The aim of the study was to investigate the popularity, content of Invisalign patient testimonials on YouTube, as well as the sentiment of the related comments.Using the term “Invisalign experience,” the top 100 results on YouTube by view count were screened for English spoken patient videos that attracted comments. Video information , engagement metrics , and views were collected. Videos were rated for information completeness (ICS), and comments were classified by origin and content. The emotional loading of the comments was measured using automated sentiment analysis.P = 0.03) between mean positive  and negative sentiment scores . Commenter’s status and overall comment on video were significantly associated with positive sentiment scores. There was a significant association between sponsorship, commenter’s status, overall comment on video, focus of concern, perceived Invisalign’s disadvantages, and increased negative sentiment scores.The 40 reviewed testimonials scored an average ICS of 3.78 (SD 0.97). ICS, time since upload, and video duration did not appear to significantly influence the number of views, subscriptions, likes, dislikes, and comments. There was a statistically significant difference (Engagement of audience and views of the most popular Invisalign patient testimonials were not significantly influenced by completeness of information, video duration, and lifespan. The sentiment of viewers’ comments about Invisalign treatment was significantly more positive and was significantly associated with their status, content, and sponsorship of videos. Orthodontic trends on YouTube need to be cautiously monitored for planning interventions that improve patients’ knowledge about orthodontics. Personal stories of patients in the form of narratives, testimonials, or anecdotes are increasingly becoming available to the public as YouTube videos and discussion posts on social media and peer-support groups. Such anecdotal information is heavily weighed by health consumers when making treatment choices . Health With over a billion users, YouTube is the fastest growing video sharing Web platform, ranked second in Internet traffic worldwide and in the United States (US) . The eduGiven YouTube is being largely used as a primary source of orthodontic information , it can So far, the available Invisalign information on YouTube videos uploaded by patients-vloggers and the interaction between vloggers and viewers have not been investigated. Therefore, the aims of this study were (i) to determine the completeness of information of the most viewed YouTube patient testimonials regarding Invisalign treatment and the emotional content of viewers’ comments and (ii) to evaluate the association patterns between video metrics, information completeness, and sentiment of comments.http://www.youtube.com) was searched on June 10, 2017, using the phrase “Invisalign experience.” Preliminary YouTube search using the specific search phrase delivered more relevant results than “Invisalign” and “Invisalign testimonials” and therefore selected for the study. Before searching, the computer history and cookies were deleted. No filters regarding video upload date, type, duration, and features were enabled. The initial search returned 61,300 results. To reproduce a standard YouTube search of the average user [YouTube , engagement metrics , and view metrics were recorded for all eligible videos. The description field of each video was scrutinized for sponsorship statements or endorsement deals.All videos were viewed and available information regarding clinician’s status, Invisalign cost, treatment procedure, complications and comparison between Invisalign and fixed appliances was extracted. Such information has been previously found to attract attention on social media . SubsequSentiment analysis or opinion mining is an approach that classifies comments as praise remarks or complaints and can further process these classifications into actionable areas to improve clinical practice . Sentimet test was used to compare the means of positive and negative sentiment scores. Median regression analysis was used to investigate the association between ICS and engagement and view metrics. To determine the association between positive and negative sentiment scores and sponsorship, viewer’s status, overall comment, focus of concern, and disadvantages as perceived by viewers, Pearson’s chi-squared test was used. The significance level was set at 5%. Statistical analysis was performed using a statistical software package .Paired YouTube search initially yielded 61,300 results. After screening video titles and watch pages of the first 100 videos, the list of results reduced by 19 videos  of video duration, lifespan, and engagement metrics are displayed in Table P = 0.10).The analyzed videos presented a mean ICS of 3.78 (SD 0.97). Eleven videos achieved the theoretical maximum score of 5 points. The results of median regression analysis showed no significant association between ICS, video duration, and time since upload and either engagement metrics or views Table . There wHalf of the vloggers were treated by orthodontists and 17 by dentists. Twenty-nine vloggers were in active treatment at the time the video was recorded. Most vloggers discussed treatment aspects like frequency of changing trays/practice visits, attachments, wearing time, and consultation. Procedures like ClinCheck and Interproximal Enamel Reduction (IER) were scarcely reported. Pain, tooth sensitivity, or discomfort were the most frequent side-effects reported by 22 vloggers. Eleven vloggers complained about oral symptoms, and specifically, mouth dryness and soft tissue irritation. Eleven vloggers had to adjust their dietary habits, while speech was affected (lisp) in ten cases. Fifty percent of the vloggers compared Invisalign and fixed appliances, whereas most of them (14 out of 20) did not have personal experience with braces.Commenter’s status was not specified in 234 cases, while many commenters were related to Invisalign treatment .Four hundred sixty-nine viewers did not comment on the video itself, 80 found the video useful/informative, and 31 commented on vlogger’s reliability/sponsoring. Most commenters focused on asking or sharing information about own malocclusion/treatment or even finding similarities with the vlogger’s condition, treatment cost, complications, and efficiency. Twenty-four percent of the viewers shared their view on Invisalign’s disadvantages with most of them mentioning cost, a combination of disadvantages, and pain/oral symptoms.P = 0.03) between mean positive  and negative sentiment scores . There was a significant association between commenter’s status, overall comment on video, and positive sentiment scores , the manufacturer, product promoters , and research recruiters intervened by posting comments. The interest of different viewers’ groups confirms the claimed potential of social media to monitor public response to health issues, identify misinformation, and identify targeted areas for intervention efforts .As YouTube users commonly engage in active discussion by expressing either positive or negative emotions in their messages , this stNarrative communication through social media can improve users’ learning abilities by providing ideal health role models. On the contrary, sharing information within personal stories may also hide risks, especially when acting as a deterrent for patients from visiting health professionals or the public may not know how to correctly apply online information about their personal health situation. Since videos involving patient experiences are of lower educational value than expert led ones , professThis is the first study to investigate information sharing and interaction trends among YouTube users regarding Invisalign treatment. The use of qualitative research in health care enables an in-depth understanding of patients’ thoughts and experiences . Since tLike in most studies on consumer health YouTube videos , the firThere is an intense activity on YouTube on obtaining information regarding treatment with Invisalign aligners.The emotional loading of viewers’ comments about Invisalign aligners was significantly more positive and was significantly associated with their status, content, and sponsorship of videos.Range of information, video duration, and time since upload did not significantly influence engagement and view metrics, a finding that warns against the unpredictable viewing preferences of YouTube users, and the incomplete information in popular Invisalign patient testimonials.


