Noninvasive detection of brainstem and spinal cord axonal degeneration in an amyotrophic lateral sclerosis mouse model

Degeneration of motor neurons and their associated axons is a hallmark of amyotrophic lateral sclerosis, but reliable noninvasive lesion detection is lacking. In vivo diffusion tensor imaging was performed to evaluate neurodegeneration in the brainstem and cervical spinal cord of wild-type and G93A-SOD1 transgenic mice, an animal model of amyotrophic lateral sclerosis. A statistically significant reduction in the apparent diffusion coefficient was observed in the motor nuclei VII and XII of G93A-SOD1 transgenic mice relative to wild-type mice. No significant difference in diffusion anisotropy was observed in dorsal white or gray matter in cervical and lumbar segments of the spinal cord. In contrast, statistically significant decreases in axial diffusivity (diffusivity parallel to the axis of the spinal cord) and apparent diffusion coefficient were found in the ventrolateral white matter of G93A-SOD1 mice in both the cervical and lumbar spinal cord. The reduction in axial diffusivity, suggestive of axonal injury, in the white matter of the spinal cord of G93A-SOD1 mice was verified by immunostaining with nonphosphorylated neurofilament. The present study demonstrates that in vivo diffusion tensor imaging-derived axial diffusivity may be used to accurately evaluate axonal degeneration in an animal model of amyotrophic lateral sclerosis.     

P2X7 activation enhances skeletal muscle metabolism and regeneration in SOD1G93A mouse model of amyotrophic lateral sclerosis

Muscle weakness plays an important role in neuromuscular disorders comprising amyotrophic lateral sclerosis (ALS). However, it is not established whether muscle denervation originates from the motor neurons, the muscles or more likely both. Previous studies have shown that the expression of the SOD1G93A mutation in skeletal muscles causes denervation of the neuromuscular junctions, inability to regenerate and consequent atrophy, all clear symptoms of ALS. In this work, we used SOD1G93A mice, a model that best mimics some pathological features of both familial and sporadic ALS, and we investigated some biological effects induced by the activation of the P2X7 receptor in the skeletal muscles. The P2X7, belonging to the ionotropic family of purinergic receptors for extracellular ATP, is abundantly expressed in the healthy skeletal muscles, where it controls cell duplication, differentiation, regeneration or death. In particular, we evaluated whether an in vivo treatment in SOD1G93A mice with the P2X7 specific agonist 2′(3′)‐O‐(4‐Benzoylbenzoyl) adenosine5′‐triphosphate (BzATP) just before the onset of a pathological neuromuscular phenotype could exert beneficial effects in the skeletal muscles. Our findings indicate that stimulation of P2X7 improves the innervation and metabolism of myofibers, moreover elicits the proliferation/differentiation of satellite cells, thus preventing the denervation atrophy of skeletal muscles in SOD1G93A mice. Overall, this study suggests that a P2X7‐targeted and site‐specific modulation might be a strategy to interfere with the complex multifactorial and multisystem nature of ALS.     

MRI detects early hindlimb muscle atrophy in Gly93Ala superoxide dismutase-1 (G93A SOD1) transgenic mice, an animal model of familial amyotrophic lateral sclerosis

MRI has been used to measure hindlimb muscle volume in female and male transgenic mice overexpressing the Gly93Ala (G93A) mutant human superoxide dismutase 1 (SOD1), a widely used model of familial amyotrophic lateral sclerosis (FALS), over the first 4 months of life. Significant decreases in the hindlimb muscle volume of the female G93A SOD1 mice were evident from 11 weeks of age, before other overt pathology appeared. By 15 weeks volume had decreased by 37% compared with 7 weeks, from 0.84+/-0.04 cm(3) (mean+/-standard deviation, n = 6) to 0.54+/-0.07 cm(3), (p < 0.05), despite an increase in body weight of ca. 12% (from 16.2 +/- 1.4 to 18.1 +/- 0.7 g). Female wild-type volume increased by ca. 30% whilst the body weight increased by 15%. Muscle wasteage was less (0.82+/-0.1 to 0.65+/-0.02 cm(3), p < 0.05, n = 6) in male G93A SOD1 mice between 8 and 16 weeks of age, against a body weight increase trend from 20.7 +/- 0.4 to 21.6 +/- 0.5 g, (p > 0.05). Wild-type male muscle volume did not change significantly over this period, with an increase in body weight of 20%. Longitudinal MRI hindlimb muscle volume measurements may provide a straightforward, rapid, non-invasive and sensitive, way of monitoring outcome of experimental ALS treatments.     

