Screening maternal serum alpha-fetoprotein levels and human parvovirus antibodies

The association between gestational infection with human parvovirus (B19) and fetal loss has increased interest in this virus and demand for diagnostic testing. However, serological assays for B19 are not yet widely available. Maternal serum alpha-fetoprotein (MSAFP) testing is commonly used during the second trimester to screen for various fetal defects. We attempted to determine whether an elevated level of MSAFP would be an appropriate indication for B19-specific tests. Over a 26-month period, MSAFP tests were performed at Michigan State University for 21 392 women. Sera remaining after that testing were stored frozen. Of these, 22 case samples—from women with MSAFP levels greater than 3·0 multiples of the median (MOM) and pregnancies that ended in fetal loss—and 44 matched control samples—from women with MSAFP levels greater than 0·4 and less than 2·2 MOM and live births at term—were tested for B19 antibodies. None of the 66 samples was IgM positive, while 33 (50 per cent) were IgG positive. The presence of IgG was not significantly associated with case or control status (matched odds ratio=0·77, 95 per cent confidence interval 0·28–2·11). These findings are consistent with other studies indicating prior infection in approximately half of adults and suggest that elevated screening MSAFP levels, in the absence of other evidence of B19 infection, should not prompt B19-specific testing.     

Monosomy 8q: Prenatal diagnosis and autopsy findings

The autopsy findings of a fetus with deletion of the long arm of chromosome 8 are described. Many of the features are similar to those of the tricho-rhino-phalangeal syndromes, types I and II, which are associated with deletions on chromosome 8q24. Other findings in this case, such as total absence of the corpus callosum and intestinal malrotation, have not been described in these syndromes. Genes involved in the development of the latter malformations may reside in adjacent regions on the long arm of chromosome 8. An elevated serum level of beta human chorionic gonadotropin (βhCG) was found during pregnancy. This aberration should be included with other chromosomal disorders which may be detected by this test.     

Apparent non-mosaic trisomy 16 in chorionic villi: Diagnostic dilemma or clinically significant finding?

A case is presented in which apparent non-mosaic trisomy 16 was found in chorionic villi (direct and culture) obtained from a patient undergoing first-trimester prenatal diagnosis. The fetal karyotype subsequently was determined to be 46,XX by follow-up amniocentesis. Serial ultrasonographic examinations revealed placental sonolucencies and intrauterine growth retardation. At 37 weeks, a small-for-gestational-age female was delivered by Caesarean section for fetal distress. Postnatal cytogenetic studies revealed a normal female karyotype in cord blood and mosaic trisomy 16 in plaental tissues. These findings suggest that in cases where aneuploidy is confined to placental tissues, it may have biological significance, as evidenced by the apparent placental dysfunction and poor fetal growth in this case.     

Maternal serum alpha-fetoprotein levels and fetal outcome in early second-trimester oligohydramnios

Early second-trimester oligohydramnios was associated with normal maternal serum alpha-fetoprotein (MSAFP) levels in nine out of 26 cases (35 per cent). Congenital malformations of the fetal urinary tract resulting in fetal anuria were present in nine cases; in seven of them, normal MSAFP levels were measured. In contrast, normal MSAFP levels were established in only 2 out of the 17 cases without fetal malformations. These data suggest that fetal urine is the major source of elevated AFP in the maternal compartment in early second-trimester oligohydramnios. This is further supported by the lack of any relationship between concentrations of MSAFP non-reactive with Concanavalin A, originating mainly from the yolk sacderived amniotic fluid AFP pool, and the presence of fetal diuresis. Three out of 26 women had experienced early second-trimester oligohydramnios in a previous pregnancy, suggesting the existence of a recurrence risk for this condition.     

