Stopping Infections Before They Start…Patients in intensive care units (ICU) are already ill. When they have to be on ventilators for breathing support, contracting pneumonia can seriously affect recovery. Furthermore, it may be difficult to detect pneumonia because the patient’s underlying condition masks the symptoms. “If we can determine which patients are getting an infection ahead of clinical symptoms, we can start antibiotic therapy earlier and head it off,” says Dr. J. Perren Cobb, director of Washington University’s Center for Critical Illness and Health Engineering. He and other researchers at the School of Medicine have validated the use of gene chip technology to rapidly detect pneumonia in ventilator patients.
GeneChip™ is a trademarked product by Affymetrix, a leader in molecular genomics. It became possible in the late 1990s to study hundreds of thousands of genes at a time. Once a sequence becomes 20 to 30 genes long, the sequence becomes unique, like a fingerprint. The longer the sequence beyond that, the more unique. On a glass chip 1.2 cm2 a unique sequence at a unique position (a piece or chip of the gene) can be documented. The 85-gene sequence chosen for the gene chip Cobb uses is a generic sequence most people have.
Researchers can look at specific cells of interest, like the white blood cells that contain proteins that fight infection. With the start of an infection, white blood cells increase and change. With this technology, researchers can take a blood sample from the patient, break the cells open, gather the RNA and tag it with a fluorescent label. They then mix it with the DNA on the GeneChip and the RNA sticks to the complementary DNA. The amount of fluorescence correlates to the amount of RNA at a specific location, indicating whether white cells are responding to an infectious agent.
The Washington University team is the first to report in animal models, and in humans changes over time. They conducted a pilot study last year of a small cohort of patients, half of which developed ventilator pneumonia. There were small but measurable changes in white blood cell activity shown by the GeneChip days before clinical symptoms developed.
Cobb and his national colleagues are designing a multi-site study to test prospective patients and get treatment started earlier on patients who develop changes in the activity of the 85-gene sequence, in order to head off the catastrophic effects of pneumonia in this already compromised population. “Several million people are admitted to ICUs yearly in this country. If we can treat people before they develop clinical symptoms, we can significantly improve their ability to recover,” Cobb notes.
He calls this technology a ‘reiboleukogram.’ “It’s an electrocardiogram for the immune system,” he says. “The technology has implications far beyond ventilator patients in critical care units. The Department of Defense is interested. They could, for example, check sailors for subclinical disease before prolonged submarine trips, or check people who might have been exposed to germ warfare.”
Pain and Itching: Different Receptors…In the past, scientists regarded itching as a less intense bodily response to pain. But researchers at Washington University School of Medicine have determined that itching and pain have different molecular mechanisms, and they have separated the sensations in mice. The reason for the earlier assumption came in part because the two problems often occur together: When patients receive strong medications for pain, itching is a frequent side effect. Understanding this separation may lead to more effective treatments for both.
Last year, Zhou-Feng Chen, Ph.D., an investigator at Washington University’s Pain Center, and his team were the first to identify an itch gene. Further experiments with mice have demonstrated that pain signals were not affected when mice were bred without the itch gene, or when its actions were blocked. The gene known as GRPR makes a receptor found in a small group of nerve cells in the spinal cord. In addition to pain and itching, that region of the spinal cord also transmits temperature sensation from the skin to the brain.
“There are two major types of itching. There is histamine-dependent itching caused by bug bites or allergic reactions, which is the kind of itching that can be treated with antihistamine drugs,” explains Chen. “The majority of chronic, severe itching is resistant to antihistamine treatment.” His team thinks that GRPR may be responsible for that type of itching.
The team examined both mice bred with and without GRPR and compared scratching behaviors and the pain-killing effects of morphine. All the mice got relief from mildly painful stimuli, but those without the GRPR gene did not scratch. Next they studied mice treated with a small peptide that interferes with GRPR function. When injected with the GRPR blocker, mice with the gene still got pain relief and did not scratch. This seems to indicate there are separate itch- and pain-related pathways in the spinal cord.
Like mice, humans also have the GRPR gene, so it may be possible to treat chronic pain in humans without causing itching with a GRPR blocker. Chen explains that some GRPR blockers are already in clinical trials for cancer patients with chronic itch. Their next step is to develop a more consistently useful GRPR blocker. Many chronic diseases such as kidney and liver failure have itching as a component. While it is critical to treat the underlying disease, chronic itching greatly impacts quality of life.
Crossing the Blood-Brain Barrier to Reverse Alzheimer’s and Stroke…Like an effective bouncer at a nightclub, the blood-brain barrier (BBB) is there to keep out ‘the wrong sort’ and let in the A-List. Harmful pathogens or substances that might hurt our delicate neural tissue shouldn’t be there. If the wrong sort do manage to get in, the bouncer throws them back out. Dr. William Banks, professor of geriatrics and pharmacological and physiological science at Saint Louis University, says researchers have now found a way to turn off the bouncer when it’s keeping beneficial drugs out of the brain.
