Cortical and hippocampal volume deficits in temporal lobe epilepsy

PURPOSE: To use quantitative magnetic resonance imaging (MRI) methods to examine the extent of volume abnormalities in the hippocampus and in extrahippocampal brain regions in localization-related epilepsy of temporal lobe origin (TLE). METHODS: Hippocampal, temporal lobe, and extratemporal lobe volumes were examined with 3-mm spin-echo coronal MRI scans in patients with unilateral TLE who were candidates for temporal lobe resection. Measures were adjusted for normal variation due to intracranial volume and age based on 72 healthy male controls. Group differences between 14 male TLE [7 left TLE (LTLE), 7 right TLE (RTLE)] patients and a subset of 49 age range-matched controls were examined with analysis of variance (ANOVA). RESULTS: As compared with controls, patients with TLE had smaller temporal lobe and frontoparietal region gray matter volumes, bilaterally, smaller temporal lobe white matter volumes bilaterally, and larger ventricular volumes. In contrast to these bilateral tissue volume deficits, hippocampal volume deficits in TLE were ipsilateral to the epileptogenic temporal lobe. CONCLUSIONS: Extrahippocampal volume abnormalities were bilateral and occurred in both temporal and extra-temporal cortical regions in TLE, whereas hippocampal deficits were related to the side of the epileptogenic focus. These data suggest that brain abnormalities in TLE are not limited to the epileptogenic region.     

Metabolic Fate of the Environmental Mutagen 3-Nitrofluoranthene in the Rat

3-Nitrofluoranthene, a potent environmental mutagen, was administered to rats intraperitoneally at 10 mg/kg, labelled with ¹⁴C. Urine contained 15 to 20% of the dose, eliminated mainly within the first 24 hours after dosing. Over 95% of the radioactivity in unhydrolysed urine chromatographed with the solvent front in a reverse-phase HPLC system, indicating extensive conjugation. After hydrolysis with β-glucuronidase (containing sulfatase) and concentration on C18-Sep-Pak, urine was fractionated by HPLC for further characterization. NMR analysis of the metabolite fractions indicated that positions 4, 8 and 9 were major sites of oxidation. Both acetamide and amine derivatives were formed. The finding of multiple oxidation and incomplete acetylation is in contrast to the fate of 1-nitropyrene, where 1-acetamidopyren-6-ol, itself a potent mutagen, represents the major metabolic product. This difference in metabolism pathways may have implications for the genotoxicity of 3-nitrofluoranthene.     

Double aperture double-gate vertical high-electron-mobility transistor

In this paper, we propose a double aperture double-gate AlGaN/GaN vertical high-electron-mobility transistor (HEMT) to improve the device characteristics, such as the current and the ON resistance (\(\hbox {\textit{R}}_{\mathrm{ON}}\)). The proposed vertical HEMT results are compared to the conventional single aperture single-gate vertical HEMT of equal dimensions, and increased drain current and lower \(\hbox {\textit{R}}_{\mathrm{ON}}\) are shown. A comprehensive simulation study has also been carried out for the proposed device, to analyse the impact of thickness and doping concentration of aperture, drift region, and current blocking layer. In addition, the effect of different materials in current blocking layer on device characteristics is also studied. The obtained results and their effect on device characteristics have been thoroughly analysed and explained accordingly.     

Dual material gate junctionless tunnel field effect transistor

This paper proposes a junctionless tunnel field effect transistor (JLTFET) with dual material gate (DMG) structure and the performance was studied on the basis of energy band profile modulation. The two-dimensional simulation was carried out to show the effect of conduction band minima on the abruptness of transition between the ON and OFF states, which results in low subthreshold slope (SS). Appropriate selection of work function for source and drain side gate metal of a double metal gate JLTFET can also significantly reduce the subthreshold slope (SS), OFF state leakage and hence gives improved I _ON/I _OFF.     

