bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of clot structure in gradient‐echo magnetic resonance imaging of hematoma
Authors: Taber Katherine H. , Hayman L. Anne , Herrick Richard C. , Kirkpatrick Joel B. 
Published: March 2007

AbstractThe MR appearance of clots with different internal structures was compared on gradient‐echo (GE) and spin‐echo (SE) images. After MR imaging, clots were submitted for histological analysis to allow direct correlation of clot structure with MR image intensity. Normal heterogeneous clots (containing entrapped serum) were hypointense compared to both unclotted blood (Hct 45) and brain on GE MR images. Homogeneous (serum‐poor) clots and settled blood were hyperintense to unclotted blood and isointense or hyperintense to brain. These results indicate that the GE technique is quite sensitive to the physical inhomogeneity created (at the voxel level) when blood forms an inhomogeneous clot containing relatively large islands of red blood cells (RBCs) surrounded by lakes of serum. The effect of the different possible clot structures on GE signal intensity thus provides an etiology for the previously unexplained observations of hemorrhage with high signal intensity on GE MR images.
Quantitative measurements with localized 1H MR spectroscopy in children with Canavan's disease
Authors: Wittsack H.‐J. , Kugel Harald , Roth B. , Heindel W. 
Published: March 2007

AbstractCanavan's disease is an autosomal recessive hereditary leukodystrophy resulting from deficiency of the enzyme aspartoacylase. Two children suffering from this metabolic brain disease were examined using image‐guided localized proton spectroscopy. The absolute concentrations of metabolites were determined. These data demonstrate, for the first time, that the well known increase of the N‐Acetylaspartic acid (NAA)/Cho ratio in this disease may be not only due to a reduction of choline‐containing compounds in brain tissue but, at least in specific cases, also due to an increase of the NAA concentration, which is a result of the enzyme defect.
Fourier registration of three‐dimensional brain MR images: Exploiting the axis of rotation
Authors: Kassam Ariff , Wood Michael L. 
Published: March 2007

AbstractWe have developed a novel algorithm to register three‐dimensional MR images that have undergone rigid body motion. The most interesting feature of the algorithm is that it reduces a general three‐dimensional rotation to a simple planar rotation by finding the axis of rotation. The algorithm, which is a nontrivial three‐dimensional extension of existing Fourier registration algorithms, has been tested on 30 artificially misaligned MR images of a phantom, four artificially misaligned MR images of a brain, and one case of actual patient motion. The algorithm successfully registered every image. The registration error for a voxel 10 cm from the origin for the artificially misaligned phantom images was 2.8 mm at most and had a mean of 1.2 mm and standard deviation of .7 mm. The registration parameters for the images contaminated by actual patient motion were similar to that from an established image registration algorithm. The results indicate that the algorithm is accurate, reliable, and fast. The rigid body model requires the brain to be segmented from MR images of the head before registration.
Influence of model melanoidins on calcium‐dependent transport mechanisms in smooth muscle tissue
Authors: Stefanova Iliyana D. , Argirova Mariana D. , Krustev Athanas D. 
Published: March 2007

AbstractMelanoidins obtained from L‐arginine and D‐glucose (MW > 3500 Da) were tested for their ability to influence the contractility of gastric smooth muscles. A study within the range 0.1–10 mg/mL revealed that at low concentrations, the melanoidins provoked concentration‐dependent contraction, whereas a muscle relaxation was registered at high concentrations. The contraction was preceded by changes in the calcium membrane current as measured by single sucrose‐gap method and significantly attenuated by the calcium channel blockers D‐600 and nifedipine. Measurements with Ca2+‐selective electrode showed that the melanoidins decreased the concentration of ionized Ca2+ in tissue bath in concentration‐dependent manner. Experiments carried out in solutions with lower than normal Ca2+ concentration and using melanoidins preliminary saturated with Ca2+ confirmed that the calcium chelation by melanoidins was a key contributing cause for the development of relaxant response. The results obtained showed that the melanoidins could influence the contractility of smooth muscles through at least two pathways: at low concentrations they caused depolarization and activation of L‐type calcium channels, stimulated the Ca2+ influx, and provoked contraction, whereas at high concentrations calcium binding by melanoidins led to significant depletion of extracellular calcium ions and contributed to the relaxation process observed.
Proteolysis of milk proteins lactosylated in model systems
Authors: Kastrup Dalsgaard Trine , Holm Nielsen Jacob , Bach Larsen Lotte 
Published: March 2007

