Immunohistochemical inflammation in histologically normal gallbladders containing gallstones.

BACKGROUND: The aim of this study was to establish features of inflammation in histologically normal gallbladders with gallstones and compare the expression of inflammatory markers in acutely and chronically inflamed gallbladders. METHODS: Immunohistochemistry was performed on formalin-fixed paraffin-embedded gallbladders for tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-2R, and substance p in three groups: Group I (n = 60) chronic cholecystitis, Group II (n = 57) acute cholecystitis and Group III (n = 45) histologically normal gallbladders with gallstones. Expression was quantified using the H-scoring system. RESULTS: Median, interquartile range expression of mucosal IL-2R in Groups I (2.65, 0.87-7.97) and II (12.30, 6.15-25.55) was significantly increased compared with group III (0.40, 0.10-1.35, p < 0.05). Submucosal IL-2R expression in Groups I (2.0, 1.12-4.95) and II (10.0, 5.95-14.30) was also significantly increased compared with Group III (0.50, 0.15-1.05, p < 0.05). There was no difference in the lymphoid cell IL-6 expression between Groups I (5.95, 1.60-18.15), II (6.10, 1.1-36.15) and III (8.30, 2.60-26.35, p > 0.05). Epithelial IL-6 expression of Group III (8.3, 2.6-26.3) was significantly increased compared with group I (0.5, 0-10.2, p < 0.05) as was epithelial TNF-α expression in Group III (85.0, 70.50-92.0) compared with Groups I (72.50, 45.25.0-85.50, p < 0.05) and II (61.0, 30.0-92.0, p < 0.05). Lymphoid cell Substance P expression in Groups I (1.90, 1.32-2.65) and II (5.62, 2.50-20.8) was significantly increased compared with Group III (1.0,1.0-1.30, p < 0.05). Epithelial cell expression of Substance P in Group III (121.7, 94.6-167.8) was significantly increased compared with Groups I (75.7, 50.6-105.3, p < 0.05) and II (78.9, 43.5-118.5, p < 0.05). CONCLUSION: Histologically normal gallbladders with gallstones exhibited features of inflammation on immunohistochemistry.

Clinical implication of bactibilia in moderate to severe acute cholecystitis undergone cholecystostomy following cholecystectomy.

There is little evidence of clinical outcome in using antibiotics during the perioperative phase of acute cholecystitis with bactibilia. The aim of current study is to examine the effect of bactibilia on patients with acute cholecystitis and their perioperative clinical outcome. We performed a retrospective cohort analysis of 128 patients who underwent cholecystectomy for acute cholecystitis with moderate and severe grade. Patients who were positive for bactibilia were compared to bactibilia-negative group in following categories: morbidity, duration of antimicrobial agent use, in-hospital course, and readmission rate. There was no difference in morbidity when patients with bactibilia (n = 70) were compared to those without (n = 58) after cholecystectomy. The duration of antibiotics use and clinical course were also similar in both groups. In severe grade AC group (n = 18), patients used antibiotics and were hospitalized for a significantly longer period of time than those in the moderate grade AC group. The morbidity including surgical site infection, and readmission rates were not significantly different in moderate and severe grade AC groups. In moderate and severe AC groups, bactibilia itself did not predict more complication and worse clinical course. Antibiotics may be safely discontinued within few days after cholecystectomy irrespective of bactibilia when cholecystectomy is successful.

Neutrophils injure gallbladder interstitial Cajal-like cells in a guinea pig model of acute cholecystitis.

Acute cholecystitis is a common disease with gallbladder dysmotility. Disease pathogenesis involves immune cell infiltration as well as changes in gallbladder interstitial Cajal-like cells (ICLCs). However, it remains unclear if or how the immune cells affect ICLC morphology, density, distribution, and function in gallbladder tissue during acute cholecystitis. In this study, we explored the acute cholecystitis-related alterations in gallbladder ICLCs in a guinea pig model, focusing on the effects of neighboring neutrophils. Adult guinea pigs were randomly divided into four groups (control, 24 hr common bile duct ligation [CBDL], 48-hr CBDL, and antipolymorphonuclear neutrophil [PMN] treated) and analyzed using methylene blue staining and immunofluorescence. Gallbladder contractility was also monitored. To culture gallbladder ICLCs, collagenase digestion was performed on tissue from 10- to 15-day-old guinea pigs. Neutrophils isolated from the peripheral blood of experimental animals 48-hr postsurgery were also cocultured with the gallbladder ICLCs. Intracellular calcium was detected with Fluo-4 AM dye. Our results showed that gallbladder ICLC density significantly declined during acute cholecystitis and was accompanied by shortening of the cellular processes and damage to their network-like structure. However, pretreatment with anti-PMN partially prevented these changes. Gallbladder contraction was also significantly decreased during acute cholecystitis, and this appeared to be mediated by the neutrophils. Moreover, ICLCs cocultured with neutrophils also had shortened and reduced processes and impaired network-like structure formation. Intracellular calcium transient was less sensitive to contraction agonists and inhibitors when cocultured with neutrophils. Taken together, neutrophils greatly affect gallbladder ICLCs and dysmotility during acute cholecystitis.

