Stories tagged Human Organism

Mar
28
2010

Cell Protein: Illustration of protein chain in the human cell.
Cell Protein: Illustration of protein chain in the human cell.Courtesy Nicolle Rager and National Science Foundation
Science Buzz has had a lot of articles on organ transplants over the years but a new report on liver transplants in children adds a new twist. Currently, severe organ damage or failure requires an organ transplant, preferably one from a donor with a histocompatibility similar to the recipient. In the case of severe liver failure in children, there is often no time to wait for a compatible organ and an incompatible organ is used requiring patients to take anti-rejection drugs (immunosuppression) for the rest of their life. In fact, 70% of all liver transplants require anti-rejection drugs.

Fortunately, the liver is one organ that has the ability to regenerate itself, especially in very young patients. The child patient is given a small section of donated liver, enough to allow the body to function properly, while leaving a small portion of their own liver intact. Hopefully, after a few years, the patient’s original liver will begin to repair and regenerate itself. The doctor can than gradually reduce the quantity of anti-rejection drugs, causing the body to slowly attack and destroy the donated liver segment. Eventually the patient will be removed from anti-rejection drugs completely, have their own liver back, and no signs of the temporary donated liver.

The liver is unique in its regenerative properties; for humans, that is. In other animals, such as amphibians, entire limbs can regenerate. Scientists are researching the role proteins play in cell regeneration in hopes that stimulating certain proteins in other organs of the body will encourage them to regenerate like the liver can.

Mar
25
2010

Painting a new picture of human evolution: A finger bone found in a cave in southern Siberia may add another species to human evolution. (Painting by Charles R. Knight, AMNH).
Painting a new picture of human evolution: A finger bone found in a cave in southern Siberia may add another species to human evolution. (Painting by Charles R. Knight, AMNH).Courtesy Mark Ryan
The bone of a single pinky finger found in a cave in southern Siberia may indicate a new branch in the human family tree. The find could show that besides Neanderthals and Homo sapiens, a third lineage of humans may have shared the ancient landscape of prehistoric Russia.

The piece of finger was found in Denisova cave located in Russia’s Altai mountains by scientists from the Russian Academy of Science. The bone was recovered from sediment layers that have also yielded signs of Neanderthals (Homo neanderthalensis) and modern humans (Homo sapiens). Radiocarbon dating set the age of the layers between 48,000 and 30,000 years old.

Scientists from Germany’s Max Planck Institute and others sequenced 16,569 base pairs of the finger bone’s mitochondrial DNA genome, and the results indicate the new hominen shared a common ancestor with both neanderthals and ancient modern humans sometime around a million years ago. The research team included Michael Shunkov and Anatoli Derevianko, the two Russian archaeologists who discovered the bone in 2008. The study appears in the journal Nature.

Further sequencing of DNA from cell nucleuses will be done next, and could help pinpoint the hominen’s exact origins. If confirmed, the discovery would mean four different species of humans (the 4th would be the Indonesian Hobbit Homo floresiensis) co-existed on Earth some 40,000 years ago.

SOURCE and LINKS
Science Now story
More about human evolution at Becoming Human
Radiocarbon dating

Mar
20
2010

Vitamin D supplement study in children reduced catching flu almost in half

Vitamin D: Calcitriol is the active form of vitamin D found in the body.
Vitamin D: Calcitriol is the active form of vitamin D found in the body.Courtesy JaGa

Last week I blogged about why Vitamin D is needed for health.

This week I came across another study showing that Vitamin D is a flu fighter. The study has just been published online, ahead of print, in the American Journal of Clinical Nutrition.
In the study children were asked to swallow six pills a day (25% dropped out). Half of the children's pills were placebos (fake). The pill givers did not know which pills were fake (double blind).

Incidence of influenza A was 10.8 percent among the 167 kids who received vitamin D pills. That's in contrast to a flu rate of 18.6 percent among an equal number of children getting identical looking inert pills. Doctors monitoring the trial confirmed flu cases using a test to assay for the influenza-A germ.

Vitamin D group had fewer asthma attacks

The study also noted that two asthma attacks occurred during the trial among kids getting the vitamin, compared to 12 in the unsupplemented group. The study doesn’t say whether the same number of kids with a history of asthma were in each group so this result may not be valid.

