| 1. |
- Nilsson, C, et al.
(author)
-
Circadian variation in human cerebrospinal fluid production measured by magnetic resonance imaging
- 1992
-
In: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. - 1522-1490. ; 262:1, s. 20-24
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Journal article (peer-reviewed)abstract
- Recent advances in magnetic resonance imaging have made it possible to visualize and quantify flow of cerebrospinal fluid (CSF) in the brain. The net flow of CSF through the cerebral aqueduct was used to measure CSF production in six normal volunteers at different times during a 24-h period. CSF production varied greatly both intra- and interindividually. The average CSF production in each time interval showed a clear tendency to circadian variation, with a minimum production 30% of maximum values (12 +/- 7 ml/h) approximately 1800 h and a nightly peak production approximately 0200 h of 42 +/- 2 ml/h. The total CSF production during the whole 24-h period, calculated as an average of all measurements, was 650 ml for the whole group and 630 ml for repeated measurements in each time interval in one of the volunteers.
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| 2. |
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| 3. |
- Ahrén, K, et al.
(author)
-
Histamine stimulates progesterone synthesis and cyclic adenosine 3',5'-monophosphate accumulation in isolated preovulatory rat follicles
- 1987
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In: Neuroendocrinology. - : S. Karger AG. - 0028-3835 .- 1423-0194. ; 46:1, s. 69-74
-
Journal article (peer-reviewed)abstract
- The effect of histamine on progesterone synthesis and cyclic adenosine 3',5'-monophosphate (cAMP) accumulation was studied in superfused and incubated follicles dissected free from immature rats treated with pregnant mare serum gonadotrophin (PMSG). Histamine, like LH, increased the progesterone synthesis, but to a smaller extent. The H2-antagonist, cimetidine, inhibited completely the histamine-induced progesterone increase while the H1-antagonist, pyrilamine, as well as propranolol and atropine did not affect the initial response but modified its duration. The specific H2-agonist, 4-methylhistamine, but not the H1-agonist, 2-methylhistamine, mimicked the effect of histamine on progesterone synthesis. In the presence of the phosphodiesterase inhibitor, IBMX, histamine increased tissue levels of cAMP. These results suggest that histamine stimulates progesterone synthesis via the H2-receptor with cAMP acting as secondary intracellular messenger.
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| 4. |
- Blay, P, et al.
(author)
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Transthyretin expression in the rat brain: effect of thyroid functional state and role in thyroxine transport
- 1993
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In: Brain Research. - 1872-6240. ; 632:1-2, s. 114-120
-
Journal article (peer-reviewed)abstract
- Rats were made hypo- or hyperthyroid to study the role of thyroid hormones on cerebral transthyretin (TTR) mRNA expression. TTR mRNA was detected by Northern blot in rat liver, choroid plexus and meninges but not in cultured astrocytes or cultured cerebral endothelial cells. No changes were found in the levels of TTR mRNA in liver, choroid plexus or meninges in hypo- or hyperthyroid rats compared with the controls. In order to investigate the main route of thyroxine transport from blood to brain, the distribution of [125I]thyroxine in the brain was studied after intravenous (i.v.) and intraventricular (i.v.c.) injection by both direct counting and autoradiography. While distribution of [125I]thyroxine could be seen throughout the brain parenchyma after i.v. injection, the labelling was confined to the CSF spaces after i.v.c. administration. When protein synthesis was inhibited by cycloheximide treatment and [125I]thyroxine was injected intravenously, the uptake of [125I]thyroxine in the choroid plexus decreased while the uptake in the cerebral cortex increased. This indicates that thyroxine is transported into the brain primarily through the blood-brain barrier and not via the choroid plexus and CSF. We discuss the possibility that TTR has a role in the distribution of thyroxine throughout the brain.
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| 5. |
- Bodelsson, Mikael, et al.
(author)
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Cooling enhances alpha 2-adrenoceptor-mediated vasoconstriction in human hand veins
- 1990
-
In: Acta Physiologica Scandinavica. - 0001-6772. ; 138:3, s. 283-291
-
Journal article (peer-reviewed)abstract
- The contribution of different receptor subtypes in the contractile response during cooling in human hand vessels is of considerable interest in the understanding of cold-induced peripheral vasospasm as it appears in Raynaud's phenomenon. Subcutaneous vein segments from 50 patients undergoing hand operations not related to vascular disorders were examined in vitro. The temperature in the organ bath was initially 37 degrees C and was either continuously lowered to 10 degrees C or kept constant at 37 degrees C, 29 degrees C or 20 degrees C. The characteristics of the alpha-adrenoceptor-mediated motor response were elucidated with the use of the alpha 1-antagonist, prazosin, and the alpha 2-antagonist, yohimbine. A great variability between individuals in the proportions of alpha 1- and alpha 2-adrenoceptors was found. In the majority of the vessels continuous cooling to 25 degrees C augmented a noradrenaline-induced contraction. This augmentation was unaltered in the presence of prazosin but abolished by yohimbine, suggesting that it was mediated via the alpha 2-adrenoceptor. In the remaining vessels with a predominating alpha 1-adrenoceptor-mediated response a cold-induced relaxation was registered. This could be the result of a reduced alpha 1-adrenoceptor-mediated contraction at this low temperature. These varying reactions to cooling were unaffected by the beta-antagonist, propranolol, and by endothelial denudation. The results obtained in corresponding experiments with the alpha 1-agonist methoxamine and alpha 2-agonist, oxymetazoline, were conflicting, probably due to the poor selectivity of these agonists in human tissues.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 6. |
- Emilsson, K, et al.
