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Biomedical subjects

D Martineau

Publications and source records attributed to D Martineau.

At least 19 recordsLinked to original sources
PubMed2004

Seroprevalence of Toxoplasma gondii in Canadian pinnipeds.

Sera (n = 328) collected from phocids (1995-97) from the east coast of Canada, including harp seals (Phoca groenlandica), hooded seals (Cystophora cristata), grey seals (Halichoerus grypus), and harbor seals (Phoca vitulina), were diluted 1:25, 1:50, and 1:500 and tested by a modified agglutination test for antibodies to Toxoplasma gondii. Titers equal to or greater than 1:25 were considered evidence of exposure. Grey seal (11/122, 9%), harbor seal (3/34, 9%), and hooded seal (1/60, 2%) had titers of 1:25 and 1:50. Harp seals (n = 112) were seronegative. Probable maternal antibody transfer was observed in one harbor and one grey seal pup at 10 and 14 day of age, respectively. Transmission of T gondii in the marine environment is not understood. The discovery of T. gondii in marine mammals might indicate natural infections unknown because of lack of study or might indicate recent contamination of the marine environment from the terrestrial environment by natural or anthropogenic activities.

Age Factors↗
PubMed2003

Postnatal bone marrow stromal cells elicit a potent VEGF-dependent neoangiogenic response in vivo.

Bone marrow stromal cells (MSCs) are pluripotent cells capable of differentiation into several tissue types. This present study was performed to determine their functional neoangiogenic potential in vivo. Whole bone marrow was harvested from C57Bl/6 mice, and the adherent cellular fraction was culture expanded for 14 doublings. These MSCs were resuspended in Matrigel and their angiogenic effect assessed in isogenic recipients. At 2 weeks postimplantation, the mean vascular density in Matrigel plugs containing 2 x 10(6) MSCs/ml was 41+/-5.0 blood vessels (BVs)/mm(2) compared to 0.5+/-0.7 for empty Matrigel (P<0.001). In comparison, Matrigel plugs containing either recombinant murine VEGF 165 at 50 ng/ml or bovine bFGF at 1000 ng/ml generated 21+/-5 and 11+/-2.0 BV/mm(2), respectively. Arteriogenesis was observed only in the MSC-containing implants. With the use of LacZ retroviral labeling of ex vivo expanded MSCs, we show that approximately 10% of LacZ(+)MSCs differentiated into CD31(+) and VEGF(+) endothelial cells. More than 99% of the neoangiogenic phenomena arose from recruitment of host-derived LacZ(null) vascular structures. Neutralizing anti-VEGF antibodies inhibited the MSC-initiated angiogenic response in vivo by 85% (P<0.001). In conclusion, MSCs have the ability to effectively recruit and participate in angiogenesis and arteriogenesis de novo and VEGF plays a central role in the observed host-derived angiogenic response. We propose that ex vivo expanded autologous MSCs may serve as cell therapy to promote therapeutic angiogenesis.

Animals↗
PubMed2003

Adenomatous hyperplasia of the thyroid gland in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary and Hudson Bay, Quebec, Canada.

We evaluated thyroid gland lesions in beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (n = 16) and Hudson Bay (n = 14). Follicular cysts and nodules of adenomatous hyperplasia of the thyroid gland were found in eight and nine adults from the St. Lawrence Estuary (n = 10), respectively, and in four and six adults from Hudson Bay (n = 14), respectively. The total volume of the lesions of thyroid adenomatous hyperplasia was positively correlated with age in both populations. Comparison between populations could not be performed because of differences in age structures of sample groups. Beluga whales from both populations have unique thyroid lesions among marine mammals.

Age Factors↗
PubMed2001

Dermatophilus-like infection in beluga whales, Delphinapterus leucas, from the St. Lawrence estuary.

Six beluga whales (Delphinapterus leucas) found dead on the shores of the St. Lawrence estuary had multiple slightly depressed greyish round areas randomly distributed over the whole body. Histologically, the surface of these areas was covered with a thick layer of Dermatophilus-like organisms which invaded the stratum corneum. The underlying stratum spinosum had marked spongiosis and vacuolar degeneration. Minimal neutrophilic infiltration was present within the underlying dermal papillae. To the authors' knowledge, dermatophilosis in cetaceans has not been reported previously.

