Dissolution of gallstones by methyl tert-butyl ether

Analytic Reviews : Nonsurgical Alternatives in the Management of Gallstones

Until recently, the only therapeutic option for patients with symptomatic gallstones was surgery. However, sev eral new and innovative nonsurgical approaches are cur rently available, including oral dissolution therapy with the bile salts, ursodeoxycholic and chenodeoxycholic acids, instillation of liquid solvents such as methyl tert- butyl ether directly into the gallbladder or the common bile duct, and extracorporeal shock-wave lithotripsy. We review the role of each of these methods in the management of patients with gallstones as well as the epidemiology, pathogenesis, natural history, and radi ological characteristics of gallstones, all important con siderations when choosing appropriate treatment for the individual patient.

High-avidity human IgG kappa monoclonal antibodies from a novel strain of minilocus transgenic mice

Human immunoglobulin transgenic mice provide a method of obtaining human monoclonal antibodies (Mabs) using conventional hybridoma technology. We describe a novel strain of human immunoglobulin transgenic mice and the use of this strain to generate multiple high-avidity human sequence IgG kappa Mabs directed against a human antigen. The light chain transgene is derived in part from a yeast artificial chromosome clone that includes nearly half of the germline human V kappa region. In addition, the heavy-chain transgene encodes both human mu and human gamma 1 constant regions, the latter of which is expressed via intratransgene class switching. We have used these animals to isolate human IgG kappa Mabs that are specific for the human T-cell marker CD4, have high binding avidities, and are immunosuppressive in vitro. The human Mab-secreting hybridomas display properties similar to those of wild-type mice including stability, growth, and secretion levels. Mabs with four distinct specificities were derived from a single transgenic mouse, consistent with an extensive diversity in the primary repertoire encoded by the transgenes.

Gallstone recurrence after direct contact dissolution with methyl tert-butyl ether

To determine the rate and characteristics of gallstone recurrence after direct contact dissolution with methyl tert-butyl ether, 60 consecutive patients were followed for up to 4.5 years (median 2.2 years) after complete disappearance of all stone residues and debris and cessation of adjuvant bile acid therapy. Initial gallstones had been multiple in all but four patients. Twenty-eight of the 60 patients developed recurrent gallstones. The cumulative risk of gallstone recurrence (actuarial analysis) was 23 +/- 6%, 34 +/- 7%, 55 +/- 8%, and 70 +/- 9% at one, two, three, and four years, respectively. The recurrent stones were usually multiple and small (6 +/- 4 mm). Gallstone recurrence was associated with recurrent biliary pain in two patients, one of whom developed acute cholecystitis. Recurrent stones were cleared completely by bile acid medication with or without shock-wave lithotripsy in 61 +/- 15% of patients at one year (actuarial analysis). In conclusion, gallstone recurrence after successful contact dissolution of multiple stones with methyl tert-butyl ether has to be expected in a high percentage of patients. Most patients, however, remain free of biliary pain during long-term follow-up.

Endoscopic management of bile duct stones

The surgical risk of common duct exploration for the treatment of biliary calculi is considerably higher than that of cholecystectomy. Therefore, introduction of endoscopic sphincterotomy in 1974 was a major advance. It has become the therapy of choice in cholecystectomized patients or in those with an increased operative risk. Endoscopic sphincterotomy has a mortality rate of around 1% and a morbidity rate of 7%. These figures compare favourably with open surgery, especially in old patients. The procedure fails in about 10% of all patients referred for endoscopic removal of their calculi. However, several techniques have been described or are currently under evaluation to overcome these failures: intracorporeal or extracorporeal lithotripsy, long-term stenting of the bile duct, or direct application of solvents. Long-term follow-up studies show that between 2% and 20% of successfully managed patients may develop recurrent stones, mainly caused by bile stasis and infection. Patients with a functioning gall-bladder and no concomitant gall-bladder stones probably do not require cholecystectomy after successful endoscopic treatment of their choledochal stones. While endoscopic stone removal has replaced surgery in the elderly frail patients it has no major advantages in the young and fit patients, especially when the gall-bladder is still in situ.

