<- From
Instead of simply limiting the number of wheels that the child has, we could allow her to have the wheels, but not allow her to use them to make cars. We can do this in a few ways.
First, we can sequester the wheels, perhaps by putting them all in a bag that she can’t open. Second, we can stick something to each of the wheels so that they won’t fit into the cars. Finally, we can stick something into the cars so that the wheels no longer fit. The body uses each of these methods as well.
Showing posts with label medicine. Show all posts
Showing posts with label medicine. Show all posts
Friday, November 26, 2010
The Lego® Model of Pharmacology
In understanding drugs and how they work, it can be helpful to think of the body and its atoms as a giant set of Lego® bricks[1]. A child can use Lego® bricks to make buildings, space ships, cars, etc; and the body can use its atoms to build muscles, bones, signaling molecules, etc. Moreover, just as the child can disassemble her building and then use the bricks to make a car, the body can disassemble its muscle and build bone. Of course, the car requires special bricks (e.g. wheels) which aren’t needed to make a building, and bone needs special atoms (e.g. calcium) which aren’t needed to make a muscle: the number of cars the child can make is limited by the number of wheels she has, and the amount of bone the body can make is limited by the amount of calcium available.
This last point is important. It means that if we want to regulate the number of cars that the child makes, we only need to regulate the number of wheels we allow her to use. We might do this because we have too many cars, and don’t want any more, or we might do so because we don’t have enough buildings (or space ships, or bridges) and want to conserve our bricks to make those instead of cars.
In the body, if we want to regulate the amount of bone we make, we can regulate the amount of calcium there is to make it with. We might do this because we have too much bone, and don’t want any more, or we might do so because we don’t have enough of something else, and want to conserve building materials to make, say, muscle.
Pharmacology (the science of drugs) manipulates the body by interfering with the way it uses its atoms. Continuing with the Lego analogy, drugs are the equivalent of another person adding or removing bricks to the buildings, cars, space ships, etc as they’re being built or after they’re finished; or adding or removing bricks from the box of unused bricks.
[1] Lego® is a registered trademark of the LEGO® Group of companies, which does not sponsor, authorise, or endorse this site
This last point is important. It means that if we want to regulate the number of cars that the child makes, we only need to regulate the number of wheels we allow her to use. We might do this because we have too many cars, and don’t want any more, or we might do so because we don’t have enough buildings (or space ships, or bridges) and want to conserve our bricks to make those instead of cars.
In the body, if we want to regulate the amount of bone we make, we can regulate the amount of calcium there is to make it with. We might do this because we have too much bone, and don’t want any more, or we might do so because we don’t have enough of something else, and want to conserve building materials to make, say, muscle.
Pharmacology (the science of drugs) manipulates the body by interfering with the way it uses its atoms. Continuing with the Lego analogy, drugs are the equivalent of another person adding or removing bricks to the buildings, cars, space ships, etc as they’re being built or after they’re finished; or adding or removing bricks from the box of unused bricks.
[1] Lego® is a registered trademark of the LEGO® Group of companies, which does not sponsor, authorise, or endorse this site
Thursday, November 12, 2009
Why we're asked about eggs when we get the flu shot
When we receive the flu shot (influenza vaccination) we're typically asked a few things, such as are we currently sick, have we ever had Gullian Barre' Syndrome (GBS), and are we allergic to eggs. We're asked if we're sick because the vaccine triggers our immune system, and if we're sick, our immune system is already busy. Depending on how sick we are, perhaps it's better to allow our immune system to finish off our illness before presenting it with the vaccine. We're asked about GBS because having it once suggests that we may get it again. I discuss GBS and the flu vaccine in more detail here. Eggs are my focus on this post, and that explanation requires a little bit of background on how a virus (such as the flu) reproduces (copies itself).
A Little Virology (Study of Viruses)
A cell, whether it's one of the cells in our bodies, or a cell from our pet cat or dog, or whether it is a bacterium (1 bacterium + 1 bacterium = 2 bacteria, and each bacterium is a single cell) contains everything it needs to reporduce. All we need to do is feed the cell, and it does the rest - it repproduces its DNA and all of its internal parts, and then splits into two new cells.
A virus can't do this on its own. It lacks some of the machinery needed to reproduce, and needs to break into a cell and trick the cell's internal machinery into reproducing the virus.
Making the Vaccine - the Chicken Egg Connection
The flu vaccine works by showing a weak or inactivated copy of the flu virus to our immune system, so that if we later see the real flu virus, the immune system can quickly pounce on it and kill it off. As I've said before (see this post for details), the vaccine is kind of like a test prep course for our immune system, where the flu is the actual test: taking the vaccine leaves our immune system better able to take the flu.
The point for this post is that in order to make the vaccine, we need to make a lot of copies of the flu virus, and the easiest way for us to do that is to put the virus in a cell and let the virus do its thing, hijacking the cell and making lots of copies of itself. The cell we use for this is a chicken egg (a chicken egg is a cell).
Since we grow the virus up in a chicken egg, we can end up with some egg in the vaccine itself. So, if someone is allergic to egg, then perhaps the vaccine isn't for them.
A Little Virology (Study of Viruses)
A cell, whether it's one of the cells in our bodies, or a cell from our pet cat or dog, or whether it is a bacterium (1 bacterium + 1 bacterium = 2 bacteria, and each bacterium is a single cell) contains everything it needs to reporduce. All we need to do is feed the cell, and it does the rest - it repproduces its DNA and all of its internal parts, and then splits into two new cells.