(author)
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Vascular effects of proteinase-activated receptor 2 agonist peptide
- 1997
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In: Journal of Vascular Research. - 1423-0135. ; 34:4, s. 267-272
-
Journal article (peer-reviewed)abstract
- Proteinase-activated receptor 2 (PAR-2) is a G protein-coupled receptor related to the thrombin receptor. PAR-2 can be activated by trypsin and by synthetic peptides corresponding to the new amino terminus generated by activating proteolytic cleavage. We show in this report that intravenous injection of PAR-2 agonist peptides has dramatic effects on arterial blood pressure in anesthetized rats. The peptide SLIGRLETQPPI, at 150 nmol/kg, transiently decreased the mean arterial pressure from 104 to 60 mm Hg. The hypotensive response was dose-dependent, and was not secondary to effects on central vasoregulatory systems, heart rate, or the kidneys. A nitric oxide synthase inhibitor attenuated the hypotensive response induced by the PAR-2 agonist peptide. Further experiments in vitro, on preparations of rat femoral artery and vein, showed that PAR-2 agonist peptide elicited a dose-dependent relaxation of both types of vessel. Removal of the endothelium abolished the agonist peptide-induced relaxation. Our results demonstrate that activation of PAR-2 can modulate vascular tone, and that this response was an effect mediated at least partly by nitric oxide. The effect on blood vessels further suggests that the physiological activator of this proteolytically activated receptor is an enzyme present and active in the blood, possibly after a vascular injury.
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| 7. |
- Freedman, J, et al.
(author)
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Vasoconstrictor effects in spinal cord of the substance P antagonist [D-Arg, D-Trp7,9 Leu11]-substance P (Spantide) and somatostatin and interaction with thyrotropin releasing hormone
- 1988
-
In: Neuroscience. - : Elsevier BV. - 1873-7544 .- 0306-4522. ; 27:1, s. 267-278
-
Journal article (peer-reviewed)abstract
- The present study was undertaken to investigate the possible effects of Spantide [D-Arg1, D-Trp7,9 Leu11]-substance P, a substance P antagonist, and of somatostatin on spinal cord blood flow. The experiments were performed with the laser-doppler technique on the L1 spinal cord segment exposed by laminectomy. The effect of Spantide was also studied in the rat with the [14C]iodoantipyrine technique. In addition, experiments were performed on rabbit skeletal muscle in vivo after administration of Spantide to the local vasculature. In the experiments on spinal cord, approximately the same doses were employed as those earlier shown to be "neurotoxic". When the vehicle alone (0.9% saline) was administered intrathecally, a slight decrease of brief duration was noted in the blood flow. Spantide, however, caused a dose-dependent decrease, where 2 micrograms caused an immediate drop of the blood flow to approx. 20% of its normal value. A total circulatory arrest was found in several animals. In most cases, the flow was gradually normalized, whereas the effect persisted for up to 60 min in others. Virtually the same effect was exerted by somatostatin. The experiments using the iodoantipyrine technique confirmed the effect of Spantide. Here, the high resolution of this method showed that the gray matter was affected preferentially, with a complete ischemic state or a drastically reduced flow in 4 out of 5 animals 10 min after 2 micrograms of Spantide; one animal was unaffected, and this animal did not show any signs of motor impairment. The vasoconstriction of Spantide was not affected by simultaneous injections with substance P. However, after i.v. pretreatment with thyrotropin-releasing hormone, at a dose that previously has been reported to be protective against the neurodegenerative effects of Spantide, blood flow was markedly increased as compared to Spantide alone. Results from the experiments using intravital microscopy flow studies in the rabbit tenuissimus muscle revealed that Spantide at the doses used had no vasoconstrictor effect in the skeletal muscle of this species. The results suggest that previous demonstrations of motor impairment and "neurotoxic" actions of intrathecally injected substance P antagonists and somatostatin may be related to a marked decrease in spinal cord blood flow. Counteraction of the effect of Spantide by thyrotropin-releasing hormone may be explained by its effect to increase blood flow.
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| 8. |
- Hansson, Boel, et al.
