Departments of 1 Pediatrics and 2 Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, Missouri 63110; 3 Departments of Pathology and Pediatrics, University of Texas-Southwestern Medical Center, Dallas, Texas 75235; and 4 Department of Pediatrics, Vanderbilt Children's Hospital, Vanderbilt University, Nashville, Tennessee 37232
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The role of
fat metabolism during human pregnancy and in placental growth and
function is poorly understood. Mitochondrial fatty acid oxidation
disorders in an affected fetus are associated with maternal diseases of
pregnancy, including preeclampsia, acute fatty liver of pregnancy, and
the hemolysis, elevated liver enzymes, and low platelets syndrome
called HELLP. We have investigated the developmental expression and
activity of six fatty acid -oxidation enzymes at various
gestational-age human placentas. Placental specimens exhibited abundant
expression of all six enzymes, as assessed by immunohistochemical and
immunoblot analyses, with greater staining in syncytiotrophoblasts
compared with other placental cell types.
-Oxidation enzyme
activities in placental tissues were higher early in gestation and
lower near term. Trophoblast cells in culture oxidized tritium-labeled
palmitate and myristate in substantial amounts, indicating that the
human placenta utilizes fatty acids as a significant metabolic fuel.
Thus human placenta derives energy from fatty acid oxidation, providing
a potential explanation for the association of fetal fatty acid
oxidation disorders with maternal liver diseases in pregnancy.
acute fatty liver of pregnancy; mitochondria; hemolysis, elevated liver enzymes, and low platelets syndrome
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
BECAUSE THE PLACENTA PROVIDES THE FETUS with nutrients needed for growth and serves as an excretory organ to eliminate wastes from fetal metabolism, placental pathology profoundly affects the developing fetus. The placenta grows exponentially during gestation, from an average of 6 g at 3 wk of gestation to ~470 g at term. Moreover, the villous surface increases from 830 cm2 at 3 wk of gestation to ~125,000 cm2 at term, and the maternal-fetal diffusion distance decreases from 55 to 4.8 mm (16). The placenta requires a constant and abundant source of energy to supply the needs for its own rapid growth and maturation and to transport the nutrients, ions, vitamins, waste, and other molecules required for fetal growth and homeostasis from the maternal to the fetal circulation and vice versa.
A common belief among fetal physiologists (14, 16, 18, 20, 26) is that glucose transported to and across the placenta from the maternal circulation provides all placental and fetal energy needs via glycolysis and the citric acid cycle. Because this supply of glucose is constant, consistent, and reliable, it has been suggested that the placenta and fetus do not need to regulate energy-producing metabolic pathways. The focus of most research has been on transplacental passage of nutrients, including both amino acids and fatty acids, but the metabolic fuel required by the human placenta has not been determined conclusively. The presence of multiple glucose transporters and enzymes of glycolysis and the citric acid cycle in the placenta is consistent with glucose being a major energy source (14). It has been postulated that adequate glucose supply, conversion of acetyl-CoA to malonyl-CoA by acetyl-CoA carboxylase, and the resultant inhibition of carnitine palmitoyltransferase I (CPT I) (26) inhibit fatty acid uptake and oxidation by placental mitochondria in utero (20). Although fatty acids are actively transported across the placenta to the fetus, there are scant data to assess the role of lipids as a metabolic fuel for placental growth and development (18).
Fatty acid oxidation (FAO) defects are autosomal recessive and potentially fatal disorders that are now diagnosed with increased frequency in the perinatal and infantile periods. Uniquely among inherited metabolic defects, FAO enzyme disorders in the affected fetus may cause significant maternal morbidity and mortality (11, 13, 15, 23, 27, 32, 33, 39). We (11, 13, 23) and others (15, 27, 32, 33, 39) have recently shown that maternal acute fatty liver of pregnancy (AFLP), the HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets), placental floor infarction, and preeclampsia are associated with defects in FAO in the fetus. The majority of neonates born after such pregnancies are premature, exhibit growth restriction, and present in the newborn period or early infancy with fasting-induced hypoketotic hypoglycemia and hepatic encephalopathy, which may progress to coma and death (11, 33).
Because FAO disorders in the fetus are associated with maternal
complications and because the human placenta is mostly of fetal origin,
we hypothesized that energy supplied from fatty acid -oxidation in
the placenta could be an important metabolic energy source for
survival, growth, and function in both the placenta and the fetus. As a
corollary, if FAO were active in the placenta and because
late-gestation placenta is of fetal origin, fetal defects in this
pathway would generate long-chain fatty acids that could enter the
maternal circulation in levels toxic to the mother. We report here the
developmental expression and activity of six different FAO enzymes of
the mitochondrial
-oxidation spiral in human placenta (Fig.
