Biomedical subjects
Publications and source records attributed to J A Canick.
Prenatal screening using the maternal serum markers alpha-fetoprotein, human chorionic gonadotropin, and unconjugated oestriol was investigated in a native Japanese population. Comparison with a Caucasian U.S. population revealed differences which led to modification of the generally used equations for risk calculations. Prenatal screening was shown to be clinically useful.
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OBJECTIVE: To examine the predictive value of amniotic fluid (AF) insulin at 14-20 weeks' gestation for subsequent gestational diabetes and macrosomia in unselected gravidas 35 years or older at time of genetic amniocentesis. METHODS: We identified 296 pregnancies through stored AF samples from genetic amniocenteses (collected March 1987 through August 1992) in women meeting the following criteria: age 35 years or older, amniocentesis at 14-20 weeks, performance of a 50-g glucose challenge test, and adequate delivery data. RESULTS: A modified double-antibody radioimmunoassay reliably measured AF insulin with a detection limit of 0.35 microU/mL. Pregnant women in whom gestational diabetes was later diagnosed had higher median AF insulin levels than women who did not (0.60 versus 0.42 microU/mL, respectively; P = .026). A stepwise logistic regression analysis of gestational age at amniocentesis, maternal second-trimester weight, maternal age, and log AF insulin value on gestational diabetes showed only AF insulin to have a significant association with gestational diabetes (P = .004). Seven of 21 cases of gestational diabetes had AF insulin values exceeding the 95th percentile (1.33 microU/mL) compared with only 14 of 275 women with normal glucose tolerance (P < .001). Amniotic fluid insulin did not predict macrosomia in either nondiabetic or gestational diabetic pregnancies. CONCLUSION: Gestational diabetes is associated with increased AF insulin at 14-20 weeks, suggesting augmentation of fetal insulin production in the early fetal period in at least some cases of gestational diabetes.
OBJECTIVE: Our purpose was to determine the effects of fetal number, various ovulation induction treatments, and placental hormones on the concentration of maternal serum relaxin. STUDY DESIGN: The concentrations of relaxin, human chorionic gonadotropin, estriol, and alpha-fetoprotein were determined in blood samples drawn at 16 to 18 weeks for prenatal diagnosis in 72 singleton and 115 twin pregnancies and analyzed by one-way analysis of variance, correlation analysis, and stepwise multiple linear regression of the log-transformed data. RESULTS: The maternal serum concentrations of each of the four measured hormones were significantly higher in the twin pregnancies than in the singleton pregnancies: 1.4-fold for relaxin, 1.9-fold for human chorionic gonadotropin, 1.9-fold for estriol, and 2.2-fold for alpha-fetoprotein (all p < 0.01). The concentrations of each of the four hormones were significantly correlated with each of the others and with the number of fetuses (p < 0.01), except that estriol was not significantly correlated with human chorionic gonadotropin. The serum relaxin concentration in twin pregnancies after treatment with follicle-stimulating hormone and luteinizing hormone (menotropins) (n = 10) was 3.3-fold that in twins resulting from spontaneous ovulation (n = 89, p < 0.01). In twins resulting from in vitro fertilization or gamete intrafallopian transfer (n = 9) the serum relaxin concentration was 2.6-fold higher than in twins resulting from spontaneous ovulation (p < 0.01). The effect of clomiphene citrate (1.2-fold, n = 7) failed to reach statistical significance. CONCLUSIONS: The second fetus causes a 1.4-fold increase in the concentration of maternal serum relaxin in twin pregnancies. Induction of ovulation with menotropins causes an additional 3.3-fold increase, whereas in vitro fertilization or gamete intrafallopian transfer treatment causes an additional 2.6-fold increase over that seen in twin pregnancies that followed spontaneous ovulation.
5alpha-Reductase is the steroidogenic enzyme which reduces testosterone to 5alpha-dihydrotestosterone. In the human two different enzymes have been described, 5alpha-reductase 1 and 2. The present investigations were undertaken to determine whether 5alpha-reductase 1 and 2 were expressed in the human ovary, and to determine the relative activity of the two enzymes in various ovarian tissues. The ovary apparently expressed mRNA for only 5alpha-reductase 1, whereas the foreskin expressed both 5alpha-reductase 1 and 2. We compared the 5alpha-reductase activity at both pH 5.5 (optimum for 5alpha-reductase 2 activity) and 8.0 (optimum for 5alpha-reductase 1 activity). 5alpha-reductase activity of foreskin at pH 5.5 was 3900 times higher than small follicles, 1500 times higher than ovarian stroma, and 240 times higher than corpora lutea (all P < 0.01). 5alpha-reductase activity of corpora lutea at pH 5.5 was 17-fold higher than that of follicles (P < 0.01) and 6.5-fold higher than that of ovarian stroma (P < 0.05). 5alpha-Reductase activity of foreskin at pH 8.0 was 93 times higher than small follicles, 51 times higher than corpora lutea, and 170 times higher than ovarian stroma (all P < 0.01). The ratio of 5alpha-reductase activity at pH 5.5 to that at pH 8.0 was higher in foreskin than in corpus luteum (P < 0.05), ovarian stroma (P < 0.01), or ovarian follicles (P < 0.01). The ratio was lower in ovarian follicles than in stroma or corpus luteum (both P < 0.05).
