The Experts below are selected from a list of 4482 Experts worldwide ranked by ideXlab platform
Yvo Ghoos - One of the best experts on this subject based on the ideXlab platform.
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oxidative breakdown of Octanoic Acid is maintained in patients with cirrhosis despite advanced disease
2003Co-Authors: Marc Van De Casteele, Yvo Ghoos, Benny Geypens, Anja Luypaerts, Johan Fevery, Frederik NevensAbstract:As an Octanoic Acid 13CO2 breath test is frequently used to test gastric emptying of solid food, the purpose of the present study was to study whether oxidative breakdown of Octanoic Acid is affected by severe liver disease. The design of our study was twofold. First, cirrhotic patients (n = 82) of varying severity were compared with healthy controls (n = 17). Values of half-time, time point of maximal expiration and cumulative recovery of Octanoic Acid breath tests (OBT) were not significantly different between them. Secondly, cirrhotic patients (n = 10) were studied before placement of transjugular intrahepatic portosystemic shunt, 4-7 days later and 1-2 months later. Values of half-time, time point of maximal expiration and cumulative recovery of consecutive OBTs did not change significantly. The OBT may therefore be a suitable test in the future to detect delayed gastric emptying of solids in cirrhotic patients with reduced liver function and portal hypertension.
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gastric emptying flow curves separated from carbon labeled Octanoic Acid breath test results
1998Co-Authors: Bart Maes, Yvo Ghoos, Benny Geypens, G Mys, Pieter Evenepoel, Paul RutgeertsAbstract:Recently, we developed the [13/14C]Octanoic Acid breath test to measure gastric emptying of solids. Although the method has been validated extensively, absorption, metabolism, and excretion of the ...
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gastric emptying in formula fed and breast fed infants measured with the 13c Octanoic Acid breath test
1997Co-Authors: Mieke Van Den Driessche, Yvo Ghoos, Kristel Peeters, Paul Marien, Hugo Devlieger, G VeeremanwautersAbstract:ABSTRACTBackground:The 13C-Octanoic Acid breath test, a noninvasive method for measuring gastric emptying, was used to compare the gastric-emptying rate of formula-fed and breast-fed infants. Octanoic Acid, a medium-chain fatty Acid marked with the stable isotope 13C is immediately absorbed in the d
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the 13c Octanoic Acid breath test a noninvasive technique to assess gastric emptying in preterm infants
1996Co-Authors: G Veeremanwauters, Bart Maes, Yvo Ghoos, Hugo Devlieger, S Van Der Schoor, N Hebbalkar, Ephrem EggermontAbstract:SummaryGastric emptying (GE) is difficult to evaluate properly in preterm infants because of the lack of safe and reliable noninvasive methods. The 13C-Octanoic Acid breath test, a noninvasive method to assess GE, was validated in adults. The aim of this study was to adapt the methodology of the 13C
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c Octanoic Acid breath test to measure gastric emptying rate of solids
1994Co-Authors: Bart Maes, Martin Hiele, Paul Rutgeerts, Yvo Ghoos, Benny Geypens, Gaston VantrappenAbstract:We have developed a breath test to measure solid gastric emptying using a standardized scrambled egg test meal (250 kcal) labeled with [14C]Octanoic Acid or [13C]Octanoic Acid. In vitro incubation studies showed that Octanoic Acid is a reliable marker of the solid phase. The breath test was validated in 36 subjects by simultaneous radioscintigraphic and breath test measurements. Nine healthy volunteers were studied after intravenous administration of 200 mg erythromycin and peroral administration of 30 mg propantheline, respectively. Erythromycin significantly enhanced gastric emptying, while propantheline significantly reduced gastric emptying rates. We conclude that the [*C]Octanoic breath test is a promising and reliable test for measuring the gastric emptying rate of solids.
Andrea Mandanici - One of the best experts on this subject based on the ideXlab platform.
