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Publication
Journal: Journals of Gerontology - Series B Psychological Sciences and Social Sciences
January/14/2016
Abstract
OBJECTIVE
Due to increasing interest in the positive experiences associated with family caregiving, potential demographic group differences were examined on the Positive Aspects of Caregiving (PAC) scale at both the item and scale levels.
METHODS
Family caregivers (N = 642) completed the PAC as part of their participation in the Resources for Enhancing Alzheimer's Caregiver Health (REACH II) clinical trial. Multiple indicators, multiple causes models were used to examine potential differential item functioning (DIF) across demographic subgroups.
RESULTS
Overall PAC scale scores indicated that both Hispanics and African Americans experienced more PAC than Whites. Two items with statistically significant (p < .004) and practically meaningful (odds ratio>> 2.0) DIF were found for African American caregivers. After controlling for the underlying unidimensional construct, African Americans reported that caregiving gave them "a more positive attitude toward life" and enabled them to "appreciate life more" than either Whites or Hispanics. No instances of meaningful DIF were found between Hispanics and Whites, women and men, or spouses and nonspouses.
CONCLUSIONS
PAC scores differ significantly by race. In addition, 2 items with meaningful race DIF identify content areas that are particularly relevant to the cultural experiences of African American caregivers.
Publication
Journal: Research in Developmental Disabilities
October/21/2014
Abstract
Scoliosis Research Society-22 (SRS-22) questionnaire was developed to evaluate health-related quality of life (HRQL) in adolescent idiopathic scoliosis (AIS) patients. Rasch analysis (RA) is a statistical procedure which turns questionnaire ordinal scores into interval measures. Measures from Rasch-compatible questionnaires can be used, similar to body temperature or blood pressure, to quantify disease severity progression and treatment efficacy. Purpose of the current work is to present Rasch analysis (RA) of the SRS-22 questionnaire and to develop an SRS-22 Rasch-approved short form. 300 SRS-22 were randomly collected from 2447 consecutive IS adolescents at their first evaluation (229 females; 13.9 ± 1.9 years; 26.9 ± 14.7 Cobb°) in a scoliosis outpatient clinic. RA showed both disordered thresholds and overall misfit of the SRS-22. Sixteen items were re-scored and two misfitting items (6 and 14) removed to obtain a Rasch-compatible questionnaire. Participants HRQL measured too high with the rearranged questionnaire, indicating a severe SRS-22 ceiling effect. RA also highlighted SRS-22 multidimensionality, with pain/function not merging with self-image/mental health items. Item 3 showed differential item functioning (DIF) for both curve and hump amplitude. A 7-item questionnaire (SRS-7) was prepared by selecting single items from the original SRS-22. SRS-7 showed fit to the model, unidimensionality and no DIF. Compared with the SRS-22, the short form scale shows better targeting of the participants' population. RA shows that SRS-22 has poor clinimetric properties; moreover, when used with AIS at first evaluation, SRS-22 is affected by a severe ceiling effect. SRS-7, an SRS-22 7-item short form questionnaire, provides an HRQL interval measure better tailored to these participants.
Publication
Journal: Biophysical Journal
September/1/2015
Abstract
We have previously introduced tethered fluorophore motion (TFM), a single-molecule fluorescence technique that monitors the effective length of a biopolymer such as DNA. TFM uses the same principles as tethered particle motion (TPM) but employs a single fluorophore in place of the bead, allowing TFM to be combined with existing fluorescence techniques on a standard fluorescence microscope. TFM has been previously been used to reveal the mechanism of two site-specific recombinase systems, Cre-loxP and XerCD-dif. In this work, we characterize TFM, focusing on the theoretical basis and potential applications of the technique. Since TFM is limited in observation time and photon count by photobleaching, we present a description of the sources of noise in TFM. Comparing this with Monte Carlo simulations and experimental data, we show that length changes of 100 bp of double-stranded DNA are readily distinguishable using TFM, making it comparable with TPM. We also show that the commonly recommended pixel size for single-molecule fluorescence approximately optimizes signal to noise for TFM experiments, thus enabling facile combination of TFM with other fluorescence techniques, such as Förster resonance energy transfer (FRET). Finally, we apply TFM to determine the polymerization rate of the Klenow fragment of DNA polymerase I, and we demonstrate its combination with FRET to observe synapsis formation by Cre using excitation by a single laser. We hope that TFM will be a useful addition to the single-molecule toolkit, providing excellent insight into protein-nucleic acid interactions.
