OBJECTIVE

This study aims to validate a self-administered, multidimensional QoL instrument based on the point of view of caregivers of individuals with schizophrenia.

METHODS

Data were collected through the departments of six psychiatric hospitals in France (n=246). The item reduction and validation processes were based on both item response theory and classical test theory.

RESULTS

The S-CGQoL contains 25 items describing seven dimensions (Psychological and Physical Well-Being; Psychological Burden and Daily Life; Relationships with Spouse; Relationships with Psychiatric Team; Relationships with Family; Relationships with Friends; and Material Burden). The seven-factor structure accounted for 74.4% of the total variance. Internal consistency was satisfactory; Cronbach's alpha coefficients ranged from 0.79 to 0.92 in the whole sample. The scalability was satisfactory, with INFIT statistics falling within an acceptable range. In addition, the results confirmed the absence of DIF and supported the invariance of the item calibrations.

CONCLUSIONS

The S-CGQoL is a self-administered QoL instrument that presents satisfactory psychometric properties and can be completed in 5 min, thereby fulfilling the goal of brevity sought in research and clinical practice.

Bone scaffolds for regenerative medicine applications should have the ability to promote adhesion, proliferation and differentiation of osteoblast cells. Osteoconductive, osteoinductive and osteopromotive properties of the material are essential for rapid bone regeneration and new bone formation. In this study, the osteogenic potential of two novel tri-component scaffolds composed of krill chitosan, bacterial β-1,3-glucan and bioceramics (HAp or a mix of HAp/β-TCP granules) was investigated. The typical markers of the first (type I collagen), second (bone alkaline phosphatase) and third stages (osteocalcin) of the osteoblast differentiation process were evaluated during in vitro experimentation. The study was carried out using three various osteoblastic cell lines (normal human fetal osteoblast cells hFOB 1.19, human osteoblast-like cells derived from osteosarcoma Saos-2 and mouse calvarial preosteoblast cells MC3T3-E1 Subclone 4). The bone alkaline phosphatase (bALP) and osteocalcin (OC) were determined quantitatively using enzyme-linked immunosorbent assays, and type I collagen (Col I) was evaluated qualitatively using the direct immunofluorescence (DIF) method. The data obtained clearly prove that novel scaffolds have the ability to increase bALP activity, to enhance extracellular matrix synthesis (Col I and OC) and to induce mineralized nodule formation during osteogenic differentiation. In conclusion, novel tri-component materials have osteoconductive and osteopromotive properties, and thus are promising materials in bone tissue engineering applications to accelerate the bone regeneration process.

Dictyostelium amoebae accomplish a starvation-induced developmental process by aggregating into a mound and forming a single fruiting body with terminally differentiated spores and stalk cells. culB was identified as the gene disrupted in a developmental mutant with an aberrant prestalk cell differentiation phenotype. The culB gene product appears to be a homolog of the cullin family of proteins that are known to be involved in ubiquitin-mediated protein degradation. The culB mutants form supernumerary prestalk tips atop each developing mound that result in the formation of multiple small fruiting bodies. The prestalk-specific gene ecmA is expressed precociously in culB mutants, suggesting that prestalk cell differentiation occurs earlier than normal. In addition, when culB mutant cells are mixed with wild-type cells, they display a cell-autonomous propensity to form stalk cells. Thus, CulB appears to ensure that the proper number of prestalk cells differentiate at the appropriate time in development. Activation of cyclic AMP-dependent protein kinase (PKA) by disruption of the regulatory subunit gene (pkaR) or by overexpression of the catalytic subunit gene (pkaC) enhances the prestalk/stalk cell differentiation phenotype of the culB mutant. For example, culB- pkaR- cells form stalk cells without obvious multicellular morphogenesis and are more sensitive to the prestalk O (pstO) cell inducer DIF-1. The sensitized condition of PKA activation reveals that CulB may govern prestalk cell differentiation in Dictyostelium, in part by controlling the sensitivity of cells to DIF-1, possibly by regulating the levels of one or more proteins that are rate limiting for prestalk differentiation.

