Scientific American, March 2012 -- "Lifting the Black Cloud," Robin Marantz Henig
The current class of antidepressant medications, which focus on serotonin and norepinephrine, have limited effectiveness and come with a range of negative side effects. As a result, people suffering from depression often find themselves bouncing from medication to medication, with more or less effectiveness. Henig descibes several novel drug targets that are under investigation, and which promise a future of more choice, and better results for the depressed.
Ketamine is one such substance, which shows promise in speeding neural regeneration in the prefrontal cortex, reducing or reversing the neural atrophy there that often is associated with depression. Acetylcholine is another neurotransmitter that shows promise as a target; ironically, it was one of the first systems targeted for study, but was largely ignored after serotonin showed so much promise. Other drugs target nicotinic repceptors, and seem to be effective at stimulating neural growth in the hippocampus. Finally, another novel research angle is to focus on inflammation, which is often associated with depression.
Tuesday, May 29, 2012
TL;DR - The Mesh Internet
Scientific American, March 2012 -- "The Shadow Web," Julian Dibbell
The internet is powerful, but a little too fragile as-is. In an internet controlled by centralized ISPs, it becomes possible for a strong force, such as a repressive regime or a natural disaster, to bring the network down. Dibbell describes an alternate approach to the current centralized system (which, incidentally, is much closer to its original formulation). A mesh network relies on point users, people with a network connection, owning their own networking hardware. Once the community of users becomes large enough, the network becomes resilient to attack or damage, such that many different nodes can go down without affecting the overall network activity. These mesh networks are currently being developed, and are available for ~ 150$, but costs are expected to go down soon. Dibbell points out that this would not be a replacement of the ISP model, but rather would provide a poor-man's substitute, maximizing basic access and providing competition to induce the ISPs to improve service and pricing.
The internet is powerful, but a little too fragile as-is. In an internet controlled by centralized ISPs, it becomes possible for a strong force, such as a repressive regime or a natural disaster, to bring the network down. Dibbell describes an alternate approach to the current centralized system (which, incidentally, is much closer to its original formulation). A mesh network relies on point users, people with a network connection, owning their own networking hardware. Once the community of users becomes large enough, the network becomes resilient to attack or damage, such that many different nodes can go down without affecting the overall network activity. These mesh networks are currently being developed, and are available for ~ 150$, but costs are expected to go down soon. Dibbell points out that this would not be a replacement of the ISP model, but rather would provide a poor-man's substitute, maximizing basic access and providing competition to induce the ISPs to improve service and pricing.
TL;DR - A Cure for HIV?
Scientific American, March 2012 -- "Blocking HIV's Attack," Carl June & Bruce Levine
In 2009, many headlines were grabbed by a medical story in which a man--the so-called "Berlin Patient"-- was cured of HIV after receiving a bone marrow transplant. June and Levine explain this case, and why we're still not entirely sure what exactly happened, and elaborate on the work that they and others have done to conceptually follow up on this treatment angle.
HIV reproduces by hijacking the body's immune system, invading T cells and using their cellular machinery to make copies. But some people are lucky enough to be completely resistant to HIV, not showing signs of infection despite repeated exposures. It turns out that this is because of a genetic mutation that disables the CCR5 protein from being expressed on T cell membranes. Without this protein, HIV lacks an entry point into the T cells, eliminating its reproductive pathway. The Berlin Patient was a man who had both HIV and lymphoma, and so was a candidate for a bone marrow transplant. This involves killing off his existing bone marrow with radiation and then injecting donor bone marrow (which must be a close enough genetic match that the body will accept and use it). In this case, the bone marrow was selected to be from a donor who also happened to have the rare genetic mutation leading to an absence of CCR5 protein, and this seems to be what led to the elimination (possibly) of HIV from the recipient's system. This is all tentative, unfortunately, due to the fact that we can't be sure whether the HIV has been eliminated, or is just hiding somewhere we can't find it, that other aspects of the treatment (such as radiation) could have killed off or reduced the HIV, and that this match was such a statistical rarity that a replication is very hard to produce.
However, it may be possible to artificially cripple the CCR5-coding portion of the genetic code, resulting in gene therapy wherein the patient's own genetic material is extracted, altered, and reintroduced. This might be a much more efficient, and safer, way of achieving the same sort of results.
