Increased EEG gamma band activity in Alzheimer’s disease and mild cognitive impairment

High frequency (30–70 Hz) gamma band oscillations in the human electro-encephalogram (EEG) are thought to reflect perceptual and cognitive processes. It is therefore interesting to study these measures in cognitive impairment and dementia. To evaluate gamma band oscillations as a diagnostic biomarker in Alzheimer’s disease (AD) and mild cognitive impairment (MCI), 15 psychoactive drug naïve AD patients, 20 MCI patients and 20 healthy controls participated in this study. Gamma band power (GBP) was measured in four conditions viz. resting state, music listening, story listening and visual stimulation. To evaluate test–retest reliability (TRR), subjects underwent a similar assessment one week after the first. The overall TRR was high. Elevated GBP was observed in AD when compared to MCI and control subjects in all conditions. The results suggest that elevated GBP is a reproducible and sensitive measure for cognitive dysfunction in AD in comparison with MCI and controls

OptCom: A Multi-Level Optimization Framework for the Metabolic Modeling and Analysis of Microbial Communities

Microorganisms rarely live isolated in their natural environments but rather function in consolidated and socializing communities. Despite the growing availability of high-throughput sequencing and metagenomic data, we still know very little about the metabolic contributions of individual microbial players within an ecological niche and the extent and directionality of interactions among them. This calls for development of efficient modeling frameworks to shed light on less understood aspects of metabolism in microbial communities. Here, we introduce OptCom, a comprehensive flux balance analysis framework for microbial communities, which relies on a multi-level and multi-objective optimization formulation to properly describe trade-offs between individual vs. community level fitness criteria. In contrast to earlier approaches that rely on a single objective function, here, we consider species-level fitness criteria for the inner problems while relying on community-level objective maximization for the outer problem. OptCom is general enough to capture any type of interactions (positive, negative or combinations thereof) and is capable of accommodating any number of microbial species (or guilds) involved. We applied OptCom to quantify the syntrophic association in a well-characterized two-species microbial system, assess the level of sub-optimal growth in phototrophic microbial mats, and elucidate the extent and direction of inter-species metabolite and electron transfer in a model microbial community. We also used OptCom to examine addition of a new member to an existing community. Our study demonstrates the importance of trade-offs between species- and community-level fitness driving forces and lays the foundation for metabolic-driven analysis of various types of interactions in multi-species microbial systems using genome-scale metabolic models

Changes in human placental oxygenation during maternal hyperoxia estimated by blood oxygen level-dependent magnetic resonance imaging (BOLD MRI)

Objectives To investigate changes in human placental oxygenation during maternal hyperoxia using non-invasive blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI). Methods Eight healthy pregnant women with uncomplicated singleton pregnancies at gestational weeks 28-36 were examined with BOLD MRI, over two consecutive 5-min periods of different oxygenation: first normoxia (21% O-2) and then hyperoxia (12 L O-2/min), achieved by controlling the maternal oxygen supply with a non-rebreather facial mask. Selecting three slices showing cross-sections of the central part of the placenta, we investigated total placental oxygenation by drawing regions of interest (ROIs) covering the entire placenta, and regional placental oxygenation by drawing smaller ROIs in the darker and brighter areas of the placenta. For each ROI, the difference in BOLD signal between the two episodes was determined and the percentage increase in BOLD signal during hyperoxia (BOLD) was calculated. Results In the BOLD image, the normoxic placenta appeared heterogeneous, with darker areas located to the fetal side and brighter areas to the maternal side. During hyperoxia, the placenta became brighter and the structure more homogeneous, and the BOLD signal of the total placenta increased (BOLDtot, 15.2 +/- 3.2% (mean +/- SD), P<0.0001). The increase was seen predominantly in the dark areas in the fetal part of the placenta (BOLDfet, 32.1 +/- 9.3%) compared with in the bright areas in the maternal part of the placenta (BOLDmat, 5.4 +/- 3.5%). Conclusion During hyperoxia, placental oxygenation was increased predominantly in the darker placental areas, which, given their anatomical location, represent the fetal circulation of the placenta. To our knowledge, this is the first study to successfully visualize changes in placental oxygenation using BOLD MRI. Copyright (c) 2013 ISUOG. Published by John Wiley & Sons Ltd

MRI-based multiscale models for the haemodynamic and structural evaluation of surgically reconstructed aortic arches

Surgical interventions on the arterial wall may bring forth modification to its tissue characteristics and the addition of synthetic materials of different types can have implications on haemodynamics and blood vessel wall behaviour. This work studies the mid-term effects of end-to-end anastomosis (E/E), Gore-tex graft interposition (GGI) and Gore-tex patch graft aortoplasty (GPGA) in aortic arch reconstruction. The study comprises two groups of healthy sows of Danish breed. The animals in the first group (ST) weighed around 40 kg, underwent a surgical operation and were put down on the same day. The animals in the second group (MT) weighed 5-10 kg, underwent a surgical operation and were then allowed to grow up to a weight of around 30-40 kg, before being sacrificed. One pig in each group was scheduled in for E/E and one for GGI. One pig in ST and two in MT received GPGA. The overall average wall thickness was 1.93 mm. Relaxation constant values were significantly higher for ST (5.221 +/- 1.832 s) than for MT (2.184 +/- 1.216 s). GPGA showed a greater impact on relaxation than other operations, enhancing the viscous character. Working-point Young’s modulus (Epw ) was not significantly different in ST and MT. Circumferential samples had different Epw (0.419 +/- 0.77 MPa) from longitudinal ones (0.902 +/- 0.378 MPa). There also appeared to be a significant difference between samples cut longitudinally on the left and the right sides of the wall. The overall average value of Epw was 0.6609 +/- 0.3641 MPa