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At least 253 records · Page 14Linked to original sources
PubMed2006

Nonlinear time series analysis of food intake in the dab and the rainbow trout.

Evidence suggests that dab and rainbow trout are able to quickly adjust their food intake to an appropriate level when offered novel diets. In addition day-to-day and meal-to-meal food intake varies greatly and meal timing is plastic. Why this is the case is not clear: Food intake in fish is influenced by many factors, however the hierarchy and mechanisms by which these interact is not yet fully understood. A model of food intake may be helpful to understand these phenomena; to determine model type it is necessary to understand the qualitative nature of food intake. Food intake can be regarded as an autoregressive (AR) time series, as the amount of food eaten at time t will be influenced by previous meals, and this allows food intake to be considered using time series analyses. Here, time series data were analysed using nonlinear techniques to obtain qualitative information from which evidence for the hierarchy of mechanisms controlling food intake may be drawn. Time series were obtained for a group of dab and individuals and a group of rainbow trout for analysis. Surrogate data sets were generated to test several null hypotheses describing linear processes and all proved significantly different to the real data, suggesting nonlinear dynamics. Examination of topography and recurrence diagrams suggested that all series were deterministic and non-stationary. The point correlation dimension (PD2i) suggested low-dimensional dynamics. Our findings suggest therefore that any model of appetite should create output that is deterministic, non-stationary, low-dimensional and having nonlinear dynamics.

Animals↗
PubMedDate not supplied

Determination of cholecalciferol (vitamin D3) in selected foods by liquid chromatography: NMKL collaborative study.

Results are presented from an NMKL (Nordic Committee on Food Analysis) collaborative study of a method for the determination of cholecalciferol (vitamin D3) in foods. The method is based on the addition of an internal standard (vitamin D2), followed by saponification and extraction with n-heptane. The fraction that contains vitamin D2/D3 is separated by preparative normal-phase liquid chromatography (LC), and the analytes are determined by reversed-phase LC with UV detection at 265 nm. The method was tested by 8 participating laboratories. In this study 6 different matrixes were analyzed for cholecalciferol content: milk, liquid infant formula (gruel), cooking oil, margarine, infant formula, and fish oil. The contents varied from 0.4 to 12 microg/100 g. Three matrixes (milk, gruel, and margarine) were fortified with vitamin D3. In the other matrixes, vitamin D3 was added at 3 different levels at the Swedish National Food Administration. The milk was analyzed as a blind duplicate, whereas the other matrixes were analyzed as split-level pairs. The recoveries from the samples with vitamin D3 added varied from 93 to 102%. The repeatability relative standard deviation (RSDr) values for accepted results varied between 2.2% (fish oil) and 7.4% (cooking oil), whereas the reproducibility relative standard deviation (RSD(R)) values varied between 6.8% (margarine) and 24% (cooking oil).

Algorithms↗
PubMed1984

Alternatives in the collection and analysis of food frequency interview data.

In addition to frequency of consumption, a food frequency questionnaire may assess amount consumed, often by using food models, and the stability of diet. A food frequency interview directed at preformed vitamin A and beta-carotene was administered to 130 cases and 309 controls in an ongoing population-based case-control study of lung cancer in New Mexico. The questionnaire measured frequency, amount, and stability of consumption for 55 food items. Different combinations of responses to these three types of questions were used to calculate indices of total vitamin A consumption. The index based on frequency alone had the lowest value and increased significantly when amount was combined with frequency. Consideration of past consumption had relatively little effect on absolute and relative estimates of intake. Spearman rank order correlations between index pairs were high. These results suggest that the use of frequency alone is appropriate when the objective of data collection is to establish subjects' relative intake of specific nutrients.

Adult↗
PubMed2000

Characterization and determination of origin of lactic acid bacteria from a sorghum-based fermented weaning food by analysis of soluble proteins and amplified fragment length polymorphism fingerprinting.

The group that includes the lactic acid bacteria is one of the most diverse groups of bacteria known, and these organisms have been characterized extensively by using different techniques. In this study, 180 lactic acid bacterial strains isolated from sorghum powder (44 strains) and from corresponding fermented (93 strains) and cooked fermented (43 strains) porridge samples that were prepared in 15 households were characterized by using biochemical and physiological methods, as well as by analyzing the electrophoretic profiles of total soluble proteins. A total of 58 of the 180 strains were Lactobacillus plantarum strains, 47 were Leuconostoc mesenteroides strains, 25 were Lactobacillus sake-Lactobacillus curvatus strains, 17 were Pediococcus pentosaceus strains, 13 were Pediococcus acidilactici strains, and 7 were Lactococcus lactis strains. L. plantarum and L. mesenteroides strains were the dominant strains during the fermentation process and were recovered from 87 and 73% of the households, respectively. The potential origins of these groups of lactic acid bacteria were assessed by amplified fragment length polymorphism fingerprint analysis.

