|
04/01/2016
Challenging Projects in Astronomy and Medicine
CHAPTER 67 Anticipating a Telescope and a Future Without Opioids
Last month I was torn between writing about parrots or about gravitational waves and ended up writing about both. This month I had planned to write about NASA's most complex and expensive project to date, the James Webb Space Telescope, but became intrigued by a number of articles dealing with one of nature's most complex achievements, the human brain. Once again, I'll try writing about both subjects.
First the JWST. We've all seen the breathtaking pictures of our universe taken by the Hubble Space Telescope. You may remember the disappointing early days after its launch, when it was realized that the Hubble's main mirror/lens was not properly ground. It was as though millions of dollars had been spent placing in orbit an optical device with the wrong prescription. Thankfully, we had the space shuttle and our intrepid astronauts managed to attach corrective optics to the Hubble, which orbits at an altitude low enough (currently in the neighborhood of 330 miles above the Earth's surface) that we could use the shuttle to accomplish the mission. Not so with the James Webb, which will orbit about 930,000 miles from Earth, not to mention we don't have the shuttle anymore!
The James Webb is roughly an $8 billion dollar investment, NASA's most expensive project to date. It will be a hundred times more sensitive than the Hubble but that's not the only difference between the two telescopes. The main reason for the James Webb is the quest to see even farther back into the earliest days of our universe than can the Hubble. The problem in looking back to the earliest days of our universe lies in the following - as the light from those earliest days travels to us billions of light years away, the universe has been expanding. Those light waves, or photons, are stretched out as the universe expands. By the time they arrive here, their wavelengths are stretched from the visible into the longer wavelength infrared region of the spectrum. This is a region invisible to us humans but the James Webb will be designed with detectors that can "see" farther into the infrared spectrum than the Hubble. Hence, the James Webb holds out the possibility that we can see things happening much closer to the big bang than we've seen with the Hubble.
I had not realized the complexity of the James Webb until I read an article titled "The Next Big Eye" by Daniel Clery in the February 19 issue of Science. I won't go into the troubled history of the project but, after reading about the complexity of the telescope, I will be pleasantly surprised if it is launched on schedule in October of 2018. Over a thousand people in 17 different countries have been working on the James Webb for over two decades. I was surprised to learn that the telescope will be making quite a journey before its launch. It's too large to fit in a plane and will be making a trip on a ship from California down through the Panama Canal to French Guiana, where the telescope will be launched on an Ariane 5 rocket from the European Space Agency's spaceport there. I was also surprised to find that the primary mirror is not glass, but consists of 18 hexagons made of beryllium metal coated with gold! The diameter of the main mirror is a bit over 21 feet, while the sunshield is the size of a tennis court. The sunshield is a crucial component of the telescope, which has to be extremely cold to detect those weak infrared signals, which would be swamped by the heat of the sun.
Given the size and shape of the James Webb, it has to be folded up into a compact enough package to fit in the rocket assembly used in the launch. I cannot imagine the stress that the James Webb team will experience during the launch and the hopefully successful unfolding of that package when it reaches its orbit. If I'm still alive I'll certainly look forward to whatever the telescope reveals about the earliest days of our universe.
Billions of years after those earliest days, our solar system evolved and here on Earth a brain came into existence. Determining the time when the first brain appeared had not been thought possible, given the fact that the soft matter making up a brain was not deemed likely to leave any traces in fossils dating back hundreds of millions of years. However, an article by Elizabeth Pennisi in the November 13, 2015 issue of Science cites recent work that dates the first appearance of a brain back to some 520 million years ago, roughly 300 million years earlier than the ages of previous fossils containing evidence of a brain. Back in 2008, Chinese paleontologists found traces of a central nervous system in a 520-million-year-old shrimplike fossil. Later, Chinese paleontologist Xiaoya Ma showed one of the specimens to University of Arizona neuroscientist Nicholas Strausfeld, a recipient of a Macarthur Foundation "genius" award. Strausfeld recognized that these traces were actually a complete three-part brain and he and Ma published a paper in Nature in 2012. The paper was met with skepticism but, more recently, Strausfeld, Ma and Gregory Edgecombe, a paleontologist at the Natural History Museum in London have published a paper on seven more of those shrimplike fossils showing brains preserved in the form of carbon or iron filings.
Well, now that we know there were brains around a half billion years ago, how did our own human brain evolve into the powerful organism that it is today? I've seen papers over the years speculating on various scenarios such as the need for a bigger, more complex brain to deal with the move of our human ancestors out of the trees onto the plains and a walking environment. One theory was that toolmaking was a key factor in the development of the human brain. This possibility is the subject of an interesting article by Dietrich Stout titled "Tales of a Stone Age Neuroscientist" in the April 2016 issue of Scientific American. Stout, a professor of anthropology at Emory University, with his fellow researchers and students, has been involved in a program to develop the skills needed to chip away at stones to make stone tools of a quality achieved by our human ancestors 500,000 years ago. More specifically, the program involves using modern brain imaging techniques to monitor changes in the brain as the toolmakers learn their craft and improve their skills in knapping stones to make axes.
