. 2009 Mar 6;11(2):R34. doi: 10.1186/ar2639

Table 2.

Change in total (L+D) amino acid composition with age in normal cartilage, osteoarthritic articular, and meniscal cartilages

		Amino acid
		Asx	Ser	Leu	Ile	Glx	Ala
Normal articular cartilage	Mean (nmol/mg)	157.3	104.8	87.4	37.2	252.5	262
	r²	0.054	0.037	0.042	0.065	0.060	0.090
	Slope	-0.456	-0.233	-0.203	-0.120	-0.796	-1.040
	P value	0.327	0.418	0.399	0.293	0.297	0.198

OA articular cartilage	Mean (nmol/mg)	99.5	67.7	56.0	23.2	159.1	165.7
	r²	0.076	0.070	0.028	0.081	0.056	0.059
	Slope	0.419	0.278	0.237	0.196	0.532	0.645
	P value	0.141	0.157	0.377	0.129	0.208	0.196

OA meniscal cartilage	Mean (nmol/mg)	100.4	74.6	53.4	23.7	140.5	180.4
	r²	0.208	0.194	0.143	0.144	0.194	0.232
	Slope	-1.11	-0.78	-1.06	-0.458	-1.59	-2.57
	P value	0.011^a	0.015^a	0.040^a	0.039^a	0.015^a	0.007^a

Composition is presented in nanomoles per milligram of tissue wet weight. ^aDenotes significant value. Ala, alanine; Asx, asparagine + aspartate; Glx, glutamate + glutamine; Ile, isoleucine; Leu, leucine; OA, osteoarthritic; Ser, serine.