LGI1-negative faciobrachial dystonic-like seizures originating from the insula

AbstractWe expand the differential diagnosis of LGI1-positive faciobrachial dystonic seizures (FBDS) by presenting a 67-year-old woman affected by seizures of similar semiology who was found to have insular epilepsy. We report the distinct characteristics of insular faciobrachial dystonic-like seizures that would help clinicians to differentiate them from typical LGI1-positive FBDS, thus, guiding therapy while awaiting antibody results. LGI1-negative faciobrachial dystonic-like seizures should be considered when the seizure semiology includes unilateral and prolonged dystonia without loss of awareness, there is an ictal EEG correlate, MRI is suggestive of insular lesion, and when there is neither clearly associated memory impairment nor hyponatremia

Reconciliation of the carbon budget in the ocean’s twilight zone

Photosynthesis in the surface ocean produces approximately 100 gigatonnes of organic carbon per year, of which 5 to 15 per cent is exported to the deep ocean1, 2. The rate at which the sinking carbon is converted into carbon dioxide by heterotrophic organisms at depth is important in controlling oceanic carbon storage3. It remains uncertain, however, to what extent surface ocean carbon supply meets the demand of water-column biota; the discrepancy between known carbon sources and sinks is as much as two orders of magnitude4, 5, 6, 7, 8. Here we present field measurements, respiration rate estimates and a steady-state model that allow us to balance carbon sources and sinks to within observational uncertainties at the Porcupine Abyssal Plain site in the eastern North Atlantic Ocean. We find that prokaryotes are responsible for 70 to 92 per cent of the estimated remineralization in the twilight zone (depths of 50 to 1,000 metres) despite the fact that much of the organic carbon is exported in the form of large, fast-sinking particles accessible to larger zooplankton. We suggest that this occurs because zooplankton fragment and ingest half of the fast-sinking particles, of which more than 30 per cent may be released as suspended and slowly sinking matter, stimulating the deep-ocean microbial loop. The synergy between microbes and zooplankton in the twilight zone is important to our understanding of the processes controlling the oceanic carbon sink

Controls over Ocean Mesopelagic Interior Carbon Storage (COMICS): Fieldwork, Synthesis, and Modeling Efforts

The ocean's biological carbon pump plays a central role in regulating atmospheric CO2 levels. In particular, the depth at which sinking organic carbon is broken down and respired in the mesopelagic zone is critical, with deeper remineralization resulting in greater carbon storage. Until recently, however, a balanced budget of the supply and consumption of organic carbon in the mesopelagic had not been constructed in any region of the ocean, and the processes controlling organic carbon turnover are still poorly understood. Large-scale data syntheses suggest that a wide range of factors can influence remineralization depth including upper-ocean ecological interactions, and interior dissolved oxygen concentration and temperature. However, these analyses do not provide a mechanistic understanding of remineralization, which increases the challenge of appropriately modeling the mesopelagic carbon dynamics. In light of this, the UK Natural Environment Research Council has funded a programme with this mechanistic understanding as its aim, drawing targeted fieldwork right through to implementation of a new parameterization for mesopelagic remineralization within an IPCC class global biogeochemical model. The Controls over Ocean Mesopelagic Interior Carbon Storage (COMICS) programme will deliver new insights into the processes of carbon cycling in the mesopelagic zone and how these influence ocean carbon storage. Here we outline the programme's rationale, its goals, planned fieldwork, and modeling activities, with the aim of stimulating international collaboration

Disabling amnestic syndrome following stereotactic laser ablation of a hypothalamic hamartoma in a patient with a prior temporal lobectomy

A 19-year-old man with cortical dysplasia and intractable focal seizures underwent a right temporal lobectomy. A hypothalamic hamartoma was subsequently recognized, and he then underwent MRI-guided stereotactic laser ablation. Unfortunately, he sustained damage to the bilateral medial mammillary bodies and suffered significant memory loss. We review laser ablation therapy for hypothalamic hamartomas and the anatomy of the memory network. We postulate that his persistent memory disorder resulted from a combination of the right temporal lobectomy and injury to the bilateral medial mammillary bodies

Occipital dysembryoplastic neuroepithelial tumor presenting as adult-onset temporal epilepsy

Dysembryoplastic neuroepithelial tumor (DNET) is a benign brain tumor which commonly presents as childhood-onset temporal lobe epilepsy (TLE). We present a case of histologically proven DNET with a clinical presentation and scalp EEG suggestive of adult-onset TLE. MRI showed an occipital lesion. PET showed abnormal metabolism of the occipital lesion and the ipsilateral temporal lobe; raising concern for an abnormal functional network reorganization. Intracranial EEG showed interictal spikes and seizures originating from the occipital lesion with no seizures emanating from the temporal lobe. Occipital DNET due to their chronic nature can reorganize the network and mimic TLE

Occipital dysembryoplastic neuroepithelial tumor presenting as adult-onset temporal epilepsy.

