Dynamo Enhancement and Mode Selection Triggered by High Magnetic Permeability.

We present results from consistent dynamo simulations, where the electrically conducting and incompressible flow inside a cylinder vessel is forced by moving impellers numerically implemented by a penalization method. The numerical scheme models jumps of magnetic permeability for the solid impellers, resembling various configurations tested experimentally in the von Kármán sodium experiment. The most striking experimental observations are reproduced in our set of simulations. In particular, we report on the existence of a time-averaged axisymmetric dynamo mode, self-consistently generated when the magnetic permeability of the impellers exceeds a threshold. We describe a possible scenario involving both the turbulent flow in the vicinity of the impellers and the high magnetic permeability of the impellers.

Patient-individual local SAR determination: in vivo measurements and numerical validation.

Tissue heating during magnetic resonance measurements is a potential hazard at high-field MRI, and particularly, in the framework of parallel radiofrequency transmission. The heating is directly related to the radiofrequency energy absorbed during an magnetic resonance examination, that is, the specific absorption rate (SAR). SAR is a pivotal parameter in MRI safety regulations, requiring reliable estimation methods. Currently used methods are usually based on models which are neither patient-specific nor taken into account patient position and posture, which typically leads to the need for large safety margins. In this work, a novel approach is presented, which measures local SAR in a patient-specific manner. Using a specific formulation of Maxwell's equations, the local SAR is estimated via postprocessing of the complex transmit sensitivity of the radiofrequency antenna involved. The approximations involved in the proposed method are investigated. The presented approach yields a sufficiently accurate and patient-specific local SAR measurement of the brain within a scan time of less than 5 min.

Toward individualized SAR models and in vivo validation.

The specific absorption rate (SAR) is a limiting constraint in sequence design for high-field MRI. SAR estimation is typically performed by numerical simulations using generic human body models. This entails an intrinsic uncertainty in present SAR prediction. This study first investigates the required detail of human body models in terms of spatial resolution and the number of soft tissue classes required, based on finite-differences time-domain simulations of a 3 T body coil. The numerical results indicate that a resolution of 5 mm is sufficient for local SAR estimation. Moreover, a differentiation between fatty tissues, water-rich tissues, and the lungs was found to be essential to represent eddy current paths inside the human body. This study then proposes a novel approach for generating individualized body models from whole-body water-fat-separated MR data and applies it to volunteers. The SAR hotspots consistently occurred in the arms due to proximity to the body coil as well as in narrow regions of the muscles. An initial in vivo validation of the simulated fields in comparison with measured B(1)-field maps showed good qualitative and quantitative agreement.

[Three case reports of frostbite. Management and literature]. / Drei Fallberichte über Erfrierungen. Management und Literatur.

Due to social and demographic changes as well as new leisure activities, the number of frostbite injuries in the general population is on the increase. Because the injuries are primarily located on the hands and feet the consequences for those concerned are devastating. We provide help in grading and introduce concrete therapeutic regimes for frostbite which are illustrated by three case reports from our clinical experience with varying risk profiles.

[Lipoma and atypical lipomatous tumor within the same neoplasia: Evidence for a continuous transition]. / Lipom und atypischer lipomatöser Tumor innerhalb einer Neoplasie: Hinweis für einen kontinuierlichen Ubergang.

The case of a lipomatous tumor with a predominant lipoma component and transition to an atypical lipomatous tumor is presented. A deep-seated soft tissue tumor of the right thigh with a maximum size of 14 cm was resected in a 70-year-old female patient. Corresponding to a comparable macroscopic aspect, the lesion revealed the histological features of an ordinary lipoma without atypia in about 80% of the specimen. In the remaining portion (approximately 20%) histopathology showed an atypical lipomatous tumor (ALT, lipoma-like subtype). Immunohistochemistry for MDM 2 and CDK4 revealed no immunoreactivity in the lipoma component, but within the ALT component. Interphase dual-color fluorescence in situ hybridization showed no amplification of the MDM 2 gene and rarely CDK4 gene amplification within the lipoma component, but high level amplification of MDM 2/CDK4 gene in the ALT area, further supporting the morphologically based diagnosis of a lipomatous tumor including areas of a true lipoma and ALT. This case underlines the concept of a continuous stepwise development of lipomatous soft tissue tumors from benign to malignant counterparts as a biological continuum.

