Sunday, January 15, 2012

Some 'low-gluten' beer contains high levels of gluten

Michelle Colgrave and colleagues explain that (CD) affects more than 2 million people worldwide. Gluten, a protein found in foods and beverages made from barley, wheat and rye triggers a reaction in CD patients that affects the small intestine, blocking the absorption of from food. Symptoms vary, but often include diarrhea or constipation, fatigue and abdominal pain. The cause is unknown, and there is no cure. The only treatment is to stay on a life-long gluten-free diet. Barley is used to make beer, but whether the finished product contains gluten is controversial, with some beer companies contending that the brewing process gets rid of gluten or reduces it to very low levels. Existing tests for detecting gluten in malted products are not very accurate. So the scientists developed a highly accurate new test for hordein, the gluten component in barley-based beers.

As expected, their analysis of 60 commercial beers found that eight labeled "gluten-free" did not contain gluten. But many regular, commercial beers had significant levels of gluten. Most surprising, two beers labeled as "low-gluten" had about as much gluten as regular beer.

More information:
What is in a Beer? Proteomic Characterization and Relative Quantification of Hordein (Gluten) in Beer, J. Proteome Res., Article ASAP DOI: 10.1021/pr2008434

The suite of prolamin proteins present in barley flour was characterized in this study, in which we provide spectral evidence for 3 previously characterized prolamins, 8 prolamins with only transcript evidence, and 19 genome-derived predicted prolamins. An additional 9 prolamins were identified by searching the complete spectral set against an unannotated translated EST database. Analyses of wort, the liquid extracted from the mashing process during beer production, and beer were undertaken and a similar suite of prolamins were identified. We have demonstrated by using tandem mass spectrometry that hordeins are indeed present in beer despite speculation to the contrary. Multiple reaction monitoring (MRM) mass spectrometry was used for the rapid analyses of hordein in barley (Hordeum vulgare L.) beer. A selection of international beers were analyzed and compared to the results obtained with hordein deletion beers. The hordein deletion beers were brewed from grains carrying mutations that prevented the accumulation of either B-hordeins (Riso 56) or C-hordeins (Riso 1508). No intact C-hordeins were detected in beer, although fragments of C-hordeins were present in wort. Multiple reaction monitoring analysis of non-barley based gluten (hordein)-free beers targeting the major hordein protein families was performed and confirmed the absence of hordein in several gluten-free commercial beers.

Provided by American Chemical Society (news : web)

Researchers identify lipid profile characteristic of newly diagnosed type 1 diabetes

The Editors-in-Chief of Clinical Biochemistry and Clinica Chimica Acta selected the paper for the distinction and included it in a booklet distributed at international meetings sponsored by the International Federation of Clinical Chemistry.

T1DM affects more than 1 million individuals in the United States alone. Currently, the best approach for predicting those at risk for developing T1DM before symptoms appear is by measuring to islet cell antigens in the pancreas.
Lipids 101
Lipids are one of the four major molecular components of , along with proteins, sugars, and . They store energy, make up the structures of cells, and participate in cell signaling.  The "lipidome" refers to all lipids in cells and "lipidomics" to the measurement thereof. Autoantibodies cause many autoimmune diseases. Multiple autoantibody positives and their persistence are unequivocally related to the risk of progression to T1DM. However, autoantibodies are difficult to measure with consistent sensitivity and specificity, and assay performance varies considerably among laboratories. Sound methods are needed to identify new biomarkers that predict T1DM development and can also be transferred to other laboratories.

To improve and standardize measurement of autoantibodies associated with T1DM and identify novel protein , the Centers for Disease Control and Prevention (CDC) and the Immunology of Diabetes Society created the Diabetes Antibody Standardization Program (DASP). Scientists at PNNL and the CDC previously conducted a global proteomics analysis of plasma and serum samples from the DASP and identified five candidates in a sample subset (Metz et al. 2008).

The role of ZAG: Scientists found that one protein in particular, zinc alpha-2-glycoprotein (ZAG), was strongly upregulated, or increased, in individuals with T1DM. ZAG, a member of the immunoglobulin superfamily, is responsible for lipid mobilization. This means that increased levels of ZAG in patients may indicate a system-wide mobilization of lipids for energy production, particularly because these individuals lack endogenous insulin and cannot rely on blood glucose (sugar) for their energy needs. The scientists hypothesized that perturbations, or changes, may be present in the blood lipidome of individuals with newly diagnosed T1DM.

