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Biomedical subjects

D Schubert

Publications and source records attributed to D Schubert.

At least 19 recordsLinked to original sources
PubMed2006

[Endoscopic treatment of mediastinal anastomotic leaks].

BACKGROUND: Surgery, as well as conservative treatment, in patients with clinically apparent intrathoracic anastomotic leaks are often associated with poor results and carry a high morbidity and mortality. This report describes our results with the endoscopic treatment of intrathoracic anastomotic leakages. PATIENTS: 27 consecutive patients presenting with clinically apparent intrathoracic anastomotic leak, caused by resection of an epiphrenic diverticulum (n=1), esophagectomy for esophageal cancer (n=19), limited resection for carcinoma of the gastroesophageal junction (n=1) or gastrectomy for gastric cancer (n=6) were endoscopically treated. The extent of the dehiscences ranged from about 10-70%. After endoscopic lavage and debridement of the leakage (mean duration: 16,8 days) the leaks were closed with fibrin clue (n=9) or endoclips (n=2) in cases of smaller leaks or by stent placement (n=11), stent placement after unsuccessful fibrin clue injections (n=3) or stent placement and endoclipping (n=1) in patients with a large leakage. Simultaneously the periesophageal mediastinum was drained by chest drains. RESULTS: 25 of 27 patients were successfully treated endoscopically. Under endoscopic treatment one patient died due to septic multiorgan failure. Another patient developed a refractory, persistent leak. Procedure related complications (stent migration, anastomotic stenosis) were obtained in 6 patients. CONCLUSION: An endoscopic approach is successful and safe to treat symptomatic intrathoracic anastomotic leaks smaller than 70% of the circumference. An endoscopic lavage and debridement of the leak, prior to leak closure, seems to be helpful to reduce mediastinal and pleural inflammation. In patients with smaller leaks (<30%) fibrin clue injections and endoclipping is recommended. Patients with a dehiscence from 30-70% of the circumference profit from stent placement.

Adult↗
PubMed2005

Morphology, electrophysiology and functional input connectivity of pyramidal neurons characterizes a genuine layer va in the primary somatosensory cortex.

Cortical layer V classically has been subdivided into sublayers Va and Vb on cytoarchitectonic grounds. In the analysis of cortical microcircuits, however, layer Va has largely been ignored. The purpose of this study was to investigate pyramidal neurons of layer Va in view of their potential role in integrating information from lemniscal and paralemniscal sources. For this we combined detailed electrophysiological and morphological characterization with mapping of intracortical functional connectivity by caged glutamate photolysis in layer Va of rat barrel cortex in vitro. Electrophysiological characterization revealed pyramidal cells of the regular spiking as well as the intrinsically burst firing type. However, all layer Va pyramidal neurons displayed uniform morphological properties and comparable functional input connectivity patterns. They received most of their excitatory and inhibitory inputs from intracolumnar sources, especially from layer Va itself, but also from layer IV. Those two layers were also the main origin for transcolumnar excitatory inputs. Layer Va pyramidal neurons thus may predominantly integrate information intralaminarly as well as from layer IV. The functional connectivity maps clearly distinguish layer Va from layer Vb pyramidal cells, and suggest that layer Va plays a unique role in intracortical processing of sensory information.

Animals↗
PubMed2005

CoCoDat: a database system for organizing and selecting quantitative data on single neurons and neuronal microcircuitry.

We present a novel database system for organizing and selecting quantitative experimental data on single neurons and neuronal microcircuitry that has proven useful for reference-keeping, experimental planning and computational modelling. Building on our previous experience with large neuroscientific databases, the system takes into account the diversity and method-dependence of single cell and microcircuitry data and provides tools for entering and retrieving published data without a priori interpretation or summarizing. Data representation is based on the framework suggested by biophysical theory and enables flexible combinations of data on membrane conductances, ionic and synaptic currents, morphology, connectivity and firing patterns. Innovative tools have been implemented for data retrieval with optional relaxation of search criteria along the conceptual dimensions of brain region, cortical layer, cell type and subcellular compartment. The relaxation procedures help to overcome the traditional trade-off between exact, non-interpreted data representation in the original nomenclature and convenient data retrieval. We demonstrate the use of these tools for the construction, tuning and validation of a multicompartmental model of a layer V pyramidal cell from the rat barrel cortex. CoCoDat is freely available at . Its application is scalable from offline use by individual researchers via local laboratory networks to a federation of distributed web sites in platform-independent XML format using Axiope tools.

