Tests of a full-scale ITER toroidal interferometer and polarimeter (TIP) prototype on the DIII-D tokamak (invited)

A full-scale ITER toroidal interferometer and polarimeter (TIP) prototype, including an active feedback alignment system, has been installed and tested on the DIII-D tokamak. In the TIP prototype, a two-color interferometry measurement of line-integrated density is carried out at 10.59 μm and 5.22 μm using a CO₂ and quantum cascade laser, respectively, while a separate polarimetry measurement of the plasma-induced Faraday effect is made at 10.59 μm. The TIP prototype is equipped with a piezo tip/tilt stage active feedback alignment system that minimizes noise in the measurement and keeps the diagnostic aligned throughout DIII-D discharges. The measured phase resolution for the polarimeter and interferometer is 0.05° (100 Hz bandwidth) and 1.9° (1 kHz bandwidth), respectively. The corresponding line-integrated density resolution for the vibration-compensated interferometer is δnL = 1.5 × 10¹⁸ m^-2, and the magnetic field-weighted line-integrated density from the polarimeter is δnBL = 1.5 × 10¹⁹ Tm^-2. Both interferometer and polarimeter measurements during DIII-D discharges compare well with the expectations based on calculations using Thomson scattering measured density profiles and magnetic equilibrium reconstructions. Additionally, larger bandwidth interferometer measurements show that the diagnostic is a sensitive monitor of core density fluctuations with demonstrated measurements of Alfvén eigenmodes and tearing modes.

A heterodyne dispersion interferometer for wide bandwidth density measurements on DIII-D

In order to improve both the density and particularly the temporal resolution beyond previous dispersion interferometers (DIs), a heterodyne technique based on an acousto-optic (AO) cell has been added to the DI. A 40 MHz drive frequency for the AO cell allows density fluctuation measurements into the MHz range. A CO₂ laser-based heterodyne DI (HDI) installed on DIII-D has demonstrated that the HDI is capable of tracking the density evolution throughout DIII-D discharges, including disruption events and other rapid transient phenomena. The data also show good agreement with independent density measurements obtained with the existing DIII-D two-color interferometer. The HDI line-integrated density resolution sampled over a 1 s interval is ∼9 × 10¹⁷ m^-2. Density fluctuations induced by MHD instabilities are also successfully measured by the HDI.

A Type 1 Diabetes Genetic Risk Score Predicts Progression of Islet Autoimmunity and Development of Type 1 Diabetes in Individuals at Risk

OBJECTIVE

We tested the ability of a type 1 diabetes (T1D) genetic risk score (GRS) to predict progression of islet autoimmunity and T1D in at-risk individuals.

RESEARCH DESIGN AND METHODS

We studied the 1,244 TrialNet Pathway to Prevention study participants (T1D patients' relatives without diabetes and with one or more positive autoantibodies) who were genotyped with Illumina ImmunoChip (median [range] age at initial autoantibody determination 11.1 years [1.2-51.8], 48% male, 80.5% non-Hispanic white, median follow-up 5.4 years). Of 291 participants with a single positive autoantibody at screening, 157 converted to multiple autoantibody positivity and 55 developed diabetes. Of 953 participants with multiple positive autoantibodies at screening, 419 developed diabetes. We calculated the T1D GRS from 30 T1D-associated single nucleotide polymorphisms. We used multivariable Cox regression models, time-dependent receiver operating characteristic curves, and area under the curve (AUC) measures to evaluate prognostic utility of T1D GRS, age, sex, Diabetes Prevention Trial-Type 1 (DPT-1) Risk Score, positive autoantibody number or type, HLA DR3/DR4-DQ8 status, and race/ethnicity. We used recursive partitioning analyses to identify cut points in continuous variables.

RESULTS

Higher T1D GRS significantly increased the rate of progression to T1D adjusting for DPT-1 Risk Score, age, number of positive autoantibodies, sex, and ethnicity (hazard ratio [HR] 1.29 for a 0.05 increase, 95% CI 1.06-1.6; P = 0.011). Progression to T1D was best predicted by a combined model with GRS, number of positive autoantibodies, DPT-1 Risk Score, and age (7-year time-integrated AUC = 0.79, 5-year AUC = 0.73). Higher GRS was significantly associated with increased progression rate from single to multiple positive autoantibodies after adjusting for age, autoantibody type, ethnicity, and sex (HR 2.27 for GRS >0.295, 95% CI 1.47-3.51; P = 0.0002).

CONCLUSIONS

The T1D GRS independently predicts progression to T1D and improves prediction along T1D stages in autoantibody-positive relatives.

Influence of ions on two-dimensional and three-dimensional atomic force microscopy at fluorite-water interfaces

Recent advancement in liquid-environment atomic force microscopy (AFM) has enabled us to visualize three-dimensional (3D) hydration structures as well as two-dimensional (2D) surface structures with subnanometer-scale resolution at solid-water interfaces. However, the influence of ions present in solution on the 2D- and 3D-AFM measurements has not been well understood. In this study, we perform atomic-scale 2D- and 3D-AFM measurements at fluorite-water interfaces in pure water and a supersaturated solution of fluorite. The images obtained in these two environments are compared to understand the influence of the ions in solution on these measurements. In the 2D images, we found clear difference in the nanoscale structures but no significant difference in the atomic-scale contrasts. However, the 3D force images show clear difference in the subnanometer-scale contrasts. The force contrasts measured in pure water largely agree with those expected from the molecular dynamics simulation and the solvent tip approximation model. In the supersaturated solution, an additional force peak is observed over the negatively charged fluorine ion site. This location suggests that the observed force peak may originate from cations adsorbed on the fluorite surface. These results demonstrate that the ions can significantly alter the subnanometer-scale force contrasts in the 3D-AFM images.