Differential proteomics analysis of bile between gangrenous cholecystitis and chronic cholecystitis.

To establish human biliary protein expression profiles of gangrenous cholecystitis, chronic cholecystitis, and to discover differently expressed proteins for gangrenous cholecystitis by comparative proteomics, we gathered human gallbladder bile samples from gangrenous cholecystitis and chronic cholecystitis patients, respectively After removing the bile salts and lipid peptide fragments were identified by the iTRAQ-coupled LC-MS/MS technology,then identified in SwissProt with Mascot software. A total of 2251 proteins from chronic cholecystitis patients and 2180 proteins from gangrenous cholecystitis patients were identified. A total of 575 differential proteins were found between gangrenous cholecystitis and chronic cholecystitis, 159 proteins were over-expressed and 416 proteins were under-expressed in gangrenous cholecystitis. By bio-informatics analysis, in gangrenous cholecystitis, cell death, necrosis,immune response of neutrophils, apoptosis and degranulation of cells were activated; while cell survival, fatty acid metabolism, transport of molecular and proliferation of cells were inhibited, which might reflect the de-compensatory phase. Pathway analysis showed acute phase proteins were changed, indicating the role of the inflammatory response in the pathogenesis of gangrenous cholecystitis. Six acute phase proteins were found up-regulated,implying a close linkage to gangrenous gallbladder. Our study could be applicable in the biomarker discovery of gangrenous cholecystitis.

FGFR3 mutation increases bladder tumourigenesis by suppressing acute inflammation.

Recent studies of muscle-invasive bladder cancer show that FGFR3 mutations are generally found in a luminal papillary tumour subtype that is characterised by better survival than other molecular subtypes. To better understand the role of FGFR3 in invasive bladder cancer, we examined the process of tumour development induced by the tobacco carcinogen OH-BBN in genetically engineered models that express mutationally activated FGFR3 S249C or FGFR3 K644E in the urothelium. Both occurrence and progression of OH-BBN-driven tumours were increased in the presence of an S249C mutation compared to wild-type control mice. Interestingly, at an early tumour initiation stage, the acute inflammatory response in OH-BBN-treated bladders was suppressed in the presence of an S249C mutation. However, at later stages of tumour progression, increased inflammation was observed in S249C tumours, long after the carcinogen administration had ceased. Early-phase neutrophil depletion using an anti-Ly6G monoclonal antibody resulted in an increased neutrophil-to-lymphocyte ratio at later stages of pathogenesis, indicative of enhanced tumour pathogenesis, which supports the hypothesis that suppression of acute inflammation could play a causative role. Statistical analyses of correlation showed that while initial bladder phenotypes in morphology and inflammation were FGFR3-dependent, increased levels of inflammation were associated with tumour progression at the later stage. This study provides a novel insight into the tumour-promoting effect of FGFR3 mutations via regulation of inflammation at the pre-tumour stage in the bladder. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Acute Cholecystitis Reduces Interstitial Cells of Cajal in Porcine Gallbladder Through Decreased mRNA Synthesis.

