Cegep de Sainte Foy

BACKGROUND: IL-17 is a cytokine that has been reported to be produced by T lymphocytes. In vitro, IL-17 activates fibro-blasts and macrophages for the secretion of GM-CSF, TNF-alpha, IL-1beta, and IL-6. A number of these cytokines are involved in the airway remodeling that is observed within the lungs of asthmatic individuals. OBJECTIVE: In this study, we investigated the expression of IL-17 in sputum and bronchoalveolar lavage specimens obtained from asthmatic subjects and from nonasthmatic control subjects. METHODS: IL-17 was detected through use of immunocytochemistry, in situ hybridization, and Western blot. Bronchial fibroblasts were stimulated with IL-17, and cytokine production and chemokine production were detected through use of ELISA and RT-PCR. RESULTS: Using immunocytochemistry, we demonstrated that the numbers of cells positive for IL-17 are significantly increased in sputum and bronchoalveolar lavage fluids of subjects with asthma in comparison with control subjects (P <.001 and P <.005, respectively). We demonstrated that in addition to T cells, eosinophils in sputum and bronchoalveolar lavage fluids expressed IL-17. Peripheral blood eosinophils were also positive for IL-17, and the level of IL-17 in eosinophils purified from peripheral blood was significantly higher in subjects with asthma than in controls (P <.01). To further investigate the mechanism of action of IL-17 in vivo, we examined the effect of this cytokine on fibroblasts isolated from bronchial biopsies of asthmatic and nonasthmatic subjects. IL-17 did enhance the production of pro-fibrotic cytokines (IL-6 and IL-11) by fibroblasts, and this was inhibited by dexamethasone. Similarly, IL-17 increased the level of other fibroblast-derived inflammatory mediators, such as the alpha-chemokines, IL-8, and growth-related oncogene-alpha. CONCLUSION: Our results, which demonstrate for the first time that eosinophils are a potential source of IL-17 within asthmatic airways, suggest that IL-17 might have the potential to amplify inflammatory responses through the release of proinflammatory mediators such as alpha-chemokines.

Editorial by Little and Byrne It is generally accepted that obesity is a health hazard because of its association with numerous metabolic complications such as dyslipidaemia, type 2 diabetes, and cardiovascular diseases.1 On that basis, health agencies 2 3 have proposed that obesity should be defined on the basis of weight in kg expressed over height in m2, the so called body mass index,4 initially described by Quetelet in 1869 (table). Epidemiological studies have reported a progressive increase in the incidence of chronic diseases such as hypertension, diabetes, and coronary heart disease with increasing body mass index.1-3 However, despite this well documented evidence, physicians are, in their daily practice, perplexed by the remarkable heterogeneity found in their obese patients. For instance, some patients show a relatively “normal” profile of metabolic risk factors despite the presence of substantial excess body fat, whereas others who are only moderately overweight can nevertheless be characterised by a whole cluster of metabolic complications, increasing the risk of type 2 diabetes, coronary atherosclerosis, and cardiovascular disease. View this table: Classification of obesity based on body mass index (BMI)2 3 #### Summary points A simple measurement such as waist circumference can indicate accumulation of abdominal fat Viscerally obese men are characterised by an atherogenic plasma lipoprotein profile A triad of non-traditional markers for coronary heart disease found in viscerally obese middle aged men (hyperinsulinaemia, raised apolipoprotein B concentration, and small LDL particles) increases the risk of coronary heart disease 20-fold Four out of five middle aged men with a waist measurement ≥90 cm and triglyceride concentrations ≥2 mmol/l are characterised by this triad Even in the absence of hypercholesterolaemia, hyperglycaemia, or hypertension, obese patients could be at high risk of coronary heart disease if they have this “hypertriglyceridaemic waist” phenotype In this regard, epidemiological and metabolic studies …

Obesity is becoming a global epidemic in both children and adults, and it is associated with numerous co-morbidities such as cardiovascular diseases (CVD), type 2 diabetes, hypertension, certain cancers, and sleep apnea/sleep-disordered breathing. In fact, is an independent risk factor for CVD and CVD risks have been also documented in obese children, and is associated with reduced life expectancy. A variety of adaptations/alterations in cardiac structure and function occur in the individual as adipose tissue accumulates in excess amount. As a whole, overweight/obesity predispose or is associated with numerous cardiac complications such as coronary heart disease, heart failure, and sudden death through its impact on the cardiovascular system.

