Time-frequency filtering of MEG signals with matching pursuit.

Time-frequency signal analysis based on various decomposition techniques is widely used in biomedical applications. Matching Pursuit is a new adaptive approach for time-frequency decomposition of such biomedical signals. Its advantage is that it creates a concise signal approximation with the help of a small set of Gabor atoms chosen iteratively from a large and redundant set. In this paper, the usage of Matching Pursuit for time-frequency filtering of biomagnetic signals is proposed. The technique was validated on artificial signals and its performance was tested for varying signal-to-noise ratios using both simulated and real MEG somatic evoked magnetic field data.     

Exposure of murine cells to pulsed electromagnetic fields rapidly activates the mTOR signaling pathway

Murine pre-osteoblasts and fibroblast cell lines were used to determine the effect of pulsed electromagnetic field (PEMF) exposure on the production of autocrine growth factors and the activation of early signal transduction pathways. Exposure of pre-osteoblast cells to PEMF minimally increased the amount of secreted TGF-beta after 1 day, but had no significant effects thereafter. PEMF exposure of pre-osteoblast cells also had no effect on the amount of prostaglandin E(2) in the conditioned medium. Exposure of both pre-osteoblasts and fibroblasts to PEMF rapidly activated the mTOR signaling pathway, as evidenced by increased phosphorylation of mTOR, p70 S6 kinase, and the ribosomal protein S6. Inhibition of PI3-kinase activity with the chemical inhibitor LY294002 blocked PEMF-dependent activation of mTOR in both the pre-osteoblast and fibroblast cell lines. These findings suggest that PEMF exposure might function in a manner analogous to soluble growth factors by activating a unique set of signaling pathways, inclusive of the PI-3 kinase/mTOR pathway.     

Maturation of arabidopsis seeds is dependent on glutathione biosynthesis within the embryo

Glutathione (GSH) has been implicated in maintaining the cell cycle within plant meristems and protecting proteins during seed dehydration. To assess the role of GSH during development of Arabidopsis (Arabidopsis thaliana [L.] Heynh.) embryos, we characterized T-DNA insertion mutants of GSH1, encoding the first enzyme of GSH biosynthesis, gamma-glutamyl-cysteine synthetase. These gsh1 mutants confer a recessive embryo-lethal phenotype, in contrast to the previously described GSH1 mutant, root meristemless 1(rml1), which is able to germinate, but is deficient in postembryonic root development. Homozygous mutant embryos show normal morphogenesis until the seed maturation stage. The only visible phenotype in comparison to wild type was progressive bleaching of the mutant embryos from the torpedo stage onward. Confocal imaging of GSH in isolated mutant and wild-type embryos after fluorescent labeling with monochlorobimane detected residual amounts of GSH in rml1 embryos. In contrast, gsh1 T-DNA insertion mutant embryos could not be labeled with monochlorobimane from the torpedo stage onward, indicating the absence of GSH. By using high-performance liquid chromatography, however, GSH was detected in extracts of mutant ovules and imaging of intact ovules revealed a high concentration of GSH in the funiculus, within the phloem unloading zone, and in the outer integument. The observation of high GSH in the funiculus is consistent with a high GSH1-promoterbeta-glucuronidase reporter activity in this tissue. Development of mutant embryos could be partially rescued by exogenous GSH in vitro. These data show that at least a small amount of GSH synthesized autonomously within the developing embryo is essential for embryo development and proper seed maturation.     

Comparison of two immunomagnetic separation technologies to deplete T cells from human blood samples

The objective of this study was to compare the performance of two immunomagnetic separation technologies to deplete T cells from buffy coats of human blood. Specifically, two versions of the commercial MACS(R) Technology: MiniMACS and SuperMACS, and a prototype, flow-through system, the QMS, were evaluated. Peripheral blood mononuclear leukocytes (PBL) were isolated from buffy coats and an immunomagnetic separation of CD3(+) cells was conducted using company and optimized labeling protocols. To mimic peripheral blood containing bone marrow purged hematopoietic stem cells, HSC, CD34 expressing-cells (KG1a) were spiked into PBL prior to T-cell depletion once optimized depletion conditions were determined. Once the labeling protocol was optimized, the MiniMACS system performed well by producing a highly enriched CD3(+) fraction, and a respectable level of depletion of T cells and recovery of KG1a cells in the depleted fraction; an average log(10) depletion of T cells of 2.88 +/- 0.17 and an average recovery of the KG1a cells of 60.8 +/- 5.94% (n = 14). The performance of the SuperMACS system was very similar with an average log(10) depletion of T cells of 2.89 +/- 0.22 and an average recovery of KG1a of 63.1 +/- 8.55% (n = 10). In contrast, the QMS system produced an average log(10) depletion of T cells of 3.98 +/- 0.33 (n = 16) with a corresponding average recovery of 57.9 +/- 16.6% of the spiked CD34+ cells. The aforementioned QMS performance values were obtained using sorting speeds ranging from 2.5 x 10(4) to 1.7 x 10(5) cells per second. It is suggested that the lack of a 100% recovery of the unlabeled KG1a cells is the result of a previously reported "drafting" phenomena which pulls unlabeled cells in the direction of the magnetically labeled cells thereby resulting in loss of the unlabeled cells.     