BACKGROUND/AIMS: Acute cholecystitis is a common gastrointestinal disorder, often characterized by acute cholecystitis with gallbladder motility disorder. Interstitial cells of Cajal (ICCs) are the pacemaker cells of gut motility in the gastrointestinal tract. Disruption of ICC function is related to motility disorders. The aim of this study was to explore the cellular and molecular mechanisms of ICCs in acute cholecystitis and after the resolution of acute inflammation. MATERIALS AND METHODS: Fifty adult guinea pigs were randomly divided into five groups: a sham-administered group (control group); two groups that were intraperitoneally administered an anti-polyclonal neutrophil (PMN) antibody 24 h before common bile duct ligation (CBDL); and two groups of guinea pigs that were subjected to CBDL without receiving the PMN antibody. Guinea pigs that underwent CBDL were held for 24 h or 48 h after surgery before being subjected to laparotomy and cholecystectomy. Immunohistochemistry, TUNEL assays, western blotting, and real-time PCR were performed to determine ICC morphology and density, to detect ICC apoptosis, and to examine stem cell factor (SCF) and c-kit protein expression and SCF and c-kit mRNA levels, respectively. RESULTS: Both hematoxylin-eosin staining and histological inflammation scores in the PMN groups were lower than those in the control groups (P < 0.01). No differences were observed in ICC morphology between groups. During acute cholecystitis, ICCs numbers were reduced. Conversely, the density of ICCs increased after inflammation was relieved (P < 0.01). In addition, SCF and c-kit protein and mRNA expression levels decreased during acute cholecystitis (P < 0.05) and increased after inflammation was relieved (P < 0.05). Furthermore, ICC apoptosis increased during acute cholecystitis and decreased after resolution of acute cholecystitis (P < 0.01). CONCLUSIONS: In acute cholecystitis, ICC injury may be related to gallbladder motility disorder.

Cholecystectomy during ceftriaxone therapy. A translational study with a new rabbit model

Abstract Purpose: To evaluate the actual incidence of both microlithiasis and acute cholecystitis during treatment with intravenous ceftriaxone in a new rabbit model. Methods: New Zealand rabbits were treated with intravenous ceftriaxone or saline for 21 days. Ultrasound monitoring of the gallbladder was performed every seven days until the 21st day when histopathology, immunohistochemistry for proliferating cell nuclear antigen (PCNA), pro-caspase-3 and CD68, liver enzyme biochemistry, and chromatography analysis of the bile and sediments were also performed. Results: All animals treated with ceftriaxone developed acute cholecystitis, confirmed by histopathology (P<0.05) and biliary microlithiasis, except one that exhibited sediment precipitation. In the group treated with ceftriaxone there was an increase in pro-caspase-3, gamma-glutamyl transpeptidase concentration, PCNA expression and in the number of cells positive for anti-CD68 (P<0.05). In the ceftriaxone group, the cholesterol and lecithin concentrations increased in the bile and a high concentration of ceftriaxone was found in the microlithiasis. Conclusion: Ceftriaxone administered intravenously at therapeutic doses causes a high predisposition for lithogenic bile formation and the development of acute lithiasic cholecystitis.

Cholecystectomy during ceftriaxone therapy. A translational study with a new rabbit model.

PURPOSE: To evaluate the actual incidence of both microlithiasis and acute cholecystitis during treatment with intravenous ceftriaxone in a new rabbit model. METHODS: New Zealand rabbits were treated with intravenous ceftriaxone or saline for 21 days. Ultrasound monitoring of the gallbladder was performed every seven days until the 21st day when histopathology, immunohistochemistry for proliferating cell nuclear antigen (PCNA), pro-caspase-3 and CD68, liver enzyme biochemistry, and chromatography analysis of the bile and sediments were also performed. RESULTS: All animals treated with ceftriaxone developed acute cholecystitis, confirmed by histopathology (P<0.05) and biliary microlithiasis, except one that exhibited sediment precipitation. In the group treated with ceftriaxone there was an increase in pro-caspase-3, gamma-glutamyl transpeptidase concentration, PCNA expression and in the number of cells positive for anti-CD68 (P<0.05). In the ceftriaxone group, the cholesterol and lecithin concentrations increased in the bile and a high concentration of ceftriaxone was found in the microlithiasis. CONCLUSION: Ceftriaxone administered intravenously at therapeutic doses causes a high predisposition for lithogenic bile formation and the development of acute lithiasic cholecystitis.

Effect of Neutrophils on Gallbladder Interstitial Cajal-Like Cells in Guinea Pig Model of Acute Cholecystitis.

