PubMed Health⌕ Search

Biomedical subjects

D Martineau

Publications and source records attributed to D Martineau.

At least 37 records · Page 2Linked to original sources
PubMed1999

Functional role of local angiotensin-converting enzyme (ACE) in adrenal catecholamine secretion in vivo.

The aim of the present study was to investigate whether exogenous angiotensin I (AngI) is locally converted to angiotensin II (AngII), which in turn results in an increase in the adrenal catecholamine (CA) secretion in the adrenal gland in anesthetized dogs. Plasma CA concentrations in adrenal venous and aortic blood were determined by an HPLC-electrochemical method. Adrenal venous blood flow was measured by gravimetry. Local administration of AngI (0.0062 to 6.2 microg, 0.0096 to 9.6 microM) to the left adrenal gland resulted in significant increases in CA output in a dose-dependent manner. Following administration of 0.62 microg (0.96 microM) of AngI, adrenal epinephrine and norepinephrine outputs increased from 20.8+/-13.6 to 250.9+/-96.4 ng x min(-1) x g(-1) (p<0.05, n = 5) and from 2.8+/-1.7 to 29.6+/-11.1 ng x min(-1) x g(-1) (p<0.05, n = 5), respectively. From the same left adrenal gland, the output of AngII increased from -0.02+/-0.04 to 26.39+/-11.38 ng x min(-1) x g(-1) (p<0.05, n = 5), while plasma concentrations of AngII in aortic blood remained unchanged. In dogs receiving captopril (12.5 microg, 0.5 mM) 10 min prior to AngI, the net amounts of CA and AngII secreted during the first 3 min after AngI were diminished by about 80% (p<0.05, n = 5) compared with those obtained from the control group. There was a close correlation (r2 = 0.91, n = 6) between the net increases in AngII and CA outputs induced by AngI. The results indicate that the local angiotensin converting enzyme is functionally involved in regional AngII formation in the canine adrenal gland in vivo. The study suggests that AngII thus generated may play a role in the local regulation of adrenal CA secretion.

Adrenal Glands↗
PubMed1998

Effects of in vitro exposure of beluga whale leukocytes to selected organochlorines.

The effects of in vitro exposure to different organochlorines were evaluated on immune functions of beluga whale peripheral blood leukocytes and splenocytes. The effects of different concentrations of four different congeners of PCBs (138, 153, 180, and 169) as well as two DDT metabolites (p,p'-DDT and p,p'-DDE) were evaluated on phagocytosis and cell proliferation. The effects of dioxins and mixtures of organochlorines were also evaluated on cell proliferation. The different compounds tested had no marked effect on phagocytosis. PCB 138 and p,p'-DDT, but not PCB 153, PCB 180, PCB 169, and p,p'-DDE, reduced significantly the proliferative response of beluga splenocytes cultured either with or without phytohemagglutinin A (PHA). Proliferation of beluga splenocytes was not markedly affected by exposure to 5 ppm of PCB 138, 153, 180, and 169 separately. Exposure to a mixture of congeners 138, 153, and 180 (5 ppm each) significantly reduced splenocytes proliferation, but not the mixture of congeners 138, 153, 180, and 169 (5 ppm each). TCDD did not affect cell proliferation in our study. The reduced proliferation of beluga cells exposed in vitro to mixtures of organochlorines at concentrations in the range of those observed in tissues of St. Lawrence belugas might provide a basis to support the hypothesis that contaminants induce immunosuppression in these animals.

Animals↗
PubMed1998

Use of polymerase chain reaction and immunohistochemistry for detection of canine adenovirus type 1 in formalin-fixed, paraffin-embedded liver of dogs with chronic hepatitis or cirrhosis.

