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J Fritsch

Publications and source records attributed to J Fritsch.

At least 19 recordsLinked to original sources
PubMed2001

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)].

Journal Article↗
PubMed2001

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

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-alpha (TGF-alpha) modulates ClC-2 activity in human colonic epithelial (T84) cells. TGF-alpha (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-alpha. 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-alpha was shown to reversibly alkalinize T84 cells at 8.3 nM but not at 0.17 nM, suggesting that 8.3 nM TGF-alpha-induced alkalinization activates ClC-2 current. This study indicates that ClC-2 channels are targets for EGFR signaling in epithelial cells.

Biological Transport↗
PubMed2000

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.

Cystic Fibrosis↗
PubMed2000

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.

Environmental Monitoring↗
PubMed2000

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

UNLABELLED: 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.

Actuarial Analysis↗
PubMed1999

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.

Adult↗
PubMed1999

[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.

Adult↗
PubMed1999

[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.

Adult↗
PubMed1998

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.

Adult↗
PubMed1998

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.

Adult↗
PubMed1998

[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.

Aged↗
PubMed1998

[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.

Adult↗
PubMed1997

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.

Animals↗
PubMed1997

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.

Aged↗
PubMed1997

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.

Adolescent↗