The pathophysiology of bile acid diarrhoea: differences in the colonic microbiome, metabolome and bile acids.

Bile acid diarrhoea (BAD) is a common disorder resulting from increased loss of bile acids (BAs), overlapping irritable bowel syndrome with diarrhoea (IBS-D). The gut microbiota metabolises primary BAs to secondary BAs, with differing impacts on metabolism and homeostasis. The aim of this study was to profile the microbiome, metabolic products and bile acids in BAD. Patients with BAD diagnosed by SeHCAT testing, were compared with other IBS-D patients, and healthy controls. Faecal 16S ribosomal RNA gene analysis was undertaken. Faecal short chain fatty acid (SCFA) and urinary volatile organic compounds (VOCs) were measured. BAs were quantified in serum and faeces. Faecal bacterial diversity was significantly reduced in patients with BAD. Several taxa were enriched compared to IBS-D. SCFA amounts differed in BAD, controls and IBS-D, with significantly more propionate in BAD. Separation of VOC profiles was evident, but the greatest discrimination was between IBS-D and controls. Unconjugated and primary BA in serum and faeces were significantly higher in BAD. The faecal percentage primary BA was inversely related to SeHCAT. BAD produces dysbiosis, with metabolite differences, including VOC, SCFA and primary BAs when compared to IBS-D. These findings provide new mechanistic insights into the pathophysiology of BAD.

Lessons from rodent gastric bypass model of enteric hyperoxaluria.

PURPOSE OF REVIEW: The aim of the article is to review studies on bone health and oxalate metabolism/therapeutics in the obese rodent model of Roux-en-Y gastric bypass (RYGB) and examine pathways to decrease procedural morbidity. RECENT FINDINGS: Compared with controls, RYGB rodents have up to 40-fold more fat in their stool (steatorrhea) which positively correlates to increased urinary oxalate. These unabsorbed intestinal fatty acids bind calcium and prevent gut calcium oxalate formation, increasing soluble luminal oxalate availability and absorption (enteric hyperoxaluria). When intraluminal fecal fat exceeded about 175 mg/24 h in our model, more paracellular and transcellular oxalate transport across the distal colon occurred. Increasing dietary calcium and colonization with Oxalobacter formigenes reduced hyperoxaluria, whereas vitamin B6 supplementation did not. RYGB animals, when severely calcium deficient, had bone mineral density loss that could not be rescued with vitamin D supplementation. SUMMARY: The findings of hyperoxaluria, steatorrhea, and decreased bone mineral density are seen in both human and rodent RYGB. Our model suggests that a low-fat, low-oxalate diet combined with calcium supplementation can decrease urinary oxalate and improve skeletal bone health. Our model is a useful tool to study renal and bone RYGB effects. Studies of longer duration are required to further evaluate mechanisms of disease and durability of therapeutics.

Bile and fat excretion are biomarkers of clinically significant diarrhoea and constipation in irritable bowel syndrome.

BACKGROUND: Biomarkers in irritable bowel syndrome (IBS) may guide targeted therapy in this multifactorial disease. It has been suggested that 75% accuracy and cost <$500 categorise biomarkers as cost-effective. AIM: To identify differences in faecal bile acids, faecal fat and fasting serum C4 (7a-hydroxy-4-cholesten-3-one) and fibroblast growth factor 19 (FGF19) among patients with IBS-D, IBS-C and healthy controls and to determine accurate, cost-effective biomarkers for clinically relevant diarrhoea and constipation. METHODS: We assessed daily stool frequency and consistency (Bristol Stool Form Scale) from validated bowel diaries, 48 hours total and individual faecal bile acids, 48 hours faecal fat and weight, fasting serum C4 and FGF19, and colonic transit by scintigraphy from healthy volunteers (HV) and patients with IBS-D and IBS-C (Rome III criteria). We utilised multivariate logistic regression to determine biomarkers of clinically significant diarrhoea or constipation based on stool frequency, consistency and weight. RESULTS: Among the 126 HV (44M/82F, 37.5 ± 10.9 years [SD]), 64 IBS-D (5M/59F, 41.9 ± 12.2 years), and 30 IBS-C (0M/30F, 44.6 ± 10 years) patients, there were significant differences between all groups in stool weight, frequency, and consistency; in addition, there were differences in colonic transit at 48 hours, faecal fat, and total and individual faecal bile acids between IBS-D and IBS-C. Reduced total and primary faecal bile acids and increased faecal lithocholic acid were significant predictors of decreased faecal weight, frequency and consistency with AUC > 0.82 (sensitivity >76%, specificity >72%). Total and primary faecal bile acids and faecal fat were significant predictors of increased stool weight, frequency and consistency with AUC > 0.71 (sensitivity >55%, specificity >74%).The faecal parameters had a 11.5 positive likelihood ratio in predicting elevated faecal weight. CONCLUSIONS: Faecal bile acids and faecal fat are cost-effective and accurate biomarkers associated with significant bowel dysfunction among IBS-D and IBS-C patients.

