ABSTRACT
Trauma is one of the leading causes of mortality in pregnant women and significantly increases the likelihood of an unwanted termination of pregnancy. Particularly in severe trauma with an increased risk of significant maternal injuries, computed tomography (CT) remains the imaging modality of choice as it is comprehensively available, quick to carry out and has a high diagnostic accuracy in the detection and classification of life-threatening trauma-associated pathologies compared to other imaging techniques. Considering the radiation-associated risks, it is unlikely that a single, monophasic CT in the emergency trauma room will exceed the threshold of deterministic radiation damage; therefore, fetal malformations or fetal loss are not to be expected; however, there is a low stochastic risk for the delayed occurrence of radiation-induced cancer both for the child and the mother that can be considered small in comparison to missed or delayed diagnoses after severe trauma. Intravenous, nonionic iodinated contrast agents are not contraindicated during pregnancy and should be administered whenever their use would also be considered appropriate in a nonpregnant patient; however, unnecessary scans and, if possible, multiple contrast agent phases should be avoided in order to reduce radiation. Magnetic resonance imaging (MRI) has a major role in the subacute setting and constitutes an excellent problem solver for specific questions, such as the evaluation of discoligamentous injuries of the spine. Its use is deemed acceptable at any stage of pregnancy when the required information is considered important for the management of further treatment. Due to potential teratogenic effects of MRI contrast media containing gadolinium on the fetus, including an increased likelihood of fetal loss, they should only be administered with great caution and under strictly defined indications.
Subject(s)
Magnetic Resonance Imaging , Radiology , Child , Contrast Media , Female , Fetus , Humans , Pregnancy , Tomography, X-Ray ComputedABSTRACT
INTRODUCTION: We aimed to evaluate whether PIRADS 3 lesions in multiparametric MRI (mpMRI) represent a significant risk of prostate cancer (PCa) in a real-world setting of different referring radiologic institutes. MATERIALS AND METHODS: Between May 2015 and October 2017, a total of 408 patients were referred to our clinic for MRI-ultrasound fusion targeted biopsy of the prostate (FusPbx) due to suspected prostate cancer. In all patients, preoperatively an mpMRI of the prostate was performed by altogether 62 different radiologic institutes. Prostate lesions were classified according to the PIRADS system. A PIRADS 3 lesion was diagnosed in 41 patients. FusPbx was performed transrectally using a Philips EPIQ 7 (Philips Medical Systems, Bothell, WA) scanner with plane wise fusion of ultrasound and MRI image data. In addition to FusPbx in each patient a randomized 12-core transrectal ultrasound guided biopsy (USPbx) was performed. RESULTS: Mean PSA Level was 9.5âng/ml (range: 1- 26âng/ml), mean patients age was 66.1 years (48.6- 80.4). In 11/41 patients (26.8%) prostate cancer was diagnosed by FusPbx of the PIRADS 3 lesion. In the target lesion PCa was classified as Gleason Score 3+3 in 5 patients, as 3+4 in 3, 4+3 in 1, 4+4 in 1 and 4+5 in 1 patient. In patients with negative FusPbx USPbx revealed PCa in another 7 patients (17.1%). In 5 of these GS 3+3 PCa was found, in another 2 patients GS 3+4 PCa. CONCLUSIONS: PIRADS 3 lesion indicates an equivocal likelihood of significant prostate cancer. In our series the overall PCa detection rate was 26.8% and 14.6% for clinically significant cancer in PIRADS 3 lesions. This evokes the question, if PIRADS 3 lesions could be surveilled only. The findings should be confirmed in a larger series.
