The RAF kinases activated by RAS GTPases regulate cell growth and division by signal transduction through the ERK cascade and mutations leading to constitutive activity are key drivers of human tumors, as are upstream activators including RAS and receptor tyrosine kinases. The development of first-generation RAF inhibitors, including vemurafenib (VEM) and dabrafenib led to initial excitement due to high response rates and profound regression of malignant melanomas carrying BRAF^V600E mutations. The excitement about these unprecedented response rates, however, was tempered by tumor unresponsiveness through both intrinsic and acquired drug-resistance mechanisms. In recent years much insight into the complexity of the RAS-RAF axis has been obtained and inactivation and signal transduction mechanisms indicate that RAF dimerization is a critical step in multiple cellular contexts and plays a key role in resistance. Both homo- and hetero-dimerization of BRAF and CRAF can modulate therapeutic response and disease progression in patients treated with ATP-competitive inhibitors and are therefore highly clinically significant. Ten years after the definition of the RAF dimer interface (DIF) by crystallography, this review focuses on the implications of RAF kinase dimerization in signal transduction and for drug development, both from a classical ATP-competitive standpoint and from the perspective of new therapeutic strategies including inhibiting dimer formation. A structural perspective of the DIF, how dimerization impacts inhibitor activation and the structure-based design of next-generation RAF kinase inhibitors with unique mechanisms of action is presented. We also discuss potential fields of application for DIF inhibitors, ranging from non-V600E oncoproteins and BRAF fusions to tumors driven by aberrant receptor tyrosine kinase or RAS signaling.

Perceived self-efficacy (SE) for eating fruit and vegetables (FV) is a key variable mediating FV change in interventions. This study applies item response modeling (IRM) to a fruit, juice and vegetable self-efficacy questionnaire (FVSEQ) previously validated with classical test theory (CTT) procedures. The 24-item (five-point Likert scale) FVSEQ was administered to 1578 fourth graders from 26 Houston schools. The IRM partial credit model indicated the five-point response options were not fully utilized. The questionnaire exhibited acceptable (>0.70) reliability except at the extremes of the SE scale. Differential item functioning (DIF) analyses revealed no response bias due to gender. However, DIF was detected by ethnic groups in 10 items. IRM of this scale expanded what was known from CTT methods in three ways: (i) areas of the scale were identified that were not as reliable, (ii) limitations were found in the response format and (c) areas of the SE scale levels were not measured. The FVSEQ can be improved by including items at the extreme levels of difficulty. DIF analyses identified areas where IRM can be useful to improve the functioning of measures.

BACKGROUND

Flebogamma 10% DIF represents an evolution of intravenous immune globulin from the previous 5% product to be administered at higher rates and with smaller infusion volumes. Pathogen safety is enhanced by the combination of multiple methods with different mechanisms of action.

OBJECTIVE

The objective of this study as to evaluate the efficacy, pharmacokinetics, and safety of Flebogamma 10% DIF for immunoglobulin replacement therapy in primary immunodeficiency diseases (PIDD).

METHODS

Flebogamma 10% DIF was administered to 46 subjects with well-defined PIDD at a dose of 300-600 mg/kg every 21-28 days for 12 months.

RESULTS

Serious bacterial infection rate was 0.025/subject/year. Half-life in serum of the administered IgG was approximately 35 days. No serious treatment-related adverse event (AE) occurred in any patient. Most of the potentially treatment-related AEs occurred during the infusion, accounting for 20% of the 601 infusions administered.

CONCLUSIONS

Flebogamma 10% DIF is efficacious and safe, has adequate pharmacokinetic properties, and is well-tolerated for the treatment of PIDD.

BACKGROUND

Flebogamma 5% dual inactivation and filtration (DIF) is the next generation of Flebogamma. Flebogamma was first licensed in 1992. The new preparation features additional viral inactivation and removal steps to enhance safety margins.

OBJECTIVE

The purpose of this study was to evaluate the efficacy, safety, and pharmacokinetics of Flebogamma 5% DIF for immunoglobulin replacement therapy in primary immunodeficiency diseases (PID).

