Fermentation byproduct suppresses seizures in nerve agent poisoning

A compound found in trace amounts in alcoholic beverages is more effective at combating seizures in rats exposed to an organophosphate nerve agent than the current recommended treatment, according to new research published in eNeuro.

This work comes from Asheebo Rojas, Ray Dingledine and colleagues in Emory’s Department of Pharmacology. Just as an aside, we don’t know the nature of the recent alleged chemical attack in Syria, and the chemical used in the Emory experiments is not a “weaponized” nerve agent such as Sarin. Organophosphates were also widely used as insecticides, but their use has been declining.

Left untreated, organophosphate poisoning can lead to severe breathing and heart complications, because of the inhibition of acetylcholinesterase. It also causes seizures. Some patients are resistant to treatment with the anti-anxiety drug diazepam (Valium), a standard first-line treatment for such poisoning, and its effectiveness decreases the longer the seizure lasts.

The researchers compared the ability of two treatments — diazepam and the anesthetic urethane (ethyl carbamate), commonly formed in trace amounts during fermentation of beer and wine from the reaction of urea and ethanol — to interrupt seizures in rats exposed to the organophosphate diisopropyl fluorophosphate. The researchers found urethane to be more effective than diazepam, suppressing seizures for multiple days and accelerating recovery of weight lost while protecting the rats from cell loss in the hippocampus.

Urethane/ethyl carbamate is a carcinogen in animals, which led to concerns over its presence in alcoholic beverages in the 1980s. It was also used as a sedative for many years in Japan. The researchers did not observe any evidence of lung tumors in the urethane-treated animals seven months later, suggesting that the dose used in this study is not carcinogenic. The findings point to urethane or a derivative as a potential therapeutic for preventing organophosphate-triggered seizures from developing into epilepsy. Read more

Posted on April 20, 2018 by Quinn Eastman in Neuro Leave a comment

Post-anesthetic inertia in IH

A recent paper from neurologists Lynn Marie Trotti and Donald Bliwise, with anesthesiologist Paul Garcia, substantiates a phenomenon discussed anecdotally in the idiopathic hypersomnia (IH) community. Let’s call it “post-anesthetic inertia.” People with IH say that undergoing general anesthesia made their sleepiness or disrupted sleep-wake cycles worse, sometimes for days or weeks. This finding is intriguing because it points toward a trigger mechanism for IH. And it pushes anesthesiologists to take IH diagnoses into account when planning patient care, just as is already done for myotonic dystrophy.

Lab Land obtained some confirmation from a couple IHers. One woman had surgery a couple of months ago and felt like the anesthetic was still in her system for weeks and she still didn’t feel right. Another reported “severe insomnia for months and it felt like every body system was completely scrambled.”

Where does this all come from? People with IH getting together and telling their stories. Journalist Virginia Hughes described a moment at the 2014 patient-organized IH meeting in Atlanta in her article “Wake No More”:

Andy Jenkins, the neuroscientist who developed the spinal fluid test, gave an impressively entertaining lecture on GABA receptors. “Why do we have more GABA activity?” somebody asked. Nobody knows, said Jenkins. One idea is that it’s triggered by anesthesia. Lloyd [Johnson, a meeting organizer from Australia] asked the audience how many of them believed their hypersomnia was the result of anesthesia. About one-quarter of the hands went up. “Whoa, whoa, whoa, whoa, whoa,” Jenkins said as he watched the sleepyheads* come alive.

The new paper, in Frontiers in Human Neuroscience, is more quantitative than that informal show of hands. In a way, it begins to question the basis for the term idiopathic hypersomnia, since idiopathic means “arising spontaneously or having no cause”. For some people surveyed in the paper, anesthesia was an exacerbating factor, if not the only factor.

Confusion or agitation post-anesthesia can happen in people who don’t have sleep disorders. What’s peculiar to the hypersomnolent group is how long sleepiness or disrupted sleep-wake cycles last — long after the anesthetic has left the body. The hypersomnolent group was mostly people with IH or narcolepsy type 2 (30 plus 15 out of 57). In the paper, people with restless legs syndrome were used as controls:

While patients in both groups were equally likely to report surgical complications and difficulty awakening from anesthesia, hypersomnolent patients were more likely to report worsened sleepiness (40% of the hypersomnolent group vs. 11% of the RLS group, p = 0.001) and worsening of their sleep disorder symptoms (40% of the hypersomnolent group vs. 9% of the RLS group, p = 0.0001).

Hypersomnolent patients who perceived their symptoms to worsen reported that symptoms had never returned to baseline in 66.7%, took months or years to return to baseline in 9.5%, and resolved in days to weeks in 23.8%.

Note: first author Vincent LaBarbera is now a neurology resident at Brown.

