La Saliva

Just spit it out

The microbes that inhabit the human mouth have a lot to say about one’s general health. That’s part of the motivation behind a massive new push to catalog these oral bacteria.Floyd Dewhirst is well aware that spit has a lowly status in the minds of most people.
The Forsyth Institute, which opened its doors in 1910 to offer dental care to underprivileged children, has amission to study, among other applications, ways to prevent cavities or treat periodontal disease.
And so, as Dewhirst set out to scrutinize saliva, he was laying the groundwork for much larger feat:he aimed to build the first comprehensive database of the microbes inhabiting the human mouth and use it to diagnose and treat both oral and systemic disease.
Whereas our bodies harbor about a 1015microbial organisms, they typically contain only 1014 human cells. In other words, “we’re only one-tenth mammal,” Dewhirst explains.
One reason is that many oral microbes are anaerobic and thereforequickly killed by oxygen.
Each man bears a similar head of neat-cropped gray hair, silver- rimmed spectacles and the typical garb of New England biomedical researchers: khaki slacks paired with anoxford shirt. They work closely together.
Paster started designing radioactive DNA probes that could bind to and flag the presence of specific microbes. These DNA probes could help identify the microbialculprits in disease, he reasoned, and such a diagnostic would make a better selling point for the project.
Paster and Dewhirst have now identified and classified an estimated 600 different microbialspecies, 60% of which cannot be cultivated outside the mouth.
Saliva is complex, a mix of human and microbial material.
Meanwhile, Forsyth pharmacologist Max Goodson has found a surprising linkbetween oral bacteria and obesity. He had been looking at saliva samples from nearly 700 women for genes that might relate to weight regulation. To his surprise, 90% of the obesity in the women was...