Increased hydrophilic plasma bile acids are correlated with protection from adiposity in skin-specific stearoyl-CoA desaturase-1 deficient mice.

Stearoyl-CoA desaturase 1 (SCD1) catalyzes the rate limiting step in monounsaturated fatty acid synthesis by inserting a double bond at the delta-9 position of long-chain fatty acids. SCD1 converts stearate (18:0) to oleate (18:1n9) and palmitate (16:0) to palmitoleate (16:1n7), respectively. Mice with global and skin-specific deletion (SKO) of SCD1 exhibit increased whole body energy expenditure and protection against diet-induced adiposity, hepatic steatosis, insulin sensitivity and glucose intolerance. The mechanisms that link cutaneous lipid homeostasis with whole body energy balance are presently unknown. In this study, we reveal that SKO mice demonstrate increased skin surface free cholesterol, decreased circulating total cholesterol and increased taurine-conjugated and hydrophilic bile acids. Tauro-ß-muricholic acid, which is a marker of extrahepatic bile acid synthesis, is significantly elevated in SKO plasma. Bile acid signaling through the bile acid-specific receptor TGR5 is known to be protective against obesity and metabolic disease; a phenotype that is similar to SKO mice. We therefore examined TGR5 expression and its downstream mediator, DIO2, in various tissues and found that both TGR5 and DIO2 expression were significantly increased in brown adipose tissue. In sum, we suggest that skin-derived bile acids are involved in the lean and metabolically healthy phenotype of SKO mice.

Description of analytical method and clinical utility of measuring serum 7-alpha-hydroxy-4-cholesten-3-one (7aC4) by mass spectrometry.

BACKGROUND: Imbalance of bile acids (BA) homeostasis in the gastrointestinal tract can lead to chronic diarrhea or constipation when BA in the colon are in excess or low, respectively. Since both disturbances of bowel function can result from other etiologies, identifying BA imbalance is important to tailor treatment strategies. Serum concentrations of 7-alpha-hydroxy-4-cholesten-3-one (7aC4), a precursor in bile acid synthesis, reflect BA homeostasis. Here we describe a method to accurately measure serum 7aC4 and evaluate the clinical utility in patients with diarrhea or constipation phenotypes. METHODS: Serum 7aC4 is measured after acetonitrile protein precipitation using C18 liquid chromatography, tandem mass spectrometry, and deuterium-labeled 7aC4 internal standard. Assay performance including linearity, precision, and accuracy was assessed using waste serum samples. The reference interval was established in healthy individuals without BA-altering conditions or medications. Clinical performance was assessed in patients with irritable bowel syndrome. RESULTS: The method precisely and accurately measured 7aC4 in human serum from 1.4-338ng/mL with no ion suppression or interference from related 7-keto-cholesterol. Central 95th percentile reference interval was 2.5-63.2ng/mL. Lower serum 7aC4 was found in patients with constipation with sensitivity/specificity of 79%/55% compared to healthy controls. Higher 7aC4 was found in patients with bile acid diarrhea (BAD) compared to those without BAD with sensitivity/specificity of 82%/53%. CONCLUSIONS: We have developed a sensitive and precise assay for measuring the concentration of 7aC4 in serum. The assay can be used to screen for diarrhea caused by bile acid malabsorption.

Steatorrhea and Hyperoxaluria in Severely Obese Patients Before and After Roux-en-Y Gastric Bypass.

