bluuebunny/crossref_metadata_2025_split huggingface dataset:
In Vivo
Activities of Ceftolozane, a New Cephalosporin, with and without Tazobactam against Pseudomonas aeruginosa and Enterobacteriaceae, Including Strains with Extended-Spectrum β-Lactamases, in the Thighs of Neutropenic Mice
Authors: Craig W. A. , Andes D. R. 
Published: December 2012

ABSTRACT

Ceftolozane is a new cephalosporin with potent activity against
Pseudomonas aeruginosa
and
Enterobacteriaceae
. A neutropenic murine thigh infection model was used to determine which pharmacokinetic/pharmacodynamic index and magnitude drives the efficacy of ceftolozane with Gram-negative bacilli, to compare the rates of
in vivo
killing of
P. aeruginosa
by ceftolozane and ceftazidime, and to determine the impact of different ratios of ceftolozane plus tazobactam on
Enterobacteriaceae
containing extended-spectrum β-lactamases (ESBLs). Neutropenic mice had 10
6.2-7.1
CFU/thigh when treated with ceftolozane for 24 h with (i) various doses (3.12 to 1,600 mg/kg) and dosage intervals (3, 6, 12, and 24 h) against two
Enterobacteriaceae
strains, (ii) 0.39 to 800 mg/kg every 6 h for four
Enterobacteriaceae
and four
P. aeruginosa
strains, and (iii) 400 or 800 mg/kg with 2:1. 4:1, and 8:1 ratios of tazobactam against five
Enterobacteriaceae
strains with ESBLs. The pharmacokinetics of ceftolozane at 25, 100, and 400 mg/kg were linear with peak/dose values of 1.0 to 1.4 and half-lives of 12 to 14 min. T>MIC was the primary index driving efficacy. For stasis (1 log kill), T>MIC was 26.3% ± 2.1% (31.6% ± 1.6%) for wild-type
Enterobacteriaceae
, 31.1% ± 4.9% (34.8% ± 4.4%) for
Enterobacteriaceae
with ESBLs, and 24.0% ± 3.3% (31.5% ± 3.9%) for
P. aeruginosa
. At 200 mg/kg every 3 h, the rate of
in vivo
killing of
P. aeruginosa
was faster with ceftolozane than with ceftazidime (−0.34 to −0.41 log
10
CFU/thigh/h versus −0.21 to −0.24 log
10
CFU/thigh/h). The 2:1 ratio of ceftolozane with tazobactam was the most potent combination studied. The T>MIC required for ceftolozane is less than with other cephalosporins and may be due to more rapid killing.
Cationic Antimicrobial Peptide LL-37 Is Effective against both Extra- and Intracellular Staphylococcus aureus
Authors: Noore Jabeen , Noore Adly , Li Bingyun 
Published: December 2012

ABSTRACT

The increasing resistance of bacteria to conventional antibiotics and the challenges posed by intracellular bacteria, which may be responsible for chronic and recurrent infections, have driven the need for advanced antimicrobial drugs for effective elimination of both extra- and intracellular pathogens. The purpose of this study was to determine the killing efficacy of cationic antimicrobial peptide LL-37 compared to conventional antibiotics against extra- and intracellular
Staphylococcus aureus
. Bacterial killing assays and an infection model of osteoblasts and
S. aureus
were studied to determine the bacterial killing efficacy of LL-37 and conventional antibiotics against extra- and intracellular
S. aureus
. We found that LL-37 was effective in killing extracellular
S. aureus
at nanomolar concentrations, while lactoferricin B was effective at micromolar concentrations and doxycycline and cefazolin at millimolar concentrations. LL-37 was surprisingly more effective in killing the clinical strain than in killing an ATCC strain of
S. aureus
. Moreover, LL-37 was superior to conventional antibiotics in eliminating intracellular
S. aureus
. The kinetic studies further revealed that LL-37 was fast in eliminating both extra- and intracellular
S. aureus
. Therefore, LL-37 was shown to be very potent and prompt in eliminating both extra- and intracellular
S. aureus
and was more effective in killing extra- and intracellular
S. aureus
than commonly used conventional antibiotics. LL-37 could potentially be used to treat chronic and recurrent infections due to its effectiveness in eliminating not only extracellular but also intracellular pathogens.
Pharmacokinetics and Pharmacodynamics of ASP2151, a Helicase-Primase Inhibitor, in a Murine Model of Herpes Simplex Virus Infection
Authors: Katsumata Kiyomitsu , Chono Koji , Kato Kota , Ohtsu Yoshiaki , Takakura Shoji , Kontani Toru , Suzuki Hiroshi 
Published: December 2012

