221 research outputs found
Influence of cardiac autonomic neuropathy on cardiac repolarisation during incremental adrenaline infusion in type 1 diabetes
Aims/hypothesis
We examined the effect of a standardised sympathetic stimulus, incremental adrenaline (epinephrine) infusion on cardiac repolarisation in individuals with type 1 diabetes with normal autonomic function, subclinical autonomic neuropathy and established autonomic neuropathy.
Methods
Ten individuals with normal autonomic function and baroreceptor sensitivity tests (NAF), seven with subclinical autonomic neuropathy (SAN; normal standard autonomic function tests and abnormal baroreceptor sensitivity tests); and five with established cardiac autonomic neuropathy (CAN; abnormal standard autonomic function and baroreceptor tests) underwent an incremental adrenaline infusion. Saline (0.9% NaCl) was infused for the first hour followed by 0.01 μg kg−1 min−1 and 0.03 μg kg−1 min−1 adrenaline for the second and third hours, respectively, and 0.06 μg kg−1 min−1 for the final 30 min. High resolution ECG monitoring for QTc duration, ventricular repolarisation parameters (T wave amplitude, T wave area symmetry ratio) and blood sampling for potassium and catecholamines was performed every 30 min.
Results
Baseline heart rate was 68 (95% CI 60, 76) bpm for the NAF group, 73 (59, 87) bpm for the SAN group and 84 (78, 91) bpm for the CAN group. During adrenaline infusion the heart rate increased differently across the groups (p = 0.01). The maximum increase from baseline (95% CI) in the CAN group was 22 (13, 32) bpm compared with 11 (7, 15) bpm in the NAF and 10 (3, 18) bpm in the SAN groups. Baseline QTc was 382 (95% CI 374, 390) ms in the NAF, 378 (363, 393) ms in the SAN and 392 (367, 417) ms in the CAN groups (p = 0.31). QTc in all groups lengthened comparably with adrenaline infusion. The longest QTc was 444 (422, 463) ms (NAF), 422 (402, 437) ms (SAN) and 470 (402, 519) ms (CAN) (p = 0.09). T wave amplitude and T wave symmetry ratio decreased and the maximum decrease occurred earlier, at lower infused adrenaline concentrations in the CAN group compared with NAF and SAN groups. AUC for the symmetry ratio was different across the groups and was lowest in the CAN group (p = 0.04). Plasma adrenaline rose and potassium fell comparably in all groups.
Conclusions/interpretation
Participants with CAN showed abnormal repolarisation in some measures at lower adrenaline concentrations. This may be due to denervation adrenergic hypersensitivity. Such individuals may be at greater risk of cardiac arrhythmias in response to physiological sympathoadrenal challenges such as stress or hypoglycaemia
Ab initio molecular dynamics simulations of Aluminum solvation
The solvation of Al and its hydrolyzed species in water clusters has been
studied by means of ab initio molecular dynamics simulations. The hexa-hydrate
aluminum ion formed a stable complex in the finite temperature cluster
simulation of one aluminum ion and 16 waters. The average dipole moment of
strongly polarized hydrated water molecules in the first solvation shell of the
hexa-hydrate aluminum ion was found to be 5.02 Debye. The deprotonated
hexa-hydrate complex evolves into a tetra-coordinated aluminate ion with two
water molecules in the second solvation shell forming hydrogen bonds to the
hydroxyl groups in agreement with the observed coordination.Comment: 12 pages in Elsevier LaTeX, 5 figures in Postscript, 2 last figures
are in color, submitted to Chemical Physics Letter
Nucleon-nucleon momentum correlation function for light nuclei
Nucleon-nucleon momentum correlation function have been presented for nuclear
reactions with neutron-rich or proton-rich projectiles using a nuclear
transport theory, namely Isospin-Dependent Quantum Molecular Dynamics model.
The relationship between the binding energy of projectiles and the strength of
proton-neutron correlation function at small relative momentum has been
explored, while proton-proton correlation function shows its sensitivity to the
proton density distribution. Those results show that nucleon-nucleon
correlation function is useful to reflect some features of the neutron- or
proton-halo nuclei and therefore provide a potential tool for the studies of
radioactive beam physics.Comment: Talk given at the 18th International IUPAP Conference on Few-Body
Problems in Physics (FB18), Santos, Brasil, August 21-26, 2006. To appear in
Nucl. Phys.
