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Rapid Communications in Mass... 2004It has been proposed that the (13)C-octanoic acid breath test (OBT) provides a safe, non-radioactive means of measuring gastric emptying. However, deuterated octanoic... (Comparative Study)
Comparative Study
It has been proposed that the (13)C-octanoic acid breath test (OBT) provides a safe, non-radioactive means of measuring gastric emptying. However, deuterated octanoic acid provides a better marker when compared with scintigraphy, as the kinetics are less complex than those of the (13)C label. The appearance of (2)H in saliva is modelled as a two-compartment body water system, using an asymmetric triangular gastric emptying function. This study compared the (2)H-octanoic acid saliva test (OST) with the OBT in measuring altered states of gastric emptying in the nutritional context of diet manipulation. Gastric emptying was measured using the OST and OBT in a three-way crossover study involving 12 healthy male and female subjects (mean BMI = 23.4 kg/m(2), aged 24-57 years). Following an overnight fast, subjects were given an egg meal, labelled with 10 microL/kg body weight (2)H-octanoic acid and 100 microL (13)C-octanoic acid. The meal was nutritionally manipulated to provide a 1 MJ, 2 MJ or 3 MJ meal. Breath and saliva samples were collected at regular intervals for 6 h, with further saliva samples being collected over four subsequent days. (2)H isotopic enrichment in saliva and (13)C isotopic enrichment in breath were analysed using isotope ratio mass spectrometry and the data fitted to the respective gastric emptying models. The half excretion time (T(1/2) (D)), time to maximum emptying rate (T(1) (D)) and time when emptying is complete (T(2) (D)) were calculated from the (2)H saliva test data, and the lag time (T(lag) (C)), half excretion time (T(1/2) (C)), latency phase (T(lat) (C)) and ascension time (T(asc) (C)) were calculated from the (13)C breath test data. Overall, the OBT correlated well with the OST, with a significant relationship between T(1/2) (C) and T(1/2) (D), a significant relationship between T(lat) (C) and T(1) (D) and finally a significant relationship between T(asc) (C) and T(2) (D). Gastric emptying measured using the OST was significantly faster with the 1 MJ meal (DeltaT(1/2) (D) = -0.77 h vs. 2 MJ, p = 0.004). Increases were also seen when the meal size was increased from 2 MJ to 3 MJ (DeltaT(1/2) (D) = +0.44 h vs. 2 MJ), but these were not significant. These trends were mirrored in the OBT data, with significant differences between 1 MJ and 2 MJ (DeltaT(1/2) (C) = -0.63 h vs. 2 MJ, p = 0.013) and non-significant increases with the larger 3 MJ meal (DeltaT(1/2) (C) = +0.10 h vs. 2 MJ). Total meal calorie content was shown to have an effect on gastric emptying using both the OBT and the OST. The deuterium method allows the direct calculation of the gastric emptying function and could be used as an alternative to gamma scintigraphy, allowing further validation of the (13)C-octanoic acid breath test.
Topics: Adult; Breath Tests; Caprylates; Carbon Isotopes; Cross-Over Studies; Deuterium; Eating; Female; Gastric Emptying; Humans; Male; Mass Spectrometry; Middle Aged; Saliva
PubMed: 15150821
DOI: 10.1002/rcm.1440 -
Clinical Neurophysiology : Official... Jul 2018To investigate the effect of octanoic acid (OA) on the peripheral component of tremor, as well as OA's differential effects on the central and peripheral tremor... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To investigate the effect of octanoic acid (OA) on the peripheral component of tremor, as well as OA's differential effects on the central and peripheral tremor component in essential tremor (ET) patients.
METHODS
We analyzed postural tremor accelerometry data from a double-blind placebo-controlled cross-over study evaluating the effect of 4 mg/kg OA in ET. The weighted condition was used to identify tremor power for both the central and peripheral tremor components. Exploratory non-parametric statistical analyses were used to describe the relation between the central and peripheral component of tremor power.
RESULTS
A peripheral tremor component was identified in 4 out of 18 subjects. Tremor power was reduced after OA administration in both the central and the peripheral tremor component. There was a positive correlation of tremor power between the central and peripheral component, both after placebo and OA.
CONCLUSIONS
When present, the peripheral component was closely related to the central tremor component. We hypothesize that the magnitude of the peripheral mechanical component of tremor is determined by that of the central component.
SIGNIFICANCE
Both central and peripheral component of tremor are reduced after OA, with the central component providing the energy driving the peripheral component.
Topics: Adult; Caprylates; Cross-Over Studies; Double-Blind Method; Electromyography; Essential Tremor; Female; Humans; Male; Treatment Outcome
PubMed: 29678370
DOI: 10.1016/j.clinph.2018.03.016 -
Journal of General Microbiology Mar 1991Plasma membrane ATPase activity of Saccharomyces cerevisiae IGC 3507III grown in the presence of the lipophilic acid octanoic acid [4-50 mg l-1 (0.03-0.35 mM), pH 4.0]...