ABSTRACT

ASP2151 (amenamevir) is a helicase-primase inhibitor against herpes simplex virus 1 (HSV-1), HSV-2, and varicella zoster virus. Here, to determine and analyze the correlation between the pharmacodynamic (PD) and pharmacokinetic (PK) parameters of ASP2151, we examined the PD profile of ASP2151 using
in vitro
plaque reduction assay and a murine model of HSV-1 infection. ASP2151 inhibited the
in vitro
replication of HSV-1 with a mean 50% effective concentration (EC
50
) of 14 ng/ml. In the cutaneously HSV-1-infected mouse model, ASP2151 dose dependently suppressed intradermal HSV-1 growth, with the effect reaching a plateau at a dose of 30 mg/kg of body weight/day. The dose fractionation study showed that intradermal HSV-1 titers were below the detection limit in mice treated with ASP2151 at 100 mg/kg/day divided into two daily doses and at 30 or 100 mg/kg/day divided into three daily doses. The intradermal HSV-1 titer correlated with the maximum concentration of drug in serum (
C
max
), the area under the concentration-time curve over 24 h (AUC
24h
), and the time during which the concentration of ASP2151 in plasma was above 100 ng/ml (
T
>100
). The continuous infusion of ASP2151 effectively decreased intradermal HSV-1 titers below the limit of detection in mice in which the ASP2151 concentration in plasma reached 79 to 145 ng/ml. Our findings suggest that the antiviral efficacy of ASP2151 is most closely associated with the PK parameter
T
>100
in HSV-1-infected mice. Based on these results, we propose that a plasma ASP2151 concentration exceeding 100 ng/ml for 21 to 24 h per day provides the maximum efficacy in HSV-1-infected mice.
Coordinated Roles of Pregnane X Receptor and Constitutive Androstane Receptor in Autoinduction of Voriconazole Metabolism in Mice
Authors: Ohbuchi Masato , Yoshinari Kouichi , Kaneko Hayato , Matsumoto Satoru , Inoue Akiko , Kawamura Akio , Usui Takashi , Yamazoe Yasushi 
Published: December 2012

ABSTRACT

The antifungal efficacy of voriconazole (VRC) differs among host species, with potent efficacy in humans but less in rodents. We investigated the possible involvement of pregnane X receptor (PXR) and constitutive androstane receptor (CAR) in the species-specific efficacy of VRC through pharmacokinetic analyses using genetically modified mice and primary human hepatocytes. VRC (30 mg/kg) was orally administered to wild-type,
Pxr
-null,
Car
-null, and
Pxr
- and
Car
-null (
Pxr
/
Car
-null) mice for 7 days. Hepatic VRC metabolism was significantly increased by VRC administration, and the elimination rates of plasma VRC were much higher on day 7 than on day 1 in wild-type mice. This autoinduction was also observed in
Pxr
-null and
Car
-null mice but not in
Pxr
/
Car
-null mice, suggesting coordinated roles of PXR and CAR in the autoinduction of VRC metabolism in mice. Hepatic
Cyp3a11
mRNA levels were increased by VRC administration, hepatic metabolic activities for VRC were correlated with CYP3A activities, and the induced VRC metabolism was inhibited by ketoconazole (a CYP3A inhibitor). In primary human hepatocytes, VRC barely increased mRNA levels of
CYP3A4
and
CYP2B6
(human PXR/CAR target genes) at its therapeutic concentrations. In conclusion, these results suggest that VRC is metabolized mainly by CYP3A11 in mouse livers and that PXR- and CAR-mediated CYP3A11 induction, namely, autoinduction of VRC metabolism, is a primary reason for the ineffectiveness of VRC in mice. A limited ability of VRC to activate human PXR/CAR at its clinical concentration might explain the VRC efficacy in humans. Therefore, the ability to activate PXR/CAR might determine the VRC efficacy in different mammalian species.
Mutational and Transcriptomic Changes Involved in the Development of Macrolide Resistance in Campylobacter jejuni
Authors: Hao Haihong , Yuan Zonghui , Shen Zhangqi , Han Jing , Sahin Orhan , Liu Peng , Zhang Qijing 
Published: December 2012