In 2009, many headlines were grabbed by a medical story in which a man--the so-called "Berlin Patient"-- was cured of HIV after receiving a bone marrow transplant. June and Levine explain this case, and why we're still not entirely sure what exactly happened, and elaborate on the work that they and others have done to conceptually follow up on this treatment angle.
HIV reproduces by hijacking the body's immune system, invading T cells and using their cellular machinery to make copies. But some people are lucky enough to be completely resistant to HIV, not showing signs of infection despite repeated exposures. It turns out that this is because of a genetic mutation that disables the CCR5 protein from being expressed on T cell membranes. Without this protein, HIV lacks an entry point into the T cells, eliminating its reproductive pathway. The Berlin Patient was a man who had both HIV and lymphoma, and so was a candidate for a bone marrow transplant. This involves killing off his existing bone marrow with radiation and then injecting donor bone marrow (which must be a close enough genetic match that the body will accept and use it). In this case, the bone marrow was selected to be from a donor who also happened to have the rare genetic mutation leading to an absence of CCR5 protein, and this seems to be what led to the elimination (possibly) of HIV from the recipient's system. This is all tentative, unfortunately, due to the fact that we can't be sure whether the HIV has been eliminated, or is just hiding somewhere we can't find it, that other aspects of the treatment (such as radiation) could have killed off or reduced the HIV, and that this match was such a statistical rarity that a replication is very hard to produce.
However, it may be possible to artificially cripple the CCR5-coding portion of the genetic code, resulting in gene therapy wherein the patient's own genetic material is extracted, altered, and reintroduced. This might be a much more efficient, and safer, way of achieving the same sort of results.
TL;DR - Saving Energy for Later
Scientific American, March 2012 -- "Gather the Wind," Davide Castelvecchi
Renewable energy is definitely the future, but there are still many problems to be worked out before it can take over from fossil fuels. One major concern is the reliability of energy sources; what happens when the wind calms, or the sun goes down? Modern energy usage demands consistency, which renewables often lack. Storing energy for later is the obvious way around this, and Castelvecchi reviews five different proposed solutions, each receiving ratings from an expert panel on measures of scalability, cost-effectiveness, and efficiency.
Pumped hydro (pumping water uphill for potential energy) and compressed air (pumping air into rock formations and caverns for later extraction) are two methods that are currently in use, and which show significant promise, though certain limitations, such as geological and geographical considerations, hinder their large-scale deployment. Battery technology is advancing strongly, as well, though it will inevitably be costly. I'd heard about thermal storage--storing heat in molten salt--before, though it, too has some technological hurdles to jump. Finally, home hydrogen conversion (using small-scale systems to break down water into hydrogen at off-peak rates) is an interesting idea, though it is the one that has furthest to go before it's a practical solution.
Renewable energy is definitely the future, but there are still many problems to be worked out before it can take over from fossil fuels. One major concern is the reliability of energy sources; what happens when the wind calms, or the sun goes down? Modern energy usage demands consistency, which renewables often lack. Storing energy for later is the obvious way around this, and Castelvecchi reviews five different proposed solutions, each receiving ratings from an expert panel on measures of scalability, cost-effectiveness, and efficiency.
Pumped hydro (pumping water uphill for potential energy) and compressed air (pumping air into rock formations and caverns for later extraction) are two methods that are currently in use, and which show significant promise, though certain limitations, such as geological and geographical considerations, hinder their large-scale deployment. Battery technology is advancing strongly, as well, though it will inevitably be costly. I'd heard about thermal storage--storing heat in molten salt--before, though it, too has some technological hurdles to jump. Finally, home hydrogen conversion (using small-scale systems to break down water into hydrogen at off-peak rates) is an interesting idea, though it is the one that has furthest to go before it's a practical solution.
TL;DR - The Giants of Utah
Scientific American, March 2012 -- "Dinosaurs of the Lost Continent," Scott Sampson
Sampson details paleontological work that he and others have done in western North America, stretching from Alberta to Mexico, that suggests that in the Cretaceous era there were multiple (~ 17-20) species of giant (>1 ton) dinosaurs cohabitating. Why this is surprising is because at the time, these dinosaurs were sharing a continent--Laramidia--that was significantly smaller than present-day North America, and which, based on understandings of current species, should have been too small to sustain that number of species. As a comparison, current-day Africa is only able to sustain about 6 giant species. Two main theories have been advanced to explain this: either the dinos were much more efficient than present-day mammals (possibly being cold-blooded, or maybe lukewarm-blooded), or the flora of the time was much more productive (the climate would have supported a hothouse environment at mid latitudes).
