[How do adolescent inpatients experience seclusion and other coercive measures?]. / Hoe beleven opgenomen adolescenten separatie en andere vormen van dwang?

BACKGROUND: The reduction of coercive measures in psychiatry, particularly of seclusion, is considered to be a matter of some urgency. When policy changes with regard to coercive measures are being considered, the wishes and preferences of patients should be taken into account. Up till now, however, there have not been any studies that have examined how adolescent inpatients feel about coercive measures. AIM: To examine the way adolescent inpatients feel about seclusion and other forms of coercive measures. METHOD: Adolescent inpatients in a Dutch centre for orthopsychiatry (n = 34) were asked about their experiences with and their thoughts on coercive measures in general and on seclusion in particular. RESULTS: Thirty-two respondents took part. More than half of the 18 adolescents who had had prior experiences of coercive measures preferred seclusion to involuntary medication. CONCLUSION: Policy-makers who want to reduce coercive measures in psychiatry should not focus primarily on the reduction of seclusion. Patient preferences, which vary depending on the nature of the patient population, need to be considered carefully and taken into account.

Improvement of spontaneous speech in early stage Alzheimer's with rivastigmine.

OBJECTIVES: Placebo-controlled trials have shown that rivastigmine can delay cognitive deterioration in patients with mild to moderate Alzheimer's disease (AD). Benefits on cognitive functioning, as measured with the ADAS-Cog, occur on a daily dose of 6-12 mg when used for at least 6 months. The effect of rivastigmine on the adequacy of spontaneous speech is unknown. This study aimed to (i) compare the spontaneous speech of AD patients with the spontaneous speech of persons with normal cognition, (ii) compare the spontaneous speech of the same group of AD patients before and after treatment with rivastigmine. METHODS: Spontaneous speech of AD patients (n=9) was compared with that of healthy elderly volunteers (n=8). In the patient group, spontaneous speech was analysed before and after treatment with rivastigmine. RESULTS: Before treatment, 100% discrimination was found between the spontaneous speech of AD patients and of healthy volunteers based on two linguistic parameters: empty words and compound sentences. After treatment with rivastigmine the spontaneous speech of the AD patients improved on these two variables, while the ADAS-Cog scores decreased. Mean interval between the two spontaneous speech samples was 8.89 months. CONCLUSION: Assessment of spontaneous speech might be a valid parameter to discriminate between normal cognition and AD, and to evaluate the effects of anti-AD medication.

Peritoneal protein losses and cytokine generation in automated peritoneal dialysis with combined amino acids and glucose solutions.

OBJECTIVES: Protein-energy malnutrition as a consequence of deficient protein intake frequently occurs in peritoneal dialysis (PD) patients. Previously, we showed that peritoneal dialysate containing a mixture of amino acids (AA) and glucose has anabolic effects. However AA-dialysate has been reported to increase intraperitoneal protein and AA losses and the release of proinflammatory cytokines (interleukine-6 (IL-6) and tumor necrosis factor alpha (TNFalpha)). We investigated the effect of AA plus glucose (AAG) solutions on peritoneal protein losses and cytokine generation. METHODS: In 6 patients on standard automated peritoneal dialysis (APD) 12 APD sessions of 6 cycles each were performed during the night using dialysate containing 1.1% AA plus glucose or glucose alone as control. Protein losses and TNFalpha and IL-6 concentrations were measured in dialysates separately collected from nightly cycling and daytime dwell. RESULTS: The 24 hour-protein losses with AAG (median 6.7 g, range 4.7-9.4 g) were similar to control dialysate (median 6.0 g, range 4.2-9.2 g). Daytime dialysate IL-6 levels were higher after nightly AAG dialysis than after control dialysis (142 pg/ml and 82 pg/ml, respectively, P<.05). TNFalpha concentrations were very low. CONCLUSION: Nightly APD with amino acids containing dialysate was associated with an increase in peritoneal IL-6 generation during the day. The addition of AA to standard glucose dialysis solutions did not induce a significant increase of peritoneal protein losses.

Minimum protein requirements in liver cirrhosis determined by nitrogen balance measurements at three levels of protein intake.

