**************
A world of resistant bacteria
Antibiotic resistant bacteria are becoming increasingly more commonplace. Most pathogenic bacteria are resistant to one or more antibiotics. There is the real danger of many pathogenic bacteria developing resistance to even the most recent antibiotics, and this would mean that treatment for infections we consider commonplace would no longer be easy. Often, the resistance is due to improper use of the antibiotics (not completing a course is a common cause), since even if a couple of bacteria mutate to accommodate the antibiotic, soon they dominate their systems. But one never thinks of soil as a source for resistance. Yet, only a miniscule fraction of all bacteria are harmful, and there are thousands of species that don’t harm us, but are there every where. Some researchers went about and isolated 480 different species of soil bacteria (mostly harmless to humans), and analyzed if they were resistant to any antibiotics. What they found surprised them. Nearly 25% of the bacteria were resistant to seven antibiotics, another 20% were resistant to eight, and almost all of them were resistant to more than 2 antibiotics. Many usual suspects like tetracycline and ciprofloxacin were useless against many of these bacteria. Some were even resistant to vancomycin (one of the “gold standard” antibiotics). It didn’t matter if the antibiotic was of synthetic or natural origin (one would assume greater resistance to natural origin antibiotics, due to greater exposure to these). This clearly shows that the level of resistance to antibiotics in the environment is much higher than suspected. The authors suggest new ways to study antibiotic resistance, new approaches to make new antibiotics, and combination therapeutics.
Science 20 January 2006:Vol. 311. no. 5759, pp. 374 – 377
**************
A mammoth task
Understanding extinct species has been a challenge, because most of the information is restricted to fossil remains. But genome sequencing of these species do reveal tremendous amounts of information. The problem remains that most fossils are poorly preserved, with most of the DNA lost, oxidized or fragmented, with the additional fact that extracted DNA will have huge amounts of bacterial, fungal or human contamination (it’s from the soil after all). However, fossils from “permafrost” regions can be very well preserved because of the extremely low temperatures. Researchers found some mammoth fossils in permafrost, and managed to extract DNA from them and then sequence the genome. Their studies clearly show that elephants diverged from mammoths around 5 million years ago. But more importantly, they’re one of the first to complete the genome sequencing of a long extinct species, and might be pioneers in the field of paleogenomics. Our understanding of long dead species, and their evolution in to modern ones, might just take off.
Science 20 January 2006: 392-394.
***************
Reducing chemotoxicity
One of the big problems with cancer chemotherapy is the massive death of non-cancer cells in the treatment process. This nasty “side effect” often devastates many surviving patients. The problem is that most drugs also reach many other cells on their way to the cancer cells. Much of this problem would be abated if the drug could be directly delivered to the cancer itself, but specificity has been the bane of the industry for a long time. Some breast cancer researchers tried something different. The mammary gland provides a different route for tumor access, since the mammary duct network terminates in the nipple. So these researchers directly injected chemotherapeutic drugs in to the mammary ducts (they tested this in mice). Their results were more than encouraging. Though the effectiveness of the drugs administered this way were similar to traditional IV administration, the toxicity seen was substantially less. This is extremely promising initial work (though there are differences in the mammary system of mice and humans, and so much work needs to be done) in at least the breast cancer field.
Cancer Res. 66, in press (2006)
***************
Ethanol, energy and environmental goals
Ethanol is increasingly being promoted as a viable, renewable “biofuel”, with greater amounts of ethanol being blended with petroleum. But important questions need to be asked before this. Is this process “energy positive” or “energy negative”? Does ethanol take more energy (read petroleum) to produce than it saves when being blended with petrol? After all, though ethanol is produced from crops (and is renewable), energy must go in to make it (remember the law of conservation of energy?). So, is it really a viable long term option? Some researchers have gone ahead and looked in to this (in an article I just finished reading). Here, researchers rigorously estimate the energy and environmental costs of ethanol produced from corn (the biggest source in the Americas). They compare different methods used to estimate energy costs from ethanol. A couple of earlier studies had suggested that ethanol production is actually energy negative. However, these researchers show that these two studies incorrectly assumed that ethanol coproducts should not be credited with any of the input energy. Their rigorous study concludes that current methods of ethanol production result in only about 5-25% of the energy being renewable (the rest being petroleum or gas). In addition, the greenhouse gas emission differences (benefits) were small, and not substantial. However, using new technologies and practices, such as sustainable agriculture and cellulosic ethanol production substantially improved both net energy efficiency and emissions. Clearly, this needs to be kept in mind, while planning to expand on the biofuels industry, and can result in greater energy security for a country when planned and understood right.
