special note. The word “osbzar” is an obvious typo, but unfortunately, we cannot figure out the meaning of it. Regarding the consideration of the test results, we can say that the whole manuscript is about the explanation of the test results, so it is not clear for us what is the point here raised by the Reviewer. We kindly ask the Reviewer to give clear description about the concerns raised against our manuscript. In the Introduction part of the manuscript, we described in detail the main objectives of the work and previous problems. There is no information of a slow wave or electrical discharges. The slow wave response was revealed on Figure 3, the whole methodological background is already published in our earlier manuscripts that are all cited in our recent publications (Szűcs KF, Nagy A, Grosz G, Tiszai Z, Gáspár R. Correlation between slow-wave myoelectric signals and mechanical contractions in the gastrointestinal tract: Advanced electromyographic method in rats. J Pharmacol Toxicol Methods. 2016;82: 37–44. doi:10.1016/j.vascn.2016.07.005; Szűcs KF, Grosz G, Süle M, Sztojkov-Ivanov A, Ducza E, Márki A, et al. Detection of stress and the effects of central nervous system depressants by gastrointestinal smooth muscle electromyography in wakeful rats. Life Sci. 2018;205: 1–8. doi:10.1016/j.lfs.2018.05.015). From these citations the Reviewer can get a wider insight to this methodology, but we cannot involve these earlier results into the current manuscript to avoid plagiarism. Since we filter out the fast electrical discharges during our record (previously we proved that these fast responses do not have significant impact on the mechanical contraction forces), therefore the slow electrical discharges are recorded as slow waves, only. It is not known at what stage of the MMC the analysis was performed and this is important. During our experiments we did 4-hour periods of measurements from 7 a.m. or 12.00 p.m. Since the animals have not been fasted, the stages of the MMC have no significance during the detection. Our aim was to measure the fed-induced alterations in the GI tract after meals. It is obvious that the MMC may had a contribution to the shape and frequency of slow waves, but their stages cannot be detectable clearly as it could be during/after fasting. Additionally, the 4-hour periods of detection very probably include the whole period of an MMC, thus we got a sum response instead of response of given stages. We think that our methods have higher practical importance providing a better insight to the effect of different fed on the GI tract motility in pigs. A number of biochemical and endocrinological factors play an important role in the regulation of electrical activity, there is no post-postal research in this field. No information is available on this. Thank you for this comment and we deeply agree that there are lots of factor that may modify the electric activity of the GI smooth muscle. However, such biochemical and endocrinological studies were not in the main scope of the study. Looking at Table 1 it becomes obvious that the main difference between the control and the test diet is the fiber content: the control diet did not contain any additional fiber sources while the test diet had added fiber content (Opticell C5 concentrated fibre source: crude fibre: 660 g/kg DM, NDF: 854 g/kg DM, ADF: 725 g/kg DM, ADL: 82 g/kg DM, Agromed Austria GmbH, Kremsmünster, Austria). Since the participating barrow pigs were in a self-control study without significant endocrinological alterations, and the fiber itself has low impact on endocrinological and biochemical modifications (especially within a 5-day diet), therefore we do not think that the above mentioned factors should be measured in this special experiments. Reviewer #2 The authors presented an interesting article analyse myoelectric signals of the different GIT segments in growing and awake pigs and investigate the effect of fibre-rich nutrition on the GIT activity of pigs. Authors used non-invasive method for the measurement myoelectrical activity of stomach, small intestine and large intestine. Thank you very much for this comment. The authors report that “two diets (control and experimental) were administered in an alternating manner in four iterative cycles, each comprising an adaptation period (five days) and measuring day.” while in the table the results are presented as the absolute value for individual animals I think that authors estimated maximum of power spectrum density -minimum twice for each diet. I think that multiple measurements during the day (“measuring days” lasted for 4 hours per animal) make it possible to present the results as mean values for individual animals. Thank you for this comment and we would like to clarify this. In the Table 2 the presented results are mean values of the maximum of power spectrum density (PsDmax, mV2) changes for each individual animal (animal, 1, 2, …9). However, the Figure 4 shows the mean values of PsDmax of the control and experimental animals (n=9) examined in the test. The relevant section has been improved in the manuscript accordingly. The control diet (CTR) contained a low level of crude fibre (CF; 29 g/kg as in feed) while the experimental diet (EXP) had an increased CF content (49 g/kg as in feed). In table 1 there can be observed Fibre source - only for experimental diet on the level 38.60 and without fibre source for control diet. It seems that the sources of fiber in the control and experimental groups should be similar and differ only in the amount. The Table 1 shows that the main difference between the control