A virus can't do this on its own. It lacks some of the machinery needed to reproduce, and needs to break into a cell and trick the cell's internal machinery into reproducing the virus.
Making the Vaccine - the Chicken Egg Connection
The flu vaccine works by showing a weak or inactivated copy of the flu virus to our immune system, so that if we later see the real flu virus, the immune system can quickly pounce on it and kill it off. As I've said before (see this post for details), the vaccine is kind of like a test prep course for our immune system, where the flu is the actual test: taking the vaccine leaves our immune system better able to take the flu.
The point for this post is that in order to make the vaccine, we need to make a lot of copies of the flu virus, and the easiest way for us to do that is to put the virus in a cell and let the virus do its thing, hijacking the cell and making lots of copies of itself. The cell we use for this is a chicken egg (a chicken egg is a cell).
Since we grow the virus up in a chicken egg, we can end up with some egg in the vaccine itself. So, if someone is allergic to egg, then perhaps the vaccine isn't for them.
Saturday, October 24, 2009
The flu
A colleague recently wrote me that he had read my post on the flu vaccine and GBS, and his son had had GBS at age 3.
I am sorry that his son had GBS. It is not a fun condition, and it must be horrifying to see in one's own child. But as a medical professional, and as a public health professional, I have to be very careful not to confuse one patient's experience with what is likely to happen to all, most, or even many patients.
My point on flu vaccine and GBS is that, although there is the possibility of GBS from getting the vaccine, not getting the vaccine leaves people liable to influenza - so the question is, which possibility is greater, and which condition is worse? WHO states that on 1 million vaccinations, 1 case of GBS will result. Last year, (as of 1 July 2008) the US population was 304,059,724(1) - if we had vaccinated everyone, that would translate into 304 cases of GBS; with a fatality rate of 6% (the larger end of the estimate from the CDC, as discussed in the previous post) that would yield 18 deaths total.
On the influenza side, for the 2007 - 2008 season, 88 "Influenza-Associated" pediatric deaths occurred. That's pediatric deaths only - not counting the deaths in young adults, middle aged adults, and the elderly. And this is death from seasonal flu only, not swine flu (also known as H1N1)(2)
So, looking at these numbers, we have 18 vaccination deaths in the entire population, if we vaccinated everyone; or 88 deaths in the pediatric population from the flu itself, plus additional deaths in the adult populations.
I'd rather go with the vaccination.
[Edited 25 October 2009]
Previous post: The flu vaccine and GBS
SOURCE:
(1) http://www.census.gov/popest/states/tables/NST-EST2008-01.xls
(2) http://www.cdc.gov/flu/weekly/weeklyarchives2008-2009/weekly32.htm
I am sorry that his son had GBS. It is not a fun condition, and it must be horrifying to see in one's own child. But as a medical professional, and as a public health professional, I have to be very careful not to confuse one patient's experience with what is likely to happen to all, most, or even many patients.
My point on flu vaccine and GBS is that, although there is the possibility of GBS from getting the vaccine, not getting the vaccine leaves people liable to influenza - so the question is, which possibility is greater, and which condition is worse? WHO states that on 1 million vaccinations, 1 case of GBS will result. Last year, (as of 1 July 2008) the US population was 304,059,724(1) - if we had vaccinated everyone, that would translate into 304 cases of GBS; with a fatality rate of 6% (the larger end of the estimate from the CDC, as discussed in the previous post) that would yield 18 deaths total.
On the influenza side, for the 2007 - 2008 season, 88 "Influenza-Associated" pediatric deaths occurred. That's pediatric deaths only - not counting the deaths in young adults, middle aged adults, and the elderly. And this is death from seasonal flu only, not swine flu (also known as H1N1)(2)
So, looking at these numbers, we have 18 vaccination deaths in the entire population, if we vaccinated everyone; or 88 deaths in the pediatric population from the flu itself, plus additional deaths in the adult populations.
I'd rather go with the vaccination.
[Edited 25 October 2009]
Previous post: The flu vaccine and GBS
SOURCE:
(1) http://www.census.gov/popest/states/tables/NST-EST2008-01.xls
(2) http://www.cdc.gov/flu/weekly/weeklyarchives2008-2009/weekly32.htm
Thursday, October 15, 2009
The flu vaccine and GBS
In 1976, a study showed a possible connection between influenza vaccination (the flu shot) and Guillain-Barré Syndrome (GBS). In GBS, the body attacks its own nervous system, causing weakness and paralysis. Most people recover completely over several weeks or months, but some do have permanent problems, and about five percent of people who get GBS die. So, a connection between influenza vaccination and GBS alarmed a lot of people (and rightly so) because we don't want to be giving people GBS when we vaccinate them against the flu. Since 1976, many other studies have looked for a connection between influenza vaccination and GBS.(1)
Only one study has found a connection: it stated that for every one million people vaccinated against the flu, one person "may be at risk of GBS associated with the vaccine." Not "will get GBS," but "may be at risk." And again, no other studies have found any connections between the vaccine and GBS.(1) (See also (3))
What this means is that there may have been a real connection between the vaccine and GBS. Unfortunately, we cannot rule this out absolutely. there is a chance - a very small chance, but a chance - that today's vaccine is somehow connected to GBS.
