September 2005 Molecule Mediates Metastasis Stopping Sleep Symptom Silences Sympathetic Signals Motor Memories: Total Recall
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New Research Breakthroughs at UHN
Molecule Critical for Cancer Metastasis Drs. Tak Mak (AMDI/CFIBCR/OCI/PMH) and Rama Khokha (OCI/PMH) have discovered that the molecular switch RhoC is crucial for tumour metastasis—the spread of cancer from one part of the body to another. Genes Dev. 2005 Sep 1;19(17):1974-9. Epub 2005 Aug 1. [PubMed abstract] Drs. John Floras and Douglas Bradley (TGRI/TGH) are the first to discover that treating obstructive sleep apnea (OSA) decreases sympathetic activation in patients with heart failure, a condition where the heart is unable to pump enough blood through the body.
The researchers showed that in mice that lack RhoC, cancer cells are less likely to spread, as they are smaller, less mobile and fewer in number than cancer cells from normal mice.
“Notably, the absence of RhoC in mice does not affect other normal cell functions or immune responses,” says Dr. Mak. “This implies that the RhoC pathway may be a suitable target for cancer therapies.”
Research supported by the Canadian Institutes of Health Research and by Amgen Inc.
Institute: AMDI/CFIBCR/OCI/PMH
Division: Stem Cell & Developmental Biology and Signaling Biology
Sleep Apnea Treatment Improves Heart Function
In the early stages of heart failure, increased sympathetic activity helps maintain circulation by causing increased heart rate and contractility; however, over time it often contributes to disease progression.
OSA—a condition where patients stop breathing repeatedly during their sleep—is known to cause increases in sympathetic activation.
“By treating OSA with continuous positive airway pressure, the effects of sympathetic activation were significantly decreased,” says Dr. Floras. “These results merit a longer term outcome trial to determine whether this treatment may improve the prognosis of heart failure patients.”
Research supported by Canadian Institutes of Health Research, Canada Research Chair, Heart and Stroke Foundation, Respironics Inc., and Toronto Rehabilitation Institute.
Institute: TGRI/TGH
Division: Division of Clinical Investigation & Human Physiology
Motor Memories on the Move
New research from Dr. Dianne Broussard’s lab (TWRI/TWH) provides evidence that consolidation—the process of making memories long-term—may involve a change in where memory is stored.
The researchers measured whether animals remembered a learned change in their reflex eye movements after blocking signals to their cerebellar cortex. When the blockade occurred after one hour the animals did not retain the memory; however, when the blockade occurred after three days the animals still remembered.
“Our results suggest that sometime during the first three days after they are formed, motor memories move to a different site in the brain,” says Dr. Broussard. “Next we need to determine whether the change in memory location and consolidation are part of the same process or whether they just happen at the same time.”
Advances in motor memory research may ultimately lead to the development of new therapies for patients with movement disorders.
J Neurosci. 2005 Aug 31;25(35):7979-85. [PubMed abstract]
Research supported by the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada.
Institute: TWRI/TWH
Division: Cell & Molecular Biology