Better protection after 3 months of Vitamin D

The researchers also stated that it may take almost three months “to reach a steady state of vitamin D concentrations by supplementation". I interpret this to mean that takes our bodies about 90 days to accumulate an effective Vitamin D concentration (less illness after 3 months of taking vitamin D than during initial 3 months).

Mar
16
2010

Old school way of thinking: This idea of man as the be-all, end-all of evolution- the unchanging, final edit of nature- is exactly what the Smithsonian's new exhibition hall is trying to negate.
Old school way of thinking: This idea of man as the be-all, end-all of evolution- the unchanging, final edit of nature- is exactly what the Smithsonian's new exhibition hall is trying to negate.Courtesy wikimedia
The Smithsonian Institute will open a new exhibition hall tomorrow (March 17, 2010), the David H. Koch Hall of Human Origins (this opening coincides with the institute’s 100-year anniversary). The 15,000-square-foot hall will focus on what it means to be human, examining how our defining characteristics emerged over time. One cool thing about the new exhibition (in addition to…everything) is the highlight (in the form of bronze statues) of a-typical hominid species. There’s a statue of Homo heidelbergensis, Paranthropus boisei, and even Homo floresiensis (the “hobbit” species). Now, I know what you’re thinking, “What?! Where’s the Australopithecus africanus?!!” Well, it’s not in this exhibition (at least not in the form of a shiny effigy). The reason for this is to emphasize that our ancestry is not a straight line (as A. africanus might imply because it is a possible direct ancestor of Homo sapiens). Instead, our lineage is much less tidy; there’s species overlap, some species die off… the diagrams are messy. The David H. Koch Hall of Human Origins is trying to get at the fact that we Homo sapiens are just another iteration in our branch-laden tree, not the pinnacle of evolutionary development. I think that’s a great point to remind people of.

Other features of the exhibition include forensically reconstructed life-sized faces of some of our ancestors, 75 skull reproductions, key events in humanity’s evolution (environmental changes, behavioral innovations, etc.), a human family tree, and virtual tours of important research sites. I haven’t had the chance to visit it yet, but the American Museum of Natural History in New York also has a relatively new human origins exhibition. I think it’s exciting that more and more museums are taking on this topic. In the past museums have shied away from it for fear of stirring up controversy. The Milwaukee Public Museum, for example has an exhibit about evolution- it’s on a tiny wall in a dark corner…but at least they have one. It’s important for museums to present scientific research, and the exciting exploration of human evolution is no exception. So if you’re in the D.C. area, be sure to check out the new Smithsonian Hall of Human Origins.

Mar
07
2010

T cell activation
T cell activationCourtesy NIH

Vitamin D necessary to fight disease

When members of our body's immune system called T cells encounter germs and viruses they change into "killer cells" and "helper cells".
A new study published today in Nature Immunology explains why Vitamin D is so important to our health.

"When a T cell is exposed to a foreign pathogen, it extends a signaling device of 'antenna' known as a vitamin D receptor, with which it searches for vitamin D," ...If there is an inadequate vitamin D level, they won't even begin to mobilize."

Most people lack enough Vitamin D

According to a recent study in the Archives of Internal Medicine, found that "77 percent of U.S. adults and teenagers surveyed did not have the estimated minimum healthful level of 30 nanograms per milliliter in their blood. And just three percent of blacks in the survey were getting enough of the vitamin."

Cod liver oil

While living with my parents, I was given a table spoon of cod liver oil, a bowl of oatmeal, and a half of an orange for breakfast each day. I might have to consider adding cod liver oil to my diet again (most people think it tastes nasty).

Mar
04
2010

Athletes like those who won medals at the recent Winter Olympics train intensely for their sport. When most of us think of training, we probably think only of physical exercise, but winning athletes also need to master the mental challenges of competition, which can be especially intense during the Olympic games. After all, the world is watching and nothing short of national pride is on the line.

