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M M Gagnon

Publications and source records attributed to M M Gagnon.

15 recordsLinked to original sources
PubMed2005

Alterations of metabolic enzymes in Australian bass, Macquaria novemaculeata, after exposure to petroleum hydrocarbons.

Australian bass Macquaria novemaculeata were exposed to the water-accommodated fraction of Bass Strait crude oil, dispersed crude oil, or burnt crude oil to assess sublethal effects of oil spill remediation techniques on fish. Fish were exposed to these treatments for 16 days either through the water column or by way of a pre-exposed diet of amphipod Allorchestes compressa. Fish gills, liver, and white muscle were sampled and cytochrome C oxidase (CCO) and lactate dehydrogenase (LDH) activities quantified. In all treatments containing fish exposed by way of the water column, aerobic activity increased in the gills, whereas a decrease of this enzymic activity was observed in the liver and white muscle. Exposures by way of the food pathway indicated similar trends. Anaerobic (LDH) activity increased in the gills, liver, and white muscle after waterborne exposures. Stimulation in anaerobic activity also occurred in the liver and white muscle of fish after exposure to contaminated food. CCO activity in the gills was the most sensitive biomarker when monitoring waterborne exposures to petroleum hydrocarbons. In the gills, the dispersed oil treatment resulted in the most pronounced biological response, suggesting that in the short term the use of dispersants on an oil slick might cause the most perturbations to fish metabolism.

Animals↗
PubMed2001

Pink snapper (Pagrus auratus) as a bioindicator of aquatic. Environmental health in Western Australia.

Pink snapper (Pagrus auratus), an endemic Western Australian fish species, was tested for its potential as a bioindicator of aquatic environmental health. Mixed function oxygenase (MFO) induction (as a biomarker of exposure), and sorbitol dehydrogenase (SDH) activity (as a biomarker of liver damage) were of special interest to the study as these biochemical tools have not been validated for any Western Australian fish species. Juvenile pink snapper were injected intraperitoneally (i.p.) with 0, 10, 100, 500, and 1000 micrograms PCB-126 per kilogram. Fish were sacrificed 10 days postinjection, and livers and blood samples were collected for MFO and SDH analysis, respectively. Doses of 10 and 100 micrograms PCB-126 per kilogram caused the highest MFO induction, while doses of 0 and 1000 micrograms PCB-126 per kilogram did not result in higher MFO activity relative to carrier-injected control fish. SDH activities were not significantly different among treatments indicating that hepatocellular damage was not responsible for the reduced MFO activity at the highest dose. The result of the study demonstrates that pink snapper may potentially be used as a bioindicator species in Western Australia when MFO is used as a biomarker.

Animals↗
PubMed2001

Metabolic responses of fish following exposure to two different oil spill remediation techniques.

To assess the impacts of two oil spill remediation techniques on fish metabolism, change in aerobic and anaerobic enzyme activities in juvenile Australian Bass, Macquaria novemaculeata, was examined. Changes in cytochrome C oxidase (CCO) and lactate dehydrogenase (LDH) activities were investigated following exposure to the crude oil water accommodated fraction (WAF) and chemically dispersed crude oil WAF. There was a significant stimulation in CCO activity in the gills and livers of fish exposed to the WAF of Bass Strait crude oil and chemically dispersed crude oil, compared to the control treatment. In addition, LDH activity was significantly stimulated in the liver of fish exposed to dispersed crude oil WAF, compared to the crude oil WAF. Fish exposed to the dispersed crude oil WAF treatment had significantly higher oxygen consumption, as measured by oxygen depletion in a sealed chamber, than fish exposed to the crude oil WAF and control treatments.

Animals↗
PubMed2001

The effect of different oil spill remediation techniques on petroleum hydrocarbon elimination in Australian bass (Macquaria novemaculeata).

Petroleum hydrocarbons were investigated in juvenile Australian bass, Macquaria novemaculeata, following exposure to the water accommodated fraction (WAF) of Bass Strait crude oil, chemically dispersed crude oil, and burnt crude oil. Each treatment was administered for 16 days either through the water column or through the diet (amphipod, Allorchestes compressa). Polycyclic aromatic hydrocarbon (PAH) elimination was determined by measuring biliary benzo(a)pyrene (B(a)P) and naphthalene-type metabolites. Biliary PAH-type metabolite concentrations varied with the type of oil spill remediation technique, route of exposure (food versus water), and exposure concentration. Fish exposed to chemically dispersed crude oil via the water exhibited the highest PAH-type biliary metabolite concentrations, relative to fish exposed to other treatments. In fish exposed via the diet, the highest concentration of both types of biliary metabolites also appeared in the dispersed oil-exposed individuals. The results suggest that chemically dispersing oil may have the greatest effect on bioavailability of hydrocarbons, both through waterborne and food chain exposures.