Mid-to-Late Holocene environmental reconstruction on Pico Island (Azores, Portugal) based on multiproxy analysis of Lake Caveiro sediments
The Azores constitutes the most remote archipelago of the North Atlantic Ocean. Both human
colonization and natural changes have significantly modified its ecosystems. To assess the
impacts of natural and anthropogenic changes over the last 8200 yr, elemental geochemistry on
bulk organic matter, diatoms, Cladocera and chironomid remains were analyzed in a 952-cm long
sediment (3.7m depth) from Lake Caveiro.
From 8200 to 650 cal yr BP, climatic and volcanic forcing seem to have been the main drivers of
biological change. Between 8200 and 6000 cal yr BP, the sedimentary sequence was
characterized by dominance of volcaniclastic deposits and high abundance of aerophilic diatoms
and sparse Cladocera and chironomid remains. This interval has been interpreted as indicative of
unstable conditions because of intermittent renewal of lake bottom substratum owing to repetitive
tephra sedimentation. Between 6000 and 3500 cal yr BP, fossil assemblages were dominated by
benthic species, with an increasing trend of the planktonic/benthic (P:B) ratio, suggesting stable
substratum and rising lake levels. An increase in planktonic taxa and the presence of deep-water
chironomid species was found between 3500 and 1300 cal yr BP, suggesting a highstand phase.
Between 1300 and 650 cal yr BP, a decreasing trend of the P:B ratio was recorded, implying a
further lake shallowing. Moreover, the appearance of flowing water species suggests a period
characterized by climate instability. From 650 cal yr BP to the present, a significant increase in
primary production and a decline in species richness likely reflect anthropogenic impacts, such as
forest clearance and the introduction of exotic species. These results highlight the impact that
human, volcanic and climatic drivers have had on the environmental evolution of the ecosystems
of Pico Island.This research is funded by Spanish projects PaleoNAO (CGL2010-15767), RapidNAO (CGL2013-40608-R) and PaleoModes (CGL2016-75281-C2).Peer Reviewe
Relativistic K shell decay rates and fluorescence yields for Zn, Cd and Hg
In this work we use the multiconfiguration Dirac-Fock method to calculate the
transition probabilities for all possible decay channels, radiative and
radiationless, of a K shell vacancy in Zn, Cd and Hg atoms. The obtained
transition probabilities are then used to calculate the corresponding
fluorescence yields which are compared to existing theoretical, semi-empirical
and experimental results
Chemical Proteomic Analysis of Serine Hydrolase Activity in Niemann-Pick Type C Mouse Brain
The endocannabinoid system (ECS) is considered to be an endogenous protective system in various neurodegenerative diseases. Niemann-Pick type C (NPC) is a neurodegenerative disease in which the role of the ECS has not been studied yet. Most of the endocannabinoid enzymes are serine hydrolases, which can be studied using activity-based protein profiling (ABPP). Here, we report the serine hydrolase activity in brain proteomes of a NPC mouse model as measured by ABPP. Two ABPP methods are used: a gel-based method and a chemical proteomics method. The activities of the following endocannabinoid enzymes were quantified: diacylglycerol lipase (DAGL) α, α/β-hydrolase domain-containing protein 4, α/β-hydrolase domain-containing protein 6, α/β-hydrolase domain-containing protein 12, fatty acid amide hydrolase, and monoacylglycerol lipase. Using the gel-based method, two bands were observed for DAGL α. Only the upper band corresponding to this enzyme was significantly decreased in the NPC mouse model. Chemical proteomics showed that three lysosomal serine hydrolase activities (retinoid-inducible serine carboxypeptidase, cathepsin A, and palmitoyl-protein thioesterase 1) were increased in Niemann-Pick C1 protein knockout mouse brain compared to wild-type brain, whereas no difference in endocannabinoid hydrolase activity was observed. We conclude that these targets might be interesting therapeutic targets for future validation studies.Medical BiochemistryBio-organic SynthesisMolecular Physiolog
Biology and fertility life table of Mahanarva fimbriolata (Stål) (Hemiptera: Cercopidae) in sugarcane