BACKGROUND: Acute cholecystitis is a common condition in gallbladder motility disorder. Interstitial Cajal-like cells (ICLCs) in the gallbladder are known as one of the players in the complex motility mechanisms affecting gallbladder motility. AIM: This study explored morphological symptoms and molecular mechanisms underlying gallbladder ICLC changes induced by acute cholecystitis. MATERIALS AND METHODS: Fifteen adult guinea pigs were randomly divided into 3 groups: sham-operated group (healthy controls) and 2 experimental groups wherein these guinea pigs were subjected to common bile duct ligation to induce acute cholecystitis. Neutrophils were isolated from the peripheral blood of sham-operated animals and from the experimental animals at 24 and 48 h after surgery, and co-cultured with gallbladder ICLCs. The morphology of gallbladder ICLCs was examined by laser confocal immunofluorescence microscopy, TUNEL assay was used to detect apoptosis, and western blot and real-time PCR were performed to detect stem cell factor (SCF) and c-kit protein and mRNA expression, respectively. RESULTS: No morphological differences in the gallbladder ICLCs were observed between single-culture and co-culture with healthy control neutrophil groups. However, the ICLCs in all co-culture groups with acute inflammation were impaired. In the co-culture groups, the rate of ICLC apoptosis was significantly higher than that in the single-culture group. SCF and c-kit protein and mRNA expression levels decreased in all co-culture groups as well. CONCLUSION: We demonstrated that the neutrophils are involved in gallbladder ICLC injury in acute cholecystitis cases and associated with gallbladder motility disorder.

The Role of Interstitial Cells of Cajal in Acute Cholecystitis in Guinea Pig Gallbladder.

BACKGROUND/AIMS: Acute cholecystitis is common in gallbladder motility disorder. Interstitial cells of Cajal (ICCs) in the gallbladder are involved in the regulation of gallbladder motility. The aim of this study was to explore the change of gallbladder ICCs in acute cholecystitis. METHODS: Thirty adult guinea pigs were randomly divided into 3 groups: a sham-operated group (healthy controls) and 2 study groups. The animals in the study group were subjected to bile duct ligation and then to laparotomy and cholecystectomy at 24 and 48 hours after surgery. Immunohistochemistry, immunohistofluorescence, and laser confocal microscopy were performed to observe the shape, size, morphology, and density of gallbladder ICCs. Western blot and real-time PCR were performed to detect stem cell factor and c-kit protein and mRNA expression, respectively. RESULTS: There were no differences in the shape, size, and morphology of the gallbladder ICCs in the control and the two acute cholecystitis groups. Density of gallbladder ICCs, SCF level, and c-kit protein and mRNA expression all decreased in the acute cholecystitis groups. Further, SCF level and c-kit protein and mRNA expression decreased with progress of acute cholecystitis (all P < 0.05). CONCLUSION: Acute cholecystitis can decrease ICCs through repression of SCF and c-kit expression and that ICCs loss play a role in acute cholecystitis.

[DETERMINATION OF A FATTY ACIDS CONTENT IN BILIARY LIPIDS AS A PROGNOSTIC FACTOR FOR THE COMPLICATIONS OCCURRENCE IN PATIENTS AFTER OPERATIONS FOR AN ACUTE CHOLECYSTITIS IN A HIGH OPERATIVE­ANESTHESIOLOGICAL RISK].

Investigation was conducted with objective to establish a prognostic significance of the fatty acids content in biliary lipids for the complications occurrence in patients, operated on for an acute cholecystitis, while presence of high operative­anesthesiological risk. A fatty acids content in biliary lipids was analyzed in 64 patients in presence of moderate (grade ІІ) and severe (grade ІІІ) course of the disease. Coefficients К1 and К2 for prognostication of postoperative purulent­inflammatory complications occurrence were elaborated, their threshold level (К1=0.59, К2=1.8) was established. There was established, that excess of the threshold meaning of К1 and К2 in a bile of patients, suffering an acute cholecystitis while presence of high operative­anesthesiological risk, constitutes a prognostic criterion for the postoperative purulent­inflammatory complications occurrence

Enhanced expression of cystathionine ß-synthase and cystathionine γ-lyase during acute cholecystitis-induced gallbladder inflammation.

