Deoxycholic acid and the pathogenesis of gall stones

Early diagnosis of the Need for surgical drainage in chronic pancreatitis patients based on serum metabolomics

PURPOSE

Chronic pancreatitis (CP) is a chronic inflammatory disease caused by multiple factors. Numerous studies have found that implementing surgical drainage in the early stages of CP can help alleviate pain and improve prognosis in patients. However, there is currently no consensus on clinical indications for surgical drainage in the early stages of CP, making it difficult to determine whether surgical drainage is necessary. This study aims to use metabolomics methods to identify potential biomarkers that can differentiate whether CP patients require surgical drainage.

METHODS

This study included two cohorts. The training cohort consisted of 32 serum samples from CP patients and 31 serum samples from healthy controls. The validation cohort comprised 73 serum samples from CP patients and 27 serum samples from healthy controls. All serum samples from CP patients were collected within 24 h of hospital admission. Liquid chromatography-tandem mass spectrometry (LC-MS) was used to perform metabolomic analysis on all collected serum samples.

RESULTS

Based on the validation cohort, 24 differential metabolites, including 1-(6-[3]-ladderane-hexanyl)-2-(8-[3]-ladderane-octanyl)-sn-glycerophosphocholine, PE(18:1(9Z)/20:4(5Z,8Z,11Z,14Z)), and PGP(16:0/20:4(5Z,8Z,11Z,14Z)), were identified as potential biomarkers for distinguishing whether CP patients require surgical drainage. Among these, the combination of 1-(6-[3]-ladderane-hexanyl)-2-(8-[3]-ladderane-octanyl)-sn-glycerophosphocholine and PE(18:1(9Z)/20:4(5Z,8Z,11Z,14Z)) demonstrated improved diagnostic value in joint ROC analysis, with an AUC value of 0.819 (95% CI: 0.691-0.924).

CONCLUSION

This study represents the first prospective cohort research to identify 24 differential metabolites in serum through metabolomic profiling, which can be used for the early diagnosis of whether CP patients require surgical drainage.

Microbial metabolite deoxycholic acid-mediated ferroptosis exacerbates high-fat diet-induced colonic inflammation

High-fat diet (HFD) has long been recognized as risk factors for the development and progression of ulcerative colitis (UC), but the exact mechanism remained elusive. Here, HFD increased intestinal deoxycholic acid (DCA) levels, and DCA further exacerbated colonic inflammation. Transcriptome analysis revealed that DCA triggered ferroptosis pathway in colitis mice. Mechanistically, DCA upregulated hypoxia-inducible factor-2α (HIF-2α) and divalent metal transporter-1 (DMT1) expression, causing the ferrous ions accumulation and ferroptosis in intestinal epithelial cells, which was reversed by ferroptosis inhibitor ferrostatin-1. DCA failed to promote colitis and ferroptosis in intestine-specific HIF-2α-null mice. Notably, byak-angelicin inhibited DCA-induced pro-inflammatory and pro-ferroptotic effects through blocking the up-regulation of HIF-2α by DCA. Moreover, fat intake was positively correlated with disease activity in UC patients consuming HFD, with ferroptosis being more pronounced. Collectively, our findings demonstrated that HFD exacerbated colonic inflammation by promoting DCA-mediated ferroptosis, providing new insights into diet-related bile acid dysregulation in UC.

Associations of cholecystectomy with the risk of colorectal cancer: a Mendelian randomization study

BACKGROUND

Cholecystectomy is a standard surgery for patients suffering from gallbladder diseases, while the causal effects of cholecystectomy on colorectal cancer (CRC) and other complications are still unknown.

METHODS

We obtained genetic variants associated with cholecystectomy at a genome-wide significant level ( P value <5 × 10 -8 ) as instrumental variables (IVs) and performed Mendelian randomization (MR) to identify the complications of cholecystectomy. Furthermore, the cholelithiasis was also treated as the exposure to compare its causal effects to those of cholecystectomy, and multivariable MR analysis was carried out to judge whether the effect of cholecystectomy was independent of cholelithiasis. The study was reported based on Strengthening the Reporting of Observational Studies in Epidemiology Using Mendelian Randomization guidelines.

RESULTS

The selected IVs explained 1.76% variance of cholecystectomy. Our MR analysis suggested that cholecystectomy cannot elevate the risk of CRC (odds ratio [OR] =1.543, 95% confidence interval [CI]: 0.607-3.924). Also, it was not significant in either colon or rectum cancer. Intriguingly, cholecystectomy might decrease the risk of Crohn's disease (OR = 0.078, 95% CI: 0.016-0.368) and coronary heart disease (OR = 0.352, 95% CI: 0.164-0.756). However, it might increase the risk of irritable bowel syndrome (IBS) (OR = 7.573, 95% CI: 1.096-52.318). Cholelithiasis could increase the risk of CRC in the largest population (OR = 1.041, 95% CI: 1.010-1.073). The multivariable MR analysis suggested that genetic liability to cholelithiasis could increase the risk of CRC in the largest population (OR = 1.061, 95% CI: 1.002-1.125) after adjustment of cholecystectomy.

CONCLUSIONS

The study indicated that cholecystectomy might not increase the risk of CRC, but such a conclusion needs further proving by clinical equivalence. Additionally, it might increase the risk of IBS, which should be paid attention to in clinical practice.

Increased Risk of Gallstone Disease Following Colectomy for Ulcerative Colitis

OBJECTIVES

Biochemical studies suggest that patients who have had a colectomy or restorative proctocolectomy with ileal pouch-anal anastomosis (IPAA) are at an increased risk of developing gallstone disease, but epidemiological studies are lacking. We evaluated the risk of gallstone disease following colectomy and IPAA.

METHODS

Individuals who had a colectomy were identified from a national cohort of patients with ulcerative colitis (UC), and controls without colectomy were sampled from within the same cohort, matching on gender, calendar year, and year of birth. We used Cox regression to examine the effect of colectomy on the hazard rates of gallstone disease and cholecystectomy, adjusting for alcoholism, stroke, chronic obstructive pulmonary disease, cancer, cardiac disease, diabetes mellitus, hypothyroidism, hyperlipidemia, cirrhosis, obesity, renal failure, and transient ischemic attacks. The effect of an IPAA was determined for patients who had colectomy by including the procedure as a time-dependent variable.

RESULTS

We identified 4548 patients and matched these to 44 372 controls without colectomy. During a median follow-up of 11.9 years, 1963 patients were hospitalized for gallstone disease. Patients who had a colectomy were at an increased risk (adjusted hazard ratio (HR)=1.63 (1.39-1.91)), and sensitivity analyses of the risk of undergoing cholecystectomy revealed a similar association (adjusted HR=1.55 (1.22-1.98)). An IPAA did not affect the risk of developing gallstones among patients who had a colectomy (adjusted HR=1.03 (0.77-1.37)).

CONCLUSION

The risk of gallstone disease increases following colectomy for UC.

Bile Acid Metabolism and Signaling in Cholestasis, Inflammation, and Cancer

Bile acids are synthesized from cholesterol in the liver. Some cytochrome P450 (CYP) enzymes play key roles in bile acid synthesis. Bile acids are physiological detergent molecules, so are highly cytotoxic. They undergo enterohepatic circulation and play important roles in generating bile flow and facilitating biliary secretion of endogenous metabolites and xenobiotics and intestinal absorption of dietary fats and lipid-soluble vitamins. Bile acid synthesis, transport, and pool size are therefore tightly regulated under physiological conditions. In cholestasis, impaired bile flow leads to accumulation of bile acids in the liver, causing hepatocyte and biliary injury and inflammation. Chronic cholestasis is associated with fibrosis, cirrhosis, and eventually liver failure. Chronic cholestasis also increases the risk of developing hepatocellular or cholangiocellular carcinomas. Extensive research in the last two decades has shown that bile acids act as signaling molecules that regulate various cellular processes. The bile acid-activated nuclear receptors are ligand-activated transcriptional factors that play critical roles in the regulation of bile acid, drug, and xenobiotic metabolism. In cholestasis, these bile acid-activated receptors regulate a network of genes involved in bile acid synthesis, conjugation, transport, and metabolism to alleviate bile acid-induced inflammation and injury. Additionally, bile acids are known to regulate cell growth and proliferation, and altered bile acid levels in diseased conditions have been implicated in liver injury/regeneration and tumorigenesis. We will cover the mechanisms that regulate bile acid homeostasis and detoxification during cholestasis, and the roles of bile acids in the initiation and regulation of hepatic inflammation, regeneration, and carcinogenesis.