Subject(s)
Magnetic Resonance Imaging/methods , Prostate/diagnostic imaging , Prostatic Neoplasms/diagnostic imaging , Aged , Aged, 80 and over , Humans , Image-Guided Biopsy/methods , Male , Middle Aged , Prostate/pathology , Prostatic Neoplasms/pathologyABSTRACT
BACKGROUND: The first method of choice for gallbladder alteration detection is the conventional ultrasound. Due to some imaging limitations, contrast-enhanced ultrasound (CEUS) has been widely used in the last years. CEUS is an additional modality that is able to depict microvessels flow and elucidate suspicious findings. OBJECTIVE: The aim of this retrospective mono-center analysis study is to evaluate the performance of CEUS in gallbladder diseases and compare it to cross-sectional imaging modalities and histopathological results as gold standard. METHODS: The retrospective study analysed 37 patients with gallbladder diseases between 2009 and 2017. All patients underwent CEUS examinations and additional cross-sectional imaging was also performed: CT imaging on 24 (64.9%) patients, MRI imaging on 18 (48.6%) patients, CT and MRI imaging on (28.7%). CEUS images were performed and interpreted by a single physician. RESULTS: CEUS imaging results of the gallbladder showed a sensitivity and specificity of 100%, a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 100%. CT imaging of the gallbladder showed a sensitivity of 100%, specificity of 75%, PPV of 100%, and NPV of 95%. MR imaging of the gallbladder showed a sensitivity of 100%, specificity of 93%, PPV of 75%, and NPV of 100%. CONCLUSION: Ultrasound imaging plays an essential role in the evaluation of gallbladder disease. Due to additional features of contrast-enhanced ultrasound, it is possible to differentiate gallbladder pathologic alterations by depicting its micro and macrocirculation and display important malignant features that recommends prompt management. Patients with contraindications to other cross-sectional imaging modalities benefit from this safe technique.
Subject(s)
Contrast Media/therapeutic use , Echocardiography/methods , Gallbladder Diseases/diagnostic imaging , Ultrasonography/methods , Adult , Aged , Aged, 80 and over , Female , Gallbladder Diseases/diagnosis , Gallbladder Diseases/pathology , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
BACKGROUND: Radiologic imaging, especially ultrasound has an important role in the assessment of gallbladder alteration. Contrast-enhanced ultrasound (CEUS) is an easy and fast imaging technique that overcomes the limitations of greyscale ultrasonography. It is a safe tool that can be used as an additional imaging modality in order to elucidate and differentiate gallbladder pathological findings. OBJECTIVE: The aim of this retrospective study analysis is to assess the diagnostic performance of CEUS in gallbladder alterations and compare the results to the histopathological findings. METHODS: A total of 17 patients between 2009 and 2017 with uncertain gallbladder appearance were retrospectively analysed. A single experienced physician with more than fifteen years' experience performed CEUS examinations by applying a second-generation blood pool agent (SonoVue®, Bracco, Milan, Italy). Archived images were interpreted by the same physician and compared to the histopathological findings. RESULTS: CEUS results, when correlated to the respectively pathologic findings, presented a sensitivity of 100%, a specificity of 100%, a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 100%. All patients were successfully examined without any adverse reaction. CONCLUSION: In conclusion, the excellent results in this study acknowledged that CEUS is a feasible alternative tool to differentiate gallbladder pathologic alterations.
Subject(s)
Contrast Media/therapeutic use , Gallbladder Diseases/diagnostic imaging , Gallbladder Diseases/diagnosis , Ultrasonography/methods , Adult , Aged , Aged, 80 and over , Female , Gallbladder Diseases/pathology , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
PURPOSE: Differences in resting energy expenditure (REE) between men and women mainly result from sex-related differences in lean body mass (LBM). So far, a little is known about whether REE and LBM are reflected by a distinct human metabolite profile. Therefore, we aimed to identify plasma and urine metabolite patterns that are associated with REE and LBM of healthy subjects. METHODS: We investigated 301 healthy male and female subjects (18-80 years) under standardized conditions in the cross-sectional KarMeN (Karlsruhe Metabolomics and Nutrition) study. REE was determined by indirect calorimetry and LBM by dual X-ray absorptiometry. Fasting blood and 24 h urine samples were analyzed by targeted and non-targeted metabolomics methods using GC × GC-MS, GC-MS, LC-MS, and NMR. Data were evaluated by predictive modeling of combined data using different machine learning algorithms, namely SVM, glmnet, and PLS. RESULTS: When evaluating data of men and women combined, we were able to predict REE and LBM with high accuracy (> 90%). This, however, was a clear effect of sex, which is supported by the high degree of overlap in identified important metabolites for LBM, REE, and sex, respectively. The applied machine learning algorithms did not reveal a metabolite pattern predictive of REE or LBM, when analyzing data for men and women, separately. CONCLUSIONS: We could not identify a sex independent predictive metabolite pattern for REE or LBM. REE and LBM have no impact on plasma and urine metabolite profiles in the KarMeN Study participants. Studies applying metabolomics in healthy humans need to consider sex specific data evaluation.
