The Context Dependency of the Self-Report Version of the Strength and Difficulties Questionnaire (SDQ): A Cross-Sectional Study between Two Administration Settings

Background

The Strength and Difficulties Questionnaire (SDQ) is a screening instrument for psychosocial problems in children and adolescents, which is applied in “individual” and “collective” settings. Assessment in the individual setting is confidential for clinical applications, such as preventive child healthcare, while assessment in the collective setting is anonymous and applied in (epidemiological) research. Due to administration differences between the settings it remains unclear whether results and conclusions actually can be used interchangeably. This study therefore aims to investigate whether the SDQ is invariant across settings.

Methods

Two independent samples were retrieved (mean age = 14.07 years), one from an individual setting (N = 6,594) and one from a collective setting (N = 4,613). The SDQ was administered in the second year of secondary school in both settings. Samples come from the same socio-geographic population in the Netherlands.

Results

Confirmatory factor analysis showed that the SDQ was measurement invariant/equivalent across settings and gender. On average, children in the individual setting scored lower on total difficulties (mean difference = 2.05) and the psychosocial problems subscales compared to those in the collective setting. This was also reflected in the cut-off points for caseness, defined by the 90th percentiles, which were lower in the individual setting. Using cut-off points from the collective in the individual setting therefore resulted in a small number of cases, 2 to 3%, while ∼10% is expected.

Conclusion

The SDQ has the same connotation across the individual and collective setting. The observed structural differences regarding the mean scores, however, undermine the validity of the cross-use of absolute SDQ-scores between these settings. Applying cut-off scores from the collective setting in the individual setting could, therefore, result in invalid conclusions and potential misuse of the instrument. To correctly apply cut-off scores these should be retrieved from the applied setting.     

Between nurture and nature: the shifting determinants of female fertility in Danish twin cohorts

Behaviors related to fertility constitute primary candidates for investigating the relevance of evolutionary influences and biological dispositions on contemporary human behaviors. Using female Danish twin cohorts born 1870-1968, we document important transformations in the relative contributions of "nurture" and "nature" to within-cohort variations in early and complete fertility, and we point toward a systematic relation between the socioeconomic context of cohorts and the relevance of genetic and shared environmental factors. This transformation is most striking for early fertility where genetic factors strengthen over time and are consistent with up to 50 percent of the variation in early fertility in most recent cohorts. Understanding this emerging relevance of genetic factors is of central importance because early fertility constitutes an important determinant of complete fertility levels in low-fertility societies, and because teenage motherhood and early childbearing are often associated with negative life-cycle consequences. Moreover, our results emphasize the need for socially and contextually informed analyses of nature and nurture that allow both factors to influence human reproductive behavior over time.     

Telomeres and telomerase: more than the end of the line

Early studies of telomerase suggested that telomeres are maintained by an elegant but relatively simple and highly conserved mechanism of telomerase-mediated replication. As we learn more, it has become clear that the mechanism is elegant but not as simple as first thought. It is also evident that, although many species use similar, sometimes identical, DNA sequences for telomeres, these species express their own individuality in the way they regulate these sequences and, perhaps, in the additional tasks that they have imposed on their telomeric DNA. The striking similarities between telomeres in different species have revealed much about chromosome ends; the differences are proving to be equally informative. In addition to the differences between species that use telomerase, there are also a few exceptional organisms with atypical telomeres for which no telomerase activity has been detected. This review addresses recent studies, the insights they offer, and, perhaps more importantly, the questions they raise. Received: 14 January 1999 / Accepted: 15 January 1999     

Recombination and loss of complementation: a more than two-fold cost for parthenogenesis

Certain types of asexual reproduction lead to loss of complementation, that is unmasking of recessive deleterious alleles. A theoretical measure of this loss is calculated for apomixis, automixis and endomitosis in the cases of diploidy and polyploidy. The effect of the consequent unmasking of deleterious recessive mutations on fitness is also calculated. Results show that, depending on the number of lethal equivalents and on the frequency of recombination, the cost produced by loss of complementation after few generations of asexual reproduction may be greater than the two-fold cost of meiosis. Maintaining complementation may, therefore, provide a general short-term advantage for sexual reproduction. Apomixis can replace sexual reproduction under a wide range of parameters only if it is associated with triploidy or tetraploidy, which is consistent with our knowledge of the distribution of apomixis.     

Evidence for more than one pathway in the formation of purine deoxyribonucleotides

The biosynthesis of purine deoxyribonucleotides was studied in the context of general purine nucleotide metabolism in the chick with the aid of radioactive nucleic acid precursors. Our results showed that in chick liver and intestine, the nucleoside phosphate reductase system so firmly established in E. coli [1] and L. leichmanni [2] is not exclusively responsible for the biosynthesis of purine deoxyribonucleotides.     

