1,667 research outputs found
A gas-to-particle conversion mechanism helps to explain atmospheric particle formation through clustering of iodine oxides
Get PDFEmitted from the oceans, iodine-bearing molecules are ubiquitous in the atmosphere and a source of new atmospheric aerosol particles of potentially global significance. However, its inclusion in atmospheric models is hindered by a lack of understanding of the first steps of the photochemical gas-to-particle conversion mechanism. Our laboratory results show that under a high humidity and low HOx regime, the recently proposed nucleating molecule (iodic acid, HOIO2) does not form rapidly enough, and gas-to-particle conversion proceeds by clustering of iodine oxides (IxOy), albeit at slower rates than under dryer conditions. Moreover, we show experimentally that gas-phase HOIO2 is not necessary for the formation of HOIO2-containing particles. These insights help to explain new particle formation in the relatively dry polar regions and, more generally, provide for the first time a thermochemically feasible molecular mechanism from ocean iodine emissions to atmospheric particles that is currently missing in model calculations of aerosol radiative forcing
Multivariate Base Rates of Low Score on Neuropsychological Tests of Individuals with Coca Paste Use Disorder
Get PDFObjective
The aim of this study was to determine the prevalence of low scores on eight commonly used neuropsychological tests to evaluate learning and memory, language, and executive functions in individuals with coca paste use disorders (CPUD) and to identify the differences with respect to a group of healthy nonconsuming subjects (HCs).
Methods
162 Colombian adults with CPUD and a group of 162 Colombian adult HCs participated in this comparative study. Eight tests (eighteen test scores) were grouped into three categories: learning and memory, language, and executive functions. Each participant was categorized based on the number of low scoring tests in specific percentile cut-off groups (25th, 16th, 10th, 5th, and 2nd).
Results
In the learning and memory domain, 89.5% of individuals with CPUD and 55.6% of HCs scored below the 25th percentile on at least one of the five test scores, in the language domain, 80.7% of individuals with CPUD and 58% of HCs and in the executive function domain, 92% of individuals with CPUD and 67.3% of HCs. Having two or more scores below the 10th percentile or 10 or more at the 5th percentile shows an optimal cut-off for determining the sensitivity and specificity for discriminating between the two groups.
Conclusions
The individuals with CPUD had a higher percentage of low scores than the HCs in the domains of learning and memory, language, and executive function. It is important for clinicians to be aware of low scores in individuals with CPUD to avoid false-positive diagnoses of cognitive impairment
The first steps of iodine gas-to-particle conversion as seen in the lab: constraints on the role of iodine oxides and oxyacids
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<p>The photooxidation of gas phase iodine-bearing molecules emitted by marine biota leads to intense particle nucleation events in the coastal and polar marine boundary layer<sup>1-3</sup>. The ubiquity of iodine in the marine atmospheric environment<sup>4-7</sup> has suggested that this may be a previously unrecognized global source of new aerosol particles<sup>8</sup>. Atmospheric modeling is required in order to evaluate the importance of this process, but a substantial lack of understanding of the gas-to-particle conversion mechanism is hindering this effort, especially regarding the gas phase chemistry of the nucleating molecules (iodine oxides<sup>9</sup><sup>,</sup><sup>10</sup> and/or oxyacids<sup>7</sup>) and the formation kinetics of molecular clusters. To address this problem, we have conducted new flow tube laboratory experiments where pulsed laser photolysis or continuous broad-band photolysis of I<sub>2</sub>/O<sub>3</sub> mixtures  in air are used to generate iodine radicals in the presence of atmospherically representative mixing ratios of water vapor. The molecular reactants and the resulting molecular products are detected by time-resolved VUV laser photo-ionization time-of-flight mass spectrometry. High-level quantum chemistry and master equation calculations and gas kinetics modelling are used to analyse the experimental data. In this presentation we discuss our results and their implications for the interpretation of field meassurements and for the implementatiion of an iodine oxide particle formation mechanism in atmospheric models.