Subject(s)
Basal Metabolism/physiology , Body Composition/physiology , Metabolome/physiology , Absorptiometry, Photon , Adolescent , Adult , Aged , Aged, 80 and over , Cross-Sectional Studies , Female , Healthy Volunteers , Humans , Male , Middle Aged , Reference Values , Sex Factors , Young AdultABSTRACT
Alloying provides a means by which to tune a metal catalyst's electronic structure and thus tailor its performance; however, mean-field behaviour in metals imposes limits. To access unprecedented catalytic behaviour, materials must exhibit emergent properties that are not simply interpolations of the constituent components' properties. Here we show an emergent electronic structure in single-atom alloys, whereby weak wavefunction mixing between minority and majority elements results in a free-atom-like electronic structure on the minority element. This unusual electronic structure alters the minority element's adsorption properties such that the bonding with adsorbates resembles the bonding in molecular metal complexes. We demonstrate this phenomenon with AgCu alloys, dilute in Cu, where the Cu d states are nearly unperturbed from their free-atom state. In situ electron spectroscopy demonstrates that this unusual electronic structure persists in reaction conditions and exhibits a 0.1 eV smaller activation barrier than bulk Cu in methanol reforming. Theory predicts that several other dilute alloys exhibit this phenomenon, which offers a design approach that may lead to alloys with unprecedented catalytic properties.
ABSTRACT
BACKGROUND: Contrast-enhanced ultrasound (CEUS) has been used as an additional imaging technique to conventional ultrasound in order to clarify gallbladder findings, CEUS is easy and fast to perform, overcomes the limitations of gray-scale ultrasonography and is a safe tool. OBJECTIVE: The aim of this retrospective mono-center analysis study is to evaluate the diagnostic performance of CEUS in the assessment of gallbladder disease by comparing its results with additional CT findings. METHODS: A total of 24 patients between 2009 and 2017 with unclear gallbladder appearance were retrospectively analysed. The contrast agent administered was a second-generation blood pool agent (SonoVue®, Bracco, Milan, Italy). Examinations were performed and interpreted by a single experienced radiologist with more than fifteen years' experience. RESULTS: 24 patients were successfully examined without any adverse reaction. CEUS presented a sensitivity of 75%, a specificity of 100.0%, a positive predictive value of 100.0% and a negative predictive value of 95%. CONCLUSIONS: In conclusion, the excellent results in this study acknowledged that CEUS is a feasible alternative tool to differentiate gallbladder pathologic alterations.
Subject(s)
Contrast Media/therapeutic use , Gallbladder Diseases/diagnostic imaging , Ultrasonography/methods , Adult , Aged , Aged, 80 and over , Female , Gallbladder Diseases/pathology , Humans , Male , Middle Aged , Retrospective StudiesABSTRACT
CO adsorption on the polar (1[combining macron]1[combining macron]1[combining macron]) surface of the intermetallic compound GaPd is examined within ab initio methods using an all-electron full-potential electronic structure approach. Comparison between the PW-LDA, GGA-PBE, GGA-RPBE, GGA-revPBE, and hybrid HSE06 functionals is considered through bulk, clean surface and CO adsorption calculations. The choice of the functional is found to have a strong influence in the description of single CO adsorption on the surface model proposed in literature. As expected from the so called "CO adsorption puzzle", differences in the obtained results demonstrate that classic LDA and PBE functionals can only partially describe the complex CO adsorption bonding scenario on a surface containing transition metal elements (in this case Pd atoms), where the energies of the substrate-adsorbate electronic states are shifted, yielding important differences in the absolute values of the adsorption energies, vibrational frequencies and surface-adsorbate interaction. So far the hybrid functional HSE06 correctly retrieves all the tendencies observed experimentally as confirmed by comparing our first-principles results to experimental findings.