Publication
Journal: Clinical Neuropsychologist
April/27/2014
Abstract
In the present study we analyzed the psychometric characteristics of the MoCA (Portuguese version) using the Rasch model for dichotomous items. The total sample comprised of 897 participants distributed between two main subgroups: (I) healthy group that was comprised of 650 cognitively healthy community dwellers and (II) clinical group that was comprised of 90 patients with Mild Cognitive Impairment, 90 patients with Alzheimer's disease, 33 patients with frontotemporal dementia, and 34 patients with vascular dementia recruited at a reference dementia clinic. All patients were investigated through a comprehensive neuropsychological assessment, laboratory tests essential to exclude a reversible form of dementia, imaging studies (CT or MRI and SPECT or FDG-PET), Apolipoprotein E allele genotyping and CSF biomarker (Aβ42,Tau, and P-tau) analyses. The clinical diagnosis was established through the consensus of a multidisciplinary team, based on international criteria. The results demonstrated an overall good fit of both items and the person's values, a high variability on cognitive performance level, and a good quality of the measurements. The MoCA scores also demonstrated adequate discriminant validity, with high diagnostic value. DIF analyses indicated the generalized validity of the MoCA scores. In conclusion, the results of this study show the overall psychometric adequacy of the MoCA and verify the discriminant and generalized validity of the obtained results.
Publication
Journal: BioPsychoSocial Medicine
June/16/2010
Abstract
OBJECTIVE
We examined developmental aspects of the emotional awareness of adolescents by evaluating their responses to a self-reported questionnaire based on the Toronto Alexithymia Scale-20 (TAS-20).
METHODS
The items of the TAS-20 were modified to make them more understandable by adolescents, and nine new items related to a limited capacity for imagination were added. The Japanese Linguistic Ability Test and the multi-dimensional empathy scale for adolescents were administered to examine concurrent validity. Two hundred and two normative young adolescents and thirty-two adolescent patients with psychosomatic and/or behavioral problems participated in the study. Eighty junior high school students also participated in a separate examination of test-retest reliability.
RESULTS
Thirteen items were extracted after exploratory and confirmatory factor analyses, and four core factors were identified in the resulting scale: Difficulty Identifying Feelings (DIF), Difficulty Describing Feelings (DDF), Externally-Oriented Thinking (EOT) and Constricted Imaginal Capacities (CIC). Interestingly, scores on the multi-dimensional empathy scale correlated positively with DIF and DDF, but negatively with EOT and CIC. Higher DDF scores were associated with higher Japanese linguistic abilities. DIF/DDF scores were higher for females than males, irrespective of linguistic ability. Test-retest reliability coefficients were significant. The patient group showed significantly higher DIF scores than the normative students.
CONCLUSIONS
The present findings indicated that subjective difficulties in identifying and describing feelings are associated with empathetic and linguistic abilities. The developmental aspect to emotional awareness herein described suggests that self-reported questionnaires for alexithymia must be carefully constructed and examined, even for adults.
Publication
Journal: Japanese Journal of Clinical Oncology
August/8/2001
Abstract
A newly approved oral fluoropyrimidine, TS-1, is a dihydropyrimide dehydrogenase (DPD)-inhibiting fluoropyrimidine (DIF) drug. We describe a case of interstitial pneumonia probably caused by TS-1. A peripheral blood lymphocytes stimulating test (DLST) with TS-1 demonstrated a substantial positive reaction. So far only three cases of TS-1-induced interstitial pneumonia have been reported but the relationship between interstitial pneumonia and TS-1 was demonstrated only in this case. Considering that interstitial pneumonia has also been reported with 5-FU, it is necessary in the future to clarify which component of this drug is directly related to interstitial pneumonia.
Publication
Journal: Ophthalmic Epidemiology
September/24/2008
Abstract
OBJECTIVE
To assess and re-engineer the Vision Core Measure 1 (VCM1) questionnaire in low vision (LV) and cataract participants using Rasch analysis.
METHODS
295 participants drawn from a low vision clinic and 181 from a cataract surgery waiting list completed the 10-item VCM1. Unidimensionality, item fit to the model, response category performance, differential item functioning (DIF) and targeting of items to patients were assessed. Category collapsing and item removal were considered to improve the questionnaire.
RESULTS
The initial fit of the VCM1 (combined populations) to the Rasch model showed lack of fit (chi2 = 83.3, df = 50, p = 0.002). There was evidence of DIF between the two populations which could not be resolved. Consequently, each population was assessed separately. Irrespective of the population, disordering of response category thresholds was evident. However, collapsing categories produced ordered thresholds and resulted in fit to the Rasch model for the LV (Total chi2 = 41.6, df = 30; p = 0.08) and cataract population (Total chi2 = 17.9, df = 20, p = 0.59). Overall, the VCM1 behaved as a unidimensional scale for each population and no item showed evidence of DIF. Item targeting to patients was however sub-optimal particularly for the cataract population.