BACKGROUND AND AIMS: Hyperoxaluria after Roux-en-Y gastric bypass (RYGB) is generally attributed to fat malabsorption. If hyperoxaluria is indeed caused by fat malabsorption, magnitudes of hyperoxaluria and steatorrhea should correlate. Severely obese patients, prior to bypass, ingest excess dietary fat that can produce hyperphagic steatorrhea. The primary objective of the study was to determine whether urine oxalate excretion correlates with elements of fat balance in severely obese patients before and after RYGB. METHODS: Fat balance and urine oxalate excretion were measured simultaneously in 26 severely obese patients before and 1 year after RYGB, while patients consumed their usual diet. At these time points, stool and urine samples were collected. Steatorrhea and hyperoxaluria were defined as fecal fat >7 g/day and urine oxalate >40 mg/day. Differences were evaluated using paired 2-tailed t tests. RESULTS: Prior to RYGB, 12 of 26 patients had mild to moderate steatorrhea. Average urine oxalate excretion was 61 mg/day; there was no correlation between fecal fat and urine oxalate excretion. After RYGB, 24 of 26 patients had steatorrhea and urine oxalate excretion averaged 69 mg/day, with a positive correlation between fecal fat and urine oxalate excretions (r = 0.71, P < .001). For each 10 g/day increase in fecal fat output, fecal water excretion increased only 46 mL/day. CONCLUSIONS: Steatorrhea and hyperoxaluria were common in obese patients before bypass, but hyperoxaluria was not caused by excess unabsorbed fatty acids. Hyperphagia, obesity, or metabolic syndrome could have produced this previously unrecognized hyperoxaluric state by stimulating absorption or endogenous synthesis of oxalate. Hyperoxaluria after RYGB correlated with steatorrhea and was presumably caused by excess fatty acids in the intestinal lumen. Because post-bypass steatorrhea caused little increase in fecal water excretion, most patients with steatorrhea did not consider themselves to have diarrhea. Before and after RYGB, high oxalate intake contributed to the severity of hyperoxaluria.

Recycling rate of bile acids in the enterohepatic recirculation as a major determinant of whole body 75SeHCAT retention.

Measurement of the whole body retention of orally administered (75)SeHCAT is used to investigate patients with unexplained diarrhoea. Retention values of <15 % at 7 days post-administration are taken to indicate bile acid malabsorption (BAM). Whilst idiopathic BAM is frequently diagnosed with (75)SeHCAT, functional and morphological studies of the terminal ileum rarely show any abnormality, so the disorder may be more appropriately termed bile acid diarrhoea (BAD). In addition to malabsorption, excess bile acid may reach the colon, where the events leading to diarrhoea take place, as a result firstly of increased bile acid synthesis and secondly of an increased recycling rate of bile acids. Increased recycling has been largely ignored as a cause of BAD, but, as shown in this study, can readily result in excess bile acids reaching the colon even when ileal absorption efficiency is normal (i.e. 95-97 %). There needs to be a re-evaluation of the causes of BAD in patients without a history of previous intestinal resection or evidence of ileal pathology, such as Crohn's disease.

Chylomicron retention disease: report of two cases from a Greek Island.

Chylomicron retention disease (CRD), or Anderson disease, is a rare, hereditary cause of fat malabsorption. It is one of the familial hypocholesterolaemia syndromes, along with homozygous hypobetalipoproteinaemia (HBL) and abetalipoproteinaemia (ABL). We report clinical, laboratory and histological data as well as molecular DNA analysis in the case of a 4-month-old boy with failure to thrive and steatorrhea who was diagnosed with CRD. His mother's first cousin, who was diagnosed as hypobetalipoproteinaemia 30 years ago, was also reviewed and his diagnosis was revised to CRD. Both patients were treated with a low fat diet and supplementation with fat-soluble vitamins resulting in significant improvement. In conclusion, CRD is a well-defined cause of fat malabsorption and can be distinguished from other forms of familial hypocholesterolaemia because of its specific lipid profile.

Anderson's disease/chylomicron retention disease in a Japanese patient with uniparental disomy 7 and a normal SAR1B gene protein coding sequence.

