929 resultados para Electron paramagnetic resonance imaging (EPRI)


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There is substantial controversy in literature about human dermatomes. We studied L4, L5, and S1 inferior limb dermatomes by comparing clinical signs and symptoms with conduction studies, electromyographical data, neurosurgical findings, and imaging data from computerized tomography (CT) or magnetic resonance imaging (MRI). After analyzing 60 patients, we concluded that L4 is probably located in the medial aspect of the leg, L5 in the lateral aspect of the leg and foot dorsus, and S1 in the posterior aspect of the backside, tight, leg and plantar foot skin. This is the first time that these human dermatomes have been evaluated by combined analysis of clinical, electromyographical, neurosurgical, and imaging data.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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From Electron Spin Resonance (ESR) data in pressed pellets of BF4 - doped Poly(3-methylthiophene) (P3MT) we obtained simultaneously the paramagnetic susceptibility and. the microwave conductivity. We observed a transition from a high-temperature insulator state to a room-temperature metallic state. Around 240K. evidence of a Peierls transition is observed, but if the sample is slowly cooled, this transition is partially suppressed. DC conductivity data taken with the sample quenched to 79 K show a non-linear I-V response for very small electric fields, suggesting depinning of Charge-Density Wave (CDW). The data for heating and cooling the system above room temperature, indicate the formation of bipolarons.

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Nowadays, the research for new and better antimicrobial compounds is an important field due to the increase of immunocompromised patients, the use of invasive medical procedures and extensive surgeries, among others, that can affect the incidence of infections. Another big problem associated is the occurrence of drug-resistant microbial strains that impels a ceaseless search for new antimicrobial agents. In this context, a series of heterocyclic- sulfonamide complexes with Co(II) was synthesized and characterized with the aim of obtaining new antimicrobial compounds. The structural characterization was performed using different spectroscopic methods (UV-Vis, IR, and EPR). In spite of the fact that the general stoichiometry for all the complexes was Co(sulfonamide)2·nH2O, the coordination atoms were different depending on the coordinated sulfonamide. The crystal structure of [Co(sulfamethoxazole)2(H2O)2]·H 2O was obtained by X-ray diffraction showing that Co(II) is in a slightly tetragonal distorted octahedron where sulfamethoxazole molecules act as a head-to-tail bridges between two cobalt atoms, forming polymeric chains. Besides, the activity against Mycobacterium tuberculosis, one of the responsible for tuberculosis, and the cytotoxicity on J774A.1 macrophage cells were evaluated. © 2012 Elsevier B.V. All rights reserved.

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Antimicrobial peptides (AMPs) isolated from several organisms have been receiving much attention due to some specific features that allow them to interact with, bind to, and disrupt cell membranes. The aim of this paper was to study the interactions between a membrane mimetic and the cationic AMP Ctx(Ile21)-Ha as well as analogues containing the paramagnetic amino acid 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) incorporated at residue positions n = 0, 2, and 13. Circular dichroism studies showed that the peptides, except for [TOAC13]Ctx(Ile21)-Ha, are unstructured in aqueous solution but acquire different amounts of α-helical secondary structure in the presence of trifluorethanol and lysophosphocholine micelles. Fluorescence experiments indicated that all peptides were able to interact with LPC micelles. In addition, Ctx(Ile21)-Ha and [TOAC13]Ctx(Ile21)-Ha peptides presented similar water accessibility for the Trp residue located near the N-terminal sequence. Electron spin resonance experiments showed two spectral components for [TOAC0]Ctx(Ile21)-Ha, which are most likely due to two membrane-bound peptide conformations. In contrast, TOAC2 and TOAC13 derivatives presented a single spectral component corresponding to a strong immobilization of the probe. Thus, our findings allowed the description of the peptide topology in the membrane mimetic, where the N-terminal region is in dynamic equilibrium between an ordered, membrane-bound conformation and a disordered, mobile conformation; position 2 is most likely situated in the lipid polar head group region, and residue 13 is fully inserted into the hydrophobic core of the membrane. © 2013 Vicente et al.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Acute spinal cord trauma is a common injury that occurs frequently in small animals. In order to acertain a prognosis of the lesion generated in the spinal cord, it is necessary to perform a complete neurological and physical examination, aided by complementary images. Magnetic resonance imaging may be advantageous over other types of images, because it can determine with greater definition the structural damage to the nervous tissue. The objective of this report was to demonstrate the contribution of magnetic resonance imaging in a case of acute spinal cord trauma in a dog.

