Chemical apparatus and process disinfecting – deodorizing – preser – Blood treating device for transfusible blood – Oxygenator
Reexamination Certificate
1999-02-23
2001-06-12
Alexander, Lyle A. (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Blood treating device for transfusible blood
Oxygenator
C422S105000, C422S067000
Reexamination Certificate
active
06245295
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
This invention relates generally to the field of biological sample testing apparatus and systems, and more particularly to the subject of test sample cards which have one or more wells for containing a fluid or test sample containing a microbiological agent or organism and a reagent, and in which the well is covered and isolated from the atmosphere by a transparent membrane or tape adhered to the test sample card body to form a closed reaction chamber.
B. Description of Related Art
A variety of test sample cards are described in the patent literature which have a well or reaction site for receiving a fluid sample containing a microbiological agent, such as a microorganism, and a reagent. Several representative patents include Meyer et al., U.S. Pat. No. 4,318,994, Charles et al., U.S. Pat. No. 4,116,775; Fadler et al., U.S. Pat. No. 4,038,151 and Charles et al., U.S. Pat. No. 4,118,280, the contents of each of which are fully incorporated by reference herein. These patents describe a test sample card having a plurality of wells arranged in the test sample card body. The reagent is typically loaded in the well of the card during the completion of manufacture of the card. The reagent typically comprises a growth medium for a microbiological agent in the fluid or test sample. It is known to load a different reagent in each of the wells of the card in order to perform identification testing of a fluid sample containing an unknown microbiological agent or organism. It is also known to include in the reagent various antibiotics in order to test the microbiological agent for susceptability to the antibiotics.
In the sample testing system described in the Charles et al '280 patent, after the well of the test sample card has been loaded with the fluid sample, the card is incubated for a period of time to promote a reaction between the microorganism and the reagent, i.e., growth of the microorganism. After a period of time, the well is subject to optical analysis by a transmittance light source and a detector which are positioned on opposite sides of the well or by alternate detection methods. If the growth medium or reagent is specifically suited for or “matches up” with the particular microorganism in the fluid sample, the population of the microorganism increases substantially, or some other predetermined reaction, i.e., chemical reaction, takes place, which results in the well turning cloudy and thus having a change in light transmission characteristics. The detector determines the amount of light that is transmitted from the source through the well. By comparing the transmittance measurement over a period of time, typically several hours at least, with an initial transmittance measurement, it is possible to determine whether in fact the reagent and microbiological agent are matched by virtue of the change in transmittance measurement reaching a threshold value, such as 25 or 30 percent. The change in light transmission characteristics therefore can be used to indicate the presence of a specific microorganism in the well. Identification and susceptibility may also be detected by absorbance measurements where a fluorescent agent is provided in the growth medium.
The test sample cards described in the above patents and used in the above process have a thin transparent membrane in the form of a tape adhered to the card body covering the wells, thereby separating the interior of the wells from the atmosphere. The tape serves to prevent the fluid sample from leaking from the wells card. The tape covers the well to prevent contaminants from entering the wells. The tape also servers as a transparent window through the well, enabling light from a light source to be transmitted through the well of the card and to impinge upon a suitable detector on the other side of the well.
Several materials have been used in the prior art for the membrane or tape used to cover the sample wells. These materials include polyfluorinated polymer films such as FEP (poly(tetrafluoroethylene-co-hexafluoropropylene)) and PFA (poly[tetrafluoroethylene-co-perfluoro(alkoxy vinyl ether)], polyethylene terepthalate or PET, commonly known as Mylar, and BOPP (biaxially oriented polypropylene). All of the above materials share a common property: they are relatively impermeable to gasses and water vapor. Such materials perform adequately in terms of their functions of sealing the well and providing a transparent barrier for the well. As a result, persons working in the art have directed their efforts at improving the sample testing process by designing improvements to the test sample cards and wells themselves, improving the quality of the reagents, and improving the design of the optical instrumentation and the illumination techniques. The design and characteristics of the specific material used to cover the wells of the test sample card has been given little attention in the prior art. Whereas the prior art failed to appreciate the role that the tape can perform in improving the test reaction process, we describe herein a test sample card construction having a polymethylpentene membrane covering the wells that can substantially reduce the time required to perform the testing of the fluid sample to identify the microorganism or to determine its susceptibility to a particular antibiotic.
SUMMARY OF THE INVENTION
The present inventors have discovered that the use of a transparent membrane made from polymethylpentene to cover the wells contributes surprisingly well to promotion of the reaction between the reagent and the microorganism, due to increased oxygen transmissibility and permeability properties of a polymethylpentene membrane, particularly when the membrane has a thickness of between 1 and about 8 mils. The promotion of the reaction between the reagent and the microorganism provided by the polymethylpentene membrane results in a substantially shortened amount of time required to incubate the test sample card and obtain the test results.
Polymethylpentene has an additional advantage over the prior art materials as a material for covering a sample well: cost. Since test sample cards are typically manufactured in very large numbers, reducing the cost of materials to manufacture a card can add up to a substantial savings.
It is accordingly an object of the invention to provide a test sample card which has a membrane covering the wells of the card to form a barrier between the fluid sample in the well and an atmosphere external of the well that promotes the reaction between a microorganism in a fluid sample introduced into the well and a reagent.
A further object of the invention is to provide a test sample card that has a membrane covering the wells of the card to form a barrier between the fluid sample in the well and an atmosphere external from the card, but which has superior oxygen permeability and transmissibility properties.
A further object of the invention is to provide a test sample card that can be manufactured at a reduced cost.
REFERENCES:
patent: 3963355 (1976-06-01), Aldridge, Jr. et al.
patent: 4038151 (1977-07-01), Fadler et al.
patent: 4116775 (1978-09-01), Charles et al.
patent: 4118280 (1978-10-01), Charles et al.
patent: 4318994 (1982-03-01), Meyer et al.
patent: 4883641 (1989-11-01), Wicks et al.
patent: 4952373 (1990-08-01), Sugarman et al.
patent: 5021294 (1991-06-01), Karasawa et al.
patent: 5219762 (1993-06-01), Katamine et al.
patent: 5364396 (1994-11-01), Robinson et al.
patent: 5364766 (1994-11-01), Mach et al.
patent: 5858770 (1999-01-01), Perlman
patent: 5863792 (1999-01-01), Tyndorf et al.
patent: 5869321 (1999-02-01), Franklin
patent: 62-144660 (1987-05-01), None
patent: 596690 (1993-04-01), None
patent: 6-219472 (1994-08-01), None
patent: WO9411489 (1994-05-01), None
Derwent Publications Database WPI Section Ch, Week 9320 Class A92, AN93-164008 XP002013177 & JP 05 096690 A (Dainippon Printing Co. Ltd.) Apr. 20, 1993.
L.C. Lopez et al., “Synthesis, Structure, and Properties of Poly (4-Methyl-1-pentene)”, J.M.S.-Rev.
Chen Patrick K.
O'Bear Raymond E.
Alexander Lyle A.
bio Merieux, Inc.
McDonnell & Boehnen Hulbert & Berghoff
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