Initial investigation of associations between feeding practices, eating behaviours, and weight status in Vietnamese children using modified questionnaires.

AIMS: This cross-sectional study aims to extend the preliminary validation of the Feeding Practices and Structure Questionnaire (FPSQ) and Children's Eating Behaviour Questionnaire (CEBQ) in the Vietnamese context by examining associations between maternal feeding practices, child eating behaviours, and child weight status. METHODS: Modified versions of the FPSQ and CEBQ were used to measure maternal feeding practices and child eating behaviours, respectively, in a sample of Vietnamese mothers of children within the age range of two to five years (n = 100). Children's weight-for-height z-scores (WHZs) were calculated using weight and height measurements obtained by clinicians. Pearson's correlation coefficients were used to examine bivariate associations between maternal feeding practices, child eating behaviours, and child WHZs. Significant variables were then entered into a multivariable regression model. RESULTS: Child WHZs were associated with maternal persuasive feeding, and child slowness in eating, enjoyment of food/food responsiveness, and emotional undereating, but in multivariable regression analysis, only persuasive feeding (ß = -0.44, p = 0.027) and slowness in eating (ß = -0.39, p = 0.036) contributed significantly to the model. CONCLUSIONS: The findings provide some evidence of construct validity for the modified questionnaires. Potential implications of dietary-related behaviours on weight status in preschool-aged children in Viet Nam are evident. However, further validation and analysis in larger datasets must be undertaken in order to examine these associations with increased certainty.

Preliminary exploration of the use of the Children's Eating Behaviour Questionnaire (CEBQ) and Feeding Practices and Structure Questionnaire (FPSQ) in Vietnamese mothers.

OBJECTIVE: This preliminary pilot study aims to explore the use of the Feeding Practices and Structure Questionnaire (FPSQ) and Children's Eating Behaviour Question (CEBQ) in a sample of Vietnamese mothers. SUBJECTS/METHODS: Cross-sectional data from the FPSQ and CEBQ were collected from a convenience sample of mothers (n = 102) who attended the Ho Chi Minh City Nutrition Centre in Viet Nam. Mothers had at least one child aged 2-5 years. The reliability of the questionnaire subscales was tested using Cronbach's alpha coefficients. Face validity was assessed using dialogue from a translation-back-translation procedure undertaken by an expert committee, and cognitive interviews conducted in a subsample of mothers (n = 6). Based on these findings, exploratory factor analyses (EFAs) were performed to assess the underlying structures of both questionnaires in this sample. RESULTS: Cronbach's alpha coefficients for the original questionnaires ranged from 0.23 to 0.92. Limitations in translation and comprehension of items surfaced, warranting modifications of the questionnaires, which were subsequently examined using EFA. EFA of the FPSQ and CEBQ revealed a six-factor structure with 23 items, and a six-factor structure with 27 items, respectively, which were interpretable solutions for this sample. Cronbach's alpha coefficients were >0.70 for all subscales in the revised questionnaires. CONCLUSIONS: Modified versions of the FPSQ and CEBQ are proposed for use in Viet Nam. However, prior to their use, further reliability and validity testing must be undertaken in larger samples, including assessment of test-retest reliability and construct validity, as well as confirmatory factor analysis to verify the proposed factor structures.

Conformation Analysis of Ferrocene and Decamethylferrocene via Full-Potential Modeling of XANES and XAFS Spectra.

Recent high-accuracy X-ray absorption measurements of the sandwich organometallics ferrocene (Fc) and decamethylferrocene (DmFc) at temperatures close to liquid helium are compared with new full-potential modeling of X-ray absorption fine structure (XAFS) covering the near-edge region (XANES) and above up to k = 7 Å(-1). The implementation of optimized calculations of the oscillatory part of the spectrum from the package FDMX allows detailed study of the spectra in regions of the photoelectron momentum most sensitive to differences in the molecular stereochemistry. For Fc and DmFc, this corresponds to the relative rotation of the cyclopentadienyl rings. When applied to high-accuracy XAFS of Fc and DmFc, the FDMX theory gives clear evidence for the eclipsed conformation for Fc and the staggered conformation for DmFc for frozen solutions at ca. 15 K. This represents the first clear experimental assignment of the solution structures of Fc and DmFc and reveals the potential of high-accuracy XAFS for structural analysis.

