Two items relevant to long COVID

One of the tricky issues in studying in long COVID is: how widely do researchers cast their net? Initial reports acknowledged that people who were hospitalized and in intensive care may take a while to get back on their feet. But the number of people who had SARS-CoV-2 infections and were NOT hospitalized, yet experienced lingering symptoms, may be greater. A recent report from the United Kingdom, published in PLOS Medicine, studied more than Read more

All your environmental chemicals belong in the exposome

Emory team wanted to develop a standard low-volume approach that would avoid multiple processing steps, which can lead to loss of material, variable recovery, and the potential for Read more

Signature of success for an HIV vaccine?

Efforts to produce a vaccine against HIV/AIDS have been sustained for more than a decade by a single, modest success: the RV144 clinical trial in Thailand, whose results were reported in 2009. Now Emory, Harvard and Case Western Reserve scientists have identified a gene activity signature that may explain why the vaccine regimen in the RV144 study was protective in some individuals, while other HIV vaccine studies were not successful. The researchers think that this signature, Read more

Department of Neurology

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 by Quinn Eastman in Neuro Leave a comment

The journey of a marathon sleeper

A marathon sleeper who got away left some clues for Emory and University of Florida scientists to follow. What they found could provide benefits for patients with the genetic disease myotonic dystrophy (DM) and possibly the sleep disorder idiopathic hypersomnia (IH).

The classic symptom for DM is: someone has trouble releasing their grip on a doorknob. However, the disease does not only affect the muscles. Clinicians have recognized for years that DM can result in disabling daytime sleepiness and sometimes cognitive impairments. At the Myotonic Dystrophy Foundation meeting in September, a session was held gathering patient input on central nervous system (CNS) symptoms, so that future clinical trials could track those symptoms more rigorously.

Emory scientists are investigating this aspect of DM. Cell biology chair Gary Bassell was interested in the disease, because it’s a triplet repeat disorder, similar to fragile X syndrome, yet the CNS mechanisms and symptoms are very different. In DM, an expanded triplet or quadruplet repeat produces toxic RNA, which disrupts the process of RNA splicing, affecting multiple cell types and tissues.

Rye at San Francisco myotonic dystrophy meeting. Photo courtesy of Hypersomnia Foundation.

Neurologist and sleep specialist David Rye also has become involved. Recall Rye’s 2012 paper in Science Translational Medicine, which described a still-mysterious GABA-enhancing substance present in the spinal fluid of some super-sleepy patients. (GABA is a neurotransmitter important for regulating sleep.)

In seven of those patients, his team tested the “wake up” effects of flumazenil, conventionally used as an antidote to benzodiazepines. One of those patients was an Atlanta lawyer, whose recovery was later featured in the Wall Street Journal and on the Today Show. It turns out that another one of the seven, whose alertness increased in response to flumazenil, has DM.

In an overnight sleep exam, this man slept for 12 hours straight – the longest of the seven. But an IH diagnosis didn’t fit, because in the standard “take a nap five times” test, he didn’t doze off very quickly. He became frustrated with the stimulants he was given and sought treatment elsewhere, Rye says. Lab Land doesn’t have all the details of this patient’s history, but eventually he was diagnosed with DM, which clarified his situation. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Imaging sleep drunkenness: #IHAW2017

At some point, everyone has experienced a temporary groggy feeling after waking up called sleep inertia. Scientists know a lot about sleep inertia already, including how it impairs cognitive and motor abilities, and how it varies with the time of day and type of sleep that precedes it. They even have pictures of how the brain wakes up piece by piece.

People with idiopathic hypersomnia or IH display something that seems stronger, termed “sleep drunkenness,” which can last for hours. Czech neurologist Bedrich Roth, the first to identify IH as something separate from other sleep disorders, proposed sleep drunkenness as IH’s defining characteristic.

Note: Emory readers may recall the young Atlanta lawyer treated for IH by David Rye, Kathy Parker and colleagues several years ago. Our post today is part of IH Awareness Week® 2017.

Sleep drunkenness is what makes IH distinctive in comparison to narcolepsy, especially narcolepsy with cataplexy, whose sufferers tend to fall asleep quickly. Those with full body cataplexy can collapse on the floor in response to emotions such as surprise or amusement. In contrast, people with IH tend not to doze off so suddenly, but they do identify with the statement “Waking up is the hardest thing I do all day.”

At Emory, neurologist Lynn Marie Trotti and colleagues are in the middle of a brain imaging study looking at sleep drunkenness.

