Abstract: A filtration device, apparatus, and method of filtration useful for filtering liquid samples are disclosed wherein filtration occurs opposite the direction of centrifugal force. The filtration device is placed within a container that contains the liquid sample to be filtered. Together, the filtration device and the container comprise the filtration apparatus. Centrifugation forces the liquid sample present in the container to enter the filtration device, thereby effecting filtration. The vertical position of the filtration device is fixed within this container during filtration.

Abstract: Devices for use in heterogeneous ligand-receptor assays, having a porous member in contact with a nonabsorbent textured surface, where the surface texturing is such that a capillary network is formed when in fluid communication with the porous member. More particularly, these devices comprise: (a) a porous member having (i) at least one binding agent capable of immobilizing at least one target ligand on the porous member from a fluid sample in at least one zone and (ii) a means for detecting the presence or amount of said target ligand as a result of the assay process; and (b) a nonabsorbent member in fluid communication with the porous member, the nonabsorbent member forming at least one capillary with the porous member so that when sample, alone or in combination with other fluids, is added to the porous member, fluid is drawn through the porous member.

Abstract: This invention provides methods, reagents, and kits that are useful for diagnosing infection by E. histolytica. The methods are based on the discovery of binding agents, including recombinant polyclonal antibodies, that bind to the 29 kDa antigen of E. histolytica.

Abstract: This invention provides methods, reagents, and kits that are useful for diagnosing infection by E. histolytica. The methods are based on the discovery of binding agents, including recombinant polyclonal antibodies, that bind to the 29 kDa antigen of E. histolytica.

Abstract: Methods and test devices for detecting the presence or amount of target ligand in non-competitive sandwich ligand-receptor assay processes. Antibodies which bind to the complex of ligand receptor and target ligand but do not bind significantly to the ligand receptor and which bind the target ligand with substantially less affinity than the complex are taught and their uses described. These assays can be used to eliminate the "hook" effect in non-competitive sandwich assays. Furthermore, the antibodies are selected and assay methods described so that, as a result of the assay process, no detectable response is observed due to the binding of antibody and ligand receptor in the absence of target ligand.

Abstract: This invention provides methods, compositions, and kits for detecting the presence of toxigenic strains of C. difficile in a biological sample. One embodiment provides methods for C. difficile detection that involve assaying for both C. difficile glutamate dehydrogenase and C. difficile toxin A or toxin B. In another embodiment, the invention provides a highly sensitive assay for C. difficile toxin A that is useful for determining whether a C. difficile strain is toxigenic. This embodiment involves binding of toxin A to a moiety that reversibly binds to a capture moiety present on a magnetic bead. A magnetic field is applied to the sample to concentrate the toxin A, after which the magnetic beads are dissociated and removed from the solution to obtain a highly concentrated preparation of toxin A, thus making possible a very sensitive assay.

Abstract: Assay methods for performing non-competitive ligand-receptor assays, where said assays provide a sensible result when the target ligand identified by the assay is present at a concentration greater than a defined threshold concentration. The threshold concentration can be selected to be the upper limit of a normal range of values for a target ligand in a sample, so that an assay in accordance with the invention provides a sensible result only when the target ligand is present at elevated levels.

Abstract: Devices for use in heterogeneous ligand-receptor assays, having a porous member in contact with a nonabsorbent textured surface, where the surface texturing is such that a capillary network is formed when in fluid communication with the porous member. More particularly, these devices comprise:(a) a porous member having (i) at least one binding agent capable of immobilizing at least one target ligand on the porous member from a fluid sample in at least one zone and (ii) a means for detecting the presence or amount of said target ligand as a result of the assay process; and(b) a nonabsorbent member in fluid communication with the porous member, the nonabsorbent member forming at least one capillary with the porous member so that when sample, alone or in combination with other fluids, is added to the porous member, fluid is drawn through the porous member.

Abstract: An immunoassay is provided which is selective for an analyte over immunologically related substances which may be present in a sample to be tested. The presence of the analyte is detected using a first binding substance, typically an antibody, in the presence of a second binding substance, typically another antibody. The first binding substance recognizes an epitope which is characteristic of the analyte and cross-reacts with a related epitope on the cross-binding substance. The second binding substance preferentially binds the common epitope on the cross-binding substance, thus reducing non-specific binding of the first binding substance.

Abstract: Novel conjugates and competitive and non-competitive assays for simultaneously detecting the presence or amount of at least two target ligands capable of competing with a single conjugate for binding to at least two different ligand receptors. The invention teaches and claims binding domains coupled to a signal development element to form a conjugate where each binding domain comprises at least one ligand analogue or ligand receptor depending on assay design. The binding domains are constructed such that they function independently from one another in assays for their respective target ligands. Each binding domain may bind its respective binding partners in the assay without affecting the binding reactions of other binding domains coupled to the same signal development element.

