Pharmacokinetics of ceftiofur sodium in equine pregnancy.

Eleven pregnant pony mares (D270-326) were administered ceftiofur sodium intramuscularly at 2.2 mg/kg (n = 6) or 4.4 mg/kg (n = 5), once daily.

Assessing the accuracy of self-reported self-talk.

As with most kinds of inner experience, it is difficult to assess actual self-talk frequency beyond self-reports, given the often hidden and subjective nature of the phenomenon. The Self-Talk Scale (STS; Brinthaupt et al., 2009) is a self-report measure of self-talk frequency that has been shown to possess acceptable reliability and validity.

TLR2-dependent inhibition of macrophage responses to IFN-gamma is mediated by distinct, gene-specific mechanisms.

Mycobacterium tuberculosis uses multiple mechanisms to avoid elimination by the immune system. We have previously shown that M. tuberculosis can inhibit selected macrophage responses to IFN-gamma through TLR2-dependent and -independent mechanisms.

Carbene proton attachment energies: theoretical study.

The geometries and electronic energies of six singlet carbenes, with methyl and phenyl substituents, and the corresponding carbenium ions were obtained using several density functional theory (DFT) variants and the second-order Møller-Plesset method for electron correlation and compared with G3 results, with the aim to determine a relatively low-cost computational protocol that is sufficiently accurate for the specific molecules and ions of interest. Some additional calculations were performed at the CCSD(T) level. Results for diphenylcarbene, methylphenylcarbene, and their cations, which were not previously investigated by ab initio methods, are reported as are calculations on methylene, methylcarbene, dimethylcarbene, and phenylcarbene.

The agr radiation: an early event in the evolution of staphylococci.

Agr is a global regulatory system in the staphylococci, operating by a classical two-component signaling module and controlling the expression of most of the genes encoding extracellular virulence factors. As it is autoinduced by a peptide, encoded within the locus, that is the ligand for the signal receptor, it is a sensor of population density or a quorum sensor and is the only known quorum-sensing system in the genus. agr is conserved throughout the staphylococci but has diverged along lines that appear to parallel speciation and subspeciation within the genus.

Surface compositions of carbon sorbents exposed to simulated low-rank coal flue gases.

Bench-scale testing of elemental mercury (Hg0) sorption on selected activated carbon sorbents was conducted to develop a better understanding of the interaction among the sorbent, flue gas constituents, and Hg0. The results of the fixed-bed testing under simulated lignite combustion flue gas composition for activated carbons showed some initial breakthrough followed by increased mercury (Hg) capture for up to approximately 4.8 hr.

Catalytic effects of carbon sorbents for mercury capture.

Activated carbon sorbents have the potential to be an effective means of mercury control in combustion systems. Reactions of activated carbons in flow systems with mercury and gas stream components were investigated to determine the types of chemical interactions that occur on the sorbent surface. The effects of carbon type, particle size, temperature, and reactive gases were studied.

Structural and functional characterization of OmpF porin mutants selected for larger pore size. I. Crystallographic analysis.

OmpF porin is a nonspecific pore protein from the outer membrane of Escherichia coli. Previously, a set of mutants was selected that allow the passage of long maltodextrins that do not translocate through the wild-type pore. Here, we describe the crystal structures of four point mutants and one deletion mutant from this set; their functional characterization is reported in the accompanying paper (Saint, N.

Redundant homosexual F transfer facilitates selection-induced reversion of plasmid mutations.

F plasmids use surface exclusion to prevent the redundant entry of additional F plasmids during active growth of the host cells. This mechanism is relaxed during stationary phase and nonlethal selections, allowing homosexual redundant plasmid transfer. Homosexual redundant transfer occurs in stationary-phase liquid cultures, within nongrowing populations on solid media, and on media lacking a carbon source.

Characterization of a new rho mutation that relieves polarity of Mu insertions.

We report the identification and characterization of a new rho mutation, rho614, that relieves polarity of Mu insertions in Escherichia coli. The mutation was identified by its ability to suppress the polarity of the Mu-mediated phi(lamB'-'lacZ)hyb61-4 fusion that is located at codon four of the lamB signal sequence. The rho614 mutation alters residue 80 in the proposed RNA-binding domain of Rho and is recessive to wild-type rho.

Redundant transfer of F' plasmids occurs between Escherichia coli cells during nonlethal selections.

Surface exclusion is the mechanism by which F plasmids prevent the redundant entry of additional F plasmids into the host cell during exponential growth. This mechanism is relaxed in cells that are in stationary phase. Using genetically marked F' plasmids and host strains, we extend this finding to Escherichia coli populations during extended nonlethal selection in bacterial lawns.

Isolation and characterization of a generalized transducing phage for Xanthomonas campestris pv. campestris.

