bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mutational Analysis of Class A and Class B Penicillin-Binding Proteins in
Streptococcus gordonii
Authors: Haenni Marisa , Majcherczyk Paul A. , Barblan Jean-Luc , Moreillon Philippe 
Published: November 2006

ABSTRACT

High-molecular-weight (HMW) penicillin-binding proteins (PBPs) are divided into class A and class B PBPs, which are bifunctional transpeptidases/transglycosylases and monofunctional transpeptidases, respectively. We determined the sequences for the HMW PBP genes of
Streptococcus gordonii
, a gingivo-dental commensal related to
Streptococcus pneumoniae
. Five HMW PBPs were identified, including three class A (PBPs 1A, 1B, and 2A) and two class B (PBPs 2B and 2X) PBPs, by homology with those of
S. pneumoniae
and by radiolabeling with [
3
H]penicillin. Single and double deletions of each of them were achieved by allelic replacement. All could be deleted, except for PBP 2X, which was essential. Morphological alterations occurred after deletion of PBP 1A (lozenge shape), PBP 2A (separation defect and chaining), and PBP 2B (aberrant septation and premature lysis) but not PBP 1B. The muropeptide cross-link patterns remained similar in all strains, indicating that cross-linkage for one missing PBP could be replaced by others. However, PBP 1A mutants presented shorter glycan chains (by 30%) and a relative decrease (25%) in one monomer stem peptide. Growth rate and viability under aeration, hyperosmolarity, and penicillin exposure were affected primarily in PBP 2B-deleted mutants. In contrast, chain-forming PBP 2A-deleted mutants withstood better aeration, probably because they formed clusters that impaired oxygen diffusion. Double deletion could be generated with any PBP combination and resulted in more-altered mutants. Thus, single deletion of four of the five HMW genes had a detectable effect on the bacterial morphology and/or physiology, and only PBP 1B seemed redundant a priori.
High Prevalence of the K65R Mutation in Human Immunodeficiency Virus Type 1 Subtype C Isolates from Infected Patients in Botswana Treated with Didanosine-Based Regimens
Authors: Doualla-Bell Florence , Avalos Ava , Brenner Bluma , Gaolathe Tendani , Mine Madisa , Gaseitsiwe Simani , Oliveira Maureen , Moisi Daniella , Ndwapi Ndwapi , Moffat Howard , Essex Max , Wainberg Mark A. 
Published: November 2006

ABSTRACTWe analyzed the reverse transcriptase genotypes of human immunodeficiency virus type 1 subtype C viruses isolated from 23 patients in Botswana treated with didanosine-based regimens. The K65R mutation was selected either alone or together with the Q151M, S68G, or F116Y substitution in viruses from seven such individuals. The results of in vitro passage experiments were consistent with an apparent increased propensity of subtype C viruses to develop the K65R substitution.
In Vitro Activities of the Novel Oxazolidinones DA-7867 and DA-7157 against Rapidly and Slowly Growing Mycobacteria
Authors: Vera-Cabrera Lucio , Brown-Elliott Barbara A. , Wallace Richard J. , Ocampo-Candiani Jorge , Welsh Oliverio , Choi Sung Hak , Molina-Torres Carmen A. 
Published: November 2006

ABSTRACT

DA-7867 and DA-7157 are oxazolidinones active against pathogenic aerobic actinomycetes including
Nocardia
spp. and
Mycobacterium tuberculosis
. However, the activity of these drugs against nontuberculous mycobacterium (NTM) species is not known. In this work, we compared the susceptibilities of 122 clinical isolates and 29 reference species of both rapidly growing and slowly growing mycobacteria to linezolid, DA-7867, and DA-7157 by the broth microdilution method. The MICs for 50 and 90% of the strains tested (MIC
50
s and MIC
90
s, respectively) of DA-7867 and DA-7157 were lower than those of linezolid. In all of the cases, a MIC
90
of <8 μg/ml was observed for all of the species tested in both groups of NTM. For
M. kansasii
and
M. marinum
isolates, the MIC
90
s of both DA-7867 and DA-7157 were less than 0.5 μg/ml. These results demonstrate the potential of these compounds to treat NTM infections.
In Vitro Inhibition of
Toxoplasma gondii
by Four New Derivatives of Artemisinin
Authors: Jones-Brando Lorraine , D'Angelo John , Posner Gary H. , Yolken Robert 
Published: November 2006