OBJECTIVE

This study investigated the internal construct validity and dimensionality of the Melbourne Assessment of Unilateral Upper Limb Function (Melbourne Assessment), a widely-used measure of quality of upper limb movement, valid for children aged 2 years 6 months to 15 years with cerebral palsy.

METHODS

Rasch analysis was used to assess of Melbourne Assessment raw scores for 163 children (94 males, 69 females; mean age 8y, SD 3y 5mo). Analysis was undertaken on the full scale comprising 37 scores and on groups of scores separated into four distinct movement subscales: range of movement, accuracy, dexterity, and fluency. Tests were conducted to evaluate overall model fit, item fit, suitability of the response options, unidimensionality, and differential item functioning (DIF) for sex, child age, and different raters.

RESULTS

The results did not support the unidimensionality of the 37-score scale. The four subscales showed adequate model fit after removal of some score items, and rescaling of others. The resulting subscales showed good internal consistency and no DIF for sex or child age.

CONCLUSIONS

This study provides empirical support for a revised version of the Melbourne Assessment which comprises 14 tasks and 30 movement scores grouped across four separate subscales. Further testing is required to assess the responsiveness of subscales to clinically important change.

Background and aims The Bergen Social Media Addiction Scale (BSMAS), a six-item self-report scale that is a brief and effective psychometric instrument for assessing at-risk social media addiction on the Internet. However, its psychometric properties in Persian have never been examined and no studies have applied Rasch analysis for the psychometric testing. This study aimed to verify the construct validity of the Persian BSMAS using confirmatory factor analysis (CFA) and Rasch models among 2,676 Iranian adolescents. Methods In addition to construct validity, measurement invariance in CFA and differential item functioning (DIF) in Rasch analysis across gender were tested for in the Persian BSMAS. Results Both CFA [comparative fit index (CFI) = 0.993; Tucker-Lewis index (TLI) = 0.989; root mean square error of approximation (RMSEA) = 0.057; standardized root mean square residual (SRMR) = 0.039] and Rasch (infit MnSq = 0.88-1.28; outfit MnSq = 0.86-1.22) confirmed the unidimensionality of the BSMAS. Moreover, measurement invariance was supported in multigroup CFA including metric invariance (ΔCFI = -0.001; ΔSRMR = 0.003; ΔRMSEA = -0.005) and scalar invariance (ΔCFI = -0.002; ΔSRMR = 0.005; ΔRMSEA = 0.001) across gender. No item displayed DIF (DIF contrast = -0.48 to 0.24) in Rasch across gender. Conclusions Given the Persian BSMAS was unidimensional, it is concluded that the instrument can be used to assess how an adolescent is addicted to social media on the Internet. Moreover, users of the instrument may comfortably compare the sum scores of the BSMAS across gender.

BACKGROUND

Rasch analysis with a focus on Differential Item Functioning (DIF) is increasingly used for examination of psychometric properties of health outcome measures. To take account of DIF in order to retain precision of measurement, split of DIF-items into separate sample specific items has become a frequently used technique. The purpose of the paper is to present and summarise recent advances of analysis of DIF in a unified methodology. In particular, the paper focuses on the use of analysis of variance (ANOVA) as a method to simultaneously detect uniform and non-uniform DIF, the need to distinguish between real and artificial DIF and the trade-off between reliability and validity. An illustrative example from health research is used to demonstrate how DIF, in this case between genders, can be identified, quantified and under specific circumstances accounted for using the Rasch model.

METHODS

Rasch analyses of DIF were conducted of a composite measure of psychosomatic problems using Swedish data from the Health Behaviour in School-aged Children study for grade 9 students collected during the 1985-2014 time periods.

RESULTS

The procedures demonstrate how DIF can be identified efficiently by ANOVA of residuals, and how the magnitude of DIF can be quantified and potentially accounted for by resolving items according to identifiable groups and using principles of test equating on the resolved items. The results of the analysis also show that the real DIF in some items does affect person measurement estimates.

CONCLUSIONS

Firstly, in order to distinguish between real and artificial DIF, the items showing DIF initially should not be resolved simultaneously but sequentially. Secondly, while resolving instead of deleting a DIF item may retain reliability, both options may affect the content validity negatively. Resolving items with DIF is not justified if the source of the DIF is relevant for the content of the variable; then resolving DIF may deteriorate the validity of the instrument. Generally, decisions on resolving items to deal with DIF should also rely on external information.

