Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!


Forgot your password?

Combining Nanotech and Radiology 125

Twilight1 writes "According to this article at CNN, researchers are testing a microscopic "smart bomb" to target, attack, and kill cancer cells. It's quite fascinating that they are using radioactive by-products from the production of nuclear power and weapons as the effective payload."
This discussion has been archived. No new comments can be posted.

Combining Nanotech and Radiology

Comments Filter:
  • When I was a kid (Score:2, Informative)

    by seann ( 307009 )
    I saw this last night on @Discovery.ca, and it reminded me when I saw this on some TV show, this must of been my grade 6 (7 years ago).

    I'm glad to see they finally have this in practical use.
    • I dunno about "practical" use. Unless you're a vet who specializes in mice. . .
      • Practical as in "not on the drawing board".

        They can make mice breath underwater, they can make a dog's head twitch hours/days after it has deceased.

        We can't get 200% out of fusion yet.
        We can't goto the moon commercialy and seamlessly as going to another country.
  • Normal cells (Score:3, Interesting)

    by Reality Master 101 ( 179095 ) <RealityMaster101@@@gmail...com> on Friday November 16, 2001 @06:19PM (#2576800) Homepage Journal

    Perhaps a biologist can answer a question I've had about this, which is also related I suppose to Chemotherapy.

    What is the difference between a cancer cell and a "normal" cell? Why would radiation therapy tend to kill cancer cells faster than normal cells? The article mentions that they are concerned that normal cells might be affected, but they don't explain why it would favor cancer cells in the first place.

    • Re:Normal cells (Score:5, Informative)

      by Edgy Loner ( 44682 ) on Friday November 16, 2001 @06:28PM (#2576840) Homepage

      Radiation, chemotherapy and the like are more likely to kill cells during division. Cancer cells divide all the time, hence are more sensitive to these agents. Most normal cells don't divide as much and aren't as senstive. Exceptions would be hthe cells that line the gi tract and form hair follicles. Which is why rad/chemotherapy tends to make people losse their hair.
      • There are additional reasons (besides targeting of radiation and susceptability of dividing cells to DNA damage due to activation of otherwise-idle genes) for cancer cells to be more susceptable to radiaion damage.

        Because cancer cells are dividing all the time, they tend to be less robust than other cells. Many therapies (including some of the earlier chemotherapy regimens) take advantage of this by poisoning cells ALMOST to the point of death - which pushes cancer cells over the edge. (An exception to this rule is Melanoma, which gets extra energy as a side-effect of making the brown pigment Melanin. This makes it STRONGER than the typical cell.)

        Radiation therapy can provoke some of the further-damaged cancer cells into triggering an immune reaction against both themselves and their still-undamaged-but-cancerous neighbors.


        It's nice to see that the monoclonal-antibody-attached-to-local-poison approach is getting into the field. But I'd like to know what happened to:

        - Monoclonal antibodies plus radio-iodine for Melanoma. (Sounds like this is the same stunt further tuned, with a different radioactive element for more localized effect.)

        - Monoclonal antibodies plus a catalytic poison from a bacterial toxin. (I don't recall the exact toxin used. But it worked by destroying all the copies of one of the enzymes that attached a particular amino-acid to its T-RNA, shutting down protein synthesys. One molecule, one dead cell. And the molecule ended up inside the cell when the cell recycled the part of the surface with the antibody attached. Perhaps that had a variable effectiveness depending on what the antibody targeted. Radiation works from OUTSIDE too, even if you need a lot more copies of it.)
    • IANAB but AFAIK (more acronyms to follow) cells know when to divide and how far to grow (they tend to stop when they bump into other cells). Cancer cells don't express this protein correctly (or don't react to the protein's presence, I can't remember which) and just keep growing and divinding regardless of their surroundings. The smart bomb may be able to differentiate by trying to bind at the protein receptor site for the "Stop growing" protein. If it binds, the cell is normal. If it doesn't, kill it.

      As for how this may of may not effect other tissue, it may simply be a matter of collateral damage. Cancer cells grow among normal cells.

      I'm not a biologist, I just played one in college.


    • Cancer cells multiply abnormally fast, causing tumors. To accomplish this rapid proliferation, they replicate DNA more than normal cells. Ionizing radiation and chemotherapy often (always?) target DNA. By damaging DNA or causing manufacture of defective DNA, they preferentially affect cells that are multiplying rapidly. Many of the side effects are due to destruction of tissues with high rates of multiplication such as bone marrow and gut.
      • Just as an aside:

        Chemotherapeutics (at least, some anthracyclines) not only muck around with DNA, but can lead to free radical generation & can damage cellular membrane components.

        They're nasty, nasty molecules.
      • By damaging DNA or causing manufacture of defective DNA, they preferentially affect cells that are multiplying rapidly.

        IANAME (not a med expert) but "defective DNA" sounds suspiciously like "mutated DNA" which sounds suspiciously bad. Of course, I've got no experience with this, and if I get cancer I'll do what the doctor says, but can anyone here explain how/why it's safe to cause "defective DNA"?
        • It isn't safe, of course. Traditional chemo is a balance between killing the tumor and killing the patient. There are well-established long-term side effects of chemo, and they're not always pleasant...but, for most of the cancers that we treat that way, the choice is between dealing with those side effects and dying.