He says the problem in treating many diseases of the central nervous system Alzheimer’s, HIV, stroke, is that they can’t get drugs past the BBB and into the brain. A new therapy is showing progress in test tubes and mouse models. The therapy, dubbed PACAP27 (pituitary adenylate cyclase-activating polypeptide), uses a hormone produced by the body that is a general neuroprotector of the brain against insult and injury. “When it can get into the brain, mice with a version of Alzheimer’s got smarter. In the stroke model mice, it reduced the amount of damage caused by the blockage of blood to the brain, as well as improved brain recovery. In the test tube, minute amounts of PACAP27 prevented the AIDS virus from invading. ”
The problem is getting enough of the PACAP27 into the brain long enough for it to have an effect. The bouncer throws it back out when it gets in, so the researchers designed a molecule to temporarily turn off the bouncer. Called an antisense, the molecule allowed the PACAP27 in four times as quickly and for long enough periods and in high enough quantities to have an effect. Researchers found that in the stroke mice, simply using the antisense allowed the PACAP27 hormone naturally existing in the body to effectively treat stroke. The Alzheimer’s mouse models needed both an extra dose of PACAP27 and the antisense to improve learning.
“This research is exciting at several levels,” comments Banks. “We found a therapy to reverse symptoms of Alzheimer’s and stroke in mice, isolated a roadblock that keeps the treatment from getting into the brain, and found a way around that roadblock so the medicine could get into the brain to do its work.” He hopes what they have learned will evolve into therapies for many central nervous system diseases because many of the worst diseases of the 21st century have a big brain component: AIDS, obesity, alcohol addiction and even post-traumatic stress disorder. “We have some great new drugs that should get into the brain but don’t because they are pumped out,” Banks concludes. “Our novel discovery of using an antisense molecule to prevent that mechanism is a promising advance.”
Amazing Voyage of the Smart Pill…When the movie Fantastic Voyage came out in 1966, little did we know that tiny spaceships would one day be able to take a trip through the body (minus the tiny people) to see us from the inside. That day has come.
Miniature cameras and computers in capsule-size pills are already being used to view the gastrointestinal tract from top to bottom as they work their way through the system, just like food. One version widely used in the area for diagnosing GERD (gastroesophageal reflux disease) is the Bravo™ pH monitoring system. Because conditions other than GERD can cause heartburn, it’s important to have a definite diagnosis based on physical exam, symptoms, and the pH level (acid or alkaline) of the esophagus.
With this system, the gastroenterologist places the Bravo capsule into the esophagus, where it is attached by a small piece of tissue held to the tube by suction. The patient is then equipped with a small wireless pager to wear on his belt and goes about his business for 48 hours, eating and drinking normally, during which the capsule transmits pH readings to the pager. After two days, the patient turns in the pager to the physician, who downloads the stored measurements. The capsule then sloughs off the wall of the esophagus and works its way out of the body.
Another iteration of this system is the prototype Intelligent pill, (iPill), designed by Philips Research. This 11 x 26 mm capsule contains a microprocessor, battery, pH sensor, temperature sensor, wireless transceiver, fluid pump and drug reservoir. Not only can it read pH and temperature at different places along the digestive tract, it can dispense medication at critical junctures based on pH reading or under imaging such as an MRI or CT scan. It is designed to be ingested like any gelcap without discomfort to the patient.
Digestive tract disorders such as Crohn’s disease, colitis, and colon cancer have increased in frequency. Crohn’s, in particular, can be impacted by this new technology since it is frequently treated with steroids. Taken systemically, they have unpleasant side effects. But the iPill could possibly deliver the drugs directly to the site of the problem in the intestine without the systemic effects. The capsule can be programed for site-specific drug bursts, progressive release, or multi-site dosing can be loaded into the capsule before it is swallowed. Early tests in the laboratory have shown great accuracy to the system. People testing comes next.
Cooling the Brain During Anesthesia…The effects of anesthesia on human infants and young children have long been debated by neuroscientists. There is growing evidence that exposure to anesthesia drugs during brain development may contribute to behavioral and developmental delays. In two studies with infant mice, Dr. John Olney, senior investigator and John P. Feighner Professor of Neuropsychopharmacology at Washington University School of Medicine, and his team demonstrated that young rodents exposed to alcohol, anesthetics, or anticonvulsants lost large numbers of their brain cells through a process known as neuroapoptosis. The second study suggested that cooling the brain is quite effective in suppressing neuroapoptosis after an infant animal has been exposed to anesthesia.
“It has widely been assumed that the benefits of anesthesia can be achieved without adverse consequences, but that assumption has been called into question in recent years by work from our laboratory and others around the world,” says Olney. The protective effects of cooling most likely can be achieved by either cooling the entire body or applying a cooling helmet to the head. Other studies have indicated that the drug lithium may provide similar protection against damage from anesthesia.
