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Find video protocols related to scientific articles indexed in Pubmed.
Synthetic Analogues of the Marine Bisindole Deoxytopsentin: Potent Selective Inhibitors of MRSA Pyruvate Kinase.
J. Nat. Prod.
PUBLISHED: 11-06-2014
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As part of an ongoing study to elucidate the SAR of bisindole alkaloid inhibitors against the evolutionary conserved MRSA pyruvate kinase (PK), we present here the synthesis and biological activity of six dihalogenated analogues of the naturally occurring sponge metabolite deoxytopsentin, including the naturally occurring dibromodeoxytopsentin. The most active compounds displayed potent low nanomolar inhibitory activity against MRSA PK with concomitant significant selectivity for MRSA PK over human PK orthologues. Computational studies suggest that these potent MRSA PK inhibitors occupy a region of the small interface of the enzyme tetramer where amino acid sequence divergence from common human PK orthologues may contribute to the observed selectivity.
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Identification of Palmitoyltransferase and Thioesterase Enzymes that Control the Subcellular Localisation of Axon Survival Factor Nicotinamide Mononucleotide Adenylyltransferase 2 (NMNAT2).
J. Biol. Chem.
PUBLISHED: 09-30-2014
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The NAD-synthesising enzyme NMNAT2 is a critical survival factor for axons and its constant supply from neuronal cell bodies into axons is required for axon survival in primary culture neurites and for axon extension in vivo. Recently, we showed that palmitoylation is necessary to target NMNAT2 to post-Golgi vesicles, thereby influencing its protein turnover and axon protective capacity. Here we find that NMNAT2 is a substrate for the cytosolic thioesterases APT1 and APT2 and that palmitoylation/depalmitoylation dynamics are on a timescale similar to its short half-life. Interestingly, however, depalmitoylation does not release NMNAT2 from membranes. The mechanism of palmitoylation-independent membrane attachment appears to be mediated by the same minimal domain required for palmitoylation itself. Furthermore, we identify several zDHHC palmitoyltransferases that influence NMNAT2 palmitoylation and subcellular localisation, among which a role for zDHHC17 (HIP14) in neuronal NMNAT2 palmitoylation is best supported by our data. These findings shed light on the enzymatic regulation of NMNAT2 palmitoylation and highlight individual thioesterases and palmitoyltransferases as potential targets to modulate NMNAT2-dependent axon survival.
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Wallerian degeneration: an emerging axon death pathway linking injury and disease.
Nat. Rev. Neurosci.
PUBLISHED: 05-21-2014
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Axon degeneration is a prominent early feature of most neurodegenerative disorders and can also be induced directly by nerve injury in a process known as Wallerian degeneration. The discovery of genetic mutations that delay Wallerian degeneration has provided insight into mechanisms underlying axon degeneration in disease. Rapid Wallerian degeneration requires the pro-degenerative molecules SARM1 and PHR1. Nicotinamide mononucleotide adenylyltransferase 2 (NMNAT2) is essential for axon growth and survival. Its loss from injured axons may activate Wallerian degeneration, whereas NMNAT overexpression rescues axons from degeneration. Here, we discuss the roles of these and other proposed regulators of Wallerian degeneration, new opportunities for understanding disease mechanisms and intriguing links between Wallerian degeneration, innate immunity, synaptic growth and cell death.
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Age-related axonal swellings precede other neuropathological hallmarks in a knock-in mouse model of Huntington's disease.
Neurobiol. Aging
PUBLISHED: 04-20-2014
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Axon degeneration precedes cell body death in many age-related neurodegenerative disorders, often determining symptom onset and progression. A sensitive method for revealing axon pathology could indicate whether this is the case also in Huntington's disease (HD), a fatal, devastating neurodegenerative disorder causing progressive deterioration of both physical and mental abilities, and which brain region is affected first. We studied the spatio-temporal relationship between axon pathology, neuronal loss, and mutant Huntingtin aggregate formation in HD mouse models by crossing R6/2 transgenic and HdhQ140 knock-in mice with YFP-H mice expressing the yellow fluorescent protein in a subset of neurons. We found large axonal swellings developing age-dependently first in stria terminalis and then in corticostriatal axons of HdhQ140 mice, whereas alterations of other neuronal compartments could not be detected. Although mutant Huntingtin accumulated with age in several brain areas, inclusions in the soma did not correlate with swelling of the corresponding axons. Axon abnormalities were not a prominent feature of the rapid progressive pathology of R6/2 mice. Our findings in mice genetically similar to HD patients suggest that axon pathology is an early event in HD and indicate the importance of further studies of stria terminalis axons in man.
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Two sides of the same coin: stem cells in cancer and regenerative medicine.
FASEB J.
PUBLISHED: 03-27-2014
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Multipotent stromal cells (MSCs) derived from bone marrow, adipose tissue, cord blood, and other origins have recently received much attention as potential therapeutic agents with beneficial immunomodulatory and regenerative properties. In their native tissue environment, however, such cells also appear to have essential functions in building and supporting tumor microenvironments, providing metastatic niches, and maintaining cancer hallmarks. Here, we consider the varied roles of these tissue-resident stroma-associated cells, synthesize recent and emerging discoveries, and discuss the role, potential, and clinical applications of MSCs in cancer and regenerative medicine.-Ilmer, M., Vykoukal, J., Recio Boiles, A., Coleman, M., Alt, E. Two sides of the same coin: stem cells in cancer and regenerative medicine.
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The Axon-Protective WLD(S) Protein Partially Rescues Mitochondrial Respiration and Glycolysis After Axonal Injury.
J. Mol. Neurosci.
PUBLISHED: 03-05-2014
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The axon-protective Wallerian degeneration slow (WLD(S)) protein can ameliorate the decline in axonal ATP levels after neurite transection. Here, we tested the hypothesis that this effect is associated with maintenance of mitochondrial respiration and/or glycolysis. We used isolated neurites of superior cervical ganglion (SCG) cultures in the Seahorse XF-24 Metabolic Flux Analyser to determine mitochondrial respiration and glycolysis under different conditions. We observed that both mitochondrial respiration and glycolysis declined significantly during the latent phase of Wallerian degeneration. WLD(S) partially reduced the decline both in glycolysis and in mitochondrial respiration. In addition, we found that depleting NAD levels in uncut cultures led to changes in mitochondrial respiration and glycolysis similar to those rescued by WLD(S) after cut, suggesting that the maintenance of NAD levels in Wld (S) neurites after axonal injury at least partially underlies the maintenance of ATP levels. However, by using another axon-protective mutation (Sarm1 (-/-)), we could demonstrate that rescue of basal ECAR (and hence probably glycolysis) rather than basal OCR (mitochondrial respiration) may be part of the protective phenotype to delay Wallerian degeneration. These findings open new routes to study glycolysis and the connection between NAD and ATP levels in axon degeneration, which may help to eventually develop therapeutic strategies to treat neurodegenerative diseases.
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A country on the verge of malaria elimination--the Kingdom of Saudi Arabia.
PLoS ONE
PUBLISHED: 01-01-2014
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Significant headway has been made in the global fight against malaria in the past decade and as more countries enter the elimination phase, attention is now focused on identifying effective strategies to shrink the malaria map. Saudi Arabia experienced an outbreak of malaria in 1998, but is now on the brink of malaria elimination, with just 82 autochthonous cases reported in 2012. A review of published and grey literature was performed to identify the control strategies that have contributed to this achievement. The number of autochthonous malaria cases in Saudi Arabia decreased by 99.8% between 1998 and 2012. The initial steep decline in malaria cases coincided with a rapid scaling up of vector control measures. Incidence continued to be reported at low levels (between 0.01 and 0.1 per 1,000 of the population) until the adoption of artesunate plus sulfadoxine-pyrimethamine as first line treatment and the establishment of a regional partnership for a malaria-free Arabian Peninsula, both of which occurred in 2007. Since 2007, incidence has decreased by nearly an order of magnitude. Malaria incidence is now very low, but a high proportion of imported cases, continued potential for autochthonous transmission, and an increased proportion of cases attributable to Plasmodium vivax all present challenges to Saudi Arabia as they work toward elimination by 2015.
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Underpinning sustainable vector control through informed insecticide resistance management.
PLoS ONE
PUBLISHED: 01-01-2014
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There has been rapid scale-up of malaria vector control in the last ten years. Both of the primary control strategies, long-lasting pyrethroid treated nets and indoor residual spraying, rely on the use of a limited number of insecticides. Insecticide resistance, as measured by bioassay, has rapidly increased in prevalence and has come to the forefront as an issue that needs to be addressed to maintain the sustainability of malaria control and the drive to elimination. Zambia's programme reported high levels of resistance to the insecticides it used in 2010, and, as a result, increased its investment in resistance monitoring to support informed resistance management decisions.
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Clinical oxidative stress during leprosy multidrug therapy: impact of dapsone oxidation.
PLoS ONE
PUBLISHED: 01-01-2014
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This study aims to assess the oxidative stress in leprosy patients under multidrug therapy (MDT; dapsone, clofazimine and rifampicin), evaluating the nitric oxide (NO) concentration, catalase (CAT) and superoxide dismutase (SOD) activities, glutathione (GSH) levels, total antioxidant capacity, lipid peroxidation, and methemoglobin formation. For this, we analyzed 23 leprosy patients and 20 healthy individuals from the Amazon region, Brazil, aged between 20 and 45 years. Blood sampling enabled the evaluation of leprosy patients prior to starting multidrug therapy (called MDT 0) and until the third month of multidrug therapy (MDT 3). With regard to dapsone (DDS) plasma levels, we showed that there was no statistical difference in drug plasma levels between multibacillary (0.518±0.029 µg/mL) and paucibacillary (0.662±0.123 µg/mL) patients. The methemoglobin levels and numbers of Heinz bodies were significantly enhanced after the third MDT-supervised dose, but this treatment did not significantly change the lipid peroxidation and NO levels in these leprosy patients. In addition, CAT activity was significantly reduced in MDT-treated leprosy patients, while GSH content was increased in these patients. However, SOD and Trolox equivalent antioxidant capacity levels were similar in patients with and without treatment. These data suggest that MDT can reduce the activity of some antioxidant enzyme and influence ROS accumulation, which may induce hematological changes, such as methemoglobinemia in patients with leprosy. We also explored some redox mechanisms associated with DDS and its main oxidative metabolite DDS-NHOH and we explored the possible binding of DDS to the active site of CYP2C19 with the aid of molecular modeling software.