Plasma membrane ATPase activity of Saccharomyces cerevisiae IGC 3507III grown in the presence of the lipophilic acid octanoic acid [4-50 mg l-1 (0.03-0.35 mM), pH 4.0] was 1.5-fold higher than that in cells grown in its absence. The Km for ATP, the pH profile and the sensitivity to orthovanadate of the basal and the activated forms of the membrane ATPase were identical. This activation was closely associated with a decrease in the biomass yield and an increase in the ethanol yield, and was rapidly reversed in vivo after removal of the acid. However, the activated level was preserved when membranes were extracted and subjected to manipulations which eliminated or decreased octanoic acid incorporation in the plasma membrane. The activity of the basal plasma membrane ATPase in the total membrane fraction was slightly increased by incubation at pH 6.5 with octanoic acid at 100 mg l-1 or less (2.4 mg acid form plus 97.6 mg octanoate ion l-1). However, destruction of the permeability barrier between the enzyme and its substrate could not explain the in vivo activation. A role for plasma membrane ATPase activation in the regulation of the intracellular pH (pHi) of cells grown with octanoic acid was not proven.
Topics: Adenosine Triphosphatases; Caprylates; Cell Membrane; Enzyme Activation; Ethanol; Hydrogen-Ion Concentration; Kinetics; Saccharomyces cerevisiae; Vanadates
PubMed: 1827836
DOI: 10.1099/00221287-137-3-645 -
The American Journal of Gastroenterology Jan 1998The accuracy of the 13C-octanoic acid breath test is enhanced by breath sampling over 6 h rather than 4 h, but this increases the cost of the test. Our aim was to... (Comparative Study)
Comparative Study
OBJECTIVE
The accuracy of the 13C-octanoic acid breath test is enhanced by breath sampling over 6 h rather than 4 h, but this increases the cost of the test. Our aim was to validate a less costly but accurate sequence of breath sampling for measuring gastric emptying of solids.
METHODS
We performed the 13C-octanoic acid breath test and tested its reproducibility relative to simultaneous scintigraphy in 30 healthy volunteers.
RESULTS
There was a significant but weak correlation between t1/2 measured by the two tests (rs = 0.54, p < 0.005), but not between the duration of the lag phase. The differences in the t1/2 measurements between the tests were different between subjects but were highly reproducible within subjects. Within- and between-subject variations of measurements of gastric emptying with the 13C-octanoic acid breath test were not significantly different from the variations observed with scintigraphy. A subset of 11 breath samples collected over 6 h (24 samples) predicted (r2 > 0.95) the variables characterizing the cumulative appearance of 13CO2 in breath; these samples were at 35, 50, 95, 110, 140, 155, 215, 245, 260, 290, and 335 min. The accuracy of this subset of sampling times was confirmed in a separate set of breath test samples over 6 h from the same 30 subjects.
CONCLUSIONS
The 13C-octanoic acid breath test for gastric emptying of solids is as reproducible as scintigraphy. A subset of 11 sampling times provides sufficient information to characterize the whole breath-test curve, but the sampling period should be extended to 6 h after dosing.
Topics: Adolescent; Adult; Aged; Breath Tests; Caprylates; Carbon Isotopes; Chromatography, Gas; Female; Gastric Emptying; Humans; Linear Models; Male; Middle Aged; Models, Biological; Predictive Value of Tests; Radionuclide Imaging; Reproducibility of Results; Stomach
PubMed: 9448183
DOI: 10.1111/j.1572-0241.1998.092_c.x -
The Journal of Biological Chemistry Nov 2001We have identified the amphibian ghrelin from the stomach of the bullfrog. We also examined growth hormone (GH)-releasing activity of this novel peptide in both the rat...
We have identified the amphibian ghrelin from the stomach of the bullfrog. We also examined growth hormone (GH)-releasing activity of this novel peptide in both the rat and bullfrog. The three forms of ghrelin identified, each comprised of 27 or 28 amino acids, possessed 29% sequence identity to the mammalian ghrelins. A unique threonine at amino acid position 3 (Thr(3)) in bullfrog ghrelin differs from the serine present in the mammalian ghrelins; this Thr(3) is acylated by either n-octanoic or n-decanoic acid. The frog ghrelin-28 has a complete structure of GLT (O-n-octanoyl)FLSPADMQKIAERQSQNKLRHGNM; the structure of frog ghrelin-27 was determined to be GLT(O-n-octanoyl)FLSPADMQKIAERQSQNKLRHGN; frog ghelin-27-C10 possessed a structure of GLT(O-n-decanoyl)FLSPADMQKIAERQSQNKLRHGN. Northern blot analysis demonstrated that ghrelin mRNA is predominantly expressed in the stomach. Low levels of gene expression were observed in the heart, lung, small intestine, gall bladder, pancreas, and testes, as revealed by reverse transcription polymerase chain reaction analysis. Bullfrog ghrelin stimulated the secretion of both GH and prolactin in dispersed bullfrog pituitary cells with potency 2-3 orders of magnitude greater than that of rat ghrelin. Bullfrog ghrelin, however, was only minimally effective in elevating plasma GH levels following intravenous injection into rats. These results indicate that although the regulatory mechanism of ghrelin to induce GH secretion is evolutionary conserved, the structural changes in the different ghrelins result in species-specific receptor binding.