Animals↗
PubMed2000

EROD induction and biliary metabolite excretion following exposure to the water accommodated fraction of crude oil and to chemically dispersed crude oil.

Immature Atlantic salmon (Salmo salar) were exposed to water accommodated fraction (WAF) of Bass Strait crude oil or to Corexit 9527-dispersed crude oil for 6 days, followed by a depuration period of 29 days. Serum sorbitol dehydrogenase (SDH) levels, indicator of liver damages, remained low during the experiment. Hepatic EROD activity was induced within 2 days following the onset of the exposure in both treatments, and persisted for 2-4 and 4-6 days after transfer to clean sea water in the WAF and dispersed oil treatment, respectively. Naphthalene-type metabolites, determined by fixed-wavelength fluorescence detection, appeared in the bile of the fish with 2 days' delay compared to EROD induction. In both treatments, EROD activity induction and levels of naphthalene-type metabolites in the bile were significantly related. The biliary levels of naphthalene-type metabolites were over 15 times higher in fish exposed to dispersed crude oil relative to fish exposed to the WAF of Bass Strait crude oil. BaP-type metabolites appeared only in the bile of the fish exposed to the WAF, possibly due to BaP-type compounds remaining associated with the dispersant in the water column or to an inhibition of Phase II detoxification enzymes by the dispersant. Bile metabolites as determined by fixed-wavelength fluorescence and EROD induction appear to be sensitive and complementary biomarkers of exposure to PAH.

Animals↗
PubMed2000

Autonomic and neurohumoral control of postprandial blood pressure in healthy aging.

BACKGROUND: Postprandial hypotension (PPH) is a common and morbid problem in elderly people that is associated with an impaired vascular response to meal digestion. Healthy aging in the absence of blood pressure elevation is associated with autonomic and neurohumoral changes that may influence the vascular response to meal ingestion. However, it is not known whether these age-related changes are associated with the development of PPH. METHODS: We measured hemodynamic (blood pressure, heart rate, and forearm vascular resistance), autonomic (power spectral analysis of heart rate and blood pressure variability), and neurohumoral (plasma norepinephrine, renin, aldosterone, and endothelin) responses to a mixed 425 kilocalorie (kcal) meal in 89 rigorously screened healthy subjects aged 20-39, 40-59, and 60-83 years. RESULTS: After the meal, supine mean arterial blood pressure fell significantly only in the middle-aged group by 5.4 +/- 7.9 mm Hg at 30 minutes (p = .02). Forearm vascular resistance fell after the meal in all age groups ( p = .0001). Older groups had higher plasma norepinephrine (p = .02), lower heart rate (p = .03), lower cardiovagal activity (p = .0001), and lower sympathetic vasomotor (p = .000) activity, but there was no difference in the response of these variables to a meal. CONCLUSION: Healthy aging, in the absence of blood pressure elevation, alters the level of autonomic activity without further impairing the ability to maintain blood pressure during meal digestion. Hemodynamic, autonomic, and neurohumoral responses to meal ingestion remain unchanged in very healthy, normotensive elderly adults.

Adult↗
PubMed1999

Effects of postprandial walking exercise on meal-related hypotension in frail elderly patients.

The purpose of this study was to assess the hemodynamic effects of a postmeal walk in frail elderly patients with postprandial hypotension. We demonstrated that frail elderly patients with postprandial hypotension are able to increase their blood pressure and heart rate in response to a postmeal walking exercise, but this effect is limited to the exercise period only and is not sustained during subsequent rest.

Aged↗
PubMed1999

Metabolic enzyme activities in fish gills as biomarkers of exposure to petroleum hydrocarbons.

Metabolic effects of low-level exposure of Atlantic salmon (Salmo salar) to the water accommodated fraction (WAF) of crude oil and to dispersed crude oil were studied. Aerobic enzymes citrate synthase and cytochrome C oxidase, and anaerobic enzyme lactate dehydrogenase were measured in gills during a 4-day exposure to low concentrations of dispersed Bass Strait crude oil and WAF, and during the following 8 days of depuration in clean seawater. Relative to pre-exposure levels, citrate synthase and lactate dehydrogenase exhibited a significant inhibition of activity during exposure to the WAF of crude oil, and to dispersed crude oil, while activity of cytochrome C oxidase remained unchanged. Citrate synthase activities returned to preexposure levels after 4 days following termination of exposure for the WAF-exposed fish, and after 2 days for the dispersed-oil-exposed fish. After the termination of exposure to both treatments, lactate dehydrogenase activity remained low relative to levels measured prior to exposure, which indicated that the activity of this enzyme may be a sensitive medium to long-term biomarker of exposure to petroleum-contaminated water bodies.

