Headline Sep 26, 2014/

''' OF MICE AND OF MEN '''

EXPERIMENTS on mice are widely used to help determine which new cancer therapies stand a good chance of working in human patients.

Such studies are not perfect and, all too often, what works in a rodent produces little or no benefit in people. This has led researchers to explore the ways in which mice and men are dissimilar, in order to pick apart why the responses are different.

A new study now proposes that  the temperatures in which lab mice are kept is one thing that does matter. Mice, if left to their own devices, will seek places with a temp of around 30 degree C to minimise heat loss from their small bodies. But lab mice rarely enjoy such toasty climes.

Researchers tend to keep them at  20 - 26 degree C so that their cages stay cleaner for longer ( mice then drink and urinate less)  and so that lab technicians do have to endure sweltering conditions. It has not been seen as a problem because mice are perfectly capable of maintaining their body temperatures in cooler environments.

However, Elizabeth Repasky, an immunologist, at Roswell Park Cancer Institute in Buffalo, New York, wondered if there might be more to it than that and designed an experiment to find out. 

Dr Repasky and her colleagues put mice into two different types of enclosures: one sort kept at  22-23 degrees centigrade and the other at  32-33 C. The mice were left for two weeks to acclimatise before being injected with tumour cells.

The results, just published in the  Proceedings of the National Academy of Sciences, revealed that the tumours in the mice caged in the cooler environment showed a typical rate of growth whereas-

Those in the warmer mice grew 40-60% slower, depending on the cancer. Was this, Dr Repasky wondered, because their immune systems were functioning differently?

To investigate this, blood samples were collected from the mice and tested for the presence of the anti-tumour immune cells, known as  cytotoxic  T Lymphocytes. A striking increase in these cells was found in the tumours of the mice in the warmer housing.

The researchers also found an increase in the types of cell that promote future growth in the mice kept in cooler conditions. This suggested that warmer temperatures were in some way helping a more effective defence against cancer.

Another experiment was arranged to see if, given the choice, mice with cancer would move to warmer places. Both healthy and tumour -carrying mice were put in an apparatus with five chambers maintained at either 28, 30, 34 or 38 degrees C.

As expected, the healthy mice spent the most time in the 30 degree C chamber, but those with cancer stayed mainly in the  38 degree C one.   

Dr Repasky  argues that these effects are likely to be due to immunosuppressive responses of  cold  ''stress''. The mice in cool laboratories maintain stable body temperatures, she suspects, by diverting resources away from their immune functions and this-

In turn makes them less capable of fighting cancer. Because of the implications for cancer research she proposes that it would be better if the ambient temperatures in which lab mice are housed is raised so that their immune systems can function more normally.

Is there also a lesson to be learned from lab mice for human cancer patients? Dr Repasky explains that, unlike mice kept in cages, most humans are able to manipulate their environment by putting on extra clothes or turning up the heating, so should not experience chronic cold stress.

Still, she adds, some cancer patients do indeed report feeling chills, although cold is only one of many forms of stress that the body has to cope with.

Others such as psychological stress, might also have an immunological effect on the progress of the disease.  

With respectful dedication to the Students, Professors and Teachers involved in cancer research. See Ya ll on !WOW!  -the World Students Society Computers-Internet-Wireless:

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