Measurement is the foundation of research and theory on children's eating behaviours: Current issues and directions for progress.

Eating behaviours affect food intakes and are involved in the aetiology of obesity. There has been impetus to translate findings about children's eating behaviour into intervention and policy programs. However, measurement limitations have hindered our capacity to understand and influence children's eating behaviours. In the present paper we provide an overview of some of the key methodological and measurement issues facing the field of children's eating behaviours and highlight implications for research and health promotion. Drawing on insight from parallel issues that occur in the measurement of early social and emotional development, we examine two overlapping themes in children's (aged 0-∼12 years) eating behaviours (1) measurement issues related to validity and reliability, and (2) associated methodological challenges, such as contextual influences and the importance of designing studies that use multiple informants and multiple methods. We then suggest insights and strategies aimed at advancing approaches to measurement of children's eating behaviours. To progress our understanding of children's eating behaviours, we conclude that a range of psychometrically sound, fit-for-purpose measurement instruments and procedures are needed for use in multi-trait, multi-method, multi-informant studies in a range of populations and contexts.

The Feeding Practices and Structure Questionnaire: development and validation of age appropriate versions for infants and toddlers.

BACKGROUND: In order to measure and understand trajectories of parental feeding practices and their relationship with child eating and weight, it is desirable to perform assessment from infancy and across time, in age-appropriate ways. While many feeding practices questionnaires exist, none is presently available that enables tracking of feeding practices from infancy through childhood. The aim of the study was to develop a version of the Feeding Practices and Structure Questionnaire (FPSQ) for parents with infants and toddlers (< 2 years) to be used in conjunction with the original FPSQ for older children (≥2 years) to measure feeding practices related to non-responsiveness and structure across childhood. METHODS: Constructs and items for the FPSQ for infants and toddlers were derived from the existing and validated FPSQ for older children and supplemented by a review of the literature on infant feeding questionnaires. Following expert review, two versions of the questionnaire were developed, one for milk feeding parents and one for solid feeding parents. Data from two studies were combined (child ages 0-24 months) to test the derived constructs with Confirmatory Factor Analysis for the milk feeding (N = 731) and solid feeding (N = 611) versions. RESULTS: The milk feeding version consisted of four factors (18 items) and showed acceptable model fit and good internal reliability: 'feeding on demand vs. feeding routine' (α = 0.87), 'using food to calm' (α = 0.87), 'persuasive feeding' (α = 0.71), 'parent-led feeding' (α = 0.79). The same four factors showed acceptable model fit for the solid feeding version (21 items), likewise with good internal reliability (α = 0.74, 0.86, 0.85, 0.84 respectively). Two additional factors (13 items) were developed for the solid feeding version that appeared developmentally appropriate only for children aged 12 months or older: 'family meal environment' (α = 0.81) and 'using (non-)food rewards' (α = 0.92). The majority of factor-factor correlations were in line with those of the original FPSQ. CONCLUSIONS: The FPSQ milk and solid feeding versions are the first measures specifically developed as precursors to the FPSQ to measure parental feeding practices in children < 2 years, particularly practices related to non-responsiveness and structure. Further validation in more diverse samples is required.

Do children's food preferences align with dietary recommendations?

OBJECTIVES: To examine how Australian children's reported everyday food preferences reflect dietary recommendations, and the impact of sociodemographic factors on these associations. DESIGN: Cross-sectional survey. SETTING/SUBJECTS: Three hundred and seventy-one parents of children aged 2-5 years, recruited from three socio-economic groups in two Australian cities, completed a survey on their child's liking for 176 foods and drinks on a 5-point Likert scale in addition to demographic descriptors. Preferences were compared with the recommendations of the Dietary Guidelines for Children and Adolescents in Australia and the Australian Guide to Healthy Eating. RESULTS: Foods in the Extra Foods (non-nutritious foods) and Cereals groups of the Australian Guide to Healthy Eating were highly liked (mean: 4.02 and 4.01, respectively), whilst foods in the Vegetables group were liked least (mean: 3.01). A large percentage of foods in the Cereals and Extra Foods groups were liked (64% and 56%, respectively) in contrast to the other food groups, especially Vegetables (7%). Children liked foods that were higher in sugar (r = 0.29, P < 0.0001) and more energy-dense (r = 0.34, P < 0.0001) but not those higher in saturated fat (r = 0.16, P = 0.03), total fat (r = 0.12, P = 0.12) or sodium (r = 0.10, P = 0.18). Sociodemographic variables (e.g. socio-economic status, parental education, children's age and sex) explained little of the variation in children's food preferences. CONCLUSIONS: Australian pre-school children's food preferences align with dietary guidelines in some respects, but not others. Interventions are needed to shift children's preferences away from non-nutritious foods that are high in energy density and sugar, and towards vegetables and fruits.

