Palladium catalyzed heck arylation of 2,3-Dihydrofuran-effect of the palladium precursor

Article abstract of DOI:10.3390/molecules19068402

Heck arylation of 2,3-dihydrofuran with iodobenzene was carried out in systems consisting of different palladium precursors (Pd₂(dba) ₃, Pd(acac)₂, PdCl₂(cod), [PdCl(allyl)] ₂, PdCl₂(PhCN)<

Full text of DOI:10.3390/molecules19068402

Clinical Chemistry 43:7
209–1214 (1997)
Test Utilization and
Outcomes
1
Plasma malondialdehyde as biomarker for
oxidative stress: reference interval and effects of
life-style factors
Flemming Nielsen,* Bo Borg Mikkelsen, Jesper Bo Nielsen, Helle Raun Andersen, and
Philippe Grandjean
Malondialdehyde (MDA) is one of the most frequently
used indicators of lipid peroxidation. To generate reli-
able reference intervals for plasma malondialdehyde
Clinical research in the area of lipid peroxidation has been
hampered by the lack of a valid biomarker. One of the
most frequently used biomarkers providing an indication
of the overall lipid peroxidation level is the plasma
concentration of malondialdehyde (P-MDA), one of sev-
(
P-MDA), a reference sample group was established in
Funen, Denmark. The group consisted of 213 individu-
als (107 men, 106 women), ages 20–79 years. P-MDA was
measured in EDTA-treated plasma after derivatization
by thiobarbituric acid (TBA) and separation on HPLC.
UV detection was performed at 532 nm. A reference
interval was calculated as recommended by IFCC with
REFVAL 3.42. The estimated reference limits (0.025 and
1
eral byproducts of lipid peroxidation processes. Proper
utilization requires reliable reference intervals from large
unselected human populations and thorough evaluation
of the influence of age and gender, as well as other
variations within the population.
One of the prominent risk factors for increased lipid
peroxidation is smoking. Because of the presence of free
radicals in cigarette smoke [1, 2], increases in P-MDA may
occur [3–5]. Nevertheless, others failed to identify any
correlation between smoking status and P-MDA [6–8]. In
interpreting this evidence as well as other published
P-MDA results, the size of the studies, the selection of
subjects, and the quality of the P-MDA assay must be
taken into account.
0
.975 fractals) for the group were 0.36 and 1.24 ␮mol/L.
The data were analyzed for gender- and age-related
differences. Analysis of variance showed no interaction
between gender and age, but separate analyses showed
an independent effect of gender (P ؍ 0.03), but not of
age (P ؍ 0.11). Daily smokers had a slightly higher
average concentration of P-MDA than nonsmokers (P ؍
0
.05), and P-MDA correlated with daily exposure to
cigarette smoke (r ؍ 0.162; P ؍ 0.03). A positive correla-
tion was also demonstrated between P-MDA and
weekly alcohol consumption (r ؍ 0.153; P ؍ 0.03).
Within-subject and day-to-day variations of P-MDA
indicated that the potential of P-MDA as a biomarker
for individuals is questionable. However, on a group
basis, the present data support that P-MDA may be a
potential biomarker for oxidative stress.
We have quantified P-MDA by the thiobarbituric acid
(TBA) test. TBA-reactive substances (TBARS) formed in
plasma, urine, or tissue samples after a calibrated sample
pretreatment procedure primarily consist of MDA, which
forms a red adduct with two molecules of TBA (MDA-
TBA ) [9]. The adducts are separated by an HPLC method
2
originally described by Wong et al. [10] and Carbonneau
et al. [11], but modified for improvement of the selectivity
from nonidentified substances in plasma. Reference val-
ues for P-MDA for several individuals, with a selection
between different age groups as well as gender, have been
reported only in a selected group of blood donors [12].
The aim of this study was to establish and validate an
HPLC-based method for analysis of P-MDA, to determine
INDEXING TERMS: lipid peroxidation • reference intervals •
HPLC
Institute of Community Health, Odense University, Odense, Denmark.
*Address correspondence to this author at: Department of Environmental
Medicine, Odense University, Winsløwparken 17, DK-5000 Odense C, Den-
mark. Fax ϩ45 65 91 14 58; e-mail F.Nielsen@Winsloew.ou.dk.
