Klebsiella pneumoniae clinical isolates with features of both multidrug-resistance and hypervirulence have unexpectedly low virulence.

Klebsiella pneumoniae has been classified into two types, classical K. pneumoniae (cKP) and hypervirulent K. pneumoniae (hvKP). cKP isolates are highly diverse and important causes of nosocomial infections; they include globally disseminated antibiotic-resistant clones. hvKP isolates are sensitive to most antibiotics but are highly virulent, causing community-acquired infections in healthy individuals. The virulence phenotype of hvKP is associated with pathogenicity loci responsible for siderophore and hypermucoid capsule production. Recently, convergent strains of K. pneumoniae, which possess features of both cKP and hvKP, have emerged and are cause of much concern. Here, we screen the genomes of 2,608 multidrug-resistant K. pneumoniae isolates from the United States and identify 47 convergent isolates. We perform phenotypic and genomic characterization of 12 representative isolates. These 12 convergent isolates contain a variety of antimicrobial resistance plasmids and virulence plasmids. Most convergent isolates contain aerobactin biosynthesis genes and produce more siderophores than cKP isolates but not more capsule. Unexpectedly, only 1 of the 12 tested convergent isolates has a level of virulence consistent with hvKP isolates in a murine pneumonia model. These findings suggest that additional studies should be performed to clarify whether convergent strains are indeed more virulent than cKP in mouse and human infections.

Pt+(C2H2)n Complexes Studied with Selected-Ion Infrared Spectroscopy.

Platinum cation complexes with multiple acetylene molecules are studied with mass spectrometry and infrared laser spectroscopy. Complexes of the form Pt+(C2H2)n are produced in a molecular beam by laser vaporization, analyzed with a time-of-flight mass spectrometer, and selected by mass for studies of their vibrational spectroscopy. Photodissociation action spectra in the C-H stretching region are compared to the spectra predicted for different structural isomers using density functional theory. The comparison between experiment and theory demonstrates that platinum forms cation-π complexes with up to three acetylene molecules, producing an unanticipated asymmetric structure for the three-ligand complex. Additional acetylenes form solvation structures around this three-ligand core. Reacted structures that couple acetylene molecules (e.g., to form benzene) are found by theory to be energetically favorable, but their formation is inhibited under the conditions of these experiments by large activation barriers.

Adsorption and degradation of neonicotinoid insecticides in agricultural soils.

The adsorption and degradation of seven commercially available neonicotinoid insecticides in four types of agricultural soils from three states (Mississippi, Arkansas, and Tennessee) in the USA were studied. The adsorptions of all the neonicotinoids fit a linear isotherm. The adsorption distribution coefficients (Kd) were found to be below 2.0 L/kg for all the neonicotinoids in all the soils from Mississippi and Arkansas. Only in the Tennessee soil samples, the Kd ranged from 0.96 to 4.21 L/kg. These low values indicate a low affinity and high mobility of these insecticides in the soils. The soil organic carbon-water partitioning coefficient Koc ranged from 349 to 2569 L/kg. These Kd values showed strong positive correlations with organic carbon content of the soils. The calculated Gibbs energy change (ΔG) of these insecticides in all the soils ranged from - 14.6 to - 19.5 kJ/mol, indicating that physical process was dominant in the adsorptions. The degradations of all these neonicotinoids in the soils followed a first-order kinetics with half-lives ranging from 33 to 305 days. The order of the insecticides with decreasing degradation rate is as follows: clothianidin > thiamethoxam > imidacloprid > acetamiprid > dinotefuran > thiacloprid > nitenpyram. The moisture content, clay content, and cation exchange capacity showed positive effects on the degradation rate of all the neonicotinoids. The Groundwater Ubiquity Score (GUS) calculated from the adsorption distribution coefficient, organic content, and half-life indicates that, except for thiacloprid, all the neonicotinoids in all the soils are possible leachers, having potentials to permeate into and through groundwater zones.

Coordination and Spin States in Fe+(C2H2)n Complexes Studied with Selected-Ion Infrared Spectroscopy.

