Abstract Previous studies have suggested beneficial effects of physical activity on cognition. Here, we asked in an interventional approach if physical activity performed at different intensity ...levels would differentially affect episodic memory function. Additionally, we tried to identify mechanisms mediating these changes. Sixty-two healthy elderly individuals were assessed for level of physical activity, aerobic fitness, episodic memory score, neurotrophin and catecholamine levels, and received a magnetic resonance image of the brain at baseline and after a six months intervention of medium or low-intensity physical activity or control. Increase in total physical activity was positively associated with increase in memory score over the entire cohort, without significant differences between intensity groups. It was also positively associated with increases in local gray matter volume in prefrontal and cingulate cortex, and BDNF levels (trend). In conclusion, we showed that physical activity conveys the beneficial effects on memory function independently of its intensity, possibly mediated by local gray matter volume and neurotrophic factors. Our findings may carry significant implications for prevention of cognitive decline in the elderly.
To investigate the association between diabetes and impaired fasting glucose (IFG) and cognition and risk of developing both dementia and mild cognitive impairment (MCI) in older women.
The authors ...analyzed data from a 4-year randomized trial of raloxifene among 7,027 osteoporotic postmenopausal women (mean age, 66.3 years) at 178 sites. Diabetes was defined by history, fasting blood glucose > or =7.0 mmol/L (> or =126 mg/dL), or use of hypoglycemic agents; IFG was defined as fasting glucose <7.0 mmol/L but >6.11 mmol/L (110 mg/dL); all others were considered to have normal glucose (NG). The main outcome was baseline and 4-year change on five standardized cognitive tests (z scores with lower scores indicating worse performance) and risk of developing clinically significant impairment (dementia, mild cognitive impairment, or very low cognitive score).
A total of 267 (3.8%) women had diabetes and 297 (4.2%) had IFG. Women with IFG had worse baseline cognitive scores compared to women with NG but better scores than diabetics (age-adjusted composite z score based on five tests: NG 0.40, 95% CI 0.30 to 0.49; IFG 0.14, 95% CI -0.36 to 0.64; diabetics -0.78, 95% CI -1.23 to -0.33; p < 0.001). There was greater 4-year decline among diabetics (age and treatment-adjusted composite z score: NG -0.05, 95% CI -0.16 to 0.05; IFG 0.11, 95% CI -0.53 to 0.75; diabetics -1.00, 95% CI -1.50 to -0.50; p = 0.001). Further adjustment for education, race, and depression led to similar results. Risk of developing cognitive impairment among women with IFG or diabetes was increased by almost twofold (age and treatment-adjusted OR = 1.64; 95% CI 1.03 to 2.61 for IFG; OR = 1.79; 95% CI 1.14 to 2.81 for diabetics).
Diabetic as well as pre-diabetic women have impaired cognitive performance and greater risk of developing cognitive impairment.
Human fetal exposure to valproic acid (VPA), a widely-used anti-epileptic and mood-stabilizing drug, leads to an increased incidence of behavioral and intellectual impairments including autism; VPA ...administration to pregnant rats and mice at gestational days 12.5 (E12.5) or E13.5 leads to autistic-like symptoms in the offspring and is widely used as an animal model for autism. We report here that this VPA administration protocol transiently increased both BDNF mRNA and BDNF protein levels 5–6-fold in the fetal mouse brain. VPA exposure in utero induced smaller increases in the expression of mRNA encoding the other neurotrophins, NT3 (2.5-fold) and NT4 (2-fold). Expression of the neurotrophin receptors, trkA, trkB and trkC were minimally affected, while levels of the low-affinity neurotrophin receptor, p75NTR, doubled. Of the nine 5′-untranslated exons of the mouse BDNF gene, only expression of exons I, IV and VI was stimulated by VPA in utero. In light of the well-established role of BDNF in regulating neurogenesis and the laminar fate of postmitotic neurons in the developing cortex, an aberrant increase in BDNF expression in the fetal brain may contribute to VPA-induced cognitive disorders by altering brain development.
A toy model of the post-shock region of core-collapse supernovae is used to study the non-linear development of turbulent motions driven by convection in the presence of advection. Our numerical ...simulations indicate that buoyant perturbations of density are able to trigger self-sustained convection only when the instability is not linearly stabilized by advection. Large amplitude perturbations produced by strong shock oscillations or combustion inhomogeneities before the collapse of the progenitor are efficiently shredded through phase mixing and generate a turbulent cascade. Our model enables us to investigate several physical arguments that had been proposed to explain the impact of the dimensionality on the onset of explosions in global simulations of core-collapse supernovae. Three-dimensional (3D) simulations are found to lead to higher entropy values than two-dimensional (2D) ones. We attribute this to greater turbulent mixing and dissipation of the kinetic energy into heat in 3D. Our results show that the increase of entropy is enhanced with finer numerical resolution and larger perturbation amplitude.
