Immunochemical characterization and quantification of the sex steroid-binding protein (SBP) in human amniotic fluid

The sex steroid-binding protein (SBP) is a plasma protein whose concentration in the maternal circulation increases during pregnancy. Using monospecific antibodies raised against human SBP, we could demonstrate the antigenic identity of the protein in human amniotic fluid. In this fluid, we found that the SBP concentration was correlated with the total protein concentration throughout gestation. The concentration gradient of SBP between maternal serum and amniotic fluid was compared to that of other serum proteins, in relation to their relative molecular mass, and it was concluded that SBP enters amniotic fluid in a non-specific manner similar to that of other serum proteins. It is suggested that SBP could act to sequester the sex steroid hormones in amniotic fluid.     

Tobramycin: Maternal-Fetal Pharmacology

To investigate the maternal-fetal transfer of tobramycin (TBM) and its distribution in the fetus, a single dose of 2 mg/kg was administered intramuscularly to 35 pregnant patients (13 first trimester, 22 second trimester) 0.5 to 34 h before hysterectomy. TBM concentration was assayed microbiologically in maternal serum, fetal tissues (placenta, brain, lung, liver, and kidney), and fluids (amniotic, cerebrospinal fluid [CSF], urine, and serum). Mean maternal serum half-life (1.54 h) and mean peak serum concentration of TBM were within ranges reported for nonpregnant adults. In fetal serum, half-life was 5.2 h, and TBM levels did not exceed 0.58 μg/ml. For intervals up to 34 h, the mean TBM concentration in placental tissues was 1.4 μg/g. Concentration differences related to fetal maturation were found for fetal CSF, amniotic fluid, and fetal kidney. No antimicrobial activity was found in the fetal CSF of >16 weeks' gestation. TBM was present predominantly in the second trimester amniotic fluid specimens. Fetal kidney concentrations reached 7.2 μg/g at 34 h after maternal drug administration. Higher TBM concentrations were related to advanced maturation of the fetal kidney. Second trimester fetal urine concentrations for TBM ranged from 0.1 to 3.4 μg/ml, and the fetal urinary half-life was 3.7 h. Knowledge of fetal pharmacology is essential for weighing the fetal benefits or risks of antimicrobial therapy for the infected gravid patient.     

Pharmacokinetics and pharmacodynamics of labetalol in the pregnant sheep.

The maternal-fetal disposition of labetalol, a combined alpha-1 and beta adrenergic blocker, and its pharmacodynamics in pregnancy are not well understood. This study describes the pharmacokinetics, cardiovascular and metabolic effects of labetalol in the mother and in utero fetus after a 100-mg maternal i.v. bolus administration, in the chronically instrumented pregnant sheep. Labetalol shows a triexponential decline in the mother with a total body clearance of 30.8 +/- 3.83 ml/min/kg, an apparent steady-state volume of distribution (nonparametric) of 3.02 +/- 0.18 liters/kg and terminal elimination half-life of 2.79 +/- 0.66 hr. These estimates are similar to the reported values in pregnant women. Labetalol rapidly crosses the sheep placenta. The peak fetal plasma concentration was 33.7 +/- 5.8 ng/ml, the fetal exposure to labetalol as calculated by the fetal to maternal area under the curve ratio was 14.37 +/- 1.54% and the apparent fetal elimination half-life was 3.71 +/- 0.5 hr. Labetalol persists in the amniotic and fetal tracheal fluids up to 24 hr with concentrations reaching 2- to 4 times the fetal plasma concentration. Whereas there were no significant maternal or fetal cardiovascular effects, some very significant metabolic effects were observed, including fetal and maternal lactic acidosis and hyperglycemia. Lactic acid accumulates in the fetal blood and amniotic fluid with peak concentrations (6.0 +/- 0.31 and 5.5 +/- 0.26 mM, respectively) showing a more than 300% increase over control values. The exact mechanism by which labetalol causes these metabolic effects is not clear, but it may involve its partial beta-2 agonist activity.     

Renal handling of Zn-alpha2-glycoprotein as compared with that of albumin and the retinol-binding protein.

