Creatine kinase estimation in pure fetal blood samples for the prenatal diagnosis of duchenne muscular dystrophy

This paper compares the results of a survey of plasma creatine kinase (CK) activity measured in fetuses at-risk for Duchenne muscular dystrophy (DMD) with a reliable control series. Only pure fetal blood samples obtained by fetoscopy at between 17–24 weeks gestational age were used. Of the at-risk group 19 male pregnancies, mostly at low risk for DMD, proceeded to term with a normal outcome; there was no significant difference between their fetal plasma CK activities and the control group. Another 21 male pregnancies were terminated. This group included the highest risk mothers and hence was expected to contain a significant proportion of affected fetuses. The fetal plasma CK activity range was overlapping but significantly higher than the control group. No grossly elevated CK value was obtained. We conclude that, on average, DMD fetuses at this gestational age have higher plasma CK activity than controls. The problems of applying this finding to the prenatal diagnosis of DMD are discussed.     

Energy budget of the predatory marine gastropod Polinices duplicatus

Based on direct monitoring of feeding and growth under field conditions and frequent measurements of respiration and energy content in the laboratory, annual energy budgets were derived for Polinices duplicatus feeding on Mya arenaria at Barnstable Harbor, Massachusetts. The gross growth efficiency (P_g/C) of P. duplicatus was high (35%) and varied inversely with snail size. The proportion of ingested energy expended on respiration (R/C) was modest (44%) and varied directly with snail size and inversely with temperature. The energetic efficiencies of P. duplicatus agreed with the few results available for othe predatory molluscs and differed from most results available for herbivorous and detritivorous molluscs.     

An evaluation of the urban stormwater pollutant removal efficiency of catch basin inserts.

In a storm sewer system, the catch basin is the interface between surface runoff and the sewer. Responding to the need to improve the quality of stormwater from urban areas and transportation facilities, and spurred by Phase I and II Stormwater Rules from the U.S. Environmental Protection Agency, several companies market catch basin inserts as best management practices for urban water quality management. However, little data have been collected under controlled tests that indicate the pollutant removal efficiency of these inserts when the inflow is near what can be expected to occur in the field. A stormwater simulator was constructed to test inserts under controlled and replicable conditions. The inserts were tested for removal efficiency of total suspended solids (TSS) and total petroleum hydrocarbons (TPH) at an inflow rate of 757 to 814 L/min, with influent pollutant concentrations of 225 mg/L TSS and 30 mg/L TPH. These conditions are similar to stormwater runoff from small commercial sites in the southeastern United States. Results from the tests indicate that at the test flowrate and pollutant concentration, average TSS removal efficiencies ranged from 11 to 42% and, for TPH, the removal efficiency ranged from 10 to 19%.     

Analysis of colloid and tracer breakthrough curves

We consider the dispersion and elution of colloids and dissolved nonsorbing tracers within saturated heterogeneous porous media. Since flow path geometry in natural systems is often ill-characterized macroscopic (mean) flow rates and dispersion tensors are utilized in order to account for the sub-model scale microscopic fluctuations in media structure (and the consequent hydrodynamic profile). Even for tracer migration and dispersal this issue is far from settled.Here we consider how colloid and tracer migration phenomena can be treated consistently. Theoretical calculations for model flow geometries yield two quantitative predictions for the transport of free (not yet captured) colloids with reference to a non-sorbing dissolved tracer within the same medium: the average migration velocity of the free colloids is higher than that of the tracer; and that the ratio of the equivalent hydrodynamic dispersion rates of colloids and tracer is dependent only upon properties of the colloids and the porous medium, it is independent of pathlengths and fluid flux, once length scales are large enough.The first of these is well known, since even in simple flow paths free colloids must stay more centre stream. The second, if validated suggests how solute and colloid dispersion may be dealt with consistently in macroscopic migration models. This is crucial since dispersion is usually ill-characterized and unaddressed by the experimental literature. In this paper we present evidence based upon an existing Drigg field injection test for the validity of these predictions.We show that starting from experimental data the fitted dispersion rates of both colloids and non-sorbing tracers increase with the measured elution rates (obeying slightly different rules for tracers and colloids); and that the ratio of colloid and nonsorbing tracer elution rates, and the ratio of colloid and nonsorbing tracer dispersion rates may be dependent upon properties of the colloids and the medium (not the flow regime).It is important to realize that even for unretarded species, an earlier peak in the breakthrough curve does not necessarily correspond to a faster mean elution rate, or vice versa. But rather that a colloid may elute faster but disperse less than an equivalent tracer. Hence its peak may be retarded compared to that of the tracer, even assuming no retardation. Hence one must consider a combination of mean elution rate and mean dispersion rate, and not rely on “peak times” to corroborate chromatographic effects. The importance of this lies in the fact that these processes are not independent and yet upscale differently. Thus realistic estimates of effective colloid dispersion rates should be upscaled in a way consistent with that adopted for tracers within the same system.     

