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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aromatic l-amino acid decarboxylase (AADC) is necessary for conversion of l-DOPA to dopamine. Therefore, AADC gene therapy has been proposed to enhance pharmacological or gene therapies delivering l-DOPA. However, addition of AADC to the grafts of genetically modified cells expressing tyrosine hydroxylase (TH) and GTP cyclohydrolase 1 (GCH1), which produce l-DOPA in parkinsonian rats, resulted in decreased production of l-DOPA and dopamine owing to feedback inhibition of TH by dopamine. End-product feedback inhibition has been shown to be mediated by the regulatory domain of TH, and site-specific mutation of serine 40 makes TH less susceptible to dopamine inhibition. Therefore, we investigated the efficacy of using TH with serine 40 mutated to leucine (mTH) in an ex vivo gene-therapy paradigm. Primary fibroblasts (PF) from Fischer 344 rats were transduced with retrovirus to express mTH or wild-type rat TH cDNA (wtTH). Both cell types were also transduced with GCH1 to provide the obligate TH cofactor, tetrahydrobiopterin. PF transfected with AADC were used as coculture and cografting partners. TH activities and l-DOPA production in culture were comparable between PFwtTHGC and PFmTHGC cells. In cocultures with PFAADC cells, PFmTHGC cells showed significant reduction in the inhibitory effect of dopamine compared with PFwtTHGC cells. In vivo microdialysis measurement showed that cografting PFAADC cells with PFmTHGC cells resulted in smaller decreases in l-DOPA and no reduction in dopamine levels compared with cografts of PFAADC cells with PFwtTHGC cells, which decreased both l-DOPA and dopamine levels. Maintenance of dopamine levels with lower levels of l-DOPA would result in more focused local delivery of dopamine and less potential side-effects arising from l-DOPA diffusion into other structures. These data support the hypothesis that mutation of serine 40 attenuates TH end-product inhibition in vivo and illustrates the importance of careful consideration of biochemical pathways and interactions between multiple genes in gene therapy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Magnetoresistance measurements can be used during manufacturing to characterize basic magnetic parameters at the device level. A fruitful approach is to take advantage of the gradient field generated by the current flowing through the sample. This method was employed by Smith et al. in an elegant series of experiments that led to precise measurements of exchange constant in soft magnetic thin films. In the present paper, local coupling in bilayers, anisotropy, and interface quality are investigated using magnetoresistive response to gradient fields. Permalloy samples consisting of two sputtered layers (0.1 μm thick) separated by thin SiO2 spacers were patterned in the form of long stripes parallel to the easy axis. Variation in resistance was measured as a function of external field applied in the easy-axis direction and of current density. For similar geometries, the samples have similar resistance. The curves display a sharp decrease in the resistance near zero field that is associated with the reversal of the magnetization in the stripe. Once the sample has switched, coupled layers have a flat response versus field: exchange coupling between the layers constrains the fanning of the magnetization, as previously described. For uncoupled or weakly coupled samples, the curves show curvature at higher fields, and the curvature increases markedly with current density. The fanning within each layer is constrained by exchange, but the average magnetization in one layer rotates under the influence of the field generated by the current in the other layer.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 177-179 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The addition of 0.4–8.6 at. % Co to Cu thin films strongly influences the temperature evolution of microstructure, stress, and resistivity. For concentrations near 1 at. % Co in coevaporated Cu-Co on oxidized Si, normal grain growth begins at about 75 °C, about 50 °C lower than in pure Cu. There is an abrupt decrease in resistivity and stress at a temperature which increases with Co content from 120 °C (0% Co) to 250 °C (8.6 at. % Co), and coincides with precipitation of Co within Cu grains. A dramatic change in texture is observed in both coevaporated and electroplated Cu-Co films upon annealing above 250 °C. As-deposited films have a three-component texture of (111) fiber, (200) fiber, and random but annealed films have a dominant (200) fiber texture. This "cube'' texture differs from the dominant (111) texture of annealed pure Cu, and appears to be coupled to an abnormal grain growth process since many grains are observed to be larger than ten times the film thickness. It is proposed that segregation of Co to external surfaces or to Cu grain boundaries may favor this (200) texture by selectively affecting grain-boundary mobility or the surface energy driven grain growth.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 76 (2000), S. 360-362 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It has been found that atomic force microscope (AFM) induced local oxidation is an effective way for converting thin (〈5 nm) Si3N4 films to SiOx. The threshold voltage for the 4.2 nm film is as low as 5 V and the initial growth rate is on the order of 103 nm/s at 10 V. Micro-Auger analysis of the selectively oxidized region revealed the formation of SiOx. Due to the large chemical selectivity in various etchants and great thermal oxidation rate difference between Si3N4, SiO2, and Si, AFM patterning of Si3N4 films can be a promising method for fabricating nanoscale structures. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Molecular Structure 157 (1987), S. 155-165 
