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Biomedical subjects

L Greiner

Publications and source records attributed to L Greiner.

At least 19 recordsLinked to original sources
PubMed2002

Lambda spectra in 11.6A GeV/c Au-Au collisions.

E896 has measured Lambda production in 11.6A GeV/c Au-Au collisions over virtually the whole rapidity phase space. The midrapidity p(t) distributions have been measured for the first time at this energy and appear to indicate that the Lambda hyperons have different freeze-out conditions than protons. A comparison with the relativistic quantum molecular dynamics model shows that while there is good shape agreement at high rapidity the model predicts significantly different slopes of the m(t) spectra at midrapidity. The data, where overlap occurs, are consistent with previously reported measurements.

Journal Article↗
PubMed2001

Why do bilioduodenal plastic stents become occluded? A clinical and pathological investigation on 100 consecutive patients.

BACKGROUND AND STUDY AIMS: The main complication associated with biliary stenting is stent occlusion. This study tested the hypothesis that bilioduodenal reflux may play a crucial role in stent clogging. PATIENTS AND METHODS: Plastic stents in 100 consecutive patients with various biliary disorders were investigated macroscopically and cytologically. RESULTS: In 37 patients with elective stent extraction, the only risk factor for stent occlusion was the duration of stenting. Plant material was found as a consequence of duodenobiliary reflux in 38 of the 89 stents with any stent content. In patients who had two stents, the stent content was identical in eight of 14 cases. CONCLUSIONS: In addition to other mechanisms of biliary stent occlusion, duodenobiliary reflux appears to play an important role. A stent design capable of at least partly preventing this type of reflux might be of clinical benefit.

Adult↗
PubMed2001

Long-term results after successful extracorporeal gallstone lithotripsy: outcome of the first 120 stone-free patients.

BACKGROUND: Long-term results after successful extracorporeal shock wave lithotripsy (ESWL) of symptomatic gallbladder stones are determined by stone and complaint recurrence. The long-term outcomes of the first successfully treated patients of our Department are presented. METHODS: The first consecutive 120 patients with symptomatic gallbladder stones who became stone-free after ESWL plus oral bile acids in the years 1986 and 1987 were included in this study. They were followed up at 1-to 2-year intervals clinically and by ultrasonography until April 1998. Recurrence of stones and biliary symptoms and subsequent treatment were recorded. The effect of various factors on recurrence was analyzed. RESULTS: Median follow-up time was 6.0 years for all patients and 8.8 years for patients without recurrence (range, 0-11.2 years for both). Actuarial recurrence probability was 1.9%-16.6% per year reaching 60.2% (49.9%, 70.3%) (95% confidence interval) after 10 years. Patients with stone recurrence revealed significantly more stones before ESWL than patients without recurrence (P < 0.03). Other factors were not significantly different. The majority of stone recurrences were symptomatic requiring retreatment, mostly cholecystectomy. CONCLUSION: The probability of gallbladder stone recurrence after successful ESWL remains high during a decade of follow-up. Many patients require repeated nonsurgical treatment or cholecystectomy. Thus long-term results are unsatisfactory and ESWL should be offered only exceptionally.

Adult↗
PubMed2000

Benzoylformate decarboxylase from Pseudomonas putida as stable catalyst for the synthesis of chiral 2-hydroxy ketones.

The thiamin diphosphate- and Mg2+-dependent enzyme benzoylformate decarboxylase (BFD) from Pseudomonas putida was characterized with respect to its suitability to catalyze the formation of chiral 2-hydroxy ketones in a benzoin-condensation type reaction. Carboligation constitutes a side reaction of BFD, whereas the predominant physiological task of the enzyme is the non-oxidative decarboxylation of benzoylformate. For this purpose the enzyme was obtained in sufficient purity from Pseudomonas putida cells in a one-step purification using anion-exchange chromatography. To facilitate the access to pure BFD for kinetical studies, stability investigations, and synthetical applications, the coding gene was cloned into a vector allowing the expression of a hexahistidine fusion protein. The recombinant enzyme shows distinct activity maxima for the decarboxylation and the carboligation beside a pronounced stability in a broad pH and temperature range. The enzyme accepts a wide range of donor aldehyde substrates which are ligated to acetaldehyde as an acceptor in mostly high optical purities. The enantioselectivity of the carboligation was found to be a function of the reaction temperature, the substitution pattern of the donor aldehyde and, most significantly, of the concentration of the donor aldehyde substrate. Our data are consistent with a mechanistical model based on the X-ray crystallographic data of BFD. Furthermore we present a simple way to increase the enantiomeric excess of (S)-2-hydroxy-1-phenyl-propanone from 90% to 95% by skillful choice of the reaction parameters. Enzymatic synthesis with BFD are performed best in a continuously operated enzyme membrane reactor. Thus, we have established a new enzyme tool comprising a vast applicability for stereoselective synthesis.