          By the way -- if you live long enough to get cancer, don't "just do what the doctor says". Chemo works, and it does save lives, but make the effort to educate yourself. There are lots of different treatments, some of them experimental, and you can frequently benefit from finding the treatment that's right for your particular case.
        • Some cancer treatments do mutate DNA, and it is bad in general. Killing bad cells can work out for the best. Other DNA damage might involve replacing one or more of the usual bases (A, T, G & C) with some other chemical. IIRC, 5-fluorouracil (5FU), a chemotherapy drug, gets incorporated in place of thymine in replicating DNA. Some AIDS drugs work similarly. Inducing fatal mutations and DNA defects might be beneficial if the cancer cells suffer much more than normal cells.
    • While I'm sure someone else could answer this far better than I, I'll give it a shot, as I studied skin cancer for a bit of time.
      In regards to skin cancer anyway, a cancer cell is developed when the DNA helix inside the cell becomes damaged and mutates, causing the normal C,G,T,&A bonds to break and reform in ways they shouldnt. Tada, you have a cancerous cell. Now when the cell adjacent to the cancer cell dies, it can either be replaced by the mitosis-spawned cell of a healthy cell in the surrounding area, or the aforementioned mitosis-spawned cancer cell. If it gets replaced by the cancer cell, then the process can keep repeating until a large number of cells are cancerous. Tada, you have a tumor. In skin cancer cases, the mutation usually occurs from heavy sunlight exposure.
      In regards to your second question, I'm not totally sure, but I believe the radiation kills off the cells that have improper DNA helixes faster than regular helixes. Someone please correct me I am wrong.
    • I'm not sure if I have all of this exactly right, but I'll give it a shot.

      Cancerous cells are mutant cells which divide at a higher rate than is normal. Normal cells have mechanisms that control the rate at which they divide. Normal cells also have genes that cause them to kill themselves if they become cancerous. Cancer happens when through mutations a cell has faulty copies of the anti-cancer genes. People can be genetically predisposed to get cancer if they inherit some faulty anti-cancer genes (but still have some working ones).

    • What is the difference between a cancer cell and a "normal" cell? Why would radiation therapy tend to kill cancer cells faster than normal cells?
      The quick answer - it doesn't. Enough of the radiation used will kill ANY cell, with no preferences.

      Conventional radiation therapy involves sending radiation from multiple directions (not necessarilly at the same time), such that the cancerous tissue is at the focus and gets the most radiation, while normal tissue around the cancer isn't in every beam, and is more likely to survive.

      This new method uses antibodies that will (hopefully) attach only to the cancerous cells as part of the carrier. Because 75% of the radiation only occurs _after_ the first decay of the actinium, and because the alpha radiation from the actinium does NOT propagate very far through tissue, then almost all of the radiation is concentrated on the cancerous tissue.

      As an aside, a similar article [newscientist.com] is at NewScientist.com [newscientist.com]
    • There are two reasons this particular therapy favors cancer cells over "normal cells"

      First: the caged actinium-225 is attached to a monoclonal antibody. The antibody (or, in their case, 4 antibodies) binds very nicely to a specific receptor/molecule. Ideally, this receptor/molecule is ONLY found on cancer cells, and not on healthy cells. In practice, this isn't ever the case - but there are a number of receptors which are more prevalent on cancer cells than normal cells. There are a couple of FDA approved anti-cancer treatments which make use of monoclonal antibodies (such as Mylotarg and Herceptin).

      Second: Why does radiation kill cancer cells faster than normal cells? Well - 'radiation' does bad things to DNA - it can cause strand breaks, or base-pair dimer formation. These sorts of things happen all the time in cells, and they have a number of repair mechanisms to take care of just these sorts of problems, if they have enough time (and the damage isn't too severe). In cancer, cells are typically dividing as fast as they possibly can, since the normal regulatory checkpoints which govern cell division are often missing or damaged. Often, cancerous cells will even have problems with their DNA repair mechanisms. So - the repair mechanisms don't have time to fix the damage before the cell replicates its DNA or divides. The result of faulty or incomplete DNA synthesis is unpredictable, but often bad - in other words, the cell dies.

      By the way, the journal article can be found here. [sciencemag.org]
    • What is the difference between a cancer cell and a "normal" cell?

      Actually, this is one of the problems with treating cancer cells, they are simply regular cells that have broken down. There are a few general trends common to most cancer cells, however. Cancer cells are cells which divide without control or order and go on to invade and damage nearby tissues and organs. They can also break away and invade other parts of the body.

      Because they are usually dividing more rapidly than normal cells, scientists can take advantage of this fact. Every time a cell divides it has to make a copy of its genetic material, such as DNA. Just like all other things in the world, every time a copy is made there is a chance of mistakes being made. By introducing radiation and chemicals you can increase the chances of a mistake being made. Thus a large number of cancer cells which would have been viable are now not able to live and die off. When combined with other treatments and the body's natural defenses, radiotherapy can go a long way toward sending a patient into remission.

