Patent Application
20050256425
This invention relates to the field of devices for the removal of tissue and particularly brain tissue and a methods of assaying such.
A range of different biopsy devices utilizing needle aspiration to extract tissue samples are known to those skilled in the art. Such devices are useful to obtain samples of tissue, such as tissue suspected of being cancerous. The tissue samples may be examined in order to confirm such suspected diagnosis. Such devices are frequently used when sampling suspected cancerous tissue in the lungs, liver, adrenal glands, kidneys, breasts, and prostate.
Biopsy devices may extract a sample of tissue from a tissue mass by either drawing a tissue sample into a hollow needle via an external vacuum force or by severing and containing a tissue sample within a notch formed in a stylet. Typical of such devices utilizing a vacuum force are U.S. Pat. No. 5,246,011 issued to Cailouette and U.S. Pat. No. 5,183,052 issued to Terwilliger. Such devices contemplate advancing a hollow needle into a tissue mass and applying a vacuum force to draw a sample into the needle and hold the same therein while the tissue is extracted.
Biopsy devices may utilize a biopsy needle with a tissue sample recovery notch formed thereon to extract a specimen, such as described in U.S. Pat. No. 3,477,423 issued to Griffith, often referred to as the TRU-CUT needle and U.S. Pat. No. 4,776,423 issued to Beraha et al.
Specially designed cannulas may be used to enhance the cutting and recovery of tissue samples, as well as combining the application of a vacuum force to draw a tissue sample into a biopsy cavity prior to cutting the tissue contained therein. U.S. Pat. No. 4,708,147 issued to Haaga discloses a cannula for a biopsy needle designed to cut a sample of tissue and then applying a vacuum to the cannula such that the tissue is drawn into the cannula and thus retained therein for recovery. Additionally, U.S. Pat. No. 3,844,272 issued to Banko discloses a biopsy device wherein a suction force, created by a vacuum, draws a sample of tissue into a receiving compartment whereby two coaxial members are rotated relative to each other so that the members essentially coact to cut off the specimen and place it into a compartment.
Many of these devices are complex and expensive to produce and are often reused which requires sterilization of the device after each use. Accordingly, there exists a substantial need in the art to provide a tissue sample extractor capable of effectively and efficiently drawing in a suitable sample of tissue and isolating the tissue sample within the biopsy device. Additionally, there is a need for a biopsy device that is easy to use and can effectively be manipulated by one hand. Furthermore, there is a need in the art to provide a tissue sample extractor that not only provides tissue samples of sufficient size, but allows the sample to be readily placed in a container for treatment and later analysis. Further, it would be of even greater advantage to provide a tissue sample extractor having the above-mentioned features which is also a completely disposable device which can be easily and cheaply manufactured.
A device, system and method for the extraction of brain tissue and its preparation for being subjected to an assay is disclosed. The device is comprised of transparent graduated hollow tube having a tubular metal cuff positioned into one end and a flange or protruding rim at the opposite end. A plunger comprised of a rubber or polymeric material is connected to a first end of a shaft which is positioned inside the hollow tube such that it can be moved to create suction. The shaft may have a flange at its second end allowing for the plunger to be pulled through the tube and create suction. The tubular metal cuff is connected to the hollow tube at its first end. The second or distal end of the cuff has a sharp edge which can be easily forced into brain tissue to cut out a piece of about 0.1 to 10 ml, 0.1 to 2 ml, or 0.1 to 1.0 ml in volume which tissue is pulled into the tube with the aid of the plunger.
An aspect of the invention is a method comprising the steps of:
Yet another aspect of the invention is carried out by repeating steps (a), (b) and (c) a plurality of times wherein a new tissue extraction device is used in each set of repeated steps to extract tissue from another animal which is expelled into a different well.
In accordance with the above method in step (c) the brain sample may be expelled into an individual tube such as a tube having a volume of about 1.5 to 3 or more particularly about 2 ml in volume which is preferably a polypropylene tube containing beads which can be shaken to homogenize the brain. Such a method can be used in accordance with a low through-put system which does not require obtaining large numbers of samples which would be used with the high through-put 96 well plate system.
Once the tissue is extracted it is extruded from the tube by forcing the plunger down. The extruded tissue is placed in a well of a 96 well plate covered with a breakable foil liner. The well contains beads which aid in homogenizing the tissue sample placed therein.
An aspect of the invention is that the tissue extraction device is simple and easy to use for the rapid extraction of tissue.
