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Aims/hypothesis Diabetic gastroenteropathy frequently causes debilitating gastrointestinal symptoms. Previous uncontrolled studies have shown that transcutaneous vagal nerve stimulation (tVNS) may improve gastrointestinal symptoms. To investigate the effect of cervical tVNS in individuals with diabetes suffering from autonomic neuropathy and gastrointestinal symptoms, we conducted a randomised, sham-controlled, double-blind (participants and investigators were blinded to the allocated treatment) study. Methods This study included adults (aged 20–86) with type 1 or 2 diabetes, gastrointestinal symptoms and autonomic neuropathy recruited from three Steno Diabetes Centres in Denmark. Participants were randomly allocated 1:1 to receive active or sham stimulation. Active cervical tVNS or sham stimulation was self-administered over two successive study periods: 1 week of four daily stimulations and 8 weeks of two daily stimulations. The primary outcome measures were gastrointestinal symptom changes as measured using the gastroparesis cardinal symptom index (GCSI) and the gastrointestinal symptom rating scale (GSRS). Secondary outcomes included gastrointestinal transit times and cardiovascular autonomic function. Results Sixty-eight participants were randomised to the active group, while 77 were randomised to the sham group. Sixty-three in the active and 68 in the sham group remained for analysis in study period 1, while 62 in each group were analysed in study period 2. In study period 1, active and sham tVNS resulted in similar symptom reductions (GCSI: −0.26 ± 0.64 vs −0.17 ± 0.62, p=0.44; GSRS: −0.35 ± 0.62 vs −0.32 ± 0.59, p=0.77; mean ± SD). In study period 2, active stimulation also caused a mean symptom decrease that was comparable to that observed after sham stimulation (GCSI: −0.47 ± 0.78 vs −0.33 ± 0.75, p=0.34; GSRS: −0.46 ± 0.90 vs −0.35 ± 0.79, p=0.50). Gastric emptying time was increased in the active group compared with sham (23, Aims/hypothesis: Diabetic gastroenteropathy frequently causes debilitating gastrointestinal symptoms. Previous uncontrolled studies have shown that transcutaneous vagal nerve stimulation (tVNS) may improve gastrointestinal symptoms. To investigate the effect of cervical tVNS in individuals with diabetes suffering from autonomic neuropathy and gastrointestinal symptoms, we conducted a randomised, sham-controlled, double-blind (participants and investigators were blinded to the allocated treatment) study. Methods: This study included adults (aged 20–86) with type 1 or 2 diabetes, gastrointestinal symptoms and autonomic neuropathy recruited from three Steno Diabetes Centres in Denmark. Participants were randomly allocated 1:1 to receive active or sham stimulation. Active cervical tVNS or sham stimulation was self-administered over two successive study periods: 1 week of four daily stimulations and 8 weeks of two daily stimulations. The primary outcome measures were gastrointestinal symptom changes as measured using the gastroparesis cardinal symptom index (GCSI) and the gastrointestinal symptom rating scale (GSRS). Secondary outcomes included gastrointestinal transit times and cardiovascular autonomic function. Results: Sixty-eight participants were randomised to the active group, while 77 were randomised to the sham group. Sixty-three in the active and 68 in the sham group remained for analysis in study period 1, while 62 in each group were analysed in study period 2. In study period 1, active and sham tVNS resulted in similar symptom reductions (GCSI: −0.26 ± 0.64 vs −0.17 ± 0.62, p=0.44; GSRS: −0.35 ± 0.62 vs −0.32 ± 0.59, p=0.77; mean ± SD). In study period 2, active stimulation also caused a mean symptom decrease that was comparable to that observed after sham stimulation (GCSI: −0.47 ± 0.78 vs −0.33 ± 0.75, p=0.34; GSRS: −0.46 ± 0.90 vs −0.35 ± 0.79, p=0.50). Gastric emptying time was increased in the active group compared with sham (23 min vs −19 min, p=0.04)

Background: Diabetes-induced gastrointestinal (GI) symptoms are common but difficult to correctly diagnose and manage. We used multi-segmental magnetic resonance imaging (MRI) to evaluate structural and functional GI parameters in diabetic patients and to study the association with their symptomatic presentation. Methods: Eighty-six participants (46 with diabetes and GI symptoms, 40 healthy controls) underwent baseline and post-meal MRI scans at multiple timepoints. Questionnaires were collected at inclusion and following the scans. Data were collected from the stomach, small bowel, and colon. Associations between symptoms and collected data were explored. Utilizing machine learning, we determined which features differentiated the two groups the most. Key Results: The patient group reported more symptoms at inclusion and during MRI scans. They showed 34% higher stomach volume at baseline, 40% larger small bowel volume, 30% smaller colon volume, and less small bowel motility postprandially. They also showed positive associations between gastric volume and satiety scores, gastric emptying time and reflux scores, and small bowel motility and constipation scores. No differences in gastric emptying were observed. Small bowel volume and motility were used as inputs to a classification tool that separated patients and controls with 76% accuracy. Conclusions: In this work, we studied structural and functional differences between patients with diabetes and GI symptoms and healthy controls and observed differences in stomach, small bowel, and colon volumes, as well as an adynamic small bowel in patients with diabetes and GI symptoms. Associations between recorded parameters and perceived symptoms were also explored and discussed.

