Cystic tumor of the jugulodigastric triangle.
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Branchioma↗
Biomedical subjects
U Hahn
Publications and source records attributed to U Hahn.
Binding of TmHU to single dsDNA as observed by optical tweezers.
Optical tweezers are employed to study the action of the histone-like protein from Thermotoga maritima (TmHU) on DNA at a single molecule level. Binding and disruption of TmHU to and from DNA are found to take place in discrete steps of 4-5 nm length and a net binding enthalpy of about 16kBT. This is in reasonable agreement with a microscopic model that estimates the extension of the binding sites of the protein and evaluates the energetics mainly for bending of the DNA in the course of interaction.
Bacterial Proteins↗
Selection of RNase-resistant RNAs.
All RNA types are susceptible to ribonuclease (RNase) digestion, which might be a serious problem for several in vitro and in vivo applications. RNase resistance can be reached through chemical modifications or the selection of stable secondary structures via SELEX (systematic evolution of ligands by exponential enrichment). This chapter focuses on the selection of natural RNase-resistant RNAs, enriched by a selection process in the presence of RNase T1. Results of these investigations led to the identification of a particular structural motif, the tetraloop. Further applications could be the advised use of such motifs in order to reach higher stability of RNA molecules.
Animals↗
[Lecture disasters - and how to prevent them].
Presentations at medical conferences can sometimes confuse or compromise understanding of current topics. Although considerable time and financial costs may be taken to be present at such events, all too often one must go through inferior presentations that are poorly structured and do not contribute to one's understanding of the topic at hand. A good presentation is distinguishable by the clear intentions of the speaker to give a good lecture. The presenter has worked extensively with his topic and is familiar with the audience. The presentation has a clear structure and finishes with a take-home message. The speaker takes the listener from his previous level of knowledge to a new understanding. To do so, both voice and body language are used. The supporting slides are simple and direct, and not overloaded with information. The speech conforms exactly with the pre-determined time limit.
Audiovisual Aids↗
Disseminated mucormycosis in haematological patients: CT and MRI findings with pathological correlation.
Disseminated mucormycosis is a rare, mostly fatal infectious complication in immunocompromised haematological patients. The purpose of our study was to describe the multiorgan manifestations of disseminated mucormycosis documented at CT and MRI in four patients and correlate these with the pathological findings and patient outcome. Irrespective of the site of infection, infarction or haemorrhage are the constant features of invasive mycosis. Identification of one or both of these two major imaging findings in immunocompromised patients should be regarded as an indicator of possible infection by angiotropic fungi, including the genre Mucorales.
Adult↗
The semantics of procedures and diseases in SNOMED CT.
OBJECTIVES: SNOMED CT is emerging as a reference terminology for the entire health care process. It claims to be founded on logic-based modelling principles. In this article, we analyze a special encoding scheme for diseases and procedures in SNOMED CT, the so-called relationship groups (RGs), which had been devised to avoid ambiguities in definitions. METHODS: We reformulate SNOMED CT's relationship groups in the format of description logics in order to check whether RGs serve the needs they were designed for. RESULTS: We show that a considerable proportion of relationship groups represent hidden mereological relations. We also report discrepancies encountered between the defined semantics of many SNOMED CT terms and their intuitive meaning, as well as inconsistencies detected between the definition of various complex composed terms and the definition of their top-level parents. CONCLUSIONS: We formulate recommendations for improving SNOMED CT by replacing most occurrences of relation groups by formally more adequate "part-of" relations.
Anatomy↗
Purine activity of RNase T1RV is further improved by substitution of Trp59 by tyrosine.
Ribonuclease T1 is an enzyme that cleaves single-stranded RNA with high specificity after guanylyl residues. Although this enzyme is a very good characterized protein with respect to structure and enzymatic function, we were only recently successful in generating RNase T1-RV, a variant where the specificity was changed from guanine to purine. As this change of substrate specificity was made at the cost of activity, the aim was now to further improve the overall activity of the enzyme. Therefore, we have substituted the tryptophan in position 59 by tyrosine. This substitution led to an increase of enzymatic activity in comparison to variant RV to 425%. As the extent of this enhancement is unique so far we have crystallized and analyzed the structure of this variant in order to get more insights into the reasons for this. Here, we present the crystal structure of this so-called RNase T1-R2 at 2.1A resolution. The structure was determined by molecular replacement using the coordinates of the RV variant (PDB entry: 1Q9E). The data were refined to an R-factor of 18.7% and R(free) of 24%, respectively. The asymmetric unit contains three molecules and the crystal packing is very similar to that of variant RV.