1): medium-chain acyl-CoA dehydrogenase (MCAD), long-chain acyl-CoA dehydrogenase (LCAD), very-long-chain acyl-CoA dehydrogenase (VLCAD), short-chain
L-3-hydroxyacyl-CoA dehydrogenase (SCHAD), long-chain
L-3-hydroxyacyl-CoA dehydrogenase (LCHAD), and long-chain
3-ketoacyl-CoA thiolase (LKAT). We used immunohistochemistry, Western
blot analysis, enzyme activity measurements, and metabolic flux studies
to demonstrate substantial FAO expression and function of these enzymes
in the human placenta, consistent with our hypotheses.
|
![]() |
METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Placental tissues and cells.
This study was approved by the Human Studies Committee of Washington
University School of Medicine. Placental specimens were collected at
gestational ages ranging from 12 to 43 wk. Tissue was placed in
chilled, buffered saline to remove maternal blood and then snap-frozen
in liquid nitrogen and stored at 80°C or fixed in 10% neutral
buffered formalin solution at 4°C for 24 h before being
processed for paraffin embedding and immunohistochemical studies.
Twenty-eight placental specimens were used for enzyme activity and
Western blot studies. Specimens were divided for analysis into the
following gestational age groups: 12-19 (n = 3),
20-28 (n = 3), 29-34 (n = 5),
35-37 (n = 4), 38 wk (n = 9), and
>40 wk (n = 4). All samples were utilized to measure
enzyme activity, and nine of these samples from 12 to 43 wk of
gestation were used to run Western blots for the six FAO enzymes.
Immunohistochemistry. Term placentas from uncomplicated pregnancies were collected, and 5-µm-thick sections of paraffin-embedded tissue were cut, applied to glass slides, deparaffinized in xylene, and rehydrated in an ethanol gradient. Endogenous peroxidase activity was quenched by incubating the specimens in 3% H2O2 in methanol for 30 min. After equilibration for 5 min in distilled water, the samples were subjected to heat antigen retrieval using citrate buffer (pH 6.0). The samples were heated at maximum power in a microwave for 5 min, cooled for 5 min, reheated for 5 min, and allowed to stand at room temperature for 20 min.
The slides were then washed and blocked using an avidin-biotin blocking kit (Vector Labs, Burlingame, CA) for 30 min followed by a blocking buffer (NEN-Life Sciences, Boston, MA) for 30 min. The blocking buffer was removed, and the sections were exposed to primary rabbit polyclonal antisera raised against one of the following enzymes at the indicated dilution: MCAD (1:200), LCAD (1:400), VLCAD (1:200), SCHAD (1:200), LCHAD (1:400), LKAT (1:400), or humanWestern blot analyses. Placental tissue freed of maternal blood (100-250 mg) was lysed in a buffer containing 0.1 M sodium phosphate, 0.5 mM EDTA, and 0.5% Triton with protease inhibitors by means of a polytron. The placental lysate was sonicated three times for 10 s each on ice. The lysates were subjected to centrifugation at 3,000 g for 5 min, and the protein concentration of the supernatant was measured by the Bradford method. Fifty micrograms of protein were analyzed by immunoblotting with rabbit polyclonal antisera raised against one of the six different FAO spiral enzymes at the following dilutions: MCAD (1:1,000), LCAD (1:5,000), VLCAD (1:500), SCHAD (1:5,000), LCHAD (1:3,000), and LKAT (1:2,000). Incubation with secondary antibody (goat anti-rabbit, 1:1,000 dilution) and visualization with diaminobenzidine reagent were done until the protein bands were visible. Two to five blots were prepared for each enzyme, and a representative immunoblot was analyzed with an AlphaImager 3400 (Alpha Innotech, San Leandro, CA) using its AlphaEase image analysis software for densitometry. Densitometry data were subjected to statistical analysis to determine any relationship of gestational age to antigen expression.
Enzyme kinetics and metabolic flux studies.
The activities of SCHAD, LCHAD, and LKAT in placental homogenates were
measured as described (3, 35, 38). Trophoblast cells were
harvested from four uncomplicated term pregnancies, and three
75-cm2 flasks from each placenta were used for experiments.
