Cystic hygroma simulating an encephalocele

An ultrasound examination at 17 weeks gestation on a woman with a family history of spina bifida suggested that the fetus had a closed encephalocele. Amniotic fluid alphafetoprotein, rapidly adhering cells and acetylcholinesterase gel electrophoresis were normal. The pregnancy was terminated and the fetus was found to have a large cystic hygroma. It is suggested that in counselling parents of an infant or fetus with a cystic hygroma and with a normal chromosome constitution, ultrasound examination in future pregnancies is advisable, because of the possibility of autosomal recessive inheritance.     

加拿大地盾湖泊中的沿岸小型甲壳动物(枝角目和桡足亚纲)酸化指示种

在过去两次间隔10年的加拿大地盾湖泊调查中,我们确定了一些沿岸小型甲壳动物的酸性指示种.我们总共发现了90种其丰度在非酸性湖中比在酸性湖中高出几倍的枝角目动物和桡足亚纲动物.在这两次调查中非酸性湖泊的动物群有所变化.1987年的调查中使用了活动捕集器,比在后来的、拉网式的调查中捕到的沿岸生物种类多.这两次调查中均在酸性湖泊中发现了类似的动物群,并找到了几个很好的指示种.例如,Acanthocycops vernalis只存在于pH值小于6的湖泊中.Sinobosmina sp.是常见物种,但只存在于pH值大于4.8的湖泊中.Tropocyclops extensus(近剑水蚤属)、Mesocyclops edax和Sida crystallina(晶莹仙达蚤)比较常见,但只存在于pH值大于5的湖泊中;而Chydorus faviformis(盘肠蚤属)只存在于pH值大于5.9的湖泊中.在两次调查活动中均接受调查的3个湖泊中,这些酸性指示种在从酸化中复原的早期阶段进行的测定中显示出较好的前景.     

Prenatal diagnosis of alpha-1-antitrypsin deficiency by fetal blood sampling

Fetal blood sampling for the diagnosis of alpha-1-antitrypsin deficiency using protein isoelectric focusing was carried out in the period 1980–1985. The results of 25 cases from 18 mothers are reported. All had a previous history of a PiZ child affected by liver disease. The method was found to be technically satisfactory and the fetal results were subsequently confirmed in all 18 cases where follow-up was possible. The fetus was found to be PiZ in nine cases and all these pregnancies were terminated. Of the remaining pregnancies three cases aborted or were delivered prematurely and 13 proceeded to term without complications.     

Examination of fetuses after induced abortion for fetal abnormality—a follow-up study

In the North-Western Region we offer a service to examine fetuses aborted after the diagnosis of fetal abnormalities. Many obstetricians use this service. We examined 343 mid-trimester fetuses over the last 5 years: 215 following an abnormal scan and 128 abnormal amniotic fluid or villus findings. When necessary, investigations were performed. A post-mortem examination was always required. As a result of fetal investigation, the scan diagnosis was modified or refined in 91 cases (42·3 per cent). In three of these cases, no fetal abnormality was found. For the fetuses diagnosed as abnormal by amniocentesis or chorionic villus biopsy, in one (0·8 per cent) the pre-termination diagnosis was not confirmed. The results were similar to those of our previous 5-year study except (a) diagnosis of neural tube defects was rarely based on amniocentesis in the present study (2/62, 3·2 per cent) compared with the previous one (32/103, 31 per cent), and (b) renal abnormalities were more often diagnosed in the pre-termination scan in the present study. We conclude that the examination of aborted mid-trimester fetuses by dysmorphologists continues to improve diagnosis, allowing more accurate genetic counselling for the families.     