CONCLUSIONS
The VCM1 questionnaire could be improved by shortening the response scale, although different response categories are required for cataract and LV populations. Calibration of items also differed across populations. While the VCM1 performs well within the Rasch model, in line with its initial purpose, it requires the addition of items to satisfactorily target low vision and cataract populations.
Publication
Journal: PLoS ONE
September/10/2017
Abstract
This study had two aims. Firstly, the psychometric properties of the 20-item Toronto Alexithymia Scale (TAS-20) and the Alexithymia Questionnaire for Children (AQC) that measure the three dimensions of alexithymia (DIF, difficulty identifying feelings; DDF, difficulty describing feelings; EOT, externally-oriented thinking) were explored in various samples of children, adolescents or young adults to detect the best factor-structure and to examine if the Externally-Oriented Thinking (EOT) factor must be deleted or not. Secondly, the capacity for adolescents to distinguish between alexithymia and depression was studied using factorial analyses of items of self-report of alexithymia and depression scales. Four groups were examined (80 healthy children, 105 adolescents with various psychiatric disorders, 333 healthy older adolescents and 505 young adults recruited from universities). The first two groups filled out the AQC and the latter two the TAS-20. Confirmatory factorial analyses (CFA) showed that the two-factor model (DIF, DDF) provided acceptable fits and had significant advantages over the three-factor model (DIF, DDF, EOT). Low alpha coefficients for the EOT subscale were reported (range from 0.18-0.61). Except for the children sample, exploratory factorial analyses (EFA) were performed on the items of the TAS-20 or AQC without the EOT items and the Beck depression inventory-II (BDI-II) or the Zung Self-Rating Depression Scale (SDS). The items of the AQC and BDI-II or items of the TAS-20 and SDS loaded on separate factors with only a minor overlap suggesting that adolescents were able to differentiate alexithymia and depression when self-assessments were used. Alexithymia can be reliably assessed in adolescents using the TAS-20 or AQC without the eight items rating the EOT dimension.
Publication
Journal: Journal of the American Academy of Dermatology
May/31/2019
Abstract
Non-scarring alopecia in systemic lupus erythematosus (SLE) is widely recognized but reports on its clinical, trichoscopic, histopathological and direct immunofluorescence (DIF) features are still limited.To summarize the different clinical patterns, trichoscopic, histopathological and DIF features of non-scarring alopecia in SLE, as well as proving its association with disease activity.SLE patients with and without non-scarring alopecia underwent full physical/trichoscopic examination and scalp biopsy. Their disease activity scores and laboratory data were evaluated and statistically analyzed.Thirty-two SLE patients had different patterns of non-scarring alopecia including: mild diffuse alopecia, severe diffuse alopecia, patchy alopecia and lupus hair. The most common trichoscopic findings were arborizing/interconnecting vessels (81.3%). Histopathological examination revealed interface changes along the dermoepidermal junction (DEJ) (87.5%) and follicular epithelium (40.6%). On DIF, homogeneous granular deposition was detected along the DEJ (78.1%) and follicular epithelium (78.1%). When compared to 10 SLE patients without alopecia, there was a significantly higher SLE Disease Activity Index 2000 score and prevalence of proteinuria (>1g/day).This was a small, cross-sectional, single-center study.Non-scarring alopecia in SLE reveals lupus erythematosus-specific changes on histology and DIF. Hair loss in SLE can be considered as an indicator of active disease.
Publication
Journal: Journal of Psychosomatic Research
December/31/2014
Abstract
OBJECTIVE
The aim of this paper is to provide new insights into the psychometrics of the Quality of Life in Adult Cancer Survivors (QLACS) questionnaire, originally developed for longer-term survivors 5+years post-diagnosis. Specifically, to examine the classic psychometric properties of QLACS in a sample of shorter-term survivors, and to undertake Rasch analysis to explore the extent to which the Generic and Cancer-Specific summary scales (and separately-analysed Benefits of cancer domain) are unidimensional, with linear measurement properties and no differential item functioning (DIF).
METHODS
Patients with potentially curable breast, colorectal or prostate cancer completed QLACS 15 months post-diagnosis (N=407). Score distributions, floor and ceiling effects, internal reliability, and feasibility (completion time and missing data) were examined. Rasch analysis included examination of item fit, DIF and unidimensionality.
RESULTS
The QLACS domains and summary scales had very similar score distributions and classic psychometric properties (no ceiling effects, majority no floor effects, acceptable reliability) to those found in development work with longer-term survivors. Median completion time was 10 min and total missing data 2.3%. The Generic summary scale contained several misfitting items and exhibited multidimensionality. The Cancer-Specific summary scale and Benefits domain showed fit to the Rasch model and demonstrated unidimensionality and no DIF, with just one or no item modifications respectively.
