Two hours a day, Jeff Davis works at staying alive. He inhales a succession of medications, runs on a treadmill and sometimes performs breathing exercises that produce gurgly, crackling sounds.
It's tedious work, crammed into a life that includes a full-time job as a machinist and leisure time with his wife and two young children in the horse country north of Westminster. But it has paid dividends: A generation ago, few people with cystic fibrosis lived past their teens - and Davis is 35.
If there's a miracle in this story, it's that Davis is fairly typical, having soldiered through childhood with a closet full of medications and parents who spent untold hours thumping his torso to keep his lungs clear.
"They told my parents that if I lived to be a teenager, that would be about it," Davis said during a recent visit to Johns Hopkins Hospital's adult cystic fibrosis clinic, established a decade ago. "The fact they even have an adult clinic is pretty amazing."
Affecting 30,000 people in the United States alone, cystic fibrosis is an inherited disease that causes the body to produce thick, sticky mucus that can clog the lungs and damage the pancreas, interfering with the body's ability to absorb nutrients. As a result, victims are prone to dangerous respiratory infections and struggle to gain weight.
In the early 1960s, the median survival age was 10 years. Desperate parents watched frail children cough their way through life and eventually succumb to infections, even malnutrition.
But a steady progression of drugs, medical devices and improvements in disease management has made it possible for patients not only to survive longer, but also to attend college, have careers and raise families. By the early 1980s, median survival had risen to 21 years. Today, it is 37.
"We now expect children to live into adulthood and to be healthy as well," said Dr. Peter Mogaysal, director of the cystic fibrosis center at the Johns Hopkins Children's Center. "Several decades ago, most people with CF died in childhood, and it was the exception to have patients live to be an older adult."
To achieve that, patients face steep challenges - not just lung infections and the likelihood that they will someday die of the disease, but daily treatments that can sideline them from things they'd rather be doing.
"We're talking about the late teens, early 20s, a time when all of us are trying to get careers, find spouses and think about having a family," said Dr. Michael Boyle, who runs the adult clinic at Hopkins. "They're doing all those things - plus spending an hour or two maintaining their health."
Until the 1990s, there weren't enough adult survivors to justify a clinic of their own. Since the clinic's founding, the caseload has grown from 40 patients to 200.
"I went to medical school here, trained in adult medicine and saw one cystic fibrosis patient the whole time," said Boyle, a pulmonologist who graduated from Hopkins in 1990.
But a few years later, while subbing for a colleague at the pediatric clinic, Boyle noticed something odd: several young adults looking curiously out of place in a waiting room where youngsters sat on pint-sized chairs and played with toys.
In 1996, Boyle established one of the first adult cystic fibrosis clinics. Today, there are 96 in the U.S. accredited by the Cystic Fibrosis Foundation, which has funded virtually all the drug development that has led to survival gains.
Survival, though, is no easy task.
Patients can become resistant to the antibiotics that treat and prevent infections. They fight side effects that can include hearing loss and dizziness. They can lose lung function if they start skipping treatments. And a quarter develop diabetes and require insulin.
All these issues were evident one afternoon as Boyle and colleagues met to review patient histories before their appointments.
A man who had recently lost his brother to the disease worried about whether he was doing enough to stay healthy. A woman with a 2-year-old child had been coughing up blood.
A young man developed osteoporosis - the combined effect of medication, chronic inflammation and digestive problems. A college student had to connect herself to a feeding tube at night to keep her weight above 100 pounds.
Whatever their symptoms, patients suffer from a single underlying problem. By inheriting a mutant gene from each parent, they are saddled with a defective protein that sits on the surface of cells lining the lungs, airways and pancreas.
The protein is supposed to maintain a proper balance of salt and water, both inside and outside the cells. But instead, the salt concentrates in the cells, and the mucus lining the airways becomes thick and sticky - the bane of a patient's life.
Over the years, scientists have chipped away at the disease through incremental improvements in therapies. There are better antibiotics to prevent and treat infections and new drugs to thin out the mucus. There are also enzymes to compensate for chemicals the pancreas should make but can't.
Doctors push medications more aggressively than before and encourage patients to eat all the steak and dairy products they want. "Studies found that patients who eat higher levels of fat and more calories were actually living years longer," said Boyle.
But therapies treat symptoms, not the underlying defect that triggers them. So patients generally still see their lung function decline over time. The disease eventually overwhelms them, and they die when their lungs cannot deliver enough oxygen to the bloodstream.
At Hopkins and other specialty centers, doctors are testing a group of medications designed to make the protein work correctly. Any one of them could represent the quantum leap that doctors have so far found elusive.
"These are interesting and good times to be in cystic fibrosis research," said Dr. Craig Gerard, who treats patients at Boston Children's Hospital. "We now have drugs in development that directly target the nature of the disease."
Meanwhile, patients are reaching milestones never before thought possible.
Meg Heneberry, 24, was healthy enough to play high school sports and later competed on the women's lacrosse team at Northeastern University in Boston while studying mechanical engineering.
But six months ago, after infections sent her lung function into a downward spiral, she underwent a double lung transplant at the Boston hospital. In the process, she lost her hearing - the result of medications or a mini-stroke she might have suffered on the operating table, doctors said.
Despite these problems, she has learned to lip-read, holds down a job at an engineering firm and can take a deep breath without coughing.
"Things aren't all easier," she said in an e-mail, explaining that she still takes a battery of pills and wears a face mask in crowds to protect her lungs from germs. "It has sure been a struggle since September 11, when I received this gift of life, but it's worth it."
James Albright, 44, runs an International Baccalaureate program at a middle school in Northern Virginia. There, students barely take notice of an intravenous tube carrying medications into his arm.
When they married nearly 20 years ago, Albright and his wife faced an uncertain future. "I was pretty up-front about it," he said. "If we could get five good years out of it, it would be great. I couldn't promise anything beyond that. But married couples tend to live longer - my goal is 70s."
The couple adopted three boys, including one with cystic fibrosis. Men who have the disease are born with a natural vasectomy, lacking the duct that carries sperm from the testes, but they can conceive with reproductive assistance.
Female patients can also conceive - but they must consider whether they can endure the rigors of pregnancy. And, like adult males with the disease, they must consider how long they'll be around for the children.
"The question isn't whether you can; it's whether it's right for you," said Boyle. "It's a hard question to ask of someone who's 28 years old and trying to live a normal life. We try to be supportive but help them be realistic."
Jeff Davis and his wife, Kim, had two in vitro babies - Gwynneth, 3, and Gunnar, who is 7 months old. Kim had genetic tests that determined she wasn't a carrier, so there was no chance the children would be afflicted.
They live in a simple split-level that overlooks a landscape of rolling hills dotted with horses. Life at home seems relaxed, despite the lingering knowledge that his health isn't assured.
"Is it going to be a couple of years, or 20 years?" Davis said. "Am I going to be there in their teenage years when they need me? Am I going to be there to guide them? Am I going to see [Gwynneth] get married?
"You have to take it all into consideration, but you can't let it rule your life."