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Effect of different immunosuppressive agents on acute pancreatitis: a comparative study in an improved animal model.

BACKGROUND: Immunosuppressive drugs have been associated with the development and progression of acute pancreatitis after organ transplantation. Consequently, a reduction or a change in immunosuppressive therapy has been recommended once posttransplantation pancreatitis has been suspected. However, it is not known which of the available immunosuppressive agents is most harmful to the pancreas and which may be used safely in this situation. The objective of this study was to investigate the effect of different immunosuppressive drugs in various dosages on intrapancreatic protease activation, acinar cell necrosis, and mortality in an improved model of acute necrotizing pancreatitis in the rat. The rat model of acute necrotizing pancreatitis, like posttransplantation pancreatitis, is characterized by ischemia and microcirculatory disorders. METHOD: Acute pancreatitis was induced in rats by using a combination of low-dose controlled intraductal glycodeoxycholic acid superimposed on intravenous cerulein hyperstimulation. Six hours thereafter, animals were randomized to intravenous therapy with 2, 10, or 50 mg/kg/day prednisolone (PRED); 3, 15, or 60 mg/kg/day cyclosporine A (CsA); 10 mg/kg/day azathioprine (AZA); 0.6 mg/kg/day orthoclone OKT3 (OKT3); or saline. After 36 hr, surviving animals were killed to determine acinar cell necrosis and trypsinogen activation peptides levels (TAP) in blood and ascites. RESULTS: Compared with saline-treated control rats, animals treated with 60 mg/kg/day CsA developed significantly more acinar cell necrosis and had increased amounts of TAP in ascites. Likewise, there was more extensive acinar cell necrosis in animals subjected to AZA therapy. However, this was not associated with incremental TAP. Animals treated with 3 or 15 mg/kg/day CsA, OKT3, or PRED showed no significant changes in these target parameters. Animals given 10 or 50 mg/kg/day PRED even had decreased hematocrit values and produced significantly less ascites than animals in the other groups. CONCLUSION: The present results suggest that AZA and high doses of CsA aggravate acute pancreatitis and should, therefore, be avoided once posttransplantation pancreatitis has been suspected, whereas lower doses of CsA, OKT3, and PRED may be used safely. PRED can even be used at higher doses as may be required when graft rejection is suspected.

Acute Disease↗

Bile acids in xenogeneic ex-vivo liver perfusion: function of xenoperfused livers and compatibility with human bile salts and porcine livers.

BACKGROUND: In recent years, hepatic support systems using xenogeneic cells have been developed to support patients in fulminant hepatic failure. The extent to which xenogeneic hepatocytes metabolize and excrete human organic anions is unclear. In these studies we examined the ability of the ex vivo porcine liver to clear human bile acids during extracorporeal liver perfusion (ELP). METHODS: Four patients with fulminant hepatic failure underwent extracorporeal liver perfusion with 9 porcine livers. The venovenous circuit was designed as previously described (NEJM,1994,331:234) as were the immunologic features (Transplantation 1994,58:1162). Bile from the porcine liver and serum samples were collected hourly during perfusion. Three bile acids (glycocholic, glycodeoxycholic, taurodeoxycholic acid) were selected as markers for human bile and three (glycohyocholic, glycohyodeoxycholic, and glyco-3alpha-hydroxy-6-oxo-5beta-cholanoic acid) for markers of pig bile. Bile acids from both serum and bile were processed and analyzed through high performance liquid chromatography. The Students' t test was used for statistical analysis. RESULTS: The mean duration of perfusions was 4.1+/-1.5 hr. The mean total bile acid clearance from serum (243+/-44 micromol/h) was similar to the total bile acid biliary excretion (286+/-84 micromol/hr, P = 0.06). After 1 hr of perfusion, bile samples demonstrated a predominance of pig bile salts (65%). After 3 hr of perfusion, human bile acids made up 85% of total biliary bile acids. Pig bile acids appeared in patients' sera after 1 hr of perfusion, and after 3 hr, 35% of serum bile salts were pig-specific. CONCLUSIONS: Porcine livers perfused with human blood can clear the serum of potentially toxic human bile acids and excrete them into bile. Simultaneously, the percentage of pig-specific bile acids in patient serum increases during xenogeneic perfusion for unknown reasons. The relative hepatic uptake of bile acid from serum is similar to bile acid excretion in bile. Further development of systems using porcine livers or hepatocytes is warranted.

