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Biomedical subjects

D B Peakall

Publications and source records attributed to D B Peakall.

At least 19 recordsLinked to original sources
PubMed1992

Arctic marine ecosystem contamination.

The current state of knowledge of levels, spatial and temporal trends of contaminants in the Arctic marine ecosystem varies greatly among pollutants and among environmental compartments. Levels of polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and some heavy metals such as mercury and lead, in Arctic marine mammals and fish are relatively well documented because of the need for comparisons with biota in more polluted environments and interest in the contamination of native diets. Levels of heavy metals, alkanes, polyaromatic hydrocarbons (PAH) and OCs in the Arctic Ocean are comparable to uncontaminated ocean waters in the mid-latitudes. But concentrations of alpha- and gamma-hexachlorocyclohexane (HCHs) are higher in northern waters far removed from local sources, possibly because lower water temperature reduces transfer to the atmosphere. Bioaccumulation of OCs and heavy metals in Arctic marine food chains begins with epontic ice algae or phytoplankton in surface waters. Polychlorinated camphenes (PCC), PCBs, DDT- and chlordane-related compounds are the major OCs in marine fish, mammals and seabirds. Mean concentrations of most PCBs and OC pesticides in ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic are quite similar indicating a uniform geographic distribution of contamination, although alpha-HCH showed a distinct latitudinal gradient in bears due to higher levels in zones influenced by continental runoff. Ringed seals from Spitzbergen have higher levels of PCBs, total DDT and polychlorinated dioxins/furans (PCDD/PCDFs). In contrast to other OCs, PCDD/PCDFs in Canadian Arctic ringed seals and polar bears were higher in the east/central Arctic than at more southerly locations. Remarkably high cadmium levels are found in kidney and liver of narwhal (Monodons monoceros) from western Baffin Bay (mean of 63.5 micrograms g-1) and western Greenland waters (median of 39.5 micrograms g-1). Mercury concentrations in muscle of ringed seal and cetaceans frequently exceed 0.5 microgram g-1 especially in older animals. Cadmium concentrations in polar bear liver increased from west to east, while mercury levels were higher in ringed seals from the western Canadian Arctic, which suggests that natural sources of these metals predominate. Studies of temporal trends in OCs in ringed seals and seabirds in the Canadian Arctic indicate PCB and DDT levels declined significantly from the early 1970s to the 1980s. There is a lack of temporal trend data for other OC pesticides as well as for heavy metals and hydrocarbons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Mixed-function oxidase activity in seabirds and its relationship to oil pollution.

1. The hepatic activity of epoxide hydrolase, aldrin epoxidase, aminopyrine N-demethylase, 7-ethoxyresorufin O-deethylase, benzo(a)pyrene 3-hydroxylase and UDP glucuronyl transferase was determined in adult herring gulls (Larus argentatus) at various stages of the breeding season. 2. MFO activity was measured for adult Leach's storm-petrels (Oceanodroma leucorhoa), guillemot (Uria aalge) and Atlantic puffins (Fratercula arctica). For most assays the values were highest for the puffin. 3. MFO activity in both nestling and adult Atlantic puffins was determined. The degree of induction caused by a single internal dose of Prudhoe Bay crude oil in adult puffins and that caused by multiple internal doses in nestling puffins was measured.

Animals↗
PubMed1987

Toxicological investigations of pollutant-related effects in Great Lakes gulls.

Reproductive failure of a number of fish-eating birds was observed on the Great Lakes in the mid-1960s to mid-1970s. The herring gull (Larus argentatus) has been used as the primary monitoring species. The low hatching success observed in this species on Lake Ontario in the mid-1970s was due to loss of eggs and failure of eggs to hatch. Egg exchange experiments demonstrated that this was due both to the incubation behavior of adults and to direct embryotoxic effects. Decrease of nest attentiveness was demonstrated using telemetered eggs, but attempts to reproduce the embryonic effects by injection of pollutant mixtures into eggs were not successful. Reproductive success improved rapidly during the late 1970s and was normal by the end of the decade. Recent studies have focused on cytogenetic and biochemical changes and detailed analytical chemistry of residues. No changes in the rate of sister chromatid exchange over values determined in coastal colonies were observed. Elevation of hepatic aryl hydrocarbon hydroxylase activity, levels of highly carboxylated porphyrins, and changes of thyroid function have been found. The geographic pattern of these changes indicates that they are caused by xenobiotics, but it has not been possible to relate the changes to a specific chemical.

Animals↗
PubMed1985

Blood chemistry changes in food-deprived herring gulls.

Blood chemistry changes caused by food-stress was measured in fledgling herring gulls (Larus argentatus). Increases of corticosterone, T3, free fatty acids, glucose, cholesterol and alpha-amino n-butyric acid were observed. Significant decreases were found in the concentrations of 14 of the 26 free amino acids studied.

Amino Acids↗
PubMed1979

Effect of toxaphene on pyruvic and lactic acid levels in the rat.

Rats were given a single dose of toxaphene (120 mg/kg equilavent to 1/2 LD50) and sacrificed at 1, 5, and 15 days. No alterations of levels of pyruvic or lactic acid in blood plasma were observed. In a second experiment, rats were given 2.4 mg/kg daily and sacrificed at 1, 3, and 6 months, and again no alterations of pyruvic or lactic acid levels were found. It is concluded that observed alterations of the activity of lactic acid dehydrogenase induced by toxaphene do not give rise to physiological changes in unstressed rats.

