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Morris CM, Valdés Aguilar R, Ghosh A, Koohpayeh SM, Krizan J, Cava RJ, Tchernyshyov O, McQueen TM, Armitage NP. Hierarchy of bound states in the one-dimensional ferromagnetic Ising chain CoNb2O6 investigated by high-resolution time-domain terahertz spectroscopy. PHYSICAL REVIEW LETTERS 2014; 112:137403. [PMID: 24745454 DOI: 10.1103/physrevlett.112.137403] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Indexed: 06/03/2023]
Abstract
Kink bound states in the one-dimensional ferromagnetic Ising chain compound CoNb2O6 have been studied using high-resolution time-domain terahertz spectroscopy in zero applied magnetic field. When magnetic order develops at low temperature, nine bound states of kinks become visible. Their energies can be modeled exceedingly well by the Airy function solutions to a 1D Schrödinger equation with a linear confining potential. This sequence of bound states terminates at a threshold energy near 2 times the energy of the lowest bound state. Above this energy scale we observe a broad feature consistent with the onset of the two particle continuum. At energies just below this threshold we observe a prominent excitation that we interpret as a novel bound state of bound states--two pairs of kinks on neighboring chains.
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Pienaar IS, Elson JL, Racca C, Nelson G, Turnbull DM, Morris CM. Mitochondrial abnormality associates with type-specific neuronal loss and cell morphology changes in the pedunculopontine nucleus in Parkinson disease. THE AMERICAN JOURNAL OF PATHOLOGY 2013; 183:1826-1840. [PMID: 24099985 DOI: 10.1016/j.ajpath.2013.09.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2013] [Revised: 08/10/2013] [Accepted: 09/04/2013] [Indexed: 01/07/2023]
Abstract
Cholinergic neuronal loss in the pedunculopontine nucleus (PPN) associates with abnormal functions, including certain motor and nonmotor symptoms. This realization has led to low-frequency stimulation of the PPN for treating patients with Parkinson disease (PD) who are refractory to other treatment modalities. However, the molecular mechanisms underlying PPN neuronal loss and the therapeutic substrate for the clinical benefits following PPN stimulation remain poorly characterized, hampering progress toward designing more efficient therapies aimed at restoring the PPN's normal functions during progressive parkinsonism. Here, we investigated postmortem pathological changes in the PPN of PD cases. Our study detected a loss of neurons producing gamma-aminobutyric acid (GABA) as their output and glycinergic neurons, along with the pronounced loss of cholinergic neurons. These losses were accompanied by altered somatic cell size that affected the remaining neurons of all neuronal subtypes studied here. Because studies showed that mitochondrial dysfunction exists in sporadic PD and in PD animal models, we investigated whether altered mitochondrial composition exists in the PPN. A significant up-regulation of several mitochondrial proteins was seen in GABAergic and glycinergic neurons; however, cholinergic neurons indicated down-regulation of the same proteins. Our findings suggest an imbalance in the activity of key neuronal subgroups of the PPN in PD, potentially because of abnormal inhibitory activity and altered cholinergic outflow.
