Infrared Parallaxes of Young Field Brown Dwarfs and Connections to Directly Imaged Gas-Giant Exoplanets

We have measured high-precision infrared parallaxes with the Canada-France-Hawaii Telescope for a large sample of candidate young (approximate to 10-100 Myr) and intermediate-age (approximate to 100-600 Myr) ultracool dwarfs, with spectral types ranging from M8 to T2.5. These objects are compelling benchmarks for substellar evolution and ultracool atmospheres at lower surface gravities (i.e., masses) than most of the field population. We find that the absolute magnitudes of our young sample can be systematically offset from ordinary (older) field dwarfs, with the young late-M objects being brighter and the young/dusty mid-L (L3-L6.5) objects being fainter, especially at J band. Thus, we conclude the "underluminosity" of the young planetary-mass companions HR 8799b and 2MASS J1207-39b compared to field dwarfs is also manifested in young free-floating brown dwarfs, though the effect is not as extreme. At the same time, some young objects over the full spectral type range of our sample are similar to field objects, and thus a simple correspondence between youth and magnitude offset relative to the field population appears to be lacking. Comparing the kinematics of our sample to nearby stellar associations and moving groups, we identify several new moving group members, including the first free-floating L dwarf in the AB Dor moving group, 2MASS J0355+11. Altogether, the effects of surface gravity (age) and dust content on the magnitudes and colors of substellar objects appear to be degenerate. (C) 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Recurrent giant cell tumor of long bones: analysis of surgical management

Treatment of giant cell tumor of bone (GCT) often is complicated by local recurrence. Intralesional curettage is the standard of care for primary GCTs. However, there is controversy whether intralesional curettage should be preferred over wide resection in recurrent GCTs.

Giant cell tumor of bone: risk factors for recurrence

Many surgeons treat giant cell tumor of bone (GCT) with intralesional curettage. Wide resection is reserved for extensive bone destruction where joint preservation is impossible or when expendable sites (eg, fibular head) are affected. Adjuvants such as polymethylmethacrylate and phenol have been recommended to reduce the risk of local recurrence after intralesional surgery. However, the best treatment of these tumors and risk factors for recurrence remain controversial.

Measurement of ventilation and cardiac related impedance changes with electrical impedance tomography

Introduction Electrical impedance tomography (EIT) has been shown to be able to distinguish both ventilation and perfusion. With adequate filtering the regional distributions of both ventilation and perfusion and their relationships could be analysed. Several methods of separation have been suggested previously, including breath holding, electrocardiograph (ECG) gating and frequency filtering. Many of these methods require interventions inappropriate in a clinical setting. This study therefore aims to extend a previously reported frequency filtering technique to a spontaneously breathing cohort and assess the regional distributions of ventilation and perfusion and their relationship. Methods Ten healthy adults were measured during a breath hold and while spontaneously breathing in supine, prone, left and right lateral positions. EIT data were analysed with and without filtering at the respiratory and heart rate. Profiles of ventilation, perfusion and ventilation/perfusion related impedance change were generated and regions of ventilation and pulmonary perfusion were identified and compared. Results Analysis of the filtration technique demonstrated its ability to separate the ventilation and cardiac related impedance signals without negative impact. It was, therefore, deemed suitable for use in this spontaneously breathing cohort. Regional distributions of ventilation, perfusion and the combined ΔZV/ΔZQ were calculated along the gravity axis and anatomically in each position. Along the gravity axis, gravity dependence was seen only in the lateral positions in ventilation distribution, with the dependent lung being better ventilated regardless of position. This gravity dependence was not seen in perfusion. When looking anatomically, differences were only apparent in the lateral positions. The lateral position ventilation distributions showed a difference in the left lung, with the right lung maintaining a similar distribution in both lateral positions. This is likely caused by more pronounced anatomical changes in the left lung when changing positions. Conclusions The modified filtration technique was demonstrated to be effective in separating the ventilation and perfusion signals in spontaneously breathing subjects. Gravity dependence was seen only in ventilation distribution in the left lung in lateral positions, suggesting gravity based shifts in anatomical structures. Gravity dependence was not seen in any perfusion distributions.

