Movement of agents

An ionophoie may be defined as an oiganic substance that binds a polar compound and acts as an ion-transfer agent to facilitate movement of... 

The Class I antiarrhythmic agents inactivate the fast sodium channel, thereby slowing the movement of Na" across the cell membrane (1,2). This is reflected as a decrease in the rate of development of phase 0 (upstroke) depolarization of the action potential (1,2). The Class I agents have potent local anesthetic effects. These compounds have been further subdivided into Classes lA, IB, and IC based on recovery time from blockade of sodium channels (11). Class IB agents have the shortest recovery times (t1 ) Class lA compounds have moderate recovery times (t 2 usually <9 s) and Class IC have the longest recovery times (t 2 usually >9 s). 

Regardless of the source, the resultant oil slicks are essentially surface phenomena that are affected by several transportation and transformation processes. With respect to transportation, the principal agent for the movement of slicks is the wind, but length scales are important. Whereas small (i.e. relative to the slick size) weather systems, such as thunderstorms, tend to disperse the slick, cyclonic systems can move the slick essentially intact. Advection of a slick is also affected by waves and currents. To a more limited extent, diffusion can also act to transport the oil. 

Frontier Orbitals and Chemical Reactivity. Chemical reactions typically involve movement of electrons from an electron donor (base, nucleophile, reducing agent) to an electron acceptor (acid, electrophile, oxidizing agent). This electron movement between molecules can also be thought of as electron movement between molecular orbitals, and the properties of these electron donor and electron acceptor orbitals provide considerable insight into chemical reactivity. 

The so-called calcium channel blockers constitute a class of cardiovascular agents that have gained prominence in the past few years. These drugs, which obtund contraction of arterial vessels by preventing the movement of calcium ions needed for those contractions, have proved especially useful in the treatment of angina and hypertension. Dihydropyridines such as nifedipine (30) are par-... 

The inhibitors of RNA polymerase, which generates RNA from DNA, inhibit a crucial step in gene expression. Inhibition of the eukaryotic form of RNA polymerase is used in cancer chemotherapy and is also an important experimental tool. For example, actinomy-cin D binds to the guanine residues in DNA and blocks the movement of the eukaryotic RNA polymerase. Specific inhibitors of bacterial RNA polymerase can be used as antibacterial agents. Most of these inhibitors like rifamycin bind to the prokaryotic enzyme. 

Extravasation Movement of fluid from inside a blood vessel into the surrounding tissues for example, leakage or infiltration of a vesicant chemotherapy agent into local tissue. 

To establish themselves as significant players in the political realm, splinter groups tend to be both more violent and more experimental than their parent groups. For example, Ansar al-Islam, a splinter from the Islamic Movement of Kurdistan (IMK) that associates with al Qaeda, established a lab in northern Iraq to manufacture and test chemical and biological agents, including ricin, for use in terrorist attacks [40]. 

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