      Better targeting of the cancerous cells is important, however, because radiation also affects normal cell division. You can see this in the most rapidly dividing cells in our bodies, the hair, skin, stomach, and bone marrow, among others. Radiation hits all cells in the body hard and causes cell death all over, but more so in these rapidly dividing cells. This is why hair falls out, skin gets rough and lesioned, red and white blood cell counts drop, etc. It still hits cancer cells harder than normal cells, but if you can target the cancer cells with a better delivery mechanism then you will do less damage to the patient during treatment.

    • Re:Normal cells (Score:2, Insightful)

      by Versalius ( 3953 )
      There can be myriad differences between cancer cells and normal cells or there can be very few differences. This is one of the reasons that cancer is so difficult to treat. In general cancer cells multiply faster than "normal" cells; therefore, they have an increased rate of DNA turnover and metabolism. Usually, both radiotherapy and chemotherapy rely on this phenomenon.

      Radiation at sufficient levels and many forms of chemotherapy cause damage to DNA. Normal, slower replicating cells usually have time to repair this damage. Faster replicating cells pass this damaged DNA on to their progeny unrepaired and, hopefully, the cell will eventually die. So, broken down to its most base form both chemo and radiation are poisons and the medical staff tries to walk a fine line of killing the cancer cells before the poisons kill the normal cells.

      Vesalius M.D.
    • From the article: When the nanogenerator is injected into the body, it travels through the blood stream until the antibody locks onto a cell and the entire complex moves inside the cell.

      The research shows that antibodies are effective delivery agents for selecting cancerous cells. In lab animals, at least.

    • Radiation tends to damage DNA.

      This damage can be repaired by a cell given enough time, but you have to repair the damage before you replicate.

      Since cancer cells are growing rapidly and most cells are growing slowly the cancer cells will be much more likely to replicate the damaged DNA and end up dead.
    • Is it just me, or are these biologists a terribly orderly bunch?
    • If you look at the article, they attached the thing to an antibody that locks onto cancer cells. Also, they used an atom with a half-life of, IIRC, a few weeks - plenty of time for it to get inside the cancer cell before emitting too much radiation. An alpha particle is very damaging, but can only go a very short distance through flesh; thus, it'll really goof up the cell it is released in, but not cause a lot of general harm.

      ONE alpha particle can ionize everything it passes, releasing 'free radicals' which do even more damage; I wouldn't be surprised if a single one could kill a cancer cell.
    • Ionising radiation creates highly reactive free radical molecules that damage cell proteins, particularly causing breaks in the DNA. Single-strand breaks can be repaired perfectly because the DNA is still held together by the other strand of the double helix. The cell division process can fail, cause damage or kill the cell if it occurs when the DNA is broken. Thus, rapidly dividing cells, which have less time to repair damage, suffer more damage from ionising radiation. Alpha particles create so much ionisation in their short path (millimeters) that double strand breaks are created. Double strand breaks are much harder to repair and cause permanent damage (mutations) to healthy cells. Some of these mutations are cancerous. Hence, alpha emitters, such as plutonium and radon gas, are highly carcinogenic. The advantage of using alpha emitters in this case is that their range in body tissues is very short and they deliver their dose to the region targeted by the antibodies.
  • Seriously, we just found the answer to storing some of our Nuclear Waste. We'll store it in our bodies. Nevermind it stays in the body -- even after it has done its job, and there is no way to insure that the right cell will be targeted!
    I think I will stick to the other methods like Kemo and seed impants if I ever get cancer.
    • Dude, even Chemo is bad for you. This just makes me fucking ill and reminds me of that line said by Bones in Star Trek IV about how our medical science is still in the dark ages, or something.

      If there is a god out there, have mercy on us, please? Polluting our bodies with nuclear waste, WONDERFUL.
      • Morons. (Score:2, Interesting)

        You idiots.

        You totally missed the point.

        The element in use is actinium. The particular isotope decays rapidly, and leaves no left over damaging radiation, so this whole 'polluting our bodies with nuclear waste' crap is out of line.

        As far as it not know which cells are the right cells, wrong again. Ever heard of monoclonal antibodies? Did you read the article and do a little research before you responded? no. So shut the hell up.

        The buckyball-like cage prevents radiation from harming cells that don't exactly match the monoclonal attachment, i.e. normal cells aren't targeted.
        • While I agree by and large, there will be some SMALL amount of damage to normal cells. Some of the alpha particles will make it outside of the cancer cell, or be released before the 'cage' finds the cancer cell.

          That said, every drug known (from caffeine on up) causes some tiny amount of damage to the body; anyone who's drunk 5 shots of espresso in a setting will agree with me :)

          Traditional chemotherapy pretty much incapacitates the patient while it is in progress, and can leave them sterile or with other permanent effects. If this works, and is safer - not necessarily perfectly safe - for the same degree of effect against cancer, there is no reason not to use it.

          We're all getting a constant low dose of radiation. The desk on which I'm typing this is made of wood, and thus contains some amount of radioactice carbon 14, which is emitting gamma rays and neutrons throughout my body. The pasta I just ate is doing the same. That doesn't mean it'll kill me.
      • Funny, there's been a cure for cancer around for centuries. It's called CLEAN AIR AND WATER and HEALTHY FOOD. Too bad we'll probably never see this cure produced.
        • Bullshit.

          First of all, define "Clean air and water" and "Healthy food" for me.

