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J Lavoie

Publications and source records attributed to J Lavoie.

At least 19 recordsLinked to original sources
PubMed2004

The development of experimental procedures for the evaluation of additives to attenuate manure odour, and the impact of these additives on workers, animals and the environment.

The objective of this project was to develop a laboratory research protocol to evaluate the effect of additives on manure odour and physico-chemical characteristics, and establish conditions that are representative of those found in farm storage structures (temperature, solids content, pH, ventilation above the manure surface, storage period). The results suggested that system configuration might have an impact on additive effect. An open system should be used when it is recommended that additives be applied in the animal diet or the gutters. Additionally, the surface/depth ratio of the gutter should be respected, since it will impact on the relative importance of the aerobic layer and on ammonia volatilization. On the other hand, a closed system should be used when the additive is applied to the manure storage tank, especially if the tank has a cover. Odour analysis still requires fundamental research to establish reliable procedures and protocols, especially in the area sample collection and dilution levels required to decrease H2S concentration to safe levels for the panellists. Odour analysis should also be conducted in triplicate, because of the possible large experimental error due to dilution, the human factors, and also instrumental error.

Ammonia↗
PubMed2003

Stem cell transplantation for myelofibrosis: a report from two Canadian centers.

We describe the course of 25 patients with myelofibrosis (MF) due to agnogenic myeloid metaplasia (n=19) or essential thrombocytosis (n=6) who underwent allogeneic stem cell transplantation (SCT) at one of two Canadian centers. The median age at transplantation was 48.7 (IQR 45.9-50.4) years and transplantation was carried out at a median of 10.7 (IQR 5.67-26.5) months after diagnosis. Granulocyte engraftment (absolute neutrophil count >0.5 x 109/l) occurred at a median of 20 days after transplantation for splenectomized patients, compared with 27.5 days for nonsplenectomized individuals (P=0.03). Increased risk of grade II-IV acute graft-versus-host disease (P=0.04) was noted in patients transplanted after splenectomy. Patients with MF received 0.264+/-0.189 U of packed red blood cells per day over the first 180 days after transplantation, and remained dependent on red blood cell transfusions for a median of 123 (IQR 48-205) days. Complete remission of MF was documented in 33% of evaluable patients. The 1 year cumulative nonrelapse mortality was 48.3%. Median survival for this group of patients was 393 (IQR 109-1014+) days, with a projected 2-year overall survival of 41%. We conclude that allogeneic SCT offers a reasonable chance for prolonged survival in patients with advanced MF, but this occurs at the cost of considerable toxicity and nonrelapse mortality.

Erythrocyte Transfusion↗
PubMed2002

Treatment of lymphoid malignancies with non-myeloablative stem cell transplantation.

The traditional approach to allogeneic hematopoietic stem cell transplantation involves the administration of myeloablative preparative regimens. This form of conditioning is associated with a relatively high incidence of regimen-related toxicity. As a result, candidates for allogeneic stem cell transplantation may be excluded owing to advanced age or co-morbid medical illness. Recently, so-called "non-myeloablative" regimens have been introduced, where less intense conditioning therapy is used in an attempt to reduce regimen-related toxicity. In addition, non-myeloablative transplantation takes advantage of the graft-versus-tumour effect that is characteristic of allogeneic stem cell transplantation. We review the background, available clinical data, and future directions in non-myeloablative stem cell transplantation, and focus on its potential use in the treatment of lymphoid malignancies.

Graft vs Tumor Effect↗
PubMed2001

Lymphoblasts already in the DNA synthesis phase of the cell cycle can be reversibly arrested at the R/G transition.

