Gallbladder emptying in vivo, bile composition, and nucleation of cholesterol crystals in patients with cholesterol gallstones

Ultrasonographic assessment of gastric and gallbladder dynamics in human health and disease

The diagnosis of functional disorders of the upper gastrointestinal tract relies on clinical evaluation after exclusion of most frequent organic diseases. Diagnostic techniques contribute to better characterization of disease, choice of specific therapy, and follow-up. Functional ultrasonography was introduced in the early '80 s for the non-invasive study of gastric and gallbladder emptying without ionizing radiation, during fasting and postprandially. This technique detects dysfunctional motility in several gastrointestinal and systemic conditions, and can be used along with the assessment of real-time satiety and gastrointestinal symptoms after food ingestion, and dosing of hormones involved in the modulation of gastrointestinal and metabolic homeostasis. Functional ultrasonography has been increasingly used to explore the gastrointestinal pathophysiology, the gut-brain interaction, the effects of drugs (such as antidiabetics), the response to specific dietary and feeding patterns, and to support the development of nutraceuticals. In this evolving scenario, ultrasonography stands as a widely available, highly sustainable, non-invasive, repeatable, safe and low-cost tool, as compared with more expensive, less sustainable or still scarcely standardized procedures to study gastric and gallbladder motility as scintigraphy, wireless motility capsule tests, 13C breath tests, or magnetic resonance imaging. Functional ultrasonography not only provides reliable data in experimental protocols, but also in the assessment of clinical conditions as dyspeptic symptoms, diabetes, gastroenteric and neurological diseases, critical illness, and as a benchmark to evaluate the gastrointestinal effects of innovative drugs.

Discovery and exploration of novel somatostatin receptor subtype 5 (SSTR5) antagonists for the treatment of cholesterol gallstones

The shortage of cholesterol gallstones treatment intensifies the need to discover of effective small molecule drugs. Clinical follow-up and studies have found that activation of somatostatin receptor subtype 5 (SSTR5) reduce gallbladder contraction and thus increase the risk of cholesterol gallstones, implying that antagonizing SSTR5 may promote gallbladder emptying and reduce the formation of gallstones. Herein, we discovered novel SSTR5 antagonists and firstly investigated its effects on cholesterol gallstone. From loperamide, a reported seed structure with micromole activity, we identified optimal compound 23 as an SSTR5 antagonist exhibiting single-digit nanomolar potency, low hERG inhibition and oral availability. Further in vivo evaluation revealed that 23 significantly promoted gallbladder emptying. Moreover, in a mouse cholesterol gallstone model, 23 (3 mg/kg) effectively reduced the cholesterol gallstones formation, showing better efficacy than the clinical first-line drug UDCA (60 mg/kg), providing a new insight into the development of anti-gallstone drugs.

Importance of the gut microbiota in mice with a 'humanized' bile acid pool

Bile acids are signaling mediators, enabling intricate communication between tissues and the gut microbiota, and are involved in the pathophysiology of several immune and metabolic disorders. In this commentary, we discuss the importance of the gut microbiota in the Cyp2c70 knock-out mice, which are considered as a promising 'humanized' experimental resource for studying bile acids and their role in pathological conditions. We also discuss how Cyp2c70-deficient mice contribute to enhancing the translatability of preclinical studies in murine models to humans.

Gallstone Formation Follows a Different Trajectory in Bariatric Patients Compared to Nonbariatric Patients

Since obese patients form cholesterol gallstones very rapidly after bariatric surgery, in patients who did not form gallstones during preceding years, we hypothesized that gallstone formation follows a different trajectory in bariatric patients compared to nonbariatric patients. We therefore analyzed the lipid composition of gallbladder bile derived from 18 bariatric gallstone patients and 17 nonbariatric gallstone patients (median (IQR) age, 46.0 (28.0-54.0) years; 33 (94%) female) during laparoscopic cholecystectomy using an enzymatic and lipidomics approach. We observed a higher concentration of total lipids (9.9 vs. 5.8 g/dL), bile acids (157.7 vs. 81.5 mM), cholesterol (10.6 vs. 5.4 mM), and phospholipids (30.4 vs. 21.8 mM) in bariatric gallstone patients compared to nonbariatric gallstone patients. The cholesterol saturation index did not significantly differ between the two groups. Lipidomics analysis revealed an interesting pattern. Enhanced amounts of a number of lipid species were found in the gallbladder bile of nonbariatric gallstone patients. Most striking was a fivefold higher amount of triglyceride. A concomitant ninefold increase of apolipoprotein B was found, suggesting secretion of triglyceride-rich lipoproteins (TRLs) at the canalicular pole of the hepatocyte in livers from nonbariatric gallstone patients. These findings suggest that gallstone formation follows a different trajectory in bariatric patients compared to nonbariatric patients. Impaired gallbladder emptying might explain the rapid gallstone formation after bariatric surgery, while biliary TRL secretion might contribute to gallstone formation in nonbariatric patients.

