Development of Selective Pyrido[2,3-d]pyrimidin-7(8H)-one-Based Mammalian STE20-Like (MST3/4) Kinase Inhibitors.

Mammalian STE20-like (MST) kinases 1-4 play key roles in regulating the Hippo and autophagy pathways, and their dysregulation has been implicated in cancer development. In contrast to the well-studied MST1/2, the roles of MST3/4 are less clear, in part due to the lack of potent and selective inhibitors. Here, we re-evaluated literature compounds, and used structure-guided design to optimize the p21-activated kinase (PAK) inhibitor G-5555 (8) to selectively target MST3/4. These efforts resulted in the development of MR24 (24) and MR30 (27) with good kinome-wide selectivity and high cellular potency. The distinct cellular functions of closely related MST kinases can now be elucidated with subfamily-selective chemical tool compounds using a combination of the MST1/2 inhibitor PF-06447475 (2) and the two MST3/4 inhibitors developed. We found that MST3/4-selective inhibition caused a cell-cycle arrest in the G1 phase, whereas MST1/2 inhibition resulted in accumulation of cells in the G2/M phase.

Mosses modify effects of warmer and wetter conditions on tree seedlings at the alpine treeline.

Climate warming enables tree seedling establishment beyond the current alpine treeline, but to achieve this, seedlings have to establish within existing tundra vegetation. In tundra, mosses are a prominent feature, known to regulate soil temperature and moisture through their physical structure and associated water retention capacity. Moss presence and species identity might therefore modify the impact of increases in temperature and precipitation on tree seedling establishment at the arctic-alpine treeline. We followed Betula pubescens and Pinus sylvestris seedling survival and growth during three growing seasons in the field. Tree seedlings were transplanted along a natural precipitation gradient at the subarctic-alpine treeline in northern Sweden, into plots dominated by each of three common moss species and exposed to combinations of moss removal and experimental warming by open-top chambers (OTCs). Independent of climate, the presence of feather moss, but not Sphagnum, strongly supressed survival of both tree species. Positive effects of warming and precipitation on survival and growth of B. pubescens seedlings occurred in the absence of mosses and as expected, this was partly dependent on moss species. P. sylvestris survival was greatest at high precipitation, and this effect was more pronounced in Sphagnum than in feather moss plots irrespective of whether the mosses had been removed or not. Moss presence did not reduce the effects of OTCs on soil temperature. Mosses therefore modified seedling response to climate through other mechanisms, such as altered competition or nutrient availability. We conclude that both moss presence and species identity pose a strong control on seedling establishment at the alpine treeline, and that in some cases mosses weaken climate-change effects on seedling establishment. Changes in moss abundance and species composition therefore have the potential to hamper treeline expansion induced by climate warming.

Dwelling in the deep - strongly increased root growth and rooting depth enhance plant interactions with thawing permafrost soil.

Climate-warming-induced permafrost thaw exposes large amounts of carbon and nitrogen in soil at considerable depths, below the seasonally thawing active layer. The extent to which plant roots can reach and interact with these hitherto detached, deep carbon and nitrogen stores remains unknown. We aimed to quantify how permafrost thaw affects root dynamics across soil depths and plant functional types compared with above-ground abundance, and potential consequences for plant-soil interactions. A decade of experimental permafrost thaw strongly increased total root length and growth in the active layer, and deep roots invaded the newly thawed permafrost underneath. Root litter input to soil across all depths was 10 times greater with permafrost thaw. Root growth timing was unaffected by experimental permafrost thaw but peaked later in deeper soil, reflecting the seasonally receding thaw front. Deep-rooting species could sequester 15 N added at the base of the ambient active layer in October, which was after root growth had ceased. Deep soil organic matter that has long been locked up in permafrost is thus no longer detached from plant processes upon thaw. Whether via nutrient uptake, carbon storage, or rhizosphere priming, plant root interactions with thawing permafrost soils may feed back on our climate both positively and negatively.

Severe parvovirus B19 encephalitis after renal transplantation.

Human parvovirus B19 is a common cause of benign erythema infectiosum (fifth disease) in otherwise healthy children. Immunocompromized patients are at risk of developing chronic infections leading to chronic hyporegenerative anemia. We report the case of a nine-year-old boy who presented five days after renal transplantation with seizures and signs of encephalitis on MRI. The clinical course was characterized by anemia and seroconversion for parvovirus B19 accompanied by a high viral load (>10(9) copies per milliliter). A transfusion of red blood cells that the patient required after transplantation was found to be negative for parvovirus B19, leaving the donated organ as the most likely source of infection. Reduction of the immunosuppressive regimen led to complete recovery of the patient with a stable RBC count upon discharge. Parvovirus B19 infections should be considered in the differential diagnosis of seizures after solid organ transplantation.

In vitro validation and clinical testing of an indirect calorimetry system for ventilated preterm infants that is unaffected by endotracheal tube leaks and can be used during nasal continuous positive airway pressure.

Energy expenditure measurements in ventilated preterm infants are difficult because indirect calorimetry underestimates energy expenditure during gas leaks around uncuffed endotracheal tubes routinely used in preterm infants or during nasal continuous positive airway pressure (CPAP). We, therefore, developed a breath collector that simultaneously sampled expired air expelled at the ventilator outlet and escaping via the tube leak from the infant's mouth and nose. Our breath collector was combined with a proprietary calorimeter (Deltatrac II). In vitro validation was done by methanol burning (VO(2), 13.8 mL/min; VCO(2), 9.2 mL/min) during intermittent positive pressure ventilation (IPPV) with two commonly used ventilators (Sechrist IV-100B and Infant Star). Measurement error was determined at different ventilator flows, peak inspiratory pressures of 12-24 cm H(2)O, and during a complete tube leak. The mean measurement error with both ventilators was low (VO(2) +/- 3 %, VCO(2) +/- 2 %) even during a complete tube leak and did not increase with peak inspiratory pressure. The system response time was 2 min. In vivo measurements at the bedside were performed in 25 preterm infants (body weight, 537-1402 g). Energy expenditure during IPPV was 40 +/- 9 kcal/kg per day and 46 +/- 15 kcal/kg per day during nasal CPAP. The tube leak in the preterm infants studied during IPPV was 0 to 47 %, and during nasal CPAP 84 to 97 %. In conclusion, indirect calorimetry performed with our breath collector was accurate during IPPV and nasal CPAP and was unaffected by tube leaks.