Structure determination from XAFS using high-accuracy measurements of x-ray mass attenuation coefficients of silver, 11 keV-28 keV, and development of an all-energies approach to local dynamical analysis of bond length, revealing variation of effective thermal contributions across the XAFS spectrum.

We use the x-ray extended range technique (XERT) to experimentally determine the mass attenuation coefficient of silver in the x-ray energy range 11 kev-28 kev including the silver K absorption edge. The results are accurate to better than 0.1%, permitting critical tests of atomic and solid state theory. This is one of the most accurate demonstrations of cross-platform accuracy in synchrotron studies thus far. We derive the mass absorption coefficients and the imaginary component of the form factor over this range. We apply conventional XAFS analytic techniques, extended to include error propagation and uncertainty, yielding bond lengths accurate to approximately 0.24% and thermal Debye-Waller parameters accurate to 30%. We then introduce the FDMX technique for accurate analysis of such data across the full XAFS spectrum, built on full-potential theory, yielding a bond length accuracy of order 0.1% and the demonstration that a single Debye parameter is inadequate and inconsistent across the XAFS range. Two effective Debye-Waller parameters are determined: a high-energy value based on the highly-correlated motion of bonded atoms (σ(DW) = 0.1413(21) Å), and an uncorrelated bulk value (σ(DW) = 0.1766(9) Å) in good agreement with that derived from (room-temperature) crystallography.

New consistency tests for high-accuracy measurements of X-ray mass attenuation coefficients by the X-ray extended-range technique.

An extension of the X-ray extended-range technique is described for measuring X-ray mass attenuation coefficients by introducing absolute measurement of a number of foils - the multiple independent foil technique. Illustrating the technique with the results of measurements for gold in the 38-50 keV energy range, it is shown that its use enables selection of the most uniform and well defined of available foils, leading to more accurate measurements; it allows one to test the consistency of independently measured absolute values of the mass attenuation coefficient with those obtained by the thickness transfer method; and it tests the linearity of the response of the counter and counting chain throughout the range of X-ray intensities encountered in a given experiment. In light of the results for gold, the strategy to be ideally employed in measuring absolute X-ray mass attenuation coefficients, X-ray absorption fine structure and related quantities is discussed.

Experimental measurement of the four-dimensional coherence function for an undulator x-ray source.

A full measurement of the four-dimensional coherence function from an undulator beam line is reported. The analysis is based on the observation that the data are consistent with a coherence function that is mathematically separable. The effective source size can be altered by changing the width of the exit slit, and the complete coherence function is presented for two settings. We find, to within experimental error, that the four-dimensional complex degree of coherence can be described as a real Gaussian function that depends only on the difference of the spatial coordinates.

Recovering the complete coherence function of a generalized Schell model field.

We prove that in the absence of phase singularities, a generalized Schell model partially coherent field is fully defined by its intensity in three planes. We discuss the implications of this result for the problem of characterizing wave fields.

Fresnel coherent diffractive imaging.

We present an x-ray coherent diffractive imaging experiment utilizing a nonplanar incident wave and demonstrate success by reconstructing a nonperiodic gold sample at 24 nm resolution. Favorable effects of the curved beam illumination are identified.

Synchrotron beam coherence: a spatially resolved measurement.

We report a precise and spatially resolved measurement of the complex degree of coherence of a one-dimensional 1.5-keV beam produced by a third-generation synchrotron source. The method of phase-space tomography is used, which requires only measurements of the x-ray intensity. We find that the field is statistically stationary to within experimental error, the correlations are very well approximated by a Gaussian distribution, and the measured coherence length is in excellent agreement with expectations.

X-ray mass attenuation coefficient of silicon: theory versus experiment.

We compare new experimental x-ray total mass attenuation coefficients of silicon obtained with the x-ray extended-range technique (XERT) from 5 to 20 keV with theoretical calculations and earlier experimental measurements over a 5 to 50 keV energy range. The accuracy of between 0.27% and 0.5% of the XERT data allows us to probe alternate atomic and solid state wave function calculations and to test dominant scattering mechanisms. Discrepancies between experimental results and theoretical computations of the order of 5% are discussed in detail. No single theoretical computation is currently able to reproduce the experimental results over the entire 5 to 50 keV energy range investigated.

The human homologue (PEG3) of the mouse paternally expressed gene 3 (Peg3) is maternally imprinted but not mutated in women with familial recurrent hydatidiform molar pregnancies.

