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Flash
158154.  Wed Mar 21, 2007 4:56 am Reply with quote

Not sure whether this works, in two ways: 1) it's based on research which was done a couple of years ago, and perhaps it has since been repudiated for all I know and 2) I need to check whether enough people know the "wrong" answer.

On the latter point, I tested it at a dinner last night and everybody there did immediately state the "wrong" answer and refused to believe that it was wrong, so on that basis it would seem to qualify as Gen Ig, but could you let me know whether it's something you've all heard of?

Another problem is that I can't think of a good way to phrase the question - help on that, too, please. If push comes to shove, and if the reearch doesn't collapse on closer examination, then it's definitely at least a good note for SF when he's talking about eggs (ie not necessarily a question in its own right).

Sorry, huge long preamble. See next post for the substance.

 
Flash
158157.  Wed Mar 21, 2007 5:07 am Reply with quote

At school I was taught that girls are born already containing all the ova they will ever produce, that they release these through the course of their lives, and when they're gone, they're all gone.

Apparently this has been the dogma in medical circles since 1951, and no-one has ever thought to test it - but it's wrong:

Quote:
When Massachusetts General Hospital's Dr. Jonathan Tilly was rooting around in fertility research during the 1990s, he kept running into "the dogma." It was something he'd learned in medical school, something he took for granted.

The dogma, as fertility scientists still call it, was that a woman's egg supplies decrease with age until none of the hundreds of thousands of eggs she had at birth are left. That's why women face difficulties conceiving from their mid-30s on. Several important papers over the years asserted this, and medical textbooks to this day state it as fact.

"When I got my PhD, that's what I was taught," says Tilly, a boyish-looking researcher who works out of Mass. General's new labs in the Charlestown Navy Yard. "The dogma was so strong, no one thought to challenge it."

Tilly was an expert in how cells die. A few years ago, he wanted to study the way egg cells die as females age. So he began to map out the process -- and was stunned at what he found.

Eggs in the test mice were dying at an unexpectedly rapid clip. At that speed, they should run out much earlier in life. But they don't. The implication was clear: Somehow, while some eggs were dying off, new eggs were simultaneously being manufactured -- a direct contradiction of the dogma.

"We were floored," Tilly says. "Even when I think about it now, I get goose bumps."

Tilly and his small team of researchers decided to keep the finding to themselves, until they could muster more proof. But Tilly immediately saw the implications: Methods could be devised to stimulate egg production for women later in life. ...

His lab performed a battery of creative experiments. It appears that females have stem cells, the plastic-like cells that give rise to all bodily organs, in their reproductive tract that produce new eggs well into life.

Last March (2004) Tilly's research was released, generating worldwide headlines. The dogma began crumbling.


http://www.boston.com/news/politics/conventions/articles/2004/07/26/defying_dogma/
http://www.sciam.com/article.cfm?chanID=sa003&articleID=00063AD0-9DDB-104F-9DDB83414B7F0000

 
eggshaped
158158.  Wed Mar 21, 2007 5:15 am Reply with quote

I thought that, or rather I was told it at school and never thought to question it.

 
MatC
158167.  Wed Mar 21, 2007 5:53 am Reply with quote

You see Egg, Flash - that was your mistake. I , too, was taught wrong things at school. But I never listened to a word they told me, so although I have ended up not knowing a lot of right things, I balance that out by also not knowing a lot of wrong stuff.

(I do know, however, that eggs come from chickens, not girls. We did that in Form One, before I fell asleep for 13 years.)

 
MatC
158175.  Wed Mar 21, 2007 6:04 am Reply with quote

Speaking of things we’re not, after all, born with a finite supply of, have we done brain cells? If not ...

<<<MYTHCONCEPTIONS: Brain cells by Mat Coward

THE MYTH: You can’t grow more brain cells. Every human starts with a finite number, some of which are destroyed - and never replaced - every time we figure out what two plus two makes, or try to remember where we’ve left our glasses.

THE "TRUTH": This-still prevalent belief was expelled from the halls of orthodoxy some years ago, when scientists discovered that all vertebrate animals continue to produce new neurons (brain cells) throughout their lives, in at least some parts of the brain. More recently, it has been shown that the fresh cells are actively involved in the formation of memory. Other studies strongly suggest that some types of anti-depressants work by causing new neuron growth - and that depression itself can inhibit brain cell replacement. Readers will be unsurprised to learn that evidence for adult neuron growth was first presented in the 1960s, and again in the 1980s, but was dismissed out of hand for no reason other than that it contradicted existing (untestable) theories.

SOURCES: www.livescience.com/humanbiology/051227_neuron_growth.html; www.mult-sclerosis.org/news/Mar2001/TheBrainMakesNewNeurons.html; http://mentalhealth.about.com/cs/psychopharmacology/a/neurogenesis.htm; www.newscientist.com/channel/being-human/mg18625011.900; www.newscientist.com/channel/being-human/brain/mg16522254.200; _The New York Times_, 30 Oct 1998.

DISCLAIMER: Most of the evidence so far seems to pertain to that shamefully persecuted species, the laboratory rat; historically-minded Forteans might remember that it was pioneering vivisection work which proved beyond doubt that heroin was utterly non-addictive. >>>

 
dr.bob
158178.  Wed Mar 21, 2007 6:07 am Reply with quote

I seem to recall reading somewhere that, if given in carefully controlled laboratory conditions, heroin really is non-addictive. The addiction only comes about if you overdose slightly (i.e. take more than the recommended dose).