</p><p>References:</p><p>1. Hoffmann, T., O'Dowd, C. D. & Seinfeld, J. H. Iodine oxide homogeneous nucleation: An explanation for coastal new particle production. Geophys. Res. Lett. <strong>28</strong>, 1949-1952 (2001).</p><p>2. McFiggans, G. et al. Direct evidence for coastal iodine particles from Laminaria macroalgae - linkage to emissions of molecular iodine. Atmos. Chem. Phys. <strong>4</strong>, 701-713 (2004).</p><p>3. O'Dowd, C. D. et al. Marine aerosol formation from biogenic iodine emissions. Nature <strong>417</strong>, 632-636 (2002).</p><p>4. Prados-Roman, C. et al. Iodine oxide in the global marine boundary layer. Atmos. Chem. Phys. <strong>15</strong>, 583-593, doi:10.5194/acp-15-583-2015 (2015).</p><p>5. Schönhardt, A. et al. Simultaneous satellite observations of IO and BrO over Antarctica. Atmos. Chem. Phys. <strong>12</strong>, 6565-6580, doi:10.5194/acp-12-6565-2012 (2012).</p><p>6. Mahajan, A. S. et al. Concurrent observations of atomic iodine, molecular iodine and ultrafine particles in a coastal environment. Atmos. Chem. Phys. <strong>10</strong>, 27227-27253 (2010).</p><p>7. Sipilä, M. et al. Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3. Nature <strong>537</strong>, 532-534, doi:10.1038/nature19314 (2016).</p><p>8. Saiz-Lopez, A. et al. Atmospheric Chemistry of Iodine. Chem. Rev. <strong>112</strong>, 1773–1804, doi:DOI: 10.1021/cr200029u (2012).</p><p>9. Gómez Martín, J. C. et al. On the mechanism of iodine oxide particle formation. Phys. Chem. Chem. Phys. <strong>15</strong>, 15612-15622, doi:10.1039/c3cp51217g (2013).</p><p>10. Saunders, R. W., Mahajan, A. S., Gómez Martín, J. C., Kumar, R. & Plane, J. M. C. Studies of the Formation and Growth of Aerosol from Molecular Iodine Precursor. Z. Phys. Chem. <strong>224</strong>, 1095-1117 (2010).</p>
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Litio como terapia neuroprotectora en el modelo appsl/ps1m146l de la enfermedad de Alzheimer
Get PDFEl litio se utiliza desde hace varias décadas en el tratamiento de trastornos bipolares y la depresión, y recientemente se debate su uso potencial en patologías neurodegenerativas como la enfermedad de Alzheimer (AD)
Factitious disorder mimicking addiction to levodopa in a patient with advanced Parkinson's disease
Full text linkThe influence of semantic and phonological factors on syntactic decisions: An event-related brain potential study
Get PDFDuring language production and comprehension, information about a word's syntactic properties is sometimes needed. While the decision about the grammatical gender of a word requires access to syntactic knowledge, it has also been hypothesized that semantic (i.e., biological gender) or phonological information (i.e., sound regularities) may influence this decision. Event-related potentials (ERPs) were measured while native speakers of German processed written words that were or were not semantically and/or phonologically marked for gender. Behavioral and ERP results showed that participants were faster in making a gender decision when words were semantically and/or phonologically gender marked than when this was not the case, although the phonological effects were less clear. In conclusion, our data provide evidence that even though participants performed a grammatical gender decision, this task can be influenced by semantic and phonological factors
Aotus infulatus monkey is susceptible to Plasmodium falciparum infection and may constitute an alternative experimental model for malaria
Full text linkChronic Neuropsychological Sequelae of Cholinesterase Inhibitors in the Absence of Structural Brain Damage: Two Cases of Acute Poisoning
