Soothing Music and the Bordeaux Bacterial Bouquet

17 November 2008
Presented by Ben Valsler.

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In this week's NewsFlash, we discover a new 'cure' for hayfever and why happy music could make your heart grow stronger.  Plus, the bacterial secret to the bouquet of wine - why some flavours may be down to the bugs in your mouth, and we look into pelagic politics - why some fish make natural leaders.

In this episode

Better way to battle allergy

Nose BlowWith asthma and allergy cases amongst young people at an all time high, a study from scientists in Switzerland offers a breath of fresh air. Gabriela Senti and her colleagues at University Hospital Zurich, writing in this week's PNAS, have found that injections designed to desensitise people with allergies can work much more powerfully if they are administered into a lymph node rather than under the skin.

Traditionally doctors have attmempted to damp down overzealous immune responses in people with allergies by injecting weak doses of the offending allergen into the skin. The idea of this therapy is to provoke immune tolerance towards the foreign material by pursuading the immune system to regard it as a friend rather than a foe. Unfortunately this approach has mixed results and can be dangerous because it may trigger severe anapyhlactic reactions. Consequently people with the most severe allergies, who have the most to gain from desensitisation treatments, are often unable to be treated in this way. But this approach is probably flawed because the skin is heavily primed to react to allergen exposure, rather than developing tolerance.

Instead, the Swiss team reasoned, allergens would probably be better off injected into lymph nodes where allergens are normally introduced to the immune system and where immune cells are educated. Working on this premise the researchers recruited 183 hayfever sufferers and randomly assigned them to receive either 54 desensitising injections into the skin over a 3 year period or 3 injections into a lymph node in the groin over a 3 month period. The volunteers were then followed-up for the next 3 years during which allergy symptoms, responses to skin prick tests and anti-allergy medication use were monitored.

The results were very impressive. After three years both groups showed improvements in their allergies but the patients who received the lymph-node injections, which they rated as less painful than skin injections, suffered fewer side-effects and achieved much faster improvement in their symptoms. "The enhanced safety and efficacy observed with intralymphatic therapy...could make immunotherapy more convenient, shorter and less costly," the researchers say.

Music to make your heart sing

Listening to your favourite, feel-good music might not only put you in a great mood but it could also be good for your heart. 

Researchers from the University of Maryland School of Medicine in Baltimore in the United States have shown for the first time that the emotions associated with listening to joyous music has a beneficial effect on blood vessels leading to improved blood flow, in a similar way that laughter has already been shown to be good for us. 

The study, which was presented at the Scientific Sessions of the American Heart Association in New Orleans this week, involved ten healthy volunteers who were tested with four different types of music that they were played for half an hour each at a time. The volunteers were asked to bring along music they really liked and made them feel happy and apparently most of them chose country music. They were also played music that they didn't like and made them feel anxious: most of them chose heavy metal music. Thirdly they were played music designed to be relaxing and in a fourth session they were played videotapes intended to make the volunteers laugh.  

To measure the effect of music on blood vessels, the researchers measured something called flow-mediated dilation. This essentially determines how the lining of blood cells called the endothelium responds to various different stimuli (from things like exercise and emotions) and it shows how well blood is being delivered to the tissues of the body. 

Measuring the flow-mediated dilation involves restricting blood flow briefly along an artery in the upper arm using a cuff, then releasing it and using an ultrasound to measure how the blood vessels respond to the sudden increase in blood flow. And that gives you a percentage increase or decrease in the diameter of blood vessels. 

The researchers found that when the volunteers listened to their happy music, their blood vessels expanded by around 26%. A similar, but smaller effect happened when they listened to relaxing music. The opposite happened when they were played the unhappy, anxiety-inducing music with the blood vessels constricting by around 6%. And as you might have guessed, opening up the blood vessels is for many reasons Heartsgood for us. 

And interesting point is that the effect of playing funny videos to make the volunteers laugh caused an increase of 19% in blood vessel diameter which is less than with happy music. But, we don't know whether the volunteers did actually find the tapes funny since we do all have a different sense of humour, while they did choose the music as being tracks they particularly liked. 

