bluuebunny/crossref_metadata_2025_split huggingface dataset:
Melatonin treatments reduce the pathogenicity and inhibit the growth of Xanthomonas oryzae pv. oryzicola
Authors: Chen X. , Sun C. , Laborda P. , He Y. , Zhao Y. , Li C. , Liu F. 
Published: October 2018

Rice bacterial leaf streak (BLS), caused by Xanthomonas oryzae pv. oryzicola (Xoc), is a prevalent disease worldwide. Melatonin, an indoleamine with the chemical name N‐acetyl‐5‐methoxytryptamine, is known to inhibit the growth of human pathogenic bacteria. However, the impact of melatonin on agricultural pathogenic bacteria remains poorly understood. In this study, the effect of melatonin on Xoc was investigated. Exogenous melatonin (200 μg mL−1) significantly inhibited the growth of Xoc and reduced the mRNA expression level of seven cell division‐related genes. Melatonin reduced the pathogenicity of Xoc towards the susceptible rice IR24. The lesion length in IR24 infected by Xoc pretreated with melatonin (200 μg mL−1) was more than 23% smaller than the lesion length of the control group. Similarly, infection of IR24 leaves by Xoc pretreated with melatonin (200 μg mL−1) reduced the bacterial population by 45%. The biofilm formation, swimming motility and extracellular protease activities of Xoc also decreased under melatonin treatment. Melatonin only slightly changed the morphology of Xoc but significantly reduced the mRNA expression of toxin genes. Furthermore, treating leaves with exogenous melatonin reduced the incidence of BLS by 17%. It is reported for the first time that melatonin reduces pathogenicity and may serve as a bactericide for controlling BLS disease.
Suicide Risk and Emotional Responses to Thoughts of Death: The Response to Morbid Ideations Questionnaire
Authors: Yaseen Zimri S. , Molina Nicolette , Hawes Mariah , Barzilay Shira , Galynker Igor 
Published: October 2018

BackgroundThere is need for deeper understanding of the processes by which suicidal thoughts lead to action. Examination of morbid ideation and the emotional sequelae of such ideation that may feed suicide ideation (SI) and attempts (SA) have been limited.MethodAdult psychiatric outpatients (N = 385) were administered the Response to Morbid Ideation Questionnaire (RMI‐Q) and measures of SI, suicidal thoughts and behaviors (STB), and other psychiatric symptom severity. We examined (1) incidence and prevalence in mentation of morbid ideations and emotional responses to these ideations, (2) differences in emotional responses between individuals of varying levels of suicide history, and (3) the relationships of different types of morbid ideations and emotional responses with concurrent SI and symptom severity.ResultsMorbid ideation was reported by 87.5% of participants and associated with lifetime and concurrent levels of SI/STB. Calm/relieved emotional responses were associated with lifetime and concurrent levels of SI/STB, while negative‐valence responses to morbid ideations were associated with concurrent severity of psychopathology.ConclusionsOur results suggest that the role of morbid ideation and its emotional sequelae in the development of suicidal motivation and action deserves further attention and may be a treatment target for suicide risk reduction.
Species delimitation in Neotropical fishes of the genus Characidium (Teleostei, Characiformes)
Authors: Serrano Érica A. , Melo Bruno F. , Freitas‐Souza Diogo , Oliveira Maria L. M. , Utsunomia Ricardo , Oliveira Claudio , Foresti Fausto 
Published: October 2018

AbstractNeotropical darters of the genus Characidium have a complex systematic history with several examples of sympatry throughout their distribution range in Neotropical freshwaters. Although various species within the genus have been used as models to investigate chromosomal evolution and biogeography, species boundaries and relationships still remain uncertain. Here, we use mitochondrial DNA sequences to perform species delimitation analyses within Characidium and test previous hypotheses of species richness within the Characidium zebra complex and among sympatric morphotypes of C. alipioi. Results indicate high genetic distances within tested species complexes and revealed the presence of strongly supported lineages such as the large C. lauroi group from southeastern Brazil. This suggests that the evolutionary history of these groups may be correlated with biogeographic history. Analyses also reveal that three geographically isolated populations of C. zebra represent a single species, leading us to reject prior hypothesis of multiple species. Species delimitation using mitochondrial data strongly supports the presence of two sympatric species within C. alipioi in southeastern Brazil despite limited morphological variation and conserved chromosomal patterns. These results provide a framework to further the study of systematics and evolution within Characidium.
Contemporary Nutrition Interventions to Optimize Performance in Middle-Distance Runners
Authors: Stellingwerff Trent , Bovim Ingvill Måkestad , Whitfield Jamie 
Published: October 2018