RhoA和ROCK2在SOD1-G93A转基因小鼠脊髓中的表达

目的:通过研究Rho A和ROCK2在SOD1-G93A转基因小鼠脊髓内的表达变化以阐明Rho/ROCK信号通路在肌萎缩侧索硬化症(ALS)病程中的作用。方法:饲养SOD1-G93A转基因小鼠和同窝野生型小鼠至发病早期、中期和晚期,部分小鼠冰上剥离新鲜脊髓组织,利用RT-PCR方法检测Rho A和ROCK2 mRNA的表达,利用Western Blot方法检测Rho A和ROCK2蛋白的表达;部分小鼠行心脏灌注并剥离其脊髓组织制成冰冻切片,利用免疫组织化学染色方法检测Rho A和ROCK2蛋白的表达。结果:在SOD1-G93A鼠发病的早期、中期和晚期,转基因小鼠脊髓中Rho A和ROCK2的mRNA及蛋白表达均上调。免疫组织化学染色实验结果显示,野生型小鼠脊髓中Rho A和ROCK2弥散分布于胞质和突起中,阳性染色浅,SOD1-G93A转基因小鼠脊髓中Rho A和ROCK2阳性染色深,大量聚集在细胞膜及细胞质。结论:Rho A和ROCK2在SOD1-G93A转基因小鼠脊髓中异常高水平表达与ALS脊髓区病变密切相关,可能参与ALS疾病进程。     

Immunohistochemical study on choline acetyltransferase in the spinal cord of patients with amyotrophic lateral sclerosis

The authors developed a polyclonal antibody against a fusion protein containing 598 amino acids from a human choline acetyltransferase (ChAT) cDNA and 12 amino acids derived from an expression vector, and examined immunohistochemical reactivity for ChAT in large motor neurons (30 μn and more in somal minimal diameter) of the lumbar spinal cords of four patients with amyotrophic lateral sclerosis (ALS) and of four control cases. In controls, the number of large neurons included in the tissue with a total thickness of 100 μm ranged from 74 to 105 (average 87). About 60–90% (average 80%) of the neurons were positively stained in their perikarya with an anti-human ChAT antibody. In the cases of ALS, the number of large motor neurons was greatly reduced (25–60, average 38). About 4–13% (average 8%) were positively stained. These results indicate that not only large neurons are reduced in number, but also their positivity for ChAT is decreased in the anterior horn of ALS spinal cord.     

Nrf2/HO-1在肌萎缩侧索硬化症转基因小鼠脊髓中的表达变化

目的:检测不同疾病阶段肌萎缩侧索硬化症(ALS)转基因小鼠脊髓内Nrf2及HO-1表达变化,以探究抗氧化应激能力变化与ALS发病的关系。方法:应用免疫荧光双重标记和Western Blot技术检测Nrf2及其下游调节蛋白HO-1在ALS发病早期(95 d)、发病晚期(122 d)脊髓中的表达差异。结果:与同窝别野生型鼠相比较,免疫荧光双重标记结果显示:95 d、122 d ALS鼠脊髓腰段内Nrf2~+/GFAP~+星形胶质细胞增多;虽与同时间点同窝别野生型鼠比较,ALS转基因鼠脊髓中Nrf2蛋白表达略有升高,但差异无统计学意义。HO-1蛋白表达在ALS早期95 d趋势与Nrf2相同,前角神经元内表达较多;至122 d转基因鼠脊髓内HO-1~+表达多集中于星形胶质细胞内,且脊髓内HO-1蛋白总量较同窝别野生型鼠显著升高(P0.05)。结论:ALS运动神经元退变可能与星形胶质细胞激活后Nrf2及HO-1参与的氧化应激机制有关。     