AbstractFive different milk proteins (α‐casein, β‐casein, κ‐casein, β‐lactoglobulin, and lactoferrin) and a peptide substrate were applied as substrates for the investigation of how lactosylation affected proteolysis by different proteases. After a lactosylation period of 4 days in aqueous solution, at 65°C and pH 6.8 in a protein: lactose ratio of 1000 the proteins were enzymatically hydrolyzed by the three milk relevant proteases plasmin, cathepsin D, and chymosin. Lactosylation of all substrates affected hydrolysis by plasmin negatively, with the largest effect on the globular proteins. This could be explained by modification of lysine residues, being the preferred cleavage site for plasmin, but also the residue generally preferred for lactosylation. Lactosylation of the caseins and of β‐lactoglobulin did not affect subsequent cleavage by cathepsin D and chymosin significantly, but for β‐lactoglobulin, both the secondary as well as the tertiary structure were affected by lactosylation. In contrast, decreased hydrolysis by cathepsin D and chymosin was observed for lactoferrin after lactosylation. Decreased hydrolysis may be caused by a more compact tertiary structure induced by lactosylation of lactoferrin, as indicated by fluorescence spectroscopy measurements.
Modeling of acrylamide formation and browning ratio in potato chips by artificial neural network
Authors: Serpen Arda , Gökmen Vural 
Published: March 2007

AbstractThe artificial neural network (ANN) modeling approach was used to predict acrylamide formation and browning ratio (%) in potato chips as influenced by time×temperature covariants. A series of feed‐forward type network models with back‐propagation training algorithm were developed. Among various network configurations, 4‐5‐3‐2 configuration was found as the best performing network topology. Four neurons in the input layer were reflecting the asparagine concentration, glucose concentration, frying temperature, and frying time. The output layer had two neurons representing acrylamide concentration and browning ratio of potato chips. The ANN modeling approach was shown to successfully predict acrylamide concentration (R = 0.992) and browning ratio (R = 0.997) of potato chips during frying at different temperatures in time‐dependent manner for potatoes having different concentrations of asparagine and glucose. It was concluded that ANN modeling is a useful predictive tool which considers only the input and output variables rather than the complex chemistry.
Inhibition of polyphenoloxidase activity by mixtures of heated cysteine derivatives with carbonyl compounds
Authors: Chériot Sophie , Billaud Catherine , Maillard Marie‐Noëlle , Nicolas Jacques 
Published: March 2007

AbstractIt had previously been shown that soluble Maillard reaction products (MRP) made from thiol compounds and glucose or fructose contained powerful inhibitors of various fruit and vegetable polyphenoloxidase (PPO) activity. In MRP from cysteine and glucose, the amount of hydroxymethylfurfural (HMF) formed increased with the increase in glucose concentration (0–1 M), particularly under acidic (pH 2) conditions. Using model mixtures containing a preheated cysteine‐derived compound and a carbonyl component, especially HMF, furfural and benzaldehyde, we showed that the neoformed compounds produced exhibited a stronger inhibitory potency toward PPO activity of eggplant, apple, and mushroom than former MRP. Optimal reaction conditions for the formation of inhibitory compounds when HMF reacted with preheated cysteine were investigated. It was found that a reactants molar ratio of 1:1 and a reaction time exceeding 1 h were the most efficient reaction conditions to generate inhibitory compounds. The stability of the newly formed products, evaluated during storage, showed that their inhibitory potency was globally kept at 4, 21, and 37°C for 72 h but was unstable when stored at –20°C and lost when exposed to UV radiations for 24 h.
Lung level of HMBG1 is elevated in response to advanced glycation end product‐enriched food in vivo
Authors: Bartling Babett , Fuchs Christine , Somoza Veronika , Niemann Bernd , Silber Rolf‐Edgar , Simm Andreas 
Published: March 2007

