New processes for cost-efficient solar cell production

ScienceDaily (Sep. 19, 2012) — The competition in the photovoltaics market is fierce. When it comes to price, Asian manufacturers are frequently ahead of the competition by a nose. Now, Fraunhofer researchers are designing new coating processes and thin layer systems that, if used, could help to reduce the price of solar cells significantly.

Scientists will unveil a few of these new processes at the EU PVSEC trade show in Frankfurt from September 25 to 28.

Many people answer with a resounding "yes!" when asked if they want environmentally-friendly solar cell-based power -- though it should be inexpensive. For this reason, a veritable price war is raging among the makers of photovoltaic cells. Above all, it are the cheap products of Asian origin that are making life tough for domestic manufacturers. Tough, that is, until now: the researchers at the Fraunhofer Institute for Surface Engineering and Thin Films IST in Braunschweig are providing support to these companies. They are engineering coating processes and thin film systems aimed at lowering the production costs of solar cells drastically.

Hot wires instead of plasma

The photovoltaic industry is pinning its hopes particularly on high-efficiency solar cells that can achieve efficiencies of up to 23 percent. These "HIT" cells (Heterojunction with Intrinsic Thin layer) consist of a crystalline silicon absorber with additional thin layers of silicon. Until now, manufacturers used the plasma-CVD process (short for Chemical Vapor Deposition) to apply these layers to the substrate: the reaction chamber is filled with silane (the molecules of this gas are composed of one silicon and four hydrogen atoms) and with the crystalline silicon substrate. Plasma activates the gas, thus breaking apart the silicon-hydrogen bonds. The now free silicon atoms and the silicon-hydrogen residues settle on the surface of the substrate. But there's a problem: the plasma only activates 10 to 15 percent of the expensive silane gas; the remaining 85 to 90 percent are lost, unused. This involves enormous costs.

The researchers at IST have now replaced this process: Instead of using plasma, they activate the gas by hot wires. "This way, we can use almost all of the silane gas, so we actually recover 85 to 90 percent of the costly gas. This reduces the overall manufacturing costs of the layers by over 50 percent. The price of the wire that we need for this process is negligible when compared to the price of the silane," explains Dr. Lothar Schäfer, department head at IST. "In this respect, our system is the only one that coats the substrate continously during the movement -- this is also referred to as an in-line process." This is possible since the silicon film grows up at the surface about five times faster than with plasma CVD -- and still with the same quality of layer. At this point, the researchers are coating a surface measuring 50 by 60 square centimeters; however, the process can be easily scaled up to the more common industry format of 1.4 square meters. Another advantage: The system technology is much easier than with plasma CVD, therefore the system is substantially cheaper. Thus, for example, the generator that produces the electric current to heat the wires only costs around one-tenth that of its counterpart in the plasma CVD process.

In addition, this process is also suitable for thin film solar cells. With a degree of efficiency of slightly more than ten percent, these have previously shown only a moderate pay-off. However, by tripling the solar cells (i.e., by putting three cells on top of each other) the degree of efficiency spikes up considerably. But there is another problem: Because each of the three cells is tied to considerable material losses using the plasma CVD coatings, the triple photovoltaic cells are expensive. So the researchers see another potential use for their process: the new coating process would make the cells much more cost-effective. Triple cells could even succeed over the long term if the rather scarce but highly efficient germanium is used. However, germanium is also very expensive: in order for it to be a profitable choice, one must be able to apply the layers while losing as little of the germanium as possible -- by using the hot-wire CVD process, for instance.

Saving 35 percent in the sputter process for transparent conductive oxide

The power generated by photovoltaic cells has to be able to flow out, in order for it to be used. To do so, usually a contact grid of metal is evaporated onto the solar cells, which conducts the resulting holes and electrons. But for HIT cells, this grid is insufficient. Instead, transparent, conductive layers -- similar to those in an LCD television -- are needed on the entire surface.

This normally happens through the sputter process: ceramic tiles, made from aluminum-doped zinc or indium-zinc oxide, are atomized. The dissolved components attach to the surface, thereby producing a thin layer. Unfortunately, the ceramic tiles are also quite expensive. Therefore, the researchers at IST use metallic tiles: They are 80 percent cheaper than their ceramic counterparts. An electronic control ensures that the metal tiles do not oxidize. Because that would otherwise change the manner in which the metal sputters. "Even though the control outlay is greater, we can still lower the cost of this production process by 35 percent for 1.4 square meter coatings," says Dr. Volker Sittinger, group manager at IST.