Researchers don't really know what is causing these effects but think it is most probably linked to the release of endorphins: those pleasure chemicals in the brain. And it isn't that country music will work for everyone, it depends on what music you like as we are, after all, all different. 

Exactly how the emotional response of listening to music affects the rest of our bodies remains something of a mystery. But it certainly suggests that it could well be good for us all to spend some of our daily lives listening to our favourite music.

Thank bacteria for the flavour of food

Swiss scientists have solved a Sauvignon conundrum this week with the discovery that part of the flavour of the famous white wine is down to bacteria in your own mouth! The French enologist Emile Peynaud drew attention to the burst of fruity flavours that follows 30 seconds or so after a gulp of the white wine is swallowed. This is known as the retroaromatic effect and similar olfactory phenomena accompany onions, peppers and other fruits and vegetables.

To find out why it happens Christian Starkenmann and his colleagues at the Swiss flavour company Firmenich collected saliva samples from volunteers. Half of each sample was sterilised by gentle heating to kill any bacteria whilst the other half remained pristine. The researchers then added odourless sulphur-containing chemicals called cysteine-S-conjugates, which are the same as those found in wine and other fulsome foods. The saliva-sulphur mixtures were then wafted beneath the noses of a second group of people. A smell was only detected when the mixtures included the pristine saliva, and lasted for between 30 seconds and 3 minutes, just like the taste of the Sauvignon.

To find out why the team cultured bacteria from the saliva samples and succeeded in growing one common anaerobic (oxygen-hating) species called Fusobacterium nucleatum. When this was added to the sulphur compounds dissolved in mineral water it released the same aromas as the intact saliva. The bugs, it turns out, can break down the odourless chemicals to produce aromatic sulphur-containing chemicals called thiols. It suggests, say the team, that this mouth bug is at least partly responsible for the way things taste and smell!

Fish choose leaders by Consensus

3 spined sticklebackWhile the world headlines are still full of the news that the Americans have elected Barrack Obama as the first African-American president there is also news this week of how members of the fish world elect their leaders. 

When it comes to deciding which leader to back, most of the time fish reach a consensus to go for the most attractive of two possible leaders. But like a stereotypical sheep following the flock, fish will also follow whatever choice most of the rest of their shoal take - whether it's the right choice or not. 

This is a study from a team of researchers led by David Sumpter of Uppsala University in Sweden and Ashley Ward of Sydney University in Australia, which they published this week in the journal Current Biology. 

They conducted experiments in aquarium tanks with little freshwater fish called three-spined sticklebacks. From previous studies the researchers knew that the fish had certain preferences for leaders; they tend to follow fish that are bigger and plumper, with fewer spots that could indicate they have a parasitic infection. In general they back the fitter more successful fish. 

But what the researchers wanted to know was whether a shoal of fish comes to a group decision on which leader to back by consensus, in other words, do they make decisions that reflect the general opinion of the group?  

A similar thing happens when people are asked to sit on a jury in court. It was an 18th century French Philosopher, Condorcet, who showed that as the size of a jury increases so does the chance that the group will correctly decide if the defendant is guilty or not. And it seems a similar thing does indeed happen with fish. 

Sumpter and Ward made replica fish that had different levels of fishy attractiveness: some were bigger and fatter, some small, skinny and spotty - and displayed various pairs of possible leader fish to groups of sticklebacks. And quite simply, the groups checked out the two possible leaders and swam towards the one they chose. 

The researchers saw that as the size of the shoal increased, the fish got better at accurately choosing the better leader, which is the one that is bigger, better fed and free from infections. 

While the consensus of the group was accurate most of the time, occasionally the shoal of fish would slip up and make the wrong decision, swimming towards the less attractive leader. 

But who can blame the sticklebacks, since sometimes us humans make the same mistakes? Even if copying what the majority of other people around us are doing isn't always the right thing to do, on the whole it tends to be a good strategy.

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