Endoscopic palliation of malignant gastric outlet obstruction using self-expandable metallic stents: results of a multicenter study

BACKGROUND AND STUDY AIMS

Gastric outlet obstruction is a late event in the natural history of biliopancreatic tumours. Metallic self-expanding stents inserted under endoscopic and fluoroscopic guidance can be used for palliation. The aim of this study was to evaluate the feasibility, efficacy, and complications of endoscopic duodenal stenting in patients with malignant gastric outlet obstruction.

PATIENTS AND METHODS

Between August 1998 and November 2001, 63 patients (31 women, 32 men; mean age 73 +/- 12) presenting with clinical symptoms of duodenal obstruction underwent endoscopic stenting with large metallic prostheses. Complications and clinical outcome were assessed both retrospectively and prospectively.

RESULTS

Of the patients, 58 needed one duodenal stent and two overlapping stents were required in five patients. Stenting was immediately successful in 60/63 patients (95%). At the time of the duodenal procedure, 25 previously inserted biliary stents were still patent; biliary stenting was attempted during the same procedure in 18 patients; and 20 patients had no biliary stricture. There was no procedure-related mortality. There were complications in 30 % of patients: 13 stent obstructions, 4 stent migrations and 2 duodenal perforations (treated surgically). For 44 patients (70%) there were no minor or major digestive problem during their remaining lifetime. An exclusively peroral diet was possible in 58 patients (92%), but was considered satisfactory (solid or soft) in 46/63 patients (73%). Of the patients, 53 (84 %) died between 1 and 64 weeks after the duodenal stenting (median survival 7 weeks).

CONCLUSIONS

Endoscopic stenting for the palliation of malignant gastric outlet obstruction is feasible and well-tolerated in most patients. Most dysfunctions can be managed endoscopically.

[Radiation-induced stricture of the papilla and the common bile duct: successful treatment with balloon dilation]

Radiation-induced lesions of the bile ducts rarely occur and may be difficult to manage. We report the case of a 59-year old woman who developed radiation-induced stenosis of the papilla and the common bile duct 25 years after abdominal radiation therapy for abdominal non-Hodgkin's lymphoma. She presented with recurrent cholangitis and chronic cholestasis. Endoscopic results showed dilation of the intrahepatic bile ducts, radiation-induced inflammation and narrowing of the antrum and the duodenum, and stricture of the papilla and the last few millimeters of the common bile duct. The patient was treated with endoscopic balloon dilation. Forty-two months after endoscopic dilation, the patient remained asymptomatic with normal liver tests and no biliary dilation at ultrasound.

Regulation of ClC-2 chloride channels in T84 cells by TGF-α

The almost ubiquitously expressed ClC-2 chloride channel is activated by hyperpolarization and osmotic cell swelling. Osmotic swelling also activates a different class of outwardly rectifying chloride channels, and several reports point to a link between protein tyrosine phosphorylation and activation of these channels. This study examines the possibility that transforming growth factor-α (TGF-α) modulates ClC-2 activity in human colonic epithelial (T84) cells. TGF-α (0.17 nM) irreversibly inhibited ClC-2 current in nystatin-perforated whole cell patch-clamp experiments, whereas a superimposed reversible activation of the current was observed at 8.3 nM TGF-α. Both effects required activation of the intrinsic epidermal growth factor receptor (EGFR) tyrosine kinase activity, of phosphoinositide 3-kinase, and of protein kinase C. With microspectrofluorimetry of the pH-sensitive fluorescent dye 2′,7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein, TGF-α was shown to reversibly alkalinize T84 cells at 8.3 nM but not at 0.17 nM, suggesting that 8.3 nM TGF-α-induced alkalinization activates ClC-2 current. This study indicates that ClC-2 channels are targets for EGFR signaling in epithelial cells.

Observation of a metastable periodic structure for the (001) surface of KTaO3 after cleaving in situ

Helium atom diffraction experiments carried out under ultrahigh vacuum conditions on a freshly cleaved (001) surface of KTaO3 reveal metastable features which decay over a period of several hours. The initial He diffraction pattern contains large scattering intensity satellite peaks very close to the specular reflection beam. As time from cleaving elapses, the satellite intensities diminish virtually to zero while the specular intensity increases, and the diffraction pattern evolves into one consistent with the (1x1) bulk termination surface. The data are compared with model calculations for scattering from a series of terraces at two heights with a distribution of terrace lengths [Surf. Sci. 384, 15 (1997)].

Two mild cystic fibrosis-associated mutations result in severe cystic fibrosis when combined in cis and reveal a residue important for cystic fibrosis transmembrane conductance regulator processing and function

The number of complex cystic fibrosis transmembrane conductance regulator (CFTR) genotypes identified as having double-mutant alleles with two mutations inherited in cis has been growing. We investigated the structure-function relationships of a severe cystic fibrosis (CF)-associated double mutant (R347H-D979A) to evaluate the contribution of each mild mutation to the phenotype. CFTR mutants expressed in HeLa cells were analyzed for protein biosynthesis and Cl(-) channel activity. Our data show that R347H is associated with mild defective Cl(-) channel activity and that the D979A defect leads to misprocessing. The mutant R347H-D979A combines both defects for a dramatic decrease in Cl(-) current. To decipher the molecular mechanism of this phenotype, single and double mutants with different charge combinations at residues 347 and 979 were constructed as charged residues were involved in this complex genotype. These studies revealed that residue 979, located in the third cytoplasmic loop, is critical for CFTR processing and Cl(-) channel activity highlighting the role of charged residues. These results have also important implications for CF, as they show that two mutations in cis can act in concert to alter dramatically CFTR function contributing to the wide phenotypic variability of CF disease.

[Late biliary complications after endoscopic sphincterotomy for common bile duct stones in patients older than 65 years of age with gallbladder in situ]

The aim of this retrospective study was to evaluate the nature and the frequency of biliary complications after endoscopic retrograde cholangiography for common bile duct stones in elderly patients with gallbladder in situ.

METHODS

Between 1991 and 1993, 169 consecutive patients with gallbladder in situ, older than 65 years (79 +/- 8) had an endoscopic retrograde cholangiography with sphincterotomy for choledocholithiasis. Information on the early (<1 month) and late biliary complications, treatment and mortality were obtained by mail or phone calls from patients and general practitioners. Long-term data were obtained for 139 patients (82%). Mean follow-up was 56.5 months (80 months for patients still alive at the end of the study).

