Myths about locked-in syndrome

Here’s a cheerful, if unanticipated bit of news: most patients suffering from locked-in syndrome (LIS) feel that they lead happy lives. Steven Laureys and his colleagues from the University Hospital of Liège, Vrije Universiteit Brussel and the French Association for LIS surveyed a group of LIS patients and got some surprising results.

LIS occurs when a person is completely paralyzed by a brain stem injury. The person is completely conscious and aware of his surroundings, but unable to move or communicate other than by eye movements (in extreme cases, the person cannot blink, but those patients were not part of this study). One might think such patients would feel that their lives were bleak and hopeless, and even that they might prefer euthanasia. One would be wrong.

It turns out that in a group of 91 LIS patients who completed the survey, 72% said they were happy. Only 7% said they would opt for euthanasia if they could. Of the people who were unhappy, many had sustained their brain injury relatively recently. The data suggest that patients require a long adjustment period and may be encouraged to know that in time they will probably feel better about themselves and about their lives.

One major caveat to this study is the fact that there were only 91 completed surveys out of an initial cohort of 168 LIS patients. If every one of the remaining 77 people were too miserable to respond to a survey, that drops the happy group down to just under 40%. But hey, I’ll take it! If that many people can be happy while living with LIS, I think it says some very positive things about human nature.

Planet caught in formation

Planets are formed when the swirling dust and gas that circles young stars coalesces into solid bodies. For the first time, astronomers have found what they believe is a planet in the process of formation.

The star T Chamaeleontis (T Cha) is a very young star (seven million years old) located about 350 light years from Earth. Like many young stars, it is surrounded by a ring of dust. However, astronomers led by Johan Olofsson of the Max Planck Institute were able to discern a gap in that disk. They used an instrument called the Very Large Telescope (VLT) Interferometer to observe that the star was encircled by dust at a distance of about 20 million kilometers, and again at about 1.1 billion kilometers. The space between those two rings was largely devoid of dust.

There are a number of mechanisms that can account for the dissipation of dust around a star, including planet formation. Nuria Huélamo of Centro de Astrobiología and a team of astronomers used another instrument on the VLT to find such a planet. The candidate object was located about a billion kilometers from T Cha, near the outer edge of the dust gap. The scientists aren’t sure yet whether the object will turn out to be a brown dwarf surrounded by dust or a planet.

In any case, this is the first example of an object in the process of clearing a path around a star by accreting all the dust and gas within that region.

Caption: This artist’s impression shows the disc around the young star T Cha. Using ESO’s Very Large Telescope this disc has been found to be in two parts, a narrow ring close to the star and the remainder of the disc material much further out. A companion object, seen in the foreground, has been detected in the gap in the disc that may be either a brown dwarf or a large planet. The inner dust disc is lost in the glare of the star on this picture.

Credit: ESO/L. Calçada

A new way to study aging

Researchers from the Salk Institute are using induced pluripotent stem cells (IPS cells) to study aging. The cells were induced from patients suffering from Hutchinson-Gilford Progeria Syndrome, an extremely rare (1 in 8 million) genetic disorder that causes premature aging.

This is a 4-year-old boy with Hutchinson-Gilford Progeria Syndrome.

Photo: Courtesy of The Progeria Research Foundation

Normal human aging is difficult to study because the lifespan of the average researcher is the same as that of the average patient. No one scientist could follow a group of people from birth to old age. Unless, that is, the people are unfortunate enough to suffer from Progeria, in which case they exhibit the symptoms of accelerated aging and are unlikely to live past the age of 13. Progeria is caused by a single base pair change (point mutation) in the lamin A gene, which results in a defect in their cells' nuclear structure.

The Salk researchers, led by Juan Carlos Izpisúa Belmonte, used cells from Progeria patients to create IPS cells. Since lamin A is not expressed in embryonic stem cells, the transformed IPS cells lacked the hallmarks of the disease. They appeared completely normal and acted like healthy cells. However, when these Progeria IPS cells were allowed to differentiate into smooth muscle cells, the symptoms of Progeria reappeared.

