Underreporting of energy intake from a self-administered food-frequency questionnaire completed by adults in Montreal

BACKGROUND: Energy intake determined from self-reported dietary assessment methods may be underreported. Therefore, it is important that such methods be validated against another with known validity for energy intake or energy expenditure. METHODS: We investigated potential underestimation of energy intake obtained from our semi-quantitative food-frequency questionnaire (FFQ) administered between 2000 and 2001 in the metropolitan area of Montreal, Canada. The study population included 246 adults aged 18 to 82 years. The ratio of energy intake to estimated basal metabolic rate (EI/BMR) was used to assess underreporting and physical activity was determined from self-administered questions. Comparison of the EI/BMR ratio with the Goldberg statistical cut-off allowed us to detect individuals who were low energy reporters (LERs). LERs and non-LERs were compared to determine if they differed on sociodemographic, anthropometric and lifestyle variables. RESULTS: The EI/BMR ratio was 1.26 for men and 1.32 for women. LERs represented 43% of the sample of individuals. Male LERs accounted for 54% compared with 35% among females. Underreporting of energy intake was highest in men and individuals who were older, heavier, with higher body mass index and lower education level. A higher proportion of male LERs perceived their financial situation as adequate while a greater proportion of female LERs considered themselves poor. CONCLUSION: Our data suggest that underreporting of energy intake from the FFQ was considerable and may bias dietary interpretation. As this was uneven across the sample, it is crucial to recognise the characteristics of LERs in order to increase the validity of reported energy intake.     

Simplified enzymatic high-performance anion exchange chromatographic determination of total fructans in food and pet food-limitations and measurement uncertainty

A simplified method to determine total fructans in food and pet food has been developed and validated. It follows the principle of AOAC method 997.08, i.e., high-performance anion exchange chromatographic (HPAEC) determination of total fructose released from fructans (F(f)) and total glucose released from fructans (G(f)) after enzymatic fructan hydrolysis. Unlike AOAC method 997.08, calculation of total fructans is based on the determination of F(f) alone. This is motivated by the inherent difficulty to accurately determine low amounts of G(f) since many food and pet food products contain other sources of total glucose (e.g., starch and sucrose). In this case, a correction factor g can be used (1.05 by default) to take into account the theoretical contribution of G(f). At levels >5% of total fructans and in commercial fructan ingredients, both F(f) and G(f) can and should be accurately determined; hence, no correction factor g is required. The method is suitable to quantify total fructans in various food and pet food products at concentrations >or=0.2% providing that the product does not contain other significant sources of total fructose such as free fructose or sucrose. Recovery rates in commercial fructan ingredients and in selected food and pet food ranged from 97 to 102%. As part of a measurement uncertainty estimation study, individual contributions to the total uncertainty (u) of the total fructan content were identified and quantified by using the validation data available. As a result, a correlation between the sucrose content and the total uncertainty of the total fructan content was established allowing us to define a limit of quantitation as a function of the sucrose content. One can conclude that this method is limited to food products where the sucrose content does not exceed about three times the total fructan content. Despite this limitation, which is inherent to any total fructan method based on the same approach, this procedure represents an excellent compromise with regard to accuracy, applicability, and convenience.     

Fractionation of beta-lactoglobulin tryptic peptides by ampholyte-free isoelectric focusing.

Solutions of tryptic hydrolysate of bovine beta-lactoglobulin were fractionated by liquid-phase IEF in a preparative Rotofor cell at constant power for 2 h without ampholytes in order to identify interactions between peptides. The 20 peptide fractions collected were analyzed by capillary electrophoresis and SDS-PAGE under native, denaturing, and reducing conditions. The hydrolysate was shown to be composed mainly of acidic peptides (pI 2-5, 62%) of molecular mass below 6 kDa, and numerous disulfide bonds were detected. Purified peptides (beta-LG 15-20, 71-75, 76-82, and 84-91) were also focused individually and in mixtures and matched to components of the IEF fractions obtained from the tryptic hydrolysate of beta-LG. The separation of acidic (beta-LG 84-91) and basic (beta-LG 76-82) peptides was achieved by IEF, whereas uncharged peptides (beta-LG 15-20 and 71-75) were poorly separated due to their low electrophoretic mobility. Because no peptide-peptide interaction could be identified by IEF fractionation, it is suggested that electrical fields may decrease electrostatic interactions between charged peptides.     

