Tuesday, February 27, 2007

The Left Hand of Disease

Gene Expression reports on "a new study in Epidemiology on longevity and handedness in a large, representative sample of Dutch women (Ramadhani et al. 2007)."

Table 2 shows that, after adjustment for age, SES, BMI, and cigarette smoking status, left-handed women had a 1.36 times higher risk of dying from all causes than non-left-handed women. The adjusted HR for total mortality, after excluding the first 5 years of follow-up time, was 1.58 (95% CI = 1.03--2.42). With regard to cancer mortality, left-handed women had a 1.7 times greater risk of dying from any type of cancer (CI = 1.0--2.7), a 4.6 times higher risk of dying from colorectal cancer (1.5--14), and a 2.0-fold higher risk of dying from breast cancer (0.83--4.6). Handedness was weakly associated with overall mortality from diseases of the circulatory system (1.3, 0.54--3.3), although left-handed women had a 3.7 times greater risk of dying from cerebrovascular diseases than non-left-handed women.

See the link for more co-symptoms of left-handedness, and for the most likely explanation:

One thing seems pretty clear, though: common cases of deviance from Darwinian fitness are most likely caused by environmental insults, with pathogens being the most obvious culprit (see Cochran, Ewald, & Cochran 2000 for the rationale).

Monday, February 26, 2007

A Drug for Down Syndrome

United Press International reports on pentylenetetrazole (PTZ) as a treatment for Down Syndrome (trisomy 21):

Craig Garner, Fabian Fernandez and colleagues found that, after they gave mice genetically engineered to develop Down syndrome 17 daily doses of PTZ in milk, they performed as well as their wild-type counterparts when asked to identify novel objects and navigate a maze that simulated difficulties faced by human children and adults with Down syndrome.
The authors said that they thought this occurred because PTZ blocks the action of a neurotransmitter called GABA that is overproduced in people with Down syndrome and inhibits their ability to learn. When the amount of GABA in the brain was brought into balance with other neurotransmitters, normal learning was possible.

If you're wondering how they gave mice, who only have 20 pairs of chromosomes to start with, a trisomy for a chromosome they don't have, here's a BBC report from 2005 on doing just that.

Friday, February 16, 2007

The Smoking Peanut Butter

The AP reports on the salmonella outbreak traced to Peter Pan Peanut Butter and another ConAgra product:

Nearly 300 people in 39 states have fallen ill since August, and federal health investigators said they strongly suspect Peter Pan peanut butter and certain batches of Wal-Mart's Great Value house brand -- both manufactured by ConAgra Foods Inc.
Shoppers across the country were warned to throw out jars with a product code on the lid beginning with ''2111,'' which denotes the plant where it was made.
How the dangerous germ got into the peanut butter was a mystery. But because peanuts are usually heated to high, germ-killing temperatures during the manufacturing process, government and industry officials said the contamination may have been caused by dirty jars or equipment.

This outbreak of a rare salmonella strain has been going on since August:

The strain in this outbreak, Salmonella serotype Tennessee, is comparatively rare, as is salmonella contamination of peanut products, said Caroline Smith DeWaal, director of food safety at the Center for Science in the Public Interest.
It may have taken a long time to identify peanut butter as the source because ''it's just not one of the first things you'd suspect,'' Smith DeWaal said.

Tuesday, February 13, 2007

Where have all the gametes gone?

Strangely enough, an unnamed source was just telling me last night about theories of vasectomy-induced autoimmune reactions to all those trapped sperm. Today Reuters reports on research linking vasectomies to two forms of dementia:

Researchers at Northwestern University in Illinois, writing in the journal Cognitive and Behavioral Neurology, linked this male sterilization surgery to a neurological condition called primary progressive aphasia, or PPA.
They surveyed 47 men with the condition being treated at Northwestern's Cognitive Neurology and Alzheimer's Disease Center, as well as 57 men who did not have PPA. Their ages ranged from 55 to 80.
Of those with primary progressive aphasia, 40 percent had undergone a vasectomy, compared with 16 percent of the others. Those with PPA also suffered the ailment an average of four years earlier than the others.
Preliminary data also linked vasectomies to another form of dementia involving behavioral changes. Among 30 men with frontotemporal dementia, more than a third had undergone a vasectomy, the researchers said.

The lead researcher postulates an autoimmune response:

The study did not look at the mechanism behind any link between PPA and vasectomies, but Weintraub said it may be because the surgery allows sperm to leak into the blood. Antibodies produced by the immune system in response to the sperm might trigger damage that causes dementia, she said.

Monday, February 12, 2007

The New Hysteria

Via GeekPress: Nature reports on research into the origins of the psychological notion of repressed memory:

To see how long the idea of repressed memories have been around, a group of psychologists and literature scholars turned to historical writings.
They could not find a single description of repressed memory, also referred to as dissociative amnesia, in fiction or factual writing before 1800.

Apparently it was all just a Freudian slip...

Sunday, February 04, 2007

DCA Research Page

The University of Alberta now has a webpage of DCA Reseach Information, including plans for clinical trials:

Investigators at the University of Alberta have recently reported that a drug previously used in humans for the treatment of rare disorders of metabolism is also able to cause tumor regression in a number of human cancers growing in animals. This drug, dichloroacetate (DCA), appears to suppress the growth of cancer cells without affecting normal cells, suggesting that it might not have the dramatic side effects of standard chemotherapies.
At this point, the University of Alberta, the Alberta Cancer Board and Capital Health do not condone or advise the use of dichloroacetate (DCA) in human beings for the treatment of cancer since no human beings have gone through clinical trials using DCA to treat cancer. However, the University of Alberta and the Alberta Cancer Board are committed to performing clinical trials in the immediate future in consultation with regulatory agencies such as Health Canada.

Saturday, February 03, 2007

Bagged and Tagged

PlagueBlog was recently upgraded to the new Google Blogger, which made it possible to label all previous posts by disease. Not surprisingly, flu came out first, while Marburg, the eponymous plague, and the transmissible spongiform encephalopathies (TSE) all made a respectable showing.

On the lighter side, there are some non-disease-specific categories: PlagueFun, don't try this at home (formerly known as the Don't Kiss the Chickens department), paging Dr. Frankenstein (a.k.a., don't resurrect the Spanish Flu in your BSL 3 lab just because you can), and PlagueBlog recommends (...cooking the blood of your H5N1-infected poultry before drinking it to protest your government's half-hearted attempts to stamp out bird flu, for example).

Friday, February 02, 2007

Bird Flu Kills At Least One Nigerian

Reuters reports on the first human death from bird flu in Nigeria:

The 22-year-old died after feathering and disembowelling an infected chicken. She was from Lagos, the commercial capital of Africa's most populous country, Information Minister Frank Nweke said.
Test [sic] on three other victims, one of them the woman's mother, were inconclusive.
Nigeria was the first African nation to detect the H5N1 virus in poultry last year and had conducted tests on 14 people suspected of having the virus.

The WHO is taking it in stride:

World Health Organisation spokesman Gregory Hartl said a human case of bird flu in Nigeria was to be expected because of the experience in other countries, such as Indonesia, with huge poultry populations where chickens and hens live in close proximity to humans.
"It does not change anything from a public health point of view," Hartl said. "It had to happen sooner or later."