BACKGROUND

Two typical pathological changes can develop in the type 2 diabetic nephropathy: one is diffuse glomerulosclerosis (DIF) and the other is nodular glomerular lesion (NOD). The aim of this study is to retrospectively investigate these two types of diabetic nephropathy and compare the characteristics of clinical findings and prognosis.

METHODS

One hundred and twenty-four patients with biopsy-proven diabetic nephropathy, including 58 DIF and 66 NOD were investigated in this study. Clinical data were registered for each patient: age, sex, diabetes duration, hypertension duration, body mass index (BMI), and laboratory tests included: glycosylated hemoglobin, plasma albumin, plasma cholesterol and triglycerides, serum creatinine, proteinuria, urine osmole, urine N-acetyl-beta-D-glucosaminidase (NAG) enzyme and creatinine clearance rate (Ccr). Furthermore, the 1- and 5-year renal survival rates were analysed and compared.

RESULTS

(1) Compared with DIF patients, NOD patients had a longer duration of diabetic mellitus, and higher levels of proteinuria and NAG enzyme, along with lower BMI, Ccr and plasma albumin levels (p<0.01). (2) In the NOD cases, there were 90% presented diabetic retinopathy; while in the DIF cases, there were 14% presented diabetic retinopathy. (3) In the DIF patients, the 1- and 5-year renal survival rates were 96 and 78%, respectively, while in the NOD patients, the rates were 86 and 18%, respectively (p<0.01).

CONCLUSIONS

The NOD patients had longer diabetic durations, more severe renal damage, and exhibit a poorer renal prognosis. Furthermore, the NOD patients revealed more frequently evidence of diabetic retinopathy.

BACKGROUND

The multiple mini-interview (MMI) was initially designed to test non-cognitive characteristics related to professionalism in entry-level students. However, it may be testing cognitive reasoning skills. Candidates to medical and dental schools come from diverse backgrounds and it is important for the validity and fairness of the MMI that these background factors do not impact on their scores.

METHODS

A suite of advanced psychometric techniques drawn from item response theory (IRT) was used to validate an MMI question bank in order to establish the conceptual equivalence of the questions. Bias against candidate subgroups of equal ability was investigated using differential item functioning (DIF) analysis.

RESULTS

All 39 questions had a good fit to the IRT model. Of the 195 checklist items, none were found to have significant DIF after visual inspection of expected score curves, consideration of the number of applicants per category, and evaluation of the magnitude of the DIF parameter estimates.

CONCLUSIONS

The question bank contains items that have been studied carefully in terms of model fit and DIF. Questions appear to measure a cognitive unidimensional construct, 'entry-level reasoning skills in professionalism', as suggested by goodness-of-fit statistics. The lack of items exhibiting DIF is encouraging in a contemporary high-stakes admission setting where candidates of diverse personal, cultural and academic backgrounds are assessed by common means. This IRT approach has potential to provide assessment designers with a quality control procedure that extends to the level of checklist items.

Measurement invariance is a prerequisite for confident cross-cultural comparisons of personality profiles. Multigroup confirmatory factor analysis was used to detect differential item functioning (DIF) in factor loadings and intercepts for the Revised NEO Personality Inventory (P. T. Costa, Jr., & R. R. McCrae, 1992) in comparisons of college students in the United States (N = 261), Philippines (N = 268), and Mexico (N = 775). About 40%-50% of the items exhibited some form of DIF and item-level noninvariance often carried forward to the facet level at which scores are compared. After excluding DIF items, some facet scales were too short or unreliable for cross-cultural comparisons, and for some other facets, cultural mean differences were reduced or eliminated. The results indicate that considerable caution is warranted in cross-cultural comparisons of personality profiles.

OBJECTIVE

To evaluate whether morphologic differences in idiopathic epiretinal membranes seen on optical coherence tomography may help predict surgical outcomes.

METHODS

Seventy-five eyes of 74 patients who underwent primary pars plana vitrectomy with membrane peeling were retrospectively reviewed. Outcome measures included visual acuity, macular contour on optical coherence tomography, central macular thickness, and reoperation rate.