To assess the possible involvement of canine adenovirus type 1 (CAV-1) in naturally occurring cases of canine chronic liver disease, a polymerase chain reaction (PCR)-based assay was developed to detect a conserved region of the major core protein gene (pVII) of CAV-1 in formalin-fixed, paraffin-embedded liver sections. Results were compared with a standard avidin-biotin immunoperoxidase complex technique that detected CAV-1 antigens using a commercial monoclonal anti-adenovirus antibody. Seventeen cases of cirrhosis and 28 cases of chronic hepatitis with piecemeal necrosis and progressive fibrosis were selected for the study. Formalin-fixed, paraffin-embedded liver sections of 2 cases of infectious canine hepatitis (ICH) and crude DNA extract from CAV-1 (ATCC VR 293 Utrecht strain) served as positive controls. A 411-base-pair viral region was amplified and sequenced as CAV-1 pVII in both cases of infectious canine hepatitis and in the CAV-1 crude DNA extract. The 2 ICH cases were positive for CAV-1 antigens by the immunoperoxidase method. CAV-1 DNA or antigens were not detected by either technique in any of the 45 cases of chronic liver disease selected for the study. These results indicate that both PCR and immunohistochemistry are reliable and rapid techniques for detecting CAV-1 in formalin-fixed, paraffin-embedded liver sections of dogs with ICH. Several possibilities may explain the negative results obtained with both techniques in this study, including the noninvolvement of CAV-1 in canine chronic hepatitis and cirrhosis and the possibility that the virus causes initial damage, provokes a self-perpetuating chronic liver disease, and disappears.

Adenoviridae Infections↗
PubMed1998

Neoplastic and nonneoplastic hepatic changes in lake whitefish (Coregonus clupeaformis) from the St. Lawrence River, Quebec, Canada.

As part of a survey of fish diseases, lake whitefish (Coregonus clupeaformis) were collected in fall 1995 from the St. Lawrence River 15 km upstream of Quebec City, Quebec, Canada, to assess the prevalence of liver lesions. A total of 141 fish were captured and necropsied, and three standard sections of liver were taken for histological examination. Prevalences of altered hepatocyte foci, hepatocellular carcinoma, cholangioma, and cholangiocarcinoma were 0.7%, 2.1%, 0.7%, and 2.1%, respectively. Thus, the overall prevalence of liver neoplasia was 4.9% (7/141). Hepatic tumors were only observed in fish 7 years old or older. Fish age was significantly and positively correlated with the index assessing the number and size of macrophage aggregates (p<0.001; rs = 0.16). Hepatocyte vacuolation, anisokaryosis, lymphocytic infiltration, and bile duct hyperplasia were also observed but were not related to the age, length, sex, or condition factor of the fish. These results represent the first report on a series of hepatic tumors in a wild salmonid species.

Adenoma, Bile Duct↗
PubMed1998

Uterine adenocarcinoma with abdominal carcinomatosis in a beluga whale.

A case of uterine adenocarcinoma is reported in a 26-yr-old, free-ranging beluga whale (Delphinapterus leucas) from the St. Lawrence estuary (Quebec, Canada). This neoplasm appeared as a segmental stenotic thickening of the left uterine horn composed of well differentiated, but disorganized and infiltrative, glandular structures surrounded by an extensive scirrhous stroma. Abdominal carcinomatosis was observed on the mesosalpinx and on the serosal aspect of the gastric compartments. This is the first report of a malignancy originating in the uterus of a cetacean.

Abdominal Neoplasms↗
PubMed1997

Immune functions in beluga whales (Delphinapterus leucas): evaluation of natural killer cell activity.

Natural killer (NK) activity, an important non-specific defense mechanism against viral infections and tumors, was demonstrated in beluga whales using two different methods: 51Cr release and flow cytometry. Using the 51Cr release assay, NK activity in belugas was shown to be higher against K-562 than against YAC-1 cell lines. Moreover, it was enhanced by the addition of human recombinant interleukin-2 with both cell lines. NK activity evaluated by flow cytometry in the peripheral blood of eight belugas increased when the effector:target cell (E:T) ratio increased, and averaged 13.9% +/- 3.8% (range 9.9% to 17.8%) at an E:T ratio of 100:1. While NK activity could be readily detected using both methods, the lack of radio-isotopes and related laboratory room make the flow cytometric method a viable and safe alternative. The evaluation of this function in cetaceans could lead to a better understanding of the early events that lead to viral epizootics in populations of marine mammals in different parts of the world, as well as to the high prevalence of neoplasms in St. Lawrence beluga whales.

