bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cephalosporin MIC Distribution of Extended-Spectrum-β-Lactamase- and pAmpC-Producing
Escherichia coli
and
Klebsiella
Species
Authors: Kohner Peggy C. , Robberts Frans J. L. , Cockerill Franklin R. , Patel Robin 
Published: June 2009

ABSTRACT

The acquisition of β-lactamases in members of the
Enterobacteriaceae
family poses a challenge to antimicrobial susceptibility testing in the clinical laboratory. We correlated the distribution of the MICs for
Klebsiella
spp. and
Escherichia coli
with the presence of extended-spectrum β-lactamase (ESBL) and plasmid-mediated AmpC β-lactamase (pAmpC) genes. A total of 264 isolates were subjected to cefazolin, ceftriaxone, cefotaxime, ceftazidime, cefepime, and aztreonam agar dilution MIC determination; ESBL screening and confirmatory testing by the methods of the Clinical and Laboratory Standards Institute (CLSI); and for isolates for which the MICs of extended-spectrum cephalosporins were ≥1 μg/ml or the MICs of cefpodoxime were >4 μg/ml, PCR amplification and sequencing of the ESBL and pAmpC genes. PCR was positive for 73/81 isolates (45 isolates with an ESBL gene alone, 24 isolates with a pAmpC gene alone, with 4 isolates with both genes). Compared to PCR, confirmatory testing by the CLSI method yielded a sensitivity and a specificity of 98.0 and 96.3%, respectively; there were six false-positive results and one false-negative result. No distinction in the MIC distribution was apparent between isolates with the ESBL gene and isolates with the pAmpC gene. A substantial percentage of the isolates with PCR-confirmed ESBL and/or pAmpC genes fell within the current CLSI susceptible category. For a ceftazidime, ceftriaxone, or cefotaxime MIC of ≥2 μg/ml, a dichotomy existed between isolates with and without ESBL and pAmpC genes in most cases. This suggests that the presence of the ESBL and the pAmpC enzymes may yield similar MICs of extended-spectrum cephalosporins, many of which fall within the current nonresistant categories. Lowering of the current CLSI breakpoints for cephalosporins appears to be warranted.
Genes Related to Long Polar Fimbriae of Pathogenic
Escherichia coli
Strains as Reliable Markers To Identify Virulent Isolates
Authors: Torres Alfredo G. , Blanco Miguel , Valenzuela Patricio , Slater Terry M. , Patel Shilpa D. , Dahbi Ghizlane , López Cecilia , Barriga Ximena Fernández , Blanco Jesús E. , Gomes Tânia A. T. , Vidal Roberto , Blanco Jorge 
Published: June 2009

ABSTRACT

Lpf (stands for long polar fimbriae) is one of the few adhesive factors of enterohemorrhagic
Escherichia coli
O157:H7 associated with colonization of the intestine.
E. coli
O157:H7 strains possess two
lpf
loci encoding highly regulated fimbrial structures. Database analysis of the genes encoding the major fimbrial subunits demonstrated that they are present in commensal as well as pathogenic (both intestinal and extraintestinal)
E. coli
strains and in
Salmonella
strains and that the
lpfA1
and
lpfA2
genes are highly prevalent among LEE (locus of enterocyte effacement)-positive
E. coli
strains associated with severe and/or epidemic disease. Further DNA sequence analysis of the
lpfA1
and
lpfA2
genes from different attaching-and-effacing
E. coli
strains has led us to the identification of several polymorphisms and the classification of the major fimbrial subunits into distinct variants. Using collections of pathogenic
E. coli
isolates from Europe and Latin America, we demonstrated that the different
lpfA
types are associated with the presence of specific intimin (
eae
) adhesin variants and, most importantly, that they are found in specific
E. coli
pathotypes. Our results showed that the use of these fimbrial genes as markers, in combination with the different intimin types, resulted in a specific test for the identification of
E. coli
O157:H7, distinguishing it from other pathogenic
E. coli
strains.
Risk Factors for Campylobacteriosis: an Epidemiological Surveillance Study of Patients and Retail Poultry
Authors: Lindmark H. , Boqvist S. , Ljungström M. , Ågren P. , Björkholm B. , Engstrand L. 
Published: June 2009

