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Biomedical subjects

H Neuhaus

Publications and source records attributed to H Neuhaus.

At least 91 records · Page 5Linked to original sources
PubMed1992

Endoscopic laser lithotripsy with an automatic stone recognition system for basket impaction in the common bile duct.

In a patient with a common bile duct stone 28 mm in diameter, the traction wires of two basket catheters fractured during endoscopic mechanical lithotripsy. Disintegration of the concrement and removal of the impacted baskets failed even after extracorporeal application of 8,000 shockwaves. Pulsed dye laser lithotripsy was carried out via a 250 microns fiber which was advanced to the stone through a 6 French ERCP guiding catheter. Lithotripsy could be safely performed under fluoroscopic control since the laser used provides an automatic cut-out system upon tissue contact. 3,600 of 11,800 applied pulses were emitted with the total power setting and complete disintegration of the calculus was achieved. The baskets and the fragments could be removed endoscopically in the same session. Laser lithotripsy with a stone recognition system would seem to improve the applicability and safety of intracorporeal lithotripsy even when performed without direct visual guidance.

Aged↗
PubMed1992

Prospective evaluation of the use of endoscopic retrograde cholangiography prior to laparoscopic cholecystectomy.

Preoperative cholangiography and subsequent removal of bile duct stones may increase the efficacy of laparoscopic cholecystectomy and reduce the rate of conversion to open cholecystectomy. Since there is little data on the incidence of choledocholithiasis in this group of patients, we undertook a prospective study on the routine performance of ERC in 288 patients selected for laparoscopic cholecystectomy. ERC succeeded in 264 of the 288 patients (91.7%) and showed a normal bile duct system in 227 (86.0%). Atypical bile duct anatomy was seen in eight patients. Open cholecystectomy was performed in seven of them but was judged to be absolutely necessary in only two cases (one patient each with Caroli syndrome and Mirizzi syndrome). ERC also revealed bile duct stones in 29 of 264 patients (11.0%) which had not been suspected on the basis of clinical, laboratory and ultrasonographic findings in nine cases (3.4%). EPT succeeded in all of the 29 patients with choledocholithiasis but open cholecystectomy was subsequently performed in four patients due to incomplete bile duct clearance (n = 3) or temporary bleeding after EPT (n = 1). The rate of ERC/EPT-related morbidity was 2.8%. It is concluded from a risk-benefit analysis in these patients that ERC should be restricted to patients with suspected bile duct stones. Following this strategy, small ductal concrements and bile duct abnormalities will be missed in 6.4% of cases but the clinical relevance of these findings is still unclear. In patients with combined gallbladder and common bile duct stones, preoperative EPT plus subsequent laparoscopic cholecystectomy appears to be an effective and time-saving therapeutic regimen which should be compared with open cholecystectomy plus common bile duct exploration in future studies.

Bile Duct Diseases↗
PubMed1992

[Role of cholangiography in laparoscopic cholecystectomy].

Cholangiography in laparoscopic cholecystectomy is indicated for the detection of bile duct stones and for visualization of the biliary anatomy in particular cases. For a selective approach patients with gallbladder stones can be split into groups with a low, an intermediate and a high probability of choledocholithiasis by use of ultrasonographic and laboratory parameters. In this respect, the choledochal diameter is the most accurate criterion for the prediction of duct stones. A narrow lumen, detectable in almost one-half of the patients, indicates a less than 4% incidence of duct stones. Cholangiography seems to be unnecessary in this low risk group. However, endoscopic retrograde cholangiography (ERC) or intraoperative cholangiography is indicated in patients with a 7-12 mm width of common bile duct and/or an elevated serum bilirubin level due to 10-50% risk of choledocholithiasis. There are several therapeutic options in case of detected duct calculi. To date, laparoscopic bile duct clearance can not be reliably performed. In about 15% of the patients an even larger choledochol diameter is associated with a high chance of bile duct stones. ERC and in case of detected stones endoscopic papillotomy (EPT) should be routinely performed in these patients to facilitate elective laparoscopic cholecystectomy.

Cholangiography↗
PubMed1991

[Endoscopic papillotomy (sphincterotomy) in the 1990-s].

This review summarizes the past history and presence of endoscopic papillotomy (EPT, sphincterotomy) in the treatment of biliary and pancreatic tract diseases. The indications of the different techniques used, and the comparison of the effectiveness of EPT with that of the traditional surgical treatment is also discussed. Based on the results, EPT is an up-to-date technique with good effectiveness, low risk for patients and widening indication range. EPT in the future, will play a determining role in the effective treatment of biliary and pancreatic tract diseases.

