Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics.

Uranium and plutonium's 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (e.g., the six different allotropes of elemental plutonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization for which a quantitative measure is lacking. By employing resonant X-ray emission spectroscopy (RXES) and X-ray absorption near-edge structure (XANES) spectroscopy and making comparisons to specific heat measurements, we demonstrate the presence of multiconfigurational f-orbital states in the actinide elements U and Pu and in a wide range of uranium and plutonium intermetallic compounds. These results provide a robust experimental basis for a new framework toward understanding the strongly-correlated behavior of actinide materials.

X-ray diffraction at the National Ignition Facility.

We report details of an experimental platform implemented at the National Ignition Facility to obtain in situ powder diffraction data from solids dynamically compressed to extreme pressures. Thin samples are sandwiched between tamper layers and ramp compressed using a gradual increase in the drive-laser irradiance. Pressure history in the sample is determined using high-precision velocimetry measurements. Up to two independently timed pulses of x rays are produced at or near the time of peak pressure by laser illumination of thin metal foils. The quasi-monochromatic x-ray pulses have a mean wavelength selectable between 0.6 Å and 1.9 Å depending on the foil material. The diffracted signal is recorded on image plates with a typical 2θ x-ray scattering angle uncertainty of about 0.2° and resolution of about 1°. Analytic expressions are reported for systematic corrections to 2θ due to finite pinhole size and sample offset. A new variant of a nonlinear background subtraction algorithm is described, which has been used to observe diffraction lines at signal-to-background ratios as low as a few percent. Variations in system response over the detector area are compensated in order to obtain accurate line intensities; this system response calculation includes a new analytic approximation for image-plate sensitivity as a function of photon energy and incident angle. This experimental platform has been used up to 2 TPa (20 Mbar) to determine the crystal structure, measure the density, and evaluate the strain-induced texturing of a variety of compressed samples spanning periods 2-7 on the periodic table.

Proteomic profiling of rectal cancer reveals acid ceramidase is implicated in radiation response.

BACKGROUND: Neoadjuvant chemoradiotherapy (CRT) is used in locally advanced rectal cancer when tumours threaten the circumferential resection margin, with varying response to treatment. This experimental study aimed to identify significantly differentially expressed proteins between patients responding and not responding to CRT, and to validate any proteins of interest. METHODS: Mass spectrometry (with isobaric tagging for relative quantification) analysis of rectal cancers pre- and post-CRT, and at resection. Validation of proteins of interest was performed by assessing tissue microarray (TMA) immunohistochemistry expression in a further 111 patients with rectal cancer. RESULTS: Proteomic data are available via ProteomeXchange with identifier PXD008436. Reduced abundance of contributing peptide ions for acid ceramidase (AC) (log fold change -1.526, p = 1.17E-02) was observed in CRT responders. Differential expression of AC was confirmed upon analysis of the TMAs. Cancer site expression of AC in stromal cells from post-CRT resection specimens was observed to be relatively low in pathological complete response (p = 0.003), and relatively high with no response to CRT (p = 0.017). CONCLUSION: AC may be implicated in the response of rectal cancer to CRT. We propose its further assessment as a novel potential biomarker and therapeutic target. SIGNIFICANCE: There is a need for biomarkers to guide the use of chemoradiotherapy in rectal cancer, as none are in routine clinical use. We have determined acid ceramidase may have a role in radiation response, based on novel proteomic profiling and validation in a wider dataset using tissue microarrays. The ability to predict or improve response would positively select those patients who will derive benefit, prevent delays in the local and systemic management of disease in non-responders, and reduce morbidity associated with chemoradiotherapy.

Probing the population of the spin-orbit split levels in the actinide 5f states.