Nitrogen balance at three levels of protein intake was measured in eight patients with cirrhosis of the liver; moreover, at each level of protein intake, the effects on nitrogen balance of branched-chain amino-acid enriched protein and natural protein were compared. From these nitrogen balance data, minimum protein requirements were calculated by linear regression analysis. The patients were in a negative nitrogen balance on a 40 g protein diet (-0.75 +/- 0.15 gN.), and in positive nitrogen balance on 60 g (+1.23 +/- 0.22 gN.) or 80 g of protein per day (+2.77 +/- 0.20 g N.). Their mean minimum protein requirement (48 +/- 5 g of protein/day or 0.75 g/kg/day) is higher than expected in healthy people; the safe level of protein intake (mean + 2 sd) is 58 g per day or 1.2 g/kg/day. Nitrogen balances and protein requirements were not different on branched-chain amino-acid enriched diets. The physical condition of the patients improved when they came into positive nitrogen balance; the higher rates of protein intake were well tolerated without onset of encephalopathy. We conclude that protein requirements are elevated in cirrhosis of the liver; diets supplying less than 60 g of protein per day should not be prescribed in long term treatment of cirrhotic patients.

Influence of the 13C-enrichment of the habitual diet on a 13CO2 breath test used as an index of liver glycogen oxidation: a validation study in western Europe and Africa.

A diet containing naturally 13C-enriched carbohydrate combined with a 13CO2 breath-test analysis can be used to monitor liver glycogen oxidation in persons used to a diet low in 13C, e.g., the Western European diet. In this study, we evaluated this test principle further by changing the way we label the glycogen pool. The 13C enrichment of exhaled CO2 was studied in two groups, one in Europe and one in Africa. The European group (n = 12) was accustomed to a diet low in 13C, and they went on a 13C-enriched study diet to identify liver glycogen. The African group (n = 6) was accustomed to a diet naturally high in 13C, and they went on a diet low in 13C. The basal 13C abundance in exhaled CO2 was higher in the African group (1.0879 At%; atmospheric 1.1 atom percent) than in the European group (1.0821 At%). During the study period, the parameters for liver glycogen oxidation--the 13CO2 enrichment plateau, the plateau duration, and the return to baseline time--did not differ between groups. The abundance of 13CO2 in exhaled CO2 over time in the two groups was similar but inverse. This study confirms the use of a 13CO2 breath test to monitor liver glycogen oxidation and demonstrates how to use such a test in persons accustomed to a diet high in 13C.

The 13CO2 breath test for liver glycogen oxidation after 3-day labeling of the liver with a naturally 13C-enriched diet.

OBJECTIVE: When naturally (13)C-enriched carbohydrate is used to label hepatic glycogen, (13)C-liver glycogen oxidation can be monitored subsequently by measuring the (13)C enrichment of breath CO(2) during a sedentary fast. In our previous breath test studies, we used a 1-d labeling protocol to enrich liver glycogen. Others found that after 3 d of labeling the liver glycogen (13)C enrichment is identical to the dietary carbohydrate (13)C enrichment. METHODS: We compared a diet protocol in which naturally (13)C-enriched carbohydrate was given for 3 d before the breath test with our previously applied 1-d labeling design. The (13)CO(2) breath test was combined with indirect calorimetry. The results were compared with those from our previous studies. In addition, we compared liver glycogen oxidation rates with those from our present technique and different techniques as used in other published studies. RESULTS: Six healthy volunteers were included in this study. The (13)C enrichment of breath CO(2) at plateau excretion level did not differ after 1 or 3 d on a labeling diet. However, the end of plateau time tended to be later after the 3-d diet, 14.3 h versus 12.5 to 13.5 h postprandially in the 1-d labeling studies. Also, the return to baseline time was later in the 3-d study, at 25.8 h versus 19.0 to 23.2 h postprandially after 1 d of labeling. The liver glycogen oxidation rate was similar in both techniques until 17 h postprandially. After this time the 3-d labeling protocol showed a higher level of liver glycogen oxidation. CONCLUSION: The results indicated that the labeling of liver glycogen is slightly less complete after 1 d on a (13)C-enriched diet as compared with 3-d labeling. Our (13)C breath test results compared rather well with studies from the literature using the (13)C-NMR technique, the D(2)O technique, or the (13)CO(2) breath method to measure liver glycogen oxidation.

Development of hexachlorobenzene porphyria in rats: time sequence and relationship with lipid peroxidation.

The relationship between the development of porphyria and free-radical formation induced by hexachlorobenzene was studied in iron-overloaded rats. The first sign of porphyria, an increase in porphyrins in the liver, was detected at day 22. Liver malondialdehyde was also increased at day 22. During the following weeks, liver porphyrins and malondialdehyde increased simultaneously, accompanied by a decrease in uroporphyrinogen decarboxylase activity and glucose-6-phosphate activity in liver, and a high excretion of porphyrins in the urine. In the rats given hexachlorobenzene, changes were detected in the pattern of lipids in the liver microsomes. In comparison with the controls, there were decreases in C20:4 and C22:5 fatty acids, whereas the fatty acid C20:3w6 was increased. In this study of hexachlorobenzene-induced liver damage there was no difference in the time course of the development of porphyria and that of lipid peroxidation.

