Anyone who watches TV, reads magazines, or flips through catalogs has seen some interesting products. Maybe they seem plausible to you, maybe they don’t. However, a little investigation shows they are based less on science and well…actually working, and more on wishful thinking. At worst they’re actual con-jobs, designed to separate you from your money as efficiently as possible (which I guess is a certain standard of success).
As a result, we at Double X Science are starting a new series: “As Seen on TV!” In these features, we’ll look at some of the products shilled on talk shows and infomercials, items lurking between the articles you read in magazines, or things you might find on the shelves of the stores where you shop.
Our first entry is one I spotted in SkyMall, the catalog you (if you’re like me) read if you forget to bring a book on an airplane. Where else can you find dog water bowls shaped like toilets or sports chairs built deliberately too large for anyone, so you look tiny sitting in them? While the catalog is full of impractical items (to put it mildly), some of them go beyond that into the realm of…imagination. Yeah, I’ll call it that. It avoids potential lawsuits.
It’s the Aging Accelerator! With Magnets!
Here’s the idea: depending on which device you buy, you insert either a glass or a bottle of wine, and within 10 seconds! it ages the wine, with the unspoken assumption that this is desirable. (It also evidently works for whiskey, but I’ll skip that discussion in the current article.) Now, anything that promises to drastically alter something within 10 seconds! is probably suspicious to begin with, but that’s the part I’m going to leave alone. After all, magnets do work quickly, so if the device does what it claims to do, it’s quite possible that 10 seconds will be enough time for the magic to happen.
Well, it seems like magic to me. I went to a winery last weekend, and spoke to one of the vintners there (yup, that’s the name for ‘em). She told me that not all wines should be aged, and the reason has to do both with the way wine is made and how it is stored.
First, not all wine should be aged! All wines actually go bad over time, including many of the usual types you may see in the store. That time may be pretty long, but you don’t want to just buy any bottle, stick it in your basement, and wait 20 years to drink it – most of them won’t taste good. According to my source, the days are gone where you might buy bottles of wine and put them in a cellar for your children. (Who has a wine cellar now anyway? I live in a second-floor apartment!) Basically, my source tells me to ask an expert if you have any doubts, but basically all wine is sold today in a drinkable state – no aging is necessary or even wanted. (I can’t endorse it, but Wikipedia has a list of wines that can be aged, and possible ranges.) Earth’s magnetic field has nothing to do with the aging process, whatever the ad says.
Second, the reason some wines age better than others has to do with their chemistry: how much sugar is in the grapes and how much tannin content they have. Red wines typically are higher in tannins because the skins are thrown in with the flesh of the fruit – and tannins act as a preservative. Sugar also acts as a preservative, but it’s not as effective, so white wines (lower in tannins, higher in sugar) don’t keep as well.
The point I’m trying to make is that wine aging isn’t mysterious, either why it happens or how. I don’t have the “Aging Accelerator” package in front of me, so I can’t tell you if they give advice on which wines to put in it and which ones to avoid, but the picture shows both reds and whites. So let’s turn to the way the device is supposed to work: magnetism.
They certainly have one thing right: neodymium magnets are very strong! (Neodymium is one of the “rare earth” elements, found near the bottom of the periodic table, so sometimes you’ll see them referred to as “rare earth magnets”.) When I’ve used neodymium magnets for various experiments, two of them attracting each other pinched my fingers hard enough to create blood blisters.
Admittedly magnets can seem mysterious: understanding exactly how they work requires looking at electrons and atoms, which might seem a little out of the ordinary. However, challenging isn’t the same thing as magical, but some people seem to think that magnets are capable of all sorts of feats, from curing arthritis to – yes – aging wine.
How magnets actually work could be the topic of an “Everyday Science” post, but in brief: the way a material responds to a magnet is called its magnetic susceptibility. Some materials, like neodymium, are very susceptible, but most things aren’t, including the human body. (Some organisms such as pigeons use Earth’s magnetic field to navigate, but exactly how they do it is still not known.) I couldn’t find any particular data on the magnetic susceptibility of tannins or other molecules in wine, but my feeling is it’s not large. Tannins are big biological molecules – think DNA or proteins – and those don’t tend to be magnetic.
But here’s the deal: suppose tannins are magnetic. Why then would exposing them to a magnetic field age the wine? Simply putting a strong magnet near your wine would merely rearrange the molecules inside the liquid – it’s like stirring it, in other words. Obviously stirring something can change the way it tastes, since it can mix sediments in, but that’s not the same thing as aging.
So, let’s wrap up: why should we be suspicious of paying $60 or $100 for an “Aging Accelerator”?
The concept misuses a well-understood physical principle – magnetism. Just because someone doesn’t understand how it works doesn’t mean it can perform miracles.
The aging process is chemical, and we understand how that works – it involves tannins, sugars, and other molecules. There are no secrets, in other words, and nothing simple to make your wine taste better.
Basically, if it sounds like a magic trick, it probably is – but its main result will be to magic money out of your pocket.
We’ll see these kinds of rules repeated throughout the series!
Stay tuned for further installments of “As Seen on TV!”
Anyone who watches TV, reads magazines, or flips through catalogs has seen some interesting products. Maybe they seem plausible to you, maybe they don’t. However, a little investigation shows they are based less on science and well…actually working, and more on wishful thinking. At worst they’re actual con-jobs, designed to separate you from your money as efficiently as possible (which I guess is a certain standard of success). As a result, we at Double X Science bring you “As Seen on TV!” In these features, we’ll look at some of the products shilled on talk shows and infomercials, items lurking between the articles you read in magazines, or things you might find on the shelves of the stores where you shop.
I admit it, I’m a balding dude. My forehead is gradually taking over my entire scalp, replacing my formerly thick and curly hair with a vast expanse of pink skin. Yes, dear readers: My hair was once so thick and curly that, when I wore it long and in a ponytail, ladies would ask me for my secret. (The answer: Wash it every other day with some brand of cheap shampoo and let it air dry. Don’t tell.) I don’t like the fact of my impending baldness, so I’m sympathetic toward defoliation-sufferers who want to bring their hair back at any cost.
On the other hand, I don’t think I’ll invest in any of the hair restoration products advertised in the SkyMall catalog I picked up on my flight to my brother’s wedding in San Francisco. I counted seven products in this single catalog promising to restore hair in one way or another, either reversing baldness or filling in thin patches on the scalp –- and that doesn’t include hair-coloring, extensions, or other options. I won’t cover all of them, but no fewer than three products pledge to bring hair back through the magic of lasers.
Ah, lasers. They may not have the mystique of magnets or the nous of “natural”, but they are a frequent ingredient in modern snake oil. (Come to think of it, one of the hair-restoration products may have contained snake oil. I don’t want to ask.) But while lasers can help correct nearsightedness in some cases, perform minimally invasive surgeries, and remove hair, color my scalp skeptical about their ability to restore hair.