Middle-distance runners utilize the full continuum of energy systems throughout training, and given the infinite competition tactical scenarios, this event group is highly complex from a performance intervention point of view. However, this complexity results in numerous potential periodized nutrition interventions to optimize middle-distance training adaptation and competition performance. Middle-distance race intensity is extreme, with 800- to 5,000-m races being at ∼95% to 130% of VO2max. Accordingly, elite middle-distance runners have primarily Type IIa/IIx fiber morphology and rely almost exclusively on carbohydrate (primarily muscle glycogen) metabolic pathways for producing adenosine triphosphate. Consequently, the principle nutritional interventions that should be emphasized are those that optimize muscle glycogen contents to support high glycolytic flux (resulting in very high lactate values, of >20 mmol/L in some athletes) with appropriate buffering capabilities, while optimizing power to weight ratios, all in a macro- and microperiodized manner. From youth to elite level, middle-distance athletes have arduous racing schedules (10–25 races/year), coupled with excessive global travel, which can take a physical and emotional toll. Accordingly, proactive and integrated nutrition planning can have a profound recovery effect over a long race season, as well as optimizing recovery during rounds of championship racing. Finally, with evidence-based implementation and an appropriate risk/reward assessment, several ergogenic aids may have an adaptive and/or performance-enhancing effect in the middle-distance athlete. Given that elite middle-distance athletes undertake ∼400 to 800 training sessions with 10–25 races/year, there are countless opportunities to implement various periodized acute and chronic nutrition-based interventions to optimize performance.
Functional Hip Characteristics and Their Relationship With Ball Velocity in College Baseball Pitchers
Authors: Yanagisawa Osamu , Wakamatsu Kenta , Taniguchi Hidenori 
Published: October 2018

Context: Compared to shoulder and elbow functions, the hip functional characteristics of baseball pitchers have not been fully investigated. Therefore, little is known about the relationship between hip function and pitching performance. Objective: The purpose of this study was to evaluate the characteristics of hip flexibility and strength, focusing on their influences on the ball velocity in baseball pitchers. Design: Descriptive laboratory study. Setting: Laboratory and university baseball facility. Participants: Twenty-three college baseball pitchers. Interventions: Passive hip range of motion (ROM) and isometric hip muscle strength were bilaterally measured. The pitchers threw 20 fastballs at an official pitching distance. Main Outcome Measures: Bilateral hip ROM and strength in flexion, extension, abduction, adduction, and external and internal rotation; the maximal ball velocity. Results: The pivot side showed smaller hip external rotation ROM (P < .01), larger hip internal rotation ROM (P = .03), and greater hip adduction strength (P = .03) than the stride side. The hip extension ROM on the stride side had a negative correlation with the maximal ball velocity (r = −.58, P < .01). The maximal ball velocity (135.3 [4.1] km/h) positively correlated with the hip extension (r = .59, P < .01), flexion (r = .57, P < .01), abduction (r = .55, P < .01), and adduction (r = .55, P < .01) strength on the pivot leg, and the hip flexion (r = .53, P = .01), abduction (r = .67, P < .01), and adduction (r = .46, P = .03) strength on the stride leg. Conclusions: These findings suggest that baseball pitchers do not have marked side-to-side differences in hip flexibility and strength, and that an important fitness factor for increasing ball velocity is not the hip flexibility but the hip muscle strength of both legs.
Randomized Comparison of Artemether-Benflumetol and Artesunate-Mefloquine in Treatment of MultidrugResistant Falciparum Malaria
Authors: van Vugt M. , Brockman A. , Gemperli B. , Luxemburger C. , Gathmann I. , Royce C. , Slight Thra , Looareesuwan S. , White N. J. , Nosten F. 
Published: October 2018

ABSTRACT

An open, randomized comparison of artemether-benflumetol (CGP 56 697; Novartis) with artesunate-mefloquine was conducted in 617 patients with acute uncomplicated multidrug-resistant falciparum malaria on the western border of Thailand. Both treatments rapidly and reliably cleared fever and parasitemia, and there was no significant difference in the initial therapeutic response parameters. Parasite genotyping was used to distinguish recrudescences from new infections. The 63-day cure rate for artesunate-mefloquine (94%) was significantly higher than the cure rate for artemether-benflumetol (81%) (
P
< 0.001). Both regimens were well tolerated. Nausea, vomiting, dizziness, sleep disorders, and other neurological side effects were between two and four times more common in the artesunate-mefloquine group than in the artemether-benflumetol group (
P
< 0.001). Artemether-benflumetol is effective and very well tolerated in the treatment of multidrug-resistant falciparum malaria. A higher dose than that used in the present study may improve efficacy.
Topoisomerase Mutations in Fluoroquinolone-Resistant and Methicillin-Susceptible and -Resistant Clinical Isolates of
Staphylococcus aureus
Authors: Kaatz Glenn W. , Seo Susan M. 
Published: October 2018

