Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

PET/MRI scans may help unravel mechanisms of prenatal drug damage

07.02.2005


Scientists have demonstrated a new way to assess the potentially damaging effects of prenatal drug exposure--a technique that could also be used to monitor a fetus’s response to therapeutic drugs--using sophisticated, noninvasive medical imaging tools. Scientists at the U.S. Department of Energy’s Brookhaven National Laboratory, whose findings are reported in the February issue of the Society of Nuclear Medicine’s Journal of Nuclear Medicine, used positron emission tomography (PET) combined with magnetic resonance imaging (MRI) to track the uptake and distribution of trace amounts of cocaine in pregnant monkeys and found significant differences in where and how fast the drug accumulates in maternal and fetal organs.



"Understanding how drugs are transferred between a mother and her fetus during pregnancy may help us unravel the mechanisms of the drug’s damaging effects on unborn children," said SNM member Helene Benveniste, M.D., Ph.D., chair of Brookhaven’s medical department in Upton, N.Y., and lead author of the paper, "Maternal and Fetal 11C-Cocaine Uptake and Kinetics Measured In Vivo by Combined PET and MRI in Pregnant Nonhuman Primates."

"While studies that follow human drug abusers and their children over decades provide valuable information, animal studies can more quickly provide clues to the underlying mechanisms of damage and suggest ways to test new treatment or prevention strategies," said Benveniste.


The imaging tools could also be used to assess the effects of therapeutic drugs, such as administering synthetic narcotics to pregnant women following surgical procedures performed on fetuses in utero. "Following such surgeries, which are becoming more common to correct congenital malformations, the mother is treated with narcotics for pain--and anesthesiologists are relying on the mother transferring the pain medication to the fetus via the placenta. But we actually do not know if what we give is sufficient to ’satisfy’ the pain level of the fetus," said Benveniste, who is also a professor of anesthesiology at Stony Brook University.

Though other scientists have attempted to use PET to noninvasively monitor maternal-fetal drug exchange and pharmacokinetics (how quickly a drug is taken up and distributed among the body’s organs), the PET technique alone did not provide adequate anatomical detail of the tiny fetal organs. The current study combined PET with high-resolution magnetic resonance imaging (MRI) to track cocaine pharmacokinetics down to the level of the placenta and individual regions of the fetal brain.

"The MRI images, which have the necessary detail, served as a high-resolution anatomical template onto which we ’overlaid’ the PET pharmacokinetic data using sophisticated computer techniques," Benveniste said. "The resulting images gave us the best of both worlds and allowed us to look at cocaine uptake and distribution in the mother and fetus simultaneously," she added.

The animals were anesthetized prior to scanning. MRI scans were performed first, followed by PET. For the PET study, each animal was injected with a trace quantity of cocaine--less than 10 micrograms, which is not enough to cause pharmacological effects. The injected cocaine had previously been "labeled," or "tagged," with a short-lived radioactive form of carbon (carbon-11). This radiotracer emits a signal that is picked up by the PET scanner, which takes snapshots of the tracer’s location over time to show how much and how quickly the cocaine (and/or the metabolic byproducts that retain the carbon-11) enters and clears the various organs. The radiotracer decays and completely clears from the animal’s body in about two hours. After the procedure, the animals were returned to their social colony to deliver their offspring.

The combined images show that cocaine and/or its labeled metabolites readily cross the placenta. But the cocaine uptake distribution pattern observed in the fetus was very different from that of the mother. For example, mothers showed rapid uptake and clearance of the drug in the heart, kidneys and lungs, with slower uptake in the liver and brain. In the fetus, cocaine accumulated at the highest levels in the liver (due to the unique anatomy of fetal circulation) and to a lesser extent in the brain.

"While the uptake of the tracer into the fetal brain is lower and slower than in the mother’s brain, a measurable quantity of cocaine and/or its labeled metabolites does accumulate in the fetal brain, particularly in the striatum, where cocaine is known to bind to cell-surface receptors that result in a euphoric response," Benveniste said.

The high uptake of radiolabeled cocaine in the placenta is also particularly relevant, the researchers said, because cocaine is known to constrict blood vessels in the placenta. It may be that this constriction of placental blood flow is one of the mechanisms underlying the harmful effects of cocaine exposure during pregnancy.

The research was funded by the Office of Biological and Environmental Research within the Department of Energy’s Office of Science and the National Institute on Drug Abuse. The monkeys were obtained from the Primate Laboratory, department of psychiatry, at the State University of New York (SUNY) Downstate, Brooklyn.

"Maternal and Fetal 11C-Cocaine Uptake and Kinetics Measured In Vivo by Combined PET and MRI in Pregnant Nonhuman Primates" was written by Benveniste; Joanna S. Fowler, Ph.D., William Rooney, Ph.D., and SNM member Yu-Shin Ding, Ph.D., all with Brookhaven’s chemistry department; Angela L. Baumann, M.D., Brookhaven’s medical department and the anesthesiology department of Stony Brook University; Daryn H. Moller, M.D., anesthesiology department, Stony Brook University; Congwu Du, Ph.D., Brookhaven’s medical department; Walter Backus, M.D., anesthesiology department, Stony Brook University; Jean Logan, Ph.D., and Pauline Carter, RN, both with Brookhaven’s chemistry department; Jeremy D. Coplan, M.D., psychiatry department, SUNY Downstate, Brooklyn; Anat Biegon, Ph.D., Brookhaven’s medical department; Leonard Rosenblum, Ph.D., and Bruce Scharf, DVM, both with the psychiatry department, SUNY Downstate, Brooklyn; John S. Gatley, Ph.D., Brookhaven’s medical department; and SNM member Nora D. Volkow, M.D., National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Md.

Maryann Verrillo | EurekAlert!
Further information:
http://www.snm.org

More articles from Health and Medicine:

nachricht TSRI researchers develop new method to 'fingerprint' HIV
29.03.2017 | Scripps Research Institute

nachricht Periodic ventilation keeps more pollen out than tilted-open windows
29.03.2017 | Technische Universität München

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>