Significance of spikes recorded on intraoperative electrocorticography in patients with brain tumor and epilepsy

PURPOSE: Patients with medically intractable epilepsy due to brain tumors may undergo resective surgery for treatment of both the tumor and the epilepsy. In this instance, the extent of surgical resection is sometimes guided by spikes recorded on intraoperative electrocorticography (ECoG). Whether spikes recorded by electrocorticography imply active epileptogenicity has not been addressed adequately. METHODS: We performed preresection and postresection electrocorticography on 36 patients with brain tumor and seizures. There were 31 low-grade gliomas, 4 high grade gliomas, and 1 dysembryonic neuroepithelial tumor. Patients had resection of the tumor to normal tissue margins only. No additional surgery was performed, based on electrocorticography findings. Patients were divided into 2 groups: Group I (no seizures or rare seizures after resection) and Group II (recurrent seizures). Recorded spikes were analyzed for spike distribution and spike discharge rate. RESULTS: On preresection ECoG, 85% of patients in Group I and 88% of patients in Group II had spikes. In Group I, 70% of patients had spikes over the tumor bed, and 63% of patients had spikes in the surrounding tissue. In Group II, 55% of patients had spikes over the tumor bed and 89% of patients had spikes in the surrounding tissue. Spike distribution and discharge rate did not correlate with outcome. On postresection ECoG, 60% of patients in Group I and 67% of patients in Group II had residual spikes. In Group I, 46% of patients had spikes along the margin of resection and 26% of patients had extramarginal spikes. In Group II, 50% had spikes along the margin of resection and 67% of patients had extramarginal spikes. CONCLUSIONS: The difference in spike distribution in the extramarginal area between the 2 groups was not statistically significant, but showed a trend toward a relationship between postresection spikes and seizure recurrence.     

Predicting the outcome in elderly patients of hospital admission for acute care in Paris, France: construction and initial validation of a simplex index

An update on renal genetic mechanisms of spontaneous hypertension in rats and in human essential hypertension is presented. The findings are discussed, highlighting the search of a possible link between the discovered genetic abnormality and the renal function changes that may determine the disease. The analogies (and/or differences) between the numerous positive findings obtained in animal models and the relatively scarce ones obtained in humans are discussed.     

Vascular expression of E-selectin is increased in estrogen-receptor-negative breast cancer: a role for tumor-cell-secreted interleukin-1 alpha

Angiogenesis plays an important role in breast cancer growth and metastasis. Multiple adhesion molecules have been shown to perform critical functions in the process of angiogenesis. In this study, we analyzed 15 benign and 22 malignant estrogen-receptor-negative and estrogen-receptor-positive breast specimens for the presence of the endothelial cell adhesion molecules E-selectin and P-selectin. We found that E-selectin's expression was increased in the malignant breast tumors compared with their benign counterparts (23.86% of blood vessels versus 2.47%; P = 0.0005). Furthermore, E-selectin staining was found to be significantly increased in the estrogen-receptor-negative carcinomas compared with the estrogen-receptor-positive ones (P = 0.005). In vitro findings strongly correlated with the in vivo findings and showed a higher degree of E-selectin induction in endothelial cells exposed to conditioned media from estrogen-receptor-negative breast cancer cell lines than from estrogen-receptor-positive ones. The degree of E-selectin induction correlated with the amount of interleukin-1 alpha in the tumor-conditioned media. Neutralizing antibodies to interleukin-1 alpha significantly inhibited the E-selectin expression in endothelial cells exposed to tumor-conditioned media. The results indicate that the endothelial E-selectin expression during angiogenesis is related to breast carcinoma progression in vivo and that this component of angiogenesis may be due directly to tumor-cell-secreted interleukin-1 alpha.     

On Stress Intensity Factors of Multiple Cracks at Small Distances in 2-D Problems

In the present work a method is proposed to predict stress intensity factors (SIFs) of strongly interacting cracks at spacings that are substantially smaller than crack lengths. The method is intended for applications where cracks are observed in stack-like/staggered arrangements as in damage patterns of some natural materials with dense lamellar microstructures. The new calculation procedure is inspired by the analytical method of Kachanov (1987) that due to its simplicity has shown to be a powerful tool for analysis of crack interactions. Although in 3-D the accuracy of Kachanov’s method remains good at quite close spacings, in 2-D problems it, however, quickly drops as the distance between cracks decreases, underestimating the effect of crack interactions, especially in ordered staggered arrangements. In this work we introduce new modeling assumptions that are suited for problems where stress fields have high gradients – a typical situation in the case of closely spaced parallel cracks. The accuracy of the method is examined on the example of two stacked cracks. The use of SIFs for estimation of material elastic compliance is also discussed.     