BACKGROUND: Anderson's Disease (AD)/Chylomicron Retention Disease (CMRD) is a rare hereditary hypocholesterolemic disorder characterized by a malabsorption syndrome with steatorrhea, failure to thrive and the absence of chylomicrons and apolipoprotein B48 post-prandially. All patients studied to date exhibit a mutation in the SAR1B gene, which codes for an essential component of the vesicular coat protein complex II (COPII) necessary for endoplasmic reticulum to Golgi transport. We describe here a patient with AD/CMRD, a normal SAR1B gene protein coding sequence and maternal uniparental disomy of chromosome 7 (matUPD7). METHODS AND RESULTS: The patient, one of two siblings of a Japanese family, had diarrhea and steatorrhea beginning at five months of age. There was a white duodenal mucosa upon endoscopy. Light and electron microscopy showed that the intestinal villi were normal but that they had lipid laden enterocytes containing accumulations of lipid droplets in the cytoplasm and lipoprotein-size particles in membrane bound structures. Although there were decreased amounts in plasma of total- and low-density lipoprotein cholesterol, apolipoproteins AI and B and vitamin E levels, the triglycerides were normal, typical of AD/CMRD. The presence of low density lipoproteins and apolipoprotein B in the plasma, although in decreased amounts, ruled out abetalipoproteinemia. The parents were asymptomatic with normal plasma cholesterol levels suggesting a recessive disorder and ruling out familial hypobetalipoproteinemia. Sequencing of genomic DNA showed that the 8 exons of the SAR1B gene were normal. Whole genome SNP analysis and karyotyping revealed matUPD7 with a normal karyotype. In contrast to other cases of AD/CMRD which have shown catch-up growth following vitamin supplementation and a fat restricted diet, our patient exhibits continued growth delay and other aspects of the matUPD7 and Silver-Russell Syndrome phenotypes. CONCLUSIONS: This patient with AD/CMRD has a normal SAR1B gene protein coding sequence which suggests that factors other than the SAR1B protein may be crucial for chylomicron secretion. Further, this patient exhibits matUPD7 with regions of homozygosity which might be useful for elucidating the molecular basis of the defect(s) in this individual. The results provide novel insights into the relation between phenotype and genotype in these diseases and for the mechanisms of secretion in the intestine.

Chylomicron retention disease: a long term study of two cohorts.

Lipoprotein assembly is critical for the intestinal absorption of dietary lipids and of fat-soluble vitamins. Through their inhibition of chylomicron secretion, mutations of the Sar1B gene coding for Sar1 GTPase are associated with chylomicron retention disease (CRD). The aim of this study was to describe the phenotypic expression of CRD in two clinically and genetically well characterized cohorts, and to compare their long term evolution. The study in 7 children from France (X age 11.3+/-1.7 years) and 9 from Quebec, Canada (X age 12+/-2.5 years) involved data collection from medical records for growth evaluation, neurological and ophthalmological status as well as bone density over an average follow-up period of 4.9 years for the French cohort and of 10.6 years for the Canadian one. All CRD patients presented within the first few months of life with diarrhea and failure to thrive. Severe hypocholesterolemia coupled with normal triglycerides was associated with low LDL and HDL-cholesterol, as well as with low apolipoproteins A-I and B. Varying degrees of essential fatty acid and of vitamin E deficiency were observed. The earlier diagnosis in the Canadian cohort (1.3+/-0.04 years) than in the French one (6.3+/-1.3 years) was unrelated with the severity of presenting symptoms. The fact that the disease had more impact on growth and bone density in the latter group may be related to delayed diagnosis of the disease. Vitamin E deficiency led to functional neurological and ophthalmic changes in a small number of patients but only one developed areflexia. Finally, genotype-phenotype correlation is not obvious in our cohort with CRD; even if, the Canadian subjects with the allele 409G>A had a more severe degree (P<0.001) of hypocholesterolemia than the other patients, many clinical data are inconsistent with a hypothetical genotype-phenotype correlation. This study provides new insights on the phenotypic expression of CRD over time and emphasizes the need to screen the lipid profile of infants with chronic diarrhea and failure to thrive.

Fecal elastase1 and acid steatocrit estimation in chronic pancreatitis.