Bile acids in glucose metabolism and insulin signalling - mechanisms and research needs

Of all the novel glucoregulatory molecules discovered in the past 20 years, bile acids (BAs) are notable for the fact that they were hiding in plain sight. BAs were well known for their requirement in dietary lipid absorption and biliary cholesterol secretion, due to their micelle-forming properties. However, it was not until 1999 that BAs were discovered to be endogenous ligands for the nuclear receptor FXR. Since that time, BAs have been shown to act through multiple receptors (PXR, VDR, TGR5 and S1PR2), as well as to have receptor-independent mechanisms (membrane dynamics, allosteric modulation of N-acyl phosphatidylethanolamine phospholipase D). We now also have an appreciation of the range of physiological, pathophysiological and therapeutic conditions in which endogenous BAs are altered, raising the possibility that BAs contribute to the effects of these conditions on glycaemia. In this Review, we highlight the mechanisms by which BAs regulate glucose homeostasis and the settings in which endogenous BAs are altered, and provide suggestions for future research.

Recent advances in understanding and managing cholesterol gallstones

The high prevalence of cholesterol gallstones, the availability of new information about pathogenesis, and the relevant health costs due to the management of cholelithiasis in both children and adults contribute to a growing interest in this disease. From an epidemiologic point of view, the risk of gallstones has been associated with higher risk of incident ischemic heart disease, total mortality, and disease-specific mortality (including cancer) independently from the presence of traditional risk factors such as body weight, lifestyle, diabetes, and dyslipidemia. This evidence points to the existence of complex pathogenic pathways linking the occurrence of gallstones to altered systemic homeostasis involving multiple organs and dynamics. In fact, the formation of gallstones is secondary to local factors strictly dependent on the gallbladder (that is, impaired smooth muscle function, wall inflammation, and intraluminal mucin accumulation) and bile (that is, supersaturation in cholesterol and precipitation of solid crystals) but also to "extra-gallbladder" features such as gene polymorphism, epigenetic factors, expression and activity of nuclear receptors, hormonal factors (in particular, insulin resistance), multi-level alterations in cholesterol metabolism, altered intestinal motility, and variations in gut microbiota. Of note, the majority of these factors are potentially manageable. Thus, cholelithiasis appears as the expression of systemic unbalances that, besides the classic therapeutic approaches to patients with clinical evidence of symptomatic disease or complications (surgery and, in a small subgroup of subjects, oral litholysis with bile acids), could be managed with tools oriented to primary prevention (changes in diet and lifestyle and pharmacologic prevention in subgroups at high risk), and there could be relevant implications in reducing both prevalence and health costs.

An update on the pathogenesis of cholesterol gallstone disease

PURPOSE OF REVIEW

Gallstone disease is a major epidemiologic and economic burden worldwide, and the most frequent form is cholesterol gallstone disease.

RECENT FINDINGS

Major pathogenetic factors for cholesterol gallstones include a genetic background, hepatic hypersecretion of cholesterol, and supersaturated bile which give life to precipitating cholesterol crystals that accumulate and grow in a sluggish gallbladder. Additional factors include mucin and inflammatory changes in the gallbladder, slow intestinal motility, increased intestinal absorption of cholesterol, and altered gut microbiota. Mechanisms of disease are linked with insulin resistance, obesity, the metabolic syndrome, and type 2 diabetes. The role of nuclear receptors, signaling pathways, gut microbiota, and epigenome are being actively investigated.

