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Biomedical subjects

G Tremblay

Publications and source records attributed to G Tremblay.

At least 19 recordsLinked to original sources
PubMed1992

Rat prostate adenocarcinoma cells disseminate to bone and adhere preferentially to bone marrow-derived endothelial cells.

Approximately 70% of patients with prostatic cancer develop bone metastases. Metastatic prostate adenocarcinomas are associated with high mortality rates and represent a leading cause of cancer-related deaths among males. To study the host-tumor interactions underlying the predilection of prostate cancer cells for skeletal bone, an experimental model was developed using rat Dunning carcinoma Mat-LyLu cells. Inoculations of these cells into the left ventricle of the heart led to the development of spinal metastases in 100% of inoculated animals. A subline of Mat-LyLu (Mat-LyLu-B5) was subsequently selected through the sequential inoculation of bone marrow-derived carcinoma cells into the left ventricle and was found to have an increased metastatic potential compared to the parental line. The possible role of tumor cell adhesion to host cells in the process of bone marrow colonization was then investigated in vitro using the metastatic line and primary cultures of rat bone marrow-derived stromal cells. It was found that the adhesion of the metastatic Mat-LyLu cells to a bone marrow stromal cell culture highly enriched for endothelial cells was significantly higher than the adhesion to other bone-derived cells, including nonendothelial bone marrow stromal cells (3.5x) and osteoblasts (1.7x). It was also significantly higher than the adhesion to rat fibroblasts (7x) and to hepatic endothelial cells (7.5x). The results suggest that the adhesion of prostate carcinoma cells to the bone marrow endothelium may play a role in their metastasis to bone.

Adenocarcinoma↗
PubMed1991

Production of H2O2 by alveolar macrophages in experimental allergic alveolitis.

Experimental extrinsic allergic alveolitis (EAA) was induced in guinea pigs with Saccharopolyspora rectivirgula. Bronchoalveolar lavages were performed before inducing EAA (day 1, BAL 1), on day 23 (BAL 2), and on day 48 (BAL 3). The number of cells/ml in lavage fluid was increased at BAL 2 (4.79 x 10(6) and BAL 3 (4.29 x 10(6)) compared with BAL 1 (0.56 x 10(6)). The number of major cell types increased simultaneously, neutrophil becoming the predominant cell type over alveolar macrophages (AM). The production of H2O2 by AM was measured at the different phases of EAA. Adherent AM were either non-stimulated or triggered with phorbol myristate acetate (PMA), zymosan. S. rectivirgula opsonized with normal guinea pig serum (SRNS), or S. rectivirgula opsonized with guinea pig anti-S, rectivirgula serum (SRAS). Stimulated AM produced larger quantities of H2O2 than unstimulated cells, PMA being the most potent stimulus. At day 1, AM stimulated with S. rectivirgula and zymosan produced similar quantities of H2O2. After the induction of the disease, AM stimulated with S. rectivirgula produced larger quantities of H2O2 than with zymosan. Production of H2O2 by AM stimulated with S. rectivirgula or PMA, respectively, stayed the same at day 1 and 23, but increased sharply for both stimuli at day 48. There was no difference between H2O2 production by AM triggered with SRNS or with SRAS.(ABSTRACT TRUNCATED AT 250 WORDS)

Alveolitis, Extrinsic Allergic↗
PubMed1991

Epicardial and endocardial mapping of ventricular tachycardia in patients with myocardial infarction. Is the origin of the tachycardia always subendocardially localized?

