Establishment of Rat Embryonic Stem Cells and Making of Chimera Rats

The rat is a reference animal model for physiological studies and for the analysis of multigenic human diseases such as hypertension, diabetes, neurological disorders, and cancer. The rats have long been used in extensive chemical carcinogenesis studies. Thus, the rat embryonic stem (rES) cell is an important resource for the study of disease models. Attempts to derive ES cells from various mammals, including the rat, have not succeeded. Here we have established two independent rES cells from Wister rat blastocysts that have undifferentiated characters such as Nanog and Oct3/4 genes expression and they have stage-specific embryonic antigen (SSEA) -1, -3, -4, and TRA-1-81 expression. The cells were successfully cultured in an undifferentiated state and can be possible over 18 passages with maintaining more than 40% of normal karyotype. Their pluripotent potential was confirmed by the differentiation into derivatives of the endoderm, mesoderm, and ectoderm. Most importantly, the rES cells are capable of producing chimera rats. Therefore, we established pluripotent rES cell lines that are widely used to produce genetically modified experimental rats for study of human diseases

The Liberation of Embryonic Stem Cells

Mouse embryonic stem (ES) cells are defined by their capacity to self-renew and their ability to differentiate into all adult tissues including the germ line. Along with efficient clonal propagation, these properties have made them an unparalleled tool for manipulation of the mouse genome. Traditionally, mouse ES (mES) cells have been isolated and cultured in complex, poorly defined conditions that only permit efficient derivation from the 129 mouse strain; genuine ES cells have not been isolated from another species in these conditions. Recently, use of small molecule inhibitors of glycogen synthase kinase 3 (Gsk3) and the Fgf-MAPK signaling cascade has permitted efficient derivation of ES cells from all tested mouse strains. Subsequently, the first verified ES cells were established from a non-mouse species, Rattus norvegicus. Here, we summarize the advances in our understanding of the signaling pathways regulating mES cell self-renewal that led to the first derivation of rat ES cells and highlight the new opportunities presented for transgenic modeling on diverse genetic backgrounds. We also comment on the implications of this work for our understanding of pluripotent stem cells across mammalian species

Trampoline related injuries in children: risk factors and radiographic findings

Background Backyard trampolines are immensely popular among children, but are associated with an increase of trampoline-related injuries. The aim of this study was to evaluate radiographs of children with trampoline related injuries and to determine the risk factors. Methods Between 2003 and 2009, 286 children under the age of 16 with backyard trampoline injuries were included in the study. The number of injuries increased from 13 patients in 2003 to 86 in 2009. The median age of the 286 patients was 7 years (range: 1–15 years). Totally 140 (49%) patients were males, and 146 (51%) females. Medical records and all available diagnostic imaging were reviewed. A questionnaire was sent to the parents to evaluate the circumstances of each injury, the type of trampoline, the protection equipment and the experience of the children using the trampoline. The study was approved by the Institutional Ethics Committee of the University Hospital of Bern. Results The questionnaires and radiographs of the 104 patients were available for evaluation. A fracture was sustained in 51 of the 104 patients. More than 75% of all patients sustaining injuries and in 90% of patients with fractures were jumping on the trampoline with other children at the time of the accident. The most common fractures were supracondylar humeral fractures (29%) and forearm fractures (25%). Fractures of the proximal tibia occurred especially in younger children between 2–5 years of age. Conclusions Children younger than 5 years old are at risk for specific proximal tibia fractures (“Trampoline Fracture”). A child jumping simultaneously with other children has a higher risk of suffering from a fracture