BACKGROUND: Hydrogen sulfide (H2S) has recently been shown to play an important role in the digestive system, but the role of endogenous H2S produced locally in the gallbladder is unknown. The aim of this study was to investigate whether gallbladder possesses the enzymatic machinery to synthesize H2S, and whether H2S synthesis is changed in gallbladder inflammation during acute acalculous cholecystitis (AC). METHODS: Adult male guinea pigs underwent either a sham operation or common bile duct ligation (CBDL). One, two, or three days after CBDL, the animals were sacrificed separately. Hematoxylin and eosin-stained slides of gallbladder samples were scored for inflammation. H2S production rate in gallbladder tissue from each group was determined; immunohistochemistry and western blotting were used to determine expression levels of the H2S-producing enzymes cystathionine ß-synthase (CBS) and cystathionine γ-lyase (CSE) in gallbladder. RESULTS: There was a progressive inflammatory response after CBDL. Immunohistochemistry analysis showed that CBS and CSE were expressed in the gallbladder epithelium, muscular layer, and blood vessels and that the expression increased progressively with increasing inflammation following CBDL. The expression of CBS protein as well as the H2S-production rate was significantly increased in the animals that underwent CBDL, compared to those that underwent the sham operation. CONCLUSIONS: Both CBS and CSE are expressed in gallbladder tissues. The expression of these enzymes, as well as H2S synthesis, was up-regulated in the context of inflammation during AC.

Alpha 1-antitrypsin retention in an ectopic liver.

Ectopic livers are infrequently reported in the literature. The reported size for ectopic livers range from a few millimeters up to several centimeters. They are often clinically silent and incidentally discovered during imaging of the hepatobiliary tract, regional surgical procedures or autopsy. They are predestined for benign liver diseases otherwise observed in normal livers like fatty change or develop malignancies such as hepatocellular carcinoma, in a manner analogous to the parent orthotopic liver. The presence of abnormal alpha 1-antitrypsin retention in an ectopic liver has, to our knowledge, not been reported in the literature. Hereby, we present the first reported case featuring alpha 1-antitrypsin retention in an ectopic liver attached to the fundus of the gallbladder and present the clinical, radiological and pathological findings in a caucasian woman undergoing cholecystectomy for acute cholecystitis. Special liver stains showed an alpha 1-antitrypsin retention which was confirmed immunohistochemically. Although ectopic livers are rare and usually an incidental finding, the radiologist and the surgeon should take this into the differential diagnosis of a mass attached to the gall bladder. A secondary disease should be considered by the pathologist in such a specimen and alpha 1-antitrypsin retention should be ruled out by special liver stains. Finally, such a finding should prompt the managing clinician to exclude systemic alpha-1 antitrypsin deficiency in the patient through further appropriate tests.

[Free radical processes in patients with the acute calculous cholecystitis].

The role of the free radical processes (FRP) is shown and objectified in the development of the acute calculous cholecystitis (ACC). It is revealed on the first day of hospitalization already. In catarrhal and phlegmonic ACC free radical processes changes apply mostly to the oxygen part of the oxidation process. The greatest imbalance of the FRP is registered in the gangrenous ACC. It appeared like decrease of the oxygen and activation of the lipid FRP disregulation. On the first day FRP changes refer to the oxygen part of the oxidation process only. Starts with a second day from the disease début changes in the lipid component of the oxidative stress join the disregulation process. It is proved by the decrease of the antiperoxidant activity of plasma and increase of malondialdehyde. Malondialdehyde level and its rate of rise serve as prognostic criteria of the course and outcome of disease. FRP changes correlate with the clinical presentations of disease. They last till the patient's discharge. The high efficiency of the energetic corrector reamberin in a dose of 400-800 ml was shown in patients with ACC.

[Clinical and laboratory evaluation of the efficiency of parenteral nutrition in destructive forms of acute calculous cholecystitis].

A clinical and laboratory studies were undertaken to evaluate the efficiency of perioperative parenteral nutrition in destructive forms of acute calculous cholecystitis. Based on the general and biochemical blood analyses and the time course of changes in humoral immunological parameters, the authors concluded that enteral tube nutrition had a positive impact on the postoperative period. A nasojejunal access reducing the risk of acute pancreatitis, which was used during tube feeding, showed benefits.

Gallbladder inflammation is associated with increase in mucin expression and pigmented stone formation.