CONCLUSIONS
QLACS demonstrates similarly good classic psychometric properties among shorter-term as among longer-term survivors, and has good feasibility. The Cancer-Specific summary scale and Benefits domain showed an impressive degree of fit to the Rasch model, although the validity of computing the Generic summary score was not supported.
Publication
Journal: PLoS ONE
May/5/2016
Abstract
The Dutch-Flemish PROMIS Group translated the adult PROMIS Pain Interference item bank into Dutch-Flemish. The aims of the current study were to calibrate the parameters of these items using an item response theory (IRT) model, to evaluate the cross-cultural validity of the Dutch-Flemish translations compared to the original English items, and to evaluate their reliability and construct validity. The 40 items in the bank were completed by 1085 Dutch chronic pain patients. Before calibrating the items, IRT model assumptions were evaluated using confirmatory factor analysis (CFA). Items were calibrated using the graded response model (GRM), an IRT model appropriate for items with more than two response options. To evaluate cross-cultural validity, differential item functioning (DIF) for language (Dutch vs. English) was examined. Reliability was evaluated based on standard errors and Cronbach's alpha. To evaluate construct validity correlations with scores on legacy instruments (e.g., the Disabilities of the Arm, Shoulder and Hand Questionnaire) were calculated. Unidimensionality of the Dutch-Flemish PROMIS Pain Interference item bank was supported by CFA tests of model fit (CFI = 0.986, TLI = 0.986). Furthermore, the data fit the GRM and showed good coverage across the pain interference continuum (threshold-parameters range: -3.04 to 3.44). The Dutch-Flemish PROMIS Pain Interference item bank has good cross-cultural validity (only two out of 40 items showing DIF), good reliability (Cronbach's alpha = 0.98), and good construct validity (Pearson correlations between 0.62 and 0.75). A computer adaptive test (CAT) and Dutch-Flemish PROMIS short forms of the Dutch-Flemish PROMIS Pain Interference item bank can now be developed.
Publication
Journal: Quality of Life Research
September/10/2018
Abstract
BACKGROUND
The Patient-Reported Outcomes Measurement Information System (PROMIS) item banks 'Ability to Participate in Social Roles and Activities' (35 items) and 'Satisfaction with Social Roles and Activities' (44 items) were developed to measure (satisfaction with) participation more efficiently and precisely than current instruments, by using Computerized Adaptive Testing (CAT). We validated these item banks in a Dutch general population.
METHODS
Participants in an internet panel completed both item banks. Unidimensionality, local dependence, monotonicity, Graded Response Model item fit, Differential Item Functioning (DIF) for age, gender, education, region, ethnicity, and language (Dutch compared to US Social Supplement), and reliability were assessed.
RESULTS
A representative Dutch sample of 1002 people participated. We found for the Ability to Participate and Satisfaction with Participation item banks, respectively, sufficient unidimensionality (CFI: 0.971, 0.960; TLI: 0.970, 0.958; RMSEA: 0.108, 0.108), no local dependence, sufficient monotonicity (H: 0.75, 0.73), good item fit (2 out of 35 items, 1 out of 44 items with S-X2 p-value < 0.001). No DIF was found. We found a reliability of at least 0.90 with simulated CATs in 86% and 94% of the participants with on average 4.7 (range 2-12) and 4.3 (range 3-12) items, respectively.
CONCLUSIONS
The PROMIS participation item banks showed sufficient psychometric properties in a general Dutch population and can be used as CAT. PROMIS CATs allow reliable and valid measurement of participation in an efficient and user-friendly way with limited administration time.
Publication
Journal: Psychiatry Research
June/1/2011
Abstract
The aim of the present study was to explore the associations of perceived social support and parental attitude with alexithymia in a Finnish adolescent population sample. Of the initial sample of 935 adolescents, 729 (78%) answered the questionnaire and formed the final sample. The mean age of the subjects was 19 years (range 17-21 years). The 20-item Toronto Alexithymia Scale (TAS-20) was used for assessment of alexithymia. Perceived social support from family, friends, and significant other people was measured using the Multidimensional Scale of Perceived Social Support (MSPSS). Perceived parental care and overprotection were assessed using the Parental Bonding Instrument (PBI), and separately for mother and father. After controlling for the sociodemographic factors, alexithymia was significantly associated with a lower degree of experienced social support and higher parental overprotection both in females and males. Maternal overprotection was associated (p<0.04) with TAS-20 total score as well as the Difficulty Identifying Feelings (DIF) and Difficulty Describing Feelings (DDF) subscales. The lack of social support from friends appeared to predict alexithymia more strongly than lack of support from family and significant other people. Against our hypothesis, maternal and paternal care was not directly associated with alexithymic features. This study highlights the significance of intrusive and overprotective parental attitudes as a possible risk factor for development of alexithymia. However, to assess causality, we need longitudinal studies. The results also emphasize the need for further studies to establish the significance of peer relationships in the development of alexithymia.