Science 27 January 2006:Vol. 311. no. 5760, pp. 506 – 508
********
That's it for this edition of Everything scientific, which will be back again in a few weeks, with more scientific goodies.
5 comments:
Regarding chemotoxicity, one point worth mentioning is about why non-cancer cells are also killed. I believe this is because the anti-cancer drugs are targeted toward tumour cells that are fast-replicating. So at the same time, these drugs also affect naturally fast-multiplying cells in the body. Usual suspects include hair cells (falling of hair) and intestinal cells (diarrhea).
Hi Sunil
Excellent post - I always look forward to these.
First: "Apologies for not blogging much over the past (very busy) week." - What are you doing that is more important that blogging - your thesis?
Second: The part about the energy efficiency of ethanol is very interesting. It seems very low indeed. But I believe you are incorrect when you say most ethanol is in Americas is made from corn. Most in South America is made from sugar cane and Brazil produces much more ethanol than does the U.S.
Obviously, if it takes a barrel of oil to make the equivalent of a barrel of ethanol, there is no point. But if you can fertilize the crops with something that you could not put in a gas tank, then the energy equivalence is unimportant. For example, if you could grow your sugar cane only using coal - which is abundant and not useful for propelling an automobile - then it might still be worthwhile, (it would depend on the costs).
If there were no subsidizes for ethanol, then we would know for sure if it were worthwhile to produce it: the market would just go ahead and produce it if its worthwhile.
Nice roundup. Do you know if the permafrost only became accessible for fossil retrieval in recent times, and if it was due to global warming which, I read in one report, has begun to cause the thaw of permafrost in arctic regions thus making it accessible?
Anonymous........that's a good point you bring up. Typically, cancerous cells are rapidly proliferating. Anti-cancer drugs usually target rapid proliferation (since drugs for specific protein targets in cancers are hard to come by), so because of this the anti-cancer drug also gets any proliferating cell in the body. Hair cells are amongst the most rapidly proliferating cells. Some other cells that are commonly affected are those involved in taste and smell. And there are many many more. So, the drug ends up killing them. This approach mentioned here is nice, because the restrict the reach of the drug, and minimize side effects. So here they aren't spending millions in finding new drugs that wont hurt other cells.
Michael..........hehe..i wish it were all thesis work. Well....it'll be a few months before i defend (i'm hoping its only a few).....i need to finish the project i'm working on, and science leaves so many variables that it's hard to put an exact date on it. But yes..i was caught up in labwork, and some presentations i had to make.
Yes.....the energy efficiency method is very interesting. And you're right.....a bulk of south american ethanol (especially Brazil) is from sugarcane. Brazil has actually been extremely successful in using ethanol as a fuel for automobiles. But you're right.......energy equivalence is somewhat unimportant if it cant be put in to a gas tank. The thing however is that many products from these "things that cant be put in to a gas tank" are actually useful directly. So, while taking things in to account, it's important to rigorously analyze the data. And farming itself is very energy intensive (tractors run on fuels, water pumps do, sowing is energy intensive, and making the ethanol itself is energy intensive), so after all this, the energy gained should be greater than that gone in.
Of course you have a market solution for it..........and that might work, except that there are too many examples of inefficient technology being patronized due to bad public policy, and that's hard to change.
Gawker.....actually,......there is that hypothesis, but it's hard to prove because of the disconnect between cause and effect. It might be true, but it might also be true that the technology used in finding and excavating fossils in permafrost has improved. And here, it was improved DNA extraction and separation that made this sequencing possible. Too many variables to make a definitive claim.
I like a game which needs to use flyff penya, when you do not have flyff money, you must borrow flyff gold from friends, or you buy flyff penya. If you get cheap penya, you can continue this game.
Post a Comment