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Recent TED Talk by Marc Kosca on the health concerns associated with syringe re-use and his non-profit SafePoint (posted October 2009). The comments in response to Kosca’s talk are particularly interesting.

For people not familiar with TED talks, they are a series of talks posted on the internet about a range of topics. They are freely available to everyone with internet access, and are supported by TED, a non-profit organization focused on open access information.

From the site:

TED is a small nonprofit devoted to Ideas Worth Spreading. It started out (in 1984) as a conference bringing together people from three worlds: Technology, Entertainment, Design. Since then its scope has become ever broader. Along with the annual TED Conference in Long Beach, California, and the TEDGlobal conference in Oxford UK, TED includes the award-winning TEDTalks video site, the Open Translation Program, the new TEDx community program, this year’s TEDIndia Conference and the annual TED Prize.

There are a number of TED talks on health, poverty, as well as a number of other topics. Definitely worth checking out.

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This article was posted on the University of Florida website Monday, November 23rd. It appears that 20 cases of Dengue were identified in Key West, FL. The outbreak is not expected to go beyond Monroe County, however, it has raised concerns among researchers about the possible reemergence of dengue virus.

Besides the dengue re-emergence in the Florida Keys, Connelly, based at the Florida Medical Entomology Laboratory in Vero Beach, said health officials were surprised by a door-to-door survey of Key West residents. Connelly and Jonathan Day, a medical entomology professor at the Vero Beach laboratory, collaborate with the health and vector-control officials.

After some 240 residents allowed health officials to draw a small blood sample, test results showed that 41 percent had been exposed to the dengue virus or other Flavivirus, either through exposure to one of the viruses or through vaccinations, such as the yellow fever vaccine.

“Much like a lot of other mosquito-borne diseases, some people can have it and not have any symptoms, while others end up very sick,” Connelly said.

Interesting article from the New York Times on another way that exercise may help create resiliency to stress. Research presented at the annual meeting for the Society for Neuroscience showed that there appeared to be a difference in the way that active and non-active rats processed stress. Certain cells were developed among the active “running” rats which responded differently when the animals were exposed to cold stress.

The “cells born from running,” the researchers concluded, appeared to have been “specifically buffered from exposure to a stressful experience.” The rats had created, through running, a brain that seemed biochemically, molecularly, calm.

This is an interesting development. We’ve known for awhile that exercise seems to have a positive effect on affect and the brain. I think it would be interesting to look at whether there is a range of exercise (type, intensity, duration), that affects the ways these cells operate. For example, are some exercises better than others? Or is endurance exercise as beneficial as short running activities?

What do you think? In the meantime I’m going to get on the treadmill…

This Radiolab discussion from September 25, 2009 is one of the most interesting I’ve heard about parasites recently. It includes a discussion of the history of hookworm eradication in the U.S., toxoplasma gondii controlling rat brains, zombie cockroaches, and Aliens (the movie). Do I have your attention? Take a listen for yourself…

Sense of scale

Here is an interesting visualization from the University of Utah that shows the relative size of various pathogens and microbes. Interesting when you consider the havoc that these tiny organisms have caused among humans for thousands of years.

Humans are not the only animals to undergo reproductive cessation. There are several species that go through menopause including non-human primates, whales, rodents, dogs, rabbits, elephants and domestic livestock. We are unique in that we undergo menopause at a relatively early age compared with other species. A long post-reproductive lifespan presents an evolutionary puzzle, however, because theory suggests that there should be no selection for genes which promote survival past the end of reproduction. So, why do humans go through menopause so early?

One argument, called the “Grandmother Hypothesis” suggests that the presence of menopause at such a young age has to do with the benefit of extended familial groups in which the continued presence of the older female contributes to the survival of young even though they themselves can no longer reproduce. (See Hawkes et al. 1998 or this article in the New York Times for a basic discussion of the theory).

In hunter-gatherer cultures today, said Dr. Hawkes, “women are strong and economically productive into their 60s….Women are not being helped along by others. The flow of help is going into the other direction.”

Research on the Grandmother Hypothesis was bolstered by a 2004 study published in Nature by Lahdenpera et al. which identified that children are 12% more likely to survive to adulthood when they have a grandmother’s support than when they don’t. Recently, Cant and Johnstone (2007) extended the life of the “Grandmother Hypothesis” by proposing that the timing of reproductive cessation in humans is best understood as an evolutionary adaptation to reduce reproductive competition between generations of females in the same family unit. Shanley et al. (2007) suggest that it is necessary to meet multiple conditions in order to significantly enhance fitness.

For menopause to be adaptive there must be a combination of factors, and we have shown that the most important are a dramatic increase in maternal mortality with age and a benefit to grandchildren provided by the maternal grandmother. (p. 2949).

However, earlier menopause has also been observed among animals in which females provide very little or no reproductive care, such as this case in female guppies, leading many to debate whether this hypothesis is accurate  for understanding the early cessation of reproduction among humans. In 1998, Packer et al. argued against the Grandmother Hypothesis using data from Tanzanian lions and baboons. More recently, Holmes (2008) argues that midlife fertility loss is not unique to humans, but represents a canonical reproductive aging pattern shared by other female vertebrates when a high proportion of healthy, aged individuals are released from selection for continued reproduction. Others like Marlowe (2000) have argued that maybe it’s not about mothers at all, and that once males became capable of maintaining high status and reproductive access beyond their peak physical condition, selection favored the extension of maximum life span in males and early menopause on females is a byproduct of the loss of oocytes combined with increased lifespan.

The debate is complicated by the fact that researchers aren’t always arguing over the same issue. Some researchers are trying to understand why menopause is only present among certain species, while others like Hawkes et al., Shanley et al., Marlowe, and Holmes are trying to understand why menopause occurs at such a young age among humans. Clearly more work is necessary…

Article from the Miami Herald about the interaction between Tylenol and vaccination in children.

It is the first major study to tie reduced immunity to the use of fever-lowering medicines. Although the effect was small and the vast majority of kids still got enough protection from vaccines, the results make “a compelling case” against routinely giving Tylenol right after vaccination, say doctors from the U.S. Centers for Disease Control and Prevention.

You can read the whole Miami Herald article here. The original research article published in the Lancet is here.