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Break Point (break + point)
Selected AbstractsPRECLINICAL STUDY: Morphine withdrawal decreases responding reinforced by sucrose self-administration in progressive ratioADDICTION BIOLOGY, Issue 2 2007Dengke Zhang ABSTRACT Previous studies have shown that withdrawal from psychostimulant drugs such as d -amphetamine or methamphetamine decreases motivation to work for a natural reinforcement, which is thought to be associated with the withdrawal-induced depressive state and hypofunction of the mesolimbic dopamine system. However, to our knowledge, studies exploring the effect of morphine withdrawal on motivation for a natural reinforcement are lacking. The purpose of the present study was to examine whether motivation to work for a natural reinforcement changes during morphine withdrawal. Three groups of male Sprague,Dawley rats were trained to respond on a nose poke for a 4% sucrose solution under a progressive ratio schedule and were subsequently administered a 10-day regimen of injection of high or low dose of morphine or saline. Their duration of break point and withdrawal symptoms were assessed. The finding showed that break points were significantly reduced on day 1 and persisted to at least day 10 of withdrawal without change in locomotor activity. There were hardly any differences bear mentioning when comparing the magnitude of the decrease between the high- and the low-dose group, whereas the withdrawal scales were significant greater in the high-dose group than in the low-dose group. The results suggest that the morphine withdrawal resulted in decreased motivation to obtain the natural reinforcement. The progressive ratio procedure may be a useful technique for evaluation of changes in motivation for natural reinforcing stimuli following withdrawal from opiates. [source] Preparation and properties of the single-walled carbon nanotube/cellulose nanocomposites using N -methylmorpholine- N -oxide monohydrateJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Dong-Hun Kim Abstract Single-walled carbon nanotube (SWNT)/cellulose nanocomposite films were prepared using N -methylmorpholine- N -oxide (NMMO) monohydrate as a dispersing agent for the acid-treated SWNTs (A-SWNTs) as well as a cellulose solvent. The A-SWNTs were dispersed in both NMMO monohydrate and the nanocomposite film (as confirmed by scanning electron microscopy) because of the strong hydrogen bonds of the A-SWNTs with NMMO and cellulose. The mechanical properties, thermal properties, and electric conductivity of the nanocomposite films were improved by adding a small amount of the A-SWNTs to the cellulose. For example, by adding 1 wt % of the A-SWNTs to the cellulose, tensile strain at break point, Young's modulus, and toughness increased , 5.4, , 2.2, and , 6 times, respectively, the degradation temperature increased to 9°C as compared with those of the pure cellulose film, and the electric conductivities at , (the wt % of A-SWNTs in the composite) = 1 and 9 were 4.97 × 10,4 and 3.74 × 10,2 S/cm, respectively. Thus, the A-SWNT/cellulose nanocomposites are a promising material and can be used for many applications, such as toughened Lyocell fibers, transparent electrodes, and soforth. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Properties of soy protein isolate/poly(vinyl alcohol) blend "green" films: Compatibility, mechanical properties, and thermal stabilityJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Jun-Feng Su Abstract Blend films from nature soy protein isolates (SPI) and synthetical poly(vinyl alcohol) (PVA) compatibilized by glycerol were successfully fabricated by a solution-casting method in this study. Properties of compatibility, mechanical properties, and thermal stability of SPI/PVA films were investigated based on the effect of the PVA concentration. XRD tests confirm that the SPI/PVA films were partially crystalline materials with peaks of 2, = 20°. And, the addition of glycerol will insert the crystalline structure and destroy the blend microstructure of SPI/PVA. Differential scanning calorimetry (DSC) tests show that SPI/PVA blend polymers have a single glass transition temperature (Tg) between 80 and 115.0°C, which indicate that SPI and PVA have good compatibility. The tension tests show that SPI/PVA films exhibit both higher tensile strength (,b) and percentage elongation at break point (P.E.B.). Thermogravimetric analysis (TGA) and water solubility tests show that SPI/PVA blend polymer has more stable stability than pure SPI. All the results reflect that SPI/PVA/glycerol blend film provides a convenient and promising way to prepare soy protein plastics for practical application. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] A hybrid forecasting approach for piece-wise stationary time seriesJOURNAL OF FORECASTING, Issue 7 2006Minxian Yang Abstract We consider the problem of forecasting a stationary time series when there is an unknown mean break close to the forecast origin. Based on the intercept-correction methods suggested by Clements and Hendry (1998) and Bewley (2003), a hybrid approach is introduced, where the break and break point are treated in a Bayesian fashion. The hyperparameters of the priors are determined by maximizing the marginal density of the data. The distributions of the proposed forecasts are derived. Different intercept-correction methods are compared using simulation experiments. Our hybrid approach compares favorably with both the uncorrected and the intercept-corrected forecasts.,,Copyright © 2006 John Wiley & Sons, Ltd. [source] Case study: a maintenance practice used with real-time telecommunications softwareJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 2 2001Miroslav Popovi Abstract In this paper we present a case study of the software maintenance practice that has been successfully applied to real-time distributed systems, which are installed and fully operational in Moscow, St. Petersburg, and other cities across Russia. In this paper we concentrate on the software maintenance process, including customer request servicing, in-field error logging, role of information system, software deployment, and software quality policy, and especially the software quality prediction process. In this case study, the prediction process is shown to be integral and one of the most important parts of the software maintenance process. We include a software quality prediction procedure overview and an example of the actual practice. The quality of the new software update is predicted on the basis of the current update's quantity metrics data and quality data, and new update's quantity metrics data. For management, this forecast aids software maintenance efficiency, and cost reduction. For practitioners, the most useful result presented is the process for determining the value for the break point. We end this case study with five lessons learned. Copyright © 2001 John Wiley & Sons, Ltd. [source] Influence of target type and RAF rule on the measurement of near point of convergenceOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 1 2007Paul M. Adler Abstract Purpose:, This study was designed to investigate if the use of different target types or the RAF rule affected the measurement of near point of convergence (NPC). Methods:, The subjects comprised three groups: (1) 20 children aged 6,9 years (2) 17 children aged 11,13 years (3) 14 adults aged 20,30 years. Five targets were used to measure the NPC: (1) pencil tip, (2) fingertip, (3) penlight, (4) N5 letter and (5) vertical line target on the RAF rule. Results:, There was no significant difference in NPC measurements between the pencil tip, fingertip and N5 target in free space. The penlight resulted in significantly more remote NPC break and recovery points compared with the fingertip and pencil tip (p < 0.05). The RAF rule influences the NPC obtained (p < 0.001). The greatest difference in NPC measurements was observed when comparing the RAF line target and the finger in free space; the former resulted in NPC values of 1.9 times (95% CI 1.6,2.2 times) as much as those obtained with the finger. Conclusions:, Use of the penlight and RAF rule resulted in a more distant NPC break point compared with other targets. The effect of the RAF rule was more apparent for more receded NPC points. [source] Break Point Estimation and Spurious Rejections With Endogenous Unit Root TestsOXFORD BULLETIN OF ECONOMICS & STATISTICS, Issue 5 2001Junsoo Lee This paper examines the accuracy of break point estimation using the endogenous break unit root tests of Zivot and Andrews (1992) and Perron (1997). We find that these tests tend to identify the break point incorrectly at one-period behind (TB -1) the true break point (TB), where bias in estimating the persistence parameter and spurious rejections are the greatest. In addition, this outcome occurs under the null and alternative hypotheses, and more so as the magnitude of the break increases. Consequences of utilizing these endogenous break tests are similar to (incorrectly) omitting the break term Bt in Perron's (1989) exogenous test. [source] Neonatal salt-wasting and 11 ,-hydroxylase deficiency in a child carrying a homozygous deletion hybrid CYP11B2 (aldosterone synthase),CYP11B1 (11 ,-hydroxylase)CLINICAL GENETICS, Issue 3 2004B Ezquieta This article reports the case of a boy diagnosed at 1.8 years of age with congenital adrenal hyperplasia due to 11 ,-hydroxylase deficiency. The patient showed salt-wasting episodes during the neonatal period. On molecular analysis, a homozygous deletion hybrid (CYP11B2,CYP11B1) involving the CYP11B locus at 8q24.3 was found. Southern blot analysis showed the break point of the