METHODS

Flebogamma 5% DIF was administered at seven clinical sites to 46 subjects with well-defined primary immunodeficiency diseases at a dose of 300-600 mg/kg every 21-28 days for 12 months.

RESULTS

The calculated serious bacterial infection rate was 0.021/subject/year. The incidence of adverse events considered potentially related to Flebogamma 5% DIF during or within 72 h after completing an infusion was approximately 10%. The half-life in serum of the administered IgG was around 31 days.

CONCLUSIONS

Flebogamma 5% DIF is efficacious and safe, has adequate pharmacokinetic properties, is well-tolerated and maintains the profile of Flebogamma 5% for the treatment of primary humoral immunodeficiency diseases.

OBJECTIVE

To develop an oral health literacy instrument for Spanish-speaking adults, evaluate its psychometric properties, and determine its comparability to an English version.

METHODS

The Oral Health Literacy Assessment in Spanish (OHLA-S) and English (OHLA-E) are designed with a word recognition section and a comprehension section using the multiple-choice format developed by an expert panel. Validation of OHLA-S and OHLA-E involved comparing the instrument with other health literacy instruments in a sample of 201 Spanish-speaking and 204 English-speaking subjects. Comparability between Spanish and English versions was assessed by testing for differential item functioning (DIF) using item response theory.

RESULTS

We considered three OHLA-S scoring systems. Based on validity and reliability comparisons, 24 items were retained in the OHLA-S instrument. OHLA-S was correlated with another health literacy instrument, Spanish Test of Functional Health Literacy in Adults (P < 0.05). Significant correlations were also found between OHLA-S and years of schooling, oral health knowledge, overall health, and an understanding of written health-care materials (P < 0.05). OHLA-S displayed satisfactory reliability with a Cronbach Alpha of 0.70-0.80. DIF results suggested that OHLA-S and OHLA-E scores were not comparable at a given level of oral health literacy.

CONCLUSIONS

OHLA-S has acceptable reliability and validity. OHLA-S and OHLA-E are two different measurement tools and should not be used to compare oral health literacy between English- and Spanish-speaking populations.

OBJECTIVE

The role of thioredoxin reductase (TrxR) in tumorigenesis has made it an attractive anticancer target. A systematic approach for development of novel compounds as TrxR inhibitors is currently lacking. Structurally diversified TrxR inhibitors share in common electrophilic propensities for the sulfhydryl groups, among which include the Michael reaction acceptors containing an α,β-unsaturated carbonyl moiety. We aimed to identify features among structurally diversified Michael acceptor-based compounds that would yield a strong TrxR inhibitory character.

RESULTS

Structurally dissimilar Michael acceptor-based natural compounds such as isobutylamides, zerumbone, and shogaols (SGs) were found to possess a poor TrxR inhibitory activity, indicating that a sole Michael acceptor moiety was insufficient to produce TrxR inhibition. The 1,7-diphenyl-hept-3-en-5-one pharmacophore in 3-phenyl-3-SG, a novel SG analog that possessed comparable TrxR inhibitory and antiproliferative potencies as 6-SG, was modified to yield 1,5-diphenyl-pent-1-en-3-one (DPPen) and 1,3-diphenyl-pro-1-en-3-one (DPPro, also known as chalcone) pharmacophores. These Michael acceptor-centric pharmacophores, when substituted with the hydroxyl and fluorine groups, gave rise to analogs displaying a TrxR inhibitory character positively correlated to their antiproliferative potencies. Lead analogs 2,2'-diOH-5,5'-diF-DPPen and 2-OH-5-F-DPPro yielded a half-maximal TrxR inhibitory concentration of 9.1 and 10.5 μM, respectively, after 1-h incubation with recombinant rat TrxR, with the C-terminal selenocysteine residue found to be targeted.

METHODS

Identification of Michael acceptor-centric pharmacophores among diversified compounds demonstrates that a systematic approach to discover and develop Michael acceptor-based TrxR inhibitors is feasible.

CONCLUSIONS

A strong TrxR inhibitory character correlated to the antiproliferative potency is attributed to structural features that include an α,β-unsaturated carbonyl moiety centered in a DPPen or DPPro pharmacophore bearing hydroxyl and fluorine substitutions.

