Intramuscular schwannoma: clinical and magnetic resonance imaging features

INTRODUCTION

Schwannomas that arise within the muscle plane are called intramuscular schwannomas. The low incidence of these tumours and the lack of specific clinical features make preoperative diagnosis difficult. Herein, we report our experience with intramuscular schwannomas. We present details of the clinical presentation, radiological diagnosis and management of these tumours.

METHODS

Between January 2011 and December 2013, 29 patients were diagnosed and treated for histologically proven schwannoma at the National University Hospital, Singapore. Among these 29 patients, eight (five male, three female) had intramuscular schwannomas.

RESULTS

The mean age of the eight patients was 40 (range 27–57) years. The most common presenting feature was a palpable mass. The mean interval between surgical treatment and the onset of clinical symptoms was 17.1 (range 4–72) months. Six of the eight tumours (75.0%) were located in the lower limb, while 2 (25.0%) were located in the upper limb. None of the patients had any preoperative neurological deficits. Tinel’s sign was present in one patient. Magnetic resonance (MR) imaging showed that the findings of split-fat sign, low signal margin and fascicular sign were present in all patients. The entry and exit sign was observed in 4 (50.0%) patients, a hyperintense rim was observed in 7 (87.5%) patients and the target sign was observed in 5 (62.5%) patients. All patients underwent microsurgical excision of the tumour and none developed any postoperative neurological deficits.

CONCLUSION

Intramuscular schwannomas demonstrate the findings of split-fat sign, low signal margin and fascicular sign on MR imaging. These findings are useful for the radiological diagnosis of intramuscular schwannoma.     

National Trends and Outcomes in Dialysis-Requiring Acute Kidney Injury in Heart Failure: 2002–2013

Background

Dialysis-requiring acute kidney injury (D-AKI) is a serious complication in hospitalized heart failure (HF) patients. However, data on national trends are lacking after 2002.

Leishmania-induced biphasic ceramide generation in macrophages is crucial for uptake and survival of the parasite

The initial macrophage-Leishmania donovani interaction results in the formation of membrane platforms, termed lipid rafts, that help in the entry of the parasite. Therefore, it is imperative that the parasite designs a strategy to modulate its uptake and survival within the macrophages. Herein, we report Leishmania-triggered biphasic ceramide generation. In the first phase, L. donovani promastigotes induce activation of acid sphingomyelinase (ASMase), which catalyzes the formation of ceramide from sphingomyelin. Inhibition of ASMase resulted in reduced uptake and infection with the parasite. In the second phase, de novo synthesis generates ceramide that reduces the cellular cholesterol level and displaces the cholesterol from the membrane, leading to enhanced membrane fluidity, disruption of rafts, and impaired antigen-presentation to the T cells. The results reveal a novel role for ceramide in the perspective of L. donovani infection and help formulate an antileishmanial strategy that can possibly be applied to other intracellular infections as well.     

A DFT study to probe homo-conjugated norbornylogous bridged spacers in dye-sensitized solar cells: an approach to suppressing agglomeration of dye molecules

This work reports a sigma-bridged framework as spacers to design new dye-sensitized solar cells. The norbornylogous bridged spacer can avoid π–π aggregation of dye molecules on the semiconductor surface in DSSCs. These sesquinorbornatrienes are known to exhibit electron propagation through the interaction of sigma and π orbitals via through bond (OITB) and through space (OITS) mechanisms. Density functional theory (DFT) calculations performed with these spacers and a modelled simple donor unit like N,N-dimethylamine and cyanoacrylic acid as the anchoring group showed significant results with the requisite optical parameters for DSSCs. The newly designed dyes have shown comparable or better optical properties compared to the reference dye molecule with π-conjugated thiophene spacer units. The ΔG_injection, V_OC and μ_normal values calculated for the designed dyes were found to be higher than those of the reference system. The trans-sesquinorbornatriene system spacer (6-D) showed a V_OC of 3.3 eV, ΔG_injection of 2.4 eV and oscillatory strength (f) of 0.96. The total and partial density of states indicates a good communication between the valence and conduction band for the designed dyes. Transition density matrix results suggest that the exciton dissociation in the excited state is sufficiently high to overcome the coulombic attraction of the hole. These results are promising for the design of dye molecules with such scaffolds, to achieve better efficiency and to eliminate one of the major issues with π-spacer units in DSSCs.

This work reports homoconjugated norbornylogous spacers to supress agglomeration of dye molecules with improved efficiency of dye sensitized solar cells.