BACKGROUND: Left ventricular endocardial reentry is the conventional concept underlying surgery for ventricular tachycardia (VT). We assessed the incidences of patterns showing complete reentry circuits at either the subendocardial or subepicardial level and of patterns in which left ventricular endocardial mapping could only in part account for a reentrant mechanism. METHODS AND RESULTS: We retrospectively analyzed epicardial and left ventricular endocardial isochronal maps of 47 VTs induced in 28 patients with chronic myocardial infarction (inferior, 14 patients; anteroseptal, 14 patients). Electrograms were recorded intraoperatively from 128 sites with epicardial sock and transatrial left ventricular endocardial balloon electrode arrays. Given the methodology used in this study, the mapping characteristics of the tachycardias suggested five types of activation patterns: 1) complete (90% or more of VT cycle length) subendocardial reentry circuits in seven VTs (15%) and seven patients (25%), 2) complete subepicardial reentry circuits in four VTs (9%) and four patients (14%), 3) incompletely mapped circuits with a left ventricular endocardial breakthrough preceding the epicardial breakthrough in 25 VTs (53%) and 21 patients (75%), 4) incompletely mapped circuits with a left ventricular epicardial breakthrough preceding the endocardial breakthrough in three VTs (6%) and three patients (11%), and 5) a right ventricular epicardial breakthrough preceding the left ventricular endocardial breakthrough in eight VTs (17%) and seven patients (25%). After surgery, one type 3 VT and three type 5 VTs were reinducible. Thus, left ventricular endocardial reentry substrates (types 1 and 3) accounted for 68% of VTs, but substrates involving subepicardial (types 2 and 4) and deep septal layers (type 5) accounted for 32% of VTs. CONCLUSIONS: In a substantial number of VTs, a substrate localization that is at variance with the conventional concept can be detected by simultaneous epicardial and endocardial mapping and may require modification of the surgical approach conventionally aimed at endocardial layers.

Cardiac Pacing, Artificial↗
PubMed1991

Respiratory health of workers exposed to swine confinement buildings only or to both swine confinement buildings and dairy barns.

Swine building workers (N = 488) and nonfarming neighborhood referents (N = 216) were enrolled in this study. There was a slight but significant increase in the prevalence of chronic bronchitis (17.49 versus 11.57%) and more evidence of airflow obstruction (forced expiratory volume in 1 s/forced vital capacity 0.75 versus 0.78) among the swine workers when they were compared with the referents. The subjects who spent more than 3 h/d in the swine buildings had a higher prevalence of chronic bronchitis (21.94 versus 13.25%) and airflow obstruction (forced expiratory volume in 1 s/forced vital capacity 0.75 versus 0.76) than those with shorter daily contact. Swine building only workers had no precipitins to antigens found in their environment and no clinical evidence of extrinsic allergic alveolitis. The number of years on the farm, dual exposure with dairy cattle, positive skin prick tests, type of piggery, and type of feeding did not add to the respiratory health impact of swine buildings.

Agricultural Workers' Diseases↗
PubMed1990

Surface immunoglobulin-positive lymphoblastic lymphoma. A report of three cases.

Lymphoblastic lymphomas (LBL) are a morphologically homogeneous group of non-Hodgkin's lymphomas which are indistinguishable in tissue sections from acute lymphoblastic leukemia (ALL). Although initial immunologic studies of LBL suggested that these lymphomas are of the T-cell phenotype, investigations have recently described patients with LBL having pre-B-cell, "common" ALL, and natural killer cell phenotypes. The authors recently reported detailed immunophenotypic characteristics in 36 cases of LBL, including a single case of LBL with a surface immunoglobulin-positive B-cell phenotype. Three additional patients with LBL whose cells expressed monoclonal serum immunoglobulins are presented here. In addition, the neoplastic lymphocytes expressed several B-cell-associated antigens. The tumor cells in the single case tested were TdT-negative. Despite the unusual immunologic phenotype, the morphologic features in all three cases were characteristic of LBL. In addition to the previously reported single case, to the authors' knowledge these are the only reported cases of a previously unrecognized variant of LBL: surface immunoglobulin-positive, B-cell LBL.

Adolescent↗
PubMed1990

Airborne microbial contents in two types of swine confinement buildings in Quebec.

Airborne microorganisms were isolated with a sampler in two types of swine confinement buildings (farrowing units and fattening units). Respirable (particles less than 5 microns) and total dust fractions were obtained. Samplings were repeated every 2 weeks for a total of 6 samplings per unit between January and April. The predominant microorganisms isolated were bacteria (up to 1.25 x 10(6) CFU/m3) with an important fraction in the respirable size range (up to 0.5 x 10(6) CFU/m3). Only small quantities of gram-negative bacteria, yeasts, and molds were found. Identification of the colonies isolated revealed a great diversity of microorganisms present in the air of the different buildings. Enterobacter agglomerans, Moraxella, Acinetobacter calcoaceticus, and Pseudomonas were the most frequently identified bacteria. Scopulariopsis, Aspergillus, Penicillium, and Candida were the most numerous fungi. Faenia rectivirgula, the causative agent of farmer's lung, was not a major contaminant. The results show some differences in airborne microbial contamination between farrowing and fattening units; the distinction, however, is not clear-cut and was observed only for the total bacteria. The level of airborne microbial contamination in swine units does not significantly vary as a function of the outside temperature. Some species of bacteria and fungi isolated in this study are known to induce extrinsic allergic alveolitis. Other fungi are known to be potentially pathogenic for man. The air of swine confinement buildings is highly contaminated with bacteria, yeasts, and molds at a level up to 1200 time higher than so-called "normal air."

