Rapid emergence of daptomycin resistance in clinical isolates of Corynebacterium striatum a cautionary tale.

The objective of this study was to investigate the observation of daptomycin resistance in Corynebacterium striatum, both in vivo and in vitro. We describe a case of C. striatum bacteremia in a patient with a left ventricular assist device (LVAD); the initial isolate recovered was daptomycin susceptible with a minimum inhibitory concentration (MIC) of 0.125 µg/ml. Two months later, and after daptomycin therapy, the individual became bacteremic with an isolate of C. striatum with a daptomycin MIC of >256 µg/ml. To study the prevalence of daptomycin resistance in C. striatum, clinical isolates of C. striatum were grown in broth culture containing daptomycin to investigate the emergence of resistance to this antimicrobial. Molecular typing was used to evaluate serial isolates from the index patient and the clinical isolates of C. striatum we assayed. In vitro analysis of isolates from the index patient and 7 of 11 additional C. striatum isolates exhibited the emergence of high-level daptomycin resistance, despite initially demonstrating low MICs to this antimicrobial agent. This phenotype was persistent even after serial subculture in the absence of daptomycin. Together, these data demonstrate that caution should be taken when using daptomycin to treat high-inoculum infections and/or infections of indwelling medical devices with C. striatum. To our knowledge, this is the first report characterizing the emergence of daptomycin resistance in C. striatum.

Everolimus versus mycophenolate mofetil in heart transplantation: a randomized, multicenter trial.

In an open-label, 24-month trial, 721 de novo heart transplant recipients were randomized to everolimus 1.5 mg or 3.0 mg with reduced-dose cyclosporine, or mycophenolate mofetil (MMF) 3 g/day with standard-dose cyclosporine (plus corticosteroids ± induction). Primary efficacy endpoint was the 12-month composite incidence of biopsy-proven acute rejection, acute rejection associated with hemodynamic compromise, graft loss/retransplant, death or loss to follow-up. Everolimus 1.5 mg was noninferior to MMF for this endpoint at month 12 (35.1% vs. 33.6%; difference 1.5% [97.5% CI: -7.5%, 10.6%]) and month 24. Mortality to month 3 was higher with everolimus 1.5 mg versus MMF in patients receiving rabbit antithymocyte globulin (rATG) induction, mainly due to infection, but 24-month mortality was similar (everolimus 1.5 mg 10.6% [30/282], MMF 9.2% [25/271]). Everolimus 3.0 mg was terminated prematurely due to higher mortality. The mean (SD) 12-month increase in maximal intimal thickness was 0.03 (0.05) mm with everolimus 1.5 mg versus 0.07 (0.11) mm with MMF (p < 0.001). Everolimus 1.5 mg was inferior to MMF for renal function but comparable in patients achieving predefined reduced cyclosporine trough concentrations. Nonfatal serious adverse events were more frequent with everolimus 1.5 mg versus MMF. Everolimus 1.5 mg with reduced-dose cyclosporine offers similar efficacy to MMF with standard-dose cyclosporine and reduces intimal proliferation at 12 months in de novo heart transplant recipients.

Clinical course and predictors of pericardial effusion following cardiac transplantation.

OBJECTIVE: Pericardial effusions occur frequently after orthotopic heart transplantation. There have been conflicting reports describing etiology, prognosis, and outcomes associated with these early postoperative effusions. METHODS: A retrospective review of 91 patients transplanted between January 2001 and September 2004 was performed. Pericardial effusion was defined by serial echocardiography and graded as none, small, moderate, or large. A total of 1088 echocardiograms were evaluated during the first posttransplant year. Perioperative variables were evaluated by logistic regression analysis to define predictors for occurrence of effusions. RESULTS: Echocardiographic data were available for 88 patients. Thirty-one patients (35%) developed moderate to large effusion in the immediate postoperative period. Three patients developed hemodynamic compromise that required immediate intervention. All other effusions resolved within 3 months of heart transplantation without any specific intervention. Only prolonged donor ischemic time was associated with higher risk of occurrence of moderate to large pericardial effusions (odds ratio 1.012, 95% confidence interval 1.001 to 1.019, P = .033). There was no difference in morbidity or early mortality between patients with and without pericardial effusions. CONCLUSION: Moderate to large pericardial effusions occur frequently after heart transplantation. In a vast majority, these effusions are not associated with any adverse clinical outcomes and resolve within 3 months postoperatively. Early postoperative close monitoring is still required to evaluate for tamponade.