Animals↗
PubMed1999

Persistent hyperplastic primary vitreous with retinal tumor in tuberous sclerosis: report of a case including tumoral immunohistochemistry and cytogenetic analyses.

OBJECTIVE: The authors describe an ocular lesion combining the characteristics of persistent hyperplastic primary vitreous (PHPV) and a retinal tumor in an infant with tuberous sclerosis complex (TSC). STUDY DESIGN: Case report. METHODS: Immunohistochemistry and cytogenetic studies were performed on TSC cells from an intraocular tumor in a 6-week-old infant. RESULTS: Histopathologic examination showed a thick fibrovascular membrane between the aspect of the lens and the astrocytic component of the mass. Glial fibrillary acidic protein (GFAP) showed a variable intracytoplasmic reaction in the astrocytic proliferation, involving approximately 50% of the cells. Tissue culture studies showed a fairly rapid proliferation of fusiform cells, consistent with bipolar astrocytic cells. Cytogenetic studies showed one abnormal clone consisting of three hyperdiploid cells with a loss of chromosome 9 and a gain of chromosomes 6 and 12. CONCLUSION: The atypical localization of the retinal tumor could be explained by the fact that it was trapped during its proliferation by the retinal detachment associated with the PHPV.

Astrocytoma↗
PubMed1997

Corneal endothelial cell density in glaucoma.

PURPOSE: We studied corneal endothelial cell density in patients with glaucoma. METHODS: One hundred two patients with glaucoma were compared with 52 patients without glaucoma of the same age group. Exclusion criteria included history of either corneal disease, ocular inflammation, trauma, or surgery other than peripheral iridectomy. The following data were extracted from the patient files: glaucoma type and duration, laser treatments, glaucoma medications, and documented intraocular pressure (IOP) measurements. Specular microscopies were performed on central corneas, endothelial images were analyzed by computerized planimetry, and cell counts were calculated. RESULTS: Corneal endothelial cell counts were significantly lower in patients with glaucoma (2,154 +/- 419 cells/mm2) than in controls (2,560 +/- 360 cells/mm2; t test, p < 0.0001). In the glaucoma group, cell counts were inversely proportional to the means of IOPs. Patients receiving three or four glaucoma medications had lower cell counts than those receiving one or two medications. Cell counts were significantly lower both in primary angle-closure glaucoma and in primary open-angle glaucoma. CONCLUSION: This study suggests that patients with glaucoma may have lower corneal endothelial cell density than those without glaucoma of the same age group. The proposed mechanisms are direct damage from IOP, congenital alteration of the corneal endothelium in patients with glaucoma, glaucoma medication toxicity, or a combination of these.

Aged↗
PubMed1990

Congener-specific analysis of the accumulation of polychlorinated biphenyls (PCBs) by aquatic organisms in the maximum turbidity zone of the St. Lawrence estuary, Québec, Canada.

The polychlorinated biphenyl (PCB) contamination of the biota of the St. Lawrence estuary maximum turbidity zone (MTZ) was investigated. The species analyzed consist of zooplankton (mostly Neomysis americana), larval smelt (Osmerus mordax), juvenile smelt, juvenile tomcod (Microgadus tomcod) and adult smelt, tomcod and capelin (Mallotus villosus). A significant increase in total PCB contamination from zooplankton to all fish developmental stages indicates that the St. Lawrence MTZ is a site of significant PCB contamination. The total PCB contamination of adult smelt and tomcod sampled in the St. Lawrence MTZ was greater than the limit of 0.1 ppm set by the International Joint Commission for the protection of predators. For zooplankton, tomcod and capelin, significant correlations were found between lipid content and PCB contamination. The congener-specific analyses showed that the bioconcentration factor of the individual congeners varied with the species involved and with the molecular structure of the congener. It was found that the chlorine atoms in positions 2, 4 and 5 on at least one phenyl ring of the PCB molecule was a dominant factor causing accumulation of PCBs in aquatic organisms. The pattern of PCB congeners found in beluga (Delphinapterus leucas) whale tissues is similar to the PCB pattern found in the St. Lawrence estuary MTZ biota.

Animals↗