The increasing trend of mass shootings, which were associated with excessive use of violent video games, fueled the debate of possible effects violent video games may have on adolescents and young adults. The aim of this study was to investigate the possible link between violent video gaming effects and the disposition of adverse behavior traits such as interpersonal-affective deficits and disinhibition. Data of 167 young adults, collected by an online questionnaire battery, were analyzed for lifetime video game exposure differences  as well as for recent exposure effects on adverse behavior traits , while controlling for other potentially confounding lifestyle factors. While interpersonal-affective deficits were significantly higher in participants with ongoing violent video game exposure compared to non-gamers and non-violent video gamers, disinhibition was significantly higher in both – stopped and ongoing – violent video game exposure groups compared to non-gamers. Recent violent video game exposure was a stronger predictor for interpersonal-affective deficits, but was also significant for disinhibition. Considering that we observed small to medium effects in a sample of young adults with little to moderate use of violent video games highlights the importance of further investigating the potential adverse effects of violent video games on quality of social relationships. Video game exposure in adolescents aged between 8 and 18 years has been estimated to be around 15 h per week in the United States, with boys playing more than girls . FurtherThe concerns about potential adverse effects of video games can predominantly be attributed to violent video games. Even though numerous studies support the claim that violent video games affect adolescents’ attitudes and behaviors negatively , there aApart from an overall relationship between gaming and negative behavior, research suggests a link between violent video game exposure and isolated behavioral traits and behaviors, such as empathy, morality, and aggression. The analysis of longitudinal, experimental and cross-sectional studies suggests that there is a negative relationship between violent video gaming and empathy . Moreoveinterpersonal-affective deficits including social efficacy, pathological lying, and manipulative behavior and disinhibition including lack of impulse control, lack of planning, irresponsibility, and immediate reward seeking  and missing data on the items regarding gender (n = 3), mental health (n = 6), and drug use in the past 2 weeks (n = 6). Hence, data of 167 individuals was included in the analysis. Considering the video gaming behavior in this sample, four main groups were identified, namely non-video game users , non-violent video game users , video-game users who stopped playing violent games more than 2 months ago , and violent video game users . These groups were formed according to self-reported exposure to video games in the past. Participants themselves indicated whether they used violent or non-violent games. This distinction was furthermore tested by having experts rating the most commonly named games on the content of violence. Lastly, it is noteworthy that not only first-person shooter games were labeled as violent, but also strategy games which include virtual violence.The data from a total of 203 participants was collected using an online-questionnaire battery shared via social media. Inclusion criteria included: age between 16 and 24 years and good knowledge of the English language. Several participants had to be excluded due to age inclusion criteria  and aged between 19 and 21 years (70%). Furthermore, 90% of the sample was enrolled at a university [mostly at University College Roosevelt (UCR) – an honor’s college of Utrecht University located in the South West of Netherlands]. The remaining participants either studied at a lower level of higher education or were still at high school. Participants were fairly evenly distributed over a variety of educational fields. An overview of demographics, video game behavior, and psychopathic trait expression as well as lifestyle factors for all four groups can be found below in Limesurvey was used to collect the data online. The questionnaire, presented in English language, contained six subsections each collecting distinct information  necessary for this study. In total, this questionnaire required approximately 15–20 min for completion.The survey software The first section was concerned with the participant’s gender, age, and educational level . Multiple choice questions were used to ask for gender and age, whereas text boxes were provided for answers regarding educational level and field of study in order to avoid restricting answer possibilities.Limesurvey or have been designed to tap into information specific for this study.The second part (6 items) of the questionnaire retrieved information about the individual’s gaming behavior. Questions concerning duration  and intensity  of video game use as well as recent video game exposure within the past week  were either adapted from a previous studies, templates available on Youth Risk Behavior Survey . Participants were told that the aim of this study was to investigate the possible relationship between certain lifestyle factors and personal attitudes or beliefs toward the self and others. This study was approved by the internal ethics committee of the University College Roosevelt. Before starting the questionnaire, all participants gave informed consent. They were informed that they could stop answering questions at any point without any justification.1 differed among the various video game use groups when controlling for possible confounding effects including gender, age, educational level, drug use, psychological problems, physical exercise, and violent movie exposure. Due to violating the assumption of independence between covariates and group effects, violent movie exposure, and duration of videogame exposure in years were not included in the main analysis as common underlying mechanism can be expected between these covariates and the VG group factor. Multiple ANCOVA analyses were used instead of a MANCOVA because of the explorative nature of this analysis and the violation of multivariate normality  to violent video gaming and trait expressions, three multiple regression models with interpersonal-affective deficits, disinhibition, and the total collections of traits as dependent variables, were built. After adding the video gaming variables in the first two blocks, the other potential confounding variables were added in additional blocks to see how the relationship changed for violent video game exposure and psychopathic traits when controlling for these factors. Non-violent video game exposure was entered prior to violent video game exposure to investigate whether there is an added and distinct influence of recent violent video game exposure in particular.Table 2 summarizes the meaningful differences found in the psychopathy-related trait scores for the different video game exposure groups and other potential confounders.Possible connections to long-term video game use and trait expression were tested by multiple ANCOVAs. mean difference|≥ 3.33, all |p|≤ 0.01) mainly leading to the violation of the aforementioned assumption. To check whether duration of video game exposure explains a substantial part of variance in trait expression, a separate analysis was run with years of video game exposure as group variable  instead of the video game type groups. In this additional analysis, duration of video game use was not a significant factor for interpersonal-affective deficits . However, for disinhibition  and overall trait expression , the duration of video game exposure was a significant factor. Post hoc analyses of these effects indicated that only participants, who have never been exposed to video games, scored significantly lower , whereas there were no differences in medium to long-term exposure groups . Therefore, the observed effect may not necessarily be explained by varying degrees of exposure duration, but more likely by the previous use or non-use of video games, which was already conceptualized in the video game groups in the main analyses below.Due to the violation of the assumption regarding independence of covariate and treatment effects, the total years of exposure to video games was not included in the analysis presented below. There was a significant difference in years of exposure between the NVG group and all video gaming groups  = 7.07, p < 0.01, r = 0.50. All remaining covariates did not have a meaningful relationship with the overall trait expression .To begin with, a potential effect of video gaming behavior on the overall trait expression score was investigated. The only covariate, which turned out to be significantly related to the total trait expression score, was smoking, F = 3.95, p = 0.01, 2partial η = 0.07. When examining the differences between the individual video gaming groups via planned simple contrasts, there was no significant difference between NVG and NVVG, t(154) = 1.40, p = 0.16, r = 0.11. However, a significant increase in the total trait expression from NVG to SVVG exposure, t(154) = 2.73, p < 0.01, r = 0.22, and to VVG exposure, t(154) = 3.18, p < 0.01, r = 0.25, was detected. The means plot in Figure 1 shows the trend of the overall trait expression means across the different groups when controlling for possible confounding variables. Even though total trait scores are significantly higher in groups which have been exposed to violent video games in the past, it is important to point out that the trait expression is still on a lower to midrange level .A significant overall effect on total trait expression was found for the video gaming groups, F = 4.53, p = 0.04, r = 0.17, turned out significant. The positive correlation  suggests that increased alcohol use is therefore linked to a higher interpersonal-affective deficits score. All other covariates remained insignificant .When examining the association between video game use with interpersonal-affective deficits specifically while controlling for potential confounders, only the covariate alcohol consumption over the past months, F = 3.12, p = 0.03, 2partial η = 0.06. Planned contrasts were used to determine differences between groups. There was no distinction between NVG exposure and NVVG exposure, t(154) = 0.44, p = 0.67, r = 0.04. The differences between NVG exposure and SVVG exposure more than 2 months ago, however, just failed to reach significance, t(154) = 1.96, p = 0.05, r = 0.16. The comparison between no exposure vs. ongoing violent video game exposure, on the other hand, surpassed the statistical threshold indicating greater interpersonal-affective deficits in the VVG group compared to NVG participants, t(154) = 2.71, p = 0.01, r = 0.21. The trend of interpersonal-affective deficit scores across these different groups can be viewed in Figure 2. Yet again, even the highest means are in the lower to midrange level of trait expression scores.There was also a