First, a disclaimer: I’m not a biologist, a doctor, medical researcher, or in any field related to those. I’m a physicist, so the closest I ever get professionally to this topic is the “no-hair” theorem in black hole physics. The “no-hair” theorem says that black holes have very few distinguishing characteristics: only mass and rotational rate (and technically electric charge as well, though it’s hard to build up enough charge to make a difference). The analogy is that, if all humans were completely hairless, we would have a lot fewer ways to tell each other apart. In other words, this ain’t my area, so bear (bare) with me!
Night on Baldhead Mountain
Hair loss can occur for a wide variety of reasons: chemotherapy, a number of unrelated diseases, even stress. However, as humans (both men and women!) age, we all tend to lose our hair to some degree. The effect is most pronounced in male pattern baldness (a bare patch on the top of the head merging over time with the growing forehead to leave a fringe around the edges of the scalp) or female pattern baldness (a general loss of hair at the top of the scalp). However, past the age of 80, nearly everyone starts losing hair, regardless of genetics, diet, or health.
The reasons, as with so many other things, are hormonal. Hair production is governed by sex hormones: most famously testosterone, but also a less well-known cousin known as dihydrotestosterone (DHT). In some people, DHT commands the follicles — the small organs in the skin that produce and feed hair — to shrink, producing ever-finer hair until they cease operating entirely. Thus, gradual hair loss of the usual (as opposed to disease- or circumstance-derived) variety is generally preceded by the hair itself becoming thinner and fuzzier.
My naive understanding of the biology of hair loss leads me to suspect that since hormones are the culprit behind hair loss, then any hair restoration should address those hormones in some way. That alone makes me suspicious of the laser-based products SkyMall peddles. To see why, let’s look at lasers themselves.
Lasers (without sharks)
The word “laser” began as an acronym: Light Amplification by the Stimulated Emission of Radiation. The details could be an Everyday Science or Double Xplainer post in their own right, but here’s the short version. The lasers used in the SkyMall products are LED lasers, meaning they are based on the underlying physics as LED lights. An electric current kicks electrons or other electric charge carriers from one type of material to another across a junction. The excess energy the electric charge sheds during this process is given off in the form of a photon, a particle of light. Since the same amount of energy is involved every time, light from LEDs is nearly monochromatic, meaning it is almost purely one color.
The “amplification” part of the name comes by putting the LED into a special kind of cavity with reflective walls. These walls set up standing waves for the light, which interfere constructively like vibrations in a guitar string, making them brighter. However, unlike guitar strings, the production of the light in lasers is a self-feeding process, resulting in the different parts of the system synchronizing until they emit photons in concert with each other. It’s really interesting stuff, and while it’s somewhat complicated, there’s nothing really mysterious or magical about it, any more than magnets are magical.
In fact, LED lasers are so unmagical that you can buy them as cat toys. LED lasers are the inner workings of laser pointers, which you can buy very inexpensively at any number of shops.
The smell of frying follicles
One of three laser-based hair-restoration products from SkyMall. This one features built-in headphones, so you can at least listen to music while you sit around looking like a fool. However, I recommend a cheaper set of headphones, since the $700 price tag is a bit steep, and you’d get the same result with regards to hair restoration.
Laser hair removal uses intense lasers to selectively heat the follicles in the skin, hopefully avoiding damage to the rest of the skin. This process can slow down hair growth and cause the hair to fall out of the treated follicles, but it doesn’t always actually stop it: the treatment must be continued for a long term. Basically, the laser is damaging the follicle.
As you can imagine, that also makes me skeptical that lasers can stimulate new hair growth. Lasers produce light…and that’s it! In addition to the usual red lasers like in laser pointers, manufacturers also make infrared lasers, which are useful for surgery. While we perceive infrared as heat (which is why sunshine feels warm), I don’t think merely warming the scalp is going to make hair grow faster, or else you wouldn’t need lasers at all — an electric blanket would do just as well. Too much heating and we’re back at laser hair removal.
Similarly, visible-light lasers like the kind that seem to be in these SkyMall products simply produce red light. Because ordinary light bulbs produce a broad range of colors (white light is a mixture of all the visible-light wavelengths), sitting under a desk lamp would expose your scalp to red light. Yes, it wouldn’t be as intense as lasers, but you could do the same trick with a laser pointer from Schtaples (the Scmoffice Schmupply Schtore), provided you have the patience to hold it against your scalp for long periods of time.
The author engages in home laser hair restoration, while his cats meow around his feet.
So, to summarize:
Hair loss in its most common forms is hormonal, so it’s unclear to me that light (whether laser or otherwise) has anything to do with it. Hair removal can be achieved with lasers, but that involves causing damage to hair follicles, not using anything intrinsic to light.
Lasers are simply very monochromatic light sources, that use synchronization of atoms on the microscopic level to do their business. There’s nothing in a laser that isn’t in ordinary light bulbs, though you can make things far more intense with a laser. However, high intensity brings us back to laser hair removal, not restoration.
As always, if a product sounds miraculous, it’s probably bunkum. If all it took to regrow hair was a glorified laser pointer, nobody would be bald! LED lasers are cheap and ubiquitous; we could all restore our hair without paying a company $700 (and listen to the music on inexpensive headphones, to boot).
Now if you’ll pardon me, I’ll get back to shining this laser pointer at my scalp.
The four basic categories of molecules for building life are carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates serve many purposes, from energy to structure to chemical communication, as monomers or polymers.
Lipids, which are hydrophobic, also have different purposes, including energy storage, structure, and signaling.
Proteins, made of amino acids in up to four structural levels, are involved in just about every process of life.
The nucleic acids DNA and RNA consist of four nucleotide building blocks, and each has different purposes.
The longer version
Life is so diverse and unwieldy, it may surprise you to learn that we can break it down into four basic categories of molecules. Possibly even more implausible is the fact that two of these categories of large molecules themselves break down into a surprisingly small number of building blocks. The proteins that make up all of the living things on this planet and ensure their appropriate structure and smooth function consist of only 20 different kinds of building blocks. Nucleic acids, specifically DNA, are even more basic: only four different kinds of molecules provide the materials to build the countless different genetic codes that translate into all the different walking, swimming, crawling, oozing, and/or photosynthesizing organisms that populate the third rock from the Sun.
Big Molecules with Small Building Blocks
The functional groups, assembled into building blocks on backbones of carbon atoms, can be bonded together to yield large molecules that we classify into four basic categories. These molecules, in many different permutations, are the basis for the diversity that we see among living things. They can consist of thousands of atoms, but only a handful of different kinds of atoms form them. It’s like building apartment buildings using a small selection of different materials: bricks, mortar, iron, glass, and wood. Arranged in different ways, these few materials can yield a huge variety of structures.
We encountered functional groups and the SPHONC in Chapter 3. These components form the four categories of molecules of life. These Big Four biological molecules are carbohydrates, lipids, proteins, and nucleic acids. They can have many roles, from giving an organism structure to being involved in one of the millions of processes of living. Let’s meet each category individually and discover the basic roles of each in the structure and function of life.