Influence of trophic status on PCB distribution in lake sediments and biota.

We investigated the relationship between trophic status and polychlorinated biphenyl (PCB) distribution in 19 Swedish lakes. We analyzed PCB in water, phytoplankton, zooplankton, fish and sediment during two sampling periods, in spring and summer. The mass of sigma PCB in the lake sediments was positively related to lake trophy, i.e. more PCBs were accumulated and buried in the sediment of eutrophic lakes than in oligotrophic lakes. In the oligotrophic lakes a greater fraction of the total PCB load was dissolved in water. We conclude that this is a result of higher sedimentation rates in eutrophic lakes and relatively lower turnover of organic carbon in the water column of the shallow, eutrophic lakes. In the stratified lakes, the amount of PCB per cubic meter in the epilimnion decreased from spring to summer. We suggest that sedimentation of plankton beneath the thermocline during stratification act as a sink process of PCBs from the epilimnion.

Sequence analysis of four atrazine-resistant mutants from Rhodopseudomonas viridis.

Four atrazine-resistant mutants from the purple bacterium Rhodopseudomonas viridis were isolated. Sequence analysis revealed three different mutant strains carrying mutations in the herbicide-binding pocket: i) MAV 2: L212-Glu----Lys, ii) MAV 3: L216-Phe----Ser and iii) MAV 4 = MAV 5: L217-Arg----His, L220-Val----Leu. Except MAV 3 all Rps. viridis mutants are different from those selected by their resistance towards the closely related triazine terbutryn.

Tacrolimus with mycophenolate mofetil (MMF) or sirolimus vs. cyclosporine with MMF in cardiac transplant patients: 1-year report.

The most advantageous combination of immunosuppressive agents for cardiac transplant recipients has not yet been established. Between November 2001 and June 2003, 343 de novo cardiac transplant recipients were randomized to receive steroids and either tacrolimus (TAC) + sirolimus (SRL), TAC + mycophenolate mofetil (MMF) or cyclosporine (CYA) + MMF. Antilymphocyte induction therapy was allowed for up to 5 days. The primary endpoint of >/=3A rejection or hemodynamic compromise rejection requiring treatment showed no significant difference at 6 months (TAC/MMF 22.4%, TAC/SRL 24.3%, CYA/MMF 31.6%, p = 0.271) and 1 year (p = 0.056), but it was significantly lower in the TAC/MMF group when compared only to the CYA/MMF group at 1 year (23.4% vs. 36.8%; p = 0.029). Differences in the incidence of any treated rejection were significant (TAC/SRL = 35%, TAC/MMF = 42%, CYA/MMF = 59%; p < 0.001), as were median levels of serum creatinine (TAC/SRL = 1.5 mg/dL, TAC/MMF = 1.3 mg/dL, CYA/MMF = 1.5 mg/dL; p = 0.032) and triglycerides (TAC/SRL = 162 mg/dL, TAC/MMF = 126 mg/dL, CYA/MMF = 154 mg/dL; p = 0.028). The TAC/SRL group encountered fewer viral infections but more fungal infections and impaired wound healing. These secondary endpoints suggest that the TAC/MMF combination appears to offer more advantages than TAC/SRL or CYA/MMF in cardiac transplant patients, including fewer >/=3A rejections or hemodynamic compromise rejections and an improved side-effect profile.

Nuclear charge radii of 9,11Li: the influence of halo neutrons.

The nuclear charge radius of 11Li has been determined for the first time by high-precision laser spectroscopy. On-line measurements at TRIUMF-ISAC yielded a 7Li-11Li isotope shift (IS) of 25 101.23(13) MHz for the Doppler-free [FORMULA: SEE TEXT]transition. IS accuracy for all other bound Li isotopes was also improved. Differences from calculated mass-based IS yield values for change in charge radius along the isotope chain. The charge radius decreases monotonically from 6Li to 9Li, and then increases from 2.217(35) to 2.467(37) fm for 11Li. This is compared to various models, and it is found that a combination of halo neutron correlation and intrinsic core excitation best reproduces the experimental results.

ATP leakage from ELD cells after exposure to stearic, monochlorostearic, dichlorostearic, and oleic acids.

