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Biomedical subjects

M Rieger

Publications and source records attributed to M Rieger.

At least 37 records · Page 2Linked to original sources
PubMed2002

[Modern CT diagnosis of acute thoracic and abdominal trauma].

PURPOSE: To evaluate a modified algorithm in the diagnostic management of polytraumatized patients by using whole body multislice CT (MSCT) as primary diagnostic tool. MATERIAL AND METHODS: Between June 1999 and October 2000 532 polytraumatized patients were referred to the emergency department. 336 polytraumatized patients were primarily evaluated using whole body MSCT according to the "Innsbruck Emergency Algorithm." MSCT is performed immediately after cardiovascular stabilization of the patient. During the initial stabilization period free intraabdominal fluid is excluded or demonstrated by abdominal ultrasound. Time-consuming conventional radiographs are omitted with exception of an optimal chest X-ray. In patients with suspected or obvious arterial injuries or fractures the multislice-CT-dataset is used to perform 2D and 3D reconstructions in order to optimize visualization of additional skeletal and vascular injuries. RESULTS: By means of whole body MSCT it was possible to detect all injuries. The diagnostic advantage of whole body MSCT as compared to conventional X-ray was analyzed in 111 consecutive polytraumatized patients with an injury severity score (ISS) of 34.77. The early use of MSCT shortened the time for diagnostic work-up substantially (approximately 50%). CONCLUSION: Whole body multislice-CT used as primary diagnostic tool in the management of polytraumatized patients allows for a fast, accurate and comprehensive diagnostic work-up.

Abdominal Injuries↗
PubMed2002

Cardiac failure and multiple organ dysfunction syndrome in a patient with endocrine adenomatosis.

In this case report, we present the successful therapy of severe cardiac failure in pituitary adrenal insufficiency. A previously healthy 56-year-old-man in pituitary coma due to an atypical variant of multiple endocrine adenomatosis (pituitary adenoma and pheochromocytoma) suffered from cardiac failure resistant to catecholamine and standard hydrocortisone therapy. After two bolus injections of dexamethasone (2 x 24 mg) mean arterial pressure and cardiac function dramatically improved, probably due to restoration of permissive effects on catecholamine action and reversal of pathophysiological mechanisms of cardiac failure. We conclude that in patients with severe cardiovascular failure in pituitary coma the administration of potent glucocorticoids may be more effective in reversing cardiovascular failure than standard dosages of hydrocortisone.

Adenoma↗
PubMed2002

Stage 3 Kienböck's disease: reconstruction of the fractured lunate using a free vascularized iliac bone graft and external fixation.

Eighteen patients with stage 3 Kienböck's disease were treated by débridement of the necrotic core of the lunate and implantation of a free vascularized corticocancellous iliac bone. The wrist was stabilized with an external fixator during healing. The efficiency of the procedure for restoring the structure of the fractured lunate, preventing carpal collapse and improving the clinical outcome was assessed at a mean follow-up of 5 years. The graft became incorporated in the lunate in 16 of the 18 patients and no fracture of the reconstructed lunate or carpal collapse occurred in these cases. The graft did not integrate and was resorbed in the other two patients.

Adolescent↗
PubMed2002

[Distal radius fractures and concomitant lesions. Experimental studies concerning the pathomechanism].