BACKGROUND

In the present study, we evaluated whether patients with panic disorder (PD) in complete remission were more alexithymic than normal controls.

METHODS

Fifty-two PD patients (both during the acute phase of the disorder and after at least 2 months of complete remission) and 52 age- and sex-matched normal subjects completed the Toronto Alexithymia Scale-20 and the Hamilton Rating Scales for Anxiety (Ham-A) and for Depression.

RESULTS

A higher rate of alexithymia was found in PD patients than in controls (3.8%) both during the acute phase (44.2%; p < 0.001) and after remission of the disorder (21.2%; p = 0.008). During remission, PD patients showed: (1) Ham-A scores significantly higher than controls (p < 0.001); (2) only an elevation of the 'difficulty in identifying feeling' (DIF) dimension of alexithymia, and (3) a positive relationship between Ham-A scores and DIF levels (p < 0.001).

CONCLUSIONS

After remission of panic attacks, phobic avoidance and anticipatory anxiety, PD patients are more alexithymic (even though the levels of alexithymia decreased after the resolution of the acute phase of PD) and anxious than controls. This finding might be explained by an overlap between cognitive aspects of PD and the DIF dimension of alexithymia, since alexithymic and anxious levels are positively related.

OBJECTIVE

Use Rasch analysis to examine the psychometric properties of the Oxford Knee Score (OKS), particularly in respect to unidimensionality, and consistency of item functioning before and after total knee replacement and across age and gender groups.

METHODS

The 12-item OKS was administered to 1,712 patients before the surgery, and 1,322 and 855 patients were administered the instrument repeatedly at the 6-month and 2-year postoperative assessments, respectively. Data were fitted to the Rasch partial credit model with the Winsteps program. Differential item functioning (DIF) analysis was performed, and fit statistics in combination with principal components analysis of the residuals were used to test the unidimensionality assumption. The fit criteria were set at 1.5 and 2.0 for infit mean-square (MNSQ) and outfit MNSQ, respectively.

RESULTS

At baseline, item difficulty ranged from -1.86 to 1.78 logits, and person measures had a mean+/-SD of -0.01+/-0.89. Misfit items were "limping" and "night pain" in preoperative data and "limping" and "kneeling" in postoperative data. After removing items limping and kneeling and recoding item night pain, none of the items misfit at each of the time points and there was stability of item difficulty ordering across time. In the modified OKS set, five items displayed DIF by age and three by gender.

CONCLUSIONS

The original OKS had adequate targeting and good coverage of knee severity levels in preoperative patients. The modified 10-item OKS data fit the Rasch model and had stable item difficulty ordering over time.

Pathological aggregation and mutation of the 43-kDa TAR DNA-binding protein (TDP-43) are strongly implicated in the pathogenesis amyotrophic lateral sclerosis and frontotemporal lobar degeneration. TDP-43 neurotoxicity has been extensively modeled in mice, zebrafish, Caenorhabditis elegans and Drosophila, where selective expression of TDP-43 in motoneurons led to paralysis and premature lethality. Through a genetic screen aimed to identify genetic modifiers of TDP-43, we found that the Drosophila dual leucine kinase Wallenda (Wnd) and its downstream kinases JNK and p38 influenced TDP-43 neurotoxicity. Reducing Wnd gene dosage or overexpressing its antagonist highwire partially rescued TDP-43-associated premature lethality. Downstream of Wnd, the JNK and p38 kinases played opposing roles in TDP-43-associated neurodegeneration. LOF alleles of the p38b gene as well as p38 inhibitors diminished TDP-43-associated premature lethality, whereas p38b GOF caused phenotypic worsening. In stark contrast, disruptive alleles of Basket (Bsk), the Drosophila homologue of JNK, exacerbated longevity shortening, whereas overexpression of Bsk extended lifespan. Among possible mechanisms, we found motoneuron-directed expression of TDP-43 elicited oxidative stress and innate immune gene activation that were exacerbated by p38 GOF and Bsk LOF, respectively. A key pathologic role for innate immunity in TDP-43-associated neurodegeneration was further supported by the finding that genetic suppression of the Toll/Dif and Imd/Relish inflammatory pathways dramatically extended lifespan of TDP-43 transgenic flies. We propose that oxidative stress and neuroinflammation are intrinsic components of TDP-43-associated neurodegeneration and that the balance between cytoprotective JNK and cytotoxic p38 signaling dictates phenotypic outcome to TDP-43 expression in Drosophila.

