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- Zhu, Changlian, 1964, et al.
(author)
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Irradiation to the immature brain attenuates neurogenesis and exacerbates subsequent hypoxic-ischemic brain injury in the adult.
- 2009
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In: Journal of neurochemistry. - : Wiley. - 1471-4159 .- 0022-3042. ; 111:6, s. 1447-1456
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Journal article (peer-reviewed)abstract
- Abstract Cranial radiotherapy is common in pediatric oncology. Our purpose was to investigate if irradiation (IR) to the immature brain would increase the susceptibility to hypoxic- ischemic injury in adulthood. The left hemisphere of postnatal day 10 (P10) mice was irradiated with 8 Gy and subjected to hypoxia-ischemia (HI) on P60. Brain injury, neurogenesis and inflammation were evaluated 30 days after HI. IR alone caused significant hemispheric tissue loss, or lack of growth (2.8 +/- 0.42 mm(3), p<0.001). Tissue loss after HI (18.2 +/- 5.8 mm(3), p<0.05) was synergistically increased if preceded by IR (32.0 +/- 3.5 mm(3), p<0.05). Infarct volume (5.1 +/- 1.6 mm(3)) nearly doubled if HI was preceded by IR (9.8 +/- 1.2 mm(3), p<0.05). Pathological scoring revealed that IR aggravated hippocampal, cortical and striatal, but not thalamic, injury. Hippocampal neurogenesis decreased >50% after IR but was unchanged by HI alone. The number of newly formed microglia was three times higher after IR+HI than after HI alone. In summary, IR to the immature brain produced long-lasting changes, including decreased hippocampal neurogenesis, subsequently rendering the adult brain more susceptible to HI, resulting in larger infarcts, increased hemispheric tissue loss and more inflammation than in non-irradiated brains.
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| 2. |
- Zhu, Changlian, 1964, et al.
(author)
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Isoflurane anesthesia induced persistent, progressive memory impairment, caused a loss of neural stem cells, and reduced neurogenesis in young, but not adult, rodents.
- 2010
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In: Journal of cerebral blood flow and metabolism. - : SAGE Publications. - 1559-7016 .- 0271-678X. ; 30, s. 1017-1030
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Journal article (peer-reviewed)abstract
- Isoflurane and related anesthetics are widely used to anesthetize children, ranging from premature babies to adolescents. Concerns have been raised about the safety of these anesthetics in pediatric patients, particularly regarding possible negative effects on cognition. The purpose of this study was to investigate the effects of repeated isoflurane exposure of juvenile and mature animals on cognition and neurogenesis. Postnatal day 14 (P14) rats and mice, as well as adult (P60) rats, were anesthetized with isoflurane for 35 mins daily for four successive days. Object recognition, place learning and reversal learning as well as cell death and cytogenesis were evaluated. Object recognition and reversal learning were significantly impaired in isoflurane-treated young rats and mice, whereas adult animals were unaffected, and these deficits became more pronounced as the animals grew older. The memory deficit was paralleled by a decrease in the hippocampal stem cell pool and persistently reduced neurogenesis, subsequently causing a reduction in the number of dentate gyrus granule cell neurons in isoflurane-treated rats. There were no signs of increased cell death of progenitors or neurons in the hippocampus. These findings show a previously unknown mechanism of neurotoxicity, causing cognitive deficits in a clearly age-dependent manner.Journal of Cerebral Blood Flow & Metabolism advance online publication, 13 January 2010; doi:10.1038/jcbfm.2009.274.
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| 3. |
- Zhu, Changlian, 1964, et al.
(author)
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Repeated exposure of the developing rat brain to magnetic resonance imaging did not affect neurogenesis, cell death or memory function.
- 2011
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In: Biochemical and biophysical research communications. - : Elsevier BV. - 1090-2104 .- 0006-291X. ; 404:1, s. 291-6
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Journal article (peer-reviewed)abstract
- The effect of magnetic fields on the brain is a matter of debate. The objective of this study was to investigate whether repeated exposure to strong magnetic fields, such as during magnetic resonance imaging (MRI), could elicit changes in the developing rat brain. Embryonic day 15 (E15) and postnatal day 14 (P14) rats were exposed to MRI using a 7.05 T MR system. The animals were anesthetized and exposed for 35 min per day for 4 successive days. Control animals were anesthetized but no MRI was performed. Body temperature was maintained at 37°C. BrdU was injected after each session (50 mg/kg). One month later, cell proliferation, neurogenesis and astrogenesis in the dentate gyrus were evaluated, revealing no effects of MRI, neither in the E15, nor in the P14 group. DNA damage in the dentate gyrus in the P14 group was evaluated on P18, 1 day after the last session, using TUNEL staining. There was no difference in the number of TUNEL-positive cells after MRI compared with controls, neither in mature neurons, nor in newborn progenitors (BrdU/TUNEL double-labeled cells). Novel object recognition was performed to assess memory function 1 month after MRI. There was no difference in the recognition index observed after MRI compared with the control rats, neither for the E15, nor for the P14 group. In conclusion, repeated exposure to MRI did not appear to affect neurogenesis, cell death or memory function in rats, neither in late gestation (E15-E18) nor in young postnatal (P14-P17) rats.
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