A Cost-Effectiveness Analysis of Nintedanib in Idiopathic Pulmonary Fibrosis in the UK

BACKGROUND

International guidelines recommend nintedanib (OFEV^®) as an option for the treatment of idiopathic pulmonary fibrosis (IPF).

OBJECTIVE

The objective of this study was to assess the cost effectiveness of nintedanib versus pirfenidone, N-acetylcysteine and best supportive care (BSC) for the treatment of IPF from a UK payer's perspective.

METHODS

A Markov model was designed to capture the changes in the condition of adults with IPF. Efficacy outcomes included mortality, lung function decline and acute exacerbations. Treatment safety (serious adverse events) and tolerability (overall discontinuation) were also considered. The baseline risk of these events was derived from patient-level data from the placebo arms of nintedanib clinical trials (TOMORROW, INPULSIS-1, INPULSIS-2). A network meta-analysis (NMA) was conducted to estimate the relative effectiveness of the comparator treatments. Quality of life and healthcare resource use data from the clinical trials were also incorporated in the economic model.

RESULTS

Nintedanib showed statistically significant differences against placebo on acute exacerbation events avoided and lung function decline. In the cost-effectiveness analysis, the results were split between two treatments with relative low costs and modest effectiveness (BSC and N-acetylcysteine) and two that showed improved effectiveness (lung function) and higher costs (nintedanib and pirfenidone). All comparators were assumed to have similar projected survival and the difference in quality-adjusted life-years (QALYs) was driven by the acute exacerbations and lung function estimates. In the base-case deterministic pairwise comparison with pirfenidone, nintedanib was found to have fewer acute exacerbations and resulted in less costs and more QALYs gained.

CONCLUSIONS

Compared with BSC (placebo), nintedanib and pirfenidone were the only treatments to show statistical significance in the efficacy parameters. We found substantial uncertainty in the overall cost-effectiveness results between nintedanib and pirfenidone. N-Acetylcysteine was largely similar to BSC but with a worse survival profile. INPULSIS-1 and INPULSIS-2 ClinicalTrials.gov numbers, NCT01335464 and NCT01335477.

Bench testing of a heterodyne CO2 laser dispersion interferometer for high temporal resolution plasma density measurements

A heterodyne detection scheme is combined with a 10.59 μm CO₂ laser dispersion interferometer for the first time to allow large bandwidth measurements in the 10-100 MHz range. The approach employed utilizes a 40 MHz acousto-optic cell operating on the frequency doubled CO₂ beam which is obtained using a high 2nd harmonic conversion efficiency orientation patterned gallium arsenide crystal. The measured standard deviation of the line integrated electron density equivalent phase resolution obtained with digital phase demodulation technique, is 4 × 10¹⁷ m^-2. Air flow was found to significantly affect the baseline of the phase signal, which an optical table cover was able to reduce considerably. The heterodyne dispersion interferometer (DI) approach is found to be robustly insensitive to motion, with measured phase shifts below baseline drifts even in the presence of several centimeters of retroreflector induced path length variations. Plasma induced dispersion was simulated with a wedged ZnSe plate and the measured DI phase shifts are consistent with expectations.

Gamma ray imager on the DIII-D tokamak

A gamma ray camera is built for the DIII-D tokamak [J. Luxon, Nucl. Fusion 42, 614 (2002)] that provides spatial localization and energy resolution of gamma flux by combining a lead pinhole camera with custom-built detectors and optimized viewing geometry. This diagnostic system is installed on the outer midplane of the tokamak such that its 123 collimated sightlines extend across the tokamak radius while also covering most of the vertical extent of the plasma volume. A set of 30 bismuth germanate detectors can be secured in any of the available sightlines, allowing for customizable coverage in experiments with runaway electrons in the energy range of 1-60 MeV. Commissioning of the gamma ray imager includes the quantification of electromagnetic noise sources in the tokamak machine hall and a measurement of the energy spectrum of background gamma radiation. First measurements of gamma rays coming from the plasma provide a suitable testbed for implementing pulse height analysis that provides the energy of detected gamma photons.

PILOT EVALUATION OF A SIMPLE ADJUNCTIVE METHOD FOR IMPROVED REMOVAL OF ORAL BIOFILM DURING CONVENTIONAL SCALING AND ROOT PLANING THERAPY

Various studies have evaluated the adjunctive use of chemical and antimicrobial treatments to assist in the mechanical removal of oral microbial biofilm from tissue surfaces during scaling and root planning therapy (SRP). The current study demonstrates the elimination of two classes of surrogate molecular markers from periodontal disease sites. This suggests the current agent may be a more effective adjunctive cleansing agent for complete biofilm removal. A patient with advanced chronic periodontitis was subjected to standard SRP therapy, supplemented by irrigation with HYBENX® (HBX). Samples of gingival crevicular fluid were collected with triplicate absorbent paper points from each of three quadrants at three time points: 1) at baseline prior to treatment; 2) after irrigation with the topical agent for 20 seconds and rinsing; and 3) after SRP followed by a second irrigation/rinsing treatment with the agent. Paper points were extracted to assess the presence of 13 bacterial species known to be primarily associated with periodontal disease using DNA pyrosequencing. In addition, the presence of Matrix Metalloproteinase-8 (MMP8), as well as IL-1ß, IL-6, and TNF-alpha were also assessed by immunoassay of the paper point sample extracts. The combined adjunctive treatment indicated a complete absence of detectable bacterial DNA and the four inflammatory mediators from samples taken from the gingival sulci treated with HBX. The advantage of the current adjunctive topical treatment technique is that it is simple and easy to administer in conjunction with standard SRP techniques. It appears to provide a level of cleanliness not currently achieved with other SRP adjunctive procedures.

