Health and Medicine – Page 38

Predicting Chemo Success

French researchers have identified almost 700 genes in the tumours of colorectal cancer patients
whose expression was different between patients who subsequently responded well to combined chemotherapy and patients who were resistant to the therapy. The findings could ultimately help cancer specialists decide which course of treatment for patients with colorectal cancer is most likely to work best.

Sandrine Imbeaud from the CNRS and Pierre and Marie Curie University, Villejuif, France, used microarrays to analyse the gene-expression patterns of samples from colon tumours and liver metastases collected from 13 patients with colorectal cancer. The microarray analyses were carried out before the patients were treated with combined chemotherapy of folinic acid,
5-fluorouracil and irinotecan. The team identified 679 genes that were produced differently in patients who later responded well to chemotherapy.

Details of the research were published today in the journal Genome Biology.

Killer Coral Compound

Jerry Pelletier of McGill University, in Quebec, Canada, and colleagues have discovered a small molecule (which means it could be easy to make) in coral that can inhibit the replication of certain viruses. The research shows that the natural product, known as hippuristanol, blocks the protein-production machinery in cells that is hijacked by viruses and so halts a viral invasion in its tracks.

Hippuristanol is produced by the coral Isis hippuris, hence the compound’s name and seemingly prevents the viral protein, eIF4A, from binding to messenger RNA, mRNA. mRNA carries the code to make proteins from DNA to specific sites of protein synthesis in the cell. By binding to the mRNA, eIF4A initiates the translation of the protein code. Hippuristanol prevents replication by inhibiting this process.

Viruses, such as poliovirus hijack this protein machinery and so can be blocked by hippuristanol, at least that’s the theory. Hippuristanol could soon join the growing arsenal of antiviral compounds although it is still a long way off from being added to the GPs prescription books.

You can find the complete paper in Nature Chemical Biology: http://dx.doi.org/10.1038/nchembio776

Herbal Hogwash

Why is it that in a centre of scientific and medical excellence, namely Cambridge, do the city’s powers that be think it’s a good idea to let a herbalist pedal their wares in a prominent city centre shop?

At best, the products on sale are pseudoscientific hogwash for which any positive effects are likely to be mere placebo in origin. At worst, the apothecary’s shelves are laden with unregulated, untested, and potentially toxic materials that dupe those with any of a vast range of diseases into believing in a panacea for their ills that simply does not exist.

If these products worked, wouldn’t it be an obvious sector of the market for the pharma industry to move into? Surely, that would have happened already, if these products worked…

Regional Blood Groups

A sciencebase visitor emailed today, asking whether blood types really do correlate to different areas of the world and disease resistance in those particular areas. She suggested that maybe we should be living in those areas to give us protection. At least that’s what I think she was implying…

Well, there is no short answer, but I’m sure most people would rather not have where they live dictated by the disease protection status of their blood type. If I lived in a wealthy northern european city, but happened to have a blood type that protected me against malaria as is the case with carriers of the gene for sickle cell or thalassemia, I wouldn’t want to move to a place where malaria was rife, unless I had another good reason to go.

Anyway, the straight answer to the question is that yes, certain blood types have a different risk associated with specific diseases and that in terms of ancestry these blood types tend to be associated with particular regions. As I said, it seems that being a carrier of the sickle cell gene provides some protection against malaria and the same too for thalassemia. On a related note, other “diseases” are associated with reduced risk of specific infection. Carriers of the cystic fibrosis gene (not a blood type, obviously), for instance, have a lower chance of suffering from typhoid and cholera.

Sciencebase readers might be able to shed a little more light on the relationship between blood type and disease risk.

Avian Influenza Lottery

According to a previous interviewee of mine, Sir David King (one-time UK chief advisor on science), you’ve got far more chance of winning the lottery than catching H5N1, the most-talked about of the avian influenza viruses. King told The Times that the chances of someone in Britain catching bird flu is 1 in 100 million. Compare that with the 14 million to one chance of winning the lottery and you can see just how small the risk is.

It’s essentially what we’ve been saying all along, the media generally loves a health scare, and H5N1 is just the latest of those (along with benzene in soft drinks of course). It is nevertheless only a matter of time before someone in the UK does succumb to this virus (unlocky sod), but even when they do, that does not herald the global pandemic of killer flu that the scaremongers are hoping for. I say hoping, they really will have a field day once that little bundle of genetic material and protein finds a way to carry itself from human to human…good news never sold papers, after all.

Pro Active Health and Diet

Catching up with the Sunday supplements two ads caught my eye. The first was for Flora pro.activ, which contains dairy peptides and supposedly is proven to help control blood pressure and maintain a healthy heart. The second was for Sirco, which is apparently approved by Heart UK and is supposed to “naturall” thin the blood to help improve its flow. On the same day, I read a BBC news item telling us that eating oily fish isn’t as good for us as we had been led to believe. Also in the mail that day was a reprint from by friend Bradford Frank (an MD at the University of Buffalo School of Medicine), his paper [Ann Clin Psyc, 2005, 17(4), 269-286] reviewed the various antioxidants and stacked up the evidence for which are any good at reducing the risk of developing Alzheimer’s disease. Seemingly, aged garlic extract, curcumin, melatonin, resveratrol, Gingko biloba extract, green tea, and vitamins C & E all have a strong association with a reduced risk of AD. On the other hand, acetyl-L-carnitine, alpha-lipoic acid, bacopa monniera, ferulic acid, and ginseng are only very weakly associated with any reduction in risk. Huperzine A, adds Frank, falls into a special category as this compound actually inhibits the very enzyme that AD drugs target – acetylcholinesterase (AChE).