Animals↗

Steroid metabolism along the gastrointestinal tract of the cannulated pig.

Steroid metabolism along the gastrointestinal tract of the cannulated pig was studied. Thi was achieved by fitting simple gut cannulas in the terminal ileum, caecum and mid-colon of three Landrace x large white boars, which enabled convenient collection of digesta and faecal samples at defined time points. Biochemical analyses showed that the neutral steroid profile of the pig is similar to that of man, dominated by cholesterol and its bacterial metabolite coprostanol. In contrast, pigs consuming a normal diet excrete appreciably lower quantities of neutral sterols in faeces. The major primary bile acids detected were the glycine and taurine amidates of hyocholic and chenodeoxycholic acids, which were rapidly converted to the free bile acids and subsequently dehydroxylated to hyodeoxycholic and lithocholic acids respectively, in the terminal ileum and caecum. Bacterial deconjugation and 7 alpha-dehyrdoxylation are virtually complete in the caecum with negligible further metabolism in the colon and faeces. On a wet weight basis the concentration of both neutral and acid steroids was shown to increase aborally. Inclusion of dietary fibre in the form of cellulose (Solka floc) and guar gum reduced steroid concentration considerably at all sites of the large intestine, which is consistent with their stool bulking effects. In conclusion, this study shows that intestinal steroid metabolism in the pig is similar to that in man despite slightly different bile acid profiles and, therefore, the multicannulated pig may serve as a useful model of man in chemoprevention studies of colorectal cancer.

Animals↗

Effects of subtotal colectomy on bacterial translocation during experimental acute pancreatitis.

OBJECTIVES: The colon is considered a major source of bacteria causing infection of pancreatic necrosis in acute pancreatitis (AP). Subtotal colectomy before AP in rats reduces mortality, but its role in affecting small bowel flora, bacterial translocation, and infection of pancreatic necrosis is unknown. Our aim was to study these phenomena in rats with AP. METHODS: Fifty rats, allocated in 4 groups, underwent 2 laparotomies: group 1, sham laparotomy and saline biliopancreatic duct infusion; group 2, subtotal colectomy and saline infusion; group 3, sham laparotomy and AP (ductal infusion of glycodeoxycholic acid and intravenous cerulein); group 4, subtotal colectomy and AP. Seventy-two hours later, samples were collected for microbiological analysis. RESULTS: Subtotal colectomy caused small bowel bacterial overgrowth with gram-positive cocci (group 1 versus group 2, duodenum: P = 0.030, ileum: P = 0.029). Bacterial counts of gram-negative rods/anaerobes in the duodenum and ileum and pancreatic bacterial counts of rats with colectomy and AP were significantly higher than in rats with AP only (group 3 versus group 4, duodenum: P = 0.040, ileum: P = 0.029, pancreas: P = 0.017). Duodenal bacterial overgrowth and pancreatic infection correlate significantly (r = 0.45, P = 0.004). CONCLUSIONS: Subtotal colectomy induces small bowel bacterial overgrowth, which is associated with increased bacterial translocation to the pancreas.

Acute Disease↗

Significance of bile salt hydrolytic activities of lactobacilli.

