Morphological and Volumetric Analysis of Left Atrial Appendage and Left Atrium: Cardiac Computed Tomography-Based Reproducibility Assessment

Objectives

Left atrial appendage (LAA) dilatation and morphology may influence an individual''s risk for intracardiac thrombi and ischemic stroke. LAA size and morphology can be evaluated using cardiac computed tomography (cCT). The present study evaluated the reproducibility of LAA volume and morphology assessments.

Methods

A total of 149 patients (47 females; mean age 60.9±10.6 years) with suspected cardioembolic stroke/transient ischemic attack underwent cCT. Image quality was rated based on four categories. Ten patients were selected from each image quality category (N = 40) for volumetric reproducibility analysis by two individual readers. LAA and left atrium (LA) volume were measured in both two-chamber (2CV) and transversal view (TV) orientation. Intertechnique reproducibility was assessed between 2CV and TV (200 measurement pairs). LAA morphology (A = Cactus, B = ChickenWing, C = WindSock, D = CauliFlower), LAA opening height, number of LAA lobes, trabeculation, and orientation of the LAA tip was analysed in all study subjects by three individual readers (447 interobserver measurement pairs). The reproducibility of volume measurements was assessed by intra-class correlation (ICC) and the reproducibility of LAA morphology assessments by Cohen''s kappa.

Results

The intra-observer and interobserver reproducibility of LAA and LA volume measurements was excellent (ICCs>0.9). The LAA (ICC = 0.954) and LA (ICC = 0.945) volume measurements were comparable between 2CV and TV. Morphological classification (ĸ = 0.24) and assessments of LAA opening height (ĸ = 0.1), number of LAA lobes (ĸ = 0.16), trabeculation (ĸ = 0.15), and orientation of the LAA tip (ĸ = 0.37) was only slightly to fairly reproducible.

Conclusions

LA and LAA volume measurements on cCT provide excellent reproducibility, whereas visual assessment of LAA morphological features is challenging and results in unsatisfactory agreement between readers.     

Restoration of Young Forests in Eastern Finland: Benefits for Saproxylic Beetles (Coleoptera)

Effective fire suppression in combination with intensive forestry has caused a large number of dead wood‐dependent (saproxylic) species to become threatened in Fennoscandia. In order to return the fire disturbance dynamics and to increase the amount of dead wood, restoration actions are urgently needed. We studied the effects of restoring young (under 30 years old) pine‐dominated (Pinus sylvestris L.) forest stands on saproxylic beetle assemblages in eastern Finland, focusing especially on rare, red‐listed, and pyrophilous (RRLP) species. Our experiment included a restoration treatment including two tree felling levels for fuel load (10 or 20 m³/ha) followed by burning, and an untreated control. We sampled beetles before restoration in 2005, during the year of restoration in 2006, and in two post‐treatment years in 2007 and 2011. Both restoration treatments increased the number of saproxylic and RRLP species. The species richness increased most in the year of restoration in 2006 and this trend continued in the following year 2007, but no differences in species assemblages were detected between the two fuel load levels. By 2011, however, the species richness and abundance had declined back to the pre‐treatment level. We suggest that restoration burning can also be directed to young forests where biodiversity values are initially low. On the basis of the observed decline in the species richness, we suggest that fire could be introduced in neighboring areas in approximately 5‐year intervals to maintain populations of the most demanding pyrophilous species .     

CIP2A oncoprotein controls cell growth and autophagy through mTORC1 activation

mTORC1 (mammalian target of rapamycin complex 1) integrates information regarding availability of nutrients and energy to coordinate protein synthesis and autophagy. Using ribonucleic acid interference screens for autophagy-regulating phosphatases in human breast cancer cells, we identify CIP2A (cancerous inhibitor of PP2A [protein phosphatase 2A]) as a key modulator of mTORC1 and autophagy. CIP2A associates with mTORC1 and acts as an allosteric inhibitor of mTORC1-associated PP2A, thereby enhancing mTORC1-dependent growth signaling and inhibiting autophagy. This regulatory circuit is reversed by ubiquitination and p62/SQSTM1-dependent autophagic degradation of CIP2A and subsequent inhibition of mTORC1 activity. Consistent with CIP2A’s reported ability to protect c-Myc against proteasome-mediated degradation, autophagic degradation of CIP2A upon mTORC1 inhibition leads to destabilization of c-Myc. These data characterize CIP2A as a distinct regulator of mTORC1 and reveals mTORC1-dependent control of CIP2A degradation as a mechanism that links mTORC1 activity with c-Myc stability to coordinate cellular metabolism, growth, and proliferation.     