When the Progeria IPS cells were first genetically modified to prevent the expression of lamin A and then allowed to differentiate, the resultant muscle cells did not show signs of premature aging. This means that the researchers could not only use Progeria cells to watch the aging process unfold more rapidly, but they could also control whether or not the cells experienced rapid aging. Besides being a model for normal aging, the Salk scientists hope this study will lead to a potential treatment for Progeria.

Reoviruses vs. cancer

Today, cancer is being fought in many ways, including using viruses. For example, reoviruses, RNA viruses that can cause mild gastrointestinal illness, are known to kill cancer cells. Alan Melcher from the University of Leeds and his colleagues have found that the secreted products of reovirus infections can kill cancer cells even in the absence of the virus itself.

When reoviruses infect a cell, they induce that cell to secrete chemicals that both cause its own death and initiate the body’s immune response against that cell. Normal cells can protect themselves from this onslaught by secreting their own protective protein called PKR. However, many types of cancer cells inactivate PKR, leaving them vulnerable to reovirus attack.

In this study, the researchers took the growth media from dying reovirus-infected human melanoma cells and administered that extract to new tumor cells. Even in the absence of live virus, immune cells were recruited to attack the cancer cells.

Although this line of attack is only in the preliminary stages, I wonder if eventually doctors will be able to brew up great vats of cancer-fighting reovirus media.

Monitoring Killer Mice from Space

When I found the above title, I thought I'd be reading about a plague of deadly space mice and our efforts to keep track of them. No such luck. The story is actually about linking the satellite imagery of plant growth with the risk of contracting rodent-borne illness. After getting over my initial disappointment, I realized that the real study was interesting in its own right.

Denise Dearing and her colleagues from the University of Utah used the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA's Terra satellite to generate satellite images of the plant life in Utah. Between 2003 and 2006, changes in vegetation were measured. Over an overlapping period of nine years, the researchers conducted twice yearly (spring and fall) trappings of deer mice, determining both the total number of mice and the percentage infected with hantavirus, a deadly pathogen. Hantavirus is acquired by breathing in the dried urine or feces of infected deer mice, and kills about half the people who contract it.

The scientists found that the amount of vegetation visible in the satellite images correlated very well with the total number of deer mice in an area. As the percentage of hantavirus-infected mice did not vary, more total mice meant proportionately more infected mice. Thus, the scientists were able to predict when people would be most at risk for encountering the disease.

The researchers suggest that this method could be used to create risk maps for other rodent-borne diseases. That would be pretty cool, but maybe not as cool as killer mice from space. Oh well.

Just for fun: NASA image of the day

Did you know that NASA posts an 'Image of the Day' on their website? This recent example is a view of Venus.

This composite image of Venus was processed to improve contrast and to emphasize small features, and was color-coded to represent elevation. Images were from the Magellan and Venera spacecraft and the Earth-based Arecibo radar observatory.

Image Credit: NASA/JPL/USGS

The strange life of neurons

Research by Mark Sheffield, a graduate student of Nelson Spruston (Northwestern University), changes a lot of what we thought we knew about neurons. Among other hitherto unknown properties, neurons can send signals from the axon back to the cell body.

A typical nerve cell has a cell body or ‘soma’ surrounded by dendrites, and an axon that, in humans, can be more than a meter long. Signals are received by the dendrites, passed through the soma and then through the axon, from whence they are transmitted to the next cell’s dendrites. Signals are propagated by extremely fast changes in the ion content of the cells. Special pores along the cell membrane called ‘voltage-gated ion channels’ let specific ions in or out at a prodigious speed, creating an electric impulse that travels through the cell. Each gate is open for milliseconds or less as the signal is passed forward.

That pattern still holds true, but Sheffield and his colleagues have found that this isn’t the only story. In some cases, signals can go back up the line from the axon to the soma. This is actually an amazing finding, given that the ion channels were thought to open and then shut in only one direction along the length of the axon.

Even stranger, the researchers found that axons could fire even when no signal originated from either the dendrites or the soma. And finally, what surprised the scientists the most was that one axon could stimulate another axon without having sent a signal through either dendrites or soma.

The signals sent either back to the soma or straight to another axon were thousands of times slower than the typical axon-dendrite-soma-axon signal processing. The researchers suggest that nerve cells may be using these different types of signal conduction for different purposes.