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T Chard

Publications and source records attributed to T Chard.

At least 307 records · Page 17Linked to original sources
PubMed1981

Characterization of placental luteinizing hormone-releasing factor-like material.

High pressure liquid chromatography (HPLC) and radioimmunoassay were employed to characterize luteinizing hormone-releasing factor (LRF)-like material in the human placenta. Methanol extracts of the placenta were washed with acetic acid and chloroform, further purified on coarse octadecylsilane columns, fractionated on HPLC, and tested by radioimmunoassay. In HPLC, placental LRF had the same retention time as synthetic LRF, and such fractions gave an inhibition curve which was parallel to that of synthetic LRF in radioimmunoassay. It is concluded that human placental LRF is similar or identical to LRF in the central nervous system.

Chromatography, High Pressure Liquid↗
PubMed1981

Pregnancy specific beta 1 glycoprotein and chorionic gonadotrophin in early human pregnancy.

Venous blood samples were collected prospectively in ten menstrual cycles where conception occurred, and for several weeks thereafter, and the circulating concentrations of pregnancy specific beta 1 glycoprotein (SP1) and human chorionic gonadotrophin (HCG) determined using specific radioimmunoassays. The data were converted to logarithms and pooled and pooled using the day of the LH peak as zero time. The concentration profiles so obtained were remarkable similar and showed a rapid exponential increase in concentration during the very early stage of pregnancy. The doubling times were 2.4 days and 2.3 days for SP1 and HCG respectively and both proteins were initially secreted in approximately equivalent concentrations. However, some 30 days following the LH peak, the concentration profiles began to diverge, with SP1 levels continuing to rise whilst HCG concentrations showed the characteristic plateau at 8 and 10 weeks of gestation.

Chorionic Gonadotropin↗
PubMed1981

Effect of smoking on maternal blood SP1 levels in late pregnancy.

Maternal blood levels of pregnancy-specific beta 1-glycoprotein (SP1) were measured in 1669 samples from 1078 patients at 31 to 40 weeks' gestation. Mothers who smoked throughout pregnancy showed a general reduction in infant birth weight and blood SP1 levels. Further analysis of these findings showed that SP1 levels were directly related to fetal weight, and suggested that smoking affects fetus and placenta as a single unit.

Birth Weight↗
PubMed1981

Simplified method for measuring sex-hormone binding globulin.

We describe a simple, rapid method for measurement of sex-hormone binding globulin. Serial dilutions of pregnancy serum are prepared in serum from males that has been pre-treated by heating to 60 degrees C for 1 h to destroy endogenous binding globulin, which is then determined by a long-used technique to yield a set of "standards." In the assay itself, a fixed amount of [3H]-labeled and unlabeled dihydrotestosterone is incubated with standard or unknown, and the bound fraction precipitated with saturated ammonium sulfate. A plot of percent of the steroid bound vs standard dilution yields a sigmoid curve, from which the results in unknowns can be read by simple extrapolation. Within-assay CVs for pools of serum from men, women, and women in late pregnancy were 6.56, 9.59, and 8.4%, respectively. Between-assay CVs for the same pools were 8.05, 9.5, and 11.5%, respectively. The correlation between results obtained by this method and those of the older technique was 0.95 for samples from non-pregnant subjects and 0.73 for those from pregnant women. Our procedure is simpler and faster than previous methods and accurately measures the differences in the globulin in sera from men, women, and pregnant women. Forty to 50 samples can be assayed in a working day.

Adsorption↗
PubMed1980

Molecular heterogeneity of placental protein 5 (PP5) in late pregnancy serum and plasma: evidence for a heparin-PP5 polymer.

The apparent levels of placental protein 5 (PP5) measured by radioimmunoassay are substantially greater in serum than plasma. Using molecular sieve chromatography we have shown that PP5 exists in a number of different forms, and that in the presence of heparin or endogenous heparin-like substances PP5 forms complexes and polymers. These findings add weight to the concept that PP5 may be involved with the coagulation system and, in particular, with coagulation mechanisms in the intervillous space of the human placenta.