RESULTS

According to the preoperative macular contour, 75 eyes were categorized into 4 types: 42 eyes were included in the diffuse (DIF) type, 12 in the cystoid macular edema (CME) type, 14 in the pseudolamellar hole (PLH) type, and 7 in the vitreomacular traction (VMT) type. Surgical procedure significantly improved vision in all types except for the PLH type (DIF, P < 0.0001; CME, P = 0.0378; PLH, P = 0.838; and VMT, P = 0.0273). There was a significant relationship between pre- and postoperative macular contour. All preoperative VMT showed normal contour on postoperative optical coherence tomography but had the highest reoperation rate.

CONCLUSIONS

Surgical intervention for the PLH-type epiretinal membrane was not associated with the visual improvement seen in other epiretinal membrane types, and the VMT type had the highest reoperation rate. Future studies should evaluate the potential benefit of internal limiting membrane peeling with or without short-term gas tamponade in these cases.

The DIFs are unusual, chlorinated molecules which induce stalk cell differentiation during the later, multicellular phase of Dictyostelium development. Here we provide evidence that one or more DIFs have a role during early development, when small amounts are known to be made. Initial indications came from an optical technique which detects changes in shape or cohesion of cells in suspension (Gerisch and Hess, PNAS 71, 2118, 1974). After a period of optical inactivity at the start of development, cell suspensions normally produce spontaneous spike-shaped light-scattering oscillations synchronised by oscillations in extracellular cAMP levels, followed by sinusoidal oscillations where the synchroniser is not known. DIFs 1 and 2 produce optical responses from cells at all these early stages of development. The phase of both spiked and sinusoidal oscillations can be shifted, indicating an effect on the oscillator in each case. We find further: (1) cAMP oscillations and cAMP relay during spiked oscillations are transiently inhibited by DIF-1. (2) DIF-1 causes a transient decrease in cellular cGMP levels in cells taken before oscillations commence and likewise inhibits the cGMP response to a cAMP stimulus in cells taken later in development. Cytoskeletal organization and hence cell shape might be affected by DIF-1 by this indirect route. (3) The effects of DIF-1 are transient, even though it is essentially stable in the cell suspension. Cells somehow adapt to DIF-1. (4) The effects are chemically specific: DIF-1 and DIF-2 are active at 10(-7) to 10(-8) M, with DIF-2 being the more active, whereas related compounds have little or no activity at 10(-6) M. These results indicate that cells are responsive to DIFs 1 and 2 from the start of development and suggest a wider role for the DIFs. This role might involve effects on cAMP signalling and on intracellular second messengers.

Differentiation-inducing factor 1 [DIF-1; 1-(3,5-dichloro-2,6-dihydroxy-4-methoxyphenyl)-hexan-1-one] induces stalk cell differentiation during Dictyostelium development. It is present as a gradient in the multicellular slug, its lowest concentration being in the anterior. Here we demonstrate the existence of a localized sink for DIF-1, also in the anterior of the slug, which could be responsible for generating the DIF-1 gradient. DIF-1 is metabolized extensively by developing cells, initially by a mono-dechlorination. We used an enzyme assay for DIF-1 dechlorinase to examine its distribution in the slug. DIF-1 dechlorinase activity is 30-fold higher in prestalk cells (largely anterior) compared with prespore cells (posterior) when these are separated from each other on Percoll density gradients. Dissection experiments showed that DIF-1 dechlorinase is 25-fold enriched in the anterior 13% of the slug compared with the rest. These experiments also showed that DIF-1 dechlorinase is more anterior-enriched than the standard prestalk markers, the ecmA and ecmB mRNAs. When cut from a slug, both prestalk and prespore fragments regulate to restore the missing cell type. Prespore fragments rapidly regain (by 30 min) a DIF-1 sink in their anteriors, and prestalk fragments restore a posterior zone with low DIF-1 dechlorinase by 4 hr after cutting. The reappearance of the DIF-1 sink in the anterior of prespore fragments is accomplished without detectable cell sorting and may, therefore, be in response to positional signals. Finally, a localized sink may provide a general way of producing a gradient of a signal substance in a developing embryo.