Spin-orbit interaction in the 5f states is believed to strongly influence exotic behaviors observed in actinide metals and compounds. Understanding these interactions and how they relate to the actinide series is of considerable importance. To address this issue, the branching ratio of the white-line peaks of the N4,5 edge for the light actinide metals, alpha-Th, alpha-U, and alpha-Pu were recorded using electron energy-loss spectroscopy (EELS) in a transmission electron microscope (TEM) and synchrotron-radiation-based X-ray absorption spectroscopy (XAS). Using the spin-orbit sum rule and the branching ratios from both experimental spectra and many-electron atomic spectral calculations, accurate values of the spin-orbit interaction, and thus the relative occupation of the j = 5/2 and 7/2 levels, are determined for the actinide 5f states. Results show that the spin-orbit sum rule works very well with both EELS and XAS spectra, needing little or no correction. This is important, since the high spatial resolution of a TEM can be used to overcome the problems of single-crystal growth often encountered with actinide metals, allowing acquisition of EELS spectra, and subsequent spin-orbit analysis, from nm-sized regions. The relative occupation numbers obtained by our method have been compared with recent theoretical results and they show a good agreement in their trend.

Structural basis of activity and subunit recognition in G protein heterotrimers.

BACKGROUND: Inactive heterotrimeric G proteins are composed of a GDP-bound alpha subunit (Galpha) and a stable heterodimer of Gbeta and Ggamma subunits. Upon stimulation by a receptor, Galpha subunits exchange GDP for GTP and dissociate from Gbetagamma, both Galpha and Gbetagamma then interact with downstream effectors. Isoforms of Galpha, Gbeta and Ggamma potentially give rise to many heterotrimeric combinations, limited in part by amino acid sequence differences that lead to selective interactions. The mechanism by which GTP promotes Gbetagamma dissociation is incompletely understood. The Gly203-->Ala mutant of Gialpha1 binds and hydrolyzes GTP normally but does not dissociate from Gbetagamma, demonstrating that GTP binding and activation can be uncoupled. Structural data are therefore important for understanding activation and subunit recognition in G protein heterotrimers. RESULTS: The structures of the native (Gialpha1beta1gamma2) heterotrimer and that formed with Gly203-->AlaGialpha1 have been determined to resolutions of 2.3 A and 2.4 A, respectively, and reveal previously unobserved segments at the Ggamma2 C terminus. The Gly203-->Ala mutation alters the conformation of the N terminus of the switch II region (Val201-Ala203), but not the global structure of the heterotrimer. The N termini of Gbeta and Ggamma form a rigid coiled coil that packs at varying angles against the beta propeller of Gbeta. Conformational differences in the CD loop of beta blade 2 of Gbeta mediate isoform-specific contacts with Galpha. CONCLUSIONS: The Gly203-->Ala mutation in Gialpha1 blocks the conformational changes in switch II that are required to release Gbetagamma upon binding GTP. The interface between the ras-like domain of Galpha and the beta propeller of Gbeta appears to be conserved in all G protein heterotrimers. Sequence variation at the Gbeta-Galpha interface between the N-terminal helix of Galpha and the CD loop of beta blade 2 of Gbeta1 (residues 127-135) could mediate isoform-specific contacts. The specificity of Gbeta and Ggamma interactions is largely determined by sequence variation in the contact region between helix 2 of Ggamma and the surface of Gbeta.

Lung function in adolescents receiving high-dose methotrexate.

Methotrexate (MTX) has been implicated as a cause of interstitial pneumonitis and/or fibrosis, but the mechanism by which the drug causes these processes is not known. The purpose of this study was to determine whether patients receiving high-dose MTX developed a consistent decrease in pulmonary function, which would implicate a role for total dose of MTX received in the pathogenesis of the lung toxicity. Pulmonary function studies, including spirometry, plethysmography, and diffusing capacity at two levels of alveolar PO2, were performed in 38 adolescents treated for osteogenic sarcoma. The patients were divided into three groups including 12 patients (group 1) studied before and during therapy, 15 patients (group 2) studied during therapy, and 11 patients (group 3) studied after completion of treatment. While total dose received at the time of the study varied from 0 to 256 gm/sq m, pulmonary function showed no change, with one exception. A mild restrictive defect and decrease in diffusing capacity due to unilateral pleural and diaphragmatic disease, whose relationship to MTX therapy is uncertain, developed in one patient. MTX, when administered in high dose to young patients by the described protocol, causes no dose-related decrease in pulmonary function.

