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PubMed1977

[New aspects in diagnosis and therapy of placental insufficiency. Placental perfusion measurements; placental perfusion test (PPT) and betamimetic long term treatment (clinical and experimental data (authors transl)].

The rate of utero-placental blood flow depends on functional components (perfusion pressure and flow resistance within the area of the vascular bed of the placenta), as well as on morphological factors (regressive changes in the placenta). Different primary maternal conditions and diseases may lower the rate of placental flow, leading to placental insufficiency; the highest percentage, by far, of placental dysfunction is found in patients suffering from gestosis. Hypocirculation initially present in cases of EPH gestosis and caused by arteriolar spasms triggers off a vicious circle involving placental infarction and severe reduction in the utero-placental perfusion rate. This in turn leads to fetal hypotrophy, a high rate of premature births and perinatal mortality. Verification of HPL, HCG, alpha-Fetoprotein or E3 in maternal serum and amniotic fluid or urine greatly improved the recording of partial placental functions. Along with ultrasonic biometry, cardiotocography and amnioscopy, these hormonal parameters allow only indirect assessment of the placental function. On the other hand, measurements of the utero-placental flow offers a direct approach. In order to evaluate the placental flow measurements it is imperative to obtain a curve indicating the course over the last third of the pregnancy-in addition to establishing a general normal range. In case of placental insufficiency, it is necessary to determine whether this is due to functional disorders alone, or to more extenisve morphological changes. A placental perfusion test (PPT) was developed in order to make this distinction. Beta2-mimetic treatment is indicated if functional factors predominate, whereby it appears essential to obtain the requisite experimental data for precise quantification of beta-mimetic action.

Adrenergic beta-Agonists↗
PubMed1977

Plasma human placental lactogen, oxytocinase, and placental phosphatase in normal and toxemic pregnancies.

A total of 625 serum samples were drawn from 400 normal and 225 hypertensive toxemic pregnant women. Each sample was simultaneously assayed for its human placental lactogen (HPL), oxytocinase (O), and placental phosphatase (PP) concentration. In addition, accurate placental and infant birth weights were determined in those cases where the serum sample was obtained within 14 days of delivery. The results showed a significant rise and correlation of each of the three proteins with increasing weeks of gestation. Although the infant birth weight was unrelated to the serum level of the three proteins, both the HPL and O concentrations were significantly correlated with the placental weight in the normal pregnancies. In both types of pregnancies, the concentration of O was significantly related to that of PP and this was also true for HPL and O and HPL and PP. In all instances O was more strongly related than PP. In the toxemic pregnancies there was a higher O and lower PP level than in normal gestations. These data suggest that placental enzyme measurements, especially O, could be clinically helpful in monitoring high-risk pregnancies.

Aminopeptidases↗
PubMed1979

Value of total serum oestriol and human placental lactogen in the assessment of fetal-placental function.

Serum levels of total oestriol and human placental lactogen (HPL) were measured in 360 pregnancies; in 182 there were abnormalities likely to be associated with increased fetal risk. A total of 217 estimations of oestriol and HPL were performed in 163 normal pregnancies to define the normal ranges. The value of both tests in the management of complicated pregnancies was assessed. Serum oestriol was found to be very efficient in the diagnosis of intrauterine growth retardation. In such cases, 76% of patients had unfavourable oestriol levels. Patients with mild pre-eclampsia had HPL levels similar to normal, but values decreased significantly in the presence of fetal distress. The mean serum oestriol level in patients with pre-eclampsia were lower than normal, and were further reduced in the presence of fetal distress. The importance of measuring serum oestriol levels at each antenatal visit is stressed in the detection of developing fetal complications; in such cases, 73% of patients had subnormal values. Both tests provided accurate assessments in the 8 patients with intrauterine death. Significant fetal-placental dysfunction was present in 55 patients, and 41 (75%) were predicted by serum oestriol, 23 (42%) by HPL, and 45 (82%) by the use of both tests. In the 142 complicated pregnancies that resulted in a favourable outcome, confirmation was obtained in 102 (72%) by serum oestriol and in 121 (86%) by HPL.