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Nalls MA, Duran R, Lopez G, Kurzawa-Akanbi M, McKeith IG, Chinnery PF, Morris CM, Theuns J, Crosiers D, Cras P, Engelborghs S, De Deyn PP, Van Broeckhoven C, Mann DMA, Snowden J, Pickering-Brown S, Halliwell N, Davidson Y, Gibbons L, Harris J, Sheerin UM, Bras J, Hardy J, Clark L, Marder K, Honig LS, Berg D, Maetzler W, Brockmann K, Gasser T, Novellino F, Quattrone A, Annesi G, De Marco EV, Rogaeva E, Masellis M, Black SE, Bilbao JM, Foroud T, Ghetti B, Nichols WC, Pankratz N, Halliday G, Lesage S, Klebe S, Durr A, Duyckaerts C, Brice A, Giasson BI, Trojanowski JQ, Hurtig HI, Tayebi N, Landazabal C, Knight MA, Keller M, Singleton AB, Wolfsberg TG, Sidransky E. A multicenter study of glucocerebrosidase mutations in dementia with Lewy bodies. JAMA Neurol 2013; 70:727-35. [PMID: 23588557 PMCID: PMC3841974 DOI: 10.1001/jamaneurol.2013.1925] [Citation(s) in RCA: 312] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
IMPORTANCE While mutations in glucocerebrosidase (GBA1) are associated with an increased risk for Parkinson disease (PD), it is important to establish whether such mutations are also a common risk factor for other Lewy body disorders. OBJECTIVE To establish whether GBA1 mutations are a risk factor for dementia with Lewy bodies (DLB). DESIGN We compared genotype data on patients and controls from 11 centers. Data concerning demographics, age at onset, disease duration, and clinical and pathological features were collected when available. We conducted pooled analyses using logistic regression to investigate GBA1 mutation carrier status as predicting DLB or PD with dementia status, using common control subjects as a reference group. Random-effects meta-analyses were conducted to account for additional heterogeneity. SETTING Eleven centers from sites around the world performing genotyping. PARTICIPANTS Seven hundred twenty-one cases met diagnostic criteria for DLB and 151 had PD with dementia. We compared these cases with 1962 controls from the same centers matched for age, sex, and ethnicity. MAIN OUTCOME MEASURES Frequency of GBA1 mutations in cases and controls. RESULTS We found a significant association between GBA1 mutation carrier status and DLB, with an odds ratio of 8.28 (95% CI, 4.78-14.88). The odds ratio for PD with dementia was 6.48 (95% CI, 2.53-15.37). The mean age at diagnosis of DLB was earlier in GBA1 mutation carriers than in noncarriers (63.5 vs 68.9 years; P < .001), with higher disease severity scores. CONCLUSIONS AND RELEVANCE Mutations in GBA1 are a significant risk factor for DLB. GBA1 mutations likely play an even larger role in the genetic etiology of DLB than in PD, providing insight into the role of glucocerebrosidase in Lewy body disease.
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Keogh MJ, Morris CM, Chinnery PF. Neuroferritinopathy. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2013; 110:91-123. [DOI: 10.1016/b978-0-12-410502-7.00006-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
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Baron AW, Rushton SP, Rens N, Morris CM, Blain PG, Judge SJ. Sex differences in effects of low level domoic acid exposure. Neurotoxicology 2013; 34:1-8. [PMID: 23099319 DOI: 10.1016/j.neuro.2012.10.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 10/04/2012] [Accepted: 10/15/2012] [Indexed: 11/18/2022]
Abstract
Consumption of seafood containing the phytoplankton-derived toxin domoic acid (DOM) causes neurotoxicity in humans and in animals. It has been reported that DOM-induced symptoms may be more severe in men than women, but to date the effect of sex on DOM-induced effects in adults is not known. We investigated sex differences in DOM-induced effects in adult rats. Since low level exposure is of greatest relevance to human health (due to DOM regulatory limit), we examined the effects of low level exposure. Adult male and female Sprague Dawley rats were administered a single intraperitoneal injection of DOM (0, 1.0, 1.8 mg/kg). Behaviour was monitored for 3h and immunohistochemistry in the dorsal hippocampus and olfactory bulb was also examined. DOM increased locomotor and grooming activity, compared to vehicle group. DOM exposure also significantly increased stereotypic behaviours and decreased phosphorylated cAMP response element-binding protein immunoreactivity (pCREB-IR). There was no effect of sex on the magnitude of the behavioural responses, but the onset of DOM-induced locomotor activity and ear scratches was quicker in females than in males. Mixed effect modelling revealed the predicted peak in locomotor activity in response to DOM was also quicker in females than in males. Severe toxicity was evident in 2/7 male rats and 0/8 female rats dosed with 1.8 mg/kg DOM. These data suggest that males exposed to low level DOM may be more susceptible to severe neurotoxicity, whereas females are affected more quickly. Understanding sex differences in DOM-induced neurotoxicity may contribute to future protective strategies and treatments.