Ampulla of Vater↗
PubMed1991

Cloning and expression of cDNAs for the alpha subunit of the murine lymphocyte-Peyer's patch adhesion molecule.

cDNA clones encoding the alpha chain of the murine lymphocyte-Peyer's patch adhesion molecule (LPAM), which is associated with lymphocyte homing, have been isolated by screening with the human VLA-4 (alpha 4h) probe. Several alpha 4 antigenic determinants were identified on COS-7 cells after transfection. From overlapping clones, approximately 5 kb of contiguous nucleotide sequence have been determined, encoding a protein sequence of 1039 amino acids for the LPAM alpha chain (alpha 4m). LPAM is a member of the integrin family of cell-surface heterodimers, and alpha 4m is the murine homologue of the human alpha 4 h chain. The two proteins have a total sequence similarity of 84%, with an almost perfect conservation (31/32 amino acids) in the cytoplasmic domain. Like alpha 4h, alpha 4m is distinct from other integrin alpha chains because it has neither an I-domain nor a COOH-terminal cleavage site. The positions of the characteristic Cysteine residues are conserved, and a putative protease cleavage site is located near the middle of the protein sequence. The NH2-terminal part of the protein contains seven homologous repeats, and three of them include putative divalent cation-binding sites. These sites are among the most conserved between the alpha 4m sequence and other alpha chains, and may therefore be involved in the binding of integrin alpha and beta chains. An additional cDNA clone was isolated which shares a sequence of perfect homology with the alpha 4m encoding cDNAs, but has a unique 3' poly-A end. This observation correlates with the fact that three discrete murine RNA bands are observed in Northern blot experiments using alpha 4m as a probe, whereas only two human RNA species are described for alpha 4h, indicating a higher complexity for murine than for human sequences.

Amino Acid Sequence↗
PubMed1991

[Self-expanding and expandable bile duct prostheses].

The main problem of conventional endoscopic or percutaneous biliary drainage is the clogging of plastic endoprostheses. Therapeutic advances may be achieved by self-expanding or balloon-expandable braided or slit metal stents due to their large lumen and small surface area. Preliminary clinical studies show excellent early results but a divergent long-term clinical outcome depending on the selection of patients, the implantation technique or the type of the stent. If a long-distance overlap of biliary stenoses is achieved the metal stents may be superior to plastic prostheses due to a reduction of the risk of bile encrustation.

Bile Duct Neoplasms↗
PubMed1991

In vitro fragmentation of gallstones: comparison of electrohydraulic, electromagnetic and piezoelectric shockwave lithotripters.

To compare the fragmentation efficiency of three different shockwave systems, 63 human gallstone triplets were disintegrated in vitro using an electrohydraulic (MPL 9000, Dornier), an electromagnetic (Lithostar Plus, Siemens) and a piezoelectric (Piezolith 2300, R. Wolf) lithotripter. Since each stone triplet was obtained from the same gallbladder, the concrements of one such set were identical in physicochemical parameters. According to the maximal diameter, the calculi were divided into group A (6 to 15 mm) and group B (16 to 30 mm). Shockwave application was terminated when residual fragments measured 4 mm or less. Forty-five triplets were fragmented at energy settings mainly used in clinical treatment of patients with gallbladder stones (MPL 9000: 20 kV; Lithostar Plus: setting 9 (maximal); Piezolith 2300: setting 3). The fragmentation endpoint was achieved in group A (n = 3 x 36) with the Piezolith 2300 after median 150 (range = 50 to 500) pulses and with the Lithostar Plus after 150 (50 to 750) pulses compared with 500 (50 to 1,500) pulses using the MPL 9000 (p less than 0.01). In group B (n = 3 x 9) the Lithostar Plus (median = 750, range = 250 to 1,250 pluses) required fewer discharges than the Piezolith 2300 (1,250, 250 to 2,500 pulses; p less than 0.05) and the MPL (1,500, 500 to 1,600 [upper limit] pulses; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cholelithiasis↗
PubMed1991

Is ultrasonography a reliable method for evaluation of fragment clearance after biliary ESWL? A prospective, blinded study of two independent ultrasound units.

Ultrasound is the preceding method for evaluation of fragmentation and subsequent fragment clearance from the gallbladder. Considering the methodological shortcomings of ultrasonography, this study was therefore designed to investigate the degree of conformity between two independent ultrasound units. In our protocol patients were evaluated for fragments two weeks and three, six, nine and twelve months after ESWL. A restricted number of experienced sonographers in two independent ultrasound units examined the patient without knowledge of the other unit's findings. A total of 62 examinations have been carried out so far. Complete or sufficient conformity with a difference in size of 0-3mm was achieved in 24 examinations. Seven examinations revealed differences of 4-13 mm. In 31 cases the diagnosis of a stone-free gallbladder has been made, but only in 25 cases this could be confirmed by the other ultrasound unit. In six examinations a small fragment of less than 5mm was found by the respective other sonographer. We conclude that the diagnoses of a stone-free gallbladder after ESWL should be reconsidered by a second independent and experienced sonographer.

Adult↗
PubMed1990

[Focal size and shock wave pressure: a comparison of three different physical shock wave generators].