Bile salt hydrolase (BSH) activity was shown to be constitutive and substrate-specific: the BSH isogenic Lactobacillus plantarum wild type (LP80 WT) and BSH overproducing LP80 (pCBH1) strains preferentially hydrolysed glycodeoxycholic acid (GDCA), whereas the hamster Lact. animalis isolates H362 and H364 showed a higher affinity for taurodeoxycholic acid (TDCA). In viability studies in the presence of nutrients, it was demonstrated that GDCA exerted a higher toxicity than TDCA in a pH-dependent manner. This toxicity was inversely proportionate to the BSH activity level of the strains tested, indicating that BSH activity contributed towards bile salt resistance when appropriate nutrients were available. The high toxicity of GDCA relative to TDCA was suggested to be caused by their weak and strong acid properties respectively. It was therefore hypothesized that the protonated form of bile salts exhibited toxicity as it imported protons in the cell. This puts an energy-burden on BSH- lactobacilli which undergo intracellular acidification. BSH+ cells primarily protect themselves through the formation of the weaker DCA compound, which can help negate the pH-drop by recapturing and exporting the co-transported proton. However, since DCA is more toxic than its conjugated counterparts, an additional energy-dependent detoxification of DCA is suggested.

Animals↗

Unconjugated, glycine-conjugated, taurine-conjugated bile acid nonsulfates and sulfates in urine of young infants with cholestasis.

A direct assay system for conjugated bile acids using an enzymatic procedure and high-performance liquid chromatography was used for the analysis of urinary bile acid profiles in young infants with intrahepatic cholestasis (idiopathic neonatal hepatitis syndrome) or extra-hepatic biliary atresia. The major urinary bile acids were cholate and chenodeoxycholate conjugates, but a small amount of deoxycholate and 3 beta-hydroxy-5-cholenate conjugates were detected. Although there was no significant difference in total bile acid excretion between patients with intrahepatic cholestasis and extrahepatic biliary atresia, mean ratios of cholate to chenodeoxycholate and sulfated to total urinary bile acids were different between the two groups examined (5.63 +/- 2.83 vs. 2.50 +/- 1.25, p less than 0.05, 15.8 +/- 9.9 vs. 34.5 +/- 9.9%, p less than 0.005). The proportion of taurine-conjugated chenodeoxycholate in the sulfate fraction to the total bile acid was lower in intrahepatic cholestasis, compared with that in biliary atresia (7.7 +/- 7.5 vs 22.7% +/- 7.8%, p less than 0.005). The greater ratio of cholate to chenodeoxycholate and the reduced excretion of sulfated urinary bile acids in intrahepatic cholestasis was due to decreased taurine-conjugated chenodeoxycholate sulfate excretion.

Bile Acids and Salts↗

Transformation of bile acids by Clostridium perfringens.

Thirty-five strains of Clostridium perfringens were examined for their ability to transform bile acids, both in growing cultures and by washed whole cells. All of the strains oxidized the 3 alpha-hydroxy group to an oxo group, and all except three converted the same alpha-hydroxy group into a beta-configuration. The oxidative 3 alpha-dehydrogenation was barely detectable under anaerobic cultural conditions but was clearly demonstrated in an aerated system using washed whole cells, with a pH optimum between 7.0 and 9.0. The epimerizing reaction amounting to 10 to 20% conversion was observed in anaerobic cultures and also with resting cells, irrespective of oxygen supply. Both reactions were carried out with seven conventional 3 alpha-hydroxy bile acids, thus producing a series of 3-oxo and 3 beta-hydroxy derivatives that could be examined for gas-liquid chromatographic and mass spectrometric behavior. No evidence for the occurrence of 7 alpha- and 12 alpha-hydroxysteroid dehydrogenase activities among the test strains was found. A highly potent deconjugating hydrolase was elaborated by all of the strains.

Aerobiosis↗

Influence of changes in pancreatic tissue morphology and capillary blood flow on antibiotic tissue concentrations in the pancreas during the progression of acute pancreatitis.

