Where a poem makes reference to another poem or text. For example, the 14th line of The Prelude by William Wordsworth 'The earth was all before me' alludes to one of the final lines of Paradise Lost by John Milton 'The world was all before them'. Paradise Lost, in turn, alludes to the story of Adam and Eve in Genesis.
Beta-blockers are drugs that bind to beta-adrenoceptors and thereby block the binding of norepinephrine and epinephrine to these receptors. This inhibits normal sympathetic effects that act through these receptors. Therefore, beta-blockers are sympatholytic drugs.
A beta blocker is often used to treat high blood pressure or an irregular heart beat. This medicine can also be used to treat congestive heart failure, but people with severe heart failure may not be able to take a beta blocker. A beta blocker reduces the risk of another heart attack for people who have already had one.