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31
result(s) for
"Gibson, R.S"
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The evolution of large ocean waves: the role of local and rapid spectral changes
2007
or
Journal Article
Tissue iron deficiency and adiposity-related inflammation in disadvantaged preschoolers from NE Brazil
2014
Background/Objectives:
Earlier we reported an association between iron deficiency and overweight in Brazilian preschoolers. Here, we investigate whether this is the result of adipose-related inflammation.
Subjects/Methods:
Fasting serum C-reactive protein, α-1-acid glycoprotein (AGP), hepcidin, interleukin-6 (IL-6) and leptin, together with two iron biomarkers (serum ferritin and transferrin receptor (sTfR)), were measured in 364 disadvantaged preschoolers with a mean BMIZ (standardised Z-score for BMI) of 0.015, aged 3–6 years and attending day care in Salvador, Brazil. The role of genetic haemoglobin (Hb) disorders, intestinal parasites and dietary iron supply (calculated from serving sizes of 20 weekday menus) were also examined.
Results:
Forty-eight children (13%) were overweight (BMIZ >1). Prevalence of tissue iron deficiency (sTfR >113.3 nmol/l; 30.6 vs 12.5%;
P
=0.002) and chronic inflammation (AGP >25 μmol/l; 19 vs 10%;
P
=0.025) were higher in overweight than in normal-weight children. From multiple regression, BMIZ was a positive predictor of log serum sTfR, ferritin and leptin, but not of log hepcidin or IL-6. Instead, major positive predictors of log hepcidin were log IL-6, followed by an elevated AGP and sex (male), whereas for log IL-6 elevated AGP was the only significant predictor. Besides BMIZ, sex (female) was also a major positive predictor of leptin. Heterozygous variant of sickle cell Hb (
n
=20), but not helminths, was also a positive predictor of log sTfR. Median dietary iron supply (mg/day) was above the WHO Recommended Nutrient Intake assuming moderate bioavailability and appeared adequate.
Conclusions:
The role of adiposity-related inflammation in tissue iron deficiency should be considered even when the prevalence of overweight is relatively low.
Journal Article
Zinc status and cognitive function of pregnant women in Southern Ethiopia
2009
The relation between zinc status and cognitive function was examined in a cross-sectional study in the Sidama area of Southern Ethiopia. Pregnant women >24 weeks of gestation from three adjacent rural villages volunteered to participate. Mean (s.d.) plasma zinc of 99 women was 6.97 (1.07) micromol/l (below the cutoff of 7.6 micromol/l indicative of zinc deficiency at this stage of gestation). The Raven's Coloured Progressive Matrices (CPM) test was administered individually. Scores for the Raven's scale A, which is the simplest scale, ranged from 4 to 10 of a possible 12. Women with plasma zinc <7.6 micromol/l had significantly lower Raven's CPM scale A scores than women with plasma zinc concentrations >7.6 micromol/l. Plasma zinc and maternal age and education predicted 17% of the variation in Raven's CPM scale A scores. We conclude that zinc deficiency is a major factor affecting cognition in these pregnant women.
Journal Article
Complementary feeding practices and dietary intakes from complementary foods amongst weanlings in rural Malawi
2001
The objectives of this study were to estimate the quantity and nutritive quality of the complementary diet in rural Malawi, and to identify feeding practices, nutrients and dietary modifiers of iron and zinc bioavailability that may limit the quality of the diet.
This cross-sectional study design included an anthropometric survey, a feeding practices questionnaire, and an interactive, 24 h recall dietary data survey.
Four rural villages in Balaka district, southern Malawi.
Mothers resident in the study communities with breastfed children aged up to 24 months were eligible.
Stunting was prevalent among these weanlings. Maize was the predominant food source, with limited contribution of animal foods. Deficits in dietary energy and several nutrients were found when compared to estimated needs. When expressed per kg body weight, energy intakes appeared adequate. The bioavailability of zinc was low due to a high phytate:zinc molar ratio. Iron bioavailability was also low due to low intake of absorption enhancers such as meat/fish/poultry protein and ascorbic acid. Dietary quality was poorest for 6 to 8-month-old infants.
Iron, zinc and calcium were the most limiting nutrients to the quality of the diet, partly exacerbated by the poor bioavailability of iron and zinc. Increased total intake and bioavailability of iron and zinc would improve the complementary diets.
This study was funded by the Thrasher Research Fund, Salt Lake City, Utah, USA.
