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Biomedical subjects

T Chard

Publications and source records attributed to T Chard.

At least 325 records · Page 18Linked to original sources
PubMed1979

The radioimmunoassay of placental protein 5 and circulating levels in maternal blood in the third trimester of normal pregnancy.

A radioimmunoassay has been developed for placental protein 5 (PP5), a product of the human placenta. Circulating concentrations of PP5 were measured in the third trimester of normal pregnancy in 400 women. Concentrations of PP5 showed a skewed distribution and rose progressively to reach a plateau in the last four weeks of pregnancy. The development of this assay will permit studies on the potential clinical application of maternal PP5 levels during normal and abnormal pregnancy.

Cross Reactions↗
PubMed1979

Maternal serum alpha-fetoprotein levels as an index of fetal risk.

In a prospective study on an obstetric population (1,059 cases) an association was found between elevated levels of maternal serum AFP at weeks 16 to 22 and the occurrence of premature labor or the need for emergency cesarean section in the third trimester. There was no association with other late fetal complications including perinatal death, perinatal asphyxia, and intrauterine growth retardation. The sensitivity of the test in respect of premature labor was 14 per cent but the high incidence of false-positive results reduces the practical value of the test.

Cesarean Section↗
PubMed1979

Molecular heterogeneity of pregnancy specific beta 1 glycoprotein: the effect on measurement by radioimmunoassay and electroimmunoassay.

A comparison of methods for the quantification of circulating pregnancy specific beta 1 glycoprotein in late pregnancy was performed to assess the influence of the presence of a high molecular weight glycoprotein with alpha 2 electrophoretic mobility (SP1 alpha) which is immunochemically identifiable with pregnancy-specific PBETA 1 glycoprotein (SP1 beta). Serum samples from 47 volunteers in the 3rd trimester of pregnancy were subjected to measurements of pregnancy specific beta 1 glycoprotein in rocket immunoelectrophoresis, quantitative crossed-immunoelectrophoresis and radioimmunoassay. Rocket immunoelectrophoresis gives a result which reflects the total SP1 content, i.e. SP1 alpha and SP1 beta while quantitative crossed-immunoelectrophoresis permits differentiation between the two molecules. Radioimmunoassay predominantly measures authenic SP1, i.e. SP1 beta in the presence of physiological amounts of SP1 alpha.

Chromatography, Gel↗
PubMed1979

Circulating levels of pregnancy proteins in early and late pregnancy in relation to placental tissue concentration.

The concentrations of human chorionic gonadotrophin (hCG), human placental lactogen (hPL), pregnancy specific beta 1 glycoprotein (SP1), ferritin (PP2) and placental protein 5 (PP5) were examined in maternal serum and placental tissue in early and late pregnancy. The circulating concentration of hPL, SP1, and PP5 were higher during late pregnancy than early pregnancy, that of hCG lower, and ferritin (PP2) levels showed no difference. Placental tissue levels of hPL and SP1 were higher in late pregnancy, hCG levels lower, and ferritin (PP2) and PP5 showed no change. The ratio of the concentration in maternal serum to that in placental tissue increased during pregnancy for all proteins with the exception of ferritin. It is proposed that the mechanism of secretion of trophoblast specific proteins varies widely and that this should be taken into account in the clinical interpretation of circulating levels in the mother.

Chorionic Gonadotropin↗
PubMed1979

The relation between the concentration of placental specific proteins in retroplacental and peripheral blood.

Concentrations of four placental proteins: human placental lactogen (hPL), placental protein 5 (PP5), pregnancy specific beta 1 glycoprotein (SP1) and human chorionic gonadotrophin (hCG), and a normal serum component, alpha 2 macroglobulin, were measured in the peripheral circulation and in blood obtained from the retroplacental space in 20 women at term delivery. Levels of hPL and PP5 were higher in the retroplacental blood than in the peripheral circulation in all patients. By contrast, levels of SP1 and hCG were consistently lower in retroplacental blood than in the peripheral circulation. Similarly, levels of alpha 2 macroglobulin were lower in the retroplacental blood. It is suggested that this 'reverse' gradient is a technical arterfact. These findings are discussed in relation to synthesis of placental proteins in a site distal to the retroplacental space, and the introduction of a technical artefact in the collection of samples.

Chorionic Gonadotropin↗
PubMed1979

Disappearance of pregnancy-specific beta 1 glycoprotein from the maternal circulation after delivery.