Amino Acid Sequence↗
PubMed2000

[The liver and hereditary hemorrhagic telangiectasia].

Hereditary hemorrhagic teleangiectasia, or Rendu-Osler-Weber syndrome, is an autosomal dominant inherited disease characterized by vascular derangement in many organs. The vascular derangement includes teleangiectases, arteriovenous fistulas and aneurysms. Liver involvement in hereditary hemorrhagic teleangiectasia is a rare and sometimes severe disease which was unknown and mostly detected at autopsy until a few decades ago. Typical findings are vascular malformations and connective tissue formation with fibrosis and atypical cirrhosis. In the last years we observed five Osler patients with exclusive or prevailing involvement of the liver. An unambiguous diagnosis can be ascertained by means of a hazardous liver puncture with typical histological findings. Angiography allows a reliable identification of even minor vascular deformities. The present study was undertaken to demonstrate the courses of disease, the techniques of examination and the therapeutical options of this rare manifestation of Osler-disease. In every case one could observe hepatic malformations which were established as typical Osler findings with the assistance of histological and above all sonographical/color-Doppler-sonographical devices. These special sonographic/color-Doppler-sonographic features make it possible to give up the histological diagnostics or exhaustive investigations by means of angiography, computer-tomography or MRI.

Angiography↗
PubMed2000

[Dilatation of pancreatic duct stenoses with the ring coagulator--initial experiences].

Stenoses of the main pancreatic duct in chronic pancreatitis should be treated by interventional endoscopy. If mechanical dilatation was unsuccessful, a thermodilator has been in use in our clinic since September 1998. From September 1998 to March 1999 dilation of pancreatic duct stenoses was done by the thermodilator in six patients. An asymptomatic elevation of amylase and lipase was noticed in one patient. There were no further complications. The termodilator is a promising instrument for dilatation of difficult stenoses of the main pancreatic duct. Before general use, however, evaluation of the success and complication rates in a greater number of patients is needed.

Adult↗
PubMed1999

[The holmium-YAG laser: a suitable instrument for stone fragmentation in choledocholithiasis. The assessment of the results of its use under babyscopic control].

BACKGROUND AND OBJECTIVE: Stone fragmentation is required in ca. 5% of patients with choledocholithiasis to free the patients of stones. Several extra- and intracorporal methods of stone fragmentation (lithotripsy) have been available. We here report our experience with the recently available holmium-YAG laser, used under babyscopic monitoring. PATIENTS AND METHODS: Between September 1997 and May 1998 lithotripsy was performed by holmium-YAG laser under monitoring in 20 patients with choledocholithiasis in whom conventional methods had failed to achieve stone fragmentation. RESULTS: All stones were cleared in 19 of the 20 patients. A second session was necessary in four patients, three sessions in one. There was no serious complication and no death during a 30-day follow-up. CONCLUSION: Holmium-YAG laser lithotripsy under babyscopic monitoring has been shown to be a suitable method in patients with choledocholithiasis in whom previous treatment has failed it is complementary to current methods of stone fragmentation.

Aged↗
PubMed1999

The thermodilator: an effective instrument in the palliative therapy concept of malignant bile duct stenosis.

BACKGROUND AND METHODS: In the case of incurable malignant bile duct stenosis the aim of therapy is to secure the bile flow. Sometimes dilation of the stenosis is necessary to enable the introduction of a biliary duodenal stent or the replacement of a small-bore stent by a large-bore one. The previously most commonly used methods - bougienage and balloon dilation - can be unsuccessful with severe stenoses, which means that an extension of the endoscopic therapeutic instrumentarium is desirable. We examined the success rates and complications of a thermodilator which can be used to dilate bile duct stenoses. RESULTS AND CONCLUSIONS: In 21 out of 24 applications the therapeutic objective was achieved. In one case we observed an endoscopically controllable bile duct hemorrhage. The thermodilator is therefore a valuable addition to the endoscopic treatment possibilities of malignant bile duct stenosis.