OBJECTIVE: Because a pseudonormal pattern of ventricular filling has never been considered in studies that reported a prevalence of left ventricular diastolic dysfunction (LVDD) between 20 and 40%, our aim was to more completely evaluate the prevalence of LVDD in subjects with diabetes. RESEARCH DESIGN AND METHODS: We studied 46 men with type 2 diabetes who were aged 38-67 years; without evidence of diabetic complications, hypertension, coronary artery disease, congestive heart failure, or thyroid or overt renal disease; and with a maximal treadmill exercise test showing no ischemia. LVDD was evaluated by Doppler echocardiography, which included the use of the Valsalva maneuver and pulmonary venous recordings to unmask a pseudonormal pattern of left ventricular filling. RESULTS: LVDD was found in 28 subjects (60%), of whom 13 (28%) had a pseudonormal pattern of ventricular filling and 15 (32%) had impaired relaxation. Systolic function was normal in all subjects, and there was no correlation between LVDD and indexes of metabolic control. CONCLUSIONS: LVDD is much more common than previously reported in subjects with well-controlled type 2 diabetes who are free of clinically detectable heart disease. The high prevalence of this phenomenon in this high-risk population suggests that screening for LVDD in type 2 diabetes should include procedures such as the Valsalva maneuver and pulmonary venous recordings to unmask a pseudonormal pattern of ventricular filling.

BACKGROUND: The widespread application of pulmonary rehabilitation in chronic obstructive pulmonary disease (COPD) should be preceded by demonstrable improvements in function attributable to the programs. This review updates that reported in 2001. OBJECTIVES: To determine the impact of rehabilitation on health-related quality of life (QoL) and exercise capacity in patients with COPD. SEARCH STRATEGY: We identified additional RCTs from the Cochrane Airways Group Specialised Register. Searches were current as of July 2004. SELECTION CRITERIA: We selected RCTs of rehabilitation in patients with COPD in which quality of life (QoL) and/or functional (FEC) or maximal (MEC) exercise capacity were measured. Rehabilitation was defined as exercise training for at least four weeks with or without education and/or psychological support. Control groups received conventional community care without rehabilitation. DATA COLLECTION AND ANALYSIS: We calculated weighted mean differences (WMD) using a random-effects model. We requested missing data from the authors of the primary study. MAIN RESULTS: We included the 23 randomized controlled trials (RCTs) in the 2001 Cochrane review. Eight additional RCTs (for a total of 31) met the inclusion criteria. We found statistically significant improvements for all the outcomes. In four important domains of QoL (Chronic Respiratory Questionnaire scores for Dyspnea, Fatigue, Emotional function and Mastery), the effect was larger than the minimal clinically important difference of 0.5 units (for example: Dyspnoea score: WMD 1.0 units; 95% confidence interval: 0.8 to 1.3 units; n = 12 trials). Statistically significant improvements were noted in two of the three domains of the St. Georges Respiratory Questionnaire. For FEC and MEC, the effect was small and slightly below the threshold of clinical significance for the six-minute walking distance (WMD: 48 meters; 95% CI: 32 to 65; n = 16 trials). AUTHORS' CONCLUSIONS: Rehabilitation relieves dyspnea and fatigue, improves emotional function and enhances patients' sense of control over their condition. These improvements are moderately large and clinically significant. Rehabilitation forms an important component of the management of COPD.