Publication
Journal: Papua and New Guinea medical journal
October/9/1995
Abstract
The first multicentre survey of sexually transmitted diseases (STDs) performed in Papua New Guinea was conducted in STD clinics in five towns, Port Moresby, Goroka, Rabaul, Lae and Daru, from September 1989 to May 1990. Infections with Neisseria gonorrhoeae and Chlamydia trachomatis (alone or in combination) were common. Penicillinase-producing N. gonorrhoeae (PPNG) represented 44% of all gonococcal isolates but significant intrinsic resistance to penicillin was not found. Of the other antibiotics tested, significant elevation of minimum inhibitory concentration (MIC) was common only for tetracycline, although no high-level tetracycline resistance was detected. C. trachomatis was detected by direct immunofluorescence (DIF) in 26% of 210 males and 27% of 64 females. 10% (21/210) of males and 11% (7/64) of females were both DIF positive for C. trachomatis and culture positive for N. gonorrhoeae. Of 203 males and 78 females tested, 5% and 12%, respectively, had serological evidence of current syphilis infection. Clinically, genital ulcer disease was most commonly due to syphilis, donovanosis or genital herpes, while specific vaginal infections were commonly seen in female patients attending Port Moresby and Lae STD clinics.
Publication
Journal: Journal of Cardiovascular Nursing
August/30/2017
Abstract
BACKGROUND
The 9-item European Heart Failure Self-Care Behavior scale (EHFScB-9) is a self-reported questionnaire commonly used to capture the self-care behavior of people with heart failure (HF).
OBJECTIVE
The aim of this study was to investigate the EHFScB-9's factorial structure and categorical functioning of the response scale and differential item functioning (DIF) across subpopulations in Iran.
METHODS
Patients with HF (n = 380; 60.5% male; mean [SD] age, 61.7 [9.1] years) participated in this study. The median (interquartile range) of the duration of their HF was 6.0 (2.4-8.8) months. Most of the participants were in New York Heart Association classification II (NYHA II, 61.8%); few of them had left ventricular ejection fraction assessment (11.3%). All participants completed the EHFScB-9. Confirmatory factor analysis was used to test the factorial structure of the EHFScB-9; Rasch analysis was used to analyze categorical functioning and DIF items across 2 characteristics (gender and NYHA).
RESULTS
The 2-factor structure ("adherence to regimen" and "consulting behavior") of the EHFScB-9 was confirmed, and the unidimensionality of each factor was found. Categorical functioning was supported for all items. No items displayed substantial DIF across gender (DIF contrast, -0.25-0.31). Except for item 3 ("Contact doctor or nurse if legs/feet are swollen"; DIF contrast, -0.69), no items displayed substantial DIF across NYHA classes (DIF contrast, -0.40 to 0.47).
CONCLUSIONS
Despite the DIF displayed in 1 item across the NYHA classes, the EHFScB-9 demonstrated sound psychometric properties in patients with HF.
Publication
Journal: PLoS ONE
November/13/2018
Abstract
OBJECTIVE
To investigate whether items of the SF-12, widely used to assess health outcome in clinical practice and public health research, provide unbiased measurements of underlying constructs in different demographic groups regarding gender, age, educational level and ethnicity.
METHODS
We included 23,146 men and women aged 18-70 of Dutch, South-Asian Surinamese, African Surinamese, Ghanaian, Turkish, or Moroccan origin from the HELIUS study. Both multiple group confirmatory factor analyses (MGCFA), with increasingly stringent model constraints (i.e. assessing Configural, Metric, Strong and Strict measurement invariance (MI)), and regression analysis were conducted to establish comparability of SF-12 items across demographic groups.
RESULTS
MI regarding gender, age and education was tested in the ethnic Dutch group (N = 4,615). In each subsequent step of testing MI, change in goodness-of-fit measures did not exceed 0.010 (RMSEA) or 0.004 (CFI). Moreover, goodness-of-fit indices showed good fit for strict invariance models: RMSEA<0.055; CFI>0.97. Regarding ethnicity, RMSEA values of metric and subsequent models fell above 0.055, indicating violation of measurement invariance in factor loadings, thresholds and residual variances. Regression analysis revealed possible age-, education- and ethnicity-related DIF. Adjustment for this DIF had little impact on the magnitude of age and educational differences in physical and mental health, but ethnic inequalities in physical health-and to a lesser extent mental health-were reduced after DIF adjustment.