Molecular phylogeny and evolution of the cone snails (Gastropoda, Conoidea)

We present a large-scale molecular phylogeny that includes 320 of the 761 recognized valid species of the cone snails (Conus), one of the most diverse groups of marine molluscs, based on three mitochondrial genes (COI, 16S rDNA and 12S rDNA). This is the first phylogeny of the taxon to employ concatenated sequences of several genes, and it includes more than twice as many species as the last published molecular phylogeny of the entire group nearly a decade ago. Most of the numerous molecular phylogenies published during the last 15years are limited to rather small fractions of its species diversity. Bayesian and maximum likelihood analyses are mostly congruent and confirm the presence of three previously reported highly divergent lineages among cone snails, and one identified here using molecular data. About 85% of the species cluster in the single Large Major Clade; the others are divided between the Small Major Clade (∼12%), the Conus californicus lineage (one species), and a newly defined clade (∼3%). We also define several subclades within the Large and Small major clades, but most of their relationships remain poorly supported. To illustrate the usefulness of molecular phylogenies in addressing specific evolutionary questions, we analyse the evolution of the diet, the biogeography and the toxins of cone snails. All cone snails whose feeding biology is known inject venom into large prey animals and swallow them whole. Predation on polychaete worms is inferred as the ancestral state, and diet shifts to molluscs and fishes occurred rarely. The ancestor of cone snails probably originated from the Indo-Pacific; rather few colonisations of other biogeographic provinces have probably occurred. A new classification of the Conidae, based on the molecular phylogeny, is published in an accompanying paper.

Status and characterization of the lithium beam diagnostic on DIII-D

The 30 keV lithium beam diagnostic on DIII-D is suitable to measure both the radial electron density and poloidal magnetic field profiles in the pedestal. The refurbished system features a new setup to measure the Doppler shift allowing accurate alignment of the spectral filters. The injector has been optimized to generate a stable lithium neutral beam with a current of I = 15-20 mA and a diameter of 1.9 ± 0.1 cm measured by beam imaging. The typical temporal resolution is Δt = 1-10 ms and the radial resolution of ΔR = 5 mm is given by the optical setup. A new analysis technique based on fast Fourier transform avoids systematic error contributions from the digital lock-in analysis and accounts intrinsically for background light correction. Latest upgrades and a detailed characterization of the system are presented. Proof-of-principle measurements of the poloidal magnetic field with a statistical error of typically 2% show a fair agreement with the predictions modeled with the Grad-Shafranov equilibrium solver EFIT within 4%.

A systematic review of the evidence on service user involvement in interpersonal skills training of mental health students

Service user involvement has become a common feature of education programmes for mental health students. However, little is known about the effects of this type of education on the interpersonal skills of students taking part. This paper reports findings from a systematic review that formed part of a wider investigation into service user involvement in teaching interpersonal skills. The review aimed to locate and assess the quality of the published evidence relating to the effects of service user involvement on mental health students interpersonal skills and to synthesize results, using a definition of interpersonal skill that includes attitudes, empathy and skills as its key components. Results from this study indicate that the quality of evidence in this area is poor. However, sufficient synthesis of the evidence base was possible to allow conclusions and recommendations for both research and practice. Conclusions were that the involvement of service users in this area is both acceptable and valuable for students and had specific impacts on attitudes, empathy and skills. Some difficulties and reservations about the style of involvement are discussed. Recommendations for the conduct of future research are also made.

Embedded calibration system for the DIII-D Langmuir probe analog fiber optic links

This paper describes a generally applicable technique for simultaneously measuring offset and gain of 64 analog fiber optic data links used for the DIII-D fixed Langmuir probes by embedding a reference voltage waveform in the optical transmitted signal before every tokamak shot. The calibrated data channels allow calibration of the power supply control fiber optic links as well. The array of fiber optic links and the embedded calibration system described here makes possible the use of superior modern data acquisition electronics in the control room.

Initial results of the high resolution edge Thomson scattering upgrade at DIII-D

Validation of models of pedestal structure is an important part of predicting pedestal height and performance in future tokamaks. The Thomson scattering diagnostic at DIII-D has been upgraded in support of validating these models. Spatial and temporal resolution, as well as signal to noise ratio, have all been specifically enhanced in the pedestal region. This region is now diagnosed by 20 view-chords with a spacing of 6 mm and a scattering length of just under 5 mm sampled at a nominal rate of 250 Hz. When mapped to the outboard midplane, this corresponds to ~3 mm spacing. These measurements are being used to test critical gradient models, in which pedestal gradients increase in time until a threshold is reached. This paper will describe the specifications of the upgrade and present initial results of the system.