(author)
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MR-safety: Evaluation of compliance with screening routines using a structured screening interview
- 2022
-
In: Journal of Patient Safety and Risk Management. - : SAGE Publications. - 2516-0435 .- 2516-0443. ; 27:2, s. 76-82
-
Journal article (peer-reviewed)abstract
- Background Magnetic resonance (MR) safety procedures are designed to allow patients, research subjects and personnel to enter the MR-scanner room under controlled conditions and without the risk to be harmed during the examination. Ferromagnetic objects in the MR-environment or inside the human body represent the main safety risks potentially leading to human injuries. Screening for MR-safety risks with dedicated procedures is therefore mandatory. As human errors during the screening procedure might align and lead to an incident compliance is essential. Purpose To evaluate compliance with a documented structured MR-safety screening process. Method Written and signed MR-safety screening documentation collected at a national 7T MR facility during a four-year period was evaluated for compliance of trained personnel with multi-step MR-safety routines. We analysed whether examinations were performed or why they were not performed. Data analysis further included descriptive statistics of the study population (age, gender and patient or healthy volunteer status), identification of missing documents and omitted or incorrect answers, and whether these compliance shortcomings concerned predominantly administrative or MR-safety related issues. Results Documentation of the screening process in 1819 subjects was incomplete in 19% of subjects. The most common documentation shortcoming was omitted fields. Out of 478 omitted answer-fields in 307 subjects, 36% were of administrative nature and 64% related directly to MR-safety issues. Conclusion Compliance with MR-safety screening procedures cannot be taken for granted and deficiencies to comply with screening routines were revealed. Documentation shortcomings concerned both administrative and MR-safety related issues.
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| 9. |
- Hansson, B., et al.
(author)
-
MR-safety in clinical practice at 7T: Evaluation of a multistep screening process in 1819 subjects
- 2022
-
In: Radiography. - : Elsevier BV. - 1078-8174. ; 28:2, s. 454-459
-
Journal article (peer-reviewed)abstract
- Introduction: MR facilities must implement and maintain adequate screening and safety procedures to ensure safety during MR examinations. The aim of this study was to evaluate a multi-step MR safety screening process used at a 7T facility regarding incidence of different types of safety risks detected during the safety procedure. Methods: Subjects scheduled for an MR examination and having entered the 7T facility during 2016–2019 underwent a pre-defined multi-step MR safety screening process. Screening documentation of 1819 included subjects was reviewed, and risks identified during the different screening steps were compiled. These data were also related to documented decisions made by a 7T MR safety committee and reported MR safety incidents. Results: Passive or active implants (n = 315) were identified in a screening form and/or an additional documented interview in 305 subjects. Additional information not previously self-reported by the subject, regarding implants necessitating safety decisions performed by the staff was revealed in the documented interview in 102 subjects (106 items). In total, the 7T MR safety committee documented a decision in 36 (2%) of the included subjects. All of these subjects were finally cleared for scanning. Conclusion: A multi-step screening process allows a thorough MR screening of subjects, avoiding safety incidents. Different steps in the process allow awareness to rise and items to be detected that were missed in earlier steps. Implications for practice: Safety questions posed at a single timepoint during an MR screening process might not reveal all safety risks. Repetition and rephrasing of screening questions leads to increased detection of safety risks. This could be effectively mitigated by a multi-step screening process. A multi-disciplinary safety committee is efficient at short notice responding to unexpected safety issues. © 2021 The Author(s)
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| 10. |
- Johansson, L.I., et al.
(author)
-
Electronic structure of 6H-SiC(0001)
- 1996
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In: Physical Review B (Condensed Matter). - 0163-1829. ; 53:20, s. 13803-13807
-
Journal article (peer-reviewed)
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| 11. |
- Kahrstrom, J, et al.
(author)
-
A morphometric study of the effect of bilateral cervical sympathetic ganglionectomy on the architecture of pial arteries in spontaneously hypertensive and normotensive rats
- 1994
-
In: Acta Physiologica Scandinavica. - 0001-6772. ; 152:4, s. 407-418
-
Journal article (peer-reviewed)abstract
- The influence of the cranial sympathetic nerves on the architecture of pial arteries in normo- and hypertension was examined. For this purpose the effect of bilateral superior cervical ganglionectomy was evaluated in normotensive rats (WKY) and stroke-prone spontaneously hypertensive rats (SHRSP). The operations were performed at the age of 1 wk, which is just prior to the onset of ganglionic transmission. The length of the inner media contour was measured and the media cross-sectional area was determined planimetrically, with computerized digitalization of projected photographic images of transversely sectioned pial arteries. Four wk after sympathectomy there was a 20% reduction in media cross-sectional area and a consequent reduction in the ratio between media area and calculated luminal radius in the major pial arteries at the base of the brain in WKY but not in SHRSP. Conversely, in small pial arteries linear regression analysis showed that in WKY subjected to ganglionectomy the relationship between media cross-sectional area and luminal radius was significantly larger in arteries with a radius less than 21 microns compared to untreated WKY. No such effect was seen in the corresponding SHRSP vessels. In addition, the cross-sectional area of the internal elastic membrane (IEM) in the basilar arteries of WKY was measured by means of a computerized image-analysing system. Mean cross-sectional area of the IEM was approximately 45% larger following SE than in control animals. The present findings propose a 'trophic' role for the sympathetic perivascular nerves in large pial arteries of the rat. The increased media-radius ratio in the small pial arteries of the WKY following sympathectomy might reflect a compensatory hypertrophy due to reduced protection from the larger arteries against the pressure load. The inability to detect any morphometrically measurable effect of the sympathectomy in the cerebral arteries of SHRSP is probably explained by a marked growth-stimulating effect of the high pressure load in these animals.