Improved glycemic control with colesevelam treatment in patients with type 2 diabetes is not directly associated with changes in bile acid metabolism

Bile acids (BAs) are essential for fat absorption and appear to modulate glucose and energy metabolism. Colesevelam, a BA sequestrant, improves glycemic control in type 2 diabetes mellitus (T2DM). We aimed to characterize the alterations in BA metabolism associated with T2DM and colesevelam treatment and to establish whether metabolic consequences of T2DM and colesevelam are related to changes in BA metabolism. Male subjects with T2DM (n = 16) and controls (n = 12) were matched for age and body mass index. BA pool sizes and synthesis/input rates were determined before and after 2 and 8 weeks of colesevelam treatment. T2DM subjects had higher cholic acid (CA) synthesis rate, higher deoxycholic acid (DCA) input rate, and enlarged DCA pool size. Colesevelam resulted in a preferential increase in CA synthesis in both groups. CA pool size was increased whereas chenodeoxycholic acid and DCA pool sizes were decreased upon treatment. Fasting and postprandial fibroblast growth factor 19 (FGF19) levels did not differ between controls and diabetics, but were decreased by treatment in both groups. Colesevelam treatment reduced hemoglobin A1C by 0.7% (P < 0.01) in diabetics. Yet, no relationships between BA kinetic parameters and changes in glucose metabolism were found in T2DM or with colesevelam treatment.

CONCLUSION

Our results reveal significant changes in BA metabolism in T2DM, particularly affecting CA and DCA. Colesevelam treatment reduced FGF19 signaling associated with increased BA synthesis, particularly of CA, and resulted in a more hydrophilic BA pool without altering total BA pool size. However, these changes could not be related to the improved glycemic control in T2DM.

Biliary physiology and disease: reflections of a physician-scientist

A review is presented of Gustav Paumgartner's five decades of research and practice in hepatology focusing on biliary physiology and disease. It begins with studies of the excretory function of the liver including hepatic uptake of indocyanine green, bilirubin, and bile acids. The implications of these studies for diagnosis and understanding of liver diseases are pointed out. From there, the path of scientific research leads to investigations of hepatobiliary bile acid transport and the major mechanisms of bile formation. The therapeutic effects of the hydrophilic bile acid, ursodeoxycholic acid, have greatly stimulated these studies. Although ursodeoxycholic acid therapy for dissolution of cholesterol gallstones and some other nonsurgical treatments of gallstones were largely superseded by surgical techniques, ursodeoxycholic acid is currently considered the mainstay of therapy of some chronic cholestatic liver diseases, such as primary biliary cirrhosis. The major mechanisms of action of ursodeoxycholic acid therapy in cholestatic liver diseases are discussed. An attempt is made to illustrate how scientific research can lead to advances in medical practice that help patients.

Somatostatin analogs and gallstones: a retrospective survey on a large series of acromegalic patients

CONTEXT

Development of gallstones (GS) is reported during the use of somatostatin analogs (SA) that are at present the mainstay for the medical treatment of acromegaly.

OBJECTIVE

To review the prevalence and clinical and biochemical correlates of GS in acromegalic patients.

DESIGN AND SETTING

Retrospective survey on hospital records in acromegalic patients followed up in the last 20 yr in tertiary referral centers.

PATIENTS

Four hundred and fifty-nine patients (272 females).

MAIN OUTCOME MEASURES

According to SA use and GS occurrence, patients were divided in 4 groups: 1) treated with SA without GS (SA+GS-), 2) GS developed while on SA (SA+GS+), 3) GS without SA use (SA-GS+), 4) neither GS nor SA (SA-GS-).

RESULTS

Patients were unevenly distributed in the 4 groups: 232, 125, 38, 64, respectively, pointing to a prevalence of GS in acromegaly of 8.3% at diagnosis with an additional 35% developing GS during SA. GS occurred after 3 months-18 yr (median 3 yr) of SA treatment, were diagnosed after symptoms in 17.6%, were associated to steatosis, ultrasound biliary dilation, and biochemical cholestasis, in 25.6%, 12.8%, and 4% of patients, respectively. Ursodehoxicolic acid was administered after GS occurrence, causing their dissolution in 39% of patients after 3-48 months (median 12). Cholecystectomy was performed in 16.8%of patients in group 2. At multivariate analysis obesity, dyslipidemia, and SA treatment were independent predictors of GS onset, whereas gender and age were not.

CONCLUSIONS

GS are a frequent occurrence in acromegalic patients treated with SA, may occur at any time, but are seldom symptomatic or prompt acute surgery. Obesity and dyslipidemia appear to play a major role in the occurrence of GS in acromegalic patients on SA treatment.

Ursodeoxycholic acid improves gastrointestinal motility defects in gallstone patients

AIM: To simultaneously evaluate the presence of defects in gallbladder and gastric emptying, as well as in intestinal transit in gallstone patients (GS) and the effect of chronic ursodeoxycholic acid (UDCA) administration on these parameters and on serum bile acids and clinical outcome in GS and controls (CTR).

METHODS: After a standard liquid test meal, gallbla-dder and gastric emptying (by ultrasound), oroileal transit time (OITT) (by an immunoenzymatic technique) and serum bile acids (by HPLC) were evaluated before and after 3 mo of UDCA (12 mg/kg bw/d) or placebo administration in 10 symptomatic GS and 10 matched healthy CTR.

RESULTS: OITT was longer in GS than in CTR (P < 0.0001); UDCA significantly reduced OITT in GS (P < 0.0001), but not in CTR. GS had longer gastric half-emptying time (t_1/2) than CTR (P < 0.0044) at baseline; after UDCA, t_1/2 significantly decreased (P < 0.006) in GS but not in CTR. Placebo administration had no effect on gastric emptying and intestinal transit in both GS and CTR.

CONCLUSION: The gallstone patient has simultaneous multiple impairments of gallbladder and gastric emptying, as well as of intestinal transit. UDCA administration restores these defects in GS, without any effect in CTR. These results confirm the pathogenetic role of gastrointestinal motility in gallstone disease and suggest an additional mechanism of action for UDCA in reducing bile cholesterol supersaturation.

Effects of long-term ingestion of difructose anhydride III (DFA III) on intestinal bacteria and bile acid metabolism in humans

Changes in the intestinal microbiota of 10 human subjects with long-term ingestion of 3 g/d difructose anhydride III (DFA III; 4 persons, 2 months; 3 persons, 6 months; and 3 persons, 12 months) were examined by denaturing gradient gel electrophoresis (DGGE). According to the answers to questionnaires, the subjects were divided into two groups (constipated and normal). The DGGE profile was different for every individual and each subject had unique profiles of intestinal microbiota. In the DGGE profiles of constipated subjects, the intensities of bands related to Bacteroides spp. increased. Moreover, the DFA III-assimilating bacteria, Ruminococcus sp. were isolated from subjects who ingested DFA III for 12 months. These strains showed 95% similarity of their 16S rDNA sequences with that of Ruminococcus obeum ATCC 29174(T) (X85101) and produced large amounts of acetic acid. DFA III ingestion for 2 months tended to increase total organic acids in feces, and tended to decrease fecal pH and the secondary bile acid (SBA) ratio in total bile acids. The SBA ratio in total bile acids corresponded to fecal pH. The production of SBA was decreased by low pH in vitro. These results indicated that DFA III ingestion in humans tended to lower intestinal pH, inhibited bile acid 7alpha-dehydroxylation activities and also tended to decrease the SBA ratios in total bile acids. Moreover, as another cause for the decrease in the SBA ratio in total bile acids, it was suggested that the number of bile acid 7alpha-dehydroxylating bacteria were decreased by DFA III ingestion.

Bile salt biotransformations by human intestinal bacteria

Secondary bile acids, produced solely by intestinal bacteria, can accumulate to high levels in the enterohepatic circulation of some individuals and may contribute to the pathogenesis of colon cancer, gallstones, and other gastrointestinal (GI) diseases. Bile salt hydrolysis and hydroxy group dehydrogenation reactions are carried out by a broad spectrum of intestinal anaerobic bacteria, whereas bile acid 7-dehydroxylation appears restricted to a limited number of intestinal anaerobes representing a small fraction of the total colonic flora. Microbial enzymes modifying bile salts differ between species with respect to pH optima, enzyme kinetics, substrate specificity, cellular location, and possibly physiological function. Crystallization, site-directed mutagenesis, and comparisons of protein secondary structure have provided insight into the mechanisms of several bile acid-biotransforming enzymatic reactions. Molecular cloning of genes encoding bile salt-modifying enzymes has facilitated the understanding of the genetic organization of these pathways and is a means of developing probes for the detection of bile salt-modifying bacteria. The potential exists for altering the bile acid pool by targeting key enzymes in the 7alpha/beta-dehydroxylation pathway through the development of pharmaceuticals or sequestering bile acids biologically in probiotic bacteria, which may result in their effective removal from the host after excretion.