Large variation of vacancy formation energies in the surface of crystalline ice

Resolving the atomic structure of the surface of ice particles within clouds, over the temperature range encountered in the atmosphere and relevant to understanding heterogeneous catalysis on ice, remains an experimental challenge. By using first-principles calculations, we show that the surface of crystalline ice exhibits a remarkable variance in vacancy formation energies, akin to an amorphous material. We find vacancy formation energies as low as ~0.1-0.2 eV, which leads to a higher than expected vacancy concentration. Because a vacancy's reactivity correlates with its formation energy, ice particles may be more reactive than previously thought. We also show that vacancies significantly reduce the formation energy of neighbouring vacancies, thus facilitating pitting and contributing to pre-melting and quasi-liquid layer formation. These surface properties arise from proton disorder and the relaxation of geometric constraints, which suggests that other frustrated materials may possess unusual surface characteristics.

Chemical resolution at ionic crystal surfaces using dynamic atomic force microscopy with metallic tips

We demonstrate that well prepared and characterized Cr tips can provide atomic resolution on the bulk NaCl(001) surface with dynamic atomic force microscopy in the noncontact regime at relatively large tip-sample separations. At these conditions, the surface chemical structure can be resolved yet tip-surface instabilities are absent. Our calculations demonstrate that chemical identification is unambiguous, because the interaction is always largest above the anions. This conclusion is generally valid for other polar surfaces, and can thus provide a new practical route for straightforward interpretation of atomically resolved images.

Developing evidence-based process maps for spinal cord injury rehabilitation

STUDY DESIGN

Longitudinal audit.

OBJECTIVES

To develop evidence-based maps of rehabilitation for different lesion categories.

SETTING

Midlands, UK.

METHODS

Over a 5-year period data for all newly injured neurologically damaged patients aged 18 years or more were collected and analyzed (n=280). Data were collected from a functional independence measure (the Needs Assessment Checklist), patient records (paper and electronic) and patient goal planning records. The patients were grouped into different lesion categories. Standard milestones that patients in a given category would be expected to reach in rehabilitation were identified using goals set at goal planning meetings. Time when patients reached these milestones and variation between patients around time in reaching these milestones were calculated.

RESULTS

Median times from onset to admission, onset to rehabilitation and length of rehabilitation are given. Pictorial representations of rehabilitation (rehabilitation maps) were produced, using goals identified, median times of achievement and variation. This paper provides examples of these maps from one particular group, T8-T12 Frankel A.

CONCLUSION

Pathways of care can be used in a number of ways: to identify the need for service change; to audit service change; to provide evidence-based expectations for staff, patients and external parties; to look at variances affecting care; to make this service transparent; to provide figures for comparison with other philosophies of care; and to ensure consistency across the service.

Quantification of breast tissue index from MR data using fuzzy clustering

The study objective was to develop a segmentation technique to quantify breast tissue and total breast volume from magnetic resonance imaging (MRI) data to obtain a breast tissue index (BTI) related to breast density. Our goal is to quantify MR breast density to improve breast cancer risk assessment for certain high-risk populations for whom mammography is of limited usefulness due to high breast density. A semi-automatic 3D segmentation technique was implemented based on a fuzzy c-means technique (FCM) to segment fibroglandular tissue from fat in the breast images. After validation on a phantom, our FCM technique was first used to test the breast tissue measures reproducibility in two consecutive MR examinations of the same patients. The technique was then applied to measure the BTI on 10 high-risk patients. Results of BTI obtained with the semi-automated FCM method were compared with BTI results for the same patients using two other techniques, manual delineation and global threshold. BTI measures correlated well with mammographic densities (Pearson coefficients r = 0.78 using MR manual delineation, and r = 0.75 using MR FCM). The breast tissue index could therefore become a common measure for future studies of using noncontrast MRI data.

Controlled manipulation of atoms in insulating surfaces with the virtual atomic force microscope

We predict how single oxygen ions can be manipulated on the MgO (100) surface and demonstrate the possibility of detecting a single-atom event using a noncontact atomic force microscope. The manipulation process is simulated explicitly in real time with a virtual dynamic atomic force microscope including the full response of the instrumentation and demonstrates a strong dependence on temperature. The proposed new atomistic mechanism and protocols for the controlled manipulation of single atoms and vacancies on insulating surfaces may be relevant for anchoring molecules and metal clusters at these surfaces and controlling their electronic properties.

Reducing transfer times for coronary angiography in patients with acute coronary syndromes: one solution to a national problem

BACKGROUND

Patients with acute coronary syndrome (ACS) are at high risk of further cardiac events and benefit from early intervention, as reflected by international guidelines recommending early transfer to interventional centres. The current average waiting time of up to 21 days contravenes evidence based early intervention, creates geographical inequity of access, wastes bed days, and is unsatisfactory for patients.

METHODS

A regional transfer unit (RTU) was created to expatriate access of ACS patients referred from other centres to the revascularisation service. By redesigning the care pathway patients arriving on the RTU undergo angiography within 24 hours, and then leave the RTU the following day, allowing other ACS patients to be treated.

RESULTS

During the first six months of the RTU, the mean waiting time from referral to procedure decreased from 20 (SD 15) days (range 0-51) to 8 (SD 3) days (range 0-21) for 365 patients transferred from a district general hospital. Ninety seven per cent of patients underwent angiography within 24 hours, 61% having undergone percutaneous coronary intervention at the same sitting, and 78% were discharged home within 24 hours.

