efflux from cells in different tissues into HDL [17 – 19]. Data also exists suggesting that apo A-IV may be
involved in the regulation of food consumption [20]. Studies in rats have documented that apo A-IV infusion
and injection can reduce food intake [21 – 23]. While the physiological mechanism of this effect is not clear, it
has been suggested that apo A-IV may enter the central nervous system CNS to perform this function. Both
serum and cerebrospinal fluid apo A-IV levels increase markedly as a result of lipid consumption [22 – 24]. Apo
A-IV may inhibit gastric acid secretion in rats and reduce the severity of gastric ulceration by a mechanism
involving the CNS [25,26]. Moreover, in a transgenic study by Duverger et al. [27], it was reported that apo
A-IV had arteriosclerosis-protective potential in human apo A-IV gene transgenic mice. In another transgenic
mouse study by Qin et al. [28], an antioxidant function of apo A-IV was noted.
The effects of age, gender, and lifestyle factors smoking, alcohol consumption, and use of medication
for diabetes, cholesterol-lowering, thyroid disease, or hormone replacement therapy on human plasma apo
A-IV have not been well studied. Available data on relationships between plasma apo A-IV and various
physiological parameters age, gender, BMI, percent body fat, girth, blood glucose, and lipid levels are
reviewed in this manuscript. Elucidating such effects and relationships is helpful for understanding lipid
metabolism and its links to coronary heart disease CHD. Thus far, little is known about the relationship
between apo A-IV and other apolipoproteins, how life style influences apo A-IV levels, and what impact
healthmedication status has on plasma apo A-IV lev- els. In order to further elucidate apo A-IV physiology,
the influences of biological variables on human plasma apo A-IV levels were assessed in 723 participants in the
present study.
2. Subjects and methods
Seven hundred and twenty-three human subjects, who attended a residential lifestyle intervention pro-
gram The Pritikin Longevity Center, Santa Monica, CA as previously reported [29], participated in this
study. The participants consisted of 372 males and 351 females, respectively. More than 90 of them were
Caucasians. Their physiological parameters of age, BMI weight kgheight m
2
, percent body fat, girth, and lipid profile are summarized in Table 1. Of all
subjects, 10 were current smokers, and 74.6 con- sumed alcohol more than one drinkper week. With
regard to the health status of these subjects, 10 were on medication for diabetes, 16.5 were on cholesterol-
lowering medication, 14.8 were on thyroid medica- tion, and 35.9 of female subjects were on hormone
replacement therapy.
Fasting blood samples were drawn from all subjects at the time of entry into the program baseline and
were stored in 10 ml tubes containing either SST clot- activating gel Bectin-Dickinson vacutainer system for
lipid and glucose measurements, or 0.1 EDTA for apolipoprotein measurements. Samples for lipid and
glucose measurements were allowed to clot, and then were further centrifuged for 15 min at 2500 rpm to
isolate serum. The total cholesterol TC, high density lipoprotein cholesterol HDL-C, triglyceride TG, and
glucose levels were measured by standardized auto- mated enzymatic methods Smith-Kline Beecham Labo-
ratories. The low density lipoprotein cholesterol LDL-C was calculated by subtracting the HDL-C and
TG5 an estimation of TG-rich lipoprotein cholesterol from TC, as described by Friedewald et al. [30]. For
samples with TG levels over 400 mgdl, their TG-rich lipoprotein cholesterol levels were determined by ultra-
centrifugation using the method reported by Havel et al. [31].
Plasma samples for apolipoprotein measurement were obtained by centrifugation of whole blood at 2500
rpm for 30 min. Plasma apo A-IV levels were measured by immunoelectrophoresis using a commercially avail-
able kit HYDRAGEL apo A-IV, Sebia, France. Plasma apo E levels were measured by an enzyme
linked immunosorbent assay, also using a commercially available kit obtained from the Perimmune Corpora-
tion, Rockville, MD. Plasma apo A-I and apo B100 were determined by immunoturbidimetric assays with a
Spectrum CCX analyzer Abbott Diagnosis [32,33]. Within and between measurements, the coefficients of
variation for all assays were B 10. For identification of apo A-IV-12 polymorphism, genomic DNA was
Table 1 Biological characteristics of subjects mgdl, mean 9 S.D.