ABSTRACT

Macrolide antibiotics are important for clinical treatment of infections caused by
Campylobacter jejuni
. Development of resistance to this class of antibiotics in
Campylobacter
is a complex process, and the dynamic molecular changes involved in this process remain poorly defined. Multiple lineages of macrolide-resistant mutants were selected by stepwise exposure of
C. jejuni
to escalating doses of erythromycin or tylosin. Mutations in target genes were determined by DNA sequencing, and the dynamic changes in the expression of antibiotic efflux transporters and the transcriptome of
C. jejuni
were examined by real-time reverse transcription-PCR, immunoblotting, and DNA microarray analysis. Multiple types of mutations in ribosomal proteins L4 and L22 occurred early during stepwise selection. On the contrary, the mutations in the 23S rRNA gene, mediating high resistance to macrolides, were observed only in the late-stage mutants. Upregulation of antibiotic efflux genes was observed in the intermediately resistant mutants, and the magnitude of upregulation declined with the occurrence of mutations in the 23S rRNA gene. DNA microarray analysis revealed the differential expression of 265 genes, most of which occurred in the intermediate mutant, including the upregulation of genes encoding ribosomal proteins and the downregulation of genes involved in energy metabolism and motility. These results indicate (i) that mutations in L4 and L22 along with temporal overexpression of antibiotic efflux genes precede and may facilitate the development of high-level macrolide resistance and (ii) that the development of macrolide resistance affects the pathways important for physiology and metabolism in
C. jejuni
, providing an explanation for the reduced fitness of macrolide-resistant
Campylobacter
.
Azole Affinity of Sterol 14α-Demethylase (CYP51) Enzymes from Candida albicans and Homo sapiens
Authors: Warrilow Andrew G. , Parker Josie E. , Kelly Diane E. , Kelly Steven L. 
Published: December 2012

ABSTRACTCandida albicansCYP51 (CaCYP51) (Erg11), full-lengthHomo sapiensCYP51 (HsCYP51), and truncated Δ60HsCYP51 were expressed inEscherichia coliand purified to homogeneity. CaCYP51 and both HsCYP51 enzymes bound lanosterol (Ks, 14 to 18 μM) and catalyzed the 14α-demethylation of lanosterol usingHomo sapienscytochrome P450 reductase and NADPH as redox partners. Both HsCYP51 enzymes bound clotrimazole, itraconazole, and ketoconazole tightly (dissociation constants [Kds], 42 to 131 nM) but bound fluconazole (Kd, ∼30,500 nM) and voriconazole (Kd, ∼2,300 nM) weakly, whereas CaCYP51 bound all five medical azole drugs tightly (Kds, 10 to 56 nM). Selectivity for CaCYP51 over HsCYP51 ranged from 2-fold (clotrimazole) to 540-fold (fluconazole) among the medical azoles. In contrast, selectivity for CaCYP51 over Δ60HsCYP51 with agricultural azoles ranged from 3-fold (tebuconazole) to 9-fold (propiconazole). Prothioconazole bound extremely weakly to CaCYP51 and Δ60HsCYP51, producing atypical type I UV-visible difference spectra (Kds, 6,100 and 910 nM, respectively), indicating that binding was not accomplished through direct coordination with the heme ferric ion. Prothioconazole-desthio (the intracellular derivative of prothioconazole) bound tightly to both CaCYP51 and Δ60HsCYP51 (Kd, ∼40 nM). These differences in binding affinities were reflected in the observed 50% inhibitory concentration (IC50) values, which were 9- to 2,000-fold higher for Δ60HsCYP51 than for CaCYP51, with the exception of tebuconazole, which strongly inhibited both CYP51 enzymes. In contrast, prothioconazole weakly inhibited CaCYP51 (IC50, ∼150 μM) and did not significantly inhibit Δ60HsCYP51.
Function of Cytochrome P450 Enzymes RosC and RosD in the Biosynthesis of Rosamicin Macrolide Antibiotic Produced by Micromonospora rosaria
Authors: Iizaka Yohei , Higashi Noriko , Ishida Masanari , Oiwa Reina , Ichikawa Yumi , Takeda Moeka , Anzai Yojiro , Kato Fumio 
Published: December 2012

