Contact microscopic and histochemical studies of the placenta in normal and pathological pregnancy]

The placenta was studied in 70 women: 19 of them had physiological pregnancy and 51 had pregnancy complicated with late toxicosis. Lesions in the placenta have been shown to increase with the growing severity of toxicosis, and compensatory potencies--to decrease. In late toxicosis the expansion of desorganization and reparation in the placenta occurs from the center towards periphery, the peripheral parts playing the role of reserved zones of the placenta, keeping high functional activity.     

Placental leucine aminopeptidase/oxytocinase in maternal serum and placenta during normal pregnancy

Placental leucine aminopeptidase (P-LAP), which is identical with cystine aminopeptidase as oxytocinase, was found to be homologous with rat insulin-regulated membrane aminopeptidase (IRAP) by sequence comparison. In the current study, we determined the P-LAP levels in maternal serum and placenta during healthy pregnancy. P-LAP activities in maternal serum increased with gestation and rose to the peak of 80 IU/ml at 38 weeks of gestation. Northern blot analysis revealed the increase of P-LAP mRNA levels in placenta in the third trimester compared to the first trimester. P-LAP protein and related activities could be detected in the conditioned medium of placental tissue, while they could not be detected in that of human umbilical vein endothelial cells. Immunohistochemically P-LAP was positively stained in the apical membrane of syncytiotrophoblast cells throughout the gestation. These results established the normal range of serum and tissue P-LAP levels during pregnancy and the possible source of serum P-LAP, which will be helpful to elucidate the physiological and clinical roles of P-LAP/oxytocinase/IRAP.     

Favorable course of pregnancy in a patient two years after kidney transplantation]

A 30-year old female underwent kidney transplantation after unsuccessful 3-year dialysis for renal cortex necrosis. Immunosuppression was achieved with cyclosporin followed by azathioprine with prednisone. The patient conceived after 22 months with kidney transplantation. Mild decrease in arterial blood pressure and marked increased in glomerular filtration rate were seen during the first three months of pregnancy. Arterial blood pressure increased but insignificantly at the end of pregnancy. That time, gradual decrease in creatinine clearance was observed. An increase in serum bilirubin and alkaline phosphatase was noted. Pregnancy was terminated by cesarean section on the 38th week. Newborn was female, full-termed, viable, with body weight of 3,300 g. All examined parameters were normalized after delivery. Described case indicates that transplanted kidney functioning during pregnancy is similar to that in healthy women.     

Selenium in placenta predicts birth weight in normal but not intrauterine growth restriction pregnancy

Placental selenium, lead and cadmium concentrations were determined in a group of pregnancies with birth weight appropriate for gestational age and in a group of intrauterine growth restriction cases. Following adjustment for a number of confounding variables, selenium was found to be a significant predictor of newborn weight only in the group of pregnancies with birth weights appropriate for gestational age. Placental lead and cadmium levels were not associated with birth weight in either group.     

Changes in the proportion of free and bound ribosomes in the syncytiotrophoblast of normal human placenta during pregnancy

Samples of normal human placental tissue from the first and second trimester and the end of pregnancy were processed for electron microscopy. The ratio of free to bound ribosomes in the syncytiotrophoblast was determined by the point-counting method in photographs giving a 45,000-fold final magnification. The ratio of free to bound ribosomes was found to be significantly higher at 9-11 weeks than at 6-8 weeks and to be significantly lower at 12-14 weeks than at 9-11 weeks. No significant differences were found between the 12th to 14th week and the 20th to 25th week. These data were compared with the ratio of free to bound ribosomes in different regions of the placenta at the end of pregnancy.     

Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.     