Does this mean that we shouldn't get vaccinated against influenza? Not necessarily. To decide whether or not to get the vaccine, we need to look at what might happen if we do get the shot and compare it to what might happen if we don't get the shot. We've already looked at the biggest potential negative of the shot. The smaller negatives include things like redness at the injection site, soreness, headache, etc, most no different from the results of placebo treatment. For a small group of people there is an additional negative - if you’re allergic to something in the vaccine, the vaccine can give you an allergic reaction. (This is why they ask you if you’re allergic to eggs, for instance, since eggs are used in the preparation of the vaccine).
There have also been concerns regarding vaccines and autism. This originated with the MMR vaccine. Hilton, Hunt and Petticrew, writing in 2007, note that
Next, we need to look at the positives of getting the vaccine, and then the positives and negatives of not getting the vaccine. Then we’ll be able to make an educated decision on whether or not to get the vaccine.
The benefits of the vaccine are that it provides protection from the flu, as I discuss in this post. Some readers may also be aware of the study that showed that people who received a flu shot are less likely to die - from any cause - over the following year, but I suspect that this is because that those who receive a flu shot are also receiving better all-around medical care - I doubt that the flu shot is a panacea (a cure for all ills). So for our discussion, we’ll focus on the flu, which means we need to talk about what the flu actually can do to us.
Next up: the flu
Also: Why do we need a flu shot every year?
Edited 16 Oct, 4:40 pm Eastern)
SOURCES:
(1) Centers for Disease Control and Prevention, “Seasonal Flu and Guillain-Barré Syndrome (GBS)” at http://www.cdc.gov/flu/about/qa/gbs.htm, on 13 October 2009
(2) Hilton, Hunt and Petticrew, “Autism: a Focus Group study: MMR: marginalised, misrepresented and rejected?” Archives of Disease in Childhood. downloaded 21 March 2008 from adc.bmj.com
(3) World Health Organization, "Influenza vaccines: WHO position paper." downloaded form http://www.who.int/entity/wer/2005/wer8033.pdf on 16 October, 2009
Only one study has found a connection: it stated that for every one million people vaccinated against the flu, one person "may be at risk of GBS associated with the vaccine." Not "will get GBS," but "may be at risk." And again, no other studies have found any connections between the vaccine and GBS.(1) (See also (3))
What this means is that there may have been a real connection between the vaccine and GBS. Unfortunately, we cannot rule this out absolutely. there is a chance - a very small chance, but a chance - that today's vaccine is somehow connected to GBS.
Does this mean that we shouldn't get vaccinated against influenza? Not necessarily. To decide whether or not to get the vaccine, we need to look at what might happen if we do get the shot and compare it to what might happen if we don't get the shot. We've already looked at the biggest potential negative of the shot. The smaller negatives include things like redness at the injection site, soreness, headache, etc, most no different from the results of placebo treatment. For a small group of people there is an additional negative - if you’re allergic to something in the vaccine, the vaccine can give you an allergic reaction. (This is why they ask you if you’re allergic to eggs, for instance, since eggs are used in the preparation of the vaccine).
There have also been concerns regarding vaccines and autism. This originated with the MMR vaccine. Hilton, Hunt and Petticrew, writing in 2007, note that
The aetiology of autism remains unclear. The suggestion that MMR vaccination may be a cause received wide-spread publicity, although subsequent scientific research has failed to support a link.(2)On a different note, people who get the vaccine sometimes still get the flu - the vaccine matches what the virus looked like when the vaccine was being made, but the virus looks slightly different now. But the vaccine is still useful, since it primes the immune system, and people who get the flu after getting the vaccine have a milder case of the flu - the illness isn’t as bad. So if you’ve ever gotten the vaccine and later gotten sick with influenza, you would have been even sicker without the vaccine.
Next, we need to look at the positives of getting the vaccine, and then the positives and negatives of not getting the vaccine. Then we’ll be able to make an educated decision on whether or not to get the vaccine.
The benefits of the vaccine are that it provides protection from the flu, as I discuss in this post. Some readers may also be aware of the study that showed that people who received a flu shot are less likely to die - from any cause - over the following year, but I suspect that this is because that those who receive a flu shot are also receiving better all-around medical care - I doubt that the flu shot is a panacea (a cure for all ills). So for our discussion, we’ll focus on the flu, which means we need to talk about what the flu actually can do to us.
Next up: the flu
Also: Why do we need a flu shot every year?
Edited 16 Oct, 4:40 pm Eastern)
SOURCES:
(1) Centers for Disease Control and Prevention, “Seasonal Flu and Guillain-Barré Syndrome (GBS)” at http://www.cdc.gov/flu/about/qa/gbs.htm, on 13 October 2009
(2) Hilton, Hunt and Petticrew, “Autism: a Focus Group study: MMR: marginalised, misrepresented and rejected?” Archives of Disease in Childhood. downloaded 21 March 2008 from adc.bmj.com
(3) World Health Organization, "Influenza vaccines: WHO position paper." downloaded form http://www.who.int/entity/wer/2005/wer8033.pdf on 16 October, 2009
Wednesday, October 14, 2009
The flu shot, and why we need it every year
So, we've said that the immune system can learn to recognize pathogens, and that a vaccine teaches the immune system to recognize a pathogen (If you don't remember how or why, see the previous post.) If that's the case, why do we need a vaccine for the flu every year?
It turns out that the flu virus is prone to mutation. This year's flu virus doesn't quite look like last year's virus. The change is enough that even if the immune system will recognize last year's virus (either from a vaccine or from getting the actual illness), it probably won't recognize this year's flu virus. So even if we got last year's vaccine, we need this year's to be protected this year.
Next: aren’t there problems with the flu vaccine?