Fe+(acetylene)n ion-molecule complexes are produced in a supersonic molecular beam with pulsed laser vaporization. These ions are mass selected and studied with infrared photodissociation spectroscopy in the C-H stretching region, complemented by computational chemistry calculations. All C-H stretch vibrations are shifted to frequencies lower than the vibrations of isolated acetylene because of the charge transfer that occurs between the metal ion and the molecules. Complexes in the size range of n = 1-4 are found to have structures with individual acetylene molecules bound to the core metal ion via cation-π interactions. The coordination is completed with four ligands in a structure close to a distorted tetrahedron. Larger complexes in the range of n = 5-8 have external acetylene molecules solvating this n = 4 core ion via CH-π bonding to inner-shell ligands. DFT computations predict that quartet spin states are more stable for all complex sizes, but infrared spectra for quartet and doublet spin states are quite similar, precluding definitive determination of the spin states. There is no evidence for any of these complexes having acetylenes coupled into reacted structures. This is consistent with computed thermochemistry, which finds significant activation barriers to such reactions.

Coordination and Solvation in Gas-Phase Ag+(C2H2)n Complexes Studied with Selected-Ion Infrared Spectroscopy.

Silver-acetylene cation complexes of the form Ag+(C2H2)n (n = 1-9) were produced via laser ablation in a supersonic expansion of acetylene/argon. The ions were mass selected and studied via infrared laser photodissociation spectroscopy in the C-H stretching region (3000-3500 cm-1). Fragmentation patterns indicate that four ligands are strongly coordinated to the metal cation. Density functional theory calculations were performed in support of the experimental data. Together, infrared spectroscopy and theory provide insight into the structure and bonding of these complexes. The Ag+(C2H2)n (n = 1-4) species are shown to be η2-bonded, cation-π complexes with red-shifted C-H stretches on the acetylene ligands. Unlike Cu+(C2H2)n and Au+(C2H2)n complexes, which have a maximum coordination of three, silver cation is tetrahedrally coordinated to four acetylene ligands. Larger complexes (n = 5-9) are formed by solvation of the Ag+(C2H2)4 core with acetylene. Similar to Cu+(C2H2)n and Au+(C2H2)n complexes, acetylene solvation leads to new and interesting infrared band patterns that are quite distinctive from those of the smaller complexes.

Infrared Spectroscopy of Zn(Acetylene)n+ Complexes: Ligand Activation and Nascent Polymerization.

Zinc-acetylene ion-molecule complexes were produced by laser vaporization in a supersonic expansion. These complexes were mass selected and studied with infrared laser photodissociation spectroscopy complemented by computational chemistry. The combined approach of infrared spectroscopy and theory provides information on the structures and bonding of these complexes, as well as evidence for intracluster reactions. Fragmentation patterns demonstrate that the coordination number of strongly bonded ligands is three. Infrared spectra compared to those predicted by theory allow identification of different isomers at each cluster size. The coordination in these complexes varies between η2 and η1 metal-acetylene connections. Structures based on η2 bonding form a symmetric D3h configuration for the n = 3 complex. This unreactive core ion forms larger clusters with only weakly bonded acetylene in solvation structures. Structures based on three η1-bonded acetylenes form a near-C3v core ion which is the doorway configuration for subsequent reactions. Electron transfer to the next (fourth) acetylene produces a metal-carbon bond and a trans-bent metal-vinyl structure with a terminal radical site. This radical site attaches a fifth acetylene to produce a vinyl-dimer structure. Evidence for continued reactions in the larger clusters is obscured by solvating acetylenes with more intense IR bands. The asymmetric coordination of zinc cations and the critical configuration with three-fold coordination that leads to reactivity are new features of intracluster metal-molecular reactions.

Microsolvation in V+(H2O)n Clusters Studied with Selected-Ion Infrared Spectroscopy.

Gas-phase ion-molecule clusters of the form V+(H2O)n (n = 1-30) are produced by laser vaporization in a supersonic expansion. These ions are analyzed and mass-selected with a time-of-flight mass spectrometer and investigated with infrared laser photodissociation spectroscopy. The small clusters (n ≤ 7) are studied with argon tagging, while the larger clusters are studied via the elimination of water molecules. The vibrational spectra for the small clusters include only free O-H stretching vibrations, while larger clusters exhibit redshifted hydrogen bonding vibrations. The spectral patterns reveal that the coordination around V+ ions is completed with four water molecules. A symmetric square-planar structure forms for the n = 4 ion, and this becomes the core ion in larger structures. Clusters up to n = 8 have mostly two-dimensional structures, but hydrogen bonding networks evolve to three-dimensional structures in larger clusters. The free O-H vibration of acceptor-acceptor-donor (AAD)-coordinated surface molecules converges to a frequency near that of bulk water by the cluster size of n = 30. However, the splitting of this vibration for AAD- versus AD-coordinated molecules is still different compared to other singly charged or doubly charged cation-water clusters. This indicates that cation identity and charge-site location in the cluster can produce discernable spectral differences for clusters in this size range.