肌萎缩侧索硬化小鼠内源性神经干细胞膜突触蛋白表达

背景：成纤维细胞生长因子2是神经系统主要的神经营养因子之一,目前已经被证明有促进内源性神经干细胞分化的作用。 目的：观察成纤维细胞生长因子2干预下,肌萎缩侧索硬化SOD1G93A G1H转基因小鼠运动功能的改变,内源性神经干细胞的增殖情况,突触蛋白的水平改变及内源性神经干细胞增殖数目与突触蛋白水平改变的相关性。 方法：取新出生SOD1G93A G1H转基因小鼠(肌萎缩侧索硬化模型小鼠)60只分为肌萎缩侧索硬化组及成纤维细胞生长因子2组各30只,取新出生野生B6SJL小鼠30只作为正常对照组,成纤维细胞生长因子2组腹腔注入成纤维细胞生长因子2;肌萎缩侧索硬化组和正常对照组腹腔注入安慰剂生理盐水。分别于出生后60,90,120 d采用Rotarod方法评估小鼠运动功能的改变,采用免疫组织化学方法标记内源性神经干细胞和突触蛋白并计数,用spearman方法评估内源性神经干细胞增殖数目与突触蛋白水平的相关性。 结果与结论：与肌萎缩侧索硬化组相比,成纤维细胞生长因子2组小鼠运动功能明显改善,内源性神经干细胞增殖和突触蛋白水平显著增高。小鼠内源性神经干细胞的增加与突触蛋白水平的增呈正相关。提示成纤维细胞生长因子2神经保护机制可能与其促进内源性神经干细胞增殖和提升突触蛋白水平相关。     

人骨髓间质干细胞治疗肌萎缩侧索硬化症模型小鼠的行为学和病理学研究

目的:研究静脉移植人骨髓间质干细胞对肌萎缩侧索硬化症(ALS)模型小鼠生存期和病理变化的影响。方法:体外培养扩增人骨髓间质干细胞(hMSCs),流式细胞仪鉴定hMSCs的性质及纯度,微量尾静脉血提取模型小鼠DNA,PCR扩增鉴定肌萎缩侧索硬化症模型小鼠(SOD1-G93A阳性小鼠)。将3×106个第5代hM-SCs尾静脉移植入预放疗8周的SOD1-G93A阳性小鼠,用Weyd4分法进行评定移植小鼠和未治疗小鼠的生存期、发病时间,尼氏染色计数脊髓前角运动神经元,组织DNA提取、PCR检测人特异性基因β-globin基因来验证hMSCs在受体小鼠中的植入。结果:生存分析显示尾静脉移植hMSCs的ALS模型小鼠生存期比未治疗小鼠延长18d,延缓发病14d;尼氏染色显示在16周、20周移植小鼠脊髓前角大运动神经元计数多于未治疗小鼠;终末期hMSCs移植小鼠中,在中枢神经系统可检测到人特异性该基因。结论:hMSCs可经过尾静脉移植在ALS小鼠中长期植入,延长生存期,减少脊髓前角运动神经元的丢失,有一定的治疗作用。     

Distribution and cellular localization of high mobility group box protein 1 (HMGB1) in the spinal cord of a transgenic mouse model of ALS

Although the aetiology of amyotrophic lateral sclerosis (ALS) is still elusive, increased attention has been put forward on events related to neuroinflammation and an active participation of glial cells in the ALS pathogenesis has been suggested. However, the specific role of many proinflammatory mediators that usually accompany the inflammatory changes is still largely unknown. High mobility group box protein 1 (HMGB1) is an ubiquitous nuclear protein that exerts numerous extranuclear and extracellular functions, including a proinflammatory activity, able to induce cytokines expression and activate inflammatory cells. To investigate whether this protein may play a role in the inflammatory events in ALS, we examined both expression and localization of HMGB1 in the lumbar spinal cord of SOD1G93A transgenic mice, a well established mouse model of familial ALS, at different stages of the disease. Intense HMGB1 reactivity was detected in ventral horn motor neurons of both non-transgenic and SOD1G93A mice and there was no difference in its expression between presymptomatic SOD1G93A mice and controls. With the progression of the disease, degenerating neurons showed a reduction of HMGB1 immunoreactivity which could reflect an extracellular release of this protein. By contrast, in the reactive glial cells HMGB1 was remarkably expressed in the nucleus, but not in the cytosol, likely contributing to the proliferation and/or hypertrophy of these cells. These results suggest that HMGB1 may have a different involvement in the motor neurons and glial cells in response to the neurotoxic environment in the spinal cord of SOD1G93A mice, and it may contribute to the progression of inflammatory and neurodegenerative processes.     

