The effect of body weight on intravenous diltiazem in patients with atrial fibrillation with rapid ventricular response.

WHAT IS KNOWN AND OBJECTIVES: To assess the effect of body weight on the total dose of intravenous (IV) diltiazem needed to reach goal heart rate (HR) for atrial fibrillation (Afib) with rapid ventricular response (RVR) in the emergency department (ED) setting. METHODS: A single-center retrospective cohort was ascertained using electronic medical record data from January 2013 to December 2016. Inclusion criteria consisted of new onset Afib with RVR, receipt of IV diltiazem in the ED, and age ≥18 years old. The primary outcome was the total dose of diltiazem needed to reach goal HR <100, stratified by patients who were <100 kg and those ≥100 kg. The secondary outcome was the total time required to reach goal HR. Demographic, clinical and medication-related data were collected, including selected safety endpoints. RESULTS AND DISCUSSION: A total of 328 patients were included. Patients required a mean of 30.1 mg (±24.6) of diltiazem and 2.3 hours (±2.9) to reach goal HR. The total dose of diltiazem was similar for patients <100 kg and ≥100 kg (28.7 vs 34.3 mg; P = .068) as was the time to reach goal HR (2.3 vs 2.3 hours; P = .949), respectively. No differences were noted in incidence of hypotension, bradycardia or need for additional rate control agents. WHAT IS NEW AND CONCLUSION: No difference in the total amount of diltiazem or time to reach goal HR was found in patients according to body weight stratification.

Burden of stroke in Italy: an economic model highlights savings arising from reduced disability following thrombolysis.

BACKGROUND: The consequences of stroke must be assessed not only in terms of incidence and mortality rates, but also in terms of disability, which may persist long after the acute phase. Thrombolysis, if timely administered, can effectively reduce post-stroke disability. AIMS: The economic model presented herein aims to evaluate, in eligible patients, the effects of alteplase on post-stroke disability and related costs over three-years. METHODS: The economic analysis was developed on the basis of four key components: clinical outcomes from international trials, economic consequences extracted from cost of illness studies, regulatory data from national and international agencies, and national epidemiological data. A population-level model estimated the difference in disability costs between patients treated with standard care versus those receiving thrombolytic therapy within 4×5 h of acute ischemic stroke. The analysis covered 36 months from discharge. RESULTS: Reduced costs related to post-stroke disability were observed in treated patients compared with those receiving standard care (control). The overall savings were €2330×15 per average patient: €1445×81 during the first 18 months, €362×25 between 18 and 24 months, and €522×09 in the 24-36 months period. The overall savings on 3174 Italian treated patients in 2013 were €7 395 907 over three-years. CONCLUSION: Our study reveals that performing thrombolytic therapy in eligible patients improves economic outcomes compared with patients receiving standard care. This model is useful for decision makers, both within and outside of the Italian national context, as a tool to assess the cost-effectiveness of thrombolysis in both short- and long-term period.

Formative research activities to provide Web-based nutrition education to adults in the Upper Rio Grande Valley.

The Internet is a promising new tool for disseminating cancer prevention information. Barriers to full implementation include disparities in access and skill and availability of information relevant at the local level. A nutrition education Web site to promote fruit and vegetable intake is being produced for a tri-ethnic adult population in Colorado and New Mexico. Development is guided by findings from formative research including focus groups with local residents, a survey on computer and Internet use with 200 adults in 1998, an assessment of public access computer sites, and in-depth discussion with local community computer skills trainers.

Solution NMR structure and backbone dynamics of the major cold-shock protein (CspA) from Escherichia coli: evidence for conformational dynamics in the single-stranded RNA-binding site.