Octreotide induced prolongation of colonic transit increases faecal anaerobic bacteria, bile acid metabolising enzymes, and serum deoxycholic acid in patients with acromegaly

BACKGROUND

Acromegalic patients have slow colonic transit, increased rates of deoxycholic acid formation, and an increased prevalence of cholesterol gall stones, especially during long term octreotide treatment. However, the effects of this prolonged large bowel transit time on the numbers of faecal anaerobes and the activities of the enzyme systems which biotransform conjugated cholic acid into unconjugated deoxycholic acid (cholylglycine hydrolase and 7alpha-dehydroxylase) are unknown.

METHODS

Therefore, in 10 non-acromegalic controls, 11 acromegalic patients not treated with octreotide, and 11 acromegalics on long term (8-48 months) octreotide (100-200 mug three times daily subcutaneously), we measured large bowel transit time and, in freshly voided faeces, the activities of the two bile acid metabolising enzymes, and related the results to the proportion of deoxycholic acid in fasting serum. Moreover, in patients with acromegaly, we measured quantitative bacteriology in faeces.

RESULTS

Mean large bowel transit time in acromegalics not treated with octreotide (35 (SEM 6.5) hours) was 66% longer than that in non-acromegalic controls (21 (3.1) hours; NS) and became further prolonged during octreotide treatment (48 (6.6) hours; p<0.001). These octreotide induced changes in transit were associated, in acromegalic patients, with more total (15.0 (2.5) v 6.3 (1.3)x10(9) colony forming units (cfu)/g; p<0.05) and Gram positive (6.3 (2.3) v 3.2 (1.0)x10(9) cfu/g; p<0.05) faecal anaerobes. Mean faecal cholylglycine hydrolase activity in the long term octreotide group (22.0 (6.0)x10(-2) U/mg protein) was 138% greater than that in non-acromegalic controls (12.0 (6.0)x10(-2); p<0.01). Similarly, mean 7alpha-dehydroxylase activity in octreotide treated acromegalics (11.1 (1.18)x10(-4) U/mg protein) was 78% greater than that in patients not receiving long term octreotide (6.3 (0.5)x10(-4); p<0.001). The mean proportion of deoxycholic acid in fasting serum also increased from 18.0 (2.88)% in the untreated group to 29.6 (2.3)% during long term octreotide (p<0.05). There were significant linear relationships between large bowel transit time and: (i) faecal 7alpha-dehydroxylase activity; and (ii) the proportion of deoxycholic acid in fasting serum and between 7alpha-dehydroxylase activity and the proportion of deoxycholic acid in serum.Summary/interpretation: These data suggest that increased deoxycholic acid formation seen in acromegalics during octreotide treatment is due not only to the greater numbers of faecal anaerobes but also to increased activity of the rate limiting enzyme pathway (7alpha-dehydroxylation) converting cholic acid to deoxycholic acid.

Cholelithiatic human gallbladders in vitro fail to respond to cholecystokinin but are responsive to carbachol, histamine, or electrical stimulation

The present investigation was undertaken to delineate the in vitro responsiveness of cholelithiatic gallbladders to cholecystokinin (CCK) and compared with those evoked by carbachol, histamine, or electrical stimulation. Gallbladder muscular strips (2-3 mm wide and 15-20 mm long) from patients undergoing cholecystectomy were used for recording the in vitro contractions evoked by electrical and chemical (carbachol, histamine, or cholecystokinin) stimulation. Stimulation of strips with trains of pulses (5-msec duration, 70 V at 100 Hz) of varying train durations (0.01 to 9 sec) elicited duration-dependent increase in the amplitude of contractions and the maximal contractions were seen with 5 sec. Atropine (0.4 microM) significantly attenuated these contractions, leaving about 34% of contractions, which in turn was abolished by xylocaine. Carbachol produced a concentration-dependent (0.004-0.4 microM) increase in force of contraction and the maximal response was seen at 0.4 microM and abolished by atropine (0.4 microM). Histamine also produced contractions and the maximal contractions were about 35% of the maximal carbachol response. Histamine-induced contractions were not abolished by atropine but were abolished by xylocaine. CCK up to 10 microM failed to evoke any contraction, even though the strips were responsive to carbachol. The results indicate that cholelithiatic gallbladders exhibited responses to electrical stimulation through cholinergic and histaminergic plexuses and they were insensitive to CCK.

Phosphatidylcholine-enriched diet prevents gallstone formation in mice susceptible to cholelithiasis

Cholesterol gallstones affect approximately 10-15% of the adult population in North America. Phosphatidylcholine (PC) is considered to be the main cholesterol solubilizer in bile. This study examined the effect of a PC-enriched diet on gallstone incidence in mice susceptible to cholelithiasis. The result obtained showed that the feeding of a lithogenic (LG) diet for 4 weeks or 8 weeks resulted in cholesterol gallstone incidences of 47% and 89%, respectively. These gallstone incidences were either reduced or prevented when the LG diet was enriched with 2% or 6% PC, respectively. The cholesterol saturation index (CSI) was reduced only in mice fed with LG + 6% PC diet as compared with mice fed the LG diet alone. However, in all groups, the CSI was significantly higher than in mice fed Purina chow diet. The biliary anionic polypeptide fraction (APF) was significantly increased in mice fed the LG + 2% PC diet and was reduced in those fed with LG + 6% PC diet. In conclusion, prevention or delay of gallstone formation was not due to a consistent effect on biliary lipid composition, suggesting a direct effect of PC on cholesterol solubilization and/or the effect of an additional nonlipid biliary component such as APF.

Hepatic overexpression of murine Abcb11 increases hepatobiliary lipid secretion and reduces hepatic steatosis

Abcb11 encodes for the liver bile salt export pump, which is rate-limiting for hepatobiliary bile salt secretion. We employed transthyretin-Abcb11 and BAC-Abcb11 transgenes to develop mice overexpressing the bile salt export pump in the liver. The mice manifest increases in bile flow and biliary secretion of bile salts, phosphatidylcholine, and cholesterol. Hepatic gene expression of cholesterol 7alpha-hydroxylase and ileal expression of the apical sodium bile salt transporter are markedly reduced, whereas gene expression of targets of the nuclear bile salt receptor FXR (ileal lipid-binding protein, short heterodimer partner (SHP) is increased. Because these changes in gene expression are associated with an increased overall hydrophobicity of the bile salt pool and a 4-fold increase of the FXR ligand taurodeoxycholate, they reflect bile salt-mediated regulation of FXR and SHP target genes. Despite the increased biliary secretion of bile salts, fecal bile salt excretion is unchanged, suggestive of an enhanced enterohepatic cycling of bile salts. Abcb11 transgenic mice fed a lithogenic (high cholesterol/fat/cholic acid) diet display markedly reduced hepatic steatosis compared with wild-type controls. We conclude that mice overexpressing Abcb11 display an increase in biliary bile salt secretion and taurodeoxycholate content, which is associated with FXR/SHP-mediated changes in hepatic and ileal gene expression. Because these mice are resistant to hepatic lipid accumulation, regulation of Abcb11 may be important for the pathogenesis and treatment of steatohepatitis.

Incidence of gallstones in chronic renal failure patients undergoing hemodialysis: experience of a center in Turkey

OBJECTIVE

In this case-control study, we sought to determine whether the incidence of gallbladder stones (GBS) was increased in chronic renal failure (CRF) patients on a hemodialysis (HD) program. We also evaluated factors, such as lipid profiles and gallbladder motility, that could affect the formation of GBS. In addition, we reviewed other available studies on this subject and compared the factors that might have some influence on the development of GBS.

METHODS

A total of 182 CRF patients (135 male, 47 female, mean age 32.1 yr) undergoing chronic HD and who were referred to our transplantation center in the last 10 yr and 194 healthy controls (137 male, 57 female, mean age 33.3 yr) were included in the study. Abdominal ultrasound was performed on all patients, and ALT, AST, and lipid profiles were determined. In addition, 19 patients with CRF (12 male, 7 female, mean age 33.5 yr) and 22 controls (14 male, 8 female, mean age 33.2 yr) who were age and sex matched were randomly chosen for gallbladder emptying, monitored by ultrasound at 30-min intervals for 2 h after a mixed meal. Fasting volume, minimal residual volume, and ejection fraction of the gallbladder were assessed. For statistical analysis, chi(2), t test, and logistic regression analysis were used.