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Axonal trafficking of NMNAT2 and its roles in axon growth and survival in vivo.
Bioarchitecture
PUBLISHED: 11-07-2013
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The NAD-synthesizing enzyme NMNAT2 is critical for axon survival in primary culture and its depletion may contribute to axon degeneration in a variety of neurodegenerative disorders. Here we discuss several recent reports from our laboratory that establish a critical role for NMNAT2 in axon growth in vivo in mice and shed light on the delivery and turnover of this survival factor in axons. In the absence of NMNAT2, axons fail to extend more than a short distance beyond the cell body during embryonic development, implying a requirement for NMNAT2 in axon maintenance even during development. Furthermore, we highlight findings regarding the bidirectional trafficking of NMNAT2 in axons on a vesicle population that undergoes fast axonal transport in primary culture neurites and in mouse sciatic nerve axons in vivo. Surprisingly, loss of vesicle association boosts the axon protective capacity of NMNAT2, an effect that is at least partially mediated by a longer protein half-life of cytosolic NMNAT2 variants. Analysis of wild-type and variant NMNAT2 in mouse sciatic nerves and Drosophila olfactory receptor neuron axons supports the existence of a similar mechanism in vivo, highlighting the potential for regulation of NMNAT2 stability and turnover as a mechanism to modulate axon degeneration in vivo.
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Efficient and regioselective nickel-catalyzed [2 + 2 + 2] cyclotrimerization of ynoates and related alkynes.
Org. Biomol. Chem.
PUBLISHED: 10-16-2013
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A nickel-based catalytic system has been developed for [2 + 2 + 2] cyclotrimerization of various alkynes, especially ynoates. This catalytic system enables facile construction of substituted aromatic compounds in excellent yields with high regioselectivity.
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Rescue of peripheral and CNS axon defects in mice lacking NMNAT2.
J. Neurosci.
PUBLISHED: 08-16-2013
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NMNAT2 is an NAD(+)-synthesizing enzyme with an essential axon maintenance role in primary culture neurons. We have generated an Nmnat2 gene trap mouse to examine the role of NMNAT2 in vivo. Homozygotes die perinatally with a severe peripheral nerve/axon defect and truncated axons in the optic nerve and other CNS regions. The cause appears to be limited axon extension, rather than dying-back degeneration of existing axons, which was previously proposed for the NMNAT2-deficient Blad mutant mouse. Neurite outgrowth in both PNS and CNS neuronal cultures consistently stalls at 1-2 mm, similar to the length of truncated axons in the embryos. Crucially, this suggests an essential role for NMNAT2 during axon growth. In addition, we show that the Wallerian degeneration slow protein (Wld(S)), a more stable, aberrant NMNAT that can substitute the axon maintenance function of NMNAT2 in primary cultures, can also correct developmental defects associated with NMNAT2 deficiency. This is dose-dependent, with extension of life span to at least 3 months by homozygous levels of Wld(S) the most obvious manifestation. Finally, we propose that endogenous mechanisms also compensate for otherwise limiting levels of NMNAT2. This could explain our finding that conditional silencing of a single Nmnat2 allele triggers substantial degeneration of established neurites, whereas similar, or greater, reduction of NMNAT2 in constitutively depleted neurons is compatible with normal axon growth and survival. A requirement for NMNAT2 for both axon growth and maintenance suggests that reduced levels could impair axon regeneration as well as axon survival in aging and disease.
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Deletions within its subcellular targeting domain enhance the axon protective capacity of Nmnat2 in vivo.
Sci Rep
PUBLISHED: 06-13-2013
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The NAD-synthesising enzyme Nmnat2 is a critical survival factor for axons in vitro and in vivo. We recently reported that loss of axonal transport vesicle association through mutations in its isoform-specific targeting and interaction domain (ISTID) reduces Nmnat2 ubiquitination, prolongs its half-life and boosts its axon protective capacity in primary culture neurons. Here, we report evidence for a role of ISTID sequences in tuning Nmnat2 localisation, stability and protective capacity in vivo. Deletion of central ISTID sequences abolishes vesicle association and increases protein stability of fluorescently tagged, transgenic Nmnat2 in mouse peripheral axons in vivo. Overexpression of fluorescently tagged Nmnat2 significantly delays Wallerian degeneration in these mice. Furthermore, while mammalian Nmnat2 is unable to protect transected Drosophila olfactory receptor neuron axons in vivo, mutant Nmnat2s lacking ISTID regions substantially delay Wallerian degeneration. Together, our results establish Nmnat2 localisation and turnover as a valuable target for modulating axon degeneration in vivo.
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The challenges of axon survival: introduction to the special issue on axonal degeneration.
Exp. Neurol.
PUBLISHED: 06-12-2013
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Early axon loss is a common feature of many neurodegenerative disorders. It renders neurons functionally inactive, or less active if axon branches are lost, in a manner that is often irreversible. In the CNS, there is no long-range axon regeneration and even peripheral nerve axons are unlikely to reinnervate their targets while the cause of the problem persists. In most disorders, axon degeneration precedes cell death so it is not simply a consequence of it, and it is now clear that axons have at least one degeneration mechanism that differs from that of the soma. It is important to understand these degeneration mechanisms and their contribution to axon loss in neurodegenerative disorders. In this way, it should become possible to prevent axon loss as well as cell death. This special edition considers the roles and mechanisms of axon degeneration in amyotrophic lateral sclerosis, Charcot-Marie-Tooth disease, hereditary spastic paraplegia, ischemic injury, traumatic brain injury, Alzheimers disease, glaucoma, Huntingtons disease and Parkinsons disease. Using examples from these and other disorders, this introduction considers some of the reasons for axon vulnerability. It also illustrates how molecular genetics and studies of Wallerian degeneration have contributed to our understanding of axon degeneration mechanisms.
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Genetic contributions to changes of fiber tracts of ventral visual stream in 22q11.2 deletion syndrome.
Brain Imaging Behav
PUBLISHED: 04-25-2013
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Patients with 22q11.2 deletion syndrome (22q11.2DS) represent a population at high risk for developing schizophrenia, as well as learning disabilities. Deficits in visuo-spatial memory are thought to underlie some of the cognitive disabilities. Neuronal substrates of visuo-spatial memory include the inferior fronto-occipital fasciculus (IFOF) and the inferior longitudinal fasciculus (ILF), two tracts that comprise the ventral visual stream. Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) is an established method to evaluate white matter (WM) connections in vivo. DT-MRI scans of nine 22q11.2DS young adults and nine matched healthy subjects were acquired. Tractography of the IFOF and the ILF was performed. DT-MRI indices, including Fractional anisotropy (FA, measure of WM changes), axial diffusivity (AD, measure of axonal changes) and radial diffusivity (RD, measure of myelin changes) of each of the tracts and each group were measured and compared. The 22q11.2DS group showed statistically significant reductions of FA in IFOF in the left hemisphere. Additionally, reductions of AD were found in the IFOF and the ILF in both hemispheres. These findings might be the consequence of axonal changes, which is possibly due to fewer, thinner, or less organized fibers. No changes in RD were detected in any of the tracts delineated, which is in contrast to findings in schizophrenia patients where increases in RD are believed to be indicative of demyelination. We conclude that reduced axonal changes may be key to understanding the underlying pathology of WM leading to the visuo-spatial phenotype in 22q11.2DS.
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Subcellular localization determines the stability and axon protective capacity of axon survival factor Nmnat2.
PLoS Biol.
PUBLISHED: 04-01-2013
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Axons require a constant supply of the labile axon survival factor Nmnat2 from their cell bodies to avoid spontaneous axon degeneration. Here we investigate the mechanism of fast axonal transport of Nmnat2 and its site of action for axon maintenance. Using dual-colour live-cell imaging of axonal transport in SCG primary culture neurons, we find that Nmnat2 is bidirectionally trafficked in axons together with markers of the trans-Golgi network and synaptic vesicles. In contrast, there is little co-migration with mitochondria, lysosomes, and active zone precursor vesicles. Residues encoded by the small, centrally located exon 6 are necessary and sufficient for stable membrane association and vesicular axonal transport of Nmnat2. Within this sequence, a double cysteine palmitoylation motif shared with GAP43 and surrounding basic residues are all required for efficient palmitoylation and stable association with axonal transport vesicles. Interestingly, however, disrupting this membrane association increases the ability of axonally localized Nmnat2 to preserve transected neurites in primary culture, while re-targeting the strongly protective cytosolic mutants back to membranes abolishes this increase. Larger deletions within the central domain including exon 6 further enhance Nmnat2 axon protective capacity to levels that exceed that of the slow Wallerian degeneration protein, Wld(S). The mechanism underlying the increase in axon protection appears to involve an increased half-life of the cytosolic forms, suggesting a role for palmitoylation and membrane attachment in Nmnat2 turnover. We conclude that Nmnat2 activity supports axon survival through a site of action distinct from Nmnat2 transport vesicles and that protein stability, a key determinant of axon protection, is enhanced by mutations that disrupt palmitoylation and dissociate Nmnat2 from these vesicles.
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Effects of lithium and valproic acid on gene expression and phenotypic markers in an NT2 neurosphere model of neural development.
