Posts Tagged ‘lizard’

By Bradley J. Fikes

A diabetes drug developed by a San Diego biotech company from a venomous lizard’s saliva reduces Parkinson’s disease symptoms, according to a study published Thursday.

The placebo-controlled study of 62 patients found the drug, exenatide, provided statistically significant effectiveness in preserving motor control. It may actually slow down disease progression, although this has to be confirmed with more research.

For Parkinson’s patients, the trial represents stronger grounds to expect more effective treatments. For San Diego’s life science community, it represents another example of the benefits of original research and innovation.

The study was published in The Lancet by researchers led by Thomas Foltynie and Dilan Athauda, both of University College London in London, England. While the study wasn’t particularly large, with 62 patients, it was placebo-controlled, and is in line with a previous clinical study published in 2014.

Exenatide was found in Gila monster saliva by Dr. John Eng, an endocrinologist at Bronx Veterans Affairs Medical Center in New York. The venomous lizard, native to the Southwestern United States and northwestern Mexico, delivers excruciating pain with its bite.

San Diego’s Amylin Pharmaceuticals licensed the discovery in 1996. Further development yielded exenatide, sold under the brand name Byetta.

The drug became a hit, providing a major reason for Amylin’s 2012 purchase for $7 billion by Bristol-Myers Squibb. As for Amylin, the company was disbanded and no longer exists.

Exenatide/Byetta reduces insulin resistance in Type 2 diabetes, allowing for better control of blood glucose. There’s evidence that Parkinson’s disease is also related to problems with insulin signaling.

The new clinical study improves on the previous study because it is placebo-controlled, according to an accompanying commentary in The Lancet. But the study has limitations that prevent it from being considered definitive.

“Whether exenatide acts as a novel symptomatic agent or has neuroprotective effects on the underlying Parkinson’s disease pathology remains unclear, but Athauda and colleagues’ study opens up a new therapeutic avenue in treatment of Parkinson’s disease,” the commentary stated.

Christian Weyer, M.D., a former Amylin executive, said one of the most interesting parts of the study was exenatide’s potential for modifying the course of Parkinson’s disease. Weyer is now president of Chula Vista’s ProSciento, a clinical services provider.

Patients were measured on motor skills after getting 48 weeks of injections, either with exenatide or placebo. The treated group showed an advantage of 4 points on a 132-scale test, which was statistically significant.

Exenatide mimics the action of a hormone, and such drugs often show disease-modifying properties, said Weyer, who was Amylin’s Senior Vice President of Research and Development.

“It’s not conclusive that exenatide has the potential for disease-modification, but I was impressed by the fact that the endpoint of the test was in the off-medication period, so you actually assess whether there’s an effect even after the treatment had been stopped,” Weyer said.

Amylin had performed early preclinical research on exenatide for Parkinsons’ disease, Weyer said. The research was funded by a small grant from the Michael J. Fox Foundation.

In chronic diseases such as Type 2 diabetes and Parkinson’s, finding disease-modifying therapies is the “Holy Grail,” Weyer said.

“These are life-long diseases, and anything you can do to either delay or prevent the onset of the disease, or to slow its progression over a long period of time” has great benefit, Weyer said.

Insulin has many biological roles in the body, so it’s not surprising that an abnormal response to insulin could play a role in Parkinson’s disease as well as diabetes, Weyer said.

http://www.sandiegouniontribune.com/business/biotech/sd-me-exenatide-parkinsons-20170803-story.html

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When zoologist Ivan Sazima went for a walk in the park in southeastern Brazil on a warm September day in 2013, he was hoping to find noteworthy animal behavior to study.

But he did not expect to witness lizard necrophilia. Right in front of him, he saw a male reptile trying to court and mate with a dead female of the same species, Salvator merianae, commonly known as the black-and-white tegu.

“I felt a sense of wonder, because I did not observe this behavior in lizards before, only in frogs,” said Sazima, of the Zoology Museum of the University of Campinas in São Paulo.

Necrophilia occurs in other lizard species, but it’s the first documented instance in black-and-white tegus, one of the most common lizards in South America.

Sazima watched the male lizard flick his tongue at the deceased female—a common courtship behavior—and try to mate with her for about five minutes. Then a group of geese showed up, causing the confused suitor to flee.

The scientist returned to the same spot the next afternoon. By that time, the corpse was bloated and had begun to rot and smell.

But even the stench did not discourage another male black-and-white tegu from attempting to have sex with the dead body—this time for nearly an hour.

During this time, the new male embraced the dead female and bit her head, another courtship behavior. He rested on her body from time to time, taking breaks from the exhausting sexual activity, before finally flicking his tongue on the corpse and leaving, according to the study, published in January in the journal Herpetology Notes.

Sazima’s encounter adds to several reported instances of necrophilia in the animal world.

Henrique Caldeira Costa of the Federal University of Minas Gerais, in Belo Horizonte, Brazil, reported necrophilia in male green ameiva lizards in Brazil in 2010. The female had likely been hit by a vehicle on the road, he wrote in the journal Herpetology Notes.

In another incident, Kamelia Algiers, a biologist at Ventura College in California, described a necrophiliac long-nosed leopard lizard in Nevada, in the western United States.

The animal attempted to copulate with a roadkill female, whose “intestines were sticking out, and there were ants crawling all over it,” said Algiers, who described the event in 2005 in Herpetological Review.

What’s more, mating with the dead isn’t restricted to reptiles and amphibians: Ducks, penguins, sea lions, pigeons, and even ground squirrels have also been caught in the grisly act.

Why Mate With the Dead?

So, what exactly draws some male lizards to female corpses? Despite many scientific observations, “necrophilia in lizards is still poorly understood,” said Costa, who wasn’t involved in the new tegu research.

But as for those amorous black-and-white tegus, the Zoology Museum’s Sazima has a theory: The males may have been simply fooled into thinking the female was alive.

For one, the dead female lizard was still warm: Though dead, her body temperature was probably close to that of the ambient air. And her pheromones, likely still detectable on her body after death, may have allured the male admirers.

Federal University’s Costa agrees this is a valid theory, and suspects that the female’s high body temperature and pheromones might have explained the lizard necrophiliac he described in 2010.

Interestingly, necrophilia seems to be beneficial for at least one species: a small frog in Amazonian Brazil called Rhinella proboscidea.

A 2013 study showed that R. proboscidea males can extract eggs from dead sexual partners and fertilize them, a process called “functional necrophilia.”

http://news.nationalgeographic.com/news/2015/02/150227-necrophilia-lizards-animals-mating-sex-science-brazil/?google_editors_picks=true

Thanks to Da Brayn for bringing this to the attention of the It’s Interesting community.