RESULTS

GBS were detected in seven patients with CRF (3.85%, 5 male, 2 female) and three controls (1.55%, one male, two female) (p > 0.05). The mean follow-up time of CRF patients after diagnosis was 39.3 months (range: 2-168), the mean duration of HD was 21.8 months (range: 1-120). The analysis of seven stones in the CRF group revealed that five were cholesterol-rich stones, and two were mixed (cholesterol and bilirubin) stones. Cholesterol levels were higher in the control group, and triglycerides were higher in the CRF group, but these findings were nonsignificant (p > 0.05). Other biochemical values were not significantly different between the groups. CRF patients with and without GBS were similar in their duration of CRF and HD, age, and other biochemical parameters (p > 0.05). When gallbladder emptying was considered, there was no difference between the two groups in fasting volume, residual volume, and ejection fraction (CRF: 89.7%; controls: 92.3%) of the gallbladders (p > 0.05).

CONCLUSIONS

We detected similar incidences of GBS in CRF patients undergoing HD and healthy controls, and this was comparable to the results of most of the previous studies. Young male CRF patients had a nonsignificantly higher incidence of GBS than control males. Although cholesterol-rich GBS were predominant, we could not find any significant difference between the groups when factors that could affect GBS formation, such as lipid profiles and gallbladder motility, were taken into account.

Alternative treatment of gallbladder disease

Major risk factors for gallbladder disease include a sedentary lifestyle and a diet rich in refined sugars. In genetically prone individuals, these two factors lead to an abnormal bile composition, altered gut microflora, and hyperinsulinemia, with resulting gallstone formation. As a large percentage of gallbladder patients have continued digestive complaints following cholecystectomy, the author examines complementary and alternative medicine (CAM) treatments to counteract gallstone formation. Herbal medicine such as turmeric, oregon grape, bupleurum, and coin grass may reduce gallbladder inflammation and relieve liver congestion. Elimination of offending foods, not necessarily 'fatty' foods, is often successful and recommended by many holistic physicians. Regular aerobic exercise has a beneficial effect on hyperinsulinemia, which is often associated with gallbladder disease. Dietary changes that lower plasma insulin levels, such as a change in dietary fats and substitution of unrefined carbohydrates for refined carbohydrates, may also be helpful.

Cholesterol gallstones

Cholesterol cholelithiasis is common in Western populations and represents a consequence of altered cholesterol homeostasis. Gallstones form because of a complex and incompletely understood series of metabolic and physicochemical events that promote cholesterol crystallization in bile. In the context of current paradigms, this article reviews recent progress in research on biliary lipid metabolism and the pathogenesis of cholesterol gallstones.

Effects of cisapride on gall bladder emptying, intestinal transit, and serum deoxycholate: a prospective, randomised, double blind, placebo controlled trial

BACKGROUND

Octreotide inhibits gall bladder emptying and prolongs intestinal transit. This leads to increases in the proportion of deoxycholic acid in, and cholesterol saturation of, gall bladder bile, factors that contribute to the pathogenesis of octreotide induced gall stones.

AIMS

To see if an intestinal prokinetic, cisapride, could overcome these adverse effects of octreotide and if so, be considered as a candidate prophylactic drug for preventing iatrogenic gall bladder stones.

METHODS

A randomised, double blind, placebo controlled, crossover design was used to examine the effects of cisapride (10 mg four times daily) on gall bladder emptying, mouth to caecum and large bowel transit times, and the proportions of deoxycholic acid and other bile acids, in fasting serum from: (i) control subjects (n=6), (ii) acromegalic patients not treated with octreotide (n=6), (iii) acromegalics on long term octreotide (n=8), and (iv) patients with constipation (n=8).

RESULTS

Cisapride had no prokinetic effect on the gall bladder. In fact, it significantly increased both fasting and postprandial gall bladder volumes. However, it shortened mouth to caecum (from 176 (13) to 113 (11) minutes; p<0.001) and large bowel (from 50 (3.0) to 31 (3.4) h; p<0.001) transit times. It also reduced the proportion of deoxycholic acid in serum from 26 (2.3) to 15 (1.8)% (p<0.001), with a reciprocal increase in the proportion of cholic acid from 40 (3.5) to 51 (3.8)% (p<0.01). There were significant linear relationships between large bowel transit time and the proportions of deoxycholic acid (r=0.81; p<0.001) and cholic acid (r=-0.53; p<0.001) in fasting serum. INTERPRETATION/SUMMARY: Cisapride failed to overcome the adverse effects of octreotide on gall bladder emptying but it countered octreotide induced prolongation of small and large bowel transit. Therefore, if changes in intestinal transit contribute to the development of octreotide induced gall bladder stones, enterokinetics such as cisapride may prevent their formation.

Gallstones

Gallstones are estimated to affect over 20 million people in the United States. Recent studies have clarified the role of various dietary components in gallstone disease. Also, insulin resistance has been demonstrated to be a risk factor for gallstones. Other research has focused on the pathophysiology of gallstones and on clarifying the underlying mechanisms of previously noted risk factors for gallstones. New techniques for the noninvasive diagnosis of bile duct stones continue to be developed and tested. These techniques include computed tomography and magnetic resonance cholangiography. The impact and appropriateness of laparoscopic cholecystectomy continue to debated, and studies point to both overuse and underuse of this operation in the management of the disease.

Influence of pH on the phase distribution of nascent deoxycholic acid in fresh human cecal aspirates

Prolonged large bowel transit time and an associated increase in the proportion of deoxycholic acid (DCA) in serum and bile have been implicated in the development of cholesterol-rich gallstones and colon cancer. Prolongation of intestinal transit also increases intracolonic pH that, we hypothesized, should favor the solubilization and absorption of newly formed DCA within the colon. To test this hypothesis, we performed in vitro studies on homogenized cecal aspirates (obtained at colonoscopy) that were incubated anaerobically with [14C]cholic acid for 16 h after which the pH was adjusted to between 4.0 and 7.0 in 0.5-pH unit steps. The resultant reaction mixtures were centrifuged to separate the supernatant from the precipitate, and the specific activity of [14C]DCA was quantitated in both phases. As the pH in the aspirates was manipulated from 4.0 to 7.0, the proportion of newly formed, labeled DCA increased in the supernatant and fell in the precipitate, particularly at a hydrogen ion concentration of <100 x 10(-7) (equivalent to pH 5.0-7.0). These results show that the solubility of DCA in colonic contents increases with increasing pH. If solubility is rate limiting, this should lead to increased absorption that, in turn, would explain why the proportion of DCA in serum and bile increases with the prolongation of large bowel transit time.

Cisapride improves gallbladder emptying and bile lipid composition in patients with gallstones

BACKGROUND AND AIM

Biliary cholesterol supersaturation, gallbladder stasis and delayed intestinal transit are the key events in cholesterol gallstone formation. We studied the effect of cisapride, a prokinetic drug, on gallbladder emptying and bile composition in patients with gallstone disease undergoing cholecystectomy.

METHODS

Gallbladder emptying, cholesterol saturation index (CSI) and nucleation time were studied in 21 patients with gallstone disease. Eleven patients (cisapride group, age 41.9 +/- 2.9 years) received tablet cisapride 10 mg t.i.d. for 2 weeks, while 10 patients (placebo group, age 42.1 +/- 1.9 years) received placebo for the same duration. Gallbladder emptying was repeated in all patients after a 2-week treatment with cisapride or placebo. Gallbladder bile was obtained at the time of surgery for the measurement of CSI and nucleation time.

RESULTS

Residual volume of the gallbladder decreased (mean +/- SE, 18.6 +/- 2.5 mL vs 10.0 +/- 1.1 mL, P = 0.007), and the ejection fraction increased (43.5 +/- 5.3% vs 60.0 +/- 3.2%, P = 0.007) in patients in the cisapride group, while no change was observed in placebo group patients. Nucleation time was higher in the cisapride group than in the placebo group (14.9 +/- 1.3 days vs 8.0 +/- 0.9 days, P = 0.003). Patients in the cisapride group had a significantly lower cholesterol concentration (molar percentage, 5.1 +/- 0.3% vs 6.8 +/- 0.8%, P = 0.049) and CSI (1.0 +/- 0.1 vs 1.36 +/- 0.11, P = 0.034) than patients in the placebo group.

CONCLUSION

Cisapride improves gallbladder emptying and bile lithogenicity in patients with gallstone disease.

