Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
2000-12-27
2004-11-02
Alexander, Lyle A. (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S051000, C422S067000, C436S180000
Reexamination Certificate
active
06811753
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a blood testing tool used for a blood test.
2. Related Background Art
In a blood test, a sheet blood testing tool consumed per specimen is used for various purposes. Examples of this testing tool include those that retain blood, from which blood to be tested is extracted; and those that are pre-impregnated with a reagent or the like so that the blood and the reagent react with each other with the result being measured by an optical or electrochemical method, etc.
Such a blood testing tool has been used for various purposes in general clinical tests or the like. In addition, the suitability of such a blood testing tool has been studied for use in remote clinical testing systems. Indeed it is actually used in certain remote clinical testing systems. In such a remote clinical testing system, a patient collects blood by himself at home, and the blood testing tool is impregnated with the blood. This is then dried, and the blood testing tool is then mailed to a test institute such as a hospital for testing. The patient who mailed the blood can then be informed of the test result by a mail or by visiting the hospital.
When the test item is a component of blood plasma or blood serum such as blood glucose or the like, blood cells must be separated in the blood testing tool. Generally, in a conventional blood testing tool, a blood cell separator such as a glass filter or the like is incorporated into the blood testing tool. However, a blood testing tool having an asymmetric porous membrane with pores whose sizes vary in a thickness direction has been developed recently. When blood is supplied to the porous membrane from the side having larger pores, blood cells are separated. The blood penetrates in the thickness direction and thus blood plasma or blood serum comes out of the other side. An advantage of using a blood testing tool having a porous membrane is that the clogging of blood cells can be prevented.
However, such conventional blood testing tools have the disadvantage that only a small amount of blood plasma or blood serum can be collected. For instance, a collection rate of blood plasma or blood serum in conventional blood testing tools is about 25% at most. Therefore, when a trace component in the blood plasma or blood serum is to be analyzed, there is the possibility that the trace component cannot be analyzed correctly due to the small size of the sample obtained. Particularly, in the case of the remote clinical testing system, where a patient collects blood himself, there is the difficulty of obtaining a large enough blood sample. In addition, since there are many test items, an increased amount of blood plasma or blood serum must be collected.
SUMMARY OF THE INVENTION
The present invention at least in its preferred embodiments is intended to provide a blood testing tool that can separate blood cells easily and can collect blood plasma or blood serum with a high yield.
In order to achieve the above-mentioned object, a blood testing tool includes an asymmetric porous membrane with a pore size distribution in which an average pore size varies so that it is reduced continuously or discontinuously in a thickness direction, wherein the asymmetric porous membrane includes a blood supply portion, a development portion, and a blood-cell blocking portion formed between the blood supply portion and the development portion, pores in the blood-cell blocking portion include only pores through which blood cells cannot pass, the arrangement being such that when blood is supplied to the blood supply portion at a side having larger pores, the blood moves in a direction substantially parallel to a surface of the asymmetric porous membrane by capillary action, but only blood plasma or blood serum moves into the development portion.
As described above, the blood testing tool of the present invention allows blood to move in the porous membrane in the direction parallel to the surface (a transverse direction) and blood cells can be separated during the movement. This is different from the conventional case where blood moves in a thickness direction and can induce a strong capillary action. Thus a large amount of blood plasma or blood serum can be collected. In addition, a sufficient region for retaining blood plasma or blood serum reaching the region can be secured. According to the preferred form of the blood testing tool of the present invention, therefore, blood plasma or blood serum can be obtained with an excellent collection rate and blood cells also can be separated adequately. In the blood testing tool, the collection rate of blood plasma or blood serum may be, for example, about 60 to 70%. In the blood testing tool, since the blood supply portion and the development portion do not lie one on top of another, measurement can be carried out from any sides of the development portion, when the measurement is to be carried out directly with respect to the blood testing tool by an optical method (including visual observation). In the present invention, the “pores through which blood cells cannot pass” are not limited to the pores with smaller sizes than spherical diameters of blood cells, but may be pores through which blood cells eventually cannot pass regardless of the mechanism of preventing blood cells from passing through the pores. Therefore, the pores through which blood cells cannot pass may include pores larger than the spherical diameters of blood cells. In addition, the “average pore size varies so that it is reduced discontinuously” means that the average pore size may vary, for example, to be reduced in a stepwise manner.
Preferably, the blood testing tool further includes a groove formed between the blood supply portion and the development portion, wherein a portion between a bottom of the groove and a part of a surface of the asymmetric porous membrane corresponding to the bottom is the blood-cell blocking portion.
The groove may be formed by compression or cutting out of a part of the asymmetric porous membrane.
Preferably, pores in the development portion include only pores through which blood cells cannot pass. In this case, the development portion also may function as the blood-cell blocking portion.
Preferably, the pores in the blood-cell blocking portion have a pore size in a range of 1 to 50 &mgr;m, more preferably 5 to 30 &mgr;m, and particularly preferably 10 to 20 &mgr;m.
It also is preferable that in the asymmetric porous membrane, the maximum pore size is in a range of 30 to 300 &mgr;m and the minimum pore size is in a range of 1 to 30 &mgr;m.
Preferably, the asymmetric porous membrane has a single layer structure. The single layer structure preferably includes no interface (i.e. no contact surface between layers). Therefore, blood plasma or blood serum can move more easily than if an interface were present, and hemolysis or the like caused by contact between blood cells and an interface can be prevented.
Preferably, the asymmetric porous membrane is supported by a supporter. Accordingly, regardless of the strength of the porous membrane, a blood testing tool with a sufficient strength can be obtained, which enables easy handling.
Preferably, the asymmetric porous membrane is formed from at least one resin selected from polysulfone, polyamide, polyimide, polycarbonate, polystyrene, polyaryl hydrazide, and the like. More preferably, the porous membrane is formed of polysulfone.
Furthermore, it is preferable that the asymmetric porous membrane is treated to be provided with hydrophilicity. This allows blood to develop easily in the porous membrane.
Preferably, the development portion contains a stabilizing agent for maintaining stability of components in the blood plasma or the blood serum.
Preferably, the development portion contains an analytical reagent. Accordingly, blood plasma or blood serum separated in the blood testing tool is allowed to react with the analytical reagent without being collected from the blood testing tool, thus analysis may be conducted.
The blood
Hirao Konomu
Noda Yuichiro
Tanaka Yoshiyuki
Uchigaki Takatoshi
Alexander Lyle A.
Arkray Inc.
Merchant & Gould P.C.
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