Adverse perinatal outcome in patients screen-positive for neural tube defects and fetal down syndrome

An association between various abnormal mid-trimester maternal serum analyte values and adverse perinatal outcome has been reported. From an original sample of 14 857 women, we observed five women who were ‘screen-positive’ for both neural tube defects [maternal serum alpha-fetoprotein (MSAFP) ≥2·5 multiples of the median] and Down syndrome [risk ≥1/274 using MSAFP, maternal serum unconjugated oestriol (MSuE3), maternal serum human chorionic gonadotropin (MShCG), and maternal age]. The four patients who elected to undergo amniocentesis all demonstrated both normal karyotype and normal amniotic fluid AFP levels. All five cases were associated with intrauterine growth retardation (IUGR) and abnormal pregnancy outcomes. Two cases exhibiting severe IUGR on ultrasound examination were terminated at 19·1 and 21·2 weeks, respectively; the former also exhibited fetal calcifications and positive maternal serology for toxoplasmosis. In another case, fetal demise occurred at 36 weeks' gestation in a patient who had been treated for syphilis in the second trimester. Neither infection was confirmed in fetal tissue studies. Though resulting in live births, the remaining two cases required operative deliveries; emergency Caesarean sections for fetal distress were performed at 38 and 32 weeks, respectively, the latter case being associated with severe pre-eclampsia. We conclude that elevated mid-trimester MSAFP levels concurrent with maternal serum analyte values associated with increased risk for fetal Down syndrome may presage a poor perinatal outcome, particularly IUGR and possibly congenital infection.     

Lysosomal membrane stability,phagocytosis and tolerance to emersion in the mussel Perna viridis (Bivalvia: Mytilidae) following exposure to acute,sublethal, copper

The mytilid mussel Perna viridis is distributed throughout the Indo-Pacific region and is potentially a suitable candidate for biological effects (biomarker) monitoring in the subtropics. A suite of cytological and physiological responses to acute (48-72 h) copper exposures of 50-200 microgl(-1) were assessed in order to determine the suitability of P. viridis for marine pollution monitoring. Copper elicited significant destabilisation of the haemocyte lysosomal membranes and also impaired phagocytosis. Survival during emersion following exposure to copper was not related to the experimental copper exposures suggesting that higher metal concentrations may be required to interfere with anaerobic enzymes responsible for suppression of metabolism. Based on this preliminary study, cytological biomarkers evaluated in the haemocytes extracted from P. viridis should prove an effective non-destructive means of assessing metal pollution throughout the mussels subtropical range.     

Local likelihood disease clustering: development and evaluation

This paper illustrates a method based on local likelihood (LL) for detecting disease clusters. The approach is based on estimating a lasso distance for each region: within which regions are considered to be clustered. An important advantage in implementing this approach is that it does not require any special Monte Carlo Markov Chain (MCMC) algorithm, e.g., reversible jump MCMC, which is essential in hidden Markov model approach. Another advantage is that extending the model to incorporate covariates is straightforward. We illustrate three ways of doing this by using Eastern Germany lip cancer data. By using simulated data, we have made a comparison with the BYM model [Besag et al. (1991) Annals of the Institute of Statistical Mathematics, 43, 1–59] and the mixture model [Lawson and Clark (2002) Disease Mapping and Risk Assessment for Public Health, Chapman and Hall]. We also did a limited examination of the ability of the LL model to recover true relative risk under different priors for lasso parameter. In order to check the edge effects, which has been overlooked in many spatial clustering models for disease mapping but deserves special attention as it lacks observable neighbors, we have adapted here a simple approach to observe the changes in relative risks when the edge regions are omitted. An erratum to this article is available at .     

Measuring ammonia emissions from land applied manure: an intercomparison of commonly used samplers and techniques

A number of techniques have been developed to quantify ammonia (NH(3)) emissions following land application of manure or fertiliser. In this study, coefficients of variation were determined for three commonly used field techniques (mass balance integrated horizontal flux, wind tunnels and the equilibrium concentration technique) for measuring emissions from a range of manure types. Coefficients of variation (CV) for absorption flasks, passive flux samplers and passive diffusion samplers were 21, 10 and 14%, respectively. In comparative measurements, concentrations measured using passive flux samplers and absorption flasks did not differ significantly, but those measured using passive diffusion samplers were on average 1.8 times greater. The mass balance technique and wind tunnels gave broadly similar results in two out of four field tests. Overexposure of passive diffusion samplers for some sampling periods meant that estimation of cumulative NH(3) emission using the equilibrium concentration technique in the field tests could not be made. For cumulative NH(3) emissions, CVs were in the range of 23-52, 46-74 and 21-39% for the mass balance, wind tunnel and equilibrium concentration techniques, respectively. Lower CVs were associated with measurements following slurry compared with solid manure applications. Our conclusions from this study are that for the measurement of absolute emissions the mass balance technique is to be preferred, and for small-plot comparative measurements the wind tunnel system is preferred to the equilibrium concentration technique.