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Michael Rieger

Publications and source records attributed to Michael Rieger.

At least 19 recordsLinked to original sources
PubMed2007

Rituximab-augmented myeloablation for first-line autologous stem cell transplantation for mantle cell lymphoma: effects on molecular response and clinical outcome.

BACKGROUND AND OBJECTIVES: Autologous stem cell transplantation (ASCT) is effective in mantle cell lymphoma (MCL). We investigated whether incorporation of rituximab into the high-dose regimen might further improve the results of ASCT in patients with MCL. DESIGN AND METHODS: In a prospective phase II study, patients with newly diagnosed MCL were treated with a sequential dose-escalating therapy comprising standard chemotherapy for remission induction, intensive ara-C-containing chemotherapy for mobilization of stem cells, and myeloablative therapy followed by ASCT. The myeloablative regimen consisted of total body irradiation and high-dose cyclophosphamide supplemented with two doses (375 mg/m3) of rituximab. Outcome parameters (toxicity, clinical and molecular response as assessed by allele-specific IGH real-time quantitative polymerase chain reaction (RQ-PCR), event-free survival, and overall survival) were compared with those of 34 historical controls treated identically but without rituximab. RESULTS: Thirty-four patients were accrued. Whereas engraftment, toxicity and clinical response were not different from those in controls, event-free survival was significantly increased with rituximab (not reached vs. 43 months; hazard ratio 0.38; p=0.036). This was associated with a trend for a superior molecular response rate in 11 study vs. 10 control patients with a marker available (73% vs. 30%, p=0.086) despite similar levels of lymphoma contamination of the stem cell inocula infused. INTERPRETATION AND CONCLUSIONS: Incorporation of two standard doses of rituximab into the myeloablative regimen might improve outcome of up front ASCT for MCL, allowing long-term disease control to an extent previously not reached in this disease.

Adult↗
PubMed2006

Use of an inspiratory impedance threshold valve during chest compressions without assisted ventilation may result in hypoxaemia.

INTRODUCTION: Although the concept of intermittent airway occlusion with the inspiratory impedance threshold valve (ITV) is a well-recognised strategy for improving efficiency of cardiopulmonary resuscitation (CPR), little is known about possible pulmonary side effects. METHODS: After a baseline chest CT-scan, 24 pigs with beating hearts undergoing apnoeic oxygenation received an injection of a contrast medium and were then assigned randomly to either active compression-decompression CPR with ITV (ACD ITV CPR), ACD CPR alone, or standard-CPR with ITV (standard-ITV CPR), or standard-CPR alone. After a maximum of 5 min of chest compressions or if oxygen saturation dropped below 70%, the experiment was stopped, haemodynamic variables and blood gas values were measured, and another CT-scan was performed; all animals underwent a 30 min recovery-period and a third subsequent CT-scan. RESULTS: At baseline arterial oxygen saturation by pulse oxymetry was 99% in all four groups; in both the ACD ITV CPR and the standard-ITV CPR groups, arterial oxygen saturation dropped below 70% within 126+/-9s, whereas chest compressions in all ACD CPR and standard-CPR pigs were performed over 5 min (P<0.001). Before stopping chest compressions arterial oxygen pressure decreased in the ACD ITV CPR group from 426+/-96 to 42+/-8 mmHg while it decreased in the ACD CPR group only from 415+/-116 to 197+/-127 mmHg (P<0.001 between groups); in the standard-ITV CPR group arterial oxygen partial pressure decreased from 427+/-109 to 34+/-5 mmHg while oxygen partial pressure decreased only from 467+/-44 to 144+/-98 mmHg in the standard-CPR group (P<0.004 between groups). After the second CT scan arterial oxygen partial pressure decreased further to 19+/-2 mmHg in the ACD ITV CPR versus 210+/-41 mmHg in the ACD CPR group; to 20+/-2 mmHg in the standard-ITV CPR versus 148+/-33 mmHg in the standard-CPR group. Lung-density values (Hounsfield units) were significantly higher in the ACD ITV CPR versus ACD CPR group (-134+/-54 versus -330+/-77) and standard-ITV CPR versus standard-CPR group (-98+/-50 versus -387+/-42). After a 30 min recovery-period, there were no significant differences in arterial oxygen partial pressure (ACD ITV CPR 275+/-110 mmHg versus ACD CPR 379+/-111 mmHg and standard-ITV CPR 265+/-138 mmHg versus standard CPR 367+/-55 mmHg). Furthermore, there were no differences in lung density values between groups after 30 min of recovery. CONCLUSION: In this animal model with a beating heart, intermittent airway obstruction through an ITV combined with apnoeic oxygenation and without active ventilation resulted in hypoxaemia due to transiently impaired lung function.