significant effect of video gaming behavior, while controlling for potential confounders, on interpersonal-affective deficits, r = 0.23, p < 0.01) to disinhibition scores, F = 4.41, p = 0.04, r = 0.34, and so was smoking , F = 13.21, p < 0.01, r = 0.73. Alcohol consumption, on the other hand, was negatively associated  with disinhibition scores, F = 5.04, p = 0.03, r = 0.38. This indicates that higher levels of perceived stress and smoking are related to more problems in cognitive control/disinhibition, whereas more frequent alcohol consumption was linked to less disinhibition in this student sample. Notably, the negative correlation with alcohol consumption is very small and insignificant. All the other covariates were insignificant .In this statistical analysis, several covariates were significantly related to disinhibition scores. First, stress was positively related  = 3.26, p = 0.02, 2partial η = 0.06. Planned simple contrasts with the non-gamers as reference group revealed that exposure to any video games was significantly related to higher disinhibition traits, as there was a meaningful difference to the NVG group, t(154) = 2.47, p = 0.02, r = 0.20, the SVVG group, t(154) = 2.78, p < 0.01, r = 0.22, and VVG group, t(154) = 2.46, p = 0.02, r = 0.19. Figure 3 displays the trend of secondary psychopathy scores across the different video game groups when controlling for the covariates.When controlling for all possible confounders, video gaming still had a significant effect on the disinhibition score, r), which range from 0.19 to 0.22.Even though mean scores are significantly higher, all means remain in the range of low to medium levels of secondary psychopathy. This is also reflected by the rather small effect sizes  of violent video game exposure with the different psychopathic trait domains. Before examining the trait sub-scores separately, it is interesting to analyze whether short-term exposure to violent video games is linked to the overall trait expression score.R2 = 0.22, F = 3.30, p < 0.01). The addition of violent video game exposure to the first block led to a significant improvement in model fit  and indicates that violent video game exposure explains about 7% of the variance in overall trait expression scores. The inclusion of gender, age, and educational level failed to significantly improved the model . Nevertheless, the last block led to a significantly better model fit .Overall, the final model explains 22% of the variance in total scores (p < 0.01), violent movie exposure  and smoking  were significant predictors of total trait expression. The B-values indicate that for each unit of smoking [range: 0 (none)–6 (every day)] an increase of 1.3 points on the overall trait scale is expected. For violent movie exposure a rise of about 2.5 points is predicted for each unit increase – amounting to a total difference of 10 points (about 9.6%) between no recent exposure and more than 7 times per week. Furthermore, the B-value of 3.49 in the final model indicates that increasing one level in violent video game exposure leads to an increase of approximately 3.5 points on the overall trait scale. This amounts to an increase of 16.8% (17.5 points) from no exposure in the past week to 10 or more hours of violent video game exposure.In the final model, violent video game exposure  = 3.27, p = 0.07] resulted in a significant improvement of the model fit . However, also the addition of the demographic variables in the third model  and the inclusion of other factors, which may confound the violent video game relationship to interpersonal-affective traits improved the model fit significantly . The final model in Table 3 explains approximately 25% of the variance in the interpersonal-affective trait scores .The addition of violent video game exposure to the first model . The video game exposure predictors were not significant in explaining the variation of disinhibition scores, as they only predict 1% of the variance . Furthermore, the demographic variables gender, age, and education did also not improve the model fit significantly . However, adding the last block with the remaining predictors, such as violent movie exposure, stress, physical exercise and drug use, did significantly improve the model fit  and accounts for almost all of the explained variance.The final model for disinhibition traits has a worse model fit than the interpersonal-affective traits model, as it only explains 16% of the variance , a decrease of 0.6 points would be expected. The effect size of violent video game exposure during the past week increased from the second model  to the final model . Therefore, violent video game exposure significantly predicts higher disinhibition scores . The B-value of 1.00 suggests that a difference in exposure from none to > 10 h in the last week leads to an increase of 12.5% (5 points) on the disinhibition scale. Non-violent video gaming , on the other hand, does not predict disinhibition scores.In the final model, only stress , whereas life-time exposure duration did not turn significant . For disinhibition, however, recent violent video game exposure turned insignificant , while the added life-time exposure was a significant predictor for relatively higher disinhibition scores .Lastly, an attempt to disentangle long-term and recent VG exposure was made by adding years of video game exposure to the regressions described above. However, these results have to be viewed with extra caution as due to the non-gamers these factors share substantial common variance with each other. Interestingly, for the interpersonal-affective deficits and overall trait score, recent violent video game exposure remained a significant predictor  video game exposure. Planned simple contrasts revealed that especially ongoing violent video game exposure was associated with significantly higher interpersonal-affective deficits as well as with increased disinhibition scores. Even though the effect sizes for these simple contrasts tended to be mostly small, these findings are congruent with previous studies investigating the link of violent video gaming with specific traits such as lack of empathy , impaireFor the overall collection of traits and more specifically for the disinhibition score, a significant difference was found between SVVG and no video game use. For the overall score and the interpersonal-affective deficit score, the effect sizes for the difference with the stopped violent video game exposure were smaller than for the ongoing exposure comparison. These findings may point toward the notion that effects of violent video games fade out after stopped exposure , and thaWhen looking at the intensity of violent video game exposure over the past week specifically, the findings were consistent with previous studies indicating that males tend to have higher adverse trait scores than females  and thatEven though the predictive power of the intensity of violent video game exposure was not as high as for the other adverse traits, it was also a significant predictor for disinhibition traits, considering that with increased exposure a higher disinhibition score was expected. This finding is congruent with previous studies which linked violent video gaming to increased aggressiveness ; as disiThe notion by Even though this empirical study has multiple strengths such as a relatively large sample, validated measures for the main constructs and elaborate statistical testing including assumption testing, there are also several limitations that have to be mentioned.First, convenience sampling was used to collect the data. The sample consisted predominantly (65%) of female participants. As this percentage deviates from the percentage of female gamers, gender was added as a covariate in our analysis. This showed that gender explained about 6.5 % of the variance in all adverse behavior traits. The high percentage of female students is representative of the populations of many college populations but may not represent the population of gamers very well. Therefore, the external validity of the findings is limited. It is interesting to note, however, that the number of female gamers is rising . ExpandiFurthermore, another drawback of the study is that participants’ exposure did vary among but also within video-game exposure groups. Therefore, the participants within a group (with video game use) may not be homogenous regarding the intensity of exposure they experienced. Additionally, there might also be a between group difference in intensity of video game exposure. More specifically, participants who use violent video games tend to spend more time with video gaming than participants of the other video game exposure groups. Therefore, it is unclear which influence the varying frequency of exposure had on the present findings. In future studies, a more stringent control for exposure frequency is needed. When considering the exposure frequency, especially in the prior week of recording, of all video game groups, the degree of exposure seems to be rather low  or physiological parameters , are recorded. The combination of subjective and physiological measures could then help to provide a better and possibly more complete measure of adverse behavior traits. For future cross-sectional studies, an introduction of four groups  may be useful to disentangle short-term effects from possible long-term exposure consequences on adverse behavior traits. Furthermore, future studies should also be able to provide more information about the directionality of the effects between violent video game exposure and adverse behavior traits. Here a well-controlled longitudinal study implementing objective and subjective measures of adverse behavior traits as well as an objective measure  recording the time spent on (violent) video games before first time exposure to such games would be most promising.Overall, there seems to be a link between self-reported violent video game exposure and differences in psychopathic trait expression – especially in interpersonal-affective deficits. Even though disinhibition problems were also found to be increased in (violent) video game groups, other stress-related factors seemed to have a higher predictive power than violent video game exposure. It might be unlikely that generally unburdened violent video gamers turn into real-life mass-shooters as often suggested by the public media, but violent video game exposure might in fact impact interpersonal-affective competencies in such a way that social interaction/contacts and relationships may be negatively affected. Therefore, considering the increasing and extensive use of violent video games, it is of utmost importance to continue pursuing the investigation of the potential impact of violent video games on their consumers’ personality traits as well as expressed behaviors.This study was carried out in accordance with the recommendations of the internal ethics committee of UCR (University College Roosevelt) with informed consent from all subjects. All subjects gave informed consent in accordance with the Declaration of Helsinki. The protocol was approved by the internal ethics committee of UCR. Since this study only included an online questionnaire no written informed consent was obtained. However, all participants were instructed that they should only proceed with the questionnaire, if they feel sufficiently informed and agree with the information given. Furthermore, they were informed that they could anytime withdraw from the study and that their participation is anonymous.A-CSK designed the online-questionnaire battery and collected the data, carried out the statistical analyses, wrote the initial draft of the manuscript, and reviewed/revised the manuscript thereafter. GA contributed to the design of the study, supervised the study’s development and data acquisition, and reviewed and edited the manuscript. BD provided the advice for the data analysis, contributed to/supervised the writing of the manuscript, and reviewed and edited the manuscript.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


