Resistance of postprandial gastric functions and autonomic balance to taste stimulation.

Exposure to unpleasant tastes leads to disturbances of interdigestive gastric myoelectrical activity (GMA) and may affect sympathetic/parasympathetic balance (SPB). We made a careful study to determine whether taste stimulation modulates the postprandial GMA, SPB, and gastric emptying (GE) of a solid meal. Eighteen healthy volunteers (9F/9M) entered the study. On six separate days, we recorded a four-channel electrogastrogram from each volunteer during a 35-min fasting period, then for 90 min after ingestion of a solid test meal of 300 kcal. GE was measured using a 13C-octanoic acid breath test. Heart rate variability (HRV) analysis was simultaneously performed. At the start of the 21st min after the test meal, subjects received an agar cube delivering either a sweet, salty, sour, or bitter taste, which they kept in the mouth for 35 min. Control procedures involved sessions performed with a tasteless agar cube, and without any stimulation. There was no effect of the experimental intervention upon the relative power share of particular GMA rhythms. Stimulation with the salty and the bitter taste evoked a statistically significant increase in the dominant frequency, whereas the sweet and sour taste did not affect it. Taste stimulation did not interfere with the meal-induced rise in the dominant power, nor affect slow wave coupling. The kinetics of the solid GE remained unchanged by the intervention. None of the taste stimulations affected the postprandial SPB. Taste stimulation elicited after ingestion of a meal, in contrast to that during a fast, did not adversely modify the postprandial pattern of either the GMA or SPB, nor affect the GE of solids.

Roux-en-Y duodenojejunostomy improves gastric emptying in experimental obstruction of the distal duodenum.

INTRODUCTION: We undertook a comparative survey of gastric emptying (GE) kinetics after two variants of bypass surgery for upper bowel obstruction. MATERIAL & METHODS: In 10 dogs with experimental upper bowel obstruction, five were randomized to obtain gastrojejunal anastomosis (GA), and the other five received Roux-en-Y duodenojejunal anastomosis (DA). Duplicate scintigraphic measurements of GE of a solid meal were accomplished in every animal before surgery and during the early (2-3 weeks), medium (3 months), and late (6 months) post-operative period. The GE curves were fitted with a power-exponential function to derive the GE half time T½, and the curve shape parameter S. RESULTS: Early after surgery T½ slightly decreased by -18±21 min in the DA group and lengthened by 91±37 min in the GA group (p = 0.042). In both groups an increase in the S parameter was found then. In either group T½ gradually declined towards the basal value during the medium and late post-operative period. On the other hand, net differences relative to the basal situation in the S values appeared to be positive in the GA group (0.32±0.11 at 3 months; 0.64±0.19 at six months), and negative in the DA group (-0.30±0.09 at 3 months; -0.01±0.20 at six months). Hence a statistically significant contrast was found between those differences: p = 0.0022 at 3 months, and p = 0.045 at six months after the surgery. CONCLUSION: Roux-en-Y duodenojejunal anastomosis appears to be superior to the classical gastrojejunal anastomosis while restoring patency of the gastrointestinal passage in the case of upper bowel obstruction.

Effects of taste stimulation on gastric myoelectrical activity and autonomic balance.