Over the past decade a new type of global climate model (GCM) has emerged, which is known as a multiscale modeling framework (MMF). Colorado State University's MMF represents a coupling between the ...Community Atmosphere Model and the System for Atmospheric Modeling (SAM) to serve as the cloud‐resolving model (CRM) that replaces traditionally parameterized convection in GCMs. However, due to the high computational expense of the MMF, the grid size of the embedded CRM is typically limited to 4 km for long‐term climate simulations. With grid sizes this coarse, shallow convective processes and turbulence cannot be resolved and must still be parameterized within the context of the embedded CRM. This paper describes a computationally efficient closure that aims to better represent turbulence and shallow convective processes in coarse‐grid CRMs. The closure is based on the assumed probability density function (PDF) technique to serve as the subgrid‐scale (SGS) condensation scheme and turbulence closure that employs a diagnostic method to determine the needed input moments. This paper describes the scheme, as well as the formulation of the eddy length which is empirically determined from large eddy simulation (LES) data. CRM tests utilizing the closure yields good results when compared to LESs for two trade‐wind cumulus cases, a transition from stratocumulus to cumulus, and continental cumulus. This new closure improves the representation of clouds through the use of SGS condensation scheme and turbulence due to better representation of the buoyancy flux and dissipation rates. In addition, the scheme reduces the sensitivity of CRM simulations to horizontal grid spacing. The improvement when compared to the standard low‐order closure configuration of the SAM is especially striking.
Key Points
Simplified PDF parameter just as good as predictive
New turbulence length scale functions well for boundary layer clouds
Better representation of boundary layer clouds
Decadal and bi-decadal climate responses to tropical strong volcanic eruptions (SVEs) are inspected in an ensemble simulation covering the last millennium based on the Max Planck Institute—Earth ...system model. An unprecedentedly large collection of pre-industrial SVEs (up to 45) producing a peak annual-average top-of-atmosphere radiative perturbation larger than −1.5 Wm
−2
is investigated by composite analysis. Post-eruption oceanic and atmospheric anomalies coherently describe a fluctuation in the coupled ocean–atmosphere system with an average length of 20–25 years. The study provides a new physically consistent theoretical framework to interpret decadal Northern Hemisphere (NH) regional winter climates variability during the last millennium. The fluctuation particularly involves interactions between the Atlantic meridional overturning circulation and the North Atlantic gyre circulation closely linked to the state of the winter North Atlantic Oscillation. It is characterized by major distinctive details. Among them, the most prominent are: (a) a strong signal amplification in the Arctic region which allows for a sustained strengthened teleconnection between the North Pacific and the North Atlantic during the first post-eruption decade and which entails important implications from oceanic heat transport and from post-eruption sea ice dynamics, and (b) an anomalous surface winter warming emerging over the Scandinavian/Western Russian region around 10–12 years after a major eruption. The simulated long-term climate response to SVEs depends, to some extent, on background conditions. Consequently, ensemble simulations spanning different phases of background multidecadal and longer climate variability are necessary to constrain the range of possible post-eruption decadal evolution of NH regional winter climates.
The polycyclic aromatic hydrocarbon (PAH), benzoapyrene (BaP), was compared to dibenzodef,pchrysene (DBC) and combinations of three environmental PAH mixtures (coal tar, diesel particulate and ...cigarette smoke condensate) using a two stage, FVB/N mouse skin tumor model. DBC (4nmol) was most potent, reaching 100% tumor incidence with a shorter latency to tumor formation, less than 20weeks of 12-O-tetradecanoylphorbol-13-acetate (TPA) promotion compared to all other treatments. Multiplicity was 4 times greater than BaP (400nmol). Both PAHs produced primarily papillomas followed by squamous cell carcinoma and carcinoma in situ. Diesel particulate extract (1mg SRM 1650b; mix 1) did not differ from toluene controls and failed to elicit a carcinogenic response. Addition of coal tar extract (1mg SRM 1597a; mix 2) produced a response similar to BaP. Further addition of 2mg of cigarette smoke condensate (mix 3) did not alter the response with mix 2. PAH-DNA adducts measured in epidermis 12h post initiation and analyzed by 32P post‐labeling, did not correlate with tumor incidence. PAH‐dependent alteration in transcriptome of skin 12h post initiation was assessed by microarray. Principal component analysis (sum of all treatments) of the 922 significantly altered genes (p<0.05), showed DBC and BaP to cluster distinct from PAH mixtures and each other. BaP and mixtures up-regulated phase 1 and phase 2 metabolizing enzymes while DBC did not. The carcinogenicity with DBC and two of the mixtures was much greater than would be predicted based on published Relative Potency Factors (RPFs).
