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Biomedical subjects

M Maier

Publications and source records attributed to M Maier.

At least 91 records · Page 5Linked to original sources
PubMed1998

A new HF current generator with automatically controlled system (Endocut mode) for endoscopic sphincterotomy--preliminary experience.

BACKGROUND AND STUDY AIMS: The main complications of endoscopic sphincterotomy are pancreatitis, hemorrhage, perforation and cholangitis. In a prospective randomized trial, a conventional current generator was compared to a new generator with an automatically controlled cut system (Endocut) for sphincterotomy. The purpose was to establish whether the new device reduces the complication rate of sphincterotomy. Our experiences over the last 2 years with the new HF current generator are described here. PATIENTS AND METHODS: In this study 100 patients were randomly assigned to one of the two generators. The following points were documented in a protocol form: abrupt or continuous cutting; length of papillotomy; complications. RESULTS: There were no significant differences in sex, age or indication for sphincterotomy. Nor were there any significant differences in the length of the sphincterotomy or mild pancreatitis. In contrast, an abrupt opening of the papillary roof was more frequently observed with the conventional generator (18 patients) than with the new device (one patient, P < 0.001). Mild bleeding occurred in two patients with the new unit, but in 13 with the conventional unit (P = 0.002). Moderate or severe bleeds were observed in neither of the two groups. During the subsequent application phase lasting for 2 years, the following complications occurred in a total number of 850 sphincterotomies (EST): pancreatitis 2.8% (one patient died); hemorrhages requiring transfusion 1% (n = 8); concealed perforations 0.3% (n = 3). CONCLUSIONS: According to our experience to date and based on this study, this new HF surgery unit enables performance of controlled, bloodless sphincterotomies. The danger of papillary hemorrhage appears to be reduced. All examiners found the new system to be safer and more convenient.

Electric Power Supplies↗
PubMed1998

Commonalities, conflicts and contradictions in organizational masculinities; exploring the gendered genesis of the Challenger disaster.

The events surrounding the 1986 decision to launch the Space Shuttle Challenger are reconstructed to illustrate how multiple masculinities, particularly between and among managers and engineers, contributed to that organizational crisis. An analysis of gendered power relations--especially among men--reveals how the construction of particular forms of "masculinities," and the ways in which they are reproduced, rationalized or resisted, vary as a result of contextual changes. Commonalities and differences among these masculinities are discussed. We close by exploring possible contradictions in the construction of organizational masculinities and their implications for organizational practice.

Accidents, Aviation↗
PubMed1998

[Physical parameters of extracorporeal shock waves].

Prerequisites for the successful investigation of the mechanism of action of ESWT (extracorporeal shockwave therapy) and the establishment of treatment standards, are the ability to measure, and a knowledge of, the physical parameters involved. The most accurate measurements are obtained with laser hydrophones. Various parameters (amplitude, rise time, pulse width, pressure pulse decay, rarification phase) of a typical shock wave can thus be determined. These can then be used to calculate energy flux density, focal extent, focal volume and as well as focal energy, effective energy in a defined area, and effective biological energy. These parameters can be utilized to work out a theoretical treatment protocol.

Equipment Safety↗
PubMed1997

Efficient downstream processing of maltodextrin phosphorylase from Escherichia coli and stabilization of the enzyme by immobilization onto hydroxyapatite.

Downstream processing by biospecific chromatography of maltodextrin phosphorylase from Escherichia coli, overexpressed in E. coli, was substantially improved by a novel approach using ceramic hydroxyapatite. Wild-type and a less active mutant enzyme were purified from crude bacterial cell extracts in one efficient separation step that yielded phosphorylase in purity > 95% in at least 90% recoveries. At pH 6.9 and 25 degrees C, wild-type and mutant phosphorylases eluted from the hydroxyapatite column at a phosphate concentration of 0.4 M whereas calcium ions failed to displace the enzymes. The dynamic capacity for phosphorylase binding in the presence of bulk proteins was approximately 3 mg enzyme ml-1 matrix. The interaction of E. coli phosphorylase with hydroxyapatite seems to be mediated by surface amino groups, so that the bound enzyme retained almost full catalytic activity. Compared to the soluble enzyme, immobilization onto hydroxyapatite resulted in a more than 30-fold stabilization of wild-type phosphorylase against thermal and proteolytic inactivation and thus could improve the operational stability of phosphorylase during conversion of polysaccharide to glucose 1-phosphate.

