Tuesday, March 1, 2011

Survival of the Sickest--Book Review

Survival of the Sickest (A Medical Maverick Discovers Why We Need Disease)

By Dr. Sharon Moalem with Jonathan Prince

This book was referred to me by a cousin who is an RN and works in an ICU. It sounded a little bit interesting, but it honestly took an empty afternoon in total isolation without other books available before I picked this one up. However, after 30 minutes of reading, I was hooked. The authors have masterfully told the story of hemachromatosis, epigenetics, toxoplasma gondii, and the Hayflick limit (and that’s just the beginning) and woven them all into the story of the human family. I honestly enjoyed the stories, and my understanding of the body was exponentially expanded. Here are some highlights:

“Remember how natural selection works. If a given genetic trait makes you stronger—especially if it makes you stronger before you have children—then you’re more likely to survive, reproduce, and pass that trait on. If a given trait makes you weaker, you’re less likely to survive, reproduce, and pass that trait on.”

“Cholesterol is required to make and maintain cell membranes. It helps the brain to send messages and the immune system to protect us against cancer and other diseases. It’s a key building block in the production of estrogen and testosterone and other hormones. And it is the essential component in our manufacture of vitamin D through a chemical process that is similar to photosynthesis in its dependence on the sun. Fortunately, the body is so efficient at making vitamin D that, as long as people get sufficient sun exposure and have enough cholesterol, we can usually accumulate enough vitamin D reserves to get us through the darker months. By the way, the next time you get your cholesterol checked, make a note of the season. Because sunlight converts cholesterol to vitamin D, cholesterol levels can be higher in winter months.”

Dr. Moalem also tells of an Australian campaign to encourage sunscreen usage. He concludes, “The campaign was especially effective at producing unintended results—Australian sun exposure went down, and Australian vitamin D deficiencies went up.”

“As everybody knows, skin color changes, to some extent, in response to sun exposure. The trigger for that response is the pituitary gland. Under natural circumstances, almost as soon as you are exposed to the sun, your pituitary gland produces hormones that act as boosters for your melanocytes, and your melanocytes start producing melanin on overdrive. Unfortunately, it’s very easy to disrupt that process. The pituitary gland gets its information from the optic nerve—when the optic nerve senses sunlight, it signals the pituitary gland to kick-start the melanocytes. Guess what happens when you’re wearing sunglasses? Much less sunlight reaches the optic nerve, much less warning is sent to the pituitary gland, much less melanocyte-stimulating hormone is released, much less melanin is produced—and much more sunburn results. If you’re reading this book on the beach with you Ray-Bans on, do your skin a favor—take them off.”

“Less than 3 percent of your DNA contains instructions for building cells. The vast majority of your DNA—97 percent of it—isn’t active in building anything. Think about that. If you took the DNA from any cell in your body and laid it end to end, it would reach the top of Shaquille O’Neal’s head—but the DNA that actively codes for building your body wouldn’t even reach his ankle.” Dr. Moalem goes on to explain what this DNA does and where it is believed to come from, which was FASCINATING. Hint: integration of bacteria and viruses within our own DNA.

“It’s clear that genes don’t have discrete jobs at all—there wouldn’t be nearly enough genes to produce all the proteins necessary for human life if each gene only had one job. Instead, single genes have the capacity to produce many, many different proteins through a complex process of copying, cutting, and combining instructions. In fact, like a casino dealer who never stops, genes can shuffle and reshuffle endlessly to produce a huge array of proteins. . . . Instead of imagining genes as a set of discrete instructions, scientists have begun to conceive of them as an intricate network of information, with an overall regulatory structure that can lead to change.”

Dr. Moalem also described the work of Barbara McClintock. Dr. McClintock discovered, using plants, that in certain circumstances, the environment triggered large changes in the genome.She discovered whole sequences of DNA moving from one place to another, even inserting themselves into active genes. When these genes cut and pasted themselves from one place in the corn’s DNA to another, they actually affected nearby genes, by changing the sequence of the DNA, they sometimes turned genes on and sometimes turned them off. What’s more, McClintock found that these wandering genes weren’t behaving completely randomly—there was a method to their meandering. First of all, they relocated to certain parts of the genome more often than to other parts. Second, these active mutations appeared triggered by outside influences, by changes in the environment that threatened the survival of the corn, like extreme heat or drought. In short, the corn plant seemed to be engaged in some sort of intentional mutation—neither random, nor rare. Today, the genetic nomads McClintock discovered are called “jumping genes,” and they have reshaped our understanding of mutation and evolution.Over the next thirty years, as biology and genetics evolved, jumping genes were found in other genomes, beyond corn. Our understanding of mutation began to shift.

“Scientists are still only beginning to understand how jumping genes—or transposons, as they’re known—actually work. Sometimes they copy and paste—copying themselves and then inserting the new materials elsewhere in the genome while remaining in their original location.Other times they cut and paste—removing themselves from their starting place and inserting themselves somewhere else. Sometimes the new genetic element stays in place, and sometimes it’s removed by the proofreading system or suppressed by other methods. This much is clear—sometimes these transposable genetic elements remain in an active gene once they’ve inserted themselves, and they make a difference.”

“Jumping genes are very active in the early stages of brain development, inserting genetic material all over the developing brain, almost helter skelter, as a normal part of brain development. Every time one of those jumpers inserts or changes genetic material in brain cells, it’s technically a mutation. And all of that genetic jumping around may have a very important purpose—it may help to create the variety and individuality that make every brain unique. This developmental frenzy of genetic copy and paste only happened in the brain, because that’s where we benefit from individuality. But as the lead author of the study that discovered the phenomenon, Professor Fred Gage said, “You wouldn’t want that added element of individuality in your heart.” You knew brain development had to be in here somewhere. Ha!ha! This understanding of brain development really gives me a new appreciation of the uniqueness of every person. Dr. Moalem later teaches that with the most complex mathematical equations known, they haven’t been able to find a combination of the jumping genes that would produce an exact replica—no two of us are alike, and aren’t likely to be. This also made me think of all the environmental issues we introduce to children while those jumping genes are doing their job—poor nutrition, pollutants, vaccines, etc.

Because of the complicated and detailed nature of the subject, I cannot begin to do justice to “Survival of the Sickest” with (relatively) short excerpts. I would highly recommend reading this book. I was able to find this book in my local public library—and loved it so much that I paid a fine for keeping it too long. LOL!