Changes of molecular dynamics in the α-to-β transition associated with amyloid fibril formation were explored on apomyoglobin (ApoMb) as a model system. Circular dichroism, neutron and X-ray scattering experiments were performed as a function of temperature on the protein, at different solvent conditions. A significant change in molecular dynamics was observed at the α-to-β transition at about 55°C, indicating a more resilient high temperature β structure phase. A similar effect at approximately the same temperature was observed in holo-myoglobin, associated with partial unfolding and protein aggregation. A study in a wide temperature range between 20 and 360 K revealed that a dynamical transition at about 200 K for motions in the 50 ps time scale exists also for a hydrated powder of heat-denatured aggregated ApoMb.

The dynamic structure factor of vitreous silica is measured at terahertz frequencies by inelastic scattering of x rays (IXS) and neutrons (INS). The IXS experiment is performed at exchanged wave vectors q between 4 and 15 nm(-1) and at temperatures above and below the glass transition. The neutron time-of-flight technique is used as a high-resolution probe in a comparable q region. The data analysis confirms the presence of two inelastic features in the IXS spectra in the entire explored wave-vector range. The lower-frequency component is nondispersive and is observed by both IXS and INS around the boson peak frequency. The higher-frequency one, associated with the longitudinal-acoustic-like branch, is marked by a positive dispersion, confirming the results of a previous study [Ruzicka , Phys. Rev. B 69, 100201 (2004)]. As q increases, the vibrational modes of the disordered structure progressively lose their plane-wave character; for q around that of the first sharp diffraction peak, the dynamic structure factor converges to an effective density of vibrational states. The contribution of the terahertz vibrations to the thermal conductivity of vitreous silica is then evaluated by means of a Kubo-type formula for the diffusivity in disordered systems. The acousticlike modes that persist at terahertz frequencies represent a heat conduction channel which accounts for only a fraction, although relevant, of the thermal conductivity. The failure of this approach to fully describe the conductivity data is attributed to the nondiagonal elements of the heat current operator that are not experimentally accessible.

The incoherent approximation for the determination of the vibrational density of states of glasses from inelastic neutron or x-ray scattering data is extended to treat the coherent scattering. The method is applied to new room temperature measurements of vitreous silica and germania on the thermal time-of-flight spectrometer IN4 at the High Flux Reactor in Grenoble. The inelastic dynamic structure factor at the boson peak turns out to agree reasonably well with simulation results, but the long-wavelength fraction exceeds the expectation of the Debye model, in particular, in germania.

A combined inelastic X-ray and neutron scattering experiment is performed on the prototypical glass vitreous silica. The complementarity of the two techniques is exploited to determine the dynamic structure factor in a wide range of energies and wavevectors. The vibrational-mode spectral density is then used to compute the high-temperature thermal conductivity. The acoustic-like modes persisting at THz frequencies are shown to represent a relevant heat conduction channel, although they cannot account for the entire thermal conductivity.

Changes of molecular dynamics in the alpha-to-beta transition associated with amyloid fibril formation were explored on apomyoglobin (ApoMb) as a model system. Circular dichroism, neutron and X-ray scattering experiments were performed as a function of temperature on the protein, at different solvent conditions. A significant change in molecular dynamics was observed at the alpha-to-beta transition at about 55A degrees C, indicating a more resilient high temperature beta structure phase. A similar effect at approximately the same temperature was observed in holo-myoglobin, associated with partial unfolding and protein aggregation. A study in a wide temperature range between 20 and 360 K revealed that a dynamical transition at about 200 K for motions in the 50 ps time scale exists also for a hydrated powder of heat-denatured aggregated ApoMb.

Raman scattering measurements of vitreous SiO2 were performed over a wide range of temperatures in order to study the behavior of the boson peak and the quasielastic scattering. The analysis of quasielastic contribution in the framework of the Jackle model demonstrates that the quasielastic excess and the acoustic attenuation have the same physical origin. Moreover and even more importantly we found that the boson peak decrease, which is observed at increasing temperature, is fully explained by the modification of the elastic constants.