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anti arrhenian behaviour of conductivity in Octanoic Acid bis 2 ethylhexyl amine systems a physico chemical study
2015Co-Authors: Pietro Calandra, Vincenzo Turco Liveri, Angela Ruggirello, Mariano Licciardi, Domenico Lombardo, Andrea MandaniciAbstract:Pure surfactant liquids and their binary mixtures, owing to the amphiphilic nature of the molecules involved, can exhibit nano-segregation and peculiar transport properties. The structural and dynamic properties of Octanoic Acid (OA)–bis(2-ethylhexyl)amine (BEEA) liquid mixtures at various compositions have been studied by Wide Angle X-ray Scattering (WAXS), 1H-NMR and broadband dielectric spectroscopy as a function of temperature. It was found that the self-assembly occurs via proton exchange between the OA COOH group and the BEEA NH one; such self-assembled local structures are affected anisotropically by a temperature increase so that the thermal dilatation is more marked in a direction perpendicular to the molecular axis whereas it is practically unaffected along its axis. Interestingly, an anti-Arrhenian behaviour of the conductivity has been found at the OA molar ratio (XOA) of around 0.66. This behaviour has been interpreted as the overall result of the competition between the tendency of OA surfactant molecules to aggregate through OA–OA H-bond formation and the establishment of hetero-adducts OA–BEEA joined to the temperature disordering effect. The potentialities of such systems as proton conducting water-free organic-based liquid systems enable them to be tailored for their direct use as liquid membranes in fuel cells but also, from a more general perspective, for the piloted design of smart materials for specific applications.
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emerging dynamics in surfactant based liquid mixtures Octanoic Acid bis 2 ethylhexyl amine systems
2012Co-Authors: Pietro Calandra, Vincenzo Turco Liveri, Andrea Mandanici, Mikolaj Pochylski, F AliottaAbstract:This work focuses on the dynamic phenomena emerging in self-assembled transient intermolecular networks formed when two different surfactants are mixed. In particular, the relaxation processes in liquid mixtures composed by bis(2-ethylhexyl)amine (BEEA) and Octanoic Acid (OA) in the whole composition range has been investigated by dielectric spectroscopy and Brillouin spectroscopy. A thorough analysis of all the experimental data consistently suggests that, mainly driven by Acid-base interactions arising when the two surfactants are mixed, supra-molecular aggregates formation causes the slowing down of molecular dynamics. This, in turn, reflects to longer-range relaxations. These changes have been found to be composition-dependent, involving strong departures of the mixture physico-chemical properties from an ideal behaviour, and reflecting the structural and dynamical features of local structures. In particular, the peculiar dynamic processes occurring in these local inter-molecular structures, have been found to be the factors responsible for the observed and quite surprising increase of direct-current conductivity which occurs when two different (and pretty non-conductive) surfactants are mixed. The discovery can be used not only to design novel materials for application purposes but also to shed more light on the basic principles regulating charge migration in structured liquid systems.
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self assembly in surfactant based liquid mixtures Octanoic Acid bis 2 ethylhexyl amine systems
2012Co-Authors: Pietro Calandra, Vincenzo Turco Liveri, Pietro Riello, Isidora Freris, Andrea MandaniciAbstract:Abstract The physico-chemical properties of Bis(2-ethylhexyl)amine (BEEA) plus Octanoic Acid (OA) mixtures have been investigated by IR, SAXS, WAXS, viscosimetry, and AC complex impedance spectroscopy in the whole composition range. Mainly driven by proton transfer from the Acidic OA to the basic BEEA, the formation of stoichiometrically well-defined adducts takes place in the mixtures. This causes the slowing down of molecular dynamics and the increase in charge carrier number density. Interestingly, while the pure components possess no significant conductivity (about 10−12 S cm−1 at 25 °C), their mixtures show a composition-dependent enhanced conductivity (up to about 10−5 S cm−1), i.e., more than seven orders of magnitude higher than that of the pure components. The comparison of the composition dependence of viscosity, direct-current conductivity, and static permittivity indicates the concurrence of contributions of different adducts and that the dynamics controlling molecular reorientation and momentum and charge transfer, even if ultimately related to the proton transfer from OA to BEEA, are different. The results can be used not only to design novel materials for application purposes, but also to shed more light on the principles regulating molecular self-assembly in surfactant-based liquid systems.
Gaston Vantrappen - One of the best experts on this subject based on the ideXlab platform.
