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Biomedical subjects

H L Lau

Publications and source records attributed to H L Lau.

9 recordsLinked to original sources
PubMed1978

Early detection of human chorionic gonadotropin in urine by simple immunoassays.

Data are presented to show that human chorionic gonadotropin (hCG) in urine can be detected early in pregnancy by simple immunoassays performed prior to or around the time of the expected but missed menstrual period. Differences between the use of simple immunoassays with urine and radioimmunoassays and radioreceptor assays with serum are discussed.

Chorionic Gonadotropin↗
PubMed1978

Pitfalls and problems in the interpretation of AFP data--myths and misuse of the "normal range".

Drawing a line more intelligently for AFP data means using as a denominator two fairly well-defined populations (abnormal and normal), instead of one ill-defined normal population. The line is drawn at the intersect between two curves to minimize the error of misclassification; this replaces an arbitrarily defined cutoff level (multiples of the standard deviation unit). Moving the line to the right reduces the false positive error when screening for NTD, whereas moving the line to the left provides a sensitive alert signal for routine screening of maternal sera by AFP determinations for fetal distress. Adjustment of the line for cost and benefit factors and the use of probability statements that include the prevalence of specific conditions all help sharpen medical classification and decisions. Cross-sectional analysis is separated from longitudinal analysis. A benefit from this discussion may be the replacement of the normal range with a simple plot of AFP results or a percentile distribution, which would be more meaningful and more easily understood by all.

Costs and Cost Analysis↗
PubMed1977

A capillary tube pregnancy test.

The experience with a new, simple, and sensitive capillary tube pregnancy test requiring no refrigeration is described. The results of this test and other tests are compared against histologic results. The 1/2 unit capillary test, defined as having a sensitivity of 0.5 I.U. of HCG per milliliter, had a higher percentage of agreement with histopathologic results (99.65 per cent) than all other tests studied. The false-positive rate was 0.07 per cent and the false-negative rate was 0.28 per cent. In this series of 1,486 tests, 21 cases of pregnancy, identified by a 1/2 unit test, were missed by one or two unit tests. The earliest detection of pregnancy by the 1/2 unit capillary test confirmed by histology was 3 weeks from the last menstrual period (four cases).

Adolescent↗
PubMed1976

Alpha-fetoprotein.

Despite all the information about AFP presented, a great deal still needs to be discovered especially in pregnancy. Geographical and racial differences remain to be elucidated. Similarly, differences in obstetric population in Helsinki and Baltimore, for example, are only now being studied. Sex differences may exist; Lardinois and associates195 cited a higher level of AFP in male than female fetuses. The important questions that need to be answered are whether AFP assays can help improve the other half of prenatal care- that directed to the fetus- and whether the AFP model can help enhance our understanding of the similarities and differences of fetal and cancer cells.

Abnormalities, Multiple↗
PubMed1975

Menstrual extraction.

This report documents the clinical outcome of 137 consecutive menstrual extractions. The pre- and postprocedural pregnancy testing is correlated with histologic examination of tissue obtained. This report reviews the management of the unsuccessful cases.

Abortion, Induced↗
PubMedDate not supplied

Further experience with a capillary tube pregnancy test.

Further evaluation of the nonrefrigerated capillary tube pregnancy test is presented. A 127-mm by 2-mm glass capillary tube containing lyophilized antibody to human chorionic gonadotropin and latex indicator particles is used. Urine is drawn into the tube by capillary action; then, the tube is tilted to allow the urine to dissolve the antibody and to suspend the latex particles. The test results are read after a one-hour incubation period. Test results were evaluated against histopathologic and clinical data. Special efforts were made to stress the false-positive rate of the test by tripling the number of negative cases and doubling the sample size. A 99.82% agreement, a 0.18% false-negative rate and a 0% false-positive rate were obtained. In 52 confirmed pregnancies, the more sensitive capillary test detected human chorionic gonadotropin, whereas the commercial tests did not. Human chorionic gonadotropin was also detected one week earlier than reported in the first series.

Antibodies↗