8,434 research outputs found

    Epigenetic suppression of hippocampal calbindin-D28k by ΔFosB drives seizure-related cognitive deficits.

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    The calcium-binding protein calbindin-D28k is critical for hippocampal function and cognition, but its expression is markedly decreased in various neurological disorders associated with epileptiform activity and seizures. In Alzheimer\u27s disease (AD) and epilepsy, both of which are accompanied by recurrent seizures, the severity of cognitive deficits reflects the degree of calbindin reduction in the hippocampal dentate gyrus (DG). However, despite the importance of calbindin in both neuronal physiology and pathology, the regulatory mechanisms that control its expression in the hippocampus are poorly understood. Here we report an epigenetic mechanism through which seizures chronically suppress hippocampal calbindin expression and impair cognition. We demonstrate that ΔFosB, a highly stable transcription factor, is induced in the hippocampus in mouse models of AD and seizures, in which it binds and triggers histone deacetylation at the promoter of the calbindin gene (Calb1) and downregulates Calb1 transcription. Notably, increasing DG calbindin levels, either by direct virus-mediated expression or inhibition of ΔFosB signaling, improves spatial memory in a mouse model of AD. Moreover, levels of ΔFosB and calbindin expression are inversely related in the DG of individuals with temporal lobe epilepsy (TLE) or AD and correlate with performance on the Mini-Mental State Examination (MMSE). We propose that chronic suppression of calbindin by ΔFosB is one mechanism through which intermittent seizures drive persistent cognitive deficits in conditions accompanied by recurrent seizures

    Acute and long-term effects of brivaracetam and brivaracetam-diazepam combinations in an experimental model of status epilepticus.

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    ObjectiveTo evaluate acute and long-term effects of intravenous brivaracetam (BRV) and BRV + diazepam (DZP) combination treatment in a rat model of self-sustaining status epilepticus (SSSE).MethodsRats were treated with BRV (10 mg/kg) 10 min after initiation of perforant path stimulation (PPS) as early treatment; or BRV (10-300 mg/kg), DZP (1 mg/kg), or BRV (0.3-10 mg/kg) + DZP (1 mg/kg) 10 min after the end of PPS (established SSSE). Seizure activity was recorded electrographically for 24 h posttreatment (acute effects), and for 1 week at 6-8 weeks or 12 months' posttreatment (long-term effects). All treatments were compared with control rats using one-way analysis of variance (ANOVA) and Bonferroni's test, or Kruskal--Wallis and Dunn's multiple comparison tests, when appropriate.ResultsTreatment of established SSSE with BRV (10-300 mg/kg) resulted in dose-dependent reduction in SSSE duration and cumulative seizure time, achieving statistical significance at doses ≥100 mg/kg. Lower doses of BRV (0.3-10 mg/kg) + low-dose DZP (1 mg/kg) significantly reduced SSSE duration and number of seizures. All control rats developed spontaneous recurrent seizures (SRS) 6-8 weeks after SSSE, whereas seizure freedom was noted in 2/10, 5/10, and 6/10 rats treated with BRV 200 mg/kg, 300 mg/kg, and BRV 10 mg/kg + DZP, respectively. BRV (10-300 mg/kg) showed a dose-dependent trend toward reduction of SRS frequency, cumulative seizure time, and spike frequency, achieving statistical significance at 300 mg/kg. Combination of BRV (10 mg/kg) + DZP significantly reduced SRS frequency, cumulative seizure time, and spike frequency. In the 12-month follow-up study, BRV (0.3-10 mg/kg) + low-dose DZP markedly reduced SRS frequency, cumulative seizure time, and spike frequency, achieving statistical significance at some doses. Early treatment of SSSE with BRV 10 mg/kg significantly reduced long-term SRS frequency.SignificanceThese findings support clinical evaluation of BRV for treatment of status epilepticus or acute repetitive seizures

    ΔFosB Regulates Gene Expression and Cognitive Dysfunction in a Mouse Model of Alzheimer\u27s Disease.

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    Alzheimer\u27s disease (AD) is characterized by cognitive decline and 5- to 10-fold increased seizure incidence. How seizures contribute to cognitive decline in AD or other disorders is unclear. We show that spontaneous seizures increase expression of ΔFosB, a highly stable Fos-family transcription factor, in the hippocampus of an AD mouse model. ΔFosB suppressed expression of the immediate early gene c-Fos, which is critical for plasticity and cognition, by binding its promoter and triggering histone deacetylation. Acute histone deacetylase (HDAC) inhibition or inhibition of ΔFosB activity restored c-Fos induction and improved cognition in AD mice. Administration of seizure-inducing agents to nontransgenic mice also resulted in ΔFosB-mediated suppression of c-Fos, suggesting that this mechanism is not confined to AD mice. These results explain observations that c-Fos expression increases after acute neuronal activity but decreases with chronic activity. Moreover, these results indicate a general mechanism by which seizures contribute to persistent cognitive deficits, even during seizure-free periods