          If the so-called "dirty air and water" we consume are undeniable conclusive causes of cancer, then why do relatively few people die from it? Why doesn't everyone die from cancer since our air and water are so terrible?

          So my aunt ate healthy for much of the latter portion of her life. She didn't smoke or drink, and she exercised regularly. Then we see my father, 2 years older than her, been eating the so-called "junk food" all of his life. He starts his day with a bottle of pepsi and a package of snack cakes. He smoked 3 packs of cigarettes a day at one time, but has since quit. He doesn't know the meaning of exercise. "Experts" would have you believe you'd be dead at 30 if you led his lifestyle. He's 62 and still works every day. Aunt Betty died 6 years ago.

          So like...try thinking before you write something patently stupid.
          • You make a good point, but it's not a proof, and it's no less stupid than what I wrote.

            The reason goes deeper than smoking, exercise, or polluted air and water.
            Not everyone is affected the same way by "contamination". Some people can smoke 3 packs a day and live 80 years, and some will, as you say, live till they're 30.
            Genes and inheritance play a large role.

            What makes you think we aren't all affected by pollutants? Maybe we'd all be happy, outgoing and friendly people if we had a clean atmosphere. Who the hell knows? Do you want to wait until something's proven before doing anything about it? And let me remind you, it may not be proven within your lifetime.
            Excuse me for having an open mind. It's rare these days.
    • The right cell will be targeted because I assume these buckyballs bond to the antigens unique to cancer cells. Healthy tissue would get a small dose,but it wouldn't cause any damage. Chemotherapy's side effects are much worse than this. People are WAY to paranoid about radiation.
  • by FatAlb3rt ( 533682 ) on Friday November 16, 2001 @06:21PM (#2576811) Homepage
    i wonder if the fact the mice were glowing made sleep difficult?
  • I think that this is a very interesting venue in the treatment of cancer. Even though the radioactive atom "eventually becomes harmless and remains in the body," I still think it highly possible that this treatment may be nullified by the radiation emitted by the nanogenerators. Hopefully this is not the case, and we will have found an effective and non-harmful (minimally so, at least) treatment for cancer.
    • The half life is relatively short. I think its on the order of a month. I know it decays to a different radioactive isotope within 10days, which then decays to a stable form fairly quickly.
    • Maybe they can turn that evil technology once held by Alex Krychek into something useful, something to save mankind even! And it's all controlled with a PDA...
    • Nanogenerators?? good grief. The scientists involved seem to be taking quite a bit of license to make it appealing to the general public. The radioactive atom doesn't 'power' anything.

      Radiation therapy (along with chemotherapy) is really a brute force method for dealing with cancer. You use radiation or chemicals to kill cells. It just happens that the cancer cells get killed off faster than normal cells.

      The principle of radioimmunotherapy (tagging antibodies with radiactive elements) has been around for quite some time now. The only new and revolutionary part of this particular project seems to be that the radioactivity is encased in a buckyball which is tagged to the antibody. I suspect this is to help keep the activity attached to the antibody. One of the major problems with existing tags is that the radioactive decay breaks the bonds attaching the atoms to the antibody so you end up with a bunch of free radioactivity floating around the body instead of attached to the antibody.
  • Just like how a certain percentage of people don't respond at all to Chemotherapy, it would be interesting to see what percentage of people respond positively to this once it becomes available.

    Of course, the first problem with cancer is that in a large majority of cases, by the time the cancer is discovered, it has spread throughout the body far too much to be effectively treated. Even with this promising technique, early detection is still the best hope for many people.
    • This other article [mskcc.org] seems to suggest that all of the mice tested had their lives extended ..

      Many of the animals had long-term survival, and all of them had their lives extended after asingle treatment at a low dose.

      Nanodot [nanodot.org] is an okay source for people who dig this kind of stuff.
    • Actually, one of the greatest benefits of radioimmunotherapy compared to conventional radiation therapy is that it's much better at treating metastatic cancers. Since the radiation is attached to antibodies, it will circulate through the blood and attach to cancerous cells wherever they happen to be. That makes it a great technique for treating cancer that's spread beyond its initial tumor. A slight modification to the technique can also be used for diagnosis; they use a different isotope, one that emits gama-rays rather than alphas, and then use a gama-ray sensitive camera to image where the isotopes wind up. That lets them find out where the cancer has spread.

  • How does it know the difference between cancer cells and normal cells?
    • Each cage is linked to an antibody. Antibodies are raised against a particular molecule, such as some section of protein in a pollen coat. Most likely, the antibody linked to the cage binds some molecule that is expressed by cancer cells much more than normal cells.
  • Finally they found something to do with all that nuclear waste besides burying it like cats in a giant sandbox.
  • Biology Question (Score:3, Interesting)

    by brunes69 ( 86786 ) <slashdotNO@SPAMkeirstead.org> on Friday November 16, 2001 @06:29PM (#2576845) Homepage

    I've been wondering this for some time. Cancer cells are cells which multiply indefinatly, as opposed to normal cells, which only multiply for a specified amoutn of time, and then die off (with the exception of stem cells). Correct? Ok. Well' if I am right so far, can someone tell me why more research isn't going into controlling cancer, rather than destroying it? Like, I would think, if you could start and stop the cancer effect at will, you could live forever. Am I totally off base?