SUMMARY

Ongoing research on cholesterol gallstone disease is intensively investigating several pathogenic mechanisms, associated metabolic disorders, new therapeutic approaches, and novel strategies for primary prevention, including lifestyles.

Functions of the Gallbladder

The gallbladder stores and concentrates bile between meals. Gallbladder motor function is regulated by bile acids via the membrane bile acid receptor, TGR5, and by neurohormonal signals linked to digestion, for example, cholecystokinin and FGF15/19 intestinal hormones, which trigger gallbladder emptying and refilling, respectively. The cycle of gallbladder filling and emptying controls the flow of bile into the intestine and thereby the enterohepatic circulation of bile acids. The gallbladder also largely contributes to the regulation of bile composition by unique absorptive and secretory capacities. The gallbladder epithelium secretes bicarbonate and mucins, which both provide cytoprotection against bile acids. The reversal of fluid transport from absorption to secretion occurs together with bicarbonate secretion after feeding, predominantly in response to an adenosine 3',5'-cyclic monophosphate (cAMP)-dependent pathway triggered by neurohormonal factors, such as vasoactive intestinal peptide. Mucin secretion in the gallbladder is stimulated predominantly by calcium-dependent pathways that are activated by ATP present in bile, and bile acids. The gallbladder epithelium has the capacity to absorb cholesterol and provides a cholecystohepatic shunt pathway for bile acids. Changes in gallbladder motor function not only can contribute to gallstone disease, but also subserve protective functions in multiple pathological settings through the sequestration of bile acids and changes in the bile acid composition. Cholecystectomy increases the enterohepatic recirculation rates of bile acids leading to metabolic effects and an increased risk of nonalcoholic fatty liver disease, cirrhosis, and small-intestine carcinoid, independently of cholelithiasis. Among subjects with gallstones, cholecystectomy remains a priority in those at risk of gallbladder cancer, while others could benefit from gallbladder-preserving strategies. © 2016 American Physiological Society. Compr Physiol 6:1549-1577, 2016.

The systematic classification of gallbladder stones

Background

To develop a method for systematic classification of gallbladder stones, analyze the clinical characteristics of each type of stone and provide a theoretical basis for the study of the formation mechanism of different types of gallbladder stones.

Methodology

A total of 807 consecutive patients with gallbladder stones were enrolled and their gallstones were studied. The material composition of gallbladder stones was analyzed using Fourier Transform Infrared spectroscopy and the distribution and microstructure of material components was observed with Scanning Electron Microscopy. The composition and distribution of elements were analyzed by an X-ray energy spectrometer. Gallbladder stones were classified accordingly, and then, gender, age, medical history and BMI of patients with each type of stone were analyzed.

Principal Findings

Gallbladder stones were classified into 8 types and more than ten subtypes, including cholesterol stones (297), pigment stones (217), calcium carbonate stones (139), phosphate stones (12), calcium stearate stones (9), protein stones (3), cystine stones (1) and mixed stones (129). Mixed stones were those stones with two or more than two kinds of material components and the content of each component was similar. A total of 11 subtypes of mixed stones were found in this study. Patients with cholesterol stones were mainly female between the ages of 30 and 50, with higher BMI and shorter medical history than patients with pigment stones (P<0.05), however, patients with pigment, calcium carbonate, phosphate stones were mainly male between the ages of 40 and 60.

Conclusion

The systematic classification of gallbladder stones indicates that different types of stones have different characteristics in terms of the microstructure, elemental composition and distribution, providing an important basis for the mechanistic study of gallbladder stones.

Significantly increased risk of cardiovascular disease among patients with gallstone disease: a population-based cohort study

OBJECTIVE

To investigate whether gallstone disease (GD) increases the risk of developing cardiovascular disease (CVD) in a large population-based cohort.

METHODS

A study population including 6,981 patients with GD was identified from The Taiwan National Health Insurance Research Database between 2004 and 2005. GD patients were defined as patients with principal discharge diagnoses of cholelithiasis using the ICD-9-CM code 574. 27,924 patients without GD were randomly selected and matched for age and gender. All patients were followed for 6 years or until diagnosis for CVD. Cox proportional hazards regression model was used to assess the risk of developing CVD with adjustment for age, gender and co-morbid conditions.