chimera gene to be located before intron 5; sequence analysis identified it at exon 4 between codons 202 and 248. This CYP11B2(5,)/B1(3,) hybrid should lack aldosterone synthase activity (due to the CYP11B1 residues at exons 5 and 6), and the enzyme it codes for should not be promoted by adrenocorticotropic hormone (ACTH) (CYP11B2 promoter sequences). The patient phenotype , neonatal salt-wasting and 11 ,-hydroxylase deficiency , is in agreement with this hybrid structure. This is the first time a homozygous deletion hybrid generated by unequal crossover has been described in exon 4. This genetic lesion appears to be the reciprocal product from the recombination event that causes glucocorticoid-remediable aldosteronism, a duplication dominant allele (CYP11B2,CYP11B1/B2,CYP11B1) coding for additional aldosterone synthase activity regulated by ACTH. The clinical presentation of the condition in this patient contributes to the in vivo understanding of the regulation of this complex locus in which two ,duplicated' genes have evolved different regulatory and enzymatic activities involved in mineralocorticoid and glucocorticoid synthesis in the adrenal glands. The fact that this allele was first predicted and has now been documented clinically and molecularly in vivo is particularly noteworthy. [source] Gas-phase basicities for ions from bradykinin and its des-arginine analoguesJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2001Nigel P. Ewing Abstract Apparent gas-phase basicities (GBapps) for [M + H]+ of bradykinin, des-Arg1 -bradykinin and des-Arg9 -bradykinin have been assigned by deprotonation reactions of [M + 2H]2+ in a Fourier transform ion cyclotron resonance mass spectrometer. With a GBapp of 225.8 ± 4.2 kcal mol,1, bradykinin [M + H]+ is the most basic of the ions studied. Ions from des-Arg1 -bradykinin and des-Arg9 -bradykinin have GBapp values of 222.8 ± 4.3 kcal mol,1 and 214.9 ± 2.3 kcal mol,1, respectively. One purpose of this work was to determine a suitable reaction efficiency ,break point' for assigning GBapp values to peptide ions using the bracketing method. An efficiency value of 0.1 (i.e. approximately 10% of all collisions resulting in a deprotonation reaction) was used to assign GBapps. Support for this criterion is provided by the fact that our GBapp values for des-Arg1 -bradykinin and des-Arg9 -bradykinin are identical, within experimental error, to literature values obtained using a modified kinetic method. However, the GBapps for bradykinin ions from the two studies differ by 10.3 kcal mol,1. The reason for this is not clear, but may involve conformation differences produced by experimental conditions. The results may be influenced by salt-bridge conformers and/or by conformational changes caused by the use of a proton-bound heterodimer in the kinetic method. Factors affecting the basicities of these peptide ions are also discussed, and molecular modeling is used to provide information on protonation sites and conformations. The presence of two highly basic arginine residues on bradykinin results in its high GBapp, while the basicity of des-Arg1 -bradykinin ions is increased by the presence of two proline residues at the N-terminus. The proline residue in the second position folds the peptide chain in a manner that increases intramolecular hydrogen bonding to the protonated N-terminal amino group of the proline at the first position. Copyright © 2001 John Wiley & Sons, Ltd. [source] The behavior of specific sediment yield in different grain size fractions in the tributaries of the middle Yellow River as influenced by eolian and fluvial processesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 8 2008Jiongxin Xu Abstract Based on data from 35 stations on the tributaries of the Yellow River, annual specific sediment yield (Ys) in eight grain size fractions has been related to basin-averaged annual sand,dust storm days (Dss) and annual precipitation (Pm) to reveal the influence of eolian and fluvial processes on specific sediment yield in different grain size fractions. The results show that Ys in fine grain size fractions has the highest values in the areas dominated by the coupled wind,water process. From these areas to those dominated by the eolian process or to those dominated by the fluvial process, Ys tends to decrease. For relatively coarse grain size fractions, Ys has monotonic variation, i.e. with the increase in Dss or the decrease in Pm, Ys increases. This indicates that the sediment producing behavior for fine sediments is different from that for relatively coarse sediments. The results all show that Ys for relatively coarse sediments depends on the eolian process more than on the fluvial process, and the coarser the sediment fractions the stronger the dependence of the Ys on the eolian process. The Ys,Dss and Ys,Pm curves for fine grain size fractions