Philippe Grandval

Quantitative study of digestive enzyme secretion and gastrointestinal lipolysis in chronic pancreatitis

BACKGROUND & AIMSnThe contribution of human gastric lipase (HGL) to the overall lipolysis process in chronic pancreatitis (CP), as well as the relative pancreatic enzyme levels, rarely are addressed. This study was designed to quantify pancreatic and extrapancreatic enzyme output, activity, and stability in CP patients vs. healthy volunteers.nnnMETHODSnHealthy volunteers (n = 6), mild CP patients (n = 5), and severe (n = 7) CP patients were intubated with gastric and duodenal tubes before the administration of a test meal. HGL, human pancreatic lipase (HPL), chymotrypsin, and amylase concentrations were assessed in gastric and duodenal samples by measuring the respective enzymatic activities. Intragastric and overall lipolysis levels at the angle of Treitz were estimated based on quantitative analysis of lipolysis products. Similar analyses were performed on duodenal contents incubated ex vivo for studying enzyme stability and evolution of lipolysis.nnnRESULTSnAlthough HPL, chymotrypsin, and amylase outputs all were extremely low, HGL outputs in patients with severe CP (46.8 +/- 31.0 mg) were 3-4-fold higher than in healthy controls (13.3 +/- 13.8 mg). Intragastric lipolysis did not increase, however, in patients with severe CP, probably because of the rapid decrease in the pH level of the gastric contents caused by a higher gastric acid secretion. HGL remains active and highly stable in the acidic duodenal contents of CP patients, and, overall, can achieve a significant lipolysis of the dietary triglycerides (30% of the control values) in the absence of HPL.nnnCONCLUSIONSnAlthough all pancreatic enzyme secretions are simultaneously reduced in severe CP, gastric lipase can compensate partly for the loss of pancreatic lipase but not normalize overall lipolytic activity.

Endoscopic treatment of the main pancreatic duct: correlations among morphology, manometry, and clinical follow-up.

SummaryBackground and Aim. During the course of chronic pancreatitis, the gradual increase in the main pancreatic duct pressure is the main pathophysiological factor responsible for pain, but up to now, the intraductal pressure has never been measured during and after endoscopic stenting and correlated with clinical results. Pressure measurements of this kind could thus provide objective information about the useful duration of stenting period.n Methods. Main pancreatic duct pressure was measured by performing endoscopic manometry on 13 chronic pancreatitis symptomatic patients (10 men, 3 women, mean age: 45.1 ± 7.9 yr); clinical follow-up was carried out for a period of 29.0±16.1 mo. Before treatment, the main anatomical alteration present was a localized stenosis of the main pancreatic duct, i.e., one with a diameter of less than 2 mm (chronic pancreatitis alone), 10 cases; chronic pancreatitis associated with pancreas divisum, 3 cases). Stenosis was treated by endoscopic stenting: 7 F stent (7 cases) and 12 F stent (6 cases). The pressure was measured simultaneously in the duodenum (zero level) and within the main pancreatic duct, using an electronic device. The pancreatico-duodenal gradient was taken to be the difference between the pressure in the main pancreatic duct and the duodenum.n Results. The endoscopic stenting induced a nonsignificant decrease in the intraductal pressure (p=0.16). Among the 9 patients with a normal pressure at the end of the stenting and a successful anatomical outcome, 6 were painless during the follow-up period whereas 3 presented with recurrent pancreatic-type pain. The remaining 4 patients were symptom-free during the entire follow-up period, although the main pancreatic duct pressure was high at the end of the stenting and the stenosis was not completely cured.Conclusion. The intraductal pressure at the end of the stenting period was perfectly correlated with the anatomical result, whether or not it was successful, but was not an accurate predictor of a favorable clinical outcome in patients with a poor anatomical result.

Effects of Lansoprazole on Human Gastric Lipase Secretion and Intragastric Lipolysis in Healthy Human Volunteers

Background: Lansoprazole is a potent proton-pump inhibitor (PPI) of parietal cells, which reduces the secretion of gastric acid. Although human gastric lipase (HGL) is produced only by the chief cells of the stomach, the possibility that interactions may occur between lansoprazole and HGL has never been addressed so far in humans. The aim of this study was therefore to quantify the effects of lansoprazole on HGL secretion and intragastric lipolysis during the ingestion of test meals by healthy human volunteers. Methods: Six healthy volunteers were intubated twice with a gastric and a duodenal tube, before ingesting a standard liquid test meal alone (–PPI experiments) and after 7 days of lansoprazole treatment (+PPI experiments). The HGL concentration was assessed in gastric and duodenal samples by measuring the lipase activity using a pH-stat, and the lipolysis products were quantified by performing thin layer chromatography. The level of intragastric lipolysis was defined as the percentage acyl chains released from the meal triglycerides. The pyloric outputs of HGL and lipolysis products were calculated, based on the use of a non-absorbable marker added to the meal. Results: The pH of the gastric contents was significantly higher in the +PPI experiments than in the –PPI experiments (p < 0.05), since mean values of 4.3 ± 2.5 and 2.2 ± 1.6, respectively, were recorded at the end of the gastric emptying of the meal. The HGL concentrations recorded during the meal were found to be higher in the experiments with lansoprazole (p < 0.05) than in those without lansopra- zole, but the HGL secretion levels (–PPI: 15.4 ± 8.0 mg; +PPI: 19.0 ± 7.4 mg) and the intragastric lipolysis (–PPI: 24.0 ± 8.0%; +PPI: 23.6 ± 6.8%) were not significantly affected by lansoprazole (p > 0.05 in both cases). Conclusion: Lansoprazole affected neither the HGL secretion nor the intragastric lipolysis levels, although an increase was observed in the intragastric pH at the end of the gastric emptying of the meal. The HGL concentration increased, however, due to the decrease in the acid secretion process, resulting in less diluted gastric contents.