[Gardner fibroma: case report and discussion of a new soft tissue tumor entity]. / Gardner-Fibrom: Eine neue mesenchymale Tumorentität als Indikatorläsion.

Gardner fibroma represents a rare and recently described soft tissue tumor entity in children and young adults. It consists of haphazardly arranged coarse and hyalinized collagen fibers combined with loosely arranged bland spindle and fibroblastic cells. The case of a 13-year-old male patient with Gardner fibroma and osteoma and multicentric desmoid type fibromatosis in his mother is presented with detection of a (heterozygotic) germline mutation of the APC gene leading to a de novo stop codon (deletion of base pairs 5033-5036). FISH analysis revealed a structural loss of heterozygosity (LOH) in the APC gene on chromosomal locus 5q21 in one out of five analysed desmoids of the mother, no LOH of APC gene in the Gardner fibroma. Gardner fibroma in children and young adults may serve as an indicator lesion for familial adenomatous polyposis (FAP), Gardner syndrome, a familial desmoid type fibromatosis without other manifestations of APC or a new APC gene mutation. For the clinician, this diagnosis should be commented upon accordingly by the surgical pathologist. As the result of a detected APC gene mutation, continuous follow-up for the development of colorectal tumors and desmoid type fibromatosis as well as a familial screening for FAP is recommended.

[Identification of genes over-expressed in myxoid/round cell liposarcoma. DNA microarray analysis and immunohistochemical correlation]. / Identifikation überexprimierter Gene in myxoid-rundzelligen Liposarkomen. DNA-Mikroarray-Analyse und immunhistochemische Korrelation.

Myxoid/round cell liposarcoma are characterized by typical chromosomal translocations. This genetic alteration might result in specific gene-expression profiles in this tumor entity. To identify over-expressed genes in myxoid/round cell liposarcoma DNA microarray analysis was performed on four tumors and four samples of adult fat tissue. Genes ret, cdk4, cyclin D2 and c-myc showed over-expression by means of microarray analysis and Northern blotting. Immunohistochemistry demonstrated cytoplasmic localization of associated proteins in 36 different tumors. The localization of ret was seen in endothelial cells of plexiform vasculature in addition to its accumulation in tumor cells (25% of cases). The results show an over-expression of cdk4, cyclin D2, c-myc and ret on both the transcriptional and protein level in myxoid/round cell liposarcoma. For cyclin D2 and ret this finding has not been reported in this tumor type. The increase of ret on transcriptional level might be explained by its expression in endothelium in intratumoral plexiform blood vessels. For the molecular pathogenesis of myxoid/round cell liposarcoma our findings imply the involvement of these four genes in the deregulation of the cell cycle, especially as cdk4 and cyclin D2 are target genes of c-myc.

[Flexor tendon injuries of the hand]. / Beugesehnenverletzungen der Hand.

Flexor tendon injuries of the hand are relatively rare but pose significant challenges to both physician and patient. A thorough clinical evaluation enables flexor tendon lacerations to be identified and classified. The flexor tendons of the hand are divided into five anatomic zones (from distal to proximal). Diagnostics, treatment and prognosis may differ depending on which zone is affected. Early, careful and proficient management is needed to ensure good functional outcomes. Various factors influence the outcome, including location, mechanism of injury, presence of concomitant injuries, time of surgery, quality of tendon repair and the rehabilitation protocol. It is important to inform the patient about the importance of thorough rehabilitation and possible complications. Postoperative scarring and adhesions, infections and secondary tendon ruptures due to insufficient primary repairs are especially challenging and potentially necessitate a lengthy and strenuous secondary repair and rehabilitation process.

