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Biomedical subjects

I Horacek

Publications and source records attributed to I Horacek.

At least 19 recordsLinked to original sources
PubMed1989

Amniotic fluid enzymes in pregnancies with trisomy 21.

The activities of a range of microvillous enzymes in amniotic fluid from normal pregnancies (n = 213) and those complicated by trisomy 21 (n = 26) were compared in a prospective study. Using a centrifugal analyser, the activities of leucine aminopeptidase (LAP), gamma glutamyl transferase (GGT), aspartate transferase (AST), and isoenzymes of alkaline phosphate (ALP) were measured in amniotic fluid alongside alpha fetoprotein (AFP) levels. Of the markers studied, LAP was found to be the most reliable indicator of trisomy 21. Using levels below the 5th percentile, LAP showed sensitivity 73 per cent, specificity 94 per cent, and predictive value positive 63 per cent. Although these tests would not replace karyotyping in all cases, the measurement of LAP could be useful as a rapid initial screening test, particularly when amniocentesis is performed for indications other than chromosomal abnormalities.

Alkaline Phosphatase↗
PubMed1985

Malignant sequelae of molar pregnancy in Victoria.

In a retrospective study of 455 patients with confirmed molar pregnancy, registered with the Hydatidiform Mole Register of the State of Victoria in the years 1973-1982 inclusive, treatment for persistent trophoblastic activity was necessary in 62 (13.6%) patients. The need for treatment was independent of levels of urinary chorionic gonadotrophin (UCG) excretion prior to evacuation of the molar pregnancy, age, parity or blood group. All patients achieved initial remission of UCG levels within 5 courses of treatment. Risk factors were scored retrospectively and patients responded poorly if therapy inappropriate to risk factors was given. Only 2 cases of histologically proven choriocarcinoma occurred and the only death recorded was in 1 of these patients.

Adult↗
PubMed1985

Rapid enzyme analysis of amniotic fluid phospholipids containing choline: a comparison with the lecithin to sphingomyelin ratio in prenatal assessment of fetal lung maturity.

The relation between the choline containing surfactant phospholipids lecithin and sphingomyelin in amniotic fluid and fetal lung maturity is well established. An enzymatic method that had been automated and optimised for use on a centrifugal analyser was used to measure the total choline containing phospholipids in amniotic fluid. The total time taken for this assay was 10 minutes. The results obtained from 100 patient samples, using this procedure, compared favourably with the results obtained by the thin layer chromatography procedure used to determine the lecithin to sphingomyelin ratio (r = 0.93). A clinical study of 60 patients showed that this assay predicted prenatal respiratory distress syndrome as well as the lecithin to sphingomyelin ratios. The advantage of this assay over existing procedures is that it requires minimum preparation of the specimen and no extraction, is quick, and shows a high degree of precision.

Amniotic Fluid↗
PubMed1985

Automation and limitation of 17 beta oestradiol dehydrogenase in monitoring ovarian function.

An automated enzymatic assay which measures combined concentrations of urinary oestrone and oestradiol within 15 minutes of hydrolysis has been developed using placental 17 beta oestradiol dehydrogenase. This assay is comparable to radioimmunoassay in its precision and sensitivity and is quicker, more convenient, and more economical. The 17 beta oestradiol dehydrogenase assay was used to monitor ovarian response in infertile women being treated through stimulated ovarian cycles or in vitro fertilisation programmes. Because the assay did not respond to oestriol it was less reliable than total urinary oestrogens in monitoring ovarian responses, particularly during treatment with drugs which enhanced oestriol excretion. In natural ovulatory cycles rising 17 beta oestradiol dehydrogenase values preceded peak luteotropin concentrations by up to 18 hours and improved detection of ovulation. The 17 beta oestradiol dehydrogenase assay processes large numbers of urine samples quickly and economically and enables accurate monitoring of oocyte maturity and ovulation.

17-Hydroxysteroid Dehydrogenases↗
PubMed1983

Rapid acetylcholinesterase screening test for neural tube defect.