This work aims to use functional 31P MRS‐MT to investigate the change in cerebral adenosine triphosphate (ATP) metabolic rates in healthy adults upon repeated visual stimuli.In vivo 31P MT experiments at 3 T.A magnetization saturation transfer sequence with narrowband selective saturation of γ‐ATP was developed for 1 relaxation times of phosphocreatine (PCr) and inorganic phosphate (Pi) at 3 T were measured to be 5.1 ± 0.8 s and 3.0 ± 1.4 s, respectively. Using steady‐state saturation of γ‐ATP, a significant 24% ± 14% and 11% ± 7% increase in the forward creatine kinase (CK) pseudo‐first‐order reaction rate constant, k1, was observed upon visual stimulation in the first and second cycles, respectively, of a paradigm consisting of 10‐minute rest followed by 10‐minute stimulation, with the measured baseline k1 being 0.35 ± 0.04 s−1. No significant changes in forward ATP synthase reaction rate, PCr/γ‐ATP, Pi/γ‐ATP, and nicotinamide adenine dinucleotide/γ‐ATP ratios, or intracellular pH were detected upon stimulation.Using progressive saturation of γ‐ATP, the intrinsic T31P MRS‐MT to determine the change in the forward CK reaction rate at 3 T. Magn Reson Med 79:22–30, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.This work demonstrates the potential of studying cerebral bioenergetics using functional  Based on this model, the 31P MRS‐observable changes in the PCr, ATP, and Pi magnetizations  with saturation time (tsat) can be described by the modified Bloch equations MATP=0 at all saturation times), these equations can be simplified to:T1,PCrint, T1,Piint are the intrinsic longitudinal relaxation times of PCr and Pi, respectively, corresponding to the relaxation rate in the absence of any exchange. In the steady‐state condition, with complete saturation of γ‐ATP, the Bloch equations can be further simplified with the boundary conditions of dMPCrdt=0 and dMPidt=0 to give: MPCr∞ and  MPi∞ are the steady‐state magnetizations of PCr and Pi. Previous animal and human studies have shown that the intrinsic T1s of PCr and Pi are insensitive to changes in physiology 1s of PCr and Pi in the human brain at 3 T. Therefore, in this study, T1,PCrint and T1,Piint values were measured at rest and were then assumed to be unchanged during activation.Cerebral ATP metabolic rates and fluxes can be measured in vivo using 1‐insensitive train to obliterate signal) saturation consisting of adiabatic hyperbolic secant pulses with variable amplitudes, has been used for frequency‐selective saturation The chemical shift between PCr and γ‐ATP is only ∼2.5 ppm, which means that it is difficult to saturate γ‐ATP without partially suppressing the PCr peak 31P spectra from the human brain with no saturation contain a broad, intense phospholipid baseline due to the chemical shift anisotropy of phospholipids, whose resonant frequency depends on their orientation in the field 31P spectra with and without saturation. To compensate for this, the baseline in the 31P spectrum with no MT saturation is normally removed before quantification using a cubic spline or Gaussian fit, or by removing the first few points of data in the time domain 31P spectrum with no peaks of interest. Because the rotation of the phospholipids is fast compared to the saturation time, phospholipid nuclei that contribute to the broad baseline pass through the orientation corresponding to saturation frequency at some point, and are thus saturated Conventional in vivo 31P MRS‐MT. First, the performance of the highly selective saturation sequence for γ‐ATP irradiation and baseline suppression was assessed. Second, longitudinal relaxation times (T1) of PCr and Pi at 3 T were determined using the progressive saturation of γ‐ATP. Finally, using the steady‐state saturation of γ‐ATP, the pseudo‐forward rate constants of CK and ATPase reactions (k1 and k2), concentrations of PCr and Pi, and intracellular pH (pHi) were quantified during alternating rest and visual stimulation periods.The principal aim of this study was to measure the changes in ATP metabolic rates in response to repeated, prolonged visual stimulation using 31P transmit–receive 14‐cm diameter loop coil (P‐140). A 1H image localizer was acquired at the start of each experiment, and the 31P coil was tuned and matched before 31P MRS acquisition. Shimming was performed using the Philips pencil beam method, which is based on the FASTMAP method This study was approved by the medical school ethics committee of the University of Nottingham, and each subject gave informed consent. The study was performed on a 3T Philips Achieva system  using a 31P MRS experiments. Prior to the ISIS localization sequence, a highly selective MT sequence was applied comprising multiple amplitude modulated pulses with a hyperbolic secant amplitude envelope (fixed maximum B1 of 2.06 μT and pulse duration of 114.29 ms), each having a narrow saturation band , interleaved with crusher gradients  along all three directions . The MT pulse was chosen to provide a saturation profile with a bandwidth that was narrow but sufficient to fully irradiate the γ‐ATP resonance, to have negligible sidebands and to limit energy deposition to allow the use of the pulse train with the ISIS localization sequence. The length of the saturation sequence could be adjusted by varying the number of pulses (np) and pulse gap (τ). The off‐resonance saturation was applied at either −2.5 ppm (relative to the PCr resonance at 0 ppm) to irradiate the γ‐ATP resonance  or at 15 ppm to suppress the phospholipid baseline alone.Figure 31P spectra with saturation applied at −2.5 ppm (γ‐ATP resonance), + 2.5 ppm, and +15 ppm, respectively, were acquired . Assuming that saturation at ±2.5 ppm leads to the same saturation on the PCr peak, then the comparison of the effect of saturation at +2.5 ppm and +15 ppm of the PCr peak should reveal any direct saturation due to RF bleed‐over (rather than magnetization transfer). Furthermore, comparison of the 31P spectra acquired with saturation at −2.5 ppm and +15 ppm should demonstrate if similar suppression of the phospholipid baseline was achieved.To assess the performance of this MT‐ISIS sequence, 31P spectra were acquired at resting state from a localized volume (5 × 9 × 7 cm3) chosen to cover the occipital lobe using the MT‐ISIS sequence  = 24, phase cycles = 8, scan time = 5 minutes). Seven 31P spectra were obtained at varying MT saturation times  using a varying number of saturation pulses  at a fixed pulse gap, τ of 50 ms.Six subjects  were recruited to participate in the γ‐ATP progressive saturation experiment. MPCr0 and MPi0), with the broad baseline attenuated by applying a train of 32 pulses off‐resonance at + 15 ppm. The remaining six γ‐ATP saturation scans were acquired in a random order. The total scan time was approximately 45 minutes. The intrinsic T1 of PCr and Pi were determined by fitting MPCr  and MPi measured for different values of tsat in this progressive γ‐ATP saturation experiment, to Eq. [1].The first scan had no saturation at the γ‐ATP resonance yielding the Boltzmann equilibrium PCr and Pi magnetizations  undertook a visual stimulus paradigm which applied two cycles of a 10‐minute rest block followed by a 10‐minute visual stimulation block. The visual stimulation comprised contrast‐defined wedges moving toward or away from a fixation cross of randomized color 31P spectra (NA = 24) were acquired: one without MT saturation at the γ‐ATP resonance (tsat = 0 s) to measure Boltzmann equilibrium magnetizations , and one with sufficiently long MT saturation time (tsat = 9820 ms) to measure steady‐state magnetization . The total scan time of this session was approximately 50 minutes. The forward rate constants of CK and ATPase reactions (k1 and k2) were calculated based on Eq. [2].During each block, two 31P data were analyzed in jMRUI version 4 (http://www.jmrui.eu/) 31P metabolites was performed with the AMARES  algorithm 31P spectra were fitted to 12 individual components for 10 metabolite resonances belonging to phosphoethanolamine, phosphocholine, intracellular Pi, glycerophosphoethanolamine, glycerophosphocholine, membrane phospholipids, PCr, γ‐ATP, α‐ATP, and NAD(H). The doublets of γ‐ATP (−2.5 ppm) and α‐ATP (−7.5 ppm) were both fitted as two peak components with fixed separation of 16 Hz (J‐coupling constant) The 1 of PCr and Pi. The goodness of fit was assessed from the coefficient of determination, R2. The forward rate constants of CK and ATPase reactions were calculated from Eq. [2] based on the PCr and Pi signals  measured in the steady‐state γ‐ATP saturation experiment. For each block in the visual stimulation paradigm, the concentrations of PCr ([PCr] = (SPCr/γ‐ATP)S × [ATP]) and Pi ([Pi] = (SPi/γ‐ATP)S × [ATP]) were calculated based on the fully relaxed signals from the 31P spectra in the absence of γ‐ATP saturation (TR = 12 s), assuming the relatively stable ATP concentration in the human brain to be 3 mM FfCK = k1 × [PCr] and FfATPase2 = k × [Pi], and converted into units of μmol/g/min, assuming a brain tissue density of 1.1 g/mL i values for each block were determined based on the chemical shift difference (δPCr−Pi) between the PCr and intracellular Pi signals t‐tests were performed to test for significant differences in forward reaction rate constants, metabolite concentrations, and pHi between stimulation and rest blocks.Next, the quantified signals (peak areas) of PCr and Pi from the γ‐ATP progressive saturation experiment were least squares fitted to the model in Eq. [1] using MATLAB  to estimate the intrinsic TT1int) via the progressive saturation of γ‐ATP, a Monte Carlo (MC) simulation study was performed, based on the time courses of PCr and Pi signals simulated using the model given in Eq. [1], and the assumed T1int s and forward reaction rates  [2]. Random normally distributed noise of similar variance as found in the in vivo T1 measurements was added to the simulated signal curves, producing 1000 datasets, which were then individually least squares fitted, to predict the average uncertainty (standard deviation) and mean value of the estimated T1int of PCr and Pi.To