The acoustic attenuation of vitreous germania (v-GeO2) has been measured over more than three decades in frequency, by means of neutron scattering at high-frequency (THz), visible light scattering and the newly developed technique of Brillouin ultraviolet scattering at lower frequencies (15-50 GHz). The experiments are supported by a molecular dynamics study of a simulated sample of v-GeO2. The temperature dependence, from 80 K up to the glass transition temperature, shows a persistence of the dynamical nature of the attenuation in the GHz range and a simultaneous increase of the contribution coming from the structural disorder. At higher frequencies clear evidences of a crossover to a region where the attenuation is induced only by the topological disorder are found. Copyright (C) EPLA, 2007.

A close inspection of neutron spectra of glass formers in the frequency region above the boson peak does not show the constant eigenvalue density expected for a random dynamical matrix, but a slow decrease towards higher eigenvalues. In 1,4-polybutadiene and selenium, the slope becomes steeper with increasing temperature in the undercooled liquid, suggesting an influence of the vibrational entropy. One can describe the behaviour quantitatively in terms of a balance between level repulsion (from the randomness of the dynamical matrix) and vibrational entropy. On the basis of this evidence, the boson peak must be a crossover from such a balance at higher frequencies to a mixture of sound waves and additional excitations at low frequency.

We report new inelastic Raman and neutron scattering spectra for glasses with different degrees of fragility, v- SiO2, v- GeO2, (AgI)(0.5) (Ag2O-B2O3)(0.5), (AgI)(x)(AgPO3)(1-x). The data are compared for each sample to obtain the Raman coupling function C(omega). The study indicates a general linear behaviour of C(omega) near the boson peak maximum, and evidences a correlation between vibrational and relaxational properties, confirming the results of recent publications.

The temperature dependence of the mean square displacement, (it 2), calculated by elastic neutron scattering for two phosphate glasses, (AgI)(x)(AgPO3)(1-x) with x = 0.3, 0.55, is analysed. The studied samples are probed in a wide range of temperatures going from a few tens of K up to the glass transition temperature and well into the undercooled liquid state. In the low temperature regime a solid like behaviour appears, showing a linear temperature dependence of the Debye-Waller factor, while around T, the onset of a pronounced increase of < u(2)> is observed. The temperature dependence of the normalized elastic intensity and the drawn out Debye-Waller factor are fitted and analyzed by the theoretical previsions of Mode Coupling Theory finding a good agreement. (c) 2006 Elsevier B.V. All rights reserved.

We report inelastic Raman and neutron scattering spectra for the network glass formers vitreous silica (v-SiO2) and vitreous germania (v-GeO2) measured at temperature from 10 to 300K. The ability to determine the temperature dependence of the luminescence background in Raman scattering has allowed to obtain the Raman coupling function C(ω) and in particular, its low-frequency limit. This study indicates that C(ω) has a linear behavior near the Boson peak maximum and below.

INTRODUCTION:Coeliac disease (CD) is associated with an increased risk of non-Hodgkin lymphoma (NHL), but there is little information about whether this is true for clinically silent CD. OBJECTIVE:To investigate the frequency of CD in two European populations; one with NHL and another derived from the general population. METHODS:A prospective, multi-centre, case-control study in 10 European countries was conducted between May 1998 and April 2001. A total of 1446 consecutive patients with newly diagnosed NHL aged over 18 years was collected. The control group consisted of a population of 9676 individuals who were screened for CD. The number of patients with a previous diagnosis of CD and those with silent CD detected by screening were determined in the two groups. RESULTS:The patients with CD had a significantly increased risk of developing NHL [odds ratio (OR) 2.6, 95% confidence interval (CI) 1.4-4.9]. This risk was only present in patients with CD diagnosed clinically before the study (OR 3.3, 95% CI 1.4-7.9), but not in those with silent CD detected by screening (OR 1.3, 95% CI 0.6-2.7). CONCLUSION:Patients with CD have an increased risk of developing NHL, although this is lower than previously thought. Clinically silent CD is rare in patients with NHL.