A 5-min optimized automated assay for measuring acetylcholinesterase (AChE) and total cholinesterase (ChE) in amniotic fluids is described in which a centrifugal analyzer is used. Total ChE was measured by using acetylthiocholine iodide and monitoring the color developed after 5,5'-dithiobis(2-nitrobenzoic acid) is added. We evaluated four direct and indirect procedures for measuring AChE in which thiocholine is generated. These methods involve either the specific enzyme inhibitors ethopropazine and BW284C51 or the specific substrates S-butyrylthiocholine and acetyl-beta-methylthiocholine. We found the last method distinguishes normal pregnancies most efficiently from those with neural tube defect. Filtering samples through 0.22-micron membrane filters before analysis decreased the incidence of false positives. Significantly increased AChE concentrations were noted in all abnormal pregnancies (n = 45) and in 4.8% of normal pregnancies (n = 310). The rapid AChE assay involving acetyl-beta-methylthiocholine, when applied alongside a rapid alpha-fetoprotein assay, increases the efficiency of screening programs for pregnancies with neural tube defect to 99.4%. It also identifies samples with negative results for alpha-fetoprotein that require further examination by the sensitive gel-electrophoretic test for AChE.

Acetylcholinesterase↗
PubMed1982

Evaluating fetomaternal hemorrhage by alphafetoprotein and Kleihauer following therapeutic abortions.

In a survey of 75 patients at 6-11 weeks gestation, fetomaternal hemorrhage (FMH) was detected by significant rises (greater than 2 S.D.) in maternal alphafetoprotein (AFP) levels in 57% of patients, while increased fetal cells were detected by the Kleihauer test in 24% of patients. With increasing gestation, FMH was detected more readily by both tests; however, in evaluating FMH at less than 10 weeks gestation. AFP was found to be a more sensitive and reliable marker than the Kleihauer test. We suggest that there is a gray zone for the Kleihauer test in early gestation, when erythroblasts containing embryonic hemoglobins are gradually replaced in the fetal circulation by erythrocytes containing fetal hemoglobin.

Abortion, Therapeutic↗
PubMed1981

Improved diagnosis of neural tube defects: measurement of concanavalin A-reactive variants of AFP in amniotic fluid.

The proportion of alphafetoprotein (AFP) not reacting with Concanavalin A(Con A) was determined by crossed line affinity immunoelectrophoresis (CLAIE) in amniotic fluid obtained from 16 pregnancies with open neural tube defects and other fetal abnormalities, and 25 pregnancies with normal outcome. The percentage of Con A non-reactive AFP was significantly lower in the presence of open neural tube defects (less than 3.9%, n = 13) compared with that in normal pregnancy (range 6.4-25.2%, n = 25). In this retrospective analysis, 2 pregnancies affected by open neural tube defect escaped diagnosis on the basis of an ambiguous total AFP estimation (+2SD less than x less than +5SD) in the amniotic fluid. These observations suggest that the elimination of false diagnose based on total AFP levels may be possible, if supplementary analysis by CLAIE is performed.

Amniotic Fluid↗
PubMed1981

Two-hour assay for lutropin during ovulation.

A rapid lutropin assay with a 2-h incubation time and a second antibody/polyethylene glycol separation step is presented. Assay time is shortened by incubating at 37 degrees C and using relatively high concentrations of antibody and radioligand. The interval required for the antigen/antibody reaction varies directly with lutropin concentration, from 1 h for ovulation values to 8 h for low values. After a 2-h incubation, low concentrations have reached 80% of their equilibrium concentration. Separation of the bound fraction by use of combined second antibody/polyethylene glycol (50 g/L) gave one-third the nonspecific binding and as rapid a separation as with polyethylene glycol (180 g/L) alone. Optimal conditions for separating the immune complex were established, and separation was found to be independent of protein concentrations in urine or serum. This tested assay can detect increasing and ovulatory lutropin concentrations in urine or serum, but with some sacrifice in sensitivity.