Interdigestive gallbladder emptying, antroduodenal motility, and motilin release patterns are altered in cholesterol gallstone patients

The role of interdigestive gallbladder emptying in gallstone formation is unknown. In fasting healthy subjects, gallbladder emptying is associated with antral phase III of the migrating motor complex (MMC) and high plasma motilin. Therefore, gallbladder volumes and motilin levels were measured during 13 MMC cycles in 10 cholesterol gallstone patients and compared with 20 MMC cycles in 10 healthy subjects. MMC cycle length was longer in gallstone patients than in healthy subjects (158.2 +/- 17.0 vs 105.5 +/- 10.4 min, respectively; P < 0.05), due to longer phase I (39.8 +/- 5.7 vs 17.2 +/- 3.7 min, respectively; P < 0.05). In contrast to healthy subjects, gallstone patients had no significant fluctuations of gallbladder volume during the MMC cycle, and motilin concentrations were not different in MMC cycles with phase III originating in antrum or duodenum. During MMC cycles with phase III originating in the duodenum, motilin levels were twice as high in gallstone patients as in healthy subjects (P < 0.002). In conclusion, cholesterol gallstone patients have an abnormal MMC and motilin release pattern. Their interdigestive gallbladder emptying is reduced and dissociated from the MMC. These disturbances may contribute to gallstone formation.

Biliary lipid composition in cholesterol microlithiasis

BACKGROUND

Little information is available on the pathogenesis of cholesterol microlithiasis, and it is not clear if biliary lipid composition in these patients is similar to changes seen in cholesterol gall stone patients.

AIMS

To measure biliary lipid composition in patients with cholesterol microlithiasis.

PATIENTS

Eleven patients with cholesterol microlithiasis, 20 cholesterol gall stone patients, and 17 healthy controls.

METHODS

Duodenal bile was collected in the fasting state during ceruletide infusion. Biliary cholesterol, phospholipids, and total bile acids were analysed by enzymatic assays, and conjugated bile acids by high pressure liquid chromatography.

RESULTS

Patients with microlithiasis had a cholesterol saturation index significantly higher than controls (mean value 1.30 (95% confidence interval 1.05-1.54) v 0.90 (0.72-1.08)) but similar to gall stone patients (1.51 (1.40-1.63)). This was due to a significant decrease in per cent phospholipid (10.0% (7.1-12.8)) compared with controls (21.4% (18.1-24.6)) and gall stone patients (24.9% (20.5-29.3)). Per cent cholesterol was similar in patients with microlithiasis and controls (5.3% (4.5-6.1) and 5.6 % (4.3-6.8), respectively) but was significantly increased in gall stone patients (10.9% (9.3-12.4)). Bile acid composition in patients with microlithiasis was similar to controls whereas in gall stone patients deoxycholic acid was significantly increased: 27.3% (24.8-29.7) v 19.0% (15.7-22.2) in controls and 20.6% (14.9-26.2) in patients with microlithiasis.

CONCLUSION

Patients with cholesterol microlithiasis have biliary cholesterol supersaturation, similarly to cholesterol gall stone patients. Whereas in the latter this is due to increased per cent cholesterol, in patients with microlithiasis this is caused by phospholipid deficiency, with normal per cent cholesterol and normal biliary bile acid composition.

Association of bowel movement frequency and use of laxatives with the occurrence of symptomatic gallstone disease in a prospective study of women

OBJECTIVES

The authors prospectively examined the association between bowel movement frequency (used as a proxy for intestinal transit), laxative use, and the risk of symptomatic gallstone disease.

METHODS

A total of 79,829 women, aged 36-61 yr, without a history of symptomatic gallstone disease and free of cancer, responded to a mailed questionnaire in 1982 that assessed bowel movement frequency and use of laxatives. Between 1984 and 1996, 4,443 incident cases of symptomatic gallstone disease were documented. Relative risks (RRs) of symptomatic gallstone disease and 95% confidence intervals (CIs) were calculated using logistic regression.

RESULTS

After controlling for age and established risk factors, the multivariate RRs were, compared to women with daily bowel movements, 0.97 (95% CI 0.86-1.08) for women with bowel movements every third day or less, and 1.00 (95% CI 0.91-11.1) for women with bowel movement more than once daily. No trend was evident. As compared to women who never used laxatives in 1982, a significant modest inverse association was seen for monthly laxative use, with a multivariate RR of 0.84 (95% CI 0.72-0.98), and weekly to daily laxative use was associated with a RR of 0.88 (95% CI 0.78-1.02).

CONCLUSIONS

These findings do not support an association between infrequent bowel movements and risk of symptomatic gallstone disease in women, and indicate that simple questions directed at bowel movement frequency are unlikely to enhance our ability to predict risk of symptomatic gallstone disease. The slightly inverse association between use of laxatives and risk of symptomatic gallstone disease may be due to a mechanism that is not related to bowel movement frequency.

Gallstones and cholecystectomy in modern Britain

BACKGROUND

It has been suggested that gallstone disease is now commoner, and that this might explain an increase in cholecystectomy rates, though conclusive evidence has been lacking.

METHODS

All the non-forensic necropsy results for Dundee 1953-98 were examined to assess the prevalence of gallstone disease. The NHS Scotland annual cholecystectomy figures were extracted from their earliest availability in 1961 up to the present. The subgroup of patients from Dundee was analysed separately, as were laparoscopic procedures, which were recorded from 1991.

RESULTS

Gallstone disease was much commoner in 1974-98 than in 1953-73. Increasing age was the main determinant of gallstone disease. Though gallstone disease was commoner in women than men aged 40-89, there was no sex difference under 40 or over 90 years. Cholecystectomy became much commoner in the 1960s when frequency of gallstone disease did not change. It increased further in the 1970s, peaking in 1977-8. There was a gradual fall in rates in the 1980s when gallstone prevalence remained high. There was a further moderate rise in the 1990s after the wide introduction of laparoscopic cholecystectomy. Cholecystectomy is now much commoner in young women and this change started in the 1960s. By contrast, cholecystectomy in men has become more prevalent in the older age group.

CONCLUSIONS

Gallstones were definitely more common in both sexes at all ages over 40 in the last 25 years. Changes in the cholecystectomy rates are only partly explained by changes in gallstone prevalence, and are more determined by surgical practice.

Mechanism for the transit-induced increase in colonic deoxycholic acid formation in cholesterol cholelithiasis

BACKGROUND & AIMS

Many patients with cholesterol gallbladder stones (GBS) have a high percentage of deoxycholic acid (DCA) in gallbladder bile (all of which are in the conjugated form), probably as a result of prolonged large bowel transit times (LBTT). However, whether the prolonged LBTT increases DCA formation, solubilization, or absorption (or all 3) is not known.

METHODS

In 40 subjects (20 with GBS; age range, 24-74 years), we measured LBTT using radiopaque markers, and intestinal luminal pH by radiotelemetry. We also measured quantitative anaerobic bacteriology and the activities of 2 bile acid-metabolizing enzymes in fresh cecal aspirates obtained during clinically indicated unprepared colonoscopy, and related these results to the percentage of DCA in fasting serum measured by gas chromatography-mass spectrometry.

RESULTS

Compared with controls, GBS patients had longer LBTT (mean 23.1 +/- SEM 2.8 h vs. 36.5 +/- 3.3 h; P < 0.01); more total (2.7 +/- 0.6 x 10(9) vs. 5.9 +/- 1.5 x 10(9) cfu/mL) and Gram-positive (9.5 +/- 3.1 x 10(8) vs. 18.0 +/- 4.1 x 10(8) cfu/mL; P < 0.05) anaerobes; and greater 7alpha-dehydroxylating (7alpha-DH) activity (3.39 +/- 0.59 vs. 10.37 +/- 1.15 x 10(-4) U/mg protein) in the cecal aspirates. They also had higher intracolonic pH values (P < 0.02) and increased percentages of DCA in fasting serum (13.4% +/- 1.52% vs. 21.8% +/- 2. 19%; P < 0.005). Results of univariate and multivariate analyses confirmed that LBTT was critical in determining the percentage of DCA in serum and showed that 7alpha-DH activity and apparent distal colonic pH were also significant independent variables.

CONCLUSIONS

Slow colonic transit (more time), increased Gram-positive anaerobes (more bacteria), and greater 7alpha-DH activity (more enzyme) favor enhanced DCA formation; transit-induced increases in distal colonic luminal pH favor enhanced DCA solubilization/bioavailability; and increases in LBTT (more time) again favor DCA absorption.

Review article: epidemiology of gall-bladder disease--role of intestinal transit

Recent epidemiological studies have suggested that hyperinsulinaemia may be a central factor in the pathogenesis of cholesterol gallstones, explaining a probable link with physical inactivity as well as abdominal adiposity. There is also increasing evidence for the hypothesis that enrichment of bile with DCA. 'the colonic bile acid', leads to enrichment of bile with cholesterol. Biliary DCA can be raised and lowered by slowing down and speeding up colonic transit, respectively. Slow transit is characteristic of non-obese British women with gallstones and of non-obese peasants in a gallstone-prone mountain community. High biliary DCA predicts recurrence of gallstones and so does laxative usage, a pointer to constipation and therefore to slow transit. In some studies, at least, a high fibre intake is protective against gallstones. Much else besides fibre influences colonic function. Future studies of gallstone aetiology should include measurements of colonic function. Measures that speed up colonic transit should be tested for their ability to prevent gallstone formation in high-risk individuals.

