Abstract: A competitive assay for the concentration of a cyclic nucleotide such as cyclic adenosine monophosphate combines, in a reaction chamber provided with a capture antibody, an antibody for the cAMP or other cyclic nucleotide, the sample to be assayed and a conjugate of cAMP and alkaline phosphatase. The mixture is incubated and washed, and after washing, a 1,2-dioxetane which is caused to decompose when contacted by the alkaline phosphatase of said conjugate is added. The light emission caused by decomposition is measured, with the strength of the signal being inversely related to the concentration of the cyclic nucleotide. Optionally, an enhancement agent in the form of a polymeric onium salt may be added, to further enhance the light emission.

Abstract: Thrombotic or thromboembolic disease is detected or monitored by determining the presence or amount B in a urine sample.

Abstract: An isolated B1 domain polypeptide of bacterial Protein G which binds a Fab fragment of an IgG but substantially does not bind a Fc fragment of an IgG. Methods for the detection and purification of IgG Fc antibody fragments and Fab antibody fragments using the isolated GB1 domain polypeptides are also disclosed.

Abstract: Discoveries are disclosed that show particular aspects of recombinant DNA technology can be used successfully to produce a hitherto unknown type of human Platelet-Derived Growth Factor (PDGF) receptor protein free of other PDGF receptors. These proteins can be produced from DNA segments in cells in various functional forms. These forms variously enable biochemical and functional studies of these novel receptors as well as production of antibodies. Means are described for determining the level of expression of genes for specific types of PDGF receptor proteins, for example, by measuring mRNA in cells with PDGF receptor type-specific DNA probes or by measuring antigen in biological samples with type-specific antibodies.

Abstract: Disclosed herein are methods for the chemiluminescent assay of a variety of analytes of interest. The methods are adaptable to the determination of microbial species in both liquid samples and on solid surfaces. The disclosed methods can be used with rapid, self-contained chemiluminescence assay devices, or can be used with novel sampling devices and conventional microbial analysis techniques involving growth of microbial samples on appropriate culturing media. The specificity of the methods can be enhanced with the use of immunospecific reagents. The sensitivity of the technique can be increased by 3 to 6 orders of magnitude by first converting all DNA in the sample to inorganic phosphates before generating the emission signal. The breadth of applicability of the disclosed methods can be enhanced through the selection of appropriate enzyme-catalyzed reactions where one of the products of enzymatic oxidation is hydrogen peroxide.

Abstract: The present invention relates to the use of these cyclophilins, hereinafter referred to as ‘tyrosine-containing’ cyclophilins, in a method for identifying compounds capable of binding to and/or inhibiting the enzymatic activity of these proteins. Such compounds may be further screened for their ability to inhibit parasites which are not susceptible to the anti-parasitic effects of CsA.

Abstract: The invention relates to antibodies against VASP (vasodilator-stimulated phosphoprotein) which only bind VASP as an antigen when VASP is present in phosphorylated form, to hybridoma cells for their preparation, and to the use of the antibodies or antibody fragments as diagnostic agents and/or therapeutic agents.

Abstract: The invention concerns a method for the determination of antigen-specific antibodies of the immunoglobulin G class in the presence of immunoglobulins of the M class in body fluids by incubation with at least two different receptors R1 and R2 and optionally additional receptors, an essential component of R2 being a binding partner in monomeric form, a reagent for determining an antigen-specific antibody of the immunoglobulin G class as well as the use of binding partners in monomeric form for the determination of an antigen-specific antibody of the immunoglobulin G class.

Abstract: An immunochemical method for the determination of antibodies which are specific for an antigen and are of one of the immunoglobulin classes: A, M, D or E in a fluid, with this fluid being contacted with a solid phase to which the antibodies against this immunoglobulin class, or a fragment of an antibody of this type, are bound, which results in the immunoglobulin of this class being bound to this solid phase, and this solid phase being contacted with the antigen, which carries a labeling means where appropriate, and with a labeled antibody or a labeled fragment of an antibody against the antigen if the antigen is unlabeled and determination, from the amount of labeling means which is bound to the solid phase, of the amount of these antibodies which are specific for an antigen and are one of the immunoglobulin classes, which comprises the solid phase being simultaneously in contact with the fluid containing the antibody which is to be determined and with the antigen, which is labeled where appropriate, there b

Abstract: The invention concerns a method for isolating a target biological material contained in a sample, which consists in providing a capture phase comprising an organic molecule having at least a reactive function and at least a protein material capable of recognizing or binding, specifically and directly or indirectly, with the target biological material, said protein material having a specific covalent binding site with the organic molecule reactive function, consisting of at least a tag comprising at least six contiguous lysine, or lysine derivative residues, the method consists in contacting said target biological material with at least the capture phase; and detecting the target biological material fixed on the capture phase: The invention also concerns the capture and detection phases, and a reagent containing them.

