Magnets Guide Brain Surgery
Treating tumors or aneurysms hidden deep inside the brain is a difficult task that can result in damage to healthy parts of the brain. Sometimes, for example, the only way to reach a point on the brain’s interior is to slice or poke through healthy tissue on the periphery, a process that can produce irreversible damage.
Researchers at the Washington University School of Medicine in St. Louis have devised a clever way around the problem, using an array of superconducting magnets to guide a small magnet into the desired spot in the brain, avoiding healthy brain as it enters. The mobile magnet pulls in a tube through which surgeons can then perform necessary manipulations on the target tissue.
The system was used for the first time Dec. 17 by Dr. Ralph Dacey to biopsy a brain tumor in a 31-year-old man at Barnes-Jewish Hospital in St. Louis. Dacey has permission to test it on four other patients in the first phase of gaining approval from the Food and Drug Administration.
To perform the surgery, Dacey used sophisticated imaging techniques to map the patient’s brain, determining where the tumor lay and a safe path to reach it.
The patient’s head was then placed in a titanium cradle surrounded by six superconducting magnets. Sitting at a computer console, Dacey then varied the strengths of the magnets to slowly guide a small permanent magnet to the site. The magnet was attached to a guide wire covered by a plastic catheter slightly fatter than a strand of spaghetti.
When the mobile magnet reached the site, it was withdrawn with the guide wire, leaving the catheter in place to guide tools into the area to retrieve a tissue sample.
Dacey said the device could also be used to insert electrodes into the brain for measuring brain activity and to deliver drugs to precise areas for therapy.
Violence Not Always Passed On to Children
An aggressive or violent parent does not necessarily produce an aggressive or violent child--at least as far as females are concerned--according to researchers from the University of North Carolina at Chapel Hill. Psychologist Robert B. Cairns and his col leagues studied 57 pairs of mothers and offspring over a 17-year period, analyzing their positive and negative behaviors every year.
They report in the December issue of Developmental Psychology that children whose mothers were aggressive or violent during childhood were no more likely themselves to be aggressive or violent than were children whose mothers behaved more normally.
They did, however, find a strong link in academic performance. Mothers who performed poorly in school tended to produce children who also earned poor grades.
Cairns speculated that the children may be favorably influenced by their fathers and grandparents, or that girls who were violent when they were in school mature when they become mothers, and hence may not pass on violent tendencies to their children.
Vitamin A Gives Mice Brains a Boost
Vitamin A may promote learning ability, according to researchers from the Salk Institute for Biological Sciences in La Jolla. An estimated 190 million children worldwide are thought to have a vitamin A deficiency, and this research suggests that the deficiency could have a significant impact on their learning abilities both in school and later in life.
Neuroscientist Ronald Evans and his colleagues studied mice that had been genetically engineered so that the brain cells that controlled learning could no longer take up vitamin A. The team reports in the January issue of Neuron that the mice developed normally, but performed much more poorly than ordinary mice in standard intelligence tests. Further studies suggested that the vitamin helps fine-tune connections between brain cells that are crucial in forming memories.
Pesticide Exposure May Alter Hormone Levels
Men exposed to pesticides on the job have altered sex hormone levels, suggesting pesticide-induced damage to the testicles, according to Harvard researchers. Dr. Chantana Padungtod and colleagues studied men working at a Chinese factory that produced organophosphate pesticides, such as ethylparathion.
They report in the December Journal of Occupational and Environmental Medicine that men at the factory had unusually high levels of female sex hormones, such as estrogen, and lower-than-normal levels of such male hormones as testosterone. The men also had reduced sperm counts.
Cancer-Protecting Protein Identified
Researchers at the University of Maryland Medical Center have discovered why some breast and other cancers become resistant to the drugs normally used in treatment.
Dr. L. Austin Doyle and his colleagues reported in Tuesday’s Proceedings of the National Academy of Sciences that they had discovered a protein which pumps the drugs out of the cancer cells, allowing the cells to avoid the drugs’ lethal effects. Similar pumps have been found in other cancer cells, Doyle said, but the new one is smaller and more active. He hopes to identify drugs that could block the pumping activity, thereby making the cancer less resistant to chemotherapy.
Gene Mutation Speeds Growth of Cancer Cells
A UCLA researcher has identified a gene mutation that accelerates the growth of prostate cancer cells, a discovery that could help in the development of drugs to combat the disease.
Dr. Charles Sawyers and his colleagues reported in the Proceedings of the National Academy of Sciences that mutations in a gene called PTEN cause cells to be flooded with growth-promoting chemicals, causing them to multiply and form tumors. Their studies show that about half of prostate cancer victims have the gene mutation leading to uncontrollable growth.
Sawyers speculated that it should be possible to produce drugs that block this pathway. Herceptin, a breast cancer drug developed at UCLA, works in just that fashion, blocking the effects of a different growth-promoting mutation. About 184,500 men will develop prostate cancer this year and 40,000 will die of it.