An unusual electrophoretic pattern of the urine from a patient with malignant lymphoma was observed. One of the major proteins, identified Zn-alpha2-glycoprotein (Zn-alpha2), was isolated from the urine and partly characterized. The Stokes radius was found to be 3.24 nm and the molecular weight, determined by sodium dodecyl sulfate polyacrylamide electrophoresis, 42,000. The plasma level in healthy individuals was 39 +/- 7 (SD) mg/liter. In 12 of 25 healthy individuals, Zn-alpha2 was measurable in the urine and was found to be 1.0 +/- 1.1 mg/liter. In 23 patients with chronic glomerulonephritis (CGN), in 9 with proximal tubular dysfunction (PTD), in 23 with various renal diseases (VRD), and in 10 with malignant lymphoma, the plasma level and the urinary excretion were compared with those of albumin (mol wt 67,000) and of the retinol-binding protein (RBP, mol wt 21,000). A close correlation was found between the urine-to-plasma (U/P) ratios of Zn-alpha2 and albumin in the patients with CGN, whereas in the PTD patients the U/P ratios of Zn-alpha2 and RBP were correlated. No significant renal arteriovenous difference in Zn-alpha2 could be demonstrated. The Zn-alpha2 excretion was increased also in two patients with malignant lymphoma and proteinuria of a tubular pattern. The plasma Zn-alpha2 varied inversely with the glomerular filtration rate in the patients with renal disease, but was normal in those with malignant lymphoma. The results are consistent with the assumption of a sieving coefficient of Zn-alpha2, substantially exceeding that of albumin, but notably lower than that of smaller low-molecular-weight proteins. An increased excretion of Zn-alpha2 may be due to increased glomerular permeability as well as to defective proximal tubular reabsorption.     

Placental anticoagulant protein-I: measurement in extracellular fluids and cells of the hemostatic system

Placental anticoagulant protein-I (PAP-I), a member of the lipocortin protein family, is a potent in vitro anticoagulant whose in vivo function is unknown. Very low levels of PAP-I were present in plasma of normal volunteers (0 to 5 ng/ml) and in randomly chosen plasma specimens from hospitalized patients (0 to 28 ng/ml). Review of selected hospital records did not reveal any single clinical entity that correlated with plasma levels. PAP-I was also found in amniotic fluid (12 to 107 ng/ml) and in conditioned medium of cultured endothelial cells (49 +/- 20 ng/ml). Gel filtration experiments showed that PAP-I was intact and uncomplexed in plasma and amniotic fluid. The protein was fairly abundant intracellularly: 4080 +/- 2560 ng/mg total protein in cultured umbilical vein endothelial cells; 178 +/- 109 ng/mg in platelets; 564 +/- 384 ng/mg in leukocytes; and 8.4 +/- 4.3 ng/mg in erythrocytes. The levels of PAP-I increased in platelet-rich plasma after stimulation of platelets with arachidonic acid but not after stimulation with ADP, epinephrine, thrombin, ristocetin, or collagen. These data suggest that PAP-I probably does not function as a circulating natural anticoagulant in normal persons.     

Tetranectin in amniotic fluid, maternal serum and fetal fluids

The concentration of the newly discovered protein tetranectin has been measured in different fetal and maternal compartments. In amniotic fluid a significant, positive correlation between the tetranectin concentration and gestational age was found (a mean of 0.2 mg l-1 at week 14 to a mean of 0.5 mg l-1 at week 21). In maternal serum a slight negative correlation was found between tetranectin concentration and gestational week (a mean of 6.17 mg l-1 at week 14 to a mean of 5.79 mg l-1 at week 21). In-term cord blood collected at delivery a mean level of 6.0 mg l-1 was found, and no difference was found between arterial- and venous-blood tetranectin concentration. In fetal serum the overall mean level was 2.6 mg l-1 and a significant positive correlation between tetranectin concentration and gestational age was found. The mean level was 1.1 mg l-1 in fetal cerebrospinal fluid and no correlation to gestational age was found. Fetal tetranectin may, therefore, be correlated to fetal maturation.     

Ketoconazole kinetics in chronic peritoneal dialysis

The kinetics of oral ketoconazole in serum and peritoneal fluid were studied in six patients with renal failure receiving peritoneal dialysis. A dose of 400 mg ketoconazole resulted in a maximum blood concentration of 2.3 +/- 1.7 microgram/ml (mean +/- SD), which occurred 3.3 +/- 1.6 hours after dosing. The serum t1/2 was 2.4 +/- 0.8 hours. Peritoneal clearance values were less than 1 ml/min, and peritoneal penetration reached 3.4% of the serum concentration by 5 hours. Protein binding studies were also performed. Compared with healthy controls, patients receiving peritoneal dialysis have significantly less ketoconazole serum protein binding. Fifty to eighty percent of the drug is protein bound in the peritoneal fluid, and the unbound concentration is in the same range as that in the serum of healthy individuals with "therapeutic" total ketoconazole levels of 1 to 2 micrograms/ml.     

