Gold's power against autoimmune diseases defined

Mystery solved: Gold's power against autoimmune diseases defined

BOSTON, MA– Gold compounds have been used for the treatment of rheumatoid arthritis and other autoimmune diseases for more than 75 years, but until now, how the metals work has been a mystery. Harvard Medical School researchers report in the Feb. 27 issue of Nature Chemical Biology that special forms of gold, platinum, and other classes of medicinal metals work by stripping bacteria and virus particles from the grasp of a key immune system protein.

"We were searching for a new drug to treat autoimmune diseases," says Brian DeDecker, PhD, HMS post-doctoral student in the Department of Cell Biology and a study co-author. At the time of this work, DeDecker was in the Harvard Medical School Institute of Chemistry and Cell Biology, which uses powerful chemical tools to illuminate complex biological processes and provide new leads for drug development. "But instead we discovered a biochemical mechanism that may help explain how an old drug works."

DeDecker and co-author Stephen De Wall, PhD, undertook a large-scale search for new drugs that would suppress the function of an important component of the immune system, MHC class II proteins, which are associated with autoimmune diseases. MHC class II proteins normally hold pieces of invading bacteria and virus on the surface of specialized antigen presentation cells. Presentation of these pieces alerts other specialized recognition cells of the immune system called lymphocytes, which starts the normal immune response. Usually this response is limited to harmful bacteria and viruses, but sometimes this process goes awry and the immune system turns towards the body itself causing autoimmune diseases such as Juvenile diabetes, Lupus, and rheumatoid arthritis.

During their search through thousands of compounds they found that the known cancer drug, Cisplatin, a drug containing the metal platinum, directly stripped foreign molecules from the MHC class II protein. From there, they found that platinum was just one member of a class of metals, including a special form of gold, that all render MHC class II proteins inactive.

In subsequent experiments in cell culture, gold compounds were shown to render the immune system antigen presenting cells inactive, further strengthening this connection. These findings now give researches a mechanism of gold drug action that can be tested and explored directly in diseased tissues.

In 1890, a German doctor named Robert Koch found that gold effectively killed the bacteria that caused tuberculosis. In the 1930s, based on a widely held but probably erroneous connection at the time between tuberculosis and rheumatoid arthritis, a French doctor, Jacques Forestier, developed the use of gold drugs for the treatment of rheumatoid arthritis. Gold drugs have been used since then as an effective treatment for this and other autoimmune diseases such as Lupus, but treatment can take months for action and sometimes presents severe side effects which have diminished their use in recent years.

With this new understanding of how these metals function, it may now be possible to develop a new generation of gold-based drugs for treating rheumatoid arthritis and other autoimmune diseases that are more effective with fewer side effects. ###

HARVARD MEDICAL SCHOOL http://hms.harvard.edu/Harvard Medical School has more than 7,000 full-time faculty working in eight academic departments based at the School's Boston quadrangle or in one of 47 academic departments at 18 Harvard teaching hospitals and research institutes. Those Harvard hospitals and research institutions include Beth Israel Deaconess Medical Center, Brigham and Women's Hospital, Cambridge Health Alliance, the CBR Institute for Biomedical Research, Children's Hospital Boston, Dana-Farber Cancer Institute, Forsyth Institute, Harvard Pilgrim Health Care, Joslin Diabetes Center, Judge Baker Children's Center, Massachusetts Eye and Ear Infirmary, Massachusetts General Hospital, Massachusetts Mental Health Center, McLean Hospital, Mount Auburn Hospital, Schepens Eye Research Institute, Spaulding Rehabilitation Hospital, and VA Boston Healthcare System.

