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At least 19 recordsLinked to original sources
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↗
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↗
PubMed1977

Some properties of the goat placental lactogen.

Goat placental lactogen was partially purified from a medium collected after placental tissue incubation. The data obtained by disc electrophoresis and isoelectric focusing experiments, as well as by means of radioreceptor assay methods, provide evidence of the similarity between the goat and ovine placental lactogen.

Animals↗
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↗
PubMed1977

Alteration of human placental lactogen by mammary gland.

Human placental lactogen was prepared in high purity and in good yield applying a minimum of purification steps. The isolated hormone was characterized with respect to isoelectric and electrophoretic properties, molecular size (estimated mol. wt. 23 000) and stability to heat, pH and organic solvents. Investigation of in vitro interaction between placental lactogen and mammary gland (mouse, rat) revealed a rapid alteration of hormone with loss of immunoreactivity resulting. The target organ as a selective alteration site of placental lactogen was suggested by a lack of similar action on the hormone by a number of other tissues tested, including liver, kidney and lung. The reaction involving hormone alteration by mammary gland was localized to a particulate-bound enzyme, sedimentable at 10 000 X g and undissociated by sonication in 0.5% Triton X-100. Examination of the reaction products revealed hormone degradation with formation of diffusible components and loss of original electrophoretic identity as well as immunoreactive properties. The reaction characteristics included: pH optimum between 7.5 and 8.0, an absolute salt requirement (NaCl, KCl, at concentration greater than 0.15 M for maximal activation), inhibition by Cleland's reagent and lack of reaction interference by pituitary prolactin.

Animals↗
PubMed1977

Microheterogeneity of human placental lactogen showing different patterns in individuals.

Samples of human placental lactogen, obtained either as a standard pooled preparation or prepared from individual placentas, were shown to migrate as a single band on acrylamide gel electrophoresis. When subjected to isoelectric focusing in polyacrylamide gels, the pooled sample was resolved into bands at pI values 5.0, 5.5, 5.8. 6.0, 6.1 and 6.2. Different batches of the standard pooled sample gave different proportions of each isoprotein species. Isolation and refocusing of individual bands did not alter the pI of each. Treatment with urea or with p-chloromercuribenzoate did not eliminate microheterogeneity seen on isofucising, indicating that the observed heterogeneity is probably not due to conformational differences or to restriction of molecular shape of disulfide bonds. It was shown by immunodiffusion that all the isofocusing reacted similarly against a common antibody to human placental lactogen. When placental lactogen was extracted from individual full term human placentas, the same isoprotein bands were observed but their proportions varied markedly from one placenta to another, and not all bands were present. Thus human placental lactogen displays considerable microheterogeneity which varies with individual placentas.

Electrophoresis, Polyacrylamide Gel↗
PubMed1977

Immunofluorescent localization of ovine placental lactogen.

The localization of ovine placental lactogen (OPL) was studied using the immunofluorescence method. The placentome sections were treated by an indirect technique with anti-OPL antibodies obtained from rabbits injected with purified hormone. OPL was located in large cells of the monostratified epithelium of chorionic villi. These cells are mono- or binucleated and PAS-positive. The immunological reaction was inhibited by the specific antigen (OPL, 400 microgram/ml undiluted anti-OPL antiserum) but not by ovine prolactin, bovine growth hormone, human placental lactogen nor by any other polypeptidic hormone tested. Reciprocally, the localization of OPL-secreting cells was unsuccessful with antibodies raised against these control hormones.

Animals↗
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

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↗
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↗
PubMed1977

Fetal movements and placental lactogen levels for fetal-placental evaluation. A preliminary report.

Fetal movements were measured by 37 pregnant women during a 10-minute period while they were lying on their left side at various times during the day with the highest rates in the evening. Preliminary assessments of fetal movement and serum hPL levels in pregnant women suggest that the two tests might complement each other in providing more information about the status of the placenta and fetus.

Circadian Rhythm↗
PubMed1978

Maternal serums and amniotic fluid levels of human placental lactogen in gestational diabetes.

