Methods of diagnosing muscle damage

Abstract

A method for assessing muscle damage in a biological sample obtained from a subject is disclosed. The method involves obtaining a biological sample from a subject being assessed for muscle damage, and evaluating the sample for the presence or absence of a myofilament protein modification product. The method can also be used to assess the extent and/or type of muscle damage in a subject by studying the profile of myofilament protein modification products detected in the sample taken from the subject. The invention further provides a method for screening for an agent which modulates the level of a myofilament protein modification product present in a biological sample or for a calcium sensitizing agent. The invention is applicable to cardiac muscle and skeletal muscle.

1 . A method for assessing hypoxic cardiac muscle damage in a subject, said method comprising the steps of
 (a) contacting a processed or unprocessed biological sample from a body fluid of said subject with a compound that specifically recognizes and binds to a fragment of a cardiac troponin or a complex of said fragment and a myofilament protein or fragment thereof to form a detectable complex; and   (b) detecting said detectable complex,   
       wherein the presence, absence, or amount of said detectable complex is indicative of hypoxic cardiac muscle damage in said subject. 
     
     
         2 . The method of  claim 1 , wherein said cardiac troponin is troponin I (cTnI). 
     
     
         3 . The method of  claim 1 , wherein the subject is a human. 
     
     
         4 . The method of  claim 1 , wherein said body fluid is selected from the group consisting of whole blood, serum, plasma, lymphatic fluid, amniotic fluid, cerebrospinal fluid, and urine. 
     
     
         5 . The method of  claim 1 , wherein said compound is an antibody or antibody fragment. 
     
     
         6 . The method of  claim 1 , wherein said muscle damage is from myocardial infarction. 
     
     
         7 . The method of  claim 1 , wherein said muscle damage is indicative of the efficacy of treatment of the myocardium. 
     
     
         8 . The method of  claim 7 , wherein said treatment is preconditioning of the myocardium. 
     
     
         9 . The method of  claim 7 , wherein said treatment is cardioplegia. 
     
     
         10 . The method of  claim 1 , further comprising
 (c) measuring the amount of at least a second myofilament protein or fragment thereof, and   (d) calculating the ratio of said fragment of a cardiac troponin and said second myofilament protein.   
     
     
         11 . The method of  claim 10 , wherein said second myofilament protein is tropomyosin. 
     
     
         12 . The method of  claim 10 , wherein said second myofilament protein is myosin light chain 1. 
     
     
         13 . The method of  claim 10 , wherein said second myofilament protein is α-actinin. 
     
     
         14 . A kit for assessing hypoxic cardiac muscle damage in a subject, comprising
 (a) a compound that specifically binds to a fragment of a cardiac troponin or a complex of said fragment and a myofilament protein or fragment thereof; and   (b) a second compound that specifically binds to a second myofilament protein or fragment thereof; and   (c) instructions explaining how to use the kit to assess cardiac muscle damage using the biological sample from said subject.   
     
     
         15 . The kit of  claim 14 , wherein said cardiac troponin is troponin I. 
     
     
         16 . The kit of  claim 14 , wherein either or both of said compounds are antibodies or antibody fragments. 
     
     
         17 . The kit of  claim 14 , wherein said second myofilament protein is tropomyosin. 
     
     
         18 . The kit of  claim 14 , wherein said second myofilament protein is myosin light chain 1. 
     
     
         20 . The kit of  claim 14 , wherein said second myofilament protein is α-actinin.