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Vergani F, Morris CM, Mitchell P, Duffau H. Raymond de Vieussens and his contribution to the study of white matter anatomy. J Neurosurg 2012; 117:1070-5. [DOI: 10.3171/2012.8.jns12387] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
In recent years, there has been a renewed interest in the study of white matter anatomy, both with the use of postmortem dissections and diffusion tensor imaging tractography. One of the precursors in the study of white matter anatomy was Raymond de Vieussens (1641–1716), a French anatomist born in Le Vigan. He studied medicine at the University of Montpellier in southern France, one of the most ancient and lively schools of medicine in Europe. In 1684 Vieussens published his masterpiece, the Neurographia Universalis, which is still considered one of the most complete and accurate descriptions of the nervous system provided in the 17th century. He described the white matter of the centrum ovale and was the first to demonstrate the continuity of the white matter fibers from the centrum ovale to the brainstem. He also described the dentate nuclei, the pyramids, and the olivary nuclei. According to the theory of Galen, Vieussens considered that the function of the white matter was to convey the “animal spirit” from the centrum ovale to the spinal cord. Although neglected, Vieussens' contribution to the study of white matter is relevant. His pioneering work showed that the white matter is not a homogeneous substance, but rather a complex structure rich in fibers that are interconnected with different parts of the brain. These initial results paved the way to advancements observed in later centuries that eventually led to modern hodology.
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Kurzawa-Akanbi M, Hanson PS, Blain PG, Lett DJ, McKeith IG, Chinnery PF, Morris CM. Glucocerebrosidase mutations alter the endoplasmic reticulum and lysosomes in Lewy body disease. J Neurochem 2012; 123:298-309. [PMID: 22803570 PMCID: PMC3494984 DOI: 10.1111/j.1471-4159.2012.07879.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 06/01/2012] [Accepted: 07/09/2012] [Indexed: 12/24/2022]
Abstract
Lewy body disease (LBD) development is enhanced by mutations in the GBA gene coding for glucocerebrosidase (GCase). The mechanism of this association is thought to involve an abnormal lysosomal system and we therefore sought to evaluate if lysosomal changes contribute to the pathogenesis of idiopathic LBD. Analysis of post-mortem frontal cortex tissue from 7 GBA mutation carriers with LBD, 5 GBA mutation carriers with no signs of neurological disease and human neural stem cells exposed to a GCase inhibitor was used to determine how GBA mutation contributes to LBD. GBA mutation carriers demonstrated a significantly reduced level of GCase protein and enzyme activity and retention of glucocerebrosidase isoforms within the endoplasmic reticulum (ER). This was associated with enhanced expression of the lysosomal markers LAMP1 and LAMP2, though the expression of ATP13A2 and Cathepsin D was reduced, along with the decreased activity of Cathepsin D. The ER unfolded protein response (UPR) regulator BiP/GRP78 was reduced by GBA mutation and this was a general phenomenon in LBD. Despite elevation of GRP94 in LBD, individuals with GBA mutations showed reduced GRP94 expression, suggesting an inadequate UPR. Finally, human neural stem cell cultures showed that inhibition of GCase causes acute reduction of BiP, indicating that the UPR is affected by reduced glucocerebrosidase activity. The results indicate that mutation in GBA leads to additional lysosomal abnormalities, enhanced by an impaired UPR, potentially causing α-synuclein accumulation.
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Boulton SJ, Keane PC, Morris CM, McNeil CJ, Manning P. Real-time monitoring of superoxide generation and cytotoxicity in neuroblastoma mitochondria induced by 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline. Redox Rep 2012; 17:108-14. [PMID: 22664359 DOI: 10.1179/1351000212y.0000000011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The potential neurotoxin 1-trichloromethyl-1,2,3,4-tetrahydro-beta-carboline (TaClo) has recently been suggested to be a causative factor in the clinical development of parkinsonian symptoms after long-term exposure to precursor compounds such as the hypnotic chloral hydrate. TaClo is known to cause cell death in dopaminergic neuronal cells, however, the pathway and mechanisms remain undefined. This study reports for the first time that TaClo promotes cytotoxicity in SH-SY5Y neuroblastoma cells within 2 hours of initial exposure. TaClo also caused superoxide production from isolated mitochondria, which was comparable in response time and magnitude to production elicited by more established respiratory inhibitors such as rotenone and antimycin A. These findings present new evidence in support of TaClo-induced neuronal death via superoxide signalling and oxidative stress.
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Morris CM, Aguilar RV, Stier AV, Armitage NP. Polarization modulation time-domain terahertz polarimetry. OPTICS EXPRESS 2012; 20:12303-12317. [PMID: 22714218 DOI: 10.1364/oe.20.012303] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present high precision measurements of polarization rotations in the frequency range from 0.1 to 2.5 THz using a polarization modulation technique. A motorized stage rotates a polarizer at ~ 80 Hz, and the resulting modulation of the polarization is measured by a lock-in technique. We achieve an accuracy of 0.050° (900 μrad) and a precision of 0.02° (350 μrad) for small rotation angles. A detailed mathematical description of the technique is presented, showing its ability to fully characterize elliptical polarizations from 0.1 to 2.5 THz.