Pediatric office-based smoking intervention: impact on maternal smoking and relapse.

OBJECTIVE: To determine the impact of a brief smoking intervention delivered by pediatricians in the context of usual well baby office visits on postnatal maternal smoking and relapse. SETTING: Forty-nine private pediatric practices including 128 practitioners. DESIGN: Randomization of pediatric practices into minimal and extended intervention sites with all enrolled mothers of newborns within a practice receiving the same level of intervention. INTERVENTION: Smoking mothers in minimal condition received a hospital packet containing written information about passive smoking and a letter advising them to quit. Those in extended condition received the hospital packet plus oral and written advice at usual well baby visits: 2 weeks, 2, 4, and 6 months. MEASUREMENTS: Smoking and relapse rates at 6 months postpartum, demographics associated with smoking status, attitudes, and knowledge in regard to passive smoking, and recall surveys of mothers in regard to receiving advice or written materials. RESULTS: Two-thousand nine-hundred-one mothers of newborns were enrolled in the study. Those in the extended condition had higher quit rates (5.9% vs 2.7%, P < .01) and lower relapse rates (45% vs 55%, P < .01) than those in the minimal condition. Mothers' educational status and the presence of a smoking partner in the home were the major demographic variables associated with smoking status at enrollment and at follow-up. Compared with smokers in the minimal condition, those in extended at 6 months postpartum had significantly better attitudes and knowledge regarding passive smoking and allowed less smoking in the home. Mothers attending extended practices reported much higher rates of receiving oral advice and written materials than those in the minimal condition. CONCLUSIONS: A brief program can lead to major increases in the willingness of pediatricians to deliver smoking advice. A 1- to 2-minute intervention delivered in the context of usual well baby care can have a positive impact on maternal smoking and especially upon relapse prevention. A recent smoking history should be obtained from all mothers of newborns so that interventions can be aimed at both cessation and relapse prevention.

Specimen preparation of free-standing, thick-metal, multilayered films in cross section.

A new preparation method permits the production of large-area, electron-transparent, transmission electron microscopy (TEM) specimens in cross section of free-standing, thick, multilayered structures. Such production often has been difficult in the past because of large chemical differences between the component layers in the multilayer. This difference usually results in a large difference in thinning rates between the layers. A unique combination of electroplating, lapping, dimpling, and low-angle ion milling is a successful and reproducible technique for producing high-quality TEM specimens of these complex materials. Procedures and results presented here are for a 304 stainless-steel/copper multilayer having a repeat period of 20 nm and a total thickness of 20 microns.

An in situ nanoindentation specimen holder for a high voltage transmission electron microscope.

We describe in detail, the design, construction, and testing of a specimen holder that allows for the nanoindentation of surfaces while viewing in cross-section in a high voltage transmission electron microscope (TEM). This nanoindentation specimen holder, having three-axis position control of a diamond indenter in combination with micromachined specimens, allows for the first time the dynamic observation of subsurface microstructure evolution under an indenter tip. Additionally, the sample design techniques that have been developed for these procedures may eliminate the need for TEM specimen preparation for additional ex situ nanoindentation experiments. Initial experimental results from in situ indentation of Si samples in the high voltage electron microscope are reported here to demonstrate the capability of this new specimen holder.

Preparation of multilayered materials in cross-section for in situ TEM tensile deformation studies.