Contact: John Lacey public_affairs@hms.harvard.edu 617-432-0442 Harvard Medical School

more at autoimmune diseases or biological and biology or medicinal metals and MHC class II proteins or Juvenile diabetes or Science and Lupus or Health and rheumatoid arthritis or bacteria and viruses or gold

RELATED: Keyword, biology. Sunday, December 11, 2005 40,000-year-old human footprints, Sunday, December 18, 2005 warfare in the Mesopotamian world, Sunday, December 18, 2005 Conditions for slavery, Sunday, December 25, 2005 Why Christmas trees are not extinct, Sunday, January 01, 2006 prostaglandins choreograph perturbations, Sunday, January 01, 2006 Cultural differences may explain variations in home remedy use, Sunday, January 08, 2006 Risky Sexual Behaviors in Miami, and Racial Influences on Children’s Care, Sunday, January 22, 2006 Twenty-seven previously unknown species discovered, Sunday, February 12, 2006 Hormone linked to good hearing as we age, Sunday, February 12, 2006 Anti-HIV drug has potential to prevent transmission in women, Sunday, February 12, 2006 Parental Conflict Produces More Than Fleeting Distress for Children, Sunday, February 12, 2006 Facial characteristics indicative of personality traits, say experts, Sunday, February 19, 2006 There's something fishy about human brain evolution, Sunday, February 19, 2006 Marine mammals are on the frontline of failing ocean health, Sunday, February 26, 2006 Study shows that soda consumption increases among adolescent girls as they get older,

Nanoscience study shows that quantum dots 'talk'

Scientists who hope to use quantum dots as the building blocks for the next generation of computers have found a way to make these artificial atoms communicate.

"Essentially, the dots talk to each other," said Ameenah Al-Ahmadi, an Ohio University doctoral student who published the findings with Professor of Physics Sergio Ulloa in a recent issue of the journal Applied Physics Letters.

The dots are tiny, engineered spherical crystals about 5 nanometers in diameter. An average biological cell, in comparison, has a diameter of about 1,000 nanometers. Researchers believe that quantum dots will be extremely useful in developing nanoscale technologies because they are versatile and uniform, which could eliminate possible variations and flaws in materials.

In the recent study, the researchers were the first to use theoretical models to show how light energy shining on quantum dots would prompt them to transfer energy in a "coherent" fashion. They found that when the dots were arranged a certain distance from each other – greater than the radius of the dots – light waves traveled between the nanocrystals in a consistent pattern. In previous research, the light's wavelength would change or become irregular during the energy exchange, which creates a breakdown in communication between quantum dots.

The results suggest that there could be a way to transmit information using light waves, laying the groundwork for a possible optical quantum computer. In this device, light energy would replace the electrical charge currently used to transfer information in conventional computers.

"The idea is to make the (computing) process faster and smaller," said Al-Ahmadi.

The applications of the new quantum dot technology also could include medical imaging. Quantum dots could be injected into the patient, and a device containing more quantum dots could be used to show the position of dots under the skin. Current biology research has had great success with this type of imaging in mouse models, Ulloa said. The dots have fewer side effects than contrast chemicals used in X-rays, and may eventually replace traditional contrast media.

Using light energy instead of electricity also would help keep computer temperatures low, as the light energy does not create as much heat as electrical current, Al-Ahmadi added. ###

The research was funded by the Indiana 21st Century Research and Technology Fund and supplemented by Ohio University's Research Priorities Program. Written by Christina Dierkes.

Contact: Andrea Gibson gibsona@ohio.edu 740-597-2166 Ohio University

more at Nano or Chemistry and nanoparticles or atomic level materials and biologically or Nanotechnology and Nanotech or Science and engineering or molecular and Physics or nanoscale and Bioengineering or quantum dots

Related: Keyword Nanotech Sunday, February 26, 2006 Nano-bots to undertake major tasks?, Sunday, February 19, 2006 Nanotech to improve health care delivery, Sunday, February 19, 2006 nano-canary in the nanotoxicology coalmine, Sunday, December 04, 2005 Nano-cages 'fill up' with hydrogen, Sunday, November 13, 2005 Testing toxicity of nanomaterials, Sunday, October 23, 2005 single-molecule car, 'Nanocar', Sunday, August 28, 2005 Writing at the nanoscale, Thursday, May 26, 2005 discontinuous palladium, siloxane self-assembled monolayer, Sunday, May 08, 2005 Center for Nanoscale Materials, Monday, April 25, 2005 Nanomagnets, Nanocomposite, Monday, March 21, 2005 porphyrin tubes may lead to new nanodevices, inexpensive hydrogen fuel