The major cold-shock protein (CspA) from Escherichia coli is a single-stranded nucleic acid-binding protein that is produced in response to cold stress. We have previously reported its overall chain fold as determined by NMR spectroscopy [Newkirk, K., Feng, W., Jiang, W., Tejero, R., Emerson, S. D., Inouye, M., and Montelione, G. T. (1994) Proc. Natl. Acad. Sci. U.S.A. 91, 5114-5118]. Here we describe the complete analysis of 1H, 13C, and 15N resonance assignments for CspA, together with a refined solution NMR structure based on 699 conformational constraints and an analysis of backbone dynamics based on 15N relaxation rate measurements. An extensive set of triple-resonance NMR experiments for obtaining the backbone and side chain resonance assignments were carried out on uniformly 13C- and 15N-enriched CspA. Using a subset of these triple-resonance experiments, the computer program AUTOASSIGN provided automatic analysis of sequence-specific backbone N, Calpha, C', HN, Halpha, and side chain Cbeta resonance assignments. The remaining 1H, 13C, and 15N resonance assignments for CspA were then obtained by manual analysis of additional NMR spectra. Dihedral angle constraints and stereospecific methylene Hbeta resonance assignments were determined using a new conformational grid search program, HYPER, and used together with longer-range constraints as input for three-dimensional structure calculations. The resulting solution NMR structure of CspA is a well-defined five-stranded beta-barrel with surface-exposed aromatic groups that form a single-stranded nucleic acid-binding site. Backbone dynamics of CspA have also been characterized by 15N T1, T2, and heteronuclear 15N-1H NOE measurements and analyzed using the extended Lipari-Szabo formalism. These dynamic measurements indicate a molecular rotational correlation time taum of 4.88 +/- 0.04 ns and provide evidence for fast time scale (taue < 500 ps) dynamics in surface loops and motions on the microsecond to millisecond time scale within the proposed nucleic acid-binding epitope.

A novel RNA-binding motif in influenza A virus non-structural protein 1.

The solution NMR structure of the RNA-binding domain from influenza virus non-structural protein 1 exhibits a novel dimeric six-helical protein fold. Distributions of basic residues and conserved salt bridges of dimeric NS1(1-73) suggest that the face containing antiparallel helices 2 and 2' forms a novel arginine-rich nucleic acid binding motif.

Structural characterization of an analog of the major rate-determining disulfide folding intermediate of bovine pancreatic ribonuclease A.

The major rate-determining step in the oxidative regeneration of bovine pancreatic ribonuclease A (RNase A) proceeds through des-[40-95] RNase A, a three-disulfide intermediate lacking the Cys40-Cys95 disulfide bond. An analog of this intermediate, [C40A, C95A] RNase A, has been characterized in terms of regular backbone structure and thermodynamic stability at pH 4.6. Nearly complete backbone 1H, 15N, and 13C resonances, and most 13Cbeta side-chain resonances have been assigned for the mutant RNase A using triple-resonance NMR data and a computer program, AUTOASSIGN, for automated analysis of resonance assignments. Comparisons of chemical shift data, 3J(1HN-1Halpha) coupling constants, and NOE data for the mutant and wild-type proteins reveal that the overall chain folds of the two proteins are very similar, with localized structural perturbations in the regions spatially adjacent to the mutation sites in [C40A, C95A] RNase A. More significantly, 1H/2H amide exchange and thermodynamic data reveal a global destabilization of the mutant protein characterized by a significant difference in the midpoint of the thermal transition curves (DeltaTm of 21.8 degrees C) and a significant increase in the slowest exchanging backbone amide 1H/2H exchange rates (10(2)-10(6)-fold faster in the hydrophobic core of [C40A, C95 A] RNase A). Comparisons of the entropy DeltaS degrees (T) and enthalpy DeltaH degrees (T) of unfolding between wild-type and [C40A, C95A] RNase A reveal that some of the global destabilization of the mutant protein arises from entropic and enthalpic changes in the folded state. Implications of these observations for understanding the role of des-[40-95] in the folding pathway of RNase A are discussed.

High-resolution solution NMR structure of the Z domain of staphylococcal protein A.