ABSTRACT
The oxidation of copper catalysts during ethylene epoxidation was characterized using in situ photoemission spectroscopy and electron microscopy. Gas chromatography, proton-transfer reaction mass spectrometry and electron-ionization mass spectrometry were used to characterize the catalytic properties of the oxidized copper. We find that copper corrodes during epoxidation in a 1 : 1 mixture of oxygen and ethylene. The catalyst corrosion passes through several stages, beginning with the formation of an O-terminated surface, followed by the formation of Cu2O scale and eventually a CuO scale. The oxidized catalyst exhibits measurable activity for ethylene epoxidation, but with a low selectivity of <3%. Tests on pure Cu2O and CuO powders confirm that the oxides intrinsically exhibit partial-oxidation activity. Cu2O was found to form acetaldehyde and ethylene epoxide in roughly equal amounts (1.0% and 1.2% respectively), while CuO was found to form much less ethyl aldehyde than ethylene epoxide (0.1% and 1.0%, respectively). Metallic copper catalysts were examined in extreme dilute-O2 epoxidation conditions to try and keep the catalyst from oxidizing during the reaction. It was found that in feed of 1 part O2 to 2500 parts C2H4 (PO2 = 1.2 × 10(-4) mbar) the copper surface becomes O-terminated. The O-terminated surface was found to exhibit partial-oxidation selectivity similar to that of Cu2O. With increasing O2 concentration (>8/2500) Cu2O forms and eventually covers the surface.
ABSTRACT
The intermetallic compound InPd (CsCl type of crystal structure with a broad compositional range) is considered as a candidate catalyst for the steam reforming of methanol. Single crystals of this phase have been grown to study the structure of its three low-index surfaces under ultra-high vacuum conditions, using low energy electron diffraction (LEED), X-ray photoemission spectroscopy (XPS), and scanning tunneling microscopy (STM). During surface preparation, preferential sputtering leads to a depletion of In within the top few layers for all three surfaces. The near-surface regions remain slightly Pd-rich until annealing to â¼580 K. A transition occurs between 580 and 660 K where In segregates towards the surface and the near-surface regions become slightly In-rich above â¼660 K. This transition is accompanied by a sharpening of LEED patterns and formation of flat step-terrace morphology, as observed by STM. Several superstructures have been identified for the different surfaces associated with this process. Annealing to higher temperatures (≥750 K) leads to faceting via thermal etching as shown for the (110) surface, with a bulk In composition close to the In-rich limit of the existence domain of the cubic phase. The Pd-rich InPd(111) is found to be consistent with a Pd-terminated bulk truncation model as shown by dynamical LEED analysis while, after annealing at higher temperature, the In-rich InPd(111) is consistent with an In-terminated bulk truncation, in agreement with density functional theory (DFT) calculations of the relative surface energies. More complex surface structures are observed for the (100) surface. Additionally, individual grains of a polycrystalline sample are characterized by micro-spot XPS and LEED as well as low-energy electron microscopy. Results from both individual grains and "global" measurements are interpreted based on comparison to our single crystals findings, DFT calculations and previous literature.
ABSTRACT
OBJECTIVES: The aim of the study was to determine whether automated quantification of pulmonary perfused blood volume (PBV) in dual-energy computed tomography pulmonary angiography (DE-CTPA) can be used to assess the severity of chronic thromboembolic pulmonary hypertension (CTEPH). METHODS: Automated quantification of PBV was performed in 25 consecutive CTEPH patients undergoing DE-CTPA. PBV values were correlated with cardiac index and pulmonary vascular resistance quantified by right heart catheterization and walking distance in the 6-minute walk test using Pearson's correlation coefficient and multivariate linear regression analysis to control for age and gender. RESULTS: DE-CTPA derived PBV values inversely correlated with systolic (râ=â-0.64, pâ=â0.001) and mean (râ=â-0.57, pâ=â0.004) pulmonary arterial pressure. There was a trend for PBV values to inversely correlate with pulmonary vascular resistance (râ=â-0.20, pâ=â0.35). No significant correlation was found between PBV values and cardiac index or 6-minute walking distance. These correlations were confirmed to be independent of age and gender on multivariate linear regression analysis. CONCLUSION: DE-CTPA can be used for an automated quantification of pulmonary PBV in chronic thromboembolic pulmonary hypertension. PBV values correlate inversely with systolic and mean pulmonary arterial pressure and can thus be used to estimate the severity of pulmonary hypertension in these patients. Citation Format: â¢âMeinel FG, Graef A, Thierfelder KM etâal. Automated Quantification of Pulmonary Perfused Blood Volume by Dual-Energy CTPA in Chronic Thromboembolic Pulmonary Hypertension. Fortschr Röntgenstr 2014; 186: 151â-â156.