Effects of maleimide-polyethylene glycol-modified human hemoglobin (MP4) on tissue necrosis in SKH1-hr hairless mice.

OBJECTIVE: Tissue hypoxia after blood loss, replantation and flap reperfusion remains a challenging task in surgery. Normovolemic hemodilution improves hemorheologic properties without increasing oxygen carrying capacity. Red blood cell transfusion is the current standard of treatment with its attendant risks. The aim of this study was to investigate the potential of the chemically modified hemoglobin, MP4, to reduce skin flap necrosis and its effect on selected blood markers and kidneys. MATERIALS AND METHODS: Tissue ischemia was induced in the ear of hairless mice (n=26). Hemodilution was performed by replacing one third of blood volume with the similar amount of MP4, dextran, or blood. The extent of non-perfused tissue was assessed by intravital fluorescent microscopy. RESULTS: Of all groups, MP4 showed the smallest area of no perfusion (in percentage of the ear +/- SEM: 16.3% +/- 2.4), the control group the largest (22.4% +/- 3.5). Leukocytes showed a significant increase in the MP4 and dextran group (from 8.7 to 13.6 respectively 15.4*109/l). On histology no changes of the kidneys could be observed. CONCLUSION: MP4 causes an increase of leukocytes, improves the oxygen supply of the tissue and shows no evidence of renal impairment.

[Complex regional pain syndrome type II or psychogenic painful finger contracture?]. / CRPS Typ II oder psychogene schmerzhafte Fingerkontraktur?

The case is described of a 45-year-old man with fixed contracture of the proximal interphalangeal joints (digits III-IV) after a stab wound injury in the forearm with subsequent compartment syndrome and partial ulnar injury. Despite neurographic recovery there was permanent contracture during rehabilitation, which was classified as psychogenic. Differential diagnostic aspects of this assumption will be discussed on the basis of clinical criteria as well as 3-phase skeleton scintigraphy and MRT for differentiation between complex regional pain syndrome (CRPS) type II and other posttraumatic changes. Readers are encouraged to make their own diagnosis on the basis of the clinical findings and to discuss the case online (http://www.blogs.springer.com/derschmerz).

[Stump retention and extension on the lower extremity]. / Stumpferhalt und Stumpfverlängerung an der unteren Extremität.

Despite new techniques and better health programs in western industrialized nations, the numbers of amputations on the lower extremity remain constant. Approximately 100,000 amputations are performed annually in the U.S. and about 10,000 in Germany, more than 90% for gangrene resulting from ischemia and/or infection. Micro- and macroangiopathic changes in diabetes are the major cause of ischemia in the leg. The preservation of limb length and construction of an end bearing stump are important criteria for the functional outcome after amputation. Especially in trauma and tumor patients with "planned" amputations, all effort should be made to achieve an end bearing stump with sufficient length respectively an amputation level that is suitable for orthosis instead of prosthetic supplementation. After amputation, an interdisciplinary approach is mandatory to achieve sufficient soft tissue coverage or stump distalization. In case of insufficient bearing ability of the stump, various reconstructive possibilities must be considered to assure optimal outcome.

[Unclear soft-tissue tumor]. / Weichteiltumor unklarer Dignität.

Cystic necrotization with liquefaction and calcification of muscle tissue is a rare late sequel of compartmental syndrome. Diagnosis and treatment of this clinical picture is still a problem. In the literature, various therapeutic approaches are described such as incision, needle decompression, and complete compartmental debridement. We report a case in which cystic degradation and liquefaction of three compartments developed 51 years after a complete fracture of the tibia. The patient was treated by radical compartmental resection. No postoperative complication was noted, and almost no functional loss occurred.

[Crossover extremity transfers. Limb salvage in amputations with segmental defects]. / Heterotope Replantationen. Konzepte zum Extremitätenerhalt bei Mehrfachamputationen.