The research team intends to combine both processes over the long term, in order to make thin-coated solar cells more cost-effective and ultimately, more profitable. "You can produce all silicon layers using the hot-wire CVD, and all transparent conductive layers through sputtering with metal tiles. In principle, these processes should also be suitable for large formats," states Sittinger. However, the processes being used are not production processes quite yet: Even if the researchers already apply the processes to a countless number of square centimeters, it will still take about three to five years until they can be used in the production of solar cells.

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19 Sep, 2012

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Modern DNA techniques applied to nineteenth-century potatoes

ScienceDaily (Sep. 19, 2012) — Researchers led by Professor Bruce Fitt, now at the University of Hertfordshire, have used modern DNA techniques on late nineteenth-century potatoes to show how the potato blight may have survived between cropping seasons after the Irish potato famine of the 1840s.

Late blight of potato is caused by the microorganism, Phytophthora infestans, which rapidly destroys the leaves of potato crops and was responsible for the infamous Irish potato famine of the 1840s that left over one million people dead and another one million Irish emigrating. With growing concerns over food shortages and climate change, late blight remains a serious disease problem in current potato production and has also emerged as a significant disease threat to the organic tomato industry.

In the research paper published in Plant Pathology, DNA was extracted from the Rothamsted potato samples that had been dried, ground and stored in glass bottles in the nineteenth century. The DNA was then analysed for the presence of the potato blight pathogen.

Bruce Fitt, Professor of Plant Pathology at the University of Hertfordshire and formerly at Rothamsted Research, said: "It was the foresight of two nineteenth-century plant scientists to archive potato samples from their experiment that has enabled us to apply modern DNA techniques to better understand late potato blight and the implications for today's food security. The analysis of these late nineteenth-century potato samples is the earliest proof of how this disease survived between seasons in England."

The findings of this research has proved that the DNA technique applied to the potato samples is a very useful tool in plant disease diagnosis to test seed potatoes or tomato transplants for the presence of the late blight pathogen. This technique can be further developed for testing for other diseases found in different plants which affect food production.

Bruce continued: "Using modern DNA techniques to detect and quantify the pathogen in potatoes enables us to better understand the spread of potato late blight. This disease is still a serious threat to worldwide potato production."

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Journal Reference:

1. J. B. Ristaino, C. H. Hu, B. D. L. Fitt. Evidence for presence of the founder Ia mtDNA haplotype of Phytophthora infestans in 19th century potato tubers from the Rothamsted archives. Plant Pathology, 2012; DOI: 10.1111/j.1365-3059.2012.02680.x

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19 Sep, 2012

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Major changes needed to protect Australia's species and ecosystems

ScienceDaily (Sep. 18, 2012) — A landmark study has found that climate change is likely to have a major impact on Australia's plants, animals and ecosystems that will present significant challenges to the conservation of Australia's biodiversity.

The comprehensive study by CSIRO highlights the sensitivity of Australia's species and ecosystems to climate change, and the need for new ways of thinking about biodiversity conservation.

"Climate change is likely to start to transform some of Australia's natural landscapes by 2030," lead researcher, CSIRO's Dr Michael Dunlop said.

"By 2070, the ecological impacts are likely to be very significant and widespread. Many of the environments our plants and animals currently exist in will disappear from the continent. Our grandchildren are likely to experience landscapes that are very different to the ones we have known."

Dr Dunlop said climate change will magnify existing threats to biodiversity, such as habitat clearing, water extraction and invasive species. Future climate-driven changes in other sectors, such as agriculture, water supply and electricity supply, could add yet more pressure on species and ecosystems.

"These other threats have reduced the ability of native species and ecosystems to cope with the impacts of climate change," Dr Dunlop said.

One of the challenges for policy and management will be accommodating changing ecosystems and shifting species.

The study suggests the Australian community and scientists need to start a rethink of what it means to conserve biodiversity, as managing threatened species and stopping ecological change becomes increasingly difficult.

"We need to give biodiversity the greatest opportunity to adapt naturally in a changing and variable environment rather than trying to prevent ecological change," Dr Dunlop said.

The study highlights the need to start focusing more on maintaining the health of ecosystems as they change in response to climate change, from one type of ecosystem to another.