Another aspect of the invention is that the tissue can be easily and rapidly extruded from the device into the next available well for later treatment.
Yet another aspect of the device is that it is inexpensive and as such can be disposed of after a single use.
These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the device, system and method as more fully described below.
The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures:
Before the present device, system and method is described, it is to be understood that this invention is not limited to particular embodiment described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited.
It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a sample” includes a plurality of such samples and reference to “the assay” includes reference to one or more assays and equivalents thereof known to those skilled in the art, and so forth.
The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
Referring now to
A plunger 8 is comprised of a shaft 9 with a rubber or polymeric stopper 10 inserted inside the tube 3. The shaft 9 has a flange 11 which can be easily pulled to move the stopper 10 toward the end 7 of the tube 3 and create a vacuum inside the tube 3.
In one embodiment of the device as shown in
In the embodiment shown within
However, in the embodiment of
Making the cuff 4 integral with the tube 3 is, as described above and shown in
Although the device of the invention could be used for the extraction of various types of tissue it is preferably used to extract brain tissue from a dead animal such as a farm animal, most preferably a dead cow being assayed for the presence of prions. The device could readily be used for the extraction of brain tissue from any farm animal including cows, pigs, horses, sheep, goat or any animal including non-farm animals such as a deceased human or other primate.
Although the device of the invention could be produced in various sizes it is important that the size of the device be fairly close to the particularly preferred range as such allows for obtaining an adequate but not too large of a sample which can be readily assayed. Thus, the tube 3 preferably holds a volume of about 1 ml with the range preferably being 0.1 to 10 ml., more preferably 0.5 to 5 ml and most preferably graduated to show a measured volume of 1 ml with a very small (e.g. ±0.01 ml) volume of error. The inside diameter of the tube 3 should be approximately 3/16 of an inch (0.4 cm). The length of the tube “L” should be approximately three inches and the length “C” of the cuff 4 should be approximately 1/4 inch with about half of the cuff inserted into the tube 3 and half extending outside of the tube 3 with the cutting edge 13 of the cuff 4 extending outward.
The system of the invention comprises the device 2 as shown in any of
The breakable seal 23 is punctured by the sharp end 13 of the cuff 4 by the device 2 shown in any of
Each well of the 96 well plate preferably comprises a plurality of beads such as 2, 3, 4, 5 or 10 or more etc. small beads approximately 1 to 3 mm in diameter. The well may also have reagent materials such as proteinase K therein. Once all of the wells are filled the 96 well plate is shaken vigorously so that the beads aid in homogenizing the sample and mixing the reagent into the sample. When the sample has been sufficiently homogenized in all 96 wells the entire 96 well plate may be subjected to centrifugation. A more detailed description of the sample preparation is provided in the examples. After the sample is prepared the prepared sample is used in conducting an assay in order to determine if the sample is contaminated with prions. A more detailed description of the assay process is also provided in the examples.
In order to use a device of the invention it is first important to extract the brainstem of a cow. Such a brainstem 31 has been extracted and is shown in the gloved hand 30 of a researcher in
In order to extract the sample the brainstem 31 shown in
A sampling device 2 of a type as shown in
As shown in
After the device 2 is taken out of the brainstem the plunger should be pushed forward slowly until the plunger contacts the tissue sample present within the device. At this point the user should confirm that the end or black piece of the plunger is positioned at 0.3 to 0.35 ml marks on the 1 ml device. If there is too much tissue in the device it is possible for the user should push out tissue into a waste container until a proper measurement is achieved. If there is too little tissue in the device then the sample material may be extruded into a weighing device and reinserted into the same side of the brainstem where the process can be repeated in order to extract additional material with the syringe.
The sample should be dispensed into a tubular opening 23 as shown within the 96 well plate 21 of
In general a sample is prepared by concentrating prions within the sample. This is carried out by homogenizing the sample and mixing the sample with a complexing agent which selectively complexes with prions within the sample. The complexing agent may be a compound such as sodium phosphotungstate. Those skilled in the art will recognize a range possible complexing agents which include other salts of phosphotunstic acid, antibodies, and any agent which selectively binds to prions forming a complex which has a higher specific gravity as compared to the prion by itself. The complexing agent is mixed with the sample for a time sufficient to form complexes between the agent and the prions which might be present in the sample. After the mixing has been completed and sufficient time and conditions have occurred the sample is subjected to centrifugation and the complexing agent aids in increasing the specific gravity by binding to the prions. Thereafter the sample may be treated with a proteinase which selectively degrades the other proteins present within the sample, i.e. proteins other than prions. The treatment process may be eliminated in some circumstances and when used may be with proteinase K or other suitable protease or other agent which degrades other proteins present in the sample e.g., heat, pressure or agitation. This treatment may be carried out prior to, during or after centrifugation. A more detailed description of sample preparation is provided within U.S. Pat. No. 5,977,324 issued Nov. 2, 1999 incorporated here by reference to disclose and describe a sample preparation method.