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| 12. |
- Kannisto, P, et al.
(author)
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Characterization of presynaptic 5-HT receptors on adrenergic nerves supplying the bovine ovarian follicle
- 1987
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In: British Journal of Pharmacology. - : Wiley. - 0007-1188. ; 92:3, s. 97-487
-
Journal article (peer-reviewed)abstract
- 1. The effects of 5-hydroxytryptamine (5-HT) on contraction and release of [3H]-noradrenaline were investigated in vitro in bovine ovarian follicle strips. Using available selective agonists and antagonists, an effort was made to characterize the type of receptor mediating the inhibitory effect of 5-HT on neurogenic contraction and release of [3H]-noradrenaline by electrical field stimulation. 2. 5-Hydroxytryptamine inhibited the neurogenic contraction and release of [3H]-noradrenaline evoked by electrical field stimulation in a concentration-dependent manner. Like 5-HT, 5-carboxamidotryptamine (5-CT) and methysergide reduced the transmitter release as well as the neurogenic contraction, whereas 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) failed to inhibit both responses in concentrations up to 0.1 microM. 3. The 5-HT (1 microM)-induced inhibition of contractile responses was more evident during stimulation at low frequencies (4 and 8 Hz) than during high frequency electrical stimulation (16 and 32 Hz). 4. Methiothepin (1 microM) and methysergide (10 microM) significantly antagonized the inhibitory effect of 5-HT on the electrically evoked release of tritium, whereas cyanopindolol, MDL 72222 and ketanserin (all 0.1 microM) were without effect. In addition, ketanserin, MDL 72222, cimetidine, pyrilamine, atropine, propranolol and indomethacin were without effect on the 5-HT-induced inhibition of the neurogenic contraction. 5. It is suggested that 5-HT inhibits the electrically evoked transmitter release from adrenergic nerves in the bovine ovarian follicle wall via prejunctional 5-HT1-like receptors. This was based on the findings that 5-CT was a potent agonist, methiothepin an antagonist and the lack of effect of MDL 72222, cyanopindolol and ketanserin.
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| 13. |
- Kannisto, P, et al.
(author)
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Evidence for prejunctional GABAB receptors mediating inhibition of ovarian follicle contraction induced by nerve stimulation
- 1986
-
In: European Journal of Pharmacology. - : Elsevier BV. - 0014-2999. ; 122:1, s. 9-123
-
Journal article (peer-reviewed)abstract
- The motor effects of gamma-aminobutyric acid (GABA) on the bovine ovarian follicle were studied in vitro using strips from follicle walls. Electrical field stimulation of nerves in the preparation, secured by tetrodotoxin blockade, caused a contraction that was almost totally abolished by phentolamine and only slightly affected by atropine. This mainly adrenergic neurogenic response was inhibited by GABA in a dose-dependent way. The GABAA-receptor antagonists, bicuculline and picrotoxin, did not affect the GABA action whereas the GABAB-receptor antagonist, homotaurine, significantly inhibited the GABA effect. The GABAA-receptor agonist, muscimol, did not affect the contractile response while the GABAB-receptor agonist, baclofen, imitated the action of GABA. On the other hand, GABA had no direct contractile or relaxing effect on the follicle strips nor did it interfere with the contractile response induced by noradrenaline or acetylcholine. The findings suggest that activation of prejunctional GABAB receptors inhibits transmitter release from mainly adrenergic nerves associated with the follicle, thereby affecting nerve-mediated tension in the follicle wall.
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| 14. |
- Kannisto, P, et al.