PLoS ONE
PUBLISHED: 02-07-2013
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Mood stabilising drugs such as lithium (LiCl) and valproic acid (VPA) are the first line agents for treating conditions such as Bipolar disorder and Epilepsy. However, these drugs have potential developmental effects that are not fully understood. This study explores the use of a simple human neurosphere-based in vitro model to characterise the pharmacological and toxicological effects of LiCl and VPA using gene expression changes linked to phenotypic alterations in cells. Treatment with VPA and LiCl resulted in the differential expression of 331 and 164 genes respectively. In the subset of VPA targeted genes, 114 were downregulated whilst 217 genes were upregulated. In the subset of LiCl targeted genes, 73 were downregulated and 91 were upregulated. Gene ontology (GO) term enrichment analysis was used to highlight the most relevant GO terms associated with a given gene list following toxin exposure. In addition, in order to phenotypically anchor the gene expression data, changes in the heterogeneity of cell subtype populations and cell cycle phase were monitored using flow cytometry. Whilst LiCl exposure did not significantly alter the proportion of cells expressing markers for stem cells/undifferentiated cells (Oct4, SSEA4), neurons (Neurofilament M), astrocytes (GFAP) or cell cycle phase, the drug caused a 1.4-fold increase in total cell number. In contrast, exposure to VPA resulted in significant upregulation of Oct4, SSEA, Neurofilament M and GFAP with significant decreases in both G2/M phase cells and cell number. This neurosphere model might provide the basis of a human-based cellular approach for the regulatory exploration of developmental impact of potential toxic chemicals.
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Functional astrocyte-neuron lactate shuttle in a human stem cell-derived neuronal network.
J. Cereb. Blood Flow Metab.
PUBLISHED: 02-06-2013
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The NT2.D1 cell line is one of the most well-documented embryocarcinoma cell lines, and can be differentiated into neurons and astrocytes. Great focus has also been placed on defining the electrophysiological properties of the neuronal cells, and more recently we have investigated the functional properties of their associated astrocytes. We now show for the first time that human stem cell-derived astrocytes produce glycogen and that co-cultures of these cells demonstrate a functional astrocyte-neuron lactate shuttle (ANLS). The ANLS hypothesis proposes that during neuronal activity, glutamate released into the synaptic cleft is taken up by astrocytes and triggers glucose uptake, which is converted into lactate and released via monocarboxylate transporters for neuronal use. Using mixed cultures of NT2-derived neurons and astrocytes, we have shown that these cells modulate their glucose uptake in response to glutamate. Additionally, we demonstrate that in response to increased neuronal activity and under hypoglycaemic conditions, co-cultures modulate glycogen turnover and increase lactate production. Similar results were also shown after treatment with glutamate, potassium, isoproterenol, and dbcAMP. Together, these results demonstrate for the first time a functional ANLS in a human stem cell-derived co-culture.
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Cytotoxicity of lapachol, ?-lapachone and related synthetic 1,4-naphthoquinones against oesophageal cancer cells.
Eur J Med Chem
PUBLISHED: 01-05-2013
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Naphthoquinones have been found to have a wide range of biological activities, including cytotoxicity to cancer cells. The secondary metabolites lapachol, ?- and ?-lapachone and a series of 25 related synthetic 1,4-naphthoquinones were screened against the oesophageal cancer cell line (WHCO1). Most of the compounds exhibited enhanced cytotoxicity (IC50 1.6-11.7 ?M) compared to the current drug of choice cisplatin (IC50 = 16.5 ?M). This study also established that the two new synthetic halogenated compounds 12a and 16a (IC50 = 3.0 and 7.3 ?M) and the previously reported compound 11a (IC50 = 3.9 ?M), were non-toxic to NIH3T3 normal fibroblast cells. Cell death of oesophageal cancer cells by processes involving PARP cleavage caused by 11a was shown to be associated with elevated c-Jun levels, suggesting a role for this pathway in the mechanism of action of this cohort of naphthoquinone compounds.
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Autophagy in axonal and dendritic degeneration.
Trends Neurosci.
PUBLISHED: 01-03-2013
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Degeneration of axons and dendrites is a common and early pathological feature of many neurodegenerative disorders, and is thought to be regulated by mechanisms distinct from those determining death of the cell body. The unique structures of axons and dendrites (collectively neurites) may cause them to be particularly vulnerable to the accumulation of protein aggregates and damaged organelles. Autophagy is a catabolic mechanism in which cells clear protein aggregates and damaged organelles. Basal autophagy occurs continuously as a housekeeping function, and can be acutely expanded in response to stress or injury. Emerging evidence shows that insufficient or excessive autophagy contributes to neuritic degeneration. Here, we review the recent progress that has begun to reveal the role of autophagy in neurite function and degeneration.
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MEK inhibitor U0126 reverses protection of axons from Wallerian degeneration independently of MEK-ERK signaling.
PLoS ONE
PUBLISHED: 01-01-2013
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Wallerian degeneration is delayed when sufficient levels of proteins with NMNAT activity are maintained within axons after injury. This has been proposed to form the basis of slow Wallerian degeneration (Wld (S)), a neuroprotective phenotype conferred by an aberrant fusion protein, Wld(S). Proteasome inhibition also delays Wallerian degeneration, although much less robustly, with stabilization of NMNAT2 likely to play a key role in this mechanism. The pan-MEK inhibitor U0126 has previously been shown to reverse the axon-protective effects of proteasome inhibition, suggesting that MEK-ERK signaling plays a role in delayed Wallerian degeneration, in addition to its established role in promoting neuronal survival. Here we show that whilst U0126 can also reverse Wld(S)-mediated axon protection, more specific inhibitors of MEK1/2 and MEK5, PD184352 and BIX02189, have no significant effect on the delay to Wallerian degeneration in either situation, whether used alone or in combination. This suggests that an off-target effect of U0126 is responsible for reversion of the axon protective effects of Wld(S) expression or proteasome inhibition, rather than inhibition of MEK1/2-ERK1/2 or MEK5-ERK5 signaling. Importantly, this off-target effect does not appear to result in alterations in the stabilities of either Wld(S) or NMNAT2.
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Methicillin-resistant Staphylococcus aureus (MRSA) pyruvate kinase as a target for bis-indole alkaloids with antibacterial activities.
J. Biol. Chem.
PUBLISHED: 10-26-2011
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Novel classes of antimicrobials are needed to address the emergence of multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA). We have recently identified pyruvate kinase (PK) as a potential novel drug target based upon it being an essential hub in the MRSA interactome (Cherkasov, A., Hsing, M., Zoraghi, R., Foster, L. J., See, R. H., Stoynov, N., Jiang, J., Kaur, S., Lian, T., Jackson, L., Gong, H., Swayze, R., Amandoron, E., Hormozdiari, F., Dao, P., Sahinalp, C., Santos-Filho, O., Axerio-Cilies, P., Byler, K., McMaster, W. R., Brunham, R. C., Finlay, B. B., and Reiner, N. E. (2011) J. Proteome Res. 10, 1139-1150; Zoraghi, R., See, R. H., Axerio-Cilies, P., Kumar, N. S., Gong, H., Moreau, A., Hsing, M., Kaur, S., Swayze, R. D., Worrall, L., Amandoron, E., Lian, T., Jackson, L., Jiang, J., Thorson, L., Labriere, C., Foster, L., Brunham, R. C., McMaster, W. R., Finlay, B. B., Strynadka, N. C., Cherkasov, A., Young, R. N., and Reiner, N. E. (2011) Antimicrob. Agents Chemother. 55, 2042-2053). Screening of an extract library of marine invertebrates against MRSA PK resulted in the identification of bis-indole alkaloids of the spongotine (A), topsentin (B, D), and hamacanthin (C) classes isolated from the Topsentia pachastrelloides as novel bacterial PK inhibitors. These compounds potently and selectively inhibited both MRSA PK enzymatic activity and S. aureus growth in vitro. The most active compounds, cis-3,4-dihyrohyrohamacanthin B (C) and bromodeoxytopsentin (D), were identified as highly potent MRSA PK inhibitors (IC(50) values of 16-60 nM) with at least 166-fold selectivity over human PK isoforms. These novel anti-PK natural compounds exhibited significant antibacterial activities against S. aureus, including MRSA (minimal inhibitory concentrations (MIC) of 12.5 and 6.25 ?g/ml, respectively) with selectivity indices (CC(50)/MIC) >4. We also report the discrete structural features of the MRSA PK tetramer as determined by x-ray crystallography, which is suitable for selective targeting of the bacterial enzyme. The co-crystal structure of compound C with MRSA PK confirms that the latter is a target for bis-indole alkaloids. It elucidates the essential structural requirements for PK inhibitors in "small" interfaces that provide for tetramer rigidity and efficient catalytic activity. Our results identified a series of natural products as novel MRSA PK inhibitors, providing the basis for further development of potential novel antimicrobials.
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Modelling early responses to neurodegenerative mutations in mice.
Biochem. Soc. Trans.
PUBLISHED: 07-27-2011
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Considering the many differences between mice and humans, it is perhaps surprising how well mice model late-onset human neurodegenerative disease. Models of Alzheimers disease, frontotemporal dementia, Parkinsons disease and Huntingtons disease show some striking similarities to the corresponding human pathologies in terms of axonal transport disruption, protein aggregation, synapse loss and some behavioural phenotypes. However, there are also major differences. To extrapolate from mouse models to human disease, we need to understand how these differences relate to intrinsic limitations of the mouse system and to the effects of transgene overexpression. In the present paper, we use examples from an amyloid-overexpression model and a mutant-tau-knockin model to illustrate what we learn from each type of approach and what the limitations are. Finally, we discuss the further contributions that knockin and similar approaches can make to understanding pathogenesis and how best to model disorders of aging in a short-lived mammal.
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Reducing expression of NAD+ synthesizing enzyme NMNAT1 does not affect the rate of Wallerian degeneration.
FEBS J.
