Duke University Medical Center, May 3, 2010  —  A newly discovered strain of an airborne fungus has caused several deaths in Oregon and seems poised to move into California and other adjacent areas, according to scientists at Duke University Medical Center.

“This novel fungus is worrisome because it appears to be a threat to otherwise healthy people,” said Edmond Byrnes III, a graduate student in the Duke Department of Molecular Genetics and Microbiology. “Typically, we see this fungal disease associated with transplant recipients and HIV-infected patients, but that is not what we are seeing.” Byrnes and other Duke co-authors work in the laboratory of senior author Joseph Heitman, M.D., Ph.D., and chair of the Department of Molecular Genetics and Microbiology.

Their new work on the emergence and virulence of the new genotypes of Cryptococcus gattii fungi in the United States was published online in PLoS Pathogens on April 22.

The mortality rate for recent C. gattii cases in the Pacific Northwest is running at approximately 25 percent out of 21 cases analyzed in the United States, compared to a mortality rate of 8.7 percent out of 218 cases in British Columbia, Canada, the researchers said. Most have a more complicated clinical course than people infected with the more common Cryptococcus neoformans.

Because the strain is so virulent when it infects some humans and animals, the researchers are calling for greater awareness and vigilance. Testing involves culturing the fungus and then sequencing its DNA to learn whether it is the virulent or more benign strain, which could affect treatment plans.

Some strains of C. gattii are not more virulent than C. neoformans, for example, but doctors need to know what type they are dealing with, Byrnes said. Using molecular techniques, the geneticists uncovered clues that showed the Oregon-only fungal type most likely arose recently, in addition to an outbreak of C. gattii that began in Canada in 1999 that has now spread into Washington and Oregon.

Symptoms can appear two to several months after exposure, and may include a cough lasting weeks, sharp chest pain, shortness of breath, headache (related to meningitis), fever, nighttime sweats and weight loss. In animals the symptoms are a runny nose, breathing problems, nervous system problems and raised bumps under the skin. While C. gattii can be treated, it cannot be prevented; there is no vaccine.

The new type of Cryptococcus gattii reproduces both sexually and asexually. The more virulent strain may have genetically recombined with related but less harmful strains. This novel genotype is highly virulent compared with similar isolates of Cryptococcus that are not causing disease outbreaks.

The researchers found that the novel genotype (VGIIc) is now a major source of Cryptococcus gattii illness in Oregon. Because C. gattii types had been found in tropical areas before, co-lead author Wenjun Li, M.D., Ph.D., of Duke Molecular Genetics and Microbiology, speculates that environmental changes may be responsible for the evolution and emergence of this pathogen.

Determining the exact origin of the VGIIc type is difficult, and sampling thus far has failed to turn up isolates in Oregon soil, water or trees.

“We are trying to put together the evolutionary story of where these types come from by closely studying the genetics of all samples possible,” said Yonathan Lewit, a research associate also in Duke Molecular Genetics and Microbiology. He said that cell components called mitochondria may play a role in the increased virulence of certain types.

VGIIc, the new Oregon strain, has yielded dozens of isolates in many specimens, including from domesticated animals: cats, dogs, an alpaca and a sheep. “Most of those are nonmigratory animals,” Byrnes said, explaining that the animals probably didn’t bring the pathogen from some other region, and most likely acquired it locally.

Other authors include Hansong Ma, Kerstin Voelz and Robin May of the Department of Molecular Pathobiology at the University of Birmingham, United Kingdom; Ping Ren and Vishnu Chaturvedi of the Mycology Laboratory at Wadsworth Center in Albany, N.Y.; Dee Carter of the Department of Molecular and Microbial Biosciences, the University of Sydney, Australia; and Robert Bildfell of the Department of Biomedical Sciences, Oregon State University, Corvallis.

This work was supported by National Institutes of Health/National Institute of Allergy and Infectious Diseases grants.

 

Story Source:

Adapted from materials provided by Duke University Medical Center.

The molecules in the majority form the superstructure while the minority remain disordered. (Credit: Image courtesy of University of Liverpool)

 

 

University of Liverpool, Great Britain   —  Research at the University of Liverpool has found how mirror-image molecules gain control over each other and dictate the physical state of superstructures.