(author)
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Existence and coexistence of peptides in nerves of the mammalian ovary and oviduct demonstrated by immunocytochemistry
- 1986
-
In: Histochemistry. - : Springer Science and Business Media LLC. - 0301-5564 .- 1432-119X. ; 86:1, s. 25-34
-
Journal article (peer-reviewed)abstract
- The immunocytochemical distribution of substance P (SP), gastrin releasing peptide (GRP), vasoactive intestinal polypeptide (VIP), peptide histidine isoleucine (PHI), and neuropeptide Y (NPY) was studied in the ovary and the Fallopian tube (oviduct) of rats, guinea-pigs, cows, pigs and humans. Generally, the nerve supply was better developed in the oviduct than in the ovary. GRP fibers were most scarce in all tissues. Nerves containing SP were particularly numerous in the oviduct of rat and guinea-pig, supplying the muscular wall and blood vessels. VIP and PHI coexisted in dense plexuses of nerves, not only around blood vessels but also in the follicular wall and the interstitial gland of the ovary, as well as within the smooth muscle layers and subepithelially in the oviduct. The general distribution of NPY was similar, but these immunoreactive nerves were even more numerous. Sequential staining for dopamine-beta-hydroxylase and NPY together with results of chemical sympathectomy with 6-hydroxydopamine suggested that NPY was stored in the noradrenergic sympathetic nerves.
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| 15. |
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| 16. |
- Kannisto, P, et al.
(author)
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Intraovarian adrenergic nerves in the guinea-pig : development from fetal life to sexual maturity
- 1984
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In: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 238:2, s. 40-235
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Journal article (peer-reviewed)abstract
- The development of the intraovarian adrenergic nervous system was investigated in the guinea-pig by use of chemical determination of catecholamines with high performance liquid chromatography (HPLC) and with the formaldehyde-induced fluorescence method for visualization of adrenergic nerves (Falck-Hillarp technique). Ovaries from fetuses (39-40, 45-50, 55-57, 60-63 days of gestation) and young animals (1, 2, 3, 7, 14, 30, 40-45 days of age) were included in the study. The noradrenaline concentration was low in the ovaries from the youngest fetuses but increased with age, reaching a maximum level at 2 days post partum. A marked decrease in noradrenaline concentration from the second to the third day of life was found as a consequence of the rapid increase in the ovarian weight during this time. A similar decrease in ovarian noradrenaline concentration after a period of rapid ovarian growth was noted at 30 days of age. Measurable amounts of adrenaline were found in the ovary only in the fetal stages; the highest concentration (0.73 microgram) was detected at 55-57 days of gestation.
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| 17. |
- Kannisto, P, et al.
(author)
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Involvement of local adrenergic receptors in the process of ovulation in gonadotrophin-primed immature rats
- 1985
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In: Journal of Reproduction and Fertility. - : Bioscientifica. - 0022-4251. ; 75:2, s. 62-357
-
Journal article (peer-reviewed)abstract
- Immature female rats were primed with 4 i.u. PMSG at 08:00 h of Day 26. This results in ovulation in the morning of Day 29. The number of ovulations was counted in terms of newly formed corpora lutea in the morning of Day 30. Various adrenergic drugs were delivered into the ovarian bursa bilaterally in the afternoon of Day 27 to study their effect on ovulation. A methyl cellulose gel solution was used as vehicle to minimize leakage from the bursa. Noradrenaline, terbutaline and 4-aminopyridine significantly enhanced the number of corpora lutea compared to control ovaries injected with gel vehicle alone. The effect of terbutaline was counteracted by propranolol. Phentolamine partly blocked the noradrenaline-induced enhancement and the antagonist alone significantly reduced the number of ovulations. The results indicate that stimulation of alpha-adrenergic receptors (probably via actions in the follicle wall) as well as beta-receptors (influencing steroid-producing cells) may interfere with the ovulation process.
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| 18. |
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| 19. |
- Kull, B, et al.
(author)
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Differences in the order of potency for agonists but not antagonists at human and rat adenosine A2A receptors
- 1999
-
In: Biochemical Pharmacology. - 0006-2952. ; 57:1, s. 65-75
-
Journal article (peer-reviewed)abstract
- To examine possible species differences in pharmacology, rat adenosine A2A receptors were studied in PC12 (pheochromocytoma) cells, and human receptors in Chinese hamster ovary (CHO) cells transfected with the cloned human A2A receptor cDNA. Using [3H]-5-amino-7(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo [1,5-c]pyrimidine ([3H]-SCH 58261) as radioligand, the estimated Bmax (maximal binding) was 538 and 2085 fmol/mg in CHO and PC12 cells, respectively. The Kd (dissociation constant) values for [3H]-SCH 58261 were 1.05 and 5.6 nM in the two cell types, respectively. The order of potency of antagonists and most agonists was the same in both cell types, but 2-phenylaminoadenosine and 2-chloroadenosine were relatively less potent in PC12 cells than in CHO cells. In the functional assay, using cyclic AMP accumulation, all agonists tested were more potent in CHO than in PC12 cells, but this could not be readily explained by differences in adenylyl cyclase or in the expression of G proteins. As in the case of binding, the relative agonist potencies were similar for most compounds, but 2-phenylaminoadenosine and 2-chloroadenosine were more potent at human A2A receptors in CHO cells than predicted from the data obtained on rat A2A receptors in PC12 cells. Antagonists were approximately equipotent in the two cells. These results show that, despite only small differences in amino acid sequences and no difference in antagonist pharmacology, the relative order of potency of receptor agonists can differ between species homologues of the adenosine A2A receptor.