BACKGROUND: The ability of an antibiotic to reach bactericidal concentrations in tissue depends on numerous factors including tissue composition and regional perfusion. Although necrotising pancreatitis is characterised by progression of pancreatic necrosis over at least 96 hours and microcirculatory alterations, the impact of these changes on the concentration of antibiotics in the pancreas has not yet been investigated. AIM: To determine and compare pancreatic tissue concentrations of imipenem and cefotaxime at different stages of acute necrotising pancreatitis in an animal model that has been shown to mimic closely the pathomorphological and bacteriological features of severe human pancreatitis. METHOD: Acute necrotising pancreatitis was induced in rats by a standardised intraductal infusion of glycodeoxycholic acid and intravenous cerulein. Six hours (n = 16) and 48 hours (n = 16) after induction of pancreatitis, the animals were randomised for intravenous therapy with either imipenem or cefotaxime. Fifteen minutes after injection of the antibiotic, the animals were killed. Blood and the head of the pancreas were collected for determining imipenem or cefotaxime in serum and tissue; the splenic portion of the pancreas was prepared for histological examination. In an additional set of identically treated animals, pancreatic capillary blood flow (PCBF) was assessed by intravital microscopy before induction of acute necrotising pancreatitis and at the time of antibiotic therapy. RESULTS: Imipenem accumulates in the pancreas in the initial phase of acute necrotising pancreatitis characterised by pronounced oedema and decreased PCBF, and tends to decrease with resolution of the oedema and the progression of acinar cell necrosis in the later course of the disease. Concentrations of cefotaxime are low in oedematous pancreatic tissue early after induction of acute necrotising pancreatitis and increase with the resolution of oedema and normalisation of PCBF. CONCLUSIONS: Concentrations of antibiotics in the pancreas vary in acute necrotising pancreatitis, depending on changes in pancreatic tissue morphology and capillary blood flow. This suggests that antibiotic tissue concentrations may not be consistent from one agent to another and that efficacy of antibiotics in acute pancreatitis cannot be estimated solely on the basis of their pharmacological and microbiological properties.

Acute Disease↗

Pulmonary microcirculation in mild and severe experimental pancreatitis.

BACKGROUND: Research aimed at elucidating the pathogenesis of pancreatitis-associated lung injury and evaluating novel strategies for preventing respiratory complications in acute pancreatitis (AP) has not yet involved intravital microscopic (IVM) studies of pulmonary microcirculation in animals with severe disease. OBJECTIVE: To characterize and compare pulmonary microcirculation in severe/necrotizing (NP) and mild/edematous pancreatitis (EP) in the rat. METHODS: EP was induced by intravenous cerulein infusion (n = 10) and NP by a standardized intraductal infusion of glycodeoxycholic acid followed by intravenous cerulein (n = 10). After 24 h a left-sided thoracotomy was performed for IVM examination of pulmonary capillary blood flow, permeability, leukocyte sticking and the thickness of alveolar septi. Further measurements included monitoring of arterial blood gases and histological evaluation of lung injury. RESULTS: In animals with NP, histology revealed severe pulmonary edema together with clustering of polymorphonuclear leukocytes in pulmonary microvessels and alveoli. IVM showed a greater number (n) of leukocytes sticking on the endothelium of pulmonary capillaries (9.4 +/- 0.7 vs. 1.8 +/- 0.2 in healthy control animals) and increased capillary permeability (260 +/- 14 vs. 136 +/- 6% relative fluorescein intensity) while capillary blood flow was decreased (0.41 +/- 0.05 vs. 0.57 +/- 0.03 mm/s). In comparison, changes in EP were significantly less pronounced (flow 0.5 +/- 0.04 mm/s, permeability 156 +/- 4%, leukocyte sticking n = 4.6 +/- 0.7). CONCLUSIONS: These findings suggest that deterioration of pulmonary microcirculation in AP correlates with disease severity and that a model featuring NP may therefore be more suitable to further study pancreatitis-associated pulmonary injury.

Animals↗

Degradation and inactivation of plasma tumor necrosis factor-alpha by pancreatic proteases in experimental acute pancreatitis.