Sampson details paleontological work that he and others have done in western North America, stretching from Alberta to Mexico, that suggests that in the Cretaceous era there were multiple (~ 17-20) species of giant (>1 ton) dinosaurs cohabitating. Why this is surprising is because at the time, these dinosaurs were sharing a continent--Laramidia--that was significantly smaller than present-day North America, and which, based on understandings of current species, should have been too small to sustain that number of species. As a comparison, current-day Africa is only able to sustain about 6 giant species. Two main theories have been advanced to explain this: either the dinos were much more efficient than present-day mammals (possibly being cold-blooded, or maybe lukewarm-blooded), or the flora of the time was much more productive (the climate would have supported a hothouse environment at mid latitudes).
TL;DR - To The Ends of the Universe
Scientific American, March 2012 -- "The Far, Far Future of Stars," Donald Goldsmith
The universe had a beginning, and will, ultimately, have an end (...probably). Fortunately we're living somewhere in the middle, because this is where it gets exciting. Goldsmith describes theoretical predictions and models of how the universe will develop over the coming billions and trillions of years, in which we'll see (okay, we probably won't be around, but maybe someone will see) a dramatic decrease in the rate of star formation. Yet as stars mature, the rate of production of heavy elements will ramp up, which will ultimately fuel an increase in planetary formation--Goldsmith claims that 1/2 to 2/3rds of the planets that will ever exist have not yet been created. With many more planets, despite the fact that they will in general be orbiting weaker suns, there will be many more chances for appropriate conditions for fostering life to arise. So before we get to the predicted "not with a bang, but with a whimper" slow heat death of the universe, it may become a much more lively place.
TL;DR - Jumping Genes in the Brain
Scientific American, March 2012 -- "What Makes Each Brain Unique?", Fred Gage & Alysson Muotri
Gage and Muotri describe mobile elements, or "jumping genes," short genetic segments that are able to be cut/copied and reinserted into DNA. This can have several possible effects on the genetic code, introducing amino acid substitutions, repeats, or stops in coding regions, changing a given protein, or altering noncoding regulatory region, changing how much a given protein is expressed.
Mobile elements are active only in reproducing cells, meaning their effects are often seen in the gonads, but they're also particularly active in the brain at sites of neurogenesis, such as the hippocampus. Gage and Muotri (or the editors) play up this element to argue that these genetic differences are what contribute brain differences, even in identical twins. I think this is a bit of an overstatement on their part, however. The environment, or the unique experiences a person has, has direct and continuing effects on the development of the brain. As such, mobile elements can help explain how this process occurs, and why the effects of even the same environment can differ among individuals (especially given the random nature of mobile elements), but it's only a part of the picture.
Gage and Muotri describe mobile elements, or "jumping genes," short genetic segments that are able to be cut/copied and reinserted into DNA. This can have several possible effects on the genetic code, introducing amino acid substitutions, repeats, or stops in coding regions, changing a given protein, or altering noncoding regulatory region, changing how much a given protein is expressed.
Mobile elements are active only in reproducing cells, meaning their effects are often seen in the gonads, but they're also particularly active in the brain at sites of neurogenesis, such as the hippocampus. Gage and Muotri (or the editors) play up this element to argue that these genetic differences are what contribute brain differences, even in identical twins. I think this is a bit of an overstatement on their part, however. The environment, or the unique experiences a person has, has direct and continuing effects on the development of the brain. As such, mobile elements can help explain how this process occurs, and why the effects of even the same environment can differ among individuals (especially given the random nature of mobile elements), but it's only a part of the picture.
Blogging the Backlog
I'm currently sitting on a large stack of magazines and journals that I've been meaning to go through. In the next few weeks I'll be making a concerted effort to get through them -- find what's interesting -- but I've also decided to take this as an opportunity to flex my writing muscles. So I'll be writing up a series of blog posts focusing on the interesting info I pick up in my reading. They'll be shorter than a usual writeup--more of an abstract than a full exploration--but often one of the best ways of figuring out (and remembering) an article is to focus on the big picture.
First up, the March issue of Scientific American.
First up, the March issue of Scientific American.
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