1
Received November 25, 1996; revised March 7, 1997; accepted March 10,
Nonstandard abbreviations: P-MDA, plasma malondialdehyde; TBA,
1
997.
thiobarbituric acid; and TEP, 1,1,3,3-tetraethoxypropane.
1
209

1
210
Nielsen et al.: Plasma malondialdehyde as biomarker
a reference interval in a population-based sample group,
and to assess the possible influence of smoking on P-
MDA.
offered as an alternative. We reviewed the completed
questionnaire. All sampling of blood was performed
between 1400 and 1800 h during the months of September
and October, 1994. All blood samples were obtained by
the same phlebotomist. The participants were placed in a
supine posture and blood was drawn from a cubital vein
into 10-mL Venoject tubes with 0.1 mL of 0.47 mol/L
EDTA as anticoagulant (Terumo Europe, Leuven, Bel-
gium). Blood samples were kept at 5 °C until centrifuga-
tion at 1000g (3 h at maximum). Plasma was distributed
into sterile Cryo Vials (Greiner labortechnik, Fricken-
hausen, Germany) in volumes of 500 ␮L and was imme-
diately frozen to Ϫ80 °C until analysis.
Materials and Methods
establishment of reference sample group
The reference sample group was established on the basis
of a randomly selected group of 480 persons on Funen,
Denmark. The selection was performed by the Danish
Central Personal Registry (CPR) from criteria of equal
number of men and women, ages 20–79 years, and an
equal participation from individuals living in urban
(
Odense; 94% urbanization) and rural (Otterup and
Søndersø; 46% urbanization) municipalities. Two-hun-
dred forty of the randomly selected persons received a
standard questionnaire and were invited to participate in
the investigation. The questionnaire contained detailed
questions regarding former and present work, life-style
factors, exposure to toxic chemicals, exposure to air pol-
lution, use of prescribed drugs, and dietary and cooking
habits. Persons who did not respond to the first invitation
after 3 weeks received a written reminder. If the second
letter remained unanswered within another 2 weeks or
the person did not want to participate, a new person from
the same subgroup, gender, and age decade was given the
invitation to participate. No exclusion criteria were used.
At the request of the Regional Ethical Review Committee,
no unsolicited telephone contact was made. The overall
rate of participation in the groups from 20–79 years was
ϳ40%.
Analysis of the questionnaires indicated that the par-
ticipants did not deviate in any significant way from the
general Danish population. Approximately 60% of our
reference population was employed (the remaining par-
ticipants were attending school or university, retired, or
unemployed). Forty-three percent were smokers, 23% had
stopped smoking, and 32% had never smoked.
chemicals and reagents for analytical hplc
2-TBA, potassium dihydrogen phosphate, potassium hy-
droxide, sodium hydroxide, and orthophosphoric acid
85% were of analytical grade and purchased from Merck
(Darmstadt, Germany). 1,1,3,3-Tetraethoxypropane (TEP)
was purchased from Sigma (St. Louis, MO). Methanol was
of HiPerSolv grade and obtained by BDH Laboratory
Supplies (Poole, UK). All water used was demineralized
twice and filtered through a Milli-RO 10 Plus and a
Milli-Q Plus plant (final pore size 0.2 ␮m; Millipore,
Bedford, MA). A 10 mmol/L potassium dihydrogen phos-
phate solution was prepared and adjusted to pH 6.8 with
2.0 mol/L potassium hydroxide. The solution was filtered
by vacuum through a 0.45-␮m nylon 66 membrane (Su-
pelco 5–8060; Bellefonte, PA). A 42 mmol/L 2-TBA solu-
tion was prepared by dissolving 0.6 g of 2-TBA in 80 mL
of water, and then stirring and heating to 35–40 °C. The
solution was cooled to room temperature and filled with
water to 100 mL. The solution was stable for 2 days at
5 °C. The mobile phase consisted of 60:40 (by vol) 10
mmol/L potassium dihydrogen phosphate, pH 6.8:meth-
anol. The mobile phase was degassed by vacuum and
sonification before use.
