Association of prooxidant-antioxidant disorders with the development of morphofunctional disorders in rats with subtotal cerebral ischemia

The aim of the study was to investigate morphofunctional disorders of neurons in the cerebral cortex and changes in the prooxidant-antioxidant state in rats after subtotal cerebral ischemia. Material and methods. The experiments were performed on 20 white outbred male rats. Surgical interventions were carried out under intravenous thiopental anesthesia (40–50 mg/kg). Subtotal cerebral ischemia was simulated by both common carotid arteries ligation. Animals were decapitated after 60 minutes of ischemia. Morphological and functional changes in the neurons of the parietal cortex and hippocampal CA1 field, and intensity of free radical oxidative processes (content of thiobarbituric acid reactive substances and thiol-disulfide system components) in brain homogenates were studied. Results and discussion. Brain ischemia has been followed by oxidative stress in brain tissue. The cellular metabolism has been disturbed under the oxidative stress that leads to a water-electrolyte imbalance, manifested by deformation of neuron bodies, wrinkling, and swelling. The changes in parietal cortex are to a greater extent expressed, as the neurons are more sensitive to oxygen deficiency

Determinación de la Envolvente de Falla por Corte mediante el Ajuste con el Método Estadístico de Error en Variables a través de la Relación entre las Tensiones Principales

El presente trabajo se fundamentó en el desarrollo de la representación paramétrica de la envolvente de falla a los círculos de Mohr en roca intacta, en función de las tensiones principales. En el método propuesto, las tensiones se ajustan utilizando el método estadístico EIV (error en las variables), el cual no hace distinciones artificiales entre las variables independientes y dependientes. Para complementar la transformación desde el plano de esfuerzos principales al plano de Mohr, se utilizó el método de Balmer mediante la aplicación del análisis algebraico computacional. Para ilustrar y verificar la aplicación de la metodología propuesta, se usó el bien documentado conjunto de datos coleccionados de trabajos previos de Pincus y Sheorey. Para probar las mejoras provistas por este método, se comparó la función objetivo calculada (minimizar la probabilidad de una decisión errónea) con la representación de la ecuación paramétrica obtenida, usando varios métodos de mínimos cuadrados. Se encontró que la metodología propuesta y la transformación del método de Balmer, tienen dos ventajas: i) simplifica el proceso de crear una envolvente de falla para aplicaciones prácticas, y ii) minimiza la posibilidad de un juicio erróneo durante las aplicaciones (como es indicar falla en un estado estable o viceversa)

Morphological disturbances of rat parietal cortex and hippocampus neurons in the dynamics steady subtotal ischemia of the brain

The purpose of the work is to analyze changes in the morphological characteristics of neurons of phylogenetical different parts of the cerebral cortex (parietal cortex and hippocampus) of rats at different periods in the dynamics of stepwise subtotal experimental cerebral ischemia. Methods. The experiments were performed on 42 males of outbred white rats. Step subtotal cerebral ischemia was performed as follows: first, one common carotid artery was ligated, simulating partial ischemia. Then, with an interval of 1 day (subgroup 1), 3 days (subgroup 2) or 7 days (subgroup 3), the second common carotid artery was ligated. Results. A microscopic study of the size, shape, degree of chromatophilia of the cytoplasm and the content of ribonucleoproteins in pyramidal neurons of phylogenetically different parts of the cerebral cortex have shown the dependence of the severity of brain damage on the interval between the cessation of blood flow in both carotid artery. Adaptation was better with a 7-day interval between dressings, while the ligation with an interval of 1 day, the degree of morphological changes was maximum indicating a lack of resources for the implementation of adaptation mechanisms

Fixed-Confidence Guarantees for Bayesian Best-Arm Identification

We investigate and provide new insights on the sampling rule called Top-Two Thompson Sampling (TTTS). In particular, we justify its use for fixed-confidence best-arm identification. We further propose a variant of TTTS called Top-Two Transportation Cost (T3C), which disposes of the computational burden of TTTS. As our main contributio

Response of parylene-coated NaI(Tl) scintillators at low temperature

Despite that it is widely used as a scintillator at room temperature, the hygroscopicity of NaI complicates its handling and limits its application for many purposes, for example as a cryogenic detector. To overcome this problem we study coating materials that can act as humidity barriers, in particular parylene, a polymer that can be deposited in very radiopure, thin and conformal layers. In this work, several NaI(Tl) samples coated with 2-5 µm parylene-C were tested at low temperature. Luminescence spectra under X-ray excitation are presented at several temperatures as well as the light output vs temperature at 1.5-300 K. Several thermoluminescence peaks were observed at around 60, 95 and 150 K during warm up to room temperature The mechanical resistance of the coating under thermal cycles was also investigated, and we observed a degradation of the optical appearance and the light output after cooling down to about 100 mK, which compromises the reusability of the samples

Fixed-confidence guarantees for Bayesian best-arm identification

We investigate and provide new insights on the sampling rule called Top-Two Thompson Sampling (TTTS). In particular, we justify its use for fixed-confidence best-arm identification. We further propose a variant of TTTS called Top-Two Transportation Cost (T3C), which disposes of the computational burden of TTTS. As our main contribu

Sodium oxybate in narcolepsy with cataplexy: Zurich sleep center experience

Sodium oxybate (SO; Xyrem®) has been approved in most countries for treatment of narcolepsy and cataplexy. In this study, we present a single-center experience of a series of 18 patients with narcolepsy with cataplexy (18/18 DQB1*0602 positive, 17/17 with low/absent cerebrospinal fluid hypocretin) in whom SO was prescribed. After 26 ± 13 months, 13/18 patients were still on SO at a mean dosage of 6.1 ± 1.2 g (in 8 of them in combination with stimulants). The following significant effects were observed: improved subjective sleepiness (12/13), cataplexy (13/13; median number of attacks from 20 to 1/month), hallucinations (8/10) and sleep paralysis (8/8); increase in mean sleep latency on the Maintenance of Wakefulness Test (from 5.5 to 17.4 min) and sleep/rest efficiency on actigraphy (from 61 to 76%); decrease in Epworth Sleepiness Scale score (from 18 to 14), sleep onset REM periods on the Multiple Sleep Latency Test (from 3.6 to 2.4) and errors in the Steer-Clear Test (from 11 to 2%). Five patients discontinued SO because of insufficient compliance (n = 2), lack of efficiency (n = 1) and side effects (n = 1). These data confirm and expand previous reports on the good effects and tolerability of SO as a treatment for narcolepsy with cataplexy