It turns out that the flu virus is prone to mutation. This year's flu virus doesn't quite look like last year's virus. The change is enough that even if the immune system will recognize last year's virus (either from a vaccine or from getting the actual illness), it probably won't recognize this year's flu virus. So even if we got last year's vaccine, we need this year's to be protected this year.
Next: aren’t there problems with the flu vaccine?
Tuesday, October 13, 2009
Immune system basics
THE BASICS
The immune system can be divided into two parts: the innate (aka non-specific) part and the acquired (aka specific) part. In most textbooks, the acquired part of the immune system receives the most coverage, but the innate part carries most of the weight, so we'll start there.
The non-specific part of the immune system consists of all of the things that keep pathogens (germs) out of the body. It works similarly to the walls and moat surrounding a castle, which work to keep the enemy soldiers out. The non-specific part of the system includes the skin, and also things like the stomach acid (which dissolves any pathogens that we swallow), and lysozyme (which is found in tears, and breaks down pathogens), and mucus (which traps pathogens that we inhale). Most pathogens don't get past these parts of the non-specific immune system. There are also things like fever, and other changes which help the body fight infections, but also make us feel sick, and these can be considered part of the non-specific system as well.
The specific part of the immune system is only activated if a pathogen does sneak past the non-specific part of the system. It is similar to friendly soldiers within the castle walls, whose job is to recognize, hunt down, and destroy any enemies that manage to get inside of the castle. It consists of B cells and T cells, each of which targets a specific pathogen. (A T cell that can target the bird flu virus, for instance, can only target the bird flu virus. A different T cell is needed for chicken pox virus.) When the specific immune system is activated, it also activates those parts of the non-specific immune system (like the fever, etc discussed above) that make us feel sick. (The fever, etc, also serves as a call to arms for the specific part of the immune system.)
TEACHING THE SPECIFIC PART OF THE IMMUNE SYSTEM
The non-specific immune system is always primed and ready - your skin is always there, keeping pathogens at bay. The specific part of the immune system, when we're born, is naive - it can't really respond to anything very well. But, it does learn. Once the specific immune system meets a pathogen for the first time, it remembers it and responds to it much quicker the next time. This is why if the chicken pox virus sneaks past the non-specific part of the immune system once, we get chicken pox. If the chicken pox virus sneaks past the non-specific part of the immune system a second time, the specific part of the immune system recognizes it and pounces on it, killing it before it can really make us sick. We get the chicken pox once, but not twice. (For those of you familiar with shingles and how it relates to chicken pox, I will be getting to that - don't start writing angry comments just yet)
Wouldn't it be great, though, if we could teach the specific part of the immune system to recognize chicken pox without having to actually get the chicken pox that first time? It turns out that we can. We show the immune system a model of the chicken pox virus, and the system learns what the chicken pox virus looks like from the model. The non-specific immune system activates (so we may feel a bit sick, since merely activating the immune system can make us feel sick), and the specific immune system learns to recognize the chicken pox virus. Then, the first time the actual chicken pox virus sneaks past the non-specific immune system, the specific part of the immune system recognizes the virus from the model and pounces on it before it can make you sick.
What is this model? It's a vaccine. The vaccine looks like the actual pathogen, activates the specific part of the immune system (and may make us feel sick briefly) and teaches it to recognize that pathogen, and when the real pathogen comes around, the immune system pounces on it.
Next: The flu shot, and why we need it every year -->
Edited 20 April 2010
The immune system can be divided into two parts: the innate (aka non-specific) part and the acquired (aka specific) part. In most textbooks, the acquired part of the immune system receives the most coverage, but the innate part carries most of the weight, so we'll start there.
The non-specific part of the immune system consists of all of the things that keep pathogens (germs) out of the body. It works similarly to the walls and moat surrounding a castle, which work to keep the enemy soldiers out. The non-specific part of the system includes the skin, and also things like the stomach acid (which dissolves any pathogens that we swallow), and lysozyme (which is found in tears, and breaks down pathogens), and mucus (which traps pathogens that we inhale). Most pathogens don't get past these parts of the non-specific immune system. There are also things like fever, and other changes which help the body fight infections, but also make us feel sick, and these can be considered part of the non-specific system as well.
The specific part of the immune system is only activated if a pathogen does sneak past the non-specific part of the system. It is similar to friendly soldiers within the castle walls, whose job is to recognize, hunt down, and destroy any enemies that manage to get inside of the castle. It consists of B cells and T cells, each of which targets a specific pathogen. (A T cell that can target the bird flu virus, for instance, can only target the bird flu virus. A different T cell is needed for chicken pox virus.) When the specific immune system is activated, it also activates those parts of the non-specific immune system (like the fever, etc discussed above) that make us feel sick. (The fever, etc, also serves as a call to arms for the specific part of the immune system.)
TEACHING THE SPECIFIC PART OF THE IMMUNE SYSTEM
The non-specific immune system is always primed and ready - your skin is always there, keeping pathogens at bay. The specific part of the immune system, when we're born, is naive - it can't really respond to anything very well. But, it does learn. Once the specific immune system meets a pathogen for the first time, it remembers it and responds to it much quicker the next time. This is why if the chicken pox virus sneaks past the non-specific part of the immune system once, we get chicken pox. If the chicken pox virus sneaks past the non-specific part of the immune system a second time, the specific part of the immune system recognizes it and pounces on it, killing it before it can really make us sick. We get the chicken pox once, but not twice. (For those of you familiar with shingles and how it relates to chicken pox, I will be getting to that - don't start writing angry comments just yet)
Wouldn't it be great, though, if we could teach the specific part of the immune system to recognize chicken pox without having to actually get the chicken pox that first time? It turns out that we can. We show the immune system a model of the chicken pox virus, and the system learns what the chicken pox virus looks like from the model. The non-specific immune system activates (so we may feel a bit sick, since merely activating the immune system can make us feel sick), and the specific immune system learns to recognize the chicken pox virus. Then, the first time the actual chicken pox virus sneaks past the non-specific immune system, the specific part of the immune system recognizes the virus from the model and pounces on it before it can make you sick.