Volatile hydrocarbon emissions from a diesel fuel-contaminated soil bioremediation facility

Concerns have been expressed that emissions of volatile hydrocarbons (HCs) from bioremediation facilities containing soils contaminated with petroleum HCs may negatively impact regional air quality or human health. Little information is available regarding the emission of HCs from bioremediation sites, and few field studies have been performed during which the flux of HCs has been directly measured during bioremediation. To aid in answering questions about the impact of bioremediation facilities on the atmospheric environment, a two-part field study was conducted over summer 1996 at a remote landfarm in northern Ontario where diesel fuel-contaminated soil was undergoing bioremediation. Volatile total hydrocarbon (THC) atmospheric flux measurements were successfully taken over 18 days using a flux gradient micrometeorological technique incorporating a THC detector constructed in-house. Peak THC emissions reached 131 microg C/m2/sec shortly after implementation and tilling of the landfarm soil. The influence of soil temperature and tillage on THC emissions was examined. Off-site inhalation exposure was considered with the aid of an areal source model and results from speciated air samples collected on sorbent tubes and analyzed via gas chromatography/mass spectrometry (GCMS) techniques.     

Coral reef habitat mapping: how much detail can remote sensing provide?

The capability of satellite and airborne remote-sensing methods for mapping Caribbean coral reefs is evaluated. Reef habitats were categorised into coarse, intermediate and fine detail, using hierarchical classification of field data (percent cover in 1 m quadrats and seagrass standing-crop). Habitats were defined as assemblages of benthic macro-organisms and substrata and were mapped using the satellite sensors Landsat MSS, Landsat TM, SPOT XS, SPOT Pan and merged Landsat TM/SPOT Pan. Habitats were also mapped using the high-resolution digital airborne sensor, CASI (compact airborne spectrographic imager). To map areas >60 km in any direction with coarse detail, Landsat TM was the most accurate and cost-effective satellite sensor (SPOT XS when <60 km). For maps with intermediate habitat detail, aerial photography (from a comparable study in Anguilla) exhibited similar accuracy to Landsat TM, SPOT XS, SPOT Pan and merged Landsat TM/SPOT Pan. Landsat MSS was consistently the least accurate sensor. Maps from CASI were significantly (p<0.001) more accurate than satellite sensors and aerial photographs. Maps with detailed habitat information (i.e. >9 reef classes) had a maximum accuracy of 37% when based on satellite imagery, but aerial photography and CASI achieved accuracies of 67 and 81%, respectively. Commissioning of new aerial photography does not appear to be a cost-effective option; satellites are cheaper for coarse habitat-mapping, and detailed habitat-mapping can be conducted more accurately and cheaply with CASI. The results will guide practitioners in matching survey objectives to appropriate remote-sensing methods. Received: 11 July 1997 / Accepted: 6 August 1997     

Evidence of in situ diel vertical migration of a red-tide microplankton species in Ría de Vigo (NW Spain)

The migration capacity of red-tide species in the natural environment was studied at a station in the Ría de Vigo (Rías Bajas, NW Spain) over a 24 h period in September 1991. The Ría de Vigo, where red tides are frequent, normally shows a positive estuarine circulation and is subjected to seasonal upwelling and downwelling phenomena. A marked diel pattern was observed for five species that are capable of causing red tides (Ceratium furca, Scrippsiella trochoidea, Dinophysis acuminata, Mesodinium rubrum, and Eutreptiella sp.). Such diel behaviour could be clearly advantageous in a stratified environment where light and nutrients are often in two separate layers. Active movement enables species such as dinoflagellates and some ciliates to exploit high levels of irradiance at the surface during the day and to take up nutrients in deeper layers at night. Patchy distribution of phytoplankton, shear-induced horizontal dispersion and density variations were considered, but none of them accounted for the vertical changes observed. Vertical migration is thought to be one of the mechanisms that could promote blooms in nutrient-depleted surface layers.