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Biomedical subjects

D M Saunders

Publications and source records attributed to D M Saunders.

At least 55 records · Page 3Linked to original sources
PubMed1991

Radioimmunoassay of inhibin based on synthetic human inhibin alpha-chain peptide.

Polyclonal rabbit antisera were produced against cyclic human inhibin [(Cys6, Tyr7) alpha-(6-30)NH2] peptide, covalently conjugated to bovine serum albumin. The tyrosine residue introduced at position 7 facilitated the oxidative incorporation of radiolabel (125I) to yield a tracer with specific activity of 73.9 Ci/g. These reagents were used to develop a homologous equilibrium radioimmunoassay for human inhibin, with polyethylene glycol, 200 g/L, serving as the separation phase. At a detection limit of 2 micrograms/L (n = 7), immunoactive inhibin was detectable in human pre-ovulatory follicular fluid (128 micrograms/L), seminal plasma (2374 micrograms/L), amniotic fluid (66 micrograms/L), and placental extract (347 micrograms/L). We also demonstrated inhibin immunoreactivity in biological fluids from other mammalian species: macaque, chimpanzee, porcine, and bovine, but not rodent (guinea pig). Although the antisera were raised against a nonbioactive inhibin peptide, immunoglobulins fractionated on Protein A-Sepharose neutralized the bioactivity of human ovarian inhibin. Further characterization of inhibin immuno- and bioactivity was undertaken with immobilized heparin, divalent metal cations, and dye ligands. Only heparin-Sepharose distinguished between immuno- and bioactive inhibin.

Amniotic Fluid↗
PubMed1990

A baboon model for pregnancy-associated antigens (PAPP-A, PP5, PP14).

By radioimmunoassays established on human derived antigens, PAPP-A, PP5 and PP14 immunoreactivity was detected in placental extracts and blood of pregnant baboons. None of the serial dilution curves suggested parallelism between respective human and baboon samples. Based on slopes of regressed logit-log transformed binding data, PAPP-A demonstrated the greatest degree of interspecies immunological crossreactivity. PP14 showed the least conservation of antigenic determinants. Physicochemical characterization on heparin, zinc chelate and bovine thrombin affinity matrices could not distinguish human from baboon-derived antigens. As in the human, baboon PAPP-A and PP5 were not detected in blood of male or non-pregnant animals. PP14 was detected in baboon follicular fluid, and only PP5 immunoreactivity was measured in culture media of baboon embryos. Of the three antigens, PAPP-A was detected in pregnant baboons at about 61 days gestation, that is, 4 weeks before PP5 and PP14. With the exception of PP14 which attained peak concentration at 118 days of pregnancy, PAPP-A and PP5 concentrations were greatest at term. In conjunction with physicochemical and immunological criteria, these physiological kinetics clearly support a role for developing a baboon model to serve for further studies into feto-maternal signals, particularly antigens such as PAPP-A and PP5.

Animals↗
PubMed1990

Elevated luteal phase estradiol:progesterone ratio in mice causes implantation failure by creating a uterine environment that suppresses embryonic metabolism.

Failure of implantation after in vitro fertilization is sometimes associated with elevated estradiol (E2):progesterone (P) ratios in the early luteal phase. Using the mouse to study the causes of the contragestational actions of elevated E2:P ratios, it was confirmed that administration of E2 (40 to 80 ng) before implantation inhibited implantation and 0.4 mg of P totally reversed the effect of 40 ng E2. Fluids collected from the uterine lumen of E2-treated (40 ng) mice significantly inhibited the incorporation of 3H-uridine by mouse blastocysts in vitro, whereas fluids from mice treated with E2 (40 ng) and P (0.4 mg) together had no inhibitory effect. In contrast to these contraceptive effects of high E2, lower levels of E2 (5 and 20 ng) caused an increase and no change to the implantation rate, respectively, and fluids from mice treated with E2 (20 ng) significantly enhanced blastocyst metabolism. Concomitant administration of P to these low dose E2 mice enhanced these effects. Thus, a large elevation of the E2:P ratio inhibited implantation and created a uterine lumenal milieu that suppressed embryonic metabolism. These effects could be reversed and implantation re-established by the correction of the E2:P ratio by exogenous P.

Animals↗
PubMed1990

Measurement of human embryo-derived platelet-activating factor (PAF) using a quantitative bioassay of platelet aggregation.