Human placental lactogen (hPL) levels were measured radioimmunologically in maternal serum and in amniotic fluid between the 37th and 39th weeks of gestation in sixteen gestational diabetic and thirty normal pregnant women. There was no significant difference in maternal serum hPL levels between diabetic (6.1 microgram/ml) and normal pregnant women (6.4 microgram/ml). In contrast, the diabetic group was found to have significantly (P less than 0.001) higher concentrations of amniotic fluid hPL (1.2 microgram/ml) than normal pregnant women (0.8 microgram/ml).

Amniotic Fluid↗
PubMed1979

A microprocessor-controlled assay for the estimation of human placental lactogen.

A radioimmunoassay for human placental lactogen (HPL) is described using the KEMTEK 3000, which is a modular radioimmunoassay apparatus controlled by a microprocessor. Operation of the KEMTEK 3000 is largely automatic and it requires minimal intervention from the operator. It is capable of 300 reactions per hour so that a large number of estimations can readily be performed. HPL was assayed by a double antibody method on serum samples from pregnant women and patients with trophoblastic tumours.

Antigens↗
PubMed1976

Localization and specificity of binding of subprimate placental lactogen in rabbit tissues.

A search for specific placental lactogen binding was undertaken in tissues obtained from late pregnant rabbits using the placental lactogens from sheep, cows, and human beings. 125I-labeled ovine lactogen exhibited highest specific binding to the adrenal gland (57.8%), followed by liver (21.5%), ovary (19.9%), mammary gland (15.9%), uterus (12.2%), kidney (8.8%), brain (8.5%), and adipose tissue (7.9%). In liver and mammary gland, the displacement curves for ovine and human lactogen were identical to that for bovine prolactin, indicating that they share the same receptor site. Although the displacement curve for bovine lactogen was parallel to that of the other lactogens the bovine hormone is less active in the radioreceptor assay.

Adrenal Glands↗
PubMed1975

The relation of polypeptide hormone structure and flexibility to receptor binding: the relevance of X-ray studies on insulins, glucagon and human placental lactogen.

Thr relevance of the crystal structure of the polypeptide hormones, insulin, glucagon and human placental lactogen to conformation and flexibility in solution and to receptor binding is considered. X-ray studies for crystal forms of glucagon, human placental lactogen and three insulin derivatives (A1 acetyl insulin, A1-t-butoxy carbonyl insulin and A1 2,2-dimethyl-3-formyl-L-thiazolidine-4-carbonyl insulin) are reported. Neither glucagon nor human placental lactogen are as ordered as insulin in the crystal form. Glucagon crystals undergo distinct transformations on changing the pH of the mother liquor from pH 9.5 to pH 6, indicating that the glucagon molecule is flexible in the crystal, as it is in solution. On the other hand all insulin analogues have a similar three dimensional structure to that of native insulin. Three dimensional difference Fourier studies of two insulin derivatives at 3 A resolution indicate the position of the modifying groups and define the small conformational changes which have occurred. The in vitro biological activity and receptor binding decrease with the increasing size of the group added to A1. The correlation of the structure analysis with the biological data strongly implicate a region close to A1 in receptor binding. Insulin appears to bind to the receptor in a specific conformation similar to that observed in the crystal structure and in solution; amino acid residues which are separated in the primary structure but brought into close juxtaposition in the tertiary structure are important for full potency.

Animals↗
PubMed1979

Lactogenic response of mouse mammary explants from different days of pregnancy to placental lactogen and pituitary prolactin.

The lactogenic response of mouse mammary gland explants to human placental lactogen (hPL) and ovine pituitary prolactin (oPRL) was examined on days 10 to 18 of pregnancy by measuring 3H-amino acid incorporation into calcium-rennin precipitable casein. To determine the lactogenic response of the explants, the mean slopes of dose-response curves were calculated for each hormone treatment. Slope means of dose-response curves for oPRL and hPL did not differ from each other on any day of pregnancy examined. A triphasic pattern of response was suggested when slope means of dose-response curves for both hormones were plotted as a function of day of gestation. Peak responses were observed on days 10, 13 and 17-18. Combinations of oPRL and hPL, in ratios of oPRL:hPL = 2:1 and oPRL:hPL = 1:2, also produced a triphasic pattern of sensitivity very similar to that produced by either hormone alone. These results suggest that mouse mammary explants may be more sensitive to oPRL and hPL on days 10, 13 and 17-18 of pregnancy.

Animals↗