Animals↗
PubMed2001

Comparison of serum interleukin-10 (IL-10) levels between normal volunteers and patients with advanced melanoma.

Melanoma is an immunoresponsive malignancy. Interleukin-10 (IL-10) is a potent regulator of immunosuppression. The purpose of this research was to define the relationship of serum IL-10 to survival in patients with metastatic melanoma. Forty-one melanoma patients and 50 normal volunteers were analyzed. The median IL-10 level as determined by enzyme-linked immunosorbent assay (ELISA) in melanoma patients was 8.75 pg/ml compared to < 3.0 pg/ml in normal volunteers (p = 0.0001). Survival of melanoma patients with an IL-10 level above 10.0 pg/ml was 365 days compared to 557 days in patients with IL-10 levels less than 10.0 pg/ml (p = 0.0259, Wilcoxon). Elevated IL-10 levels were correlated with poor survival.

Adult↗
PubMed2001

Seroprevalence of antibodies to Toxoplasma gondii in lynx (Lynx canadensis) and bobcats (Lynx rufus) from Québec, Canada.

The seroprevalence of antibodies to Toxoplasma gondii was investigated in trapped lynx (Lynx canadensis) and bobcats (Lynx rufus) from Québec, Canada. Forty-seven of 106 (44%) lynx and 4 of 10 (40%) bobcats had positive titers for T. gondii (> or = 25) by means of the modified agglutination test incorporating mercaptoethanol and formalin-fixed tachyzoites. Seroprevalence was significantly higher (P < 0.0001) in adult lynx than in juvenile lynx. The presence of antibodies to T. gondii in lynx and bobcats suggests that this organism is widespread in the wild and that exposure to wild felids and game animals from Québec may represent a potential source of infection for humans.

Age Factors↗
PubMed2000

Suprasellar germinoma in three lake whitefish (Coregonus clupeaformis).

Suprasellar germinomas were identified in three wild-caught lake whitefish (Coregonus clupeaformis) from the St. Lawrence River, Quebec, Canada. Histologically, the three tumors expanded the subarachnoid space of the ventral surface of the brain immediately adjacent to the pituitary gland and, in one case, infiltrated the adjacent neuropil. These tumors were characterized by nests and sheets of round cells with a high mitotic rate, separated by a scant amount of loose fibrovascular stroma. The stroma was infiltrated by a moderate number of small mononuclear cells, including rare CD3-immunoreactive lymphocytes. This is the first report of intracranial germinoma in a fish species.

Animal Diseases↗
PubMed2000

Toxoplasmosis in beluga whales (Delphinapterus leucas) from the St Lawrence estuary: two case reports and a serological survey.

Toxoplasmosis was diagnosed in two free-ranging beluga whales from the St Lawrence estuary, Quebec, Canada, in 1988 and 1998. Histologically, tachyzoites and bradyzoites were present in the brain, spleen, lymph nodes, adrenals and lungs of both animals, and in the thymus of one. These organisms were readily labelled by an indirect immunohistochemical method for Toxoplasma gondii antigens. In the lymph nodes, spleen and lungs the organisms were associated with histiocytic infiltration. In the brain of one animal they were associated with mild multifocal gliosis and haemorrhages. There was no evidence of concomitant morbillivirus infection. Serum samples were collected from 22 beluga whales stranded between 1995 and 1998 on the shores of the St Lawrence Estuary and examined for antibodies to T. gondii by the modified agglutination test. Antibody titres of s25 were found in six (27%) of the animals. This is the first confirmed report of toxoplasmosis in beluga whales.

Animals↗
PubMed2000

Fibroleiomyomas of the tubular genitalia in female beluga whales.

Fibroleiomyomas of the tubular genitalia were diagnosed in 6 of 9 adult female beluga whales from the St. Lawrence estuary, Quebec, Canada. These tumors were located in the vagina (6 of 6), the cervix (2 of 6), and the uterus (1 of 6). Endogenous hormones or xeno-estrogens may be implicated in the occurrence of these tumors.

