RESUMEN
Carbohydrate malabsorption and subsequent gastrointestinal symptoms are a common clinical problem in pediatrics. Hydrogen (H2) and methane (CH4) breath tests are a cheap and non-invasive procedure for diagnosing fructose and lactose malabsorption (FM/LM) but test accuracy and reliability as well as the impact of non-hydrogen producers (NHP) is unclear. CH4 breath tests (MBT), blood sugar tests (BST) and clinical symptoms were compared with H2 breath tests (HBT) for FM/LM. 187/82 tests were performed in children (2 to 18 years) with unclear chronic/recurrent abdominal pain and suspected FM/LM. In FM and LM, we found a significant correlation between HBT and MBT/BST. In LM, MBT differentiated most of the patients correctly and BST might be used as an exclusion test. However, additional MBT and BST had no diagnostic advantage in FM. NHP still remain a group of patients, which cannot be identified using the recommended CH4 cut-off values in FM or LM. Reported symptoms during breath tests are not a reliable method to diagnose FM/LM. Overall a combined test approach might help in diagnosing children with suspected carbohydrate malabsorption.
Asunto(s)
Intolerancia a la Fructosa/diagnóstico , Hidrógeno/análisis , Intolerancia a la Lactosa/diagnóstico , Metano/análisis , Adolescente , Glucemia , Pruebas Respiratorias , Niño , Preescolar , Femenino , Intolerancia a la Fructosa/sangre , Humanos , Intolerancia a la Lactosa/sangre , Masculino , Reproducibilidad de los Resultados , Estudios RetrospectivosRESUMEN
A resistant starch (RS) mixture (MIX) consisting of fibre of potatoes (FP) and wrinkled pea starch (WPS), and high amylose maize starch (HAMS) were supplemented in adults to evaluate their effects on fat oxidation by means of a 13CO2-breath test. Sixteen subjects received a regular diet either without or with the supplementation of MIX and HAMS in randomised order. After administration of a [U-13C]algal lipid mixture, exhaled air was collected over 14â h in 0.5- and 1-h intervals. The 13C abundances were measured by nondispersive infrared spectroscopy. In comparison to the dry run (DR), supplementation with MIX and with HAMS increased the cumulative percentage dose recovery: (DR: 16.7â %, MIX: 16.9â %, HAMS: 18.0â %), but without statistical significance. The colonic degradation of MIX and HAMS to short-chain fatty acids tends to lower the formation of carbohydrate-derived acetyl-CoA and contributes to a postprandial lipid oxidation increase by using fat-derived acetyl-CoA as a compensatory fuel source.
Asunto(s)
Dióxido de Carbono/metabolismo , Dieta , Suplementos Dietéticos , Grasas/metabolismo , Almidón/metabolismo , Adolescente , Adulto , Amilosa/metabolismo , Pruebas Respiratorias , Isótopos de Carbono/análisis , Femenino , Humanos , Masculino , Persona de Mediana Edad , Oxidación-Reducción , Distribución Aleatoria , Adulto JovenRESUMEN
Three resistant starches (RSs), namely fibre of potatoes (FP), wrinkle pea starch (WPS), and high amylose maize starch (HAMS) with different dietary fibre contents, were supplemented in adults to evaluate their effects on urinary nitrogen and ammonia excretion as well as on faecal nitrogen excretion by means of lactose-[(15)N2]ureide ((15)N-LU) degradation. Twenty subjects received a regular diet either without or with the supplementation of FP, WPS, and HAMS in a randomized order. After administration of (15)N-LU, urine and faeces were collected over 48 and 72 h, respectively, whereas blood was collected after 6 h. The (15)N-abundances were measured by isotope ratio mass spectrometry. In comparison to the dry run, supplementation with RS significantly lowered renal (15)N-excretion (dry run: 43.2%, FP: 34.6%, WPS: 37.9%, HAMS: 36.4%) as well as the corresponding (15)NH3-excretion (dry run: 0.08%, FP: 0.06%, HAMS: 0.05%), clearly indicating a reduced colonic nitrogen generation at high dietary fibre intake.