A quantitative bioassay was used to measure the concentration of platelet activating factor (PAF) in medium in which human embryos produced by IVF had been cultured and in various other biological fluids. Following extraction and partial purification, 121 of 228 (53%) media samples in which single human embryos were cultured for 24 h had PAF levels greater than found in corresponding control media. This was assigned as embryo-derived PAF and the corresponding embryos termed 'PAF-positive'. Medium from those PAF-positive embryos transferred to patients who achieved an ongoing pregnancy had a mean PAF concentration of 295 +/- 107 nM (mean +/- SEM, n = 55), which was significantly greater (P less than 0.03) than media of PAF-positive embryos transferred to patients who failed to become pregnant (75 +/- 27 nM, n = 66, t-test). The embryos with the faster cleavage rates tended to secrete more PAF (P less than 0.01). Although a greater proportion of culture media derived from embryos transferred to patients who achieved a pregnancy were PAF-positive (66 out of 121, 54.5%) compared with those transferred to patients who failed to achieve a pregnancy (55 out of 121, 45.4%), this was not significant (P greater than 0.05). It was observed that 13% of women who achieved a pregnancy had embryos transferred which did not produce significant amounts of PAF in vitro. This occurred in 26% of women not achieving pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Assay↗
PubMed1990

A protein marker of hamster oocyte fertilization.

Using a polyclonal rabbit antiserum directed against guinea-pig heparin-binding placental protein (HBPP), we have demonstrated by indirect immunofluorescence the expression of this antigen by hamster preimplantation embryos. HBPP was localized to blastomeres, but not to the zona pellucida, of hamster preimplantation embryos conceived in vivo. Hamster embryos, from the pronuclear to hatched blastocyst stages, were HBPP-positive with greatest immunofluorescence detected at the pronuclear to 2-cell stages. Thereafter, HBPP-dependent fluorescence diminished. By contrast, mature spermatozoa and unfertilized metaphase II oocytes were HBPP negative. Direct microinjection of spermatozoa or diluent through the zona pellucida and into the ooplasm activated the oocytes to express HBPP. These findings demonstrate that expression of HBPP is a post-conceptional event limited to fertilized (or activated) oocytes and that transcription of paternal genomes was not required for HBPP expression. The distribution and temporal kinetics suggest that HBPP may be secreted or released by activated cortical granules into the perivitelline space and concentrated at the oolemma. Whereas hamster embryos conceived in vivo consistently demonstrated a uniformly distributed immunofluorescence, non-viable and degenerate embryos showed weak and patchy reactions. Thus, we have identified a heparin-interacting protein which may serve as a marker of in-vivo and in-vitro oocyte activation and embryo quality.

Animals↗
PubMed1989

Supplementation of in-vitro fertilisation culture medium with platelet activating factor.

The supplementation of culture medium with platelet activating factor (PAF) on the subsequent implantation and pregnancy potential of pre-embryos produced by in-vitro fertilisation was studied. Pre-embryo culture medium was supplemented with 0 (control), 0.186, 0.93, or 1.49 mumol/1 PAF. Pre-embryos were transferred to PAF-containing medium 15-17 h after insemination (ie, just before syngamy) for 24 h and then transferred to the uterus. For 185 women receiving control pre-embryos, the pregnancy rate (positive beta human chorionic gonadotropin per oocyte retrieval) was 10.2%, while 166 women who received PAF treated pre-embryos (all concentrations combined) achieved a pregnancy rate of 17.5%. This difference was significant. The pregnancy rates per pre-embryo transferred were 6.1% and 9.4% for the control and PAF groups, respectively. The percentage of positive pregnancy tests that resulted in a viable pregnancy (presence of fetal heart at 8 weeks) was 78.9% in the controls and 75.9% in the PAF group. There was no difference in the average number of embryos transferred in either group. The increase in the pregnancy rate after a short exposure of pre-embryos to PAF in vitro suggests that PAF mediates pre-embryo development.

Chorionic Gonadotropin↗
PubMed1989

The wider perinatal significance of the Australian in vitro fertilization data collection program.

The most recent report (1986) from the Australian Register of In Vitro Fertilization pregnancies comprises 2242 in vitro fertilization (IVF) pregnancies and 261 gamete intrafallopian transfer (GIFT) pregnancies. A review of this data base indicated that this population had a relatively high incidence of both obstetric and perinatal morbidity and perinatal mortality. About 58% of the IVF pregnancies resulted in live births and 36.4% of the infants weighted less than 2500 gm at birth. These high rates could be partially accounted for by maternal prepregnancy risk factors, such as age, and by risk factors associated with the infertility management, such as multiple pregnancy (22% of all pregnancies more than 20 weeks), which accounted for approximately 50% of the preterm births (less than 37 weeks). Singleton pregnancies also had a higher incidence of preterm birth (17.8% at gestational age 24 to 36 weeks), low-birthweight babies (15.9% less than 2500 g) and perinatal mortality rates (35.4% per 1000 live births) than the Australian population at large. This warrants these patients being regarded as high risk. It is reassuring that the incidence of major malformations in IVF births (2.2%) is similar to that in the general population (1.4%).

Australia↗
PubMed1988

Biochemical and pharmacological characterization of human embryo-derived platelet activating factor.