ABSTRACT

Isolates from
Campylobacter jejuni-
infected patients were collected and fresh poultry meat from retail sources was sampled during the same time period and within the same geographical area. The patients were interviewed about exposure to known risk factors, and a significant correlation between the presence of a poultry subtype in patients and the consumption of fresh poultry meat was observed.
Mycobacterium tuberculosis
in Ontario, Canada: Insights from IS
6110
Restriction Fragment Length Polymorphism and Mycobacterial Interspersed Repetitive-Unit-Variable-Number Tandem-Repeat Genotyping
Authors: Alexander David C. , Guthrie Jennifer L. , Pyskir Daria , Maki Anne , Kurepina Natalia , Kreiswirth Barry N. , Chedore Pamela , Drews Steven J. , Jamieson Frances 
Published: June 2009

ABSTRACT

A collection of 1,308 clinical
Mycobacterium tuberculosis
isolates from Ontario, Canada, was genotyped by IS
6110
restriction fragment length polymorphism (RFLP) and mycobacterial interspersed repetitive-unit-variable-number tandem-repeat (MIRU-VNTR) analysis. RFLP or >12 MIRU-VNTR loci were necessary for resolution of Indo-Oceanic strains. The low clustering rate and high strain diversity indicate that, in Ontario, most tuberculosis results from reactivation of latent infections.
Prions Are Secreted in Milk from Clinically Normal Scrapie-Exposed Sheep
Authors: Maddison B. C. , Baker C. A. , Rees H. C. , Terry L. A. , Thorne L. , Bellworthy S. J. , Whitelam G. C. , Gough K. C. 
Published: June 2009

ABSTRACT

The potential spread of prion infectivity in secreta is a crucial concern for prion disease transmission. Here, serial protein misfolding cyclic amplification (sPMCA) allowed the detection of prions in milk from clinically affected animals as well as scrapie-exposed sheep at least 20 months before clinical onset of disease, irrespective of the immunohistochemical detection of protease-resistant PrP
Sc
within lymphoreticular and central nervous system tissues. These data indicate the secretion of prions within milk during the early stages of disease progression and a role for milk in prion transmission. Furthermore, the application of sPMCA to milk samples offers a noninvasive methodology to detect scrapie during preclinical/subclinical disease.
Combinations of the First and Next Generations of Human Immunodeficiency Virus (HIV) Fusion Inhibitors Exhibit a Highly Potent Synergistic Effect against Enfuvirtide- Sensitive and -Resistant HIV Type 1 Strains
Authors: Pan Chungen , Cai Lifeng , Lu Hong , Qi Zhi , Jiang Shibo 
Published: June 2009

ABSTRACT
T20 (generic name, enfuvirtide; brand name, Fuzeon) is a first-generation human immunodeficiency virus (HIV) fusion inhibitor approved for salvage therapy of HIV-infected patients refractory to current antiretroviral drugs. However, its clinical use is limited because of rapid emergence of T20-resistant viruses in T20-treated patients. Therefore, T1249 and T1144 are being developed as the second- and third-generation HIV fusion inhibitors, respectively, with improved efficacy and drug resistance profiles. Here, we found that combinations of T20 with T1249 and/or T1144 resulted in exceptionally potent synergism (combination index, <0.01) against HIV-1-mediated membrane fusion by 2 to 3 orders of magnitude in dose reduction. Highly potent synergistic antiviral efficacy was also achieved against infection by laboratory-adapted and primary HIV-1 strains, including T20-resistant variants. The mechanism underlying the synergistic effect could be attributed to the fact that T20, T1249, and T1144 all contain different functional domains and have different primary binding sites in gp41. As such, they may work cooperatively to inhibit gp41 six-helix bundle core formation, thereby suppressing virus-cell fusion. Therefore, these findings strongly imply that, rather than replacing T20, combining it with HIV fusion inhibitors of different generations might produce synergistic activity against both T20-sensitive and -resistant HIV-1 strains, suggesting a new therapeutic strategy for the treatment of HIV-1 infection/AIDS.
Reassortment between Avian H5N1 and Human H3N2 Influenza Viruses in Ferrets: a Public Health Risk Assessment
Authors: Jackson Sara , Van Hoeven Neal , Chen Li-Mei , Maines Taronna R. , Cox Nancy J. , Katz Jacqueline M. , Donis Ruben O. 
Published: June 2009

