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L Burridge

Publications and source records attributed to L Burridge.

6 recordsLinked to original sources
PubMed2004

Effects of water-borne 4-nonylphenol and 17beta-estradiol exposures during parr-smolt transformation on growth and plasma IGF-I of Atlantic salmon (Salmo salar L.).

4-Nonylphenol (4-NP) is an endocrine disrupting substance (EDS) capable of mimicking the action of 17beta-estradiol (E2). It has been hypothesized that 4-NP in a pesticide formulation is linked to historical declines in Canadian Atlantic salmon (Salmo salar L.) populations, with effects being related to exposure during parr-smolt transformation (PST). To test this hypothesis, Atlantic salmon smolts were exposed to pulse-doses of water-borne 4-NP (20 ug/l), sustained doses of water-borne E2 (100 ng/l) (positive control), or ethanol vehicle (negative control) in mid-May during the final stages of PST. Individually tagged smolts were then sampled at three times (June, July and October) to monitor subsequent growth in sea water and plasma insulin-like growth factor I (IGF-I) concentrations. Smolt weights and plasma IGF-I concentrations were both affected by E2 and 4-NP. The effects of E2 and 4-NP on mean smolt weights were most prominent in July and October [E2 (*98.1 +/- 2.8, *242.3 +/- 10.6 g), 4-NP (*102.1 +/- 3.1, 255.7 +/- 9.5 g), controls (112.5 +/- 2.8, 282.3 +/- 8.8 g)] (P < 0.05), while their effects on mean plasma IGF-I concentrations were most prominent in June and October [E2 (15.0 +/- 1.9, 28.4 +/- 1.8 ng/ml), 4-NP (*14.8 +/- 1.9, *21.6 +/- 1.7 ng/ml), controls (20.0 +/- 1.1, 31.1 +/- 2.0 ng/ml)] (P < 0.05). Additionally, results suggest that the mechanisms of action of E2 and 4-NP involve disruption in the GH/IGF-I axis, and that they may be different from each other. The effects of E2 and 4-NP on growth and plasma IGF-I concentrations observed in this study are ecologically significant because they evoke concerns for successful growth and survival of wild salmon smolts exposed to low levels of estrogenic substances that may occur from current discharges into rivers supporting sea-run salmon stocks.

Animals↗
PubMed2002

Aquaculture-related trace metals in sediments and lobsters and relevance to environmental monitoring program ratings for near-field effects.

The study was undertaken to assess the marine environmental effects from feed and waste associated with aquaculture activities. Metal compositions of sediment, lobster, and feed were used to evaluate the extent of detectable effects at 0 m (under the cage) and 50 m distance. Sediments that were collected under the cages and were characterised as hypoxic or anoxic, showed elevated levels of Cu, Zn, organic carbon, and % <63 microm particles, and low Mn and Fe. At 50 m there was a major reduction in waste chemical impact. Using lobster, a bioindicator species, as a tool for detecting near-field impacts, showed accumulations of high Cu associated with active aquaculture sites. Chemical compositions and metal ratios normalised with organic carbon, were used to assess the sediment conditions associated with environmental monitoring program ratings (EMP--normal, hypoxic, and anoxic). Principal component analysis (PCA) was used to explore chemical data at all sites for differentiating normal, hypoxic and anoxic sediment conditions. Selected variables (Cu, Zn, Fe, Mn, organic carbon, and particles <63 microm) were sufficient for the PCA approach with >90% explainable variance of first two components. The groupings based on PCA and cluster analysis were similar to EMP classifications with some exceptions of mis-identification by EMP. The sediment chemistry components were valid indicators for evaluating marine environmental conditions and for assessing aquaculture operating sites. The developed techniques, using chemical variables in combination with EMP and the statistical approach should be useful to predict the effects of aquaculture practices and the suitability of aquaculture operations.

Animal Feed↗
PubMed1998

Distinct but overlapping expression patterns of two vertebrate slit homologs implies functional roles in CNS development and organogenesis.

The Drosophila slit gene (sli) encodes a secreted leucine-rich repeat-containing protein (slit) expressed by the midline glial cells and required for normal neural development. A putative human sli homolog, SLIT1, has previously been identified by EST database scanning. We have isolated a second human sli homolog, SLIT2, and its murine homolog Slit2. Both SLIT1 and SLIT2 proteins show approximately 40% amino acid identity to slit and 60% identity to each other. In mice, both genes are expressed during CNS development in the floor plate, roof plate and developing motor neurons. As floor plate represents the vertebrate equivalent to the midline glial cells, we predict a conservation of function for these vertebrate homologs. Each gene shows additional but distinct sites of expression outside the CNS suggesting a variety of functions for these proteins.

Amino Acid Sequence↗
PubMed1993

Challenging the traditional view of preoperative visiting.

Anxiety is a product of helplessness. Admission to hospital precipitates this by disturbing patients' integrity with their life-context. Anxiety is relative to the patient's sense of control, yet preoperative visiting which is meant to be caring may be perceived by the surgical patient as being controlled. The visit is influenced by personalized contact, the structure of the visit and the philosophy behind the preoperative visiting programme. The building of a quality relationship lays a foundation for quality caring, and challenges the visiting nurse to be less directive and more reciprocal, responding appropriately as the patient steers the course of the visit.

Anxiety↗