Once the sample has been properly prepared individual samples within the individuals wells are then subjected to an assay method in order to determine if the prepared sample is contaminated with prions. This is carried out by extracting the sample and dividing the sample into a first portion and a second portion. The first portion of the sample is contacted with a labeled antibody such as an antibody disclosed within U.S. Pat. No. 6,537,548 issued Mar. 25, 2003 incorporated herein by reference to disclose and describe antibodies, labeled antibodies, and methods of using such. The antibody binds to PrP proteins in their non-disease confirmation with a higher degree of affinity than the antibody binds to PrP protein and its disease conformation.
The second portion of the treated sample is then subjected to further treatment. This treatment causes PrP protein in the second disease related conformation (prions) to assume a different conformation which conformation has a higher degree of binding affinity for the labeled antibody as compared with its affinity for PrP protein in the second disease conformation (prions). Thereafter, the treated second portion is brought into contact with a labeled antibody of the same type used in contacting the first portion of the sample.
The level of binding of labeled antibody to PrP protein in the first portion is determined as is the level of binding to the treated PrP protein in the second sample. A comparison of the level of binding of the labeled antibody to PrP protein in the first portion of the sample is then compared with the level of binding in the second portion. Thereby it is possible to determine if the sample comprised PrP protein in the second disease conformation, i.e. if the sample included any prions. In essence the assay is carried out by relaxing the constricted conformation of prions so that they bind to the antibody. If there are no prions present then there will be no constricted conformation to relax. Those skilled in the art will understand that the treatment of the second portion may cause some increase in signal even if no prions are present. However, this increase can be accounted for and appropriate adjustments made so as to not assume a positive result when no prions are present. A more detailed description of such an assay is provided within U.S. Pat. No. 5,891,641 issued Apr. 6, 1999 incorporated herein to disclose and describe this and other assay methods. However, other assays for the detection of prions could be used to test the samples prepared in accordance with the present invention.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to make and use the present invention, and are not intended to limit the scope of what the inventors regard as their invention nor are they intended to represent that the experiments below are all or the only experiments performed. Efforts have been made to ensure accuracy with respect to numbers used (e.g. amounts, temperature, etc.) but some experimental errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, molecular weight is weight average molecular weight, temperature is in degrees Centigrade, and pressure is at or near atmospheric.
A device 2 as shown in
As shown in the above examples the device 2 as shown in
A tissue extraction device 2 as shown in
This example can also be carried out without the use of the 96 well plate. As indicated above it is possible to use individual tubes such as 2 ml tubes which may include beads into which the sample is placed and shaken in order to bring about homogenization of the brain tissue.
The PrPc protein can be purified as described in Pan, Stahl et al. (1992) Protein Sci 1:1343-1352; Pan, Baldwin et al. (1993) Proc Natl Acad Sci USA 90:10962-10966. Protein content can be determined by the BCA method. The purity of PrPc protein, can be determined on SDS PAGE followed by silver staining and Western.
Standard Syrian hamster PrPSc can be purified from a standard pool of scrapie strain Sc237 infected hamster brains as described in Turk, Teplow et al. (1988) Eur J Biochem 176:21-30. The infectivity of this standard, as determined by an incubation time assay on Syrian hamsters after intracerebral inoculation, should be 107.3 ID50/ml and specific infectivity 108.2 ID50/mg of PrPSc protein. However, the specific infectivity may vary from lot to lot ±100.5 ID50/mg. The protein content can be determined by BCA assay using Bovine serum albumin as a standard. The preparation can be considered homogeneous with one major band on SDS PAGE after silver staining and Western Blots. The PrP proteins of the brain of other animals can be obtained in the same manner.