'This could need new expectations from the community, possibly new directions in conservation policy, and new science to guide management," Dr Dunlop said.

"To be effective we also need flexible strategies that can be implemented well ahead of the large-scale ecological change. It will probably be too late to respond once the ecological change is clearly apparent and widespread."

The study found the National Reserve System will continue to be an effective conservation tool under climate change, but conserving habitat on private land will be increasingly important to help species and ecosystems adapt.

The team of researchers from CSIRO carried out modelling across the whole of Australia, as well as detailed ecological analysis of four priority biomes, together covering around 80 per cent of Australia.

The study was funded by the Australian Government Department of Sustainability, Environment, Water, Population and Communities, the Department of Climate Change and Energy Efficiency and the CSIRO Climate Adaptation Flagship.

Further information: http://www.csiro.au/Organisation-Structure/Flagships/Climate-Adaptation-Flagship/adapt-national-reserve-system.aspx

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19 Sep, 2012

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Birth is no reason to go to hospital, review suggests

ScienceDaily (Sep. 19, 2012) — A new Cochrane Review concludes that all countries should consider establishing proper home birth services. They should also provide low-risk pregnant women with information enabling them to make an informed choice. The review has been prepared by senior researcher, statistician Ole Olsen, the Research Unit for General Practice, University of Copenhagen, and midwifery lecturer PhD Jette Aaroe Clausen.

In many countries it is believed that the safest option for all women is to give birth in hospital. However, observational studies of increasingly better quality and in different settings suggest that planned home birth in many places can be as safe as planned hospital birth and with less intervention and fewer complications.

"If home birth is going be an attractive and safe option for most pregnant women, it has to be an integrated part of the health care system," Ole Olsen says and adds, "In several Danish regions the home birth service has been very well organized for several years. This is not the case everywhere in the world."

The updated Cochrane Review concludes that there is no strong evidence from experimental studies (randomized trials) to favor either planned hospital birth or planned home birth for low-risk pregnant women. At least not as long as the planned home birth is assisted by an experienced midwife with collaborative medical back up in case transfer should be necessary.

Fewer interventions in home birth

Routines and easy access to medical interventions may increase the risk of unnecessary interventions in birth explaining why women who give birth at home have a higher likelihood for a spontaneous labour. There are 20-60 per cent fewer interventions, for example fewer cesarean sections, epidurals and augmentation among those women who plan a homebirth; and 10-30 per cent fewer complications, for example post partum bleeding and severe perineal tears.

"Patience is important if women want to avoid interference and give birth spontaneously," says Jette Aaroe Clausen. "At home the temptation to make unnecessary interventions is reduced. The woman avoids for example routine electronic monitoring that may easily lead to further interventions in birth."

Jette Aaroe Clausen adds that interventions in childbirth are common in many countries, but also that there is a growing concern internationally because interventions may lead to iatrogenic effects; iatrogenic effects meaning unintended consequences of the intervention. Routine electronic monitoring may for example lead to more women having artificial rupture of membranes which in turn can lead to more interventions.

Evidence and human rights

While the scientific evidence from observational studies has been growing, the European Court of Human Rights in Strasbourg in the case Ternovszky versus Hungary has handed down a judgment stating that "the right to respect for private life includes the right to choose the circumstances of birth." This is quoted in the review.

Thus the conclusions of the review are based on human rights and ethics as well as on results from the best available scientific studies.

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Journal Reference:

1. Ole Olsen, David Jewell. Home versus hospital birth. The Cochrane Library, 12 SEP 2012 DOI: 10.1002/14651858.CD000352

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19 Sep, 2012

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Tackling 'frequent flyers' won't solve the rising emergency hospital admissions problem

ScienceDaily (Sep. 18, 2012) — Patients who are regularly admitted to hospital as emergencies (known as 'frequent flyers') make up a large proportion of admissions, but focusing just on them won't solve the problem of rising admissions, say experts on bmj.com today.

Martin Roland and Gary Abel from the Cambridge Centre for Health Services Research argue that this is one of several misconceptions about emergency admissions that must be tackled if we are to reduce the number of people being admitted as emergencies. Around the world, the pressure to reduce healthcare costs is huge. Emergency hospital admissions are an expensive aspect of care and rates have been rising for several years, particularly among the elderly and those with several conditions (co-morbidities).

