Neuroscience

A new type of prophylactic treatment for brain injury following prolonged epileptic seizures has been developed by Emory University School of Medicine investigators.

Status epilepticus, a persistent seizure lasting longer than 30 minutes [check this, some people say FIVE], is potentially life-threatening and leads to around 55,000 deaths each year in the United States. It can be caused by stroke, brain tumor or infection as well as inadequate control of epilepsy. Physicians or paramedics now treat status epilepticus by administering an anticonvulsant or general anesthesia, which stops the seizures.

Researchers at Emory have been looking for something different: anti-inflammatory compounds that can be administered after acute status epilepticus has ended to reduce damage to the brain. They have discovered a potential lead compound that can reduce mortality when given to mice after drug-induced seizures.

The results are scheduled for publication Monday in Proceedings of the National Academy of Sciences Early Edition.

"For adults who experience a period of status epilepticus longer than one hour, more than 30 percent die within four weeks of the event, making this a major medical problem," says Ray Dingledine, PhD, chair of the Department of Pharmacology at Emory University School of Medicine. "Medications that would reduce the severe consequences of refractory status epilepticus have been elusive. We believe we have an effective route to minimizing the brain injury caused by uncontrolled status epilepticus."

Dingledine’s laboratory has identified compounds that block the effects of prostaglandin E2, a hormone involved in processes such as fever, childbirth, digestion and blood pressure regulation. Prostaglandin E2 is also involved in the toxic inflammation in the brain arising after status epilepticus.

The first author of the paper is postdoctoral fellow Jianxiong Jiang, PhD, and the medicinal chemist largely responsible for developing the compounds is Thota Ganesh, PhD.

Jiang and colleagues induced status epilepticus in mice with the alkaloid drug pilocarpine, and gave them a compound, TG6-10-1, starting four hours later and again at 21 and 30 hours. TG6-10-1 blocks signals from EP2, one of four receptors for prostaglandin E2.

Among animals that received the EP2 blocker, 90 percent survived after one week, while 60 percent of a control group survived. The scientists also used nest-building behavior and weight loss as gauges of damage to the brain. Four days after status epilepticus, all the animals that received TG6-10-1 displayed normal nest-building, but more than a quarter of living control animals were not able to build nests. In addition, the brains of TG6-10-1-treated mice had reduced levels of inflammatory messenger proteins called cytokines, less brain injury and less breach of the blood-brain-barrier.

Consequences of refractory status epilepticus can include brain damage, difficulty breathing, abnormal heart rhythms and heart failure.

Dingledine says the first clinical test of an EP2 blocking compound would probably be as an add-on treatment for prolonged status epilepticus, several hours after seizures have ended. It could also be tested in similar situations such as subarachnoid hemorrhage, prolonged febrile seizures or medication-resistant epilepsy, he says.

Dingledine and his colleagues have a patent pending for novel technology related to this research. Under Emory policies, they are eligible to receive a portion of any royalties or fees received by Emory from this technology.

Vascular brain injury from conditions such as high blood pressure and stroke are greater risk factors for cognitive impairment among non-demented older people than is the deposition of the amyloid plaques in the brain that long have been implicated in conditions such as Alzheimer’s disease, a study by researchers at the Alzheimer’s Disease Research Center at UC Davis has found.

Published online early today in JAMA Neurology (formerly Archives of Neurology), the study found that vascular brain injury had by far the greatest influence across a range of cognitive domains, including higher-level thinking and the forgetfulness of mild cognitive decline.

The researchers also sought to determine whether there was a correlation between vascular brain injury and the deposition of beta amyloid (Αβ) plaques, thought to be an early and important marker of Alzheimer’s disease, said Bruce Reed, associate director of the UC Davis Alzheimer’s Disease Research Center in Martinez, Calif. They also sought to decipher what effect each has on memory and executive functioning.

“We looked at two questions,” said Reed, professor in the Department of Neurology at UC Davis. “The first question was whether those two pathologies correlate to each other, and the simple answer is ‘no.’ Earlier research, conducted in animals, has suggested that having a stroke causes more beta amyloid deposition in the brain. If that were the case, people who had more vascular brain injury should have higher levels of beta amyloid. We found no evidence to support that.”

"The second,” Reed continued, “was whether higher levels of cerebrovascular disease or amyloid plaques have a greater impact on cognitive function in older, non-demented adults. Half of the study participants had abnormal levels of beta amyloid and half vascular brain injury, or infarcts. It was really very clear that the amyloid had very little effect, but the vascular brain injury had distinctly negative effects.” 

