4,321 research outputs found

    Scedosporium prolificans Septic Arthritis

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    Scedosporium prolificans is an emerging fungal pathogen that can cause significant morbidity, and even mortality, in both immunocompromised and immunocompetent patients. Approximately 10% of patients affected by this rare fungal pathogen present with septic osteomyelitis or arthritis. Overall, the rate of mortality is close to 50%, and several patients with orthopedic infections have required amputations.1 Our patient is a 59-year-old woman, with a history of rheumatoid arthritis requiring immunosuppressants, who presented with a 5-month history of right wrist pain and swelling. She described an oscillating course of swelling, erythema, and pain involving the dorsal aspect of her wrist that did not show sustained response to antibiotics or a radiocarpal joint steroid injection given by other providers. On initial examination, she was afebrile with dorsal wrist swelling. There was no erythema, but wrist mobility was limited. She had tenderness throughout the wrist, but no fluctuance or drainage. All initial laboratory work was normal. Right wrist X-ray showed severe osteopenia with some mild evidence of cortical erosion. Despite the normal laboratory values, her presenting findings of swelling, radiographic erosions, and immunocompromised state prompted concern for atypical septic arthritis. The patient subsequently underwent wrist exploration for tissue and culture harvest. In addition to extensive wrist synovectomy, the proximal pole of the scaphoid, lunate, triquetrum, capitate, hamate, and metacarpal bases all showed evidence of necrosis that required debridement. One week later, her fluid aspirate and bone cultures unexpectedly grew an unidentified fungal species, and she was taken back to the operating room for further debridement and placement of a voriconazole-impregnated cement spacer. The culture grew pan-resistant Scedosporium prolificans, and based on recommendations from Rheumatology and Infectious Disease, the patient was started on a 6-week course of intravenous micafungin, and immunosuppressive medications were stopped. She returned to the operating room for debridement and serial treatments with polyhexamethylene biguanide (PHMB) irrigation until intraoperative tissue cultures showed no growth. PHMB is an antiseptic medication that has been described as a local adjunct to the treatment of resistant fungal infections.2–4 After successful eradication of her infection, she underwent wrist reconstruction and fusion with a double-barrel free fibula osteocutaneous flap. She is now 18 months out from her reconstruction, has healed uneventfully, and has a functional, painless upper extremity

    Theory of Unconventional Spin Density Wave: A Possible Mechanism of the Micromagnetism in U-based Heavy Fermion Compounds

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    We propose a novel spin density wave (SDW) state as a possible mechanism of the anomalous antiferromagnetism, so-called the micromagnetism, in URu_2Si_2 below 17.5[K]. In this new SDW, the electron-hole pair amplitude changes its sign in the momentum space as in the case of the unconventional superconductivity. It is shown that this state can be realized in an extended Hubbard model within the mean field theory. We also examine some characteristic properties of this SDW to compare with the experimental results. All these properties well explain the unsolved problem of the micromagnetism.Comment: REVTeX v3.1, 4 pages, 5 figure

    Resonant Inelastic X-Ray Scattering from Valence Excitations in Insulating Copper-Oxides

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    We report resonant inelastic x-ray measurements of insulating La2_2CuO4_4 and Sr2_2CuO2_2Cl2_2 taken with the incident energy tuned near the Cu K absorption edge. We show that the spectra are well described in a shakeup picture in 3rd order perturbation theory which exhibits both incoming and outgoing resonances, and demonstrate how to extract a spectral function from the raw data. We conclude by showing {\bf q}-dependent measurements of the charge transfer gap.Comment: minor notational changes, discussion of anderson impurity model fixed, references added; accepted by PR

    X-ray Scattering Study of the spin-Peierls transition and soft phonon behavior in TiOCl

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    We have studied the S=1/2 quasi-one-dimensional antiferromagnet TiOCl using single crystal x-ray diffraction and inelastic x-ray scattering techniques. The Ti ions form staggered spin chains which dimerize below Tc1 = 66 K and have an incommensurate lattice distortion between Tc1 and Tc2 = 92 K. Based on our measurements of the intensities, wave vectors, and harmonics of the incommensurate superlattice peaks, we construct a model for the incommensurate modulation. The results are in good agreement with a soliton lattice model, though some quantitative discrepancies exist near Tc2. The behavior of the phonons has been studied using inelastic x-ray scattering with ~2 meV energy resolution. For the first time, a zone boundary phonon which softens at the spin-Peierls temperature Tsp has been observed. Our results show reasonably good quantitative agreement with the Cross-Fisher theory for the phonon dynamics at wave vectors near the zone boundary and temperatures near Tsp. However, not all aspects of the data can be described, such as the strong overdamping of the soft mode above Tsp. Overall, our results show that TiOCl is a good realization of a spin-Peierls system, where the phonon softening allows us to identify the transition temperature as Tsp=Tc2=92 KComment: 14 pages, 14 figure

    MR diffusion changes in the perimeter of the lateral ventricles demonstrate periventricular injury in post-hemorrhagic hydrocephalus of prematurity

