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  • 1
    ISSN: 1573-6903
    Keywords: Blood-brain barrier ; hypothalamic extract ; astrocyte ; capillary endothelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to investigate the influence of hypothalamic extract, astrocyte co-culture, and astrocyte-conditioned medium on the barrier function of an in vitro model of the blood-brain barrier. Porcine brain capillary endothelial cells were grown on polycarbonate membranes suspended between two chambers of media, representing the capillary lumen and brain interstitium. Endothelial cells grown alone and cocultured with astrocytes were cultured in growth medium with or without 50 μg/mL hypothalamic extract. An additional treatment consisted of endothelial cells cultured in growth medium that was first conditioned by astrocytes. Coculture consisted of a noncontact model with astrocytes attached to the bottom of the abluminal chamber. Barrier function of the endothelial cells was tested on days 1 through 9 post-seeding by measuring permeability to macromolecules (albumin) and small ions (electrical resistance). Resistance to the passage of macromolecules and small ions was greatest for endothelial cells grown without astro-cytes in growth medium supplemented with hypothalamic extract. This barrier was maximal during days 4 through 7 post-seeding and was significantly less permeable than the barrier formed by endothelial cells grown in un-supplemented growth medium, in coculture with astrocytes, or in astrocyte-conditioned medium. These results demonstrate that a noncontact coculture with astro-cytes did not enhance the integrity of this in vitro BBB model employing porcine brain capillary endothelial cells, but barrier function was increased when the model's medium was supplemented with hypothalamic extract.
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  • 2
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 3
    ISSN: 0749-503X
    Keywords: Saccharomyces cerevisiae ; metal ion toxicity ; vacuole ; protein sorting ; gene regulation ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The metal ions, Cu2+/+ and Fe3+/2+, are essential co-factors for a wide variety of enzymatic reactions. However, both metal ions are toxic when hyper-accumulated or maldistributed within cells due to their ability to generate damaging free radicals or through the displacement of other physiological metal ions from metalloproteins. Although copper transport into yeast cells is apparently independent of iron, the known dependence on Cu2+ for high affinity transport of Fe2+ into yeast cells has established a physiological link between these two trace metal ions. In this study we demonstrate that proteins encoded by genes previously demonstrated to play critical roles in vacuole assembly or acidification, PEP3, PEP5 and VMA3, are also required for normal copper and iron metal ion homeostasis. Yeast cells lacking a functional PEP3 or PEP5 gene are hypersensitive to copper and render the normally iron-repressible FET3 gene, encoding a multi-copper Fe(II) oxidase involved in Fe2+ transport, also repressible by exogenous copper ions. The inability of these same vacuolar mutant strains to repress FET3 mRNA levels in the presence of an iron-unresponsive allele of the AFT1 regulatory gene are consistent with alterations in the intracellular distribution or redox states of Fe3+/2+ in the presence of elevated extracellular concentrations of copper ions. Therefore, the yeast vacuole is an important organelle for maintaining the homeostatic convergence of the essential yet toxic copper and iron ions. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 6 Ill.
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  • 4
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] The mechanism by which mutations in the presenilin (PS) genes cause the most aggressive form of early-onset Alzheimer's disease (AD) is unknown, but fibroblasts from mutation carriers secrete increased levels of the amyloidogenic Aβ42 peptide, the main component of AD plaques. We established ...
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  • 5
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The jet-cooled B˜ 1B2–X˜ 1A1 spectrum of silylidene, the simplest unsaturated silylene, has been observed for the first time. H2C=Si and D2C=Si have been produced by an electric discharge through tetramethylsilane and tetramethylsilane-d12 vapor diluted in argon at the exit of a supersonic expansion. Rotational analysis of the 000 bands yielded the following substitution structures: rs″(CSi)=1.706(5) Å, rs″(CH)=1.099(3) Å, θs″(HCH)=114.4(2)°, rs′(CSi)=1.815(5) Å, rs′(CH)=1.073(4) Å, and θs′(HCH)=133.7(1)°. The electronic transition consists primarily of strong electronically allowed perpendicular bands, but a weaker system of vibronically induced parallel bands has also been assigned. Transitions involving Δv=2 changes in the ν6 (b2) mode show up prominently in the spectrum, due to a very large change in the vibrational frequency on excitation. Silylidene has very interesting excited state decay dynamics. Anomalous S2−S0 fluorescence is observed due to the very large S2−S1 energy gap. Rotational level specific intensity anomalies are found in the laser induced fluorescence spectra. Collision-free fluorescence decay curves exhibit superimposed quantum beats for almost all the accessible rotational levels in the 000 bands of H2CSi and D2CSi. Density of states arguments lead to the conclusion that most of the beat patterns are due to coupling with high vibrational levels of the ground state, although two examples of hyperfine splittings associated with singlet–triplet interactions have also been found. © 1997 American Institute of Physics.
