169 research outputs found
The electronic structure of the aqueous permanganate ion: aqueous-phase energetics and molecular bonding studied using liquid jet photoelectron spectroscopy
Permanganate aqueous solutions, MnO4(aq.)-, were studied using liquid-micro-jet-based soft X-ray non-resonant and resonant photoelectron spectroscopy to determine valence and core-level binding energies. To identify possible differences in the energetics between the aqueous bulk and the solution-gas interface, non-resonant spectra were recorded at two different probing depths. Similar experiments were performed with different counter ions, Na(+)and K+, with the two solutions yielding indistinguishable anion electron binding energies. Our resonant photoelectron spectroscopy measurements, performed near the Mn L-II,L-III- and O K-edges, selectively probed valence charge distributions between the Mn metal center, O ligands, and first solvation shell in the aqueous bulk. Associated resonantly-enhanced solute ionisation signals revealed hybridisation of the solute constituents' atomic orbitals, including the inner valence Mn 3p and O 2s. We identified intermolecular coulombic decay relaxation processes following resonant X-ray excitation of the solute that highlight valence MnO4(aq.)--H(2)O((l))electronic couplings. Furthermore, our results allowed us to infer oxidative reorganisation energies of MnO(4)((aq.))and adiabatic valence ionisation energies of MnO4(aq.)-, revealing the Gibbs free energy of oxidation and permitting estimation of the vertical electron affinity of MnO4(aq.). Finally, the Gibbs free energy of hydration of isolated MnO(4)(-)was determined. Our results and analysis allowed a near-complete binding-energy-scaled MnO(4)((aq.))(-)molecular orbital and a valence energy level diagram to be produced for the MnO4(aq.)-/MnO(4)((aq.))system. Cumulatively, our mapping of the aqueous-phase electronic structure of MnO(4)(-)is expected to contribute to a deeper understanding of the exceptional redox properties of this widely applied aqueous transition-metal complex ion
Microvascular Perfusion Abnormalities of the Thalamus in Painful but Not Painless Diabetic Polyneuropathy: A clue to the pathogenesis of pain in type 1 diabetes
OBJECTIVE The pathogenesis of painful diabetic neuropathy (DN) remains undetermined, with both central and peripheral mechanisms implicated. This study investigates whether thalamic perfusion abnormalities occur in painful DN.
RESEARCH DESIGN AND METHODS Eighteen subjects with type 1 diabetes (no DN = 6, painful DN = 5, painless DN = 7) and six healthy volunteers (HV) were recruited. Microvascular perfusion characteristics (relative cerebral blood volume [rCBV], flow [rCBF], and transit time [ttFM]) of the thalamus and caudate nucleus were assessed using magnetic resonance perfusion imaging. The caudate nucleus was chosen to serve as an in vivo control region.
RESULTS Subjects with painful DN had significantly greater thalamic rCBV (means [SD]; painful DN, 228.7 [19.5]; no DN, 202.3 [25.8]; painless DN, 216.5 [65.5]; HV, 181.9 [51.7]; P = 0.04) and the longest ttFM(s) (painful DN, 38.4 [3.6]; no DN, 35.3 [13.2]; painless DN, 35.9 [13.7]; HV, 33.7 [14.9]; P = 0.07). There was no significant difference in markers of caudate nucleus perfusion.