Anticancer efficacies of cisplatin-releasing pH-responsive nanoparticles

The objective of these investigations was to test the hypothesis that a rapid cytoplasmic release profile from nanoparticles would potentiate the anticancer activity of cisplatin. Cisplatin-loaded nanoparticles with pH-responsive poly[2-(N,N-diethylamino)ethyl methacrylate] (PDEA) cores were synthesized from PDEA-block-poly(ethylene glycol) (PDEA-PEG) copolymer by using a solvent-displacement (acetone-water) method. Nanoparticles with pH-nonresponsive poly(epsilon-caprolactone) (PCL) cores made from PCL-block-PEG (PCL-PEG) were used for comparison. Nanoparticle sizes, zeta potentials, drug-loading capacities, and pH responsiveness were characterized. The cellular uptakes and localization in lysosomes were visualized by using confocal fluorescence microscopy. Cytostatic effects of free and encapsulated cis-diammineplatinum(II) dichloride (cisplatin) toward human SKOV-3 epithelial ovarian cancer cells were estimated by using the MTT assay. Intraperitoneal tumor responses to cisplatin and cisplatin/PDEA-PEG were evaluated in athymic mice at 4-6 weeks postinoculation of SKOV-3 cells. PDEA-PEG nanoparticles dissolved at pH < 6 and rapidly internalized and transferred to lysosomes; it therefore was predicted that the PDEA nanoparticles would rapidly release cisplatin into cytoplasm upon integration into acidic lysosomes and thereby overwhelm the chemoresistant properties of SKOV-3 cells. Indeed, relative proportions of viable cells were diminished to a greater extent by exposure in vitro to fast-releasing nanoparticles compared to slow-releasing nanoparticles or an equivalent dose of free cisplatin. Incidences of cellular pyknosis (a morphological indicator of apoptosis) were most evident within intestinal/mesentery tumors of mice treated with cisplatin/PDEA-PEG; tumor burdens were correspondingly reduced.     

What might cause pain in the thyroid gland? Report of a patient with subacute thyroiditis of atypical presentation

Subacute granulomatous thyroiditis (SAT), also known as de Quervain's thyroiditis or painful subacute thyroiditis, is the commonest thyroid condition responsible for neck tenderness. Other causes of pain in the thyroid gland should be taken into consideration during differential diagnosis, especially when a patient presents with misleading or equivocal signs and symptoms. We report the case of a 39 year-old woman diagnosed as having SAT whose clinical, biochemical and radiological presentation varied significantly from the common SAT manifestation. A tentative diagnosis of SAT was made based on the presented symptoms, ultrasonography and fine-needle biopsy results. However, biochemical analysis suggested neither inflammatory process nor the presence of thyrotoxicosis. Moreover, technetium scan of the thyroid revealed normal uptake of the isotope and there was neither clinical nor ultasonographic response for corticosteroids. The patient's symptoms, despite being prescribed typical treatment, gradually deteriorated and the pain became increasingly debilitating. Eventually, the patient underwent total thyroidectomy. As a result, she has become free of symptoms, but the macroscopic picture of thyroid gland, noted during the operation, gave a suspicion of neoplastic process. Nevertheless, histological study of flow samples confirmed the tentative diagnosis of de Quervain's thyroiditis, despite all previous findings that were not suggestive of it. This report confirms the likelihood that SAT can present atypically. Additionally, it indicates that surgical treatment may be considered in patients with severe, debilitating, persistent thyroid gland pain connected with SAT clinical course.     

The Cu(II)-fluconazole complex revisited. Part I: Structural characteristics of the system

Protonation equilibria and Cu(II) binding processes by an antifungal agent fluconazole, α-(2,4-difluorophenyl)-α-(1H-1,2,4-triazol-1-yl-methyl)-1H-1,2,4-triazole-1-ethanol, were studied using the UV-Vis, EPR and NMR spectroscopic techniques. The protonation constant of fluconazole was determined from NMR titration and attributed to N4′ nitrogen atoms using the DFT methods. The spectroscopic data suggest that at pH as low as 0.4 the first complex is formed, in which one or two Cu(II) ions are bound to one of the nitrogen atoms (N4′) from triazole rings. Above pH 1.5 each Cu(II) ion is surrounded by two nitrogen atoms (also N4′) from two different ligand molecules, forming primary monomeric complexes and above pH = 5, both dimeric or oligomeric species occur, which is well registered by the EPR technique.The mixture of Cu(NO₃)₂ with fluconazole in a 1:1 molar ratio in a water (pH = 4.5)/ethanol solution gave crystals of [Cu₂(H₂O){(C₆H₃-2,4-F₂)(CH₂N₃C₂H₂)₂C-OH}{(C₆H₃-2,4-F₂)(CH₂N₃C₂H₂)₂C-O}(NO₃)](NO₃)₂·9(H₂O). This complex is the first example of a cupric 3D polymeric structure with a fluconazole ligand coordinated via both N2′ and N4′ atoms from the same triazole rings. At higher pH values, we obtained a binuclear complex [Cu₂(L)₂(H₂O)₂(NO₃)₂], in which the copper(II) atoms were bridged by the oxygen atoms of the deprotonated OH group of fluconazole.The hypothetical oxidative properties of this system were also examined, however it failed to generate either reactive oxygen species or DNA scission products.     

Dysfunctional HDL: A novel important diagnostic and therapeutic target in cardiovascular disease?

High density lipoprotein (HDL) has many properties, which contribute to its atheroprotective role. However, some recent clinical trials have identified subjects with the progression of atherosclerosis despite normal levels of HDL cholesterol. This raises the question if all subfractions of HDL have the same properties. Moreover, recent investigations have shown that both acute and chronic inflammation may lead to structural and functional changes of HDL, which render the particles proinflammatory. Although therapeutic agents that increase HDL levels are now quite well established it is not clear whether they influence HDL quality. We review the current state of knowledge on the properties of HDL and factors/therapeutic agents which may restrain the transformation of normal HDL into dysfunctional HDL.