You have met carbohydrates before, whether you know it or not. We refer to them casually as “sugars,” molecules made of carbon, hydrogen, and oxygen. A sugar molecule has a carbon backbone, usually five or six carbons in the ones we’ll discuss here, but it can be as few as three. Sugar molecules can link together in pairs or in chains or branching “trees,” either for structure or energy storage.
When you look on a nutrition label, you’ll see reference to “sugars.” That term includes carbohydrates that provide energy, which we get from breaking the chemical bonds in a sugar called glucose. The “sugars” on a nutrition label also include those that give structure to a plant, which we call fiber. Both are important nutrients for people.
Sugars serve many purposes. They give crunch to the cell walls of a plant or the exoskeleton of a beetle and chemical energy to the marathon runner. When attached to other molecules, like proteins or fats, they aid in communication between cells. But before we get any further into their uses, let’s talk structure.
The sugars we encounter most in basic biology have their five or six carbons linked together in a ring. There’s no need to dive deep into organic chemistry, but there are a couple of essential things to know to interpret the standard representations of these molecules.
Check out the sugars depicted in the figure. The top-left molecule, glucose, has six carbons, which have been numbered. The sugar to its right is the same glucose, with all but one “C” removed. The other five carbons are still there but are inferred using the conventions of organic chemistry: Anywhere there is a corner, there’s a carbon unless otherwise indicated. It might be a good exercise for you to add in a “C” over each corner so that you gain a good understanding of this convention. You should end up adding in five carbon symbols; the sixth is already given because that is conventionally included when it occurs outside of the ring.
On the left is a glucose with all of its carbons indicated. They’re also numbered, which is important to understand now for information that comes later. On the right is the same molecule, glucose, without the carbons indicated (except for the sixth one). Wherever there is a corner, there is a carbon, unless otherwise indicated (as with the oxygen). On the bottom left is ribose, the sugar found in RNA. The sugar on the bottom right is deoxyribose. Note that at carbon 2 (*), the ribose and deoxyribose differ by a single oxygen.
The lower left sugar in the figure is a ribose. In this depiction, the carbons, except the one outside of the ring, have not been drawn in, and they are not numbered. This is the standard way sugars are presented in texts. Can you tell how many carbons there are in this sugar? Count the corners and don’t forget the one that’s already indicated!
If you said “five,” you are right. Ribose is a pentose (pent = five) and happens to be the sugar present in ribonucleic acid, or RNA. Think to yourself what the sugar might be in deoxyribonucleic acid, or DNA. If you thought, deoxyribose, you’d be right.
The fourth sugar given in the figure is a deoxyribose. In organic chemistry, it’s not enough to know that corners indicate carbons. Each carbon also has a specific number, which becomes important in discussions of nucleic acids. Luckily, we get to keep our carbon counting pretty simple in basic biology. To count carbons, you start with the carbon to the right of the non-carbon corner of the molecule. The deoxyribose or ribose always looks to me like a little cupcake with a cherry on top. The “cherry” is an oxygen. To the right of that oxygen, we start counting carbons, so that corner to the right of the “cherry” is the first carbon. Now, keep counting. Here’s a little test: What is hanging down from carbon 2 of the deoxyribose?
If you said a hydrogen (H), you are right! Now, compare the deoxyribose to the ribose. Do you see the difference in what hangs off of the carbon 2 of each sugar? You’ll see that the carbon 2 of ribose has an –OH, rather than an H. The reason the deoxyribose is called that is because the O on the second carbon of the ribose has been removed, leaving a “deoxyed” ribose. This tiny distinction between the sugars used in DNA and RNA is significant enough in biology that we use it to distinguish the two nucleic acids.
In fact, these subtle differences in sugars mean big differences for many biological molecules. Below, you’ll find a couple of ways that apparently small changes in a sugar molecule can mean big changes in what it does. These little changes make the difference between a delicious sugar cookie and the crunchy exoskeleton of a dung beetle.
Sugar and Fuel
A marathon runner keeps fuel on hand in the form of “carbs,” or sugars. These fuels provide the marathoner’s straining body with the energy it needs to keep the muscles pumping. When we take in sugar like this, it often comes in the form of glucose molecules attached together in a polymer called starch. We are especially equipped to start breaking off individual glucose molecules the minute we start chewing on a starch.
Double X Extra: A monomer is a building block (mono = one) and a polymer is a chain of monomers. With a few dozen monomers or building blocks, we get millions of different polymers. That may sound nutty until you think of the infinity of values that can be built using only the numbers 0 through 9 as building blocks or the intricate programming that is done using only a binary code of zeros and ones in different combinations.
Our bodies then can rapidly take the single molecules, or monomers, into cells and crack open the chemical bonds to transform the energy for use. The bonds of a sugar are packed with chemical energy that we capture to build a different kind of energy-containing molecule that our muscles access easily. Most species rely on this process of capturing energy from sugars and transforming it for specific purposes.
Polysaccharides: Fuel and Form
Plants use the Sun’s energy to make their own glucose, and starch is actually a plant’s way of storing up that sugar. Potatoes, for example, are quite good at packing away tons of glucose molecules and are known to dieticians as a “starchy” vegetable. The glucose molecules in starch are packed fairly closely together. A string of sugar molecules bonded together through dehydration synthesis, as they are in starch, is a polymer called a polysaccharide (poly = many; saccharide = sugar). When the monomers of the polysaccharide are released, as when our bodies break them up, the reaction that releases them is called hydrolysis.
Double X Extra: The specific reaction that hooks one monomer to another in a covalent bond is called dehydration synthesis because in making the bond–synthesizing the larger molecule–a molecule of water is removed (dehydration). The reverse is hydrolysis (hydro = water; lysis = breaking), which breaks the covalent bond by the addition of a molecule of water.
Although plants make their own glucose and animals acquire it by eating the plants, animals can also package away the glucose they eat for later use. Animals, including humans, store glucose in a polysaccharide called glycogen, which is more branched than starch. In us, we build this energy reserve primarily in the liver and access it when our glucose levels drop.
Whether starch or glycogen, the glucose molecules that are stored are bonded together so that all of the molecules are oriented the same way. If you view the sixth carbon of the glucose to be a “carbon flag,” you’ll see in the figure that all of the glucose molecules in starch are oriented with their carbon flags on the upper left.
The orientation of monomers of glucose in polysaccharides can make a big difference in the use of the polymer. The glucoses in the molecule on the top are all oriented “up” and form starch. The glucoses in the molecule on the bottom alternate orientation to form cellulose, which is quite different in its function from starch.
Storing up sugars for fuel and using them as fuel isn’t the end of the uses of sugar. In fact, sugars serve as structural molecules in a huge variety of organisms, including fungi, bacteria, plants, and insects.
The primary structural role of a sugar is as a component of the cell wall, giving the organism support against gravity. In plants, the familiar old glucose molecule serves as one building block of the plant cell wall, but with a catch: The molecules are oriented in an alternating up-down fashion. The resulting structural sugar is called cellulose.