Early and late S-phase of the cell cycle are separated by the R-band/G-band (R/G) transition. This corresponds to the time at which R-band synthesis has been completed while G-band synthesis has yet to begin. The aim of this work was to study cell cycle kinetics during S-phase using different blocking agents: mimosine, methotrexate, 5-fluorouracil, 5-fluoro-2'-deoxyuridine and an excess of thymidine. The stage at which these blocking agents arrest the cell cycle and their efficiency at blocking Epstein-Barr virus transformed lymphoblasts at the R/G transition were evaluated using flow cytometric techniques. Mimosine blocked 90% of the cells near the G1/S-phase boundary. Methotrexate, 5-fluoro-2'-deoxyuridine and 5-fluorouracil, and particularly thymidine, let a significant proportion of cells enter S-phase. The cells were released from the arrest state and their progression through early S-phase was monitored by flow cytometry. Before the cells reached the R/G transition, a second agent was added to inhibit cell cycle progression. For example, the use of mimosine followed by thymidine allowed up to 60% of the cells to be blocked at the R/G transition. The arrest of DNA replication at the R/G transition was confirmed by a marked decrease of 5-bromo-2'-deoxyuridine (BrdUrd) incorporation, revealed by using bivariate flow cytometric analysis. The blocking agent was then removed and the cell cohort was released in the presence of BrdUrd so that replication banding analysis could be performed on the harvested mitotic cells. This yielded a mitotic index of approximately 10% and chromosomes showing replication bands. Flow cytometric analysis combined with cytogenetic banding analysis suggested that the R/G transition is an arrest point within the S-phase of the cell cycle and allowed us to conclude that only cells that have already initiated S-phase are blocked at this point. It corresponds to a susceptible site where S-phase can be arrested easily. The R/G transition could also be a regulatory checkpoint within S-phase, a checkpoint that could respond to imbalance in deoxyribonucleotide pools.

Bromodeoxyuridine↗
PubMed2001

Neonatal aortic arch reconstruction avoiding circulatory arrest and direct arch vessel cannulation.

BACKGROUND: Aortic arch reconstruction in neonates routinely requires deep hypothermic circulatory arrest. We reviewed our experience with techniques of continuous low-flow cerebral perfusion (LFCP) avoiding direct arch vessel cannulation. METHODS: Eighteen patients, with a median age of 11 days (range 1 to 85 days) and a mean weight of 3.2 +/- 0.8 kg, underwent aortic arch reconstruction with LFCP. Seven had biventricular repairs with arch reconstruction, 9 underwent the Norwood operation and 2 had isolated arch repairs. In 1 Norwood and 7 biventricular repair patients, LFCP was maintained by advancing the cannula from the distal ascending aorta into the innominate artery. In 8 of 9 Norwood patients, LFCP was maintained by directing the arterial cannula into the pulmonary artery confluence and perfusing the innominate artery through the right modified Blalock-Taussig shunt fully constructed before cannulation for cardiopulmonary bypass. In 2 patients requiring isolated arch reconstruction, the ascending aorta was cannulated and the cross-clamp was applied just distal to the innominate artery. RESULTS: LFCP was maintained at 0.6 +/- 0.2 L x min(-1) x m(-2) for 41.0 +/- 13.9 minutes at 18.5 degrees C +/- 1.1 degrees C. In 10 of the 18 patients, blood pressure during LFCP was 15 +/- 8 mm Hg remote from the innominate artery (left radial, umbilical or femoral arteries). In 8 of the 18 patients, right radial pressure during LFCP was 24 +/- 10 mm Hg. The mean mixed-venous saturation was 79.8% +/- 10% during LFCP. Two patients had preoperative seizures, whereas none had seizures postoperatively. One patient died. CONCLUSIONS: Neonatal aortic arch reconstruction is possible without circulatory arrest or direct arch vessel cannulation. These techniques maintained adequate mixed-venous oxygen saturations with no associated adverse neurologic outcomes.

Aorta, Thoracic↗
PubMed2001

Systemic steroid pretreatment improves cerebral protection after circulatory arrest.