Background/Aim: Sham feeding, reproducing the cephalic phase of digestion, and involving combined visual, olfactory, and taste stimulation affects gastrointestinal motility and secretory functions of the digestive system, as well as the sympathetic/parasympathetic balance (SPB). In this study, we aimed to check if taste stimulation with a single flavor affects the gastric myoelectrical activity (GMA) and/or SPB. Materials and Methods: Eighteen healthy volunteers underwent, on four separate days, 30-min electrogastrographic and electrocardiographic recordings: basal, with stimulation - while keeping in the mouth an agar cube with taste-delivering substance, and postexposure. Concentrations of saccharose, NaCl, citric acid, and quinine hydrochloride within the cubes were adjusted to 100-fold the individual taste recognition thresholds. SPB was determined from the heart rate variability (HRV) analysis of the recorded electrocardiograms. Results: A moderate but statistically significant increase in tachygastria and bradygastria percentage time share was observed, regardless of the type of taste applied. Bitter taste elicited a considerable decrease in the normogastria time share (from 82.8 ± 2.5% to 73.5 ± 3.5%, P = 0.00076) and a diminution of the dominant frequency (from 3.07 ± 0.08 to 2.90 ± 0.10 cycles per minute (cpm) postexposure, P = 0.01). Sour taste brought about a drop of the dominant power (from 42.5 ± 1.1 to 40.1 ± 1.4 dB, P = 0.0015). Two tastes hindered propagation of the gastric slow waves - the average percentage of slow wave coupling decreased from 77.9 ± 3.1% to 69.5 ± 3.1% (P = 0.0078) and from 74.6 ± 2.5% to 68.2 ± 2.8% (P = 0.0054) with the bitter and the salty taste, respectively. Stimulation with sweet, salty, or sour taste evoked a significant decrease in the high frequency component of the HRV, whereas bitter taste did not affect the SPB. Conclusions: Oral stimulation with tastes subjectively perceived as unpleasant brings about disturbances of the interdigestive GMA. This, however, does not coincide with its effect upon SPB.

Scrutiny of 13C-phenylalanine breath test reproducibility.

We evaluated the reproducibility of the 13C-phenylalanine breath test (13C-PheBT). On three separate days, 21 healthy volunteers (11 F and 10 M) underwent 13C-PheBT with 100 mg l-[1-13C]phenylalanine taken orally. Short-term reproducibility was evaluated with paired examinations taken 3 days apart; paired examinations separated by 23 days (median) served for the medium-term reproducibility assessment. Expiratory air was sampled at 19 points throughout 3 h. Determined limited reproducibility of the 13C-PheBT must be taken into consideration while interpreting the results of this diagnostic tool. The results of this study imply the following conclusions: (i) From among the three parameters examined, the cumulative 13C recovery area under the curve (AUC) offers much better reproducibility than the maximum momentary 13C recovery in the expiratory air (Dmax) or the time to reach the maximum momentary 13C recovery (Tmax) (ii) Collection of the breath air samples for 2 h results in a much better reproducibility of AUC, than for 1 h only; (iii) Reproducibility of 13C-PheBT is affected neither by the duration of the time gap between repeated tests nor by gender; (iv) Comparison with data obtained formerly reveals that reproducibility of the 13C-PheBT is worse than either that of of the 13C-methacetin (13C-MBT) or the 13C-alpha-ketoisocaproic acic (13C-KICA-BT) breath tests. This finding will have to be taken into consideration while interpreting the results of this diagnostic tool.

(13)CO2 breath tests in non-invasive hepatological diagnosis.

In liver diagnostics, a simple, non-invasive test with high sensitivity and specificity is permanently being sought in order to assess the degree of liver damage. In addition to liver biopsy, algorithms using blood parameters or elastometry are used in clinical practice. However, these methods do not provide information about the true liver reserve, so the liver breath test seem to be a promising diagnostic tool. The basis of this test depends on the ability of particular hepatocyte enzyme systems to metabolise a tested substance labelled with a stable carbon isotope. The kinetics of (13)CO2 elimination with expiratory air then permits quantitative assessment of the functional liver reserve and the degree of organ damage. In this paper the most commonly used tests, grouped according to the main metabolic pathways, are described. The usefulness of liver breath tests in specific clinical situations, both as a diagnostic and prognostic tool, is presented.

The effect of drugs and stimulants on gastric myoelectrical activity.

Electrogastrography (EGG) is a non-invasive diagnostic method useful for the registration and analysis of gastric myoelectrical activity. Abnormalities within an electrogastrogram were found to correlate with a number of disorders and symptoms, like functional dyspepsia, diabetic gastroparesis and terminal hepatic or renal failure. The EGG is also a valuable diagnostic method enabling the evaluation of the effect of drugs on gastric myoelectrical activity, which can be intentional, as in the case of prokinetics, or can have an adverse character. Our review focuses on drugs with a proven impact on gastric myoelectrical activity and hence on the electrogastrogram. The paper assembles and discusses the results of investigations dealing with changes in the electrogastrograms evoked by various drugs. Moreover, the mechanisms of the influence on the gastric myoelectrical activity of drugs, curative substances and stimulants are presented.