That simple difference in orientation means the difference between a polysaccharide as fuel for us and a polysaccharide as structure. Insects take it step further with the polysaccharide that makes up their exoskeleton, or outer shell. Once again, the building block is glucose, arranged as it is in cellulose, in an alternating conformation. But in insects, each glucose has a little extra added on, a chemical group called an N-acetyl group. This addition of a single functional group alters the use of cellulose and turns it into a structural molecule that gives bugs that special crunchy sound when you accidentally…ahem…step on them.
These variations on the simple theme of a basic carbon-ring-as-building-block occur again and again in biological systems. In addition to serving roles in structure and as fuel, sugars also play a role in function. The attachment of subtly different sugar molecules to a protein or a lipid is one way cells communicate chemically with one another in refined, regulated interactions. It’s as though the cells talk with each other using a specialized, sugar-based vocabulary. Typically, cells display these sugary messages to the outside world, making them available to other cells that can recognize the molecular language.
Lipids: The Fatty Trifecta
Starch makes for good, accessible fuel, something that we immediately attack chemically and break up for quick energy. But fats are energy that we are supposed to bank away for a good long time and break out in times of deprivation. Like sugars, fats serve several purposes, including as a dense source of energy and as a universal structural component of cell membranes everywhere.
Fats: the Good, the Bad, the Neutral
Turn again to a nutrition label, and you’ll see a few references to fats, also known as lipids. (Fats are slightly less confusing that sugars in that they have only two names.) The label may break down fats into categories, including trans fats, saturated fats, unsaturated fats, and cholesterol. You may have learned that trans fats are “bad” and that there is good cholesterol and bad cholesterol, but what does it all mean?
Let’s start with what we mean when we say saturated fat. The question is, saturated with what? There is a specific kind of dietary fat call the triglyceride. As its name implies, it has a structural motif in which something is repeated three times. That something is a chain of carbons and hydrogens, hanging off in triplicate from a head made of glycerol, as the figure shows. Those three carbon-hydrogen chains, or fatty acids, are the “tri” in a triglyceride. Chains like this can be many carbons long.
Double X Extra: We call a fatty acid a fatty acid because it’s got a carboxylic acid attached to a fatty tail. A triglyceride consists of three of these fatty acids attached to a molecule called glycerol. Our dietary fat primarily consists of these triglycerides.
Triglycerides come in several forms. You may recall that carbon can form several different kinds of bonds, including single bonds, as with hydrogen, and double bonds, as with itself. A chain of carbon and hydrogens can have every single available carbon bond taken by a hydrogen in single covalent bond. This scenario of hydrogen saturation yields a saturated fat. The fat is saturated to its fullest with every covalent bond taken by hydrogens single bonded to the carbons.
Saturated fats have predictable characteristics. They lie flat easily and stick to each other, meaning that at room temperature, they form a dense solid. You will realize this if you find a little bit of fat on you to pinch. Does it feel pretty solid? That’s because animal fat is saturated fat. The fat on a steak is also solid at room temperature, and in fact, it takes a pretty high heat to loosen it up enough to become liquid. Animals are not the only organisms that produce saturated fat–avocados and coconuts also are known for their saturated fat content.
The top graphic above depicts a triglyceride with the glycerol, acid, and three hydrocarbon tails. The tails of this saturated fat, with every possible hydrogen space occupied, lie comparatively flat on one another, and this kind of fat is solid at room temperature. The fat on the bottom, however, is unsaturated, with bends or kinks wherever two carbons have double bonded, booting a couple of hydrogens and making this fat unsaturated, or lacking some hydrogens. Because of the space between the bumps, this fat is probably not solid at room temperature, but liquid.
You can probably now guess what an unsaturated fat is–one that has one or more hydrogens missing. Instead of single bonding with hydrogens at every available space, two or more carbons in an unsaturated fat chain will form a double bond with carbon, leaving no space for a hydrogen. Because some carbons in the chain share two pairs of electrons, they physically draw closer to one another than they do in a single bond. This tighter bonding result in a “kink” in the fatty acid chain.
In a fat with these kinks, the three fatty acids don’t lie as densely packed with each other as they do in a saturated fat. The kinks leave spaces between them. Thus, unsaturated fats are less dense than saturated fats and often will be liquid at room temperature. A good example of a liquid unsaturated fat at room temperature is canola oil.
A few decades ago, food scientists discovered that unsaturated fats could be resaturated or hydrogenated to behave more like saturated fats and have a longer shelf life. The process of hydrogenation–adding in hydrogens–yields trans fat. This kind of processed fat is now frowned upon and is being removed from many foods because of its associations with adverse health effects. If you check a food label and it lists among the ingredients “partially hydrogenated” oils, that can mean that the food contains trans fat.
Double X Extra: A triglyceride can have up to three different fatty acids attached to it. Canola oil, for example, consists primarily of oleic acid, linoleic acid, and linolenic acid, all of which are unsaturated fatty acids with 18 carbons in their chains.
Why do we take in fat anyway? Fat is a necessary nutrient for everything from our nervous systems to our circulatory health. It also, under appropriate conditions, is an excellent way to store up densely packaged energy for the times when stores are running low. We really can’t live very well without it.
Phospholipids: An Abundant Fat
You may have heard that oil and water don’t mix, and indeed, it is something you can observe for yourself. Drop a pat of butter–pure saturated fat–into a bowl of water and watch it just sit there. Even if you try mixing it with a spoon, it will just sit there. Now, drop a spoon of salt into the water and stir it a bit. The salt seems to vanish. You’ve just illustrated the difference between a water-fearing (hydrophobic) and a water-loving (hydrophilic) substance.
Generally speaking, compounds that have an unequal sharing of electrons (like ions or anything with a covalent bond between oxygen and hydrogen or nitrogen and hydrogen) will be hydrophilic. The reason is that a charge or an unequal electron sharing gives the molecule polarity that allows it to interact with water through hydrogen bonds. A fat, however, consists largely of hydrogen and carbon in those long chains. Carbon and hydrogen have roughly equivalent electronegativities, and their electron-sharing relationship is relatively nonpolar. Fat, lacking in polarity, doesn’t interact with water. As the butter demonstrated, it just sits there.
There is one exception to that little maxim about fat and water, and that exception is the phospholipid. This lipid has a special structure that makes it just right for the job it does: forming the membranes of cells. A phospholipid consists of a polar phosphate head–P and O don’t share equally–and a couple of nonpolar hydrocarbon tails, as the figure shows. If you look at the figure, you’ll see that one of the two tails has a little kick in it, thanks to a double bond between the two carbons there.
Phospholipids form a double layer and are the major structural components of cell membranes. Their bend, or kick, in one of the hydrocarbon tails helps ensure fluidity of the cell membrane. The molecules are bipolar, with hydrophilic heads for interacting with the internal and external watery environments of the cell and hydrophobic tails that help cell membranes behave as general security guards.