The high-frequency dynamics of v-GeO2 was investigated by inelastic neutron scattering. Neutron experiments were carried out by exploiting both three-axis and time-of-flight techniques as most adequate to selectively access to a wider kinematics region or to higher-resolution characteristics. Experimental evidences of a highly dispersing inelastic peak, with an associated velocity of 3650 m s−1, and an almost dispersionless inelastic structure allowed us to definitely confirm the propagating nature of the high-frequency excitations. The measured data were compared with the results of a molecular-dynamics simulation.

Measurements of Raman scattering from vitreous silica (spectrosil) in the temperature range 12–1200K are analyzed and compared with inelastic neutron scattering measurements done on the same sample. The results show a temperature dependence of the quasi-elastic scattering. Comparing this study with acoustical attenuation measured at 30GHz by Brillouin light scattering, we found that the mechanism giving rise to quasi-elastic scattering in vitreous silica seems to be the same as the one causing the acoustic attenuation.

OBJECTIVE:To investigate the value of serum antitissue transglutaminase IgA antibodies (IgA-TTG) and IgA antiendomysial antibodies (IgA-EMA) in the diagnosis of coeliac disease in cohorts from different geographical areas in Europe. The setting allowed a further comparison between the antibody results and the conventional small-intestinal histology.METHODS:A total of 144 cases with coeliac disease [median age 19.5 years (range 0.9-81.4)], and 127 disease controls [median age 29.2 years (range 0.5-79.0)], were recruited, on the basis of biopsy, from 13 centres in nine countries. All biopsy specimens were re-evaluated and classified blindly a second time by two investigators. IgA-TTG were determined by ELISA with human recombinant antigen and IgA-EMA by an immunofluorescence test with human umbilical cord as antigen.RESULTS:The quality of the biopsy specimens was not acceptable in 29 (10.7%) of 271 cases and a reliable judgement could not be made, mainly due to poor orientation of the samples. The primary clinical diagnosis and the second classification of the biopsy specimens were divergent in nine cases, and one patient was initially enrolled in the wrong group. Thus, 126 coeliac patients and 106 controls, verified by biopsy, remained for final analysis. The sensitivity of IgA-TTG was 94% and IgA-EMA 89%, the specificity was 99% and 98%, respectively.CONCLUSIONS:Serum IgA-TTG measurement is effective and at least as good as IgA-EMA in the identification of coeliac disease. Due to a high percentage of poor histological specimens, the diagnosis of coeliac disease should not depend only on biopsy, but in addition the clinical picture and serology should be considered.