RESULTS

During the six years follow-up period, 935 patients with GD and 2,758 patients without GD developed CVD. Patients with GD had an elevated risk of CVD (HR, 1.32; 95% CI, 1.22-1.43) when compared with those without GD. Similar relationship was observed when CVD was categorized i.e. stroke (HR, 1.15; 95% CI, 1.01-1.32), coronary heart disease (HR, 1.42; 95% CI, 1.28-1.58) and heart failure (HR, 1.31; 95% CI, 1.00-1.73). When GD was classified according to the level of severity, using patients without GD as reference, the risks of CVD were elevated in patients with non-severe GD (HR, 1.34; 95% CI, 1.24-1.46) as well as those with severe GD (HR, 1.20, 95% CI, 1.02-1.40), after adjusting for age, gender and comorbidities. In age-stratified analysis, patients aged 18-40 years with GD were at higher risk of developing CVD (HR, 1.42; 95% CI, 1.09-1.84) than older GD patients.

CONCLUSION

This study found an increased risk of CVD in patients diagnosed with GD. The excess risk was particularly high in younger GD patients. Prevention of GD could help reduce the risk of developing CVD, and the better effect could be achieved for the younger age groups.

A microstructural study of gallbladder stones using scanning electron microscopy

OBJECTIVE

The objective of this study was to describe the microstructure of different types of gallbladder stones to better understand the basis of gallbladder stone formation.

METHODS

Gallbladder stones from 387 patients with cholecystolithiasis were first analyzed by Fourier transform Infrared spectroscopy to identify the type of the gallbladder stone, and they were then examined using scanning electron microscopy to define their microstructure.

RESULTS

Cholesterol stones were mainly composed of plate-like or lamellar cholesterol crystals stacked tightly in a radial, cord-like, or irregular staggered arrangement. A small number of bilirubinate particles were seen occasionally. Pigment stones were mainly composed of loosely arranged bilirubinate particles with different shapes (sphere-like, clumping-like, or amorphous). Calcium carbonate stones were composed of calcium carbonate crystals having many shapes (bulbiform, ellipsoid, fagot-shaped, fusiform, hawthorn-shaped, cuboid, button-shaped, lamellar, broken firewood-shaped, rod-shaped, acicular, or crushed sugar cane-shaped). Bulbiform shaped crystals were the most common. Phosphate stones were mainly composed of different sized echin-sphere-like or rough bulbiform crystals. Bilirubinate particles were always adherent. Calcium stearate stones usually had a network structure with adherent bilirubinate particles. Protein stones usually had a honeycomb or chrysanthemum petal-like structure. Cystine stones were composed of hexagonal cystine crystals, some of which had prominent edges. Mixed stones presented different shapes according to their mixed components.

CONCLUSION

Different types of gallbladder stones had characteristic shapes and elements. This study provides an objective basis for further research regarding gallbladder stone formation.

Cholecystolithiasis is associated with Clonorchis sinensis infection

BACKGROUND

The objective of this study was to analyze gallbladder stones for direct evidence of a relationship between Clonorchis sinensis infection and gallbladder stones formation.

METHODOLOGY

We investigated one hundred eighty-three gallbladder stones for the presence of Clonorchis sinensis eggs using microscopy, and analyzed their composition using Fourier transform infrared spectroscopy. We confirmed the presence of Clonorchis sinensis eggs in the gallbladder stones using real-time fluorescent PCR and scanning electron microscopy.

PRINCIPAL FINDINGS

Clonorchis sinensis eggs were detected in 122 of 183 gallbladder stones based on morphologic characteristics and results from real-time fluorescent PCR. The proportion of pigment stones, cholesterol stones and mixed gallstones in the egg-positive stones was 79.5% (97/122), 3.3% (4/122) and 17.2% (21/122), respectively, while 29.5% (18/61), 31.1% (19/61) and 39.3% (24/61) in the egg-negative stones. The proportion of pigment stone in the Clonorchis sinensis egg-positive stones was higher than in egg-negative stones (P<0.0001). In the 30 egg-positive stones examined by scanning electron microscopy, dozens or even hundreds of Clonorchis sinensis eggs were visible (×400) showing a distinct morphology. Many eggs were wrapped with surrounding particles, and in some, muskmelon wrinkles was seen on the surface of the eggs. Also visible were pieces of texture shed from some of the eggs. Some eggs were depressed or without operculum while most eggs were adhered to or wrapped with amorphous particles or mucoid matter (×3000).

