Gallstone dissolution in man using chenodeoxycholic acid

Synthesis of TUDCA from chicken bile: immobilized dual-enzymatic system for producing artificial bear bile substitute

Bear bile, a valuable animal-derived medicinal substance primarily composed of tauroursodeoxycholic acid (TUDCA), is widely distributed in the medicinal market across various countries due to its significant therapeutic potential. Given the extreme cruelty involved in bear bile extraction, researchers are focusing on developing synthetic bear bile powder as a more humane alternative. This review presents an industrially practical and environmentally friendly process for producing an artificial substitute for bear bile powder using inexpensive and readily available chicken bile powder through an immobilized 7α-,7β-HSDH dual-enzymatic syste. Current technology has facilitated the industrial production of TUDCA from Tauodeoxycholic acid (TCDCA) using chicken bile powder. The review begins by examining the chemical composition, structure, and properties of bear bile, followed by an outline of the pharmacological mechanisms and manufacturing methods of TUDCA, covering chemical synthesis and biotransformation methods, and a discussion on their respective advantages and disadvantages. Finally, the process of converting chicken bile powder into bear bile powder using an immobilized 7α-Hydroxysteroid Dehydrogenases(7α-HSDH) with 7β- Hydroxysteroid Dehydrogenases (7β-HSDH) dual-enzyme system is thoroughly explained. The main objective of this review is to propose a comprehensive strategy for the complete synthesis of artificial bear bile from chicken bile within a controlled laboratory setting.

Bile Acids-A Peek Into Their History and Signaling

Bile acids wear many hats, including those of an emulsifier to facilitate nutrient absorption, a cholesterol metabolite, and a signaling molecule in various tissues modulating itching to metabolism and cellular functions. Bile acids are synthesized in the liver but exhibit wide-ranging effects indicating their ability to mediate organ-organ crosstalk. So, how does a steroid metabolite orchestrate such diverse functions? Despite the inherent chemical similarity, the side chain decorations alter the chemistry and biology of the different bile acid species and their preferences to bind downstream receptors distinctly. Identification of new modifications in bile acids is burgeoning, and some of it is associated with the microbiota within the intestine. Here, we provide a brief overview of the history and the various receptors that mediate bile acid signaling in addition to its crosstalk with the gut microbiota.

Dynamics of the enterohepatic circulation of bile acids in healthy humans

Regulation of bile acid metabolism is normally discussed as the regulation of bile acid synthesis, which serves to compensate for intestinal loss in order to maintain a constant pool size. After a meal, bile acids start cycling in the enterohepatic circulation. Farnesoid X receptor-dependent ileal and hepatic processes lead to negative feedback inhibition of bile acid synthesis. When the intestinal bile acid flux decreases, the inhibition of synthesis is released. The degree of inhibition of synthesis and the mechanism and degree of activation are still unknown. Moreover, in humans, a biphasic diurnal expression pattern of bile acid synthesis has been documented, indicating maximal synthesis around 3 PM and 9 PM. Quantitative data on the hourly synthesis schedule as compensation for intestinal loss are lacking. In this review, we describe the classical view on bile acid metabolism and present alternative concepts that are based on the overlooked feature that bile acids transit through the enterohepatic circulation very rapidly. A daily profile of the cycling and total bile acid pool sizes and potential controlled and uncontrolled mechanisms for synthesis are predicted. It remains to be elucidated by which mechanism clock genes interact with the Farnesoid X receptor-controlled regulation of bile acid synthesis. This mechanism could become an attractive target to enhance bile acid synthesis at night, when cholesterol synthesis is high, thus lowering serum LDL-cholesterol.

Molecular Physiology of Bile Acid Signaling in Health, Disease, and Aging

Over the past two decades, bile acids (BAs) have become established as important signaling molecules that enable fine-tuned inter-tissue communication from the liver, their site of production, over the intestine, where they are modified by the gut microbiota, to virtually any organ, where they exert their pleiotropic physiological effects. The chemical variety of BAs, to a large extent determined by the gut microbiome, also allows for a complex fine-tuning of adaptive responses in our body. This review provides an overview of the mechanisms by which BA receptors coordinate several aspects of physiology and highlights new therapeutic strategies for diseases underlying pathological BA signaling.

The Pharmacology of Bile Acids and Their Receptors

This review provides a historical perspective of bile acids and their receptors as therapeutic targets. Bile acids are atypical steroids generated by the liver from cholesterol and have been used for almost half a century for treating liver and biliary disorders. Since the early 1970s of the last century, chenodeoxycholic acid (CDCA), a primary bile acid, and ursodeoxycholic acid (UDCA), a secondary bile acid and the 7βepimer of CDCA, have been shown effective in promoting the dissolution of cholesterol gallstones. However, lack of activity and side effects associated with the use of CDCA, along with the advent of laparoscopic cholecystectomy, have greatly reduced the clinical relevance of this application. At the turn of the century, however, the discovery that bile acids activate specific receptors, along with the discovery that those receptors are placed at the interface of the host and intestinal microbiota regulating physiologically relevant enterohepatic and entero-pancreatic axes, has led to a "bile acid renaissance." Similarly to other steroids, bile acids bind and activate both cell surface and nuclear receptors, including the bile acid sensor farnesoid X receptor (FXR) and a G-protein-coupled bile acid receptor, known as GPBAR1 (TGR5). Both receptors have been proved druggable, and several highly potent, selective, and nonselective ligands for the two receptors have been discovered in the last two decades. Currently, in addition to obeticholic acid, a semisynthetic derivative of CDCA and the first in class of FXR ligands approved for clinical use, either selective or dual FXR and GPBAR1 ligands, have been developed, and some of them are undergoing pre-approval trials. The effects of FXR and GPBAR1 ligands in different therapeutic area are reviewed.

UDCA, NorUDCA, and TUDCA in Liver Diseases: A Review of Their Mechanisms of Action and Clinical Applications

Bile acids (BAs) are key molecules in generating bile flow, which is an essential function of the liver. In the last decades, there have been great advances in the understanding of BA physiology, and new insights have emerged regarding the role of BAs in determining cell damage and death in several liver diseases. This new knowledge has helped to better delineate the pathophysiology of cholestasis and the adaptive responses of hepatocytes to cholestatic liver injury as well as of the mechanisms of injury of biliary epithelia. In this context, therapeutic approaches for liver diseases using hydrophilic BA (i.e., ursodeoxycholic acid, tauroursodeoxycholic, and, more recently, norursodeoxycholic acid), have been revamped. In the present review, we summarize current experimental and clinical data regarding these BAs and its role in the treatment of certain liver diseases.