OBJECTIVE

The liver is perfused through the portal vein and the hepatic artery. When its perfusion is assessed using positron emission tomography (PET) and (15)O-labeled water (H(2) (15)O), calculations require a dual blood input function (DIF), i.e., arterial and portal blood activity curves. The former can be generally obtained invasively, but blood withdrawal from the portal vein is not feasible in humans. The aim of the present study was to develop a new technique to estimate quantitative liver perfusion from H(2) (15)O PET images with a completely non-invasive approach.

METHODS

We studied normal pigs (n=14) in which arterial and portal blood tracer concentrations and Doppler ultrasonography flow rates were determined invasively to serve as reference measurements. Our technique consisted of using model DIF to create tissue model function and the latter method to simultaneously fit multiple liver time-activity curves from images. The parameters obtained reproduced the DIF. Simulation studies were performed to examine the magnitude of potential biases in the flow values and to optimize the extraction of multiple tissue curves from the image.

RESULTS

The simulation showed that the error associated with assumed parameters was <10%, and the optimal number of tissue curves was between 10 and 20. The estimated DIFs were well reproduced against the measured ones. In addition, the calculated liver perfusion values were not different between the methods and showed a tight correlation (r=0.90).

CONCLUSIONS

In conclusion, our results demonstrate that DIF can be estimated directly from tissue curves obtained through H(2) (15)O PET imaging. This suggests the possibility to enable completely non-invasive technique to assess liver perfusion in patho-physiological studies.

Myxococcus xanthus, a Gram-negative soil bacterium, undergoes multicellular development when nutrients become limiting. Aggregation, which is part of the developmental process, requires the surface motility of this organism. One component of M. xanthus motility, the social (S) gliding motility, enables the movement of cells in close physical proximity. Previous studies demonstrated that the cell surface-associated exopolysaccharide (EPS) is essential for S motility and that the Dif proteins form a chemotaxis-like pathway that regulates EPS production in M. xanthus. DifA, a homologue of methyl-accepting chemotaxis proteins (MCPs) in the Dif system, is required for EPS production, S motility and development. In this study, a spontaneous extragenic suppressor of a difA deletion was isolated in order to identify additional regulators of EPS production. The suppressor mutation was found to be a single base pair insertion in cheW7 at the che7 chemotaxis gene cluster. Further examination indicated that mutations in cheW7 may lead to the interaction of Mcp7 with DifC (CheW-like) and DifE (CheA-like) to reconstruct a functional pathway to regulate EPS production in the absence of DifA. In addition, the cheW7 mutation was found to partially suppress a pilA mutation in EPS production in a difA(+) background. Further deletion of difA from the pilA cheW7 double mutant resulted in a triple mutant that produced wild-type levels of EPS, implying that DifA (MCP-like) and Mcp7 compete for interactions with DifC and DifE in the modulation of EPS production.

BACKGROUND

The demonstration of tissue-bound immunoreactants by direct immunofluorescence microscopy (DIF) is a valuable parameter in the diagnosis of various autoimmune and immunecomplex-mediated skin diseases. For preservation of tissue-bound immunoreactants, biopsies are usually fresh-frozen in liquid nitrogen or transported in Michel's fixative. But even optimally preserved tissue specimens are no guarantee for the correct diagnosis by DIF, especially when weak to moderate IgG fluorescence of the epidermal basement membrane zone is involved. In such cases false negative results are easily obtained due to the relatively high dermal "background" fluorescence produced by polyclonal anti-human IgG fluorescein conjugates.

METHODS

In the present study we have compared the use of normal saline (0.9% NaCl) with liquid nitrogen and Michel's fixative as transport medium for skin biopsies. From 25 patients with an autoimmune skin disease (pemphigus, pemphigoid, lupus erythematosus and vasculitis) four matched skin biopsies were obtained and transported in either saline for 24 and 48 hours, liquid nitrogen, or Michel's fixative for 48 hours.

RESULTS

Direct IF microscopy showed significant reduction of background fluorescence (p < 0.01) and relatively enhanced desired specific (IgG, IgA) staining in biopsies transported in saline. A conclusive or tentative IF diagnosis was reached in 92% after 24 h saline, 83% after 48 h saline, 68% after freezing in liquid nitrogen, and 62% after 48 h Michel's medium (n = 25).

