BACK in 1984, a young Australian doctor called Barry Marshall swallowed a nasty-tasting solution of bacteria. This was no accident. He did it to convince his peers that his suspicions about a highly prevalent disease were not as far-fetched as they thought.

In 1981, Marshall had met pathologist Robin Warren, who had found curved bacteria in inflamed stomach tissue. In further studies, they found that this bacterium, later named Helicobacter pylori, was present in most people who had inflammation or ulcers of the stomach or gut. Like two long-forgotten German researchers in 1875, they concluded that these bacteria were to blame.

“I was met with constant criticism that my conclusions were premature,” Marshall later wrote. “My results were disputed and disbelieved, not on the basis of science but because they simply could not be true.”

It is often claimed that doctors were wedded to the idea that ulcers were caused by excess stomach acid, or that they didn’t believe that bacteria could grow in the stomach. In fact, the main reason for the scepticism, says Richard Harvey of the Frenchay Hospital in Bristol, UK, was that four-fifths of ulcers were not in the stomach but further down the digestive tract.

Yet we now know that Marshall was right. After downing his bacterial concoction, he soon became far more

A cure for ulcersill than he had expected, vomiting and developing stomach inflammation. Later studies confirmed the theory. His discovery made it possible for millions of people to be cured of their ulcers with antibiotics, instead of having to take acid-reducing drugs every day.

It turns out that H. pylori causes ulcers by boosting acid production in the stomach. The big mystery is why, when half the world’s population carries the bug, only a small proportion develop symptoms. Harvey’s team has been studying the benefits of eliminating H. pylori, which has been shown to cause stomach cancer as well as ulcers. He has no doubts about his conclusions: “The only good Helicobacter is a dead one.” Michael Le Page

11 September 2010 | NewScientist | 39

WHEN the evidence suggested that the baffling “spongiform” brain disorders Creutzfeldt-Jakob disease (CJD), kuru and scrapie could not be transmitted by a virus or bacterium, the neurologist Stanley Prusiner put forward a novel type of infectious agent as the cause: a rogue protein. It was an idea considered so outrageous that Prusiner was ridiculed.

Prusiner first began to study these diseases in 1972, after one of his patients at the University of California, San Francisco, died of CJD. A decade later, in the journal Science (vol 216, p 136), he suggested that these diseases were caused by a “proteinaceous infectious particle”, or prion.

The idea built on the findings of British researchers. In 1967, Tikvah Alper of the Medical Research Council’s Radiopathology Unit showed that whatever it was that caused CJD was unscathed by levels of ultraviolet radiation that would destroy any genetic material (Nature, vol 214, p 764). Shortly afterwards, mathematician John Stanley Griffith of Bedford College in London devised a protein-only hypothesis for scrapie propagation. His 1967 Nature paper (vol 215, p 1043) states there was no reason to fear that the idea “would cause the whole theoretical structure of molecular biology to come tumbling down”.

This work sparked little interest when it was published. By the time Prusiner became involved, however, indifference had hardened into scepticism. In December 1986, a sardonic profile of Prusiner appeared in Discover magazine, headed “The name of the game is fame: but is it science?” Yet just 11 years later, he was awarded a Nobel prize. There are still unanswered questions about the prion model, but no one doubts that Prusiner’s work provides deeper understanding of this cause of dementia. Roger Highfield

Prions

THOUGH he didn’t realise it at the time, in 1937 the British engineer Alec Reeves laid the foundation stone of modern digital telecommunications networks. The valve (vacuum tube) was then in its heyday, digital computers were still years in the future, and the transistor a decade away.

In 1927, commercial transatlantic telephone calls were made possible by radio telephones. In the early 1930s, Reeves helped develop higher-frequency radios that could carry several calls at the same time, but these conversations interfered with each other, producing a noisy, hard-to-understand signal.

Then Reeves realised that converting these analogue representations of speech into a

Digital telecommunications

series of telegraph-like pulses might avoid the troublesome interference. He designed circuits to measure the strength of each speaker’s voice 8000 times a second and assign that signal strength to one of 32 levels. Each level was then represented by a sequence of five binary digits. As long as the receiver could tell the binary 1s from the 0s, it ought to be able to turn the stream of pulses back into interference-free speech.

That was the theory, at least. “No tools then existed that could make it economic,” he wrote more than 25 years later. His employer, ITT, patented pulse-code modulation, but never earned a penny before the patent expired in the 1950s.

Reeves was something of a visionary, often saying: “I will be right about the things that I say are going to happen, but I will never be right about when.” Perhaps he thought he really could see the future. He studied spiritualism and believed he was getting signals in Morse code from other worlds.

ITT managers eventually put him in charge of exploratory research at the Standard Telecommunications Laboratories in Harlow, Essex. In that role, he launched a group to study laser communications, and enthusiastically supported work by Charles Kao that led to the fibre-optic network that today carries pulse-code modulated light signals around the world. Jeff Hecht n

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