Effect of Ascending an Ordinary Flight of Stairs on the Work of the Heart Observations on Normal Individuals and on Patients withCoronary Heart Disease By JAMESA. L. MATHERS,M.D.,HAROLD I. GRIFFEATH,M.D.,ROBERTL.LEVY,M.D., AND JOHNL. NICKERSON,PH.D.he blood pressure cuff andelectrocardiograplhic electrodes remained on the ex-tremities during the exercise to facilitate the speedof making the observations during the recovery period. All obstructions, such as closed doors andotherpersons, wereremoved fromthe path ofthesub-ject being tested.
Restriction enzymes, also known as restriction endonucleases, are enzymes that cut a DNA molecule at a particular place. They are essential tools for recombinant DNA technology. The enzyme scans a DNA molecule, looking for a particular sequence, usually of four to six nucleotides. Once it finds this recognition sequence, it stops and cuts the strands. This is known as enzyme digestion. On double stranded DNA the recognition sequence is on both strands, but runs in opposite directions.
These restriction enzymes are able to scan along a length of DNA looking for a particular sequence of bases that they recognize. This recognition site or sequence is generally from 4 to 6 base pairs in length. Once it is located, the enzyme will attach to the DNA molecule and cut each strand of the double helix.The restriction enzyme will continue to do this along the full length of the DNA molecule which will then break into fragments.hese restriction enzymes are able to scan along a length of DNA looking for a particular sequence of bases that they recognize. This recognition site or sequence is generally from 4 to 6 base pairs in length. Once it is located, the enzyme will attach to the DNA molecule and cut each strand of the double helix.