RESULTS

Early complications occurred in 13 patients (10.8%). Seven patients had acute cholecystitis, present before the procedure in all cases; all were treated by surgery. Other early complications included cholangitis (n =7), mild acute pancreatitis (n =3), bleeding (n =1), perforation (n =1), biliary colic (n =1), pneumopathy (n =1) and bradycardia (n =1), all treated medically. Forty patients underwent early cholecystectomy, and 5 died during the first month without biliary disease. Late complications were thus assessed in 94 patients and occurred in 13 (14%), i.e around 2% per year. Complications were acute cholangitis (n=4), biliary pain (n =4), cholecystitis (n =2), abdominal pain (n =2) and jaundice due to sphincterotomy stenosis (n =1). Five patients had cholecystectomy, 1 a radiological drainage and 7 were treated medically. No death due to a biliary complication was observed. The presence of gallstones, the absence of gallbladder opacification at cholangiography were not prognostic factors for the recurrence of biliary symptoms. 65 patients (50%) died without biliary disease during the follow-up (actuarial death rate 10.5% per year).

CONCLUSION

Late biliary complications after endoscopic retrograde cholangiography for choledocholithiasis in patients with gallbladder in situ are rare (2% per year). Prophylactic cholecystectomy after sphincterotomy does not seem warranted in elderly patients, because of rare recurrent biliary symptoms, low mortality rate, and limited life expectancy.

Phosphine sampling and analysis using silver nitrate impregnated filters

In the field of industrial hygiene, besides the necessity of monitoring phosphine with direct reading apparatus to prevent accidents, there is a need for a method of sampling and analysing phosphine to control workers' exposure. The use of filters impregnated with silver nitrate to collect arsine, phosphine and stibine in workplace air has been described in the literature. Having previously chosen this type of filter to collect arsine, we studied its characteristics for phosphine capture. A filter impregnated with sodium carbonate was used both as a prefilter to collect the particles and to trap arsenic trioxide. After dissolving the silver compounds in nitric acid, ICP emission spectrometry was used to carry out the analysis. This article describes the comparative sampling we performed in a microelectronic laboratory and in a fumigation chamber (130 samples) to determine the concentration of AgNO3 impregnation solution to be used, the detection limit of the method and the retention capacity of the impregnated filters. Interference with other gases reacting with silver nitrate was studied and the storage time for sampled filters and analysis solutions was checked. The detection limit of the adopted method is better than 1 microg per filter, and the retention capacity exceeds 300 microg per filter. The problem of how to sample phosphine when H2S, NH3, or HCl is present has been solved, but the problem of sampling phosphine in atmospheres where acetylene evolves remains. Sampled filters and filter solutions are stable for more than three months at ambient temperature.

[Intramural hematoma of the esophagus: a rare diagnosis]

We describe three cases of spontaneous intramural hematoma of the esophagus, a rare pathology. The combination of chest pain, dysphagia and hematemesis and often the existence of hemostasis disorders or fragility of the mucosa, or trauma of the esophagus, should evoke the diagnosis. Radiology (thoracic scan, barium swallowing) and esophagoscopy enable confirmation of the diagnosis, permitting conservative treatment and simple spontaneous course of this pathology.

[Endoscopic sphincteroclasy for choledocholithiasis of the principal bile duct. Short-term results and follow-up]

AIMS

The hydrostatic dilatation of the papilla of Vater, or sphincteroclasy, has been recently proposed as an alternative to endoscopic sphincterotomy. Our aim was to assess short term results and follow-up after sphincteroclasy for choledocholithiasis.

METHODS

From August, 1994 to December, 1996, 52 patients were included for endoscopic therapy of choledocholithiasis (mean age 66 +/- 17 years). Patients were prospectively followed on the short term-period (24 h, 48 h and 30 days) and longer term after treatment (every 6 months) by clinical and biological controls.

MAIN RESULTS

Forty-eight sphincteroclasies were performed successfully (92.3%). Thirty seven patients had a choledocolithiasis. Eleven were stone-free. Eight had undergone former gastric surgery and 8 had impaired coagulation test. Complete stone clearance was achieved in 98% of patients. Mild pancreatitis were observed in three patients (6.25%). Thirty-day mortality was nil. Long term follow-up (mean 21.4 +/- 7 months) revealed: 2 patients with cholecystitis 6 and 13 months after treatment, one of which was followed 8 months later by a fatal septic shock, and 3 patients with cholangitis, 2 of which in the same patient, 9, 12 and 24 months after sphincteroclasy. The global long term biliary complication rate was 8.4%, 4.2% of which were potentially related to the endoscopic procedure.

CONCLUSION

Sphincteroclasy is an efficient procedure for the treatment of choledocholithiasis. Its short term results are similar to those of endoscopic sphincterotomy. Complications after 2 years appear to be scarce, but longer follow-up is required before routinely performing sphincteroclasy.

Use of magnetic resonance cholangiography in the diagnosis of choledocholithiasis: prospective comparison with a reference imaging method

BACKGROUND

Magnetic resonance cholangiography (MRC) is a new technique for non-invasive imaging of the biliary tract.

AIM

To assess the results of MRC in patients with suspected bile duct stones as compared with those obtained with reference imaging methods.

PATIENTS/METHODS

70 patients (34 men and 36 women, mean (SD) age 71 (15.5) years; median 75) with suspected bile duct stones were included (cholangitis, 33; pancreatitis, three; suspected post-cholecystectomy choledocholithiasis, nine; cholestasis, six; stones suspected on ultrasound or computed tomography scan, 19). MR cholangiograms with two dimensional turbo spin echo sequences were acquired. Endoscopic retrograde cholangiography with or without sphincterotomy (n = 63), endosonography (n = 5), or intraoperative cholangiography (n = 2) were the reference imaging techniques used for the study and were performed within 12 hours of MRC. Radiologists were blinded to the results of endoscopic retrograde cholangiography and previous investigations.

RESULTS

49 patients (70%) had bile duct stones on reference imaging (common bile duct, 44, six of which impacted in the papilla; intrahepatic, four; cystic duct stump, one). Stone size ranged from 1 to 20 mm (mean 6.1, median 5.5). Twenty seven patients (55%) had bile duct stones smaller than 6 mm. MRC diagnostic accuracy for bile duct lithiasis was: sensitivity, 57.1%; specificity, 100%; positive predictive value, 100%; negative predictive value, 50%.

CONCLUSIONS

Stones smaller than 6 mm are still often missed by MRC when standard equipment is used. The general introduction of new technical improvements is needed before this method can be considered reliable for the diagnosis of bile duct stones.

[Inflammatory fibroid polyps of the colon]

Inflammatory fibroid polyp is an uncommon lesion involving the stomach, the small bowel and occasionally the colon. Inflammatory fibroid polyp is a large polypoid lesion arising from the submucosa. It has no malignant potential although extensive infiltration may occur. The main histological characteristics are diffuse inflammatory infiltrate with eosinophils and highly vascularized fibrocytic stroma. Immunohistochemistry is always positive for vimentine and negative for S 100 and desmin. We report four cases of inflammatory fibroid polyps, 3 of which mimicked carcinoma of the colon. Exploratory laparotomy and histopathological examination of the resected specimen were necessary to confirm definitive diagnosis. In the last case, diagnosis was established by histological examination of an endoscopically-removed colonic polyp.