Many have argued that we may be able to extend life and improve human health through hormesis, the beneficial effects of low-level toxins and other stressors. But, studies of hormesis in model systems have not yet established whether stress-induced benefits are cost free, artifacts of inbreeding, or come with deleterious side effects. Here, we provide evidence that hormesis results in trade-offs with immunity. We find that a single topical dose of dead spores of the entomopathogenic fungus, Metarhizium robertsii, increases the longevity of the fruit fly, Drosophila melanogaster, without significant decreases in fecundity. We find that hormetic benefits of pathogen challenge are greater in lines that lack key components of antifungal immunity (Dif and Turandot M). And, in outbred fly lines, we find that topical pathogen challenge enhances both survival and fecundity, but reduces ability to fight off live infections. The results provide evidence that hormesis is manifested by stress-induced trade-offs with immunity, not cost-free benefits or artifacts of inbreeding. Our findings illuminate mechanisms underlying pathogen-induced life-history trade-offs, and indicate that reduced immune function may be an ironic side effect of the "elixirs of life."

The nuclear receptor ligand all-trans retinoic acid (ATRA) causes dramatic terminal differentiation of acute promyelocytic leukemia (APL) cells in vitro and in patients, but it is less active in other malignancies. However, downstream mediators of the effects of ATRA are not well understood. We used a cDNA microarray to search for ATRA-regulated genes in the APL cell line NB4 and found that ATRA regulated several members of the tumor necrosis factor (TNF) pathway. Here we show that TNF can synergize with ATRA to induce differentiation, showing monocytic characteristics more typical of differentiation mediated by TNF than by ATRA. ATRA and TNF can also induce differentiation of the non-APL cell line U937. Underlying this response was an increase in TNF-induced nuclear factor-kappaB (NF-kappaB) DNA binding within 2 hours in the presence of ATRA and activation of NF-kappaB DNA binding and transcriptional activity in response to ATRA alone within 48 hours of ATRA treatment. Furthermore, we found a synergistic induction of the NF-kappaB target genes BCL-3, Dif-2, and TNF receptor 2 (TNFR2) in response to the combination of TNF and ATRA. These genes have been previously shown to play a role in TNF signaling, and amplification of such genes may represent a mechanism whereby TNF and ATRA can act synergistically. We propose that ATRA can prime cancer cells for differentiation triggered by TNF and suggest that targeting the TNF pathway in combination with ATRA may represent a novel route to treat leukemias.

Depression often co-occurs in late-life in the context of declining cognitive functions, but it is not clear whether specific depression symptom dimensions are differentially associated with cognitive abilities.

The study sample comprised 3107 community-dwelling older adults from the Longitudinal Aging Study Amsterdam (LASA). We applied a Multiple Indicators Multiple Causes (MIMIC) model to examine the association between cognitive abilities and latent dimensions of the Center for Epidemiologic Studies Depression Scale (CES-D), while accounting for differential item functioning (DIF) due to age, gender and cognitive function levels.

A factor structure consisting of somatic symptoms, positive affect, depressed affect, and interpersonal difficulties fitted the data well. Higher levels of inductive reasoning were significantly associated with lower levels of depressed affect and somatic symptoms, whereas faster processing speed was significantly associated with lower levels of somatic symptoms. DIF due to age and gender was found, but the magnitude of the effects was small and did not alter substantive conclusions.

Due to the cross-sectional context of this investigation, the direction of influence between depression symptom levels and cognitive function levels cannot be established. Furthermore, findings are relevant to non-clinical populations, and they do not clarify whether certain DIF effects may be found only at high or low levels of depression.

