| 1. |
- Abbas, Abdul-Karim, 1959, et al.
(författare)
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Bicarbonate-sensitive cysteine induced elevation of extracellular aspartate and glutamate in rat hippocampus in vitro
- 1997
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Ingår i: Neurochemistry International. - 0197-0186. ; 30:3, s. 253-259
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Tidskriftsartikel (refereegranskat)abstract
- The effect of different concentrations of cysteine (0.125, 0.25, 0.5 and 1 mM) on the net efflux of endogenous amino acids was studied by the incubation of rat hippocampal slices. Addition of cysteine (1 mM) in bicarbonate containing low K+ medium (5 min) selectively increased the basal net efflux of glutamate and aspartate by 370% and 396%, respectively. High K+ media (50 mM) containing cysteine (1 mM) evoked the net efflux of glutamate and aspartate by 1 454% and 1 019%, respectively. The corresponding effects in control slices without cysteine were 669% and 404%, respectively. No changes were observed on the concentrations of GABA, glutamine and taurine. The cysteine oxidation products, cysteine sulfinate (0.5 μM) and cystine (0.25 mM) were without effects. The effect of cysteine (0.5 mM) was dramatically reduced in media with no added bicarbonate/CO2. Thus, cysteine in a bicarbonate-sensitive manner selectively increases the extracellular concentration of excitotoxic amino acids in adult rat brain in vitro, possibly by interfering with the carrier-mediated glutamate uptake/ release
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| 2. |
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| 3. |
- Abel, Frida, 1974, et al.
(författare)
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Gain of chromosome arm 17q is associated with unfavourable prognosis in neuroblastoma, but does not involve mutations in the somatostatin receptor 2(SSTR2) gene at 17q24.
- 1999
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Ingår i: British journal of cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 81:8, s. 1402-9
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Tidskriftsartikel (refereegranskat)abstract
- Deletion of chromosome arm 1p and amplification of the MYCN oncogene are well-recognized genetic alterations in neuroblastoma cells. Recently, another alteration has been reported; gain of the distal part of chromosome arm 17q. In this study 48 neuroblastoma tumours were successfully analysed for 17q status in relation to known genetic alterations. Chromosome 17 status was detected by fluorescence in situ hybridization (FISH). Thirty-one of the 48 neuroblastomas (65%) showed 17q gain, and this was significantly associated with poor prognosis. As previously reported, 17q gain was significantly associated with metastatic stage 4 neuroblastoma and more frequently detected than both deletion of chromosome arm 1p and MYCN amplification in tumours of all stages. 17q gain also showed a strong correlation to survival probability (P = 0.0009). However, the most significant correlation between 17q gain and survival probability was observed in children with low-stage tumours (stage 1, 2, 3 and 4S), with a survival probability of 100% at 5 years from diagnosis for children with tumours showing no 17q gain compared to 52.5% for those showing 17q gain (P = 0.0021). This suggests that 17q gain as a prognostic factor plays a more crucial role in low-stage tumours. Expression of the somatostatin receptor 2 (SSTR2), localized in chromosome region 17q24, has in previous studies been shown to be positively related to survival in neuroblastoma. A point mutation in the SSTR2 gene has earlier been reported in a human small-cell lung cancer. In this study, mutation screening of the SSTR2 gene in 43 neuroblastoma tumours was carried out with polymerase chain reaction-based single-stranded conformation polymorphism/heteroduplex (SSCP/HD) and DNA sequencing, and none of the tumours showed any aberrations in the SSTR2 gene. These data suggest that mutations in the SSTR2 gene are uncommon in neuroblastoma tumours and do not correlate with either the 17q gain often seen or the reason some tumours do not express SSTR2 receptors. Overall, this study indicates that gain of chromosome arm 17q is the most frequently occurring genetic alteration, and that it is associated with established prognostic factors.
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| 4. |
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| 5. |
- Abrahamsson, Hans, 1966, et al.
(författare)
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A Turbulent Plane 2-Dimensional Wall-Jet in a Quiescent Surrounding
- 1994
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Ingår i: European Journal of Mechanics/B-Fluids. - 0997-7546 .- 1873-7390. ; 13:5, s. 533-556
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Tidskriftsartikel (refereegranskat)abstract
- An experimental investigation of the turbulence field in a plane two-dimensional wall-jet has been conducted. All measurements were carried out employing hot-wire techniques in a large scale experimental facility. Mean velocities, Reynolds stresses and wall shear stress were determined with slot Reynolds numbers of 1.0*104, 1.5*104 and 2.0*104. The wall-jet was found to be self-preserving, and an asymptotic scale matching was used to show the existence of a short inertial sub layer as compared with a wall boundary layer. Studies of the integral scale development and the turbulent diffusion of shear stress showed a strong interaction between the inner and outer regions of the wall-jet. Using momentum scaling, it was found that the streamwise development of the half-width and maximum mean velocity was independent of the slot Reynolds number.