Chenodeoxycholic Acid from Bile Inhibits Influenza A Virus Replication via Blocking Nuclear Export of Viral Ribonucleoprotein Complexes

Influenza A virus (IAV) infection is still a major global threat for humans, especially for the risk groups: young children and the elderly. The currently licensed antiviral drugs target viral factors and are prone to viral resistance. In recent years, a few endogenous small molecules from host, such as estradiol and omega-3 polyunsaturated fatty acid (PUFA)-derived lipid mediator protection D1 (PD1), were demonstrated to be capable of inhibiting IAV infection. Chenodeoxycholic acid (CDCA), one of the main primary bile acids, is synthesized from cholesterol in the liver and classically functions in emulsification and absorption of dietary fats. Clinically, CDCA has been used in the treatment of patients with cholesterol gallstones for more than five decades. In this study, we showed that CDCA attenuated the replication of three subtypes of influenza A virus, including a highly pathogenic H5N1 strain, in A549 and MDCK cell cultures with IC₅₀ ranging from 5.5 to 11.5 μM. Mechanistically, CDCA effectively restrained the nuclear export of viral ribonucleoprotein (vRNP) complexes. In conclusion, as an endogenous physiological small molecule, CDCA can inhibit IAV replication in vitro, at least in part, by blocking vRNP nuclear export, and affords further studies for development as a potential antiviral agent against IAV infections.

Treatment with the natural FXR agonist chenodeoxycholic acid reduces clearance of plasma LDL whilst decreasing circulating PCSK9, lipoprotein(a) and apolipoprotein C-III

BACKGROUND

The natural farnesoid X receptor (FXR) agonist chenodeoxycholic acid (CDCA) suppresses hepatic cholesterol and bile acid synthesis and reduces biliary cholesterol secretion and triglyceride production. Animal studies have shown that bile acids downregulate hepatic LDL receptors (LDLRs); however, information on LDL metabolism in humans is limited.

METHODS

Kinetics of autologous ¹²⁵ I-LDL were determined in 12 male subjects at baseline and during treatment with CDCA (15 mg kg^-1 day^-1 ). In seven patients with gallstones treated with CDCA for 3 weeks before cholecystectomy, liver biopsies were collected and analysed for enzyme activities and for specific LDLR binding. Serum samples obtained before treatment and at surgery were analysed for markers of lipid metabolism, lipoproteins and the LDLR modulator proprotein convertase subtilisin/kexin type 9 (PCSK9).

RESULTS

Chenodeoxycholic acid treatment increased plasma LDL cholesterol by ~10% as a result of reduced clearance of plasma LDL-apolipoprotein (apo)B; LDL production was somewhat reduced. The reduction in LDL clearance occurred within 1 day after initiation of treatment. In CDCA-treated patients with gallstones, hepatic microsomal cholesterol 7α-hydroxylase and HMG-CoA reductase activities were reduced by 83% and 54%, respectively, and specific LDLR binding was reduced by 20%. During treatment, serum levels of fibroblast growth factor 19 and total and LDL cholesterol increased, whereas levels of 7α-hydroxy-4-cholesten-3-one, lathosterol, PCSK9, apoA-I, apoC-III, lipoprotein(a), triglycerides and insulin were reduced.

CONCLUSIONS

Chenodeoxycholic acid has a broad influence on lipid metabolism, including reducing plasma clearance of LDL. The reduction in circulating PCSK9 may dampen its effect on hepatic LDLRs and plasma LDL cholesterol. Further studies of the effects of other FXR agonists on cholesterol metabolism in humans seem warranted, considering the renewed interest for such therapy in liver disease and diabetes.

Efficacy of Magnesium Trihydrate of Ursodeoxycholic Acid and Chenodeoxycholic Acid for Gallstone Dissolution: A Prospective Multicenter Trial

Background/Aims

Cholecystectomy is necessary for the treatment of symptomatic or complicated gallbladder (GB) stones, but oral litholysis with bile acids is an attractive alternative therapeutic option for asymptomatic or mildly symptomatic patients. This study was conducted to evaluate the efficacy of magnesium trihydrate of ursodeoxycholic acid (UDCA) and chenodeoxycholic acid (CDCA) on gallstone dissolution and to investigate improvements in gallstone-related symptoms.

Methods

A prospective, multicenter, phase 4 clinical study to determine the efficacy of orally administered magnesium trihydrate of UDCA and CDCA was performed from January 2011 to June 2013. The inclusion criteria were GB stone diameter ≤15 mm, GB ejection fraction ≥50%, radiolucency on plain X-ray, and asymptomatic/mildly symptomatic patients. The patients were prescribed one capsule of magnesium trihydrate of UDCA and CDCA at breakfast and two capsules at bedtime for 6 months. The dissolution rate, response rate, and change in symptom score were evaluated.

Results

A total of 237 subjects were enrolled, and 195 subjects completed the treatment. The dissolution rate was 45.1% and the response rate was 47.2% (92/195) after 6 months of administration of magnesium trihydrate of UDCA and CDCA. Only the stone diameter was significantly associated with the response rate. Both the symptom score and the number of patients with symptoms significantly decreased regardless of stone dissolution. Adverse events necessitating discontinuation of the drug, surgery, or endoscopic management occurred in 2.5% (6/237) of patients.

Conclusions

Magnesium trihydrate of UDCA and CDCA is a well-tolerated bile acid that showed similar efficacy for gallstone dissolution and improvement of gallstone-related symptoms as that shown in previous studies.