BACKGROUND: Measurement of pancreatic exocrine function and steatorrhea in chronic pancreatitis in the clinical setting has not received much attention. AIM: To assess pancreatic exocrine function and fecal fat excretion in a cohort of patients with chronic pancreatitis. METHODS: Stool elastase1 levels were measured in 101 patients using polyclonal ELISA and acid steatocrit was measured in 86 chronic pancreatitis patients. Associations with etiology, clinical and radiological features, and diabetic status were examined. RESULTS: Low pancreatic stool elastase1 (<200 microg/g stool) was observed in two-thirds of chronic pancreatitis patients and correlated with ductal dilatation, pancreatic atrophy and calcification (p<0.05). Diabetes was more prevalent in chronic pancreatitis patients with low elastase1 (p=0.045). There was no difference in mean acid steatocrit between diabetics and non-diabetics (p=0.069). Elastase1 levels had a negative correlation with acid steatocrit (r=-0.606, p<0.001), and a positive correlation (r=0.412) with body mass index (p=0.013). Fifty-three percent of chronic pancreatitis patients with normal BMI had low elastase1. CONCLUSIONS: Fecal elastase1 levels correlated with fecal fat excretion and BMI. Fecal elastase1 estimation may be helpful in early detection of malabsorption in chronic pancreatitis.

The effect of zinc supplements in cystic fibrosis patients.

AIM: To study the effect of Zn supplements in cystic fibrosis (CF) on disease evolution. METHODS: A retrospective study of all CF patients treated with Zn supplements (January 2002 to December 2004). Data from patient files for the year before and the first year of supplementation were compared. The controls were CF patients with normal serum Zn and without Zn supplementation. RESULTS: 21 patients (7 females), median age 8.9 (interquartile range 13.1) years, received 5 mg/kg Zn sulfate/day (maximum 150 mg). The number of infections decreased from 3 (1.25) to 2 (2.0) (tied p < 0.02) and the forced expiratory volume in 1 s (FEV(1)) increased from 72.0 (38.4) to 76.5 (52)% (p < 0.02). Energy intake improved (92.3 (14.5) to 117.0 (28.5)%; tied p < 0.02), as did weight for height (W/H; 90 (9.4) to 94 (8.5)%; tied p = 0.043). In the CF control patients the number of infections (2.0 (2.0)), energy intake (116 (43.3)%) and nutritional status remained stable (W/H 99 (17.2)%), but pulmonary function decreased significantly (DeltaFEV(1) loss of 2.0 (8.0)%). There was a significantly different evolution for the change in forced vital capacity (p < 0.004) and DeltaFEV(1) (p < 0.001) between supplemented and control patients. CONCLUSIONS: Analysis of the clinical data on Zn supplementation in CF showed beneficial effects in Zn-deficient CF patients. These results must be confirmed in a prospective double-blind randomized control trial.

¿Es la esteatorrea un hallazgo frecuente en pacientes con celiaquia en un hospital de tercer nivel de laciudad de La Paz? / Steatorrhea Is a common finding in patients with celiac disease in a tertiary level city of La Paz?

Pregunta de investigación: Cual será la frecuencia de esteatorrea asociada a celiaquia en pacientes que consultan por diarrea crónica en un Hospital de tercer nivel? Objetivo general: Conocer los aspectos epidemiologicos y clínicos de los pacientes con celiaquia. Objetivos especificos: 1.- Determinar la frecuencia de esteatorrea asociada a enfermedad celiaca.2.- Conocer la correlación del resultado de biopsias del duodeno y las pruebas serológicas especificas de la enfermedad.3.- Determinar la efi cacia del tratamiento dietético en pacientes portadores de esta entidad. Diseño: Serie de casos. Lugar: Instituto de Gastroenterología Boliviano –Japones de la ciudad de La Paz. Participantes Trece pacientes. Metodos: Se estudiaron trece pacientes, ocho mujeres y cinco varones, con un rango de edad de 37 a 68 años. Todos portadores de diarrea crónica.Se les determinó marcadores serológicos específi cos y se les realizó biopsias de duodeno distal. Todos fueron valorados con parâmetros antropométricos al inicio del diagnóstico y seis meses después se correlacionó la respuesta a la dieta sin gluten. Resultados: Los resultados mostraron que la esteatorrea no es el síntoma mas común, los marcadores serológicos de mayor representatividad sonlos anticuerpos antiendomisio y antitransglutaminasa, no así los antigliadina y las biopsias de duodeno demostraron lesiones infiltrativase hiperplasicas, no se evidenció ninguna lesión destructiva. La respuesta a la dieta sin gluten fue en todos los casos favorable y contundente.