Amino Acid Substitution↗
[Multistep surgery for spondylosyndesis. Treatment concept of destructive spondylodiscitis in patients with reduced general condition].
OBJECTIVE: Retrospective assessment of multistage surgery in the treatment of progressive spondylodiscitis in patients with critical physical status. PATIENTS: A total of 34 patients (mean age 58.6 years) with 37 progressive spondylodiscitis foci and destruction of one to three vertebral segments (1.9 mean) were recorded within an 8-year period. Time between first complaints and operative treatment was 3 months (mean). Preoperative health status was critically reduced in 11 patients (ASA IV) and poor general condition (ASA III) was seen in 23 patients when vital indication was seen preoperatively. Considerable systemic disease (n=31), further infection focus (n=18), and nosocomial trauma (n=5) were causally related. Spondylodiscitis was seen more frequently in the lumbar (n=20) and thoracolumbar than in the thoracic (n=10) and cervical spine (n=1). Staphylococcus aureus was detectable from operative specimens and hemoculture in 15 cases, MRSA in 6 of these. METHODS: In cases of monosegmentary involvement (n=7) ventral debridement, biopsy, and application of antibiotic chains were followed by autologous interbody bone grafting in a second stage operation. In 29 cases with destruction of two (n=27) and three (n=3) segments, posterior instrumentation including laminectomy in 4 patients was completed by anterior debridement and application of antibiotic chains during a first surgical intervention. After stabilization of physical condition and having reached a macroscopically indisputable implant bed, the ventral fusion with autologous interbody bone grafting or cage in combination with a plate or internal fixation system was performed as the last of several surgical steps. RESULTS: No case of perioperative mortality was observed. Intensive care continued 9.1 days and hospitalization 49.5 days (mean). During a 37.6-month follow-up two late recurrences were observed. CONCLUSION: A multistep surgical procedure under protection of dorsal instrumentation can limit perioperative mortality in patients in critical general condition by avoiding an extended one stage dorsoventral spondylodesis. After eradication of further infection foci and stabilization of physical condition, ventral instrumentation is completed under elective conditions.
Adult↗
Aortic root remodeling: functional MRI as an accurate tool for complete follow-up.
BACKGROUND: After aortic valve-sparing procedures patients should be evaluated regularly because of the risk for further disease progression in the remaining aorta as well as recurrent aortic insufficiency. The purpose of this study was to evaluate the potential of functional MRI as a single examination for complete follow-up of these patients. METHODS: Twenty-two patients with a mean age of 54 years (range 30 - 66) were prospectively examined at 1, 12, 24, 36, and 74 months postoperatively, following a Yacoub aortic root remodeling operation, using a 1.5 T MRI. The original disease was chronic aneurysm of the ascending aorta or root in 17, chronic dissection in 3, and acute dissection in 2 patients. Transverse graft diameters, regurgitant fraction, LVEDV, and cardiac index were measured using cine MRI. Results were compared to spiral computed tomography and transthoracic color Doppler echocardiography. Mean time of follow-up was 24.9 months and ranged from 1 to 74 months. RESULTS: There were 2 re-operations, 2 years after primary surgery, due to high aortic insufficiency. CT and MRI measurements of graft diameters correlated well (p = 0.4544). Mean graft diameter (mean +/- SD) was 30 +/- 3.7, 33 +/- 3.4, 36.5 +/- 1.5, 37 +/- 2.8, and 38.3 +/- 2.8 mm at 1, 12, 24, 36, and 74 months, respectively, indicating a significant increase of graft diameter (p < 0.0001). Mean regurgitant fraction as determined by MRI was 14 +/- 7, 12 +/- 9, 13 +/- 9, 15 +/- 7, and 14 +/- 9 % at 1, 12, 24, 36, and 74 months, respectively. Flow based grading of aortic insufficiency by MR imaging correlated well with color Doppler echocardiography (p < 0.0001). CONCLUSIONS: MRI provides an excellent, noninvasive, comprehensive tool for follow-up after valve-sparing aortic root reconstruction. The determination of regurgitant fraction, ventricular dimensions and functions, and graft diameters allows standardized imaging protocols with a high reproducibility, which may lead to this technique being favored for the follow-up of patients after aortic root remodeling.
