bluuebunny/crossref_metadata_2025_split huggingface dataset:
Divalent Metal Cations Increase the Activity of the Antimicrobial Peptide Kappacin
Authors: Dashper Stuart G. , O'Brien-Simpson Neil M. , Cross Keith J. , Paolini Rita A. , Hoffmann Brigitte , Catmull Deanne V. , Malkoski Marina , Reynolds Eric C. 
Published: May 2005

ABSTRACT

Kappacin, nonglycosylated κ-casein(106-169), is a novel antimicrobial peptide produced from κ-casein found in bovine milk. There are two major genetic forms of kappacin, A and B, and using synthetic peptides corresponding to the active region, κ-casein(138-158), of these forms, we have shown that the Asp
148
to Ala
148
substitution is responsible for the lesser antibacterial activity of κ-casein-B(106-169). Kappacin was shown to have membranolytic action at concentrations above 30 μM at acidic pH when tested against artificial liposomes. There was little membranolytic activity at neutral pH, which is consistent with the lack of antibacterial activity of kappacin against
Streptococcus mutans
at this pH. Kappacin specifically bound two zinc or calcium ions per mol, and this binding enhanced antibacterial activity at neutral pH. Nuclear magnetic resonance analysis indicated that a κ-casein-A(138-158) synthetic peptide undergoes a conformational change in the presence of the membrane solvent trifluoroethanol and excess divalent metal ions. This change in conformation is presumably responsible for the increase in antibacterial activity of kappacin detected in the presence of excess zinc or calcium ions at neutral pH. When tested against the oral bacterial pathogen
S. mutans
cultured as a biofilm in a constant-depth film fermentor, a preparation of 10 g/liter kappacin and 20 mM ZnCl
2
reduced bacterial viability by 3 log
10
and suppressed recovery of viability. In contrast 20 mM ZnCl
2
alone reduced bacterial viability by ≈1 log
10
followed by rapid recovery. In conclusion, kappacin has a membranolytic, antibacterial effect that is enhanced by the presence of divalent cations.
Biological Cost of Single and Multiple Norfloxacin Resistance Mutations in
Escherichia coli
Implicated in Urinary Tract Infections
Authors: Lindgren Patricia Komp , Marcusson Linda L. , Sandvang Dorthe , Frimodt-Møller Niels , Hughes Diarmaid 
Published: May 2005

ABSTRACT

Resistance to fluoroquinolones in urinary tract infection (UTIs) caused by
Escherichia coli
is associated with multiple mutations, typically those that alter DNA gyrase and DNA topoisomerase IV and those that regulate AcrAB-TolC-mediated efflux. We asked whether a fitness cost is associated with the accumulation of these multiple mutations. Mutants of the susceptible
E. coli
UTI isolate Nu14 were selected through three to five successive steps with norfloxacin. Each selection was performed with the MIC of the selected strain. After each selection the MIC was measured; and the regions of
gyrA
,
gyrB
,
parC
, and
parE
, previously associated with resistance mutations, and all of
marOR
and
acrR
were sequenced. The first selection step yielded mutations in
gyrA
,
gyrB
, and
marOR
. Subsequent selection steps yielded mutations in
gyrA
,
parE
, and
marOR
but not in
gyrB
,
parC
, or
acrR
. Resistance-associated mutations were identified in almost all isolates after selection steps 1 and 2 but in less than 50% of isolates after subsequent selection steps. Selected strains were competed in vitro, in urine, and in a mouse UTI infection model against the starting strain, Nu14. First-step mutations were not associated with significant fitness costs. However, the accumulation of three or more resistance-associated mutations was usually associated with a large reduction in biological fitness, both in vitro and in vivo. Interestingly, in some lineages a partial restoration of fitness was associated with the accumulation of additional mutations in late selection steps. We suggest that the relative biological costs of multiple mutations may influence the evolution of
E. coli
strains that develop resistance to fluoroquinolones.
Intravesical Nitric Oxide Delivery for Prevention of Catheter-Associated Urinary Tract Infections
Authors: Carlsson Stefan , Weitzberg Eddie , Wiklund Peter , Lundberg Jon O. 
Published: May 2005