The success of in situ transmission electron microscopy experimentation is often dictated by proper specimen preparation and sample design procedures. We have developed a novel technique permitting the production of tensile specimens of multilayered films in cross-section for in situ deformation studies. Of primary, importance in the development of this technique is the production of an electron transparent micro-gauge section. This micro-gauge section predetermines the position at which plastic deformation, crack nucleation and growth, and failure are observed. In short, we report in detail, a unique combination of specimen preparation procedural steps and the design of a multilayer foil sample. The ability of these procedures to facilitate the success of in situ TEM tensile studies of layered materials in cross-section is demonstrated using a Cu-Zr multilayer foil.

Moment analysis of multibreath nitrogen washout in young children.

The purpose of this study was to determine whether on-line computerized moment analysis of multibreath N2 washout (MBNW) could be used as a method of estimating lung function in children too young to cooperate with routine pulmonary function testing. The limits of normal variability were determined from results obtained from duplicate studies performed on 36 healthy children ages 3-6 yr. Five healthy adults were studied for comparison. Test sensitivity was estimated by comparing the results in the healthy group to those of 10 age-matched children with cystic fibrosis (CF). Outcome variables of interest included functional residual capacity, the first-to-zeroth moment ratio (M1/M0), the second-to-zeroth moment ratio (M2/M0), and the lung clearance index. Test precision in the healthy group was high with the intrasubject coefficient of variation for all variables being less than 10%. There was no difference in mean within- or among-subject variability between the healthy children and the older, theoretically more cooperative, healthy adults. Mean M1/M0 and M2/M0 were both higher in CF than in the healthy group, 2.69 vs. 2.32 and 13.04 vs. 9.31, respectively (P less than 0.001). Moment ratios in CF showed good negative correlations with Shwachman scores; thus those CF patients with the most advanced lung disease had the highest moment ratios and vice versa. Moment analysis of MBNW has promise as a means of quantifying lung function in young children, since the method is noninvasive, low in inherent variability, requires only quiet breathing, and has the sensitivity required to detect rather mild ventilation inhomogeneity.

Respiratory impedance and multibreath N2 washout in healthy, asthmatic, and cystic fibrosis subjects.

We measured forced expiratory volume in 1 s (FEV1), respiratory impedance (Zrs) from 4 to 60 Hz, and a multibreath N2 washout (MBNW) in 6 normal, 10 asthmatic, and 5 cystic fibrosis (CF) subjects. The MBNW were characterized by the mean dilution number (MDN) derived by a moment analysis. The Zrs spectra were characterized by the minimum resistance (Rmin), the drop in resistance (Rdrop) from 4 Hz to Rmin, and the first resonance frequency (Fr1). Measurements were repeated after bronchodilation in three normal and all asthmatic subjects. Before bronchodilation, six of the asthmatic subjects showed close to normal FEV1. The Zrs in the normal subjects showed low Rmin (1.9 +/- 0.7 cmH2O.l-1.s), Rdrop (0.4 +/- 0.4), and Fr1 (10 +/- 2 Hz). Four of the mildly obstructed asthmatic subjects had normal Zrs but elevated MDNs (i.e., abnormal ventilation distribution). The other six asthmatic subjects had significantly elevated Rmin (4.1 +/- 0.8), Rdrop (6.3 +/- 5.8), and Fr1 (34 +/- 0.4 Hz) and elevated MDNs. The CF patients had elevated Zrs features and MDNs. After bronchodilation, no changes in FEV1, MDN, or Zrs occurred in the normal subjects. All asthmatic subjects showed increased FEV1 and decreased MDN, but the Zrs was unaltered in the four asthmatic subjects whose base-line Zrs was normal. For the other six asthmatic subjects, there were large decreases in the Rmin, Rdrop, and Fr1. Finally, there was a poor correlation between the MDN and the Zrs features but high correlation between the Zrs features alone. These results imply that significant nonuniform peripheral airway obstruction can exist such that ventilation distribution is abnormal but Zrs from 4 to 60 Hz is not. Abnormalities in Zrs from 4 to 60 Hz occur only after significant overall obstruction in the peripheral and more central airways. Combining Zrs and the MBNW may permit us to infer whether the disease is predominantly in the lung periphery or in the more central airways.

