Urinary potassium excretion and its association with acute kidney injury in the intensive care unit

Purpose Using urinary indices as a quick bedside test to assist management of oliguria and acute kidney injury (AKI) has long been sought. This study assessed whether urinary potassium excretion is related to simultaneously calculated creatinine clearance (CrCl) and can predict AKI in the critically ill. Materials and methods In this prospective cohort study, the correlation between 2-h urinary potassium excretion and simultaneously calculated CrCl of 61 critically ill patients was assessed by Pearson's correlation coefficient, and their ability to predict AKI (≥stage 1 KDIGO) in the subsequent 7 days was assessed by area under the receiver-operating-characteristic (AUROC) curve. Results Urinary potassium excretion (median 6.2 mmol, range 0.8–24.3) correlated linearly with CrCl (correlation coefficient: 0.58, 95% confidence interval [CI] 0.38–0.72; p = 0.001), and had a moderate ability to predict subsequent AKI (n = 19 [31%]; AUROC 0.747, 95%CI 0.620–0.850; p = 0.001), especially in patients without prior exposure to furosemide within 24-h (correlation coefficient 0.61, 95%CI 0.41–0.76; AUROC 0.789, 95%CI 0.654–0.890; p = 0.001, respectively). Conclusions Urinary potassium excretion correlates with CrCl and predicts AKI in the critically ill without recent furosemide exposure. Given 2-hour urinary potassium excretion can be measured easily, its potential as a marker of renal function deserves further study

‘Coaching and Peer Assisted Learning’ (C‐PAL) ‐ the mental health nursing student experience: a qualitative evaluation

Introduction: This paper presents findings from a study that evaluated mental health nursing students’ experience of a team mentoring model called Coaching and Peer Assisted Learning (C-PAL). At present there are no published research studies into the effectiveness of team mentorship utilised by nursing students within inpatient mental health settings. Aim: The study utilised an interpretist methodology where the focus was on individuals in their social world. Method: Two focus groups were held with fifteen students who had experienced C-PAL in four in-patient wards. Findings: Students’ overall experience of piloting C-PAL was positive. Learning opportunities (Theme 3) appeared to be dependent on the quality of peer support (Theme 5) which in turn, enhanced the learner experience and increased the level of student confidence (Theme 6). Less positive experiences included inadequate preparation (Theme 1), poor understanding of the model and competition for learning experiences. Implications for practice: We tentatively suggest that team mentorship models such as C-PAL may be suitable for acute in-patient mental health settings. The success of C-PAL depends upon the preparation of nursing staff, mentors (Theme 4), coaches and students in relation to role expectations, shift rostering (Theme 2) and the implementation of ‘huddling’ to promote opportunistic learning

A holonomy characterisation of Fefferman spaces

We prove that Fefferman spaces, associated to non--degenerate CR structures of hypersurface type, are characterised, up to local conformal isometry, by the existence of a parallel orthogonal complex structure on the standard tractor bundle. This condition can be equivalently expressed in terms of conformal holonomy. Extracting from this picture the essential consequences at the level of tensor bundles yields an improved, conformally invariant analogue of Sparling's characterisation of Fefferman spaces.Comment: AMSLaTeX, 15 page

The Debye-Waller Factor in solid 3He and 4He

The Debye-Waller factor and the mean-squared displacement from lattice sites for solid 3He and 4He were calculated with Path Integral Monte Carlo at temperatures between 5 K and 35 K, and densities between 38 nm^(-3) and 67 nm^(-3). It was found that the mean-squared displacement exhibits finite-size scaling consistent with a crossover between the quantum and classical limits of N^(-2/3) and N^(-1/3), respectively. The temperature dependence appears to be T^3, different than expected from harmonic theory. An anisotropic k^4 term was also observed in the Debye-Waller factor, indicating the presence of non-Gaussian corrections to the density distribution around lattice sites. Our results, extrapolated to the thermodynamic limit, agree well with recent values from scattering experiments.Comment: 5 figure

Activation of neutrophils within pulmonary microvessels of rabbits exposed to cigarette smoke.

Previous studies have shown that polymorphonuclear leukocytes (PMN) are delayed in the pulmonary capillaries by the presence of cigarette smoke. To determine if the PMN delayed by smoking are activated, we estimated the in vivo expression of CD11/CD18 and L-selectin on the surface of PMN in lungs and peripheral blood of rabbits because these molecules are known to be upregulated and downregulated, respectively, on the surface of activated PMN. New Zealand white rabbits (3.5 +/- 0.1 kg) were exposed to either air (n = 5) or cigarette smoke (n = 5), and we used an established protocol to measure pulmonary vascular blood flow, volume, and red blood cell (RBC) transit time in the left lung. The right lungs were then fixed in 0.025% glutaraldehyde and stored in liquid nitrogen. Ultrathin sections were immuno-labeled with either the anti-CD18 monoclonal antibody 60.3 or the anti-L-selectin antibody Dreg-200, followed by a secondary antibody conjugated to 10 nm colloidal gold. The target antigens were quantified by counting the number of gold particles per micron (G/microns) of PMN surface membrane. The data show that smoke exposure had no effect on pulmonary blood flow, volume, or RBC transit time. However, it increased the expression of CD11/CD18 on intravascular PMN in the upper region of the lung (control, 7.4 +/- 1.3 G/microns; smoke-exposed, 13.2 +/- 3.3 G/microns; P < 0.05) and decreased the expression of L-selectin on intravascular PMN in both the lower (control, 5.5 +/- 2.0 G/microns; smoke-exposed, 2.6 +/- 1.5 G/microns; P = 0.05) and the upper (control, 6.8 +/- 1.4 G/microns; smoke-exposed, 2.6 +/- 1.2 G/microns; P < 0.05) regions