Chromatography, Gel↗
PubMed1980

Immunochemical and biological studies on two molecular variants of pregnancy specific beta 1 glycoprotein (SP1) SP1 alpha and SP1 beta.

Analytical crossed immunoelectrophoresis was performed to examine the relationship of a high molecular mass alpha 2 mobile glycoprotein (SP1 alpha) which is immunochemically identifiable with pregnancy specific beta 1 glycoprotein (SP1 beta). There was no evidence for any reaction of SP1 alpha with antisera to normal human serum protein, nor for complex formation following incubation with normal serum proteins. The half-life of SP1 alpha was apparently shorter than that of SP1 beta after delivery of the placenta.

Female↗
PubMed1980

Pregnancy-specific beta-glycoprotein in complications of early pregnancy.

Maternal concentrations of pregnancy-specific beta 1-glycoprotein (SP1) were measured in 145 patients with vaginal bleeding in the first trimester of pregnancy. The levels of SP1 were substantially reduced in cases in which the outcome was unsatisfactory. The sensitivity of the test was 65%, the predictive value 96%, and the specificity 98%; these results are at least as good as those biochemical tests of this type. It is concluded that measurement of SP1 is useful in diagnosis, even when ultrasound findings are also available. However, in a small group of subjects both ultrasound and biochemical findings were normal, despite an unfavourable outcome, and it seems likely that such cases are beyond the reach of any present diagnostic measure.

Abortion, Spontaneous↗
PubMed1980

Use of a rapid hCG-beta-subunit radioimmunoassay in acute gynaecological emergencies.

Chorionic gonadotrophin (hCG) was measured by a rapid and sensitive radioimmunoassay in 100 female patients with lower abdominal pain attending an emergency department. Of the 24 subjects with a positive result, 22 had evidence of pregnancy (ectopic or uterine). Of the 76 patients with negative results, 3 had some evidence of pregnancy. This test may be of considerable practical value in the differential diagnosis of acute abdominal emergencies in women of reproductive age.

Abortion, Spontaneous↗
PubMed1980

Circulating levels of placental protein 5 in the mother: relation to birth weight.

A total of 914 blood samples was obtained from an unselected population of 400 women between 36 and 40 weeks gestation. Serum PP5 levels were measured by a sensitive radioimmunoassay. After ranking of PP5 levels and birth weight the value of serum PP5 in the diagnosis of intrauterine growth retardation was examined. The sensitivity, predictive value, and specificity of the test were 17.07, 16.66, and 90.25 per cent respectively; these results suggest that serum PP5 levels are less accurate than other biochemical parameters in the identification of fetal growth retardation in late pregnancy.

Birth Weight↗
PubMed1980

Adrenal-seminal-pituitary protein levels in maternal serum and amniotic fluid.

Adrenal-seminal-pituitary protein (ASP) was measured by radioimmunoassay in maternal serum and amniotic fluid samples obtained throughout pregnancy. Levels of ASP in maternal circulation showed a steady rise from a mean of 350 micrograms/l at ten weeks gestation to 526 micrograms/l at term. There was a further rise in ASP levels during labour. In contrast, a slight decline in amniotic fluid ASP was observed throughout pregnancy but the levels rose sharply during labour. These findings are in agreement with the hypothesis that ASP is closely associated with prostaglandin physiology.

Amniotic Fluid↗
PubMed1980

Two-site immunofluorometric assay for pregnancy-specific beta 1-glycoprotein (SP1).

We describe an immunoassay for human pregnancy-specific beta 1-glycoprotein by use of fluorescein-labeled antibodies to this protein. The technique is generally similar to that of a "two-site" immunoradiometric assay but has the advantage of stability of tracer and avoidance of radiation hazard. However, the procedure requires relatively large quantities of antibody. Furthermore, the within-assay coefficient of variation (11.8%) is greater than that for radioimmunoassay (6.5%). This results from imprecision of the end-point detection, and some inherent difficulties in optimizing a "two-site" immunometric system. Concentrations of endogenous material as measured by the fluorometric assay are 1.9-fold higher than those obtained with radioimmunoassay, probably because the former detects multiple forms of this heterogeneous material.

Female↗