Abstract: This invention is directed to a ligand-receptor assay for determining the presence of at least one target ligand, capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a colloidal gold particle, in a fluid sample suspected of containing said target ligand comprising the steps of:a. contacting said fluid sample with said ligand analogue conjugate and said ligand receptor to form a homogeneous reaction mixture, the relative amounts of said ligand analogue conjugate and said ligand receptor being selected such that in the absence of said target ligand and subsequent to substantially equilibrium binding in said reaction mixture, substantially all of said ligand analogue conjugate is bound to said ligand receptor such that no unbound ligand analogue conjugate is detected as a result of the assay method;b.

Abstract: Assay for detecting the amount or presence of target ligand in a sample. The assay includes a ligand analogue conjugate having a linkage site and a binding site, a ligand receptor, and a sample. The assay includes the steps of providing at least one crosstalk inhibitor. This inhibitor, under assay conditions, competes with the linkage site of the ligand analogue conjugate for binding to the ligand receptor, and does not compete with the binding site of the ligand analogue conjugate for binding to the ligand receptor. In the invention, the assay is performed for the target ligand in the presence of a sufficient amount of the crosstalk inhibitor to reduce the amount of binding of the linkage site of the ligand analogue conjugate to the ligand receptor. The invention also features a method for identifying crosstalk inhibitors, and the crosstalk inhibitors themselves.

Abstract: Methods and test devices for detecting the presence or amount of target ligand in non-competitive sandwich ligand-receptor assay processes. Antibodies which bind to the complex of ligand receptor and target ligand but do not bind significantly to the ligand receptor and which bind the target ligand with substantially less affinity than the complex are taught and their uses described. These assays can be used to eliminate the "hook" effect in non-competitive sandwich assays. Furthermore, the antibodies are selected and assay methods described so that, as a result of the assay process, no detectable response is observed due to the binding of antibody and ligand receptor in the absence of target ligand.

Abstract: Means for the detection of free ligand analogue conjugate in fluids from competitive ligand-receptor assay processes. Ligand analogue antibodies that bind the ligand analogue conjugate with substantially greater affinity than their affinity for target ligand are selected and used in competitive ligand-receptor assay processes to bind the free fraction of the ligand analogue conjugate. This means permits the detection of the free fraction of ligand analogue conjugate even in the presence of substantially higher concentrations of free target ligand. For the purposes of the present invention, ligand analogue antibodies are antibodies that exhibit at least 100.times.greater affinity for the ligand analogue conjugate compared to their affinity for the target ligand.

Abstract: This invention is directed to a ligand-receptor assay for determining the presence or amount of at least one target ligand, capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:a. contacting said fluid sample with ligand analogue conjugate and ligand receptor to form a reaction mixture, the relative amounts of ligand analogue conjugate and ligand receptor being such that in the absence of target ligand, and subsequent to substantially equilibrium binding, substantially all of the ligand analogue conjugate is bound to ligand receptor;b. detecting the unbound ligand analogue conjugate;c. relating the detectable signal to the presence or amount of target ligand in the fluid sample.

Abstract: This invention is directed to a ligand-receptor assay for determining the presence or amount of at least one target ligand, capable of competing with a ligand analogue conjugate for binding sites available on a ligand receptor, said ligand analogue conjugate comprising at least one ligand analogue coupled to a signal development element capable of emitting a detectable signal, in a fluid sample suspected of containing said target ligand, comprising the steps of:a. contacting said fluid sample with ligand analogue conjugate and ligand receptor to form a reaction mixture, the relative amounts of ligand analogue conjugate and ligand receptor being such that in the absence of target ligand, and subsequent to substantially equilibrium binding, substantially all of the ligand analogue conjugate is bound to ligand receptor;b. detecting the unbound ligand analogue conjugate;c. relating the detectable signal to the presence or amount of target ligand in the fluid sample.

Abstract: Disclosed herein is an apparatus and process for conducting ligand receptor assays. The apparatus comprises a first member which is a membrane or a filter to which is bound a receptor for the ligand or which is capable of extracting cells carrying the ligand from a fluid sample. The apparatus further comprises a second member which is composed of absorbent material which acts when in contact with the first member to induce flow through the first member when a fluid sample is added to it. The apparatus is used to conduct assays by applying a sample to the upper surface of the first member to bind ligand in the sample by means of receptor fixed to the first member or, in certain cases, by extracting cellular material which has ligand associated with it. Addition of the sample is typically followed by addition of labeled antibody against the antigen being assayed followed by a washing step to remove unbound labeled receptor.

Abstract: Disclosed herein is an apparatus and process for conducting immunoassays. The apparatus comprises a first member which is a membrane or a filter to which is bound an antibody, typically a monoclonal antibody, or which is capable of extracting cells from a fluid sample. The apparatus further comprises a second member which is composed of absorbent material which acts when in contact with the first member to induce flow through the first member when a fluid sample is added to it. The apparatus is used to conduct immunoassays by applying a sample to the upper surface of the first member to bind antigen in the sample by means of antibody fixed to the first member or, in certain cases, by extracting cellular material which has antigen associated with it. Addition of the sample is followed by addition of labeled antibody against the antigen being assayed followed by a washing step to remove unbound labeled antibody.