ABSTRACT

Toxoplasmosis, caused by the protozoan
Toxoplasma gondii
, is medically important and distributed worldwide. Currently available medications are limited in terms of efficacy and side effects. We synthesized novel, nonacetal, hydrolytically stable derivatives of artemisinin and showed that they inhibit the replication of
Toxoplasma gondii
in cell culture.
Molecular Characteristics and In Vitro Susceptibility to Antimicrobial Agents, Including the Des-Fluoro(6) Quinolone DX-619, of Panton-Valentine Leucocidin-Positive Methicillin-Resistant
Staphylococcus aureus
Isolates from the Community and Hospitals
Authors: Yamamoto Tatsuo , Dohmae Soshi , Saito Kohei , Otsuka Taketo , Takano Tomomi , Chiba Megumi , Fujikawa Katsuko , Tanaka Mayumi 
Published: November 2006

ABSTRACT

Highly virulent, community-acquired methicillin-resistant
Staphylococcus aureus
(MRSA) strains with Panton-Valentine leucocidin (PVL) genes have been found increasingly worldwide. Among a total of 2,101 MRSA strains isolated from patients in hospitals in Japan, two were positive for PVL genes. One strain was identified as a community-acquired MRSA strain with genotype sequence type 30 (ST30) and
spa
(staphylococcal protein A gene) type 19 from Japan and was resistant only to β-lactam antimicrobial agents. The other strain was closely related to PVL
+
multidrug-resistant, hospital-acquired MRSA strains (ST30,
spa
type 43) derived from nosocomial outbreaks in the 1980s to 1990s in Japan but with a divergent sequence type, ST765 (a single-locus variant of ST30). Twenty-two PVL
+
MRSA strains, including those from Japan and those from other countries with various sequence types (ST1, ST8, ST30, ST59, and ST80) and genotypes, were examined for susceptibility to 31 antimicrobial agents. Among the agents, DX-619, a des-fluoro(6) quinolone, showed the greatest activity, followed by rifampin and sitafloxacin, a fluoroquinolone. The data suggest that DX-619 exhibits a superior activity against PVL
+
MRSA strains with various virulence genetic traits from the community as well as from hospitals.
TherapeuticChlamydophila abortusandC. pecorumVaccination Transiently Reduces Bovine Mastitis Associated withChlamydophilaInfection
Authors: Biesenkamp-Uhe Carolin , Li Yihang , Hehnen Hans-Robert , Sachse Konrad , Kaltenboeck Bernhard 
Published: November 2006

ABSTRACTInfections withChlamydophila abortusandC. pecorumare highly prevalent in cattle and have been associated with bovine mastitis. A prospective cohort study was conducted with a herd of 140 Holstein dairy cows to investigate the influence ofChlamydophilainfection on subclinical inflammation of the bovine mammary gland as characterized by somatic cell numbers in milk. PCR detection ofC. abortusand low serum antibody levels againstChlamydophilaspp. were significantly associated with subclinical mastitis. To examine the effect of the infection by response modification, immune perturbation was done by two subcutaneous administrations of an experimental vaccine preparation of inactivatedC. abortusandC. pecorumelementary bodies. Vaccination againstChlamydophilahighly significantly decreased milk somatic cell numbers, thus reducing bovine mastitis, and increased antibody levels againstChlamydophilabut did not eliminate shedding ofC. abortusin milk as detected by PCR. The protective effect peaked at 11 weeks after vaccination and lasted for a total of 14 weeks. Vaccination with theChlamydophilavaccine, a mock vaccine, or a combination vaccine against bovine viral diseases highly significantly increasedC. abortusshedding in milk for 1 week, presumably mediated by the vaccine adjuvant. In summary, this study shows an etiological involvement of the widespreadChlamydophilainfections in bovine mastitis, a herd disease of critical importance for the dairy industry. Furthermore, this investigation shows the potential for temporary improvement of chlamydial disease by therapeutic vaccination.Chlamydophilavaccination of cattle might serve as a testing ground for vaccines against human chlamydial infections.
Growth Condition-Dependent Esp Expression by
Enterococcus faecium
Affects Initial Adherence and Biofilm Formation
Authors: Van Wamel Willem J. B. , Hendrickx Antoni P. A. , Bonten Marc J. M. , Top Janetta , Posthuma George , Willems Rob J. L. 
Published: November 2006