Cyclotrimerization of Acetylene in Gas Phase V+(C2H2)n Complexes: Detection of Intermediates and Products with Infrared Spectroscopy.

Infrared laser spectroscopy and mass spectrometry were used to determine the structures of intermediates and products in the single-atom-catalyzed trimerization of acetylene to form benzene. Complexes of the form V+(C2H2)n were produced in the gas phase via laser ablation in a pulsed-nozzle source, size-selected with a mass spectrometer, and studied with infrared laser photodissociation spectroscopy. Density functional theory calculations were performed in support of the experiments. Single- and double-acetylene complexes form V+(C2H2)n metallacycle structures. Three-acetylene complexes exhibit a surprising dependence on the acetylene concentration, forming V+(C2H2)3 and (C2H2)V+(C4H4) tri- and dimetallacycle ion structures at low concentrations and eventually V+(benzene) at higher concentrations. These observations reveal intermediates along the reaction path of acetylene cyclotrimerization to benzene.

Spinal Instrumentation in Growing Children Retards the Natural Development of Pelvic Incidence.

BACKGROUND: Pelvic incidence increases gradually throughout growth until skeletal maturity. Growing rod instrumentation has been suggested to have a stabilizing effect on the development of the normal sagittal spinal alignment. The purpose of this study is to determine the effect of fixed sagittal plane caused by dual growing rod instrumentation on the natural progression of sagittal spinopelvic parameters in children with idiopathic or idiopathic-like early onset scoliosis. METHODS: Hospital records of children with growing rod instrumentation from 4 separate institutions were reviewed retrospectively. Inclusion criteria were idiopathic or idiopathic-like early onset scoliosis, treatment with dual growing rods with lower instrumented vertebra L4 or upper and more than 2 years of follow-up. Instrumentation levels, magnitudes of major curve, thoracic kyphosis (T2-T12), lumbar lordosis (L1-S1) and pelvic incidence were recorded from preoperative and postoperative standing whole-spine radiographs. Estimated pelvic incidence was also calculated for each patient as if their spines had not been instrumented using the previous normative data. RESULTS: A total of 37 patients satisfied the inclusion criteria. Average age at initial surgery was 7.4±1.8 years (range, 4 to 12 y). Mean follow-up time was 71±26 months (range, 27 to 120 mo). Mean preoperative Cobb angle of 59±13.5 (range, 30 to 86) degrees was reduced to 35.1±17.5 (range, 11 to 78) degrees at the last follow-up. Mean preoperative T2-T12 kyphosis angle was 46.2±14.9 degrees (range, 22 to 84 degrees). At the latest follow-up, it was 44.8±16.2 degrees (range, 11 to 84 degrees) (P=0.93). Mean L1-S1 lordosis angle was 50.5±10.7 degrees (range, 30 to 72 degrees) preoperatively. At the latest follow-up, mean L1-S1 lordosis angle was 48.8±12.7 degrees (range, 26 to 74 degrees) (P=0.29). Mean preoperative pelvic incidence was 45.7±7.9 degrees (range, 30 to 68 degrees). At the latest follow-up, it was 46.7±8.4 degrees (range, 34 to 72 degrees) (P=0.303). The estimated average pelvic incidence was 49.5 degrees (P=0.012). CONCLUSIONS: Previously reported developmental changes of the sagittal spinal parameters were not observed in children who underwent posterior spinal instrumentation. Our findings suggest that spinal instrumentation impedes the natural development of the sagittal spinal profile. LEVEL OF EVIDENCE: Level IV-this is a retrospective case-series.

Photodegradation of clothianidin and thiamethoxam in agricultural soils.

Presented in this paper is a study on the photodegradation of two widely used neonicotinoid insecticides clothianidin and thiamethoxam in three soils and in solid phase. The effects of light with differing wavelengths were examined using the natural sunlight and single ultraviolet A (UVA) and ultraviolet B (UVB) light sources. The results indicated that UVB played a key role in the photodegradation of clothianidin and thiamethoxam while the effects of visible and UVA lights were negligible. The degradations of clothianidin and thiamethoxam under all the light sources followed the first-order kinetics, and the half-lives of clothianidin and thiamethoxam in the three soils under the sunlight ranged from 97 to 112 h and 88 to 103 h, respectively. When clothianidin and thiamethoxam were directly exposed to the sunlight without soil, the degradation rates were remarkably higher with half-lives being 13 and 10 h, respectively. Therefore, the insecticides fallen on the surface of soils would be degraded under sunlight much faster than those that enter the soils. The examination of the degradation products revealed four compounds from the photodegradation of clothianidin and three from thiamethoxam, and clothianidin was one of the photodegradation products of thiamethoxam.