Our findings suggest differential associations between late-life depression dimensions and cognitive abilities in old age, and point towards potential etiological mechanisms that may underline these associations. These findings carry implications for the prognosis of cognitive outcomes in depressed older adults.

OBJECTIVE

Alexithymia is characterized by a difficulty in identifying and describing one's emotions. Recent research has associated differential effects of the alexithymia facets to hypothalamic-pituitary-adrenal (HPA) axis markers during stress. This study aimed to analyze how the facets of alexithymia interact with autonomic reactivity as well as self- and observer-rated anxiety during a social stress task.

METHODS

With the use of a public-speaking paradigm, skin conductance levels (SCLs) and heart rate (HR) during the defined periods of baseline, preparation, stress, and recovery were assessed in 60 volunteers (42 females, mean age 22.8) categorized as having either high (HDA) or low (LDA) degrees of alexithymia.

RESULTS

We found smaller SCLs during preparation and speech in the HDA group. Regression analyses indicated that only the alexithymia facet "difficulty in describing feelings" (DDF) was associated with smaller electrodermal responses. In the HDA group, self- and observer-rated anxiety was higher in the HDA than in the LDA group, which was attributable to higher scores in the subscales "difficulty in identifying feelings" (DIF) and "externally oriented thinking" (EOT).

CONCLUSIONS

Our data support and specify the decoupling hypothesis of alexithymia by showing that the facets of alexithymia are differentially related to autonomic reactivity as well as self- and observer-rated anxiety during social stress.

OBJECTIVE

The Patient-Reported Outcomes (PRO) Measurement Information System (PROMIS(®)) has developed assessment tools for numerous PROs, most using a 7-day recall format. We examined whether modifying the recall period for use in daily diary research would affect the psychometric characteristics of several PROMIS measures.

METHODS

Daily versions of short-forms for three PROMIS domains (pain interference, fatigue, depression) were administered to a general population sample (n = 100) for 28 days. Analyses used multilevel item response theory (IRT) models. We examined differential item functioning (DIF) across recall periods by comparing the IRT parameters from the daily data with the PROMIS 7-day recall IRT parameters. Additionally, we examined whether the IRT parameters for day-to-day within-person changes are invariant to those for between-person (cross-sectional) differences in PROs.

RESULTS

Dimensionality analyses of the daily data suggested a single dimension for each PRO domain, consistent with PROMIS instruments. One-third of the daily items showed uniform DIF when compared with PROMIS 7-day recall, but the impact of DIF on the scale level was minor. IRT parameters for within-person changes differed from between-person parameters for 3 depression items, which were more sensitive for measuring change than between-person differences, but not for pain interference and fatigue items. Notably, mean scores from daily diaries were significantly lower than the PROMIS 7-day recall norms.

CONCLUSIONS

The results provide initial evidence supporting the adaptation of PROMIS measures for daily diary research. However, scores from daily diaries cannot be directly interpreted on PROMIS norms established for 7-day recall.

Objective: While it is well known that mental health problems are common consequences of deadly pandemics, the association with alexithymia is less clear. This study examined this association in an evaluation of home-quarantined university students during the 2019/2020 COVID-19 pandemic in China.

Methods: In total, 2501 home-quarantined students from six southwest Chinese universities completed the following questionnaires: the 20-item Toronto Alexithymia Scale (TAS-20), the Posttraumatic Stress Disorder Checklist-Civilian Version (PCL-C), and the Patients Health Questionnaire-9 (PHQ-9), after which structural equation modeling (SEM) and mediation analyses were employed to extract and evaluate the possible associations.

Results: It was found that participants with probable depression or PTSD also reported more severe alexithymia features, such as difficulties in identifying feelings (DIF) or describing feelings (DDF). Alexithymia was also found to partially mediate the effect of number of exposures on mental health problems.

Conclusion: These results suggested that implementing strategies to assist young people identify and deal with their own emotions and those of others could prevent or mitigate the mental health problems associated with deadly pandemic events. However, future longitudinal studies are needed to examine the specific involvement of DIF or DDF in people with mental health problems.

Keywords: Alexithymia; COVID-19; Depression; PTSD; Undergraduate.