To test their hypothesis, they performed lipidomics analyses on the same DASP samples to identify perturbations in the lipids of individuals with recently diagnosed T1DM and to potentially identify a lipid profile that could predict or diagnose the disease.

"When discussing lipids in the context of personal health, most people think of total cholesterol, HDL, LDL, and triglycerides, which are the lipids typically measured in a blood lipid panel at clinics and hospitals," said PNNL chemist Dr. Thomas Metz. "They don't realize that there is a broad diversity of lipids in blood and tissues—thousands of individual lipid molecular species comprising about a dozen or so major classes.

"For example, HDL and LDL themselves are comprised of hundreds of molecular species of cholesterol esters and triglycerides. So, while the typical clinic blood lipid panel may not indicate differences in total cholesterol, HDL, LDL, and triglycerides, there may be dramatic changes at the level of lipid molecular species. These are the changes that only mass spectrometry can identify with sufficient sensitivity and throughput."

The scientists used capillary liquid chromatography (LC) coupled with Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) and the accurate mass and time (AMT) tag approach developed at PNNL to identify and quantify lipids present in healthy and diabetic individuals. The AMT tag approach relies on initial, low-throughput shotgun LC-MS/MS analyses to populate a database of identified molecules followed by higher throughput and more quantitative LC-MS analyses.

They identified more than 559 lipids that were significantly different (q < 0.05) between control and patient samples, of which 55 were structurally identified by matching to entries in a blood plasma lipid AMT tag database. These lipids may represent a profile characteristic of newly diagnosed T1DM.

"The patients in our study had well-controlled blood glucose levels, so their blood lipid panels showed no differences in total cholesterol, HDL, LDL, and triglycerides compared to the controls," Metz said. "In that respect, it is very exciting that we identified so many molecular species that showed statistically significant differences between the patients and controls. It really highlights an area worth further study in the context of T1DM."

More information: Sorensen CM, J Ding, Q Zhang, T Alquier, R Zhao, PW Mueller, RD Smith, and TO Metz. 2010. "Perturbations in the lipid profile of individuals with newly diagnosed type 1 diabetes mellitus: lipidomics analysis of a Diabetes Antibody Standardization Program sample subset." Clinical Biochemistry 43(12):948-956.

Metz TO, W-J Qian, JM Jacobs, MA Gritsenko, RJ Moore, AD Polpitiya, ME Monroe, DG Camp II, PW Mueller, and RD Smith. 2008. "Application of Proteomics in the Discovery of Candidate Protein Biomarkers in a Diabetes Autoantibody Standardization Program Sample Subset." Journal of Proteome Research 7(2):698-707.

Provided by Pacific Northwest National Laboratory (news : web)

Proteins in focus: Adjustable protein microlenses made by femtosecond laser direct writing

Proteins are potentially useful as “building materials” for microcomponents because they are readily available, inexpensive, and biocompatible. They can also change their properties in response to external stimuli, which makes them an interesting material for use in adjustable microlenses. However, lenses must be extremely precise in order to meet optical requirements—something difficult to achieve with proteins. In addition, they must be fast, simple, and inexpensive to produce.

The Chinese researchers have now met this challenge: They used a to “write” the desired micrometer-sized lens shape out of a solution of bovine serum albumin, a . Methylene blue acts as a photosensitizer, which captures the light energy like an antenna and triggers a crosslinking reaction of the protein molecules. Driven by a computer, the laser cuts out the desired three-dimensional form voxel by voxel. A voxel is a three-dimensional pixel, a tiny segment of volume. The irradiation used is in femtosecond pulses, which lasts on the order of 10-13 seconds. The crosslinking reaction only takes place in the locations that are irradiated. After the reaction, the protein molecules that have not reacted can simply be rinsed away. What stays behind is a cross-linked, aqueous protein gel in the shapes of micrometer-sized lenses.

Direct writing with lasers usually results in structures that have too rough a surface for optical applications. By optimizing the duration of the laser pulse, the pulse intensity, and the protein concentration, Sun and his team obtained lenses with outstanding optical properties.

