Levetiracetam prophylaxis ameliorates seizure epileptogenesis after fluid percussion injury.

To determine whether post-traumatic seizure severity would be affected by the interval between seizures and head injury, we measured seizures after various times with or without fluid percussion brain injury (2atm fluid percussion injury; FPI). To determine efficacy of anti-seizure medication, we also determined if levetiracetam (LEV) would alter the relationship between injury and subsequent seizures. Early post-traumatic seizures were induced by Kainic acid (KA) at one week after 2atm fluid percussion injury (FPI) in one group (FPI-ES). Seizures were induced at two weeks after FPI by KA in another group (FPI-LS). In addition, one group had induced seizures by KA without FPI, (sham-ES). Finally one group of animals received the antiepileptic agent (levetiracetam) infusion for one week after FPI and then had seizures induced by KA (FPI-LEV-ES). We measured seizure onset time, ictal duration and severity of seizures using a modified Racine's scale. Histopathological changes in the hippocampus CA1 region were also analyzed. Severity of seizures were increased in the FPI-ES group compared with sham-ES animals. Severity was also enhanced in early post-injury seizures induced by KA (FPI-ES vs. FPI-LS); this exacerbation of seizure severity could be ameliorated by levetiracetam infusion (FPI-ES vs. FPI-LEV-ES). Neuronal degeneration in CA1 was more severe in the FPI-ES group and this degeneration was also diminished by LEV. We conclude that early post injury seizures exacerbate susceptibility and severity of post traumatic seizures and increase neuronal degeneration in the CA1 layer of hippocampus. These changes are partially reversed by LEV infusion after FPI.

[Effects of nitrogen application on canopy vertical structure, grain-leaf ratio and economic benefit of winter wheat under drip irrigation.] / æ–½æ°®é‡å¯¹æ»´çŒå†¬å°éº¦å† å±‚åž‚ç›´ç»“æž„ç‰¹å¾ã€ç²’å¶æ¯”åŠç»æµŽæ•ˆç›Šçš„å½±å“.

To optimize the fertilization rate of winter wheat under drip irrigation in Xinjiang region, a field investigation was carried out to assess effects of nitrogen (N) applications on canopy vertical structure, grain-leaf ratio, yield and economic benefit of winter wheat. Four rates of nitrogen application, 0 kg·hm-2(N0), 104 kg·hm-2(N1), 173 kg·hm-2(N2) and 242 kg·hm-2(N3) were set in a randomized block experimental design. Meantime, leaf and stem morphological characters, canopy temperature and humidity in flowering stage, grain-leaf area ratio, yield and yield components, economic benefits of winter wheat were observed under different treatments. The results showed that the leaf length and width at different positions of wheat under the nitrogen fertilization treatments were significantly higher than that without nitrogen fertilization (P<0.05), and plant height ranged from 65.57 to 81.58 cm. With an increasing rate of nitrogen fertilization, both leafarea index and stem diameter presented a trend of first increasing and then decreasing, and reached the maximum under N2 treatment, which was 5.48 and 0.49 cm, respectively. Diurnal variation of canopy temperature and humidity were "convex" and "concave" shape, followed an order of N0>N1>N2>N3 in temperature, but reversely in canopy humidity. The duration of high temperature higher than 35 ℃ were shorten 1 hour to 3.5 hours as the nitrogen application level increased, and there was significant difference between N1 and N3 on grain-leaf ratio. Yield and economic be-nefit decreased initially and then increased with increasing nitrogen application. Yield and economic benefit of treatment N2 were 32.8% and 77.7% higher than those of treatment N0, 12.6% and 5.4% higher than those of treatment N1, and 5.2% and 4.2% higher than those of treatment N3, respectively. These results indicated that nitrogen application at about 173 kg·hm-2 could be recommended as the optimum rate for winter wheat, which had good leaf and plant morphology, appropriate canopy temperature and humidity, high yield and economic efficiency in the experiment area.