CONCLUSIONS Painful DN is associated with increased thalamic vascularity. This may provide an important clue to the pathogenesis of pain in DN
A Neuroanatomical Basis for the Frequency of Discrete Spontaneous Activities in Schizophrenia
Limited behavioural repertoire impacts quality of life in chronic schizophrenia. We have previously shown that the amount of movement exhibited by patients with schizophrenia is positively correlated with the volume of left anterior cingulate cortex and that this quantity of movement can be increased by modafinil. However, increased movement in itself may be of limited clinical significance. Hence, we sought to analyse the ‘structure’ of spontaneous movement in patients with schizophrenia and to examine whether the chunking of spontaneous activity has a neuroanatomical basis. ‘Actiwatches’ were used to record spontaneous motor activity over a 20 hour period in sixteen male patients with schizophrenia. Time-series data were analysed for the number of discrete spontaneous activities, which might indicate a degree of structure to ongoing activity. Subjects underwent a whole-brain structural MRI scan. The ‘number of discrete movement epochs’ correlated with volumes of regions within bilateral rostro-ventral putamen and temporal poles. These data suggest that in people with schizophrenia the volume of bilateral putamen may influence the complexity of their behaviours, as distinct from the overall amount of behaviour. The results are presented in the context of a large body of previous research examining the role of the basal ganglia in motor and cognitive pattern generation
The neural correlates of emotion regulation by implementation intentions
Several studies have investigated the neural basis of effortful emotion regulation (ER) but the neural basis of automatic ER has been less comprehensively explored. The present study investigated the neural basis of automatic ER supported by ‘implementation intentions’. 40 healthy participants underwent fMRI while viewing emotion-eliciting images and used either a previously-taught effortful ER strategy, in the form of a goal intention (e.g., try to take a detached perspective), or a more automatic ER strategy, in the form of an implementation intention (e.g., “If I see something disgusting, then I will think these are just pixels on the screen!”), to regulate their emotional response. Whereas goal intention ER strategies were associated with activation of brain areas previously reported to be involved in effortful ER (including dorsolateral prefrontal cortex), ER strategies based on an implementation intention strategy were associated with activation of right inferior frontal gyrus and ventro-parietal cortex, which may reflect the attentional control processes automatically captured by the cue for action contained within the implementation intention. Goal intentions were also associated with less effective modulation of left amygdala, supporting the increased efficacy of ER under implementation intention instructions, which showed coupling of orbitofrontal cortex and amygdala. The findings support previous behavioural studies in suggesting that forming an implementation intention enables people to enact goal-directed responses with less effort and more efficiency
The neural correlates of regulating another person's emotions: an exploratory fMRI study
Studies investigating the neurophysiological basis of intrapersonal emotion regulation (control of one's own emotional experience) report that the frontal cortex exerts a modulatory effect on limbic structures such as the amygdala and insula. However, no imaging study to date has examined the neurophysiological processes involved in interpersonal emotion regulation, where the goal is explicitly to regulate another person's emotion. Twenty healthy participants (10 males) underwent fMRI while regulating their own or another person's emotions. Intrapersonal and interpersonal emotion regulation tasks recruited an overlapping network of brain regions including bilateral lateral frontal cortex, pre-supplementary motor area, and left temporo-parietal junction. Activations unique to the interpersonal condition suggest that both affective (emotional simulation) and cognitive (mentalizing) aspects of empathy may be involved in the process of interpersonal emotion regulation. These findings provide an initial insight into the neural correlates of regulating another person's emotions and may be relevant to understanding mental health issues that involve problems with social interaction
Preservation of thalamic neuronal function may be a prerequisite for pain perception in diabetic neuropathy: A magnetic resonance spectroscopy study
IntroductionIn this study, we used proton Magnetic Resonance Spectroscopy (1H-MRS) to determine the neuronal function in the thalamus and primary somatosensory (S1) cortex in different subgroups of DPN, including subclinical- and painful-DPN.MethodOne-hundred and ten people with type 1 diabetes [20 without DPN (no-DPN); 30 with subclinical-DPN; 30 with painful-DPN; and 30 with painless-DPN] and 20 healthy volunteers, all of whom were right-handed men, were recruited and underwent detailed clinical and neurophysiological assessments. Participants underwent Magnetic Resonance Imaging at 1.5 Tesla with two 1H-MRS spectra obtained from 8 ml cubic volume voxels: one placed within left thalamus to encompass the ventro-posterior lateral sub-nucleus and another within the S1 cortex.ResultsIn the thalamus, participants with painless-DPN had a significantly lower NAA:Cr ratio [1.55 + 0.22 (mean ± SD)] compared to all other groups [HV (1.80 ± 0.23), no-DPN (1.85 ± 0.20), sub-clinical DPN (1.79 ± 0.23), painful-DPN (1.75 ± 0.19), ANOVA p < 0.001]. There were no significant group differences in S1 cortical neurometabolites.ConclusionIn this largest cerebral MRS study in DPN, thalamic neuronal dysfunction was found in advanced painless-DPN with preservation of function in subclinical- and painful-DPN. Furthermore, there was a preservation of neuronal function within the S1 cortex in all subgroups of DPN. Therefore, there may be a proximo-distal gradient to central nervous system alterations in painless-DPN, with thalamic neuronal dysfunction occurring only in established DPN. Moreover, these results further highlight the manifestation of cerebral alterations between painful- and painless-DPN whereby preservation of thalamic function may be a prerequisite for neuropathic pain in DPN