Review: pathogenesis of gallstones

The aim of this article is to review selected aspects of the pathogenesis of cholesterol-rich, gall-bladder stones (GBS)--with emphasis on recent developments in biliary cholesterol saturation, cholesterol microcrystal nucleation, statis within the gall-bladder and, particularly, on the roles of intestinal transit and altered deoxycholic acid (DCA) metabolism, in GBS development. In biliary cholesterol secretion, transport and saturation, recent developments include evidence in humans and animals, that bile lipid secretion is under genetic control. Thus in mice the md-2 gene, and in humans the MDR-3 gene, encodes for a canalicular protein that acts as a 'flippase' transporting phospholipids from the inner to the outer hemi-leaflet of the canalicular membrane. In the absence of this gene, there is virtually no phospholipid or cholesterol secretion into bile. Furthermore, when inbred strains of mice that have 'lith genes' are fed a lithogenic diet, they become susceptible to high rates of GBS formation. The precipitation/nucleation of cholesterol microcrystals from supersaturated bile remains a critical step in gallstone formation. methods of studying this phenomenon have now been refined from the original 'nucleation time' to measurement of cholesterol appearance/detection times, and crystal growth assays. Furthermore, the results of recent studies indicate that, in addition to classical Rhomboid-shape monohydrate crystals, cholesterol can also crystallize, transiently, as needle-, spiral- and tubule-shaped crystals of anhydrous cholesterol. A lengthy list of promoters, and a shorter list of inhibitors, has now been defined. There are many situations where GB stasis in humans is associated with an increased risk of gallstone formation--including iatrogenic stone formation in acromegalic patients treated chronically with octreotide (OT). As well as GB stasis, however, OT-treated patients all have 'bad' bile which is supersaturated with cholesterol, has excess cholesterol in vesicles, rapid microcrystal mulceation times and a two-fold increase in the percentage DCA in bile. This increase in the proportion of DCA seems to be due to OT-induced prolongation of large bowel transit time (LBTT). Thus LBTT is linearly related to (i) the percentage of DCA in serum; (ii) the DCA pool size; and (III) the DCA input or 'synthesis' rate. Furthermore, the intestinal prokinetic, cisapride, counters the adverse effects of OT on intestinal transit, and 'normalizes' the percentage of DCA in serum/bile. Patients with spontaneous gallstone disease also have prolonged LBTTs, more colonic gram-positive anaerobes, increased bile acid metabolizing enzymes and higher intracolonic pH values, than stone-free controls. Together, these changes lead to increased DCA formation, solubilization and absorption, Thus, in addition to the 'lithogenic liver' and 'guilty gall-bladder' one must now add the 'indolent intestine' to the list of culprits in cholesterol gallstone formation.

Identification and characterization of a bile acid 7alpha-dehydroxylation operon in Clostridium sp. strain TO-931, a highly active 7alpha-dehydroxylating strain isolated from human feces

Clostridium sp. strain TO-931 can rapidly convert the primary bile acid cholic acid to a potentially toxic compound, deoxycholic acid. Mixed oligonucleotide probes were used to isolate a gene fragment encoding a putative bile acid transporter from Clostridium sp. strain TO-931. This DNA fragment had 60% nucleotide sequence identity to a known bile acid transporter gene from Eubacterium sp. strain VPI 12708, another bile acid-7alpha-dehydroxylating intestinal bacterium. The DNA (9.15 kb) surrounding the transporter gene was cloned from Clostridium sp. strain TO-931 and sequenced. Within this larger DNA fragment was a 7.9-kb region, containing six successive open reading frames (ORFs), that was encoded by a single 8.1-kb transcript, as determined by Northern blot analysis. The gene arrangement and DNA sequence of the Clostridium sp. strain TO-931 operon are similar to those of a Eubacterium sp. strain VPI 12708 bile acid-inducible operon containing nine ORFs. Several genes in the Eubacterium sp. strain VPI 12708 operon have been shown to encode products required for bile acid 7alpha-dehydroxylation. In Clostridium sp. strain TO-931, genes potentially encoding bile acid-coenzyme A (CoA) ligase, 3alpha-hydroxysteroid dehydrogenase, bile acid 7alpha-dehydratase, bile acid-CoA hydrolase, and a bile acid transporter were similar in size and exhibited amino acid homology to similar gene products from Eubacterium sp. strain VPI 12708 (encoded by baiB, baiA, baiE, baiF, and baiG, respectively). However, no genes similar to Eubacterium sp. strain VPI 12708 biaH or baiI were found in the Clostridium sp. strain TO-931 bai operon, and the two putative Eubacterium sp. strain VPI 12708 genes, baiC and baiD, were arranged in one continuous ORF in Clostridium sp. strain TO-931. Intergene regions showed no significant DNA sequence similarity, but primer extension analysis identified a region 115 bp upstream from the first ORF that exhibited 58% identity to a bai operator/promoter region identified in Eubacterium sp. strain VPI 12708. These results indicate that the gene organization, gene product amino acid sequences, and promoters of the bile acid-inducible operons of Clostridium sp. strain TO-931 and Eubacterium sp. strain VPI 12708 are highly conserved.

Deoxycholic acid treatment in patients with cholesterol gallstones: failure to detect a suppression of cholesterol 7alpha-hydroxylase activity

Hillebrant C-G, Nyberg B, Angelin B, Axelson M, Björkhem I, Rudling M, Einarsson C (Huddinge University Hospital and Karolinska Hospital, Karolinska Institute, Stockholm, Sweden). Deoxycholic acid treatment in patients with cholesterol gallstones: failure to detect a suppression of cholesterol 7alpha-hydroxylase activity. J Intern Med 1999; 246: 399-407.

OBJECTIVES

Based on animal studies, hydrophobic bile acids have been postulated to be particularly strong inhibitors of bile acid synthesis. The present study was undertaken to characterize in humans the effects of one of the most hydrophobic of the common bile acids, deoxycholic acid (DCA), on the transcriptional regulation and activity of the cholesterol 7alpha-hydroxylase, on hepatic cholesterol metabolism and on biliary lipid metabolism and plasma lipids. DESIGN, SUBJECTS AND SETTINGS: Thirteen patients with cholesterol gallstone disease were treated with DCA (750 mg day-1) for 3 weeks prior to cholecystectomy. Blood samples were collected before and during treatment. At operation, a liver biopsy and gallbladder bile were obtained. Twenty-eight untreated gallstone patients undergoing cholecystectomy served as controls. The study was carried out at a university hospital.

RESULTS

Deoxycholic acid comprised 72 +/- 6% (mean +/- SEM) of total biliary bile acids in DCA-treated patients (n = 8), and 21 +/- 2% in the controls (n = 16; P < 0.001). Cholesterol saturation of gallbladder bile averaged 102% in both treated (n = 7) and untreated (n = 16) patients. Cholesterol 7alpha-hydroxylase and HMG CoA reductase activities and mRNA levels were not different between DCA-treated and untreated gallstone patients. The LDL receptor mRNA levels were similar in both groups of patients. Plasma levels of total cholesterol were lowered by 10% upon DCA treatment (P < 0.05).

CONCLUSIONS

Treatment with DCA did not significantly affect mRNA levels and activity of hepatic cholesterol 7alpha-hydroxylase or HMG CoA reductase in patients with cholesterol gallstones. There was no effect on the saturation of gallbladder bile, Thus, the present study could not verify that the hydrophobicity of the bile acid pool is a major factor regulating human hepatic cholesterol 7alpha-hydroxylase activity.

The metabolic consequences of slow colonic transit

Intestinal transit has a substantial influence on the enterohepatic circulation of bile acids and steroid hormones, on colonic pH, and on short chain fatty acid concentrations in the distal colon. Slow transit is likely to favor disease processes that are related to over-efficient enterohepatic recirculation and to lack of short chain fatty acid in the distal colon. These include gallstones, large bowel cancer, and possibly breast cancer. The best-documented influence of slow colonic transit is on bile acid metabolism. Slowing colonic transit increases deoxycholate and raises cholesterol saturation of bile, making gallstone formation more likely. In this review, we also examine the evidence that slow colonic transit may be important in the etiology of large bowel and breast cancer. There is a lack of data pertaining to the relationship between colonic transit and diseases such as colon and breast cancer. Should slow colonic transit prove to be a significant factor in the etiology of such diseases, then the health of the population might benefit from dietary and lifestyle changes that speed up intestinal transit.

