Wednesday 5 August 2009
Saturday 11 July 2009
The golden age of antibiotics is drawing gradually but definitively to an end.
Since Alexander Flemming revoloutionised the way we view diseases with his discovery of penicillin in 1928, we have stopped worryingabout ailments like whooping cough and tuberculosis. It's worth remembering though that pre-1920s these kind of bacterial infections were rife, and wiped out large numbers of people, regularly. Plague epidemics, for example, have occurred several times in the last ten thousand years, with notably widespread outbreaks in the mid 1300s, 1665 ('the great plague of London') and again just before the beginning of the 20th century. There were also localised bouts constantly happening all over the world up until Flemmings' breakthrough.
So we've seemed to have the upper hand on bacteria for the last 100 years or so - but bugs that we can't beat are coming back. For instance, MRSA [1] has been thwarting the efforts of hospital staff to disinfect-it-out-of-existence for a number of years now. Although they're not bactrial (but rather viral) in nature, the SARS [2] and swine flu epidemics are two other examples - rather more immediate and frightening ones - of why we need to sit up and start thinking about whether we are too comfortable with the ways we treat disease.
The problem is that bacteria are very quick to develop resistance to antibiotics. Drugs like penicillin, great 40 or so years ago, quickly became no good at treating a whole host of bacterial infections. So called wide-spectrum antibiotics have been a big problem; they act upon just about any bacteria they meet, so even if all the bacteria which are the source of the problem are destroyed, lots of others will inevitably remain which have had a chance to build up resistance. Up until now we've had reserve drugs, which we only use in emegencies, so bacteria don't have a chnace to develop resistence. Even these though, are beginning to become less effective. It may only be a matter of decades before we no longer have a last line of antibiotic defence. We need new drugs, and quickly.
In science, researchers often look to nature for inspiration, and for this reason it turns out that the majority of the antibiotics in clinical use today are what are called 'natural products'. These are complicated chemicals which float around in all living organisms. Especially interesting ones can be found in single-celled organisms. Typically scientists take one of these cells, (a type known as streptomyces is very popular) and extract some of its bodily fluids and try and identify the various compounds contained in them. This kind of process led to the identification of some of the most powerful antibiotics we know of, such as Vancomycin and Chloramphenicol.
Take for example the european Beewolf. Not a bee at all, but an insect which paralyses bees and transports them back, alive, to their sand-burrow nests. There, the imobilised bees are a welcome food source for little beewolf larvae.
The Beewolf - not a bee
The hot sandy burrows are warm and moist - perfect conditions for all types of life, including bacteria. So how is it that the beewolf larvae do so well, apparently immune to the presence of the microorganisms? Researchers have now found that the mature Beewolves smear a sticky white broth containing a previously unencountered type of Streptomyces bacteria all over the cocoons of the developing larvae [4]. The insects and the streptomyces live in a symbiant relationship - the bacteria keep the larvae safe by fighting off infections with their antibiotics, and in return they live off a diet of nice, juicy Bee. Scientists don't yet know what the active compounds the bacteria produce are, but they could prove to be potent antibacterials for human use, too.
Another symbiant partnership exists between leafcutter ants and the common fungus they feed on. The ants carefully farm the fungus, which they use as food. In many parts of the world a highly competitive fungus called Escovopsis out-competes it's fungal enemies. This never happens in ant-farmed funus patches though - why? Again, scientists have been on the trail and have found the ants have been growing bacteria alongside the fungus.
When these new-to-science bacteria were grown in a laboratory, scientists identified a new compound - dentigerumycin - and sure enough, when applied to some Escovopsis it was a potent fungicide.
There are lots more symbiotic insect-microorganism relationships out there which we haven't yet discovered. I'm not suggesting we start coating our young in sticky bacterial broths, but if we continue studying these relationships closely it is easy to imagine a whole host of potential new drugs waiting to be harvested. Then we can keep one step ahead of those pesky mutating bacteria.
Notes and references
[1] MRSA = Methicllin-resistant staphylococcus aureus
[2] SARS = Severe, acute respiratory syndrome
[3] H. B. Bode, Angew. Chem. Int. Ed., 2009, 48, 2 - 5.
[4] M. Kaltenpoth, W. Gttler, G. Herzner, E. Strohm, Curr. Biol. 2005, 15, 475 – 479
Sunday 5 July 2009
Homeopathy
Last week it was climate change, this week alternative medicines threatening developing countries. Is it me, or is benchtwentyone developing a sentimental side?
I sincerely hope not. None the less I think it's important people know a little bit about homeopathy and how dangerous it can be if approached from a naive standpoint. Homeopathy is a form of alternative medicine which claims to be able to treat various illness by presenting the patient with highly dilute 'preparations'. Sometimes the disease-causing item itself is used in the preparation, sometimes not. The important criterion for homeopathic preparations is that the substance used in them causes the symptoms the patient presents - whether it is the real cause or not is irrelevant. For example to treat a runny nose (caused by a virus, say) a homeopath might employ onion essence, as this induces the same symptoms.
And what do I mean by highly dilute? Well, for a patient suffering from hayfever, the homeopathic practitioner might take a grain of pollen and dilute it in 100 ml of water. He would then take a drop of this and dilute it again with a further 100 ml of water. If he repeats this action 30 times he ends up with what homeopaths call a 30C preparation, which would be administered to the patient. The general idea is that by presenting the sufferer with an extremely small amount of a substance which causes their symptoms, they will some how become acclimatised to it.
