A 2 7 0 AGA ABSTRACTS GASTROENTEROLOGY, Vol. 108, No. 4

• t3C HIOLEIN/NEOLATE BREATH TEST FOR FAT MALDIGESTION/ M A L A B S O R P T I O N - FINALLY A FAT BREATH TEST THAT WORKSl S.T. Amann~ M. Cintron, C. Curington, W. Ronsh, M. Bishop, P.P. Toskas. University of Florida, Gainesvile, FL. Previous fat breath tests have been a disappointment because they were only able to accurately detect severe degrees of stsatorrhea and only after many patients had been excluded. A 13C I-Iiolein (I-IBT) and 13C Neolate (NBT) breath test may be a practical and distinguishing test for steatorrhea. Hiolein, a neutral triglyceride obtained from algae, and neolate, fatty acids liberated from the hydrolysis of hiolein, were obtained from Martek Biosciences. These substrates were diffusely labeled with 13C (non-radioactive isotope), enriched by 98% and supplied in corn oil. AIMS: 1) To determine the reproducibility of the HBT and its ability to detect steatorrlisa. 2) To determine if the NBT can reliably distinguish between pancreatic steatorrhea and small bowel steatorrhea. METHODS: 22 subjects with varying degrees of fat absorption, (5 chronic pancreatitics with insufficiency - PI, 3 patients with short gut - SG, and 14 healthy controls) underwent the following tests: 1) on a standard diet, a NBT and I-IBT; and 2) on a high fat diet (100g fat/day), a 72 hr. fecal fat (FF), an NBT, 2 HBT, and a corn oil alone BT. All breath tests were administered as 2mg/kg with a 60g. carrier fat. A baseline breath sample was obtained, substrate and carrier fat given, and samples collected every hr. for 12 hrs. Breath tests were separated by 40 hrs. Samples were analyzed (Metabolic Solutions) and reported as % ~3CO2 excess above baseline x 1000. RESULTS: FF (nl<7g/24hr) demonstrated steatorrhea in all PI (m=26g/24hr) and SG (m=50g/24hr). FF in healthy controls was (m=3g/24hr). Peak values during the breath test occurred at 9 and 10 hrs. with 10 hrs. being slightly better. Comparison between groups was therefore ca~ed out at 10 hrs. There was no difference between HBT or NBT when performed on and off the 100g fat diet. Cumulative curves added no discriminatory benefit. The HBT showed a significant difference between all steaterrhsa (PI+SG) (mf17.01±16.58SD) and controls (mffi56.09±14.16SD). The NBT showed a significant difference between PI (mf31.13±17.10SD) and SG (m=4.10±3.64SD). There was no significant difference between the 2 HBT for reproducibility (m1=53.21±19.77SD vs m2=56.84±12.34SD). CONCLUSIONS: Using highly enriched (98%) substrates and a high carrier fat (60g) on subjects with varying degrees of fat absorption, we were able to conclude: 1) HBT has good reproducibility, 2) In both HBT and NBT, high fat vs. standard diet did not alter the assay, 3) FIBT and NBT used together appear to be useful for the diagnosis and differentiation of steatorrhea. Unlike previous experiences with fat breath tests, this study suggests that a 13C Hiolaln/Nsolate breath test will be a practical and distinguishing test for steatorrhea.

• CHARACTERIZATION OF A NOVEL VILLUS CELL POPULATION WITH HIGH LEVELS OF APICAL AND INTRACELLULAR CFI 'R EXPRESSION. N.A. Ameen I, P. Peters 2 and C.R. Marino3. Depts. of Pediatrics 1 and Medicine 3, Yale U. School of Medicine, New Haven, CT, and Dept. of Cell Biology 2, U. of Utrecht School of Medicine, The Netherlands.

Intestinal disease in cystic fibrosis is manifested by mechanical small bowel obstruction caused by viscous luminal contents. Defective function of cP ' rR , a cAMP-activated chloride channel, is believed to underlie the pathophysiology of this process. Although crypt cells are a recognized site of CFTR expression and chloride secretion in the intestine, recent in situ hybridization data indicates that some rat and human small intestinal villus cells also express CFTR. The aim of the current study was to use immunocytochemical techniques to examine the distribution, morphology, and function of these CPTR-expressing villus cells. Immunofluorescence and c ryo immunogo ld electron mic roscopy were per formed using antibodies against CFTR and other plasma membrane markers. In the proximal small intestine of the rat, approximately 3% of villus epithelial ceils label brightly with anti-CFTR antibodies. These CFTR-expressing villus cells, also seen in the human small intestine, extend from the gut lumen to the lamina propda. They are distinguished by their lack of expression of the brush border enzymes sucrase and lactase, markers of absorptive villus enterocytes. They do, however, resemble neighboring villus ceils in their basolateral membrane expression of Na+-K+-ATPase. Uhrastructural ly, the CFTR-expressing villus cells possess a slightly disordered brush border, an abundance of mitochor~dria, and a prominent subapicat vesicular compartment. They are devoid of electron dense secretory granules. Immunofluorescence labeling for CFTR is readily detected throughout these cells, with greatest concentration at the apical pole. Immunogold labeling reveals high levels of CPTR expression on the apical plasma membrane of the microvilli. Immunogold labeling of coated pits and coated vesicles is also seen. The detection of CPTR within coated pits and membrane-bound structures resembling clathrin-coated vesicles suggests that CFTR is associated with regulated endosornal trafficking and plasma membrane recycling. In conclusion, a novel subpopulation of villus enterocytes with apical membrane and intracellular CFTR expression exists in the rat and human small intestine. Cytochemical studies indicate that these villus enterocytes are unique in that they appear to have a non- absorptive transport function. Their role in intestinal chloride transport physiology and CF pathophysiology is yet to be determined.

