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Human placental lipid metabolism
Human placental lipid metabolism II. Analysis of fatty acids from placentas after intrauterine death
ALEX ROBERTSON, M.D. H 0 WAR D SPR ECH ER , P
H .
D.
Columbus, Ohio Analyses of the fatty acid composition of maternal blood and placenta in 3 cases of intrauterine death show that the placenta retains its characteristic fatty acid pattern, indicating that the placenta may be discreet from fetal metabolic control, and that it is not a tissue of passive fatty acid transport.
NoRM A L pregnancies at the time of delivery the maternal and fetal blood show a striking difference in their fatty acid pattern. The fetal blood has a higher concentration of arachidonic acid and a lower concentration of linoleic acid. This difference is especially obvious in the lecithin fraction. 1 We have suggested that this may result from the action of acyl-GPC acyl-transferase which is present in placental tissue 2 and which preferentially utilizes the more unsaturated fatty acids. 3 Placental tissue resembles fetal blood in its fatty acid pattern. 1 This may be explained in three ways: (1) The placenta may govern the fetal fatty acid pattern; (2) the fetus (via the fetal blood) may govern the placental fatty acid pattern; or ( 3) neither governs the other but their similarity merely reflects similar metabolic tendencies in the fetus and the placenta. When intrauterine death occurs, the feto-
placental circulation stops but the maternoplacental circulation continues until the placenta separates from the uterine wall and delivery occurs. Metabolically, the placenta continues to be active after fetal death. This is obvious, for example in steroid metabolism, where placental progesterone synthesis continues after fetal death. 4 If the fetus governs the placental fatty acid patterns, then after fetal death the placenta might be expected to have an altered fatty acid pattern reflecting the maternal lipid pattern or its own metabolic sequences. To study this, maternal blood and placental tissue fatty acids were determined in 3 cases of intrauterine death.
IN
Case report M. S. was a 31-year-old primigravida. After a normal prenatal course, examination at 42 weeks of gestation revealed normal fetal heart tones and rate. Approximately 4 hours later, the patient complained of sharp abdominal pain and was admitted to the hospital in labor. At that time the fetal heart tones were not heard. A 7 pound, 212 ounce term stillborn infant was delivered. The placenta was removed manually and appeared normal, but it was not examined histologically. The autopsy revealed findings consistent with intrauterine asphyxia, cause undetermined. Intrauterine death is estimated by the clinical history to have occurred at approximately 18 hours before delivery. C. S. S. was a 21-year-old, gravida ii, para i, female whose pregnancy was complicated by a urinary tract infection. At about 39 weeks of
From the Department of Pediatrics and Physiological Chemistry, the Ohio State University College of Medicine, and the Children's Hospital Research Foundation. This investigation was supported in part by funds from a Public Health Research Grant, No. HD 0267501, from the National Institute of Child Health and Human Development, and from a Public Health Research Grant, No. HM 0975602, from the National Institute of Arthritis and Metabolism, and by a contract with the Ohio Department of Health, Maternal and Child Health Division.
247
September 15, !%7 Am. J. Obst. & Gynec.
248 Robertson and Sprecher
occurred. At that time the fetal heart tones were no longer heard, and a fetal electrocardiogram showed no evidence of cardiac action. Labor ensued and a 4 pound, 7 ounce stillborn infant was delivered. The infant was edematous with a protuberant abdomen and hepatosplenomegaly. Donor cells were removed from the peritoneal cavity of the fetus but examination of the fetal cardiac blood revealed no donor cells to be present. It was postulated that the donor cells were partially injected in the amniotic cavity and those injected in the fetal peritoneal cavity were not absorbed. The placenta was pale, but no gross abnormality was seen. The microscopic examination of the placenta and membranes revealed amniochorionitis. The cytotrophoblast was slightly increased in amount and the syncytiotrophoblast was weli preserved. Intrauterine death. was estimated, by physical examination and electrocardiographic findings, to have occurred at least 6 hours before delivery.
gestation, she fell at home, following which no further fetal movements were noted. At 40 weeks' gestation she was examined, and fetal death was diagnosed. The following day the membranes ruptured and a normal labor followed. An 8 pound, 2 ounce macerated stillborn baby was delivered. Autopsy revealed evidence of intrauterine asphyxia. The placenta appeared normal on gross examination. Microscopic examination of the placenta revealed an increase in the cytotrophoblast. The syncytial cells were well preserved with some syncytial knot formation. Except for marked engorgement and thrombosis and some infarction of the subchorionic region there was neither significant hyalinization of the villi nor intervillous thrombi. The cellular detail of the placenta was well preserved. It is estimated by clinical history that intrauterine death ocCUlTed 7 days before delivery. J. N. C. was a gravida iii, para ii, Rh-negative mother whose second infant died at 72 hours of age with erythroblastosis. At approximately 32 weeks of gestation, amniocentesis yielded fluid with a high bilirubin content (O.D. greater than 0.20 at 450 mfl wavelength). An intrauterine fetal transfusion was performed. A leak in the catheter below the maternal skin surface was noted at the conclusion of the procedure. The following day fetal tachycardia was noted. Forty-eight hours after the procedure, rupture of the membranes
Methods Maternal venous blood was obtained at the time of delivery. The placenta was im-
mediately placed at 3° C. and perfused as previously described 2 to remove fetal blood. All samples were frozen and stored at -10° C. until time for extraction.