Knapping a piece of stone to form a hand ax isn't something achieved easily. The researchers found that typically some 300 hours or so were required to achieve a level of skill equivalent to that of our non-homo sapiens ancestors 500,000 years ago. The main goal of the project was to see if there was indeed any measurable effect of acquiring knapping skills on the brain. Specifically, the researchers wanted to know if the toolmaking can cause in an individual the same kind of anatomical changes as has occurred over the course of human evolution.
As Stout puts it, "The answer turns out to be a resounding yes..." The researchers looked at the brains of the knappers making their axes using MRI, PET (positron emission tomography) and something I had not heard of before, DTI (diffusion tensor imaging, a form of MRI that reveals the mapping of the white matter fiber in the brain). This white matter fiber serves as the brain's "wiring". Sure enough, it turned out that the subjects' white matter in certain regions was enhanced, more as the subjects continued practicing their knapping. The amount of change was predictable depending on the number of hours spent knapping. The conclusion is that toolmaking could indeed have been a driver of evolution of the human brain.
In a recent magazine section of a Sunday New York Times, there was an article titled "Sixth Sense" by Kim Tingley that dealt with how sailors in the Marshall Islands have managed to sail over thousands of miles of open pecan and end up at their destinations without the benefit of any instruments. The long article was fascinating in describing modern attempts to repeat those instrument-free journeys using something called wave-navigation. The article discusses the general problem of how humans and other animals have orientation skills. One example cited is one that I discussed in a column some time ago, the use of the Milky Way by dung beetles to find their way back home with their dung. But what caught my attention was when the article cited a study by neuroscientist Eleanor Maguire on cab drivers in London. If you've been to London, you will know that driving in London is not for the faint of heart. For a cabbie to find his or her way from point A to point B requires a knowledge of an exceedingly complex layout of roadways.
Maguire found that as the London taxi drivers learned the complex map of the city parts of their hippocampus region of the brain increased in size as they continued to become more and more familiar with the city map so to speak. Sounds quite a bit like the finding about knapping stone tools affecting the structure of the brain, doesn't it? What got me was that, when the cabbies retired, those parts of the hippocampus that had gotten larger shrank in size. Maguire's study was done in the late 1990s. Now fast forward to the world of today and Siri and the GPS. McGill University neuroscientist Veronique Bohbot has found that driving around using GPS to tell us where to go doesn't activate the hippocampus at all, raising the question as to whether we might be missing something crucial by relying on technology to guide us around in our environment.
On a completely different tack, the brain is involved in one of today's most serious problems, resulting in tens of thousands of deaths every year. The problem is opioids, or opioid-based painkillers such as morphine, codeine, oxycodone and hydrocodone. These drugs act by attaching to opioid receptors in the brain. I'm reasonably sure that I benefitted from such drugs in the past couple of decades when I had a kidney cancer operation in which a rib was removed along with part of a kidney and also a hip replacement operation. In both cases, I was amazed that I had no pain of any consequence. Thankfully, I did not follow the route that too many people have followed after hospital stays or bouts of a painful malady, namely continuing to take these powerful drugs, which gradually lose their effectiveness and the patient takes more and more of the drug, becoming addicted.
In an article in the April 2016 issue of Discover magazine, Leah Shaffer discusses the search for alternatives to the opioids, alternatives that work, not in the brain, but by blocking pain signals before they can reach the brain. What is a pain signal? It's the body trying to tell you something's wrong, there's damage to some of your cells. A damaged cell leaks out a sodium ion charge through a pore in the cell membrane known as sodium channel 1.7. This bit of sodium ion leakage amplifies the pain signal so it registers in the brain. Hey, what if you could somehow block this channel 1.7 so the sodium ion didn't leak out? No pain signal, no pain, no opioid needed? Back in 2006, UK geneticist Geoffrey Woods published an account of a trip he took to Pakistan, where he heard about a fellow who performed in a street show, stabbing himself in the arm without any pain. After getting patched up in the hospital, he would be back on the street, repeating his performance. This led Woods to the discovery of two families who carried a genetic mutation that -you guessed it - blocked the action of channel 1.7!
Today, the hunt is on for drugs that block channel 1.7 but there are problems. One problem is that many of the most promising candidates are compounds found is such critters as scorpions, spiders, tarantulas , centipedes, snails, etc. Just getting enough of the venom from these small animals to allow screening tests is a problem. For thousands of years the Chinese have used scorpion venom to relieve pain and other maladies. The venom has been found to be a sodium channel blocker. Another problem is that there are at least nine other types of sodium channels that have different functions in the body. A potential pain killing drug has to be selective only for the 1.7 channel. If the drug should also block sodium channel 1.5, for example, the patient would die of heart failure! Hopefully, in a few years a compound will be found in sufficient quantities to carry out the necessary tests to establish safety and effectiveness in blocking channel 1.7. If so, I would hope talented chemists will then be able to synthesize the drug and put the opioids out of business, saving thousands of lives lost to drug addiction.
Next column, hopefully, on or about May 1. Hopefully, by that time the polar vortex will no longer be a topic of conversation and old Bortrum will have again resumed his quest to shoot par on our local par-3 golf course. OK, realistically, Bortrum will be happy any time he shoots 35 or under on the par 27 course.
Allen F. Bortrum
|