Metabolic flux studies were performed using tritiated water
released from [9,10-3H]palmitate and
[9,10-3H]myristate in 24-well microplates (22,
24). The cells were grown for 20 h while being incubated
with 22 µM [9,10-3H]palmitate or 110 µM
[9,10-3H]myristate, respectively. Each experiment was run
in triplicate, and in all assays, palmitic or myristic acids were
complexed with defatted bovine serum albumin (0.45 mg/ml). By use of
these tritium-labeled substrates, where 3H is distributed
equally between two adjacent carbon atoms, 75-100% of the label
is converted to 3H2O during complete
-oxidation cycle in intact cytotrophoblast cells (22, 24,
36).
Statistical analyses.
We made three enzyme activity measurements from each sample and
compared a total of 28 samples with one another after categorizing them
into gestational age groups; we used multivariate analysis of variance
(MANOVA) with calculation of Wilk's and P values. Data
were later subjected to Student-Newman-Keuls post hoc analysis for
multiple comparisons using statistical software SPSS for PC, version
11.01.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
FAO pathway.
Figure 1 shows the metabolic pathway of entry of fatty acids into the
cell and their breakdown through the mitochondrial -oxidation spiral. Among the six enzymes of the spiral studied here, the highly
homologous enzymes MCAD, LCAD, and VLCAD catalyze the first step by
using substrates of differing chain lengths. SCHAD and LCHAD, which are
also highly homologous, catalyze the second and third reaction of the
spiral, and LKAT performs the final cleavage step in this pathway.
Immunohistochemistry.
We examined expression of these six enzymes by immunohistochemistry in
2-5 term human placentas (Fig. 2).
Minimal nonspecific background staining was observed in control
sections processed without primary antibody (Fig. 2A). After
incubation with -HCG antibody as a positive control (Fig.
2B), intense staining of the syncytiotrophoblast layer was
observed and, as expected, there was no reaction in cells from the rest
of chorionic villi. Figure 2, C-H, shows immunoreactivity
for MCAD, SCHAD, LKAT, VLCAD, LCAD and LCHAD, respectively. The
intensity of staining for all six enzymes was highest in
syncytiotrophoblast and similar to that of
-HCG, suggesting abundant
expression of all FAO enzymes. No specific immunoreactivity for any FAO
enzyme was detected in the chorionic villous vessels or connective
tissue. Although the highest levels of FAO enzyme immunoreactivity were
in the syncytiotrophoblast layer of the chorionic villi, there was also
detectable expression of all FAO enzymes in the villous
cytotrophoblasts. These results show abundant and cell type-specific
expression of the FAO enzymes in both syncytiotrophoblast and
cytotrophoblast but not in core cells of the villi.
|
Expression and activity of FAO enzymes during human placental
development.
Figure 3 is a composite immunoblot to
analyze expression of the six FAO enzyme antigens in placental villi by
use of specimens from between 12 and 43 wk of gestation. Densitometric
analysis of immunoblots indicated that expression of LCHAD, VLCAD, and SCHAD was 2- to 2.5-fold higher at the lower gestational ages of 12 and
17 wk compared with term placenta. LKAT expression was four- and
threefold higher at 12 and 17 wk of gestation, respectively, compared
with term placenta. Our multivariate regression analysis found an
inverse correlation between expression of LCHAD, SCHAD, VLCAD, and LKAT
with gestational age (R2 = 0.65, 0.75, 0.51, and 0.73 for LCHAD, SCHAD, VLCAD, and LKAT, respectively). The
slope of regression was significantly different from zero for LCHAD,
SCHAD, VLCAD, and LKAT, with P values of 0.008, 0.002, 0.02, and 0.002, respectively. There was no measurable difference among
various gestational ages for MCAD and LCAD expression. Figure
4 shows LCHAD, SCHAD, and LKAT enzyme
activities measured from extracts of 28 placental samples. The specific
activities (nmol · min1 · mg
tissue
1) were significantly higher for all three enzymes
at lesser gestational ages (12-28 wk) compared with term placentas
with MANOVA, with Wilk's
of 0.290 and P value of 0.02. Groupwise comparisons using the Student-Newman-Keuls test showed a
significantly higher activity of LCHAD and LKAT at 12-28 wk of
gestation compared with term and postterm placentas and a significantly
higher activity of SCHAD at 12-19 wk compared with term placentas.