What is this model? It's a vaccine. The vaccine looks like the actual pathogen, activates the specific part of the immune system (and may make us feel sick briefly) and teaches it to recognize that pathogen, and when the real pathogen comes around, the immune system pounces on it.
Next: The flu shot, and why we need it every year -->
Edited 20 April 2010
Tuesday, January 13, 2009
Flea treatment
It appears I've been going about flea treatment incorrectly.
From http://dontclickthis.whatingods.name/catproblem.jpg
From http://dontclickthis.whatingods.name/catproblem.jpg
Saturday, August 16, 2008
Give me a saddle, I’ll trade you a car
Earlier this evening I repaired a cassette tape. The repair was simple enough – the leader had broken, but enough of it was left over so that when I opened up the cassette and attached the remaining piece to the reel I’m not already into the brown magnetic portion of the tape every time I press ‘play’, but it led me to thinking about cassette tapes, CDs, mp3s, etc. The benefits of technology, etc. Because although I’ve repaired several tapes, I’ve never yet had to repair a CD. Not that I’d know how, aside from the polishers that I’ve seen for sale. And to repair an mp3? Forget it.
There is a connection here to the difficulty that the medical community presently has with death, though for the moment I forget what it is (I placed the newspaper article down on the computer before I left earlier, since I saw the connection, but now that I’ve returned to the keyboard the thought has flown). And by problem with death, I don’t mean delaying death; I mean deciding when to declare it.
100 years ago, when you were dead, you were dead. No pulse? That’s it; send for the grave-diggers. But then we began to parse death. What do we do with someone who continues to have a pulse, but is irresponsive to all stimuli? Is this person alive? Technology advanced, and things only got messier. Heart-lung machines enable the body, and sometimes the mind to survive periods of death. Heart transplants involved patients living without hearts in their bodies at all, albeit only for the period between when their own heart was removed and the donor heart installed. CPR confused matters as well, as did defibrillation, with their abilities to return a nonbeating heart to proper order.
At the same time, we plunged further into the brain, developing EEGs and debating over the meaning of “brain death”. Some of you will remember the Terri Schiavo case of 2005, which revolved on this issue, among others, but another focus of this discussion is organ donation. Organ viability rapidly declines after perfusion ceases, or even decreases below normal levels. Thus, it is in the best interest of the patient receiving the organs to declare the death of the donor earlier, rather than later. Of course, it is arguably in the best interest of the donor to declare death later, rather than earlier. The same declaration of death must be used for both contexts.
I am here reminded of sub-subatomic particles. The presence of electrons, neutrons, and protons seems obvious to anyone looking at atomic structure, but what about quarks, mesons, etc? Did these only come into being once we shattered our protons and neutrons, much as the shards of a mirror only come into being once the mirror is shattered?
Well, it's late, and I'm tired. I don't know how coherent this is, but I'm off to bed.
Source: Nano, Stephanie. “Doctors Examine When to Declare Organ Donors Dead”. p8B, The Journal News, 14 August 2008 EDIT: in an earlier version of this article it was incorrectly stated that for organ recipients, best practice was to declare the death of the donor later rather than earlier. This is incorrect: organ viability decreases as blood flow decreases, thus donated organs are healthier if harvested earlier. Some spelling errors were also made.
There is a connection here to the difficulty that the medical community presently has with death, though for the moment I forget what it is (I placed the newspaper article down on the computer before I left earlier, since I saw the connection, but now that I’ve returned to the keyboard the thought has flown). And by problem with death, I don’t mean delaying death; I mean deciding when to declare it.
100 years ago, when you were dead, you were dead. No pulse? That’s it; send for the grave-diggers. But then we began to parse death. What do we do with someone who continues to have a pulse, but is irresponsive to all stimuli? Is this person alive? Technology advanced, and things only got messier. Heart-lung machines enable the body, and sometimes the mind to survive periods of death. Heart transplants involved patients living without hearts in their bodies at all, albeit only for the period between when their own heart was removed and the donor heart installed. CPR confused matters as well, as did defibrillation, with their abilities to return a nonbeating heart to proper order.
At the same time, we plunged further into the brain, developing EEGs and debating over the meaning of “brain death”. Some of you will remember the Terri Schiavo case of 2005, which revolved on this issue, among others, but another focus of this discussion is organ donation. Organ viability rapidly declines after perfusion ceases, or even decreases below normal levels. Thus, it is in the best interest of the patient receiving the organs to declare the death of the donor earlier, rather than later. Of course, it is arguably in the best interest of the donor to declare death later, rather than earlier. The same declaration of death must be used for both contexts.
I am here reminded of sub-subatomic particles. The presence of electrons, neutrons, and protons seems obvious to anyone looking at atomic structure, but what about quarks, mesons, etc? Did these only come into being once we shattered our protons and neutrons, much as the shards of a mirror only come into being once the mirror is shattered?
Well, it's late, and I'm tired. I don't know how coherent this is, but I'm off to bed.