ABSTRACT

A genetic subpopulation of
Enterococcus faecium
, called clonal complex 17 (CC-17), is strongly associated with hospital outbreaks and invasive infections. Most CC-17 strains contain a putative pathogenicity island encoding the
E. faecium
variant of enterococcal surface protein (Esp). Western blotting, flow cytometric analyses, and electron microscopy showed that Esp is expressed and exposed on the surface of
E. faecium
, though Esp expression and surface exposure are highly varied among different strains. Furthermore, Esp expression depends on growth conditions like temperature and anaerobioses. When grown at 37°C, five of six
esp
-positive
E. faecium
strains showed significantly increased levels of surface-exposed Esp compared to bacteria grown at 21°C, which was confirmed at the transcriptional level by real-time PCR. In addition, a significant increase in surface-exposed Esp was found in half of these strains when grown at 37°C under anaerobic conditions compared to the level in bacteria grown under aerobic conditions. Finally, amounts of surface-exposed Esp correlated with initial adherence to polystyrene (
R
2
= 0.7146) and biofilm formation (
R
2
= 0.7535). Polystyrene adherence was competitively inhibited by soluble recombinant N-terminal Esp. This study demonstrates that Esp expression on the surface of
E. faecium
(i) varies consistently between strains, (ii) is growth condition dependent, and (iii) is quantitatively correlated with initial adherence and biofilm formation. These data indicate that
E. faecium
senses and responds to changing environmental conditions, which might play a role in the early stages of infection when bacteria transit from oxygen-rich conditions at room temperature to anaerobic conditions at body temperature. In addition, variation of surface exposure may explain the contrasting findings reported on the role of Esp in biofilm formation.
ActA Is Required for Crossing of the Fetoplacental Barrier by
Listeria monocytogenes
Authors: Le Monnier Alban , Autret Nicolas , Join-Lambert Olivier F. , Jaubert Francis , Charbit Alain , Berche Patrick , Kayal Samer 
Published: November 2006

ABSTRACT

The facultative intracellular bacterial pathogen
Listeria monocytogenes
induces severe fetal infection during pregnancy. Little is known about the molecular mechanisms allowing the maternofetal transmission of bacteria. In this work, we studied fetoplacental invasion by infecting mice with various mutants lacking virulence factors involved in the intracellular life cycle of
L. monocytogenes
. We found that the placenta was highly susceptible to bacteria, including avirulent bacteria, such as an
L. monocytogenes
mutant with an
hly
deletion (ΔLLO) and a nonpathogenic species,
Listeria innocua
, suggesting that permissive trophoblastic cells, trapping bacteria, provide a protective niche for bacterial survival. The ΔLLO mutant, which is unable to escape the phagosomal compartment of infected cells, failed to grow in the trophoblast tissue and to invade the fetus. Mutant bacteria with
inlA
and
inlB
deletion (ΔInlAB) grew in the placenta and fetus as well as did the wild-type virulent stain (EGDwt), indicating that in the murine model, internalins A and B are not involved in fetoplacental invasion by
L. monocytogenes
. Pregnant mice were then infected with an
actA
deletion (ΔActA) strain, a virulence-attenuated mutant that is unable to polymerize actin and to spread from cell to cell. With the ΔActA mutant, fetal infection occurs, but with a significant delay and restriction, and it requires a placental bacterial load 2 log units higher than that for the wild-type virulent strain. Definitive evidence for the role of ActA was provided by showing that a
actA
-complemented ΔActA mutant was restored in its capacity to invade fetuses. ActA-mediated cell-to-cell spreading plays a major role in the vertical transmission of
L. monocytogenes
to the fetus in the murine model.
Galectin-3 Expression Is Associated with Tumor Progression and Pattern of Sun Exposure in Melanoma
Authors: Prieto Victor G. , Mourad-Zeidan Alexandra A. , Melnikova Vladislava , Johnson Marcella M. , Lopez Adriana , Diwan A. Hafeez , Lazar Alexander J.F. , Shen Steven S. , Zhang Peter S. , Reed Jon A. , Gershenwald Jeffrey E. , Raz Avraham , Bar-Eli Menashe 
Published: November 2006