Shock-wave delivery and focal size of three different generators-electrohydraulic, electromagnetic and piezoelectric--were compared. Pressure measurements were uniformly made by needle hydrophone (piezoelectric transducer). The smallest focus, 17 x 3 x 3 mm, was achieved with the piezoelectric system (50% isobars), while the focus with the electromagnetic generator was much larger (50 x 7 x 4 mm). With the electrohydraulic generator the focal size of the 60% isobars was 20 mm in the longitudinal axis. The highest pressure, 1512 bar, was achieved with the piezoelectric lithotriptor (mean shock-wave pressure in focus: electrohydraulic 1000 + 100, electromagnetic 1000 + 25, piezoelectric 1400 + 27 bar). The rapid positive pressure rise was followed by a slower pressure fall and a small negative wave. In the focal region the negative pressure wave was between 112 and 200 bar with the electrohydraulic system, 100-146 bar with the electromagnetic one, and 134 bar with the piezoelectric one. The significance of the negative wave is not clear; perhaps it contributes to the development of the cavitation effect and facilitates stone fragmentation.

Electromagnetic Phenomena↗
PubMed1990

[Endoscopic and percutaneous implantation of self-expanding endoprostheses in biliary stenosis].

Self-expanding metal stents were implanted in 30 patients (14 men and 16 women, mean age 67 [40-86] years) with malignant (n = 27) or benign (n = 3) obstruction of the biliary tract (hepatic duct bifurcation: n = 14; choledochal duct: n = 16). The stents were introduced and left in place endoscopically in 13, percutaneously and transhepatically via a 7 or 9 F catheter in 17 patients. The stents, which expand to a diameter of 7-10 mm, in all cases achieved complete drainage, as confirmed by cholangiography. Jaundice completely disappeared in 28 of 30 patients. No complications were noted during a 30-day period of observation. After a median follow-up period of 90 days, 17 patients have been without jaundice for a median period of 141 (30-330) days. A recurrence of jaundice was noted in three patients (restenosis proximal to the stent in 2, incrustation with bile in one). Ten patients died, without any signs pointing to stent occlusion. These data indicate that the probability of stent patency in malignant stenoses of 200 days after implantation is 84%, so that stents in most cases provide a safe and effective means of drainage. Because they have a relatively large lumen with small surface area infection, occlusion and migration apparently occur less often than with conventional synthetic prostheses.

Adult↗
PubMed1990

[Electromagnetic shockwave lithotripsy of gallstones. Preliminary clinical experiences].

75 applications of extracorporeal electromagnetically produced shock-waves were performed on 40 patients with symptomatic gallbladder stones (27 women and 13 men; mean age 43.5 [25-69] years). The patients had up to three stones each, with a maximal diameter of 35 mm. Computed tomography revealed partial calcification of the stones in nine patients. Stone fragmentation succeeded in all patients. Two weeks after lithotripsy two patients were free of stone. Maximal fragment diameter, as measured by ultrasound, was less than 6 mm in 19 patients, 6-10 mm in 14, and 11-15 mm in five. At reexamination of 24 patients three months later, three additional patients were free of stone by ultrasound. No significant side effects were noted during the first 30 days after the procedure. But during further observation mild pancreatitis developed in two, while in one choledochal concrements caused obstructive jaundice which necessitated endoscopic papillotomy. These results demonstrate the effectiveness of this method of fragmenting gall-bladder stones.

Adult↗
PubMed1990

Unusual transcription termination of the ribosomal RNA genes in Ascaris lumbricoides.

We studied termination of transcription of the ribosomal RNA genes in Ascaris lumbricoides, the first representative in the phylum of nemathelminthes analysed so far. RNase protection experiments in vivo reveal that the 3' end of the precursor rRNA coincides with the end of mature 26S rRNA. Promoter-containing miniplasmids are able to direct unique 3' end formation in vitro at a site identical to that observed in vivo, whereas deletion of these sequences abolishes 3' end formation throughout the entire spacer. A nuclear run-on experiment in vitro confirms the drop of polymerase I concentration down-stream of this site. The termination site for polymerase I transcription of the rDNA operon in A. lumbricoides is therefore unique, and located at the very end of the 26S rRNA gene.

Animals↗
PubMed1990

The chloroplast psbK operon from mustard (Sinapis alba L.): multiple transcripts during seedling development and evidence for divergent overlapping transcription.

The mustard chloroplasts genes psbK and psbI are co-transcribed, giving rise to precursor transcripts of several size classes, which are processed to the monocistronic mature RNAs. The psbK and psbI coding regions are flanked by the two tRNA genes trnS-GCU and trnQ-UUG on the opposite DNA strand. Transcript mapping indicates that the (primary) psbK-psbI transcript overlaps the complete trnS-GCU and trnQ-UUG transcripts. The transcription start site of the psbK operon appears to overlap that of the rps16 gene. During seedling development, the psbK and psbI precursors and mature transcripts all become detectable between 30 and 48 h after sowing and then remain at constant levels without much difference either in light or in darkness.

Base Sequence↗