Friday, April 29, 2011

Early warning system for Alzheimer's disease

 Scientists at the University of Strathclyde in Glasgow are developing a technique based on a new discovery which could pave the way towards detecting Alzheimer's disease in its earliest stages - and could help to develop urgently-needed treatments.

The technique uses the ratio of detected fluorescence signals to indicate that clusters of peptide associated with the disease are beginning to gather and to have an impact on the brain.

Current techniques are not able to see the peptide joining together until more advanced stages but a research paper from Strathclyde describes an approach which could not only give indications of the condition far sooner than is currently possible but could also screen patients without the need for needles or wires.

, the most common form of , currently affects around 450,000 people in the UK alone and currently has no cure.

Dr Olaf Rolinski, of the University of Strathclyde's Department of Physics, led the research. He said: "Alzheimer's Disease has a devastating impact on people around the world and their families but one of the reasons it is still incurable is that little is known about how and why the peptide that contributes to the disease aggregates in its initial stages.

"When irradiated with light, the intrinsic fluorescence given off by the peptide is like a communication from a spy. We took samples of the peptide and discovered that, where they were in the type of aggregation linked to Alzheimer's, they produced fluorescence light signals which could be picked up with our technique much earlier than in more conventional experiments, such as those that use the addition of a dye .

"This approach could help us understand better the role of these in the onset of Alzheimer's and discover ways in which the disease could be stopped in its tracks early on. We now want to take the research further so that it can be used in the development of drugs to treat Alzheimer's."

More information: The research paper, by Dr Rolinski and colleagues Professor David Birch and research student Mariana Amaro, has been published in Physical Chemistry Chemical Physics.

Provided by University of Strathclyde

Tropical blueberries are extreme super fruits

The first analysis of the healthful antioxidant content of blueberries that grow wild in Mexico, Central and South America concludes that some of these fruits have even more healthful antioxidants than the blueberries — already renowned as "super fruits" — sold throughout the United States. These extreme super fruits could provide even more protection against heart disease, cancer and other conditions, the report suggests. It appears in ACS' Journal of Agricultural and Food Chemistry.

Edward Kennelly and colleagues note that although there are over 600 species of blueberries and blueberry-like fruits growing in Mexico, Central and South America (the so-called "neotropics"), very little research has been done on them. U.S.-grown blueberries are already famous for their antioxidants, which help the body get rid of harmful free radicals. So, the researchers decided to find out how neotropical blueberries stacked up against a grocery-store variety.

They found that two types of neotropical blueberries were extreme super fruits — they had significantly more than a type of blueberry commonly sold in U.S. supermarkets stores. The researchers say that these neotropical "have the potential to be even more highly promising edible fruits."

More information: “Edible Neotropical Blueberries: Antioxidant and Compositional Fingerprint Analysis” Journal of Agricultural and Food Chemistry.

Provided by American Chemical Society (news : web)

Water molecules characterize the structure of DNA genetic material

Water molecules surround the genetic material DNA in a very specific way. Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have discovered that, on the one hand, the texture of this hydration shell depends on the water content and, on the other hand, actually influences the structure of the genetic substance itself. These findings are not only important in understanding the biological function of DNA; they could also be used for the construction of new DNA-based materials.

The DNA's double helix never occurs in isolation; instead, its entire surface is always covered by water molecules which attach themselves with the help of hydrogen bonds. But the DNA does not bind all molecules the same way. "We've been able to verify that some of the water is bound stronger whereas other molecules are less so," notes Dr. Karim Fahmy, Head of the Biophysics Division at the Institute of Radiochemistry. This is, however, only true if the water content is low. When the water sheath swells, these differences are adjusted and all hydrogen bonds become equally strong. This, in turn, changes the geometry of the DNA strand: The backbone of the double helix, which consists of sugar and phosphate groups, bends slightly. "The precise DNA structure depends on the specific amount of water surrounding the molecule," summarizes Dr. Fahmy.

