brdgt | Science Tuesday - Autism, Corn, Mating Habits, and Dengue Fever

British Medical Council Bars Doctor Who Linked Vaccine With Autism
By JOHN F. BURNS, The New York Times, May 24, 2010

LONDON — A doctor whose research and public statements caused widespread alarm that a common childhood vaccine could cause autism was banned on Monday from practicing medicine in his native Britain for ethical lapses, including conducting invasive medical procedures on children that they did not need.

The General Medical Council applied its most severe sanction against the doctor, Andrew Wakefield, 53, who abandoned his medical practice in Britain in 2004 as questions intensified about his research and set up a center to study childhood developmental disorders in Texas, despite not being licensed as a physician there.

In January, after the longest investigation in its history, the council found several instances of what it said was unprofessional conduct by Dr. Wakefield. It cited his taking blood samples for his study from children at his son’s birthday party; he paid each child £5, about $7.20 today, and joked about it later. It also noted that part of the costs of Dr. Wakefield’s research was paid by lawyers for parents seeking to sue vaccine makers for damages.

Dr. Wakefield left the Texas center in February, but continued to speak out against his treatment in Britain, as he did in interviews in New York on Monday, when he called the British decision to strike him off the medical register an effort to “discredit and silence” him. He said he would appeal the decision, which will take effect, unless suspended for legal reasons, within 28 days.

The disciplinary tribunal’s action came after more than a decade of controversy over the links Dr. Wakefield and associates in Britain, as well as supporters among parents of some autistic children in Britain and the United States, have made between autism and a commonly used vaccine for measles, mumps and rubella. The suggestion of a link caused use of the vaccine in Britain and elsewhere in the world to plummet, a development that critics of Dr. Wakefield said contributed to a sharp rise in measles cases in countries where the vaccine was in use.

Most scientific papers have failed to find any links between vaccines and autism.

The furor was touched off by a 1998 article in The Lancet, a British medical journal. The journal retracted the study in February after the medical council in London concluded in January that Dr. Wakefield had been dishonest and that he had violated ethical rules.

The council said he had shown “a callous disregard” for the suffering of children involved in his research. The ruling banning him from practicing medicine on Tuesday was a sequel to the January finding.

Dr. Surendra Kumar, the medical council’s chairman, said that Dr. Wakefield had “brought the medical profession into disrepute” and that his behavior constituted “multiple separate instances of professional misconduct.” In all, Dr. Wakefield was found guilty of more than 30 charges.

“The panel concluded,” Dr. Kumar said, “that it is the only sanction that is appropriate to protect patients and is in the wider public interest, including the maintenance of public trust and confidence in the profession.” He said the sanction was “proportionate to the serious and wide-ranging findings made against him.”

The council also barred from practice one of Dr. Wakefield’s associates, Dr. John Walker-Smith, 73, who had been found guilty of professional misconduct and retired from medicine 10 years ago. A second associate, Dr. Simon Murch, was found not guilty of professional misconduct and allowed to continue practicing.

Dr. Wakefield resigned in February from his position as a staff researcher at Thoughtful House, an alternative medicine clinic in Austin, Tex. A spokeswoman for the clinic said she did not know where Dr. Wakefield worked now.

A 2007 annual report for the clinic has a picture of Dr. Wakefield looking into microscope with a caption that reads: “Where would we be without Dr. Wakefield and your entire team? Thank you for your courageous efforts in swimming against the tide. Without you we would still be hearing, ‘There is nothing we can do.’ Because of you we know the hope is great and the progress is attainable.”

In New York on Monday, Dr. Wakefield rejected the medical council’s findings. In an interview with the “Today” show on NBC, he described the ban on his practicing as “a little bump in the road” and said the council’s decision had been predetermined “from the outset.” He also said he would continue his research into the link between vaccines and autism.

“These parents are not going away,” he said. “The children are not going away. And I am most certainly not going away.”

Gardiner Harris contributed reporting from Washington.

Tracking the Ancestry of Corn Back 9,000 Years
By SEAN B. CARROLL, The New York Times, May 24, 2010

It is now growing season across the Corn Belt of the United States. Seeds that have just been sown will, with the right mixture of sunshine and rain, be knee-high plants by the Fourth of July and tall stalks with ears ripe for picking by late August.