AbstractHigh mobility group box protein 1 (HMGB1) is a ubiquitous nuclear protein that can be actively released from the cell in certain conditions thereby mediating cytokine‐like function. While nuclear HMGB1 modulates the transcriptional activity of cells, extracellular HMGB1 partially acts via binding to the receptor for advanced glycation end products (RAGE), which is highly expressed in lung tissue. Therefore, we studied the impact of food‐derived advanced glycation end products (AGEs), the Maillard reaction products, on the lung expression of HMGB1. Feeding rats with AGE‐rich diet, containing either bread crust or coffee beverage, resulted in an upregulation of HMGB1 mRNA and protein especially in those animals receiving bread crust diet. The expression of RAGE was not influenced. Moreover, we revealed a positive correlation between an increased lung AGE level and HMGB1 protein expression in both animal groups receiving either bread crust or coffee extract but not in the control group. In contrast, the ageing‐related AGE accumulation was not associated with an increased level of HMGB1 protein in lung tissue from senescent (100 wk) compared to young‐adult (24 wk) rats. Our data suggest a physiological role of food‐ but not ageing‐associated AGEs in the regulation of the HMGB1 expression in lung.
Off‐line liquid chromatography‐MALDI by with various matrices and tandem mass spectrometry for analysis of glycated human serum albumin tryptic peptides
Authors: Lapolla Annunziata , Brancia Francesco L. , Bereszczak Jessica , Fedele Domenico , Baccarin Lorenzo , Seraglia Roberta , Traldi Pietro 
Published: March 2007

AbstractAdvanced glycation end‐product (AGE)/peptides, arising from in vivo digestion of glycated proteins, are biologically important compounds, due to their reactivity against circulating and tissue proteins. For information on their possible structure, in vitro glycation of HSA and its further enzymatic digestion were performed. The resulting digestion product mixture was analysed directly by MALDI MS with various matrices [2,5‐dihydroxy benzoic acid (DHB) and α‐cyano‐4‐hydroxy cinnamic acid (CHCA)]. Alternatively, offline microbore LC prior to MALDI analysis was used, and showed that 63% of the free amino groups prone to glycation are modified, indicating the contemporary presence of unglycated peptides. This result proves that, regardless of the high glucose concentration employed for HSA incubation, glycation does not go to completion. Further studies showed that the collisionally activated decomposition of singly charged glycated peptides leads to specific fragmentation pathways, all related to the condensed glucose molecule. These unique product ions can be used as effective markers to establish the presence of a glucose molecule within a peptide ion.
Interactive coronary MRI
Authors: Hardy Christopher J. , Darrow Robert D. , Pauly John M. , Ken Adam B. , Dumoulin Charles L. , Hu Bob S. , Martin Kenneth M. 
Published: March 2007

AbstractThe acquisition of complete three‐dimensional (3D), segmented gradient‐echo data sets to visualize the coronary arteries can be both time consuming and sensitive to motion, even with use of multiple breath‐holding or respiratory gating. An alternate hybrid approach is demonstrated here, in which real‐time interactive imaging is first used to locate an optimal oblique coronary scan plane. Then, a limited number of contiguous slices are acquired around that plane within a breath‐hold with use of two‐dimensional (2D) segmented gradient‐echo imaging. Dual inversion nulling is used to suppress fat and myocardium. Finally, if needed, a limited reformat of the data is pelformed to produce images from relatively long sections of the coronaries. This approach yields relatively rapid visualization of portions of the coronary tree. Several different methods are compared for interactively moving the scan plane.
MR microscopy of transgenic mice that spontaneously acquire experimental allergic encephalomyelitis
Authors: Ahrens Eric T. , Laidlaw David H. , Readhead Carol , Brosnan Celia F. , Fraser Scott E. , Jacobs Russell E. 
Published: March 2007

AbstractPathology of fixed spinal cords from transgenic mice with a myelin basic protein (MBP) specific T cell receptor was investigated. These mice spontaneously acquire the demyelinating disease experimental allergic encephalomyelitis (EAE). Several complementary imaging modalities, all on the same tissues, were used to visualize lesions; these included high‐field (11.7‐T) microscopic diffusion tensor imaging (DTI),T‐weighted imaging, and optical microscopy on histological sections. Lesions were predominantly in white matter around meninges and vasculature and appeared hyperintense in anatomical images. DTIs showed reduced diffusion anisotropy in the same hyperintense regions, consistent with inflammation and edema. Histology in the same tissues exhibited the characteristic pathology of EAE. Two techniques for visualizing the effective diffusion tensor fields are presented, which display direction, organization, and integrity of neuronal fibers. It is shown that DTI offers intriguing possibilities for visualizing axonal organization and lesions within white matter.
Small particles of fusinite and carbohydrate chars coated with aqueous soluble polymers: Preparation and applications for in Vivo EPR oximetry
Authors: Gallez Bernard , Debuyst René , Dejehet Fernand , Liu Ke J. , Walczak Tadeusz , Goda Fuminori , Demeure Roger , Taper Henryk , Swartz Harold M. 
Published: March 2007