Analyses of the genetic material were conducted at the HZDR by the doctoral candidate Hassan Khesbak. The DNA, which came from salmon testes, was initially prepared in thin films and then wetted with ultrafine doses of water within a few seconds. With the help of infrared spectroscopy, Hassan Khesbak was able to verify that the strength of hydrogen bonds varies and that water molecules exhibit different rest periods in such configurations. Oscillations of the water bonds in the hydration shell of the double helix can be excited by infrared light. The higher the frequency of the oscillation, the looser the hydrogen bond. It became apparent that the sugar components and the base pairs create particularly strong bonds with the water sheath while the bonds between the water and the phosphate groups are weaker. The results were published just recently in the Journal of the American Chemical Society.

"DNA is, thus, a responsive material," explains Karim Fahmy. "By this, we refer to materials which react dynamically to varying conditions. The double helix structure, the strength of the hydrogen bonds, and even the DNA volume tend to change with higher water contents." Already today, genetic material is an extraordinarily versatile and interesting molecule for so-called DNA nanotechnology. Because with DNA it is possible to realize highly ordered structures with new optical, electronic, and mechanical properties at tiny dimensions which are also of interest for the HZDR. The bound water sheath is not just an integral part of such structures. It can also assume a precise switching function because the results indicate that increasing the hydration shell by only two water molecules per phosphate group may cause the DNA structure to "fold" instantly. Such water dependent switching processes might be able to control, for example, the release of active agents from DNA-based materials.

It does not come as a complete surprise that the water sheath of the genetic material is also of great relevance to the natural biological function of DNA. Because every biomolecule which is bound to the DNA has to first displace the water sheath. The Dresden scientists have analyzed this process for the peptide indolicidin. This antimicrobial protein is less structured and very flexible. That it still "identifies" the double helix so precisely is due to the fact that highly structured water molecules are released when it coalesces with the genetic material. The water sheath's restructuring, which is actually an energetic advantage, increases the binding of the active agent. Such details are really important for the development of DNA-binding drugs, for example, in cancer therapy because they can be ascertained with the method developed at the HZDR.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Helmholtz Association of German Research Centres, via EurekAlert!, a service of AAAS.

Journal Reference:

Hassan Khesbak, Olesya Savchuk, Satoru Tsushima, Karim Fahmy. The Role of Water H-Bond Imbalances in B-DNA Substate Transitions and Peptide Recognition Revealed by Time-Resolved FTIR Spectroscopy. Journal of the American Chemical Society, 2011; 133 (15): 5834 DOI: 10.1021/ja108863v

Fine chemical processes safer and more efficient with new type of reactor

Researcher Marco Meeuwse of Eindhoven University of Technology (TU/e) has developed a unique chemical reactor, the 'spinning disc reactor'. This is a cylinder containing a rotor that increases the safety and efficiency of chemical production processes involving gases, liquids and solids through its very high mass transfer rate. This new reactor is particularly beneficial for the pharmaceutical and fine chemical industries.

The idea of the 'spinning disc reactor' came from Meeuwse's co-supervisor John van der Schaaf. Around five years ago he had seen a research project in which a liquid was sprayed onto a rotating disc and driven outwards by centrifugal force.

Assistant professor Van der Schaaf thought that combining the rotating disc with a nearby wall would create high shear stress and rapid turbulence, leading to high efficiency. He asked doctoral candidate Meeuwse to investigate whether this was true. Now, four years later, he can say without hesitation that the newly developed reactor does exactly what was expected of it. "In fact it does even more," says Meeuwse. "We were sure it would perform better than the conventional reactors, but we didn't expect it to be so much better."

Gas is fed into the reactor through the floor of the cylinder, with the rotating disc located just above it. The gas bubbles are effectively sheared off by the high-speed flow of rotating liquid through which they pass. "The higher the rotational speed, the smaller the bubbles and the larger the surface area," explains Meeuwse. "That translates into a higher rate of reaction and mass transfer. That was confirmed every time by analyses of the images of the gas-liquid flow and the mass transfer measurements."