Table I. Area per cent of fatty acid methyl esters from controls and cases of intrauterine death* Fatty acid
ECL
14:0 15:83 16:0 16:1 I 7:25
17:75 18:0
18:1 18:2 20:3 20:4 22:4 22:5 22:5 22:6
w6 w6 w6 w6 w6 w3 w3
Unidentified
Maternal blood Normal(4) 1.3 ± 1.0 :t 29.5 ± 2.9 ± 1.2 ± 0.6 ± 7.7 :t 22.9 ± 17.8 ± 2.0 ± 7.9 ± 2.0 ± 0.9 ± 0.5 ± 1.2 ± 0.7
Stillborn (3)
l.l 0.3 3.3
0.9 0.7 25.4
1.7 0.7
3.0 1.4
0.3 0.6 0.8
Tr 5.7
4.9
0.8 0.3 0.7 0.5 0.2 0.5
25.1 22.2 1.5 8.2 1.4
0.7 0.7 1.9 0.9
Stillborn (3) :t 26.1 :+: 2.5
1.0
:~
0.3
2.4 ± 0.3
0.9 t 12.5 ± 11.5 ± 7.5 ± 4.3 ± 21.2 ± 2.1 ± 1.6 ± 0.5 ± 3.6 ± 1.1
0.3 1.5 2.1 2.5 0.7 3.0 0.7 0.5 0.2 0.9
0.6
3.6 26.7 1.4 2.5 0.8
10.4
11.9
7.8 3.4 24.0 1.8 1.2 0.6 2.8 0.6
*Fat.~ acids are labeled according to their car?on number and number of unsaturated bonds. The figure following w is
the poSitiOn of the first unsaturated bond numbermg from the methyl end of the molecule. The underlined figures represent three unidentified component< expressed as equivalent chain lengths. The italic figures from top to bottom are oleate linoleate, and arachidonate. Normal values are followed by one standard deviation. Experimental values are expressed ,.; average•. Figures in parentheses represent the number of samples.
Volume 99 Numhet· ~
The lipids were extracted from the placenta and blood samples by repeated homogenization with chloroform-methanol solutions. The lipid extract was washed with water and an aliquot removed for preparing the methyl esters. The methyl esters were determined on an F & M Model 810 Gas Chromatograph apparatus (F & M Co., Avondale, Pennsylvania) as previously described. 1 The methyl esters are expressed as area per cent. Results and comment
In Table I, the average fatty acid values of the 3 cases are compared to normal values. 1 In both maternal blood and placental tissue, no individual methyl ester value varied by more than two standard deviations from the normal mean. It is obvious that after intrauterine death the maternal blood and placental fatty acid patterns do not change appreciably. After fetal death the m.aternoplacental circulation continues until placental separation. Metabolic studies 4 as well as histologic examination (see Case reports) reveal that the placenta continues to function
REFERENCES
1. Sprecher, H., and Robertson, A.: In preparation. 2. Robertson, A., and Sprecher, H.: Pediatrics 38: 1028, 1966. 3. Lands, W., and Merkl, L.: J. Bioi. Chern. 238: 898, 1963.
Placental lipid metabolism
249
even after the cessation of the fetop!acental circulation. This exposes the placenta to a fatty acid cornposition quite different frorn fetal blood, especially in the oleate, linoleate, and arachidonate fractions. Therefore, if the fetus governs the placental fatty acid pattern, we might expect changes to occur in the placental tissue after fetal death. The fact that changes do not occur indicates that the placenta governs its own fatty acid pattern and that it is not merely an organ of fatty acid transport. Does the placenta determine the fatty acid pattern of the fetus? The only way to determine this would be to measur.e fetal lipids after clamping the umbilical vessels before feeding and under circumstances in which fetal fatty add mobilization is negligible. To our knowledge these studies have not been performed. The technical assistance of Mrs. Justina Wilcox and Mrs. Tekla Svanks is gratefully aeknowledged.