The donation and sale of blood by intravenous drug users

In spite of efforts to dissuade intravenous drug users (IVDUs) from donating or selling blood, some continue to do so. As part of a longitudinal study, 915 IVDUs in South Florida were interviewed concerning their history of donation or sale of blood and tested for antibodies to HIV-1 and HTLV-I/II. Approximately 17 percent had either donated or sold blood during 1985 through 1988; most contributors (80.4 percent) sold to commercial blood services. IVDUs who had donated/sold blood were more likely to be male and not in drug treatment than were those who had not contributed blood. IVDUs not in treatment at the time of interview were more likely than IVDUs in treatment to have sold blood. Of those who had donated/sold blood since 1985, 19.6 percent subsequently tested positive for antibodies to HIV-1 and 5.7 percent were positive for antibodies to HTLV-I/II. Increased effort is required to screen prospective donors and sellers, particularly at commercial blood banks.

In vitro comparison of different gall stone dissolution solvents

Extracorporeal shockwave lithotripsy (ESWL) of gall bladder stones leaves residual fragments that need to be dissolved by chemical solvents. In this study we compared the in vitro dissolving capacity of methyl tert-butyl ether (MTBE), mono-octanoin, limonene, and limonene/mono-octanoin (70%/30%). From nine sets of five human gall stones obtained at cholecystectomy, four stones were used for dissolution and the fifth was used for chemical analysis of cholesterol, calcium, and bilirubin contents. Eight sets were cholesterol stones with a mean (SD) cholesterol content of 89.9 (5.6)%. These stones dissolved completely in either solvent, often leaving sand-like debris, with the exception of one stone. MTBE dissolved cholesterol gall stones 100 times faster than mono-octanoin and 10 times faster than limonene or the limonene/mono-octanoin mixture (p less than 0.001). The combination of limonene and mono-octanoin was as effective as limonene alone. Of the four solvents, MTBE is the best one to evaluate for dissolution of residual fragments after ESWL treatment of gall bladder stones.

Experience with MTBE as a solvent for common bile duct stones in patients with T-tube in situ

The postcholecystectomy patients who have a T-tube in situ offer a convenient route through the T-tube to perfuse solvents into the common bile duct (CBD) for dissolving any retained common duct stones. If successful, this approach is much simpler and cheaper than the usual therapeutic modality used for CBD stones, namely, endoscopic papillotomy. Thus a most potent cholesterol solvent, methyl t-butyl ether (MTBE) was perfused through the T-tube into the CBD of five patients with retained common duct stones. The dose of the solvent varied, 1.5-5 mL 0.5-1 h, given 7-13 times amounting to a total of 20-66 mL. Instillation of MTBE in the T-tube was alternated with aspiration of the bile through T-tube. Only one patient showed complete disappearance of the bile duct stone following MTBE perfusion. Others did not show any appreciable response and had to be treated by endoscopic papillotomy (three patients) or mono-octanoin perfusion (one patient). Side-effects of MTBE perfusion included pain in the abdomen in all patients, somnolence and nausea/vertigo in two patients and the smell of ether on the breath in two patients. It is concluded that MTBE is not an effective agent for dissolution of retained CBD stones in patients with T-tube in situ.

Non-operative management of gallstones--a preliminary review

We describe our initial experience with extracorporeal shock-wave lithotripsy, direct solvent dissolution with methyl tert-butyl ether and mechanical extraction, in 17 symptomatic patients without significant gall-bladder wall disease using existing criteria for selection. Extracorporeal shock-wave lithotripsy and mechanical extraction are promising techniques. Methyl tert-butyl ether therapy has been fraught with difficulty.