Molecular dynamics study on local structure of amorphous and liquid Al2O3

Microscopic features of liquid and amorphous alumina (Al₂O₃) were simulated by molecular dynamics calculations. The simulations were performed in an orthorhombic cell with 3000 particles using the Born-Mayer potential at temperatures of 0, 2500, 2700, and 3000 K under constant pressure. It was found that a large cluster of pores contained several thousand spherical pores, which were formed with radii larger than 0.73 Å. The observed variations of Al₂O₃ structures with atomic arrangements of AlO_x (x=3, 4, 5, and 6) are discussed.     

Modeling of a locking mechanism between two rough surfaces under cyclic loading

The work is motivated by experimental studies on energy dissipation due to micro-slip in mechanical joints. It has been observed that the loss of energy undergoes certain evolution under cyclic shear loading. It manifests itself in the form of the gradual decrease approaching a steady state as cycling progresses. This behavior has a repeatable character if contact is re-established and subjected to cycling again. In the present work, a simple multiple-asperity model is developed that suggests a physical hypothesis that when two rough surfaces are brought in contact and subjected to shear loads a certain locking mechanism comes into play at the interface. Such locking occurs due to the tendency of the interface to adapt its contact microstructure to the loading conditions. The adaptation mechanism is described in the present work through the contact inclination angles. The developed model is simple in application and it relates micro-characteristics of the contact to macro-behavior of the system exhibiting itself in energy dissipation.     

Synthesis of hyperbranched conjugated polymers based on 3-hexylthiophene,triphenylamine and benzo [c] [1,2,5] thiadiazole moieties: convenient synthesis through suzuki polymerization and impact of structures on optical properties

Novel 3-hexylthiophene-based hyperbranched conjugated polymers containing triphenylamine and benzo [c] [1, 2, 5] thiadiazole moieties were synthesized by Suzuki coupling polymerization of tris (4-bromophenyl) amine, 2,2′-(3-hexylthiophene-2,5-diyl) bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and 4,7-dibromobenzo [c] [1, 2, 5] thiadiazole. Organic solvent-soluble polymers with number-average molecular weights of 24,000 and 42,000 g/mol were obtained in 54–57 % yields. Their structures, molecular weights and thermal properties were characterized via proton nuclear magnetic resonance (¹H NMR) and Fourier transform infrared (FT-IR) spectroscopies, gel permeation chromatography (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and wide-angle powder X-ray diffraction (XRD) measurements. Optical investigation by UV–vis and fluorescence spectroscopies revealed that the incorporation of the benzo [c] [1, 2, 5] thiadiazole moiety in the hyperbranched polymer structure resulted in a red-shift of the maximum absorption wavelength and an increase in the solution-photoluminescence quantum yield, indicating an extension of the conjugation length. The UV–vis, DSC and XRD results demonstrated that the aggregation of conjugated polymer chains could effectively be reduced by the hyperbranched structures and that conjugation length extension via the introduction of benzo [c] [1, 2, 5] thiadiazole units led to the coexistence of both crystalline and amorphous phases in the solid state and in solution upon addition of a non-solvent.     

Different Directions of Switching of Chromium Oxide Thin Films

We have investigated the switching behavior of as-deposited CrO _x and post-annealed CrO _y films by use of a variety of electrodes (top electrode Ag, Ti; bottom electrode Pt, fluorine tin oxide (FTO)). Resistance switching is highly dependent on electrode material and post-annealing treatment. Among Pt devices, I–V hysteresis was observed for the Ag/CrO _x /Pt device only; no resistance switching was observed for Ag/CrO _y /Pt, Ti/CrO _x /Pt, and Ti/CrO _y /Pt devices. Among FTO devices, I–V hysteresis was observed for the Ag/CrO _x /FTO device whereas I–V hysteresis with the opposite switching direction was observed for Ag/CrO _y /FTO, Ti/CrO _x /FTO, and Ti/CrO _y /FTO devices. The direction of switching depends not only on electrode material but also on post-annealing treatment, which affects the density of grain boundaries. Thus, the density of grain boundaries determines the type of charge carrier involved in the switching process. For as-deposited CrO _x films with a high density of grain boundaries Ag filament paths mediated by electrochemical redox reaction were observed, irrespective of bottom electrode material (Pt or FTO). Post-annealed CrO _y films with a low density of grain boundaries suppressed electrochemical redox reaction in the Ag/CrO _y /Pt device but promoted short-range movement of O^2? ions through the bottom interface, resulting in resistance switching in the Ag/CrO _y /FTO device. Electrochemical redox reaction-controlled resistance switching occurred solely in oxides with a high density of grain boundaries or dislocations.