The research team studied ‘chiral’ or ‘different-handed’ molecules which are distinguishable by their inability to be superimposed onto their mirror image. Such molecules are common – proteins use just one mirror form of amino acids and DNA, one form of sugars. Chirality leads to profound differences in the way a molecule functions – for example, drugs such as thalidomide can have positive effects on a patient but can prove harmful in their mirror image form.

Molecules can also assemble in large numbers and form ‘superstructures’ such as snowflakes which are created from large numbers of water molecules. When chiral molecules assemble they can create ‘handed’ superstructures; for example left-handed molecules can assemble together to make a left-handed superstructure. The Liverpool team studied this process in detail by assembling molecules at flat surfaces and using imaging techniques to map the formation of superstructures at nanoscale level.

Before now, scientists have not known whether, in systems containing both left-handed and right-handed molecules, one mirror-form of a molecule could take supremacy over its opposite number in the creation of superstructures, dictating their physical state and chemical and biological properties.

The research found that when equal numbers of mirror-molecules are present at the surface, they organize into separate left and right-handed superstructures, each with distinctly different properties. Crucially, a small imbalance in the population leads to a dramatic difference and only the molecules in the majority assemble into its superstructure, while the minority is left disordered at the surface and unable to create advanced molecular matter.

Professor Rasmita Raval from the University’s Surface Science Research Centre said: “We were surprised at these results. All perceived wisdom was that the left and right-handed molecules would simply create their respective superstructures in quantities that reflected the molecular ratio – that is, we would observe proportional representation. Instead, what we obtained was a kind of ‘molecular democracy’ that worked on a ‘first-past-the-post’ system where the majority population wrested chiral control of the superstructures and the minority was left disorganized.”

Theoretical modeling carried out by the University of Eindhoven in the Netherlands found that this behavior arises from the effects of entropy, or disorder, which leads the chiral molecules in the majority to preferentially organize into their superstructure.

The work has important implications in the pharmaceuticals industry and could lead to the development of surface processes to enable separation of drugs and products that are currently difficult to purify. The research also introduces the possibility that assembly processes at surfaces may naturally have led to the evolution of proteins and DNA – the molecules of life – containing just one mirror form of amino acids and sugars.

The research, in collaboration with the University of Eindhoven, is published in Nature Chemistry.

 

 

Story Source:

Adapted from materials provided by University of Liverpool.


Journal Reference:

  1. 1.                     Sam Haq, Ning Liu, Vincent Humblot, A. P. J. Jansen & Rasmita Raval. Drastic symmetry breaking in supramolecular organization of enantiomerically unbalanced monolayers at surfaces. Nature Chemistry, 2009; 1 (5): 409 DOI: 10.1038/nchem.295

Genome Institute of Singapore, May 3, 2010  —  Scientists at the Genome Institute of Singapore (GIS) have recently generated significant single cell expression data crucial for a detailed molecular understanding of mammalian development from fertilization to embryo implantation, a process known as the preimplantation period. The knowledge gained has a direct impact on clinical applications in the areas of regenerative medicine and assisted reproduction.

This study, published in Developmental Cell on April 20, 2010, is the first of its kind to apply single cell gene expression analysis of many genes to hundreds of cells in a developmental system.

Using the new BioMark microfluidic technology and the mouse preimplantation embryo as a model, the scientists were able to study the expression of 48 genes from individual cells and applied this to analyze over 600 individual cells from the 1-cell to the 64-cell stage of preimplantation development. This high throughput single cell research methodology provides the scientists with the ability to detect dynamic patterns in cellular behaviour, which is unprecedented in the field. Significantly, the findings of the study resolves some of the arguments pertaining to cellular differentiation events and places fibroblast growth factor signalling as the primary event in the later cell fate decisions.

Executive Director at the GIS, a biomedical research institute of the Agency for Science, Technology and Research (A*STAR), Professor Edison Liu said,

“This remarkable work by Guoji Guo, Mikael Huss, Paul Robson and colleagues uses new microgenomic technologies to map, over time, how a single cell decides to permanently become different parts of an embryo. Within one division, cells commit to specific developmental lineages by expressing defined sets of genes. This research now opens the possibility of assessing the genetic triggers for fate determination of individual cells in developmental time. On another level, this work highlights the importance of new microtechnologies in advancing the understanding of early embryonic events. ”

Professor Davor Solter, Senior Principal Investigator of the Institute of Medical Biology, A*STAR, added, “This is a real technological tour de force. The authors investigated changes in expression of multiple genes on the single cell level during preimplantation mouse development. They clearly demonstrated gradual and stochastic lineage allocation and absence of predetermination. These results conclusively resolved one of the hotly debated issues in mammalian development and provided important new insight into the mechanism which regulates early development in mammals.”