Research question: ¿Is the steatorrea the most frecuent sintom in patients with celiac disease at the third level hospital in La Paz city? General objetivs; To identifi ty the epidemiological and clinical caracteristics in patients with celiac disease especific aims: 1.- To identifi ty the esteatorrea frecuency in patients with celiac disease at Instituto de Gastroenterologia Boliviano-Japones in La Paz city. 2.- To establish the correlation betwen the duodenal biopsys and serological test in this illnes.3.- To determine the effectiveness dietoterapic diet in this patients. Desig Serial cases. PlaceInstituto de Gastroenterologia Boliviano Japones at La Paz city. Participants Thirteen patients.Methods: We studied thirteen patients, eight female and fi ve male, 37 to 68 age. All the patients present cronic diarrea. In all we determinate serological marks and duodenal biopsys. We determined antropometric parameters and value the answer the diet without gluten. Results and discusionWe found the esteatorrea isn’t the most sign. The most specifi cal serologycal marks are antiendomisy and antitransglutamins antibodies. Respect to the duodenal biopsys show us infi ltrative and hiperplasic lesions. The diet answer without gluten was in all cases the best answer.

Unresponsive or non-compliant steatorrhea in cystic fibrosis?

In 105 pancreatic insufficient CF patients (steatorrhea and low fecal elastase-1 concentrations), the effectiveness of pancreatic enzyme therapy (PET) has been assessed (fecal fat losses and coefficient of fat reabsorption). Eight unresponsive subjects were checked for PET compliance with fecal chymotrypsin assay. Three patients were documented to be non-compliant. Unresponsive patients should undergo evaluation for PET compliance.

Comparing the urinary pancreolauryl ratio and faecal elastase-1 as indicators of pancreatic insufficiency in clinical practice.

BACKGROUND: The urine pancreolauryl ratio (uPLR) and, more recently, the faecal pancreatic elastase-1, are widely used for the noninvasive diagnosis of exocrine pancreatic insufficiency. Both tests have previously been validated against 'gold standard' tests of pancreatic function, but their use in a clinical setting has never been directly compared. METHODS: We performed a comparative study of the pancreolauryl ratio (PLR) and the faecal elastase-1 (FE-1) test in patients with a clinical suspicion for pancreatic insufficiency. The results were compared with the clinical response to pancreatic enzyme supplementation using pre-defined criteria. RESULTS: Forty-five patients were enrolled in the study and 33 were given a trial of pancreatic enzyme supplementation. Twenty-four out of these 33 showed a positive clinical response to enzyme supplements. Of the 24 responders, 19 had positive FE-1 (<200 microg/g faeces), but only 12 had a positive uPLR (<20). There was a significant correlation between the FE-1 result and clinical response to enzyme supplements (p = 0.01), but not between the PLR and clinical response (p = 0.15). CONCLUSIONS: FE-1 is a simpler test for the patient to perform and more accurately predicts the response to pancreatic enzyme supplementation in patients with chronic, unexplained diarrhoea with a clinical suspicion of pancreatic insufficiency than the PLR. This makes the FE-1 of greater use in clinical practice than the PLR.

[Pathophysiological significance of steatorrhea as well as of hydroxystearic acids in the feces of calves with diarrhea]. / Pathophysiologische Bedeutung von Steatorrhoe sowie von Hydroxystearinsäuren im Kot von Durchfallkälbern.