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OBJECTIVE: To determine the levels of various biochemical forms of the placental protein, inhibin (total inhibin, inhibin A, and alpha inhibin precursor) and activin in maternal serum samples from fetal Down's syndrome, and to determine which of these analytes most effectively identifies samples from affected pregnancies. METHODS: Maternal serum samples were collected from 100 unaffected pregnancies and 20 cases of fetal Down's syndrome during gestational weeks 15-20 for routine triple marker screening, and were stored frozen after clinical assay. Levels of inhibin A, total inhibin, alpha inhibin precursor (pro-alphaC), and activin were compared retrospectively in the Down's syndrome cases and control samples. RESULTS: There was no association of the inhibin or activin levels with gestational age or length of freezer storage, and therefore single median values were determined for the unaffected pregnancies for each analyte. Multiples of the unaffected median (MoM) values were calculated for all cases, showing that inhibin A (1.95 MoM) provided the best discrimination between cases and controls, followed by total inhibin (1.37 MoM). Mann-Whitney U analysis showed significant group differences in inhibin A (P = 0.0001) and total inhibin (P = 0.0005). In contrast, alpha inhibin precursor (0.81 MoM) and activin (1.16 MoM) levels in Down's syndrome cases were not significantly different from those in unaffected patients. CONCLUSIONS: Levels of inhibin A and total inhibin, but not alpha inhibin precursor or activin, are significantly raised in maternal serum from cases of fetal Down's syndrome. These data, taken together, indicate that inhibin A levels are specifically raised in Down's syndrome pregnancy. 45% of the inhibin A levels in the Down's syndrome samples were above the 90th centile of unaffected levels, indicating that inhibin A may be as good a marker as human chorionic gonadotrophin, the most informative serum marker currently in use.
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OBJECTIVE: To determine if serum inhibin concentrations are lower in ectopic (EP) versus intrauterine pregnancies (IUPs) that are conceived spontaneously. DESIGN: Case-control study. SETTING: Academic clinical practice. PATIENTS: Serum samples were obtained from 19 women who had EP confirmed at surgery and by pathology. For comparison, serum samples were collected from 24 women of similar chronological and gestational age with sonographic evidence of an IUP. MAIN OUTCOME MEASURE: Serum dimeric inhibin-A, total inhibin, P, and hCG. RESULTS: Serum total and dimeric inhibin concentrations in women with EP were < 60% of the concentrations for women with single IUPs. Total inhibin, but not dimeric inhibin-A, was elevated in maternal serum before week 8 of gestation relative to normal menstrual cycle levels. CONCLUSIONS: Serum inhibin concentrations are lower in EP as compared with IUPs that are spontaneously conceived and the relative amounts of dimeric inhibin-A, B, and alpha inhibin subunit in maternal serum may change throughout gestation.
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Nine centres collaborated to examine the feasibility of a screening method for trisomy 18 that was based on assigning individual risk, using a combination of maternal age and measurements of alpha-fetoprotein (AFP), unconjugated oestriol (uE3), and human chorionic gonadotropin (hCG). Second-trimester measurements of these analytes were obtained from 94 trisomy 18 pregnancies. In the 89 pregnancies without an associated open defect, the median levels for AFP, uE3, and hCG were 0.65, 0.43 and 0.36 multiples of the unaffected population median, respectively. The strongest individual predictor of risk for trisomy 18 was uE3, followed by hCG, AFP, and maternal age, in that order. Using a method of individual risk estimation that is based on the three markers and maternal age, 60 per cent of pregnancies associated with trisomy 18 would be detected at a risk cut-off level of 1:100, with a false-positive rate of about 0.2 per cent. One in nine pregnancies identified as being at increased risk for trisomy 18 would be expected to have an affected pregnancy. This risk-based screening method is more efficient than an existing method that is based on fixed analyte cut-off levels. Even though the birth prevalence of trisomy 18 is low, prenatal screening can be justified when performed in conjunction with Down syndrome screening and when a high proportion of women offered amniocentesis have an affected fetus.
