Light-induced skin lesions in lupus erythematosus: photobiological studies

Summary To investigate the light sensitivity to various wavelength regions in lupus erythematosus (LE), phototests were performed in 24 LE patients with clinical photosensitivity (7 had systemic LE, 9 discoid LE, and 8 subacute cutaneous LE). Skin areas (measuring 40–60 cm²) were irradiated daily, maximally six times. With all three light sources used (emitting UVB, UVA, and visible light respectively) abnormal papular or papulosquamous reactions could be induced. In four of the 20 patients reacting abnormally, lesions occurred 10 or more days after cessation of the phototests; this indicates that the problem of photosensitivity in LE may be greater than appreciated so far.     

Binding of antibodies to nonhistone nucleoproteins on keratinocytes in suspensions

Summary Antibody binding on the cell surface of epidermal cells, recently established on cultured neonatal foreskin cells, is supposed to play a role in the pathogenesis of in vivo antinuclear antibodies (ANA) of the skin. To study this phenomenon in suspensions of adult human keratinocytes, a cell system more closely related to the in vivo situation, we investigated the binding capacity of nine sera with various antibody profiles against nuclear components, as well as a murine monoclonal Sm-antibody. It was found that sera containing antibodies against nonhistone nucleoproteins bound to the cell surface of keratinocytes, whereas monospecific anti-dsDNA sera and the murine anti-Sm serum did not. This binding was found in both basal and suprabasal keratinocytes. The percentage of cells showing antibody binding was not significantly enhanced by preirradiation with ultraviolet light, as was found in a previously study. The cell surface binding is probably an antigen-antibody binding and not the result of cross-reactivity. Such cell surface binding may be important for the formation of in vivo ANA in the skin.     

In vivo antinuclear antibody of the skin: diagnostic significance and association with selective antinuclear antibodies.

Immunofluorescence microscopy of the skin has disclosed antibodies bound to epidermal cell nuclei in several connective tissue disorders. To establish the diagnostic potential of this phenomenon the results of immunofluorescence microscopy of biopsy specimens from 1651 subjects with various diseases and from 315 patients with systemic connective tissue disorders and related diseases were reviewed. It was found that the predictive value of the phenomenon for the presence of a systemic connective tissue disorder was, in general, 88%. Except for the homogeneous and thready patterns, which seldom appear, but are specific for SLE, in vivo antinuclear antibody (ANA) does not discriminate better between the various disorders than do serum antibodies. The presence of in vivo ANA in the skin was related to serum antibodies against non-histone nucleoproteins, but not to anti-dsDNA antibodies. Combined with the finding that antibodies against non-histone nucleoproteins can bind on the surface of human keratinocytes, this suggests that ANA of the skin occurs in vivo.     

Preimplantation genetic screening reveals a high incidence of aneuploidy and mosaicism in embryos from young women undergoing IVF

BACKGROUND: In order to assess the frequency of aneuploidy and mosaicism in embryos obtained from IVF patients aged <38 years, preimplantation genetic screening (PGS) was performed after biopsy of two blastomeres. Furthermore, the reliability of this diagnosis was assessed by performing reanalysis of the embryo on day 5. METHOD: The copy numbers of 10 chromosomes (1, 7, 13, 15, 16, 18, 21, 22, X and Y) were investigated by fluorescence in situ hybridization (FISH) analysis. Embryos that were found to be abnormal or of insufficient morphological quality were cultured until day 5 and reanalysed. Results obtained were compared to the day 3 blastomere analysis. RESULTS: After analysis of 196 embryos (one cell in 38% and two cells in 62%), only 36% of the embryos were found to be normal on day 3. After analysis of two blastomeres, 50% showed chromosomal mosaicism. Comparison of the FISH results from day 3 blastomeres and day 5 embryos yielded an overall cytogenetic confirmation rate of 54%. CONCLUSIONS: The rates of mosaicism and aneuploidy in these embryos from young IVF patients are similar to those published for older women. We found the best confirmation rate after a diagnosis based on two cells, where both blastomeres showed the same chromosomal abnormality. In contrast, after a mosaic diagnosis the confirmation rate was low. The present study provides the first detailed reanalysis data of embryos analysed by PGS and clearly demonstrates the impact of mosaicism on the reliability of the PGS diagnosis.     