[Laparoscopic cholecystectomy and lithiasis of the common bile duct: prospective study on the importance of preoperative endoscopic ultrasonography and endoscopic retrograde cholangiography]

OBJECTIVES

Laparoscopic cholecystectomy is the standard treatment of symptomatic gallstones. At present, no consensus has been reached on the diagnostic and therapeutic methods of concomitant common bile duct stones. Systematic preoperative endoscopic ultrasonography followed, if necessary, by endoscopic retrograde cholangiography and sphincterotomy during the same anesthetic procedure could be a diagnostic and therapeutic alternative for common bile duct stones making possible a laparoscopic cholecystectomy without intraoperative investigation of the common bile duct.

METHODS

One hundred and twenty-five patients underwent a prospective endoscopic ultrasonographic evaluation prior to laparoscopic cholecystectomy for symptomatic gallstones. Fourty-four patients (35%) had at least one predictive factor for common bile duct stones. Endoscopic ultrasonography and cholecystectomy were performed on the same day. Endoscopic ultrasonography was followed by endoscopic retrograde cholangiography and sphincterotomy by the same endoscopist in case of common bile duct stones on endoscopic ultrasonography. Patients were routinely followed up between 3 and 6 months and one year after cholecystectomy.

RESULTS

Endoscopic ultrasonography suggested common bile duct stones in 21 patients (17%). Endoscopic ultrasonography identified a stone in 17 of 44 patients (38.6%) with predictor of common bile duct stones and only in 4 of 81 patients (4.9%) without predictor of common bile duct stone. Among these 21 patients, one patient was not investigated with endoscopic retrograde cholangiography because of the high risk of sphincterotomy, 19 patients had a stone removed after sphincterotomy, one patient had no visible stone neither on endoscopic retrograde cholangiography, nor on exploration of the common bile duct after sphincterotomy. Endoscopic ultrasonography was normal in 104 patients (83%). However, two patients in this group were investigated with endoscopic retrograde cholangiography because endoscopic ultrasonography was incomplete in one case and because endoscopic ultrasonography was normal in the second case but a stone in the left hepatic duct was detected by ultrasonography. A stone was removed after endoscopic sphincterotomy in these two patients. In the group of 102 patients without stone, 91 out of 92, continued to be asymptomatic during a median follow-up of 8.5 months. One patient with symptoms one month after cholecystectomy underwent endoscopic sphincterotomy but no stone was found.

CONCLUSIONS

Systematic preoperative endoscopic ultrasonography followed, if necessary with endoscopic retrograde cholangiography and sphincterotomy is a diagnostic and therapeutic alternative for common bile duct stones making possible a laparoscopic cholecystectomy without intraoperative investigation of the common bile duct for all patients. This alternative is only justifiable in patients with predictor of common bile duct stones.

[Intra-corporeal shockwave lithotripsy in the treatment of complex lithiasis of the bile ducts. Comparison of endoscopic techniques and long-term results]

OBJECTIVES

About 2% of common bile duct stones and most intra-hepatic stones cannot be removed by conventional endoscopy. Intra-corporeal lithotripsy is an alternative technique for these patients. Contact lithotripsy can be obtained by a pulsed dye laser or by electro-hydraulic shockwaves. We compared and assessed the results of these two methods.

METHODS

Thirty-seven patients (79 +/- 9.8 years, 25 women and 12 men) underwent laser lithotripsy (n = 21), electro-hydraulic lithotripsy (n = 9) or both methods consecutively (n = 7) for common bile duct stones (n = 31), intra-hepatic stones (n = 3) or diffuse lithiasis (n = 3). The mean diameter of the largest stone was 23 +/- 12 mm. Lithotripsy was performed by a retrograde approach in 35 cases and a combined, retrograde and transhepatic approach in 2 cases.

RESULTS

The mean number of lithotripsy sessions was 1.5 +/- 0.65. The overall success rate (free bile ducts with patent drainage) was 95%. In 2 patients, stones were not fully extracted: one underwent surgery, the other one was treated conservatively with antibiotics. The duration of the hospital stay was 9.3 +/- 4.5 days. Morbidity at 30 days was 27% and only one case of major morbidity (hemorrhage after sphincterotomy, 2.7%) was observed. There were no procedure-related mortality. Electro-hydraulic and laser groups did not differ significantly for success rate, morbidity and time spent at hospital. Follow-up information was obtained in 34 patients (91.8%) a median of 17 months after lithotripsy (range: 4.52 months). Ten patients died of non-biliary diseases. Two patients (5.8%) developed biliary symptoms 24 and 34 months after lithotripsy, one after unsuccessful lithotripsy.

CONCLUSION

Intra-corporeal lithotripsy is a valuable tool for the most complex cases of duct stones, and with an acceptable morbidity. The results of the two techniques are similar. Late biliary complications after intra-corporeal lithotripsy appear to be rare.

Predictive factors for survival of patients with inoperable malignant distal biliary strictures: a practical management guideline

BACKGROUND

Stenting is the treatment of choice for inoperable malignant strictures of the common bile duct. Criteria for the choice of stents (plastic versus metallic) remain controversial because predicting survival is difficult.

AIMS

To define prognostic factors in order to improve the cost effectiveness of endoscopic palliation.

PATIENTS

One hundred and one patients were included in a prospective trial. Seven prognostic variables for survival were analysed (age, sex, bilirubinaemia, weight loss, presence of liver metastases, and tumour histology and size). All patients were followed until death or at least one year after inclusion. By the end of the study, 81 (80.2%) patients had died.

RESULTS

In univariate analysis, the variables associated with survival were weight loss (p < 0.05) and tumour size (p < 0.01). By multivariate analysis, tumour size was the only independent prognostic factor (p < 0.05). A threshold of 30 mm at diagnosis distinguished two survival profiles: the median survival of patients with a tumour greater than 30 mm was 3.2 months, whereas it was 6.6 months for patients with a tumour less than 30 mm (p < 0.001).

CONCLUSIONS

A practical strategy could be based on tumour size at diagnosis: a metal stent should be systematically chosen for patients with an inoperable tumour smaller than 30 mm, while larger tumours are efficiently palliated by a plastic stent.

A randomized trial of endoscopic drainage methods for inoperable malignant strictures of the common bile duct

BACKGROUND

Although metallic stents remain patent longer than plastic stents, the optimal palliation of inoperable malignant biliary strictures remains controversial because of the high cost of metallic stents and short patient survival.