BACKGROUND: Total cholesterol (TC)/high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C)/HDL-C ratios are used to predict ischemic heart disease risk. There is, however, no consensus on which of these 2 indices is superior. The objective of the present study was to present evidence that the LDL-C/HDL-C ratio may underestimate ischemic heart disease risk in overweight hyperinsulinemic patients with high triglyceride (TG)-low HDL-C dyslipidemia. METHODS: A total of 2103 middle-aged men in whom measurements of the metabolic profile were performed in the fasting state were recruited from 7 suburbs of the Quebec metropolitan area. RESULTS: The relationship of LDL-C/HDL-C to TC/HDL-C ratios was examined among men in the Quebec Cardiovascular Study classified into tertiles of fasting TG levels. For any given LDL-C/HDL-C ratio, the TC/HDL-C ratio was higher among men in the top TG tertile (>168 mg/dL [>1.9 mmol/L]) than in men in the first and second TG tertiles. Adjustment of the TC/HDL-C ratio for LDL-C/HDL-C by covariance analysis generated significant differences in average TC/HDL-C ratios among TG tertiles (P<.001). Greater differences in features of the insulin resistance syndrome (insulinemia, apolipoprotein B, and LDL size) were noted across tertiles of the TC/HDL-C ratio than tertiles of the LDL-C/HDL-C ratio. CONCLUSION: Variation in the TC/HDL-C ratio may be associated with more substantial alterations in metabolic indices predictive of ischemic heart disease risk and related to the insulin resistance syndrome than variation in the LDL-C/HDL-C ratio.

Regional fat distribution is an important determinant of insulin resistance in obesity. In the current study, the relationship between skeletal muscle insulin sensitivity, mid‐thigh muscle composition, and the metabolic profile of muscle was investigated. Muscle composition was assessed by computed tomography of the mid‐thigh, and by activities of marker enzymes of aerobic‐oxidative and glycolytic pathways and muscle fiber typing using biopsies of the vastus lateralis muscle. Muscle with reduced Hounsfield attenuation on computed tomography scans was increased in proportion to obesity, and was strongly related to insulin resistance, reduced muscle oxidative capacity, and increased anaerobic and glycolytic capacities by muscle. These findings suggest that as part of its expression of insulin resistance, skeletal muscle of obese individuals is also poorly equipped for substrate oxidation and manifests increased storage of fat.—Simoneau, J.‐A., Colberg, S. R., Thaete, F. L., Kelley, D. E. Skeletal muscle glycolytic and oxidative enzyme capacities are determinants of insulin sensitivity and muscle composition in obese women. FASEB J. 9, 273–278 (1995)

Numerous studies have shown that a high accumulation of abdominal fat is associated with metabolic complications and with an increased risk of coronary heart disease. The present study examined the effects of changes in body fatness and in the level of abdominal fat on metabolic variables in a sample of 13 obese premenopausal women, aged 38.8 +/- 5.3 (SD) yr. Women exercised for 90 min at approximately 55% of maximal aerobic power (VO2 max) four to five times a week for a period of 14 mo. The training program induced a significant increase in VO2 max and a mean reduction in body fat mass of 4.6 kg (P less than 0.01), with no change in fat-free mass. Measurement of adipose tissue areas by computed tomography indicated a greater loss of abdominal fat compared with midthigh adipose tissue (P less than 0.05). The training program also produced significant reductions in the insulinogenic index measured during an oral glucose tolerance test and in plasma cholesterol (Chol), low-density lipoprotein (LDL)-Chol, and apolipoprotein (apo) B levels (P less than 0.05). Training also significantly increased plasma high-density lipoprotein (HDL)-apo A-I and HDL2-Chol levels and decreased plasma HDL3-Chol concentration (P less than 0.05). Whereas no change in postheparin plasma lipoprotein lipase activity was noted, a significant decrease in postheparin plasma hepatic triglyceride lipase activity was observed after training (P less than 0.005). Metabolic responses were not correlated with changes in VO2 max but were significantly correlated with the reduction in body fat mass and/or with the loss of deep abdominal fat.(ABSTRACT TRUNCATED AT 250 WORDS)

Dopamine and it metabolites dihydroxyphenylacetic acid and homovanillic acid were measured in the retinas of eight patients with Parkinson's disease who died. They were divided into two groups according to their last dose of levodopa therapy. One group of three patients had not received levodopa therapy for at least 5 days before death, and the other group of five patients had received therapy 2-15 hours before death. Each patient was matched with controls for delay between death and freezing. In the three patients without levodopa therapy, the retinal dopamine content was lower than normal. In the five patients who received levodopa therapy before death, the retinal dopamine content was similar to that in the controls. This study is the first direct evidence to the authors' knowledge that retinal dopamine concentration is decreased in Parkinson's disease, as it is in the nigrostriatal pathway.