Air Microbiology↗
PubMed1990

Sequential bronchoalveolar lavages by endotracheal intubation in guineapigs.

We examined the feasibility of performing repeated bronchoalveolar lavage (BAL) on guineapigs. We also determined the influence of lavage volume on cell recovery in these animals, verified if the free cell populations were altered by repeated lavage, and compared the results with those obtained after euthanasia. Live animals were intubated orotracheally by direct vision laryngoscopy and lavaged, except for the last BAL which was done on isolated lungs after euthanasia. Each animal was lavaged weekly for 8 weeks: weeks 1-5 lavages were done with 5 aliquots of 2 ml of normal saline, week 6 with 3 aliquots of 1 ml, week 7 with 3 aliquots of 2 ml, and week 8 with 5 aliquots of 2 ml after euthanasia. The first 5 BAL gave similar results in volumes recovered, total number of cells, cell viability and differentials. The total cell yield of lavages 6 and 7 was less than that of the first 5 BAL and BAL 8; cell differentials with these smaller lavages were similar except for the percentage of neutrophils which was slightly higher than with the 10 ml lavage at week 3. The final lavage gave similar results as the first 5 BAL in terms of total cells recovered, cell viability, and differentials. We conclude that repeated BAL is feasible in live guineapigs, and that it gives a similar cells yield as lung lavage obtained after euthanasia.

Animals↗
PubMed1989

Transgenic mice carrying the mouse mammary tumor virus ras fusion gene: distinct effects in various tissues.

Transgenic mice carrying the v-Ha-ras oncogene under the control of the mouse mammary tumor virus long terminal repeat were produced. These mice exhibit several phenotypes: mammary tumors, bilateral hyperplasia of the harderian lacrimal gland, primary bronchio-alveolar lung adenocarcinoma, and splenomegaly. High levels of the transgene RNA were detected in mammary, harderian, and lung tumors. Accumulation of cells of the myeloid lineages was found in enlarged spleens. This phenotype may represent an indirect effect of v-Ha-ras expression on myeloid progenitors. Our data illustrate the cell-specific effects of v-Ha-ras.

Animals↗
PubMed1979

[Early and late outcome after aortocoronary bypass: experience in 500 cases].

Between 1971 and 1976, 500 patients underwent aortocoronary bypass surgery. There were 15 operative deaths (3%) and the total frequency of perioperative infarction was 7%. The operative mortality was 7.4% in unstable angina, as compared with 1.1% in stable angina (P less than 0.01). The proportion of grafts patent at 2 weeks was 92% and at 18 months 87.6%. Postoperative follow-up was complete for 99% of the patients. There were 15 late deaths (3%) and the rates of survival at 2 and 4 years were 94.4% and 92.1% respectively. The actuarial curve of survival after surgery was not significantly different from that of the general population. After a mean follow-up of 27 months 73% of the patients were completely free of angina and 19% were markedly improved. The rate of recurrence of angina averaged 10% per year and the annual infarction rate was 0.7%. Fourteen patients (3%) underwent reoperation during the follow-up period. Thus, coronary revascularization surgery offers effective and sustained relief of incapacitating angina and might also improve survival if the operative mortality is low.

Adult↗
PubMed1979

Myofibroblasts in the stroma of invasive and metastatic carcinoma: a possible host response to neoplasia.