    • Not necessarily. Tissue like nerve tissue doesn't grow. If it's damaged, you're screwed. I guess in theory you could extend the life of some organs this way, but certain other ones, like the brain or CNS don't repair themselves (w/out great amounts of help from modern medicine)


      • Actually, you're dead wrong. Nerve cells do regrow (although spinal cords tend to need a LOT of help, they're only learning how to do that one).

        There was a recent discoveery made that brain cells actually do continue to divide and populate the brain (they tested this in monkeys by injecting them with dye, so that the dye would only show up in new tissues. Scanning the brain, they found large deposits of this dye). Check the archives, I'm sure it was on slashdot.

        Not to mention that most people who've had nerve damage after surgery will tell you about the "electric shocks" they feel 6-8 months afterward (the nerves regrowing and reconnecting, the area starts becoming sensitive again).

    • The growth of individual cells in a cancerous tumor is quite different from the controlled expression of cells developing into tissue. Simply controlling cancer cell growth to a slower rate (i.e. a rate of replacement) would not necessarily be beneficial.
      The whole in this case is greater than the sum of the parts. For example: If you grew new nerve cells in the brain, the growth would be deleterious to the existing synaptic infrastructure thus destroying the patterns of the connections.
    • You're right on the money. This is one of the hottest (if not the hottest) areas of cancer research right now.

      Just do a google search on "antiangiogenisis".
      Many, many people are working on ways to slow down or stop cancer cell reproduction. In conjunction with other therapies you could still possibly erradicate the cancer, or at the very least it would become a chronic, but controllable condition.

      There are lots of these sorts of drugs in clinical trials rught now.
    • Re:Biology Question (Score:2, Informative)

      by raffymd ( 19140 )
      I'm rephrasing your question as "Can cancer be beneficial by providing immortal properties to an organism?" The answer is no because transformed cells (cells that have been deemed cancerous due to their uncontrolled replicative potential) lose their "differentiated" ability. That is, they stop functioning like they were supposed to. For example, a tumor in the liver (which decided to stop growing) is not beneficial to the liver because it doesn't do what liver cells are supposed to do (like synthesizing digestive and metabolic enzymes, etc.) If anything, it steals resources like nutrients away from functioning liver cells nearby. This tumor may not be lethal but it certainly isn't helpful.
      • Actually, you often get what are called (I think, I forget if this is the correct name) bioactive tumours, which still perform one or two of their original functions.

        So you'll get somebody with WAY to much adrenal function, or some pituitary hormone going berzerk. Most cancers don't work this way, but specific types do.

    • by mgv ( 198488 )
      Cancer cells are cells which multiply indefinatly, as opposed to normal cells, which only multiply for a specified amoutn of time, and then die off (with the exception of stem cells). Correct?

      Its a little more complex.

      Normal DNA has caps on the end called telomeres, which don't code for anything directly, but act as a lead in type message for DNA replication (The enzymes have to know where to start replicating DNA from).

      Each division fails to fully replicate the Telomeres, which shorten and ultimately lead to a form of (cellular) aging where further cell replication cannot occur.

      Enzymes called telomerases can repair the DNA, and stem cells express this. Cancer cells also must repair the telomeres or they will die. This (might) be a possible cause for cancers to spontaneously resolve - my guess here on this one but I'd love feedback.

      A cell may not have to divide to live on. Brain and muscle cells generally don't divide, which gives you a certain stability in your shape and thinking processes. They can live for 100 years in an arrested (G0) phase of the cell division cycle. They die mostly because of their choice to do so, a process called apoptysis, which clearly has more benefit than you might think at first.

      Well' if I am right so far, can someone tell me why more research isn't going into controlling cancer, rather than destroying it?

      Lots of research has gone into this. There are drugs currently in use that renormalise cancer cells including retinoids and thiolidamide, to name a few.

      Like, I would think, if you could start and stop the cancer effect at will, you could live forever?

      We are already living much longer than we were designed for. Average lifespan has increased tremendously over the last few hundred years from 20 years to 70-80 years. Death is no longer a thing that comes from nowhere or in response to the environment. Now it is considered more of an intrinsic clock in a person.

      There are several impediments in the way of acheiving immortality:

      The sun will engulf the planet. The universe is finite. You will die, get over it.

      Secondly, gene therapy wont help if you stand in front of an oncoming truck. Death can still come from without as well as within.

      Thirdly, ageing occurs at many levels. For example, the eye is a largely non living optical instrument. The denaturing of protiens in the lens causes presbyopia (age related long sightedness) in most people in their forties. The treatment for this will probably not be gene therapies (except perhaps to grow whole new eyes), but rather lens implants. Other (mostly) non living parts of your body include tendons, heart valves and teeth, all of which can wear out and do not heal. If it wasn't alive to start with, this technique won't repair it.

      Fourthly, other forms of agening occur, such as scarring and stretching. Skin stretching and loss of elasticity has a profound effect on our outward appearance but has little to do with cellular ageing. Similar changes internally lead to blood vessel diseas such as aneurysms.

      A little long winded, but hope that this helps.


  • by EccentricAnomaly ( 451326 ) on Friday November 16, 2001 @06:31PM (#2576857) Homepage
    They are held together in the same way that magnets can stick together -- the isotope has a positive charge and the molecular cage has a negative charge.