Staphylococcal protein A (SpA) is a cell-wall-bound pathogenicity factor from the bacterium Staphylococcus aureus. Because of their small size and immunoglobulin (IgG)-binding activities, domains of protein A are targets for protein engineering efforts and for the development of computational approaches for de novo protein folding. The NMR solution structure of an engineered IgG-binding domain of SpA, the Z domain (an analog of the B domain of SpA), has been determined by simulated annealing with restrained molecular dynamics on the basis of 671 conformational constraints. The Z domain contains three well-defined alpha-helices corresponding to polypeptide segments Lys7 to Leu17 (helix 1), Glu24 to Asp36 (helix 2), and Ser41 to Ala54 (helix 3). A family of ten conformers representing the solution structure of the Z domain was computed by simulated annealing of restrained molecular dynamics using the program CONGEN. The average of the root-mean-square deviations (r.m. s.d.) of the individual NMR conformers, relative to the mean coordinates, for the backbone atoms N, Calpha and C' of residues Phe5 through Ala56 is 0.69 A; the corresponding backbone r.m.s.d. for the three-helical core is 0.44 A. Helices 1, 2 and 3 are antiparallel in orientation (Omega12=-170(+/-4) degrees , Omega13=+16(+/-3) degrees , Omega23=+173(+/-7) degrees ). A comparison of backbone amide hydrogen/deuterium exchange rates in free and IgG-bound Z domains demonstrates that the amide protons of helices 1, 2 and 3 are protected from rapid exchange in both states, indicating that all three helices are also intact in the IgG-bound state. These solution NMR results differ from the previously determined X-ray structure of the similar SpA B domain in complex with the Fc fragment of a human IgG antibody, where helix 3 is not observed in the electron density map and from the solution NMR structure of the B domain, where helix 3 is observed but helix 1 is tilted by approximately 30 degrees with respect to helices 2 and 3. Hydrogen-bonded N-cap and C-cap formation is observed for all three helices of the Z domain; these capping interactions appear to be highly conserved in the five homologous domains of SpA.

NMR structural analysis of an analog of an intermediate formed in the rate-determining step of one pathway in the oxidative folding of bovine pancreatic ribonuclease A: automated analysis of 1H, 13C, and 15N resonance assignments for wild-type and [C65S, C72S] mutant forms.

A three-disulfide intermediate, des-[65-72] RNase A, lacking the disulfide bond between Cys65 and Cys72, is formed in one of the rate-determining steps of the oxidative regeneration pathways of bovine pancreatic ribonuclease A (RNase A). An analog of this intermediate, [C65S, C72S] RNase A, has been characterized in terms of structure and thermodynamic stability. Triple-resonance NMR data were analyzed using an automated assignment program, AUTOASSIGN. Nearly all backbone 1H, 13C, and 15N resonances and most side-chain 13C(beta) resonances of both wild-type (wt) and [C65S, C72S] RNase A were assigned unambiguously. Analysis of NOE, 13C(alpha) chemical shift, and 3J(H(N)-H(alpha)) scalar coupling data indicates that the regular backbone structure of the major form of [C65S, C72S] RNase A is very similar to that of the major form of wt RNase A, although small structural differences are indicated in the mutation site and in spatially adjacent beta-sheet structures comprising the hydrophobic core. Thermodynamic analysis demonstrates that [C65S, C72S] RNase A (Tm of 38.5 degrees C) is significantly less stable than wt RNase A (Tm of 55.5 degrees C) at pH 4.6. Although the structural comparison of wt RNase A and this analog of an oxidative folding intermediate indicates only localized effects around the Cys65 and Cys72 sites, these thermodynamic measurements indicate that formation of the fourth disulfide bond, Cys65-Cys72, on this oxidative folding pathway results in global stabilization of the native chain fold. This conclusion is supported by comparisons of amide 1H/2H exchange rates which are significantly faster throughout the entire structure of [C65S, C72S] RNase A than in wt RNase A. More generally, our study indicates that the C65-C72 disulfide bond of RNase A contributes significantly in stabilizing the structure of the hydrophobic core of the native protein. Formation of this disulfide bond in the final step of this oxidative folding pathway provides significant stabilization of the native-like structure that is present in the corresponding three-disulfide folding intermediate.

Automated analysis of protein NMR assignments using methods from artificial intelligence.

An expert system for determining resonance assignments from NMR spectra of proteins is described. Given the amino acid sequence, a two-dimensional 15N-1H heteronuclear correlation spectrum and seven to eight three-dimensional triple-resonance NMR spectra for seven proteins, AUTOASSIGN obtained an average of 98% of sequence-specific spin-system assignments with an error rate of less than 0.5%. Execution times on a Sparc 10 workstation varied from 16 seconds for smaller proteins with simple spectra to one to nine minutes for medium size proteins exhibiting numerous extra spin systems attributed to conformational isomerization. AUTOASSIGN combines symbolic constraint satisfaction methods with a domain-specific knowledge base to exploit the logical structure of the sequential assignment problem, the specific features of the various NMR experiments, and the expected chemical shift frequencies of different amino acids. The current implementation specializes in the analysis of data derived from the most sensitive of the currently available triple-resonance experiments. Potential extensions of the system for analysis of additional types of protein NMR data are also discussed.

