Compositions and methods for monitoring oxalate

Abstract

The present invention features compositions and methods for the detection or measurement of oxalate in a sample. Such compositions include test devices that provide for the rapid and accurate detection of oxalate in a sample from a biological fluid. Advantageously, the compositions can be used to monitor the oxalate levels of a patient at a point of care (e.g., at the patient's home, clinic, physician's office, or other clinical setting).

1 . A test device for detecting oxalate in a liquid sample, the device comprising oxalate oxidase, and an indicator system that provides a detectable reaction product in response to hydrogen peroxide production. 
     
     
         2 . The test device of  claim 1 , wherein the indicator system comprises 3-methyl-2-benzothiazolinone hydrazone (MBTH) and 3-(dimethylamino) benzoic acid (DMAB). 
     
     
         3 .- 8 . (canceled) 
     
     
         9 . A test device for detecting oxalate in a liquid sample, the device comprising a liquid permeable material defining the following portions in capillary communication:
 a) a site for application of a liquid sample, comprising a liquid permeable medium;   b) a second portion comprising a liquid permeable medium; and   c) a third portion that is the site for detecting the presence of oxalate at the test site, the third portion comprising a liquid permeable medium having an enzyme system having oxalate specific enzyme activity fixed to the medium at the test site, the enzyme system comprising oxalate specific enzyme, a substance which reacts with a reaction product of the oxalate specific enzyme, and an indicator material which reacts in the presence of the reaction product and changes color.   
     
     
         10 . The test device of  claim 9 , wherein the enzyme system has oxalate oxidase activity, the enzyme system comprising oxalate oxidase, a substance having peroxidative activity, an indicator material which is oxidized in the presence of peroxide and changes color. 
     
     
         11 .- 18 . (canceled) 
     
     
         19 . The test device of  claim 9 , wherein the liquid sample is blood, urine, or saliva. 
     
     
         20 . The test device of  claim 9 , further comprising a solid support selected from the group consisting of a sheet, tube, and stick. 
     
     
         21 . The test device of  claim 9 , which is used at a point of care. 
     
     
         22 . A method for detecting an analyte in a liquid sample, the method comprising:
 a) applying a liquid sample to the device of claim; and   b) detecting presence or absence of oxalate at a test site, wherein the presence of a detectable reaction product or color change at the test site identifies the presence of oxalate in the sample and the absence of color change at the test site identifies the absence of the oxalate in the sample.   
     
     
         23 . The method of  claim 22 , wherein the step (b) detects the level of oxalate in the sample. 
     
     
         24 . The method of  claim 22  for detecting oxalate in a liquid sample, the method comprising:
 a) applying a liquid sample to the device of  claim 1 ; 
 b) providing for the flow of the liquid from the site of application to the test site; and 
 c) detecting presence or absence of oxalate at a test site, wherein the presence of color change at the test site identifies the presence of oxalate in the sample and the absence of color change at the test site identifies the absence of the oxalate in the sample. 
 
     
     
         25 . The method of  claim 24 , the color change is detected by visual inspection. 
     
     
         26 . The method of  claim 25 , further comprising comparing the color change to a standard for detecting a difference in color of said sample. 
     
     
         27 . (canceled) 
     
     
         28 . A kit comprising a reaction mix, the reaction mix comprising an enzyme system having oxalate specific enzyme activity, the enzyme system comprising oxalate specific enzyme, a substance which reacts with a reaction product of the oxalate specific enzyme, and an indicator which reacts in the presence of the reaction product and changes color; and a color chart. 
     
     
         29 . The kit of  claim 28 , wherein the enzyme system has oxalate oxidase activity, the enzyme system comprising oxalate oxidase, a substance having peroxidative activity, an indicator which is oxidized in the presence of peroxide, and said substance having peroxidative activity and changes color. 
     
     
         30 . The kit of  claim 28 , wherein the enzyme system has oxalate decarboxylase activity, the enzyme system comprising an oxalate decarboxylase, a substance having formate dehydrogenase activity, and an indicator which is reduced in the presence of formate and changes color. 
     
     
         31 . The kit of  claim 28 , comprising one or more of a powdered reaction mix, a reconstitution buffer, and dispensing pipette. 
     
     
         32 . The kit of  claim 28 , further comprising a standard for detecting a difference in color of said sample 
     
     
         33 . The kit of  claim 28 , further comprising instructions for the use of the kit for the detection of oxalate. 
     
     
         34 . The kit of  claim 28 , which is used at a point of care. 
     
     
         35 .- 36 . (canceled)