CONCLUSIONS
We found no evidence of violation of measurement invariance of the SF-12 regarding gender, age and educational level. If minor DIF would remain undetected in our MGCFA analyses, we showed that this would have negligible effect on the magnitude of demographic health inequalities. Regarding ethnicity, the SF-12 was not measurement invariant. After accounting for DIF, we observed a reduction of ethnic inequalities in health, in particular in physical health. Caution is warranted when comparing SF-12 scores across population groups with various ethnic backgrounds.
Publication
Journal: PLoS ONE
April/22/2015
Abstract
OBJECTIVE
To develop and validate a Chinese version of the Catquest-9SF questionnaire in a cataract population.
METHODS
The Catquest-9SF Questionnaire was translated and back translated into Chinese. Preoperative patients were recruited at a tertiary eye hospital and their demographic information and visual acuity were documented. Psychometric properties of the Catquest-9SF, including ordered thresholds, the ability to distinguish between different strata of person ability, absence of misfitting items, unidimentionality, differential item functioning (DIF) and construct validity were tested, using Rasch analysis.
RESULTS
A total of 102 patients (100% response rate) were enrolled. The participants'mean age was 70.2 year (SD = 12.1) and 46.9% were female. Rasch analysis showed that this version of the questionnaire had ordered response thresholds and was free of DIF. The items fit a single overall construct and unidimensional by principal components analysis of the residuals. Patients with visual impairment had significantly poorer Rasch scores on the Catquest-9SF (mean change, -2.5, p = 0.035, compared with non-visually impaired patients).
CONCLUSIONS
The Chinese version of Catquest-9SF is a valid and reliable questionnaire for assessing the visual disability outcomes of Chinese patients with cataract, and it may be recommended for routine clinical use.
Publication
Journal: Open Neurology Journal
December/11/2012
Abstract
Laboratory based diagnosis of infectious diseases usually relies on culture of the disease causing micro-organism, followed by identification and susceptibility testing. Since Borrelia burgdorferi sensu lato, the etiologic agent of Lyme disease or Lyme borreliosis, requires very specific culture conditions (e.g. specific liquid media, long term cul-ture) traditional bacteriology is often not done on a routine basis. Instead, confirmation of the clinical diagnosis needs ei-ther indirect techniques (like serology or measurement of cellular activity in the presence of antigens) or direct but culture independent techniques, like microscopy or nucleic acid amplification techniques (NAT), with polymerase chain reaction (PCR) being the most frequently applied NAT method in routine laboratories. NAT uses nucleic acids of the disease causing micro-organism as template for amplification, isolated from various sources of clinical specimens. Although the underlying principle, adoption of the enzymatic process running during DNA duplication prior to prokaryotic cell division, is comparatively easy, a couple of 'pitfalls' is associated with the technique itself as well as with interpretation of the results. At present, no commercial, CE-marked and sufficiently validated PCR assay is available. A number of homebrew assays have been published, which are different in terms of target (i.e. the gene targeted by the amplification primers), method (nested PCR, PCR followed by hybridization, real-time PCR) and validation criteria. Inhibitory compounds may lead to false negative results, if no appropriate internal control is included. Carry-over of amplicons, insufficient handling and workflow and/or insufficiently validated targets/primers may result in false positive results. Different targets may yield different analytical sensitivity, depending, among other factors, of the redundancy of a target gene in the genome. Per-formance characteristics (e.g. analytical sensitivity and specificity, clinical sensitivity and specificity, reproducibility, etc.) are, if available, only applicable to a specific assay, running in a specific laboratory. Finally, not only the NAT/PCR method itself, but also the process of DNA isolation from the specimen, is highly diverse and may have fundamental im-pact on the (expected) PCR result. Of concern are distribution effects of DNA, in particular, if only low numbers of bacte-ria/genomes are present in a sample, as it is the case for instance in cerebrospinal fluids. For the ordering physician and for the patient requesting PCR analysis, these 'pitfalls' are usually invisible. As a conse-quence, the reported result (i.e. PCR negative or positive for B. burgdorferi) is hard to interpret, especially, if the reported PCR result is contradictory to the clinical diagnosis or other laboratory findings. Moreover, due to the high number of dif-ferent assays in use, two laboratories, testing the same specimen, might come to different PCR results. The current paper wants to summarize the available PCR/NAT assays for the detection of B. burgdorferi DNA in clinical specimens, with special attention to neurologic disorders, and to discuss the difficulties in PCR analysis and result inter-pretation, associated thereof. In view of growing numbers of patients who are diagnosed of having Lyme disease, and ac-knowledging a substantial growth in knowledge regarding other tick- or vector-borne pathogens, which might be able to induce symptoms comparable to Lyme (neuro-)borreliosis, efforts are urgently needed to standardize and harmonize methods for B. burgdorferi nucleic acid amplification.