Animals↗
PubMed1997

Evaluation of PCR and ELISA assays for screening clinical trial subjects for replication-competent retrovirus.

Gene delivery via murine-based recombinant retroviral vectors is currently widely used in gene therapy clinical trials. The vectors are engineered to be replication defective by replacing the structural and nonstructural genes of a cloned infectious retrovirus with a therapeutic gene of interest. The retroviral particles are currently generated in packaging cell lines, which supply all retroviral proteins in trans. Recombination between short homologous regions of the retroviral vector and packaging cell line elements can theoretically generate replication-competent retrovirus (RCR) and hence the Food and Drug Administration (FDA) requires the monitoring of clinical trial subjects for the presence of RCR. Sensitive polymerase chain reaction (PCR) assays have been used for the detection of murine leukemia virus (MLV) nucleotide sequences in peripheral blood mononuclear cells (PBMCs). A novel serological enzyme-linked immunosorbent assay (ELISA) for the detection of anti-MLV specific immunoglobulin (Ig) has been developed to be used as an alternative to the PCR assay. Both assays were used to monitor human immunodeficiency virus (HIV)-positive clinical trial subjects who had received multiple injections of HIV-IT (V), a retroviral vector encoding HIV-1 IIIBenv/rev. Western blot analysis and an in vitro vector neutralization assay were used to characterize further a subset of serum samples tested by ELISA. Results show no evidence of RCR infection in clinical trial subjects. PCR and ELISA assays are discussed in terms of their advantages and limitations as routine screening assays for RCR. The PCR assay is our current choice for monitoring clinical trial subjects receiving direct administration of vector, and the ELISA is our choice for those receiving ex vivo treatment regimens.

Antibodies, Viral↗
PubMed1997

Anti-vector immunoglobulin induced by retroviral vectors.

Replication-incompetent retroviruses have been employed as gene therapy vectors in experimental settings for more than a decade. More recently, these vectors have been tested in the clinic as immunotherapeutic agents and anticancer agents. One potential problem with the use of such vectors is the possible development of immune responses directed against the vector particles themselves. Here, we examine immunoglobulin (Ig) responses specific for retroviral vectors derived from murine leukemia virus (MLV). Anti-MLV Ig is seen following intramuscular (i.m.) administration of retroviral vectors in mice, and in nonhuman primates; as expected, these responses are dependent upon the vector dose delivered. Furthermore, serum from vector-treated animals is capable of partially neutralizing vector-mediated transduction of target cells in an in vitro assay. Nevertheless, even in the presence of significant levels of anti-vector Ig in vivo, i.m. administration of retroviral vector is still capable of driving both Ig and cytotoxic T lymphocyte (CTL) responses specific for vector-encoded gene products. This work suggests that although retroviral vectors may readily induce immune responses directed against the vector particles themselves, such responses will not significantly affect the efficiency of these vectors in an immunotherapeutic protocol.

Animals↗
PubMed1997

Adrenal hyperplastic and degenerative changes in beluga whales.