“These are important findings. The team at GIS provided a new look into the complex and little-understood process of early embryo development. It also demonstrates the power of single cell gene expression. It is clear that individual cells and small groups of cells behave differently than the aggregate population, and these differences are key to understanding the biology of the system as a whole.” said Gajus Worthington, president and chief executive officer of Fluidigm. “It always provides a special thrill when researchers use the capabilities of Fluidigm’s technology to bring insight to the body of scientific knowledge.”

The Preimplantation period involves the first cellular differentiation events in mammalian development including the formation of pluripotent cell from where embryonic stem (ES) cells are derived. Being one of the simplest mammalian developmental systems to study, it can provide comprehensive understanding of the complex molecular control of reprogramming and cell fate decisions.

 

Story Source:

Adapted from materials provided by Agency for Science, Technology and Research (A*STAR), Singapore.

GoogleNews.com, May 3, 2010 – A potentially deadly strain of fungus is spreading among animals and people in the northwestern United States and the Canadian province of British Columbia, researchers reported on Thursday.

The airborne fungus, called Cryptococcus gattii, usually only infects transplant and AIDS patients and people with otherwise compromised immune systems, but the new strain is genetically different, the researchers said.

“This novel fungus is worrisome because it appears to be a threat to otherwise healthy people,” said Edmond Byrnes of Duke University in North Carolina, who led the study.

“The findings presented here document that the outbreak of C. gattii in Western North America is continuing to expand throughout this temperate region,” the researchers said in their report, published in the Public Library of Science journal PLoS Pathogens here

“Our findings suggest further expansion into neighboring regions is likely to occur and aim to increase disease awareness in the region.”

The new strain appears to be unusually deadly, with a mortality rate of about 25 percent among the 21 U.S. cases analyzed, they said.

“From 1999 through 2003, the cases were largely restricted to Vancouver Island,” the report reads.

“Between 2003 and 2006, the outbreak expanded into neighboring mainland British Columbia and then into Washington and Oregon from 2005 to 2009. Based on this historical trajectory of expansion, the outbreak may continue to expand into the neighboring region of Northern California, and possibly further.”

The spore-forming fungus can cause symptoms in people and animals two weeks or more after exposure. They include a cough that lasts for weeks, sharp chest pain, shortness of breath, headache, fever, nighttime sweats and weight loss.

It has also turned up in cats, dogs, an alpaca and a sheep.

Freezing can kill the fungus and climate change may be helping it spread, the researchers said.

Experts explain green tea’s potential benefits for everything from fighting cancer to helping your heart

Reviewed by Louise Chang, MD

WebMD.com, May 3, 2010, by Julie Edgar  –  More than a decade’s worth of research about green tea’s health benefits — particularly its potential to fight cancer and heart disease — has been more than intriguing, as have limited studies about green tea’s role in lowering cholesterol, burning fat, preventing diabetes and stroke, and staving off dementia.

“I believe in green tea based on everything written about it,” says Katherine Tallmadge, RD, LD, a nutritionist and spokeswoman for the American Dietetic Association. “Green tea, white tea, black tea — I like all of them.”

Still, real-world evidence is lacking; most of the consistent findings about green tea’s health benefits have come out of the lab.

The few large-scale human studies that have focused on green tea’s impact on heart disease and cancer are promising, but many of those were conducted in the East, where green tea is a dietary mainstay. The outcomes are likely influenced by other lifestyle factors such as high consumption of fish and soy protein, says cardiologist Nieca Goldberg, MD, a spokeswoman for the American Heart Association and medical director of the New York University Women’s Heart Center.

But Goldberg agrees with other health professionals: green tea has important antioxidants and compounds that help in maintaining good health.

Green Tea’s Powerful Antioxidants

Green tea’s antioxidants, called catechins, scavenge for free radicals that can damage DNA and contribute to cancer, blood clots, and atherosclerosis. Grapes and berries, red wine, and dark chocolate also have potent antioxidants.

