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Giorgia squeri via Wikimedia Commons // CC BY-SA 4.0

Are Cold Mice Skewing Cancer Study Results?

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Giorgia squeri via Wikimedia Commons // CC BY-SA 4.0

Designing experiments is a tricky task. In order to prove or disprove a hypothesis, scientists first have to eliminate or account for the influence of as many variables as possible. But in order to do that, first they must realize that these variables exist. A review article published today in the journal Trends in Cancer shows that standard laboratory temperatures—which are comfortable for humans but chilly for mice—are likely affecting biomedical study results. 

As oversights go, this is a pretty big one. Lab mice and rats are the subjects of more than 100,000 journal articles every year … and those are just the experiments that are published. But unlike dogs, cats, rabbits, or chimpanzees, mice and rats are not protected under the 1966 Animal Welfare Act, which regulates how research animals are treated. This lack of protection means that there has been relatively little research, and less regulation, regarding their treatment. 

This is a bad situation for rats and mice, and it’s not great for us, either. The mouse model, as it’s known, is generally seen as a pretty good indicator of how a given drug or medical occurrence may affect humans. So if tests on a cold mouse yield different results from those done on a mouse at a comfortable temperature, as two immunologists now argue, then millions of studies on drugs and disease have been affected.

Today, rodent research labs are kept between 68°F and 78.8°F. Researchers wear layers of protective gear, including gowns, gloves, and masks, so a higher temperature might cause them to overheat. Keeping the thermostat down also helps keep down the smell.

Image Credit:Guanxi (Christina) Qiao

But a mouse’s ideal temperature averages between 86°F and 89.6°F. A 70°F room will cause mice to shiver, which uses up their energy and affects their metabolism, blood flow, and heart rate. Realizing this, immunologists Bonnie Hylander and Elizabeth Repasky decided to take a look at the relationship between mouse temperature and study results. In 2013, they found that a cold mouse is less able to fend off tumors than one that’s toasty warm—a finding that had big implications for cancer drug research.

But these findings were just the start. Hylander and Repasky conducted a sweep of scientific literature, looking for studies like theirs. They found that researchers of obesity, inflammation, atherosclerosis, and a number of other diseases all concluded that keeping mice cold led to “significant differences in experimental outcomes.” 

"Most people only look at results from experiments at standard lab temperatures," Hylander said in a press statement. "They're not necessarily aware that if you repeat the experiments with mice at a different temperature, you might get a different outcome." 

Unfortunately, there’s no quick fix to be had here. “The mice want different temperatures for different parts of the day,” animal welfare scientist Brianna Gaskill told Dan Engber at Slate. “There is no way that humans can pick a single, perfect temperature for mice.” And, as mentioned earlier, what’s good for mice is not so good for researchers. 

Hylander and Repasky aren’t suggesting that labs simply turn up the heat. One approach might be for researchers to experiment with keeping the mice warm in incubators, or offering them more nesting material. They also recommend that researchers consider the effects of temperature in both their experimental design and their analysis of their results in the future. 

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25 Benefits of Adopting a Rescue Dog
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According to the ASPCA, 3.3 million dogs enter shelters each year in the United States. Although that number has gone down since 2011 (from 3.9 million) there are still millions of dogs waiting in shelters for a forever home. October is Adopt a Shelter Dog Month; here are 25 benefits of adopting a shelter dog.

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Brooklyn Museum, Charles Edwin Wilbour Fund, 37.406E
New Smithsonian Exhibit Explains Why Felines Were the Cat's Meow in Ancient Egypt
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Brooklyn Museum, Charles Edwin Wilbour Fund, 37.406E

From bi-coastal cat cafes to celebrity pets like Lil Bub, felines are currently enjoying a peak moment in popular culture. That’s part of the reason why curators at the Smithsonian’s Arthur M. Sackler Gallery—which will re-open to visitors on Saturday, October 14, following a 3-month closure—decided to dedicate a new exhibition to ancient Egypt’s relationship with the animals.

Divine Felines: Cats of Ancient Egypt” looks at the cultural and religious importance of cats, which the Egyptians appreciated long before YouTube was a thing and #caturday was a hashtag. It's based on a traveling exhibition that began at the Brooklyn Museum in New York City. On view until January 15, 2018, it's one of several exhibits that will kick off the grand reopening of the Smithsonian’s Freer and Sackler galleries, the conjoined national museums of Asian and Middle Eastern Art.

The Freer has been closed since January 2016 for major renovations, and the Sackler since July 2016 for minor ones. The upgraded institutions will make their public debut on October 14, and be feted by a free two-day festival on the National Mall.

Featuring 80 artworks and relics, ranging from figurines of leonine deities to the tiny coffins of beloved pets, "Divine Felines" even has a cat mummy on loan from the Smithsonian’s National Museum of Natural History. These objects span from the Middle Kingdom (2008 to 1630 BCE) to the Byzantine period (395 to 642 CE).

