| 1. |
- Boström, Martina, et al.
(författare)
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Irradiation to the young mouse brain caused long-term, progressive depletion of neurogenesis but did not disrupt the neurovascular niche
- 2013
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 33:6, s. 935-943
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the effects of ionizing radiation on microvessel structure and complexity in the hippocampus. We also assessed neurogenesis and the neurovascular niche. Postnatal day 14 male C57BL/6 mice received a single dose of 8Gy to the whole brain and were killed 6 hours, 1 week, 7 weeks, or 1 year later. Irradiation decreased the total number of microvessels and branching points from 1 week onwards and decreased the total microvessel area 1 and 7 weeks after irradiation. After an initial increase in vascular parameter densities, concomitant with reduced growth of the hippocampus, the densities normalized with time, presumably adapting to the needs of the surrounding nonvascular tissue. Irradiation decreased the number of neural stem and progenitor cells in the hippocampus. The relative loss increased with time, resulting in almost completely ablated neurogenesis (DCX(+) cells) 1 year after irradiation (77% decreased 1 week, 86% decreased 7 weeks, and 98% decreased 1 year after irradiation compared with controls). After irradiation, the distance between undifferentiated stem cells and microvessels was unaffected, and very few dying endothelial cells were detected. Taken together, these results indicate that the vasculature adjusts to the surrounding neural and glial tissue after irradiation, not vice-versa.Journal of Cerebral Blood Flow & Metabolism advance online publication, 13 March 2013; doi:10.1038/jcbfm.2013.34.
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| 2. |
- Darsalia, Vladimer, et al.
(författare)
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Cell number and timing of transplantation determine survival of human neural stem cell grafts in stroke-damaged rat brain.
- 2011
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; Jul 1, s. 235-242
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Tidskriftsartikel (refereegranskat)abstract
- Neural stem cells (NSCs) derived from human fetal striatum and transplanted as neurospheres survive in stroke-damaged striatum, migrate from the implantation site, and differentiate into mature neurons. Here, we investigated how various steps of neurogenesis are affected by intrastriatal transplantation of human NSCs at different time points after stroke and with different numbers of cells in each implant. Rats were subjected to middle cerebral artery occlusion and then received intrastriatal transplants of NSCs. Transplantation shortly after stroke (48 hours) resulted in better cell survival than did transplantation 6 weeks after stroke, but the delayed transplantation did not influence the magnitude of migration, neuronal differentiation, and cell proliferation in the grafts. Transplanting greater numbers of grafted NSCs did not result in a greater number of surviving cells or increased neuronal differentiation. A substantial number of activated microglia was observed at 48 hours after the insult in the injured striatum, but reached maximum levels 1 to 6 weeks after stroke. Our findings show that the best survival of grafted human NSCs in stroke-damaged brain requires optimum numbers of cells to be transplanted in the early poststroke phase, before the inflammatory response is established. These findings, therefore, have direct clinical implications.Journal of Cerebral Blood Flow & Metabolism advance online publication, 9 June 2010; doi:10.1038/jcbfm.2010.81.
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| 3. |
- Dechent, Peter, et al.
(författare)
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Basal cerebral blood volume during the poststimulation undershoot in BOLD MRI of the human brain
- 2011
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016 .- 0271-678X. ; 31:1, s. 82-89
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Tidskriftsartikel (refereegranskat)abstract
- One of the characteristics of the blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) response to functional challenges of the brain is the poststimulation undershoot, which has been suggested to originate from a delayed recovery of either cerebral blood volume (CBV) or cerebral metabolic rate of oxygen to baseline. Using bolus-tracking MRI in humans, we recently showed that relative CBV rapidly normalizes after the end of stimulation. As this observation contradicts at least part of the blood-pool contrast agent studies performed in animals, we reinvestigated the CBV contribution by dynamic T1-weighted three-dimensional MRI (8 seconds temporal resolution) and Vasovist at 3 T (12 subjects). Initially, we determined the time constants of individual BOLD responses. After injection of Vasovist, CBV-related T1-weighted signal changes revealed a signal increase during visual stimulation (1.7%±0.4%), but no change relative to baseline in the poststimulation phase (0.2%±0.3%). This finding renders the specific nature of the contrast agent unlikely to be responsible for the discrepancy between human and animal studies. With the assumption of normalized cerebral blood flow after stimulus cessation, a normalized CBV lends support to the idea that the BOLD MRI undershoot reflects a prolonged elevation of oxidative metabolism.