Pulmonary function testing in children.

This article concentrates on those factors that are particularly important for performing and interpreting lung function tests in children. Specifically, technical considerations such as equipment, personnel, test performance, and bronchoprovocation procedures are discussed. Changes in lung function with growth and appropriate use of race-specific reference standards are emphasized, and references for standard and experimental pulmonary function tests are provided. Several examples illustrating the utility of pulmonary function testing in clinical situations in children with lung disease are provided as well.

The "worth" of routine spirometry in a cystic fibrosis clinic.

In our cystic fibrosis clinic, all patients older than 6 years perform spirometry at each visit just before being seen by the health care team. Upon review, we determined that our perceived rationale for this practice was that the medical history fails to detect deterioration in a sizable minority of patients whose pulmonary decline can be detected by spirometry. Furthermore, the literature and our own experience indicates that physical examination frequently will not detect changes in pulmonary status until the changes are advanced. As part of an ongoing quality/cost assessment, we decided to challenge our rationale for performing routine spirometry. Using standard methodology, we developed a six-item Likert style questionnaire, the purpose of which was to assess perceived changes in pulmonary symptoms since the last clinic visit. The questionnaire had an acceptable degree of internal consistency (Cronbach's alpha = 0.92), although the question about sputum production showed the least correlation with responses to other items. We administered the questionnaire to 103 consecutive different patients and examined the association between reported changes in symptoms and actual changes in spirometric outcomes. Overall, there was a statistically significant, but clinically weak association between symptom scores and change in FEV1, r2 = 0.16, P < 0.001. Twenty-three patients had a decline in FEV1 of > or = 10% from one clinic visit to the next. Depending on the method used to place symptom scores into categories indicating that pulmonary symptoms were "worse," "same," or "better" than at the last clinic visit, 40-60% of these 23 patients indicated they felt the "same" or "better." We conclude that spirometry is a justifiable part of all clinic visits for patients with cystic fibrosis, assuming that one would want to detect and treat declines in pulmonary status before they become advanced.

A high-resolution serial sectioning specimen preparation technique for application to electron backscatter diffraction.

A high-resolution serial sectioning specimen preparation technique is described for acquisition of electron backscatter diffraction (EBSD) data. The primary objective is to develop a method to reproducibly remove a controlled thickness of material from a polycrystalline Ta sample while producing quality surfaces for EBSD orientation imaging. This is integrated with the ability to accurately measure the amount of material removed with each iteration and experimentally register the ensuing EBSD scans. To facilitate enhanced accuracy of this method, a metrology device containing high-precision etching patterns is fabricated using standard lithographic techniques. This metrology device allows for the sub-micron measurement of the serial section slice thickness and approximately 1 microm registration accuracy of each EBSD scan.

Office pulmonary function testing.

The underutilization of pulmonary function tests is due to many factors, including a general misunderstanding of the physiology involved and confusion over who to test, when and how to test them, and what equipment to use. This article attempts to demystify pulmonary function tests and makes practical suggestions concerning equipment and techniques to be used, discussing those tests that can easily be performed in an office setting: spirometry and peak flow rate.

Expression of basic fibroblast growth factor in nasal polyps.

Basic fibroblast growth factor (bFGF) is a polypeptide that is mitogenic for a wide variety of cell types. We used Northern blot analysis and immunohistochemistry to determine if bFGF is expressed in the nasal polyp tissue; bFGF messenger RNA was detectable in the polyps examined by Northern blot analysis. Strong immunostaining for bFGF was found in blood vessels and along the basement membrane of the epithelial cell layers. Basal epithelial cells and some infiltrating mononuclear cells also stained for bFGF. Proliferating cell nuclear antigen colocalized with bFGF to basal epithelial cells, endothelial cells, and areas of focal epithelial metaplasia. The polyp tissue was double-labeled with a mouse monoclonal antitryptase, a specific mast cell marker, and anti-bFGF. A significant number (65% +/- 19%) of the bFGF-positive mononuclear cells in the polyp tissues were positive for tryptase. These findings suggest that bFGF may contribute to the endothelial and epithelial proliferation in nasal polyp tissues and that mast cells are one source of this growth factor.

