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Research Roundup: Echolocation, neurological disease and breast cancer clinical trials

Bats use echolocation to find their prey. Dolphins use echolocation when navigating the waters. Our research roundup highlight this week found that echolocation in unrelated species has resulted from the same set of genetic changes. (Photo: Creative Commons)

Each week, The Daily’s Science & Tech section produces a roundup of the most exciting and influential research happening on campus or otherwise related to Stanford. Here’s our digest for the week of Sept. 29 – Oct. 5.

Echolocation in unrelated species found to have same genetic changes

Echolocation, a navigation technique used to find prey by disparate species such as bats, dolphins and whales, was found to have independently arisen from a set of 18 genes involved in cochlear ganglion development in a study by Stanford researchers published online in Proceedings of the National Academy of Sciences on Sept. 30.

Gill Bejerano, Stanford professor of developmental biology, computer science, pediatrics and biomedical data science, led scientists in discovering these genetic changes in evolutionary adaptation. Echolocation is the biological process in which animals emit sound waves that bounce off objects and reflect back to the animal, and this process is used to locate food or navigate their surroundings in the environment.

The researchers developed a technique that involves examining the genomes of animals that share unique physical characteristics and DNA changes not present in other closely related animals. To study echolocation, scientists compared the genetic sequences of bat species who use echolocation to bat species who do not, looking for genes with changes common to echolocating bat species, but were different than other animals.

“Not only is it breathtaking to see how these very different species carved their own evolutionary niches for themselves through independently acquiring similar genetic changes, it’s beneficial to our understanding of our own physiology and development,” Bejerano said in an interview with Stanford Medicine News.

Collaborative study finds the cause of a rare neurological disease

A collaborative study between scientists from the Stanford School of Medicine, University of California, San Francisco and the University of Cambridge found that the cause of a rare neurological disease is due to an increased sensitivity of iron in the brain in a study published in Cell Stem Cell on Oct. 3.

Led by Marius Wernig, Stanford professor of pathology, and David Rowitch, adjunct professor of pediatrics and neurological surgery at UCSF, the team is dedicated to finding treatments to Pelizaeus-Merzbacher disease, a rare inherited disorder that weakens the brain and spinal cord. Symptoms include weak muscle tone, involuntary eye movements and delayed motor skill development.

Pelizaeus-Merzbacher is associated with mutations in the gene PLP1. Normal function of PLP1 causes development of the myelin sheath, which coats and insulates neurons to help transmit nerve signals in healthy patients. In the study, researchers observed that cells with mutated PLP1 have characteristics indicating iron toxicity, which can have harmful effects to cells.

The researchers found that by removing iron from the brain with a drug that could chelate, or bind iron, cells in Pelizaeus-Merzbacher patients were more likely to survive. Clinical trials are expected to proceed in Europe to evaluate the efficacy of the drug in treating the disorder.


Drug combo increase lifespan of breast cancer patients, results from clinical trial show

Women receiving hormone therapy along with an additional second drug when treating a common type of metastatic breast cancer can live roughly nine months longer than women who receive hormone therapy alone, say a clinical trial led by George Sledge, oncology chief at the Stanford School of Medicine.

Breast cancer cells express estrogen receptors often need the hormone estrogen to proliferate and grow, and these cancers are classified as hormone-receptor-positive. Hormone therapy is a first-step approach in treating breast cancer as this will prevent the body from producing estrogen, or will prevent estrogen from binding to cancer cells.

The randomized, double-blind trial enrolled around 700 women in 142 cancer centers across 19 countries. The second drug, abemaciclib, is part of the class of molecules known as CDK4/6 inhibitors, which work to prevent cancer cells from dividing by targeting critical proteins. The drug combination of hormone therapy and abemaciclib has been indicated to extend the overall survival rate of women, results from the phase-3 clinical trial show.

“Data from this trial pretty clearly shows that if you take this drug combination, you live longer,” Sledge said in an interview with Stanford Medicine News, “It also delays the point at which we need to start these women on chemotherapy. So not only do you live longer, you have a better quality of life.”

The results from the clinical trial, known as MONARCH 2, were published online in JAMA Oncology on Sept. 29; additionally, a presentation of the findings was presented at the 2019 European Society of Medical Oncology conference meeting in Barcelona, Spain.

Contact Derek Chen at derekc8 ‘at’ stanford.edu.

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