Effect of dietary fish oil on blood levels of free fatty acids, ketone bodies and triacylglycerol in humans.

Although the reduction of serum triacylglycerol concentrations by dietary fish oil is a well-known effect, the exact mechanism of this effect has not been previously studied in human subjects. Therefore, the aim of this study was (i) to examine the effect of short-term fish oil supplementation on blood concentrations of ketone bodies, free fatty acids and triacylglycerol in healthy humans and (ii) to verify whether the observed relationships between these variables would be consistent with reduced lipolysis and/or enhanced hepatic fatty acid oxidation after fish oil supplementation. Twenty subjects (21-23 years, normal liver function tests) were randomly divided into two groups to supplement their usual diet with either 30 g/d of fish oil (n = 11) or olive oil (n = 9). Venous blood samples were drawn after an overnight fast, before and after 1, 3 and 7 d of fish oil/olive oil supplementation. Blood concentrations of triacylglycerol and free fatty acids decreased consistently after fish oil supplementation; the reduction was already significant after one day of fish oil (P < 0.001 for triacylglycerol and P = 0.01 for free fatty acids). In contrast, neither of these blood values changed after olive oil supplementation (P > 0.10). No significant changes in glucose, insulin or ketone body levels were observed in either group after supplementation. After fish oil, but not after olive oil supplementation, the ratio of blood ketone body levels to free fatty acid levels increased significantly (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

A crossed projection from the optic tectum to craniocervical premotor areas in the brainstem reticular formation. An anterograde and retrograde tracing study in the mallard (Anas platyrhynchos L.).

The optic tectum in birds receives visual information from the contralateral retina. This information is passed through to other brain areas via the deep layers of the optic tectum. In the present study the crossed tectobulbar pathway is described in detail. This pathway forms the connection between the optic tectum and the premotor area of craniocervical muscles in the contralateral paramedian reticular formation. It originates predominantly from neurons in the ventromedial part of stratum griseum centrale and to a lesser extent from stratum album centrale. The fibers leave the tectum as a horizontal fiber bundle, and cross the midline through the caudal radix oculomotorius and rostral nucleus oculomotorius. On the contralateral side fibers turn to ventral and descend caudally in the contralateral paramedian reticular formation to the level of the obex. Labeled terminals are found in the ipsilateral medial mesencephalic reticular formation lateral to the radix and motor nucleus of the oculomotor nerve, and in the contralateral paramedian reticular formation, along the descending tract. Neurons in the medial mesencephalic reticular formation in turn project to the paramedian reticular formation. Through the crossed tectobulbar pathway visual information can influence the activity of craniocervical muscles via reticular premotor neurons.

An intelligibility assessment of toddlers with cleft lip and palate who received and did not receive presurgical infant orthopedic treatment.

A randomized, prospective, clinical study was performed investigating the effects of presurgical infant orthopedic treatment (PIO) in children with unilateral cleft lip and palate (UCLP). The influence of PIO on speech intelligibility was evaluated with two groups, each consisting of 10 children with UCLP. One group used PIO during the first year of life, whereas the other group did not use the device. Eight children without cleft served as a second control group. Intelligibility was assessed by lay listeners using two methods: transcription and listener rating. The ratings proved to be reliable and to have sufficient validity, but they did not completely reflect intelligibility defined as the proportion of words understood by the listener. Children in the treatment group were rated as exhibiting greater intelligibility than those in the nontreatment group. However, data obtained by means of transcriptions indicated that, in fact, there were no group differences in actual intelligibility. Only in comparison with their noncleft peers were the children with cleft lip and palate significantly less well understood.

The behavior of H* and L* under variations in pitch range in Dutch rising contours.