Adult↗
PubMed1975

Uptake of 125-I-labelled human placental lactogen and human placental lactogen by the tissues of normal and lactating rats.

The rate of clearance from the circulation and uptake into tissues of radioactive label was studied after i.v. injection of 125-I-labelled human placental lactogen (HPL) into rats at various stages of pregnancy. The half-life was obtained for the disappearance of the trichloroacetic acid-precipitable material from the plasma. The half-life, t1/2(S), calculated over the first 5 min after injection of the hormone was 5.4 equals or minus 1.1 (S.D.) min, while a half-life, t1/2(L), of 27.9 equals or minus 2.3 min was obtained from the decay period of 15-35 min. In the non-pregnant and pregnant rat the highest ratio of the radioactivity in an organ to that in the blood was 12-14:1 in the kidney. That the kidney is mainly involved in the uptake of exogenous HPL is further confirmed by the application of the histochemical immunoperoxidase technique. Human placental lactogen was localized in the cells of the proximal tubules of the cortex and to a lesser extent in the tubular lumen and the tubules of the medulla region. UPTAKE OF HPL in vivo occurs in the mammary gland tissue of the post-partum rat and reaches a maximum uptake between 15 and 30 min after injection of the hormone. Furthermore, specific uptake of HPL was observed on the alveolar cell membranes after the incubation of paraffin-embedded sections of formalin-fixed mammary gland and subsequent treatment by the peroxidase-labelled antibody method. These findings support the work of others who have demonstrated the presence of specific membrane receptors in the mammary gland for hormones with prolactin-like activity.

Absorption↗
PubMed1978

Human placental cells transformed by tsA mutants of simian virus 40: a model system for the study of placental functions.

Human placental cells were transformed with wild-type simian virus 40 (SV40) and temperature-sensitive SV40 mutants of the A and B classes. Four criteria for transformation were used: decreased generation time, increased saturation density, increased efficiency of growth on plastic, and ability to overgrow a nontransformed monolayer. Cell lines transformed by tsA mutants lost the transformed phenotype at the restrictive temperature (40 degrees); therefore, the A function of SV40 is required for the maintenance of the transformed phenotype activity, an inhibition of human chorionic gonadotropin synthesis, and an increase in thymidine kinase activity were seen when human placental cells transformed by wild-type or tsB mutants of SV40 were grown at 33 degrees or 40 degrees and when tsA transformants were grown at 33 degrees. When tsA transformants were grown at 40 degrees, alkaline phosphatase activity and human chorionic gonadotropin synthesis were greatly stimulated and thymidine kinase activity was greatly reduced, approximating their levels in the placenta.

Alkaline Phosphatase↗
PubMed1979

Pharmacokinetics of the placental transfer and distribution of clorazepate and its metabolite nordiazepam in the feto-placental unit and in the neonate.

Clorazepate 20 mg was given i.m. to 49 mothers during the first stage of labour. The elimination of the drug was studied in 27 newborns produced by these mothers. The same dose was given to 13 women who underwent amniocentesis and to 7 women who were breast-feeding. "Total nordiazepam", i.e. the sum of clorazepate and its metabolite nordiazepam, was determined by gas-liquid chromatography in maternal blood, umbilical cord blood (both arterial and venous), amniotic fluid and in milk. Clorazepate was found to cross the placental barrier slowly, but nordiazepam was transferred more rapidly. Nordiazepam was found in the milk and in the blood of neonates after breast-feeding had started.

Adult↗
PubMed1977

Dimeric ("big") human placental lactogen. Immunological and biological activity.