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Reeve AK, Park TK, Jaros E, Campbell GR, Lax NZ, Hepplewhite PD, Krishnan KJ, Elson JL, Morris CM, McKeith IG, Turnbull DM. Relationship between mitochondria and α-synuclein: a study of single substantia nigra neurons. ACTA ACUST UNITED AC 2012; 69:385-93. [PMID: 22410447 DOI: 10.1001/archneurol.2011.2675] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To explore the relationship between α-synuclein pathology and mitochondrial respiratory chain protein levels within single substantia nigra neurons. DESIGN We examined α-synuclein and mitochondrial protein expression in substantia nigra neurons of 8 patients with dementia with Lewy bodies, 5 patients with Parkinson disease, and 8 control subjects. Protein expression was determined using immunocytochemistry followed by densometric analysis. PATIENTS We examined single substantia nigra neurons from 5 patients with idiopathic Parkinson disease (mean age, 81.2 years), 8 patients with dementia with Lewy bodies (mean age, 75 years), and 8 neurologically and pathologically normal control subjects (mean age, 74.5 years). The control cases showed minimal Lewy body pathology and cell loss. Patients with dementia with Lewy bodies and idiopathic Parkinson disease fulfilled the clinical and neuropathologic criteria for these diseases. RESULTS Our results showed that mitochondrial density is the same in nigral neurons with and without α-synuclein pathology. However, there are significantly higher levels of the respiratory chain subunits in neurons containing α-synuclein pathology. CONCLUSIONS The finding of increased levels of respiratory chain complex subunits within neurons containing α-synuclein does not support a direct association between mitochondrial respiratory chain dysfunction and the formation of α-synuclein pathology.
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Morris CM, Stehr D, Kim H, Truong TA, Pryor C, Petroff PM, Sherwin MS. Terahertz ionization of highly charged quantum posts in a perforated electron gas. NANO LETTERS 2012; 12:1115-1120. [PMID: 21517124 DOI: 10.1021/nl1044154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
"Quantum posts" are roughly cylindrical semiconductor nanostructures that are embedded in an energetically shallower "matrix" quantum well of comparable thickness. We report measurements of voltage-controlled charging and terahertz absorption of 30 nm thick InGaAs quantum wells and posts. Under flat-band (zero-electric field) conditions, the quantum posts each contain approximately six electrons, and an additional ~2.4 × 10(11) cm(-2) electrons populate the quantum well matrix. In this regime, absorption spectra show peaks at 3.5 and 4.8 THz (14 and 19 meV) whose relative amplitude depends strongly on temperature. These peaks are assigned to intersubband transitions of electrons in the quantum well matrix. A third, broader feature has a temperature-independent amplitude and is assigned to an absorption involving quantum posts. Eight-band k·p calculations incorporating the effects of strain and Coulomb repulsion predict that the electrons in the posts strongly repel the electrons in the quantum well matrix, "perforating" the electron gas. The strongest calculated transition, which has a frequency close to the center of the quantum post related absorption at 5 THz (20 meV), is an ionizing transition from a filled state to a quasi-bound state that can easily scatter to empty states in the quantum well matrix.
