| 1. |
- Carlsson, Marcus, et al.
(författare)
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Total heart volume variation throughout the cardiac cycle in man.
- 2004
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Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 287:1, s. 243-250
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Tidskriftsartikel (refereegranskat)abstract
- Variations in total heart volume (atria plus ventricles) during a cardiac cycle affect efficiency of cardiac pumping. The goals of this study were to confirm the presence, extent, and contributors of total heart volume variation during the cardiac cycle in healthy volunteers with the use of MRI. Eight healthy volunteers were examined by MRI at rest. Changes in total cardiac volume throughout the cardiac cycle were calculated using the following methods: 1) planimetry derived from gradient-echo cine images and 2) flow-sensitive sequences to quantify flow in all vessels leading to and from the heart. The maximum total heart volume diminished during systole by 8.2 +/- 0.8% (SEM, range 4.8-10.6%) measured by method 1 and 8.8 +/- 1.0% (SEM, range 5.6-11.8%) by method 2 with good agreement between the methods [difference according to Bland-Altman analysis -0.6% +/- 1.0% (SD), intraclass correlation coefficient = 0.999]. This decrease in volume is predominantly explained by variation at the midcardiac level at the widest diameter of the heart with a left-sided predominance. In the short axis of the heart, the change of slice volume was proportional to the end-diastolic slice volume. The present study has confirmed the presence of total heart volume variation that predominantly occurs in the region of atrioventricular plane movement and on the left side. The total heart volume variation may relate to the efficiency of energy use by the heart to minimize displacement of surrounding tissue while accounting for the energy required to draw blood into the atria during ventricular systole.
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| 2. |
- Ebbesson, Lars, et al.
(författare)
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Neural circuits and their structural and chemical reorganization in the light-brain-pituitary axis during parr-smolt transformation in salmon
- 2003
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Ingår i: Aquaculture. - 0044-8486. ; 222:1-4, s. 59-70
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Tidskriftsartikel (refereegranskat)abstract
- Salmonid parr-smolt transformation (smoltification) is a transitional stage between freshwater and seawater life when the salmon imprint on their natal stream, change from a territorial feeding behavior to downstream migration, increase their hypoosmoregulatory competence, and change body shape and coloration. Photoperiod is recognized as the most potent initiator and regulator of the smoltification processes. Environmental light signals giving information about photoperiod are conveyed through a light-brain-pituitary axis that encompasses the neural pathways between photoreceptor organs, the brain and the pituitary, and the diurnal rhythm in melatonin secretion by the photosensory pineal organ. In addition, changes in photoperiod may elicit changes in this axis. Employing retinal neural tract tracing and growth associated protein-43 (GAP-43) immunocytochemistry, we provide here new evidence of a structural reorganization in the light-brain-pituitary axis during smoltification. Retinal tract tracing revealed that projections in smolts expand into new territories of the ipsilateral nucleus preopticus parvocellularis pars anterior (PPa) and additional fibers invade deeper into the contralateral PPa and the nucleus preopticus magnocellularis (PM). At this time, GAP-43-immunoreactive cells appear transiently in specific cell groups throughout the brain, but mainly in the olfactory bulb, telencephalon, and hypothalamus. These structural changes in the light-brain-pituitary axis and hypophysiotropic systems are followed by sequential surges of brain neurotransmitters and receptors, and occur prior to the major surges of circulating thyroid hormone and growth hormone levels that are central to smoltification-related processes. Our data point to a specific period of structural reorganization in certain brain circuits, and we hypothesize that these are involved in triggering the subsequent behavioral, endocrine, and physiological changes associated with smoltification. (C) 2003 Published by Elsevier Science B.V.
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| 3. |
- Forsell, Johan, et al.
(författare)
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Molecular identification and developmental expression of UV and green opsin mRNAs in the pineal organ of the Atlantic halibut.