Topics: Amino Acid Sequence; Animals; Base Sequence; Caprylates; Chromatography, High Pressure Liquid; DNA, Complementary; Ghrelin; Molecular Sequence Data; Peptide Hormones; Peptides; Rana catesbeiana; Sequence Homology, Amino Acid; Stomach; Threonine
PubMed: 11546772
DOI: 10.1074/jbc.M105212200 -
Digestive and Liver Disease : Official... Aug 2010Standardization of the (13)C-octanoic acid breath test is still lacking.
BACKGROUND
Standardization of the (13)C-octanoic acid breath test is still lacking.
AIM
To evaluate the accuracy of the (13)C-octanoic acid breath test using a new standardized ready-to-eat, gluten-, glucose-, and lactose-free muffin.
METHODS
Healthy subjects were recruited and sorted by sex and age. Patients with diabetic gastroparesis and untreated celiac disease with known gastric motility disorders were also tested with the new labelled muffin. Expired breath (13)CO(2) was analysed and t(1/2) was calculated.
RESULTS
Overall, 131 healthy subjects were enrolled. The reference range of t(1/2) was 88+/-29min with the value of 146min as the upper limit of normal range. No significant difference in t(1/2) was found among subjects sorted by sex or age. The within-subject variability of t(1/2) was 17%. Mean (+/-standard deviation) t(1/2) values were 179+/-50min in patients with diabetic gastroparesis (n=8) and 151+/-20min in those with untreated celiac disease (n=11) (p
CONCLUSIONS
A new standardized test meal simplifies the execution of the (13)C-octanoic acid breath test, is not influenced by sex or age, has low intra-individual variability, is palatable, does not cause side effects, and is able to evaluate gastric emptying in both patients and healthy controls. Moreover, it can be used in subjects with lactose intolerance, diabetes, and celiac disease.
Topics: Adult; Breath Tests; Caprylates; Carbon Isotopes; Celiac Disease; Diabetic Neuropathies; Diagnostic Techniques, Digestive System; Eating; Female; Food; Gastric Emptying; Gastroparesis; Humans; Male; Middle Aged
PubMed: 20116352
DOI: 10.1016/j.dld.2010.01.001 -
Metabolism: Clinical and Experimental Oct 1994A large number of very-low-birth weight infants are fed formulas containing medium-chain triglycerides (MCT) to enhance fat and calcium absorption. Studies are available... (Clinical Trial)
Clinical Trial
A large number of very-low-birth weight infants are fed formulas containing medium-chain triglycerides (MCT) to enhance fat and calcium absorption. Studies are available on the intestinal absorption of MCT, which is nearly complete, but uncertainties exist on the metabolic fate of octanoic acid, the major component of MCT. Oxidation accounts for approximately 50% of the dietary intake, and losses as dicarboxylic acids in the urine are negligible. Since storage in adipose tissue is limited, conversion into long-chain fatty acids (LCFA) is likely to be an important route. To study the nonoxidative metabolism of MCT, six preterm infants fed a standard premature formula containing 38 weight% (wt%) MCT (54 mol% medium-chain fatty acids (MCFA), of which 35 mol% is octanoic acid) were studied at 4 weeks of age, when on full oral intake and receiving on average 130 kcal/kg/d. The study consisted of an oral primed constant-rate infusion of [13C]-octanoate and the measurement of the 13C enrichment of individual fatty acids in plasma triglycerides (TG) by a highly sensitive on-line combustion method using gas chromatography-isotope ratio mass spectrometry (GC-IRMS). We observed a significant incorporation of the dietary [13C]-octanoic acid in plasma TG (10.0% +/- 4.5% of the enrichment of the diet). A noticeable incorporation of the label was detected in myristic and palmitic acids (4.6% +/- 2.5% and 7.8% +/- 4.1% of the octanoic enrichment of the diet). The absolute amount of the fatty acids was studied with conventional GC, and the plasma TG fatty acid profile differed markedly from the diet.(ABSTRACT TRUNCATED AT 250 WORDS)
Topics: Caprylates; Fatty Acids; Gas Chromatography-Mass Spectrometry; Humans; Infant Food; Infant, Newborn; Infant, Premature; Isotope Labeling; Triglycerides
PubMed: 7934982
DOI: 10.1016/0026-0495(94)90224-0 -
Fertility and Sterility Aug 2013To screen human serum albumin (HSA) preparations for toxicity and investigate causes of variation.