Notch1在肌萎缩侧索硬化症转基因鼠动物模型和细胞模型中的表达变化

目的:观察Notch1在肌萎缩侧索硬化症(ALS)转基因鼠动物模型和细胞模型中的表达情况。方法:应用免疫荧光、免疫印迹、RT-PCR,检测Notch1在95、108、122 d ALS转基因鼠脊髓中的表达变化;检测转染pEGFP-wt-SOD1和pEGFPG93A-SOD1的NSC34细胞模型中Notch1的表达变化。结果:Notch1可与β-tubulinⅢ共表达,与GFAP无明显共表达。较同窝野生型鼠,Notch1于蛋白水平和mRNA水平上的表达在95 d ALS转基因鼠脊髓中无明显变化,在108 d和122 d ALS转基因鼠脊髓中明显升高;与转染pEGFP-wt-SOD的NSC34细胞相比,转染pEGFP-G93A-SOD1的NSC34细胞中Notch1蛋白和mRNA表达增多。结论:Notch1在ALS转基因鼠动物模型和细胞模型中表达增多,提示Notch1信号通路可能与ALS相关。     

A meta-analysis of diffusion tensor imaging studies in amyotrophic lateral sclerosis

Studies involving diffusion tensor imaging (DTI) of amyotrophic lateral sclerosis (ALS) with whole-brain voxel-based analysis yielded variable findings. A systematic review was conducted on whole-brain voxel-based diffusion tensor imaging fractional anisotropy (FA) studies of ALS patients and healthy controls (HC) in PubMed, ISI Web of Science, Embase, and MEDLINE databases from 1990 to December 25, 2010. Coordinates were extracted from clusters with significant difference in FA between ALS patients and HC. Meta-analysis was performed using signed differential mapping. Eight studies were enrolled, comprising 143 ALS patients and 145 HC. The included studies reported FA reduction at 67 coordinates in ALS and no FA increased. Significant reductions were present in the bilateral frontal white matter/cingulate gyrus and the posterior limb of bilateral internal capsule. The findings remain largely unchanged in quartile and jackknife sensitivity analyses. Our finding suggests that ALS is a multisystem disease beyond motor dysfunction and provides evidence that FA reduction in the frontal white matter and cingulate gyrus may be a special biomarker of ALS.     

Diffusion tensor imaging detects axonal injury and demyelination in the spinal cord and cranial nerves of a murine model of globoid cell leukodystrophy

Globoid cell leukodystrophy is an inherited neurodegenerative disorder caused by a deficiency of the lysosomal enzyme galactosylceramidase. In both human patients and the authentic murine Twitcher model, pathological findings include demyelination as well as axonal damage in both the central and peripheral nervous system. Diffusion tensor imaging (DTI) has emerged as a powerful noninvasive technique that is sensitive to these white matter disease processes. Increases in radial diffusivity (λ?) and decreases in axial diffusivity (λ∥) correlate with histopathological evidence of demyelination and axonal damage, respectively. Compared to age‐matched, normal littermates, DTI of optic nerve and trigeminal nerve in end‐stage Twitcher mice displayed a statistically significant increase in λ? and decrease in λ∥, consistent with previously characterized demyelination and axonal damage in these regions. In the Twitcher spinal cord, a statistically significant decrease in λ∥ was identified in both the dorsal and ventrolateral white matter, relative to normal controls. These results were consistent with immunofluorescence evidence of axonal damage in these areas as detected by staining for nonphosphorylated neurofilaments (SMI32). Increase in λ? in Twitcher spinal cord white matter relative to normal controls reached statistical significance in the dorsal columns and approached statistical significance in the ventrolateral region. Correlative reduced levels of myelin basic protein were detected by immunofluorescent staining in both these white matter regions in the Twitcher spinal cord. Fractional anisotropy, a nonspecific but sensitive indicator of white matter disease, was significantly reduced in the optic nerve, trigeminal nerve, and throughout the spinal cord white matter of Twitcher mice, relative to normal controls. This first reported application of spinal cord DTI in the setting of GLD holds potential as a noninvasive, quantitative assay of therapeutic efficacy in future treatment studies. Copyright © 2009 John Wiley & Sons, Ltd.     

