Comparison of the Fluid Resuscitation Rate with and without External Pressure Using Two Intraosseous Infusion Systems for Adult Emergencies,the CITRIN (Comparison of InTRaosseous infusion systems in emergency medicINe)-Study

Introduction

Intraosseous infusion is recommended if peripheral venous access fails for cardiopulmonary resuscitation or other medical emergencies. The aim of this study, using body donors, was to compare a semi-automatic (EZ-IO^®) device at two insertion sites and a sternal intraosseous infusion device (FASTR^™).

Methods

Twenty-seven medical students being inexperienced first-time users were randomized into three groups using EZ-IO and FASTR. The following data were evaluated: attempts required for successful placement, insertion time and flow rates with and without external pressure to the infusion.

Results

The first-pass insertion success of the EZ-IO tibia, EZ-IO humerus and FASTR was 91%, 77%, and 95%, respectively. Insertion times (MW±SD) did not show significant differences with 17±7 (EZ-IO tibia) vs. 29±42 (EZ-IO humerus) vs. 33±21 (FASTR), respectively. One-minute flow rates using external pressures between 0 mmHg and 300 mmHg ranged between 27±5 to 69±54 ml/min (EZ-IO tibia), 16±3 to 60±44 ml/min (EZ-IO humerus) and 53±2 to 112±47 ml/min (FASTR), respectively. Concerning pressure-related increases in flow rates, negligible correlations were found for the EZ-IO tibia in all time frames (c = 0.107–0.366; p≤0.013), moderate positive correlations were found for the EZ-IO humerus after 5 minutes (c = 0.489; p = 0.021) and strong positive correlations were found for the FASTR in all time frames (c = 0.63–0.80; p≤0.007). Post-hoc statistical power was 0.62 with the given sample size.

Conclusions

The experiments with first-time users applying EZ-IO and FASTR in body donors indicate that both devices may be effective intraosseous infusion devices, likely suitable for fluid resuscitation using a pressure bag. Variations in flow rate may limit their reliability. Larger sample sizes will prospectively be required to substantiate our findings.     

Effects of Initial Values and Convergence Criterion in the Two-Parameter Logistic Model When Estimating the Latent Distribution in BILOG-MG 3

Parameters of the two-parameter logistic model are generally estimated via the expectation-maximization algorithm, which improves initial values for all parameters iteratively until convergence is reached. Effects of initial values are rarely discussed in item response theory (IRT), but initial values were recently found to affect item parameters when estimating the latent distribution with full non-parametric maximum likelihood. However, this method is rarely used in practice. Hence, the present study investigated effects of initial values on item parameter bias and on recovery of item characteristic curves in BILOG-MG 3, a widely used IRT software package. Results showed notable effects of initial values on item parameters. For tighter convergence criteria, effects of initial values decreased, but item parameter bias increased, and the recovery of the latent distribution worsened. For practical application, it is advised to use the BILOG default convergence criterion with appropriate initial values when estimating the latent distribution from data.     

Tissue slice cultures from humans or rodents: a new tool to evaluate biological effects of heavy ions

The aim of this interdisciplinary project is to establish slice culture preparations from rodents and humans as a new model system for studying effects of X-rays and heavy ions within normal and tumor tissues. The advantage of such slice cultures relies on the conservation of an organotypic environment, the easy treatment and observation by live-imaging microscopy, and the independence from genetic immortalization strategies used to generate cell lines. Rat brains as well as human tumors were cut into 300-μm-thick sections and cultivated in an incubator in a humidified atmosphere at 37°C. This is realized by a membrane-based culture system with a liquid–air interface. With this system, it is possible to keep rodent slices viable for several months. Human brain tumor slices remained vital for at least 21 days. Slices were irradiated with X-rays at the radiation facility of the University Hospital in Frankfurt/Main at doses up to 40 Gy. Heavy ion irradiations were performed at GSI (Darmstadt) with different ions, energies, and doses. The irradiated slices were analyzed by 3D-confocal microscopy following immunostaining for DNA damage, microglia, and proliferation markers. The phosphorylated histone γH2AX proved to be suitable for the detection of ion traversals in this system.     