Although metabolic disturbances are often observed in obese patients, increased accumulation of visceral adipose tissue (AT) has been shown to be more closely associated with high fasting triglyceride (TG) and insulin levels as well as with low HDL cholesterol concentrations than with excess body fatness per se. Interestingly, the fasting concentration of plasma TGs has been shown to be an important determinant of the magnitude and duration of the postprandial TG response. Yet little is known about the respective contributions of obesity versus excess visceral AT to the variation in postprandial TG clearance. In the present study, we examined potential differences in postprandial triglyceride-rich lipoprotein (TRL) responses in subjects characterized by high versus low levels of visceral AT. In a sample of 43 men (mean age: 41.3 +/- 9.6 years), we found that both excess body fat and visceral obesity were associated with increased postprandial TG responses in total TRL (r = 0.33-0.45). We also found a strong relationship between fasting plasma TG levels and postprandial total TRL-TG concentrations (r = 0.79, P < 0.0001). When matched for total body fat mass, individuals with high levels of visceral AT (> or =130 cm2; n = 10) as assessed by computed tomography were characterized by increased medium- and small-TRL-TG responses (P < 0.05) compared with subjects with low visceral AT accumulation (<130 cm2; n = 10). Moreover, this elevated response of small-TRL triglycerides noted in men with high levels of visceral AT was not accompanied by a concomitant increased retinyl palmitate response in this TRL fraction, suggesting that visceral obesity in men is accompanied by higher postprandial VLDL production than is found in obese men with lower levels of visceral AT. Increased postprandial insulin and free fatty acid (FFA) responses were also noted in men with high levels of visceral AT. Finally, postheparin plasma lipoprotein lipase activity was negatively correlated with the total-TRL-TG response in a subsample of 32 individuals (r = -0.37, P < 0.05). The results of the present study suggest that visceral obesity is associated with an impaired postprandial TG clearance. Furthermore, the exaggerated postprandial FFA response observed in subjects with high visceral AT suggests that visceral obesity may contribute to fasting and postprandial hypertriglyceridemia by altering FFA metabolism in the postprandial state.

A distributed hydrological model compatible with remote sensing and GIS has been developed over the past years. Run on microcomputers with a user-friendly interface, the HYDROTEL model can be applied to a wide range of watersheds with due account for available data, as a choice of options is offered for the simulation of the various processes. Algorithms derived as much as possible from physical processes, together with more conceptual or empirical algorithms have been selected. Also, natural units have been chosen for the simulations: small subwatersheds for the vertical water budget and flow toward the outlet of the unit and river reaches for channel flow. In this paper, the preparation of the watershed database from remotely sensed and geographic information system (GIS) data is discussed first. It is followed by a description of the various components of the model.

Satellite nodules are considered to be predictive of poor prognosis in breast cancer and in melanoma. In lung cancer, there is no information as to their definition, prevalence, or implication as a prognosis factor of survival after resection. Over the past 18 years (1969 to 1987), 84 patients underwent pulmonary resection for primary lung cancer accompanied by satellite nodules. These nodules were defined as well-circumscribed accessory carcinoma foci clearly separated from the main tumor but with identical histologic characteristics. All were smaller than the primary carcinoma and most were located within the same lobe. Survival rates of patients with satellite nodules were compared to those of 1021 patients without satellite nodules who underwent resection during the same time interval. The 1-, 3-, and 5-year survival rates for all patients classified as having no satellite nodules were 78%, 54%, and 44%, respectively, and the median survival for the entire group was 30 months. In patients with satellite nodules, these survival rates were 60.9%, 32.7%, and 21.6%, respectively, with a median survival of 15 months. The deleterious effect of satellite nodules was more significant in patients with stage I disease (p = 0.0008) than in patients with stage II (p = 0.0354) or stage III (p = 0.0145) disease. Survival data obtained by comparison of satellite nodule status and histologic characteristics shows that 5-year survival figures are better for patients with no satellite nodules in both the squamous and the nonsquamous groups. This study demonstrates that satellite nodules associated with lung cancer are indicative of locally advanced and/or premetastatic disease. These patients should be included in the stage group IIIa of the TNM stage grouping classification.