An ancient Egyptian metal weight shaped like a cat, dating back to 305 to 30 BCE, on view at the Smithsonian’s Arthur M. Sackler Gallery
Weight in Form of a Cat, 305 to 30 BCE, Bronze, silver, lead
Brooklyn Museum, Charles Edwin Wilbour Fund, 36.114

The term “cat” is used loosely, as the Egyptians celebrated domestic mousers and fearsome predators alike.

“The Egyptians were close observers of nature, so they were observing cat behaviors,” Antonietta Catanzariti, the exhibition's in-house curator, tells Mental Floss. “They noticed that cats and lions— in general, felines—have aggressive and protective aspects, so they associated those attributes to deities.”

The ancient Egyptians viewed their gods as humans, animals, or mixed forms. Several of these pantheon members were both associated with and depicted as cats, including Bastet, the goddess of motherhood, fertility, and protection; and Sakhmet, the goddess of war and—when appeased—healing. She typically has a lion head, but in some myths she appears as a pacified cat.

A limestone sculptor's model of a walking lion, on display at the Smithsonian's Arthur M. Sackler Gallery.
Sculptor's Model of a Walking Lion, ca. 664 to 630 BCE, limestone
Brooklyn Museum, Charles Edwin Wilbour Fund, 33.190

While Bastet was a nurturer, Sakhmet—whose name means “The Powerful One”—could use her mighty force to either slay or safeguard humanity. These characterizations are typical of the ancient Egyptian worldview, which perceived the universe in dualistic terms. “There’s always a positive and a negative,” Catanzariti explains.

Contrary to popular belief, however, ancient Egyptians did not view cats themselves as gods. “The goddess Sakhmet does have the features as a lion, or in some cases as a cat, but that doesn’t mean that the Egyptians were worshipping cats or lions,” Catanzariti says. Instead, they were simply noting and admiring her feline traits. This practice, to an extent, also extended to royalty. Kings were associated with lions and other large cats, as they were the powerful protectors of ancient Egypt’s borders.

These myriad associations prompted Egyptians to adorn palaces, temples, protective amulets, ceremonial vessels, and accessories with cat images. Depending on their context, these renderings symbolized everything from protection and power to beauty and sexuality. A king’s throne might have a lion-shaped support, for example, whereas a woman’s cosmetics case might be emblazoned with a cat-headed female goddess of motherhood and fertility.

An ancient Egyptian figurine of a standing lion-headed goddess, on display at the Smithsonian's Arthur M. Sackler Gallery.
Figurine of a Standing Lion-Headed Goddess, 664 to 630 BCE, Faience
Brooklyn Museum, Charles Edwin Wilbour Fund, 37.943E

While cats were linked with heavenly figures and kings, they were also popular domestic pets. Their ability to catch vermin made them an important addition to households, and owners loved and anthropomorphized their pets just like we do today.

Egyptians often named, or nicknamed, their children after animals; Miit (cat) was a popular moniker for girls. It's said that entire households shaved their eyebrows in mourning if a house cat died a natural death. Some also believe that cats received special legal protection. (Not all cats were this lucky, however, as some temples bred kittens specifically to offer their mummified forms to the gods.) If a favorite cat died, the Egyptians would bury them in special decorated coffins, containers, and boxes. King Tutankhamen, for example, had a stone sarcophagus constructed just for his pet feline.

An ancient Egyptian bronze cat head adorned with gold jewelry, on display at the Smithsonian's Arthur M. Sackler Gallery.
Cat's Head, 30 BCE. to third century CE, bronze, gold
Brooklyn Museum, Charles Edwin Wilbour Fund, 36.114

“Divine Felines” breaks down these facts, and more, into five thematic sections, including “Cats and Kings"; “Cats and Gods”; “Cats and Death”; “Cats and Protection”; and “Dogs as Guardians and Hunters.” Yes, there’s also an exhibition section for dog lovers—“a small one,” Catanzariti laughs, that explains why canines were associated with figures like Anubis, the jackal-headed god of mummification and the afterlife.

Did the ancient Egyptians prefer cats to dogs? “I would say that both of them had different roles,” Catanzariti says, as dogs were valued as hunters, scavengers, and guards. “They were appreciated in different ways for their ability to protect or be useful for the Egyptian culture.” In this way, "Divine Felines" is targeted to ailurophiles and canophiliacs alike, even if it's packaged with pointed ears and whiskers.

An ancient Egyptian cat coffin, on display at the Smithsonian's Arthur M. Sackler Gallery.
Coffin for a Cat, 664 to 332 BCE, or later, Wood, gesso, paint, animal remains
Brooklyn Museum, Charles Edwin Wilbour Fund, 37.1944Ea-b


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