The effect of lesionectomy and the perilesional GABAergic neuronal changes in alumina cream-induced focal motor epilepsy in cats

Abstract

The effect of lesionectomy depends on the reversibility of the epileptogenic changes in the perilesional cortex. We studied how the perilesional GABAergic neuronal changes are related to the effect of lesionectomy in the alumina cream-induced focal epilepsy model in cats. Sequential changes of GABAergic neurons and spike activities were measured after the micro-injections of alumina cream (AC). Alumina granulomas were excised 15 days and 40 days after the injections. At day 20 following the AC injectionl GABAergic neurons were decreased 25 to 40% compared with those in the contralateral intact cortex. At day 401 a significant increase of spike activities occurred. GABA positive cells were decreased more than 50% compared with those in the contralateral cortex. At day 801 significant cell loss inperilesional cortex was demonstrated. The effect of lesionectomy was greater in the early excised group than in the late excised group. Decrease of GABAergic neuron was more severe in the late excised group compared to the early excised group. Our results indicate that more than 50% reduction of perilesional GABA neurons may be a critical point in epileptogenesis in this model. Lesionectomy alone prior to a 50% reduction in perilesional GABAergic neurons may be sufficient for seizure control. With these data it is still unclear whether these findings contribute to the choice between lesionectomy alone and lesionectomy with resection of the perilesional cortex. Further study is needed to understand the difference between the AC epilepsy model and human chronic epilepsy. [Neural Res 1998; 20: 253-258]]     

Effect of alumina particle morphology used for air abrasion on loss of enamel and luting composite resin

ObjectiveTo evaluate the volume loss after air abrasion with alumina particles with different morphology on bovine enamel and luting composite resin.MethodsAir abrasion was performed on 12 unscathed bovine teeth and 72 luting composite resin discs with 85 μm round-shaped and 50 μm sharp-edged alumina particles applied for 20 s, 40 s and 60 s (n = 12). Air abrasion was standardized by uniform areas of 2 mm diameter, a pressure of 0.25 MPa and a distance of 3 mm. The volume loss was determined by using a laboratory scanner.ResultsAir abrasion with round-shaped alumina particles was mostly not measurable with the laboratory scanner, while sharp-edged alumina air abrasion resulted in significant loss of enamel. The median of volume loss by sharp-edged alumina particles ranged from 0.78 mm³ (20 s) to 2.52 mm³ (60 s). In contrast to round-shaped alumina the removal caused by sharp-edged alumina increased significantly with increasing application times (p ≤ 0.05). For air abrasion on luting composite resin the median of the removed volume ranged from 2.25 mm³ (20 s) to 6.18 mm³ (60 s), while round-shaped alumina showed a range from 0.45 mm³ (20 s) to 1.40mm³ (60 s). The round-shaped alumina produced a statistically significant lower volume loss than sharp-edged alumina for all three air abrasion times.SignificanceThe 85 μm round-shaped alumina particles removed less composite resin than 50 μm sharp-edged alumina particles but barely any enamel, making it an option for removing composite resin residues from enamel.     

Chipping fracture resistance of dental CAD/CAM restorative materials: Part 2. Phenomenological model and the effect of indenter type

The edge chipping resistances of six CAD/CAM dental restoration materials are analyzed and correlated to other mechanical properties. A new quadratic relationship that is based on a phenomenological model is presented.     

Intracellular records from chronic alumina epileptogenic foci in the monkey

Neuronal records from the primate alumina focus revealed synaptic potentials with bursts of action potentials occurring on depolarizing potentials. These depolarizing potentials were not synchronous with electrocorticographic epileptic patterns. The configuration of the membrane potential changes was consistent with a dendritic generator for epileptic bursts. It is proposed that the genesis of these depolarizing potentials is postsynaptic.     

厚度对CAD／CAM氧化铝颜色的影响

目的：研究不同底层瓷及饰瓷厚度对氧化铝全瓷修复体色度的影响。方法：制作0.5mm、0.7mm、0.9mm、1.1mm厚度的氧化铝底层瓷试件,打磨抛光,采用ShadeEye NCC比色仪测量色彩参数;在不同厚度底层瓷表面分别堆塑厚度1.1mm、0.9mm、0.7mm、0.5mm饰瓷,控制总厚度1.6mm,比色仪测量所有试件的色彩参数。制作0.5mm厚度氧化铝试件,分别构筑0.5mm、0.8mm、1.1mm和1.4mm厚度饰瓷层,比色仪测量所有试件的色彩参数。结果：随着饰瓷层厚度增加,试件之间颜色度差异明显;随底层材料厚度增加,L＊、b＊值和C＊ab值增大,试件间色度差明显。结论：通过对饰瓷和底层瓷厚度的调节,可以改变氧化铝全瓷修复体的颜色。     

采用CAD/CAM和玻璃渗透技术制作高强度全瓷冠的研究

目的　探索用 CAD/CAM切削加工和玻璃渗透技术相结合制作高强度全瓷基底冠的方法。方法　采用自行研制的部分烧结氧化铝块 ,经 Cerec CAD/CAM系统加工制作氧化铝基底冠 ,并经玻璃渗透完成高强度底冠的制作 ,再用 Vita alpha饰瓷制作完成全瓷冠。结果　与常规的 In- Ceram技术相比 ,本文方法无需复制耐火代型和 10小时的氧化铝基底冠的烧结过程 ,且由于预成的氧化铝块颗粒分布均匀 ,具有更强的毛细管作用 ,全冠的渗透时间由原来的 4小时缩短为 40分钟。结论　采用工业预成的瓷块 ,经牙科 CAD/CAM加工成一个形状复杂的修复体是未来全瓷修复的发展方向