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Savy CY, Morris CM, Blain PG, Judge SJ. Behavioural effects of low level exposure to organophosphate pesticides. Toxicology 2011. [DOI: 10.1016/j.tox.2011.09.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Keane PC, Judge SJ, Blain PG, Morris CM. An investigation into the mechanism of trichloroethylene neurotoxicity in relation to Parkinsonism. Toxicology 2011. [DOI: 10.1016/j.tox.2011.09.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Huey ED, Ferrari R, Moreno JH, Jensen C, Morris CM, Potocnik F, Kalaria RN, Tierney M, Wassermann EM, Hardy J, Grafman J, Momeni P. FUS and TDP43 genetic variability in FTD and CBS. Neurobiol Aging 2011; 33:1016.e9-17. [PMID: 21943958 DOI: 10.1016/j.neurobiolaging.2011.08.004] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2011] [Revised: 07/26/2011] [Accepted: 08/05/2011] [Indexed: 12/12/2022]
Abstract
This study aimed to evaluate genetic variability in the FUS and TDP-43 genes, known to be mainly associated with amyotrophic lateral sclerosis (ALS), in patients with the diagnoses of frontotemporal lobar degeneration (FTLD) and corticobasal syndrome (CBS). We screened the DNA of 228 patients for all the exons and flanking introns of FUS and TDP-43 genes. We identified 2 novel heterozygous missense mutations in FUS: P106L (g.22508384C>T) in a patient with behavioral variant frontotemporal dementia (bvFTD) and Q179H in several members of a family with behavioral variant FTD. We also identified the N267S mutation in TDP-43 in a CBS patient, previously only reported in 1 ALS family and 1 FTD patient. Additionally, we identified 2 previously reported heterozygous insertion and deletion mutations in Exon 5 of FUS; Gly174-Gly175 del GG (g. 4180-4185 delGAGGTG) in an FTD patient and Gly175-Gly176 ins GG (g. 4185-4186 insGAGGTG) in a patient with diagnosis of CBS. Not least, we have found a series of variants in FUS also in neurologically normal controls. In summary, we report that genetic variability in FUS and TDP-43 encompasses a wide range of phenotypes (including ALS, FTD, and CBS) and that there is substantial genetic variability in FUS gene in neurologically normal controls.
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Keane PC, Kurzawa M, Blain PG, Morris CM. Mitochondrial dysfunction in Parkinson's disease. PARKINSONS DISEASE 2011; 2011:716871. [PMID: 21461368 PMCID: PMC3065167 DOI: 10.4061/2011/716871] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 01/03/2011] [Accepted: 01/16/2011] [Indexed: 12/21/2022]
Abstract
Parkinson's disease (PD) is a progressive, neurodegenerative condition that has increasingly been linked with mitochondrial dysfunction and inhibition of the electron transport chain. This inhibition leads to the generation of reactive oxygen species and depletion of cellular energy levels, which can consequently cause cellular damage and death mediated by oxidative stress and excitotoxicity. A number of genes that have been shown to have links with inherited forms of PD encode mitochondrial proteins or proteins implicated in mitochondrial dysfunction, supporting the central involvement of mitochondria in PD. This involvement is corroborated by reports that environmental toxins that inhibit the mitochondrial respiratory chain have been shown to be associated with PD.
This paper aims to illustrate the considerable body of evidence linking mitochondrial dysfunction with neuronal cell death in the substantia nigra pars compacta (SNpc) of PD patients and to highlight the important need for further research in this area.
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Stehr D, Morris CM, Schmidt C, Sherwin MS. High-performance fiber-laser-based terahertz spectrometer. OPTICS LETTERS 2010; 35:3799-3801. [PMID: 21082001 DOI: 10.1364/ol.35.003799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We have developed a rapid scanning terahertz (THz) spectrometer based on a synchronized two-fiber-laser system. When the system is set to the asynchronous optical sampling mode, THz spectra extending to 3 THz can be acquired within 1 μs at a signal-to-noise ratio of the electric field of better than 20. Signal averaging results in a dynamic range of more than 60 dB, and frequency components of more than 4 THz can be detected. When the lasers are set to the same repetition rate, electronically controlled optical sampling at a rate of 2.5 kHz is demonstrated, making the system versatile for different spectroscopic applications. Finally, we compare the THz emission spectra of a photoconductive switch that is pumped at 780 nm and a nonlinear DAST crystal excited at 1550 nm. We find that the spectral range of the spectrometer is significantly enhanced at higher frequencies, while the dynamic range remains constant.