In the UK, many initiatives have been set up to reduce emergency admissions, mainly in primary care and with a focus on high risk patients who are thought to use a disproportionate share of resources.

But Roland and Abel argue that there are "some fundamental flaws" in this approach. Exclusively focusing on high risk patients won't solve the problem, they say, as data show that most admissions come from low and medium risk groups. Instead they suggest interventions may need to be targeted on larger population groups, such as elderly patients.

They also challenge the widespread view that improving primary care could prevent many emergency admissions and suggest that some of the rise in admissions may be due to the introduction of four hour waiting targets in A&E. They say that primary and secondary care doctors need to work together to achieve a common set of goals.

They also point to the problem of "supply induced demand" for services which could explain the apparent increase in admissions found in some studies of intensive case management (e.g. community matrons).

Apart from a few exceptions, evaluations of interventions to reduce emergency admissions have been disappointing. Evaluations need to be evidence based, they need to allow for admission rates for individual patients falling of their own accord (a phenomenon known as regression to the mean) and to take account of variation due to chance. The authors suggest some guidelines for those needing to focus on this important and expensive aspect of healthcare.

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Journal Reference:

1. M. Roland, G. Abel. Reducing emergency admissions: are we on the right track? BMJ, 2012; 345 (sep18 1): e6017 DOI: 10.1136/bmj.e6017

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19 Sep, 2012

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Average 25% pay gap between men and women doctors largely 'inexplicable'

ScienceDaily (Sep. 18, 2012) — According to the latest survey of UK hourly pay by the Office of National Statistics (ONS), female doctors' pay lags behind their male colleagues by 28.6%.

This "eye opener" pay gap, which trends suggest has stood at around 25% on average since 2000, remains largely inexplicable, says John Appleby, Chief Economist at the King's Fund, in an article published on bmj.com today.

He explores possible reasons for this persistent gender divide in medicine and suggests that doctors have some way to catch up with other health care jobs.

For example, nursing auxiliaries and assistants show the smallest bias in pay towards men, writes Appleby, with women's median hourly pay being 0.1% less than men's. For nurses the pay gap widens to 1.9%.

Female paramedics' and health service managers pay also lags behind their male colleagues by 4.9% and 5.8% respectively, while at 16%, the pay gap for pharmacists is nearly treble this.

Interestingly, female medical radiographers appear to earn 5.3% more than their male counterparts on average, adds Appleby.

But what explains the big gap in medical practitioners' pay between men and women?

A 2009 study for the BMA suggested that some of the difference may be legitimate' and explained by factors such as experience, grade and administrative duties "although why men end up with more experience or on higher grades -- and hence more pay -- begs some questions," he writes.

Nevertheless, a significant part of the pay gap appeared to be 'unexplained' by such factors. The analysis suggested that female doctors were disadvantaged due to caring roles, a 'hostile culture' and geographical limitations which reduced their ability to change jobs (a key way to increase pay).

"These are of course problems faced by women in other occupations too. But it may be that these factors are more acute for female medical practitioners, suggests Appleby.

"Maybe there are lessons to be learned from some other health care professions, where gender pay differences are closer to zero," he concludes.

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1. J. Appleby. Is there equal pay in healthcare? Not if you are a doctor. BMJ, 2012; 345 (sep18 1): e6191 DOI: 10.1136/bmj.e6191

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19 Sep, 2012

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Blood pressure diet works, but adherence drops among African-Americans

ScienceDaily (Sep. 19, 2012) — Better adherence to the DASH (Dietary Approaches to Stop Hypertension) diet is associated with significant reductions in blood pressure. However, African-Americans may be less likely than whites to adopt the diet, according to researchers at Duke University Medical Center.

The findings, which appear online Sept. 19 in the Journal of the Academy of Nutrition and Dietetics, suggest that altering traditional recipes to meet nutritional guidelines rather than eliminating certain foods altogether may result in better adherence among African-Americans.

The DASH diet is recognized as the diet of choice for preventing and managing high blood pressure. The diet is rich in fruits, vegetables, and low fat dairy products, and is low in fats and cholesterol.

"Previous research, including results from our ENCORE study, established the DASH diet as an important approach for lowering blood pressure, and for some individuals, it may be an effective alternative to taking medication for hypertension," said James A. Blumenthal, PhD, professor of behavioral medicine in the Department of Psychiatry and Behavioral Science at Duke University Medical Center. "In this study we were interested in whether dietary adherence was related to blood pressure changes and what factors predicted who would adhere to the diet."