Partial replacement of bile salts causes marked changes of cholesterol crystallization in supersaturated model bile systems

Cholesterol crystallization is a key step in gallstone formation and is influenced by numerous factors. Human bile contains various bile salts having different hydrophobicity and micelle-forming capacities, but the importance of lipid composition to bile metastability remains unclear. This study investigated the effect of bile salts on cholesterol crystallization in model bile (MB) systems. Supersaturated MB systems were prepared with an identical composition on a molar basis (taurocholate/phosphatidylcholine/cholesterol, 152 mM:38 mM: 24 mM), except for partial replacement of taurocholate (10, 20, and 30%) with various taurine-conjugated bile salts. Cholesterol crystallization was quantitatively estimated by spectrophotometrically measuring crystal-related turbidity and morphologically scanned by video-enhanced microscopy. After partial replacement of taurocholate with hydrophobic bile salts, cholesterol crystallization increased dose-dependently without changing the size of vesicles or crystal morphology and the rank order of crystallization was deoxycholate>chenodeoxycholate>cholate (control MB). All of the hydrophilic bile salts (ursodeoxycholate, ursocholate and beta-muricholate) inhibited cholesterol precipitation by forming a stable liquid-crystal phase, and there were no significant differences among the hydrophilic bile-salt species. Cholesterol crystallization was markedly altered by partial replacement of bile salts with a different hydrophobicity. Thus minimal changes in bile-salt composition may dramatically alter bile lipid metastability.

Partial replacement of bile salts causes marked changes of cholesterol crystallization in supersaturated model bile systems

Cholesterol crystallization is a key step in gallstone formation and is influenced by numerous factors. Human bile contains various bile salts having different hydrophobicity and micelle-forming capacities, but the importance of lipid composition to bile metastability remains unclear. This study investigated the effect of bile salts on cholesterol crystallization in model bile (MB) systems. Supersaturated MB systems were prepared with an identical composition on a molar basis (taurocholate/phosphatidylcholine/cholesterol, 152 mM:38 mM: 24 mM), except for partial replacement of taurocholate (10, 20, and 30%) with various taurine-conjugated bile salts. Cholesterol crystallization was quantitatively estimated by spectrophotometrically measuring crystal-related turbidity and morphologically scanned by video-enhanced microscopy. After partial replacement of taurocholate with hydrophobic bile salts, cholesterol crystallization increased dose-dependently without changing the size of vesicles or crystal morphology and the rank order of crystallization was deoxycholate>chenodeoxycholate>cholate (control MB). All of the hydrophilic bile salts (ursodeoxycholate, ursocholate and beta-muricholate) inhibited cholesterol precipitation by forming a stable liquid-crystal phase, and there were no significant differences among the hydrophilic bile-salt species. Cholesterol crystallization was markedly altered by partial replacement of bile salts with a different hydrophobicity. Thus minimal changes in bile-salt composition may dramatically alter bile lipid metastability.

Prolonged large bowel transit increases serum deoxycholic acid: a risk factor for octreotide induced gallstones

BACKGROUND

Treatment of acromegaly with octreotide increases the proportion of deoxycholic acid in, and the cholesterol saturation of, bile and induces the formation of gallstones. Prolongation of intestinal transit has been proposed as the mechanism for the increase in the proportion of deoxycholic acid in bile.

AIMS

To study the effects of octreotide on intestinal transit in acromegalic patients during octreotide treatment, and to examine the relation between intestinal transit and bile acid composition in fasting serum.

METHODS

Mouth to caecum and large bowel transit times, and the proportion of deoxycholic acid in fasting serum were measured in non-acromegalic controls, acromegalic patients untreated with octreotide, acromegalics on long term octreotide, and patients with simple constipation. Intestinal transit and the proportion of deoxycholic acid were compared in acromegalic patients before and during octreotide.

RESULTS

Acromegalics untreated with octreotide had longer mouth to caecum and large bowel transit times than controls. Intestinal transit was further prolonged by chronic octreotide treatment. There were significant linear relations between large bowel transit time and the proportion of deoxycholic acid in the total, conjugated, and unconjugated fractions of fasting serum.

CONCLUSIONS

These data support the hypothesis that, by prolonging large bowel transit, octreotide increases the proportion of deoxycholic acid in fasting serum (and, by implication, in bile) and thereby the risk of gallstone formation.

Deoxycholic acid is not related to lithogenic factors in gallbladder bile

The influence of deoxycholic acid (DCA) on the factors in gallbladder bile responsible for cholesterol gallstone disease has been a controversial subject of discussion. This might be partially due to patient selection or inappropriate methods. Therefore, we investigated the relationship between the percentage of DCA and lithogenic factors in the gallbladder bile of patients with cholesterol gallstones and with normal or moderately impaired gallbladder contractility. Patients with pigment stones served as a control group. The percentage of DCA in the gallbladder bile of 20 patients with cholesterol stones (23.2%+/-6.5%; mean+/-SD) was comparable to the DCA percentage in the gallbladder bile of 11 patients with pigment stones (26.5%+/-8.5%). No correlation was seen between the DCA percentage of total bile acids and the crystal observation time, cholesterol saturation index (CSI), total protein value, mucin level, and amount of cholesterol in vesicles or crystals in the total group of patients or in the subgroups with cholesterol or pigment stones, respectively. The lack of correlation between DCA percentage and CSI was determined in native bile (r = 0.048) as well as in crystal-free bile after ultracentrifugation (r = 0.107). Our findings demonstrate that in patients with gallstones, the percentage of DCA in gallbladder bile is not related to any of the known biliary factors associated with cholesterol gallstone disease. We conclude that in patients with normal or moderately impaired gallbladder function, an elevated DCA level in the gallbladder bile is of minor pathophysiologic significance for the formation of cholesterol gallstones.

Physical and metabolic factors in gallstone pathogenesis

Gallstones form when the tenuous balance of solubility of biliary lipids tips in favor of precipitation of cholesterol, unconjugated bilirubin, or bacterial degradation products of biliary lipids. For cholesterol gallstones, metabolic alterations in hepatic cholesterol secretion combine with changes in gallbladder motility and intestinal bacterial degradation of bile salts to destabilize cholesterol carriers in bile and produce cholesterol crystals. For black pigment gallstones, changes in heme metabolism or bilirubin absorption lead to increased bilirubin concentrations and precipitation of calcium bilirubinate. In contrast, mechanical obstruction of the biliary tract is the major factor leading to bacterial degradation and precipitation of biliary lipids in brown pigment stones. Further understanding of the physical and metabolic factors of cholesterol and black pigment formation is likely to provide interventions to interrupt the earliest stages of gallstone formation.

Altered migrating myoelectrical complex in an animal model of cholesterol gallstone disease: the effect of erythromycin

BACKGROUND

The ground squirrel on a high cholesterol diet exhibits prolonged intestinal transit, a pathogenetic factor in cholesterol gallstone formation.

AIMS

To examine the effect of a high cholesterol diet on the characteristics of the migrating myoelectrical complex (MMC) and the potential benefit of erythromycin.

METHODS

Twenty four animals received either a trace (controls) or a 1% (high) cholesterol diet. After four weeks, five bipolar jejunal and terminal ileal electrodes were implanted. Seven days later, myoelectric activity was measured in conscious, fasted animals before and after treatment with erythromycin. Biliary lipid composition was assessed.

RESULTS

Compared with controls, animals fed the high cholesterol diet exhibited a prolonged MMC cycle period (70 (6) versus 83 (3) minutes; p<0.05), whereas MMC migration velocity and the proportions of the MMC represented by phases I, II, and III were unchanged. Oral erythromycin significantly shortened the MMC cycle period in animals on the control and high cholesterol diet by 59% and 54% respectively, and increased the proportion of the cycle period occupied by phase III of the MMC in both dietary groups. Gall bladder bile became saturated with cholesterol and crystals developed in nine of 12 animals on the high cholesterol diet; controls had none.

CONCLUSION

Animals fed a high cholesterol diet had a prolonged MMC cycle period. This, along with diminished gall bladder motility, impairs the enterohepatic cycling of bile salts and reduces their hepatic secretion, contributing to the formation of abnormal bile. Erythromycin initiated more frequent cycling of the MMC. Its therapeutic value in cholesterol gallstone formation warrants further evaluation.

The effects of phospholipid molecular species on cholesterol crystallization in model biles: the influence of phospholipid head groups

BACKGROUND/AIMS

Variations in the molecular species of biliary phospholipids have been shown to exert major effects on cholesterol solubility and carriers in model and human biles. The aim of this study was to explore systematically the effects of various phospholipid head groups on the cholesterol crystallization process in model biles.