Implementation of "Open Airways" as an educational intervention for children with asthma in an HMO.

This article describes the adaptation and implementation of an existing pediatric asthma-management educational program, Open Airways, for members of a large group practice health maintenance organization. Seventy-four children ages 4 to 14 years and their families were randomized into one of seven class cohorts as part of a larger study of pediatric asthma management. The Open Airways program was modified to increase the emphasis on behavioral change and medication information and to reflect the different sociodemographic makeup of the population, compared with that for which the program was developed. Of the 74 families, 62 attended at least one class, and 47 of these attended five or more classes. Evaluations after classes suggest an increase in parental confidence in managing their child's asthma and an earlier use of medications. Health care providers may be able to adapt similar programs for successful use with their populations.

A Gaussian method to improve work-of-breathing calculations.

The work of breathing is a calculated index of pulmonary function in ventilated patients that may be useful in deciding when to wean and when to extubate. However, the accuracy of the calculated work of breathing of the patient (WOBp) can suffer from artifacts introduced by coughing, swallowing, and other non-breathing maneuvers. The WOBp in this case will include not only the usual work of inspiration, but also the work of performing these non-breathing maneuvers. The authors developed a method to objectively eliminate the calculated work of these movements from the work of breathing, based on fitting to a Gaussian curve the variable P, which is obtained from the difference between the esophageal pressure change and the airway pressure change during each breath. In spontaneously breathing adults the normal breaths fit the Gaussian curve, while breaths that contain non-breathing maneuvers do not. In this Gaussian breath-elimination method (GM), breaths that are two standard deviations from that mean obtained by the fit are eliminated. For normally breathing control adult subjects, GM had little effect on WOBp, reducing it from 0.49 to 0.47 J/L (n = 8), while there was a 40% reduction in the coefficient of variation. Non-breathing maneuvers were simulated by coughing, which increased WOBp to 0.88 (n = 6); with the GM correction, WOBp was 0.50 J/L, a value not significantly different from that of normal breathing. Occlusion also increased WOBp to 0.60 J/L, but GM-corrected WOBp was 0.51 J/L, a normal value. As predicted, doubling the respiratory rate did not change the WOBp before or after the GM correction.(ABSTRACT TRUNCATED AT 250 WORDS)

Variability, reproducibility, and data-collection time of pulmonary bedside monitoring.

Breath-by-breath pulmonary function testing at the bedside is now available both with special-purpose stand-alone equipment and with the new generation of ventilators. The authors studied the variability of, reproducibility of, and ideal length of data collection for nine indices of pulmonary function that may be useful for ventilatory management, weaning, and patient comfort. Work of breathing (as both J/L and J/min), pressure-time product, rapid shallow breathing index, respiratory time fraction, respiratory drive, change in esophageal pressure during inspiration, expiratory airway resistance, and dynamic compliance were measured in ten normal subjects and in eight patients being weaned from mechanical ventilation. All nine indices were reproducible when compared by paired t-test with two separate sets of data collected in normal subjects. Repeated measures in the normal subjects allowed calculation of 95% confidence intervals for the nine variables. There was no statistically significant difference between data collections of 5 minutes compared with those of 10 and 15 minutes. Breath-by-breath variability ranged from a coefficient of variation of 3% for the shallow breathing index in one patient to 131% for the work of breathing in J/min in another. Population variability ranged from values reported previously for other pulmonary parameters to nearly double for some parameters. The authors conclude that a 5-minute data collection time is sufficient to obtain reliable breath-by-breath data at the bedside. While taken together these indices may provide clinically useful information, their usefulness individually remains to be demonstrated because of their large variability.