CONCLUSIONS

Delivering standards laid out in the National Service Framework, reducing inequalities of care across the region, and facilitating evidence based strategies of care represents a challenging and complex issue. For high risk patients suffering ACS who need early invasive investigation, a coordinated network wide approach together with the creation of an RTU resulted in a 62% reduction in waiting times for no extra resources. Further improvements can be expected through increased capacity of this verified strategy.

Analysis of mouse conceptuses with uniparental duplication/deficiency for distal chromosome 12: comparison with chromosome 12 uniparental disomy and implications for genomic imprinting

Distal mouse chromosome 12 is imprinted. Phenotypic analysis of mouse embryos with maternal or paternal uniparental disomy for the whole of chromosome 12 has characterized the developmental defects associated with the altered dosage of imprinted genes on this chromosome. Here we conduct a characterization of maternal and paternal Dp(dist12) mice using the reciprocal translocation T(4;12)47H. This limits the region analysed to the chromosomal domain distal to the T47H breakpoint in B3 on mouse chromosome 12. Both MatDp(dist12)T47H and PatDp(dist12)T47H conceptuses are non-viable and the frequency of recovery of Dp(dist12) conceptuses by 10.5 days post coitum (dpc) was lower than expected after normal adjacent-1 disjunction. A subset of MatDp(dist12) embryos can survive up to one day post partum. In contrast to paternal uniparental disomy 12 embryos, no live PatDp (dist12) embryos were recovered after 16.5 days of gestation. Other phenotypes observed in maternal and paternal chromosome 12 uniparental disomy mice are recapitulated in the Dp(dist12) mice and include placental, muscle and skeletal defects. Additional defects were also noted in the skin of both MatDp(dist12) and maternal uniparental disomy 12 embryos. This study shows that the developmental abnormalities associated with the altered parent of origin for mouse chromosome 12 can be attributed to the genomic region distal to the T47H breakpoint.

Venomous cone snails: molecular phylogeny and the generation of toxin diversity

In order to investigate the generation of conotoxin diversity, delta-conotoxin sequences from nine Conus species were analyzed in the context of their phylogeny. Using a standard molecular marker, mitochondrial 16S RNA, we determined that the delta-conotoxins were derived from three distinct species clades based on the phylogenetic reconstruction of a large set (>80) of Conus species and other toxoglossate molluscs. Four different mechanisms appear to have contributed to the diversity of the delta-conotoxins analyzed: (1) Speciation: Delta-conotoxins in different species diverge from each other (the prepro regions of orthologous genes somewhat more slowly than the reference rRNA rate, the mature toxin regions significantly faster). (2) Duplication: Intraspecific delta-conotoxin divergence is initiated by gene duplication events, some of which may have predated the species itself. (3) Recombination: A novel delta-conotoxin may arise through recombination of two parental delta-contoxin genes. (4) 'Focal hypermutation': This sudden, almost saltatory change in sequence is always restricted to the mature toxin region. The first three have been recognized previously as mechanisms important for the evolution of gene families in other phylogenetic systems; the last is a remarkable, mechanistically unexplained and specialized feature of Conus peptide diversification.

Delta-conotoxin structure/function through a cladistic analysis

Delta-conotoxins are Conus peptides that inhibit inactivation of voltage-gated sodium channels. The suggestion that delta-conotoxins might be an essential component of the venoms of fish-hunting cone snails which rapidly immobilize their prey [Terlau, H., Shon, K., Grilley, M., Stocker, M., Stühmer, W., and Olivera, B. M. (1996) Nature 381, 148-151] has not been tested. On the basis of cDNA cloning, all of the fish-hunting Conus analyzed yielded at least one delta-conotoxin sequence. In addition, one delta-conotoxin isolated from the venom of Conus striatus had an amino acid sequence identical to that predicted from cDNA cloning. This new peptide exhibited properties of delta-conotoxins: it targeted sodium channels and potentiated action potentials by slowing channel inactivation. Homologous sequences of delta-conotoxins from two groups (clades) of related fish-hunting Conus species share consensus features but differ significantly from the two known delta-conotoxins from mollusc-hunting Conus venoms. Three large hydrophobic amino acids were conserved; analogues of the previously described delta-conotoxin PVIA with alanine substituted for the conserved amino acids F9 and I12 lost substantial biological activity. In contrast, both the T8A and K13A delta-conotoxin PVIA analogues, where substitutions were at nonconserved loci, proved to be biologically active. Taken together, our results indicate that a cladistic approach can identify amino acids critical for the activity of conotoxins and provide extensive information as to which amino acid substitutions can be made without significant functional consequences.

Dynamic temporal and spatial regulation of the cdk inhibitor p57(kip2) during embryo morphogenesis

The complete developmental expression pattern of the cyclin dependent kinase inhibitor (CDKI) p57(kip2) has not been reported, here we report a detailed study of the localization of p57(kip2) protein during mouse organogenesis. We show that p57(kip2) is coincident with key stages of differentiation of several organs, some but not all of which are affected in Beckwith-Weidermann syndrome, a human congenital syndrome characterized by foetal overgrowth and childhood tumours.

