From guns to guts, new treatments are literally in the spotlight

(Correction: Because of an editing error, a headline on in yesterday's Health/Science section was inaccurate. It should have read: ''From your gums to your guts, new treatments are literally in the spotlight.)

It's still on the drawing boards in The Fens, but researchers say their new device -- tiny enough to fit inside a clenched mouth -- will be the best invention since the toothbrush. They envision legions of toothbrush-challenged consumers popping this denture-sized ''intraoral light source" in their mouths, biting down to turn the gadget on, and then letting its bright blue light zap away plaque-causing germs -- in just 30 seconds

Already, the gizmo, developed at Boston's Forsyth Institute, has been shown to kill the ''bad" bacteria and ''restore balance and harmony in dental plaque," said Nikos Soukos, DDS, director of Applied Molecular Photomedicine at the dental research center.

Four decades after doctors first harnessed high intensity lasers for surgery, scientists are now making dramatic advances like Forsyth's in training lower-intensity visible light -- the blues, greens, reds, and yellows of the rainbow -- on diseases like gingivitis, ulcers, and even cancer. The FDA has already approved the use of light therapy to treat symptoms of cancer of the lung and esophagus.

''We are learning there are many ways we can use light to treat patients in a way that is minimally invasive and not harmful to the body," said Cliff Robinson, assistant director of Boston University's Photonics Center, which links private industry with academia in the medical use of light.

The Forsyth research team stumbled across the disease-fighting power of blue light when one of its members, who was researching the safety of a tooth whitening procedure, noticed that the process also appeared to reduce patients' gum inflammation.

The light's energy, the researchers theorized and later proved, was killing light-sensitive bacteria linked to gum disease. At specific wavelengths, the energy of light can trigger chemical changes in the cell that lead to cell death.

The scientists, led by Max Goodson, Forsyth's director of clinical research, have yet to conduct a ''huge clinical study," to compare how their blue light invention stands up to the lowly toothbrush, Soukos said.

But so far, Forsyth's device appears safe and patients don't even need to wear sunglasses to protect their eyes from radiation, the way they do during tooth whitening procedures. They also have no pain and no evident side effects.

Boston researchers have led such advances in photomedicine for decades, pioneering the use of visible spectrum ''rainbow" light to remove hair and tattoos, and combat age-related blindness and acne, among other problems.

Using light to kill bacteria also seems to avoid the problem -- common with antibiotics -- of resistance. No matter how much light is aimed at the bacteria, they seem unable to develop the ability to outsmart the beams, the way they do when bombarded with antibiotics.

''We and other laboratories have intentionally been shining light on bacteria to find out if there is an emergence of resistance, and so far we haven't seen it," said Dr. R. Rox Anderson, director of the Wellman Center for Photomedicine at Massachusetts General Hospital and a professor of dermatology at Harvard Medical School.

H. pylori, a common stomach bacteria that has been implicated in stomach cancer and ulcers, has been unable to survive blasts with a blue ''light wand," according to LumeRX, a two-year-old local company that has tested the wand in animals.

''Blue light seems to cause the H. pylori to self destruct, and it seems to not harm anything else, even other bacteria in the stomach that you need for digestion," said Tom Hennessey, chief financial officer at LumeRX, which is housed at Boston University's Photonics Center.

The foot-and-a-half-long wand fits into a slender tube that is threaded through the mouth and esophagus into a patient's stomach. Once there, it beams blue light onto the stomach walls to kill the bacterium. The company hopes to start trials in humans next year.

Another form of light treatment, called photodynamic therapy, is used to attack tumors in the skin, lung, and esophagus. In photodynamic therapy, a chemical is injected into a patient or spread on the skin, and the chemical is only activated when a specific light hits it.

Researchers at the Wellman Center are also exploring the use of photodynamic therapy to reconnect tiny nerves and tissues that are severed in accidents or need to be repaired after surgery. Harvard dermatology professors Irene Kochevar and Robert Redmond are developing a procedure they call ''light-activated tissue bonding." They apply a pink dye to torn tissue to stain it, then expose the area to low-level green light for about two minutes, triggering the stained tissue to stick together.

''One day after you do the bonding, the dye is gone. There are no sutures or staples," Anderson said.

''Light-activated tissue bonding could be used all over body, in plastic surgery or internal surgery," he added. ''It works very well in small, delicate structures where we are trying to do repair."

The researchers have performed the procedure on animals and hope to begin human trials next year, focusing on repairs to the cornea.

Certainly too much light, such as overexposure to the sun's ultraviolet rays, can cause harm, too. Anderson said researchers are proceeding with caution.

''These light-activated drug approaches carry very low risk, and we like that," Anderson said. ''So far, so good."