- 2002
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Ingår i: Developmental Brain Research. - 0165-3806. ; 136:1, s. 51-62
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Tidskriftsartikel (refereegranskat)abstract
- The pineal organ is the only differentiated photoreceptor organ present in embryos and early larvae of the Atlantic halibut (Hippoglossus hippoglossus). We investigated the molecular identity of opsins in the pineal organ, and their expression during different life stages. Using RT-PCR we identified two 681-bp gene sequences, named HPO1 and HPO4, in cDNA from adult pineal and whole embryos. The predicted amino acid sequences showed highest identity to the transmembrane regions of teleostean RH2 green cone opsins (HPO1, 72-91%) and SWS-1 UV cone opsins (HPO4, 71-83%). In situ hybridization revealed expression of HPO1 and HPO4 mRNA transcripts in photoreceptors in the pineal organ of embryos, larvae and adults. HPO1 and HPO4 mRNA transcripts were also expressed in the larval retina. Our study provides molecular evidence for short and middle wavelength light sensitive photoreceptors in the pineal organ of Atlantic halibut throughout life, and suggests that pineal photoreception may play an important role during embryonic and larval life stages, especially at the time when the retina does not possesses corresponding photoreceptor capacity.
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| 4. |
- Gärdenfors, Peter, et al.
(författare)
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Visualizing the meanings of words
- 2004
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Ingår i: Language and visualisation (Lund University cognitive studies ; 119). - 9197474193
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Bokkapitel (refereegranskat)abstract
- Abstract is not available.
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| 5. |
- Holmqvist, Catarina, et al.
(författare)
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Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: correlation to morphological imaging of collateral vessels.
- 2002
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 15:1, s. 39-46
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow. MATERIALS AND METHODS: Thirteen children with coarctation were examined with T1-weighted spin-echo (T1-W SE) imaging and 3D contrast-enhanced magnetic resonance angiography (MRA). MR velocity mapping was performed at four levels in the descending aorta. RESULTS: The flow immediately above and below the coarctation did not differ significantly. Measuring within the coarctation resulted in flow overestimation. The increase of flow from proximal to distal aorta was 12 +/- 21% in patients with no or uncertain collaterals and 69 +/- 55% in patients with pronounced collaterals. Spin-echo images and MRA were comparable in visualizing collateral vessels. The visual estimation of collaterals correlated reasonably well with flow quantification MR velocity mapping. CONCLUSION: Collateral flow assessment with MR velocity mapping is an accurate technique for evaluating the hemodynamic importance of a coarctation and is recommended if abundant collaterals are not visualized with spin echo or MRA.
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| 6. |
- Holmqvist, Catarina, et al.
(författare)
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Pre-operative evaluation with MR in tetralogy of fallot and pulmonary atresia with ventricular septal defect
- 2001
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 42:1, s. 63-69
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To assess whether MR imaging could replace angiography in preoperative evaluation of patients with tetralogy of Fallot and pulmonary atresia with ventricular septal defect (VSD), especially since the surgical correction was done earlier than was previously the rule. MATERIAL AND METHODS: Fourteen patients with tetralogy of Fallot (n = 10) or pulmonary atresia with VSD (n = 4), mean age 7.5 +/- 4.4 months, were evaluated with angiocardiography and MR before definitive surgical correction. RESULTS: There was good diagnostic agreement between the two modalities when evaluating right ventricular outflow obstruction; 86% for valvular and 93% for supravalvular stenosis, but the agreement was somewhat lower for the subvalvular obstruction (57%). Surgery findings, however, were in favour of MR in 5 patients concerning the subvalvular right ventricular outflow tract obstruction. MR images identified all stenoses in the right and left pulmonary arteries, but overlooked one stenosis in the main pulmonary artery. MR could evaluate patency in all palliative shunts. CONCLUSION: Even in this young age group, MR imaging offers a good alternative to angiocardiography for the pre-operative evaluation of the right ventricular outflow tract, the main pulmonary artery and the proximal right and left pulmonary arteries, before definitive surgical correction of tetralogy of Fallot and pulmonary atresia with VSD.
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