A Dutch rising intonation contour can be realized either as a rise that begins low and ends mid-to-high ("low rise") or as a rise that begins mid and ends high ("high rise"). These two contours could either be the extremes on a phonetic continuum representing a single phonological contour, for instance L* H-H%, or be realizations of two phonologically different contours, L* H-H% and H* H-H%. In order to decide between these two analyses, listeners were asked to rate stimuli with different pitch ranges on a number of semantic scales whose meanings vary with pitch range. Our hypothesis was that H-tones are higher as the pitch range increases, while L* is lower. Two preliminary experiments, in which we presented F0 contours of high rises and low rises in a number of different pitch ranges, revealed that perceived surprise, rather than perceived prominence, is an appropriate response variable for measuring pitch range perception, where increased pitch range corresponds to higher H-tones and lower L*. Subsequently, listeners were asked to indicate the degree to which each of a number of appropriately manipulated stimuli expressed "Surprise." The results lend strong support to the hypothesis that the low rise and the high rise are categorically distinct contours of Dutch, and that their first tones are L* and H*, respectively.

Albumin and whole-body protein synthesis respond differently to intraperitoneal and oral amino acids.

Patients with peritoneal dialysis are at risk for malnutrition and hypoalbuminemia, which are indicators of poor outcome. Recently, it was shown that dialysis solutions containing amino acids (AAs) and glucose improve protein anabolism in peritoneal dialysis patients. We determined if the same solutions could increase the fractional synthesis rate of albumin along with whole-body protein synthesis. Changes in the fractional albumin synthetic rate reflect acute change in hepatic albumin synthesis. A random-order cross-over study compared the effects of Nutrineal (AA source) plus Physioneal (glucose) dialysate with Physioneal alone dialysate. Eight patients in the overnight fasting state were compared to 12 patients in the daytime-fed state. Fractional albumin synthetic rate and whole-body protein synthesis were determined simultaneously using a primed-continuous infusion of L-[1-(13)C]-leucine. Fractional albumin synthesis on AAs plus glucose dialysis did not differ significantly from that on glucose alone in the fasting or the fed state. Protein intake by itself (fed versus fasting) failed to induce a significant increase in the fractional synthetic rate of albumin. Conversely, the oral protein brought about a significant stimulation of whole-body protein synthesis. Our findings show that the supply of AAs has different effects on whole-body protein synthesis and the fractional synthetic rate of albumin.

Nocturnal oral glucose supplementation. The effects on protein metabolism in cirrhotic patients and in healthy controls.

Nocturnal glucose administration might prevent gluconeogenesis and concomitant protein loss due to hepatic glycogen depletion. In this study the effects of nocturnal oral glucose supplements on nitrogen metabolism were investigated in 8 cirrhotic patients and in 8 healthy controls. During the night, either polymeric glucose was given or water as placebo. In the patients with cirrhosis on placebo, nitrogen balance was not different from controls: -63 +/- 8 vs. -55 +/- 4 mg N/kg b.wt./9 h (mean +/- SEM). Cirrhotic patients had increased nocturnal protein turnover rates (measured with 15N-glycine) and increased early morning levels of free fatty acids (FFA), lactate, insulin, glucagon and growth hormone. After glucose, nitrogen balance improved by 36% in the cirrhotic group, with a decrease in protein turnover rates and a decrease in plasma levels of beta-hydroxybutyrate, urea and glucagon. In the controls, glucose had no effects on nitrogen balance, on protein turnover or on the hormone levels, except for reduced FFA and ketone body levels. These data show that nocturnal calorie supplements improve nitrogen balance during the night in cirrhotic patients but not in healthy controls. Long interprandial intervals should be avoided in cirrhotic patients.

The validity of bioelectrical impedance analysis in estimating total body water in patients with cirrhosis.

This study assessed the validity of bioelectrical impedance analysis (BIA) to predict total body water (TBW) in patients with cirrhosis. TBW was estimated by deuterium oxide dilution (D2O) and compared with TBW predicted by BIA in 27 patients with cirrhosis with and without ascites or edema (Group A), in a subgroup of 18 'dry' cirrhotics without clinical signs of fluid overload (Group B) and in 27 healthy controls. Three different BIA regression equations were used. In all three groups of subjects high correlation coefficients were obtained between D2O-TBW and BIA-TBW (r > 0.88). In the cirrhotic Group A, BIA significantly underpredicted D2O-TBW by all 3 equations (2.9-3.8 l) and the regression lines were different from the lines of identity by two equations. Standard errors of estimate were high in Group A (3.04-3.97 l) in comparison with Group B (1.79-2.46 l) and the controls (1.03-1.41 l). In the 'dry' cirrhotics (Group B) and in the controls, TBW was correctly predicted by two of three BIA equations, and regression lines were not significantly different from lines of identity. Correlation coefficients in Group B were higher than in Group A (r = 0.96-0.97 vs. 0.89-0.92) and were comparable with controls (r = 0.98-0.99). We conclude that BIA is not a valid method of estimating TBW in cirrhotic patients with ascites and edema. In cirrhotic patients without clinical signs of fluid overload BIA can be used to predict TBW, although accuracy is slightly lower than in healthy controls.

