Archive for the 'Science-y stuff' category

To live deep and suck out all the marrow of life

Aug 13 2010 Published by under [Medicine&Pharma], Cancer, Medicine, Science-y stuff

There are few procedures in medicine more complex, dangerous, and remarkable than stem cell transplantation. This procedure has enabled us to successfully treat cancers that were previously uniformly fatal. For certain types of acute myeloid leukemia, for example, stem cell transplant increases 5-year survival from less than 15% to about 44%.

But the full story of stem cell transplant is much more complicated.  The data are complicated and the research is full of fits and starts, new questions and dead-ends.

Chimera. Apulian red-figure dish, ca. 350-340 BC. The Louve, Paris, France. Image from Wikimedia Commons

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2 responses so far

Cancer 201--treatment basics

Aug 05 2010 Published by under Cancer, Science-y stuff

Once a cancer has been diagnosed, we must use our knowledge of biology, medicine, and clinical trials to plan treatment. Treatment can be curative or palliative (that is, with a goal of reducing symptoms or extending life, rather than effecting a cure).

Understanding cancer treatment requires a little bit of basic biology, and as with all of my more "science-y" posts, please forgive any oversimplification (but please also note that this complexity stands in stark contrast to the simplistic altmed cancer "cures"), or for overtopping the head of the hapless non-scientist.

As you recall from Cancer 101, cancer is a proliferation of abnormal cells. This fact alone, that the cells are actively dividing, gives us a target for therapy.

Cells go through particular phases in their lifetimes, but these phases aren't as simple as "birth, growth, death". The life of a cell is roughly divided into the cell cycle, during which the cell is preparing for and conducting cell division, and the G0 (G sub zero, or G-naught) phase, where the cell simply goes about all of it's non-reproductive business, such as structural support and protein production. Normal tissue has a fairly balanced growth fraction, that is the number of cells dividing is roughly equal to the number of cells being lost (to normal programmed cell death and other normal attrition). Cancerous tumors have a higher growth fraction than normal tissue, that is the number of cells in cycle is higher than the number of cells being lost (to programmed cell death, etc.).

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Cancer 101

Aug 03 2010 Published by under Cancer, Science-y stuff

Cancer is the second leading cause of death in the U.S., and at any moment directly affects almost 4% of the population, or about 10.8 million Americans. A diagnosis of cancer can be one of the most frightening moments in someone's life, and yet most people understand little about the disease. I hear the same questions about cancer over and over again, so it's well past time to give a bit of an explanation of this set of diseases.
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Why I am not a primatologist

Mar 17 2010 Published by under #FWDAOTI, Science-y stuff

One of the things I love about the blogosphere is the give and take, the ability of people to comment on each others' work, and the diversity of topics. The conversations that take place in the blogosphere have real value (a value which is so far under-recognized and under-utilized). Without the blogosphere, I would never be exposed to many of the things I read online, such as basic research in neuroanatomy and drug abuse, physiology, and primatology.
Interest in primatology is sort of like love of chocolate---I suspect most of us are born with it. As the Bare Naked Ladies sang, "Haven't you always wanted a monkey?" I suspect that the more an animal appeals to us, either as being similar or being cute, the more we tend to endow it with human characteristics. We are narcissistic both as individuals and as a species, and we see more value in an animal the more "human" it is.
I think anyone would be hard-pressed to say that a bonobo is not more like us than an opossum. But that doesn't mean that bonobos are little people. We are---I think rightly---more likely to respect the needs of humans than other animals, and we tend to create an informal hierarchy of which animals can be treated in which ways, often based on our perceptions of an animal's ability to perceive and understand noxious stimuli. Most of us feel comfortable swatting a mosquito just because it bothers us, but few of us would approve of killing a chimpanzee just because it looks at us funny. A high school biology student may cut paramecia into bits to see what happens and sleep well that evening, but if they were asked to do the same to an ape, they would likely balk (I hope).
These admittedly obvious and somewhat unsophisticated observations arose because of a post I read today over at the Primate Diaries. In it, Eric Michael Johnson uses a clever writing device to argue for a moral stance greater than humanism, one that explicitly places us face-to-face with non-human primates.

