Optimized surgical techniques and postoperative care improve survival rates and permit accurate telemetric recording in exercising mice

BACKGROUND: The laboratory mouse is commonly used as a sophisticated model in biomedical research. However, experiments requiring major surgery frequently lead to serious postoperative complications and death, particularly if genetically modified mice with anatomical and physiological abnormalities undergo extensive interventions such as transmitter implantation. Telemetric transmitters are used to study cardiovascular physiology and diseases. Telemetry yields reliable and accurate measurement of blood pressure in the free-roaming, unanaesthetized and unstressed mouse, but data recording is hampered substantially if measurements are made in an exercising mouse. Thus, we aimed to optimize transmitter implantation to improve telemetric signal recording in exercising mice as well as to establish a postoperative care regimen that promotes convalescence and survival of mice after major surgery in general. RESULTS: We report an optimized telemetric transmitter implantation technique (fixation of the transmitter body on the back of the mouse with stainless steel wires) for subsequent measurement of arterial blood pressure during maximal exercise on a treadmill. This technique was used on normal (wildtype) mice and on transgenic mice with anatomical and physiological abnormalities due to constitutive overexpression of recombinant human erythropoietin. To promote convalescence of the animals after surgery, we established a regimen for postoperative intensive care: pain treatment (flunixine 5 mg/kg bodyweight, subcutaneously, twice per day) and fluid therapy (600 mul, subcutaneously, twice per day) were administrated for 7 days. In addition, warmth and free access to high energy liquid in a drinking bottle were provided for 14 days following transmitter implantation. This regimen led to a substantial decrease in overall morbidity and mortality. The refined postoperative care and surgical technique were particularly successful in genetically modified mice with severely compromised physiological capacities. CONCLUSION: Recovery and survival rates of mice after major surgery were significantly improved by careful management of postoperative intensive care regimens including key supportive measures such as pain relief, administration of fluids, and warmth. Furthermore, fixation of the blood pressure transmitter provided constant reliable telemetric recordings in exercising mice

What is the optimal anesthetic protocol for measurements of cerebral autoregulation in spontaneously breathing mice?

Autoregulation, an important feature of the cerebral circulation, is affected in many diseases. Since genetically modified mice are a fundamental tool in biomedical research, including neuro(bio)logy also in this specie measurements of cerebral autoregulation (CA) are mandatory. However, this requires anesthesia that unfortunately significantly impacts cerebral perfusion and consequently might distort CA measurements directly or by altering arterial pCO2. The latter can be avoided by artificial ventilation but requires several control measurements of blood gases, each consuming at least 100μl of blood or 5% of a mouse's blood volume. To avoid such diagnostic hemorrhage, we systematically analyzed the effect of different common anesthetic protocols used for rodents in spontaneously breathing mice on CA measured with Laser speckle perfusion imaging. Halothane, Isoflurane and Pentobarbital abrogated CA and Ketamin/Xylazine as well as Chloralose had a moderate reproducibility. In contrast, the rather rarely used anesthetic Ethomidate applied in low doses combined with local anesthetics had the best reproducibility. Although with this anesthesia the lower CA limit was lower than with Ketamin/Xylazine and Chloralose as reported in the handful of papers so far dealing with CA in mice, we suggest Ethomidate as the anesthetic of choice for CA measurements in spontaneously breathing mic

Acute and chronic elevation of erythropoietin in the brain improves exercise performance in mice without inducing erythropoiesis

Application of recombinant human erythropoietin (rhEpo) improves exercise capacity by stimulating red blood cell production that, in turn, enhances oxygen delivery and utilization. Apart from this, when applied at high doses, rhEpo crosses the blood-brain barrier, triggering protective neuronal effects. Here we show a fundamental new role by which the presence of Epo in the brain augments exercise performance without altering red blood cell production. Two different animal models, the transgenic mouse line Tg21, which constitutively overexpresses human Epo exclusively in the brain without affecting erythropoiesis, and wild-type mice treated with a single high dose of rhEpo, demonstrate an unexpected improvement in maximal exercise performance independent of changes in total hemoglobin mass, as well as in whole blood volume and cardiovascular parameters. This novel finding builds a more complete understanding regarding the central effects of endogenously produced and exogenously applied Epo on exercise performance.-Schuler, B., Vogel, J., Grenacher, B., Jacobs, R. A., Arras, M., Gassmann, M. Acute and chronic elevation of erythropoietin in the brain improves exercise performance in mice without inducing erythropoiesis

