Unraveling Alzheimer's: Clues may be found visualizing plaques in human brain, mad cow–type diseases

IMPY tracer developed by University of Pennsylvania researchers detects amyloid plaques in Alzheimer's and animal prion diseases, say researchers at SNM's 53rd Annual Meeting June 3–7 in San Diego

SAN DIEGO, Calif.--An exciting new tracer allows visualization of abnormal protein deposits--called amyloid plaques--in human diseases like Alzheimer's and Creutzfeldt-Jakob and in prion diseases in animals like scrapie (similar to mad cow disease), according to researchers at the University of Pennsylvania and CHRU Tours in France. Their results were presented June 3–7 during SNM's 53rd Annual Meeting in San Diego.

"This amyloid tracer IMPY--which detects amyloid plaques in the human brain--provides an excellent starting point for parallel research in humans and animals," said Denis Guilloteau, a biophysics professor and radiopharmacist in the nuclear medicine department of the Centre Hospitalier Universitaire Tours (CHRU) in France. "With IMPY, we were able to visualize abnormal protein in both neurodegenerative diseases--Alzheimer's and scrapie--and this could provide new directions for future research," he added. There are similarities between the loss of brain function in prion diseases and in Alzheimer's disease, and an understanding of prion diseases will add to the understanding of what happens to the brain with Alzheimer's disease, explained the co-author of "IMPY, a Beta-Amyloid Imaging Probe for Prion Detection." In addition, the tracer may be used for research in the veterinary field, he noted.

Alzheimer's disease is a progressive, irreversible brain disorder with no known cause or cure. Symptoms may include memory loss, confusion, impaired judgment, disorientation and loss of language skills. More than 4.5 million Americans are believed to have Alzheimer's disease, and by 2050, the number could increase to 13.2 million.

Prions are abnormal, transmissible agents--with no DNA--that are able to induce abnormal folding of normal cellular prion proteins in the brain, leading to brain damage and the characteristic signs and symptoms of the disease. Prions cause a number of rare progressive neurodegenerative disorders that affect both humans and animals, and the diseases are usually rapidly progressive and always fatal. Creutzfeldt-Jakob disease is a rare, degenerative human brain disorder. Scrapie is a degenerative disease that affects the nervous systems of sheep and goats, and it is related to mad cow disease. Currently, a brain autopsy is necessary to obtain a definite diagnosis for Alzheimer's and Creutzfeldt-Jakob. Guilloteau noted that investigating the prion animal diseases could form a model for future research in human disease. "It is important to study human neurodegenerative diseases and animal prion diseases in parallel," he said.

Developing molecular agents such as IMPY may be useful for diagnosis and monitoring the progression of Alzheimer's, noted Guilloteau. "The beta-amyloid tracer--developed by University of Pennsylvania researchers--is a very promising tool that may be used to discern an early diagnosis of Alzheimer's with single photon emission computed tomography (SPECT), an imaging method available in many hospitals," he added.

In the study, researchers used radioiodinated IMPY to bind to prion deposits in infected mice brain sections. Autoradiography, a procedure where an image is produced on photographic film by the radiation from a radioactive substance, showed a good visualization of these prion deposits, said Guilloteau. Major accumulations of radioactivity were seen in the cortex, colliculus, hippocampus, thalamus, cerebellum and pons. "Additional work needs to focus on the progression of disease in our animal model in vivo, and we must correlate the images with clinical symptoms," he added.

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Abstract: P. Song, J. Vergote and D. Guilloteau, all with nuclear medicine, CHRU Tours, Tours, France; B. Serge, H. LeRoux and P. Sarradin, INRA, Nouzilly, France; and M. Kung and H. Kung, radiology department, University of Pennsylvania, Philadelphia, Pa., "IMPY, a Beta-Amyloid Imaging Probe for Prion Detection," SNM's 53rd Annual Meeting, June 3–7, 2006, Scientific Paper 383.

About SNM

SNM is holding its 53rd Annual Meeting June 3–7 at the San Diego Convention Center. Research topics for the 2006 meeting include molecular imaging in clinical practice in the fight against cancer; the role of diagnostic imaging in the management of metastatic bone disease; metabolic imaging for heart disease; neuroendocrine and brain imaging; new agents for imaging infection and inflammation; and an examination of dementia, neurodegeneration, movement disorders and thyroid cancer.

SNM is an international scientific and professional organization of more than 16,000 members dedicated to promoting the science, technology and practical applications of molecular and nuclear imaging to diagnose, manage and treat diseases in women, men and children. Founded more than 50 years ago, SNM continues to provide essential resources for health care practitioners and patients; publish the most prominent peer-reviewed journal in the field; host the premier annual meeting for medical imaging; sponsor research grants, fellowships and awards; and train physicians, technologists, scientists, physicists, chemists and radiopharmacists in state-of-the-art imaging procedures and advances. SNM members have introduced--and continue to explore--biological and technological innovations in medicine that noninvasively investigate the molecular basis of diseases, benefiting countless generations of patients. SNM is based in Reston, Va.; additional information can be found online at http://www.snm.org.


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