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| 4. |
- Edvinsson, Lars, et al.
(författare)
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Vascular plasticity in cerebrovascular disorders.
- 2011
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 31, s. 1554-1571
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral ischemia remains a major cause of morbidity and mortality with little advancement in subacute treatment options. This review aims to cover and discuss novel insight obtained during the last decade into plastic changes in the vasoconstrictor receptor profiles of cerebral arteries and microvessels that takes place after different types of stroke. Receptors like the endothelin type B, angiotensin type 1, and 5-hydroxytryptamine type 1B/1D receptors are upregulated in the smooth muscle layer of cerebral arteries after different types of ischemic stroke as well as after subarachnoid hemorrhage, yielding rather dramatic changes in the contractility of the vessels. Some of the signal transduction processes mediating this receptor upregulation have been elucidated. In particular the extracellular regulated kinase 1/2 pathway, which is activated early in the process, has proven to be a promising therapeutic target for prevention of vasoconstrictor receptor upregulation after stroke. Together, those findings provide new perspectives on the pathophysiology of ischemic stroke and point toward a novel way of reducing vasoconstriction, neuronal cell death, and thus neurologic deficits after stroke.Journal of Cerebral Blood Flow & Metabolism advance online publication, 11 May 2011; doi:10.1038/jcbfm.2011.70.
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| 5. |
- Fernandez-Klett, F, et al.
(författare)
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Early loss of pericytes and perivascular stromal cell-induced scar formation after stroke
- 2013
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 33:3, s. 428-439
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Tidskriftsartikel (refereegranskat)abstract
- Despite its limited regenerative capacity, the central nervous system (CNS) shares more repair mechanisms with peripheral tissues than previously recognized. Scar formation is a ubiquitous healing mechanism aimed at patching tissue defects via the generation of fibrous extracellular matrix (ECM). This process, orchestrated by stromal cells, can unfavorably affect the capacity of tissues to restore function. Vascular mural cells have been found to contribute to scarring after spinal cord injury. In the case of stroke, little is known about the responses of pericytes (PCs) and stromal cells. Here, we show that capillary PCs are rapidly lost after cerebral ischemia in both experimental and human stroke. Coincident with this loss is a massive proliferation of resident platelet-derived growth factor receptor beta (PDGFRβ)+ and CD105+ stromal cells, which originate from the neurovascular unit and deposit ECM in the ischemic mouse brain. The presence of PDGFRβ+ stromal cells demarcates a fibrotic, contracted, and macrophage-laden lesion core from the rim of hypertrophic astroglia in both experimental and human stroke. We suggest that a previously unrecognized population of CNS-resident stromal cells drives a dynamic process of scarring after cerebral ischemia, which appears distinct from the glial scar and represents a novel target for regenerative stroke therapies.
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| 6. |
- Finnema, SJ, et al.
(författare)
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Confirmation of fenfluramine effect on 5-HT(1B) receptor binding of [(11)C]AZ10419369 using an equilibrium approach
- 2012
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 32:4, s. 685-695
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Tidskriftsartikel (refereegranskat)abstract
- Assessment of serotonin release in the living brain with positron emission tomography (PET) may have been hampered by the lack of suitable radioligands. We previously reported that fenfluramine caused a dose-dependent reduction in specific binding in monkeys using a classical displacement paradigm with bolus administration of [11C]AZ10419369. The aim of this study was to confirm our previous findings using an equilibrium approach in monkey. A total of 24 PET measurements were conducted using a bolus infusion protocol of [11C]AZ10419369 in three cynomolgus monkeys. Initial PET measurements were performed to assess suitable Kbol values. The fenfluramine effect on [11C]AZ10419369 binding was evaluated in a displacement and pretreatment paradigm. The effect of fenfluramine on [11C]AZ10419369 binding potential ( BPND) was dose-dependent in the displacement paradigm and confirmed in the pretreatment paradigm. After pretreatment administration of fenfluramine (5.0 mg/kg), the mean BPND of the occipital cortex decreased by 39%, from 1.38 ± 0.04 to 0.84 ± 0.09. This study confirms that the new 5-HT1B receptor radioligand [11C]AZ10419369 is sensitive to fenfluramine-induced changes in endogenous serotonin levels in vivo. The more advanced methodology is suitable for exploring the sensitivity limit to serotonin release as measured using [11C]AZ10419369 and PET.
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| 7. |
- Fridén, Markus, et al.
