Zebrafish Study Explains Why the Circadian Rhythm Affects Your Health
The circadian rhythm is regulated by a “clock” that reacts to both incoming light and genetic factors.
In an article now being published in the scientific journal Cell Reports, it is demonstrated for the first time that disruption of the circadian rhythm immediately inhibit blood vessel growth in zebra fish embryos.
During experiments with hours-old zebra fish embryos, the researchers manipulated their circadian rhythm through exposing them to lighting conditions varying from constant darkness to constant light. The growth of blood vessels in the various groups was then studied. The results showed that exposure to constant light (1800 lux) markedly impaired blood vessel growth; additionally, it affected the expression of genes that regulate the circadian clock.
"The results can definitely be translated into clinical circumstances. Individuals with disrupted circadian rhythms — for example, shift workers who work under artificial lights at night, people with sleeping disorders or a genetic predisposition — should be on guard against illnesses associated with disrupted blood vessel growth," says Lasse Dahl Jensen, researcher in Cardiovascular Physiology at Linköping University (LiU), and lead writer of the article.
Such diseases include heart attack, stroke, chronic inflammation, and cancer. Disruptions in blood vessel growth can also affect fetal development, women’s reproductive cycles, and the healing of wounds.
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A new study reveals that the brain clock itself is driven, in part, by metabolism, the production and flow of chemical energy in cells. The researchers focused primarily on a phenomenon known as “redox” in tissues of the SCN from the brains of rats and mice.
Redox represents the energy changes of cellular metabolism (usually through the transfer of electrons). When a molecule gains one or more electrons, scientists call it a reduction; when it loses electrons, they say it is oxidized. These redox reactions, the researchers found, oscillate on a 24-hour cycle in the brain clock, and literally open and close channels of communication in brain cells.
“The language of the brain is electrical; it determines what kind of signals one part of the brain sends to the other cells in its tissue, as well as the other parts of the brain nearby,” said University of Illinois cell and developmental biology professor Martha Gillette, who led the study.
“The fundamental discovery here is that there is an intrinsic oscillation in metabolism in the clock region of the brain that takes place without external intervention. And this change in metabolism determines the excitable state of that part of the brain.”
The new findings alter basic assumptions about how the brain works, Gillette said.
“Basically, the idea has always been that metabolism is serving brain function. What we’re showing is metabolism is part of brain function,” she said. “Our study implies that changes in cellular metabolic state could be a cause, rather than a result, of neuronal activity.”
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The connections between the rising rates of chronic disease and the production and consumption of modern foods can no longer be ignored. Our food supply is not healthy, nor is it sustainable. It has changed so dramatically that we have yet to adapt to the changes. Our food supply has been completely adulterated over the past few decades alone, more drastically than during any other time in history.
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Vanderbilt University researchers studying interventions for adolescents and young adults with autism are reporting that there is insufficient evidence to support findings, good or bad, for the therapies currently used.
The researchers systematically screened more than 4,500 studies and reviewed the 32 studies published from January 1980 to December 2011 on therapies for people ages 13 to 30 with autism spectrum disorders. They focused on the outcomes, including harms and adverse effects, of interventions, including medical, behavioral, educational and vocational.
• Some evidence revealed that treatments could improve social skills and educational outcomes such as vocabulary or reading, but the studies were generally small and had limited follow-up.
• Limited evidence supports the use of medical interventions in adolescents and young adults with autism. The most consistent findings were identified for the effects of antipsychotic medications on reducing problem behaviors that tend to occur with autism, such as irritability and aggression. Harms associated with medications included sedation and weight gain.
• Only five articles tested vocational interventions, all of which suggested that certain vocational interventions may be effective for certain individuals, but each study had significant flaws that limited the researchers’ confidence in their conclusions.
A Systematic Review of Vocational Interventions for Young Adults With Autism Spectrum Disorders
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Britain’s first bionic veteran has a new brain-controlled robotic arm that is transforming his life.
Andrew Garthwaite, 25, had his right arm blown clean off by a rocket-propelled grenade during a firefight with the Taliban in Afghanistan in September 2010. In January he had the state-of-the-art limb wired to his nervous system during a six-hour operation in Vienna, Austria.
Now he is getting to grips with his new body part and is able to ride his motorcycle and drive a car again. Mr Gathwaite, who lives with his new wife Kailey, also 25, in South Shields, Tyneside, said:
'It's been incredible. I thought I might never be the same. But my life is starting to get back to normal - I'm on my motorbike and I'm back in a car. I can do things that I never thought I would have been able to do'.
Filed under bionic arm bionic implants brain neuroscience prosthetics robotics science technology nervous system
Harvard scientists have created a type of cyborg tissue by embedding a three-dimensional network of functional, biocompatible, nanoscale wires into engineered human tissues.
The research addresses a concern that has long been associated with work on bioengineered tissue: how to create systems capable of sensing chemical or electrical changes in the tissue after it has been grown and implanted. The system might also represent a solution to researchers’ struggles in developing methods to directly stimulate engineered tissues and measure cellular reactions.