Mechanistic speculation

Several years ago, Emory researchers found that some IH patients appear to have a substance in their cerebrospinal fluid that acts similarly (but not quite the same) as a benzodiazepine drug. This still-mysterious substance enhances signaling by GABA, the major inhibitory neurotransmitter.

Inhaled anesthetics such as sevoflurane, as well as the injected anesthetic propofol, act by enhancing GABA too. So when someone undergoes general anesthesia, their GABA receptors are being pushed hard for an extended period of time. GABA signaling has a kind of global “dimmer switch” function as well as working through specific circuits in the brain to bring on anesthesia.

GABA receptors are complex, but they usually adjust to pressure. It explains development of tolerance to benzodiazepine drugs. GABA receptors also modulate in response to alcohol or women’s menstrual cycles (certain derivatives of progesterone, so-called “neurosteroids,” act on them). What may be happening after anesthesia is that GABA receptors of people with IH have trouble adjusting back, or may overshoot, perhaps because their internal clocks are less resilient.

The Emory authors conclude:

Because the half-life of anesthetic agents is generally short, any prolonged worsening of sleepiness post-procedure cannot easily be attributed to immediate GABA-mediated effects. Whether the putative long-term changes in hypersomnolence that we are detecting in our patients’ reports may be related to changes in GABA-related neural circuitry caused by anesthetic neurotoxicity or other mechanisms remains to be determined.

A similar interaction, with reversed polarity, may be occurring in post-partum depression.

*Lab Land has been told that sleepyhead is not a fully accepted term in the IH community.

Posted on April 20, 2018 by Quinn Eastman in Neuro Leave a comment

How much does idiopathic hypersomnia overlap with ME/CFS?

In everyday linguistic usage among non-specialists, sleepiness can blend together with tiredness and fatigue. Someone might feel “tired” after climbing a mountain or chopping down a tree, while “sleepiness” is different. Emory sleep scientists explore the pathological distinctions in a paper published in Journal of Sleep Research.

A team led by neurologists Lynn Marie Trotti and David Rye has been studying idiopathic hypersomnia (IH) for several years: people who experience excessive daytime sleepiness and “sleep drunkenness,” not explained by other medical conditions.

IH’s symptoms don’t usually include persistent muscle pain or a severe response to exertion. This separates the disorder from myalgic encephalomyelitis, also known as chronic fatigue syndrome (ME/CFS). But there is some overlap, which is what neurology resident Caroline Maness, Trotti and colleagues report in the new paper. The authors use the official term SEID (systemic exertion intolerance disease), which was recommended by an Institute of Medicine panel in 2015, but hasn’t really stuck among those in the ME/CFS field.

Some people with IH have disclosed that they were previously diagnosed with ME/CFS. Outside of the sleepy vs tired issue, some people with IH report symptoms shared with ME/CFS, such as impaired circulation in their extremities in response to cold, or dizziness upon standing. Speculatively, this may point to a possible problem with the autonomic nervous system. Trotti and a collaborator at Stanford, Mitchell Miglis, are now examining this issue further.

ME/CFS has had a history of controversy. Despite its devastating impacts, some have viewed it as psychological or somehow unreal, and sufferers have felt neglected or maligned by mainstream medicine. The National Institutes of Health has made efforts to turn that situation around by investing in ME/CFS research, and there has been a surge of attention recently covering ME/CFS (Amy Maxmen items in Nature, Stanford magazine feature, Unrest documentary).

Trotti, Maness and colleagues didn’t set out to dive into ME/CFS – they explicitly label this paper a pilot study, and the results say more about the “hypersomnolent” group of patients they have been seeing for the last several years, rather than the broader ME/CFS population. Read more

Posted on April 16, 2018 by Quinn Eastman in Neuro Leave a comment

An exceptional electrical thrill ride #CNS2018

A recent paper in Neuropsychologia got a lot of attention on Twitter and at the Cognitive Neuroscience Society meeting in Boston over the weekend. It discusses what can happen when the amygdala, a region of the brain known for regulating emotional responses, receives direct electrical stimulation. A thrill ride – but for only one study participant. Two of nine people noticed the electrical stimulation. One individual reported (a video is included in the paper):

“It was, um, it was terrifying, it was just…it was like I was about to get attacked by a dog. Like the moment, like someone unleashes a dog on you, and it’s just like it’s so close…

He also spontaneously reported “this is fun.” He further explained that he could distinguish feelings in his body that would normally be associated with fear recognized and the absence of an actual threat, making the experience “fun”.

But wait, why were Emory neuroscientists Cory Inman, Jon Willie and Stephan Hamann and colleagues doing this? Read more

Posted on March 29, 2018 by Quinn Eastman in Neuro Leave a comment

Toe in the water for Emory cryo-EM structures

Congratulations to Christine Dunham and colleagues in the Department of Biochemistry for their first cryo-electron microscopy paper, recently published in the journal Structure.