Spatial and temporal scaling of nitrous oxide emissions from the field to the regional scale in Scotland

Nitrous oxide (N₂O) is a powerful greenhouse gas. As the UK government is committed to reducing greenhouse gas emissions, it is important to know not only how much of these gases are released but also where and when. Targeted measurements of emissions in relation to crop growth cycles, soil wetness and fertiliser applications were used to derive annual emission rates for specific combinations of soil type, land management and fertiliser practices. These annual emission rates were then spatially scaled to derive regional figures through the development of a Geographic Information System (GIS) based model framework. Digital soil and land use maps at a scale of 1:25000 for two test areas of approximately 200000 ha each (Lothians and the Ayrshire Basin) were overlain with a climate map within the GIS, deriving unique combinations of soil wetness and land use. The calculated annual emission rates (kg N ha^–1 yr^–1) were then applied to these and multiplied by the total area of each soil/land use type to derive annual emission losses for each area. The annual emission of nitrous oxide from the Lothians was determined as approximately 381000 kg N yr^–1, while the emissions from the Ayrshire Basin were predicted to be 794000 kg N yr^–1. This indicates the increased emissions associated with both the wetter soils of Ayrshire and the greater extent of grazed pasture systems in this area. Due to the detailed scale of the input data, localised areas with large emissions were identified. Abatement strategies would be concentrated on areas of high emissions that include a change to crops with lower emission potential, reducing fertiliser and manure inputs, reducing grazing intensity and improving soil drainage.Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1024422604493     

Distribution and Accumulation of the Alkaloid Peramine in Neotyphodium lolii-Infected Perennial Ryegrass

Through the production of alkaloids and mycotoxins, the endophytic fungus of perennial ryegrass, Neotyphodium lolii, confers resistance to the host grass against several insect pasture pests and causes health problems in livestock. The effects of plant component, plant reproductive development, and plant management (trimming) on the concentration and accumulation of peramine, the alkaloid thought to be most important for conferring resistance against Argentine stem weevil, were investigated. Clones of eight different naturally occurring perennial ryegrass-N. lolii associations were used in the experiment, which was conducted during spring–summer, which corresponded with the height of plant reproductive activity. Clones were either trimmed regularly to maintain them in a vegetative state (V clones) or not trimmed, allowing them to become fully reproductive (R clones). V and R clones of each grass/endophyte association were destructively harvested at times that corresponded roughly with the start, middle, and end of the plant reproductive phase. Harvested material was dissected into a number of plant components that were analyzed for peramine concentration by HPLC. All clippings from the V clones were also analyzed. Peramine concentrations were usually similar in leaf sheaths and leaf blades, but they decreased as leaf age increased. The seed from R clones and younger sheaths and blades of leaves from vegetative tillers contained the highest concentrations, while the root, crown, and dead leaf tissue contained the lowest. During the inflorescence phase, tissues from reproductive tillers generally contained lower concentrations than corresponding tissues from vegetative tillers. Also at this time, mean peramine concentrations were higher in V clones than in R clones. By the end of the plant reproductive phase, at the mature seed stage, mean peramine concentrations in R and V clones were similar. The seed component, which contained approximately 75% of the total peramine present in the plant (at a mean concentration of 63.7 μg/g), probably accounted for much of the recovery in the R clones.     

Distribution and Accumulation of the Mycotoxin Lolitrem B in Neotyphodium lolii- Infected Perennial Ryegrass

The symbiotic relationship between perennial ryegrass and its endophytic fungus, Neotyphodium lolii, is of considerable agronomic significance in New Zealand. Livestock ingesting N. lolii-infected perennial ryegrass may succumb to a neuromuscular condition, ryegrass staggers, the probable cause of which has been identified as the endophyte-produced indole–diterpenoid mycotoxin lolitrem B. The effects of plant component, plant reproductive development, and plant management (clipping) on the concentration and accumulation of lolitrem B were investigated. Eight different naturally occurring perennial ryegrass–N. lolii associations were cloned. They were either trimmed regularly to maintain their vegetative state (V clones) or not trimmed at all to enable full plant reproductive development (R clones). At times that corresponded approximately with the start, middle, and end of the plant reproductive phase, V and R clones of each grass–endophyte association were destructively harvested. After dissection into a number of plant components, harvested material was analyzed for lolitrem B content by HPLC. Analyses were also performed on all clippings taken from the V clones. Highest lolitrem B concentrations in vegetative parts were found in older leaf sheaths and dead leaves. Towards the end of the plant reprodutive phase, dead leaves also contained a large proportion of the total lolitrem B content of the V clones. The highest concentration of lolitrem B was found in the seed, which accounted for nearly 60% of the total quantity in R clones. Leaf blades, young leaf sheaths, roots, and crowns generally contained low to moderate concentrations. In late spring, mean concentrations in R and V clones were similar. By the time mature seed was present (mid-summer), mean concentrations in R clones were three times higher than in V clones. This difference was attributed largely to the contribution by the seed in the R clones. The implications of these findings in relation to ryegrass staggers in livestock are discussed.