Combined oral contraceptives affect liver mitochondrial activity.

OBJECTIVES: To examine liver mitochondrial function in women using combined oral contraceptives (COCs) containing ethinylestradiol. METHODS: A breath test after oral administration of 1 mg/kg (13)C-alpha-ketoisocaproic acid ((13)C-KICA) and 20 mg/kg L-leucine was performed twice: (i) in 15 women on day 14, 15, 16, 17 or 18 of COC intake, and between day 1 and 5 of the withdrawal bleeding; and (ii) in 15 regularly menstruating females not taking hormonal contraceptives: during the luteal phase, between the 18th and the 22nd day of the cycle, and again between day 1 and 5 of the menstruation. RESULTS: In women on COCs the maximum (13)C elimination in breath air (Dmax) was higher (26.8 ± 1.6%/h) than during withdrawal bleeding (23.5 ± 1.2%/h; p = 0.012). The time to reach the Dmax was similar on the two study days: 33.3 ± 2.4 min during the phase of pill intake vs. 37.0 ± 2.5 min during the pill-free interval. The one-hour cumulative breath (13)C elimination was greater after two weeks of COC intake than during the withdrawal bleeding: 17.49 ± 1.03% vs. 15.32 ± 0.85% (p = 0.024). In the control group no menstrual cycle phase-dependent fluctuations in the results of the (13)C-KICA breath test were observed. CONCLUSION: The metabolism of (13)C-alpha-ketoisocaproic acid augments during the intake of COCs containing ethinylestradiol, reflecting enhanced liver mitochondrial metabolic activity.

Impact of combined oral contraceptives containing ethinylestradiol on the liver microsomal metabolism.

OBJECTIVES: To check whether currently used combined oral contraceptives (COCs) containing ethinylestradiol (EE) affect the liver microsomal metabolism. METHODS: (13)C-methacetin breath test ((13)C-MBT) - a sensitive non-invasive probe of cytochrome P-450 1A2 activity - was performed in 15 women on day 14, 15, 16, 17 or 18 of intake of their COC (containing EE), and between day 1 and 5 during the withdrawal bleeding, as well as in nine women not using hormonal contraception during the luteal phase of their cycle (between the 17th and the 23rd day), and between day 1 and 5 during menstruation. RESULTS: The maximum breath (13)C elimination was significantly lower during the phase of intake of contraceptive pills than during withdrawal bleeding: 31.5 ± 2.2 %/h vs. 38.2 ± 1.9 %/h (p = 0.0045), whereas the time to reach it was similar on the two study days: 21.2 ± 1.2 min vs. 21.0 ± 1.1 min. Between the 27th and the 180th min of observation the cumulative breath (13)C elimination was statistically significantly lower during intake of the pill than during withdrawal bleeding. No significant menstrual cycle phase-dependent fluctuations in the results of the (13)C- methacetin breath test were observed in the control group. CONCLUSION: COCs containing EE markedly inhibit hepatic microsomal function. This phenomenon must be taken into consideration when interpreting results of (13)C-MBT.

Reproducibility of two ¹³CO2 breath tests dedicated to assess pancreatic exocrine function.