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| 20. |
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| 21. |
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| 22. |
- Kåhrström, J, et al.
(author)
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Neonatal pre-ganglionic sympathectomy affects morphometrically defined architecture in rat cerebral arteries
- 1996
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In: Acta Physiologica Scandinavica. - 0001-6772. ; 157:2, s. 225-231
-
Journal article (peer-reviewed)abstract
- In order to clarify further the nature of the long-term influence on the cerebral vasculature by the sympathetic nerves, a bilateral cervical pre-ganglionic denervation was performed in 1-week-old rats. Four weeks later, morphometric determinations of the vascular dimensions revealed diminished media cross-sectional areas and luminal radii in the middle cerebral and posterior cerebral arteries, whereas these parameters were unaffected in the basilar artery. In the latter artery, however, a 40% increase in the cross-sectional area of the internal elastic membrane was found. No re-innervation of the denervated ganglia occurred during the course of the experiment. The results suggest that the long-term effect exerted by the sympathetic nerves is associated with the nerve activity, rather than being a true trophic influence.
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| 23. |
- Lindahl, Sture, et al.
(author)
-
Powerformer™: A giant Step in Power Plant Engineering
- 1999
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In: [Host publication title missing].
-
Conference paper (peer-reviewed)abstract
- Powerformer(R), a new high-voltage generator, was presented by ABB. It offers a direct connection to the power network without the need for a step-up transformer. In a sense, Powerformer incorporates into one unit the functions of both the conventional generator and the step-up transformer. Thanks to its ability to generate electricity at transmission voltage levels, a power plant utilizing Powerformer offers considerable gains with respect to reactive power production and plant efficiency. Thus, Powerformer both facilitates network stability and decreases the exploitation of the natural resources
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| 24. |
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| 25. |
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| 26. |
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| 27. |
- Nilsson, C, et al.
(author)
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Simultaneous and continuous measurement of choroid plexus blood flow and cerebrospinal fluid production: effects of vasoactive intestinal polypeptide
- 1991
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In: Journal of Cerebral Blood Flow and Metabolism. - 1559-7016. ; 11:5, s. 861-867
-
Journal article (peer-reviewed)abstract
- Using laser-Doppler flowmetry during ventriculocisternal perfusion with inulin-[14C]carboxylic acid, choroid plexus blood flow (CPBF) and CSF production were measured simultaneously in rats during periods of 3 h. Blood flow and CSF production decreased only slightly during control experiments. The effect of vasoactive intestinal polypeptide (VIP) was studied at different concentrations of the peptide given either intraventricularly or intravenously. Intraventricular administration of VIP (10(-9) or 10(-7) M) resulted in a decrease in CSF production of up to 30%, while CPBF increased by 20%, also demonstrating that CSF production and blood flow are not directly coupled in the choroid plexus. When infused intravenously, VIP (10 or 100 pmol/kg/min) increased CPBF, an effect partly antagonized at higher concentrations owing to a VIP-induced systemic hypotension. No effect of VIP on CSF production could be seen with intravenous administration.
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| 28. |
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| 29. |
- Owman, C, et al.
(author)
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Comparative histochemical distribution of nerve fibres storing noradrenaline and neuropeptide Y (NPY) in human ovary, fallopian tube, and uterus
- 1986
-
In: Medical Biology. - 0302-2137. ; 64:2-3, s. 57-65
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Journal article (peer-reviewed)abstract
- Nerves containing noradrenaline were studied by formaldehyde-induced fluorescence and neuropeptide Y (NPY) was visualised by immunohistochemistry in the human ovary, Fallopian tube and uterus. All structures were richly supplied with noradrenergic fibres closely associated with the vascular and non-vascular smooth musculature. NPY-containing nerve terminals were consistently fewer, particularly in the ovary. The best developed nerve supply was found in the tubal isthmus and uterine cervix. Vessels were usually innervated by plexuses of nerves, containing NPY as well as noradrenaline. The discrepancy between the number of the two types of histochemically distinguishable nerves suggests that, if noradrenaline and NPY are co-localised in one and the same nerve, this is not a constant phenomenon in the human female reproductive tract.
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| 30. |
- Owman, Christer, et al.
