| 1. |
- Ayer-LeLievre, C, et al.
(författare)
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Nerve growth factor mRNA and protein in the testis and epididymis of mouse and rat.
- 1988
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 85:8, s. 2628-32
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Tidskriftsartikel (refereegranskat)abstract
- In situ hybridization using beta-nerve growth factor (NGF) DNA probes was used to demonstrate NGF mRNA in spermatocytes and early spermatids of adult mouse. NGF mRNA-containing cells were also identified in the epithelium of convoluted ducts in mouse corpus epididymidis. Blot-hybridization analysis of RNA prepared from mouse testis and epididymis as well as from rat epididymis confirmed the presence of a 1.3-kilobase (kb) NGF mRNA in these tissues. In the rat testis, however, only a 1.5-kb NGF mRNA was found, corresponding in size to a minor NGF mRNA detected in the rat brain, heart, and epididymis. By using affinity-purified anti-NGF antibodies, NGF-like immunoreactivity was observed in germ cells of rat and mouse testis and in the lumen of epididymis. Extracts of both mouse epididymis and testis stimulated fiber outgrowth in cultured sympathetic ganglia, and the effect was blocked by antibodies to mouse NGF. A two-site enzyme immunoassay showed the presence of 10 and 70 ng of NGF per g of tissue in the mouse testis and epididymis, respectively. Furthermore, RNA blot analysis showed the presence of mRNA for the NGF receptor in mouse testis. These results suggest a nonneurotrophic role for NGF in the male reproductive system, possibly in survival maturation and/or motility of spermatozoa.
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| 2. |
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| 3. |
- Ernfors, P, et al.
(författare)
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Developmental and regional expression of beta-nerve growth factor receptor mRNA in the chick and rat.
- 1988
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Ingår i: Neuron. - 0896-6273 .- 1097-4199. ; 1:10, s. 983-96
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Tidskriftsartikel (refereegranskat)abstract
- Hybridization probes from the transmembrane region of the chick NGF receptor (NGF-R) that show high homology with the rat NGF-R were used to demonstrate an abundant 4.5 kb NGF-R mRNA in the chick embryo at E3.5. The level remained high until E12 but decreased to adult levels by E18. The highest levels at E8 were in spinal cord, bursa of Fabricius, gizzard, femoralis muscle, and skin. In situ hybridization to E7 embryos showed high expression of the NGF-R gene in spinal cord, particularly the lateral motor column, and in dorsal root, sympathetic, and nodose ganglia. NGF-R mRNA expression was observed throughout brain development and in all regions of the adult brain, with high levels in cerebellum and septum. Lymphoid tissues of chick and rat also expressed the receptor. The complex and widespread expression of NGF-R mRNA in areas not known to be NGF targets suggests broader functions for NGF.
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| 4. |
- Hallböök, F, et al.
(författare)
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Development and regional expression of chicken neuroleukin (glucose-6-phosphate isomerase) messenger RNA.
- 1989
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Ingår i: Journal of Neuroscience Research. - : Wiley. - 0360-4012 .- 1097-4547. ; 23:2, s. 142-51
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Tidskriftsartikel (refereegranskat)abstract
- Neuroleukin (NLK) is a protein identical with the glycolytic enzyme glucose-6-phosphate isomerase (GPI) that has been reported to support the survival of a subpopulation of neurons in embryonic dorsal root ganglia and spinal cord neurons in culture. In this report we have studied the developmental expression of NLK mRNA in the chick embryo in order to evaluate its possible role as a neurotrophic factor. The chicken gene encoding NLK was isolated by cross-hybridization to a mouse NLK cDNA clone. A DNA fragment from the chicken NLK gene with a 90% nucleotide sequence homology to mouse NLK cDNA encoding amino acids 310-355 was then used as a hybridization probe in a series of RNA-blots. In the entire embryo NLK mRNA was found already at embryonic day 3.5 (E3.5) and the level of expression was significantly decreased between E3.5 and hatching. Roughly similar levels of NLK mRNA were found in all tissues of the E8 embryo analyzed with the exception of the brain, which contained only low levels. When the developmental expression was analyzed in different tissues separately, NLK mRNA expression was found to decrease during development in the heart and bursa of Fabricius, whereas the level of mRNA in the brain showed a large increase shortly after hatching. The spinal cord and the pectoral and femoral muscles all showed high levels of NLK mRNA throughout development. In the adult chick, the highest levels of NLK mRNA were found in the muscle, brain, and kidney, where the NLK mRNA was estimated to account for approximately 0.1% of the total mRNA in these tissues. A widespread expression of NLK mRNA was observed in the adult brain with approximately similar levels in all brain regions tested. Similar results were also obtained when NLK mRNA expression was analyzed in adult rats. Our results show that developmental expression of the NLK gene is independently regulated in different tissues. The widespread and abundant expression of both the avian and rodent NLK gene is in accordance with its newly discovered identity as a glycolytic enzyme. Consequently, the developmental and adult pattern of NLK mRNA expression does not favour a specific trophic role for this protein in accordance with other known neurotrophic factors.
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| 5. |
- Henriksen, O., et al.