BACKGROUND: This study evaluates whether systemic steroid pretreatment enhances neuroprotection during deep hypothermic circulatory arrest (DHCA) compared with steroid in cardiopulmonary bypass (CPB) prime. METHODS: Four-week-old piglets randomly placed into two groups (n = 5 per group) were given methylprednisolone (30 mg/kg) into the pump prime (group PP), or pretreated intravenously 4 hours before CPB (group PT). All animals underwent 100 minutes of DHCA (15 degrees C), were weaned off CPB, and were sacrificed 6 hours later. Postoperative changes in body weight, bioimpedance, and colloid oncotic pressure (COP) were measured. Cerebral trypan blue content, immunohistochemical evaluation of transforming growth factor-beta1 (TGF-beta1) expression, and caspase-3 activity were performed. RESULTS: Percentage weight gain (group PP 25.0% +/- 10.4% versus group PT 12.5% +/- 4.0%; p = 0.036), and percentage decrease in bioimpedance (PP 37.2% +/- 14.5% versus PT 15.6% +/- 7.9%; p = 0.019) were significantly lower, whereas postoperative COP was significantly higher in group PT versus group PP (PT 15.3 +/- 1.8 mm Hg versus PP 11.6 +/- 0.8 mm Hg; p = 0.003). Cerebral trypan blue (ng/g dry tissue) was significantly lower in group PT (PT 5.6 x 10(-3) +/- 1.1 x 10(-3) versus PP 9.1 x 10(-3) +/- 5.7 x 10(-4); p = 0.001). Increased TGF-beta1 expression and decreased caspase-3 activity were shown in group PT. CONCLUSIONS: Systemic steroid pretreatment significantly reduced total body edema and cerebral vascular leak and was associated with better immunohistochemical indices of neuroprotection after DHCA.

Animals↗
PubMed2001

Evaluation of health and safety risks in municipal solid waste recycling plants.

Designers and managers of recycling processing plants need to be informed about the inherent occupational health and safety risks; however, there are few studies in the literature describing these risks. Therefore, the objectives of this project were to document the biological, chemical, physical, and ergonomic risks in three household-waste recycling plants. Bioaerosols (molds and bacteria) were measured using the methodology recommended by the American Society for Testing and Materials (ASTM). Chemical contaminants and physical agents suspected of being present in this type of environment were measured using the standard methods of the Quebec Occupational Health and Safety Research Institute (IRSST). The ergonomic part of the study identified the work requirements and risk factors causing the workers' physical symptoms. In summer, the average concentrations of total bacteria were greater than the Scandinavian guideline of 10,000 colony forming units per cubic meter of air (CFU/m3) in the receiving areas in plants 1 and 3, in the sorting areas of the three plants, and in shipping in plants 1 and 3. When the average concentrations of gram-negative bacteria were compared to the Scandinavian guideline of 1000 CFU/m3 of air, only the sorting department in plant 2 in summer exceeded this value. Average indoor concentrations of molds that were statistically significantly greater than those measured in the upwind outdoor air were measured in all departments in plants 1 and 3, regardless of the season, and only in sorting in plant 2 during the summer. The only chemical contaminant measured at average concentrations greater than 50% of the Threshold Limit Values (TLVs) proposed by the American Conference of Governmental Industrial Hygienists (ACGIH) was CO in the sorting departments in plants 1 and 2 during the winter. Noise exceeded the ACGIH TLV in plant 2. The workers' physical symptoms seem to be caused by the posture and effort required while remaining in a stationary position. Action must be focused on improving aspects such as work organization and personal protection and on informing citizens of the need for cleanliness of the material to be recycled.

Accidents, Occupational↗
PubMed2001

TGF-beta(1) and prepro-ANP mRNAs are differentially regulated in exercise-induced cardiac hypertrophy.