Unique properties of polyphenol stilbenes in the brain: more than direct antioxidant actions; gene/protein regulatory activity

The 'French Paradox' has been typically associated with moderate consumption of wine, especially red wine. A polyphenol 3,4',5-trihydroxy-trans-stilbene (a member of the non-flavonoids family), better known as resveratrol, has been purported to have many health benefits. A number of these valuable properties have been attributed to its intrinsic antioxidant capabilities, although the potential level of resveratrol in the circulation is likely not enough to neutralize free radical scavenging. The brain and the heart are uniquely vulnerable to hypoxic conditions and oxidative stress injuries. Recently, evidence suggests that resveratrol could act as a signaling molecule within tissues and cells to modulate the expression of genes and proteins. Stimulation of such proteins and enzymes could explain some the intracellular antioxidative properties. The modulation of genes could suffice as an explanation of some of resveratrol's cytoprotective actions, as well as its influence on blood flow, cell death, and inflammatory cascades. Resveratrol stimulation of the expression of heme oxygenase is one example. Increased heme oxygenase activity has led to significant protection against models of in vitro and in vivo oxidative stress injury. Resveratrol could provide cellular resistance against insults; although more work is necessary before it is prescribed as a potential prophylactic in models of either acute or chronic conditions, such as stroke, amyotrophic lateral sclerosis, Parkinson, Alzheimer, and a variety of age-related vascular disorders.     

Seeing more than meets the eye: processing of illusory contours in animals

This review article illustrates that mammals, birds and insects are able to perceive illusory contours. Illusory contours lack a physical counterpart, but monkeys, cats, owls and bees perceive them as if they were real borders. In all of these species, a neural correlate for such perceptual completion phenomena has been described. The robustness of neuronal responses and the abundance of cells argue that such neurons might indeed represent a neural correlate for illusory contour perception. The internal state of an animal subject (i.e., alert and behaving) seems to be an important factor when correlating neural activity with perceptual phenomena. The fact that the neural network necessary for illusory contour perception has been found in relatively early visual brain areas in all tested animals suggests that bottom-up processing is largely sufficient to explain such perceptual abilities. However, recent findings in monkeys indicate that feedback loops within the visual system may provide additional modulation. The detection of illusory contours by independently evolved visual systems argues that processing of edges in the absence of contrast gradients reflects fundamental visual constraints and not just an artifact of visual processing.     

Psychometric Properties of the Eating Disorder Examination Questionnaire (EDE-Q) and Norms for Rural and Urban Adolescent Males and Females in Mexico

Aims

To contribute new evidence to the controversy about the factor structure of the Eating Disorder Examination Questionnaire (EDE-Q) and to provide, for the first time, norms based on a large adolescent Mexican community sample, regarding sex and area of residence (urban/rural).

Methods

A total of 2928 schoolchildren (1544 females and 1384 males) aged 11-18 were assessed with the EDE-Q and other disordered eating questionnaire measures.

Results

Confirmatory factor analysis of the attitudinal items of the EDE-Q did not support the four theorized subscales, and a two-factor solution, Restraint and Eating-Shape-Weight concern, showed better fit than the other models examined (RMSEA = .054); measurement invariance for this two-factor model across sex and area of residence was found. Satisfactory internal consistency (ω ≥ .80) and two-week test-retest reliability (ICCa ≥ .84; κ ≥ .56), and evidence for convergent validity with external measures was obtained. The highest attitudinal EDE-Q scores were found for urban females and the lowest scores were found for rural males, whereas the occurrence of key eating disorder behavioural features and compensatory behaviours was similar in both areas of residence.

Conclusions

This study reveals satisfactory psychometric properties and provides population norms of the EDE-Q, which may help clinicians and researchers to interpret the EDE-Q scores of adolescents from urban and rural areas in Mexico.     

Defining protein expression in the urothelium: a problem of more than transitional interest

The transitional epithelium of the bladder, the urothelium, is a challenging tissue to study due to its fragility, complex cellular makeup, stratified composition, and intimate connections to both neural and connective tissue elements. With the increasing focus on the urothelium as a mechanosensory tissue with complex autocrine and paracrine signaling activities, there have arisen a number of unresolved controversies in the urothelial literature regarding whether certain important sensory and signaling proteins are expressed by the urothelium. Prominent examples of this include the transient receptor potential (TRP) family member TRPV1 and the purinergic receptor P2X(3). The problem is more than one of scientific bookkeeping since studies utilizing genetic models (primarily knockout mice) claim additional credibility for urothelial functions when phenotypes are discovered. Furthermore, both of the above-mentioned receptors are important therapeutic targets for various bladder disorders including inflammatory and neuropathic pain. The reasons for the confusion about urothelial expression are manifold, but they likely include low expression levels in some cases, poor specificity of antibodies (sometimes lacking adequate controls), the presence of nonurothelial cells resident within the urothelium, and the fact that the urothelium is particularly prone to aspecific adsorption of antibodies. In this review, we attempt to summarize some of the pitfalls with currently accepted practices in this regard, as well as to describe a set of guidelines which will improve the reliability of conclusions related to urothelial expression. It is hoped that this will be of value to investigators studying the urothelium, to those attempting to interpret conflicts in the literature, and hopefully also those charged with reviewing unpublished work. These recommendations will outline a set of "baseline" and "best practice" guidelines by which both researchers and reviewers will be able to evaluate the evidence presented.     

