Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving antigen-antibody binding – specific binding protein...
Reexamination Certificate
2001-07-20
2004-11-23
Chin, Christopher L. (Department: 1641)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving antigen-antibody binding, specific binding protein...
C435S005000, C435S007900, C436S518000, C436S172000
Reexamination Certificate
active
06821738
ABSTRACT:
TECHNICAL FIELD
The present invention relates to real-time or near real-time detection in gases or fluids of nerve agents of the sort commonly encountered in chemical warfare agents.
BACKGROUND
Often referred to as the “poor man's nuclear weapon”, chemical and biological weapons of war are so named because they cost much less than real nuclear weapons to develop, do not require a high level of technology to produce, and can potentially kill enormous numbers of people. Indeed, unlike nuclear weapons, which require a large, specialized, and costly scientific-industrial base, chemical and biological agents can be made with commercial equipment generally available to any country. Weapons of this sort are especially attractive for use by developing countries against super powers, as they tend to level the playing field in struggles against these better armed and trained opponents. The use of biological and chemical weapons of mass destruction is banned by international treaty, but reports of suspected and confirmed use continue.
Biological weapons can be produced from widely available pathogens which may be procured for legitimate biomedical research or obtained from soil or infected animals and humans. Moreover, many of the infectious diseases associated with biological warfare are endemic to most of the states suspected of developing a biological weapon capability. Biological agents are thus both cheap and easy to obtain: in effect, any nation with a basic pharmaceutical industry—or even a facility such as a brewery—has the capability of producing biological weapons.
Biological agents contain either living organisms or their derivatives, such as toxins, which cause disease or death in humans, animals, or food crops. Living organisms multiply within the living targets to produce their effects, whereas toxins cannot reproduce themselves. Toxins are generally more lethal, and act relatively quickly causing incapacitation or death within minutes or hours. Living organisms (microbial pathogens), require incubation periods of from 24 hours to 6 weeks between infection and appearance of symptoms. This incubation period places limits on their battlefield utility, but it also means that biological weapons can continue to have a significant impact many weeks after the initial attack (e.g., by causing a long-term pandemic). Likewise, this delayed incubation period may mean that a biological attack can be completed before those on the ground have realized that it has occurred, or even take place entirely covertly, the effects being confused with a natural outbreak of disease.
Biological agents are odorless, tasteless, and when dispersed in an aerosol cloud, are invisible to the human eye because the particle size of the aerosol is extremely small—as small as 1 to 5 micrometers or microns. Weight-for-weight, biological weapons are hundreds to thousands of times more potent than the most lethal chemical weapon, meaning that even small amounts (e.g., a few kilograms) could be used with devastating effect, whereas hundreds or thousands of tons of chemical agents could be required for militarily significant operations.
Among lethal chemical warfare agents, nerve agents have played a dominant role since the Second World War. Nerve agents are so-called because they affect the transmission of nerve impulses within the nervous system. Nerve agents belong chemically to the group of organo-phosphorus (“OP”, hereinafter) compounds. OP compounds are stable, easily dispersed, highly toxic, and take effect rapidly both when absorbed through the skin and via respiration. They can be manufactured by means of fairly simple chemical techniques and the raw materials to manufacture them are inexpensive and generally readily available. Sarin, one of the more familiar nerve agents, dates from the Second World War and is considered a “classic” substance. In the mid-1950's, however, a group of more stable nerve agents known was the V-agents were developed, with VX being one of the more successful variants. These later-day chemical weapons are approximately ten-fold more poisonous than sarin and are thus among the most toxic substances ever synthesized.
Nerve agents in pure state are colorless liquids with volatiles that vary depending on the particular compound. The consistency of VX may be likened to a non-volatile oil and is therefore classified as belonging to the group of persistent chemical warfare agents. It enters the body mainly through direct contact with the skin. Sarin is at the opposite extreme, being a relatively volatile liquid (comparable with, e.g., water), and is mainly taken up through the respiratory organs.
The nerve agent, either as a gas, aerosol or liquid, enters the body through inhalation or through the skin. Poisoning may also occur through consumption of liquids or foods contaminated with nerve agents. The route through which the poison enters the body largely determines the time required for the nerve agent to begin having an effect. It also influences the symptoms developed and, to some extent, the sequence of the different symptoms. Generally, poisoning takes place more rapidly when the agent is absorbed through the respiratory system than when it enters via other routes such as the skin. This is because the lungs contain numerous blood vessels which provide for rapid assimilation and transmission to the target organs. Nerve agents are more or less fat-soluble and can penetrate the outer layers of the skin. However, it takes some time before the poison reaches the deeper blood vessels. Consequently, the first symptoms may not appear until 20-30 minutes after the initial exposure. Chemically, nerve agents act by binding to an enzyme in the body of the victim, acetylcholinesterase, which inhibits this vital enzyme's normal biological activity in the cholinergic nervous system. Acetylcholinesterase (“AChE”) terminates nerve impulse transmission at cholinergic synapses by hydrolyzing the neurotransmitter acetylcholine to acetate and choline. Organophosphate compounds such as insecticides and nerve agents inhibit AChE, which inhibition results in a build up of acetylcholine, thereby causing constant transmission of nerve signals.
Most recent research in the area of chemical and biological weapons has been focused on the detection and treatment of exposed individuals rather than the creation of new agents. Because the length of time that an individual is exposed to the agent can be determinative of the likelihood of successful treatment, rapid recognition that an exposure has occurred may mean the difference between life and death. Of course, this recognition/identification time includes not only the time required to perform the necessary diagnostic or chemical tests, but also the time required to move the victim or exposed item to a testing station or facility (or to move the testing unit to the victim, in some cases).
Certainly, there are any number of methods for detecting specific oganophosphate compounds in water or air. However, the methods suggested heretofore for are either too slow to make them useful for real time detection, or too bulky to be easily transported to a location near the front lines, where an attack would normally first be registered. For example, one common method of determining the presence of an OP compound is to measure the biochemical activity of acetylcholinesterase; if OP is present, the activity per enzyme molecule present decreases. However, this method is very slow and it might require days to get the sample to the lab and complete the tests. Additionally, even if conventional transportable units were fast enough to make them useful in real-time, they are too bulky to be distributed to and carried by every soldier which would be, of course, the best method of distribution. Further, most traditional methods of detecting nerve-type agents are designed to respond to one (or a few) specific compounds, which creates certain risks for in-field use, where the particular nerve gas variant might be different than expected
Heretofore, as is well known i
Chin Christopher L.
Fellers Snider Blankenship Bailey & Tippens, P.C.
Lam Ann Y
The Board of Regents for Oklahoma State University
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