CONCLUSION

Clonorchis sinensis eggs were detected in the gallbladder stones which suggests an association between Clonorchis sinensis infection and gallbladder stones formation, especially pigment stones.

Tiny cystine stones in the gallbladder of a patient with cholecystolithiasis complicating acute cholecystitis: a case report

Cystine stones, the main component of which is cystine, are very common urinary calculi, but are rare in the gall bladder. In animals, there has been only one report of cystine gallstones in tree shrews, and to our knowledge, this is the first report of cystine gallstones in humans.

Pathophysiological significance of gallbladder volume changes in gallstone diseases

AIM: To study the pathophysiological significance of gallbladder volume (GBV) and ejection fraction changes in gallstone patients.

METHODS: The fasting GBV of gallstone patients with acute cholecystitis (n = 99), chronic cholecystitis (n = 85) and non-gallstone disease (n = 240) were measured by preoperative computed tomography. Direct saline injection measurements of GBV after cholecystectomy were also performed. The fasting and postprandial GBV of 65 patients with gallstones and chronic cholecystitis and 53 healthy subjects who received health examinations were measured by abdominal ultrasonography. Proper adjustments were made after the correction factors were calculated by comparing the preoperative and postoperative measurements. Pathological correlations between gallbladder changes in patients with acute calculous cholecystitis and the stages defined by the Tokyo International Consensus Meeting in 2007 were made. Unpaired Student’s t tests were used. P < 0.05 was deemed statistically significant.

RESULTS: The fasting GBV was larger in late stage than in early/second stage acute cholecystitis gallbladders (84.66 ± 26.32 cm³, n = 12, vs 53.19 ± 33.80 cm³, n = 87, P = 0.002). The fasting volume/ejection fraction of gallbladders in chronic cholecystitis were larger/lower than those of normal subjects (28.77 ± 15.00 cm³vs 6.77 ± 15.75 cm³, P < 0.0001)/(34.6% ± 10.6%, n = 65, vs 53.3% ± 24.9%, n = 53, P < 0.0001).

CONCLUSION: GBV increases as acute cholecystitis progresses to gangrene and/or empyema. Gallstone formation is associated with poorer contractility and larger volume in gallbladders that contain stones.

Coordinate regulation of gallbladder motor function in the gut-liver axis

Gallstones are one of the most common digestive diseases with an estimated prevalence of 10%-15% in adults living in the western world, where cholesterol-enriched gallstones represent 75%-80% of all gallstones. In cholesterol gallstone disease, the gallbladder becomes the target organ of a complex metabolic disease. Indeed, a fine coordinated hepatobiliary and gastrointestinal function, including gallbladder motility in the fasting and postprandial state, is of crucial importance to prevent crystallization and precipitation of excess cholesterol in gallbladder bile. Also, gallbladder itself plays a physiopathological role in biliary lipid absorption. Here, we present a comprehensive view on the regulation of gallbladder motor function by focusing on recent discoveries in animal and human studies, and we discuss the role of the gallbladder in the pathogenesis of gallstone formation.

Gallstone disease

Gallstone disease is one of the most prevalent gastrointestinal diseases with a substantial burden to health care systems that is supposed to increase in ageing populations at risk. Aetiology and pathogenesis of cholesterol gallstones still are not well defined, and strategies for prevention and efficient nonsurgical therapies are missing. This review summarizes current concepts on the pathogenesis of cholesterol gallstones with focus on the uptake and secretion of biliary lipids and special emphasis on recent studies into the genetic background.