Journal Article
Zinc: the missing link in combating micronutrient malnutrition in developing countries
2006
The first cases of human Zn deficiency were described in the 1960s in the Middle East. Nevertheless, it was not until 2002 that Zn deficiency was included as a major risk factor in the global burden of disease, and only in 2004 did WHO/UNICEF include Zn supplements in the treatment of acute diarrhoea. Despite this recognition Zn is still not included in the UN micronutrient priority list, an omission that will continue to hinder efforts to reduce child and maternal mortality, combat HIV/AIDS, malaria and other diseases and achieve the UN Millennium Development Goals for improved nutrition in developing countries. Reasons for this omission include a lack of awareness of the importance of Zn in human nutrition, paucity of Zn and phytate food composition values and difficulties in identifying Zn deficiency. Major factors associated with the aetiology of Zn deficiency include dietary inadequacies, disease states inducing excessive losses or impairing utilization and physiological states increasing Zn requirements. To categorize countries according to likely risk of Zn deficiency the International Zinc Nutrition Consultative Group has developed indirect indicators based on the adequacy of Zn in the national food supplies and/or prevalence of childhood growth stunting. For countries identified as at risk confirmation is required through direct measurements of dietary Zn intake and/or serum Zn in a representative sample. Finally, in at risk countries either national or targeted Zn interventions such as supplementation, fortification, dietary diversification or modification, or biofortification should be implemented, where appropriate, by incorporating them into pre-existing micronutrient intervention programmes.
Journal Article
Mild iodine deficiency in a sample of New Zealand schoolchildren
2002
To assess the iodine status of New Zealand schoolchildren.
A proportionate to population size school-based cluster survey was used to randomly select children from two cities. The indicators used to assess iodine status were urinary iodine, as determined in a casual urine sample, and thyroid volume, as measured by ultrasonography. A qualitative food frequency questionnaire designed to ascertain frequency of consumption over the previous 3 months of foods or food groups that are good sources of dietary iodine, including iodized salt, was administered to each child.
Dunedin and Wellington, New Zealand.
Three-hundred children aged 8-10 y from 30 schools.
The median urinary iodine concentration of the children was 6.6 micro g/dl (interquartile range, 4.5-9.1). The percentage of children who had urinary iodine levels less than 5 micro g/dl was 31.4 (95% confidence interval (CI), 24.2-38.6). Comparison of thyroid volume with 2001 World Health Organization age/sex-specific and age/BSA-specific cut-off values resulted in a goitre prevalence of 11.3% (95% CI, 7.6-15.1) and 12.0% (95% CI, 7.9-16.1), respectively. Almost 30% of the children's caregivers did not use iodized salt in cooking and 51% of the children did not use iodized salt at the table.
Mild iodine deficiency was found in this sample of children. Iodized table salt may no longer be making a significant contribution to the iodine intakes of New Zealand children.
Journal Article
Improving the bioavailability of nutrients in plant foods at the household level
by
Hotz, Christine
,
Perlas, Leah
,
Gibson, Rosalind S.
in
Absorption
,
Acids
,
administration & dosage
2006
Plant foods are the major staples of diets in developing countries, in which the consumption of animal-source foods is often low because of economic and/or religious concerns. However, such plant-based diets are often associated with micronutrient deficits, exacerbated in part by poor micronutrient bioavailability. Diet-related factors in plant foods that affect bioavailability include: the chemical form of the nutrient in food and/or nature of the food matrix; interactions between nutrients and other organic components (e.g. phytate, polyphenols, dietary fibre, oxalic acid, protein, fat, ascorbic acid); pretreatment of food as a result of processing and/or preparation practices. Consequently, household strategies that reduce the content or counteract the inhibiting effects of these factors on micronutrient bioavailability are urgently needed in developing-country settings. Examples of such strategies include: germination, microbial fermentation or soaking to reduce the phytate and polyphenol content of unrefined cereal porridges used for young child feeding; addition of ascorbic acid-containing fruits to enhance non-haem-Fe absorption; heating to destroy heat-labile anti-nutritional factors (e.g. goitrogens, thiaminases) or disrupt carotenoid–protein complexes. Such strategies have been employed in both experimental isotope-absorption and community-based studies. Increases in Fe, Zn and Ca absorption have been reported in adults fed dephytinized cereals compared with cereals containing their native phytate. In community-based studies in rural Malawi improvements in dietary quality and arm-muscle area and reductions in the incidence of anaemia and common infections in young children have been observed.
Journal Article
Efficacy of a multi-micronutrient dietary intervention based on haemoglobin, hair zinc concentrations, and selected functional outcomes in rural Malawian children
2002
To investigate the efficacy of enhancing the content and bioavailability of micronutrients in diets of stunted rural Malawian children on their growth and body composition, morbidity, anaemia and hair zinc concentrations.
A quasi-experimental design with non-equivalent control group involving 410 intervention and 220 control children aged 30-90 months.
Children from two intervention and two control villages in Mangochi District, Southern Malawi participated in a 6 month dietary intervention. Anthropometry, malarial screening, haemoglobin, and hair zinc were measured at baseline and after 12 months, as well as socio-economic status at baseline, and common infections monthly post-intervention.