The aim of this study was to check on the reproducibility of two breath tests intended to test the pancreatic exocrine function accomplished with (13)C-mixed triglyceride ((13)C-MTG) or cornflakes naturally enriched in (13)C ((13)C-CF). The (13)CO2 content within breath samples was determined with isotope-selective non-dispersive infrared spectrometry. A 72-h monitoring performed in healthy subjects revealed that a statistically significant rise in breath (13)CO2 occurs between the 1st and the 9th hour and between the 1st and the 24th hour after intake of a test meal containing 300 mg (13)C-MTG (n=10) or 100 g (13)C-CF (n=12), respectively. In another two groups of 12 healthy volunteers each, short-term reproducibility of the two tests was assessed with paired examinations taken at a median interval of two days, whereas paired examinations separated by a median of 20 days served for the medium-term reproducibility assessment. In the case of either test, the medium-term reproducibility was not any worse than the short-term one. The reproducibility of the (13)C-CF breath test tended to be slightly worse than that of the (13)C-MTG breath test: a least detectable difference in 6-h cumulative (13)C breath excretion (which is expressed as the percentage of the administered dose of the substrate) amounted to 2.7 and 4.4 % (short-term reproducibility) and to 3.5 and 4.4 % (medium-term reproducibility) in the case of the (13)C-MTG breath test and the (13)C-CF breath test, respectively. It is concluded that both tests offer a satisfactory reproducibility for use within a clinical setting. In case the lipolytic and the amylolytic activity would be required to be examined in the same patient, the (13)C-CF breath test can be executed on the next day following the (13)C-MTG breath test, whereas reciprocally, a 1-day break is recommended before accomplishment of a (13)C-MTG breath test following a (13)C-CF breath test.

Potent inhibitory effect of alcoholic beverages upon gastrointestinal passage of food and gallbladder emptying.

BACKGROUND AND AIMS: Current knowledge about the effect of alcoholic beverages on postprandial functioning of the digestive system is scarce and inconsistent. This study addresses their influence upon meal movement along the gut and meal-induced gallbladder emptying. METHODS: Three examination blocks involved each 12 healthy volunteers. Ingestion of a solid 1485 kJ meal was followed by intake of 400 ml beer (4.7%vol), 200 ml red wine (13.7%vol) or 100 ml whisky (43.5%vol) or matching volumes of control fluids. Gastric myoelectrical activity and emptying, orocecal transit and gallbladder emptying was monitored noninvasively. RESULTS: Alcoholic beverages (beer, red wine, whisky) caused a significant slowdown of the gastric evacuation of the solid meal, the delay being the more potent, the greater was the concentration of ethanol. This inhibitory effect was not caused by interference with the gastric myoelectric activity. Alcoholic beverages produced only by fermentation (beer, red wine), at odds with the effect of their counterpartying aqueous ethanol solutions, did not elongate the orocecal transit of the solid food. Products of distillation-whisky and high proof ethanol solution--elicited a profound delay of the orocecal transit. Alcoholic beverages exerted an inhibitory effect upon the meal-stimulated gallbladder emptying, the magnitude of which increased in the order: beer → red wine → whisky. CONCLUSION: Alcoholic beverages exert an inhibitory effect upon the gastric emptying of a solid food and the meal-induced gallbladder emptying, whereas the effect upon the orocecal transit depends on the type of a beverage-whisky elicits a delay but beer or red wine are devoid of this effect.

Comparison of two dosage regimens of the substrate for the [13C]methacetin breath test.

The [(13)C]methacetin breath test ([(13)C]MBT)--a valuable non-invasive tool dedicated to the assessment of the liver metabolic capacity--still needs standardisation. The aim of this study was to check whether currently used dosage regimens of [(13)C]methacetin provide concordant [(13)C]MBT results in subjects with an atypical body constitution. Healthy volunteers: low body mass<55 kg (eight women), and high body mass>95 kg (eight large body frame men) were recruited. They underwent [(13)C]MBT on separate days, taking in random order [(13)C]methacetin: a fixed 75 mg dose (FX75), or a 1 mg kg(-1) body mass-adjusted dose (BMAD). Samples of expiratory air for (13)CO(2) measurement were collected over 3 h. The maximum momentary (13)C elimination in breath air occurred earlier and was higher following BMAD than with FX75 in the low body mass females (T (max) 14.6 ± 1.0 min vs. 22.1 ± 2.4 min, p = 0.019; D (max) 41.9 ± 2.9 % dose h(-1) vs. 36.6 ± 3.6 % dose h(-1), p = 0.071). In the high body mass men, T (max) remained unchanged, whereas D (max) was slightly higher with BMAD compared to FX75 (21.5 ± 3.2 min vs. 23.0 ± 3.0 min; 38.5 ± 2.9 % dose h(-1) vs. 32.3 ± 2.5 % dose h(-1)). It is concluded that in subjects with a body constitution outside the general population average, the dosage of the substrate may affect some results of the [(13)C]MBT. The dosage-related differences appear, however, to be insignificant if the result of the [(13)C]MBT is reported as a cumulative (13)C recovery in breath air.

