This paper is aimed at understanding epileptic patient disorders through the analysis of surface electroencephalograms (EEG). It deals with the detection of spikes or spike-waves based on a nonorthogonal wavelet transform. A multilevel structure is described that locates the temporal segments where abnormal events occur. These events are then visually interpreted by means of a 3D mapping technique. This 3D display makes use of a ray tracing scheme and combines both the functional (the EEG but also its wavelet representation) and the morphological data (acquired from computed tomography [CT] or magnetic resonance imaging [MRI] devices). The results show that a significant reduction of the clinical workload is obtained while the most important episodes are better reviewed and analyzed.

Algorithms↗

PubMedDate not supplied

Pre-ictal synchronicity in limbic networks of mesial temporal lobe epilepsy.

PURPOSE: We recorded with intracerebral electrodes the onset of limbic seizures in patients with mesial temporal lobe epilepsy (MTLE) to identify the dynamic interactions between the hippocampus (HIP), amygdala (AMY) and entorhinal cortex (EC). METHODS: Interactions were quantified by analyzing the interdependencies between stereo-electroencephalographic (SEEG) signals using a nonlinear cross-correlation method. Seizures from 12 patients were analyzed by identifying three periods of interest: (i) the rapid discharge that occurs at seizure onset ("during rapid discharge", DRD period); (ii) the time interval that precedes this rapid discharge ("before rapid discharge", BRD period); and the time that follows the rapid discharge ("after rapid discharge", ARD period). The transition from interictal to ictal discharge was classified into: (i) "type 1 transition" in which the emergence of pre-ictal spiking was followed by a rapid discharge; and (ii) "type 2 transition" that was associated with rapid discharge onset without prior spiking. RESULTS: In both types of transition the BRD period was characterized by significant cross-correlation values indicating strong interactions among mesial temporal structures as compared to those seen during background activity. Interactions between HIP and EC were predominant in 10 of 12 patients (83%). Interactions between EC and AMY were observed in 6 of 12 cases (50%) and between AMY and HIP in 7 of 12 cases (58%). Analysis of coupling directionality indicated that most of the couplings were driven either by HIP (six patients) or by the EC (four patients). The DRD period was characterized by a significant decrease of cross-correlation values. In addition, type 1 transition was characterized by interactions that uniformly involved the three structures, while type 2 transition was associated with interactions between EC and HIP. Finally, analysis of coupling direction demonstrated that the HIP was always the leader in type 1 transition whereas in type 2 the EC was most often the leading structure. CONCLUSIONS: This study demonstrates that pre-ictal synchronization between mesial structures is the initial event for seizures starting in the mesial temporal region.

Adolescent↗

PubMedDate not supplied

Long-term culture of murine erythropoietic progenitor cells in the absence of an adherent layer.

Replication of multipotential stem cells in long-term murine bone marrow cell culture is known to depend on the development of an adherent stromal cell layer. In these conditions, restricted haematopoietic progenitor cells have also been generated for up to several months1-3. However, maturation is observed only in the granulocyte/macrophage and megakaryocyte lineages; erythropoiesis appears to be blocked at the earliest burst-forming unit (BFU-E) stage. Addition of exogenous erythropoietin (Epo) or anaemic mouse serum results in full erythropoietic maturation, but it is transient. We describe here a culture system in which production of erythropoietic progenitor cells can be maintained for over 6 months in the absence of an adherent stromal layer and in the absence of added Epo, but in the presence of pokeweed mitogen-stimulated spleen cell conditioned medium (PWSCM). The data indicate that restricted erythroid progenitor cells exist which are capable of extensive self-renewal.

Animals↗

PubMedDate not supplied

Fertile dominant spotting in the house mouse.

Recognition of a new allele (Wf) at the W locus of the mouse is based on genetic analysis and demonstration of defective hair pigmentation, macrocytic anemia, and defects in pluripotent hemopoietic stem cells. Unlike other alleles of the W series, this one does not result in sterility.

Alleles↗

PubMedDate not supplied

Adenoviral supply of active transforming growth factor-beta1 (TGF-beta1) did not prevent lethality in transforming growth factor-beta1-knockout embryos.

In TGF-beta1-knockout mice, TGF-beta1-null conceptuses die during embryonic development with a penetrance of lethality that depends on the mouse genetic background. Studies have suggested that transplacental passage of maternal TGF-beta1 could account for the rescue of some TGF-beta1-null embryos. Herein, we have used an adenovirus-based gene delivery system and a strain of mice where most TGF-beta1-null conceptuses die prior to parturition, to investigate whether an increase in maternal TGF-beta1 during pregnancy would rescue TGF-beta1-null embryos. A single intravenous injection of an adenovirus containing a modified version of TGF-beta1 cDNA (Ad-TGF-beta1S223/S225), coding for a biologically active form of the cytokine, induced a 20-fold increase in plasma TGF-beta1 (active and latent forms) levels for up to 3 months in adult mice. Similar levels of TGF-beta1 were detected in 13-day post coïtum (dpc) embryos from Ad-TGF-beta1-treated mothers, demonstrating an efficient maternal/fetal transfer of the cytokine. However, no increase in the frequencies of TGF-beta1-null neonates nor in day 11.5 dpc TGF-beta1-null conceptuses was observed despite elevated levels of TGF-beta1 delivered throughout gestation. In addition, we show that the high levels of TGF-beta1-titrated in the plasma from Ad-TGF-beta1S223/S225-treated mice were partly the consequence of a stimulation of an autocrine production by exogenous bioactive TGF-beta1. These results indicate that transplacental passage of TGF-beta1 was not effective in rescuing TGF-beta1-null conceptuses from embryonic lethality.

Adenoviridae↗

PubMedDate not supplied

[Effect of different erythropoietic homeostasis factors on the evolution of Friend's leukemia].

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Animals↗