Prenatal diagnostic procedure for leukocyte adhesion deficiency

Leukocyte adhesion deficiency (LAD) is a rare autosomal recessive disorder which leads to recurrent severe infections due to impaired leukocyte functions. The disorder is caused by an absence or deficiency of leukocyte cell adhesion molecules (LeuCAMs) on the leukocyte membranes. The diagnosis is established with monoclonal antibodies against the LeuCAMs. We have carried out a prenatal diagnostic procedure by means of cordocentesis in a mother who was 20 weeks pregnant and had previously given birth to a child with LAD. This previous child had the severe form of LAD with undetectable mRNA for the β chain, the common subunit of the LeuCAMs. We found that the fetal granulocytes expressed the LeuCAMs normally. At birth, the baby was physically normal and showed no signs of impaired leukocyte functions.     

Normal ranges of the activities of ten different enzymes in 100 independent preparations of chorionic villi. Comparison of specimens from induced abortions,biopsies, and cultured cells

In order to obtain a large set of normal control values, the activities of three cytosolic enzymes of purine metabolism and seven lysosomal enzymes were determined in homogenates of chorionic villi derived from induced abortions of normal pregnancies (7th–12th week) in about 100 individual cases. Possible reasons for the rather wide ranges of normal distributions of enzyme activities are discussed. The values are compared: (1) with available data in the literature; (2) with activities determined in decidual homogenates prepared from the same samples; (3) with activities of cells of cultures established and grown from villi in the same samples; and (4) with enzyme activities measured in chorionic biopsies using the same methods. Implications for the prenatal diagnosis of the associated metabolic diseases are considered.     

Increased maternal serum alpha-fetoprotein and human chorionic gonadotropin in compromised pregnancies other than for neural tube defects or Down syndrome

Intrauterine fetal death occurred in four women who were ‘screen-positive’ in a screening programme for neural tube defects (NTDs) and Down syndrome (DS). These women had very high levels of maternal serum alpha-fetoprotein (MSAFP) and maternal serum human chorionic gonadotropin (MShCG). Therefore, we evaluated all ‘screen-positive’ women in whom both of these markers were ⩾ 2.0 multiples of the median. The cases fulfilling these criteria totalled 11, and only one of them had no complications. High concentrations of both MSAFP and MShCG in a number of these cases might have been caused by an increased placental volume, which, in turn, might have been induced by decreased perfusion of the placenta. We conclude that screening programmes wrongly determine a high risk of fetal NTD or DS if the concentrations of both these parameters are very high. Invasive diagnostic procedures should be avoided in these cases, particularly in view of the increased risk of an adverse pregnancy outcome.     

The influence of serum screening on the amniocentesis rate in women of advanced maternal age

We investigated the effect of maternal serum screening on the amniocentesis (AC) rate in women of advanced maternal age. The AC rate after maternal serum screening was compared in two groups of women with a singleton pregnancy, 855 women of 30–35 years and 98 of 36 years and older. In our population, 34·1 per cent of the women of 36 years or older were ‘screen-positive’ for Down syndrome. Only 41·2 per cent of these women chose to undergo AC as opposed to 88·2 per cent in the younger age group. Within the older age group, the tendency to avoid AC increased with increasing age. Maternal serum screening led to a significant decrease in the AC rate in the older women. In this group, a comparison between the ‘a priori’ and the calculated risk might have had more influence on the decision to undergo AC than being screen-positive or screen-negative as such. We conclude that maternal serum screening had a major effect on the AC rate in women of advanced maternal age. This is of importance in a society in which the average maternal age is steadily increasing.     

Introduction of the northern Pacific asteroid Asterias amurensis to Tasmania: reproduction and current distribution