ABSTRACT

The cytochrome P450 enzyme-encoding genes
rosC
and
rosD
were cloned from the rosamicin biosynthetic gene cluster of
Micromonospora rosaria
IFO13697. The functions of RosC and RosD were demonstrated by gene disruption and complementation with
M. rosaria
and bioconversion of rosamicin biosynthetic intermediates with
Escherichia coli
expressing RosC and RosD. It is proposed that
M. rosaria
IFO13697 has two pathway branches that lead from the first desosaminyl rosamicin intermediate, 20-deoxo-20-dihydro-12,13-deepoxyrosamicin, to rosamicin.
Treatment with Telbivudine Positively Regulates Antiviral Immune Profiles in Chinese Patients with Chronic Hepatitis B
Authors: Ma Liang , Cai Yan-Jun , Yu Lei , Feng Jun-Yan , Wang Juan , Li Cong , Niu Jun-Qi , Jiang Yan-Fang 
Published: December 2012

ABSTRACTChronic infection with hepatitis B virus (HBV) is associated with impairment of T and NK cell immunity. This study was aimed at investigating the impact of treatment with telbivudine (LDT) on T and NK cell immunity in patients with chronic hepatitis B (CHB). A total of 54 CHB patients and 30 healthy controls (HC) were recruited. Individual patients were treated orally with 600 mg LDT daily for 13 months. The serum HBV DNA loads, the levels of the HBV-related biomarkers alanine aminotransferase (ALT) and aspartate transaminase (AST), and the numbers of different subsets of peripheral T and NK cells in subjects were measured before and longitudinally after LDT treatment. Following treatment with LDT, the serum HBV DNA loads and the percentages of HBsAg- or HBeAg-seropositive cases were gradually reduced, accompanied by decreased levels of serum ALT and AST. In comparison with the HC, fewer CD3−CD56+and CD244+NK cells and CD3+CD8+T cells, lower frequencies of cytokine+CD4+T cells, and more CD3+CD4+, CD4+CD25+Foxp3+, CD4+CD25+CD127low, and CD8+PD-1+T cells were detected in CHB patients. Treatment with LDT increased the numbers of NK and CD8+cells and the frequencies of cytokine+CD4+T cells but reduced the numbers of CD4+CD25+Foxp3+, CD4+CD25+CD127low, and CD8+PD-1+T cells in CHB patients. The frequencies of cytokine+CD4+T cells were negatively associated with the levels of serum HBV DNA, ALT, and AST. Thus, treatment with LDT inhibits HBV replication, modulates T and NK cell immunity, and improves liver function in Chinese patients with CHB.
Combinations of Lambda Interferon with Direct-Acting Antiviral Agents Are Highly Efficient in Suppressing Hepatitis C Virus Replication
Authors: Friborg Jacques , Levine Steven , Chen Chaoqun , Sheaffer Amy K. , Chaniewski Susan , Voss Stacey , Lemm Julie A. , McPhee Fiona 
Published: December 2012