METHODS

Three different control model biles were prepared using varying proportions of egg lecithin, cholesterol and Na taurocholate. In the test biles, 20% of the egg lecithin was replaced with synthetic phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol or phosphatidylcholine, keeping the phospholipid acyl chains and other biliary lipids constant in each experiment.

RESULTS

Phosphatidylserine and phosphatidylglycerol significantly prolonged the crystal observation time, from 2 days to 10 and 6 days, respectively (p<0.02), while phosphatidylethanolamine had little and phosphatidylcholine no effect. The crystal growth rate was significantly slowed down with 20% phospholipid replacement in the following order: phosphatidylglycerol >phosphatidylserine >phosphatidylethanolamine. The total crystal mass after 14 days, as measured by chemical analysis, was reduced by 59% with phosphatidylserine (p<0.05), and by 73% with phosphatidylglycerol (p<0.05); while phosphatidylethanolamine had little effect. The precipitable cholesterol crystal fractions after 14 days were significantly reduced with phosphatidylserine (54%) and phosphatidylglycerol (37%), but not with phosphatidylethanolamine or phosphatidylcholine.

CONCLUSIONS

Variations in the head groups of biliary phospholipids may markedly slow down the cholesterol crystallization process in model biles.

Increased saturation of the fatty acids in the sn-2 position of phospholipids reduces cholesterol crystallization in model biles

Changes in the molecular structure of biliary phospholipids were shown to have major effects on cholesterol solubility, carriers and crystallization in human and model biles. This study investigated systematically the effects of varying saturation of the phosphatidylcholine (PC) sn-2 fatty acid on the cholesterol crystallization process in 3 different model biles. Twenty % of the egg PC (EPC) in these biles were replaced by synthetic PC's with 16:0-18:0, 16:0-18:1, or 16:0-18:2 fatty acyl chains. With 18:0 in the sn-2 position, the crystal observation time (COT) was prolonged from 2 days in the control EPC solution to 14 days (p<0.05). The crystal growth rate (CGR) was reduced from 0.1 OD/day to unmeasurable levels, and the total crystal mass on day 14 decreased by 86%. The introduction of one (18:1), and two (18:2) double bonds in the sn-2 fatty acid rapidly reversed these effects. Ultracentrifugal analysis showed precipitable cholesterol as monohydrate crystals. In the 16:0-18:0 test solution, most of the precipitable cholesterol remained in the supersaturated multilamellar vesicles. Saturation of the biliary PC sn-2 fatty acyl chain prolongs the COT, slows the CGR, reduces the crystal mass, and extends cholesterol solubility in multilamellar vesicles. Desaturation of the sn-2 fatty acid reverses these effects.

Bile acids in serum and bile of patients with cholesterol gallstone

AIM: To analyze serum bile acids and biliary lipids of patients with cholesterol gallstone(CS) and explore the relationship between deoxycholic acid (DCA) and CS disease.

METHODS: Analysis of bile acids in serum was done with gas-chromatography in two groups: CS group (n = 151) and control group (n = 256). Serum bile acids and biliary lipids were also studied in 90 matched samples.

RESULTS: The serum DCA was 0.955 μmol/L ± 0.078 μmol/L in CS group, which was more than that of control group (0.696 μmol/L ± 0.047 μmol/L), P < 0.01. The ratio of DCA/chenodeoxycholic acids (CDCA) was 1.76 ± 0.30 in CS group, about two times that in control group (0.92 ± 0.14). The mole percent of DCA in bile was positively related to cholesterol saturation index (CSI) (P < 0.01) and the mole percent of CDCA in bile negatively to CSI (P = 0.01). There was correlation between the mole percent of DCA, CDCA and cholic acid in bile and in serum.

CONCLUSION: It is suggested that DCA is lithogenic and the increased amount of DCA or the ratio of DCA/CDCA in serum may be one of the features of cholesterol gallstone patients.

Cholylglycine hydrolase and 7alpha-dehydroxylase optimum assay conditions in vitro and caecal enzyme activities ex vivo

Increasing evidence implicates deoxycholic acid (DCA) in the pathogenesis of cholesterol-rich gallbladder stones. However, relatively little is known about the activities of the two intestinal bacterial enzymes (cholylglycine hydrolase and cholic acid 7alpha-dehydroxylase) responsible for the deconjugation and subsequent dehydroxylation of conjugated cholic acid (CA), to form DCA. We, therefore, established optimal reaction conditions for measuring the activities of these two enzymes in vitro, and applied these conditions to the determination of the enzymes in caecal aspirates from six subjects undergoing clinically-indicated colonoscopy. With respect to cholylglycine hydrolase activity: zero order kinetics were found over 20 min at 37 degrees C (pH optimum 4.0), with Km and Vmax values of 1.66 mmol/l and 0.90 mmol CA min(-1) mg prot(-1), respectively. For cholic acid 7alpha-dehydroxylation: zero order kinetics were found over 7.5 min at 37 degrees C, under anaerobic conditions (pH optimum 8.0), with Km and Vmax values of 5.23 x 10(-8) mol/l and 1.88 x 10(-7) mol DCA min(-1) mg prot(-1), respectively. Applying these reaction conditions to the caecal aspirates, endogenous cholylglycine hydrolase activities ranged from 0.49 to 2.43 units (mg protein[-1] min[-1]) and CA 7alpha-dehydroxylase activities from 1.75 to 5.82 x 10(-7) units (mg protein[-1] min[-1]). This study is unique in assaying quantitatively both the deconjugation and dehydroxylation enzyme activities in human caecal samples--an essential first step to further studies of intestinal bacterial enzymes in the pathogenesis of cholesterol gallstone disease.

Assessment of fecal bacteria with bile acid 7 alpha-dehydroxylating activity for the presence of bai-like genes

Eubacterium sp. strain VPI 12708 has several bile acid-inducible (bai) genes which encode enzymes in the bile acid 7 alpha-dehydroxylation (7 alpha DeOH) pathway. Twelve 7 alpha DeOH-positive intestinal bacterial strains were assayed for 7 alpha DeOH activity, and 13 strains were tested for hybridization with bai genes. Cholic acid 7 alpha DeOH activity varied greatly (> 100-fold) among these strains. Southern blot experiments showed that DNA prepared from 7 of 13 strains hybridized with at least one of the bai genes from Eubacterium sp. strain VPI 12708.

Effect of lactulose and fiber-rich diets on bile in relation to gallstone disease: an update

The primum movens in cholesterol gallstone formation is hepatic cholesterol hypersecretion and chronic supersaturation of bile. From this event a cascade of contributing factors can be differentiated: (i) Motility defects with impaired gallbladder contractility and gallbladder stasis, but also with small and large intestinal hypomotility. (ii) Multiple biochemical defects in gallbladder bile with increased biliary proteins, increased deoxycholic acid and rapid crystallization of biliary cholesterol from supersaturated unstable vesicles. There is considerable evidence that slow intestinal and colonic transit can increase the deoxycholic acid pool size and biliary cholesterol saturation. Changes in intestinal transit influence the anaerobic bacterial enzymatic biotransformation of conjugated cholate to more hydrophobic deoxycholate. This leads to biliary cholesterol hypersecretion and gallstone formation. Prokinetic drugs or administration of lactulose or fiber products like bran can change the slow intestinal transit favourably with subsequent reduction in deoxycholic acid formation and cholesterol saturation of bile. Whether these applications are indeed of value in the long-term prevention of gallstone disease, however, is doubtful, since fiber-rich diet in prevention of gallstone recurrence after complete gallstone dissolution was not successful.

A clinical hepatologist's predictions about non-absorbed carbohydrates for the early twenty-first century

To put these predictions into perspective, the primary indication for lactulose therapy in the treatment of HE and SHE is presented and discussed. Six secondary indications for lactulose therapy are also listed and briefly commented upon. A dozen predictions about the status of lactulose are presented and briefly discussed. A. Lactulose will be the treatment of choice for HE.B. TIPS will be the most common cause of HE.C. Lactulose will not be approved in Mexico. D. Lactulose plus anti-diarrheal drugs will be agents for treatment of HE. E. Lactulose will not be the treatment of choice for constipation. F. Lactulose will not be used for Salmonella or Shigella carrier states. G. Lactulose will be routinely administered prophylactically after TIPS. H. Lactulose will be administered prophylactically to cirrhotic patients with portal hypertension. I. Lactulose plus anti-diarrheal drugs will be used for a variety of diverse purposes: (i) Suppression of bacterial growth; (ii) prevention of bacteriuria; (iii) diminution of cholesterol saturation of bile; (iv) adjunct treatment of gallstones with ursodeoxycholic acid; (v) Prevention of colon carcinoma.