Animals↗
PubMed1979

Shell thinning and residues of organochlorines and mercury in seabird eggs, Eastern Canada, 1970-76.

Organochlorine and mercury concentrations are reported for 252 eggs of Leach's storm-petrel (Oceanodroma leucorhoa), double-crested cormorant (Phalarocorax auritus), common eider (Somateria mollissima), common tern (Sterna hirundo), razorbill (Alca torda), common murre (Uria aalge) black guillemot (Cepphus grylle), and Atlantic puffin (Fratercula arctica) from the Bay of Fundy, the Gulf of St. Lawrence, and the open Atlantic shore of Canada during 1970-76. Concentrations of all organochlorines except DDE and polychlorinated biphenyls (PCBs) were low. DDE, PCBs, and mercury residues were highest in cormorant and petrel, intermediated in alcids, and lowest in eider and tern. Temporal and spatial aspects of contamination patterns are discussed. Authors conclude that only in cormorants were DDE residues high enough to cause, through eggshell thinning, local population declines.

Animals↗
PubMed1978

Ingestion of crude oil: sublethal effects in herring gull chicks.

A single small oral dose of Kuwait or South Louisiana crude oil caused cessation of growth, osmoregulatory impairment, and hypertrophy of hepatic, adrenal, and nasal gland tissue in herring gull chicks living in a simulated marine environment. These findings suggest that ingesting crude oil causes multiple sublethal effects that might impair a bird's ability to survive at sea.

Adenosine Triphosphatases↗
PubMed1978

DDT residues in rainwater in New Brunswick and estimate of aerial transport of DDT into the Gulf of St. Lawrence, 1967-68.

Residues of DDT were detected in 76 of 101 samples of rainwater collected during spring and summer at several sites in the Province of New Brunswick in 1967 and 1968, and at one site in the Magdalen Islands, Quebec, in 1968. The dominant residue was p,p'-DDT. Levels of DDT and metabolites combined ranged from less than 0.01 to 1.33 microgram/kg. Levels of DDT and metabolites in the pollen of four species of forest trees in New Brunswick ranged from 0.544 to 1.01 mg/kg; such contaminated pollen possibly contributed to residues in rainwater. Residue data for rainwater from two sites were used to estimate the amount of DDT aerially transported into the Gulf of St. Lawrence during July to October 1968.

Chromatography, Gas↗
PubMed1976

DDE feeding and plasma osmoregulation in ducks, guillemots, and puffins.

To assess the possibility that organochlorine pesticide disruption of osmoregulation is responsible for recent large kills of young seabirds, we have studied the effects of DDE feeding (10-250 ppm) on plasma osmoregulation and nasal gland function in the following species: mallared and white Pekin ducks (both Anas platyrhynchos), black guillemot (Cepphus grylle), and common (Fratercula arctica). Other investigators have recently reported that dietary DDE (10-1,000 ppm) inhibits nasal gland secretion in freshwater-maintained mallards; our initial experiments with white Pekins showed no such inhibition during either freshwater or seawater maintainance. Moreover, DDE had minimal effects on plasma electrolyte levels and total nasal gland Na-K-ATPase activities in all species studied. Liver DDE levels in experimental ducks and guillemots were comparable to those reported for seabirds found dead after kills; levels in starved experimental puffins were much higher. Thus DDE at environmental levels does not affect osmoregulation or nasal gland Na-K-ATPase either in ducks or in two species of oceanic birds.

Adenosine Triphosphatases↗
PubMed1976

Effects of toxaphene on hepatic enzyme induction and circulating steroid levels in the rat.

Rats were given a single dose of toxaphene (120 mg/kg, equivalent to 1/2 LD50) and sacrificed at 1, 5, and 15 days. Liver weight and hepatic microsomal enzyme activity were increased at day 5 and 15. The level of plasma testosterone was significantly decreased at day 15. In a second experiment rats were given 2.4 mg/kg daily and sacrificed at 1, 3 and 6 months. Liver weight and microsomal enzyme activity were significantly increased over controls; enzyme activity was, however, decreasing by the end of the experiment. Plasma testosterone levels were not affected. It is concluded that enhanced hepatic enzyme induction causes only a transient drop in circulating testosterone levels followed by a return to normal values.

Animals↗
PubMed1976

Premature parturition in the California sea lion.

Twenty percent of the California sea lion pups born on San Miguel Island die due to premature parturition. Specimens collected from premature-partus animals resulted in recovery of a virus, San Miguel Sea Lion Virus, indistinguishable from Vesicular Exanthema of Swine Virus, and Leptospira pomona from some of the premature cows and pups. The age range of 10 females delivering healthy pups in June was 10-14 years. With one exception, the ages in 10 aborting females was 6-8 years. The p,p'-DDE levels of the premature parturient cows' blubber and liver were 7.6 and 4.8 times greater, respectively, than corresponding tissue concentrations in the full-term animals. Polychlorinated biphenyls residues were 4.4 and 3.8 times greater in aborting animals' blubber and liver than in the same tissues of full-term sea lions. Premature-partus females had tissue imbalances of mercury, selenium, cadmium and bromine. Pathology, parasitology, serum enzyme and hormone results are also presented. These data suggest an interrelationship of disease agents and environmental contaminants as the cause of premature parturition.

Abortion, Veterinary↗