Fungal trehalose phosphorylase: kinetic mechanism, pH-dependence of the reaction and some structural properties of the enzyme from Schizophyllum commune

Initial-velocity measurements for the phospholysis and synthesis of alpha,alpha-trehalose catalysed by trehalose phosphorylase from Schizophyllum commune and product and dead-end inhibitor studies show that this enzyme has an ordered Bi Bi kinetic mechanism, in which phosphate binds before alpha,alpha-trehalose, and alpha-D-glucose is released before alpha-D-glucose 1-phosphate. The free-energy profile for the enzymic reaction at physiological reactant concentrations displays its largest barriers for steps involved in reverse glucosyl transfer to D-glucose, and reveals the direction of phospholysis to be favoured thermodynamically. The pH dependence of kinetic parameters for all substrates and the dissociation constant of D-glucal, a competitive dead-end inhibitor against D-glucose (K(i)=0.3 mM at pH 6.6 and 30 degrees C), were determined. Maximum velocities and catalytic efficiencies for the forward and reverse reactions decrease at high and low pH, giving apparent pK values of 7.2--7.8 and 5.5--6.0 for two groups whose correct protonation state is required for catalysis. The pH dependences of k(cat)/K are interpreted in terms of monoanionic phosphate and alpha-D-glucose 1-phosphate being the substrates, and of the pK value seen at high pH corresponding to the phosphate group in solution or bound to the enzyme. The K(i) value for the inhibitor decreases outside the optimum pH range for catalysis, indicating that binding of D-glucal is tighter with incorrectly ionized forms of the complex between the enzyme and alpha-D-glucose 1-phosphate. Each molecule of trehalose phosphorylase contains one Mg(2+) that is non-dissociable in the presence of metal chelators. Measurements of the (26)Mg(2+)/(24)Mg(2+) ratio in the solvent and on the enzyme by using inductively coupled plasma MS show that exchange of metal ion between protein and solution does not occur at measurable rates. Tryptic peptide mass mapping reveals close structural similarity between trehalose phosphorylases from basidiomycete fungi.

Contryphans from Conus textile venom ducts

Contryphans are unusual Conus peptides which contain a distinctive post-translational modification, D-tryptophan or D-leucine. cDNA clones encoding new contryphans from the mollusc-hunting cone snail Conus textile were identified and the inferred mature peptides were synthesized: contryphan-Tx (Gly-Cys-Hyp-D-Trp-Gln-Pro-Tyr-Cys-NH(2)), Leu-contryphan-Tx (Cys-Val-D-Leu-Tyr-Pro-Trp-Cys-NH(2)) and contryphan R/Tx which is identical to contryphan-R [Jimenez et al., 1996. Contryphan is a D-tryptophan containing Conus peptide. J. Biol. Chem. 281, 28002-28005]. Leu-contryphan-Tx exhibits a single peak, but contryphan-Tx shows two peaks under reverse-phase high-performance liquid chromatography conditions. Ultraviolet resonance Raman spectroscopy demonstrates a difference in the D-tryptophan dihedral angle for the two contryphan-Tx equilibrium conformers. Both the sequences and in vivo effects of all contryphans isolated suggest that there are two major branches of the contryphan family.

Roles for genomic imprinting and the zygotic genome in placental development

The placenta contains several types of feto-maternal interfaces where zygote-derived cells interact with maternal cells or maternal blood for the promotion of fetal growth and viability. The genetic factors regulating the interactions between different cell types within feto-maternal interfaces and the relative contributions of the maternal and zygotic genomes are poorly understood. Genomic imprinting, the epigenetic process responsible for parental origin-dependent functional differences between homologous chromosomes, has been proposed to contribute to these events. Previous studies showed that mouse conceptuses with an absence of imprinted differences between the two copies of chromosome 12 (upon paternal inheritance of both copies) die late in gestation and have a variety of defects, including placentomegaly. Here we examined the role of chromosome 12 imprinting in these placentae in more detail. We show that the spatial interactions between different cell types within feto-maternal interfaces are defective and identify abnormal behaviors in both zygote-derived and maternal cells that are attributed to the genome of the zygote but not the mother. These include compromised invasion of the maternal decidualized endometrium and the central maternal artery situated within it by zygote-derived trophoblast, abnormalities in the wall of the central maternal artery, and defects within the zygote-derived cellular layer of the labyrinth, which is in direct contact with maternal blood. These findings demonstrate multiple roles for chromosome 12 imprinting in the placenta that have not previously been associated with imprinting effects. They provide insights into the function of imprinting in placental development and have evolutionary and clinical implications.

Parental origin-specific developmental defects in mice with uniparental disomy for chromosome 12

Genetic analysis has shown that the distal portion of mouse chromosome 12 is imprinted; however, the developmental roles of imprinted genes in this region are not known. We have therefore generated conceptuses with uniparental disomy for chromosome 12, in which both copies of chromosome 12 are either paternally or maternally derived (pUPD12 and mUPD12, respectively). Both types of UPD12 result in embryos that are non-viable and that exhibit distinct developmental abnormalities. Embryos with pUPD12 die late in gestation, whereas embryos with mUPD12 can survive to term but die perinatally. The mUPD12 conceptuses are invariably growth-retarded while pUPD12 conceptuses exhibit placentomegaly. Skeletal muscle maturation defects are evident in both types of UPD12. In addition, embryos with paternal UPD12 have costal cartilage defects and hypo-ossification of mesoderm-derived bones. In embryos with mUPD12, the development of the neural crest-derived middle ear ossicles is defective. Some of these anomalies are consistent with those seen with uniparental disomies of the orthologous chromosome 14 region in humans. Thus, imprinted genes on chromosome 12 are essential for viability, the regulation of prenatal growth, and the development of mesodermal and neural crest-derived lineages.