statistics
hplc instrumentation and conditions
All statistical analyses of relations between P-MDA and
age, gender, and life-style factors were performed by the
statistical package SPSS for Windows, Version 6.1.3 (SPSS,
A Kontron HPLC system (Kontron Instruments, Z u¨ rich,
Switzerland) consisting of a Kontron HPLC pump 420, a
Kontron HPLC 360 autosampler with a 50-␮L injection
loop, and a Kontron UV detector 430 equipped with a
3-␮L flow cell was used. The system was controlled
through a Kontron Multiport Module and a personal
Chicago, IL). Analysis was performed on log -normalized
e
data. Correlations were calculated as Pearson’s correla-
tion coefficients. For comparison of means we used an
independent t-test. Reference intervals were calculated as
recommended by IFCC [13], with REFVAL 3.43 [14]. The
data were standardized to zero mean and unit variance
before exponential and modulus transformation to adjust
for skewness and kurtosis. The final distribution was not
significantly different from gaussian (Anderson–Darling’s
®
computer (Victor 433D). The column was a LiChroCART
®
250–4 packed with 5-␮m LiChrospher 100 RP-18
(Merck). The column was equipped with a guard column:
LiChroCART 4–4 packed with 5-␮m LiChrospher 100
RP-18. The elution was carried out at a flow rate of 0.5
mL/min. The column effluent was quantified at a wave-
length of 532 nm.
2
A ϭ 0.255, P Ϸ 1.0).
preanalytical factors
sample pretreatment
Each participant was invited to come to either the Depart-
ment of Environmental Medicine at Odense University, or
the local health center in Søndersø. A home visit was also
We added 100 ␮L of plasma to a 10-mL Pyrex centrifuga-
tion tube containing 700 ␮L of 1% orthophosphoric acid,
and vortex-mixed for 10 s. We then added 200 ␮L of 42

Clinical Chemistry 43, No. 7, 1997
1211
mmol/L 2-TBA solution, screwed the Teflon-lined cap on
tightly, and vortex-mixed the sample for 10 s, and then
heated it for 60 min in a water bath at 100 °C. Hereafter,
the sample was kept on ice until 10 min before HPLC
analysis. At that time the sample was vortex-mixed for
the MDA-TBA2 complex 2, and 10.77 for peak 3. No
correlation was found between any of the unidentified
peaks and the MDA-TBA peak. The peak in the blank
2
water sample was present in all blank samples, and the
mean area of this peak was subtracted from the area of the
plasma samples.
1
0 s, and 200 ␮L was transferred into a 2.0-mL Micrew-
tube (Simport Plastics, Qu e´ bec, Canada) containing 200
L of 1:12 (by vol) 2 mol/L sodium hydroxide:methanol.
The sample was vortex-mixed for 10 s and centrifuged for
min at 13 000g. We transferred 200 ␮L of the supernatant
The linearity of the detector response to different
concentrations of the compound was determined at
plasma concentrations of 0.59, 1.09, 1.59, 2.09, and 2.59
␮mol/L for the MDA-TBA2 complex. The calibration
curve for the compound added to water and plasma was
linear over the range investigated when peak areas were
plotted against concentrations and applied to a least-
squares regression equation (see Fig. 2). The regression
coefficient r was 0.999 for the plasma samples and 0.998
for the water samples.
Before analysis of each series, calibration curves from
supplemented water samples were prepared for three
calibration concentrations covering the expected concen-
tration range. The linear calibration curve was fitted
through the data points by linear regression.
The within-day repeatability of the method was eval-
uated by repeated analysis (n ϭ 10) of samples of supple-
mented plasma. Four concentrations of MDA were inves-
tigated: 0.5, 1.0, 1.5, and 2.0 ␮mol/L. The mean
background of MDA-TBA2 response in blank samples
was subtracted from all the supplemented samples. The
average CVs were 1.6% (range 1.3–2.1%). The between-
day reproducibility and accuracy of the method was
assessed five consecutive days at three different concen-
trations in plasma (0.49, 0.75, and 1.32 ␮mol/L). Accuracy
is calculated as deviation in percent of the mean estimate
from the 5 days of analysis with the supplemented value.
The mean estimates, SDs, and CVs and deviations from
supplemented values are given in Table 1.
␮
3
to a 300-␮L glass vial, and injected a 50-␮L aliquot onto
the column. A calibration solution was prepared from
TEP solubilized in water. TEP undergoes hydrolysis to
liberate stoichiometric amounts of MDA. Calibration
curves from supplemented water samples were produced
for each day of analysis. Calibration samples can be
neutralized until 10 h before analysis. The 42 mmol/L
2
-TBA was stable for 4 months, but was freshly prepared
every second day. To avoid interfering peaks, after each
use the tubes were immediately placed in a detergent
solution and machine-washed and rinsed in Milli-Q-
treated water. The tubes were then soaked in 1% HNO3,
rinsed with Milli-Q water, flushed with 960 mL/L etha-
nol, then oven-dried. To maintain optimal separation
performance and avoid buffer precipitation, the column
was regenerated with 15 mL of Milli-Q water followed by
1
5 mL of methanol at a flow rate of 0.5 mL/min after each
day of analysis. The guard column was replaced after
ϳ300 injections.