Corn is much more than great summer picnic food, however. Civilization owes much to this plant, and to the early people who first cultivated it.

For most of human history, our ancestors relied entirely on hunting animals and gathering seeds, fruits, nuts, tubers and other plant parts from the wild for food. It was only about 10,000 years ago that humans in many parts of the world began raising livestock and growing food through deliberate planting. These advances provided more reliable sources of food and allowed for larger, more permanent settlements. Native Americans alone domesticated nine of the most important food crops in the world, including corn, more properly called maize (Zea mays), which now provides about 21 percent of human nutrition across the globe.

But despite its abundance and importance, the biological origin of maize has been a long-running mystery. The bright yellow, mouth-watering treat we know so well does not grow in the wild anywhere on the planet, so its ancestry was not at all obvious. Recently, however, the combined detective work of botanists, geneticists and archeologists has been able to identify the wild ancestor of maize, to pinpoint where the plant originated, and to determine when early people were cultivating it and using it in their diets.

The greatest surprise, and the source of much past controversy in corn archeology, was the identification of the ancestor of maize. Many botanists did not see any connection between maize and other living plants. Some concluded that the crop plant arose through the domestication by early agriculturalists of a wild maize that was now extinct, or at least undiscovered.

However, a few scientists working during the first part of the 20th century uncovered evidence that they believed linked maize to what, at first glance, would seem to be a very unlikely parent, a Mexican grass called teosinte. Looking at the skinny ears of teosinte, with just a dozen kernels wrapped inside a stone-hard casing, it is hard to see how they could be the forerunners of corn cobs with their many rows of juicy, naked kernels. Indeed, teosinte was at first classified as a closer relative of rice than of maize.

But George W. Beadle, while a graduate student at Cornell University in the early 1930s, found that maize and teosinte had very similar chromosomes. Moreover, he made fertile hybrids between maize and teosinte that looked like intermediates between the two plants. He even reported that he could get teosinte kernels to pop. Dr. Beadle concluded that the two plants were members of the same species, with maize being the domesticated form of teosinte. Dr. Beadle went on to make other, more fundamental discoveries in genetics for which he shared the Nobel Prize in 1958. He later became chancellor and president of the University of Chicago.

Despite Dr. Beadle’s illustrious reputation, his theory still remained in doubt three decades after he proposed it. The differences between the two plants appeared to many scientists to be too great to have evolved in just a few thousand years of domestication. So, after he formally retired, Dr. Beadle returned to the issue and sought ways to gather more evidence. As a great geneticist, he knew that one way to examine the parentage of two individuals was to cross them and then to cross their offspring and see how often the parental forms appeared. He crossed maize and teosinte, then crossed the hybrids, and grew 50,000 plants. He obtained plants that resembled teosinte and maize at a frequency that indicated that just four or five genes controlled the major differences between the two plants.

Dr. Beadle’s results showed that maize and teosinte were without any doubt remarkably and closely related. But to pinpoint the geographic origins of maize, more definitive forensic techniques were needed. This was DNA typing, exactly the same technology used by the courts to determine paternity.

In order to trace maize’s paternity, botanists led by my colleague John Doebley of the University of Wisconsin rounded up more than 60 samples of teosinte from across its entire geographic range in the Western Hemisphere and compared their DNA profile with all varieties of maize. They discovered that all maize was genetically most similar to a teosinte type from the tropical Central Balsas River Valley of southern Mexico, suggesting that this region was the “cradle” of maize evolution. Furthermore, by calculating the genetic distance between modern maize and Balsas teosinte, they estimated that domestication occurred about 9,000 years ago.

These genetic discoveries inspired recent archeological excavations of the Balsas region that sought evidence of maize use and to better understand the lifestyles of the people who were planting and harvesting it. Researchers led by Anthony Ranere of Temple University and Dolores Piperno of the Smithsonian National Museum of Natural History excavated caves and rock shelters in the region, searching for tools used by their inhabitants, maize starch grains and other microscopic evidence of maize.

