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Biomedical subjects

S Barker

Publications and source records attributed to S Barker.

At least 163 records · Page 9Linked to original sources
PubMed1984

Effects of stereoisomers of estradiol on food intake, body weight and hoarding behavior in female rats.

The effects of 17-alpha and 17-beta estradiol on food intake, body weight and hoarding behavior in ovariectomised rats were investigated. For five days, ten animals received subcutaneous injections of both isomers (10 micrograms/kg/day) in a counterbalanced design. Hoarding tests were conducted on the last three days of each 5-day injection period. 17-Alpha estradiol significantly reduced food intake but was without effect on body weight. 17-Beta estradiol reduced food intake significantly more than the alpha form and also significantly reduced body weight. These differential effects suggest that stereoisomers of estradiol may be acting on separate regulatory systems. The treatments did not change hoarding activity compared to pre-treatment levels.

Animals↗
PubMed1983

Cutaneous erythematous reaction patterns.

Cutaneous erythematous reaction patterns are signs of hypersensitivity to inciting agents, both endogenous and exogenous. They include erythema multiforme, toxic epidermal necrolysis, erythema nodosum and the figurate erythemas. A thorough evaluation is often necessary to identify the provocative agent. When the cause is not discovered, it is imperative that the physician perform repeat examinations, since serious internal disorders may be associated with some of these reactions.

Adult↗
PubMed1977

Maternal serum alpha-fetoprotein and spontaneous abortion.

The relationship between spontaneous abortion and maternal serum alpha-fetoprotein (AFP) levels was investigated between 9 and 25 weeks of pregnancy. Seven out of 126 (5-6 per cent) women who had spontaneous abortions had raised maternal serum AFP levels at their antenatal booking visit compared to 4 out of 247 (1-6 per cent) control patients who were delivered of single liveborn infants, a statistically significant differences. The raised AFP concentrations were, however, associated with spontaneous abortion only if the serum samples had been taken immediately before, or at sometime after the abortion was first clinically suspected. This suggests that high levels do not predict the development of abortion in women who have not already threatened to abort. It is therefore unlikely that women who have not already threatened to abort. Therefore, when maternal serum AFP levels are used to screen for fetal neural tube defects, women referred for a diagnostic amniocentesis on account of a high level are unlikely to have been selected on the basis of a tendency to abort.

Abortion, Spontaneous↗
PubMed1976

Maternal serum alpha-fetoprotein and previous neural tube defects.

A case-control study involving 63 pregnancies showed that women who had previously had an infant with anencephaly or spina bifida did not have raised serum alpha-fetroprotein (AFP) levels in subsequent unaffected pregnancies. The value of a serum AFP determination in such women is discussed. If the serum AFP level is normal and if ultrasonography excludes anencephaly the risk of spina bifida might be low enough (about 1 per cent) to make diagnostic amniocentesis difficult to justify. Conversely, a high serum AFP value in such women should not be acted on without confirmation of an abnormality by ultrasonography and, if that is negative, by diagnostic amniocentesis.

Amniocentesis↗
PubMed1975

Effect of gestational age on screening for neural-tube defects by maternal plasma-A.F.P. measurement.

Maternal plasma or serum alpha-feto-protein (A.F.P.) concentrations were measured once between 8 and 22 weeks of gestation in each of sixty-two pregnancies which resulted in an infant with a neural-tube defect. Between 13 and 22 weeks of pregnancy twenty-two of the forty-one cases tested (54%) had A.F.P. values greater than three times the median value for unaffected pregnancies (which is equivalent to the 97th percentile of normal), and many of these values were very high indeed. However, before the 13th week of pregnancy only one of the twenty-one cases (5%) had an A.F.P. value more than three times the median for unaffected pregnancies, and this value was not very high. This indicates that in antenatal screening for anencephaly or spina bifida, A.F.P. should be measured in blood taken from the mother during the second trimester.

Anencephaly↗
PubMed1975

Maternal serum alpha-fetoprotein levels in multiple pregnancy.

Maternal serum alpha-fetoprotein (AFP) levels were higher in 10 twin pregnancies and one triplet pregnancy than in 22 control singleton pregnancies matched for maternal age, parity, and the time of gestation at which the serum sample was taken. In twin pregnancies the average AFP levels were double those found in singleton pregnancies and the level in the triplet pregnancy was even higher. Raised maternal serum AFP values due to multiple pregnancy should not cause unnecessary amniocentesis in the diagnosis of anencephaly or spina bifida if an ultrasound investigation is routinely performed first.

Adult↗
PubMedDate not supplied

Effect of erythropoietin administration on blood and plasma viscosity in hemodialysis patients.

The effect of recombinant human erythropoietin (EPO) on whole blood and plasma viscosity was studied in six anemic hemodialysis (HD) patients, and five equally anemic placebo treated HD patients. Viscosity was determined pre- and postdialysis using cone-plate viscometry. Predialysis values for hematocrit and whole blood viscosity increased significantly over a 12 week period in the EPO but not the placebo treated group; plasma viscosity did not change in either group. Whole blood viscosity measured before and after a single HD session during week 12 revealed a significant rise. This change, expressed as a percent of the predialysis values, was similar in the two groups. Thus, the rise in whole blood viscosity seen in EPO treated patients is a result of the increase in erythrocyte concentration and not a result of an effect of EPO on plasma. In addition, EPO does not seem to alter the acute effect of HD on blood viscosity.

Adult↗
PubMedDate not supplied

Internalisation of the type I angiotensin II receptor (AT1) and angiotensin II function in the rat adrenal zona glomerulosa cell.

Using a specific monoclonal antibody (6313/G2) to the first extracellular domain of the type 1 receptor (AT1), we showed that most of the receptor is internalised in the rat glomerulosa cell. When viable glomerulosa cells are incubated with 6313/G2, the receptor is transiently concentrated on the cell surface, and aldosterone output is stimulated. This stimulated output is enhanced by neither threshold nor maximal stimulatory concentrations of AII amide, although the antibody does not inhibit AII binding to the receptor. The antibody directly stimulates inositol trisphosphate (IP3) generation, but, while having no intrinsic action on protein kinase C (PKC) activation, it significantly inhibits the PKC response to angiotensin II. The data suggest that although the receptor is mostly internalized, recycling to the plasma membrane is constitutive, or regulated by unknown factors. Retention of the AT1 receptor in the membrane is alone enough to allow sufficient G protein interaction to generate maximal steroidogenic effects, through IP3 generation. PKC activation induced by angiotensin II has no bearing on steroidogenesis in the dispersed glomerulosa cell system.

Angiotensin II↗