UVR sensitivity of Chaoborus larvae

In small temperate lakes, predation by fish generally regulates the species structure and abundance of larval Chaoborus. Yet, Chaoborus abundance may also vary appreciably among lakes with no fish. Many fishless lakes in Sudbury, Ontario, have transparent waters. This raises the possibility that low abundance of Chaoborus in such lakes may be attributable to UVR-induced mortality. To determine whether UVR affects Chaoborus survival, we performed 6 in situ experiments over 2 to 4 day periods at 4 depths in Ruth-Roy Lake (a clear fishless lake with few Chaoborus). Third and fourth instar C. punctipennis were randomly allocated to 3 treatments: quartz (UVR+ PAR), OP3 acrylite (PAR only) and dark controls. Survival under UVR+PAR was significantly reduced in comparison with the other treatments. Survival under PAR only was high, and did not differ from the dark controls. Time to death increased with incubation depth and larval stage. These results suggest that the small Chaoborus population in Ruth-Roy Lake, and perhaps in other fishless, clear lakes may be attributed to UVR-induced mortality.     

Littoral microcrustacean (Cladocera and Copepoda) indicators of acidification in Canadian Shield lakes

We identify littoral microcrustacean indicators of acidification in 2 surveys of Canadian Shield lakes conducted 10 years apart. We found a total of 90 cladoceran and copepod species with richness increasing severalfold from acidic to nonacidic lakes. The fauna of the nonacidic lakes differed between the surveys. The 1987 survey employed activity traps, and caught more littoral taxa than the more recent, net-haul-based survey. Similar faunas were identified in the acidified lakes in both surveys, and several good indicator species were identified. For example, Acanthocycops vernalis was restricted to lakes with pH < 6. Sinobosmina sp. was very common but only in lakes with pH > 4.8. Tropocyclops extensus, Mesocyclops edax, and Sida crystallina were commonly found but only at pH > 5, and Chydorus faviformis only at pH > 5.9. These indicators showed promise in gauging the early stages of recovery from acidification in 3 lakes that were included in both surveys.     

Developing conceptual frameworks for the recovery of aquatic biota from acidification

Surface water acidity is decreasing in large areas of Europe and North America in response to reductions in atmospheric S deposition, but the ecological responses to these water-quality improvements are uncertain. Biota are recovering in some lakes and rivers, as water quality improves, but they are not yet recovering in others. To make sense of these different responses, and to foster effective management of the acid rain problem, we need to understand 2 things: i) the sequence of ecological steps needed for biotic communities to recover; and ii) where and how to intervene in this process should recovery stall. Here our purpose is to develop conceptual frameworks to serve these 2 needs. In the first framework, the primarily ecological one, a decision tree highlights the sequence of processes necessary for ecological recovery, linking them with management tools and responses to bottlenecks in the process. These bottlenecks are inadequate water quality, an inadequate supply of colonists to permit establishment, and community-level impediments to recovery dynamics. A second, more management-oriented framework identifies where we can intervene to overcome these bottlenecks, and what research is needed to build the models to operationalize the framework. Our ability to assess the benefits of S emission reduction would be simplified if we had models to predict the rate and extent of ecological recovery from acidification. To build such models we must identify the ecological steps in the recovery process. The frameworks we present will advance us towards this goal.     

Photodegradation of hydroxylated N-heteroaromatic derivatives in natural-like aquatic environments. A review of kinetic data of pesticide model compounds

In the present review, the results published by our group and others related with the study of the kinetic behavior and, in some cases, the mechanism of the dye-promoted photooxygenation of several hydroxypyridines, hydroxyquinolines and hydroxypyrimidines--some of them with the basic molecular structures of known pesticides, and of a few non-hydroxylated model compounds, are compiled and discussed. The main aim was to examine the experimental conditions that maximize the photodegradation efficiencies of all these compounds, under dye-sensitized photooxidation conditions similar to those frequently found in nature, with a natural dye sensitizer such as riboflavin (vitamin B2), a pigment habitually present in natural waters. The usual mechanism of action of this compound is rather complex, in many cases with the concurrent involvement of the oxidative species singlet molecular oxygen (O2(1Deltag)) and superoxide radical anion. In order to simplify the study of the processes, the results found using the synthetic dye Rose Bengal (RB), a sensitizer that generates O2(1Deltag) with high efficiency, are also discussed. RB and similar O2(1Deltag)-generators could be used for the efficient non-natural photodegradation of related pesticides in aqueous solutions under controlled conditions.