Abstract
Purpose: Most studies accept a multistep pathogenic process in melanoma that may include the phases of benign nevi and dysplastic nevi, melanoma, and metastatic melanoma. Dysregulation of cellular proliferation and apoptosis is probably involved in melanoma progression and response to therapy. We have studied the expression of galectin-3, a β-galactoside-binding protein involved in apoptosis, angiogenesis, and cell proliferation, in a large series of melanocytic lesions, and correlated the expression with clinical and histologic features.
Experimental Design: Tissue microarray blocks of 94 melanocytic lesions were semiquantitatively evaluated by immunohistochemistry for the cytoplasmic or nuclear expression of galectin-3.
Results: Primary and metastatic melanomas expressed galectin-3 at a significantly higher level than nevi in both cytoplasm and nuclei (P &lt; 0.0073). There was a significant association between anatomic source (as indirect indication of level of sun-exposure) and cytoplasmic and nuclear expression. Lymph node and visceral metastases had a higher level of expression than s.c. lesions (P &lt; 0.004). Interestingly, there was an almost significant finding of worse survival in those patients with lesions showing higher levels of cytoplasmic than nuclear galectin-3 expression (log-rank test, P = 0.06).
Conclusions: Melanocytes accumulate galectin-3 with tumor progression, particularly in the nucleus. The strong association of cytoplasmic and nuclear expression in lesions of sun-exposed areas suggests an involvement of UV light in activation of galectin-3.
A Phase I Study of OncoVEXGM-CSF, a Second-Generation Oncolytic Herpes Simplex Virus Expressing Granulocyte Macrophage Colony-Stimulating Factor
Authors: Hu Jennifer C.C. , Coffin Robert S. , Davis Ceri J. , Graham Nicola J. , Groves Natasha , Guest Peter J. , Harrington Kevin J. , James Nicholas D. , Love Colin A. , McNeish Iain , Medley Louise C. , Michael Agnieszka , Nutting Christopher M. , Pandha Hardev S. , Shorrock Claire A. , Simpson Julie , Steiner Jan , Steven Neil M. , Wright Dennis , Coombes R. Charles 
Published: November 2006

Abstract
Purpose: To conduct a phase I clinical trial with a second-generation oncolytic herpes simplex virus (HSV) expressing granulocyte macrophage colony-stimulating factor (Onco VEXGM-CSF) to determine the safety profile of the virus, look for evidence of biological activity, and identify a dosing schedule for later studies.
Experimental Design: The virus was administered by intratumoral injection in patients with cutaneous or s.c. deposits of breast, head and neck and gastrointestinal cancers, and malignant melanoma who had failed prior therapy. Thirteen patients were in a single-dose group, where doses of 106, 107, and 108 plaque-forming units (pfu)/mL were tested, and 17 patients were in a multidose group testing a number of dose regimens.
Results: The virus was generally well tolerated with local inflammation, erythema, and febrile responses being the main side effects. The local reaction to injection was dose limiting in HSV-seronegative patients at 107 pfu/mL. The multidosing phase thus tested seroconverting HSV-seronegative patients with 106 pfu/mL followed by multiple higher doses (up to 108 pfu/mL), which was well tolerated by all patients. Biological activity (virus replication, local reactions, granulocyte macrophage colony-stimulating factor expression, and HSV antigen-associated tumor necrosis), was observed. The duration of local reactions and virus replication suggested that dosing every 2 to 3 weeks was appropriate. Nineteen of 26 patient posttreatment biopsies contained residual tumor of which 14 showed tumor necrosis, which in some cases was extensive, or apoptosis. In all cases, areas of necrosis also strongly stained for HSV. The overall responses to treatment were that three patients had stable disease, six patients had tumors flattened (injected and/or uninjected lesions), and four patients showed inflammation of uninjected as well as the injected tumor, which, in nearly all cases, became inflamed.
Conclusions: Onco VEXGM-CSF is well tolerated and can be safely administered using the multidosing protocol described. Evidence of an antitumor effect was seen.
Enhanced RASGEF1A Expression Is Involved in the Growth and Migration of Intrahepatic Cholangiocarcinoma
Authors: Ura Katsuaki , Obama Kazutaka , Satoh Seiji , Sakai Yoshiharu , Nakamura Yusuke , Furukawa Yoichi 
Published: November 2006

