Category: New drugs & treatments

Scientists engineer suicide bomber bacteria to kill other bacteria

By Ed Yong | August 16, 2011 9:00 am

In a lab in Singapore, scientists are designing and breeding suicide bombers. If their efforts pan out, they will be applauded rather than jailed, for their targets are neither humans nor buildings. They’re bacteria.

Nazanin Saeidi and Choon Kit Wong have found a new way of killing Pseudomonas aeruginosa, an opportunistic species that thrives wherever humans are weak. It commonly infects hospital patients whose immune systems have taken a hit. It targets any tissue it can get a foothold on – lungs, bladders, guts – and it often causes fatal infections. To seek and destroy this threat, Saiedi and Wong have used the common lab bacterium Escherichia coli as a sacrificial pawn.

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Evidence that placebos could work even if you tell people they’re taking placebos

By Ed Yong | December 22, 2010 4:28 pm

Placebo

In many medical studies, even people who take “fake” treatments, such as sugar pills with no active ingredients, can still feel better. These are the puzzling “placebo effects”. They are common, diverse and powerful and they raise an interesting ethical question – can doctors justifiably prescribe placebos to their patients? The standard answer is no. Doing so patronises the patient, undermines their trust, and violates the principles of informed consent. It compromises the relationship between doctor and patient. At worst, it could do harm.

But many of these arguments are based on the idea that placebo effects depend on belief; people must expect that treatments will work in order to experience any benefits. For a doctor to prescribe a placebo, they’d need to deceive. But according to Ted Kaptchuk from Harvard Medical School, deception may not be necessary. In a clinical trial, he found that patients with irritable bowel syndrome (IBS) felt that their symptoms improved when they took placebo pills, even if they were told that the pills were inactive.

Fabrizio Benedetti, a placebo researcher at Turin Medical School who wasn’t involved in the study, says, “Although several studies suggested that placebos can be equally effective without deception, this is the first rigorous study that provides scientific evidence for this.”

Referring to an earlier study published in the British Medical Journal, he says, “We did the study because we knew that physicians were giving placebo to patients secretly without informed consent. Our study was designed to test whether placebo effects could be harnessed without this secret deception.”

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MORE ABOUT: deception, placebo

Gene therapy saves patient from lifetime of blood transfusions

By Ed Yong | September 15, 2010 1:00 pm

Gene_therapyThe patient known as P2 is just 18 years old, but he has been receiving monthly blood transfusions since the age of 3. P2 has a genetic disorder called beta-thalassaemia. Thanks to a double whammy of faulty genes, he can’t produce working versions of haemoglobin, the protein that allows red blood cells to carry oxygen around the body. Regular transfusions were the only things that kept him alive but for the last 21 months, he hasn’t needed them.

An international team of scientists have managed to partially correct his genetic faults, granting him his independence. It’s a major victory for gene therapy, the act of editing faulty genes within living cells in order to treat diseases.

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Sniff-detector allows paralysed people to write messages, surf the net and drive a wheelchair

By Ed Yong | July 26, 2010 3:00 pm

In Israel’s Loewenstein Rehabilitation Hospital, the patient known as LI1 is a prisoner of her own body. She is a 51-year-old woman who was paralysed by a stroke several months ago. Suffering from “locked-in syndrome”, she is completely aware but unable to move or speak. She cannot even control the blinks of her eyes. And yet LI1 has recently been able answer questions from her doctors and communicate with her family through written messages. All she has to do is sniff.

LI1 uses a ‘sniff controller’, an incredible new technology that allows paralysed patients to control machines with their noses. It’s the brainchild of Anton Plotkin and Lee Sela at the Weizmann Institute of Science. Whenever a patient sniffs, the device measures the change in pressure inside their noses. It converts these into electrical signals that are passed to a computer via a simple USB connection. With just a sniff, people can move a cursor on a screen, allowing locked-in patients to write messages. Quadriplegics can even use the device to surf the web, or drive a wheelchair.

This technology was developed almost by accident in the lab of Noam Sobel, who studies the way of brains process our sense of smell. The group use a device called an olfactometer, which produces waves of smell to see how sensitive a person’s senses are. For one of their experiments, the team rigged the olfactometer so that volunteers triggered the odour pulse themselves when they sniffed. “We noticed that sniffs are a very good and fast trigger,” says Sobel. “It then simply dawned on us that instead of triggering odor, we could trigger anything: letters in a text writer or turns of a wheelchair.  The rest just flowed (or rather, rushed) from there.” It’s a fantastic example of the useful and unpredictable roads that basic scientific research can lead to.