Mahanarva fimbriolata (StÃ¥l) (Hemiptera: Cercopidae) is the most important pest of sugarcane harvested without the use of fire to burn leaf trash. Its biology was studied for three generations in order to obtain basic information about its life cycle. A fertility life table was used to evaluate the quality of laboratory-reared insects. Data were obtained at a temperature of 25 ± 1ºC, RH of 70 ± 10%, and a 14-hour photophase. The incubation period lasted 21 days with a viability of 81%; the nymph stage had a duration of 37 days, with a 94% viability; the male and female longevities were 18 and 23 days, respectively, with a pre-oviposition period of 5 days and an oviposition period of 16 days, with a fecundity of 342 eggs, with a life-cycle (egg-adult) of 60 days. A net reproductive rate (Ro) of 131 females produced per female per generation was measured, with a finite rate of increase (lambda) of 1.085. The fertility life table proved to be adequate to be evaluate the quality of laboratory-reared M. fimbriolata populations.A cigarrinha-das-raÃzes, Mahanarva fimbriolata (StÃ¥l) (Hemiptera: Cercopidae), é considerada a principal praga da cana-de-açúcar colhida sem despalha a fogo no Brasil. Neste trabalho, estudou-se sua biologia por três gerações, visando obter informações básicas sobre seu ciclo de vida. Para avaliar a qualidade dos insetos criados em laboratório utilizou-se a tabela de vida de fertilidade. Os dados foram obtidos sob temperatura de 25 ± 1ºC, UR de 70 ± 10% e fotofase de 14 horas. O perÃodo de incubação foi de 21 dias e a viabilidade de 81%; a duração da fase ninfal foi de 37 dias, com viabilidade de 94%; as longevidades de machos e de fêmeas foram de 18 e 23 dias respectivamente, com perÃodo de pré-oviposição de 5 dias e oviposição de 16 dias, com fecundidade de 342 ovos, com duração do ciclo de vida (ovo-adulto) de 60 dias. A taxa lÃquida de reprodução (Ro) foi de 131 fêmeas geradas por fêmea por geração e a taxa finita de aumento (lambda) de 1,085. A tabela de vida de fertilidade mostrou-se adequada para avaliar a qualidade de populações de M. fimbriolata mantidas em criação de laboratório
Machine Learning Framework to Identify Individuals at Risk of Rapid Progression of Coronary Atherosclerosis : From the PARADIGM Registry
Background Rapid coronary plaque progression (RPP) is associated with incident cardiovascular events. To date, no method exists for the identification of individuals at risk of RPP at a single point in time. This study integrated coronary computed tomography angiography-determined qualitative and quantitative plaque features within a machine learning (ML) framework to determine its performance for predicting RPP. Methods and Results Qualitative and quantitative coronary computed tomography angiography plaque characterization was performed in 1083 patients who underwent serial coronary computed tomography angiography from the PARADIGM (Progression of Atherosclerotic Plaque Determined by Computed Tomographic Angiography Imaging) registry. RPP was defined as an annual progression of percentage atheroma volume 651.0%. We employed the following ML models: model 1, clinical variables; model 2, model 1 plus qualitative plaque features; model 3, model 2 plus quantitative plaque features. ML models were compared with the atherosclerotic cardiovascular disease risk score, Duke coronary artery disease score, and a logistic regression statistical model. 224 patients (21%) were identified as RPP. Feature selection in ML identifies that quantitative computed tomography variables were higher-ranking features, followed by qualitative computed tomography variables and clinical/laboratory variables. ML model 3 exhibited the highest discriminatory performance to identify individuals who would experience RPP when compared with atherosclerotic cardiovascular disease risk score, the other ML models, and the statistical model (area under the receiver operating characteristic curve in ML model 3, 0.83 [95% CI 0.78-0.89], versus atherosclerotic cardiovascular disease risk score, 0.60 [0.52-0.67]; Duke coronary artery disease score, 0.74 [0.68-0.79]; ML model 1, 0.62 [0.55-0.69]; ML model 2, 0.73 [0.67-0.80]; all P<0.001; statistical model, 0.81 [0.75-0.87], P=0.128). Conclusions Based on a ML framework, quantitative atherosclerosis characterization has been shown to be the most important feature when compared with clinical, laboratory, and qualitative measures in identifying patients at risk of RPP
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