ABSTRACT

The clinical efficacy of a pegylated form of human lambda 1 interferon (IFN-λ1; also referred to herein as lambda) has been demonstrated in patients chronically infected with hepatitis C virus (HCV) representing genotypes 1 through 4. In these proof-of-concept studies, lambda showed an improved safety profile compared to the pegylated form of alfa interferon (referred to herein as alfa). In the study described in this report, an assessment of the
in vitro
antiviral activity of type III IFNs toward different HCV replicons revealed that the unpegylated recombinant form of IFN-λ1 (rIFN-λ1) exerted the most robust effect, while rIFN-λ3 exhibited greater activity than rIFN-λ2. More importantly, cross-resistance to rIFN-λ1 was not observed in replicon cell lines known to have reduced susceptibility to investigational direct-acting antiviral (DAA) agents targeting the essential HCV nonstructural protein NS3, NS5A, or NS5B. When combined with either rIFN-α, the NS3 protease inhibitor (NS3 PI) asunaprevir (ASV), the NS5A replication complex inhibitor (NS5A RCI) daclatasvir (DCV), or the NS5B polymerase site I inhibitor (NS5B I) BMS-791325, rIFN-λ1 displayed a mixture of additive and synergistic effects. In three-drug combination studies, inclusion of lambda with ASV and DCV also yielded additive to synergistic effects. In line with these observations, it was demonstrated that a regimen that used a combination of rIFN-λ1 with one or two DAAs was superior to an IFN-free regimen in clearing HCV RNA in genotype 1a cell lines representing wild-type and NS3 protease inhibitor-resistant sequences. Overall, these data support further clinical development of lambda as part of alternative combination treatments with DAAs for patients chronically infected with HCV.
Azithromycin Kills Invasive Aggregatibacter actinomycetemcomitans in Gingival Epithelial Cells
Authors: Lai Pin-Chuang , Walters John D. 
Published: December 2012

ABSTRACT

Aggregatibacter actinomycetemcomitans
invades periodontal pocket epithelium and is therefore difficult to eliminate by periodontal scaling and root planing. It is susceptible to azithromycin, which is taken up by many types of mammalian cells. This led us to hypothesize that azithromycin accumulation by gingival epithelium could enhance the killing of intraepithelial
A. actinomycetemcomitans
. [
3
H]azithromycin transport by Smulow-Glickman gingival epithelial cells and SCC-25 oral epithelial cells was characterized. To test our hypothesis, we infected cultured Smulow-Glickman cell monolayers with
A. actinomycetemcomitans
(Y4 or SUNY 465 strain) for 2 h, treated them with gentamicin to eliminate extracellular bacteria, and then incubated them with azithromycin for 1 to 4 h. Viable intracellular bacteria were released, plated, and enumerated. Azithromycin transport by both cell lines exhibited Michaelis-Menten kinetics and was competitively inhibited by
l-
carnitine and several other organic cations. Cell incubation in medium containing 5 μg/ml azithromycin yielded steady-state intracellular concentrations of 144 μg/ml in SCC-25 cells and 118 μg/ml in Smulow-Glickman cells. Azithromycin induced dose- and time-dependent intraepithelial killing of both
A. actinomycetemcomitans
strains. Treatment of infected Smulow-Glickman cells with 0.125 μg/ml azithromycin killed approximately 29% of the intraepithelial CFU of both strains within 4 h, while treatment with 8 μg/ml azithromycin killed ≥82% of the CFU of both strains (
P
< 0.05). Addition of carnitine inhibited the killing of intracellular bacteria by azithromycin (
P
< 0.05). Thus, human gingival epithelial cells actively accumulate azithromycin through a transport system that facilitates the killing of intraepithelial
A. actinomycetemcomitans
and is shared with organic cations.
Continuous Cellulosic Bioethanol Fermentation by Cyclic Fed-Batch Cocultivation
Authors: Jiang He-Long , He Qiang , He Zhili , Hemme Christopher L. , Wu Liyou , Zhou Jizhong 
Published: December 2012

ABSTRACT

Cocultivation of cellulolytic and saccharolytic microbial populations is a promising strategy to improve bioethanol production from the fermentation of recalcitrant cellulosic materials. Earlier studies have demonstrated the effectiveness of cocultivation in enhancing ethanolic fermentation of cellulose in batch fermentation. To further enhance process efficiency, a semicontinuous cyclic fed-batch fermentor configuration was evaluated for its potential in enhancing the efficiency of cellulose fermentation using cocultivation. Cocultures of cellulolytic
Clostridium thermocellum
LQRI and saccharolytic
Thermoanaerobacter pseudethanolicus
strain X514 were tested in the semicontinuous fermentor as a model system. Initial cellulose concentration and pH were identified as the key process parameters controlling cellulose fermentation performance in the fixed-volume cyclic fed-batch coculture system. At an initial cellulose concentration of 40 g liter
−1
, the concentration of ethanol produced with pH control was 4.5-fold higher than that without pH control. It was also found that efficient cellulosic bioethanol production by cocultivation was sustained in the semicontinuous configuration, with bioethanol production reaching 474 mM in 96 h with an initial cellulose concentration of 80 g liter
−1
and pH controlled at 6.5 to 6.8. These results suggested the advantages of the cyclic fed-batch process for cellulosic bioethanol fermentation by the cocultures.
Rapid and Sensitive Method To Identify Mycobacterium avium subsp. paratuberculosis in Cow's Milk by DNA Methylase Genotyping
Authors: Mundo Silvia Leonor , Gilardoni Liliana Rosa , Hoffman Federico José , Lopez Osvaldo Jorge 
Published: December 2012