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57 responses so far

Transposition of the Great Arteries

Aug 24 2009 Published by under Medicine, Science-y stuff

OK, it's time for another science-y post. Usually, I take on something very relevant to my specialty---it's a helluva lot easier to write about stuff I already know. But some basics are just really cool, and worth exploring, even though I'll have to step a bit outside my comfort zone. In this case, it's the heart.  Because I'm venturing a bit on the wild side, I consulted an expert, whose hot, hot science helped illuminate this topic.

If you've taken a basic biology course, you probably have some idea of how the human heart works, but understanding can be a bit deeper if we look at the heart through the lens of things that can go wrong.

The heart is one the most easily recognized and, yet, mysterious organs in the human body.  Physicians of the Hippocratean school first described the valves of the heart in the 4th century B.C.  Since, the heart has historically been described as the core of love,spirituality, intellect, and emotion.  The heart was originally thought to be the source of conscious thought.  The heart is a recognizable icon, source of stress for some of us who have witnessed friends and family with cardiovascualr disease, and a subject of poetry and song.  However, to the physician and physiologist, the human heart is simply a pump whose primary purpose is the circulation of blood throughout the circulatory system.  In fact, the majority of cardiac physiology and pathology (disease) can be easily demystified and understood by thinking of the heart as a mechanical pump.

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Human heart, post-mortem obviously

The heart is a pump

The heart has one basic function -- to receive oxygen poor blood from the body, pump it to the lungs where it can be replenished with oxygen, and then pump it back to the body where that oxygen is needed.  

If we sliced through the human heart we would find that it has four compartments or chambers.  The top chambers, or atria (singular = atrium), receive the blood.  The lower chambers, or ventricles, pump the blood.

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Human heart from Gray's Anatomy showing the four chambered heart.

The following diagram illustrates how blood travels through the heart:

blood path.gif

 

 Image courtesy Isis the Scientist

  1. Oxygen poor blood returns from the body and enters the right atrium
  2. Oxygen poor blood passes from the right atrium to the right ventricle.  The right ventricle then pumps the oxygen poor blood into the pulmonary artery.   Sometimes people are confused by the pulmonary artery because most people think of arteries as having oxygen rich blood.  The true definition of "artery" is any vessel that takes blood away from the heart.
  3. Oxygen poor blood from the pulmonary artery travels to the lungs where the oxygen is replenished.
  4. Oxygen rich blood returns from the lungs and enters the left atrium
  5. Oxygen rich blood passes from the left atrium into the left ventricle.  The left ventricle then pumps oxygen rich blood into the aorta.
  6. Oxygen rich blood from the aorta is then circulated through out the body.  The oxygen is utilized and the blood becomes oxygen poor.  Return to step 1 and begin the cycle again. 

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Cancer 202---Radiation therapy

Jun 28 2009 Published by under Cancer, Medicine, Science-y stuff

(NB: as is usual with my more "science-y" posts, oversimplification is the rule. --PalMD)
It's been a very long while since I've updated my series on cancer. I keep meaning to, but you know how things go. Lately, though, I've been curious about radiation oncology, the use of ionizing radiation to treat cancers. What set me off was a recent Times article about some pretty crappy practices. Radiation oncology requires a very thorough education in physics and medicine and the field attracts some of the best minds, but no field is immune to unethical behavior (which in this case I feel is more important than the incompetence itself).
Anyway, radiation---it scares the crap out of people. We call magnetic resonance imaging "MRI" instead of the original "NMR" (nuclear magnetic resonance) mostly because the idea of being in a machine with the word "nuclear" on it freaks people out. Of course, radiation is a normal part of living. We are exposed to high energy electro-magnetic radiation daily, both from the Earth and from space. If fact, ionizing radiation from the sun is the primary cause of skin cancer.
Very shortly after ionizing radiation was discovered in the late 19th century, it was applied to the treatment of cancerous tumors, albeit in a very crude way. As knowledge of physics and medicine grew, so did the sophistication of treatments. Early on, of course, it wasn't understood exactly how radiation damaged living tissue. If you aim x-rays at healthy skin for long enough the skin starts to turn red in a way similar to a sun burn. If you want to get that radiation to a tumor somewhere under the skin, then simply aiming an x-ray at the skin above it is going to kill skin long before it kills tumor. Thankfully, people are rather clever. In the early 20th century, doctors tried inserting radium directly into tumors, and tried fractionating treatments of external beam radiation so that each individual dose was not too toxic to the overlying structures. These techniques allowed killing more tumor cells than normal cells.
But let's back up a little here and examine some of the basics.

