Superficial siderosis of the central nervous system in a patient with asymptomatic sacral paraganglioma as source of chronic bleeding. / Siderosis superficial del sistema nervioso central en una paciente con paraganglioma sacro asintomático como fuente de sangrado crónico.

INTRODUCTION: Superficial siderosis of the central nervous system is an infrequent pathology secondary to chronic bleeding into the cerebrospinal fluid. Spinal tumors are infrequent cause of superficial siderosis being ependymoma the most common etiology. CASE REPORT: We report the case of a woman with sensorineural hearing loss and cerebellar ataxia, diagnosed of superficial siderosis on brain MRI. She had no previous history of axial back pain or radicular leg pain or bowel or bladder incontinence. On spine MRI an intradural lesion was found at the S1 level. No signs of intratumoral hemorrhage were observed on MRI gradient-echo images. At surgery, an intradural soft mass with signs of chronic bleeding was completely resected. Based on microscopic examination and immunohistochemistry of the specimen, a diagnosis of paraganglioma World Health Organization grade I was made. CONCLUSIONS: Since the only proven treatment able to prevent further deterioration from superficial siderosis is to stop chronic bleeding into subarachnoid space, is of paramount importance to establish an early diagnosis of the source of bleeding. Cases of unexplained superficial siderosis of central nervous system should include routine spinal MRI to rule out bleeding of spinal tumor even in asymptomatic patients. Due to severity of potential deterioration caused by superficial siderosis, any tumoral lesion observed on spinal MRI even without documented sings of bleeding should be considered for resection.

TITLE: Siderosis superficial del sistema nervioso central en una paciente con paraganglioma sacro asintomático como fuente de sangrado crónico.Introducción. La siderosis superficial del sistema nervioso central es una patología poco frecuente secundaria al sangrado crónico en el líquido cefalorraquídeo. Los tumores medulares son causa poco habitual de siderosis superficial, y el ependimoma es la etiología más común. Caso clínico. Mujer con pérdida auditiva neurosensorial y ataxia cerebelosa, diagnosticada de siderosis superficial en la resonancia magnética cerebral. No tenía antecedentes de dolor raquídeo axial, dolor radicular ni incontinencia esfinteriana. En la resonancia magnética de la columna se encontró una lesión intradural en S1. No se observaron signos de hemorragia intratumoral en las secuencias de resonancia magnética en eco de gradiente. En la cirugía, se apreció una masa blanda intradural con signos de sangrado crónico que se resecó. Basado en el examen microscópico e inmunohistoquímico de la muestra, se alcanzó el diagnóstico de paraganglioma de grado I de la Organización Mundial de la Salud. Conclusiones. Dado que el único tratamiento probado capaz de prevenir un mayor deterioro por la siderosis superficial es detener el sangrado crónico en el espacio subaracnoideo, es importante establecer un diagnóstico temprano de la fuente de sangrado. Los casos no justificados de siderosis superficial del sistema nervioso central deben incluir una resonancia magnética de la columna rutinaria para descartar el sangrado de un tumor medular, incluso en pacientes asintomáticos. Debido a la gravedad del deterioro potencial causado por la siderosis superficial, cualquier lesión tumoral observada en una resonancia magnética del raquis, incluso sin presentar signos de sangrado, debería ser objeto de indicación quirúrgica.

Eosinophils: Old Players in a New Game.

Eosinophils are terminal polymorphonuclear cells with a high number of cytoplasmic granules that originate in bone marrow. Some are exosomes, which contain multiple molecules, such as specific eosinophilic proteins, cytokines, chemokines, enzymes, and lipid mediators that contribute to the effector role of these cells. Moreover, exosomes present a large number of receptors that allow them to interact with multiple cell types. Eosinophils play an important role in defense against infestations and are a key element in asthma and allergic diseases. Eosinophils are recruited to the inflamed area in response to stimuli, modulating the immune response through the release to the extracellular medium of their granule-derived content. Various mechanisms of degranulation have been identified. Polymorphonuclear leukocytes contain multivesicular bodies that generate exosomes that are secreted into the extracellular environment. Eosinophilic exosomes participate in multiple processes and mechanisms. Eosinophils participate actively in asthma and are hallmarks of the disease. The cells migrate to the inflammatory focus and contribute to epithelial damage and airway remodeling. Given their relevance in this pathology, new therapeutic tools have been developed that target mainly eosinophils and their receptors. In this manuscript, we provide a global, updated vision of the biology of eosinophils and the role of eosinophils in respiratory diseases, particularly asthma. We also summarize asthma treatments linked to eosinophils and new therapeutic strategies based on biological products in which eosinophils and their receptors are the main targets.

Ultrasensitive mass sensing with a nanotube electromechanical resonator.

Shrinking mechanical resonators to submicrometer dimensions (approximately 100 nm) has tremendously improved capabilities in sensing applications. In this Letter, we go further in size reduction using a 1 nm diameter carbon nanotube as a mechanical resonator for mass sensing. The performances, which are tested by measuring the mass of evaporated chromium atoms, are exceptional. The mass responsivity is measured to be 11 Hz x yg(-1) and the mass resolution is 25 zg at room temperature (1 yg = 10(-24) g and 1 zg = 10(-21) g). By cooling the nanotube down to 5 K in a cryostat, the signal for the detection of mechanical vibrations is improved and corresponds to a resolution of 1.4 zg.

Imaging mechanical vibrations in suspended graphene sheets.

We carried out measurements on nanoelectromechanical systems based on multilayer graphene sheets suspended over trenches in silicon oxide. The motion of the suspended sheets was electrostatically driven at resonance using applied radio frequency voltages. The mechanical vibrations were detected using a novel form of scanning probe microscopy, which allowed identification and spatial imaging of the shape of the mechanical eigenmodes. In as many as half the resonators measured, we observed a new class of exotic nanoscale vibration eigenmodes not predicted by the elastic beam theory, where the amplitude of vibration is maximum at the free edges. By modeling the suspended sheets with the finite element method, these edge eigenmodes are shown to be the result of nonuniform stress with remarkably large magnitudes (up to 1.5 GPa). This nonuniform stress, which arises from the way graphene is prepared by pressing or rubbing bulk graphite against another surface, should be taken into account in future studies on electronic and mechanical properties of graphene.

Mechanical detection of carbon nanotube resonator vibrations.

Bending-mode vibrations of carbon nanotube resonators were mechanically detected in air at atmospheric pressure by means of a novel scanning force microscopy method. The fundamental and higher order bending eigenmodes were imaged at up to 3.1 GHz with subnanometer resolution in vibration amplitude. The resonance frequency and the eigenmode shape of multiwall nanotubes are consistent with the elastic beam theory for a doubly clamped beam. For single-wall nanotubes, however, resonance frequencies are significantly shifted, which is attributed to fabrication generating, for example, slack. The effect of slack is studied by pulling down the tube with the tip, which drastically reduces the resonance frequency.