Source: Nano, Stephanie. “Doctors Examine When to Declare Organ Donors Dead”. p8B, The Journal News, 14 August 2008 EDIT: in an earlier version of this article it was incorrectly stated that for organ recipients, best practice was to declare the death of the donor later rather than earlier. This is incorrect: organ viability decreases as blood flow decreases, thus donated organs are healthier if harvested earlier. Some spelling errors were also made.
Tuesday, February 5, 2008
The healthcare choices we face
I've already discussed (some of) the reasons why modern Western medicine is so expensive. Now I'd like to discuss some of the choices we're facing.
Simply put, we're up against the law of diminishing returns. We're also facing the reality of several finite resources: money and personnel being two of them.
I'll give several examples:
Keep in mind that care provided to these people cannot be provided to someone else; care for these people is care that is denied to someone else.
These types of decisions appear in medicine every day, several times a day. There is only so much care that can be delivered, and demand outstrips supply. How do we fairly allocate a scarce resource?
Simply put, we're up against the law of diminishing returns. We're also facing the reality of several finite resources: money and personnel being two of them.
I'll give several examples:
- should a 95 year-old, but generally healthy person receive a hip replacement?
- how about a 95 year old in poor health?
- should a chronic smoker be given a lung transplant, given that his smoking (a voluntary act, in theory) is the reason for his lung disease?
- should that smoker be given priority over a patient in need of a lung transplant due to accidental exposure to toxic chemicals?
- or over a 35 year old father of two who was severely injured in a car accident?
- what if the 35 year old had caused the accident because he drove while drunk?
Keep in mind that care provided to these people cannot be provided to someone else; care for these people is care that is denied to someone else.
These types of decisions appear in medicine every day, several times a day. There is only so much care that can be delivered, and demand outstrips supply. How do we fairly allocate a scarce resource?
Saturday, February 2, 2008
Why healthcare is expensive
I just stumbled across this post, about what appears to be a current debate in England regarding what type of medical care should be provided by the state (England has socialized medicine, so in theory, all medical care is provided by the state). Two issues are on the table:
1 - should the state pay for expensive medical care that is unlikely to yield much benefit?
2 - should the state pay for medical care that is needed due to the patient's own folly, e.g. a heart-lung transplant for a chronic smoker?
The writer of the post seems to think that the state should indiscriminately pay for these things. I disagree. But before I go intot he reasons why, I'd like to discuss why medicine is so expensive to begin with.
We have yet to figure out how to pay for all of medical care that people lay claim to. There are a few reasons for this.
* Many people are their own worst enemies when it comes to maintaining their own health. People eat too much of the wrong foods, and not enough of the right ones. People fail to get adequate exercise. People smoke, drink, and fill their bodies with all manner of noxious substances. The result, of course, is poor health.
* Much of modern Western medicine is expensive. CTs and MRIs are useful, but pricey. Lab work can be costly. Pharmaceutical costs can rival mortgage payments. And neither medical education nor malpractice insurance are cheap.
* More medical care is given than is needed. Reasons for this include defensive medicine and patient demand (e.g. demand for antibiotics to treat a common cold).
* Many people without access to a true primary care provider are left using the emergency room for all of their care. ER beds are among the most expensive beds in the hospital, so using one to treat a common cold is extremely wasteful.
* Similarly, the complicated nature of insurance sometimes makes a visit to the ER appear to be the easiest way to go.
* Some people delay seeking medical care (often because they can't afford it, or can do so only with real difficulty) until their problems become severe; severe problems are more costly to treat than minor ones are.
So, our medical costs are high, and in the forseeable future, they are only going to get higher (greying of the population, etc).
Next: the necessary choices we face (link fixed 5 Feb 2008 0207hrs)
1 - should the state pay for expensive medical care that is unlikely to yield much benefit?
2 - should the state pay for medical care that is needed due to the patient's own folly, e.g. a heart-lung transplant for a chronic smoker?
The writer of the post seems to think that the state should indiscriminately pay for these things. I disagree. But before I go intot he reasons why, I'd like to discuss why medicine is so expensive to begin with.
We have yet to figure out how to pay for all of medical care that people lay claim to. There are a few reasons for this.
* Many people are their own worst enemies when it comes to maintaining their own health. People eat too much of the wrong foods, and not enough of the right ones. People fail to get adequate exercise. People smoke, drink, and fill their bodies with all manner of noxious substances. The result, of course, is poor health.
* Much of modern Western medicine is expensive. CTs and MRIs are useful, but pricey. Lab work can be costly. Pharmaceutical costs can rival mortgage payments. And neither medical education nor malpractice insurance are cheap.
* More medical care is given than is needed. Reasons for this include defensive medicine and patient demand (e.g. demand for antibiotics to treat a common cold).
* Many people without access to a true primary care provider are left using the emergency room for all of their care. ER beds are among the most expensive beds in the hospital, so using one to treat a common cold is extremely wasteful.
* Similarly, the complicated nature of insurance sometimes makes a visit to the ER appear to be the easiest way to go.
* Some people delay seeking medical care (often because they can't afford it, or can do so only with real difficulty) until their problems become severe; severe problems are more costly to treat than minor ones are.
So, our medical costs are high, and in the forseeable future, they are only going to get higher (greying of the population, etc).
