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Thursday, 12 February 2009

Microstuff - the war is not over

Today:

  1. Dressed to Kill: From Virus to Vaccine
  2. Turning down gene expression promotes nerve cell maintenance
  3. Targeted nanospheres find, penetrate, then fuel burning of melanoma
Eyes on the first and the last article. Pretty cool!

Dressed to Kill: From Virus to Vaccine

(PhysOrg.com) -- In a pioneering effort, researchers at the National Institute of Standards and Technology and the University of Queensland in Australia have successfully demonstrated that they can count, size and gauge the quality of virus-like particle-based (VLP) vaccines much more quickly and accurately than previously possible. Their findings could reduce the time it takes to produce a vaccine from months to weeks, allowing a much more agile and effective response to potential outbreaks.

Viruses are small, simple bodies consisting of DNA or RNA wrapped in a protein shell studded with short strands of protein. Viruses use these short strands of protein like a skeleton key to unlock and invade healthy cells, replace their DNA, hijack the cells’ replication machinery and turn them into virus-producing factories. As with smallpox and influenza, the only way to combat the virus is through vaccination, in which dead or weakened viruses are injected into the body. Unable to cause any real harm, the dead or weakened viruses allow the body to develop antigens that can fight off the infection in the future.

“The problem with this approach is that it takes a long time to develop vaccines” said Leonard Pease, a NIST researcher working on the project.

In order to speed the creation and delivery of these life-saving treatments, scientists at NIST and the University of Queensland in Australia are working to develop a new class of vaccines with virus-like particles (VLP). First used in the cervical cancer vaccine, VLP-based vaccines consist of an artificial protein shell that has been coated with proteins specific to whatever disease the vaccine is intended to control. Although the VLP is dressed up to look like the real thing to the body’s immune system, it contains no DNA or RNA and is incapable of causing infection. Because VLPs do not have to be grown, vaccines based on these particles can be deployed much faster than traditional vaccines.

Whether or not a VLP-based vaccine will be effective depends on whether the VLPs are well-formed and properly coated. NIST researcher Leonard Pease and his team were able to determine that well-formed VLPs that have been coated with bird flu proteins are 2 nanometers larger than those without, a critical step towards the creation of future bird flu vaccines. source

My comment:That sounds really cool. Ok, I'm not too keen on vaccines, but if they are safe they are fine by me. And even if they are not so safe, sometimes they are badly needed! And this technique looks quite promising. Good luck guys!

Turning down gene expression promotes nerve cell maintenance

Normal nerve cells have a myelin sheath, which, much like the insulation on a cable, allows for rapid and efficient signal conduction. However, in several diseases - the most well-known being multiple sclerosis - demyelination processes cause the breakdown of this "insulation", and lead to deficits in perception, movement, cognition, etc. Thus, in order to help patients of demyelinating disease, researchers are studying the pathways that control myelin formation and maintenance.

A new study by University of California scientists examines the role of a structural protein, called lamin, in maintaining myelin. They found that, while lamin is necessary in the initial stages of myelin formation, too much lamin promotes myelin breakdown. Further investigation led the researchers to the discovery of a signal that fine-tunes lamin expression. This signal, a microRNA called miR-23, can turn down lamin gene expression, and thereby prevent demyelination due to lamin overexpression.source

My comment: Not too much to comment except that this is a great news. Does anyone but me wonder why after all those discoveries we never see drugs? Bad luck or conspiracy?


Targeted nanospheres find, penetrate, then fuel burning of melanoma

February 2nd, 2009

Hollow gold nanospheres equipped with a targeting peptide find melanoma cells, penetrate them deeply, and then cook the tumor when bathed with near-infrared light, a research team led by scientists at The University of Texas M. D. Anderson Cancer Center reported in the Feb. 1 issue of Clinical Cancer Research.

When heated with lasers, the actively targeted hollow gold nanospheres did eight times more damage to melanoma tumors in mice than did the same nanospheres that gathered less directly in the tumors.

Lab and mouse model experiments demonstrated the first in vivo active targeting of gold nanostructures to tumors in conjunction with photothermal ablation - a minimally invasive treatment that uses heat generated through absorption of light to destroy target tissue. Tumors are burned with near-infrared light, which penetrates deeper into tissue than visible or ultraviolet light.

With hollow gold nanospheres inside melanoma cells, photothermal ablation destroyed tumors in mice with a laser light dose that was 12 percent of the dose required when the nanospheres aren't applied, Li and colleagues report. Such a low dose is more likely to spare surrounding tissue.

Injected, untargeted nanoparticles accumulate in tumors because they are so small that they fit through the larger pores of abnormal blood vessels that nourish cancer, Li said. This "passive targeting" delivers a low dose of nanoparticles and concentrates them near the cell's vasculature.

The researchers packaged hollow, spherical gold nanospheres with a peptide - a small compound composed of amino acids - that binds to the melanocortin type 1 receptor, which is overly abundant in melanoma cells. The targeted nanospheres were actively drawn into the cells through the cell membrane.

When the researchers beamed near-infrared light onto treated cultures, most cells with targeted nanospheres died, and almost all of those left were irreparably damaged. Only a small fraction of cells treated with untargeted nanospheres died. Cells treated only with near-infrared light or only with the nanospheres were undamaged.

Most of the targeted nanospheres in the treated mice gathered in the tumor, with smaller amounts found in the liver and spleen. Most of the untargeted nanospheres gathered in the spleen, then in the liver and then the tumor, demonstrating the selectivity and importance of targeting.

In another group of mice, near-infrared light beamed into tumors with targeted nanospheres destroyed 66 percent of the tumors, but only destroyed 7.9 percent of tumors treated with untargeted nanospheres.

The targeted nanospheres have a number of advantages, said Jin Zhang, Ph.D., professor in the University of California-Santa Cruz Department of Chemistry and developer of the hollow nanospheres. Their size - small even for nanoparticles at 40-50 nanometers in diameter - and spherical shape allow for greater uptake and cellular penetration. They have strong, but narrow and tunable ability to absorb light across the visible and near-infrared spectrum, making them unique from other metal nanoparticles.

The hollow spheres are pure gold, which has a long history of safe medical use with few side-effects, Li said. source

My comment: It's kind of interesting that gold has such a good acceptance in the human body. And also that these nanoparticles gathered in the liver and the spleen. Because it shows where all the other nanoparticles would gather.


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