AbstractThe development of oxygen‐sensitive paramagnetic materials is being pursued actively because of their potential applications in in vivo EPR oximetry. Among these materials, several charcoals and carbohydrate chars are of special interest because of their desirable EPR properties: high sensitivity of the EPR linewidth to the partial pressure of oxygen, simple EPR spectra, and high spin density. Their potential use in humans, however, is limited by the need to demonstrate that they will not lead to deleterious effects. A strategy was used to optimize the biocompatibility of the oxygen‐sensitive materials by decreasing the size of the particles and coating them with suspending or surfactive agents such as arabic gum, polox‐amer (Pluriol 6800®), and polyvinylpyrrolidone. The coated particles of a carbohydrate char and fusinite were characterized in vitro for their size, stability, and pO2 sensitivity. The feasibility of performing pO2 measurement was examined in vivo by inducing ischemia in the gastrocnemius muscle of mice. The use of arabic gum for coating the fusinite particles preserved the pO2 sensitivity in vivo, whereas the other surfactive agents led to a loss of the pO2 sensitivity in vivo. Small particles of fusinite coated by arabic gum and intravenously administered to mice accumulated in the liver, whereas the uncoated fusinite was toxic when injected intravenously due to the large size and aggregation of the particles. Histological studies performed up to 6 months after the injection in muscles of mice did not indicate any toxicity from the materials used in the present study.
Anisotropically weighted MRI
Authors: Shrager Richard I. , Basser Peter J. 
Published: March 2007

AbstractThe intensity of an isotropically weighted MR image is proportional to a rotationally invariant measure of bulk diffusion, TraceD (where D is the effective diffusion tensor). Such images can be acquired from as few as two diffusion‐weighted images (DWIs). Analogously, the intensity of an anisotropically weighted MR image is proportional to a rotationally invariant measure of diffusion anisotropy derived from D, such as the variance of the principal diffusivities of D. By using linear algebra, we show that to produce an anisotropically weighted MR image requires acquiring at least seven DWls, which is also the minimum number of DWls sufficient to estimate the entire diffusion tensor, as well as the T2‐weighted amplitude image, A(b = 0), in each voxel. A general mathematical framework for constructing isotropically weighted and anisotropically weighted MR images is also provided.
29Si imaging of silicone breast implants and intraocular silicone oil
Authors: Haselhorst Reta , Scheffler Klaus , Faletti Leonardo , Kaspar Armin , Prünte Christian , Seelig Joachim 
Published: March 2007

AbstractSilicon‐29 (29Si) imaging was investigated as a potential imaging modality for monitoring silicone prostheses in humans. The 29Si relaxation times of several silicone gels were measured and found to average T1 = 21.2 ± 1.5 s and T2 = 207 ± 40 ms, with no significant difference between virgin and explanted gels. A single‐shot half‐Fourier rapid acquisition with relaxation enhancement (RARE) and a refocused gradientecho sequence were used for acquiring 29Si images with 5 × 5 mm2 resolution and no slice selection. Three volunteers with silicone‐gel‐filled breast implants and one subject with an intraocular silicone oil injection were thus examined in a total acquisition time of 10–15 min per image. On all 29Si images, the shape of the silicone object was well depicted. Although at present, conventional proton images are superior in resolution and signal‐to‐noise ratio, 29Si imaging has the advantage of optimal specificity, since only the silicone itself is visible.
Fast 1H spectroscopic imaging using a multi‐element head‐coil array
Authors: Schäffter Tobias , Börnert Peter , Leussler Christoph , Carlsen Ingwer C. , Leibfritz Dieter 
Published: March 2007

