'Globally, viral diarrhoea kills between 2.5 to 3 million children under five each year. In western countries children rarely die, but it costs the health care industry an estimated $1 billion annually.
'In the poorest regions of the world - such as sub-Saharan Africa - which can't afford even the most basic oral re-hydration (salt and sugar in drinking water), kids fare far worse. Here one in 200 children dies from a combination of malnutrition and diarrhoea. This quickly leads to dehydration, cardiovascular damage and death.
'My goal is ultimately to develop a vaccine to protect children from this fate. At the University of Texas I teach students in both medical and graduate schools, and run three experimental labs that look at how salt and water balance is maintained within gut tissues.'
So you want to be a Scientist?
'Intellect, creativity and dogged perseverance play a large role in any science. You are simultaneously explorer, architect, engineer and scribe. In this career you will never be bored, doing the same old thing all your life.
'There's no shame in failure: experiments fail all the time. It is what often leads to the right answer.'
The gut is intricate. Its nervous system, important in extracting from food the nutrients and fluid for life and ridding the body of waste, is nearly as complex as the brain. Diarrhoea is a complex physiological response involving the nerves, muscle and epithelial tissue.
Sometimes the lymphatic system is implicated, too. Rotavirus causes watery (secretory) diarrhoea. It can infect all ages, but mainly produces symptoms in the very young. Children become dehydrated when significant amounts of water and salt are lost in diarrhoea.
Secretory diarrhoea is linked to a recently identified protein, made by rotavirus. This causes the epithelial cells lining the gut wall to leak excessive levels of water and salt. Other pathogens also do this. For instance, cholera toxin, made by the microbe Vibrio cholerae, causes another type of secretory diarrhoea.
A different form of fluid leakage called osmotic diarrhoea results from damage to the cells or tissue by parasitic infections, such as ameboid dysentery. This destroys the integrity of the gut barrier allowing fluid and blood into the stool.
Scientist under the microscope:
What scientific discovery would you save from a burning building?
'I would like to save the actual process of discovery. We don't own knowledge, we uncover it for others to use and understand further. Once a discovery is made, information is disseminated very quickly among the scientific community.'
Your favourite bit of kit?
'My confocal laser scanning microscope (CLSM) which looks inside cells at very high resolution. It's expensive - a new unit costs half a million dollars. It can't reveal individual proteins, rather it maps the interior of the cell to reconstruct the architecture of sub-cellular life.'
What was the biggest hurdle youve had to overcome in your career?
'Secondary school! I had a problem with reading, my spelling was weak and I tended to jumble up letters. I was placed in a remedial class and spent my first year finding a way to decipher school work and "catch up".'
Find a biomedical exhibition funded by The Wellcome Trust at a regional science centre near you
The Young Physiologists pages on The Physiological Society of London website have details of careers conferences and information on PhD opportunities
The Medical Research Council raises awareness of medical, ethical and social implications of research. It offers studentships and personal awards for research training and career development
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