Clinical conditions in which crossover extremity transfer should be considered are rare. In the case of bilateral amputation associated with extensive proximal segmental injury, ectopic implantation could be an additional concept for two-stage limb salvage. If replantation is impossible due to segmental damage of the amputated part, at least uninvolved tissue should be harvested for stump lengthening or improving soft-tissue at the ends. The case of a 34-year-old man with segmental amputation of the left forearm and left lower leg and mutilated amputation of the right hand caused by a train accident is presented. Limb salvage was performed by cross-hand replantation and modified rotationplasty of the left foot as a stump lengthening procedure.

Recovery of mechanical detection thresholds after direct digital nerve repair versus conduit implantation.

The purpose of this study was to assess sensory and functional nerve recovery after digital nerve injury in patients with an end-to-end suture (S) or with implantation of a collagen conduit (C) to bridge a nerve gap. Fifteen S and 11 C with a follow-up of 6-36 months and 28 healthy control participants were enrolled. Methods of assessments were quantitative sensory testing, the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH), range of motion and the painDetect questionnaire. After both procedures, sensory profiles showed largely recovered function of C and Aδ fibres but severe loss of Aß-fibre function leading to increased mechanical detection thresholds. There was only minimal allodynia. Severe pain was absent. Patients with conduits reported more functional impairment, especially in work performance, which correlated with the assessed loss of Aß-fibre function. LEVEL OF EVIDENCE: III.

[Differential diagnosis of "sterile" phlegmonous hand infections]. / Differenzialdiagnose "steriler" phlegmonöser Entzündungen der Hand.

INTRODUCTION: Bacterial infections represent a large proportion of emergencies in hand surgery. In some cases, pyoderma gangrenosum and mycobacterial infection may present with the same symptoms of swelling, pain, and purulent secretion. In these cases, operative treatment would be harmful. Therefore two cases-pyoderma gangrenosum and tuberculosis-are presented here in relation to common bacterial hand infection. METHODS: Using two case reports of diseases that only rarely affect the hands, their relevance to differential diagnosis is shown with reference to the literature. RESULTS: In both cases, we found clinical symptoms of bacterial hand infection with negative bacterial smear tests. After several debridements, pyoderma gangrenosum of the dorsum of the hand was diagnosed in one patient after pyodermiform lesions at the thigh and the nasal septum were detected and pre-existing colitis ulcerosa was taken into consideration. Corticoid therapy induced complete remission. The second patient with similar clinical symptoms had been operated on at another hospital several times before being transferred to our institution. The presumptive diagnosis of pyoderma gangrenosum was made, and under treatment with prednisone the symptoms quickly improved. After 2 weeks, the wound conditions and the patient's condition rapidly worsened. Following amputation at the upper arm level, the patient died of septic multiple organ failure. Autopsy studies revealed tuberculous sepsis originating from the hand. DISCUSSION: Patient history should be evaluated carefully because of its value to correct diagnosis. In case of negative smear tests, especially from immunocompromised, elderly patients and in patients with a history of pulmonary tuberculosis, Ziehl-Neelsen staining should be obtained. In case of multilocular affection or pre-existing chronic inflammatory bowel disease, the presumptive diagnosis of pyoderma gangrenosum can be confirmed by biopsies from the lesions margin. In both cases, unnecessary traumatizing operations could thus be avoided and treatment optimized.

[Desmoplastic neurotropic melanoma. Diagnosis and therapeutic procedures for a rare clinical entity]. / Spindelzelliges desmoplastisches Melanom. Ein seltenes Krankheitsbild--Diagnostik und therapeutisches Vorgehen.

Desmoplastic neurotropic melanoma is an exceedingly rare variant of the malignant melanomas. Since the initial description, only about 500 cases have been reported in the literature. These melanomas mostly occur on the head, neck, and face, and a wide local excision of the tumor is probably the most important prognostic factor. Therefore, in most cases the tumor resections result in large tissue defects. To gain a good cosmetic result, tissue movement using flaps or grafts will most likely be required to cover the defect. In this paper, a 79-year-old patient with a basal cell carcinoma and desmoplastic melanoma on the scalp is described, and the therapeutic procedure is discussed.

