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

A computer study of the risk of cholesterol gallstone associated with obesity and normal weight

Obese people differ from the people of normal weight in gall bladder motility and have a higher risk of cholesterol stone formation. In this study, using a mathematical model of cholesterol homeostasis, which also considers the enterohepatic circulation of bile as well as cholesterol, we investigated the risk of cholesterol stone formation in obese and normal-weight groups who had normal blood cholesterol levels. We associated the risk of stone formation with the amount of cholesterol released into bile and the amount of de novo-synthesized cholic acid. For both groups, we determined the conditions of low and high risk. In addition, we analyzed the potential effects of changes in gall bladder motility with increased weight. The results showed that the obese group exhibited increased kinetics of enterohepatic circulation, leading to a significant increase in blood cholesterol levels, which can be reduced by increasing the amount of cholesterol in bile. Based on this finding, we suggest that for obese people, it is beneficial to reduce the amount and change the composition of circulating bile through the inhibition of cholic acid synthesis along with cholesterol synthesis. Furthermore, obese people should maintain a triglyceride-lowering diet and consume small meals containing fat, preferably in combination with agents that can reduce bile output from the gall bladder.

Gallbladder function and dynamics of bile flow in asymptomatic gallstone disease

AIM: To investigate the effects of gallbladder stones on motor functions of the gallbladder and the dynamics of bile flow in asymptomatic gallstone disease.

METHODS: Quantitative hepatobiliary scintigraphy was performed to detect the parameters of gallbladder motor function [gallbladder ejection fraction (GBEF), gallbladder visualization time (GBVT), gallbladder time to peak activity (GBT_max), gallbladder half emptying time (GBT_1/2), and transit time of bile to duodenum (TTBD)] in 24 patients with asymptomatic cholelithiasis who were diagnosed incidentally during routine abdominal ultrasonographic examination and 20 healthy subjects with normal gallbladder.

RESULTS: Even though there was no significant difference in the clinical and laboratory parameters between the patient and control groups, all parameters of gallbladder function except TTBD were found to differ significantly between the two groups. GBEF in the patient group was decreased (P = 0.000) and GBVT, GBT_max, GBT_1/2 in the patient group were longer (P = 0.000, P = 0.015, P = 0.001, respectively).

CONCLUSION: Our results showed that even if there were not any clinical and laboratory findings, gallbladder filling and emptying could be impaired in patients with gallstone disease.

Short-term ursodeoxycholic acid treatment improves gallbladder bile turnover in gallstone patients: a randomized trial

Ursodeoxycholic acid (UDCA) prevents in vitro gallbladder (GB) muscle damage caused by acute cholecystitis and reduces risk of biliary pain and complications in gallstone (GS) patients. These effects could be partially explained by the improved GB bile turnover.

OBJECTIVES

To assess the effect of short-term UDCA treatment on GB motility and bile turnover.

METHODS

Ultrasonographic (US) assessment of GB volumes was performed in 16 GS patients, in the postprandial phase, for 90 min with a time sampling of 1 min, before and after 30 days of UDCA (10 mg kg(-1) die(-1)) or placebo, randomly assigned. US data were analysed with statistical tools and with computer fluido-dynamic (CFD) software Fluent(TM) to simulate GB bile flow.

RESULTS

After therapy, fasting volume (FV) increased from 21.6 +/- 9 to 28.2 +/- 12 mL (p < 0.001) while the ejection fraction (EF) remained unchanged (44.5 +/- 17% vs 45.1 +/- 20%; p: ns). Volumes before and after treatment were poorly correlated (0.02 < r < 0.35), unlike those in placebo patients (r > 0.6). The average GB volume was increased in 7 out of 10 patients following UDCA (range 7-67%). CFD analysis supports the finding of improved bile flow after treatment.

CONCLUSIONS

Unlike results of conventional US parameters of GB motility, CFD analysis shows that UDCA improves GB bile turnover in GS patients.

The gall of subordination: changes in gall bladder function associated with social stress

Diverse physiological and behavioural mechanisms allow animals to effectively deal with stressors, but chronic activation of the stress axis can have severe consequences. We explored the effects of chronic social stress on agonistic behaviour and gall bladder function, a critical but widely neglected component of stress-induced gastrointestinal dysfunction. Prolonged cohabitation with dominant individuals elicited behavioural modifications and dramatically increased bile retention in subordinate convict cichlid fish (Archocentrus nigrofasciatum). The key predictor of gall bladder hypertrophy was social subordination rather than status-related differences in food intake or body size. Stress-induced inhibition of gall bladder emptying could affect energy assimilation such that subordinate animals would not be able to effectively convert energy-rich food into mass gain. These results parallel changes in gall bladder function preceding cholesterol gallstone formation in humans and other mammals. Thus, social stress may be an important diagnostic criterion in understanding pathologies associated with gall bladder dysfunction.

Ultrasonography in the assessment of gallbladder motor activity

Ultrasonography is an accurate and useful method for studying gallbladder volume variations and thus indirectly gallbladder emptying and refilling in humans. It has been shown that gallbladder main motor function is the result of a bellows-like mechanism with outflow and inflow of bile occurring during continuously alternating phases of gallbladder emptying and filling, that in turn lead to bile recycling within the gallbladder. Therefore, bile flux through the gallbladder cannot be properly expressed by time and rate of gallbladder emptying and gallbladder ejection fraction. In an attempt to analyse the gallbladder volume-hepatic bile flux relationship, simultaneous assessment of the gallbladder volume variations at ultrasonography and of the labelled bile in the gallbladder at cholescintigraphy during continuous infusion of an hydroxy iminodiacetic acid compound has been carried out. By applying a mathematical model to the analysis of gallbladder volume ultrasonography measurements, it is possible to measure the flux of bile through the gallbladder. By validating ultrasonography assessment of gallbladder volume variations with quantitative cholescintigraphy, it has been shown that the single non-invasive ultrasonography technique with serial frequent measurements of the gallbladder volume enables separate estimation of the flux of bile through the gallbladder in humans and in physiological conditions. In the postprandial state, hepatic bile was mainly: (1) stored in the gallbladder in a first phase; (2) emptied from the gallbladder in a second phase; and (3) stored in the gallbladder in a third phase. The amount of bile flowing bidirectionally through the cystic duct was about fivefold greater than that estimated with the usually employed variables, such as gallbladder ejection fraction or emptying and refilling delta volume. The mathematical analysis of minute-by-minute ultrasonography measurements of gallbladder volume variations yields both physiological and pathological insights. In healthy volunteers, it has been shown that: (1) caloric content of meals affects the total amount of bile recycled by the gallbladder; and (2) fat content of meals affects the modality of gallbladder emptying and refilling but does not affect the total amount of bile recycled by the gallbladder. In gallstone patients, a decreased turnover of bile has been shown which may contribute to cholesterol crystal precipitation and stone growth. In conclusion, unlike conventional variables used to assess gallbladder motor function such as gallbladder ejection fraction and rate of gallbladder emptying, mathematical analysis of frequent ultrasonography measurements of gallbladder volume variations enables non-invasive estimation of bile flow through the gallbladder in normal and abnormal physiological conditions.