PUBLISHED: 06-14-2011
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NAD(+) synthesizing enzyme NMNAT1 constitutes most of the sequence of neuroprotective protein Wld(S), which delays axon degeneration by 10-fold. NMNAT1 activity is necessary but not sufficient for Wld(S) neuroprotection in mice and 70 amino acids at the N-terminus of Wld(S), derived from polyubiquitination factor Ube4b, enhance axon protection by NMNAT1. NMNAT1 activity can confer neuroprotection when redistributed outside the nucleus or when highly overexpressed in vitro and partially in Drosophila. However, the role of endogenous NMNAT1 in normal axon maintenance and in Wallerian degeneration has not been elucidated yet. To address this question we disrupted the Nmnat1 locus by gene targeting. Homozygous Nmnat1 knockout mice do not survive to birth, indicating that extranuclear NMNAT isoforms cannot compensate for its loss. Heterozygous Nmnat1 knockout mice develop normally and do not show spontaneous neurodegeneration or axon pathology. Wallerian degeneration after sciatic nerve lesion is neither accelerated nor delayed in these mice, consistent with the proposal that other endogenous NMNAT isoforms play a principal role in Wallerian degeneration.
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The emergence of insecticide resistance in central Mozambique and potential threat to the successful indoor residual spraying malaria control programme.
Malar. J.
PUBLISHED: 05-02-2011
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Malaria vector control by indoor residual spraying was reinitiated in 2006 with DDT in Zambézia province, Mozambique. In 2007, these efforts were strengthened by the Presidents Malaria Initiative. This manuscript reports on the monitoring and evaluation of this programme as carried out by the Malaria Decision Support Project.
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Insecticide resistance and the future of malaria control in Zambia.
PLoS ONE
PUBLISHED: 04-15-2011
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In line with the Global trend to improve malaria control efforts a major campaign of insecticide treated net distribution was initiated in 1999 and indoor residual spraying with DDT or pyrethroids was reintroduced in 2000 in Zambia. In 2006, these efforts were strengthened by the Presidents Malaria Initiative. This manuscript reports on the monitoring and evaluation of these activities and the potential impact of emerging insecticide resistance on disease transmission.
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The cardioprotective effects of marrubiin, a diterpenoid found in Leonotis leonurus extracts.
J Ethnopharmacol
PUBLISHED: 04-12-2011
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Leonotis leonurus L. (Lamiaceae) is used as a traditional medicine for a variety of ailments in South Africa. The diterpene marrubiin is the major product constituent in specimens of this plant occurring in South Africa.
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Screening for small molecule modulators of Hsp70 chaperone activity using protein aggregation suppression assays: inhibition of the plasmodial chaperone PfHsp70-1.
Biol. Chem.
PUBLISHED: 03-23-2011
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Plasmodium falciparum heat shock protein 70 (PfHsp70-1) is thought to play an essential role in parasite survival and virulence in the human host, making it a potential antimalarial drug target. A malate dehydrogenase based aggregation suppression assay was adapted for the screening of small molecule modulators of Hsp70. A number of small molecules of natural (marine prenylated alkaloids and terrestrial plant naphthoquinones) and related synthetic origin were screened for their effects on the protein aggregation suppression activity of purified recombinant PfHsp70-1. Five compounds (malonganenone A-C, lapachol and bromo-?-lapachona) were found to inhibit the chaperone activity of PfHsp70-1 in a concentration dependent manner, with lapachol preferentially inhibiting PfHsp70-1 compared to another control Hsp70. Using growth inhibition assays on P. falciparum infected erythrocytes, all of the compounds, except for malonganenone B, were found to inhibit parasite growth with IC(50) values in the low micromolar range. Overall, this study has identified two novel classes of small molecule inhibitors of PfHsp70-1, one representing a new class of antiplasmodial compounds (malonganenones). In addition to demonstrating the validity of PfHsp70-1 as a possible drug target, the compounds reported in this study will be potentially useful as molecular probes for fundamental studies on Hsp70 chaperone function.
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Molecular signaling how do axons die?
Adv. Genet.
PUBLISHED: 02-12-2011
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Axons depend critically on axonal transport both for supplying materials and for communicating with cell bodies. This chapter looks at each activity, asking what aspects are essential for axon survival. Axonal transport declines in neurodegenerative disorders, such as Alzheimers disease, amyotrophic lateral sclerosis, and multiple sclerosis, and in normal ageing, but whether all cargoes are equally affected and what limits axon survival remains unclear. Cargoes can be differentially blocked in some disorders, either individually or in groups. Each missing protein cargo results in localized loss-of-function that can be partially modeled by disrupting the corresponding gene, sometimes with surprising results. The axonal response to losing specific proteins also depends on the rates of protein turnover and on whether the protein can be locally synthesized. Among cargoes with important axonal roles are components of the PI3 kinase, Mek/Erk, and Jnk signaling pathways, which help to communicate with cell bodies and to regulate axonal transport itself. Bidirectional trafficking of Bdnf, NT-3, and other neurotrophic factors contribute to intra- and intercellular signaling, affecting the axons cellular environment and survival. Finally, several adhesion molecules and gangliosides are key determinants of axon survival, probably by mediating axon-glia interactions. Thus, failure of long-distance intracellular transport can deprive axons of one, few, or many cargoes. This can lead to axon degeneration either directly, through the absence of essential axonal proteins, or indirectly, through failures in communication with cell bodies and nonneuronal cells.
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Age-dependent axonal transport and locomotor changes and tau hypophosphorylation in a "P301L" tau knockin mouse.
Neurobiol. Aging
PUBLISHED: 02-03-2011
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Tauopathies are characterized by hyperphosphorylation of the microtubule-associated protein tau and its accumulation into fibrillar aggregates. Toxic effects of aggregated tau and/or dysfunction of soluble tau could both contribute to neural defects in these neurodegenerative diseases. We have generated a novel knockin mouse model of an inherited tauopathy, frontotemporal dementia with parkinsonism linked to tau mutations on chromosome 17 (FTDP-17T). We incorporated a single mutation, homologous to the common FTDP-17T P301L mutation, directly into the endogenous mouse gene, mimicking the human disease situation. These mice express P301L-equivalent mutant tau at normal physiological levels from the knockin allele. Importantly, in contrast to existing transgenic mouse models that overexpress human P301L mutant tau, no overt tau pathology developed during the normal lifespan of the knockin mice. In fact, overall phosphorylation of tau was reduced, perhaps due to reduced microtubule binding. However, homozygous knockin mice did display intriguing age-dependent changes in axonal transport of mitochondria, and increased spontaneous locomotor activity in old age. These could represent early consequences of the tau dysfunction that eventually precipitates pathogenesis in humans.
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Multi-disease data management system platform for vector-borne diseases.
PLoS Negl Trop Dis
PUBLISHED: 02-03-2011
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Emerging information technologies present new opportunities to reduce the burden of malaria, dengue and other infectious diseases. For example, use of a data management system software package can help disease control programs to better manage and analyze their data, and thus enhances their ability to carry out continuous surveillance, monitor interventions and evaluate control program performance.
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Human adipose tissue-derived stem cells exhibit proliferation potential and spontaneous rhythmic contraction after fusion with neonatal rat cardiomyocytes.
FASEB J.
PUBLISHED: 11-08-2010
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Various types of stem cells have been shown to have beneficial effects on cardiac function. It is still debated whether fusion of injected stem cells with local resident cardiomyocytes is one of the mechanisms. To better understand the role of fusion in stem cell-based myocardial regeneration, the present study was designed to investigate the fate of human adipose tissue-derived stem cells (hASCs) fused with neonatal rat cardiomyocytes in vitro. hASCs labeled with the green fluorescent probe Vybrant DiO were cocultured with neonatal rat cardiomyocytes labeled with the red fluorescent probe Vybrant DiI and then treated with fusion-inducing hemagglutinating virus of Japan (HVJ). Cells that incorporated both red and green fluorescent signals were considered to be hASCs that had fused with rat cardiomyocytes. Fusion efficiency was 19.86 ± 4.84% at 5 d after treatment with HVJ. Most fused cells displayed cardiomyocyte-like morphology and exhibited spontaneous rhythmic contraction. Both immunofluorescence staining and lentiviral vector labeling showed that fused cells contained separate rat cardiomyocyte and hASC nuclei. Immunofluorescence staining assays demonstrated that human nuclei in fused cells still expressed the proliferation marker Ki67. In addition, hASCs fused with rat cardiomyocytes were positive for troponin I. Whole-cell voltage-clamp analysis demonstrated action potentials in beating fused cells. RT-PCR analysis using rat- or human-specific myosin heavy chain primers revealed that the myosin heavy-chain expression in fused cells was derived from rat cardiomyocytes. Real-time PCR identified expression of human troponin T in fused cells and the presence of rat cardiomyocytes induced a cardiomyogenic protein expression of troponin T in human ASCs. This study illustrates that hASCs exhibit both stem cell (proliferation) and cardiomyocyte properties (action potential and spontaneous rhythmic beating) after fusion with rat cardiomyocytes, supporting the theory that fusion, even if artificially induced in our study, could indeed be a mechanism for cardiomyocyte renewal in the heart.
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Targeting NMNAT1 to axons and synapses transforms its neuroprotective potency in vivo.
J. Neurosci.
PUBLISHED: 10-08-2010
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Axon and synapse degeneration are common components of many neurodegenerative diseases, and their rescue is essential for effective neuroprotection. The chimeric Wallerian degeneration slow protein (Wld(S)) protects axons dose dependently, but its mechanism is still elusive. We recently showed that Wld(S) acts at a non-nuclear location and is present in axons. This and other recent reports support a model in which Wld(S) protects by extranuclear redistribution of its nuclear NMNAT1 portion. However, it remains unclear whether cytoplasmic NMNAT1 acts locally in axons and synapses or at a non-nuclear site within cell bodies. The potency of axon protection by non-nuclear NMNAT1 relative to Wld(S) also needs to be established in vivo. Because the N-terminal portion of Wld(S) (N70) localized to axons, we hypothesized that it mediates the trafficking of the NMNAT1 portion. To test this, we substituted N70 with an axonal targeting peptide derived from amyloid precursor protein, and fused this to NMNAT1 with disrupted nuclear targeting. In transgenic mice, this transformed NMNAT1 from a molecule unable to inhibit Wallerian degeneration, even at high expression levels, into a protein more potent than Wld(S), able to preserve injured axons for several weeks at undetectable expression levels. Preventing NMNAT1 axonal delivery abolished its protective effect. Axonally targeted NMNAT1 localized to vesicular structures, colocalizing with extranuclear Wld(S), and was cotransported at least partially with mitochondria. We conclude that axonal targeting of NMNAT activity is both necessary and sufficient to delay Wallerian degeneration, and that promoting axonal and synaptic delivery greatly enhances the effectiveness.