Organic matter concentrations and textural properties of muds from different depths in four fish ponds

Percentages of small particles and organic matter in pond muds increased along transects from shallow to deep water in four fish ponds which had never been drained. Gradients in texture and organic matter were similar to those reported for nearby ponds which had been drained periodically.Research supported by Hatch Project Alabama No. 398.     

On the structure and function of apolipoproteins: more than a family of lipid-binding proteins

Exchangeable apolipoproteins have been the subject of intense biomedical investigation for decades. However, only in recent years the elucidation of the three-dimensional structure reported for several members of the apolipoprotein family has provided insights into their functions at a molecular level for the first time. Moreover, the role of exchangeable apolipoproteins in several cellular events distinct from lipid metabolism has recently been described. This review summarizes these contributions, which have not only allowed the identification of the apolipoprotein domains that determine substrate binding specificity and/or affinity but also the plausible molecular mechanism(s) involved.     

Modularity and intra-floral integration in metameric organisms: plants are more than the sum of their parts

Within-individual variation in virtually every conceivable morphological and functional feature of reiterated structures is a pervasive feature of plant phenotypes. In particular, architectural effects, regular, repeatable patterns of intra-individual variation in form and function that are associated with position are nearly ubiquitous. Yet, flowers also are predicted to be highly integrated. For animal-pollinated plants, the coordination of multiple organs within each flower is required to achieve the complex functions of pollinator attraction and orientation, pollen donation and pollen receipt. To the extent that pollinators may select for multiple independent functions, phenotypic integration within flowers may also be modular. That is, subsets of floral structures may be integrated but vary independently of other subsets of structures that are themselves integrated. How can phenotypic integration and modularity be understood within the context of architectural effects? This essay reviews recent research on patterns of floral integration and modularity and explores the potential for spatial and temporal changes in the selective environment of individual flowers to result in positional variation in patterns of morphological integration.     

Energetic contributions of four arginines to phosphate-binding in thymidylate synthase are more than additive and depend on optimization of "effective charge balance"

In thymidylate synthase, four conserved arginines provide two hydrogen bonds each to the oxygens of the phosphate group of the substrate, 2'-deoxyuridine-5'-monophosphate. Of these, R23, R178, and R179 are far removed from the site of methyl transfer and contribute to catalysis solely through binding and orientation of ligands. These arginines can be substituted by other residues, while still retaining more than 1% activity of the wild-type enzyme. We compared the kinetics and determined the crystal structures of dUMP complexes of three of the most active, uncharged single mutants of these arginines, R23I, R178T, and R179T, and of double mutants (R23I, R179T) and (R178T, R179T). The dramatically higher K(m) for R178T compared to the other two single mutants arises from the effects of R178 substitution on the orientation of dUMP; 10-15-fold increases in for R23I and R178T reflect the role of these residues in stabilizing the closed conformation of TS in ternary complexes. The free energy for productive dUMP binding, DeltaG(S), increases by at least 1 kcal/mol for each mutant, even when dUMP orientation and mobility in the crystal structure is the same as in wild-type enzyme. Thus, the four arginines do not contribute excess positive charge to the PO(4)(-2) binding site; rather, they ideally complement the charge and geometry of the phosphate moiety. More-than-additive increases in DeltaG(S) seen in the double mutants are consistent with quadratic increases in DeltaG(S) predicted for deviations from ideal electrostatic interactions and may also reflect cooperative binding of the arginines to the phosphate oxygens.     

Marfan syndrome: No evidence for heterogeneity in different populations, and more precise mapping of the gene

Marfan syndrome is a dominantly inherited connective tissue disorder with manifestations in the cardiovascular, ocular, and skeletal systems. The diagnosis is hampered by both high variability in the phenotypic expression and late manifestation of symptoms. The cause of Marfan syndrome remains unknown, but our group has recently reported the genetic linkage of Marfan syndrome to a polymorphic marker on chromosome 15. To analyze the possible heterogeneity behind Marfan syndrome, we have performed linkage analyses for four chromosome 15 markers in 17 families from five different populations: Scottish, English, Swiss, American, and Finnish. By combining the linkage data of all the studied families into a LINKMAP analysis we obtained a maximal LOD score of 11.2, which maps the Marfan syndrome locus between D15S25 and D15S45 on the long arm of chromosome 15. The data reveal no evidence for genetic heterogeneity behind Marfan syndrome and provide us with a more precise location of both the Marfan syndrome locus and flanking markers. This information will provide the basis for the DNA diagnostics of Marfan syndrome in the future.     

Mexican copalchis of the Rubiaceae family: more than a century of pharmacological and chemical investigations

Phytochemistry Reviews - The term copalchi has been used in the scientific literature to define a group of plants of the Rubiaceae and Euphorbiaceae families with extremely bitter stem-barks,...