ABSTRACT

The incidence of the various mutations in the genes encoding topoisomerase IV and DNA gyrase in fluoroquinolone-resistant clinical isolates of
Staphylococcus aureus
is not known. Using restriction fragment length polymorphism analysis and DNA sequencing, we found that in fluoroquinolone- and methicillin-resistant strains, mutations in
grlA
and
gyrA
are quite likely to be present together. For fluoroquinolone-resistant but methicillin-susceptible strains, mutations in
grlA
alone are more common.
Efficacy of CS-834 against Experimental Pneumonia Caused by Penicillin-Susceptible and -Resistant
Streptococcus pneumoniae
in Mice
Authors: Fukuoka Takashi , Kawada Harumi , Kitayama Akiko , Koga Tetsufumi , Kubota Mikie , Harasaki Tamako , Kamai Yasuki , Ohya Satoshi , Yasuda Hiroshi , Iwata Masayuki , Kuwahara Shogo 
Published: October 2018

ABSTRACT

The efficacy of CS-834, a novel oral carbapenem, was assessed by using a murine model of pneumonia caused by penicillin-susceptible and penicillin-resistant
Streptococcus pneumoniae
and was compared with those of oral cephems, i.e., cefteram pivoxil, cefpodoxime proxetil, cefdinir, and cefditoren pivoxil. Intranasal inoculation of 10
6
CFU of penicillin-susceptible or penicillin-resistant
S. pneumoniae
in the exponential growth phase induced pneumonia and bacteremia in ddY mice within 48 h. For the treatment of infections caused by the penicillin-susceptible strain the antibiotics were administered orally at 0.4, 2, and 10 mg/kg of body weight twice daily for 2 days beginning at 24 h after bacterial inoculation, and for the treatment of infections caused by a penicillin-resistant strain the antibiotics were administered at 2, 10, and 50 mg/kg twice daily for 2 days beginning at 24 h after bacterial inoculation. Among the antibiotics tested, CS-834 exhibited the most potent efficacy against both types of strains. Against infections caused by penicillin-susceptible
S. pneumoniae
, CS-834 at all doses significantly reduced the numbers of viable cells in both the lungs and blood. Cefpodoxime proxetil at all doses and cefteram pivoxil and cefditoren pivoxil at doses of 2 and 10 mg/kg showed comparable efficacies. Against infections caused by penicillin-resistant
S. pneumoniae
, CS-834 at doses of 10 and 50 mg/kg showed the most potent efficacy among the antibiotics tested, resulting in the maximum decrease in the numbers of viable cells in the lungs. Comparable efficacies were observed with cefteram pivoxil and cefpodoxime proxetil at doses of 50 mg/kg each. The concentration of CS-834 in the lungs and blood was higher than that of cefdinir and was lower than those of the other antibiotics tested, suggesting that the potent therapeutic efficacy of CS-834 reflects its strong activity against
S. pneumoniae.
Host Mutations (
miaA
and
rpsL
) Reduce Tetracycline Resistance Mediated by Tet(O) and Tet(M)
Authors: Taylor Diane E. , Trieber Catharine A. , Trescher Gudrun , Bekkering Michelle 
Published: October 2018

