Inter- and intra-individual variability of active glucagon-like peptide 1 among healthy adults.

Objective: To determine whether sex, age, and body mass index are correlated with active glucagon-like-peptide 1 concentrations and to investigate glucagon-like-peptide 1 reproducibility during repeated oral glucose tolerance tests. Methods: Sixty-one healthy volunteers underwent four 2-hour repeated oral glucose tolerance tests approximately 1 week apart. Because this randomized same-subject crossover trial was designed to investigate effects of non-nutritive sweeteners, participants received 355 mL (12 ounces) of water or a beverage containing non-nutritive sweeteners 10 minutes prior to each oral glucose tolerance test. Blood samples were collected 10 minutes before, and 0, 10, 20, 30, 60, 90, and 120 minutes following ingestion of 75 grams of glucose. Results: Basal active glucagon-like-peptide 1, peak glucagon-like-peptide 1, and glucagon-like-peptide 1 area-under-the-curve were higher in men than women (all p ≤0.04), adjusting for body mass index and age. Fasting and stimulated active glucagon-like-peptide 1 results were highly reproducible with little within-subject variability (between-subjects to within-subject variability ratio 4.2 and 3.5 for fasting glucagon-like-peptide 1 and glucagon-like-peptide 1 area-under-the-curve). Conclusion: Men had higher active glucagon-like-peptide 1 concentrations than women. In contrast to considerable inter-individual variability of basal and stimulated active glucagon-like-peptide 1 concentrations, intra-individual variability was low, consistent with tight physiological regulation.

Cigarette characteristic and emission variations across high-, middle- and low-income countries.

OBJECTIVES: The public health burden of tobacco use is shifting to the developing world, and the tobacco industry may apply some of its successful marketing tactics, such as allaying health concerns with product modifications. This study used standard smoking machine tests to examine the extent to which the industry is introducing engineering features that reduce tar and nicotine to cigarettes sold in middle- and low-income countries. STUDY DESIGN: Multicountry observational study. METHODS: Cigarettes from 10 different countries were purchased in 2005 and 2007 with low-, middle- and high-income countries identified using the World Bank's per capita gross national income metric. Physical measurements of each brand were tested, and tobacco moisture and weight, paper porosity, filter ventilation and pressure drop were analysed. Tar, nicotine and carbon monoxide emission levels were determined for each brand using International Organization for Standardization and Canadian Intensive methods. Statistical analyses were performed using Statistical Package for the Social Sciences. RESULTS: Among cigarette brands with filters, more brands were ventilated in high-income countries compared with middle- and low-income countries [χ(2)(4)=25.92, P<0.001]. Low-income brands differed from high- and middle-income brands in engineering features such as filter density, ventilation and paper porosity, while tobacco weight and density measures separated the middle- and high-income groups. Smoke emissions differed across income groups, but these differences were largely negated when one accounted for design features. CONCLUSIONS: This study showed that as a country's income level increases, cigarettes become more highly engineered and the emissions levels decrease. In order to reduce the burden of tobacco-related disease and further effective product regulation, health officials must understand cigarette design and function within and between countries.

Using 15N to determine a budget for effluent-derived nitrogen applied to forest.

Using stable N isotopes, the fate of effluent-derived N has been determined within a land based municipal effluent irrigation scheme. Over 900 metric tonnes(t) of effluent-derived N have been applied to 192 ha of production conifer forest near Rotorua (NZ) over the past 11 years. The effluent N has a natural isotopic signal, generated by the treatment process, allowing it to be traced into various components of the system. Using this isotopic signal, a realistic approximation of storage capacity of various components of the system has been generated, including a calculation of the contribution of effluent N exiting the catchment via stream flow. Forest storage accounts for 50% of the applied N with a considerable proportion of that immobilized in wood and soil. The wetland, although not intensively sampled, retains 115 t, (13%) of the applied N. Denitrification, including that occurring within the wetland, accounts for 23 t (3%). Nitrogen isotope data confirm that the rise in NO3 concentrations is directly attributable to effluent N. Currently 88% of NO3-N in the stream is effluent-derived. Using current N isotope values for the stream and extrapolating over the discharge period, export of effluent N via the stream is estimated as 263 t (29%) of the applied N. Overall the forest and wetland ecosystem has intercepted or denitrified 65% of applied N, with 29% lost to the stream, and 50 t (5%) unaccounted for. The forest ecosystem is currently over-supplied with N and a number of management implications flows from these findings. In the long term the continued application of effluent N to the current irrigation area is not sustainable.