    Magnets do not stick together because one has a positive charge and the other has a negative charge. I learned this in third grade science.
  • RMA rate? (Score:1, Funny)

    by Anonymous Coward
    Ooops, my nanorobot is malfunctioning and killing me from the inside out. Could you send a tech out? What? Monday is the earliest? I *GUESS* I could wait....
  • Thaer has to be something to this radiation therapy. Mr Burns is like 150 years old and never had cancer.
  • by Dr. Zowie ( 109983 ) <slashdot&deforest,org> on Friday November 16, 2001 @07:03PM (#2576957)

    Alpha emitters are great for this kind of work, because alpha particles have a high interaction cross section once they're inside the body. That concentrates their damage in a small space. (You can handle blocks of alpha-decay material without hazard, because the alpha particles plough into your epidermis and stop there, wreaking terrible damage on ... tissue that's already dead.)

    I bopped on over to one of the online charts of the nuclides [kaeri.re.kr] to check out the decay chain of Ac-225 [kaeri.re.kr]. Indeed, the next two daughters are alpha-emitters, but the first one, Fr-221, has a 5-minute half-life. That ought to give it plenty of time to get ducted around into your bloodstream and into the rest of your body before emitting the next two alphas and a couple of beta particles, eventually transmuting to stable Bismuth.

    So the developers aren't being quite candid when they say that the daugter alpha particles could inflict additional damage on the tumor. Sure, they could -- but (with the antibody bonds long since broken by the recoil from the initial decay) that atom could end up anywhere in your body before decaying again.

    This stuff is interesting -- I used to make radioactive saline at the Reed Reactor Facility [reed.edu] for medical uses, so I poked around the chart of the nuclides to see how one would make Ac-225. Ideally, you want to start with a nice, stable (or at least long-lived) element, kick a neutron into it (by lowering the ore into a nuclear reactor), and let it turn into what you want via a series of rapid decays. (That's one way to make the Americium 241 in smoke detectors; I'll leave the source element as an exercise for the reader). But Ac-225 doesn't seem to have any such nice precursor decay paths with short half-lives. The half-life is short enough that you wouldn't want to get it from spent fuel (too `hot' until after the Ac-225 is gone!), so I'm not entirely sure how you'd make it.

    • so I poked around the chart of the nuclides to see how one would make Ac-225[...]But Ac-225 doesn't seem to have any such nice precursor decay paths with short half-lives.

      I did a bit of web searching (with my CRC "Table of the Isotopes" handy), and it looks like the key is Uranium-233.

      U-233 can be formed in a breeder reactor from Th-232, by: Th-232 + n -> Th-233 -> Pa-233 + e- -> U-233 + e-

      Once you have the U-233, U-233 -> Th-229 + alpha -> Ra-225 + alpha -> Ac-225 + e-

      This page at ORNL [ornl.gov] indicates they have a stockpile of 400kg of Uranium-233, and are "the only significant source of bismuth-213 [3 decays down from Ac-225, also useful for cancer treatment] in the western hemisphere".
    • Didn't the article say that the isotope is attached onto an antibody? Thats how it got to the tumor int he first place, why would you think it's going to emit an alpha and just get up and leave?
      • when the alpha particle is emitted it will have a +2 charge and have high kinetic energy. As it flys through it's invironment it rips surrounding electrons from thier nuclei creating ions which no longer hold the covalent bonds in thier respective molecules and the molecule decomposes with it's charged shards flying apart.

        Incidentally this is the same process that can kill the cell by creating toxic/useless molecular (ie. DNA or protien) fragments in the alpha particle's wake.
      • It'll just get up and leave because of the recoil forces on the Francium (formerly Actinium) nucleus. (A) it won't be bound anymore because the electron orbitals will change, and the chemistry of Americium is different than the chemistry of Francium; and (B) the recoil energy is large compared to the strength of chemical bonds.
    • Francium is highly chemically reactive. I would guess that if the whole complex is taken inside the cell as opposed to hanging outside (something I'm unclear about) then it will chemically bond with something inside the cell, rather than leaving and wandering around.
  • by Chico Science ( 151552 ) on Friday November 16, 2001 @07:43PM (#2577000) Homepage
    I work at the National Cancer Institute and figured I'd give my personal scientific view (not official, since I'd get flayed for doing that).

    While the research *is* interesting there are a lot of caveats. The article specified that this technique has been successful in treating a broad range of cancers. In culture. This means there's cells in a flask with medium and they add the agent to the medium. This means the cancers are definitely coming in contact. In a human system, this may not be the case. An intravenous injection may not service tumors embedded in tissues. Especially brain tumors because of the blood-brain barrier.

    Another caveat. Nearly every system of targetted therapeutics involving antibodies has failed in humans, despite any remarkable results in mice. Several other wildly successful therapeutics in mice (angiogenesis inhibitors for example) are only modestly successful in humans.

    Models, be they mouse or cell culture, do not carry over terrifically well to 'in the wild' cancers in humans. Entirely possible that these treatments will have some benefit for certain cases. On the whole, this isn't the "smart bomb" or "cure for cancer" the media portrays. Unfortunately, the AP doesn't report the caveats. Also, as of yesterday, I wasn't able to find any reference to this study in medical literature. I suspect that the moment the journal it was submitted to accepted the paper, a publicist was on the phone with the press. Accordingly, the media story is in the hands of the public before the peer reviewed article is.