OBJECTIVE

To evaluate the construct validity of the Copenhagen Psychosocial Questionnaire II (COPSOQ II) by means of tests for differential item functioning (DIF) and differential item effect (DIE).

METHODS

We used a Danish general population postal survey (n = 4,732 with 3,517 wage earners) with a one-year register based follow up for long-term sickness absence. DIF was evaluated against age, gender, education, social class, public/private sector employment, and job type using ordinal logistic regression. DIE was evaluated against job satisfaction and self-rated health (using ordinal logistic regression), against depressive symptoms, burnout, and stress (using multiple linear regression), and against long-term sick leave (using a proportional hazards model). We used a cross-validation approach to counter the risk of significant results due to multiple testing.

RESULTS

Out of 1,052 tests, we found 599 significant instances of DIF/DIE, 69 of which showed both practical and statistical significance across two independent samples. Most DIF occurred for job type (in 20 cases), while we found little DIF for age, gender, education, social class and sector. DIE seemed to pertain to particular items, which showed DIE in the same direction for several outcome variables.

CONCLUSIONS

The results allowed a preliminary identification of items that have a positive impact on construct validity and items that have negative impact on construct validity. These results can be used to develop better shortform measures and to improve the conceptual framework, items and scales of the COPSOQ II.

CONCLUSIONS

We conclude that tests of DIF and DIE are useful for evaluating construct validity.

Aim: The threats of novel coronavirus disease 2019 (COVID-19) have caused fears worldwide. The Fear of COVID-19 Scale (FCV-19S) was recently developed to assess the fear of COVID-19. Although many studies found that the FCV-19S is psychometrically sound, it is unclear whether the FCV-19S is invariant across countries. The present study aimed to examine the measurement invariance of the FCV-19S across eleven countries.

Design: Cross-sectional study.

Methods: Using data collected from prior research on Bangladesh (N = 8,550), United Kingdom (N = 344), Brazil (N = 1,843), Taiwan (N = 539), Italy (N = 249), New Zealand (N = 317), Iran (N = 717), Cuba (N = 772), Pakistan (N = 937), Japan (N = 1,079) and France (N = 316), comprising a total 15,663 participants, the present study used the multigroup confirmatory factor analysis (CFA) and Rasch differential item functioning (DIF) to examine the measurement invariance of the FCV-19S across country, gender and age (children aged below 18 years, young to middle-aged adults aged between 18 and 60 years, and older people aged above 60 years).

Results: The unidimensional structure of the FCV-19S was confirmed. Multigroup CFA showed that FCV-19S was partially invariant across country and fully invariant across gender and age. DIF findings were consistent with the findings from multigroup CFA. Many DIF items were displayed for country, few DIF items were displayed for age, and no DIF items were displayed for gender.

Conclusion: Based on the results of the present study, the FCV-19S is a good psychometric instrument to assess fear of COVID-19 during the pandemic period. Moreover, the use of FCV-19S is supported in at least ten countries with satisfactory psychometric properties.

Keywords: COVID-19; FCV-19S; Fear of COVID-19; Rasch analysis; assessment; cross-cultural; differential item functioning.

OBJECTIVE

Thyroid diseases are common and often affect quality of life (QoL). No cross-culturally validated patient-reported outcome measuring thyroid-related QoL is available. The purpose of the present study was to test the cross-cultural validity of the newly developed thyroid-related patient-reported outcome ThyPRO, using tests for differential item functioning (DIF) according to language version.

METHODS

The ThyPRO consists of 85 items summarized in 13 multi-item scales and one single item. Scales cover physical and mental symptoms, well-being and function as well as social and daily function and cosmetic concerns. Translation applied standard forward-backward methodology with subsequent cognitive interviews and reviews. Responses (N = 1,810) to the ThyPRO were collected in seven countries: UK (n = 166), The Netherlands (n = 147), Serbia (n = 150), Italy (n = 110), India (n = 148), Denmark (n = 902) and Sweden (n = 187). Translated versions were compared pairwise to the English version by examining uniform and nonuniform DIF, i.e., whether patients from different countries respond differently to a particular item, although they have identical level of the concept measured by the item. Analyses were controlled for thyroid diagnosis. DIF was investigated by ordinal logistic regression, testing for both statistical significance and magnitude (ΔR (2)>> 0.02). Scale level was estimated by the sum score, after purification.