Dimeric ("big") human placental lactogen has been isolated in near homogeneous form from placental tissue. It consists of a disulfide-linked (stable) form and a noncovalently associated (unstable) form of the native hormone. The two forms were separated by exposure to denaturing conditions and resolution by gel exclusion chromatography. Both forms retained immunological activity, ability to bind mammary membranes, and ability to induce mammary N-acetyllactosamine synthetase in vitro. On a molar basis, stable dimeric placental lactogen was more active than placental lactogen in the radioimmunoassay indicating that the immunological determinants on both monomeric units could bind to antibody. On a molar basis, stable dimeric placental lactogen was equally active with monomeric placental lactogen in competing for mammary gland membrane binding sites, indicating that only one active site in the molecule could interact with the membrane at a time. Stable dimeric placental lactogen was also active in an in vitro bioassay using the induction of N-acetyllactosamine synthetase. It is concluded that dimer formation does not alter the biologically active portion of the placental lactogen molecule. Since the carboxyl-terminal region (residues 182-191) is involved in the interchain disulfide bonds of dimeric placental lactogen, this portion of the molecule is probably not necessary for its biological activity.

Animals↗
PubMed1979

Lack of homology between dog and human placental alkaline phosphatases.

Alkaline phosphatases [ALPases; orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] from dog and human placenta, liver, bone, kidney, and intestine were investigated by inhibition studies with L-homoarginine, L-phenylalanine, and L-phenylalanylglycyl-glycine; by thermostability studies; and by electrophoresis, both before and after treatment with neuraminidase. The inhibitions obtained for each inhibitor with dog placental ALPase closely match those obtained with dog and human liver, bone, and kidney ALPases, but are quite different from those obtained with human placental ALPase. Dog placental ALPase is thermolabile, as are dog and human liver, bone, and kidney ALPases, in marked contrast to human placental ALPase, which is very thermostable. Dog placental ALPase has the same electrophoretic mobility as dog liver, bone, and kidney ALPases after removal of sialic acid residues with neuraminidase. Desialated human placental ALPase differs electrophoretically from desialated human liver, bone, and kidney ALPases, which show the same mobilities. Dog and human intestinal ALPases are distinguished by these various criteria from the liver, bone, kidney, and placental ALPases of both species, but are similar to each other. These results suggest that the ALPase gene locus expressed in dog placenta is not homologous to that expressed in human placenta. Rather, it appears to be homologous to the ALPase locus expressed in dog and human liver and possibly also bone and kidney. Other incomplete data suggest that this may also be true for placental ALPase in other mammalian species. One possible explanation is that human placental ALPase, a relatively recent newcomer on the evolutionary scene, arose from a gene duplication that occurred subsequent to the evolutionary divergence of many other mammalian species.

Alkaline Phosphatase↗
PubMed1978

Use of immunocytochemical techniques for the localization of human placental lactogen.

The recent claim by Gau and Chard (Br J Obstet Gynaecol 83:876, 1976) that, on theoretical grounds, it may be impossible to demonstrate the presence of human placental lactogen in placental tissue using the immunoperoxidase technique, has been reinvestigated. Placental tissue fragments fixed in Carnoy's fluid retained their morphologic identity compared with tissue fixed in formalin. Using these nonformalin fixed tissues, human placental lactogen was successfully localized within the cytoplasm of the syncytial layer of the placental villus. It is concluded that placental villi at term do in fact contain sufficient human placental lactogen to be demonstrated using the immunoperoxidase technique in contrast to the observation of Gau and Chard.

Female↗
PubMedDate not supplied

Regulation of placental enzymes of the carbohydrate and lipid metabolic pathways.

