In the resting cell, DNA is tightly compacted to prevent transcription factor accessibility. During activation of the cell, this compact inaccessible DNA is made available to DNA-binding proteins, thus allowing the induction of gene transcription (1 ,2). DNA is packaged into chromatin, a highly organized and dynamic protein-DNA complex. The fundamental subunit of chromatin, the nucleosome, is composed of an octomer of four core histones, an H3/H4 tetramer and two H2A/H2B dimers, surrounded by 146 bp DNA (2,3). The packaging of DNA into nucleosomes acts as a barrier to the initiation of transcription by preventing the access of transcriptional factors, and RNA polymerase II, to their cognate recognition sequences (4). Specific lysine residues in the N-terminal tails of the core histone can be post-translationally modified by acetylation of the ε-amino group. The dynamic equilibrium of core histone acetylation is established and maintained by histone acetyltransferase (HAT) and histone deacetylase (HDAC). Several transcriptional regulators possess intrinsic HAT and HDAC activities, strongly suggesting that histone acetylation and deacetylation play a causal role in regulating transcription (5-8). There is compelling evidence that increased gene transcription is associated with an increase in histone acetylation; hypoacetylation of histone is correlated with reduced transcription or gene silencing (2 ,7,8; Fig 1).
The purpose of this project was to update competencies for spiritual care professionals specializing in palliative and bereavement care in Canada. Phase one feedback was obtained from 11 clients: six inpatients with greater than two weeks of life expectancy using interviews and five bereaved family members in a focus group. Results were analyzed for congruence or discordance with draft competencies. In phase two, 22 spiritual care experts reached a consensus on nine competencies using a modified Delphi survey. Two limitations were the small sample size and cultural and religious homogeneity of participants.
Restenosis of the dilated vessel after percutaneous transluminal coronary angioplasty can be detected by non-invasive procedures but their ability to predict later restenosis soon after a successful angioplasty as well as recurrence of angina has not been assessed. A maximal exercise test and myocardial thallium perfusion scintigraphy were, therefore, performed in 91 asymptomatic patients a median of 5 weeks after they had undergone a technically successful angioplasty. Primary success of the procedure was confirmed by the decrease in percentage diameter stenosis from 64(12)% to 30(13)% as measured from the coronary angiograms and in the trans-stenotic pressure gradient (normalised for mean aortic pressure) from 0.61(0.16) to 0.17(0.09). A clinical follow up examination (8.6(4.9) months later) was carried out in all patients and a late coronary angiogram obtained in 77. The thallium perfusion scintigram showing the presence or absence of a reversible defect was highly predictive for restenosis whereas the exercise test was not. The positive predictive value of an abnormal scintigram was 82% compared with 60% for the exercise test (ST segment depression/or angina or both at peak workload). Angina or a new myocardial infarction occurred in 60% of patients with abnormal and in 21% of patients with normal scintigrams.
No abstract is provided for this article.
No abstract is provided for this article.
Abstract The mechanical behaviour and design of fixed‐ended steel equal‐leg angle section members subjected to axial compression are addressed in this study. First, the critical buckling behaviour is described. Experimental data on steel equal‐leg angle section columns collected from the literature are then used for the validation of numerical (shell finite element) models, developed within the commercial package ABAQUS. Validation is performed by means of comparisons between the test and numerical results, considering ultimate loads, failure modes and the load‐deformation responses, all of which are shown to be generally in good agreement. A numerical parametric study is then presented considering steel angle section columns with a wide range of slenderness values. The behaviour and load‐carrying capacity of the columns is shown to be dependent on, not only the column slenderness, but also the ratio of the elastic torsional‐flexural buckling load to the elastic minor‐axis flexural buckling load. Finally, the collected experimental and generated numerical results are used to develop a new design approach for fixed‐ended steel equal‐leg angle section columns, reflecting the observations made. The proposed approach offers improved accuracy and consistency in strength predictions compared to the existing codified design rules.