C-methacetin breath test reproducibility study reveals persistent CYP1A2 stimulation on repeat examinations.

AIM: To find the most reproducible quantitative parameter of a standard (13)C-methacetin breath test ((13)C-MBT). METHODS: Twenty healthy volunteers (10 female, 10 male) underwent the (13)C-MBT after intake of 75 mg (13)C-methacetin p.o. on three occasions. Short- and medium-term reproducibility was assessed with paired examinations taken at an interval of 2 and 18 d (medians), respectively. RESULTS: The reproducibility of the 1-h cumulative (13)C recovery (AUC(0-60)), characterized by a coefficient of variation of 10%, appeared to be considerably better than the reproducibility of the maximum momentary (13)C recovery or the time of reaching it. Remarkably, as opposed to the short gap between consecutive examinations, the capacity of the liver to handle (13)C-methacetin increased slightly but statistically significantly when a repeat dose was administered after two to three weeks. Regarding the AUC(0-60), the magnitude of this fixed bias amounted to 7.5%. Neither the time gap between the repeat examinations nor the gender of the subjects affected the (13)C-MBT reproducibility. CONCLUSION: (13)C-MBT is most reproducibly quantified by the cumulative (13)C recovery, but the exactitude thereof may be modestly affected by persistent stimulation of CYP1A2 on repeat examinations.

Interference of acute cigarette smoking with [¹³C]methacetin breath test.

It is essential to establish whether and how environmental factors affect the reliability of [(13)C]methacetin breath test ((13)C-MBT). In 12 healthy volunteers (smokers), a standard (13)C-MBT with 75 mg [(13)C]methacetin was performed twice in random order: on a control day without smoking and on another day with smoking two cigarettes antecedently. A considerable flattening of the curve of the momentary (13)C recovery within the expiratory air was observed when the (13)C-MBT was performed after smoking. The maximum of the momentary (13)C recovery, D(max), decreased from 37.20±2.58 to 25.39±2.29% dose/h (p=0.00052). Moreover, the time to reach D(max) was prolonged after cigarette smoking (26.5±3.1 vs. 16.5±1.9 min, p=0.0199). The curve of the cumulative (13)C recovery on the cigarette smoking day appeared to be shifted downwards, and statistically significant differences relative to the control situation were found between the 24th and 75th minute following [(13)C]methacetin administration. Smoking cigarettes immediately prior to the (13)C-MBT diminishes the ability of the liver to handle methacetin, and hence a possibility of such an interaction should be excluded in order to interpret the results of the test correctly.

Effect of the osmolality of caloric and acaloric liquids on gastric myoelectrical activity in humans.

BACKGROUND: The aim was to establish the effect of the osmolality of orally consumed liquids on gastric myoelectrical activity (GMA). MATERIAL/METHODS: Twenty-five healthy volunteers (13 women, 12 men aged 29.4+/-1.4 [SE] years) underwent five examinations on separate days. After a 20-min basal electrogastrographic recording, the volunteers drank 400 ml of a) bi-distilled water, b) 0.9% NaCl, osmolality 286 mmol/kg, c) 2.9% NaCl, osmolality 827 mmol/kg, d) 5% glucose, osmolality 282 mmol/kg, energy density 209 kcal/l, or e) 15% glucose, osmolality 836 mmol/kg, 627 kcal/l. Then the registration of GMA was continued for 60 min. Gastric emptying was measured with the 13C-acetate breath test. RESULTS: Compared with distilled water, the isotonic glucose drink elicited a positive chronotropic influence on and stabilization of GMA. At the transition from isotonicity to hypertonicity, a pronounced destabilization of GMA was observed, with opposite directions of changes brought about by the presence or absence of a caloric load; bradygastria was manifested after the energy-free hypertonic NaCl solution whereas hypertonic glucose evoked a tachygastric pattern. A marked delay in gastric emptying was found with both hypertonic drinks. CONCLUSIONS: Osmolality and its interplay with chemical composition/energy density must be taken into account when choosing a test meal for an electrogastrographic examination and interpreting its results. Of the five fluids examined, isotonic glucose appeared to be the drink least disturbing to GMA.