P values
a
Total Males
Females n = 723
n = 351 n = 372
57.4 9 12.9 58.7 9 12.3
56.1 9 13.4 Age years
B 0.01
29.5 9 6.4 30.4 9 5.8
BMI 28.5 9 6.8
B 0.01
29.8 9 7.8 27.9 9 7.9
BF
b
31.9 9 7.1 B
0.01 40.7 9 6.7
42.5 9 5.7 Girth
c
38.6 9 7.0 B
0.01 186 9 107
B 0.01
171 9 97 TG
154 9 80 211 9 42
208 9 44 TC
215 9 41 0.04
123 9 35 124 9 36
LDL-C 121 9 35
ns
d
55.6 9 15.6 48 9 12
HDL-C 62 9 15
B 0.01
Apo A-I 139 9 21
132 9 17 147 9 22
B 0.01
113 9 31 116 9 32
Apo B 109 9 30
B 0.01
Apo E 11.2 9 4.5
11.5 9 4.5 10.8 9 4.5
0.04 107 9 44
96 9 39 Glucose
B 0.01
101 9 42
a
Males vs females.
b
Percentage of body fat, estimated by skin-fold measurement [51,52].
c
In inches.
d
Not statistically significant.
Table 2 Effects of gender, smoking and alcohol on the apolipoprotein apo A-IV Levels
On-medication subjects Normal subjects
All subjects Levels mgdl
P value
a
n Levels mgdl
P value n
n Levels mgdl
P value 14.7 9 4.1
316 15.3 9 5.3
Total 407
723 15.0 9 4.6
Gender 14.9 9 4.1
123 16.6 9 6.1
249 Males
372 15.5 9 4.9
158 Females
14.5 9 4.0 ns
b
193 14.4 9 4.5
B 0.001
351 14.4 9 4.3
B 0.01
Smoking 14.8 9 4.0
21 Yes
15.6 9 4.8 52
73 14.9 9 4.0
No 349
14.6 9 3.6 ns
293 15.2 9 5.3
ns 650
15.0 9 4.7 ns
Alcohol intake 15.1 9 4.05
231 15.1 9 4.90
318 Yes
549 14.8 9 4.45
89 No
14.7 9 4.09 ns
85 15.7 9 6.15
ns 174
15.4 9 5.18 ns
a
t-Test P value.
b
Not statistically significant. Table 3
The effects of diseasemedication status on apolipoprotein apo A-IV levels
a
Diabetesb
b
CLMc
b
TMd
b
HRTe
b
P values Normala
18.2 9 7.7 16.7 9 6.0
Males 17.1 9 5.8
14.8 9 4.7 n = 51
ba
n = 77 n = 24
– B
0.001 n = 249
ab
17.0 9 4.3 14.3 9 3.2
14.8 9 4.3 14.5 9 4.0
13.9 9 4.5 Females
n = 20
ba ,bc
,be
n = 42
cb
n = 82 n = 127
ea ,eb
n = 158
ab
B 0.01
17.8 9 7.4 15.9 9 5.3
15.4 9 4.7 14.7 9 4.1
All subjects n = 71
ba ,bc
,bd
n = 119
bc
n = 106
bd
– n = 407
ab
B 0.001
a a,b,c,d,e
The different superscript letters represent that a statistically significant difference exists between the two means.
b
Subject groups, Diabetes = on diabetic medication, CLM = on cholesterol lowering medication, TM = on thyroid medication, and HRT = on hormone replacement therapy.
PB0.05; PB0.01; data analyzed by general linear models GLM procedure.
isolated from whole blood using the QIA amp Blood Kit Qiagen. The 360 bp polymorphism within the apo
A-IV gene was assessed as previously described by Tenkanen et al. [34].
SAS 6.12 and Systat 7.0 SPSS statistical programs were used to carry out hypothesis testing, correlation
and regression analysis. A statistical P value less than 0.05 was considered as a significant boundary.
3. Results