Region‐specific impairment of the cervical spinal cord (SC) in amyotrophic lateral sclerosis: A preliminary study using SC templates and quantitative MRI (diffusion tensor imaging/inhomogeneous magnetization transfer)

In this preliminary study, our objective was to investigate the potential of high‐resolution anatomical imaging, diffusion tensor imaging (DTI) and conventional/inhomogeneous magnetization transfer imaging [magnetization transfer (MT)/inhomogeneous magnetization transfer (ihMT)] at 3 T, analyzed with template‐extracted regions of interest, to measure the atrophy and structural changes of white (WM) and gray (GM) matter spinal cord (SC) occurring in patients with amyotrophic lateral sclerosis (ALS). Ten patients with ALS and 20 age‐matched healthy controls were recruited. SC GM and WM areas were automatically segmented using dedicated templates. Atrophy indices were evaluated from T ₂*‐weighted images at each vertebral level from cervical C1 to C6. DTI and ihMT metrics were quantified within the corticospinal tract (CST), posterior sensory tract (PST) and anterior GM (aGM) horns at the C2 and C5 levels. Clinical disabilities of patients with ALS were evaluated using the Revised ALS Functional Rating Scale, upper motor neuron (UMN) and Medical Research Council scorings, and correlated with MR metrics. Compared with healthy controls, GM and WM atrophy was observed in patients with ALS, especially at lower cervical levels, where a strong correlation was also observed between GM atrophy and the UMN score (R  = ?0.75, p  = 0.05 at C6). Interestingly, a significant decrease in ihMT ratio was found in all regions of interest (p  < 0.0008), fractional anisotropy (FA) and MT ratios decreased significantly in CST, especially at C5 (p  < 0.005), and λ_// (axial diffusivity) decreased significantly in CST (p  = 0.0004) and PST (p  = 0.003) at C2. Strong correlations between MRI metrics and clinical scores were also found (0.47 < |R | < 0.87, p  < 0.05). Altogether, these preliminary results suggest that high‐resolution anatomical imaging and ihMT imaging, in addition to DTI, are valuable for the characterization of SC tissue impairment in ALS. In this study, in addition to an important SC WM demyelination, we also observed, for the first time in ALS, impairments of cervical aGM.     

Axonal injury detected by in vivo diffusion tensor imaging correlates with neurological disability in a mouse model of multiple sclerosis

Recent studies have suggested that axonal damage, and not demyelination, is the primary cause of long-term neurological impairment in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). The axial and radial diffusivities derived from diffusion tensor imaging have shown promise as non-invasive surrogate markers of axonal damage and demyelination, respectively. In this study, in vivo diffusion tensor imaging of the spinal cords from mice with chronic EAE was performed to determine if axial diffusivity correlated with neurological disability in EAE assessed by the commonly used clinical scoring system. Axial diffusivity in the ventrolateral white matter showed a significant negative correlation with EAE clinical score and was significantly lower in mice with severe EAE than in mice with moderate EAE. Furthermore, the greater decreases in axial diffusivity were associated with greater amounts of axonal damage, as confirmed by quantitative staining for non-phosphorylated neurofilaments (SMI32). Radial diffusivity and relative anisotropy could not distinguish between the groups of mice with moderate EAE and those with severe EAE. The results further the notion that axial diffusivity is a non-invasive marker of axonal damage in white matter and could provide the necessary link between pathology and neurological disability.     

Short-scan-time multi-slice diffusion MRI of the mouse cervical spinal cord using echo planar imaging