Effects of cupric chloride on coagulation in human plasma: role of fibrinogen.

INTRODUCTION: Copper poisoning is associated with severe multiorgan injury and potentially death if chelation therapy is not administered. Of interest, while important gastrointestinal and urinary tract hemorrhage is associated with copper poisoning, very little is known concerning the nature of copper induced coagulopathy. METHODS: Using thrombelastography, we assessed changes in coagulation kinetics in human plasma following exposure to copper concentrations encountered during poisoning. RESULTS: While time to commence coagulation was not compromised, both velocity of thrombus growth and final strength were diminished. This result was duplicated with one concentration of copper in factor XIII deficient plasma. This pattern of coagulation kinetic response was interpreted as copper mediated fibrinogen dysfunction, perhaps via oxidation of key fibrinogen disulfide bridges. Lastly, experiments wherein glutathione was added implicated copper generated radical oxygen species as one of the mechanisms responsible for compromised coagulation kinetics. CONCLUSIONS: While chelation therapy is the key to survival following copper poisoning, perhaps this and future investigations of how copper affects coagulation may provide insight into effective supportive therapy for patients with active bleeding.

Amino acid racemization and its relation to geochronology and archaeometry.

Amino acid racemization, used as a method of relative and quantitative dating of fossils, evaluates the degree of postmortem conversion of l to d amino acid enantiomers. While extensively utilized, this method has garnered confusion due to controversial age estimates for human fossils in North America in the 1970s. This paper explains the age controversy and aftermath, current chromatographic methods used in research, mathematical calibration models, and a short synopsis of other dating techniques in geochronology and archaeometry.

Potent Pyrimidine and Pyrrolopyrimidine Inhibitors of Testis-Specific Serine/Threonine Kinase†2 (TSSK2).

Testis-specific serine/threonine kinase 2 (TSSK2) is an important target for reversible male contraception. A high-throughput screen of ≈17 000 compounds using a mobility shift assay identified two potent series of inhibitors having a pyrrolopyrimidine or pyrimidine core. The pyrrolopyrimidine 10 (IC50 22 nm; GSK2163632A) and the pyrimidine 17 (IC50 31 nm; ALK inhibitor 1) are the most potent TSSK2 inhibitors in these series, which contain the first sub-100 nanomolar inhibitors of any TSSK isoform reported, except for the broad kinase inhibitor staurosporine. The novel, potent pyrimidine TSSK2 inhibitor compound 19 (IC50 66 nm; 2-[[5-chloro-2-[2-methoxy-4-(1-methylpiperidin-4-yl)anilino]pyrimidin-4-yl]amino]-N-methylbenzenesulfonamide) lacks the potential for metabolic activation. Compound 19 had a potency rank order of TSSK1>TSSK2>TSSK3>TSSK6, indicating that potent dual inhibitors of TSSK1/2 can be identified, which may be required for a complete contraceptive effect. The future availability of a TSSK2 crystal structure will facilitate structure-based discovery of selective TSSK inhibitors from these pyrrolopyrimidine and pyrimidine scaffolds.

BET Bromodomain Inhibitors with One-Step Synthesis Discovered from Virtual Screen.

Chemical inhibition of epigenetic regulatory proteins BrdT and Brd4 is emerging as a promising therapeutic strategy in contraception, cancer, and heart disease. We report an easily synthesized dihydropyridopyrimidine pan-BET inhibitor scaffold, which was uncovered via a virtual screen followed by testing in a fluorescence anisotropy assay. Dihydropyridopyimidine 3 was subjected to further characterization and is highly selective for the BET family of bromodomains. Structure-activity relationship data and ligand deconstruction highlight the importance of the substitution of the uracil moiety for potency and selectivity. Compound 3 was also cocrystallized with Brd4 for determining the ligand binding pose and rationalizing subsequent structure-activity data. An additional series of dihydropyridopyrimidines was synthesized to exploit the proximity of a channel near the ZA loop of Brd4, leading to compounds with submicromolar affinity and cellular target engagement. Given these findings, novel and easily synthesized inhibitors are being introduced to the growing field of bromodomain inhibitor development.

Is There Value in Having Radiology Provide a Second Reading in Pediatric Orthopaedic Clinic?