The special trick in this case is that the amount of liquid absorbed by the protein gel depends on the pH value of the solution. Increasing the pH causes the lens to swell. If the increase in thickness is limited by a glass surface, the lens primarily grows in width and becomes flatter. If the pH value is reduced, the gel shrinks and the lens is more curved. Because the radius of curvature determines the focal length of the lens, this method can be used to focus the microlenses.

Because the protein lenses are biocompatible, they may be used in optical analytical systems for medical diagnostics or lab-on-a-chip technology.

More information: Hong-Bo Sun, Dynamically Tunable Protein Microlenses, Angewandte Chemie International Edition, … ie.201105925

Provided by Wiley (news : web)

Scientists create a functional model of the extracellular matrix

The extracellular matrix (ECM) provides the physical and chemical conditions that enable the development of all . It is a complex nano-to-microscale structure made up of protein fibres and serves as a dynamic substrate that supports and regeneration.

Man-made structures designed to mimic and replace the native matrix in damaged or diseased tissues are highly sought after to advance our understanding of tissue organisation and to make regenerative medicine a reality.

Self-assembling peptide fibres that have similar properties to those of the native matrices are of particular interest. However, these near-crystalline fail to arrange themselves into interconnected meshes at the , which is critical for bringing cells together and supporting .

To solve this problem, a research team at NPL designed a small protein consisting of two complementary domains (structural units) that promote the formation of highly branched networks of fibres that span microscopic dimensions. The team showed that the created matrix is very efficient in supporting cell attachment, growth and proliferation.

Max Ryadnov, the lead researcher at NPL, said: "The extracellular matrix is a cellular "scaffolding", which provides necessary signalling environment for cell growth and development into tissues and can help to heal wounds and other damaged tissues. Therefore, extracellular mimetics such as one developed by NPL could be useful for the progress of regenerative medicine."

More information: The full research was published recently in Angewandte Chemie. It is available here:

Provided by National Physical Laboratory

Applying pressure reaps material rewards

Multiferroic materials have both ferromagnetic and ferroelectric properties that make them ideal for an improved class of memory devices. Ferromagnetic materials are essential for most electronic memory devices because they can retain long-lasting magnetic properties after exposure to a magnetic field. The electrical properties of ferroelectric materials are controllable using an electric field. The combination of these properties means that it is possible to control magnetic memories with an electrical field while reducing heat loss.  

Ishiwata and colleagues created an initial sample of YMnO3 by mixing the compounds Y2O3 and Mn2O3 at 1,300 °C. “This ambient-pressure phase of YMnO3 is a kind of multiferroic, but … its electronic properties cannot be controlled by magnetic fields,” explains Ishiwata. Moreover, the sample was polycrystalline; that is, made up of many tiny . The researchers created larger crystals (Fig. 1) by mixing this precursor with potassium chloride and water and subjecting it to a pressure almost 55,000 times that of atmospheric pressure and temperatures in excess of 1,000 °C for two hours. “The crystal growth of multiferroic YMnO3 is normally hampered by damage caused in the high-pressure cell,” explains Ishiwata. “By adding water, we drastically lowered the melting point of YMnO3 and therefore reduced the reaction time.”

To provide clear evidence of the strong magneto-electric effects, Ishiwata and colleagues investigated their sample at various temperatures and under an applied magnetic field. A change in atomic structure transformed the precursor YMnO3 into a useful multiferroic material. The precursor had a hexagonal lattice arrangement. The high pressure converted this to a type of crystal known as an orthorhombic perovskite—so named because it has a similar, but slightly tilted, to the natural mineral perovskite.

Now that they are able to reliably grow large single YMnO3 crystals, the researchers can thoroughly investigate the properties of this useful material. “It has been predicted that perovskite-type YMnO3 should have a large polarization; that is, a strong atomic-level response to electric fields,” says Ishiwata. “The observed polarization is not as large as predicted yet, but it is still the largest of any magnetic-order-driven multiferroic.”

More information: Ishiwata, S., et al. High-pressure hydrothermal crystal growth and multiferroic properties of a perovskite YMnO3. Journal of the American Chemical Society 133, 13818–13820 (2011).

Provided by RIKEN (news : web)