Range of normal values for left and right ventricular ejection fraction at rest and during exercise assessed by radionuclide angiocardiography

In order to reach a world-wide consensus on the normal range of left (LV) and right ventricular (RV) ejection fraction (EF) at rest and during exercise, pooled data of 1200 normal subjects from 28 leading centres in the field of nuclear cardiology (68% of those contacted) was analysed. Weighted mean normal values for LVEF at rest were 62.3±6.1% (1SD) with a lower limit of normal of 50% and for RVEF 52.3±6.2% (N=365) with a lower limit of normal of 40%. During exercise, LVEF increased in 475 subjects by +8.0 EF% (range 3-15%), a normal increase being accepted to be ≥5% over a normal resting value for both LVEF and RVEF. Subgroup analysis of results at rest revealed no significant differences regarding selection of normal subjects (based on normal catheterization findings vs. normal volunteers with low probability of disease), age or sex. During exercise, however, significantly larger increases in LVEF measurements were noted for men versus women (P<0.01), for normal volunteers versus subjects selected as ‘normals' based on a normal coronary angiogram (P<0.001) and for younger versus older subjects (P<0.001). Data on reproducibility and variability showed that radionuclide angiocardiography can be considered to be a reliable method today. No consensus was found for measurements of regional LV function or wall motion mainly because of differences in methodology used. These normal values may serve as general guidelines for future applications of these techniques but factors which may influence the normal range as defined and discussed in this study should be recognize

Clouds, shadows, or twilight? Mayfly nymphs recognise the difference

1. We examined the relative changes in light intensity that initiate night-time locomotor activity changes in nymphs of the mayfly, Stenonema modestum (Heptageniidae). Tests were carried out in a laboratory stream to examine the hypothesis that nymphs increase their locomotion in response to the large and sustained reductions in relative light intensity that take place during twilight but not to short-term daytime light fluctuations or a minimum light intensity threshold. Ambient light intensity was reduced over a range of values representative of evening twilight. Light was reduced over the same range of intensities either continuously or in discrete intervals while at the same time nymph activity on unglazed tile substrata was video recorded. 2. Nymphs increased their locomotor activity during darkness in response to large, sustained relative light decreases, but not in response to short-term, interrupted periods of light decrease. Nymphs did not recognise darkness unless an adequate light stimulus, such as large and sustained relative decrease in light intensity, had taken place. 3. We show that nymphs perceive light change over time and respond only after a lengthy period of accumulation of light stimulus. The response is much lengthier than reported for other aquatic organisms and is highly adaptive to heterogeneous stream environments

Cooperativity of Glucocorticoid Response Elements Located Far Upstream of the Tyrosine Aminotransferase Gene

Two glucocorticoid response elements (GREs) located 2.5 kb upstream of the transcription initiation site of the tyrosine aminotransferase gene were identified by gene transfer experiments and shown to bind to purified glucocorticoid receptor. Although the proximal GRE has no inherent capacity by itself to stimulate transcription, when present in conjunction with the distal GRE, this element synergistically enhances glucocorticoid induction of gene expression. Cooperativity of the two GREs is maintained when they are transposed upstream of a heterologous promoter. An oligonucleotide of 22 bp representing the distal GRE is sufficient to confer glucocorticoid inducibility. As evidenced by the mapping of DNAase I hypersensitive sites, local alterations in the structure of chromatin at the GREs take place as a consequence of hormonal treatment

Inhibition of activin/nodal signalling is necessary for pancreatic differentiation of human pluripotent stem cells

Peer reviewedPublisher PD

An Ace Up Their Sleeve or a House of Cards: Can the EPA\u27s Affordable Clean Energy Rule Withstand Chevron Deference?

The U.S. Court of Appeals for the District of Columbia (D.C. Circuit) is poised to become a prime battleground in a fight over the scope of the Environmental Protection Agency \u27s (EPA) authority to regulate greenhouse gas emissions (GHGs) from the power sector under the Clean Air Act (CAA). The dispute stems from the EPA\u27s recent efforts to replace the Obama-era Clean Power Plan (CPP) with the Affordable Clean Energy Rule (ACE Rule). This move was quickly challenged by a coalition of twenty-nine cities and states as well as several prominent American health associations. The two rules reflect very different views in regards to the role the federal government should play in combatting climate change, yet the core legal questions they pose are quite similar

Can the Expansion of 45Q Effectively Spur Investment in Carbon Capture?

Carbon capture technologies play a critical role in the global effort to mitigate carbon dioxide (C02) emissions. Even with significant advancements in energy efficiency and an increase in renewable energy generation, the international community will not be able to meet critical climate goals without a strong carbon capture portfolio. Moreover, it is one of the few technologies capable of reducing emissions from the fossil fuel industry which is expected to remain a significant player in the energy sector well into the middle of the century. Despite this, there have been few federal incentives for carbon capture, and those that exist have proven largely insufficient for supporting commercial deployment