Iioka H

Characterization of Human Placental Activity for Transport of L-alanine, Using Brush Border (Microvillous) Membrane Vesicles

The uptake of taurocholate into brush border membrane vesicles prepared from human full term placenta was studied using a rapid filtration technique. The taurocholate uptake into brush border membrane vesicles was sensitive to extravesicular osmolarity, and pre-incubation of the brush border membrane vesicles with the taurocholate increased the uptake of taurocholate into the brush border membrane vesicles. These findings indicate that the uptake of taurocholate by brush border membrane vesicles represents transport into vesicles. The uptake of taurocholate into vesicles was not dependent on Na+ electrochemical gradient (extravesicular > intravesicular). But this uptake was markedly increased when the intravesicular space was rendered electrically more positive by the use of lowly permeant anions or valinomycin-induced K+ diffusion membrane potentials. These findings indicate that the taurocholate transport into brush border membrane vesicles was dependent on membrane potential. The initial rate of taurocholate transport into brush border membrane vesicles exhibited saturation kinetics with respect to the taurocholate concentration, an apparent Km of 67 microM and Vmax of 0.30 nmol/mg protein/20 sec were calculated.

Changes in Blood Level of Lipid Peroxide and Vitamin E during Pregnancy: Clinical Significance and Relation to the Pathogenesis of EPH Gestosis

The present study was undertaken in order to determine the changes in blood levels of lipid peroxide and vitamin E in EPH gestosis. The mean plasma level of lipid peroxide was 0.89 +/- 0.13 nmol/ml for nonpregnant women, while for normal pregnant women it was 2.51 +/- 0.52 nmol/ml, and 4.10 +/- 0.72 nmol/ml for women with EPH gestosis. The mean plasma level of vitamin E was 6.7 +/- 1.0 micrograms/ml for nonpregnant women, while for normal pregnant women it was 14.5 +/- 2.2 micrograms/ml and 12.6 +/- 1.2 micrograms/ml for women with gestosis. The mean red cell level of vitamin E was 3.55 +/- 0.25 micrograms/ml packed red cells in nonpregnant women, while in normal pregnant women it was 2.56 +/- 0.34 micrograms/ml packed cells and 2.90 +/- 0.28 micrograms/ml packed cells for women with EPH gestosis. The mean platelet level of vitamin E was 99 +/- 25 micrograms/g protein for nonpregnant women, while in normal pregnant women it was 232 +/- 24 micrograms/ml protein and 205 +/- 32 micrograms/g protein for women with EPH gestosis. It was shown in this study that in EPH gestosis the plasma level of lipid peroxide increased while the levels of vitamin E which inhibited the formation of lipid peroxide decreased in plasma, red cells and platelets.

Clinical Use of Human Hepatocyte Growth Factor in the Early Detection of HELLP Syndrome

The change in plasma concentration of human hepatocyte growth factor (hHGF) in pregnant women with HELLP (hemolysis, elevated liver enzyme and low platelets) syndrome was investigated, and the following results were obtained. (1) The plasma concentration of hHGF in pregnant women did not change with the gestational stage. (2) The plasma concentration of hHGF in pregnant women with EPH (edema, proteinuria and hypertension) gestosis was 0.19 +/- 0.07 ng/ml and did not differ greatly from that in control pregnant women. (3) The plasma concentration of hHGF in pregnant women with HELLP syndrome was 1.79 +/- 0.35 ng/ml; it was increased prominently compared to control pregnant women. (4) The plasma concentration of hHGF in pregnant women with HELLP syndrome changed parallel to the clinical symptoms of the syndrome.

Platelet aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles.

