Posted by Mike on November 27, 2008 under 1. Info Collection | 
Does Tryptophan from turkey meat make you sleepy? [A Blog Around The Clock]: “
It’s Thanksgiving tomorrow and the question (of the title of this post) pops up on the internets again. See SciCurious and Janet for the latest local offerings.
Short answer: we don’t know.
But there is endless speculation about it, each taking into account bits and pieces of information that we know about tryptophan and related physiology. The hypotheses tend to focus on:
a) Tryptophan itself, i.e., how it can get from food, through the intestine, through the bloodstream, to the brain and what it would do once there.
b) Serotonin, as a product of tryptophan metabolism, and how it can be produced (and where - in the brain or somewhere else) and what it would do once there.
I like to post and re-post, around this time of year, the third alternative, taking into account that serotonin is precursor of melatonin, that all the enzymatic machinery needed for transformation of tryptophan to melatonin operates in the intestine itself, that melatonin (unlike tryptophan) easily crosses the blood-brain barrier, and that melatonin does have some effect on sleepiness.
The posts (see the 2005, 2006 and 2007 versions) tend to elicit a lot of comments.
I am not claiming that this hypothesis is correct, just that it co-exists with other hypotheses that are just as untested as this one. Read it under the fold:
Read the rest of this post… | Read the comments on this post…
“
(Via ScienceBlogs:Brain & Behavior.)
Posted by Mike on November 25, 2008 under 1. Info Collection |
Can pets catch colds from humans?: “
Can dogs catch a cold from a human?
We are looking after a 9-month-old Chihuahua who
ended up in a dog pound for 24 hours before her mom
rescued her back. She has started coughing and
sneezing for the last three days. The cough sounds like
something between a pig grunting and a goose honking.
Afraid it might be kennel cough or she caught a
cold from me.
Marley
Puyallup, WA
Although there are a few diseases (such as rabies, ringworm and intestinal worms) that can spread between pets and people, most of them don’t cause respiratory symptoms such as coughing or sneezing.
And, in particular, pets do not appear to be susceptible to human rhinoviruses (the germs that cause colds).
Most contagious diseases are species-specific. This means that, for the most part, dog germs spread only among dogs, cat germs spread only among cats, and human germs spread only among humans. It is very unlikely that the dog you’re looking after caught a cold from you.
However, a nine-month-old dog who recently got lost and spent a day in the pound is in the prime risk demographic for a number of canine respiratory diseases including kennel cough. The stress of being lost and ending up in the shelter no doubt weakened her immune system. Close confinement with large numbers of other dogs in the pound likely exposed her to a variety of canine pathogens. Dogs less than two years of age are especially susceptible to the sorts of germs that are common in shelters. And the symptoms you describe are very consistent with kennel cough.
In my opinion, the Chihuahua you’re looking after picked up her cough in the shelter. You are not to blame.
“
(Via Vet Blog: Information and Advice from Dr. Eric Barchas, DVM.)
Posted by Mike on November 22, 2008 under 1. Info Collection |
Man Says His Dog Detected His Skin Cancer: “A man from Banbury near Oxford, England, said his dog sniffed out his skin cancer, reminiscent of reports of trials that have shown dogs can detect cancer, in some cases even when screening tests can’t. Chris Tuffrey told the BBC yesterday that his pet Rottweiler, called Beamish, kept nuzzling and licking him and trying to get him to lift his arm.”
(Via Veterinary News From Medical News Today.)
Posted by Mike on November 20, 2008 under 1. Info Collection |
Metacognition in the Rat [The Frontal Cortex]: “
I’m a contributor to Very Short List: Science, the latest offshoot of the VSL brand. (David Dobbs is another contributor.) For those who don’t know, VSL is a very short email on something interesting sent daily to your inbox. We recently featured this paper in the Science channel:
We’ve always known that rats were capable of complex thought: They memorize mazes and form elaborate social hierarchies. Now we’re learning that they seem to think about thinking itself. Until recently, that crucial skill — called metacognition — was believed to be unique to humans.
Scientists at the University of Georgia tasked rats with identifying ’short’ and ‘long’ noises. Rodents that answered correctly were given six food pellets; those that answered wrong got nothing. So far, so Pavlovian. But the rats were also given a third option: If they declined to take the test, they received three food pellets. Most of the rats refused to identify the noises that were hardest to classify — thus suggesting a surprisingly evolved sense of their own knowledge and abilities. It’s something to think about the next time you reach for the rat poison.
For more on metacognition, check out my recent articles on the tip-of-the-tongue state and the presidential race.
