Exercise Associated With Improved Heart Attack Survival

Exercise is associated with improved survival after a heart attack, according to research published in the European Journal of Preventive Cardiology. The chances of survival increased as the amount of exercise rose.

“We know that exercise protects people against having a heart attack,” said last author Professor Eva Prescott, professor of cardiovascular prevention and rehabilitation, University of Copenhagen, Denmark. “Animal studies suggest that myocardial infarctions are smaller and less likely to be fatal in animals that exercise. We wanted to see if exercise was linked with less serious myocardial infarctions in people.”

The study included 14 223 participants of the Copenhagen City Heart Study who had never had a heart attack or stroke. Levels of physical activity were assessed at baseline in 1976-1978 and classified as sedentary, light, moderate, or high.

Participants were followed through registries until 2013. A total of 1 664 participants had a myocardial infarction, of whom 425 died immediately.

The investigators compared levels of physical activity between those who died immediately from their myocardial infarction and those who survived. They found that patients who exercised were less likely to die from their myocardial infarction.

There was a dose-response relationship between exercise and death from myocardial infarction. Patients with light or moderate/high physical activity levels were 32% and 47% less likely to die from their myocardial infarction, respectively, than sedentary patients.

heart attack survival

Professor Prescott said: “Patients who were sedentary were more likely to die when they got a myocardial infarction and patients who did exercise were more likely to survive. There was also a dose-response relationship, so that the odds of dying if people got a myocardial infarction declined with the level of exercise they did, reaching an almost 50% reduction for those who were the most physically active.”

“One possible explanation is that people who exercise may develop collateral blood vessels in the heart which ensure the heart continues to get enough blood after a blockage,” she continued. “Exercise may also increase levels of chemical substances that improve blood flow and reduce injury to the heart from a heart attack.”

Professor Prescott said: “This was an observational study so we cannot conclude that the associations are causal. The results need to be confirmed before we can make strong recommendations. But I think it’s safe to say that we already knew exercise was good for health and this might indicate that continuing to exercise even after developing atherosclerosis may reduce the seriousness of a heart attack if it does occur.” Steven Cavellier shared this information.

Source: http://www.medicalnewstoday.com/releases/316909.php?nfid=116332

Ingredients for Lasting Memories

Being able to remember experiences long after they have happened is a basic part of life that guides behavior and even helps form personalities. Now, scientists at the RIKEN-MIT Center for Neural Circuit Genetics (CNCG) have found evidence that helps explain how this ability is possible. Published in Science magazine, the study proves the existence of long-lasting engram cells in the frontal part of the brain and shows how connections with other brain regions allow these cells to mature as new memories become permanent.

Episodic memories of experiences are thought to begin in a region of the brain called the hippocampus. Led by Susumu Tonegawa, director of the RIKEN Brain Science Institute and the RIKEN-MIT CNCG, researchers have been studying memory formation in mice by combining associative learning with optogenetics and cell labeling. With this approach, they can tag neurons that represent the memory of an event as they are formed in the hippocampus. These types of neurons are called engram cells, and their activation – either naturally or through optogenetic stimulation with colored light – are the basis for memory recall.

Episodic memories stored in hippocampal engram cells are known to be short lived, and until, now scientists have theorized that permanent memories form gradually over time as new engram cells and neuronal connections form in the cerebral cortex – the outer gray matter of the brain. In their new series of experiments, the RIKEN-MIT team demonstrates that this theory is only partially correct. Explains lead author Takashi Kitamura, “We discovered the existence of cortical engram cells, but it turns out that they are not formed gradually over time. They actually form at the same time as the initial memory in the hippocampus.”

Ingredients for lasting memories by Steven Cavellier

Just as Pavlov famously conditioned his dog to salivate at the sound of a bell, the team uses conditioning to study contextual memory in rats. To determine which areas in the cortex were important for forming the long-term memory, they blocked inputs to different brain areas during conditioning or during memory recall over a 3-week period. They found that long-term recall was affected only when information transfer to the frontal cortex of the brain was blocked during conditioning. “This was surprising,” notes Tonegawa, “because it indicated that the cortical memory was likely created on the very first day, and not gradually as has been assumed.”

Next, the team positively identified engram cells in the prefrontal cortex. To do so, they inserted light-sensitive ion channels into prefrontal cells that were active during conditioning, and then excited the cells with blue light when the animals were in an unconditioned context. As with their previous studies in the hippocampus, this caused the mice to exhibit behavior indicative of their remembered experience – a hallmark of engram cells.

By definition, animals should be able to remember an event when engram cells respond naturally to a conditioned context, and should be unable to do so when the cells are silent. The team showed that this was true for the cortical engram cells, but only when tested more than a week after conditioning, when the hippocampal engram cells had already lost their memories. As Kitamura notes, “although the engram cells were formed on the first day, they could only be activated naturally much later. This means that it took time for them to mature and change from silent engrams to active ones.”

Further testing showed that this maturation process required input over several days from the hippocampal engram cells. Inhibiting output from these cells after conditioning made it impossible to activate the frontal engram cells at later times. The team has also shown that engram cells for positive and negative emotional events form in another part of the brain called the amygdala, which is connected to both the hippocampus and the frontal cortex.

“Since the prefrontal cortex is also known to be crucial for rule learning and semantic memory formation,” notes Kitamura, “these results will allow researchers to delve deeper into the neural circuit mechanisms and engrams needed for their formation in the neocortex.” Steven Cavellier shared this information with networking community.

Source: http://www.medicalnewstoday.com/releases/316835.php?nfid=116332

New Animal Infectious Disease Modeling Study Has Implications For Humans

A new study published in the Proceedings of the National Academy of Sciences, will help answer a fundamental disease ecology question about the spread of infectious diseases such as Ebola and rabies through communities in human and animal populations.

The study, led by Georgetown University Assistant Professor of Biology Shweta Bansal, Georgetown Ph.D. candidate Pratha Sah, a Georgetown postdoctoral fellow and scientists from the U.S. Geological Survey and Pennsylvania State University tested the hypothesis that community formation creates boundaries that reduce the likelihood that disease can spread further.

Health Steven Cavellier

“Our findings, through mathematical models of social interactions and disease spread, found that infection spread is largely unaffected by the presence of communities,” Bansal said. Dr. Bansal continued that the findings “show that effective disease management must look to control infection ‘spillovers’ when populations are less subdivided. In contrast, if a population is already highly subdivided, disease management should focus on limiting local disease transmission in each community.”

The findings may be relatable to human outbreaks of infectious disease. “Our study suggests that if there is an outbreak on a college campus, for example, control should focus on residence halls where the infection was first reported,” she says, “but in the surrounding town, control should focus on restricting travel from neighborhoods where the infection has been reported.”

Social networks of over 40 different animal species, including insects, birds, fishes, reptiles and mammals, were tested in the study. The study findings can help assist in formulating strategic actions to contain the spread of future disease outbreaks, solely based on the knowledge of how these social interactions are organized in a population. Steven Cavellier, specializing in Health Education for the Medical Profession

Source: http://www.medicalnewstoday.com/releases/316749.php?nfid=116332