Neuroendocrine aspects of placenta and pregnancy

Placenta plays a central role in the regulation of physiological mechanisms of pregnancy, and in particular is the organ of communication between mother and fetus. This action is also related to its ability to produce hormones, growth factors and cytokines during the progression of pregnancy, and in response to stimuli such as stress and inflammation/infection. In the last years the understanding of the physiological and pathological functions of human placenta revealed the hypersecretion of hormones in presence of gestational diseases and raised the question whether this mechanism is cause of disorders of pregnancy, or part of an adaptive response of placenta to resolve adverse conditions. However, there are evidences indicating that changes of placental hormone secretion may have clinical usefulness, since they are measurable in biological fluids, and may be used as predictive markers or prognostic tools. Of particular interest is the role of corticotropin releasing hormone, urocortins and activins in the maintaining physiological pregnancy and in the pathogenesis of diseases (preterm birth and preeclampsia).     

Isolated symplasts and stromal syncytial buds of the normal human placenta at 6 to 14 weeks of pregnancy

Formation of isolated symplasts (IS) ("deported trophoblast", according to English nomenclature) and stromal syncytial buds (SSB) has been studied in 10 normal patients at pregnancy of 6-14 weeks by means of the indirect immunoperoxidase method. Monoclonal antibodies against beta-subunit of the human chorionic gonadotropin (beta-HCG), serial paraffin slices, stained with hematoxylin-eosin, semithin slices, stained with toluidin blue-pyronine and scanning electron microscopy have been used. A great amount of syncytiotrophoblastic processes and IS, analogous by their structure to syncytiotrophoblast are revealed. Presence of beta-HCG in the syncytiotrophoblast and its absence in the cytotrophoblast are proved. Concentration of beta-HCG in the IS is higher than in the syncytiotrophoblast of the villi. Maximal concentration of beta-HCG in the SSB is described for the first time. The functional role of the IS and SSB is discussed in the system mother-placenta-fetus.     

Eicosanoid production and transfer in the placenta of the diabetic pregnancy

The metabolism of arachidonic acid (AA) and the transfer of its metabolites was determined in in vitro perfused placental tissue from normal pregnancies and those complicated by maternal insulin-dependent diabetes mellitus (IDDM). 14C-labelled AA was recirculated in the fetal circulation for 60 min while 3H-AA was recirculated in the maternal circulation. Placental effluent was subjected to high performance liquid chromatography (HPLC) and analysis of dual-label scintillation counts. Placentae from IDDM pregnancies converted 3-6 times more radiolabelled AA to eicosanoids than did normal placentae. In addition, the transfer of eicosanoids into the opposing circulation was doubled in placentae from IDDM pregnancies compared to normal placentae. The predominant direction of eicosanoid transfer in both groups of placentae was in the fetal-to-maternal direction. The relative amounts of eicosanoids produced was also altered in placentae from IDDM pregnancies. Increased amounts of thromboxane (Tx) B2 and hydroxyeicosatetraenoic acids (HETEs) were present in both circulations of placentae from IDDM pregnancies. Levels of 6-keto prostaglandin F1a (6KPGF1a) were significantly reduced in both circulations in placentae from IDDM pregnancies. Thus, the ratio of TxA2 to PGI2 and the ratio of HETEs to PGI2 were both significantly increased in placentae from IDDM pregnancies. These results suggest an imbalance in eicosanoid production which may be relevant to abnormal placental structure and function in IDDM pregnancies.     

Time course analysis of RNA stability in human placenta

Background  

Evaluation of RNA quality is essential for gene expression analysis, as the presence of degraded samples may influence the interpretation of expression levels. Particularly, qRT-PCR data can be affected by RNA integrity and stability. To explore systematically how RNA quality affects qRT-PCR assay performance, a set of human placenta RNA samples was generated by two protocols handlings of fresh tissue over a progressive time course of 4 days. Protocol A consists of a direct transfer of tissue into RNA-stabilizing solution (RNAlater™) solution. Protocol B uses a dissection of placenta villosities before bio banking. We tested and compared RNA yields, total RNA integrity, mRNA integrity and stability in these two protocols according to the duration of storage.