The activity of enzymes with a regulatory function in the pathways of glycolysis, gluconeogenesis, NADPH generation and fatty acid synthesis was measured in the placenta and liver of rats. Compared with the liver, a high activity of pyruvate kinase was found in the placenta, indicating a high glycolytic potential; a small capacity for gluconeogenesis was also present and a moderate to low activity of enzymes associated with lipogenesis. The activity of all placental enzymes fell from day 15 to 20 of gestation irrespective of the pathway they represented. The pattern of decline continued when the gestation was prolonged up to day 26 by the administration of chorionic gonadotropin. The rates of activity disappearance over 11 days of gestation differed for each enzyme, with half-lives ranging from 2.7 days for NADP-malate dehydrogenase to 7 days for glucose-6-phosphate dehydrogenase. In contrast, the activity of hepatic enzymes either remained unchanged or showed individual adaptation to the advancing pregnancy. The regression in placental metabolic capacity after day 15 of gestation was also evident by the decrease in glucose uptake and its channelling to lactate, CO2, glycerol and fatty acids. In addition, placental ageing was associated with triglyceride accumulation, mainly due to the decrease in free fatty acid oxidation. Treatment of pregnant rats with several hormones, while markedly affecting the hepatic enzyme activities, failed to induce appreciable changes in the corresponding placental enzymes. This was illustrated in the case of triiodothyronine treatment. Similarly, insulin deficiency induced by streptozotocin failed to elicit adaptive changes in placental enzyme activities typical of diabetes like those occurring in the maternal liver; some converse responses in the placenta were attributed to hyperglycaemia. On the other hand, responses in some fetal liver enzymes were suggestive of fetal hyperinsulinaemia. These observations indicate that placental enzymes are not susceptible to endocrine regulation and imply that placental metabolism is largely independent of the physiopathological alterations affecting the maternal organism. The gradual activity decreases with gestation suggest that the enzyme complement of the placenta, once developed, is designed to last through its limited lifespan without continuous replenishment. Within this context, no mechanism seems to operate to ind1ce the adaptive synthesis of individual enzymes, and the age of the placenta appears to be the primary factor determining its enzyme activity and metabolic performance.

Acetyl-CoA Carboxylase↗
PubMed1979

Placental clearance of lactate and bicarbonate in sheep.

To determine the placental clearance of lactate and bicarbonate in sheep, the fetal side of an isolated cotyledon and the umbilical circulation of the total placenta were artificially perfused. The release and uptake of lactate and bicarbonate by the perfusion fluid and the fetomaternal concentration differences of these substances were measured. From these data, the clearance of lactate and bicarbonate was determined to be 0.9 (SE = 0.2) ml/h/g of placental tissue. The production of lactate by the placenta was calculated to be about 30 mumol/min, the placental permeability of lactate was evaluated to be about 1.3 ml/h/g of placental tissue. These results indicate that fetal concentration changes of lactate and bicarbonate due to placental transfer occur with a half time of about 4 h. It is concluded that the lactate and bicarbonate permeability of the syndesmochorial placenta of the sheep is about 20 times smaller than the placental permeability of the hemochorial placenta of the guinea pig. It seems unjustified to draw any conclusions from experimental data obtained in the sheep placenta for the transplacental acid-base balance between mother and fetus in human beings.

Animals↗
PubMed1975

Placental insufficiency in relation to postterm pregnancy and fetal postmaturity. Evaluation of fetoplacental function; management of the postterm gravida.

As pregnancy extends post term, incidence of placental insufficiency, fetal postmaturity (dysmaturity), and fetal perinatal death increases rapidly as a consequence of reduced respiratory and nutritive placental function. Despite a compensatory fetoplacental respiratory reserve capacity, fetal distress is observed in about one third of postterm pregnancies. On a biochemical level, placental pathophysiology in postterm-postmaturity pregnancies is not well understood. Postmaturity is correlated with increased incidence of placental lesions, fetal hypoxia-asphyxia, intrauterine growth retardation, increased perinatal death, and neonatal morbidity. Early diagnosis of fetal postmaturity is difficult because currently applied test methods allow recognition only when placental insufficiency is far progressed. Therefore, in postterm gravidas with a favorable cervix, induction of labor should be considered; in older primigravidas, in whom fetal losses may be sevenfold increased, or in multiparas with a history of obstetric complications, pregnancy may require termination by cesarean section. Pregnancy may be allowed to continue under close supervision in cases of uncertainty of duration of gestation, in gravidas carrying small babies, in young primigravidas, and in multigravidas in whom placentofetal function tests are normal. As long as fetal scalp blood sampling during labor does not show fetal acidosis, despite abnormal fetal heart rate pattern and meconium release, vaginal delivery may be attempted when deemed possible within a few hours. In parturients attention must be paid to the extent of uterine activity and type of medication; lateral positioning of the gravida and maternal oxygen breathing, facilitating fetal oxygen supply, are important features. Because during bearing-down efforts placentofetal respiratory reserves of postterm gravidas may become further compromised, immediate delivery by forceps or vacuum extraction may be considered. After delivery the umbilical cord should not be clamped immediately in order to allow increased fetal blood supply and to counteract fetal hypovolemia. Dysmature newborn infants require special care by the neonatologist.