Geographic variation in the cost of ambulatory care in Switzerland

OBJECTIVES: Swiss health care is relatively costly. In order better to understand the drivers of spending, this study analyses geographic variation in per capita consultation costs for ambulatory care. METHODS: Small area and longitudinal analysis of costs of ambulatory services covered by compulsory health insurance, 2003-07. RESULTS: The results show considerable geographic variation in per capita consultation costs, with higher costs in urban compared to rural areas. Areas with higher availability of care had higher costs, and residents of urban and high income areas used more specialist care and generated higher costs than residents of rural areas. CONCLUSIONS: There are persistent regional differences in the per capita cost of ambulatory care that are not explained by demographic factors, access to care, or needs. It is likely that higher access to care leads to greater inappropriate use, particularly of specialists. Implementing gatekeeping systems and financial incentives that encourage better coordination of primary care may slow growth in costs and improve care

Release of linker histone from the nucleosome driven by polyelectrolyte competition with a disordered protein

Highly charged intrinsically disordered proteins are essential regulators of chromatin structure and transcriptional activity. Here we identify a surprising mechanism of molecular competition that relies on the pronounced dynamical disorder present in these polyelectrolytes and their complexes. The highly positively charged human linker histone H1.0 (H1) binds to nucleosomes with ultrahigh affinity, implying residence times incompatible with efficient biological regulation. However, we show that the disordered regions of H1 retain their large-amplitude dynamics when bound to the nucleosome, which enables the highly negatively charged and disordered histone chaperone prothymosin α to efficiently invade the H1-nucleosome complex and displace H1 via a competitive substitution mechanism, vastly accelerating H1 dissociation. By integrating experiments and simulations, we establish a molecular model that rationalizes the remarkable kinetics of this process structurally and dynamically. Given the abundance of polyelectrolyte sequences in the nuclear proteome, this mechanism is likely to be widespread in cellular regulation

GPR15 facilitates recruitment of regulatory T cells to promote colorectal cancer.

Colorectal cancer (CRC) is one of the most frequent malignancies worldwide. Despite considerable progress in early detection and treatment, there is still an unmet need for novel anti-tumor therapies, particularly in advanced CRC. Regulatory T cells (Tregs) are increased in the peripheral blood and tumor tissue of CRC patients. Recently, transient ablation of tumor-associated Tregs was shown to foster CD8+ T cell-mediated anti-tumoral immunity in murine CRC models. However, before considering therapies, targeting Tregs in cancer patients and detailed knowledge of the phenotype and features of tumor-associated Tregs is indispensable. Here we demonstrate in a murine model of inflammation-induced CRC that tumor-associated Tregs are mainly of thymic origin and equipped with a specific set of molecules strongly associated with enhanced migratory properties. Particularly, a dense infiltration of Tregs in mouse and human CRC lesions correlated with increased expression of the orphan chemoattractant receptor GPR15 on these cells. Comprehensive gene expression analysis revealed that tumor-associated GPR15+ Tregs have a Th17-like phenotype, thereby producing IL-17 and TNF-α. Gpr15 deficiency repressed Treg infiltration in CRC, which paved the way for enhanced anti-tumoral CD8+ T cell immunity and reduced tumorigenesis. In conclusion, GPR15 represents a promising novel target for modifying T cell-mediated anti-tumoral immunity in CRC

Transplantation of a human liver following 3 days of ex situ normothermic preservation

Current organ preservation methods provide a narrow window (usually <12 hours) to assess, transport and implant donor grafts for human transplantation. Here we report the transplantation of a human liver discarded by all centers, which could be preserved for several days using ex situ normothermic machine perfusion. The transplanted liver exhibited normal function, with minimal reperfusion injury and the need for only a minimal immunosuppressive regimen. The patient rapidly recovered a normal quality of life without any signs of liver damage, such as rejection or injury to the bile ducts, according to a 1-year follow up. This inaugural clinical success opens new horizons in clinical research and promises an extended time window of up to 10 days for assessment of viability of donor organs as well as converting an urgent and highly demanding surgery into an elective procedure