Accumulation of Maillard reaction products in skin collagen in diabetes and aging

To investigate the contribution of glycation and oxidation reactions to the modification of insoluble collagen in aging and diabetes, Maillard reaction products were measured in skin collagen from 39 type 1 diabetic patients and 52 nondiabetic control subjects. Compounds studied included fructoselysine (FL), the initial glycation product, and the glycoxidation products, N epsilon-(carboxymethyl) lysine (CML) and pentosidine, formed during later Maillard reactions. Collagen-linked fluorescence was also studied. In nondiabetic subjects, glycation of collagen (FL content) increased only 33% between 20 and 85 yr of age. In contrast, CML, pentosidine and fluorescence increased five-fold, correlating strongly with age. In diabetic patients, collagen FL was increased threefold compared with nondiabetic subjects, correlating strongly with glycated hemoglobin but not with age. Collagen CML, pentosidine and fluorescence were increased up to twofold in diabetic compared with control patients: this could be explained by the increase in glycation alone, without invoking increased oxidative stress. There were strong correlations among CML, pentosidine and fluorescence in both groups, providing evidence for age-dependent chemical modification of collagen via the Maillard reaction, and acceleration of this process in diabetes. These results support the description of diabetes as a disease characterized by accelerated chemical aging of long-lived tissue proteins.

Glycation and oxidation:a role in the pathogenesis of atherosclerosis

Reactions involving glycation and oxidation of proteins and lipids are believed to contribute to atherogenesis. Glycation, the nonenzymatic binding of glucose to protein molecules, can increase the atherogenic potential of certain plasma constituents, including low-density lipoprotein (LDL). Glycation of LDL is significantly increased in diabetic patients compared with normal subjects, even in the presence of good glycemic control. Metabolic abnormalities associated with glycation of LDL include diminished recognition of LDL by the classic LDL receptor; increased covalent binding of LDL in vessel walls; enhanced uptake of LDL by macrophages, thus stimulating foam cell formation; increased platelet aggregation; formation of LDL-immune complexes; and generation of oxygen free radicals, resulting in oxidative damage to both the lipid and protein components of LDL and to any nearby macromolecules. Oxidized lipoproteins are characterized by cytotoxicity, potent stimulation of foam cell formation by macrophages, and procoagulant effects. Combined glycation and oxidation, "glycoxidation," occurs when oxidative reactions affect the initial products of glycation, and results in irreversible structural alterations of proteins. Glycoxidation is of greatest significance in long-lived proteins such as collagen. In these proteins, glycoxidation products, believed to be atherogenic, accumulate with advancing age: in diabetes, their rate of accumulation is accelerated. Inhibition of glycation, oxidation, and glycoxidation may form the basis of future antiatherogenic strategies in both diabetic and nondiabetic individuals.

Lipoprotein glycation and its metabolic consequences

In people with diabetes, glycation of apolipoproteins correlates with other indices of recent glycemic control, including HbA1. For several reasons, increased glycation of apolipoproteins may play a role in the accelerated development of atherosclerosis in diabetic patients. Recognition of glycated LDL by the classical LDL receptor is impaired, whereas its uptake by human monocyte-macrophages is enhanced. These alterations may contribute to hyperlipidemia and accelerated foam-cell formation, respectively. Glycation of LDL also enhances its capacity to stimulate platelet aggregation. The uptake of VLDL from diabetic patients by human monocyte-macrophages is enhanced. This enhancement may be due, at least in part, to increased glycation of its lipoproteins. Glycation of HDL impairs its recognition by cells and reduces its effectiveness in reverse cholesterol transport. Glycation of apolipoproteins may also generate free radicals, increasing oxidative damage to the apolipoproteins themselves, the lipids in the particle core, and any neighboring macromolecules. This effect may be most significant in extravasated lipoproteins. In these, increased glycation promotes covalent binding to vascular structural proteins, and oxidative reactions may cause direct damage to the vessel wall. Glycoxidation, or browning, of sequestered lipoproteins may further enhance their atherogenicity. Finally, glycated or glycoxidized lipoproteins may be immunogenic, and lipoprotein-immune complexes are potent stimulators of foam-cell formation.

