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81.
Magnetic resonance analysis of the effects of acute ammonia intoxication on rat brain. Role of NMDA receptors 总被引:2,自引:0,他引:2
Cauli O López-Larrubia P Rodrigues TB Cerdán S Felipo V 《Journal of neurochemistry》2007,103(4):1334-1343
Acute ammonia intoxication leads to rapid death, which is prevented by blocking N -methyl- d -aspartate (NMDA) receptors. The subsequent mechanisms leading to death remain unclear. Brain edema seems an important step. The aim of this work was to study the effects of acute ammonia intoxication on different cerebral parameters in vivo using magnetic resonance and to assess which effects are mediated by NMDA receptors activation. To assess edema induction, we injected rats with ammonium acetate and measured apparent diffusion coefficient (ADC) in 16 brain areas. We also analyzed the effects on T1, T2, and T2* maps and whether these effects are prevented by blocking NMDA receptors. The effects of acute ammonia intoxication are different in different brain areas. T1 relaxation time is reduced in eight areas. T2 relaxation time is reduced only in ventral thalamus and globus pallidus. ADC values increased in hippocampus, caudate-putamen, substantia nigra and cerebellar cortex, reflecting vasogenic edema. ADC decreased in hypothalamus, reflecting cytotoxic edema. Myo-inositol increased in cerebellum and substantia nigra, reflecting vasogenic edema. N -acetyl-aspartate decreased in cerebellum, reflecting neuronal damage. Changes in N -acetyl-aspartate, T1 and T2 are prevented by blocking NMDA receptors with MK-801 while changes in ADC or myo-inositol (induction of edema) are not. 相似文献
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St Martin JL Klucken J Outeiro TF Nguyen P Keller-McGandy C Cantuti-Castelvetri I Grammatopoulos TN Standaert DG Hyman BT McLean PJ 《Journal of neurochemistry》2007,100(6):1449-1457
Several transgenic mouse lines with altered alpha-synuclein expression have been developed that show a variety of Parkinson's disease-like symptoms without specific loss of dopaminergic neurons. Targeted over-expression of human alpha-synuclein using viral-vector mediated gene delivery into the substantia nigra of rats and non-human primates leads to dopaminergic cell loss and the formation of alpha-synuclein aggregates reminiscent of Lewy bodies. In the context of these recent findings, we used adeno-associated virus (AAV) to over-express wild type human alpha-synuclein in the substantia nigra of mice. We hypothesized that this over-expression would recapitulate pathological hallmarks of Parkinson's disease, creating a mouse model to further characterize the disease pathogenesis. Recombinant AAV expressing alpha-synuclein was stereotaxically injected into the substantia nigra of mice, leading to a 25% reduction of dopaminergic neurons after 24 weeks of transduction. Furthermore, examination of mRNA levels of stress-related proteins using laser capture microdissection and quantitative PCR revealed a positive correlation of Hsp27 expression with the extent of viral transduction at 4 weeks and a positive correlation of Hsp40, Hsp70 and caspase 9 with the extent of viral transduction at 24 weeks. Taken together, our findings suggest that targeted over-expression of alpha-synuclein can induce pathology at the gross anatomical and molecular level in the substantia nigra, providing a mouse model in which upstream changes in Parkinson's disease pathogenesis can be further elucidated. 相似文献
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Physiological adaptations to head-out aquatic exercises with different levels of body immersion 总被引:1,自引:0,他引:1
Barbosa TM Garrido MF Bragada J 《Journal of strength and conditioning research / National Strength & Conditioning Association》2007,21(4):1255-1259
The purpose of this study was to compare the physiological adaptations to basic head-out aquatic exercises with different levels of body immersion. Sixteen young and clinically healthy subjects (9 women and 7 men) volunteered to participate in this study. Each subject performed 3 repetitions (on land, immersed to the hip, and immersed to the breast) of the aquatic exercise "rocking horse" for 6 minutes. The rating of perceived effort (RPE), the maximal heart rate achieved during the exercitation (HRmax), the percentage of the maximal theoretical heart rate estimated (%HRmax), the peak of oxygen uptake during the exercise (V(.-)O2peak), and the energy expenditure (EE) were evaluated. The RPE was significantly higher when exercising immersed to the hip than on land (p < 0.01) and immersed to the breast (p = 0.03). The HRmax and %HRmax were significantly lower when exercising with immersion to the breast than on land (p < 0.01) and with immersion to the hip (p < 0.01). The V(.-)O2peak was significantly different between all conditions. The lower mean value was verified when exercising immersed to the breast, followed by immersion to the hip and on land. The EE was significantly higher when performing aquatic exercises on land than when immersed to the hip (p = 0.02) and the breast (p < 0.01). So, physiological responses when exercising immersed to the hip are higher than when immersed to the breast. The physiological responses when exercising on land are higher than when exercising with immersion to the hip and to the breast. 相似文献
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Pereira P Vinadé E Rodrigues L De David e Silva TL Ardenghi P da Silva Brum LF Gonçalves CA Izquierdo I 《Neurochemical research》2007,32(7):1150-1155
The participation of protein serine/threonine kinases in memory formation and retrieval is well established. In contrast,
relatively little is known on the role of protein tyrosine kinases (PTKs). Previous work showed that intra-hippocampal infusion
of the Src-PTK inhibitor radicicol inhibits memory acquisition, consolidation, and retrieval of one-trial step-down inhibitory avoidance
task. In this study, we investigated the possible interaction between levels of Src-PTK activity in hippocampus and memory acquisition, formation, and retrieval of this task. Radicicol (0.5 μg/ml) was infused
into the CA1 region of the hippocampus of rats trained in a one-trial step-down inhibitory avoidance task. Radicicol infused
15 min before training decreased Src-PTK activity, as measured 0, 1.5, and 24 h after training, and impaired memory acquisition of the task. When given immediately
after training, there was a decrease in Src-PTK activity 1.5 h, but not 0 or 24 h after training. This treatment depressed memory consolidation. Radicicol infused into
CA1 10 min prior to retrieval testing inhibited hippocampal Src-PTK activity, as measured immediately after the test session. The results suggest that Src-PTKs participate in memory acquisition, consolidation, and retrieval processes, but the timing of the role of the enzyme
is different in each case. 相似文献
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Pereira L Gonçalves J Franco-Duarte R Silva J Rocha T Arnold C Richards M Macaulay V 《Molecular biology and evolution》2007,24(3):868-874
The first complete mitochondrial DNA (mtDNA) sequences (approximately 16,569 bp) in 20 patients with asthenozoospermia and a comparison with 23 new complete mtDNA sequences in teratoasthenozoospermic individuals, confirmed no sharing of specific polymorphisms or specific mitochondrial lineages between these individuals. This is strong evidence against the accepted claim of a major role played by mtDNA in male fertility, once supported by haplogroup association studies based on the screening of hypervariable region I. The hypothesis of maternally driven selection acting in male reproductive success must thus be treated with caution. 相似文献
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Jesus Ronald Ferreira Santos Ana Nunes Nandyara Bianca dos Santos Jeannie Nascimento Melo Francisco Tiago Vasconcelos 《Systematic parasitology》2022,99(6):761-769
Systematic Parasitology - Nematodes collected from the stomach and large intestine of Rhinoclemmys punctularia (Daudin) from the eastern Amazon, Brazil, are assigned to a new genus, Vogtnema n.... 相似文献
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