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. Preferably, the myofilament protein modification product is a chemical adduct of a myofilament protein. 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 cardiac muscle damage in a subject, comprising:
 obtaining a biological sample from a subject being assessed for cardiac muscle damage; and   evaluating for the presence of one or more different myofilament protein modification products in the biological sample, at least one of said myofilament protein modification products being a chemical adduct of a myofilament protein selected from the group consisting of cardiac troponin I, cardiac troponin T and myosin light chain 1;   wherein the presence of at least one myofilament protein modification product which is a chemical adduct of a myofilament protein selected from the group consisting of cardiac troponin I, cardiac troponin T and myosin light chain 1 in the biological sample is indicative of cardiac muscle damage in said subject; and   wherein the chemical adduct of the myofilament protein is a post-translational modification of an intact myofilament protein, a post-translational modification of a degradation product of a myofilament protein, or a post-translational modification of a protein-protein complex of myofilament proteins.   
   
   
       2 . The method of  claim 1 , further comprising the step of assessing the amount of the one or more different myofilament protein modification products present in the biological sample as an indication of the extent of cardiac muscle damage in the subject. 
   
   
       3 . The method of  claim 1 , wherein the evaluating step comprises detecting the presence of at least two different myofilament protein modification products in the biological sample. 
   
   
       4 . The method of  claim 3 , further comprising the step of assessing the amounts of said at least two different myofilament protein modification products present in the biological sample and comparing the amounts as an indication of the extent of cardiac muscle damage in the subject. 
   
   
       5 . The method of  claim 3 , wherein said at least two different myofilament protein modification products are from the same protein. 
   
   
       6 . The method of  claim 3 , wherein said at least two different myofilament protein modification products are from different proteins. 
   
   
       7 . The method of  claim 6 , further comprising the step of assessing the ratio of said at least two different myofilament protein modification products as an indication of the extent of cardiac muscle damage in the subject. 
   
   
       8 . The method of  claim 1 , wherein the cardiac muscle damage is due to at least one condition selected from the group consisting of myocardial infarction, hypoxia, hypoxemia, ischemia, and reperfusion. 
   
   
       9 . The method of  claim 1 , wherein at least one of the myofilament protein modification products is a protein-protein complex comprising at least two polypeptides, at least one of said polypeptides being a chemical adduct of an intact protein or a fragment of a protein selected from the group consisting of cardiac troponin I, cardiac troponin T and myosin light chain 1. 
   
   
       10 . The method of  claim 1 , wherein at least one of the myofilament protein modification products is a chemical adduct of a degradation product of a myofilament protein selected from the group consisting of cardiac troponin I, cardiac troponin T and myosin light chain 1. 
   
   
       11 . The method of  claim 1 , wherein the chemical adduct of a myofilament protein is a myofilament protein modified by post-translational modification. 
   
   
       12 . The method of  claim 11 , wherein the post-translational modification is selected from the group consisting of phosphorylation, glycosylation, myristylation, phenylation, acetylation, nitrosylation, and sulfation. 
   
   
       13 . The method of  claim 9 , wherein the chemical adduct of a myofilament protein is a protein-protein complex modified by post-translational modification. 
   
   
       14 . The method of  claim 13 , wherein the post-translational modification is selected from the group consisting of phosphorylation, glycosylation, myristylation, phenylation, acetylation, nitrosylation, and sulfation. 
   
   
       15 . The method of  claim 10 , wherein the chemical adduct of a myofilament protein is a degradation product of a myofilament protein modified by post-translational modification. 
   
   
       16 . The method of  claim 15 , wherein the post-translational modification is selected from the group consisting of phosphorylation, glycosylation, myristylation, phenylation, acetylation, nitrosylation, and sulfation. 
   
   
       17 . The method of  claim 1 , wherein the biological sample is selected from the group consisting of blood, blood serum, blood plasma, cardiac muscle tissue, a component of cardiac muscle tissue, and urine. 
   
   
       18 . A method for assessing cardiac muscle damage in a subject, comprising:
 obtaining at least two biological samples from a subject being assessed for cardiac muscle damage; and   evaluating for the presence of one or more myofilament protein modification products in the biological samples;   wherein said biological samples are not obtained simultaneously;   wherein at least one of the myofilament protein modification products is a chemical adduct of a myofilament protein selected from the group consisting of cardiac troponin I, cardiac troponin T and myosin light chain 1;   wherein the presence of one or more chemical adducts of said myofilament protein in at least one of said biological samples is indicative of cardiac muscle damage in the subject; and   wherein the chemical adduct of the myofilament protein selected from the group consisting of cardiac troponin I, cardiac troponin T and myosin light chain 1 is a post-translational modification of an intact myofilament protein, a post-translational modification of a degradation product of a myofilament protein or a post-translational modification of a protein-protein complex of myofilament proteins.   
   
   
       19 . The method of  claim 18 , further comprising assessing a change with time in the presence or amount of one or more chemical adducts of said myofilament protein in the biological samples, as an indication of the extent of cardiac muscle damage in the subject. 
   
   
       20 . The method of  claim 18 , wherein the evaluating step comprises detecting the presence of at least two different chemical adducts of a myofilament protein in the biological samples. 
   
   
       21 . The method of  claim 20 , further comprising the step of assessing a change with time in the amounts of said at least two different chemical adducts of a myofilament protein present in the biological samples, as an indication of the extent of cardiac muscle damage in the subject. 
   
   
       22 . The method of  claim 20 , wherein said at least two different chemical adducts of a myofilament protein are from the same protein. 
   
   
       23 . The method of  claim 20 , wherein said at least two different chemical adducts of a myofilament protein are from different proteins.