Action Potentials↗
PubMed2005

[Ropivacain after inguinal hernia surgery. A prospective, randomised, double-blinded, controlled study].

BACKGROUND: To optimise the satisfaction of patients after repair of primary inguinal hernias under local anaesthesia, we analysed the analgetic power of Ropivacain in the postoperative period. MATERIAL AND METHODS: One hundred consecutive patients underwent repair under local anaesthesia with the same volume of 0.75% Ropivacain or 1% Mepivacain in a randomised and blinded manner. Postoperative pain analysis was carried out in all patients. RESULTS: Subjective pain levels at rest and under stress as well as impairment by pain were found to be significantly lower in the Ropivacain group at the day of operation. Decrease in vital capacity and peak flow showed similar results. The postoperative amount of analgesics and time of mobilisation showed a positive influence by the use of Ropivacain. CONCLUSION: Ropivacain reduces postoperative pain levels after hernia repair. This leads to increased comfort for patients, without elevated perioperative risk.

Adult↗
PubMed2005

Laparoscopic-endoscopic rendezvous resection of upper gastrointestinal tumors.

BACKGROUND: Endoscopic and laparoscopic local resection of gastric tumors has increasingly been performed in recent years. This article describes the technical considerations and early results of laparoscopic-endoscopic rendezvous resection of gastric lesions. PATIENTS AND METHODS: Rendezvous resection was performed in 26 patients with submucosal gastric tumors (n = 22) and early gastric cancer (n = 4). Laparoscopic wedge resection (LWR) was performed in 16 patients with anterior wall tumors and laparoscopic intragastric resection (LIR) in 7 patients with posterior wall tumors. Conversion to open surgery was carried out in 3 cases. RESULTS: Operation times were 53 min (range 35-115) for LWR and 83 min (range 56-130) for LIR, respectively. In submucosal lesions the mean tumor size was 36 mm (range 16-47) and in early gastric cancer 17.3 mm (range 16-20). Rendezvous resection was performed with curative intent and clear resection margins in all patients without lymphatic or vessel permeation. Postoperative complications occurred in 2 patients. After a mean follow-up of 22.8 months (range 2-71), no local recurrence or metastatic disease and no tumor-related death were observed. CONCLUSIONS: When selected properly, the laparoscopic-endoscopic approach is considered to be curative and safe for resection of localized gastric tumors.

Endoscopy, Gastrointestinal↗
PubMed2005

Oncologic surgery: the advantages and disadvantages of minimally invasive surgery.

For the last 15 years, the minimalized traumatization of laparoscopic surgical procedures has changed the treatment of numerous diseases. As a result, the method has also become an interesting therapeutic alternative for oncological indications, too. Nevertheless, its use in the special field of oncology, in particular when applied in curative intent, continues to give rise to controversial discussion. This paper takes a look at the potential advantages and disadvantages of the laparoscopic modality with regard to immune function and staging laparoscopy. In view of the fact that, at the present time, curative resections are being carried out in relevant numbers, in particular in the field of colorectal surgery, the technical feasibility, oncological radicality and oncological long-term outcomes are discussed on the basis of the data reported in the relevant literature on laparoscopic colorectal surgery.

Humans↗
PubMed2004

Impact of taurolidine on the growth of CC531 coloncarcinoma cells in vitro and in a laparoscopic animal model in rats.

