Genetic variability in the promoter and 3' region of the SNCA gene coding α-synuclein modulates the risk to develop sporadic Parkinson's disease (PD). Whether this is mediated by regulating ...α-synuclein expression levels remains unknown. Therefore, we analyzed levels of α-synuclein in blood and human post mortem brain tissue including the substantia nigra using quantitative real-time reverse transcriptase-polymerase chain reaction and enzyme linked immunosorbent assay in vivo. Single nucleotide polymorphism (SNP) rs356219, a tagging SNP for a disease-associated haplotype in the 3' region of the SNCA gene, has a significant effect on SNCA mRNA levels in the substantia nigra and the cerebellum. Further, the "protective" genotype 259/259 of the PD-associated promoter repeat NACP-Rep1 is associated with lower protein levels in blood than genotypes 261/261, 259/261, and 259/263. In conclusion, we provide evidence that α-synuclein levels are influenced by genetic variability in the promoter and 3' region of the SNCA gene in vivo.--Fuchs, J., Tichopad, A., Golub, Y., Munz, M., Schweitzer, K. J., Wolf, B., Berg, D., Mueller, J. C., Gasser, T. Genetic variability in the SNCA gene influences α-synuclein levels in the blood and brain.
There is increasing evidence of genetic contribution to the pathogenesis of Parkinson's disease. The identification of mutations in the leucine-rich repeat kinase 2 (LRRK2) gene has shed new light on ...genetic variations responsible for autosomal dominantly inherited Parkinson's disease. In this analysis, the most comprehensive published so far, we screened a second large series comprising 53 families with Parkinson's disease for mutations in the LRRK2 gene by direct sequencing to further determine the frequency of the mutation and evaluate the clinical phenotype to establish a genotype/phenotype relation. For comparison, all novel and known mutations were investigated in a cohort of 337 patients with apparently sporadic Parkinson's disease and a cohort of 1200 control subjects using an ABI 7900 Allelic Detection system. We identified 7 more families with LRRK2 variations in the 53 families with Parkinson's disease. Four of these are novel amino acid substitutions (R793M, Q930R, S1096C, S1228T). Because of incomplete penetrance and possible phenocopies pathogenic relevance of the Q930R and S1096C mutations as well as for the previously described A3342G splice site mutation could not be established with certainty. The so far most common mutation (G2019) was not detected in our large cohort. Late onset and typical l-dopa responsive parkinsonian features were generally observed, often accompanied by impairment of executive functions and high interference values in neuropsychological testing, as well as sleeping disturbances but rare hallucinations. There were no abnormalities in electrophysiological investigations. Distinct intrafamily and interfamily differences could be observed, including the clinical presentation of diffuse Lewy body disease in one patient. The frequent finding of cerebral atrophy on MRI and less substantia nigra hyperechogenicity compared with idiopathic Parkinson's disease on transcranial ultrasound needs to be confirmed in further studies. Together with the findings obtained in 46 families in our first study, LRRK2 mutations, therefore, account for 13% of apparently autosomal dominant families in our population with varying but still generally typical clinical presentation of Parkinson's disease.
Considering The Community Classroom Katherine SCHWEITZER
Journal of unschooling and alternative learning,
07/2015, Letnik:
9, Številka:
17
Journal Article
Odprti dostop
This is a discussion article that focuses on the limitations of the single-grade classroom in the traditional public school system. It reviews the benefits of the mixed age classroom that can be seen ...in alternative education settings. These benefits are both academic and social, as mixed-age classrooms allow for role-modeling in both of these arenas. It explores the various international examples of school systems that use mixed-age classrooms with high levels of academic success, as well as discussing the development of the current school system and how it fails to serve the needs of modern students.
OBJECTIVE:Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is caused by autosomal-dominantly inherited mutations in the colony stimulating factor 1 receptor (CSF1R) gene, and is ...clinically characterized by a progressive cognitive and motor decline leading to death within several years.
METHODS:In a continuous series of 25 patients with adult-onset leukoencephalopathy of unknown cause, we genetically confirmed HDLS in 6 families. Affected and nonaffected individuals were examined clinically and by brain MRI studies.
RESULTS:HDLS presented as prominent dementia and apraxia, often with extrapyramidal and pyramidal signs, rarely with ataxia. White matter MRI changes were detectable early in the disease course. Family history was negative in 4 of 6 index patients. In 2 of 6 index patients, we could confirm the occurrence of de novo mutations in the CSF1R gene. One family showed possible incomplete penetrancethe 69-year-old father of the index patient carried a CSF1R mutation but was clinically unaffected. In one family, the parents were apparently unaffected and not available for genetic testing.
CONCLUSIONS:Typical clinical phenotype and early brain MRI alterations can help to guide the diagnosis of HDLS. Because we confirmed de novo mutations in one-third of patients with CSF1R mutations, this diagnosis should be considered even in the absence of a family history. Furthermore, we present evidence for reduced penetrance of a CSF1R mutation. These results have substantial impact for genetic counseling of asymptomatic individuals at risk and should foster research into disease-modifying factors.
Abstract Objectives We sought to determine concentrations of total and labile iron in substantia nigra from patients with Parkinson disease and from controls to assess if oxidative stress is ...triggered by an increased concentration of iron. Methods Total iron concentration in the whole substantia nigra was evaluated in 17 parkinsonian and 29 control samples. Concentrations of labile iron and copper were assessed in 6 parkinsonian and 8 control samples. The total iron concentration, the Fe2+ /Fe3+ ratio, and iron-binding compounds were determined by Mössbauer spectroscopy. Labile iron and copper were measured by electrothermal atomic absorption spectrometry. Activity of reactive oxygen species was evaluated by visible light fluorescence. Results The labile iron concentration was significantly higher and corresponded to significantly higher reactive oxygen species activity in parkinsonian vs control samples. No significant difference was found in the total concentrations of copper or iron in the whole substantia nigra between parkinsonian and control samples. Mössbauer spectroscopy detected no Fe2+ in any samples. Conclusions The substantia nigra of parkinsonian patients contained more labile iron compared with that of controls. This labile iron generated higher reactive oxygen species activity. The oxidative stress damage in parkinsonian substantia nigra may be related to an excess of labile iron and not of the total iron in the diseased tissue.