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c Octanoic Acid breath test to measure gastric emptying rate of solids
1994Co-Authors: Bart Maes, Martin Hiele, Paul Rutgeerts, Yvo Ghoos, Benny Geypens, Gaston VantrappenAbstract:We have developed a breath test to measure solid gastric emptying using a standardized scrambled egg test meal (250 kcal) labeled with [14C]Octanoic Acid or [13C]Octanoic Acid. In vitro incubation studies showed that Octanoic Acid is a reliable marker of the solid phase. The breath test was validated in 36 subjects by simultaneous radioscintigraphic and breath test measurements. Nine healthy volunteers were studied after intravenous administration of 200 mg erythromycin and peroral administration of 30 mg propantheline, respectively. Erythromycin significantly enhanced gastric emptying, while propantheline significantly reduced gastric emptying rates. We conclude that the [*C]Octanoic breath test is a promising and reliable test for measuring the gastric emptying rate of solids.
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pharmacological modulation of gastric emptying rate of solids as measured by the carbon labelled Octanoic Acid breath test influence of erythromycin and propantheline
1994Co-Authors: Bart Maes, Martin Hiele, Paul Rutgeerts, Yvo Ghoos, Benny Geypens, Gaston VantrappenAbstract:The *C (13C or 14C) labelled Octanoic Acid breath test was recently developed to measure the gastric emptying rate of solids. This study aimed to investigate whether it is sensitive enough to detect pharmacologically induced changes in the gastric emptying rate. Nine healthy volunteers were studied in basal condition, after intravenous administration of 200 mg erythromycin, and after peroral administration of 30 mg propantheline. Erythromycin significantly enhanced gastric emptying in all subjects, with an increase of the gastric emptying coefficient (p = 0.0043) in eight of nine and a fall in both the gastric half emptying time (p = 0.0020) and the lag phase (p = 0.0044) in all nine. Propantheline significantly reduced the gastric emptying rate, with a decreased gastric emptying coefficient (p = 0.0007) and an increased gastric half emptying time (p = 0.0168) in all subjects, but no change in the lag phase (p = 0.1214). Further mathematical analysis showed that breath sampling at 15 minutes intervals over a four hour period is recommended to guarantee accuracy and the discriminative value of the breath test in various gastric emptying patterns. In conclusion the *C labelled Octanoic Acid breath test is sufficiently sensitive to show pharmacologically induced changes of gastric emptying rates of solids.
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measurement of gastric emptying rate of solids by means of a carbon labeled Octanoic Acid breath test
1993Co-Authors: Yvo Ghoos, Martin Hiele, Bart Maes, Paul Rutgeerts, Benny Geypens, Gaston VantrappenAbstract:Abstract Background: The aim of the present study was to develop a breath test for measuring gastric emptying rate of solids that would induce less radiation exposure than radioscintigraphy and would be applicable to field testing. Methods: A test meal was used in which [ 14 C]-Octanoic Acid was mixed with egg yolk and prepared as a scrambled egg. The test meal was labeled with a second marker, 99m Tc-albumin colloid, and simultaneous radioscintigraphic and breath test measurements were performed in 36 subjects, 16 normal controls, and 20 patients with dyspeptic symptoms. Mathematical analysis of the excretion rate of labeled CO 2 resulted in the definition of three parameters, i.e., gastric emptying coefficient, gastric half-emptying time, and lag phase. Results: There was an excellent correlation between the gastric emptying coefficient and the scintigraphic half-emptying time ( r = −0.88); between the half-emptying time determined by the breath test and the scintigraphic half-emptying time ( r = 0.89); and between the lag phases determined by scintigraphy and those determined by breath test ( r = 0.92). 14 C can be replaced by 13 C for labeling the Octanoic Acid used in the breath test. Conclusions: It is concluded that the Octanoic Acid breath test is a reliable noninvasive test to measure gastric emptying rate of solids.
Bart Maes - One of the best experts on this subject based on the ideXlab platform.
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gastric emptying flow curves separated from carbon labeled Octanoic Acid breath test results
1998Co-Authors: Bart Maes, Yvo Ghoos, Benny Geypens, G Mys, Pieter Evenepoel, Paul RutgeertsAbstract:Recently, we developed the [13/14C]Octanoic Acid breath test to measure gastric emptying of solids. Although the method has been validated extensively, absorption, metabolism, and excretion of the ...