BACKGROUND: Release of TNFalpha is thought to play an important role in mediating systemic effects in acute pancreatitis (AP). We have been unable to find an elevation of plasma TNFalpha in AP and hypothesize that it is susceptible to catabolism by circulating pancreatic proteases. METHODS: (1) AP was induced in Sprague-Dawley rats by cerulein hyperstimulation preceded by intraductal infusion of saline (mild) or glycodeoxycholic acid (severe). Healthy and sham-operated animals served as controls. Severity of pancreatitis was confirmed by histology. Plasma TNFalpha levels were measured at various time points after induction of AP with competitive ELISA. (2) Recombinant rat TNFalpha (rrTNFalpha) was incubated with trypsin, elastase, chymotrypsin and pepsin. Western Blot was performed to visualize TNF degradation. (3) RrTNFalpha was incubated in a concentration and time-dependant manner with proteases and TNF bioactivity was evaluated with a cytotoxicity assay. RESULTS: (1) Plasma TNFalpha levels in severe pancreatitis were significantly lower than in sham-operated controls after 0.5 and 6 h. (2) Incubation with proteases showed degradation in the presence of trypsin, elastase and chymotrypsin and no effect of pepsin. (3) There was a concentration dependent inactivation of rrTNFalpha in the presence of pancreatic proteases and a complete time-dependent inactivation in the presence of trypsin. CONCLUSION: Plasma TNFalpha does not rise in experimental AP, and levels are significantly lower in severe pancreatitis compared to sham-operated controls. Our study demonstrates degradation and inactivation of TNFalpha by pancreatic proteases, suggesting that it is unlikely it plays an important role in the development of distant organ failure.

Acute Disease↗

Improvement of impaired microcirculation and tissue oxygenation by hemodilution with hydroxyethyl starch plus cell-free hemoglobin in acute porcine pancreatitis.

AIMS: To avoid the progression from mild edematous acute pancreatitis (AP) to the severe necrotizing form, one therapeutic option is to improve pancreatic microcirculation and tissue oxygenation. The aim of the study was to evaluate the influence of improved rheology (isovolemic hemodilution) plus enhanced oxygen supply (bovine hemoglobin HBOC-301) on pancreatic microcirculation, tissue oxygenation and survival in severe acute experimental pancreatitis. METHODS: Severe AP was induced in 39 pigs (25-30 kg BW) by stimulation with intravenous administration of cerulein plus a pressure- and volume-controlled 10-min intraductal infusion of glycodeoxycholic acid. Seventy-five minutes after induction of AP, animals were randomized and hemodiluted isovolemically (PAOP constant) with either 10% hydroxyethyl starch (HES) 200,000/0.5 plus HBOC-301 (+0.6 g/dl plasmatic hemoglobin; Oxyglobin, Biopure, Cambridge, Mass., USA), or 10% HES 200,000/0.5, or Ringer's solution to a hematocrit of 15%. Hemodynamics, oxygen transport parameters, pancreatic microcirculation and tissue oxygen tension were evaluated over 6 h. Then the abdomen was closed, animals were extubated and observed for 6 days. After that, the surviving animals were sacrificed and specimens were taken from the pancreas. The histopathologic findings were scored by two blinded pathologists who quantified acinar necrosis, fat necrosis, inflammation and edema. RESULTS: Isovolemic hemodilution with HES plus HBOC-301 reduced mortality and preserved pancreatic microcirculation compared with Ringer's solution, but was not significantly different from hemodilution with HES alone. Only treatment with HES plus HBOC-301 normalized pancreatic tissue oxygen tension compared with IHD with HES or Ringer's solution alone. CONCLUSIONS: IHD with HES plus HBOC-301 as a combination of rheologic and O(2)-delivering therapy may represent a novel therapeutic option for treatment of AP.

Acute Disease↗

Effects of lazaroid U-74389G on acute necrotizing pancreatitis in rats.

The aim of this study was to investigate the influence of U-74389G on acute necrotizing pancreatitis (ANP) induced by glycodeoxycholic acid in rats. The induction of ANP resulted in a significant increase in mortality rate, pancreatic necrosis, and serum levels of amylase, alanine aminotransferase, interleukin-6, tumor necrosis factor alpha, and urea, in lactate dehydrogenase levels in bronchoalveolar lavage fluid, and in the activities of myeloperoxidase and malondialdehyde in pancreas and lung tissue; a significant decrease was observed in serum calcium levels, blood pressure, urine output, and pO(2). The use of U-74389G inhibited the changes in serum urea, pO(2), and tissue levels of myeloperoxidase and malondialdehyde in pancreas and lungs. Moreover, it indicated a limited effect on the course of ANP in the rats and did not reduce mortality and pancreatic damage. Therefore, it may be used in the treatment of lung injury during acute pancreatitis.