The northern Pacific asteroid Asterias amurensis (Lütken) has been recently introduced to Tasmania and is now well-established in east and southeast Tasmania. This sea star is conspicuous throughout the Derwent River estuary and is particularly abundant in the Hobart port area. Reproduction of two populations of A. amurensis at Sullivans Cove and at Sandy Bay was investigated from August 1993 to October 1994 by gonadal histology and measurement of the gonad index (GI). An intense period of vitellogenic and spermatogenic growth started in April, with the breeding condition reached by June. In 1994, peak GI was recorded at Sullivans Cove in July and at Sandy Bay in August. Although these data indicated that the Sullivans Cove population spawned before the Sandy Bay population, histological examination revealed that major spawning activity occurred in both populations from July onwards. In the early part of the breeding season, gametogenesis proceeded in parallel with spawning, with released gametes being replaced by continual gametogenesis. Maintenance of a higher GI during the early part of the breeding season at Sandy Bay was due to prolonged gametogenic replacement at this site. Spawning continued to October 1994, resulting in a sharp decline in the GI. The cyclic expansion and regression of the genital haemal sinus coincident with germinal proliferation and growth, respectively, support the contention that haemal fluid provides nutrients for gametogenesis. In Tasmania, A. amurensis experiences temperature and photoperiod regimes similar to those experienced by endemic populations of this species in the north Pacific. Comparison of reproduction of A. amurensis in Japan and Tasmania at similar latitudes shows that gametogenesis of the northern and southern populations is 6 mo out of phase. This phase shift provides evidence for photoperiodic regulation of gametogenesis in A. amurensis. The similar trend in sea-temperature regimes associated with the stages of gametogenesis in northern and southern populations suggests that temperature also plays a modulatory role. Based on the periodicity of reproduction and the ontogeny of A. amurensis, the planktotrophic larvae of this species would be expected to be in the plankton for several months from the end of winter through summer. Considering the highly fecund, dispersive life-history of A. amurensis, the southeast Tasmanian populations have considerable potential to serve as a seed source for establishment of new populations of this asteroid elsewhere in Tasmania and in mainland Australia. Received: 18 October 1996 / Accepted: 22 October 1996     

Toxicity of the mosquito control pesticide Scourge to adult and larval grass shrimp (Palaemonetes pugio)

This study investigated the toxicity of various concentrations of technical resmethrin and Scourge on adult and larval Palaemonetes pugio, a common grass shrimp species. Two types of tests were conducted for each of the resmethrin formulations using adult and larval grass shrimp life stages, a 96-h static renewal aqueous test without sediment, and a 24-h static nonrenewal aqueous test with sediment. For resmethrin, the 96-h aqueous LC50 value for adult shrimp was 0.53 microg/L (95% confidence interval (CI): 0.46-0.60 microg/L), and for larval shrimp was 0.35 microg/L (95% CI: 0.28-0.42 microg/L). In the presence of sediment, technical resmethrin produced a 24-h LC50 value for adult shrimp of 5.44 microg/L (95% CI: 4.52-6.55 microg/L), and for larval shrimp of 2.15 microg/L (95% CI: 1.35-3.43 microg/L). For Scourge, the 96-h aqueous LC50 for adult shrimp was 2.08 microg/L (95% CI: 1.70-2.54 microg/L), and for larval shrimp was 0.36 microg/L (95% CI: 0.24-0.55 microg/L). The 24-h sediment test yielded an LC50 value of 16.12 microg/L (95% CI: 14.79-17.57 microg/L) for adult shrimp, and 14.16 microg/L (95% CI: 12.21-16.43 microg/L) for larvae. Adjusted LC50 values to reflect the 18% resmethrin concentration in Scourge are 0.37 microg/L (adult), 0.07 microg/L (larvae) for the 96-h aqueous test, and 2.90 microg/L (adult), 2.6 microg/L (larvae) for the 24-h sediment test. Larval grass shrimp were more sensitive to technical resmethrin and Scourge than the adult life stage. The results also demonstrate that synergized resmethrin is more toxic to P. pugio than the nonsynergized form, and that the presence of sediment decreases the toxicity of both resmethrin and Scourge.     

A rule-based screening environmental risk assessment tool derived from EUSES

Within the context and scope of the forthcoming European Union chemical regulations (REACH), there is a need to be able to prioritise the chemicals for evaluation. Therefore, a simple, pragmatic and adequately conservative approach for the identification of substances of very low or no immediate concern at an early stage is presented. The fundamental principles and basic concepts are derived from the EU Technical Guidance Document and EUSES, and are translated into an easy-to-use rule-based system. For this development, the effect on risk characterisation ratios (RCRs) of the key environmental parameters in EUSES was quantified (taking into account several standardised chemical release scenarios). Using statistical analysis, ranges were identified for each key parameter, within which the end result of the assessment was not significantly affected. This information was then translated into a lookup table from which environmental risk characterisation ratios can be directly read as a function of a few parameters.