Listen to the short sound pieces in this New York Times interactive graphic and you'll realize that the distance between winners and losers at the Olympic games is often less than an instant. Being mentally focused and prepared can make all the difference. To help them train, many athletes (including all of the US team) work with Sports Psychologists, mental health experts who help them to prepare for the distraction of crowds and the pressure of the moment. What does mental training involve? Athletes complete exercises in visualization, breathing, body control, and energy management to help them focus so they don't choke under pressure.

What about the mental implications of winning and losing? Psychologists (and economists!) who are interested in knowing more about what makes people happy have used the Olympic games as a kind of laboratory - looking at athletes who take first place and comparing them to those who don't.

As you might guess, winning a Gold medal feels pretty good, and athletes who take first seem to be pretty happy about it. But scientists found an unexpected result in their study on winning, losing, and happiness when they compared silver and bronze medalists - it seems that third place finishers are, on average, happier than those who come in second. Researchers learned this by watching interviews with Olympic athletes at the 1992 summer games and recording words and phrases that they used to describe how they were feeling. They also watched recordings of the facial expressions of the athletes on the podium, and concluded that while most Bronze medalists looked giddy, Silver medalists often seemed disappointed.

Why would you be happier with a third place title than second? Researchers point to a phenomenon called "counterfactual thinking" - in short, it means those in second place are plagued by thoughts of "what might have been" while bronze medalists are relieved that they placed at all. Second place finishers are thinking of the one tiny mistake that cost them first place, while third place finishers are relieved that they didn't make one mistake too many.

This phenomenon is not exclusive to Olympic athletes. We all compete in one sense or another, and have all probably dealt with moments of winning and losing, which is probably part of why we enjoy watching sports games.

Click here for more Buzz stories on science and the Winter Olympics.

Feb
23
2010

There's lots of buzz (normal buzz, not our patented Science Buzz) on the 'net today about the "Bloom Box" featured on 60 Minutes this weekend.

It seemed to me to be a pretty junky interview and feature, but I'm intrigued nonetheless; the Bloom Box is supposed to be an efficient new fuel cell that would allow electricity to be produced at the site where it will be used, eliminating transmission losses, and efficiently converting fuel to energy.

It runs on hydrocarbons, but it sounds like it's pretty omnivorous as to the kinds it can use (so natural gas works, but so would carbon-neutral biogas, etc), and it presumably emits CO2, only much less of it than traditional power generation. (The interview was extremely fuzzy on that aspect, but the Atlantic's article about Bloom from a month ago says that the device does release CO2.)

Something like 20 companies in California are already testing Bloom Box units, and the people making them to have attracted a ton of money, so the technology doesn't look quite so pie in the sky as a lot of other energy inventions we're supposed to get excited about.

The guy behind the Bloom Box believes that, inside of a decade, you'll be able to have one in your basement for something like $3000 dollars. More expensive than a used Super Nintendo, but, as far as major appliances go, pretty darn cheap. We'll see about that, sir... The featured skeptic seems to think that, if we see it at all, we'll see it coming from a company like GE, not Bloom Energy.

Here's the 60 Minutes piece:

Watch CBS News Videos Online

The whole operation has been kept pretty secret until recently, and supposedly there will be more details coming soon.

But until then... What do you think? Ho-hum? Hoax? Or is this something to be excited about?