The capacity of stearic, monochlorostearic, dichlorostearic and oleic acids to cause membrane damage was measured as their ability to induce leakage of adenosine triphosphate (ATP) from mammalian tumour cells in vitro. Chlorinated stearic acids, and oleic acid, caused ATP leakage at lower concentrations than normal stearic acid. The membrane disturbing properties are suggested to be a result of the different molecular geometries of the chlorinated stearic acids, and oleic acid, compared to non-chlorinated stearic acid.

Plasmin-mediated activation of contact system in response to pharmacological thrombolysis.

BACKGROUND: Thrombin activity increases in patients treated with coronary thrombolysis for acute myocardial infarction, but the mechanisms are not well defined. We have shown that thrombin activity increases in plasma and whole blood incubated with plasminogen activators and appears to be plasmin mediated and dependent on activity of the factor VIIIa/IXa complex. METHODS AND RESULTS: In the present study, increases in thrombin activity induced by incubation of recalcified citrated plasma with 0.16 to 0.5 mumol/L plasmin at 37 degrees C were markedly attenuated in recalcified citrated plasma deficient in factors XI or XII, prekallikrein, or high molecular weight kininogen, as well as in plasma incubated with plasmin in the presence of 3.5 mumol/L corn trypsin inhibitor, a specific factor XIIa inhibitor. Increases in thrombin activity also occurred in nonanticoagulated whole blood incubated with pharmacological concentrations of plasminogen activators and were markedly attenuated in the presence of corn trypsin inhibitor. Plasmin-mediated (0.25 mumol/L) activation of purified factor XII occurred in 0.05 mol/L Tris-HCl and 0.012 mol/L NaCl (pH 7.8) at 37 degrees C, resulting in equimolar quantities of two fragments that corresponded to cleavage of factor XII at Arg353-Val354, the site involved in kallikrein-mediated activation of factor XII, and cleavage at Lys346-Ser347, an apparently novel site of plasmin-mediated hydrolysis of factor XII. Contact activation was also demonstrated in plasma samples from patients after treatment with fibrinolytic agents for myocardial infarction, by demonstrating cleavage of high molecular weight kininogen from its one-chain to its two-chain form by ligand blotting with 125I-prekallikrein. CONCLUSIONS: Plasmin-mediated activation of the contact system of coagulation appears to account, at least in part, for increases in procoagulant activity in patients treated with fibrinolytic agents. It may also explain hypotension, by release of bradykinin from high molecular weight kininogen, and complement activation, by activated factor XII, that has been demonstrated in these patients.

Effect of oligochaete bioturbation on sediment accumulation of 2,2',4,4'-tetrachlorobiphenyl.

The influence of clay content, organic carbon, and bioturbation on sediment accumulation of 2,2',4,4'-tetrachlorobiphenyl (TCB) was investigated in microcosms. Four types of sediments differing in porosity, density, organic carbon, and clay content were used in the study. The sediments, with or without oligochaete bioturbation, were exposed for 100 days to water with a constant concentration of 14C-labeled TCB, in a continuous-flow system. The hypothesis for the experiment was that bioturbation would enhance the accumulation rate of TCB by redistributing the sediment particles and/or by changing the physical properties, e.g., porosity of the sediment, in a way that would increase the diffusion rate. The highest accumulation was found in sediments of low organic carbon content. No effect of clay content was found. Contrary to the hypothesis, bioturbation did not increase sediment accumulation of TCB. Instead, the sediment accumulation could be explained by retarded diffusion, a combined effect of the processes of adsorption and diffusion.

The relationship of soluble fibrin and cross-linked fibrin degradation products to the clinical course of myocardial infarction.

Recently, increases in the plasma concentration of soluble fibrin (SF) have been suggested to be sensitive and specific for myocardial infarction (MI). However, the relationship between elevations in the SF concentration and the onset of symptoms and clinical course of MI is unknown. In addition, there are no data regarding the relationship between SF concentrations and concentrations of other markers of procoagulant (fibrinopeptide A [FPA]) and fibrinolytic (cross-linked fibrin degradation products [XL-FDPs]) activity in patients with MI. In this study, concentrations of SF were measured with a novel antigen-based assay for 93 MI patients and 29 control subjects, and the relationship between SF concentrations and those of XL-FDPs and FPA was determined. Increases in SF, FPA, and XL-FDP concentrations were documented in 55.9%, 45.2%, and 73.9%, respectively, of patients with MI, but there was no relationship between the concentrations of these markers. Increases in the concentration of SF or XL-FDPs did not show a relationship to increases in the concentration of FPA. Concentrations of XL-FDPs but not of SF were elevated to a greater extent in patients with MI complications (defined as death, ventricular arrhythmia, severe congestive heart failure, or mural thrombus). Increases in SF and XL-FDPs were not sensitive enough for the diagnosis of MI, but increased concentrations of XL-FDPs appear to predict those patients who are at higher risk for MI-related complications.