Journal of Pediatric Gastroenterology and NutritionVolume 39, Issue S1 p. S56-S56 ABSTRACTS: Poster Session Abstracts P0001 PP COELIAC DISEASE IN FINLAND -EVEN MORE COMMON THAN THOUGHT BEFORE K. Mustalahti, K. Mustalahti Paediatric Research Centre, University of Tampere, Tampere, FinlandSearch for more papers by this authorE. Bravi, E. Bravi Eurospital, TriesteSearch for more papers by this authorM. Caradonna, M. Caradonna Eurospital, TriesteSearch for more papers by this authorE. Fabiani, E. Fabiani Paediatric department, University Hospital of Ancona, Ancona, ItalySearch for more papers by this authorC. Catassi, C. Catassi Paediatric department, University Hospital of Ancona, Ancona, ItalySearch for more papers by this authorA. Reunanen, A. Reunanen National Public Health Institute, Helsinki, FinlandSearch for more papers by this authorM. Mäki, M. Mäki Paediatric Research Centre, University of Tampere, Tampere, FinlandSearch for more papers by this author K. Mustalahti, K. Mustalahti Paediatric Research Centre, University of Tampere, Tampere, FinlandSearch for more papers by this authorE. Bravi, E. Bravi Eurospital, TriesteSearch for more papers by this authorM. Caradonna, M. Caradonna Eurospital, TriesteSearch for more papers by this authorE. Fabiani, E. Fabiani Paediatric department, University Hospital of Ancona, Ancona, ItalySearch for more papers by this authorC. Catassi, C. Catassi Paediatric department, University Hospital of Ancona, Ancona, ItalySearch for more papers by this authorA. Reunanen, A. Reunanen National Public Health Institute, Helsinki, FinlandSearch for more papers by this authorM. Mäki, M. Mäki Paediatric Research Centre, University of Tampere, Tampere, FinlandSearch for more papers by this author First published: 01 June 2004 https://doi.org/10.1002/j.1536-4801.2004.tb12431.x Submitted by: [email protected] Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume39, IssueS1June 2004Pages S56-S56 RelatedInformation

Background. So far the reliability of the anti-guinea pig and anti-human tissue transglutaminase antibodies for the coeliac disease diagnosis has been evaluated in selected groups of patients.Aim. To compare the diagnostic accuracy of anti-human versus anti-guinea pig tissue transglutaminase in the coeliac disease screening of the general population.Subjects. Two healthy Italian populations living in Marche region and in Western Sardinia.Methods. Both anti-guinea-pig and anti-human tissue transglutaminase were determined using an enzyme-linked immunosorbent assay-based commercially available kit (Eu-tTG, Eurospital, Trieste, Italy).Results. During the period 1999-2001, 3541 subjects (1500 from "continental" Italy and 2041 from Sardinia) were screened for coeliac disease using both anti-guinea pig and anti-human tissue transglutaminase as first-level tests. Both these tests were negative in 3439/3541 sera, while 29 resulted positive for both of them and 73 showed discordant results. Overall, 50 intestinal biopsies were performed in 22, 21 and 7 subjects with positivity to both screening tests, to anti-guinea pig and to anti-human tissue transglutaminase alone, respectively. A coeliac disease diagnosis was made in 25 subjects giving an overall prevalence of 1:126 individuals. The anti-tissue transglutaminase specificity and sensitivity were 98 and 92% for guinea pig and 99.6 and 96% for human tissue transglutaminase, respectively.Conclusions. The anti-human tissue transglutaminase test should definitely replace the anti-guinea pig-derived one as first-level screening tool for identifying all subjects who need the second-level investigations (small intestinal biopsy). (C) 2004 Editrice Gastroenterologica Italiana S.r.l. Published by Elsevier Ltd. All rights reserved.

Inelastic neutron scattering experiments have been performed in melt-quenched vitreous Germania, v-GeO2, at room temperature. Coherence effects have been observed in the dynamical structure factor over the collective excitations energy range. Indeed, because of the relatively low velocity of sound of this system (3600 m/s), the linear low-q region of the (q,omega) dispersion relationship was accessible to the neutron experiment.The observed effects are consistent with the acoustic-phonon dispersion curves of the corresponding crystal, thus supporting the hypothesis that, also in glassy systems, longitudinal and transverse acoustic branches can be still defined, even if they are broader than in crystals, due to topological disorder. (C) 2004 Elsevier B. V. All rights reserved.

The vibrational dynamic of vitreous germania (v-GeO2) with respect to that of vitreous silica (v-SiO2) has been investigated by means of several inelastic and elastic scattering experiments. These amorphous systems belong to the large family of continuous random network forming glasses. In spite of their topological similarity, some dynamical differences have been singled out. We present experimental data on light Raman scattering at room temperature as well as new elastic and inelastic neutron scattering. Transversal-acoustic character of the vibrations responsible for the density of states excess in the Boson peak energy range is found.