Asunto(s)
Amoníaco/metabolismo , Carbohidratos de la Dieta/metabolismo , Pisum sativum/química , Solanum tuberosum/química , Zea mays/química , Adulto , Amoníaco/sangre , Amoníaco/orina , Colon/metabolismo , Carbohidratos de la Dieta/administración & dosificación , Fibras de la Dieta/administración & dosificación , Fibras de la Dieta/metabolismo , Suplementos Dietéticos/análisis , Heces/química , Femenino , Humanos , Lactosa/análisis , Lactosa/sangre , Lactosa/orina , Masculino , Nitrógeno/sangre , Nitrógeno/metabolismo , Nitrógeno/orina , Isótopos de Nitrógeno/análisis , Isótopos de Nitrógeno/sangre , Isótopos de Nitrógeno/orina , Urea/análogos & derivados , Urea/análisis , Urea/sangre , Urea/orina , Adulto JovenRESUMEN
INTRODUCTION: ColoPulse tablets are an innovative development in the field of oral dosage forms characterized by a distal ileum and colon-specific release. Previous studies in humans showed release in the ileo-colonic region, but the relationship between gastrointestinal pH and release was not experimentally proven in vivo. This information will complete the in vivo release-profile of ColoPulse tablets. MATERIALS AND METHODS: Release from ColoPulse tablets was studied in 16 healthy volunteers using the dual label isotope strategy. To determine gastrointestinal pH profiles and transit times the IntelliCap system was used. A ColoPulse tablet containing 13C-urea and an uncoated, immediate release tablet containing 15N2-urea were taken simultaneously followed by a standardized breakfast after three hours. Five minutes after intake of the tablets the IntelliCap capsule was swallowed and pH was measured until excretion in the feces. Breath and urine samples were collected for isotope analysis. RESULTS: Full analysis could be performed in 12 subjects. Median bioavailability of 13C -urea was 82% (95% CI 74-94%, range 61-114%). The median lag time (5% release of 13C) was 5:42 h (95% CI 5:18-6:18 h, range 2:36-6:36 h,) There was no statistically significant difference between lag time based on isotope signal and colon arrival time (CAT) based on pH (median 5:42 vs 5:31 h p = 0.903). In all subjects an intestinal pH value of 7.0 was reached before release of 13C from the ColoPulse tablet occurred. DISCUSSION AND CONCLUSIONS: From the combined data from the IntelliCap system and the 13C -isotope signal it can be concluded that release from a ColoPulse tablet in vivo is not related to transit times but occurs in the ileo-colonic region after pH 7.0 is reached. This supports our earlier findings and confirms that the ColoPulse system is a promising delivery system for targeting the distal ileum and colon. TRIAL REGISTRATION: ISRCTN Registry 18301880.
Asunto(s)
Colon/química , Colon/metabolismo , Portadores de Fármacos/farmacocinética , Voluntarios Sanos , Íleon/química , Íleon/metabolismo , Administración Oral , Adolescente , Adulto , Anciano , Disponibilidad Biológica , Portadores de Fármacos/administración & dosificación , Portadores de Fármacos/química , Liberación de Fármacos , Femenino , Tránsito Gastrointestinal , Humanos , Concentración de Iones de Hidrógeno , Cinética , Masculino , Persona de Mediana Edad , Especificidad de Órganos , Comprimidos , Adulto JovenRESUMEN
This paper describes various methodological aspects that were encountered during the development of a system to monitor the in vivo behaviour of a newly developed colon delivery device that enables oral drug treatment of inflammatory bowel diseases. [(13)C]urea was chosen as the marker substance. Release of [(13)C]urea in the ileocolonic region is proven by the exhalation of (13)CO2 in breath due to bacterial fermentation of [(13)C]urea. The (13)CO2 exhalation kinetics allows the calculation of a lag time as marker for delay of release, a pulse time as marker for the speed of drug release and the fraction of the dose that is fermented. To determine the total bioavailability, also the fraction of the dose absorbed from the intestine must be quantified. Initially, this was done by calculating the time-dependent [(13)C]urea appearance in the body urea pool via measurement of (13)C abundance and concentration of plasma urea. Thereafter, a new methodology was successfully developed to obtain the bioavailability data by measurement of the urinary excretion rate of [(13)C]urea. These techniques required two experimental days, one to test the coated device, another to test the uncoated device to obtain reference values for the situation that 100 % of [(13)C]urea is absorbed. This is hampered by large day-to-day variations in urea metabolism. Finally, a completely non-invasive, one-day test was worked out based on a dual isotope approach applying a simultaneous administration of [(13)C]urea in a coated device and [(15)N2]urea in an uncoated device. All aspects of isotope-related analytical methodologies and required calculation and correction systems are described.