assess the error in the estimate of the intrinsic longitudinal relaxation time  via the steady‐state saturation of γ‐ATP. For different assumed relative errors in T1int , and simulated signals of PCr and Pi (Eq. [1]) at two saturation times (tsat = 0 and 10 s) with added noise (1000 datasets), k1 and k2 were calculated using Eq. [2], and the coefficients of variation of the estimated values were determined.A second MC simulation was performed to assess the effect of this uncertainty in the estimated 31P spectra acquired were of excellent spectral quality across all subjects .Figure tsat). The Pi signal decreased more slowly and to a lesser extent with increasing tsat, due to the slower ATPase reaction rate compared to the CK reaction rate [3] and the lower concentration of Pi compared to PCr. Figure T1int) at 3 T were measured to be 5.1 ± 0.8 s for PCr (R2 = 0.99) and 3.0 ± 1.4 s for Pi (R2 = 0.7). The uncertainties in the estimated intrinsic T1 values were determined from the MC simulation  during the functional MRS (fMRS) experiment was determined for each block, and found to be 0.35 ± 0.04 s−1 , 0.43 ± 0.02 s−1 , 0.37 ± 0.03 s−1 , and 0.41 ± 0.04 s−1 . Figure k1, between stimulus states was quite consistent across subjects. On average, a 24% ± 14% increase in k1 from baseline was observed during the first visual stimulation ON block (P = 2 × 10−4). There was no significant change in k1 between the first and second rest (OFF) blocks (P = 0.36), indicating that k1 returned to baseline level during the second rest block after visual stimulation. In addition, an 11% ± 7% increase was observed during the second visual stimulation block (P = 0.001). There was no significant difference in k1 between the first and second visual stimulation (P = 0.08), with k1 elevated by 18% ± 12% when averaged over both visual stimulation periods (P = 2 × 10−6). The forward exchange fluxes for the CK reaction (FfCK = k1 × [PCr]) were found to increase from 1.32 ± 0.15 mM/s (or 72.2 ± 8.2 μmol/g/min) at rest to 1.56 ± 0.11 mM/s (or 85.5 ± 6.0 μmol/g/min) on visual stimulation (an 18% increase).Using the estimated T1int of Pi, the forward rate constant of the ATPase reaction (k2) in each simulation block was found to be 0.15 ± 0.05 s−1 (stim‐OFF), 0.18 ± 0.09 s−1 (stim‐ON), 0.15 ± 0.08 s−1 (stim‐OFF), and 0.17 ± 0.10 s−1 (stim‐ON). The relative change in k2 showed a similar pattern across blocks to k1 , and between the second OFF and ON blocks of 12% (P = 0.72). Results from the MC simulation (Table k1 (CVk1% ≈ 7%) is smaller than for k2 (CVk2% ≈ 23%), largely independent of the relative errors in the estimated intrinsic T1. This indicates that a change less than 7% in k1 or 23% in k2 is unlikely to be detected. The baseline forward exchange flux for the ATPase reaction (FfATPase = k2 × [Pi]) was determined to be 2.4 ± 0.8 mM/s (or 13.2 ± 4.4 μmol/g/min).Using the estimated action k in each i measured in each block. The concentration of PCr was found to be 3.7 ± 0.3 mM, with no significant difference between rest and visual stimulation (P = 0.48), indicating that the activation‐induced change found in FfCK was entirely due to the change in k1. In addition, the concentration of Pi was determined to be 1.6 ± 0.1 mM, with no significant difference between rest and visual stimulation (P = 0.99). There was no significant difference observed in the average pHi at rest and on visual stimulation . Lastly, the tendency for a decrease in NAD(H)/γ‐ATP ratio upon the first visual stimulation block was not statistically significant .Table max = 3 W/kg) compared to 30 s or longer required by a conventional BISTRO saturation sequence with ISIS 31P spectra, and therefore produce a more consistent baseline across acquisitions with and without MT saturation at the γ‐ATP resonance.The magnetization saturation transfer sequence used in this study was designed to provide high frequency‐selectivity for effective saturation of γ‐ATP while keeping the RF power deposition low enough to allow it to be used with ISIS localization with a reasonable TR. This enabled the use of a TR of 12 s  was obtained at 3 T in this study, which can be compared to 4.9 ± 0.5 s measured in the human brain at 7 T [2] and 3.8 ± 0.6 s in the rat brain at 9.4 T [4]. The decrease in T1,PCrint with the increasing B0 field strength suggests that the relaxation of 31P spins in PCr is dominated by the chemical shift anisotropy mechanism T1,Piint measured at 3 T in this study (3.0 ± 1.4 s) was shorter than the values of 3.6 ± 0.7 s, 3.8 ± 0.4 s, and 4.0 ± 0.6 s reported at 4 T, 7 T and 9.4 T 31P spins in Pi may be dominated by dipolar interactions.A measurement of n at 7 T  and 3.8 k1) measured using the steady‐state saturation of γ‐ATP (0.35 ± 0.04 s−1), is consistent with k1 at resting state obtained from the progressive saturation experiment (0.37 ± 0.07 s−1). Early 31P studies reported k1 values of 0.3 ± 0.04 s−1 and 0.16 ± 0.02 s−1 in the human brain regions of predominantly gray matter and white matter, respectively −1 over the entire human brain k1 values are more comparable with the more recently reported values of 0.33 ± 0.04 s−1 [2] and 0.32 ± 0.08 s−1k2) at rest obtained in this study from the steady‐state and progressive MT experiments  are comparable with each other, and with the previously reported values of 0.17 ± 0.04 s−1 [3], 0.18 ± 0.05 s−1 [2], and 0.21 ± 0.04 s−1The baseline forward rate constant of the CK reaction (2) utilization (CMRO2 = 1.71 ± 0.18 μmol/g/min) in the human occipital lobe 2 ratio of 6 [4]. Our estimate for the forward exchange flux for the ATPase reaction, FfATPase = 13.2 ± 4.4 μmol/g/min, derived from the 31P steady‐state MT measurement of k2 and [Pi] at rest (baseline), is in good agreement with this, as well as values reported in previous 31P MT studies (12.1 ± 2.8 μmol/g/min [3] and 8.8 ± 1.9 μmol/g/min [2]), which did not use a localization sequence, but relied on the spatial selectivity of the surface coils used. This suggests that the forward exchange flux of the ATPase reaction measured by the 31P MT method reflects the net oxidative ATP phosphorylation rate in the human brain. The possible reasons for this are discussed at length in Lei et al. The cerebral ATP synthesis flux through oxidative phosphorylation estimated from PET measurements of the cerebral metabolic rate of oxygen  visual stimulation In this study, increases of 24% ± 14% and 11% ± 7% in the pseudo‐forward rate constant of the CK reaction, 31P MRS studies in animal k1) during stimulation can be possibly explained by a slightly elevated ADP concentration 1H MRS studies at 7 T The baseline PCr/γ‐ATP ratio obtained in this study was 1.22 ± 0.09 (at rest), which is comparable to the previously reported value of 1.3 ± 0.1 measured from the human occipital lobe [2]. In addition, despite the possibility of quantification error due to the limited SNR of the Pi resonance, the baseline concentration of Pi ([Pi] = 1.6 ± 0.1 mM) measured is within the range of previously reported values 0.85–1.7 mM)  mM 31P Mi was previously reported during photic stimulation i due to stimulation is age dependent, as the pHi increase found in a middle‐aged group (54.4 ± 10.5 years) was not observed in a younger group (28.9 ± 10.5 years). No significant change in pHi was detected in response to visual stimulation  in this study in young healthy volunteers. This agrees with other recent 31P human studies 31P MRS voxel i during the prolonged visual stimulation. Significant decreases of ∼5% and ∼2% in NAD(H)/ATP have been recently reported during short (1.5 minutes) and long (5 minutes) photic stimulations The pH change during brain functional activation is unclear tsat), would tend to cause an underestimation of k1 and k231P spectra acquired at the shortest tsat  were not much higher than the noise level (∼4%). Secondly, using a short TR could cause partial saturation of the acquired 31P signals, especially for scans with long tsat, which would then lead to an underestimation of k1 and k2 in the steady‐state saturation experiments. Based on a model that considers partial saturation [3], the partial saturation effect on M(tsat)/M0 when using a TR of 12 s (as in this study), was found to be small (∼3% for PCr and ∼1% for Pi at the longest tsat = 10 s). Thirdly, the 31P signals from Pi in the intracellular and extracellular compartments were not well resolved at 3 T (this study) or 4 T k2 based on the total Pi signal may therefore lead to the underestimation of k2. The fact that our measured pH (6.99 ± 0.04) was closer to the previously reported intracellular pH values of 7.06 k2 reported in this study are primarily determined by the dominant intracellular Pi signal. In future studies, the design of the 31P fMRS experiment could be improved by interleaving the two types of scan (tsat = 0 and 10 s), as this would enable an increase in the temporal resolution for the k1 and k2 measurements, thus potentially allowing the observation of progressive changes within each stimulation block (assuming that the SNR was sufficient).There are a few possible sources of error leading to potential bias in our results. Firstly, poor or incomplete saturation of γ‐ATP, especially at short saturation time (31P MRS‐MT techniques at 3 T for future noninvasive studies of bioenergetics in response to stimulation, and in a variety of neurological and neuropsychiatric disorders.This work has demonstrated the effectiveness of a highly selective saturation sequence for selective γ‐ATP irradiation and phospholipid baseline suppression. Our findings suggest that the forward creatine kinase reaction rate is sensitive to increased brain functional activity. Results show the feasibility of using


