Excessive daytime sleepiness is common, 1 yet opportunities to learn about sleep medicine in medical school are rare; a survey in 1998 indicated that undergraduate courses devoted a median of five minutes to sleep and its disorders.2 In this review we provide an update on the biology, diagnosis, and management of narcolepsy-an important, yet often misdiagnosed, cause of sleepiness that has seen exciting recent advances. We also briefly outline the other principal causes of daytime sleepiness and aim to equip the general reader with a practical approach to the assessment of patients who complain of excessive daytime sleepiness. Sources and selection criteriaThis paper is based on a literature search conducted to produce evidence based guidelines on the diagnosis and management of narcolepsy in adults and children. 3 We searched Medline, Embase, the Cochrane Collaboration, and two specialist sleep literature resources for abstracts with the key word "narcolepsy." We read the full text of relevant papers and hand searched these for other relevant material. A multidisciplinary working party prepared the guidelines, and a group of 10 independent experts later reviewed them. These guidelines can be downloaded from the news section of www.sleeping.org.uk (accessed July 2004).
Lithium succinate and seborrhoeic dermatitis: an antifungal mode of action?SIR, Recent reports have demonstrated that topical application of an 8% lithium succinate ointment is of therapeutic value in the treatment of seborrhoeic dermatitis (SD).''^ Many recent studies have implicated Malassezia furfur (formerly Pityrosporum spp.) in the pathogenesis of SD by demonstrating the clinical efficacy of anti-fungal therapy,'* but Boyle and colleagues reported that lithium succinate had no effect on the growth of seven M. furfur isolates when it was tested in vitro at concentrations of 1-150 mg/1.' It is likely, however, that topical application of 8% lithium succinate ointment will result in local concentrations far in excess of 150 mg/1 (approximately i mM). Moreover, strains of several species of yeast have been reported to be sensitive to 2-30 mM lithium, which inhibited protein and RNA synthesis.' We have therefore investigated the response oiM. furfur isolates to higher concentrations of lithium succinate.Twelve strains of M. furfur were tested by inoculation on to the surface of a lipid-enriched peptoneglucose medium* into which were incorporated dilutions of a filter-sterilized solution of lithium succinate to give final concentrations of 1-5-100 mM. Inocula consisted of 125 ^1 of moderately turbid suspensions (1-5 X io' cfu/ml) of 9-day cultures of various laboratory isolates. For comparative purposes the inhibitory activities of lithium chloride and sodium succinate were also assessed. Minimum inhibitory concentrations (MICs) were defined as the lowest concentrations at which there was either no growth or a barely visible film of growth after 7 days aerobic incubation at 34°C.Results varied markedly among different morphological groups of M. furfur. Large colony strains which predominate on the skin of the upper trunk^ yielded lithium succinate MICs of 100 mM (one strain) or 50 mM (four strains). Small and medium-sized colony strains, which predominate particularly at sites on the head, were more sensitive, with MICs of 6 mM (four strains) or 3 mM (three strains). Parallel determinations of lithium chloride and sodium succinate MICs indicated that lithium was the active moiety.These results indicate that the M. furfur strains most prevalent on the head, the primary site of SD, are inhibited by lithium succinate at concentrations approximately 100-fold less than those available in an 8% ointment. This provides a possible explanation for the efficacy of lithium succinate in SD. The in vivo response of M. furfur to lithium succinate is currently being monitored in extended trials to further test this hypothesis.
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