Comparison on Response and Dissolution Rates Between Ursodeoxycholic Acid Alone or in Combination With Chenodeoxycholic Acid for Gallstone Dissolution According to Stone Density on CT Scan: Strobe Compliant Observation Study

Medical dissolution of gallstone is usually performed on radiolucent gallstones in a functioning gallbladder. However, absence of visible gallstone on plain abdominal x-ray does not always preclude calcification. This study aims to compare the response and dissolution rates between ursodeoxycholic acid (UDCA) alone or in combination with chenodeoxycholic acid (CDCA) according to stone density on computed tomography (CT) scan. A total of 126 patients underwent dissolution therapy with either UDCA alone or combination of CDCA and UDCA (CNU) from December 2010 to March 2014 at Korea University Ansan Hospital. In the end, 81 patients (CNU group = 44, UDCA group = 37) completed dissolution therapy for 6 months. Dissolution rate (percentage reduction in the gallstone volume) and response to therapy (complete dissolution or partial dissolution defined as reduction in stone volume of >50%) were compared between the 2 groups. Dissolution and response rates of sludge was also compared between the 2 groups. The overall response rate was 50.6% (CNU group 43.2% vs UDCA group 59.5%, P = 0.14), and the overall dissolution rate was 48.34% (CNU group 41.5% vs UDCA group 56.5%, P = 0.13). When analyzed according to stone density, response rate was 33.3%, 87.1%, 30.0%, and 6.2% for hypodense, isodense, hyperdense, and calcified stones, respectively. Response rate (85.7% vs 88.2%, P = 0.83) and dissolution rate (81.01% vs 85.38%, P = 0.17) of isodense stones were similar between CNU and UDCA group. When only sludge was considered, the overall response rate was 87.5% (CNU group 71.4% vs UDCA group 94.1%, P = 0.19), and the overall dissolution rate was 85.42% (CNU group 67.9% vs UDCA group 92.7%, P = 0.23). Patients with isodense gallstones and sludge showed much better response to dissolution therapy with CNU and UDCA showing comparable efficacy. Therefore, CT scan should be performed before medication therapy if stone dissolution is intended.

Key discoveries in bile acid chemistry and biology and their clinical applications: history of the last eight decades

During the last 80 years there have been extraordinary advances in our knowledge of the chemistry and biology of bile acids. We present here a brief history of the major achievements as we perceive them. Bernal, a physicist, determined the X-ray structure of cholesterol crystals, and his data together with the vast chemical studies of Wieland and Windaus enabled the correct structure of the steroid nucleus to be deduced. Today, C24 and C27 bile acids together with C27 bile alcohols constitute most of the bile acid "family". Patterns of bile acid hydroxylation and conjugation are summarized. Bile acid measurement encompasses the techniques of GC, HPLC, and MS, as well as enzymatic, bioluminescent, and competitive binding methods. The enterohepatic circulation of bile acids results from vectorial transport of bile acids by the ileal enterocyte and hepatocyte; the key transporters have been cloned. Bile acids are amphipathic, self-associate in solution, and form mixed micelles with polar lipids, phosphatidylcholine in bile, and fatty acids in intestinal content during triglyceride digestion. The rise and decline of dissolution of cholesterol gallstones by the ingestion of 3,7-dihydroxy bile acids is chronicled. Scientists from throughout the world have contributed to these achievements.

Glucose-lowering effects of intestinal bile acid sequestration through enhancement of splanchnic glucose utilization

Intestinal bile acid (BA) sequestration efficiently lowers plasma glucose concentrations in type 2 diabetes (T2D) patients. Because BAs act as signaling molecules via receptors, including the G protein-coupled receptor TGR5 and the nuclear receptor FXR (farnesoid X receptor), to regulate glucose homeostasis, BA sequestration, which interrupts the entero-hepatic circulation of BAs, constitutes a plausible action mechanism of BA sequestrants. An increase of intestinal L-cell glucagon-like peptide-1 (GLP-1) secretion upon TGR5 activation is the most commonly proposed mechanism, but recent studies also argue for a direct entero-hepatic action to enhance glucose utilization. We discuss here recent findings on the mechanisms of sequestrant-mediated glucose lowering via an increase of splanchnic glucose utilization through entero-hepatic FXR signaling.

Bile acid receptors as targets for the treatment of dyslipidemia and cardiovascular disease

Dyslipidemia is an important risk factor for cardiovascular disease (CVD) and atherosclerosis. When dyslipidemia coincides with other metabolic disorders such as obesity, hypertension, and glucose intolerance, defined as the metabolic syndrome (MS), individuals present an elevated risk to develop type 2 diabetes (T2D) as well as CVD. Because the MS epidemic represents a growing public health problem worldwide, the development of therapies remains a major challenge. Alterations of bile acid pool regulation in T2D have revealed a link between bile acid and metabolic homeostasis. The bile acid receptors farnesoid X receptor (FXR) and TGR5 both regulate lipid, glucose, and energy metabolism, rendering them potential pharmacological targets for MS therapy. This review discusses the mechanisms of metabolic regulation by FXR and TGR5 and the utility relevance of natural and synthetic modulators of FXR and TGR5 activity, including bile acid sequestrants, in the treatment of the MS.

Toxicity order of cholanic acids using an immobilised cell biosensor

There is considerable published evidence of the use of cells of various species to evaluate the toxicity of numerous compounds, many of pharmaceutical interest. The coupling of cell colonies with a suitable transduction device has led to the development in recent years of toxicity biosensors based on the alteration of a process or a cell metabolic function by the toxic substance under examination. A biosensor based on immobilised yeast cells (Saccharomyces cerevisiae) has been developed recently in this department for the purpose of performing a rapid toxicity test in aqueous environmental matrices. This biosensor has now been used in the toxicity screening of a number of sodium salts of conjugated and free cholanic acids. The "toxicity degree" scale, which was found by placing in decreasing order the values of the slopes of the straight lines obtained by quantifying changes in the behaviour of the respirometric curve, plotted before and after incubation, using known concentrations of cholanic acid sodium salts, was: deoxycholic acid > chenodeoxycholic acid > ursodeoxycholic acid > cholic acid, for free cholanic acids; and glycodeoxycholic acid > glycochenodeoxycholic acid > glycocholic acid, for glycocholanic acids. These values are in good agreement with published toxicity data obtained in vitro. This sensor can thus be considered to provide a valid instrument for the preliminary evaluation of the toxicity of organic compounds or drugs.