Mucin is a high molecular weight glycoprotein that plays an important role in protecting the gallbladder epithelium from the detergent effect of bile. However, it also participates in gallstone formation. There is little information about a possible relationship between gallbladder inflammation and mucin expression or gallbladder stones' characteristics. The aims of this study were to investigate stone characteristics and patterns of mucin expression in the gallbladder epithelium and bile of gallstone patients, in relation to inflammation. Gallbladder bile and tissue samples from 21 patients were obtained at surgery. Mucin content was evaluated by gel filtration on a Sepharose CL-4B column. Dot blot for bile mucin apoproteins and immunohistochemistry staining for gallbladder mucosal mucin apoproteins were performed with antibodies to MUC2, MUC3, MUC5AC, MUC5B and MUC6. Staining intensity score (0-3) was used for assessment of antigen expression and the level of inflammation. Gallstone cholesterol content was determined in 16 patients. MUC 5AC and MUC 5B were demonstrated in 95.4 and 100% of gallbladder bile samples, respectively. Immunohistochemistry staining with antibodies to MUC 2, MUC 3, MUC 5AC, MUC 5B and MUC 6 were positive in 0, 100, 85.7, 100 and 95.4% of the gallbladder mucosal samples, respectively. Pigmented brown stones were associated with a higher level of gallbladder inflammation. Mucin species expressed in gallbladder epithelium are MUC3, MUC5AC, MUC5B and MUC6. MUC5AC and MUC5B are secreted into bile. Inflammation of the gallbladder is accompanied by a higher level of MUC5AC expression and is associated with pigmented brown stones.

Tight junction proteins in gallbladder epithelium: different expression in acute acalculous and calculous cholecystitis.

There is a paucity of information of tight junction (TJ) proteins in gallbladder epithelium, and disturbances in the structure of these proteins may play a role in the pathogenesis of acute acalculous cholecystitis (AAC) and acute calculous cholecystitis (ACC). Using immunohistochemistry, we investigated the expression of TJ proteins claudin-1, -2, -3, and -4, occludin, zonula occludens (ZO-1), and E-cadherin in 9 normal gallbladders, 30 gallbladders with AAC, and 21 gallbladders with ACC. The number of positive epithelial and endothelial cells and the intensity of the immunoreaction were determined. Membrane-bound and cytoplasmic immunoreactivities were separately assessed. We found that TJ proteins were uniformly expressed in normal gallbladder epithelium, with the exception of claudin-2, which was present in less than half of the cells. In AAC, expression of cytoplasmic occludin and claudin-1 were decreased, as compared with normal gallbladder. In ACC, expression of claudin-2 was increased, and expression of claudin-1, -3, and -4, occludin, and ZO-1 were decreased, as compared with normal gallbladder or AAC. We conclude that there are significant differences in expression of TJ proteins in AAC and ACC, supporting the idea that AAC represents a manifestation of systemic inflammatory disease, whereas ACC is a local inflammatory and often infectious disease.

Ursodeoxycholic acid improves muscle contractility and inflammation in symptomatic gallbladders with cholesterol gallstones.

OBJECTIVE: To examine the mechanisms of action of ursodeoxycholic acid (UDCA) on gallbladder (GB) muscle cells in patients with symptomatic cholesterol gallstones (GSs) as it reduces the incidence of acute cholecystitis. DESIGN AND PATIENTS: A double-blind study was performed on 15 patients, 7 randomised to UDCA and 8 to placebo, treated for 4 weeks before cholecystectomy. Muscle contraction induced by cholecystokinin (CCK)-8, acetylcholine (ACh) and potassium chloride (KCl) was determined in enzymatically isolated GB muscle cells, and cholesterol levels were determined in plasma membranes. H(2)O(2), lipid peroxidation, platelet-activating factor (PAF)-like lipids, prostaglandin E(2) (PGE(2)) and catalase activity were determined as biochemical markers of oxidative stress and inflammation in muscle cells. RESULTS: UDCA significantly increased GB muscle cell contraction induced by all concentrations of CCK-8, ACh and KCl, and reduced the plasma membrane cholesterol (mean (SD) 0.32 (0.16) vs 0.72 (0.5) micromol/mg of protein) compared with placebo. In GB muscle cells, UDCA treatment significantly decreased the levels of H(2)O(2) (4.4 (1.9) vs 13.7 (5.3) micromol/mg of protein), lipid peroxidation (malondialdehyde levels 1.3 (0.4) vs 2.52 (0.7) nmol/100 mg of protein), PAF-like lipids (8.9 (4.9) vs 29.6 (7.1) pg/mg of protein) as well as the production of PGE(2) (142 (47) vs 365 (125) pg/mg of protein) and catalase activity (14.5 (9.4) vs 35.8 (12.7) units/mg of protein) when compared with placebo. CONCLUSION: These studies suggest that UDCA treatment improves GB muscle contractility by decreasing the cholesterol content in the plasma membrane of muscle cells, and the biochemical parameters of oxidative stress, thus explaining its possible therapeutic mechanisms in patients with symptoms of cholesterol GSs.