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the 13c Octanoic Acid breath test a noninvasive technique to assess gastric emptying in preterm infants
1996Co-Authors: G Veeremanwauters, Bart Maes, Yvo Ghoos, Hugo Devlieger, S Van Der Schoor, N Hebbalkar, Ephrem EggermontAbstract:SummaryGastric emptying (GE) is difficult to evaluate properly in preterm infants because of the lack of safe and reliable noninvasive methods. The 13C-Octanoic Acid breath test, a noninvasive method to assess GE, was validated in adults. The aim of this study was to adapt the methodology of the 13C
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c Octanoic Acid breath test to measure gastric emptying rate of solids
1994Co-Authors: Bart Maes, Martin Hiele, Paul Rutgeerts, Yvo Ghoos, Benny Geypens, Gaston VantrappenAbstract:We have developed a breath test to measure solid gastric emptying using a standardized scrambled egg test meal (250 kcal) labeled with [14C]Octanoic Acid or [13C]Octanoic Acid. In vitro incubation studies showed that Octanoic Acid is a reliable marker of the solid phase. The breath test was validated in 36 subjects by simultaneous radioscintigraphic and breath test measurements. Nine healthy volunteers were studied after intravenous administration of 200 mg erythromycin and peroral administration of 30 mg propantheline, respectively. Erythromycin significantly enhanced gastric emptying, while propantheline significantly reduced gastric emptying rates. We conclude that the [*C]Octanoic breath test is a promising and reliable test for measuring the gastric emptying rate of solids.
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pharmacological modulation of gastric emptying rate of solids as measured by the carbon labelled Octanoic Acid breath test influence of erythromycin and propantheline
1994Co-Authors: Bart Maes, Martin Hiele, Paul Rutgeerts, Yvo Ghoos, Benny Geypens, Gaston VantrappenAbstract:The *C (13C or 14C) labelled Octanoic Acid breath test was recently developed to measure the gastric emptying rate of solids. This study aimed to investigate whether it is sensitive enough to detect pharmacologically induced changes in the gastric emptying rate. Nine healthy volunteers were studied in basal condition, after intravenous administration of 200 mg erythromycin, and after peroral administration of 30 mg propantheline. Erythromycin significantly enhanced gastric emptying in all subjects, with an increase of the gastric emptying coefficient (p = 0.0043) in eight of nine and a fall in both the gastric half emptying time (p = 0.0020) and the lag phase (p = 0.0044) in all nine. Propantheline significantly reduced the gastric emptying rate, with a decreased gastric emptying coefficient (p = 0.0007) and an increased gastric half emptying time (p = 0.0168) in all subjects, but no change in the lag phase (p = 0.1214). Further mathematical analysis showed that breath sampling at 15 minutes intervals over a four hour period is recommended to guarantee accuracy and the discriminative value of the breath test in various gastric emptying patterns. In conclusion the *C labelled Octanoic Acid breath test is sufficiently sensitive to show pharmacologically induced changes of gastric emptying rates of solids.
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measurement of gastric emptying rate of solids by means of a carbon labeled Octanoic Acid breath test
1993Co-Authors: Yvo Ghoos, Martin Hiele, Bart Maes, Paul Rutgeerts, Benny Geypens, Gaston VantrappenAbstract:Abstract Background: The aim of the present study was to develop a breath test for measuring gastric emptying rate of solids that would induce less radiation exposure than radioscintigraphy and would be applicable to field testing. Methods: A test meal was used in which [ 14 C]-Octanoic Acid was mixed with egg yolk and prepared as a scrambled egg. The test meal was labeled with a second marker, 99m Tc-albumin colloid, and simultaneous radioscintigraphic and breath test measurements were performed in 36 subjects, 16 normal controls, and 20 patients with dyspeptic symptoms. Mathematical analysis of the excretion rate of labeled CO 2 resulted in the definition of three parameters, i.e., gastric emptying coefficient, gastric half-emptying time, and lag phase. Results: There was an excellent correlation between the gastric emptying coefficient and the scintigraphic half-emptying time ( r = −0.88); between the half-emptying time determined by the breath test and the scintigraphic half-emptying time ( r = 0.89); and between the lag phases determined by scintigraphy and those determined by breath test ( r = 0.92). 14 C can be replaced by 13 C for labeling the Octanoic Acid used in the breath test. Conclusions: It is concluded that the Octanoic Acid breath test is a reliable noninvasive test to measure gastric emptying rate of solids.
Pietro Calandra - One of the best experts on this subject based on the ideXlab platform.