The paper solves the structure of a bacterial ribosome bound to a messenger RNA containing a loop that regulates translation. This process is important for the study of several neurological diseases such as fragile X syndrome, for example.

Christine Dunham, PhD

Dunham writes: “We are focusing on establishing this in bacteria to understand frameshifting and protein folding as a consequence of codon preference. We will then build up our knowledge to potentially study eukaryotic translational control.”

The paper neatly links up with two Nobel Prizes: the 2017 Chemistry prize for cryo-electron microscopy and the 2009 Chemistry prize for ribosome structure, awarded in part to Dunham’s mentor Venki Ramakrishnan. Also, see this 2015 feature from Nature’s Ewen Callaway outlining how cryo-EM is a must have for structural biologists wanting to probe large molecules that are difficult to crystallize.

Construction now underway in the Biochemistry Connector will allow installation of microscopes (worth $6 million) necessary for Dunham and others to do cryo-EM here at Emory, although she advises that it will be several months until they are photo-op ready. For the Structure paper, Dunham collaborated with George Skiniotis at University of Michigan; he recently moved to Stanford. Read more

Posted on March 22, 2018 by Quinn Eastman in Neuro, Uncategorized Leave a comment

Give a zap to Emory brain research for #STATMadness

Next week, we will be asking the Emory research community to support Emory’s entry in a contest. It’s like “Battle of the Bands.” Whoever gets the loudest cheers wins. We have some intriguing neuroscience research. Please help!

STAT Madness is a “March Madness” style bracket competition, but with biomedical research advances as competitors. Universities or research institutes nominate their champions, research that was published the previous year.

Our entry for 2018:

Direct amygdala stimulation can enhance human memory

The findings, from Cory Inman, Jon Willie and colleagues from the Department of Neurosurgery and Joe Manns from Psychology, were the first published example of electrical brain stimulation in humans giving an event-specific boost to memory lasting overnight. The research was conducted with epilepsy patients undergoing an invasive procedure for seizure diagnosis. However, the technology could one day be incorporated into a device aimed at helping those with memory impairments, such as people with traumatic brain injury or neurodegenerative diseases.

Extra note: you may have seen similar neuroscience research in a recent Nature Communications paper, which was described in the New York Times. Cory Inman had some comments below — he and neurosurgeon Robert Gross were co-authors:

The localization to the left lateral temporal cortex was interesting, because it hadn’t been identified as a region that modulates episodic or hippocampus-dependent memory. [The Emory authors stimulated the amygdala.] The more recent paper found a similar size of memory enhancement, with a slightly different and harder memory task of free recall, using “closed-loop” stimulation based on whether the brain is in a ‘bad’ encoding state. It’s possible that closed-loop stimulation could be used with the amygdala as well.

Emory’s first opponoent is University of California, San Francisco. We are about half way down on the right side of the bracket.

As far as voting, you can fill out a whole bracket or you can just vote for Emory, along with other places you may feel an allegiance to. The contest will go several rounds. The first round begins on February 26. If Emory advances, then people will be able to continue voting for us starting March 2.

At the moment, you can sign up to be reminded to vote with an email address at:
https://signup.statnews.com/stat-madness

Starting Monday, February 26, you can follow the 2018 STAT Madness bracket and vote here:
https://www.statnews.com/feature/stat-madness/bracket/

Please share on social media using the hashtag #statmadness2018.

STAT is a life sciences-focused news site, launched in 2015 by the owner of the Boston Globe. It covers medical research and biotech nationally and internationally. Emory took part in 2017’s contest, with Tab Ansari’s groundbreaking work on SIV remission, a collaboration with Tony Fauci’s lab at NIAID.

Posted on February 22, 2018 by Quinn Eastman in Neuro Leave a comment

Viral vectors ready for delivery

The phrase “viral vector” sounds ominous, like something from a movie about spies and internet intrigue. It refers to a practical delivery system for the gene of your choice. If you are a biomedical researcher and you want to tweak genes in a particular part of the body in an experimental animal, viral vectors are the way to go.

Viral vector-transduced retinal ganglion cell; dendrites and axons labeled with GFP. Courtesy Felix Struebling via Xinping Huang

Emory’s Viral Vector Core was started when eminent neuroscientist Kerry Ressler was at Emory and is now overseen by geneticist Peng Jin. Technical director Xinping Huang and her colleagues can produce high-titer viral vectors, lentivirus and AAV. Discuss with her the best choice. It may depend on the size of the genetic payload you want to deliver and whether you want the gene to integrate into the genome of the target cell.

