Quantitative Assessment of Serum Amino Acids and Association with Early-Onset Coronary Artery Disease

Figures & data

Table 1 Demographic and Clinical Characteristics of EOCAD Patients and Controls

Variables	EOCAD (n = 128)	Control (n = 64)	p-values
Gender, male n (%)^#	126 (98.44)	63 (98.44)	1.000
Age, years*	44.27 ± 5.26	44.82 ± 5.12	0.512
BMI (kg/m^2)*	26.68 ± 5.43	25.78 ± 4.92	0.266
Hypertension, n (%) ^#	32 (25.00)	14 (21.09)	0.765
Diabetes, n (%) ^#	26 (20.31)	17 (13.28)	0.426
Smoking, n (%) ^#	68 (53.13)	21 (32.81)	0.012
Drinking, n (%) ^#	70 (54.69)	31 (48.44)	0.506
FBG, mmol/l*	6.08 ± 3.22	5.02 ± 2.89	0.027
TG, mmol/l *	2.20 ± 1.92	1.62 ± 1.58	0.038
TC, mmol/l *	5.02 ± 1.59	4.90 ± 1.60	0.623
HDL-C, mmol/l *	1.09 ± 0.38	1.12 ± 0.42	0.619
LDL-C, mmol/l *	2.77 ± 1.23	2.46 ± 1.08	0.088
Lp(a), mmol/l *	299.27 ± 287.65	212.30 ± 210.78	0.033
SCr, μmol/l *	74.56 ± 20.22	76.38 ± 21.09	0.563
Myocardial Infarction, n (%)	64 (50.00)	-	-

Notes: ^#Categorical variables are expressed as percentages. The p-value of the categorical variables was calculated by χ² test. p-values < 0.05 are shown in bold font. *Continuous variables are expressed as mean ± SD. The p-value of the continuous variables was calculated by the unpaired t test. p-values < 0.05 are shown in bold font.

Abbreviations: EOCAD, early-onset coronary artery disease; BMI, body mass index; FBG, fasting blood glucose; TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; Lp(a), lipoprotein(a); TC, total cholesterol; SCr, serum creatinine.

Table 2 Targeted Amino Acid Information

Amino Acid	CAS Number	M.W. (Da)	Formula
Glycine	56-40-6	75.067	C2H5NO2
L-Alanine	56-41-7	89.093	C3H7NO2
β-Alanine	107-95-9	89.093	C3H7NO2
4-Aminobutyric acid	56-12-2	103.120	C4H9NO2
L-Serine	56-45-1	105.093	C3H7NO3
L-Proline	147-85-3	115.130	C5H9NO2
L-Valine	72-18-4	117.146	C5H11NO2
L-Threonine	72-19-5	119.119	C4H9NO3
4-Hydroxyproline	51-35-4	131.130	C5H9NO3
L-Asparagine	70-47-3	132.118	C4H8N2O3
L-Ornithine	3184-13-2	132.161	C5H12N2O2
L-Aspartic acid	56-84-8	133.103	C4H7NO4
L-Glutamine	56-85-9	146.145	C5H10N2O3
L-Lysine	56-87-1	146.188	C6H14N2O2
L-Glutamic acid	56-86-0	147.129	C5H9NO4
L-Methionine	63-68-3	149.211	C5H11NO2S
L-Histidine	71-00-1	155.155	C6H9N3O2
5-Hydroxylysine	1190-94-9	162.187	C6H14N2O3
L-Phenylalanine	63-91-2	165.189	C9H11NO2
1-Methyl-L-histidine	332-80-9	169.181	C7H11N3O2
3-Methyl-L-histidine	368-16-1	169.181	C7H11N3O2
L-Arginine	74-79-3	174.201	C6H14N4O2
L-Citrulline	372-75-8	175.186	C6H13N3O3
L-Tyrosine	60-18-4	181.189	C9H11NO3
L-Tryptophan	73-22-3	204.225	C11H12N2O2

Abbreviations: CAS, chemical abstracts service; M.W, molecular weight.

Figure 1 Serum levels of 4-Hydroxyproline in different sample pool groups. To compare with control (14.622 ± 1.237 μmol/L, n = 8, p < 0.001) and CAD (without MI) groups (13.785 ± 3.031 μmol/L, n = 8, p < 0.001), the serum levels of 4-Hydroxyproline is the lowest in MI group (8.503 ± 1.467 μmol/L, n = 8).

Table 3 Associations Between Serum 4-Hydroxyproline Levels and Presence of MI

Adjustment Models	OR 95% CI	p-values
Model 1: Crude, no adjustment	-	<0.001
Model 2: Adjusting for smoking, FBG, TG, and Lp (a).	0.871 (0.836–0.912)	<0.001
Model 3: Adjusting for age, BMI, hypertension, diabetes, smoking status, drinking status, FBG, TG, TC, SCr, HDL-C, LDL-C, and Lp(a).	0.863 (0.822–0.901)	<0.001

Abbreviations: MI, myocardial infarction; BMI, body mass index; FBG, fasting blood glucose; LDL-C, low-density lipoprotein cholesterol; TG, triglyceride; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; TC, total cholesterol; SCr, serum creatinine.

Figure 2 Serum 4-Hydroxyproline levels in patient and control groups. Compared with the controls (16.433±4.562 μmol/L, n = 64, p < 0.001) and the CAD (without) patients (15.223±4.225 μmol/L, n = 64, p = 0.122), the serum 4-Hydroxyproline levels were the lowest in the MI patients (9.889 ± 3.635 μmol/L, n = 64).

Figure 3 Negative correlation between serum 4-Hydroxyproline and cardiac troponin I (cTn I) levels in MI patients (r = −0.667, 95% CI: −0.7847 to −0.5046, p < 0.001).