Female↗
PubMed1979

The relation between maternal serum alpha-fetoprotein levels and fetomaternal haemorrhage.

Spontaneous fetomaternal haemorrhage at 14 to 20 weeks gestation resulted in raised serum alpha-fetoprotein (AFP) levels in 13 of 150 patients attending a genetic counselling clinic. In all 13 patients, the placenta was anterior or fundal in position. By allowing for a rise in serum AFP levels of 4 microgram/l for each fetal cell seen in 30 high power fields (Kleihauer test), a 62.5 per cent reduction in the number of patients selected for amniocentesis because of raised serum AFP levels would have been achieved. The occurrence of fetomaternal haemorrhages at the time of amniocentesis can be detected by either the Kleihauer technique or the measurement of maternal serum AFP levels.

Adult↗
PubMed1979

Amniotic fluid palmitic acid/stearic acid ratios. Lecithin/sphingomyelin ratios and palmitic acid concentrations in the assessment of fetal lung maturity in diabetic pregnancies.

The lecithin/sphingomyelin (L/S) ratio, palmitic acid concentration and palmitic to stearic acid (P/S) ratio were estimated on samples of amniotic fluid obtained from 66 patients with diabetes. These were compared with similar estimates on amniotic fluid obtained from 127 non-diabetic patients. At 35 to 40 weeks, significant differences were observed between the L/S ratio and palmitic acid concentration in diabetics and non-diabetics, whereas the P/S ratio was similar in the two groups. The amniotic fluid L/S ratio, palmitic acid concentration, and P/S ratio were estimated on amniotic fluid obtained from 20 diabetic patients within 48 hours of induction, and the clinical outcome of the newborn infant was used to assess the predictive value of the three parameters. In 19 out of 20 diabetics the P/S ratio correctly predicted fetal lung maturity, whereas the palmitic acid concentration was correct in 12 patients and the L/S ratio in only 10 patients.

Amniotic Fluid↗
PubMed1979

Amniotic fluid beta 2 microglobulin: correlation with L/S ratios and creatinine levels.

Beta 2 microglobulin (beta 2 m) levels were measured in amniotic fluids taken after the 32nd week of gestation. Beta 2 m levels fell continuously from 5.2 microgram/ml at the 32nd week to 3.08 microgram/ml after the 39th week of gestation. Abnormally high levels of beta 2 m were found in 12.6% of samples. There was a significant correlation between beta 2 m levels and lecithin/sphingomyelin ratios at 32 weeks of gestation and with creatinine levels at 37-38 weeks (P less than .05). Although elevated beta 2 m levels may be associated with maternal and/or fetal abnormalities, the precise relationship is not clearly established: in particular, our data do not suggest that estimation of beta 2 m levels could be of value in determining fetal maturity.

Amniotic Fluid↗
PubMed1979

Potassium: aldosterone relationships in pregnant ewes and chronically cannulated ovine fetuses.

UNLABELLED: As maternal hyperkalemia quickly induces fetal hyperkalemia, it was decided to investigate the effect of small elevations of plasma [K+] on the peripheral blood aldosterone concentration in chronically catheterized ovine fetuses and to compare this response to that obtained in the adult ewe both pregnant and nonpregnant. Fol elevations of plasma [K+] of 0.1 to 0.3 mmole/liter blood aldosterone concentrations were elevated by 6.7 +/- 4.9 (9) ng/dl in nonpregnant sheep, 6.3 +/- 5.0 (6) in pregnant ewes, but only 0.3 +/- 1.7 (4) in fetal sheep. For increments in plasma [K+] of 0.4--1.0 mmole/liter aldosterone increments in nonpregnant ewes were 9.5 +/- 4.5 (4) ng/dl compared with 10.1 +/- 4.7 (5) in pregnant ewes and 1.5 +/- 2.6 (7) in fetuses. There was no obvious correlation between the age of the fetus and the response to increased plasma [K+]. In effect, the blood aldosterone concentration of the fetus was not elevated by increasing plasma plasma [K+]. SPECULATION: The ovine fetus is not able to cope with hyperkalemia by increasing blood aldosterone concentration. Until the fetus is close to term, hyperkalemia may jeopardize the pregnancy by causing placental hemorrhages.