Publication
Journal: International Journal of Dermatology
April/28/2009
Abstract
Enzyme-linked immunosorbent assay (ELISA) is an excellent tool for detection of circulating antibodies against the NC16A portion of BP180 antigen. We compared the sensitivity and specificity of a commercially available BP180-NC16a domain ELISA with that of an indirect immunofluorescence (IIF) testing in the evaluation of bullous pemphigoid (BP) and pemphigoid gestationis (PG), and analyzed the relationship between ELISA results and the presence of IgG deposition, in an epidermal or combined pattern, on direct immunofluorescence (DIF) testing of salt-split skin. ELISA was performed on serum from 28 patients (24 BP, 4 PG) and 50 controls. IIF testing was performed on serum from 27 patients and 98 controls. For the group of 28 patients with BP or PG, ELISA had a sensitivity of 93% and specificity of 96% (P < 0.001), while sensitivity was 74% and specificity 96% (P < 0.001) for IIF testing. In these patients, ELISA has a higher sensitivity than IIF testing, but similar specificity. Evaluation of controls who had IgG deposition on the dermal side of salt-split skin on DIF testing showed specificity for the ELISA of 100% (all four cases negative) and 80% for IIF testing (one of five positive). Positive ELISA correlated with a diagnosis of BP or PG only in patients who had IgG at the basement membrane zone (BMZ) by DIF testing. Overall, ELISA appears to have greater sensitivity and specificity for BP or PG than does IIF testing.
Publication
Journal: PLoS ONE
December/10/2019
Abstract
This study aimed to assess the effect of diurnal intermittent fasting (DIF) during and outside of the month of Ramadan on plasma levels of interleukin (IL)-1β, IL-6, and IL-8, while controlling for sleep/wake pattern, sleep length and quality, meal composition, energy consumption and expenditure, and light exposure. DIF outside of the month of Ramadan was performed to evaluate the effect of DIF in the absence of the way of life accompanying Ramadan.Twelve healthy male volunteers with a mean age of 25.1 ± 2.5 years arrived to the sleep laboratory on 4 times: 1) adaptation, 5 weeks before Ramadan; 2) 4 weeks before Ramadan while performing DIF for 1 week (fasting outside of Ramadan; FOR); 3) 1 week before Ramadan (non-fasting baseline; non-fasting BL); and 4) After completing 2 weeks of Ramadan while performing DIF. Plasma levels of cytokines were assessed using enzyme-linked immunoassays at 22:00, 02:00, 04:00, 06:00, and 11:00.During DIF, there was a significant decrease in the levels of cytokines, particularly, IL-1β and IL-6, in most measurements compared to non-fasting BL. This reduction was more obvious during the FOR period. There were no significant changes in the circadian phase of the measured cytokines reflected by the acrophase of the measured variables during fasting (FOR and Ramadan) compared to non-fasting BL.Under controlled conditions, DIF led to significantly decreased plasma levels of cytokines (IL-1β, IL-6, and IL-8), particularly IL-1β and IL-6 across 24 h. DIF had no effect on the circadian patterns of the measured cytokines as shown by cosinor analysis.
Publication
Journal: Journal of Pharmacy and Pharmacology
September/9/2014
Abstract
OBJECTIVE
Interactions between drugs and polymers were utilized to lower the processing temperature of hot-melt extrusion (HME), and thus minimize the thermal degradation of heat-sensitive drugs during preparation of amorphous solid dispersions.
METHODS
Diflunisal (DIF), which would degrade upon melting, was selected as a model drug. Hydrogen bonds between DIF and polymeric carriers (PVP K30, PVP VA64, hydroxypropyl methylcellulose and Soluplus) were revealed by differential scanning calorimetry and Fourier transform infrared spectroscopy. The hot-melt extruded solid dispersion was characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-performance liquid chromatography (HPLC).
RESULTS
The results of hot-stage polar microscopy indicated that DIF was dissolved in molten polymers at 160°C, much lower than the melting point of DIF (215°C). At this temperature, amorphous solid dispersions were successfully produced by HME, as confirmed by XRD and SEM. The related impurities in amorphous solid dispersions detected by HPLC were lower than 0.3%, indicating that thermal degradation was effectively minimized. The dissolution of DIF from amorphous solid dispersions was significantly enhanced as compared with the pure crystalline drug.