Hyperfine splitting, isotope shift, and level energy of the 3S states of (6,7)Li.

We study the 2S-3S transition of (6,7)Li by high-precision laser spectroscopy using two-photon Doppler-free excitation and photoionization detection. Interferometric cross referencing to metrologic Rb 3S-5D two-photon transitions allowed measurement of the transition isotope shift and hyperfine splitting in the 3S state with precision at the 30 kHz level. The results are IS=11 453.734(30) MHz, A(3S)(6Li)=35.263(15) MHz, and A(3S)(7Li)=93.106(11) MHz. Combined with recent theoretical work, the isotope shift yields a new value for the change in squared nuclear charge radii DeltaR(2)=0.47(5) fm(2). This is compared with other work and some existing discrepancies are resolved.

Evidence that serine L223 is involved in the proton transfer pathway to QB in the photosynthetic reaction center of Rhodopseudomonas viridis.

In the reaction center of purple photosynthetic bacteria, the reducing equivalents produced by primary charge separation are exported via an ubiquinone molecule working as a two-electron shuttle. This loosely-bound quinone, called QB, accepts in successive flashes two electrons from the tightly bound primary quinone acceptor QA, along with two protons from the external medium. The surrounding protein plays an important role in stabilizing the semiquinone anion and in providing a pathway for protons from the cytoplasmic phase to QB. Herbicides of the triazine type compete with QB for the binding pocket and their binding is controlled by nearby amino acid residues. We have studied the kinetics of the first and second electron transfer from QA to QB in two herbicide-resistant mutants from Rhodopseudomonas viridis, T1 (ArgL217-->His,Ser L223-->Ala) and MAV5 (Arg L217-->His, Val L220-->Leu), in order to determine whether these residues are involved in proton transfer to the reduced QB. The main effect of the mutant T1 was a drastic (600-fold at pH 7) decrease in the rate of the second electron transfer to QB compared to the wild type. In contrast, the rate of the second electron transfer in the mutant MAV5 was decreased only slightly (10-fold) in the pH range from 7 to 11. We attribute the inhibition of the second electron transfer in the Ser L223-->Ala mutation to an essential role of Ser L223 in the donation of the first proton to the reduced QB.(ABSTRACT TRUNCATED AT 250 WORDS)

Structural and functional consequences of a Glu L212-->Lys mutation in the QB binding site of the photosynthetic reaction center of Rhodopseudomonas viridis.

The properties of the quinone acceptor complex in the photosynthetic reaction center of the atrazine-resistant Rhodopseudomonas viridis mutant A2 (Glu L212-->Lys) were studied by EPR spectroscopy and by photoelectric measurements. The EPR signal attributed to the semiquinone-iron (QB-Fe2+) was significantly different from wild type and resembled that found in PS II. Essentially normal oscillations of QB-Fe2+ were observed upon flash illumination. The kinetics of the first and the second electron transfer from QA to QB were characterized by a photoelectric double-flash method. Compared to wild type, the rate of the first electron transfer in the large majority of reaction centers was decreased drastically from k1 = (18 microseconds)-1 in the wild type to (70 ms)-1 in the mutant, whereas the second electron transfer was only slightly slowed down with a rate of k2 = (260 microseconds)-1 compared to (65 microseconds)-1 in wild type (pH 7). When the pH was raised above 10, in a major fraction of the reaction centers a fast kinetics of the first electron transfer, like that in wild type, reappeared. The experimental results are interpreted as an effect of the positive charge on the lysine causing a significant structural change of the QB binding pocket and a strongly diminished affinity for ubiquinone. The slow QA(-)-->QB electron transfer kinetics are thus attributed to ubiquinone binding, which is rate limiting. The possible role of the residue Glu L212, which is conserved in all purple bacteria, in electron and proton transfer to QB is discussed.

DGAT1, a new positional and functional candidate gene for intramuscular fat deposition in cattle.