Fluorescence in situ hybridization analysis of two blastomeres from day 3 frozen-thawed embryos followed by analysis of the remaining embryo on day 5

BACKGROUND: Chromosomal mosaicism in human embryos may give rise to false positive or false negative results in preimplantation genetic diagnosis for aneuploidy screening (PGD-AS). Therefore, we have investigated whether the results obtained from a 2-cell biopsy of frozen-thawed embryos and fluorescence in situ hybridization (FISH) analysis are representative for the chromosome constitution of the remaining embryo on day 5. METHODS: Cryopreserved day 3 embryos were thawed and from surviving embryos two blastomeres were biopsied. FISH analysis was performed for chromosomes 1, 7, 13, 15, 16, 18, 21, 22, X and Y. After biopsy, the embryos were cultured until day 5 and further analysed using the same probe panels. RESULTS: In all, 17 embryos were available with a diagnosis based on two blastomeres on day 3 and confirmatory studies on day 5. In 10 of these 17 cases the initial diagnosis could be confirmed. However, in only six cases cytogenetic results were concordant. Besides the 10 cases with a 'correct' diagnosis, there were six false positive results and one false negative, all involving mosaicism. CONCLUSIONS: Investigating the chromosomal constitution of two blastomere nuclei offers a good opportunity to study the incidence of chromosomal mosaicism in early embryo development. The confirmation rate of the results obtained on day 3 depends on the interpretation and is higher when considered from a clinical than from a cytogenetic point of view.     

Joint models for longitudinal and time-to-event data in a case-cohort design

Studies with longitudinal measurements are common in clinical research. Particular interest lies in studies where the repeated measurements are used to predict a time-to-event outcome, such as mortality, in a dynamic manner. If event rates in a study are low, however, and most information is to be expected from the patients experiencing the study endpoint, it may be more cost efficient to only use a subset of the data. One way of achieving this is by applying a case-cohort design, which selects all cases and only a random samples of the noncases. In the standard way of analyzing data in a case-cohort design, the noncases who were not selected are completely excluded from analysis; however, the overrepresentation of the cases will lead to bias. We propose to include survival information of all patients from the cohort in the analysis. We approach the fact that we do not have longitudinal information for a subset of the patients as a missing data problem and argue that the missingness mechanism is missing at random. Hence, results obtained from an appropriate model, such as a joint model, should remain valid. Simulations indicate that our method performs similar to fitting the model on a full cohort, both in terms of parameters estimates and predictions of survival probabilities. Estimating the model on the classical version of the case-cohort design shows clear bias and worse performance of the predictions. The procedure is further illustrated in data from a biomarker study on acute coronary syndrome patients, BIOMArCS.     

Dental students on instruction in local anaesthesia

In order to find out how dental students feel about their education in the application of local anaesthesia, a questionnaire was distributed via e-mail among all dental students in the Netherlands. A total of 397 completed questionnaires were analyzed statistically. At all 3 dental schools in the second year instruction in theoretical aspects of local anaesthesia began. Practical teaching began in the second or third study year. A preclinical training model was used by 15% of the students in Amsterdam, 20% of the students in Nijmegen and 35% of the students in Groningen. When they administered their first injection in a human, a fellow dental student in 91-98% of all cases, 24-74% of the students felt that they were insufficiently prepared. 35-52% of the students said that they would also like to receive instruction in intraligamentary anaesthesia in the dental curriculum. Other changes in the curriculum were also frequently suggested, especially the introduction of preclinical training models (29%, 55% and 56% for Groningen, Nijmegen and Amsterdam respectively).