Category: Biology (page 15 of 63)

dopamine explained

 

Dopamine

The structure of dopamine

Last week on Slate, Bethany Brookshire explains the neurotransmitter dopamine and how it effects many different chemical processes:

What is dopamine? Dopamine is one of the chemical signals that pass information from one neuron to the next in the tiny spaces between them. When it is released from the first neuron, it floats into the space (the synapse) between the two neurons, and it bumps against receptors for it on the other side that then send a signal down the receiving neuron. That sounds very simple, but when you scale it up from a single pair of neurons to the vast networks in your brain, it quickly becomes complex. The effects of dopamine release depend on where it’s coming from, where the receiving neurons are going and what type of neurons they are, what receptors are binding the dopamine (there are five known types), and what role both the releasing and receiving neurons are playing.

It has far more roles in the brain to play. For example, dopamine plays a big role in starting movement, and the destruction of dopamine neurons in an area of the brain called the substantia nigra is what produces the symptoms of Parkinson’s disease. Dopamine also plays an important role as a hormone, inhibiting prolactin to stop the release of breast milk. Back in the mesolimbic pathway, dopamine can play a role in psychosis, and many antipsychotics for treatment of schizophrenia target dopamine. Dopamine is involved in the frontal cortex in executive functions like attention. In the rest of the body, dopamine is involved in nausea, in kidney function, and in heart function.

the effects of bad science

Vaccination

A new epidemic of measles has broken out in Wales. Vaccination rates fell after a paper linking the vaccine to autism was published in the 1998. The paper was later proven to be fraudulent. NPR reports:

More than 1,200 people have come down with measles so far this year, following nearly 2,000 cases in 2012. Many of the cases have been in Wales.

Childhood vaccination rates plummeted in Great Britain after a 1998 paper by Dr. Andrew Wakefield claimed that the vaccine for measles, mumps and rubella had caused autism in a dozen children. That study has since been proven , but it fueled fears about vaccine safety in Great Britain and the United States.

“This is the legacy of the Wakefield scare,” Dr. David Elliman, spokesman for the Royal College of Pediatrics and Child Health, told The Associated Press.

Most of the measles cases have been in children and teenagers between the ages of 10 and 18, according to British health officials. In that age group, vaccination rates dropped below 50 percent in some parts of England after the Wakefield paper was published.

manufactured burgers

in vitro meat

In vitro meat. Image from the New York Times

Last week, the New York Times brought news of an upcoming burger taste test in London. Scientists have been hard at work developing new lab grown meat that they hope to turn into hamburger patties.

Dr. Post, one of a handful of researchers in the field, has made strides in developing cultured meat through the use of stem cells — precursor cells that can turn into others that are specific to muscle, for example — and techniques adapted from medical research for growing tissues and organs, a field known as tissue engineering. (Indeed, Dr. Post, a physician, considers himself first and foremost a tissue engineer, and about four-fifths of his time is dedicated to studying how to build blood vessels.)

Yet growing meat in the laboratory has proved difficult and devilishly expensive. Dr. Post, who knows as much about the subject as anybody, has repeatedly postponed the hamburger cook-off, which was originally expected to take place in November.

His burger consists of about 20,000 thin strips of cultured muscle tissue. Dr. Post, who has conducted some informal taste tests, said that even without any fat, the tissue “tastes reasonably good.” For the London event he plans to add only salt and pepper.

But the meat is produced with materials — including fetal calf serum, used as a medium in which to grow the cells — that eventually would have to be replaced by similar materials of non-animal origin. And the burger was created at phenomenal cost — 250,000 euros, or about $325,000, provided by a donor who so far has remained anonymous. Large-scale manufacturing of cultured meat that could sit side by side with conventional meat in a supermarket and compete with it in price is at the very least a long way off.

The scientists hope to be able to preview the meat in a taste test sometime this year.

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