Abstract: A monitor having a hollow semipermeable casing with a test strip is agitated in a sample volume of suspect liquid. The monitor is partially filled with tiny colored beads confined to its interior by the size of the openings in the semipermeable structure. Adhered to the beads are antibodies matched to the antigen characterizing the suspect substance. The test strip is segregated into collection and control regions. Antibodies matched to the suspect antigen are adhered only to the collection region. If the sample fluid contains the suspect substance, it will bind to both the bead antibodies and the collector antibodies, resulting in an accumulation of colored beads in the collection region but not the control region. A significant color differential between the two is a positive indication of the suspect substance. This invention has significant potential in screening for the date rape drugs, GHB and rohypnol.

Abstract: The present invention provides methods of identifying hot-spot residues for one or both members of a receptor-ligand complex of interest. Further provided are methods of using receptor hot-spot residues to identify compounds that functionally bind a receptor in a manner that mimics the binding of a known ligand for the receptor.

Abstract: A method of assaying for an analyte including the steps of: (i) passing a sample suspected of containing an analyte and reagents comprising a target ligand-analyte receptor conjugate and a detectable tracer containing a label for the analyte through filter apparatus containing a plurality of discrete flow zones wherein at least one zone functions as a capture zone having bonded thereto a receptor ligand for said target ligand; (ii) allowing the sample and accompanying reagents to incubate prior to passage through said at least one zone to facilitate formation of complex(es) of said conjugate and said at least one analyte in a liquid or fluid phase; and (iii) detecting the presence of analyte in the sample by activation of the label in said at least one zone after binding of the complex(es) conjugate to the associated receptor ligand(s).

Abstract: A method for the direct analysis of analyte in keratinized structures, e.g., hair, fingernails and toenails, which comprises preparing a mixture containing a low redox potential compound such as dithiothreitol or dithioerythritol, an enzyme suitable for the degradation of the keratin structure and a sample of the keratin structure; permitting the enzyme to at least substantially degrade the sample of keratin structure, filtering the digest solution to remove substances which may interfere with ligand based analytical methods and subjecting the filtered digest solution to analysis to determine the identity and amount of analyte in the keratin substance sample. To accelerate the method, cupric sulfate may be added to the mixture after degradation of the keratin sample. The enzyme may be a peptidase, endopeptidase or proteinase, with papain, chymopapain, and proteinase K being preferred for use in the invention.

Abstract: A method of producing a diagnostic or therapeutic conjugate of a protein, polypeptide or peptide containing at least one disulfide bond which is necessary to maintain its biological activity, and bearing at least one thiol-containing moiety linked thereto through a hydrazone or hydrazine linkage, is effected by contacting said protein, polypeptide or peptide with a thiol-reactive diagnostic or therapeutic agent, either preformed or generated in situ, to form a stable diagnostic or therapeutic conjugate of the protein, polypeptide or peptide without substantial cleavage of the disulfide bond. Diagnostic and therapeutic conjugates produced using the foregoing method, as well as kits for carrying out the method are provided.

Abstract: The present invention relates to a treatment for myocardial infarction and blood clots within a patient, and more specifically to a therapy which enhances clot lysis comprising administering to a patient an antibody directed to &agr;2-antiplasmin crosslinked to fibrin (&agr;2AP-FX) which does not inhibit plasma &agr;2-antiplasmin (&agr;2AP). The invention also relates to a treatment for enhancing clot lysis comprising administering an antibody directed toward &agr;2-antiplasmin crosslinked to fibrin which does not inhibit plasma &agr;2AP together with a thrombolytic agent.

Abstract: A novel method for examining bacterial growth state is carried out by measuring the levels of conserved cytosolic proteins specific for alternative growth states, using bacterial specific antibody fluorochrome-coupled probe. Utilizing the method of the invention, the cellular growth state of individual bacteria can be determined by measuring the abundance of growth state-specific protein homologs. For example, through use of the protein profiling method of the invention, bacterial VNC state can be distinguished by differentiating growing (exponential phase) from nongrowing or dormant (stationary phase) cells.

