Shoe rim and shoe buckle pseudotumor of the ankle in elite and professional figure skaters and snowboarders: MR imaging findings

Objective: To review MR imaging of figure skaters and snowboarders presenting with painful soft-tissue swelling of the lateral supramalleolar region with a clinical provisional diagnosis of soft-tissue tumor. Design and patients: MR imaging was prospectively reviewed by two sub-specialized musculoskeletal radiologists. The findings were correlated with a second clinical review and examination of the shoe wear. The patients were four female athletes undergoing heavy training regimes, ranging in age between 16 and 25years. Two patients were elite figure skaters, and two were professional snowboarders. Three patients had unilateral masses with pain, and one patient presented with bilateral clinical findings. Results: MR imaging showed subcutaneous, focal soft-tissue masses of the supramalleolar region in five ankles at the same level above the ankle joint. MR imaging prompted a second clinical review and correlation with the shoe wear. The MR imaging findings correlated to the level of the shoe rim or shoe buckle in all patients, confirming the suspected MR imaging diagnosis of an impingement syndrome. All four sportswomen were training excessively, ignoring safety advice regarding training duration, timing of breaks, and shoe wear rotation. Conclusion: Ice skaters and snowboarders may present with persistent and disabling pain. On MR imaging, this corresponds to a focal soft-tissue abnormality, which may be due to subcutaneous fat impingement between the fibula and the shoe rim or shoe buckl

Optimal Alignment Sensing of a Readout Mode Cleaner Cavity

Critically coupled resonant optical cavities are often used as mode cleaners in optical systems to improve the signal to noise ratio (SNR) of a signal that is encoded as an amplitude modulation of a laser beam. Achieving the best SNR requires maintaining the alignment of the mode cleaner relative to the laser beam on which the signal is encoded. An automatic alignment system which is primarily sensitive to the carrier field component of the beam will not, in general, provide optimal SNR. We present an approach that modifies traditional dither alignment sensing by applying a large amplitude modulation on the signal field, thereby producing error signals that are sensitive to the signal sideband field alignment. When used in conjunction with alignment actuators, this approach can improve the detected SNR; we demonstrate a factor of 3 improvement in the SNR of a kilometer-scale detector of the Laser Interferometer Gravitational-wave Observatory. This approach can be generalized to other types of alignment sensors

Postpartum osteoporosis associated with proximal tibial stress fracture

A 33-year-old woman presented with acute nonspecific knee pain, 6months postpartum. MR imaging, computed tomography and radiography were performed and a proximal tibia plateau insufficiency fracture was detected. Bone densitometry demonstrated mild postpartum osteoporosis. To our knowledge these findings have not been described in this location and in this clinical setting. The etiology of the atraumatic fracture of the tibia is presumed to be due to a low bone mineral density. The bone loss was probably due to pregnancy, lactation and postpartum hormonal changes. There were no other inciting causes and the patient was normocalcemic. We discuss the presence of a postpartum stress fracture in a hitherto undescribed site in a patient who had lactated following an uncomplicated pregnancy and had no other identifiable cause for a stress fractur

Thermo-optic noise in coated mirrors for high-precision optical measurements

Thermal fluctuations in the coatings used to make high-reflectors are becoming significant noise sources in precision optical measurements and are particularly relevant to advanced gravitational wave detectors. There are two recognized sources of coating thermal noise, mechanical loss and thermal dissipation. Thermal dissipation causes thermal fluctuations in the coating which produce noise via the thermo-elastic and thermo-refractive mechanisms. We treat these mechanisms coherently, give a correction for finite coating thickness, and evaluate the implications for Advanced LIGO

Quantification and predictors of plasma volume expansion from mannitol treatment

Objective: To determine the effects of acute hypertonic mannitol infusion on intravascular volume expansion and to identify potential predictors of hypervolemia. Design: Measurements of plasma volume and volume regulatory hormones were performed in healthy volunteers before and over 90 min after acute infusion of 20 % mannitol solution in a therapeutic dose of 0.5 g/kg body weight, equalling an average infusion volume of 180 ml. Setting: Clinical research unit in an 800-bed teaching hospital in the eastern part of Switzerland. Participants: Eight normal male volunteers. Measurements and results: Baseline plasma volume was determined by the indocyanine green dye dilution technique. Serial plasma protein measurements were performed after mannitol infusion to calculate intravascular volume changes. Mannitol administration resulted in a plasma expansion that persisted for more than 90 min and peaked at 112 % of the baseline plasma volume 15 min after infusion. Concomitantly, an increase in systolic blood pressure and a fall in plasma sodium concentration occurred. Pharmacokinetic analyses of mannitol distribution and elimination revealed a close relation between plasma volume expansion and mannitol serum concentrations. While renin activity and aldosterone concentrations were suppressed proportionally to the intravascular volume increase, antidiuretic hormone was increased despite notable volume expansion and hyponatremia. Similarly, a rise in atrial natriuretic peptide was detected. Conclusions: Therapeutic doses of hypertonic mannitol cause substantial plasma volume expansion, resulting in increased blood pressure. Plasma volume expansion is related to mannitol serum concentrations and mannitol clearance determines the time required to restore normovolemia. ADH and ANP are potentially aggravating factors of mannitol-induced hyponatremi