UNLABELLED: The objective of this study was to determine the digestibility of milk lipids in calves with diarrhoea, the pathophysiological effects of fat intake on the course of the disease and the conversion of malabsorbed longchain fatty acids to secretory effective hydroxy fatty acids by the intestinal flora. ANIMALS: 32 male calves of the breed "Deutsches Fleckvieh" with spontaneous occurring diarrhoea, age 3-14 days. Reference group: 6 clinically healthy calves of the same age group. Feed: whole milk, daily ration corresponding to 10% of the BM, divided into 3 meals; supplementary oral rehydration solution as required. METHODS: Quantitative collection of the faeces excreted over a period of at least 72 hours, determination of fatty acids and glycerides, identification and quantification of hydroxystearic acids in the faeces by gas chromatography; calculation of the apparent digestibility of the milk lipids. RESULTS: The apparent digestibility of the milk lipids was in part considerably reduced in direct relation (r = 0.8) to the severity of the diarrhoea. In the case of daily fecal outputs of over 50 g/kg BM (watery diarrhoea), the apparent fat digestibility was reduced below 50%. Even so, the apparent digestibility correlated positively with the milk intake (r = 0.5). The fat excretion in the patients showed an average of 1.4 g/kg BM/24 h and was thus nearly nine times higher in comparison to the reference group (0.16 g/kg BM/24 h). In the case of severe diarrhoea, fat excretion rates of over 2 (up to max. 5.8) g/kg BM in 24 hours were recorded. However, in the main (approx. 70%) it was not glycerides but nonesterified fatty acids. A part of the longchain fatty acids were converted to hydroxy fatty acids by the intestinal flora. It was possible to quantify alpha-, 10(9)- and 12-hydroxystearic acids individually in the faeces of both healthy calves and those with diarrhoea. However, the total concentration of hydroxystearic acids in the faces of 26 out of 32 patients was considerably under the secretory effective concentration of 2 mmol/kg (mean = 1.5 mmol/kg), the other six lay between 2.9 and 11.6 mmol/kg. Only a weakly positive correlation (r = 0.23 or 0.24) existed between the amount of milk intake and the fecal concentration resp. excretion of hydroxystearic acids. CONCLUSIONS: There was no evidence that the consumption of milk lipids influenced the diarrhoea negatively. In individual cases, it could not be completely excluded that fluid and electrolyte absorption was affected by hydroxystearic acids produced in the intestine, but the quantitative effects of this process are of minor significance in comparison to other diarrhoea inducing factors.

Effect of triglyceride structure on fecal excretion of 13C-labeled triglycerides.

OBJECTIVE: The aim of this work was to determine the effects of specific changes in the structure of (13)C-labeled triglyceride (TG*) on its fecal excretion relative to total stool fat excretion determined simultaneously in patients with reduced exocrine pancreatic function. METHODS: A series of 47 studies were conducted in 26 young cystic fibrosis (CF) patients and 11 adult patients with chronic pancreatitis over a five year period. Each test consisted of ingesting a single high fat test meal containing both (13)C-labeled triglyceride (TG*) and dysprosium chloride (DyCl(3)) a nonabsorbable marker of intestinal transit; in most studies the food colorant brilliant blue (FD&C blue #1) was administered along with the DyCl(3). The TG*s tested were: P*P*P* = TRIPALMITIN-1,1,1-(13)C(3); SO*S = 2-OCTANOYL-1,3-DISTEARIN-2-octanoyl-1,2-(13)C(2); and P*LP* = 2-LAURYL-1,3-DIPALMITIN-dipalmitoyl-1,1,2,2-(13)C(4). Ingestion of the test meal was followed by collection of individual stools for at least 72 hours. Stools were analyzed for (13)C-Excess ((13)C*), total fat, and Dy. RESULTS: Excretion of P*LP* showed a high degree of linear correlation with stool fat (r(2) = 0.924) over a wide-range of fecal fat values. Excretion of SO*S was also significantly correlated with stool fat, but its excretion was less than 10% at all levels of steatorrhea and the slope of the regression line relating TG* excretion to stool fat was some four to five times smaller than observed for P*LP*. Fecal excretion of P*P*P* was highly correlated with stool fat (r(2) = 0.941) in patients with moderate steatorrhea (<25 g fat/24 hours) and the slope of the regression line (3.20) was considerably greater than for P*LP*. Only results from those studies in which stool collections were complete (Dy excretion >90%) were utilized in the statistical comparisons (36 of 47 studies). CONCLUSIONS: The observed highly significant linear correlation between P*LP* and stool fat over the entire range of steatorrhea suggests that P*LP* excretion may be a suitable surrogate for fecal fat in patients with reduced exocrine pancreatic function. Because fecal excretion of TG* administered as described can be accurately determined by sampling only two visually marked stools, development of a noninvasive test to replace the current 72-hour stool fat test using this approach is possible. Use of other engineered TG*s and/or labeled fatty acids, may provide a method for non-invasive in vivo assessment of the specific defect(s) leading to steatorrhea in other patient groups.