After observing the presence of numerous stromal myofibroblasts in scirrhous mammary carcinomas, a series of invasive and metastatic carcinomas from diverse sites was examined by electron microscopy to determine whether myofibroblasts might also be present in their stroma. Myofibroblasts were identified in each instance and were most abundant in neoplasms which were hard, sclerotic, and retracted. This finding suggests that myofibroblasts represent a component of the stromal reaction to many carcinomas and contribute to the desmoplasia and retraction which characterize many of these neoplasms. The host commands several responses to neoplasia. As a result of the expression of tumor-associated antigens, the immune system contributes lymphocytes, macrophages, and antibodies, a reflection of immunologic surveillance against neoplasia. In contrast to experimental systems tumor neoantigens are poorly expressed or even lacking in many human neoplasms; thus, the immune system may be weakly stimulated or not activated at all. Tumor neovascularization induced by a tumor-angiogenesis factor represents a second host response, possibly deleterious, for it may facilitate tumor dissemination. The stromal myofibroblast reaction to many invasive and metastatic carcinomas may constitute a third, albeit more primitive response. The density of collagen produced and contractile state of such tissue may signify an attempt by the host stroma to contain the neoplasm and impede vascular invasion. If so, myofibroblast induction may complement immune surveillance or constitute a separate mechanism of response to invasive neoplasia in man.

Carcinoma↗
PubMed1978

Dissociation between clinical and exercise responsiveness to beta-blockade in angina.

Twenty outpatients with mild angina were prescribed placebo tablets b.i.d. for 7 weeks followed by acebutolol, a cardioselective beta-blocker, 200 mg b.i.d. for 21 weeks under single-blind conditions. One graded multistage treadmill test was carried out after each treatment period and an angina diary was filled daily for the 6 months of the trial. Attack frequency declined by 71% from 2.59 per week on placebo to 0.76 per week on acebutolol (p less than 0.05). Exercise duration on the treadmill increased by 56%, from 5.95 minutes on placebo to 9.32 minutes on acebutolol (p less than 0.001). A satisfactory clinical response (50% or greater decline in attack frequency per week) occurred in 15 out of 19 patients (79%; a 100% or greater increase in exercise duration on the treadmill was observed in 10 out of 19 cases (53%). Exercise responsiveness was well predicted by exercise duration on placebo (r = 0.91, p less than 0.0005), patients with the least initial tolerance being the most improved. Clinical responsiveness was not well predicted by initial exercise tolerance (r = 0.38, N;S.) or by the improvement in exercise tolerance (r = 0.33, N.S.). It is concluded that acebutolol substantially reduces anginal attack frequency even in patients in whom exercise tolerance is not significantly improved, at the dose of 400 mg/day.

Acebutolol↗
PubMed1978

A new method for the precise and complete correction of distortion on cineangiographic image: its effect on left ventricular measurements.

Some of the problems associated with the precise evaluation of left ventricular volumes from angiographic images are due to the magnification and distortion of the pictures obtained from X-ray equipment. Magnification errors can be evaluated easily but the distortion (due to pincushion effect) are more difficult to measure. A mathematical method is proposed for a complete point-by-point correction of errors due to magnification and X-ray distortion. This method is applicable to most currently used angiographic equipment. Since more and more angiographic images are processed with local or remote digital computers, the applicability of the proposed technique becomes realistic. Results from this study show that a 5-30% overestimation of usual geometric ventricular parameters is encountered if no correction is made for distortion. End-diastolic measurements are more affected than end-systolic ones because of the greater degree of spherical distortion at the periphery of the picture area.

Cardiac Volume↗
PubMed1977

Elastosis in benign sclerosing ductal proliferation of the female breast.

Elastosis, an abundance of elastic tissue, is commonly present in breast carcinoma. However, its diagnostic significance remaines an unsettled issue. This study documents 17 cases of elastosis occurring in a distinctive benign sclerosing ductal lesion of the female breast (Fenoglio and Lattes: Cancer 33: 691-700, 1974). Elastosis was characterized by staining reactions and, in several instances, by elastase digestion and electron microscopy. Yellow streaks and flecks may be apparent grossly and probably reflect the increased elastic tissue. Histologically, the lesion is generally stellate with central sclerosis and marked peripheral intraductal and ductular hyperplasia which is often papillary. Elastosis, which may be marked, is a constant finding and is predominantly periductal in location. It is emphasized that the gross and histologic features of the lesion may mimic carcinoma and that elastosis may be found in benign ductal lesions of the breast.

Adult↗