Urinary gonadotropin peptide (UGP; beta-core fragment), a major metabolite of human chorionic gonadotropin (hCG), was shown recently to be markedly elevated in Down syndrome pregnancy between 19 and 22 weeks of gestation. To confirm and extend this finding, we obtained maternal urine and matching maternal serum samples from 14 cases of Down syndrome and six other aneuploidies between 17 and 21 weeks of gestation. UGP was measured in all these samples and in 91 singleton control urines. Results were corrected for urinary creatinine level and expressed as multiples of the control median (MOM). hCG levels were assayed in all serum samples from the cases and compared with previously established reference values. The median UGP level in Down syndrome cases was 5.34 MOM (range 2.71-12.57); 88 per cent of the values were above the 95th centile of control levels after modelling. The median maternal serum hCG level for the same cases was 2.20 MOM (range 0.84-3.40); 36 per cent of the values were above the 95th centile. The level of UGP in every case including all other aneuploidies was higher than the comparable maternal serum hCG level. Elevated UGP measurements are strongly associated with fetal Down syndrome during the second trimester and could contribute to improved Down syndrome screening protocols that are more accessible and less expensive than are currently available.
Placental sulfatase deficiency is an X-linked metabolic defect that occurs in about 1 in 2,000 to 5,000 males. It is associated with congenital ichthyosis. In this report, the authors document a case of placental sulfatase deficiency detected during routine prenatal screening of maternal serum by the triple test: serum alpha-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG). At 16-weeks gestation, her AFP was 20.9 IU/mL (multiple of the median [MOM] 0.83), hCG was 14.4 mIU/L (MOM 0.42) and her uE3 was 0.01 nmol/L (MOM 0.01). The extremely low uE3 indicated a possible placental sulfatase deficiency, congenital adrenal hypoplasia, or other unknown abnormality. On receiving this information, the obstetrician obtained a family history that was consistent with ichthyosis in the maternal grandfather and his siblings. Biochemical analysis of placenta documented the lack of sulfatase activity. This case illustrates that an extremely low level of maternal uE3 should prompt investigation of the family for evidence of X-linked ichthyosis associated with placental sulfatase deficiency.
Both a cross-sectional and a longitudinal study were performed to investigate whether or not the collection time should be taken into consideration when generating a patient's risk for fetal Down syndrome with multiple marker screening. Diurnal variations of third-trimester alpha-fetoprotein (AFP) levels and first-trimester human chorionic gonadotropin (hCG) levels have been previously reported. In addition, large episodic fluctuations of conjugated and unconjugated oestriol (uE3) as well as a diurnal variation have also been reported in the third trimester. If the levels of these analytes routinely fluctuate during the day, they could affect a patient's risk calculation for fetal Down syndrome. The longitudinal study evaluated ten non-diabetic women who underwent sequential sampling for AFP, hCG, and uE3. The cross-sectional study evaluated 1953 patients for these three markers whose time of sampling was recorded between 8.00 a.m. and 5.59 p.m. Using either study design, no significant effect was seen in the median MOM levels of the screening analytes as a function of the time of day.
OBJECTIVE: To determine if second-trimester maternal serum concentrations of unconjugated estriol (E3) and hCG are altered in pregnancies associated with fetal gastroschisis or omphalocele. METHODS: Concentrations of alpha-fetoprotein (AFP), unconjugated E3, and hCG were measured in a case-control study involving 23 cases of gastroschisis, 17 cases of omphalocele, and 200 matched unaffected pregnancies. RESULTS: As reported previously, median AFP levels were significantly higher in pregnancies with gastroschisis and omphalocele compared to unaffected pregnancies (9.42 and 4.18 multiples of the unaffected population median [MoM], respectively). The median hCG values were not significantly different for the two defects (1.10 and 1.13 MoM, respectively). Six of the cases of omphalocele were associated with other anomalies, but exclusion of these cases from the analysis did not alter the conclusions. CONCLUSIONS: Unconjugated E3 and hCG measurements are not useful in screening for, or distinguishing between, open ventral wall defects. Alpha-fetoprotein measurements alone will detect nearly all cases of gastroschisis and most cases of omphalocele.
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Hydrops fetalis and fetal death caused by fetal parvovirus B19 infection have been reported to be associated with elevated maternal serum alpha-fetoprotein (AFP), based on a total of six cases. It has been suggested that the absence of AFP elevation may be reassuring. Maternal serum levels of the Down syndrome screening markers unconjugated oestriol and human chorionic gonadotropin in cases of fetal parvovirus infection have not been previously reported. We report four cases of hydrops fetalis and fetal death caused by fetal parvovirus infection, each with unremarkable second-trimester levels of AFP, unconjugated oestriol, and human chorionic gonadotropin.