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Isolation and Characterization of Diastereomers of Discorhabdins H and K and Assignment of Absolute Configuration to Discorhabdins D, N, Q, S, T, and U.
J. Nat. Prod.
PUBLISHED: 09-22-2010
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Investigations of four different sponge populations of Latrunculia species collected in New Zealand waters has led to the characterization of a new diastereomer of discorhabdin H, named discorhabdin H(2), confirmation of the structure of discorhabdin K ((+)-7), and presentation of a new diastereomer, discorhabdin K(2) ((-)-8). In each case the structures were established by extensive NMR and MS studies and the absolute configurations interrogated by electronic circular dichroism (ECD). Absolute configurations were assigned to the known metabolites discorhabdins H, D, 2-hydroxy-D, N, and Q by comparison of ECD spectra with those recorded for discorhabdin alkaloids of defined absolute configuration, while the configurations of discorhabdins S, T, and U were assigned by semisynthesis from (+)-(6S,8S)-discorhabdin B.
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Dapsone hydroxylamine induces premature removal of human erythrocytes by membrane reorganization and antibody binding.
Br. J. Pharmacol.
PUBLISHED: 07-29-2010
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N-hydroxylation of dapsone leads to the formation of the toxic hydroxylamines responsible for the clinical methaemoglobinaemia associated with dapsone therapy. Dapsone has been associated with decreased lifespan of erythrocytes, with consequences such as anaemia and morbidity in patients treated with dapsone for malaria. Here, we investigated how dapsone and/or its hydroxylamine derivative (DDS-NHOH) induced erythrocyte membrane alterations that could lead to premature cell removal.
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The incidence of periodontal defects distal to the maxillary second molar after impacted third molar extraction.
J. Oral Maxillofac. Surg.
PUBLISHED: 07-06-2010
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This study assessed the incidence of periodontal defects on the distal aspect of maxillary second molars after extraction of impacted maxillary third molars.
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Difference Tracker: ImageJ plugins for fully automated analysis of multiple axonal transport parameters.
J. Neurosci. Methods
PUBLISHED: 06-22-2010
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Studies of axonal transport are critical, not only to understand its normal regulation, but also to determine the roles of transport impairment in disease. Exciting new resources have recently become available allowing live imaging of axonal transport in physiologically relevant settings, such as mammalian nerves. Thus the effects of disease, ageing and therapies can now be assessed directly in nervous system tissue. However, these imaging studies present new challenges. Manual or semi-automated analysis of the range of transport parameters required for a suitably complete evaluation is very time-consuming and can be subjective due to the complexity of the particle movements in axons in ex vivo explants or in vivo. We have developed Difference Tracker, a program combining two new plugins for the ImageJ image-analysis freeware, to provide fast, fully automated and objective analysis of a number of relevant measures of trafficking of fluorescently labeled particles so that axonal transport in different situations can be easily compared. We confirm that Difference Tracker can accurately track moving particles in highly simplified, artificial simulations. It can also identify and track multiple motile fluorescently labeled mitochondria simultaneously in time-lapse image stacks from live imaging of tibial nerve axons, reporting values for a number of parameters that are comparable to those obtained through manual analysis of the same axons. Difference Tracker therefore represents a useful free resource for the comparative analysis of axonal transport under different conditions, and could potentially be used and developed further in many other studies requiring quantification of particle movements.
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Thought disorder in offspring of schizophrenic parents: findings from the New York High-Risk Project.
Schizophr Bull
PUBLISHED: 06-16-2010
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The goal of the present analyses was to examine the hypothesis that mild forms of thought disorder (TD) may serve as an indicator of genetic liability for schizophrenia. A subset of 232 subjects drawn from the New York High-Risk Project was used to compare individuals at high risk for schizophrenia (ie, offspring of parents with schizophrenia; n = 63) with 2 groups of individuals at low risk for schizophrenia (ie, offspring of parents with affective disorder [n = 52] and offspring of psychiatrically normal parents [n = 117]). Subjects were administered the Rorschach Inkblot Test, and their responses were assessed according to the Thought Disorder Index (TDI). The high-risk offspring displayed significantly more TD than the other 2 groups, as shown by significantly higher TDI scores. Moreover, they had more deviant verbalizations, according to their significantly higher scores on a composite Idiosyncratic Verbalizations score. As expected, the offspring who developed psychosis produced more TD in adolescence than those who did not develop psychosis. In the sample as a whole, TD scores during late adolescence/early adulthood were positively associated with schizotypal features during mid-adulthood. These findings support the assertion that the presence of TD serves as an endophenotypic marker of a schizophrenia diathesis.
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A low-polynomial algorithm for assembling clusters of orthologous groups from intergenomic symmetric best matches.
Bioinformatics
PUBLISHED: 05-02-2010
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Identifying orthologous genes in multiple genomes is a fundamental task in comparative genomics. Construction of intergenomic symmetrical best matches (SymBets) and joining them into clusters is a popular method of ortholog definition, embodied in several software programs. Despite their wide use, the computational complexity of these programs has not been thoroughly examined.
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Mechanisms of axonal spheroid formation in central nervous system Wallerian degeneration.
J. Neuropathol. Exp. Neurol.
PUBLISHED: 04-27-2010
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Wallerian degeneration of the CNS is accompanied by axonal dystrophy or swelling. To understand the mechanisms by which swellings arise, we studied their spatiotemporal dynamics, ultrastructure, composition, and the conditions that affect their formation in vivo and ex vivo. In contrast to peripheral nerve axons, lesioned optic nerve (ON) axons in vivo developed focal swellings asynchronously within 6 hours, long before there is any axon fragmentation. Axons in ON, spinal cord dorsal column, and corpus callosum all showed marked gradients with more swellings in proximal regions of their distal stumps early after lesion. Time-lapse imaging of a validated ex vivo system showed that multiple focal swellings arise after around 1 hour close to the injury site, followed by anterograde wave-like progression on continuous ON axon stumps. Swellings were largely stable but occasionally seemed to fuse with neighboring swellings. Their ultrastructural appearances resembled disease-associated spheroids. Although accumulation of axonal markers suggested transport deficits, large accumulations of mitochondria were not observed. Early swelling formation was decreased in Wld gene-expressing rodents and by removing extracellular calcium. Several pharmacologic agents that inhibit axon loss in vitro and/or in vivo also prevented early formation of axonal spheroids in acute ON explants. Because axonal swellings are hallmarks of many neurodegenerative conditions, these data suggest that they are a manifestation of Wallerian-like degeneration in some cases. Thus, Wallerian-like degeneration may be a more common component mechanism in CNS diseases than previously thought.
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The Wlds transgene reduces axon loss in a Charcot-Marie-Tooth disease 1A rat model and nicotinamide delays post-traumatic axonal degeneration.
Neurobiol. Dis.
PUBLISHED: 04-08-2010
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Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy and a duplication of the peripheral myelin protein of 22 kDa (PMP22) gene causes the most frequent subform CMT1A. Clinical impairments are determined by the amount of axonal loss. Axons of the spontaneous mouse mutant Wallerian degeneration slow (Wlds) show markedly reduced degeneration following various types of injuries. Protection is conferred by a chimeric Wlds gene encoding an N-terminal part of ubiquitination factor Ube4b and full length nicotinamide mononucleotide adenylyl transferase 1 (Nmnat1). Nmnat1 enzyme generates nicotinamide adenine dinucleotide (NAD) from nicotinamide mononucleotide. Here, in a Pmp22 transgenic animal model of Charcot-Marie-Tooth disease type 1A (CMT rat), the Wlds transgene reduced axonal loss and clinical impairments without altering demyelination. Furthermore, nicotinamide - substrate precursor of the Nmnat1 enzyme - transiently delayed posttraumatic axonal degeneration in an in vivo model of acute peripheral nerve injury, but to a lower extent than Wlds. In contrast, 8 weeks of nicotinamide treatment did not influence axonal loss or clinical manifestations in the CMT rat. Therefore, nicotinamide can partially substitute for the protective Wlds effect in acute traumatic, but not in chronic secondary axonal injury. Future studies are needed to develop axon protective therapy in CMT1A which may be combined with therapeutic strategies aimed at downregulation of toxic PMP22 overexpression.
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Wallerian degeneration, wld(s), and nmnat.
Annu. Rev. Neurosci.
PUBLISHED: 03-30-2010
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Traditionally, researchers have believed that axons are highly dependent on their cell bodies for long-term survival. However, recent studies point to the existence of axon-autonomous mechanism(s) that regulate rapid axon degeneration after axotomy. Here, we review the cellular and molecular events that underlie this process, termed Wallerian degeneration. We describe the biphasic nature of axon degeneration after axotomy and our current understanding of how Wld(S)--an extraordinary protein formed by fusing a Ube4b sequence to Nmnat1--acts to protect severed axons. Interestingly, the neuroprotective effects of Wld(S) span all species tested, which suggests that there is an ancient, Wld(S)-sensitive axon destruction program. Recent studies with Wld(S) also reveal that Wallerian degeneration is genetically related to several dying back axonopathies, thus arguing that Wallerian degeneration can serve as a useful model to understand, and potentially treat, axon degeneration in diverse traumatic or disease contexts.
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The Genetic Basis of Thought Disorder and Language and Communication Disturbances in Schizophrenia.
