Artifact Rejection Methodology Enables Continuous, Noninvasive Measurement of Gastric Myoelectric Activity in Ambulatory Subjects.

The increasing prevalence of functional and motility gastrointestinal (GI) disorders is at odds with bottlenecks in their diagnosis, treatment, and follow-up. Lack of noninvasive approaches means that only specialized centers can perform objective assessment procedures. Abnormal GI muscular activity, which is coordinated by electrical slow-waves, may play a key role in symptoms. As such, the electrogastrogram (EGG), a noninvasive means to continuously monitor gastric electrical activity, can be used to inform diagnoses over broader populations. However, it is seldom used due to technical issues: inconsistent results from single-channel measurements and signal artifacts that make interpretation difficult and limit prolonged monitoring. Here, we overcome these limitations with a wearable multi-channel system and artifact removal signal processing methods. Our approach yields an increase of 0.56 in the mean correlation coefficient between EGG and the clinical "gold standard", gastric manometry, across 11 subjects (p < 0.001). We also demonstrate this system's usage for ambulatory monitoring, which reveals myoelectric dynamics in response to meals akin to gastric emptying patterns and circadian-related oscillations. Our approach is noninvasive, easy to administer, and has promise to widen the scope of populations with GI disorders for which clinicians can screen patients, diagnose disorders, and refine treatments objectively

Review on electrical impedance tomography: Artificial intelligence methods and its applications

© 2019 by the authors. Electrical impedance tomography (EIT) has been a hot topic among researchers for the last 30 years. It is a new imaging method and has evolved over the last few decades. By injecting a small amount of current, the electrical properties of tissues are determined and measurements of the resulting voltages are taken. By using a reconstructing algorithm these voltages then transformed into a tomographic image. EIT contains no identified threats and as compared to magnetic resonance imaging (MRI) and computed tomography (CT) scans (imaging techniques), it is cheaper in cost as well. In this paper, a comprehensive review of efforts and advancements undertaken and achieved in recent work to improve this technology and the role of artificial intelligence to solve this non-linear, ill-posed problem are presented. In addition, a review of EIT clinical based applications has also been presented

Применение финитных базисных сплайнов при восстановлении сигналов электрогастроэнтерографии

Electrogastroenterography is the promising method of examination of the motion activity of the digestive system. It is based on the measurement and further processing of bioelectric signals. During last years the progress in the development of electrophysiological methods of diagnostics is due to the computer processing of measuring signals. This paper is devoted to the aspects of organization of measurements in electrogastroenterography. In the paper, we present an introduction to the problem domain; analyze the information structure of a measuring signal; review the diagnostics parameters obtained as a result of spectral analysis of electrogastroenterography signals; discuss the tasks of automation of diagnostics. We propose the new method of sampling of gastroenterograms. It considers the factor of the finite length of measurement sessions and spectral properties of signals. Representation of a signal as the finite sum of finite cardinal B-splines with integer degrees is used in the method. The computer experiment for testing the accuracy of signal reconstruction with parameters of measuring session used in electrogastroenterography was conducted.Электрогастроэнтерография — перспективный метод обследования сократительной активности органов пищеварительной системы, основанный на съеме и последующей обработке биоэлектрических сигналов. Прогресс в развитии электрофизиологических методов диагностики в последние годы во многом обеспечен возможностью компьютерной обработки измерительных сигналов. Данная статья посвящена вопросам организации измерений в электрогастроэнтерографии. Дано введение в предметную область, проанализирован информационный состав измерительных сигналов электрогастроэнтерографии, приведены диагностические показатели, получаемые в результате спектрального анализа сигналов, рассмотрены задачи автоматизации диагностики. Предложен новый метод выбора частоты отсчетов гастроэнтерограмм, учитывающий фактор конечной длительности измерительных сеансов и спектральных свойств сигнала. В предлагаемом методе применяется разложение сигнала в виде конечной суммы финитных кардинальных В-сплайнов целых степеней. Проведен вычислительный эксперимент для определения точности восстановления сигнала при используемых в электрогастроэнтерографии параметрах измерительного сеанса

