Results 1 - 10 of 15938
Results 1 - 10 of 15938. Search took: 0.041 seconds
|Sort by: date | relevance|
[en] This paper presents novel design, fabrication, packaging and the first in vitro neural activity recordings of SU-8-based microneedles. The polymer SU-8 was chosen because it provides excellent features for the fabrication of flexible and thin probes. A microprobe was designed in order to allow a clean insertion and to minimize the damage caused to neural tissue during in vitro applications. In addition, a tetrode is patterned at the tip of the needle to obtain fine-scale measurements of small neuronal populations within a radius of 100 µm. Impedance characterization of the electrodes has been carried out to demonstrate their viability for neural recording. Finally, probes are inserted into 400 µm thick hippocampal slices, and simultaneous action potentials with peak-to-peak amplitudes of 200–250 µV are detected.
[en] Targeted drug delivery to the brain parenchyma, i.e., in brain tumor patients, by means of magnetically supported carrier delivery through the tight vascular endothelium of the blood-brain barrier is of critical biomedical importance. We were interested in delineating the first steps in successful brain drug delivery, which focuses on the interactions between magnetically guided yet freely blood circulating nanoparticles and the blood-brain barrier. We employed an in vivo model to quantitatively determine changes in cerebrovascular flow rate and volume during magnetically guided exposure of circulating nanoparticles.
[en] Epithelioid hemangioendothelioma (EHE) is a rare vascular soft-tissue tumour of intermediate malignancy. Neurofibromatosis type I (NF-1) is a genetic syndrome associated with soft tissue sarcoma and higher risk of developing neoplasia. Lateral meningoceles are uncommon entities, being mostly associated with NF-1. We report a case of a 31-year-old woman, with NF-1 and past history of right thalamic/peduncular astrocytoma WHO grade II, admitted to the Neurosurgery Department in December 2003 due to severe low back pain, irradiating to the left leg without a radicular pattern. Thoraco-lumbar magnetic resonance imaging (MRI) showed a large left posterior paravertebral expansive lesion, bilateral and multiple thoraco-lumbar lateral meningoceles and dural ectasias with scalloping of the vertebral bodies. Biopsy of the paravertebral mass lesion disclosed EHE. We present this case because of the novel association between NF-1 and EHE, and the unusual aggressiveness of the neoplasia. Additionally, we highlight the co-existence of bilateral and multiple lateral meningoceles. (orig.)
[en] Collective cell motility is an important aspect of several developmental and pathophysiological processes. Despite its importance, the mechanisms that allow cells to be both motile and adhere to one another are poorly understood. In this study we establish statistical properties of the random streaming behavior of endothelial monolayer cultures. To understand the reported empirical findings, we expand the widely used cellular Potts model to include active cell motility. For spontaneous directed motility we assume a positive feedback between cell displacements and cell polarity. The resulting model is studied with computer simulations and is shown to exhibit behavior compatible with experimental findings. In particular, in monolayer cultures both the speed and persistence of cell motion decreases, transient cell chains move together as groups and velocity correlations extend over several cell diameters. As active cell motility is ubiquitous both in vitro and in vivo, our model is expected to be a generally applicable representation of cellular behavior
[en] Highlights: • We analyze spike trains induced by EA before and after inhibiting SP in PC6 area. • Inhibiting SP leads to an increase of spiking rate of median nerve. • SP may modulate membrane potential to affect the spiking rate. • SP has an influence on long-range correlation of spike train evoked by EA. • SP play an important role in EA-induced neural spiking and encoding. - Abstract: Substance P (SP) participates in the neural signal transmission evoked by electro-acupuncture (EA). This paper investigates the impact of SP on the correlation of spike train in the median nerve evoked by EA at 'Neiguan' acupoint (PC6). It shows that the spiking rate and interspike interval (ISI) distribution change obviously after inhibiting SP. This variation of spiking activity indicates that SP affects the temporal structure of spike train through modulating the action potential on median nerve filaments. Furtherly, the correlation coefficient and scaling exponent are considered to measure the correlation of spike train. Scaled Windowed Variance (SWV) method is applied to calculate scaling exponent which quantifies the long-range correlation of the neural electrical signals. It is found that the correlation coefficients of ISI increase after inhibiting SP released. In addition, the scaling exponents of neuronal spike train have significant differences between before and after inhibiting SP. These findings demonstrate that SP has an influence on the long-range correlation of spike train. Our results indicate that SP may play an important role in EA-induced neural spiking and encoding.