The kick and the bipolar (hydrophobic and hydrophilic) nature of the phospholipid make it the perfect molecule for building a cell membrane. A cell needs a watery outside to survive. It also needs a watery inside to survive. Thus, it must face the inside and outside worlds with something that interacts well with water. But it also must protect itself against unwanted intruders, providing a barrier that keeps unwanted things out and keeps necessary molecules in.
Phospholipids achieve it all. They assemble into a double layer around a cell but orient to allow interaction with the watery external and internal environments. On the layer facing the inside of the cell, the phospholipids orient their polar, hydrophilic heads to the watery inner environment and their tails away from it. On the layer to the outside of the cell, they do the same.
As the figure shows, the result is a double layer of phospholipids with each layer facing a polar, hydrophilic head to the watery environments. The tails of each layer face one another. They form a hydrophobic, fatty moat around a cell that serves as a general gatekeeper, much in the way that your skin does for you. Charged particles cannot simply slip across this fatty moat because they can’t interact with it. And to keep the fat fluid, one tail of each phospholipid has that little kick, giving the cell membrane a fluid, liquidy flow and keeping it from being solid and unforgiving at temperatures in which cells thrive.
Steroids: Here to Pump You Up?
Our final molecule in the lipid fatty trifecta is cholesterol. As you may have heard, there are a few different kinds of cholesterol, some of which we consider to be “good” and some of which is “bad.” The good cholesterol, high-density lipoprotein, or HDL, in part helps us out because it removes the bad cholesterol, low-density lipoprotein or LDL, from our blood. The presence of LDL is associated with inflammation of the lining of the blood vessels, which can lead to a variety of health problems.
But cholesterol has some other reasons for existing. One of its roles is in the maintenance of cell membrane fluidity. Cholesterol is inserted throughout the lipid bilayer and serves as a block to the fatty tails that might otherwise stick together and become a bit too solid.
Cholesterol’s other starring role as a lipid is as the starting molecule for a class of hormones we called steroids or steroid hormones. With a few snips here and additions there, cholesterol can be changed into the steroid hormones progesterone, testosterone, or estrogen. These molecules look quite similar, but they play very different roles in organisms. Testosterone, for example, generally masculinizes vertebrates (animals with backbones), while progesterone and estrogen play a role in regulating the ovulatory cycle.
Double X Extra: A hormone is a blood-borne signaling molecule. It can be lipid based, like testosterone, or short protein, like insulin.
As you progress through learning biology, one thing will become more and more clear: Most cells function primarily as protein factories. It may surprise you to learn that proteins, which we often talk about in terms of food intake, are the fundamental molecule of many of life’s processes. Enzymes, for example, form a single broad category of proteins, but there are millions of them, each one governing a small step in the molecular pathways that are required for living.
Levels of Structure
Amino acids are the building blocks of proteins. A few amino acids strung together is called a peptide, while many many peptides linked together form a polypeptide. When many amino acids strung together interact with each other to form a properly folded molecule, we call that molecule a protein.
For a string of amino acids to ultimately fold up into an active protein, they must first be assembled in the correct order. The code for their assembly lies in the DNA, but once that code has been read and the amino acid chain built, we call that simple, unfolded chain the primary structure of the protein.
This chain can consist of hundreds of amino acids that interact all along the sequence. Some amino acids are hydrophobic and some are hydrophilic. In this context, like interacts best with like, so the hydrophobic amino acids will interact with one another, and the hydrophilic amino acids will interact together. As these contacts occur along the string of molecules, different conformations will arise in different parts of the chain. We call these different conformations along the amino acid chain the protein’s secondary structure.
Once those interactions have occurred, the protein can fold into its final, or tertiary structure and be ready to serve as an active participant in cellular processes. To achieve the tertiary structure, the amino acid chain’s secondary interactions must usually be ongoing, and the pH, temperature, and salt balance must be just right to facilitate the folding. This tertiary folding takes place through interactions of the secondary structures along the different parts of the amino acid chain.
The final product is a properly folded protein. If we could see it with the naked eye, it might look a lot like a wadded up string of pearls, but that “wadded up” look is misleading. Protein folding is a carefully regulated process that is determined at its core by the amino acids in the chain: their hydrophobicity and hydrophilicity and how they interact together.
In many instances, however, a complete protein consists of more than one amino acid chain, and the complete protein has two or more interacting strings of amino acids. A good example is hemoglobin in red blood cells. Its job is to grab oxygen and deliver it to the body’s tissues. A complete hemoglobin protein consists of four separate amino acid chains all properly folded into their tertiary structures and interacting as a single unit. In cases like this involving two or more interacting amino acid chains, we say that the final protein has a quaternary structure. Some proteins can consist of as many as a dozen interacting chains, behaving as a single protein unit.
A Plethora of Purposes
What does a protein do? Let us count the ways. Really, that’s almost impossible because proteins do just about everything. Some of them tag things. Some of them destroy things. Some of them protect. Some mark cells as “self.” Some serve as structural materials, while others are highways or motors. They aid in communication, they operate as signaling molecules, they transfer molecules and cut them up, they interact with each other in complex, interrelated pathways to build things up and break things down. They regulate genes and package DNA, and they regulate and package each other.
As described above, proteins are the final folded arrangement of a string of amino acids. One way we obtain these building blocks for the millions of proteins our bodies make is through our diet. You may hear about foods that are high in protein or people eating high-protein diets to build muscle. When we take in those proteins, we can break them apart and use the amino acids that make them up to build proteins of our own.
How does a cell know which proteins to make? It has a code for building them, one that is especially guarded in a cellular vault in our cells called the nucleus. This code is deoxyribonucleic acid, or DNA. The cell makes a copy of this code and send it out to specialized structures that read it and build proteins based on what they read. As with any code, a typo–a mutation–can result in a message that doesn’t make as much sense. When the code gets changed, sometimes, the protein that the cell builds using that code will be changed, too.
Biohazard!The names associated with nucleic acids can be confusing because they all start with nucle-. It may seem obvious or easy now, but a brain freeze on a test could mix you up. You need to fix in your mind that the shorter term (10 letters, four syllables), nucleotide, refers to the smaller molecule, the three-part building block. The longer term (12 characters, including the space, and five syllables), nucleic acid, which is inherent in the names DNA and RNA, designates the big, long molecule.
DNA vs. RNA: A Matter of Structure
DNA and its nucleic acid cousin, ribonucleic acid, or RNA, are both made of the same kinds of building blocks. These building blocks are called nucleotides. Each nucleotide consists of three parts: a sugar (ribose for RNA and deoxyribose for DNA), a phosphate, and a nitrogenous base. In DNA, every nucleotide has identical sugars and phosphates, and in RNA, the sugar and phosphate are also the same for every nucleotide.
So what’s different? The nitrogenous bases. DNA has a set of four to use as its coding alphabet. These are the purines, adenine and guanine, and the pyrimidines, thymine and cytosine. The nucleotides are abbreviated by their initial letters as A, G, T, and C. From variations in the arrangement and number of these four molecules, all of the diversity of life arises. Just four different types of the nucleotide building blocks, and we have you, bacteria, wombats, and blue whales.