Asunto(s)
Colon/metabolismo , Sistemas de Liberación de Medicamentos , Urea/farmacocinética , Algoritmos , Pruebas Respiratorias , Dióxido de Carbono/metabolismo , Isótopos de Carbono/sangre , Isótopos de Carbono/farmacocinética , Isótopos de Carbono/orina , Humanos , Modelos Biológicos , Isótopos de Nitrógeno/sangre , Isótopos de Nitrógeno/farmacocinética , Isótopos de Nitrógeno/orina , Urea/sangre , Urea/orinaRESUMEN
Resistant starch (RS) and Lactobacillus acidophilus yoghurt (LC1) were supplemented simultaneously in healthy adults to evaluate the effect on the urinary and faecal nitrogen and ammonia excretion by means of lactose-[(15)N2]ureide ((15)N-LU) degradation. Nineteen subjects received a regular daily diet either without or with supplementation of an RS-LC1-mixture composed of fibre of potatoes (RS type 1), wrinkle pea starch (RS type 2), and LC1 over a 20-day period in randomised order. Thereafter, (15)N-LU was administered together with breakfast. Urine and faeces were collected over a period of 48 and 72 h, respectively. The (15)N abundances were measured by isotope ratio mass spectrometry. The intake of the pre- and probiotic mixture composed of RS of type 1, type 2 and of LC1 significantly lowered the colonic generation and the renal excretion of toxic (15)NH3 and functioned as an ammonia shift from urinary to faecal (15)N excretion when using (15)N-LU as a xenobiotic marker.
Asunto(s)
Amoníaco/orina , Lactosa/farmacocinética , Nitrógeno/metabolismo , Prebióticos , Probióticos/farmacocinética , Almidón/farmacocinética , Urea/análogos & derivados , Yogur , Adulto , Estudios Cruzados , Heces/química , Femenino , Humanos , Riñón/metabolismo , Lactobacillus , Lactobacillus acidophilus , Masculino , Isótopos de Nitrógeno/farmacocinética , Isótopos de Nitrógeno/orina , Urea/farmacocinética , Adulto JovenRESUMEN
PURPOSE: Conventional bioavailability testing of dosage forms based on plasma concentration-time graphs of two products in a two-period, crossover-design, is not applicable to topical treatment of intestinal segments. We introduce an isotope dual-label approach ((13)C- and (15)N(2)-urea) for colon drug delivery systems that can be performed in a one-day, non-invasive study-design. METHODS: Four healthy volunteers took an uncoated or a ColoPulse-capsule containing (13)C-urea and an uncoated capsule containing (15)N(2)-urea. In case of colon-release (13)C-urea is fermented and (13)C detected as breath (13)CO(2). Absorbed (13)C-urea and (15)N-urea are detected in urine. RESULTS: C and (15)N in urine released from uncoated capsules showed a ratio of 1.01 ± 0.06. The (13)C/(15)N-recovery ratio after intake of a ColoPulse-capsule was constant and lower >12 h post-dose (median 0.22, range 0.13-0.48). The (13)C/(15)N-ratio in a single urine sample at t ≥ 12 h predicted the 24 h non-fermented fraction (13)C of <26 %. Breath (13)CO(2) indicated delayed (>3 h) release and a fermented fraction (13)C >54 %. CONCLUSIONS: Breath and urine (13)C and (15)N data describe the release-profile and local bioavailability of a colon delivery device. This allows non-invasive bioavailability studies for evaluation of colon-specific drug delivery systems without radioactive exposure and with increased power and strongly reduced costs.
