and the peak time, which was the average of the time to peak concentration and the time to the second highest
concentration. Data were tested for statistical signifi- cance between genotypes by analysis of variance
ANOVA and the Kruskal – Wallis test, and between genotypes and time by ANOVA for repeated measures
including the BMI and age as co-variants in all analy- ses. A probability value less than 0.05 was considered
significant. The maximum peak of triacylglycerol was used in small-TRL and AUC of triacylglycerol in small-
TRL as dependent variables and did stepwise multiple regression to identify other concomitant variables. The
independent variables included age, BMI, apo A-IV genotype, basal cholesterol, HDL-C and triacylglycerol
values. Discrete variables were divided into two classes for analysis. All data presented in the text and tables
are expressed as mean 9 S.D. adjusted by BMI and age as co-variant.
3. Results
The baseline characteristics of the study subjects are shown in Table 1. No differences were observed in any
of the lipid parameters studied or in the percentage of smokers between the A-IV 360His + H + , n = 9
and A-IV 360GlnGln GG, n = 42 subjects. The group of subjects with the apo A-IV 360His mutation
had a slightly greater mean age and also a lower BMI compared with homozygotes for the apo A-IV 360Gln
allele. In order to adjust by the effect of these variables BMI and age have been included as covariant in all
statistical analyses and all data are presented as ad- justed values by these variables.
Plasma cholesterol and triacylglycerol responses fol- lowing the fat load test are shown in Fig. 1. There was
no significant difference in either of these two parame- ters between the two subject groups as was shown by
the ANOVA in which p1 indicates the effect of the genotype, p2 the effect of time and p3 the effect of the
interaction genotype-time. According to the effect of time, a significant change was observed in triacylglyc-
erol indicated by an increase in this parameter in the curves of both subject groups over the postprandial
period. Carriers of the apo A-IV 360His allele presented higher plasma triacylglycerol levels at the 11th hour in
comparison with those homozygotes for the apo A-IV 360Gln allele.
Triacylglycerol concentrations during the postpran- dial period for large and small-TRL fractions are
shown in Fig. 2. In apo A-IV 360GlnGln ho- mozygotes, triacylglycerol levels in large-TRL remained
significantly higher than baseline levels for the first 8 h and returned to baseline at the 11th hour. However,
carriers of the apo A-IV 360His mutation maintained triacylglycerol levels in the large-TRL above baseline
Fig. 1. Line plots of postprandial plasma cholesterol A and triacyl- glycerol B, response in apolipoprotein apo A-IV 360 GlnGln
subjects solid line, and apo A-IV 360His + subjects dotted line, His + indicates HisHis or HisGln. For each group, the levels
at each time point were averaged, adjusted by body mass index BMI and age as co-variant and expressed as mean 9 S.E.M. P1, genotype
effect; P2, time effect; P3, genotype by time interaction. MANOVA for repeated measures. Tukeys test for normally distributed vari-
ables or Kruskal – Wallis test for nonparametric variables.
over the entire study period Fig. 2A. Both groups presented elevated postprandial triacylglycerol levels in
the small-TRL in the first 6 h of the lipemia. However, after that period, apo A-IV 360GlnGln subjects pre-
sented values significantly lower than baseline Fig. 2B. Carriers of the apo A-IV 360His mutation presented
higher triacylglycerol levels in small TRL fractions compared with homozygotes for the apo A-IV 360Gln
allele, as shown by ANOVA for repeated measures significant genotype effect, P B 0.008. Moreover, sub-
jects with the apo A-IV 360His allele presented higher triacylglycerol levels in the small-TRL at baseline time
and at 1, 3, 5, 6 and 11 h than apo A-IV 360GlnGln subjects. Likewise, carriers of the apo A-IV 360His
allele presented higher triacylglycerol levels in the large- TRL at 11 h. These findings indicate that triacylglycerol
levels in carriers of the apo A-IV 360His allele remain elevated even after the 11th hour of postprandial
lipemia study when homozygotes for the apo A-IV
360Gln allele had already returned to their baseline levels. The AUC of the small-TRL triacylglycerol
Table 2 and the maximum peak of triacylglycerol in the small-TRL Table 3 were significantly greater in
apo A-IV 360His subjects 0.77 9 0.46 mmoll com- pared with homozygotes for the apo A-IV 360Gln allele
0.58 9 0.24 mmoll but these differences disappeared when one adjusted by the baseline values 0.25 9 0.18
vs. 0.25 9 0.16; P B 0.965.