The present study examined the associations between a major adipokine, adiponectin, and adiposity indices as well as metabolic risk variables in a sample of 190 untreated asymptomatic men. Anthropometric measurements and a complete fasting plasma lipoprotein and lipid profile were obtained, and subjects underwent an oral glucose tolerance test. Fasting plasma adiponectin concentrations were determined by an ELISA. Although all adiposity and adipose tissue (AT) distribution indices were negatively correlated with plasma adiponectin levels (−0.14 ≤ r ≤ −0.32; P &amp;lt; 0.04), multiple regression analyses revealed that visceral AT accumulation was the only independent predictor of adiponectin levels, with 10% of its variance explained by visceral AT (P &amp;lt; 0.0001). Comparison of obese men with similar body mass index values (≥30 kg/m2) but who markedly differed in their level of visceral AT (&amp;lt; vs. ≥130 cm2; n = 15) revealed significant differences in adiponectin levels (7.0 ± 3.0 vs. 11.1 ± 4.9 μg/ml; P &amp;lt; 0.02 for men with high vs. low visceral AT, respectively). Finally, when men were stratified into tertiles of visceral AT and further classified on the basis of the 50th percentile of adiponectin levels (≤ vs. &amp;gt;8.8 μg/ml), a 3 × 2 ANOVA revealed an independent contribution of adiponectin on the variation of high-density lipoprotein cholesterol levels (P &amp;lt; 0.002) and of the glucose area (P &amp;lt; 0.02). These results support the notion that adiponectin concentration is influenced to a greater extent by visceral than sc obesity. Furthermore, adiponectin predicts glucose tolerance and plasma high-density lipoprotein cholesterol levels in a manner that is partly independent from the contribution of visceral adiposity.

Insulin resistance, hyperinsulinemia, hypertriglyceridemia, and low HDL-cholesterol concentrations are common features of a plurimetabolic syndrome, which increases the risk of coronary artery disease. Although it has been proposed that the development of atherosclerosis through alterations in plasma lipid levels could be a postprandial phenomenon, most studies on gender differences in plasma lipoprotein-lipid concentrations have reported fasting levels. Therefore, the aim of our study was to examine the response of postprandial triglyceride-rich lipoproteins to a standardized meal in 63 men and 25 women. In addition to the measurement of fasting and postprandial plasma lipid levels, numerous physical and metabolic variables were assessed, including body composition by underwater weighing and body fat distribution by computed tomography. Although no gender difference was noted in total body fat mass, men were characterized by a preferential accumulation of abdominal adipose tissue as revealed by an increased waist circumference and a greater visceral adipose tissue accumulation (50% difference) compared with women (P<0.001). Men also showed a greater plasma triglyceride response (P<0.005) as well as increased postprandial insulin and free fatty acid levels compared with women (P<0.01). Visceral adipose tissue was significantly associated with the postprandial triglyceride response in both genders (men: r=0.49, P<0. 0001; women: r=0.43, P<0.05). Finally, when men and women were matched for visceral adipose tissue accumulation, the gender difference in postprandial plasma triglyceride response was eliminated. Thus results of the present study suggest that the well known gender difference in visceral adipose tissue accumulation is an important contributing factor involved in the exaggerated postprandial triglyceride-rich lipoprotein response noted in men compared with women.