    Just another case of wait and see. I hope for the best, but don't expect it (sorry guys).

    Ciao, C.Sc.
    • Just a small quibble:

      First: the article was published in Science and is available here [sciencemag.org].

      And you're very right in pointing out that of the vast number of antibody-directed cancer therapies mentioned in the literature, almost all have failed in people. However, there are a few successes - Mylotarg, [wyeth.com] Ontak [ligand.com], Herceptin [herceptin.com], and Rituxan [gene.com] spring to mind. In fact, the Herceptin antibody was one of the antibodies used in this study - which increases the odds of clinical relevance.

    • Interesting. Of course, if every promising treatment worked, we'd all be immortal by now.

      As a college sophomore, I'm not qualified to answer your other points, but I did manage to find the full text of the article, if you're interested: http://www.sciencemag.org/cgi/content/full/294/554 6/1537
  • For those who didn't read the article, the deal is a chemical cage binding actinium-225, keyed to a certain protein. Deliver to cells, cage unlocked by matching protein strain, single actinium atom decays shooting off aplha particles, killing the offending cell and maybe a couple of its neighbors. If the "collateral damage" is managable, this may actually be a cure. A CURE for cancer. This is awesome. Its been tested both in mice, with against mousy cancer cells, and against human cancer cells in mice. There's no reason to expect that it wouldn't work in humans. This is very good news.
    • this may actually be a cure. A CURE for cancer

      Good. Now, the next time some "basic research" project like the SSC or a NASA planetary probe gets government funding, people won't be able to ask why their tax dollars are being "wasted on this %^#@$ instead of trying to find a cure for cancer" (and advances in genetically-modified foods should be able to get rid of the "... ending world hunger" one before too long too).

      [Yeah I know, but my Karma's at 50 anyway, so go ahead and take your best shot...]

      [Also, I remember reading about monoclonal antibodies in Discover or a similar publication back in the '80s. It doesn't appear to have been the miracle cure they thought it would be. Hope they have better luck making the jump from mouse to human this time]
  • "The ring holds the atom in the center like a hula hoop containing a basketball," said Scheinberg.

    Have you ever seen Micheal Jordan do that trick were he spins a basketball around inside of a hula hoop?

    No? That's because it's damn hard!

    Actually, this sounds like a nifty application of technology. Even if the device has targetting capabilities to rival the US missles that blew up the hospitals in Afghanistan (wink), it'll probably do less damage to normal cells than chemo.
  • If nanomachines are built that would actually go into the bloodstream or whatever, seek and destroy cancer cells, that would be one of the most amazing advances in human technology that will simultaneously benefit modern medicine and just about every field on Earth.

    Maybe one day, they'll invent machines that go into your body, swim around and kill things like the flu. Or perhaps drill through plaque in peoples' arteries to prevent heart attacks. Or who knows what else.

    Of course, then the military will start experimenting with nanomachines that wreak havoc on someone's body, and then it'll probably get copied by some other country, and as a result, our military will build nanomachines that seek out and destroy other nanomachines, and so will the other folks, and next thing you know, there are nanowars going on inside peoples' bodies.

    Well, what can I say? There's an advantage and disadvantage to everything. Oh well.

  • by chrisserwin ( 448761 ) on Friday November 16, 2001 @07:53PM (#2577023)
    It seems like a lot of the harmful side effects come from using actinium-225, which self-decays, not necessarily waiting until it has accumulated in it's targeted host. I wonder if they could use boron instead, which is fairly inert, and a beam of neutrons to accomplish the same task.

    Back in my college co-op days, I worked at the Idaho National Engineering Laboratory in Reactor Design. Down the hall they were doing brain tumor studies on rats treated with a technique called BNCT: Boron Neutron Capture Therapy. The theory was to inject a water soluble boron compound into the body. Water soluble molecules do not pass well through the "blood-brain barrier", therefore, will not easily pass into healthy nerve cells. They do, however, accumulate in cancer tissues. Boron is nice because it is fairly inert until it interacts with neutrons and breaks down into alpha particles and non-threatening elements. So the theory was that the Boron would accumulate in the tumors and they could then bombard the tumor with neutrons, producing an explosion of alpha radiation... no more tumor. I didn't work on this project, and I'm not sure what became of it.... I think this technique may be used in other countries.

    I think the nice thing about the current technique is the ability to target specific proteins. I wonder if a boron/neutron might have an additional advantage - unlike actinium which would decay over time (like the oven on "warm", the boron approach would be more immediate. Think "broil".
    • I wonder if they could use boron instead, which is fairly inert, and a beam of neutrons to accomplish the same task.

      Makes sense to me. I guess they started with the napalm when something more specific might be better. Probably isn't in their main line of research, so they didn't think of it. Alternatively, they wanted to start with the napalm approach from a research perspective and remove one less thing from the chain of possible failures.

    • That research you're talking about has borne fruit. BNCT is now becoming a widespread treatment option.
  • It think it is slightly premature to hail this as the cure for cancer. The problem is without a subscrition we can't even get to the Science magazine [sciencemag.org] website. I'd love to peruse the article but i think it needs registration, and the free version seems to only give abstracts. We don't have proper figures on their tests so there's no way we can individually verify what the article is saying.