Thirty stranded beluga whales (Delphinapterus leucas) from the St. Lawrence Estuary (Quebec, Canada) population and five animals from the Hudson Bay aboriginal hunt (North-west Territories, Canada) were examined. Twenty one animals from the St. Lawrence Estuary had mild to severe adrenal lesions and four whales from the Hudson Bay population were affected by minimal adrenal changes. Cortical hyperplasia was observed in 24 adult beluga whales all from the St. Lawrence Estuary. Bilateral cortical cysts and cellular vacuolar degeneration were observed in the adrenal glands of 19 beluga whales from both populations. The cysts, filled with a cortisol-rich liquid, were present in both sexes. Beluga whales with adrenal cysts were significantly older than animals without cysts, and the severity of the lesions increased with age. Nodular hyperplasia of the medulla was observed in seven of the beluga whales, all from the St. Lawrence Estuary population. All lesions could be part of a normal aging process. The adrenocortical lesions might be due to stress or adrenocorticolytic xenobiotics, while the medullary hyperplasia might be caused by hypoxia or exposure to estrogenic xenobiotics.

Adrenal Gland Diseases↗
PubMed1997

The Canadian Cooperative Wildlife Health Centre and surveillance of wild animal diseases in Canada.

The Canadian Cooperative Wildlife Health Centre (CCWHC) was established in 1992 as an organization among Canada's 4 veterinary colleges, with a mandate to apply veterinary medicine to wildlife management and conservation in Canada. A major function of the CCWHC is nation-wide surveillance of wild animal diseases. Disease surveillance is conceived as consisting of 4 different activities: detection, diagnosis, information management, and use of information. In the CCWHC surveillance program, detection of disease is carried out by a wide range of professional and avocational field personnel, and much effort is expended to stimulate and support this activity. Diagnosis is done by personnel of provincial and federal veterinary laboratories and the CCWHC. Information management is achieved through a national database of wildlife disease incidents developed and maintained by the CCWHC. Use of information is enabled through established channels for distribution of information derived from the surveillance program to persons responsible for wildlife programs and policies, and to the public. There has been a high demand for the services of the CCWHC since its establishment. The CCWHC responds to approximately 2000 requests for information annually, distributes its newsletter to over 1700 recipients, examines approximately 1200 wild animal submissions each year, and has accumulated records of over 5000 disease incidents in its database. Technical information from the CCWHC has benefited federal, provincial/territorial, and nongovernment wildlife agencies; endangered species recovery programs; federal and provincial veterinary services; and federal and provincial public health programs.

Animal Diseases↗
PubMed1996

Phylogenetic and epidemiologic analysis of the walleye dermal sarcoma virus.

Walleye dermal sarcoma virus (WDSV) is a newly described retrovirus that is etiologically associated with a multifocal skin tumor of a fish common in North America, the walleye. Tumor prevalence ranges from 27% of adult walleyes in a densely populated lake, Oneida Lake, New York, to 1% in less populated waters. Phylogenetic analysis of the surface (SU) domain of the WDSV envelope gene of isolates from different regions of North America showed that viral isolates formed distinct clusters according to their geographic origin, except viral isolates from Oneida Lake, which were also much more variable. Viral clones isolated from an individual tumor had identical nucleotide sequences. This finding is consistent with tumors developing from single infected dermal cells, and supports the etiological role of this virus in tumor development. Like in other retroviruses, the SU domain of the WDSV env gene was more variable than gag, and the ratio of nonsynonymous over synonymous mutations was comparable to that of the V3 loop of HIV-1. These findings indicate that WDSV SU is the object of strong selective immunologic pressures, like the SU domain of other retroviruses.

Base Sequence↗
PubMed1996

Immune functions in beluga whales (Delphinapterus leucas): evaluation of mitogen-induced blastic transformation of lymphocytes from peripheral blood, spleen and thymus.

A quantitative assay was developed to evaluate mitogen-induced lymphoblastic transformation in beluga whales (Delphinapterus leucas) using peripheral blood mononuclear cells, splenocytes and thymocytes. Optimal concentrations of four different mitogens (Con-A, PHA, LPS and PWM) were determined with the use of standard curves. Addition of human recombinant IL-2 (rhIL-2) after 48 h in culture with the different mitogens suggests that Con-A, PHA and PWM, but not LPS, stimulate T cells in belugas, as they do in other animal species. The addition of 2-mercaptoethanol did not enhance significantly the proliferation of cells stimulated by Con-A, PHA and LPS, while it did with the cells stimulated by PWM and those cultured without mitogen. The proliferative response of cells was suppressed when the culture medium was supplemented by beluga serum instead of fetal calf serum. This assay will be useful to assess the status of the immune functions in different populations of beluga whales as well for further in vitro immunotoxicological experiments.