Ursodeoxycholic acid exerts no beneficial effect in patients with symptomatic gallstones awaiting cholecystectomy

Ursodeoxycholic acid (UDCA) and impaired gallbladder motility purportedly reduce biliary pain and acute cholecystitis in patients with gallstones. However, the effect of UDCA in this setting has not been studied prospectively. This issue is important, as in several countries (including the Netherlands) scheduling problems result in long waiting periods for elective cholecystectomy. We conducted a randomized, double-blind, placebo-controlled trial on effects of UDCA in 177 highly symptomatic patients with gallstones scheduled for cholecystectomy. Patients were stratified for colic number in the preceding year (<3: 32 patients; > or =3: 145 patients). Baseline postprandial gallbladder motility was measured by ultrasound in 126 consenting patients. Twenty-three patients (26%) receiving UDCA and 29 (33%) receiving placebo remained colic-free during the waiting period (89 +/- 4; median [range]: 75[4-365] days) before cholecystectomy (P = .3). Number of colics, non-severe biliary pain, and analgesics intake were comparable. A low number of prior colics was associated with a higher likelihood of remaining colic-free (59% vs. 23%, P < .001), without effects on the risk of complications. In patients evaluated for gallbladder motility, 57% were weak and 43% were strong contractors (minimal gallbladder volume > respectively < or = 6 mL). Likelihood to remain colic-free was comparable in strong and weak contractors (31% vs. 33%). In weak contractors, UDCA decreased likelihood to remain colic-free (21% vs. 47%, P = .02). In the placebo group, 3 preoperative and 2 post-cholecystectomy complications occurred. In contrast, all 4 complications in the UDCA group occurred after cholecystectomy. In conclusion, UDCA does not reduce biliary symptoms in highly symptomatic patients. Early cholecystectomy is warranted in patients with symptomatic gallstones.

Gallbladder motility and gut hormone plasma levels in subjects with and without gallstones

Hormonal control of gallbladder motility is still unclear in patients with cholelithiasis. In a case-control study, we determined the characteristics of gallbladder emptying evaluated sonographically and the hormone levels of somatostatin, gastrin, and pancreatic polypeptide, before and after a fatty meal in 10 gallstone patients compared with 20 healthy subjects. Patients with lithiasis had a larger residual volume (median 12,0 ml vs 6,5 ml; P = 0.01) and a lower gallbladder ejection fraction (43% vs 70%, P = 0.02) than healthy subjects. During fasting, plasma pancreatic polypeptide concentrations were significantly higher in lithiasis patients (P < 0.03). In contrast, no differences between the two groups of patients were observed during the post prandial period. Somatostatin and gastrin plasma levels were similar in the two groups. Lastly, the serum bile salt levels were in the normal range and were not different between groups both during fasting and postprandial states. We conclude that large basal plasma concentrations of pancreatic polypeptide, a gut peptide inducing gallbladder relaxation, may constitute a factor facilitating lithogenesis.

Smooth muscle function and dysfunction in gallbladder disease

The gallbladder epithelium and smooth muscle layer are exposed to concentrated biliary solutes, including cholesterol and potentially toxic hydrophobic bile salts, which are able to influence muscle contraction. Physiologically, gallbladder tone is regulated by spontaneous muscle activity, hormones, and neurotransmitters released into the muscle from intrinsic neurons and extrinsic sympathetic nerves. Methods to explore gallbladder smooth muscle function in vitro include cholecystokinin (CCK) receptor-binding studies and contractility studies. In human and animal models, studies have focused on cellular and molecular events in health and disease, and in vitro findings mirror in vivo events. The interplay between contraction and relaxation of the gallbladder muscularis leads in vivo to appropriate gallbladder emptying and refilling during fasting and postprandially. Defective smooth muscle contractility and/or relaxation are found in cholesterol stone-containing gallbladders, featuring a type of gallbladder leiomyopathy; defects of CCKA receptors and signal transduction may coexist with abnormal responses to oxidative stress and inflammatory mediators. Abnormal smooth musculature contractility, impaired gallbladder motility, and increased stasis are key factors in the pathogenesis of cholesterol gallstones.

Measurements of gallbladder motor function by ultrasonography: towards standardization

As real-time ultrasonography is a cheap, noninvasive, relatively easy, validated and reproducible technique, it can be repeated over time to document time-related changes of gallbladder motor function. Ultimately, functional ultrasonography estimates gallbladder shape and volume in fasting state and in response to a test meal (liquid or mixed solid-liquid, provided there is sufficient fat content) or exogenous stimulus (e.g., i.v. cholecystokinin or ceruletide). Although functional ultrasonography of the gallbladder has been mainly used for research purposes in specific referral centres, its simplicity makes such a technique appealing in the clinical setting to assess gallbladder motor function in both health and disease. Indications include the study of healthy subjects and of patients during pathophysiologically relevant conditions; in particular when subjects are at risk for gallbladder stasis and gallstone disease or during gallstone disease when a decision concerning medical dissolution therapy is required.