RESULTS

For twelve of the 84 tested items, DIF was identified in more than one language. Eight of these were small, but four were indicative of possible low translatability. Twenty-one instances of DIF in single languages were identified, indicating potential problems with the particular translation. However, only seven were of a magnitude which could affect scale scores, most of which could be explained by sample differences not controlled for.

CONCLUSIONS

The ThyPRO has good cross-cultural validity with only minor cross-cultural invariance and is recommended for use in international multicenter studies.

BACKGROUND

Differentiation-inducing factor 1 [DIF-1; 1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl) hexan-1-one] from Dictyostelium discoideum exhibits antiproliferative activity in mammalian cells. We have previously shown that phosphodiesterase 1 (PDE1) is a pharmacological target of DIF-1, but there are no reports of PDE1 in human malignant melanoma cells. Therefore, we characterized PDE1 in human malignant melanoma MAA cells.

METHODS

PDE1 mRNA expression was investigated in MAA cells. The full open reading frames for human PDE1C1 and PDE1C3 were cloned. Cell growth was determined by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] assay.

RESULTS

PDE1C mRNA expression was detected in MAA cells. The nucleotide sequence of PDE1C1 was identical to that of human PDE1C1, previously published. At nucleotide 2246 in PDE1C3, A was replaced by G, but this did not change the encoded amino acid. Cell growth was inhibited by the PDE1 inhibitor vinpocetin.

CONCLUSIONS

PDE1C mRNA is expressed and may play an important role in human malignant melanoma MAA cells.

OBJECTIVE

Item response bias (also called differential item functioning, DIF) in Instrumental Activities of Daily Living (IADL) occurs when members of different groups possessing the same disability level do not have the same probability of responding positively for a given item(s). This study aimed to identify the extent of DIF by gender, age, ethnicity, and dementia groups in IADL estimates in Asian (Chinese, Malays, and Indian) elderly subjects.

METHODS

Data of 1,072 noninstitutionalized elderly subjects were analyzed using Multiple-Indicator Multiple-Cause (MIMIC) latent variable modeling.

RESULTS

Given the same functional level, older elderly were less likely to report needing help with preparing meals; men were more likely to report needing help with preparing meals, doing laundry, and taking medication; Malays and demented elderly were more likely to report needing help with using the telephone. The impact of DIF on group differences in cognitive IADL was highest for ethnicity (58%), followed by gender (50%), and dementia (23%); whereas 92% and 5% of group differences in physical IADL were for gender and age, respectively.

CONCLUSIONS

Item-response bias in IADL scale by gender, age, ethnicity, and dementia should be considered in direct comparisons of disability status among population groups.

BACKGROUND

The Educational Needs Assessment Tool (the ENAT) is a 39-item patient questionnaire originally developed in the UK to assess educational needs of patients with rheumatoid arthritis (RA). The objective of this study was to assess the cross-cultural validity of the ENAT in 7 European countries.

METHODS

The ENAT was translated into Dutch, Finnish, Norwegian, Portuguese, Spanish and Swedish versions by using Beaton's cross-cultural adaptation process, and was completed by a convenience sample of patients with RA in each country. The generated country-specific data were assessed for construct validity and were then pooled and assessed for cross-cultural invariance using Rasch analysis.

RESULTS

Individual country-specific analysis showed adequate fit to the Rasch model after adjustment for local dependency within domains. When data from the different countries were pooled, the 39 items deviated significantly from Rasch model's expectations (X(2)=977.055, DF=351, p=0.000, PSI=0.976). Again, most items within domains were found to be locally dependent, significantly affecting the fit. Consequently each domain was treated as a unit (i.e. testlet) and the ENAT was re-analysed as a seven-testlet scale resulting into a good fit to the Rasch model (X(2)=71.909; DF=63; p=0.207, PSI=0.951). A test of strict unidimensionality confirmed that all domains contributed to measuring a single construct. Cross-cultural non-invariance was discounted by splitting domains for DIF maintaining an excellent fit to the Rasch model. This allowed calibration of the ENAT into an interval scale.