OBJECTIVE
To screen human serum albumin (HSA) preparations for toxicity and investigate causes of variation.
DESIGN
Experimental laboratory study.
SETTING
University-based laboratory.
ANIMAL(S)
FVB and CF1 mice crossed to create embryos used in experiments.
INTERVENTION(S)
Mouse embryo assay performed with 5% or 15% HSA (100 mg/mL albumin) from three samples from three separate manufacturers (A, B, C).
MAIN OUTCOME MEASURE(S)
Blastocyst rates calculated at 96 hours of culture (experiments repeated in triplicate).
RESULT(S)
The HSA preparations were desalted to remove stabilizers added during HSA processing, then mass spectrometry was used to determine the relative variation in stabilizer concentrations; the effect of the stabilizer octanoic acid on embryo development was tested. At 5% HSA, all samples had blastocyst rates ≥ 70%; at 15% HSA, the blastocyst rates for samples B and C were <50%. Desalting did not affect sample B but did improve the blastocyst rates of sample C. Mass spectrometry revealed high levels of octanoic acid in sample C compared with sample A. The addition of octanoic acid to sample A produced toxicity similar to sample C.
CONCLUSION(S)
The stabilizer octanoic acid varies by lot and inhibits embryo development. Because octanoic acid is known to cause disruptions in mitochondrial bioenergetics, reduce intracellular pH, and induce oxidative damage in peripheral tissues, its use in embryo culture should be monitored and limited.
Topics: Animals; Caprylates; Culture Media; Dose-Response Relationship, Drug; Drug Stability; Embryo Culture Techniques; Embryo, Mammalian; Excipients; Female; Humans; Mice; Quality Control; Salts; Serum Albumin
PubMed: 23602317
DOI: 10.1016/j.fertnstert.2013.03.034 -
Cor Et Vasa 1989The aim of the study was to clarify the role of octanoic acid (OA) in the development of cardiovascular disorders occurring in some liver diseases associated with high...
The aim of the study was to clarify the role of octanoic acid (OA) in the development of cardiovascular disorders occurring in some liver diseases associated with high OA levels in blood serum. The effect of OA (caprylic acid) on the functional state of the cardiovascular system was studied in guinea pig by means of the thermodilution method and ultrasound Doppler echography. It was found that, as a result of its inotropic action, OA decreases arterial pressure and vascular resistance while increasing cardiac output. The effect of OA can be inhibited by the administration of indomethacin, a fact suggesting the prostaglandin system plays a role in the mechanism of cardiovascular action of OA. This hypothesis represents a new concept regarding the pathogenesis of the hyperdynamic cardiovascular syndrome in liver cirrhosis and hepatic encephalopathy.
Topics: Animals; Antihypertensive Agents; Blood Pressure; Caprylates; Cardiac Output; Cardiovascular Diseases; Cardiovascular System; Dinoprostone; Guinea Pigs; Hepatic Encephalopathy; Humans; Indomethacin; Liver Cirrhosis; Male; Syndrome; Vascular Resistance
PubMed: 2805707
DOI: No ID Found -
Science Advances Mar 2023Ongoing climate change is driving the search for renewable and carbon-neutral alternatives to fossil fuels. Photocatalytic conversion of fatty acids to hydrocarbons by...
Ongoing climate change is driving the search for renewable and carbon-neutral alternatives to fossil fuels. Photocatalytic conversion of fatty acids to hydrocarbons by fatty acid photodecarboxylase (FAP) represents a promising route to green fuels. However, the alleged low activity of FAP on C2 to C12 fatty acids seemed to preclude the use for synthesis of gasoline-range hydrocarbons. Here, we reveal that FAP (FAP) can convert -octanoic acid in vitro four times faster than -hexadecanoic acid, its best substrate reported to date. In vivo, this translates into a FAP-based production rate over 10-fold higher for -heptane than for -pentadecane. Time-resolved spectroscopy and molecular modeling demonstrate that FAP's high catalytic activity on -octanoic acid is, in part, due to an autocatalytic effect of its -heptane product, which fills the rest of the binding pocket. These results represent an important step toward a bio-based and light-driven production of gasoline-like hydrocarbons.
Topics: Fatty Acids; Caprylates; Gasoline; Chlorella; Hydrocarbons
PubMed: 37000872
DOI: 10.1126/sciadv.adg3881