[en] Early models of the oculomotor plant only considered the eye globes and the muscles that move them. Recently, connective tissue structures have been found enveloping the extraocular muscles (EOMs) and firmly anchored to the orbital wall. These structures act as pulleys; they determine the functional origin of the EOMs and, in consequence, their effective pulling direction. A three dimensional model of the oculomotor plant, including pulleys, has been developed and simulations in Simulink were performed during saccadic eye movements. Listing's law was implemented based on the supposition that there exists an eye orientation related signal. The inclusion of the pulleys in the model makes this assumption plausible and simplifies the problem of the plant noncommutativity
[en] To assess the prognostic potential for N-cadherin in oral squamous cell carcinoma and oral epithelial dysplasia. Study Design: A cross-sectional study, analytical study. Place and Duration of Study: Maharishi Markandeshwar College of Dental Science Research (MMCDSR), Ambala, India, from 2011 to 2014. Methodology: Immunohistochemistry was used to observe the N-cadherin expression in 100 cases having epithelium with normal oral mucosa, oral epithelial dysplastic lesions and oral squamous cell carcinoma (OSCC). For statistical significance, SPSS 13.0 was used to calculate the data by Mann-Whitney and Kruskal-Wallis tests. Results: In OSCC, N-cadherin expression was more evident than in oral epithelial dysplasia followed by the normal oral epithelium that did not show any dysplastic changes (p=0.001). Conversely, N-cadherin expression was not significant among the histological grade of OSCC. Conclusion: N-cadherin can be used as a potential biomarker for early diagnosis of OSCC. However, the N-cadherin expression did not show any correlation with the histological grade of OSCC. (author)
[en] Aim: When using perfusion-weighted magnetic resonance imaging (MRI) in lesions with blood-brain barrier (BBB) disruption two methods are normally applied to eliminate the influence of contrast material uptake on T2* dynamics: injection of contrast agent before starting perfusion imaging (pre-injection) and simultaneous acquisition of T1- and T2*-dynamics using a dual echo (DE)-FLASH sequence. The purpose of this study was to examine both methods with regard to their reliability. Material and methods: We performed four perfusion measurements in a patient with a primary cerebral lymphoma located in the corpus callosum: two measurements with a DE-FLASH sequence and two measurements with a gradient-echo echo-planar-imaging (GE-EPI) sequence, respectively. In both cases there was one measurement with and one without pre-injection of contrast material. Results: Pre-injection of contrast material reduced the influence of T1 and allowed us to monitor the transient signal drop when using the GE-EPI sequence. Analysis of the time-course of DE-FLASH, however, showed that there was still a T1 decrease even after pre-injection. After the first pass the T2*-dynamics showed a distinct long-term T2*-decrease. Discussion: Neither pre-injection nor DE-FLASH allow us to eliminate the effects of contrast agent uptake completely. Both methods, however, increase the reliability of perfusion MRI. Their efficacy depends on the extent of the BBB disruption. (orig.)
[de]Zielsetzung: Bei der Perfusions-Magnetresonanztomographie (MRT) von Laesionen mit Stoerung der Blut-Hirn-Schranke (BHS) werden derzeit zwei Verfahren angewendet, um stoerende Effekte der Kontrastmittelanreicherung auszuschliessen: Die Injektion von Kontrastmittel vor der eigentlichen Perfusionsmessung (Prae-Injektion) sowie die simultane Aufnahme einer T1- und T2*-Dynamik mit einer Doppelecho(DE)-FLASH-Sequenz. Ziel war es, beide Verfahren hinsichtlich ihrer Zuverlaessigkeit zu vergleichen. Material und Methode: Bei einem Patienten mit einem primaeren Hirnlymphom im Corpus callosum wurden vier Perfusionsmessungen durchgefuehrt: Je zwei Messungen mit einer DE-FLASH- und einer Gradientenecho Echo-Planar-Imaging (GE-EPI)-Sequenz, jeweils mit und ohne Prae-Injektion von Kontrastmittel. Ergebnisse: Durch Prae-Injektion von Kontrastmittel konnte der T1-Effekt so stark reduziert werden, dass der transiente Signalabfall in der GE-EPI-Sequenz sichtbar wurde. Die DE-FLASH-Sequenz zeigte jedoch, dass auch mit Prae-Injektion die T1-Relaxationszeit waehrend des Bolusdurchgangs abnimmt. In der korrigierten T2*-Dynamik war nach Kontrastmittelpassage eine deutliche T2*-Verringerung zu erkennen. Diskussion: Weder die Prae-Injektion von Kontrastmittel noch die DE-FLASH-Sequenz eliminieren die Effekte der Kontrastmittelanreicherung. Dennoch wird die Zuverlaessigkeit der Messung erhoeht, wobei die Effizienz der beiden Verfahren von der Staerke der BHS-Stoerung abhaengt. (orig.)
[en] Cemento-osseous dysplasias are a group of disorders known to originate from periodontal ligament tissue and involve, essentially, the same pathological process. They are usually classified into three main groups: periapical, florid, and focal cemental dysplasias depending on their extent and radiographic appearances. Radiographically, florid cementoosseous dysplasia (FCOD) appears as dense, lobulated masses, often symmetrically located in various regions of the jaws. The best management for the asymptomatic FCOD patient consists of regular recall examinations with prophylaxis. The management of the symptomatic patient is more difficult. A case of FCOD occurring in a 52-year-old edentulous Korean female is reported which is rare with regard to race and sex.
[en] Acardiac twinning is a severe and rare complication of monochorionic placentation. The acardiac twin does not survive while mortality of the normal twin is about 50-70 % as the normal twin has to provide circulation not only for itself but also for acardiac twin. Proper timing of the delivery is of prime importance to the survival of the normal fetus for which emphasis is placed on close sonographic monitoring for early antenatal diagnosis. This series describes three such cases, which are now termed Twin Reversed Arterial Perfusion (TRAP) sequence. (author)