BACKGROUND: The object of this study was to examine the effect of taurolidine on intraabdominal tumor growth in a laparoscopic animal model. We tested the cytotoxic, antiadhesive, and anti-invasive effects of this substance on CC531 adenocarcinoma cells in vitro and in vivo using WAG rats. METHODS: For in vitro experiments, Transwell dual chambers with polycarbonate filters coated with 100 microg/cm2 Matrigel were used to investigate the effects of 5, 10, and 20 microl of 2.0% taurolidine on the invasion of 1 x 10(5) CC531 adenocarcinoma cells. For the adhesion assays, tumor cells were applied onto microtiter plates coated with 5, 10, and 20 microl taurolidine and 0.9% NaCl solution for the control group subsequently. For in vivo experiments, 40 WAG rats were randomized into three therapy groups and one control group. All animals underwent laparoscopy and received 1 ml of CC531 adenocarcinoma cells (5 x 10(6) cells/ml) intraabdominally at the beginning of the procedure. According to the randomization, the rats were administered taurolidine with different concentrations or 1 ml of 0.9% NaCl solution for the control group. After 21 days, the animals were killed and the intraabdominal tumor weight was determined. RESULTS: For the in vitro experiments, we found a moderate cytotoxicity and a significant inhibition of tumor cell adhesion and invasion (p < 0.01) by all taurolidine concentrations used in the assay. For in vivo experiments, the application of all concentrations of taurolidine significantly decreased the intraperitoneal tumor weight (p < 0.001). CONCLUSION: Taurolidine significantly decreases adhesion and invasion of CC531 adenocarcinoma cells in vitro and significantly diminishes tumor growth in vivo. This may offer additional therapeutic options for laparoscopic surgery for colorectal cancer.

Adenocarcinoma↗
PubMed2004

Projection structure and oligomeric state of the osmoregulated sodium/glycine betaine symporter BetP of Corynebacterium glutamicum.

The high-affinity glycine betaine uptake system BetP, an osmosensing and osmoregulated sodium-coupled symporter from Corynebacterium glutamicum, was overexpressed in Escherichia coli with an N-terminal StrepII-tag, solubilized in beta-dodecylmaltoside and purified by streptactin affinity chromatography. Analytical ultracentrifugation indicated that BetP forms trimers in detergent solution. Detergent-solubilized BetP can be reconstituted into proteoliposomes without loss of function, suggesting that BetP is a trimer in the bacterial membrane. Reconstitution with E.coli polar lipids produced 2D crystals with unit cell parameters of 182A x 154A, gamma=90 degrees exhibiting p22(1)2(1) symmetry. Electron cryo-microscopy yielded a projection map at 7.5A. The unit cell contains four non-crystallographic trimers of BetP. Within each monomer, ten to 12 density peaks characteristic of transmembrane alpha-helices surround low-density regions that define potential transport pathways. Small but significant differences between the three monomers indicate that the trimer does not have exact 3-fold symmetry. The observed differences may be due to crystal packing, or they may reflect different functional states of the transporter, related to osmosensing and osmoregulation. The projection map of BetP shows no clear resemblance to other secondary transporters of known structure.

Affinity Labels↗
PubMed2004

[Aneurysm of the subclavian artery. An unusual cause of dysphagia].

BACKGROUND: Dysphagia may be due to oral, pharyngeal or esophageal dysfunction and poses a frequent problem for the otolaryngologist. Motor disturbances, structural disorders, functional problems, congenital lesions and malignancies have to be excluded in an interdisciplinary diagnostic approach. Currently, vascular diseases play a minor role in the diagnosis of dysphagia. CASE REPORT: A 70-year-old female presented with constant dysphagia and a foreign body feeling in the throat of about 2 months duration. Palpation and ultrasound revealed a tumor situated in the right supraclavicular region. The lesion was identified as a true aneurysm of the subclavian artery by digital subtraction angiography. Successful resection and reconstruction was accomplished using a PTFE graft. DISCUSSION: Aneurysms of the subclavian artery are rare and in most cases related to thoracic outlet syndrome (TOS) or arteriosclerosis. It can be assumed that an increasingly aged population will present with an increasing incidence of diseases related to atherosclerosis. Moreover, the increasing incidence of specific infections may contribute to this phenomenon. This neglected disease should be included in the differential diagnosis when dealing with supraclavicular lesions, foreign body feeling or dysphagia.

Aged↗
PubMed2004

Endoscopic treatment of a mid-esophageal diverticulum.

Mid-esophageal diverticulum is a medical rarity. Only patients in whom the condition is symptomatic should receive treatment. Minimally invasive surgery via a thoracoscopic approach is currently the preferred treatment for the condition. This case report describes a 63-year-old woman with a symptomatic mid-esophageal diverticulum, which was successfully treated by endoscopic diverticulotomy using a needle-knife through a flexible endoscope.