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| 6. |
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| 7. |
- Abrahamsson, Hans, 1966, et al.
(författare)
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Pulsed Hot-Wire Measurements in Two- and Three-Dimensional Wall Jets
- 1999
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Ingår i: Experiments in Fluids. ; 27, s. 210-218
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Tidskriftsartikel (refereegranskat)abstract
- Pulsed Hot-Wire Anemometry (PHWA) measurements are performed in well defined two- and three-dimensional turbulent wall jets. For the two-dimensional wall jet the objective is to study reported differences between conventional Hot-Wire Anemometry (HWA) and Laser Doppler Anemometry (LDA) results. In the three-dimensional wall jet, new improved data are provided, employing a measuring technique suitable for highly turbulent flows. This, since only hot-wire results previously have been published for this flow. The pulsed wire results show good agreement with existing Laser Doppler anemometer data in the two-dimensional wall jet, both reporting significantly higher turbulence levels in the outer region of the flow than hot-wires do. The hot-wire anemometer errors generally increase with increasing local turbulence intensity and since the three-dimensional wall jet has a higher turbulence level than its two-dimensional equivalent, the new pulsed hot-wire results improve the information available for the turbulence field in this flow significantly.
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| 8. |
- Abrahamsson, Hans, 1966, et al.
(författare)
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Turbulence in a Two-Dimensional Wall-Jet - Experiments and Modeling
- 1992
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Ingår i: 13th Turbulence Conference in Missouri-Rolla..
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Konferensbidrag (refereegranskat)abstract
- An experimental and numerical investigation of the turbulence field in a two-dimensional wall-jet has been carried out in a well-defined geometry. The measurements were performed using a hot-wire technique and the calculations were carried out with a standard k-ε model as well as an algebraic stress model (ASM), using elliptic solvers. For the mean velocity field, good agreements were found between the measurements and the calculations. The measurements of the turbulence intensities reveal two maxima in the stream-wise and span-wise components, while only one maximum was found in the normal component. Also in the shear stress two maxima were found. A comparison between calculations and measurements indicates that improved turbulence models are needed.
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| 9. |
- Abrahamsson, Hans, 1966, et al.
(författare)
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Turbulence Measurements in a Two-Dimensional Wall-Jet
- 1991
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Ingår i: Eight Turbulent Shear Flow Conference, München.
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Konferensbidrag (refereegranskat)abstract
- The high capacity of todays computers has enabled the extension of turbulence models to strongly anisotropic flow fields, i.e. the interest has been focused on the use of the models based on the transport equations for the Reynolds stresses (RST models). To improve these turbulence models well-defined, simple and fundamental experiments are needed, in which gradients of the different turbulence parameters are determined. Together with direct simulations of the Navier-Stokes equations these experiments yield a good base for the improvement of the modelling of different terms in the Reynolds equations. An excellent presentation of the closure problem and the terms of interest for the development of turbulence models has recently been published by Groth (1991). A fundamental, well-defined and simple flow case is the wall-jet, where an interaction between a wall boundary layer and a free shear layer forms the anisotropy as well as the inhomogeneous character of the flow field. A comprehensive literature survey of wall-jets was carried out already in the beginning of the eighties by Launder and Rodi (1980), who studied a large number of more or less well-defined wall-jet experiments. The main conclusion of this survey was a lack of well-defined experiments in simple and fundamental geometries. If the study is limited to the two-dimensional case, a further conclusion from the work of Launder and Rodi was that many of the studied flow cases did not fulfil the condition of two-dimensionality. Although more than ten years have passed since the work of Laundry and Rodi was presented, very few investigations have been reported in which fundamental wall-jets have been studied. Especially well-defined turbulence measurements are needed, since anisotropy of the two-dimensional wall-jet yields a case well suited for the evaluation of e.g. new dissipation models, see Hallbäck et al. (1990). The purpose of the present work was to determine the turbulence field of a two-dimensional wall-jet in a simple and also well-defined geometry without influence of an outer disturbing flow field. To accomplish these measurements was a wall-jet rig used. All turbulence measurements were carried out using hot-wire techniques, single- and cross wires. The measurements presented here were performed at a Reynolds number of ___, based on the slot height and the extensions of the measurements in the flow direction was in the range of x/h=25 through x/h=156 (x-coordinate in the main flow direction and h-slot height).
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| 10. |
- Abu-Gharbieh, Rafeef, 1972, et al.
(författare)
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Compensating Laser Sheet Images of Optically Dense Sprays
- 1999
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Ingår i: Proceedings of the SSAB Conference. Göteborg, Sweden.
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a method for compensating laser attenuation in optically dense sprays, in particular for use in combustion engine research. Images of the fuel sprays are produced by planar laser imaging, where Mie scattered light from a cross section of the spray is imaged onto a CCD camera. The compensation scheme is based on the Beer-Lambert law, which is used here to sum up the loss of light along the path of the laser light in the image, and to compensate iteratively, pixel by pixel, for this loss.
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