Assessment of the microcirculation is a promising target for the hemodynamic management of critically ill patients. However, just as the sole reliance on macrocirculatory parameters, single static parameters of the microcirculation may not represent a sufficient guide. Our hypothesis was that by serial topical application of acetylcholine (ACH) and nitroglycerin (NG), the sublingual microcirculation can be challenged to determine its endothelial cell-dependent and smooth muscle-dependent physiological reserve capacity.In 41 healthy subjects, sublingual capillary microscopy was performed before and after topical application of ACH and NG. Total vessel density (TVD) was assessed in parallel using manual computer-assisted image analysis as well as a fully automated analysis pathway utilizing a newly developed computer algorithm. Flow velocity was assessed using space-time diagrams of the venules as well as the algorithm-based calculation of an average perfused speed indicator (APSI).No change in all measured parameters was detected after sublingual topical application of ACH. Sublingual topical application of NG however led to an increase in TVD, space-time diagram-derived venular flow velocity and APSI. No difference was detected in heart rate, blood pressure, and cardiac output as measured by echocardiography, as well as in plasma nitric oxide metabolite content before and after the topical application of ACH and NG.In healthy subjects, the sublingual microcirculatory physiological reserve can be assessed non-invasively by topical application of nitroglycerin without affecting systemic circulation. The primary goal of hemodynamic management in critically ill patients in shock is to ensure adequate oxygen delivery to the tissue. Currently intervention protocols are mostly targeting global oxygen delivery by optimizing intravascular blood volume, vascular tone, cardiac output, and hematocrit –4, but tMultiple approaches for the assessment of the microcirculation have been suggested. These range from clinical parameters such as skin mottling , toe temThis study was approved by the Ethics Committee of the University of Bern  and conducted in accordance with the declaration of Helsinki.2) were included in the study. All were physically active but not involved in elite sport. All subjects underwent examination of the sublingual microcirculation by capillary microscopy before and after topical application of ACH and NG. According to a predetermined study time plan, clinical and echocardiography examinations as well as blood sampling were performed before the examination of the microcirculation in one group of subjects (n = 30), and less than 1 h afterwards in the remaining subjects (n = 11).Fourty-one healthy Caucasian persons  male, weight 69.0 ± 1.8 kg, height 174 ± 1 cm, BMI 23.1 ± 0.8 kg/m3-based chemiluminescent nitric oxide analyzer . The method is described in more detail elsewhere [Heart rate as well as systemic arterial blood pressure were obtained non-invasively using the oscillometric technique. Venous blood was sampled from an antecubital vein into heparinized containers and was immediately centrifuged and deep frozen on site. Plasma nitric oxide metabolite content was then measured following ethanol-induced protein precipitation and centrifugation using a vanadium(III) assay to reduce nitrate, S-nitrosothiol and nitrite to nitric oxide that was then detected in a helium driven, ozone/Ilsewhere . ArteriaEchocardiography examinations were performed using a portable device with tissue Doppler imaging capability . Stroke volume was measured by multiplying left ventricular outflow tract velocity time integral as recorded in the parasternal short axis by pulsed wave Doppler and left ventricular outflow tract area derived from its diameter. Cardiac output was obtained by multiplication of stroke volume and heart rate derived from the peak-to-peak distance of the outflow tract Doppler signal. All measurements were performed in triplicates and recorded digitally for offline assessment which was performed after removal of subject identifiable by a single operator. The means of the three respective measurements are reported.2. Each video clip was recorded at a length of 10 s. All examinations in this study were performed by a single operator with the subject in supine position and at rest. Four video clips of a random sublingual area were digitally recorded. Additionally, two video recordings were obtained after topical application of ACH and a futher two after topical application of NG in order to test endothelium-dependent and endothelium-independent physiological mirocirculatory reserve, respectively. All measured parameters are reported as the mean of obtained video clips in order to compensate for changes in microscope field of view in between measurements in compliance with the international consensus [−2 M) ACH solution immediately after reconstitution of ACH lyophilisate  using distilled water, yielding a dose of 0.5 mg (3.4 μmol) per application. Following the recording of the two ACH video sequences, NG was applied to the sublingual area to be analyzed as one drop (0.05 ml) of 1% (4.4·10−2 M) NG solution  diluted 1:102 with 0.9% sodium chloride, yielding 0.005 mg (2.2·10−2 μmol) per dose.High-resolution capillary microscopy was performed using the incident dark field (IDF) technique  with a Consensus ; howeverIn each of the 10-s video clips recorded a stable sequence of ≥150 frames, corresponding to 6 s, was identified. The resulting video clips were graded using Massey’s scoring system , and anaFor manual video analysis, the digital video files were converted to a format and resolution compatible with previous microscopy hardware and presented in a blinded fashion. TVD was measured using software-assisted manual vessel detection   in line 2. Thereafter, a “speed image” was calculated along the centerline of all detected capillaries using a Gaussian convolution kernel, yielding not an absolute measure of speed but rather a relative speed based on intensity variation, called the speed indicator. A spatial average of the speed indicator is reported as an index of the average microcirculatory flow velocity of all perfused vessels (average perfused speed indicator (APSI)).For automated video analysis, TVD was calculated from the video files using CytoCam Tools 1.7.12 , employing an automated vessel detection algorithm based on Frangi’s multiscale vessel enhancement filtering algorithm described in detail elsewhere . The algU test. Categorical population attributes were compared using Fisher’s exact test. For correlation of TVD between manual and algorithm-based video analysis, Pearson’s product-moment correlation coefficient and Bland-Altman analysis [p < 0.05 was considered statistically significant. For all statistical analysis, a fully scripted data management pathway was created within the R environment for statistical computing, version 3.3.0 [Comparisons of microcirculatory parameters before and after interventions were performed using one-way analysis of variance (ANOVA). Pairwise analysis was performed using pairwise two-sample tests with Benjamini and Hochberg’s correction algorithm  applied.analysis , 40 wereon 3.3.0 . Graphicon 3.3.0 . Values Heart rate, systemic arterial blood pressure, and cardiac output as measured by echocardiography were within the normal range and were similar whether measured before or after the sublingual application of ACH and NG Table . The gror = 0.42, p < 0.001), Bland-Altman analysis revealed a bias of 2.1 mm/mm2 and a precision of 4.8 mm/mm2. Representative still images of the microcirculation before and after the application of an ACH and NG challenge are shown in Fig. Three hundred twenty-eight video clips of the sublingual microcirculation were graded, 325 of which presented with a Massey score <10 and were provisioned to further analysis. The analyzed video clips were of good quality with a mean Massey score of 1.3 ± 0.1 . Venular anatomy favorable for the calculation of space-time diagram-based venular flow velocity was present in 23, 27, and 14 out of 41 subjects during the native, ACH, and NG condition, respectively. Manual computer-assisted video analysis revealed no influence of topical application of ACH to the sublingual mucosa on TVD or the blood flow velocity within the venules as quantified by space-time diagrams. Topical application of NG to the sublingual mucosa however led to an increase in TVD as well as space-time diagram-based flow velocity (Table Our study demonstrates that (I) nitroglycerin but not acetylcholine applied topically to the sublingual mucosa increases both total vessel density and local capillary flow velocity in healthy volunteers, (II) without causing measurable systemic effects. Thus, the topical sublingual application of nitroglycrine in combination with microcirculatory video microscopy provides a means to quantify the sublingual physiological microcirculatory reserve. In addition, we have employed manual computer-assisted video analysis as well as introduced an objective and reproducible algorithm for the analysis of capillary microscopy videos, (III) yielding moderately comparable results.Previous studies have demonstrated NG to increase sublingual microvascular flow velocity in septic shock after systemic application –45. The A previous study examining patients in cardiogenic shock has found that in a subgroup of ten patients, topical application of ACH to the sublingual mucosa led to an increase in the proportion of perfused capillaries, but no change in TVD . Later, During topical application of 0.5 mg of ACH and 0.005 mg of NG to the sublingual mucosa in the present study, systemic arterial blood pressure, heart rate, and cardiac output as well as hematological and metabolic status remained unchanged. This corresponds to previous data reporting effects limited to the area of application after intra-ocular injection of much higher doses (5–20 mg) of the ACH preparation used in this study, Miochol E . NG as uThe use of a nitroglycerin challenge to test physiological microcirculatory reserve allows the identification of the capillaries recruitable by maximal relaxation of the vascular smooth muscle cells; however, it cannot be ruled out that some unrecruited vessels remain. Further, the observation of the isolated effect of NG application is overlapped by the stepwise approach consisting of the stimulation of endogenous NO release by the application of ACH followed by the provision of excess exogenous NO by the application of NG as employed in the present study. Additionally, technical limitations regarding the assessment of the microcirculation in the present study include three main points. First, the use of a frame rate of 25 frames per second during video capture, potentially leading to the inability to identify individual erythrocytes under conditions of high flow velocity. Future hardware should aim at a higher frame rate of at least 60 frames per second in order to avoid aliasing effects in the determination of microcirculatory flow velocity when used in combination with stimulation tests such as the topical application of vasodilators. Second, only two video clips were recorded after the topical application of both ACH and NG in order to limit total examination time and minimize confounding factors such as changes in the macrocirculation over time. Nevertheless, three video clips should be recorded per measurement in future studies if the clips are not recorded at the exact same mucosal location in order to limit selection bias and fully comply with the international consensus . The impOur data demonstrates that in healthy subjects, the sublingual physiological microcirculatory reserve can be assessed non-invasively by topical application of nitroglycerin without affecting systemic circulation, through the mobilization of both the microcirculatory diffusion and convection reserve. Such measurements may be conducted in critically ill patients in a future study to test the microcirculatory response to resuscitation. It remains to be seen if stimulation with acetylcholine enables the differentiation of the physiological microcirculatory reserve into endothelium cell-dependent and smooth muscle-dependent fractions in subjects with altered microcirculation. Further, automated algorithm-based analysis has been found to reasonably approximate manual analysis of microcirculatory video for assessment of the physiological microcirculatory reserve.