ABSTRACT
This study investigated whether transmissible H5 subtype human-avian reassortant viruses could be generated in vivo. To this end, ferrets were coinfected with recent avian H5N1 (A/Thailand/16/04) and human H3N2 (A/Wyoming/3/03) viruses. Genotype analyses of plaque-purified viruses from nasal secretions of coinfected ferrets revealed that approximately 9% of recovered viruses contained genes from both progenitor viruses. H5 and H3 subtype viruses, including reassortants, were found in airways extending toward and in the upper respiratory tract of ferrets. However, only parental H5N1 genotype viruses were found in lung tissue. Approximately 34% of the recovered reassortant viruses possessed the H5 hemagglutinin (HA) gene, with five unique H5 subtypes recovered. These H5 reassortants were selected for further studies to examine their growth and transmissibility characteristics. Five H5 viruses with representative reassortant genotypes showed reduced titers in nasal secretions of infected ferrets compared to the parental H5N1 virus. No transmission by direct contact between infected and naïve ferrets was observed. These studies indicate that reassortment between H5N1 avian influenza and H3N2 human viruses occurred readily in vivo and furthermore that reassortment between these two viral subtypes is likely to occur in ferret upper airways. Given the relatively high incidence of reassortant viruses from tissues of the ferret upper airway, it is reasonable to conclude that continued exposure of humans and animals to H5N1 alongside seasonal influenza viruses increases the risk of generating H5 subtype reassortant viruses that may be shed from upper airway secretions.
Nuclear Factor 90 Negatively Regulates Influenza Virus Replication by Interacting with Viral Nucleoprotein
Authors: Wang Pui , Song Wenjun , Mok Bobo Wing-Yee , Zhao Pengxi , Qin Kun , Lai Alexander , Smith Gavin J. D. , Zhang Jinxia , Lin Tianwei , Guan Yi , Chen Honglin 
Published: June 2009

ABSTRACTInteractions between host factors and the viral replication complex play important roles in host adaptation and regulation of influenza virus replication. A cellular protein, nuclear factor 90 (NF90), was copurified with H5N1 viral nucleoprotein (NP) from human cells in which NP was transiently expressed and identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis. In vitro coimmunoprecipitation of NF90 and NP coexpressed in HEK 293T cells or individually expressed in bacterial and HEK 293T cells, respectively, confirmed a direct interaction between NF90 and NP, independent of other subunits of the ribonucleoprotein complex. This interaction was prevented by a mutation, F412A, in the C-terminal region of the NP, indicating that the C-terminal of NP is required for NF90 binding. RNase V treatment did not prevent coprecipitation of NP and NF90, which demonstrates that the interaction is RNA binding independent. After small interfering RNA knockdown of NF90 expression in A549 and HeLa cells, viral polymerase complex activity and virus replication were significantly increased, suggesting that NF90 negatively affects viral replication. Both NP and NF90 colocalized in the nucleus of virus-infected cells during the early phase of infection, suggesting that the interaction between NF90 and NP is an early event in virus replication. Quantitative reverse transcription-PCR showed that NF90 downregulates both viral genome replication and mRNA transcription in infected cells. These results suggest that NF90 inhibits influenza virus replication during the early phase of infection through direct interaction with viral NP.
Time-Dependent Transformation of the Herpesvirus Tegument
Authors: Newcomb William W. , Brown Jay C. 
Published: June 2009

ABSTRACT
All herpesviruses have a layer of protein called the tegument that lies between the virion membrane and the capsid. The tegument consists of multiple, virus-encoded protein species that together can account for nearly half the total virus protein. To clarify the structure of the tegument and its attachment to the capsid, we used electron microscopy and protein analysis to examine the tegument of herpes simplex virus type 1 (HSV-1). Electron microscopic examination of intact virions revealed that whereas the tegument was asymmetrically distributed around the capsid in extracellular virions, it was symmetrically arranged in cell-associated virus. Examination of virions after treatment with nonionic detergent demonstrated that: (i) in extracellular virus the tegument was resistant to removal with Triton X-100 (TX-100), whereas it was lost nearly completely when cell-associated virus was treated in the same way; (ii) the tegument in TX-100-treated extracellular virions was asymmetrically distributed around the capsid as it is in unextracted virus; and (iii) in some images, tegument was seen to be linked to the capsid by short, regularly spaced connectors. Further analysis was carried out with extracellular virus harvested from cells at different times after infection. It was observed that while the amount of tegument present in virions was not affected by time of harvest, the amount remaining after TX-100 treatment increased markedly as the time of harvest was increased from 24 h to 64 h postinfection. The results support the view that HSV-1 virions undergo a time-dependent change in which the tegument is transformed from a state in which it is symmetrically organized around the capsid and extractable with TX-100 to a state where it is asymmetrically arranged and resistant to extraction.
Dynamics of Biologically Active Subpopulations of Influenza Virus: Plaque-Forming, Noninfectious Cell-Killing, and Defective Interfering Particles
Authors: Marcus Philip I. , Ngunjiri John M. , Sekellick Margaret J. 
Published: June 2009