Pathways of cholesterol crystallization in model bile and native bile

Hypersecretion of hepatic cholesterol, chronic supersaturation of bile with cholesterol and rapid precipitation of cholesterol crystals in the gallbladder from cholesterol-enriched vesicles represent the primum movens in cholesterol gallstone formation. Physical-chemical factors and pathways leading to cholesterol crystallization can be investigated in artificial model biles and ex vivo in fresh human bile. Depending on modulatory factors (i.e., lipid concentration, bile salt or phospholipid species, humidity, mucins, etc.), cholesterol can precipitate in several forms (i.e., monohydrate, anhydrous) and habits (i.e., plate-like, needle-like, intermediate arcs, filaments, tubules, spirals). Careful analysis of biliary cholesterol crystals includes biochemical analysis of precipitated crystals, polarizing quantitative light microscopy, and turbidimetric methods. In this paper, recent concepts on cholesterol crystallization in artificial model biles as well as in human bile will be reviewed.

Ultrasonographic assessment of gallbladder bile exchanges in healthy subjects and in gallstone patients

Impaired gallbladder motility may contribute to gallstone pathogenesis by providing time for nucleation and aggregation of cholesterol crystals. Simultaneous scintigraphic-ultrasonographic techniques have been proposed to assess alternating phases of gallbladder emptying and filling. To evaluate patterns of gallbladder motility and of postprandial bile flow by means of a single ultrasonographic technique, 12 healthy volunteers and 20 gallstone patients underwent minute-by-minute gallbladder ultrasonography for 3 h postprandially. Mathematical analysis of volume measurements was used to estimate hepatic and cholecystic bile flux through the gallbladder. Compared to controls, gallstone patients showed greater amounts of unexchanged cholecystic-to-hepatic bile (11% vs. 1%, p <.001) and most of them showed impaired gallbladder washout efficacy. Utrasonographic values of bile exchanges were similar to those derived from scintigraphic-sonographic studies in comparable groups of subjects. This study provides new ultrasonographic variables, which better express gallbladder bile retention in gallstone patients and strongly discriminate gallstone patients from controls.

An ultrasonographic evaluation of gallbladder emptying in patients with cholelithiasis

Impaired gallbladder emptying producing biliary stasis may provide potent carcinogen, which comes in contact with gallbladder mucosa for a prolonged period, inducing carcinogenesis. The aim was to study gallbladder emptying pattern in cholelithiasis. Postprandial gallbladder emptying was measured ultrasonographically in terms of fasting volume (FV), postprandial residual volume at 30 minutes (PP30), 60 minutes (PP60), and 90 minutes (PP90), residual fraction, and ejection volume (EV) in 58 patients with gallstones. Patients were divided into two groups of poor and good contractors on the basis of 50% maximal postprandial gallbladder emptying. Malonaldehyde level was estimated in 15 patients with cholelithiasis. Twenty-nine patients (50%) were poor contractors. The FV in patients with cholelithiasis (mean, 30.08 mL) was larger than the controls (mean, 17.55 mL) and the difference was statistically significant (p < 0.02). The FV in the cholelithiasis group correlated significantly with the PP30 (r = 0.85, p < 0.001), PP60 (r = 0.85, p < 0.001), PP90 (r = 0.78, p < 0.001), and EV (r = 0.65, p < 0.001). Ejection volume was significantly less in poor contractors (p <0.001). Residual fraction was significantly higher in poor contractors (p < 0.001). The biliary malonaldehyde in poor contractors (2.27 micromol/mL) was higher than in good contractors (1.78 micromol/mL), but the difference was statistically not significant. Significantly larger volumes of PP30, PP60, PP90, and residual fraction and a low EV indicate poor contraction leading to biliary stasis.