These results show that enzymatic activities are regulated during the
course of placental development.
|
|
Tissue-specific activities of FAO enzymes. We compared the enzyme activities of LCHAD, SCHAD, LKAT, and CPT II in fresh, crude, placental tissue extracts with our previously published data of activities in fresh human liver and skeletal muscle extracts and from cultured fibroblasts from normal individuals (2, 3, 38). The enzyme activities in placenta were two- to fivefold less than in liver throughout gestation. Compared with skeletal muscle, both LCHAD and LKAT, components of trifunctional protein that utilize long-chain substrates, were similar or higher in placental extracts from 12- to 19-wk-gestation pregnancies. FAO enzyme activities in crude placental extract were comparable to those in cultured human fibroblasts, but freshly isolated cytotrophoblasts from term pregnancies had substantially greater (2- to 8-fold) LCHAD, SCHAD, and LKAT activities than cultured fibroblasts. The enzyme activities in term trophoblast cells in primary culture were two- to threefold greater than those in fresh placental tissue from term pregnancies. These data show that placenta contains levels of FAO enzymes comparable to those present in mature, fatty acid-dependent tissues such as skeletal muscle, especially between 12 and 19 wk of gestation, and that cytotrophoblasts contain long-chain activities (LKAT and LCHAD) comparable to those of liver.
Fatty acid flux in term human cytotrophoblast cells in culture.
Table 1 shows the results of metabolic
flux studies in cytotrophoblasts with tritiated palmitic acid or
myristic acid as substrates. Primary trophoblast cells cultured for
36-48 h used the two fatty acids as metabolic fuel, with overall
oxidation of fatty acids 30-100% greater than fibroblasts in
culture (P < 0.05).
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Our results show that expression and activities of FAO enzymes as
well as overall FAO of palmitate and myristate are substantial in human
placental villi during gestation and identify trophoblast components as
the primary FAO sites in the term placenta. Expression of FAO enzymes
and measured activities at lower gestational ages of 12-28 wk are
comparable to that in mature slow skeletal muscle, a tissue that uses
fatty acids as a substrate to satisfy high energy requirements. The
data provide direct evidence that fatty acids undergo extensive
mitochondrial -oxidation in the placenta. Our major conclusion is
that fatty acids are utilized as a significant metabolic fuel and
energy source in this organ, consistent with our hypothesis. This
overall conclusion is novel and at variance with the current concept
that glucose is the sole energy source in the placenta (14,
16). On the basis of this conclusion, we speculate that human
placental mitochondrial FAO is critical for normal growth and
maturation of the placenta and for fueling the energy-consuming
functions of ion, nutrient, and waste transplacental transport.
Our study's limitations include a lack of correlation between our in vitro data and in vivo FAO in the fetal-placental unit and some discrepancy between our Western blot and enzyme activity data. We are also limited by the fact that we used term normal placenta to extract trophoblast cells, and our metabolic flux data cannot be applied directly to trophoblast cells from earlier gestations. Thus our in vitro data need to be correlated with in vivo experiments, preferably in human subjects. FAO has been studied in humans by use of 13C-labeled stable isotope technology, and a similar study model can be applied to pregnant women to elucidate our hypothesis more conclusively.
Our metabolic flux data for palmitate and myristate in Table 1 have
high standard deviations, indicating variability in results. Variability among primary cultures is not uncommon, and trophoblast cells are no exception. Our comparison between fibroblasts, a well-studied approach to quantification of fatty acid oxidation in
humans with suspected FAO disorders, and trophoblasts showed no
statistical difference; the major conclusion from these studies is that
trophoblasts indeed oxidize fatty acids. Because all cell lines were
cultured in media containing glucose and not in physiological conditions present in vivo during fasting, we have shown that significant metabolic flux through the FAO pathway occurs even when
glucose is the available energy substrate source. Our previous data in fibroblasts show that, when fatty acids are supplied as substrate, expression of FAO enzymes and flux through the -oxidation pathway increases. Thus the flux measurement presented in Table 1
represents minimal values.
Previous studies are consistent with our conclusion that fatty acid
uptake and metabolism are prominent in placenta. Lipoprotein lipase is
highly expressed on the maternal surface of the syncytiotrophoblast and
hydrolyzes maternal plasma triacylglycerol (17, 29). This enzyme activity would make long-chain free fatty acids available for
uptake. Maternal triglyceride levels rise two- to threefold in late
gestation, thereby increasing availability of fatty acids for uptake
and metabolism (10, 17). Fatty acid-binding proteins that
are critical for uptake of free long-chain fatty acids are also located
on the microvillous membranes of the syncytiotrophoblasts facing the
maternal circulation (1, 4, 5). This location favors
unidirectional flow of maternal fatty acids into the placenta. Furthermore, the VLDL/apolipoprotein E receptor is positioned on the
microvillous surface in human placental trophoblast cells, consistent
with a role in placental lipid uptake and transport (40).