Meeuwse was able to scale-up the principle by using a series of rotating discs. Three discs with a diameter of 13 cm were mounted on a shared spindle in a cylinder. "If each unit does the same thing, the total mass transfer of the three discs in series should also be three times as great. Our measurements clearly showed that this reasoning was true, providing the proof that we can scale the system up." An extra benefit of the reactor is that it is safer, because it is much smaller than conventional reactors. This is a big advantage in processes using hazardous substances.

Further development of the reactor is currently in full swing, and a number of related PhD projects are in progress at TU/e. A major equipment manufacturer has become involved, and several chemical and pharmaceutical companies have also shown interest, Meeuwse explains. "We know that this reactor is better than the conventional types. We have measured improvements by factors ranging from two to ten, but we haven't yet been able to identify the full potential of the new concept."

Is there a big market for this new type of reactor? "It is definitely usable for processes in which conversion and selectivity are important factors, such as in the pharmaceutical industry," says Meeuwse. "The raw materials for medicines are very costly, so the less you need to purify the products afterwards, and the less waste you throw away, the more rewarding it will be to use our reactor. In terms of volume it may not be a big market, but on the other hand the processes concerned have a high added value."

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by Eindhoven University of Technology, via AlphaGalileo.

Diamond light illuminates process of silver decay in Catalonian altarpieces


Scientists from the Technical University of Catalonia in Barcelona have teamed up with Diamond Light Source to use a brilliant infrared microbeam to understand at the microscopic scale molecular processes affecting the decay or preservation of polychrome carved wood adorning churches and altarpieces depicting saints.

Celebrated on 23rd April each year, St George is not only the patron saint of England, but also the autonomous region of Catalonia and many other countries. His image, and those of other saints, adorns a number of medieval altarpieces in Catalonia around Europe. But many of these sacred artifacts are badly damaged due to the corrosive effects of air on organic-based glues or varnish that hold or cover the thin silver or gold foils used for the Saints’ aureola – the radiant cloud that surrounds the depicted sacred person.

The results of the group’s work published in the journal Analytical and Bioanalytical Chemistry demonstrate that, under different atmospheric conditions, various geographic areas and different climates, the microscopic alteration compounds formed on precious metal lustres are due to atmospheric corrosion but mainly depend on the state of conservation of the organic protective coating.

Dr. Nati Salvado, from the Technical University of Catalonia and lead researcher on the project, explains: “The conservation state of the silver foil is found to be directly related to the silver-atmosphere contact extent. When protected by a paint layer or a well-preserved resin coating, the silver foil can be found in a good conservation state. On the contrary, if the protective layer appears partly or fully absent leaving the silver surface, either directly or through the cracks, exposed to the atmosphere, the silver alteration products are all that is left.” 

Microscopic samples of silver decorations from various 15th Century artworks in different states of conservation were examined at Diamond.  These include the valuable altarpieces of St George, St Lucia, St Joan and others, some on display in major collections such as the Museu Nacional d’art de Catalunya in Barcelona.

Dr. Salvado said: “We are studying different artworks from the period of the old Crown of Aragon in order to determine the similarities and differences in the painting technique between painters and their relations with other painters in Europe. It is a very interesting historical period because it corresponds to the transition from Gothic to Renaissance style and technique. The artworks were preserved in various geographic areas with different climates, and the corrosion products enable us to assess the effect of the environmental conditions on the corrosion of foils.”

More information: ‘SR-XRD and SR-FTIR study of the alteration of silver foils in medieval paintings.' Nati Salvadó, et al. Analytical and Bioanalytical Chemistry, Volume 399, Number 9, 3041-3052. … 6-010-4365-5

Provided by Diamond Light Source

Get a whiff of this: Low-cost sensor can diagnose bacterial infections

Bacterial infections really stink. And that could be the key to a fast diagnosis.