METHODS

A total of 101 patients (mean age 72.5+/-12.9 years) with malignant strictures of the common bile duct were included in this study, after three exclusions for technical failure (n = 3) and one for noncompliance with study design. The etiology of the strictures included pancreatic cancer (65), cholangiocarcinoma (21), ampullary tumor (3), and metastatic lymph nodes (12). Patients were randomized to receive either an 11.5F polyethylene stent to be exchanged in case of dysfunction (group 1, n = 33), an 11.5F stent to be exchanged every 3 months (group 2, n = 34), or a self-expanding metallic Wallstent (group 3, n = 34).

RESULTS

Endoscopic procedures were successful (including complete relief of jaundice) in 97.1 % of cases. Procedure-related morbidity was 11.9%, and mortality was 2.9%. Bilirubinemia after 48 hours (37.2%+/-21.7% decrease from the preoperative level) did not differ between groups. Patients were followed for a mean of 166 days (median 143, range 0 to 596 days). Overall survivals were not different between groups, but complication-free survival for groups 2 and 3 was longer than that of group 1 (p < 0.05). Cumulated hospital days were 7.4+/-1.5, 10.6+/-1.7, and 5.5+/-1.4 (groups 1, 2, and 3, respectively) (p < 0.05; analysis of variance). Cost analysis showed that metallic stents were advantageous in patients surviving more than 6 months, whereas a plastic stent was advantageous in patients surviving 6 months or less.

CONCLUSIONS

Metallic stents and plastic stents exchanged every 3 months are valuable alternatives for increasing complication-free survival in patients with malignant strictures of the common bile duct. Metal stents are advantageous in patients with the longest life expectancy.

Properties of chloride-conductive pathways in rat kidney cortical and outer-medulla brush-border membranes--inhibition by anti-(cystic fibrosis transmembrane regulator) mAbs

The activity of the Cl(-)-conductive pathways, their regulation by protein kinase A (PKA) and their relationship to the cystic fibrosis transmembrane regulator (CFTR) protein were assessed in rat kidney cortical brush-border-membrane vesicles (cBBMV) and outer medullary vesicles (OMV) by measuring the rate of valinomycin-induced microsomal swelling by light scattering in the presence of an inward Cl- gradient. Valinomycin increased the rate of swelling of cBBMV and OMV, which is consistent with the presence of a Cl(-)-conductive pathway. PKA further increased these rates. This effect was blocked by the inhibitor of protein kinase A, suggesting that phosphorylation by PKA activates these pathways. Four anion-transport inhibitors were tested ¿N-phenylanthranilic acid (PhNHPhCOOH), 5-nitro-2-(3-phenylpropylamino)benzoic acid [N(PhPrNH2)BzOH], glybenclamide and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid¿. Ph2COOH and 4-acetamido-4'-isothiocyanato-stilbene-2,2'-disulfonic acid inhibited the basal Cl(-)-conductive pathways, while PKA-treated microsomes were sensitive also to N(PhPrNH2)BzOH and glybenclamide, suggesting that additional Cl- pathways were activated by phosphorylation. The pharmacological properties of these pathways were similar to those of the CFTR Cl- channel. Two anti-CFTR mAbs inhibited PKA-activated valinomycin-induced swelling in cBBMV and OMV, while immunoblot analysis of the corresponding proteins with the same antibodies indicated the presence of a 170-kDa protein. The results thus indicate the presence of a PKA-activated Cl(-)-conductive pathway in cBBMV and OMV, and suggest that CFTR protein is involved in PKA-activated Cl- fluxes in these vesicles.

What role can endoscopy play in the management of biliary complications after laparoscopic cholecystectomy?

BACKGROUND AND STUDY AIMS

This study was carried out to establish the indications for biliary endoscopy due to biliary complications after laparoscopic cholecystectomy (LC).

PATIENTS AND METHODS

One hundred nineteen patients (36 men, 86 women; median age 59, range 16-93) were referred for endoscopic retrograde cholangiopancreatography (ERCP) to five centers between 1990 and 1994, and included in the study. The delay between LC and ERCP was 105 +/- 21 days.

RESULTS

Four types of complications were observed. a) Fifty-seven patients had residual stones or clip migration into the common bile duct (CBD); all were successfully treated with endoscopic sphincterotomy (ES). b) Twelve major injuries to the CBD were diagnosed by ERCP; successful surgical repair was carried out in most of these cases. c) Twenty patients had a partial biliary stricture; endoscopic stenting was attempted as a primary procedure in eight patients, with a satisfactory outcome in five (63%). d) Thirty patients had a bile leak; endoscopic therapy (26 patients) led to recovery in 18 (69%). The benefit of endoscopic treatment was less clear in five (19%); ES failed to bring about improvement in three patients (12%).

CONCLUSIONS

ERCP is indicated when a biliary complication is suspected after laparoscopic cholecystectomy. Endoscopic sphincterotomy is effective for the treatment of retained stones, clip migration, and bile leakage. Endoscopic stenting may be offered as a primary option in partial CBD strictures.

Osmosensitivity of the hyperpolarization-activated chloride current in human intestinal T84 cells

The osmosensitivity of the hyperpolarization-activated chloride current (I(Clhyp)) in T84 cells was studied using the whole cell patch-clamp recording configuration. Hypotonicity is known to activate an outwardly rectifying chloride current (HIORC) distinct from I(Clhyp) in these cells. The differing sensitivities of HIORC and I(Clhyp) toward inhibitors (1,9-dideoxyforskolin blocked HIORC but not I(Clhyp), and Cd2+ inhibited I(Clhyp) but not HIORC) allowed us to investigate the osmoregulation of I(Clhyp). Hypotonicity induced an increase in I(Clhyp) amplitude. Protein phosphatase inhibitors prevented this effect, and hypotonic solutions became slightly inhibitory. Hypertonicity resulted in a transient increase in I(Clhyp) amplitude followed by a large decrease. The complex responses of I(Clhyp) to osmotic changes indicate that these signals affect the same channel via multiple transduction pathways. The responses of I(Clhyp) to hypotonicity have features in common with the responses of ClC-2 channels expressed in Xenopus oocytes (activation) and with hyperpolarization-activated chloride currents in other cell types, such as osteoblasts and mandibular duct cells (inhibition).

Endoscopic sphincteroclasy: a useful therapeutic tool for biliary endoscopy in Billroth II gastrectomy patients

BACKGROUND AND STUDY AIMS

Endoscopic exploration of the common bile duct is generally more difficult and hazardous in patients with a Billroth II gastrectomy than in patients with normal anatomy. Hydrostatic dilation of the papilla, which we term "endoscopic sphincteroclasy", provides a useful alternative to sphincterotomy in such patients.