Misleading mollies: surface- but not cave-dwelling Poecilia mexicana males deceive competitors about mating preferences

Individuals providing misleading information to conspecifics may benefit from deception at the receiver's expense. A recent study (Plath et al., Curr Biol 18:1138–1141, 2008c) suggested that male Atlantic mollies (Poecilia mexicana) deceive rival males about their preferred mate. Here, we contrasted potentially deceptive behavior in surface-dwelling P. mexicana males to males of the cave form of that species (the cave molly). Unlike many other cavefishes, cave mollies have retained functional eyes and readily respond to visual stimuli. Males could interact freely with two females (large and small), and an audience male was visually presented during the second part of the tests. When observed during mate choice, males reduced their mating activity, but this reduction was significantly weaker in cave mollies. Overall, the expression of mating preferences (determined through frequencies of nipping and thrusting) declined in front of an audience; again, this effect was significantly weaker in the cave form. Reduced sexual activity and reduced expression of mating preferences can be interpreted as an attempt of the focal male to avoid unintended interception of information by the rival male. Surface but not cave molly males directed their first sexual interaction (when being observed by the rival male) towards the initially non-preferred female, suggesting that surface-dwelling males deceive rival males about their mating preferences. Deception by the focal males may be an adaptation to avoid sperm competition, since other males in their social environment may use public information and copy the focal male's mate choice. It seems that sending deceptive signals is evolutionarily regressed in the cave molly, since mate choice copying is unlikely to occur under naturally dark conditions, and also the potential to deceive rivals about mating preferences is probably very limited.     

Iron-mediated oxidative stress plays an essential role in ferritin-induced cell death

Previously, we have demonstrated an apoptosis-inducing activity of an acidic, H-chain-rich isoferritin secreted from primary rat hepatocytes in vitro. Because this proapoptotic property may be responsible for the growth-inhibitory and immunosuppressive effects described for certain ferritin species, we aimed to address the mechanism by which ferritin can trigger cell death. Suggesting a pivotal role for iron, iron chelation by desferrioxamine significantly abrogates ferritin-mediated apoptosis and necrosis in primary rat hepatocytes and substantially lowers the extent of protein modification by 4-hydroxynonenal (HNE)—a major lipid peroxidation (LPO) product. Furthermore, supplementing the cultures with the radical-scavenging compound trolox also provided significant protection from ferritin-mediated apoptosis. Moreover, a significant increase in micronucleated cells upon exposure to ferritin indicates that ferritin also introduces damage to DNA. Based on these observations we therefore propose that endocytosis of extracellular ferritin increases the level of free ferrous iron in the lysosomal compartment, promoting Fenton chemistry-based oxidative stress involving LPO and increased lysosomal membrane permeability. Subsequently, the release of reactive lysosomal content leads to cellular damage, in particular modification of protein and DNA induced by HNE and other reactive aldehydic LPO products. Together, these effects will trigger apoptosis and necrosis based on the upregulation of p53, increased mitochondrial membrane permeability, and proapoptotic Fas signaling as described recently. In conclusion, based on their iron-storing ability, secreted acidic isoferritins may act as soluble mediators of oxidative stress under certain physiological and pathophysiological conditions.     

The importance of forest patch networks for the conservation of the Thorn-tailed Rayaditos in central Chile

Conservation of forest birds in fragmented landscapes requires not only determining the critical patch characteristics influencing local population persistence but also identifying patch networks providing connectivity and suitable habitat conditions necessary to ensure regional persistence. In this study, we assessed the importance of patch attributes, patch connectivity, and network components (i.e., groups of interconnected patches) in explaining the occupancy pattern of the Thorn-tailed Rayadito (Aphrastura spinicauda), a forest bird species of central Chile. Using a daily movement threshold distance, we identified a total of 16 network components of sclerophyllous forest within the study area. Among those components, patch area and vegetation structure-composition were important predictors of patch occupancy. However, the inclusion of patch connectivity and component size (i.e., the area of a network component) into the models greatly increases the models’ accuracy and parsimony. Using the best-fitted model, a total of 33 patches were predicted to be occupied by rayaditos within the study area, but such occupied patches were distributed in only six network components. These results suggest that persistence of rayaditos in central Chile requires the maintenance of large single patches and patch networks providing habitat and connectivity.