Adult↗
Perioperative monitoring of flow and patency in native and grafted internal mammary arteries using a combined MR protocol.
The objective of this study was to evaluate graft flow (f) and patency (p) in patients with internal mammary artery (f,p) and venous (p only) grafts using a combined MR protocol with phase-contrast technique and MR angiography. 42 patients with 42 left internal mammary artery (LIMA) and 63 venous grafts were examined pre and 6 months post coronary artery bypass graft (CABG) surgery. Phase-contrast flow measurements were applied to the IMA. Post-operatively, a contrast enhanced MR angiogram was performed to assess bypass patency. LIMA/venous grafts were occluded in 3/42 and 13/63, respectively. Flow in LIMA decreased from 19.4+/-10.4 ml min(-1) m(-2) pre-operatively to 13.4+/-9.7 ml min(-1) m(-2) post-operatively (p<0.002). In contrast, flow in the native right IMA increased from 17.6+/-8.7 ml min(-1) m(-2) pre-operatively to 24.8+/-9.0 ml min(-1) m(-2) post-operatively (p<0.001). MRI allows a combined assessment of bypass patency and flow. This study protocol may be applicable to perioperative follow-up studies in patients after CABG surgery.
Aged↗
MorphoSaurus--design and evaluation of an interlingua-based, cross-language document retrieval engine for the medical domain.
OBJECTIVES: We propose an interlingua-based indexing approach to account for the particular challenges that arise in the design and implementation of cross-language document retrieval systems for the medical domain. METHODS: Documents, as well as queries, are mapped to a language-independent conceptual layer on which retrieval operations are performed. We contrast this approach with the direct translation of German queries to English ones which, subsequently, are matched against English documents. RESULTS: We evaluate both approaches, interlingua-based and direct translation, on a large medical document collection, the OHSUMED corpus. A substantial benefit for interlingua-based document retrieval using German queries on English texts is found, which amounts to 93% of the (monolingual) English baseline. CONCLUSIONS: Most state-of-the-art cross-language information retrieval systems translate user queries to the language(s) of the target documents. In contra-distinction to this approach, translating both documents and user queries into a language-independent, concept-like representation format is more beneficial to enhance cross-language retrieval performance.
Abstracting and Indexing↗
Spinal epidural abscess--a rare complication after epidural analgesia for labour and delivery.
We report a case of spinal epidural abscess formation after short-term epidural catheter placement for analgesia during labour and delivery. The patient was previously healthy and did not have any predisposing factors. Increasing back pain was the only complaint. A contrast-enhanced CT study on day 5 was inconclusive. Magnetic resonance imaging was performed and showed a large triangular-shaped abscess with adjacent inflammation of the paravertebral muscles. One day later, the patient developed a sensory deficit in the left lower limb. The neurological deficit completely resolved after surgical decompression and debridement, which was followed by antibiotic treatment.
Adult↗
[Multidirectional atlantoaxial instability of an os odontoideum in an adult].
Increasing neck pain in a 29 year old woman after a frontal car collision gave reason for a conventional x-ray that presented a traumatically displaced os odontoideum positioned at the top of the dens axis. No neurological defect was seen. Dynamic flexion/extension film showed a movement to an atlantoaxial dislocation with a shift of the os odontoideum. The sclerotic structure of the corresponding bony surfaces was confirmed by computed tomography, whereas magnetic resonance imaging demonstrated a posttraumatic signal change in front of the base of dens axis and os odontoideum. Fusion was achieved by computed navigation with C1/C2 transfacetal screws as described by Magerl and interspinal fusion with a bicortical autologous iliac crest graft and a posterior tension band as described by Brooks. An exact positioning of screws past the asymmetric course of both arteria vertebrales was possible by navigation. The patient was free of pain 5 months after the fusion.