ABSTRACTWhite matter hyperintensities (WMHs) associate with both cognitive slowing and motor dysfunction in the neurologically normal elderly. A full understanding of the pathology underlying this ...clinicoradiologic finding is currently lacking in autopsy-confirmed normal brains. To determine the histopathologic basis of WMH seen on magnetic resonance imaging, we studied the relationship between postmortem fluid-attenuated inversion recovery (FLAIR) intensity and neuropathologic markers of WM lesions (WMLs) that correspond to WMH in cognitively normal aging brains. Samples of periventricular (n = 24), subcortical (n = 26), and normal-appearing WM (NAWM, n = 31) from 4clinically and pathologically confirmed normal cases were examined. The FLAIR intensity, vacuolation, and myelin basic protein immunoreactivity loss were significantly higher in periventricular WML versus subcortical WML; both were higher than in NAWM. The subcortical WML and NAWM had significantly less axonal loss, astrocytic burden, microglial density, and oligodendrocyte loss than those of the periventricular WML. Thus, vacuolation, myelin density, and small vessel density contribute to the rarefaction of WM, whereas axonal density, oligodendrocyte density, astroglial burden, and microglial density did not. These data suggest that the age-related loss of myelin basic protein and the decrease in small vessel density may contribute to vacuolation of WM. Vacuolation enables interstitial fluid to accumulate, which contributes to the prolonged T2 relaxation and elevated FLAIR intensity in the WM.
Summary Background Increased echogenicity of the substantia nigra (SN), as determined by transcranial sonography (TCS), is characteristic of idiopathic Parkinson's disease (iPD). The results of ...initial retrospective studies indicate that this ultrasound sign is specific for iPD and can help to differentiate it from atypical parkinsonian syndromes (aPS); however, these early studies were done in patients with later disease stages and known clinical diagnosis. We aimed to determine the diagnostic value of TCS in the early stages of parkinsonian syndromes, when the clinical symptoms often do not enable a definite diagnosis to be made. Methods 60 patients who presented with the first, but still unclear, clinical symptoms of parkinsonism had TCS in this prospective blinded study. Investigators were blinded to the results of the clinical investigations, the ultrasound findings, and the diagnosis at time of investigation. The patients were followed-up every 3 months for 1 year to assess and re-evaluate the clinical symptoms. The patients in whom a clinical diagnosis could not be made with certainty were investigated with raclopride PET or dopamine transporter single-photon emission computed tomography (SPECT), or both. Findings A clinical diagnosis of parkinsonism could not be established at baseline in 38 patients. At 12 months, 39 patients were clinically categorised as having iPD. Compared with endpoint diagnosis, the sensitivity of TCS at baseline was 90%7% and the specificity was 82·4%; the positive predictive value of TCS for iPD was 92·9% and the classification accuracy was 88·3%. Interpretation TCS is an easy to implement, non-invasive, and inexpensive technique that could help in the early differential diagnosis of parkinsonian syndromes. The routine use of TCS in the clinic could enable disease-specific therapy to be started earlier. Funding Michael J Fox Foundation for Parkinson's Research.
To characterize changes in the magnetic resonance (MR) relaxation properties of progressive supranuclear palsy (PSP) and tissue from neurologically normal brains by using high-resolution (21.1-T, ...900-MHz) MR microscopy of postmortem human midbrain and basal ganglia.
This HIPAA-compliant study was approved by the institutional review board at the Mayo Clinic and informed consent was obtained. Postmortem tissue from age-matched PSP (n = 6) and control (n = 3) brains was imaged by using three-dimensional fast low-angle shot MR imaging with isotropic resolution of 50 μm. Relaxation times and parametric relaxation maps were generated from spin-echo and gradient-recalled-echo sequences. MR findings were correlated with histologic features by evaluating the presence of iron by using Prussian blue and ferritin and microglia burden as determined by a custom-designed color deconvolution algorithm. T2 and T2*, signal intensities, percent pixels (that could not be fitted in a pixel-by-pixel regression analysis due to severe hypointensity), and histologic data (total iron, ferritin, and microglia burden) were statistically analyzed by using independent sample t tests (P < .05).
PSP specimens showed higher iron burden in the cerebral peduncles and substantia nigra than did controls. However, only the putamen was significantly different, and it correlated with a decrease of T2* compared with controls (-48%; P = .043). Similarly, substantia nigra showed a significant decrease of T2* signal in PSP compared with controls (-57%; P = .028). Compared with controls, cerebral peduncles showed increased T2 (38%; P = .026) and T2* (34%; P = .014), as well as higher T2 signal intensity (57%; P = .049). Ferritin immunoreactivity was the opposite from iron burden and was significantly lower compared with controls in the putamen (-74%; P = .025), red nucleus (-61%; P = .018), and entire basal ganglia section (-63%; P = .016).
High-field-strength MR microscopy yielded pronounced differences in substantia nigra and globus pallidus of PSP compared with control brains. Histologic data also suggested that the predominant iron in PSP is hemosiderin, not ferritin. Iron in the brain is a contrast enhancer and potential biomarker for PSP.
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