We investigated the platelet aggregation inhibiting activity of human placental brush border membrane vesicles (BBMV) and obtained the following results. A strong platelet aggregation inhibiting activity existed in placental BBMV. The BBMV inhibited the platelet aggregation induced by ADP, arachidonic acid, collagen and ristocetin in a dose-dependent manner. The protein concentration of BBMV giving 50 per cent inhibition was 52 +/- 6 micrograms/ml for ADP-induced platelet aggregation, 21 +/- 2 micrograms/ml for arachidonic acid-induced platelet aggregation, 19 +/- 2 micrograms/ml for collagen-induced platelet aggregation and 107 +/- 9 micrograms/ml for ristocetin-induced platelet aggregation. There was a high level of ADP degrading activity (ADPase activity) in the placental BBMV. ADP degrading activity of the BBMV: 10.5 +/- 0.5 mumol/mg protein/min was 21 times greater than that of homogenate of the placental villi. The placental BBMV inhibited platelet TXA2 production. In the 40 micrograms/ml protein concentration of placental BBMV, platelet TXA2 production was almost completely inhibited.

Platelet aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles: the role of alkaline phosphatase

Human placental chorioepithelial brush border membrane, which is in direct contact with maternal blood flow, has platelet aggregation inhibiting activity. In the present study, the mechanism of this action has been examined in relation to ADP (adenosine diphosphate) degrading activity and alkaline phosphatase activity of brush border membrane vesicles (BBMV). BBMV prepared from human early and term placental villi, inhibited platelet aggregation induced by ADP. BBMV had potent ADP degrading (ADPase) activity. ADP was quickly degraded by BBMV. ADP degrading activity of BBMV was not so different between early and term placenta. Alkaline phosphatase activity of late placental BBMV was about three times greater than that of early placental BBMV. On the other hand, ADP degrading activity of late placental BBMV was almost the same as that of early placental BBMV. Inhibiting activity of platelet aggregation induced by ADP and ADP degrading activity of BBMV, were not inhibited by levamisole (alkaline phosphatase inhibitor).

Studies on placental inhibition of platelet aggregation: A comparison of human syncytiotrophoblast brush border and basal plasma membranes

We compared the platelet aggregation inhibiting activity of human placental syncytiotrophoblast brush border membrane vesicles (BBMV) and basal plasma membrane vesicles (BpMV), and obtained the following results. Strong platelet aggregation inhibiting activity is found in placental BBMV. BBMV inhibited platelet aggregation induced by ADP (adenosine diphosphate) and arachidonic acid in a way which depended on the protein concentration of BBMV added. In contrast, BpMV showed no detectable platelet aggregation inhibiting activity. Quite high ADP degrading activity (ADPase activity) was present in the placental BBMV. ADP was quickly degraded by BBMV. In contrast, BpMV did not degrade ADP so quickly. Platelet TXB2 production was almost completely abolished at the protein concentration of 40 micrograms/ml of BBMV. In contrast, BpMV did not significantly inhibit platelet TXA2 (TXB2) production. These results show that syncytiotrophoblast brush border and basal plasma membranes of the human placenta have markedly different properties with respect to platelet aggregation inhibiting activity.

Platelet-aggregation inhibiting activity of human placental chorioepithelial brush border membrane vesicles and basal plasma membrane vesicles

Summary This laboratory investigated the platelet-aggregation inhibiting activity of human placental brush border membrane vesicles (BBMV) and basal plasma membrane vesicles (BpMV), and obtained the following results. o 1) A strong platelet-aggregation inhibiting activity exists in placental BBMW. In a 20 μg/ml protein concentration, the BBMV completely inhibited the secondary platelet aggregation induced by ADP. In a 40 μg/ml protein concentration, the BBMV completely inhibited the platelet aggregation induced by arachidonic acid and collagen, and in a 200 μg/ml protein concentration, the BBMV completely inhibited the platelet aggregation induced by ristocetin. However, placental BpMV did not show prominent platelet-aggregation inhibiting activity on platelet aggregation induced by ADP, arachidonic acid, collagen, or ristocetin. 2) A strong ADP degrading activity (ADPase activity) in the placental BBMV was found. ADP-degrading activity of the BBMV was 10.5±0.5 μmol/mg protein/minute and ADP-degrading activity of BpMV was 0.6±0.1 μmol/mg protein/minute. 3) The placental BBMV inhibited platelet thromboxane A 2 (TXA 2 ) production. In a 40 μg/ml protein concentration of placental BBMV, a platelet TXA 2 (TXB 2 ) production was almost completely inhibited. BpMV did not show prominent inhibitory activity on platelet TXA 2 (TXB 2 ) production. These results indicate that brush border membrane and basal plasma membrane have a different function in the respect of platelet-aggregation inhibiting activity, and that the brush border membrane may play an important role inhibiting platelet aggregation.