RNA is also basic at its core, consisting of only four different nucleotides. In fact, it uses three of the same nitrogenous bases as DNA–A, G, and C–but it substitutes a base called uracil (U) where DNA uses thymine. Uracil is a pyrimidine.
DNA vs. RNA: Function Wars
An interesting thing about the nitrogenous bases of the nucleotides is that they pair with each other, using hydrogen bonds, in a predictable way. An adenine will almost always bond with a thymine in DNA or a uracil in RNA, and cytosine and guanine will almost always bond with each other. This pairing capacity allows the cell to use a sequence of DNA and build either a new DNA sequence, using the old one as a template, or build an RNA sequence to make a copy of the DNA.
These two different uses of A-T/U and C-G base pairing serve two different purposes. DNA is copied into DNA usually when a cell is preparing to divide and needs two complete sets of DNA for the new cells. DNA is copied into RNA when the cell needs to send the code out of the vault so proteins can be built. The DNA stays safely where it belongs.
RNA is really a nucleic acid jack-of-all-trades. It not only serves as the copy of the DNA but also is the main component of the two types of cellular workers that read that copy and build proteins from it. At one point in this process, the three types of RNA come together in protein assembly to make sure the job is done right.
Have you seen the headlines? Skip them You’ve probably seen a lot of headlines lately about autism and various behaviors, ways of being, or “toxins” that, the headlines tell you, are “linked” to it. Maybe you’re considering having a child and are mentally tallying up the various risk factors you have as a parent. Perhaps you have a child with autism and are now looking back, loaded with guilt that you ate high-fructose corn syrup or were overweight or too old or too near a freeway or not something enough that led to your child’s autism. Maybe you’re an autistic adult who’s getting a little tired of reading in these stories about how you don’t exist or how using these “risk factors” might help the world reduce the number of people who are like you. Here’s the bottom line: No one knows precisely what causes the extremely diverse developmental difference we call autism. Research from around the world suggests a strong genetic component[PDF]. What headlines in the United States call an “epidemic” is, in all likelihood, largely attributable to expanded diagnostic inclusion, better identification, and, ironically, greater awareness of autism. In countries that have been able to assess overall population prevalence, such as the UK, rates seem to have held steady at about 1% for decades, which is about the current levels now identified among 8-year-olds in the United States. What anyone needs when it comes to headlines honking about a “link” to a specific condition is a mental checklist of what the article–and whatever research underlies it–is really saying. Previously, we brought you Real vs Fake Science: How to tell them apart. Now we bring you our Double X Double-Take checklist. Use it when you read any story about scientific research and human health, medicine, biology, or genetics. The Double X Double-Take: What to do when reading science in the news 1. Skip the headline. Headlines are often misleading, at best, and can be wildly inaccurate. Forget about the headline. Pretend you never even saw the headline. 2. What is the basis of the article? Science news originates from several places. Often it’s a scientific paper. These papers come in several varieties. The ones that report a real study–lots of people or mice or flies, lots of data, lots of analysis, a hypothesis tested, statistics done–is considered “original research.” Those papers are the only ones that are genuinely original scientific studies. Words to watch for–terms that suggest no original research at all–are “review,” “editorial,” “perspective,” “commentary,” “case study” (these typically involve one or only a handful of cases, so no statistical analysis), and “meta-analysis.” None of these represents original findings from a scientific study. All but the last two are opinion. Also watch for “scientific meeting” and “conference.” That means that this information was presented without peer review at a scientific meeting. It hasn’t been vetted in any way. 3. Look at the words in the article. If what you’re reading contains words like “link,” “association,” “correlation,” or “risk,” then what the article is describing is a mathematical association between one thing (e.g., autism) and another (e.g., eating ice cream). It is likely not describing a biological connection between the two. In fact, popular articles seem to very rarely even cover scientific research that homes in on the biological connections. Why? Because these findings usually come in little bits and pieces that over time–often quite a bit of time–build into a larger picture showing a biological pathway by which Variable 1 leads to Outcome A. That’s not generally a process that’s particularly newsworthy, and the pathways can be both too specific and extremely confusing. 4. Look at the original source of the information. Google is your friend. Is the original source a scientific journal? At the very least, especially for original research, the abstract will be freely available. A news story based on a journal paper should provide a link to that abstract, but many, many news outlets do not do this–a huge disservice to the interested, engaged reader. At any rate, the article probably includes the name of a paper author and the journal of publication, and a quick Google search on both terms along with the subject (e.g., autism) will often find you the paper. If all you find is a news release about the paper–at outlets like ScienceDaily or PhysOrg–you are reading marketing materials. Period. And if there is no mention of publication in a journal, be very, very cautious in your interpretation of what’s being reported. 5. Remember that every single person involved in what you’re reading has a dog in the hunt. The news outlet wants clicks. For that reason, the reporter needs clicks. The researchers probably want attention to their research. The institutions where the researchers do their research want attention, prestige, and money. A Website may be trying to scare you into buying what they’re selling. Some people are not above using “sexy” science topics to achieve all of the above. Caveat lector. 6. Ask a scientist. Twitter abounds with scientists and sciencey types who may be able to evaluate an article for you. I receive daily requests via email, Facebook, and Twitter for exactly that assistance, and I’m glad to provide it. Seriously, ask a scientist. You’ll find it hard to get us to shut up. We do science because we really, really like it. It sure ain’t for the money. [Edited to add: But see also an important caveat and an important suggestion from Maggie Koerth-Baker over at Boing Boing and, as David Bradley has noted over at ScienceBase, always remember #5 on this list when applying #6.] —————————————————————————– Case Study Lately, everyone seems to be using “autism” as a way to draw eyeballs to their work. Below, I’m giving my own case study of exactly that phenomenon as an example of how to apply this checklist. 1. Headline: “Ten chemicals most likely to cause autism and learning disabilities” and “Could autism be caused by one of these 10 chemicals?” Double X Double-Take 1: Skip the headline. Check. Especially advisable as there is not one iota of information about “cause” involved here. 2. What is the basis of the article? Editorial. Conference. In other words, those 10 chemicals aren’t something researchers identified in careful studies as having a link to autism but instead are a list of suspects the editorial writers derived, a list that they’d developed two years ago at the mentioned conference. 3. Look at the words in the articles. Suspected. Suggesting a link. In other words, what you’re reading below those headlines does not involve studies linking anything to autism. Instead, it’s based on an editorial listing 10 compounds [PDF] that the editorial authors suspect might have something to do with autism (NB: Both linked stories completely gloss over the fact that most experts attribute the rise in autism diagnoses to changing and expanded diagnostic criteria, a shift in diagnosis from other categories to autism, and greater recognition and awareness–i.e., not to genetic changes or environmental factors. The editorial does the same). The authors do not provide citations for studies that link each chemical cited to autism itself, and the editorial itself is not focused on autism, per se, but on “neurodevelopmental” derailments in general. 