Polymorphism of human serum Zn-alpha2-glycoprotein and its behaviour during ontogenesis using quantitative crossed starch gel immunoelectrophoresis

Using crossed starch gel immunoelectrophoresis with rabbit anti-Zn-alpha₂-glycoprotein (Zn-alpha₂-GP) immune serum and planimetric evaluation of antigen-antibody precipitation peak area, human serum Zn-alpha₂-GP was found to consist of four major antigenically identical components (A, B, C, D), the mean concentrations of which were 8.3 ± 3.5 mg/l (A), 27.1 ± 3.0 mg/l (B), 38.7 ± 3.4 mg/l (C) and 11.1 ± 3.5 mg/l (D). The mean relative percentages of individual Zn-alpha₂-GP components were 9.7 ± 4.0% (A),31.8 ± 3.4% (B), 45.4 ± 5.2% (C) and 13.0 ± 4.0% (D). The concentrations of human serum Zn-alpha₂-GP components A, B and C increase from the lowest values in the fetal and early newborn period to the highest ones in children and adults. During ontogenesis, the mean relative percentages of the Zn-alpha₂-GP components A and B increase while those of the Zn-alpha₂-GP components C and D decrease simultaneously. The anodal mobility of the Zn-alpha₂-GP components decreases after treatment with neuraminidase. The pattern of the Zn-alpha₂-GP components in human serum was found to be very similar to that in human urine and amniotic fluid.     

Pancreatic secretory trypsin inhibitor from human amniotic fluid and fetal and neonatal urine: concentrations and physicochemical characterization

The levels and physicochemical properties of the pancreatic secretory trypsin inhibitor, also known as Kazal type trypsin inhibitor, were studied in human amniotic fluid. In the second trimester, the median concentration was 160 ng/ml, which exceeds the maternal serum levels 20-fold. Towards term, the amniotic fluid levels declined about 5-fold, whereas the maternal serum values remained constant. In fetal urine, the concentration of the trypsin inhibitor was similar to that in amniotic fluid in early gestation, whereas in newborn urine, the median level was 4-to 5-fold higher than in term amniotic fluid. The physiochemical characteristics of the trypsin inhibitor in amniotic fluid, neonatal urine and cancer urine from an ovarian cancer patient were similar, as studied by gel filtration, high performance reverse phase liquid chromatography, and complete immunological identity in immunodiffusion. The physicochemical similarity and levels in various compartments suggest fetal contribution to amniotic fluid levels of the trypsin inhibitor.     

Placental transfer of disodium sulbenicillin.

The concentrations of sulbenicillin in maternal and fetal blood and in the amniotic fluid compartment were measured in 27 women at parturition. With an intramuscular injection of 2,000 mg of sulbenicillin, the highest concentration of sulbenicillin in maternal blood (109.0 micrograms/ml) was attained at 55 min. The highest concentrations in umbilical cord blood (approximately 25 micrograms/ml) were attained between 1 and 3 h after dosage. The peak concentration in amniotic fluid (27.1 micrograms/ml) was attained approximately 7.5 h after sulbenicillin administration.     

The amnion regulates movement of fetally derived alpha-fetoprotein into maternal blood.

The present investigation documents that, under normal conditions, most fetally produced AFP reaches the maternal circulation via diffusion across the amnion from amniotic fluid. This has been determined by comparing maternal serum AFP levels with amniotic fluid albumin concentrations in paired samples. The proportionally demonstrated between them indicates a proportional, transamniotic exchange of the two proteins, each originating on opposite sides of the amnion. Albumin is known to reach amniotic fluid by transamniotic diffusion from maternal blood. All amnions restrict AFP movement into maternal serum, but some are distinctly more restrictive than others; in such cases, a relatively greater increase in amniotic fluid AFP concentration would likely have to occur from a fetal lesion before being reflected in maternal serum. Inconsistencies found in several paired samples identify that other variables may also influence passage of AFP to the mother.     

Angiotensin I-converting enzyme in amniotic fluid

Angiotensin I-converting enzyme (ACE) is present in human amniotic fluid. We characterized the enzyme by both its antigenic and enzymatic properties. Using a specific direct radioimmunoassay, ACE was quantified and characterized in each of the 19 samples tested. Mean level was 136 +/- 83 ng/ml. Amniotic ACE completely crossreacted, like that in plasma and kidney, with antibodies raised against the lung enzyme. ACE activity in amniotic fluid averaged 8.7 +/- 5.6 microU/ml using Hip-His-Leu as substrate and was significantly correlated with ACE antigen levels. ACE was not associated with the cells or the free intracellular organelles in amniotic fluid, and the enzyme was present in soluble form. Angiotensinase activity and high levels of kininase activity were found in amniotic fluid. Inhibition studies with captopril and anti-human ACE antibodies suggest that angiotensinases and kininases other than ACE were also present. Because renin, mostly in inactive form, and angiotensinogen were also found in these amniotic fluids, it appears that a complete, although not fully activated, renin angiotensin system is present in amniotic fluid and fetal membranes during pregnancy.     