In the Xihuatoxtla shelter, they discovered an array of stone milling tools with maize residue on them. The oldest tools were found in a layer of deposits that were 8,700 years old. This is the earliest physical evidence of maize use obtained to date, and it coincides very nicely with the time frame of maize domestication estimated from DNA analysis.

The most impressive aspect of the maize story is what it tells us about the capabilities of agriculturalists 9,000 years ago. These people were living in small groups and shifting their settlements seasonally. Yet they were able to transform a grass with many inconvenient, unwanted features into a high-yielding, easily harvested food crop. The domestication process must have occurred in many stages over a considerable length of time as many different, independent characteristics of the plant were modified.

The most crucial step was freeing the teosinte kernels from their stony cases. Another step was developing plants where the kernels remained intact on the cobs, unlike the teosinte ears, which shatter into individual kernels. Early cultivators had to notice among their stands of plants variants in which the nutritious kernels were at least partially exposed, or whose ears held together better, or that had more rows of kernels, and they had to selectively breed them. It is estimated that the initial domestication process that produced the basic maize form required at least several hundred to perhaps a few thousand years.

Every August, I thank these pioneer geneticists for their skill and patience.

Male Antelopes Scare Partners Into Sex
By SINDYA N. BHANOO, The New York Times, May 24, 2010

This is a story about deception and sex in the wild plains of Kenya.

Antelope deception, that is, for the purposes of sex.

During mating season, a male topi antelope will try to keep females in heat from leaving his territory by pretending that a predator might be in the area, according to a study that will appear in the July issue of The American Naturalist.

When a female appears to be leaving, the male will run in front of her, freeze in place, stare in the direction that she is going and snort loudly. Typically, that snort means that a predatory lion or cheetah was spotted, but in this case the male is faking it.

“He doesn’t look at the female. He takes a rigid stance exactly as if there were a predator there,” said Jakob Bro-Jorgensen, a research fellow at the University of Liverpool who led the study. Dr. Bro-Jorgensen, who studied the behavior of hundreds of topi antelopes in the Masai Mara National Reserve, said the males acted this way time after time.

Although scientists have observed males deceiving other males to gain access to mates, this is the first finding of a male duping his own sexual partner, Dr. Bro-Jorgensen said. Hearing the snort, the female antelope generally retreats back into the male’s territory, where he will attempt to mate with her right away. Females mate with many males each season, and it would seem that they might catch on after a while. But getting fooled does not have much of a downside, while ignoring what might be a real warning could be deadly.

“It’s too dangerous to take the chance,” Dr. Bro-Jorgensen said.

Asked whether this sort of behavior might occur in humans, Dr. Bro-Jorgensen said he did not know, but “We are masters of deception, so of course you can speculate.”

Tropical Diseases: Outbreak of Dengue Fever Is Reported in Florida, Health Officials Say
By DONALD G. McNEIL Jr., The New York Times, May 24, 2010

Dengue fever, a growing scourge in the tropics, has established itself in a popular American tourist destination, federal health officials reported last week.

Last August, an alert doctor in upstate New York realized that one of his patients, whose only recent travel had been to Key West, Fla., had dengue — a mosquito-borne virus that causes joint pain so severe it is nicknamed “break-bone fever” in Latin America and Asia. According to last week’s report from the Centers for Disease Control and Prevention, Florida health authorities have since found 27 more cases, all in Key West, the last in April. Most victims had a fever and pain in the head, body and eyes, and some had a rash.

The C.D.C. advised doctors to consider a dengue diagnosis in patients with similar symptoms who have been to subtropical parts of the United States. Although there have been outbreaks along the Texas-Mexico border since 1980, the disease had not been seen in Florida since 1934.

Unlike malaria, which is caused by a parasite, dengue is a virus, and there is no cure. Patients usually recover on their own. But in rare cases it can turn into dengue hemorrhagic fever or dengue shock syndrome, which can be fatal. Dengue cases have increased in the past 20 years in travelers returning from the Caribbean, South America and Asia, and people with the virus in their blood may transmit it to local mosquitoes. Now Florida has increased its mosquito-control measures.