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C M Casciola - One of the best experts on this subject based on the ideXlab platform.

  • Pressure control in interfacial systems: Atomistic simulations of vapor nucleation.
    The Journal of chemical physics, 2018
    Co-Authors: Serena Marchiò, Simone Meloni, Chantal Valeriani, Alessandro Giacomello, C M Casciola
    Abstract:

    A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular Barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) Barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10-15 kBT on the free-energy barrier, corresponding to an error of 104-106 s-1σ-3 on the nucleation rate. A mechanical (local) Barostat is proposed which heals the artifacts for the considered case of vapor nucleation.

  • pressure control in interfacial systems atomistic simulations of vapor nucleation
    Journal of Chemical Physics, 2018
    Co-Authors: Serena Marchiò, Simone Meloni, Chantal Valeriani, Alessandro Giacomello, C M Casciola
    Abstract:

    A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular Barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) Barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10–15 kBT on the free-energy barrier, corresponding to an error of 104–106 s−1σ−3 on the nucleation rate. A mechanical (local) Barostat is proposed which heals the artifacts for the considered case of vapor nucleation.A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular Barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) Barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10–15 kBT on the free-energy barrier, co...

Ad A.m. Masclee - One of the best experts on this subject based on the ideXlab platform.

  • Alternative procedure to shorten rectal Barostat procedure for the assessment of rectal compliance and visceral perception: a feasibility study.
    Journal of gastroenterology, 2012
    Co-Authors: Steven Vanhoutvin, Ad A.m. Masclee, Patrick J. Lindsey, Daisy Jonkers, Frederik Jan Troost, T. O. C. Kilkens, Konraad Venema, Robert-jan M. Brummer
    Abstract:

    BACKGROUND: Barostat methodology is widely used for assessing visceral perception. Different Barostat protocols are described with respect to the measurement of rectal compliance and visceral perception. The choice of protocols affects the duration, which is normally 60-90 min, and accuracy of the procedure. This study aimed to shorten the procedure by using the semi-random distension protocol for both compliance and visceral perception measurement and a correction based on rectal capacity (RC) instead of minimal distension pressure (MDP). METHODS: Twelve irritable bowel syndrome (IBS) patients (7 females) and 11 healthy controls (8 females) underwent a Barostat procedure. Compliance was determined during both a staircase distension and a semi-random protocol. Visceral perception data were compared as a function of pressure or relative volume, corrected for MDP or RC, respectively. RESULTS: Compliance measurement using the semi-random protocol instead of the staircase distension protocol resulted in an overestimation in healthy volunteers, but not in IBS patients. The overall conclusion that IBS patients had a lower compliance compared to controls was not different between protocols. Data presentation of the visceral perception scores as a function of corrected volume instead of pressures corrected for MDP did not alter the conclusion that sensation scores in IBS patients were higher as compared to healthy controls. CONCLUSIONS: This study showed that Barostat procedures may be shortened by approximately 20 min, without losing the ability to discriminate between healthy controls and IBS patients. A correction for RC instead of MDP may improve the accuracy of the procedure.

  • Does meal ingestion enhance sensitivity of visceroperception assessment in irritable bowel syndrome
    Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society, 2011
    Co-Authors: Samefko Ludidi, José M. Conchillo, Daniel Keszthelyi, C.j.a. Koning, Steven Vanhoutvin, Patrick J. Lindsey, A.m. Leufkens, Joanna W. Kruimel, Daisy Jonkers, Ad A.m. Masclee
    Abstract:

    Background  Visceral hypersensitivity is frequently observed in irritable bowel syndrome (IBS). Previous studies have shown that administration of a meal can aggravate symptoms or increase visceroperception in IBS patients. We investigated whether meal ingestion could increase the sensitivity of the Barostat procedure for the detection of visceral hypersensitivity in IBS patients. Methods  Seventy-one IBS patients and 30 healthy controls (HC) were included in the study. All subjects underwent a Barostat procedure under fasted and postprandial conditions to measure visceroperception. Urge, discomfort, and pain were scored on a visual analog scale. Furthermore, percentages of hypersensitive IBS patients and HC were calculated and dynamic rectal compliance was assessed. Key Results  In IBS patients, urge, discomfort, and pain scores were significantly increased postprandially vs the fasted state. The HC showed increased scores for urge and pain only. Rectal dynamic compliance remained unaltered in both groups. Postprandial hypersensitivity percentages did not significantly differ vs the fasted state in IBS patients, nor in HC. Conclusions & Inferences  Postprandial Barostat measurement enhances visceroperception in IBS but has no added value to detect visceral hypersensitivity in individual IBS patients.