Animals↗

MMP-9 in serum correlates with the development of pulmonary complications in experimental acute pancreatitis.

INTRODUCTION: The prediction of the course of acute pancreatitis and its arising complications is of clinical importance. The aim of this study was to judge the time course and relevance of matrix metalloproteinase-9 (MMP-9), a PMN-derived protease, for the development of pulmonary complications in two models of acute pancreatitis. METHODS: MMP-9 was evaluated in a standardized experimental model of acute pancreatitis. Mild edematous (n = 12) and severe necrotizing pancreatitis (n = 48) were induced by intravenous cerulein or intravenous cerulein and intraductal application of glycodeoxycholic acid and compared to control animals. 1, 6, 9, 12, 24 and 72 h after induction, rats were sacrificed and damage to the lung and the pancreas was quantified by histology and extravasation of Evans blue. At 1, 6, 9, 12, 24 and 72 h, we determined MMP-9 in serum by ELISA. RESULTS: In our model, MMP-9 in serum was increased in the group with severe acute pancreatitis in comparison to mild edematous pancreatitis and controls at each evaluated time point (p < 0.05). The maximum release of MMP-9 preceded the development of pulmonary complications, verified by histology and extravasation of Evans blue. MMP-9 showed a negative predictive value of 96.2% and a positive predictive value of 100% for the development of pulmonary complications. CONCLUSION: MMP-9 in serum allows a valid grouping to severe and mild courses of experimental acute pancreatitis with a good predictive value for the development of pulmonary complications. MMP-9 should be evaluated as a valid single marker for the prediction of progression and the development of pulmonary complications in acute pancreatitis in clinical studies.

Animals↗

The low-pressure duct perfusion model of acute pancreatitis.

The low-pressure duct perfusion model reliably produces acute pancreatitis in cats. The main pancreatic duct is made permeable in one of several ways: the perfusion of glycodeoxycholic acid along the main pancreatic duct, the administration of intragastric ethanol, the stimulation of pancreatic secretion into an obstructed duct, or the creation of acute hypercalcemia. Active pancreatic enzymes are then perfused through the main pancreatic duct via a catheter inserted into the duct in the tail of the gland, and acute edematous pancreatitis results. Simultaneous infusion of 16,16-dimethylprostaglandin E2 converts acute edematous into acute hemorrhagic pancreatitis. Histologically, the characteristic changes of human acute pancreatitis are manifest 24 h later: necrosis, polymorphonuclear leukocyte infiltrate, hemorrhage and edema.

Acute Disease↗

The effect of protein-calorie malnutrition on the developing liver.

The effects of protein-calorie malnutrition on bile salt metabolism and liver function were studied. Malnutrition was induced in rabbits by combining litters at 7 days of age (13-16 animals) and results compared to control litters (six-eight animals). At age 29-30 days biliary output from the common bile duct was measured directly for three 1-h periods: under basal conditions, and in response to intravenous infusion of exogenous glycodeoxycholic acid at 0.75 and 1.5 mumol/min/kg, respectively. The bile salt pool size was measured by isotope dilution. Final mean body weight and liver weight were significantly decreased in malnourished animals compared to controls. Liver weight/body weight was also less in the malnourished group. Total liver DNA and protein content, as well as the protein to DNA ratio, were less in the malnourished animals compared to controls. Bile flow and bile salt secretion were reduced in the malnourished group when calculated per kg body weight or per mg liver DNA. Bile salt-dependent flow did not differ significantly, but bile salt-independent flow was significantly less in malnourished animals. Bile salt pool size was decreased in the malnourished group. These findings indicate that malnutrition has a greater impact on liver weight than on total body weight in the preweaning period. In addition, malnutrition reduces bile flow, bile salt secretion, and bile salt pool size which, along with the decrease in bile salt-independent flow, may reflect either an impairment of hepatic uptake function or a delay in postnatal development.