Predicting intentions to consume functional foods and supplements to offset memory loss using an adaptation of protection motivation theory.

The widespread use of dietary supplements and so-called 'functional foods' is thought to be partially motivated by self-control of health. However, whilst consumers want foods associated with well-being or disease prevention, they are unlikely to be willing to compromise on taste or technology. This presents a dilemma for promoters of functional foods. Middle-aged consumers' intentions to consume functional foods or supplements that may improve memory were tested within an adaptation of Protection Motivation theory (PMT). Participants evaluated text descriptions of four products described as: having an unpleasant bitter taste (Natural-FF); having 'additives' to reduce bitterness (Sweetened-FF); being genetically modified to enhance function (GM-FF) and Supplements. Participants were recruited as being of high and low perceived vulnerability to memory failure. In total, 290 middle-aged consumers (aged 40-60 years) participated in the study. Motivations to consume the GM-FF were the lowest. There were gender differences between intention to consume the supplements, Natural-FF and Sweetened-FF and product differences within genders. Women were less favourable than men in their attitudes towards genetic modification in general. Regression analyses indicated that PM predictors of intention to consume functional foods or supplements explained 59-63% of the variance (R2). Overall, perceived 'efficacy' (of the behaviour) and self-efficacy were the most important predictors of intentions to consume.

The human pregnane X receptor: genomic structure and identification and functional characterization of natural allelic variants.

The pregnane X receptor (PXR)/steroid and xenobiotic receptor (SXR) transcriptionally activates cytochrome P4503A4 (CYP3A4) when ligand activated by endobiotics and xenobiotics. We cloned the human PXR gene and analysed the sequence in DNAs of individuals whose CYP3A phenotype was known. The PXR gene spans 35 kb, contains nine exons, and mapped to chromosome 13q11-13. Thirty-eight single nucleotide polymorphisms (SNPs) were identified including six SNPs in the coding region. Three of the coding SNPs are non-synonymous creating new PXR alleles [PXR*2, P27S (79C to T); PXR*3, G36R (106G to A); and PXR*4, R122Q (4321G to A)]. The frequency of PXR*2 was 0.20 in African Americans and was never found in Caucasians. Hepatic expression of CYP3A4 protein was not significantly different between African Americans homozygous for PXR*1 compared to those with one PXR*2 allele. PXR*4 was a rare variant found in only one Caucasian person. Homology modelling suggested that R122Q, (PXR*4) is a direct DNA contact site variation in the third alpha-helix in the DNA binding domain. Compared with PXR*1, and variants PXR*2 and PXR*3, only the variant PXR*4 protein had significantly decreased affinity for the PXR binding sequence in electromobility shift assays and attenuated ligand activation of the CYP3A4 reporter plasmids in transient transfection assays. However, the person heterozygous for PXR*4 is normal for CYP3A4 metabolism phenotype. The relevance of each of the 38 PXR SNPs identified in DNA of individuals whose CYP3A basal and rifampin-inducible CYP3A4 expression was determined in vivo and/or in vitro was demonstrated by univariate statistical analysis. Because ligand activation of PXR and upregulation of a system of drug detoxification genes are major determinants of drug interactions, it will now be useful to extend this work to determine the association of these common PXR SNPs to human variation in induction of other drug detoxification gene targets.

DNA microarray reveals changes in gene expression of shear stressed human umbilical vein endothelial cells.

Using DNA microarray screening (GeneFilter 211, Research Genetics, Huntsville, AL) of mRNA from primary human umbilical vein endothelial cells (HUVEC), we identified 52 genes with significantly altered expression under shear stress [25 dynes/cm(2) for 6 or 24 h (1 dyne = 10 microN), compared with matched stationary controls]; including several genes not heretofore recognized to be shear stress responsive. We examined mRNA expression of nine genes by Northern blot analysis, which confirmed the results obtained on DNA microarrays. Thirty-two genes were up-regulated (by more than 2-fold), the most enhanced being cytochromes P450 1A1 and 1B1, zinc finger protein EZF/GKLF, glucocorticoid-induced leucine zipper protein, argininosuccinate synthase, and human prostaglandin transporter. Most dramatically decreased (by more than 2-fold) were connective tissue growth factor, endothelin-1, monocyte chemotactic protein-1, and spermidine/spermine N1-acetyltransferase. The changes observed suggest several potential mechanisms for increased NO production under shear stress in endothelial cells.

