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Month: April 2013 (page 1 of 4)

04.30.2013

AIDS vaccine fails

Scanning electron micrograph of HIV-1 budding (in green) from cultured lymphocyte

The past two weeks brought plenty of interesting science news, including the failure of a potential AIDS vaccine. From Popular Science:

The study, called HVTN-505, was begun in 2009, over the years enrolling over 2,500 volunteers. The vaccination process doesn’t actually involve any live or even deactivated HIV; instead, it starts with one that includes genetic material that’s simply modeled after the virus, to prime the immune system. Then comes the real vaccine, involving recombinant DNA (meaning, DNA from various sources) based on adenovirus type 5, a common cold virus that in this case has been disabled so it doesn’t actually cause a cold. Attached to those adenoviruses are artificial versions of HIV antigens. Antigens–the term is short for antibody generator–trigger an immune response, and these artificial antigens were designed to attack the three major HIV subtypes.

This technique had shown some mild success before; in a study in Thailand in 2009, it showed a 31 percent reduction in the HIV infection rate, which sounds good to me, but is apparently not enough to really do more than encourage further research. Unfortunately, that was as much success as this strategy ever saw.

04.17.2013

creating oligodendrocytes

Oligodendrocyte

Popular Science covers two papers that appear in Nature Biotechnology on the topic of creating new brain cells. Researchers have developed a method to take skin cells from mice and rats and turn them into oligodendrocytes, which are the type of cells damaged by multiple sclerosis and other disorders.

From Popular Science:

The type of cell that the researchers made is a young, immature version of an oligodendrocyte. Oligodendrocytes normally wrap the nerve fibers of the brain and spinal cord in a protective coating called myelin. With certain diseases, though, people lose that coating or suffer damage to it, which can lead to severe symptoms, such as losing control of the arms and legs.

One major idea researchers have for curing such diseases is adding myelin back by transplanting young, immature oligodendrocytes into the patient. The cells are then supposed to mature and wrap themselves around exposed nerve fibers they find. (Older, more mature oligodendrocytes don’t seem as prone to finding and sheathing exposed nerve fibers.) The idea has worked in lab animals genetically engineered to not have myelin—wohoo!—but there’s a drawback. Until now, researchers generally made oligodendrocytes from stem cells taken from embryos. That’s fine for mice and rats, but it’s difficult to harvest and grow enough embryonic human stem cells for transplants in people.

04.15.2013

HIV testing by DVD

A recent paper in Lab on a Chip describes using a DVD player as a diagnostic tool. The researchers convert the optical drive into a laser scanning device that can count the number of CD4+ cells. From Phys Org:

Aman Russom, senior lecturer at the School of Biotechnology at KTH Royal Institute of Technology in Stockholm, says that his research team converted a commercial DVD drive into a laser scanning microscope that can analyse blood and perform cellular imaging with one-micrometre resolution. The breakthrough creates the possibility of an inexpensive and simple-to-use tool that could have far-reaching benefits in health care in the developing world.
“With an ordinary DVD player, we have created a cheap analytical tool for DNA, RNA, proteins and even entire cells,” says Russom. The so-called “Lab-on-DVD” technology makes it possible to complete an HIV test in just a few minutes, he says.
In a proof of concept demonstration, the researchers collected cell-type CD4 + from blood and visualized it using the DVD reader technology. Enumeration of these cells using flow cytometry is now standard in HIV testing, but the practice has been limited in developing countries.
HIV testing currently uses flow cytometry, which requires expensive equipment. If the DVD technique proves reliable, HIV testing can be done much more cheaply.
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