Prevalence and severity of asthmatic symptoms in Grenadian school children: the Grenada National Asthma Survey

OBJECTIVE

The goal of this study was to determine the prevalence of asthma in school children in the tri-island Caribbean nation of Grenada.

SETTING, PARTICIPANTS AND OUTCOMES

This was a self-report study provided to the guardians of all primary school children between ages 6 and 7 throughout Grenada, Carriacou and Petite Martinique in 2013. Of the 2362 surveys provided, 1374 were returned, resulting in a response rate of 58.2%. Only responders listing birthdays between 1 January 2006 and 31 December 2007 were included in the analysis, resulting in 1165 qualifying responders. Asthma diagnosis was based on previous physician diagnosed asthma and/or self-reported presence of wheeze in the past 12 months (current wheeze). Severity of asthma, medication usage, environmental exposures, physician and emergency department visits were compared among respondents.

RESULTS

The prevalence of wheezing in the past year was 30.5±1.8%, and of these 68.4% were previously diagnosed with asthma. Of the current wheeze participants, 39.9±9.2% reported moderate to severe asthma symptoms and increased exposure to cigarette smoke, excessive dust, burning brush and landfills. Carriacou and Petite Martinique, the two smaller islands, had a lower incidence of current wheeze (14.1±7.7%) and exposure rates to cigarette smoke and burning brush as compared to the larger, denser island of Grenada. Although 65.7% of respondents diagnosed with asthma reported taking medication, the number of annual doctor and emergency department visits were high (2.82 and 0.86, respectively). Respondents with the most severe asthma symptoms reported the most emergency department visits with an average of 1.05 visits annually, whereas respondents with moderate asthma symptoms had the most doctor visits with an average of 3.33 visits annually.

CONCLUSIONS

This study indicates that the prevalence of childhood asthma in Grenada is very high and warrants policy consideration in public health and education to decrease its morbidity.

2-arachidonoylglycerol signaling in forebrain regulates systemic energy metabolism

The endocannabinoid system plays a critical role in the control of energy homeostasis, but the identity and localization of the endocannabinoid signal involved remain unknown. In the present study, we developed transgenic mice that overexpress in forebrain neurons the presynaptic hydrolase, monoacylglycerol lipase (MGL), which deactivates the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG). MGL-overexpressing mice show a 50% decrease in forebrain 2-AG levels but no overt compensation in other endocannabinoid components. This biochemical abnormality is accompanied by a series of metabolic changes that include leanness, elevated energy cost of activity, and hypersensitivity to β(3)-adrenergic-stimulated thermogenesis, which is corrected by reinstating 2-AG activity at CB(1)-cannabinoid receptors. Additionally, the mutant mice are resistant to diet-induced obesity and express high levels of thermogenic proteins, such as uncoupling protein 1, in their brown adipose tissue. The results suggest that 2-AG signaling through CB(1) regulates the activity of forebrain neural circuits involved in the control of energy dissipation.

Diacylglycerol lipase-alpha and -beta control neurite outgrowth in neuro-2a cells through distinct molecular mechanisms

The endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG) is produced through hydrolysis of 1,2-diacyl-sn-glycerol (DAG), which is catalyzed by DAG lipase (DGL). Two DGL isoforms have been molecularly cloned, but their respective roles in endocannabinoid signaling have not been fully elucidated. Here, we report that DGL-α and DGL-β may contribute to all-trans-retinoic acid (RA)-induced neurite outgrowth in neuroblastoma Neuro-2a cells through distinct mechanisms. RA-induced differentiation of Neuro-2a cells was associated with elevations of cellular 2-AG levels and DGL activity, which were accompanied by temporally separated transcription of DGL-α and DGL-β mRNA. Knockdown of either DGL-α or DGL-β expression attenuated neurite outgrowth, which indicates that both isoforms contribute to neuritogenesis. Immunostaining experiments showed that DGL-β is localized to perinuclear lipid droplets, whereas DGL-α is found on plasma membranes. After RA-induced differentiation, both DGL-α- and DGL-β-green fluorescent protein were distributed also in neurites but in distinguishable patterns. Overexpression of either DGL-α or DGL-β increased the number of neurite-bearing cells, but DGL-β caused substantially larger morphological changes than DGL-α did. Finally, the cannabinoid-1 antagonist rimonabant (1 μM) inhibited DGL-α-induced neuritogenesis, whereas it had no such effect on DGL-β-induced morphological differentiation. The results indicate that RA-induced DGL expression is required for neurite outgrowth of Neuro-2a cells. The findings further suggest that DGL-α and -β may regulate neurite outgrowth by engaging temporally and spatially distinct molecular pathways.