Background: Gastrointestinal symptoms originating from different segments overlap and complicate diagnosis and treatment. In this study, we aimed to develop and test a pan-alimentary framework for the evaluation of gastrointestinal (GI) motility and different static endpoints based on magnetic resonance imaging (MRI) without contrast agents or bowel preparation. Methods: Twenty healthy volunteers (55.6 ± 10.9 years, BMI 30.8 ± 9.2 kg/m2) underwent baseline and post-meal MRI scans at multiple time points. From the scans, the following were obtained: Gastric segmental volumes and motility, emptying half time (T50), small bowel volume and motility, colonic segmental volumes, and fecal water content. Questionnaires to assess GI symptoms were collected between and after MRI scans. Key results: We observed an increase in stomach and small bowel volume immediately after meal intake from baseline values (p<.001 for the stomach and p=.05 for the small bowel). The volume increase of the stomach primarily involved the fundus (p<.001) in the earliest phase of digestion with a T50 of 92.1 ± 35.3 min. The intake of the meal immediately elicited a motility increase in the small bowel (p<.001). No differences in colonic fecal water content between baseline and 105 min were observed. Conclusion & Inferences: We developed a framework for a pan-alimentary assessment of GI endpoints and observed how different dynamic and static physiological endpoints responded to meal intake. All endpoints aligned with the current literature for individual gut segments, showing that a comprehensive model may unravel complex and incoherent gastrointestinal symptoms in patients.

Background: Gastrointestinal dysmotility may exist without concomitant symptoms. We hypothesize that asymptomatic individuals with diabetes have altered gastrointestinal function associated with age, cardiac vagal tone and glycaemic control. Methods: One hundred fifty-four asymptomatic participants (61 with type 1 diabetes (T1D), 70 type 2 diabetes (T2D) and 23 healthy volunteers (HV)) underwent wireless motility capsule investigation. Transit times, motility indices and pH were retrieved. Age, cardiac vagal tone, glucose and haemoglobin A1c levels were collected. Results: In T1D, prolongation of colonic (p = 0.03) and whole-gut transit times (p = 0.04) were shown. Transpyloric pH rise was decreased in T1D (p = 0.001) and T2D (p = 0.007) and was associated with cardiac vagal tone (p = 0.03) or glucose (p = 0.04) and haemoglobin A1c (p = 0.005). Ileocaecal pH fall was decreased in T2D (p < 0.001). Conclusions: Gastrointestinal function was altered in asymptomatic individuals with diabetes. These findings call for further investigations of gastrointestinal function in order to identify risk factors or even predictors for diabetic enteropathy, particularly when glycaemic control is impaired.

Introduction A high proportion of people with diabetes experience gastrointestinal (GI) symptoms, which may be manifestations of diabetic autonomic neuropathy (DAN). The current treatment regime is ineffective and associated with major side effects. Transcutaneous vagal nerve stimulation (tVNS) is a new therapeutic option, which has been shown to increase GI motility and reduce inflammatory responses. As vagus is the main neuronal pathway for extrinsic coordination of GI secretion and motility, we hypothesise that tVNS will improve DAN-induced GI symptoms in subjects with diabetes. Methods and analysis The DAN-VNS study is a randomised multicentre clinical trial investigating the effect of short-term, high intensity as well as long-term, medium-intensity tVNS on GI symptom alleviation in 120 subjects with diabetes. The primary outcome consists of changes from baseline in subjective ratings of symptom severity. Secondary outcomes include changes in gastric motility and GI transit time measured by MRI and wireless motility capsule. Moreover, cardiovascular and sudomotor function, glycaemic control, brain sensory processing and presence of low-grade inflammation will be investigated as secondary outcome measures. Lastly, 15 responders of tVNS treatment will be included in an explorative, randomised, cross-over study, in which the acute endocrine and metabolic response to short-term tVNS will be investigated. Ethics and dissemination The study has been approved by the North Denmark Region Committee on Health Research Ethics (N-20190020). Results will be published in relevant international peer-reviewed journals. Trial registration number NCT04143269.

Questa tesi esplora il ruolo pionieristico di Domenico Guglielmini nell’idraulica e nella fluidodinamica nei secoli XVII e XVIII, con focus sul contesto storico e scientifico dell’epoca. Divisa in quattro capitoli, la ricerca inizia con una panoramica sulla storia della fluidodinamica, approfondendo inoltre l’importanza dell’idraulica a Bologna. Si analizza dettagliatamente il libro Della Natura de’ Fiumi, per poi mettere in luce la figura di Guglielmini come scienziato che si colloca nel solco della tradizione galileiana. Le due appendici offrono un confronto tra Guglielmini e Galileo e analizzano le immagini presenti nel libro. La tesi si propone di offrire un’indagine su un tema poco esplorato come quello dell’idraulica, collegandolo alla figura di Guglielmini, il primo a detenere una cattedra di Idrometria all’Universita` di Bologna. Emerge il ruolo fondamentale di Guglielmini come matematico e il suo contributo allo sviluppo del metodo scientifico nell’ambito idraulico, rilevante sia politicamente che culturalmente.