Aged↗
PubMed1999

The liver in hereditary hemorrhagic telangiectasia (Weber-Rendu-Osler disease).

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT, Osler disease) is an inborn error in the structure of different vessels. This leads to vascular malformations in multiple organ systems. In the liver vascular abnormalities are associated with a marked fibrosis and/or cirrhosis. METHODS AND RESULTS: We found hepatic manifestation of Osler disease in four women and one man (51-63 years old) presenting initially with slight disturbances of liver function. In three patients progressive liver insufficiency developed. The characteristic histologic and sonographic findings are described and discussed. CONCLUSION: Ultrasonography with color and Doppler analysis is diagnostic, replacing more extensive procedures like angiography, computer tomography, or magnetic resonance tomography.

Aged↗
PubMed1998

[Clinical value of endoscopic ultrasound-guided transesophageal fine needle puncture of mediastinal lesions].

BACKGROUND AND OBJECTIVE: As the mediastinum has been a region difficult to access for biopsy, mediastinoscopy has been required in most cases. In a prospective study the value of transoesophageal endoscopic ultrasound (TEUS) guided aspiration biopsy was assessed as an alternative. PATIENTS AND METHODS: TEUS-guided fine-needle aspirations were performed between May 1995 and March 1998 in 35 patients with mediastinal space-occupying lesions. In all cases the conventional endoscopic method or percutaneous puncture-sonography had been impossible or had failed. In one patient it had been performed after a negative mediastinoscopy. RESULTS: In 34 patients (97%) the aspirated tissue cylinder could be evaluated histologically. There were no complications. Malignancy was demonstrated in 24 patients, and there were one case each of sarcoidosis, silicoanthracosis and two cases of retrosternal goitre. In four of seven patients the negative preoperative diagnosis was confirmed at operation or by follow-up. There were two false-negative results and in one patient there has been no definitive diagnosis. The accuracy of the method was thus 91.4%, the positive predictive value for malignancy 88.9% and the negative predictive value for malignancy 72.7%. Ultrasound alone was a poor predictor of malignancy in lymph node enlargement. CONCLUSION: TEUS-guided fine-needle aspiration of space-occupying mediastinal lesions is an effective and low-risk method that can in selected cases shorten the diagnostic process and avoid methods that are expensive or lead to complications such as transpulmonary biopsy guided by computed tomography or mediastinoscopy.

Adult↗
PubMed1997

[Transcutaneous sonography of the gastroesophageal junction in prospective comparison with endoscopy].

BACKGROUND AND OBJECTIVE: Despite its practical value, few data exist on assessing the gastrooesophageal junction by transcutaneous sonography (TS). A prospective study was undertaken to compare TS and endoscopy (ES) of this region. PATIENTS AND METHODS: Between 1 September, 1994 and 31 May, 1995 TS of the lower oesophagus was followed by ES of this region in 211 patients (116 women, 95 men; mean age 58.9 [14-90] years). None had previously been examined by ES or radiological contrast study of the oesophagus and stomach. Endoscopist and sonographer were blinded to each other's findings. The ability to visualize the abdominal oesophagus by TS and to recognize abnormalities were compared with ES results, both quantitatively and descriptively. RESULTS: The diaphragmatic course of the terminal oesophagus or (where present) a gastric hernia were well visualized by TS in all 211 patients. In 78 patients with normal results on TS and ES the visible length of the oesophagus was 3.3 +/- 0.8 cm, with a wall thickness of 4.5 +/- 1.0 mm (mean +/- standard deviation). In seven of eight patients with echo-poor wall thickness between 9 and 27 mm, suspected of being malignant, ES revealed neoplasm of the terminal oesophagus or cardia (six T2 to T4 carcinomas; one MALT lymphoma). One patient had involvement of the oesophagus and cardia as part of Crohn's disease. No case of malignancy remained unrecognized by ES. 64 of 77 hiatal hernias diagnosed by ES were also recognized by TS. Hiatal hernia was falsely diagnosed by TS in four patients. Oesophageal varices were correctly identified by TS in three of eight patients, as was one case of achalasia. CONCLUSION: Transcutaneous sonography is a good screening method with a high sensitivity for changes in wall architecture and it provides indications for further selective diagnostic procedures.

Adolescent↗