Chromatography↗
PubMed1997

Cationic Polystyrene Nanoparticles: Preparation and Characterization of a Model Drug Carrier System for Antisense Oligonucleotides

Polystyrene nanoparticles were prepared by surfactant-free emulsion polymerization using water-soluble cationic initiators to induce a positive surface charge. Reaction conditions were optimized to obtain monodisperse polymeric particles with mean diameters of 150-200 nm. The nanospheres were characterized by scanning electron microscopy, photocorrelation spectroscopy, conductometric titrations, zeta potential measurements, and investigations of their colloidal stability in different media. Sterically stabilized polymeric latexes, showing a low cytotoxicity in the concentrations required for antisense experiments, are capable of binding negatively charged oligonucleotides. The influence of pH, type of latex, and oligonucleotide modification on the adsorption characteristics was investigated. The results indicate that high attractive forces in terms of multiple electrostatic interactions are predominantly responsible for oligonucleotide binding. Comparing the experimental data with calculations based on the random sequential adsorption (RSA) model, it appears that the surface coverage at the saturation level can be considered as a monolayer of "side-on" adsorbed molecules. Oligonucleotide release can be induced by the addition of anionic surfactants or by increasing the pH of the dispersion medium. Investigations of the enzymatic degradation by micellar electrokinetic capillary chromatography (MECC) indicate a significantly enhanced stability of adsorbed oligonucleotides against nuclease attack. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗
PubMed1997

[Percutaneous and transpapillary laser lithotripsy of intrahepatic gallstones].

PROBLEM AND OBJECTIVE: In the last few years several intra- and extracorporeal endoscopic methods have been developed for treating intrahepatic gallstones, but as yet no ideal instrumentation has been found. This study was undertaken to test the efficacy and possible complications of intracorporeal laser lithotripsy for intrahepatic gallstones. PATIENTS AND METHODS: 16 consecutive patients were included (13 women and 3 men, median age 64 [28-82] years) with intrahepatic biliary tract stones which could not be removed by conventional endoscopy. A rhodamine-6G-laser with an integrated stone recognition system was used. The glass fibres of the laser instrument were introduced perorally or percutaneously and placed at the stone. RESULTS: The percutaneous procedure under cholangioscopic control succeeded in four of the patients, while 12 were treated by a transpapillary approach (two under fluoroscopic, ten under cholangioscopic control). In eight of the latter group all stones were completely fragmented, i.e. 12 of the total were successfully treated. Of the remaining four patients two were cleared of stone by additional measures (extracorporeal shockwave lithotripsy and electrohydraulic lithotripsy, respectively), two were treated pallatively by endoprosthesis. One patient developed an acute cholangitis which was successfully treated with antibiotics and biliary drainage. There were no deaths. CONCLUSIONS: Particularly when performed transcutaneously, laser lithotripsy provides effective treatment of intrahepatic gall stones. Cholangioscopic monitoring, to place the glass fibre at the stone, is usually required in the transpapillary approach.

Adult↗
PubMed1997

Cure with omeprazole plus amoxicillin versus long-term ranitidine therapy in Helicobacter pylori-associated peptic ulcer bleeding.

BACKGROUND: Long-term prophylaxis with ranitidine reduces the risk of recurrent bleeding in patients with a history of bleeding peptic ulcers. To date, no randomized study has been performed to compare cure of Helicobacter pylori infection versus H2 blocker prophylaxis in patients with bleeding peptic ulcer. METHODS: In a prospective randomized study, 95 consecutive patients with H. pylori-associated peptic ulcer bleeding were randomized to either ranitidine prophylaxis (150 mg at night) for 2 years or to H. pylori-eradication with omeprazole 60 mg twice daily plus amoxicillin 750 mg three times daily for 10 days. RESULTS: (Intention-to-treat analysis). Forty-eight patients were enrolled in the ranitidine group; 47 in the omeprazole-plus-amoxicillin group. Mean follow-up was 576 days (77 to 730). Ulcer recurrence rate was 31.3% in the ranitidine group (group 1) versus 6.37% in the eradication group (group 2; p = 0.0018). More patients had recurrent bleeding in group 1 (8.3%) than in group 2 (4.2%) but we were not able to show a statistically significant difference with respect to recurrent bleeding between groups (p = 0.29). Definite cure of H. pylori infection was achieved in 89.3%. CONCLUSIONS: Cure of H. pylori infection reduces recurrence of peptic ulcer and therefore rebleeding more effectively than does long-term maintenance therapy with an H2 blocker.

