Gallstone dissolution

Gallstones

Gallstone disease is a worldwide medical problem, but the incidence rates show substantial geographical variation, with the lowest rates reported in African populations. Publications in English language on gallstones which were obtained from reprint requests and PubMed database formed the basis for this paper. Data extracted from these sources included authors, country, year of publication, age and sex of patients, pathogenesis, risk factors for development of gallstones, racial distribution, presenting symptoms, complications and treatment. Gallstones occur worldwide, however it is commonest among North American Indians and Hispanics but low in Asian and African populations. High biliary protein and lipid concentrations are risk factors for the formation of gallstones, while gallbladder sludge is thought to be the usual precursor of gallstones. Biliary calcium concentration plays a part in bilirubin precipitation and gallstone calcification. Treatment of gallstones should be reserved for those with symptomatic disease, while prophylactic cholecystectomy is recommended for specific groups like children, those with sickle cell disease and those undergoing weight-loss surgical treatments. Treatment should be undertaken for a little percentage of patients with gallstones, as majority of those who harbor them never develop symptoms. The group that should undergo cholecystectomy include those with symptomatic gallstones, sickle cell disease patients with gall stones, and patients with morbid obesity who are undergoing laparotomy for other reasons.

Intestinal bile acid physiology and pathophysiology

Bile acids (BAs) have a long established role in fat digestion in the intestine by acting as tensioactives, due to their amphipathic characteristics. BAs are reabsorbed very efficiently by the intestinal epithelium and recycled back to the liver via transport mechanisms that have been largely elucidated. The transport and synthesis of BAs are tightly regulated in part by specific plasma membrane receptors and nuclear receptors. In addition to their primary effect, BAs have been claimed to play a role in gastrointestinal cancer, intestinal inflammation and intestinal ionic transport. BAs are not equivalent in any of these biological activities, and structural requirements have been generally identified. In particular, some BAs may be useful for cancer chemoprevention and perhaps in inflammatory bowel disease, although further research is necessary in this field. This review covers the most recent developments in these aspects of BA intestinal biology.

Percutaneous transhepatic endoscopic electrohydraulic lithotripsy of biliary tract calculi after orthotopic liver transplantation

The development of biliary tract calculi after orthotopic liver transplantation presents a unique clinical problem. Previously described techniques for removing biliary stones by shock wave lithotripsy, litholytic therapy with oral bile acids, and endoscopic mechanical extraction may be ineffective or contraindicated in liver transplant patients. For this reason, percutaneous transhepatic electrohydraulic lithotripsy (EHL) was performed using an 11 French flexible ureteroscope in two pediatric patients who developed biliary tract calculi following orthotopic liver transplant. There were no complications and postoperative follow-up over 4 years has been uneventful. To our knowledge, these represent the first reported cases of percutaneous transhepatic endoscopic EHL to fragment biliary tract stones in a transplanted liver, which for us has been a safe and effective therapeutic option.

Taurodeoxycholate activates potassium and chloride conductances via an IP3-mediated release of calcium from intracellular stores in a colonic cell line (T84)

Whole-cell patch-clamp techniques and fluorescence measurements of intracellular Ca2+ concentration, (Ca2+)i, were used to investigate the mechanism of taurodeoxycholate (TDC) stimulation of Cl- secretion in the T84 colonic cell line. During perforated whole-cell recordings, the cell membrane voltage was alternately clamped to EK and ECl. Initially, TDC (0.75 mM) stimulated inward nonselective cation currents that were composed of discrete large conductance single-channel events. This initial response was followed by activation of K+ and Cl- currents with peak values of 385 +/- 41 pA and 98 +/- 28 pA, respectively (n = 12). The K+ and Cl- currents oscillated while TDC was present and returned to baseline levels upon its removal. The threshold for activation of the oscillatory currents was 0.1 mM TDC. Taurocholate, a bile acid that does not stimulate colonic Cl- secretion, induced no current response. The TDC-induced currents could be activated in Ca(2+)-free bathing solutions. Preincubation of cells with the Ca2+ chelator, bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, tetra(acetoxymethy)-ester (20 microM), (BAPTA-AM), eliminated the K+ and Cl- current responses, although the nonselective cation channel events were still present. Replacement of bath Na+ with NMDG+ inhibited the TDC-induced nonselective cation current but did not affect the K+ or Cl- currents. TDC induced a transient (Ca2+)i rise of 575 +/- 70 nM from a baseline of 71 +/- 5 nM (n = 15); thereafter, (Ca2+)i either plateaued or oscillated. TDC-induced (Ca2+)i oscillations were observed in the absence of bath Ca2+; however, removal of bath Ca2+ during the TDC response caused (Ca2+)i to return to near baseline values. Simultaneous K+ current and (Ca2+)i measurements confirmed that the initial nonselective cation current was independent of (Ca2+)i, while K+ current oscillations were in phase with the (Ca2+)i oscillations. TDC induced inositol monophosphate (IP) accumulation, reflecting production of inositol 1,4,5-trisphosphate (IP3) during TDC stimulation. The response to TDC during standard whole-cell patch-clamp was similar to that observed with perforated whole-cell recordings, except the nonselective cation current was prolonged. When heparin (1 mg/ml) was added to the pipette under these conditions, the Ca(2+)-activated currents were inhibited, but the nonselective cation currents were unaffected. These data suggest that TDC induces a Ca(2+)-independent nonselective cation conductance, perhaps by directly permeabilizing the plasma membrane. TDC stimulates Cl- secretion by activating K+ and Cl- conductances via an IP3-mediated release of Ca2+ from intracellular stores.