► Dibenzodef,pchrysene (DBC), 3 PAH mixtures, benzoapyrene (BaP) were compared. ► DBC and 2 PAH mixtures were more potent than Relative Potency Factor estimates. ► Transcriptome profiles 12hours post initiation were analyzed by microarray. ► Principle components analysis of alterations revealed treatment-based clustering. ► DBC gave a unique pattern of gene alterations compared to BaP and PAH mixtures.
The objective of this study, which was part of an integrated project to investigate the antimicrobial effects of dietary tannins on native food borne pathogens in beef cattle, was to examine the ...effects of source of tannin (condensed, CT,
vs. hydrolysable, HT) on performance, feed efficiency, ruminal fermentation parameters, and carcass and non-carcass traits in finishing beef steers. Thirty-six crossbred steers averaging 414
±
40
kg BW were stratified by initial BW and randomly assigned to one of three treatments: control (CN), CT, or HT tannins. Commercially available tannin extracts were added to a high-grain diet (ME
=
11.9
MJ/kg DM) at 14.9
g/kg DM. Mimosa and chestnut extracts provided condensed tannin and hydrolysable tannin, respectively. Steers were individually fed using Calan gate feeders a high-grain diet. Rumen fluid was collected on days 0, 21, and 42
via stomach tube and analyzed for VFA and
in vitro methane producing activity. Cattle were harvested at the end of the study and carcass data collected 24-h postharvest. There was no effect (
P>0.05) of tannin supplementation on animal performance, ruminal fermentation parameters,
in vitro methane producing activity, or carcass and non-carcass traits, except for HCW, EBW, and rumen mass and empty GIT (g/kg EBW). Condensed tannin steers had 3.7% lower (
P<0.05) HCW compared to CN with HT steers having intermediate HCW. Hydrolysable tannin treated steers had 2.8% lower (
P<0.05) EBW compared to CN while CT steers had intermediate EBW; CT treated steers also had 15.2% higher (
P<0.05) rumen mass (g/kg EBW) compared to HT with CN steers being intermediate. This resulted in a 10.2% increase (
P<0.05) in total empty GIT (g/kg EBW) for HT steers compared to CT steers with CN steers bring intermediate. There was a treatment
×
day interaction for butyrate concentration. For steers fed CT, there was a linear increase in butyrate while the HT steers remained relatively stable and the control steers had numerically lower butyrate. Despite the significant interaction, treatment means on day 42 were not significantly different. Results indicate that neither source of dietary tannin affected performance and feed efficiency. There were no detrimental effects of tannins on other offal measured indicating that tannins supplementation may be a viable option in finishing beef cattle if bactericidal efficacy is established. More research is needed to further our understanding of how tannin supplementation may fit into real-life feedlot situations.
The preconditioning of major sudden stratospheric warmings (SSWs) is investigated with two long time series using reanalysis (ERA‐40) and model (MAECHAM5/MPI‐OM) data. Applying planetary wave ...analysis, we distinguish between wavenumber‐1 and wavenumber‐2 major SSWs based on the wave activity of zonal wavenumbers 1 and 2 during the prewarming phase. For this analysis an objective criterion to identify and classify the preconditioning of major SSWs is developed. Major SSWs are found to occur with a frequency of six and seven events per decade in the reanalysis and in the model, respectively, thus highlighting the ability of MAECHAM5/MPI‐OM to simulate the frequency of major SSWs realistically. However, from these events only one quarter are wavenumber‐2 major warmings, representing a low (∼0.25) wavenumber‐2 to wavenumber‐1 major SSW ratio. Composite analyses for both data sets reveal that the two warming types have different dynamics; while wavenumber‐1 major warmings are preceded only by an enhanced activity of the zonal wavenumber‐1, wavenumber‐2 events are either characterized by only the amplification of zonal wavenumber‐2 or by both zonal wavenumber‐1 and zonal wavenumber‐2, albeit at different time intervals. The role of tropospheric blocking events influencing these two categories of major SSWs is evaluated in the next step. Here, the composite analyses of both reanalysis and model data reveal that blocking events in the Euro‐Atlantic sector mostly lead to the development of wavenumber‐1 major warmings. The blocking–wavenumber‐2 major warming connection can only be statistical reliable analyzed with the model time series, demonstrating that blocking events in the Pacific region mostly precede wavenumber‐2 major SSWs.
Key Points
Analysis of the preconditioning of major SSWs by different planetary waves
Planetary wave dynamics of wavenumber‐1 and wavenumber‐2 major SSWs
Influence of tropospheric blockings on wavenumber‐1 and wavenumber‐2 major SSWs
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