Animals↗
PubMed1999

Functional characterization of a piscine retroviral promoter.

Walleye dermal sarcoma virus (WDSV) is a retrovirus aetiologically associated with a multifocal skin tumour of walleye. Tumours synchronously develop on 27% of fish and regress seasonally; their severity is influenced by water temperature. To functionally characterize the LTR of WDSV, the LTR was fused to the luciferase reporter gene. WDSV LTR was found to be transcriptionally active in both fish and mammalian cells. WDSV LTR deletion mutants were constructed to identify specific regions that were functionally important in modulating viral gene expression and in temperature responsiveness. The 5' end 60 bp, which contain a putative ecdysone-response element also present in another fish retrovirus, positively modulated transcription from the WDSV LTR at 25 degrees C, but not at lower temperatures. A 13 bp region (nt -288 to -275) comprising a putative activator protein-1 element was necessary for maintaining WDSV LTR activity at all temperatures. In marked contrast to the short direct repeats found in mammalian retroviral LTRs, five 5 bp direct repeats (nt -336 and -272) were found to negatively regulate transcription from the WDSV LTR. A region spanning nt -440 to -218 stimulated the activity of a heterologous mammalian promoter in an orientation-dependent manner, modestly in fish cells (1.3- to 2-fold), but markedly (3.7- to 5.1-fold) in mammalian cells. Our results strongly suggest that the putative promoter elements present in the WDSV LTR function differentially in a temperature-specific manner and that complex interactions between these elements modulate WDSV LTR activity in response to temperature changes.

Animals↗
PubMed1999

Walleye dermal sarcoma virus: OrfA N-terminal end inhibits the activity of a reporter gene directed by eukaryotic promoters and has a negative effect on the growth of fish and mammalian cells.

Walleye dermal sarcoma virus (WDSV) is a fish retrovirus causing a skin tumor termed walleye dermal sarcoma, which develops and regresses on a seasonal basis. The WDSV genome contains three short open reading frames designated orfA, orfB, and orfC in addition to the viral structural genes, gag, pol, and env. orfA and orfB transcripts are detected in tumors by reverse transcription-PCR. Recently, OrfA, whose amino acid sequence is similar to that of cyclins A and D, has been shown to complement a cyclin-deficient yeast strain. We report that expression of the accessory gene orfA inhibited nonspecifically the activity of a reporter gene directed by various eukaryotic promoters. In addition, stable transfection with the wild-type orfA generated substantially fewer G418-resistant colonies in both fish and mammalian cells than the parent vector. An orfA mutant expressing only the first N-terminal 49 residues of the full-length protein had the same negative effect on the activity of the reporter gene and on the number of stably transfected colonies as the full-length OrfA. Thus, OrfA inhibits cell growth and/or causes cell death, and the first 49 N-terminal residues of this protein are sufficient to cause these negative effects.

Amino Acid Sequence↗
PubMed1999

Modulation of adrenal catecholamine release by PACAP in vivo.

The aim of the present study was to investigate whether pituitary adenylate cyclase-activating polypeptide-(1-27) (PACAP27) can modulate the adrenal catecholamine (CA) secretion induced by splanchnic nerve stimulation (SNS) and by exogenous acetylcholine (ACh) in anesthetized dogs. Plasma CA concentrations in adrenal venous and aortic blood were quantified by a high-performance liquid chromatography coupled with electrochemical detection. Adrenal venous blood flow was measured by gravimetry. Local infusion of PACAP27 (0.5, 5, and 50 ng) to the left adrenal gland via the adrenolumbar artery resulted in an increase in CA output, reaching a significant level at the highest dose tested. Either direct SNS (2 Hz) or local infusion of ACh (0.5 microgram) to the left adrenal gland produced significant increases in CA output to an extent similar to that obtained with 50 ng of PACAP27 alone. In the presence of PACAP27 (50 ng), CA responses to either SNS or exogenous ACh were significantly potentiated by approximately four- and sixfold, respectively, compared with those obtained in response to each stimulus alone. However, the enhanced CA responses to ACh were not significantly different from those to SNS. The results indicate that the increase in adrenal CA secretion, induced by either direct SNS or exogenous ACh, is synergistically enhanced by PACAP27. The study suggests that the enhanced CA secretion may result from the activation of a PACAP-mediated facilitatory mechanism(s) localized presumably at the postsynaptic level in the canine adrenal medulla in vivo, although the possible involvement of presynaptic mechanisms cannot completely be ruled out in the present study.