Mouse spinal cord (SC) diffusion-weighted imaging (DWI) provides important information on tissue morphology and structural changes that may occur during pathologies such as multiple sclerosis or SC injury. The acquisition scheme of the commonly used DWI techniques is based on conventional spin-echo encoding, which is time-consuming. The purpose of this work was to investigate whether the use of echo planar imaging (EPI) would provide good-quality diffusion MR images of mouse SC, as well as accurate measurements of diffusion-derived metrics, and thus enable diffusion tensor imaging (DTI) and highly resolved DWI within reasonable scan times. A four-shot diffusion-weighted spin-echo EPI (SE-EPI) sequence was evaluated at 11.75 T on a group of healthy mice (n = 10). SE-EPI-derived apparent diffusion coefficients of gray and white matter were compared with those obtained using a conventional spin-echo sequence (c-SE) to validate the accuracy of the method. To take advantage of the reduction in acquisition time offered by the EPI sequence, multi-slice DTI acquisitions were performed covering the cervical segments (six slices, six diffusion-encoding directions, three b values) within 30 min (vs 2 h for c-SE). From these measurements, fractional anisotropy and mean diffusivities were calculated, and fiber tracking along the C1 to C6 cervical segments was performed. In addition, high-resolution images (74 x 94 microm(2)) were acquired within 5 min per direction. Clear delineation of gray and white matter and identical apparent diffusion coefficient values were obtained, with a threefold reduction in acquisition time compared with c-SE. While overcoming the difficulties associated with high spatially and temporally resolved DTI measurements, the present SE-EPI approach permitted identification of reliable quantitative parameters with a reproducibility compatible with the detection of pathologies. The SE-EPI method may be particularly valuable when multiple sets of images from the SC are needed, in cases of rapidly evolving conditions, to decrease the duration of anesthesia or to improve MR exploration by including additional MR measurements. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Lack of involvement of neuronal nitric oxide synthase in the pathogenesis of a transgenic mouse model of familial amyotrophic lateral sclerosis

A subset of familial cases of amyotrophic lateral sclerosis are linked to missense mutations in copper/zinc superoxide dismutase type 1. Patients with missense mutations in copper/zinc superoxide dismutase type 1 develop a paralytic disease indistinguishable from sporadic amyotrophic lateral sclerosis through an unknown toxic gain of function. Nitric oxide reacts with the superoxide anion to form the strong oxidant, peroxynitrite, which participates in neuronal injury in a variety of model systems. Peroxynitrite is an alternate substrate for copper/zinc superoxide dismutase type 1, causing catalytic nitration of tyrosine residues in other proteins. Mutations in copper/zinc superoxide dismutase type 1 may disrupt the active site of the enzyme and permit greater access of peroxynitrite to copper, leading to increased nitration by peroxynitrite of critical cellular targets. To investigate whether neuronal-derived nitric oxide plays a role in the pathogenesis of familial amyotrophic lateral sclerosis, we examined the effects of three different nitric oxide synthase inhibitors: a non-selective nitric oxide synthase inhibitor, nitro-L-arginine methyl ester; a relatively selective inhibitor of neuronal nitric oxide synthase, 7-nitroindazole; and a novel highly selective neuronal nitric oxide synthase inhibitor, AR-R 17,477, in transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 (Gly-->Ala at position 93; G93A) containing a high transgene copy number and a low transgene copy number. AR-R 17,477, but not nitro-L-arginine methyl ester or 7-nitroindazole, significantly prolonged survival in both the high and low transgene transgenic mice. To determine whether neuronal nitric oxide synthase is involved in the pathogenesis resulting from the familial amyotrophic lateral sclerosis copper/zinc superoxide dismutase type 1 mutation, we produced mice with the copper/zinc superoxide dismutase type 1 mutation which lack the neuronal nitric oxide synthase gene. The transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background do not live significantly longer than transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1. Western blot analysis indicates the presence of two neuronal nitric oxide synthase-like immunoreactive bands in spinal cord homogenates of the neuronal nitric oxide synthase null mice, and residual neuronal nitric oxide synthase catalytic activity ( > 7%) is detected in the spinal cord of the transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background. This amount of residual activity probably does not account for lack of protection afforded by the disrupted neuronal nitric oxide synthase gene in the familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 mice. Immunological nitric oxide synthase is not detected in the copper/zinc superoxide dismutase type 1 mutant mice at several different ages, thus excluding immunological nitric oxide synthase as a contributor to the pathogenesis of familial amyotrophic lateral sclerosis. Levels of neuronal nitric oxide synthase as well as Ca2+-dependent nitric oxide synthase catalytic activity in the copper/zinc superoxide dismutase type 1 mutant mice do not differ from wild type mice. Endothelial nitric oxide synthase levels may be decreased in the copper/zinc superoxide dismutase type 1 mutant mice. Together, these results do not support a significant role for neuronal-derived nitric oxide in the pathogenesis of familial amyotrophic lateral sclerosis transgenic mice.     