Subject(s)
Hypertension, Pulmonary/diagnostic imaging , Hypertension, Pulmonary/physiopathology , Pulmonary Embolism/diagnostic imaging , Pulmonary Embolism/physiopathology , Radiographic Image Interpretation, Computer-Assisted/methods , Radiography, Dual-Energy Scanned Projection/methods , Tomography, X-Ray Computed/methods , Adult , Aged , Aged, 80 and over , Algorithms , Angiography , Blood Volume , Blood Volume Determination/methods , Chronic Disease , Female , Humans , Hypertension, Pulmonary/etiology , Male , Middle Aged , Pulmonary Embolism/complications , Radiographic Image Enhancement/methods , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
BACKGROUND: Given that micelles of lipids are colloids, the hypothesis was generated that the rapid administration of large volumes of soybean oil micelles would be an effective perfusion fluid. We also hypothesized that oxygen loading would be enhanced due to the greater solubility of oxygen in lipids compared to water. METHODS: A 100% lethal mouse model of blood loss was used to compare the ability of soybean oil micelles to that of Ringer's lactate, blood and other fluids, with respect to raising and maintaining the blood pressure for one hour. Oxygen on- and off-loading of various concentrations of soybean oil micelles was determined using mass spectroscopy. Nitric oxide uptake by micelles was also determined in a similar fashion. RESULTS: A 20% soybean oil emulsion was superior to Ringer's lactate in raising and maintaining blood pressure. A 20% soybean oil emulsion with 5% albumin added was superior to shed blood as well as solutions comprised of 5% albumin added to either normal saline or Ringer's lactate. There was a linear relationship between oxygen content and micelle concentration between 10% and 30%. Off-loading of oxygen from the micelles was nearly as fast as off-loading from water. Nitric oxide also loaded preferentially onto soybean oil micelles. CONCLUSIONS: (1) Soybean oil emulsions were superior to other fluids in restoring and maintaining the blood pressure; (2) oxygen-carrying ability of soybean oil micelles exceeds that of water and follows Henry's law between 10% and 30% w/v oil content; (3) nitric oxide was carried by the micelles; (4) animals receiving soybean oil micelles did not exhibit fat embolization; (5) colloids comprised of soybean oil-containing micelles may be used to replace blood loss and may be used to deliver oxygen and other potentially therapeutic gases such as nitric oxide to tissues.
Subject(s)
Fat Emulsions, Intravenous , Micelles , Oxygen/blood , Shock, Hemorrhagic/blood , Shock, Hemorrhagic/drug therapy , Soybean Oil , Animals , Blood Pressure/drug effects , Disease Models, Animal , Fat Emulsions, Intravenous/chemistry , Fat Emulsions, Intravenous/pharmacokinetics , Fat Emulsions, Intravenous/pharmacology , Mice , Nitric Oxide/blood , Shock, Hemorrhagic/physiopathology , Soybean Oil/chemistry , Soybean Oil/pharmacokinetics , Soybean Oil/pharmacologyABSTRACT
The isotopic phonon effects in LaB(6) are investigated on the Raman spectra of a series of high-quality single crystals with systematically varied contents of (10)B and (11)B isotopes. A detailed group theoretical analysis enlightens the correlation between distortions of the B(6) octahedra and the splitting or broadening of phonon modes. It is evident that LaB(6) does not have cubic symmetry as assumed so far. A further symmetry reduction of the B(6) octahedra occurs in isotopically mixed crystals. There, the distribution of isotopes is not random as commonly assumed; the probability of associating equal isotopes increases with their mass decreasing.
