Green Tea

A new study from the University of Michigan Health System suggests that a compound in green tea may provide therapeutic benefits to people with rheumatoid arthritis. Credit: Stockphoto Science Daily


The compound from green tea was found to suppress the inflammatory products in the connective tissue of people with rheumatoid arthritis.

The study, presented April 29 at the Experimental Biology 2007 in Washington, D.C., looks at a potent anti-inflammatory compound derived from green tea. Researchers found that the compound – called epigallocatechin-3-gallate (EGCG) – inhibited the production of several molecules in the immune system that contribute to inflammation and joint damage in people with rheumatoid arthritis.

To conduct the research, the scientists isolated cells called synovial fibroblasts from the joints of patients with rheumatoid arthritis. These fibroblasts – cells that form a lining of the tissue surrounding the capsule of the joints – then were cultured in a growth medium and incubated with the green tea compound.

The fibroblasts were then stimulated with pro-inflammatory cytokine IL-1b, a protein of the immune system known to play an important role in causing joint destruction in people with rheumatoid arthritis. The researchers looked at whether the green tea compound has the capability to block the activity of two potent molecules, IL-6 and cyclooxygenase-2 (COX-2), which also are actively involved in causing boneerosion in the joints of people with rheumatoid arthritis.

When untreated cells were stimulated with IL-1b, a sequence of molecular events occurred that resulted in production of the bone-destructive molecules. But the scientists found that pre-incubation with EGCG was capable of inhibiting the production of these molecules. EGCG also inhibited the production of prostaglandin E2, a hormone-like substance that causes inflammation in the joints.

The cell signaling pathways that regulate levels of these immune system molecules under both normal and rheumatoid arthritis situations are well studied, and the researchers were able to trace the effects of the green tea compound infusion to see that it worked by inhibiting these pathways.

Green Tea Compound, May Be A Therapy For Rheumatoid Arthritis
Rheumatoid Arthritis And The Impact Of Genetic Factors On Mortality
_______________________________________________________
_______________________________________________________

Weighing living cells

New MIT technique weighs single living cells.
For the first time, MIT researchers have found a way to measure the mass of single cells with high accuracy.

The new technique, which is based on a micromechanical detector, could allow researchers to develop inexpensive, portable diagnostic devices and might also offer a unique glimpse into how cells change as they undergo cell division.

Unlike conventional methods, the MIT technique allows cells to remain in fluid while they are being measured, opening up a new realm of possible applications, says Scott Manalis, senior author of a paper on the work that will appear in the April 26 issue of Nature.

In addition to weighing cells, the technology can be used to "weigh nanoparticles or sub-monolayers of biomolecules with a resolution in solution that is six orders of magnitude more sensitive than commercial mass sensor methods. One direction we're pursuing is mass-based flow cytometry, a way to weigh and count specific cells," said Manalis, an associate professor in MIT's Departments of Biological Engineering and Mechanical Engineering.

Current mass-measurement methods achieve a resolution down to a zeptogram (10 to the minus 21 grams) but only work with non-living things because the procedure must be performed inside a vacuum. So, the MIT researchers decided to turn the conventional system inside out.

In the traditional method, the molecules to be weighed are placed on top of a tiny slab, or cantilever, made of silicon. The slab vibrates at its resonant frequency (the frequency at which the material naturally tends to vibrate) inside a vacuum. When a molecule sits on the slab, the frequency changes slightly, and the mass of the molecule can be calculated by measuring that change.

This measurement must be performed in a vacuum to prevent air (or fluid) from interfering with the frequency of oscillation. However, cells cannot survive in a vacuum, so they must be measured in fluid, which diminishes the accuracy of the measurement.

The researchers solved this dilemma by placing the fluid containing the sample inside the silicon slab, which still oscillates within a vacuum surrounding it. The biological sample is pumped through a microchannel that runs across the slab, without impairing its ability to vibrate.

"The resonator is sealed in a tiny vacuum cavity inside the chip, so there is virtually no resistance to the vibration," said co-lead author Thomas Burg, a research associate in biological engineering. "This lets us measure a mass change, say 10 parts in a billion, of the already very light microcantilever."

So far, the researchers have weighed particles with a resolution down to slightly below a femtogram (10 to the minus 15 grams), but Manalis believes that with refinements, the sensitivity could potentially be lowered by several orders of magnitude within a few years. "Every step along the way will open up new possibilities."

The researchers can also measure the mass density of particles or cells "by varying the density of the surrounding solution," said Michel Godin, co-lead author.

The research team is already looking into several applications for the new technique. One area of great promise is creating a device that would mimic the cell-counting capabilities of flow cytometers. However, flow cytometry devices, which work by bouncing light off a flowing stream of cells, are too large and expensive to be useful in developing countries.

A tiny chip that could count cells using the new MIT weighing method would be a "cheap and robust" alternative to commercially available flow cytometers, which typically cost more than $20,000, Manalis said. "Since the device is batch-fabricated by conventional semiconductor processing techniques, it could potentially be used in a disposable format."

"Simply put, a cheap, simple CD4 counting device that can be used by a community health worker … would be a breakthrough advance in global health," according to Rodriguez.

Manalis is also planning a collaboration with MIT associate professor of biology Angelika Amon, who is interested in studying how the mass density of a single cell changes as it goes through cell division. Using the new method, scientists can ultimately trap a single cell and observe it over a long period of time. Changes in mass could correlate to production of proteins, offering a new way to study what the cell does during division, Manalis said.

Another application of the new technology is to measure small particles, or beads. It's important to know the size of particles used in paint, drug-delivery devices, coatings and nanocomposite materials, said Manalis, who added that the new technology could become the "gold standard" way to measure these particles one by one.

This illustration shows an artistic depiction of the concept that enables measuring the mass of a single bacterium and single nanoparticles in fluid with a very high resolution. A hollow resonator, represented by a hollow, fluid-filled guitar, vibrates while small particles, represented here by a bacterium, flow through it. As the particles flow through the resonator, they change the frequency (tone) of the vibration. (Credit: Image courtesy Thomas Burg)

Other authors on the Nature paper are Scott Knudsen, MIT postdoctoral associate in biological engineering; Wenjiang Shen, Greg Carlson and John S. Foster of Innovative Micro Technology in Santa Barbara, Calif.; and Ken Babcock of Innovative Micro Technology and Affinity Biosensors in Santa Barbara.

The research was funded by the National Institutes of Health Cell Decision Process Center, the Institute for Collaborative Biotechnologies from the U.S. Army Research Office, the Air Force Office of Sponsored Research, the National Science Foundation and the Natural Sciences and Engineering Research Council of Canada.
________________________________________________________
________________________________________________________
The Max Planck Society Press Releases
Everything starts with Recognition 23rd April 2007
Asymmetry due to Perfect Balance 25th April 2007
Electrons Caught in the Act of Tunnelling 12th April 2007
________________________________________________________
________________________________________________________