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Biomedical subjects

D J Brock

Publications and source records attributed to D J Brock.

At least 163 records · Page 9Linked to original sources
PubMed1981

Prenatal fetal karyotyping and maternal serum alpha-fetoprotein screening.

Prenatal karyotyping was undertaken in 569 consecutive amniotic fluid samples where the indication for amniocentesis was two sequential raised maternal serum alpha-fetoprotein concentrations. In 475 successful cultures five chromosome abnormalities were found--four constitutional anomalies (47,XXY; 47,XYY; an inherited inv(8) (p23q11); and a de-novo translocation t(6;7) (p11;p22) and a culture-derived anomaly (trisomy 2) found in amniotic fluid cells but not in the fetus aborted because it had spina bifida. Of the pregnancies complicated by constitutional abnormalities, only the pregnancy in which the de-novo translocation was detected was terminated. No chromosome abnormalities were detected in the 17 pregnancies which miscarried after amniocentesis. These results provide little justification for including fetal karyotyping as an essential part of maternal serum alpha-fetoprotein screening programmes.

Adult↗
PubMed1981

Prenatal diagnosis of exstrophy of the cloaca.

While screening for neural tub defects, three cases of exstrophy of the cloaca were found through elevated second-trimester maternal serum alphafetoprotein levels. Measurement of amniotic fluid alphafetoprotein and examination of the structure of rapidly adhering cells confirmed the abnormalities, and the pregnancies were terminated. Subsequent studies of cholinesterase isozymes by acrylamide electrophoresis showed an abnormal acetylcholinesterase band in each of the three amniotic fluids. During the same period, two more cases of exstrophy of the cloaca were identified in spontaneous abortions and another one in a stillbirth. It is suggested that the condition is more common than has been previously suspected and is often misclassified as omphalocele.

Acetylcholinesterase↗
PubMed1981

The use of amniotic fluid AFP action limits in diagnosing open neural tube defects.

An analysis is made of alphafetoprotein (AFP) concentrations in 3630 amniotic fluids submitted for prospective prenatal diagnoses over a 7-year period. There were 89 cases of anencephaly, 74 of open spina bifida and 3467 with normal singleton outcomes. The AFP data were expressed in both standard deviations above the mean and multiples of the normal median for individual weeks of gestation. False positive and false negative rates were comparable in the two systems at selected cut-offs. It is concluded that either system may be used in setting action limits for the primary distinction of unaffected pregnancies from those in which an open neural tube defect is present.

Amniotic Fluid↗
PubMed1980

Gel electrophoresis of amniotic fluid acetylcholinesterase as an aid to the prenatal diagnosis of fetal defects.

The presence of absence of a specific acetylcholinesterase (AChE) band was determined by polyacrylamide gel electrophoresis on 272 second trimester amniotic fluid samples. The AChE band was absent from 176 normal samples, including seven which had been scored as false positives by alphafetoprotein (AFP) assay. It was present in all 30 samples from open neural tube defects, of which four had been scored as false negatives by AFP assay. In remaining 66 pregnancies with abnormal outcome, an AChE band was in general present when AFP was raised and absent when it was normal. However, all six cases of congenital nephrosis had raised AFP and no AChE band, while two of 30 pregnancies ending in spontaneous abortion had an AChE band and normal AFP. These results suggest that AChE electrophoresis is a valuable confirmatory technique for the early prenatal diagnosis of fetal abnormalities.

Acetylcholinesterase↗
PubMed1980

Development of a quantitative immunoassay for the cystic fibrosis gene.

An antiserum raised in guineapigs showed positive immunoelectrophoretic reaction with sera from 16 of 17 patients with cystic fibrosis, 8 of 9 obligate heterozygotes, and only 1 of 15 normal subjects. The antiserum appeared to be specific to the cystic-fibrosis protein described by Wilson and colleagues. Precipitin peaks were larger with sera from cystic-fibrosis homozygotes than from heterozygotes, suggesting the possibility of a new quantitative biochemical assay for cystic fibrosis.

Animals↗
PubMed1980

The potential of mid-trimester maternal plasma alpha-fetoprotein measurement in predicting infants of low birth weight.

Maternal plasma alpha-fetoprotein (AFP) was measured at mid-trimester in 113 women who subsequently were delivered of a singleton liveborn infant weighing less than 2.5 kg and in 113 matched controls whose infants weighed more than 2.5 kg. Plasma AFP levels were significantly higher in the subjects than in the controls, while 10 of the subjects and only 3 of the controls had values above 2.0 times the median. The higher AFP concentrations were seen both in pregnancies in which the outcome was a small premature infant and in those in which it was a small-for-dates baby.

Female↗
PubMed1980

Pregnancy specific beta 1-glycoprotein and human chorionic gonadotrophin levels n amniotic fluid and maternal serum in the first half of pregnancy.

Pregnancy-specific beta 1-glycoprotein (PSBG) and chorionic gonadotrophin (HCG) were measured by radioimmunoassay in the amniotic fluid of 99 normal pregnancies, 19 pregnancies of women at risk of having another child with congenital nephrosis and 8 pregnancies in which the fetus had a neural tube defect. Maternal serum PSBG and HCG levels were estimated in 52 normal pregnancies and 15 pregnancies at risk for congenital nephrosis. Both amniotic fluid and maternal serum PSBG levels increased in either compartment after 14th week of pregnancy. There was a positive correlation between maternal serum and amniotic fluid PSBG concentrations (P less than 0.001), between maternal serum and amniotic fluid HCG concentrations (P less than 0.001), and between the amniotic fluid PSBG and HCG levels (P less than 0.05) at a given week of pregnancy (wk 15). On average the maternal serum PSBG level was 20-50 times and the HCG level 2-3 times the amniotic fluid level of normal pregnancies. In cases with a neural tube defect the amniotic fluid PSBG and HCG values were similar to those in normal pregnancy. In congenital nephrosis the amniotic fluid HCG concentration was higher than normal at 15-16 weeks of gestation (P less than 0.05), whereas the amniotic fluid PSBG concentration was normal. Thus, placental pathology in congenital nephrosis appears to be reflected as an increased amniotic fluid concentration of HCG in the second trimester.

Amniotic Fluid↗
PubMed1979

Significance of elevated mid-trimester maternal plasma-alpha-fetoprotein values.

In a prospective trial of 15,481 pregnancies, 667 women (4.3%) had two sequential mid-trimester plasma-alpha-fetoprotein (A.F.P.) values above 2 times the median. The outcome of these pregnancies was open neural-tube defect (12.4%), birthweight less than 2.5 kg (10.3%), twins (9.8%), fetal wastage (9.5%), perinatal death (2.6%), other (1.3%), and "normal" singleton (54.1%). At higher A.F.P. cutoffs the proportion of "normal" singleton pregnancies declined rapidly, being 19% at 3 times the median and 9% at 4 times the median. If it is assumed that ultrasonography and amniotic-fluid A.F.P. assay can detect twins and most cases of neural-tube defect, the outcome of the residual pregnancies is still strongly influenced by plasma-A.F.P. level. Thus at a cut-off of 4 times the median two-thirds of the pregnancies in this residual group will end in spontaneous abortion, stillbirth, or neonatal death. It is suggested that counselling of women taking part in A.F.P. screening programmes should be strongly influenced by maternal plasma-A.F.P. levels, even if ultrasonographic findings and amniotic-fluid levels are normal.

Birth Weight↗