ABSTRACT

The use of indwelling urinary catheters is a major risk factor for urinary tract infection; and despite the availability of numerous preventive regimens, this condition is still extremely common. In earlier studies we have demonstrated the inhibitory effects of nitrite and ascorbic acid on bacterial growth in urine. When combined, these compounds generate antibacterial reactive nitrogen species, including the gas nitric oxide. We have now tested in a laboratory model of the urinary bladder whether filling of the catheter retention balloon with nitrite and ascorbic acid would generate measurable amounts of NO outside the membrane and whether this would affect bacterial growth in the surrounding urine. Two strains of
Escherichia coli
, one strain isolated from a patient (U1106024) and one reference strain (ATCC 25922), were tested. Nitric oxide gas was generated in the silicone balloon and readily diffused into the urine. When control catheters with ascorbic acid but without nitrite were used, bacterial counts increased from 9.0 × 10
5
to 2.0 ×10
8
CFU/ml (strain U1106024) and from 2.5 × 10
6
to 2.7 × 10
8
CFU/ml (strain ATCC 25922) after 24 h. In contrast, in test catheters with ascorbic acid and nitrite, both strains tested were effectively killed. The NO donor {DETA NONOate, (
Z
)-1-[
N
-(2-aminoethyl)-
N
-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate} also showed antibacterial activity in the same model, thereby supporting a central role of NO in achieving the observed effects. Future clinical trials will reveal whether this novel approach for the intravesical delivery of an antibacterial gas could be used to prevent catheter-associated infections.
Inhibitory Activity of Human Immunodeficiency Virus Aspartyl Protease Inhibitors against
Encephalitozoon intestinalis
Evaluated by Cell Culture-Quantitative PCR Assay
Authors: Menotti Jean , Santillana-Hayat Maud , Cassinat Bruno , Sarfati Claudine , Derouin Francis , Molina Jean-Michel 
Published: May 2005

ABSTRACT

Immune reconstitution might not be the only factor contributing to the low prevalence of microsporidiosis in human immunodeficiency virus (HIV)-infected patients treated with protease inhibitors, as these drugs may exert a direct inhibitory effect against fungi and protozoa. In this study, we developed a cell culture-quantitative PCR assay to quantify
Encephalitozoon intestinalis
growth in U-373-MG human glioblastoma cells and used this assay to evaluate the activities of six HIV aspartyl protease inhibitors against
E. intestinalis
. A real-time quantitative PCR assay targeted the
E. intestinalis
small-subunit rRNA gene. HIV aspartyl protease inhibitors were tested over serial concentrations ranging from 0.2 to 10 mg/liter, with albendazole used as a control. Ritonavir, lopinavir, and saquinavir were able to inhibit
E. intestinalis
growth, with 50% inhibitory concentrations of 1.5, 2.2, and 4.6 mg/liter, respectively, whereas amprenavir, indinavir, and nelfinavir had no inhibitory effect. Pepstatin A, a reference aspartyl protease inhibitor, could also inhibit
E. intestinalis
growth, suggesting that HIV protease inhibitors may act through the inhibition of an
E. intestinalis
-encoded aspartyl protease. These results showed that some HIV protease inhibitors can inhibit
E. intestinalis
growth at concentrations that are achievable in vivo and that the real-time quantitative PCR assay that we used is a valuable tool for the in vitro assessment of the activities of drugs against
E. intestinalis
.
Interferon Alfacon-1 Protects Hamsters from Lethal Pichinde Virus Infection
Authors: Gowen Brian B. , Barnard Dale L. , Smee Donald F. , Wong Min-Hui , Pace Anne M. , Jung Kie-Hoon , Winslow Scott G. , Bailey Kevin W. , Blatt Lawrence M. , Sidwell Robert W. 
Published: May 2005