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Fighting bacteria with bacteria – common nose germ provides new weapon against superbugs

By Ed Yong | May 19, 2010 1:00 pm

Staph

Our bodies are under siege, constantly fighting back assaults from disease-causing bacteria. But we are also home to many harmless bacterial species that are share our bodies to no ill effects. Now, it seems that these ‘commensals’ could be our hidden allies against their harmful cousins. In one such ally, a group of scientists has just discovered a potential new weapon against Staphylococcus aureus.

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First ever molecule that protects against ricin

By Ed Yong | April 15, 2010 12:00 pm

Ricin_castor_beansIn 1978, Bulgarian dissident Georgi Markov was walking across Waterloo Bridge in London when he felt a sharp stinging pain in his leg. A passer-by had jabbed him with the tip of an umbrella and, having apologised, the two parted ways. Three days later, Markov was dead. The umbrella had fired a small poisoned pellet into his leg, turning Markov into the most famous victim of one of the world’s deadliest poisons – ricin.

Ricin is a great example to cite to people who think that “natural” equates to “healthy”. It’s a protein that comes from the castor bean, which is easy to grow, used in a wide variety of products, and delivers large amounts of its lethal chemical payload. One milligram can be lethal, and there is no known antidote. All of these qualities make it a potential bioterror weapon, and they have galvanised the quest for an antidote. That quest has just taken a big step forward, for Bahne Stechmann at the Curie Institute has discovered the first small molecule that protects mice against ricin.

Stechmann’s drug, known as Retro-2, not only saves mice from death by ricin, it also defends them against a related class of poisons called Shiga-like toxins. These are produced by disease-causing strains of the gut bacterium Escherichia coli and while less toxic than ricin, they can also be fatal. So Stechmann’s new discovery is a two-for-one defensive deal.

Both ricin and Shiga-like toxins have similar structures. One half of each protein – the A subunit – does the killing. It irreversibly breaks ribosomes, the factories that cells use to produce new proteins. A single ricin protein can knock out 1,500 of these factories every minute and without the ability to create new proteins, our cells perish. But a weapon is useless if it can’t be fired in the right place.

Getting the A subunit into range of the ribosomes is the job of the other half of the protein – the B subunit. It’s a backstage pass that sticks to docking molecules on the surface of our cells and allows the entire protein to be smuggled inside. Once there, it gets shuttled from one structure to another until it reaches the endoplasmic reticulum, where ribosomes live. If you block this chain of transport, you neutralise ricin and Shiga-like toxins; after all, the proteins cannot destroy what they cannot reach. And that’s exactly what Stechmann’s team has managed to do.

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Treating tinnitus with an individually tailored piece of music

By Ed Yong | December 29, 2009 9:30 am

Many of us have just spent the Christmas season with a persistent and irritating ringing noise in our ears. But now that the relatives have gone home for the year, it’s worth remembering that a large proportion of the population suffers from a more persistent ringing sensation – tinnitus. It happens in the absence of noise, it’s one of the most common symptoms of hearing disorders, and it’s loud enough to affect the quality of life of around 1-3% of the population. 

There have been many suggested treatments but none of them have become firmly established and most simply try to help people manage or cope with their symptom. Now, Hidehiko Okamoto from Westfalian Wilhelms University has developed a simple, cheap and enjoyable way of reducing the severity of the ringing sound. The treatment has showed some promise in early trials and even better, it is personally tailored to individual patients. 

The method is simple. Find out the main frequency of the ringing sound that the patient hears – this becomes the target. Ask the patient to select their favourite piece of music and digitally cut out the frequencies one octave on either side of this target. Get the patient to listen to this “notched” piece of music every day. Lather, rinse and repeat for a year.

Okamoto tried this technique in a small double-blind trial of 23 people, eight of whom were randomly selected to receive the right treatment. Another eight listened to a piece of music that had a random set of frequencies cut out of it, while seven were just monitored. The treatment seemed to work. After a year, the treatment group felt that their ringing sensation was around 30% quieter, while the other two groups showed no improvements.

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MORE ABOUT: Music, notched, tinnitus

Retrocyclins: a defence against HIV, reawakened after 7 million years

By Ed Yong | April 29, 2009 8:30 am

Blogging on Peer-Reviewed ResearchHIV is an elusive adversary. The virus is so good at fooling the immune system that the quest for an HIV vaccine, or even a countermeasure to resist infections, has spanned two fruitless decades. But maybe a defence has been lurking in our genomes all this time.