The soluble platelet activating factor (PAF) produced by mouse embryos was shown to have properties similar to 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphocholine (PAF-acether). In this study PAF was extracted from the medium in which human embryos were cultured for approximately 18 h prior to transfer. The extracted embryo-derived PAF moved on silica thin layer chromatograms with the same RF of 0.26 +/- 0.03 (n = 26) as PAF-acether. Embryo-derived PAF or PAF-acether activity was assayed by monitoring the decrease in the proportion of single platelets in rabbit whole blood due to aggregation on incubation at 37 degrees C. The two agonists were said to be of the same activity, if they induced the same degree of platelet aggregation after 15 min incubation. PAF-acether (93 nM) and embryo-derived PAF of similar activity induced an identical time response of platelet aggregation, the response being maximal by 6 min. PAF-acether, over the range 5.6-200 nM, induced a decrease that was linear when plotted on a log-log scale. Embryo-derived PAF and PAF-acether (184 nM) gave identical dose responses when serially diluted to 16 nM. Pharmacologically, the action of embryo-derived PAF and PAF-acether (46 nM) on platelet aggregation was significantly inhibited by 3.75 microM of the PAF-specific receptor inhibitor, SRI 63-441, and completely inhibited at 15 microM SRI 63-441. Embryo-derived PAF and PAF-acether (184 nM) were inactivated to the same degree by incubation with 5-13 IU/ml phospholipase A2 (pA2).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Transvaginal pulsed Doppler ultrasound assessment of blood flow to the corpus luteum in IVF patients following embryo transfer.

The waveforms of vessels supplying the ovaries of women on an in-vitro fertilization (IVF) programme were studied using transvaginal B-mode and Doppler ultrasound. There were 125 scans recorded in 65 women at weekly intervals from 3 days after embryo transfer or 5 days after gamete intrafallopian transfer (GIFT) until confirmation of pregnancy or onset of menses. At each examination the signals obtained from vessels supplying the ovaries were recorded and quantified using a resistance index (RI). Fifteen patients became pregnant of whom one has subsequently miscarried. There was a highly significant difference in the RI values between patients who became pregnant and those who did not; no patient who became pregnant had a RI greater than 0.5. Oestrogen to progesterone ratios were calculated in the subgroup of non-pregnant patients and there was no correlation between these values and the RI values. This new technique enables prediction of IVF treatment failure earlier than has been reported previously and may reflect the inadequacy of the corpus luteum.

Corpus Luteum↗
PubMed1988

The development of action lines in an Australian maternal serum alphafetoprotein screening service for neural tube defects.

A retrospective study covering the period from January 1, 1980 up to June 30, 1982 was conducted, producing the first definitive normal range for maternal serum alphafetoprotein from the Royal North Shore Hospital in Sydney. The normal range established is based on and applicable to the pregnant women tested at this NSW laboratory. Maternal serum alphafetoprotein levels had been determined by radioimmunoassay for 3,182 pregnancies between 13 and 20 weeks' gestation. Five anencephalics and 2 open spina bifidas were noted in the study. Only one of these abnormalities (spina bifida) was associated with maternal serum alphafetoprotein levels within the normal range, the remainder all having elevated levels. Low false positive and false negative rates of 1.16% and 0.03% respectively were obtained in this study.

Female↗
PubMed1988

The impact of an instant pregnancy test kit on the operations of a major hospital casualty department.

The records of all patients on whom a casualty department pregnancy test was performed during the first 4 months of 1986 were retrospectively examined and compared with the records of all patients who in the first 4 months of 1987 had had an instant pregnancy test performed in the same casualty department, to determine the impact of such a kit on diagnostic accuracy, operative procedures and related economic factors. It was demonstrated that instant pregnancy testing significantly improved the accuracy of provisional diagnoses and appeared to help in reducing the number of surgical procedures performed. Furthermore, it was shown that a combination of careful clinical assessment plus the appropriate application of an instant pregnancy test kit could result in a cost saving to the hospital of over $41,000 per annum.

Cost-Benefit Analysis↗
PubMed1988

Vasa praevia: another cause for concern in in vitro fertilization pregnancies.

A case is reported of the velamentous insertion of the umbilical cord into the membranes of the placenta, unsuspected until delivery, in an in vitro fertilization pregnancy. Abnormal placental development adds a new dimension of risk to these pregnancies. The Australian Register of in vitro fertilization (IVF) pregnancies has shown (1) an increase in perinatal mortality rates but there are many possible causes for such an increase. A recent report (2) has suggested a higher incidence of velamentous and marginal insertions of the umbilical cord in IVF pregnancies. We wish to report a case of marked velamentous insertion of the cord which was associated with an uncomplicated vaginal delivery, but highlights the possible increased risks of vasa praevia in IVF pregnancies.

Female↗