PATIENTS AND METHODS

Endoscopic sphincteroclasy was carried out in five patients with a Billroth II anastomosis. There were four men and one woman, aged 58 to 90 years. One patients was cirrhotic, with impaired coagulation. Four presented with typical cholangitis, and one had pain and jaundice. The common bile duct was dilated in all five patients. Four had choledocholithiasis and one had a cholangiocarcinoma.

RESULTS

Sphincteroclasy was carried out with balloon dilators mounted on 0.035-inch guide wires. Immediate extraction of stones was achieved in three of the four patients with choledocholithiasis. In one case, a control endoscopic retrograde cholangiopancreatography was necessary to remove residual stones, without additional dilation. Insertion of the endoprosthesis was possible without difficulty in the patient with a malignant stricture. None of the patients required a sphincterotomy. No complications were observed up to six months after the sphincteroclasy.

CONCLUSIONS

We recommend the use of endoscopic sphincteroclasy in patients with a Billroth II gastrectomy who require endoscopic therapy, as well as in patients in need of emergency bile duct decompression who have impaired coagulation.

Partial purification of the pig kidney cystic fibrosis transmembrane regulator protein

The cystic fibrosis transmembrane conductance regulator (CFTR) is a transmembrane protein that is expressed in several epithelia, including kidney tubules. Mutations in CFTR (a PKA-chloride channel and/or regulator of other epithelial channels) give rise to the clinical manifestation of cystic fibrosis, and result in the synthesis of mutated proteins responsible for altering ion transport across secretory epithelia. The low abundance of endogenous CFTR makes a difficult to purify enough of the native protein to prepare anti-CFTR antibodies. We have used differential centrifugation to prepare cortical brush border membrane vesicles from pig kidney, cBBMV, and developed a method for the partial purification of CFTR. This is the first step in the isolation of native CFTR. The results show that CFTR is present in cBBMV. The purified protein will provide a clearer picture of the biophysical and biochemical properties of native CFTR.

Properties of a Cl(-)-conductive pathway(s) in microsomes from rat kidney inner medulla. Involvement of cystic fibrosis transmembrane regulator protein

The properties of a protein-kinase-A(PKA)-activated Cl(-)-conductive pathway(s) in alkaline phosphatase-enriched microsomes from the rat inner medulla (IMV) were investigated. Transcripts of cystic fibrosis transmembrane regulator (CFTR) were detected by reverse transcription/polymerase analysis of total RNA from the inner medulla, while immunoblot analysis using anti-CFTR antibodies detected a 170-kDa protein in the IMV. The PKA Cl(-)-conductive pathway(s) was studied by measuring the rate of valinomycin-induced microsomal swelling by light scattering. PKA increased the rate of valinomycin-induced swelling of vesicles consistent with the presence of Cl(-)-conductive pathway(s). The pharmacological properties and anion selectivity of the PKA-activated Cl(-)-conductive pathway(s) were similar to those of the CFTR Cl(-) channel. Our results show that a CFTR Cl(-) channel and possibly another cAMP-activated pathway(s) may participate in Cl(-) secretion in the rat inner medulla.

Biliary obstruction caused by portal cavernoma: a study of 8 cases

BACKGROUND/AIMS

Biliary obstruction secondary to portal cavernoma is a rare and little-known entity. From 1985 to 1994, we observed eight cases of portal cavernoma compressing the biliary tract. We report here the features of biliary involvement in these cases of portal cavernoma including the circumstances of diagnosis, biliary tract morphology, liver pathology and the efficiency of various treatments.

METHODS AND RESULTS

The causes of portal vein obstruction were portal vein thrombosis in one case, peritonitis in another, omphalitis in two cases, portal vein catheterization in one case and unknown in two cases. The portal cavernoma was revealed through esophageal varices ruptures in four patients. The mean time from portal cavernoma diagnosis to biliary involvement was 8 years (range 0-21). Six patients had acute cholangitis, one of whom revealed portal vein obstruction. All the patients had abnormal liver function tests. Imaging techniques (transparietal abdominal ultrasonography and abdominal computed tomography scan [n = 8], endosonography [n = 5] and endoscopic retrograde cholangiography [n = 7]) showed in all cases an extraluminal obstacle, laminating the common bile duct. Pathologic examination of the liver showed secondary biliary cirrhosis in one patient, periportal and perisinusoidal fibrosis in another and no abnormalities in three other cases. Three patients were treated by endoscopic sphincterotomy but cholangitis persisted in two cases, leading to death in one. One patient who underwent a splenorenal shunt was symptom-free 60 months after surgery. Balloon endoscopic dilatation of the common bile duct, performed in one case, led to normalization of liver biological tests. The patients with abnormal liver pathology were treated by propranolol and ursodesoxycholic acid. No complication had occurred after 6 and 24 months of follow-up.

CONCLUSIONS

In conclusion, eliminating biliary obstruction seems to be essential in providing the best change of survival for patients when biliary obstruction becomes symptomatic. In cases of abnormal liver pathology, associating propranolol with ursodesoxycholic acid would seem to be useful.

Biliary symptoms and complications more than 8 years after endoscopic sphincterotomy for choledocholithiasis

BACKGROUND & AIMS

Although long-term results of endoscopic sphincterotomy (ES) have been poorly estimated, extended indications of ES have been proposed, especially in young patients. The aim of this study was to assess late biliary complications of ES.

METHODS

Between 1981 and 1986, 169 patients younger than age 70 (55+/-11.8 years; range, 24-70 years; male-female sex ration, 0.55) underwent ES for choledocholithiasis. One hundred fifteen patients (68%) underwent cholecystectomy. Long-term data were obtained retrospectively from the patients and general practitioners.

RESULTS

Information was obtained for 156 patients, 2 of whom died within 1 month (one ES-related death). The mean follow-up for 154 patients was 9.6+/-3.3 years (range 8-13 years); 138 patients had no biliary symptoms. During follow-up, 16 patients experienced biliary symptoms; 2 of these patients underwent elective cholecystectomy, 3 had malignant strictures, 1 had a complicated cirrhosis, and 1 had a benign stricture related to the previous cholecystectomy. Nine patients developed potentially ES-related biliary symptoms. Second endoscopic exploration showed papillary stenosis in 3 patients (with stones in 2 patients) and recurrent bile duct stones in 3 others. Two patients had sine materia cholangitis, and 1 patient developed liver abscesses.

CONCLUSIONS

Long-term ES-related complications seem to be rare, ES could reasonably be included in management strategies of choledocholithiasis, even in young patients.

Endoscopic sphincterotomy in patients with liver cirrhosis

BACKGROUND

Nonsurgical alternatives in biliary diseases have not been studied in large series of patients with cirrhosis. Our aim was to determine the indications and results of endoscopic treatment in this subset of patients.