ABSTRACTParatuberculosis is an infectious, chronic, and incurable disease that affects ruminants, caused byMycobacterium aviumsubsp.paratuberculosis. This bacterium is shed primarily through feces of infected cows but can be also excreted in colostrum and milk and might survive pasteurization. Since an association of genomic sequences ofM. aviumsubsp.paratuberculosisin patients with Crohn's disease has been described; it is of interest to rapidly detectM. aviumsubsp.paratuberculosisin milk for human consumption. IS900insertion is used as a target for PCR amplification to identify the presence ofM. aviumsubsp.paratuberculosisin biological samples. Two target sequences were selected: IS1(155 bp) and IS2(94 bp). These fragments have a 100% identity among allM. aviumsubsp.paratuberculosisstrains sequenced.M. aviumsubsp.paratuberculosiswas specifically concentrated from milk samples by immunomagnetic separation prior to performing PCR. The amplicons were characterized using DNA methylase Genotyping, i.e., the amplicons were methylated with 6-methyl-adenine and digested with restriction enzymes to confirm their identity. The methylated amplicons from 100 CFU ofM. aviumsubsp.paratuberculosiscan be visualized in a Western blot format using an anti-6-methyl-adenine monoclonal antibody. The use of DNA methyltransferase genotyping coupled to a scintillation proximity assay allows for the detection of up to 10 CFU ofM. aviumsubsp.paratuberculosisper ml of milk. This test is rapid and sensitive and allows for automation and thus multiple samples can be tested at the same time.
Heterologous Overexpression and Characterization of a Flavoprotein-Cytochrome
c
Complex Fructose Dehydrogenase of Gluconobacter japonicus NBRC3260
Authors: Kawai Shota , Goda-Tsutsumi Maiko , Yakushi Toshiharu , Kano Kenji , Matsushita Kazunobu 
Published: December 2012

ABSTRACT

A heterotrimeric flavoprotein-cytochrome
c
complex fructose dehydrogenase (FDH) of
Gluconobacter japonicus
NBRC3260 catalyzes the oxidation of
d
-fructose to produce 5-keto-
d
-fructose and is used for diagnosis and basic research purposes as a direct electron transfer-type bioelectrocatalysis. The
fdhSCL
genes encoding the FDH complex of
G. japonicus
NBRC3260 were isolated by a PCR-based gene amplification method with degenerate primers designed from the amino-terminal amino acid sequence of the large subunit and sequenced. Three open reading frames for
fdhSCL
encoding the small, cytochrome
c
, and large subunits, respectively, were found and were presumably in a polycistronic transcriptional unit. Heterologous overexpression of
fdhSCL
was conducted using a broad-host-range plasmid vector, pBBR1MCS-4, carrying a DNA fragment containing the putative promoter region of the membrane-bound alcohol dehydrogenase gene of
Gluconobacter oxydans
and a
G. oxydans
strain as the expression host. We also constructed derivatives modified in the translational initiation codon to ATG from TTG, designated
TTG
FDH and
ATG
FDH. Membranes of the cells producing recombinant
TTG
FDH and
ATG
FDH showed approximately 20 times and 100 times higher specific activity than those of
G. japonicus
NBRC3260, respectively. The cells producing only FdhS and FdhL had no fructose-oxidizing activity, but showed significantly high
d
-fructose:ferricyanide oxidoreductase activity in the soluble fraction of cell extracts, whereas the cells producing the FDH complex showed activity in the membrane fraction. It is reasonable to conclude that the cytochrome
c
subunit is responsible not only for membrane anchoring but also for ubiquinone reduction.