Friday, July 9, 2010

MYSTERY UNRAVELED: HOW ASBESTOS CAUSES CANCER

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More than 20 million people in the U.S., and many more worldwide, who have been exposed to asbestos are at risk of developing mesothelioma, a malignant cancer of the membranes that cover the lungs and abdomen that is resistant to current therapies. Moreover, asbestos exposure increases the risk of lung cancer among smokers. For the past 40 years researchers have tried to understand why asbestos causes cancer.

The answer appears in a study published in the current issue of the Proceedings of the National Academy of Sciences, U.S.A., Drs. Haining Yang and Michele Carbone at the University of Hawai'i Cancer Research Center led a research team that included collaborators at New York University, University of Chicago, University of Pittsburgh, San Raffaele University of Milano, and the Imperial College in London.

These researchers addressed the paradox of how asbestos fibers that kill cells could cause cancer, since a dead cell should not be able to grow and form a tumor. They found that when asbestos kills cells, it does so by inducing a process called "programmed cell necrosis" that leads to the release of a molecule called high-mobility group box 1 protein (HMGB1). HMGB1 starts a particular type of inflammatory reaction that causes the release of mutagens and factors that promote tumor growth. The researchers found that patients exposed to asbestos have elevated levels of HMGB1 in their serum. Therefore, they state that it may be possible to target HMGB1 to prevent or treat mesothelioma and identify asbestos-exposed cohorts by simple HMGB1 serological testing.

In the article, the researchers propose that by interfering with the inflammatory reaction caused by asbestos and HMGB1, it may be possible to decrease cancer incidence among cohorts exposed to asbestos and decrease the rate of tumor growth among those already affected by mesothelioma. Drs. Yang and Carbone, the lead authors, state that to test this hypothesis, they are now planning a clinical trial in a remote area in Cappadocia, Turkey, where over 50% of the population dies of malignant mesothelioma. If the results are positive, the approach will be extended to cohorts of asbestos-exposed individuals in the U.S.

This research emphasizes the role of inflammation in causing different types of cancers and provides novel clinical tools to identify exposed individuals and prevent or decrease tumor growth. The researchers question if it will be possible to prevent mesothelioma, like colon cancer, simply by taking aspirin or similar drugs that stop inflammation. They are about to test this hypothesis.

University of Hawai’i at Mānoa

WHITER CLOUDS COULD MEAN WETTER LAND

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One proposed emergency fix to halt global warming is to seed clouds over the ocean to make them more reflective, reducing the solar radiation absorbed by the Earth. But the scheme could also change global rainfall patterns, raising concerns of water shortages on land. A new study by the Carnegie Institution, in collaboration with the Indian Institute of Science, suggests that altered atmospheric circulation under the scheme in fact could increase monsoonal rains and cause the continents to become wetter, not drier, on average.

Whitening clouds over the ocean to reflect sunlight is one of several geoengineering schemes proposed to counter global warming. The whitening would be accomplished by reducing the size of the water droplets making up the clouds. "Rain clouds, which have big droplets, tend to be grey and absorb sunlight, whereas clouds with smaller droplets tend to be white and fluffy and reflect more sunlight to space," says co-author Ken Caldeira of the Carnegie Institution's Department of Global Ecology. "In practice this could be done by shooting a fine spray of seawater high into the air, where the tiny salt particles would create condensation nucleii to form small cloud droplets."

To test the climate consequences of doing this, Caldeira and his coauthors used a computer simulation of the global climate system in which atmospheric carbon dioxide concentrations were set at approximately twice that of present day. Cloud droplets over the oceans in the model were reduced in size to make the clouds more reflective. Clouds over land were unaltered. As expected, the whitened clouds reflected more solar radiation and offset the warming effect of the high carbon dioxide levels.