Results
hplc method validation
Representative chromatograms for plasma from a healthy
volunteer (A), a supplemented water-based calibrator (B),
and a blank water sample (C) are shown in Fig. 1. Baseline
separation of MDA-TBA and two unidentified peaks (1
and 3) was achieved with the applied conditions (see Fig.
The relative recovery for the MDA-TBA complex was
2
2
assessed (n ϭ 10) at four concentrations: 0.5, 1.0, 1.5, and
2.0 ␮mol/L. The peak area from a supplemented plasma
sample was compared, after subtraction of the baseline
1
A). About 15 min was required for each analysis. The
retention times in minutes were 8.52 for peak 1, 9.67 for
Fig. 1. Chromatograms of (A) plasma from a
healthy volunteer containing 0.67 ␮mol/L
P-MDA (peak 2), (B) supplemented water
sample containing 1 ␮mol/L P-MDA, and (C)
blank plasma.

1
212
Nielsen et al.: Plasma malondialdehyde as biomarker
Table 2. Within-subject variation of P-MDA concentrations
in six individuals from six consecutive days.
Individual
Mean, ␮mol/L
CV, %
23.6
5.9
15.3
30.0
20.8
14.0
1
2
3
4
5
6
0.39
0.59
0.43
0.31
0.44
0.58
lated for each of these fractals. Additional reference
intervals were calculated for each age decade and for
women and men separately (Table 4).
Analysis of variance was used to reveal relations
between normalized P-MDA concentration in the three
Fig. 2. Calibration curve of the MDA-TBA2 complex, supplemented as
TEP in water and plasma.
2
0-year age groups and gender. The analysis revealed a
response, with the peak area from a supplemented water
sample. The plasma sample was prepared with equal
amounts of the TEP calibrator. The average recovery was
significant effect from gender (P ϭ 0.033), but apparently
not from age (P ϭ 0.109). No major interaction occurred
between gender and age (P ϭ 0.103). Men had slightly but
significantly higher P-MDA concentrations than women.
In the reference sample group, 92 were smokers and 122
were nonsmokers. Smokers had a significantly higher
9
9% (range 96.7–103.4%). The limit of determination for
P-MDA on the basis of a signal-to-noise ratio of 10:1 was
.05 ␮mol/L. The limit of detection, from a signal-to-noise
0
ratio of 3:1, was 0.02 ␮mol/L.
Stability of EDTA-treated plasma was investigated in a
plasma pool used for control samples. The samples were
stable at Ϫ80 °C for 6 months. We also compared the
response from serum and from plasma collected in
Venoject tubes with 0.13 mol/L sodium citrate, sodium
heparin, and 0.47 mol/L tripotassium EDTA. The mean
response of the MDA-TBA2 complex from 13 fasting
volunteers (7 men and 6 women, ages 20–33 years) was
Table 3. P-MDA values and CV for a group of six individuals
on six consecutive days.
Day
Mean, ␮mol/L
1
0.50
2
0.43
3
0.42
4
0.46
1
.16, 0.89, 1.27, and 0.26 ␮mol/L, respectively. Reproduc-
5
0.48
ibility calculated as CV was Ͻ10% only with EDTA as
anticoagulant (data not shown).
6
0.46
Group mean
Intraindividual variations were investigated in six
healthy volunteers (3 women and 3 men, ages 21–53
years). Blood samples were obtained in EDTA-treated
Venoject tubes from nonfasting individuals between 0800
and 0830 h for 6 consecutive days. To eliminate analytical
variations, analysis was performed for all individuals in a
single run. Within-subject variations are shown in Table 2
and the day-to-day variability for the group is shown in
Table 3.
0
.46
Group CV, %
.5
6
Table 4. Reference intervals for malondialdehyde
parametric estimate).