Animals↗

Lexipafant fails to improve survival in severe necrotizing pancreatitis in rats.

CONCLUSION: Lexipafant administration fails to improve survival or lessen the disease severity in two experimental models of severe acute pancreatitis. BACKGROUND: The potent platelet activating factor antagonist Lexipafant has been shown to attenuate the biochemical and histologic changes associated with some animal models of acute pancreatitis, suggesting an important role for this cytokine in its pathogenesis. However, a survival advantage following Lexipafant administration has not been demonstrated. This study evaluates the effect of this platelet activating antagonist on survival in rat models of necrotizing and fulminant hemorrhagic pancreatitis. METHODS: Sprague-Dawley rats underwent induction of either acute necrotizing (n = 40) or hemorrhagic pancreatitis (n = 36) with a time- and pressure-controlled bile duct infusion of 10 mM glycodeoxycholic acid (GDOC) or enterokinase 15 U/mL, in combination with supramaximal cerulein stimulation (5 micrograms/kg/h). Immediately after pancreatitis induction, rats were randomly divided into three groups and received Lexipafant (1 mg or 10 mg) or saline as a continuous intravenous infusion over 9 h. Twenty-four-hour survival rates were determined and severity of pancreatitis was assessed by pancreatic histology scores. RESULTS: The survival rates for GDOC treated rats were 55% (saline), 50% (1 mg Lexipafant) and 50% (10 mg Lexipafant). As expected, all rats induced with enterokinase and treated with saline died with hemorrhagic pancreatitis within 24 h. The same was true of those treated with high- and low-dose Lexipafant, and there was no difference in survival time. Histology scores did not differ between Lexipafant-treated and control rats in either GDOC or enterokinase rats.

Animals↗

Colorimetric determination of glycine conjugates of bile acids.

A simple assay was developed for the determination of glycine-conjugated bile acids. Samples containing the glycine-conjugated bile acids in the range from 15 to 250 nmol were acidified with HCl, and extracted with ethyl acetate containing ethanol (50 ml/l). An aliquot of the organic phase was evaporated to dryness, and the dried residue was treated to develop the color by the addition of acetic anhydride, pyridine and a trace amount of phosphoric acid. the absorbance was measured at 429 or 456 nm after the reaction at 50 degrees C for 2 h. Color development did not occur with unconjugated and taurine-conjugated bile acid. Beer's law was obeyed from 12.5 to 200 nmol in a cuvette. The recovery of the conjugates from the rabbit gall bladder bile and liver homogenate was satisfactory. This method requires no hydrolysis step and is applicable to the determination of glycine-conjugated bile acids in bile, duodenal aspirate and liver homogenate.

Animals↗

Effect of tamoxifen and raloxifene on the conjugation of bile acids with taurine and glycine in ovariectomized rats.

The selective estrogen receptor modulators tamoxifen and raloxifene represent a major therapeutic advance for clinical practice. Unlike estrogens, which are uniformly agonists, tamoxifen and raloxifene exert selective agonistic or antagonistic effects on various estrogen target tissues. The aim of the study was to evaluate the influence of tamoxifen and raloxifene on the conversion of cholesterol to bile acids in estrogen deficiency in rats. The study included 40 female Wistar rats. The animals were divided into four groups: sham operated control, ovariectomized control, ovariectomized rats treated with tamoxifen ovariectomized rats treated with raloxifene. After 42 days of drug administration, bile was collected under anesthesia after administration of radioactive 4-(14)C cholesterol. Bile was assayed for concentration of (14)C bile acids conjugated with taurine and glycine after thin-layer chromatography separation by the use of isotopic technique. In rats treated with tamoxifen and raloxifene, the statistically significant increase in concentration of bile acids conjugated with glycine was observed as compared to ovariectomized animals from control group. Moreover, in rats treated with tamoxifen the concentration of bile acids conjugated with taurine significantly increased. The results of the present study suggest that tamoxifen and raloxifene increase the concentrations of conjugated bile acids in bile.

Animals↗