Airway Resistance↗
PubMed2006

Is the bare spot a consistent landmark for shoulder arthroscopy? A study of 20 embalmed glenoids with 3-dimensional computed tomographic reconstruction.

PURPOSE: Our aim was to test a published methodology for arthroscopically quantifying glenoid bone loss for its dependability in a cadaver-based anatomic study with 3-dimensional (3-D) computed tomographic (CT) reconstructions of 20 embalmed glenoids. METHODS: Manual macroscopic measurements were made in a standardized fashion. In addition, we marked the center of the visible bare spot in 20 embalmed glenoids with a titanium pin. The shoulder joints were carefully selected for intact rotator cuff, missing capsule-labral deficiency, and absence of severe cartilage degeneration. 3-D reconstructed CT scans were evaluated for consistency of the bare spot. RESULTS: The mean distance from the bare spot to the anterior margin measured manually was 10.9 mm (CT-based, 13.9 mm), to the posterior margin 13.7 mm (CT-based, 16.4 mm), and to the inferior margin 9.7 mm (CT-based, 15.1 mm). Distances were significantly different. CONCLUSIONS: The bare spot did not prove its consistency in 20 carefully selected specimens. Therefore, we conclude that this methodology is not a reliable way to intraoperatively determine bony glenoid deficiency. CLINICAL RELEVANCE: We recommend preoperative bilateral CT scans for evaluation of bony glenoid deficiency for exact quantification of the bone loss.

Aged↗
PubMed2006

Prospective evaluation of patellar tendon graft fixation in anterior cruciate ligament reconstruction comparing composite bioabsorbable and allograft interference screws.

PURPOSE: Bioabsorbable interference screws have proved to be biologically safe and to provide adequate graft fixation. Metallic interference screws have therefore been continuously replaced over the years. However, degradation times are highly variable, and bony replacement of the screw does not always occur in human beings. Composite interference screws have recently been introduced to enhance bony integration. We evaluated 2 different composite interference screws and compared them with an allograft interference screw over a 2-year period after anterior cruciate ligament (ACL) reconstruction with an autologous bone-patellar tendon-bone graft. METHODS: Three groups of patients were prospectively evaluated. Poly-L-lactid acid/hydroxyapatite composite screws (BioRCI-HA; Smith & Nephew, Andover, MA) (group A), poly-L-lactid acid/beta-tricalcium phosphate composite screws (Bilok; Atlantech, Radevormwald, Germany) (group B), or allograft interference screws (CorlS; Regeneration Technologies, Alachua, FL) (group C) were used for tibial fixation of a patellar tendon autograft in ACL reconstruction. Each group consisted of 20 patients (mean age, 32.2 +/- 10.9 years in group A, 32.3 +/- 10.6 years in group B, and 31.1 +/- 6.6 years in group C) with no significant (P < .05) differences in age, sex, and time of follow-up. Subjective and clinical International Knee Documentation Committee parameters were evaluated preoperatively and at 3, 12, and 24 months postoperatively; computed tomography scans were obtained postoperatively and at 3, 12, and 24 months; and magnetic resonance imaging (MRI) scans were obtained at 3 and 24 months postoperatively. RESULTS: Screw breakage during insertion occurred in 2 cases (1 in group A and 1 in group B). There was no significant (P < .05) difference in subjective and clinical results at any time of follow-up. No inflammatory response could be detected on MRI in any of the patients in all groups. Computed tomography scans documented complete bone block incorporation at 3 months in all groups. Both composite interference screws showed signs of degradation but were still clearly visible 24 months after ACL reconstruction. At 12 months, a sclerotic rim around the screw cavity could be outlined in group B only. No bony replacement had taken place up to 24 months postoperatively in group A or B. In group C the allograft bone screw was completely integrated and barely visible after 24 months. CONCLUSIONS: All 3 screw types provided adequate graft fixation and were associated with excellent clinical results and no inflammatory response on MRI. Ultimately, a resorbable screw has to be replaced by bone to facilitate revision surgery. Formation of a sclerotic rim around the outline of the screw makes later bony replacement (group B) unlikely. After 24 months, complete bony integration had only taken place when allograft screws were used. CLINICAL RELEVANCE: At 24 months, no advantage of composite screw materials over conventional bioabsorbable screws could be detected. If composite materials will be of any advantage with respect to bony replacement has to be observed with longer-term follow-up. The allograft bone screw was completely incorporated and replaced by cancellous bone after 24 months. Unfortunately, the screw's more complicated handling, higher cost, and limited availability impair the possibilities for its standard clinical use.