Human beta-endorphin and beta-lipotropin levels in maternal and fetal plasma and amniotic fluid

We measured beta-endorphin (beta-EP) and beta-lipotropin (beta-LPH) levels in human maternal and fetal plasma and amniotic fluid, simultaneously. It appeared evident that maternal circulating levels of beta-EP (n = 11, 163.9 +/- 12.9 pg/ml, mean +/- S.E.) and beta-LPH (n = 11, 413.0 +/- 25.9 pg/ml) at delivery were significantly (p less than 0.01) higher than those of maternal plasma at term (beta-EP; n = 4, 18.3 +/- 2.1 pg/ml, beta-LPH; 213.4 +/- 24.3 pg/ml) and those of amniotic fluid (beta-EP; n = 5, 8.5 +/- 1.2 pg/ml, beta-LPH; 215.1 +/- 44.9 pg/ml). Fetal beta-EP levels (n = 11, 79.1 +/- 5.8 pg/ml) were significantly (p less than 0.01) higher than those of amniotic fluid. These data suggest that the origin of amniotic fluid beta-EP may be an increased synthesis in the maternal and fetal pituitary gland but not in the placenta.     

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).     

Extravascular penetration of highly protein-bound flucloxacillin.

The pharmacokinetics of intravenously administered flucloxacillin (2.0 g to five volunteers) are described. The passage of flucloxacillin to peripheral lymph and suction skin blisters was monitored. This drug was selected because the high serum protein binding of 96% offered a particularly good opportunity for the study of the impact on tissue penetration. Flucloxacillin was assayed by high-pressure liquid chromatography, and pharmacokinetics were assayed by computerized curve fitting to accepted models. Penetration of flucloxacillin to extravascular foci was rapid. After 30 min the drug concentrations were 0.5 +/- 0.3 microgram/ml in lymph and 0.9 +/- 0.7 microgram/ml in blister fluid. The peak concentration was 11.7 +/- 5.6 micrograms/ml in lymph and 4.6 +/- 1.4 micrograms/ml in blister fluid. Concentrations in urine were above 111 +/- 50 micrograms/ml throughout the 8-h monitoring period, and urinary recovery was 60.4%. The half-life was 2.1 +/- 0.9 h in serum, 1.4 +/- 0.6 h in lymph, and 11.0 +/- 4.1 h in blister fluid. The differences in half-life were significant (P less than 0.05) between serum and blister fluid but not between lymph and serum. Penetration, as represented by the mean ratios of areas under the curve, was 19.7 +/- 8.1% to lymph and 38.2 +/- 11.7% to blister fluid. The flucloxacillin distribution volume during the phase of elimination was 36.4 +/- 16.0 liters and the total body clearance was 12.9 +/- 5.5 liters. Flucloxacillin showed good tissue penetration, considering its very high serum protein binding. High flucloxacillin levels in lymph and blister fluid were explained in part by drug affinity to extravascular albumin. The major impacts of high protein binding are (i) slightly slower passage into extravascular sites, (ii) slightly later peak concentration, and (iii) levels in extravascular fluid that are persistently below those in serum.     

Chloramphenicol Pharmacokinetics in Hospitalized Patients

The apparent body clearance of chloramphenicol was investigated in 21 hospitalized adult patients on 27 occasions. Apparent body clearance was found to be significantly lower (1.99 +/- 1.49 ml/min per kg) in patients with total serum bilirubin concentrations of >1.5 mg/100 ml than in patients with serum bilirubin concentrations of 相似文献   

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

Abstract. 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 μ g/ml) and normal pregnant women (6.4 μ g/ml). In contrast, the diabetic group was found to have significantly ( P< 0.001) higher concentrations of amniotic fluid hPL (1.2 μ g/ml) than normal pregnant women (0.8 μ g/ml).     

Immunoassay for the determination of surfactant apoprotein (SP-A) in human amniotic fluid: comparison with other indices of assessing foetal lung maturity.

