Biomedical subjects

V Jansen

Publications and source records attributed to V Jansen.

36 records · Page 2Linked to original sources

PubMed1979

Secretory proteins in the perfused human placenta.

A relatively simple perfusion technique of human placenta has been applied to the study of secretory proteins. Preferential secretion into the maternal circulation of human chorionic gonadotropin (HCG), human chorionic somatomammotropin (HCS), follicle-stimulating hormone (FSH), and placental alkaline phosphatase has been demonstrated, contrasting with the bidirectional secretion of progesterone. Evidence is presented for the net synthesis of HCS during perfusion. The technique offers advantages in the study of synthesis and secretion of placental materials.

Alkaline Phosphatase↗

PubMed1978

The transfer and metabolism of corticosteroids in the perfused human placenta.

The transfer and metabolism of cortisol, prednisolone, betamethasone, and dexamethasone were investigated in vitro in the perfused human placenta. Maternal and fetal circuits were established but the steroid was added to the former only. The clearance expressed as a fraction of the antipyrine transfer rate varied from 0.27 to 0.50, but there were no significant differences among the four steroids. All the steroids were metabolized extensively to their respective 11-ketosteroids and again there were no material differences among the steroids. The metabolic conversions of dexamethasone and betamethasone were far greater in the perfused placenta than in minced placenta. From the standpoint of placental transfer and metabolism, as observed in the perfusion studies, none of the four corticosteroids offers a decisive advantage in the antepartum maturation of the fetal pulmonary surfactant system.

Antipyrine↗

PubMed1978

Effect of protein binding on transfer and metabolism of cortisol in perfused human placenta.

The transfer and metabolism of cortisol and cortisone and the effect of protein binding on these processes have been investigated in vitro in the perfused human placenta. The clearance of cortisol in buffer, expressed as a fraction of the antipyrine transfer rate (clearance index), was 0.50 +/- 0.05 SEM in either direction. Extensive conversion to cortisone (85%) occurred during transfer. Addition of corticosteroid-binding globulin (CBG) in amounts sufficient to bind 50% of the cortisol reduced the clearance (0.40 +/- .026) insignificantly, whereas human serum albumin (HSA) in amounts sufficient to bind 50% of the cortisol reduced the clearance to 0.28 +/- 0.012 (P less than 0.001) even though the association constant for albumin is approximately 1000-fold less. The percent of conversion to cortisone did not change significantly with protein binding. The clearance index of cortisone from a protein-free perfusate was 0.74. With CBG and albumin in the same concentrations as used in the cortisol experiments, the binding of cortisone to CBG was 23% and its clearance was 0.70; with albumin, the binding was 45% and the clearance index was 0.45. The addition of albumin and CBG to the same perfusate resulted in a cortisol clearance equal to that obtained with perfusate containing only albumin. Binding to albumin may be more significant than binding to CBG in controlling the transfer rate of cortisol to the fetus.

Carrier Proteins↗

PubMed1977

Treatment of hypoplastic anemia in mice with placental transplants.

A genetic mutation in mice (W/Wv) causes an autosomal recessive disease characterized by hypoplastic anemia which lasts throughout life. Double-dominant W/Wv anemic mice were sublethally irradiated to facilitate repopulation of marrow with transplanted cells and were injected intravenously with suspensions of 5-10 million placental cells of 15 days gestation derived from normal, isogeneic donors. Red cell counts fell promptly after irradiation and then rose progressively over a period of weeks, reaching normal levels of the nonmutant. Mean corpuscular volume and hemoglobin electrophoresis patterns of red cells in recipient W/Wv mice resembled those of normal donor animals. The therapeutic effect lasted for the duration of the observation period, in some instances over 9 mo. W/Wv mice that were administered Hanks' solution or fetal blood, instead of placental transplants, remained anemic. Late gestation placentas (18 days) were also ineffective.

Aging↗

PubMed1976

Transfer across perfused human placenta. IV. Effect of protein binding on free fatty acids.

The effect of protein binding on the rate of placental transfer of hexanoic (C 6) and decanoic (C 10) acids was investigated in an in vitro perfusion system of human placenta. As much as 30% of transferred C 6 was converted to more polar compounds, so that the observations related to the combined effects on transfer and metabolism. Less than 10% of C 10 was similarly metabolized. Both fatty acids are soluble in buffered salt solutions at the concentrations used (40 muM) and both are bound to serum albumin, C-10 having higher association constants (K' for C 6, 1.48 X 10(4); for C 10, 1.03 X 10(5). When the placenta is perfused with buffered salt solution, the transfer of C 6 is 22% more rapid than that of C 10. It is suggested that binding within the placenta retards C 10 more than C 6. The addition of 1 g/100 ml bovine serum albumin to the maternal perfusate reduces the transfer rate of C 10 by 80%, whereas 2 g/100 ml serum albumin has a more moderate effect on C 6 (a reduction of 50%). The addition of 1 g/100 ml serum albumin to the fetal perfusate increases transfer rate of both free fatty acids (FFA), C 6 by 25% and C 10 by about 250%. With equivalent concentrations of serum albumin in maternal and fetal perfusates, the transfer rate of C 10 was reduced by 65%, whereas there was no detectable effect on transfer of C 6 in two of three experiments. The transfer rate of FFA increase logarithmically with progressive shortening of the carbon chain from C 16 to C 8 when maternal and fetal perfusates contain serum albumin. Protein binding is apparently the determining factor. The rate of transfer falls off at C 6 and C 4, 4ven though protein-binding continues to decrease. The determining factor may be the hydrophilic nature of these molecules.

Fatty Acids, Nonesterified↗

PubMed1974