Abstract: The present invention provides an analyte detection device. The device comprises first and second zones, means to allow addition of a probe to the first zone, means to allow addition of a sample suspected to contain an analyte and means to allow passage of the probe from the first zone to the second zone. The first zone contains ligands reactive with the analyte and the second zone includes a membrane the impedance of which is dependent on the presence or absence of the probe and means to measure the impedance of the membrane. It is preferred that the probe includes an ionophore, preferably gramicidin. The present invention also relates to methods of detecting the presence of an analyte.

Abstract: Methods are described for conjugating radioiodinated peptides or carbohydrate structures to proteins with improved yields and qualities of conjugates. In one method, specially designed radioiodinated bifunctional peptides containing nonmetabolizable amide bonds are coupled to antibodies. In a second method, radioiodinated nonmetabolizable bifunctional peptides, which also contain aminopolycarboxylates, are coupled to antibodies. In a third method, radioiodinated bifunctional aminopolycarboxylates are coupled to antibodies. In a fourth method, a hydrazide-appended antibody is coupled to a radioiodinated carbohydrate or a thiolated antibody is coupled to a hydrazide-appended and radioiodinated carbohydrate. In a fifth method a monoderivatized cyanuric chloride is used to conjugate thiolated antibody. Radioiodinated residualizing antibody conjugates made by these methods are particularly stable in vivo and are suitable for radioimmunodetection and radioimmunotherapy.

Abstract: The full amino acid and DNA sequences of placental protein 13 (PP13) are disclosed. Also described are various PP13 derived peptide fragments, and a recombinant method for the production of PP13. PP13 may be used in a screening and a diagnostic method for pregnancy-related complications.

Abstract: A method of treating cancer in a patient deficient in p53 tumor suppression gene is described herein by administering to a patient a therapeutically effective amount if a polyamine such as DENSPM in combination with an anticancer agent. Also described is a method of selecting patients for cancer treatment with a polyamine, for example, DENSPM.

Abstract: Electrochemiluminescent-labels and enzyme substrates, which preferably are conjugated, are used in immunoassays and electrochemiluminescence is generated catalytically. In conventional electrochemiluminescence immunoassays, an anti-analyte antibody molecule can give rise to typically 6-8 electrochemiluminescence-active ruthenium atoms, while in the present invention, each enzyme-labeled anti-analyte molecule can give rise to thousands of electrochemiluminescence-active ruthenium atoms per second. An exemplary immunoassay is based on a catalytic process employing &bgr;-lactamase-conjugated anti-analytes which enzymatically hydrolyze electrochemiluminescent-labeled substrates, making them strongly electrochemiluminescent. The electrochemiluminescence signal generated by each anti-analyte molecule (i.e., each analyte molecule) is much greater than with the conventional method. Accordingly, greater sensitivity can be gained in the measurement of low concentrations of a given immunoassay analyte.

Abstract: Bis-maleimido cross-linking reagents join labelled antibodies having at least one sulphide interchain bridge. The conjugates have an enhanced binding capacity and have good blood clearance in vivo. The conjugates are of use in the diagnosis and therapy of tumors and may be prepared by reaction of the cross-linking reagent with the antibody.

Abstract: This invention provides a method of inhibiting HCV infection of a cell susceptible to HCV infection which comprises contacting the cell with an amount of a compound effective to inhibit binding of an HCV envelope glycoprotein to a DC-SIGN protein present on the surface of the cell, so as to thereby inhibit HCV infection of the cell susceptible to HCV infection. This invention provides a method of inhibiting HCV infection of a cell susceptible to HCV infection which comprises contacting the cell with an amount of a compound effective to inhibit binding of an HCV envelope glycoprotein to a DC-SIGNR protein present on the surface of the cell, so as to thereby inhibit HCV infection of the cell susceptible to HCV infection.

Abstract: The invention concerns a method for the determination of antigen-specific antibodies of the immunoglobulin M class in the presence of immunoglobulins of the G class and/or rheumatoid factors in body fluids by incubation with at least two different receptors R1 and R2 and optionally additional receptors wherein an essential component of R2 is a binding partner in a polymeric form and interference by IgG antibodies of the same antigen specificity is reduced by binding partners in a monomeric form; a reagent for determining an antigen-specific antibody of the immunoglobulin M class, as well as the use of binding partners in a monomeric form to reduce interference by IgG antibodies in the determination of antigen-specific IgM antibodies.