Bacterial Proteins↗
PubMed1994

Nutritional classification and analysis of food carbohydrates.

Dietary guidelines for Western countries encourage a considerable increase in carbohydrate intake. Because of new developments regarding nutritional properties of various food carbohydrates, these guidelines should include more precise recommendations of the carbohydrate composition. Small-intestinal digestibility is, nutritionally, the most important property of food carbohydrates. This was recognized early by British scientists, who differentiated between "available" and "unavailable" carbohydrates. Dietary fiber is generally defined as undigestible polysaccharides and lignin. Resistant starch is a newly discovered undigestible component included in such fiber definition, although current analysis methods do not recover all forms of resistant starch. The term "complex carbohydrates" has been used to mean digestible polysaccharides, ie, starch, in the United States, and to mean all polysaccharides, ie, both starch and nonstarch polysaccharides, in Europe. The term's usefulness is questionable because chain length of digestible carbohydrates is not related to specific nutritional advantages.

Dietary Carbohydrates↗
PubMed1999

Sources of errors in the quantitative analysis of food carotenoids by HPLC.

Several factors render carotenoid determination inherently difficult. Thus, in spite of advances in analytical instrumentation, discrepancies in quantitative results on carotenoids can be encountered in the international literature. A good part of the errors comes from the pre-chromatographic steps such as: sampling scheme that does not yield samples representative of the food lots under investigation; sample preparation which does not maintain representativity and guarantee homogeneity of the analytical sample; incomplete extraction; physical losses of carotenoids during the various steps, especially during partition or washing and by adsorption to glass walls of containers; isomerization and oxidation of carotenoids during analysis. On the other hand, although currently considered the method of choice for carotenoids, high performance liquid chromatography (HPLC) is subject to various sources of errors, such as: incompatibility of the injection solvent and the mobile phase, resulting in distorted or split peaks; erroneous identification; unavailability, impurity and instability of carotenoid standards; quantification of highly overlapping peaks; low recovery from the HPLC column; errors in the preparation of standard solutions and in the calibration procedure; calculation errors. Illustrations of the possible errors in the quantification of carotenoids by HPLC are presented.

Carotenoids↗
PubMed2003

Sulfur stable isotopes separate producers in marine food-web analysis.

Ecological applications of stable isotope analysis rely on different producers having distinct isotopic ratios to trace energy and nutrient transfer to consumers. Carbon (C) and nitrogen (N) are the usual elements analysed. We tested the hypothesis that producers unable to be separated using C and N would be separated by sulphur (S), by reviewing estuarine and marine food web studies using all three elements (total of 836 pairwise comparisons between producers). S had a wider range of values across all producers than C and N (S: 34.4, C: 23.3, N: 18.7 per thousand ), and a higher mean difference among producers (S: 9.3, C: 6.5, N: 3.3 per thousand ). We varied from 1 to 10 per thousand the distance producers must be apart to be considered separate. For each of these gap distances, S-separated producers tied on C and N in 40% or more of cases. Comparing the three elements individually, S had fewer tied pairs of producers for any gap distance than C or N. However, S also has higher within-producer variability. Statistical tests on simulated data showed that this higher variability caused S to be less effective than C for analysing differences among mean producer values, yet mixing models showed that S had the smallest confidence intervals around mean estimates of source contributions to consumers. We also examined the spatial and temporal scales over which S isotope signatures of the saltmarsh plant Spartina alterniflora varied. Differences between samples taken within tens of metres were smallest, but between samples hundreds of metres apart were as different as samples thousands of kilometres apart. The time between samples being taken did not influence S signatures. Overall, the use of S is recommended because it has a high probability of distinguishing the contribution of different producers to aquatic food webs. When two elements are employed, the combination of S and C separates more producers than any other combination.

Animals↗
PubMed1985

Molecular analysis confirms food source and simultaneous involvement of two distinct but related subgroups of Salmonella typhimurium bacteriophage type 10 in major interprovincial Salmonella outbreak.