Transgenic pigs as bioreactors: a comparison of gamma-carboxylation of glutamic acid in recombinant human protein C and factor IX by the mammary gland.

The mammary gland of transgenic livestock can be used as a bioreactor for producing complex therapeutic proteins. However, the capacity for making a given post-translational modification upon any given polypeptide is uncertain. For example, the efficiency of gamma-carboxylation of glutamic acid in the amino terminal regions of recombinant human protein C (rhPC) and recombinant human Factor IX (rhFIX) is different at similar expression levels. At an expression level of about 200 microg/ml in the milk of transgenic pigs, rhFIX is highly gamma-carboxylated as indicated by pro-coagulant activity and amino acid sequencing. However, only about 20-35% of rhPC has a native, gamma-carboxyglutamic acid-dependent conformation and anti-coagulant activity. Thus, this work provides an example of apparent differences in substrate specificity between two homologous proteins to the endogenous carboxylase of porcine mammary epithelium which leads to varying degrees of post-translational modification.

Construction of a 1.5-Mb bacterial artificial chromosome contig in Xp11.23, a region of high gene content.

To generate sequence-ready templates for the gene-rich Xp11.23 region, we have constructed a 1.5-Mb bacterial artificial chromosome (BAC) contig spanning the interval between the DNA markers OATL1 and DXS255. The contig includes 28 BACs, ranging in size from 58 to 258 kb with an average size of 135 kb, which provide 2.5-fold coverage of the region. The BAC contig was constructed based entirely on the content of 40 DNA markers from a previously established YAC contig and 11 new markers developed from BAC-end DNA sequences, 4 of which were required to close gaps in the map. There was no evidence of rearrangement, instability, or chimerism in any of the BAC clones. The BAC cloning system appears to provide robust and total physical coverage of this gene-rich region with clones that are suitable for DNA sequencing.

Phenotypic and genotypic stability of multiple lines of transgenic pigs expressing recombinant human protein C.

The genotypic and phenotypic stability of four lines of transgenic pigs expressing recombinant human protein C in milk was examined. Two lines were established with a construct consisting of a 2.6 kb mouse WAP promoter and a 9.4 kb human protein C genomic DNA. Two lines were established with another construct consisting of a 4.1 kb mouse WAP promoter and a 9.4 kb human protein C genomic DNA. Genotypic stability was measured by transgene copy number transmission. Outbred offspring having a single transgene integration locus were established from a founder having three independent, multicopy loci. Phenotypic stability over multiple lactations was defined by the combination of recombinant human protein C expression levels and the isoform signature of recombinant human protein C in western blots. Both cDNA and genomic human protein C transgenes gave similar ranges of expression levels of about 100-1800 micrograms ml-1. Within a given outbred lineage having a single loci for the cDNA transgene, the expression levels ranged between 100-400 micrograms ml-1. Western blots of reduced recombinant protein C revealed that single chain content was not dependent on expression level and was consistent within each transgenic line, but varied between transgenic lines. This suggests that native swine genetics may play a role in selection of production herds with optimal post-translational proteolytic processing capability. Although swine are not conventional dairy livestock, it is agreed that the short generation times, multiple offspring per litter, stable paternal transmission of the transgene, and milk production capabilities of swine offer distinct advantages over conventional dairy livestock for the establishment of a herd producing a therapeutic recombinant protein.

Transgene detection during early murine embryonic development after pronuclear microinjection.

The polymerase chain reaction (PCR) technique was used to detect a whey acidic protein (WAP) gene and transgene presence in mouse ova cultured to various stages of development after pronuclear microinjection at the one-cell stage. The PCR technique detected an endogenous 442 bp WAP DNA sequence in 78% of one-cell, 88% of two-cell and 94% of four-cell ova, and in 95% of morulae and 97% of blastocysts. The heterologous WAP-human protein C transgene was detected in 88% of one-cell, 88% of two-cell and 44% of four-cell ova, and in 40% of morulae and 29% of blastocysts. For comparison, the integration frequency for transgenic mouse production using the same DNA construct was 22%. After five days of in vitro culture, embryos that were either developmentally arrested or fragmented were tested for the presence of the transgene. The injected construct was detected in 83% of arrested one-cell, 85% of arrested two-cell, and 85% of fragmented ova. In culture, only 28% of zygotes microinjected with DNA developed to the blastocysts stage compared to 74% of noninjected zygotes, while 63% of zygotes developed to the blastocyst stage after injection of buffer alone. Pronuclear injection of the transgene at concentrations of 1.5, 15 and 50 micrograms ml-1 resulted in 28, 11 and 9% development to blastocysts and 29, 86 and 88% transgene detection, respectively. Transgene detection was 85, 96 and 97% in degenerate embryos at the respective doses of DNA. These data show that pronuclear microinjection of the transgene is detrimental to subsequent embryonic development.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of time of gene microinjection on development and DNA detection frequency in bovine embryos.