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    OBJECTIVES: Injury to the preterm lateral ventricular perimeter (LVP), which contains the neural stem cells responsible for brain development, may contribute to the neurological sequelae of intraventricular hemorrhage (IVH) and post-hemorrhagic hydrocephalus of prematurity (PHH). This study utilizes diffusion MRI (dMRI) to characterize the microstructural effects of IVH/PHH on the LVP and segmented frontal-occipital horn perimeters (FOHP). STUDY DESIGN: Prospective study of 56 full-term infants, 72 very preterm infants without brain injury (VPT), 17 VPT infants with high-grade IVH without hydrocephalus (HG-IVH), and 13 VPT infants with PHH who underwent dMRI at term equivalent. LVP and FOHP dMRI measures and ventricular size-dMRI correlations were assessed. RESULTS: In the LVP, PHH had consistently lower FA and higher MD and RD than FT and VPT (p\u3c.050). However, while PHH FA was lower, and PHH RD was higher than their respective HG-IVH measures (p\u3c.050), the MD and AD values did not differ. In the FOHP, PHH infants had lower FA and higher RD than FT and VPT (p\u3c.010), and a lower FA than the HG-IVH group (p\u3c.001). While the magnitude of AD in both the LVP and FOHP were consistently less in the PHH group on pairwise comparisons to the other groups, the differences were not significant (p\u3e.050). Ventricular size correlated negatively with FA, and positively with MD and RD (p\u3c.001) in both the LVP and FOHP. In the PHH group, FA was lower in the FOHP than in the LVP, which was contrary to the observed findings in the healthy infants (p\u3c.001). Nevertheless, there were no regional differences in AD, MD, and RD in the PHH group. CONCLUSION: HG-IVH and PHH results in aberrant LVP/FOHP microstructure, with prominent abnormalities among the PHH group, most notably in the FOHP. Larger ventricular size was associated with greater magnitude of abnormality. LVP/FOHP dMRI measures may provide valuable biomarkers for future studies directed at improving the management and neurological outcomes of IVH/PHH

    Achieving consensus on minimum data items (including core outcome domains) for a longitudinal observational cohort study in rheumatoid arthritis

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    Objectives: To obtain consensus on minimum data items for an observational cohort study in rheumatoid arthritis (RA) in the UK and to make available the process for similar studies and other rheumatic conditions. Methods: Individuals with a diverse range of expertise and backgrounds were invited to participate in a process to propose a minimal core dataset (MCD) for research studies, commissioned by Arthritis Research UK as part of the larger INBANK project. The group included patients and representatives from clinical and academic rheumatology, outcomes science, stratified medicine, health economics, national professional and academic bodies/ committees. A process was devised based on Outcome Measures in Rheumatology Clinical Trials (OMERACT) principles to review aims/objectives, definition of scope, identification of important research questions, and selection of key domains. Results: Following the initial multi-stakeholder meeting, subsequent teleconferences and email communications, consensus was obtained on: 1. Most important and relevant research questions; 2. Agreement on how the OMERACT Core Areas (life impact, pathophysiological manifestations, resource use and death) could form the basis of a MCD; 3. Consensus on 22 items for inclusion into a MCD. Workshops were undertaken for two essential items which required further exploration: work/social participation and co-morbidity. Conclusions: Consensus for proposed minimal data items for long-term observational cohort studies of RA in the UK posed novel challenges and opportunities, and was largely successful. Further work is needed to select instruments for two important items and to achieve compatibility with other UK national initiatives, and more widely across Europe

    Congenital tumors: imaging when life just begins

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    BACKGROUND: The technical developments of imaging methods over the last 2 decades are changing our knowledge of perinatal oncology. Fetal ultrasound is usually the first imaging method used and thus constitutes the reference prenatal study, but MRI seems to be an excellent complementary method for evaluating the fetus. The widespread use of both techniques has increased the diagnosis rates of congenital tumors. During pregnancy and after birth, an accurate knowledge of the possibilities and limits of the different imaging techniques available would improve the information obtainable, thus helping the medical team to make the most appropriate decisions about therapy and to inform the family about the prognosis. CONCLUSION: In this review article, we describe the main congenital neoplasms, their prognosis and their imaging characteristics with the different pre- and postnatal imaging methods available

    Identification of Non-unitary triplet pairing in a heavy Fermion superconductor UPt_3

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    A NMR experiment recently done by Tou et al. on a heavy Fermion superconductor UPt3_3 is interpreted in terms of a non-unitary spin-triplet pairing state which we have been advocating. The proposed state successfully explains various aspects of the seemingly complicated Knight shift behaviors probed for major orientations, including a remarkable d-vector rotation under weak fields. This entitles UPt3_3 as the first example that a charged many body system forms a spin-triplet odd-par ity pairing at low temperatures and demonstrates unambiguously that the putative spin-orbit coupling in UPt3_3 is weak.Comment: 4 pages, 2 eps figures, to be published in J. Phys. Soc. Jpn. 67 (1998) No.
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