Researchers have demonstrated a quick, simple method to identify by smell using a low-cost array of printed pigments as a . Led by University of Illinois chemistry professor Ken Suslick, the team published its results in the .

Hospitals have used blood cultures as the standard for identifying blood-borne bacterial infections for more than a century. While there have been some improvements in automating the process, the overall method has remained largely constant. Blood samples are incubated in vials for 24 to 48 hours, when a carbon dioxide sensor in the vials will signal the presence of bacteria. But after a culture is positive, doctors still need to identify which species and strain of bacteria is in the vial, a process that takes up to another day.

"The major problem with the clinical blood culturing is that it takes too long," said Suslick, the Marvin T. Schmidt professor of chemistry, who also is a professor of materials science and engineering and a member of the Beckman Institute for Advanced Science and Technology. "In 72 hours they may have diagnosed the problem, but the patient may already have died of sepsis."

While there has been some interest in using sophisticated spectroscopy or genetic methods for clinical diagnosis, Suslick's group focused on another distinctive characteristic: smell. Many experienced can identify bacteria based on their aroma. Bacteria emit a complex mixture of chemicals as by-products of their metabolism. Each species of bacteria produces its own unique blend of gases, and even differing strains of the same species will have an aromatic "fingerprint."

An expert in chemical sensing, Suslick previously developed an artificial "nose" that can detect and identify poisonous gases, toxins and explosives in the air.

"Our approach to this problem has been to think of bacteria as simply micron-sized chemical factories whose exhaust is not regulated by the EPA," Suslick said. "Our technology is now well-proven for detecting and distinguishing among different chemical odorants, so applying it to bacteria was not much of a stretch."

An array developed by University of Illinois researchers demonstrated on 10 common infectious bacteria. The color changes of the sensor array show what kind of bacteria is growing and even if they are antibiotic resistant. Credit: K. S. Suslick

The is an array of 36 cross-reactive pigment dots that change color when they sense chemicals in the air. The researchers spread blood samples on Petri dishes of a standard growth gel, attached an array to the inside of the lid of each dish, then inverted the dishes onto an ordinary flatbed scanner. Every 30 minutes, they scanned the arrays and recorded the color changes in each dot. The pattern of color change over time is unique to each bacterium.

"The progression of the pattern change is part of the diagnosis of which bacteria it is," Suslick said. "It's like time-lapse photography. You're not looking just at a single frame, you're looking at the motion of the frames over time."

In only a few hours, the array not only confirms the presence of bacteria, but identifies a specific species and strain. It even can recognize antibiotic resistance – a key factor in treatment decisions.

In the paper, the researchers showed that they could identify 10 of the most common disease-causing bacteria, including the hard-to-kill hospital infection methicillin-resistant Staphylococcus aureus (MRSA), with 98.8 percent accuracy. However, Suslick believes the array could be used to diagnose a much wider variety of infections.

"We don't have an upper limit. We haven't yet found any bacteria that we can't detect and distinguish from other bacteria," he said. "We picked out a sampling of human pathogenic as a starting point."

Given their broad sensitivity, the chemical-sensing arrays also could enable breath diagnosis for a number of conditions. Medical researchers at other institutions have already performed studies using Suslick's arrays to diagnose sinus infections and to screen for lung cancer.

Next, the team is working on integrating the arrays with vials of liquid growth medium, which is a faster culturing agent and more common in clinical practice than Petri dishes. They have also improved the pigments to be more stable, more sensitive and easier to print. The device company iSense, which Suslick co-founded, is commercializing the array technology for clinical use.