Get PDFHere we describe two cases of carbamate poisoning. Patients AMF and PVM were accidentally poisoned by cholinesterase inhibitors. The medical diagnosis in both cases was overcholinergic syndrome, as demonstrated by exposure to cholinesterase inhibitors. The widespread use of cholinesterase inhibitors, especially as pesticides, produces a great number of human poisoning events annually. The main known neurotoxic effect of these substances is cholinesterase inhibition, which causes cholinergic overstimulation. Once AMF and PVM had recovered from acute intoxication, they were subjected to extensive neuropsychological evaluation 3 and 12 months after the poisoning event. These assessments point to a cognitive deficit in attention, memory, perceptual, and motor domains 3 months after intoxication. One year later these sequelae remained, even though the brain magnetic resonance imaging (MRI) and computed tomography (CT) scans were interpreted as being within normal limits. We present these cases as examples of neuropsychological profiles of long-term sequelae related to acute poisoning by cholinesterase inhibitor pesticides and show the usefulness of neuropsychological assessment in detecting central nervous system dysfunction in the absence of biochemical or structural markers
Two highly divergent alcohol dehydrogenases of melon exhibit fruit ripening-specific expression and distinct biochemical characteristics
Get PDFAlcohol dehydrogenases (ADH) participate in
the biosynthetic pathway of aroma volatiles in fruit by
interconverting aldehydes to alcohols and providing substrates
for the formation of esters. Two highly divergent
ADH genes (15% identity at the amino acid level) of
Cantaloupe Charentais melon (Cucumis melo var. Cantalupensis)
have been isolated. Cm-ADH1 belongs to the
medium-chain zinc-binding type of ADHs and is highly
similar to all ADH genes expressed in fruit isolated so far.
Cm-ADH2 belongs to the short-chain type of ADHs. The
two encoded proteins are enzymatically active upon
expression in yeast. Cm-ADH1 has strong preference for
NAPDH as a co-factor, whereas Cm-ADH2 preferentially
uses NADH. Both Cm-ADH proteins are much more active
as reductases with Kms 10–20 times lower for the conversion
of aldehydes to alcohols than for the dehydrogenation
of alcohols to aldehydes. They both show strong preference
for aliphatic aldehydes but Cm-ADH1 is capable of
reducing branched aldehydes such as 3-methylbutyraldehyde,
whereas Cm-ADH2 cannot. Both Cm-ADH genes are
expressed specifically in fruit and up-regulated during
ripening. Gene expression as well as total ADH activity are
strongly inhibited in antisense ACC oxidase melons and in
melon fruit treated with the ethylene antagonist 1-methylcyclopropene
(1-MCP), indicating a positive regulation by
ethylene. These data suggest that each of the Cm-ADH
protein plays a specific role in the regulation of aroma
biosynthesis in melon fruit
Longitudinal grey and white matter changes in frontotemporal dementia and Alzheimer's disease
Get PDFBehavioural variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD) dementia are characterised by progressive brain atrophy. Longitudinal MRI volumetry may help to characterise ongoing structural degeneration and support the differential diagnosis of dementia subtypes. Automated, observer-independent atlas-based MRI volumetry was applied to analyse 102 MRI data sets from 15 bvFTD, 14 AD, and 10 healthy elderly control participants with consecutive scans over at least 12 months. Anatomically defined targets were chosen a priori as brain structures of interest. Groups were compared regarding volumes at clinic presentation and annual change rates. Baseline volumes, especially of grey matter compartments, were significantly reduced in bvFTD and AD patients. Grey matter volumes of the caudate and the gyrus rectus were significantly smaller in bvFTD than AD. The bvFTD group could be separated from AD on the basis of caudate volume with high accuracy (79% cases correct). Annual volume decline was markedly larger in bvFTD and AD than controls, predominantly in white matter of temporal structures. Decline in grey matter volume of the lateral orbitofrontal gyrus separated bvFTD from AD and controls. Automated longitudinal MRI volumetry discriminates bvFTD from AD. In particular, greater reduction of orbitofrontal grey matter and temporal white matter structures after 12 months is indicative of bvFTD
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