ABSTRACT

The effects of mutations in host genes on tetracycline resistance mediated by the Tet(O) and Tet(M) ribosomal protection proteins, which originated in
Campylobacter
spp. and
Streptococcus
spp., respectively, were investigated by using mutants of
Salmonella typhimurium
and
Escherichia coli
. The
miaA
,
miaB
, and
miaAB
double mutants of
S. typhimurium
specify enzymes for tRNA modification at the adenosine at position 37, adjacent to the anticodon in tRNA. In
S. typhimurium
, this involves biosynthesis of
N
6
-(4-hydroxyisopentenyl)-2-methylthioadenosine (ms
2
io
6
A). The
miaA
mutation reduced the level of tetracycline resistance mediated by both Tet(O) and Tet(M), but the latter showed a greater effect, which was ascribed to the isopentenyl (i
6
) group or to a combination of the methylthioadenosine (ms
2
) and i
6
groups but not to the ms
2
group alone (specified by
miaB
). In addition, mutations in
E. coli rpsL
genes, generating both streptomycin-resistant and streptomycin-dependent strains, were also shown to reduce the level of tetracycline resistance mediated by Tet(O) and Tet(M). The single-site amino acid substitutions present in the
rpsL
mutations were pleiotropic in their effects on tetracycline MICs. These mutants affect translational accuracy and kinetics and suggest that Tet(O) and Tet(M) binding to the ribosome may be reduced or slowed in the
E. coli rpsL
mutants in which the S12 protein is altered. Data from both the
miaA
and
rpsL
mutant studies indicate a possible link between stability of the aminoacyl-tRNA in the ribosomal acceptor site and tetracycline resistance mediated by the ribosomal protection proteins.
Expression of
Pseudomonas aeruginosa
Multidrug Efflux Pumps MexA-MexB-OprM and MexC-MexD-OprJ in a Multidrug-Sensitive
Escherichia coli
Strain
Authors: Srikumar Ramakrishnan , Kon Tatiana , Gotoh Naomasa , Poole Keith 
Published: October 2018

ABSTRACT

The
mexCD-oprJ
and
mexAB-oprM
operons encode components of two distinct multidrug efflux pumps in
Pseudomonas aeruginosa
. To assess the contribution of individual components to antibiotic resistance and substrate specificity, these operons and their component genes were cloned and expressed in
Escherichia coli
. Western immunoblotting confirmed expression of the
P. aeruginosa
efflux pump components in
E. coli
strains expressing and deficient in the endogenous multidrug efflux system (AcrAB), although only the Δ
acrAB
strain, KZM120, demonstrated increased resistance to antibiotics in the presence of the
P. aeruginosa
efflux genes.
E. coli
KZM120 expressing MexAB-OprM showed increased resistance to quinolones, chloramphenicol, erythromycin, azithromycin, sodium dodecyl sulfate (SDS), crystal violet, novobiocin, and, significantly, several β-lactams, which is reminiscent of the operation of this pump in
P. aeruginosa
. This confirmed previous suggestions that MexAB-OprM provides a direct contribution to β-lactam resistance via the efflux of this group of antibiotics. An increase in antibiotic resistance, however, was not observed when MexAB or OprM alone was expressed in KZM120. Thus, despite the fact that β-lactams act within the periplasm, OprM alone is insufficient to provide resistance to these agents.
E. coli
KZM120 expressing MexCD-OprJ also showed increased resistance to quinolones, chloramphenicol, macrolides, SDS, and crystal violet, though not to most β-lactams or novobiocin, again somewhat reminiscent of the antibiotic resistance profile of MexCD-OprJ-expressing strains of
P. aeruginosa
. Surprisingly,
E. coli
KZM120 expressing MexCD alone also showed an increase in resistance to these agents, while an OprJ-expressing KZM120 failed to demonstrate any increase in antibiotic resistance. MexCD-mediated resistance, however, was absent in a
tolC
mutant of KZM120, indicating that MexCD functions in KZM120 in conjunction with TolC, the previously identified outer membrane component of the AcrAB-TolC efflux system. These data confirm that a tripartite efflux pump is necessary for the efflux of all substrate antibiotics and that the
P. aeruginosa
multidrug efflux pumps are functional and retain their substrate specificity in
E. coli.
Activity of Trovafloxacin (with or without Ampicillin-Sulbactam) against Enterococci in an In Vitro Dynamic Model of Infection
Authors: Zinner Stephen H. , Gilbert Deborah , Dudley Michael N. 
Published: October 2018