The effect of very low energy diets on the fatty acid composition of serum lipids.

The fatty acid composition of serum phospholipids, cholesteryl esters and triglycerides was measured in 11 obese individuals before and after 2 and 4 weeks treatment with a liquid diet providing about 600 kcal and 70 g protein per day. The patients received 20g of lipid, which was either maize oil and safflower oil (6 patients) or maize oil and evening primrose oil (5 patients). During treatment serum phospholipid linoleic acid (C18:2n-6) concentration remained constant, the dihomo-gamma-linolenic acid (C20:3n-6) concentration decreased by 44 percent in the safflower oil group and by 37 percent in the evening primrose oil group and the arachidonic acid (C20:4n-6) increased by 26 percent in the safflower oil group and by 20 percent in the evening primrose oil group. The increase in phospholipid arachidonate showed a significant positive correlation with total weight loss during the treatment period. These results suggest that during weight reduction there is a increased mobilization of arachidonic acid from tissues and a decreased rate of linoleic acid desaturation and elongation, which was not significantly influenced by providing gamma-linolenic acid in the diet.

Muscle glycogen does not interfere with a 13CO2 breath test to monitor liver glycogen oxidation.

Naturally 13C-enriched carbohydrate has been used to label the liver glycogen pool for metabolic studies. The utilization of this glycogen was then monitored by the appearance of 13CO2 in breath. Using this method, it is assumed that during sedentary fasting the contribution of muscle glycogen towards oxidation is negligible. We investigated the influence of a different level of 13C enrichment of muscle glycogen on the 13C enrichment of breath CO2 while the breath test was carried out. In six healthy volunteers, the muscle glycogen stores were grossly depleted by a cycling exercise prior to consumption of the 13C-enriched diet which was given over a 10 h period. The oxidation of liver glycogen was measured during an 18 h sedentary fast. The results were compared with a control group who had not depleted their muscle glycogen before labelling. A higher 13C enrichment of muscle glycogen did not interfere with two parameters of liver glycogen oxidation, i.e. the duration of the plateau phase of 13CO2 and the return to baseline time. It was also shown that the 13C-labelled muscle glycogen was still available after the 18 h fast because a strenuous exercise led to a rapid 13CO2 enrichment. It is concluded that muscle glycogen 13C enrichment does not invalidate a 13CO2 breath test to measure liver glycogen oxidation during a sedentary fast.

Incorporation and washout of orally administered n-3 fatty acid ethyl esters in different plasma lipid fractions.

The aim of the present study was to quantify the incorporation of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) into plasma lipids after oral administration of n-3 fatty acid ethyl esters, since little is known about the rate and pattern of incorporation into plasma lipid fractions. In addition, we aimed to obtain preliminary information regarding EPA half-life, which is needed to establish an optimal dosing schedule. Five healthy volunteers ingested two 8.5 g doses of n-3 fatty acid ethyl esters daily for 7 d, supplying 6.0 g EPA/d and 5.3 g DHA/d. The fatty acid compositions of plasma phospholipids (PL), cholesteryl esters (CE) and triacylglycerols (TAG) were determined during supplementation and during a washout period of 7 d. Half-lives of EPA and DHA were calculated. The proportion of EPA in PL showed a 15-fold increase after 7 d (P < 0.001), while DHA showed a smaller increase (P < 0.01). In CE, EPA also increased (P < 0.05), while DHA did not increase at all. Remarkably, incorporation of DHA into TAG was even higher than that of EPA. Half-life of EPA in PL ranged from 1.63 to 2.31 d (mean 1.97 (SE 0.15) d), whereas mean half-life of EPA in CE was 3.27 (SE 0.56) d. In three subjects, washout of EPA and DHA from TAG seemed to follow a bi-exponential pattern, with a short half-life (< 1 d) in the initial phase and a half-life of several days in the second phase. In conclusion, EPA ethyl esters are rapidly incorporated into plasma lipids, especially into PL. The relatively long half-life of EPA in plasma would permit a dosing schedule with intervals of > or = 12 h in supplementation studies.

Elevated protein requirements in cirrhosis of the liver investigated by whole body protein turnover studies.

