Systemic recovery and therapeutic effects of transplanted allogenic and xenogenic mesenchymal stromal cells in a rat blunt chest trauma model

Background

Effective therapy of Acute Lung Injury (ALI) is still a major scientific and clinical problem. To define novel therapeutic strategies for sequelae of blunt chest trauma (TxT) like ALI/Acute Respiratory Distress Syndrome, we have investigated the immunomodulatory and regenerative effects of a single dose of ex vivo expanded human or rat mesenchymal stromal cells (hMSCs/rMSCs) with or without priming, immediately after the induction of TxT in Wistar rats.

EvoSketch: Simple simulations for learning random and probabilistic processes in evolution,and effects of instructional support on learners’ conceptual knowledge

Background

Students’ knowledge of scientific principles of evolution is often inadequate, despite its recognized importance for understanding biology. Moreover, difficulties associated with underlying abstract concepts such as randomness and probability can hinder successful learning of evolutionary concepts. Studies show that visualizations, particularly simulations together with appropriate instructional support, facilitate the learning of abstract concepts. Therefore, we have developed interactive, web-based simulation software called EvoSketch in efforts to help learners grasp the nature and importance of random and probabilistic processes in evolutionary contexts. We applied EvoSketch in an intervention study comparing four self-directed study conditions: learning with EvoSketch (1) alone, (2) combined with interpretative support, (3) combined with reflective support, and (4) using texts about randomness and probability instead of EvoSketch. All conditions received no support from any instructors. Knowledge about evolution as well as randomness and probability in the context of evolution, time-on-task, and perceived cognitive load were measured. A sample of 269 German secondary school students (M_age?=?15.6 years, SD?=?0.6 years) participated in the study.

Results

Learners using EvoSketch without additional support obtained higher follow-up test scores regarding their knowledge of randomness and probability than those using the text-based approach. However, use of the simulations together with given instructional support (interpretative or reflective) did not increase students’ performance, relative to the text-based approach. In addition, no significant between-intervention differences were found concerning the knowledge of evolution, while significant differences between the groups were detected concerning students’ perceived cognitive load and time-on-task.

Conclusions

From our findings, we conclude that EvoSketch seems to have a very small positive effect on students’ understanding of randomness and probability. Contrary to our expectations, additional self-directed instructional support did not improve students’ understanding, probably because it was not necessary to understand EvoSketch simulations. When using EvoSketch in the classroom, we recommend increasing the intervention timeframe to several sessions and a variety of evolutionary examples for which EvoSketch serves as an underlying framework.

     

Replication slippage may cause parallel evolution in the secondary structures of mitochondrial transfer RNAs

Presence of the dihydrouridine (D) stem in the mitochondrial cysteine tRNA is unusually variable among lepidosaurian reptiles. Phylogenetic and comparative analyses of cysteine tRNA gene sequences identify eight parallel losses of the D-stem, resulting in D-arm replacement loops. Sampling within the monophyletic Acrodonta provides no evidence for reversal. Slipped-strand mispairing of noncontiguous repeated sequences during replication or direct replication slippage can explain repeats observed within cysteine tRNAs that contain a D-arm replacement loop. These two mechanisms involving replication slippage can account for the loss of the cysteine tRNA D-stem in several lepidosaurian lineages, and may represent general mechanisms by which the secondary structures of mitochondrial tRNAs are altered.      

Fetal heart rate variability in growth restricted fetuses.

Intrauterine growth restriction (IUGR) remains a major problem in perinatal medicine because of the variety of its underlying causes and the prediction of its outcome. Characteristics of heartbeat interval patterns are associated with neuro-vegetative and humoral regulatory processes. Fetal magnetocardiography allows non-invasive assessment of these processes with high precision throughout the second half of gestation. The aim of our study was the analysis of linear and non-linear parameters of fetal heart rate fluctuations to distinguish between IUGR fetuses and a cohort of normal subjects, both pre-selected from heart-rate traces representing a quiet state of activity in the third trimester of gestation.