Diverticulum, Esophageal↗
PubMed2004

Physicochemical characterization of protamine-phosphorothioate nanoparticles.

Protamine-oligonucleotide nanoparticles represent effective colloidal drug carriers for antisense phosphorothioate oligonucleotides (PTO). This study describes improvements in particle preparation and the physicochemical properties of the complexes prepared. The influence of component concentrations, length of the PTO chain and the PTO/protamine weight ratio on particle formation and size, shape and surface charge of the particles were studied in detail. Nanoparticles with diameters of 90-200nm were obtained, using protamine free base (PFB) and phosphorothioate in water. The chemical composition of the nanoparticles was analysed. More than 90% of the PTO could be assembled in the particle matrix using a > or = 1:2 ratio (w/w) of PTO and PFB. About 53-68% of the PFB was incorporated in the particle matrix. The complexes had a zetapotential of -19 up to +32 mV, depending on the PTO/PFB ratio. The kinetics of the assembly of this binary system were observed by dynamic light scattering (DLS) measurements and by sedimentation velocity analysis in the analytical ultracentrifuge (AUC). In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to verify the results of DLS and the ultracentrifuge measurements. According to sedimentation velocity analysis, the particles were only moderately stable in water and unstable in salt solutions. However, the colloidal solution in water could be stabilized by polyethylenglycol 20000 (PEG), which also led to an increase of stability in cell medium.

Chemical Phenomena↗
PubMed2003

Endoscopic treatment of benign gastrointestinal anastomotic strictures using argon plasma coagulation in combination with diathermy.

BACKGROUND: Initially, treatment for anastomotic strictures was surgical. Currently. however, endoscopic techniques are preferred. This study aimed to investigate the efficiency and safety of endoscopic treatment using argon plasma coagulation in combination with diathermy. METHODS: From 1995 to 2000, 49 patients with postsurgical anastomotic strictures of the esophagus or colon were referred for endoscopic treatment. In all cases, radiologic and endoscopic examination showed membranous or short strictures (diameter, 3-8 mm). Under direct endoscopic control, the scar tissue at the anastomotic line was incised radially with a polypectomy snare. The scar tissue between the incisions then was reduced carefully by argon plasma coagulation. RESULTS: All 49 patients were treated successfully with this combined endoscopic technique. Only for four patients was more than one endoscopic session (mean, 3.5; range, 2-6) needed to guarantee long-term success. No complications were encountered. CONCLUSIONS: Endoscopic argon plasma coagulation in combination with diathermy is a safe and effective technique for the treatment of short postsurgical gastrointestinal anastomotic strictures.

Adolescent↗
PubMed2003

Optimization of the preparation process for human serum albumin (HSA) nanoparticles.

Nanoparticles prepared by desolvation and subsequent crosslinking of human serum albumin (HSA) represent promising carriers for drug delivery. Particle size is a crucial parameter, in particular for the in vivo behaviour of nanoparticles after intravenous injection. The objective of the present study is the development of a desolvation procedure for the preparation of HSA-based nanoparticles under the aspect of a controllable particle size between 100 and 300 nm in combination with a narrow size distribution. A pump-controlled preparation method was established which enabled particle preparation under defined conditions. Several factors of the preparation process, such as the rate of addition of the desolvating agent, the pH value and the ionic composition of the HSA solution, the protein concentration, and the conditions of particle purification were evaluated. The pH value of the HSA solution prior to the desolvation procedure was identified as the major factor determining particle size. Varying this parameter, (mean) particle diameters could be adjusted between 150 and 280 nm, higher pH values leading to smaller nanoparticles. Washing the particles by differential centrifugation led to significantly narrower size distributions. The reproducibility of the particle size and particle size distribution under the proposed preparation conditions was demonstrated by sedimentation velocity analysis in the analytical ultracentrifuge and the cellular uptake of those nanoparticles was studied by confocal microscope imaging and FACS analysis. The stability of the resulting nanoparticles was evaluated by pH and buffer titration experiments. Only pH values distinctly outside the isoelectric pH range of HSA and low salt concentrations were able to prevent nanoparticle agglomeration.