4. Look at the original source of information. The source of the articles is an editorial, as noted. But one of these articles also provides a link to an actual research paper. The paper doesn’t even address any of the “top 10″ chemicals listed but instead is about cigarette smoking. News stories about this study describe it as linking smoking during pregnancy and autism. Yet the study abstract states that they did not identify a link, saying “We found a null association between maternal smoking and pregnancy in ASDs and the possibility of an association with a higher-functioning ASD subgroup was suggested.” In other words: No link between smoking and autism. But the headlines and how the articles are written would lead you to believe otherwise. 5. Remember that every single person involved has a dog in this hunt. Read with a critical eye. Ask yourself, what are people saying vs what real support exists for their assertions? Who stands to gain and in what way from having this information publicized? Think about the current culture–does the article or the research drag in “hot” topics (autism, obesity, fats, high-fructose corn syrup, “toxins,” Kim Kardashian) without any real basis for doing so? 6. Ask a scientist. Why, yes, I am a scientist, so I’ll respond. My field of research for 10 years happens to have been endocrine-disrupting compounds. I’ve seen literally one drop of a compound dissolved in a trillion drops of solvent shift development of a turtle from male to female. I’ve seen the negative embryonic effects of pesticides and an over-the-counter antihistamine on penile development in mice. I know well the literature that runs to the thousands of pages indicating that we’ve got a lot of chemicals around us and in us that can have profound influences during sensitive periods of development, depending on timing, dose, species, and what other compounds may be involved. Endocrine disruptors or “toxins” are a complex group with complex interactions and effects and can’t be treated as a monolith any more than autism should be. What I also know is that synthetic endocrine-disruptors have been around for more than a century and that natural ones for far, far longer. Do I think that the “top 10″ chemicals require closer investigation and regulation? Yes. But not because I think they’re causative in some autism “epidemic.” We’ve got sufficiently compelling evidence of their harm already without trying to use “autism” as a marketing tool to draw attention to them. Just as a couple of examples: If coal-burning pollution (i.e., mercury) were causative in autism, I’d expect some evidence of high rates in, say, Victorian London, where the average household burned 11 tons of coal a year. If modern lead exposures were causative, I’d be expecting records from notoriously lead-burdened ancient Rome containing descriptions of the autism epidemic that surely took it over. Bottom line: We’ve got plenty of reasons for concern about the developmental effects of the compounds on this list. But we’ve got very limited reasons to make autism a focal point for testing them. Using the Double X Double-Take checklist helps demonstrate that. By Emily Willingham, DXS managing editor
Looking to let go of a little “mommy guilt” for using the television now and then to give yourself a breather? There may be plenty of evidence that leaving children to watch too much television is a bad idea, but there is something to the idea that educational TV is, well, educational. We have the brain scans to prove it!
A study published in PLOS Biology used functional MRI scans to check out the brains of 26 children and 20 adults while they watched 20 minutes of Sesame Street. The actual purpose of the study wasn’t to find out if Sesame Street was educational per se. Rather, it was to observe the neural processes in the brain while a child is learning “naturalistically” and then see whether what they saw could predict how well the children would perform on standardized IQ tests.
Often, participants in studies receive fMRI scans while they are doing some sort of task that is supposed to simulate learning and/or stimulate certain neural processes. For example, a study subject might be asked to put together a three-dimensional puzzle on a computer (so their head remains still enough for the scan) to see how the brain interprets spatial relations.
However, these sorts of oversimplified “lab” tasks are not always representative of real-world activities, so it’s not clear whether what the researchers see on the brain images during these tasks is necessarily indicative of what REAL-life spatial relations thinking looks like. Are the neural processes seen in an fMRI scan while putting together blocks on a computer screen the same as what’s seen in the brain while a person builds a treehouse?
In this study, the researchers found a partial answer to exactly that kind of question, and the answer is no.
The children in study, ranging in age from 4 to 11 and all typically developing, watched the same 20-minute montage of short clips with Big Bird, Cookie Monster, the Count, Oscar and the rest of the gang teaching numbers and letters, shapes and colors, planets and countries, and so on. Meanwhile, the fMRI was taking a snapshot of their brain every two seconds.
The fMRI (which uses a giant magnet, not radiation, to peek into the brain) works by dividing the brain into a 3-D grid so that it can measure the intensity of the brain signals in each little section (about 40,000 of them, called voxels). The researchers collected a total of 609 images of each participant’s brain, which they could then use to map out the neural processes of the participants while they were watching.
They also had the children (23 of them), in a separate fMRI scanning period, perform a one of those lab-only fMRI tasks. In this case, the kids matched isolated pairs of faces, numbers, words and shapes on the computer (they pressed a button if the two images shown matched) while the fMRI images of their brains were created.
Finally, the children (19 of them) took IQ tests that primarily tested their math and verbal skills. Then the researchers analyzed the maps of neural processes in the children and their comparisons with the adults.
They found a couple of interesting things. First, the kids whose neural “maps” were most similar to the adults also performed the best on the IQ tests. This means kids’ brain structure matures in a predictable way, which the researchers called “neural maturity.”
“Broadly speaking, the children showed group-level similarity to adults in cortical regions associated with vision (occipital cortex), auditory processing (lateral temporal cortex), language (frontal and temporal cortex), visuo-spatial processing and calculation (intraparietal cortex), and several other functions,” the authors wrote.
The fMRI scan on the left represents correlations in neural activity between children and adults, in the middle between children and other children, and on the right between adults and other adults. Such neural maps, says University of Rochester cognitive scientist Jessica Cantlon, reveal how the brain’s neural structure develops along predictable pathways as we mature.
Second, the brain maps created during the Sesame Street viewing accurately predicted how the children performed on the IQ tests. Kids who did better on the verbal tasks showed more mature neural patterns in a part of the brain that handles speech and language, called the Broca area. Meanwhile, the kids whose math scores were highest had more neural maturity in a part of the brain that processes numbers, called intraparietal sulcus.
But the researchers’ other finding was that those areas of neural maturity seen during Sesame Street viewing — the ones that matched up with the children’s scores on the IQ test — were not seen during the fMRI task of matching faces, numbers, words and shapes. Basically, the “let’s try to simulate what learning looks like in the brain” task designed specifically for fMRI scans didn’t help much. But the more naturalistic, organic learning that takes places while watching Sesame Street did work.
Researchers now know they can use activities like viewing educational TV to scan children’s brains and learn more about how they learn — and it’s more accurate and helpful than invented computer tasks. It’s possible this technology and research could be applied to understanding better what’s going on with certain learning disabilities.
But a nice additional finding is that, hey, Sesame Street really IS educational! Of course, my son’s favorite show is a different PBS production — Dinosaur Train (which I admit I enjoy too) — so I also feel a better that little D spends a half hour or two, several days a week, learning from Buddy the Tyrannosaurus Rex, Tiny the Pteranodon, Mr. Conductor and Dr. Scott the Paleontologist about dinosaurs, carnivores, herbivores and how to test a hypothesis. All aboard!