ABSTRACTThe dynamic changes in the temporal appearance and quantity of a new class of influenza virus, noninfectious cell-killing particles (niCKP), were compared to defective interfering particles (DIP). After a single high-multiplicity passage in MDCK cells of an egg-derived stock that lacked detectable niCKP or DIP, both classes of particles appeared in large numbers (>5 × 108/ml), and the plaque-forming particle (PFP) titer dropped ∼60-fold. After two additional serial high-multiplicity passages the DIP remained relatively constant, the DIP/niCKP ratio reached 10:1, and the PFP had declined by about 10,000-fold. Together, the niCKP and DIP subpopulations constituted ca. 20% of the total hemagglutinating particle population in which these noninfectious biologically active particles (niBAP) were subsumed. DIP neither killed cells nor interfered with the cell-killing (apoptosis-inducing) activity of niCKP or PFP (infectious CKP), even though they blocked the replication of PFP. Relative to the UV-target of ∼13,600 nucleotides (nt) for inactivation of PFP, the UV target for niCKP was ∼2,400 nt, consistent with one of the polymerase subunit genes, and that for DIP was ∼350 nt, consistent with the small DI-RNA responsible for DIP-mediated interference. Thus, niCKP and DIP are viewed as distinct particles with a propensity to form during infection at high multiplicities. These conditions are postulated to cause aberrations in the temporally regulated replication of virus and its packaging, leading to the production of niBAP. DIP have been implicated in the virulence of influenza virus, but the role of niCKP is yet unknown.
Comparative study of inhibitory antibody derivatives towards thrombin activatable fibrinolysis inhibitor
Authors: Develter Jan , Dewilde Maarten , Gils Ann , Declerck Paul J. 
Published: June 2009

SummaryThrombin activatable fibrinolysis inhibitor (TAFI) attenuates fibrinolysis and is considered as an attractive drug target. We generated two different antibody fragments, an antigen-binding fragment (Fab) and a single-chain variable fragment (scFv), derived from three distinct monoclonal antibodies (MAs) that inhibit the activation of TAFI by the thrombin/thrombomodulin complex (T/TM) and plasmin (MA-T1C10 and MA-T94H3) or by T/TM alone (MA-T12D11). The Fabs were obtained by papain digestion of the purified Mas, whereas the scFvs were cloned and subsequently expressed in bacteria. All antibody fragments revealed similar or slightly decreased affinities compared to those of the respective Mas, except scFv-T94H3. In the presence of a 16-fold molar excess of all antibody fragments, activation of TAFI by T/TM was completely blocked. Furthermore, Fab and scFv-derivatives from MA-T1C10 and MA-T94H3 were capable of interfering with the plasmin-mediated activation of TAFI. Addition of 850 nM of MA, Fab or scFv to an in-vitro clot lysis assay caused a significant reduction of clot lysis time (except for scFv-T94H3) and this effect was comparable to that of potato tuber carboxypeptidase inhibitor, a well-known TAFIa inhibitor. Dose-response experiments with the antibody (derivatives) in clot lysis and chromogenic assay revealed that the inhibitory capacity of the Fabs was comparable to that of the Mas, whereas the scFvs had a more reduced potency. In conclusion, these highly specific TAFI inhibitors are interesting tools to further evaluate the concept of TAFI inhibition in various in-vitro and in-vivo models.
Hypercoagulability is independently associated with kynurenine pathway activation in dialysed uraemic patients
Authors: Pawlak Krystyna , Mysliwiec Michal , Pawlak Dariusz 
Published: June 2009