Radiobiology at ultra-high dose rates employing laser-driven ions

The potential that laser based particle accelerators offer to solve sizing and cost issues arising with conventional proton therapy has generated great interest in the understanding and development of laser ion acceleration, and in investigating the radiobiological effects induced by laser accelerated ions. Laser-driven ions are produced in bursts of ultra-short duration resulting in ultra-high dose rates, and an investigation at Queen's University Belfast was carried out to investigate this virtually unexplored regime of cell rdaiobiology. This employed the TARANIS terawatt laser producing protons in the MeV range for proton irradiation, with dose rates exceeding 10 Gys on a single exposure. A clonogenic assay was implemented to analyse the biological effect of proton irradiation on V79 cells, which, when compared to data obtained with the same cell line irradiated with conventionally accelerated protons, was found to show no significant difference. A Relative Biological effectiveness of 1.4±0.2 at 10 % Survival Fraction was estimated from a comparison with a 225 kVp X-ray source. © 2013 SPIE.

ELIMED:A new hadron therapy concept based on laser driven ion beams

Laser accelerated proton beams have been proposed to be used in different research fields. A great interest has risen for the potential replacement of conventional accelerating machines with laser-based accelerators, and in particular for the development of new concepts of more compact and cheaper hadrontherapy centers. In this context the ELIMED (ELI MEDical applications) research project has been launched by INFN-LNS and ASCR-FZU researchers within the pan-European ELI-Beamlines facility framework. The ELIMED project aims to demonstrate the potential clinical applicability of optically accelerated proton beams and to realize a laser-accelerated ion transport beamline for multi-disciplinary user applications. In this framework the eye melanoma, as for instance the uveal melanoma normally treated with 62 MeV proton beams produced by standard accelerators, will be considered as a model system to demonstrate the potential clinical use of laser-driven protons in hadrontherapy, especially because of the limited constraints in terms of proton energy and irradiation geometry for this particular tumour treatment. Several challenges, starting from laser-target interaction and beam transport development up to dosimetry and radiobiology, need to be overcome in order to reach the ELIMED final goals. A crucial role will be played by the final design and realization of a transport beamline capable to provide ion beams with proper characteristics in terms of energy spectrum and angular distribution which will allow performing dosimetric tests and biological cell irradiation. A first prototype of the transport beamline has been already designed and other transport elements are under construction in order to perform a first experimental test with the TARANIS laser system by the end of 2013. A wide international collaboration among specialists of different disciplines like Physics, Biology, Chemistry, Medicine and medical doctors coming from Europe, Japan, and the US is growing up around the ELIMED project with the aim to work on the conceptual design, technical and experimental realization of this core beamline of the ELI Beamlines facility. © 2013 SPIE.

Role of glycation in modification of lens crystallins in diabetic and nondiabetic senile cataracts

To assess the significance of glycation, nonenzymatic browning, and oxidation of lens crystallins in cataract formation in elderly diabetic patients, we measured three distinct products of glycation, browning, and oxidation reactions in cataractous lens crystallins from 29 diabetic patients (mean +/- SD age 72.8 +/- 8.8 yr) and 24 nondiabetic patients (age 73.5 +/- 8.3 yr). Compounds measured included 1) fructoselysine (FL), the first stable product of glycation; 2) pentosidine, a fluorescent, carbohydrate-derived protein cross-link between lysine and arginine residues formed during nonenzymatic browning; and 3) N epsilon-(carboxymethyl)lysine (CML), a product of autoxidation of sugar adducts to protein. In diabetic compared with nondiabetic patients, there were significant increases (P less than 0.001) in HbA1 (10.2 +/- 3.1 vs. 7.1 +/- 0.7%), FL (7.6 +/- 5.4 vs. 1.7 +/- 1.2 mmol/mol lysine), and pentosidine (6.3 +/- 2.8 vs. 3.8 +/- 1.9 mumol/mol lysine). The disproportionate elevation of FL compared with HbA1 suggests a breakdown in the lens barrier to glucose in diabetes, whereas the increase in pentosidine is indicative of accelerated nonenzymatic browning of diabetic lens crystallins. CML levels were similar in the two groups (7.1 +/- 2.4 vs. 6.8 +/- 3.0 mmol/mol lysine), providing no evidence for increased oxidative stress in the diabetic cataract. Thus, although the modification of lens crystallins by autoxidation reactions was not increased in diabetes, the increase in glycation and nonenzymatic browning suggests that these processes may acclerate the development of cataracts in diabetic patients.