The Use of Magnetic Resonance Spectroscopy as a Tool for the Measurement of Bi-hemispheric Transcranial Electric Stimulation Effects on Primary Motor Cortex Metabolism

Transcranial direct current stimulation (tDCS) is a neuromodulation technique that has been increasingly used over the past decade in the treatment of neurological and psychiatric disorders such as stroke and depression. Yet, the mechanisms underlying its ability to modulate brain excitability to improve clinical symptoms remains poorly understood ³³. To help improve this understanding, proton magnetic resonance spectroscopy (¹H-MRS) can be used as it allows the in vivo quantification of brain metabolites such as γ-aminobutyric acid (GABA) and glutamate in a region-specific manner ⁴¹. In fact, a recent study demonstrated that ¹H-MRS is indeed a powerful means to better understand the effects of tDCS on neurotransmitter concentration ³⁴. This article aims to describe the complete protocol for combining tDCS (NeuroConn MR compatible stimulator) with ¹H-MRS at 3 T using a MEGA-PRESS sequence. We will describe the impact of a protocol that has shown great promise for the treatment of motor dysfunctions after stroke, which consists of bilateral stimulation of primary motor cortices ^27,30,31. Methodological factors to consider and possible modifications to the protocol are also discussed.     

Afforestation does not necessarily reduce nitrous oxide emissions from managed boreal peat soils

Pristine peatlands have generally low nitrous oxide (N₂O) emissions but drainage and management practices enhance the microbial processes and associated N₂O emissions. It is assumed that leaving peat soils from intensive management, such as agriculture, will decrease their N₂O emissions. In this paper we report how the annual N₂O emission rates will change when agricultural peat soil is either left abandoned or afforested and also N₂O emissions from afforested peat extraction sites. In addition, we evaluated a biogeochemical model (DNDC) with a view to explaining GHG emissions from peat soils under different land uses. The abandoned agricultural peat soils had lower mean annual N₂O emissions (5.5?±?5.4?kg?N?ha^?1) than the peat soils in active agricultural use in Finland. Surprisingly, N₂O emissions from afforested organic agricultural soils (12.8?±?9.4?kg?N?ha^?1) were similar to those from organic agricultural soils in active use. These emissions were much higher than those from the forests on nutrient rich peat soils. Abandoned and afforested peat extraction sites emitted more N₂O, (2.4?±?2.1?kg?N?ha^?1), than the areas under active peat extraction (0.7?±?0.5?kg?N?ha^?1). Emissions outside the growing season contributed significantly, 40% on an average, to the annual emissions. The DNDC model overestimated N₂O emission rates during the growing season and indicated no emissions during winter. The differences in the N₂O emission rates were not associated with the age of the land use change, vegetation characteristics, peat depth or peat bulk density. The highest N₂O emissions occurred when the soil C:N ratio was below 20 with a significant variability within the measured C:N range (13–27). Low soil pH, high nitrate availability and water table depth (50–70?cm) were also associated with high N₂O emissions. Mineral soil has been added to most of the soils studied here to improve the fertility and this may have an impact on the N₂O emissions. We infer from the multi-site dataset presented in this paper that afforestation is not necessarily an efficient way to reduce N₂O emissions from drained boreal organic fields.     

Increased production of xylanase by expression of a truncated version of the xyn11A gene from Nonomuraea flexuosa in Trichoderma reesei

We have previously shown that the Nonomuraea flexuosa Xyn11A polypeptides devoid of the carbohydrate binding module (CBM) have better thermostability than the full-length xylanase and are effective in bleaching of pulp. To produce an enzyme preparation useful for industrial applications requiring high temperature, the region encoding the CBM was deleted from the N. flexuosa xyn11A gene and the truncated gene was expressed in Trichoderma reesei. The xylanase sequence was fused to the T. reesei mannanase I (Man5A) signal sequence or 3' to a T. reesei carrier polypeptide, either the Man5A core/hinge or the cellulose binding domain (CBD) of cellobiohydrolase II (Cel6A, CBHII). The gene and fusion genes were expressed using the cellobiohydrolase 1 (cel7A, cbh1) promoter. Single-copy isogenic transformants in which the expression cassette replaced the cel7A gene were cultivated and analyzed. The transformants expressing the truncated N. flexuosa xyn11A produced clearly increased amounts of both the xylanase/fusion mRNA and xylanase activity compared to the corresponding strains expressing the full-length N. flexuosa xyn11A. The transformant expressing the cel6A CBD-truncated N. flexuosa xyn11A produced about 1.9 g liter-1 of the xylanase in laboratory-scale fermentations. The xylanase constituted about 25% of the secreted proteins. The production of the truncated xylanase did not induce the unfolded protein response (UPR) pathway. However, the UPR was induced when the full-length N. flexuosa xyn11A with an exact fusion to the cel7A terminator was expressed. We suggest that the T. reesei folding/secretion machinery is not able to cope properly with the bacterial CBM when the mRNA of the full-length N. flexuosa xyn11A is efficiently translated.     

Autophagy: an emerging target for cancer therapy

Macroautophagy (hereafter referred to as autophagy) is a lysosomal catabolic pathway whereby cells recycle macromolecules and organelles. The capacity of autophagy to maintain cellular metabolism under starvation conditions and to remove damaged organelles under stress conditions improves the survival of cells. Yet, autophagy appears to suppress tumorigenesis. In this review we discuss recent data that begin to elucidate the molecular basis for this apparent controversy. First, we summarize our current knowledge on the autophagy-mediated control of both cell survival and cell death in general. Then, we highlight the common cancer-associated changes in autophagy induction, regulation and execution. And finally we discuss the potential of pro- as well as anti-autophagic signaling pathways as targets for future cancer therapy.