Perhaps most importantly, carnitine, an essential factor for transfer
of long-chain fatty acids from the cytosol to mitochondria for
subsequent -oxidation, is actively transported across the placenta
by an organic cation/carnitine, sodium-dependent transporter (OCTN2)
that is highly expressed in placental tissue (37). Thus previously reported results, in conjunction with our data, strongly suggest that the human placenta is capable not only of transporting fatty acids to the fetus but also of using them as a metabolic fuel.
Our major conclusion has important implications for understanding the
known association of maternal liver diseases of pregnancy, AFLP, HELLP
syndrome, placental floor infarction, and preeclampsia, with LCHAD or
complete trifunctional protein deficiency in the fetus (11, 13,
15, 23, 27, 32, 33, 39). We (11, 13, 23) and others
(33, 34) have shown that pregnancies carrying an affected
fetus with the missense mutation G1528C in the -subunit of
mitochondrial trifunctional protein, a mutation that occurs in the
active site of the LCHAD enzyme, have one of these maternal
complications 75% of the time. This mutation is relatively common
among individuals of northern European ancestry (11, 33),
with a carrier frequency of 1 in 175 in the United States and 1 in 680 in the Netherlands (8). In LCHAD deficiency, accumulation
of the long-chain hydroxyacylcarnitines, free plasma hydroxy-long-chain fatty acids, and dicarboxylic acids occurs. These
metabolites are cytotoxic because they inhibit mitochondrial FAO
enzymes, uncouple oxidative phosphorylation, and impair ATP production
(7, 28, 30, 31). Long-chain acylcarnitines are also known
to damage isolated canine myocyte sarcolemmal membranes and potentiate
free-radical-induced lipid membrane peroxidative injury in
ischemia (21).
We previously postulated (11) that long-chain fatty acids and their metabolites cause maternal liver damage in AFLP and other maternal liver diseases. However, we were puzzled, because the source of the postulated toxic metabolites was unclear given that the fetus does not utilize fatty acids for energy production. The data presented here provide a likely explanation of the seemingly conflicting clinical findings, that is, that the LCHAD-deficient fetal-derived placenta may be the source of these harmful metabolites, particularly as the placental mass and energy requirements increase substantially during the third trimester. In addition to direct toxicity, contributing factors to maternal liver disease might be the 50% decrease in maternal hepatic long-chain fatty acid oxidation capacity related to maternal heterozygosity for LCHAD mutations and the increased liberation of fatty acids during the latter half of pregnancy due to increased lipoprotein lipase and increased reliance on fat as an energy source by the mother late in gestation. Thus we suggest that the placental FAO defect causes maternal liver disease in families with LCHAD or trifunctional protein (TFP) mutations.
A second implication of our findings is that placental insufficiency
due to lack of energy production in pregnancies with FAO-deficient
fetuses may occur. We (11, 13) and others (15, 27,
32, 33, 39) have noted that fetal growth restriction and
prematurity are common among LCHAD-affected fetuses. In addition, we
have shown that ablation of the trifunctional protein -subunit in
mice causes intrauterine growth restriction and perinatal lethality (12). Moreover, in VLCAD- and LCAD-deficient mice,
late-gestation prenatal fetal death is common, despite the fact that
the fetus does not rely on
-oxidation for energy (Exil VJ, Sims HF,
Qin W, Roberts R, Rinaldo P, Zimmerman F, and Strauss AW, unpublished observations; 19). These results are all consistent with
the hypothesis we posed: that placental FAO is critical for the health
of the fetal-placental-maternal unit.
Other FAO defects may also be associated with maternal liver disease but only rarely. Single case reports of maternal liver diseases occurring during pregnancies with fetuses affected by CPT I and SCAD deficiency exist (15, 28). Three cases of maternal liver disease during pregnancies carrying fetuses with complete trifunctional protein deficiency have also been published (6). However, among families with MCAD deficiency, the commonest FAO disorder, and VLCAD deficiency, maternal liver diseases of pregnancy are extremely rare. This raises the possibility that 3-hydroxy- and other long-chain fatty acids that must accumulate in isolated LCHAD or complete TFP deficiencies are particularly toxic.