Absorbable Implants↗
PubMed2006

Frameless stereotactic cannulation of the foramen ovale for ablative treatment of trigeminal neuralgia.

OBJECTIVE: Ablative neurosurgical treatment of trigeminal neuralgia, including percutaneous radiofrequency thermocoagulation, requires cannulation of the foramen ovale. To maximize patient security and cannulation success, a frameless stereotactic system was evaluated in a phantom study, a cadaveric study, and a preliminary clinical trial. METHODS: Frameless stereotaxy using an optical navigation system, an aiming device, and a noninvasive vacuum mouthpiece-based registration and patient fixation technique was used for the targeting of a test body based on 1-, 3-, and 5-mm axial computed tomographic slices and of the foramen ovale in three cadavers and 15 patients based on 3-mm axial computed tomographic slices. RESULTS: The mean normal (x/y) localization accuracy/standard deviation (n = 360) was 1.31/0.67 mm (1-mm slices), 1.38/0.65 mm (3-mm slices), and 1.84/0.96 mm (5-mm slices). Significantly better results were achieved with 1- and 3-mm slices when compared with 5-mm slices (P < 0.001). The foramen ovale (3 x 6 mm) was successfully cannulated at the first attempt in all cadavers and patients, which indicates clinical localization accuracies better than 1.5 mm in the anteroposterior and 3 mm in the medial-lateral directions. CONCLUSION: Based on the noninvasive Vogele-Bale-Hohner vacuum mouthpiece, there is no need for invasive head clamp fixation. Imaging, real laboratory simulation, and the actual surgical intervention can be separated in time and location. The presented data suggest that frameless stereotaxy is a predictable and reproducible procedure, which may enhance patient security and cannulation success independent of the surgeon's experience.

Aged↗
PubMed2006

Traumatic arterial injuries of the extremities: initial evaluation with MDCT angiography.

OBJECTIVE: The purpose of this study was to retrospectively assess the accuracy of MDCT angiography as the initial diagnostic technique to depict arterial injury in patients with extremity trauma. MATERIALS AND METHODS: Over 36 months, 87 patients (16 females and 71 males; age range, 16-87 years) with clinically suspected arterial injury after extremity trauma underwent 4-MDCT angiography and 67 ultimately underwent surgery. Eighty patients had blunt injuries, and seven had penetrating injuries. The presence of arterial involvement was investigated prospectively by the radiologist in charge and retrospectively by two independent radiologists. Each detected arterial lesion was then characterized as a spasm, stenosis, occlusion, or rupture. The standard of reference was surgery in 67 patients, angiography in two patients, and clinical and radiologic follow-up findings in 18 patients. MDCT angiography was assessed by means of receiver operating characteristic (ROC) curve analysis for lesion detection and Spearman's rank correlation test for lesion characterization. Image quality, lesion depiction, and artifacts were subjectively assessed. RESULTS: Sixty-two traumatic arterial lesions were confirmed at surgery in 55 patients. MDCT angiography yielded high accuracy in detection (area under the ROC curve [Az] = 0.96; p < 0.001) and characterization (r = 0.94; p < 0.001) of traumatic arterial injuries and in recognizing an underlying dissection (Az= 0.82; p < 0.001). Prospective sensitivity and specificity were 95% and 87%, respectively, and retrospective sensitivity and specificity were 99% and 87%, respectively. MDCT angiography was considered to be sufficient for a reliable diagnosis in 83 patients (p < 0.001). Image quality and lesion depiction on MDCT angiograms were considered to be good and artifacts were considered mild with substantial interobserver agreement (kappa, 0.62-0.69). CONCLUSION: MDCT angiography provides significant and reproducible technique for the detection and characterization of arterial injuries to the extremities with high image quality and vascular delineation.