IV chenodeoxycholate prevents calcium bilirubinate gallstones during total parenteral nutrition in the prairie dog

BACKGROUND

The purpose of this study was to determine whether IV chenodeoxycholate (CDC) could prevent total parenteral nutrition (TPN)-associated pigmented gallstones in the prairie dog.

METHODS

Twelve prairie dogs were divided into two equal groups, each receiving an identical TPN regimen. Each animal received 92 kcal/d with 61% of the calories from carbohydrate. The total volume of infusate delivered to each animal was 59 mL/d. Animals in one group, termed the TPN + CDC group, received a daily bolus injection of CDC at a dose of 15 mg/kg. Prairie dogs in the second group, termed the TPN group, received water (vehicle carrier) 1 mL/kg/d. The TPN and TPN + CDC groups received TPN for 40.3 +/- 1.3 and 42.5 +/- 0.6 days, respectively.

RESULTS

There was no statistical difference in the initial and final weights between the two groups. None of the TPN + CDC-treated animals had gallstones or calcium bilirubinate crystals. In contrast, all of the TPN-treated animals had calcium bilirubinate crystals (p = .002), and five of six had macroscopic black pigmented gallstones (p = .015). Cholesterol crystals were not observed in either group of animals. The amount of biliary bilirubin and ionized calcium was significantly greater in the TPN group (both p < .001); however, both groups had a similar total biliary calcium concentration.

CONCLUSION

IV CDC is effective in preventing TPN-associated gallstones in the prairie dog.

Cholanic acids determined in commercial drugs by means of a new ISFET device

An ISFET device selective for cholanic acids, based on a PVC-sebacate membrane, containing benzyldimethylcetylammoniumcholate as exchanger, has been prepared, characterized and applied to the determination of cheno or ursodeoxycholic acid content of commercial pharmaceutical drugs and critical micellar concentration (CMC) values for cholate, deoxycholate and chenodeoxycholate. The results are compared with those obtained using previously described polymeric membrane sensors based on the same exchanger.

Transhepatic topical dissolution of gallbladder stones with MTBE and EDTA. Results, side effects, and correlation with CT imaging

Forty-two patients with symptomatic gallstones (28 women, 14 men, mean age 49.8 +/- 13.2 years) were recruited for contact dissolution therapy. Pretreatment CT scans of the gallbladder were obtained in every patient under standard conditions. For contact dissolution treatment of heterogeneous gallstones or gallstones with attenuation values of more than 50 Hounsfield units, methyl tert-butyl ether and bile acid ethylene diaminetetraacetic acid were used in alternating administration at time intervals and durations adapted to the individual tolerance of the patients. In the case of gallstones with mean attenuation values under 50 Hounsfield units, the dissolution therapy was performed with methyl tert-butyl ether alone. In 12 (28.6%) patients a complete dissolution of gallbladder stones could be achieved; 11 patients (26.2%) revealed gallbladder sludge but no radiologically or sonographically visualized residual stone debris. The remaining 19 (45.2%) patients had residual gallstone debris. Shell fragments in three of five rimmed gallstones, seven of eight laminated gallstones, and all densely calcified stones were refractory to contact dissolution therapy. Dissolution rates correlated well with mean attenuation values, whereas no significant correlation was found between stone number and dissolution rates or between stone diameter and dissolution rates respectively. The mean instillation time required for stones with a mean density of more than 50 HU was 17.7 +/- 11.5 hr of bile acid ethylene diaminetetraacetic acid and 5.8 +/- 3.2 hr of methyl tert-butyl ether. In the case of isodense stones, the average instillation time of methyl tert-butyl ether was 12.3 +/- 4.7 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of bile acid therapy for gallstone dissolution: a meta-analysis of randomized trials

To define better the efficacy of bile acid therapy for dissolution of radiolucent gallstones, we performed a meta-analysis of published trials from January 1966 to September 1992. Studies were identified using a MEDLINE computer search followed by an extensive manual search. The inclusion criteria used were: randomized trial, radiolucent gallstones in a visualizing gallbladder on oral cholecystography, and complete stone dissolution confirmed by oral cholecystography or ultrasound. Study results were pooled into 6 groups: placebo: high- and low-dose chenodeoxycholic acid (CDCA) (> or = 10 mg.kg/day and < 10 mg.kg/day); high- and low-dose ursodeoxycholic acid (UDCA) (> or = 7 mg.kg/day and < 7 mg.kg/day) and combined CDCA plus UDCA. Homogeneity calculations were performed and the percentage of complete stone dissolution calculated for each group with 95% confidence intervals. Of 66 trials identified, 23 comprising 1949 patients met the inclusion criteria. A total of 1062 patients were treated with CDCA, 819 with UDCA and 78 combination therapy. In studies > 6 months' duration, high-dose UDCA completely dissolved stones in 37.3% of patients (95% C.I. 33-42%), low-dose UDCA in 20.6%) and high-dose CDCA 18.2% (95% C.I. 15-21%). Based on only two studies, combination therapy achieved dissolution in 62.8% (95% C.I. 51-74%) of patients. Stones less than 10 mm dissolved significantly more frequently than stones larger than 10 mm. This analysis shows that UDCA in doses greater than 7 mg.kg/day taken for greater than 6 months will dissolve radiolucent gallstones in 38% of patients. The combination of UDCA and CDCA may be more efficacious but this observation is based upon only 78 patients and requires confirmation in further randomized trials.

Gallbladder stones: shockwave therapy

Within the past 7 years, gallbladder lithotripsy by shockwaves has been proven to be a safe and effective non-invasive therapy for selected patients with gallstone disease. While regulatory decisions prevent shockwave therapy from being used more frequently in the USA, the number of patients treated in Europe and Asia is increasing constantly. At our institution, a relatively constant number of about 250 new patients per year have been treated since 1988 (Figure 4). About 20% of patients with gallstones are suitable for shockwave therapy according to present criteria. The rate of evacuation of all fragments is determined by the initial stone number and stone size, the success at stone fragmentation, adjuvant bile acid dissolution therapy, and gallbladder contractility. In contrast to laparoscopic cholecystectomy (Dubois et al, 1989; Perissat et al, 1989; Southern Surgeons Club, 1991), shockwave therapy does not require general anaesthesia. And in contrast to direct contact dissolution therapy of gallbladder stones using MTBE (Thistle et al, 1989), lithotripsy is non-invasive. In the majority of patients, complete fragment disappearance takes several months. Preliminary analyses of the cost-effectiveness of lithotripsy have revealed that lithotripsy, including retreatments and bile acid medication for recurrent stones, costs about as much as open cholecystectomy (Rothschild et al, 1990; Bass et al, 1991). The ideal patient for gallbladder lithotripsy has a single radiolucent stone < or = 20-25 mm in diameter in a functioning gallbladder (Figure 1). In patients with such stones, nearly all studies have confirmed a favourable outcome with rapid clearance of all fragments and a relatively low rate of stone recurrence. For carefully selected patients, extracorporeal shockwave lithotripsy is therefore an attractive non-invasive therapy.