More than 2,000 confirmed cases of food poisoning occurred in the four Atlantic provinces of Canada and in Ontario during the second and third quarters of 1984. Salmonella typhimurium phage type 10 was identified as the etiologic agent, and cheddar cheese was implicated as the source of infection. Strains isolated from infected humans and from cheese were indistinguishable by biotyping, antibiotic resistance typing, and phage typing. Plasmid analysis confirmed cheese as the source of infection and revealed the presence of two molecular subgroups of bacteriophage type 10. Group I strains carried 57-, 22.3-, and 3.4-kilobase (kb) plasmids; group II strains carried 57-, 4.6-, and 3.4-kb plasmids. Digestion with endonucleases HaeIII, HpaII, and AvaIII indicated that the 3.4-kb plasmids were identical. This outbreak was, therefore, caused by a mixed infection with two distinct but related bacteria. Group I strains are fairly common among Canadian S. typhimurium phage type 10 isolates, whereas group II strains appeared to be unique to this outbreak.

Canada↗
PubMed2006

Contrast media and nephropathy: findings from systematic analysis and Food and Drug Administration reports of adverse effects.

CONTEXT: Recent studies suggest differences in the incidence of contrast-induced nephropathy (CIN) among contrast media (CM). OBJECTIVE: To determine whether there are significant differences among low-osmolality CM (LOCM) in the incidence of contrast-induced nephropathy (CIN), we reviewed published studies of CIN in renally impaired patients and conducted statistical data mining using databases of adverse events maintained by the U.S. Food and Drug Administration (FDA). DATA SOURCES: A systematic literature search was performed for prospective, controlled, English language studies published in peer-reviewed journals that reported CIN rates in renally impaired patients after a specific LOCM. Databases searched were EMBASE, MEDLINE, Biosis Previews, Derwent Drug File, Pascal, and SciScearch Cited Ref Sci. For the FDA analysis, we used the SRS and AERS databases. DATA SELECTION: Twenty-two studies reporting data in 3112 patients with renal impairment met the inclusion criteria. Most studies reported on the use of a pharmacologic intervention to prevent CIN. From the FDA databases, we evaluated 18 adverse event terms associated with renal injury or dysfunction after CM use. DATA EXTRACTION: Data from 22 studies were entered into a database. A meta-regression analysis using a mixed effect model was performed. CM effect was adjusted by the following covariates: baseline patient characteristics (mean age, gender distribution) and risk factors (prevalence of diabetes mellitus, degree of renal impairment, CM volume), and the use of prophylactic drug treatments. Multiple disproportionality analyses (adjusted odds ratio, adjusted empirical Bayesian estimate, or Bayesian logistic regression) were performed on the FDA databases to estimate associations between 4 CM and 18 AE terms related to CIN. DATA SYNTHESIS: Systematic analysis of clinical trials suggest the highest incidence of CIN occurs in patients receiving iohexol and the lowest incidence in patients receiving iopamidol, even when corrected for other CIN risk factors. Statistical data mining of FDA data also showed the highest association of CIN for iohexol and the lowest for iopamidol. CONCLUSIONS: The risk of CIN was higher in patients receiving iohexol compared with patients receiving iopamidol. No significant differences were found comparing iohexol to other LOCMs, including iodixanol.

Bayes Theorem↗
PubMedDate not supplied

Value assignment of nutrient concentrations in five standard reference materials and six reference materials.

A number of food-matrix reference materials (RMs) are available from the National Institute of Standards and Technology (NIST) and from Agriculture Canada through NIST. Most of these materials were originally value-assigned for their elemental composition (major, minor, and trace elements), but no additional nutritional information was provided. Two of the materials were certified for selected organic constituents. Ten of these materials (Standard Reference Material [SRM] 1,563 Cholesterol and Fat-Soluble Vitamins in Coconut Oil [Natural and Fortified], SRM 1,566b Oyster Tissue, SRM 1,570a Spinach Leaves, SRM 1,974a Organics in Mussel Tissue (Mytilus edulis), RM 8,415 Whole Egg Powder, RM 8,418 Wheat Gluten, RM 8,432 Corn Starch, RM 8,433 Corn Bran, RM 8,435 Whole Milk Powder, and RM 8,436 Durum Wheat Flour) were recently distributed by NIST to 4 laboratories with expertise in food analysis for the measurement of proximates (solids, fat, protein, etc.), calories, and total dietary fiber, as appropriate. SRM 1846 Infant Formula was distributed as a quality control sample for the proximates and for analysis for individual fatty acids. Two of the materials (Whole Egg Powder and Whole Milk Powder) were distributed in an earlier interlaboratory comparison exercise in which they were analyzed for several vitamins. Value assignment of analyte concentrations in these 11 SRMs and RMs, based on analyses by the collaborating laboratories, is described in this paper. These materials are intended primarily for validation of analytical methods for the measurement of nutrients in foods of similar composition (based on AOAC INTERNATIONAL's fat-protein-carbohydrate triangle). They may also be used as "primary control materials" in the value assignment of in-house control materials of similar composition. The addition of proximate information for 10 existing reference materials means that RMs are now available from NIST with assigned values for proximates in 6 of the 9 sectors of the AOAC triangle. Five of these materials have values assigned for total dietary fiber-the first such information provided for materials available from NIST.