Giant Cardiac Fibroma: An Unusual Cause of Failure to Thrive

Cardiac fibromas are extremely rare in the general pediatric population and may present with a wide spectrum of clinical signs, including life-threatening arrhythmias and sudden death. We report a 14-month-old boy who presented with failure to thrive as the only symptom. Echocardiography showed a large cardiac fibroma in the right ventricle. Cardiac magnetic resonance imaging confirmed the diagnosis. After complete surgical tumor resection, the boy showed normal catch-up growth. This case underlines the diversity of clinical features of cardiac tumors, which implies that they should be considered early in the differential diagnosis of infants with failure to thrive.

Giant cell glioblastoma in the cerebrum of a pembroke welsh corgi

A 6-year-old, neutered female Pembroke Welsh corgi was presented with a 1-month history of ataxia and panting. The clinical signs progressed until the dog became anorexic, obtunded and exhibited circling to the left. At necropsy examination, a mass was detected in the left forebrain, impinging on the cribriform plate. Microscopically, the mass was composed of sheets of round to pleomorphic neoplastic cells with vacuolated cytoplasm. Nuclear atypia, anisocytosis and anisokaryosis were common. Numerous bizarre, multinucleated giant cells containing 60 or more nuclei and giant mononuclear cells were present. The matrix contained abundant reticulin. Immunohistochemistry revealed the neoplastic cells uniformly to express vimentin, and a small number of neoplastic cells expressed glial fibrillary acid protein. A diagnosis of giant cell glioblastoma was made. Although well recognized in man, this tumour has been documented rarely in the veterinary literature.

Structural plasticity of spines at giant mossy fiber synapses

The granule cells of the dentate gyrus give rise to thin unmyelinated axons, the mossy fibers. They form giant presynaptic boutons impinging on large complex spines on the proximal dendritic portions of hilar mossy cells and CA3 pyramidal neurons. While these anatomical characteristics have been known for some time, it remained unclear whether functional changes at mossy fiber synapses such as long-term potentiation (LTP) are associated with structural changes. Since subtle structural changes may escape a fine-structural analysis when the tissue is fixed by using aldehydes and is dehydrated in ethanol, rapid high-pressure freezing (HPF) of the tissue was applied. Slice cultures of hippocampus were prepared and incubated in vitro for 2 weeks. Then, chemical LTP (cLTP) was induced by the application of 25 mM tetraethylammonium (TEA) for 10 min. Whole-cell patch-clamp recordings from CA3 pyramidal neurons revealed a highly significant potentiation of mossy fiber synapses when compared to control conditions before the application of TEA. Next, the slice cultures were subjected to HPF, cryosubstitution, and embedding in Epon for a fine-structural analysis. When compared to control tissue, we noticed a significant decrease of synaptic vesicles in mossy fiber boutons and a concomitant increase in the length of the presynaptic membrane. On the postsynaptic side, we observed the formation of small, finger-like protrusions, emanating from the large complex spines. These short protrusions gave rise to active zones that were shorter than those normally found on the thorny excrescences. However, the total number of active zones was significantly increased. Of note, none of these cLTP-induced structural changes was observed in slice cultures from Munc13-1 deficient mouse mutants showing severely impaired vesicle priming and docking. In conclusion, application of HPF allowed us to monitor cLTP-induced structural reorganization of mossy fiber synapses.

Impedance-pH reflux patterns can differentiate non-erosive reflux disease from functional heartburn patients

Symptom association is important to distinguish non-erosive reflux disease [NERD; abnormal oesophageal acid exposure time (AET) and/or positive symptom association] from functional heartburn (FH; normal AET and negative symptom association). Asymptomatic patients during reflux monitoring are challenging as symptom association cannot be assessed.