Loss of ELK1 has differential effects on age-dependent organ fibrosis and integrin expression
ETS domain-containing protein-1 (ELK1) is a transcription factor important in regulating αvβ6 integrin expression. αvβ6 integrins activate the profibrotic cytokine Transforming Growth Factor β1 (TGFβ1) and are increased in the alveolar epithelium in idiopathic pulmonary fibrosis (IPF). IPF is a disease associated with aging and therefore we hypothesised that aged animals lacking Elk1 globally would develop spontaneous fibrosis in organs where αvβ6 mediated TGFβ activation has been implicated. Here we identify that Elk1-knockout (Elk1−/0) mice aged to one year developed spontaneous fibrosis in the absence of injury in both the lung and the liver but not in the heart or kidneys. The lungs of Elk1−/0 aged mice demonstrated increased collagen deposition, in particular collagen 3α1, located in small fibrotic foci and thickened alveolar walls. Despite the liver having relatively low global levels of ELK1 expression, Elk1−/0 animals developed hepatosteatosis and fibrosis. The loss of Elk1 also had differential effects on Itgb1, Itgb5 and Itgb6 expression in the four organs potentially explaining the phenotypic differences in these organs. To understand the potential causes of reduced ELK1 in human disease we exposed human lung epithelial cells and murine lung slices to cigarette smoke extract, which lead to reduced ELK1 expression andmay explain the loss of ELK1 in human disease. These data support a fundamental role for ELK1 in protecting against the development of progressive fibrosis via transcriptional regulation of beta integrin subunit genes, and demonstrate that loss of ELK1 can be caused by cigarette smoke
Numerical Study of Magnetoaerodynamic Flow Around a Hemisphere
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/83560/1/AIAA-49278-455.pd
Alcohol Induces Sensitization to Gluten in Genetically Susceptible Individuals: A Case Control Study
Background: The mechanisms of cerebellar degeneration attributed to prolonged and excessive alcohol intake remain unclear. Additional or even alternative causes of cerebellar degeneration are often overlooked in suspected cases of alcohol-related ataxia. The objectives of this study were two fold: (1) to investigate the prevalence of gluten-related serological markers in patients with alcohol-related ataxia and; (2) to compare the pattern of brain involvement on magnetic resonance imaging between patients with alcohol and gluten ataxias.
Materials & Methods: Patients diagnosed with alcohol and gluten ataxias were identified from a retrospective review of patients attending a tertiary clinic. HLA genotype and serological markers of gluten-related disorders were recorded. Cerebellar volumetry, MR spectroscopy and voxel-based morphometric analyses were performed on patients and compared with matched control data.
Results: Of 904 registered patients, 104 had alcohol ataxia and 159 had gluten ataxia. 61% of the alcohol ataxia group and 70% of the gluten ataxia group had HLA DQ2/DQ8 genotype compared to 30% in healthy local blood donors. 44% of patients with alcohol ataxia had antigliadin antibodies compared to 12% in the healthy local population and 10% in patients with genetically confirmed ataxias. None of the patients with alcohol ataxia and antigliadin antibodies had celiac disease compared to 40% in patients with gluten ataxia. The pattern of structural brain abnormality in patients with alcohol ataxia who had antigliadin antibodies differed from gluten ataxia and was identical to that of alcohol ataxia.
Conclusions: Alcohol related cerebellar degeneration may, in genetically susceptible individuals, induce sensitization to gluten. Such sensitization may result from a primary cerebellar insult, but a more systemic effect is also possible. The duration and amount of exposure to alcohol may not be the only factors responsible for the cerebellar insult
Investigation and management of young-onset hypertension: British and Irish Hypertension Society position statement
National and international hypertension guidelines recommend that adults with young-onset hypertension (aged <40 years at diagnosis) are reviewed by a hypertension specialist to exclude secondary causes of hypertension and optimise therapeutic regimens. A recent survey among UK secondary care hypertension specialist physicians highlighted variations in the investigation of such patients. In this position statement, the British and Irish Hypertension Society seek to provide clinicians with a practical approach to the investigation and management of adults with young-onset hypertension. We aim to ensure that individuals receive consistent and high-quality care across the UK and Ireland, to highlight gaps in the current evidence, and to identify important future research questions
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