Chemical apparatus and process disinfecting – deodorizing – preser – Control element responsive to a sensed operating condition
Reexamination Certificate
1999-02-11
2003-01-14
Alexander, Lyle A. (Department: 1743)
Chemical apparatus and process disinfecting, deodorizing, preser
Control element responsive to a sensed operating condition
C422S105000, C435S297100, C436S169000
Reexamination Certificate
active
06506346
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a diagnostic test container for the analysis of potentially infectious or toxic material.
BACKGROUND
The increased incidence of highly infectious diseases and chemical contamination poses two independent problems for the pathology services:
1. To safely detect these highly infectious diseases;
2. To safely carry out other tests on samples that may concurrently be infected or contaminated or are thought to be infected or contaminated.
The object of the present invention is to reduce the risks associated with these tests.
Existing Technology
It is known to use membranes to produce filtrates for chemical analysis. It is also known to retain infectious material in a test container by means of a bacteria-retaining membrane, as described for example in U.S. patent specification No. 4,421,849, which states that “the filter should have pores from 0.22 to 0.45 (microns) to ensure micro-organism impermeability”.
However it should be noted that such a membrane will not retain viruses; and that carrying out tests on material containing viruses without taking additional steps to retain them potentially exposes the tester to the viruses.
In our patent application No. PCT/GB91/00446, published under No. WO 91/14466, we described:
1. A method of testing a potentially infectious substance, from the group of blood- tissue- or other biological-substances, the method consisting in the steps of:
enclosing and sealing the substance to be tested in a closed container of which at least a part is formed of semi-permeable membrane, the semi-permeable membrane having a molecular weight cut-off such that viruses and other potentially infectious organisms are retained within the container by virtue of having a molecular weight higher than the molecular weight cut-off of the membrane, and
contacting the semi-permeable membrane with a test reagent having a molecular weight lower than the molecular weight cut-off of the membrane and allowing the test reagent to pass through the membrane and react with the substance.
2. A method of testing a potentially infectious substance, from the group of blood- tissue- or other biological-substances, the method consisting in the steps of:
enclosing and sealing the substance to be tested in a closed container of which at least a part is formed of semi-permeable membrane, the semi-permeable membrane having a molecular weight cut-off such that viruses and other potentially infectious organisms are retained within the container by virtue of having a molecular weight higher than the molecular weight cut-off of the membrane, and
contacting the semi-permeable membrane with a test reagent whereby substances on which tests are to be performed and which are of lower molecular weight than the molecular weight cut-off of the membrane can pass out of the container to react with the test reagents.
The difference between these two methods is that in the first the reagent passes into the closed container and reacts there; and in the second the testable substance passes out of the closed container for reaction. The mechanisms for movement of the reagent and testable substance are predominantly osmotically driven ultra-filtration and dialysis. The membrane is viral tight and provides a truly aseptic barrier.
The Invention
An object of the present invention is to enable these tests to be carried out in a self-contained manner.
According to the present invention we provide a container for testing a sample liable to include a potentially infectious, toxic or dangerous material, the container comprising:
one or more primary chambers for retaining potentially infectious, toxic or dangerous substances,
means for sealing a sample into the primary chamber(s),
one or more secondary chambers linked to the primary chamber(s) via at least one common wall(s) and a
a semi-permeable membrane incorporated in the common wall(s),
the semi-permeable membrane having a molecular weight/effective molecular diameter or configuration cut-off such that potentially infectious, toxic or dangerous material placed and sealed in the primary chamber(s) is retained there by virtue of having a molecular weight higher than the molecular weight cut-off of the membrane.
With such a container potentially infectious, toxic or dangerous material of higher molecular weight or effective molecular diameter than the membrane's cut-off remain sealed within the primary chamber(s). Hereinafter, the term “molecular size” in the context of the membrane's cut-off will mean that the molecular weight or effective molecular diameter or configuration (i.e. effective minimum cross-sectional shape inhibiting passage through the membrane) is such that the substance concerned will not pass through the membrane because it is too large for the pore size of the membrane.
Many types of test or assay can be carried out on material in or released from the sample in the primary chamber(s) but it is envisaged that most uses of the containers of the invention will be either of the two following:
a) Those where test reagent(s) in the secondary chamber(s) having a lower molecular size than the cut-off of the membrane pass through the membrane(s) and react with material retained within the primary chamber(s). For instance, these include assays such as the direct detection of viral bodies or the determination of blood groups. In containers for these the membrane is selected to allow through relatively large proteins but completely block the movement of viral particles;
b) Those where a lower molecular size fraction from the primary chamber(s) passes into the secondary chambers for reaction with reagents therein.
The simplest embodiment of the invention will be a container having two chambers separated from each other by a single semi-permeable membrane, the material to be assayed being placed and sealed in the primary chamber and reagents being placed in the secondary chamber
As used hereinafter, the term the “sample” means the potentially infectious, toxic or dangerous material that is placed and then sealed within the primary chamber(s). It can be any biological material which is dead or alive, intact or in parts. It could come from any animal or plant species or microorganism including, but not restricted to, bacteria, viruses, fungal and other botanical material as well as prions. Most commonly, but not exclusively, these samples will blood and related fluids, urine samples, faecal samples (solid or liquid), cells, tissues or organs or exudates. The material of biological origin may constitute all or part of the specimen including live specimens. The dangerous component of this material will vary in effective molecular size, and the semi-permeable membrane will be chosen to have an appropriate cut-off to ensure that the dangerous component cannot pass through the membrane and will be retained in the primary chamber(s).
Choice of the semi-permeable membrane is critical not only for retaining the potentially infectious, toxic or dangerous fraction (hereinafter called the “dangerous fraction”) of the sample within the primary chamber(s), but also for allowing passage of relatively safe fractions from the sample and/or reagents to it. Thus the membrane's cut-off must not only be low enough to prevent passage of the dangerous fraction but also be high enough to facilitate maximum movement of these fractions and reagents.
Membranes are now readily available with a wide range of molecular porosities and varying physical properties including physical strength, chemical structure and physical form and it is possible to select a membrane with a porosity that ranges from a few hundred to many million Daltons and beyond that to any macro-porosity. Materials that are used for membranes include cellulose film, PTFE, polyurethane acrylic copolymers, cellulose acetate, polyalginate, polysulfone, polyvinyl alcohols, polyvinylidene fluoride, polyacryl nitriles and derivatives and mixtures of these.
The following table gives the molecular size range (in microns) of various ranges of substances, and examples
Alexander Lyle A.
Hampshire Advisory and Technical Services Limited
Wolf Greenfield & Sacks P.C.
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