Adult↗
PubMed1997

Exposure to alcohol in utero blunts splenic sympathetic neural response to endotoxin and interleukin-1beta in the rat.

Systemic administration of endotoxin (LPS) or interleukin-1beta (IL-1) to prepubertal rats induced a marked increase in splenic but not cardiac norepinephrine (NE) turnover, an index of sympathetic neural activity. In contrast, the splenic neural response was blunted in their fetal alcohol-exposed (FAE) cohorts. Because the sympathetic outflow to lymphoid organs is considered an important immune modulator, the anomalous neural response to immune signals may partly account for the impaired cellular immunity and, thus, for the increased susceptibility to infections associated with FAE.

Adrenocorticotropic Hormone↗
PubMed1997

Acute ulcer bleeding. A prospective randomized trial to compare Doppler and Forrest classifications in endoscopic diagnosis and therapy.

The aim of our prospective randomized study involving 100 patients was to investigate whether Doppler ultrasound can be used to select patients at risk for ulcer rebleeding. Ulcers in the Forrest group classified as having a visible vessel or a clot were treated prophylactically by injection with epinephrine solution. In the Doppler group, in contrast, only ulcers with a positive Doppler signal were treated endoscopically. In the Doppler group, rebleeds occurred significantly less frequently (2%, P < 0.03) than in the Forrest group (14%). Emergency surgery was only necessary in the Forrest group (0% vs 5%; P = 0.02). Bleeding-related mortality was 0% and 4% (P = 0.15) and the overall mortality 0% and 10% (P = 0.02), in the Doppler and Forrest groups, respectively. These results appear to show that Doppler-based injection treatment is superior to endoscopic treatment based exclusively on the Forrest classification. In our study, Doppler-based local endoscopic treatment reduced the danger of a rebleed and thus the number of emergency operations and the overall mortality.

Acute Disease↗
PubMed1997

Arthralgia as an early extraintestinal symptom of Whipple's disease. Report of five cases.

Five patients with Whipple's disease all suffered from arthralgia for a long time (15 years in one case) before developing gastrointestinal or other symptoms. In all patients, arthralgia was seronegative, and there was no evidence of joint destruction. Arthralgias were symmetric and migrating. Whipple's disease is part of the differential diagnosis of enteropathic arthralgia. Thereby, the polymerase chain reaction can be a helpful tool to prove Whipple's disease in difficult differential diagnosis.

Arthralgia↗
PubMed1997

Fluoroscopically guided laser lithotripsy versus extracorporeal shock wave lithotripsy for retained bile duct stones: a prospective randomised study.

BACKGROUND AND AIMS: To compare extracorporeal shock wave lithotripsy (ESWL) and laser induced shock wave lithotripsy (LISL) of retained bile duct stones to stone free rate, number of therapeutic sessions, and costs. PATIENTS: Thirty four patients were randomly assigned to either ESWL or LISL therapy. The main reasons for failure of standard endoscopy were due to stone impaction (n = 12), biliary stricture (n = 8), or large stone diameter (n = 14). METHODS: An extracorporeal piezoelectic lithotripter with ultrasonic guidance and a rhodamine 6G laser with an integrated stone tissue detection system were used. LISL was performed exclusively under radiological control. RESULTS: Using the initial methods complete stone fragmentation was achieved in nine of 17 patients (52.4%) of the ESWL group and in 14 of 17 patients (82.4%) in the LISL group, or combined with additional fragmentation techniques 31 of the 34 patients (91.2%) were stone free at the end of treatment. In comparison LISL tended to be more efficient in clearing the bile ducts (p = 0.07, NS). Significantly less fragmentation sessions (1.29 v 2.82; p = 0.0001) and less additional endoscopic sessions (0.65 v 1.6; p = 0.002) were necessary in the LISL group. There were no major complications in either procedure. CONCLUSIONS: Compared with ESWL, fluoroscopically guided LISL achieves stone disintegration more rapidly and with significantly less treatment sessions, which leads to a significant reduction in cost.

Adult↗
PubMed1996

[Severe complications in diagnostic laparoscopy. 9 years experience in 747 examinations].