ABSTRACT

Hemorrhagic fever of arenaviral origin is a frequently fatal infectious disease of considerable priority to the biodefense mission. Historically, the treatment of arenaviral infections with alpha interferons has not yielded favorable results. Here we present evidence that interferon alfacon-1, a nonnaturally occurring bioengineered alpha interferon approved for the treatment of chronic hepatitis C, is active against Pichinde and Tacaribe arenaviruses in cell culture. In the hamster model of Pichinde virus (PCV) infection, interferon alfacon-1 treatment significantly protected animals from death, prolonged the survival of those that eventually died, reduced virus titers, and limited liver damage characteristic of PCV-induced disease. Moreover, interferon alfacon-1 also demonstrated therapeutic activity, to a lesser degree, when the initiation of treatment was delayed up to 2 days post-virus challenge. Despite the observed advantages of interferon alfacon-1 therapy, efforts to stimulate the immune system with the known interferon inducer poly(I:C
12
U) (Ampligen) offered only limited protection against lethal PCV challenge. Taken together, these data suggest that the increased potency of the bio-optimized interferon alfacon-1 molecule may be critical to the observed antiviral effects. These data are the first report demonstrating efficacious treatment of acute arenaviral disease with alpha interferon therapy, and further study is warranted.
Mosaic Structure of a Multiple-Drug-Resistant, Conjugative Plasmid from
Campylobacter jejuni
Authors: Nirdnoy Warawadee , Mason Carl J. , Guerry Patricia 
Published: May 2005

ABSTRACT

Partial sequence analysis of a
tet
(O) plasmid from a multiple-drug-resistant clinical isolate of
Campylobacter jejuni
revealed 10 genes or pseudogenes encoding different aminoglycoside inactivating enzymes, transposase-like genes, and multiple unknown genes from a variety of pathogenic and commensal bacteria. The plasmid could be mobilized by a P incompatibility group plasmid into
Escherichia coli
, where it apparently integrated into the chromosome and expressed high-level resistance to multiple aminoglycoside antibiotics. This work provides new information about both the nature of drug resistance in
C. jejuni
and the ability of
C. jejuni
to exchange genes with other bacterial species.
Fluoroquinolone-Resistant
Streptococcus agalactiae
: Epidemiology and Mechanism of Resistance
Authors: Wehbeh Wehbeh , Rojas-Diaz Roberto , Li Xinying , Mariano Noriel , Grenner Louise , Segal-Maurer Sorana , Tommasulo Barbara , Drlica Karl , Urban Carl , Rahal James J. 
Published: May 2005

ABSTRACT

Quinolone-resistant
Streptococcus agalactiae
bacteria were recovered from single-patient isolates and found to contain mutations in the gyrase and topoisomerase IV genes. Pulsed-field gel electrophoresis demonstrated that four isolates from the same long-term care facility were closely related; in seven cases, quinolone-resistant
Haemophilus influenzae
and
S. agalactiae
bacteria were isolated from the same patient.
In Vitro Activity and Killing Effect of Citropin 1.1 against Gram-Positive Pathogens Causing Skin and Soft Tissue Infections
Authors: Giacometti Andrea , Cirioni Oscar , Kamysz Wojciech , Silvestri Carmela , Del Prete Maria Simona , Licci Alberto , D'Amato Giuseppina , Łukasiak Jerzy , Scalise Giorgio 
Published: May 2005

ABSTRACTThe in vitro activity of citropin 1.1 against gram-positive cocci was measured by MIC, minimal bactericidal concentration, time-kill studies, and a checkerboard titration method. Streptococci and staphylococci were inhibited at concentrations between 1 and 16 mg/liter, respectively. Enterococci showed less susceptibility. Synergy was demonstrated when citropin 1.1 was combined with clarithromycin and doxycycline.
In Vitro Activity of Doripenem (S-4661) against Multidrug-Resistant Gram-Negative Bacilli Isolated from Patients with Cystic Fibrosis
Authors: Chen Yunhua , Garber Elizabeth , Zhao Qiuqu , Ge Yigong , Wikler Matthew A. , Kaniga Koné , Saiman Lisa 
Published: May 2005