CONCLUSIONS

We conclude that transporting biopsies without freezing in normal saline for 24 hours is an adequate and attractive method for routine IF diagnosis in autoimmune and immune complex-mediated dermatoses. The superior results with saline incubation are explained by washing away of IgG background in dermis and epidermis.

The E. coli chromosome replication arms are polarized by motifs such as RRNAGGGS oligomers, found preferentially on leading strands. Their skew increases regularly from the origin to dif (the site in the center of the terminus where chromosome dimer resolution occurs), to reach a value of 90% near dif. Convergent information indicates that polarization in opposite directions from the dif region controls tightly the activity of dif, probably by orienting mobilization of the terminus at cell division. Another example of polarization is the presence, in the region peripheral to the terminus, of small non-divisible zones whose inversion interferes with spatial separation of sister nucleoids. The two phenomena may contribute to the organization of the Ter macrodomain.

Object naming tests are commonly included in neuropsychological test batteries. Differential item functioning (DIF) in these tests due to cultural and language differences may compromise the validity of cognitive measures in diverse populations. We evaluated 26 object naming items for DIF due to Spanish and English language translations among Latinos (n=1,159), mean age of 70.5 years old (Standard Deviation (SD)±7.2), using the following four item response theory-based approaches: Mplus/Multiple Indicator, Multiple Causes (Mplus/MIMIC; Muthén & Muthén, 1998-2011), Item Response Theory Likelihood Ratio Differential Item Functioning (IRTLRDIF/MULTILOG; Thissen, 1991, 2001), difwithpar/Parscale (Crane, Gibbons, Jolley, & van Belle, 2006; Muraki & Bock, 2003), and Differential Functioning of Items and Tests/MULTILOG (DFIT/MULTILOG; Flowers, Oshima, & Raju, 1999; Thissen, 1991). Overall, there was moderate to near perfect agreement across methods. Fourteen items were found to exhibit DIF and 5 items observed consistently across all methods, which were more likely to be answered correctly by individuals tested in Spanish after controlling for overall ability.

BACKGROUND

Despite recent advances, work disability in rheumatoid arthritis (RA) remains common. Work disability is frequently preceded by a period of work instability characterised by a mismatch between an individual's functional abilities and job demands. This could raise the risk of work disability if not resolved. A work instability scale for RA (RA-WIS) has previously been developed to screen for this risk. The objective of this study was the adaptation of this scale into French, Dutch and German.

METHODS

Different language versions of the RA-WIS were produced through a process of forward and back translations. The new scales were tested for face validity. English data from the original developmental study was pooled with data generated through postal surveys in each country. The internal construct and cross-cultural validity of the new scales were assessed using Rasch analysis, including differential item functioning (DIF) by culture.

RESULTS

The pooled data showed good fit to the Rasch model and demonstrated strict unidimensionality. DIF was found to be present for six items, but these appeared both to cancel out at the test level and have only a marginal effect on the test score itself.

CONCLUSIONS

The RA-WIS was shown to be robust to adaptation into different languages. Data fitted Rasch model expectations and strict tests of unidimensionality. This project and the continuing work on further cross-cultural adaptations have the potential to help ensure clinicians across Europe are able to support RA patients to achieve their potential in work through early identification of those most at risk.

BACKGROUND

By direct immunofluorescence (DIF), presence of immune complexes in the skin biopsy at various locations such as the dermo-epidermal junction, dermal blood vessels, etc. help to arrive at a diagnosis.

OBJECTIVE

(1) To study the role of DIF in confirmation or exclusion of diseases involving skin vis-à-vis histopathology and clinical diagnosis, (2) to describe the annual spectrum of dermatologic conditions that present to a tertiary referral center and require DIF examination of skin biopsy for confirmation of diagnosis.

METHODS

A total of 267 biopsies received over a period of 16 months in the Department of Immunopathology were analyzed along with clinical and histopathological details and the correlation between them was studied.