You might be thinking this seems a little rubbish. Would onion extract really cure me of my cold? Well, benchtwentyone (and many others around the globe) is here to point out that these astute individuals are 100% right. Once you have carried out dilution to that extent, you end up with essentially a jar of water. In point of fact, the chance of there being even a single molecule of the active ingredient in a 30C preparation is less than the chance of winning the lottery five weeks in a row [1].
When charged with this fact, homeopaths sometimes respond by stating that water has a 'memory' which somehow transfers an impression of the active ingredient (what little there is of it) to the body. I don't want to skirt the issue on benchtwentyone, so let's be frank - this is utterly unsubstantiated nonsense. Water doesn't have a memory, and once a substance is taken out of it there is no impression left on the water molecules. No serious scientist has ever presented a shred of evidence that anything like this is possible
So homeopathy is scientifically on very dodgy ground. If we are rating this treatment by how sure we are that it works based on pharmacological trials and scientific proof it scores a rather fat zero. In a recent report by premier medical journal The Lancet, researchers found that there is absolutely no evidence that homeopathy works at all on a biological basis [2].
It seems clear that in cases where homeopathy appears to do some good in patients (and believe it or not there are some patients who claim it does) it is merely a placebo effect. That is, the patient believes that they have been given a cure or treatment and thus something in their mentality makes them feel better even though there is no physiological change.
A group of scientists from the VoYS (Voice of young science) wrote to the World Health Organisation last week calling for them to issue a strong statement to condemn homeopathy as the fraudulent and dangerous thing it really is. You can read the letter, which was reported on in the guardian, here. Hopefully this will signify the begining of the end for homeopathy clinics in the developing world.
References
Wednesday 24 June 2009
Monday 25 May 2009
I was reading last week in Hugh Fearnley-Whittingstall's delightful food column that asparagus is in season again. I really enjoy this whole eating in-season produce and being eco-responsible lark (despite it being so fashionable it almost makes you cringe). It's great; you get to eat really fresh food which is also quite cheap, since there's loads of it around.
Asparagus stalks in the wild
Figure 1
Methyl mercaptan (the guilty party derrived from asparagus) and ethane dithiol are both sulfurous compounds which smell awful; like rotten eggs. Acetophenone has a relatively small methyl group compared to benzophenone which is much larger. They both smell similar though - people tend to describe the odour as a lot like burnt almonds.
[2] T. Koga etal., Infection and Immunity, 2000, 68 (12), 6912-6916.
[3] M. Lison, S. H. Blondheim and R. N. Melmed, British Medical Journal, 1980, 281, 20 - 27.
Friday 1 May 2009
Monday 27 April 2009
Histamine - the cause of our collective misery
Histamine is an important chemical in our bodies. It regulates sleep to some degree (which is why when you take antihistamines the boxes always warns you not to use heavy machinery afterwards - there's a small chance you could fall asleep) and has been shown to be released during sex too. Great.
Unfortuantely for us snivellers, it has a much more obvious role which is to act as an inflammatory agent. In principle this is good as when something horrid gets into our bodies we generally need to have our noses run (so that all the bad stuff, er, flows out) and our blood vessels inflammed (so that more blood carrying bug-eating cells get to the danger zone).
It's just a shame for me and my fellow sufferers that our bodies have declared war on ice creams in the park, wimbledon, a sunday afternoon stroll by the river and genereally anything else that involes being vaguely near grass during the summer months.
Since I was a boy I have been dosed up to the eyeballs from the end of April 'til arond September with prescription antihistamine medicines. I then switched Pfizer's expensive wonder cure Benadryl (mainly captivated by the adverts involving SWAT teams in helicopters swooping to the rescue of an atishooing sufferer). I've now cottoned on that a cheap antihistamine plus some decongestants will get rid of most of my symptoms. This does still add up however.
I've now received in the post what I dub 'the hayfever machine' which claims to be able to relieve the horrors of this condition using nothing more than a red light bulb. Of course there is the slight issue that in order to use it you have to sacrifice any iota of cool you may have (in my situation as a PhD Chemist this is more or less irrelevant, but still there is a duty to report, I feel) and cram two bulb-encasing prongs into your nostrils. These two prongs have red LEDs on their ends. You sit, uncomfortably, for three minutes, up to four times a day with these fellows in your nose and the light pouring in. The manufacturers claim it's 'safe, quick and easy to use and some sufferers will notice an improvement after just a few treatments'.
I sacrifice my last iota of 'cool'
Is there any evidence that this contraption works? One study I peroused (1) stated that after following the recommended course of treatment with the machine 72% of subjects felt their symptoms had been reduced and the study coordinators even went to the lengths of conducting an endoscopy (that is, sticking a miniture camera up the patients noses) and managed to confirm pictorially that this was the case for 70% of them.
How does this treatment work? In two ways apparently and by emmitting light of two different wavelengths. One wavelength of around 635 nanometers interacts with a light-absorbing chromophore (see article on Rhodopsin) in the white blood cells which causes a complex biological cascade of reactions which have been found to stabilise the cells and reduce histamine release. The second wavelength induces a dilation of nasal blood vessels which helps bring our bodies back to their resting state (2, 3).
I'll be reporting my degree of hayfever-induced misery on benchtwentyone as I begin using the device and we'll soon see if there's any truth in these claims.
Roll on summer.
References
(1) I. Neuman and Y. Finkelstein, Narrow-band red light phototherapy in perrenial allergic rhinits and nasal polyposis, Ann. Allergy Asthma Immunol., April 1997, 78, (4), 399 - 406.
(2) E. N. Goncharenko et. al., Bull. Exp. Bio. Medicine, effect of middle wave ultra violet and red light on degranulation peritonial mast cells in rats, 2006, 129, (4), 357 - 358.
(3) http://www.lazrpulsr.com/files/How_does_light_therapy_work.htm