Neurogenin1在肌萎缩脊髓侧索硬化症转基因鼠脊髓中的表达变化

目的:研究neurogenin 1 (Ngn1)转录因子在成年肌萎缩脊髓侧索硬化症(ALS)转基因模型鼠脊髓内的表达变化,探讨其在ALS转基因鼠发病中的作用.方法:选取ALS转基因鼠和同窝野生型鼠各18只,分别于95、108 d和122 d取材,部分鼠经4％多聚甲醛心灌注固定,分离脊髓、制备冷冻切片;部分鼠分离脊髓、提取蛋白和RNA,分别应用免疫荧光显色、免疫印迹和RT-PCR检测Ngnl蛋白及mRNA在ALS转基因鼠发病中的变化.结果:与同窝野生型鼠比较,ALS转基因鼠Ngnl mRNA和蛋白表达在95、108 d和122 d均降低.免疫荧光实验结果显示,Ngnl阳性细胞主要分布在脊髓灰质前角,与同窝野生型鼠比较,ALS转基因鼠Ngnl阳性细胞光密度值明显减小.结论:在ALS转基因鼠发病脊髓中Ngnl阳性细胞光密度值明显减少,mRNA和蛋白表达降低,表明Ngnl与ALS的发生密切相关.     

Diffusion-weighted imaging of the entire spinal cord

In spite of their diagnostic potential, the poor quality of available diffusion-weighted spinal cord images often restricts clinical application to cervical regions, and improved spatial resolution is highly desirable. To address these needs, a novel technique based on the combination of two recently presented reduced field-of-view approaches is proposed, enabling high-resolution acquisition over the entire spinal cord. Field-of-view reduction is achieved by the application of non-coplanar excitation and refocusing pulses combined with outer volume suppression for removal of unwanted transition zones. The non-coplanar excitation is performed such that a gap-less volume is acquired in a dedicated interleaved slice order within two repetition times. The resulting inner volume selectivity was evaluated in vitro. In vivo diffusion tensor imaging data on the cervical, thoracic and lumbar spinal cord were acquired in transverse orientation in each of four healthy subjects. An in-plane resolution of 0.7 x 0.7 mm(2) was achieved without notable aliasing, motion or susceptibility artifacts. The measured mean +/- SD fractional anisotropy was 0.69 +/- 0.11 in the thoracic spinal cord and 0.75 +/- 0.07 and 0.63 +/- 0.08 in cervical and lumbar white matter, respectively.     

Pyruvate slows disease progression in a G93A SOD1 mutant transgenic mouse model

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease caused by selective motor neuron death, and currently no effective treatment is available for ALS. In this study, we investigated the neuroprotective effects of pyruvate, which acts as an anti-oxidant and as an energy source. We treated G93A SOD1 transgenic mice with pyruvate (from 70 days of age, i.p., at 1000 mg/kg/week), and found that it prolonged average lifespan by 12.3 days (10.5%), slowed disease progression, and improved motor performance, but did not delay disease onset. Pyruvate treatment was also associated with reduced nitrotyrosine immunoreactivity, gliosis, and increased Bcl-2 expression in the spinal cords of G93A SOD1 transgenic mice. These results suggest that pyruvate treatment may be a potential therapeutic strategy in ALS.     

Magnetic resonance imaging correlates of neuro‐axonal pathology in the MS spinal cord

In people with multiple sclerosis (MS), the spinal cord is the structure most commonly affected by clinically detectable pathology at presentation, and a key part of the central nervous system involved in chronic disease deterioration. Indices, such as the spinal cord cross‐sectional area at the level C₂ have been developed as tools to predict future disability, and—by inference—axonal loss. However, this and other histo‐pathological correlates of spinal cord magnetic resonance imaging (MRI) changes in MS remain incompletely understood. In recent years, there has been a surge of interest in developing quantitative MRI tools to measure specific tissue features, including axonal density, myelin content, neurite density, and orientation, among others, with an emphasis on the spinal cord. Quantitative MRI techniques including T₁ and T₂, magnetization transfer and a number of diffusion‐derived indices have all been applied to MS spinal cord. Particularly diffusion‐based MRI techniques combined with microscopic resolution achievable using high magnetic field scanners enable a new level of anatomical detail and quantification of indices that are clinically meaningful.