Evidence of genocide 7000 BP--Neolithic paradigm and geo-climatic reality

The early Neolithic fortified settlement of Schletz, Lower Austria is emerging as one of the most interesting sites of Linear Pottery culture excavation in Austria. In the course of systematic investigations carried out since 1983, a plethora of unexpected results have been obtained. Specifically, the human skeletal remains of 67 individuals have been found at the base of an oval trench system. Without exception, these remains are characterized by multiple traumatic lesions as well as carnivore gnaw marks. Demographic analysis presents the picture of the entire population of this early farming settlement having been extinguished. Further, the findings suggest that a genocide scenario may have been responsible for the final demise of this settlement. The age and sex distribution reveals a lack of young females, who are interpreted as having been abducted by aggressors. There is however no direct skeletal evidence of aggressors at the site; in fact, the uniformity of Strontium isotope ratios (HR-ICP-MS analysis) implies that all 67 individuals, who were left unburied for months, were indigenous. Supporting evidence of increased levels of inter-human aggression--possibly caused by a broad wave of migration--comes from other contemporary end linear pottery sites in Germany. Such findings are here discussed in the context of a dramatic geological event in the region of the Black Sea shelf at this time (7.550 BP), which led to the submergence of some 100.000 square kilometers of fertile land, and which might have been responsible for subsequent gradual population movements into the interior of Europe.

The successor's dilemma

Botched leadership transitions occur with alarming frequency--a fact that's laid bare regularly in the business pages of the nation's newspapers. The headlines trumpet the premature departures of designated successors--leaders such as Merrill Lynch's Herb M. Allison and AT&T's John Walter, who left their respective companies before they could claim the CEO's seat. Dan Ciampa and Michael Watkins, who have counseled senior executives and successors through more than 100 leadership transitions in the past 25 years, point to the successor's dilemma as the dominant cause of failed leadership transitions. The dilemma is an emotionally charged power struggle played out between the CEO and his would-be heir. Ciampa and Watkins describe the way the problem builds on both sides of the desk--the CEO's fear of giving up control versus the designated successor's need to enact the changes expected of him and prove himself to the board. They cite anecdotal evidence and their own research to suggest that this complex psychological dynamic leads CEO-successor relations astray and can block the successor's path to the top spot. But the authors also offer four ways for the would-be heir to overcome the successor's dilemma. These include gauging the CEO's readiness to leave before accepting the number two spot, maintaining regular communication with the CEO despite ever-present obstacles such as travel and business schedules, and developing and using a balanced personal advice network to help navigate the shift in power. The authors stress that defusing the problem is the responsibility of the successor, not the CEO. The reason is simple: the successor has the most to lose.

Trends in serum folate after food fortification

From 1994 to 1998, median serum folate values in clinical specimens increased from 12.6 to 18.7 microg/L. The percentage of low values decreased. Food fortification with folic acid is a likely explanation.

Speciation of cone snails and interspecific hyperdivergence of their venom peptides. Potential evolutionary significance of introns

All 500 species of cone snails (Conus) are venomous predators. From a biochemical/genetic perspective, differences among Conus species may be based on the 50-200 different peptides in the venom of each species. Venom is used for prey capture as well as for interactions with predators and competitors. The venom of every species has its own distinct complement of peptides. Some of the interspecific divergence observed in venom peptides can be explained by differential expression of venom peptide superfamilies in different species and of peptide superfamily branching in various Conus lineages into pharmacologic groups with different targeting specificity. However, the striking interspecific divergence of peptide sequences is the dominant factor in the differences observed between venoms. The small venom peptides (typically 10-35 amino acids in length) are processed from larger prepropeptide precursors (ca. 100 amino acids). If interspecific comparisons are made between homologous prepropeptides, the three different regions of a Conus peptide precursor (signal sequence, pro-region, mature peptide) are found to have diverged at remarkably different rates. Analysis of synonymous and nonsynonymous substitution rates for the different segments of a prepropeptide suggests that mutation frequency varies by over an order of magnitude across the segments, with the mature toxin region undergoing the highest rate. The three sections of the prepropeptide which exhibit apparently different mutation rates are separated by introns. This striking segment-specific rate of divergence of Conus prepropeptides suggests a role for introns in evolution: exons separated by introns have the potential to evolve very different mutation rates. Plausible mechanisms that could underlie differing mutational frequency in the different exons of a gene are discussed.

Contulakin-G, an O-glycosylated invertebrate neurotensin

We have purified contulakin-G, a 16-amino acid O-linked glycopeptide (pGlu-Ser-Glu-Glu-Gly-Gly-Ser-Asn-Ala-Thr-Lys-Lys-Pro-Tyr-Ile-Leu-OH, pGlu is pyroglutamate) from Conus geographus venom. The major glycosylated form of contulakin-G was found to incorporate the disaccharide beta-D-Galp-(1-->3)-alpha-D-GalpNAc-(1-->) attached to Thr10. The C-terminal sequence of contulakin-G shows a high degree of similarity to the neurotensin family of peptides. Synthetic peptide replicates of Gal(beta-->3) GalNAc(alpha-->)Thr10 contulakin-G and its nonglycosylated analog were prepared using an Fmoc (9-fluorenylmethoxycarbonyl) protected solid phase synthesis strategy. The synthetic glycosylated con- tulakin-G, when administered intracerebroventricular into mice, was found to result in motor control-associated dysfunction observed for the native peptide. Contulakín-G was found to be active at 10-fold lower doses than the nonglycosylated Thr10 contulakin-G analog. The binding affinities of contulakin-G and the nonglycosylated Thr10 contulakin-G for a number of neurotensin receptor types including the human neurotensin type 1 receptor (hNTR1), the rat neurotensin type 1 and type 2 receptors, and the mouse neurotensin type 3 receptor were determined. The binding affinity of the nonglycosylated Thr10 contulakin-G was approximately an order of magnitude lower than that of neurotensin1-13 for all the receptor types tested. In contrast, the glycosylated form of contulakin-G exhibited significantly weaker binding affinity for all of the receptors tested. However, both contulakin-G and nonglycosylated Thr10 contulakin-G were found to be potent agonists of rat neurotensin receptor type 1. Based on these results, we conclude that O-linked glycosylation appears to be a highly unusual strategy for increasing the efficacy of toxins directed against neurotransmitter receptors.

