The top three news stories of the week, as chosen by our resident students. This week’s top stories include using live worms to find a cure, development of brain-like computer systems, and human-sheep hybrids.

By Federico Dona

Infecting subjects with live worms to find a cure

In Leiden University, Roestenberg team1 is trying to use a “creative” and “innovative” way to fight schistosomiasis disease.

This disease that sickens millions of people in Africa, the Middle East, and Latin America and kills thousands each year. There is no schistosomiasis vaccine and only one old, mostly ineffective drug, praziquantel, to treat it.

The researchers infected people with Schistosoma mansoni, one of five tiny waterborne worm species that cause schistosomiasis. Infecting humans with the live worms could help speed up the development of new interventions.

Roestenberg’s team has designed the experiment to prevent the parasites from reproducing, and she says the risk to volunteers is extremely low. In nature, people become infected with both male and female parasites, but Roestenberg uses only males, so there will be no eggs and thus, she says, no symptoms. And when the study ends in 12 weeks, the volunteers will be given praziquantel to cure them. However, this part of the study is under debate and some researchers argue that the subjects will not get rid of the parasites at the end.

Once infected, the volunteers will return to the lab every week, so the research team can test their blood for a molecule called CAA, which the worms regurgitate from their stomachs. The presence of CAA indicates that the worms are still alive; in future trials, its absence might mean that a vaccine or drug has worked. Some schistosomiasis scientists agree that the potential benefits justify the minimal risks. “My hope is that it would hugely accelerate identification of worthwhile candidate vaccines,” says Alison Elliott of the London School of Hygiene & Tropical Medicine, who works at a joint Ugandan and U.K. research unit in Entebbe.

Worm
In nature, male and female Schistosoma mansoni worms pair up within the host.

‘Memtransistor’ – a step towards brain-like computation

Computer algorithms might be performing brain-like functions, such as facial recognition and language translation, but the computers themselves have yet to operate like brains.

“Neural networks can achieve complicated computation with significantly lower energy consumption compared to a digital computer” said Northwestern University’s Mark C. Hersam.

In recent years, researchers have searched for ways to make computers more neuromorphic, or brain-like, in order to perform increasingly complicated tasks with high efficiency. Now, the research team has developed a novel device called a “memtransistor,” which operates much like a neuron by performing both memory and information processing. Supported by the National Institute of Standards and Technology and the National Science Foundation, the research was published in Nature.

The memtransistor builds upon work published in 2015, in which the team used single-layer molybdenum disulfide (MoS2) to create a three-terminal, gate-tunable memristor for fast, reliable digital memory storage. Memristor, which is short for “memory resistors,” are resistors in a current that “remember” the voltage previously applied to them. But now the researchers have updated the device from a single unit to a complex and multicomponent device that can reproduce the gate-tunable memristive responses across large arrays of devices. “This is even more similar to neurons in the brain,” Hersam said, “because in the brain, we don’t usually have one neuron connected to only one other neuron. Instead, one neuron is connected to multiple other neurons to form a network. Our device structure allows multiple contacts, which is similar to the multiple synapses in neurons.”

Next, Hersam and his team are working to make the memtransistor faster and smaller. “We believe that the memtransistor can be a foundational circuit element for new forms of neuromorphic computing,” he said.”

Read the full article here: 10.1038/nature25747

compubrain
This is the memtransistor symbol overlaid on an artistic rendering of a hypothetical circuit layout in the shape of a brain.

New horizon in organ transplant: Sheep-Human Hybrids give new hope.

Organ donation is a huge problem worldwide with demand for organs much higher than donations. To solve this problem different teams around the world are trying different methods from human blood filters through pig lungs as they inhale and exhale (in the University of Maryland School of Medicine), 3-D printing organs in the lab or developing artificial, mechanical organs. However, some scientists are making chimeras—hybrids of two different species—in the hopes of growing human organs in pigs or sheep.

It is using this method that a current research breakthrough is moving researchers a small step closer to growing human organs for medical transplant. Researchers have created the second successful human-animal hybrids: sheep embryos that are 0.01-percent human by cell count.

To make this embryo, researchers isolate one animal’s stem cells, which can develop into any cell type in the body. They then inject some stem cells from one species into the embryo of another. If the embryo’s DNA is hacked so that it does not grow a particular organ, the interloping cells would be the only ones that could fill in the gap. In this way, researchers could grow a human liver inside of a living pig, for example.

Recently, during the American Association for the Advancement of Science annual meeting in Austin, researcher Pablo Ross of the University of California announced that he and his colleagues have fine-tuned the procedure—boosting human cell counts in sheep embryos to one in ten thousand.

“We think that that’s still not probably enough to generate an organ,” Ross said during a press briefing. About one percent of the embryo would have to be human for the organ transplant to work.

“The contribution of human cells so far is very small. It’s nothing like a pig with a human face or human brain,” Stanford University researcher Hiro Nakauchi, Ross’s collaborator, said at the meeting. “All of these approaches are controversial, and none of them are perfect, but they offer hope to people who are dying on a daily basis,” he said. “We need to explore all possible alternatives to provide organs to ailing people.”

embryo
This pig embryo was injected with human cells early in its development and grew to be four weeks old (2017).