METHODS

Fifty-two patients (36 men, 16 women-Child-Pugh Class A, 18; B, 22; C, 12) aged 63 +/- 18 years underwent endoscopic sphincterotomy (ES) between 1988 and 1993. Antibiotic prophylaxis was routinely carried out and coagulopathy was corrected before ES when required. The data were collected retrospectively up to 30 days after ES.

RESULTS

ES succeeded in 98% of the patients (12 cases of needle-knife papillotomy). Twenty-nine patients (55.7%) had choledocholithiasis, 18 had biliary strictures (12 malignant), and 5 had pancreatic or other biliary diseases. Five days after ES, morbidity was 13.5% and mortality was 7.7%. At 1 month, morbidity was 22.9% and mortality 12.5%. Only endoscopic procedures and Ineffective drainage were seen to be significant risk factors or morbidity. The results of the subgroup of cirrhotic patients with choledocholithiasis (n = 29) were compared with those of matched noncirrhotic patients (n = 58). The cirrhotic and noncirrhotic patients treated for choledocholithiasis showed similar results for stone clearance, morbidity, and mortality.

CONCLUSION

ES is a safe and effective procedure for treating choledocholithiasis in cirrhotic patients. ES can therefore be considered as an alternative to surgery in Child class A and B patients and must be preferred for Child class C patients with life-threatening biliary complications.

Bile levels of carcino-embryonic antigen in patients with hepatopancreatobiliary disease

OBJECTIVE

To evaluate the value of biliary carcino-embryonic antigen (CEA) in the differential diagnosis of malignant and benign hepatopancreatobiliary disease.

PATIENTS

One hundred patients were prospectively studied. Benign diseases were present in 39% of the patients while 61% had malignant diseases.

METHODS

Samples of serum were taken from all patients just before endoscopic retrograde cholangiopancreatography (ERCP) and samples of biliary CEA were obtained during ERCP.

RESULTS

The sensitivity of serum CEA and carbohydrate antigen 19-9 (CA 19-9) in detecting malignancy were 50% and 92%, respectively, while the respective specificities were 95% and 72%. The mean biliary CEA level of the benign group was significantly different from that of the malignant group (35.7 +/- 8.7 ng/ml vs 268 +/- 85.5 ng/ml), but there was considerable overlap between the two groups. With a cut-off level of 20 ng/ml, the sensitivity and specificity were 84% and 64% respectively. The mean bilirubinaemia value was significantly higher in malignant disease than in benign disease (57.4 +/- 13.9 mumol/l vs 235 +/- 19.8 mumol/l). Multidimensional analysis indicated that only bilirubinaemia (P < 109-3)) was independently predictive of malignant disease.

CONCLUSION

Biliary CEA assessment seems useless in distinguished between benign and malignant causes of cholestasis.

Prospective controlled study of endoscopic ultrasonography and endoscopic retrograde cholangiography in patients with suspected common-bileduct lithiasis

BACKGROUND

Endoscopic sphincterotomy is sometimes done unnecessarily in patients with suspected choledocholithiasis. Our aims were to assess the diagnostic accuracy of endoscopic ultrasonography and endoscopic retrograde cholangiography (ERC) and to find out whether endoscopic ultrasonography may help to prevent unnecessary sphincterotomy or surgical explorations.

METHODS

We recruited 119 patients aged 70.4 (SD 16.1) years with strongly suspected choledocholithiasis who presented to our endoscopy unit between January, 1994, and January, 1995. During the same spell of sedation or within 2 h of each other, endoscopic ultrasonography and ERC were carried out by investigators unaware of the patient's history. Endoscopic sphincterotomy with instrumental exploration was then done as the gold standard for the presence or the absence of stones.

FINDINGS

78 (66%) patients had choledocholithiasis; 17 (14%) had other bileduct diseases; 24 (20%) had a clear bileduct or did not require an invasive endoscopic procedure. The sensitivity of endoscopic ultrasonography was 93%, specificity 97%, positive predictive value 98%, and negative predictive value 88%. The corresponding values for ERC were 89%, 100%, 100%, and 83%. There were five false-negative cases by endoscopic ultrasonography (of which three were also negative with ERC) and one false-positive. The morbidity rate was 4.1%.

INTERPRETATION

We conclude that endoscopic ultrasonography is at least as sensitive as ERC. Endoscopic ultrasonography may prevent inappropriate invasive explorations of the common bileduct.

[Prevention of hemorrhagic recurrences caused by rupture of esophageal varices, with endoscopic ligation. Prospective study of 50 patients]

OBJECTIVES

Endoscopic sclerotherapy is effective to prevent bleeding of oesophageal varices but is associated with frequent adverse effects. Endoscopic ligation represents a new endoscopic alternative treatment to sclerotherapy. The purpose of this study was to assess efficacy and safety of endoscopic variceal ligation in 50 consecutive patients with cirrhosis who had recently bled from oesophageal varices.

METHODS

Patients were followed from 6 to 1140 days (median 310 days). Nine patients were bleeding actively when ligation was performed.

RESULTS

Eleven patients (22%) had 13 recurrent bleedings requiring blood transfusion during follow-up. Six recurrences occurred during the first month (3 from bleeding varices, 3 treatment-induced); seven recurrences occurred latter (6 from bleeding varices, 1 treatment-induced). Varices were eradicated in 33 patients (66% of all patients, 82% of patients who survived more than 30 days). Variceal eradication was achieved in 2-9 endoscopic ligation sessions (median 3). Eighteen patients died during the study; one died from bleeding. No patient developed major complications; five patients only complained of mild dysphagia for 24 to 48 hours.

CONCLUSION

Endoscopic ligation is a safe and effective method to prevent recurrent bleeding from oesophageal varices.

Modulation of the hyperpolarization-activated Cl- current in human intestinal T84 epithelial cells by phosphorylation

1. Hyperpolarization-activated Cl- currents (ICl,hyp) were investigated in the T84 human adenocarcinoma cell line, using the patch-clamp whole-cell configuration. 2. During whole-cell recording with high-chloride and ATP-containing internal solutions, hyperpolarizing jumps from a holding potential of 0 mV elicited slow inward current relaxations, carried by Cl- and detected at membrane potentials more negative than -40 mV. Analysis of the relative permeabilities to monovalent anions gave the following sequence: Cl- > Br- > I- > glutamate. 3. ICl,hyp was partially inhibited by 1 mM diphenylamine-2-carboxylic acid or 0.1 mM 5-nitro-2-(3-phenylpropylamino)-benzoate, and was completely blocked by Cd2+ (> 300 microM). It was insensitive to 1 mM external 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid or 1 mM Ba2+. 4. ICl,hyp was inhibited by external application of 500 microM cptcAMP (8-(4-chlorophenylthio)-adenosine 3':5'-cyclic monophosphate) or 500 nM of the protein kinase C activator, phorbol 12-myristate, 13-acetate. 5. (i) Omission of ATP from the pipette solution, (ii) ATP replacement by the non-hydrolysable ATP analogue 5'-adenylylimidodiphosphate, and (iii) inhibition of protein kinase C by staurosporine or calphostin C accelerated the activation kinetics of the current and increased its amplitude, but did not alter its pharmacological properties. 6. We conclude that hyperpolarization-activated Cl- channels similar to those of ClC-2 channels (mammalian homologue of Torpedo chloride channel ClC-0) are present in T84 cells, and that their gating properties are modulated by phosphorylation.

