Surgery – Diagnostic testing – Cardiovascular
Reexamination Certificate
1999-07-09
2001-12-11
Lacyk, John P. (Department: 3736)
Surgery
Diagnostic testing
Cardiovascular
C600S505000, C600S003000
Reexamination Certificate
active
06328700
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally pertains to chemical or elemental markers or tracers that, when combined with other chemical admixtures or compounds, or when inserted into or upon objects or devices, thereafter serve to permanently identify such admixtures, compounds, objects or devices, including after such change(s) and gross change(s) to the compounds, objects or devices in form and/or in composition as may be occasioned by lapse of. time, dissipation, wear, deterioration, oxidation, or explosion.
The present invention particularly concerns (i) elemental or chemical markers that are indefinitely long lasting, and detectable at the level of a single atom or molecule over a fast range of densities; (ii) the use of neutron activation in the detection of elemental and chemical markers, and the elemental or chemical markers so detectable; and (iii) the packaging of, and/or carriers for, neutron-activation-detectable elemental and/or chemical markers, including the packaging of elemental and/or chemical markers in carrier microspheres, including microspheres as are used in biological experimentation including, inter alia, in blood flow analysis.
2. Description of the Prior Art
2.1 Neutron Activation Analysis
The present invention will be seen to employ neutron activation analysis.
Individual stable elements (e.g., gold) are known to have isotopes that are strongly detectable by neutron activation analysis. The known abundance of the “marker” elements in certain substances has permitted these elements to serve as markers for the substances. See Kennelly, J. J., Apps, M. J., Turner, B. V. and Aherne, F. X. 1980
; Dysprosium, cerium and chromium marker determination by instrumental neutron activation analysis
. Can. J. Anim. Sci. 60:749-761. See also Nishiguchi Y., Sutoh M., Nishida T., Satoh H., Miyamoto S.;
Neutron activation analysis of Lanthanides (La, Sm and Yb) as a particle marker, and estimation of passage rates
. Anim. Sci. Technol. (Jpn.), 67: 787-793. 1996.
Neutron activation analysis can provide the life science community with capabilities not readily available with other assay technologies. Neutron activation is well known for both (i) its excellent sensitivity and (ii) its specificity for the simultaneous measurement of multiple elemental trace elements. This specificity offers the potential of being able to measure multiple isotopic tracers per assay.
Unlike light, neutrons can penetrate solid tissue and opaque-liquid samples, thereby providing an assay that is completely self-contained with but minimal sample preparation.
Unlike other element detection methods, such as atomic absorption spectrophotometry, neutron activation is not chemically or physically destructive. Therefore, samples can be archived, re-assayed, and/or undergo additional chemical analysis following neutron activation.
Because only the samples of interest are neutron activated, assay by neutron activation analysis can significantly reduce-occupational exposure to radiation and eliminate the low-level radioactive waste generated. For example, the contamination of gloves and protective clothing, glass and plastic laboratory supplies, and waste products from research animal housing and carcasses attendant upon the use of radioactive tracers are completely avoided. Stable isotopes do not undergo further radioactive decay or cause radiokinistics and, unlike some colorometric probes, they do not suffer any loss of activity (i.e., loss of fluorescence) over time. Therefore, stable isotope labeled products will have an indefinitely long shelf life: significantly longer than competing labeling methods.
The major disadvantage to assay by neutron activation technology is the required access to a neutron source. If the neutron radiation source is to be strong (i.e., with a high flux) so that it will excite a significant proportion of the target tracers—preferably stable isotopes—of the sample—which sample may be sparse—to an excited, radioactive, energy level in a reasonable time, providing thereby a reasonable population of radionuclides the decay of which may likewise be detected during a reasonable time, then the source of neutron flux must most commonly be energetic, as is typically derived from a research reactor. Suitable research reactors, and reactor time, are not scarce in the United States circa 1999. However, the reactors are located at particular sites not normally coincident with sites at which investigations in the life sciences are conducted. Therefore, samples for assay by neutron activation analysis must normally be sent to a reactor, irradiated with neutron flux, and analyzed with results being reported to the sender. Furthermore, the samples, if not permanently archived at or near the site of the reactor, may be returned to the sender only when radiation has sufficiently abated.
Accordingly, and despite the many advantages of neutron activation, this general analytical tool has not (as of 1999) reached its full potential within the life science community due to some combination of (i) a lack of user awareness of the technique, (ii) a lack or perceived lack of access to reactors, and/or, importantly to the present invention, (iii) a lack of commercially available stable-labeled research products specifically designed for neutron activation technology. These research products would desirably be targeted on intended biological research applications, and be of a form familiar to biological researchers.
Most recently, BioPhysics Assay Laboratory, Inc., 280 Wellesley Avenue, Wellesley Hills, Mass. 02481 (Phone/Fax: (781) 239-0501) [“BioPAL”] has been formed to (i) develop, manufacture and market a new generation of high-precision stable-labeled research products, and to (ii) provide a state-of-the-art assay service that can meet commercial demand. The present invention will be seen to concern these stable-labeled research products, developed jointly with Triton Technology, Inc., of San Diego, Calif.
In passing, it should be noted that neutron activation analysis also has an extensive history in the detection of explosives—which is a different thing than the detection of stable isotopes, used as makers, that may be placed into, inter alia, explosives as will be taught by the present invention. In other words, certain chemicals present in certain explosives can be directly detected by neutron activation analysis. As a leading book on this topic, see
Explosive detection using fast neutron activation analysis
by Terry E. Carrell, published by North American Rockwell, Los Angeles, Calif.
When the present invention is later understood to be stable-isotope labeled microspheres usable as markers in diverse circumstances, it will be useful to consider the possible use of these markers in labeling explosives. Stable-isotope labeled microspheres serving as identifying markers cannot be assured to be emplaced in explosives save those legitimately produced, and then only under mandate of law or regulation.
However, in accordance with the general principles of the present invention, later explained, to the effect that the carriage, and the chemistry, of the marker stable isotope is divorced from the chemistry of the exterior surface of a microsphere which serves to mechanically retain the marker stable isotope, it can be anticipated, in advance, that ubiquitous, tailored, stable-isotope labeled microspheres in accordance with the present invention will be very useful for permanently marking an immense number of different admixtures, compounds, objects or devices, including, inter alia, explosives. Properly tailored to a target, including an explosive, about the only way of expunging microspheres and any elemental markers that they contain from a compound such as an explosive is by gross molecular dissociation such as is characteristic of, inter alia, explosion. Of course, to remove the microspheres, and markers, requires destruction of the compound. Moreover, such explosion and attendant molecular dissociation does not truly get rid of the elem
Kemper W. Scott
Rheinhardt Christopher
Carter Ryan
Fuess & Davidenas
Lacyk John P.
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