(author)
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Method for identifying ligands activating either excitatory or inhibitory G-protein-coupled receptors by functional coexpression in Xenopus oocytes
- 1997
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In: Biochemical and Biophysical Research Communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 233:3, s. 853-856
-
Journal article (peer-reviewed)abstract
- Xenopus oocytes devoid of their follicular enclosure provide a frequently used expression system for investigating receptors that transduce through activation of adenylyl cyclase following injection of the appropriate mRNA. However, due to a low basal activity of the cyclase they cannot be utilized to investigate receptor-mediated reductions in endogenous cAMP levels. In order to overcome this limitation, a model was designed in which test clones for such inhibitory receptors were co-expressed with a beta 2-adrenoceptor, which elevated cAMP upon exposure to isoproterenol. Following injection of mRNA to express the alpha 2 test receptor in the oocytes, marked reduction in cAMP could be measured after exposure to clonidine. Attenuation of cAMP levels was also seen following co-expression of the dopamine D2 receptor along with dopamine administration. Thus, after inducing a receptor-mediated tone in adenylyl cyclase activity, Xenopus oocytes can be conveniently used to study also ligands that bind to inhibitory G-protein coupled receptors.
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| 31. |
- Owman, Christer, et al.
(author)
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The leukotriene B4 receptor functions as a novel type of coreceptor mediating entry of primary HIV-1 isolates into CD4-positive cells
- 1998
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In: Proceedings of the National Academy of Sciences. - 1091-6490. ; 95:16, s. 9530-9534
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Journal article (peer-reviewed)abstract
- The recently cloned human chemoattractant receptor-like (CMKRL)1, which is expressed in vivo in CD4-positive immune cells, has structural homology with the two chemokine receptors C-C chemokine receptor (CCR)5 and C-X-C chemokine receptor (CXCR)4, which serve as the major coreceptors necessary for fusion of the HIV-1 envelope with target cells. In view of the structural similarity, CMKRL1 was tested for its possible function as another HIV-1 coreceptor after stable expression in murine fibroblasts bearing the human CD4 receptor. The cells were infected with 10 primary clinical isolates of HIV-1, and entry was monitored by semiquantitative PCR of viral DNA. The efficiency of the entry was compared with the entry taking place in CD4-positive cells expressing either CCR5 or CXCR4. Seven of the isolates used CMKRL1 for viral entry; they were mainly of the syncytium-inducing phenotype and also used CXCR4. Entry efficiency was higher with CMKRL1 than with CXCR4 for more than half of these isolates. Three of the ten isolates did not use CMKRL1; instead, entry was mediated by both CCR5 and CXCR4. The experiments thus indicate that CMKRL1 functions as a coreceptor for the entry of HIV-1 into CD4-positive cells. In the course of this study, leukotriene B4 was shown to be the natural ligand for this receptor (now designated BLTR), which therefore represents a novel type of HIV-1 coreceptor along with the previously identified chemokine receptors. BLTR belongs to the same general chemoattractant receptor family as the chemokine receptors but is structurally more distant from them than are any of the previously described HIV-1 coreceptors.
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| 32. |
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| 33. |
- Sahlin, C, et al.
(author)
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Changes in contractile response and effect of a calcium antagonist, nimodipine, in isolated intracranial arteries of baboon following experimental subarachnoid hemorrhage
- 1990
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In: Brain Research Bulletin. - 0361-9230. ; 24:3, s. 355-361
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Journal article (peer-reviewed)abstract
- Isolated pial arteries from a previously well-characterized model of experimental subarachnoid hemorrhage (SAH) in baboon were tested for their contractile response to 5-hydroxytryptamine (5-HT), norepinephrine (NE), and prostaglandin F2 alpha (PGF2 alpha) and the effect of the calcium antagonist, nimodipine. Autologous blood was injected cisternally at three times with one-day intervals to a total amount of 11.5-29.5 ml (mean: 18.5 ml), and the animals were killed 7 days after the first injection. Untreated animals served as controls. The degree of maximum contraction (EAm) with 5-HT and NE in the control situation was for the three arteries tested in the order middle cerebral greater than anterior cerebral greater than basilar artery. Experimental SAH markedly increased EAm, by 190-370 percent above control values (depending on type of vessel) for 5-HT and 170-185 percent for NE. In addition, the sensitivity to 5-HT was significantly increased, as evidenced by a left-shift of the concentration-response curve. Previous exposure of the artery to 10(-6) M nimodipine reduced the contractile response of both amines to approximately half, the inhibition being slightly less pronounced post-SAH. When vessels were contracted beforehand with the amines or with PGF2 alpha, followed by administration of increasing amount of nimodipine (10(-9) M to 10(-6) M), a concentration-dependent relaxation was obtained by up to 60 percent of the original level. This relaxing effect was significantly less following SAH in the experiments with NE and PGF2 alpha compared to 5-HT; the contraction in the presence of 5-HT did not differ before and after experimental SAH. The experiments show that SAH markedly enhances the intrinsic activity for both 5-HT and NE. Nimodipine inhibits the contractile response less efficiently following experimental SAH. The difference in the responsiveness to 5-HT on the one hand, and to NE and PGF2 alpha on the other, could be due to differences in the blood-induced alterations of those calcium channels that are influenced by the calcium antagonist, nimodipine.