Dynamic MRI and thermal simulation to interpret deformation and water transfer in meat during heating

Understanding and controlling structural and physical changes in meat during cooking is of prime importance. Nuclear magnetic resonance imaging (MRI) is a noninvasive, nondestructive tool that can be used to characterize certain properties and structures both locally and dynamically. Here we show the possibilities offered by MRI for the in situ dynamic imaging of the connective network during the cooking of meat to monitor deformations between 20 and 75 °C. A novel device was used to heat the sample in an MR imager. An MRI sequence was developed to contrast the connective tissue and the muscle fibers during heating. The temperature distribution in the sample was numerically simulated to link structural modifications and water transfer to temperature values. The contraction of myofibrillar and collagen networks was observed at 42 °C, and water began to migrate toward the interfascicular space at 40 °C. These observations are consistent with literature results obtained using destructive and/or nonlocalized methods. This new approach allows the simultaneous monitoring of local deformation and water transfer, changes in muscle structure and thermal history.     

Fungal, bacterial and plant dsDNA contributions to soil total DNA extracted from silty soils under different farming practices: Relationships with chloroform-labile carbon

Twelve differently-managed silty soils from North-Western France were chosen to compare two common methods of quantifying soil microbial biomass: Chloroform fumigation and extraction-labile carbon (CL_C) and microbial double stranded DNA (dsDNA). We also determined the contributions of each of the fungal, bacterial, and plant kingdoms to the total community dsDNA using real-time Polymerase Chain Reaction with kingdom-specific ribosomal primer sets. Regardless of the method, the highest microbial biomasses were associated with long-term untilled plots. Site (locations) specificities could also be detected, especially in conventionally cultivated lands. Regardless of site, a strong linear relationship could be drawn between CL_C and dsDNA in tilled lands (r = 0.91, n = 15, P = 0.01) and in grasslands (r = 0.78, n = 21, P = 0.01). Moreover, we propose a logarithmic model describing all of our silty soils, irrespective of management. In order to explain the non-linearity (log) of this relationship, we tested the hypothesis of a weak plant dsDNA contribution in total dsDNA in comparison with the well-documented root cell contribution to CL_C quantifications. Plant dsDNA never exceeded 2.6% of total dsDNA content for all of the soils studied. Among groups examined, the bacterial dsDNA contribution to the community dsDNA pool was the most site- and/or pedoclimatic-dependent. Fungi constituted a major component of total microbial biomass in grassland or in land with permanent plant cover where their proportion reached almost 50% of total dsDNA. More precisely, fungal dsDNA concentration was highly related to tillage. Our study demonstrated the expediency of the total microbial dsDNA quantification in agricultural silty soils rather than the time-consuming quantification of CL_C. Quantifying the relative contribution of bacterial or fungal biomass in total dsDNA by real-time PCR allows to access to a new level of knowledge of the soil microbial biomass and to reveal the balances between those two kingdoms according to soils or farming practices.     

How successful are plant species reintroductions?

Reintroduction of native species has become increasingly important in conservation worldwide for recovery of rare species and restoration purposes. However, few studies have reported the outcome of reintroduction efforts in plant species. Using data from the literature combined with a questionnaire survey, this paper analyses 249 plant species reintroductions worldwide by assessing the methods used and the results obtained from these reintroduction experiments. The objectives were: (1) to examine how successful plant species reintroductions have been so far in establishing or significantly augmenting viable, self-sustaining populations in nature; (2) to determine the conditions under which we might expect plant species reintroductions to be most successful; (3) to make the results of this survey available for future plant reintroduction trials. Results indicate that survival, flowering and fruiting rates of reintroduced plants are generally quite low (on average 52%, 19% and 16%, respectively). Furthermore, our results show a success rate decline in individual experiments with time. Survival rates reported in the literature are also much higher (78% on average) than those mentioned by survey participants (33% on average). We identified various parameters that positively influence plant reintroduction outcomes, e.g., working in protected sites, using seedlings, increasing the number of reintroduced individuals, mixing material from diverse populations, using transplants from stable source populations, site preparation or management effort and knowledge of the genetic variation of the target species. This study also revealed shortcomings of common experimental designs that greatly limit the interpretation of plant reintroduction studies: (1) insufficient monitoring following reintroduction (usually ceasing after 4 years); (2) inadequate documentation, which is especially acute for reintroductions that are regarded as failures; (3) lack of understanding of the underlying reasons for decline in existing plant populations; (4) overly optimistic evaluation of success based on short-term results; and (5) poorly defined success criteria for reintroduction projects. We therefore conclude that the value of plant reintroductions as a conservation tool could be improved by: (1) an increased focus on species biology; (2) using a higher number of transplants (preferring seedlings rather than seeds); (3) taking better account of seed production and recruitment when assessing the success of reintroductions; (4) a consistent long-term monitoring after reintroduction.     