Drug Delivery Systems↗
PubMed2003

[Selfexpandable metal stent for the treatment of a large anastomotic insufficiency after esophageal resection].

Mediastinal anastomotic leaks are still catastrophic events following surgical procedures and are still a therapeutic challenge. A variety of conservative and surgical procedures have been proposed for the management of this conditions. An aggressive surgical approach is associated with considerable morbidity and lethality. A conservative approach is indicated only in a few selected patients with minimal anastomotic leaks. With advances in minimally invasive techniques, interventional endoscopic procedures have become an established therapeutic approach in the treatment of anastomotic insufficiencies. Our case report demonstrates that transesophageal placement of a selfexpandable metal stent in combination with interventional drainage of the paraesophageal space is a safe and effective procedure in the management of a mediastinal anastomotic leaks.

Anastomosis, Surgical↗
PubMed2003

[Combined minimal-invasive procedures for resection of benign gastric wall tumors].

INTRODUCTION: With the increased use of endoscopic techniques, the rare, benign submucosal gastric tumors are being detected more frequently. We report our results with a combined laparoscopic-endoscopic approach for minimally invasive resection of these tumors. METHOD: The intraoperative endoscopy allows precise localization of the lesion by direct visualization and diaphanoscopy. Extragastral wedge resection of the stomach using the lifting method was carried out in patient with tumors of the anterior wall, lesser curvature and greater curvature. In tumors of the posterior wall, near the cardia or pylorus we performed an intragastric resection. One trocar with a balloon was inserted into the stomach. This trocar was used to introduce the endostapler into the stomach. RESULTS: We performed this combined laparoscopic-endoscopic resection in 9 patients (5 extragastral; 4 intragastral). The tumor size of intragastral resection was 34 +/- 5 mm (range 28 to 41 mm) and 36 +/- 7 mm (range 26 to 47 mm) in intragastral resections. The histological examination revealed 7 gastric stromal tumors and 2 leiomyomas. There were no intra- or postoperative complications. The oral nutrition started on p.o. day 2. Hospital stay ranged from 4 to 8 days (6.4 days). CONCLUSION: The minimally invasive combined laparoscopic-endoscopic resection of benign gastric wall tumors is a safe procedure with a low mortality and morbidity. The tumor localisation is the main criterion for decision on an extra- or intragastral approach.

Cardia↗
PubMed2003

A technique for endo-organ resection of gastric wall tumors using one intragastric trocar.

This report describes a new technique for combined laparoscopic and gastroscopic intragastric resection of benign gastric wall tumors. We performed this combined endo-organ procedure in five patients. Endo-organ intragastric resection is only used with posterior gastric wall tumors and tumors located near the cardia and the pylorus. For this approach, only one trocar is placed into the stomach for intragastric introduction of the endostapler. The video gastroscope allows intragastric vision. We recommend our procedure for the extirpation of small, benign, intramural gastric tumors, as a safe and very comfortable method for the patient.

Gastrectomy↗
PubMed2002

Repair of diaphragmatic rupture by laparoscopic implantation of a polytetrafluoroethylene patch.

Diaphragmatic hernias after blunt traumatic damage are serious complications, and diagnosis often might be delayed. In most cases, early symptoms are missed, but in the further posttraumatic period, patients experience recurrence of pulmonary dysfunction or intestinal symptoms such as obstruction, nausea, and pain. Most of these defects are diagnosed by laparotomy performed to investigate other major abdominal lesions. These diaphragmatic ruptures are managed by suturing using a thoracic or abdominal approach. An original diaphragmatic repair technique using a patch is presented. A 40-year-old woman was admitted to our clinic because of chronic abdominal pain. Chest x-ray and computed tomography scan showed a migration of the large intestine into the left hemithorax. A large diaphragmatic hernia was diagnosed and repaired laparoscopically using a patch. In the reported patient, laparoscopic suture of a diaphragmatic hernia using a polytetrafluoroethylene (PTFE) (GORETEX) patch proved to be safe, successful, elegant, and uneventful.

Adult↗