Because of green tea’s minimal processing — its leaves are withered and steamed, not fermented like black and oolong teas — green tea’s unique catechins, especially epigallocatechin-3-gallate (EGCG), are more concentrated.

But there’s still a question of how much green tea you need to drink to reap its health benefits. EGCG is not readily “available” to the body; in other words, EGCG is not always fully used by the body.

“We must overcome the issue of poor bioavailability [and other issues] in order to get the most out of their benefits,” says Tak-Hang Chan, PhD, professor emeritus in the department of chemistry at McGill University in Montreal. Chan has studied the use of a synthetic form of EGCG in shrinking prostate cancer tumors in mice, with success.

Green Tea vs. Cancer

Marji McCullough, ScD, RD, the American Cancer Society’s strategic director of nutritional epidemiology, says human studies haven’t yet proven what researchers like Chan have discovered in the lab: green tea’s EGCG regulates and inhibits cancer growth and kills cells that are growing inappropriately.

“Epidemiologically, one of the challenges is finding populations that drink enough green tea and have for a long time,” she says. “With cancer, it’s always difficult to find the exposure time,” or the point at which cancer cells begin to develop.

Green Tea vs. Cancer continued…

Still, it’s difficult not to be intrigued by a few human studies that have shown that drinking at least two cups of green tea daily inhibits cancer growth.

One of them, a study conducted in Japan that involved nearly 500 Japanese women with Stage I and Stage II breast cancer, found that increased green tea consumption before and after surgery was associated with lower recurrence of the cancers.

Studies in China have shown that the more green tea that participants drank, the less the risk of developing stomach cancer, esophageal cancer, prostate cancer, pancreatic cancer, and colorectal cancer.

Finally, a recent analysis of 22 studies that probed the correlation between high tea consumption and reduced risk for lung cancer concluded that by increasing your daily intake of green (not black) tea by two cups may reduce the risk of developing lung cancer by 18%.

Is Green Tea Good for Your Heart?

It seems to be, but there are conflicting results of a few epidemiological studies conducted in the East and West.

In a study that involved 500 Japanese men and women, researchers found that drinking at least four cups of green tea every day may be related to the reduced severity of coronary heart disease among the male participants.

A Dutch study of more than 3,000 men and women found that the more tea consumed, the less severe the clogging of the heart’s blood vessels, especially in women.

As Goldberg suggests, lifestyle and overall diet are critical to the outcomes of these studies.

But green tea’s antioxidants are dilators, she says, because they improve the flexibility of blood vessels and make them less vulnerable to clogging — and antioxidant-rich blueberries and pomegranates do the same.

“I think people should know these are important studies, that everyday foods that are an option may actually have health benefits,” Goldberg says. “I think green tea, because of its antioxidant value, may have heart benefits, but it’s not something we regularly prescribe to people, because there isn’t as much evidence as there is in exercise’s ability to improve heart health.”

Green Tea and Weight

Green tea and its extract have been shown to fight obesity and lower LDL “bad” cholesterol — two risk factors for heart disease and diabetes — but in very limited studies. One study in the Netherlands and a study in Japan showed that green tea did both.

In the Dutch study, participants who drank caffeinated green tea lost more weight, but even those who typically drank the decaf variety saw a decrease in their waistlines and body weight. Researchers speculated that the caffeine helps with fat oxidation.

In the Japanese study, 240 men and women were given varying amounts of green tea extract for three months. Those who got the highest amount lost fat and weight and had lower blood pressure and lower LDL “bad” cholesterol.

Green Tea Straight Up

Taking weight loss supplements that contain green tea extract probably won’t hurt, unless you have liver problems.

But the best way to get the most out of green tea — even if your main goal is losing weight — is to drink it.

“Taken altogether, the evidence certainly suggests that incorporating at least a few cups of green tea every day will positively affect your health,” says Diane McKay, PhD, a Tufts University scientist who studies antioxidants. “It’s not going to cure anything and it shouldn’t be consumed as a drug, but it can complement the rest of the diet.”

McCullough bears the same reminder: eat your fruits, vegetables, grains, seeds, and nuts — and go ahead, drink as much green tea as you want.

“I don’t think it can hurt to drink it. I’d focus on dietary sources rather than supplements because there are several compounds in green tea that might need to be consumed together. We just don’t know yet,” she says.