Automated analysis of nuclear magnetic resonance assignments for proteins.

Recent developments in protein NMR technology provide spectral data that are highly amendable to analysis by computer software systems. Automated methods of analysis use constraint satisfaction, pseudoenergy minimization, directed search, neural net, simulated annealing, and/or genetic algorithms to establish sequential links and sequence-specific assignments. The most advanced systems provide automated analysis of complete backbone and extensive side-chain resonance assignments for proteins of 50-150 amino acids.

Reading, readability, and legibility research: implications for notification letters.

This article defines communication science and then briefly describes three research areas relevant to worker notifications: (1) receiving of notification messages, (2) reading and understanding of notification messages, and (3) influences or effects of notification messages on workers. Next, the article focuses on the reading and legibility research relevant to worker notifications and then provides 16 guidelines for drafting worker notifications. Finally, the article suggests evaluating draft notifications by using one or more of the following: skilled editorial reviews, readability scoring, Cloze techniques, signal stopping techniques, in-depth personal interviews, focus groups, and usability testing.

A constraint reasoning system for automating sequence-specific resonance assignments from multidimensional protein NMR spectra.

AUTOASSIGN is a prototype expert system designed to aid in the determination of protein structure from nuclear magnetic resonance (NMR) measurements. In this paper we focus on one of the key steps of this process, the assignment of the observed NMR signals to specific atomic nuclei in the protein; i.e. the determination of sequence-specific resonance assignments. Recently developed triple-resonance (1H, 15N, and 13C) NMR experiments [Montelione et al., 1992] have provided an important breakthrough in this field, as the resulting data are more amenable to automated analysis than data sets generated using conventional strategies [Wuethrich, 1986]. The "assignment problem" can be stated as a constraint satisfaction problem (CSP) with some added complexities. There is very little internal structure to the problem, making it difficult to apply subgoaling and problem decomposition. Moreover, the data used to generate the constraints are incomplete, non-unique, and noisy, and constraints emerge dynamically as analysis progresses. The traditional inference engine is replaced by a set of very tightly-coupled modules which enforce extensive constraint propagation, with state information distributed over the objects whose relationships are being constrained. AUTOASSIGN provides correct and nearly complete resonance assignments with both simulated and real 3D triple-resonance data for a 72 amino acid protein.

Effect of contraceptive steroids on arginine-stimulated glucagon and insulin secretion in women. III. Medroxyprogesterone acetate.

The effect of medroxyprogesterone acetate (MPA) on basal circulating lipids, arginine-stimulated glucagon and insulin secretion, and glucose tolerance was studied in normal women. After 5 days of oral MPA treatment (10 mg/day), there was a small but significant decline in basal circulating triglycerides. No changes were observed in fasting plasma concentrations of cholesterol, free fatty acids, glucagon, insulin, or glucose; in the plasma glucagon, insulin, or glucose responses during L-arginine infusion; or in the plasma insulin or glucose responses during oral glucose tolerance tests. There was no correlation of any of these parameters with the observed decline in fasting plasma triglyceride concentrations. These results confirm previous reports of no consistent changes in lipid or glucose homeostasis in women using derivatives of 17alpha-acetoxyprogesterone derivatives for contraceptive purposes, and suggest that MPA may be a suitable alternative for those women who develop hyperlipemia or glucose intolerance when they use contraceptive agents which contain derivatives of ethinyl estradiol and nortestosterone.

Solitary thyroid nodules.

A study was made of 67 patients with solitary thyroid nodules in which strict criteria to eliminate the probability of cancer, including a history of radiation to the neck, were used. Twelve (17.9%) were found to have histologic malignancy. This figure is threefold that of a study made by one of the authors 11 years earlier, but comparable to others more recently reported from cancer centers elsewhere. It is not certain whether the apparent increase is actual or merely the result of more careful screening of patients for referral. Shrinking of the nodule by thyroid suppression therapy had been definite but incomplete in three nodules, one of which was found to be malignant. Excision is recommended for all persistent thyroid nodules.