ABSTRACT

Antibiotic-resistant enterococci are being increasingly identified as causal agents of infection. Trovafloxacin is a new fluoronaphthyridone with enhanced activity against gram-positive cocci and variable activity reported against
Enterococcus
spp. Twenty-one strains of vancomycin-resistant
Enterococcus faecium
and two strains of
Enterococcus faecalis
(one vancomycin resistant) were studied at an initial inoculum of 10
6
CFU/ml in time-kill assays with trovafloxacin (3 mg/liter), ampicillin-sulbactam (100/50 mg/liter), and the combination. Six strains of
E. faecium
(five vancomycin resistant) also were studied in an in vitro two-compartment dynamic model that mimics human pharmacokinetics with trovafloxacin simulated at 300 mg every 12 h (q12h), ampicillin-sulbactam at 2/1 g q6h, and the combination. Peripheral compartments were sampled q2h for 30 h for bacterial counts. Trovafloxacin MICs ranged from 0.5 to 32 mg/liter, and the nine strains of vancomycin-resistant
E. faecium
for which MICs were ≤2 mg/liter were more likely to show a reduction of 2 log units or more in viable counts in time-kill assays than were strains for which MICs were higher. Synergism with ampicillin-sulbactam was found for only one strain (trovafloxacin MIC, 16 mg/liter). Similar results were obtained in the pharmacokinetic model, with 2- to 4-log-unit reductions in viable bacteria for trovafloxacin-susceptible strains. Although no convincing evidence of synergism was found, ampicillin-sulbactam in combination minimized late bacterial regrowth of two trovafloxacin-susceptible strains. These data suggest that this high dose of trovafloxacin (with or without ampicillin-sulbactam) might be useful against strains of vancomycin-resistant
E. faecium
for which MICs were ≤2 mg/liter.
Characterization of Mutations Contributing to Sulfathiazole Resistance in
Escherichia coli
Authors: Vedantam Gayatri , Guay Gordon G. , Austria Natasha E. , Doktor Stella Z. , Nichols Brian P. 
Published: October 2018

ABSTRACT

A sulfathiazole-resistant dihydropteroate synthase (DHPS) present in two different laboratory strains of
Escherichia coli
repeatedly selected for sulfathiazole resistance was mapped to
folP
by P1 transduction. The
folP
mutation in each of the strains was shown to be identical by nucleotide sequence analysis. A single C→T transition resulted in a Pro→Ser substitution at amino acid position 64. Replacement of the mutant
folP
alleles with wild-type
folP
significantly reduced the level of resistance to sulfathiazole but did not abolish it, indicating the presence of an additional mutation(s) that contributes to sulfathiazole resistance in the two strains. Transfer of the mutant
folP
allele to a wild-type background resulted in a strain with only a low level of resistance to sulfathiazole, suggesting that the presence of the resistant DHPS was not in itself sufficient to account for the overall sulfathiazole resistance in these strains of
E. coli
. Additional characterization of an amplified secondary resistance determinant,
sur
, present in one of the strains, identified it as the previously identified bicyclomycin resistance determinant
bcr
, a member of a family of membrane-bound multidrug resistance antiporters. An additional mutation contributing to sulfathiazole resistance,
sux
, has also been identified and has been shown to affect the histidine response to adenine sensitivity displayed by these
purU
strains.
Intracellular Delivery and Antibacterial Activity of Gentamicin Encapsulated in pH-Sensitive Liposomes
Authors: Lutwyche Peter , Cordeiro Carol , Wiseman David J. , St-Louis Maryse , Uh Mitchell , Hope Michael J. , Webb Murray S. , Finlay B. Brett 
Published: October 2018

ABSTRACT

Cell membranes are relatively impermeable to the antibiotic gentamicin, a factor that, along with the toxicity of gentamicin, precludes its use against many important intracellular bacterial infections. Liposomal encapsulation of this drug was used in order to achieve intracellular antibiotic delivery and therefore increase the drug’s therapeutic activity against intracellular pathogens. Gentamicin encapsulation in several dipalmitoylphosphatidylcholine (DPPC) and pH-sensitive dioleoylphosphatidylethanolamine (DOPE)-based carrier systems was characterized. To systematically test the antibacterial efficacies of these formulations, a tissue culture assay system was developed wherein murine macrophage-like J774A.1 cells were infected with bacteria and were then treated with encapsulated drug. Of these formulations, DOPE–
N
-succinyl-DOPE and DOPE–
N
-glutaryl-DOPE (70:30;mol:mol) containing small amounts of polyethyleneglycol-ceramide showed appreciable antibacterial activities, killing greater than 75% of intracellular vacuole-resident wild-type
Salmonella typhimurium
compared to the level of killing of the control formulations. These formulations also efficiently eliminated intracellular infections caused by a recombinant hemolysin-expressing
S. typhimurium
strain and a
Listeria monocytogenes
strain, both of which escape the vacuole and reside in the cytoplasm. Control non-pH-sensitive liposomal formulations of gentamicin had poor antibacterial activities. A fluorescence resonance energy transfer assay indicated that the efficacious formulations undergo a pH-dependent lipid mixing and fusion event. Intracellular delivery of the fluorescent molecules encapsulated in these formulations was confirmed by confocal fluorescence microscopy and was shown to be dependent on endosomal acidification. This work shows that encapsulation of membrane-impermeative antibiotics in appropriately designed lipid-based delivery systems can enable their use in treating intracellular infections and details the development of a general assay for testing the intracellular delivery of encapsulated drug formulations.