[Otto Hilgenfeldt (1900 to 1983)--an unusual approach for finger reconstruction]. / Otto Hilgenfeldt (1900 bis 1983)--Ein ungewöhnliches Verfahren zum Fingerersatz.

Reconstructive surgery of detached extremities, especially fingers, has a long historical tradition. The first clinically correctly documented cases go back to the 19th century. During the first and second world wars numerous reports appeared about the surgical care of war victims. Pioneering innovative surgical methods were developed by especially motivated surgeons for the reconstruction of these disfiguring war injuries in Europe. Because of these particular circumstances and the prevailing revolutionary spirit, many innovations in surgery were developed. The report of Otto Hilgenfeldt (1950) described his unusual approach in reconstructing a finger by using the great toe.

[Intraosseous Tophaceous Gout of the Hand: Case Report and Literature Review]. / Intraossäre Gichterkrankung der Hand: Falldarstellung und Literaturübersicht.

We report on an intraosseous gout manifestation in the middle phalanx of the left index finger of a 54-year-old patient.

Arthroscopic treatment for ulnar-sided TFCC-tears.

OBJECTIVE: Ruptures of ulnar-sided triangular fibrocartilaginous complex (TFCC) often occur in cases of trauma. Golden standard for diagnosis is the arthroscopy of the wrist. TFCC lesions are classified according to their location if traumatic in origin or if degenerative according to their severity. MATERIALS AND METHODS: Recent literature has focused on the ruptures of ulnar-sided triangular fibrocartilaginous complex. This article describes conservative, operative and arthroscopic surgical techniques to reconstruct the triangular fibrocartilaginous complex and restore distal radioulnar joint stability. RESULTS: The main therapeutic goal should be the stabilization of the DRUJ by reattachment of the torn ligaments in ulnar-sided ruptures to the deep fibers in the fovea. This reinsertion can be performed by transosseous suture, a suture anchor or open. CONCLUSION: Central TFCC tears are typically located close to the sigmoid notch of the radius and are either traumatic or degenerative in origin. While central TFCC lesions are usually treated by arthroscopic debridement using small joint punches or a bipolar high frequency system, the ulnar TFCC avulsions can also be refixed arthroscopically in different techniques.

New model for in vivo investigation after microvascular breakdown in burns: use of intravital fluorescent microscopy.

BACKGROUND: The breakdown of skin microcirculation is assumed to play a key role in the pathophysiology after burn injury. The aim of the present study was to develop a burn model, which allows repetitive quantitative in vivo analysis of the microcirculation after a burn injury, focusing on the interaction between leukocytes and the endothelium. MATERIALS AND METHODS: Experiments were carried out on male hairless mice. Deep partial thickness burns were inflicted with a no-touch-technique to the ears. Intravital fluorescent microscopy in combination with FITC-dextran as a plasma marker was used to assess microcirculatory parameters. Leukocytes were stained with rhodamine 6G. Preburn baseline data was obtained before as well as 1, 3, 7 and 14 days subsequent to the burn injury. RESULTS: The non-perfused area decreased significantly over the observed period and perfusion was almost completely restored at day 14. The functional vessel density was characterized by reduction of perfused vessels immediately after burn and an increase after 24h. Leukocyte endothelium interaction significantly increased immediately after injury; baseline values were reached 1 day later. The extravasation of the plasma marker into the surrounding tissue increased immediately after burn, decreased at day 1 and remained at this level during the following observation time. The venular as well as the arterial blood flow increased immediately subsequent to the burn injury, decreased after 1 day and reached baseline values at day 3. CONCLUSION: The presented burn model allows quantitative assessment of the dynamics of microcirculatory disturbances after thermal trauma by high quality visualization of both plasma stained microvessels and leukocyte-endothelium interaction.