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Morris CM, Ballard CG, Allan L, Rowan E, Stephens S, Firbank M, Ford GA, Kenny RA, O'Brien JT, Kalaria RN. NOS3 gene rs1799983 polymorphism and incident dementia in elderly stroke survivors. Neurobiol Aging 2010; 32:554.e1-6. [PMID: 20691505 DOI: 10.1016/j.neurobiolaging.2010.06.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2009] [Revised: 05/20/2010] [Accepted: 06/21/2010] [Indexed: 11/25/2022]
Abstract
Stroke is a major risk factor for the development of dementia in the elderly. It is unclear which genes influence risk of delayed dementia after stroke. We tested a single nucleotide polymorphism (SNP) in endothelial nitric oxide synthase (NOS3) gene at codon 298 (single-nucleotide polymorphism rs1799983; p.Asp298Glu) in a cohort of 355 older (>75 years) stroke survivors, who had detailed cognitive assessments from 3 months poststroke, i.e., baseline when the patients were free of dementia and subsequently at annual intervals. Of these, 253 participants were genotyped for polymorphisms in NOS3 and apolipoprotein E (APOE). Our analysis showed that homozygosity for NOS3 TT rather than the GT or GG genotype was a significant factor in the development of dementia. The presence of TT genotype increased risk of incident dementia compared with GG genotype; hazard ratio, 3.14 (95% confidence interval, 1.64-5.99; p = 0.001). We hypothesize that this may be mediated by reduction of nitric oxide production and cerebral perfusion. Our findings, if replicated widely, have implications for treatments to ameliorate cognitive decline in stroke survivors.
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Elstner M, Morris CM, Heim K, Lichtner P, Bender A, Mehta D, Schulte C, Sharma M, Hudson G, Goldwurm S, Giovanetti A, Zeviani M, Burn DJ, McKeith IG, Perry RH, Jaros E, Krüger R, Wichmann HE, Schreiber S, Campbell H, Wilson JF, Wright AF, Dunlop M, Pistis G, Toniolo D, Chinnery PF, Gasser T, Klopstock T, Meitinger T, Prokisch H, Turnbull DM. Single-cell expression profiling of dopaminergic neurons combined with association analysis identifies pyridoxal kinase as Parkinson's disease gene. Ann Neurol 2010; 66:792-8. [PMID: 20035503 DOI: 10.1002/ana.21780] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE The etiology of Parkinson disease (PD) is complex and multifactorial, with hereditary and environmental factors contributing. Monogenic forms have provided molecular clues to disease mechanisms but genetic modifiers of idiopathic PD are still to be determined. METHODS We carried out whole-genome expression profiling of isolated human substantia nigra (SN) neurons from patients with PD vs. controls followed by association analysis of tagging single-nucleotide polymorphisms (SNPs) in differentially regulated genes. Association was investigated in a German PD sample and confirmed in Italian and British cohorts. RESULTS We identified four differentially expressed genes located in PD candidate pathways, ie, MTND2 (mitochondrial, p = 7.14 x 10(-7)), PDXK (vitamin B6/dopamine metabolism, p = 3.27 x 10(-6)), SRGAP3 (axon guidance, p = 5.65 x 10(-6)), and TRAPPC4 (vesicle transport, p = 5.81 x 10(-6)). We identified a DNA variant (rs2010795) in PDXK associated with an increased risk of PD in the German cohort (p = 0.00032). This association was confirmed in the British (p = 0.028) and Italian (p = 0.0025) cohorts individually and reached a combined value of p = 1.2 x 10(-7) (odds ratio [OR], 1.3; 95% confidence interval [CI], 1.18-1.44). INTERPRETATION We provide an example of how microgenomic genome-wide expression studies in combination with association analysis can aid to identify genetic modifiers in neurodegenerative disorders. The detection of a genetic variant in PDXK, together with evidence accumulating from clinical studies, emphasize the impact of vitamin B6 status and metabolism on disease risk and therapy in PD.
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Reeve AK, Krishnan KJ, Taylor G, Elson JL, Bender A, Taylor RW, Morris CM, Turnbull DM. The low abundance of clonally expanded mitochondrial DNA point mutations in aged substantia nigra neurons. Aging Cell 2009; 8:496-8. [PMID: 19489744 PMCID: PMC2759982 DOI: 10.1111/j.1474-9726.2009.00492.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Clonally expanded mitochondrial DNA (mtDNA) deletions accumulate with age in human substantia nigra (SN) and high levels cause respiratory chain deficiency. In other human tissues, mtDNA point mutations clonally expand with age. Here, the abundance of mtDNA point mutations within single SN neurons from aged controls was investigated. From 31 single cytochrome c oxidase normal SN neurons, only one clonally expanded mtDNA point mutation was identified, suggesting in these neurons mtDNA point mutations occur rarely, whereas mtDNA deletions are frequently observed. This contrasts observations in mitotic tissues and suggests that different forms of mtDNA maintenance may exist in these two cell types.