The concentration of the major surfactant-associated protein SP-A (28-36 kDa) was determined in 73 amniotic fluid samples obtained from normal (n = 40) and complicated (n = 33) pregnancies. Lecithin/sphingomyelin (L/S) ratio and phosphatidylglycerol (PG) levels were also determined in all the samples by one-dimensional step-wise thin-layer chromatography. An enzyme-linked immunosorbent assay was used to determine human lung surfactant apoprotein SP-A. The amount of SP-A in human amniotic fluid increased as a function of gestational age from 8 mg l-1 at 36 weeks to 11.75 mg l-1 at 40-41 weeks of gestation. There was a significant difference (p less than 0.01) in amniotic fluid SP-A concentration from female (9.93 +/- 0.60 micrograms ml-1) compared to male (9.10 +/- 0.52 micrograms ml-1) foetuses. In amniotic fluid samples obtained from a group of complicated pregnancies, SP-A levels were significantly lower than in the normal group when adjusted for gestational age and sex of the foetus (p less than 0.05).     

Measurement, Characterization, and Source of Somatostatin-like Immunoreactivity in Human Amniotic Fluid

Somatostatin-like immunoreactivity (SLI) is widely distributed in tissues and biological fluids. To determine whether SLI is also present in amniotic fluid, samples obtained by amniocentesis from 30 normal and 27 abnormal pregnancies were studied by radioimmunoassay. Direct incubation of [(125)I-Tyr(1)]tetradecapeptide somatostatin (SRIF) with amniotic fluid resulted in 89% tracer degradation. Damage was reduced to <5% when samples were acidified and boiled before the assay. With this technique, SLI was detectable in all normal amniotic fluid samples; the mean level at 15-20 wk of gestation (320+/-55 pg/ml, n = 15) being 4.5 times higher than the mean at 32-43 wk (70+/-12 pg/ml, n = 15) (P < 0.001). In cases of preeclampsia (n = 6), gestational diabetes (n = 5), anencephaly (n = 1), and meningomyelocele (n = 1), SLI values were in the normal range, but in one juvenile diabetic and one patient with chronic renal failure, SLI was undetectable (<10 pg/ml). In a pair of monochorionic diamniotic twins, SLI levels were very different (33 and 197 pg/ml), which suggests that fetal factors are more important than materno-placental ones in determining amniotic fluid SLI. Serial dilutions of amniotic fluid showed parallelism with standard SRIF. When concentrates of pooled amniotic fluid were chromatographed on Sephadex G-25 columns, all SLI eluted in the void volume ahead of SRIF even after treatment with 8 M urea and dithiothreitol. This "big" SLI incubated in amniotic fluid showed 100% stability over 24 h at 37 degrees C, whereas SRIF was rapidly inactivated (t((1/2)) congruent with 7 min). Extracts of placenta and fetal membranes contained no SLI, but small amounts (6-20% of total amniotic fluid SLI) were found in cells from fresh fluid. Radioimmunoassay of SLI in extracts of seven paired cord arterial and venous plasma samples showed no arteriovenous gradient consistent with fetal origin of cord blood SLI. It is concluded that (a) amniotic fluid contains SLI which is of fetal origin and (b) normal levels vary with gestational age. The SLI has a higher molecular weight (>/=5,000) and is more stable in amniotic fluid than SRIF.     

Binding of corticotropin-releasing hormone (CRH) in maternal and fetal plasma and in amniotic fluid

Placenta secretes corticotropin-releasing hormone (CRH) into the maternal and fetal circulation, but a CRH binding protein in plasma may decrease its biological activity. Using a charcoal adsorption method we found that 92% of added 125I-Tyr-CRH was bound to a binding protein in the nonpregnant plasma, 72% in the plasma at term pregnancy, 90% in umbilical cord plasma, 82% in the amniotic fluid in the second and 25% in the third trimester. CRH added to plasma inhibited the binding of 125I-Tyr-CRH over the concentration range of 0.1-8.8 nmol/l in plasma and of 0.1-2.2 nmol/l in amniotic fluid. There was a significant negative correlation (R = -0.80) between the binding capacity of the CRH-binding protein and CRH concentration in maternal plasma. Plasma or amniotic fluid was incubated with 125I-Tyr-CRH and subjected to gel filtration on Sephadex G-50. The bound radioactivity was eluted at the region of Mr 25-40 kDa and the unbound radioactivity at the location of synthetic CRH. Bound and unbound CRH concentrations were determined using charcoal adsorption method and gel filtration on Sephadex G-50 in ten maternal plasma samples at the third trimester of pregnancy. Following mean percentages were found to be bound: charcoal method 61.9 +/- 6.80% (SE) and gel filtration 62.8 +/- 6.33%. We conclude that the bulk of CRH is bound to a binding protein in maternal and fetoplacental circulation, whereas at term pregnancy the role of the binding is small in amniotic fluid.