show some peaks and the fitted straight lines for Ys,Dss and Ys,Pm relationships for relatively coarse grain size fractions show some breaks. Almost all these break points may be regarded as thresholds. These thresholds are all located in the areas dominated by the coupled wind,water process, indicating that these areas are sensitive for erosion and sediment production, to which more attention should be given for the purpose of erosion and sediment control. A number of regression equations were established, based which the effect of rainfall, sand,dust storms and surface material grain size on specific sediment yield can be assessed. Copyright © 2007 John Wiley & Sons, Ltd. [source] An Xp; Yq Translocation Causing a Novel Contiguous Gene Syndrome in Brothers with Generalized Epilepsy, Ichthyosis, and Attention DeficitsEPILEPSIA, Issue 12 2003Michael J. Doherty Summary:,Purpose: We describe two brothers with generalized epilepsy, attention deficits, congenital ichthyosis, and Leri,Weill dyschondrosteosis who harbor an unusual Xp; Yq translocation chromosome, resulting in a novel contiguous gene syndrome because of deletion of genes from the distal short arm of the X chromosome. Methods: Physical examination, neuropsychologic testing, EEG, and neuroimaging studies were performed. Because of their unusual phenotype, karyotyping, fluorescence in situ hybridization, and further molecular analyses were carried out to refine the break points of the underlying unbalanced sex chromosome rearrangement. Results: The subjects had generalized epilepsy, X-linked ichthyosis, Madelung deformities, mesomelia, normal intelligence, and attention deficits. The brothers' karyotype was unbalanced; they inherited a maternal derivative X chromosome. Deleted distal Xp genes included short-stature homeobox on the X chromosome (SHOX), aryl sulfatase E (ARSE), variably charged X-chromosome mRNA gene A (VCX-A), and steroid sulfatase (STS). The final karyotype was 46,Y,der(X)t(X; Y)(p22.3; q11.2).ish der(X) (DXZ1+, KAL+, STS-, SHOX-) mat. Conclusions: Loss of distal contiguous Xp genes resulted in a syndrome comprising bony deformities, ichthyosis, attention problems, and generalized epilepsy. Candidate epilepsy genes within the deleted segment, such as ASMT, a gene involved in the final synthesis of melatonin, are discussed. Cytogenetic analyses should be included in the clinical evaluation of patients with generalized epilepsy and complex phenotypes. [source] PRECLINICAL STUDY: Morphine withdrawal decreases responding reinforced by sucrose self-administration in progressive ratioADDICTION BIOLOGY, Issue 2 2007Dengke Zhang ABSTRACT Previous studies have shown that withdrawal from psychostimulant drugs such as d -amphetamine or methamphetamine decreases motivation to work for a natural reinforcement, which is thought to be associated with the withdrawal-induced depressive state and hypofunction of the mesolimbic dopamine system. However, to our knowledge, studies exploring the effect of morphine withdrawal on motivation for a natural reinforcement are lacking. The purpose of the present study was to examine whether motivation to work for a natural reinforcement changes during morphine withdrawal. Three groups of male Sprague,Dawley rats were trained to respond on a nose poke for a 4% sucrose solution under a progressive ratio schedule and were subsequently administered a 10-day regimen of injection of high or low dose of morphine or saline. Their duration of break point and withdrawal symptoms were assessed. The finding showed that break points were significantly reduced on day 1 and persisted to at least day 10 of withdrawal without change in locomotor activity. There were hardly any differences bear mentioning when comparing the magnitude of the decrease between the high- and the low-dose group, whereas the withdrawal scales were significant greater in the high-dose group than in the low-dose group. The results suggest that the morphine withdrawal resulted in decreased motivation to obtain the natural reinforcement. The progressive ratio procedure may be a useful technique for evaluation of changes in motivation for natural reinforcing stimuli following withdrawal from opiates. [source] Bilayer to micelle transition of DMPC and alcohol ethoxylate surfactants as studied by isoperibol calorimetryJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2005Leticia Barriocanal Abstract The interaction of dimyristoylphosphatidylcholine (DMPC) with non-ionic surfactants has been studied using isoperibol calorimetry. Phospholipid-surfactant systems were formed in the isoperibol calorimeter with varying amounts of surfactant and the change in enthalpy on formation was measured. Solubilization of the phospholipid lamellae was assessed as a decrease in the enthalpy of reaction of co-films containing DMPC and increasing amounts of