The induction of transforming growth factor (TGF)-beta and prepro-atrial natriuretic peptide (ANP) mRNAs represent hallmark features of pathological cardiac hypertrophy. The present study examined whether this pattern of mRNA expression was conserved in a physiological model of cardiac hypertrophy. To address this thesis, female Sprague-Dawley rats were individually housed and permitted to run freely. Voluntary exercise for 3 and 6 wk resulted in biventricular hypertrophy and increased cytochrome c oxidase activity in the triceps muscle. In the hypertrophied left ventricle, the steady-state mRNA level of the cardiac fetal gene prepro-ANP and the extracellular matrix proteins preprocollagen-alpha(1) and fibronectin were similar in exercise-trained and sedentary rats. By contrast, an increased expression of TGF-beta(1) mRNA was observed, whereas TGF-beta(3) mRNA level was unchanged in the hypertrophied left ventricle of exercise-trained compared with sedentary rats. These data highlight a heterogeneity in the regulation of TGF-beta isoforms, and the increased expression of ventricular TGF-beta(1) mRNA in physiological cardiac hypertrophy may contribute to myocardial remodeling.

Animals↗
PubMed2000

Establishment and characterization of a new cell line derived from a human primary breast carcinoma.

A new cell line, designated HDQ-P1, was successfully established from a primary ductal infiltrating mammary carcinoma by using a 3T3 feeder layer lethally irradiated to 60 Gy. The HDQ-P1 cells have been grown in culture for over 115 passages and have a doubling time of 60 hours. Characterization of the cell line was performed. This included morphology by light and transmission electron microscopy, karyotype, growth rate, telomerase expression, tumor antigen expression, xenograft implantation into nude mice, colony formation in soft agar, TP53 sequencing, and gene copy number of C-MYC, C-ERBB-2, and C-H-RAS oncogenes. The epithelial nature of this cell line was confirmed by ultrastructural analysis, expression of cytokeratins, and epithelial membrane antigen. The HDQ-P1 cells possess an extensively rearranged and polyploid karyotype, with an average of 20 recurrent marker chromosomes. Scatchard analysis demonstrated that both primary tumor and HDQ-P1 cells were estrogen- and progesterone-receptor negative. The HDQ-P1 cells had the same expression of human telomerase reverse transcriptase as other established breast cancer cell lines such as MDA-MB-231, SK-BR-3, and MCF-7. Direct DNA sequencing showed a point mutation which yielded to a stop codon at the amino acid 213 in exon 6 of the TP53 gene. A five-fold amplification of C-MYC was observed in HDQ-P1 cells. No amplification of C-ERBB-2 and C-H-RAS genes were observed. This cell line presents unique characteristics and may prove to be a good experimental model for investigating breast cancer biology.

Animals↗
PubMed1999

Physiological and cytogenetic characterization of immortalized human endometriotic cells containing episomal simian virus 40 DNA.

The study of misplaced endometrial cells, which abnormally implant and grow outside the uterine cavity, is of considerable interest for the understanding of the pathophysiology of endometriosis. However, endometriotic cells, particularly epithelial cells, required for primary cell culture are not easily available. We report here the characterization of an endometriotic cell line immortalized after infection of primary endometriotic cell cultures with simian virus 40. Transformed cells express T-antigen, and blot hybridization analysis showed that the viral genome is present as an episome. Cytogenetic analysis revealed a polyploid karyotype with numerical and structural rearrangements involving mainly the same chromosomes (6, 10, 11, 15, and 17). The cell line has been maintained in culture for over 80 passages and was still proliferating without any noticeable change in the biological properties investigated. Transformed endometriotic cells expressed both progesterone and estradiol receptors and were stimulated by these ovarian hormones to secrete monocyte chemotactic protein-1, a factor that may play an important role in the recruitment and activation of peritoneal macrophages. In addition, this response was enhanced in interleukin-1-treated cells. Taken together, these findings support the view that this cell line may be an interesting tool for the study of the pathophysiology of endometriosis.

Adult↗
PubMed1998

Decreased survival in rat liver transplantation with extended cold preservation: role of portal vein clamping time.