Feb
21
2010

Nike's new prototype- the retro model: The running foot is soooo 2 million years ago, but you wait long enough and everything comes back.
Nike's new prototype- the retro model: The running foot is soooo 2 million years ago, but you wait long enough and everything comes back.Courtesy perpetualplum
Have you ever run barefoot? It’s great! I’ve never really thought about why I like it, but some really cool biomechanics research coming out of Harvard suggests that there may be some evolutionary reasons for my enjoyment. Homo sapiens and our early ancestors have engaged in endurance running for more than a million years, and have done so with no shoes, or with minimal footwear (sandals, moccasins, etc.). The researchers wanted to know how these early humans (and some humans today, let’s not forget) were able to run comfortably and safely sans shoes. Daniel Lieberman, professor of human evolutionary biology at Harvard, and his crew found that barefoot runners land either on the balls of their feet or mid-foot (the balls of their foot and heel at the same time), while shod runners land on their heels, or heel-strike, to use the lingo. This makes sense when you look at the structure of our feet; our strong, high arch acts like a spring when we run, and this spring can only be loaded when we first land on our forefoot. It wasn’t until the 1970’s when running shoes came equipped with highly cushioned heels that it began to seem normal to run heel-to-toe. (Some research even suggests that not just running shoes, but all shoes are detrimental to our foot health)
With some super advanced equipment (Harvard undergrads are so lucky), Lieberman saw how much of an impact heel-striking causes. When you heel-strike, your foot comes to a dead stop, causing your foot and leg to have to absorb all of that kinetic energy (a force which is 2-3 times your body weight). When you land on your forefoot, however, some of that kinetic energy is converted into rotational energy as your foot goes from toe to heel. This is obviously much less jolting. The researchers hypothesize that heel-striking is the cause of a lot of running-related repetitive stress injuries, and by avoiding heel-striking, more runners could see less of these types of injuries.
If you want to try running barefoot (and I recommend), Lieberman cautions that you shouldn’t just jump into it (especially if it is February in Minnesota), but rather start slowly. Running barefoot uses different muscles and it takes a little while for your feet to get used to it if you’ve been a shod runner your whole life. Who knows, your feet may be your new favorite shoes.

Feb
17
2010

What is it?: It's... ah... you know, whatever.
What is it?: It's... ah... you know, whatever.Courtesy Reytan
Roll up your sleeves and prepare a glass of filtered water, Buzzketeers, because it’s time to learn about the Guinea worm. It’s time to learn about the Guinea worm… hard!

In case the title of this post didn’t spoil it for you already, or if your mother printed out the page but cut off the title, or in case your eyes just don’t read letters that big, the Guinea worm grows to be up to three feet long. Inside you. And even though everything that enters my body must first pass through flame, it still freaks me out.

The parasitic guinea worm, or dracunculiasis (which means “afflicted with little dragons”—you’ll see why in a second), was once found in 20 countries across Asia and Africa, but improved sanitary conditions have reduced its range to just 4 countries in Sub-Saharan Africa. Which is cool, because the Guinea worm is super gross and bad, but not good enough, because the Guinea worm is super gross and bad.

The worm works like this: little worm larvae swim around in puddles and ponds until they get eaten by teeny, tiny crustaceans called copepods (sort of like little shrimp). They live and grow inside the copepods until the copepods get swallowed by people drinking unfiltered water. (Just to be clear, this isn’t just any unfiltered water. If you’ve got electricity to power a computer to read this, there’s pretty much zero chance that there are any worm-carrying copepods in your water. If it came from a tap and not a puddle, you’re probably cool. And even if it came from a puddle, you’re probably still cool.) The copepods get dissolved in the drinkers’ stomach acid, but not the baby worms, which then move from the stomach to the abdominal cavity. There, the worms mate. The male worms die and get absorbed, but the female worms wriggle their way deeper into the body, and grow. And grow and grow. Until they’re about three feet long. They live inside their human host for a year, and then they form a blister somewhere on the surface of the person’s body. When the blister bursts, the female worm emerges just a little bit. The worm releases chemicals that cause the blister to have a very painful burning sensation, and when the host puts the affected area in water to cool it, the worm releases hundreds of thousands of worm larvae into the water, where the cycle can begin again.

As if that whole experience weren’t uncomfortable enough, the treatment isn’t a whole lot better. Because there’s no medicine for Guinea worm infection, the adult worm itself must be removed. The way to do that is to grab the exposed bit of the worm and wrap it around a twig or a piece of cloth, and then twisting the twig. But it has to be done slooooowly so as to not break the worm while it’s still inside your muscles—the process, which is said to be extremely painful, can take up to a month before the worm is fully removed. It’s thought that the ancient symbol for medicine, a snake wrapped around a rod may have been inspired by this procedure.

So, you know… ouch, blech, ouch.

Becoming infected once confers no protection from getting infected again, so people can get Guinea worms over and over again, and in addition to being painful, the blister the worm creates can make the sufferer vulnerable to more dangerous infections.

The good news is that preventing infection is relatively simple; infected people shouldn’t wash in water that will be used for drinking, and simple filters can keep people from ingesting the copepods that carry the worm larvae.