Adult↗
[Use of the injectable bone cement Norian SRS for tibial plateau fractures. Results of a prospective 30-month follow-up study].
Reduction of the depressed joint surface in tibial plateau fractures often leaves large cancellous bone defects. These metaphyseal voids are typically filled with autogenous bone grafts that can cause a significant donor site morbidity. The use of injectable bone cement offers the opportunity to support the reduced joint surface without bone grafting. The aim of this study was to evaluate the clinical and radiological outcome as well as the period of partial weight bearing after the use of Norian SRS in tibial plateau fractures. Twenty-one patients with a mean age of 48 years were included in this prospective trial. According to the AO/OTA Classification, there were seven fractures of type B2, ten B3, one C1, one C2, and two fractures of type C3. The period of partial weight bearing was 3.7 weeks. In 18 patients the follow-up was more than 24 months. After a mean follow-up of 30 months, the Lysholm score was 87.9 at mean. The radiological part of the Rasmussen score was excellent and good in eight cases each and fair in four cases. Soft tissue reactions due to the cement were not observed. On all radiographs taken 36 months after the operation the cement bloc was still visible. The results show that Norian SRS can be used to fill metaphyseal bone defects in tibial plateau fractures. Clinical and radiological results are comparable to those of fractures treated with autologous bone graft. The high compression strength allows early full weight bearing without the risk of secondary loss of reduction.
Adult↗
[Fulminant invasive fungal sinusitis in immunosuppressed hosts -- pathognomic presentation in MRI].
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Adult↗
[Glioblastoma multiforme of the optic nerve].
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Antineoplastic Agents↗
Long-term follow up of sequential mobilisation and autologous transplantation with CD34-selected cells in multiple myeloma: a multimodality approach.
BACKGROUND: Even after high dose chemotherapy (HDT) and autologous haemopoietic stem cell transplantation, the majority of patients with multiple myeloma eventually relapse. AIM: The aim of the present study was to study the -feasibility and outcome of delivering a regimen including in vivo and in vitro purging and double HDT in patients with multiple myeloma. METHODS: Thirty-four patients with advanced multiple myeloma were enrolled in a program of vincristine, doxorubicin and dexamethasone chemotherapy, high dose cyclophosphamide/granulocyte macrophage colony stimulating factor (GM-CSF) stem cell mobilisation, CD34 selection of harvested stem cells (in vitro purging), double HDT (cyclophosphamide/epirubicin in the first, busulphan/melphalan in the second) rescued by CD34(+)-selected cells, the second rescue using cells harvested following the first HDT (in vivo purging) and interferon maintenance. RESULTS: Forty-four per cent of patients completed the program. Fifty-three per cent of withdrawals were as a result of insufficient stem cells. This correlated to previous chemotherapy. Therapy-related mortality was 6%. CD34(+) selection achieved more than a 2-log reduction of CD38(++) cells; in vivo purging achieved 80%. Although similar numbers of CD34(+) cells were reinfused at both HDT, platelet recovery was slower after the second HDT. Additional complete remissions were achieved after each phase of therapy, 3% at the end of vincristine, doxorubicin and dexamethasone and 33% after completing planned HDT. Factors associated with longer overall survival included age less than 60 years (P = 0.044), serum beta-2-microglobulin below 3 micro gamma/L at entry (P = 0.042) and less than 2 months between the two HDT (P = 0.024). The only factor associated with a longer event-free survival was less than 2 months between HDT on study (P = 0.038). CONCLUSIONS: (i) dose intensification with two HDT delivered within 2 months might be associated with a better patient outcome, (ii) early mobilisation should be incorporated in multiple myeloma HDT programs and (iii) higher CD34(+) doses may be required for tandem transplants.
Adult↗
[Schwannoma of the geniculate ganglion].
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Adult↗