So, what is one to make of all these various pieces of information. It seems to me that far too much effort is spent on trying to augment the healthy balanced diet we should all aspire to, but more importantly, all these various threads seem to suggest that exercise and mental activity play no role in protecting us from disease. The people who buy pro-activ and Sirco, and those who pop dozens of different antioxidants, trace elements, and vitamins might hope to live forever, but with the impending threat of emerging viral disease and nuclear terrorists, a splash of Sirco or a handful of Gingko leaves is probably not going to help.

Benzene Soda Sense

Sciencebase has just received some additional information from Sense About Sense on the benzene in soft drinks debacle. SAS, is a UK organisation that promotes an evidence-based approach to scientific issues (something that all organisation should be promoting to be honest!).

Anyway, according to their spokesman (Cambridge chemist Jonathan Goodman), one would have to drink almost a litre (800 ml) of soft drink containing five times the WHO limit to match exposure from a single car journey. This is a comparison to that made by Richard Laming of the BSDA who says that someone living in a city consumes, on average, 400 micrograms of benzene from exhaust fumes in a normal day, which is equivalent to consuming 40 litres of a soft drink containing benzene at just over the World Health Organization guideline level of 10 parts per billion.

SAS also told us that benzoate does indeed degrade to benzene, as other media reports claimed. However, either of the possible reaction pathways, while plausible, “are probably very slow.”

Benzene in the London Times

Benzene Ring UK paper the Times today picked up on the benzene in soft drinks problem I mentioned in sciencebase on February 22.

The paper reports how the Food Standards Agency has found levels of benzene (“six parts carbon, six parts hydrogen”) at eight times the level permitted in drinking water in samples from some 230 drinks on sale in Britain and France.

What’s more interesting than this finding, eight times a miniscule amount remains a miniscule amount, is that the paper lists several sources of benzene to which we might be exposed. It is, says reporter Rajeev Syal, It is produced during incomplete combustion of carbon-rich substances: “produced from petrochemicals, but occurs naturally in volcanoes, forest fires and in cigarette smoke. Volcanologists, forestry firefighters, and smokers should be listed among those banned from worrying about their being too much benzene in their cola, bottled water, or ‘fruit’ drink.

Regardless of the actual hazards involved, what’s the betting that benzene in soft drinks will displace fears of bird flu, in the UK, for at least a couple of weeks. It might just be long enough to keep the media fed until all those ducks have flown the coop, as it were…

You can read The Times’ article (here).

Stroke Immunity

Proteins involved in the inflammatory response could be used to help in brain
regeneration following cerebral stroke, according to Swedish researchers writing in the EMBO
Journal today.

Complement proteins participate in the inflammatory response and scientists have suggested that under abnormal circumstances, following stroke for instance, their role in inflammation could contribute to tissue damage in the brain. This new research, by Marcela Pekna and colleagues of the Sahlgrenska Academy at Goeteborg University, reveals surprisingly that complement proteins may also have a beneficial role.

Pekna’s team have shown for the first time that neural stem cells and neural precursor cells express receptors for complement proteins and that the complement system positively regulates the maturation of neural cells in adult mice both under normal circumstances and during brain
regeneration after a stroke. A better understanding of the dual role of the complement system in stroke, and possibly other central nervous system (CNS) pathologies, may help researchers to design more effective therapeutic strategies by developing complement inhibitory agents that
neutralize the adverse aspects of complement activation while enhancing those that are neuroprotective and facilitate repair.

The paper is available online at http://dx.doi.org/10.1038/sj.emboj.10974

Benzene Soda

Sodium benzoate (E211) is a public health issue that has been bubbling for fifteen years and could soon come to a head and have the fizzy drinks industry frothing at the mouth.

Sodium benzoate is a preservative added to carbonated beverages, but those drinks that also have added citric or ascorbic acid (vitamin C, E300) can be susceptible to the formation of benzene as a degradation product. At least that’s the theory.

The US Food & Drugs Administration (FDA) was aware of this issue in the 1990s and alerted manufacturers who were then meant to introduce a “quick fix” to prevent this carcinogenic degradant from forming in amounts above safety levels. However, there have been hundreds of new susceptible beverages brought to market the world over since by smaller manufacturers as well as the well-known ones and seemingly the benzene message has been lost in the intervening time.

Germany’s food watchdog, BfR, and the UK’s Food Standards Agency are currently testing drinks to see whether benzene levels are above WHO recommendations. Other countries are also on the alert. The renewed concern follows the FDA’s re-opening of an investigation, closed for 15 years, into benzene in soft drinks.

You can read more details of this at industry newsletter Beverage Daily

Some studies have shown that levels of benzene are present at five times the WHO’s limit for drinking water contamination and can occur in bottled soft drinks exposed to heat and light especially.

In acid conditions, benzoate is converted to benzoic acid (the active antimicrobial form, benzoate is added as a preservative for a reason after all) and it is thought that it interacts with hydroxyl radicals released by the ascorbic acid (better known as vitamin C) reaction with iron or copper ions in the water. These hydroxyl can decarboxylate benzoic acid, releasing carbon dioxide and leaving benzene behind. But, at what rates this occurs is not clear.

Moreover, leaving out the ascorbic or citric acid from soft drinks would be the simple solution and avoiding benzoate as a preservative in foods that contain these acids naturally would offer an end to the “problem”.

However, the issue brings to the fore once again the issue of acceptable risk. Sodium benzoate is present in soft drinks only in very small amounts and even if degradation were complete, the risk to someone drinking it is tiny. To have the same exposure as lab animals used to demonstrate carcinogenicity would mean a person having to drink 10,000 bottles of benzoate-containing soda.

Still, such minor details will not stop the media from jumping on this as the next big scare story despite the fact that it’s been around for years as public chemophobia.