“The more vascular brain injury the participants had, the worse their memory and the worse their executive function – their ability to organize and problem solve,” Reed said.

The research was conducted in 61 male and female study participants who ranged in age from 65 to 90 years old, with an average age of 78. Thirty of the participants were clinically “normal,” 24 were cognitively impaired and seven were diagnosed with dementia, based on cognitive testing. The participants had been recruited from Northern California between 2007 to 2012.

The study participants underwent magnetic resonance imaging (MRI) ― to measure vascular brain injury ― and positron emission tomography (PET) scans to measure beta amyloid deposition: markers of the two most common pathologies that affect the aging brain. Vascular brain injury appears as brain infarcts and “white matter hyperintensities” in MRI scans, areas of the brain that appear bright white.

The study found that both memory and executive function correlated negatively with brain infarcts, especially infarcts in cortical and sub-cortical gray matter. Although infarcts were common in this group, the infarcts varied greatly in size and location, and many had been clinically silent. The level of amyloid in the brain did not correlate with either changes in memory or executive function, and there was no evidence that amyloid interacted with infarcts to impair thinking.

Reed said the study is important because there’s an enormous amount of interest in detecting Alzheimer’s disease at its earliest point, before an individual exhibits clinical symptoms. It’s possible to conduct a brain scan and detect beta amyloid in the brain, and that is a very new development, he said.

“The use of this diagnostic tool will become reasonably widely available within the next couple of years, so doctors will be able to detect whether an older person has abnormal levels of beta amyloid in the brain. So it’s very important to understand the meaning of a finding of beta amyloid deposition,” Reed said.

“What this study says is that doctors should think about this in a little more complicated way. They should not forget about cerebrovascular disease, which is also very common in this age group and could also cause cognitive problems. Even if a person has amyloid plaques, those plaques may not be the cause of their mild cognitive symptoms.”

Genes linked to autism and schizophrenia are only switched on during the early stages of brain development, according to a collaboration between researchers at Imperial College London, the University of Oxford and King’s College London.

This new study adds to the evidence that autism and schizophrenia are neurodevelopmental disorders, a term describing conditions that originate during early brain development.

The researchers studied gene expression in the brains of mice throughout their development, from 15-day old embryos to adults, and their results are published in Proceedings of the National Academy of Sciences.

The research focused on cells in the ‘subplate’, a region of the brain where the first neurons (nerve cells) develop. Subplate neurons are essential to brain development, and provide the earliest connections within the brain.

'The subplate provides the scaffolding required for a brain to grow, so is important to consider when studying brain development,' says Professor Zoltán Molnár, senior author of the paper from the University of Oxford, 'Looking at the pyramids in Egypt today doesn't tell us how they were actually built. Studying adult brains is like looking at the pyramids today, but by studying the developing brains we are able to see the transient scaffolding that has been used to construct it.'

The study shows that certain genes linked to autism and schizophrenia are only active in the subplate during specific stages of development. The data analysis was designed by Dr Enrico Petretto, Senior Lecturer in Genomic Medicine at Imperial College London. Dr Petretto said: “We looked at the full network of genes in the brain to identify which pathways play a role in early brain development. This allowed us to find coherent clusters of genes previously associated with susceptibility to autism spectrum disorders or schizophrenia. These results provide a unique resource for our understanding of how gene behaviour changes in the mouse subplate from the early embryonic stage to adulthood. This means we are better equipped to investigate how the gene network changes in the developing brain and identify any links with neurodevelopmental disorders.”

The team was able to map gene activity in full detail thanks to these new methods which allowed them to dissect and profile gene expression from small numbers of cells. This also enabled them to identify the different populations of subplate neurons more accurately.

Professor Hugh Perry, chair of the Medical Research Council’s Neuroscience and Mental Health Board, said: “By being able to pinpoint common genetic factors for neurological conditions such as autism and schizophrenia, scientists are able to understand an important part of the story as to why things go awry as our brains develop.  The Medical Research Council’s commitment to a broad portfolio of neuroscience and mental health research places us in a unique position to respond to the challenge of mental ill health and its relationship with physical health and wellbeing.”

A discovery using stem cells from a patient with motor neurone disease could help research into treatments for the condition.

The study used a patient’s skin cells to create motor neurons - nerve cells that control muscle activity - and the cells that support them called astrocytes.

Astrocyte death

Researchers studied these two types of cells in the laboratory. They found that a protein expressed by abnormalities in a gene linked to motor neurone disease, which is called TDP-43, caused the astrocytes to die.

