Synthesis, Purification and Crystallization of Guanine-rich RNA Oligonucleotides

Guanine-rich RNA oligonucleotides display many novel structural motifs in recent crystal structures. Here we describe the procedures of the chemical synthesis and the purification of such RNA molecules that are suitable for X-ray crystallographic studies. Modifications of the previous purification methods allow us to obtain better yields in shorter time. We also provide 24 screening conditions that are very effective in crystallization of the guanine-rich RNA oligonucleotides. Optimal crystallization conditions are usually achieved by adjustment of the concentration of the metal ions and pH of the buffer. Crystals obtained by this method usually diffract to high resolution

Computer-based technology and student engagement: a critical review of the literature

Computer-based technology has infiltrated many aspects of life and industry, yet there is little understanding of how it can be used to promote student engagement, a concept receiving strong attention in higher education due to its association with a number of positive academic outcomes. The purpose of this article is to present a critical review of the literature from the past 5 years related to how web-conferencing software, blogs, wikis, social networking sites (Facebook and Twitter), and digital games influence student engagement. We prefaced the findings with a substantive overview of student engagement definitions and indicators, which revealed three types of engagement (behavioral, emotional, and cognitive) that informed how we classified articles. Our findings suggest that digital games provide the most far-reaching influence across different types of student engagement, followed by web-conferencing and Facebook. Findings regarding wikis, blogs, and Twitter are less conclusive and significantly limited in number of studies conducted within the past 5 years. Overall, the findings provide preliminary support that computer-based technology influences student engagement, however, additional research is needed to confirm and build on these findings. We conclude the article by providing a list of recommendations for practice, with the intent of increasing understanding of how computer-based technology may be purposefully implemented to achieve the greatest gains in student engagement. © 2017, The Author(s)

Autonomous weapons systems, killer robots and human dignity

One of the several reasons given in calls for the prohibition of autonomous weapons systems (AWS) is that they are against human dignity (Asaro in Int Rev Red Cross 94(886):687–709, 2012; Docherty in Shaking the foundations: the human rights implications of killer robots, Human Rights Watch, New York, 2014; Heyns in S Afr J Hum Rights 33(1):46–71, 2017; Ulgen in Human dignity in an age of autonomous weapons: are we in danger of losing an ‘elementary consideration of humanity’? 2016). However there have been criticisms of the reliance on human dignity in arguments against AWS (Birnbacher in Autonomous weapons systems: law, ethics, policy, Cambridge University Press, Cambridge, 2016; Pop in Autonomous weapons systems: a threat to human dignity? 2018; Saxton in (Un)dignified killer robots? The problem with the human dignity argument, 2016). This paper critically examines the relationship between human dignity and AWS. Three main types of objection to AWS are identified; (i) arguments based on technology and the ability of AWS to conform to international humanitarian law; (ii) deontological arguments based on the need for human judgement and meaningful human control, including arguments based on human dignity; (iii) consequentialist reasons about their effects on global stability and the likelihood of going to war. An account is provided of the claims made about human dignity and AWS, of the criticisms of these claims, and of the several meanings of ‘dignity’. It is concluded that although there are several ways in which AWS can be said to be against human dignity, they are not unique in this respect. There are other weapons, and other technologies, that also compromise human dignity. Given this, and the ambiguities inherent in the concept, it is wiser to draw on several types of objections in arguments against AWS, and not to rely exclusively on human dignity

New aspects in the pathogenesis, prevention, and treatment of hyponatremic encephalopathy in children

Hyponatremia is the most common electrolyte abnormality encountered in children. In the past decade, new advances have been made in understanding the pathogenesis of hyponatremic encephalopathy and in its prevention and treatment. Recent data have determined that hyponatremia is a more serious condition than previously believed. It is a major comorbidity factor for a variety of illnesses, and subtle neurological findings are common. It has now become apparent that the majority of hospital-acquired hyponatremia in children is iatrogenic and due in large part to the administration of hypotonic fluids to patients with elevated arginine vasopressin levels. Recent prospective studies have demonstrated that administration of 0.9% sodium chloride in maintenance fluids can prevent the development of hyponatremia. Risk factors, such as hypoxia and central nervous system (CNS) involvement, have been identified for the development of hyponatremic encephalopathy, which can lead to neurologic injury at mildly hyponatremic values. It has also become apparent that both children and adult patients are dying from symptomatic hyponatremia due to inadequate therapy. We have proposed the use of intermittent intravenous bolus therapy with 3% sodium chloride, 2 cc/kg with a maximum of 100 cc, to rapidly reverse CNS symptoms and at the same time avoid the possibility of overcorrection of hyponatremia. In this review, we discuss how to recognize patients at risk for inadvertent overcorrection of hyponatremia and what measures should taken to prevent this, including the judicious use of 1-desamino-8d-arginine vasopressin (dDAVP)

Preoperative assessment of the portal vein and hepatic artery in children with end-stage liver disease:Is selective angiography still necessary?

Background: Selective angiography involves increased risk for children and may cause vascular complications. The aim of this study was to determine whether selective angiography is still necessary for viewing the portal vein and hepatic artery. Methods: Doppler ultrasound, abdominal aortography, and selective angiography were performed and interpreted independently in 62 children (median age = 1 year 3 months), with end-stage liver disease, who were candidates for orthotopic liver transplantation. Results: Selective angiography agreed with the Doppler ultrasound findings of patency, flow direction, and diameter of the extrahepatic portal vein in 84%, 73%, and 79% of the children, respectively. Important additional information was obtained from selective angiography in only five of the 62 children (8%). Selective angiography showed an anomaly of the hepatic artery in 21 of the 62 children (33%). In 18 out of these 21 children (85%), an anomaly of the hepatic artery was already visible on the abdominal aortogram. Conclusion: Selective angiography did not play any significant role in the detection of an anomaly of the hepatic artery and should only be done if the Doppler ultrasound findings of the portal vein are inconclusive or if abdominal aortography cannot provide reliable information about the hepatic artery. For the evaluation of the portal vein and hepatic artery, we recommend Doppler ultrasound and abdominal aortography, a less invasive angiographic procedure