Abstract: This invention provides a method for measuring an antigen concentration in a sample, which comprises: preparing VH-domain polypeptide and VL-domain polypeptide of an antibody specific to the antigen; labeling one of the polypeptides with a reporter molecule to form labeled polypeptides, and immobilizing the other polypeptide onto solid-phase to form immobilized polypeptides; contacting the antigen-containing sample and the labeled polypeptides with the solid-phase; and measuring the reporter molecule of the labeled polypeptides bound to the immobilized polypeptides. The present invention permits simpler and quicker sandwich ELISA for measurements of an antigen concentration in high sensitivity.

Abstract: The INK4A (MTS1, CDKN2) gene encodes a specific inhibitor (InK4a-p16) of the cyclin D-dependent kinases CDK4 and CDK6. InK4a-p16 can block these kinase from phosphorylating the retinoblastoma protein (pRb), preventing exit from the G1 phase of the cell cycle. Deletions and mutations involving the gene encoding InK4a-p16, INK4A, occur frequently in cancer cells, implying that INK4a-p16, like pRb, suppresses tumor formulation. However, a completely unrelated protein (ARF-p19) arises in major part from an alternative reading frame of the mouse INK4A gene. Expression of an ARF-p19 cDNA (SEQ ID NO:1) in rodent fibroblasts induces both G1 and G2 phase arrest.

Abstract: Isolated antibody or preparation of antibodies comprising an antigen-binding domain wherein the antigen is present on activated dendritic cells and wherein the antibody does not interact with CMRF-44 antigen or CD83 antigen.

Abstract: The present invention relates to cells which have improved receptivity to viruses which are capable of infecting them. Receptivity to such viruses is improved by selecting cells from a population which express the receptor(s) that enable a virus to attach to the cell and gain entry into it. Any combination of viruses and host cell lines can be used. In a preferred embodiment, the present invention relates to improving receptivity or infectivity of a cell line which can be infected with an immunodeficiency virus, such as HIV-1.

Abstract: The present invention relates generally to a structure, on the surface of the support material of which structure molecular layers are immobilized so as to be electrically addressable, a method for the electrically addressable immobilization of molecules, a device for carrying out this method, and the use of this structure as a chemo- and/or biosensor, in particular as a multisensor system for chemical, biological, and physical assays, and for applications in the combinatorial synthesis on the boundary surface.

Abstract: The invention relates to a method for detecting in a body fluid sample at least one blood coagulation activity marker that reflects e blood coagulation activity of an individual. By correlating the amount or concentration of the blood coagulation activity marker present e.g. in a urine sample, it is possible to monitor the blood coagulation activity of a patient following surgery without having to obtain a blood sample from said patient.

Abstract: Invention performs an assay to determine presence or quantity of specific analyte in fluid sample. Representative device has two separate flow paths established sequentially in device with a single user activation step. First flow path delivers sample, and conjugate soluble binding reagents to solid phase. If analyte is present, an analyte:conjugate complex is formed and immobilized. Sample volume delivered by first path determined by absorbent capacity of solid phase, and not by amount of sample added to device. User need not measure sample volume. Sample/conjugate mixture is prevented from entering second flow path because capillary and surface energy of second flow path prevent it from being wetted by this mixture. Second flow path allows wash reagent to remove unbound conjugate and sample from solid phase to the absorbant, and optionally deliver detection reagents.

Abstract: A bacteriophage linked to an enzyme can replace an antibody in a system for detecting the presence of a bacteria in a sample. Specifically Brucella abortus (a pathogen which causes brucellosis in cattle) can be detected using Brucella bacteriophage for the virus, urease for the enzyme linked to the bacteriophage, m-maleimidobenzoyl-N-hydrosysuccimide ester as a coupling reagent, sera from mice immunized with Brucella bacteriophage for a detector antibody, urease conjugated to anti-mouse sheep antibody for an indicator, and urea with bromcresol purple as the substrate. The materials can be used in indirect (sandwich) or direct enzyme-linked viral assays (ELVirA).