ABSTRACT

Doripenem 50% inhibitory concentrations (MIC
50
) and 90% inhibitory concentrations (MIC
90
) for multidrug-resistant strains of mucoid
Pseudomonas aeruginosa
(
n
= 200 strains), nonmucoid
P. aeruginosa
(
n
= 200), and
Burkholderia cepacia
complex (
n
= 200) isolated from patients with cystic fibrosis were 8 and 32, 8 and 64, and 8 and 32 μg/ml, respectively. Doripenem had somewhat better activity than established antimicrobial agents.
Class I Integron with a Group II Intron Detected in an
Escherichia coli
Strain from a Free-Range Reindeer
Authors: Sunde Marianne 
Published: May 2005

ABSTRACT

An
Escherichia coli
strain, isolated from wild reindeer in a remote mountain area, contained a class 1 integron with two unusual features: a group II intron and a cassette with homology to a superintegron cassette. Alignments indicate that
attC
sites of gene cassettes may be insertion sites for introns.
Isolation and Expression of a Novel Molecular Class D β-Lactamase, OXA-61, from
Campylobacter jejuni
Authors: Alfredson David A. , Korolik Victoria 
Published: May 2005

ABSTRACT

A novel β-lactamase gene,
bla
OXA-61
, from
Campylobacter jejuni
GC015 was cloned and its nucleotide sequence determined.
bla
OXA-61
encodes a protein of 257 amino acids in which the active-site STFK tetrad and conserved class D β-lactamase motifs YGN and KTG were identified. A conserved sequence upstream of
bla
OXA-61
is required for expression in
Campylobacter
.
Multicenter Study of the Mechanisms of Resistance and Clonal Relationships of
Streptococcus agalactiae
Isolates Resistant to Macrolides, Lincosamides, and Ketolides in Spain
Authors: Gonzalez J. J. , Andreu A. 
Published: May 2005

ABSTRACT

Macrolide, lincosamide, and ketolide mechanisms of resistance and clonal relationships were characterized in a collection of 79 resistant group B streptococcus isolates obtained from neonates or pregnant women. The
erm
(B),
erm
(TR), and
mef
(A) genes were present in 62%, 30.4%, and 3.8% of the isolates, respectively. There was considerable clonal diversity among them.
Selection of Cross-Resistance following Exposure of
Pseudomonas aeruginosa
Clinical Isolates to Ciprofloxacin or Cefepime
Authors: Alyaseen Samer A. , Piper Kerryl E. , Rouse Mark S. , Steckelberg James M. , Patel Robin 
Published: May 2005

ABSTRACT

Exposure of ciprofloxacin- and cefepime-susceptible
Pseudomonas aeruginosa
isolates to increasing concentrations of ciprofloxacin selected for ciprofloxacin resistance in 26/27 and cefepime nonsusceptibility in 7/27 isolates. Exposure of the isolates to increasing concentrations of cefepime selected for cefepime nonsusceptibility in 20/27 isolates but not for ciprofloxacin resistance.
ErmB Determinants and Tn
916
-Like Elements in Clinical Isolates of
Clostridium difficile
Authors: Spigaglia Patrizia , Carucci Valentina , Barbanti Fabrizio , Mastrantonio Paola 
Published: May 2005

ABSTRACT

Erythromycin and tetracycline resistance was analyzed in 37
Clostridium difficile
clinical isolates. Strains of different clonal origins showed different erythromycin and tetracycline resistance determinants and different genetic arrangements of the elements. In strains of recent isolation, the presence of Tn
916
-like elements, never found before in
C. difficile
clinical isolates, has been demonstrated.
Decreasing Prevalence of β-Lactamase Production among Respiratory Tract Isolates of
Haemophilus influenzae
in the United States
Authors: Heilmann Kris P. , Rice Cassie L. , Miller Ashley L. , Miller Norma J. , Beekmann Susan E. , Pfaller Michael A. , Richter Sandra S. , Doern Gary V. 
Published: May 2005