Cholesterol gallstone disease: the current status of nonsurgical therapy

Gallstone disease is a common disease that appears to be related to a Western diet. The underlying pathogenesis is a subtle alteration in the liver such that excessive cholesterol is extracted from the liver cell by bile acids undergoing an enterohepatic recirculation. Gallstone disease progresses through well-defined stages, beginning with a bile supersaturated with cholesterol and proceeding to crystal formation, stone growth, and finally symptoms caused by impaction of a stone in either the cystic duct or the common bile duct. The natural history is that most stones never cause symptoms. Stones that cause symptoms have been present for an average of 12 years. The treatment of truly asymptomatic stones should be observation. Ultrasonography of the right upper quadrant is the gold standard for the diagnosis of stones in the gallbladder. Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for the diagnosis of stones in the common bile duct. Oral cholecystogram (OCG) helps select patients who have noncalcified, floating stones that may be dissolved with bile acids or methyl tertiary butyl ether (MTBE). Therapy with chenodiol has been a disappointment because of a low complete response rate. The ideal candidate for attempted dissolution with chenodiol would be a thin woman with hypercholesterolemia and a small number of symptomatic, small, floating, radiolucent gallstones. Ursodeoxycholic acid (Urso), when it is available, will have all of the attributes of chenodiol and virtually none of the side effects. Rapid dissolution of gallstones with MTBE shows great promise of being a generally available means of dissolving gallstones. Extracorporeal shock wave lithotripsy also shows promise, but its general availability may be limited by the cost of the equipment needed. As of now, the treatment of choice for symptomatic gallstones remains cholecystectomy, unless there is a compelling reason not to operate.

Combined treatment of stone-obstructed hepatico-jejunostomy with interventional techniques and ESWL

In a 37-year-old woman with recurrent stenosis of a biliary digestive tract anastomosis and subsequent formation of bile stones, current methods of percutaneous management were useful in dilating the stenotic areas but could not remove a single bile stone within the left hepatic duct. It was successfully treated by using extracorporeal shock wave lithotripsy (ESWL) without major side effects.

Methyl tert-butyl ether fails to dissolve retained radiolucent common bile duct stones

Methyl tert-butyl ether (MTBE) has been recently proposed as a new therapeutic modality for the dissolution of cholesterol gallstones. To further evaluate efficacy and tolerability of this new litholytic agent, we have administered MTBE to 3 patients with nonobstructive radiolucent common bile duct stones after recent surgery. Methyl tert-butyl ether (8-11 ml/day) was infused after aspiration of bile via a Teflon catheter inserted through the postoperative T tube. Gentle aspiration and reinfusion were performed continuously to generate stirring. The total amount of MTBE retrieved during the entire procedure was equivalent to approximately 30% of the volume infused. In all cases, MTBE failed to dissolve the radiolucent stones, which were then dissolved with continuous infusion of monooctanoin via the biliary catheter. The characteristic odor of MTBE was detected on the breath of the patients, and nausea and somnolence developed during the treatment. Serum hepatic and pancreatic enzymes did not change after MTBE. In the third subject, who received 11 ml/day of MTBE for 2 consecutive days (total of 22 ml), histologic evidence of duodenitis was found around the papilla. In our opinion, the lack of efficacy of MTBE in dissolving retained radiolucent common bile duct stones was mainly related to its leakage from the common bile duct into the duodenum and the ensuing local chemical toxicity and systemic absorption. As MTBE needs a persistent stone-solvent contact to exert its litholytic action and, at the same time, its toxicity prevents the infusion of larger doses, MTBE use should be restricted to stones placed in closed chambers, such as the gallbladder.

Fragmentation of gallstones by extracorporeal shock waves

We treated nine patients with functioning gallbladders containing one to three symptomatic radiolucent stones not larger than 25 mm in diameter, as well as five patients with stones in the common bile duct that were not removable by endoscopic procedures, by means of extracorporeally generated shock waves during general anesthesia. The patients with gallbladder stones received adjuvant treatment with a combination of ursodeoxycholic acid and chenodeoxycholic acid. All gallbladder stones were disintegrated into sludge or fragments with diameters of no more than 8 mm. In six of the nine patients the fragments disappeared completely within 1 to 25 weeks. No adverse effects were detected during a follow-up period of 10 to 34 weeks, except transient biliary pain in two patients, with mild pancreatitis in one. In four of the five patients with common-bile-duct stones, shock-wave treatment permitted stone disintegration and successful endoscopic extraction or spontaneous passage of fragments. We conclude that gallstone disease may be treated successfully and without serious adverse effects by extracorporeally generated shock waves in selected patients.