BACKGROUND: The Joint Commission on Accreditation of Healthcare Organizations specifically mandates the dual interpretation of musculoskeletal radiographs by a radiologist in addition to the orthopaedist in all hospital-based orthopaedic clinics. Previous studies have questioned the utility of this practice. The purpose of this study was to further investigate the clinical significance of having the radiologist provide a second interpretation in a hospital-based pediatric orthopaedic clinic. METHODS: A retrospective review was performed of all patients who had plain radiographs obtained in the pediatric orthopaedic clinic at an academic children's hospital over a 4-month period. For each radiographic series, the orthopaedist's note and the radiology interpretation were reviewed and a determination was made of whether the radiology read provided new clinically useful information and/or a new diagnosis, whether it recommended further imaging, or if it missed a diagnosis that was reflected in the orthopaedist's note. The hospital charges associated with the radiology read for each study were also quantified. RESULTS: The charts of 1570 consecutive clinic patients who were seen in the pediatric orthopaedic clinic from January to April, 2012 were reviewed. There were 2509 radiographic studies performed, of which 2264 had both a documented orthopaedist's note and radiologist's read. The radiologist's interpretation added new, clinically important information in 1.0% (23/2264) of these studies. In 1.7% (38/2264) of the studies, it was determined that the radiologist missed the diagnosis or clinically important information that could affect treatment. The total amount of the professional fees charged for the radiologists' interpretations was $87,362. On average, the hospital charges for each occurrence in which the radiologist's read provided an additional diagnosis or clinically important information beyond the orthopaedist's note were $3798. CONCLUSIONS: The results of this study suggest that eliminating the requirement to have the radiologist interpret radiographs in the pediatric orthopaedic clinic would have few clinical consequences. LEVEL OF EVIDENCE: Level III-This is a diagnostic retrospective cohort study.

Survival, Reproduction and Growth of the Marine Amphipod, Leptocheirus plumulosus, Following Laboratory Exposure to Copper-Spiked Sediment.

Leptocheirus plumulosus was exposed for 28 days to Cu-spiked sediment at mean concentrations ranging from 44.4 to 605 mg Cu/kg dry sediment in a sediment/water test system designed to simulate natural conditions. The NOEC (no observed effect concentration)-LOEC (lowest observed effect concentration) range for the most sensitive endpoint of growth was 199-414 mg Cu/kg sediment. An IC50 for reproduction was estimated at 187 mg Cu/kg sediment. Mean Cu concentrations in pore water (PW) where significant effects were observed were 25.8 and 59.0 µg/L, while their respective concentrations in overlying water (OW) were 22.1 and 28.0 µg Cu/L. Copper concentrations were ≤19.1 and <16.6 µg/L in PW and OW, respectively, at lower exposures where effects were not evident. Concentrations of Cu in marine sediment lower than sediment quality guidelines based on geochemical factors of acid volatile sulfide, organic carbon content (f OC), and sediment grain size (i.e., silt + clay) would appear not to result in adverse effects toward L. plumulosus.

Ritual drinks in the pre-Hispanic US Southwest and Mexican Northwest.

Chemical analyses of organic residues in fragments of pottery from 18 sites in the US Southwest and Mexican Northwest reveal combinations of methylxanthines (caffeine, theobromine, and theophylline) indicative of stimulant drinks, probably concocted using either cacao or holly leaves and twigs. The results cover a time period from around A.D. 750-1400, and a spatial distribution from southern Colorado to northern Chihuahua. As with populations located throughout much of North and South America, groups in the US Southwest and Mexican Northwest likely consumed stimulant drinks in communal, ritual gatherings. The results have implications for economic and social relations among North American populations.

Survival and Growth of the Marine Polychaete, Neanthes arenaceodentata, Following Laboratory Exposure to Copper-Spiked Sediment.

Juvenile marine polychaetes, Neanthes arenaceodentata, were exposed for 28 days to copper (Cu)-spiked sediment at six concentrations ranging from 48.3 to 2380 mg Cu/kg dry sediment, plus control. Survival was reduced (p ≤ 0.05) at concentrations ≥1190 mg Cu/kg. Growth was inhibited at Cu concentrations ≥506 mg Cu/kg. Dose-response relationships yielded LC10 and LC50 estimates of 514 and 1230 mg Cu/kg, respectively. The growth effect EC50 estimate was 409 mg Cu/kg. Ranges for the no observable effect concentration and lowest observable effect concentration were 506-1190 mg Cu/kg for survival, and 230-506 mg Cu/kg for growth. Pore water concentrations of Cu were 38.7-65.8 µg Cu/L in exposures where toxic effects were observed, compared to a range of 15.1-22.4 µg Cu/L in exposures where significant effects were not evident. The results of the study were compared with empirical and mechanistic sediment quality guidelines for the protection of benthic organisms.