Electric heating – Microwave heating – With diverse device
Reexamination Certificate
2002-04-23
2004-09-28
Van, Quang T (Department: 3742)
Electric heating
Microwave heating
With diverse device
C219S687000, C219S762000
Reexamination Certificate
active
06797928
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a methodology and apparatus for rapid tissue decalcification and fixation employing a microwave (“MW”) oven with variable adjustable low wattage, a specialized tissue handling device and external reagent temperature control to gain the maximum benefit of MW irradiation without the heating problems associated with other MW methods.
BACKGROUND OF THE INVENTION
Clinical and research analysis of tissue samples is an ongoing science. Bone tissue samples require that the calcium be removed prior to sectioning of tissue for microscopic analysis. In prior art it is known that MW irradiation of tissue samples will accelerate the process of decalcification and fixation when compared to routinely accepted bench tissue specimen processing methods. Prior art methods immerse a tissue sample in a reagent in a container placed in a MW oven. Prior art reagents include fixatives, acids, and chelators, as well as mixtures of those reagents. Prior art has demonstrated that use of corrosive acids must be carefully monitored and controlled to avoid tissue specimen destruction. Known MW irradiation methods require reagent changes for each one of multiple runs of the MW process. In prior art, elevated temperatures are commonly used for each cycle. Using prior art, MW-assisted/temperature-based processing methods have required these multiple reagent changes and a temperature control between 37° C. and 45° C. to maintain best sample quality, although prior art also demonstrates use of much higher temperatures. It has been demonstrated in prior art that temperatures above 45° C. have accelerated the process further, but also has demonstrated tissue damage at those temperatures. Temperature control, by whatever means, is done by turning the magnetron on and off at an uncontrolled rate to maintain a preset temperature maximum. Using this known approach, the amount of MW energy applied to the sample will vary from run to run. These MW assisted methods, by necessity, rely on a temperature maximum or restriction that is above the ambient temperature to insure that the magnetron would activate and produce microwaves.
Time savings in processing samples will have a direct effect on surgical and clinical pathology, drug development and basic research in a wide range of fields from veterinary to human medicine and clinical pathology as well as research in medicine and the pharmaceutical industry. Reduction in times when using MW processing over established room temperature methods have been reported to be from 10 to 100 fold.
What is needed is a decalcification and fixation methodology that: 1) Utilizes a range of wattage between 50 w and 750 w MW processing; 2) uses a reagent circulation system as opposed to a static immersion system; 3) uses non-corrosive reagents; and 4) creates time saving as addressed above while producing quality and consistent results. The present invention addresses each of these needs.
SUMMARY OF THE INVENTION
The main aspect of the present invention is to provide an improved method for decalcification and fixation of mineralized samples utilizing apparatus consisting of off-the-shelf components that control all processing variables.
Another aspect of the present invention is to provide standardization of the described process across the clinical and research community.
Another aspect of the present invention is to provide a MW-assisted method not relying on MW heating as a component of the process but consisting of a continuous MW energy during the entire process.
Another aspect of the present invention is to provide for adjustment of the wattage output of the MW oven to optimize tissue decalcification and fixation turn-around time.
Another aspect of the present invention is to provide a system that, for the first time, controls all processing parameters in the decalcification and fixation of tissue. Such parameters include the amount of MW irradiation, wattage, temperature, time, etc.
Another aspect of the present invention is to provide for the control of all processing variables associated with previously published MW decalcification and fixation methods and test their validity.
Another aspect of the present invention is to increase productivity by reducing tissue sample turn around time in all settings while producing excellent processing results.
Another aspect of the present invention is to provide for a processing method utilizing commonly accepted reagents.
Another aspect of the present invention is to gain a rapid turn around time formerly dependent on the use of corrosive acids by substituting EDTA (ethylenediamine tetraacetic acid) and formalin in a MW environment.
Another aspect of the present invention is to provide an identifiable tissue specimen cassette and a cassette holder (tissue handling device) for holding tissue specimen cassettes in place during processing.
Other aspects of this invention will appear from the following description and appended claims, reference being made to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.
The present invention provides rapid decalcification and fixation of mineralized tissues. The process utilizes a MW oven, which has adjustable wattage output to maintain operation within a narrow set of parameters. Tissue handling and identification with this system can be accomplished by standardized methods combined with a specialized containment device that is both solvent resistant and MW transparent. A MW oven operating at 2.45 GHz was used in the preferred embodiment of the present invention.
Further aspects of the system of the present invention are the variable wattage processing parameters that can be employed, for the first time, in the decalcification and fixation of tissue samples.
The present invention can increase productivity in all settings described and is anticipated to produce excellent processing results when ethylenediamine tetraacetic acid (EDTA) and 10% neutral buffered formalin are combined. EDTA is known to preserve tissue ultrastructure when the decalcification process is accelerated in the MW. Other reagents can be used, some of which are described below.
Further aspects of the present invention speak directly to the problems associated with other MW methods. The invention provides for the control of all processing variables associated with previously published MW decalcification methods. The present invention also suggests a non-thermal MW effect as a processing variable in simultaneous decalcification and fixation procedures.
DETAILED DESCRIPTION OF INVENTION
The present invention utilizes a methodology for decalcification and fixation using off-the-shelf apparatus that consists (but not limited to) the following hardware apparatus and processing methodology:
A. Use of MW oven with a continuous power output range from 50 w to 750 w. Magnetron power settings are adjustable within a narrow range (typically +/−25 w) and maintain internal temperature control to about +/−0.5° C.
B. Use of a wide range of reagents such as EDTA and formalin (or others as acceptable).
C. Use of off-the-shelf hardware processing apparatus such as (but not limited to):
a. MW oven (see above) with adjustments for continuous power outputs of approximately 50 w to 750 w, time, temperature, monitoring probe, and input/output ports for external reagent circulation channels, and processing time control settings between about 1 sec and 100 hours.
b. An external recirculation device for continuous reagent recirculation, mixing, agitation, and temperature control which has both heat and cooling capabilities for the circulating reagent in order to maintain constant temperature, within narrow limits, of the reagent being circulated through a tissue handling device. The external recirculation device has an input and an output hose with a duplex pump to recirculate the reagent as it is being heated or cooled.
c. An internal MW oven processing bath into which is placed a tissue han
Armogida Mark J.
Giberson Richard T.
Hansen Paul A.
Martin Rick
Patent Law Offices of Rick Martin P.C.
Ted Pella, Inc.
Van Quang T
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