A second conclusion from our results is that FAO enzymes are expressed
in a cell-specific manner within the placenta and that there is some
developmental regulation of expression during gestation. Trophoblast
cells from term placenta express key enzymes of the -oxidation
spiral, and expression was higher in the synctiotrophoblast layer than
in the cytotrophoblasts (Fig. 2). The syncytiotrophoblast layer of
chorionic villi plays an important role in the uptake of lipids, ions,
and glucose into the placenta and their transfer to the fetus
(17, 29), functions consistent with a large energy requirement. Our measurements revealed modestly higher enzyme activities at lower gestational ages (Fig. 4), emphasizing a key role
for FAO early during gestation.
In summary, we have demonstrated the expression and activity of six
enzymes involved in the FAO -oxidation spiral in human placenta,
with enzyme expression in a cell-specific manner localized to the
syncytiotrophoblast layer, with lesser activity in the cytotrophoblast
cells, and with no expression in villous core cells. Fatty acids are
used as a major metabolic fuel by human placentas at all gestational
ages, and any defect within this energy-producing pathway may hamper
the growth, differentiation, and function of the placenta, thereby
compromising fetal growth.
Defects of FAO in the fetal-placental unit are associated with accumulation of abnormal metabolic precursors, including hydroxyacylcarnitines and dicarboxylic acids. Such toxic fatty acids are likely transferred to the maternal circulation and may contribute to the pathophysiology of preeclampsia, AFLP, and HELLP syndrome in these families.
![]() |
ACKNOWLEDGEMENTS |
---|
We gratefully acknowledge the help of Dr. Beverly Rogers with enzyme kinetics analysis, Karen Hutton with immunohistochemistry, and Prof. James K. Dias from the Medical College of Georgia for statistical data analysis.
![]() |
FOOTNOTES |
---|
This study was supported in part by Grants P30-DK-52574, AM-20407, and DK-02574 from the National Institutes of Health.
Address for reprint requests and other correspondence: P. Shekhawat, Dept. of Pediatrics, Section of Neonatology, BIW 6033E, Medical College of Georgia, Augusta, GA 30912 (E-mail: Pshekhawat{at}mail.mcg.edu).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
First published February 11, 2003;10.1152/ajpendo.00481.2002
Received 5 November 2002; accepted in final form 6 February 2003.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Abumrad, N,
Harmon C,
and
Ibrahimi A.
Membrane transport of long-chain fatty acids: evidence for a facilitated process.
J Lipid Res
39:
2309-2318,
1998
2.
Bennett, MJ,
Spotswood SD,
Ross KF,
Comfort S,
Koonce R,
Boriack RL,
Ijlst L,
and
Wanders RJ.
Fatal hepatic short-chain L-3-hydroxyacyl-CoA dehydrogenase deficiency: clinical, biochemical, and pathological studies on three subjects with this recently identified disorder of mitochondrial -oxidation.
Pediatr Dev Pathol
2:
337-345,
1999[ISI][Medline].
3.
Bennett, MJ,
Weinberger MJ,
Kobori JA,
Rinaldo P,
and
Burlina AB.
Mitochondrial short-chain L-3-hydroxyacyl-CoA dehydrogenase deficiency: a new defect of fatty acid oxidation.
Pediatr Res
39:
185-188,
1996[Abstract].
4.
Campbell, FM,
Bush PG,
Veerkamp JH,
and
Dutta-Roy AK.
Detection and cellular localization of plasma membrane-associated and cytoplasmic fatty acid-binding proteins in human placenta.
Placenta
19:
409-415,
1998[ISI][Medline].
5.
Campbell, FM,
Taffese S,
Gordon MJ,
and
Dutta-Roy AK.
Plasma membrane fatty-acid-binding protein in human placenta: identification and characterization.
Biochem Biophys Res Commun
209:
1011-1017,
1995[ISI][Medline].
6.
Chakrapani, A,
Olpin S,
Cleary M,
Walter JH,
Wraith JE,
and
Besley GTN
Trifunctional protein deficiency: three families with significant maternal hepatic dysfunction in pregnancy not associated with the E474Q mutation.
J Inherit Metab Dis
23:
826-834,
2000[ISI][Medline].
7.
Corkey, BE,
Hale DE,
Glennon MC,
Kelly RI,
Coates PM,
Kilpatrick L,
and
Stanley CA.
Relationship between unusual hepatic acyl-CoA profiles and pathogenesis of Reye syndrome.
J Clin Invest
82:
782-788,
1988[ISI][Medline].
8.
Den Boer, MEJ,
Ijlst L,
Wijburg FA,
Oostheim W,
Van Werkhoven MA,
Van Pampus MG,
Heymans HSA,
and
Wanders RJA
Heterozygosity for the common LCHAD mutation (1528GC) is not a major cause of HELLP syndrome and prevalence of the mutation in the Dutch population is low.