Animals↗
PubMed1996

Single-tube heminested PCR coupled with 'touchdown' PCR for the analysis of the walleye dermal sarcoma virus env gene.

The nucleotide sequences of geographically distant isolates of a newly characterized retrovirus of fish, the walleye dermal sarcoma virus (WDSV) were compared. Primers were designed based on the nucleotide sequence of a single molecular clone isolated from a tumor collected from a fish in New York state, USA. Conventional polymerase chain reaction (PCR) did not allow the satisfactory amplification of WDSV isolates from a different geographic region (Quebec, Canada), probably owing to the high genetic variability of retroviruses. To allow the successful amplification of Quebec WDSV isolates, heminested PCR and 'touchdown' PCR were combined in a highly sensitive, short and simple protocol taking place in a single tube, thus minimizing cross contamination. This technique allowed the first unambiguous detection of a fish retrovirus in Canada and the phylogenetic analysis of various geographic isolates of this virus. Other potential applications for this technique include PCR amplification using degenerate primers, and amplification of templates with some expected degree of genetic variability.

Animals↗
PubMed1996

Functional evidence for L-type Ca2+ channels controlling ANG II-induced adrenal catecholamine release in vivo.

The aim of the present study was to investigate the functional involvement of L- and/or N-type Ca2+ channels in adrenal catecholamine secretion in response to exogenous angiotensin II (ANG II) in anesthetized dogs. Plasma catecholamine concentrations in adrenal venous and aortic blood were determined by a high-performance liquid chromatography-electrochemical method. In the first series of experiments, repeated infusions of BAY K 8644 locally into the left adrenal gland at 15-min intervals resulted in significant and reproducible increases in adrenal catecholamine secretion. Nifedipine, similarly administered 5 min before BAY K 8644, diminished BAY K 8644-induced catecholamine secretion in a dose-dependent manner and completely blocked the catecholamine response at the highest dose tested. In the second series of experiments, local infusion of ANG II resulted in a significant increase in adrenal catecholamine secretion. The maximum catecholamine response to ANG II was attenuated by approximately 65% in the presence of nifedipine at the dose that abolished the BAY K 8644-induced catecholamine release. This inhibition by nifedipine remained unchanged in the presence of omega-conotoxin. The present study shows that dihydropyridine-sensitive L-type Ca2+ channels are operative in the adrenal medulla of the dog in vivo. The results indicate that the L-type Ca2+ channels are only partially implicated in the local regulation of ANG II-induced adrenal catecholamine secretion, suggesting the existence of another mechanism. However, omega-conotoxin-sensitive N-type Ca2+ channels are unlikely to be functionally involved in postsynaptic mechanisms mediating adrenal catecholamine secretion in response to exogenous ANG II under in vivo conditions.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1996

Myeloencephalitis associated with a viridans group Streptococcus in a colony of Japanese macaques (Macaca fuscata).

Five weaned immature Japanese macaques (Macaca fuscata), bred in captivity, showed nervous signs over a 12-month period. Hemorrhagic cerebral infarcts with vasculitis were detected in four necropsied animals. The distribution and nature of the lesions were consistent with bacterial embolism, and a Streptococcus isolate, biochemically similar to S. salivarius, was recovered from the cerebral lesions from three of the four necropsied macaques. Treatment with antibacterial agents (enrofloxacin) improved the clinical condition of the surviving affected animal. These observations strongly suggest that this Streptococcus spp., member of the viridans group, is responsible for this outbreak. Dental pulpitis, present in two of the four macaques, probably served as the entry for this bacterium.

Animals↗