Abstract
Purpose and Experimental Design: To identify novel molecular targets for the treatment of intrahepatic cholangiocarcinoma (ICC), the second most common type of primary hepatobiliary cancer, we earlier analyzed genome-wide expression profiles of genes in 25 ICCs. Among the genes whose expression levels were commonly elevated in the tumors, we identified a novel gene termed RASGEF1A that encodes a putative Ras guanine nucleotide exchange factor domain-containing protein.
Results: We showed in this article that RASGEF1A protein has a guanine nucleotide exchange activity to K-RAS, H-RAS, and N-RAS proteins in vitro. Consistently, exogenous RASGEF1A expression increased the activity of Ras. In addition, suppression of RASGEF1A by small interfering RNA retarded the growth of cholangiocarcinoma cells. Interestingly, COS7 cells expressing exogenous RASGEF1A showed enhanced cellular motility in Transwell and wound-healing assays.
Conclusions: These data suggest that elevated expression of RASGEF1A may play an essential role for proliferation and progression of ICC. Our data indicate that RASGEF1A may be a promising therapeutic target for the majority of ICCs.
Frequent Epigenetic Inactivation of Spleen Tyrosine Kinase Gene in Human Hepatocellular Carcinoma
Authors: Yuan Yunfei , Wang Jianping , Li Jinqing , Wang Li , Li Meixiang , Yang Zuli , Zhang Changqing , Dai Jia Le 
Published: November 2006

Abstract
Purpose: The aim of present study was to investigate the methylation and expression status of spleen tyrosine kinase (SYK) in human hepatocellular carcinoma (HCC) and to evaluate this information for its ability to predict disease prognosis. E-cadherin and TIMP-3 methylation was also analyzed here as control because both were associated with poor prognosis in some types of tumors.
Experimental Design: We analyzed the methylation status of SYK, E-cadherin, and TIMP-3 in 124 cases of HCC and assessed the correlation of such methylations with clinicopathologic variables and prognosis after tumor resection.
Results: We found that SYK, E-cadherin, and TIMP-3 genes were methylated in 27%, 27%, and 42% of HCC neoplastic tissues, respectively. The loss of SYK mRNA or Syk protein expression was highly correlated with SYK gene methylation. The patients with methylated SYK in neoplastic tissues had a significantly lower overall survival rate after hepatectomy than those with unmethylated SYK. No significant difference in overall survival rates, however, was found between groups of patients with methylated and unmethylated E-cadherin or TIMP-3. Patients with negative Syk protein expression had a significantly lower overall survival rate than those with positive Syk protein expression. Multivariate analyses indicated that factors affecting overall survival were tumor-node-metastasis stage, Child-Pugh classification, SYK methylation, or Syk protein status.
Conclusions: Our results indicate that SYK methylation and loss of Syk expression in HCC neoplastic tissues are independent biomarkers of poor patient outcome and that determination of SYK methylation or Syk expression status may offer guidance for selecting appropriate treatments.
Vascular Endothelial Growth Factor Blockade Reduces Intratumoral Regulatory T Cells and Enhances the Efficacy of a GM-CSF–Secreting Cancer Immunotherapy
Authors: Li Betty , Lalani Alshad S. , Harding Thomas C. , Luan Bo , Koprivnikar Kathryn , Huan Tu Guang , Prell Rodney , VanRoey Melinda J. , Simmons Andrew D. , Jooss Karin 
Published: November 2006

Abstract
Purpose: The purpose of the present study was to evaluate granulocyte macrophage colony-stimulating factor (GM-CSF)–secreting tumor cell immunotherapy in combination with vascular endothelial growth factor (VEGF) blockage in preclinical models.
Experimental Design: Survival and immune response were monitored in the B16 melanoma and the CT26 colon carcinoma models. VEGF blockade was achieved by using a recombinant adeno-associated virus vector expressing a soluble VEGF receptor consisting of selected domains of the VEGF receptors 1 and 2 (termed sVEGFR1/R2). Dendritic cell and tumor infiltrating lymphocyte activation status and numbers were evaluated by fluorescence-activated cell sorting analysis. Regulatory T cells were quantified by their CD4+CD25hi and CD4+FoxP3+ phenotype.
Results: The present study established that GM-CSF–secreting tumor cell immunotherapy with VEGF blockade significantly prolonged the survival of tumor-bearing mice. Enhanced anti-tumor protection correlated with an increased number of activated CD4+ and CD8+ tumor-infiltrating T cells and a pronounced decrease in the number of suppressive regulatory T cells residing in the tumor. Conversely, overexpression of VEGF from tumors resulted in elevated numbers of regulatory T cells in the tumor, suggesting a novel mechanism of VEGF-mediated immune suppression at the tumor site.
Conclusion: GM-CSF–secreting cancer immunotherapy and VEGF blockade increases the i.t. ratio of effector to regulatory T cells to provide enhanced antitumor responses. This therapeutic combination may prove to be an effective strategy for the treatment of patients with cancer.