DMSO reduces CSF-1 receptor levels and causes apoptosis in v-myc immortalized mouse macrophages.

We have investigated the antiproliferative potentialof dimethyl sulfoxide (DMSO) on v-myc immortalized mouse macrophages on account of the cytotoxic effect induced by DMSO on myeloid cells. DMSO caused significant apoptosis in two immortalized macrophage celllines constitutively secreting colony-stimulating factor 1 (CSF-1). In contrast to the results described for mouse erythroleukemia cells, DMSO did not markedly decrease the level of the Spi-1/PU.1 transcription factor. However, DMSO caused a specific reduction in the protein level of the CSF-1 receptor (CSF-1R) compared to the FcgammaRIIIA immunoglobulin receptor, v-myc, and beta-actin proteins. To investigate if the level of CSF-1R might inversely correlate with DMSO-induced cell death, we derived a macrophage culture (named DN-11) that could be cultured in the presence of DMSO. Immunoblot analysis of DN-11, grown with or without DMSO, revealed significant amounts of CSF-1R under both conditions, suggesting a pivotal role for CSF-1R in the survival of DMSO-treated macrophages. Therefore, in these cells, DMSO seems to trigger apoptosis by interrupting an autocrine survival loop involving the CSF-1 receptor.

Isolation and characterization of a chicken homologue of the Spi-1/PU.1 transcription factor.

Spi-1/PU.1 is a member of the Ets family of transcription factors important in regulation of hematopoiesis. We have isolated a chicken cDNA homologuous to the mammalian Spi-1/PU.1 gene with an open reading frame of 250 amino acids (aa). The chicken Spi-1/PU.1 protein is 14 aa and 16 aa shorter than its human and mouse counterparts but is extremely well conserved with 78.8% and 75.2% identity respectively. The carboxy terminal DNA binding region, or ETS binding domain, is 100% identical to that of human and mouse. Some differences with the mammalian homologues are seen in the N-terminal part of the protein and in the PEST connecting domain. However, the differences are mainly conservative and all the features underlying functional aspects seem preserved. The major discrepancy lies in a 12 aa deletion in an already poorly conserved part of the PEST sequence. Spi-1/PU.1 transcripts were detected at high levels in spleen and Fabricius bursa of chick embryos by Northern blot and in situ hybridization. Our results show that the chicken Spi-1/PU.1 protein behaves like a bonafide Spi-1/PU.1 transcription factor in its DNA binding and transactivating properties.

Hydrocortisone modulates the expression of c-ets-1 and 72 kDa type IV collagenase in chicken dermis during early feather morphogenesis.

At the onset of chicken feather morphogenesis, dermal cells migrate along bundles of collagen fibers to colonize areas where bud outgrowth takes place. Chicken embryos treated with hydrocortisone during the critical phase of dermal rearrangement show featherless skin areas in which the dermis exhibits an increase of interstitial collagen. We had previously demonstrated that c-ets-1 is a nuclear transcription factor expressed in the dermis at the beginning of feather morphogenesis. Here we study, by in situ mRNA hybridization, the expression of c-ets-1 in the dermis of chicken embryos treated with hydrocortisone. We found that, among the two distinct products (p54 and p68) encoded by the chicken c-ets-1, the expression of the p68 product increased while expression of p54 decreased after hydrocortisone treatment. Since Ets-1 regulates matrix-metalloproteinases genes, we analyzed the expression of the 72 kDa type IV collagenase in both normal and hydrocortisone-treated embryos. We demonstrated that 72 kDa type IV collagenase mRNA expression decreased in the dermis after hydrocortisone treatment and that its expression correlated with that of p54c-ets-1. Taken together, these results indicate that hydrocortisone modulates c-ets-1 expression. In addition, they raise the interesting possibility that c-ets-1 might be involved in an altered pattern of feather development mediated by the accumulation of collagen due to a decrease in collagenase activities.

[Automatic computer analysis of fetal cardiac rhythm]. / Analyse automatique du rythme cardiaque foetal par ordinateur.

In utero cardiotocographic recording is currently one of the best means of diagnosis of fetal distress. The purpose of automatic tracing of the fetal heart rate is to prevent inter- and intra-individual variability in order to better evaluate the condition of the fetus. This study was carried out with the assistance of a cardiotocograph HP 8040A connected to a microcomputer equipped with a clock card. The heart signal may then be continuously recorded and stored on floppy disks, which are then reread and processed by microcomputer. The data are divided into time intervals (3, 5 or 10 seconds), selected by the physician. At each stage, mean, median and sample variation are calculated. Losses of signal are read. In a second stage, the use of a digital, linear and predictive filter (Kalman filter) applied to heart rates, allows baseline extraction as well as the detection of variations about this baseline (accelerations, decelerations). With the use of this filter on sample variations, it is possible to detect various variability periods, via two different approaches: classification of variability values in three groups: 0-5 bpm, 5-10 bpm, greater than 10 bpm, detection of increases or decreases of the variability as compared to the mean variability during the recording. Comparison of automatic analysis and visual analysis by segmentation is satisfactory in terms of variability. Detection of accelerations and decelerations is more problematic, for two reasons: the notion of baseline, the accuracy of digital detection: 15 bpm, 15 sec. All these problems are discussed.