We have isolated and characterized a lytic double-stranded DNA Xanthomonas campestris pv. campestris bacteriophage (XTP1) capable of mediating generalized transduction. The phage transduces chromosomal markers at frequencies of 10(-5) to 10(-6) transductants per PFU.

Biochemical analysis of the biogenesis and function of the Escherichia coli export factor SecY.

SecY is an integral plasma-membrane protein of Escherichia coli which is essential for the export of periplasmic and outer-membrane proteins containing cleavable signal sequences. We have synthesized SecY in vitro using an E. coli transcription/translation system.

OmpC and OmpF porins influence viability and culturability of Escherichia coli cells incubated in seawater.

The contribution of the major outer membrane porins OmpF and OmpC to the maintenance of viability and culturability of Escherichia coli cells in seawater was analyzed using isogenic mutant strains lacking one or both porins. Cells that possessed OmpF and OmpC survived better than those lacking one or both of them. However, the results differed, depending on whether the cells were adapted to high osmolarity or not before transfer to seawater.

Phenotypic expression of the Pseudomonas syringae pv. syringae 61 hrp/hrm gene cluster in Escherichia coli MC4100 requires a functional porin.

Plants, in general, appear to be able to detect the presence of incompatible Pseudomonas syringae strains by a hypothetical cell-cell recognition process to initiate inducible defense mechanisms that contribute to disease resistance. A 25-kb hrp/hrm gene cluster isolated from P. syringae pv.

Mutant bias in nonlethal selections results from selective recovery of mutants.

We have characterized a nonlethal selection for mutations that allow Escherichia coli to grow on large maltodextrins (Dex+) in the absence of the lamB encoded maltoporin LamB. These Dex+ mutations occur before and after imposition of the selection and the selection does not result in a general increase in mutagenesis. The recovered Dex+ mutations are almost exclusively mutations that alter the ompF gene that encodes a major E.

Determinants of OmpF porin antigenicity and structure.

Sixty-six murine hybridomas raised to Escherichia coli B/r porin were used to identify and differentiate the epitopes of this outer membrane protein. Anti-porin monoclonal antibodies (mAb) were raised against outer membrane fragments, purified native trimeric porin (trimer), and purified sodium dodecyl sulfate-denatured monomeric porin (monomer). Immunochemical and flow cytometric methods identified five distinct cell surface-exposed determinants on OmpF.

A novel mutation, cog, which results in production of a new porin protein (OmpG) of Escherichia coli K-12.

A mutant of Escherichia coli K-12 which produces a new outer membrane protein, OmpG, was isolated and genetically and biochemically characterized. The presence of OmpG allows growth on maltodextrins in the absence of the LamB maltoporin. The data obtained from in vivo growth and uptake experiments suggested that the presence of the OmpG protein results in an increase in outer membrane permeability for small hydrophilic compounds.

Identification and characterization of a new gene of Escherichia coli K-12 involved in outer membrane permeability.

Using a genetic selection for mutations which allow large maltodextrins to cross the outer membrane of Escherichia coli in the absence of the LamB maltoporin, we have obtained and characterized two mutations that define a new locus of E. coli. We have designated this locus imp for increased membrane permeability.

Mutations that alter the pore function of the OmpF porin of Escherichia coli K12.

We describe the isolation and characterization of mutations in ompF that alter the pore properties of the OmpF porin. The selection makes use of the fact that maltodextrins larger than maltotriose are too large to diffuse through the normal OmpF pore. By demanding growth on maltodextrins (Dex+) in the absence of the LamB protein, which is normally required for the uptake of these large sugars, we are able to obtain ompF mutations.

Genetic identification of the pore domain of the OmpC porin of Escherichia coli K-12.

We have isolated and characterized 31 mutations in the ompC gene which allow Escherichia coli to grow on maltotriose (Dex+) in the absence of the LamB and OmpF porins. These ompC(Dex) mutations include single-base-pair substitutions, small deletions, and small insertions. DNA sequence analysis shows that all of the alterations occur within the coding region for the first 110 amino acids of mature OmpC.

Isolation and characterization of OmpC porin mutants with altered pore properties.

The LamB protein is normally required for the uptake of maltodextrins. Starting with a LamB- OmpF- strain, we have isolated mutants that will grow on maltodextrins. The mutation conferring the Dex+ phenotype in the majority of these mutants has been mapped to the ompC locus.

Signal sequence mutations that alter coupling of secretion and translation of an Escherichia coli outer membrane protein.

The lamB701-708 signal sequence mutation reduces expression of LamB, an outer membrane protein of Escherichia coli. To investigate the possibility that synthesis and export of LamB are coupled, as suggested by the expression defect of the lamB701-708 mutation, we isolated intragenic suppressors of the lamB701-708 mutation. The expression defect imposed by the lamB701-708 mutation is suppressed by an export-defective signal sequence mutation, suggesting that translation and export are coupled.