PET neuroimaging assesses potential Alzheimer's therapy
PET imaging with the radiotracer 11C-PiB could prove of use for assessing drugs for Alzheimer's disease, according to a study headed up at the University of Turku in Finland. In the Phase 2 study, 28 patients with mild-to-moderate Alzheimer's disease were randomly assigned to receive one of three doses of the investigational drug bapineuzumab (0.5, 1.0 or 2.0 mg/kg) or placebo. Patients received up to six infusions, 13 weeks apart, and had 11C-PiB PET scans at the start of the study and at weeks 20, 45 and 78. Treatment with bapineuzumab for 78 weeks led to a significant reduction in mean 11C-PiB retention compared with placebo, corresponding to roughly a 25% reduction in amyloid-β deposits in the brain (Lancet Neurol. doi: 10.1016/S1474-4422(10)70043-0).
Amyloid plaques are hallmarks of Alzheimer disease that can accumulate in the brain years before the onset of dementia. "Monitoring of the effects of anti-amyloid-β drugs on amyloid-β deposition might be possible with radiotracers that bind to amyloid-β in patients with Alzheimer's disease or those at risk before the onset of clinical decline," said the authors. "This technique offers the opportunity to test more directly the amyloid-β hypothesis by confirming the ability of a particular drug to reduce or prevent amyloid-β accumulation and to assess the effect this has on clinical outcomes."
Latest cardiac CT technology slashes radiation exposure
Research published in the March issue of Radiology reveals that imaging the heart using the latest generation of CT technology exposes patients to up to 91% less radiation than standard helical CT scanning. Many coronary CT angiography exams are currently conducted using 64-detector row CT scanners, which image 4 cm at a time. The latest 320-detector row volume CT scanners can image 16 cm – or the entire length of the heart – in a single rotation and within a single heartbeat.
The study compared the radiation exposure to male and female phantoms during coronary CT angiography using six scan modes, including both 64-row helical and 320-row volume scans. The effective radiation dose was reduced from 35.4 mSv for 64-row helical scanning to 4.4 mSv using optimized 320-row volume scanning (Radiology 254 698). "By imaging the entire heart in one piece, volume scanning eliminates artefacts due to seams or gaps between image sections," explained lead author Andrew Einstein, director of cardiac CT research at Columbia University Medical Center (New York, NY). "Moreover, the X-ray tube is left on for only a brief duration, as little as 0.35 s."
Protons promising for sinonasal cancer treatment
Proton therapy shows encouraging long-term results for patients with locally advanced sinonasal malignancies, according to a study presented at last week's Multidisciplinary Head and Neck Cancer Symposium in Chandler, AZ. The study examined 99 sinonasal-cancer patients treated with proton therapy at Massachusetts General Hospital (Boston, MA). Of the patient group, 67% had surgery prior to irradiation. With a median follow-up of 8.5 years, the local control rates at five and eight years were 87 and 83%, respectively.
"Due to the anatomical location of sinonasal cancers, conventional radiation therapy results in very poor local control and is associated with significant treatment-related toxicity," said principal investigator Annie Chan, a radiation oncologist at Massachusetts General Hospital. "This study showed very encouraging results for these patients and now prospective multi-institutional studies are being planned to further study the use of proton therapy in the treatment of this rare but aggressive malignancy."
Miniature ultrasound device targets osteoarthritis
Ultrasound is often used to relieve muscle and joint pain, but requires treatment in a clinical site. Now, George Lewis - a biomedical engineering graduate student at Cornell University (Ithaca, NY) - has created a miniature ultrasound device that could allow patients to receive such treatment at home instead. The compact device fits into a pocket and sends ultrasound waves deep into muscles via a coin-sized transducer. Lewis's latest prototype transmits low-intensity ultrasound waves from the transducer into the body, and can be kept close to the skin for up to 10 hours.
Lewis recently teamed up with MBA student Bryant Guffey to form a company called ZetrOZ to commercialize the devices. He has also partnered with Cary Reid, a geriatrician at Weill Cornell Medical College's Irving Sherwood Wright Center on Aging, and senior research associate Charles Henderson to prepare the first clinical trial. This will focus on osteoarthritis patients, to determine whether the device can significantly reduce joint pain. Ultimately, Lewis and Guffey hope to demonstrate that the ultrasound device could be used for such groundbreaking therapies as muscle healing and even drug delivery.
Novel MRI sensor provides molecular view of the brain
Functional MRI offers a powerful tool for understanding brain function. However, as it measures blood flow, the technique only provides an indirect readout of neural activity. Now, scientists at MIT (Cambridge, MA) and Caltech (Pasadena, CA) have developed an MRI sensor that responds directly to the neurotransmitter dopamine. To do this, the researchers started with a paramagnetic protein, showed that it could be visualized by MRI, and then evolved it – via rounds of artificial mutation and selection – to bind specifically to dopamine (Nature Biotechnol. doi: 10.1038/nbt.1609).
"We have designed an artificial molecular probe that changes its magnetic properties in response to the neurotransmitter dopamine," said Alan Jasanoff, an associate professor of biological engineering at MIT. "This new tool connects molecular phenomena in the nervous system with whole-brain imaging techniques, allowing us to probe very precise processes and relate them to the overall function of the brain and of the organism. With molecular fMRI, we can say something much more specific about the brain's activity and circuitry than we could using conventional blood-related fMRI." In studies of rats, the sensor effectively detected dopamine in the brain. In its current form, the probe must be injected into the brain. The next challenge is to get it to cross the blood-brain barrier by applying barrier disruption techniques. The MIT team also hope to genetically programme brain cells to express the sensor.
Nanobubbles track down and kill cancer cells
Scientists at Rice University (Houston, TX) have developed a technique for singling out individual diseased cells and destroying them with tiny explosions. The scheme is based on transient plasmonic nanobubbles, which are created when gold nanoparticles delivered to targeted cells are struck by short laser pulses. The researchers note that the nanobubble technology could be used for theranostics, a single process that combines diagnosis and therapy. In addition, because the cell-bursting can be imaged in real time, the technique can be use for post-therapeutic assessment or guidance (Nanotechnology 21 085102).
The researchers, also from the M D Anderson Cancer Center (Houston, TX) and the Lykov Institute of the National Academy of Science of Belarus, tested the approach on leukaemia cells and cells from head-and-neck cancers. They attached antibodies to the nanoparticles to ensure that they only target cancer cells, and found the technique to be effective at locating and killing the cancer cells. A lower laser fluence created small, bright bubbles for non-invasive high-sensitivity imaging. Higher laser powers created large bubbles that burst the cells via disruption of the cellular membrane.