J Neurolinguistics
PUBLISHED: 02-18-2010
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Thought disorder as well as language and communication disturbances are associated with schizophrenia and are over-represented in clinically unaffected relatives of schizophrenics. All three kinds of dysfunction involve some element of deviant verbalizations, most notably, semantic anomalies. Of particular importance, thought disorder characterized primarily by deviant verbalizations has a higher recurrence in relatives of schizophrenic patients than schizophrenia itself. These findings suggest that deviant verbalizations may be more penetrant expressions of schizophrenia susceptibility genes than schizophrenia. This paper reviews the evidence documenting the presence of thought, language and communication disorders in schizophrenic patients and in their first-degree relatives. This familial aggregation potentially implicates genetic factors in the etiology of thought disorder, language anomalies, and communication disturbances in schizophrenia families. We also present two examples of ways in which thought, language and communication disorders can enrich genetic studies, including those involving schizophrenia.
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Endogenous Nmnat2 is an essential survival factor for maintenance of healthy axons.
PLoS Biol.
PUBLISHED: 01-26-2010
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The molecular triggers for axon degeneration remain unknown. We identify endogenous Nmnat2 as a labile axon survival factor whose constant replenishment by anterograde axonal transport is a limiting factor for axon survival. Specific depletion of Nmnat2 is sufficient to induce Wallerian-like degeneration of uninjured axons which endogenous Nmnat1 and Nmnat3 cannot prevent. Nmnat2 is by far the most labile Nmnat isoform and is depleted in distal stumps of injured neurites before Wallerian degeneration begins. Nmnat2 turnover is equally rapid in injured Wld(S) neurites, despite delayed neurite degeneration, showing it is not a consequence of degeneration and also that Wld(S) does not stabilize Nmnat2. Depletion of Nmnat2 below a threshold level is necessary for axon degeneration since exogenous Nmnat2 can protect injured neurites when expressed at high enough levels to overcome its short half-life. Furthermore, proteasome inhibition slows both Nmnat2 turnover and neurite degeneration. We conclude that endogenous Nmnat2 prevents spontaneous degeneration of healthy axons and propose that, when present, the more long-lived, functionally related Wld(S) protein substitutes for Nmnat2 loss after axon injury. Endogenous Nmnat2 represents an exciting new therapeutic target for axonal disorders.
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Schizophrenia patients show deficits in shifts of attention to different levels of global-local stimuli: evidence for magnocellular dysfunction.
Schizophr Bull
PUBLISHED: 09-08-2009
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Abnormalities of attention and visual perception are well documented in schizophrenia. The global-local task is a measure of attention and perceptual organization that utilizes visual stimuli comprised of large letters (global level) made up of smaller letters (local level). Subjects identify target letters appearing at either the global or local level of the stimulus. In this study, we used a version of the global-local task specifically designed to examine lateralized hemispheric processing and attention shifting in 30 schizophrenia patients and 24 normal controls. Global-local stimuli were presented in couplets (consecutive pairs). Reaction time for the second target in a couplet was compared under conditions in which the target remained at the same level (global-global, local-local) and when the target changed levels (global-local, local-global). Level-specific priming (ie, global to global and local to local) and the local-to-global level shift were similar in both groups. Schizophrenia patients were significantly slower, however, shifting attention from the global to the local level. These results implicate an impairment in shifting attentional resources from predominantly right lateralized magnocellular/dorsal stream processing of global targets to predominantly left lateralized parvocellular/ventral stream processing of local targets. Local interference effects in global processing provide further support for impaired magnocellular processing in schizophrenia patients.
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Combining indoor residual spraying and insecticide-treated net interventions.
Am. J. Trop. Med. Hyg.
PUBLISHED: 08-27-2009
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Does scaling up of malaria control by combining indoor residual spraying (IRS) and long-lasting insecticidal nets (LLIN) enhance protection to populations? Results from a literature search and from recent household surveys in Bioko, Equatorial Guinea, and Zambezia, Mozambique are presented. Five out of eight previous studies reported a reduced risk of infection in those protected by both interventions compared with one intervention alone. Surveys in Bioko and Zambezia showed strong evidence of a protective effect of IRS combined with nets relative to IRS alone (odds ratio [OR] = 0.71, 95% confidence interval [CI] = 0.59-0.86 for Bioko, and OR = 0.63, 95% CI = 0.50-0.79, for Zambezia). The effect of both interventions combined, compared with those who had neither, was OR = 0.46, (95% CI = 0.76-0.81) in Bioko and 0.34 (95% CI = 0.21-0.56) in Zambezia. Although the effects of confounding cannot be excluded, these results provide encouragement that the additional resources for combining IRS and LLIN are justified.
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Tailoring the definition of the clinical schizophrenia phenotype in linkage studies.
Schizophr. Res.
PUBLISHED: 07-08-2009
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The delineation of schizophrenia-related symptomatology is critical to informative clinical phenotyping in linkage studies. A minority of first-degree relatives of schizophrenia and schizoaffective probands (RelSZSA) qualifies for a clinical diagnosis in the schizophrenia spectrum. Schizotypal personality disorder (SPD) is a key component of this spectrum, largely because of its relatively specific familial aggregation in relatives. The criteria for SPD were not developed for the purpose of identifying RelSZSA, however, and SPD is not a homogeneous clinical disorder, potentially introducing false positives and false negatives into affectedness classifications. In this study we used logistic regression (LR) to identify the combination of clinical signs and symptoms that maximized the discrimination between nonpsychotic first-degree RelSZSA (n=241) and controls (n=161). Three variables contributed significantly to optimizing this distinction: no close friends or confidants other than family members, social isolation and irritability. The combination of deviant LR scores and schizophrenia-spectrum psychotic disorders had greater sensitivity for identifying RelSZSA, 23.7%, than SPD and schizophrenia-spectrum psychotic disorders, 16%. Importantly, the diagnosis of SPD and deviant LR scores were not significantly correlated. Most individuals with deviant LR scores did not meet criteria for a diagnosis of SPD and only a minority of those who were diagnosed with SPD had deviant LR scores. Since misclassification of gene carriers as non-gene carriers in linkage analyses increases the risk of false negatives, it may be advantageous to tailor the definition of the clinical phenotype to those aspects of social-interpersonal dysfunction that optimize the discrimination of RelSZSA from controls.
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Cardiogenic arterial thromboembolism causing non-ambulatory tetraparesis in a cat.
J. Feline Med. Surg.
PUBLISHED: 06-23-2009
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A 1-year-old oriental cat was presented with a peracute onset of tetraparesis and vocalisation. Clinical findings were suggestive of multi-site thromboembolic disease, and this was confirmed on post-mortem examination. An echocardiogram showed severe restrictive cardiomyopathy and spontaneous echogenic contrast. To the authors knowledge, this is the first reported case of tetraparesis secondary to cardiogenic arterial thromboembolic disease. Thromboembolic disease should be included as a differential diagnosis for any cat presented with a peracute onset of paresis or paralysis, even if there is no history of cardiac disease.
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Reinforcement ambiguity and novelty do not account for transitive inference deficits in schizophrenia.
Schizophr Bull
PUBLISHED: 05-21-2009
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The capacity for transitive inference (TI), a form of relational memory organization, is impaired in schizophrenia patients. In order to disambiguate deficits in TI from the effects of ambiguous reinforcement history and novelty, 28 schizophrenia and 20 nonpsychiatric control subjects were tested on newly developed TI and non-TI tasks that were matched on these 2 variables. Schizophrenia patients performed significantly worse than controls on the TI task but were able to make equivalently difficult nontransitive judgments as well as controls. Neither novelty nor reinforcement ambiguity accounted for the selective deficit of the patients on the TI task. These findings implicate a disturbance in relational memory organization, likely subserved by hippocampal dysfunction, in the pathophysiology of schizophrenia.
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Axonal and neuromuscular synaptic phenotypes in Wld(S), SOD1(G93A) and ostes mutant mice identified by fiber-optic confocal microendoscopy.
Mol. Cell. Neurosci.
PUBLISHED: 05-07-2009
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We used live imaging by fiber-optic confocal microendoscopy (CME) of yellow fluorescent protein (YFP) expression in motor neurons to observe and monitor axonal and neuromuscular synaptic phenotypes in mutant mice. First, we visualized slow degeneration of axons and motor nerve terminals at neuromuscular junctions following sciatic nerve injury in Wld(S) mice with slow Wallerian degeneration. Protection of axotomized motor nerve terminals was much weaker in Wld(S) heterozygotes than in homozygotes. We then induced covert modifiers of axonal and synaptic degeneration in heterozygous Wld(S) mice, by N-ethyl-N-nitrosourea (ENU) mutagenesis, and used CME to identify candidate mutants that either enhanced or suppressed axonal or synaptic degeneration. From 219 of the F1 progeny of ENU-mutagenized BALB/c mice and thy1.2-YFP16/Wld(S) mice, CME revealed six phenodeviants with suppression of synaptic degeneration. Inheritance of synaptic protection was confirmed in three of these founders, with evidence of Mendelian inheritance of a dominant mutation in one of them (designated CEMOP_S5). We next applied CME repeatedly to living Wld(S) mice and to SOD1(G93A) mice, an animal model of motor neuron disease, and observed degeneration of identified neuromuscular synapses over a 1-4day period in both of these mutant lines. Finally, we used CME to observe slow axonal regeneration in the ENU-mutant ostes mouse strain. The data show that CME can be used to monitor covert axonal and neuromuscular synaptic pathology and, when combined with mutagenesis, to identify genetic modifiers of its progression in vivo.
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Using the SaTScan method to detect local malaria clusters for guiding malaria control programmes.
Malar. J.
PUBLISHED: 04-17-2009
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Mpumalanga Province, South Africa is a low malaria transmission area that is subject to malaria epidemics. SaTScan methodology was used by the malaria control programme to detect local malaria clusters to assist disease control planning. The third season for case cluster identification overlapped with the first season of implementing an outbreak identification and response system in the area.
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Severely dystrophic axons at amyloid plaques remain continuous and connected to viable cell bodies.