Abstract: The invention provides methods and compositions relating to activated Sgk and the association of activated Sgk activity with proliferating cells, including methods for inhibiting the growth of an undesirably proliferating cell by contacting the cell with a specific inhibitor of activated Sgk whereby the amount of activated Sgk activity in the cell is reduced. Specific inhibitors are disclosed, including dominant negative mutants of activated Sgk, an Sgk mutant or fragment thereof comprising an unphosphorylatable residue corresponding to Thr 256 of native Sgk, and an active Sgk-specific antibody or antibody fragment, especially intrabody, etc. A wide variety of methods may be used to contact the target cell with the inhibitor, especially introducing into the cell a polynucleotide encoding the inhibitor under conditions whereby the inhibitor is expressed in the cell.

Abstract: A method and apparatus for urine self testing wherein the apparatus is placed directly into the toilet after urination which avoids the direct placement and retention of an apparatus in the stream of urine as is common with urine testing devices. The apparatus detects the presence of certain chemicals in dilute urine such as the presence of human chorionic gonadotropin (hCG) in the urine of a pregnant woman. An opening in the apparatus is fitted with a fluid absorption device which acts to concentrate the diluted urine on an indicator strip which contains antibodies, enzymes and antibody blockers which will provide a reactive change, usually of color, when subjected to a predetermined chemical such as hCG. The apparatus functions in dilute urine when placed in a toilet after urination and is largely constructed of biodegradable materials so that it can be flushed into the sewage system or a septic tank.

Abstract: The present invention is directed to a method of prognosticating the illness development of patients with carcinoma of the breast and/or for diagnosing carcinoma of the breast, the method comprising a qualitative determination of T1 protein and/or T1-mRNA in a sample material obtained from the patient. The invention further pertains to kits for performing the methods according to the invention.

Abstract: Growth differentiation factor-3 (GDF-3) is disclosed along with its polynucleotide sequence and amino acid sequence. Also disclosed are diagnostic and therapeutic methods of using the GDF-3 polypeptide and polynucleotide sequences.

Abstract: Ligand-aminodextran-(phycobiliprotein or tandem dye) conjugates useful for detection of a desired target biological material by providing an enhanced fluorescent signal are described. Also described is a method for a single-measurement quantification of multiple populations of cells based upon the labeling of different pairs of cell populations, each pair containing mutually exclusive cell receptors which are expressed at substantially similar receptor densities with labeled ligands for each receptor. One cell population is labeled with a ligand capable of binding to a first cell surface receptor which ligand is directly conjugated to a fluorescent phycobiliprotein or tandem dye; and a second cell population is labeled with a ligand capable of binding to a second cell surface receptor, which ligand is cross-linked to an aminodextran to a fluorescent phycobiliprotein or tandem dye.

Abstract: The present invention provides the RSP-1 and RSP-2 proteins which are involved in the cytoadhesion of P. falciparum during ring-stage infection of erythrocytes, antibodies which bind to the proteins, methods of screening for a P. falciparum infection, methods of determining the infective stage of P. falciparum and vaccines for protecting individuals from Plasmodium sp. infections.

Abstract: One end of a thin-tube type solid phase in which a receptor specific for a material or an organism to be measured which can induce a pH-change of substrate solution is immobilized is soaked in a sample solution and then taken out therefrom. The one end of the thin-tube type solid phase is disposed in a measurement cell and a sensing portion of a pH electrode disposed in the measurement cell is in the vicinity of the one end of the thin-tube type solid phase. The measurement cell and the thin-tube type solid phase are filled with a substrate solution so that a reaction takes place. Thereafter, the substrate solution in the thin-tube type solid phase is moved to the sensing portion by a solution feed pump. The output of the pH electrode at this timing is detected.

Abstract: The invention relates to a method of evaluating the immunological status of a subject comprising the steps of 1) determining the content of an antibody in a liquid sample from the subject using an immunoassay, wherein the reaction between the antibody of the sample and a ligand in the form of an antigen, an antibody or a hapten, the ligand being directed to the Fab region of the sample antibody, is carried out in the presence of other constituents of the sample to obtain a measurement 1, 2) determining the content of an antibody in the liquid sample using an immunoassay, wherein the reaction between the antibody of the sample and a ligand in the form of an antigen, an antibody or a hapten, the ligand being directed to the Fab region of the sample antibody, is carried out in the absence of other constituents of the sample to obtain a measurement 2, and 3) interrelating measurements 1 and 2 to express the interference and using the interference as a parameter for evaluating the immunological status of the subje

Abstract: A bacteriophage linked to an enzyme can replace an antibody in a system for detecting the presence of a bacteria in a sample. Specifically Brucella abortus (a pathogen which causes brucellosis in cattle) can be detected using Brucella bacteriophage for the virus, urease for the enzyme linked to the bacteriophage, m-maleimidobenzoyl-N-hydrosysuccimide ester as a coupling reagent, sera from mice immunized with Brucella bacteriophage for a detector antibody, urease conjugated to anti-mouse sheep antibody for an indicator, and urea with bromcresol purple as the substrate. The materials can be used in indirect (sandwich) or direct enzyme-linked viral assays (ELVirA).