Primary liver graft dysfunction is currently related to cold ischemia-reperfusion injury, although a wide survival range has been reported using 24-hour preservation in cold University of Wisconsin (UW) solution. We hypothesized that the portal vein clamping time (PVCT) played a more important role than cold preservation injury in the postoperative outcome. Rat liver transplantation was performed using different clamping times after 24-hour cold ischemia in the UW solution. Survival rates, plasma tumor necrosis factor (TNF), and nitrate/nitrite levels were examined. Subsequently, the effect of clamping time was evaluated on hepatocyte and sinusoidal endothelial cell (SEC) function using isolated perfused livers. Survival rate was directly related to clamping time length. Marked increases in TNF and nitrate/nitrite levels were found after surgery, particularly after long clamping times. In perfusion studies, the SEC function was already markedly altered after preservation alone and was not further modified by transplantation. By contrast, the hepatocyte function was moderately altered after transplantation, irrespective of clamping times, even when rats operated with long clamping times were in terminal conditions. In rats, 24-hour preservation in cold UW solution is not a severely compromising condition leading to primary liver nonfunction. Long PVCTs are associated with an endotoxemia-like syndrome more related to a warm intestinal ischemia than to cold ischemia injury of the liver.

Animals↗
PubMed1998

TEE monitoring.

Explore the source record for details and available documents.

Adult↗
PubMed1998

Plasma and CSF benzodiazepine receptor ligand concentrations in cirrhotic patients with hepatic encephalopathy: relationship to severity of encephalopathy and to pharmaceutical benzodiazepine intake.

Increased plasma and CSF concentrations of substances which bind to brain benzodiazepine receptors have previously been reported in cirrhotic patients with hepatic encephalopathy (HE). However, their relationship to previous intake of pharmaceutical benzodiazepines has not been clearly established. In the present study, plasma levels of benzodiazepine receptor ligands (BZRLs) were measured using a sensitive radioreceptor assay in 12 control subjects with no evidence of hepatic, neurological or psychiatric illness, 11 cirrhotic patients without HE, 24 cirrhotic patients with moderate (grade I-II) HE and in 45 cirrhotic patients with severe (grade II-IV) HE. In addition, CSF concentrations of BZRLs were measured in 8 cirrhotic patients with HE and an equal number of age-matched controls. Recent intake (within 10 days) of pharmaceutical benzodiazepines was assessed by detailed review of medical files, and interviews with the patient, at least one family member as well as the pharmacist. Significantly increased plasma concentrations of BZRLs were observed in cirrhotic patients with severe encephalopathy (p < 0.02) compared to controls and to cirrhotic patients without (or with mild) neurological impairment. Increased plasma BZRLs could be accounted for by prior exposure to benzodiazepine medication in all cases. CSF concentrations of BZRLs in cirrhotic patients were not significantly different from control values. These findings do not support a role for "endogenous" benzodiazepines in the pathogenesis of HE in chronic liver disease but suggest that pharmaceutic benzodiazepines administered to cirrhotic patients as sedatives or as part of endoscopic work-up could have contributed to the neurological impairment in some patients.

Animals↗
PubMed1997

Two-dimensional gel electrophoresis analysis of endovacuolar organelles.

Cells perform their multiple functions with the aid of a series of distinct membrane organelles. In the last years, many of these compartments have been isolated, purified, and extensively studied. The major roles of each organelle in the cell are well understood. However, most of the molecular basis by which they perform their functions is poorly known. The recent identification and study of a handful of proteins associated with endovacuolar compartments has had a major impact on the understanding of the molecular details of organelle functions even though two-dimensional (2-D) gel analysis indicates that hundreds of proteins are typically associated with a complex organelle. This shows that many details and surprises are still to come for cell biologists. In the present study, we have analyzed and compared different organelles of the endocytic and phagocytic apparatus using 2-D gel electrophoresis.

Animals↗
PubMed1996

Alterations of thiamine phosphorylation and of thiamine-dependent enzymes in Alzheimer's disease.