Brain
PUBLISHED: 03-11-2009
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Synapse loss precedes cell death in Alzheimers disease, but the timing of axon degeneration relative to these events, and the causal relationships remain unclear. Axons become so severely dystrophic near amyloid plaques that their interruption, causing permanent loss of function, extensive synapse loss, and potentially cell death appears imminent. However, it remains unclear whether axons are truly interrupted at plaques and whether cell bodies fail to support their axons and dendrites. We traced TgCRND8 mouse axons longitudinally through, distal to, and proximal from dystrophic regions. The corresponding neurons not only survived but remained morphologically unaltered, indicating absence of axonal damage signalling or a failure to respond to it. Axons, no matter how dystrophic, remained continuous and initially morphologically normal outside the plaque region, reflecting support by metabolically active cell bodies and continued axonal transport. Immunochemical and ultrastructural studies showed dystrophic axons were tightly associated with disruption of presynaptic transmission machinery, suggesting local functional impairment. Thus, we rule out long-range degeneration axons or dendrites as major contributors to early synapse loss in this model, raising the prospect of a therapeutic window for functional rescue of individual neurons lasting months or even years after their axons become highly dystrophic. We propose that multi-focal pathology has an important role in the human disease in bringing about the switch from local, and potentially recoverable, synapse loss into permanent loss of neuronal processes and eventually their cell bodies.
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Wld S protein requires Nmnat activity and a short N-terminal sequence to protect axons in mice.
J. Cell Biol.
PUBLISHED: 02-25-2009
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The slow Wallerian degeneration (Wld(S)) protein protects injured axons from degeneration. This unusual chimeric protein fuses a 70-amino acid N-terminal sequence from the Ube4b multiubiquitination factor with the nicotinamide adenine dinucleotide-synthesizing enzyme nicotinamide mononucleotide adenylyl transferase 1. The requirement for these components and the mechanism of Wld(S)-mediated neuroprotection remain highly controversial. The Ube4b domain is necessary for the protective phenotype in mice, but precisely which sequence is essential and why are unclear. Binding to the AAA adenosine triphosphatase valosin-containing protein (VCP)/p97 is the only known biochemical property of the Ube4b domain. Using an in vivo approach, we show that removing the VCP-binding sequence abolishes axon protection. Replacing the Wld(S) VCP-binding domain with an alternative ataxin-3-derived VCP-binding sequence restores its protective function. Enzyme-dead Wld(S) is unable to delay Wallerian degeneration in mice. Thus, neither domain is effective without the function of the other. Wld(S) requires both of its components to protect axons from degeneration.
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Late onset distal axonal swelling in YFP-H transgenic mice.
Neurobiol. Aging
PUBLISHED: 02-20-2009
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Axonal swellings, or spheroids, are a feature of central nervous system (CNS) axon degeneration during normal aging and in many disorders. The direct cause and mechanism are unknown. The use of transgenic mouse line YFP-H, which expresses yellow-fluorescent protein (YFP) in a subset of neurons, greatly facilitates longitudinal imaging and live imaging of axonal swellings, but it has not been established whether long-term expression of YFP itself contributes to axonal swelling. Using conventional methods to compare YFP-H mice with their YFP negative littermates, we found an age-related increase in swellings in discrete CNS regions in both genotypes, but the presence of YFP caused significantly more swellings in mice aged 8 months or over. Increased swelling was found in gracile tract, gracile nucleus and dorsal roots but not in lateral columns, olfactory bulb, motor cortex, ventral roots or peripheral nerve. Thus, long-term expression of YFP accelerates age-related axonal swelling in some axons and data reliant on the presence of YFP in these CNS regions in older animals needs to be interpreted carefully. The ability of a foreign protein to exacerbate age-related axon pathology is an important clue to the mechanisms by which such pathology can arise.
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Household and microeconomic factors associated with malaria in Mpumalanga, South Africa.
Trans. R. Soc. Trop. Med. Hyg.
PUBLISHED: 02-15-2009
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A household matched case-control study design was used to explore associations between household characteristics and malaria risk in seven study towns in the hypoendemic area of Mpumalanga Province, South Africa. Controls were identified from neighboring households of each case. Principle component analysis was used to calculate a wealth index for households to allow comparison across socioeconomic groups. Conditional univariate and multiple logistic regression analyses were used to assess associations between household malaria risk and potential risk factors. Univariate analysis demonstrated an increased household malaria risk for people living in mud-walled houses compared with those in brick dwellings (OR=5.10, 95% CI 2.03-12.80, P=0.001). Multivariate analysis confirmed the association between malaria risk and mud-wall construction (OR=6.12, 95% CI 2.26-16.59, P=0.001) and demonstrated an association with opening windows after retiring to sleep (OR=4.01, 95% CI 1.32-12.18, P=0.014). An inverse association between household wealth, third (OR=0.24, 95% CI 0.09-0.65, P=0.005) and fourth quartiles (OR=0.27, 95% CI 0.10-0.79, P=0.016), and malaria risk was observed. Associations found here include increased household malaria risk and mud-wall construction, the practice of opening of windows at night and relative household poverty. Education campaigns targeting risk behavior may reduce malaria risk, but economic development is a more important intervention.
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Effect of freshly isolated autologous tissue resident stromal cells on cardiac function and perfusion following acute myocardial infarction.
Int. J. Cardiol.
PUBLISHED: 02-11-2009
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The aim of this study was to investigate the effect of intracoronary administration of freshly isolated, uncultured autologous tissue-derived stromal cells on cardiac function and perfusion after acute infarction in pigs.
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Detection of biochemical pathways by probabilistic matching of phyletic vectors.
PLoS ONE
PUBLISHED: 02-10-2009
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A phyletic vector, also known as a phyletic (or phylogenetic) pattern, is a binary representation of the presences and absences of orthologous genes in different genomes. Joint occurrence of two or more genes in many genomes results in closely similar binary vectors representing these genes, and this similarity between gene vectors may be used as a measure of functional association between genes. Better understanding of quantitative properties of gene co-occurrences is needed for systematic studies of gene function and evolution. We used the probabilistic iterative algorithm Psi-square to find groups of similar phyletic vectors. An extended Psi-square algorithm, in which pseudocounts are implemented, shows better sensitivity in identifying proteins with known functional links than our earlier hierarchical clustering approach. At the same time, the specificity of inferring functional associations between genes in prokaryotic genomes is strongly dependent on the pathway: phyletic vectors of the genes involved in energy metabolism and in de novo biosynthesis of the essential precursors tend to be lumped together, whereas cellular modules involved in secretion, motility, assembly of cell surfaces, biosynthesis of some coenzymes, and utilization of secondary carbon sources tend to be identified with much greater specificity. It appears that the network of gene coinheritance in prokaryotes contains a giant connected component that encompasses most biosynthetic subsystems, along with a series of more independent modules involved in cell interaction with the environment.
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Tau inclusions in retinal ganglion cells of human P301S tau transgenic mice: effects on axonal viability.
Neurobiol. Aging
PUBLISHED: 02-09-2009
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Tau inclusions play a key role in the pathogenesis of tauopathies. Altered tau levels have been detected in retina and optic nerve of patients with glaucoma, suggesting the possibility of shared pathogenic mechanisms with tauopathies. Here we report that hyperphosphorylated transgenic tau accumulates in the nerve fibre layer and, from 2 months of age, aggregates into filamentous inclusions in retinal ganglion cells of human P301S tau transgenic mice. Axonopathy and accumulation of hyperphosphorylated tau in the nerve fibre layer preceded inclusion formation. Hyperphosphorylated tau and tau inclusions were also detected in cultured retinal explants from 5-month-old transgenic mice. Axonal outgrowth was similar in transgenic and wild-type retinal explants under basal conditions. However, when exposed to growth-promoting stimuli, axon elongation was enhanced in explants from wild-type but not transgenic mice, indicating that the presence of abnormal tau can impair stimulated axonal outgrowth. These findings suggest that the retina is a good model system for investigating tau-driven neurodegeneration and for assessing potential pharmacological modifiers for tauopathies.
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Evolutionary divergence of valosin-containing protein/cell division cycle protein 48 binding interactions among endoplasmic reticulum-associated degradation proteins.
FEBS J.
PUBLISHED: 01-30-2009
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Endoplasmic reticulum (ER)-associated degradation (ERAD) is a cell-autonomous process that eliminates large quantities of misfolded, newly synthesized protein, and is thus essential for the survival of any basic eukaryotic cell. Accordingly, the proteins involved and their interaction partners are well conserved from yeast to mammals, and Saccharomyces cerevisiae is widely used as a model system with which to investigate this fundamental cellular process. For example, valosin-containing protein (VCP) and its yeast homologue cell division cycle protein 48 (Cdc48p), which help to direct polyubiquitinated proteins for proteasome-mediated degradation, interact with an equivalent group of ubiquitin ligases in mouse and in S. cerevisiae. A conserved structural motif for cofactor binding would therefore be expected. We report a VCP-binding motif (VBM) shared by mammalian ubiquitin ligase E4b (Ube4b)-ubiquitin fusion degradation protein 2a (Ufd2a), hydroxymethylglutaryl reductase degradation protein 1 (Hrd1)-synoviolin and ataxin 3, and a related sequence in M(r) 78,000 glycoprotein-Amfr with slightly different binding properties, and show that Ube4b and Hrd1 compete for binding to the N-terminal domain of VCP. Each of these proteins is involved in ERAD, but none has an S. cerevisiae homologue containing the VBM. Some other invertebrate model organisms also lack the VBM in one or more of these proteins, in contrast to vertebrates, where the VBM is widely conserved. Thus, consistent with their importance in ERAD, evolution has developed at least two ways to bring these proteins together with VCP-Cdc48p. However, the differing molecular architecture of VCP-Cdc48p complexes indicates a key point of divergence in the molecular details of ERAD mechanisms.
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Non-nuclear Wld(S) determines its neuroprotective efficacy for axons and synapses in vivo.
