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Biomedical subjects

T Chard

Publications and source records attributed to T Chard.

At least 217 records · Page 12Linked to original sources
PubMed1988

Immunoreactive human chorionic gonadotrophin from the cyst fluid and CSF of patients with craniopharyngioma.

A specific radioimmunoassay for the beta-chain of human chorionic gonadotrophin irHCG beta has demonstrated HCG-like material to be present in craniopharyngioma cyst fluid in nine consecutive patients with craniopharyngioma. There was no detectable LH/HCG bioactivity as assessed using testosterone production from isolated Leydig cells from rat testis in seven samples tested. One patient was also found to have measurable irHCG beta in the cerebrospinal fluid (CSF), which fell to undetectable levels following surgery; in this patient, there was clinical evidence that the cyst fluid had leaked into the CSF pre-operatively. Immunocytochemical staining for HCG beta and intact HCG was positive in five of the tumours. irHCG beta was not measurable in the serum of any of the patients.

Biological Assay↗
PubMed1988

Circadian variation of GH-independent IGF-binding protein in diabetes mellitus and its relationship to insulin. A new role for insulin?

Evidence is accumulating that a non-GH dependent insulin-like growth factor-binding protein (IGF-BP) is not only a carrier protein but also has an active role in the growth process. We have measured levels of this IGF-BP, using a specific RIA, over 12 or 24-h periods in 11 adolescents with diabetes mellitus and five normal adults. In each of the normal the IGF-BP was undetectable for most of the day but with a broad nocturnal peak observed, with levels up to 50 micrograms/l. The levels of IGF-BP were unrelated to the secretory pattern for GH but correlated inversely with the concentration of circulating insulin. In the diabetics a very similar pattern was observed, but with detectable levels throughout the day and much higher peak levels seen at night. Peak levels were up to 120 micrograms/l if a long-acting insulin preparation was administered in the evening but were 400-500 micrograms/l if the long-acting preparation was administered in the morning. The IGF-BP was strongly correlated with plasma glucose in this latter group. In a further group of diabetics overnight profiles were obtained on two separate nights, a normal night and a night with euglycaemia maintained with a glucose clamp technique. Euglycaemia failed to affect peak levels of the binding protein, although the shape of the nocturnal peak was altered consistent with the altered pattern of circulating free insulin. In this group a strong inverse correlation was obtained between the IGF-BP and free insulin levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Plasma cortisol and adrenocorticotropin in appropriate and small for gestational age fetuses.

Plasma cortisol and adrenocorticotropin (ACTH) were measured in fetal blood samples obtained by cordocentesis from 61 appropriate for gestational age (AGA) and in 41 small for gestational age (SGA) fetuses at 18-38 weeks gestation. Fetal plasma cortisol (mean 74 nmol/l) did not change but plasma ACTH increased between 18 and 36 weeks gestation and the two were not significantly correlated. Plasma cortisol in cord blood samples after vaginal delivery at term (mean 305 nmol/l) was higher than in samples at elective cesarean section (mean 151 nmol/l), and there was a significant correlation between fetal and maternal levels. The findings suggest that in human fetuses a late gestational rise in plasma cortisol may not be necessary for organ maturation and that the high fetal plasma cortisol in spontaneous labor at term is probably the result rather than the cause of labor. In SGA fetuses, plasma cortisol was higher and ACTH lower than in AGA fetuses, and plasma cortisol was inversely correlated to fetal hypoglycemia, suggesting that in the chronically hypoglycemic SGA fetus the fetal pituitary is under negative inhibition.

Adrenocorticotropic Hormone↗
PubMed1988

Ultra rapid blood sampling for the determination of short-term variations in the circulating concentration of oestradiol in man.

Blood was taken from three healthy female and three healthy male volunteers every 20 s for 15 min. The serum level of oestradiol was measured and the pattern of variation assessed by a cusum plot of the sequential data, by autocorrelation of the detrended serial data, and by looking for pulses. In two cases the variation in oestradiol values was greater than that which could be attributed to variation in the assay. Both these subjects showed a significant overall change in values during the sampling period (an increase and a decrease). There was no trend in the remaining four subjects. In two of the six subjects there was significant autocorrelation of detrended sequential levels. Defining a 'pulse' as three times the assay coefficient of variation no more pulses were identified than was expected from random fluctuations. By frequency analysis the two subjects with significant autocorrelation showed periodic fluctuations of approximately 70/h and 9/h respectively. It is apparent that both the rate of sampling and the method of analysis greatly influence the evaluation of pulsatile release of oestradiol.

Adult↗
PubMed1987

Human versus machine: a comparison of a computer 'expert system' with human experts in the diagnosis of vaginal discharge.

A model system has been designed which generates 'cases' of vaginal discharge. Each such case is presented to a human for diagnosis, and this is then compared with a computer diagnosis using two forms of Bayes' theorem. Six subjects (2 medical; 4 non-medical) participated in the trial and each examined 100 successive 'cases'. When the humans had forewarning of the trial and full access to the knowledge-base their performance was superior to that of Bayes' theorem using positive features only and equivalent to that using both positive and negative features. When the trial was repeated without forewarning the human performance was markedly inferior to that of the machine. It is concluded: that human and computer-aided diagnosis can be of approximately equal efficiency for complex and non-definitive data; that the imperfections of human memory give an obvious potential advantage to the machine in this type of situation.

Computer Simulation↗
PubMed1987

In vitro secretion of human chorionic gonadotrophin by bladder tumour cells.

