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  • 1
    ISSN: 0920-9964
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: diuretics ; antihypertensive agents ; renal disease ; dispositon ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacodynamic actions and disposition of diuretic and antihypertensive agents may be significantly modified in subjects with renal disease. Most studies on this question have dealt with alterations in the elimination kinetics of these drugs and, while they generate descriptive data, minimal insight about changes in dose-response relationships or mechanisms of drug action are provided by such investigations. Several basic principles which may serve as useful guidelines in determining how renal failure will influence the response to drugs have been considered. They include the following: degree of renal malfunction, intrinsic toxicity of the drug, alternative pathways for drug metabolism and elimination, elimination pharmacokinetics and dose-response characteristics. Several classes of diuretic agents (thiazides, furosemide) and antihypertensive drugs (hydralazine, methyldopa, propranolol, prazosin, and clonidine) have been used as models to define how basic knowledge of renal and non-renal pathways for elimination of drugs and their pharmacodynamic actions may assist in establishing rational therapeutic regimens for these agents in patients with renal failure.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: β-endorphin is an endogenous opioid peptide that has been hypothesized to be involved in the behavioral effects of drugs of abuse including psychostimulants. Using microdialysis, we studied the effect of cocaine on extracellular levels of β-endorphin in the nucleus accumbens, a brain region involved in the reinforcing effects of psychostimulant drugs. Experimenter-delivered cocaine (2 mg/kg, i.v.) increased extracellular β-endorphin immunoreactive levels in the nucleus accumbens, an effect attenuated by 6-hydroxy-dopamine lesions or systemic administration of the D1-like receptor antagonist, SCH-23390 (0.25 mg/kg, i.p.). The effect of cocaine on β-endorphin release in the nucleus accumbens was mimicked by a local perfusion of dopamine (5 µm) and was blocked by coadministration of SCH-23390 (10 µm). Self-administered cocaine (1 mg/kg/infusion, i.v.) also increased extracellular β-endorphin levels in the nucleus accumbens. In addition, using functional magnetic resonance imaging, we found that cocaine (1 mg/kg, i.v.) increases regional brain activity in the nucleus accumbens and arcuate nucleus. We demonstrate an increase in β-endorphin release in the nucleus accumbens following experimenter-delivered and self-administered cocaine mediated by the local dopaminergic system. These findings suggest that activation of the β-endorphin neurons within the arcuate nucleus–nucleus accumbens pathway may be important in the neurobiological mechanisms underlying the behavioral effects of cocaine.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A 68-year-old woman presented with a 10-year history of multiple milia on her scalp. Spontaneous eruptive milia are uncommon and the term describes cases that are more extensive in number and distribution than would be expected in primary milia.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European spine journal 2 (1993), S. 209-214 
    ISSN: 1432-0932
    Keywords: Disque intervertébral ; Fatigue ; Rupture ; Mécanique ; Flexion ; Intervertebral disc ; Fatigue ; Failure ; Mechanics ; Bending
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Part I of this study showed that collagen fibres do need not need to be continuous to reinforce the annulus fibrosus, and that 15-mm-wide samples of annulus retain about 44% of their in situ stiffness and strength when stretched vertically. Part II investigated the ultimate tensile strength (UTS) and fatigue life of such samples. Vertical slices, 5 mm thick and 30 mm wide, were cut from the anterior and posterior margins of the annulus and adjacent vertebral bodies. Each slice was divided sagittally to obtain a matched pair of specimens. The bony ends of each specimen were secured in a materials testing machine so that the annulus could be stretched vertically, as occurs during bending movements of the spine in life. One of each pair of specimens was stretched to failure to obtain its UTS; the other was cyclically loaded at some fraction of the UTS until failure occurred. Tensile failure started with the hyaline cartilage end-plate being stripped off the underlying bone and ended with the most peripheral annular fibres pulling out of the matrix. The estimated in situ strength in the vertical direction was 3.9 MPa for the anterior annulus and 8.6 MPa for the posterior annulus. Fatigue failure could occur in less than 10000 cycles if the tensile force exceeded 45% of the UTS. The results explain why radial fissures often fail to penetrate the peripheral annulus. When compared with in vivo measurements of spinal loading, they suggest that repetitive forward bending movements could cause fatigue failure of the posterior annulus.