BACKGROUND: Despite the introduction of non-invasive imaging procedures, diagnostic laparoscopy is still indicated in suspected liver cirrhoses, cancer staging and ascites or fever of unknown origin. Although the use of laparoscopy decreased over the last decade, some centers still have much experience and their complication rates are of special interest. PATIENTS AND METHODS: The complication rate of 747 patients undergoing a diagnostic laparoscopy in our clinic during the last 9 years is listed retrospectively, and the respective therapy is examined. RESULTS: Severe complications were found in 11 cases (1.5%): 6 bleeding complications, 2 bowel perforations and 3 other complications. Five of these 11 patients had to be operated on (45%). One patient with metastatic gastric cancer died of a multiple organic failure following a lararoscopic tumor biopsy (0.13%). CONCLUSION: The diagnostic laparoscopy is of significant value and has still a low complication-rate in centers with special experience.

Abdominal Neoplasms↗
PubMed1996

Hippocampal age-related changes in schizophrenia: a proton magnetic resonance spectroscopy study.

We have used proton magnetic resonance spectroscopy to study in vivo N-acetyl aspartate (NAA), choline and creatine in the hippocampi of 26 schizophrenics and 38 normal controls. Measurements of NAA suggest that age-related neuronal loss occurs at a similar rate in schizophrenics and controls. On the other hand, we observe in schizophrenics age-related choline abnormalities not present in controls. We suggest that these age-related changes may be related to an abnormal myelination process and contribute to the observed clinical deterioration associated with schizophrenia.

Adolescent↗
PubMed1996

The rabbit ileal lipid-binding protein. Gene cloning and functional expression of the recombinant protein.

A bile-acid-binding protein of Mr 14000 has been previously identified by photoaffinity labeling in rabbit ileal brush border membrane vesicles [Kramer et al. (1993) J. Biol. Chem. 268, 18035-18046]. This peripheral membrane-associated protein was purified and identified as an ileal lipid-binding protein. It was further shown to be identical to the cytosolic 14-kDa bile-acid-binding protein from the same tissue. Starting with sequence information from tryptic fragments, we cloned and sequenced the gene and its transcript. It has four exons (123, 176, 90, 115 bp) and three introns (1372, 2291, 3137 bp) and a similar structure as the genes from other members of the fatty-acid-binding protein family. The deduced protein has 128 amino acid residues and a calculated molecular mass of 14404 Da. It exhibits high similarity to its human (83%), mouse (77%), rat (76%) and porcine (72%) counterparts. Furthermore, the recombinant protein was produced in Escherichia coli and shown to be identical to native protein from ileal tissue. Functionality of the recombinant protein was demonstrated by labeling with various photoaffinity derivatives of bile acids. Ranking of the photolabeling efficiency of these probes towards the recombinant protein was comparable to the respective ranking towards the native protein. Polyclonal antibodies that were raised in hens against the recombinant protein, specifically recognized the ileal lipid-binding protein in the brush border membrane and cytosol from rabbit ileum. In contrast, no labeling was observed with jejunal tissue. Our results suggest a specific role of the membrane-associated ileal lipid-binding protein for the process of ileal bile acid uptake.

Affinity Labels↗
PubMed1996

Regulation of human heart contractility by essential myosin light chain isoforms.

Most of the patients with congenital heart diseases express the atrial myosin light chain 1 (ALC-1) in the right ventricle. We investigated the functional consequences of ALC-1 expression on the myosin cycling kinetics in the intact sarcomeric structure using multicellular demembranated fibers ("skinned fibers") from the right ventricular infundibulum of patients with Tetralogy of Fallot (TOF), double outlet right ventricle (DORV), and infundibular pulmonary stenosis (IPS), Force-velocity relation was analyzed by the constant-load technique at maximal Ca2+ activation (pCa 4.5). Half-time of tension development (t1/2) was investigated by monitoring contraction initiation upon photolytic release of ATP from caged-ATP in rigor. The patients investigated here expressed between 0 and 27% ALC-1. There was a statistically significant correlation between ALC-l and maximal shortening velocity (Vmax) which rose 1.87-fold from 1.2 muscle length per second (ML/s) to 2.25 ML/s in a normal (0% ALC-1) and diseased (19.9% ALC-1) ventricle. Half-time of tension development decreased 1.85-fold with increasing ALC-1 expression (t1/2) was 0.252 s and 0.136 s at 2 and 18.4% ALC-1, respectively). We conclude that the expression of ALC-1 in the human heart modulates cross-bridge cycling kinetics accelerating shortening velocity and isometric tension production.

Adenosine Triphosphate↗