Next: the necessary choices we face (link fixed 5 Feb 2008 0207hrs)
Tuesday, January 29, 2008
Survival of the most valued
Yesterday on NPR, or perhaps the day before, I heard a spot on the domestication of the cat. Current theory proposes that early, proto-domesticated-cats would have been valued for their abilities to catch and destroy vermin. We can also propose that those cats who were encouraged to stay (or at least, not chased away) would have been those who were the most pleasing to the people in need of vermin control. Part of a cat's appeal would be the nature of its voice, and as cat owners know, there is something appealing in [most] house cats' calls. There is something endearing about the timbre, volume, inflection - something about their calls is socially encouraging.
The speaker compared the socially encouraging nature of house cats' voices to those of wildcats in the zoo, which he found sounded "permanently angry". Truthfully, I might be permanently angry if I was incarcerated in a zoo, and I don't know that I've ever seen a zoo inmate that I'd have called happy, but the point for this discussion is that wildcats, which I gather are genetically similar enough to house cats to successfully mate with them, have voices that are much less pleasant to our ears. The proposal, therefor, is that humans have unnaturally selected house cats for their voices, and for other features we find desirable.
At first glance, this may not seem much different than any form of natural selection - those cats whose traits best enabled them to survive in the world of humans flourished, while those cats who always seemed to be pissed-off failed to survive and procreate. But to look at the issue this way overlooks one key difference. This selection of cats was driven by human intervention. There may not have been a plan behind it, but there was definite intent - "oh, this cat is cute and has a pleasant voice; I think I'll feed it and provide it with shelter."
The phenomenon we describe as natural selection looks only at the relationship between the individual and its environment, and does not consider any guiding intelligence on the part of either. In the case of house cats (and dogs, and domesticated species generally) we find an element of intelligent design, for although we cannot design a species from scratch (yet), we can selectively breed individuals to enhance traits we prefer and reduce traits that we don't. We have hijacked Darwin.
Which leads me to a discussion of healthcare. Individuals who in the natural course of events would die without reproducing are allowed, through the tools and techniques of medicine, to survive, and their genes, including those that made them sickly and inclined to die, are preserved in the gene pool. Thus, instead of naturally shedding undesirable, and even harmful, genes; which would keep the gene pool and the species strong; we keep them and make our species as a whole weaker.
If our medical technology ever gives up or out, then we as a species may be doomed.
The speaker compared the socially encouraging nature of house cats' voices to those of wildcats in the zoo, which he found sounded "permanently angry". Truthfully, I might be permanently angry if I was incarcerated in a zoo, and I don't know that I've ever seen a zoo inmate that I'd have called happy, but the point for this discussion is that wildcats, which I gather are genetically similar enough to house cats to successfully mate with them, have voices that are much less pleasant to our ears. The proposal, therefor, is that humans have unnaturally selected house cats for their voices, and for other features we find desirable.
At first glance, this may not seem much different than any form of natural selection - those cats whose traits best enabled them to survive in the world of humans flourished, while those cats who always seemed to be pissed-off failed to survive and procreate. But to look at the issue this way overlooks one key difference. This selection of cats was driven by human intervention. There may not have been a plan behind it, but there was definite intent - "oh, this cat is cute and has a pleasant voice; I think I'll feed it and provide it with shelter."
The phenomenon we describe as natural selection looks only at the relationship between the individual and its environment, and does not consider any guiding intelligence on the part of either. In the case of house cats (and dogs, and domesticated species generally) we find an element of intelligent design, for although we cannot design a species from scratch (yet), we can selectively breed individuals to enhance traits we prefer and reduce traits that we don't. We have hijacked Darwin.
Which leads me to a discussion of healthcare. Individuals who in the natural course of events would die without reproducing are allowed, through the tools and techniques of medicine, to survive, and their genes, including those that made them sickly and inclined to die, are preserved in the gene pool. Thus, instead of naturally shedding undesirable, and even harmful, genes; which would keep the gene pool and the species strong; we keep them and make our species as a whole weaker.
If our medical technology ever gives up or out, then we as a species may be doomed.
Monday, November 26, 2007
It's all in my head
The thing about depression - well, one thing about depression - is that it saps the patient of the desire for a cure. It's a sort of psychological cancer that causes a slow inward collapse. And for me the implosion often seems to coincide with the end of the semester, when I really need to be productive, and productive in very specific projects, if I want to pass.
The comparison to cancer is particularly apt as psychologocal illness is now where cancer was perhaps 20 years ago. Some of you may recall that we didn't used to talk about cancer; it just wasn't discussed. We've moved past that, as a society, where cancer is concerned, but we're not there yet on psychologocal illness.
Of course, of course, it's all in my head, though...
Q: What did the doctor tell the patient who had brain cancer?
A: "Don't worry, it's all in your head."
The comparison to cancer is particularly apt as psychologocal illness is now where cancer was perhaps 20 years ago. Some of you may recall that we didn't used to talk about cancer; it just wasn't discussed. We've moved past that, as a society, where cancer is concerned, but we're not there yet on psychologocal illness.
Of course, of course, it's all in my head, though...
Q: What did the doctor tell the patient who had brain cancer?
A: "Don't worry, it's all in your head."
Wednesday, October 24, 2007
Weight obsession
I was led to this post from another blog.
Weight is a medical issue. Just about everything becomes more difficult to do as weight increases: the heart has to pump harder, to force blood through more miles (yes - miles) of vasculature; the musculoskeletal system must support and move the additional weight, which it is not prepared to do; the respiratory system is impaired both by extra tissue in the mouth/neck, which can cause sleep apnea, and because an overly large abdomen must be moved out of the way for the diaphragm to drop and the lungs to expand; etc.