First translational consensus on terminology and definitions of colonic motility in animals and humans studied by manometric and other techniques

Alterations in colonic motility are implicated in the pathophysiology of bowel disorders, but high-resolution manometry of human colonic motor function has revealed that our knowledge of normal motor patterns is limited. Furthermore, various terminologies and definitions have been used to describe colonic motor patterns in children, adults and animals. An example is the distinction between the high-amplitude propagating contractions in humans and giant contractions in animals. Harmonized terminology and definitions are required that are applicable to the study of colonic motility performed by basic scientists and clinicians, as well as adult and paediatric gastroenterologists. As clinical studies increasingly require adequate animal models to develop and test new therapies, there is a need for rational use of terminology to describe those motor patterns that are equivalent between animals and humans. This Consensus Statement provides the first harmonized interpretation of commonly used terminology to describe colonic motor function and delineates possible similarities between motor patterns observed in animal models and humans in vitro (ex vivo) and in vivo. The consolidated terminology can be an impetus for new research that will considerably improve our understanding of colonic motor function and will facilitate the development and testing of new therapies for colonic motility disorders. This Consensus Statement provides a conceptual and methodological framework to expand research on colonic motility in experimental animals and humans. The work is intended to facilitate the development of new drugs for common colonic motility disorders and of appropriate diagnostic and therapeutic algorithms for the management of paediatric and adult patients

Mapping and Modulating the Stomach-Brain Neuroaxis

The stomach and the brain interact closely with each other. Their interactions are central to digestive functions and the “gut feeling”. The neural pathways that mediate the stomach-brain interactions include the vagus nerve and the thoracic nerve. Through these nerves, the stomach can relay neural signals to a number of brain regions that span a central gastric network. This gastric network allows the brain to monitor and regulate gastric physiology and allows the stomach to influence emotion and cognition. Impairment of this gastric network may lead to both gastric and neurological disorders, e.g., anxiety, gastroparesis, functional dyspepsia, and obesity. However, the structural constituents and functional roles of the central gastric network remain unclear. In my dissertation research, I leveraged complementary techniques to characterize the central gastric network in rats across a wide range of scales and different gastric states. I used functional magnetic resonance imaging (fMRI) to map blood-oxygen-level-dependent (BOLD) activity synchronized with gastric electrical activity and to map brain activations induced by electrical stimulation applied to the vagus nerve or its afferent terminals on the stomach. I also used neurophysiology to characterize gastric neurons in the brainstem in response to gastric electrical stimulation. My results suggest that gastric neurons in the brainstem are selective to the orientation of gastric electrical stimulation. This electrical stimulation can also evoke neural activity beyond the brainstem and drive fast blood oxygenation level dependent (BOLD) activity in the central gastric network, primarily covering the cingulate cortex, somatosensory cortex, motor cortex, and insular cortex. Stimulating the vagus nerve – the primary neural pathway between the stomach and the brain, can evoke BOLD responses across widespread brain regions partially overlapped with the brain network evoked by gastric electrical stimulation. BOLD activity within the gastric network is also coupled to intrinsic gastric activity. Specifically, gastric slow waves are synchronized with the BOLD activity in the central gastric network. The synchronization manifests itself as the phase-coupling between BOLD activity and gastric slow waves as well as the correlation between BOLD activity and power fluctuations of gastric slow waves. This synchronization is primarily supported by the vagus nerve and varies across the postprandial and fasting states. My dissertation research contributes to the foundation of mapping and characterizing the central and peripheral mechanisms of gastric interoception and sheds new light on where and how to stimulate the peripheral nerves to modulate stomach-brain interactions.PHDBiomedical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/170007/1/jccao_1.pd

The Design and Validation of a Discrete-Event Simulator for Carbohydrate Metabolism in Humans