Aldosterone↗
PubMed1978

The effects of antidiuretic hormone on urine flow and composition in the chronically-cannulated ovine fetus.

The fetuses of nine pregnant ewes were chronically cannulated between 86 and 130 days with cannulae in one carotid artery, one jugular vein, the fetal bladder and the amniotic cavity. The effects of infused AVP on fetal urine flow rate and composition were studied. A dose of 35 pmol. h-1 always caused an increase in urine osmolality and a decrease in flow rate and free water clearance without change in blood pressure. Higher doses (140 pmol.h-1) were significantly pressor and caused increased excretion of sodium, chloride, urea and creatinine. Although this dose always caused an increase in urine osmolality, in five experiments the flow rate also rose. It is concluded that the ovine fetus has the ability to control its own urine flow and composition, and possibly also amniotic fluid volume and composition.

Animals↗
PubMed1978

Factors influencing jaundice in immigrant Greek infants.

A study of 887 consecutively born immigrant Greek and 220 Anglo-Saxon Australian infants has shown that serum bilirubin concentrations are influenced by these factors: breast feeding, delivery with forceps, gestation, birthweight, sex of the infant, presence of hypoxia, presence of blood group incompatibility, a positive direct Coombs's test, maternal sepis, and administration to the mother of promethazine hydrochloride, reserpine, chloral hydrate, barbiturates, narcotic agents, diazepam, oxytocin, aspirin, and phenytoin sodium. Apart from the administration of promethazine hydrochloride, reserpine, chloral hydrate, and quinalbarbitone sodium, only two factors, breast feeding and delivery by forceps, occured with different frequencies in the immigrant Greek and the Australian infants. Among the Greek infants with jaundice, there were few where the cause of the jaundice was inapparent. The immigrant Greek and Australian newborn populations were therefore remarkably similar. Since differences of frequency and severity of jaundice do exist in infants born in Greece, this difference must be lost when the parents emigrate, and therefore an environmental factor must be incriminated as the causative agent for jaundice of unknown origin in Greece.

Australia↗
PubMed1978

Regulation of amniotic fluid volume and composition in the ovine fetus.

To determine the role of fetal swallowing in the control of amniotic fluid volume and composition and fetomaternal sodium transport, 4 ovine fetuses of 101--129 days' gestation had their esophagi surgically occluded. Amniotic and fetal vascular cannulas were implanted at the same time in these fetuses and in four intact controls. There was no difference between the amniotic sodium or potassium of these two groups over the next 3 weeks, at which time cesarean section was performed and the volume of amniotic fluid measured. Hydramnios did not result from esophageal atresia. Twenty-four hours after injection of 24Na into the amniotic fluid, the percentages of the dose in the fetal/maternal compartment were similar in intact and esophagus-ligated fetuses.

Amniotic Fluid↗
PubMed1977

Amniotic fluid lecithin/sphingomyelin ratio in pregnancy complicated by diabetes.

The lecithin/sphingomyelin (L/S) ratio in the amniotic fluid of 57 patients attending an antenatal diabetic clinic was determined. The L/S ratio in Class A, B and C patients (White, 1965) showed a similar rise with gestation to nondiabetic patients; 89 per cent in this group had an L/S ratio above 2 : 1, but of these 27 per cent developed mild or moderate respiratory distress syndrome (RDS). In Class D, F and R diabetic patients there was a little correlation of the L/S ratio with gestational age and in this group 55 per cent of the infants developed some form of RDS. The value of measuring amniotic fluid L/S ratios in the diabetic pregnancy is questioned.

Amniotic Fluid↗