CONCLUSIONS

The ENAT is a simple tool, which is a valid measure of educational needs of people with RA. Adjustment for cross-cultural non-invariance is available if data from the 7 European countries are to be pooled or compared.

The dif locus is a RecA-independent recombination site, located in the terminus region of the chromosome of Escherichia coli. This site functions to reduce circular dimer chromosomes to monomers before cell division. Strains lacking this site exhibit the Dif phenotype, in which a fraction of the cells form extended filaments with abnormal nucleoids, and the SOS system is induced. We have used a transposon (Tndif), as well as linear transformation, to position dif in 19 locations around the chromosome. All of the suppressing insertions that we obtained were within 10 kb of the normal site, even in strains in which the normal symmetry, between the origin of replication and dif had been altered by 200 kb. We also observed that the nonsuppressing insertions in the terminus region became suppressing if a deletion occurred that extended from the ectopic site up to or past the normal location of dif. We propose that dif is normally located at the center of converging polarities in the terminus region and that deletions that restore suppression do so by placing ectopic sites once again at the center of this polarity. Similar results and conclusions are described in this issue.

OBJECTIVE

To validate the educational needs assessment tool (ENAT) as a generic tool for assessing the educational needs of patients with rheumatic diseases in European Countries.

METHODS

A convenience sample of patients from seven European countries was included comprising the following diagnostic groups: ankylosing spondylitis, psoriatic arthritis, systemic sclerosis, systemic lupus erythematosus, osteoarthritis (OA) and fibromyalgia syndrome. Translated versions of the ENAT were completed through surveys in each country. Rasch analysis was used to assess the construct validity of the adapted ENATs including differential item functioning by culture (cross-cultural DIF). Initially, the data from each country and diagnostic group were fitted to the Rasch model separately, and then the pooled data from each diagnostic group.

RESULTS

The sample comprised 3015 patients; the majority, 1996 (66.2%), were women. Patient characteristics (stratified by diagnostic group) were comparable across countries except the educational background, which was variable. In most occasions, the 39-item ENAT deviated significantly from the Rasch model expectations (item-trait interaction χ(2) p<0.05). After correction for local dependency (grouping the items into seven domains and analysing them as 'testlets'), fit to the model was satisfied (item-trait interaction χ(2) p>0.18) in all pooled disease group datasets except OA (χ(2)=99.91; p=0.002). The internal consistency in each group was high (Person Separation Index above 0.90). There was no significant DIF by person characteristics. Cross-cultural DIF was found in some items, which required adjustments. Subsequently, interval-level scales were calibrated to enable transformation of ENAT scores when required.

CONCLUSIONS

The adapted ENAT is a valid tool with high internal consistency providing accurate estimation of the educational needs of people with rheumatic diseases. Cross-cultural comparison of educational needs is now possible.

The cer-Xer dimer resolution system of plasmid ColE1 is highly selective, acting only at sites on the same molecule and in direct repeat. Recombination requires the XerCD recombinase and accessory proteins ArgR and PepA. The Escherichia coli chromosome dimer resolution site dif and the type II hybrid site use the same recombinase but are independent of ArgR and PepA and show no site selectivity. This has led to the proposal that ArgR and PepA are responsible for the imposition of constraint. We describe here the characterization of a novel class of "conditionally constrained' multimer resolution sites whose properties support this hypothesis. In the presence of ArgR and PepA, plasmids containing conditionally constrained sites are monomeric, but in their absence, extensive multimerisation is seen. A mutant ArgR derivative (ArgR110), which is defective in cer-mediated dimer resolution, remains able to prevent plasmid multimerisation by a conditionally constrained site. This implies that the accessory factors block recombination in trans rather than ensuring rapid multimer resolution. When the distance between the ArgR and XerCD binding sites in a conditionally constrained site was altered by a non-integral number of helical turns, the site became unconstrained. Constraint was restored by the insertion of a full helical turn.