The Maillard reaction in vivo

The Maillard or browning reaction between reducing sugars and protein contributes to the chemical deterioration and loss of nutritional value of proteins during food processing and storage. This article presents and discusses evidence that the Maillard reaction is also involved in the chemical aging of long-lived proteins in human tissues. While the concentration of the Amadori adduct of glucose to lens protein and skin collagen is relatively constant with age, products of sequential glycation and oxidation of protein, termed glycoxidation products, accumulate in these long-lived proteins with advancing age and at an accelerated rate in diabetes. Among these products are the chemically modified amino acids, N epsilon-(carboxymethyl)lysine (CML), N epsilon-(carboxymethyl)hydroxylysine (CMhL), and the fluorescent crosslink, pentosidine. While these glycoxidation products are present at only trace levels in tissue proteins, there is strong evidence for the presence of other browning products which remain to be characterized. Mechanisms for detoxifying reactive intermediates in the Maillard reaction and catabolism of extensively browned proteins are also discussed, along with recent approaches for therapeutic modulation of advanced stages of the Maillard reaction.

Glycation, oxidation, and lipoxidation in the development of the complications of diabetes: a carbonyl stress hypothesis

Modifications of extant plasma proteins, structural proteins,and other macromolecules are enhanced in diabetes because of increased glycation (secondary to increased glucose concentrations) and perhaps because of increased oxidative stress, Increased glycation is present from the time of onset of diabetes, but the relation between diabetes and oxidative stress is less clear: increased oxidative stress may occur later in the course of disease, as vascular damage becomes established, or it may be a feature of uncomplicated diabetes, The combined effects of protein modification by glycation and oxidation may contribute to the development of accelerated atherosclerosis in diabetes and to the development of microvascular complications, Thus, even if not increased by diabetes, variations in oxidative stress may modulate the consequences of hyperglycemia in individual diabetic patients, In this review, the close interaction between glycation and oxidative processes is discussed, and the theme is developed that the most significant modifications of proteins are the result of interactions with reactive carbonyl groups, While glucose itself contains a carbonyl group that is involved in the initial glycation reaction, the most important and reactive carbonyls are formed by free radical-oxidation reactions damaging either carbohydrates (including glucose itself) or lipids, The resulting carbonyl-containing intermediate products then modify proteins, yielding "glycoxidation" and "lipoxidation" products, respectively, This common pathway for glucose and lipid-mediated stress, which may contribute to diabetic complications, is the basis for the carbonyl stress hypothesis for the development of diabetic complications.