Advantage of Expressing the Variations in Some Digestive Parameters as a Function of Gastric Emptying instead of Time

Background/Aim: Gastric emptying is a major cause of variability when studying gastrointestinal parameters as a function of time. Here, we investigate whether the parametric variability could be reduced by running experiments on a gastric emptying basis rather than on a time basis. Methods: Healthy volunteers were intubated with gastric and duodenal tubes and were given a liquid meal containing polyethylene glycol to monitor gastric emptying. Gastric pH and human gastric lipase (HGL) concentrations were measured. Their variations were plotted as a function of either time or gastric emptying (%). In both cases, mean curves of variation were established by polynomial regression. Results: When time was the variable used, the overall deviation of the experimental values from the values given by the best-fitting curve was high (χ2 = 33 for gastric pH; χ2 = 1,744 for HGL), and the individual deviations increased with time. When gastric emptying was the variable used, the overall deviation of the experimental values from the values given by the best-fitting curve was much lower (χ2 = 10 for gastric pH; χ2 = 642 for HGL). Conclusions: Expressing gastric pH or HGL concentration as a function of gastric emptying instead of time makes it possible to reduce the individual variability. This new type of data analysis may be of a general interest to observe specific variations of gastrointestinal parameters induced by drugs, hormones, and meals, and that might be masked by the large intrinsic variability induced by gastric emptying.

Interventional treatment of chronic pancreatitis.

Endoscopic treatment of chronic pancreatitis is becoming a reality: more and more endoscopy centres are developing the technique, and it is no longer a matter of extreme specialization. Among treatments which have been shown to be feasible, it is possible to distinguish between those approaches that are now considered as efficient with good results and very low risk (e.g. MPD drainage), or are efficient but with risks that seem to be lower than those of surgery (e.g. drainage of cysts), and drainage of the main bile duct, which is easy to perform, but, so far, has not been demonstrated enough as useful.

Critical evaluation of a specific ELISA and two enzymatic assays of pancreatic lipases in human sera

Background and Aims: Human pancreatic lipases (HPL) include the classical HPL, and two related proteins known as pancreatic lipase-related proteins 1 and 2 (HPLRP1 and 2). The aim of this study was to develop an ELISA for specifically quantifying the classical-HPL level in sera of patients with and without pancreatic disorders. Methods: The specific activity of various human (including classical-HPL) and microbial lipases was measured using Lipa Vitros and potentiometric (pH-stat) assays. A double sandwich ELISA was also set up, using an anti-classical-HPL polyclonal antibody and a biotinylated monoclonal antibody (mAb 146-40) specific to the classical-HPL. Sera (n = 53) were collected from patients with and without pancreatic disorders. The lipase concentration was deduced from the measured lipolytic activity and compared with the corresponding classical-HPL concentration, measured with the ELISA. Results: Both the purified HPLRP2 and 3 lipases of microbial origin were found to have a significant and unexpected lipolytic activity under the standard Lipa Vitros assay, whereas the ELISA test developed in the present study was found to be specific for the classical-HPL, due to the absence of cross-reactivity between mAb 146-40, HPLRP1 and HPLRP2. The efficiency of the ELISA was assessed in terms of its reproducibility and accuracy. The lower detection limit of classical-HPL was found to be 0.03 µg/l. A good correlation was found to exist between the lipase concentrations obtained in the ELISA, pH-stat and Lipa Vitros tests, in both the control and pathological groups. Conclusion: This is the first time a specific method of measuring classical-HPL in human serum has been proposed. Using this ELISA, we established with the 53 sera selected in the present study, that the Lipa Vitros assay as well as the pH-stat assay were mostly detecting classical pancreatic lipase. However, it is possible that other lipases such as HPLRP2 or lipases of microbial origin, present in some pathological sera, may well interfere with the Lipa Vitros assay.

Influence of lansoprazole on the human gastric lipase and the intragastric lipolysis in healthy volunteers

The role of Lewis antigens in the pathogenic process is not well understood. The aim of this study was to determine whether the Lewis antigen expression of H. pylori differed in isolates obtained from symptomatic and asymptomatic individuals. Lewis antigen expression status was determined by ELISA, and confirmation of LPS 0 side chain production in isolates not expressing Lewis antigen phenotype was conducted by SDS-PAGE. Expression of Lewis antigens by H. pylori isolates of symptomatic and asymptomatic individuals differed significantly in three main categories: I) Type I Lewis antigens (Lea and Le) were not expressed at all by isolates from asymptomatic individuals, as compared with low level expression by isolates from symptomatic individuals; 2)incidence of LeX expression was significantly reduced in isolates from asymptomatic individuals; 3) an increased proportion of isolates from asymptomatic individuals did not express any Lewis antigens at all. The identification of differences between H. pylori isolated from symptomatic and asymptomatic individuals is the first step to understanding the potential role Lewis antigens may play in the pathogenicity of this bacteria. The decrease in the LeX expression by isolates from asymptomatic individuals is particularly interesting as this antigen has been noted to be expressed in higher proportions of H. pylori isolated from patients with peptic ulcer disease. The isolation of a high proportion of H. pylori that do not express any Lewis antigens in asymptomatic strains may also indicate a host-mediated cross reaction to the H. pylori Lewis antigens that may cause the pathology seen in some symptomatic patients.