RESULTS

DIF was positive in 204 skin biopsies. Of these, 127 biopsies showed good clinico-immuno-histopathological correlation. In 10 cases, only DIF could clinch the diagnosis. In another nine cases, immune deposits were noted, which were unexpected in light of clinical and histopathological diagnosis. The most common skin involvement was seen in vasculitides. DIF was, however, non-contributory in lesions like erythema multiformè, post Kala-azar dermal leishmaniasis, sarcoidosis, lupus vulgaris, pyoderma gangrenosum and prurigo nodularis.

CONCLUSIONS

The DIF of skin in conjunction with histopathology gives the best diagnostic yield. It is invaluable in confirming the diagnosis of small vessel vasculitides and bullous lesions of skin and can be used as an additional tool to pinpoint the diagnosis of systemic and localized autoimmune diseases involving the skin.

41 cases with scarring alopecia seen from 1979 to 1983 were analyzed and differentiated. After exclusion of 7 cases with lichen planopilaris, of 5 cases with discoid lupus erythematosus, of 2 cases with scleroderma, and of 1 case with folliculitis decalvans, there remained 26 cases. The clinical histological and direct immunofluorescence (DIF) findings in these patients suggest that pseudopelade of Brocq might be a distinct disease unrelated to other known types of scarring alopecia. The histopathology is characteristic, and shows the following features: little or only moderate lymphocytic infiltrate, absence of significant follicular plugging, and absence or decrease of sebaceous glands. DIF is negative, occasionally only IgM can be found at the basement membrane. The course of the disease is slowly progressive (in spite of little or no visible erythema), becoming eventually stationary after several years and resulting in a more or less severe permanent hair loss.

As research continues to document differences in the prevalence of mental health problems such as depression across racial/ethnic groups, the issue of measurement equivalence becomes increasingly important to address. The Mood and Feelings Questionnaire (MFQ) is a widely used screening tool for child and adolescent depression. This study applied a differential item functioning (DIF) framework to data from a sample of 6th and 8th grade students in the Seattle Public School District (N = 3,593) to investigate the measurement equivalence of the MFQ. Several items in the MFQ were found to have DIF, but this DIF was associated with negligible individual- or group-level impact. These results suggest that differences in MFQ scores across groups are unlikely to be caused by measurement non-equivalence.

This study examined the equivalence of the English and Spanish versions of the Medicare Consumer Assessment of Health Plans Study (CAHPS) fee-for-service (FFS) survey among 2,996 Hispanic Medicare beneficiaries. Multigroup confirmatory factor analyses indicated that with few exceptions the factor structures were very similar for the English and Spanish surveys. However, item response theory-based methods for investigating differential item functioning (DIF) revealed that several items demonstrated threshold-related DIF, suggesting that respondents in the two languages utilized the response options for the items differently. The results of this study suggest the need for future qualitative research to understand how respondents comprehend the response options in the two languages.

DIF-1 is a novel, chlorinated alkyl phenone from Dictyostelium which, at very low concentrations, induces amoebae to differentiate into stalk cells and may act as a morphogen in the formation of the prestalkprespore pattern during development. We report here the existence of a developmentally regulated metabolic pathway which inactivates DIF-1. Radioisotopically labeled DIF-1 was synthesized, incubated with developing cells, the metabolites recovered, and then analyzed by high pressure liquid chromatography and TLC. At least 12 metabolites are produced and the early steps of a complex metabolic pathway have been deduced by following the flow of counts from one metabolite to another and by determining the fate of purified metabolites when they are incubated with cells. The first metabolite, DM1, is largely cell-associated whereas the more distal ones are found mainly in the medium. Metabolism inactivates DIF-1, since DM1 retains only 7% of the specific activity of DIF-1 in the stalk cell differentiation bioassay and later metabolites possess even less activity. Metabolism is developmentally regulated, increasing toward the end of aggregation to reach maximal levels at the tipped mound stage, as endogenous DIF-1 levels are themselves rising. Cells at this stage of development possess the capacity to metabolize their endogenous DIF-1 with a half-life of a few minutes. We suggest that DIF-1 metabolism is important to prevent the DIF-1 receptor system from becoming saturated by excess ligand, thus allowing cells to respond to changes in DIF-1 production. Metabolism may also produce other effector molecules from DIF-1 or produce DIF-1 gradients in the aggregate by the localized destruction of DIF-1.