Dysembryoplastic neuroepithelial tumor (DNET) is a benign brain tumor which commonly presents as childhood-onset temporal lobe epilepsy (TLE). We present a case of histologically proven DNET with a clinical presentation and scalp EEG suggestive of adult-onset TLE. MRI showed an occipital lesion. PET showed abnormal metabolism of the occipital lesion and the ipsilateral temporal lobe; raising concern for an abnormal functional network reorganization. Intracranial EEG showed interictal spikes and seizures originating from the occipital lesion with no seizures emanating from the temporal lobe. Occipital DNET due to their chronic nature can reorganize the network and mimic TLE

Distinct Seasonal Growth Patterns of the Bacterium Planktotalea frisia in the North Sea and Specific Interaction with Phytoplankton Algae

We investigated the occurrence of Planktotalea frisia strain SH6-1T, a member of the Roseobacter clade, in the North Sea and interactions with phytoplankton algae with a special emphasis on the carbohydrate metabolisms. This bacterium was present in May 2006 throughout the North Sea. P. frisia SH6-1 was further present in the German Bight between February and early July with distinct peaks during and after phytoplankton blooms. Highest abundances, as detected by quantitative PCR, were 0.5-0.9% of total bacterial abundance. Comparison by CARD-FISH with a set of highly specific probes confirmed the high values in one sample. Between mid-July and October, P. frisia SH6-1 was not detected throughout the North Sea. Experimental studies in which P. frisia SH6-1 was grown in the presence of axenic cultures of the algae Phaeocystis globosa, Leptocylindrus danicus and Thalassiosira rotula exhibited distinctly different responses with the best growth together with P. globosa and T. rotula and very low growth together with L. danicus. The algae greatly differed in the composition of their exuded carbohydrates and that P. frisia SH6-1 was rather selective in their consumption, suggesting that the distinct carbohydrate metabolisms is a key feature to explain its seasonal occurrence in the North Sea

Letter. Phosphorus cycling in the North and South Atlantic Ocean subtropical gyres

Despite similar physical properties, the Northern and Southern Atlantic subtropical gyres have different biogeochemical regimes. The Northern subtropical gyre, which is subject to iron deposition from Saharan dust1, is depleted in the nutrient phosphate, possibly as a result of iron-enhanced nitrogen fixation2. Although phosphate depleted, rates of carbon fixation in the euphotic zone of the North Atlantic subtropical gyre are comparable to those of the South Atlantic subtropical gyre3, which is not phosphate limited. Here we use the activity of the phosphorus-specific enzyme alkaline phosphatase to show potentially enhanced utilization of dissolved organic phosphorus occurring over much of the North Atlantic subtropical gyre. We find that during the boreal spring up to 30% of primary production in the North Atlantic gyre is supported by dissolved organic phosphorus. Our diagnostics and composite map of the surface distribution of dissolved organic phosphorus in the subtropical Atlantic Ocean reveal shorter residence times in the North Atlantic gyre than the South Atlantic gyre. We interpret the asymmetry of dissolved organic phosphorus cycling in the two gyres as a consequence of enhanced nitrogen fixation in the North Atlantic Ocean4, which forces the system towards phosphorus limitation. We suggest that dissolved organic phosphorus utilization may contribute to primary production in other phosphorus-limited ocean settings as well

Southern Ocean deep-water carbon export enhanced by natural iron fertilization

The addition of iron to high- nutrient, low- chlorophyll regions induces phytoplankton blooms that take up carbon(1-3). Carbon export from the surface layer and, in particular, the ability of the ocean and sediments to sequester carbon for many years remains, however, poorly quantified(3). Here we report data from the CROZEX experiment(4) in the Southern Ocean, which was conducted to test the hypothesis that the observed north - south gradient in phytoplankton concentrations in the vicinity of the Crozet Islands is induced by natural iron fertilization that results in enhanced organic carbon flux to the deep ocean. We report annual particulate carbon fluxes out of the surface layer, at three kilometres below the ocean surface and to the ocean floor. We find that carbon fluxes from a highly productive, naturally iron-fertilized region of the sub- Antarctic Southern Ocean are two to three times larger than the carbon fluxes from an adjacent high-nutrient, low- chlorophyll area not fertilized by iron. Our findings support the hypothesis that increased iron supply to the glacial sub- Antarctic may have directly enhanced carbon export to the deep ocean(5). The CROZEX sequestration efficiency(6) ( the amount of carbon sequestered below the depth of winter mixing for a given iron supply) of 8,600 mol mol(-1) was 18 times greater than that of a phytoplankton bloom induced artificially by adding iron(7), but 77 times smaller than that of another bloom(8) initiated, like CROZEX, by a natural supply of iron. Large losses of purposefully added iron can explain the lower efficiency of the induced bloom(6). The discrepancy between the blooms naturally supplied with iron may result in part from an underestimate of horizontal iron supply