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Reeve AK, Krishnan KJ, Elson JL, Morris CM, Bender A, Lightowlers RN, Turnbull DM. Nature of mitochondrial DNA deletions in substantia nigra neurons. Am J Hum Genet 2008; 82:228-35. [PMID: 18179904 DOI: 10.1016/j.ajhg.2007.09.018] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2007] [Revised: 09/04/2007] [Accepted: 09/13/2007] [Indexed: 01/07/2023] Open
Abstract
Mitochondrial DNA (mtDNA) deletions have been investigated in a number of neurodegenerative diseases. This study aimed to investigate the characteristics of mtDNA deletions found in single substantia nigra neurons from three patient groups: controls, Parkinson disease patients, and a patient with Parkinsonism due to multiple mtDNA deletions. We have identified 89 deletions from these neurons and examined the breakpoint characteristics of them. There was no difference in the types of mtDNA deletions detected in these neurons. These results suggest that the mechanism leading to the formation of these deletions in these three distinct groups could be the same.
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Edwardson JA, Candy JM, Ince PG, McArthur FK, Morris CM, Oakley AE, Taylor GA, Bjertness E. Aluminium accumulation, beta-amyloid deposition and neurofibrillary changes in the central nervous system. CIBA FOUNDATION SYMPOSIUM 2007; 169:165-79; discussion 179-85. [PMID: 1490421 DOI: 10.1002/9780470514306.ch10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Deposition of beta-amyloid and the formation of neurofibrillary tangles (NFTs) are central to the aetiopathogenesis of Alzheimer's disease (AD). The possible effects of aluminium on these processes have been investigated in patients with renal failure who are exposed chronically to high blood levels of aluminium. Focal accumulation of aluminium was observed in neurons with high densities of transferrin receptors, indicating transferrin-mediated uptake, in regions such as cortex and hippocampus which are selectively vulnerable in AD. Increased staining for the beta-amyloid precursor protein (APP) in cortical pyramidal neurons was evident in the majority of renal patients and immature senile plaques were present in 30% of cases, suggesting that aluminium may induce or accelerate beta-amyloid deposition. The absence of neurofibrillary changes in this group of renal patients indicates that aluminium does not directly cause the formation of NFTs. The brain aluminium content was not raised in neuropathologically assessed cases of AD and we have been unable to confirm claims of defective transferrin binding in this disorder. If aluminium contributes to the development of sporadic AD, it must do so indirectly, perhaps via effects on the synthesis or metabolism of APP, or by contributing generally to the age-related attrition of neurons and thus reducing the threshold for deficits produced by more specific disease-related processes.
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Morris CM, Tefuarani N, Ripa P, Laki R, Vince JD. Urinary tract infection in infants and young children presenting with fever without a focus in Port Moresby. PAPUA AND NEW GUINEA MEDICAL JOURNAL 2007; 50:145-151. [PMID: 19583097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A prospective study was undertaken to document the importance of urinary tract infection (UTI) as a cause of fever without a focus (FWF) in children less than 3 years of age presenting to the Children's Outpatients Department (COPD) of Port Moresby General Hospital (PMGH). 98 children, 55 males and 43 females, with a median age of 17 months and an interquartile range of 5-31.25 months, were recruited. In addition to a history and physical examination each child had a full blood count, a malaria parasite smear, and a urine sample (obtained by clean catch or midstream methods) for dipstick testing, microscopy and culture. Blood culture was performed where practicable. Lumbar puncture and cerebrospinal fluid (CSF) examination were done only if clinically indicated. UTI was diagnosed on urine culture in 9 of the 98 children. Both urinary nitrite and leukocyte esterase tests were sensitive (89%) and specific (96%). Other causes of FWF were classified as non-specific viral infection (31 children), lower respiratory tract infection (11), malaria (7), meningitis (4), bacteraemia (1 neonate) and other or unknown causes. The finding of UTI in 9% of the children is consistent with data from other tropical countries. Checking for urinary tract infection, which can be done using noninvasive methods of urine collection, is an important part of the investigation of infants and children with FWF.