J. Neurosci.
PUBLISHED: 01-23-2009
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Axon degeneration contributes widely to neurodegenerative disease but its regulation is poorly understood. The Wallerian degeneration slow (Wld(S)) protein protects axons dose-dependently in many circumstances but is paradoxically abundant in nuclei. To test the hypothesis that Wld(S) acts within nuclei in vivo, we redistributed it from nucleus to cytoplasm in transgenic mice. Surprisingly, instead of weakening the phenotype as expected, extranuclear Wld(S) significantly enhanced structural and functional preservation of transected distal axons and their synapses. In contrast to native Wld(S) mutants, distal axon stumps remained continuous and ultrastructurally intact up to 7 weeks after injury and motor nerve terminals were robustly preserved even in older mice, remaining functional for 6 d. Moreover, we detect extranuclear Wld(S) for the first time in vivo, and higher axoplasmic levels in transgenic mice with Wld(S) redistribution. Cytoplasmic Wld(S) fractionated predominantly with mitochondria and microsomes. We conclude that Wld(S) can act in one or more non-nuclear compartments to protect axons and synapses, and that molecular changes can enhance its therapeutic potential.
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Simultaneous single-sample determination of NMNAT isozyme activities in mouse tissues.
PLoS ONE
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A novel assay procedure has been developed to allow simultaneous activity discrimination in crude tissue extracts of the three known mammalian nicotinamide mononucleotide adenylyltransferase (NMNAT, EC 2.7.7.1) isozymes. These enzymes catalyse the same key reaction for NAD biosynthesis in different cellular compartments. The present method has been optimized for NMNAT isozymes derived from Mus musculus, a species often used as a model for NAD-biosynthesis-related physiology and disorders, such as peripheral neuropathies. Suitable assay conditions were initially assessed by exploiting the metal-ion dependence of each isozyme recombinantly expressed in bacteria, and further tested after mixing them in vitro. The variable contributions of the three individual isozymes to total NAD synthesis in the complex mixture was calculated by measuring reaction rates under three selected assay conditions, generating three linear simultaneous equations that can be solved by a substitution matrix calculation. Final assay validation was achieved in a tissue extract by comparing the activity and expression levels of individual isozymes, considering their distinctive catalytic efficiencies. Furthermore, considering the key role played by NMNAT activity in preserving axon integrity and physiological function, this assay procedure was applied to both liver and brain extracts from wild-type and Wallerian degeneration slow (Wld(S)) mouse. Wld(S) is a spontaneous mutation causing overexpression of NMNAT1 as a fusion protein, which protects injured axons through a gain-of-function. The results validate our method as a reliable determination of the contributions of the three isozymes to cellular NAD synthesis in different organelles and tissues, and in mutant animals such as Wld(S).
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Impact assessment of malaria vector control using routine surveillance data in Zambia: implications for monitoring and evaluation.
Malar. J.
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Malaria vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), with pyrethroids and DDT, to reduce malaria transmission has been expansively implemented in Zambia. The impact of these interventions on malaria morbidity and mortality has not previously been formally assessed at the population level in Zambia.
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Impact of pyrethroid resistance on operational malaria control in Malawi.
Proc. Natl. Acad. Sci. U.S.A.
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The impact of insecticide resistance on insect-borne disease programs is difficult to quantify. The possibility of eliminating malaria in high-transmission settings is heavily dependent on effective vector control reducing disease transmission rates. Pyrethroids are the dominant insecticides used for malaria control, with few options for their replacement. Their failure will adversely affect our ability to control malaria. Pyrethroid resistance has been selected in Malawi over the last 3 y in the two major malaria vectors Anopheles gambiae and Anopheles funestus, with a higher frequency of resistance in the latter. The resistance in An. funestus is metabolically based and involves the up-regulation of two duplicated P450s. The same genes confer resistance in Mozambican An. funestus, although the levels of up-regulation differ. The selection of resistance over 3 y has not increased malaria transmission, as judged by annual point prevalence surveys in 1- to 4-y-old children. This is true in areas with long-lasting insecticide-treated nets (LLINs) alone or LLINs plus pyrethroid-based insecticide residual spraying (IRS). However, in districts where IRS was scaled up, it did not produce the expected decrease in malaria prevalence. As resistance increases in frequency from this low initial level, there is the potential for vector population numbers to increase with a concomitant negative impact on control efficacy. This should be monitored carefully as part of the operational activities in country.
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Axon pathology in age-related neurodegenerative disorders.
Neuropathol. Appl. Neurobiol.
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Dying back axon degeneration is a prominent feature of many age-related neurodegenerative disorders and is widespread in normal ageing. Although the mechanisms of disease- and age-related losses may differ, both contribute to symptoms. Here, we review recent advances in understanding axon pathology in age-related neurodegenerative disorders such as Alzheimers disease, Parkinsons disease, amyotrophic lateral sclerosis and glaucoma. In particular, we highlight the importance of axonal transport, autophagy, traumatic brain injury, and mitochondrial quality control. We then place these disease mechanisms in the context of changes to axons and dendrites that occur during normal ageing. We discuss what makes ageing such an important risk factor for many neurodegenerative disorders and conclude that the processes of normal ageing and disease combine at the molecular, cellular or systems levels in a range of disorders to produce symptoms. Pathology identical to disease also occurs at the cellular level in most elderly individuals. Thus, normal ageing and age-related disease are inextricably linked and the term healthy ageing downplays the important contributions of cellular pathology. For a full understanding of normal ageing or age-related disease we must study both processes.
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Antimicrobial rubrolides from a South African species of Synoicum tunicate.
J. Nat. Prod.
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The CH?Cl?-MeOH extract of a South African tunicate described as the new Synoicum globosum Parker-Nance sp. nov. (Ascidiacea, Aplousobranchia) was subjected to ¹H NMR-guided fractionation. This resulted in the identification of new 3?-bromorubrolide F (1), 3-bromorubrolide E (2), 3-bromorubrolide F (3), and 3,3?-dibromorubrolide E (4) and reisolation of known rubrolides E (5) and F (6), based on NMR spectroscopic and mass spectrometric data. Biological testing of both new and known members of this reported antimicrobial family of halogenated, aryl-substituted furanones indicated moderate antibacterial properties for 3-bromorubrolide E (2), 3,3?-dibromorubrolide E (4), and rubrolide F (6) against methicillin-resistant Staphylococcus aureus (MRSA) and S. epidermidis.
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Patterns of deficits in brain function in bipolar disorder and schizophrenia: a cluster analytic study.
Psychiatry Res
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Historically, bipolar disorder and schizophrenia have been considered distinct disorders with different etiologies. Growing evidence suggests that overlapping genetic influences contribute to risk for these disorders and that each disease is genetically heterogeneous. Using cluster analytic methods, we empirically identified homogeneous subgroups of patients, their relatives, and controls based on distinct neurophysiologic profiles. Seven phenotypes were collected from two independent cohorts at two institutions. K-means clustering was used to identify neurophysiologic profiles. In the analysis of all participants, three distinct profiles emerged: "globally impaired", "sensory processing", and "high cognitive". In a secondary analysis, restricted to patients only, we observed a similar clustering into three profiles. The neurophysiological profiles of the Schizophrenia (SZ) and Bipolar Disorder (BPD) patients did not support the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic distinction between these two disorders. Smokers in the globally impaired group smoked significantly more cigarettes than those in the sensory processing or high cognitive groups. Our results suggest that empirical analyses of neurophysiological phenotypes can identify potentially biologically relevant homogenous subgroups independent of diagnostic boundaries. We hypothesize that each neurophysiology subgroup may share similar genotypic profiles, which may increase statistical power to detect genetic risk factors.
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Highly selective synthesis of tetra-substituted furans and cyclopropenes: copper(I)-catalyzed formal cycloadditions of internal aryl alkynes and diazoacetates.
Org. Biomol. Chem.
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A convenient Cu(I)-catalyzed cycloaddition of electron rich internal aryl alkynes and diazoacetates was discovered for the chemoselective and regioselective synthesis of tetra-substituted furans and cyclopropenes in moderate isolated yields (18-67%), and alkyne conversion (29-73%).
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A preliminary investigation into the impact of a pesticide combination on human neuronal and glial cell lines in vitro.
PLoS ONE
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Many pesticides are used increasingly in combinations during crop protection and their stability ensures the presence of such combinations in foodstuffs. The effects of three fungicides, pyrimethanil, cyprodinil and fludioxonil, were investigated together and separately on U251 and SH-SY5Y cells, which can be representative of human CNS glial and neuronal cells respectively. Over 48h, all three agents showed significant reductions in cellular ATP, at concentrations that were more than tenfold lower than those which significantly impaired cellular viability. The effects on energy metabolism were reflected in their marked toxic effects on mitochondrial membrane potential. In addition, evidence of oxidative stress was seen in terms of a fall in cellular thiols coupled with increases in the expression of enzymes associated with reactive species formation, such as GSH peroxidase and superoxide dismutase. The glial cell line showed significant responsiveness to the toxin challenge in terms of changes in antioxidant gene expression, although the neuronal SH-SY5Y line exhibited greater vulnerability to toxicity, which was reflected in significant increases in caspase-3 expression, which is indicative of the initiation of apoptosis. Cyprodinil was the most toxic agent individually, although oxidative stress-related enzyme gene expression increases appeared to demonstrate some degree of synergy in the presence of the combination of agents. This report suggests that the impact of some pesticides, both individually and in combinations, merits further study in terms of their impact on human cellular health.
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Comparison of putative intermediate phenotypes in schizophrenia patients with and without obsessive-compulsive disorder: examining evidence for the schizo-obsessive subtype.
Schizophr. Res.
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Obsessive-compulsive symptoms or obsessive-compulsive disorder (OCD) is estimated to occur in up to 30% of patients with schizophrenia. Whether this subgroup of patients is cognitively, affectively, or physiologically distinct remains unclear. 204 schizophrenia patients, 15 who also met criteria for a diagnosis of OCD, and 147 healthy controls were examined on several intermediate phenotypes. The patient groups did not differ from each other except that the co-morbid group exhibited an elevated rate of eye-tracking dysfunction. Results suggest that OCD-co-morbid patients did not comprise a distinct subgroup based on the measures studied here, although systematic assessment of larger cohorts is warranted.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.