4. Lurie, A., Reid, D., and Villee, C.: AM. ]. 0BST. & GYNEC. 96: 670, 1966.
410 West lOth Avenue
Columbus, Ohio 43210
ALEX ROBERTSON, M.D. H 0 WAR D SPR ECH ER , P
H .
D.
Columbus, Ohio Analyses of the fatty acid composition of maternal blood and placenta in 3 cases of intrauterine death show that the placenta retains its characteristic fatty acid pattern, indicating that the placenta may be discreet from fetal metabolic control, and that it is not a tissue of passive fatty acid transport.
NoRM A L pregnancies at the time of delivery the maternal and fetal blood show a striking difference in their fatty acid pattern. The fetal blood has a higher concentration of arachidonic acid and a lower concentration of linoleic acid. This difference is especially obvious in the lecithin fraction. 1 We have suggested that this may result from the action of acyl-GPC acyl-transferase which is present in placental tissue 2 and which preferentially utilizes the more unsaturated fatty acids. 3 Placental tissue resembles fetal blood in its fatty acid pattern. 1 This may be explained in three ways: (1) The placenta may govern the fetal fatty acid pattern; (2) the fetus (via the fetal blood) may govern the placental fatty acid pattern; or ( 3) neither governs the other but their similarity merely reflects similar metabolic tendencies in the fetus and the placenta. When intrauterine death occurs, the feto-
placental circulation stops but the maternoplacental circulation continues until the placenta separates from the uterine wall and delivery occurs. Metabolically, the placenta continues to be active after fetal death. This is obvious, for example in steroid metabolism, where placental progesterone synthesis continues after fetal death. 4 If the fetus governs the placental fatty acid patterns, then after fetal death the placenta might be expected to have an altered fatty acid pattern reflecting the maternal lipid pattern or its own metabolic sequences. To study this, maternal blood and placental tissue fatty acids were determined in 3 cases of intrauterine death.
IN
Case report M. S. was a 31-year-old primigravida. After a normal prenatal course, examination at 42 weeks of gestation revealed normal fetal heart tones and rate. Approximately 4 hours later, the patient complained of sharp abdominal pain and was admitted to the hospital in labor. At that time the fetal heart tones were not heard. A 7 pound, 212 ounce term stillborn infant was delivered. The placenta was removed manually and appeared normal, but it was not examined histologically. The autopsy revealed findings consistent with intrauterine asphyxia, cause undetermined. Intrauterine death is estimated by the clinical history to have occurred at approximately 18 hours before delivery. C. S. S. was a 21-year-old, gravida ii, para i, female whose pregnancy was complicated by a urinary tract infection. At about 39 weeks of
From the Department of Pediatrics and Physiological Chemistry, the Ohio State University College of Medicine, and the Children's Hospital Research Foundation. This investigation was supported in part by funds from a Public Health Research Grant, No. HD 0267501, from the National Institute of Child Health and Human Development, and from a Public Health Research Grant, No. HM 0975602, from the National Institute of Arthritis and Metabolism, and by a contract with the Ohio Department of Health, Maternal and Child Health Division.
247
September 15, !%7 Am. J. Obst. & Gynec.
248 Robertson and Sprecher
occurred. At that time the fetal heart tones were no longer heard, and a fetal electrocardiogram showed no evidence of cardiac action. Labor ensued and a 4 pound, 7 ounce stillborn infant was delivered. The infant was edematous with a protuberant abdomen and hepatosplenomegaly. Donor cells were removed from the peritoneal cavity of the fetus but examination of the fetal cardiac blood revealed no donor cells to be present. It was postulated that the donor cells were partially injected in the amniotic cavity and those injected in the fetal peritoneal cavity were not absorbed. The placenta was pale, but no gross abnormality was seen. The microscopic examination of the placenta and membranes revealed amniochorionitis. The cytotrophoblast was slightly increased in amount and the syncytiotrophoblast was weli preserved. Intrauterine death. was estimated, by physical examination and electrocardiographic findings, to have occurred at least 6 hours before delivery.
gestation, she fell at home, following which no further fetal movements were noted. At 40 weeks' gestation she was examined, and fetal death was diagnosed. The following day the membranes ruptured and a normal labor followed. An 8 pound, 2 ounce macerated stillborn baby was delivered. Autopsy revealed evidence of intrauterine asphyxia. The placenta appeared normal on gross examination. Microscopic examination of the placenta revealed an increase in the cytotrophoblast. The syncytial cells were well preserved with some syncytial knot formation. Except for marked engorgement and thrombosis and some infarction of the subchorionic region there was neither significant hyalinization of the villi nor intervillous thrombi. The cellular detail of the placenta was well preserved. It is estimated by clinical history that intrauterine death ocCUlTed 7 days before delivery. J. N. C. was a gravida iii, para ii, Rh-negative mother whose second infant died at 72 hours of age with erythroblastosis. At approximately 32 weeks of gestation, amniocentesis yielded fluid with a high bilirubin content (O.D. greater than 0.20 at 450 mfl wavelength). An intrauterine fetal transfusion was performed. A leak in the catheter below the maternal skin surface was noted at the conclusion of the procedure. The following day fetal tachycardia was noted. Forty-eight hours after the procedure, rupture of the membranes
Methods Maternal venous blood was obtained at the time of delivery. The placenta was im-
mediately placed at 3° C. and perfused as previously described 2 to remove fetal blood. All samples were frozen and stored at -10° C. until time for extraction.