Gallstones during octreotide therapy

Gallbladder stones (GBS) are found in up to 50% of patients receiving octreotide, but the reported prevalence of cholecystolithiasis in patients treated with octreotide is variable and little is known about gallstone incidence, composition, pathogenetic mechanisms, dissolvability, and primary prevention. Octreotide treatment apart, in industrialised societies most GBS are mixed in composition, cholesterol-rich (arbitrarily greater than 70% cholesterol by weight), radiolucent (70%), and, given a patent cystic duct (70%), dissolvable in bile rendered unsaturated in cholesterol by oral ursodeoxycholic (UDCA) +/- chenodeoxycholic (CDCA) acid treatment. They form when (1) GB bile becomes supersaturated with cholesterol (as the molar ratio of cholesterol to phospholipids in biliary vesicles approaches 1:1, the vesicles become unstable); (2) there is an imbalance between pro- and anti-nucleating factors, which favors cholesterol crystal precipitation; and (3) there is stasis within the GB as a result of altered motor function and/or excess mucus that traps the crystals. These changes may be associated with altered (4) biliary bile acid composition (more DCA and less CDCA than normal), and/or (5) phospholipid fatty acid composition (arachidonyl-rich lecithin acting as a substrate for mucosal prostaglandin synthesis which, in turn, may influence both gallbladder motility, and mucus glycoprotein synthesis and secretion). During octreotide treatment, meal-stimulated cholecystokinin (CCK) release is impaired leading to GB hypomotility, but little is known about the effects of octreotide on biliary cholesterol saturation, crystal nucleation time, mucus glycoprotein concentration, bile acid or phospholipid fatty acid composition. Most, but not all, reports suggest that the prevalence of GBS in octreotide-treated patients is considerably greater than that in age-, sex-, and weight-matched controls, but proof (by pre-treatment and on-treatment ultrasound) that the GBS were absent before, but developed during, therapy is not always available. Furthermore, there are few data on analysis of GBS composition in patients developing stones during treatment, although initial reports suggest that octreotide-associated GBS are also radiolucent, cholesterol-rich, and dissolve with oral bile acid treatment. Maximum GBS attenuation values, measured in Hounsfield Units (HU) by localized computerized tomography scanning of the GB, predict stone composition and dissolvability: GBS with scores of less than 100 HU are cholesterol-rich and dissolve well with oral bile acid treatment. However, preliminary results in 11 acromegalic patients treated with 200 to 600 micrograms octreotide/d for 29 to 68 months show that the HU scores range from 23 to 490 (mean +/- SEM, 116 +/- 41), suggesting that at least four of these 11 patients have non-cholesterol stones.(ABSTRACT TRUNCATED AT 400 WORDS)

Noninvasive therapy of gallbladder calculi with a radiopaque rim

Safety and efficacy of shock-wave lithotripsy and bile acid dissolution therapy of patients with gallbladder calculi with a radiopaque rim were evaluated. Eighty-six patients with symptomatic solitary stones were treated by this noninvasive therapy and were followed up to 18 months. Three different lithotripsy treatment modalities were used. Up to 1600 shock wave discharges were applied. Patients in group A (n = 20) were treated with an electrohydraulic water-bath lithotripter at a discharge voltage of 18 +/- 1 kV (mean +/- SD), group B patients (n = 25) were treated with an electrohydraulic water-cushion lithotripter at 19 +/- 2 kV, and group C patients were treated (n = 41) with the same lithotripter at 22 +/- 2 kV. Five to eight months after lithotripsy, 15% in group A were free of fragments compared with only 4% in group B (NS vs. group A), and 38% in group C had no stones (NS vs. group A; P = 0.007 vs. B). Thirteen to eighteen months after lithotripsy, the respective results were 59% in group A, 37% in group B (NS vs. group A), and 68% in group C (NS vs. group A; P = 0.05 vs. group B). Patients with fragments of less than or equal to 3 mm in diameter showed significantly better fragment clearance than those with larger fragments. The frequency of adverse effects was not significantly different between the three groups. Biliary colic occurred in 43% of the patients and mild biliary pancreatitis in 3 patients. Endoscopic sphincterotomy was required in 1 patient, and elective cholecystectomy was performed in 6 patients. Using a water-cushion lithotripter at high-power setting, selected patients with solitary gallbladder stones with a radiopaque rim may be treated safely and successfully by shock-wave lithotripsy combined with bile acid dissolution therapy.

Pathophysiology and pharmacotherapy of cholelithiasis

Several factors are involved in the development of gallstone formation: formation of supersaturated bile; nucleation; formation, retention and adhesion of cholesterol crystals and eventually stone growth. The dynamics of the gallbladder may play a key role in the overall process. The pathophysiologic theory of cholesterol gallstone formation and the knowledge of their physico-chemical properties support the modern concept of gallstone therapy. Chenodeoxycholic and ursodeoxycholic have been widely used as cholesterol gallstone dissolving agents and evaluated in terms of efficacy and safety.