The effect of DNA microinjection at various times after in vitro insemination on DNA detection and survival rates of bovine embryos was investigated. Oocytes were inseminated 24 h after maturation with frozen/thawed semen prepared with a Percoll separation procedure. At 11, 15 and 19 h after insemination, embryos were centrifuged to visualize pronuclei and microinjected with a murine whey acidic protein-human protein C genomic DNA construct. After culture for 7 days on Buffalo Rat Liver cells, embryos were assessed for stage of development and assayed for the presence of the transgene by polymerase chain reaction. Of zygotes in the 11 h after insemination treatment, 16% (25/152) of non-injected and 7% (11/161) of injected embryos developed to the morula or blastocyst stage. Comparable development of non-injected and injected embryos treated at 15 h after insemination was 15% (23/158) and 4% (6/159) and treated at 19 h after insemination was 14% (23/162) and 1% (1/165), respectively. Development of injected embryos was greater (p < 0.05) when injection was performed at 11 h after insemination compared to 19 h after insemination. Development of non-injected embryos was greater (p < 0.01) than that of injected embryos. There was no difference in transgene detection frequency in embryos of all developmental states between treatments (53% at 11; 50% at 15; 48% at 19 h after insemination). Injected embryos testing positive for the presence of the transgene exhibited increased development over negative embryos (p < 0.01). Greater development efficiencies can be obtained in microinjected bovine embryos when injection is performed early in pronuclear formation.

Effects of time of deoxyribonucleic acid microinjection on gene detection and in vitro development of bovine embryos.

In vivo fertilized embryos were surgically collected from superovulated dairy cows to evaluate microinjection on embryo development and utilized the polymerase chain reaction technique for selection of transgenic embryos. Seventy-two percent of the embryos with visible pronuclei or nuclei were microinjected with DNA, and the remaining 28% served as uninjected controls. All embryos were cocultured with bovine oviductal epithelial cells. Mean final development scores of embryos within the same initial cell stage at collection were unaffected by microinjection. After 144 h of culture, 45% of the microinjected embryos developed to the morula or blastocyst stage. The transgene was detected in 50, 10, and 9% of demimorulae from embryos microinjected at the 1-, 2-, and 4-cell stages. Frequency of transgene detection was higher in morulae from 1-cell embryos than in morulae from 2- and 4-cell embryos. Use of in vitro coculture, embryo bisection, and polymerase chain reaction technique facilitated selection of bovine embryos that carried the transgene.

Ovulation rate, zygote recovery and follicular populations in FSH-superovulated goats treated with PGF(2alpha) and/or GnRH.

Follicular development and ovulation were examined in superovulated Nubian and Nubian-cross dairy goats following prostaglandin F(2alpha) (PGF(2alpha)) and/or gonadotropin releasing hormone (GnRH) treatment. Estrus was synchronized with Synchromate-B((R)) implants. Superovulation was induced with follicle stimulating hormone (FSH) and augmented with GnRH and/or PGF(2alpha). The PGF(2alpha) treatment was administered on Day 2 of superovulation. Implants were removed from all goats on Day 3 of superovulation. The GnRH treatment was administered 24 h after implant removal. All does were exposed to fertile males for 48 h at the time of GnRH injection. Surgical embryo recovery and ovarian response evaluation were conducted 64 to 78.5 h after implant removal. The number of ovulations was higher with GnRH treatment (18.5 +/- 7; x +/- SEM) than that in the controls (5.3 +/- 4.1; P < 0.05). There were fewer follicles in the GnRH-treated does than in the untreated does (10.9 +/- 2.9 vs 22.1 +/- 3.2; P < 0.05). The number of follicles smaller than 4 mm in diameter (5.8 +/- 0.8) did not differ between treatments. The GnRH-treated does had fewer 4- to 8-mm follicles (4.2 +/- 2.0 vs 9.1 +/- 1.6; P < 0.05) and fewer follicles larger than 8 mm (0.7 +/- 1.4 vs 7.3 +/- 1.6; P < 0.01) than the controls. Predicted times for 1- and 2-cell embryo recoveries were 68.5 and 73.7 h following implant removal, respectively. This study demonstrates that GnRH is an effective supplement used with FSH superovulation regimens in dairy goats. Moreover, GnRH provides for enhanced early embryo collection for DNA microinjection studies.