And, it's a scientific issue. We are only starting to understand why some people gain weight while others don't. The nature of a proper diet is debated. How to calculate what a person's proper weight is is also unclear. So, weight is a complex issue.
Weight and body size are intimate details of our lives that are on public display every day; anybody we meet in person, anyone who just sees us is instantly informed about how much we weigh - not exactly, but close enough for it to be uncomfortable, particularly in an image-obsessed society such as our own. People whose weight or size are grossly at odds with our ideas of fitness are an easy target for people who feel more secure by pointing out other's faults. The anonymity of the internet only adds to people's boldness.
The same people are also the recipient of well-meaning advice. We are a social people, and we like to advise others, perhaps because it enables us to show off our knowledge. I suspect that often, advice is given more to satisfy a need on the part of the giver, rather than the receiver. Unsolicited advice also carries with it a subtext: "you're screwing up, somehow; I can show you how to do better. Aren't I so helpful, aren't I so superior?
Differentiating between well-intentioned advice and deliberate insult is not always easy. Some remarks fall into both categories. Perhaps they all do. In any event, they often say more about the speaker than about the intended audience.
See here for some more thoughts.
Weight is a medical issue. Just about everything becomes more difficult to do as weight increases: the heart has to pump harder, to force blood through more miles (yes - miles) of vasculature; the musculoskeletal system must support and move the additional weight, which it is not prepared to do; the respiratory system is impaired both by extra tissue in the mouth/neck, which can cause sleep apnea, and because an overly large abdomen must be moved out of the way for the diaphragm to drop and the lungs to expand; etc.
And, it's a scientific issue. We are only starting to understand why some people gain weight while others don't. The nature of a proper diet is debated. How to calculate what a person's proper weight is is also unclear. So, weight is a complex issue.
Weight and body size are intimate details of our lives that are on public display every day; anybody we meet in person, anyone who just sees us is instantly informed about how much we weigh - not exactly, but close enough for it to be uncomfortable, particularly in an image-obsessed society such as our own. People whose weight or size are grossly at odds with our ideas of fitness are an easy target for people who feel more secure by pointing out other's faults. The anonymity of the internet only adds to people's boldness.
The same people are also the recipient of well-meaning advice. We are a social people, and we like to advise others, perhaps because it enables us to show off our knowledge. I suspect that often, advice is given more to satisfy a need on the part of the giver, rather than the receiver. Unsolicited advice also carries with it a subtext: "you're screwing up, somehow; I can show you how to do better. Aren't I so helpful, aren't I so superior?
Differentiating between well-intentioned advice and deliberate insult is not always easy. Some remarks fall into both categories. Perhaps they all do. In any event, they often say more about the speaker than about the intended audience.
See here for some more thoughts.
Thursday, September 6, 2007
Beware the danger of buttered microwave popcorn
My parents don't like butter on their popcorn. We used to have a hot oil popper - this was in the days before the microwave - and at most we'd add a little bit of salt to the finished, popped corn. And for years I believed that this was the way that I liked my popcorn to be. Poor misled fool. Perhaps six months go, I discovered that I do like a bit of butter in my popcorn.
Now buttered (microwave) popcorn is being linked to respiratory infections. It appears that a man ate microwave buttered popcorn twice a day for perhaps ten years, and often intentionally inhaled the steam that escaped when he opened the bag - this steam is high in heated diacetyl, which has long been linked to COPD in popcorn plant workers - lung disease. Apparently his home had diacetyl levels that rivaled those of microwave popcorn plants.
Timing is everything.
But the incident actually reminds me a bit of the current situation with products imported from China, because the link between diacetyl and lung disease is not new; OSHA has long been studying this phenomenon in popcorn plant workers, though they have yet to do anything about it. But now the problem has spilled over to the end user, so now it's a national crisis. The difficulties with Chinese imports started with tainted pet food, then moved to lead paint in toys, and I forget what else. And, China is taking steps to remedy the problem. But, according to an interview I heard on NPR earlier this week (and that I'll have to find a citation for - don't take my word for it until that cite's in place), China's quality control issue isn't new, either: they've been poisoning their own people for years. What's different here is that it is affecting the bottom line as a major importer of China-made articles is growing leary of them.
It's all about the dollar, or your local equivalent - your MU.
And I'm left wondering: does melamine counteract the effects of diacetyl?
Now buttered (microwave) popcorn is being linked to respiratory infections. It appears that a man ate microwave buttered popcorn twice a day for perhaps ten years, and often intentionally inhaled the steam that escaped when he opened the bag - this steam is high in heated diacetyl, which has long been linked to COPD in popcorn plant workers - lung disease. Apparently his home had diacetyl levels that rivaled those of microwave popcorn plants.
Timing is everything.
But the incident actually reminds me a bit of the current situation with products imported from China, because the link between diacetyl and lung disease is not new; OSHA has long been studying this phenomenon in popcorn plant workers, though they have yet to do anything about it. But now the problem has spilled over to the end user, so now it's a national crisis. The difficulties with Chinese imports started with tainted pet food, then moved to lead paint in toys, and I forget what else. And, China is taking steps to remedy the problem. But, according to an interview I heard on NPR earlier this week (and that I'll have to find a citation for - don't take my word for it until that cite's in place), China's quality control issue isn't new, either: they've been poisoning their own people for years. What's different here is that it is affecting the bottom line as a major importer of China-made articles is growing leary of them.
It's all about the dollar, or your local equivalent - your MU.
And I'm left wondering: does melamine counteract the effects of diacetyl?
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