Since Colles (1814) first described a distal radius fracture and the publication by Dupuytren (1834), the frequency of and problems surrounding these fractures were increasingly recognised. Not only the treatment but also the formation and type of fracture were repeatedly analysed. The various theories concerning the pathomechanism led to names such as: "tear fracture", "bend fracture", "thrust fracture", "compression fracture", "snap fracture" and others. In our experimental studies we attempted to simulate the pathomechanism of distal radius fractures and present them pictorially. With the help of a materials testing machine, 63 prepared cadaver arms were hyperextended in the wrist joint until a radius fracture occurred. The concomitant lesions were registered radiologically and by dissection. Moreover, additional cadaver arms were deep-frozen and examined by means of computer tomography and cryosection according to Kathrein. Through experimental hyperextension it was possible to generate dorsal, central, and palmar types of fractures. We produced 42 dorsal, 14 central and 7 palmar fractures. Fundamentally, it seems that the fracture depends on the extent in which the carpal bones of the proximal row are pressed against the dorsal, central or palmar part of the articular surface of the distal radius. The subsequent dissection showed in 40 cases (63 %) mostly multiple concomitant lesions and in 23 cases (37 %) none of these. The reason for concomitant lesions may be the proportion of bone stability to the strength of ligaments. Most frequently (27 cases, i.e. 43 %), we found a destabilisation of the articular disk with or without a bony avulsion fragment (fracture of the ulnar styloid). We also commonly found ruptures of the interosseous ligaments between scaphoid and lunate (20 cases, i.e. 32 %) and lunate and triquetrum (11 cases, i.e. 18 %). It is difficult to apply knowledge gained from experimental studies on preserved cadaver arms clinically. There are of course no physiological reflexes and the slow fracture process must be taken into consideration. This holds true not only for concomitant lesions but also for the type of fracture. On the other hand, in these experimental studies it was possible to generate many realistic types of fractures with their concomitant lesions.

Biomechanical Phenomena↗
PubMed2002

Extraanatomical coronary artery bypass grafts on the beating heart for management of the severely atherosclerotic ascending aorta.

BACKGROUND: Crossclamping a severely atherosclerotic ascending aorta carries a significant risk of stroke in coronary artery bypass grafting. Besides other techniques aortic no touch concepts are increasingly applied for management of this problem. METHODS: Out of 407 patients undergoing epiaortic scanning during coronary artery bypass grafting 38 (9.3%) exhibited severe ascending aortic atherosclerosis. 22 of these patients (18 male, 4 female, age 72 (57-79) years, Parsonnet Score 11 (0-18), Euro Score 8 (2-13), McSPI Stroke Risk Index 6 (1-30) %) were operated on using a beating heart and aortic no touch technique. All patients received at least one internal mammary artery (IMA) in situ graft and additional extraanatomical bypass conduits: venous Y-graft from the IMA (n=14), arterial Y-graft from the IMA (n=3), vein graft from the axillary artery (n=3), vein graft from the IMA stump (n=2), vein graft from the innominate artery (n=2). RESULTS: No stroke occurred. The rate of perioperative myocardial infarction (CKMB rt; 50 U/l) was 5/22. Median ICU length of stay was 54 (15-1245) h. Hospital mortality was 2/22. Pre- and postoperative angina class (CCSC) were 3.3 +/- 0.9 and 1.4 +/- 0.9 respectively (p<0.001). After a median follow up period of 8 months 3 deaths, one stroke, and one myocardial infarction occurred. On 3D multislice CT scan reconstructions which were performed in 13 patients during the first postoperative year all IMA grafts to the LAD and 11 out of 13 extraanatomical vein grafts were shown to be patent. CONCLUSION: Performance of beating heart extraanatomical coronary artery bypass grafts for management of a heavily diseased ascending aorta can result in a very low stroke rate despite a considerable stroke risk. The complexity of the procedures may be reflected by a relatively high rate of perioperative myocardial infarctions. Perioperative mortality as well as short term patency of extraanatomical bypass grafts seem to be acceptable.

Aged↗
PubMed2001

[Computer-assisted retrograde drilling of osteochondral lesions of the talus].

Treatment principles of osteochondral lesions of the talus usually consist of debridement of the chondral part and methods that attempt to stimulate revascularization of the necrotic bony part of the lesion. The latter is mostly achieved through multiple drilling of the subchondral zone. Dorsomedial talar dome lesions are frequently inaccessible with antegrade drilling techniques. In addition, if the cartilage surface over the bony lesion is still intact, it can be injured by antegrade drilling. To overcome these potential problems, retrograde drilling techniques have been developed using drill guides or intraoperative fluoroscopy. Our proposed method of computer-assisted retrograde drilling is an advancement of these techniques. The use of 3D navigation provides the possibility for placing a guide wire exactly in the center of the lesion defined on preoperative MRI or CT scans. This guide wire can then be overreamed with cannulated reamers followed by retrograde bone grafting of the lesion or allows multiple retrograde drilling of the subchondral plate using a parallel drill guide. We found that computer-assisted retrograde drilling could improve precision, avoid misplacement of guide wires, and reduce the time of surgery and intraoperative fluoroscopy.

