Abstract:
Liquid and lyophilized reagents for determining prothrombin time and/or fibrinogen levels in a plasma sample are disclosed. The reagents preferably are based on recombinant rabbit tissue factor. Also disclosed is a purified preparation of recombinant rabbit tissue factor having unique properties, and a novel method for making PT reagents.
Abstract:
The present invention provides a method for determining thrombotic risk in an individual. The method involves determining the activity of Protein C and Protein S in the plasma of the individual thought to be at thrombotic risk by adding to a plasma sample obtained from the individual: (i) a first reagent in an amount sufficient to induce or activate coagulation in the plasma, (ii) a second reagent which activates endogenous protein C in the plasma, and (iii) a third reagent comprising calcium salts, phospholipids or tissue thromboplastin, or a combination thereof. To a second plasma sample from the same subject is added a reagent which induces or activates coagulation, and a buffer or other material which does not activate protein C, and a third reagent as described above. The time, rate or both, necessary for the conversion of endogenous fibrinogen to fibrin in both the first and second samples is measured. The same steps are performed on normal control plasma, and the difference or ratio in the times, rates, or both, obtained above are determined. The difference or ratio is indicative of the thrombotic risk in the subject. A kit adapted to carry out the method also is the subject of the present invention. The methods and kits of the invention in other embodiments may comprise a first reagent comprising a synthetic substrate, a second reagent which in the first sample from the subject activates protein C, and in the second sample, a second reagent which does not activate protein C. In these embodiments, the rates of hydrolysis of the synthetic substrates are measured and compared.
Abstract:
A fluid circulating and intercepting device (10) comprises a first (12) and a second block (11) facing each other with the interposition of an impermeable elastic and flexible diaphragm (13). The first block (12) is provided with at least one concavity (16) with its mouth close to the diaphragm (13) and into which opens out in a substantially axial direction a control fluid feed duct (17). The second block (11) is provided with ducts (14, 15) for circulation of the intercepted fluid which open out on the face in contact with the diaphragm (13), in correspondence with the concavity (16) in the first block (12).
Abstract:
An aqueous coenzyme reagent composition contains NADH, a carbonate/bicarbonate buffer (with a pH of about 9.5 - 11) and water. Both NADH and the buffer are at low concentrations, e.g., about 2 - 5 mM for NADH and about 2 - 15 mM for carbonate/bicarbonate. When this coenzyme reagent is mixed with an enzyme reagent, the mixture achieves a neutral pH. The combination of high pH, low NADH concentration and low buffer concentration permit the aqueous reagent to be stored for extended periods at low temperatures without NADH degrading to form impurities which interfere with or inhibit enzyme activity, such as the activity of lactate dehydrogenase or malate dehydrogenase in an assay for ALT or AST.
Abstract:
To determine the biological activity of protein S in a sample of human plasma, the suitably diluted sample is added to a substrate formed from plasma deficient in protein S, in which protein C is activated. The functionality of protein S is evaluated by a coagulometric test using bovine thromboplastin with added calcium as the phospholipid source.
Abstract:
A method for determining the concentrations of total calcium and at least one monovalent ion in a sample includes the steps of mixing the sample with a diluent that has a pH within the range pH 6.5 to 7.0 and includes 2-amino-2-hydroxymethyl-1,3 propanediol phosphate and is free of the monovalent ion. An aliquot of the diluted sample is concurrently contacted with a calcium-specific ion selective electrode and an ion selective electrode specifically responsive to the monovalent ion, the response of the calcium-specific ion selective electrode is measured as an indication of the concentration of total calcium in the sample, and the response of the monovalent ion specific ion selective electrode is measured as an indication of the concentration of the monovalent ion in the sample.
Abstract:
A liquid handling system includes flow network module structure that defines a contained array of flow channels and a plurality of valves for controlling liquid flow through the flow channel array. The flow network module structure is adapted to be connected to an external source for applying a pressure differential to the flow network array to produce liquid flow within passages of the array. Also incorporated in the flow network module is chamber structure that is connected to the flow channel array and that has port structure in an outer surface of the module structure. Valve structure on the module structure is movable between a first position in which the port structure is closed and a second position in which the port structure is opened, the valve structure including actuator structure for moving a valve member between the first and second positions. Liquid transfer structure, including transport structure and probe structure carried on the transport structure, is adapted to cause movement of the valve structure from its first position to its second position concurrently with the movement of the probe structure into alignment with the chamber port structure for delivery of a quantity of sample material to the sample chamber and subsequent flow through the flow network array for interaction with an auxiliary fluid and transfer to an associated utilization device under the influence of an external pressure source.
Abstract:
An analysis system includes analysis station structure, sample station structure spaced from the analysis station structure along a straight line path, support shaft structure disposed along an axis parallel to the straight line path, and a transport carriage with probe structure mounted on the carriage. The transport carriage is mounted on the support shaft structure for movement along that shaft and is keyed thereto for pivoting movement in response to rotation of the shaft. A first drive includes a drive motor and cable structure coupled between the carriage and the drive motor for moving the transport carriage along the shaft to selectively position the probe structure at the sample and analysis stations, and a second drive rotates the shaft for inserting the probe into and withdrawing the probe from chamber structure at the sample and analysis stations. Metering means coupled to the probe flows liquid into and discharges liquid from the probe.