Gene transfer efficiency during gestation and the influence of co-transfer of non-manipulated embryos on production of transgenic mice.

Litter size of DNA microinjected zygotes is lower than for non-manipulated zygotes. The rate of embryonic and fetal survival in early, mid and late gestation was determined to assess whether DNA integration was responsible for embryonic losses. Also, the effect of including non-microinjected embryos with injected embryos on pregnancy rate and transgenic pup production was determined. In Experiment 1, one-cell embryos from immature CD-1 mice were microinjected with a whey acidic protein promoter-human protein C gene construct. One hour after microinjection embryos were transferred to pseudopregnant recipients (45 transfers of 30 embryos each). Fifteen recipients were sacrificed on day 4, 12 and 18 of gestation and the embryos/fetuses analysed for the transgene. The percentage of embryos or fetuses that were positive for the transgene was not significantly different at any day. However, the number of viable embryos at day 4 was significantly greater than fetuses on days 12 or 18. In addition, a high degree of mosaicism was observed in day 18 fetuses and placentae recovered. In Experiment 2, one-cell embryos from CD-1 mice were microinjected and co-transferred with non-manipulated embryos (C57BL/6). Pregnancy rate and the total number of pups born were improved by addition of non-injected embryos. However, the number of transgenic mice produced was similar whether non-injected embryos were included or not. There were 32.2% (15/46) transgenic pups when 0 non-injected embryos were transferred compared with 15.1% (13/86) transgenic pups when 4 or 8 non-injected embryos were added to the transfers. In summary, a high degree of embryonic and fetal mortality occurs among microinjected embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

High-level expression of a heterologous protein in the milk of transgenic swine using the cDNA encoding human protein C.

Transgenic pigs were generated that produced human protein C in their milk at up to 1 g/liter. The gene construct was a fusion gene consisting of the cDNA for human protein C inserted into the first exon of the mouse whey acidic protein gene. These results demonstrate that the mouse whey acidic protein gene contains regulatory elements that can direct cDNA expression at high levels in the pig mammary gland. Recombinant human protein C that was produced at about 380 micrograms/ml per hr in transgenic pig milk possessed anticoagulant activity that was equivalent to that of protein C derived from human plasma. These studies provide evidence that gamma-carboxylation can occur at high levels in the mammary gland of a pig.

Acute large-bowel pseudo-obstruction.

The clinical and radiological features of acute large-bowel pseudo-obstruction occurring in 13 patients over a 7-year period are reviewed. Clinical features included atypical signs and symptoms of large-bowel obstruction and serious concomitant illness, including trauma in 10. The predominant radiological features were gross colonic dilatation, scant fluid levels, a gradual transition to collapsed bowel and a normal gas and faecal pattern in the rectum. Correct diagnosis was established by plain film and/or barium enema examination in the majority of cases (nine out of the 13). In the remaining four cases the diagnosis was made at laparotomy, although review of the radiographs suggested that the correct diagnosis could have been made pre-operatively in three. Instant barium enema is recommended in doubtful cases to rule out distal obstruction. Prompt recognition of the condition, with daily monitoring and conservative management, should eliminate unnecessary surgery and minimise the risk of caecal perforation.

Resection for pancreatitis in patients with pancreas divisum.

Pancreas divisum is an anatomic duct variant, which may predispose to pancreatitis. Most patients are managed conservatively, but some patients justify attempts to improve drainage. The correct surgical approach is not yet established, and there has been no series published concerning pancreatic resection in this context. A 6-year experience with resection performed in 14 patients with severe pain is reported. There were no operative deaths, and 11 patients had good pain relief; steatorrhea developed in two patients and diabetes in one. The hypothesis that pancreas divisum may cause pancreatitis is supported by examination of resection specimens after pancreaticoduodenectomy; the dorsal part showed chronic pancreatitis and the ventral portion was normal.