Gallbladder stones--dissolve, blast, or extract? Laparoscopic cholecystectomy versus 'the rest'

This article reviews selected aspects of the non-surgical/minimally invasive treatments of gallbladder stones (GBS) and discusses briefly the residual role of these treatments in the era of laparoscopic cholecystectomy. In patients with specific, gallstone-related symptoms who wish to retain their 'functioning' gallbladders, there are at least six different management options. They range from rapid but invasive to slow but safe: i) the rotary lithotrite; ii) percutaneous cholecystolithotomy; iii) percutaneous transhepatic or iv) endoscopic retrograde cannulation of the gallbladder followed by instillation (manual or pump-assisted) of contact solvents; v) extracorporeal shock-wave lithotripsy + adjuvant bile acids and; vi) oral bile acids alone. The recommended investigation sequence is i) ultrasound (to diagnose the presence of GBS), followed by ii) oral cholecystography (to assess cystic duct patency, gallbladder anatomy and GBS size, number, lucency, buoyancy, and contour), and iii) regional computed tomography scanning of the gallbladder (to predict stone composition and dissolvability and to plan routes of access to the gallbladder). The decision-making steps are i) choice of some form of active treatment versus no treatment (other than observation); ii) in those with specific symptoms and a patent cystic duct who opt for active treatment, to choose between removing versus retaining the gallbladder; and iii) in those who wish to retain their 'functioning' gallbladder, to offer and select the most appropriate of the alternative options. In conclusion, despite the excellence of laparoscopic cholecystectomy, there remains a place for the non-surgical/minimally invasive approaches in a carefully selected minority of symptomatic GBS patients. Although GBS may recur in approximately 50% of patients, the recurrent stones are often asymptomatic, can be detected 'early' by follow-up ultrasound, and are easily treated. Ultimately, the aim of gallstone research must be to prevent not only recurrent but also primary GBS formation, which would obviate the need for both medical and surgical treatment.

Replacement of cholesterol gallstones by murideoxycholyl taurine gallstones in prairie dogs fed murideoxycholic acid

The effect of two hydrophilic bile acids, murideoxycholic acid (3 alpha,6 beta-dihydroxy-5 beta-cholanoic acid) and ursodeoxycholic acid, on cholesterol and bile acid metabolism and hepatic pathology and gallstone composition was studied in the prairie dog. Cholesterol gallstones were induced by feeding a diet containing 1.2% cholesterol for 75 days. The animals were divided into six groups, and gallstone regression was studied as follows: groups 2 and 5, chow plus 0.2% cholesterol; groups 3 and 6, chow plus 0.2% cholesterol plus 0.15% ursodeoxycholic acid; groups 4 and 7, chow plus 0.2% cholesterol plus 0.15% murideoxycholic acid. Animals in groups 2 to 4 were killed after an additional 6 wk; animals in groups 5 to 7 were killed after an additional 12 wk. Gallstone dissolution did not occur in any group. The gallstones in groups 2, 3, 5 and 6 were typical cholesterol aggregates, as determined by polarized light microscopy and Fourier transform infrared spectrometry. The gallstones of the murideoxycholic acid group were large, solitary, dark stones that appeared radiopaque under 22 kVp x-ray examination. Scanning electron microscopy showed that in these stones the cholesterol crystals had been replaced by an amorphous material, both within the stone and on the stone surface. Chemical analysis indicated that at the end of 12 wk the calcium/sodium salt of the taurine conjugate of murideoxycholic acid (murideoxycholyl taurine) comprised 70% of the stones; protein, cholesterol and small amounts of other bile salts were also present. In vitro studies confirmed the insolubility of the sodium and calcium salts of murideoxycholyl taurine. These studies indicate that the hydrophilic bile acids, murideoxycholic acid and ursodeoxycholic acid, did not achieve gallstone dissolution under the conditions used. In the animals fed murideoxycholic acid, an insoluble calcium salt of murideoxycholyl taurine replaced cholesterol as the major constituent of gallbladder stones. This is the first example of an insoluble dihydroxy taurine-conjugated bile acid; administration of the unconjugated bile acid induced precipitation of a kind of gallstone not previously reported. The final result was transformation of cholesterol stones to bile salt stones.

Nucleation time, cholesterol saturation index, and biliary bile acid pattern. A comparison in responders and nonresponders to systemic litholysis with bile acids

In a 24-month trial of a combination therapy with ursodeoxycholic acid and chenodeoxycholic acid complete dissolution of radiolucent gallstones was achieved in 15 of 55 patients (27.3%). A decrease of stone volume of greater than 35% was achieved in a further 28 patients (50.9%). In 12 patients (21.8%) inadequate compliance (3.6%), a nonfunctioning gallbladder (3.6%), absence of size decrease (10.9%), or acute cholecystitis (3.6%) required interruption of therapy. Determination of the cholesterol saturation index (CSI) did not facilitate patient selection, nor was there a statistically significant difference between responders and nonresponders to dissolution therapy. In the course of treatment the average CSI showed a statistically significant decrease from 1.54 +/- 0.12 to 0.82 +/- 0.06 (p less than 0.001). Patients in whom complete dissolution was achieved and those in whom no improvement was observed differed significantly in nucleation time (4.7 +/- 0.8 versus 15.0 +/- 2.2 days; p less than 0.001) and initial gallstone volume (274 +/- 78 versus 1045 +/- 180 mm3). The nucleation time increased statistically significantly during the therapy in the successfully treated group. The percentages of glycocholic acid (8.1 +/- 1.13 versus 4.1 +/- 0.55%; p less than 0.01), taurocholic acid (2.2 +/- 0.45 versus 0.8 +/- 0.23%; p less than 0.05), and glycodeoxycholic acid (4.9 +/- 0.70 versus 1.4 +/- 0.37%; p less than 0.001) were statistically significantly different after the treatment. There were no statistically significant differences between patients with complete and incomplete stone dissolution with regard to age, mean body weight, or laboratory variables.

The prevention of cholelithiasis with infused sodium chenodeoxycholate in the prairie dog (Cynomys ludovicianus)

1. This study examines the efficacy of infused sodium chenodeoxycholate to prevent cholesterol gallstone formation in the prairie dog when fed a high cholesterol diet. 2. Three experimental groups were designed to examine this. The first group (N = 5) was fed a normal rat chow diet, the second group (N = 5) was fed a high cholesterol diet (0.4% cholesterol by weight), and the third group (N = 5) was fed a high cholesterol diet plus given a daily injection of intravenous sodium chenodeoxycholate (15 mg/kg). 3. All of the animals in the second group had cholesterol crystals and cholesterol gallstones. In the third group, none of the animals had gallstones, and all but one lacked cholesterol crystals. 4. Statistical analysis showed that the first and third groups were statistically identical in their lithogenic indices and biliary lipid composition. 5. We concluded that infused sodium chenodeoxycholate is effective in preventing cholesterol gallstone formation in the prairie dog when fed a high cholesterol diet.