Across social media platforms users (sub)consciously represent themselves in a way which is appropriate for their intended audience. This has unknown impacts on studies with unobtrusive designs based on digital  platforms, and studies of contemporary social phenomena in online settings. A lack of appropriate methods to identify, control for, and mitigate the effects of self-representation, the propensity to express socially responding characteristics or self-censorship in digital settings, hinders the ability of researchers to confidently interpret and generalize their findings. This article proposes applying boosted regression modelling to fill this research gap. A case study of paid Amazon Mechanical Turk workers (n = 509) is presented where workers completed psychometric surveys and provided anonymized access to their Facebook timelines. Our research finds indicators of self-representation on Facebook, facilitating suggestions for its mitigation. We validate the use of LIWC for Facebook personality studies, as well as find discrepancies with extant literature about the use of LIWC-only approaches in unobtrusive designs. Using survey data and LIWC sentiment categories as predictors, the boosted regression model classified the Five Factor personality model with an average accuracy of 74.6%. The contribution of this work is an accurate prediction of psychometric information based on short, informal text. Across platforms like Facebook, LinkedIn, Twitter, and blogging services, users (sub)consciously represent themselves in a way which is appropriate for their intended audience –5. HowevThis article has two aims:To explore the relationship between offline and online personalities via survey responses and self-produced text such that;Participant-influenced biases in publically sourced data can be mitigated.In response to these research aims, we hypothesize that self-representation can be identified by test-based attributes (Section 2) and describe a mechanism to do so in the context of Facebook studies. For this, we employed the popular crowdwork platform Amazon Mechanical Turk, receiving survey responses and anonymous Facebook Timeline data from 509 workers (Section 3). Following on from the identification of self-representation, we discuss how it can be controlled for in broad social models (Section 4). Section 5 then discusses the implications of this work and summarizes the contribution, limitations, and points out areas for future work (Section 6).Self-representation has been discussed in several works for online and offline fora. These studies discuss that one's tendency to truthfully disclose or censor personal information emanates from an associated intrinsic value –18. ManyWe define self-representation in accordance with Goffman  as contrSelf-representation is also bound to time and place. In real life one must immediately respond to an interlocutor or opponent. In social networks, one has the option not to act immediately. This is even true in the case of messaging platforms using delivered/read notifications . Even these types of sites deliver notifications of messages to the front page or screen of the interface, thus allowing the user to opt to respond at a time of their choice. Local binding is functionally eliminated with online social networks ,25. In rIndividuals self-represent due to an increase in intrinsic value ,25. AcroThere is still open debate on the extent of self-representation online. For example, online self-representation was challenged by , who finStudies show that honest self-disclosure is generally more emphasized in real life and is different online ,13,18. ,33. The Facebook’s study on self-disclosure, the typing then editing, deleting, or posting of statuses and comments from 3.9 million Facebook users, found that 71% of users self-censor in some way. Males censor more than female, and Facebook posts are more frequently regulated than comments. They find that those with higher boundaries (estimated by the amount of regulations on visibility in place for a given audience member of the posting person) self-censor more, and theorize that lack of control drives self-censorship. Given that perceived lack of control is a characteristic of neurotic personalities –40, actiThis section concentrates on the properties and related finding of the text analysis package Linguistic Inquiry and Word Count (LIWC). This review is not extensive, and does not cover the multiple non-LIWC tools available to measure computational affect, psychometrics, and sentiment analysis. LIWC’s premise is that it is function and not context of the word that matters. Latent emotional and psychological states are revealed by word function more than the words actually in use. Function words comprise approximately 55% of a given language and are difficult and expensive to manipulate . FunctioRecent criticisms of LIWC’s fundamental approach suggest two problems: LIWC has yet to be thoroughly validated for different mediums of online social media data ,30, and Two studies closely match the approach of this work and are elucidated here. The initial study applying LIWC to assess personality traits from online discourse is the work . YarkoniThe work  also conThis work differs on several aspects. We utilize regression modelling instead of correlations for our reporting as opposed to the Yarkoni work. However, our models are built to respect the high variable-to-predictor ratio, thus use boosted models  which is a difference in approach to the work of Schwartz and colleagues.We report word categories in the style of  rather tWe note that many studies exist in literature that are not analysed in depth here . TheGiven the status of the literature, an interesting question is raised on the unknown interaction between personality types, posting on Facebook, and propensity for self-representation. A link between online self-representation and real-life personality has neither been definitively addressed in cyberpsychology nor sentiment analytics literature ,47,64 onPersonality is good basis for the identification of self-representation due to its known relationships in on- and offline fora ,64,65 anH1 Self-representation is characterized by withdrawing or enhancing psychometric characteristics on Facebook.H1a Positivity bias (enhanced positivity and withdrawn negativity) is a characteristic of self-representation on Facebook.H1b Enhanced confidence is a characteristic of self-representation on Facebook.H2 Personality is detectable and is not mitigated via self-representation.H2a Online self-representation cannot distort digital traces of personality that they become undetectable.H2b LIWC features detect the attributes of personality on Facebook.https://doi.org/10.5281/zenodo.852652. To facilitate our study, 509 Amazon Mechanical Turk (AMT) workers completed psychometric surveys via a Facebook application. In use for personality is the Big Five Inventory introduced by , though those with a higher number of friends have a negative relationship with the frequency of logins  [SM 1/3]. A negative relationship also exists between number of Facebook friends and the number of updates  [SM 2/3].There are some generally interesting results dealing with self-reported contact patterns and motivation of use outside of self-representation issues revealed by the Spearman’s ρ and binomial regression analyses. Participants who use Facebook frequently also update their profiles frequently (rp = 0.071) [SM 9H/SM4]. Those who mainly like status updates are most likely to contact family members (Exp(B) = 2.320, p = 0.006) [SM 1D/SM4]. Participants who use Facebook in order to be recognized by others and are half as likely to have offline friends on Facebook as the rest of the population (Exp(B) = 0.550, p = 0.085), and are twice as likely to be interested in contacting family members on Facebook (Exp(B) = 1,989, p = 0,067) [SM 9C/4]. An exception here is those who want recognition and support from other users: they are half as likely to contact family members (Exp(B) = 0.406, p = 0.011) [SM 9E/4]. Men are less interested in maintaining contact with family on Facebook as women (Exp(B) = 0.393, p = 0.001) [SM4], and those who frequently like videos are twice as likely to use Facebook for contacting their family (Exp(B) = 2.502, p = 0.004) [SM5/4]. Participants whose profile picture does not show their face are half as likely to want to contact offline friends and are more interested in finding unknown online friends (Exp(B) = 0.413, p = 0.007) [SM 11F/4], as well as participants who agree with the statement ‘I can determine myself what I do or do not show others’ (Exp(B) = 1.344, p = 0.033) [SM14B/4].Family, and on and offline friends are major interest areas in this sample. Participants who use Facebook to show what they know and can are less interested in contacting family than all other groups  (Exp(B) = 0.5, As seen in The analysis also looked at expressed confidence as a measure of self-representation (H1b). This is measured by the frequency in usage of first person singular and third person plural; where people that are more confident use ‘I’ words less than ‘We’ words ,93. We ts(282) = .357 p < .0005] / [rs(282) = -.263 p < .0005]) that further analyses are precluded. We introduce these attributes as personality vectors  and also introduces models with only data that would be available from Facebook profiles (the LIWC categories) to define the relationships between LIWC and psychometrics Tables –6 H2b).b.s282) 2 s(282) Openness has the high prediction accuracy at 65.0%, and an explained variance of 47.2%. Significant at the 0.001 level for openness are the survey categories meaning [HF 4], self-esteem [HF 9], engagement [HF3], competence [HF 1], optimism [HF 5], positive emotion [HF 6], and resilience [HF 9]; the country of origin of the worker; and the LIWC category ‘feelings.’2 (explained variance) of 43.3%, conscientiousness is