Groups were comparable at baseline. Post-intervention children had greater Z-scores for lean body mass (mid-upper arm circumference -0.75 vs -1.05; arm muscle area: 0.63 vs -1.03, P<0.001) than controls but Z-scores for weight-for-height and height-for-age were similar. After controlling for baseline variables, mean haemoglobin was higher (107 vs 102 g/l, P<0.01), whereas the incidence of both anaemia (62 vs 80%) and common infections (based on a median overall illness score for fever, diarrhoea, upper and lower respiratory infections) were lower in intervention compared to controls, with no change in hair zinc concentrations or malaria status post-intervention.
Improvements in the micronutrient adequacy of diets of post-intervention children were associated with a favourable increase in indices of lean body mass and reductions in the incidence of anaemia and common infections in these rural Malawian stunted children.
Journal Article
The relative validity of a computerized food frequency questionnaire for estimating intake of dietary iron and its absorption modifiers
2000
To determine the relative validity of an iron food frequency questionnaire (iron FFQ) designed to assess intakes of dietary iron and its absorption modifiers.
A computer-administered food frequency questionnaire was designed to estimate intake of total, non-haem, haem and meat iron as well as dietary components which influence iron absorption (vitamin C, phytate, calcium, grammes of meat/fish/poultry, tea and coffee) in women consuming a Western diet. The relative validity of the iron FFQ was assessed by comparing its results with those from weighed diet records collected over 11 days.
Dunedin, New Zealand.
Forty-nine women aged 19-31 y attending the University of Otago.
There was good agreement between the iron FFQ and the weighed diet records for median intakes of total iron, non-haem iron, calcium, tea and coffee. For dietary component intakes, correlations between the two methods ranged from 0.39 (for vitamin C) to 0.87 (for coffee) with 0.52 for total iron, and 0.61 for haem iron. In cross-classification with the weighed diet record, the iron FFQ correctly classified between 22% (for vitamin C) and 51% (for phytate) of participants into the same quartile. Actual values for surrogate categories indicated that the questionnaire can clearly differentiate between low and high intakes of all the dietary components assessed. The questionnaire also showed an acceptable level of agreement between repeat administrations (eg a correlation for total iron of 0.65).
The iron FFQ is appropriate for assessing group intakes of total iron, and iron absorption modifiers, in population studies to assess the aetiology and treatment of iron deficiency states in adult women consuming a Western diet.
This research was supported (in part) by a grant from the Health Research Council of New Zealand.
Journal Article
The evolution of large ocean waves: the role of local and rapid spectral changes. Proceedings of the Royal Society A: Mathematical,The evolution of large ocean waves: the role of local and rapid spectral changes
by
Swan, C
,
Gibson, R.S
2007
This paper concerns the formation of large-focused or near-focused waves in both unidirectional and directional sea-states. When the crests of wave components of varying frequency superimpose at one point in space and time, a large, transient, focused wave can occur. These events are believed to be representative of the largest waves arising in a random sea and, as such, are of importance to the design of marine structures. The details of how such waves form also offer an explanation for the formation of the so-called freak or rogue waves in deep water. The physical mechanisms that govern the evolution of focused waves have been investigated by applying both the fully nonlinear wave model of Bateman et al . (Bateman et al . 2001 J. Comput. Phys . 174 , 277–305) and the Zakharov's evolution equation (Zakharov 1968 J. Appl. Mech. Tech. Phys . 9 , 190–194). Aspects of these two wave models are complementary, and their combined use allows the full nonlinearity to be considered and, at the same time, provides insights into the dominant physical processes. In unidirectional seas, it has been shown that the local evolution of the wave spectrum leads to larger maximum crest elevations. In contrast, in directional seas, the maximum crest elevation is well predicted by a second-order theory based on the underlying spectrum, but the shape of the largest wave is not. The differences between the evolution of large waves in unidirectional and directional sea-states have been investigated by analysing the results of Bateman et al . (2001) using a number of spectral analysis techniques. It has been shown that during the formation of a focused wave event, there are significant and rapid changes to the underlying wave spectrum. These changes alter both the amplitude of the wave components and their dispersive properties. Importantly, in unidirectional sea-states, the bandwidth of the spectrum typically increases; whereas, in directional sea-states it decreases. The changes to the wave spectra have been investigated using Zakharov's equation (1968). This has shown that the third-order resonant effects dominate changes to both the amplitude of the wave components and the dispersive properties of the wave group. While this is the case in both unidirectional and directional sea-states, the consequences are very different. By examining these consequences, directional sea-states in which large wave events that are higher and steeper than second-order theory would predict have been identified. This has implications for the types of sea-states in which rogue waves are most likely to occur.
Journal Article