1. In patients with cirrhosis of the liver and in healthy control subjects, the rates of nitrogen flux, protein synthesis and protein breakdown were studied, using a single oral dose of 200 mg of [15N]glycine as a tracer. The nitrogen flux through the amino acid pool was measured separately with both urinary ammonia and urinary urea as end products; the average value was used for further calculations. 2. Subjects were studied in the fed state, both on an adequate and a protein-restricted diet, and also in the fasting state. 3. The rates of protein synthesis were markedly increased in the patients, not only in the fed but also in the fasting state. Protein breakdown rates were increased in the patients in the fed state. 4. The nitrogen balance in steady-state conditions in the fed state was more positive in the patients, while their nitrogen loss in the fasting state was no higher than that of control subjects. 5. A hypothesis is put forward that the high protein requirements of cirrhotic patients could be caused by small and inadequate liver glycogen stores; due to these small stores, gluconeogenesis from amino acids will take place and lead to an extra amino acid loss even during short-term fasting. This increased amino acid loss could explain the elevated protein requirements in cirrhotic patients.

Pharmacokinetics of intravenous ATP in cancer patients.

OBJECTIVE: To characterise the pharmacokinetics of adenosine 5'-triphosphate (ATP) in patients with lung cancer after i.v. administration of different ATP dosages. METHODS: Twenty-eight patients received a total of 176 i.v. ATP courses of 30 h. Fifty-two infusions were given as low-dose infusions of 25-40 microg kg(-1) min(-1), 47 as middle-dose infusions of 45-60 microg kg(-1) min(-1) and 77 as high-dose infusions of 65-75 microg kg(-1) min(-1) ATP. Kinetic data of ATP concentrations in erythrocytes were available from 124 ATP courses. Results are expressed as mean +/- SEM. RESULTS: Most ATP courses in cancer patients were without side effects (64%), and side effects occurring in the remaining courses were mild and transient, resolving within minutes after decreasing the infusion rate. Baseline ATP concentration in erythrocytes was 1,554 +/- 51 micromol l(-1). ATP plateau levels at 24 h were significantly increased by 53 +/- 3, 56 +/- 3 and 69 +/- 2% after low-dose, middle-dose and high-dose ATP infusions, respectively. At the same time, significant increases in plasma uric acid concentrations were observed: 0.06 +/- 0.01, 0.11 +/- 0.01 and 0.16 +/- 0.01 mmol l(-1), respectively. The mean half-time for disappearance of ATP from erythrocytes, measured in five patients, was 5.9 +/- 0.5 h. CONCLUSIONS: During constant i.v. infusion of ATP in lung cancer patients, ATP is taken up by erythrocytes and reaches dose-dependent plateau levels 50-70% above basal concentrations at approximately 24 h.

Evaluation studies of the 13C-mixed triglyceride breath test in healthy controls and adult cystic fibrosis patients with exocrine pancreatic insufficiency.

The 13C-mixed triglyceride (13C-MTG) breath test (BT) is a safe and noninvasive method to measure exocrine pancreatic function. We examined the reproducibility of the 13C-MTG BT in a group of 17 healthy controls and 8 adult patients with cystic fibrosis (CF). In controls no statistically significant difference in percentage dose recovered (PDR) was found between the first and the second result of repeated tests: the mean values were 35.5 +/- 5.5 vs. 32.3 +/- 7.4 PDR (n = 17). Also in the group of CF patients (n = 8) no significant difference between duplicate tests was found: mean values 17.5 +/- 7.5 and 17.5 +/- 7.8 PDR, respectively. The coefficient of repeatability is 8 PDR for the controls and CF patients together. Two factors might influence the outcome of the test. First, individually measured CO2 excretion instead of the usually assumed 9 mmol/h/kg CO2 production might alter the result of the 13CO2-MTG BT. Therefore CO2 production was measured by indirect calorimetry in 12 healthy controls and 13 CF patients. Measured CO2 excretion was not significantly different between healthy controls and CF patients. Secondly, exercise might influence BT results due to its separate effects on both CO2 production and excretion. The influence of physical exercise at a level of 25 or 50 W was studied on a bicycle ergometer in 4 healthy controls during the last 5 min of each 30-min sampling period. Exercise gave lower test results, on average 85% of the PDR value at rest. Incidently, it was observed in 1 patient that use of 13C-enriched food during the day preceding the test caused inappropriately low test results in the 13C-MTG BT. The 13C-MTG BT is a test with a fair but less than desirable reproducibility. Test conditions should be standardized to eliminate confounding influences. Exercise should be limited or strictly defined. Diet on the day preceding the test should not contain naturally 13C-enriched food. There is no need to measure individual CO2 production.