described by the largest collection of LIWC categories of all five traits  more than the other traits, which could be a display of withdrawn confidence as expressed online .Agreeableness has an accuracy of 63.5% and 46.3% explained variance indicating high reliability. Highly significant are the survey items resilience [HF 8], meaning [HF 4], self-esteem [HF 9], and competence [HF 1]; country of origin; the LIWC categories ‘friends’, ‘inhibition’, ‘feelings’, and ‘assent’; and declination of ‘I can be who or what I want on my Profile page’ [SM 14D]. Unexpectedly those scoring high on this trait reflect withdrawn usage of Positive Emotion . They sc2 (49.9%). The most significant survey items are resilience [HF 8], self-esteem [HF 9], emotional stability [HF 2], vitality [HF 10], and optimism [HF 5]; using Facebook to spy on others [SM 9D], managing presentation of self with pictures not of them [SM 11F], using Facebook to observe other people [SM 9F], and liking videos on Facebook [SM 5]. Finally, the LIWC category ‘feelings’ is highly significant. Neuroticism has a good performance (70.8% accuracy) and reasonable RWorker’s self-produced text is indicative of self-representation when compared to their responses to the Five Factor model (H2). The Automated Linear Modelling approach in SPSS creates meritorious model fits averaging 68.8% reference model accuracy and 48.6% explained variance as seen in p < .05).Considering sizeable correlations between predictor groups, the unique variance explained by each of the variables indexed by the squared semipartial correlations is low. In no case was there an instance of Cook’s Distance larger than one, so all outliers were handled within the data rather than trimmed . The mulWhen nested cross-validation is additionally performed we see an average result of 0.67 , Table 8Our models have three major differentiators with the works of ,48. FirsHaving established a compact representation of the five personality traits of  detectedThe key findings of this research are that self-representation in online social media is an identifiable phenomenon, that self-representation can be isolated, and a smaller number of indicators than previously reported can be used to do so. Moreover, it opens an interesting discussion on the impact of self-representation on social media analyses, both from the perspective of the researcher validating social models, and the subject with respect to the intent of such behaviours. To our knowledge this is the first work that validates Facebook applying LIWC as a stand-alone tool for the identification of personality traits and self-representation. Similar studies have validated other text inputs , or havSelf-representation was identified in a number of indicators. Positive affectivity and withdrawn negative emotions are identifiable across the workers’ profiles. Withdrawn negative affect is a particularly indicative of self-representation (H1a). However, confidence follows expected patterns across genders (H1b). Male participants appear more confident in their written profiles than females. As this is a finding in emergent literature, this cannot be understood as an overt measure of self-representation. Personality is still detectable even when self-representation is present (H2a), and LIWC-only features have meritorious performance in comparison to latent semantic methods like the open vocabulary approach of  (H2b). OThe stated aims of this research are twofold: establishing the relationship between offline and online personalities in order to mitigate such biases in publically sourced data. In accomplishing these goals, this research creates a generally applicable method for the design of cross-disciplinary methods and the analysis of social media data. Such a method is impactful in both research arenas and commercial domains, in that it allows the study designer to approximate participant baselines without highly intrusive mechanisms. A strength of this study is its consideration and application of the findings from recent cyberpsychology literature.In a systematic manner, this research detailed the experimental design, data collection, and analysis. Common method biases are addressed and appropriately eliminated when identified. The method allows for replication by careful detailing of the steps, (pre)processing of data and models built. A major contribution is addressing method biases in the harvesting and analysis of social media data. This research utilizes the entire data stream as posted by the individual per profile, mitigating sampling errors. It also names common markers of the phenomena of self-representation based on simple LIWC categories and psychometrics that allow researchers to mitigate its effects in future research. With personality and mood validated and a sentiment analysis performed on the lifespan of a user’s Facebook timeline, we can now measure the propensity of a user to portray themselves in opposition to their truthful, psychological baseline.We propose that researchers can apply this method of personality isolation to their analyses of publically sourced data in order to mitigate the effects of self-representation. This supports the goal of (Big) data-driven personality research being both precise and accurate. Such an approach has diverse applications in that it allows for a new personality-based estimator from which to deduce generalizations from publically accessible text onto the general population. With self-representation identified and removed, a valid measurement of psychometrics without necessitating expensive surveys or interviews is created.A limitation is the sample size, which disallows larger statements about linguistic subgroups; the non-English samples are too small for meaningful statistics. While larger than similar cyberpsychology studies found in the related work in terms of both participant number and volume of text, the study is still smaller than the largest Facebook studies to date ,44,48. AExtensions of this research are closely linked to its limitations. Cross-platform analysis of the same user for their various public profiles would give future work a more nuanced view in the ways that social media users self-represent to different audiences. Such a work would fill research gaps in ‘best’ platform usage for information disbursement, creation, and influence, as well as impact for a given network. A network analysis of users and the resulting textured understanding of how users cluster and complement within a network would be a good area of future research. Such an approach would also support answering the questions of why social media users self-represent in the way they do, given a particular site.S1 Text(DOCX)Click here for additional data file.S1 TableModel ID O–Openness; Model ID C—Conscientiousness; Model ID E–Extraversion; Model ID A–Agreeableness; Model ID N—Neuroticism(PDF)Click here for additional data file.


Hyperbaric oxygen therapy (HBOT) has been shown to be efficacious in treating various conditions, including perianal Crohn’s disease. Here we present a case of a 59-year-old male with a history of ulcerative colitis, who underwent a total proctocolectomy and two-stage J-pouch construction. He later developed chronic antibiotic-refractory pouchitis with endoscopic features of ischemia. At the completion of HOBT—a total of 20 sessions of 100% oxygen at 2.5–3.0 atmospheres absolute for 60–90 minutes per session—a repeat pouchoscopy showed marked improvement of endoscopic mucosal inflammation. HBOT is known to increase tissue oxygenation, reduce tissue hypoxia, alter inflammatory pathways and promote tissue healing. This case demonstrated the therapeutic role of HBOT as well as the possible disease mechanism in chronic antibiotic-refractory pouchitis. Hyperbaric oxygen therapy (HBOT) has been found to be safe and efficacious in the treatment of chronic wounds and inflammatory conditions, including inflammatory bowel disease (IBD) . The theThe patient was a 59-year-old male who presented to our Pouch Center with recalcitrant pouchitis, characterized by bowel frequency, hematochezia, urgency, lower abdominal pain and nocturnal incontinence. He was a former smoker (15-pack-years) with previous medical history of perforated diverticulitis in 2001. He was later diagnosed as having ulcerative colitis (UC) in 2007. He developed steroid-refractory UC, which necessitated surgical intervention with total proctocolectomy and a two-stage J-pouch construction in the same year. The patient remained asymptomatic following closure of the ileostomy but developed an incisional hernia 1.5 years later, which was repaired laparoscopically with mesh placement. He later developed increased bowel frequency, hematochezia, a burning sensation with bowel movements and bowel incontinence. He was diagnosed with pouchitis and treated with ciprofloxacin. In 2013, his symptoms progressively worsened, with increased lower abdominal pain and bleeding. He was treated with metronidazole and started on mesalamine suppositories. He continued to be symptomatic and additional treatment with hydrocortisone rectal foam for two weeks could not alleviate his symptoms. Pouchoscopy was performed, which showed ulcerated and nodular mucosa at the distal 10 cm of afferent limb side of the pouch body, the pattern consistent with ischemic pouchitis . HBOT waPouchitis is the most common long-term complication after restorative proctocolectomy with ileal pouch-anal anastomosis. From the etiopathogenetic perspective, pouchitis can broadly be categorized into microbiome-associated, autoimmune-associated, and ischemia-associated phenotypes. CARP is one of the most challenging disorders of the ileal pouch, which can lead to pouch failure. Ischemia plays an important role in the pathogenesis of CARP . The patHBOT has been successful in treating IBD, particularly CD perianal disease, myocutaneous flap repairs and chronic wounds , 3. The