OBJECTIVES: We mapped a locus for autosomal recessive molar pregnancies with biparental genomic contribution to chromosome 19q13.4 between D19S924 and D19S890. This 5-Mb region is homologous to proximal mouse chromosome 7 and contains a cluster of Krüppel-type zinc finger genes, including the human homologue of the mouse imprinted genes: the paternally expressed gene 3 (PEG3) and the maternally expressed Zim1 genes. We analyzed the PEG3 gene for mutations in women with familial recurrent hydatidiform moles and to determine its imprinting status in humans. METHODS: We used database searches and screened cDNA libraries to find the complete genomic structure of PEG3. Polymerase chain reaction (PCR) amplification and direct sequencing of coding exons and flanking introns were performed on genomic DNA from the affected women. Allele-specific methylation and expression were studied by methylation-sensitive Southern analysis of a 5' located CpG island and by reverse-transcription PCR of total lymphoblast-derived RNA of normal individuals who were informative for two expressed polymorphisms. RESULTS: We did not detect any mutations in the coding region of PEG3 in the affected women. We observed allele-specific methylation of the CpG island and expression from the paternal allele in two independent informative pedigrees. CONCLUSION: Consistent with the findings in the mouse, the human PEG3 gene is expressed from the paternal allele. Our data support that PEG3 is not mutated in women with familial recurrent hydatidiform moles, although mutations in the regulatory regions that might affect imprinting or transcriptional level of the gene could not be evaluated.

Influence of mutation type and X chromosome inactivation on Rett syndrome phenotypes.

We screened 71 sporadic and 7 familial Rett syndrome (RTT) patients for MECP2 mutations by direct sequencing and determined the pattern of X chromosome inactivation (XCI) in 39 RTT patients. We identified 23 different disease-causing MECP2 mutations in 54 of 71 (76%) sporadic patients and in 2 of 7 (29%) familial cases. We compared electrophysiological findings, cerebrospinal fluid neurochemistry, and 13 clinical characteristics between patients carrying missense mutations and those carrying truncating mutations. Thirty-one of 34 patients (91%) with classic RTT had random XCI. Nonrandom XCI was associated with milder phenotypes, including a mitigated classic RTT caused by a rare early truncating mutation. Patients with truncating mutations have a higher incidence of awake respiratory dysfunction and lower levels of cerebrospinal fluid homovanillic acid. Scoliosis is more common in patients with missense mutations. These data indicate that different MECP2 mutations have similar phenotypic consequences, and random XCI plays an important role in producing the full phenotypic spectrum of classic RTT. The association of early truncating mutations with nonrandom XCI, along with the fact that chimeric mice lacking methyl-CpG-binding protein 2 (MeCP2) function die during embryogenesis, supports the notion that RTT is caused by partial loss of MeCP2 function.

Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2.

Rett syndrome (RTT, MIM 312750) is a progressive neurodevelopmental disorder and one of the most common causes of mental retardation in females, with an incidence of 1 in 10,000-15,000 (ref. 2). Patients with classic RTT appear to develop normally until 6-18 months of age, then gradually lose speech and purposeful hand use, and develop microcephaly, seizures, autism, ataxia, intermittent hyperventilation and stereotypic hand movements. After initial regression, the condition stabilizes and patients usually survive into adulthood. As RTT occurs almost exclusively in females, it has been proposed that RTT is caused by an X-linked dominant mutation with lethality in hemizygous males. Previous exclusion mapping studies using RTT families mapped the locus to Xq28 (refs 6,9,10,11). Using a systematic gene screening approach, we have identified mutations in the gene (MECP2 ) encoding X-linked methyl-CpG-binding protein 2 (MeCP2) as the cause of some cases of RTT. MeCP2 selectively binds CpG dinucleotides in the mammalian genome and mediates transcriptional repression through interaction with histone deacetylase and the corepressor SIN3A (refs 12,13). In 5 of 21 sporadic patients, we found 3 de novo missense mutations in the region encoding the highly conserved methyl-binding domain (MBD) as well as a de novo frameshift and a de novo nonsense mutation, both of which disrupt the transcription repression domain (TRD). In two affected half-sisters of a RTT family, we found segregation of an additional missense mutation not detected in their obligate carrier mother. This suggests that the mother is a germline mosaic for this mutation. Our study reports the first disease-causing mutations in RTT and points to abnormal epigenetic regulation as the mechanism underlying the pathogenesis of RTT.