Low falls: an underappreciated mechanism of injury

OBJECTIVE

This is a retrospective study designed to evaluate the pattern and severity of injuries that result from low falls, defined as falls from less than 20 ft, subsequent mortality, and requirements of hospital resources. Our hypothesis is that many of these injuries, even without cardiopulmonary instability, are worthy of trauma center care.

METHODS

The records of all patients entered into the hospital trauma registry at an urban Level I trauma center during the years 1991 through 1997 who suffered low falls and who either died after admission or were hospitalized for at least 3 days were reviewed. Patients suffering isolated hip fractures were excluded. One hundred seventy-six patients constituted the study population. This group accounts for about 2% of all admissions for falls at our institution. Patterns of injury were examined. Age, mechanism of injury, Injury Severity Score (ISS), and cardiopulmonary or neurologic instability on admission were documented. Mortality, length of intensive care unit and hospital stays, as well as billed hospital charges, were reviewed.

RESULTS

The majority of patients (62%) were younger than 50 years. Sixty patients had ISS >15 and 116 patients had ISS >9. Sixty patients had multisystem injuries requiring specialty care. Head injuries were found in 81 patients (35%), and vertebral fractures or spinal cord injuries were found in 49 patients (22%), including 9 quadriplegics and 5 paraplegics. There were seven patients with intra-abdominal injuries (five spleen and two bowel injuries). There was one patient with a rupture of the thoracic aorta. Seventeen patients had deteriorating neurologic or pulmonary function on arrival, but the majority (90%) were stable. Of the 159 "stable" patients, 48 suffered head injuries, 7 were quadriplegic, and 3 were paraplegic. All intra-abdominal injuries were in this group. Overall, 14 of 176 patients (8%) died. Seven deaths were in patients older than 60 years, and seven deaths were in younger patients (p = 0.04). The majority of deaths (9 of 14) were from head trauma. Care in the intensive care unit was required in 92 of 176 patients. Nine patients had billed charges exceeding $100,000.

CONCLUSION

Low falls can cause significant injuries, most commonly to the head and spine. Based on mechanism of injury alone, patients injured in low falls might not be taken to trauma centers. We have found, however, that many of these patients sustain serious multisystem injuries, even though they are stable initially. Although these patients represent only a fraction of those who fall, our study would support adjustment of triage guidelines to recommend transport of such patients, particularly elderly patients, to trauma centers.

Are black nurses an endangered species?

In the late 1980s it was feared that black nurses in Britain were a dying species. There was a belief that young people of minority ethnic descent were being deterred from choosing nursing as a career owing to the discrimination, disadvantage and harassment experienced by their parents as health service workers. Anecdotal evidence and limited statistical evidence suggested that the number of black applicants to preregistration training in nursing and midwifery was lower than would be expected when compared with the representation of the minority ethnic groups in the population as a whole. Nevertheless, the evidential base has, to date, been limited. Using the most comprehensive data set available, this paper presents an analysis of the national pattern of applications from members of minority ethnic groups to preregistration nursing and midwifery training. The evidence indicates complex patterns of under- and, in some cases, over-representation of black and Asian minority ethnic groups.

mu-Conotoxin PIIIA, a new peptide for discriminating among tetrodotoxin-sensitive Na channel subtypes

We report the characterization of a new sodium channel blocker, mu-conotoxin PIIIA(mu-PIIIA). The peptide has been synthesized chemically and its disulfide bridging pattern determined. The structure of the new peptide is: [sequence: see text] where Z = pyroglutamate and O = 4-trans-hydroxyproline. We demonstrate that Arginine-14 (Arg14) is a key residue; substitution by alanine significantly decreases affinity and results in a toxin unable to block channel conductance completely. Thus, like all toxins that block at Site I, mu-PIIIA has a critical guanidinium group. This peptide is of exceptional interest because, unlike the previously characterized mu-conotoxin GIIIA (mu-GIIIA), it irreversibly blocks amphibian muscle Na channels, providing a useful tool for synaptic electrophysiology. Furthermore, the discovery of mu-PIIIA permits the resolution of tetrodotoxin-sensitive sodium channels into three categories: (1) sensitive to mu-PIIIA and mu-conotoxin GIIIA, (2) sensitive to mu-PIIIA but not to mu-GIIIA, and (3) resistant to mu-PIIIA and mu-GIIIA (examples in each category are skeletal muscle, rat brain Type II, and many mammalian CNS subtypes, respectively). Thus, mu-conotoxin PIIIA provides a key for further discriminating pharmacologically among different sodium channel subtypes.