Human chorionic gonadotrophin (hCG) and alphafetoprotein (AFP) were measured in culture media from a panel of 29 cell lines including 9 bladder carcinomas, 5 'normal' bladder epithelia, 10 germ cell tumours, and 5 miscellaneous tumours and 'normal' cell lines. In 7 of the 9 bladder carcinomas and 4 of the 5 'normal' bladder epithelia, the media contained hCG at levels ranging from between 34 and 3,600 IU l(-1). All other cell lines, including the 10 germ cell tumour lines gave negative results for hCG. These findings indicate that in vitro secretion of hCG is a common feature of normal and neoplastic bladder transitional epithelia, and support the hypothesis that parts of the genito-urinary epithelium have a potential for hCG production.

Cell Line↗
PubMed1987

Saliva levels of oestradiol and progesterone in relation to non-protein-bound concentrations in blood during late pregnancy.

Serum and saliva samples were obtained from 25 women in the last eight weeks of pregnancy. The concentrations of oestradiol and progesterone were measured by radioimmunoassay. The proportion of each hormone which was not bound to protein in serum was measured by centrifugal ultrafiltration: for progesterone the unbound fraction was 2.5% (2.13--2.78%) and for oestradiol 1.27% (1--1.83%). There was only a weak relationship between the free hormone concentrations estimated in blood and the levels measured in saliva. We conclude that, for the situation examined here, saliva does not provide a useful measure of unbound, biologically active steroid.

Estradiol↗
PubMed1987

Androgen suppression by hydrocortisone without aminoglutethimide in orchiectomised men with prostatic cancer.

The effects of hydrocortisone (HC) alone and in combination with aminoglutethimide (AG) have been studied on circulating blood levels of androgens in orchiectomised men with metastatic prostatic cancer. Serum testosterone levels were significantly lower in both early and late hydrocortisone-treated patients compared with pre-treatment levels. The regimen of HC + AG increased serum testosterone almost back to pre-treatment levels. Similar observations were noted with serum androstenedione, dehydroepiandrosterone sulphate and sex hormone binding globulin (SHBG) levels. Clinical responses to hydrocortisone alone have been observed in this series of patients. It is concluded that aminoglutethimide has no place in the therapy of prostatic cancer and that physiological doses of hydrocortisone represent the best second hormonal manoeuvre for prostatic cancer patients.

Aged↗
PubMed1987

Relationship between maternal and fetal corticotrophin-releasing hormone-41 and ACTH levels in human mid-trimester pregnancy.

Samples of maternal blood, amniotic fluid and umbilical arterial and venous blood were collected from 11 women at 16-24 weeks of pregnancy. Corticotrophin-releasing hormone-41 (CRH-41) and ACTH were measured by immunoradiometric assay. The mean levels of ACTH were 11 pmol/l in maternal plasma, 12 pmol/l in fetal plasma and 9.7 pmol/l in amniotic fluid. The mean levels of CRH-41 were 1.6 pmol/l in maternal plasma and 0.7 pmol/l in fetal plasma. There was a positive correlation between maternal and fetal plasma CRH-41 and between maternal CRH-41 and ACTH. In fetal plasma there was a weak inverse correlation between CRH-41 and ACTH. This is the first demonstration of CRH-41 in the circulation of the mid-trimester human fetus, but on the basis of the present findings it is not possible to specify the exact source (fetal, placental or maternal).

Adrenocorticotropic Hormone↗
PubMed1987

A relationship between sex hormone binding globulin and dehydroepiandrosterone sulfate in normally menstruating females.

Blood samples were collected from 120 normally menstruating women throughout the menstrual cycle. Serum was assayed for sex hormone binding globulin (SHBG), dehydroepiandrosterone sulfate (DHEAS), estradiol (E2) and testosterone (T). There was an inverse relationship between SHBG and DHEAS, but no relationship between T or E2 and SHBG levels. There is at present no model which readily explains this inverse relationship between SHBG and DHEAS in normal subjects.

Adolescent↗
PubMed1987

Relationship between blood and urine concentrations of intact human chorionic gonadotropin and its free subunits in early pregnancy.

Paired blood and urine samples were obtained from patients between the sixth and 14th weeks of normal pregnancy. The levels of intact human chorionic gonadotropin (hCG), and of the free alpha and beta subunits, were measured by specific immunoassays. There was a close association between blood and urine levels of intact hCG and of the alpha subunit of hCG, but no relation between the levels of beta subunit in these sites. These findings suggest that the use of "beta subunit" assays may give discrepant results according to the fluid examined. By contrast, measurement of intact hCG appears to give similar results in blood and urine.

Chorionic Gonadotropin↗
PubMed1987

Early pregnancy factor.

There have been many attempts to develop a test which can detect a pregnancy between the time of fertilization and the time of implantation. The subject of this review is Morton's "early pregnancy factor", a complex immunological phenomenon which is said to become positive within hours of fertilization. However, many workers have been unable to reproduce these findings and the experimental methods have been severely criticized. Substantial further work is needed before a test of this type can be regarded as suitable for routine clinical practice, if indeed it will ever be possible.

Chaperonin 10↗
PubMed1986

Placental protein 14 (PP14) in late pregnancy.

Placental protein 14 (PP14) was measured in 496 women in the last four weeks of pregnancy. There was no correlation between PP14 levels and the sex of the child, parity, age, or birthweight. A slight reduction in the median value was noted in pregnancies complicated by hypertension.

Adult↗