The pathogenesis of cholesterol gallstones a review

Direct observation of cholesterol monohydrate crystallization

Cholesterol crystallization is integral to the pathology of diseases such as atherosclerosis and gallstones, yet the relevant mechanisms of crystal growth have remained elusive. Here, we use a variety of in situ techniques to examine cholesterol monohydrate crystallization over multiple length scales. In this study, we first identified a biomimetic solvent to generate triclinic monohydrate crystals, while avoiding the formation of nonphysiological solvates and enabling crystallization at rates where the dynamics of surface growth could be captured in real time. Using a binary mixture of water and isopropanol, with the latter serving as a surrogate for lipids in physiological environments, we show that cholesterol monohydrate crystals grow classically by the nucleation and spreading of crystal layers. Time-resolved imaging confirms that layers are generated by dislocations and monomers incorporate into advancing steps after diffusion along the crystal surface and not directly from the solution. In situ atomic force microscopy (AFM) and microfluidics measurements concertedly reveal abundant macrosteps, which engender a self-inhibition mechanism that reduces the rate of crystal growth. This finding stands in contrast to numerous other systems, in which classical mechanisms lead to unhindered growth by spreading of single layers.

Gallstone Ileus: Clinical Presentation and Radiological Diagnosis

The term "gallstone ileus" refers to intestinal obstruction brought on by a gallstone lodged within its lumen. The gallstone travels through a fistula that develops because of the constant pressure it exerts on the gall bladder. The symptoms are vague and confounding which can commonly lead to delay in diagnosis. The preferred imaging technique is a computed tomography scan. The diagnosis is confirmed by the identification of Rigler's Triad on a CT scan, which includes a small intestinal obstruction, pneumobilia, and an ectopic stone in the intestine. The condition is associated with several complications and needs to be treated with emergency surgery. This case demonstrates how a patient could have non-specific symptoms and how early detection by imaging was crucial to the patient's treatment.

The underlying mechanisms: how hypothyroidism affects the formation of common bile duct stones-a review

For decades, one well-known risk factor for the development of gallbladder stones has been hypothyroidism. Recent studies have interestingly reported that the risk in particular for common bile duct (CBD) stones increases in clinical and subclinical hypothyroidism. There are multiple factors that may contribute to the formation and/or accumulation of CBD stones in hypothyroid patients, including decreased liver cholesterol metabolism, diminished bile secretion, and reduced sphincter of Oddi relaxation. This paper focuses on the mechanisms possibly underlying the association between hypothyroidism and CBD stones. The authors conclude that when treating patients with CBD stones or microlithiasis, clinicians should be aware of the possible hypothyroid background.

Measuring the rate of weight gain and the influential role of diet in patients undergoing elective laparoscopic cholecystectomy: a 6-month follow-up study

Weight gain after cholecystectomy is one of the major surgical problems consistent with morbidities and long-term mortalities. Here, we aimed to study the impact of palliative cholecystectomy on weight gain and nutritional status of the patients before and in 1, 4 and 6 months after surgery. We performed a prospective survey on a cohort of 48 patients undergoing elective cholecystectomy. The nutritional status of the patients was collected by nutrition nurse and analysed by NutriBase software. There were 13 (16%) females and 35 (84%) males with the mean age of 51.8 ± 1.97. In 6 months after surgery, patients had higher values of BMI, daily energy expenditure, carbohydrate and lipid consumption and a decreased level of protein consumption. Weight gain after surgery was caused by an increase in fat consumption which resulted in the weight gain and worsening of lipid profile. Dietary consultation, shortly after surgery, would improve patient outcome after cholecystectomy.

Combined interaction of phospholipase C and apolipoprotein A-I with small unilamellar lecithin-cholesterol vesicles: influence of apolipoprotein A-I concentration and vesicle composition

We report the combined effects of phospholipase C (PLC), a pronucleating factor, and apolipoprotein A-I (apo A-I), an antinucleating factor, in solutions of model bile. Results indicate that apo A-I inhibits cholesterol nucleation from unilamellar lecithin vesicles by two mechanisms. Initially, inhibition is achieved by apo A-I shielding of hydrophobic diacylglycerol (DAG) moieties so as to prevent vesicle aggregation. Protection via shielding is temporary. It is lost when the DAG/apo A-I molar ratio exceeds a critical value. Subsequently, apo A-I forms small ( approximately 5-15 nm) complexes with lecithin and cholesterol that coexist with lipid-stabilized (400-800 nm) DAG oil droplets. This microstructural transition from vesicles to complexes avoids nucleation of cholesterol crystals and is a newly discovered mechanism by which apo A-I serves as an antinucleating agent in bile. The critical value at which a microstructural transition occurs depends on binding of apo A-I and so varies with the cholesterol mole fraction of vesicles. Aggregation of small, unilamellar, egg lecithin vesicles (SUVs) with varying cholesterol composition (0-60 mol %) was monitored for a range of apo A-I concentrations (2 to 89 microg/mL). Suppression of aggregation persists so long as the DAG-to-bound-apo A-I molar ratio is less than 100. A fluorescence assay involving dansylated lecithin shows that the suppression is an indirect effect of apo A-I rather than a direct inhibition of PLC enzyme activity. The DAG-to-total apo A-I molar ratio at which suppression is lost increases with cholesterol because of differences in apo A-I binding. Above this value, a microstructural transition to DAG droplets and lecithin/cholesterol A-I complexes occurs, as evidenced by sudden increases in turbidity and size and enhancement of Forster resonance energy transfer; structures are confirmed by cryo TEM.

Effect of beta-sitosterol on precipitation of cholesterol from non-aqueous and aqueous solutions

The aim of the present work was to study the solubility and phase behaviour of the beta-sitosterol-cholesterol mixed crystals in the presence and absence of water. Cholesterol, beta-sitosterol and 3:1, 1:1 and 1:3 mixtures of these were co-precipitated from acetone and acetone-water solutions. Precipitated crystals were analysed using powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), optical microscopy and Karl-Fischer titrimetry. The quantification of the sterols in solutions was preformed using GC-MS. The solubility of the sterols was mutually limiting. In the aqueous system, the solubility of both the sterols were significantly lower than in the absence of water, but the decrease in the solubility was considerably greater with the more hydrophobic beta-sitosterol. In the aqueous system, the total sterol solubility decreased with the increasing proportion of beta-sitosterol. The formation of new crystal structures, solid solutions of cholesterol and beta-sitosterol, was observed in non-aqueous as well as in aqueous environments except with the lowest cholesterol proportion in the system, in which case mixed crystals with eutectic behaviour were formed.