Platelet Aggregation Inhibition Activity of Placental Brush Border Membrane

Thrombus occurs frequently in the placental chorionic lumen of patients with Pre-ecclampsia (EPH) gestosis, and participation of platelets is suggested in the pathology of the diseases. In the placental tissues, there is an antiplatelet aggregating factor which plays an important role in the maintenance of microcirculation in the placenta. The brush border membrane of the placental chorioepithe-lium plays the part of the vasoendothelium as it is the point of direct contact with the maternal blood flow in the chorionic lumen. It has already been confirmed that a strong inhibitory action on platelet aggregation is present in the vasoendothelium, and its main active mechanism is shown to be prostacyclin (PG I2) and ADP degrading by an ADPase-like activity which exists in edothelial membrane. Thus, it is quite possible that some inhibitory activity on platelet aggregation exists in the brush border membrane of placental chorioepithelium. We, therefore, investigated the presence of such an inhibitory activity on platelet aggregation as well as its properties using a fraction of the brush border membrane.

EVALUATION OF EXTRA-UTERINE ADAPTATION OF PREMATURE NEONATES AND IUGR INFANTS BASED ON HbF SWITCHING

The switching of HbF to HbA was observed in 40-week AFD infants. Four weeks post partum HbF was 65%, decreasing to 50% at eight weeks. Premature neonates, however, took 3 weeks longer to reach a similar level. This phenomenon in premature neonates is thought to be related to their immaturity. To determine whether the HbF switching ratio of IUGR infants is also lower m than that of normal infants, C-leucine was adminstered to HbF in red blood cells in umbilical blood to judge by the synthesis ratio. The synthesis ratio in 28-week premature neonates was 91%, significantly higher than the 65% ratio of term infants. In IUGR infants as well, the ratio of 73% indicated an obvious delay in HbF switching compared with term AFD infants. Moreover, the concentration of 2,3DPG in IUGR infants was often low at birth, also indicating a delay in extra-uterine adaptation. With IUGR neonates it was found that HbF switching to HbA was delayed and in most cases there was a low concentration of 2,3DPG, which enhances oxygen supply to the tissues. These two factors indicate that IUGR infants have a lower capacity for extrauterine adaptation than normal infants.

Nephritogenic Glycoprotein VIII Isolation and Partial Characterization of Nephritogenic Glycopeptide (Nephritogenoside) from the Terminal Chorionic Villus of Human Placenta

A glycopeptide comparable to human renal nephritogenic glycopeptide (nephritogenoside) of glomerular basement membrane (GBM) origin was isolated and purified from human placenta. Trophoblast basement membranes (TrBM) were isolated from placental terminal villi by ultrasonic disruption, and digested with trypsin and then with pronase. TrBM were then fractionated by zone electrophoresis, concanavalin A (Con A) affinity column chromatography and Bio-Gel P200 column chromatography. From 250 g (wet weight) of human placental terminal villi, we obtained a purified sample of 0.7 mg (dry weight) of glycopeptide. Ouchterlony gel diffusion demonstrated the existence of a common precipitin line between purified human placental glycopeptide and antiserum against human renal nephritogenic glycopeptide prepared from GBM. The sugar composition of this glycopeptide was rich in glucose (glucose, galactose and mannose were in the ratio of 1.00:0.30:0.33) and the amino acid composition of this glycopeptide contained no collagenous components. These results indicate that at least one of the nephritogenic substances common to the placenta and kidney is a glycoprotein rich in glucose and different from the collagenous component of the basement membrane.