  • Journal of Magnetic Resonance Imaging - Gastric Volume Changes in Response to a Meal : Validation of Magnetic Resonance Imaging Versus the Barostat
    Journal of magnetic resonance imaging : JMRI, 2011
    Co-Authors: Jeoffrey J L Haans, Ingrid M. De Zwart, Albert De Roos, Paul H. C. Eilers, Johan H. C. Reiber, Joost Doornbos, Ad A.m. Masclee
    Abstract:

    Purpose: To determine the accuracy of magnetic resonance imaging (MRI) volume scans: 1) to measure known meal volumes in vitro, and 2) to compare volume changes in response to a meal measured with the Barostat with those measured with MRI in vivo. Materials and Methods: Polyethylene bags were filled with known volumes and MRI volume scans were performed to determine the accuracy of the volume measurements. Barostat measurements and MRI volume scans were performed simultaneously in 14 healthy subjects before and up to 90 minutes after ingestion of a liquid meal. Results: In vitro MRI-determined volumes showed an excellent linear relationship (r = 0.995, P < 0.001) with actual meal volumes. Although fasting gastric volume, postprandial gastric volume, and relaxation volume measured with MRI were significantly larger compared to volumes measured with the Barostat, volumes determined with both techniques showed excellent correlation. Conclusion: Volumes in the range of postprandial meal volumes are accurately measured with MRI. MRI is a noninvasive technique to measure stomach volumes and volume changes in response to a meal. Volume changes in response to a meal measured with MRI correlate perfectly with those measured with the Barostat device. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc.

  • gastric volume changes in response to a meal validation of magnetic resonance imaging versus the Barostat
    Journal of Magnetic Resonance Imaging, 2011
    Co-Authors: Jeoffrey J L Haans, Ingrid M. De Zwart, Albert De Roos, Paul H. C. Eilers, Johan H. C. Reiber, Joost Doornbos, Ad A.m. Masclee
    Abstract:

    Purpose: To determine the accuracy of magnetic resonance imaging (MRI) volume scans: 1) to measure known meal volumes in vitro, and 2) to compare volume changes in response to a meal measured with the Barostat with those measured with MRI in vivo. Materials and Methods: Polyethylene bags were filled with known volumes and MRI volume scans were performed to determine the accuracy of the volume measurements. Barostat measurements and MRI volume scans were performed simultaneously in 14 healthy subjects before and up to 90 minutes after ingestion of a liquid meal. Results: In vitro MRI-determined volumes showed an excellent linear relationship (r = 0.995, P < 0.001) with actual meal volumes. Although fasting gastric volume, postprandial gastric volume, and relaxation volume measured with MRI were significantly larger compared to volumes measured with the Barostat, volumes determined with both techniques showed excellent correlation. Conclusion: Volumes in the range of postprandial meal volumes are accurately measured with MRI. MRI is a noninvasive technique to measure stomach volumes and volume changes in response to a meal. Volume changes in response to a meal measured with MRI correlate perfectly with those measured with the Barostat device. J. Magn. Reson. Imaging 2011;. © 2011 Wiley-Liss, Inc.

  • Gastric accommodation and motility are influenced by the Barostat device: Assessment with magnetic resonance imaging.
    American journal of physiology. Gastrointestinal and liver physiology, 2006
    Co-Authors: Ingrid M. De Zwart, Albert De Roos, Paul Verbeek, Paul H. C. Eilers, Jeoffrey J L Haans, Ad A.m. Masclee
    Abstract:

    The Barostat is considered the gold standard for evaluation of proximal gastric motility especially for the accommodation response to a meal. The procedure is invasive because it involves the intro...

Jan Tack - One of the best experts on this subject based on the ideXlab platform.

  • The effect of prucalopride on gastric sensorimotor function and satiation in healthy volunteers.
    Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society, 2021
    Co-Authors: Florencia Carbone, Tim Vanuytsel, Jan Tack
    Abstract:

    BACKGROUND Gastric motor function alterations have been implicated in the pathogenesis of functional dyspepsia with postprandial distress syndrome (PDS). Prucalopride, a 5-TH4 agonist, is known to stimulate gastrointestinal motility. We aimed to evaluate the effect of prucalopride on gastric sensorimotor function in healthy subjects (HV). METHODS Barostat and intragastric pressure (IGP) measurements were performed in 17 HV (59% females, age 29.4 ± 2.7 y) after treatment with placebo or prucalopride (2 mg) (single-blind cross-over). Isobaric stepwise distensions and gastric sensations were assessed to determine gastric compliance and sensitivity. Gastric accommodation (GA) with the Barostat was quantified before and after ingestion of 200 ml of a nutrient drink (ND). GA measured by IGP was quantified as the drop of IGP from baseline during the intragastric infusion of ND until maximal satiation (60 ml/min). KEY RESULTS Prucalopride did not affect Barostat assessed gastric compliance or sensitivity. No differences were observed in GA after prucalopride. During the Barostat study, 10 min after the meal, 7 HVs reported significantly higher ratings for nausea after prucalopride (p 