“We want to find out if sleep drunkenness in IH is the same as what happens to healthy people with sleep inertia and is more pronounced, or whether it’s something different,” Trotti says. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Granulins treasure not trash – potential FTD treatment strategy

Emory University School of Medicine researchers have developed tools that enable them to detect small proteins called granulins for the first time inside cells. Granulins are of interest to neuroscientists because mutations in the granulin gene cause frontotemporal dementia (FTD). However, the functions of granulins were previously unclear.

FTD is an incurable neurodegenerative disease and the most common type of dementia in people younger than 60. Genetic variants in the granulin gene are also a risk factor for Alzheimer’s disease and Parkinson’s disease, suggesting this discovery may have therapeutic potential for a broad spectrum of age-related neurodegenerative diseases.

The results were published August 9 by the journal eNeuro (open access).

Thomas Kukar, PhD

Some neuroscientists believed that granulins were made outside cells, and even could be toxic under certain conditions. But with the newly identified tools, the Emory researchers can now see granulins inside cells within lysosomes, which are critical garbage disposal and recycling centers. The researchers now propose that granulins have important jobs in the lysosome that are necessary to maintain brain health, suppress neuroinflammation, and prevent neurodegeneration.

Problems with lysosomes appear in several neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

“A lysosomal function for granulins is exciting and novel.  We believe it may provide an explanation why decreased levels of granulins are linked to multiple neurodegenerative diseases, ranging from frontotemporal dementia to Alzheimer’s,” says senior author Thomas Kukar, PhD, assistant professor of pharmacology and neurology and the Emory University Center for Neurodegenerative Disease. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Mitochondrial blindness — Newman’s Emory story

Neuro-ophthalmologist Nancy Newman’s 2017 Dean’s Distinguished Faculty Lecture and Award were unexpectedly timely. Her talk on Tuesday was a tour of her career and mitochondrial disorders affecting vision, culminating in a description of gene therapy clinical trials for the treatment of Leber’s hereditary optic neuropathy.

The sponsor of those studies, Gensight Biologics, recently presented preliminary data on a previous study of their gene therapy at the American Academy of Neurology meeting in April. Two larger trials (REVERSE and RESCUE) are ongoing.

Despite all the progress, there are still several puzzles connected with mitochondrial diseases affecting vision and particularly Leber’s, the first human disease linked to mitochondrial DNA mutations by Douglas Wallace at Emory in the 1980s.

Newman called Leber’s an “ideal laboratory” for studying mitochondrial diseases of vision, because deterioration of vision in Leber’s tends to happen to one eye first, presenting a window of opportunity to deliver treatment to the other eye. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Enhanced verbal abilities in the congenitally blind

A recent paper in Experimental Brain Research from Emory neuroscientist Krish Sathian and colleagues demonstrates that congenitally blind study participants displayed superior verbal, but not spatial abilities, when compared to their sighted counterparts. This may reflect both greater reliance on verbal information, and the recruitment of the visual cortex for verbal tasks.

Sathian’s team has also been investigating, through brain imaging studies, whether the visual cortex is involved in the processing of metaphors (2016 SFN abstract) in the congenitally blind. They previously showed that blind study participants were better at identifying rotated objects by touch. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

How “twist my arm” engages the brain

Listening to metaphors involving arms or legs loops in a region of the brain responsible for visual perception of those body parts, scientists have discovered.

The finding, recently published in Brain & Language, is another example of how neuroscience studies are providing evidence for “grounded cognition” – the idea that comprehension of abstract concepts in the brain is built upon concrete experiences, a proposal whose history extends back millennia to Aristotle.

The EBA was shown in 2001 to respond selectively to images of the human body by Nancy Kanwisher and colleagues.

When study participants heard sentences that included phrases such as “shoulder responsibility,” “foot the bill” or “twist my arm”, they tended to engage a region of the brain called the left extrastriate body area or EBA.

The same level of activation was not seen when participants heard literal sentences containing phrases with a similar meaning, such as “take responsibility” or “pay the bill.”  The study included 12 right-handed, English-speaking people, and blood flow in their brains was monitored by functional MRI (magnetic resonance imaging).

“The EBA is part of the extrastriate visual cortex, and it was known to be involved in identifying body parts,” says senior author Krish Sathian, MD, PhD, professor of neurology, rehabilitation medicine, and psychology at Emory University.  “We found that the metaphor selectivity of the EBA matches its visual selectivity.” Read more

Posted on by Quinn Eastman in Neuro Leave a comment

Sensory connections spill over in synesthesia

Neuroscientists at Emory University have found that people who experience a mixing of the senses, known as synesthesia, are more sensitive to associations everyone has between the sounds of words and visual shapes. The results are published in the European Journal of Neuroscience.