Acetylcholine↗
PubMed1999

Bone fluoride concentrations in beluga whales from Canada.

Beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary have been reported to have dental and bone abnormalities. To determine whether these lesions could be caused by high exposure to fluorides, we measured bone fluoride levels in eight beluga whales stranded on the shores of the St. Lawrence Estuary (Quebec, Canada), and in nine beluga whales killed by Inuit hunters in the Hudson Bay (North Western Territories, Canada). In both groups, fluoride concentrations were higher than those found in terrestrial mammals intoxicated by fluorides. Unexpectedly, fluoride concentration was significantly higher in beluga whales from the Hudson Bay (mean +/- SD: 10.365 +/- 1.098 ppm) than in beluga whales from the St. Lawrence Estuary (4.539 +/- 875 ppm) and was positively correlated with age in the latter population. Differences in diet might explain the differences in fluoride concentrations found between these two populations.

Aging↗
PubMed1999

Respiratory nematodiases in raptors in Quebec.

This is a retrospective study on wild raptors submitted to the Université de Montréal (Quebec, Canada) from 1989 to 1996. Cyathostoma spp. (Nematoda: Syngamidae) adults and/or eggs were found in air sacs, lungs, bronchi, and trachea of 12 raptors (Falconiformes and Strigiformes) from Quebec, Canada, belonging to eight different species, five of which are first host records for this parasite: barred owl (Strix varia), snowy owl (Nyctea scandiaca), northern harrier (Circus cyaneus), northern goshawk (Accipiter gentilis), and broad-winged hawk (Buteo platypterus). The infection was considered fatal in four birds, while no significant clinical signs were observed in the other cases. Major pathologic changes included diffuse pyogranulomatous air sacculitis, pneumonia, and bronchitis. A few unidentified larval nematodes embedded in a granuloma were found in the lungs of an additional Coopers' hawk (Accipiter cooperii); they were not considered clinically significant. A dead nematode, surrounded by necrotic inflammatory cells, was found in the air sac of a northern goshawk. The presence of nematodes in air sacs or lungs should be considered in wild raptors demonstrating respiratory problems.

Air Sacs↗
PubMed1999

Functional involvement of angiotensin AT2 receptor in adrenal catecholamine secretion in vivo.

The aim of the present study was to analyse modulations of adrenal catecholamine secretion from the adrenal gland of anesthetized dogs in response to locally administered angiotensin II (AngII) in the presence of either PD 123319 or CGP 42112, both of which are highly specific and selective ligands to angiotensin AT2 receptor. Plasma concentrations of epinephrine and norepinephrine in adrenal venous and aortic blood were quantified by a high performance liquid chromatography coupled with electrochemical detection (HPLC-EC) method. Adrenal venous blood flow was measured by gravimetry. Local administration of AngII (0.05 microg, 0.1 microM) to the left adrenal gland increased adrenal gland catecholamine output more than 30 times that found in nonstimulated states. Administration of either PD 123319 (0.085 microg (0.23 microM) to 8.5 microg (23 microM)) or CGP 42112 (0.005 microg (0.01 microM) to 5 microg (10 microM)) did not affect the basal catecholamine output significantly. The increase in adrenal catecholamine output in response to AngII was inhibited by approximately 80% following the largest dose of PD 123319. CGP 42112 significantly attenuated the catecholamine response to AngII by approximately 70%. PD 123319 and CGP 42112 were devoid of any agonist actions with respect to catecholamine output by the adrenal gland in vivo. Furthermore, both PD 123319 and CGP 42112 inhibited the increase in adrenal catecholamine secretion induced by local administration of AngII. The present study suggests that AT2 receptors play a role in mediating catecholamine secretion by the adrenal medulla in response to AngII receptor agonist administration in vivo.

Adrenal Glands↗