Short-term renal support in postoperative repair of tetralogy of Fallot in the paediatric intensive care unit: can we predict those who need it?

INTRODUCTION: Fluid balance and renal function can be difficult to manage in the postoperative infant with tetralogy of Fallot. High fluid volumes are often needed to maintain cardiac output. Aims To stratify patients at risk for advanced renal support following tetralogy of Fallot repair. METHODS: Retrospective analysis of all consecutive tetralogy of Fallot cases operated at a single centre in a 3-year period. RESULTS: A total of 41 children were identified. All cases had loop diuretics administered. Of the cases, 17% required support with a peritoneal dialysis catheter, with only one complication of peritoneal dialysis catheter blockage. The mean length of paediatric intensive care unit stay in those receiving peritoneal dialysis catheter insertion was prolonged by an additional mean of 6 days (p<0.001). No statistical significance was found between those children requiring peritoneal dialysis and those who did not when considering patient age and weight at time of repair, cardiopulmonary bypass and aortic cross clamp times, the presence of a transannular patch, or junctional ectopic tachycardia. However, volume requirement of more than 35 ml/kg in the first 12 hours following repair did increase the likelihood to need peritoneal dialysis (p<0.0001). Furthermore, the higher the peak creatinine, the longer the stay on intensive care (p<0.01). CONCLUSIONS: Peritoneal dialysis is an effective method of dealing with fluid balance in children after tetralogy of Fallot repair, with minimal complications. Early consideration should be given to peritoneal dialysis when it is clear that high fluid volumes are required postoperatively.

Genome size expansion and the relationship between nuclear DNA content and spore size in the Asplenium monanthes fern complex (Aspleniaceae).

BACKGROUND: Homosporous ferns are distinctive amongst the land plant lineages for their high chromosome numbers and enigmatic genomes. Genome size measurements are an under exploited tool in homosporous ferns and show great potential to provide an overview of the mechanisms that define genome evolution in these ferns. The aim of this study is to investigate the evolution of genome size and the relationship between genome size and spore size within the apomictic Asplenium monanthes fern complex and related lineages. RESULTS: Comparative analyses to test for a relationship between spore size and genome size show that they are not correlated. The data do however provide evidence for marked genome size variation between species in this group. These results indicate that Asplenium monanthes has undergone a two-fold expansion in genome size. CONCLUSIONS: Our findings challenge the widely held assumption that spore size can be used to infer ploidy levels within apomictic fern complexes. We argue that the observed genome size variation is likely to have arisen via increases in both chromosome number due to polyploidy and chromosome size due to amplification of repetitive DNA (e.g. transposable elements, especially retrotransposons). However, to date the latter has not been considered to be an important process of genome evolution within homosporous ferns. We infer that genome evolution, at least in some homosporous fern lineages, is a more dynamic process than existing studies would suggest.

Biologically-inspired soft exosuit.

In this paper, we present the design and evaluation of a novel soft cable-driven exosuit that can apply forces to the body to assist walking. Unlike traditional exoskeletons which contain rigid framing elements, the soft exosuit is worn like clothing, yet can generate moments at the ankle and hip with magnitudes of 18% and 30% of those naturally generated by the body during walking, respectively. Our design uses geared motors to pull on Bowden cables connected to the suit near the ankle. The suit has the advantages over a traditional exoskeleton in that the wearer's joints are unconstrained by external rigid structures, and the worn part of the suit is extremely light, which minimizes the suit's unintentional interference with the body's natural biomechanics. However, a soft suit presents challenges related to actuation force transfer and control, since the body is compliant and cannot support large pressures comfortably. We discuss the design of the suit and actuation system, including principles by which soft suits can transfer force to the body effectively and the biological inspiration for the design. For a soft exosuit, an important design parameter is the combined effective stiffness of the suit and its interface to the wearer. We characterize the exosuit's effective stiffness, and present preliminary results from it generating assistive torques to a subject during walking. We envision such an exosuit having broad applicability for assisting healthy individuals as well as those with muscle weakness.

Apomixis and reticulate evolution in the Asplenium monanthes fern complex.

BACKGROUND AND AIMS: Asexual reproduction is a prominent evolutionary process within land plant lineages and especially in ferns. Up to 10 % of the approx. 10 000 fern species are assumed to be obligate asexuals. In the Asplenium monanthes species complex, previous studies identified two triploid, apomictic species. The purpose of this study was to elucidate the phylogenetic relationships in the A. monanthes complex and to investigate the occurrence and evolution of apomixis within this group. METHODS: DNA sequences of three plastid markers and one nuclear single copy gene were used for phylogenetic analyses. Reproductive modes were assessed by examining gametophytic and sporophyte development, while polyploidy was inferred from spore measurements. KEY RESULTS: Asplenium monanthes and A. resiliens are confirmed to be apomictic. Asplenium palmeri, A. hallbergii and specimens that are morphologically similar to A. heterochroum are also found to be apomictic. Apomixis is confined to two main clades of taxa related to A. monanthes and A. resiliens, respectively, and is associated with reticulate evolution. Two apomictic A. monanthes lineages, and two putative diploid sexual progenitor species are identified in the A. monanthes clade. CONCLUSIONS: Multiple origins of apomixis are inferred, in both alloploid and autoploid forms, within the A. resiliens and A. monanthes clades.

Tripodal imidazole frameworks: Reversible vapour sorption both with and without significant structural changes.

A series of tripodal imidazole frameworks (TIFs) are reported based on a tripodal, cavity-containing tris(imidazole) derivative. In the case of [Co(3)Cl(6)(1)(2)]·n(solvent) (TIF-1) which possesses a doubly interpenetrated framework structure, the material exhibits rigid, permanent porosity and selectively absorbs CO(2). The non-interpenetrated [Co(1)(2)(H(2)O)(2)]Cl(2)·4H(2)O (TIF-2) also absorbs gases and vapours fully reversibly exhibiting a reversible phase change in the process and considerable conditioning and hysteresis. The very highly hydrated [Co(1)(2)]Cl(2)·22H(2)O (TIF-3) irreversibly dehydrates to the layered structure [Co(1)(2)]Cl(2)·H(2)O (TIF-4). A nickel analogue [Ni(1)(2)]Cl(2)·22H(2)O (TIF-5) closely related to TIF-3 is also reported along with two isostructural, non-porous materials [MCl(2)(1)] (M = Mn, TIF-6; M = Cd, TIF-7) based on d(5) and d(10) Mn(II) and Cd(II). Some of the materials may be prepared by mechanochemical as well as solution based methods. We liken TIF-1 to a gas cylinder, TIF-2 to a sponge and TIF-3 to a fragile soda can that is crushed on emptying to give TIF-4.