three linear alcohol ethoxylate surfactants: C10H21(OCH2CH2)3OH, C10H21(OCH2CH2)5OH, or C12H25(OCH2CH2)7OH. The isoperibol calorimetry data for DMPC/surfactant/water systems were consistent with a theoretical three-stage model for the solubilization of phospholipids by surfactants, whereby phospholipid bilayers are transformed into mixed micelles with increasing amounts of surfactant. The results indicate that: (i) the interaction between phospholipid and surfactants results in a non-linear correlation between the enthalpy of reaction and the surfactant concentration; (ii) the structural stage of the lamellar to micelle transition (mixed bilayers, mixed micelles, or both) can be determined from calorimetric data; (iii) phase boundaries in the solubilization process (bilayer saturation, micelle saturation) can be identified as break points in the enthalpy-concentration curve; and (iv) increasing the hydrophilicity of the surfactant results in a decrease of the surfactant concentration producing the onset of solubilization. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1747,1755, 2005 [source] Antimicrobial Use in the Treatment of Calf DiarrheaJOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 1 2004Peter D. Constable Calves with diarrhea often have small intestinal overgrowth with Escherichia coli bacteria, regardless of the inciting cause for the diarrhea, and 30% of systemically ill calves with diarrhea have bacteremia, predominantly because of E coli. Antimicrobial treatment of diarrheic calves should therefore be focused against E coli in the small intestine and blood, the 2 sites of infection. Fecal bacterial culture and antimicrobial susceptibility testing is not recommended in calves with diarrhea because fecal bacterial populations do not accurately reflect small intestinal or blood bacterial populations and because the break points for susceptibility test results have not been validated. Antimicrobial efficacy is therefore best evaluated by the clinical response of a number of calves to treatment, with calves randomly assigned to treatment groups. Amoxicillin, chlortetracycline, neomycin, oxytetracycline, streptomycin, sulfachloropyridazine, sulfamethazine, and tetracycline administered PO are currently labeled in the United States for the treatment of calf diarrhea. On the basis of published evidence for the oral administration of these antimicrobial agents, only amoxicillin can be recommended for the treatment of diarrhea. Dosage recommendations are amoxicillin trihydrate (10 mg/kg PO q12h) or amoxicillin trihydrate-clavulanate potassium (12.5 mg combined drug/kg PO q12h) for at least 3 days; the latter constitutes extra-label drug use. Parenteral administration of broad-spectrum ,-lactam antimicrobials,eftiofur (2.2mg/kg IM orSCq12h) and amoxicillin or ampicillin (10 mg/kg IM q12h),rpotentiatedsulfonamides(25 mg/kg IV or IM q24h) is recommended for treating calves with diarrhea and systemic illness; both constitute extra-label drug use. In calves with diarrhea and no systemic illness (normal appetite for milk, no fever), it is recommended that the health of the calf be monitored and that oral or parenteral antimicrobials not be administered. [source] Determination of suppliers' optimal quantity discount schedules with heterogeneous buyersNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 1 2002Qinan Wang Abstract Although the quantity discount problem has been extensively studied in the realm of a single supplier and a single buyer, it is not well understood when a supplier has many different buyers. This paper presents an analysis of a supplier's quantity discount decision when there are many buyers with different demand and cost structures. A common discrete all-unit quantity discount schedule with many break points is used. After formulating the model, we first analyze buyers' responses to a general discrete quantity discount schedule. This analysis establishes a framework for a supplier to formulate his quantity discount decision. Under this framework, the supplier's optimal quantity discount schedule can be formulated and solved by a simple non-linear programming model. The applicability of the model is discussed with an application for a large U.S. distribution network. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 46,59, 2002; DOI 10.1002/nav.1052 [source] Temperature dependence of nitrate reductase in the psychrophilic unicellular alga Koliella antarctica and the mesophilic alga Chlorella sorokinianaPLANT CELL & ENVIRONMENT, Issue 7 2006VITTORIA DI MARTINO RIGANO ABSTRACT Temperature responses of nitrate reductase (NR) were studied in the psychrophilic unicellular alga, Koliella antarctica, and in the mesophilic species, Chlorella sorokiniana. Enzymes from both species were purified to near homogeneity by Blue Sepharose (Pharmacia, Uppsala, Sweden) affinity chromatography and high-resolution anion-exchange chromatography (MonoQ; Pharmacia; Uppsala, Sweden). Both enzymes have a subunit molecular mass of 100 kDa, and K. antarctica NR has a native molecular mass of 367 kDa. NR from K. antarctica used both NADPH and NADH, whereas NR from C. sorokiniana used NADH only. Both NRs used reduced methyl viologen (MVH) or benzyl viologen (BVH). In crude extracts, maximal NADH and MVH-dependent activities of cryophilic NR were found at 15 and 35 °C, respectively, and retained 77 and 62% of maximal activity, respectively, at 10 °C. Maximal NADH and MVH-dependent activities of mesophilic NR, however, were found at 25 and 45 °C, respectively, with only 33 and 23% of maximal activities being retained at 10 °C. In presence of 2 µm flavin adenine dinucleotide (FAD), activities of cryophilic NADH:NR and mesophilic NADH:NR were stable up to 25 and 35 °C, respectively. Arrhenius plots constructed with cryophilic and mesophilic MVH:NR rate constants, in both presence or absence of FAD, showed break points at 15 and 25 °C, respectively. Essentially, similar results were obtained for purified enzymes and for activities measured in crude extracts. Factors by which the rate increases by raising temperature 10 °C (Q10) and apparent activation energy (Ea) values for NADH and MVH activities measured in enzyme preparations without added FAD differed slightly from those measured with FAD. Overall thermal features of the NADH and MVH activities of the cryophilic NR, including optimal temperatures, heat inactivation (with/without added FAD) and break-point temperature in Arrhenius plots, are all shifted by about 10 °C towards lower temperatures than those of the mesophilic enzyme. Transfer of electrons from NADH to nitrate occurs via all three redox centres within NR molecule, whereas transfer from MVH requires Mo-pterin prosthetic group only; therefore, our results strongly suggest that structural modification(s) for cold adaptation affect thermodynamic properties of each of the functional domains within NR holoenzyme in equal measure. [source] The Cyclical Dynamics and Volatility of Australian Output and Employment,THE ECONOMIC RECORD, Issue 264 2008DAVID SHEPHERD In this paper, we examine the volatility of aggregate output and employment in Australia with the aid of a frequency filtering method. This analysis is compared with more traditional methods based on the examination of first differences in the logs of the raw data. We show that the application of univariate AR and bivariate VECM methods to the data results in a detrended series which is dominated by noise and gives break points which are not robust to alternative decomposition methods. When we apply a frequency filtered procedure we find that the detrended series is dominated by cyclical rather than noise variation. We find evidence of a sustained reduction in the cyclical volatility of both the gross domestic product and employment series in 1993,1994, not in 1984. We also find that there is a clear association between output volatility and employment volatility. [source] Vancomycin-resistant Enterococcus spp.: validation of susceptibility testing and in vitro activity of vancomycin, linezolid, tigecycline and daptomycinAPMIS, Issue 1 2010MATHIAS RATHE Rathe M, Kristensen L, Ellermann-Eriksen S, Thomsen MK, Schumacher H. Vancomycin-resistant Enterococcus spp.: validation of susceptibility testing and in vitro activity of vancomycin, linezolid, tigecycline and daptomycin. APMIS 2010; 118: 66,73. Vancomycin-resistant enterococci (VRE) have emerged to become a significant nosocomial pathogen. However, detection may be challenging and treatment possibilities are limited. Reports of resistance to linezolide, daptomycin and tigecycline underline the need for reliable susceptibility testing with respect to these compounds. We evaluated the in vitro activity of vancomycin, linezolid, daptomycin and tigecycline against a panel of VRE and vancomycin-susceptible enterococci by broth microdilution (BMD). Etest for determination of minimum inhibitory concentration of these four antibiotics and two disc diffusion assays for detecting VRE and for susceptibility testing against tigecycline and linezolid were evaluated. Before susceptibility testing, all isolates were classified by polymerase chain reaction as vanA or vanB gene positive or vanA/B gene negative. Linezolid, daptomycin and tigecycline had excellent in vitro activity towards all isolates. For daptomycin and tigecycline, the overall agreement between BMD and Etest was suboptimal. For both disc diffusion assays, use of current break points was inadequate to detect vancomycin resistance for isolates carrying the vanB gene. Inspection of the inhibition zone for a diffuse edge, as recommended, accurately predicted presence of the vanB gene. [source] | |||||||||||||||||||