Asunto(s)
Colon/metabolismo , Sistemas de Liberación de Medicamentos , Urea/administración & dosificación , Urea/farmacocinética , Adulto , Pruebas Respiratorias , Cápsulas , Isótopos de Carbono/análisis , Isótopos de Carbono/farmacocinética , Isótopos de Carbono/orina , Femenino , Humanos , Absorción Intestinal , Masculino , Persona de Mediana Edad , Modelos Biológicos , Isótopos de Nitrógeno/análisis , Isótopos de Nitrógeno/farmacocinética , Isótopos de Nitrógeno/orina , Proyectos de Investigación , Urea/orinaRESUMEN
Our research group of the Children's Hospital of the University of Rostock (Rostock group) has long-time experience in (15)N-labelling and in using yeast protein and its hydrolysates for tracer kinetic studies to evaluate parameters of the whole-body protein metabolism in premature infants. The particular advantage of applying an economically convenient, highly (15)N-enriched, and completely labelled yeast protein for evaluating protein turnover rates is the fact that the (15)N dose is spread among all proteinogenic amino acids. The absorption has been improved by hydrolysing [(15)N]yeast protein with thermitase into a mixture of amino acids, dipeptides and tripeptides so that faecal analysis becomes unnecessary when determining turnover rates. The review shows that, in contrast to the application of single (15)N-labelled amino acids with resulting overestimation of protein turnover rates, the (15)N-labelled yeast protein thermitase hydrolysate represents the amino acid metabolism more closely without causing amino acid imbalances. The (15)N-labelled yeast protein thermitase hydrolysate leads to the estimation of reliable protein turnover rates, particularly in premature infants.
Asunto(s)
Recien Nacido Prematuro/metabolismo , Nitrógeno/metabolismo , Proteínas/metabolismo , Aminoácidos/metabolismo , Heces/química , Proteínas Fúngicas/metabolismo , Humanos , Recién Nacido , Cinética , Nitrógeno/orina , Isótopos de Nitrógeno/orina , Biosíntesis de Proteínas/fisiologíaRESUMEN
The aim of the study was to investigate the whole-body protein turnover, either before or after continuous, moderate ethanol-induced oxidative stress by red wine consumption over a relatively short period in healthy volunteers. Ten healthy adults received an individual regular diet over 20 days. After 10 days, the subjects consumed 0.4 ml ethanol kg(-1) day(-1) as red wine together with dinner over a 10-day period. After 8 and 18 days, respectively, a (15)N-labelled yeast protein was administered in a dosage of 4.2 mg kg(-1) body weight. Urine and faeces were collected over 48 h, respectively. The (15)N-enrichment was measured by isotope ratio mass spectrometry, whereas the protein flux rates were calculated by a three-compartment model. The whole-body protein turnover without/with red wine consumption amounted to 3.73±0.6 and 3.49±0.6 g kg(-1) day(-1) (not significant), respectively. Moderate alcohol consumption does not induce significant short-term changes in the whole-body protein turnover of healthy adults.