(
0
.025 and 0.975 fractiles,
0.90 confidence intervals,
Age intervals
␮mol/L
␮mol/L
The reference intervals are defined by the 0.025 and
20–39 years
n ϭ 80)
0–59 years
n ϭ 83)
0.33
1.15
0.39
1.18
0.39
1.40
0.36
1.24
0.41
1.29
0.30–0.36
1.04–1.28
0.37–0.41
1.02–1.46
0.36–0.42
1.19–1.76
0.34–0.37
1.14–1.37
0.39–0.43
1.14–1.53
(
0
.975 fractals, and the 0.90 confidence interval is calcu-
4
(
Table 1. Reproducibility and accuracy of MDA-TBA in
2
69–79 years
(n ϭ 50)
20–79 years
(n ϭ 213)
Men
20–79 years
(n ϭ 107)
Women
plasma.
Conc., ␮mol/L
MDA-TBA2
Mean
SD
CV, %
0.49
0.75
1.32
0.48
0.02
5.1
0.79
0.05
6.9
1.35
0.08
6.0
Deviation, %
2.0
5.3
2.3
0.33
1.22
0.31–0.36
1.08–1.41
2
1–79 years
(n ϭ 106)
Samples were from the same pool, analyzed once a day for 5 days. Deviation
is from the supplemented value.

Clinical Chemistry 43, No. 7, 1997
1213
P-MDA concentration (mean 0.66 ␮mol/L) than non-
smokers (mean 0.60 ␮mol/L) (P ϭ 0.05). Correlation
analysis revealed an association between P-MDA and the
number of hours of daily exposure to cigarette smoke (r ϭ
antioxidant to blood samples collected with heparin as
anticoagulant. Our findings of lowest P-MDA concentra-
tions in EDTA compared with heparin-treated plasma are
in agreement with the findings of Knight et al. [12].
Carbonneau et al. [11] found only minor differences in the
concentrations of MDA in serum or plasma with EDTA/
heparin as anticoagulants. The consistently lower MDA-
0
.162, P ϭ 0.03), but we found no clear correlation
between P-MDA and the number of cigarettes smoked
r ϭ Ϫ0.065, P ϭ 0.55). P-MDA was significantly corre-
lated with weekly alcohol consumption (r ϭ 0.153, P ϭ
.03). Weekly alcohol consumption was defined as units
(
TBA concentrations observed in EDTA-treated plasma
2
0
are probably related to EDTA chelation of iron in the TBA
assay as well as its weak activity as an antioxidant [10].
The difference in findings of effects of EDTA could reflect
the importance of having EDTA in the blood sampling
tube to ensure immediate reduction in iron-initiated li-
poperoxidation generated from the platelets. The higher
content of MDA in serum vs plasma could be explained
by lipoperoxides being formed during coagulation [10].
Thus, MDA measured in EDTA-treated plasma seems to
generate the least interfered indication of the degree of
lipid peroxidation at the time of blood sampling.
The within-subject variations (CV range 5.9–30%) re-
vealed that P-MDA probably cannot be used as a biomar-
ker or a diagnostic test on an individual basis. However,
on a group basis, the small day-to-day variability seems
more promising. We therefore suggest that P-MDA be
used only as a biomarker for the degree of lipid peroxi-
dation on a group basis.
The reference sample group in the study of Knight et
al. [12] consists of blood donors with a carefully screened
medical history. Our study deviates from this by its
selection criteria, random selection from the general pop-
ulation, instead of healthy subjects generally used as
controls in clinical studies. Other studies reporting total
P-MDA collected in EDTA sample tubes and measured as
a TBA adduct by HPLC do, however, report a similar
group mean of 0.6 ␮mol/L [10, 17]. Jiun and Hsien [19]
reported a mean of 0.9 ␮mol/L in a control group
consisting of 26 men and 40 women, ages 19–69 years.
Carbonneau et al. [11] reported a group mean for healthy
controls of 0.43 ␮mol/L in a group of 30 individuals, ages
23–70 years.
We found a significant correlation between P-MDA
and the number of hours of exposure to cigarette smoke,
but we found no correlation between P-MDA and the
number of cigarettes smoked by the individual (inhalation
was not taken into account). These findings, although
supporting that P-MDA is a weak biomarker for individ-
ual exposure, may also indicate that the recorded number
of cigarettes smoked by an individual may be a poor
estimate for the actual exposure to the smoke toxins.
Smokers are often exposed for longer periods to cigarette
smoke from other smokers than are nonsmokers. Also,
some smokers do not inhale the smoke from their own
cigarettes. These factors may affect the relation between
P-MDA and the exposure indicators. On a group basis,
however, our findings of a significantly increased P-MDA
in smokers is supported by the findings of Kalra et al. [4].