It is likely that there are systematic differences between circulating pregnancy-specific beta 1 glycoprotein (SP1) levels measured by radioimmunoassay and immunoprecipitation systems. We have re-investigated the decline in circulating levels of SP1 following delivery of the placenta. Serial blood samples were collected for 120 hours from 10 women following Caesarean section or vaginal delivery at term. The apparent half-life of SP1 after delivery ranged between 17 and 45 hours.

Female↗
PubMed1979

Placental protein 5 in fetal and maternal compartments.

Placental protein 5 is produced by the syncytiotrophoblast and secreted into the maternal peripheral circulation reaching levels of approximately 30 micrograms per litre in normal pregnancy at term. In the present study the distribution of PP5 was examined in maternal and fetal compartments in 13 patients at delivery.

Amniotic Fluid↗
PubMed1979

Circulating levels of pregnancy specific beta 1 glycoprotein in late pregnancy: nyctohemeral and day-to-day variation, and variation during labour.

Circulating levels of pregnancy-specific beta 1 glycoprotein have been determined in a number of physiological situations in late pregnancy. The apparent variation in five subjects studied over a 24-hour period was not in excess of that due to the assay. Excess variation was apparent in 2 of 11 subjects studied daily for up to 8 days, and in 6 of 16 patients studied serially during labour.

Circadian Rhythm↗
PubMed1979

Circulating levels of pregnancy specific beta 1 glycoprotein in pregnancies complicated by diabetes mellitus.

Circulating levels of SP1 were measured in 20 insulin dependent diabetic women during the third trimester of pregnancy. With one exception, SP1 levels were between the 80 per cent confidence limits of the normal range. The exception was a patient who was delivered of a normal infant at 37 weeks but had consistently low levels of SP1 from 32 weeks until delivery, suggesting a specific defect in SP1 synthesis.

Female↗
PubMed1979

Adrenocorticotrophin-related peptides in adult and foetal sheep pituitary glands.

Differences in foetal and adult adrenal function may be due to qualitative as well as quantitative changes in the pituitary corticotrophic stimulus. Pituitary glands from adult and foetal sheep were freshly dissected and stored at -70 degrees C until extracted at pH 1.5. The extracts were subjected to chromatography on Sephadex G-100 superfine and fractions were assayed by multiple radioimmunoassays directed against the NH2- and CO2H-terminal sequences of ACTH and lipotrophin (LPH). Peaks corresponding to beta-melanocyte-stimulating hormone (beta-MSH), beta-LHP, gamma-LPH, beta-endorphin and ACTH were identified, with little or no evidence for the presence of alpha-MSH and corticotrophin-like intermediate lobe peptide. Three peaks of large molecular weight material, A. B and C, were identified and their relative proportions shown to be considerably greater in the foetus than in the adult. The immunoassay profile of peaks A and B suggested that they were 'stem hormones' which could give rise to a family of biologically active peptides. Since the 'family tree' which they engender varies according to the stage of development, it is proposed that the changes in the 'trophic family' may explain the different adrenal responses of the foetal and adult sheep.

Adrenocorticotropic Hormone↗
PubMed1979

Changes in the concentration of 5-methoxytryptophol in the circulation at different phases of the human menstrual cycle.

The pineal indole 5-methoxytryptophol (ML) has been shown to have an antigonadal activity when administered to experimental animals, but data on its normal pattern of secretion have been lacking. Using a new gas chromatography-mass spectrometry assay, the concentration of ML at various phases of the human menstrual cycle has been studied. Daily samples were obtained throughout the month from five women with a normal cycle and two women taking an oral contraceptive. In women with a normal cycle levels of ML were found to be significantly lower in the last third of their cycle; this change was not seen in women taking an oral contraceptive who had low levels throughout the month. The changes in concentration of ML did not correlate with the changes in concentration of gonadotrophins.

Adult↗
PubMed1979

Identification and purification of a new protein from water-soluble extracts of human adrenal gland.

An homogenate of human foetal adrenal gland was subjected to negative immunoabsorption by column chromatography using anti-whole human serum coupled to Sepharose 4B. Two peaks were eluted and used to immunize rabbits. The antisera produced were absorbed and tested for specificity by double immunodiffusion. Two antigens, which appeared to be specific to the adrenal gland, were identified having molecular weights of 25 000 and 65 000 as determined by gel filtration. The lower molecular weight antigen was isolated by physicochemical methods and found to be a protein. The amino acid composition is reported.

Adrenal Glands↗