The study, led by the University of Edinburgh and funded by the Motor Neurone Disease Association, provides fresh insight into the mechanisms involved in the disease.

Gene mutation

Although TDP-43 mutations are a rare cause of motor neurone disease (MND), scientists are especially interested in the gene because in the vast majority of MND patients, TDP-43 protein (made by the TDP-43 gene) forms pathological clumps inside motor neurons.

Motor neurones die in MND leading to paralysis and early death.

This study shows for the first time that abnormal TDP-43 protein causes death of astrocytes.

The researchers, however, found that the damaged astrocytes were not directly toxic to motor neurons.

Motor neurone disease is a devastating and ultimately fatal condition, for which there is no cure or effective treatment. -Professor Siddharthan Chandran (Director of the Euan Macdonald Centre for Motor Neurone Disease Research)

Implications

Better understanding the role of astrocytes could help to inform research into treatments for motor neurone disease (MND).

These findings, published in the journal Proceedings of the National Academy of Sciences, are significant as they show that different mechanisms are at work in different types of MND.

It is not just a question of looking solely at motor neurons, but also the cells that surround them, to understand why motor neurones die. Our aim is to find ways to slow down progression of this devastating disease and ultimately develop a cure. -Professor Siddharthan Chandran (Director of the Euan Macdonald Centre for Motor Neurone Disease Research)

Hearing impairment is the most common sensory disorder, with congenital hearing impairment present in approximately 1 in 1,000 newborns, and yet there is no physiological cure for children who are born deaf. Most cases of congenital deafness are due to a mutation in a gene that is required for normal development of the sensory hair cells in the inner ear that are responsible for detecting sound. To cure deafness caused by such mutations, the expression of the gene must be corrected, a feat that has been elusive until recently.

Rosalind Franklin University of Medicine and Science (RFUMS) Assistant Professor Michelle Hastings and her team, along with investigators at Louisiana State University Health Sciences Center in New Orleans, Louisiana and Isis Pharmaceuticals in Carlsbad, CA, have now found a way to target gene expression in the ear and rescue hearing and balance in mice that have a mutation that causes deafness in humans. The results of the study are reported in the paper, Rescue of hearing and vestibular function in a mouse model of human deafness, which was published February 4, 2013 in the journal Nature Medicine.

Dr. Hastings collaborated with research leaders across the country, including RFUMS colleagues Francine Jodelka and Anthony Hinrich, who were co-first authors on the study, as well as Dr. Dominik Duelli and Kate McCaffrey; co-first author Dr. Jennifer Lentz at Louisiana State University Health Sciences Center New Orleans, and Dr. Lentz’s research team, including Drs. Hamilton Farris and Nicolas Bazan and Matthew Spalitta; and Dr. Frank Rigo at Isis Pharmaceuticals. The collaboration led to the development of a novel therapeutic approach to treat deafness and balance impairment by injecting mice with a single dose of a small, synthetic RNA-like molecule, called an antisense oligonucleotide (ASO). The ASO was designed to specifically recognize and fix a mutation in a gene called USH1C, that causes Usher syndrome in humans. The ASO blocks the effect of the mutation, allowing the gene product to function properly, thereby preventing deafness.

Usher syndrome is the leading genetic cause of combined deafness and blindness in humans. Treatment of these Usher mice with the ASO early in life rescues hearing and cures all balance problems. “The effectiveness of the ASO is striking,” states Hastings. “A single dose of the drug to newborn mice corrects balance problems and allows these otherwise deaf mice to hear at levels similar to non-Usher mice for a large portion of their life,” she says.

Validating ASO efficacy in the Usher mice is an important step in the process of developing the strategy for human therapy. Dr. Lentz, who has been studying Usher syndrome for almost 10 years and engineered the mice to model the human disease, states, “Successfully treating a human genetic disease in this animal model brings the possibility of treating patients much closer.”

The results of the study demonstrate the therapeutic potential of this type of ASO in the treatment of deafness and provide evidence that congenital deafness can be effectively overcome by treatment early in development to correct gene expression.

"The discovery of an ASO-type drug that can effectively rescue hearing opens the door to developing similar approaches to target and cure other causes of hearing loss," says Dr. Hastings who has been awarded a grant from the National Institute of Health to further develop the ASOs for the treatment of deafness with Drs. Lentz, Rigo and Duelli.

A study out today in the journal Cell Stem Cell shows that human brain cells created by reprogramming skin cells are highly effective in treating myelin disorders, a family of diseases that includes multiple sclerosis and rare childhood disorders called pediatric leukodystrophies.

