Search

1. Mesotrophic lakes are a threatened habitat in the United Kingdom (UK), and are specified within the UK Biodiversity Action Plan (UKBAP) as requiring protection. Lough Melvin is a large mesotrophic lake that is of particular interest owing to the genetic diversity of its brown trout, but it is currently showing signs of nutrient enrichment. 2. In 1990, average lake total phosphorus (TP) was less than 19 µg P L-1 but increased to 29.5 µg P L-1 by July 2001. Inflow TP also increased from 34 µg P L-1 to 41 µg P L-1 over the same period. Neither phosphorus nor nitrogen appeared to be limiting. 3. Despite higher lake TP, annual chlorophyll a did not increase, remaining less than 5 µg L-1. The phytoplankton was dominated by cyanobacteria and seems to have remained unchanged since the 1950s. Rotifer numbers increased significantly after 2001 but the macro-zooplankton did not. The absence of a phytoplankton response to P enrichment is attributed to light limitation caused by peat staining and thorough mixing. 4. In the catchment, an accelerated programme of clear-felling began in 1999. Recent changes in the lake are consistent with the known impacts of clear-felling conifers on peat soils, namely larger P and dissolved organic carbon (DOC) losses. The latter was reflected in a lower Secchi depth and an enhanced microbial food-web supporting a larger rotifer population. 5. It is suggested that, for the purposes of the Water Framework Directive (WFD), Lough Melvin and other large, alkaline but peat-stained lakes may be treated as a distinct lake type as they do not fit easily into the conventional classifications of dystrophic or mesotrophic lakes. [ABSTRACT FROM AUTHOR]

Objective: To assess the effect of different doses of gabapentin (GBP) on cognitive function in treated epileptic patients.Methods: Twenty seven patients with refractory partial seizures commenced a double blind, dose ranging, placebo controlled, crossover study of adjuvant GBP. Each treatment phase lasted three months, during which the dose of GBP or matched placebo was increased stepwise at intervals of four weeks (1200 mg/day, 1800 mg/day, and 2400 mg/day in three daily doses). Psychomotor and memory testing was carried out at the end of each four week period, at which time the patient also completed subjective measures of cognition, fatigue, worry, temper, and dysphoria. A visual analogue scale was used to assess drowsiness and a questionnaire was employed to gauge the severity of side effects.Results: In the 21 patients completing the study, GBP produced a significant reduction in median monthly seizure frequency from 7 to 4.3 (P = 0.02), the decrease being most pronounced for secondarily generalised seizures (from 1.0 to 0.3, P = 0.01). Forty three per cent of patients reported a reduction in seizure frequency of at least 50% throughout all GBP doses. Mean (SD) plasma concentrations of GBP at 1200, 1800, and 2400 mg/day were 4.7 (2.6), 6.8 (3.8), and 8.6 (3.3) mg/l respectively. The drug had no effect on composite psychomotor and memory scores; nor was there alteration in any self assessment subscore. The mean drowsiness (P = 0.03) score was higher during treatment with 2400 mg GBP daily compared with matched placebo. Composite psychomotor (r = -0.47, P < 0.01), tiredness (r = 0.42, P < 0.01), and side effect (r = 0.61, P < 0.001) scores correlated significantly with seizure frequency but not with GBP dose.Conclusion: GBP is a well tolerated and effective antiepileptic drug which had no measurable effect on cognition but did produce sedation at the highest dose. This study also supports the suggestion that seizures can cause cognitive impairment. [ABSTRACT FROM AUTHOR]