ABSTRACT

A total of 986 isolates of
Haemophilus influenzae
from patients with respiratory tract infections in 45 United States medical centers were characterized during the winter of 2002-2003. β-Lactamase production was noted with 26.2% of isolates; 14.6% were resistant to trimethoprim-sulfamethoxazole. Resistance to other relevant antimicrobial agents was extremely uncommon. In comparison to the results of four previous national surveys conducted since 1994, the prevalence of β-lactamase production with this pathogen appears to be decreasing.
Posttreatment Changes in
Escherichia coli
Antimicrobial Susceptibility Rates among Diarrheic Patients Treated with Ciprofloxacin
Authors: Putnam Shannon D. , Sanders John W. , Tribble David R. , Rockabrand David R. , Riddle Mark S. , Rozmajzl Patrick J. , Frenck Robert W. 
Published: May 2005

ABSTRACT

Changes in antimicrobial resistance of
Escherichia coli
among deployed U.S. military personnel being treated for diarrhea were evaluated. Stool samples were collected pretreatment and on days 7, 14, and 28 posttreatment. Resistance to ciprofloxacin was noted in 13.3% of baseline specimens, and rates of resistance against multiple antibiotics increased dramatically from baseline to day 7 and then tapered off to return to pretreatment levels by day 28, except for ciprofloxacin, suggesting that population accumulative usage of fluoroquinolones may result in an incremental increase in resistance rates.
Influence of cytokine and ICAM-1 gene polymorphisms on susceptibility to chronic pancreatitis
Authors: Howell W M , Pead P J , Shek F W , Rose-Zerilli M J , Armstrong T , Johnson C D , Fine D R , Iredale J P , Bateman A C 
Published: May 2005

Aims:To test the hypothesis that single nucleotide polymorphisms (SNPs) within genes (or their promoter regions) encoding cytokines, growth factors, and intercellular adhesion molecules modulate the risk of development of chronic pancreatitis (CP).Methods:DNA was extracted from peripheral blood leucocytes or formalin fixed, paraffin wax embedded tissue from 53 patients with CP and 266 healthy controls. SNPs within the interleukin 1β (IL-1β), IL-6, IL-8, tumour necrosis factor α (TNFα) and vascular endothelial growth factor (VEGF) gene promoter regions and the transforming growth factor β1 (TGFβ1) and intercellular cell adhesion molecule 1 (ICAM-1) genes were genotyped by the amplification refractory mutation system polymerase chain reaction or 5′ nuclease (Taqman®) techniques. Patient–control comparisons were made using 2 × 2 contingency tables and χ2analyses.Results:A non-significant decrease in the frequency of the IL-8 −251 AA genotype and a non-significant increase in the frequency of the ICAM-1 +469 GA genotype was seen in patients compared with controls. No associations were identified between SNPs in the promoter regions of the IL-1β, IL-6, or TNFα proinflammatory cytokines genes or the TGFβ1 and VEGF genes and susceptibility to CP.Conclusions:This preliminary study suggests that genetic polymorphism within several cytokine genes is unlikely to influence susceptibility to CP, but the possible role of IL-8 and ICAM-1 polymorphisms in the development of this disease requires further investigation.
Lymphoma associated chromosomal abnormalities can easily be detected by FISH on tissue imprints. An underused diagnostic alternative
Authors: Buño I , Nava P , Álvarez-Doval A , Álvarez-Rodríguez F , Díez-Martín J L , Menárguez J 
Published: May 2005