The study is the first successful attempt to employ human induced pluripotent stem cells (hiPSC) to produce a population of cells that are critical to neural signaling in the brain. In this instance, the researchers utilized cells crafted from human skin and transplanted them into animal models of myelin disease.

"This study strongly supports the utility of hiPSCs as a feasible and effective source of cells to treat myelin disorders," said University of Rochester Medical Center (URMC) neurologist Steven Goldman, M.D., Ph.D., lead author of the study. "In fact, it appears that cells derived from this source are at least as effective as those created using embryonic or tissue-specific stem cells."

The discovery opens the door to potential new treatments using hiPSC-derived cells for a range of neurological diseases characterized by the loss of a specific cell population in the central nervous system called myelin. Like the insulation found on electrical wires, myelin is a fatty tissue that ensheathes the connections between nerve cells and ensures the crisp transmission of signals from one cell to another. When myelin tissue is damaged, communication between cells can be disrupted or even lost.

The most common myelin disorder is multiple sclerosis, a condition in which the body’s own immune system attacks and destroys myelin. The loss of myelin is also the hallmark of a family of serious and often fatal diseases known as pediatric leukodystrophies. While individually very rare, collectively several thousand children are born in the U.S. with some form of leukodystrophy every year.

The source of the myelin cells in the brain and spinal cord is cell type called the oligodendrocyte. Oligodendrocytes are, in turn, the offspring of another cell called the oligodendrocyte progenitor cell, or OPC. Myelin disorders have long been considered a potential target for cell-based therapies. Scientists have theorized that if healthy OPCs could be successfully transplanted into the diseased or injured brain, then these cells might be able to produce new oligodendrocytes capable of restoring lost myelin, thereby reversing the damage caused by these diseases.

However, several obstacles have thwarted scientists. One of the key challenges is that OPCs are a mature cell in the central nervous system and appear late in development.

"Compared to neurons, which are among the first cells formed in human development, there are more stages and many more steps required to create glial cells such as OPCs," said Goldman. "This process requires that we understand the basic biology and the normal development of these cells and then reproduce this precise sequence in the lab."

Another challenge has been identifying the ideal source of these cells. Much of the research in the field has focused on cells derived from tissue-specific and embryonic stem cells. While research using these cells has yielded critical insight into the biology of stem cells, these sources are not considered ideal to meet demand once stem cell-based therapies become more common.

The discovery in 2007 that human skin cells could be “reprogrammed” to the point where they returned to a biological state equivalent of an embryonic stem cell, called induced pluripotent stem cells, represented a new path forward for scientists. Because these cells – created by using the recipient’s own skin – would be a genetic match, the likelihood of rejection upon transplantation is significantly diminished. These cells also promised an abundant source of material from which to fashion the cells necessary for therapies.

Goldman’s team was the first to successfully master the complex process of using hiPSCs to create OPCs. This process proved time consuming. It took Goldman’s lab four years to establish the exact chemical signaling required to reprogram, produce, and ultimately purify OPCs in sufficient quantities for transplantation and each preparation required almost six months to go from skin cell to a transplantable population of myelin-producing cells.

Once they succeeded in identifying and purifying OPCs from hiPSCs, they then assessed the ability of the cells to make new myelin when transplanted into mice with a hereditary leukodystrophy that rendered them genetically incapable of producing myelin.

They found that the OPCs spread throughout the brain and began to produce myelin. They observed that hiPSC-derived cells did this even more quickly, efficiently, and effectively than cells created using tissue-derived OPCs. The animals were also free of any tumors, a dangerous potential side effect of some stem cell therapies, and survived significantly longer than untreated mice.

"The new population of OPCs and oligodendrocytes was dense, abundant, and complete," said Goldman. "In fact, the re-myelination process appeared more rapid and efficient than with other cell sources."

The next stage in evaluating these cells – clinical studies – may not be long in the offing. Goldman, along with a team of researchers and clinicians from Rochester, Syracuse, and Buffalo, are preparing to launch a clinical trial using OPCs to treat multiple sclerosis. This group, titled the Upstate MS Consortium, has been approved for funding by New York State Stem Cell Science (NYSTEM). While the consortia’s initial study – the early stages of which are scheduled to begin in 2015 – will focus cells derived from tissue sources, Goldman anticipates that hiPSC-derived OPCs will eventually be included in this project.