  • the effect of mirtazapine on gastric accommodation gastric sensitivity to distention and nutrient tolerance in healthy subjects
    Neurogastroenterology and Motility, 2017
    Co-Authors: Florencia Carbone, Tim Vanuytsel, Jan Tack
    Abstract:

    Background Disturbances of gastric motor function of functional dyspepsia (FD) have been implicated in the pathogenesis of the symptoms, and hence, motility modifying agents are considered for its treatment. Mirtazapine was recently shown to improve symptoms and increase nutrient tolerance in FD patients with weight loss. We aim to evaluate the effect of mirtazapine on gastric sensorimotor function in healthy volunteers (HV). Methods Thirty-one HV underwent an intragastric pressure (IGP) and Barostat measurements on separate days before and after 3 weeks of placebo or mirtazapine (15 mg). Gastric compliance, sensitivity and accommodation (GA) measured by the Barostat. GA was quantitated as the difference (delta) in intra-balloon volume before and after ingestion of 200 mL of a nutrient drink (ND). GA measured by IGP was quantitated as the drop of IGP from baseline during the intragastric infusion of ND until maximal satiation. Key Results Mirtazapine significantly increased the bodyweight of subjects (67.8±3.7 to 69.1±3.7 kg; P=.01). Barostat results showed no effect on gastric compliance, sensitivity, and GA. Nutrient tolerance was not affected after treatment (1170±129.4 vs 1104±133.6 kcal; P=.4), and mirtazapine was associated with lower symptom ratings. The IGP drop during meal ingestion was significantly suppressed (area under the curve: −43.3±4.5 mm Hg vs −28.9±3.1 mm Hg; P=.005). Conclusions & Inferences In HVs, the occurrence of weight gain and decreased meal-induced symptoms in spite of a suppressed meal-induced IGP drop, point towards a central mode of action. Mirtazapine does not display changes in gastric sensorimotor function that could explain its beneficial effects on symptoms and nutrient tolerance in FD.

  • The Role of Gastric Sensorineural Dysfunction in Functional Dyspepsia
    Frontiers of Gastrointestinal Research, 2014
    Co-Authors: Jan Tack
    Abstract:

    Visceral hypersensitivity is an attractive pathophysiological concept in functional dyspepsia (FD) and other functional disorders. Gastric Barostat studies have established that a subset of FD patient

  • Endogenously released opioids mediate meal-induced gastric relaxation via peripheral mu-opioid receptors.
    Alimentary Pharmacology and Therapeutics, 2010
    Co-Authors: Pieter Janssen, Hans Pottel, Rita Vos, Jan Tack
    Abstract:

    Background/Aim We previously showed that the centrally-acting mu-opioid receptor antagonist naloxone inhibited meal-induced gastric accommodation. In order to study the role of peripheral mu-opioid receptors in the regulation of gastric tone and food intake we compared the effects of naloxone with the peripherally-restricted mu-opioid receptor antagonist methylnaltrexone. Methods Methylnaltrexone (12 mg subcutaneous injection), naloxone (20 µg kg-1 h-1 intravenous infusion after 0.4 mg bolus) and placebo were studied in 23 healthy volunteers. Gastric volume was recorded using an intragastric bag held at constant pressure connected to a Barostat, with administration of a nutrient drink after 30 minutes. Pressure in the stomach was measured during intragastric nutrient drink infusion until the volunteers scored maximal satiation. Data were represented as mean±SEM and compared using paired t-tests and mixed model analysis. Results Methylnaltrexone significantly inhibited the volume increase after food intake as assessed with the Barostat (p

  • Effect of acute citalopram treatment on gastric motor function and nutrient tolerance in healthy volunteers.
    Alimentary Pharmacology and Therapeutics, 2010
    Co-Authors: Pieter Janssen, Rita Vos, Lukas Van Oudenhove, Cindy Casteels, Kristin Verbeke, Jan Tack
    Abstract:

    Background It is unclear whether endogenous serotonin release is involved in the regulation of gastric motility and food intake Aim We aimed to study the effect of acute administration of the selective serotonin reuptake inhibitor citalopram on gastric motor function in man. Methods 19 healthy volunteers underwent a gastric Barostat, gastric emptying and/or a drinking test after treatment with either placebo or citalopram (20 mg intravenously). In the Barostat protocol a flaccid bag was introduced in the stomach and inflated at intra-abdominal pressure +2 mmHg, volume was recorded before and after administration of a liquid meal (300 kcal). Gastric emptying for solids and liquids was simultaneously assessed using the 14C-octanoic acid/13C-Glycine breath test. During the drink test volunteers drank at a rate of 15 ml min-1 until maximal satiation. Citalopram was compared to placebo using t-tests and mixed model analysis. Results Citalopram induced a significant preprandial gastric relaxation (volume increase of 154±55 ml vs. -38±33 ml after placebo treatment; p

Serena Marchiò - One of the best experts on this subject based on the ideXlab platform.