Genomic DNA transposition induced by human PGBD5

Transposons are mobile genetic elements that are found in nearly all organisms, including humans. Mobilization of DNA transposons by transposase enzymes can cause genomic rearrangements, but our knowledge of human genes derived from transposases is limited. In this study, we find that the protein encoded by human PGBD5, the most evolutionarily conserved transposable element-derived gene in vertebrates, can induce stereotypical cut-and-paste DNA transposition in human cells. Genomic integration activity of PGBD5 requires distinct aspartic acid residues in its transposase domain, and specific DNA sequences containing inverted terminal repeats with similarity to piggyBac transposons. DNA transposition catalyzed by PGBD5 in human cells occurs genome-wide, with precise transposon excision and preference for insertion at TTAA sites. The apparent conservation of DNA transposition activity by PGBD5 suggests that genomic remodeling contributes to its biological function

Structural and dielectric properties of Sr2_{2}TiO4_{4} from first principles

We have investigated the structural and dielectric properties of Sr$_{2}$TiO$_{4}$,the first member of the Sr$_{n+1}$Ti$_{n}$O$_{3n+1}$ Ruddlesden-Popper series, within density functional theory. Motivated by recent work in which thin films of Sr$_{2}$TiO$_{4}$ were grown by molecular beam epitaxy (MBE) on SrTiO$_{3}$ substrates, the in-plane lattice parameter was fixed to the theoretically optimized lattice constant of cubic SrTiO$_{3}$ (n=$\infty$), while the out-of-plane lattice parameter and the internal structural parameters were relaxed. The fully relaxed structure was also investigated. Density functional perturbation theory was used to calculate the zone-center phonon frequencies, Born effective charges, and the electronic dielectric permittivity tensor. A detailed study of the contribution of individual infrared-active modes to the static dielectric permittivity tensor was performed. The calculated Raman and infrared phonon frequencies were found to be in agreement with experiment where available. Comparisons of the calculated static dielectric permittivity with experiments on both ceramic powders and epitaxial thin films are discussed.Comment: 11 pages, 1 figure, 8 tables, submitted to Phys. Rev.

First-principles prediction of structure, energetics, formation enthalpy, elastic constants, polarization, and piezoelectric constants of AlN, GaN, and InN: comparison of local and gradient-corrected density-functional theory

A number of diverse bulk properties of the zincblende and wurtzite III-V nitrides AlN, GaN, and InN, are predicted from first principles within density functional theory using the plane-wave ultrasoft pseudopotential method, within both the LDA (local density) and GGA (generalized gradient) approximations to the exchange-correlation functional. Besides structure and cohesion, we study formation enthalpies (a key ingredient in predicting defect solubilities and surface stability), spontaneous polarizations and piezoelectric constants (central parameters for nanostructure modeling), and elastic constants. Our study bears out the relative merits of the two density functional approaches in describing diverse properties of the III-V nitrides (and of the parent species N$_2$, Al, Ga, and In), and leads us to conclude that the GGA approximation, associated with high-accuracy techniques such as multiprojector ultrasoft pseudopotentials or modern all-electron methods, is to be preferred in the study of III-V nitrides.Comment: RevTeX 6 pages, 12 tables, 0 figure

A promyelocytic leukemia protein-thrombospondin 2 axis and the risk of relapse in neuroblastoma

Purpose. Neuroblastoma is a childhood malignancy originating from the sympathetic nervous system with a complex biology, prone to metastasize and relapse. High-risk, metastatic cases are explained in part by amplification or mutation of oncogenes such as MYCN and ALK and loss of tumour suppressor genes in chromosome band 1p. However, it is fundamental to identify other pathways responsible for the large portion of neuroblastomas with no obvious molecular alterations. Experimental design. Neuroblastoma cell lines were used for assessment of tumour growth in vivo and in vitro. Protein expression in tissues and cells was assessed using immunofluorescence and immunohistochemistry. The association of PML expression with neuroblastoma outcome and relapse was calculated using log-rank and Mann-Whitney tests, respectively. Gene expression was assessed using chip microarrays. Results: PML is detected in the developing and adult sympathetic nervous system, whereas it is not expressed or low in metastatic neuroblastoma tumours. Reduced PML expression in patients with low-risk cancers - i.e. localized and negative for the MYCN protooncogene - is strongly associated with tumour recurrence. PML-I, but not PML-IV, isoform suppresses angiogenesis via upregulation of thrombospondin-2 (TSP-2), a key inhibitor of angiogenesis. Finally, PML-I and TSP-2 expression inversely correlates with tumour angiogenesis and recurrence in localized neuroblastomas. Dvorkina et al. A promyelocytic leukaemia protein-thrombospondin 2 axis and the risk of relapse in neuroblastoma 3 Conclusions: Our work reveals a novel PML-I-TSP2 axis for regulation of angiogenesis and cancer relapse, which could be used to identify patients with low-risk, localized tumours that might benefit from chemotherapy