AbstractFast proton magnetic resonance spectroscopic imaging (MRSI) using a multi‐element head‐coil array is examined with respect to three aspects: the coil design, the use of an appropriate signal combination method, and the design of the MRSl pulse sequence itself. An eight‐element head‐coil array has been developed to increase the signal‐to‐noise ratio (SNR) of MRSl in the human brain. The flexible wraparound design optimally fits different head sizes and thus provides high sensitivity. The signal combination of the individual coil elements is based on the approach proposed by Roemer et al. Magn. Reson. Med. 16, 192 (1990). An additional short prescan is performed to provide a good estimate of the complex coil sensitivity profiles, which are used in the signal combination procedure to correct the spectroscopic imaging data for the spatially varying intensity. The use of coil arrays in MRSI has some effect on the requirements for both water and lipid suppression. These techniques and a MRSl pulse sequence that provides a high spectroscopic resolution are described and discussed. Experimental results at 1.5 T show that metabolite maps of N‐acetylaspartate (NAA), choline (Cho), phosphocreatine (PCr)/creatine (Cr) can be obtained within a 5‐min acquisition time.
Simultaneous highly selective MR water and fat imaging using a simple new type of spectral‐spatial excitation
Authors: Schick Fritz 
Published: March 2007

AbstractIn a recent contribution [MRM 38:269–274 (1997)], it was reported that an excitation by a series of sinc‐shaped slice‐selective RF pulses with binomial amplitude ratios and complete spin refocusing between consecutive pulses leads to water‐ or fat‐selective images of high quality. A method for simultaneous water and fat imaging in multislice operation is presented based on the principle of alternated line scanning and linear superposition of several excitations. For example, a 1‐3‐3‐1 pulse train with suitable interpulse delays results in a water‐selective excitation, whereas a 1 ‐ 3 ‐ 3 ‐ 1 train leads to a selective excitation of fat (transmitter frequency corresponds with the Larmor frequency of water protons). Phase cycling of the excitation (1 ‐ 3 ‐ 3 ‐1 for the even line numbers in k‐space, but 1 ‐ 3 ‐ 3 ‐1 for the odd line numbers) causes a shift of n/2 lines in phase‐encode direction for the fat signals in an n × m matrix. The principle of linear superposition explains why an excitation of 2 ‐ 0 ‐ 6 ‐ 0 for the even lines and 0 ‐ 6 ‐ 0 ‐ 2 for the odd lines results in a final image with unshifted water signals and shifted fat signals. Both water and fat portions are simultaneously exhibited and separated without any signal loss. Examples recorded by a gradient‐echo sequence demonstrate the potential of the new technique that allows a reduction of up to 50% of measuring time compared with former frequency‐selective imaging methods.
Amplitude response and stimulus presentation frequency response of human primary visual cortex using BOLD EPI at 4 T
Authors: Thomas Christopher G. , Menon Ravi S. 
Published: March 2007

AbstractDetailed measurement of the neural response to flicker frequency using functional MRI (fMRI) were made. The fMRl signal peaks at a flicker frequency of 8 Hz in human V1, in agreement with previous positron emission tomography (PET) and fMRl experiments. The modulation amplitude of the hemodynamic response to varying continuous periods of flicker stimulation was measured. The hemodynamic response was not observed to be modulated by neural modulation for periods shorter than 6.7 s. The resemblance between the BOLD response to the stimulus presentation frequency and the base‐line power spectra at the same frequencies suggests that the same underlying mechanism could be responsible for both curves and that the base‐line fMRl power spectrum is probably due to base‐line electrical activity in the brain. The integrals of the resting base‐line power spectrum, the background power spectrum, the respiration component, and the cardiac component were found to be linearly dependent on TE.
Visualizing blood flow patterns using streamlines, arrows, and particle paths
Authors: Buonocore Michael H. 
Published: March 2007

AbstractA customized computer program (MRIView) is described for visualizing and quantifying complex blood flow patterns in major vessels, using nongated and cardiac‐gated three‐dimensional (3D) velocity data obtained with MR velocity‐encoded phase pulse sequences. Streamlines, arrows, and particle paths (collectively referred to as “paths”) can be computed interactively, using both forward and backward time integration of the velocity field. The program provides interactive cross‐sectional and 3D perspective visualization of the paths, with quantification and statistical analysis of average speed, through‐plane velocity, cross‐sectional area, and flow. Normal flow patterns in the carotid artery, basilar artery tip, ascending aorta, coronary arteries, descending aorta, and renal arteries, as well as abnormal flow patterns in basilar tip aneurysms, have been investigated. The program revealed flow patterns in these regions with features that are well known from Doppler ultrasound and other features that have not been reported previously. The association between specific abnormal flow patterns and development of atherosclerosis suggests that particle paths can be used to assess risk of plaque formation and progression, as well as to evaluate flow dynamics and vascular patency before and after vascular interventions.