Asunto(s)
Consumo de Bebidas Alcohólicas , Etanol/farmacología , Proteínas/metabolismo , Adulto , Femenino , Alemania , Humanos , Masculino , Espectrometría de Masas , Isótopos de Nitrógeno , Estrés Oxidativo/efectos de los fármacos , Proteínas/efectos de los fármacos , Saccharomyces cerevisiae , Vino , Adulto JovenRESUMEN
The aim of this study was to investigate the hepatic microsomal and cytosolic functions by using the 13CO2 breath test in healthy subjects either before or after consumption of red wine. Twelve adults received [13C2]aminopyrine and L-[1-13C]phenylalanine together with a standardised dinner. Expired air samples were taken over 6 h. After a wash-out period, the subjects consumed 0.4 ml ethanol per kg per day together with dinner over a 7.5-day period on average. Thereafter, 13C-tracer administration was repeated under identical conditions. The 13CO2 enrichments were measured by isotope ratio mass spectrometry. The mean cumulative percentage 13C-dose recovery after administration of [13C2]aminopyrine and L-[1-13C]phenylalanine either without or with red wine consumption amounted to 17.0+/-4.4 vs. 14.7+/-3.1% (p=0.170) and 14.0+/-2.8 vs. 11.5+/-3.9% (p=0.084), respectively. Moderate alcohol consumption does not induce significant short-term changes of the microsomal and the cytosolic function of the human liver in healthy subjects.
Asunto(s)
Aminopirina/análisis , Pruebas Respiratorias , Isótopos de Carbono , Etanol/farmacología , Hígado/efectos de los fármacos , Fenilalanina/análisis , Adulto , Aminopirina/metabolismo , Dióxido de Carbono/análisis , Estudios Cruzados , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Hígado/metabolismo , Masculino , Microsomas Hepáticos/efectos de los fármacos , Microsomas Hepáticos/metabolismo , Fenilalanina/metabolismo , Vino , Adulto JovenRESUMEN
The aim of this study was to investigate the hepatic microsomal and mitochondrial functions by using the 13CO2-breath test in healthy subjects either before or after the consumption of red wine. Fourteen adults received [13C]methacetin and [methyl-13C]methionine together with a standardised dinner. Expired air samples were taken over 6 h. After a wash-out period, the subjects consumed 0.4 ml ethanol/kg/day together with dinner over a 10-day period. Thereafter, 13C-tracer administration was repeated under identical conditions. The 13CO2-enrichments were measured by isotope ratio mass spectrometry. The mean cumulative percentage 13C-dose recovery (CPDR) after administration of [13C]methacetin and [methyl-13C]methionine either without or with red wine consumption amounted to 38.2+/-6.3 vs. 36.3+/-6.7% (p=0.363) and 9.5+/-3.3 vs. 8.8+/-2.5% (p=0.47), respectively. Moderate alcohol consumption does not induce significant short-term changes of the microsomal and the mitochondrial functions of the human liver in healthy subjects.
Asunto(s)
Consumo de Bebidas Alcohólicas/metabolismo , Pruebas Respiratorias/métodos , Isótopos de Carbono/análisis , Fase I de la Desintoxicación Metabólica/fisiología , Microsomas Hepáticos/metabolismo , Mitocondrias Hepáticas/metabolismo , Adulto , Estudios Cruzados , Etanol/metabolismo , Femenino , Humanos , Masculino , VinoRESUMEN
We used a combined tracer technique with the stable isotopes 13C and 15N to gain further insight into the metabolic changes that accompany supplementation of L-carnitine. The aim of the present study was to investigate whether L-carnitine supplementation can influence fat oxidation, protein turnover, body composition, and weight development in slightly overweight subjects. Twelve volunteers received an individual regular diet either without or with L-carnitine supplementation of 3 g/d for 10 days. Protein turnover and fat oxidation were investigated after administration of [15N]glycine and an [U-13C]algae lipid mixture. The 15N- and 13C-enrichment in urine and breath were measured by isotope ratio mass spectrometry. Body fat mass (BFM), total body water (TBW), and lean body mass (LBM) were calculated by using bioelectric impedance analysis. L-carnitine supplementation led to a significant increase in 13C-fat oxidation (15.8% v 19.3%; P = .021) whereas protein synthesis and breakdown rates (3.7 and 3.4 g/kg/d, respectively) remained unchanged, indicating that the increased dietary fat oxidation in slightly overweight subjects was not accompanied by protein catabolism.