Adrenocorticotropic Hormone↗
PubMed1979

Primary structure of the NH2-terminal extra piece of the precursor to human placental lactogen.

The cell-free translation product of human placental lactogen mRNA is a precursor molecule larger than the mature hormone that circulates in plasma. To determine the structure of pre-placental lactogen, the poly(A)-rich RNA fraction of term placenta was isolated and translated in a wheat germ cell-free system. The mRNA programmed the synthesis of a major protein, 3000 daltons larger than placental lactogen, that was specifically precipitated by hormone antibodies. The immunoprecipitated protein was labeled separately with 20 radioactive amino acids and subjected to sequence analysis. The results showed the synthesis of pre-placental lactogen in which an extra piece 25 residues long preceded the NH2 terminus of the mature protein. The structure of the extra piece is as follows: Met-Pro-Gly-Ser-Arg-Thr-Ser-Leu-Leu-Ala-Phe-Ala-Leu-Leu-Cys-Leu-Pro-Trp-Leu-Gln-Glu-Ala-Gly-Ala-. Met1 is the initiator residue because only initiator [35S]Met-tRNAMet1, but not internal [35S]Met-tRNA2Met, donated NH2-terminal methionine. The structure of the extra piece showed little homology with that of unrelated hormones but striking homology (64%) with the extra piece of rat pre-growth hormone. Most amino acid substitutions involved a single base change in the codon. Mature human placental lactogen and rat growth hormone have 59% homology in sequence. Thus, our findings provide additional evidence to support the common evolutionary origin of these hormones, not only of the mature proteins but also of the extra piece segments.

Amino Acid Sequence↗
PubMed1979

Circulating levels of pregnancy proteins in early and late pregnancy in relation to placental tissue concentration.

The concentrations of human chorionic gonadotrophin (hCG), human placental lactogen (hPL), pregnancy specific beta 1 glycoprotein (SP1), ferritin (PP2) and placental protein 5 (PP5) were examined in maternal serum and placental tissue in early and late pregnancy. The circulating concentration of hPL, SP1, and PP5 were higher during late pregnancy than early pregnancy, that of hCG lower, and ferritin (PP2) levels showed no difference. Placental tissue levels of hPL and SP1 were higher in late pregnancy, hCG levels lower, and ferritin (PP2) and PP5 showed no change. The ratio of the concentration in maternal serum to that in placental tissue increased during pregnancy for all proteins with the exception of ferritin. It is proposed that the mechanism of secretion of trophoblast specific proteins varies widely and that this should be taken into account in the clinical interpretation of circulating levels in the mother.

Chorionic Gonadotropin↗
PubMed1975

Immunological methods for human placental alkaline phosphatase (Regan isoenzyme).

Four different immunological methods for the determination of the placental isoenzyme of alkaline phosphatase (Regan isoenzyme) were compared in 64 normal blood donors, 23 healthy laboratory and medical staff workers and 68 pregnant women: a. Inhibition by soluble antibodies to the placental enzyme. b. Precipitation with soluble antibodies. c. Precipitation with immobilized antibodies. d. Measurement of the activity of the placental alkaline phosphatase following binding to an immunoabsorbent that has been obtained by polymerization of anti-placental-alkaline phosphatase gamma-globulin using glutaraldehyde. The immunoabsorbent method yielded the best results. The optimal conditions were evaluated for the measurement of the activity of immunoabsorbent-fixed placental (tumoral) alkaline phosphatase activity. This method was applied to 209 normal blood donors and to 239 patients with different malignant tumors: 25.5 percent of the cancer patients exhibited an elevated Regan -isoenzyme activity in the serum.

Alkaline Phosphatase↗