Nitya Venkataraman from the University of Central Florida has managed to reawaken a guardian gene that has been lying dormant in our genomes for 7 million years. These genes, known as retrocyclins, protect monkeys from HIV-like viruses. The hope is that by rousing them from their slumber, they could do the same for us. The technique is several safety tests and clinical trials away from actual use, but it’s promising nonetheless.

Retrocyclins are the only circular proteins in our bodies, and are formed from a ring of 18 amino acids. They belong to a group of proteins called defensins that, as their name suggests, defend the body against bacteria, viruses, fungi and other foreign invaders. There are three types: alpha-, beta- and theta-defensins. The last group is the one that retrocyclins belong to. They were the last to be discovered, and have only been found in the white blood cells of macaques, baboons and orang-utans.

In previous experiments, Venkataraman’s group, led by Alexander Cole, showed that retrocyclins were remarkably good at protecting cells from HIV infections. They are molecular bouncers that stop the virus from infiltrating a host cell. The trouble is that in humans, the genes that produce retrocyclins don’t work. Over the course of human evolution, these genes developed a mutation that forces the protein-producing machinery of our cells to stop early. The result is an abridged and useless retrocyclin.

But aside from this lone crippling mutation, the genes are intact and 90% identical to the monkey versions. Now, Venkataraman has awakened them. She found two ways to fix the fault in human white blood cells, one involving gene transfer and the other using a simple antibiotic. Either way, she restored the cells’ ability to manufacture the protective proteins. And the resurrected retrocyclins did their job well – they stopped HIV from infecting a variety of human immune cells.

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MORE ABOUT: defence, HIV, retrocyclin

Drugs and stimulating environments reverse memory loss in brain-damaged mice

By Ed Yong | January 18, 2009 8:56 am

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You swallow the pill. As it works its way through your digestive system, it slowly releases its chemical payload, which travels through your bloodstream to your brain. A biochemical chain reaction begins. Old disused nerve cells spring into action and form new connections with each other. And amazingly, lost memories start to flood back.

Dementia results in massive neuron loss, but that doesn't mean memories are destroyed.The idea of a pill for memory loss sounds like pure science-fiction. But scientists from the Massachussetts Institute for Technology have taken a first important step to making it a reality, at least for mice.

Andre Fischer and colleagues managed to restore lost memories of brain-damaged mice by using a group of drugs called HDAC inhibitors, or by simply putting them in interesting surroundings.

They used a special breed of mouse, engineered to duplicate the symptoms of brain diseases that afflict humans, such as Alzheimer’s. The mice go about their lives normally, but if they are given the drug doxycycline, their brains begin to atrophy. The drug switches on a gene called p25 implicated in various neurodegenerative diseases, which triggers a massive loss of nerve cells. The affected become unable to learn simple tasks and lose long-term memories of tasks they had been trained in some weeks earlier.

Fischer moved some of the brain-damaged mice from their usual Spartan cages, to more interesting accommodation. Their new cages were small adventure playgrounds, replete with climbing frames, tunnels and running wheels, together with plentiful food and water. In their new stimulating environments, the mice returned to their normal selves. Their ability to learn improved considerably, and amazingly, seemingly lost memories were resurrected.

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Sneaking medicines past the brain's defences

By Ed Yong | January 16, 2009 8:29 am

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Blogging on Peer-Reviewed ResearchUsing genetic engineering, a group of scientists have developed a way of sneaking a virus past the brain’s defences. Don’t panic – this isn’t some nightmare scenario. It could be the first step to curing a huge number of brain diseases.

The blood brain barrier controls the import of molecules into the brain with the tight security of airport immigration.The brain seems incredibly well protected amid its shell of bone and cushioning fluid. But even the strongest of forts needs supply lines, and brain is no exception.

A dense network of blood vessels carries vital oxygen to its cells. These vessels are a potential vulnerable spot, providing access for bacteria and other disease-causing organisms to migrate in from other body parts.

But even these weak spots are heavily guarded. The blood vessels in the brain are lined with a tightly packed layer of cells that restrict the flow of molecules from blood to brain. These cells form a protective shield called the blood-brain barrier, or BBB.

It is a superb defence but it can do its job too well. Not only does it block out dangerous microbes, but it can also exclude large proteins and drugs designed to treat brain diseases. Usually, these large molecules need to be distributed throughout the entire brain to be effective. With the BBB in the way, they don’t stand a chance. Now, Brian Spencer and Inder Verma from the Salk Institute of Biological Studies have come up with a way to disguise helpful molecules to sneak them past the brain’s defences

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