Arthroscopy↗
PubMed2001

Tibial tunnel enlargement following anterior cruciate ligament reconstruction with patellar tendon autograft.

PURPOSE: The purpose of this study was to prospectively evaluate changes in the tibial bone tunnel following endoscopic anterior cruciate ligament (ACL) reconstruction with patellar tendon autograft. We used computed tomography (CT) sequentially to monitor the time course of these changes over a 2-year period and correlated the results to clinical outcome and instrumented laxity measurements. TYPE OF STUDY: Case series. METHODS: Thirty-four patients (11 women, 23 men; mean age, 26.4 +/- 4.5 years) who underwent endoscopic patellar tendon ACL reconstruction, were evaluated clinically according to IKDC, Lysholm, and Tegner scores as well as with respect to changes in tibial tunnel morphology over a 2-year period. Subsequent CT scans were performed at 1 and 6 weeks and at 3, 6, 12, and 24 months postoperatively. The tibial bone tunnel was measured in the sagittal and coronal planes at 5 different levels (L1 to L5). RESULTS: The diameters of the tibial tunnel increased an average overall by 30.6% in the sagittal plane and 16.4% in the coronal plane within 2 years. The enlargement was significantly higher (P <.05) in the mid portion of the tunnel (L 2/3: 44.0% and 47.9% in the sagittal and 29.8% and 29.9% in the coronal plane, respectively), which resulted in a uniform cavity-type appearance. The percentage of change in tunnel size was significantly higher (P <.05) within the first 6 weeks following surgery compared with all other time intervals. No correlation between the amount of tunnel enlargement and the clinical results or between tunnel enlargement and KT-1000 measurements could be detected. CONCLUSIONS: Endoscopic ACL reconstruction is associated with tibial tunnel enlargement, which is already present within weeks following surgery. However, no negative effects on the clinical results were found over a 24-month period in our study population.

Adult↗
PubMed2001

[Radiation exposure in single slice and multi-slice spiral CT (a phantom study)].

PURPOSE: The purpose of study was to compare patient dose applying singleslice- and multislice-spiral CT. METHODS: The examinations were performed with a singleslice-spiral CT (Highspeed Advantage; GE Medical Systems; Milwaukee, USA) and with a multislice CT systems (LightSpeed QX/i GE Medical Systems; Milwaukee, USA). For the determination of the radiation exposure (absorbed dose) a selection of most executed protocols (thorax-helical, abdomen-helical, petrous bone-axial, head-axial) were simulated using an Alderson Rando Phantom. The dose was determined by means of lithiumfluorid-thermoluminiscence dosimeters (TLD-GR 200). RESULTS: For thorax and abdomen protocols higher energy dose values could be found using a multislice CT. On the average the energy dose values were increased by 2.6 on an average in relation to single slice spiral CT. The energy dose values of the multisclice CT using head protocols could be reduced by 30% in relation to single slice spiral CT due to suitable parameter selections. The energy dose applying a petrous bone protocol resulted in an average increase by a factor 1.5 using a multislice CT. CONCLUSION: Using the new multislice CT technique protocol strategies must be optimized regarding the patient doses. Users can operate critically in the sense of the radiation protection only if they are aware of the occurring dose amounts to the patient.

Equipment Design↗
PubMed2001

Serial CT volume measurements after endovascular aortic aneurysm repair.