(författare)
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In vivo evaluation of femoral blood flow measured with magnetic resonance
- 1989
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 30:2, s. 153-157
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Tidskriftsartikel (refereegranskat)abstract
- Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evalutated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve, corrected for the T2 decay of non-flowing blood was used to calculate the blood flow. As a reference, the blood flow in the femoral artery was measured simultaneously with an invasive indicator dilution technique. T2 of non-flowing blood was measured in vivo in popliteal veins during regional circulatory arrest. The mean T2 of non-flowing blood was found to be 105 ±31 ms. The femoral blood flow ranged between 0 and 643 ml/min measured with MRI and between 280 and 531 ml/min measured by the indicator dilution technique. There was thus poor agreement between the two methods. The results indicate that in vivo blood flow measurements made with MRI based on wash-out effects, commonly used in multiple spin echo imaging, do not give reliable absolute values for blood flow in the femoral artery or vein.
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| 6. |
- Persson, Bengt L., et al.
(författare)
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NBD-Cl modification of essential residues in mitochondrial nicotinamide nucleotide transhydrogenase from beef heart
- 1988
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Ingår i: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology. - : Elsevier BV. - 0167-4838 .- 1879-2588. ; 953, s. 241-248
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Tidskriftsartikel (refereegranskat)abstract
- Modification of mitochondrial nicotinamide nucleotide transhydrogenase (NADPH:NAD+ oxidoreductase, EC 1.6.1.1) with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl), followed by measurement of the absorption or fluorescence of the transhydrogenase-NBD adducts, resulted in a biphasic labelling of approx. 4–6 sulfhydryls, presumably cysteine residues. Of these 1–2 (27%) were fast-reacting and 3–4 (73%) slow-reacting sulfhydryls. In the presence of substrates, e.g., NADPH, the labelling was monophasic and all sulfhydryls were fast-reacting, suggesting that the modified sulfhydryls are predominantly localized peripheral to the NAD(P)(H)-binding sites. The rates of modification allowed the calculation of the rate constants for each phase of the labelling. Both in the absence and in the presence of a substrate, e.g., NADPH, the extent of labelling essentially parallelled the inhibition of transhydrogenase activity. Attempts to reactivate transhydrogenase by reduction of labelled sulfhydryls were not successful. Photo-induced transfer of the NBD adduct in partially inhibited transhydrogenase, from the sulfhydryls to reactive NH2 groups of amino-acid residue(s), identified as lysine residue(s), was parallelled by an inhibition of the residual transhydrogenase activity. It is suggested that a lysine localized close to the fast-reacting NBD-Cl-reactive sulfhydryl groups is essential for activity.
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| 7. |
- Ståhlberg, F., et al.
(författare)
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Determination of flow velocities from magnetic resonance multiple spin-echo images : A phantom study
- 1987
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 28:5, s. 643-648
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to evaluate a method for the quantification of through-plane flow velocities by magnetic resonance imaging (MRI) from the flow characteristics of conventional multiple spin-echo (MSE) signals. Simulated inflow-outflow-dependent signals, as well as images of a flow phantom were generated and the logarithm of the flow-dependent signal value was plotted against echo time. The normalized slope of the resulting curve was calculated using a least-square fit to simulated and experimental data and was corrected for T2 relaxation effects by subtraction of a slope obtained at zero flow. After this correction, and with certain restrictions regarding the flow velocity (v), maximum number of echoes in the slope calculation and slice thickness (L), the normalized slope of the MSE signal becomes equal to the quotient v/L, and from this relation the flow velocity can be determined. The validity of the proposed method was examined for different flow velocities and for two opposite flow directions. The influence of the size of the region of interest and the number of spin echoes used in the calculation of the slope on the accuracy of the velocity determination was also studied. The sensitivity of the method to flow-induced phase changes was examined in the phantom by comparing the results obtained with different strengths of the slice-selective gradient as well as by comparing results from even-echo data with those from odd-echo data. When applied to simulated signal data, the method was found to be strictly valid only for a small velocity range, while for the flow phantom, the calculated velocities corresponded to measured velocities for values up to and over 100 mm/s. In the phantom experiment, the method was found to be insensitive to effects induced by combined changes of the slice thickness and the slice-selective gradient as well as to so-called even-echo rephasing effects. It is concluded that the examined method promises to be a rapid and easily interpretable alternative to other methods, e.g. magnetic resonance velocity-phase encoding, for the determination of flow velocities in vivo.
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| 8. |
- Ståhlberg, F., et al.
(författare)
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Method for quantification of low flow velocities by magnetic resonance phase imaging.
- 1986
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Ingår i: Acta Radiologica. Supplementum. - 0365-5954. ; 369, s. 486-489
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare the influence of flow in the velocity range 0 to 25 mm/s on modulus, phase, real and imaginary images obtained with a standard magnetic resonance scanner (Siemens Magnetom, 0.5 T), and to develop a simple method for determination of flow velocities in vivo from this information. Using a flow phantom, the flow dependent magnetic resonance imaging (MRI) signal has been studied as a function of flow perpendicular to the image slice with non-doped water (simulating moving cerebrospinal fluid) as well as with water doped with Mn2+ (simulating moving blood) for each of the four mentioned image types. The results show a marked flow dependence on all types of images studied. The variation of the signal with flow in the modulus images is relaxation-time dependent in the studied velocity range and it is non-monotone for non-doped water. In the phase images, however, the variations are monotone and not dependent on relaxation times. In modulus images the curve shape is relatively independent on flow direction, while phase images are clearly dependent on flow direction in the studied velocity range. The signal versus velocity curves for the real and imaginary images show resemblance to those for the modulus and the phase images, respectively. It is concluded that the phase information can be used to generate a signal versus velocity calibration curve, which can be used to quantify low flow velocities in vivo.
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