Pleistocene and Holocene glacier fluctuations upon the Kamchatka Peninsula

This review summarises landform records and published age-estimates (largely based upon tephrochronology) to provide an overview of glacier fluctuations upon the Kamchatka Peninsula during the Holocene and, to a lesser degree, earlier phases of glaciation. The evidence suggests that following deglaciation from the Last Glacial Maximum (LGM), the peninsula experienced numerous phases of small-scale glacial advance. During the Late Glacial, moraine sequences appear to reflect the former presence of extensive glaciers in some parts of the peninsula, though little chronological control is available for deposits of this period. During the Holocene, the earliest and most extensive phase of advance likely occurred sometime prior to c. 6.8 ka, when glaciers extended up to 8 km beyond their current margins. However, these deposits lack maximum age constrains, and pre-Holocene ages cannot be discounted. Between c. 6.8 ka and the onset of ‘Neoglaciation’ c. 4.5 ka, there is little evidence of glacial advance upon the peninsula, and this period likely coincides with the Holocene climatic optimum (or ‘hypsithermal’). Since c. 4.5 ka, numerous moraines have been deposited, likely reflecting a series of progressively less extensive phases of ice advance during the Late Holocene. The final stage of notable ice advance occurred during the Little Ice Age (LIA), between c. 1350 and 1850 C.E., when reduced summer insolation in the Northern Hemisphere likely coincided with solar activity minima and several strong tropical volcanic eruptions to induce widespread cooling. Following the LIA, glaciers upon the peninsula have generally shown a pattern of retreat, with accelerated mass loss in recent decades. However, a number of prominent climatically and non-climatically controlled glacial advances have also occurred during this period. In general, there is evidence to suggest that millennial scale patterns in the extent and timing of glaciation upon the peninsula (encompassing much of the last glacial period) are governed by the extent of ice sheets in North America. Millennial-to-centennial scale fluctuations of Kamchatkan glaciers (encompassing much of the Holocene) are governed by the location and relative intensity of the Aleutian Low and Siberian High pressure systems. Decadal scale variations in glacier extent and mass balance (particularly since the LIA) are governed by inter-decadal climatic variability over the North Pacific (as reflected by the Pacific Decadal Oscillation), alongside a broader trend of hemispheric warming.

Impact of Testing Procedure on Permeability of Compacted Soils

The commonly used British Standard constant head triaxial permeability (BS) test, for permeability testing of fine grained soils, is known to have a relatively long test duration. Consequently, a reduction in the required time for permeability test provides potential cost savings, to the construction industry (specifically, for use during Construction Quality Control (CQA) of landfill mineral liners). The purpose of this article is to investigate and evaluate alternative short duration testing methods for the measurement of the permeability of fine grained soils.

As part of the investigation the feasibility of an existing method of short duration permeability test, known as the Accelerated Permeability (AP) test was assessed and compared with permeability measured using British Standard method (BS) and Ramp Accelerated Permeability (RAP). Four different fine grained materials, of a variety of physical properties were compacted at various moisture contents to produced analogous samples for testing using three the three different methodologies. Fabric analysis was carried out on specimens derived from post-test samples using Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscope (SEM) to assess the effects of testing methodology on soil structure. Results showed that AP testing in general under predicts permeability values derived from the BS test due to large changes in structure of the soil caused by AP test methodology, which is also validated using MIP and SEM observations. RAP testing, in general provides an improvement to the AP test but still under-predicts permeability values. The potential savings in test duration are shown to be relatively minimal for both the AP and RAP tests.

Measurement of permeability using a bench-top centrifuge

The commonly used British Standard constant head triaxial permeability test for testing of fine-grained soils is relatively time consuming. A reduction in the required time for soil permeability testing would provide potential cost savings to the construction industry, particularly in the construction quality assurance of landfill clay liners. The purpose of this paper is to evaluate an alternative approach of measuring permeability of fine-grained soils benefiting from accelerated time scaling for seepage flow when testing specimens in elevated gravity conditions provided by a centrifuge. As part of the investigation, an apparatus was designed and produced to measure water flow through soil samples under conditions of elevated gravitational acceleration using a small desktop laboratory centrifuge. A membrane was used to hydrostatically confine the test sample. A miniature data acquisition system was designed and incorporated in the apparatus to monitor and record changes in head and flow throughout the tests. Under enhanced gravity in the centrifuge, the flow through the sample was under ‘variable head' conditions as opposed to ‘constant head' conditions as in the classic constant head permeability tests conducted at 1 g . A mathematical model was developed for analysis of Darcy's coefficient of permeability under conditions of elevated gravitational acceleration and verified using the results obtained. The test data compare well with the results on analogous samples obtained using the classical British Standard constant head permeability tests.