and the experimental diet is the fiber content (29 g/kg as in feed vs. 49 g/kg as in feed, respectively): the control diet did not contain any additional fiber sources while the experimental diet had added fiber content (named “Opticell C5” with crude fibre: 660 g/kg DM, NDF: 854 g/kg DM, ADF: 725 g/kg DM, ADL: 82 g/kg DM, producer: Agromed Austria GmbH, Kremsmünster, Austria). We chose this kind of fiber source in our experiment because, (1) it is widely used in pig compound feeds in Europe, and (2) the crude fiber and fiber fractions (NDF, ADF) content of the product is constant and guaranteed. The used fiber source is also free of mycotoxins and other contaminants (e.g. heavy metals). At the beginning of the experiment, the most important nutrient content of the raw materials, including the fiber source, was evaluated in a proximate analysis. With the help of this concentrated fiber source, we had the opportunity to significantly increase the fiber content of the basic (control) compound feed without any differences in the main nutrients (such as protein, ether extract, minerals, and ileal digestible amino acids content) and energy content. The pigs in the experiment consumed the control and/or experimental diets without any residual feed (and every week the fed diets were adjusted to their body weight). Therefore, the differences (the absolute value of the maximum of power spectrum density) obtained in the experiment are solely due to the increased fiber (plus NDF and ADF-cellulose and hemicellulose) content of the test diet. The relevant section in the Materials and Methods has been extended with this explanation. We thank once again the reviewers for their valuable comments that helped to improve the quality of our manuscript. Attachments Attachment Submitted filename: Response_to_Reviewers.docx https://doi.org/10.1371/journal.pone.0257311.r002
31 Aug 2021 Decision Letter - Ewa Tomaszewska, Editor Non-invasive smooth muscle electromyography (SMEMG) as a novel monitoring technology of the gastrointestinal tract of awake, free-moving pigs – a pilot study PONE-D-21-03411R1 Dear Dr. George Bazar, We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements. Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication. An invoice for payment will follow shortly after the formal acceptance. To ensure an efficient process, please log into Editorial Manager at http://www.editorialmanager.com/pone/, click the 'Update My Information' link at the top of the page, and double check that your user information is up-to-date. If you have any billing related questions, please contact our Author Billing department directly at authorbilling@plos.org. If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org. Kind regards, Ewa Tomaszewska, DVM Ph.D Academic Editor PLOS ONE Additional Editor Comments (optional): Reviewers' comments: Reviewer's Responses to Questions Comments to the Author 1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation. Reviewer #2: All comments have been addressed ******** 2. Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. Reviewer #2: Yes ****** 3. Has the statistical analysis been performed appropriately and rigorously? Reviewer #2: Yes ****** 4. Have the authors made all data underlying the findings in their manuscript fully available? The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified. Reviewer #2: Yes ****** 5. Is the manuscript presented in an intelligible fashion and written in standard English? PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here. Reviewer #2: Yes ****** 6. Review Comments to the Author Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters) Reviewer #2: The authors responded to the reviewer's previous comments in a satisfactory manner. I consider the author's' explanations sufficient for both suggestions (the "measuring days" and the comparison between the control and experimental diets) ****** 7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files. If you choose “no”, your identity will remain anonymous but your review may still be made public. Do you want your identity to be public for this peer review?** For information about this choice, including consent withdrawal, please see our Privacy Policy. Reviewer #2: No https://doi.org/10.1371/journal.pone.0257311.r003
Formally Accepted
3 Sep 2021 Acceptance Letter - Ewa Tomaszewska, Editor PONE-D-21-03411R1 Non-invasive smooth muscle electromyography (SMEMG) as a novel monitoring technology of the gastrointestinal tract of awake, free-moving pigs – a pilot study Dear Dr. Bazar: I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department. If your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org. If we can help with anything else, please email us at plosone@plos.org. Thank you for submitting your work to PLOS ONE and supporting open access. Kind regards, PLOS ONE Editorial Office Staff on behalf of Prof. Dr. Ewa Tomaszewska Academic Editor PLOS ONE https://doi.org/10.1371/journal.pone.0257311.r004

Open letter on the publication of peer review reports

PLOS recognizes the benefits of transparency in the peer review process. Therefore, we enable the publication of all of the content of peer review and author responses alongside final, published articles. Reviewers remain anonymous, unless they choose to reveal their names.

We encourage other journals to join us in this initiative. We hope that our action inspires the community, including researchers, research funders, and research institutions, to recognize the benefits of published peer review reports for all parts of the research system.

Learn more at ASAPbio .