ABSTRACT
Replacing noble metals in heterogeneous catalysts by low-cost substitutes has driven scientific and industrial research for more than 100 years. Cheap and ubiquitous iron is especially desirable, because it does not bear potential health risks like, for example, nickel. To purify the ethylene feed for the production of polyethylene, the semi-hydrogenation of acetylene is applied (80 × 10(6) tons per annum; refs 1-3). The presence of small and separated transition-metal atom ensembles (so-called site-isolation), and the suppression of hydride formation are beneficial for the catalytic performance. Iron catalysts necessitate at least 50 bar and 100 °C for the hydrogenation of unsaturated C-C bonds, showing only limited selectivity towards semi-hydrogenation. Recent innovation in catalytic semi-hydrogenation is based on computational screening of substitutional alloys to identify promising metal combinations using scaling functions and the experimental realization of the site-isolation concept employing structurally well-ordered and in situ stable intermetallic compounds of Ga with Pd (refs 15-19). The stability enables a knowledge-based development by assigning the observed catalytic properties to the crystal and electronic structures of the intermetallic compounds. Following this approach, we identified the low-cost and environmentally benign intermetallic compound Al(13)Fe(4) as an active and selective semi-hydrogenation catalyst. This knowledge-based development might prove applicable to a wide range of heterogeneously catalysed reactions.
ABSTRACT
On the basis of the spectra of IR- and Raman-active phonons, the isotopic phonon effects in ß-rhombohedral boron are analysed for polycrystalline (10)B- and (11)B-enriched samples of different origin and high-purity (nat)B single crystals. Intra- and inter-icosahedral B-B vibrations are harmonic, hence meeting the virtual crystal approximation (VCA) requirements. Deviations from the phonon shift expected according to the VCA are attributed to the anharmonic share of the lattice vibrations. In the case of icosahedral vibrations, the agreement with calculations on α-rhombohedral boron by Shirai and Katayama-Yoshida is quite satisfactory. Phonon shifts due to isotopic disorder in (nat)B are separated and determined. Some phonon frequencies are sensitive to impurities. The isotopic phonon effects yield valuable specific information on the nature of the different phonon modes. The occupation of regular boron sites by isotopes deviates significantly from the random distribution.
ABSTRACT
The PdGa intermetallic compound is a highly selective and stable heterogeneous hydrogenation catalyst for the semi-hydrogenation of acetylene. We have studied single crystals of PdGa grown by the Czochralski technique. The (69)Ga electric-field-gradient (EFG) tensor was determined by means of NMR spectroscopy, giving experimental confirmation of both the recently refined structural model of PdGa and the theoretically predicted Pd-Ga covalent bonding scheme. The hydrogenation experiment has detected no hydrogen uptake in the PdGa, thus preventing in situ hydride formation that leads to a reduction of the catalytic selectivity. We have also determined bulk physical properties (the magnetic susceptibility, the electrical resistivity, the thermoelectric power, the Hall coefficient, the thermal conductivity and the specific heat) of single-crystalline PdGa. The results show that PdGa is a diamagnet with metallic electrical resistivity and moderately high thermal conductivity. The thermoelectric power is negative with complicated temperature dependence, whereas the Hall coefficient is positive and temperature-dependent, indicating complexity of the Fermi surface. Partial fulfillment of the NMR Korringa relation reveals that the charge carriers are weakly correlated. Specific heat measurements show that the density of electronic states (DOS) at the Fermi energy of PdGa is reduced to 15% of the DOS of the elemental Pd metal.
ABSTRACT
The Raman spectra of numerous dodecaborides have been measured on high-quality single crystals at ambient conditions with high spectral resolution and signal-to-noise ratio. Besides the strong Raman-active modes, numerous Raman-inactive modes occur in the spectra, indicating distortions of the structures. Ab initio calculation of the phonon spectra on ZrB(12) excellently agrees with the experimental results. Force constants are theoretically calculated and force parameters are estimated from the Raman frequencies. The influence of the surface range on the Raman spectra is evident. The different isotopic effects (virtual crystal approximation, the polarization effect and the effect of isotopic disorder) on the phonon frequencies are determined, separated and discussed.