The study was a new analysis of data from the ENCORE trial, led by Duke researchers to evaluate the effectiveness of the DASH diet on cardiovascular health. Participants were 144 sedentary, overweight or obese adults, who had high blood pressure and were not taking medication.

Researchers measured a series of clinical and behavioral factors at the start of the study including blood pressure, weight, and physical fitness, as well as dietary habits. Depression, anxiety and social support were also evaluated as potential predictors of adherence to the regimen.

Participants were randomly assigned to one of three treatment groups: the DASH diet alone; the DASH diet in combination with weight-loss counseling and aerobic exercise; or no change in diet and exercise habits.

After four months, participants in the group that got the DASH diet plus weight-loss counseling and exercise lost an average of 19 pounds, while weight remained stable in the other two groups.

Participants in both the DASH diet alone and DASH diet plus counseling groups had significant reductions in blood pressure, with greater adherence to the DASH diet resulting in the largest drops in blood pressure. The finding suggests that that following the DASH diet lowers blood pressure, independent of exercise and weight loss.

However, the addition of weight loss and exercise to the DASH diet promoted even greater reductions in blood pressure and improved other measures of cardiovascular health. "For overweight or obese patients with high blood pressure, clinicians should recommend the DASH diet in conjunction with exercise and weight loss for the best results," said Alan Hinderliter, MD, a cardiologist at the University of North Carolina at Chapel Hill and an investigator in this study.

The researchers noted that African-American participants were less likely than white participants to eat foods recommended in the DASH diet prior to beginning the study. While both African-American and white participants in the DASH treatment groups increased the amount of DASH foods they ate, African-Americans were less likely to adopt the DASH diet compared to their white counterparts. No other demographic, behavioral, or social variable predicted whether participants would adhere to the DASH diet.

"We need to be aware of cultural differences in dietary preferences in order to help people better adopt a DASH-friendly diet," Blumenthal said. "It is important to take into account traditional food choices and cooking practices when attempting to incorporate more DASH foods into daily meal plans."

Culturally sensitive changes to implementing the DASH diet, such as modifying traditional "soul food" recipes to meet nutritional recommendations rather than eliminating foods altogether, may result in better adherence among African-Americans.

"Given the success of the DASH diet, we know that changing lifestyles can make a significant difference in people's health," Blumenthal said. "And in the long run, if people are able to maintain changes to their diet and exercise habits, it can lead to a lower risk for heart attack and stroke."

In addition to Blumenthal, Duke researchers include Dawn Epstein, Andrew Sherwood, Patrick J. Smith, Carla Caccia, Pao-Hwa Lin, Michael A. Babyak, and Julie J. Johnson. Other researchers include Linda Craighead of Emory University, and Alan Hinderliter of the University of North Carolina at Chapel Hill.

The study was funded with grants from the National Heart, Lung, and Blood Institute (HL074103), and the General Clinical Research Center, National Institutes of Health (M01-RR-30).

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19 Sep, 2012

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Evolutionary history of lizards and snakes reconstructed using massive molecular dataset

ScienceDaily (Sep. 18, 2012) — A new study, published online in Biology Letters on Sept. 19, has utilized a massive molecular dataset to reconstruct the evolutionary history of lizards and snakes. The results reveal a surprising finding about the evolution of snakes: that most snakes we see living on the surface today arose from ancestors that lived underground.

The article, entitled "Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species," describes research led by John J. Wiens, an Associate Professor in the Department of Ecology and Evolution at Stony Brook University. The study was based on 44 genes and 161 species of lizards and snakes, one of the largest genetic datasets assembled for reptiles.

The results show that almost all groups of snakes arose from within a bizarre group of burrowing blind snakes called scolecophidians. This finding implies that snakes ancestrally lived underground, and that the thousands of snake species living today on the surface evolved from these subterranean ancestors.

The authors suggest that there are still traces of this subterranean ancestry in the anatomy of surface-dwelling snakes. "For example, no matter where they live, snakes have an elongate body and a relatively short tail, and outside of snakes, this body shape is only found in lizards that live underground," said Professor Wiens. "Snakes have kept this same basic body shape as they have evolved to invade nearly every habitat on the planet -- from rainforest canopies to deserts and even the oceans."