What surprised the researchers, however, was that the model showed that the oceanic clouds caused the land surface to become cooler and wetter on average. In previous climate simulations diminishing solar radiation by geoengineering had reduced precipitation on land. "The drying of the continents has been a major concern with regard to geoengineering," says Caldeira. But in the model the runoff from the continents increased by 7.5% globally, with the effect being strongest in the tropics.

The researchers concluded that the increased precipitation over land was driven by changes in air circulation, similar to the monsoonal pattern that determines rainfall in parts of Asia. "Monsoons occur when air masses over land are warmer than air masses over the ocean, and this draws in cool, moist air from over the ocean which then drops rain over the land," says Caldeira. In the simulations, the reflective oceanic clouds preferentially cooled the air over the oceans relative to land, setting up a monsoonal air flow.

Caldeira stresses that their study, in which all marine clouds worldwide were uniformly whitened, cannot be used to predict the geographic patterns of rainfall that might develop as a result of geoengineering. "In real life, there are only certain parts of the ocean in which you could make the cloud droplets smaller," he says. Areas downwind of land, such as off the east coast of the United States, are already laden with particles of dust and pollution, so adding more particles will not significantly change cloud cover. "An actual deployment would be much patchier than in our study, and the result would therefore be somewhat different. But our basic result calls into question previous assumptions about the impact of this geoengineering scheme. It merits further investigation."

Carnegie Institution

SHAPE-SHIFTING SHEETS AUTOMATICALLY FOLD INTO MULTIPLE SHAPES

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"More than meets the eye" may soon become more than just a tagline for a line of popular robotic toys. Researchers at Harvard and MIT have reshaped the landscape of programmable matter by devising self-folding sheets that rely on the ancient art of origami.

Called programmable matter by folding, the team demonstrated how a single thin sheet composed of interconnected triangular sections could transform itself into a boat- or plane-shape—all without the help of skilled fingers.

Published in the online Early Edition of the Proceedings of the National Academy of Sciences (PNAS) during the week of June 28, lead authors Robert Wood, associate professor of electrical engineering at the Harvard School of Engineering and Applied Sciences (SEAS) and a core faculty member of the Wyss Institute for Biologically Inspired Engineering, and Daniela Rus, a professor in the Electrical Engineering and Computer Science department at MIT and co-director of the CSAIL Center for Robotics, envision creating "smart" cups that could adjust based upon the amount of liquid needed or even a "Swiss army knife" that could form into tools ranging from wrenches to tripods.

"The process begins when we first create an algorithm for folding," explains Wood. "Similar to a set of instructions in an origami book, we determine, based upon the desired end shapes, where to crease the sheet."

The sheet, a thin composite of rigid tiles and elastomer joints, is studded with thin foil actuators (motorized switches) and flexible electronics. The demonstration material contains twenty-five total actuators, divided into five groupings. A shape is produced by triggering the proper actuator groups in sequence.

To initiate the on-demand folding, the team devised a series of stickers, thin materials that contain the circuitry able to prompt the actuators to make the folds. This can be done without a user having to access a computer, reducing "programming" to merely placing the stickers in the appropriate places. When the sheet receives the proper jolt of current, it begins to fold, staying in place thanks to magnetic closures.

"Smart sheets are Origami Robots that will make any shape on demand for their user," says Rus. "A big achievement was discovering the theoretical foundations and universality of folding and fold planning, which provide the brain and the decision making system for the smart sheet."

The fancy folding techniques were inspired in part by the work of co-author Erik Dermaine, an associate professor of electrical engineering and computer science at MIT and one of the world's most recognized experts on computational origami.

While the Harvard and MIT engineers only demonstrated two simple shapes, the proof of concept holds promise. The long-term aim is to make programmable matter more robust and practical, leading to materials that can perform multiple tasks, such as an entire dining utensil set derived from one piece of foldable material.

"The Shape-Shifting Sheets demonstrate an end-to-end process that is a first step towards making everyday objects whose mechanical properties can be programmed," concludes Wood.

(Photo: Harvard U.)

Harvard University

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