Stressed but Stable: Canopy Loss Decreased Species Synchrony and Metabolic Variability in an Intertidal Hard-Bottom Community

The temporal stability of aggregate community properties depends on the dynamics of the component species. Since species growth can compensate for the decline of other species, synchronous species dynamics can maintain stability (i.e. invariability) in aggregate properties such as community abundance and metabolism. In field experiments we tested the separate and interactive effects of two stressors associated with storminess–loss of a canopy-forming species and mechanical disturbances–on species synchrony and community respiration of intertidal hard-bottom communities on Helgoland Island, NE Atlantic. Treatments consisted of regular removal of the canopy-forming seaweed Fucus serratus and a mechanical disturbance applied once at the onset of the experiment in March 2006. The level of synchrony in species abundances was assessed from estimates of species percentage cover every three months until September 2007. Experiments at two sites consistently showed that canopy loss significantly reduced species synchrony. Mechanical disturbance had neither separate nor interactive effects on species synchrony. Accordingly, in situ measurements of CO2-fluxes showed that canopy loss, but not mechanical disturbances, significantly reduced net primary productivity and temporal variation in community respiration during emersion periods. Our results support the idea that compensatory dynamics may stabilise aggregate properties. They further suggest that the ecological consequences of the loss of a single structurally important species may be stronger than those derived from smaller-scale mechanical disturbances in natural ecosystems

A pilot study: portable out-of-center sleep testing as an early sleep apnea screening tool in acute ischemic stroke

Oleg Y Chernyshev,1 David E McCarty,1 Douglas E Moul,2 Cesar Liendo,1 Gloria C Caldito,1 Sai K Munjampalli,1 Roger E Kelley,3 Andrew L Chesson Jr1 1Division of Sleep Medicine, Department of Neurology, Louisiana State University Health Sciences Center at Shreveport, LA 2Sleep Disorders Center, Cleveland Clinic, Cleveland, OH, 3Department of Neurology, Tulane University, New Orleans, LA, USA Introduction: Prompt diagnosis of obstructive sleep apnea (OSA) after acute ischemic stroke (AIS) is critical for optimal clinical outcomes, but in-laboratory conventional polysomnograms (PSG) are not routinely practical. Though portable out-of-center type III cardiopulmonary sleep studies (out-of-center cardiopulmonary sleep testing [OCST]) are widely available, these studies have not been validated in patients who have recently suffered from AIS. We hypothesized that OCST in patients with AIS would yield similar results when compared to conventional PSG. Methods: Patients with AIS had simultaneous type III OCST and PSG studies performed within 72 hours from symptom onset. The accuracy of OCST was compared to PSG using: chi-square tests, receiver operatory characteristic curves, Bland–Altman plot, paired Student's t-test/Wilcoxon signed-rank test, and calculation of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Results: Twenty-one out of 23 subjects with AIS (age 61±9.4 years; 52% male; 58% African-American) successfully completed both studies (9% technical failure). Nearly all (95%) had Mallampati IV posterior oropharynx; the mean neck circumference was 16.8±1.6 in. and the mean body mass index (BMI) was 30±7 kg/m2. The apnea hypopnea index (AHI) provided by OCST was similar to that provided by PSG (19.8±18.0 vs 22.0±22.7, respectively; P=0.49). On identifying subjects by OCST with an AHI ≥5 on PSG, OCST had the following parameters: sensitivity 100%, specificity 85.7%, PPV 93%, and NPV 100%. On identifying subjects with an AHI ≥15 on PSG, OCST parameters were as follows: sensitivity 100%, specificity 83.3%, PPV 81.8%, and NPV 100%. Bland–Altman plotting showed an overall diagnostic agreement between OCST and PSG modalities for an AHI cutoff >5, despite fine-grained differences in estimated AHIs. Conclusion: Compared with PSG, OCST provides similar diagnostic information when run simultaneously in AIS patients. OCST is a reliable screening tool for early diagnosis of OSA in AIS patients. Keywords: portable clinical screening, obstructive sleep apnea diagnosis, acute ischemic stroke, sleep testing in stroke, acute sleep medicin

Neuropsychological sequelae in Kleine-Levin syndrome: case report Sequela neuropsicológica na síndrome de Kleine-Levin: relato de caso

Kleine-Levin syndrome is characterized by periodic hypersomnia, hyperphagia, sexual disinhibitions and behavioral disturbances. The prognosis is generally benign, with normal cognitive and social functions after the episodes. We describe a typical case of Kleine-Levin syndrome associated with apparent academic decline, neuropsychological sequelae and personality alterations after the second episode of the illness. Further research in the natural history of Kleine-Levin syndrome is needed, for example, to determine whether early intervention would improve long-term prognosis.<br>A síndrome de Kleine-Levin é caracterizada por hipersônia periódica, hiperfagia, desinibição sexual e outras alterações do comportamento. O prognóstico é geralmente benigno, com funções cognitivas e sociais normais após os episódios. Descrevemos um caso típico de síndrome de Kleine-Levin associada com declínio acadêmico, sequela neuropsicológica e alterações da personalidade após o segundo episódio da síndrome. Estudos adicionais sobre a história natural da doença são necessários para, por exemplo, determinar se a intervenção terapêutica precoce melhoraria o prognóstico a longo prazo