Chromatography, Gas↗
PubMed1984

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Concordance of nutrient information obtained by different methods.

Data obtained from two vegetarian and two nonvegetarian populations by 24-h diet recall, 3-day weighed diet diary, analysis of 3-day composite food samples, and measurement of certain biochemical parameters were compared. Correlations for group means (both sexes combined) for values obtained by 24-h recall versus 3-day diet diary were protein, r = 0.96 and total calories r = 0.86. For 3-day diet diary with food analysis, protein r = 0.89, fat r = 0.90 and for reported protein intake with serum prealbumin r = 0.74, with urinary urea nitrogen r = 0.87. Correlations were low for comparisons of means of male groups for most parameters. Individual correlations for reported protein intake and biochemical parameters were lower for males than for females. This suggests that male subjects may require special attention to insure accuracy of reporting and specimen collection. These findings indicate comparability of data from 24-h recall and 3-day diary, and agreement of dietary records with certain biochemical parameters. Protein and fat intake as determined from chemical analysis of a composite food sample correlated well (r = 0.89; r = 0.90) with that calculated from food tables.

Adult↗
PubMed1999

Dental caries in pre-school children: associations with social class, toothbrushing habit and consumption of sugars and sugar-containing foods. Further analysis of data from the National Diet and Nutrition Survey of children aged 1.5-4.5 years.

This project examined the relative significance of dietary sugars, toothbrushing frequency and social class as predictors of caries experience (caries vs. no caries) among 1,450 British pre-school children who took part in the National Diet and Nutrition Survey. This cross-sectional survey was based on a representative sample of children aged 1.5-4.5 years studied in 1992/3. Children were classified into four groups according to social class and toothbrushing habit. Diet/caries associations were examined for biscuits and cakes, sugar confectionery, chocolate confectionery and soft drinks, and the percentage of energy from non-milk extrinsic sugars, using data on amount and frequency of consumption from 4-day weighed dietary records. In stepwise logistic regressions, the strength of the association between social class and caries experience was twice that between toothbrushing and caries, and nearly three times that between sugar confectionery and caries (other dietary variables were not significant). The association of caries with sugar confectionery (both in amount and frequency) was only present among children whose teeth were brushed less than twice a day. Toothbrushing frequency appeared to have a stronger impact on caries prevention in non-manual compared with manual children. Household expenditure on confectionery was associated with caries only among children from the manual group. The findings suggest the hypothesis that regular brushing (twice a day) with a fluoride toothpaste may have greater impact on caries in young children than restricting sugary foods.

Age Factors↗
PubMed1983

Filament hygrometer for water activity measurement: interlaboratory evaluation.

A method is presented for measuring water activity (aw) of foods with a filament hygrometer. An interlaboratory evaluation carried out for the Nordic Committee on Food Analysis demonstrated that measurements can be made with a repeatability and reproducibility of 0.005 and 0.010 aw, respectively. The critical parameters of aw measurements are defined and discussed in relation to the accuracy and reproducibility required. The need for strictly standardized procedures for maintenance of the equipment, sample treatment, calibration, and measuring is emphasized.

Food Analysis↗
PubMed2001

Electrochemical biosensors for evaluation of contaminants in food.

This paper describes the application of electrochemical disposable biosensors in food analysis, which have recently been developed in our laboratory. Disposable biosensors, based on acetylcholinesterase inhibition activity, were exploited for testing the presence of organophosphorus and carbamate pesticides in water, fruit, and vegetable samples. The paper further describes preliminary tests for the detection of genetically modified organisms and hybridisation by coupling the DNA biosensors with the polymerase chain reaction.

Biosensing Techniques↗
PubMed2005

Sensor and biosensor preparation, optimisation and applications of Prussian Blue modified electrodes.