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anti arrhenian behaviour of conductivity in Octanoic Acid bis 2 ethylhexyl amine systems a physico chemical study
2015Co-Authors: Pietro Calandra, Vincenzo Turco Liveri, Angela Ruggirello, Mariano Licciardi, Domenico Lombardo, Andrea MandaniciAbstract:Pure surfactant liquids and their binary mixtures, owing to the amphiphilic nature of the molecules involved, can exhibit nano-segregation and peculiar transport properties. The structural and dynamic properties of Octanoic Acid (OA)–bis(2-ethylhexyl)amine (BEEA) liquid mixtures at various compositions have been studied by Wide Angle X-ray Scattering (WAXS), 1H-NMR and broadband dielectric spectroscopy as a function of temperature. It was found that the self-assembly occurs via proton exchange between the OA COOH group and the BEEA NH one; such self-assembled local structures are affected anisotropically by a temperature increase so that the thermal dilatation is more marked in a direction perpendicular to the molecular axis whereas it is practically unaffected along its axis. Interestingly, an anti-Arrhenian behaviour of the conductivity has been found at the OA molar ratio (XOA) of around 0.66. This behaviour has been interpreted as the overall result of the competition between the tendency of OA surfactant molecules to aggregate through OA–OA H-bond formation and the establishment of hetero-adducts OA–BEEA joined to the temperature disordering effect. The potentialities of such systems as proton conducting water-free organic-based liquid systems enable them to be tailored for their direct use as liquid membranes in fuel cells but also, from a more general perspective, for the piloted design of smart materials for specific applications.
-
emerging dynamics in surfactant based liquid mixtures Octanoic Acid bis 2 ethylhexyl amine systems
2012Co-Authors: Pietro Calandra, Vincenzo Turco Liveri, Andrea Mandanici, Mikolaj Pochylski, F AliottaAbstract:This work focuses on the dynamic phenomena emerging in self-assembled transient intermolecular networks formed when two different surfactants are mixed. In particular, the relaxation processes in liquid mixtures composed by bis(2-ethylhexyl)amine (BEEA) and Octanoic Acid (OA) in the whole composition range has been investigated by dielectric spectroscopy and Brillouin spectroscopy. A thorough analysis of all the experimental data consistently suggests that, mainly driven by Acid-base interactions arising when the two surfactants are mixed, supra-molecular aggregates formation causes the slowing down of molecular dynamics. This, in turn, reflects to longer-range relaxations. These changes have been found to be composition-dependent, involving strong departures of the mixture physico-chemical properties from an ideal behaviour, and reflecting the structural and dynamical features of local structures. In particular, the peculiar dynamic processes occurring in these local inter-molecular structures, have been found to be the factors responsible for the observed and quite surprising increase of direct-current conductivity which occurs when two different (and pretty non-conductive) surfactants are mixed. The discovery can be used not only to design novel materials for application purposes but also to shed more light on the basic principles regulating charge migration in structured liquid systems.
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self assembly in surfactant based liquid mixtures Octanoic Acid bis 2 ethylhexyl amine systems
2012Co-Authors: Pietro Calandra, Vincenzo Turco Liveri, Pietro Riello, Isidora Freris, Andrea MandaniciAbstract:Abstract The physico-chemical properties of Bis(2-ethylhexyl)amine (BEEA) plus Octanoic Acid (OA) mixtures have been investigated by IR, SAXS, WAXS, viscosimetry, and AC complex impedance spectroscopy in the whole composition range. Mainly driven by proton transfer from the Acidic OA to the basic BEEA, the formation of stoichiometrically well-defined adducts takes place in the mixtures. This causes the slowing down of molecular dynamics and the increase in charge carrier number density. Interestingly, while the pure components possess no significant conductivity (about 10−12 S cm−1 at 25 °C), their mixtures show a composition-dependent enhanced conductivity (up to about 10−5 S cm−1), i.e., more than seven orders of magnitude higher than that of the pure components. The comparison of the composition dependence of viscosity, direct-current conductivity, and static permittivity indicates the concurrence of contributions of different adducts and that the dynamics controlling molecular reorientation and momentum and charge transfer, even if ultimately related to the proton transfer from OA to BEEA, are different. The results can be used not only to design novel materials for application purposes, but also to shed more light on the principles regulating molecular self-assembly in surfactant-based liquid systems.