President Jimmy “Billy who?” Carter’s non-profit organization, The Carter Center, has been working for the last 20 years to eradicate the parasite. Despite some pretty significant barriers, it is expected that dracunculialisis will be the second disease, after smallpox, to be completely eradicated through human efforts. (Here’s a recent article on that.)

From what I’ve read (and what the Carter Center says), it looks like humans are the Guinea worm’s only host. So it seems to me that eradicating the infection would cause the extinction of the species. Think about that for a second. Usually sciencey types are pretty much completely against driving other organisms to extinction. But it seems like this one… considering how it pretty much only makes life worse for people who are already dealing with some serious challenges… should maybe… maybe… go extinct? I mean, obviously, right? But try that one on for size; I bet you haven’t often said to yourself that you’re cool with something going extinct. It’s a strange experience.

(If you just can’t deal with it, Here’s a website devoted to saving the Guinea worm. It’s satire, but subtle enough that you could probably play along. But, um, remember that sometimes the Guinea worm emerges from the eyes or genitals of its host. Just saying.)

Feb
09
2010

Playing with fire: Delicious fire.
Playing with fire: Delicious fire.Courtesy esherman
The people of the world wait, their breath held, their tongues clenched between their teeth, open cans of Fresca frozen halfway to their mouths. What do you mean, JGordon? Does soda give me cancer? Or not?

Well?!

Don’t worry, folks. It’s mostly “or not.” Or is it? Or not.

You may have heard (or read—I call it “hearing with your eyes”) that soft drinks might raise your chances of developing cancer. That was probably hard to hear (or read—I call “listening through your face-holes”), because I know you’re generally pro-soda, and generally anti-cancer, and you had been living your life in the hope that there would never be any conflict between the two. You can probably go on living like that, because it’s unlikely that pop is really going to give you cancer, but you should be aware that the world is a complicated place, and your soda and your cancer are sadly not excluded from the complications.

See, a the results of a study out of the University of Minnesota were recently published claiming that there seemed to be a link between the regular consumption of soft drinks (sugar-sweetened carbonated beverages) and a higher incidence of pancreatic cancer. Pancreatic cancer isn’t one of the fun cancers (like, ah, cancer of the… nothing). Although relatively rare, the three-year survival rate for people diagnosed with pancreatic cancer is about 30%, and the survival rate after five years is only 5%.

The study was based on a 14-year survey of 60,524 men and women in Singapore. Of that group, 142 people developed pancreatic cancer. Examining the lifestyles of those who did and did not develop cancer, the researchers found that people who drank two or more soft drinks a week (5 was the average) had an 87% increase in their chances of getting cancer. And because Singapore is a fairly wealthy country with good health care, the scientists think that the results could apply fairly well to western countries as well.

Oh, no! Right? I can’t give up RC Cola!

Well… eh. The thing to keep in mind is it’s all very complicated. Even if there was a direct link between sift drink consumption and pancreatic cancer, your chances of developing the cancer, even as a soda drinker, would still be very small. But, the thing is, there isn’t necessarily a direct link between the two; there’s an association here, but maybe not a causal link. That is, people who drink soda are more likely to get pancreatic cancer, but we don’t know it’s the soda that causes the cancer.

Soft drink consumption itself was associated with behavior like smoking and red meat consumption, so it’s difficult to say that it’s just the soft-drinking (as it were) that contributes to the increased cancer risk.

Researchers do think, however, that it’s possible that soda could be involved in a causal relationship with the cancer. The high sugar levels in soda probably contribute to increased insulin production and presence in the body, which may contribute to pancreatic cancer cell growth. The study also found, however, that there was no association between fruit juice consumption and pancreatic cancer, which sort of makes me wonder. Lots of fruit juice, after all, is very sugary (even if it’s not quite so sweet as most soda). So does it have something to do with the type of sweetener used? Most soda in this country is sweetened with corn syrup, but that’s not necessarily the case in other countries (see Coca Cola for an example), and there’s some debate as to how the body might react to different sweeteners.

Anyway, you aren’t completely taking your life in your hands if you finish that can of Fresca. (Fresca was probably a bad example, seeing as how it uses artificial sweeteners, and will probably give you a totally different kind of cancer.) You’re better off just taking the dip out of your mouth. It’s gross with Fresca anyhow.