CarbMetSim is a discrete event simulator that tracks the changes of blood glucose level of a human subject after a timed series of diet and exercises activities. CarbMetSim implements wider aspects of carbohydrate metabolism in individuals to capture the average effect of various diet/exercise routines on the blood glucose level of diabetic patients. The simulator is implemented in an object-oriented paradigm, where key organs are represented as classes in the CarbMetSim. Key organs (stomach, intestine, portal vein, liver, kidney, muscles, adipose tissue, brain and heart) are implemented to the extent necessary to simulate their impact on the production and consumption of glucose. Metabolic pathways (glucose oxidation, glycolysis and gluconeogenesis) have been taken in account in the operation of various organs. In accordance with published research, the impact of insulin and insulin resistance on the operation of various organs/pathways is captured. CarbMetSim offers broad versatility to configure the insulin production ability, the average flux along various metabolic pathways and the impact of insulin resistance on different aspects of carbohydrate metabolism. However, the CarbMetSim project has not yet been finished. There are many aspects and metabolic pathways that have not been implemented or have been implemented in a simple manner. Also, additional validation is required before the simulator can be considered ready for use by people with Diabetes

Mechanistic Analysis and Quantification of Gastrointestinal Motility: Physiological Variability and Plasma Level Implications.

The oral route of administration is still by far the most ubiquitous method of drug delivery. Development in this area still faces many challenges due to the complex inhomogeneity of the gastrointestinal environment. In particular, gastric emptying and gastrointestinal motility is not predictable and so dosing occurs randomly with respect to these physiological variables. The goal of this research is to present a mass balance analysis that captures this variation, highlighting the effects of motility and exploring how it ultimately impacts plasma levels and the relationship to bioequivalence. A mechanistic analysis is first developed describing the underlying fasted state cyclical motility and how the contents of the gastrointestinal tract are propelled. This physiologically based approach allows the estimation of potential absorption ranges based on uncontrolled variation. Validation of the simulations is based on reported gastric emptying profiles and volumetric emptying as well as previous experimental works on gastrointestinal transit times, and the bioequivalence implications of such variation are also considered. Next, a dissolution model is presented to account for the dynamics of physiological conditions along the gastrointestinal tract, including small volumes and variable pH profiles. Predicting the extent of dissolution along with transit profiles of dissolved and particulate content is crucial to approximating absorption. Ibuprofen and phenol red are used as example cases. Finally, a method for refining the gastrointestinal transit model is critical for ensuring accuracy, and a methodology is presented for extracting relevant information from intubation studies. Gastrointestinal manometry can be thought of as a stochastic process in which the indeterminacy of state transition times belies absolute periodicity of the system. To account for this inherent randomness, the use of statistical computing can identify and characterize the different phases of the gastrointestinal cycle. Specifically, a Gaussian process is used as a robust regression method to model the time-dependent evolution of the signal. As further validation, using a pressure peak detection method based on continuous wavelet transforms and subsequently a kernel density estimator as a smoothing function, regression-based motility phase classification corresponds expected pressure peak density estimates.PhDPharmaceutical SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/113403/1/arjang_1.pd

Appetite and Satiety Control-Gut Mechanisms

The prevalence of obesity and its comorbidities, particularly type 2 diabetes, cardiovascular and hepatic disease and certain cancers, continues to rise worldwide. Paradoxically, despite an increasingly obesogenic environment, particularly in Western societies, undernutrition is also extremely common. The application of novel, sophisticated techniques, particularly related to imaging and molecular biology, has substantially advanced our understanding of the mechanisms controlling appetite and energy intake. This has led to a redefinition of many concepts, including the relative importance of central versus peripheral mechanisms, recognising that the gastrointestinal (GI) tract, particularly gut hormones, plays a critical role. Given the major advance in knowledge in the field, this Special Issue provides a comprehensive overview of the GI mechanisms underlying the regulation of appetite and energy intake, as a series of definitive reviews by international authorities. The reviews address gut-related mechanisms, including nutrient sensing, gut hormones and GI motility, gut-brain communication, including the roles of the vagus and the modulation of reward perception, the roles of diet and the microbiota, as well as the abnormalities associated with eating disorders, specifically obesity and anorexia of ageing, and the beneficial effects of bariatric surgery. The reviews cover both preclinical research and studies in humans, and are complemented by a number of important original papers