PURPOSE: To evaluate the efficacy of transluminal stent-graft placement in aortic aneurysms using postoperative enhanced spiral computed tomographic (CT) volumetric measurements of the aneurysm sac, the intra-aneurysmal vascular channel (IAVC), the thrombus, and the stent-graft. METHODS: Among 53 patients (45 men; mean age 74 years, range 59-85) who underwent elective endovascular aortic aneurysm repair, 37 patients with 27 abdominal and 10 thoracic aortic aneurysms completed at least a 6-month follow-up that included computerized CT volumetric analysis prior to discharge and at 3, 6, 12, 24, and 36 months. A variety of bifurcated (n = 23) and tube (n = 14) stent-grafts were observed for signs of endoleak and aneurysm enlargement. RESULTS: Mean follow-up was 16 months (range 6-48). Total aneurysm volumes and thrombus volumes decreased, whereas IAVC and stent-graft volumes increased over time. Between the postoperative and 12-month imaging studies, reductions in total aneurysm (p 0.011) and thrombus (p < 0.001) volumes were significant. No statistically significant difference in volume changes for the aneurysm sac (p = 0.555) or the thrombus (p = 0.920) was found when comparing the 24 patients without primary leak to the 12 with primary type-II leak. In all 5 cases with secondary leak, the volume of the aneurysm sac increased after initial shrinkage. CONCLUSIONS: Postoperative CT volumetric analysis is an effective tool for evaluating the outcome of endovascular aortic aneurysm repair. Thrombus volume measurements are more accurate than total aneurysm volumes. In patients in whom contrast agents are contraindicated, volume measurements can also be obtained without the use of contrast.

Age Factors↗
PubMed2000

Sequence and analysis of chromosome 3 of the plant Arabidopsis thaliana.

Arabidopsis thaliana is an important model system for plant biologists. In 1996 an international collaboration (the Arabidopsis Genome Initiative) was formed to sequence the whole genome of Arabidopsis and in 1999 the sequence of the first two chromosomes was reported. The sequence of the last three chromosomes and an analysis of the whole genome are reported in this issue. Here we present the sequence of chromosome 3, organized into four sequence segments (contigs). The two largest (13.5 and 9.2 Mb) correspond to the top (long) and the bottom (short) arms of chromosome 3, and the two small contigs are located in the genetically defined centromere. This chromosome encodes 5,220 of the roughly 25,500 predicted protein-coding genes in the genome. About 20% of the predicted proteins have significant homology to proteins in eukaryotic genomes for which the complete sequence is available, pointing to important conserved cellular functions among eukaryotes.

Arabidopsis↗
PubMed2000

Progress in Arabidopsis genome sequencing and functional genomics.

Arabidopsis thaliana has a relatively small genome of approximately 130 Mb containing about 10% repetitive DNA. Genome sequencing studies reveal a gene-rich genome, predicted to contain approximately 25000 genes spaced on average every 4.5 kb. Between 10 to 20% of the predicted genes occur as clusters of related genes, indicating that local sequence duplication and subsequent divergence generates a significant proportion of gene families. In addition to gene families, repetitive sequences comprise individual and small clusters of two to three retroelements and other classes of smaller repeats. The clustering of highly repetitive elements is a striking feature of the A. thaliana genome emerging from sequence and other analyses.

Agriculture↗
PubMed2000

[Perfusion-index values evaluated by dynamic magnetic resonance imaging in advanced rectal carcinoma. A new predictor of response to preoperative radiochemotherapy?].

PURPOSE: The aim of our study was to evaluate in vivo the influence of tumor microcirculation data on therapy outcome. PATIENTS AND METHODS: Tumor perfusion data of primary rectal carcinoma (n = 14, cT3) who underwent preoperative chemoradiation have been analyzed (Table 1). The perfusion data were acquired at the beginning and at the end of therapy by use of an ultrafast T1-mapping sequence on a whole-body magnetic resonance imager. The gadolinium-DTPA concentration-time-curves were evaluated for arterial blood and tumor before, during and after intravenous constant rate infusion and from that the perfusion index (PI) was calculated. Subsequent resection of the tumors allowed for a correlation of perfusion index values with the pathological classification. RESULTS: Nine patients showed a T downstaging (ypT0-2, group 1), 5 patients did not (ypT3, group 2). The initial mean perfusion index value of group 1 (n = 9) was 8.2 ml/min/100 g (+/- 2) and for group 2 (n = 5) 10.4 ml/min/100 g (+/- 0.4). The difference in perfusion index values before chemoradiation between group 1 and group 2 was significant different (p = 0.012, Mann-Whitney test). The perfusion index value at the end of therapy of group 1 (n = 6) was 9.6 ml/min/100 g (+/- 2.8) and for group 2 (n = 4) 10.7 ml/min/100 g (+/- 1.6). The difference in perfusion index values after chemoradiation between group 1 and group 2 was not significant different (Table 2). CONCLUSION: Our used perfusion index value combines 2 parameters: tumor perfusion and extraction fraction. Therefore a significant negative influence on therapy outcome of high perfusion index values could be explained possibly by areas with a high portion of high perfusion (e.g. av-shunts) and a low extraction fraction (= low exchange of nutrients). However, we could show a significant negative influence of high perfusion index values on therapy outcome (p = 0.012). Because the tumor stage has a significant influence on tumor-free survival, there is a possibility for using initial perfusion index values as a new prognostic factor in rectal carcinoma without sphincter infiltration undergoing a preoperative chemoradiation. To examine this hypotheses a prospective trial is in preparation.