    ISSN: 0022-2860
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0942-0940
    Keywords: Keywords: Hemifacial spasm; microvascular decompression; magnetic resonance angiography; facial nerve.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary  Background. The objective of this study was to investigate the role of preoperative three dimensional short-range magnetic resonance angiography (3D-TOF MRA) in predicting the clinical outcomes following microvascular decompression for the treatment of hemifacial spasm.  Method. Preoperative magnetic resonance (MR) imaging was performed on all patients with hemifacial spasm (564 cases) between January 1992 and September 1998. Of the 564 patients, 440 patients were included in this retrospective study. The presence of vascular contact, offenders, and anomalies in the vertebro-basilar system, were determined by 3D-TOF MRA prior to microvascular decompression of the facial nerve. The preoperative findings were compared with the surgical findings and clinical outcomes.  Findings. A correlation was found between the clinical outcome (p〈0.01) and the presence of a vascular indentation at the root entry zone (REZ) of the facial nerve. A shift of the vertebrobasilar system to the symptomatic side was found in 214 (48.6%) patients with hemifacial spasm, compared to only 10 (13.5%) patients in the control group (p〈0.01). The unilateral vertebral artery was observed in 43 (9.8%) patients with hemifacial spasm and in 8 (10.8%) of the control patients. A hypoplasia of the artery was found in 8 (1.8%) patients with hemifacial spasm and in 1 (1.4%) control patient. The compressing offenders in the patients, discovered by MRI in conjunction with MRA, were as follows: 45.9% (202 patients) in the anterior inferior cerebellar artery (AICA), 34.8% (153 patients) in the posterior inferior cerebellar artery (PICA), 12.5% (55 patients) in the vertebral artery (VA) and 6.8% (30 patients) in multiple vessels. In contrast to the compressing offenders seen on the MRA, the offenders confirmed during surgery were as follows: 43% (189 patients) in the AICA, 36.4% (160 patients) in the PICA, 1.4% (6 patients) in the VA, 19% (84 patients) in multiple vessels, and 0.2% (1 patient) in the vein.  In our long-term follow-up series of the 440 patients with hemifacial spasm, an excellent surgical outcome was obtained in 86.3% of cases and a good outcome was achieved in 6.4% (mean follow-up duration, 45.5 months).  Interpretation. Preoperative 3D-TOF MRA can identify the relationship between the facial nerve and adjacent vessels in patients with a hemifacial spasm and assist in preoperative planning. This study suggests that 3D-TOF MRA is useful for selecting appropriate patients for surgical treatment and, to some extent, as an additional role for predicting the clinical outcome.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1607-1612 
    ISSN: 0887-6266
    Keywords: neutron scattering (SANS) from hot stretched polystyrene ; polystyrene, hot stretched, SANS study of ; chain deformation in hot stretched polystyrene, SANS study of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small-angle neutron scattering (SANS) has been used to investigate macromolecular orientation of uniaxially hot-stretched partially deuterated polystyrene. Principle radii of gyration and degree of eccentricity were measured over a range of hot-stretch temperatures, strain rates, and external draw ratios (EDR). Results show affine deformation for EDR 〈4 and an increase in the degree of local molecular orientation with increasing rate of strain and decreasing stretching temperature. It also is found that although the macromolecules follow the external stretching affinely on average, they do not deform uniformly.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Formation of Organosilicon Compounds. LVII. Investigations on the Reaction of (Cl3Si—CCl2)2SiCl2 with LiCH3(Cl3Si—CCl2)2SiCl2 1 reacts with excessive Lime (me = CH3) to form compounds 2, 3, 4, 5, 1.1.2.3.3.4,4-Heptamethyl-2-trimethylsilyl-1, 3-disila-cyclobutane 6 and 7; by cleavage of 1 the compounds 8 and 9 are formed. Compound 3 results from a 1.3-isomerisation of 4. Study of the nmr-spectra shows that the reaction of 1 with Lime resp. meMgCl starts with metallation of the bridging C-atom. In the reaction with Lime the methylation of the C-Atoms occur more rapidly by than the methylation of the Si-atoms, whereas the Si-methylation is predominant in the reaction with meMgCl. Mechanism of the reaction is discussed.