We have previously shown that the extracellular nucleoside triphosphate-hydrolyzing enzyme NTPDase2 is highly expressed in situ by stem/progenitor cells of the two neurogenic regions of the adult murine brain: the subventricular zone (type B cells) and the dentate gyrus of the hippocampus (residual radial glia). We explored the possibility that adult multipotent neural stem cells express nucleotide receptors and investigated their functional properties in vitro. Neurospheres cultured from the adult mouse SVZ in the presence of epidermal growth factor and fibroblast growth factor 2 expressed the ecto-nucleotidases NTPDase2 and the tissue non-specific isoform of alkaline phosphatase, hydrolyzing extracellular ATP to adenosine. ATP, ADP and, to a lesser extent, UTP evoked rapid Ca(2+) transients in neurospheres that were exclusively mediated by the metabotropic P2Y(1) and P2Y(2) nucleotide receptors. In addition, agonists of these receptors and low concentrations of adenosine augmented cell proliferation in the presence of growth factors. Neurosphere cell proliferation was attenuated after application of the P2Y(1)-receptor antagonist MRS2179 and in neurospheres from P2Y(1)-receptor knockout mice. In situ hybridization identified P2Y(1)-receptor mRNA in clusters of SVZ cells. Our results infer nucleotide receptor-mediated synergism that augments growth factor-mediated cell proliferation. Together with the in situ data, this supports the notion that extracellular nucleotides contribute to the control of adult neurogenesis.

Lipoprotein(a) [Lp(a)] is an atherogenic lipoprotein which is similar in structure to low density lipoproteins (LDL). The role of the LDL receptor in the catabolism of Lp(a) has been controversial. We therefore investigated the in vivo catabolism of Lp(a) and LDL in five unrelated patients with homozygous familial hypercholesterolemia (FH) who have little or no LDL receptor activity. Purified 125I-Lp(a) and 131I-LDL were simultaneously injected into the homozygous FH patients, their heterozygous FH parents when available, and control subjects. The disappearance of plasma radioactivity was followed over time. As expected, the fractional catabolic rates (FCR) of 131I-LDL were markedly decreased in the homozygous FH patients (mean LDL FCR 0.190 d-1) and somewhat decreased in the heterozygous FH parents (mean LDL FCR 0.294 d-1) compared with controls (mean LDL FCR 0.401 d-1). In contrast, the catabolism of 125I-Lp(a) was not significantly different in the homozygous FH patients (mean FCR 0.251 d-1), heterozygous FH parents (mean FCR 0.254 d-1), and control subjects (mean FCR 0.287 d-1). In summary, absence of a functional LDL receptor does not result in delayed catabolism of Lp(a), indicating that the LDL receptor is not a physiologically important route of Lp(a) catabolism in humans.

The spectral pattern of light attenuation in the ultraviolet (UV) and blue region (360–500 nm) was analyzed for seven high Arctic lakes. The best description of K d versus wavelength was obtained with an exponential model similar to the model used for absorption by chromophoric dissolved organic compounds (CDOM), but with an additional parameter (K back ) that accounts for background scattering: urn:x-wiley:19395590:media:lno20004530642:lno20004530642-math-0001 where K d (λ) is the diffuse vertical attenuation coefficient at wavelength λ and S is the exponential slope parameter that characterizes the decrease in attenuation with increasing wavelength. The inclusion of the background parameter gave a significantly better fit and eliminated the systematic deviations over the spectrum that occur in the absence of K back . The resultant S values (mean = 17.4 µm −1 ) were on average 47% higher than values calculated without a background parameter, and were more sensitive to between‐lake differences. The same pattern was found when S was estimated from spectral K d values in three literature data sets, so the new equation will generally increase the estimated values of S based on K d and provide a more accurate guide to intersystem variability. A compilation of literature data for S (based on K d and the new equation or on absorbance) showed that its mean value (±SE) is significantly higher in freshwaters (17.1 ± 0.7 µm −1 ) than in the sea (14.0 ± 0.4 µm −1 ). The variability in S was highest for low values of K d or a (340 nm values below 3 m −1 ). This pattern may be due to instrument‐related problems or more likely represents the real variability in the optical properties of CDOM in low colored systems. The analysis showed that S can vary significantly between and within systems (overall range = 9.2–36.2 µm −1 ) and that the value obtained also depends on the method of calculation, the wavelength range, and the type of optical measurement.