Intramuscular fat content, also assessed as marbling of meat, represents an important beef quality trait. Recent work has mapped a quantitative trait locus (QTL) with an effect on marbling to the centromeric region of bovine chromosome 14, with the gene encoding thyroglobulin (TG) being proposed as a positional and functional candidate gene for this QTL. Recently, the gene encoding diacylglycerol O-acyltransferase (DGAT1), which also has been mapped within the region of the marbling QTL, has been demonstrated to affect the fat content of milk. In the present study, the effects of a 5'-polymorphism of TG and of a lysine/alanine polymorphism of DGAT1 on the fat content of musculus (m.) semitendinosus and m. longissimus dorsi in 55 bovine animals (28 German Holstein and 27 Charolais) has been investigated. Significant effects were found for both candidate genes in both the breeds. These effects seem to be independent of one another because the alleles of the two polymorphisms showed no statistically significant disequilibrium. The DGAT1 effect is mainly on the m. semitendinosus. The TG polymorphism only affects m. longissimus dorsi. However, both intramuscular fat enhancing effects seem to be recessive. The possibility of two linked loci, acting recessively on intramuscular fat content, will require special strategies when selecting for higher marbling scores.

Beta-globin gene cluster haplotype distribution in five Brazilian Indian tribes.

Haplotypes derived from five polymorphic restriction sites in the beta-globin gene cluster were investigated in 139 individuals from five different Brazilian Indian tribes by the polymerase chain reaction (PCR). Eight haplotypes were identified. Haplotypes 2 ((+)----) and 6 (-)++(-)+) were the most frequent and were common to all tribes. Their prevalences ranged from 60% to 93% and from 3% to 18%, respectively. Average heterozygosity measured by the Gini-Simpson index is markedly reduced among these Brazilian Indians when compared with Europeans (56%), but much less (8%) in relation to Asiatics, suggesting the absence of an important bottleneck effect in the early colonization of South America. The coefficient of gene differentiation (GST') was estimated as 0.082 among six Brazilian Indian tribes, but when only three Tupi-Mondé-speaking tribes were considered, this estimate was reduced to 0.030.

In vivo and in vitro toxicity of fractionated fish lipids, with particular regard to their content of chlorinated organic compounds.

Six different lipid matrices (the intact lipid (IL), four lipid fractions with different polarity, and the free fatty acids (FFAs) obtained by hydrolysis of the triacylglycerol (TAG) containing fraction) were obtained from salmon (Salmo salar) and eel (Anguilla anguilla), each collected at a contaminated and a comparatively uncontaminated catch site along the coast of Scandinavia. The lipid matrices were studied in toxicological test systems representing various biological functions of different organ systems from several species and trophic levels. The results were evaluated with particular respect to the concentrations of extractable organically bound chlorine (EOC1) in the matrices tested. In some test systems, the specimens with a higher EOC1 concentration appeared to be more toxic. For example, the TAG containing fraction (F2) from Idefjord eel, having a higher EOC1 content than F2 from Oslofjord eel, reduced the number and hatchability of eggs laid by zebrafish. Both IL and F2 of Idefjord eel increased mortality and reduced the oxygen/nitrogen-ratio in blue mussels. Non-polar compounds (F1) from Bothnian Sea salmon induced 7-ethoxyresurofin O-deethylase (EROD) activity in rainbow trout hepatocytes, whereas F1 from Senja salmon did not. F1 from Bothnian Sea salmon also reduced the number of T-cells in foetal mouse thymus analagen in vitro compared with the cell number in anlagen exposed to F1 from Senja salmon. A positive correlation between EOC1 concentration and test response was found for EROD activity in rainbow trout hepatocytes and for ATP-leakage in Erlich ascites tumour cells when testing the phospolipid containing fraction (F4). However, in most test systems the fish oils, irrespective of EOC1 content, were of low toxicity, and the observed effects need to be verified in future studies.

Nuclear charge radii of 8,9Li determined by laser spectroscopy.

The 2s-->3s transition of (6,7,8,9)Li was studied by high-resolution laser spectroscopy using two-photon Doppler-free excitation and resonance-ionization detection. Hyperfine structure splittings and isotope shifts were determined with precision at the 100 kHz level. Combined with recent theoretical work, the changes in the nuclear-charge radii of (8,9)Li were determined. These are now the lightest short-lived isotopes for which the charge radii have been measured. It is found that the charge radii monotonically decrease with increasing neutron number from 6Li to 9Li.