• CARRIER MEDIATED ABSORPTION OF CONJUGATED BILE ACIDS IN THE JEJUNUM OF GUINEA PIGS: A. Amelsberg, C.D. Schteingart, A.F. Hofmann. Department of Medicine, University of Kiel, Germany, and Division of Gastroenterology, University of California San Diego.

Numerous studies indicate appreciable absorption of conjugated bile acids from the jejunum in mammals including man, but the mechanism has not been clarified. Glycine conjugated bile acids with a pKa of 3.9 can be protonated and absorbed passively in this form (GE 106:A219 1994), but taurine conjugated bile acids being strong acids must be absorbed as anions. Experiments were performed to test whether a carrier mechanism is involved in the absorption of taurine conjugated bile acids in the guinea pig. 14C and SH tagged taurine conjugated bile acids were synthesized and their absorption rate measured using the perfused jejunum in biliary fistula animals; absorption was equated with biliary recovery. In i t ia l rate of uptake (nmollmg protein-min) by isolated jejunal enterocytes was also quantified. Results: The P=. [absorption rate/ area/conc. (0.5 mM); units, 10 s cm/sec; M+S~M] was greater for dihydroxy taurine conjuga- tes than cholyltaurine (CDC-tau, 7.3+0.3; DC-tau, 5.2+0.6; UDC- tau, 5.0+0.4; C-tau, 2.8+0.3 p's<0.05). CDC-tau and DC-tau but not taurine inhibited absorption of UDC-tau. UDC-tau absorption showed saturation at high UDC-tau absorption rates. With isolated enterocytes, initial rate of uptake (at 0.2 mM bile acid conc.) of dihydroxy bile acids was greater than that of C-tau (CDC-tau, 6.1+1.1; UDC-tau, 2.1+0.1; C-tau, 1.4+0.2 p's<0.005). Competitive inhibition of UDC-tau uptake by CDC-tau was shown, as well as decreased uptake of UDC-tau at 4°C. Uptake of UDC- tau was uninfluenced by the presence of Na*, Conclusions: Taurine conjugated bile acids are absorbed slowly from the guinea pig jejunum by a Na ÷ independent ca r r i e r mediated mechanism. The mechanism is likely to be facilitated diffusion and/or an anion exchange process. Carrier mediated absorption together with passive absorption of protonated glycine conjugated bile acids provides an explanation for jejunal uptake of conjugated bile acids in mammals.

AUDIT OF UPPER GASTROINTESTINAL HAEMORRHAGE: THE EFFECTS OF A PROTOCOL AND EDUCATION J.T. Anderson D.A. Johnston, A. Mulroy, F.E. Murray. Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland. DD1 9SY.

Background: Upper gastrointestinal haemorrhage is a cause of significant mortality in acute medical admissions. Recently guidelines have been published on the management of acute upper gastrointestinal haemorrhage. Based on these guidelines we have introduced a protocol for the management of acute upper gastrointestinal haemorrhage and initiated a teaching programme for Junior Residents. Aims: The aim of this audit was to monitor the effects of the introduction of the protocol, and the teaching programme, on the management Of acute upper gastrointestinalhaemorrhage in Ninewells Hospital. Patients and Methods: All patients admitted to hospital with a history of acute haematemesis Or melaena were included in th e study. Purpose designed audit forms were completed on all patients to determine patient demographics, initial clinical status, time to endoscopy, and subsequent diagnosis, endoscopic intervention, and outcome. Following an initial 6 month audit period, the protocol and teaching were introduced, and a further 6 months audit was then performed. Results: in two six month periods a total of 310 patients were audited. There was no statistical difference in the age sex, initial clinical status of the patients, number of endoscopies performed, and diagnoses, between the two audit periods. The most common diagnosis were peptic ulcer disease (37.2%) and ulcerative oesophagltis (15.6%). Following the introduction of the protocol and teaching programme there was an increase in the percentage of people undergoing early endoscopy from 86.8% to 93.9%. There was an increase in the number of people receiving appropriate interventional endoscopy (p = 0.032). There was a more appropriate referral pattern for out of hours endoscopy, and a decrease in the number performed (18.6 to 13.0%). There was no change in the rebleeding rate or in the number of patients requiring emergency surgery. The mortality rate was low and unchanged in both audit periods at just above 4%. Conclusion: These results suggest that the introduction of a protocol, in addition to staff education and training, increased the rate of endoscopic intervention, and decreased the out of hours endoscopy requirement.