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Oakley AE, Collingwood JF, Dobson J, Love G, Perrott HR, Edwardson JA, Elstner M, Morris CM. Individual dopaminergic neurons show raised iron levels in Parkinson disease. Neurology 2007; 68:1820-5. [PMID: 17515544 DOI: 10.1212/01.wnl.0000262033.01945.9a] [Citation(s) in RCA: 204] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Evidence suggests that abnormal iron metabolism is associated with Parkinson disease (PD), with raised iron levels found in pathologically affected areas in PD. It is unknown if this elevated iron is actually associated with neurons or reactive glia, and we therefore addressed this issue by determining if raised iron was present in single dopaminergic neurons. METHODS We used unfixed frozen sections from postmortem tissue of PD patients and elderly normal individuals to avoid metal contamination and translocation. Levels of iron and other elements were measured using sensitive and specific wavelength dispersive electron probe x-ray microanalysis coupled with cathodoluminescence spectroscopy in individual substantia nigra dopaminergic neurons. RESULTS We identified raised intraneuronal iron in single defined substantia nigra neurons in PD (mean neuronal iron 2,838 vs 1,611, p < 0.0001) but not in other movement disorders such as Huntington disease. These findings were unrelated to the density of remaining neurons. CONCLUSIONS Primary changes in neuronal iron could lead to neurodegeneration in Parkinson disease.
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He J, Krenner HJ, Pryor C, Zhang JP, Wu Y, Allen DG, Morris CM, Sherwin MS, Petroff PM. Growth, structural, and optical properties of self-assembled (In,Ga)as quantum posts on GaAs. NANO LETTERS 2007; 7:802-6. [PMID: 17326694 DOI: 10.1021/nl070132r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Self-assembled quantum dots embedded in semiconductor heterostructures have proved to be a rich system for exploring the physics of three dimensionally confined charges and excitons. We present here a novel structure, which allows adjusting the level of confinement between 3D and 2D for electrons and holes, respectively. The quantum post consists of a quantum dot connected to a short quantum wire. The molecular beam epitaxy deposition of these self-assembled structures is discussed, and their structural and chemical compositions are presented. Their optical properties measured by photoluminescence are compared to an eight-band strain-dependent k.p model incorporating detailed structure and alloy composition. The calculations show electron delocalization in the quantum wire part of the quantum post and hole localization in the strain-induced regions at the ends of the quantum post. The quantum post offers the possibility of controlling the dipole moment in the structure and opens up new means for tuning the intra-subband transitions by controlling its dimensions.
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Low WC, Junna M, Börjesson-Hanson A, Morris CM, Moss TH, Stevens DL, St Clair D, Mizuno T, Zhang WW, Mykkänen K, Wahlstrom J, Andersen O, Kalimo H, Viitanen M, Kalaria RN. Hereditary multi-infarct dementia of the Swedish type is a novel disorder different from NOTCH3 causing CADASIL. Brain 2007; 130:357-67. [PMID: 17235124 DOI: 10.1093/brain/awl360] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Several hereditary small vessel diseases (SVDs) of the brain have been reported in recent years. In 1977, Sourander and Wålinder described hereditary multi-infarct dementia (MID) in a Swedish family. In the same year, Stevens and colleagues reported chronic familial vascular encephalopathy in an English family bearing a similar phenotype. These disorders have invariably been suggested to be cerebral autosomal dominant arteriopathy with subcortical infarcts and leucoencephalopathy (CADASIL) but their genetic identities remain unknown. We used molecular, radiological and neuropathological methods to characterize these disorders. Direct DNA sequencing unexpectedly confirmed that affected members of the English family carried the R141C mutation in the NOTCH3 gene diagnostic of CADASIL. However, we did not detect any pathogenic mutations in the entire 8091 bp reading frame of NOTCH3 or find clear evidence for NOTCH3 gene linkage in the Swedish DNA. This was consistent with the lack of hyperintense signals in the anterior temporal pole and external capsule in Swedish subjects upon magnetic resonance imaging. We further found no evidence for granular osmiophilic material in skin biopsy or post-mortem brain samples of affected members in the Swedish family. In addition, there was distinct lack of NOTCH3 N-terminal fragments in the cerebral microvasculature of the Swedish hereditary MID subjects compared to the intense accumulation in the English family afflicted with CADASIL. Several differences in arteriosclerotic changes in both the grey and white matter were also noted between the disorders. The sclerotic index values, density of collagen IV immunoreactivity in the microvasculature and number of perivascular macrophages were greater in the English CADASIL samples compared to those from the Swedish brains. Multiple approaches suggest that the Swedish family with hereditary MID suspected to be CADASIL has a different novel disorder with dissimilar pathological features and belongs to the growing number of genetically uncharacterized familial SVDs.
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