“Before cooling helmets are used with all babies undergoing anesthesia, we still need additional research on both the safety and effectiveness of brain cooling,” Olney notes. “However, immediate brain cooling is currently being used in infants who show signs of severe neurological impairment at birth. Recent studies have shown improvement in survival and cognitive outcomes, and that cooling is well tolerated by newborn infants.”
Olney says that, worldwide, millions of infants and fetuses are exposed to anesthesia each year. Anesthetic drugs are administered not only for surgery but for sedation during certain procedures to hold an infant still or to keep the infant from dislodging IVs or feeding tubes. As the research advances, he sees the possibility that brain cooling, lithium or a combination of the two protective approaches may be shown to improve the cognitive outcome of babies or fetuses exposed to anesthesia.
Brain Implants Yield Information…Contrary to what we’ve always heard about the right side of the brain controlling the left side of the body and vice versa, there are some exceptions. Researchers have found that some functions that are ipsilateral (same-side control). That knowledge is leading to brain implants that may help stroke patients.
The implants, called brain-computer interfaces (BCI), can detect activity on one side of the brain that is linked to specific hand and arm movements on the same side of the body. The hope is that these brain signals can be used to guide motorized assistance devices to restore mobility to partially paralyzed limbs.
The key lies in decoding the actual brain signals and matching them up with specific movements. Dr. Eric Leuthardt, assistant professor of neurosurgery, neurobiology and biomedical engineering at Washington University School of Medicine, was the senior author on a study demonstrating that the same-side control mechanism is separate from the opposite-side signals.
BCIs send brain signals to a computer, which interprets them to control prosthetic devices or other movement. In the past, BCIs were small electrodes implanted into brain tissue to record individual brain cells. Because those electrodes eventually created scarring and ceased working, Leuthardt’s approach is to use a plastic sheet filled with electrodes that rests on the surface of the brain. Besides being able to record many neurons at once, there is no scar formation.
For this study, his team worked with six epilepsy patients who had BCIs installed to locate the area of the brain where the seizures originated for possible surgical removal. The sheet BCIs were left on their brain surfaces for one to two weeks. While they were collecting seizure information, the group had the unique opportunity to study brain activity that could benefit many patients with neurological problems. They asked the BCI patients to do things such as move the right or left hand, say specific words and other cognitive tasks, all the while recording brainwaves. “We were able to identify distinct anatomic locations in the brain where these ipsilateral hand control signals occur,” explains Leuthardt. “Three of our patients could use these signals or opposite-sided hand control signals to move a computer cursor on a screen.”
The research team’s goal is to convert those brain signals to machine commands and give patients control of robotic arms or hands. Stroke patients with partial paralysis usually need surrogate devices. “Working with the epilepsy patients was a great opportunity to learn a lot about the human brain while we are diagnosing and treating the epilepsy,” Leuthardt says. The questions for future study, he says, include how to decode more detailed motor commands, and to what extent function can be restored.
Researchers Identify a Gene for Clubfoot…Clubfoot is one of the most common birth defects, affecting 1 in 1,000 births. It occurs twice as often in boys and more often in the right foot. Scientists have long believed there is a genetic component, and new findings help confirm that. Researchers at Washington University School of Medicine have traced clubfoot to a mutation in a region of chromosome 5, a critical gene for early development of lower limbs. The mutation, called PITX1 has been identified in an extended family of 35, of which 13 were affected.
Christina Gurnett, M.D., Ph.D., and her colleagues visited the family members to examine their lower limbs and take DNA samples. By doing a genome-wide study, they found the PITX1 mutation in all affected family members and three carriers who had no clinical symptoms.
Dr. Matthew Dobbs, an orthopedic surgeon and senior author of the study, treats children with clubfoot and other congenital orthopedic abnormalities. He is excited about the identification of this gene abnormality, which may one day lead to improved genetic counseling, potentially improved treatment, and prevention approaches.
The mutation is dominant, Gurnett says, so about half the children of affected people seem to be at risk for clubfoot or other limb birth defects. Clubfoot is a complex disorder likely to involve several genes, as well as environmental factors. Gurnett hopes to study other genes on chromosome 5, since mutations in nearby genes may also cause limb birth defects.
Currently, Gurnett and her colleagues are studying DNA samples from more than 500 patients with clubfoot treated by Dobbs at St. Louis Children’s Hospital and Shriners Hospital. “We are now evaluating the effects of cigarette smoking on the risk of limb birth defects in mice, as we know this is an environmental risk factor for clubfoot, particularly when combined with a genetic risk factor,” she adds. “Additional clinical and basic laboratory research will be needed to understand the many genes involved, and to devise preventive strategies.” S