There is a growing body of evidence to suggest that thiamine neurochemistry is disrupted in Alzheimer's Disease (AD). Studies in autopsied brain tissue from neuropathologically proven AD patients reveal significantly reduced activities of the thiamine phosphate dephosphorylating enzymes thiamine diphosphatase (TDPase) and thiamine monophosphatase (TMPase) as well as the thiamine diphosphate-dependent enzymes, pyruvate dehydrogenase complex, alpha-ketoglutarate dehydrogenase (alpha KGDH) and transketolase. Reductions in enzyme activities are present both in affected areas of AD brain as well as in relatively well conserved tissue. Decreased TDP concentrations and concomitantly increased TMP in autopsied brain tissue from AD patients and in CSF from patients with Dementia of the Alzheimer Type suggests that CNS thiamine phosphorylation-dephosphorylation mechanisms are disrupted in AD. alpha KGDH is a rate-limiting enzyme for cerebral glucose utilization and decreases in its activity are associated with lactic acidosis, cerebral energy failure and neuronal cell loss. Deficiencies of TDP-related metabolic processes could therefore participate in neuronal cell death mechanisms in AD.

Alzheimer Disease↗
PubMed1996

Video-assisted thoracoscopic surgery for the treatment of congenital cardiac defects in the pediatric population.

Recent technologic advances have contributed to a renewed interest in thoracoscopic surgery. In our institution, thoracoscopy through video-assisted technology has been successfully applied to congenital heart surgery. We reviewed the charts of 45 consecutive patients (ASA physical status 11-IV) who underwent video-assisted thoracoscopic surgery (VATS) for various congenital heart defects. The mean age of the patients was 2.65 yr and the mean weight was 11.78 kg. The surgical procedures included patent ductus arteriosus interruption (n = 28) and vascular ring division (n = 8), and 9 patients had miscellaneous procedures. The most commonly used anesthetic regimen consisted of isoflurane, pancuronium, fentanyl, air, and oxygen. Seven patients were managed with one-lung ventilation, the remainder by two-lung ventilation with surgical lung retraction. Intraoperative desaturation occurred in 12 patients (26.7%) but resolved quickly with brief reexpansion of the lungs. Postoperative complications included: pleural effusions (n = 3), chylothorax (n = 2), right upper lobe atelectasis (n = 1), small pneumothorax (n = 1), and vocal cord paralysis (n = 1). Seven patients (15.5%) required conversion to a thoracotomy for insufficient exposure (n = 4) or due to concern over bleeding (n = 3). This experience with VATS in pediatric patients with congenital heart disease may provide a database for comparison with others who work with the VATS technique.

Adolescent↗
PubMed1995

Loss of [3H]kainate and of NMDA-displaceable [3H]glutamate binding sites in brain in thiamine deficiency: results of a quantitative autoradiographic study.

Previous studies suggest that alterations of brain glutamate synthesis and release occur in experimental thiamine deficiency. In order to assess the integrity of post-synaptic glutamatergic receptors in thiamine deficiency, binding sites for [3H]glutamate (displaced by NMDA), [3H]-kainate, and [3H]quisqualate (AMPA sites) were evaluated using Quantitative Receptor Autoradiography in rat brain following 14 days of treatment with the central thiamine antagonist pyrithiamine. Compared to pair-fed controls, brains of symptomatic thiamine-deficient animals contained significantly fewer NMDA-displaceable binding sites in cerebral cortex, medial septum and hippocampus. It has been suggested that NMDA-receptor mediated glutamate excitotoxicity plays a role in the pathogenesis of neuronal loss in thiamine deficiency. If such is the case, the selective loss of NMDA binding sites in cerebral cortex and hippocampus offers a possible explanation for the relative nonvulnerability of these brain regions to pyrithiamine-induced thiamine deficiency. [3H]quisqualate (AMPA) binding sites were unchanged in all brain regions of pyrithiamine-treated rats whereas [3H]kainate sites were significantly reduced in density in medial and lateral thalamus. The decline in these binding sites may be due to neuronal loss in pyrithiamine-induced thiamine deficiency. Alterations of glutamatergic synaptic function involving both NMDA and kainate receptor subclasses could contribute to the pathogenesis of neurological dysfunction in Wernicke's Encephalopathy in humans.

Animals↗