Intrahepatic cholesterol stones: a rationale for dissolution therapy

A case of primary cholesterol hepatolithiasis is reported. Stone composition was documented by infrared spectroscopy, and the presence of cholesterol saturated bile was demonstrated using standard biochemical techniques. The patient was treated with operative stone extraction, choledochoscopy, biliary enteric anastomosis, and oral dissolution therapy. The administration of oral dissolution agents has altered the composition of the patient's bile and may prevent further stone formation. We advocate the use of both stone and biliary biochemical analysis for patients with primary hepatolithiasis to facilitate optimal therapy.

Gallstone dissolution

Many methods are available for gallstone dissolution, including oral bile salts; cholesterol solvents such as mono-octanoin or methyl tert-butyl either; and calcium or pigment solvents such as EDTA and polysorbate. Which of these approaches will be appropriate for an individual patient depends on the type of stones; whether they are in the gallbladder or the bile ducts; whether access to the biliary tree is available; the patient's age and general medical condition; and the availability of necessary expertise. In the US, both chenodeoxycholate and ursodeoxycholate are now available. Ursodeoxycholate is more expensive but appears to produce fewer side effects and may be more efficacious. These agents are most effective in thin women with small floating, radiolucent cholesterol stones in a functioning gallbladder. Only about half of the small subset of patients will experience partial or complete dissolution of stones within a year. Stone recurrence and the potential toxicity of long-term therapy are problems with this approach. Therefore, for most patients, cholecystectomy, either in the traditional fashion or using a laparoscopic approach (see article later in this issue by Gadacz et al), is the most cost-effective and perhaps the safest option. Intragallbladder instillation of methyl tert-butyl ether probably will be applicable only to a small subset of patients, and treatment is likely to be followed by a high recurrence rate. In patients with retained common duct cholesterol stones and access to the biliary tree, mono-octanoin therapy is advantageous in that it can be initiated as soon as cholangiography demonstrates no extravasation. In properly selected patients, a 90% success rate with this technique can be expected within 7 days.

Effect of chronic ursocholic acid administration on bile lipid composition and bile acid pool size in gallstone patients

We assessed the effect of chronic (4-6 weeks) administration of ursocholic acid (UCA) (15 mg/kg/day), a natural bile acid with poor detergent capacity, on biliary lipid composition of gallbladder bile (n = 26) and bile acid pool size (n = 5) in gallstone patients. During treatment the biliary molar percentage UCA increased from trace values to 28% (p less than 0.001). This effect was accompanied by an increase in molar percentage deoxycholic acid from 16% to 33% (p less than 0.001). Total bile acid pool size remained unchanged during UCA administration; cholic acid and chenodeoxycholic acid pool sizes decreased from 1.0 to 0.6 mmol (p less than 0.05) and from 1.6 to 0.9 mmol (p less than 0.05), respectively. The molar percentage cholesterol of gallbladder bile decreased from 9.8% to 7.0% (p less than 0.001) during UCA, but bile remained supersaturated with cholesterol in 21 patients. The weak effect on biliary lipid composition and the increase of potentially toxic deoxycholic acid in bile suggest that UCA is unlikely to replace ursodeoxycholic and chenodeoxycholic acid for medical treatment of gallstones.

Effects of bile acid depletion and of ursodeoxycholic and chenodeoxycholic acids on biliary protein secretion in the hamster

The effect of changes of both the rate of secretion and the composition of bile acids on biliary proteins was studied in a bile fistula hamster model. Biliary protein secretion as well as bile flow and bile acid secretion were studied in response to intravenous infusions of low, medium and high doses of ursodeoxycholic acid and chenodeoxycholic acid in comparison to the infusion of the normal saline carrier (control) solution. The control-infused animals showed a marked and statistically significant increase in both the concentration and total excretion of biliary proteins. All three doses of ursodeoxycholic acid either prevented the increase of protein concentration or led to its decrease. The low and medium doses of chenodeoxycholic acid had similar effects. However, the high dose of this bile acid was cholestatic and increased the biliary protein concentration. The results of the study indicate that decreases in bile acid secretion, as they occur after an interruption of the enterohepatic circulation, may lead to major increases in biliary protein concentration. The study also shows that these changes in protein secretion, which may promote nucleation, are reversed by the cholelitholytic bile acids, ursodeoxycholic acid and chenodeoxycholic acid.

Administration of a terpene mixture inhibits cholesterol nucleation in bile from patients with cholesterol gallstones

Patients with cholesterol gallstones referred to elective cholecystectomy were randomly assigned prior to operation to no treatment (n = 14), treatment with one capsule t.d.s. (n = 12) or two capsules t.d.s. (n = 11) of a terpene mixture (Rowachol). Patients with pigment stones (n = 7) or no biliary tract disease (n = 5) were also studied. Lipid composition, presence of cholesterol monohydrate crystals, and nucleation time were determined in gallbladder bile aspirated during surgery. Cholesterol saturation was similar in the different groups. Crystals were present in all cholesterol gallstone patients without treatment and in none of the controls. In one of the patients treated with one capsule and four of the patients treated with two capsules crystals could not be detected. The terpenes prolonged nucleation time from 2.8 to 5.8 days (one capsule; P less than 0.05) and to 9.5 days (two capsules; P less than 0.001), respectively; but nucleation did not occur in seven controls. Although the mechanism by which the terpene mixture inhibits the formation of cholesterol crystals in bile was not determined, the findings suggest that the terpene mixture might be a useful agent for a clinical trial to test whether they will prevent recurrence of gallstones after medical dissolution.