The stormy landscape of the breast, as seen on ultrasound. At top center (dark circle) is a small cyst. Source: Wikimedia Commons. Credit: Nevit Dilmen.
By Laura Newman, contributor
In a unanimous decision, FDA has approved the first breast ultrasound imaging system for dense breast tissue “for use in combination with a standard mammography in women with dense breast tissue who have a negative mammogram and no symptoms of breast cancer.” Patients should not interpret FDA’s approval of the somo-v Automated Breast Ultrasound System as an endorsement of the device as necessarily beneficial for this indication and this will be a thorny concept for many patients to appreciate.
If the approval did not take place in the setting of intense pressure to both inform women that they have dense breasts and lobbying to roll out all sorts of imaging studies quickly, no matter how well they have been studied, it would not be worth posting.
Dense breasts are worrisome to women, especially young women (in their 40s particularly) because they have proved a risk factor for developing breast cancer. Doing ultrasound on every woman with dense breasts, though, who has no symptoms, and a normal mammogram potentially encompasses as many as 40% of women undergoing screening mammography who also have dense breasts, according to the FDA’s press release. Dense breast tissue is most common in young women, specifically women in their forties, and breast density declines with age.
The limitations of mammography in seeing through dense breast tissue have been well known for decades and the search has been on for better imaging studies. Government appointed panels have reviewed the issue and mammography for women in their forties has been controversial. What’s new is the “Are You Dense?” patient movement and legislation to inform women that they have dense breasts.
Merits and pitfalls of device approval
The approval of breast ultrasound hinges on a study of 200 women with dense breast evaluated retrospectively at 13 sites across the United States with mammography and ultrasound. The study showed a statistically significant increase in breast cancer detection when ultrasound was used with mammography.
Approval of a device of this nature (noninvasive, already approved in general, but not for this indication) does not require the company to demonstrate that use of the device reduces morbidity or mortality, or that health benefits outweigh risks.
Eitan Amir, MD, PhD, medical oncologist at Princess Margaret Hospital, Toronto, Canada, said: “It’s really not a policy decision. All this is, is notice that if you want to buy the technology, you can.”
That’s clearly an important point, but not one that patients in the US understand. Patients hear “FDA approval” and assume that means a technology most certainly is for them and a necessary add-on. This disconnect in the FDA medical device approval process and in what patients think it means warrants an overhaul or at the minimum, a clarification for the public.
Materials for FDA submission are available on the FDA website, including the study filed with FDA and a PowerPoint presentation, but lots of luck, finding them quickly. “In the submission by Sunnyvale CA uSystems to FDA, the company stated that screening reduces lymph node positive breast cancer,” noted Amir. “There are few data to support this comment.”
Is cancer detection a sufficient goal?
In the FDA study, more cancers were identified with ultrasound. However, one has to question whether breast cancer detection alone is meaningful in driving use of a technology. In the past year, prostate cancer detection through PSA screening has been attacked because several studies and epidemiologists have found that screening is a poor predictor of who will die from prostate cancer or be bothered by it during their lifetime. We seem to be picking up findings that don’t lead to much to worry about, according to some researchers. Could new imaging studies for breast cancer suffer the same limitation? It is possible.
Another question is whether or not the detected cancers on ultrasound in the FDA study would have been identified shortly thereafter on a routine mammogram. It’s a question that is unclear from the FDA submission, according to Amir.
One of the problems that arises from excess screening is overdiagnosis, overtreatment, and high-cost, unaffordable care. An outcomes analysis of 9,232 women in the US Breast Cancer Surveillance Consortium led by Gretchen L. Gierach, PhD, MPH, at the National Institutes of Health MD, and published online in the August 21 Journal of the National Cancer Institute, revealed: “High mammographic breast density was not associated with risk of death from breast cancer or death from any cause after accounting for other patient and tumor characteristics.” –Gierach et al., 2012
Proposed breast cancer screening tests
Meanwhile, numerous imaging modalities have been proposed as an adjunct to mammography and as potential replacements for mammography. In 2002, proponents of positron emission tomography (PET) asked Medicare to approve pet scans for imaging dense breast tissue, especially in Asian women. The Medicare Coverage Advisory Commission heard testimony, but in the end, Medicare did not approve it for the dense-breast indication.
PET scans are far less popular today, while magnetic resonance imaging (AKA MR, MRI) and imaging have emerged as as adjuncts to mammography for women with certain risk factors. Like ultrasound, the outcomes data is not in the bag for screening with it.
In an interview with Monica Morrow, MD, Chief of Breast Surgery at Memorial Sloan-Kettering Cancer Center, New York, several months ago concerning the rise in legislation to inform women about dense breasts, which frequently leads to additional imaging studies, she said: “There is no good data that women with dense breasts benefit from additional MR screening.” She is not the only investigator to question potentially deleterious use of MR ahead of data collection and analysis. Many breast researchers have expressed fear that women will opt for double mastectomies, based on MR, that in the end, may have been absolutely unnecessary.
“There is one clear indication for MR screening,” stressed Morrow, explaining that women with BRCA mutations should be screened with MRI. “Outside of that group, there was no evidence that screening women with MR was beneficial.”
At just about every breast cancer meeting in the past two years, the benefits and harms of MR and other proposed screening modalities come up, and there is no consensus in the field. It should be noted, though, that plenty of breast physicians are skeptical about broad use of MR– not just generalists outside of the field. In other words, it is not breast and radiology specialists versus the US Preventive Services Task Force – a very important message for patients to understand.
One thing is clear: as these new technologies gain FDA approval, it will be a windfall for industry. If industry is successful and doctors are biased to promoting these tests, many may offer them on the estimated 40% of women with dense breasts who undergo routine mammograms, as well as other women evaluated as having a high lifetime risk. The tests will be offered in a setting of unclear value and uncertain harms. Even though FDA has not approved breast MRI for screening dense breasts, breast MR is being used off label and it is far more costly than mammography.
When patients raise concerns about the unaffordability of medical care, they should be counseled about the uncertain benefit and potential harms of such a test. That may be a tall bill for most Americans to consider: it’s clear that the more is better philosophy is alive and well. Early detection of something, anything, even something dormant, going nowhere, is preferable to skipping a test, and risking who-knows-what, and that is something, most of us cannot imagine at the outset.
[Today's post is from Patient POV, the blog of Laura Newman, a science writer who has worked in health care for most of her adult life, first as a health policy analyst, and as a medical journalist for the last two decades. She was a proud member of the women’s health movement. She has a longstanding interest in what matters to patients and thinks that patients should play a major role in planning and operational discussions about healthcare. Laura’s news stories have appeared in Scientific American blogs, WebMD Medical News, Medscape, Drug Topics, Applied Neurology, Neurology Today, the Journal of the National Cancer Institute, The Lancet, and BMJ, and numerous other outlets. You can find her on Twitter @lauranewmanny.] Ed note: The original version of this post contains a posted correction that is incorporated into the version you’ve read here.
The opinions in this article do not necessarily conflict with or reflect those of the DXS editorial team.