Cheetahs, Acinonyx jubatus, balance turn capacity with pace when chasing prey

Predator–prey interactions are fundamental in the evolution and structure of ecological communities. Our understanding, however, of the strategies used in pursuit and evasion remains limited. Here, we report on the hunting dynamics of the world's fastest land animal, the cheetah, Acinonyx jubatus. Using miniaturized data loggers, we recorded fine-scale movement, speed and acceleration of free-ranging cheetahs to measure how hunting dynamics relate to chasing different sized prey. Cheetahs attained hunting speeds of up to 18.94 m s-1 and accelerated up to 7.5 m s-2 with greatest angular velocities achieved during the terminal phase of the hunt. The interplay between forward and lateral acceleration during chases showed that the total forces involved in speed changes and turning were approximately constant over time but varied with prey type. Thus, rather than a simple maximum speed chase, cheetahs first accelerate to decrease the distance to their prey, before reducing speed 5–8 s from the end of the hunt, so as to facilitate rapid turns to match prey escape tactics, varying the precise strategy according to prey species. Predator and prey thus pit a fine balance of speed against manoeuvring capability in a race for survival.

Condition Assessment and Preservation of Open-Air Rock Art Panels During Climate Change

Thousands of Neolithic and Bronze Age open-air rock art panels exist across the countryside in northern England. However, desecration, pollution, and other factors are threatening the survival of these iconic stone monuments. Evidence suggest that rates of panel deterioration may be increasing, although it is not clear whether this is due to local factors or wider environmental influences accelerated by environmental change. To examine this question, 18 rock art panels with varied art motifs were studied at two major panel locations at Lordenshaw and Weetwood Moor in Northumberland. A condition assessment
tool was used to first quantify the level of deterioration of each panel (called “staging”). Stage estimates then were compared statistically with 27 geochemical and physical descriptors of local environments, such as soil moisture, salinity, pH, lichen coverage, soil anions and cation levels, and panel orientation, slope, and standing height. In parallel, climate modelling was performed using UKCP09 to assess how projected climatic conditions (to 2099) might affect the environmental descriptors most correlated with elevated stone deterioration. Only two descriptors significantly correlated (P < 0.05) with increased stage: the standing height of the panel and the exchangeable cation content of the local soils, although moisture conditions also were potentially influential at some panels. Climate modelling predicts warming temperatures, more seasonally variable precipitation, and increased wind speeds, which hint stone deterioration could accelerate in the future due to increased physiochemical weathering. We recommend key panels be targeted for immediate management intervention, focusing on reducing wind exposures, improving site drainage, and potentially immobilizing soil salts.

Comparison of sample preparation methods, validation of an UPLC-MS/MS procedure for the quantification of tetrodotoxin present in marine gastropods and analysis of pufferfish

Tetrodotoxin (TTX) is one of the most potent marine neurotoxins reported. The global distribution of this toxin is spreading with the European Atlantic coastline now being affected. Climate change and increasing pollution have been suggested as underlying causes for this. In the present study, two different sample preparation techniques were used to extract TTX from Trumpet shells and pufferfish samples. Both extraction procedures (accelerated solvent extraction (ASE) and a simple solvent extraction) were shown to provide good recoveries (80-92%). A UPLC-MS/MS method was developed for the analysis of TTX and validated following the guidelines contained in the Commission Decision 2002/657/EC for chemical contaminant analysis. The performance of this procedure was demonstrated to be fit for purpose. This study is the first report on the use of ASE as a mean for TTX extraction, the use of UPLC-MS/MS for TTX analysis, and the validation of this method for TTX in gastropods.

Acceleration of ions up to 20MeV/nucleon in the ultrashort, high-intensity regime

The measurements reported here provide scaling laws for the ion acceleration process in the regime of ultrashort (50 fs), ultrahigh contrast (10) and ultrahigh intensity (> 10W/cm ), never investigated previously. The scaling of the accelerated ion energies was studied by varying a number of parameters such as target thickness (down to 10nm), target material (C and Al) and laser light polar- ization (circular and linear) at 35° and normal laser incidence. A twofold increase in proton energy and an order of magnitude enhancement in ion flux have been observed over the investigated thickness range at 35° angle of incidence. Further- more, at normal laser incidence, measured peak proton energies of about 20 MeV are observed almost independently of the target thickness over a wide range (50nm- 10 µm). 1. © 2012 by Società Italiana di Fisica.