Solubilization of lipids from hamster bile-canalicular and contiguous membranes and from human erythrocyte membranes by conjugated bile salts

We have demonstrated in vitro the efficacy of the taurine-conjugated dihydroxy bile salts deoxycholate and chenodeoxycholate in solubilizing both cholesterol and phospholipid from hamster liver bile-canalicular and contiguous membranes and from human erythrocyte membrane. On the other hand, the dihydroxy bile salt ursodeoxycholate and the trihydroxy bile salt cholate solubilize much less lipid. The lipid solubilization by the four bile salts correlated well with their hydrophobicity: glycochenodeoxycolate, which is more hydrophobic than the tauro derivative, also solubilized more lipid. All the dihydroxy bile salts have a threshold concentration above which lipid solubilization increases rapidly; this correlates approximately with the critical micellar concentration. The non-micelle-forming bile salt dehydrocholate solubilized no lipid at all up to 32 mM. All the dihydroxy bile acids are much more efficient at solubilizing phospholipid than cholesterol. Cholate does not show such a pronounced discrimination. Lipid solubilization by chenodeoxycholate was essentially complete within 1 min, whereas that by cholate was linear up to 5 min. Maximal lipid solubilization with chenodeoxycholate occurred at 8-12 mM; solubilization by cholate was linear up to 32 mM. Ursodeoxycholate was the only dihydroxy bile salt which was able to solubilize phospholipid (although not cholesterol) below the critical micellar concentration. This similarity between cholate and ursodeoxycholate may reflect their ability to form a more extensive liquid-crystal system. Membrane specificity was demonstrated only inasmuch as the lower the cholesterol/phospholipid ratio in the membrane, the greater the fractional solubilization of cholesterol by bile salts, i.e. the total amount of cholesterol solubilized depended only on the bile-salt concentration. On the other hand, the total amount of phospholipid solubilized decreased with increasing cholesterol/phospholipid ratio in the membrane.

Agents for gallstone dissolution

Numerous methods are presently available for gallstone dissolution, including oral bile salts; cholesterol solvents such as mono-octanoin and methyl tert-butyl ether; calcium or pigment solvents such as EDTA and polysorbate; mechanical extraction techniques through a T-tube tract or after endoscopic sphincterotomy; or fragmentation methods such as ultrasonography or electrohydraulic lithotripsy, lasers, and extracorporeal shock waves. Which, if any, of these methods will be appropriate for an individual patient depends on the type of stones, whether they are in the gallbladder or bile ducts, whether access to the biliary tree is available, the patient's age and general medical condition, and the availability of expert radiologists, endoscopists, and newer equipment. In the United States, the only available oral bile salt for cholesterol gallstone dissolution is chenodeoxycholate. Ursodeoxycholate, which is more rapid and less toxic, has not been approved by the Federal Drug Administration. These agents are most effective in thin women with small, floating, radiolucent cholesterol gallstones in a functioning gallbladder. Only about half of this small subset of patients, however, will experience partial or complete dissolution of stones in 6 to 12 months. Moreover, recurrence is very likely, and the potential toxicity of long-term therapy is unknown. Thus, for most patients, cholecystectomy remains the most cost-effective and, perhaps, safest option. Intragallbladder instillation of methyl tert-butyl ether and extracorporeal shock wave therapy are also likely to be applicable to only small subsets of patients and to be associated with high recurrence rates. In patients with retained ductal cholesterol stones and access to the biliary tree, mono-octanoin therapy is advantageous in that it can be begun as soon as cholangiography demonstrates no extravasation. In properly selected patients, a 90 percent success rate with mono-octanoin infusion can be expected within a week. Radiologic or endoscopic extraction techniques require maturation of a relatively straight T-tube tract but are not dependent on the type of stone. In the hands of experts, these techniques are highly successful. In postcholecystectomy patients without access to the biliary tree, endoscopic sphincterotomy has become the preferred method of management and can be expected to succeed in more than 90 percent of patients. At this point, the exact role for ultrasonic or electrohydraulic lithotripsy and lasers is unknown. However, these techniques may be applicable in the future in patients with retained bile duct stones in whom extraction and infusion techniques have failed.

Transformation of chenodeoxycholic acid to ursodeoxycholic acid in patients with Crohn's disease

In vivo 7 beta-epimerization of chenodeoxycholic acid to ursodeoxycholic acid and the role of 7-ketolithocholic acid as an intermediate in this biotransformation were studied in 11 patients with Crohn's disease and in 5 healthy volunteers. The incorporation of deuterium into biliary ursodeoxycholic acid and 7-ketolithocholic acid was determined by computed gas chromatography-mass fragmentography after ingestion of a dideuterated chenodeoxycholic acid, chenodeoxycholic-11,12-d2 acid. The incorporation of deuterium into ursodeoxycholic acid increased to a peak level at 48 h in the patients with Crohn's disease, but was delayed in healthy volunteers. In 8 patients and 2 healthy controls there were small amounts of 7-ketolithocholic acid in bile. The incorporation of deuterium into 7-ketolithocholic acid was confirmed in only 2 patients and the peak level was noted at 48 h. These observations suggest that 7-ketolithocholic acid is an intermediate of this biotransformation in patients with Crohn's disease.

Optimum conditions for ursodeoxycholic acid production from lithocholic acid by Fusarium equiseti M41

Ursodeoxycholic acid dissolves cholesterol gallstones in humans. In the present study optimum conditions for ursodeoxycholic acid production by Fusarium equiseti M41 were studied. Resting mycelia of F. equiseti M41 showed maximum conversion at 28 degrees C, pH 8.0, and dissolved oxygen tension of higher than 60% saturation. Monovalent cations, such as Na+, K+, and Rb+, stimulated the conversion rate more than twofold. In the presence of 0.5 M KCl, the initial uptake rate and equilibrium concentration of lithocholic acid (substrate) were enhanced by 5.7- and 1.7-fold, respectively. We confirmed that enzyme activity catalyzing 7 beta-hydroxylation of lithocholic acid was induced by substrate lithocholic acid. The activity in the mycelium was controlled by dissolved oxygen tension during cultivation: with a dissolved oxygen tension of 15% and over, the activity peak appeared at 25 h of cultivation, whereas the peak was delayed to 34 and 50 h with 5 and 0% dissolved oxygen tension, respectively. After reaching the maximum, the 7 beta-hydroxylation activity in the mycelium declined rapidly at pH 7.0, but the decline was retarded by increasing the pH to 8.0. Several combinations of operations, such as pH shift (from pH 7 to 8), addition of 0.5 M KCl, and dissolved oxygen control, were applied to the production of ursodeoxycholic acid in a jar fermentor, and a much larger amount of ursodeoxycholic acid (1.2 g/liter) was produced within 96 h of cultivation.