ABSTRACT
Humic acids (HA) have a high binding capacity towards traces of toxic metal cations, thus affecting their transport in aquatic systems. Eu(III)-HA aggregates are studied by synchrotron-based scanning transmission X-ray microscopy (STXM) at the carbon K-edge and laser scanning luminescence microscopy (LSLM) at the (5)D(0) --> (7)F(1,2) fluorescence emission lines. Both methods provide the necessary spatial resolution in the sub-micrometre range to resolve characteristic aggregate morphologies: optically dense zones embedded in a matrix of less dense material in STXM images correspond to areas with increased Eu(III) luminescence yield in the LSLM micrographs. In the C 1s-NEXAFS of metal-loaded polyacrylic acid (PAA), used as a HA model compound, a distinct complexation effect is identified. This effect is similar to trends observed in the dense fraction of HA/metal cation aggregates. The strongest complexation effect is observed for the Zr(IV)-HA/PAA system. This effect is confirmed by quantum chemical calculations performed at the ab initio level for model complexes with different metal centres and complex geometries. Without the high spatial resolution of STXM and LSLM and without the combination of molecular modelling with experimental results, the different zones indicating a ;pseudo'-phase separation into strong complexing domains and weaker complexing domains of HA would never have been identified. This type of strategy can be used to study metal interaction with other organic material.
Subject(s)
Europium/chemistry , Humic Substances/analysis , Microscopy, Confocal/methods , Cations/chemistry , Luminescence , Microscopy/methods , Quantum TheoryABSTRACT
The discrepancy between Raman spectra of boron carbide obtained by Fourier transform Raman and conventional Raman spectrometry is systematically investigated. While at photon energies below the exciton energy (1.560 eV), Raman scattering of bulk phonons of boron carbide occurs, photon energies exceeding the fundamental absorption edge (2.09 eV) evoke additional patterns, which may essentially be attributed to luminescence or to the excitation of Raman-active processes in the surface region. The reason for this is the very high fundamental absorption in boron carbide inducing a very small penetration depth of the exciting laser radiation. Raman excitations essentially restricted to the boron carbide surface region yield spectra which considerably differ from bulk phonon ones, thus indicating structural modifications.
ABSTRACT
BACKGROUND AND PURPOSE: Glucocorticoid-induced osteoporosis (GIO) is the leading cause of secondary osteoporosis. Clinical evidence suggests a role for genistein aglycone in the treatment of post-menopausal osteopenia although proof of efficacy in comparison with currently available treatments is still lacking. To clarify this issue, we investigated the effects of genistein on bone compared with alendronate in experimental GIO. EXPERIMENTAL APPROACH: A total of 28 female Sprague-Dawley rats were used. GIO was induced by daily injections of methylprednisolone (MP; 30 mg x kg(-1) s.c.) for 60 days. Sham GIO animals (Sham-MP) were injected daily with the MP vehicle. At the end of the osteoporosis development period, MP rats were randomized to receive: vehicle (n= 7), genistein aglycone (5 mg x kg(-1) s.c.; n= 7) or alendronate (0.03 mg x kg(-1) s.c.; n= 7). Treatment lasted 60 days. Sham-MP animals were treated with vehicle for an additional 60 days. At the beginning and at the end of treatments, animals were examined for bone mineral density and bone mineral content. Bone-alkaline phosphatase and carboxy-terminal collagen cross links were determined; femurs were removed and tested for breaking strength and histology. KEY RESULTS: Genistein aglycone showed a greater increase in bone mineral density, bone mineral content and in breaking strength than alendronate and significantly increased bone-alkaline phosphatase (bone formation marker), reduced carboxy-terminal collagen cross links (bone resorption marker), compared with alendronate. Both treatments improved bone histology and the histological score. CONCLUSION AND IMPLICATIONS: The results strongly suggest that the genistein aglycone might be an alternative therapy for the management of secondary osteoporosis.