Pediatr Res
48:
151-154,
2000
10.
Herrera, E.
Metabolic adaptations in pregnancy and their implications for the availability of substrates to the fetus.
Euro J Clin Nutr
54, Suppl1:
S47-S51,
2000[ISI][Medline].
11.
Ibdah, JA,
Bennett MJ,
Rinaldo P,
Zhao Y,
Gibson B,
Sims HF,
and
Strauss AW.
A fetal fatty-acid oxidation disorder as a cause of liver disease in pregnant women.
N Engl J Med
340:
1723-1731,
1999
12.
Ibdah, JA,
Paul H,
Zhao Y,
Binford S,
Borgerink H,
Salleng K,
Cline M,
Matern D,
Bennett MJ,
Rinaldo P,
and
Strauss AW.
Lack of mitochondrial trifunctional protein in mice causes neonatal hypoglycemia and death.
J Clin Invest
107:
1403-1409,
2001
13.
Ibdah, JA,
Zhao Y,
Viola J,
Gibson B,
Bennett MJ,
and
Strauss AW.
Molecular prenatal diagnosis in families with fetal mitochondrial trifunctional protein mutations.
J Pediatr
138:
396-399,
2001[ISI][Medline].
14.
Illsey, NP.
Glucose transporters in the human placenta.
Placenta
21:
14-22,
2000[ISI][Medline].
15.
Innes, AM,
Seargeant LE,
Balachandra K,
Roe CR,
Wanders RJA,
Ruiter JPN,
Casiro O,
Grewar DA,
and
Greenberg CR.
Hepatic carnitine palmitoyltransferase I deficiency presenting as maternal illness in pregnancy.
Pediatr Res
47:
43-45,
2000
16.
Kaufmann, P,
and
Scheffen I.
Placental development.
In: Fetal and Neonatal Physiology, , edited by Polin RA,
and Fox F.. New York: Saunders, 1999, p. 47-56.
17.
Kimura, RE.
Lipid metabolism in the fetal-placental unit.
In: Principals of Perinatal-Neonatal Metabolism (2nd ed.), edited by Cowett RM.. New York: Springer Verlag, 1998, p. 389-402.
18.
Knoop, RH,
Warth MR,
and
Charles D.
Lipoprotein metabolism in pregnancy, fat transport to the fetus and the effects of diabetes.
Biol Neonate
50:
297-317,
1986[ISI][Medline].
19.
Kurtz, M,
Rinaldo P,
Rhead WJ,
Tian L,
Millington DS,
Vockley J,
Hamm DA,
Brix AE,
Lindsey JR,
Pinkert CA,
O'Brien WE,
and
Wood PA.
Targeted disruption of mouse long-chain acyl-CoA dehydrogenase gene reveals crucial roles for fatty acid oxidation.
Proc Natl Acad Sci USA
95:
15592-15597,
1998
20.
Loftus, TM,
Jaworsky DE,
Frehywot GL,
Townsend CA,
Ronnett GV,
Lane MD,
and
Kuhajda FP.
Reduced food intake and body weight in mice treated with fatty acid synthase inhibitors.
Science
288:
2379-1381,
2000
21.
Mak, IT,
Kramer JH,
and
Weglicki WB.
Potentiation of free radical-induced lipid peroxidation injury to sarcolemmal membranes by lipid amphiphiles.
J Biol Chem
261:
1153-1157,
1986
22.
Manning, NJ,
Olpin SE,
Pollitt RJ,
and
Webley J.
A comparison of [9,10-3 H] palmitic and [9,10-3 H]myristic acids for the detection of defects of fatty acid oxidation in intact cultured fibroblasts.
J Inherit Metab Dis
13:
58-68,
1990[ISI][Medline].
23.
Matern, D,
Shehata BM,
Shekhawat P,
Strauss AW,
Bennett MJ,
and
Rinaldo P.
Placental floor infarction complicating the pregnancy of a fetus with long chain 3-hydroxy-acyl-CoA dehydrogenase deficiency.
Mol Genet Metab
72:
265-268,
2001[ISI][Medline].
24.
Moon, A,
and
Rhead WJ.
Complementation analysis of fatty acid oxidation disorders.
J Clin Invest
79:
59-64,
1987[ISI][Medline].
25.
Nelson, DM,
Johnson RD,
Smith SD,
Anteby EY,
and
Sadovsky Y.