More information: "Rapid Identification of Bacteria with a Disposable Colorimetric Sensing Array," http://pubs.acs.or … 21/ja201634d

Rapid identification of both species and even specific strains of human pathogenic bacteria grown on standard agar has been achieved from the volatiles they produce using a disposable colorimetric sensor array in a Petri dish imaged with an inexpensive scanner. All 10 strains of bacteria tested, including Enterococcus faecalis and Staphylococcus aureus and their antibiotic-resistant forms, were identified with 98.8% accuracy within 10 h, a clinically important time frame. Furthermore, the colorimetric sensor arrays also proved useful as a simple research tool for the study of bacterial metabolism and as an easy method for the optimization of bacterial production of fine chemicals or other fermentation processes.

Provided by University of Illinois at Urbana-Champaign (news : web)

Researchers find fat turns into soap in sewers, contributes to overflows

Researchers from North Carolina State University have discovered how fat, oil and grease (FOG) can create hardened deposits in sewer lines: it turns into soap! The hardened deposits, which can look like stalactites, contribute to sewer overflows.

"We found that FOG deposits in sewage collection systems are created by that turn the from FOG into, basically, a huge lump of soap," says Dr. Joel Ducoste, a professor of civil, construction and environmental engineering at NC State and co-author of a paper describing the research. Collection systems are the pipes and pumping stations that carry wastewater from homes and businesses to sewage-treatment facilities.

These hardened FOG deposits reduce the flow of wastewater in the pipes, contributing to – which can cause environmental and public-health problems and lead to costly fines and repairs.

The research team used a technique called Fourier Transform Infrared (FTIR) spectroscopy to determine what the FOG deposits were made of at the molecular level. FTIR spectroscopy shoots a sample material with infrared light at various wavelengths. Different molecular bonds vibrate in response to different wavelengths. By measuring which infrared wavelengths created vibrations in their FOG samples, researchers were able to determine each sample's molecular composition.

Using this technique, researchers confirmed that the hardened deposits were made of calcium-based fatty acid salts – or .

"FOG itself cannot create these deposits," Ducoste says. "The FOG must first be broken down into its constituent parts: glycerol and free fatty acids. These free fatty acids – specifically, saturated fatty acids – can react with calcium in the sewage collection system to form the hardened deposits.

"Until this point we did not know how these deposits were forming — it was just a hypothesis," Ducoste says. "Now we know what's going on with these really hard deposits."

The researchers are now focused on determining where the calcium in the collection system is coming from, and how quickly these deposits actually form. Once they've resolved those questions, Ducoste says, they will be able to create numerical models to predict where a sewage system may have "hot spots" that are particularly susceptible to these blockages.

Ultimately, Ducoste says, "if we know how – and how quickly – these deposits form, it may provide scientific data to support policy decisions related to preventing sewer overflows."

More information: “Evidence for Fat, Oil, and Grease (FOG) Deposit Formation Mechanisms in Sewer Lines”
Authors: Xia He, Mahbuba Iasmin, Lisa O. Dean, Simon E. Lappi, Joel J. Ducoste, and Francis L. de los Reyes, III, North Carolina State University
Published: forthcoming, Environmental Science & Technology

The presence of hardened and insoluble fats, oil, and grease (FOG) deposits in sewer lines is a major cause of line blockages leading to sanitary sewer overflows (SSOs). Despite the central role that FOG deposits play in SSOs, little is known about the mechanisms of FOG deposit formation in sanitary sewers. In this study, FOG deposits were formed under laboratory conditions from the reaction between free fatty acids and calcium chloride. The calcium and fatty acid profile analysis showed that the laboratory-produced FOG deposit displayed similar characteristics to FOG deposits collected from sanitary sewer lines. Results of FTIR analysis showed that the FOG deposits are metallic salts of fatty acid as revealed by comparisons with FOG deposits collected from sewer lines and pure calcium soaps. Based on the data, we propose that the formation of FOG deposits occurs from the aggregation of excess calcium compressing the double layer of free fatty acid micelles and a saponification reaction between aggregated calcium and free fatty acids.

Provided by North Carolina State University (news : web)