(författare)
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Improved measurement of drug exposure in the brain using drug-specific correction for residual blood
- 2010
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 0271-678X .- 1559-7016. ; 30:1, s. 150-161
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Tidskriftsartikel (refereegranskat)abstract
- A major challenge associated with the determination of the unbound brain-to-plasma concentration ratio of a drug (K(p,uu,brain)), is the error associated with correction for the drug in various vascular spaces of the brain, i.e., in residual blood. The apparent brain vascular spaces of plasma water (V(water), 10.3 microL/g brain), plasma proteins (V(protein), 7.99 microL/g brain), and the volume of erythrocytes (V(er), 2.13 microL/g brain) were determined and incorporated into a novel, drug-specific correction model that took the drug-unbound fraction in the plasma (f(u,p)) into account. The correction model was successfully applied for the determination of K(p,uu,brain) for indomethacin, loperamide, and moxalactam, which had potential problems associated with correction. The influence on correction of the drug associated with erythrocytes was shown to be minimal. Therefore, it is proposed that correction for residual blood can be performed using an effective plasma space in the brain (V(eff)), which is calculated from the measured f(u,p) of the particular drug as well as from the estimates of V(water) and V(protein), which are provided in this study. Furthermore, the results highlight the value of determining K(p,uu,brain) with statistical precision to enable appropriate interpretation of brain exposure for drugs that appear to be restricted to the brain vascular spaces.
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| 8. |
- Haast, Roy A.M., et al.
(författare)
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Sex differences in stroke
- 2012
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 0271-678X .- 1559-7016. ; 32:12, s. 2100-2107
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Tidskriftsartikel (refereegranskat)abstract
- Sex differences in stroke are observed across epidemiologic studies, pathophysiology, treatments, and outcomes. These sex differences have profound implications for effective prevention and treatment and are the focus of this review. Epidemiologic studies reveal a clear age-by-sex interaction in stroke prevalence, incidence, and mortality. While premenopausal women experience fewer strokes than men of comparable age, stroke rates increase among postmenopausal women compared with age-matched men. This postmenopausal phenomenon, in combination with living longer, are reasons for women being older at stroke onset and suffering more severe strokes. Thus, a primary focus of stroke prevention has been based on sex steroid hormone-dependent mechanisms. Sex hormones affect different (patho)physiologic functions of the cerebral circulation. Clarifying the impact of sex hormones on cerebral vasculature using suitable animal models is essential to elucidate male–female differences in stroke pathophysiology and development of sex-specific treatments. Much remains to be learned about sex differences in stroke as anatomic and genetic factors may also contribute, revealing its multifactorial nature. In addition, the aftermath of stroke appears to be more adverse in women than in men, again based on older age at stroke onset, longer prehospital delays, and potentially, differences in treatment.
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| 9. |
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| 10. |
- Inacio, Ana, et al.
(författare)
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Macrophage migration inhibitory factor promotes cell death and aggravates neurologic deficits after experimental stroke.
- 2011
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; Dec, s. 1093-1106
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Tidskriftsartikel (refereegranskat)abstract
- Multiple mechanisms contribute to tissue demise and functional recovery after stroke. We studied the involvement of macrophage migration inhibitory factor (MIF) in cell death and development of neurologic deficits after experimental stroke. Macrophage migration inhibitory factor is upregulated in the brain after cerebral ischemia, and disruption of the Mif gene in mice leads to a smaller infarct volume and better sensory-motor function after transient middle cerebral artery occlusion (tMCAo). In mice subjected to tMCAo, we found that MIF accumulates in neurons of the peri-infarct region, particularly in cortical parvalbumin-positive interneurons. Likewise, in cultured cortical neurons exposed to oxygen and glucose deprivation, MIF levels increase, and inhibition of MIF by (S,R)-3-(4-hydroxyphenyl)-4,5-dihydro-5-isoxazole acetic acid methyl ester (ISO-1) protects against cell death. Deletion of MIF in Mif(-/-) mice does not affect interleukin-1β protein levels in the brain and serum after tMCAo. Furthermore, disruption of the Mif gene in mice does not affect CD68, but it is associated with higher galectin-3 immunoreactivity in the brain after tMCAo, suggesting that MIF affects the molecular/cellular composition of the macrophages/microglia response after experimental stroke. We conclude that MIF promotes neuronal death and aggravates neurologic deficits after experimental stroke, which implicates MIF in the pathogenesis of neuronal injury after stroke.Journal of Cerebral Blood Flow & Metabolism advance online publication, 10 November 2010; doi:10.1038/jcbfm.2010.194.
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