Synesthesia is a stable trait, and estimated to be present in 1 to 4 percent of people. It can be inherited, although the precise genes have not been identified. One of the most common forms of synesthesia is when people involuntarily see particular colors in connection with letters, numbers or sounds.

Many artists and composers have described their experiences with synesthesia. Children with synesthesia say sometimes that it is distracting when they are trying to read. Thus, understanding the origins of synesthesia may help people with dyslexia or other learning differences, or people who have lost their sight or hearing and are trying to engage in sensory substitution for rehabilitation.

Researchers led by neurologist Krish Sathian, MD, PhD, recruited 17 people with synesthesia, and asked them to take a form of the IAT (implicit association test). Known for its use probing social attitudes such as racial prejudice, the IAT can also assess “cross-modal correspondences.”

An example of a cross-modal correspondence is that we describe musical notes as being “high” or “low” – words that also signify relative positions in space. Another is that we think of some sounds such as “m” and “l” as soft, and are more likely to associate them with rounded shapes. Similarly, we connect hard sounds such as “k” and “t” with angular shapes.

“There’s been a debate about synesthesia,” Sathian says. “Are the associations synesthetes have just extreme versions of cross-modal correspondences that other people have, or are they qualitatively different?”

Sathian and his colleagues found that people with synesthesia were more sensitive to correspondences between the sounds of pseudowords — words without meaning in English — and rounded or angular shapes. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

The secrets of a new Alzheimer’s secretase

The title of Keqiang Ye’s recent Nature Communications paper contains a provocative name for an enzyme: delta-secretase.

Just from its name, one can tell that a secretase is involved in secreting something. In this case, that something is beta-amyloid, the toxic protein fragment that tends to accumulate in the brains of people with Alzheimer’s disease.

Aficionados of Alzheimer’s research may be familiar with other secretases. Gamma-secretase was the target of some once-promising drugs that failed in clinical trials, partly because they also inhibit Notch signaling, important for development and differentiation in several tissues. Now beta-secretase inhibitors are entering Alzheimer’s clinical trials, with similar concerns about side effects.

Many Alzheimer’s researchers have studied gamma- and beta-secretases, but a review of the literature reveals that so far, only Ye and his colleagues have used the term delta-secretase.

This enzyme previously was called AEP, for asparagine endopeptidase. AEP appears to increase activity in the brain with aging and cleaves APP (amyloid precursor protein) in a way that makes it easier for the real bad guy, beta-secretase, to produce bad beta-amyloid.*At Alzforum, Jessica Shugart describes the enzyme this way:

Like a doting mother, AEP cuts APP into bite-sized portions for toddler BACE1 [beta-secretase] to chew on, facilitating an increase in beta-amyloid production. Read more

Posted on by Quinn Eastman in Neuro Leave a comment

The buzz of consciousness and how seizures disrupt it

These days, it sounds a bit old-fashioned to ask the question: “Where is consciousness located in the brain?” The prevailing thinking is that consciousness lives in the network, rather than in one particular place. Still, neuroscientists sometimes get an intriguing glimpse of a critical link in the network.

A recent paper in the journal Epilepsy & Behavior describes an epilepsy patient who had electrodes implanted within her brain at Emory University Hospital, because neurologists wanted to understand where her seizures were coming from and plan possible surgery. Medication had not controlled her seizures and previous surgery elsewhere had not either.

ElectrodesSmaller

MRI showing electrode placement. Yellow outline indicates the location of the caudate and thalamus. Image from Leeman-Markowsi et al, Epilepsy & Behavior (2015).

During intracranial EEG monitoring, implanted electrodes detected a pattern of signals coming from one part of the thalamus, a central region of the brain. The pattern was present when the patient was conscious, and then stopped as soon as seizure activity made her lose awareness.

The pattern of signals had a characteristic frequency – around 35 times per second – so it helps to think of the signal as an auditory tone. Lead author Beth Leeman-Markowski, director of EUH’s Epilepsy Monitoring Unit at the time when the patient was evaluated, describes the signal as a “buzz.”

“That buzz has something to do with maintenance of consciousness,” she says. Read more

Posted on by Quinn Eastman in Neuro Leave a comment