Cholangiographic features in fibrosis and cirrhosis of the liver. Radiological-pathological correlation

The cholangiographic features of intrahepatic bile ducts associated with cirrhosis or fibrosis are not well known. In order to achieve a radiological-pathological correlation, we studied nine livers with fibrosis or cirrhosis excised at autopsy. Cholangiograms were obtained within 24 hr after death from the nonfixed liver and multiple tissues samples were taken for histologic examination. Radiological data were interpreted by two independent investigators blinded to the clinical and histological findings. Cirrhosis (alcoholic in 4, posthepatitis in two) was observed in six livers, fibrosis (alcoholic in 2, posthepatitis in one) in three. No liver with fibrosis had cholangiographic abnormalities. In contrast, cholangiography of all livers with cirrhosis was abnormal. Abnormalities were a diminished arborization, a decrease of the distal opacification, an irregularity of caliber, and a tortuous course of the bile ducts. Histological study showed that the irregular and tortuous course were due to compression of the bile ducts by regenerative nodules. Furthermore, a thick fibrosis was organized around the bile ducts. In conclusion, fibrosis alone was not associated with cholangiographic abnormalities. In cirrhotic livers, intrahepatic bile ducts showed an irregular and tortuous course, a diminished arborization and a decrease of the distal opacification. These abnormalities were secondary to the presence of regenerative nodules and fibrosis organized around the bile ducts.

Diagnostic ERCP in the era of laparoscopic surgery

BACKGROUND/AIMS

The purpose of this paper is to reassess the place and risks of ERCP in a diagnostic view.

METHODS

Analysis of 196 non-operative ERCP performed in 196 patients aged 57 +/- 20 yrs. ERCP was performed for: unexplained cholestasis = 98; non tumoral pancreatic diseases = 43; suspected neoplasm of the pancreatic/biliary tract = 13; cholangitis = 12; unexplained abdominal pain = 30. Precut papillotomy was performed in 40 cases (20.4%). 10.7% were cirrhotics; 3.1% were gastrectomized. 164/196 received peri-operative broad-spectrum antibiotics.

RESULTS

108 had normal ERCP (group I); 74 had abnormal ERCP (group II); 12 had undetermined diagnosis after ERCP (group III). Strictly ERCP-induced mortality was nil; 2 patients died a few days after ERCP from: hemorrhage after transhepatic drainage (1); continuing severe cholangitis after failed CBD cannulation (1). Morbidity was: acute pancreatitis = 6 (3%) and fever = 4 (2%). No complication followed precut papillotomy. The 6 pancreatitis recovered within 48 h to 5 days. Fevers alleviated with antibiotics within 12 to 48 h. Pancreatitis occurred in 5/6 after normal ERCP; fevers followed pathologic ERCP in 3/4 (NS). The high rate of precuts in this series did not increase morbidity.

CONCLUSION

ERCP-related morbidity was 5.1 % and ERCP accurately diagnosed or unequivocally eliminated biliary-pancreatic disease in 92.9%. These results suggest that ERCP remains a useful and safe diagnostic tool.

Diagnosis and prognosis of AIDS-related cholangitis

OBJECTIVE

To determine more precisely the clinical and biological characteristics of AIDS-related cholangitis, and to investigate prognostic variables of this disease.

DESIGN

Retrospective clinical and prognostic study.

SETTING

Biliary unit, Bicêtre Hospital, France.

PATIENTS

HIV-positive patients (n = 52) referred to the unit between December 1986 and June 1993 for biliary symptoms leading to the suspicion of AIDS-related cholangitis, (42 men; 10 women; mean age, 37 +/- 8 years).

INTERVENTION

Endoscopic retrograde cholangiopancreatography (ERCP) was performed in order to determine the cause of the biliary symptoms.

MAIN OUTCOME MEASURE

Clinical features and evolution of the cholangitis.

RESULTS

Among the 52 patients, 45 met the ERCP criteria of AIDS-related cholangitis (36 men; nine women). The diagnosis of cholangitis was strongly suggested by abdominal ultrasonography in 47% of the cases. ERCP showed papillary stenosis, diffuse cholangitis, extrahepatic cholangitis alone, and intrahepatic cholangitis alone in 60, 67, 7 and 27%, respectively. Endoscopic sphincterotomy was performed in 28 patients. Pain was relieved by sphincterotomy in nine patients, but the other clinical or biological features were not influenced. One-year and 2-year survival rates were 41 +/- 7% and 8 +/- 4%, respectively. Multidimensional analysis using a Cox model showed that a lymphocyte count > 500 x 10(6)/l was the only independent predictive factor of better survival.

CONCLUSION

AIDS-related cholangitis is a disease which leads preferentially to papillary stenosis or diffuse abnormalities of the biliary tract. Prognostic factors depend on the stage of the HIV infection. Another diagnosis of cholestasis was found in approximately 15% of the patients who showed biliary symptoms.

Endoscopic sphincterotomy for suspected choledocholithiasis in patients with and without stones

OBJECTIVE

To characterize a subgroup of patients treated with endoscopic sphincterotomy (ES) for a suspected common bile duct lithiasis (CBDL) that was not confirmed and to compare it with the subgroup with confirmed CBDL.

METHODS AND RESULTS

Over 18 months, ES was successful in 245 consecutive patients (age 23-97, mean 75 yr, SE 17 yr) with suspected CBDL; 159 patients had CBDL (group 1), and 86 did not (group 2), as confirmed by CBD exploration. Fifty-nine percent of the patients in group 1 and 76.7% of the patients in group 2 had gallbladder in situ. Both groups were different for age (p < 0.001), prevalence of chronic alcoholism (p < 0.001), gallbladder in situ (p < 0.01), and gallbladder stones (p < 0.05). Patients from group 1 had two or more presenting symptoms suggestive of CBDL more often than patients from group 2 (p < 0.05), and pancreatitis was a more frequent presenting manifestation in group 2 (p < 0.0001). Overall morbidity and mortality were not different between groups, but acute cholecystitis developed in six patients from group 2 and in one patient from group 1 (p < 0.01). In a univariate analysis, only elevated alkaline phosphatase and a dilated common bile duct were positively discriminant for the diagnosis of CBDL; chronic alcoholism was negatively discriminant for the diagnosis of CBDL. In a multivariate analysis, only chronic alcoholism and a dilated bile duct were found to be independently discriminant.