    Representative Defendants

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    Everyone except the defendant in a criminal proceeding somehow represents the people. Prosecutors, judges, and juries are all considered public agents. Defendants in contrast are thought of as parochial, interested in nothing more than saving their own skins. This broadly shared understanding of criminal court actors was not historically fated nor is it legally accurate today. The Constitution tasks criminal defendants with significant public responsibility. They frequently represent the interests of third parties who have no direct stake in defendants\u27 criminal cases. Defendants vindicate the participatory rights of excluded jurors, they deter unconstitutional searches and seizures that could harm innocent civilians in the future, and they help ensure the transparent and expeditious functioning of the criminal justice system for the public\u27s benefit. Neither courts nor commentators recognize these representative actions as part of a coherent account of defendants\u27 role in the legal system. But representative defendants serve some of the same functions that representative plaintiffs do in the civil setting: overcoming information deficits, low-dollar-value harms, and resource scarcity, all of which make it unlikely that individual harm bearers will seek recourse in court. Courts, commentators, and the public should be clear-eyed about the role defendants play in our legal system. Doing so would help modulate criminal justice policy and enable defense counsel to more effectively challenge the systematic, third-party harms that criminal justice institutions generate

    Justice Visualized: Courts and the Body Camera Revolution

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    What really happened? For centuries, courts have been magisterially blind, cloistered far away from the contested events that they adjudicate, relying primarily on testimony to get the story—or competing stories. Whether oral or written, this testimony is profoundly human, with all the passions, partisanship and imperfections of human perception. Now a revolution is coming. Across the nation, police departments are deploying body cameras. Analyzing body camera policies from police departments across the nation, the article reveals an unfolding future where much of the main staple events of criminal procedure law will be recorded. Much of the current focus is on how body cameras will impact policing and public opinion. Yet there is another important audience for body camera footage—the courts that forge constitutional criminal procedure, the primary conduct rules for police. This article explores what the coming power to replay a wider array of police enforcement actions than ever before means for judicial review and criminal procedure law. The body camera revolution means an evidentiary revolution for courts, transforming the traditional reliance on reports and testimony and filling in gaps in a domain where defendants are often silent. The article proposes rules of judicial review to cultivate regular use of the audiovisual record in criminal procedure cases and discourage gaps and omissions due to selective recording. The article also offers rules of restraint against the seductive power of video to seem to depict the unmediated truth. Camera perspective can subtly shape judgments. Personal worldviews influence image interpretation. And there is often a difference between the legally relevant truth and the depiction captured on video. Care must be taken therefore to apply the proper perceptual yardsticks and reserve interpretive questions for the appropriate fact-finders

    The Long Road to Justice: Why State Courts Should Lower the Evidentiary Burden for Proving Racialized Traffic Stops and Adopt the Exclusionary Rule as a Remedy for Equal Protection Violations

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    Racist and brutal policing continues to pervade the criminal legal system. Black and brown people who interact with the police consistently face unequal targeting and treatment. Routine traffic stops are especially dangerous and harmful and can lead to death. Under Whren, a police officer’s racist motivations or implicit bias towards a driver do not influence the constitutionality of a traffic stop. An officer only needs to show there was probable cause to believe a traffic stop occurred. Although the unconstitutionality of pre-textual traffic stops has been widely explored since Whren, both federal and state courts have struggled to find legal solutions that fight back against a doctrine that fails to protect minority drivers. This note explores those failed solutions and argues that state courts have a legal obligation to both ease the burden of proving an equal protection violation and recognize the exclusionary rule as a remedy for those violations. As long as Whren is good law, state courts must get creative in the fight against racist policing and the selective prosecution of traffic laws

    Osmotic Edema Rapidly Increases Neuronal Excitability Through Activation of NMDA Receptor-Dependent Slow Inward Currents in Juvenile and Adult Hippocampus.

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    Cellular edema (cell swelling) is a principal component of numerous brain disorders including ischemia, cortical spreading depression, hyponatremia, and epilepsy. Cellular edema increases seizure-like activity in vitro and in vivo, largely through nonsynaptic mechanisms attributable to reduction of the extracellular space. However, the types of excitability changes occurring in individual neurons during the acute phase of cell volume increase remain unclear. Using whole-cell patch clamp techniques, we report that one of the first effects of osmotic edema on excitability of CA1 pyramidal cells is the generation of slow inward currents (SICs), which initiate after approximately 1 min. Frequency of SICs increased as osmolarity decreased in a dose-dependent manner. Imaging of real-time volume changes in astrocytes revealed that neuronal SICs occurred while astrocytes were still in the process of swelling. SICs evoked by cell swelling were mainly nonsynaptic in origin and NMDA receptor-dependent. To better understand the relationship between SICs and changes in neuronal excitability, recordings were performed in increasingly physiological conditions. In the absence of any added pharmacological reagents or imposed voltage clamp, osmotic edema induced excitatory postsynaptic potentials and burst firing over the same timecourse as SICs. Like SICs, action potentials were blocked by NMDAR antagonists. Effects were more pronounced in adult (8-20 weeks old) compared with juvenile (P15-P21) mice. Together, our results indicate that cell swelling triggered by reduced osmolarity rapidly increases neuronal excitability through activation of NMDA receptors. Our findings have important implications for understanding nonsynaptic mechanisms of epilepsy in relation to cell swelling and reduction of the extracellular space
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