CONCLUSIONS
This technique based on drug-polymer interactions to prepare chemically stable amorphous solid dispersions by HME provides an attractive opportunity for development of heat-sensitive drugs.
Publication
Journal: Lupus
November/16/2015
Abstract
Bullous systemic lupus erythematosus has rarely been described in pediatric lupus population and the real prevalence of childhood-onset bullous systemic lupus erythematosus has not been reported. From January 1983 to November 2013, 303 childhood-onset SLE (c-SLE) patients were followed at the Pediatric Rheumatology Unit of the Childreńs Institute of Hospital das Clínicas da Faculdade de Medicina Universidade da Universidade de São Paulo, three of them (1%) diagnosed as childhood-onset bullous systemic lupus erythematosus. All three cases presented tense vesiculobullous lesions unassociated with lupus erythematosus lesions, with the median duration of 60 days (30-60). All patients fulfilled bullous systemic lupus erythematosus criteria. Two had nephritis and serositis and presented specific autoantibodies. The histological pattern demonstrated subepidermal blisters with neutrophils-predominant infiltrates within the upper dermis. Direct immunofluorescence (DIF) showed deposits of IgG and complement along the epidermal basement membrane, in the presence or absence of IgA and/or IgM. A positive indirect immunofluorescence on salt-split skin demonstrating dermal binding was observed in two cases. All of them had moderate/severe disease activity at diagnosis with median Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) of 18 (14-24). Two patients received dapsone and one with severe nephritis received immunosuppressive drugs. In conclusion, in the last 30 years the prevalence of bullous lupus in childhood-onset lupus population was low (1%) in our tertiary University Hospital. A diagnosis of SLE should always be considered in children with recurrent tense vesiculobullous lesions with or without systemic manifestations.
Publication
Journal: Scandinavian Journal of Occupational Therapy
August/24/2009
Abstract
This study investigated psychometric properties of an instrument for assessing perceived occupational value, the 26-item OVal-pd. Data from 225 Swedish subjects with and without known mental illness were analysed regarding fit to the Rasch measurement model (partial credit model), differential item functioning (DIF), and functioning of the OVal-pd four-category response scale. The reliability (index of person separation, analogous to Cronbach's alpha) was good (0.92) but there were signs of overall and item level (six items) misfit. There was DIF between people with and without mental illness for three items. Iterative deletion of misfitting items resulted in a new 18-item DIF-free scale with good overall and individual item fit and maintained reliability (0.91). There were no disordered response category thresholds. These observations also held true in separate analyses among people with and without mental illness. Thus, the first steps of ensuring that occupational value can be measured in a valid and reliable way have been taken. Still, occupational value is a dynamic construct and the aspects that fit the construct may vary between contexts. This has implications for, e.g., cross-cultural research and calls for identification of a core set of culture-free items to allow for valid cross-cultural comparisons.
Publication
Journal: Journal of General Internal Medicine
October/4/2015
Abstract
BACKGROUND
There is limited information on depression in Haitians and this is partly attributable to the absence of culturally and linguistically adapted measures for depression.
OBJECTIVE
To perform a psychometric evaluation of the Haitian-Creole version of the PHQ-9 administered to men who have sex with men (MSM) in the Republic of Haiti.
METHODS
This study uses a cross-sectional design and data are from the Integrated Behavioral and Biological HIV Survey (IBBS) for MSM in Haiti.
METHODS
Inclusion criteria required that participants be male, ≥ 18 years, report sexual relations with a male partner in the last 12 months, and lived in Haiti during the past 3 months. Respondent Driven Sampling was used for participant recruitment.
METHODS
A structured questionnaire was verbally administered in Haitian-Creole capturing information on sociodemographics, sexual behaviors, human immunodeficiency virus (HIV) status and depressive symptomatology using the PHQ-9. Psychometric analyses of the translated PHQ-9 assessed unidimensionality, factor structure, reliability, construct validity, and differential item functioning (DIF) across subgroups (age, educational level, sexual orientation and HIV status).
RESULTS
In a study population of 1,028 MSM, the Haitian-Creole version of the PHQ-9 is unidimensional, has moderately high internal consistency reliability (α = 0.78), and shows evidence of construct validity where HIV-positive subjects have greater depression (p = 0.002). There is no evidence of DIF across age, education, sexual orientation or HIV status. HIV-positive MSM are twice as likely to screen positive for moderately severe and severe depressive symptoms compared to their HIV-negative counterparts.
CONCLUSIONS
There is strong evidence for the psychometric adequacy of the translated PHQ-9 screening tool as a measure of depression with MSM in Haiti. Future research is necessary to examine the predictive validity of depression for subsequent health behaviors or clinical outcomes among Haitian MSM.
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