  • Pressure control in interfacial systems: Atomistic simulations of vapor nucleation.
    The Journal of chemical physics, 2018
    Co-Authors: Serena Marchiò, Simone Meloni, Chantal Valeriani, Alessandro Giacomello, C M Casciola
    Abstract:

    A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular Barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) Barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10-15 kBT on the free-energy barrier, corresponding to an error of 104-106 s-1σ-3 on the nucleation rate. A mechanical (local) Barostat is proposed which heals the artifacts for the considered case of vapor nucleation.

  • pressure control in interfacial systems atomistic simulations of vapor nucleation
    Journal of Chemical Physics, 2018
    Co-Authors: Serena Marchiò, Simone Meloni, Chantal Valeriani, Alessandro Giacomello, C M Casciola
    Abstract:

    A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular Barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) Barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10–15 kBT on the free-energy barrier, corresponding to an error of 104–106 s−1σ−3 on the nucleation rate. A mechanical (local) Barostat is proposed which heals the artifacts for the considered case of vapor nucleation.A large number of phenomena of scientific and technological interest involve multiple phases and occur at constant pressure of one of the two phases, e.g., the liquid phase in vapor nucleation. It is therefore of great interest to be able to reproduce such conditions in atomistic simulations. Here we study how popular Barostats, originally devised for homogeneous systems, behave when applied straightforwardly to heterogeneous systems. We focus on vapor nucleation from a super-heated Lennard-Jones liquid, studied via hybrid restrained Monte Carlo simulations. The results show a departure from the trends predicted for the case of constant liquid pressure, i.e., from the conditions of classical nucleation theory. Artifacts deriving from standard (global) Barostats are shown to depend on the size of the simulation box. In particular, for Lennard-Jones liquid systems of 7000 and 13 500 atoms, at conditions typically found in the literature, we have estimated an error of 10–15 kBT on the free-energy barrier, co...

Hein G. Gooszen - One of the best experts on this subject based on the ideXlab platform.

  • elicitation of transient lower oesophageal sphincter relaxations in response to gastric distension and meal ingestion
    Neurogastroenterology and Motility, 2002
    Co-Authors: Robert C.h. Scheffer, Louis M. A. Akkermans, J. E. Bais, J. M. M. Roelofs, A. J. P. M. Smout, Hein G. Gooszen
    Abstract:

    AbstractThe aim of this study was to compare the effect of graded gastric Barostat distension and meal-induced fundic relaxation on the elicitation of transient lower oesophageal sphincter relaxation (TLOSR). In 15 healthy subjects, stepwise fundic distension and oesophageal manometry were performed simultaneously. Next, the effect of meal ingestion on proximal stomach volume and lower oesophageal sphincter function was studied. During stepwise Barostat distension of the proximal stomach, a significant linear correlation between intragastric pressure (r = 0.91; P < 0.01) and the TLOSR rate during inflation and subsequent deflation (r = 0.96; P < 0.01) was found. A similar relationship was found for volume. In addition, after meal ingestion, the TLOSR rate increased significantly from 1.40 ± 3 to 5.4 ± 1.5 h−1 (P < 0.01) and 5.2 ± 1.7 h−1 (P < 0.01), respectively, during the first and second 30-min postprandially. However, at similar calculated intragastric volumes, Barostat distension led to a significantly higher TLOSR rate than the meal. Similarly, distension-induced increase in gastric wall tension, estimated from the measured bag pressure and volume using Laplace's law, was associated with significantly higher TLOSR rates (P < 0.01). In conclusion, the rate of TLOSRs in healthy volunteers is directly related to the degree of proximal gastric distension and pressure-controlled Barostat distension is a more potent trigger of TLOSRs than a meal. The latter finding suggests that tension receptor activation is an important stimulus for TLOSRs.

  • Elicitation of transient lower oesophageal sphincter relaxations in response to gastric distension and meal ingestion.
    Neurogastroenterology and motility : the official journal of the European Gastrointestinal Motility Society, 2002
    Co-Authors: Robert C.h. Scheffer, Louis M. A. Akkermans, J. E. Bais, J. M. M. Roelofs, A. J. P. M. Smout, Hein G. Gooszen
    Abstract:

    AbstractThe aim of this study was to compare the effect of graded gastric Barostat distension and meal-induced fundic relaxation on the elicitation of transient lower oesophageal sphincter relaxation (TLOSR). In 15 healthy subjects, stepwise fundic distension and oesophageal manometry were performed simultaneously. Next, the effect of meal ingestion on proximal stomach volume and lower oesophageal sphincter function was studied. During stepwise Barostat distension of the proximal stomach, a significant linear correlation between intragastric pressure (r = 0.91; P