Hypoxia limits differentiation and up-regulates expression and activity of prostaglandin H synthase 2 in cultured trophoblast from term human placenta.
Am J Obstet Gynecol
180:
896-902,
1999[ISI][Medline].
26.
Prip Buus, C,
Pegorier JP,
Duee PH,
Kohl C,
and
Girard J.
Evidence that the sensitivity of carnitine palmitoyltransferase I to inhibition by malonyl-CoA is an important site of regulation of hepatic fatty acid oxidation in the fetal and newborn rabbit.
Biochem J
269:
409-415,
1990[ISI][Medline].
27.
Schoeman, MN,
Batey RG,
and
Wilcken B.
Recurrent acute fatty liver of pregnancy associated with a fatty-acid oxidation defect in the offspring.
Gastroenterology
100:
544-548,
1991[ISI][Medline].
28.
Tein, I.
Metabolic disease in the fetus predisposes to maternal hepatic complications of pregnancy.
Pediatr Res
47:
6-8,
2000
29.
Thomas, CR,
Lowey C,
and
St. Hillaire RJ.
Studies on the placental hydrolysis and transfer of lipids to the fetal guinea pig.
In: Fetal Nutrition, Metabolism and Immunology: The Role of the Placenta, edited by Miller RK,
and Tiede HA.. New York: Plenum, 1984, p. 135-146.
30.
Tonsgard, JH.
Serum dicarboxylic acids in patients with Reye syndrome.
J Pediatr
109:
440-445,
1986[ISI][Medline].
31.
Tonsgard, JH,
and
Getz GS.
Effect of Reye's syndrome serum on isolated chinchilla liver mitochondria.
J Clin Invest
76:
816-825,
1985[ISI][Medline].
32.
Treem, WR,
Rinaldo P,
Hale DE,
Stanley CA,
Millington DS,
Hyams JS,
Jackson S,
and
Turnbull DM.
Acute fatty liver of pregnancy and long-chain 3-hydroxyacyl-CoA deficiency.
Hepatology
19:
339-345,
1994[ISI][Medline].
33.
Tyni, T,
Ekholm E,
and
Pihko H.
Pregnancy complications are frequent in long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency.
Am J Obstet Gynecol
178:
603-608,
1998[ISI][Medline].
34.
Tyni, T,
Palotie A,
Viinikka L,
Valanne L,
Salo MK,
Dobeln U,
Jackson S,
Wanders R,
Vanizelos N,
and
Pihko H.
Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency with the G1528C mutation: clinical presentation of thirteen patients.
J Pediatr
130:
67-76,
1997[ISI][Medline].
35.
Venizelos, S,
Ijlst L,
Wanders RJA,
and
Hagenfeldt L.
-Oxidation enzymes in fibroblasts from patients with 3-hydroxydicarboxylic aciduria.
Pediatr Res
36:
111-114,
1994[Abstract].
36.
Wanders, RJA,
Ijlst L,
Poggi F,
Bonnefont JP,
Munnich A,
Brivet M,
Rabier D,
and
Saudubray JM.
Human trifunctional protein deficiency: a new disorder of mitochondrial fatty acid -oxidation.
Biochem Biophys Res Commun
188:
1139-1145,
1992[ISI][Medline].
37.
Wang, Y,
Ye J,
Ganapathy V,
and
Longo N.
Mutations in the organic cation/carnitine transporter OCTN2 in primary carnitine deficiency.
Proc Natl Acad Sci USA
96:
2356-2360,
1999
38.
Weinberger, MJ,
Rinaldo P,
Strauss AW,
and
Bennett MJ.
Intact -subunit is required for membrane-binding of human mitochondrial trifunctional
-oxidation protein, but is not necessary for conferring 3-ketoacyl-CoA thiolase activity to the
-subunit.
Biochem Biophys Res Commun
209:
47-52,
1995[ISI][Medline].
39.
Wilcken, B,
Leung K-C,
Hammond J,
Kamath R,
and
Leonard JV.
Pregnancy and fetal long-chain 3-hydroxyacyl-CoA deficiency.
Lancet
341:
407-408,
1993[ISI][Medline].
40.
Wittmaack, FM,
Gafvels ME,
Bronner M,
Matsuo H,
McCrae KR,
Tomaszewski JE,
Robinson SL,
Strickland DK,
and
Strauss JF.
Localization and regulation of the human very low density lipoprotein/apolipoprotein-E receptor: trophoblast expression predicts a role for the receptor in placental lipid transport.
Endocrinology
136:
340-348,
1995[Abstract].