    The treatment may work on mice but its no guarantee it will work on humans - major clinical trials (which take a long time) would need to be done before the public could get to a treatment. The CNN article is a bit sketchy on details, but it did point out this fact. Thalidomide is an example of treatment which worked in lab experiments but went on to cause chaos with mothers who used it (their babies were born deformed).

    Another issue is how it targets cells - it's no good if it targets healthy cells as well. However chemotherapy and radiotherapy also have this side effect so if it kills less cells and is succesful in killing the cancer cells it should be used. But as i said more information (i.e. free access to the original article) would be nice so we could make a more informed opinion on this article.
    • It think it is slightly premature to hail this as the cure for cancer. The problem is without a subscrition we can't even get to the Science magazine [sciencemag.org] website. I'd love to peruse the article but i think it needs registration, and the free version seems to only give abstracts. We don't have proper figures on their tests so there's no way we can individually verify what the article is saying.

      Just take a trip over to your library. Just about any public library worth its spit ought to have a subscription to Science. If not, trip on over to the local university library. They at least ought to have one.
  • If you get overexposed to radiation, you can form cancer. If the isotope did target the wrong cell, could it cause cancer in it, worsening the problem?
    • Yes. My SO had radioactive iodine (I131) treatement for thyroid cancer. There were big warnings about how it could cause cancer (especially lymphoma and leukemia). On the other hand, it is extremely effective at preventing recurrence, so....
  • The idea of weapon usage for this just went through my head, so I decided to post a little 'mini-article' about it (notice it is now 4 am...)
    Notice this does not mean I object to this technology, just thinking of putting in something new for discussion:

    First of all, you ask, how can this be a weapon? I am reffering to the nanotechnology robot combined with the cancer-cell-seeking-molecule. These can be built in different ways to be offensive.

    This first and interesting way would be to make the molecule act only in response to some other molecule (hormone or other) or DNA strand (although that probably won't be effective as DNA strands are not common outside the cell, and the thing doesn't enter the cell unless the binding molecule is active). This would allow this technology to be used as an ethnic weapon: discover a protein built only by 'colored people', and target it. Distribute the composure around (I think even bin Laden doesn't have enough money to make effective doses of this) and vwalla: colored people get cancer (or maybe the robot should emit cyanide molecules?)

    Advantages on this part?
    I'm not sure how well this nanotechnology is built, but it might prove a poison better-built than normal chemical poisons, and which the attacker has perfect anti-dote to.

    Why would this be used? (for crying out loud?)
    1. Weapon research in shape of 'regular' research: an underdeveloped country could get millions on millions of dollars to cure breast cancer among it's population, and use nanotechnology facilites built for it to develop weapons.
    2. To target certain targets: ethnic weapons, as said above, created by insane but powerful people to promote some twisted philosophy
    3. By mistake: normal nanotechnology 'cure' gone a bit awry attacking wrong cells, or other.

    Major points as to wether or not this is feasible:
    1. Targeting - can this 'weapon' be targeted properly? Or does it have to be injected straight into the 'target'?
    2. Power - can something like this be a real killer? how much of a 'killer droid' would be a lethal dose?
    3. Feasible as distribution: can it infiltrate the body from water? food? air/touch? can it survive days/weeks/years in operating condition? Can it exit an attacked body and attack another? (man having cells killed extracting cells with the weapon to sewage, where they go attacking again)
    4. Unavoidable - can such an 'infestation' be dealt with easily? by heating/cooling/treating with chemical/building antidote/suing the company who made them ;)

    To conclude, this technology looks great. I sincerely believe there is a 'fast-cure' for cancer (as the problem seems simple, enginerringly speaking.). This solution seems excelent.
    The discussion about using this as weapon technology existed long before this post or this usage for nanotechnology - it existed since nanotechnology and biology were combined.
    I believe in building this technology. I just wondered what others think about the possibility of this turning into a weapon

    "If it looks like a duck, quacks like a duck but takes a cab instead of walking like a duck, it's simply a snobby duck. shoot it"
  • Hopefully (Score:2, Funny)

    by c_jonescc ( 528041 )
    <I>"...researchers are testing a microscopic "smart bomb" to target, attack, and kill cancer cells."</I>

    I just hope they can tell the difference between my organs and say a Chinese Embassy, or Red Cross Center.
  • is that radiation at one level is used to kill cancer, but at another level is able to create cancer. Just felt like saying that. Thank you.

    I know I've got a sig around here somewhere...
  • The key technology behind this field of engineering is the assembler: a device that can construct structured substances an atom at a time. The assembler builds other machines capable of performing any task for which they are programmed and have the required energy source. The Nanotech engineer is an expert in designing functional structures on the atomic scale, a task requiring strong knowledge of quantum mechanics, chemistry, robotics, and mechanical engineering. He is also familiar with anal penetration techniques that methodically take apart a anus and map the location of each stinky bit. Research in this field is heavily regulated due to the extreme danger of lethal stench, and most research is performed in isolated locations such as outer space and micheal jacksons bathroom.

The world is coming to an end--save your buffers!