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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Home | Pregnancy Timeline | News Alerts |News Archive Sep 13, 2013

 

Dravet Foundation

Dravet syndrome, also known as Severe Myoclonic Epilepsy of Infancy (SMEI),
is a rare and catastrophic form of intractable epilepsy that begins in infancy.
Initial seizures are most often prolonged events and in the second year of life
other seizure types begin to emerge. Development remains on track initially,
with plateaus and a progressive decline typically beginning in the second year of life.

See more at: http://www.dravetfoundation.org/dravet-syndrome/what-is-dravet-syndrome#sthash.OSg01f3J.dpuf






zebra fish in lab


Zebra fish in Baraban laboratory

WHO Child Growth Charts

 

 

 

Potential epilepsy drug discovered

An antihistamine discovered in the 1950s to treat itching may also prevent seizures in an intractable form of childhood epilepsy, according to researchers at University of California San Francisco who tested it in zebrafish bred to mimic the disease.

Researchers say their unexpected discovery offers a glimmer of hope for families of children with Dravet Syndrome, a rare genetic disorder that manifests in early childhood with disabling, lifelong consequences. These include dozens, if not hundreds, of daily seizures, as well as profound cognitive and social deficits.

“It is very unfortunate for these children and families, as they often live from seizure to seizure,” explains Scott C. Baraban, PhD, lead author of the article, University of Calfornia San Francisco (UCSF) William K. Bowes Jr. Endowed Chair in Neuroscience Research and professor of Neurological Surgery.

Small, translucent and easy to breed, zebrafish are increasingly being used in place of rodents to screen drugs for rare genetic disorders. But no one had used them for epilepsy drug screening until Baraban’s team found zebrafish with a genetic mutation identical to the one that causes Dravet Syndrome.

Baraban said his method of drug discovery could be used to screen drugs for any form of epilepsy caused by mutations in a single gene – a number of which were recently discovered in another UCSF study on epilepsy. The finding is described in a paper published online in Nature Communications on Sept. 4.


Dravet Syndrome usually develops because of mutations in the SCN1A gene, which codes for proteins in sodium ion channels.

These channels act as pores that allow charged ions to pass through the membranes of neurons and regulate how they fire. In Dravet Syndrome, these channels let in too many ions and the neurons fire excessively, causing seizures.

Other forms of genetically-caused epilepsy involve similar problems in potassium and calcium channels.

While some adult forms of epilepsy can be treated by surgically removing small areas of electrically malfunctioning brain tissue, genetic forms of epilepsy cannot, because they involve neurons all over the brain.

Instead, researchers are focusing their efforts on finding effective drugs.


Baraban’s team discovered the efficacy of clemizole, which had previously been used only as an antihistamine and an antiviral drug, by accident. Since antihistamines can make seizures worse, it’s unlikely he would have focused on the drug if he hadn’t used a study design intended to circumvent bias about which drugs might work. Instead of beginning with a hypothesis based on previous findings, Baraban used a random assortment of 320 compounds in a chemical library of drugs that had already been approved by the Food and Drug Administration. He did not look to see what the drugs were until after he had his results.

Why clemizole works is still a mystery. Baraban’s group tried 10 other antihistamines, four mentioned in the paper and six others since then, and none blocked seizures. Baraban concluded that the antihistamine itself was probably not the mechanism of the drug’s anti-seizure effect and plans future studies to try to figure this out.


This study used mutant zebrafish discovered a few years ago by then-UCSF neuroscientist, Herwig Baier, PhD, now at the Max Planck Institute of Neurobiology in Germany.

By chance, one strain of the fish had a mutation in the same sodium channel gene as the one implicated in Dravet Syndrome.


Just like people with Dravet Syndrome, the fish with this mutation had spontaneous seizures that did not respond to many drugs used to treat epilepsy. But they did respond to a form of the ketogenic – or high-fat – diet, which also often helps reduce seizures in children with Dravet Syndrome. The mutant fish also showed the same developmental pattern as children, whose seizures do not begin until after their first year. In fish, seizures began three days after fertilization. The fish typically died at 10 or 12 days. People with Dravet Syndrome are also vulnerable to sudden unexpected death in epilepsy—SUDEP.

In these studies, Baraban and colleagues worked with larvae no larger than a human eyelash. They measured their brain activity with a micro-electrode just 1 micron in diameter and tracked their tiny, convulsive movements with special software. He said the seizures in these mutant fish closely resembled those in humans with Dravet Syndrome. Since the larvae are so small and easy to work with, they can screen five times as many drugs in his small laboratory as a much larger lab can do with rodents.

Baraban said that it’s important to use whole animals in screening drugs for epilepsy, since it arises from the activity of neural circuits containing many thousands of cells. Even so, his team plans to conduct lab studies to test clemizole’s effect on individual neurons generated from patients with Dravet syndrome. They’ll use induced Pluripotent Stem Cell (iPSC) technology, which involves generating individual neurons from patients with Dravet syndrome, as a preliminary step before testing the drug in people.

Abstract
Dravet syndrome is a catastrophic pediatric epilepsy with severe intellectual disability, impaired social development and persistent drug-resistant seizures. One of its primary monogenic causes are mutations in Nav1.1 (SCN1A), a voltage-gated sodium channel. Here we characterize zebrafish Nav1.1 (scn1Lab) mutants originally identified in a chemical mutagenesis screen. Mutants exhibit spontaneous abnormal electrographic activity, hyperactivity and convulsive behaviours. Although scn1Lab expression is reduced, microarray analysis is remarkable for the small fraction of differentially expressed genes (~3%) and lack of compensatory expression changes in other scn subunits. Ketogenic diet, diazepam, valproate, potassium bromide and stiripentol attenuate mutant seizure activity; seven other antiepileptic drugs have no effect. A phenotype-based screen of 320 compounds identifies a US Food and Drug Administration-approved compound (clemizole) that inhibits convulsive behaviours and electrographic seizures. This approach represents a new direction in modelling pediatric epilepsy and could be used to identify novel therapeutics for any monogenic epilepsy disorder.

Baraban is a member of the Eli & Edythe Broad Center of Regeneration Medicine and Stem Cell Research. Other authors of the article, “Drug screening in Scn1a zebrafish mutant identifies clemizole as a potential Dravet syndrome treatment,” include senior staff research associate Matthew T. Dinday, BA, and Gabriela A. Hortopan, PhD, a postdoctoral fellow. Both work in Baraban’s Epilepsy Research Laboratory.

The research was funded by an Exceptional, Unconventional Research Enabling Knowledge Acceleration (EUREKA) grant from the National Institute of Neurological Disorders and Stroke, the Dravet Syndrome Foundation and Citizens United for Research in Epilepsy.

The UCSF Office of Innovation, Technology and Alliances filed a provisional patent on use of the compound to treat epilepsy.

UCSF is a leading university dedicated to promoting health worldwide through advanced biomedical research, graduate-level education in the life sciences and health professions, and excellence in patient care. It includes top-ranked graduate schools of dentistry, medicine, nursing and pharmacy, a graduate division with nationally renowned programs in basic biomedical, translational and population sciences, as well as a preeminent biomedical research enterprise and two top-ranked hospitals, UCSF Medical Center and UCSF Benioff Children’s Hospital.

Original press releas:http://www.ucsf.edu/news/2013/08/108521/potential-epilepsy-drug-discovered-using-zebrafish