Normative values for the 13C-mixed triglyceride breath test in two age groups.

BACKGROUND: To investigate if age affects the results of the 13C-mixed triglyceride (13C-MTG) breath test. MATERIAL/METHODS: Two groups of 12 healthy subjects (group Y, 25.0+/-0.7 years; group MA, 48.8+/-2.4 years), each comprising 6 men and 6 women, were examined. The fasted volunteers had a 349-kcal test breakfast of 50 g of white bread with 30 g of butter to which 300 mg of 13C-MTG was added. Then a series of samples of exhaled air for the measurement of 13CO2 concentration was collected over a period of 9 hours. RESULTS: A maximum momentary 13CO2 breath excretion of 9.6+/-0.5%dose/h at 295+/-19 min in the young subjects and of 9.4+/-0.4%dose/h at 270+/-15 min in the middle-aged volunteers was observed. The group curves of cumulative 13C recovery in breath air exhibited a virtually overlapping time course. The 6-h cumulative 13C recovery amounted to 32.01+/-1.78%dose and 31.84+/-1.73%dose in the Y and MA groups, respectively. Extension of the collection of breath air samples from the standard six to nine hours resulted in an increase in the cumulative 13C recovery by 51.5+/-3.2%. Accordingly, the 9-h cumulative 13C recovery was 47.59+/-2.26%dose and 48.28+/-2.36%dose in the Y and MA groups, respectively. CONCLUSIONS: An age difference of over two decades does not compromise intrajejunal lipolytic activity taken as a measure of pancreatic exocrine function. Therefore reference values for the 13C-MTG breath test can be obtained from a population of healthy subjects of a relatively wide age range.

Gastric myoelectrical activity in patients with primary biliary cirrhosis.

OBJECTIVE: To examine gastric myoelectrical activity in patients with primary biliary cirrhosis (PBC). MATERIALS AND METHODS: The study comprised 11 female PBC patients (average age 53.4 years, range 43-70) and two aged-matched control groups: 11 (53.4 years, range 37-78) healthy women, and 10 female patients with chronic hepatitis C, CHC (53.9 years, range 35-66), who were examined prior to administration of an antiviral therapy. Every subject underwent an electrogastrographic recording comprising a 30-min interdigestive and a 120-min postprandial period. RESULTS: Abnormal electrogastrograms, containing prolonged epochs of tachygastria in the postprandial phase were found in 2 out of 11 (18.2%) patients having both stage IV of the Scheuer's PBC classification, as well as in 1 patient out of 10 (10%) with CHC at stage F2 according to the METAVIR fibrosis score. CONCLUSION: Electrogastrographic abnormalities do not seem to be pathognomonic for the PBC as a disease, but rather would be considered an unspecific sequel of a morbid liver affection.

Ability to digest starch assessed noninvasively with a 13CO2 breath test - comparison of results obtained in two groups of different age.

BACKGROUND: We evaluated the effect of age on the results of a cornflakes breath test that determines the efficiency of starch digestion. MATERIAL/METHODS: Two groups of 12 fasted healthy subjects (group Y, 24.7+/-0.6 years; and group MA, 49.7+/-1.3 years) consumed a 521-kcal test breakfast of 100 g cornflakes naturally abundant in 13C (-14.00 per thousand 13C enrichment relative to the Vienna Pee Dee belemnite standard). Then, the 13CO2 concentration was measured in samples of exhaled air collected over 9 hours. RESULTS: We noted a maximum momentary 13CO2 breath excretion of 7.54+/-0.19% dose/h at 298 +/- 15 minutes in group Y and 7.70+/-0.27% dose/h at 305+/-10 minutes in group MA. The group curves of the cumulative 13C recovery in breath air exhibited a virtually overlapping time course. The 6-hour cumulative 13C recovery was 29.33+/-0.70%dose in group Y and 29.87+/-1.18%dose in group MA. Extending the collection period from 6 to 9 hours produced an increase in the cumulative 13C recovery of 58.4+/-2.1%. The 9-hour cumulative 13C recovery was 46.58+/-1.04%dose in the Y group and 46.93+/-1.84%dose and the MA group. CONCLUSIONS: An age difference of more than 2 decades was not associated with a negative impact on the in vivo ability to digest starch. The reference values of the cornflakes breath test can be derived from healthy subjects in a relatively wide age range.