Co-authors of the study include Carl R. Hutter, Daniel G. Mulcahy, Brice P. Noonan, Ted M. Townsend, Jack W. Sites Jr., and Tod W. Reeder. The work was performed at Stony Brook University, Brigham Young University, and San Diego State University.

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1. J. J. Wiens, C. R. Hutter, D. G. Mulcahy, B. P. Noonan, T. M. Townsend, J. W. Sites, T. W. Reeder. Resolving the phylogeny of lizards and snakes (Squamata) with extensive sampling of genes and species. Biology Letters, 2012; DOI: 10.1098/rsbl.2012.0703

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19 Sep, 2012

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The cost of glaucoma care: Small group of patients accounts for large part of costs

ScienceDaily (Sep. 18, 2012) — A small subset of patients with open-angle glaucoma (OAG) account for a large proportion of all glaucoma-related charges in the United States, according to new data published by researchers at the University of Michigan Kellogg Eye Center and Washington University, St. Louis.

These findings have importance for future evaluations of the cost-effectiveness of screening and treatment for glaucoma.

"We've identified risk factors associated with patients who are the costliest recipients of glaucoma-related eye care," says Joshua D. Stein, M.D., M.S., glaucoma specialist at Kellogg. "Among these factors are younger age, living in the northeastern United States, undergoing cataract surgery, and having other eye conditions. Understanding the characteristics of these individuals and finding ways to reduce disease burden and costs associated with their care can result in substantial cost savings."

The study, published in the September 2012 issue of the American Journal of Ophthalmology, reviewed claims data from 19,927 patients with newly diagnosed OAG who were enrolled in a large U.S. managed care network.

The researchers identified glaucoma-related charges for all such patients from 2001 through 2009. They found that the costliest 5 percent of enrollees were responsible for $10,202,871, or 24 percent, of all glaucoma-related charges. They also found that glaucoma patients generally consume the greatest relative share of resources during their first six months of care after diagnosis.

"Although there have been several studies examining the cost of caring for patients with glaucoma, most have been based on individuals who have already been diagnosed, and few have examined changes in cost of care over time," says Stein. "In this investigation, we examined two questions: What is the pattern of resource use for patients with OAG during the first seven years after disease onset, and what are the characteristics of those patients who have the greatest glaucoma-related resource use."

A chronic, progressive, incurable disease that affects more than 2 million individuals in the United States and many more worldwide, OAG is the most common cause of blindness among African Americans. OAG is the most common form of glaucoma in the United States. Caring for patients with OAG in the United States carries a total societal cost estimated at nearly $1 billion annually.

"Developing an understanding of the resource use of people with glaucoma and identifying those expected to have the largest resource use is important in a resource-constrained health care environment," says Stein. "Further, by collecting longitudinal information on resource use we can better quantify the value of slowing glaucoma progression through various interventions."

Stein is a member of U-M's Institute for Healthcare Policy and Innovation, which brings together hundreds of U-M researchers who study and test ways to improve patient care.

Citation: Longitudinal Trends in Resource Use in an Incident Cohort of Open-Angle Glaucoma Patients: Resource Use in Open-Angle Glaucoma. American Journal of Ophthalmology, September, 2012.

Authors: Joshua D. Stein, M.D., M.S.; Leslie M. Niziol, M.S.; David C. Musch, Ph.D., M.P.H; Paul P. Lee, M.D., J.D.; Sameer V. Kotak, M.S.; Colleen M. Peters, M.A.; Steven M. Kymes, Ph.D.

For more information about glaucoma care and research at the Kellogg Eye Center, visit http://kellogg.umich.edu/patientcare/glaucoma.service.html

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1. Joshua D. Stein, Leslie M. Niziol, David C. Musch, Paul P. Lee, Sameer V. Kotak, Colleen M. Peters, Steven M. Kymes. Longitudinal Trends in Resource Use in an Incident Cohort of Open-Angle Glaucoma Patients: Resource Use in Open-Angle Glaucoma. American Journal of Ophthalmology, 2012; 154 (3): 452 DOI: 10.1016/j.ajo.2012.03.032

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19 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/DVkblisX8Zw/120918184758.htm
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Compound found in purple corn may aid in developing future treatments for type 2 diabetes, kidney disease

ScienceDaily (Sep. 18, 2012) — Diabetic nephropathy is one of the most serious complications related to diabetes, often leading to end-stage kidney disease. Purple corn grown in Peru and Chile is a relative of blue corn, which is readily available in the U.S. The maize is rich in anthocyanins (also known as flavonoids), which are reported to have anti-diabetic properties.