The distribution of plasma cholesterol within the different TRL fractions was examined. In apo A-IV
360GlnGln subjects cholesterol in large-TRL was sig- nificantly higher than baseline values during the first 8
h and returned to baseline by the 11th hour. However, in apo A-IV 360His + subjects, it was only signifi-
cantly higher between hours 2 and 8 Fig. 3A. No significant differences were observed in the levels of
cholesterol transported in the large-TRL between both
Table 2 Area under curve AUC for the different lipid parameters examined
according to apolipoprotein apo A-IV 360GlnHis polymorphism adjusted by body mass index BMI and age as co-variant
a
P value 360GlnGln 42
360His+ 9 2601 9 423
Total cholesterol 2654 9 612
0.835 Triacylglycerol
0.242 1096 9 445
1307 9 587 0.960
LDL cholesterol 1509 9 440
1500 9 559 HDL cholesterol
773 9 249 0.832
790 9 184 0.862
Apo B 434.4 9 125.7
426.0 9 181.3 632.3 9 91.5
Apo A-I 649.1 9 136.9
0.684 428 9 212
Large TRL-TG 0.381
513 9 352 0.040
Small TRL-TG 282 9 125
384 9 237 2.30 9 2.39
2.83 9 2.0 0.236
Large TRL-RP 1.23 9 1.09
1.13 9 0.76 0.077
Small TRL-RP 0.780
36.8 9 24.1 Large TRL-B48
41.2 9 33.2 14.2 9 14.4
36.0 9 37.3 0.120
Small TRL-B48 70.9 9 72.8
Large TRL-B100 55.7 9 31.5
0.668 Small TRL-B100
0.410 2668 9 1913
1909 9 985 0.480
Large TRL-A-IV 13.9 9 5.1
12.9 9 2.5 2.0 9 1.6
1.7 9 1.9 0.560
Small TRL-A-IV
a
TG, triacylglycerol; RP, retinyl palmitate; TRL, triacylglycerol rich lipoprotein; 360His+ indicates apo A-IV 360HisGln or HisHis
genotypes. Cholesterol and triacylglycerol are in mmoll min, apo B, apo A-I, apo A-IV and RP are in gl min, B-48 and B-100 in arbitrary
unitsl min. One-way analysis of variance ANOVA.
Fig. 2. Line plots of postprandial triacylglycerol response in large triacylglycerol rich lipoproteins TRL A and small TRL B, re-
sponse in apolipoprotein apo A-IV 360 GlnGln subjects solid line, and apo A-IV 360His + subjects dotted line, His +
indicates HisHis or HisGln. For each group, the levels at each time point were averaged, adjusted by body mass index BMI and age as
co-variant and expressed as mean 9 S.E.M. P1, genotype effect; P2, time effect; P3, genotype by time interaction. MANOVA for repeated
measures. Tukeys test for normally distributed variables or Kruskal – Wallis test for nonparametric variables.
groups of subjects. Carriers of the apo A-IV 360His mutation presented a greater postprandial cholesterol
levels in the small-TRL than apo A-IV 360GlnGln subjects genotype effect, P B 0.011;6 ANOVA Fig.
3B. Moreover, when the differences between both groups were studied at each time point in the postpran-
dial lipemia study, subjects with the apo A-IV 360His mutation were found to present higher cholesterol levels
Table 3 Maximal postprandial triacylglycerol and RP increase and peak time
according to apo A-IV 360 His polymorphism adjusted by BMI and age as co-variant
a
360 P value
360His+ 9
GlnGln 42
Peak Total TG
3.33 9 1.25 0.100
2.62 9 0.96 mmoll
0.439 1.61 9 1.08
Normalized 1.37 9 0.77
peak Peak
Large 1.20 9 0.67
0.821 1.25 9 0.90
TRL-TG mmoll
0.88 9 0.53 0.96 9 0.68
0.729 Normalized
peak 0.77 9 0.46
0.58 9 0.24 0.046
Peak Small
TRL-TG mmoll
Normalized 0.25 9 0.16
0.965 0.25 9 0.18
peak
a
TG, triacylglycerol; TRL, triglyceride rich lipoprotein; 360His+ indicates apo A-IV 360HisGln or HisHis genotypes.
One-way analysis of variance ANOVA.
Fig. 3. Line plots of postprandial cholesterol response in large triacylglycerol rich lipoproteins TRL A and small TRL B, re-
sponse in apolipoprotein apo A-IV 360 GlnGln subjects solid line, and apo A-IV 360His + subjects dotted line, His +
indicates HisHis or HisGln. For each group, the levels at each time point were averaged, adjusted by body mass index BMI and age as
co-variant and expressed as mean 9 S.E.M. P1, genotype effect; P2, time effect; P3, genotype by time interaction. MANOVA for repeated
measures. Tukeys test for normally distributed variables or Kruskal – Wallis test for nonparametric variables.
and the apo A-IV 360His polymorphism was also a significant predictor of the variability in the maximum
peak of small-TRL-TG P = 0.05, accounting for 4.4 of the variance.
4. Discussion