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  • 6
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The ground and first excited singlet states of monochlorosilylene have been reexamined using pulsed discharge jet and laser induced fluorescence techniques. HSiCl and DSiCl have been produced by an electric discharge through SiHCl3 and SiDCl3 vapor in argon. The 000 band rotational constants of four isotopomers of HSiCl and the harmonic force fields for both states have been combined to obtain the following estimates of the equilibrium structures: r′′(SiCl)=2.067(3) Å, r′′(SiH)=1.525(5) Å, θ′′(HSiCl)=96.9(5)°, r(SiCl)=2.040(3) Å, r(SiH)=1.532(8) Å, and θ(HSiCl)=118.1(5)°. Previous anomalies in the ground-state structure and the excited-state vibrational frequencies have been resolved. The radiative lifetime of the 480–400 nm (A˜ 1A′′–X˜ 1A) band system of HSiCl has been measured to be 432±20 ns. © 1997 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 106 (1997), S. 7479-7490 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The vibrational and electronic spectra of hexafluorothioacetone, (CF3)2CS, a novel blue gas, have been studied. Ab initio calculations of the vibrational properties of CF3COF, CF3CSF, and (CF3)2CO were used to establish the feasibility and effectiveness of using theoretical predictions in the analysis of the spectra of perfluorinated compounds. These predictions have allowed us to obtain revised interpretations of the spectra of trifluoroacetyl fluoride and trifluorothioacetyl fluoride that are consistent with both experiment and theory and have allowed us to confirm a previous theoretical and experimental study of the spectrum of hexafluoroacetone. Similar calculations on hexafluorothioacetone predicted a ground state of C2 symmetry, with the CF3 groups staggered in an antieclipsed configuration and a pattern of vibrational frequencies similar to that of hexafluoroacetone. The gas phase and argon matrix infrared spectra and the Raman spectrum of hexafluorothioacetone were analyzed with the aid of the ab initio predictions and 20 of the 24 fundamentals were assigned. The blue color of the compound originates from very weak T1–S0 (800–675 nm) and S1–S0 (725–400 nm) transitions in the visible due to the n–π* electron promotion. Promotion of an electron from the π to the π* orbital gives rise to a very strong electronic transition in the 230–190 nm region of the ultraviolet. No emission was observed on laser excitation of hexafluorothioacetone in the visible. © 1997 American Institute of Physics.
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  • 8
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
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  • 9
    ISSN: 1432-198X
    Keywords: Key words: Hypophosphatemic rickets ; X-linked hypophosphatemia ; Growth hormone ; Bone mineral density
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The impact of recombinant human growth hormone (rhGH) treatment on growth, bone mineral metabolism, and bone mineral density (BMD) was evaluated in six children (3 girls, 3 boys) with familial hypophosphatemic rickets (XLH). Five were prepubertal (aged 6–8.8 years), one 15.3-year-old boy had combined XLH and GH deficiency, but had not been treated with rhGH previously. rhGH was administered daily for 1 year, at a dose of 1 IU/kg per week, combined with 1,25-dihydroxyvitamin D3 and oral phosphate therapy. Z scores for growth velocity and height improved significantly (–2.9 vs. 2.5, P 〈0.01, and –2.2 vs. –1.5, P 〈0.01, respectively). However, the ratio of Z score for height to that of subischial leg length decreased significantly (0.65 vs. 0.43, P 〈0.01), indicating disproportionate growth in favor of the trunk. The height-corrected BMD Z increased slightly (–0.99 vs. –0.94, P 〈0.05). A slight increase in serum phosphate occurred (0.78 vs. 0.88 mmol/l, P 〈0.02). Tubular reabsorption of phosphate/glomerular filtration rate increased from 0.45 mmol/l to 0.55 mmol at 6 months (P 〈0.02), but returned to the initial level at 12 months. These results indicate that children with XLH can benefit from the positive effect of rhGH on growth, however treatment could aggravate the already existing tendency to disproportionate growth. GH production should be evaluated in poorly growing patients with XLH, because it can mask GH deficiency. rhGH can be safely combined with conventional treatment in XLH. Further studies are needed to determine the effect of treatment on final height and maximal BMD.
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  • 10
    ISSN: 1423-0127
    Keywords: Cell-mediated immunity ; Lymphocyte proliferation ; HIV-1 ; β-Chemokines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The impairment of lymphocytes to proliferate to HIV antigen is a relatively early functional defect of cell-mediated immunity found in HIV-infected individuals. The finding of strong proliferative responses in nonprogressive HIV disease as well as its inverse association with viral load and clinical manifestation of AIDS supports the further use of this marker as a surrogate of disease progression. The observation that HIV-specific lymphocyte proliferation is associated with the production of CD8-derived HIV suppressive factors such as the β-chemokines further supports this conclusion. These functional immune measurements provide an additional marker to monitor disease progression in HIV-infected individuals, along with the current standards of CD4 counts and viral load.
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