Cigarette smoke is known to increase production of
consumed during 1 week before completing the question-
naire.
Discussion
The formation of the MDA-TBA2 adduct is probably
initiated by a nucleophilic attack involving carbon-5 of
TBA onto carbon-1 of MDA, followed by dehydration and
a similar reaction of the intermediate MDA-TBA adduct
with a second molecule of TBA [15]. Hydroperoxides as
well as certain carbohydrates and amino acids could yield
products that would also produce a genuine MDA-TBA2
adduct upon heating with TBA [16], although the signif-
icance of these reactions is unclear. The anticoagulant
used during blood sampling (see below), the type and
strength of the acid used in the pretreatment procedure,
and the duration of heating affect the amount of adduct
produced. These facts, combined with differences in se-
lectivity with the numerous analytical methods, makes
the interpretation of previously reported P-MDA results
difficult. Nonetheless, the TBA assay may offer an indi-
cation of the current status of fatty acid peroxide forma-
tion and decomposition, and it is still commonly used as
a screening parameter. We therefore established a selec-
tive HPLC method that was optimized to produce accept-
able levels of precision and accuracy, but not too arduous
to use for population studies. We have modified the
analytical methods originally described by Wong et al.
[
10] and Carbonneau et al. [11]. We found the best
symmetrical peak shape and separation performance by
using only 10 mmol/L potassium dihydrogen phosphate
buffer (pH 6.8) and by reducing the flow rate to 0.5
mL/min. Although retention time was prolonged, the
baseline separation from a nonidentified back peak was
improved (peak 3, Fig. 1), eluting 1 min after the MDA-
TBA complex. No correlation was found between the
2
areas of background peaks 1 and 3 and the area of the
MDA-TBA2 adduct. The sensitivity of the method is
similar to the one reported by Young and Trimble and by
Richard et al. [17, 18]. Further advantages of this method
are that no extraction into organic solvents and tedious
evaporation procedures are required, and the use of an
isocratic eluant allows a higher number of samples to be
analyzed per day.
The previously reported findings of effects on P-MDA
from use of anticoagulant by blood sampling has been
somewhat contradictory. Richard et al. [18] found no
differences in amount of MDA-TBA adduct formed dur-
2
ing the sample preparation by addition of EDTA as

1
214
Nielsen et al.: Plasma malondialdehyde as biomarker
oxygen free radicals by polymorphonuclear leukocytes
20], and to decrease activities of some free radical scav-
tein properties in human blood plasma. Biochem J 1991;277:
33–8.
. Pr e´ J, Floch AL. Lipid-peroxidation products and antioxidants in
1
[
8
9
engers [21, 22]. Alcohol’s ability to induce lipid peroxida-
tion has been related to hypotheses concerning damages
caused directly or indirectly by ethanol or the major
metabolite acetaldehyde. Current hypotheses include the
direct impact of the free radicals derived by ethanol;
ethanol’s ability to generate formation of oxygen free
radical species, which are able to start lipid peroxidation
either directly or by exhausting antioxidative defense
substances; and acetaldehyde’s ability to stimulate lipid
peroxidation either directly through free-radical forma-
tion or through depletion of the concentration of antioxi-
dative substances [23]. The weak correlation seems in
accordance with Vendemiale et al. [24]: increased plasma
concentrations of glutathione and MDA after acute etha-
nol ingestion in humans (although our parameters are
based on total consumption during 1 week before the
blood sampling). Adjustment of the correlation analysis
for smoking, by “number of daily smoked cigarettes,” did
not change the outcome.
plasma of cigarette smokers [Tech Brief]. Clin Chem 1990;36:
1849–50.
. Sinnhuber RO, Yu TC, Yu TC. Characterization of the red pigment
formed in the 2-thiobarbituric acid determination of oxidative
rancidity. Food Res 1958;23:626–34.
10. Wong SHY, Knight JA, Hopfer SM, Zaharia O, Leach CN, Sunder-
man FW. Lipoperoxides in plasma as measured by liquid-chro-
matographic separation of malondialdehyde–thiobarbituric acid
adduct. Clin Chem 1987;33:214–20.
1. Carbonneau MA, Peuchant E, Sess D, Canioni P, Clerc M. Free and
bound malondialdehyde measured as thiobarbituric acid adduct
by HPLC in serum and plasma. Clin Chem 1991;37:1423–9.