CONCLUSION

The risk of ES-related complications in the group without CBDL suggests that the selection of patients should be improved by a better use of preoperative criteria.

Identification of an mRNA element promoting rate-limiting cleavage of the polycistronic puf mRNA in Rhodobacter capsulatus by an enzyme similar to RNase E

We have identified an mRNA element that is involved in the initial cleavage of the pufBALMX mRNA species in Rhodobacter capsulatus. This endoribonuclease recognition site, the first to be identified in a bacterial species other than Escherichia coli, shows strong similarities to mRNA sequences cleaved by the endoribonuclease E in E. coli. The presence of an RNase E-like enzyme in R. capsulatus is further supported by in vitro cleavage of E. coli transcripts by R. capsulatus extracts at sites attributed to RNase E and by the cross-reaction of a polypeptide from R. capsulatus with antisera against E. coli RNase E. Our data provide evidence that mRNAs are degraded in different bacterial species by enzymes with similar recognition sequences and activities. We present a model that attributes the segmental differences in stability of the polycistronic puf transcript to a specific distribution of mRNA decay-promoting and mRNA decay-impeding elements.

Dual modulation of the L-type calcium current of rat osteoblastic cells by parathyroid hormone: opposite effects of protein kinase C and cyclic nucleotides

Using whole-cell voltage-clamp recording of rat osteoblastic cells, we show that PTH-(1-34), known to stimulate protein kinase C (PKC) and adenylate cyclase, has a dual effect on the L-type calcium current. It induces a long-lasting increase and a superimposed reversible decrease, which can be separated by repeating hormone applications. The stimulatory effect is the only effect induced by the (3-34) fragment, able to stimulate PKC but unable to stimulate adenylate cyclase. The L current is stimulated by an active phorbol ester and is reduced by permeable analogues of cyclic AMP. Thus, the effect of PTH-(1-34) can be explained by the opposite effects of PKC and cyclic AMP. Dibutyryl cyclic GMP reduces the L current even more potently than dibutyryl cyclic AMP. The above modulations are all voltage-insensitive. These results led us to reinvestigate the effects of some vitamin D3 metabolites known to stimulate PKC and/or guanylate cyclase, and previously reported to affect the voltage-sensitivity of the L current. We only detected voltage-insensitive effects.

Activation of hyperpolarization and atypical osmosensitivity of a Cl- current in rat osteoblastic cells

During whole-cell recording of rat osteoblastic cells with high-Cl- internal solutions, 10 sec hyperpolarizing jumps from 0 mV induce a slow inward current relaxation, which is shown to be carried by hyperpolarization-activated Cl- channels. This relaxation increases and becomes faster with stronger hyperpolarizations. It is insensitive to Cs+ ions but is blocked in a voltage-dependent manner by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) 1 mM and is reduced by 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) 0.1 mM. Cd2+ ions are potent blockers of this current, blocking completely above 300 microM. The amplitude of the Cl- current activated by a given hyperpolarization increases during the first 10-20 min of whole-cell recording. This evolution and the fact that some recently cloned Cl- channels have been reported to be activated both by hyperpolarization and by external hyposmolarity led us to investigate the effects of external osmolarity. Reducing the external osmolarity induces a large Cl- current. However, this hyposmolarity-induced Cl- current and the hyperpolarization-activated Cl- current are shown to be distinct; 1,9-dideoxy forskolin selectively blocks the hyposmolarity-activated current. We show that the hyperpolarization-activated Cl- current is osmosensitive, but in an unusual way: it is reduced by external hyposmolarity and is increased by external hyperosmolarity. Furthermore, these modulations are more pronounced for small hyperpolarizations. The osmosensitivity of the hyperpolarization-activated Cl- current suggests a mechanosensitivity (activation by positive external pressure) that is likely to be physiologically important to bone cells.

Laser lithotripsy of difficult biliary stones

From June 1991 to September 1992, 16 patients (mean age, 72 +/- 5 years) were treated with intra-corporeal laser lithotripsy (ICL). Thirteen patients had choledocholithiasis with at least one stone larger than 20 mm; 3 patients had intra-hepatic lithiasis. All other methods, including mechanical lithotripsy, extra-corporeal lithotripsy (1 case), and intra-corporeal electrohydraulic lithotripsy (1 case), had failed to clear the bile ducts. Approaches for ICL were choledochoscopy with a "baby" endoscope via an existing sphincterotomy (8 cases), retrograde cholangioscopy with a gastroscope through a choledochoduodenal anastomosis or a sphincterotomy in patients with a gastrojejunal anastomosis (5 cases), and trans-hepatic cholangioscopy with a fibercholangioscope (3 cases, in 1 of which retrograde and trans-hepatic approaches were combined). Free bile ducts were obtained in 14/16 (87.5%) patients after a mean of 1.66 ICL sessions per patient. Mortality and laser-related morbidity did not occur; endoscopy-related morbidity was 12.5% for minor complications (1 transitory fever, 1 mild and transitory hemobilia) and 6.25% for major complications (1 post-sphincterotomy hemorrhage). Mean length of hospital stay was 11.5 +/- 2.5 days. We conclude that although it is rarely indicated and is expensive, ICL does offer a limited treatment option in selected patients. It allows the complete relief of complex biliary lithiasis. Morbidity is related to maneuvers preceding ICL, not to ICL itself.

Concentration-dependent modulations of potassium and calcium currents of rat osteoblastic cells by arachidonic acid

We show that the voltage-gated K+ and Ca2+ currents of rat osteoblastic cells are strongly modulated by arachidonic acid (AA), and that these modulations are very sensitive to the AA concentration. At 2 or 3 microM, AA reduces the amplitude and accelerates the inactivation of the K+ current activated by depolarization; at higher concentrations (> or = 5 microM), AA still blocks this K+ current, but also induces a very large noninactivating K+ current. At 2 or 3 microM, AA enhances the T-type Ca2+ current, close to its threshold of activation, whereas at 10 microM, it blocks that current. AA (1-10 microM) also blocks the dihydropyridine-sensitive L-type Ca2+ current. Thus, the effect of AA on Ca2+ entry through voltage-gated Ca2+ channels can change qualitatively with the AA concentration: at 2 or 3 microM, AA will favor Ca2+ entry through T channels, both by lowering the voltage-gated K+ conductance and by increasing the T current, whereas at 10 microM, AA will prevent Ca2+ entry through voltage-gated Ca2+ channels, both by inducing a K+ conductance and by blocking Ca2+ channels.