    Notes: Résumé La première partie de cette étude a montré que les fibres de collagène ne doivent être en continuité pour renforcer l'anneau fibreux et que des échantillons d'annulus de 15 mm de largeur conservent environ 44% de leur rigidité in-situ et de leur résistance lorsqu'ils sont soumis à un étirement vertical. La seconde partie a exploré la limite de résistance à la tension (Ultimate Tensile Strength= UTS) et le comportement à la fatigue de tels échantillons. Des tranches verticales e disque de 5 mm d'épaisseur et de 30 mm de largeur ont été taillées à partir des bords latéraux de l'annulus et des corps vertébraux adjacents. Chaque tranche a été divisée sagittalement pour obtenir une paire d'échantillons identiques. Les extrémités osseuses de chaque tranche ont été fixées dans un appareil destiné à tester les matériaux de manière à ce que l'annulus puisse être étiré verticalement, comme cela se produit lors des mouvements de flexion du rachis dans la vie courante. L'un des deux échantillons de chaque paire a été étiré jusqu'à sa rupture pour déterminer sa limite de résistance à la tension (UTS); l'autre a été soumis à une charge cyclique égale à une fraction de l'UTS jusqu'à obtenir sa rupture. La rupture sous tension a commencé par l'arrachement du cartilage hyalin du plateau de l'os sous-jacent et s'est terminé par l'arrachement des fibres les plus périphériques de l'anneau hors de leur matrice. La résistance in-situ estimée dans le sens vertical était de 3,9 MPa pour la partie antérieure de l'annulus et de 8,6 MPa pour la partie postérieure de l'annulus. La rupture de fatigue pourrait survenir en moins de 10000 cycles si la force de tension venait à dépasser 45% de l'UTS. Ces résultats expliquent pourquoi les fissures radiaires manquent souvent de pénétrer la partie périphérique de l'anneau fibreux. Lorsqu'on les compare aux mesures, in vivo de la mise en charge rachidienne, nos résultats suggèrent que les mouvements répétés de flexion antérieure du rachis pourraient provoquer une rupture de fatigue de la partie postérieure de l'anneau fibreux.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European spine journal 2 (1993), S. 203-208 
    ISSN: 1432-0932
    Keywords: Disque intervertébral ; Collagène ; Protéoglycans ; Mécanique ; Renforcement fibrillaire ; Intervertebral disc ; Collagen ; Proteoglycans ; Mechanics ; Fibre reinforcement
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary We investigated the tensile properties of samples of human lumbar annulus fibrosus. Here we consider the effect of sample size, and hence collagen disruption, on the results obtained. Vertical slices, 5 mm thick and 30 mm wide, were cut from the lateral margins of the annulus and adjacent vertebral bodies. The bony ends of each slice were secured in a materials testing machine so that the annulus could be stretched vertically, as occurs during bending movements of the spine in life. Tensile stiffness was measured repeatedly after successive vertical cuts in the annulus had reduced the effective size of the sample. Stiffness (per unit cross-sectional area) decreased as the specimen size decreased. The mean length of collagen fibre bundles in the specimens was calculated from a geometrical model and shown to be proportional to the tensile stiffness. Extrapolation of the results suggested that the vertical stiffness and strength of 15-mm-wide specimens of annulus would be about 44% of their values in situ. We conclude that collagen fibres need not be continous to reinforce the annulus and that fibre-matrix interactions make a large contribution to the tensile stiffness and strength.
    Notes: Résumé Nous avons étudié les propriétés mécaniques d'échantillons d'anneau fibreux de disques lombaires humains soumis à la tension. La première partie de ce travail étudie l'effet de la taille de l'échantillon et de la rupture du collagène sur le résultat obtenu. Des tranches verticales de disque de 5 mm d'épaisseur et de 30 mm de largeur ont été taillées à partir des bords latéraux de l'annulus et des corps vertébraux adjacents. Les extrémités osseuses de chaque tranche ont été fixées dans un appareil destiné à tester les matériaux de manière à ce que l'annulus puisse être étiré verticalement, comme cela se produit lors des mouvements de flexion du rachis dans la vie courante. La raideur sous tension a été mesurée de manière répétitive après réduction de la taille effective de l'échantillon par des sections verticales successives de l'annulus. La raideur (par unité de surface) a diminué avec la taille du spécimen. La longueur moyenne des faisceaux de fibres de collagène dans les échantillons étudiés a été calculée à partir d'un modèle géométrique et il apparaît qu'elle est proportionnelle à la raideur sous tension. L'extrapolation des résultats a suggéré que la rigidité verticale et la solidité d'échantillons d'annulus de 15 mm de largeur devrait se situer autour de 44% de leur valeur in-situ. En conclusion, les fibres de collagène doivent être en continuité pour renforcer l'annulus, et les interactions fibresmatrice contribuent largement à la rigidité sous tension et à la résistance.
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    ISSN: 0020-7373
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Computer Science
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of cutaneous pathology 14 (1987), S. 0 
    ISSN: 1600-0560
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Twenty instances of verruca vulgaris, equally divided between oral mucosa and lip vermillion, were assayed for the presence of human papillomavirus (HPV) capsid antigen and type-specific DNA employing in situ hybridization methods. All 10 cases arising on lip vermilion expressed capsid antigen and harbored HPV Type 2 genomes as assessed under conditions of high stringency DNA hybridization. Oral verrucae rarely expressed capsid antigen; HPV Type 2 genomes were encountered in 20% of the cases.
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 523-528 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Particle beams have been developed at the Culham Laboratory for many years, mainly for application to the production of high-temperature plasmas. These developments included demonstration of fundamental plasma physics such as particle trapping, heating, and current drive coupled to continuous advances in the physics and technology of ion beam production and transport. This work reached its zenith in production of multimegawatt high-proton fraction sources for the neutral beam injectors for JET. A new initiative is now coming for the development of negative ion based injectors. This wide ranging base of physics and technology provided a springboard for exploitation of beams in areas other than fusion. The last few years have seen increasing R and D at Culham in areas such as space, defense, surface treatment, and implantation. The applications have ranged from beams of H+ or H− to Xe+, from currents of less than 1 mA to currents of amperes and from energies of 50 eV to energies of hundreds of kilovolts. This paper describes some examples of these activities and relates them to the physics and technology base. Future areas of interest are also discussed.
    Type of Medium: Electronic Resource
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