Being one of the most commonly used electrochemical mediators for analytical applications, Prussian Blue has found a wide use in the biosensor field during the last years. Its particular characteristic of catalysing hydrogen peroxide reduction has been applied in the construction of a large number of oxidase enzyme-based biosensors for clinical, environmental and food analysis. By modifying an electrode surface with Prussian Blue, it is in fact possible to easily detect hydrogen peroxide at an applied potential around 0.0 V versus Ag/AgCl, thus making possible coupling with oxidase enzymes while also avoiding or reducing electrochemical interferences. Papers dealing with glucose, lactate, cholesterol and galactose biosensors that are based on the use of Prussian Blue have recently appeared in the most important analytical chemistry journals. Another recent trend is the use of a choline probe based on choline oxidase for pesticide determination to exploit the inhibition of acetylcholinesterase by these compounds. In addition, the use of Prussian Blue in the development of biosensors for food analysis has captured the interest of many research groups and led to improved methods for the detection of glutamate, galactose, alcohol, fructosyl amine, formate, lysine and oxalate. This review will focus on the biosensing aspects of Prussian Blue-based sensors giving a general overview of the advantages provided by such mediator as well as its drawbacks. A comprehensive bibliographic reference list is presented together with the most up to date research findings in this field and possible future applications. The commercial potential of sensors based on this mediator will also be discussed.

Biosensing Techniques↗
PubMed1995

Patterns of chlorinated biphenyl congeners in harbor seals (Phoca vitulina) and in their food: statistical analysis.

Patterns of chlorinated biphenyl (CB) congeners have been compared in two groups of samples, namely blood samples from harbor seals (Phoca vitulina) and muscle tissue samples in the fish with which the seals were fed. The data originate from a Dutch controlled feeding study, performed in 1981 and 1983. The seals were living in captivity in two separate groups, and the fish samples were plaice (Pleuronectes platessa) from the Dutch part of the Wadden sea and mackerel (Scomber scombrus) from the Atlantic ocean. The levels of CB congeners were different in the two types of fish. The CB congener patterns of these four "matrices" were compared by analysis of principal components, and were found to be different in the two groups of harbor seals, which were fed the different types of fish. The corresponding CB congener patterns of the two groups of fish were also different. There was no indication for a relatively larger impact of biotransformation due to induction of isoforms of the cytochrome P450-system at the higher absolute CB congener levels in the Wadden sea group of seals compared to the Atlantic group of seals. The differentiation between the CB congener patterns in the two groups of seals in the Dutch study can be ascribed solely to different CB congener patterns in their food. The difference between CB congener patterns in the seals and in their diet can be explained by the structure-related biotransformation of the CB congeners in the harbor seal.

Animals↗
PubMed2005

Are effects of MTHFR (C677T) genotype on BMD confined to women with low folate and riboflavin intake? Analysis of food records from the Danish osteoporosis prevention study.

We have previously found BMD and fracture risk to be significantly associated with the MTHFR (C677T) polymorphism in healthy postmenopausal women in the first years after menopause. Since then, other cohort studies have suggested that sufficient intake of riboflavin and/or folate may have the potential to prevent development of low BMD in women with the TT genotype. This could to some extent explain why this polymorphism is associated with low BMD or fracture in some study populations and not in others. It would also indicate that fractures associated with the TT genotype could be preventable by vitamin B supplementation. We have, therefore, reviewed baseline food record data from our original study to determine if BMD and fracture associations with the MTHFR genotype depended on the intake of folate, riboflavin, or other members of the vitamin B complex, associated with homocysteine metabolism. We analyzed genotype, BMD, and dietary records from 1700 healthy postmenopausal women who participated in the DOPS study. For the assessment of fracture risk, we used longitudinal observations from 854 women in the control group who remained compliant with their initial allocation of no treatment. Riboflavin intake was significantly correlated with femoral neck (FN) BMD in women with the TT genotype (r = 0.24, P < 0.01). FN and lumbar spine (LS) BMD were only associated with the MTHFR genotype in the lowest quartile of riboflavin intake. At the FN, similar threshold effects were shown for folate, vitamin B12, and vitamin B6. Among these vitamin B complex members, stepwise regression analysis identified riboflavin as the only significant predictor of FN BMD in the TT genotype. In conclusion, we confirm reports that BMD in the MTHFR TT genotype is only significantly reduced in the lowest quartile of riboflavin, B12, B6, and folate intake, at least at the time of menopause. Vitamin B supplementation would only be expected to benefit BMD in about 2% of the population, i.e., those with the TT genotype and low vitamin B intake.

Bone Density↗