The role of VEGF receptors in angiogenesis; complex partnerships

Abstract.: Vascular endothelial growth factors (VEGFs) regulate blood and lymphatic vessel development and homeostasis but also have profound effects on neural cells. VEGFs are predominantly produced by endothelial, hematopoietic and stromal cells in response to hypoxia and upon stimulation with growth factors such as transforming growth factors, interleukins or platelet-derived growth factor. VEGFs bind to three variants of type III receptor tyrosine kinases, VEGF receptor 1, 2 and 3. Each VEGF isoform binds to a particular subset of these receptors giving rise to the formation of receptor homo- and heterodimers that activate discrete signaling pathways. Signal specificity of VEGF receptors is further modulated upon recruitment of coreceptors, such as neuropilins, heparan sulfate, integrins or cadherins. Here we summarize the knowledge accumulated since the discovery of these proteins more than 20years ago with the emphasis on the signaling pathways activated by VEGF receptors in endothelial cells during cell migration, growth and differentiatio

Harris lines of the tibia across centuries: a comparison of two populations, medieval and contemporary in Central Europe

Objective: To determine the incidence of Harris lines in two medieval populations which inhabited the Canton of Berne, in Central Switzerland, and to compare the results with those of a contemporary population living in the same geographical area. A simplified method is described for measuring the age of the individual at the time of formation of Harris lines, with possible future applications. Design and patients: Radiographs of 112 well-preserved tibiae of skeletons of two medieval populations from the eighth to fifteenth centuries were reviewed for the incidence of Harris lines. The results were compared with those of 138 current patients living in the same geographic location in Central Switzerland. Age and gender of the medieval individual were determined using known anthropological methods. Age of bone at the time of formation of Harris lines was estimated according to the method of Maat. Results: Harris lines were found in 88 of 112 (80%) of the examined medieval skeletons and in 28 of 138 (20%) of the living individuals. Higher incidences of Harris lines were found at the age of 2years and at ages between 8 and 12years in both populations. No gender difference was found regarding the incidence of Harris lines. In both populations the occurrence of Harris lines was associated with certain diseases such as degenerative bone disease, trauma, osteoporosis, rheumatoid arthritis, peripheral vascular diseases, rickets and bony deformities. Conclusion: A high incidence of Harris lines was found in the medieval population, perhaps reflecting difficult living and hygienic conditions, but also the poor care and neglect of the children population. Measuring the age of the individual at the time of formation of Harris lines is simple and may have future clinical applications in the paediatric population for medico-legal purposes. The application of Harris lines as a marker in follow-up of osteoporosis may need further evaluatio

Feasibility of measuring the Shapiro time delay over meter-scale distances

The time delay of light as it passes by a massive object, first calculated by Shapiro in 1964, is a hallmark of the curvature of space-time. To date, all measurements of the Shapiro time delay have been made over solar-system distance scales. We show that the new generation of kilometer-scale laser interferometers being constructed as gravitational wave detectors, in particular Advanced LIGO, will in principle be sensitive enough to measure variations in the Shapiro time delay produced by a suitably designed rotating object placed near the laser beam. We show that such an apparatus is feasible (though not easy) to construct, present an example design, and calculate the signal that would be detectable by Advanced LIGO. This offers the first opportunity to measure space-time curvature effects on a laboratory distance scale.Comment: 13 pages, 6 figures; v3 has updated instrumental noise curves plus a few text edits; resubmitted to Classical and Quantum Gravit

Gremlin is a novel agonist of the major pro-angiogenic receptor VEGFR2

The bone morphogenic protein antagonist gremlin is expressed during embryonic development and under different pathologic conditions, including cancer. Gremlin is a proangiogenic protein belonging to the cystine-knot superfamily that includes transforming growth factor-β proteins and the angiogenic vascular endothelial growth factors (VEGFs). Here, we demonstrate that gremlin binds VEGF receptor-2 (VEGFR2), the main transducer of VEGF-mediated angiogenic signals, in a bone morphogenic protein-independent manner. Similar to VEGF-A, gremlin activates VEGFR2 in endothelial cells, leading to VEGFR2-dependent angiogenic responses in vitro and in vivo. Gremlin thus represents a novel proangiogenic VEGFR2 agonist distinct from the VEGF family ligands with implications in vascular development, angiogenesis-dependent diseases, and tumor neovascularization

A VEGF-A splice variant defective for heparan sulfate and neuropilin-1 binding shows attenuated signaling through VEGFR-2

Abstract.: The development of functional blood and lymphatic vessels requires spatio-temporal coordination of the production and release of growth factors such as vascular endothelial growth factors (VEGFs). VEGF family proteins are produced in multiple isoforms with distinct biological properties and bind to three types of VEGF receptors. A VEGF-A splice variant, VEGF-A165b, has recently been isolated from kidney epithelial cells. This variant is identical to VEGF-A165 except for the last six amino acids encoded by an alternative exon. VEGF-A165b and VEGF-A165 bind VEGF receptors 1 and 2 with similar affinity. VEGF-A165b elicits drastically reduced activity in angiogenesis assays and even counteracts signaling by VEGF-A165. VEGF-A165b weakly binds to heparan sulfate and does not interact with neuropilin-1, a coreceptor for VEGF receptor 2. To determine the molecular basis for altered signaling by VEGF-A165b we measured VEGF receptor 2 and ERK kinase activity in endothelial cells in culture. VEGF-A165 induced strong and sustained activation of VEGF receptor 2 and ERK-1 and −2, while activation by VEGF-A165b was only weak and transient. Taken together these data show that VEGF-A165b has attenuated signaling potential through VEGF receptor 2 defining this new member of the VEGF family as a partial receptor agonis