Read the comments on this post…
“
(Via ScienceBlogs:Brain & Behavior.)
Posted by Mike on under 1. Info Collection |
Why do Dogs Get Ear Infections After Swimming?: “
My one-year-old Lab loves to swim. However, each
time he does, he gets an ear infection. How can we
prevent this?
Coleen
Philadelphia
Most Labrador Retrievers love to swim. Labradors, as a breed, are predisposed to ear infections. Swimming can trigger ear infections in some dogs.
Labradors and other floppy-eared breeds are prone to ear infections because the large external portions of their ears impede the circulation of air into the ear canal. This causes moisture to build up. Moisture promotes ear infections.
Dogs that swim also may develop excessive moisture in their ears through an obvious mechanism. This is why swimming triggers ear infections in some dogs.
Fortunately, solutions that remove moisture from the ear canals are available commercially. Over-the-counter formulations can be purchased at pet stores. More effective (in my experience) prescription ear solutions are available through vets.
Your vet can explain how to use ear drying solutions safely. If you use such a product after each of your dog’s swimming sessions, the ear infections might not occur.
“
(Via Vet Blog: Information and Advice from Dr. Eric Barchas, DVM.)
Posted by Mike on November 15, 2008 under 1. Info Collection |
Holiday Hazards: What Every Dog Owner Should Know: “
Yep, it’s that time again. The stores are filled with holiday decorations, we all wonder how the season could have snuck up on us so quickly…and dog trainers like me feel the need to warn everyone about the things that can harm dogs at the holidays.
Between planning family gatherings, decorating, gift-buying, and preparing way too much food, it’s easy to get overwhelmed and forget about the needs of our dogs. But the holidays are also the busiest time of the year for veterinary emergency clinics. Take a moment to read over these simple tips for keeping your dogs happy and safe during the holidays:
read more
“
(Via The Dog Blog.)
Posted by Mike on November 13, 2008 under 1. Info Collection |
Non-Chicken Laid First Chicken Egg [Aardvarchaeology]: “
What came first, the chicken or the egg? Easy, you say, eggs were laid by other animals aeons before the first chicken saw the light of day.
But what came first, the first chicken egg or the first chicken? This boils down to whether a chicken egg is one laid by a chicken or one out of which a chicken can hatch. Only the latter definition allows the question to remain open to discussion.
Biologically, a member of the chicken species could be defined by a list of alleles that must be present in its DNA if we’re to call it a chicken. And somewhere, sometime, the first bird that fulfilled that definition hatched. It hatched out of an egg laid by a non-chicken. As an adult, the first chicken (being lonely) probably mated with a bird that did not quite fulfil our definition of chickenhood, and so the first chicken probably laid non-chicken eggs. Out of these eggs hatched birds that almost, but not quite, fulfilled our definition of chickenhood. In subsequent generations, chicken eggs became more and more common. Later, after the geologically instantaneous speciation period, birds fulfilling the chicken species-definition became common and so chicken eggs were reliably produced generation after generation.
As they are still today: I boiled one Wednesday morning and served it to my daughter with soy sauce and a bowl of pao fan rice re-run gruel.
Read the comments on this post…
“
(Via ScienceBlogs: Life Science.)
Posted by Mike on under 1. Info Collection |
Parrots and Mirrors [The Frontal Cortex]: “
I’ve been really enjoying Alex and Me, the new book by Irene Pepperberg, and not only because I’ve got an African Grey of my own. It’s full of wonderful anecdotes like this:
The students occasionally took Alex to the washroom, where there was a very large mirror above the sinks. Alex used to march up and down the little shelf in front of the mirror, making noise, looking around, demanding things. Then one day in December 1980 when Kathy Davidson took him to the washroom, Alex seemed really to notice the mirror for the first time. He turned to look right into it, cocked his head back and forth a few times to get a fuller look, and said, ‘What’s that?’
‘That’s you,’ Kathy answered. ‘You’re a parrot.’
Alex looked some more and then said, ‘What color?’
Kathy said, ‘Gray. You’re a gray parrot, Alex.’ The two of them went through that sequence a couple more times. And that’s how Alex learned the color gray.
Obviously, we shouldn’t delude ourselves into thinking that we know what it’s like to be a parrot, anymore than we know what it’s like to be a bat, but still…There’s something tantalizingly familiar about the way in which Alex thinks, which is almost certainly a by-product of the complex social worlds of African Greys in the wild. As I’ve noted before, we can learn a lot about the evolution of intelligence by studying the avian cortex.
Read the comments on this post…
“
(Via ScienceBlogs:Brain & Behavior.)