As gene therapy and CRISPR/Cas9-style gene editing research progresses, we can anticipate demand for services such as those provided by the Viral Vector Core. [Clinical applications are close, but will not be dealt with in the same place!] Read more

Posted on February 13, 2018 by Quinn Eastman in Neuro Leave a comment

Sifting proteomes for copper nuggets

Just because scientists know the gene responsible for a rare disease doesn’t mean they know what’s going on. NGLY1 is a good example. A handful of children around the world have an inherited deficiency in NGLY1, leading to a complex neurodevelopmental disorder. A family diagnosed at Emory thought their older affected daughter had cerebral palsy for most of her childhood. How the loss of an enzyme that removes sugar tags from certain proteins causes problems is still being uncovered.

More broadly, geneticists can read a family’s DNA sequences and find the differences, but figuring out what they mean is still a challenge. That’s where the approach taken in a recent paper in Cell Systems, by Emory cell biologist Victor Faundez and colleagues at Illinois State, comes in.

His lab used a comparison of proteomes to dissect Menkes disease, a rare inherited deficiency in a copper transport enzyme called ATP7A. This means they didn’t compare genes; instead, they compared the proteins produced by patients’ cells with those in their unaffected relatives.

Copper is an essential part of the diet and can be found at the active sites of several enzymes. The symptoms of Menkes disease arise because of a lack of copper in the body, although cultured cells lacking ATP7A actually accumulate copper. Read more

Posted on February 2, 2018 by Quinn Eastman in Neuro Leave a comment

Navigating monstrous anticancer obstacles

A new PNAS paper from geneticist Tamara Caspary’s lab identifies a possible drug target in medulloblastoma, the most common pediatric brain tumor. Come aboard to understand the obstacles this research seeks to navigate. Emory library link here.

Standard treatment for children with medulloblastoma consists of surgery in combination with radiation and chemotherapy. Alternatives are needed, because survivors can experience side effects such as neurocognitive impairment. One possibility has emerged in the last decade: inhibitors of the Hedgehog pathway, whose aberrant activation drives growth in medulloblastoma.

Medulloblastoma patients are caught “between Scylla and Charybdis”: facing a deadly disease, the side effects of radiation and/or existing Hedgehog inhibitors. From Wikimedia.

As this 2017 Oncotarget paper from St. Jude’s describes, Hedgehog inhibitors are no fun either. In adults, these agents cause muscle spasms, hair loss, distorted sense of taste, fatigue, and weight loss. In a pediatric clinical trial, the St. Jude group observed growth plate fusions, resulting in short stature. The drug described in the paper was approved in 2012 for basal cell carcinoma, a form of cancer whose growth is also driven by the Hedgehog pathway. Basal cell carcinoma is actually the most common form of human cancer, although it is often caught at an early stage that doesn’t require harsh treatment.

Caspary’s lab studies the Hedgehog pathway in early embryonic development. In the PNAS paper, former graduate student Sarah Bay and postdoc Alyssa Long show that targeting a downstream part of the Hedgehog pathway may be a way to avoid problems presented by both radiation/chemo and existing Hedgehog inhibitors. Read more

Posted on January 30, 2018 by Quinn Eastman in Cancer, Neuro Leave a comment

Epilepsy pick up sticks

Imagine the game of pick up sticks. It’s hard to extract one stick from the pile without moving others. The same problem exists, in a much more complex way, in the brain. Pulling on one gene or neurotransmitter often nudges a lot of others.

Andrew Escayg, PhD

That’s why a recent paper from Andrew Escayg’s lab is so interesting. He studies genes involved in epilepsy. Several years ago, he showed that mice with mutations in the SCN8A gene have absence epilepsy, while also showing resistance to induced seizures. SCN8A is one of those sticks that touches many others. The gene encodes a voltage-gated sodium channel, involved in setting the thresholds for and triggering neurons’ action potentials. Mutating the gene in mice modifies sleep and even enhances spatial memory.

Escayg’s new paper, with first author Jennifer Wong, looks at the effect of “knocking down” SCN8A in the hippocampus in a mouse model of mesial temporal lobe epilepsy. This model doesn’t involve sodium channel genes; it’s generated by injection of a toxin (kainic acid) into the brain. The finding suggests that inhibiting SCN8A may be applicable to other forms of epilepsy. Escayg notes that mesial temporal lobe epilepsy is one of the most common forms of treatment-resistant epilepsy in adults.

Knocking down SCN8A in the hippocampus 24 hours after injection could prevent the development of seizures in 90 percent of the treated mice. “It is likely that selective reduction in Scn8a expression would have directly decreased neuronal excitability,” the authors write. It did not lead to increased anxiety levels or impaired learning/memory.

Currently, no available drugs target Scn8a specifically. However, antisense approaches for neurodegenerative diseases have been gaining ground – perhaps epilepsy could fit in.

Posted on January 25, 2018 by Quinn Eastman in Neuro Leave a comment

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