    Notes: (Cl3Si—CCl2)2SiCl2 1 reagiert mit einem Überschuß Lime (me = CH3) unter Bildung von Sime4 2, H2C=C(Sime3)[CH(Sime3)2] 3, (me3Si)2C=C(Sime3)CH3 4, (me3Si)2C=C(Sime3)H 5 und 1,1,2,3,3,4,4-Heptamethyl-2-trimethylsilyl-1, 3-disila-cyclobutan 6 neben und den durch Spaltung von 1 entstehenden Verbindungen me3Si—CHme—Sime3 8 und me3Si—Cme2—Sime3 9. Verbindung 3 entsteht über eine 1,3-Isomerisierung aus 4. Nach der NMR-Untersuchung beginnt die Umsetzungen von 1 sowohl mit Lime als auch mit meMgCl mit der Ummetallierung am Brücken-C-Atom. Bei der Reaktion mit Lime setzt die C-Methylierung früher ein als die Si-Methylierung. Bei der Umsetzung mit meMgCl ist die Si-Methylierung vorrangig. Es wird der Reaktionsmechanismus angegeben.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Publication Date: 2011-08-10
    Description: Author(s): D. K. Singh, A. Thamizhavel, S. Chang, J. W. Lynn, D. A. Joshi, S. K. Dhar, and S. Chi We report on experimental evidence for a coupling between the magnetic-field-induced fluctuations of correlated Ce ions coinciding with the discontinuous movement of the underlying spin-density wave in the intermetallic rare-earth compound CeAg 2 Ge 2 . The measurements performed using neutron scatterin... [Phys. Rev. B 84, 052401] Published Tue Aug 09, 2011
    Keywords: Magnetism
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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  • 10
    Publication Date: 2017-10-07
    Description: One of the most common persistent organic pollutants is di-(2-ethylhexyl) phthalate (DEHP), which has caused considerable pollution in the Mollisols of agricultural areas in northeast China. This research investigates the effects of different concentrations of DEHP from 0 to 35 days on microbial biomass carbon (MBC) and structural diversity in the microbial community of Mollisols. The results indicated that contamination by DEHP of more than 20 mg kg −1 could clearly affect MBC and structural diversity of the microbial community of a Mollisol in a short time depending on the dose of DEHP. At concentrations of DEHP 〉20 mg kg −1 , we observed that the larger was the concentration of DEHP, the greater was the effect on the MBC and diversity of the soil microbial community. The DEHP concentration or incubation time had negative correlations with MBC, and the evenness ( E H ), Shannon ( H ) and richness ( S ) indices of the microbial community, and the DEHP concentration had a dominant effect on microbial properties. The dominant bacterium in the DEHP-contaminated soil was B acillus . Furthermore, bacterial community structure changed under different amounts of DEHP stress and with the increase in incubation time; Pseudomonas and Sphingopyxis clearly increased in number with large concentrations of DEHP. The change in the microbial population indicated that these two bacteria might have a strong resistance to change under the microbial DEHP stress. Highlights DEHP significantly changed MBC and microbial diversity of a Mollisol. The change in MBC was related to the composition of the soil microbial community structure. DEHP had a persistent effect on the microbial community in a Mollisol. Bacillus were the dominant bacteria in the DEHP-contaminated soil.
    Print ISSN: 1351-0754
    Electronic ISSN: 1365-2389
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Wiley-Blackwell
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