Review article: effect of bile salt pool composition on hepatic and biliary functions

The enterohepatic recirculation of bile salts exerts important regulatory effects on many hepatic, biliary and intestinal functions: such regulation is likely to depend, to a large extent, on the physical-chemical property of hydrophobicity of the recirculating pool. The present review summarizes the main experimental evidence carried out by our research group over the past two decades, in the attempt to investigate systematically the relationships between structural properties and biological effects of bile acids in humans. Hydrophobic bile acids (chenodeoxycholic acid, deoxycholic acid), but not hydrophilic acids (ursodeoxycholic acid), significantly suppressed hepatic activity of HMG-CoA reductase, the limiting step of cholesterol synthesis, and in vivo cholesterol 7alpha-hydroxylation, the limiting step of bile acid synthesis. The output of biliary cholesterol and phospholipid was also directly related to the hydrophobicity of the bile acid pool. Finally, treatment with chenodeoxycholic acid, but not with ursodeoxycholic acid, significantly decreased gall-bladder emptying rates. When turning to the in vitro model of HepG2 cells, hydrophobic bile acids were found to induce greater cytotoxic and pro-apoptotic effects. From this series of studies, we conclude that the regulatory effects of bile acids on the liver and biliary tract are largely dependent on the hydrophobic-hydrophilic balance of the recirculating bile acid pool.

Standards for diagnosis of gastrointestinal motility disorders. Section: ultrasonography. A position statement from the Gruppo Italiano di Studio Motilità Apparato Digerente

Ultrasonography is a non-invasive, relatively easy, validated and reproducible technique. We assessed the usefulness of functional ultrasonography to study disorders of gastro-oesophageal tract, gallbladder and pancreatic duct. Oesophagus Oesophagus and the gastro-oesophageal junction can be visualized in children up to 5 years old. Ultrasonography shows 100% sensitivity and 87.5% specificity compared to ambulatory pH-metry for gastro-oesophageal reflux disease diagnosis. Stomach Ultrasonography can be used to estimate whole gastric volume, antral area or diameters, antro-pyloric volume, transpyloric flow in fasting state and in response to test meal. Gallbladder Ultrasonography is reliable to estimate volume in fasting state and in response to test meal or exogenous stimulus. For both stomach and gallbladder, indications might include the study of healthy subjects and of pathophysiologically relevant conditions such as dysmotility-like dyspepsia, suspicion of delayed gastric emptying, diabetes mellitus, gallstone disease and effect of drugs either delaying or accelerating motility. Common bile duct Ultrasonography can be used to estimate interprandial and postprandial common bile duct diameter in patients with clinical suspicion of common bile duct obstruction in fasting state and in response to test meal or exogenous stimuli. Although functional ultrasonography is used mainly for research purposes, its simplicity makes it appealing for clinical use to assess gastrointestinal motility in health and disease.

Cholelithiasis induced in the Syrian hamster: evidence for an intramucinous nucleating process and down regulation of cholesterol 7 alpha-hydroxylase (CYP7) gene by medroxyprogesterone

This report reviews previously published studies from our laboratory and shows some recent morphological data obtained with scanning and transmission electron microscopy regarding gallstone formation and alteration of the gallbladder epithelium in the Syrian hamster model. Both male and female hamsters were treated with female sex steroids (estradiol alone, estradiol and medroxyprogesterone, medroxyprogesterone alone) during one month. The results show that the Syrian hamster is a good model to study bile changes, gallbladder structure changes, including gallstone formation, and the regulation of cholesterol metabolism at the molecular level. Arguments in favor of this animal model are presented and, during gallstone formation, epithelial cell changes, anionic mucus secretion, and formation of gallbladder luminal deposits can be demonstrated. Recent molecular biology observations related to the effect of female sex steroids on liver cholesterol 7 alpha-hydroxylase (CYP7) gene suggest that progestin alone or primed by estrogen down regulates CYP7 transcription and activity. In addition, progesterone in cell culture systems has been shown to enhance intracellular accumulation of free cholesterol by increasing its uptake and synthesis and by decreasing its esterification by inhibiting the activity of acylcoenzyme A: cholesterol acyltransferase. Non-esterified cholesterol is free to migrate to the extracellular spaces and may contribute to nucleation within the bile. It is suggested that these effects of progesterone on cholesterol metabolism combined with the CYP7 gene down regulation, physical changes in the mucus and the hypomotility of the gallbladder and biliary ducts result in hypersaturation of cholesterol in the bile which favors gallstone formation.