Adult↗
PubMed2000

Acute respiratory failure associated with catastrophic antiphospholipid syndrome.

We present a case of multiple organ dysfunction syndrome with acute respiratory failure due to alveolar haemorrhage associated with antiphospholipid antibodies in a 42-year-old woman with a medical history of antinuclear antibody-negative systemic lupus erythematosus and antiphospholipid syndrome. Severe respiratory failure, circulatory shock and acute renal failure necessitated artificial ventilation, inotropic and vasopressor therapy, and continuous venovenous haemofiltration. A tentative diagnosis of haemorrhagic lupus pneumonitis or pulmonary manifestation of antiphospholipid syndrome was made. Lupus anticoagulant, IgG anticardiolipin and anti-beta2-glycoprotein I antibodies were positive. High-dose glucocorticoid, anticoagulation with heparin, plasmapheresis and cyclophosphamide improved her clinical condition. Despite this, the patient died several days later of spontaneous intracranial haemorrhage. This case illustrates the uncommon manifestation of acute respiratory failure associated with antiphospholipid syndrome.

Acute Disease↗
PubMed2000

[Multiple primary carcinomas in patients with head and neck malignancies].

BACKGROUND: Multiple primary tumors can lead to diagnostic and therapeutical problems. In this study we surveyed frequency, localisation, diagnostic, chronologic and therapeutic aspects of multiple primary carcinomas in patients with head and neck tumors. PATIENTS AND METHODS: The data of 843 patients from the tumor registry of the ENT-clinic Aachen were retrospectively studied. RESULTS: Larynx (41.87%) and oropharynx (12.57%) were the main localisation of the first primary neoplasma. In 65 patients (7.71%) multiple primary tumors were observed. 24.6% of these tumors occurred synchronously. Preferential localisation of a second tumor were lung (20%), oral cavity (15.3%) and larynx (13.8%). 28.57% of the metachronous tumors were observed after more than five years. In 46.15% clinical complaints led to the suspicion of a second tumor. Panendoscopy was the most reliable diagnostic procedure. The survival rate and time was significantly reduced in patients with synchronous tumors. 3-year survival rate was 15% compared to 81% in patients with metachronous tumor appearance (p < 0.0001). CONCLUSION: Patients with head and neck tumors have a high incidence of multiple primary malignomas varying from the region of the first presentation of a malignant tumor. Concepts comprising surgery provide the highest survival rates. Because of the high incidence of metachronous carcinomas after five years found in this study, the authors regard a prolonged follow-up period as necessary.

Combined Modality Therapy↗
PubMed2000

Sensitive single-stage PCR using custom-synthesized internal controls.

A new approach for an internally controlled PCR was developed using a custom-synthesized oligonucleotide as the internal control. Three different PCR setups demonstrated the usefulness of this approach: (i) the addition of the respective internal control to samples containing ssDNA virus Parvo B19; (ii) the co-extraction of plasma samples and the respective internal control for the detection of the ssDNA virus TTV; and (iii) the addition of the respective internal control to a crude lysate of tail pieces for the genotyping of FVIII knockout mice, demonstrating that this approach is also applicable for dsDNA.

Animals↗