Adolescent↗
PubMed2005

The genome of the kinetoplastid parasite, Leishmania major.

Leishmania species cause a spectrum of human diseases in tropical and subtropical regions of the world. We have sequenced the 36 chromosomes of the 32.8-megabase haploid genome of Leishmania major (Friedlin strain) and predict 911 RNA genes, 39 pseudogenes, and 8272 protein-coding genes, of which 36% can be ascribed a putative function. These include genes involved in host-pathogen interactions, such as proteolytic enzymes, and extensive machinery for synthesis of complex surface glycoconjugates. The organization of protein-coding genes into long, strand-specific, polycistronic clusters and lack of general transcription factors in the L. major, Trypanosoma brucei, and Trypanosoma cruzi (Tritryp) genomes suggest that the mechanisms regulating RNA polymerase II-directed transcription are distinct from those operating in other eukaryotes, although the trypanosomatids appear capable of chromatin remodeling. Abundant RNA-binding proteins are encoded in the Tritryp genomes, consistent with active posttranscriptional regulation of gene expression.

Animals↗
PubMed2005

The potential of venous air embolism ascending retrograde to the brain.

A bench study was performed to investigate the potential of air bubbles entering a central vein via a central venous catheter to ascend retrograde to the brain. The results support the hypothesis that air bubbles may rise retrograde against the venous blood flow, depending on bubble size, central vein diameter and cardiac output. A review of radiological findings in published case reports indicates that the occurrence of retrograde cerebral air embolism is underestimated.

Animals↗
PubMed2004

Abdominal aortic aneurysms: virtual imaging and analysis through a remote web server.

The study describes the application of a web-based software in the planning of the endovascular treatment of abdominal aortic aneurysms (AAA). The software has been developed in the framework of a 2-year research project called Aneurysm QUAntification Through an Internet Collaborative System (AQUATICS); it allows to manage remotely Virtual Reality Modeling Language (VRML) models of the abdominal aorta, derived from multirow computed tomography angiography (CTA) data sets, and to obtain measurements of diameters, angles and centerline lengths. To test the reliability of measurements, two radiologists performed a detailed analysis of multiple 3D models generated from a synthetic phantom, mimicking an AAA. The system was tested on 30 patients with AAA; CTA data sets were mailed and the time required for segmentation and measurement were collected for each case. The Bland-Altman plot analysis showed that the mean intra- and inter-observer differences in measures on phantoms were clinically acceptable. The mean time required for segmentation was 1 h (range 45-120 min). The mean time required for measurements on the web was 7 min (range 4-11 min). The AQUATICS web server may provide a rapid, standardized and accurate tool for the evaluation of AAA prior to the endovascular treatment.

Angiography↗
PubMed2004

CT virtual reality in the preoperative workup of malunited distal radius fractures: preliminary results.

Our objective was to evaluate the usefulness of CT virtual preoperative planning in the surgical repositioning of malunited distal radius fracture. Eleven patients with malunited distal radius fracture underwent multislice CT of both wrists. A preoperative workup was performed in a virtual reality environment created from the CT data sets. Virtual planning comprised three main procedures, carrying out the virtual osteotomy of the radius, prediction of the final position of the distal radius after osteotomy and computer-assisted manufacturing of a repositioning device, which was later placed at the surgical osteotomy site to reposition objectively the distal radius fragment before fixation with the osteosynthesis. All patients tolerated the surgical procedure well. During surgery, the orthopedic surgeons were not required in any of the cases to alter the position of the distal radius that was determined by the repositioning device. At postoperative follow-up, the anatomic relationship of the distal radius was restored (radial inclination, 21.4 degrees ; volar tilt, 10.3 degrees ; ulnar variance, 0.5 mm). Clinically, a significant improvement of pronation (P=0.012), supination (P=0.01), flexion (P=0.001) and extension (P=0.006) was achieved. Pain decreased from 54 to 7 points. CT virtual reality is a valuable adjunct for the preoperative workup and surgical reposition of malunited distal radius fractures.