Background:Fluorescence in situ hybridisation (FISH) is useful for detecting specific chromosomal abnormalities in various tumours. In lymphomas, diagnosis is frequently made using paraffin wax embedded tissue. However, FISH performed under these conditions presents potential technical problems and difficulties in interpretation.Aims:To show that FISH using tissue imprints and cytopreps or alternatively, bone marrow (BM) smears, constitutes an easy and rapid strategy to overcome these constraints.Methods:The study comprised 46 patients with lymphoma. Sixty nine tissue imprints, cytopreps, or BM smears were analysed by FISH. Dual colour, dual fusion FISH probes were used to detect the t(8;14), t(11;14), and t(14;18) translocations, whereas a dual colour breakapart FISH probe was used to detect chromosomal translocations involving the BCL6 gene.Results:Tissue imprints and cytopreps were successfully hybridised in all 52 cases, whereas hybridisation was successful in 16 of 17 archival BM smears. All patients could be analysed to identify either the presence or absence of chromosomal translocations.Conclusions:The use of tissue imprints, cytopreps, or BM smears to identify chromosomal abnormalities by FISH is a rapid and useful ancillary approach for diagnostic purposes. Therefore, it could be used on a routine basis whenever fresh samples are available.
Differential expression of the eukaryotic release factor 3 (eRF3/GSPT1) according to gastric cancer histological types
Authors: Malta-Vacas J , Aires C , Costa P , Conde A R , Ramos S , Martins A P , Monteiro C , Brito M 
Published: May 2005

Background:There are now several lines of evidence to suggest that protein synthesis and translation factors are involved in the regulation of cell proliferation and cancer development.Aims:To investigate gene expression patterns of eukaryotic releasing factor 3 (eRF3) in gastric cancer.Methods:RNA was prepared from 25 gastric tumour biopsies and adjacent non-neoplastic mucosa. Real time TaqMan reverse transcription polymerase chain reaction (RT-PCR) was performed to measure the relative gene expression levels. DNA was isolated from tumour and normal tissues and gene dosage was determined by a quantitative real time PCR using SYBR Green dye.Results:Different histological types of gastric tumours were analysed and nine of the 25 tumours revealed eRF3/GSPT1 overexpression; moreover, eight of the 12 intestinal type carcinomas analysed overexpressed the gene, whereas eRF3/GSPT1 was overexpressed in only one of the 10 diffuse type carcinomas (Kruskal-Wallis Test; p < 0.05). No correlation was found between ploidy and transcript expression levels of eRF3/GSPT1. Overexpression of eRF3/GSPT1 was not associated with increased translation rates because the upregulation of eRF3/GSPT1 did not correlate with increased eRF1 levels.Conclusions:Overexpression of eRF3/GSPT1 in intestinal type gastric tumours may lead to an increase in the translation efficiency of specific oncogenic transcripts. Alternatively, eRF3/GSPT1 may be involved in tumorigenesis as a result of its non-translational roles, namely (dis)regulating the cell cycle, apoptosis, or transcription.
BRAF and NRAS mutations are uncommon in melanomas arising in diverse internal organs
Authors: Wong C W , Fan Y S , Chan T L , Chan A S W , Ho L C , Ma T K F , Yuen S T , Leung S Y 
Published: May 2005

Background:Malignant melanoma arising from different body compartments may be associated with differing aetiological factors and clinical behaviour, and may manifest diverse molecular genetic profiles. Although many studies have focused on cutaneous melanoma, little is known of mucosal and other types of melanoma. In particular, malignant melanoma of soft parts is different from other melanomas in many respects, yet manifests a common melanocytic differentiation. Mutation of BRAF is now known to be common in cutaneous melanomas, and raises possible new therapeutic options of anti-RAF treatment for these patients. Few data are available for non-cutaneous melanomas.Aims:To study the incidence of BRAF and NRAS mutations in melanomas arising in diverse internal organs.Methods:Fifty one melanomas from various internal organs were investigated for BRAF and NRAS mutation by direct DNA sequencing.Results:BRAF and NRAS mutations were found in two and five mucosal melanomas arising from the aerodigestive and female genital tracts (n = 36). Their occurrence is mutually exclusive, giving a combined mutation incidence rate of 19.4% in mucosal melanomas. Both BRAF and NRAS mutations were absent in malignant melanoma of soft parts (n = 7). BRAF mutation was also absent in uveal melanoma (n = 6), but was seen in two of five cutaneous melanomas. The incidence of BRAF or combined BRAF/NRAS mutations in all non-cutaneous groups was significantly lower than published rates for cutaneous melanomas.Conclusion:Each melanoma subtype may have a unique oncogenetic pathway of tumour development, and only a small fraction of non-cutaneous melanomas may benefit from anti-RAF treatment.