Formation and stability of nanofibers from a milk-derived peptide

The objective of the present work was to investigate the physicochemical conditions that trigger the self-assembly of peptide β-lg f1-8 and therefore lead to nanofibers and hydrogel formation. Nanostructures formed by self-assembly of peptide β-lg f1-8 in the pH range of 2.0-11.0 were studied by transmission electron microscopy (TEM). Hydrogel formation was studied as a function of pH and resulted in evidence of a link between hydrogel formation and the charge distribution carried by the peptide structure. Finally, circular dichroism (CD) spectroscopy was used to characterize the effects of peptide concentration (0.4-2.0 mg/mL), ionic strength (0-1 M NaCl), and temperature (20-80 °C) on the secondary structure of peptide β-lg f1-8. Hydrogels were obtained at peptide concentrations above 2.5 mg/mL. Peptide concentration and pH adjustment were shown to trigger self-assembly of β-lg f1-8, but increasing ionic strength had no effect. Heating to 80 °C induced a stronger CD signal intensity due to an increase in solubility of the peptide, whereas only slight changes in CD pattern were found upon cooling to 20 °C. Overall, results emphasize the role of particular molecular interactions in β-sheet self-assembly of peptide β-lg f1-8 and pH-dependent electrostatic interactions occurring between β-lg f1-8 units, which can explain its propensity to self-assembly.     

Relationships between frost hardiness,root growth potential,and photosynthesis of nursery-grown white spruce seedlings

• Context  

Root growth is a characteristic to which nursery personnel is particularly attentive. The increase in root growth of white spruce seedlings in the autumn relies on the current season’s photosynthates. Needle hardening or a decrease in the mass of photosynthetically active foliage as a result of early frost may negatively affect the seedling’s photosynthetic capacity and its ability to fuel root growth.     

An Ulva armoricana extract protects plants against three powdery mildew pathogens

The protective activity of a crude extract prepared from the green macroalga, Ulva armoricana, previously shown to induce plant defence responses, was evaluated on three plant species, common bean, grapevine and cucumber, cultivated in the greenhouse and inoculated with three powdery mildew pathogens Erysiphe polygoni, E. necator and Sphareotheca fuliginea respectively. Chemical analyses showed that the extract was enriched in ulvans, which are green algae polysaccharides essentially composed of uronic acid and sulphated rhamnose. Weekly applications were performed by spraying of the green algal extract at various dilutions on bean, grapevine and cucumber leaves. A significant effect (50% protection) was observed using a dilution corresponding to about 3 g l⁻¹ dry matter and up to 90% reduction of symptom severity was obtained for the highest concentration (1/9 dilution, 6 g l⁻¹ dry matter) for the three plant species. To study the natural variability of the protective activity, five extracts prepared from algae batches harvested at different year periods were evaluated. Although polysaccharide composition varied among batches, all extracts elicit a reporter gene regulated by a defence-gene promoter in a transgenic tobacco line, and protect cucumber plants against powdery mildew infection. Together, these data demonstrate that U. armoricana is a reproducible source of active compounds which can be used to efficiently protect crop plants against powdery mildew diseases.     

Analysis of epidermal lipids in normal and atopic dogs,before and after administration of an oral omega-6/omega-3 fatty acid feed supplement. A pilot study

Alterations of the lipid expression in the skin of human and canine atopic subjects may be one of the key factors in the disease development. We have analyzed the ultrastructure of the clinically uninvolved skin of atopic dogs and compared it with the lipid composition of their tape-stripped stratum corneum (SC). The effect of a 2 month treatment of atopic dogs by food supplementation with a mixture of essential fatty acids was evaluated on skin samples taken before and after the treatment period. Electron microscopy revealed that the non-lesional skin of atopic dogs exhibited an abnormal and largely incomplete structure of the lamellar lipids with little cohesion between the corneocyte strata. The SC of atopic dogs was characterized by a significant decrease in the lipid content when compared to the healthy controls. Following oral supplementation with the mixture of essential fatty acids, the overall lipid content of the SC markedly increased. This feature was observed both with the free and, most importantly, with the protein-bound lipids (cholesterol, fatty acids and ceramides), the latter constituting the corneocyte-bound scaffold for ordinate organisation of the extracellular lipid bi-layers. Indeed, the semi-quantitative electron microscopy study revealed that the treatment resulted in a significantly improved organization of the lamellar lipids in the lower SC, comparable to that of the healthy dogs. Our results indicate the potential interest of long-term alimentary supplementation with omega-6 and omega-3 essential fatty acids in canine atopic dermatitis.