2. Knight JA, Smith SE, Kinder VE, Anstall HB. Reference intervals for
plasma lipoperoxides: age-, sex-, and specimen-related variations.
Clin Chem 1987;33:2289–91.
13. International Federation of Clinical Chemistry (Expert Panel on
Theory of Reference Values) and International Committee for
Standardization in Haematology, Approved recommendation
1
1
(1987) on the theory of reference values. Part 5. Statistical
treatment of collected reference values. Determination of refer-
ence limits. J Clin Chem Clin Biochem 1987;25:645–56; Clin
Chim Acta 1987;170:13–32.
In future studies, P-MDA may be used as a biomarker
of oxidative stress in exposed groups, but smoking and
alcohol consumption should be taken into account as
possible potential confounders.
14. Solberg HE. “REFVAL” Tech. Rep. Oslo: Department of Clinical
Chemistry, Rikshospitalet, 1983.
5. Nair V, Turner GA. The thiobarbituric acid test for lipid peroxida-
1
tion: structure of the adduct with malondialdehyde. Lipids 1984;
19:804–5.
1
6. Gutteridge JMS. Thiobarbituric acid reactivity following iron depen-
The study was funded by the Danish Government by a
grant from The Danish Strategic Environmental Research
Program. The valuable technical assistance of Vibeke
Kvist Pedersen is gratefully appreciated.
dent free-radical to amino acids and carbohydrates. FEBS Lett
1981;128:343–6.
17. Young IS, Trimble ER. Measurement of malondialdehyde in
plasma by high performance liquid chromatography with fluorimet-
ric detection. Ann Clin Biochem 1991;28:504–8.
1
8. Richard MJ, Guiraud P, Meo J, Favier A. High-performance liquid
chromatographic separation of malondialdehyde–thiobarbituric
acid adduct in biological materials (plasma and human cells)
using a commercially available reagent. J Chromatogr 1992;577:
References
1
. Church DF, Pryor WA. Free radical chemistry of cigarette smoke
and its toxicological implications. Environ Health Perspect 1985;
6
4:111–26.
. Halliwell B, Gutteridge JMC. Free radicals in biology and medicine,
nd ed. Oxford: Clarendon Press, 1989:317–21.
. Bridges AB, Scott NA, Parry GJ, Belch JJF. Age, sex, cigarette
smoking and indices of free radical activity in healthy humans. Eur
J Med 1993;2:205–8.
. Kalra J, Chaudhary AK, Prasad K. Increased production of oxygen
free radicals in cigarette smokers. Int J Exp Pathol 1991;72:1–7.
. Brown KM, Morrice PC, Duthie GG. Vitamin E suppresses indexes
of lipid peroxidation and platelet count in blood of smokers and
nonsmokers but plasma lipoprotein concentrations remain un-
changed. Am J Clin Nutr 1994;60:383–7.
. Kamal AAM, Khafif ME, Koraah S, Massoud A, Caillard JF. Blood
superoxide dismutase and plasma malondialdehyde among work-
ers exposed to asbestos. Am J Ind Med 1992;21:353–61.
. Frei B, Forte TM, Ames BN, Cross CE. Gas phase oxidants of
cigarette smoke induce lipid peroxidation and changes in lipopro-
9
–18.
2
3
1
2
2
9. Jiun YS, Hsien LT. Lipid peroxidation in workers exposed to lead.
2
Arch Environ Health 1994;49:256–9.
0. Ross R. The pathogenesis of atherosclerosis—an update. N Engl
J Med 1986;314:488–500.
1. Pryor WA, Church DF, Govindan CK, Crank G. Oxidation of thiols by
nitric oxide and nitrogen dioxide: synthetic utility and toxicological
implications. J Org Chem 1982;47:156–9.
4
5
22. Guemori L, Artur Y, Herbeth B, Jeandel C, Cuny G, Siest G.
Biological variability of superoxide dismutase, glutathione peroxi-
dase, and catalase in blood. Clin Chem 1991;37:1932–7.
23. Dianzani MU. Lipid peroxidation in ethanol poisoning: a critical
reconsideration. Alcohol Alcohol 1985;20:161–73.
24. Vendemiale G, Altomare E, Grattagliano I, Albano O. Increased
plasma levels of glutathione and malondialdehyde after acute
ethanol ingestion in humans. J Hepatol 1989;9:359–65.
6
7