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| 34. |
- Schmidt, Gunther, et al.
(author)
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Alteration by histamine of the sympathetic nerve-mediated contractions in the bovine ovarian follicle wall in vitro
- 1987
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In: European Journal of Pharmacology. - : Elsevier BV. - 0014-2999. ; 135:1, s. 11-22
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Journal article (peer-reviewed)abstract
- The histaminergic effect on electrically induced contractions and tritium release was studied in vitro, using strips from the wall of mature bovine ovarian follicles. Follicular fluid and blood plasma from the animals were analysed for electrolyte, bicarbonate, glucose and total protein concentrations in order to compare them with the concentrations of these components in the Krebs-Ringer solution used in the experiments. Electrical field stimulation (EFS) of the follicle strip caused a contraction which was completely blocked by tetrodotoxin and was predominantly of adrenergic origin since phentolamine, in contrast to atropine, blocked the response. The neurogenic response was inhibited by histamine in a concentration-dependent way via the H1-receptor since the H1-antagonist, pyrilamine, counteracted the inhibitory effect of histamine while the H2-antagonist, cimetidine, potentiated the effect. This histaminergic response of EFS-induced contractions could be reproduced in experiments where the H1-agonist, 2-methylhistamine, was inhibitory while the H2-agonist, 4-methylhistamine, had no obvious influence on the twitch response. Histamine reduced the contractile response to exogenous noradrenaline via the H1-receptor, because pyrilamine counteracted, and cimetidine potentiated the effect. The histamine-induced depression of the motor response to EFS and exogenous noradrenaline was probably due to a postjunctional effect mediated by the H1-receptor. Experiments utilizing [3H]noradrenaline release during EFS did not suggest prejunctional effects of histamine. Chemical determinations on follicle fluid and plasma showed that the artificial follicular fluid imitated well the environmental conditions the follicle wall is exposed to in situ.
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| 35. |
- SCHMIDT, G., et al.
(author)
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Is serotonin involved in the ovulatory process of the rat ovary perfused in vitro?
- 1988
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In: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 132:2, s. 251-256
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Journal article (peer-reviewed)abstract
- The presence of 5‐HT (serotonin) in ovarian tissue and its varying concentrations during the oestrous cycle suggests that it takes part in ovarian function and in the ovulatory process as one of several mediators of the inflammatory‐type reaction preceding follicular rupture. With the aid of a recirculating perfusion model, in which the central stimulatory action of 5‐HT was avoided, its direct ovarian effect on ovulation was studied using immature, pregnant, mare serum gonadotrophin (PMSG)‐treated rats. Four out of five ovaries ovulated after the addition of 5‐HT to the perfusion medium, though the ovulation rate (0.8 per ovary) did not reach the order of magnitude seen after luteinizing hormone (LH) stimulation (5.4 per ovary). The selective 5‐HT2 receptor antagonist, ketanserin, did not signficantly reduce the 5‐HT induced ovulations. The nonselective 5‐HT receptor antagonist, methysergide, blocked the 5‐HT induced ovulations, and moreover, reduced the LH‐stimulated ovulations. The calcium entry blocker, nifedipine, had no effect on either 5‐HT or LH induction ovulations.
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| 36. |
- Sporrong, B, et al.
(author)
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Histochemistry and ultrastructure of adrenergic and acetylcholinesterase-containing nerves supplying follicles and endocrine cells in the guinea-pig ovary
- 1985
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In: Cell and Tissue Research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 240:3, s. 11-505
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Journal article (peer-reviewed)abstract
- The autonomic nerve supply of the guinea-pig ovary was investigated by a combination of light- and electron microscopy. At the light-microscopic level, adrenergic fibres were identified due to their formaldehyde-induced fluorescence. In addition, the ovary contained acetylcholinesterase-positive fibres. In all parts of the ovary, the adrenergic fibres were most numerous. At the ultrastructural level it was possible to identify the adrenergic nerve terminals with the aid of the false adrenergic transmitter, 5-hydroxy-dopamine. Thus, large numbers of adrenergic terminals, characterized by their content of 50-60 nm, electron-dense synaptic vesicles, were seen within the interstitial gland, where they formed close contacts with the endocrine cells (membrane-to-membrane distance, 20-100 nm). The follicular theca externa was also richly supplied by adrenergic nerves. At this location, close contacts (50-100 nm) were identified between the nerve terminals and the smooth muscle-like cells. Very few adrenergic nerve fibres were present in the theca interna of follicles or in the corpus luteum. Non-adrenergic nerve terminals, characterized by electron-lucent synaptic vesicles of 50-60 nm diameter, were observed together with the adrenergic fibres. They were always present in much lower numbers than the latter. No "p-type" nerves were identified by electron microscopy.
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| 37. |
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