Scientists from the Department of Food and Nutrition and Department of Biochemistry at Hallym University in Korea investigated the cellular and molecular activity of purple corn anthocyanins (PCA) to determine whether and how it affects the development of diabetic nephropathy (DN). Their findings suggest that PCA inhibits multiple pathways involved in the development of DN, which may help in developing therapies aimed at type 2 diabetes and kidney disease.

The study is entitled "Purple corn anthocyanins inhibit diabetes-associated glomerular monocyte activation and macrophage infiltration." It appears in the online edition of the American Journal of Physiology -- Renal Physiology, published by the American Physiological Society.

Methodology

Researcher Min-Kyung Kang and colleagues performed a two-part study, an in vitro experiment investigating the effects of PCA on human endothelial cells cultured under hyperglycemic kidney conditions and an in vivo study that investigated the effects of PCA on kidney tissue in diabetic mice. In the in vitro experiment, cultured cells were exposed to 1-20 µg/ml of PCA for six hours (control cells were not exposed), then assessed for level of monocyte-endothelial cell adhesion, a major factor in the development of diabetic glomerulosclerosis. In the in vivo experiment, diabetic and control mice were dosed with PCA for eight weeks, then changes in kidney tissue were assessed and immunohistological analyses were performed. Kidney tissue was further analyzed for levels of inflammatory chemokines, which are key components in DN.

Results

Researchers found that in human endothelial cells cultured in hyperglycemic kidney conditions, induction of endothelial cell adhesion molecules decreased in a dose-dependent manner with PCA exposure, meaning that the PCA likely interfered with cell-cell adhesion in glomeruli. PCA also appeared to interfere with leukocyte recruitment and adhesion to glomerular endothelial cells. In diabetic mice, PCA exposure slowed mesangial expansion and interrupted the cellular signaling pathway that may instigate glomerular adhesion and infiltration of inflammatory cells responsible for diabetic glomerulosclerosis. Finally, PCA inhibited levels of macrophage inflammatory protein-2 and monocyte chemotactic protein-1 in kidney tissue, demonstrating that it may inhibit macrophage infiltration, which is closely related to renal inflammation.

Importance of the Findings

The research suggests that anthocyanins may be the main biofunctional compound in purple corn and could protect against mesangial activation of monocytes and infiltration of macrophages in glomeruli -- the two major contributors to DN. The research further suggests that renoprotection by PCA against mesangial activation may be specific therapies targeting diabetes-associated diabetic glomerulosclerosis and renal inflammation. Finally, PCA supplementation may be an important strategy in preventing renal vascular disease in type 2 diabetes.

"PCA may be a potential renoprotective agent treating diabetes-associated glomerulosclerosis," wrote the researchers.

Research Team

In addition to Min-Kyung Kang, the study team included Jing Li, Ju-Hyun Gong, Su-Nam Kwak, Jung Han Yoon Park, Soon Sung Lim and Young-Hee Kang, all also of the Department of Food and Nutrition at Hallym University in Korea, and Jae-Yong Lee, of the Department of Biochemistry at Hallym University.

Funding

This study was funded by a grant from the Ministry of Food, Agriculture, Forestry and Fisheries through Korea Institute of Planning and Evaluation for Technology of Food, Agriculture, Forestry and Fisheries; and by the National Research Foundation of Korea.

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The above story is reprinted from materials provided by American Physiological Society (APS).

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Journal Reference:

1. M.-K. Kang, J. Li, J.-L. Kim, J.-H. Gong, S.-N. Kwak, J. H. Y. Park, J.-Y. Lee, S. S. Lim, Y.-H. Kang. Purple corn anthocyanins inhibit diabetes-associated glomerular monocyte activation and macrophage infiltration. AJP: Renal Physiology, 2012; DOI: 10.1152/ajprenal.00106.2012

Note: If no author is given, the source is cited instead.

Disclaimer: This article is not intended to provide medical advice, diagnosis or treatment. Views expressed here do not necessarily reflect those of ScienceDaily or its staff.

19 Sep, 2012

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Source: http://feeds.sciencedaily.com/~r/sciencedaily/~3/Yp-PtOFU4gs/120918184756.htm
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