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The idiopathic dilated cardiomyopathy (IDC) is one of the major public health problems in the western world. Patients with IDC in functional class IV (New York Health Association - NYHA), even after therapeutic optimization, have high mortality. Stem cell therapy has emerged as a potential therapeutic option for cell death-related heart diseases and several positive effects were assigned to cell therapy in cardiomyopathy. The aim of this study was identify short-term result of cell transplantation in idiopathic dilated cardiomyopathy patients (IDC) who were treated by transplantation of autologous bone marrow mononuclear cells (BMMC). Intracoronary injections of autologous BMMC were performed in eight patients with severe ventricle dysfunction (mean of left ventricle ejection fraction – LEVF=20.03%), cardiac mass muscle around 156.2 g and NYHA between III and IV grades, other 8 IDC patients received placebo. The IDCs were followed - up for one and two years, by magnetic resonance imaging (MRI). The results after one year showed significant improvement in LVEF (mean=181.4) and muscle mass increasing (mean=181.4 g), after two years the LVEF continued improving, reaching a mean of 32.69% and the cardiac muscle mass kept stable (mean=179.4 g). Excepted for one patient, all the other had improvement in the NYHA functional class. The placebo group did not show any improvement. We believe that BMMC implant may be a beneficial therapeutic option for IDC patients.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Background: To establish the best methodology for diagnosis and management of patients with solid and complex renal masses by comparing the costs and benefits of different imaging methods and to improve differential diagnosis of these benign and malignant lesions, particularly by investigating tumour calcifications. Methods: We performed a prospective study on 31 patients with solid or complex masses by submitting them to Abdominal Ultrasonography (US), Doppler Ultrasonography of the renal mass (US Dop), Computed Tomography (CT), and Magnetic Resonance Imaging (MRI). Results: We found 28 patients with malignant and three with benign masses. Of the 28 malignant, 17 showed calcifications at CT; 16 central and one was of the pure peripheral curvilinear type (egg shell). Excretory Urography (IVP) had a significantly lower detection rate for central calcifications than both US and CT. Benign and malignant masses appeared as described in literature, with US, CT and MRI showing high sensitivity and specificity in renal tumor diagnosis. The exception was US Dop where we obtained lower sensitivity for the characterization of malignant tumor flow. Conclusions: In this series we were surprised to find that CT revealed central calcifications in 51.6% of patients, all with malignant lesions, while, literature reports a frequency of calcification in renal cell carcinoma between 8 and 22%, in studies using abdominal films and EU (IVP). This finding is of great importance when we consider that these calcifications occur particularly in malignant neoplasms. As a result of comparing these different imaging methods we have developed a better methodology for renal tumor investigation.

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The Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence has been used in many applications of magnetic resonance imaging (MRI) and low-resolution NMR (LRNMR) spectroscopy. Recently. CPMG was used in online LRNMR measurements that use long RF pulse trains, causing an increase in probe temperature and, therefore, tuning and matching maladjustments. To minimize this problem, the use of a low-power CPMG sequence based on low refocusing pulse flip angles (LRFA) was studied experimentally and theoretically. This approach has been used in several MRI protocols to reduce incident RF power and meet the specific absorption rate. The results for CPMG with LRFA of 3 pi/4 (CPMG(135)), pi/2 (CPMG(90)) and pi/4 (CPMG(45)) were compared with conventional CPMG with refocusing pi pulses. For a homogeneous field, with linewidth equal to Delta nu = 15 Hz, the refocusing flip angles can be as low as pi/4 to obtain the transverse relaxation time (T(2)) value with errors below 5%. For a less homogeneous magnetic field. Delta nu = 100 Hz, the choice of the LRFA has to take into account the reduction in the intensity of the CPMG signal and the increase in the time constant of the CPMG decay that also becomes dependent on longitudinal relaxation time (T(1)). We have compared the T(2) values measured by conventional CPMG and CPMG(90) for 30 oilseed species, and a good correlation coefficient, r = 0.98, was obtained. Therefore, for oilseeds, the T(2) measurements performed with pi/2 refocusing pulses (CPMG(90)), with the same pulse width of conventional CPMG, use only 25% of the RF power. This reduces the heating problem in the probe and reduces the power deposition in the samples. (C) 2011 Elsevier B.V. All rights reserved.