Polycomb contraction differentially regulates terminal human hematopoietic differentiation programs.

BACKGROUND: Lifelong production of the many types of mature blood cells from less differentiated progenitors is a hierarchically ordered process that spans multiple cell divisions. The nature and timing of the molecular events required to integrate the environmental signals, transcription factor activity, epigenetic modifications, and changes in gene expression involved are thus complex and still poorly understood. To address this gap, we generated comprehensive reference epigenomes of 8 phenotypically defined subsets of normal human cord blood. RESULTS: We describe a striking contraction of H3K27me3 density in differentiated myelo-erythroid cells that resembles a punctate pattern previously ascribed to pluripotent embryonic stem cells. Phenotypically distinct progenitor cell types display a nearly identical repressive H3K27me3 signature characterized by large organized chromatin K27-modification domains that are retained by mature lymphoid cells but lost in terminally differentiated monocytes and erythroblasts. We demonstrate that inhibition of polycomb group members predicted to control large organized chromatin K27-modification domains influences lymphoid and myeloid fate decisions of primary neonatal hematopoietic progenitors in vitro. We further show that a majority of active enhancers appear in early progenitors, a subset of which are DNA hypermethylated and become hypomethylated and induced during terminal differentiation. CONCLUSION: Primitive human hematopoietic cells display a unique repressive H3K27me3 signature that is retained by mature lymphoid cells but is lost in monocytes and erythroblasts. Intervention data implicate that control of this chromatin state change is a requisite part of the process whereby normal human hematopoietic progenitor cells make lymphoid and myeloid fate decisions.

An online tests catalog for clinical laboratories.

An attempt to integrate an online catalog for clinical laboratory tests in a university hospital medical computing environment is presented here. The need for such a catalog is evident, due to the dynamic changes in the area, new tests, and new test methods. Physicians are able to access the catalog through department terminals. The catalog has been designed and implemented as a relational database, including seven tables. Context-sensitive help screens are available at any step, as well as specific instructions for each laboratory.

Rates of sickness absenteeism among employees of a modern hospital: the role of demographic and occupational factors.

Sickness absenteeism, of hospital employees particularly, is a problem of concern due to its negative economic and morale impacts. The aim of the first stage of the study was to identify according to some demographic (sex, age, marital status) and occupational (occupational group, duration of hospital employment) variables those groups of hospital employees who are at higher risk of sickness absenteeism. A comparison with the data of the study performed in the same hospital about 15 years ago showed a rise in the duration of absences with a simultaneous reduction in their incidence. Sickness absenteeism was higher among female, mainly unskilled, workers, presently or previously married, aged from 45 to 60, and employed in the hospital for over ten years. Continuous social and medical surveillance of these employees is suggested as a promising way of reducing sickness absenteeism.