Abstract: A set of contiguous and partially overlapping RNA sequences and polypeptides encoded thereby, designated as PS190 and transcribed from prostate tissue is described. These sequences are useful for the detecting, diagnosing, staging, monitoring, prognosticating, preventing or treating, or determining the predisposition of an individual to diseases and conditions of the prostate, such as prostate cancer. Also provided are antibodies which specifically bind to PS190-encoded polypeptide or protein, and agonists or inhibitors which prevent action of the tissue-specific PS190 polypeptide, which molecules are useful for the therapeutic treatment of prostate diseases, tumors or metastases.

Abstract: The invention relates to an immunochemical method for detecting deposit of Bacillus thuringiensis delta-endotoxin or pesticidally-active fragment thereof on a plant or tree. The invention further relates to kits for using such a method.

Abstract: Methods and apparatus for evanescent light fluoroimmunoassays are disclosed. The apparatus employs a planar waveguide and optionally has multi-well features and improved evanescent field intensity. The preferred biosensor and assay method have the capture molecules immobilized to the waveguide surface by site-specific coupling chemistry. Additionally, the coatings used to immobilize the capture molecules provide reduced non-specific protein adsorption.

Abstract: The invention concerns an immunological process for the detection of an analyte in a sample, in particular of tumor markers wherein for the reduction of interference substances containing a peptide sequence derived from the framework regions of the variable domain of the antibodies to be detected or the antibodies used for immune therapy or scintigraphy are added to the test preparation. Furthermore, the invention concerns the use of such substances for the reduction of interference of immunoassays, a suppressive agent and a process for the reduction of interference of immunoassays by the substances mentioned.

Abstract: The present invention describes a simple technique that provides a biologically relevant measure of the inhibitory effect of cyclosporine in vivo. This ability to measure response to cyclosporine may improve prediction of the efficacy of immunosuppressive treatment in patients and may allow optimal immunosuppression in individual patients.

Abstract: Receptors are disclosed that are antibodies that exhibit a binding affinity for an immune complex of a monoepitopic antigen and an antibody for such antigen that is substantially greater than the binding affinity for the monoepitopic antigen or the antibody for the monoepitopic antigen apart from the immune complex. Normally, the monoepitopic antigen has a molecular weight less than 1500 and is an organic compound. The antibodies of the present invention find use in a method for determining a monoepitopic antigen in a sample suspected of containing such antigen. The method comprises forming an immune sandwich complex comprising the monoepitopic antigen or an analog thereof, a first monoclonal antibody that binds to the monoepitopic antigen, and a second monoclonal antibody that is an antibody of the present invention and detecting the immune sandwich complex.

Abstract: The present invention relates to methods and compositions for the diagnosis, prevention, and treatment of tumor progression in cells involved in human tumors such as melanomas, breast, gastrointestinal, lung, and bone tumors, various types of skin cancers, and other neoplastic conditions such as leukemias and lymphomas. Genes are identified that are differentially expressed in benign (e.g., non-malignant) tumor cells relative to malignant tumor calls exhibiting a high metastatic potential. Genes are also identified via the ability of their gene products to interact with gene products involved in the progression to, and/or aggressiveness of, neoplastic tumor disease states. The genes and gene products identified can be used diagnostically or for therapeutic intervention.

Abstract: A cleavable signal element for use in quantitative and qualitative assay devices and methods is described. Binding of the chosen analyte simultaneously to a first and a second analyte-specific side member of the cleavable signal element tethers the signal-responsive moiety to the signal element's substrate-attaching end, despite subsequent cleavage at the cleavage site that lies intermediate the first and second side members. Assay devices comprising the cleavable signal elements are described, as are analytic methods adapted to their use. The analytic devices of the present invention may be adapted to detection using conventional CD-ROM and DVD readers.