Adult↗
PubMed2004

Role of free-tissue transfer in the treatment of recalcitrant palatal fistulae among patients with cleft palates.

Recurrent palatal fistulae present a particularly vexing problem for patients with cleft lips and palates and their surgeons. When primary closure fails, conventional wisdom and the standard of care suggest local flap techniques for defect closure. For the large majority of patients, this approach is successful. There is, however, a small subset of patients who undergo multiple surgical procedures in unsuccessful attempts to close recalcitrant fistulae, particularly at the anterior, densely scarred, hard palate. In this setting, repair calls for the introduction of well-vascularized pliable tissue to close the defect and to avoid hampering further palatal growth. Local muscle flaps and oral axial pattern flaps have been advocated and used successfully. However, those approaches have their own drawbacks, such as multiple surgical interventions, patient compliance, and intraoral scarring. In an effort to avoid the problems associated with local flaps, distant microvascular tissue transfers were investigated. During a 6-year period, six free-tissue transfers were performed as a primary means of treating recalcitrant palatal fistulae. Three dorsalis pedis flaps and three osseous angular scapular flaps were used. The conditions of all patients improved, with five patients achieving complete long-term closure of the palatal defect. This experience indicates that modern microvascular techniques have reached a level of success commensurate with that of other flap techniques; therefore, it is concluded that free-tissue transfer should be considered as a primary means of addressing these difficult cleft problems.

Adolescent↗
PubMed2004

Successful therapy of severe pneumonia-associated ARDS after pneumonectomy with ECMO and steroids.

Pneumonia and acute respiratory distress syndrome are life-threatening complications after pneumonectomy carrying high mortality. Because pulmonary reserve is inadequately low, an effective therapeutic strategy is needed to treat hypoxia. Extracorporeal membrane oxygenation is a highly effective method to reverse hypoxia in patients with acute respiratory distress syndrome, but has only once been described in a patient with postpneumonectomy pulmonary edema. We report a case of successful extracorporeal membrane oxygenation therapy in a patient with pneumonia-associated acute respiratory distress syndrome after pneumonectomy. Methylprednisolone therapy caused a dramatic improvement of pulmonary and systemic organ function.

Anti-Inflammatory Agents↗
PubMed2004

CT-MIBI image fusion: a new preoperative localization technique for primary, recurrent, and persistent hyperparathyroidism.

BACKGROUND: Successful minimally invasive or imaging-guided operations in patients with primary, recurrent, and persistent hyperparathyroidism are based on the reliability of preoperative parathyroid localization studies. The CT-MIBI image fusion promises a higher diagnostic accuracy than current imaging procedures. The aim of our study was to assess its reliability in correctly detecting enlarged parathyroid glands. METHODS: In a prospective study 24 consecutive patients underwent CT-MIBI image fusion as preoperative parathyroid localization procedure. The results of technetium 99m sestamibi single photon emission computed tomography (MIBI-SPECT) alone, today the standard method in parathyroid imaging, and CT-MIBI image fusion were analyzed by a blinded reviewer, and the imaging results were compared with the intraoperative findings. RESULTS: For CT-MIBI image fusion a sensitivity of 93% and a specificity of 100% in correctly detecting the position of enlarged parathyroid glands was calculated and compared with a sensitivity of MIBI-SPECT of 31% and a specificity of 87% (P<.001). This new imaging technique enabled us to successfully treat 22 of our patients (92%) with imaging-guided surgery. Twenty (83%) underwent unilateral or minimally invasive operations. CONCLUSIONS: CT-MIBI image fusion appears to be superior to MIBI-SPECT in preoperative parathyroid imaging. CT-MIBI image fusion can be performed on existing CT- and MIBI-SPECT units. We recommend this method for preoperative localization in patients with primary, recurrent and persistent hyperparathyroidism.

Adult↗