Though I don't have any references to hand, so that might be complete rubbish.

 
Jenny
158249.  Wed Mar 21, 2007 8:30 am Reply with quote

That egg thing (and the brain cell thing) was totally new to me Flash, so I think it might make a good Gen Ig point. It does make sense that in an otherwise dynamic system the ovaries wouldn't be the only bit that acted like a tank full of petrol that runs out slowly as it's used.

Bob - my first husband was a research chemist and the way he explained the heroin addiction thing to me (in simple terms that a non-scientist like me could more or less grasp so it may not be entirely accurate) was that if there was more input into the system than the existing opioid receptors could process, more receptors would be created. If the input then ceased, you would be left with more opioid receptors than you needed, and they would respond to the withdrawal of the stimulus for a while, giving withdrawal symptoms, until they closed down (not sure that's accurate). That's why people who are given opioids for actual pain don't tend to become addicted to them if the opioids are withdrawn as the pain diminishes. That is more or less what you are saying, I think.

 
MatC
158381.  Wed Mar 21, 2007 12:06 pm Reply with quote

The version of that I heard years ago, Bob, was that proper laboratory Heroin wasn’t addictive - that it was only street heroin which was. Certainly it used to be a “well known fact” amongst knowers of well known facts that heroin was non-addictive (also that, unlike cocaine, it is entirely harmless in and of itself). Like you, I’ve no sources for that, and no reason to believe or disbelieve it.

Of course, it’s certainly true that plenty of people use heroin recreationally for years without ever becoming addicted - but then that’s true of all “addictive” substances. I know of two major studies which have been done on non-addicted long-term heroin users.

 
dr.bob
158586.  Thu Mar 22, 2007 5:41 am Reply with quote

MatC wrote:
The version of that I heard years ago, Bob, was that proper laboratory Heroin wasn’t addictive - that it was only street heroin which was.


That ties in nicely with the point I made. Where-ever I read it, it went on to point out that it's impossible to know precisely how much heroin you're taking if you're using street heroin since it tends to be cut with all sorts of random stuff. For that reason, and also given addicts' tendency to take a bit more to make sure they get a decent rush, it's much more likely that you'll take a slight overdose, and therefore get addicted, if you're using street heroin.

 
MatC
158591.  Thu Mar 22, 2007 5:48 am Reply with quote

Hmmm ... I wonder if this is worth pursuing? I mean, “Is heroin addictive?” would make a bloody good klaxon question!

 
Gray
158594.  Thu Mar 22, 2007 5:55 am Reply with quote

I think this is largely dependent on what we mean by 'addicted' here - it's a very vague term.

I mean, how does one tell if a person who's been using heroin all his life isn't actually addicted?

Any chemical that causes pleasure, and which can take the place of the brain's natural pleasure drugs, is 'addictive'.

Wiki says:
Quote:
The medical community now makes a careful theoretical distinction between physical dependence (characterized by symptoms of withdrawal) and psychological dependence (or simply addiction). Addiction is now narrowly defined as "uncontrolled, compulsive use"; if there is no harm being suffered by, or damage done to, the patient or another party, then clinically it may be considered compulsive, but to the definition of some it is not categorized as "addiction". In practice, the two kinds of addiction are not always easy to distinguish. Addictions often have both physical and psychological components.


, which is quite sensible. And also

Quote:
In modern pain management with opioids physical dependence is nearly universal but addiction is rare.

Not all doctors agree on what addiction or dependency is, because traditionally, addiction has been defined as being possible only to a psychoactive substance...


http://en.wikipedia.org/wiki/Addiction

 
Flash
158609.  Thu Mar 22, 2007 6:03 am Reply with quote

Iconoclasm is all very well, but we aren't going to use a comedy panel game to tell people in 15 seconds that Stephen Fry says it's OK to take heroin. We just aren't.

 
dr.bob
158614.  Thu Mar 22, 2007 6:10 am Reply with quote

Spoilsport!

 
eggshaped
174790.  Wed May 16, 2007 3:07 am Reply with quote

Apparently the medical dogma that a woman is born with all her eggs is back in favour. OK, so mice might create new eggs, but humans don't according to a study which ovary genes and fetus genes. In conclusion:

Quote:
From the 1850s until 1951, scientists assumed women made new eggs during sexual maturation. But research published in 1951 by biologist Solly Zuckerman changed people's thinking when he showed that a female is born with all of her eggs.

"Because of the new techniques available to us, it is always good for science to reexamine theories," Bahr said. "But then when we do examine them, we really need to present rigorous data to confirm that a long held theory isn't true. With our new tools, we can ask: Will this theory established in 1950 still stand today?" she said. "The Liu paper has confirmed Zuckerman's research."


link

 
Flash
174806.  Wed May 16, 2007 3:51 am Reply with quote

The fox shoots back:
Quote:
In reaction to Liu's results, Tilly wrote a response in a different journal, Cell Cycle, stating in its April issue, "It is disappointing to see arguments against the possibility of postnatal oogenesis in mammals still being drawn using solely an 'absence of evidence' approach."

but basically, he's as good as stuffed and mounted. Dang.

 

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