Posts Tagged ‘Yasemin Saplakoglu’

By Yasemin Saplakoglu

The newest neuron has been named the “rosehip neuron,” thanks to its bushy appearance. The brain cell, with its unique gene expressions, distinctive shape and diverse connections with other neurons, has not been described before and, what’s more, it isn’t present in neuroscientists’ favorite subject: mice.

“It’s very bushy,” said Trygve Bakken, one of the lead authors of the paper and senior scientist at the Allen Institute for Brain Science in Seattle. Neurons have long branches called dendrites that receive signals from other neurons. In the rosehip cells, these dendrites are “very compact with lots of branch points, so it kind of looks a little bit like a rosehip,” Bakken told Live Science. (Rosehips are a type of fruit produced by rose plants.)

Also adding to the rosehip appearance are the large bulbs at the end of their axons that release neurotransmitters or chemical signals to other neurons, Bakken added.

The new finding is the result of a collaboration between Bakken and his team and researchers at the University of Szeged in Hungary. Both teams independently identified the distinctive-looking neurons and, when the teams learned they were looking at the same thing, they decided to work together, Bakken said.

The researchers at the Allen Institute documented the strange new neuron by examining the brain tissue of two deceased middle-age men. When the researchers looked at the genes of the rosehip neuron in this post-mortem tissue, they found that the neurons acted differently. “There are a number of genes that are turned on just in that cell and not in other[s],” Bakken said

Meanwhile, the team in Hungary further documented the rosehip neuron by studying the electrical activity and shapes of neurons in brain tissue that had been removed from people’s brains during surgery and kept alive in a solution.

A rare neuron

One reason rosehip neurons eluded neuroscientists for so long is likely because the cells are so rare in the brain, Bakken said. Another reason, he added, is because human brain tissue is difficult for scientists to obtain for study. Indeed, in the study, the researchers examined only one layer of the brain. It’s possible, however, that rosehip neurons could be found in other layers, too, Bakken said.

Specifically, the researchers found that the rosehip neurons make up about 10 percent of the first layer of the neocortex — the most recently evolved part of the cortex that’s involved in sight and hearing. They also found that rosehip neurons connect to neurons called pyramidal cells, a type of excitatory neuron that makes up two-thirds of all the neurons in the cortex, according to Cell.

The full extent of the rosehip neurons relationship to the pyramidal neurons is unclear, but the researchers did find that the rosehip neurons act as inhibitory neurons, or those that restrain the activity of other neurons. “They have the potential to sort of put the brakes on the excitability” of pyramidal neurons, Bakken said. But as to how this influences the brain’s behavior, “we don’t really know yet,” he added.

Absent in mice

All mammals have a cortex, and within it a neocortex, Bakken said. But there are about “a thousand times more cells in the human cortex compared to the mouse,” he said. In other words, it makes up a much bigger part of our brain than it does a mouse’s. So then, perhaps it’s not surprising that the team didn’t find any genetic hint of rosehip neurons in mice.

“Finding cell types that are uniquely human… helps our understanding of the physiological differences that under[lie] our higher cognitive abilities and may better inform upon treatment strategies for brain-related disorders,” said Blue B. Lake, an assistant project scientist in the bioengineering department at the University of California, San Diego who was not part of the study.

The absence of the rosehip neuron in mice brains might serve as a cautionary reminder that the results of some brain studies done on rats can’t be translated to humans, the researchers said.

“Mice have been a wonderful model organism for understanding how brains work in general and can help us understand how human brains work,” Bakken said. “But I think finding a part of that circuit that is not seen in a mouse that points to needing to study actual human tissue.”

There are enough parts of the brain conserved among mice, humans and other mammals that people can make “inferences about things we learn in the mouse and sort of, at least, hypothesize that something similar is likely to be happening in the human brain,” Bakken said. But, sometimes things present in human brains are “just not there” in mouse brains.

Advertisements

By Yasemin Saplakoglu

Drinking a cup of tea or eating a handful of berries a day may help protect against heart disease, a new study suggests.

The research, presented November 10 at the American Heart Association’s Scientific Sessions annual meeting, found that daily consumption of small amounts of flavonoids — compounds found in berries, tea, chocolate, wine and many other fruits and plants — was associated with a lower risk of heart disease.

This association (which is not to be confused with a cause-and-effect finding) is not new; previous research has also found a link between flavonoids and heart disease risk. But the new study — one of the largest done to date — adds stronger evidence to the idea that flavonoids may protect the heart, said co-lead study author Nicola Bondonno, a postdoctoral researcher at the School of Biomedical Science at the University of Western Australia.

In the study, Bondonno and her team analyzed data from nearly 53,000 people who had participated in the long-running Danish Diet, Cancer and Health Study, which began in the 1990s. At the beginning of that study, participants filled out a questionnaire with information about what types of foods they ate and how often they ate them. The researchers then tracked the participants’ health for more than two decades.

After a 23-year follow-up period, around 12,000 of the participants had developed some sort of heart condition.

The researchers found that people who reported eating around 500 milligrams or more of flavonoids daily had a lower risk of developing ischemic heart disease (where the heart’s major blood vessels are narrowed, reducing blood flow to the heart), stroke and peripheral artery disease (where blood vessels in the body are narrowed, reducing blood flow throughout the body). This association was the greatest for the latter, the researchers found.

Bondonno noted that 500 mg of flavonoids is “very easy to eat in one day.” You would get that amount of flavonoids from “a cup of tea, a handful of blueberries, maybe some broccoli,” she said. They also found that, on average, it didn’t make too much of a difference how much more flavonoids healthy people consumed once they passed the 500 mg/day threshold.

The reason flavonoids could have a protective role against heart disease is because of their anti-inflammatory properties, Bondonno told Live Science. Inflammation is a risk factor for heart disease, she said.

The researchers noted that the association between flavonoids and reduced heart disease risk varied for different groups of people. The link between flavonoids and reduced risk of heart disease in smokers, for example, wasn’t observed at 500 mg of flavonoids a day; rather, smokers needed to eat more flavonoids for the link to be apparent. Similar results were seen in people who drank alcohol and in men. However, it was in these three groups that the researchers found that flavonoid intake was associated with the greatest reduction in risk.

In their analysis, Bondonno and her team made sure to take people’s whole diets into consideration, because people who tend to eat lots of fruits and vegetables (and in turn, consume a lot of flavonoids), tend to have better diets in general, eating more fiber and fish and less processed food, which are all “associated with heart disease,” Bondonno said. When they adjusted for these diets in their report, they found that the association between flavonoid intake and reduced heart disease risk was still there, but a bit weaker. In other words, flavonoids may not play as big a role in heart disease risk as a healthy diet would in general.

Further, the study was conducted only in Danish people, and though these results shouldn’t be extrapolated, “these kinds of associations have been seen in other populations,” Bondonno said.

The findings have not yet been published in a peer-reviewed journal.

https://www.livescience.com/64060-flavonoids-heart-health.html