The process of building the networks is similar to that used to etch microchips. Beginning with a two-dimensional substrate, researchers laid out a mesh of organic polymer around nanoscale wires, which serve as the critical sensing elements. Nanoscale electrodes, which connect the nanowire elements, were then built within the mesh to enable nanowire transistors to measure the activity in cells without damaging them. Once completed, the substrate is then dissolved, leaving researchers with a netlike sponge, or a mesh, that can be folded or rolled into a host of three-dimensional shapes. Finally, the networks are porous enough to allow seeding them with cells and encourage those cells to grow in 3-D cultures.
Using heart and nerve cells, the Harvard research team successfully engineered tissues containing embedded nanoscale networks without affecting the cells’ viability or activity. Using the embedded devices, the researchers were then able to detect electrical signals generated by cells deep within the tissue, and to measure changes in those signals in response to cardio- or neuro-stimulating drugs.
Filed under artificial tissue neuroscience robotics science tissue technology medical implants nanoscale networks
Behavioral test shows promise in predicting future problems with alcohol
By administering a simple behavioral test, Yale researchers were able to predict which mice would later exhibit alcoholism-related behaviors such as the inability to stop seeking alcohol and a tendency to relapse, the scientists report in the Aug. 26 issue of the journal Nature Neuroscience.
"We are trying to understand the neurobiology underlying familial risk for alcoholism," said Jane Taylor, the Charles B.G. Murphy Professor of Psychiatry and professor of psychology at the Yale School of Medicine and senior author of the study. "What is encouraging about this study is that we have identified both a behavioral indicator and a molecule that explains that risk."
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Are you a morning lark or a night owl? Scientists use that simplified categorization to explain that different people have different internal body clocks, commonly called circadian clocks. Sleep-wake cycles, digestive activities, and many other physiological processes are controlled by these clocks. In recent years, researchers have found that internal body clocks can also affect how patients react to drugs. For example, timing a course of chemotherapy to the internal body time of cancer patients can improve treatment efficacy and reduce side effects.
Round the clock. Tracking the levels of 50 hormones and amino acids in blood samples (shown by ribbons) reveals a body’s internal time. Credit: PNAS
But physicians have not been able to exploit these findings because determining internal body time is, well, time consuming. It’s also cumbersome. The most established and reliable method requires taking blood samples from a patient hourly and tracking levels of the hormone melatonin, which previous research has tied closely to internal body time.
Now a Japanese group has come up with an alternative method of determining internal body time by constructing what it calls a molecular timetable based on levels in blood samples of more than 50 metabolites—hormones and amino acids—that result from biological activity. The researchers established a molecular timetable based on samples from three subjects and validated it using the conventional melatonin measurement. They then used that timetable to determine the internal body times of other subjects by checking the levels of the metabolites in just two blood samples from each subject per day.
Having such a timetable could allow doctors to synchronize drug delivery to internal body time, the team reports online today in the Proceedings of the National Academy of Sciences. “Usually personalized medicine is focusing on genetic differences, but there are also temporal differences [among patients]. That will be the next step in personalized medicine,” says systems biologist Hiroki Ueda of the RIKEN Center for Developmental Biology in Kobe, Japan, who heads the research group.
"In principle, the method holds great promise as a way of replacing the cumbersome melatonin assay," says Steven Brown, a molecular biologist at the University of Zurich in Switzerland. "The authors show in a small-scale, well-controlled experiment that they are able to predict internal body time within a precision frame of 3 hours," says Urs Albrecht of the University of Fribourg in Switzerland. Both researchers say further work will be necessary to make the technique more practical and more widely applicable, and Ueda agrees. The experimental subjects were all young men, and different molecular timetables are likely needed for women and for people of different ages. He would also like to improve the precision and make it reliable with just one blood sample per day.
Source: ScienceNOW
Filed under science neuroscience psychology circadian clocks biology melatonin
A new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute shows that a two-hour exposure to electronic devices with self-luminous “backlit” displays causes melatonin suppression, which might lead to delayed bedtimes, especially in teens.
The research team, led by Mariana Figueiro, associate professor at Rensselaer and director of the LRC’s Light and Health Program, tested the effects of self-luminous tablets on melatonin suppression. In order to simulate typical usage of these devices, 13 individuals used self-luminous tablets to read, play games, and watch movies.
The actual melatonin suppression values after 60 minutes were very similar to those estimated using a predictive model of human circadian phototransduction for one-hour light exposures. “Based on these results, display manufacturers can use our model to determine how their products could affect circadian system regulation,” said Figueiro.
The results of this study, together with the LRC predictive model of human circadian phototransduction, could urge manufacturers to design more “circadian-friendly” electronic devices that could either increase or decrease circadian stimulation depending on the time of day — reducing circadian stimulation in the evening for a better night’s sleep, and increasing in the morning to encourage alertness.
Filed under science technology neuroscience brain circadian phototransduction melatonin suppression electronic devices