Table I. Area per cent of fatty acid methyl esters from controls and cases of intrauterine death* Fatty acid
ECL
14:0 15:83 16:0 16:1 I 7:25
17:75 18:0
18:1 18:2 20:3 20:4 22:4 22:5 22:5 22:6
w6 w6 w6 w6 w6 w3 w3
Unidentified
Maternal blood Normal(4) 1.3 ± 1.0 :t 29.5 ± 2.9 ± 1.2 ± 0.6 ± 7.7 :t 22.9 ± 17.8 ± 2.0 ± 7.9 ± 2.0 ± 0.9 ± 0.5 ± 1.2 ± 0.7
Stillborn (3)
l.l 0.3 3.3
0.9 0.7 25.4
1.7 0.7
3.0 1.4
0.3 0.6 0.8
Tr 5.7
4.9
0.8 0.3 0.7 0.5 0.2 0.5
25.1 22.2 1.5 8.2 1.4
0.7 0.7 1.9 0.9
Stillborn (3) :t 26.1 :+: 2.5
1.0
:~
0.3
2.4 ± 0.3
0.9 t 12.5 ± 11.5 ± 7.5 ± 4.3 ± 21.2 ± 2.1 ± 1.6 ± 0.5 ± 3.6 ± 1.1
0.3 1.5 2.1 2.5 0.7 3.0 0.7 0.5 0.2 0.9
0.6
3.6 26.7 1.4 2.5 0.8
10.4
11.9
7.8 3.4 24.0 1.8 1.2 0.6 2.8 0.6
*Fat.~ acids are labeled according to their car?on number and number of unsaturated bonds. The figure following w is
the poSitiOn of the first unsaturated bond numbermg from the methyl end of the molecule. The underlined figures represent three unidentified component< expressed as equivalent chain lengths. The italic figures from top to bottom are oleate linoleate, and arachidonate. Normal values are followed by one standard deviation. Experimental values are expressed ,.; average•. Figures in parentheses represent the number of samples.
Volume 99 Numhet· ~
The lipids were extracted from the placenta and blood samples by repeated homogenization with chloroform-methanol solutions. The lipid extract was washed with water and an aliquot removed for preparing the methyl esters. The methyl esters were determined on an F & M Model 810 Gas Chromatograph apparatus (F & M Co., Avondale, Pennsylvania) as previously described. 1 The methyl esters are expressed as area per cent. Results and comment
In Table I, the average fatty acid values of the 3 cases are compared to normal values. 1 In both maternal blood and placental tissue, no individual methyl ester value varied by more than two standard deviations from the normal mean. It is obvious that after intrauterine death the maternal blood and placental fatty acid patterns do not change appreciably. After fetal death the m.aternoplacental circulation continues until placental separation. Metabolic studies 4 as well as histologic examination (see Case reports) reveal that the placenta continues to function
REFERENCES
1. Sprecher, H., and Robertson, A.: In preparation. 2. Robertson, A., and Sprecher, H.: Pediatrics 38: 1028, 1966. 3. Lands, W., and Merkl, L.: J. Bioi. Chern. 238: 898, 1963.
Placental lipid metabolism
249
even after the cessation of the fetop!acental circulation. This exposes the placenta to a fatty acid cornposition quite different frorn fetal blood, especially in the oleate, linoleate, and arachidonate fractions. Therefore, if the fetus governs the placental fatty acid pattern, we might expect changes to occur in the placental tissue after fetal death. The fact that changes do not occur indicates that the placenta governs its own fatty acid pattern and that it is not merely an organ of fatty acid transport. Does the placenta determine the fatty acid pattern of the fetus? The only way to determine this would be to measur.e fetal lipids after clamping the umbilical vessels before feeding and under circumstances in which fetal fatty add mobilization is negligible. To our knowledge these studies have not been performed. The technical assistance of Mrs. Justina Wilcox and Mrs. Tekla Svanks is gratefully aeknowledged.
4. Lurie, A., Reid, D., and Villee, C.: AM. ]. 0BST. & GYNEC. 96: 670, 1966.
410 West lOth Avenue
Columbus, Ohio 43210