[Measurement of the orocaecal transit time after an oral lactulose load--does the fasting breath hydrogen concentration affect the feasibility of the test?]. / Pomiar czasu pasazu ustno-katniczego po doustnym obciazeniu laktuloza--czy wysokosc stezenia wodoru w wydychanym powietrzu na czczo determinuje wykonalnosc badania?

UNLABELLED: The study evaluated the influence of a fasted hydrogen breath concentration on the feasibility of an ambulatory measurement of the orocaecal transit time (OCTT). MATERIAL AND METHODS: Forty-two healthy subjects (36 women, 6 men, aged 27.0 +/- 8.5 year) consecutively reporting themselves for an OCTT measurement were included. Breath hydrogen concentrations were measured in the fasted state and at 10-min intervals for maximally up to 5 h after intake of a liquid 260-kcal test meal containing 10 g lactulose. RESULTS: Fasting breath H2 concentrations of < or = 20 ppm or > 20 ppm were found in 30 (71.4%) and 12 (28.6%) subjects, respectively. Determination of the OCTT at all 4 cut-off thresholds (5, 10, 15 and 20 ppm) was possible in 39 (92.9%) subjects. This group comprised all the subjects exhibiting a high (> 20 ppm) breath hydrogen concentration. In one subject the OCTT was determined for either the 5 or the 10 ppm threshold, in another subject for 5 ppm only, whereas in one volunteer no increase in the breath hydrogen occurred. CONCLUSION: Suggested by the literature data qualification criterion, defined as fasted breath hydrogen concentration < or = 20 ppm, does not determine the feasibility of the measurement of OCTT by means of a hydrogen breath test after an oral lactulose load.

A systematic study of a neutral meal suitable for subjects undergoing 13CO2 breath tests.

BACKGROUND: Some 13CO2 breath tests require prolonged breath sampling. The study aimed to validate a meal which could be served to subjects without interference with the measured breath 13CO2 profile. MATERIAL/METHODS: Eight healthy volunteers were examined on three separate days. On two occasions they took equicaloric meals of 320 kcal composed of foodstuffs known to be poor in 13CO: cooked rice (R) or a wheat bread sandwich with butter and ham (S). On the control day they fasted. Samples of expiratory air were taken every 15 min for 6 hours. The 13CO2 concentration in the samples was measured by isotope ratio mass spectrometry. Statistical analysis involved repeated measures analysis of variance (RANOVA). RESULTS: The intra-subject variability of breath 13CO2 concentration was remarkably low on the three study days, as reflected by mean coefficients of variation (CV) of 0.90+/-0.32%, 0.79+/-0.19%, and 0.80+/-0.34% for the control, meal S, and meal R days, respectively (RANOVA: F2;14=0.296, p=0.75). RANOVA indicated a strong effect of a meal on inter-subject variability of breath 13CO2 concentration (F2;46=390.62 p<0.000001). Post hoc comparisons revealed a mean CV of 1.64+/-0.37% on the control day, 3.62+/-0.18% after ingestion of S, and 3.81+/-0.24% after meal R (both p=0.000128 vs. the control). Nevertheless, with neither test meal did RANOVA disclose at any time a statistically significant deviation in breath 13CO2 concentration from the basal fasted value. CONCLUSIONS: Both the test meals fulfilled the requirement of neutrality as concerns a null effect on the breath 13CO2 profile.