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9 responses so far

What is disease? Diabetes, diagnosis, and real science

Jun 09 2009 Published by under Medicine, Science-y stuff

ResearchBlogging.orgOne of the concepts we often discuss around here is "what is disease?" As we've seen in the discussion of Lyme disease and so-called Morgellons syndrome, this is not always an easy question to answer. Knowing what states are disease states does not always yield a black-or-white answer. The first step is usually to define what a disease is. The next problem is to decide who in fact has that disease. The first question is hard enough, especially in disease states that we don't understand too well. The second question can be equally tricky. To explore the scientific and philosophical issues of diagnosing an illness we will use as a model diabetes mellitus (DM). This won't be quite as boring as you think, so don't click away yet. (Most of the information here refers more specifically to type II diabetes, but most of it is valid for type I as well.)

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Syphilis---the king of spirochetes

May 06 2009 Published by under Medicine, Science-y stuff

All this talk of Lyme disease is getting me all excited about spirochetes. Borrelia burgdorferi, the bacterium that causes Lyme disease, is a spirochetal bacterium, and so is Treponema pallidum, the spirochete that causes syphilis. Now, if you're thinking syphilis is all about sores on the naughty bits, you're missing the best parts of the story. Syphilis is a rather serious and common disease, and can increase the transmission of other STD's such as HIV. If left untreated it can be disabling and deadly.

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Treponema pallidum, the bacteria that causes syphilis. How cool is that? (courtesy the CDC)

T. pallidum cannot be cultured outside of the human body. That means unlike Strep, for instance, we can't just grow it in the lab and watch what it does. Much of our knowledge of the disease was acquired during the pre-antibiotic era and from the infamous Tuskegee Syphilis Study.

Anyway, the disease we call syphilis is divided into three stages, each of which is fascinating on its own. In contrast to, say, "chronic" Lyme disease, antibodies can be detected in the blood of people with this disease, and correlate with disease activity.

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What we have here...

Apr 16 2009 Published by under Medicine, Science-y stuff

Science is hard. It often requires us to put aside our beliefs and preconceptions to more accurately understand how the world works. But it is not in any way unimaginative. To paraphrase a wildly brilliant guy, every time a scientist formulates a hypothesis, she must imagine a different world. It can be a very creative process.
We advocates for science are often accused of being unimaginative and uncreative. This is false. We are also accused of being closed-minded. This is false. But it is also true. Scientists are very skeptical. To quote one of our regular readers:

To state the good ideas one embraces is not enough. One must explain what is rejected and why. Science is not a method for accepting what is true. It's a method for rejecting what is false. So what therapies...do you reject? What standard do you use to reject those ideas?

This is a concept that I've never stated quite so clearly. It is one that those involved in cult medicine do not understand. To have a clever idea is one thing, but you must have some logical way of separating the wheat from the chaff, and the sorting cannot be done by whim. We're talking about people's lives here, and if you offer up homeopathy, say, and your excuse is "well, we don't have the data yet, but we will some day," then you do not deserve the honor of serving your fellow human beings.
And it is an honor---an honor and a privilege, and if your default position is not one of compassionate skepticism, you're going to hurt someone.

38 responses so far

Sit right down and we'll speak the unspeakable

Apr 06 2009 Published by under Medicine, Science-y stuff

The news reports are cryptic. One news report about Farah Fawcett's cancer went on for five paragraphs before they told us what type of cancer. Cancer is a tough enough diagnosis---there is still a fear and stigma associated with the "C" word which may lead to people putting off diagnosis and treatment. This effect may be magnified when the cancer occurs on the "naughty bits", such as the breasts, vulva, penis, or in Farah Fawcett's case, the anus (at least according to news reports). In general, the later a cancer is diagnosed, the worse the prognosis, so it's important to reduce this stigma. With that in mind, let's shed some light on anal cancer. (And yes, there are pictures of anuses below the fold---they won't kill you.)

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15 responses so far

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