PrPSc is isolated from a fresh brain sample of a cow that exhibited symptoms of a neurological disorder consistent with the presence of PrPSc. Approximately 10 g of brain tissue is used to produce a homogenate. The brain tissue is flash-frozen in liquid nitrogen, and then homogenized using a standard mortar and pestle technique to dissociate the tissue for further extraction procedures. Phosphate buffered saline (PBS) pH 7.4 containing 4% (w/v) sodium dodecylsarcosinate (sarcosyl), an ionic surfactant, is added to the brain homogenate in a 1:5 (v/v) ratio to the brain homogenate. A solution of 4% sodium phosphotungstic acid (PTA) and 170 mM MgCl2, pH 7.4, is added to the buffered homogenate solution to a final concentration of 0.2% PTA. The sample is exposed to the PTA for 16 hours at 30° C. on a rocking platform. At the end of 16 hours, Proteinase K is added to the solution providing a final concentration of 25 μg/ml, and the sample is incubated for one additional hour at 37° C. The addition of proteinase K generally increases the efficiency of the precipitation of PrPSc, in part by degrading other remaining proteins including PrPc.
Following incubation, the sample is transferred to 1.5 ml sterile tubes, with approximately 1 ml aliquots of the PTA-homogenate solution per tube. The sample is centrifuged at 10,000 g in a table top centrifuge (Eppendorf) for 40 minutes at room temperature. The supernatant is decanted from the tubes, and each pellet is resuspended in sterile water to the desired overall protein concentration. Protease inhibitors are added to the solution: PMSF to a concentration 0.5 mM, Aprotinin to a final concentration of 2 mg/ml, and Leupeptin to a final concentration of 2 mg/ml. The protease inhibitors protect the sample from degradation under certain storage conditions. An aliquot of protein for current use is stored at 4° C. The remaining protein is aliquoted, and stored at −20° C.
The total protein content of the pellet is reduced 100 fold as compared to similar procedures known in the art. The PrPSc or PrP 27-30 content of this pellet represents approximately 40-60% of the total protein. This procedure thus results in a protein sample highly enriched in PrPSc protein species.
PrPSc is isolated from brain samples of a deceased individual suspected of being affected with a prion-based neurological disorder. Approximately 5 g of human brain tissue is used to produce a homogenate. The homogenate is produced using a dounce homogenizer to dissociated the tissue for protein extraction. A solution of 0.24 mM Triton-X, a non-ionic surfactant, in PBS pH 7.4 is added to a final 1:1 (v/v) ratio. A solution of 4% sodium phosphotungstic acid (PTA) and 170 mM MgCl2, pH 7.4, is added to the buffered homogenate solution to a final concentration of 0.3% PTA. The sample is exposed to the PTA for 8 hours at 37° C. on a rocking platform.
Following incubation, the sample is transferred to 2.0 ml sterile tubes, with approximately 1 ml aliquots of the PTA-homogenate solution per tube. The sample is centrifuged at 14,000 g in a table top centrifuge (Brinkmann) for 30 minutes at room temperature. The supernatant is decanted from the tubes, and each pellet is resuspended in a 25 μg/ml proteinase K solution. The tubes are incubated for one additional hour, rocking, at 37° C. The sample is again centrifuged at 14,000 g in a table top centrifuge for 30 minutes at room temperature. The supernatant is decanted, and the sample resuspended in 100 μl of sterilized water. Concentration can be determined using spectrophotometric techniques. The PrPSc or PrP 27-30 content of this pellet represents approximately 40-60% of the total protein.
A brain sample from a sheep exhibiting neurological disorders is isolated and homogenized using a Polytron automated homogenizer. Approximately 1 gram of protein is homogenized in this fashion. PBS pH 7.4 containing 1% (w/v) sodium dodecyl sulfate (SDS) is added to the brain homogenate in a 5:1 (v/v) ratio. A solution of 4% sodium phosphotungstic acid (PTA) and 170 mM MgCl2, pH 7.4, is added to the buffered homogenate solution to a final concentration of 0.25% PTA. The sample is exposed to the PTA for 1 hour at 45° C. on a rocking platform.
Following incubation, the sample is transferred to 1.5 ml sterile tubes, with approximately 1 ml aliquots of the PTA-homogenate solution per tube. The sample is centrifuged at 20,000 g in a table top centrifuge (Eppendorf) for 20 minutes at room temperature. The supernatant is decanted from the tubes, and each pellet is resuspended in sterile water to the desired overall protein concentration. An aliquot of protein for current use is stored at 4° C. The remaining protein is aliquoted, and stored at −20° C. The PrPSc or PrP 27-30 content of this pellet represents approximately 40-60% of the total protein.
The preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims.