SummaryPatients with end-stage renal disease (ESRD) exhibit features of a hypercoagulable state, which may contribute to atherosclerosis. Kynurenines are the metabolites of tryptophan degradation in mammals. We examined the relationship between coagulation activation and kynurenines in 92 patients with ESRD on maintenance haemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) and 20 healthy controls. We measured the plasma levels of: tissue factor (TF), its pathway inhibitor (TFPI), the marker of coagulation activation – prothrombin fragments 1+2 (F1+2), kynurenine (KYN) and its metabolites: kynurenic (KYNA), anthranilic (AA) and quinolinic (QA) acids. The ratio of KYNA to KYN (kyna/kyn), AA to KYN (aa/kyn) and QA to KYN (qa/kyn), reflecting intensified activity of enzymes which converted KYN to its metabolites, were also determined. Measured coagulation parameters and kynurenines were significantly elevated in ESRD patients compared to controls. TF, TFPI and F1+2 were significantly associated with AA, aa/kyn, QA and qa/kyn ratio. Multiple regression analysis showed that fibrinogen (p<0.01) and above mentioned KYN metabolites (all p<0.05) were the independent variables significantly associated with increased F1+2 levels, reflecting hypercoagulability in ESRD patients. In conclusion, this study represents the first to investigate both the coagulation system and KYN pathway in ESRD patients. The coagulation was enhanced in dialysed uraemic patients compared with the healthy controls demonstrated by increased TF, TFPI and F1+2 levels. These changes were correlated with activation of the KYN pathway. Finally, fibrinogen and KYN metabolites are independently and significantly associated with the hypercoagulable state in uraemic patients on CAPD and HD treatment.
The in-vitro effects of E5555, a protease-activated receptor (PAR)-1 antagonist, on platelet biomarkers in healthy volunteers and patients with coronary artery disease
Authors: Kogushi Motoji , Dastros-Pitei Daniela , Flather Marcus , Bhatt Deepak L. , Serebruany Victor L. 
Published: June 2009

SummaryE5555 is a potent protease-activated receptor (PAR-1) antagonist targeting the G-coupled receptor and modulating thrombinplatelet-endothelial interactions. The drug is currently being tested in phase II trials in patients with coronary artery disease (CAD) and has potential antithrombotic and anti-inflammatory benefits.We investigated the in-vitro effects of E5555 on platelet function beyond PAR-1 blockade in healthy volunteers and CAD patients treated with aspirin (ASA) with or without clopidogrel. Conventional aggregation induced by 5 µM ADP, 1 µg/ml collagen, 10 µM TRAP, whole blood aggregation with 1 µg/ml collagen, and expression of 14 intact, and TRAP-stimulated receptors by flow cytometry were utilised to assess platelet activity after preincubation with escalating concentrations of E5555 (20 ng/ml, 50 ng/ml, and 100 ng/ml) in healthy volunteers, CAD patients treated with ASA, and CAD patients treated with ASA and clopidogrel combination (n=10, for each group). E5555 inhibited a number of platelet biomarkers. Platelet inhibition was usually moderate, present already at 20 ng/ml, and was not seemingly dose-dependent without TRAP stimulation. E5555 caused 10–15% inhibition of ADP- and collagen-induced platelet aggregation in plasma, but not in whole blood.TRAP-induced aggregation was inhibited almost completely. PECAM-1, GP IIb/IIIa antigen, and activity with PAC-1, GPIb, thrombospondin, vitronectin receptor expression, and formation of platelet-monocyte aggregates were also significantly reduced by E5555.TRAP stimulation caused dose-dependent effects between 20 and 50 ng/ml E5555 doses. P-selectin, LAMP-1, LAMP, and CD40-ligand were not affected by E5555. In conclusion, E5555 in vitro moderately but significantly inhibits platelet activity beyond PAR-1 blockade. Antiplatelet potency of ASA alone, and the combination of ASA and clopidogrel may be enhanced by E5555 providing rationale for their synergistic use. Selective blockade of platelet receptors suggests unique antiplatelet properties of E5555 as a potential addition to current antithrombotic regimens.
Pairing and recombination features during meiosis in Cebus paraguayanus (Primates: Platyrrhini)
Authors: Garcia-Cruz Raquel , Robles Pedro , Steinberg Eliana R , Camats Nuria , Brieño Miguel A , Garcia-Caldés Montserrat , Mudry Marta D 
Published: June 2009

AbstractBackgroundAmong neotropical Primates, the Cai monkeyCebus paraguayanus(CPA) presents long, conserved chromosome syntenies with the human karyotype (HSA) as well as numerous C+ blocks in different chromosome pairs.In this study, immunofluorescence (IF) against two proteins of the Synaptonemal Complex (SC), namely REC8 and SYCP1, two recombination protein markers (RPA and MLH1), and one protein involved in the pachytene checkpoint machinery (BRCA1) was performed in CPA spermatocytes in order to analyze chromosome meiotic behavior in detail.ResultsAlthough in the vast majority of pachytene cells all autosomes were paired and synapsed, in a small number of nuclei the heterochromatic C-positive terminal region of bivalent 11 remained unpaired. The analysis of 75 CPA cells at pachytene revealed a mean of 43.22 MLH1 foci per nucleus and 1.07 MLH1 foci in each CPA bivalent 11, always positioned in the region homologous to HSA chromosome 21.ConclusionOur results suggest that C blocks undergo delayed pairing and synapsis, although they do not interfere with the general progress of pairing and synapsis.