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Biomedical subjects

R H Buck

Publications and source records attributed to R H Buck.

24 records · Page 2Linked to original sources
PubMed1987

Bedside application of an ultrasensitive urine test for HCG in patients with suspected ectopic pregnancy.

One hundred and seven patients with suspected ectopic pregnancy were tested for HCG at the bedside using the Tandem Icon. The test was performed by ward doctors with no formal laboratory experience. The patients were managed conservatively or by surgery as dictated by the clinical picture and the Icon test result. Retrospective categorisation of the 107 patients by laboratory analysis and clinical outcome showed that 21 were pregnant (17 ectopic, 4 intrauterine) and 86 non-pregnant. At the bedside the Icon was reported as negative in one pregnant patient and three patients who were not pregnant were found to give Icon-positive results. In the laboratory the Icon correctly categorised all patients. Three of the four discrepant results were found to be a direct result of the operator's inexperience in analytical procedure and interpretation. The Tandem Icon HCG urine assay can reliably be used at the bedside of patients with suspected ectopic pregnancy provided that the operator has had sufficient experience in its use.

Chorionic Gonadotropin↗
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

Measurement of the free alpha subunit of human glycoprotein hormones by a monoclonal antibody-based immunoradiometric assay, and further exploration of antigenic sites on the choriogonadotropin molecule.

Three monoclonal antibodies were raised against the free alpha subunit of choriogonadotropin (hCG); each recognized a different antigenic site on the molecule. One (antibody 42) preferentially bound to the alpha subunit when it was coupled to the beta subunit as dimeric choriogonadotropin (hCG), thyrotropin (TSH), lutropin (LH), or follitropin (FSH). Antibody 71 showed some cross-reaction with intact FSH; antibody 75 was more specific for the alpha subunit. All were of low affinity (10(-7) to 10(-8) mol/L), but when combined in immunoradiometric assays (IRMAS) they proved to be as sensitive as current radioimmunoassays involving polyclonal antibodies. Advantages of the combination of antibody 75 bound to the solid phase and antibody 71 as the radiolabeled antibody were: detection limit of at least 0.1 micrograms/L; linear dilution of serum and urine; insignificant cross-reaction with intact hCG, allowing direct assay in pregnancy fluids; and a coefficient of variation less than 3% over the reference interval for nonpregnant women. There was 4% cross-reaction with intact FSH, suggesting that the epitopes recognized by nos. 71 and 75 are more exposed in FSH and that perhaps there is less folding in this molecule than in intact hCG.

Animals↗
PubMed1986

Various methods for determining urinary choriogonadotropin evaluated for the early diagnosis of ectopic pregnancy.

We evaluated the accuracy, sensitivity, specificity, and performance characteristics of seven methods for determining urinary choriogonadotropin in the early diagnosis of ectopic pregnancy in 46 patients with gynecological emergencies. The kits examined included immunoenzymometric assays (Tandem Icon hCG, Model Plus, Diapreg-25, Pregnastick, Nimbus) and reverse hemagglutination inhibition assays (NeoPregnosticon 75 Duoclon, Pregtest). We found immunoenzymometric assays to be the most sensitive procedures (lowest detection limits) for qualitatively detecting hCG secreted by ectopic pregnancy. We concluded that the Tandem Icon best meets our criteria and we advocate its use in the emergency room or ward as the first-line investigation of ectopic pregnancy. In addition, the use of Diapreg-25 has many theoretical advantages as an extremely sensitive index of choriogonadotropin status because of its ability to detect very low concentrations of beta subunit.

Chorionic Gonadotropin↗