BACKGROUND AND PURPOSE: "Handicap situation" is defined in the literature as "a disruption in the accomplishment of a person's life habits (activities of daily living and social roles)." The purpose of this study was to determine the strength of association between various types of locomotion and the accomplishment of life habits, which is an indicator of the occurrence of handicap situations in children with cerebral palsy. SUBJECTS: Ninety-eight children with cerebral palsy, aged 5 to 17.8 years (mean = 10.5, SD = 3.5), were recruited. METHODS: The Life Habits Assessment was used to evaluate handicap situations in activities of daily living and social roles. Types of locomotion, the Pediatric Functional Independence Measure (locomotion section), and 2 tests representing functional activities (walking speed and stair climbing) were used as characteristics of locomotion. RESULTS: Locomotion capabilities were associated with the accomplishment of activities of daily living and social roles. Performance in variables related to locomotion, number of associated problems, and type of cerebral palsy explained 17% to 74% of the total variance in accomplishment of life habits in children who walked without technical aids. CONCLUSION AND DISCUSSION: The results suggest that locomotion might influence the accomplishment of life habits. Other factors, however--such as environmental barriers--should also be examined to determine their impact on the occurrence of handicap situations.

This review examines some agronomic, economic, and environmental impacts of herbicide-resistant (HR) canola, soybean, corn, and wheat in Canada after 10 yr of growing HR cultivars. The rapid adoption of HR canola and soybean suggests a net economic benefit to farmers. HR crops often have improved weed management, greater yields or economic returns, and similar or reduced environmental impact compared with their non-HR crop counterparts. There are no marked changes in volunteer weed problems associated with these crops, except in zero-tillage systems when glyphosate is used alone to control canola volunteers. Although gene flow from glyphosate-HR canola to wild populations of bird’s rape (Brassica rapa L.) in eastern Canada has been measured, enrichment of hybrid plants in such populations should only occur when and where herbicide selection pressure is applied. Weed shifts as a consequence of HR canola have been documented, but a reduction in weed species diversity has not been demonstrated. However, reliance on HR crops in rotations using the same mode-of-action herbicide and/or multiple in-crop herbicide applications over time can result in intense selection pressure for weed resistance and consequently, greater herbicide use in the future to control HR weed biotypes. History has repeatedly shown that cropping system diversity is the pillar of sustainable agriculture; stewardship of HR crops must adhere to this fundamental principle. Key words: Canola, Brassica napus, corn, Zea mays, soybean, Glycine max, wheat, Triticum aestivum, gene flow, herbicide resistance, transgenic crop, volunteer crop

The reuptake of dopamine into nerve terminals is the primary mechanism of inactivation of this neurotransmitter in the synaptic cleft. We report sex differences and estrous cycle variations of rat striatal dopamine uptake sites. During the estrous cycle, peak density of striatal dopamine uptake sites labelled with [3H]GBR-12935 occurred in the morning of proestrus in coincidence with peak dopamine, serotonin, dihydroxyphenylacetic acid and 5-hydroxytryptophan levels pointing to a presynaptic effect of gonadal hormones. Striatal homovanillic acid and 5-hydroxyindoleacetic acid levels as well as [3H]GBR-12935 binding affinity remained unchanged throughout the estrous cycle. The density of [3H]GBR-12935 striatal binding sites was lower in ovariectomized rats compared to intact female rats during the estrous cycle, whereas it was similar in gonadectomized male rats, intact male rats and ovariectomized rats. Binding affinity was in general similar for all the groups of rats examined. The affinity of dopamine for striatal [3H]GBR-12935 binding sites was similar in males and ovariectomized females, and did not change during the female estrous cycle. In summary, striatal dopamine uptake site density was lower in male compared to intact female rats and was shown to fluctuate during the female estrous cycle. These results suggest that gonadal hormones could influence the activity of psychoactive drugs acting on neuronal dopamine uptake sites.