Driving through his hometown, a war veteran with post-traumatic stress disorder may see roadside debris and feel afraid, believing it to be a bomb. He’s ignoring his safe, familiar surroundings and only focusing on the debris; yet, when it comes to the visual cortex, a recent study at the University of Florida suggests this is completely normal.

The findings, published last month in the Journal of Neuroscience, show that even people who don’t have anxiety disorders respond visually at the sight of something scary while ignoring signs that indicate safety. This contradicts a common belief that only people with anxiety disorders have difficulty processing comforting visual stimuli, or safety cues, said Andreas Keil, a professor of psychology in UF’s College of Liberal Arts and Sciences.

“We’ve established that, in terms of visual responding, it’s not a disorder to not respond to a safety cue,” Keil said. “We all do that. So now we can study at what stage in the processing stream, with given patients, is the problem occurring.”

Co-authors Keil and Vladimir Miskovic, both members of the UF Center for the Study of Emotion and Attention, examined the effect of competing danger and safety cues within the visual cortex. The study results could help distinguish between normal and abnormal processes within the visual cortex and identify what parts of the brain are targets for the treatment of anxiety disorders.

“You’d think the visual cortex would just faithfully code for visual information,” said Shmuel Lissek, an assistant professor of psychology at the University of Minnesota not involved in the study. “This kind of work is testing the idea that activations in the visual cortex are actually different if the stimulus has an emotional value than if it doesn’t.”

Injury to the subcortical structures of the inner brain is a major contributor to worsening neurological abnormalities after “awake craniotomy” for brain tumors, reports a study in the February issue of Neurosurgery, official journal of the Congress of Neurological Surgeons. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.

During a procedure intended to protect critical functional areas in the outer brain (cortex), damage to subcortical areas—which may be detectable on MRI scans—is a major risk factor for persistent neurological deficits. “Our ability to identify and preserve cortical areas of function can still result in significant neurological decline postoperatively as a result of subcortical injury,” write Dr. Victoria T. Trinh and colleagues of The University of Texas MD Anderson Cancer Center, Houston.

Risk Factors for Neurological Deficits after Awake Craniotomy

The researchers analyzed factors associated with worsening neurological function after awake craniotomy for brain tumor surgery. In awake craniotomy, the patient is sedated but conscious so as to be able to communicate with the surgeon during the operation.

The patient is asked to perform visual and verbal tasks while specific areas of the cortex are stimulated, generating a functional map of the brain surface. This helps the surgeon navigate safely to the tumor without damaging the “eloquent cortex”—critical areas of the brain involved in language or movement.

The study included 241 patients who underwent awake craniotomy with functional brain mapping from 2005 through 2010. Of these, 40 patients developed new neurological abnormalities. Dr. Trinh and colleagues examined potential predictive factors—including changes on a type of MRI scan called diffusion-weighted imaging (DWI).

Of the 40 cases with new neurological deficits, 36 developed while the surgeon was operating in the subcortical areas of the brain. These are the inner structures of the brain, located beneath the outer, folded brain cortex. Just one abnormality developed while the surgeon was operating in the cortex only.

MRI Changes May Reflect Subcortical Damage

Neurological abnormalities developing while the surgeon was operating in the subcortex were likely to remain after surgery, and to persist at three months’ follow-up evaluation. Dr. Trinh and coauthors write, “Patients with intraoperative deficits during subcortical dissection were over six times more likely to have persistently worsened neurological function at three-month follow-up.”

In these patients, MRI scans showing more severe changes in the DWI pattern in the subcortex also predicted lasting neurological abnormalities. Of patients who had neurological deficits immediately after surgery and significant DWI changes, 69 percent had persistent deficits three months after surgery.

Patients who had “positive” cortical mapping—that is, in whom eloquent cortex was located during functional mapping—were somewhat more likely to have neurological abnormalities immediately after surgery. However, the risk of lasting abnormalities was not significantly higher compared to patients with negative cortical mapping.

Awake craniotomy with brain stimulation produces a “real-time functional map” of the brain surface that is invaluable to the neurosurgeon in deciding how best to approach the tumor. The new results suggest that, even when the eloquent cortex is not located on cortical mapping, subcortical areas near the tumor can still be injured during surgery. “Subcortical injury is the primary cause of neurological deficits following awake craniotomy procedures,” Dr. Trinh and colleagues write.

The researchers add, “Preserving subcortical areas during tumor resections may reduce the severity of both immediate and late neurological sequelae.” Based on their findings, they believe subcortical mapping techniques may play an important role in avoiding complications after awake craniotomy.